Strength Recovery Rate Research Articles

Effects of toluene-di-isocyanate microcapsules on the frost resistance and self-repairing capability of concrete under freeze-thaw cycles

Concrete buildings used in severe cold regions are susceptible to freeze-thaw damage, resulting in internal cracking and surface spalling of concrete. Microcapsules can self-repair concrete cracks and improve the durability of concrete. This paper focuses on the effects of toluene-di-isocyanate (TDI) microcapsules on the frost resistance and self-repairing capability of concrete under freeze-thaw cycles. The mass and mechanical properties of concrete were measured before and after freeze-thaw cycles. The pore size distribution and microstructure of the concrete were characterized using nuclear magnetic resonance and scanning electron microscopy (SEM). The mechanical properties and permeability of freeze-thaw damaged concrete were assessed by compressive strength tests and rapid chloride migration (RCM) tests after self-repairing. The frost resistance and self-repairing capability of concrete containing microcapsules were also evaluated by ultrasonic test. The results showed that the concrete containing nano-SiO2/paraffin/PE wax encapsulated TDI microcapsules (CON3) had better frost resistance and self-repairing capability than the concrete containing other microcapsules. After 100 freeze-thaw cycles, the mass loss rate and compressive strength loss rate of CON3 were only 1.63% and 13.6%, respectively. After 7 d of self-repairing, SEM images showed that repairing products with network structure appeared in the pores of CON3, which improved the microstructure of concrete. The harmful pores proportion, compressive strength recovery rate, chloride diffusion coefficient recovery rate, maximum amplitude and dominant frequency maximum amplitude of CON3 were 47.8%, 96.9%, 84.6%, 77.99 mV and 8.37 mV, respectively.

Finite Element Analysis of Mechanical Behavior of Assembled SRC Beam-CFST Column Composite Frame

Prefabricated buildings have the advantages of good component quality, fast construction speed and less construction waste, which is an important measure to implement ecological civilization, save resources, protect the environment and reduce pollution. The composite structure of section steel and concrete gives full play to the advantages of light weight, high strength, assembling construction and high recovery rate of steel. However, the construction method of assembly is still in the research stage. In order to explore the key problems in engineering application, such as mechanical performance, material behavior, failure phenomenon, connection design etc. of SRC beam-CFST column composite frame (hereinafter referred to as “composite frame”). On the basis of the experimental results of exterior joints in the early stage, the whole process mechanical behavior of composite frames under vertical load and horizontal low cyclic load is studied by using ABAQUS finite element analysis software. The research shows that the assembled connection mode has better static and seismic performance, and the material performance is fully utilized. The mechanical performance of the full welded and bolt-welded hybrid connection is similar. Increasing the thickness of the ring plate and the height of the beam section can improve the bearing capacity and energy dissipation capacity.

Evaluation on the Strength Recovery Rate of Concrete Using Surface Coating Agent

Cracks and voids of concrete cause the loss of durability. When the cracks reach to the surface of reinforced concrete structures, they can repair by various methods, but there are no effective repairing methods for latent faults or micro-cracks caused by load repetition because they cannot detect by surface state. In this study, we examined the presence or absence of self-repair performance of concrete mixed with the admixture using the coating material for repair, which has been used for a long time. Thus, the basic characteristics of concrete mixed with admixture were identified and self-repair performance was confirmed through experiments. As a result of considering the recovery of the strength of damaged concrete, concrete mixed with a surface coating agent showed a greater recovery effect than concrete mixed with non-mixed concrete. This effect is greater with the age of the damaged material. This shows that even if the repair coating material is mixed as an admixture, the crystal proliferation effect is maintained, and it is confirmed that the concrete mixed with the admixture has self-repairing performance.

Muscle Strength Does Not Adapt From a Second to Third Bout of Eccentric Contractions: A Systematic Review and Meta-Analysis of the Repeated Bout Effect

Lindsay, A, Abbott, G, Ingalls, CP, and Baumann, CW. Muscle strength does not adapt from a second to third bout of eccentric contractions: A systematic review and meta-analysis of the repeated bout effect. J Strength Cond Res 35(2): 576-584, 2021-The greatest muscle strength adaptations to repeated bouts of eccentric contractions (ECC) occur after the initial injury, with little to no change in subsequent bouts. However, because of the disparity in injury models, it is unknown whether three or more bouts provide further adaptation. Therefore, we performed a systematic review of the literature to evaluate whether a third bout of skeletal muscle ECC impacts immediate strength loss and rate of strength recovery compared with a second bout. A search of the literature in Web of Science, SCOPUS, Medline, and the American College of Sports Medicine database was conducted between May and September 2019 using the keywords eccentric contraction or lengthening contraction and muscle and repeated or multiple, and bout. Eleven studies with 12 experimental groups, using 72 human subjects, 48 mice, and 11 rabbits, met the inclusion criteria. A meta-analysis using a random effects model and effect sizes (ESs; Hedges' g) calculated from the standardized mean differences was completed. Calculated ESs for immediate strength loss provided no evidence that a third bout of ECC results in greater loss of strength compared with a second bout (ES = -0.12, 95% confidence interval [CI] = -0.41 to 0.17). Furthermore, the rate of strength recovery was not different between a second and third bout (ES = -0.15, 95% CI = -1.01 to 0.70). These results indicate a third bout of skeletal muscle ECC does not improve indices of strength loss or rate of strength recovery compared with a second bout. Therefore, coaches and athletes should expect some level of persistent weakness after each of their initial training sessions involving ECC, and the faster recovery of strength deficits in the second bout documented by previous research is not different from a third bout.

Study on Progressive Damage Assessment and Scarf Repair of Composite Honeycomb Structure

As the widely application of composite honeycomb structure in aircraft Structural Significant Items(SSI) and other structures, the damage assessment and repair scheme because of the impact and other damages have become one of the most concerned issues in the civil aircraft composite structures. In view of the progressive damage assessment of composite honeycomb structure and it's adhesively scarf repair parameter influence, the finite element model based on honeycomb core equivalent model and 3D solid units C3D8 and zero thickness cohesive force unit COH3D8 is established. A special USDFLD program is developed with FORTRAN for ABAQUAS using 3D Hashin criterion Besant criterion and B-K criterion to realize the damage simulation of composite panels, honeycomb cores and adhesive. The relationships between the structural strength recovery rate and the repair parameters such as patch oblique angle, extra layers layup angle and extra layers thickness are studied for the perforation injured honeycomb structure. The results show that the decrease in the patch oblique angle leading to an increase in the internal shear stress of the adhesive, the increase in the angle between the extra layers of the patch and the external load, and the increase in the thickness of the extra layers causing stress concentration and premature instability at the lap edge, will significantly reduce the strength recovery rate of the repaired honeycomb structure. The perfect patch form with 1:10 cut oblique angle and only one extra layer of 0° layup angle is concluded, which achieves the optimal strength recovery effectiveness, reaching 95.72% of the non-damaged honeycomb structure.

Mud Pack With Menthol and Arnica Montana Accelerates Recovery Following a High-Volume Resistance Training Session for Lower Body in Trained Men.

Bartolomei, S, Nigro, F, D'Amico, A, Cortesi, M, and Di Michele, R. Mud pack with menthol and Arnica montana accelerates recovery following a high-volume resistance training session for lower body in trained men. J Strength Cond Res 36(7): 1909-1915, 2022-The aim of this study was to compare the effects of a mud pack, containing menthol and Arnica montana, on the recovery responses following a high-volume resistance protocol. Ten resistance-trained men (mean ± SD: age = 25.3 ± 6.1 years; body mass = 79.1 ± 10.6 kg; height = 178.9 ± 7.5 cm) performed a high-volume resistance workout for lower body squat and leg extension, (5 sets of 10 reps at 70% of one repetition maximum for both exercises). All the subject used mud (MUD) or a placebo (PL) in randomized counterbalanced crossover design. MUD or PL were applied 4 times: 3, 19, 27, and 45 hours after the workout, on the skin surface above the quadriceps muscle of both legs. Muscle performance (countermovement jump power [CMJP], isokinetic leg press at 75 cm·s-1 and 25 cm·s-1 [ISOK75 and ISOK25, respectively], isometric squat [ISQ]), and morphology (muscle thickness of vastus lateralis [VLMT]), were measured before exercise (baseline [BL]), and 15 minutes (15P), 24 hours (24P), and 48 hours (48P) postexercise. In addition, muscle soreness was assessed at the same time points using a visual analog scale (VAS). No significant interactions (p > 0.05) between the trials were detected for CMJP, ISOK75, ISQ, and VLMT. A significant interaction between trials was noted for ISOK25 (p = 0.022) and for VAS (p = 0.001). ISOK25 was significantly (p < 0.01) reduced from BL at 15P, 24P and 48P in PL, whereas changes were significant (p < 0.05) at 15P and 24P only in MUD. The present findings indicate that MUD may enhance the recovery rate of strength and reduce muscle soreness after high-volume exercise. Muscle morphology do not seem to be influenced by mud packs.

The Effects Of Contrast With Compression Therapy On Muscle Recovery Post Exercise

Intense eccentric exercise causes muscle damage that leads to a decrease in subsequent performance. Accelerating muscle recovery between bouts of exercise minimizes the risk of injury and is essential for optimal athletic competitive performance. PURPOSE: The purpose of this study was to determine if the contrast with compression (CwC) therapy proprietary device by Solid State Inc was able to improve muscle recovery post intense eccentric exercise. METHODS: Ten physically active men (age = 21.3+2.1 years; height = 182 +8.5cms; weight = 88 + 19.5kg; body fat = 17.2+7%) completed two separate single-arm elbow flexor workouts on an isokinetic dynamometer. After one workout each participant received contrast with compression (CwC) therapy immediately after, 24h and 48h after the workout. After the other workout the same person received no treatment(CON). Post-exercise recovery of selected characteristics were measured at 1h, 24h, 48h and 72h. Comparisons were made between the CwC and CON groups using a Mixed Model ANOVA with repeated measures to identify time effects and an ANCOVA was used to identify interaction effects. A Bonferroni post-hoc test was used to assess timepoint differences in between interventions in recovery post eccentric exercise. A p≤0.05 was used for all analysis. RESULTS: CwC therapy post exercise resulted in a significantly faster recovery rate of strength and power to baseline levels (p=0.00) as well as a greater recovery of overall relative strength (p=0.004). Treatment with CwC significantly suppressed the post-exercise inflammatory response (p=0.05) and significantly reduced the secondary muscle damage response as measured by levels of Creatine Kinase post exercise. CwC therapy also resulted in a significantly quicker recovery of the maximal elbow flexion range of motion (p=0.00) within the hour post exercise. Lastly, participants experienced significantly less soreness 48 hours and 72 hours post-exercise with CwC therapy. CONCLUSION: Contrast with compression therapy significantly increases the recovery rate of muscle strength and power post eccentric exercise. CwC is also effective at reducing exercise associated muscle damage, delayed onset muscle soreness and mitigates the loss of range of motion post intense exercise.

Overlapped repair performance for carbon–PPS composites in vacuum-assisted thermal bonding

An overlapped repair with a continuous bonding area, was applied to carbon–PPS thermoplastic composites, and their strength recovery rate and failure behavior under mechanical loading were analyzed. This overlapped model has been designed to prevent the common and fundamental failures in conventional repair technologies through utilization of the volume fraction properties of continuous fibers. The same material was used for the parent and repair, and adhesion occurred via reversible thermal properties of the thermoplastic PPS polymer, without using additional adhesives. Under tensile and flexural loading, thickness ratios of 30% and 50% (damaged depth to the total thickness of the laminate) resulted in high strength recovery rates of 96% and 94%, respectively. The overlapped, bonded area on the surface of the parent material is the path of external load transfer between the parent and repair materials, maintaining uniform stress dispersion and increasing the fracture resistance.

Repair and cryogenic mechanical properties with resin film infused (RFI) GFRP in out-of-autoclave processing

Prepreg technology generates air pockets at the interface of laminates under heating and pressurization. The air pockets cause defects in the through-thickness direction. This includes poor adhesion between layers, which degrades material properties. Therefore, in this study, cryogenic mechanical properties were compared to obtain uniform properties by using prepreg laminated and resin film infused glass fiber reinforced plastic (GFRP) composites (“PP-only” and “RF-only”, respectively) while maintaining the constituent contents of the fiber and polymer. Moreover, stepped repair was applied to extend the life of composites. The results demonstrated that the stiffness of the composites improved, and the brittleness increased in cryogenic environments. In the case of PP-only, numerous voids were observed inside the polymer, which showed higher bending strength than RF-only; however, it exhibited significantly lower interfacial bonding strength. When applied to secondary bonding of stepped repair, RF-only as repair layers showed high strength recovery rate in homogeneous materials, and not in heterogeneous materials. In contrast, the high strength PP-only as a parent material and RF-only as repair layers showed relatively good interfacial bonding strength due to primary damage in the PP of a parent material. Hence, the RF-only can be considered useful as a repair material.

Effect of temperatures on self-healing capabilities of concrete with different shell composition microcapsules containing toluene-di-isocyanate

The ambient temperatures have significant effect on self-healing capabilities of concretes with microcapsules. Self-healing capabilities of mortars with different shell composition (paraffin, paraffin/PE wax and nano-SiO2/paraffin/PE wax) microcapsules containing toluene-di-isocyanate under the temperature of 10 °C, 30 °C, 50 °C and 60 °C were investigated in this paper. The compressive strength, chloride diffusion coefficient and pore size distribution of mortars containing microcapsules before and after self-healing were characterized by mechanical property test, rapid chloride migration test and nuclear magnetic resonance, respectively. The crack healing ratio of mortars during self-healing period were measured. The self-healing capabilities of mortars containing different microcapsules raised with the increase from 10 °C to 50 °C. Nevertheless, when the temperature reached 60 °C, the self-healing capability of the mortar containing paraffin microcapsules (AM1) decreased obviously, while the self-healing capabilities of the mortars containing paraffin/PE wax microcapsules (AM2) and nano-SiO2/paraffin/PE wax microcapsules (AM3) were almost unchanged. The self-healing capability of AM3 was superior to that of AM1 and AM2 at the same temperature. The compressive strength recovery rate, chloride diffusion coefficient recovery rate and harmful pores ratios of AM3 after pre-damaged at 50 °C for 7 d self-healing were 94.1%, 81.2% and 47.3%, respectively. When the ambient temperature reached 50 °C, the surface cracks of the mortar with three kinds of microcapsules could be completely self-healed in 5 h. However, when the temperature raised to 60 °C, the healing ratio of the crack in AM1 with a width of 0.4–0.5 mm decreased to 49.52% after 6 h self-healing. Meanwhile, the surface cracks of AM3 could be completely self-healed less than 3 h.

Effect of ion chelator on pore structure, mechanical property and self-healing capability of seawater exposed mortar

Ion chelator is a novel crystalline admixture used for improving self-healing capability of cementitious materials. Studies quantifying this self-healing behavior are limited to fresh-water making it unclear under seawater containing magnesium, sulfate and chloride ions. Therefore, the purpose of this paper is to investigate the effects of ion chelator on pore structure, mechanical property and self-healing capability of seawater exposed mortar. The pore size distribution was evaluated by nuclear magnetic resonance (NMR). The self-healing ability was quantified by compressive strength recovery and visible crack closure test, while the composition of crack healing products was analyzed by X-ray diffraction (XRD). The results indicated that ion chelator improves pore structure and compressive strength of mortar under seawater immersion. After 90 days seawater immersion, the proportion of harmful holes (>0.1 μm) in mortar with ion chelator (MCA) was 30.3%, which is lower than in control mortar (CM). The compressive strength of MCA under seawater for 90 days was 34.4 MPa, while that of CM was 27.4 MPa. The ion chelator enhanced the self-healing capability of pre-damaged mortar remarkably. After 28 days seawater immersion, compressive strength recovery rate of MCA under fresh-water and seawater was 94% and 80%, respectively. And the maximum crack width completely healed in MCA under seawater is up to 350 μm, while around 240 μm in MCA under fresh-water. XRD analysis revealed that the crack-healing products in MCA under seawater immersion were magnesium hydroxide and calcium carbonate.

Effect of granulated blast furnace slag on the self-healing capability of mortar incorporating crystalline admixture

Self-healing properties of cementitious materials is an important way to improve the durability of concrete. The effect of various granulated blast furnace slag (GBFS) contents on the self-healing properties of mortar with crystalline admixture (CA) were studied. The compressive strength recovery rate, water absorption rate and visual crack healing were used to evaluate the early age and structural cracks self-healing capability, and the self-healing products were studied by X-ray diffraction (XRD), scanning electron microscopy and energy spectrum analysis (SEM-EDS). The results show that CA ensures the self-healing properties, the mortar with CA and 10 wt. % GBFS has the highest self-healing capability, and the healing product is mainly composed of calcium carbonate.

Preparation and characterization of nano-SiO2/paraffin/PE wax composite shell microcapsules containing TDI for self-healing of cementitious materials

Cement concrete materials are prone to form internal micro-cracks during service, which can be self-healed via microcapsule method. In this paper, self-healing microcapsules were prepared through melt condensation method with nano-SiO2/paraffin/PE wax composite shell and toluene-di-isocyanate (TDI) healing agent. The core fraction and compactness of microcapsules were measured. Particle size distributions, morphologies, micromechanical properties and chemical structure of microcapsules were characterized by laser particle size analyzer, scanning electron microscopy (SEM), nanoindentation test and Fourier transform infrared spectroscopy (FTIR), respectively. Self-healing capability of mortars containing microcapsules was investigated. The results depicted that core fraction of nano-SiO2/paraffin/PE wax composite shell microcapsule was 72.6%, and the size of the microcapsules was mainly between 400 and 600 µm. Since nano-SiO2 was added to the shell material, the elastic modulus and hardness of the microcapsule reached 1.87 GPA and 61.67 MPa respectively, and the weight loss rate decreased by only 2.6% within 60 d. SEM showed that nano-SiO2/paraffin/PE wax composite shell microcapsules were regular spherical with rough surface, and the shell thickness was about 1/20 of the diameter. The result of FTIR indicated that TDI was encapsulated into the nano-SiO2/paraffin/PE wax composite shell successfully. The compressive strength recovery rate of the mortar containing nano-SiO2/paraffin/PE wax composite shell microcapsules was 87.8% after 60% fc0 pre-load for 10 d self-healing in air. Moreover, the nano-SiO2/paraffin/PE wax composite shell microcapsule could completely self-heal the surface crack of mortar with a maximum width of 0.48 mm within 4 h, which showed that it had good self-healing capability for cracks in cementitious materials.

Effect of proximal-distal brachial plexus block on short-term operation in a department of hand surgery

Objective To evaluate the effect of proximal-distal brachial plexus block for short-term operation in a department of hand surgery. Methods One hundred patients of both sexes, of American Society of Anesthesiologists physical status I or II, aged 18-64 yr, weighing 45-90 kg, undergoing palm and finger surgery, were divided into 2 groups (n=50 each) using a random number table method: proximal-distal brachial plexus block group (group A) and proximal brachial plexus block group (group B). In group A, 1% lidocaine 20 ml was given using the subclavian coracoid approach, and 0.35% ropivacaine was given for ulnar nerve, radial nerve and median nerve of forearm (5 ml for each nerve root). In group B, 0.35% ropivacaine 20 ml was given through the subclavian coracoid approach.Sufentanil 0.1 μg/kg was intravenously infused at 5 min before nerve block, and dexmedetomidine was intravenously infused over 10 min in a loading dose of 0.8 μg/kg followed by a continuous infusion of 0.4 μg·kg-1·h-1 until the end of operation at the same time.The blocking effect was assessed by pin-prick test at 15 min after administering local anesthetics, and the operation was started after the blocking effect was satisfactory.Muscle strength of upper arm was measured at 2, 3, 4, 6, 8, 10 and 12 h after administering local anesthetics (T1-7), the recovery of muscle strength (≥ grade 3) was recorded, and visual analogue scale scores were recorded at the same time.When visual analogue scale score ≥4, tramadol 100 mg was intramuscularly injected, and the requirement for tramadol was recorded.The occurrence of adverse events (local anesthetic intoxication, pneumothorax, anaphylaxis, nerve injury, nausea and vomiting, etc.) was recorded, and the tourniquet reaction was recorded. Results Compared with group B, the muscle strength recovery rate was significantly increased at T2-6 (P 0.05). Tramadol was used at T6 in group B and at T7 in group A. Conclusion Proximal-distal brachial plexus block can be safely and effectively used for short-term operation in a department of hand surgery and is beneficial to the rapid recovery of muscle strength after operation. Key words: Nerve block; Brachial plexus; Minor surgical procedures

Assessing the natural-healing behavior of adhesively bonded structures under dynamic loading

For adhesively bonded structures, maximizing their longevity under the aspect of minimizing costs of maintenance and repair are basically of high interest for the operator. Specifically, high-tech industries such as aeronautical, automotive or medicine are subject to very high standards in terms of quality, performance and safety. Hence, for stakeholders of such industries it is crucial to know how repeating damage cycles affect the structural integrity of a glued structure. The question which might arise is what minimum significant residual strength and fracture-healing recovery rate is needed in order to prevent a total structural collapse.To pursue such crucial issues, a novel study has been conducted for investigating the natural fracture-healing behavior of several well-established types of industrial adhesives. In doing so, an innovative test setup was utilized to identify new sophisticated damage parameters, which cannot be found in any technical data sheet of adhesive manufacturers. Thanks to both the utilization of an innovative test device and the application of the GF-concept, an independent material parameter was thereby ascertained, which is highly representative and suitable for characterizing dynamic damage behavior of real structures outside the lab. The remarkable findings revealed that only one distinct type of adhesive was suitable for showing significant fracture-healing behavior. This was empirically verified by different mechanical and fracture analytical benchmarks, such as bulk tensile strength, interface tensile strength and fracture resistance. The results obtained demonstrated the efficacy of the novel applied GF-concept for successfully evaluating both the damage tolerance and healing behavior of adhesively bonded structures. In conclusion, this examination showed that the inclusion of fracture analysis already in the adhesive selection and evaluation process is crucial for maximizing the quality, performance and safety of glued structures during lifetime operation.

Experimental and theoretical investigation on the effect of crack dimension on the crack-healing performance of Si3N4/SiCw composite ceramic

Si3N4/SiCw composite ceramic was selected for researching the crack-healing performance. Pre-cracks with different lengths were introduced on the tensile side of specimens by Vickers hardness tester. Subsequent to heat treatment at 1300 °C, it is able to completely heal a crack of 200 μm, thereby achieving a substantial strength recovery for pre-cracked specimens even with much longer cracks (1200 μm) after heat treatment at the optimal heating temperature of 1300 °C. Crack closure and strength recovery of the pre-cracked specimen is considered to be triggered by the creation of SiO2, liquid aluminosilicate and silicon yttrium oxide by the oxidation reaction as filling mechanism during heat treatment. There is a theoretical model proposed to demonstrate the strength recovery rate of pre-cracked specimens, and to predict that the strength ratio of pre-cracked specimens with different initial crack length after and before heat treatment at the same healing condition should be of the similar value, which it is confirmed by experimental results.

Low-Dose Rapamycin Facilitates Recovery from Exercise-Induced Muscle Injury

Rapamycin has been shown to have a dose-dependent effect on multiple signaling proteins in skeletal muscle cells that influence protein synthesis and calcium handling. However, it has yet to be determined if a low-dose of rapamycin impacts skeletal muscle during recovery from an exercise-induced injury. PURPOSE: To determine if low-dose rapamycin affects the rate of isometric strength recovery, muscle ubiquitination levels and markers of autophagy compared to saline control 14 days after exercise induced injury. METHODS: Mice were injected with either saline (SAL; 0.9%) or low-dose rapamycin (RAP; 10 μg/kg body weight) every other day for 2 weeks before and after a single bout of 150 eccentric contractions of the left anterior crural muscles. The recovery of strength of the anterior crural muscles was measured in vivo immediately, 7 days, and 14 days after injury induction. The magnitude of expression of beclin-1, ubiquitin, and ubiquitinated protein in injured and contralateral control TA muscles (i.e., primary anterior crural muscle) were analyzed via Western blot at 14 days after injury. RESULTS: Isometric twitch torque values did not differ between groups at any time point. No group differences in peak isometric tetanic torque were observed pre-injury, post-injury or 7 days following injury. However at 14 days, RAP mice recovered to pre-injury peak isometric torque values (Pre= 2.30 ± .07 Nmm; 14d= 2.25 ± 0.08 Nmm) while SAL group was significantly lower than pre-injury. At 14 days, RAP mice generated 15.4% higher maximal torque than SAL group (p = 0.04). Beclin-1 and free ubiquitin expression in TA muscles were significantly increased in both SAL (1.4-fold and 2.3-fold, respectively) and RAP (2.2-fold and 8.0-fold, respectively) mice at 14 days after injury compared to the uninjured muscle. The increase in the free ubiquitin in the injured muscle was 3.3-fold greater in the RAP treatment compared to SAL (p = 0.001). There were no significant changes in the ubiquitination of proteins among the groups at 14 days post-injury. CONCLUSION: Chronic low-dose rapamycin treatment in mice enhances recovery of skeletal muscle from eccentric contraction-induced injury at the 14th day and accentuates the upregulation of free ubiquitin.

Effect of microcapsule layout on crack repair

Similar rock specimens without microcapsules were prepared on the basis of similarity principle, and uniaxial compression tests were carried out to obtain the general law of rock fracture propagation. Microcapsules were mixed into rock specimens in three ways. The first way is uniform mixing. The second method is to add microcapsules at different levels. The third way is to add microcapsules along the crack propagation angle. The uniaxial preloading tests were carried out to obtain the compressive strength of the microcapsules. After the curing of 7d and 14d, three specimens were subjected to compressive test again and the strength recovery rate was calculated. Draw the following conclusions: after pre-compression repair, the compressive strength increases, indicating that microcapsules play a repair role; adding microcapsules along the average angle of crack propagation is the best way to repair the crack; the stress-strain curves show good elastic-plastic, the pressure relief curve is stable, and the residual strength is stable.

The Effect of Peroneal Muscle Strength on Functional Outcomes After the Modified Broström Procedure for Chronic Ankle Instability

Category: Sports Introduction/Purpose: Although the peroneal muscle is known to be a major dynamic lateral stabilizer of the ankle, few informations are available regarding the changes of muscle strength and relationship with the outcomes after lateral ligaments repair surgery. The purpose of this study was to identify the effects of peroneal strength on the validated functional outcome measures after the modified Broström procedure(MBP) for chronic ankle instability. Methods: Forty-one patients (41 ankles) underwent MBP using suture anchors were eligible and followed up to 2 years postoperatively. Functional evaluation consisted of the Foot and Ankle Outcome Score(FAOS), Foot and Ankle Ability Measure(FAAM). The changes of peroneal strength were evaluated using isokinetic dynamometer. Differences in the functional outcomes between the 3 groups divided according to recovery rate of peroneal strength were analysed. Results: Peak torque and total work for eversion in 60º/sec angular velocity significantly improved from a mean 8.1 Nm, 5.2 Nm preoperatively to 11.4 Nm, 6.9 Nm at postoperative 2 years, respectively (P &lt; .001, P = .038). Deficit ratio of peak torque for eversion significantly improved from a mean 38.6% to 17.4%, and a significant side to side difference was found (P = .011). There were no significant differences in FAOS, FAAM, and measurements of stress radiograph between the 3 groups. Conclusion: Although restoration of peroneal strength postoperatively was about 82.6% of unaffected ankle, patient-reported function in daily and sport activities were satisfactorily improved. Postoperative isokinetic strength of the peroneus demonstrated no statistically significant effects on the functional outcomes after MBP.

Performance optimization of one-component polyurethane healing agent for self-healing concrete

In this work, glass capsules containing one-component polyurethane healing agents are embedded in concrete to realize its self-healing properties. First, one-component polyurethane is diluted with acetone, and the viscosity, area of dispersion, surface tension, and bond strength of the resulting mixture are investigated. By encapsulating the diluted polyurethane inside quartz glass tubes, two different package types of capsules are prepared (capsules I and II), and their compatibility with concrete and survival rate are analyzed. In particular, the microscopic interface between the polyurethane and concrete phases is studied via scanning electron microscopy, while energy-dispersive X-ray spectroscopy is used to determine their elemental compositions. The mechanical properties of the produced self-healing concrete are examined by performing three-point bending tests, and the self-healing efficiency of the polyurethane healing agent is determined. When the acetone/polyurethane mass ratio is equal to 1:5, the viscosity and surface tension of the resulting mixture are low, while its healing effect is the strongest one. The strength recovery rate observed after 48 h of manual crack healing is 75%, and after two different types of glass capsules were placed into concrete, its flexural strength increased by 6–30%. However, the embedded glass capsules break after the crack formation in the self-healing concrete block. Finally, the strongest healing effect is observed for the self-healing concrete containing two type II capsules, which corresponds to the healing efficiency of 67%.