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Bi T, Eggers BT, Cohen RE, Campbell BJ, Strobel T. Computational Screening and Stabilization of Boron-Substituted Type-I and Type-II Carbon Clathrates. J Am Chem Soc 2024; 146:7985-7997. [PMID: 38051138 DOI: 10.1021/jacs.3c08362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
Boron substitution represents a promising approach to stabilize carbon clathrate structures, but no thermodynamically stable substitution schemes have been identified for frameworks other than the type-VII (sodalite) structure type. To investigate the possibility for additional tetrahedral carbon-based clathrate networks, more than 5000 unique boron decoration schemes were investigated computationally for type-I and type-II carbon clathrates with a range of guest elements including Li, Na, K, Rb, Cs, Mg, Ca, Sr, and Ba. Density functional theory calculations were performed at 10 and 50 GPa, and the stability and impact of boron substitution were evaluated. The results indicate that the boron-substituted carbon clathrates are stabilized under high-pressure conditions. Full cage occupancies of intermediate-sized guest atoms (e.g., Na, Ca, and Sr) are the most favorable energetically. Clathrate stability is maximized when the boron atoms are substituted within the hexagonal rings of the large [51262]/[51264] cages. Several structures with favorable formation enthalpies <-200 meV/atom were predicted, and type-I Ca8B16C30 is on the convex hull at 50 GPa. This structure represents the first thermodynamically stable type-I clathrate identified and suggests that boron-substituted carbon clathrates may represent a large family of diamond-like framework materials with a range of structure types and guest/framework substitutions.
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Affiliation(s)
- Tiange Bi
- Earth and Planets Laboratory, Carnegie Institution for Science, 5241 Broad Branch Road, Northwest, Washington, D.C., Washington 20015, United States
| | - Bryce T Eggers
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, United States
| | - R E Cohen
- Earth and Planets Laboratory, Carnegie Institution for Science, 5241 Broad Branch Road, Northwest, Washington, D.C., Washington 20015, United States
| | - Branton J Campbell
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, United States
| | - Timothy Strobel
- Earth and Planets Laboratory, Carnegie Institution for Science, 5241 Broad Branch Road, Northwest, Washington, D.C., Washington 20015, United States
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Yakoub G, Choi YS, Wong RP, Strauch T, Ann KJ, Cohen RE, Ulrich HD. Avidity-based biosensors for ubiquitylated PCNA reveal choreography of DNA damage bypass. Sci Adv 2023; 9:eadf3041. [PMID: 37672592 PMCID: PMC10482348 DOI: 10.1126/sciadv.adf3041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 08/03/2023] [Indexed: 09/08/2023]
Abstract
In eukaryotes, the posttranslational modifier ubiquitin is used to regulate the amounts, interactions, or activities of proteins in diverse pathways and signaling networks. Its effects are mediated by monoubiquitin or polyubiquitin chains of varying geometries. We describe the design, validation, and application of a series of avidity-based probes against the ubiquitylated forms of the DNA replication clamp, proliferating cell nuclear antigen (PCNA), in budding yeast. Directed against total ubiquitylated PCNA or specifically K63-polyubiquitylated PCNA, the probes are tunable in their activities and can be used either as biosensors or as inhibitors of the PCNA-dependent DNA damage bypass pathway. Used in live cells, the probes revealed the timing of PCNA ubiquitylation during damage bypass and a particular susceptibility of the ribosomal DNA locus to the activation of the pathway. Our approach is applicable to a wide range of ubiquitin-conjugated proteins, thus representing a generalizable strategy for the design of biosensors for specific (poly)ubiquitylated forms of individual substrates.
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Affiliation(s)
- George Yakoub
- Institute of Molecular Biology gGmbH, Ackermannweg 4, D-55128 Mainz, Germany
| | - Yun-Seok Choi
- Department of Biochemistry and Molecular Biology, Colorado State University, 273 MRB, 1870 Campus Delivery, Fort Collins, CO 80523-1870, USA
| | - Ronald P. Wong
- Institute of Molecular Biology gGmbH, Ackermannweg 4, D-55128 Mainz, Germany
| | - Tina Strauch
- Institute of Molecular Biology gGmbH, Ackermannweg 4, D-55128 Mainz, Germany
| | - Kezia J. Ann
- Institute of Molecular Biology gGmbH, Ackermannweg 4, D-55128 Mainz, Germany
| | - Robert E. Cohen
- Department of Biochemistry and Molecular Biology, Colorado State University, 273 MRB, 1870 Campus Delivery, Fort Collins, CO 80523-1870, USA
| | - Helle D. Ulrich
- Institute of Molecular Biology gGmbH, Ackermannweg 4, D-55128 Mainz, Germany
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3
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Zou MY, Cohen RE, Ursomanno BL, Yerke LM. Use of Systemic Steroids, Hormone Replacement Therapy, or Oral Contraceptives Is Associated with Decreased Implant Survival in Women. Dent J (Basel) 2023; 11:163. [PMID: 37504229 PMCID: PMC10377784 DOI: 10.3390/dj11070163] [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: 03/22/2023] [Revised: 06/07/2023] [Accepted: 06/27/2023] [Indexed: 07/29/2023] Open
Abstract
BACKGROUND Systemic steroids, such as prednisone, hormonal replacement therapies, or oral contraceptives, are commonly prescribed to women who might also be receiving dental implant therapy. However, the effect of these medications on dental implant survival is unknown. METHODS The medical and dental records of individuals with dental implants (N = 1480 implants) who visited a postgraduate periodontics clinic between 2000 and 2017 were initially considered. Those younger than 21 years old, pregnant, or male were excluded according to the study's exclusion criteria. The presence of systemic diseases and conditions was assessed. Implant failure rates among female patients using systemic steroids, hormone replacement therapy, or oral contraceptives were compared with failure rates among patients not taking those medications. RESULTS The implant failure rate for the 65 implants in patients taking steroid medications was 7.69%; the failure rate for the 712 implants in patients not taking steroids was 1.54% (p < 0.001). After adjusting for smoking and the presence of diabetes, that relationship persisted, with an 8.47% implant failure rate for the 59 implants in patients taking steroids (vs. 1.54% failure for the 585 implants in patients not taking steroids; p < 0.001). Regression analyses demonstrated that the odds of implant failure versus success were 5.31 times greater in patients taking systemic steroids, hormone replacement therapy, or oral contraceptives (p < 0.05). No statistically significant differences in patient plaque control were found between the experimental and control groups. CONCLUSIONS Among women, the use of systemic steroids is associated with a five-fold increase in the rate of dental implant failure, regardless of the presence of smoking or diabetes.
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Affiliation(s)
- Michelle Y Zou
- Department of Periodontics and Endodontics, School of Dental Medicine, University at Buffalo, The State University of New York, Buffalo, NY 14214, USA
| | - Robert E Cohen
- Department of Periodontics and Endodontics, School of Dental Medicine, University at Buffalo, The State University of New York, Buffalo, NY 14214, USA
| | - Brendon L Ursomanno
- Department of Periodontics and Endodontics, School of Dental Medicine, University at Buffalo, The State University of New York, Buffalo, NY 14214, USA
| | - Lisa M Yerke
- Department of Periodontics and Endodontics, School of Dental Medicine, University at Buffalo, The State University of New York, Buffalo, NY 14214, USA
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Choi YS, Cohen RE. Real-Time Deubiquitination Assays Using a Free Ubiquitin Sensor. Methods Mol Biol 2023; 2591:255-267. [PMID: 36350553 DOI: 10.1007/978-1-0716-2803-4_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Deubiquitinating enzymes cleave ubiquitin (Ub) from its attachment to another Ub, other proteins, peptides, or non-peptide adducts. In all cases, substrate hydrolysis by DUBs releases free Ub or polyubiquitin (polyUb) chains. Whereas most quantitative DUB assays depend on fluorescently labeled artificial substrates, employing a sensor able to detect Ub release in real time makes it possible to monitor DUB activity using virtually any Ub conjugate as a substrate. The protocols here describe the preparation of Atto532-tUI, a high-affinity sensor for free Ub, and its use in real-time deubiquitination assays.
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Affiliation(s)
- Yun-Seok Choi
- School of Natural Sciences, Black Hills State University, Spearfish, SD, USA
| | - Robert E Cohen
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA.
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5
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Chawla BK, Cohen RE, Stellrecht EM, Yerke LM. The influence of proton pump inhibitors on tissue attachment around teeth and dental implants: A scoping review. Clin Exp Dent Res 2022; 8:1045-1058. [PMID: 35799099 PMCID: PMC9562794 DOI: 10.1002/cre2.616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 06/03/2022] [Accepted: 06/10/2022] [Indexed: 11/11/2022] Open
Abstract
Objectives Materials and Methods Results Conclusions
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Affiliation(s)
- Bhavneet K. Chawla
- Department of Periodontics and Endodontics, School of Dental Medicine, University at Buffalo The State University of New York Buffalo New York USA
| | - Robert E. Cohen
- Department of Periodontics and Endodontics, School of Dental Medicine, University at Buffalo The State University of New York Buffalo New York USA
| | - Elizabeth M. Stellrecht
- University Libraries, University at Buffalo The State University of New York Buffalo New York USA
| | - Lisa M. Yerke
- Department of Periodontics and Endodontics, School of Dental Medicine, University at Buffalo The State University of New York Buffalo New York USA
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Aldulaijan HA, Alsharif SB, Cohen RE, Yerke LM. Familial Presentation of Ankyloglossia and Localized Periodontitis. Compend Contin Educ Dent 2022; 43:288-291. [PMID: 35589147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
An association between ankyloglossia and periodontitis has not previously been reported. This case series describes three sisters who each had ankyloglossia and a molar/incisor pattern of localized periodontitis. The concurrent presentation of both conditions within the family suggests that further investigation of genetic factors that might concurrently affect the pathogenesis of both disorders may be warranted.
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Affiliation(s)
- Hajer A Aldulaijan
- Assistant Professor, King Saud University, College of Dentistry, Department of Periodontics and Community Dentistry, Riyadh, Saudi Arabia
| | - Shahad B Alsharif
- Assistant Professor, King Abdulaziz University, Faculty of Dentistry, Department of Periodontology, Jeddah, Saudi Arabia
| | - Robert E Cohen
- Professor, University at Buffalo, The State University of New York, School of Dental Medicine, Department of Periodontics and Endodontics, Buffalo, New York
| | - Lisa M Yerke
- Clinical Associate Professor, and Director, Advanced Education Program in Periodontics, University at Buffalo, The State University of New York, School of Dental Medicine, Department of Periodontics and Endodontics, Buffalo, New York
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Passos CDS, Cohen RE, Yao T. Laser Microirradiation and Real-time Recruitment Assays Using an Engineered Biosensor. Bio Protoc 2022; 12:e4337. [PMID: 35592609 PMCID: PMC8918221 DOI: 10.21769/bioprotoc.4337] [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: 01/06/2022] [Revised: 11/05/2021] [Accepted: 01/18/2022] [Indexed: 12/29/2022] Open
Abstract
Double-strand breaks (DSBs) are lesions in DNA that, if not properly repaired, can cause genomic instability, oncogenesis, and cell death. Multiple chromatin posttranslational modifications (PTMs) play a role in the DNA damage response to DSBs. Among these, RNF168-mediated ubiquitination of lysines 13 or 15 at the N-terminal tail of histone H2A (H2AK13/15Ub) is essential for the recruitment of effectors of both the non-homologous end joining (NHEJ) and the homologous recombination (HR) repair pathways. Thus, tools and techniques to track the spatiotemporal dynamics of H2AK13/15 ubiquitination at DNA DSBs are important to facilitate studies of DNA repair. Previous work from other groups used the minimal focus-forming region (FFR) of the NHEJ effector 53BP1 to detect H2AK15Ub generated upon damage induced by gamma or laser irradiation in live cells. However, 53BP1-FFR only binds nucleosomes modified with both H2AK15Ub and dimethylation of lysine 20 on histone H4 (H4K20me2); thus, 53BP1-FFR does not recognize H2AK13Ub-nucleosomes or nucleosomes that contain H2AK15Ub but lack methylation of H4K20 (H4K20me0). To overcome this limitation, we developed an avidity-based sensor that binds H2AK13/15Ub without dependence on the methylation status of histone H4K20. This sensor, called Reader1.0, detects DNA damage-associated H2AK13/15Ub in live cells with high sensitivity and selectivity. Here, we present a protocol to detect the formation of H2AK13/15Ub at laser-induced DSBs using Reader1.0 as a live-cell reporter for this histone PTM. Graphic abstract.
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Affiliation(s)
| | - Robert E. Cohen
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA,
*For correspondence: ;
| | - Tingting Yao
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA,
*For correspondence: ;
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Kraus RG, Hemley RJ, Ali SJ, Belof JL, Benedict LX, Bernier J, Braun D, Cohen RE, Collins GW, Coppari F, Desjarlais MP, Fratanduono D, Hamel S, Krygier A, Lazicki A, Mcnaney J, Millot M, Myint PC, Newman MG, Rygg JR, Sterbentz DM, Stewart ST, Stixrude L, Swift DC, Wehrenberg C, Eggert JH. Measuring the melting curve of iron at super-Earth core conditions. Science 2022; 375:202-205. [PMID: 35025665 DOI: 10.1126/science.abm1472] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The discovery of more than 4500 extrasolar planets has created a need for modeling their interior structure and dynamics. Given the prominence of iron in planetary interiors, we require accurate and precise physical properties at extreme pressure and temperature. A first-order property of iron is its melting point, which is still debated for the conditions of Earth’s interior. We used high-energy lasers at the National Ignition Facility and in situ x-ray diffraction to determine the melting point of iron up to 1000 gigapascals, three times the pressure of Earth’s inner core. We used this melting curve to determine the length of dynamo action during core solidification to the hexagonal close-packed (hcp) structure. We find that terrestrial exoplanets with four to six times Earth’s mass have the longest dynamos, which provide important shielding against cosmic radiation.
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Affiliation(s)
- Richard G Kraus
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Russell J Hemley
- Departments of Physics, Chemistry, and Earth and Environmental Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Suzanne J Ali
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Jonathan L Belof
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Lorin X Benedict
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Joel Bernier
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Dave Braun
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - R E Cohen
- Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC 20015, USA
| | - Gilbert W Collins
- Department of Mechanical Engineering, Department of Physics and Astronomy, and Laboratory for Laser Energetics, University of Rochester, Rochester, NY 14627, USA
| | - Federica Coppari
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | | | | | - Sebastien Hamel
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Andy Krygier
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Amy Lazicki
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - James Mcnaney
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Marius Millot
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Philip C Myint
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Matthew G Newman
- Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125, USA
| | - James R Rygg
- Department of Mechanical Engineering, Department of Physics and Astronomy, and Laboratory for Laser Energetics, University of Rochester, Rochester, NY 14627, USA
| | - Dane M Sterbentz
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Sarah T Stewart
- Department of Earth and Planetary Sciences, University of California Davis, Davis, CA 95616, USA
| | - Lars Stixrude
- Department of Earth, Planetary, and Space Sciences, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Damian C Swift
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Chris Wehrenberg
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Jon H Eggert
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
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Song A, Hazlett Z, Abeykoon D, Dortch J, Dillon A, Curtiss J, Martinez SB, Hill CP, Yu C, Huang L, Fushman D, Cohen RE, Yao T. Branched ubiquitin chain binding and deubiquitination by UCH37 facilitate proteasome clearance of stress-induced inclusions. eLife 2021; 10:72798. [PMID: 34761751 PMCID: PMC8635973 DOI: 10.7554/elife.72798] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [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: 08/04/2021] [Accepted: 11/10/2021] [Indexed: 12/20/2022] Open
Abstract
UCH37, also known as UCHL5, is a highly conserved deubiquitinating enzyme (DUB) that associates with the 26S proteasome. Recently, it was reported that UCH37 activity is stimulated by branched ubiquitin (Ub) chain architectures. To understand how UCH37 achieves its unique debranching specificity, we performed biochemical and Nuclear Magnetic Resonance (NMR) structural analyses and found that UCH37 is activated by contacts with the hydrophobic patches of both distal Ubs that emanate from a branched Ub. In addition, RPN13, which recruits UCH37 to the proteasome, further enhances branched-chain specificity by restricting linear Ub chains from having access to the UCH37 active site. In cultured human cells under conditions of proteolytic stress, we show that substrate clearance by the proteasome is promoted by both binding and deubiquitination of branched polyubiquitin by UCH37. Proteasomes containing UCH37(C88A), which is catalytically inactive, aberrantly retain polyubiquitinated species as well as the RAD23B substrate shuttle factor, suggesting a defect in recycling of the proteasome for the next round of substrate processing. These findings provide a foundation to understand how proteasome degradation of substrates modified by a unique Ub chain architecture is aided by a DUB.
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Affiliation(s)
- Aixin Song
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
| | - Zachary Hazlett
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
| | - Dulith Abeykoon
- Department of Chemistry and Biochemistry, University of Maryland, College Park, United States
| | - Jeremy Dortch
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
| | - Andrew Dillon
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
| | - Justin Curtiss
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
| | - Sarah Bollinger Martinez
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
| | - Christopher P Hill
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - Clinton Yu
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, United States
| | - Lan Huang
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, United States
| | - David Fushman
- Department of Chemistry and Biochemistry, University of Maryland, College Park, United States
| | - Robert E Cohen
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
| | - Tingting Yao
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
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10
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Chawla BK, Cohen RE, Yerke LM. Association between proton pump inhibitors and periodontal disease severity. Clin Exp Dent Res 2021; 8:395-401. [PMID: 34545705 PMCID: PMC8874058 DOI: 10.1002/cre2.495] [Citation(s) in RCA: 3] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 09/02/2021] [Accepted: 09/05/2021] [Indexed: 01/07/2023] Open
Abstract
Objectives Proton pump inhibitors (PPIs) are commonly prescribed for the management of acid‐related gastrointestinal disorders. PPIs modulate osteoclast function, reduce gastric acid secretion, and are associated with the establishment of a more diverse gastrointestinal microbiota. Periodontitis is characterized by microbe‐associated host‐mediated inflammation that results in loss of periodontal attachment. The aim of this study was to assess whether a relationship exists between PPIs and periodontal disease. Materials and methods A retrospective analysis was performed using patient records from a faculty periodontal practice. The proportion of elevated probing depths was used to measure periodontitis severity. Statistical analysis was performed using independent sample t‐tests, and Chi‐square tests of independence. Results Records from 1093 patients were initially assessed. Fourteen percent of teeth were associated with ≥6 mm probing depths among PPI users, in contrast to 24% for patients not using PPIs (P = 0.030). Similarly, 27% of teeth exhibited ≥5 mm probing depths among PPI users versus 40% for non‐PPI users (P = 0.039). Conclusions The results suggest that PPIs are associated with a reduced proportion of elevated probing depths. Future prospective studies are indicated to elucidate possible mechanisms through which PPIs might affect, and potentially be used in the treatment of, periodontitis.
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Affiliation(s)
- Bhavneet K Chawla
- Department of Periodontics and Endodontics, School of Dental Medicine, The State University of New York, University at Buffalo, Buffalo, New York, USA
| | - Robert E Cohen
- Department of Periodontics and Endodontics, School of Dental Medicine, The State University of New York, University at Buffalo, Buffalo, New York, USA
| | - Lisa M Yerke
- Department of Periodontics and Endodontics, School of Dental Medicine, The State University of New York, University at Buffalo, Buffalo, New York, USA
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Dos Santos Passos C, Choi YS, Snow CD, Yao T, Cohen RE. Design of genetically encoded sensors to detect nucleosome ubiquitination in live cells. J Cell Biol 2021; 220:211785. [PMID: 33570569 PMCID: PMC7883740 DOI: 10.1083/jcb.201911130] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 12/22/2020] [Accepted: 01/04/2021] [Indexed: 02/07/2023] Open
Abstract
Histone posttranslational modifications (PTMs) are dynamic, context-dependent signals that modulate chromatin structure and function. Ubiquitin (Ub) conjugation to different lysines of histones H2A and H2B is used to regulate diverse processes such as gene silencing, transcriptional elongation, and DNA repair. Despite considerable progress made to elucidate the players and mechanisms involved in histone ubiquitination, there remains a lack of tools to monitor these PTMs, especially in live cells. To address this, we combined an avidity-based strategy with in silico approaches to design sensors for specifically ubiquitinated nucleosomes. By linking Ub-binding domains to nucleosome-binding peptides, we engineered proteins that target H2AK13/15Ub and H2BK120Ub with Kd values from 10−8 to 10−6 M; when fused to fluorescent proteins, they work as PTM sensors in cells. The H2AK13/15Ub-specific sensor, employed to monitor signaling from endogenous DNA damage through the cell cycle, identified and differentiated roles for 53BP1 and BARD1 as mediators of this histone PTM.
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Affiliation(s)
| | - Yun-Seok Choi
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO
| | - Christopher D Snow
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO.,Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, CO
| | - Tingting Yao
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO
| | - Robert E Cohen
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO
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Zhu L, Strobel TA, Cohen RE. Prediction of an Extended Ferroelectric Clathrate. Phys Rev Lett 2020; 125:127601. [PMID: 33016718 DOI: 10.1103/physrevlett.125.127601] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 07/08/2020] [Accepted: 08/14/2020] [Indexed: 06/11/2023]
Abstract
Using first-principles calculations, we predict a lightweight room-temperature ferroelectric carbon-boron framework in a host-guest clathrate structure. This ferroelectric clathrate, with composition ScB_{3}C_{3}, exhibits high polarization density and low mass density compared with widely used commercial ferroelectrics. Molecular dynamics simulations show spontaneous polarization with a moderate above-room-temperature T_{c} of ∼370 K, which implies large susceptibility and possibly large electrocaloric and piezoelectric constants at room temperature. Our findings open the possibility for a new class of ferroelectric materials with potential across a broad range of applications.
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Affiliation(s)
- Li Zhu
- Extreme Materials Initiative, Earth and Planets Laboratory, Carnegie Institution for Science, 5251 Broad Branch Road NW, Washington, D.C. 20015, USA
| | - Timothy A Strobel
- Extreme Materials Initiative, Earth and Planets Laboratory, Carnegie Institution for Science, 5251 Broad Branch Road NW, Washington, D.C. 20015, USA
| | - R E Cohen
- Extreme Materials Initiative, Earth and Planets Laboratory, Carnegie Institution for Science, 5251 Broad Branch Road NW, Washington, D.C. 20015, USA
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Zhang Y, Hou M, Liu G, Zhang C, Prakapenka VB, Greenberg E, Fei Y, Cohen RE, Lin JF. Reconciliation of Experiments and Theory on Transport Properties of Iron and the Geodynamo. Phys Rev Lett 2020; 125:078501. [PMID: 32857557 DOI: 10.1103/physrevlett.125.078501] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 07/13/2020] [Indexed: 06/11/2023]
Abstract
We measure the electrical resistivity of hcp iron up to ∼170 GPa and ∼3000 K using a four-probe van der Pauw method coupled with homogeneous flattop laser heating in a DAC, and compute its electrical and thermal conductivity by first-principles molecular dynamics including electron-phonon and electron-electron scattering. We find that the measured resistivity of hcp iron increases almost linearly with temperature, and is consistent with our computations. The results constrain the resistivity and thermal conductivity of hcp iron to ∼80±5 μΩ cm and ∼100±10 W m^{-1} K^{-1}, respectively, at conditions near the core-mantle boundary. Our results indicate an adiabatic heat flow of ∼10±1 TW out of the core, supporting a present-day geodynamo driven by thermal and compositional convection.
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Affiliation(s)
- Youjun Zhang
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201900, China
| | - Mingqiang Hou
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201900, China
- The Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Guangtao Liu
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201900, China
| | - Chengwei Zhang
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201900, China
| | - Vitali B Prakapenka
- Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637, USA
| | - Eran Greenberg
- Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637, USA
| | - Yingwei Fei
- Extreme Materials Initiative, Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC 20015-1305, USA
| | - R E Cohen
- Extreme Materials Initiative, Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC 20015-1305, USA
| | - Jung-Fu Lin
- Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas 78712, USA
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14
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Abstract
Hypothyroidism (HT) is an endocrine disorder characterized by abnormally reduced thyroid gland activity and is most commonly of autoimmune etiology. HT is associated with alterations in bone metabolism, and HT patients typically experience decreased bone resorption. The objective of this study was to use dental implants as standardized reference markers to compare the extent of alveolar bone loss in implant patients with and without HT. We examined medical and dental history records and radiographic data from 635 patients receiving 1480 implants during 2000–2017. The rate of bone loss was calculated from differences in radiographic bone levels over time, corrected for radiographic distortion. Peri-implant bone loss from patients with HT was significantly lower than for those without HT (t1252= −3.42; 95% confidence interval= 0.47–1.73; P < .001; M = 0.53 and 1.63 mm/yr, respectively). A similar relationship persisted after excluding smokers and diabetics and after additionally excluding those on systemic steroids, hormone replacement therapy, hormone medications, or autoimmune diseases other than HT. Our data suggest that patients with HT have a decreased rate of bone loss around dental implants and may not be at increased risk for dental implant failure. The decreased bone metabolic rate among patients with HT might contribute to those findings.
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Affiliation(s)
- Brendon L. Ursomanno
- Department of Periodontics and Endodontics School of Dental Medicine, University at Buffalo, The State University of New York, Buffalo, NY
| | - Robert E. Cohen
- Department of Periodontics and Endodontics School of Dental Medicine, University at Buffalo, The State University of New York, Buffalo, NY
| | - Michael J. Levine
- Department of Periodontics and Endodontics School of Dental Medicine, University at Buffalo, The State University of New York, Buffalo, NY
| | - Lisa M. Yerke
- Department of Periodontics and Endodontics School of Dental Medicine, University at Buffalo, The State University of New York, Buffalo, NY
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15
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Girard HL, Bourrianne P, Yeganeh M, Cohen RE, McKinley GH, Varanasi KK. Lubricant-Impregnated Surfaces for Mitigating Asphaltene Deposition. ACS Appl Mater Interfaces 2020; 12:28750-28758. [PMID: 32515182 DOI: 10.1021/acsami.0c03967] [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] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Asphaltenes are heavy aromatic components of crude oil. Their complex chemical makeup-an aromatic core surrounded by aliphatic side chains-enables them to adhere to most surfaces. Their buildup in pipes can result in clogging and lead to interruption of production operations and expensive mechanical cleaning. We demonstrate the use of liquid-impregnated surfaces (LIS) to prevent asphaltene deposition and buildup on substrates. Indeed, these surfaces expose a liquid interface to the working fluid, which combines the benefits of a dynamic defect-free surface and tunable interfacial properties. In contrast to bulk additives that are typically mixed into the oil phase, the impregnating liquid also provides the great benefit of protecting the underlying solid surface with a stable and minimal layer of lubricant, thereby reducing costs and eliminating the need for subsequent downstream removal. We first select and confirm the thermodynamic stability of a suitable lubricant and its lack of interaction with asphaltenes. By using a carefully selected system composed of a textured and functionalized solid substrate in conjunction with a fluorinated lubricant, we show that asphaltene adsorption is prevented over long time scales. We further demonstrate the possibility of building such a system with representative industrial materials such as aluminum and expose the resulting substrate to an external shear flow to simulate pipe flow conditions.
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Affiliation(s)
- Henri-Louis Girard
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02119, United States
| | - Philippe Bourrianne
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02119, United States
| | - Mohsen Yeganeh
- ExxonMobil Research and Engineering Company, Annandale, New Jersey 08801, United States
| | - Robert E Cohen
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02119, United States
| | - Gareth H McKinley
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02119, United States
| | - Kripa K Varanasi
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02119, United States
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16
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Taketa TB, Rocha Neto JBM, Dos Santos DM, Fiamingo A, Beppu MM, Campana-Filho SP, Cohen RE, Rubner MF. Tracking Sulfonated Polystyrene Diffusion in a Chitosan/Carboxymethyl Cellulose Layer-by-Layer Film: Exploring the Internal Architecture of Nanocoatings. Langmuir 2020; 36:4985-4994. [PMID: 32316733 DOI: 10.1021/acs.langmuir.0c00544] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Since chitosan presents the ability to interact with a wide range of molecules, it has been one of the most popular natural polymers for the construction of layer-by-layer thin films. In this study, depth-profiling X-ray photoelectron spectroscopy (XPS) was employed to track the diffusion of sulfonated polystyrene (SPS) in carboxymethyl cellulose/chitosan (CMC/Chi) multilayers. Our findings suggest that the CMC/Chi film does not constitute an electrostatic barrier sufficient to block diffusion of SPS, and that diffusion can be controlled by adjusting the diffusion time and the molecular weight of the polymers that compose the CMC/Chi system. In addition to monitoring the diffusion, it was also possible to observe a process of preferential interaction between Chi and SPS. Thus, the nitrogen N 1s peak, due to functional groups found exclusively in chitosan chains, was the key factor to identifying the molecular interactions involving chitosan and the different polyanions. Accordingly, the presence of a strong polyanion such as SPS shifts the N 1s peak to a higher level of binding energy. Such results highlight that understanding the fundamentals of polymer interactions is a major step to fine-tuning the internal architecture of LbL structures for specific applications (e.g., drug release).
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Affiliation(s)
- Thiago B Taketa
- School of Chemical Engineering, University of Campinas, Campinas, São Paulo 13083-970, Brazil
| | | | - Danilo M Dos Santos
- Institute of Chemistry of São Carlos, University of São Paulo, São Carlos, São Paulo 13566-590, Brazil
| | - Anderson Fiamingo
- Institute of Chemistry of São Carlos, University of São Paulo, São Carlos, São Paulo 13566-590, Brazil
| | - Marisa M Beppu
- School of Chemical Engineering, University of Campinas, Campinas, São Paulo 13083-970, Brazil
| | | | - Robert E Cohen
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Michael F Rubner
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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17
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Yerke LM, Cohen RE. MON-397 Potential Relationship Between Hypothyroidism and Bone Loss at Dental Implants. J Endocr Soc 2020. [PMCID: PMC7207468 DOI: 10.1210/jendso/bvaa046.040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Introduction: Hypothyroidism (HT) is an endocrine condition with autoimmune and inflammatory etiologies. Studies have shown that both periodontal disease and peri-implant bone loss are bidirectionally influenced by systemic inflammatory conditions, such as diabetes, adverse pregnancy outcomes, cardiovascular disease, and osteoporosis.1 There also is evidence that HT is associated with decreased bone metabolism, depressed bone turnover, and a prolonged bone remodeling cycle.2 Consequently, the objective of this study was to determine if the severity of bone loss around dental implants is related to the presence of HT. Methods: Following IRB approval, medical, dental, and radiographic records of patients who received dental implant placement at a university-based postgraduate program in periodontics from 2000–2017 were reviewed (1480 implants; 635 patients). Rate of bone loss in mm/year was calculated from surgical implant placement and subsequent re-evaluation radiographs, with correction for radiographic distortion. Presence of HT was confirmed by review of patient medical records, clinical diagnosis of HT, and history of thyroid hormone supplementation. Populations were adjusted for smoking, diabetes, use of systemic steroids, presence of autoimmune disease (other than HT), and systemic inflammatory conditions. Calculations were performed using IBM SPSS Statistics v25. Results: Patients with HT had a decreased rate of crestal alveolar bone loss around dental implants. Specifically, patients with HT experienced peri-implant bone loss at a rate of 0.42 mm/year, while bone loss from patients without HT was 1.34 mm/year (68.7% decrease; mean difference = 0.92 mm/year, 95% confidence interval = 0.39–1.50 mm/year, P<0.002). There were no significant differences in patient oral hygiene, or in implant service time, among any of the groups studied (P>0.05). Conclusions: The results suggest that the rate of marginal alveolar bone loss at dental implants is significantly decreased in patients with HT, and occurs independently of any of the systemic conditions noted above. The findings imply that potential changes in bone metabolism and remodeling associated with HT might result in less peri-implant alveolar bone loss following implant placement surgery. As a result, there does not appear to be an increased risk of peri-implant crestal bone loss in patients with HT. References: 1Kim J., Amar S., Odontol. 94(1):10–21, 2006. 2Tuchendler D., and Bolanowski M.,Thyroid Res. 7:12, 2014.
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Affiliation(s)
- Lisa Marie Yerke
- School of Dental Medicine, University at Buffalo, Buffalo, NY, USA
| | - Robert E Cohen
- University at Buffalo, State University of New York, Buffalo, NY, USA
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18
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Girard HL, Bourrianne P, Chen D, Jaishankar A, Vreeland JL, Cohen RE, Varanasi KK, McKinley GH. Asphaltene Adsorption on Functionalized Solids. Langmuir 2020; 36:3894-3902. [PMID: 32090578 PMCID: PMC7307966 DOI: 10.1021/acs.langmuir.0c00029] [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] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Indexed: 06/10/2023]
Abstract
Asphaltenes, heavy aromatic components of crude oil, are known to adsorb on surfaces and can lead to pipe clogging or hinder oil recovery. Because of their multicomponent structure, the details of their interactions with surfaces are complex. We investigate the effect of the physicochemical properties of the substrate on the extent and mechanism of this adsorption. Using wetting measurements, we relate the initial kinetics of deposition to the interfacial energy of the surface. We then quantify the long-term adsorption dynamics using a quartz crystal microbalance and ellipsometry. Finally, we investigate the mechanism and morphology of adsorption with force spectroscopy measurements as a function of surface chemistry. We determine different adsorption regimes differing in orientation, packing density, and initial kinetics on different substrate functionalizations. Specifically, we find that alkane substrates delay the initial monolayer formation, fluorinated surfaces exhibit fast adsorption but low bonding strength, and hydroxyl substrates lead to a different adsorption orientation and a high packing density of the asphaltene layer.
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Affiliation(s)
- Henri-Louis Girard
- Department
of Mechanical Engineering, MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Philippe Bourrianne
- Department
of Mechanical Engineering, MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Dayong Chen
- Department
of Chemical Engineering, MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Aditya Jaishankar
- ExxonMobil
Research and Engineering Company, Annandale, New Jersey 08801, United States
| | - Jessica L. Vreeland
- ExxonMobil
Research and Engineering Company, Annandale, New Jersey 08801, United States
| | - Robert E. Cohen
- Department
of Chemical Engineering, MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Kripa K. Varanasi
- Department
of Mechanical Engineering, MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Gareth H. McKinley
- Department
of Mechanical Engineering, MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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19
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Aldulaijan HA, Cohen RE, Stellrecht EM, Levine MJ, Yerke LM. Relationship between hypothyroidism and periodontitis: A scoping review. Clin Exp Dent Res 2020; 6:147-157. [PMID: 32067402 PMCID: PMC7025985 DOI: 10.1002/cre2.247] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 08/20/2019] [Accepted: 08/25/2019] [Indexed: 12/11/2022] Open
Abstract
AIM The objective of this study was to assess the existing literature to determine if a relationship exists between hypothyroidism and periodontitis. METHODS We used a modified approach to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses by searching five databases in addition to the gray literature. Keywords in the title and abstract fields, as well as subject headings for both periodontal disease and hypothyroidism, were used to search the existing literature for publications relevant to evaluation of the thyroid-periodontitis relationship. RESULTS The authors screened 847 unique publications which, after applying inclusion and exclusion criteria, yielded 29 publications, which were further analyzed for relevance and applicability. Most of the included papers were cross-sectional studies and retrospective chart reviews. Following critical analysis, four publications, including one abstract, were used to further assess the hypothyroid-periodontitis relationship. CONCLUSIONS There are very few high-quality studies describing the potential association between hypothyroidism and periodontitis. In general, and among the included papers with the fewest confounding factors, a positive relationship between hypothyroidism and periodontitis was found. Further well-controlled, prospective clinical and immunologic studies will be required to confirm that relationship.
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Affiliation(s)
- Hajer A. Aldulaijan
- Department of Periodontics and EndodonticsUniversity at Buffalo, State University of New York, School of Dental MedicineBuffaloNew York
- Present address:
Department of Periodontics and Community DentistryKing Saud University, College of DentistryRiyadhSaudi Arabia
| | - Robert E. Cohen
- Department of Periodontics and EndodonticsUniversity at Buffalo, State University of New York, School of Dental MedicineBuffaloNew York
| | - Elizabeth M. Stellrecht
- Department of Periodontics and EndodonticsUniversity at Buffalo, State University of New York, School of Dental MedicineBuffaloNew York
| | - Michael J. Levine
- Department of Periodontics and EndodonticsUniversity at Buffalo, State University of New York, School of Dental MedicineBuffaloNew York
| | - Lisa M. Yerke
- Department of Periodontics and EndodonticsUniversity at Buffalo, State University of New York, School of Dental MedicineBuffaloNew York
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20
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Abstract
In all eukaryotic cells, modifications of proteins by polymers of ubiquitin (polyUb) are signals used in diverse biological processes. To better understand how polyUb signals are read and promote their different functions, quantitative measurements of their interactions with receptor proteins are needed. However, affinities and selectivities of different forms of polyUb with various receptors have been difficult to determine because the availability of well-defined polyUb chains can be limiting and there is a lack of general, sensitive methods to assay their interactions. We have addressed this challenge by developing a series of fluorescent protein sensors for polyUb; by competition of the sensors against receptor proteins in vitro for limiting amounts of polyUb, receptor·polyUb affinities can be quantified. Due to the high affinities of the polyUb sensors (Kd ∼ 10-9 M), binding assays using this competition format require much less polyUb (<0.1%) than would be needed in direct titrations of the polyUb ligands. Furthermore, the high sensitivity and large dynamic range of the sensor fluorescence readout allow for precise measurements even for very tight interactions (i.e., nanomolar Kd). Importantly, as demonstrated here with Ub2 and Ub3 ligands, the assay does not require labeling of either the receptor protein or the polyUb, and it can be used with polyUb ligands composed of virtually any Ub-Ub linkage type.
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Affiliation(s)
- Yun-Seok Choi
- Department of Biochemistry and Molecular Biology, Colorado State University, 1870 Campus Delivery, Fort Collins, Colorado 80523, United States
- School of Natural Sciences, Black Hills State University, Spearfish, South Dakota 57799, United States
| | - Sharon Lian
- Department of Biochemistry and Molecular Biology, Colorado State University, 1870 Campus Delivery, Fort Collins, Colorado 80523, United States
| | - Robert E. Cohen
- Department of Biochemistry and Molecular Biology, Colorado State University, 1870 Campus Delivery, Fort Collins, Colorado 80523, United States
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21
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Abstract
The prediction of reaction pathways for solid-solid transformations remains a key challenge. Here, we develop a pathway sampling method via swarm intelligence and graph theory and demonstrate that our pallas method is an effective tool to help understand phase transformations in solid-state systems. The method is capable of finding low-energy transition pathways between two minima without having to specify any details of the transition mechanism a priori. We benchmarked our pallas method against known phase transitions in cadmium selenide (CdSe) and silicon (Si). pallas readily identifies previously reported, low-energy phase transition pathways for the wurtzite to rock-salt transition in CdSe and reveals a novel lower-energy pathway that has not yet been observed. In addition, pallas provides detailed information that explains the complex phase transition sequence observed during the decompression of Si from high pressure. Given the efficiency to identify low-barrier-energy reaction pathways, the pallas methodology represents a promising tool for materials by design with valuable insights for novel synthesis.
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Affiliation(s)
- Li Zhu
- Geophysical Laboratory, Carnegie Institution for Science, 5251 Broad Branch Road, Northwest, Washington, DC 20015, United States
| | - R E Cohen
- Geophysical Laboratory, Carnegie Institution for Science, 5251 Broad Branch Road, Northwest, Washington, DC 20015, United States
- Department of Earth and Environmental Sciences, Ludwig Maximilians Universität, Munich 80333, Germany
| | - Timothy A Strobel
- Geophysical Laboratory, Carnegie Institution for Science, 5251 Broad Branch Road, Northwest, Washington, DC 20015, United States
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22
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Song K, Polak R, Zhang S, Rubner MF, Cohen RE, Askar KA. Reversible Self-Healing for Preserving Optical Transparency and Repairing Mechanical Damage in Composites. ACS Appl Mater Interfaces 2019; 11:12797-12807. [PMID: 30848876 DOI: 10.1021/acsami.9b00967] [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] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
This research concentrates on the healing of optical properties, roughness, contact angle hysteresis, and shallow scratches in polymer/nanoparticle composites. A series of ternary composite blends [epoxy/halloysite nanotubes (HNTs)/cellulose acetate butyrate (CAB)] with various CAB concentrations were fabricated and subjected to a series of mechanical damages. The optimized concentration of a nanoparticle is 1.0 vol %, and the CAB concentration is 3.0 vol % based on the mechanical reinforcement and wear resistance. Nanoscale scratching, microlevel falling-sand test, and macrolevel Taber abrasions were utilized to damage the surfaces. The induced damage (roughness and surface scratch up to hundreds of nanometers in depth) healed upon heating. At any temperatures above the softening transition of the semi-interpenetrating network structure of the polymer composites, CAB migrates into the microcracks, and the essential mechanical parameters (modulus, strength, strain to failure) are recovered; in our particular epoxy/HNTs/CAB system, optical transparency is also recovered efficiently. CAB also moves to the macroscopic air/specimen interface and favorably modifies the surface properties, reducing the roll-off angles of water droplets from ∼90° to ∼20°. Through an appropriate choice of CAB additives with different molecular weights, the healing temperature can be tailored.
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Affiliation(s)
- Kenan Song
- Department of Manufacturing Engineering, Ira A. Fulton Schools of Engineering , Arizona State University , 7001 East Williams Field Road , Mesa , Arizona 85212 , United States
| | | | | | | | | | - Khalid A Askar
- Department of Mechanical Engineering , Khalifa University of Science and Technology , P.O. Box 54224, Abu Dhabi , United Arab Emirates
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23
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Yerke LM, Cohen RE. Incidental Finding of a Suspected Horizontal Root Fracture During Mucogingival Surgery. Compend Contin Educ Dent 2019; 40:114-118. [PMID: 30767550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Periapical and bitewing radiographs lack the sensitivity to reliably diagnose horizontal root fractures, and, therefore, asymptomatic teeth with root fractures may remain undetected for years. This article reports a case in which a patient presented with a mucogingival defect on tooth No. 24 with no apparent history of dental trauma. During a free gingival graft procedure, a horizontal root fracture was observed in the apical third of the aforementioned tooth. After the clinician communicated this finding to the patient, the patient recollected two instances of trauma that had occurred to this area more than 30 years earlier. The presence of the horizontal root fracture did not affect the postoperative healing from the mucogingival procedure, and the tooth remained stable at the 1-year follow-up.
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Affiliation(s)
- Lisa M Yerke
- Clinical Assistant Professor, School of Dental Medicine, Department of Periodontics and Endodontics, University at Buffalo, State University of New York, Buffalo, New York; Private Practice, East Amherst, New York
| | - Robert E Cohen
- Professor, School of Dental Medicine, Department of Periodontics and Endodontics, University at Buffalo, State University of New York, Buffalo, New York
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24
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Zhang H, Yavorsky BY, Cohen RE. Polar Metallocenes. Molecules 2019; 24:molecules24030486. [PMID: 30700050 PMCID: PMC6384802 DOI: 10.3390/molecules24030486] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Revised: 01/23/2019] [Accepted: 01/26/2019] [Indexed: 11/16/2022] Open
Abstract
Crystalline polar metallocenes are potentially useful active materials as piezoelectrics, ferroelectrics, and multiferroics. Within density functional theory (DFT), we computed structural properties, energy differences for various phases, molecular configurations, and magnetic states, computed polarizations for different polar crystal structures, and computed dipole moments for the constituent molecules with a Wannier function analysis. Of the systems studied, Mn2(C9H9N)2 is the most promising as a multiferroic material, since the ground state is both polar and ferromagnetic. We found that the predicted crystalline polarizations are 30–40% higher than the values that would be obtained from the dipole moments of the isolated constituent molecules, due to the local effects of the self-consistent internal electric field, indicating high polarizabilities.
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Affiliation(s)
- Haiwu Zhang
- Department of Earth and Environmental Sciences, Ludwig-Maximilians Universität München, Theresienstr., 41 80333 Munich, Germany.
| | - B Yu Yavorsky
- Department of Earth and Environmental Sciences, Ludwig-Maximilians Universität München, Theresienstr., 41 80333 Munich, Germany.
| | - R E Cohen
- Department of Earth and Environmental Sciences, Ludwig-Maximilians Universität München, Theresienstr., 41 80333 Munich, Germany.
- Extreme Materials Initiative, Geophysical Laboratory, Carnegie Institution for Science, Washington, DC 20015, USA.
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25
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Xu J, Zhang P, Haule K, Minar J, Wimmer S, Ebert H, Cohen RE. Thermal Conductivity and Electrical Resistivity of Solid Iron at Earth's Core Conditions from First Principles. Phys Rev Lett 2018; 121:096601. [PMID: 30230853 DOI: 10.1103/physrevlett.121.096601] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Indexed: 06/08/2023]
Abstract
We compute the thermal conductivity and electrical resistivity of solid hcp Fe to pressures and temperatures of Earth's core. We find significant contributions from electron-electron scattering, usually neglected at high temperatures in transition metals. Our calculations show a quasilinear relation between the electrical resistivity and temperature for hcp Fe at extreme high pressures. We obtain thermal and electrical conductivities that are consistent with experiments considering reasonable error. The predicted thermal conductivity is reduced from previous estimates that neglect electron-electron scattering. Our estimated thermal conductivity for the outer core is 77±10 W m^{-1} K^{-1} and is consistent with a geodynamo driven by thermal convection.
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Affiliation(s)
- Junqing Xu
- Department of Earth and Environmental Sciences, LMU Munich, Theresienstrasse 41, 80333 Munich, Germany
| | - Peng Zhang
- School of Science, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - K Haule
- Department of Physics, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Jan Minar
- University of West Bohemia, New Technologies-Research Centre, Pilsen, Czech Republic
| | - Sebastian Wimmer
- Department Chemie, Physikalische Chemie, University of Munich, D-81377 Munich, Germany
| | - Hubert Ebert
- Department Chemie, Physikalische Chemie, University of Munich, D-81377 Munich, Germany
| | - R E Cohen
- Department of Earth and Environmental Sciences, LMU Munich, Theresienstrasse 41, 80333 Munich, Germany
- Extreme Materials Initiative, Geophysical Laboratory, Carnegie Institution for Science, Washington, D.C. 20015-1305, USA
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26
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Taketa TB, Dos Santos DM, Fiamingo A, Vaz JM, Beppu MM, Campana-Filho SP, Cohen RE, Rubner MF. Investigation of the Internal Chemical Composition of Chitosan-Based LbL Films by Depth-Profiling X-ray Photoelectron Spectroscopy (XPS) Analysis. Langmuir 2018; 34:1429-1440. [PMID: 29307187 DOI: 10.1021/acs.langmuir.7b04104] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Chitosan-based thin films were assembled using the layer-by-layer technique, and the axial composition was accessed using X-ray photoelectron spectroscopy with depth profiling. Chitosan (CHI) samples possessing different degrees of acetylation ([Formula: see text]) and molecular weight ([Formula: see text]) produced via the ultrasound-assisted deacetylation reaction were used in this study along with two different polyanions, namely, sodium polystyrenesulfonate (PSS) and carboxymethylcellulose (CMC). When chitosan, a positively charged polymer in aqueous acid medium, was combined with a strong polyanion (PSS), the total positive charge of chitosan, directly related to its [Formula: see text], was the key factor affecting the film formation. However, for CMC/CHI films, the pH of the medium and [Formula: see text] of chitosan strongly affected the film structure and composition. Consequently, the structure and the axial composition of chitosan-based films can be finely adjusted by choosing the polyanion and defining the chitosan to be used according to its DA and [Formula: see text] for the desired application, as demonstrated by the antibacterial tests.
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Affiliation(s)
- Thiago B Taketa
- School of Chemical Engineering, University of Campinas , 13083-852 SP, Campinas, Brazil
| | - Danilo M Dos Santos
- São Carlos Institute of Chemistry, University of São Paulo , 13010-111 SP, São Paulo, Brazil
| | - Anderson Fiamingo
- São Carlos Institute of Chemistry, University of São Paulo , 13010-111 SP, São Paulo, Brazil
| | - Juliana M Vaz
- School of Chemical Engineering, University of Campinas , 13083-852 SP, Campinas, Brazil
| | - Marisa M Beppu
- School of Chemical Engineering, University of Campinas , 13083-852 SP, Campinas, Brazil
| | - Sérgio P Campana-Filho
- São Carlos Institute of Chemistry, University of São Paulo , 13010-111 SP, São Paulo, Brazil
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27
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Wu HH, Cohen RE. Polarization rotation and the electrocaloric effect in barium titanate. J Phys Condens Matter 2017; 29:485704. [PMID: 29052555 DOI: 10.1088/1361-648x/aa94db] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We study the electrocaloric effect in the classic ferroelectric BaTiO3 through a series of phase transitions driven by applied electric field and temperature. We find both negative and positive electrocaloric effects, with the negative electrocaloric effect, where temperature decreases with applied field, in monoclinic phases. Macroscopic polarization rotation is evident through the monoclinic and orthorhombic phases under applied field, and is responsible for the negative electrocaloric effect.
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Affiliation(s)
- H H Wu
- Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität, Munich 80333, Germany
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28
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Abstract
Piezoelectrics with negative longitudinal piezoelectric coefficients will contract in the direction of an applied electric field. Such piezoelectrics are thought to be rare, but there is no fundamental physics preventing the realization of negative longitudinal piezoelectric effect in a single-phase material. Using first-principles calculations, we demonstrate that several hexagonal ABC ferroelectrics possess significant negative longitudinal piezoelectric effects. The data mining of a first-principles-based database of piezoelectrics reveals that this effect is a general phenomenon. The origin of this unusual piezoelectric response relies on the strong ionic bonds associated with small effective charges and rigid potential energy surfaces. Moreover, ferroelectrics with negative longitudinal piezoelectric coefficients show anomalous pressure-enhanced ferroelectricity. Our results offer design principles to aid the search for new piezoelectrics for novel electromechanical device applications.
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Affiliation(s)
- Shi Liu
- Extreme Materials Initiative, Geophysical Laboratory, Carnegie Institution for Science, Washington, DC 20015-1305, USA
| | - R E Cohen
- Extreme Materials Initiative, Geophysical Laboratory, Carnegie Institution for Science, Washington, DC 20015-1305, USA
- Department of Earth- and Environmental Sciences, Ludwig Maximilians Universität, Munich 80333, Germany
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Chapman JBJ, Cohen RE, Kimmel AV, Duffy DM. Improving the Functional Control of Aged Ferroelectrics Using Insights from Atomistic Modeling. Phys Rev Lett 2017; 119:177602. [PMID: 29219448 DOI: 10.1103/physrevlett.119.177602] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Indexed: 06/07/2023]
Abstract
We provide a fundamental insight into the microscopic mechanisms of the aging processes. Using large-scale molecular dynamics simulations of the prototypical ferroelectric material PbTiO_{3}, we demonstrate that the experimentally observed aging phenomena can be reproduced from intrinsic interactions of defect dipoles related to dopant-vacancy associates, even in the absence of extrinsic effects. We show that variation of the dopant concentration modifies the material's hysteretic response. We identify a universal method to reduce loss and tune the electromechanical properties of inexpensive ceramics for efficient technologies.
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Affiliation(s)
- J B J Chapman
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, United Kingdom
| | - R E Cohen
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
- Extreme Materials Initiative, Geophysical Laboratory, Carnegie Institution of Washington, Washington, D.C. 20015, USA
- Ludwig Maximilians University Munich, 80539 München, Germany
| | - A V Kimmel
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - D M Duffy
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
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Klyachko NL, Polak R, Haney MJ, Zhao Y, Gomes Neto RJ, Hill MC, Kabanov AV, Cohen RE, Rubner MF, Batrakova EV. Macrophages with cellular backpacks for targeted drug delivery to the brain. Biomaterials 2017; 140:79-87. [PMID: 28633046 PMCID: PMC5605925 DOI: 10.1016/j.biomaterials.2017.06.017] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 06/08/2017] [Accepted: 06/15/2017] [Indexed: 01/24/2023]
Abstract
Most potent therapeutics are unable to cross the blood-brain barrier following systemic administration, which necessitates the development of unconventional, clinically applicable drug delivery systems. With the given challenges, biologically active vehicles are crucial to accomplishing this task. We now report a new method for drug delivery that utilizes living cells as vehicles for drug carriage across the blood brain barrier. Cellular backpacks, 7-10 μm diameter polymer patches of a few hundred nanometers in thickness, are a potentially interesting approach, because they can act as drug depots that travel with the cell-carrier, without being phagocytized. Backpacks loaded with a potent antioxidant, catalase, were attached to autologous macrophages and systemically administered into mice with brain inflammation. Using inflammatory response cells enabled targeted drug transport to the inflamed brain. Furthermore, catalase-loaded backpacks demonstrated potent therapeutic effects deactivating free radicals released by activated microglia in vitro. This approach for drug carriage and release can accelerate the development of new drug formulations for all the neurodegenerative disorders.
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Affiliation(s)
- Natalia L Klyachko
- Center for Nanotechnology in Drug Delivery, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Department of Chemical Enzymology, Faculty of Chemistry, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - Roberta Polak
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Matthew J Haney
- Center for Nanotechnology in Drug Delivery, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Yuling Zhao
- Center for Nanotechnology in Drug Delivery, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Reginaldo J Gomes Neto
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Michael C Hill
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Alexander V Kabanov
- Center for Nanotechnology in Drug Delivery, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Department of Chemical Enzymology, Faculty of Chemistry, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - Robert E Cohen
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Michael F Rubner
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Elena V Batrakova
- Center for Nanotechnology in Drug Delivery, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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Abstract
Charge-neutral 180° domain walls that separate domains of antiparallel polarization directions are common structural topological defects in ferroelectrics. In normal ferroelectrics, charged 180° domain walls running perpendicular to the polarization directions are highly energetically unfavorable because of the depolarization field and are difficult to stabilize. We explore both neutral and charged 180° domain walls in hyperferroelectrics, a class of proper ferroelectrics with persistent polarization in the presence of a depolarization field, using density functional theory. We obtain zero temperature equilibrium structures of head-to-head and tail-to-tail walls in recently discovered ABC-type hexagonal hyperferroelectrics. Charged domain walls can also be stabilized in canonical ferroelectrics represented by LiNbO3 without any dopants, defects or mechanical clamping. First-principles electronic structure calculations show that charged domain walls can reduce and even close the band gap of host materials and support quasi-two-dimensional electron(hole) gas with enhanced electrical conductivity.
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Affiliation(s)
- S Liu
- Extreme Materials Initiative, Geophysical Laboratory, Carnegie Institution for Science, Washington, DC 20015-1305, United States of America
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Yerke LM, Jamjoom A, Zahid TM, Cohen RE. The Effect of Platelet-Rich Fibrin, Calcium Sulfate Hemihydrate, Platelet-Rich Plasma and Resorbable Collagen on Soft Tissue Closure of Extraction Sites. J Funct Biomater 2017; 8:jfb8020017. [PMID: 28587096 PMCID: PMC5491998 DOI: 10.3390/jfb8020017] [Citation(s) in RCA: 7] [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] [Received: 04/24/2017] [Revised: 05/16/2017] [Accepted: 05/22/2017] [Indexed: 11/16/2022] Open
Abstract
Rapid and complete soft tissue healing after tooth extraction minimizes surgical complications and facilitates subsequent implant placement. We used four treatment methods and assessed changes in soft tissue socket closure following tooth extraction in humans. The effects of platelet-rich fibrin-calcium sulfate hemihydrate (PRF-CSH), platelet-rich plasma-calcium sulfate hemihydrate (PRP-CSH), a resorbable collagen dressing (RCD), and no grafting material were compared in a randomized, controlled pilot study with a blinded parallel design (N = 23). Patients with a hopeless tooth scheduled for extraction were randomly assigned to one of the four treatment groups. Socket measurements were obtained immediately after extraction and treatment, as well as after 21 days. There was a significant decrease in the total epithelialized external surface area of the extraction sockets in each group at all time points. However, there were no significant differences in soft tissue closure (p > 0.05) at any time point and PRF-CSH or PRP-CSH did not provide any additional benefit to enhance the soft tissue closure of extraction sockets compared with either RCD or sites without graft.
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Affiliation(s)
- Lisa M Yerke
- Department of Periodontics and Endodontics, School of Dental Medicine, University at Buffalo, State University of New York, 250 Squire Hall, Buffalo, NY 14214, USA.
| | - Amal Jamjoom
- Department of Periodontics and Endodontics, School of Dental Medicine, University at Buffalo, State University of New York, 250 Squire Hall, Buffalo, NY 14214, USA.
| | - Talal M Zahid
- Department of Periodontology, King Abdulaziz University, University District, Jeddah 22252, Saudi Arabia.
| | - Robert E Cohen
- Department of Periodontics and Endodontics, School of Dental Medicine, University at Buffalo, State University of New York, 250 Squire Hall, Buffalo, NY 14214, USA.
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Choi HJ, Park KC, Lee H, Crouzier T, Rubner MF, Cohen RE, Barbastathis G, McKinley GH. Superoleophilic Titania Nanoparticle Coatings with Fast Fingerprint Decomposition and High Transparency. ACS Appl Mater Interfaces 2017; 9:8354-8360. [PMID: 28164702 DOI: 10.1021/acsami.6b14631] [Citation(s) in RCA: 7] [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] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Low surface tension sebaceous liquids such as human fingerprint oils are readily deposited on high energy surfaces such as clean glass, leaving smudges that significantly lower transparency. There have been several attempts to prevent formation of these dactylograms on glass by employing oil-repellent textured surfaces. However, nanotextured superoleophobic coatings typically scatter visible light, and the intrinsic thermodynamic metastability of the composite superoleophobic state can result in failure of the oil repellency under moderate contact pressure. We develop titania-based porous nanoparticle coatings that are superoleophilic and highly transparent and which exhibit short time scales for decomposition of fingerprint oils under ultraviolet light. The mechanism by which a typical dactylogram is consumed combines wicking of the sebum into the nanoporous titania structure followed by photocatalytic degradation. We envision a wide range of applications because these TiO2 nanostructured surfaces remain photocatalytically active against fingerprint oils in natural sunlight and are also compatible with flexible glass substrates.
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Affiliation(s)
| | | | | | | | | | | | - George Barbastathis
- Singapore-MIT Alliance for Research and Technology (SMART) Centre, Singapore
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Abstract
It is known that smooth, hydrophobic solid surfaces exhibit low ice adhesion values, which have been shown to approach a lower ice adhesion strength limit (∼150 kPa) defined by the water receding contact angle. To overcome this limit, we have designed self-lubricating icephobic coatings by blending polydimethylsiloxane (PDMS)-poly(ethylene glycol) (PEG) amphiphilic copolymers into a polymer matrix. Such coatings provide low ice adhesion strength values (∼50 kPa) that can substantially reduce the lower bound of the ice adhesion strength achieved previously on smooth, hydrophobic solid surfaces. Different molecular mechanisms are responsible for the low ice adhesion strength attained by these two approaches. For the smooth hydrophobic surfaces, an increased water depletion layer thickness at the interface weakens the van der Waals' interactions between the ice and the polymeric substrate. For the self-lubricating icephobic coatings, the PEG component of the amphiphilic copolymer is capable of strongly hydrogen bonding with water molecules. The surface hydrogen-bonded water molecules do not freeze, even at substantial levels of subcooling, and therefore serve as a self-lubricating interfacial liquid-like layer that helps to reduce the adhesion strength of ice to the surface. The existence of nonfrozen water molecules at the ice-solid interface is confirmed by solid-state nuclear magnetic resonance (NMR) spectroscopy.
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Affiliation(s)
- Dayong Chen
- Department of Chemical Engineering, Massachusetts Institute of Technology
- Department of Mechanical Engineering, Massachusetts Institute of Technology
| | | | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology
| | - Robert E. Cohen
- Department of Chemical Engineering, Massachusetts Institute of Technology
- Corresponding authors: Robert E. Cohen, Fax: 01 617 258 8224. , Gareth H. McKinley, Fax: 01 617 258 8559.
| | - Gareth H. McKinley
- Department of Mechanical Engineering, Massachusetts Institute of Technology
- Corresponding authors: Robert E. Cohen, Fax: 01 617 258 8224. , Gareth H. McKinley, Fax: 01 617 258 8559.
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Song K, Chen D, Polak R, Rubner MF, Cohen RE, Askar KA. Enhanced Wear Resistance of Transparent Epoxy Composite Coatings with Vertically Aligned Halloysite Nanotubes. ACS Appl Mater Interfaces 2016; 8:35552-35564. [PMID: 27976847 DOI: 10.1021/acsami.6b11872] [Citation(s) in RCA: 9] [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] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The influence of nanoparticle orientation on wear resistance of transparent composite coatings has been studied. Using a nozzle spray coating method, halloysite nanotubes (HNTs) were aligned in the in-plane and out-of-plane directions and in various randomly oriented states. Nanoscratching, falling sand, and Taber Abrasion tests were used to characterize the wear resistance at different length scales. Composites consistently displayed better wear resistance than pure epoxy. Samples with out-of-plane particle orientations exhibited better wear-resistant behavior than those with in-plane particle distributions. In nanoscratching tests, the out-of-plane orientation decreases the normalized scratch volume by as much as 60% compared to pure epoxy. In the falling sand and Taber Abrasion tests, out-of-plane aligned halloysite particles resulted in surfaces with smaller roughness based on stylus profilometry and SEM observations. The decrease in roughness values after these wear tests can be as large as 67% from pure epoxy to composites. Composites with higher out-of-plane particle orientation factors exhibited better light transmittance after sand impingements and other wear tests. This study suggests a useful strategy for producing material systems with enhanced mechanical durability and more durable optical properties.
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Affiliation(s)
- Kenan Song
- Department of Chemical Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Ave., Cambridge, Massachusetts 02139, United States
- Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Ave., Cambridge, Massachusetts 02139, United States
| | - Dayong Chen
- Department of Chemical Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Ave., Cambridge, Massachusetts 02139, United States
- Department of Mechanical Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Ave., Cambridge, Massachusetts 02139, United States
| | - Roberta Polak
- Department of Chemical Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Ave., Cambridge, Massachusetts 02139, United States
- Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Ave., Cambridge, Massachusetts 02139, United States
| | - Michael F Rubner
- Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Ave., Cambridge, Massachusetts 02139, United States
- Center for Materials Science and Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Ave., Cambridge, Massachusetts 02139, United States
| | - Robert E Cohen
- Department of Chemical Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Ave., Cambridge, Massachusetts 02139, United States
| | - Khalid A Askar
- Department of Materials Science and Engineering, Masdar Institute of Science and Technology , P.O. Box 54224 Abu Dhabi, United Arab Emirates
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Cohen RE, Creticos PS, Norman PS. The Effects of Guided Imagery (GI) on Allergic Subjects' Responses to Ragweed-Pollen Nasal Challenge: An Exploratory Investigation. ACTA ACUST UNITED AC 2016. [DOI: 10.2190/56uu-uqpc-r2ga-c651] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study investigated the effects of guided imagery (GI) on allergic subjects' responses to ragweed-pollen nasal challenge. Complete data was obtained for fourteen subjects ranging from twenty-one to sixty-two years of age. Nasal challenges were performed before and after GI. Dependent variables consisted of two biochemical mediators obtained from nasal secretions and two subject-reported measures of symptoms, respectively: TAME (tosylarginine methyl ester)-esterase; histamine; severity of symptoms (e.g., nasal congestion); and numbers of sneezes. An experimental group ( n = 7) participated in a three-week program of GI designed to promote relaxation, psychosynthesis, and modulation of immunological activity at the cellular level. A posttreatment, between-groups analysis of the experimental group and a no-contact control group ( n = 7) determined that treatment significantly suppressed TAME-esterase release ( p < .03). Thereafter, the control group participated in the treatment program, and a posttreatment, within-group analysis also indicated significantly suppressed TAME-esterase release ( p < .05). A two-week, follow-up nasal challenge administered to the experimental group indicated maintenance of suppressed TAME-esterase release ( p < .03) and reduced severity of symptoms ( p < .05).
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Affiliation(s)
| | - Peter S. Creticos
- The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Philip S. Norman
- The Johns Hopkins University School of Medicine, Baltimore, Maryland
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Saranadhi D, Chen D, Kleingartner JA, Srinivasan S, Cohen RE, McKinley GH. Sustained drag reduction in a turbulent flow using a low-temperature Leidenfrost surface. Sci Adv 2016; 2:e1600686. [PMID: 27757417 PMCID: PMC5065253 DOI: 10.1126/sciadv.1600686] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 08/31/2016] [Indexed: 05/24/2023]
Abstract
Skin friction drag contributes a major portion of the total drag for small and large water vehicles at high Reynolds number (Re). One emerging approach to reducing drag is to use superhydrophobic surfaces to promote slip boundary conditions. However, the air layer or "plastron" trapped on submerged superhydrophobic surfaces often diminishes quickly under hydrostatic pressure and/or turbulent pressure fluctuations. We use active heating on a superhydrophobic surface to establish a stable vapor layer or "Leidenfrost" state at a relatively low superheat temperature. The continuous film of water vapor lubricates the interface, and the resulting slip boundary condition leads to skin friction drag reduction on the inner rotor of a custom Taylor-Couette apparatus. We find that skin friction can be reduced by 80 to 90% relative to an unheated superhydrophobic surface for Re in the range 26,100 ≤ Re ≤ 52,000. We derive a boundary layer and slip theory to describe the hydrodynamics in the system and show that the plastron thickness is h = 44 ± 11 μm, in agreement with expectations for a Leidenfrost surface.
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Affiliation(s)
- Dhananjai Saranadhi
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Dayong Chen
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Justin A. Kleingartner
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Siddarth Srinivasan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Robert E. Cohen
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Gareth H. McKinley
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Song K, Polak R, Chen D, Rubner MF, Cohen RE, Askar KA. Spray-Coated Halloysite-Epoxy Composites: A Means To Create Mechanically Robust, Vertically Aligned Nanotube Composites. ACS Appl Mater Interfaces 2016; 8:20396-20406. [PMID: 27428814 DOI: 10.1021/acsami.6b06174] [Citation(s) in RCA: 5] [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: 06/06/2023]
Abstract
Halloysite nanotube-filled epoxy composites were fabricated using spray-coating methods. The halloysite nanotubes (HNTs) were aligned by the hydrodynamic flow conditions at the spray nozzle, and the polymer viscosity helped to preserve this preferential orientation in the final coatings on the target substrates. Electron microscopy demonstrated a consistent trend of higher orientation degree in the nanocomposite coatings as viscosity increased. The nanoindentation mechanical performances of these coatings were studied using a Hysitron TriboIndenter device. Composites showed improvements up to ∼50% in modulus and ∼100% in hardness as compared to pure epoxy, and the largest improvements in mechanical performance correlated with higher alignment of HNTs along the plane-normal direction. Achieving this nanotube alignment using a simple spray-coating method suggests potential for large-scale production of multifunctional anisotropic nanocomposite coatings on a variety of rigid and deformable substrates.
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Affiliation(s)
- Kenan Song
- Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States
- Department of Chemical Engineering, Massachusetts Institute of Technology , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States
- Department of Mechanical Engineering, Massachusetts Institute of Technology , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States
| | - Roberta Polak
- Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States
- Department of Chemical Engineering, Massachusetts Institute of Technology , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States
- Department of Mechanical Engineering, Massachusetts Institute of Technology , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States
| | - Dayong Chen
- Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States
- Department of Chemical Engineering, Massachusetts Institute of Technology , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States
- Department of Mechanical Engineering, Massachusetts Institute of Technology , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States
| | - Michael F Rubner
- Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States
| | - Robert E Cohen
- Department of Chemical Engineering, Massachusetts Institute of Technology , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States
| | - Khalid A Askar
- Department of Materials Science and Engineering, Masdar Institute of Science and Technology , Abu Dhabi, United Arab Emirates
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Abstract
Surfaces with patterned wettability contrast are important in industrial applications such as heat transfer, water collection, and particle separation. Traditional methods of fabricating such surfaces rely on microfabrication technologies, which are only applicable to certain substrates and are difficult to scale up and implement on curved surfaces. By taking advantage of a mechanical instability on a polyurethane elastomer film, we show that wettability patterns on both flat and curved surfaces can be generated spontaneously via a simple dip coating process. Variations in dipping time, sample prestress, and chemical treatment enable independent control of domain size (from about 100 to 500 μm), morphology, and wettability contrast, respectively. We characterize the wettability contrast using local surface energy measurements via the sessile droplet technique and tensiometry.
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Affiliation(s)
- Dayong Chen
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Gareth H McKinley
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Robert E Cohen
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139;
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Abstract
We report an accurate study of interactions between benzene molecules using variational quantum Monte Carlo (VMC) and diffusion quantum Monte Carlo (DMC) methods. We compare these results with density functional theory using different van der Waals functionals. In our quantum Monte Carlo (QMC) calculations, we use accurate correlated trial wave functions including three-body Jastrow factors and backflow transformations. We consider two benzene molecules in the parallel displaced geometry, and find that by highly optimizing the wave function and introducing more dynamical correlation into the wave function, we compute the weak chemical binding energy between aromatic rings accurately. We find optimal VMC and DMC binding energies of -2.3(4) and -2.7(3) kcal/mol, respectively. The best estimate of the coupled-cluster theory through perturbative triplets/complete basis set limit is -2.65(2) kcal/mol [Miliordos et al., J. Phys. Chem. A 118, 7568 (2014)]. Our results indicate that QMC methods give chemical accuracy for weakly bound van der Waals molecular interactions, comparable to results from the best quantum chemistry methods.
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Affiliation(s)
- Sam Azadi
- Department of Earth Science and Thomas Young Centre, University College London, London WC1E 6BT, United Kingdom
| | - R E Cohen
- London Centre for Nanotechnology, University College London, London WC1E 6BT, United Kingdom and Extreme Materials Initiative, Geophysical Laboratory, Carnegie Institution of Washington, Washington, D.C. 20015, USA
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Dorman TA, Cohen RE, Dasig D, Jeng S, Fischer N, de Jong A. Energy Efficiency During Human Walking Before and After Prolotherapy. ACTA ACUST UNITED AC 2016. [DOI: 10.1080/1355297x.1995.11719775] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Abellán D, Nart J, Pascual A, Cohen RE, Sanz-Moliner JD. Physical and Mechanical Evaluation of Five Suture Materials on Three Knot Configurations: An in Vitro Study. Polymers (Basel) 2016; 8:E147. [PMID: 30979247 PMCID: PMC6432448 DOI: 10.3390/polym8040147] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [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: 12/04/2015] [Revised: 03/21/2016] [Accepted: 03/25/2016] [Indexed: 11/24/2022] Open
Abstract
The aim of this study was to evaluate and compare the mechanical properties of five suture materials on three knot configurations when subjected to different physical conditions. Five 5-0 (silk, polyamide 6/66, polyglycolic acid, glycolide-e-caprolactone copolymer, polytetrafluoroethylene) suture materials were used. Ten samples per group of each material were used. Three knot configurations were compared A.2=1=1 (forward⁻forward⁻reverse), B.2=1=1 (forward⁻reverse⁻forward), C.1=2=1 (forward⁻forward⁻reverse). Mechanical properties (failure load, elongation, knot slippage/breakage) were measured using a universal testing machine. Samples were immersed in three different pH concentrations (4,7,9) at room temperature for 7 and 14 days. For the thermal cycle process, sutures were immersed in two water tanks at different temperatures (5 and 55 °C). Elongation and failure load were directly dependent on the suture material. Polyglycolic acid followed by glycolide-e-caprolactone copolymer showed the most knot failure load, while polytetrafluoroethylene showed the lowest (P < 0.001). Physical conditions had no effect on knot failure load (P = 0.494). Statistically significant differences were observed between knot configurations (P = 0.008). Additionally, individual assessment of suture material showed statistically significant results for combinations of particular knot configurations. Physical conditions, such as pH concentration and thermal cycle process, have no influence on suture mechanical properties. However, knot failure load depends on the suture material and knot configuration used. Consequently, specific suturing protocols might be recommended to obtain higher results of knot security.
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Affiliation(s)
- Desire Abellán
- Department of Periodontics, School of Dentistry, Universitat Internacional de Catalunya (UIC), Barcelona 08195, Spain.
| | - José Nart
- Department of Periodontics, School of Dentistry, Universitat Internacional de Catalunya (UIC), Barcelona 08195, Spain.
| | - Andrés Pascual
- Department of Periodontics, School of Dentistry, Universitat Internacional de Catalunya (UIC), Barcelona 08195, Spain.
| | - Robert E Cohen
- Department of Periodontics and Endodontics, University at Buffalo, Buffalo 14260, NY, USA.
| | - Javier D Sanz-Moliner
- Department of Periodontics, School of Dentistry, Universitat Internacional de Catalunya (UIC), Barcelona 08195, Spain.
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Polak R, Lim RM, Beppu MM, Pitombo RNM, Cohen RE, Rubner MF. Liposome-Loaded Cell Backpacks. Adv Healthc Mater 2015; 4:2832-41. [PMID: 26616471 DOI: 10.1002/adhm.201500604] [Citation(s) in RCA: 31] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 09/22/2015] [Indexed: 12/19/2022]
Abstract
Cell backpacks, or micron-scale patches of a few hundred nanometers in thickness fabricated by layer-by-layer (LbL) assembly, are potentially useful vehicles for targeted drug delivery on the cellular level. In this work, echogenic liposomes (ELIPs) containing the anticancer drug doxorubicin (DOX) are embedded into backpacks through electrostatic interactions and LbL assembly. Poly(allylamine hydrochloride)/poly(acrylic acid) (PAH/PAA)n , and poly(diallyldimethylammonium chloride)/poly(styrene sulfonate) (PDAC/SPS)n film systems show the greatest ELIP incorporation of the films studied while maintaining the structural integrity of the vesicles. The use of ELIPs for drug encapsulation into backpacks facilitates up to three times greater DOX loading compared to backpacks without ELIPs. Cytotoxicity studies reveal that monocyte backpack conjugates remain viable even after 72 h, demonstrating promise as drug delivery vehicles. Because artificial vesicles can load many different types of drugs, ELIP containing backpacks offer a unique versatility for broadening the range of possible applications for cell backpacks.
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Affiliation(s)
- Roberta Polak
- School of Pharmaceutical Sciences; University of Sao Paulo; USP Sao Paulo SP 05508-900 Brazil
- Department of Materials Science and Engineering; Massachusetts Institute of Technology (MIT); Cambridge M,A 02139 USA
| | - Rosanna M. Lim
- Department of Chemical Engineering; Massachusetts Institute of Technology (MIT); Cambridge MA 02139 USA
| | - Marisa M. Beppu
- School of Chemical Engineering; University of Campinas; UNICAMP; Campinas SP 13083-852 Brazil
| | - Ronaldo N. M. Pitombo
- School of Pharmaceutical Sciences; University of Sao Paulo; USP Sao Paulo SP 05508-900 Brazil
| | - Robert E. Cohen
- Department of Chemical Engineering; Massachusetts Institute of Technology (MIT); Cambridge MA 02139 USA
| | - Michael F. Rubner
- Department of Materials Science and Engineering; Massachusetts Institute of Technology (MIT); Cambridge M,A 02139 USA
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Polak R, Lim RM, Beppu MM, Pitombo RNM, Cohen RE, Rubner MF. Targeted Drug Delivery: Liposome-Loaded Cell Backpacks (Adv. Healthcare Mater. 18/2015). Adv Healthc Mater 2015. [DOI: 10.1002/adhm.201570104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Roberta Polak
- School of Pharmaceutical Sciences; University of Sao Paulo; USP Sao Paulo SP 05508-900 Brazil
- Department of Materials Science and Engineering; Massachusetts Institute of Technology (MIT); Cambridge M,A 02139 USA
| | - Rosanna M. Lim
- Department of Chemical Engineering; Massachusetts Institute of Technology (MIT); Cambridge MA 02139 USA
| | - Marisa M. Beppu
- School of Chemical Engineering; University of Campinas; UNICAMP; Campinas SP 13083-852 Brazil
| | - Ronaldo N. M. Pitombo
- School of Pharmaceutical Sciences; University of Sao Paulo; USP Sao Paulo SP 05508-900 Brazil
| | - Robert E. Cohen
- Department of Chemical Engineering; Massachusetts Institute of Technology (MIT); Cambridge MA 02139 USA
| | - Michael F. Rubner
- Department of Materials Science and Engineering; Massachusetts Institute of Technology (MIT); Cambridge M,A 02139 USA
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Kleingartner JA, Srinivasan S, Truong QT, Sieber M, Cohen RE, McKinley GH. Designing Robust Hierarchically Textured Oleophobic Fabrics. Langmuir 2015; 31:13201-13213. [PMID: 26473386 DOI: 10.1021/acs.langmuir.5b03000] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Commercially available woven fabrics (e.g., nylon- or PET-based fabrics) possess inherently re-entrant textures in the form of cylindrical yarns and fibers. We analyze the liquid repellency of woven and nanotextured oleophobic fabrics using a nested model with n levels of hierarchy that is constructed from modular units of cylindrical and spherical building blocks. At each level of hierarchy, the density of the topographical features is captured using a dimensionless textural parameter D(n)*. For a plain-woven mesh comprised of chemically treated fiber bundles (n = 2), the tight packing of individual fibers in each bundle (D2* ≈ 1) imposes a geometric constraint on the maximum oleophobicity that can be achieved solely by modifying the surface energy of the coating. For liquid droplets contacting such tightly bundled fabrics with modified surface energies, we show that this model predicts a lower bound on the equilibrium contact angle of θ(E) ≈ 57° below which the Cassie–Baxter to Wenzel wetting transition occurs spontaneously, and this is validated experimentally. We demonstrate how the introduction of an additional higher order micro-/nanotexture onto the fibers (n = 3) is necessary to overcome this limit and create more robustly nonwetting fabrics. Finally, we show a simple experimental realization of the enhanced oleophobicity of fabrics by depositing spherical microbeads of poly(methyl methacrylate)/fluorodecyl polyhedral oligomeric silsesquioxane (fluorodecyl POSS) onto the fibers of a commercial woven nylon fabric.
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Affiliation(s)
| | | | - Quoc T Truong
- Research, Development and Engineering Command, U.S. Army Natick Soldier, Research, Development and Engineering Center , Natick, Massachusetts 01760, United States
| | - Michael Sieber
- Research, Development and Engineering Command, U.S. Army Natick Soldier, Research, Development and Engineering Center , Natick, Massachusetts 01760, United States
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Abstract
Alveolar ridge bone resorption is a biologic phenomenon that occurs following tooth extraction and cannot be prevented. This paper reviews the vertical and horizontal ridge dimensional changes that are associated with tooth extraction. It also provides an overview of the advantages of ridge preservation as well as grafting materials. A Medline search among English language papers was performed in March 2015 using alveolar ridge preservation, ridge augmentation, and various graft types as search terms. Additional papers were considered following the preliminary review of the initial search that were relevant to alveolar ridge preservation. The literature suggests that ridge preservation methods and augmentation techniques are available to minimize and restore available bone. Numerous grafting materials, such as autografts, allografts, xenografts, and alloplasts, currently are used for ridge preservation. Other materials, such as growth factors, also can be used to enhance biologic outcome.
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Affiliation(s)
- Amal Jamjoom
- Department of Periodontics, State University of New York at Buffalo, Buffalo, NY 14214, USA.
| | - Robert E Cohen
- Department of Periodontics, State University of New York at Buffalo, Buffalo, NY 14214, USA.
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Polak R, Bradwell GM, Gilbert JB, Danielsen S, Beppu MM, Cohen RE, Rubner MF. Optimization of amine-rich multilayer thin films for the capture and quantification of prostate-specific antigen. Langmuir 2015; 31:5479-5488. [PMID: 25909861 DOI: 10.1021/acs.langmuir.5b00443] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
It is demonstrated that poly(allylamine hydrochloride)/poly(styrenesulfonate) (PAH/SPS) multilayer films can be successfully tailored for the capture and detection of small biomolecules in dilute concentrations. Based on in vitro results, these films could be potentially applied for rapid and high-throughput diagnosis of dilute biomarkers in serum or tissue. PAH presents functional amino groups that can be further reacted with desired chemistries in order to create customizable and specific surfaces for biomolecule capture. A variety of film assembly characteristics were tested (pH, molecular weight of PAH, and ionic strength) to tune the biotinylation and swelling behavior of these films to maximize detection capabilities. The resultant optimized biotinylated PAH/SPS 9.3/9.3 system was utilized in conjunction with quantum dots (Qdots) to capture and detect a dilute biomarker for prostate cancer, prostate-specific antigen (PSA). Compared to previous work, our system presents a good sensitivity for PSA detection within the clinically relevant range of 0.4-100 ng/mL.
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Affiliation(s)
- Roberta Polak
- †School of Pharmaceutical Sciences, University of Sao Paulo (USP), Sao Paulo, SP, Brazil
| | | | | | - Scott Danielsen
- §Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Marisa M Beppu
- ‡School of Chemical Engineering, University of Campinas (UNICAMP), Campinas, SP, Brazil
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Abstract
Four species of cacti were chosen for this study: Copiapoa cinerea var. haseltoniana, Ferocactus wislizenii, Mammillaria columbiana subsp. yucatanensis and Parodia mammulosa. It has been reported that dew condenses on the spines of C. cinerea and that it does not on the spines of F. wislizenii, and our preliminary observations of M. columbiana and P. mammulosa revealed a potential for collecting dew water. This study found all four cacti to harvest dew on their stems and spines (albeit rarely on the spines of F. wislizenii). Dew harvesting experiments were carried out in the UK, recording an increase in cacti mass on dewy nights. By applying a ranking relative to a polymethyl methacrylate (Plexiglas) reference plate located nearby, it was found that C. cinerea collected the most airborne moisture followed by M. columbiana, P. mammulosa and F. wislizenii respectively, with mean efficiency ratio with respect to the Plexiglas reference of 3.48 ± 0.5, 2.44 ± 0.06, 1.81 ± 0.14 and 1.27 ± 0.49 on observed dewy nights. A maximum yield of normalized performance of 0.72 ± 0.006 l/m(-2) on one dewy night was recorded for C. cinerea. Removing the spines from M. columbiana was found to significantly decrease its dew harvesting efficiency. The spines of three of the species were found to be hydrophilic in nature, while F. wislizenii was hydrophobic; the stems of all four species were hydrophilic. The results of this study could be translated into designing a biomimetic water collecting device that utilizes cactus spines and their microstructures.
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Affiliation(s)
- F T Malik
- The Institute of Life Science, College of Medicine, Swansea University, Swansea, SA2 8PP, UK
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Vander Linden RT, Hemmis CW, Schmitt B, Ndoja A, Whitby FG, Robinson H, Cohen RE, Yao T, Hill CP. Structural basis for the activation and inhibition of the UCH37 deubiquitylase. Mol Cell 2015; 57:901-911. [PMID: 25702872 DOI: 10.1016/j.molcel.2015.01.016] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 12/15/2014] [Accepted: 01/06/2015] [Indexed: 10/24/2022]
Abstract
The UCH37 deubiquitylase functions in two large and very different complexes, the 26S proteasome and the INO80 chromatin remodeler. We have performed biochemical characterization and determined crystal structures of UCH37 in complexes with RPN13 and NFRKB, which mediate its recruitment to the proteasome and INO80, respectively. RPN13 and NFRKB make similar contacts to the UCH37 C-terminal domain but quite different contacts to the catalytic UCH domain. RPN13 can activate UCH37 by disrupting dimerization, although physiologically relevant activation likely results from stabilization of a surface competent for ubiquitin binding and modulation of the active-site crossover loop. In contrast, NFRKB inhibits UCH37 by blocking the ubiquitin-binding site and by disrupting the enzyme active site. These findings reveal remarkable commonality in mechanisms of recruitment, yet very different mechanisms of regulating enzyme activity, and provide a foundation for understanding the roles of UCH37 in the unrelated proteasome and INO80 complexes.
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Affiliation(s)
- Ryan T Vander Linden
- Department of Biochemistry University of Utah School of Medicine, Salt Lake City, UT 84112-5650 USA
| | - Casey W Hemmis
- Department of Biochemistry University of Utah School of Medicine, Salt Lake City, UT 84112-5650 USA
| | - Benjamin Schmitt
- Department of Biochemistry and Molecular Biology Colorado State University, Fort Collins, CO 80523 USA
| | - Ada Ndoja
- Department of Biochemistry and Molecular Biology Colorado State University, Fort Collins, CO 80523 USA
| | - Frank G Whitby
- Department of Biochemistry University of Utah School of Medicine, Salt Lake City, UT 84112-5650 USA
| | - Howard Robinson
- Biology Department Brookhaven National Laboratory, Upton, NY, 11973 USA
| | - Robert E Cohen
- Department of Biochemistry and Molecular Biology Colorado State University, Fort Collins, CO 80523 USA
| | - Tingting Yao
- Department of Biochemistry and Molecular Biology Colorado State University, Fort Collins, CO 80523 USA
| | - Christopher P Hill
- Department of Biochemistry University of Utah School of Medicine, Salt Lake City, UT 84112-5650 USA
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