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Kim YM, Ghim MS, Quan M, Kim YY, Cho YS. Experimental Verification of the Impact of the Contact Area between the Defect Site and the Scaffold on Bone Regeneration Efficacy. Polymers (Basel) 2024; 16:338. [PMID: 38337228 DOI: 10.3390/polym16030338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/19/2024] [Accepted: 01/25/2024] [Indexed: 02/12/2024] Open
Abstract
In the field of bone tissue engineering, which is being developed for the ideal restoration of bone defects, researchers are exploring the improvement of the bone regeneration efficacy of scaffolds through various approaches involving osteoconductive, osteoinductive, and angiogenic factors. In the current trend of research, there is also a suggestion that the topological factors of recent scaffolds may influence the attachment, migration, proliferation, and differentiation of bone cells. Building upon experimental confirmation of the effect of scaffold conformity with the defect site on enhanced bone regeneration in previous studies, we conducted this research to experimentally investigate the relationship between contact area with the defect site and bone regeneration efficacy. The results demonstrated that as the contact area of the scaffold increased, not only did the resistance to bone tissue growth increase, more significant bone regeneration also occurred, as evidenced through histological analysis and micro-CT analysis. This research confirms that the contact area between the scaffold and the defect site is a critical variable affecting bone regeneration efficacy, emphasizing its importance when designing customized scaffolds. This finding holds promising implications for future studies and applications in the field.
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Affiliation(s)
- You Min Kim
- Division of Mechanical Engineering, Wonkwang University, 460 Iksandae-ro, Iksan 54538, Republic of Korea
| | - Min-Soo Ghim
- Division of Mechanical Engineering, Wonkwang University, 460 Iksandae-ro, Iksan 54538, Republic of Korea
| | - Meiling Quan
- Department of Pathophysiology, School of Basic Medical Sciences, Beihua University, Jilin 132021, China
- MECHABIO Group, Wonkwang University, 460 Iksandae-ro, Iksan 54538, Republic of Korea
| | - Young Yul Kim
- Department of Orthopedic Surgery, Daejeon St. Mary's Hospital, Catholic University of Korea, 64 Daeheung-ro, Daejeon 34943, Republic of Korea
| | - Young-Sam Cho
- Division of Mechanical Engineering, Wonkwang University, 460 Iksandae-ro, Iksan 54538, Republic of Korea
- MECHABIO Group, Wonkwang University, 460 Iksandae-ro, Iksan 54538, Republic of Korea
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Lyashenko IA, Pham TH, Popov VL. Effect of Indentation Depth on Friction Coefficient in Adhesive Contacts: Experiment and Simulation. Biomimetics (Basel) 2024; 9:52. [PMID: 38248626 PMCID: PMC10813419 DOI: 10.3390/biomimetics9010052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 12/31/2023] [Accepted: 01/10/2024] [Indexed: 01/23/2024] Open
Abstract
The quasi-static regime of friction between a rigid steel indenter and a soft elastomer with high adhesion is studied experimentally. An analysis of the formally calculated dependencies of a friction coefficient on an external load (normal force) shows that the friction coefficient monotonically decreases with an increase in the load, following a power law relationship. Over the entire range of contact loads, a friction mode is realized in which constant shear stresses are maintained in the tangential contact, which corresponds to the "adhesive" friction mode. In this mode, Amonton's law is inapplicable, and the friction coefficient loses its original meaning. Some classical works, which show the existence of a transition between "adhesive" and "normal" friction, were analyzed. It is shown that, in fact, there is no such transition. A computer simulation of the indentation process was carried out within the framework of the boundary element method, which confirmed the experimental results.
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Affiliation(s)
- Iakov A. Lyashenko
- Department of System Dynamics and Friction Physics, Institute of Mechanics, Technische Universität Berlin, 10623 Berlin, Germany; (T.H.P.); (V.L.P.)
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Huddleston HP, Connors K, Levy KH, Kurtzman JS, Hayes WT, Koehler SM. Proximal Row Carpectomy Does Not Alter Contact Pressures of the Lunate Fossa: A Cadaveric Study. Hand (N Y) 2024; 19:82-89. [PMID: 35815611 PMCID: PMC10786110 DOI: 10.1177/15589447221105542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
BACKGROUND Previous studies have suggested that proximal row carpectomy (PRC) results in increased contact pressures and decreased contact areas in the radiocarpal joint. Such experiments, however, used older technologies that may be associated with considerable measurement errors. The purpose of this study was to determine whether there was a significant difference in contact pressure and contact area before and after PRC using Tekscan, a newer pressure sensing technology. METHODS Ten nonpaired cadaveric specimens were dissected proximal to the carpal row and potted. An ultra-thin Tekscan sensor was secured in the lunate fossa of the radius. The wrists were loaded with 200 N of force for 60 seconds to simulate clenched-fist grip; contact pressure and area was assessed before and after PRC. RESULTS Performing a PRC did not significantly increase mean contact pressure at the lunate fossa compared to the native state (mean increase of 17.4 ± 43.2 N/cm2, P = .184). Similarly, the PRC did not significantly alter peak contact pressures at the lunate fossa (intact: 617.2 ± 233.46 N/cm2, median = 637.5 N/cm2; PRC: 707.8 ± 156.6 N/cm2, median = 728.5 N/cm2; P = .169). In addition, the PRC (0.46 ± 0.15 cm2, median = 0.48 cm2) and intact states (0.49 ± 0.25 cm2, median = 0.44 cm2) demonstrated similar contact areas (P = .681). CONCLUSIONS In contrast to prior studies that demonstrated significant increases in contact pressure and decreases in contact area after PRC, our findings propose that performing a PRC does not significantly alter the contact pressures or area of the lunate fossa of the radiocarpal joint.
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Ntallis C, Tzoupis H, Tselios T, Chasapis CT, Vlamis-Gardikas A. Distinct or Overlapping Areas of Mitochondrial Thioredoxin 2 May Be Used for Its Covalent and Strong Non-Covalent Interactions with Protein Ligands. Antioxidants (Basel) 2023; 13:15. [PMID: 38275635 PMCID: PMC10812433 DOI: 10.3390/antiox13010015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 12/09/2023] [Accepted: 12/16/2023] [Indexed: 01/27/2024] Open
Abstract
In silico approaches were employed to examine the characteristics of interactions between human mitochondrial thioredoxin 2 (HsTrx2) and its 38 previously identified mitochondrial protein ligands. All interactions appeared driven mainly by electrostatic forces. The statistically significant residues of HsTrx2 for interactions were characterized as "contact hot spots". Since these were identical/adjacent to putative thermodynamic hot spots, an energy network approach identified their neighbors to highlight possible contact interfaces. Three distinct areas for binding emerged: (i) one around the active site for covalent interactions, (ii) another antipodal to the active site for strong non-covalent interactions, and (iii) a third area involved in both kinds of interactions. The contact interfaces of HsTrx2 were projected as respective interfaces for Escherichia coli Trx1 (EcoTrx1), 2, and HsTrx1. Comparison of the interfaces and contact hot spots of HsTrx2 to the contact residues of EcoTx1 and HsTrx1 from existing crystal complexes with protein ligands supported the hypothesis, except for a part of the cleft/groove adjacent to Trp30 preceding the active site. The outcomes of this study raise the possibility for the rational design of selective inhibitors for the interactions of HsTrx2 with specific protein ligands without affecting the entirety of the functions of the Trx system.
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Affiliation(s)
- Charalampos Ntallis
- Department of Chemistry, University of Patras, 26504 Rion, Greece; (C.N.); (H.T.); (T.T.)
| | - Haralampos Tzoupis
- Department of Chemistry, University of Patras, 26504 Rion, Greece; (C.N.); (H.T.); (T.T.)
| | - Theodore Tselios
- Department of Chemistry, University of Patras, 26504 Rion, Greece; (C.N.); (H.T.); (T.T.)
| | - Christos T. Chasapis
- Institute of Chemical Biology, National Hellenic Research Foundation, Vas. Constantinou 48, 11635 Athens, Greece;
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Lee YK, Choi CS, Choi S, Park KW. A New Digital Analysis Technique for the Mechanical Aperture and Contact Area of Rock Fractures. Materials (Basel) 2023; 16:1538. [PMID: 36837168 PMCID: PMC9967890 DOI: 10.3390/ma16041538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 02/08/2023] [Accepted: 02/10/2023] [Indexed: 06/18/2023]
Abstract
In this study, a new digital technique for the analysis of the mechanical aperture and contact area of rock fractures under various normal stresses is proposed. The technique requires point cloud data of the upper and lower fracture surfaces, pressure film image data of the fracture, and normal deformation data of the fracture as input data. Three steps of algorithms were constructed using these input data: (1) a primary matching algorithm that considers the shape of the fracture surfaces; (2) a secondary matching algorithm that uses pressure film images; and (3) a translation algorithm that considers the normal deformation of a fracture. The applicability of the proposed technique was investigated using natural fracture specimens sampled at an underground research facility in Korea. In this process, the technique was validated through a comparison with the empirical equation suggested in a previous study. The proposed technique has the advantage of being able to analyze changes in the mechanical aperture and contact area under various normal stresses without multiple experiments. In addition, the change in the contact area on the fracture surface according to the normal stress can be analyzed in detail.
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Affiliation(s)
- Yong-Ki Lee
- Disposal Performance Demonstration Research Division, Korea Atomic Energy Research Institute (KAERI), 111 Daedeok-daero, 989 Beon-gil, Yuseong-gu, Daejeon 34057, Republic of Korea
| | - Chae-Soon Choi
- Disposal Performance Demonstration Research Division, Korea Atomic Energy Research Institute (KAERI), 111 Daedeok-daero, 989 Beon-gil, Yuseong-gu, Daejeon 34057, Republic of Korea
| | - Seungbeom Choi
- Disposal Safety Evaluation Research Division, Korea Atomic Energy Research Institute (KAERI), 111 Daedeok-daero, 989 Beon-gil, Yuseong-gu, Daejeon 34057, Republic of Korea
| | - Kyung-Woo Park
- Disposal Performance Demonstration Research Division, Korea Atomic Energy Research Institute (KAERI), 111 Daedeok-daero, 989 Beon-gil, Yuseong-gu, Daejeon 34057, Republic of Korea
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Wu N, Guo Q, Xie X, Chen L. Friction Behavior between Carbon Fiber Plain Weave and Metal Semi-Cylinder Tool. Polymers (Basel) 2023; 15:472. [PMID: 36679352 DOI: 10.3390/polym15020472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 12/28/2022] [Accepted: 01/10/2023] [Indexed: 01/19/2023] Open
Abstract
The deformations that occur during composite forming processes are governed by the friction between the fabrics and tooling material on the mesoscopic level. The effect of normal load and multi-plies on the frictional behavior of the carbon plain weave is investigated by simulating the friction between the fabric and metal semi-cylinder tool by using the experimental method. The periodic wavy friction-displacement curve between the metal tool and fabric is caused by the interwoven structure of the fabric. Both the increase in the normal load and the number of layers cause an increase in the real contact area during friction, leading to an increase in the friction force. The real contact area is calculated based on the Hertzian contact model and the self-designed testing method. The friction force values obtained from multiplying the real contact area with shear strength are closely aligned with the measured results.
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Guo Q, Zou Z, Xie Y, Lan X, Zhu G, Xu K, Jin R, Xu W, Huang G, Li Y, Wang T, Du W. In Situ Active Switching of Bipolar Current Rectification in 2D Semiconductor Vertical Diodes. ACS Appl Mater Interfaces 2023; 15:1583-1591. [PMID: 36537368 DOI: 10.1021/acsami.2c18370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Two-dimensional semiconducting transition-metal dichalcogenides (TMDCs) have attracted extensive attention as building blocks of miniaturized electronic and optical devices. However, as the characteristics of TMDC devices are predominately determined by their device structures, the function of TMDC devices is fixed once fabricated, leaving the reconfigurable active device and circuit a challenge. Here, we have demonstrated the current rectification switching in TMDC vertical diodes using a liquid metal (EGaIn) top electrode with a reconfigurable contact area. The rectification switching is closely related to the ultrathin gallium oxide layer on the surface of EGaIn. Under the small contact, with the existence of gallium oxide, photocurrent dominates the electrical transport showing a negative rectification, while as the contact increases, the broken gallium oxide leads to rectification switching to the positive bias direction. Such rectification switching applies to thin TMDC flakes down to 3 nm, benefitting from the soft electrical contact between the TMDC and the EGaIn electrode. Our work shows the new possibility of actively reconfigurable TMDC vertical diodes enabled by the liquid metal electrode and will promote promising applications of flexible and tunable TMDC-based nanoelectronic devices.
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Affiliation(s)
- Qianqian Guo
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, P. R. China
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215123, Jiangsu, P. R. China
| | - Zhen Zou
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, P. R. China
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215123, Jiangsu, P. R. China
| | - Yu Xie
- Key Laboratory of Organic Optoelectronics and Molecular Engineering and Laboratory of Flexible Electronics Technology, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Xinhui Lan
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, P. R. China
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215123, Jiangsu, P. R. China
| | - Guangpeng Zhu
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, P. R. China
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215123, Jiangsu, P. R. China
| | - Kai Xu
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, P. R. China
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215123, Jiangsu, P. R. China
| | - Ran Jin
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, P. R. China
| | - Wenrui Xu
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, P. R. China
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215123, Jiangsu, P. R. China
| | - Guangyan Huang
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, P. R. China
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215123, Jiangsu, P. R. China
| | - Yuan Li
- Key Laboratory of Organic Optoelectronics and Molecular Engineering and Laboratory of Flexible Electronics Technology, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Tao Wang
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, P. R. China
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215123, Jiangsu, P. R. China
| | - Wei Du
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, P. R. China
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215123, Jiangsu, P. R. China
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Lyashenko IA, Popov VL, Pohrt R, Borysiuk V. High-Precision Tribometer for Studies of Adhesive Contacts. Sensors (Basel) 2023; 23:456. [PMID: 36617054 PMCID: PMC9824799 DOI: 10.3390/s23010456] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/22/2022] [Accepted: 12/28/2022] [Indexed: 06/17/2023]
Abstract
Herein, we describe the design of a laboratory setup operating as a high-precision tribometer. The whole design procedure is presented, starting with a concept, followed by the creation of an exact 3D model and final assembly of all functional parts. The functional idea of the setup is based on a previously designed device that was used to perform more simple tasks. A series of experiments revealed certain disadvantages of the initial setup, for which pertinent solutions were found and implemented. Processing and correction of the data obtained from the device are demonstrated with an example involving backlash and signal drift errors. Correction of both linear and non-linear signal drift errors is considered. We also show that, depending on the research interests, the developed equipment can be further modified by alternating its peripheral parts without changing the main frame of the device.
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Affiliation(s)
- Iakov A. Lyashenko
- Department of System Dynamics and Friction Physics, Institute of Mechanics, Technische Universität Berlin, 10623 Berlin, Germany
- Department of Applied Mathematics and Complex Systems Modeling, Faculty of Electronics and Information Technology, Sumy State University, 40007 Sumy, Ukraine
| | - Valentin L. Popov
- Department of System Dynamics and Friction Physics, Institute of Mechanics, Technische Universität Berlin, 10623 Berlin, Germany
| | - Roman Pohrt
- Department of System Dynamics and Friction Physics, Institute of Mechanics, Technische Universität Berlin, 10623 Berlin, Germany
| | - Vadym Borysiuk
- Department of System Dynamics and Friction Physics, Institute of Mechanics, Technische Universität Berlin, 10623 Berlin, Germany
- Department of Nanoelectronics and Surface Modification, Faculty of Electronics and Information Technology, Sumy State University, 40007 Sumy, Ukraine
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Alqahtani NM, Alqahtani AF, Zarbah MA, Alqahtani SM, Shukla AK, Kulkarni MM. Assessment of PCL between dental implant prosthesis and natural teeth using a digital force analyzer. Technol Health Care 2022; 30:1435-1442. [PMID: 35661036 DOI: 10.3233/thc-220028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND The prime concern of an implant-supported prosthesis (ISP) is to maintain an optimal proximal contact tightness, which further maintains arch integrity, improves masticatory effectiveness, and minimizes peri-implantitis. OBJECTIVE To investigate the loss of proximal contact tightness between single tooth implant-supported prosthesis and the adjacent natural teeth. METHODS Forty patients treated by a single mandibular first molar ISP, aged between 18-50 years were selected. All were randomly allocated in Group I and Group II. Group I, 20 subjects who have received ISP without an insertion of Essix retainer, and Group II patients received an insertion with Essix retainer. The groups were subdivided into Subgroup A, B, and Subgroup C, D, in which A and C are control groups. To measure the tightness at proximal contact points, a digital force analyzer was used. Proximal contact tightness (PCT) was measured immediately after the placement of the prosthesis, 3 months, 6 months, and 1-year follow-up respectively, and the PCT values at end of 1 year were statistically evaluated. Statistical analysis was done, mean and standard deviation was calculated by independent sample t-test wit p< 0.05 as a statistically significant value. RESULTS In Group I, towards the end of 1 year, 2.09 N (65.5%) and 1.50 N (53.1%) loss of PCT were found on mesial and distal contact areas respectively. In Group II, loss of PCT at mesial contact area was 0.87 N (28.9%) and at distal contact area was 1.77 N (53.3%), which is significantly less compared with the non-usage of Essix retainer (p< 0.05). CONCLUSION The usage of Essix retainer, PCT increases especially on the mesial contact area. The frequency of contact loss was decreased. Thus, to minimize the loss of proximal contact the usage of Essix retainer is recommended.
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Affiliation(s)
- Nasser M Alqahtani
- Department of Prosthetic Dentistry, College of Dentistry, King Khalid University, Abha, Saudi Arabia
| | - Ali Fahed Alqahtani
- Department of Periodontics and Community Dentistry, College of Dentistry, King Khalid University, Abha, Saudi Arabia
| | - Mohammad A Zarbah
- Department of Prosthetic Dentistry, College of Dentistry, King Khalid University, Abha, Saudi Arabia
| | - Saeed M Alqahtani
- Department of Prosthetic Dentistry, College of Dentistry, King Khalid University, Abha, Saudi Arabia
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Li W, Bao Z, Du Q, Xu Y, Jiao K. Open-Source CFD Elucidating Mechanism of 3D Pillar Electrode in Improving All-Solid-State Battery Performance. Adv Sci (Weinh) 2022; 9:e2105454. [PMID: 35132801 PMCID: PMC9069203 DOI: 10.1002/advs.202105454] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 01/15/2022] [Indexed: 06/14/2023]
Abstract
All-solid-state batteries (ASSBs) have become an important technology because of their high performance and low-risk operation. However, the high interface resistance and low ionic conductivity of ASSBs hinder their application. In this study, a self-developed electrochemical model based on an open-source computational fluid dynamics platform is presented. The effect of contact area reduction at the electrode/solid-state electrolyte interface is investigated. Then, a new conceptual 3D structure is introduced to circumvent the existing barriers. The results demonstrate that the discharge time is shortened by over 20% when the area contact ratio reduces from 1.0 to 0.8 at 1 C-rate, owing to the increased overpotential. By adopting the new 3D pillar design, the energy density of ASSBs can be improved. However, it is only when a 3D current collector is contained in the cathode that the battery energy/power density, capacity, and material utilization can be greatly enhanced without being limited by pillar height issues. Therefore, this work provides important insight into the enhanced performance of 3D structures.
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Affiliation(s)
- Weizhuo Li
- State Key Laboratory of EnginesTianjin University135 Yaguan RdTianjin300350China
| | - Zhiming Bao
- State Key Laboratory of EnginesTianjin University135 Yaguan RdTianjin300350China
| | - Qing Du
- State Key Laboratory of EnginesTianjin University135 Yaguan RdTianjin300350China
| | - Yifan Xu
- State Key Laboratory of EnginesTianjin University135 Yaguan RdTianjin300350China
| | - Kui Jiao
- State Key Laboratory of EnginesTianjin University135 Yaguan RdTianjin300350China
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Muratov KR, Ablyaz TR, Gashev EA, Goryacheva IG. Investigation of Technological and Load Intensity Parameters of the Finishing Process of Materials on Equipment with Tools Translational Kinematics. Materials (Basel) 2022; 15:3048. [PMID: 35591385 DOI: 10.3390/ma15093048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/14/2022] [Accepted: 04/20/2022] [Indexed: 02/04/2023]
Abstract
The regularities of the formation of the resulting raster tool trajectories based on Lissajous figures for the lapping process of planes are established. This makes it possible to maximize the cutting ability of the tool, which contributes to its more uniform wear and increased productivity and processing quality. Optimal parameters of productivity and roughness of the treated surface during lapping of zirconium ceramics are achieved through the use of ASM paste 28/20 µm. Based on Preston’s hypothesis, an exponential dependence of the change in the contact area during the lapping of planes of different initial shape of the macrorelief is obtained. The obtained theoretical and practical results of the study of the process of flat lapping with constant and variable clamping force of the treated surface to the surface of the tool. The influence of the force factor on the formation of the surface in the process of abrasive lapping has been established. Studies have been carried out and the main technological recommendations of precision surface treatment of workpieces based on hard, brittle ceramic material and bronze samples on equipment with a raster trajectory of the tool movement are presented. The optimal pressure value when processing ceramics should be considered 203–270 kPa (2.1–2.8 kg/cm2).
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Berkmortel CJ, Szmit J, Langohr GD, King GJW, Johnson JA. The effect of hemiarthroplasty implant modulus on contact mechanics: an experimental investigation. J Shoulder Elbow Surg 2021; 30:2845-2851. [PMID: 34293420 DOI: 10.1016/j.jse.2021.06.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 06/05/2021] [Accepted: 06/12/2021] [Indexed: 02/01/2023]
Abstract
BACKGROUND Hemiarthroplasties cause damage to the cartilage that they articulate against, which is a major limitation to their use. This study investigated the use of lower-stiffness materials to determine whether they improve hemiarthroplasty contact mechanics and thus reduce the risk of cartilage damage. METHODS Eleven fresh-frozen cadaveric upper extremities were disarticulated and fixed in a custom-built jig that applied a static load of 50 N to the radiocapitellar joint. Flexion angles of 0°, 45°, 90°, and 135° were tested with radial head implants made of cobalt-chrome (CoCr) and ultrahigh-molecular-weight polyethylene (UHMWPE) compared with the native radial head. A Tekscan thin-film sensor was used to measure the contact area and contact pressure between the radius and capitellum. RESULTS UHMWPE and CoCr were too stiff in the application of hemiarthroplasty, resulting in lower contact areas and higher contact pressures relative to the native joint. The native contact area was, on average, 42 ± 20 mm2 larger than that of UHMWPE (P < .001) and 55 ± 24 mm2 larger than that of CoCr (P < .001). UHMWPE had a contact area 13 ± 10 mm2 greater than that of CoCr (P = .014). DISCUSSION AND CONCLUSION This study shows that even though UHMWPE has a stiffness several times lower than CoCr, the use of this material in hemiarthroplasty led to only a minor improvement in contact mechanics. Neither implant restored contact similar to the native articulation. Investigations into new materials to improve the contact mechanics of hemiarthroplasty should focus on materials with a lower stiffness than UHMWPE.
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Affiliation(s)
- Carolyn J Berkmortel
- Department of Mechanical and Materials Engineering, Western University, London, ON, Canada
| | - Jakub Szmit
- Bioengineering Laboratory, Roth McFarlane Hand and Upper Limb Centre, Lawson Health Research Institute, St Joseph's Health Care, London, ON, Canada; Department of Surgery, Western University, London, ON, Canada
| | - G Daniel Langohr
- Department of Mechanical and Materials Engineering, Western University, London, ON, Canada; Bioengineering Laboratory, Roth McFarlane Hand and Upper Limb Centre, Lawson Health Research Institute, St Joseph's Health Care, London, ON, Canada
| | - Graham J W King
- Bioengineering Laboratory, Roth McFarlane Hand and Upper Limb Centre, Lawson Health Research Institute, St Joseph's Health Care, London, ON, Canada; Department of Surgery, Western University, London, ON, Canada
| | - James A Johnson
- Department of Mechanical and Materials Engineering, Western University, London, ON, Canada; Bioengineering Laboratory, Roth McFarlane Hand and Upper Limb Centre, Lawson Health Research Institute, St Joseph's Health Care, London, ON, Canada; Department of Surgery, Western University, London, ON, Canada.
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Rusu L, Paun E, Marin MI, Hemanth J, Rusu MR, Calina ML, Bacanoiu MV, Danoiu M, Danciulescu D. Plantar Pressure and Contact Area Measurement of Foot Abnormalities in Stroke Rehabilitation. Brain Sci 2021; 11:1213. [PMID: 34573233 PMCID: PMC8469353 DOI: 10.3390/brainsci11091213] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 08/27/2021] [Accepted: 09/08/2021] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Evaluation of plantar pressure in stroke patients is a parameter that could be used for monitoring and comparing how the timing of starting a rehabilitation program effects patient improvement. METHODS We performed the following clinical and functional evaluations: initial moment (T1), intermediate (T2), and final evaluation at one year (T3). At T1 we studied 100 stroke patients in two groups, A and B (each 50 patients). The first group, A, started rehabilitation in the first three months after having a stroke, and group B started after three months from the time of stroke. Due to the impediments observed during rehabilitation, we made biomechanic evaluation for two lots, I and II (each 25 patients). Assessment of the patient was carried out by clinical (neurologic examination), functional (using the Tinetti Functional Gait Assessment Test for classifying the gait), and biomechanical evaluation (maximal plantar pressure (Pmax), contact area (CA), and pressure distribution (COP)). RESULTS The Tinetti scale for gait had the following scores: for group A, from 1.34 at the initial moment (T1) to 10.64 at final evaluation (T3), and for group B, 3.08 at initial moment (T1) to 9 at final evaluation (T3). Distribution of COP in the left hemiparesis was uneven at T1 but evolved after rehabilitation. The right hemiparesis had uniform COP distribution even at T1, explained by motor dominance on the right side. CA and Pmax for lot I increased more than 100%, meaning that there is a possibility for favorable improvement if the patients start the rehabilitation program in the first three months after stroke. For lot II, increases of the parameters were less than lot I. DISCUSSIONS The recovery potential is higher for patients with right hemiparesis. Biomechanic evaluation showed diversity regarding compensatory mechanisms for the paretic and nonparetic lower limb. CONCLUSIONS CA and Pmax are relevant assessments for evaluating the effects on timing of starting a rehabilitation program after a stroke.
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Affiliation(s)
- Ligia Rusu
- Sport Medicine and Physiotherapy Department, University of Craiova, 200585 Craiova, Romania
| | - Elvira Paun
- Sport Medicine and Physiotherapy Department, University of Craiova, 200585 Craiova, Romania
| | - Mihnea Ion Marin
- Faculty of Mechanics, University of Craiova, 200585 Craiova, Romania
| | - Jude Hemanth
- Department of ECE, Karunya Institute of Technology and Sciences, Coimbatore 641114, India
| | - Mihai Robert Rusu
- Sport Medicine and Physiotherapy Department, University of Craiova, 200585 Craiova, Romania
| | - Mirela Lucia Calina
- Sport Medicine and Physiotherapy Department, University of Craiova, 200585 Craiova, Romania
| | | | - Mircea Danoiu
- Sport Medicine and Physiotherapy Department, University of Craiova, 200585 Craiova, Romania
| | - Daniel Danciulescu
- Sport Medicine and Physiotherapy Department, University of Craiova, 200585 Craiova, Romania
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Muthu MS, Kirthiga M, Lee JC, Kayalvizhi G, Mathur VP, Kandaswamy D, Jayakumar N. OXIS Contacts as a Risk Factor for Approximal Caries: A Retrospective Cohort Study. Pediatr Dent 2021; 43:296-300. [PMID: 34467847 PMCID: PMC7612504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Purpose: The purpose of the present study was to evaluate the individual susceptibility of four different types of OXIS contact areas (open [O], point [X], straight [I], and curved [S]) to approximal caries in children. Methods: A retrospective cohort study was performed using clinical photographs and cone-beam computed tomography images of children, available from January 1, 2014, to August 31, 2015, showing the presence of at least one caries-free contact area between the primary molars. A single calibrated examiner scored 1,102 selected contacts using OXIS criteria from the occlusal view and subsequently evaluated the same contacts with a minimum follow-up period of one year for the presence of approximal caries. Results: Of the 1,102 contacts, 259 (23.5 percent) were found to be carious or restored due to approximal caries. Multivariate logistic regression analysis showed that only the type of contact played a significant role in caries prevalence (P<0.05). The odds ratios of OXIS contacts for the development of approximal caries were: S contact-147.4 (95 percent confidence interval [95% CI] equals 19.7 to 1101.7); I contact-24.5 (95% CI equals 3.4 to 177.9); X contact-1.1 (95% CI equals 1.0 to 12.5); and O contact-1.00 (reference). Conclusions: Among the OXIS contacts, the S type was most susceptible to approximal caries due to its complex morphology. The broad contact areas, namely, I and S types, are at greater risk for approximal caries in primary molars than O and X contacts.
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Affiliation(s)
- M S Muthu
- Dr. Muthu MS is a professor and head, Centre for Early Childhood Caries Research, Department of Pediatric and Preventive Dentistry, Faculty of Dental Sciences, Sri Ramachandra Institute of Higher Education and Research; and an adjunct research associate, Centre of Medical and Bio-Allied Health Sciences Research, Ajman University, United Arab Emirates
| | - M Kirthiga
- Dr. Kirthiga M is an assistant professor, Centre for Early Childhood Caries Research, Department of Pediatric and Preventive Dentistry, Faculty of Dental Sciences, Sri Ramachandra Institute of Higher Education and Research, Chennai, Tamil Nadu; and a Early Career Fellow, Wellcome Trust (UK) DBT India Alliance, Hyderabad, India; kirthi487@gmail. com
| | | | - Gurusamy Kayalvizhi
- Dr. Kayalvizhi is a professor and head, Department of Pedodontics and Preventive Dentistry, Syamala Reddy Dental College, Bangalore, Karnataka, India
| | - Vijay Prakash Mathur
- Dr. Mathur is a professor and head, Division of Pedodontics and Preventive Dentistry, Centre for Dental Education and Research, All India Institute of Medical Sciences, New Delhi, India
| | - Deivanayagam Kandaswamy
- Dr. Kandaswamy is a former dean, Department of Oral and Maxillofacial Surgery, Faculty of Dental Sciences, Sri Ramachandra Institute of Higher Education and Research, Chennai, India
| | - Naveen Jayakumar
- Dr. Jayakumar is a professor and head, Department of Oral and Maxillofacial Surgery, Faculty of Dental Sciences, Sri Ramachandra Institute of Higher Education and Research, Chennai, India
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Mei C, Wu W. Fracture asperity evolution during the transition from stick slip to stable sliding. Philos Trans A Math Phys Eng Sci 2021; 379:20200133. [PMID: 33715413 DOI: 10.1098/rsta.2020.0133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/06/2020] [Indexed: 06/12/2023]
Abstract
Fracture asperities interlock or break during stick slip and ride over each other during stable sliding. The evolution of fracture asperities during the transition between stick slip and stable sliding has attracted less attention, but is important to predict fracture behaviour. Here, we conduct a series of direct shear experiments on simulated fractures in homogeneous polycarbonate to examine the evolution of fracture asperities in the transition stage. Our results show that the transition stage occurs between the stick slip and stable sliding stages during the progressive reduction in normal stress on the smooth and rough fractures. Both the fractures exhibit the alternative occurrence of small and large shear stress drops followed by the deterministic chaos in the transition stage. Our data indicate that the asperity radius of curvature correlates linearly with the dimensionless contact area under a given normal stress. For the rough fracture, a bifurcation of acoustic energy release appears when the dimensionless contact area decreases in the transition stage. The evolution of fracture asperities is stress-dependent and velocity-dependent. This article is part of the theme issue 'Fracture dynamics of solid materials: from particles to the globe'.
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Affiliation(s)
- Cheng Mei
- School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
| | - Wei Wu
- School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
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Kakani V, Cui X, Ma M, Kim H. Vision-Based Tactile Sensor Mechanism for the Estimation of Contact Position and Force Distribution Using Deep Learning. Sensors (Basel) 2021; 21:1920. [PMID: 33803481 DOI: 10.3390/s21051920] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 03/04/2021] [Accepted: 03/05/2021] [Indexed: 11/16/2022]
Abstract
This work describes the development of a vision-based tactile sensor system that utilizes the image-based information of the tactile sensor in conjunction with input loads at various motions to train the neural network for the estimation of tactile contact position, area, and force distribution. The current study also addresses pragmatic aspects, such as choice of the thickness and materials for the tactile fingertips and surface tendency, etc. The overall vision-based tactile sensor equipment interacts with an actuating motion controller, force gauge, and control PC (personal computer) with a LabVIEW software on it. The image acquisition was carried out using a compact stereo camera setup mounted inside the elastic body to observe and measure the amount of deformation by the motion and input load. The vision-based tactile sensor test bench was employed to collect the output contact position, angle, and force distribution caused by various randomly considered input loads for motion in X, Y, Z directions and RxRy rotational motion. The retrieved image information, contact position, area, and force distribution from different input loads with specified 3D position and angle are utilized for deep learning. A convolutional neural network VGG-16 classification modelhas been modified to a regression network model and transfer learning was applied to suit the regression task of estimating contact position and force distribution. Several experiments were carried out using thick and thin sized tactile sensors with various shapes, such as circle, square, hexagon, for better validation of the predicted contact position, contact area, and force distribution.
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Baby R, Mathur K, DenHartog E. Nondestructive Quantitative Evaluation of Yarns and Fabrics and Determination of Contact Area of Fabrics Using the X-ray Microcomputed Tomography System for Skin-Textile Friction Analysis. ACS Appl Mater Interfaces 2021; 13:4652-4664. [PMID: 33428371 DOI: 10.1021/acsami.0c18300] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
In different mechanical conditions, repetitive friction in combination with pressure, shear, temperature, and moisture leads to skin discomfort and imposes the risks of developing skin injuries such as blisters and pressure ulcers, frequently reported in athletes, military personnel, and in people with compromised skin conditions and/or immobility. Textiles next to skin govern the skin microclimate, have the potential to influence the mechanical contact with skin, and contribute to skin comfort and health. The adhesion-friction theory suggests that contact area is a critical factor to influence adhesion, and therefore, friction force. Friction being a surface phenomenon, most of the studies concentrated on the surface profile or topographic analysis of textiles. This study investigated both the surface profiles and the inner construction of the fabrics through X-ray microcomputed tomographic three-dimensional image analysis. A novel nondestructive method to evaluate yarn and fabric structural details quantitatively and calculate contact area (in fiber area %) experimentally has been reported in this paper. Plain and satin-woven fabrics with different thread densities and made from 100% cotton ring-spun yarns with two different linear densities (40 and 60 Ne) were investigated in this study. The measurements from the tomographic images (pixel size: 1.13 μm) and the fiber area % analysis were in good agreement to comprehend and compare the yarn and fabric properties reported. The fiber area % as reported in this paper can be used to evaluate the skin-textile interfaces and quantitatively determine the contact area under different physical, mechanical, and microclimatic conditions to understand the actual skin-textile interaction during any physical activity or sports. The proposed method can be helpful in engineering textiles to enhance skin comfort and prevent injuries, such as blisters and pressure ulcers, in diversified application areas, including but not limited to, sports and healthcare apparel, military apparel, and firefighter's protective clothing. In addition, the images were capable of precisely evaluating yarn diameters, crimp %, and packing factor as well as fabric thickness, volumetric densities, and cover factors as compared with those obtained from theoretical evaluation and existing classical test methods. All these findings suggest that the proposed new method can reliably be used to quantify the yarn and fabric characteristics, compare their functionality, and understand the structural impacts in an objective and nondestructive way.
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Affiliation(s)
- Ruksana Baby
- Wilson College of Textiles, North Carolina State University, Raleigh, North Carolina 27606, United States
| | - Kavita Mathur
- Wilson College of Textiles, North Carolina State University, Raleigh, North Carolina 27606, United States
| | - Emiel DenHartog
- Wilson College of Textiles, North Carolina State University, Raleigh, North Carolina 27606, United States
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Keum K, Heo JS, Eom J, Lee KW, Park SK, Kim YH. Highly Sensitive Textile-Based Capacitive Pressure Sensors Using PVDF-HFP/Ionic Liquid Composite Films. Sensors (Basel) 2021; 21:s21020442. [PMID: 33435515 PMCID: PMC7827140 DOI: 10.3390/s21020442] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/07/2021] [Accepted: 01/08/2021] [Indexed: 02/07/2023]
Abstract
Textile-based pressure sensors have garnered considerable interest in electronic textiles due to their diverse applications, including human–machine interface and healthcare monitoring systems. We studied a textile-based capacitive pressure sensor array using a poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP)/ionic liquid (IL) composite film. By constructing a capacitor structure with Ag-plated conductive fiber electrodes that are embedded in fabrics, a capacitive pressure sensor showing high sensitivity, good operation stability, and a wide sensing range could be created. By optimizing the PVDF-HFP:IL ratio (6.5:3.5), the fabricated textile pressure sensors showed sensitivity of 9.51 kPa−1 and 0.69 kPa−1 in the pressure ranges of 0–20 kPa and 20–100 kPa, respectively. The pressure-dependent capacitance variation in our device was explained based on the change in the contact-area formed between the multi-filament fiber electrodes and the PVDF-HFP/IL film. To demonstrate the applicability and scalability of the sensor device, a 3 × 3 pressure sensor array was fabricated. Due to its matrix-type array structure and capacitive sensing mechanism, multi-point detection was possible, and the different positions and the weights of the objects could be identified.
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Affiliation(s)
- Kyobin Keum
- School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 16419, Korea; (K.K.); (J.S.H.)
| | - Jae Sang Heo
- School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 16419, Korea; (K.K.); (J.S.H.)
| | - Jimi Eom
- Advanced Textile R&D Department, Research Institute of Convergence Technology, Korea Institute of Industrial Technology (KITECH), Ansan 15588, Korea;
| | - Keon Woo Lee
- School of Electrical and Electronic Engineering, Chung-Ang University, Seoul 06974, Korea;
| | - Sung Kyu Park
- School of Electrical and Electronic Engineering, Chung-Ang University, Seoul 06974, Korea;
- Correspondence: (S.K.P.); (Y.-H.K.)
| | - Yong-Hoon Kim
- School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 16419, Korea; (K.K.); (J.S.H.)
- SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 16419, Korea
- Correspondence: (S.K.P.); (Y.-H.K.)
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Cheng BC, Swink I, Yusufbekov R, Birgelen M, Ferrara L, Lewandrowski KU, Coric D. Current Concepts of Contemporary Expandable Lumbar Interbody Fusion Cage Designs, Part 1: An Editorial on Their Biomechanical Characteristics. Int J Spine Surg 2020; 14:S63-S67. [PMID: 33122179 DOI: 10.14444/7128] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Bidirectional expandable designs for lumbar interbody fusion cages are the latest iteration of expandable spacers employed to address some of the common problems inherent to static interbody fusion cages. OBJECTIVE To describe the rationales for contemporary bidirectional, multimaterial expandable lumbar interbody fusion cage designs to achieve in situ expansion for maximum anterior column support while decreasing insertion size during minimal-access surgeries. METHODS The authors summarize the current concepts behind expandable spinal fusion open architecture cage designs focusing on advanced minimally invasive spinal surgery techniques, such as endoscopy. A cage capable of bidirectional expansion in both height and width to address constrained surgical access problems was of particular interest to the authors while they analyzed the relationship between implant material stiffness and geometric design regarding the risk of subsidence and reduced graft loading. CONCLUSIONS Biomechanical advantages of new bidirectional, multimaterial expandable interbody fusion cages allow insertion through minimal surgical access and combine the advantages of proven device configurations and advanced material selection. The final construct stiffness is sufficient to provide immediate anterior column support while accommodating reduced sizes required for minimally invasive surgery applications. LEVEL OF EVIDENCE 7.
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Affiliation(s)
- Boyle C Cheng
- Department of Neurosurgery, Allegheny Health Network, Pittsburgh, Pennsylvania
| | - Isaac Swink
- Department of Neurosurgery, Allegheny Health Network, Pittsburgh, Pennsylvania
| | | | - Michele Birgelen
- Department of Neurosurgery, Allegheny Health Network, Pittsburgh, Pennsylvania
| | - Lisa Ferrara
- OrthoKinetic Technologies LLC, Southport, North Carolina
| | - Kai-Uwe Lewandrowski
- Center for Advanced Spine Care of Southern Arizona and Surgical Institute of Tucson, Arizona
| | - Domagoj Coric
- Carolina Neurosurgery & Spine Associates, Charlotte, North Carolina.,Atrium Musculoskeletal Institute, Charlotte, North Carolina
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Kishima H, Mine T, Fukuhara E, Takahashi S, Ishihara M. Is the abnormal conduction zone of the left atrium a precursor to a low voltage area in patients with atrial fibrillation? J Cardiovasc Electrophysiol 2020; 31:2874-2882. [PMID: 32936499 DOI: 10.1111/jce.14744] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/08/2020] [Accepted: 09/14/2020] [Indexed: 01/04/2023]
Abstract
BACKGROUND The abnormal conduction zone (ACZ) in the left atrium (LA) has attracted attention as an arrhythmia source in atrial fibrillation (AF). We investigated the hypothesis that the ACZ is related to the low voltage area (LVA) or the LA anatomical contact areas (CoAs) with other organs. METHODS AND RESULTS We studied 100 patients (49 non-paroxysmal AF, 66 males, and 67.9 ± 9.9 years) who received catheter ablation for AF. High-density LA mapping during high right atrial pacing was constructed. Isochronal activation maps were created at 5-ms interval setting, and the ACZ was identified on the activation map by locating a site with isochronal crowding of ≥3 isochrones, which are calculated as ≤27 cm/s. The LVA was defined as the following; mild ( < 1.3 mV), moderate (<1.0 mV), and severe LVA (<0.5 mV). The CoAs (ascending aorta-anterior LA, descending aorta-posterior LA, and vertebrae-posterior LA) were assessed using computed tomography. The ACZ was linearly distributed, and observed in 95 patients (95%). The ACZ was most frequently observed in the anterior wall region (77%). A longer ACZ was significantly associated with a larger LA size and a prevalence of non-PAF. The 51.2 ± 36.2% of ACZ overlapped with mild LVA, 32.9 ± 32.8% of ACZ with moderate LVA, and 14.6 ± 22.0% of ACZ with severe LVA. In contrast, only 25.6 ± 28.0% of ACZ matched with the CoAs. CONCLUSION The ACZ reflects LA electrical remodeling and may be a precursor finding of the low voltage zone and not the LA CoAs in patients with atrial fibrillation.
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Affiliation(s)
- Hideyuki Kishima
- Department of Cardiovascular and Renal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Takanao Mine
- Department of Cardiovascular and Renal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Eiji Fukuhara
- Department of Cardiovascular and Renal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Satoshi Takahashi
- Department of Cardiovascular Medicine, Kawasaki Hospital, Kobe, Japan
| | - Masaharu Ishihara
- Department of Cardiovascular and Renal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
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Ules T, Hausberger A, Grießer M, Schlögl S, Gruber DP. Introduction of a New In-Situ Measurement System for the Study of Touch-Feel Relevant Surface Properties. Polymers (Basel) 2020; 12:E1380. [PMID: 32575513 DOI: 10.3390/polym12061380] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 06/09/2020] [Accepted: 06/16/2020] [Indexed: 12/13/2022] Open
Abstract
The touch-feel sensation of product surfaces arouses growing interest in various industry branches. To entangle the underlying physical and material parameters responsible for a specific touch-feel sensation, a new measurement system has been developed. This system aims to record the prime physical interaction parameters at a time, which is considered a necessary prerequisite for a successful physical description of the haptic sensation. The measurement setup enables one to measure the dynamic coefficient of friction, the macroscopic contact area of smooth and rough surfaces, the angle enclosed between the human finger and the soft-touch surfaces and the vibrations induced in the human finger during relative motion at a time. To validate the measurement stand, a test series has been conducted on two soft-touch surfaces of different roughness. While the individual results agree well with the literature, their combination revealed new insights. Finally, the investigation of the haptics of polymer coatings with the presented measuring system should facilitate the design of surfaces with tailor-made touch-feel properties.
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Delgadillo LE, Jones HL, Ismaily SK, Han S, Noble PC. How Flat Is the Tibial Osteotomy in Total Knee Arthroplasty? J Arthroplasty 2020; 35:870-6. [PMID: 31694778 DOI: 10.1016/j.arth.2019.10.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 09/19/2019] [Accepted: 10/03/2019] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Cementless total knee arthroplasty has been developed to decrease the incidence of failure in younger and more active patients. However, failures are still more common in cementless versus cemented components. It is hypothesized that this is triggered by incomplete bone-tray contact. The present study compares the final contact area of a cementless tray as a function of the initial osteotomy flatness. METHODS Eight surgeons prepared 14 cadaveric knees for cementless total knee replacement using standard instrumentation. The topography of each osteotomy was captured with a laser scanner; 3-dimensional computer models of the surfaces were generated. After scanning each tibia, the surgeons implanted cementless tibial trays using a manual impactor. Each tibia was then dissected, embedded in mounting resin, and sectioned. The sectioned blocks were observed under stereomicroscopy to identify points of bone-tray contact which were incorporated into the 3-dimensional models. Maps were then generated illustrating depicting contacting and noncontacting areas. RESULTS The mean initial flatness of all specimens was 1.1 ± 0.35 mm. After impaction, 79.4% ± 0.3% of the surface had established bony contact. Of the noncontacting areas, 17.6% were within 0.3 mm of the tray. Only 2.6% of the surface was at distances reported to impede ingrowth. Noncontacting areas were typically located centrally. A trend in decreasing percent contact area with increased flatness tolerance was observed (R2 = 0.605). CONCLUSION (1) There is an inverse correlation between the flatness of the tibial osteotomy and the percentage of the bony surface in contact with underside of the tibial tray. (2) Almost all tray-tibia contact is generated during implantation through flattening of elevated features on the tibial surface. (3) Gaps between the tray and the tibia are consistently located in the central regions of the osteotomy proximal to the medullary canal.
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Ambra LF, Mestriner AB, Ackermann J, Phan AT, Farr J, Gomoll AH. Bone-Plug Versus Soft Tissue Fixation of Medial Meniscal Allograft Transplants: A Biomechanical Study. Am J Sports Med 2019; 47:2960-2965. [PMID: 31454255 DOI: 10.1177/0363546519870179] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND It is controversial whether soft tissue fixation only and bone-plug techniques for medial meniscal allograft transplantation provide equivalent fixation and restoration of load distribution. Prior studies on this topic did not re-create the clinical situation with use of size-, side-, and compartment-matched meniscal transplants. HYPOTHESIS Both techniques will provide equivalent fixation of the meniscal transplant and restore load distribution and contact pressures similar to those of the native knee. STUDY DESIGN Controlled laboratory study. METHODS Nine fresh-frozen human cadaveric knees underwent mean contact pressure, mean contact area, and peak contact pressure evaluation in 4 medial meniscal testing conditions (native, total meniscectomy, bone-plug fixation, and soft tissue fixation) at 3 flexion angles (0°, 30°, and 60°) using Tekscan sensors under a 700-N axial load. RESULTS Medial meniscectomy resulted in significantly decreased contact area and increased contact pressure compared with the native condition at all flexion angles (P < .0001). Compared with the native state, soft tissue fixation demonstrated significantly higher mean contact pressure and lower mean contact area at 0° and 30° of flexion (P < .05), while bone-plug fixation showed no significant difference. There was no significant difference in peak contact pressure between study conditions. CONCLUSION Total medial meniscectomy leads to significantly worsened load distribution within the knee. Medial meniscal allograft transplantation can restore load parameters close to those of the native condition. The bone-plug technique demonstrated improved tibiofemoral contact pressures compared with soft tissue fixation. CLINICAL RELEVANCE Medial meniscal allograft transplantation with bone-plug fixation is a viable option to restore biomechanics in patients with meniscal deficiency.
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Affiliation(s)
- Luiz Felipe Ambra
- Departamento de Ortopedia e Traumatologia, Escola Paulista de Medicina/Universidade Federal de São Paulo, São Paulo, Brazil.,Center for Regenerative Medicine and Cartilage Repair Center, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Alexandre Barbieri Mestriner
- Departamento de Ortopedia e Traumatologia, Escola Paulista de Medicina/Universidade Federal de São Paulo, São Paulo, Brazil
| | - Jakob Ackermann
- Sports Medicine Center, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Amy T Phan
- Center for Regenerative Medicine and Cartilage Repair Center, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Jack Farr
- OrthoIndy and OrthoIndy Hospital, Greenwood and Indianapolis, Indiana, USA
| | - Andreas H Gomoll
- Department of Orthopedic Surgery, Hospital for Special Surgery, New York, New York, USA
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Gupta P, Zhang P, Sheriff J, Bluestein D, Deng Y. A Multiscale Model for Recruitment Aggregation of Platelets by Correlating with In Vitro Results. Cell Mol Bioeng 2019; 12:327-343. [PMID: 31662802 DOI: 10.1007/s12195-019-00583-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Introduction We developed a multiscale model to simulate the dynamics of platelet aggregation by recruitment of unactivated platelets flowing in viscous shear flows by an activated platelet deposited onto a blood vessel wall. This model uses coarse grained molecular dynamics (CGMD) for platelets at the microscale and dissipative particle dynamics (DPD) for the shear flow at the macroscale. Under conditions of relatively low shear, aggregation is mediated by fibrinogen via αIIbβ3 receptors. Methods The binding of αIIbβ3 and fibrinogen is modeled by a molecular-level hybrid force field consisting of Morse potential and Hooke law for the nonbonded and bonded interactions, respectively. The force field, parametrized in two different interaction scales, is calculated by correlating with the platelet contact area measured in vitro and the detaching force between αIIbβ3 and fibrinogen. Results Using our model, we derived, the relationship between recruitment force and distance between the centers of mass of two platelets, by integrating the molecular-scale inter-platelet interactions during recruitment aggregation in shear flows. Our model indicates that assuming a rigid-platelet model, underestimates the contact area by 89% and the detaching force by 93% as compared to a model that takes into account the platelet deformability leading to a prediction of a significantly lower attachment during recruitment. Conclusions The molecular-level predictive capability of our model sheds a light on differences observed between transient and permanent platelet aggregation patterns. The model and simulation framework can be further adapted to simulate initial thrombus formation involving multiple flowing platelets as well as deposition and adhesion onto blood vessels.
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Affiliation(s)
- Prachi Gupta
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY 11794-3600 USA
| | - Peng Zhang
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794 USA
| | - Jawaad Sheriff
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794 USA
| | - Danny Bluestein
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794 USA
| | - Yuefan Deng
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY 11794-3600 USA
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Chen X, Hu H, Trasobares J, Nijhuis CA. Rectification Ratio and Tunneling Decay Coefficient Depend on the Contact Geometry Revealed by in Situ Imaging of the Formation of EGaIn Junctions. ACS Appl Mater Interfaces 2019; 11:21018-21029. [PMID: 31117425 DOI: 10.1021/acsami.9b02033] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
This paper describes how the intensive (tunneling decay coefficient β and rectification ratio R) and extensive (current density J) properties of Ag-S(CH2) n-1CH3//GaO x/EGaIn junctions ( n = 10, 14, 18) and molecular diodes of the form of Ag-S(CH2)11Fc//GaO x/EGaIn depend on Ageo, the contact area between the self-assembled monolayer and the cone-shaped EGaIn tip. Large junctions with Ageo ≥ 1000 μm2 are unreliable and defects, such as pinholes, dominate the charge transport characteristics. For S(CH2)11Fc SAMs, R decreases from 130 to unity with increasing Ageo due to an increase in the leakage current (the current flowing across the junction at reverse bias when the diodes block current flow). The value of β decreases from 1.00 ± 0.06 n-1 to 0.70 ± 0.03 n-1 with increasing Ageo which also indicates that large junctions suffer from defects. Small junctions with Ageo ≤ 300 μm2 are not stable due to the high surface tension of the bulk EGaIn resulting in unstable EGaIn tips. In addition, the contact area for such small junctions is dominated by the rough tip apex reducing the effective contact area and reproducibility significantly. The contact area of very large junctions is dominated by the relatively smooth side walls of the tips. Our findings show that there is an optimum range for the value of Ageo between 300-500 μm2 where the electrical properties of the junctions are dominated by molecular effects. In this range of Ageo, the value of J (defined by I/ Ageo where I is the measured current) increases with Ageo until it plateaus for junctions with Ageo > 1000 μm2 in agreement with recently reported findings by the Whitesides group. In this regime reproducible measurements of J can be obtained provided Ageo is kept constant.
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Affiliation(s)
- Xiaoping Chen
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , Singapore 117543 , Singapore
| | - Hongting Hu
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , Singapore 117543 , Singapore
| | - Jorge Trasobares
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , Singapore 117543 , Singapore
| | - Christian A Nijhuis
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , Singapore 117543 , Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , 6 Science Drive 2 , Singapore 117546 , Singapore
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Park J, Kim T. Acute effect of taping on plantar pressure characteristics in athletes with exercise-induced leg pain: a description and comparison of groups. PHYSICIAN SPORTSMED 2019; 47:212-219. [PMID: 30462925 DOI: 10.1080/00913847.2018.1547085] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
OBJECTIVES Foot pronation is considered as a potential risk factor of lower leg overuse injury. This study aimed to identify plantar pressure characteristics of elite athletes with exercise-induced leg pain in throwing athletic disciplines, and to verify the acute effect of taping for restricting foot pronation by analyzing the plantar pressure characteristics. METHODS This study was designed as a description and comparison of throwing athletic athletes. Participants were divided into exercise-induced leg pain (ELP group, n = 17) and control groups (CON group, n = 14). Plantar pressure variables (contact area, maximum force, and peak pressure) at eight-foot regions in athletes' supporting leg were recorded during standing on one leg and a natural walk before and after applying anti-pronation or sham taping techniques. RESULTS There are significant difference of contact area, maximal force, and peak pressure in some regions of their foot between the ELP and CON groups. But the anti-pronation taping decreased only the peak pressure in lateral midfoot of CON group during a natural walk (p = 0.002). CONCLUSION The anti-pronation taping technique may not be effective preventive strategy from the exercise-induced leg pain, such as shin splints.
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Affiliation(s)
- JaeMyoung Park
- a Research Institute of Physical Education and Sport Science , Korea National Sport University , Seoul , Republic of Korea
| | - Taegyu Kim
- b Department of Marine Sports , Pukyoung National University , Busan , Republic of Korea
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Chander NG, Biswas A. Clinical evaluation of differences in proximal contact strength of various fixed dental prosthesis materials. Indian J Dent Res 2019; 29:739-743. [PMID: 30589001 DOI: 10.4103/ijdr.ijdr_21_18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Objective The study compared the proximal contact strength (CS) of different fixed dental prosthesis (FDP) materials. Materials and Methods Thirty volunteers participated in this study with definitive inclusion and exclusion criteria. Participants were divided into full metal, zirconia, and metal ceramic groups. The CS between the natural teeth and the maxillary posterior quadrant FDP was measured with force gauge. The data were evaluated with one-way analysis of variance test, and Tukey's honest significant difference post hoc was done to compare the mean values. Paired samples t-test was used to compare the mean values between pre- and postoperative CS. Results The postoperative CS observed in the full metal group in premolar was 0.320 ± 0.1092 N and in second molar was 0.385 ± 0.1130 N. CS obtained with zirconia FDP in both premolar (0.679 ± 0.0927 N) and molar (0.770 ± 0.0960 N) was highest among all groups. The results were statistically significant (P < 0.001). Conclusion Postoperative CS was greater in zirconia when compared with metal and metal ceramic FDP. Clinical Relevance FDP materials had acceptable CS. Zirconia is preferable for optimal CS.
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Affiliation(s)
- N Gopi Chander
- Department of Prosthodontics, SRM Dental College, Chennai, Tamil Nadu, India
| | - Arnob Biswas
- Department of Prosthodontics, SRM Dental College, Chennai, Tamil Nadu, India
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Lange T, Taghizadeh E, Knowles BR, Südkamp NP, Zaitsev M, Meine H, Izadpanah K. Quantification of patellofemoral cartilage deformation and contact area changes in response to static loading via high-resolution MRI with prospective motion correction. J Magn Reson Imaging 2019; 50:1561-1570. [PMID: 30903682 DOI: 10.1002/jmri.26724] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 02/26/2019] [Accepted: 02/26/2019] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Higher-resolution MRI of the patellofemoral cartilage under loading is hampered by subject motion since knee flexion is required during the scan. PURPOSE To demonstrate robust quantification of cartilage compression and contact area changes in response to in situ loading by means of MRI with prospective motion correction and regularized image postprocessing. STUDY TYPE Cohort study. SUBJECTS Fifteen healthy male subjects. FIELD STRENGTH 3 T. SEQUENCE Spoiled 3D gradient-echo sequence augmented with prospective motion correction based on optical tracking. Measurements were performed with three different loads (0/200/400 N). ASSESSMENT Bone and cartilage segmentation was performed manually and regularized with a deep-learning approach. Average patellar and femoral cartilage thickness and contact area were calculated for the three loading situations. Reproducibility was assessed via repeated measurements in one subject. STATISTICAL TESTS Comparison of the three loading situations was performed by Wilcoxon signed-rank tests. RESULTS Regularization using a deep convolutional neural network reduced the variance of the quantified relative load-induced changes of cartilage thickness and contact area compared to purely manual segmentation (average reduction of standard deviation by ∼50%) and repeated measurements performed on the same subject demonstrated high reproducibility of the method. For the three loading situations (0/200/400 N), the patellofemoral cartilage contact area as well as the mean patellar and femoral cartilage thickness were significantly different from each other (P < 0.05). While the patellofemoral cartilage contact area increased under loading (by 14.5/19.0% for loads of 200/400 N), patellar and femoral cartilage thickness exhibited a load-dependent thickness decrease (patella: -4.4/-7.4%, femur: -3.4/-7.1% for loads of 200/400 N). DATA CONCLUSION MRI with prospective motion correction enables quantitative evaluation of patellofemoral cartilage deformation and contact area changes in response to in situ loading. Regularizing the manual segmentations using a neural network enables robust quantification of the load-induced changes. LEVEL OF EVIDENCE 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:1561-1570.
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Affiliation(s)
- Thomas Lange
- Department of Radiology, Medical Physics, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Elham Taghizadeh
- Medical Image Computing Group, Department of Informatics, University of Bremen, Germany.,Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany
| | - Benjamin R Knowles
- Department of Radiology, Medical Physics, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Norbert P Südkamp
- Department of Orthopedic and Trauma Surgery, Medical Center - Albert-Ludwigs-University of Freiburg, Faculty of Medicine, Albert-Ludwigs-University of Freiburg, Freiburg im Breisgau, Germany
| | - Maxim Zaitsev
- Department of Radiology, Medical Physics, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Hans Meine
- Medical Image Computing Group, Department of Informatics, University of Bremen, Germany.,Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany
| | - Kaywan Izadpanah
- Department of Orthopedic and Trauma Surgery, Medical Center - Albert-Ludwigs-University of Freiburg, Faculty of Medicine, Albert-Ludwigs-University of Freiburg, Freiburg im Breisgau, Germany
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Sahara W, Yamazaki T, Konda S, Sugamoto K, Yoshikawa H. Influence of humeral abduction angle on axial rotation and contact area at the glenohumeral joint. J Shoulder Elbow Surg 2019; 28:570-7. [PMID: 30573432 DOI: 10.1016/j.jse.2018.08.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 08/10/2018] [Accepted: 08/19/2018] [Indexed: 02/01/2023]
Abstract
BACKGROUND Although the elevation angle of the arm affects the range of rotation, it has not been evaluated up to the maximal abduction angle. In this study we conducted an evaluation up to maximal abduction and determined the contact patterns at the glenohumeral (GH) joint. METHODS Fourteen healthy volunteers (12 men and 2 women; mean age, 26.9 years) with normal shoulders (14 right and 8 left) were instructed to rotate their shoulders at 0°, 90°, 135°, and maximal abduction for each shoulder at a time. Using 2-dimensional and 3-dimensional single-plane image registration, the internal rotation (IR), external rotation (ER), and range of motion (ROM; ie, axial rotations) at the thoracohumeral (TH) and GH joints, and the contribution ratio (%ROM = GH-ROM/TH-ROM) were calculated for each abduction. The glenoid position with respect to the humeral head was also analyzed. RESULTS The TH-IR and TH-ER shifted toward an ER with increasing abduction angle, whereas the TH-ROM significantly decreased except at abduction between 0° and 90° (P < .001). The GH-IR and GH-ROM significantly decreased except at abduction between 0° and 90° (P < .001), but the GH-ER remained constant regardless of the abduction. The contribution ratio exceeded 80% for every abduction angle. The glenoid moved on the central and posterior areas of the humeral head at 0° and 90° abduction, respectively, and on the posterosuperior and anterosuperior areas at 135° and maximal abduction, respectively. CONCLUSION Our results provide new knowledge about wide axial rotation up to maximal abduction and constant GH-ER at any abduction.
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Willinger L, Foehr P, Achtnich A, Forkel P, Voss A, Liska F, Lacheta L, Imhoff AB, Burgkart R. Effect of Lower Limb Alignment in Medial Meniscus-Deficient Knees on Tibiofemoral Contact Pressure. Orthop J Sports Med 2019; 7:2325967118824611. [PMID: 30800688 PMCID: PMC6378645 DOI: 10.1177/2325967118824611] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Background: Degenerative medial meniscal tears and subsequent partial meniscal resection compromise meniscal function and lead to an overload of the medial compartment. In addition, lower limb alignment plays a key role in load distribution between the medial and lateral knee compartments, and varus alignment is a potential risk factor for medial osteoarthritis. Purpose/Hypothesis: The purpose of this biomechanical study was to investigate the effect of valgus and varus alignment on peak pressure and contact area in knees with concomitant horizontal medial meniscal tears and subsequent leaflet resection. It was hypothesized that varus alignment in combination with meniscal loss leads to the highest peak pressure within the medial compartment. Study Design: Controlled laboratory study. Methods: Six fresh-frozen human cadaveric knees were axially loaded using a 1000-N compressive load in full extension with the mechanical axis rotated to intersect the tibial plateau at 40%, 45%, 50%, 55%, and 60% of its width (TPW) to simulate varus and valgus alignment. Tibiofemoral peak contact pressure and contact area of the medial and lateral compartments were determined using pressure-sensitive foils in each of 4 different meniscal conditions: intact, 15-mm horizontal tear of the posterior horn, inferior leaflet resection, and resection of both leaflets. Results: The effect of alignment on peak pressure (normalized to the neutral axis) within the medial compartment in cases of an intact meniscus was measured as follows: varus shift resulted in a mean increase in peak pressure of 18.5% at 45% of the TPW and 37.4% at 40% of the TPW, whereas valgus shift led to a mean decrease in peak pressure of 8.7% at 55% of the TPW and 23.1% at 60% of the TPW. Peak pressure changes between the intact meniscus and resection within the medial compartment was less in valgus-aligned knees (0.21 MPa at 60% TPW, 0.59 MPa at 50% TPW, and 0.76 MPa at 40% TPW). Contact area was significantly reduced after partial meniscal resection in the neutral axis (intact, 553.5 ± 87.6 mm2; resection of both leaflets, 323.3 ± 84.2 mm2; P < .001). This finding was consistent in any alignment. Conclusion: Both partial medial meniscal resection and varus alignment led to an increase in medial compartment peak pressure. Valgus alignment prevented medial overloading by decreasing contact pressure even after partial meniscal resection. A horizontal meniscal tear did not influence peak pressure and contact area even in varus alignment. Clinical Relevance: As a clinical consequence, partial meniscal resection should be avoided to maintain the original biomechanical behavior, and the mechanical axis should be taken into account if partial meniscectomy is necessary.
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Affiliation(s)
- Lukas Willinger
- Department of Orthopaedic Sports Medicine, Rechts der Isar Hospital, Technical University of Munich, Munich, Germany
| | - Peter Foehr
- Department of Orthopedics and Sports Orthopedics, Rechts der Isar Hospital, Technical University of Munich, Munich, Germany
| | - Andrea Achtnich
- Department of Orthopaedic Sports Medicine, Rechts der Isar Hospital, Technical University of Munich, Munich, Germany
| | - Philipp Forkel
- Department of Orthopaedic Sports Medicine, Rechts der Isar Hospital, Technical University of Munich, Munich, Germany
| | - Andreas Voss
- Department of Orthopaedic Sports Medicine, Rechts der Isar Hospital, Technical University of Munich, Munich, Germany.,Department of Trauma Surgery, University Hospital Regensburg, Regensburg, Germany
| | - Franz Liska
- Department of Orthopaedic Sports Medicine, Rechts der Isar Hospital, Technical University of Munich, Munich, Germany
| | - Lucca Lacheta
- Department of Orthopaedic Sports Medicine, Rechts der Isar Hospital, Technical University of Munich, Munich, Germany
| | - Andreas B Imhoff
- Department of Orthopaedic Sports Medicine, Rechts der Isar Hospital, Technical University of Munich, Munich, Germany
| | - Rainer Burgkart
- Department of Orthopedics and Sports Orthopedics, Rechts der Isar Hospital, Technical University of Munich, Munich, Germany
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Yuan XN, Liang WD, Zhou FH, Li HT, Zhang LX, Zhang ZQ, Li JJ. Comparison of walking quality variables between incomplete spinal cord injury patients and healthy subjects by using a footscan plantar pressure system. Neural Regen Res 2019; 14:354-360. [PMID: 30531020 PMCID: PMC6301183 DOI: 10.4103/1673-5374.244798] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The main goal of spinal cord rehabilitation is to restore walking ability and improve walking quality after spinal cord injury (SCI). The spatiotemporal parameters of walking and the parameters of plantar pressure can be obtained using a plantar pressure analysis system. Previous studies have reported step asymmetry in patients with bilateral SCI. However, the asymmetry of other parameters in patients with SCI has not been reported. This was a prospective, cross-sectional study, which included 23 patients with SCI, aged 48.1 ± 14.5 years, and 28 healthy subjects, aged 47.1 ± 9.8 years. All subjects underwent bare foot walking on a plantar pressure measurement device to measure walking speed and spatiotemporal parameters. Compared with healthy subjects, SCI patients had slower walking speed, longer stride time and stance time, larger stance phase percentage, and shorter stride length. The peak pressures under the metatarsal heads and toe were lower in SCI patients than in healthy subjects. In the heel, regional impulse and the contact area percentage in SCI patients were higher than those in healthy subjects. The symmetry indexes of stance time, step length, maximum force, impulse and contact area were increased in SCI patients, indicating a decline in symmetry. The results confirm that the gait quality, including spatiotemporal variables and plantar pressure parameters, and symmetry index were lower in SCI patients compared with healthy subjects. Plantar pressure parameters and symmetry index could be sensitive quantitative parameters to improve gait quality of SCI patients. The protocols were approved by the Clinical Research Ethics Committee of Shengjing Hospital of China Medical University (approval No. 2015PS54J) on August 13, 2015. This trial was registered in the ISRCTN Registry (ISRCTN42544587) on August 22, 2018. Protocol version 1.0.
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Affiliation(s)
- Xiang-Nan Yuan
- Rehabilitation Department, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, China
| | - Wei-Di Liang
- Rehabilitation Department, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, China
| | - Feng-Hua Zhou
- Rehabilitation Department, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, China
| | - Han-Ting Li
- Rehabilitation Department, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, China
| | - Li-Xin Zhang
- Rehabilitation Department, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, China
| | - Zhi-Qiang Zhang
- Rehabilitation Department, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, China
| | - Jian-Jun Li
- Department of Orthopedics, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, China
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Liu N, Yu R. Investigation of force, contact area and dwell time in finger-tapping tasks on membrane touch interface. Ergonomics 2018; 61:1519-1529. [PMID: 29856276 DOI: 10.1080/00140139.2018.1484178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 05/20/2018] [Indexed: 06/08/2023]
Abstract
This study aimed to determine the touch characteristics during tapping tasks on membrane touch interface and investigate the effects of posture and gender on touch characteristics variables. One hundred participants tapped digits displayed on a membrane touch interface on sitting and standing positions using all fingers of the dominant hand. Touch characteristics measures included average force, contact area and dwell time. Across fingers and postures, males exerted larger force and contact area than females, but similar dwell time. Across genders and postures, thumb exerted the largest force and the force of the other four fingers showed no significant difference. The contact area of the thumb was the largest, whereas that of the little finger was the smallest; the dwell time of the thumb was the longest, whereas that of the middle finger was the shortest. Relationships among finger sizes, gender, posture and touch characteristics were proposed. The findings helped direct membrane touch interface design for digital and numerical control products from hardware and software perspectives. Practitioner Summary: This study measured force, contact area and dwell time in tapping tasks on membrane touch interface and examined effects of gender and posture on force, contact area and dwell time. The findings will direct membrane touch interface design for digital and numerical control products from hardware and software perspectives. Abbreviations: M: mean; SD: standard deviation; ISO: International Organization for Standardization; LCD: liquid crystal display; ANOVA: analysis of variance; ANSI: American National Standards Institute; HFES: Human Factors and Ergonomics Society.
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Affiliation(s)
- Na Liu
- a Department of Industrial Engineering , Tsinghua University , Beijing , China
| | - Ruifeng Yu
- a Department of Industrial Engineering , Tsinghua University , Beijing , China
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Yang JH, Park HJ, Jang HD, Lee SJ. Measurement of cooked rice stickiness with consideration of contact area in compression test. J Texture Stud 2018; 49:639-645. [PMID: 30264394 DOI: 10.1111/jtxs.12370] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 04/16/2018] [Accepted: 06/05/2018] [Indexed: 11/29/2022]
Abstract
The cooked rice stickiness is conventionally measured as the maximum detachment force required to separate the probe from the sample, after compression on the platform of a texture analyzer. A corrected stickiness (the measured stickiness force divided by the contact area) was newly created to avoid the deviation of stickiness influenced by the contact area varying with the rice sample's irregularity, regarding shape and size. The contact area could be estimated from the volume, density, and thickness of the samples. The compression force triggering the stickiness was also converted to the corrected compression force (the force divided by the contact area). Two varieties of rice (short-grain rice and glutinous rice) were cooked with different amount of water to prepare the samples with various stickiness levels. The contact area was mostly higher in the glutinous rice than short-grain rice. The contact area increased with the cooking water amount. Three parameters were compared such as the stickiness (the measured force), the primarily corrected stickiness (the corrected stickiness at a fixed value of compression force), and the secondarily corrected stickiness (the corrected stickiness at a fixed value of the corrected compression force). The difference between the rice samples was the most pronounced in the secondarily corrected stickiness. The correlation between the instrumental and sensorial stickiness was also the highest in the secondarily corrected stickiness. Conclusively, the new corrected parameters enhanced the sample discrimination capability and the agreement with the sensorial stickiness than the uncorrected stickiness. PRACTICAL APPLICATIONS: Stickiness is the important quality factor associated with cooked rice preferences. Instrumental stickiness is a detaching force of the preliminarily compressed rice grain by cylindrical probe of texture testing equipment. When it comes to a force measurement, the contact area is usually considered to convert the force to stress. But, for the samples like cooked rice grain, with smaller contact area than that of probe, the contact area is not easy to know because it is not simply the probe bottom area. So the contact area had not been employed to measure cooked rice stickiness. In this study, an established method was devised to figure out the contact area. The corrected stickiness by considering the contact area proved to be more accurate than the original stickiness through sensory evaluation.
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Affiliation(s)
- Jung Hwa Yang
- Department of Food Science and Biotechnology, Dongguk University-Seoul, Goyang-si, Republic of Korea
| | - Han Jo Park
- Department of Food Science and Biotechnology, Dongguk University-Seoul, Goyang-si, Republic of Korea
| | - Han Dong Jang
- Department of Food Science and Biotechnology, Dongguk University-Seoul, Goyang-si, Republic of Korea
| | - Seung Ju Lee
- Department of Food Science and Biotechnology, Dongguk University-Seoul, Goyang-si, Republic of Korea
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Hwang JT, Kim Y, Bachman DR, Shields MN, Berglund LJ, Fitzsimmons AT, Fitzsimmons JS, O'Driscoll SW. Axial load transmission through the elbow during forearm rotation. J Shoulder Elbow Surg 2018; 27:530-537. [PMID: 29290603 DOI: 10.1016/j.jse.2017.10.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 10/09/2017] [Accepted: 10/18/2017] [Indexed: 02/01/2023]
Abstract
BACKGROUND Forearm rotation is closely associated with the axiorotational force transmission through the elbow joint. A technique has been developed to study the transmission of force across the radiocapitellar and ulnotrochlear joints during forearm rotation. METHODS Ten human cadaveric upper limbs were prepared on a custom-designed apparatus that permits the application of extrinsic axial loads across an intact cadaveric elbow joint. A force-sensitive transducer was inserted into the elbow joint of each cadaver. A 160 N axial force was applied to the specimen during cyclic forearm rotation while the force, contact pressure, and contact area through the elbow joint were measured. RESULTS The mean force across the radiocapitellar joint showed no significant difference between pronation and supination (P = .3547). The radiocapitellar joint showed significantly higher contact area (P = .0001) and lower contact pressure (P = .0001) in pronation than in supination. The mean values for contact pressure, area, and force across the ulnotrochlear joint were not significantly different between supination and pronation. CONCLUSION The contact pressure and contact area of the radiocapitellar joint in the cadaveric model changed according to forearm rotation while the force remained constant. The mean contact pressure of the radiocapitellar joint in pronation was significantly lower than that in supination because the force across it did not change significantly and its contact area decreased significantly. These findings may suggest that the pronated elbow can play an important role in protecting the radiocapitellar joint in high-impact activities like delivering punch in martial arts or falling on an outstretched arm.
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Affiliation(s)
- Jung-Taek Hwang
- Department of Orthopedics, Biomechanics Laboratory, Mayo Clinic, Rochester, MN, USA; Department of Orthopedic Surgery, Chuncheon Sacred Heart Hospital, Hallym University Medical College, Chuncheon, Republic of Korea
| | - Youngbok Kim
- Department of Orthopedics, Biomechanics Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Daniel R Bachman
- Department of Orthopedics, Biomechanics Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Maegan N Shields
- Department of Orthopedics, Biomechanics Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Lawrence J Berglund
- Department of Orthopedics, Biomechanics Laboratory, Mayo Clinic, Rochester, MN, USA
| | | | - James S Fitzsimmons
- Department of Orthopedics, Biomechanics Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Shawn W O'Driscoll
- Department of Orthopedics, Biomechanics Laboratory, Mayo Clinic, Rochester, MN, USA.
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Kong X, Zhu W, Cao L, Peng Y, Shen S, Deng Y. Controllable Electrical Contact Resistance between Cu and Oriented-Bi 2Te 3 Film via Interface Tuning. ACS Appl Mater Interfaces 2017; 9:25606-25614. [PMID: 28691488 DOI: 10.1021/acsami.7b05460] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The contact resistance between metals and semiconductors has become critical for the design of thin-film thermoelectric devices with their continuous miniaturization. Herein, we report a novel interface tuning method to regulate the contact resistance at the Bi2Te3-Cu interface, and three Bi2Te3 films with different oriented microstructures are obtained. The lowest contact resistivity (∼10-7 Ω cm2) is observed between highly (00l) oriented Bi2Te3 and Cu film, nearly an order of magnitude lower than other orientations. This significant decrease of contact resistivity is attributed to the denser film connections, lower lattice misfit, larger effective conducting contact area, and smaller width of the surface depletion region. Meanwhile, our results show that the reduction of contact resistance has little dependence on the interfacial diffusion based on the little change in contact resistivity after the introduction of an effective Ti barrier layer. Our work provides a new idea for the mitigation of contact resistivity in thin-film thermoelectric devices and also gives certain guidance for the size design of the next-level miniaturized devices.
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Affiliation(s)
- Xixia Kong
- School of Materials Science and Engineering, Beihang University , Beijing 100191, China
| | - Wei Zhu
- School of Materials Science and Engineering, Beihang University , Beijing 100191, China
| | - Lili Cao
- School of Materials Science and Engineering, Beihang University , Beijing 100191, China
| | - Yuncheng Peng
- School of Materials Science and Engineering, Beihang University , Beijing 100191, China
| | - Shengfei Shen
- School of Materials Science and Engineering, Beihang University , Beijing 100191, China
| | - Yuan Deng
- School of Materials Science and Engineering, Beihang University , Beijing 100191, China
- Beijing Key Laboratory for Advanced Functional Materials and Thin Film Technology , Beijing 100191, China
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Lee SM, Oh S, Yu SJ, Lee KM, Son SA, Kwon YH, Kim YI. Association between brain lateralization and mixing ability of chewing side. J Dent Sci 2017; 12:133-138. [PMID: 30895038 PMCID: PMC6395226 DOI: 10.1016/j.jds.2016.09.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 09/18/2016] [Indexed: 11/30/2022] Open
Abstract
Background/purpose Previous studies have suggested that functional dominance in one part of the body can be correlated with functional dominance in another part. Thus, the present research aimed to determine whether brain laterality (handedness, footedness, earedness, and eyedness) was related to mixing ability and chewing side preference. Materials and methods Fifty-four volunteers who were not undergoing any form of dental treatment took part in this study. Self-defined brain laterality was determined through a questionnaire. The volunteers performed five tasks related to brain laterality, which was identified by the side used to perform three or more of the five tasks. Chewing side preference was determined by observing the main gum location on the occlusal area when volunteers chewed for 30 strokes. Mixing Ability Index (MAI) was measured by analyzing the degree of mixing of two differently colored waxes (height, 3 mm; diameter, 20 mm). Occlusion contact area was measured by taking the maximum intercuspation bite with polysiloxane. Results Thirty-nine volunteers (72%) showed significant agreement between brain dominance and chewing preference side. The association between brain dominance and MAI was not significant. The occlusal contact area of the dominant side (mean = 48.2 mm2) was significantly wider than that of the nondominant side (25.7 mm2). Conclusion Brain laterality can be explained by the side of functional (preference of the hands, eyes, ears, and feet, and survey) has a positive correlation with chewing preference side. MAI between the brain dominant and nondominant sides was not significant. This shows that mastication efficiency does not differ between dominant and nondominant sides. So, this study suggests that brain dominance is correlated with chewing preference, but it does not affect efficiency of mastication.
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Affiliation(s)
- Seung-Min Lee
- Dental Research Institute, Pusan National University Dental Hospital, Yangsan, South Korea
| | - Sewoong Oh
- Dental Research Institute, Pusan National University Dental Hospital, Yangsan, South Korea
| | - Sung Jin Yu
- Dental Research Institute, Pusan National University Dental Hospital, Yangsan, South Korea
| | - Kyung-Min Lee
- Department of Orthodontics, School of Dentistry, Chonnan National University, Gwangju, South Korea
| | - Sung-Ae Son
- Department of Conservative Dentistry, Pusan National University Dental Hospital, Yangsan, South Korea
| | - Young Hoon Kwon
- Department of Dental Materials, Pusan National University, Yangsan, South Korea
| | - Yong-Il Kim
- Dental Research Institute, Pusan National University Dental Hospital, Yangsan, South Korea.,Biomedical Research Institute, Pusan National University Hospital, Busan, South Korea.,Institute of Translational Dental Sciences, Pusan National University, Yangsan, South Korea
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Liu X, Carré MJ, Zhang Q, Lu Z, Matcher SJ, Lewis R. Measuring contact area in a sliding human finger-pad contact. Skin Res Technol 2017; 24:31-44. [PMID: 28573767 DOI: 10.1111/srt.12387] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/26/2017] [Indexed: 11/26/2022]
Abstract
BACKGROUND/PURPOSE The work outlined in this paper was aimed at achieving further understanding of skin frictional behaviour by investigating the contact area between human finger-pads and flat surfaces. METHODS Both the static and the dynamic contact areas (in macro- and micro-scales) were measured using various techniques, including ink printing, optical coherence tomography (OCT) and Digital Image Correlation (DIC). RESULTS In the studies of the static measurements using ink printing, the experimental results showed that the apparent and the real contact area increased with load following a piecewise linear correlation function for a finger-pad in contact with paper sheets. Comparisons indicated that the OCT method is a reliable and effective method to investigate the real contact area of a finger-pad and allow micro-scale analysis. The apparent contact area (from the DIC measurements) was found to reduce with time in the transition from the static phase to the dynamic phase while the real area of contact (from OCT) increased. CONCLUSIONS The results from this study enable the interaction between finger-pads and contact object surface to be better analysed, and hence improve the understanding of skin friction.
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Affiliation(s)
- X Liu
- The Department of Mechanical Engineering, The University of Sheffield, Sheffield, UK
| | - M J Carré
- The Department of Mechanical Engineering, The University of Sheffield, Sheffield, UK
| | - Q Zhang
- The Department of Electronic and Electrical Engineering, Liverpool John Moores University, Liverpool, UK
| | - Z Lu
- The Department of Electronic and Electrical Engineering, The University of Sheffield, Sheffield, UK
| | - S J Matcher
- The Department of Electronic and Electrical Engineering, The University of Sheffield, Sheffield, UK
| | - R Lewis
- The Department of Mechanical Engineering, The University of Sheffield, Sheffield, UK
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Lv H, Guo Y, Wu G, Ji G, Zhao Y, Xu ZJ. Interface Polarization Strategy to Solve Electromagnetic Wave Interference Issue. ACS Appl Mater Interfaces 2017; 9:5660-5668. [PMID: 28116900 DOI: 10.1021/acsami.6b16223] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Design of an interface to arouse interface polarization is an efficient route to attenuate high-frequency electromagnetic waves. The attenuation intensity is highly related to the contact area. To achieve stronger interface polarization, growing metal oxide granular film on graphene with a larger surface area seems to be an efficient strategy due to the high charge carrier concentration of graphene. This study is devoted to fabricating the filmlike composite by a facile thermal decomposition method and investigating the relationship among contact area, polarization intensity, and the type of metal oxide. Because of the high-frequency polarization effect, the composites presented excellent electromagnetic wave attenuation ability. It is shown that the optimal effective frequency bandwidth of graphene/metal oxide was close to 7.0 GHz at a thin coating layer of 2.0 mm. The corresponding reflection loss value was nearly -22.1 dB. Considering the attenuation mechanism, interface polarization may play a key role in the microwave-absorbing ability.
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Affiliation(s)
- Hualiang Lv
- College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics , Nanjing 211100, PR China
- School of Materials Sciences and Engineering, Nanyang Technological University , 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Yuhang Guo
- School of Materials Science and Engineering, Jiangsu University of Science and Technology , Zhenjiang, Jiangsu 212003, China
| | - Guanglei Wu
- Institute of Materials for Energy and Environment, State Key Laboratory Breeding Base of New Fiber Materials and Modern Textile, College of Materials Science and Engineering, Qingdao University , Qingdao 266071, PR China
| | - Guangbin Ji
- College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics , Nanjing 211100, PR China
| | - Yue Zhao
- College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics , Nanjing 211100, PR China
| | - Zhichuan J Xu
- School of Materials Sciences and Engineering, Nanyang Technological University , 50 Nanyang Avenue, Singapore 639798, Singapore
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Flessner MF. Pharmacokinetic problems in peritoneal drug administration: an update after 20 years. Pleura Peritoneum 2016; 1:183-191. [PMID: 30911622 DOI: 10.1515/pp-2016-0022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 11/29/2016] [Indexed: 12/14/2022] Open
Abstract
Intraperitoneal chemotherapy has demonstrated significant pharmacologic and clinical advantage over traditional intravenous administration for cancers that are restricted to the peritoneal cavity. The combination of cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC) has become the standard technique used to fight ovarian and gastrointestinal cancers in many centers. However, challenges remain for HIPEC to contact the entire peritoneal surface, penetrate the tumor tissue, and transport to the lymphatics and other metastatic sites. New innovations in delivery technique, such as heated aerosol, and in delivery molecules, such as microparticles, nanoparticles, nanogels, and tumor-penetrating peptides are being tested in animal models and will likely soon be in human trials. Improvements in overall care, such as the recent clinical trial of an oral agent for maintenance therapy in ovarian carcinoma, will continue in this field for the next 20 years.
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Abstract
BACKGROUND In 1976, Ramsey and Hamilton published a landmark cadaveric study demonstrating a dramatic 42% decrease in tibiotalar contact area with only 1 mm of lateral talar shift. An increase in maximum principal stress of at least 72% is predicted based on these findings though the delayed development of arthritis in minimally misaligned ankles does not appear to be commensurate with the results found in dry cadaveric models. We hypothesized that synovial fluid could be a previously unrecognized factor that contributes significantly to stress distribution in the tibiotalar joint in anatomic and injured states. METHODS As it is not possible to directly measure contact stresses with and without fluid in a cadaveric model, finite element analysis (FEA) was employed for this study. FEA is a modeling technique used to calculate stresses in complex geometric structures by dividing them into small, simple components called elements. Four test configurations were investigated using a finite element model (FEM): baseline ankle alignment, 1 mm laterally translated talus and fibula, and the previous 2 bone orientations with fluid added. The FEM selected for this study was the Global Human Body Models Consortium-owned GHBMC model, M50 version 4.2, a model of an average-sized male (distributed by Elemance, LLC, Winston-Salem, NC). The ankle was loaded at the proximal tibia with a distributed load equal to the GHBMC body weight, and the maximum principal stress was computed. RESULTS All numerical simulations were stable and completed with no errors. In the baseline anatomic configuration, the addition of fluid between the tibia, fibula, and talus reduced the maximum principal stress computed in the distal tibia at maximum load from 31.3 N/mm2 to 11.5 N/mm2. Following 1 mm lateral translation of the talus and fibula, there was a modest 30% increase in the maximum stress in fluid cases. Qualitatively, translation created less high stress locations on the tibial plafond when fluid was incorporated into the model. CONCLUSIONS The findings in this study demonstrate a meaningful role for synovial fluid in distributing stresses within the ankle that has not been considered in historical dry cadaveric studies. The increase in maximum stress predicted by simulation of an ankle with fluid was less than half that projected by cadaveric data, indicating a protective effect of fluid in the injured state. The trends demonstrated by these simulations suggest that bony alignment and fluid in the ankle joint change loading patterns on the tibia and should be accounted for in future experiments. CLINICAL RELEVANCE Synovial fluid may play a protective role in ankle injuries, thus delaying the onset of arthritis. Reactive joint effusions may also function to additionally redistribute stresses with higher volumes of viscous fluid.
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Affiliation(s)
| | - Aaron T Scott
- Wake Forest School of Medicine, Winston-Salem, NC, USA
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Abstract
BACKGROUND Horizontal, degenerative tears of the medial meniscus and subsequent meniscectomy can compromise the biomechanical function of the meniscus in load transmission and weightbearing, leading to the development of radiographic and symptomatic tibiofemoral arthritis. HYPOTHESIS Resection of both leaflets of a horizontal medial meniscal tear will increase peak contact pressures and decrease contact areas in comparison with resection of only the inferior leaflet. STUDY DESIGN Controlled laboratory study. METHODS Twelve fresh-frozen human cadaveric knees had tibiofemoral peak contact pressures and contact areas under an 1800-N axial load measured by Tekscan in the control state. A horizontal tear was created in the posterior horn of the medial meniscus, and the knees were retested. The knees were tested a third time after resection of the inferior leaflet (single leaflet) and a final time after resection of the superior leaflet (both leaflets). The Friedman test was used to test for group differences in peak pressure (psi) and contact area (mm(2)) between test conditions (native, tear, inferior leaflet resection, and resection of both leaflets). RESULTS For the medial compartment, there was a statistically significant difference in peak pressure (P = .03) but not in contact area (P = .70) between testing conditions. Median peak pressure in the medial compartment was significantly greater for resection of both leaflets compared with the tear (406.5 vs 294.7 psi, respectively; P = .002). Median contact area in the medial compartment was greatest for resection of both leaflets (602.7 mm(2)), but there were no statistically significant differences between test conditions (P = .70). For the lateral compartment, there were no statistically significant differences in peak pressure (P = .99) or contact area (P = .77) between test conditions. CONCLUSION Resection of a single inferior leaflet after a horizontal medial meniscal tear preserves much of the original biomechanical function of the meniscus. Resection of both leaflets leads to a significant increase in contact pressure dispersed over the same contact area, which results in an undesirable biomechanical environment. CLINICAL RELEVANCE Arthroscopic inferior leaflet resection is a viable option for providing symptomatic relief of horizontal medial meniscal tears and preserves the ability of the meniscus to absorb axial loading on the knee joint, theoretically decreasing the risk of subsequent osteoarthritis.
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Affiliation(s)
- Matthew J Brown
- Department of Orthopaedic Surgery, University at Buffalo, Buffalo, New York, USA
| | - James P Farrell
- School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, USA
| | - Melissa A Kluczynski
- Department of Orthopaedic Surgery, University at Buffalo, Buffalo, New York, USA
| | - John M Marzo
- Department of Orthopaedic Surgery, University at Buffalo, Buffalo, New York, USA
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Arno S, Bell CP, Uquillas C, Borukhov I, Walker PS. Tibiofemoral contact mechanics following a horizontal cleavage lesion in the posterior horn of the medial meniscus. J Orthop Res 2015; 33:584-90. [PMID: 25643633 DOI: 10.1002/jor.22809] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 11/19/2014] [Accepted: 12/13/2014] [Indexed: 02/04/2023]
Abstract
The purpose of this study was to determine if a horizontal cleavage lesion (HCL) of the posterior horn of the medial meniscus would result in changes to tibiofemoral contact mechanics, as measured by peak contact pressure and contact area, which can lead to cartilage degeneration. To study this, 10 cadaveric knees were tested in a rig where forces were applied (500 N Compression, 100 N shear, 2.5 Nm Torque) and the knee dynamically flexed from -5° to 135°, as peak contact pressure and contact area were recorded. After testing of the intact knee, a horizontal cleavage lesion was created arthroscopically and testing repeated. The Wilcoxon signed-rank test was used to determine if there were differences in peak contact pressure and contact area between the intact knee and that with the HCL. A statistically significant increase in peak contact pressure of 13%, on average, and a decrease in contact area of 6%, on average, was noted following the HCL. This suggests that a horizontal cleavage lesion will result in small but statistically significant changes in tibiofemoral contact mechanics which may lead to cartilage degeneration.
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Affiliation(s)
- Sally Arno
- Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, New York, New York
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Bachman DR, Thaveepunsan S, Park S, Fitzsimmons JS, An KN, O'Driscoll SW. The effect of prosthetic radial head geometry on the distribution and magnitude of radiocapitellar joint contact pressures. J Hand Surg Am 2015; 40:281-8. [PMID: 25542439 DOI: 10.1016/j.jhsa.2014.11.005] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 11/04/2014] [Accepted: 11/04/2014] [Indexed: 02/02/2023]
Abstract
PURPOSE To determine if radiocapitellar contact pressures would be elevated with nonanatomical (circular) prostheses over those mimicking native anatomy and if such pressures would be related to the depth and contour of the articular dish and to the pattern of prosthetic articulation against the lateral trochlear ridge. METHODS Three commercially available circular radial head designs were compared with an anatomical radial head and 2 modified anatomical prototype radial head designs in 10 cadaveric specimens. Each prosthesis and specimen combination was loaded in neutral rotation and maximal extension with a custom testing apparatus while measuring contact areas and pressures using thin-film pressure sensors. RESULTS Anatomical radial head prototype 2 had similar radiocapitellar contact areas and mean pressures as the native radial head; all other designs showed significant decreases in contact area and increased mean pressures. Peak contact pressures were also measured and were significantly elevated with all prostheses tested. Anatomical designs are statistically more likely to mimic normal contact with the lateral trochlear ridge and its adjacent sulcus than circular prostheses. They are also significantly less likely to have contact pressures above the 5 MPa threshold that is thought to be harmful to cartilage. The depth of the articular dish had a significant effect on contact area and pressure. CONCLUSIONS Commercially available radial head prostheses demonstrated reduced radiocapitellar contact areas and elevated contact pressures during compressive loading. These were significantly greater with symmetrical circular prostheses than with asymmetrical elliptical designs. The prosthesis that best mimicked native contact behavior was the anatomical radial head prototype 2 owing to its design for articulating with the capitellum, the lateral trochlear ridge, and the sulcus between. CLINICAL RELEVANCE Because radial head prostheses have the potential to cause capitellar erosion or arthritic change, those with lower contact pressures may lead to fewer such complications.
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Affiliation(s)
| | | | - Sangeun Park
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN
| | | | - Kai-Nan An
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN
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Chen YR, Wu YF, Tang JB, Giddins G. Contact areas of the scaphoid and lunate with the distal radius in neutral and extension: correlation of falling strategies and distal radial anatomy. J Hand Surg Eur Vol 2014; 39:379-83. [PMID: 24127465 DOI: 10.1177/1753193413507810] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The functional neutral of wrist movement is about 10° extension yet the distal radius has a volar tilt. This has not previously been explained. Assuming that the contact area between the carpus and the distal radius increased in wrist extension this would also help stabilize the carpus on the distal radius in positions where typically there is greater loading. To test this hypothesis we reconstructed three-dimensional structures of the carpal bones and distal radius using computed tomography scans of 13 normal wrists. The contact areas of the scaphoid with the distal radius were measured and were found progressively increased from flexion 20°, neutral, extension 20°, to extension 40°. The maximal increases in the contact area of the scaphoid and the distal radius was at full wrist extension. No significant changes in the contact areas of the lunate with the distal radius were found between the different positions. The contact characteristics provide greater stability to the carpus on the distal radius, and to help spread forces from impact to the wrist reducing the transmitted peak forces and thus the risk of distal radius and carpal injuries.
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Affiliation(s)
- Y R Chen
- 1Department of Hand Surgery, The Hand Surgery Research Center, Affiliated Hospital of Nantong University, Nantong, China
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Sahu D, Holmes DM, Fitzsimmons JS, Thoreson AR, Berglund LJ, An KN, O'Driscoll SW. Influence of radial head prosthetic design on radiocapitellar joint contact mechanics. J Shoulder Elbow Surg 2014; 23:456-62. [PMID: 24630544 DOI: 10.1016/j.jse.2013.11.028] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 11/14/2013] [Accepted: 11/22/2013] [Indexed: 02/01/2023]
Abstract
HYPOTHESIS Our aim was to test whether anatomically designed metallic radial head implants could better reproduce native radiocapitellar contact pressure and areas than nonanatomic implants. METHODS The distal humerus and proximal radius from 6 cadaveric upper extremities were serially tested in supination with 100 N of compression force at 4 angles of flexion (0°, 30°, 60°, and 90°). By use of a thin flexible pressure transducer, contact pressures and areas were measured for the native radial head, an anatomic implant, a nonanatomic circular monopolar implant, and a bipolar nonanatomic implant. The data (mean contact pressure and mean contact area) were modeled using a 2-factor repeated-measures analysis of variance with P ≤ .05 considered to be significant. RESULTS The mean contact areas for the prosthetic radial heads were significantly less than those seen with the intact radial heads at every angle tested (P < .01). The mean contact pressures increased significantly with all prosthetic radial head types as compared with the native head. The mean contact pressures increased by 29% with the anatomic prosthesis, 230% with the monopolar prosthesis, and 220% with the bipolar prosthesis. Peak pressures of more than 5 MPa were more commonly observed with both the monopolar and bipolar prostheses than with the anatomic or native radial heads. CONCLUSIONS The geometry of radial head implants strongly influences their contact characteristics. In a direct radius-to-capitellum axial loading experiment, an anatomically designed radial head prosthesis had lower and more evenly distributed contact pressures than the nonanatomic implants that were tested.
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Affiliation(s)
- Dipit Sahu
- Department of Orthopaedics, Biomechanics Laboratory, Mayo Clinic, Rochester, MN, USA
| | - David M Holmes
- Department of Orthopaedics, Biomechanics Laboratory, Mayo Clinic, Rochester, MN, USA
| | - James S Fitzsimmons
- Department of Orthopaedics, Biomechanics Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Andrew R Thoreson
- Department of Orthopaedics, Biomechanics Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Lawrence J Berglund
- Department of Orthopaedics, Biomechanics Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Kai-Nan An
- Department of Orthopaedics, Biomechanics Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Shawn W O'Driscoll
- Department of Orthopaedics, Biomechanics Laboratory, Mayo Clinic, Rochester, MN, USA.
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Abstract
The contact area, as well as the contact pressure, is created when a respiratory protection device (a respirator or surgical mask) contacts a human face. A computer-based algorithm for determining the contact area between a headform and N95 filtering facepiece respirator (FFR) was proposed. Six N95 FFRs were applied to five sizes of standard headforms (large, medium, small, long/narrow, and short/wide) to simulate respirator donning. After the contact simulation between a headform and an N95 FFR was conducted, a contact area was determined by extracting the intersection surfaces of the headform and the N95 FFR. Using computer-aided design tools, a superimposed contact area and an average contact area, which are non-uniform rational basis spline (NURBS) surfaces, were developed for each headform. Experiments that directly measured dimensions of the contact areas between headform prototypes and N95 FFRs were used to validate the simulation results. Headform sizes influenced all contact area dimensions (P < 0.0001), and N95 FFR sizing systems influenced all contact area dimensions (P < 0.05) except the left and right chin regions. The medium headform produced the largest contact area, while the large and small headforms produced the smallest.
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Affiliation(s)
- Zhipeng Lei
- Human-Centric Design Research Lab, Department of Mechanical Engineering, Texas Tech University, Lubbock, Texas
| | - James Yang
- Human-Centric Design Research Lab, Department of Mechanical Engineering, Texas Tech University, Lubbock, Texas
| | - Ziqing Zhuang
- National Institute for Occupational Safety and Health, Pittsburgh, Pennsylvania
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Xia D, Esser L, Tang WK, Zhou F, Zhou Y, Yu L, Yu CA. Structural analysis of cytochrome bc1 complexes: implications to the mechanism of function. Biochim Biophys Acta 2013; 1827:1278-94. [PMID: 23201476 PMCID: PMC3593749 DOI: 10.1016/j.bbabio.2012.11.008] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 11/13/2012] [Accepted: 11/19/2012] [Indexed: 01/18/2023]
Abstract
The cytochrome bc1 complex (bc1) is the mid-segment of the cellular respiratory chain of mitochondria and many aerobic prokaryotic organisms; it is also part of the photosynthetic apparatus of non-oxygenic purple bacteria. The bc1 complex catalyzes the reaction of transferring electrons from the low potential substrate ubiquinol to high potential cytochrome c. Concomitantly, bc1 translocates protons across the membrane, contributing to the proton-motive force essential for a variety of cellular activities such as ATP synthesis. Structural investigations of bc1 have been exceedingly successful, yielding atomic resolution structures of bc1 from various organisms and trapped in different reaction intermediates. These structures have confirmed and unified results of decades of experiments and have contributed to our understanding of the mechanism of bc1 functions as well as its inactivation by respiratory inhibitors. This article is part of a Special Issue entitled: Respiratory complex III and related bc complexes.
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Affiliation(s)
- Di Xia
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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McWalter EJ, O'Kane CM, Fitzpatrick DP, Wilson DR. Validation of an MRI-based method to assess patellofemoral joint contact areas in loaded knee flexion in vivo. J Magn Reson Imaging 2013; 39:978-87. [PMID: 24006182 DOI: 10.1002/jmri.24240] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 05/01/2013] [Indexed: 11/12/2022] Open
Abstract
PURPOSE To develop and validate short axial and sagittal MRI scans (<1min) to assess in vivo patellofemoral contact areas in loaded knee flexion. MATERIALS AND METHODS Contact area was assessed in four cadaver knee specimens from axial and sagittal scans using two contact area extraction techniques (delineation and intersection) and three calculation techniques (slice thickness multiplication, linear interpolation, and spline interpolation). Error was expressed as the mean absolute and percentage difference from a dye staining-based reference standard. Intrareader and intrasubject repeatability, expressed as the mean standard deviation, was determined. RESULTS Contact area assessments from the sagittal MRI scans using the delineation and slice thickness multiplication technique had the smallest error (47.7 ± 38.1 mm(2) or 10.7%). The intrareader repeatability from assessments using the sagittal scans was smaller than those using the axial scans when the delineation method was used (<9.4 ± 4.3 mm(2) and <15.4 ± 14.1 mm(2) , respectively). The intrasubject repeatability of the assessment from the sagittal scan was less than 39.9 ± 23.0 mm(2) . CONCLUSION This protocol yields assessments of contact area in less than 1 minute that have errors similar to those made using scans many times longer and can be used in series with kinematic scans to carry out simultaneous assessments in vivo to study patellofemoral joint disease.
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Affiliation(s)
- Emily J McWalter
- Department of Mechanical Engineering, University of British Columbia, Vancouver, British Columbia, Canada
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Atalay O, Kennon WR, Husain MD. Textile-based weft knitted strain sensors: effect of fabric parameters on sensor properties. Sensors (Basel) 2013; 13:11114-27. [PMID: 23966199 PMCID: PMC3812645 DOI: 10.3390/s130811114] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 08/15/2013] [Accepted: 08/16/2013] [Indexed: 12/04/2022]
Abstract
The design and development of textile-based strain sensors has been a focus of research and many investigators have studied this subject. This paper presents a new textile-based strain sensor design and shows the effect of base fabric parameters on its sensing properties. Sensing fabric could be used to measure articulations of the human body in the real environment. The strain sensing fabric was produced by using electronic flat-bed knitting technology; the base fabric was produced with elastomeric yarns in an interlock arrangement and a conductive yarn was embedded in this substrate to create a series of single loop structures. Experimental results show that there is a strong relationship between base fabric parameters and sensor properties.
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Affiliation(s)
- Ozgur Atalay
- School of Materials, University of Manchester, Manchester, M60 1QD, UK; E-Mail:
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +44-161-306-2583
| | | | - Muhammad Dawood Husain
- Department of Textile Engineering, NED University of Engineering and Technology, University Road 75270, Karachi, Pakistan
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Abstract
BACKGROUND Arthritis of the metatarsophalangeal (MTP) joint is characterized by loss of MTP joint range of motion (ROM) and pain. Joint arthroplasty is one treatment option, and while results can be satisfactory, there is still room for improvement. The aim was to use cadaveric model to compare the sagittal kinematics and articulating contact properties of 4 different first metatarsal head designs of an MTP joint implant. METHODS Six cadaveric feet were each prepared with a single modular first MTP joint total arthroplasty. A standard cyclic load, which induced hallux dorsiflexion, was applied and motion measured from high resolution images. Contact behavior was collected simultaneously using a pressure transducer. Data collected compared the native joint with 4 different reconstructed cases. Each reconstructed joint used a different metatarsal-head-component while reusing the same phalangeal component to compare the 4 alternative metatarsal head designs. RESULTS All reconstructed joints displayed greater ROM compared with the intact joint. Of the 4 metatarsal head components, the grooved, anatomical design demonstrated the greatest dorsiflexion when compared to the standard design, 31.6 degrees (SD ± 8.6 degrees), P < .05. All reconstructed joints displayed contact areas lower than the intact (~50%, P < .001). The grooved metatarsal-head-component experienced the least contact force (P < .015), and the eccentric component underwent the greatest contact pressure (P < .05) when compared to the intact case. CONCLUSIONS In this study of a first metatarsophalangeal joint replacement design, ROM was shown to be better for the more anatomically designed metatarsal head, while contact properties did not vary across different designs. CLINICAL RELEVANCE This information may be useful in the development of new metatarsal components.
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Affiliation(s)
- Tim Schneider
- Murray Maxwell Biomechanics Laboratory, Kolling Institute, University of Sydney, Royal North Shore Hospital, Sydney, Australia
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