Experimental Research on the Preparation of K2CO3/Expanded Vermiculite Composite Energy Storage Material.

Thermochemical adsorption energy storage is a potential energy utilization technology. Among these technologies, the composite energy storage material prepared by K2CO3 and expanded vermiculite (EVM) shows excellent performance. In this paper, the influence of the preparation process using the impregnation method and vacuum impregnation method on K2CO3/EVM composite material is studied. The preparation plan is further optimized with the solution concentration and the expanded vermiculite particle size as variables. In the experiment, mercury intrusion porosimetry (MIP) is used to measure the porosity and other parameters. Additionally, with the help of scanning electron microscopy (SEM), the morphological characteristics of the materials are obtained from a microscopic point of view. The effects of different preparation parameters are evaluated by comparing the experimental results. The results show that the K2CO3 specific gravity of the composite material increases with the increase of the vacuum degree, up to 70.440 wt.% (the vacuum degree is 6.7 kPa). Expanded vermiculite with a large particle size (3~6 mm) can carry more K2CO3, and content per cubic centimeter of K2CO3 can be as high as 0.466 g.

A Comparative Study on Johnson Cook, Modified Zerilli-Armstrong, and Arrhenius-Type Constitutive Models to Predict Compression Flow Behavior of SnSbCu Alloy.

The flow behavior of the SnSbCu alloy is studied experimentally by the compression tests in the range of the strain rates from 0.0001 to 0.1 s-1 and temperature from 293 to 413 K. Based on the experimental data, three constitutive models including the Johnson-Cook (J-C), modified Zerilli-Armstrong (Z-A), and Arrhenius-type (A-type) models are compared to find out an optimum model to describe the flow behavior of the SnSbCu alloy. The results show that the J-C model could predict the flow behavior of the SnSbCu alloy accurately only at some specific strain rates and temperature near the reference values. The modified Z-A and A-type constitutive models can give better fitting results than the J-C model. While, at high strains, the predictive values of the modified Z-A model have larger errors than those at low strains, which means this model has limitations at high strains. By comparison, the A-type model could predict the experimental results accurately at the whole strain range, which indicates that it is a more suitable choice to describe the flow behavior of the SnSbCu alloy in the focused range of strain rates and temperatures. The work is beneficial to solve the tribological problem of the bearing of the marine engine by integrating the accurate constitutive model into the corresponding numerical model.

Effects of Treatment of Treadmill Combined with Electro-Acupuncture on Tibia Bone Mass and Substance PExpression of Rabbits with Sciatic Nerve Injury.

The peripheral nervous system may play an important role in normal bone maintenance and remodeling. Substance P (SP) is a neuropeptide associated with bone loss and formation that may mediate the effects of the nervous system. The purpose of this study is to determine if treadmill running combined with electro-acupuncture at Jiaji acupoints (Jiaji-EA) affects tibial bone mass and SP expression in rabbits with sciatic nerve injury. Twenty-four juvenile male New Zealand white rabbits were randomly assigned to one of 4 groups: sham injury control (sham), sciatic never crush control (SNCr), treadmill running (treadmill), and Jiaji-EA combined with treadmill running (ET group). The SNCr, treadmill, and ET groups all had an induced sciatic never crush injury of approximately 2mm. Control groups received no intervention; the treadmill and ET groups were trained by treadmill; the ET group also received Jiaji-EA. After the 4 weeks of treatment, toe-spreading index (TSI), BMD, bone strength, and SP expression in the tibia were significantly lower in the nerve injury groups (SNCr, treadmill, and ET) compared to the sham groups (p<0.05). Treatment (treadmill and ET groups) increased all measures compared to the SNCr group (p<0.05). Further, TSI, BMD, bone strength, and SP expression in the ET group were higher than the treadmill group (p<0.05). Our results indicate that treadmill therapy combined with electro-acupuncture at Jiaji acupoints prevents bone loss in rabbit tibias after sciatic nerve injury. This may occur in two ways: indirectly in association with axon regeneration and directly via loading on the bone mediated through increased SP expression. This study provides important evidence for the clinical treatment of bone loss after peripheral nerve injury.

The effects of different tensile parameters for the neurodynamic mobilization technique on tricipital muscle wet weight and MuRf-1 expression in rabbits with sciatic nerve injury.

BACKGROUND: After peripheral nerve injury, muscles without innervation begin to undergo atrophy. Research has suggested that MuRf-1 may play a role in muscle atrophy. The neurodynamic mobilization technique (NMT) is a manual therapy method used to elongate a nerve along its long axis, resulting in improved blood flow to the nerve. However, the nerve can be damaged if elongated too much. The purpose of this study is to observe the effect of NMT on muscle wet weight and MuRf-1 expression in rabbits with sciatic nerve injury. METHODS: Six adult rabbits were measured to determine the relationship between the joint angle of the lower limb and percent of sciatic nerve elongation to define the tensile parameters of NMT; Thirty adult rabbits were randomly assigned into a sham, model, NMT-A, NMT-B, or NMT-C groups. Four weeks post-treatment, the wet mass of the tricipital muscles and MuRf-1 expression were observed. RESULTS: The wet mass of the tricipital muscles in the NMT-B group was significantly greater than the NMT-A, NMT-C, and model groups. In addition, MuRf-1 expression was significantly reduced in the NMT-B group compared with the NMT-A, NMT-C, and model groups. CONCLUSIONS: Elongating the nerve by NMT of 9% in rabbits decreased MuRf-1 expression and decelerated muscle atrophy in the subjects with sciatic nerve injury.

Patient Active Time During Therapy Sessions in Postacute Rehabilitation: Development and Validation of a New Measure.

BACKGROUND AND PURPOSE: The accurate measurement of therapy intensity in postacute rehabilitation is important for research to improve outcomes in this setting. We developed and validated a measure of Patient Active Time during physical (PT) and occupational therapy (OT) sessions, as a proxy for therapy intensity. METHODS: This measurement validity study was carried out with 26 older adults admitted to a skilled nursing facility (SNF) for postacute rehabilitation with a variety of main underlying diagnoses, including hip fracture, cardiovascular diseases, stroke, and others. They were participants in a randomized controlled trial that compared an experimental high-intensity therapy to standard-of-care therapy. Patient Active Time was observed by research raters as the total number of minutes that a patient was actively engaging in therapeutic activities during PT and OT sessions. This was compared to patient movement (actigraphy) quantified during some of the same PT/OT sessions using data from three-dimensional accelerometers worn on the patient's extremities. RESULTS: Activity measures were collected for 136 therapy sessions. Patient Active Time had high interrater reliability in both PT (r = 0.995, p < 0.001) and OT (r = 0.95, p = 0.012). Active time was significantly correlated with actigraphy in both PT (r = 0.73, p < 0.001) and OT (r = 0.60, p < 0.001) and discriminated between a high-intensity experimental condition and standard of care rehabilitation: in PT, 47.0 ± 13.5 min versus 16.7 ± 10.1 min (p < 0.001) and in OT, 46.2 ± 15.2 versus 27.7 ± 6.6 min (p < 0.001). CONCLUSIONS: Systematic observation of Patient Active Time provides an objective, reliable, and valid index of physical activity during PT and OT treatment sessions that has utility as a real-world alternative to the measurement of treatment intensity. This measure could be used to differentiate higher from lower therapy treatment intensity and to help determine the optimal level of active therapy time for patients in postacute and other settings.

Experimental and computational analysis of composite ankle-foot orthosis.

Carbon fiber (CF) ankle-foot orthoses (AFOs) can improve gait by increasing ankle plantar-flexor power and improving plantar-flexor ankle joint moment and energy efficiency compared with posterior leaf spring AFOs made of thermoplastic. However, fabricating a CF AFO to optimize the performance of the individual user may require multiple AFOs and expensive fabrication costs. Finite element analysis (FEA) models were developed to predict the mechanical behavior of AFOs in this study. Three AFOs, two made of CF composite material and one made of thermoplastic material, were fabricated and then mechanically tested to produce force-displacement data. The FEA models were validated by comparing model predictions with mechanical testing data performed under the same loading and boundary conditions. The actual mechanical testing demonstrated that CF performs better than thermoplastic. The simulation results showed that FEA models produced accurate predictions for both types of orthoses. The relative error of the energy return ratio predicted by the CF AFO FEA model developed in this study is less than 3%. We conclude that highly accurate FEA models will allow orthotists to improve CF AFO fabrication without wasting resources (time and money) on trial and error fabrications that are expensive and do not consistently improve AFO and user performance.

Gender Differences in Modifying Lumbopelvic Motion during Hip Medial Rotation in People with Low Back Pain.

Reducing increased or early lumbopelvic motion during trunk or limb movements may be an important component of low back pain treatment. The ability to reduce lumbopelvic motion may be influenced by gender. The purpose of the current study was to examine the effect of gender on the ability of people with low back pain to reduce lumbopelvic motion during hip medial rotation following physical therapy treatment. Lumbopelvic rotation and hip rotation before the start of lumbopelvic rotation were assessed pre- and posttreatment for 16 females and 15 males. Both men and women decreased lumbopelvic rotation and completed more hip rotation before the start of lumbopelvic rotation post-treatment compared to pre-treatment. Men demonstrated greater lumbopelvic rotation and completed less hip rotation before the start of lumbopelvic rotation than women both pre- and post-treatment. Both men and women reduced lumbopelvic motion relative to their starting values, but, overall, men still demonstrated greater and earlier lumbopelvic motion. These results may have important implications for understanding differences in the evaluation and treatment of men and women with low back pain.

Differences in end-range lumbar flexion during slumped sitting and forward bending between low back pain subgroups and genders.

Patterns of lumbar posture and motion are associated with low back pain (LBP). Research suggests LBP subgroups demonstrate different patterns during common tasks. This study assessed differences in end-range lumbar flexion during two tasks between two LBP subgroups classified according to the Movement System Impairment model. Additionally, the impact of gender differences on subgroup differences was assessed. Kinematic data were collected. Subjects in the Rotation (Rot) and Rotation with Extension (RotExt) LBP subgroups were asked to sit slumped and bend forward from standing. Lumbar end-range flexion was calculated. Subjects reported symptom behaviour during each test. Compared to the RotExt subgroup, the Rot subgroup demonstrated greater end-range lumbar flexion during slumped sitting and a trend towards greater end-range lumbar flexion with forward bending. Compared to females, males demonstrated greater end-range lumbar flexion during slumped sitting and forward bending. A greater proportion of people in the Rot subgroup reported symptoms with each test compared to the RotExt subgroup. Males and females were equally likely to report symptoms with each test. Gender differences were not responsible for LBP subgroup differences. Subgrouping people with LBP provides insight into differences in lumbar motion within the LBP population. Results suggesting potential consistent differences across flexion-related tasks support the presence of stereotypical movement patterns that are related to LBP.

Clinical examination procedures to determine the effect of axial decompression on low back pain symptoms in people with chronic low back pain.

STUDY DESIGN: Observational. OBJECTIVE: To assess the effects of spinal decompression procedures performed during a clinical exam on low back pain (LBP) symptoms. BACKGROUND: Not all patients report an immediate or complete improvement in symptoms when the direction of lumbar motion or alignment is corrected according to principles of the movement system impairment (MSI) model. Axial compression of the spine may be responsible for the remaining symptoms. METHODS: Seventy subjects (mean ± SD age, 41.9 ± 11.5 years; 38 females, 32 males) with chronic LBP were evaluated using a standardized MSI exam. Seven tests assessing the effects of spinal decompression on LBP were added to the exam if the subjects' symptoms were not alleviated with typical standardized corrections of movement and alignment. For each test of decompression, subjects reported their symptoms compared to a reference movement or position. RESULTS: When decompression was performed during lateral bending to the right and left, 21 of 21 (100%) and 16 of 20 (80%) subjects, respectively, reported an improvement. When traction was applied to subjects in right and left sidelying, 6 of 11 (55%) and 7 of 9 (78%), respectively, reported an improvement. When patients performed a push-up in sitting, 36 of 51 (71%) reported an improvement. In subjects who had symptoms in unsupported sitting, 41 of 57 (72%) reported an improvement in supported sitting. In subjects who reported symptoms in standing, 33 of 47 (70%) reported an improvement in hook-lying. CONCLUSION: Patients with chronic LBP consistently reported an improvement in symptoms with tests proposed to decrease the axial load on the spine. These tests are a quick and effective way to assess the contribution of axial decompression to LBP symptoms and potentially could be used as part of the plan of care.

Sex differences in lumbopelvic movement patterns during hip medial rotation in people with chronic low back pain.

OBJECTIVE: To examine sex differences in lumbopelvic motion and symptom behavior during hip medial rotation in people with low back pain (LBP). We hypothesized that men would demonstrate greater and earlier lumbopelvic motion and would be more likely to report increased symptoms compared with women. DESIGN: Cross-sectional observational study. SETTING: University musculoskeletal analysis laboratory. PARTICIPANTS: Persons with chronic LBP (N=59; 30 men, 29 women) were recruited from the community and a university-based physical therapy clinic. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Lumbopelvic rotation range of motion, amount of hip rotation completed before the start of lumbopelvic motion, and provocation of LBP symptoms during the test of prone hip medial rotation were measured. RESULTS: Men demonstrated significantly more lumbopelvic rotation (men, 10.0°±5.1°; women, 4.5°±3.9°; P<.001) and completed less hip rotation before the start of lumbopelvic motion (men, 5.4°±3.8°; women, 16.0°±13.2°; P<.001) compared with women. Additionally, a significantly greater percentage of men (60.0%) than women (34.5%; P=.050) reported increased symptoms with hip medial rotation. CONCLUSIONS: Men could be at greater risk than women for experiencing LBP symptoms related to hip medial rotation as a result of greater and earlier lumbopelvic motion.

Effect of classification-specific treatment on lumbopelvic motion during hip rotation in people with low back pain.

Increased and early lumbopelvic motion during trunk and limb movements is thought to contribute to low back pain (LBP). Therefore, reducing lumbopelvic motion could be an important component of physical therapy treatment. Our purpose was to examine the effects of classification-specific physical therapy treatment (Specific) based on the Movement System Impairment (MSI) model and non-specific treatment (Non-Specific) on lumbopelvic movement patterns during hip rotation in people with chronic LBP. We hypothesized that following treatment people in the Specific group would display decreased lumbopelvic rotation and achieve more hip rotation before lumbopelvic rotation began. We hypothesized that people in the Non-Specific group would display no change in these variables. Kinematic data collected before and after treatment for hip lateral and medial rotation in prone were analyzed. The Specific group (N = 16) demonstrated significantly decreased lumbopelvic rotation and achieved greater hip rotation before the onset of lumbopelvic rotation after treatment with both hip lateral and medial rotation. The Non-Specific group (N = 16) demonstrated significantly increased lumbopelvic rotation and no change in hip rotation achieved before the onset of lumbopelvic rotation. People who received treatment specific to their MSI LBP classification displayed decreased and later lumbopelvic motion with hip rotation, whereas people who received generalized non-specific treatment did not.

Plantar stresses on the neuropathic foot during barefoot walking.

BACKGROUND AND PURPOSE: Patients with diabetes mellitus and peripheral neuropathy are at high risk for plantar skin breakdown due to unnoticed plantar stresses during walking. The purpose of this study was to determine differences in stress variables (peak plantar pressure, peak pressure gradient, peak maximal subsurface shear stress, and depth of peak maximal subsurface shear stress) between the forefoot (where most ulcers occur) and the rear foot in subjects with and without diabetes mellitus, peripheral neuropathy, and a plantar ulcer measured during barefoot walking. SUBJECTS: Twenty-four subjects participated: 12 with diabetes mellitus, peripheral neuropathy, and a plantar ulcer (DM+PN group) and 12 with no history of diabetes mellitus or peripheral neuropathy (control group). The subjects (11 men, 13 women) had a mean age (+/-SD) of 54+/-8 years. METHODS: Plantar pressures were measured during barefoot walking using a pressure platform. Stress variables were estimated at the forefoot and the rear foot for all subjects. RESULTS: All stress variables were higher (127%-871%) in the forefoot than in the rear foot, and the peak pressure gradient showed the greatest difference (538%-871%). All stress variables were higher in the forefoot in the DM+PN group compared with the control group (34%-85%), and the peak pressure gradient showed the greatest difference (85%). The depth (X+/-SD) of peak maximum subsurface shear stress in the forefoot in the DM+PN group was half that in the control group (3.8+/-2.0 versus 8.0+/-4.3 mm, respectively). DISCUSSION AND CONCLUSION: : These results indicate that stresses are relatively higher and located closer to the skin surface in locations where skin breakdown is most likely to occur. These stress variables may have additional value in predicting skin injury over the traditionally measured peak plantar pressure, but prospective studies using these variables to predict ulcer risk are needed to test this hypothesis.

Pressure gradient and subsurface shear stress on the neuropathic forefoot.

BACKGROUND: Stresses within the neuropathic foot's tissues can be estimated by pressure distributions and may provide information regarding the potential for skin breakdown. The purposes of this study were to: (1) determine the magnitude of peak plantar pressure, pressure time integral, peak pressure gradient, and peak maximum shear stress; and (2) determine the association of these variables with one another. METHODS: Forefoot peak plantar pressure, pressure time integral, peak pressure gradient, peak maximal shear stress, and depth of peak maximal shear stress were calculated for 16 controls, 16 people with diabetic neuropathy, and 22 people with diabetic neuropathy and a history of ulceration from pressure assessments. FINDINGS: Peak plantar pressure, pressure gradient, and maximal shear stress were greater in subjects with a history of ulceration relative to control subjects (P<0.03), pressure gradient was greater in subjects with diabetic neuropathy and a history of ulceration compared to subjects with diabetic neuropathy and no history of ulceration (P<0.02), and depth of maximal shear stress was less in both groups of subjects with diabetic neuropathy compared to controls (P<0.03). Strong relationships existed between the variables. INTERPRETATION: Although these variables are associated with one another, peak pressure gradient and peak maximal shear stress provide information concerning plantar pressure distribution and the potentially injurious internal stresses within the foot's soft tissues. Peak pressure gradient and peak maximal shear stress may perhaps be more discriminating than peak plantar pressure alone in distinguishing between groups of individuals who are at risk for developing a foot ulcer.

Effect of peak pressure and pressure gradient on subsurface shear stresses in the neuropathic foot.

The pressure distribution on the plantar surface of the foot may provide insights into the stresses within the subsurface tissues of patients with diabetes mellitus and peripheral neuropathy (PN) who are at risk for skin breakdown. The purposes of this study were to (1) estimate the stress distribution in the subsurface soft tissue from a measured surface pressure distribution and determine any differences between values in the forefoot and rearfoot, and (2) determine the relationship between maximum shear stress (MSS) (magnitude and depth) and characteristics of the pressure distribution. The measured in-shoe pressure distributions during walking characterized by the peak plantar pressure and maximum pressure gradient on the plantar surface of the feet for 20 subjects with diabetes, PN and history of a mid foot or forefoot plantar ulcer were analyzed. The effects of peak pressure and maximum pressure gradient at the peak pressure location on the stress components in the subsurface soft tissue were studied using a potential function method to estimate the subsurface tissue stress. The calculated MSSs are larger in magnitude and located closer to the surface in the forefoot, where most skin breakdown occurs, compared to the rearfoot. In addition, the MSS (magnitude and depth) is highly correlated with the pressure gradient (r=-0.77 & 0.61) and the peak pressure (r=-0.61 & 0.91). The peak pressure and the maximum pressure gradient obtained from the surface pressure distribution appear to be important variables to identify where MSSs are located in the subsurface tissues on the plantar foot that may lead to skin break down.

"Pressure gradient" as an indicator of plantar skin injury.

OBJECTIVE: Peak plantar pressures (PPPs) have been studied extensively as a contributing factor to skin breakdown, especially in the forefoot where most plantar neuropathic ulcers occur. The purposes of this article were to 1) describe an additional pressure variable, the peak pressure gradient (PPG), 2) determine whether the PPG is higher in the forefoot than in the rearfoot (even when compared with PPP), and 3) determine the correlation between the PPG and PPP at the forefoot and rearfoot in subjects with diabetes, peripheral neuropathy, and a history of plantar ulcer. RESEARCH DESIGN AND METHODS: Twenty subjects (12 male and 8 female) with diabetes, peripheral neuropathy, and a mean +/- SD age of 57 +/- 9 years participated. Plantar pressures were collected during walking in footwear. The PPP and the PPG (defined as the spatial change in plantar pressure across adjacent sites of the foot surface around the PPP) were determined for the forefoot and rearfoot, and the forefoot-to-rearfoot ratios for each variable were calculated. RESULTS: The mean PPG was 143% higher in the forefoot than in the rearfoot, whereas the mean PPP was only 36% higher in the forefoot than in the rearfoot (P < 0.0001). The PPG forefoot-to-rearfoot ratio (2.84 +/- 1.36) was nearly two times greater than the PPP forefoot-to-rearfoot ratio (1.48 +/- 0.58) (P < 0.0001). The correlation between PPP and PPG was r = 0.59 at the forefoot and r = 0.75 at the rearfoot. CONCLUSIONS: The PPG was substantially higher in the forefoot than in the rearfoot even when compared with the PPP. The PPG appears to be providing additional information about the stresses experienced by the soft tissues of the foot, especially in the forefoot. The PPG may be a useful indicator of skin trauma because spatial changes in high plantar pressures may identify high stress concentrations within the soft tissue.

Plantar tissue stiffness in patients with diabetes mellitus and peripheral neuropathy.

OBJECTIVE: To determine if a difference exists in the plantar soft tissue of patients with diabetes mellitus (DM) and peripheral neuropathy (PN) compared with age-matched controls. DESIGN: Case-control study with a parallel 3-element 1-dimensional viscoelastic model developed to characterize indentation data. SETTING: Data collection performed in an academic physical therapy laboratory. PARTICIPANTS: Forty subjects were recruited into 2 groups (20 subjects with DM, PN, and history of plantar ulcers; 20 control subjects), matched for age (DM: 55.22+/-9.39 y; control: 55.91+/-10.97 y), gender (DM: 14 men, 6 women; control: 14 men, 6 women), and body mass index (DM: 32.96+/-8.39 kg/m(2); control: 32.58+/-7.69 kg/m(2)). INTERVENTIONS: The plantar soft tissue stiffness was measured over the first, third, and fifth metatarsals, and heel of each subject using an indentor system that accurately measures force/displacement (F/D) data. A parallel 3-element viscoelastic mechanical model was then used to transform the F/D data into values that were used to make stiffness assessments. MAIN OUTCOME MEASURE: The element coefficients of our model indicated the stiffness of the plantar tissue. RESULTS: The plantar tissue of the subjects with DM over the metatarsal heads was stiffer than the control population as indicated by one of the spring constants in the parallel 3-element model (first: 1.13+/-0.55 N/mm vs.72+/-.32 N/mm; third:.96+/-.32 N/mm vs.79+/-.17 N/mm; fifth:.90+/-.31 N/mm vs.69+/-.28 N/mm; P<.05). CONCLUSIONS: The plantar tissue of subjects with DM, PN, and a history of ulcers was stiffer than control subjects. However, additional research is needed to determine the relationship among increased soft tissue stiffness, plantar pressures, and skin breakdown.