Number Of Fibers Research Articles

Dedifferentiation- and aging-induced loss of mechanical contractility and polarity in vascular smooth muscle cells: Heterogeneous changes in macroscopic and microscopic behavior of cells in serial passage culture

Dedifferentiation and aging of vascular smooth muscle cells (VSMCs) are associated with serious vascular diseases, such as arteriosclerosis and aneurysm. However, how cell dedifferentiation and aging affect cellular mechanical behaviors at the single-cell and intracellular structure levels remains unclear. An in-depth understanding of these interactions is extremely important for understanding the mechanism underlying VSMC mechanical integrity and homeostatic regulation of vascular walls. Herein, we systematically investigated changes in VSMC morphology, structure, contractility, and motility during dedifferentiation and aging induced by serial passage culture using traction force microscopy with elastic micropillar substrates, laser nanodissection of cytoskeletons, confocal fluorescence microscopy, and atomic force microscopy. We found that VSMC dedifferentiation started in the middle stage of serial passage culture, accompanied by a transient cell spreading in the cell width and decrease in contractile protein expression. Dedifferentiated VSMCs showed a significant decrease in the contraction and stiffness of individual actin stress fibers; however, their overall cell traction forces were maintained. Simultaneously, a significant increase in cell motility and the number of actin fibers was observed in dedifferentiated VSMCs, which may be associated with the enhancement of cell migration and disruption of cell/tissue integrity during the early stage of vascular diseases. As cell senescence progressed in the later stage of serial passage culture, VSMCs displayed reduced cell spreading and migration with decrease in the overall cell traction forces and drastic reduction in mechanical polarity of cell structures and forces. These results suggested that cell senescence causes loss of mechanical contractility and polarity in VSMCs, which may be an important factor in vascular disease progression. The experimental systems established in this study can be powerful tools for understanding the mechanisms underlying cellular dedifferentiation and aging from a biomechanical perspective.

280 AntagomiR-22-3p Injection alters miRNA expression and muscle fiber type of intrauterine growth restricted lambs

Abstract microRNAs (miRNA) are small non-coding RNAs that modulate muscle satellite cell proliferation. Previous research identified miR-22-3p as differentially expressed during ovine muscle development and in vitro experiments showed that antagomir-22-3p treatment enhanced satellite cell proliferation. The objective of this study was to test in vivo vascular injection of antagomir-22-3p in lateral saphenous vein on miRNA and HDAC family mRNA expression in intrauterine growth restricted lambs. Pregnant ewes (n = 18) with twins were either fed at 100% of NRC (CON) or nutrient restricted (60% NRC; NR) from gestational d 85 to parturition. On d 12 of age, NR lambs (n = 8) were randomly selected and given a systemic injection of antagomir-22-3p in the lateral saphenous vein of the right leg (MIR-NR). CON lambs (n = 8) were also randomly selected and given a sham injection of PBS in the lateral saphenous vein of the right leg (SHAM-CON). Antagomir-22-3p was reconstituted in phosphate buffered saline (PBS). Injections were given for 3 consecutive days and lambs harvested 24 d later. Blood samples were collected from each lamb weekly to monitor miR-22-3p expression. Lambs were slaughtered 24 d after the first injection and muscle mass measured. Muscle samples were removed for miR-22-3p and mRNA expression of potential targets. Cell-free circulating RNA was isolated from blood samples and miR-22-3p expression examined over time. Cell-free circulating miR-22-3p expression was downregulated (P < 0.05) for MIR-NR compared with SHAM-CON on d 14 after injection. On d 21 after injection, miR-22-3p expression in plasma tended (P = 0.08) to be down-regulated in MIR-NR compared with SHAM-CON. Lamb body weight and muscle weights at harvest were similar between MIR-NR and SHAM-CON treatments. In heart and semimembranosus (SM) muscles, expression of miR-22-3p was down-regulated (P < 0.05) in MIR-NR compared with SHAM-CON. In the gastrocnemius and semitendinosus muscle, miR-22-3p expression was unchanged (P > 0.05). The number of type I and IIa muscle fibers were greater (P < 0.05) for MIR-NR than SHAM-CON. Muscle fiber area of Type I, IIa or IIx fibers did not differ (P > 0.05) by treatment. The number of type IIx fibers did not differ (P > 0.05) between treatments. MIR-NR treatment appears to shift muscle fibers towards more oxidative metabolism and down-regulate HDAC-1, 3, and 11 and SIRT6 in SM. The systemic injection of antagomir-22-3P down-regulated miR-22-3p expression in circulation and in muscle tissues, which altered expression of HDAC/SIRT genes involved in muscle fiber type conversion and hypertrophy.

DATA DRIVEN AND CELL SPECIFIC DETERMINATION OF NUCLEI-ASSOCIATED ACTIN STRUCTURE

In the specialized field of cellular mechanosignaling, the intricate relationship between the cytoskeleton and nucleus is crucial for determining the behavior and fate of mesenchymal stem cells (MSCs). Existing analytical methods for filamentous actin fibers (F-actin) suffer from issues of accuracy and reproducibility. To address this, our research introduces a significant advancement in image analysis by utilizing two deep-learning segmentation Convolutional Neural Networks (CNNs) based on U-Net architecture. This algorithm precisely quantifies F-actin and offers reproducible data from 3D confocal microscopy images. Our CNNs automatically extract the 3D shape of both the nucleus and individual actin fibers, thereby enabling the geometric reconstruction of these critical cellular components. We applied this methodology to MSCs exposed to low-intensity vibration, and hypothesized that mechanical stimuli will induce perinuclear actin remodeling. Confocal Z-stack images of MSCs were captured using a 40x oil lens and a Zeiss LSM 900 microscope. Nucleus and F-actin structures were stained with Hoechst 33342 and Phalloidin, respectively. Nucleus-based images were employed to mask and isolate actin fibers within the nuclear vicinity. A specialized deep-learning segmentation model was engineered within the PyTorch framework. For model training, a selective 2% of nuclei and F-actin images were annotated. Specifically, three layers from each of six representative nuclei, among approximately 500 cross-sectional layers, were meticulously selected; a similar approach was employed for actin. The model underwent 200 epochs of training. Post-training, the deep-learning model was employed to process all collected cross-sectional images of F-actin and nuclei. A subsequent analytical step involved the scrutiny of intersecting segmented fibers between consecutive layers for geometrically accurate actin fiber reconstruction. We analyzed 102 control and 110 vibration-treated mesenchymal stem cells (MSCs) by utilizing our deep-learning-based reconstruction algorithm on confocal Z-stack images. Our data revealed an 8% decrease in nuclear height from 5.73 µm to 5.28 µm (p < 0.001) upon application of low-intensity vibration. In contrast, the two groups observed no significant difference in nuclear volume. Accompanying these changes at the nuclear level, the following changes in the F-actin cytoskeleton were observed upon LIV application. The total number of actin filaments per cell increased from 117 to 150. The average volume of individual actin fibers rose from 0.40 µm³ to 0.43 µm³. Notably, the volume of fibers at the apical nuclear surface increased from 0.35 µm³ to 0.46 µm³. While the average length of actin fibers in the apical nuclear surface remained largely unchanged due to the addition of smaller fibers in LIV groups, the LIV group had a larger number of fibers that were larger than 15µm.

Topological structural characteristics in patients with systemic lupus erythematosus with and without neuropsychiatric symptoms

PurposeThis study investigated the topological structural characteristics of systemic lupus erythematosus (SLE) with and without neuropsychiatric symptoms (NPSLE and non-NPSLE), and explore their clinical implications.MethodsWe prospectively recruited 50 patients with...

Satellite cell distribution in the medial rectus muscle in cadavers

Background: This study aimed to elucidate the potential usefulness of the medial rectus muscle of cadavers for research on satellite cells.Methods: Twenty-four medial rectus muscles were obtained from 12 cadavers. The control group included six medial rectus muscles from three live adults without brain activity. The muscle fiber diameter and distribution of satellite cells were measured and compared. Immunohistochemistry for myosin heavy chain and the transcription factor PAX7 was performed, and the distributions of myocytes and satellite cells were evaluated.Results: The average muscle fiber diameter was 142.18±36.49 μm in the cadaver group and 149.34±15.26 μm in the control group, and there was no significant difference between the two groups (p=0.38). The ratio of PAX7(+) cells to the number of muscle fibers was 0.056±0.015 in the control group and 0.006±0.006 in the cadaver group, reflecting a significant difference (p<0.05).Conclusions: The medial rectus muscles of cadavers can be helpful in studying anatomical morphology; however, their usefulness in muscle satellite cell research appears to be limited.

Group-random algorithm to generate representative volume element models for composites

One of the most commonly used methods for characterizing the mechanical properties of discontinuous fiber reinforced composites (DFRC) is to establish a Representative Volume Element (RVE) model and perform finite element (FE) analysis. However, FE analysis on RVE models established by traditional sampling algorithms is often computationally expensive due to the large size of RVE that is required to be statistically representative of the composite. To address this issue, this paper proposes a new approach for constructing RVE models with more accurate description of fiber orientation, aiming to make the FE modelling more efficient by using an RVE with small size. When establishing RVE models with given target fiber orientation tensor, it is very challenging to accurately capture the orientation of fibers. In order to mitigate the error between the orientation tensor reconstructed by fibers generated in the RVE and the target orientation tensor, a group-random algorithm is proposed in the current work to generate RVE models. Unlike the traditional algorithm, in which fibers are sampled one by one in the RVE, the group-random algorithm samples a group of four fibers at one time in order to eliminate the error of the off-diagonal components of the reconstructed orientation tensor in the principal coordinate system. Then a modification tensor is further introduced to mitigate the error of the diagonal components of the reconstructed orientation tensor. Simulation results show that the orientation tensor error could be significantly reduced by the group-random algorithm even for the RVE with low number of fibers. The merits of the group-random algorithm are also witnessed by the stability and accuracy of predicting the elastic constants of composite materials through RVE modeling. It is thus concluded that the major advantage of this work is to provide an alternatively feasible strategy to substantially improve computational efficiency of RVE modelling.

Loading rate effects on multifiber pullout resistance of smooth steel fibers in ultra-high-performance concrete

This study investigated the multi-fiber pullout resistance of high-strength smooth steel fibers embedded in ultra-high-performance concrete (UHPC) at different loading rates. To discover the source of the fiber group effect on fiber pullout resistance, multi-fiber pullout tests were employed by changing the number of fibers, fiber-to-fiber distance, and difference in embedded lengths. The main source of the fiber group effect was found to be the reduced contact pressure per fiber, in the specimens containing more fibers, generated by matrix shrinkage: the fiber pullout stress at the static loading rate (0.0167 mm/s) decreased from 786.58 to 618.59 MPa (21.4 % reduction) as the number of fibers increased from 1 to 25. The equivalent bond strength of smooth steel fiber in UHPC generally increased from 4.5–5.2 to 5.9–7.1 MPa as the loading rate increased from 0.0167 to 1.67 mm/s. The favorable rate-sensitive pullout resistance of multi-fiber pullout specimens was notably affected by the number of fibers and fiber distance: the specimens containing nine fibers with a 2.7 mm fiber distance produced the highest dynamic increase factor (1.37) owing to enhanced interactions between interfacial cracks.

The mode detangler.

Astrophotonics aims to transfer photonic technology to the development of compact astronomical instruments. However, light coupling from a multimode fiber, typically adopted in modern observatories, to a single-mode photonic device still poses a challenge. Though a photonic lantern can enable this transition in a low-loss way, it requires that the number of single-mode fibers (SMFs) at the output is the same as the number of guided modes in the multimode fiber, resulting in a cumbersome fan-out of many single-mode devices to be connected. Herein, we invent an active device in a waveguide form called "the mode detangler" (MD). We show that it can adaptively transform a complex light field from a multimode fiber to a single-mode-like spot. In this way, only one single-mode device is required at the end. The path leading to the idea and the theory behind the mode detangling effect is explained, followed by numerical simulations and experimental demonstrations using a few-mode fiber as proof of concept. We believe this device has the potential to address the multimode-to-single-mode conversion challenge in astrophotonics but also sheds light on (de)multiplexing applications regarding spatial mode technology in optical communications.

Comparative Histological Study on Teat of Domestic Animals

The present study was executed at Department of Veterinary Anatomy, College of Veterinary Science, Sri Venkateswara Veterinary University, Tirupati, Andhra Pradesh, India during the period of July, 2020 to October, 2021 to find the possible differences in histology of teat among domestic animals. The study was conducted on teat of domestic animals i.e., 6 adult buffalo, 6 cattle, 15 sheep, 15 goats, 6 dogs and 6 pigs. The wall of the teat consisted of three layers in buffalo, cattle, sheep, goat and pig i.e., outer skin, middle muscular and inner connective tissue layer. But in dog only two layers were present i.e., outer skin and inner fibromuscular layer. Each teat consisted of single teat sinus in buffalo, cattle, sheep and goat, whereas in pig each teat showed two teat sinuses and eleven sinuses in dog. In buffalo and cattle, isolated clusters of glandular structures were seen between the smooth muscle fibers which were absent in sheep, pig and dog. Further, in sheep and goat, accessory glands were noted in the dermis and in middle layer. Sweat glands were noticed only in sheep and goat. In cattle and pig, hair follicles were not distinct and they were surrounded by numerous sebaceous glands. The number of collagen fibers in dermis of teat were more dense in cattle than other domestic animals. Elastic fibers were numerous in dog and moderate in the dermis of teat in buffalo, cattle, sheep and very few in goat.

Effect of Lactational Low-Protein Diet on Skeletal Muscle during Adulthood and Ageing in Male and Female Mouse Offspring.

Sarcopenia is characterised by the loss of skeletal muscle mass and function, which leads to a high risk of increased morbidity and mortality. Maternal malnutrition has been linked to impaired development of skeletal muscle of the offspring; however, there are limited studies that report the long-term effect of a maternal low-protein diet during lactation on the ageing of skeletal muscles. This study aimed to examine how a maternal low-protein diet (LPD) during lactation affects skeletal muscle ageing in the offspring. Pups born from control mothers were lactated by mothers fed with an LPD. Post-weaning, mice were either maintained on an LPD or switched to a control, normal-protein diet (NPD). In males, an LPD mainly affected the size of the myofibres without a major effect on fibre number and led to reduced grip strength in ageing mice (24 months). Female mice from mothers on an LPD had a lower body and muscle weight at weaning but caught up with control mice at 3 months. During ageing, the muscle weight, myofibre number and survival rate of female pups were significantly affected. These findings highlight the effect of an LPD during lactation on skeletal muscle ageing, the lifespan of offspring and the importance of sexual dimorphism in response to dietary challenges.

The biliary atresia susceptibility gene, EFEMP1, regulates extrahepatic bile duct elastic fiber formation and mechanics

IntroductionEGF-Containing Fibulin Extracellular Matrix Protein 1 (EFEMP1, also called fibulin-3) is an extracellular matrix protein linked in a genome-wide association study to biliary atresia, a fibrotic disease of the neonatal extrahepatic bile duct. Fibulin-3 is deposited in most tissues and Efemp1 null mice have decreased elastic fibers in visceral fascia; however, fibulin-3 does not have a role in the development of large elastic fibers and its overall function in the extrahepatic bile ducts remains unclear. MethodsWe used staining and histology to define the amount and organization of key extracellular matrix components in the extrahepatic bile ducts. We also repurposed pressure myography, a technique heretofore applied to the vasculature, to determine the contribution of elastin and fibulin-3 to extrahepatic bile duct mechanics. We examined extrahepatic bile duct structure and mechanics in three models: neonatal vs. adult rat ducts (n=6 each), elastase-treated adult rat ducts (n=6-7 each), and Efemp1+/- vs. wild type mouse ducts (n=6 each). ResultsWe demonstrated that fibulin-3 is expressed in the submucosa of both neonatal and adult mouse, rat and human extrahepatic bile ducts and that, in adult Efemp1+/- mouse ducts, elastin organization into fibers is decreased by approximately half. Pressure myography showed that Efemp1+/- ducts have altered mechanics compared to control ducts, with Efemp1+/- ducts displaying significant stretch compared to controls (p=0.0376); these changes in stretch are similar to those observed in elastase-treated compared to normal ducts (p<0.0001) and in neonatal ducts compared to adult ducts (p< 0.0001). ConclusionFibulin-3 has an important role in the formation of elastic fibers and the mechanical properties of the extrahepatic bile duct. This provides functional relevance for the biliary atresia susceptibility gene EFEMP1. Impact and ImplicationsThe gene EFEMP1 was found via a genome wide association study to be a susceptibility gene for the neonatal disease biliary atresia. EFEMP1 encodes the protein fibulin-3, which regulates elastic fiber organization in the extrahepatic bile duct (EHBD), the major site of disease in biliary atresia. We showed that neonatal EHBDs as well as mice heterozygous for Efemp1 have decreased numbers of elastic fibers, and that this alters EHBD mechanics. This work is important for understanding the mechanism of biliary atresia, in particular susceptibility to obstruction.

Spatiotemporal Characterization of Microstructure Morphology, Mechanical Properties and Bone Remodeling of Rat Tibia Under Uniaxial Compressive Overload Loading.

Bone tissue is subjected to increased mechanical stress during high-intensity work. Inadequate bone remodeling reparability can result in the continuous accumulation of microdamage, leading to stress fractures. The aim of this work was to investigate the characteristics and repair mechanisms of tibial microdamage under several degrees of overload. Also, we aimed at better understanding the effects of overload on the multi-scale structure and mechanical properties of bone. Sixty 5-month female rats were divided into three groups with different time points. Micro-CT was used to evaluate the three-dimensional microstructure, and three-point bending, quasi-static fracture toughness and creep mechanical test were carried out to evaluate the mechanical properties. SEM was used to observe the morphological characteristics of fracture surfaces. Section staining was used to count the microdamage parameters and numbers of osteoblasts and osteoclasts. The microarchitectures of cancellous and cortical bones in the three overload groups showed different degrees of damage. Overload led to a messy crystal structure of cortical bone, with slender microcracks mixed in, and a large number of broken fibers of cancellous bone. The properties associated with the elastic plasticity, fracture toughness, and viscoelasticity of cortical bone reduced in three groups, with that corresponding to day 30 presenting the highest damage. The accumulation of microdamage mainly occurred in the first 14days, that is, the crack density peaked on day 14. Peak-targeted bone remodeling of cortical and cancellous bones occurred mainly between days 14 and 30. The influence of overload mechanical environment on bone quality at different time points was deeply investigated, which is of great significance for the etiology and treatment of stress fractures.

Composite suture material based on polylactide accelerates the healing of surgical wounds in in vivo experiment.

In laboratory conditions, composite sutures based on polylactide (PLA) containing chitin nanofibrils modified with polyethylene glycol (CN-PEG) and poviargol (silver nanoparticles stabilized with poly(N-vinylpyrrolidone)) were obtained, studied, and used as a prototype. Surgical sutures threads with the addition of CN-PEG have stable mechanical properties both in air and in a buffer simulating the environment of a living organism. The yield strength of oriented threads decreased by an average of 15%, whereas for non-oriented threads the decrease was 3-4 times. The strength values in simple units of unfilled PLA, PLA containing 5 wt % CN-PEG, and PLA with 1 wt % Poviargol were on average 50% higher than the national standard 31620-2012. The results of in vivo experiments on albino rats (cross-linking skin and muscle tissue in the linea alba area) showed that composite sutures are best for suturing muscle tissue, whereas unfilled PLA sutures are more suitable for suturing skin. When suturing muscle tissue, suturing with composite sutures increased the number of collagen fibers of different diameters.

Parallel Analogy Method for Measuring FRD of the FASOT-IFU

A fiber integral field unit (IFU) was chosen for the Fiber Array Solar Optical Telescope (FASOT) to obtain high-spectral-resolution polarization solar spectral images. This IFU features a dual-array-end design, complemented by a dozen slit ends. Each consists of 2 sub-slits corresponding to the dual array ends. In order to accurately and quickly measure the focal ratio degradation of 8064 fibers in FASOT-IFU, a parallel analogy method (PAM) for FASOT-IFU was proposed. This method primarily relies on characterizing the focal ratio based on the full-width at half-maximum (FWHM) of the fiber’s output spot, and the linear relationship between the output focal ratio of the spot and the FWHM. By precisely calculating the focal ratio of the positioning fiber in the FASOT-IFU and treating it as a reference, the output focal ratio of the working fiber can be obtained by comparing the FWHM of the working fiber spot and the positioning fiber spot at the same emission distance. The average value of the output focal ratio by PAM corresponding to the 4032 fibers from Array A of the IFU is 6.0 and the standard deviation is 0.6. The values corresponding to the Array B are 6.2 and 0.40, respectively. The mean value exceeds the contractually specified F/5.5, and the proportion of optical fibers with a focal ratio greater than 5.5 accounts for 88% of the total number of optical fibers, meeting the design requirements of the FASOT system.

Digestate Improves Stinging Nettle (Urtica dioica) Growth and Fiber Production at a Chlor-Alkali Site.

Marginal lands have been proposed to produce non-food crop biomass for energy or green materials. For this purpose, the selection, implementation, and growth optimization of plant species on such lands are key elements to investigate to achieve relevant plant yields. Stinging nettle (Urtica dioica) is a herbaceous perennial that grows spontaneously on contaminated lands and was described as suitable to produce fibers for material applications. Two mercury-contaminated soils from industrial wastelands with different properties (grassland soil and sediment landfill) were used in this study to assess the potential growth of stinging nettle in a greenhouse mesocosm experiment. Two organic amendments were studied for their impact on nettle growth. The solid digestate from organic food wastes significantly doubled plant biomass whereas the compost from green wastes had a lower impact. The highest doses of organic amendments significantly increased the number of fibers, which doubled following digestate application, while reducing leaf Hg concentration. Both amendments significantly improved soil respiration and enzymatic activities linked to the microbial biomass in the soil from the sediment landfill by the end of the experiment. In the context of a phytomanagement scenario, solid digestate would be a preferred amendment resource to improve nettle production on industrial wastelands.

Multiscale fatigue life prediction model for CFRP laminates considering the mechanical degradation of its constituents and the local stress concentration of the matrix

In the present research, a novel approach for predicting the fatigue life of composites is proposed using a multiscale fatigue model. This model considers two critical physical phenomena that occur in CFRP laminates under tension-tension cyclic loading – the degradation of the physical properties of CFRP constituents and the localized stress concentrations within the matrix. To achieve this, Mori-Tanaka’s mean field theory, a well-known micromechanics model, is employed to consider the deterioration of material properties in various phases, which is dependent on the applied stress level. Localized stress concentration phenomena within the matrix of a composite material are common when CFRP laminate is subjected to cyclic loading. The localized stress concentration on a matrix with different numbers of fibers and orientations using representative volume elements (RVE) is investigated. Two other scales of failure criteria are defined to evaluate its constituent at the material level and ply level at the macroscale. A comparison with fatigue experiment data of AS4/3501-6 composite shows good reliability of the proposed multiscale fatigue model.

The Exploratory Study of the PTEN-AKT/mTOR Signaling Pathway in the Corresponding Dorsal Root Ganglion during Compensatory Repair via Small Gap Amplification in Sciatic Nerve Injury.

Peripheral nerve injury is a challenging orthopedic issue in clinical management that often leads to limb dysfunction or even disability in severe cases. A thorough exploration of the repair process of peripheral nerve injury and the underlying mechanism contributes to formulate more effective therapeutic strategies. In the present study, we established a sciatic nerve transection injury model in Sprague-Dawley (SD) rats. A 12-week compensatory repair of sciatic nerve transection injury using a chitin cannula for small gap anastomosis was then performed via sleeve jointing the proximal common peroneal nerve to the distal tibial nerve and common peroneal nerve, with a 2 mm interval. Compensatory repair via small gap amplification was observed via gross observation of nerve specimen, osmic acid staining, and electrophysiological stimulation of sciatic nerve branches of the tibial and common peroneal nerve. Rat limbs were observed, and the functional recovery of effector muscles of the gastrocnemius and tibialis anterior muscles was assessed through weighing the muscle wet weight, Hematoxylin and Eosin (H&E) staining, and muscle strength detection. H&E staining, Masson staining, and toluidine blue staining were performed to observe the morphological changes of the dorsal root ganglion. Positive expressions of key proteins involved in the Phosphatase and tensin homologue deleted on chromosome ten (PTEN)-protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway, including PTEN, AKT, mTOR, Toll-like receptor 4 (TLR4), and Caspase9 in the dorsal root ganglion during compensatory repair of sciatic nerve after injury via small gap amplification, were detected by immunohistochemical staining. It is found that the compensatory repair of sciatic nerve transection injury using a chitin cannula for small gap anastomosis via sleeve jointing effectively restored the continuity, number of myelinated nerve fibers, and nerve conduction velocity. It promoted toe abduction recovery, improved muscle fiber morphology and increased the wet weight and muscle strength of the gastrocnemius muscle and tibialis anterior muscle. Moreover, it increased the number of neurons and nerve fibers, and improved their morphology. Downregulated PTEN, TLR4, and Caspase9 in the dorsal root ganglia and upregulated AKT and mTOR were observed after small gap amplification than those of the transection injury group, which were closer to those of the control group. Compensatory repair of sciatic nerve transection injury using a chitin cannula for small gap anastomosis via sleeve jointing can restore the morphology and function of the sciatic nerve, effector muscles, and corresponding dorsal root ganglia by activating the PTEN-AKT/mTOR signaling pathway in the dorsal root ganglia. Our findings provide novel therapeutic targets for peripheral nerve injuries.

End effect and cut strategy of single-oriented one-dimensional fiber composites with high thermal conductivity

Fiber composite materials with high thermal conductivity are increasingly important in practical applications, particularly for efficient heat-dissipating shell packaging materials. This paper uses random position generation and finite element simulation to investigate the end effect in single-oriented one-dimensional fiber composites, significantly reducing their thermal conductivity. The analysis of the end region reveals that the end effect is caused by the deviation in fiber number at both ends of the composite material. A relationship between the end region thickness, fiber length, and composite thickness is established. A new optimal end-cutting strategy is proposed to enhance thermal conductivity by simulating the representative volume element. This strategy can improve the thermal conductivity by up to five times. Additionally, a new model for calculating the thermal conductivity of single-oriented fiber composites is presented. The model was experimentally validated by testing the thermal conductivity of a prepared sample, showing an error rate of less than 3 %, thereby confirming the model's accuracy.

Impact of Eccentric Exercise Interventions with Small and Large Ranges of Motion on Rat Skeletal Muscle Tissue and Muscle Force Production.

Eccentric training induces greater hypertrophy while causing more muscle damage than concentric training. This study examined the effects of small-range eccentric contractions (SR-ECCs) and large-range eccentric contractions (LR-ECCs) on muscle morphology, contractility, and damage in rats. Thirty male Fischer 344 rats were divided into five groups: small-range ECC single-bout (SR-ECCSB, n = 4), large-range ECC single-bout (LR-ECCSB, n = 4), SR-ECC intervention (SR-ECCIntv, n = 7), LR-ECC intervention (LR-ECCIntv, n = 8), and control (Cont, n = 7). These groups underwent transcutaneous electrical stimulation involving 80 ECCs twice a week for four weeks. The results indicated that the LR-ECCSB group had more Evans blue dye-positive fibers than other groups. The SR-ECCIntv group showed no increase in the mean myofiber cross-sectional area. However, Pax7+ and Ki67+ cells significantly increased in both ECCIntv groups compared to the Cont group, and the connective tissue area was significantly greater in the LR-ECCIntv than in others. Muscle force was lower in both ECCIntv groups compared to the Cont group. These findings suggest that SR-ECC intervention may induce a smaller increase in the number of fibers with a large myofiber cross-sectional area and satellite cell proliferation with less muscle damage and myofibrosis compared to LR-ECCs.

Numerical and experimental behavior of fiber reinforced polymer type and layer number effect on the flexural properties of heat-treated black pine wood

Heat treatment is one of the environmentally friendly methods applied to improve the structural properties of wooden materials. While heat treatment improves some properties of wood material, it also negatively affects its mechanical properties depending on the heat treatment conditions applied. The decrease in mechanical properties due to heat treatment limits the use of wood material in various applications requiring mechanical strength. For this purpose, various fiber-reinforced polymers have been used in recent years. In this study, it was aimed to experimentally and numerically examine the flexural properties of unheat-treated and heat-treated black pine (Pinus nigra Arnold.) wood reinforced 1, 2 and 3 times with carbon, glass and aramid. Following the experimental flexural tests, the samples were modeled and analyzed in the finite element software program. The average flexural strength of the heat-treated sample is 11.72% lower, and the elasticity modulus is 1.23% lower than the unheat-treated sample.It has been determined that carbon-based polymer fabrics, among fiber-reinforced polymer fabrics, have the best reinforcement effect. The flexural strength of the UHT-C-3 sample is 6.1% and the elasticity modulus is 3.52% higher than the UHT-C-1 coded sample. Compared to the sample without reinforcement, flexural strength increased by 30% and elasticity modulus increased by 7%. It is seen that as the number of fiber reinforced polymer layers increases, the flexural properties also increase. When the experimental and numerical analysis results were examined, the flexural strength and modulus of elasticity values gave similar results at the R2: 0.88–0.99 level. In addition to technologies using kinds of reinforcement evaluated in conservation applications, it may be utilized for numerical analysis in the field of repairing or reinforcing different grades, patterns, and types of reinforcement in already-existing wooden structures.