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Reignier Y, Minc N. Analysis of Cell Wall Mechanics in Fission Yeast. Methods Mol Biol 2025; 2862:77-91. [PMID: 39527194 DOI: 10.1007/978-1-0716-4168-2_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2024]
Abstract
The growth and shape of fungal cells, such as fission yeast, are strongly constrained by the mechanics of their cell wall (CW). The cell wall encases the plasma membrane and defines instantaneous cell shapes by opposing turgor pressure-derived stress on the cell surface. Measuring cell wall mechanical properties may thus bring key insights into the regulation of cell morphogenesis, cell growth, but also cell surface integrity and survival. The fission yeast cell wall has a thickness of a few tens to hundreds of nanometers, and bulk elasticity similar to that of rubber (tens of MPa). These mechanical properties vary locally around single cells, for instance, at the new vs. old growing ends, or birth scars, and may also largely depend on growth conditions and life cycle phases. While cell wall thickness and mechanics have been traditionally measured by complex methodologies including electron microscopy and atomic force microscopy, we here propose a method based on light microscopy to infer with medium-throughput cell wall mechanical properties, as well as turgor pressure in time and space in living cells. This analysis will enhance our appreciation of the mechanical regulation of fission yeast cell morphogenesis and may be directly transferable to the study of other fungal cells.
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Mousavi A, Reniaud J, Santesson M, Persson L, Jansson T. Design of a Phantom Mimicking Rectal Lymph Nodes for Magnetomotive Ultrasound. ULTRASOUND IN MEDICINE & BIOLOGY 2025; 51:77-84. [PMID: 39395868 DOI: 10.1016/j.ultrasmedbio.2024.09.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 08/30/2024] [Accepted: 09/15/2024] [Indexed: 10/14/2024]
Abstract
OBJECTIVE Durable and stable phantoms for verifying and validating the new magnetomotive ultrasound technique are lacking. Here we propose a phantom design to address this need. METHODS A mixture of styrene-butylene/ethylene-styrene (SEBS) in mineral oil and glass beads as a scattering material acted as a bulk material, in which a polyvinyl alcohol (PVA) inclusion containing magnetic nanoparticles in water solution and graphite was embedded. The design mimics nanoparticle-laden lymph nodes embedded in mesorectal fat, as would be the clinical scenario for diagnostic support of staging rectal cancer using magnetomotive ultrasound. RESULTS The estimated reflection between the insert and bulk material was 10%, matching the clinical case of a lymph node within fat (9%). Speed of sound, attenuation, and Young's modulus of the bulk material were matched with those of body fat. The insert also matched the acoustic and elastic properties of lymph node tissue except for attenuation, which was lower than that given in the literature. Glass beads and graphite were used to control backscatter levels in the respective tissue mimics, providing a contrast of -3.8 dB that was consistent with clinical image appearance. The magnitude of magnetomotion remained stable in three separate samples over the course of 3 weeks. CONCLUSION We have developed a phantom for magnetomotive ultrasound that combines the stability of an oil-based bulk material with the necessity of using a water-based material for the insert. The production procedure may be applied to other phantoms where one tissue type needs to be embedded within another.
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Aksakal B, Kaplan Z, Turhan K. The influence of plasticizer on the mechanical, structural, thermal and strain recovery properties following stress-relaxation process of silk fibroin/sodium alginate biocomposites for biomedical applications. J Mech Behav Biomed Mater 2025; 161:106797. [PMID: 39504783 DOI: 10.1016/j.jmbbm.2024.106797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Revised: 10/08/2024] [Accepted: 11/02/2024] [Indexed: 11/08/2024]
Abstract
The influence of plasticizer glycerol (GLY) on the mechanical, structural, and thermal properties of silk fibroin (SF)/sodium alginate (SA) biocomposite films was investigated in detail. As the SF/SA ratio increased up to 65%, the SF content significantly improved the Tensile strength (σT), Young's modulus (Ey) but reduced the elongation at break (εb). To modify and enhance the elasticity and flexibility of the biocomposite films, the GLY as a plasticizer was used at different ratio from 20 to 50% for each SF/SA biocomposite films. Although the extensibility of the films was improved greatly with increasing GLY ratio, σT and Ey reduced significantly. The effect was observed more apparently for the GLY ratio starting from 35%. It was also shown that crystallinity index in the Amide I region increased as the SF/SA ratio increased to 65%. Increasing SF content improved the thermal stability of the SF/SA biocomposites. The XRD results showed that crystallinity was increased as SF/SA ratio increased. Stress-relaxation of SF/SA (30%) biocomposite films plasticized with GLY revealed that each kind of plasticized films showed a viscoelastic behavior and a fast relaxation in the first stage (1-2 min) of the processes and then continued slowly. The GLY increased the extensibility and elasticity limit of the SF/SA (30%) composite films. During the strain recovery processes, the plasticized composite films recovered completely in a quite shorter time than that of unplasticized films. It was observed higher the GLY content, the recovery times became shorter.
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Petersen JC, Campbell LC, Jayne BC, Roberts TJ. Mechanical properties of snake skin vary longitudinally, following large prey ingestion and among species. J Exp Biol 2024; 227:jeb248142. [PMID: 39711310 DOI: 10.1242/jeb.248142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Accepted: 11/07/2024] [Indexed: 12/24/2024]
Abstract
The ability for snakes to ingest large prey (macrostomy) is a widespread, derived trait that involves distending the skin during ingestion and metabolic upregulation during digestion. The material behavior of the skin must accommodate significant stretch associated with a large prey bolus, but data remain sparse for how the material properties of snake skin vary: longitudinally within an individual, after ingesting large prey and among species. To test whether these three factors affected the mechanical properties of snake skin, we quantified uniaxial stresses and strains in circumferential loops of skin from the neck, mid-body and tail of fasted and recently fed Boa constrictor. We also tested skin from several pre-cloacal longitudinal positions in fasted snakes that included two non-macrostomates (Afrotyphlops lineolatus, Anilius scytale) and a highly specialized macrostomate species that eats only bird eggs (Dasypeltis gansi). For B. constrictor, the anterior-most skin failed at higher strains for fed (mean±s.e.m. 2.17±0.10) compared with unfed individuals (1.80±0.04), and maximal stiffness (Young's modulus) had a significant increase posteriorly. The values of Young's modulus for the anterior-most skin of D. gansi (0.050±0.014 MPa) were by far the lowest observed both within that species and among all species. The material properties of skin of the two non-macrostomate species had little longitudinal variation. Hence, the extent of longitudinal variation in skin properties is both species dependent and affected by feeding. The more distensible skin in macrostomates relative to the non-macrostomate species tested suggests that more compliant anterior skin is a derived trait that facilitates macrostomy.
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Molnar SM, Godfrey J, Song B. Balance equations for physics-informed machine learning. Heliyon 2024; 10:e38799. [PMID: 39654737 PMCID: PMC11626790 DOI: 10.1016/j.heliyon.2024.e38799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Revised: 09/30/2024] [Accepted: 09/30/2024] [Indexed: 12/12/2024] Open
Abstract
Using traditional machine learning (ML) methods may produce results that are inconsistent with the laws of physics. In contrast, physics-based models of complex physical, biological, or engineering systems incorporate the laws of physics as constraints on ML methods by introducing loss terms, ensuring that the results are consistent with these laws. However, accurately deriving the nonlinear and high order differential equations to enforce various complex physical laws is non-trivial. There is a lack of comprehensive guidance on the formulation of residual loss terms. To address this challenge, this paper proposes a new framework based on the balance equations, which aims to advance the development of PIML across multiple domains by providing a systematic approach to constructing residual loss terms that maintain the physical integrity of PDE solutions. The proposed balance equation method offers a unified treatment of all the fundamental equations of classical physics used in models of mechanical, electrical, and chemical systems and guides the derivation of differential equations for embedding physical laws in ML models. We show that all of these equations can be derived from a single equation known as the generic balance equation, in conjunction with specific constitutive relations that bind the balance equation to a particular domain. We also provide a few simple worked examples how to use our balance equation method in practice for PIML. Our approach suggests that a single framework can be followed to incorporate physics into ML models. This level of generalization may provide the basis for more efficient methods of developing physics-based ML for complex systems.
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Bhattacharjee T, Petherick R, Harris P, Duncan W. Postmortem interval determination in excised porcine skin using a novel ultrasound-based elasticity measurement device. Int J Legal Med 2024:10.1007/s00414-024-03382-1. [PMID: 39663224 DOI: 10.1007/s00414-024-03382-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2024] [Accepted: 11/19/2024] [Indexed: 12/13/2024]
Abstract
Postmortem interval (PMI) estimation, a parameter critical for solving criminal cases, remains a challenge. It has been suggested that elasticity of decomposing tissue may show a relationship to PMI. We measured elasticity of excised porcine skin at regular intervals for 17 days using a novel ultrasound device. Kruskal-Wallis test followed by Dunn's pair-wise comparison test was performed on the elastic modulus values from each time-point. We found statistically significant differences (p < 0.0001) between the elastic modulus values. Pair-wise comparison showed that tissue measured with a PMI of 1-4, 6-9, 10-14, and 16-17 days can be distinguished from each other based on elastic modulus values. An overall trend of increasing elastic modulus values with time was also observed. Histology and H&E staining of skin samples at PMI of 1, 5, 8, and 12 days showed increasingly prominent fibre bundles which may explain the observed trend. The results of our study suggest that estimation of PMI using an ultrasound device is promising and should be explored further.
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Hariyanto AP, Mugni FF, Khumaira L, Sensusiati AD, Nursela AL, Suprijanto, Ng KH, Haryanto F, Endarko. Fabrication and evaluation of breast tissue equivalent phantoms for image quality assessment in ultrasound imaging. Radiography (Lond) 2024; 31:254-263. [PMID: 39667263 DOI: 10.1016/j.radi.2024.11.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2024] [Revised: 11/23/2024] [Accepted: 11/26/2024] [Indexed: 12/14/2024]
Abstract
INTRODUCTION Phantom materials with tissue-equivalent physical properties that require regular evaluation using patented phantoms are essential for medical device quality assurance programs. This study evaluated phantom materials for tissue equivalence and their use in image quality assessment for breast ultrasound scanner performance testing using two custom-made phantoms. METHODS Two types of phantoms were developed: phantoms A and B. Phantom A was made from a base material consisting of polyvinyl chloride-plastisol with the addition of glycerol, whereas phantom B consisted of polyvinyl chloride-plastisol with the addition of graphite. Each phantom had a stiff and soft lesion shaped like a sphere, with a diameter of 1.4 cm. The phantoms were cuboids with dimensions of 10 × 10 cm2 and a thickness of 5 cm. A series of phantom evaluations was performed, consisting of density, elasticity, acoustic properties, B-mode ultrasound images, and strain ratio. RESULTS The characterisation results show that background A closely resembles fibroglandular tissue in terms of density and acoustic properties (<5% variation); background B only resembles fibroglandular tissue in terms of density (-1.8% variation). In terms of elasticity, both backgrounds were close to the minimum value of fibroglandular tissue elasticity. The soft lesion on the phantom had a slightly lower density and elasticity than the carcinoma, whereas its acoustic properties (speed of sound and attenuation coefficient) were slightly higher than those of the reference carcinoma. Both phantoms were consistent with the literature in terms of strain ratio, geometric accuracy, lesion detection, and mean pixel value and showed good potential stability over one year. CONCLUSION This study successfully described the fabrication and evaluation sequence of a phantom equivalent to breast fibroglandular tissue and its evaluation via ultrasound imaging. IMPLICATIONS FOR PRACTICE This study offers proprietary information essential for the fabrication of phantoms that can be used for quality assurance and control in ultrasound imaging.
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Wu M. Simulating irregular symmetry breaking in gut cross sections using a novel energy-optimization approach in growth- elasticity. J Theor Biol 2024; 595:111971. [PMID: 39448024 DOI: 10.1016/j.jtbi.2024.111971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2024] [Revised: 10/07/2024] [Accepted: 10/14/2024] [Indexed: 10/26/2024]
Abstract
Growth-elasticity (also known as morphoelasticity) is a powerful model framework for understanding complex shape development in soft biological tissues. At each instant, by mapping how continuum building blocks have grown geometrically and how they respond elastically to the push-and-pull from their neighbors, the shape of the growing structure is determined from a state of mechanical equilibrium. As mechanical loads continue to be added to the system through growth, many interesting shapes, such as smooth wavy wrinkles, sharp creases, and deep folds, can form on the tissue surface from a relatively flatter geometry. Previous numerical simulations of growth-elasticity have reproduced many interesting shapes resembling those observed in reality, such as the foldings on mammalian brains and guts. In the case of mammalian guts, it has been shown that wavy wrinkles, deep folds, and sharp creases on the interior organ surface can be simulated even under a simple assumption of isotropic uniform growth in the interior layer of the organ. Interestingly, the simulated patterns are all regular along the tube's circumference, with either all smooth or all sharp indentations, whereas some undulation patterns in reality exhibit irregular patterns and a mixture of sharp creases and smooth indentations along the circumference. Can we simulate irregular indentation patterns without further complicating the growth patterning? In this paper, we have discovered abundant shape solutions with irregular indentation patterns by developing a Rayleigh-Ritz finite-element method (FEM). In contrast to previous Galerkin FEMs, which solve the weak formulation of the mechanical-equilibrium equations, the new method formulates an optimization problem for the discretized energy functional, whose critical points are equivalent to solutions obtained by solving the mechanical-equilibrium equations. This new method is more robust than previous methods. Specifically, it does not require the initial guess to be near a solution to achieve convergence, and it allows control over the direction of numerical iterates across the energy landscape. This approach enables the capture of more solutions that cannot be easily reached by previous methods. In addition to the previously found regular smooth and non-smooth configurations, we have identified a new transitional irregular smooth shape, new shapes with a mixture of smooth and non-smooth surface indentations, and a variety of irregular patterns with different numbers of creases. Our numerical results demonstrate that growth-elasticity modeling can match more shape patterns observed in reality than previously thought.
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Soni A. Estimating price elasticities of demand for pain relief drugs: evidence from Medicare Part D. INTERNATIONAL JOURNAL OF HEALTH ECONOMICS AND MANAGEMENT 2024; 24:481-515. [PMID: 39093341 DOI: 10.1007/s10754-024-09382-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Accepted: 07/21/2024] [Indexed: 08/04/2024]
Abstract
Overdose deaths from prescription opioids remain elevated, and policymakers seek solutions to curb opioid misuse. Recent proposals call for price-based solutions, such as opioid taxes and removal of opioids from insurance formularies. However, there is limited evidence on how opioid consumption responds to price stimuli. This study addresses that gap by estimating the effects of prices on the utilization of opioids, as well as other prescription painkillers. I use nationally representative individual-level data on prescription drug purchases and exploit the introduction of Medicare Part D in 2006 as an exogenous change in out-of-pocket drug prices. I find that new users have a relatively high price elasticity of demand for prescription opioids, and that consumers treat over-the-counter painkillers as substitutes for prescription painkillers. My results suggest that increasing out-of-pocket prices of opioids, through formulary design or taxes, may be effective in reducing new opioid use.
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Liu C, Li Z, Liu L, Qu X, Shi Z, Ma Z, Wang X, Huang F. A thermal cross-linking approach to developing a reinforced elastic chitosan cryogel for hemostatic management of heavy bleeding. Carbohydr Polym 2024; 345:122599. [PMID: 39227116 DOI: 10.1016/j.carbpol.2024.122599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2024] [Accepted: 08/07/2024] [Indexed: 09/05/2024]
Abstract
Uncontrolled hemorrhage stands as the primary cause of potentially preventable deaths following traumatic injuries in both civilian and military populations. Addressing this critical medical need requires the development of a hemostatic material with rapid hemostatic performance and biosafety. This work describes the engineering of a chitosan-based cryogel construct using thermo-assisted cross-linking with α-ketoglutaric acid after freeze-drying. The resulting cryogel exhibited a highly interconnected macro-porous structure with low thermal conductivity, exceptional mechanical properties, and great fluid absorption capacity. Notably, assessments using rabbit whole blood in vitro, as well as rat liver volume defect and femoral artery injury models simulating severe bleeding, showed the remarkable hemostatic performance of the chitosan cryogel. Among the cryogel variants with different chitosan molecular weights, the 150 kDa one demonstrated superior hemostatic efficacy, reducing blood loss and hemostasis time by approximately 73 % and 63 % in the hepatic model, and by around 60 % and 68 %, in the femoral artery model. Additionally, comprehensive in vitro and in vivo evaluations underscored the good biocompatibility of the chitosan cryogel. Taken together, these results strongly indicate that the designed chitosan cryogel configuration holds significant potential as a safe and rapid hemostatic material for managing severe hemorrhage.
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Skinner J, Langley N, Fahrenholtz S, Shanavas Y, Waletzki B, Brown R, Herrick J, Shyamsunder L, Goguen P, Rajan S. Microscopic characteristics of peri- and postmortem fracture surfaces. Forensic Sci Int 2024; 365:112223. [PMID: 39437525 DOI: 10.1016/j.forsciint.2024.112223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2024] [Revised: 08/07/2024] [Accepted: 09/09/2024] [Indexed: 10/25/2024]
Abstract
This study investigated if microscopic surface features captured with a scanning electron microscope (SEM) effectively discriminate fracture timing. We hypothesized that microscopic fracture characteristics, including delamination, osteon pullout, and microcracks, may vary as bone elasticity decreases, elucidating perimortem and postmortem events more reliably than macroscopic analyses. Thirty-seven unembalmed, defleshed human femoral shafts from males (n=18) and females (n=2) aged 33-81 years were fractured at experimentally simulated postmortem intervals (PMIs) ranging from 1 to 60 warm weather days (250-40,600 ADH). A gravity convection oven was used to approximate tissue decomposition at 37 C and 27 C, and the resulting heat-time unit (accumulated degree hours, or ADH) was used to examine fractures in elastic/wet versus brittle/dry bone. The bones were fractured with a drop test frame using a three-point bending setup, sensors were used to calculate fracture energy, and high-speed photography documented fracture events. The following data were collected to relate fracture appearance to the biomechanical properties of bone: PMI (postmortem interval) length in ADH, temperature, humidity, collagen percentage, water loss, bone mineral density, cortical bone thickness, fracture energy, age, sex, cause of death, and microscopic fracture feature scores. SEM micrographs were collected from the primary tension zones of each fracture surface, and three microscopic fracture characteristics were scored from a region of interest in the center of the tension zone: percentage of delaminated osteons, percent osteon pullout, and number of microcracks. Multiple linear regression showed that microscopic fracture surface features are strong predictors of ADH (adjusted R-squared=0.67 for the 0 - 40,000 ADH samples; adjusted R-squared=0.92 for the 0-16,000 ADH samples). Osteon pullout is the single best predictor of ADH. Additionally, water loss is the primary driver of bone elasticity changes in low ADH samples, while collagen fibers appear to remain intact until later in the postmortem interval (approximately 40,000 ADH in this study). The results of this study indicate microscopic fracture surface analysis detects the biomechanical effects of decreased elasticity more reliably and with greater sensitivity than macroscopic analysis.
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Ulker Z, Bozbay R, Buyuk SD, Orakdogen N. Eco-friendly property modulation of biobased gels of carboxymethyl cellulose-integrated poly(tertiary amine)s for the removal of azo-food dyes. Int J Biol Macromol 2024; 282:137199. [PMID: 39489245 DOI: 10.1016/j.ijbiomac.2024.137199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2024] [Revised: 10/08/2024] [Accepted: 10/31/2024] [Indexed: 11/05/2024]
Abstract
Anionic polysaccharide-based gels enable the design of biobased materials with biochemical properties, non-toxic and natural origin. A new set of cationic gels was prepared from carboxymethylcellulose (CMC)-doped tertiary amino functional cationic monomers 2-(dimethylamino)ethyl methacrylate and N-(3-(dimethylamino)propyl) methacrylamide via the formation of semi-interpenetrated network (semi-IPN) at different polymerization temperatures, Tprep. A detailed understanding of the temperature-dependent synthesis and physicochemical response is required for the design of interpenetrating networks with CMC as an adsorbent that provides effective sources for the removal of azo-food dyes such as tartrazine and carmoisine from aqueous solutions. The variation of elasticity and swelling properties with respect to polymerization temperature was investigated. CMC-integration and polymerization temperature played a decisive role in the compressive elasticity. Incorporation of CMC into copolymer matrix led to a significant increase in elasticity of semi-IPNs, while mechanically weaker gels were obtained with increasing Tprep. Addition of CMC increased the swelling modulus of semi-IPNs formed at -18 °C by 2.6-fold. While the transparency changed depending on Tprep and microstructure, addition of CMC decreased the swelling rate of gels at all polymerization temperatures. The compressive modulus decreased with the swelling process in accordance with the Rubber elasticity theory. Semi-IPN gels showed stable swelling against pH-change in aqueous solutions and exhibited excellent pH-sensitivity significantly in low pH. A 4 to 12 fold decrease in maximum volume was observed by varying the pH between 2.1 and 9.8. The correlation between polymerization temperature and removal of azo-food dyes; tartrazine and carmoisine from contaminated wastewater with CMC-based gels was studied. Dynamic adsorption equilibrium was reached in 30 min, and tartrazine and carmoisine removal performances varied between 92.8 % and 98.4 %. respectively. The adsorption data for azo-dyes were evaluated by Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Redlich-Patterson, Sips, and Tooth isotherm models, but were best described by Langmuir and Redlich-Patterson models as they gave the highest correlation. Pseudo-first order, pseudo-second order, Elovich, Avrami kinetic and intra-particle diffusion models were investigated and dye adsorption was represented by pseudo-second-order model. After the adsorption process, semi-IPNs can easily be regenerated and effectively reused over five cycles. The study provided new insights towards the facile and sustainable synthesis of eco-friendly multifunctional CMC-based gels carrying tertiary amino groups for effective removal of azo-based food colorants.
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Chen H, Wang Y, Huang Z, Xiao T, Guo T, Wang Y, Wu C, Ren Z. Elastic and recoverable sponges based on collagen/yeast β-glucan for quick hemostasis. Int J Biol Macromol 2024; 282:137095. [PMID: 39486727 DOI: 10.1016/j.ijbiomac.2024.137095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2024] [Revised: 10/27/2024] [Accepted: 10/29/2024] [Indexed: 11/04/2024]
Abstract
In this investigation, we aimed to engineer sponges with exceptional mechanical and hemostatic capabilities for effective wound healing. By combining collagen, a stiff fibril protein in ECM, with β-glucan, an elastic and triple-helical polysaccharide from yeast cell wall, we prepared a series of composite sponges, designated as CY sponges. This material exhibited a uniform pore structure, displaying enhanced elasticity and shape recovery ability compared to pure collagen sponges. Also, the incorporation of Yeast β-glucan (YG) significantly improved the fluid absorption ability and stability of the sponges. In vitro hemostasis tests demonstrated that the CY sponges exhibited a notably lower in vitro coagulation index (19.21 %) compared to the collagen control (64.84 %), accompanied by superior erythrocyte (64.64 %) and platelet (64.95 %) adhesion properties. Animal studies further substantiated the sponge's hemostatic efficacy, as CY40 led to a reduction in average bleeding volume by 25.26 % and 28.97 %, and a shorter hemostatic time by 31.70 % and 30.77 % compared to collagen, indicating accelerated wound healing. These findings suggest that the addition of yeast β-glucan into collagen sponges can improve their elasticity, shape recovery ability, hemostatic performance and wound repair ability.
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Ma X, Kong S, Li Z, Zhen S, Sun F, Yang N. Effect of cross-linking density on the rheological behavior of ultra-soft chitosan microgels at the oil-water interface. J Colloid Interface Sci 2024; 672:574-588. [PMID: 38852358 DOI: 10.1016/j.jcis.2024.06.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 06/02/2024] [Accepted: 06/03/2024] [Indexed: 06/11/2024]
Abstract
In this paper, microgels with uniform particle size were prepared by physically cross-linking the hydrophobically modified chitosan (h-CS) with sodium phytate (SP). The effects of cross-linking density on the interfacial adsorption kinetics, viscoelasticity, stress relaxation, and micorheological properties of the hydrophobically modified chitosan microgels (h-CSMs) at the oil-water interface were extensively investigated by the dilatational rheology, compressional rheology, and particle tracing microrheology. The results were correlated with the particle size, morphology, and elasticity of the microgels characterized by dynamic light scattering and atomic force microscopy. It was found that with the increase of cross-linking density, the h-CSMs changed from a polymer-like state to ultra-soft fussy spheres with higher elastic modulus. The compression isotherms demonstrated multi-stage increase caused by the interaction between the shells and that between the cores of the microgels successively. As the increase of cross-linking density, the h-CSMs diffused slower to the oil-water interface, but demonstrating faster permeation adsorption and rearrangement at the oil-water interface, finally forming interfacial layers of higher viscoelastic modulus due to the core-core interaction. Both the initial tension relaxation and the microgel rearrangement after interface expansion became faster as the microgel elasticity increased. The interfacial microrheology demonstrated dynamic caging effect caused by neighboring microgels. This article provides a more comprehensive understanding of the behaviors of polysaccharide microgels at the oil-water interface.
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Khair RM, Sukanen M, Finni T. Achilles Tendon Stiffness: Influence of Measurement Methodology. ULTRASOUND IN MEDICINE & BIOLOGY 2024; 50:1522-1529. [PMID: 39079832 DOI: 10.1016/j.ultrasmedbio.2024.06.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 05/15/2024] [Accepted: 06/16/2024] [Indexed: 09/06/2024]
Abstract
OBJECTIVE Mechanical stiffness derived from force-elongation curves is fundamentally different from shear wave (SW) elastography-based tissue properties. We compared these techniques, with a total of five methods of assessing Achilles tendon (AT) stiffness. METHODS Seventeen participants (12 male and 5 female) with unilateral AT rupture performed submaximal contractions at 30% and 10% maximal isometric contraction torque of the un-injured limb. SW velocity was acquired at rest. Force-elongation curves were assessed from the free AT and the medial gastrocnemius (MG) tendon. Mechanical stiffness was determined near the end of the linear region of the force-elongation curve and from the toe region. Bivariate correlations between mechanical stiffness and SW velocity, as well as pairwise t-tests between limbs, were computed. RESULTS In the injured limb, SW velocity correlated with MG tendon and free AT toe-region stiffness during 10% (r = 0.59, p = 0.020 and r = 0.60, p = 0.011, respectively) and 30% of submaximal contractions (r = 0.56, p = 0.018 and r = 0.67, p = 0.004, respectively). The un-injured limb showed no associations. In both limbs pooled together, SW velocity correlated with MG tendon toe-region stiffness in 30% of submaximal contractions (r = 0.43, p = 0.012). Free tendon mechanical stiffness was lower in the injured limb, with a mean difference of 148.5 Nmm⁻¹ (95% CI: 35.6-261.3, p = 0.013), while SW velocity was higher in the injured limb (1.67 m × s⁻¹, 95% CI; -2.4 to -0.9, p < 0.001). CONCLUSION SW elastography may reflect AT viscoelastic properties at the initial slope of the force-length curve with strains <1% but cannot offer insight into AT mechanics at higher loads. Extended toe regions in the injured limb could have caused the association between mechanical stiffness and SW-based stiffness.
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Jia B, Dong Z, Ren X, Niu M, Kong S, Wan X, Huang H. Hydrogels composite optimized for low resistance and loading-unloading hysteresis for flexible biosensors. J Colloid Interface Sci 2024; 671:516-528. [PMID: 38815387 DOI: 10.1016/j.jcis.2024.05.142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 05/09/2024] [Accepted: 05/19/2024] [Indexed: 06/01/2024]
Abstract
With the advancement of wearable and implantable medical devices, hydrogel flexible bioelectronic devices have attracted significant interest due to exhibiting tissue-like mechanical compliance, biocompatibility, and low electrical resistance. In this study, the development and comprehensive performance evaluation of poly(acrylic acid)/ N,N'-bis(acryloyl) cystamine/ 1-butyl-3-ethenylimidazol-1-ium:bromide (PAA/NB/IL) hydrogels designed for flexible sensor applications are introduced. Engineered through a combination of physical and chemical cross-linking strategies, these hydrogels exhibit strong mechanical properties, high biocompatibility, and effective sensing capabilities. At 95 % strain, the compressive modulus of PAA/NB/IL 100 reach up to 3.66 MPa, with the loading-unloading process showing no significant hysteresis loop, indicating strong mechanical stability and elasticity. An increase in the IL content was observed to enlarge the porosity of the hydrogels, thereby influencing their swelling behavior and sensing functionality. Biocompatibility assessments revealed that the hemolysis rate was below 5 %, ensuring their suitability for biomedical applications. Upon implantation in rats, a minimal acute inflammatory response was observed, comparable to that of the biocompatibility control poly(ethylene glycol) diacrylate (PEGDA). These results suggest that PAA/NB/IL hydrogels hold promise as biomaterials for biosensors, offering a balance of mechanical integrity, physiological compatibility, and sensing sensitivity, thereby facilitating advanced healthcare monitoring solutions.
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Li J, Yuan H, Gao Y. Influencing Factors, Reference Range and Repeatability of Salivary Gland Ultrasound Viscoelastic Imaging in Healthy Adults. ULTRASOUND IN MEDICINE & BIOLOGY 2024; 50:1544-1550. [PMID: 39030091 DOI: 10.1016/j.ultrasmedbio.2024.06.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 05/27/2024] [Accepted: 06/18/2024] [Indexed: 07/21/2024]
Abstract
OBJECTIVE The study aimed to determine the influencing factors, reference range, the changes of salivary gland secretion function and repeatability of measurements taken from ultrasound (US) viscoelastic imaging in the salivary glands of healthy adults. METHODS From August 2023 to October 2023, 206 healthy adults were recruited. In November 2023, 50 healthy adults were recruited for acid stimulation testing. All volunteers underwent conventional and viscoelastic US of the salivary glands. The viscoelasticity values in different regions of interest (ROI), observers, genders, ages, body mass index (BMI) groups and before and after acid stimulation were compared separately. A two-sided 95% reference range was estimated accordingly. RESULTS There was no difference in the E-mean and V-mean values among different ROIs (p > 0.05). The intra-group correlation coefficient values between the different observers were all >0.908. Except for the influence of age on the E-mean value of the parotid gland, the V-mean of the parotid gland, the E-mean and V-mean of the submandibular gland were not affected by age, gender or BMI. Finally, differences were detected in the E-means and V-means of the parotid and submandibular glands before and after acid stimulation (p < 0.05). CONCLUSION US viscoelastic imaging is a simple and reliable technique for evaluating the stiffness and viscosity of salivary glands in healthy adults. It also can be used to dynamically evaluate the changes of salivary gland secretion function.
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Tian J, Wang Z, Xiao Y. The difference of dynamic elasticity characteristics and stroke effect between two types of new material seamed plastic table tennis ball. Sci Rep 2024; 14:22698. [PMID: 39349959 PMCID: PMC11442490 DOI: 10.1038/s41598-024-73829-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Accepted: 09/20/2024] [Indexed: 10/04/2024] Open
Abstract
The diameter and weight of different brands of table tennis ball will affect the ball's elasticity and stroke. The purpose of this study is to analyze the difference of the dynamic elasticity and stroke effect between the two brands of new plastic ball. A self-made experiment was designed to test the dynamic elasticity characteristics of DHS D40 + and Nittaku 40+. Table tennis players (N = 18) were randomly selected from the China Table Tennis College (Mage = 15.16 ± 2.41; Mheight = 1.59 ± 0.32 m; Mweight = 45.72 ± 5.17 kg). Each participant was righthand shake-hands grip. A speedometer was used to record the ball speed and a high-speed camera was used to measure the spin speed. Data normality was verified by using the Kolmogorov-Smirnov test. The independent t-test was conducted to assess the differences of the dynamic elasticity and stroke effect between the two types of plastic ball. Results showed that the rebound speed and decrement rate of DHS D40 + and Nittaku 40 + both increased with the increased falling speed, respectively. When falling at high speed, there was a significant difference of dynamic elasticity between DHS D40 + and Nittaku 40+ (p < 0.01). There was also a significant difference in the ball speed and spin speed between the two types of new material seamed plastic ball during the backhand backspin stroke (p = 0.041, p = 0.022, respectively), and the ball speed and spin speed of DHS D40 + were higher than that of Nittaku 40 + ball. Compared with the DHS D40+, the Nittaku 40 + has a faster rebound speed, higher rebound height, and better dynamic elasticity. Therefore, under same striking conditions, when hitting the Nittaku 40 + ball, players need to increase the swing distance and hit the ball with more strength to improve the ball speed and rotation speed; increase the spin and decrease the ball's rebound height of the serve.
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Jia W, Xia S, Jia X, Tang B, Cheng S, Nie M, Guan L, Duan Y, Zhang M, Chen X, Zhang H, Bai B, Jia H, Li N, Yuan C, Cai E, Dong Y, Zhang J, Jia Y, Liu J, Tang Z, Luo T, Zhang X, Zhan W, Zhu Y, Zhou J. Ultrasound Viscosity Imaging in Breast Lesions: A Multicenter Prospective Study. Acad Radiol 2024; 31:3499-3510. [PMID: 38582684 DOI: 10.1016/j.acra.2024.03.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 02/16/2024] [Accepted: 03/17/2024] [Indexed: 04/08/2024]
Abstract
RATIONALE AND OBJECTIVES To explore and validate the clinical value of ultrasound (US) viscosity imaging in differentiating breast lesions by combining with BI-RADS, and then comparing the diagnostic performances with BI-RADS alone. MATERIALS AND METHODS This multicenter, prospective study enrolled participants with breast lesions from June 2021 to November 2022. A development cohort (DC) and validation cohort (VC) were established. Using histological results as reference standard, the viscosity-related parameter with the highest area under the receiver operating curve (AUC) was selected as the optimal one. Then the original BI-RADS would upgrade or not based on the value of this parameter. Finally, the results were validated in the VC and total cohorts. In the DC, VC and total cohorts, all breast lesions were divided into the large lesion, small lesion and overall groups respectively. RESULTS A total of 639 participants (mean age, 46 years ± 14) with 639 breast lesions (372 benign and 267 malignant lesions) were finally enrolled in this study including 392 participants in the DC and 247 in the VC. In the DC, the optimal viscosity-related parameter in differentiating breast lesions was calculated to be A'-S2-Vmax, with the AUC of 0.88 (95% CI: 0.84, 0.91). Using > 9.97 Pa.s as the cutoff value, the BI-RADS was then modified. The AUC of modified BI-RADS significantly increased from 0.85 (95% CI: 0.81, 0.88) to 0.91 (95% CI: 0.87, 0.93), 0.85 (95% CI: 0.80, 0.89) to 0.90 (95% CI: 0.85, 0.93) and 0.85 (95% CI: 0.82, 0.87) to 0.90 (95% CI: 0.88, 0.92) in the DC, VC and total cohorts respectively (P < .05 for all). CONCLUSION The quantitative viscous parameters evaluated by US viscosity imaging contribute to breast cancer diagnosis when combined with BI-RADS.
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Ando R. Association of the rate of torque development and joint angle with passive muscle stiffness. Eur J Appl Physiol 2024; 124:2665-2673. [PMID: 38630263 DOI: 10.1007/s00421-024-05483-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 04/03/2024] [Indexed: 09/02/2024]
Abstract
PURPOSE The purpose of this study was to statistically compare the rate of torque development normalized by maximal strength (relative RTD) across ankle angles. Additionally, this study was aimed at exploring the correlation coefficients between relative RTD and passive stiffness of the medial gastrocnemius (MG) at different ankle angles. METHODS Twenty-two healthy men and women (age: 31 ± 4 years) performed randomly-ordered explosive isometric plantar flexions at plantarflexed (15°), neutral (0°), and dorsiflexed (- 15°) angles; relative RTD comprised the slope of the time-torque curve normalized to maximal torque. The shear wave velocity (SWV; index of stiffness) of the MG at rest was measured at each angle using ultrasound shear wave elastography. RESULTS The relative RTD was greater at 15° than - 15° for 0-50, 0-100, and 0-150 ms time-windows and at 15° than 0° for the 0-150 ms time-window (P < 0.05), although peak torque was lower at 15° than 0° and - 15° (P < 0.05). The relative RTD for the 0-50 ms time-window correlated with SWV at - 15° (rs = 0.475, P < 0.05), but not at 15º and 0º. Furthermore, the correlation coefficient of RTD for the 0-100 ms time-window with SWV was significantly greater at - 15° (rs = 0.420) than 0 ° (rs = - 0.109). CONCLUSIONS A greater relative RTD occurs at plantarflexed angles (i.e., the ascending limb of the force-length curve) in the triceps surae, and relative RTD is strongly related to passive MG stiffness at dorsiflexed angles (i.e., longer muscle lengths).
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Douglas KA, Drakonaki EE, Douglas VP, Detorakis ET. Shear-wave elastographic imaging in choroidal melanomas: clinical and hemodynamic correlations. Jpn J Ophthalmol 2024; 68:523-530. [PMID: 39088115 DOI: 10.1007/s10384-024-01086-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 05/29/2024] [Indexed: 08/02/2024]
Abstract
PURPOSE This study evaluated the role of shear wave elastography imaging (SWEΙ) in uveal melanomas and the associations between SWEI and clinical and hemodynamic findings. STUDY DESIGN Prospective, clinical study METHODS: Twelve patients with uveal melanomas, scheduled to undergo Ru-106 brachytherapy, were prospectively recruited from the Department of Ophthalmology of the University Hospital of Heraklion (September-December 2022). B-mode, hemodynamic and SWEI ultrasonography examinations were performed with the HiScan (OPTIKON 2000) and the LOGIQ E9 (GE Healthcare) sonographic systems, respectively. Differences in SWEI scores (kPa) between tumor (TS) and adjacent non-affected choroid (CS), as well as between TS and orbital fat (FS) were examined. Correlations between SWEI and intra-tumoral hemodynamic parameters, including peak systolic and end diastolic velocities and resistivity index (RI) were also examined. RESULTS TS was significantly correlated with intra-tumoral RI (Pearson's bivariate correlation coefficient 0.681, p=0.015) and with maximal tumor height (Pearson's bivariate correlation coefficient 0.620, p=0.031). TS was significantly higher than both FS and CS scores (paired-samples t-test, p=0.003 and p=0.006, respectively). CONCLUSIONS SWEI score is applicable as a quantitative biomechanical marker in the assessment of choroidal melanoma. Choroidal melanomas are stiffer than both adjacent choroid and orbital fat. Moreover, choroidal melanomas with higher RI as well as those with higher apical elevations display higher SWEI scores.
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Maceo Heilman B, Mote K, Batchelor W, Rowaan C, Gonzalez A, Arrieta E, Ruggeri M, Ziebarth N, Cabrera-Ghayouri S, Dibas M, Parel JM, Manns F. Effect of compound treatments on mouse lens visco elasticity. Exp Eye Res 2024; 246:109992. [PMID: 38972445 DOI: 10.1016/j.exer.2024.109992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 06/18/2024] [Accepted: 07/04/2024] [Indexed: 07/09/2024]
Abstract
Previous studies have shown that pharmaceutical agents such as lipoic acid have the ability to soften the lens, presenting a promising avenue for treating presbyopia. One obstacle encountered in the preclinical stage of such agents is the need for precise measurements of lens elasticity in experimental models. This study aimed to evaluate the effects of 25-hydroxycholesterol, lipoic acid, and obeticholic acid on the viscoelastic properties of mouse lenses using a custom-built elastometer system. Data were acquired on lenses from C57BL/6J female mice from two age groups: young (age: 8-10 weeks) and old (age: 32-43 weeks). OD lenses were used as the control and OS lenses were treated. Control lenses were immersed in Dulbecco's Modified Eagle Medium (DMEM) and treatment lenses were immersed in a compound solution containing 25-hydroxycholesterol (5 young and 5 old), lipoic acid at 2.35 mM (5 young and 5 old), lipoic acid at 0.66 mM (5 old), or obeticholic acid (5 old) at 37 °C for 18 h. After treatment, the mouse lenses were placed in a DMEM-filled chamber within a custom-built elastometer system that recorded the load and lens shape as the lens was compressed by 600 μm at a speed of 50 μm/s. The load was continuously recorded during compression and during stress-relaxation. The compression phase was fit with a linear function to quantify lens stiffness. The stress-relaxation phase was fit with a 3-term exponential relaxation model providing relaxation time constants (t1, t2, t3), and equilibrium load. The lens stiffness, time constants and equilibrium load were compared for the control and treated groups. Results revealed an increase in stiffness with age for the control group (young: 1.16 ± 0.11 g/mm, old: 1.29 ± 0.14 g/mm) and relaxation time constants decreased with age (young: t1 = 221.9 ± 29.0 s, t2 = 24.7 ± 3.8 s, t3 = 3.12 ± 0.87 s, old: t1 = 183.0 ± 22.0 s, t2 = 20.6 ± 2.6 s and t3 = 2.24 ± 0.43 s). Among the compounds tested, only 25-hydroxycholesterol produced statistically significant changes in the lens stiffness, relaxation time constants, and equilibrium load. In conclusion, older mouse lenses are stiffer and less viscous than young mouse lenses. Notably, no significant change in lens stiffness was observed following treatment with lipoic acid, contrary to previous findings.
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Shurrab AM, Shatarat AT, Al-Muhtaseb MH, Badran DH, Salameh MA, Al-Lahham HM, Altaweel RK, Altarawneh I, Al-Qattan D. The effect of irisin on the ultrastructure of the thoracic aorta in rat: A morphometric study. Morphologie 2024; 108:100779. [PMID: 38608628 DOI: 10.1016/j.morpho.2024.100779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Revised: 03/14/2024] [Accepted: 03/27/2024] [Indexed: 04/14/2024]
Abstract
BACKGROUND One of the most recent hormones to be identified and isolated is irisin, extracted from mouse skeletal muscle in 2012. Irisin has been proven to alter blood pressure, which has an impact on blood vessels, enhance endothelial functions, and prevent injury to endothelial cells. The current study aimed to study the effect of irisin on the ultrastructure of the rat thoracic aorta using the transmission electron microscope (TEM). MATERIALS AND METHODS Twenty female rats were recruited for this study and divided into a control group (non-injected), and four experimental groups (injected groups) each consisting of 4 rats. The experimental groups were injected intraperitoneally with different doses of irisin (250ng/mL, 500ng/mL, 1000ng/mL, and 2000ng/mL) twice a week for 4weeks. Then, the descending thoracic aorta of all experimental rats were resected and proceeded with imaging. RESULTS The results of this study showed a change in the thickness of the tunica intima, internal elastic lamina, elastic lamellae, and external elastic lamina concerning increasing injected irisin concentration. While there was a significant increase in the thickness of tunica media (P<0.0001) and smooth muscle cells (P<0.05). Also, the results showed a significant increase in the number of elastic lamellae in the tunica media (P<0.0001). CONCLUSION Irisin had a major impact on the elasticity of the rat thoracic aorta wall, suggesting that it influences the growth factors of the wall and activates smooth muscle cells in addition to endothelial cells.
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Assari AH, Shaghaghi N, Yaghoobi S, Ghaderi S. Determining the characteristics of representative volume elements in severely deformed aluminum-matrix composite. Heliyon 2024; 10:e36489. [PMID: 39253143 PMCID: PMC11381769 DOI: 10.1016/j.heliyon.2024.e36489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Revised: 08/14/2024] [Accepted: 08/16/2024] [Indexed: 09/11/2024] Open
Abstract
The accurate evaluation of the effective mechanical properties of composites mainly depends on the characteristics of representative volume elements (RVEs). This paper mainly investigates the RVE size. Additionally, the effect of volume fraction of reinforcement, the edge effect, and RVE types on the critical size are discussed. First, the Al/Ni multilayered composites were processed by nine cycles of the cross-accumulative roll bonding (CARB) method. Then, one type of RVEs was created based on cross-sectional micrographs of composites to consider their inhomogeneities. Another type was generated by using the random sequential adsorption (RSA) procedure. Thereafter, the homogenized effective elastic properties of both types of microstructure-based RVEs and RSA-based RVEs were computed and compared as a function of the volume fraction of Ni and RVE size. The results showed that by increasing the Ni fragments, the RVEs indicated stiffer elastic behavior. By increasing the volume fraction of Ni from 0.2 Vf to 0.8 Vf, the Poisson ratio decreased by 7 % and the elastic modulus increased by 83 % for RSA-based RVE. Regarding the size of microstructure-based RVE of Al/Ni (0.8 Vf), from the largest size (size 1) with a length of 575 μm and a width of 575 μm to the smallest size (size 5) with a length of 287.5 μm and a width of 287.5 μm, the elastic modulus and the Poisson ratio showed 16 % and 0.8 % decrease, respectively.
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de Oliveira Abrahão J, Hermont Cançado R, de Campos França E, de Arruda Santos L, Damas Resende P, Weidenbach Degrazia F, Santos Neves L. Influence of distal-end heat treatment in the properties of heat-activated NiTi archwires. J Orofac Orthop 2024:10.1007/s00056-024-00547-w. [PMID: 39190140 DOI: 10.1007/s00056-024-00547-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 07/07/2024] [Indexed: 08/28/2024]
Abstract
PURPOSE The aim of this study was to evaluate the extent of property changes caused by heating the distal portion of heat-activated nickel-titanium (NiTi) wires. METHODS Forty preformed heat-activated NiTi archwires (3M Unitek, Monrovia, CA, USA) with a nominal cross-section of 0.018″ were used in this study. The archwires were divided into a control group, not submitted to heat treatment and, thus, maintaining the as-received properties, and an experimental group, in which the archwires were submitted to heat treatment for distal bending at one end. Wire segments of control and experimental groups were submitted to differential scanning calorimetry (DSC) and Vickers microhardness measurements. RESULTS The DSC results suggest local recrystallization and precipitate dissolution at the heat-treated tip, which decreases as the distance to the wire's tip increases. Vickers microhardness tests revealed significant changes for distances between 6 and 8 mm from the wire's tip. Heating the distal portion of heat-activated NiTi archwires should be performed with care since this clinical procedure may compromise the performance of these wires to a distance of 8 mm from the archwire end. CONCLUSION Heat treatment for distal bending in heat-activated NiTi archwires may be performed, with little impact on the areas adjacent to heat treatment. In cases presenting molars requiring significant orthodontic corrections, it should be preferred to apply other techniques to avoid archwire sliding, such as crimpable stops, or to have flame control to avoid placing a heat-treated section in the tubes of these molars.
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