The Study of Enhanced Mechanical Properties for Cu/Gr/2024Al Composite

2024Al alloy powder as matrix material with nanocopper-modified graphene as reinforcement was studied to explore the effects of graphene on the tissue, hardness, friction performance of the composite. The Cu/Gr/2024Al composites were prepared via three-dimensional mixed powder and vacuum hot press sintering. The results found that the nanocopper-modified graphene could be uniformly distributed in the aluminum alloy matrix, and formed a good binding interface with the matrix material. When the graphene content was 0.75 wt.% and 1.0wt%, the impact yield strength and the hardness reached the maximum of 434.8 MPa and 118.4 HV5, which were 27.24% and 43.11% higher than that of 2024Al respectively. Furthermore, with the increase of nanocopper-modified graphene content, the corrosion resistance of composite materials in 3.5%Cl-concentration solution was improved.

Relationship between Eccentric-Exercise-Induced Loss in Muscle Function to Muscle Soreness and Tissue Hardness

It is well-known that unusual exercise, especially eccentric contraction (ECC), could cause delayed-onset muscle soreness. However, the factors related to the loss of muscle strength and range of motion (ROM) caused by eccentrically damaged muscle, such as increases in muscle soreness, tissue hardness, and pain threshold, have not been investigated in detail. Thus, this study was conducted to investigate the factors related to the loss of muscle strength and ROM caused by eccentrically damaged muscle in a large sample. Fifty-six sedentary healthy young male volunteers were instructed to perform 60 repetitions of ECC exercise. The outcome variables were measured before and 48 h after the ECC exercise. The results showed that a decrease in ROM was correlated to an increase in tissue hardness, whereas a decrease in muscle strength was correlated to an increase in muscle soreness. Our results suggested that tissue hardness must be controlled for ROM loss, and muscle soreness must be controlled for muscle-strength loss.

Effect of Exercise Volume on Plantar Microcirculation and Tissue Hardness in People With Type 2 Diabetes

Objective: Exercise has been reported to be beneficial for people with type 2 diabetes (T2DM), but exercise, especially weight-bearing exercise, may increase the risk of diabetic foot ulcers (DFUs). This study aimed to explore the associations between different volumes of weight-bearing physical activities and plantar microcirculation and tissue hardness in people with T2DM.Methods: 130 elderly people with T2DM were enrolled for this cross-sectional study. They were classified into the high exercise volume group and the low exercise volume group based on their weekly energy expenditure (metabolic equivalents per week) in the past year. Weekly energy expenditure was calculated using the International Physical Activity Questionnaire and the Compendium of Physical Activities. The plantar oxygen saturation (SO2) and soft tissue hardness of each participant’s right foot were measured.Results: A total of 80 participants completed the trial. The average exercise energy expenditure of the high exercise volume group and the low exercise volume group were significantly different (p < 0.05). The results showed that the SO2 of the high exercise volume group (67.25 ± 6.12%) was significantly higher than the low exercise volume group (63.75 ± 8.02%, p < 0.05). The plantar tissue hardness of the high exercise volume group was lower than the low exercise volume group in the big toe, midfoot and hindfoot regions (p < 0.05).Conclusion: This study demonstrates that higher volumes of exercise are associated with better plantar microcirculation and lower plantar tissue hardness in people with T2DM. The findings of this study indicate that weight-bearing exercise may not increase risk of developing diabetic foot ulcers.

An Investigation of Regional Plantar Soft Tissue Hardness and Its Potential Correlation with Plantar Pressure Distribution in Healthy Adults

Background. The plantar soft tissue plays a critical role in absorbing shocks and attenuating excessive stresses during walking. Plantar soft tissue property and plantar pressure are critical information for footwear design and clinical assessment. The aim of this study was to investigate the relationship between plantar soft tissue hardness and plantar pressure during walking. Methods. 59 healthy volunteers (27 males and 32 females, aged 20 to 82) participated in this study. The plantar surface was divided into five regions: lateral rearfoot, medial rearfoot, lateral midfoot, lateral forefoot, and medial forefoot, and the plantar tissue hardness was tested using Shore durometer in each region. Average dynamic pressures in each region were analyzed for the five regions corresponding to the hardness tests. The relationship between hardness and average dynamic pressure was analyzed in each region. Results. The average hardness of the plantar soft tissue in the above five regions is as follows: lateral rearfoot ( 34.49 ± 6.77 ), medial rearfoot ( 34.47 ± 6.64 ), lateral midfoot ( 27.95 ± 6.13 ), lateral forefoot ( 29.72 ± 5.47 ), and medial forefoot ( 28.58 ± 4.41 ). Differences of hardness were observed between age groups, and hardness of plantar soft tissues in forefoot regions increased with age ( P < 0.05 ). A negative relationship was found between plantar soft tissue hardness and pressure reduction at lateral rearfoot, medial rearfoot, and lateral midfoot ( P < 0.05 ). Conclusion. The hardness of plantar soft tissues changes with age in healthy individuals, and there is a trend of increasing hardness of the plantar soft tissue with age. The plantar soft tissue hardness increases with plantar pressure.

Non-invasive assessment of tissue oxygenation parameters in diabetic patients foot sole using near infrared spectroscopy

Background and Objective: Diabetic problems are more common in the lower extremity and linked with high mortality rate which affects public health system. The present study focused on monitoring the changes in tissue oxygenation concentrations using Near infrared spectroscopy system along with temperature and hardness of the foot tissues. Methods: Control subjects (without diabetes) and diabetic patients without neuropathy were selected for this study and three standard foot risk areas were considered. Standard induced ischemic stimulus was given to assess the response of the designed system and to analyze the changes in oxyhemoglobin and deoxyhemoglobin levels during venous occlusion. Results: Results showed significant differences in the tissue oxygenation index value in all three standard areas where oxygenation value at the foot areas were significantly low ( p < 0.05) in diabetic group as compared to control group. Also, significant difference were found in tissue hardness value when comparing between groups, where the diabetic group had significantly high ( p < 0.05) tissue hardness at area 5 and area 8 as compared to control groups. Conclusion: Therefore, the present study concludes that high tissue hardness had significant effect on tissue oxygenation index that affects vascular circulation and this condition could be assessable using NIRS technique in order to find risky areas at the foot sole.

Protein nanoribbons template enamel mineralization

As the hardest tissue formed by vertebrates, enamel represents nature’s engineering masterpiece with complex organizations of fibrous apatite crystals at the nanometer scale. Supramolecular assemblies of enamel matrix proteins (EMPs) play a key role as the structural scaffolds for regulating mineral morphology during enamel development. However, to achieve maximum tissue hardness, most organic content in enamel is digested and removed at the maturation stage, and thus knowledge of a structural protein template that could guide enamel mineralization is limited at this date. Herein, by examining a gene-modified mouse that lacked enzymatic degradation of EMPs, we demonstrate the presence of protein nanoribbons as the structural scaffolds in developing enamel matrix. Using in vitro mineralization assays we showed that both recombinant and enamel-tissue–based amelogenin nanoribbons are capable of guiding fibrous apatite nanocrystal formation. In accordance with our understanding of the natural process of enamel formation, templated crystal growth was achieved by interaction of amelogenin scaffolds with acidic macromolecules that facilitate the formation of an amorphous calcium phosphate precursor which gradually transforms into oriented apatite fibers along the protein nanoribbons. Furthermore, this study elucidated that matrix metalloproteinase-20 is a critical regulator of the enamel mineralization as only a recombinant analog of a MMP20-cleavage product of amelogenin was capable of guiding apatite mineralization. This study highlights that supramolecular assembly of the scaffold protein, its enzymatic processing, and its ability to interact with acidic carrier proteins are critical steps for proper enamel development.

Vacuum Massage in the Treatment of Scars

Vacuum massage is a noninvasive mechanical massage technique performed with a mechanical device that lifts the skin by means of suction to create and mobilize a skin fold. It was invented by a French engineer suffering from burn scars after a car accident and has since then been frequently used for the treatment of burn scars.The two most reported physical effects of vacuum massage were improvement of the tissue hardness and the elasticity of the skin. Besides physical effects, a variety of physiological effects are reported in the literature, for example, an increased number of fibroblasts and collagen fibers accompanied by an alteration of fibroblast phenotype and collagen orientation. Little information was found on the decrease of pain and itch due to vacuum massage.Although vacuum massage initially had been developed for the treatment of burn scars, a literature review found little evidence for the efficacy of this treatment. Variations in duration, amplitude, or frequency of the treatment have a substantial influence on collagen restructuring and reorientation, thus implying possible beneficial influences on the healing potential by mechanotransduction pathways. Vacuum massage may release the mechanical tension associated with scar retraction and thus induce apoptosis of myofibroblasts. Suggestions for future research include upscaling the study design, investigating the molecular pathways and dose dependency, comparing effects in different stages of repair, including evolutive parameters and the use of more objective assessment tools.