Capacity Test Research Articles

Bicyclic guanidine superbase carboxylate salts for cellulose dissolution.

Bicyclic guanidines are utilized in organic synthesis as base catalysts or reagents. They also offer a platform for coordination chemistry, for example in CO2 activation, and their carboxylate salts offer an efficient media for cellulose dissolution. We have studied a series of bicyclic guanidines with varying ring sizes and with varying methyl substituents with a specific aim to find hydrolytically stable acetate salts for dissolution and processing of cellulose. Different superbase synthesis pathways were tested, followed by hydrolytic stability and cellulose dissolution capacity tests. The synthesis pathways were designed to enable the scale up of the production of the superbases considering the availability of the starting molecules and the feasibility of the synthesis. As a result, we found several hydrolytically stable bicyclic guanidine structures, which can overcome many of the reoccurring problems as carboxylate salts or free bases.

Effects of physical training on the metabolic profile of rats exposed to chronic restraint stress

IntroductionDespite strong evidences supporting the protective role of exercise against stress-induced repercussions, the literature remains inconclusive regarding metabolic aspects. Therefore, this study aimed to evaluate the effect of Physical Training (PT) by swimming on the metabolic parameters of rats subjected to restraint stress. MethodsWistar rats (n = 40) were divided into four groups: Control (C), Trained (T), Stressed (S), and Trained/Stressed (TS). The restraint stress protocol involved confining the animals in PVC pipes for 60 minutes/day for 12 weeks. Concurrently, the swimming PT protocol was performed without additional load in entailed sessions of 60 minutes conducted five days a week for the same duration. The following parameters were analyzed: fitness progression assessed by the physical capacity test, body mass, serum level of glucose, triglyceride, cholesterol and corticosterone, as well as glycemic tolerance test, evaluated after glucose administration (2 g/kg, i.p.). ResultsTrained groups (T and TS) exhibited enhanced physical capacity (169 ± 21 and 162 ± 22% increase, respectively) compared to untrained groups (C: 9 ± 5 and S: 11 ± 13% increase). Corticosterone levels were significantly higher in the S group (335 ± 9 nmoL/L) compared to C (141 ± 3 nmoL/L), T (174 ± 3 nmoL/L) and TS (231 ± 7 nmoL/L), which did not differ from each other. There were no significant changes in serum glucose, cholesterol, and triglyceride levels among the groups. However, the glycemic curve after glucose loading revealed increased glycemia in the S group (area under curve 913 ± 30 AU) but the TS group exhibited values (673 ± 12 AU) similar to the groups C (644 ± 10 AU) and T (649 ± 9 AU). ConclusionSwimming-based training attenuated stress-induced corticosterone release and prevented glucose intolerance in rats, reinforcing the importance of exercise as a potential strategy to mitigate the pathophysiological effects of stress.

The influence of a physiotherapeutic intervention program for patients with post-COVID-19 syndrome: a quasi-experimental study

Post-COVID-19 syndrome affects patients regardless of the severity of the disease. The most common symptoms are fatigue, migraine, attention deficit, dyspnea, and depression. Physiotherapeutic intervention has been used as a strategy to aid the rehabilitation of patients. Objective: To analyze the effects of a physiotherapeutic rehabilitation program on quality of life, functional capacity, perceived exertion, perception of pain, and muscle strength in patients with post-COVID-19 syndrome. Methods: This is a quasi-experimental study with 33 participants, divided into two groups: an intervention group (IG) who received the physiotherapeutic rehabilitation program and a control group (CG) who did not. Participants were assessed for strength before and after the intervention period, using handgrip dynamometry and being assessed with a visual analog scale (VAS) for pain, the six-minute walk test (6MWT) for functional capacity, the BORG scale for exertion perception, and the SF-36 scale for quality of life. Results: A significant increase (p<0.05) in quality of life was observed in the IG in the SF-36 domains of physical functioning, physical role limitations, bodily pain, and increased handgrip strength. There was a significant difference (p<0.05) between the groups for perceived exertion before and after the intervention. No significant differences were found among the other variables. Conclusion: The physiotherapeutic intervention program improved the quality of life assessed with the SF-36 domains of physical functioning, physical role limitations, and bodily pain, and increased handgrip strength of patients with symptoms of post-COVID-19 syndrome.

Effects of Buteyko Breathing Technique versus Diaphragmatic Breathing on Exercise Capacity and Quality of Life in Patients with Chronic Obstructive Pulmonary Disease

Background: Chronic Obstructive Pulmonary Disease (COPD) is a prevalent condition characterized by decreased respiratory function and reduced quality of life. Pulmonary rehabilitation techniques, specifically Buteyko Breathing Technique (BBT) and Diaphragmatic Breathing Technique (DBT), have been suggested to improve these aspects in COPD patients. However, comparative efficacy of these techniques remains uncertain. Objective: This study aimed to compare the effectiveness of BBT and DBT on exercise capacity and quality of life in patients with COPD. Methods: In a randomized clinical trial (WHO Registry of IRCTs: NCT05947227), 48 COPD patients (aged 40-65 years) were enrolled and randomly assigned to either BBT or DBT groups. Both groups underwent respective breathing technique training as part of pulmonary rehabilitation over a 10-month period at Jinnah Hospital, Lahore. Key measurements included the 6-minute walk test (6MWT) for exercise capacity and the St. George Respiratory Questionnaire (SGRQ) for quality of life assessment. The Modified Borg Dyspnea Scale was used to categorize dyspnea severity. Data were analyzed using SPSS software (Version 25), with parametric and non-parametric tests applied for comparative analysis. Results: Both groups showed improvement post-intervention, but DBT demonstrated superior outcomes. Quality of life scores improved from an average of 85.33 (SD=1.110) to 76.06 (SD=4.503) in the DBT group, compared to 87.16 (SD=4.55) to 83.10 (SD=5.76) in the BBT group (p=0.000). Similarly, 6MWT distances showed significant improvement in the DBT group. The DBT group also exhibited a more considerable enhancement in activity scores and dyspnea reduction compared to the BBT group. Conclusion: While both BBT and DBT are effective in improving exercise capacity and quality of life in COPD patients, DBT shows a more significant improvement. These findings suggest that DBT could be a more favorable technique in pulmonary rehabilitation for COPD patients.

Effects of virtual reality-based pulmonary rehabilitation in patients with chronic obstructive pulmonary disease: A meta-analysis.

Virtual reality (VR)-based pulmonary rehabilitation has been used in the management of chronic obstructive pulmonary disease (COPD). The efficacy of VR-based pulmonary rehabilitation for improving lung function in patients with COPD is controversial. Therefore, the aim of this meta-analysis was to evaluate the efficacy of VR combined with pulmonary rehabilitation for lung function in patients with COPD. This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The search was performed in the Cochrane Library, EMBASE, Web of Science, PubMed, and China National Knowledge Infrastructure databases from inception to February 1, 2023. All included studies were randomized controlled trials that assessed VR combined with pulmonary rehabilitation for COPD patients. The effect size was calculated with standardized mean difference (SMD) and its 95% confidence interval (CI). The Cochrane Collaboration tool was used to assess the risk of bias. Publication bias was assessed by Egger test. A total of 11 studies met the inclusion criteria and were included in this study. The combined effect size showed that VR combined with pulmonary rehabilitation was more effective than pulmonary rehabilitation alone at improving forced expiratory volume in 1 second% (SMD: 0.51; 95% CI 0.19,0.82; P = .002), forced expiratory volume in 1 second/forced vital capacity (SMD: 0.71; 95% CI 0.49,0.93; P < .001), dyspnea (SMD: -0.44; 95% CI -0.66, -0.22; P < .001), and 6-minute walking test (SMD: 059; 95% CI 0.39, 0.79; P < .001). In addition, the VR combined with pulmonary rehabilitation improved depression (SMD: -0.34; 95% CI -0.05, -0.03; P = .033) and anxiety mood (SMD: -0.57; 95% CI -1.11, -0.04; P = .036) compared with the pulmonary rehabilitation group. This meta-analysis indicated that VR regimens could be used to enhance the therapeutic effect of pulmonary rehabilitation in patients with COPD. However, as a rapidly evolving field, more well-designed randomized controlled trials are needed to determine the impact of VR-based pulmonary rehabilitation on COPD patients.

Association between Cardiopulmonary Exercise Test and severity of obstructive sleep apnea syndrome

Review Association between Cardiopulmonary Exercise Test and Severity of Obstructive Sleep Apnea Syndrome Jianyu Wang 1,2, * , Shishi Zhang 2, Luying Jiang 3, Chunran Zhang 3, and Houjuan Zuo 2 1 Tianyou Hospital, Wuhan University of Science and TechnologyWuhan430064China 2 Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and TechnologyWuhan430030China 3 The 3rd Department of Cardiology, The First Affiliated Hospital of The Medical College, Shihezi UniversityShihezi832008China * Correspondence: Wangjianyu1003@163.com Received: 17 April 2023 Accepted: 6 June 2023 Published: 27 December 2023 Abstract: Obstructive sleep apnea syndrome (OSAS) is becoming widespread, especially in people with obesity. As it is usually measured by polysomnography (PSG), the role of cardiopulmonary exercise test (CPET), a new exercise capacity test, has not attracted enough attention in OSAS research. In this article, we explore the relationship between CPET results and patients with OSAS. 68 individuals were recruited and divided into three groups: negative/mild group (n = 22, apnea hypopnea index (AHI) &lt; 15), moderate group (n = 22, 15 ≤ AHI &lt; 30) and severe group (n = 24, AHI ≥ 30). Clinical parameters, cardiopulmonary exercise test (CPET) indexes, and apnea hypopnea index (AHI) were compared among the three groups. A multivariate analysis was carried out to assess which factors determine the index of AHI. The ANOVA analyses were used to evaluate the difference among the three groups. Receiver operating characteristic analyses were chosen to detect the prediction efficiency of the CPET index for AHI. The predictive power of using the CPET index (VO2/kg peak) combined with the body mass index (BMI) of patients in the detection of AHI was significantly better when compared with using the CPET index only. There was a notable correlation between VO2 and the index of AHI (r = 0.249, P = 0.04). Also, the CPET data (VO2/kg peak) combined with the BMI of patients has powerful predictive value for the severity of OSAS in patients. It is expected to be a promising way to predict the severity of OSAS in the future. Our study provides a new strategy for predicting whether a patient is in the early phase OSAS.

Establishment and application of propped hydraulic fracture conductivity theoretical model based on fracturing efficiency index

Hydraulic fracturing technology is a key technology for the development of unconventional oil and gas reservoirs, and the conductivity of hydraulic fractures has a great impact on their production. The paper introduces the "fracturing efficiency index" as means of characterising the dynamic relationship between hydraulic fracture expansion and proppant filling. It also suggests a way to figure out the proppant fracture inflow capacity. This approach addresses issues such as uneven fracturing fluid dosage, a wide range of injection discharges, and inconsistent sand spreading concentration encountered during fracturing operations. Based on this model, the influencing factors of the flow-conducting capacity such as proppant particle size, sand spreading concentration, liquid injection displacement, and proppant crushing rate, were analyzed, and the calculated results of this model are closer to the experimental results of the API flow-conducting capacity test compared with the calculated results of the reference model. Finally, this model was used to optimize the fluid volume, sand volume, and displacement of hydraulic fracturing in the Jiping 1H shale gas field. The research results show that: (1) the fracturing efficiency index is negatively correlated with the conductivity of hydraulic fractures, whereas is positively correlated with the enhancement of conductivity; (2) our model is applicable to the calculation of supported fracture inflow capacity for high sand concentration, large particle size, intermediate fracture flow and low crushing rate, and the results are close to more than 98.58%, 98.29%, 95.68% and 95.08% of the experimental results, respectively; (3) On-site hydraulic fracturing does not result in higher production capacity with more fracturing fluid dosage, higher displacement and more sand addition; there are optimal fluid, optimal displacement and optimal sand intervals, which are optimized to increase production by 26.92%. It can be seen that the hydraulic fracture conductivity model can optimize various parameters of on-site fracturing construction.

Probabilistic analysis of seasonal influence on the prediction of pile bearing capacity by CPT: A case study

In this study, we used a probabilistic approach to evaluate the probability of failure of small diameter bored piles in unsaturated sandy soils. The prediction of the bearing capacity was based on the Cone Penetration Test (CPT). We assessed the seasonal influence by analyzing CPT data from dry and wet seasons. The LCPC and Aoki-Velloso semiempirical methods were deterministically applied, and the Aoki-Velloso method was examined using reliability theory. The first-order reliability method (FORM) was used to evaluate the probability of failure and calculate the reliability index based on random variables obtained from CPT data considering the effect of season when predicting bearing capacity. A total of 8.0 m long bored piles with diameters of 0.25, 0.30, and 0.35 m were used for both deterministic and probabilistic analyses. We also evaluated the influence of load ratio variation on the reliability index and determined the pile length required to reach a target reliability index value. Reliability analyses considering CPT campaigns conducted in different seasons showed the effect of season on the prediction of bearing capacity. For example, an 8.0 m long pile with a 0.30 m diameter and 100 kN vertical load had a probability of failure of 38.7 % in the wet season and 0.01 % in the dry season. The reliability analyses provided insights into the influence of seasonal variability on in situ tests for pile bearing capacity, affecting the design of foundation elements.

Study on stability of H-type section aluminum alloy perforated members under axial compression and eccentric compression around weak axis

Aluminum alloy components have the advantages of light weight, high strength, favorable machinability, and good acid corrosion resistance, which can greatly reduce maintenance costs and easy to make the structures with beautiful appearance. Based on the shortcomings of existing research fields, the stability of H-type section 6082-T6 aluminum alloy perforated members under axial compression and eccentric compression around weak axis is studied by combining experimental and numerical simulation methods in this paper. The test results of aluminum alloy members under axial compression and aluminum alloy members under eccentric compression around weak axis with different web opening numbers, opening diameters, slenderness ratios and eccentric distances are analyzed. The verified finite element model is used to carry out the extensive parameter analysis focusing on the key variables. Based on the test and numerical simulation results of the stability bearing capacity of 134 members, the design methods for H-type section aluminum alloy perforated members under axial compression and eccentric compression are proposed and evaluated by reference to the existing specification.

Electrospun Sulfonated Silica/P(VDF-TrFE)-Based Composite Membranes for PEM Fuel Cells

Nafion® membranes are the most widely used commercially available membranes for PEM fuel cells due to their good chemical and mechanical stability as well as high ionic conductivity at fully humidified conditions. However, their high cost and inadequate conductivity at lower humidity levels can be addressed as the main drawbacks of Nafion® membranes which needs to be overcome. In this regard new strategies such as complete replacement of these membranes with alternative cost-effective membranes or modifying their properties via synthesizing of Nafion® containing composite membranes by incorporation of some inorganic additives such as silica were extensively investigated previously [1].In this study, we developed two types of electrospun composite membranes: in the first route: membranes were prepared with using P(VDF-TrFE) or PVDF as carrier polymers which are decorated with sulfonated silica (S-SiO2) nanoparticles, as a proton conducting additive. Here S-SiO2 nanoparticles were synthesized via hydrothermal method, then these nanoparticles were added to the electrospinning solutions to prepare the hybrid membranes. The effect of S-SiO2 amount in final properties of these membranes were investigated via preparing samples with three different S-SiO2/ carrier polymer ratios [2]. In the second approach, a combination of sol-gel and dual electrospinning methods were employed to fabricate proton conducting membranes comprising sulfonated silica network, Nafion®, and PVDF or P(VDF-TrFE) as the carrier polymers. For this purpose, the obtained S-SiO2 network via sol-gel method was incorporated into the Nafion®/carrier polymer mixed fibrous-mats during dual electrospinning process [3]. In both approaches after electrospinning all electrospun mats were transformed to compact membranes via hot-pressing process. Then fabricated mats and compact membranes, were characterized by various techniques including FTIR, XPS, SEM, TEM, ionic conductivity, ion exchange capacity (IEC), water uptake and mechanical tests. Finally, membrane-electrode-assemblies (MEAs) were prepared via composite electrospun membranes and fuel cell performance tests were performed. The results showed an enhancement in ionic conductivity for both set of membranes (102 and 132 mS/cm) compared to commercial Nafion® membranes at the same conditions. Moreover, the fuel cell test exhibited that presence of sulfonated silica in the composite membranes improved the performance at lower humidity conditions (344 mW/cm2 at 60% RH) due to enhanced water retention ability of the resultant composite membranes.

Novel, in situ, electrochemical methodology for determining lead-acid battery positive active material decay during life cycle testing

Understanding the thermodynamic and kinetic aspects of lead-acid battery structural and electrochemical changes during cycling through in-situ techniques is of the utmost importance for increasing the performance and life of these batteries in real-world applications. Here, we describe the application of Incremental Capacity Analysis and Differential Voltage techniques, which are used frequently in the field of lithium-ion batteries, to lead-acid battery chemistries for the first time. These analyses permit structural data to be retrieved from simple electrical tests that infers directly the state of health of the positive active material. We present evidence from full-scale 12 V batteries to demonstrate the techniques and prove their utility to the space. Evaluation of capacity and cycle life testing supports a new theory of Positive Active Material utilization, the Single-Entity/Dual Behaviour-Hypothesis, which is described within our work.

The long-term effects of COVID-19 on pulmonary status and quality of life.

Few studies have looked at how SARS-CoV-2 affects pulmonary function, exercise capacity, and health-related quality of life over time. The purpose of this study was to evaluate these characteristics in post COVID-19 subjects 1 year after recovery. The study included two groups. The case group included post COVID-19 subjects who had recovered after a year, and the control group included healthy participants who had never tested positive for COVID-19. The study screened 90 participants, 42 of whom met the eligibility criteria. The findings revealed that the majority of post COVID-19 subjects had relatively normal lung function 1-year post-recovery. A significant reduction in DLCO (B/P%) was observed in the case group vs. control. The exercise capacity test revealed a clinically significant difference in distance walked and a significant difference in the dyspnea post-walk test in the case group compared to the control group. The case group's health-related quality of life domain scores were significantly affected in terms of energy/fatigue, general health, and physical function. The post COVID-19 subjects were shown to have well-preserved lung function after 1 year. However, some degree of impairment in diffusion capacity, exercise capacity, and health-related quality of life remained.

Estimation of Average and Maximum Daily-Life Mobility Performance Using the Timed Up-and-Go: Exploring the Added Value of an Instrumented Timed Up-and-Go

Introduction: The association between specific motor capacity variables obtained in a laboratory and parameters of daily-life mobility performance (MP) obtained via wearables is still unclear. The Timed Up-and-Go (TUG) test is a widely used motor capacity tests available either as traditional hand-stopped TUG or as instrumented TUG (iTUG), providing specific information about its subphases. This study aimed to: (1) estimate the association between the TUG and specific parameters reflecting average and maximum daily-life MP, (2) estimate the benefits of the iTUG in terms of explaining MP in daily life compared to the TUG. Methods: The present study was a cross-sectional analysis using baseline data of 294 older persons (mean age: 76.7 ± 5.3 years). Univariate linear regression analysis was performed to delineate the coefficient of determination between TUG time and participants’ MP. MP variables containing mean cadence (MCA) to represent average performance and the 95th percentile of mean cadence of walks with more than three steps (p95>3stepsMCA) to represent maximum performance. To determine whether the iTUG variables give more information about MP, a stepwise multivariate regression analysis between iTUG variables and the p95>3stepsMCA variable to represent maximum performance was conducted. Results: The univariate regression models revealed associations of the TUG with MCA (adjusted R2 = 0.078, p < 0.001) and p95>3stepsMCA (adjusted R2 = 0.199, p < 0.001). The multivariate stepwise regression models revealed a total explanation of maximum daily-life MP (p95>3stepsMCA) of the TUG (adjusted R2 = 0.199, p < 0.001) versus iTUG (adjusted R2 = 0.278, p < 0.010). Discussion/Conclusion: This study shows that the TUG better reflects maximum daily-life MP than average daily-life MP. Moreover, we demonstrate the added value of the iTUG for a more accurate estimation of daily MP compared to the traditional TUG. The iTUG is recommended to estimate maximum daily-life MP in fall-prone older adults. The study is a step toward a specific assessment paradigm using capacity variables from the iTUG to estimate maximum daily-life MP.

Analysis the Effect of Activated Natural Zeolites for Fe Metal Adsorption

Zeolite, as an adsorbent, can be improved by a chemical activation process. In this study, zeolite was activated using the acid activation method by soaking natural zeolite with HCl and HF, and the activated zeolite was then used to adsorb Fe metal. Zeolite was characterized using SEM and XRD, and the adsorption capacity of the zeolite was analyzed using AAS. The results of SEM analysis show that zeolite after activation has a more significant number of pores than zeolite before activation. The results of XRD analysis show that zeolite that has been activated has a higher content of quartz (SiO2) and clinoptilolite than zeolite that has not been activated. The results of the zeolite adsorption capacity and efficiency test on Fe metal showed that the most excellent adsorption capacity was when the contact time was 60 minutes, with adsorption capacity and adsorption efficiency values of 3.2403 mg/g and 97.21%.

ANTROPOMETRIC INDICATORS, NUTRITIONALSTATUS AND CARDIOMETABOLIC RISK IN SCHOOLCHILDREN WHIT MAPUCHE AND NON. MAPUCHE ETHNIC GROUPS, CHILE

Objectives: To identify, through the association of anthropometric, status nutritional and physical variables, the cardiometabolic risk in Mapuche and non-Mapuche schoolchildren in the Araucanía Region.&#x0D; Material and methods: It is a descriptive, cross-sectional study, using the Kolmogorov-Smirnov, Mann-Whitney U and Kruskal-Wallis H statistical tests. The data were analyzed with the SPSS program, version 22.0 (p &lt; 0.05). The participants were 250 schoolchildren: 185 Mapuche and 65 non-Mapuche. Anthropometric tests of weight and height for age, body mass index (BMI), waist circumference (WC), waist-height ratio (WSR), and the Course Navette aerobic capacity test (VO2max), Ruffier index were evaluated and resting heart rate (RHR).&#x0D; Results: Mapuche and non-Mapuche schoolchildren presented similar sizes; Their weight and waist circumference differed according to their body mass index classifications, however there were no statistically significant differences between the ethnic groups.&#x0D; Conclusions: The size variable does not determine the presence or absence of cardiometabolic risk in schoolchildren with Mapuche and non-Mapuche ethnic ancestry through the WSR indicator. However, the study demonstrated that the weight and WC variables directly influence the presence of cardiometabolic risk in the schoolchildren of the sample diagnosed with overweight and obesity.&#x0D; Keywords: Anthropometry, Schoolchildren, Ethnic group, Cardiometabolic risk.

State of health estimation of second-life batteries through electrochemical impedance spectroscopy and dimensionality reduction

When lithium-ion batteries (LiBs) reach the end of their useful life in electric vehicles (EVs), they can still be used in less demanding applications, a process known as second-life (SL). Nevertheless, to ensure a safe, efficient and reliable operation of the retired LiBs in a SL application, many tests and procedures should be done to determine their internal conditions, and naturally, one of the most important parameters to be determined in these procedures is the state of health (SoH). However, the tests to obtain this parameter are intrusive, requiring taking the LiBs out of service and performing successive discharge and charge cycles in laboratory benches with special equipment, which is costly, have a high energy demand, and is time-consuming. These limitations hinder the SL market since it is estimated that in the next few years, a significant amount of LiBs will be available for SL purposes. This work suggests an approach that employs experimental electrochemical impedance spectroscopy (EIS) data and neural networks (NN) to assess the SoH of lithium-ion cells subjected to SL conditions. Also, a novel approach to perform the dimensionality reduction of the EIS measurements – reducing the time needed to perform the EIS measurement without the loss of significant data – is proposed, where the measurement time can be reduced to 19.10% of its original value, and the number of assets generated by the measurements can be reduced from 81 to 4. The proposed methodology was validated offline using two datasets of lithium-ion cells under SL conditions, the first one considers the EIS data of 395 Lithium Iron Phosphate (LFP) high-capacity cells, and the second one the EIS data of 36 Lithium Nickel Manganese Cobalt (NMC) medium-capacity cells. Root mean square errors of 1.18% and 0.95% in the SoH estimation were obtained for the LFP and NMC cells, respectively. Therefore, the novel methodology that has been proposed in this work offers significant advantages over the conventional capacity test, including non-invasiveness, fast processing time and low energy consumption.

Partial cycling aging of Li-ion batteries in frequency regulation applications

This research analyzes the performance and provides an initial estimation of the health of Lithium-ion (Li-ion) batteries in frequency regulation applications. Frequency regulation applications appear to produce a great strain on batteries as they are constantly cycled as a fast-ramping resource to regulate the frequency in the grid. The frequency regulation battery profile was extracted from data available only from the Pennsylvania–New Jersey–Maryland Interconnection (PJM). Once the battery profile was established, a Li-ion battery was cycled at 25 °C and 40 °C for a duration of 1500 and 4271 partial cycles. The aim was to analyze and compare the performance at 25 °C and 40 °C, and potentially identify the trends that show battery aging and capacity fade. To that end, different methods including capacity tests, throughput, and equivalent full-cycle analysis were performed. Electrochemical Impedance Spectroscopy (EIS) tests were done every 100 or 200 partial cycles to analyze the health and aging of the battery. An Equivalent Circuit Model (ECM) was also developed from EIS test results. One of the objectives was to study how the model parameters changed with the number of cycles and start to identify the main degradation mechanisms associated with the battery operation under frequency regulation. The results of cycling testing and a discussion of the analysis are presented here.

Contraction intensity affects NIRS-derived skeletal muscle oxidative capacity but not its relationships to mitochondrial protein content or aerobic fitness.

To further refine the near-infrared spectroscopy (NIRS)-derived measure of skeletal muscle oxidative capacity in humans, we sought to determine whether the exercise stimulus intensity affected the τ value and/or influenced the magnitude of correlations with in vitro measures of mitochondrial content and in vivo indices of exercise performance. Males (n = 12) and females (n = 12), matched for maximal aerobic fitness per fat-free mass, completed NIRS-derived skeletal muscle oxidative capacity tests for the vastus lateralis following repeated contractions at 40% (τ40) and 100% (τ100) of maximum voluntary contraction, underwent a skeletal muscle biopsy of the same muscle, and performed multiple intermittent isometric knee extension tests to task failure to establish critical torque (CT). The value of τ100 (34.4 ± 7.0 s) was greater than τ40 (24.2 ± 6.9 s, P < 0.001), but the values were correlated (r = 0.688; P < 0.001). The values of τ40 (r = -0.692, P < 0.001) and τ100 (r = -0.488, P = 0.016) correlated with myosin heavy chain I percentage and several markers of mitochondrial content, including COX II protein content in whole muscle (τ40: r = -0.547, P = 0.006; τ100: r = -0.466, P = 0.022), type I pooled fibers (τ40: r = -0.547, P = 0.006; τ100: r = -0.547, P = 0.006), and type II pooled fibers (τ40: r = -0.516, P = 0.009; τ100: r = -0.635, P = 0.001). The value of τ40 (r = -0.702, P < 0.001), but not τ100 (r = -0.378, P = 0.083) correlated with critical torque (CT); however, neither value correlated with W' (τ40: r = 0.071, P = 0.753; τ100: r = 0.054, P = 0.812). Overall, the NIRS method of assessing skeletal muscle oxidative capacity is sensitive to the intensity of skeletal muscle contraction but maintains relationships to whole body fitness, isolated limb critical intensity, and mitochondrial content regardless of intensity.NEW & NOTEWORTHY Skeletal muscle oxidative capacity measured using near-infrared spectroscopy (NIRS) was lower following high-intensity compared with low-intensity isometric knee extension contractions. At both intensities, skeletal muscle oxidative capacity was correlated with protein markers of mitochondrial content (in whole muscle and pooled type I and type II muscle fibers) and critical torque. These findings highlight the importance of standardizing contraction intensity while using the NIRS method with isometric contractions and further demonstrate its validity.

Leaching of heavy metals from tungsten mining tailings: A case study based on static and kinetic leaching tests

Heavy metal (HM) leaching from tungsten mine tailings is a serious environmental risk. In this study, we assess the HM pollution level of tungsten tailings, determine the HM leaching patterns and mechanisms, and estimate the HM fluxes from a tailings reservoir. The results showed that the comprehensive pollution index (CRSi) values that decreased in order of the HM pollution levels in the tailings were cadmium (Cd) > tungsten (W) > lead (Pb) > copper (Cu) = zinc (Zn) > arsenic (As) > manganese (Mn). This result indicated that Cd, W, and Pb were priority pollutants in tailings. The Res fraction of all HMs was greater than 50%. Pb and Cd had similar species fractions with high Exc fractions, and tungsten had a considerable proportion of the Wat fraction. The general acid neutralizing capacity (GANC) test divides the leaching process of HMs into two stages, and each of stage is affected by different mechanisms. A neutral environment promoted tungsten leaching in the column leching test, while an acidic environment promoted Cd and Pb leaching. In addition, the pH effect was more obvious in the early stage. The kinetic fitting results showed that the second-order dynamic model well simulated the leaching of W, Pb, and Cd in most cases. Based on column kinetic leaching test results and tailings parameters, the annual W, Pb, and Cd fluxes were estimated to be 6.35 × 108, 1.3288 × 109, and 1.012 × 108 mg/year, respectively. The above results can guide the environmental management of tungsten tailing reservoirs, such as selecting suitable repair materials and estimating repair service times.

Experimental research and engineering application on bearing capacity of concrete-filled steel tube circular arch

The bearing property and deformation failure law of the CFST circular arch were investigated in order to provide direction for the optimization of the concrete-filled steel tube (CFST) support. The flexural bearing capacity test of the 194 mm × 10 mm CFST was performed initially in this study. It was primarily explored how bearing capacity and deformation of circular arches were affected by the slip of the arch foot and anti-bending strengthening, and the neutral layer migration rule and anti-bending strengthening mechanism of circular arches were examined. The bearing performance of the circular arch under the condition of the concentrated load of the vault and the usual uniform load of the entire span is then simulated in an orthogonal test by numerical simulation in order to extend the experimental investigation. The effect of variables including the steel tube’s outer diameter, thickness, slip of the arch foot, and the ratio of the arch rise to span on the bearing capacity of the circular arch is examined. The study demonstrates that under focused stress on the arch top or full-span normal uniform loading, the arch foot slip is the most important element impacting the CFST support’s bearing capacity. In steel tubes with the same outer diameter and wall thickness, the vector span ratio has a bigger influence than anti-bending strengthening. When the span ratio is the same, the influence of the outer diameter and wall thickness are equal and outweigh the influence of bending strengthening. The circular arch with an outside diameter of 168 mm, a wall thickness of 10 mm, and a rise-span ratio of 0.207 has the best performance characteristics under the influence of concentrated load, and the ultimate failure mechanism is local waist drum deformation failure. Based on the aforementioned study findings, the circular CFST support’s buckling deformation and drum deformation are examined, and a composite support consisting of “anchor net spray + CFST support” is directed for the north three deep track downhill of Yangcheng Coal Mine. Two failure types expose the failure mechanism and provide a technique for optimization. The support had contributed to the circular CFST arc arch’s best bearing performance in the event of waist drum deformation and failure.