Aging Tests Research Articles

(Battery Division Postdoctoral Associate Research Award Sponsored by MTI Corporation and the Jiang Family Foundation) Silicon SEI Instability and its Effect on Calendar Aging

Poor calendar aging has been identified as a major hurdle for commercialization of high-loading silicon anodes. Here, we will discuss a series of efforts identifying and defining the problem of silicon calendar aging and hypotheses for why aging is worse in silicon than in graphite. Some of these hypotheses were tested through a specially designed variable open circuit (OCV) protocol modified from the USABC’s calendar aging protocol to determine contributions from mechanical and chemical degradation. Microcalorimetry and scanning electrochemical microscopy (SECM) were performed to study changes in the solid electrolyte interphase (SEI) on silicon with time. From SECM, the passivation of silicon thin films was found to decrease with increasing time and potential relative to Li/Li+. The overall failure mode of the SEI with time appeared to be global suggesting possible SEI dissolution. X-ray photoelectron spectroscopy supported that there was a loss of SEI species with time. In further support for chemical degradation during calendar aging, when the frequency of reference performance tests (RPTs) was varied, capacity fade was minimally affected. This suggests that time since assembly, rather than cycling, dominated the capacity fade in the calendar aging tests. Microcalorimetry demonstrated changes in heat during the rest as well as after an RPT, highlighting the complexity of silicon aging and setting the stage for our next efforts of in situ quantification of electrolyte degradation products.This research was supported by the U.S. Department of Energy’s Vehicle Technologies Office under the Silicon Consortium Project, directed by Brian Cunningham, and managed by Anthony Burrell. This work was conducted in part by the Alliance for Sustainable Energy, LLC, the manager and operator of the National Renewable Energy Laboratory for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. Sandia National Laboratories is a multimission Laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

(Keynote) on the Challenges and Opportunities for Parameterizing Multi-Physics Battery Models with Expansion Measurements

Lithium-ion batteries are projected to reach cost targets making them competitive with internal combustion engines for light-duty transportation within the decade [1], which will help drive demand for EVs. Upcoming regulations in Europe, China, and the United States for automotive safety and durability will drive the design of battery systems, and the algorithms for battery management over the next decade. The Global Technical Regulation 20 (GTR20) describes the safety requirements for electric vehicle battery systems. In particular, the proposed regulation addresses the need for early detection and warning of occupants about battery faults and failures. The warning should allow for egress 5 minutes prior to the presence of a hazardous situation inside the passenger compartment caused by a battery cell thermal runaway. However, detecting the failure with enough time can be difficult using the current production battery sensor suites. Durability assessment for Lithium-ion batteries is also tricky because these systems are designed to live for more than 10-15 years, so testing under representative conditions could exceed multiple product development cycles. Accelerated aging tests can shorten the testing time to reach the product's end-of-life conditions, typically defined as 70 or 80% state of health, but a deep physical understanding of the degradation modes that are accelerated by the testing is required to project these results back to the real-world use case and warranty period. Due to the many possible definitions of battery State of Health (SoH) which can be related to both capacity loss and internal resistance growth, the Global Technical Regulation 22 (GTR22) defines their durability requirements in terms of two new related metrics: the State of Certified Energy (SOCE) and the State of Certified Range (SOCR). Both metrics represent a percentage of the certified battery energy or electric range remaining at a given point in time. The SOCE is based on the Society of Automotive Engineers (SAE) metric of Usable Battery Energy (UBE). The GTR22 will also require a way for the consumer to read battery health information and usage data from the vehicle. Physics-based battery models which include degradation mechanisms have great promise in addressing many of these challenges due to the relationship between modeled design parameters and the resulting device performance and durability. The models can enable virtual engineering to assess design tradeoffs before building the first prototype, however, parameterizing these models can be difficult due to the large number of parameters. In this presentation, we will explore the challenges of parameterizing physics-based battery models using conventional current, voltage, and temperature measurements. We will show how the measurement of the cell expansion in the laboratory setting and the fixtures that support the testing [2]. The augmentation of expansion data can inform model development and parameterization of a Single Particle Model with electrolyte dynamics (SPMe) implemented in the PyBaMM (Python Battery Mathematical Modelling) framework [3]. Next, we will demonstrate how the sensor data could be paired with the models to augment diagnostic algorithms to infer electrode-level aging phenomena, improve the state of charge estimation, and provide an early warning of gas generation before cell venting. Finally, we will discuss the practical implementation issues in packaging temperature and strain sensors in automotive battery modules and packs. [1] C. Shen, P. Slowik, A. Beach. “INVESTIGATING THE U.S. BATTERY SUPPLY CHAIN AND ITS IMPACT ON ELECTRIC VEHICLE COSTS.” Feb 2024, ICCT REPORT [2] S. Pannala, A. Weng, I. Fischer, J.B. Siegel, and A.G. Stefanopoulou, “Low-cost inductive sensor and fixture kit for measuring battery cell thickness under constant pressure.” 2022, IFAC-PapersOnLine, 55(37), 712-717. [3] Sravan Pannala et al 2024 J. Electrochem. Soc. 171 010532

Study on the corona aging characteristics of KH570-modified nano-Al(OH)₃ cycloaliphatic epoxy resin in hygrothermal environments

Cycloaliphatic epoxy(CE) resin may experience insulation degradation and pose a threat to the safe operation of equipment when used in high-temperature and high-humidity environment. Therefore, to enhance the corona aging resistance of CE under harsh conditions, this study incorporated γ-methacryloxypropyltrimethoxysilane-modified (KH570) nano-Al(OH)₃ with varying content into the CE. The samples were subjected to corona aging tests under different hygrothermal conditions. The corona aging characteristics of CE in high-temperature and high-humidity environments were analyzed using scanning electron microscopy(SEM), Fourier transform infrared spectroscopy(FTIR), resistivity, and dielectric loss measurements before and after modification. The results indicate that as humidity increases, the unmodified samples develop pores and cracks on the surface, which leads to an increased water absorption rate and internal hydrolysis. However, with the increase in filler content, the water absorption channels on the sample surface decrease, effectively suppressing chemical moisture absorption and maintaining the stability of the internal chemical structure. Among the various filler contents, the effect was most pronounced at 3%wtCE. Under 65 % RH conditions, the volume/surface resistivity increased by 27.28 % and 26.9 %, respectively, the leakage current decreased by 64.85 %, while the dry and wet breakdown voltages increased by 9.3 kV and 6.85 kV, respectively, and the dielectric loss variation with humidity was reduced. Compared to the unmodified material, KH570-modified nano-Al(OH)₃ has significantly improved the insulation and aging resistance properties of the material under hot and humid corona aging conditions. This study provides a reference for improving the performance of epoxy resins under high temperature, high humidity, and strong electric field conditions.

Effect of hygrothermal ageing on the mechanical properties of glass fiber reinforced polymer composite: Experimental and numerical approaches

This paper studied the effect of hygrothermal ageing on the mechanical performance of glass fiber-reinforced polymer composites (GFRPCs), a crucial material for marine applications due to its lightweight and superior resistance to environmental chemicals. However, prolonged exposure to moisture and temperature can degrade its properties, impacting structural integrity. The influence of moisture diffusion in GFRP composite laminates was evaluated by accelerated ageing tests, which involved submerging the composite laminate in seawater at 75°C until it reached full saturation. The composite laminates were fabricated with weight fractions of glass fiber reinforcements 55 %, 60 %, and 65 %. After two months of submersion, mechanical characteristics, namely tensile strength, modulus of elasticity, and interlaminar shear strength (ILSS) were investigated. A computational model was developed using COMSOL Multiphysics to analyse the coupled interfaces of moisture diffusion and heat. The failure mechanism of the GFRP composites was analysed using a scanning electron microscope (SEM). After two months of submersion, the moisture uptake data for the tension test samples showed a maximum saturation of 3.45 % for the 55 % fiber weight fraction, leading to a reduction in tensile strength from 269 MPa to 171 MPa and in modulus of elasticity from 24 GPa to 21 GPa. For the ILSS test samples, the maximum moisture saturation was 2.95 % for the 55 % fiber weight fraction, with a corresponding decrease in ILSS from 24 MPa to 21 MPa. However, increasing the glass fiber weight fraction from 55 % to 65 % resulted in improved tensile strength, modulus of elasticity, and ILSS in both as-manufactured and aged samples. The results of simulations and experiments showed that hygrothermal ageing causes the fiber surface to debond and causes matrix cracking, which in turn creates an uneven internal stress field.

Corrosion behaviors of electromagnetic wave absorbing coatings with varying absorber content under combined UV and salt spray exposure

Despite extensive research on the impact of environmental weathering on the degradation of electromagnetic wave absorbing (EWA) coatings, the influence of material composition on their service stability remains underexplored. In this study, we prepared EWA coatings with epoxy resin as the matrix and flaky carbonyl iron (FCI) as the absorber, at concentrations of 50 wt%, 60 wt%, and 70 wt%. These coatings underwent a 192-h combined UV irradiation-salt spray accelerated aging test to examine the effects of varying absorber concentrations on their corrosion behavior and mechanisms. Surface morphology, chemical structure evolution, and corrosion diffusion were analyzed using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) with energy-dispersive X-ray spectroscopy (EDX). Corrosion behaviors and their impact on wave absorption performance were further investigated using electrochemical impedance spectroscopy (EIS) and electromagnetic simulations. Our results show that increasing FCI content accelerates the corrosion rate of the composite coating. This acceleration is attributed to the reduced protective effect of the epoxy matrix at higher FCI concentrations and the defects caused by FCI corrosion, which facilitate the penetration of corrosive media. This study elucidates the influence of varying absorber concentrations on the weather resistance of the coatings and their microscopic mechanisms, providing valuable insights for optimizing the service stability of EWA coatings.

KL‑6, ET‑1 and S100A9 levels in patients with idiopathic pulmonary fibrosis and obstructive sleep apnea.

Obstructive sleep apnea (OSA) and idiopathic pulmonary fibrosis (IPF) frequently coexist. Elevated levels of Krebs von den Lungen-6 (KL-6), endothelin-1 (ET-1) and S100 calcium-binding protein A9 (S100A9) have been observed in patients with IPF, suggesting their potential role as biomarkers for lung fibrosis. The aim of the present study was to measure the levels of KL-6, ET-1 and S100A9 in patients with IPF-OSA and to test the potential of these biomarkers as a characteristic OSA signature with diagnostic and prognostic potential for IPF. A total of 55 subjects with newly-diagnosed IPF participated in the present cross-sectional study. In addition to performing overnight attended polysomnography and pulmonary function tests, serum and bronchoalveolar lavage (BAL) levels of KL-6, along with serum levels of ET-1 and S100A9, were also assessed. A total of 15 patients with IPF and 40 patients with IPF-OSA were included. Age, sex, comorbidities and pulmonary function tests did not differ between the groups. Although there was no significant difference between groups in the levels of KL-6, ET-1 and S100A9 (P>0.05), the serum ET-1 levels tended to be elevated in patients with OSA-IPF compared with patients with IPF (1.78 vs. 1.07 pg/ml; P=0.06). Additionally, a significant association was observed between serum KL-6 levels and the severity of IPF, and also between BAL KL-6 levels and nocturnal mean SaO2 levels, even after taking into account factors such as obesity and smoking. S100A9 levels were associated with the oxygen desaturation index, even after adjustments for obesity, smoking and the gender-age-physiology index, only in the IPF-OSA group. Conclusively, the present findings suggested significant associations between serum ET-1, S100A9 and BAL KL-6 levels and specific OSA severity parameters in the IPF-OSA group. This evidence suggested that these molecules could serve as biomarkers for the identification of patients with IPF-OSA, offering a distinct OSA signature that has diagnostic and potential treatment value. Larger studies are crucial to substantiate the present findings and reinforce this hypothesis.

A Universal Interfacial Reconstruction Strategy Based on Converting Residual Alkali for Sodium Layered Oxide Cathodes: Marvelous Air Stability, Reversible Anion Redox, and Practical Full Cell.

Mn-based layered oxide cathodes have attracted widespread attention due to high capacity and low cost, however, poor air stability, irreversible phase transitions, and slow kinetics inhibit their practical application. Here, we propose a universal interfacial reconstruction strategy based on converting residual alkali to tunnel phase Na0.44MnO2 for addressing the above mentioned issue simultaneously, using O3 NaNi0.4Fe0.2Mn0.4O2@2 mol % Na0.44MnO2 (NaNFM@NMO) as the prototype material. The optimized material exhibits an initial capacity and energy density comparable with lithium-ion batteries. The reversible anionic redox behavior and charge compensation mechanism of NaNFM@NMO were analyzed and verified by soft X-ray absorption spectrum and in situ X-ray absorption spectrum. Due to the intrinsic stability of the tunnel structure, excellent air stability and highly reversible structure evolution of the NaNFM@NMO cathode material are achieved, which are confirmed by contact angle test, rigorous aging test, and in situ X-ray diffraction. More importantly, the NaNFM@NMO cathode demonstrates a great match with the nonpresodiated hard carbon anode and shows excellent electrochemical performance of the full cell. Additionally, such a strategy could be also applied to modify P2-type cathodes, showing superior universality and good prospects in industrialized production. Overall, the proposed strategy could improve air stability while remaining interfacial and bulk stable simultaneously and will open up a whole new field for the optimization of other electrode materials.

Synthesis of different antioxidant intercalated layered double hydroxides and their enhancement on aging resistance of SBS modified asphalt mixture

The aging of asphalt mixtures shortens the lifespan of asphalt pavements. Incorporating antioxidant intercalated layered double hydroxides (OLDHs) into asphalt is a viable approach to enhance the resistance of the asphalt binder to aging. However, OLDHs hasn’t been optimized and its effectiveness in asphalt mixture is not clear. This study is to synthetize different OLDHs and examine their enhancements on the anti-aging performance of SBS modified asphalt mixture (SMAM). For this purpose, ion-exchange method was employed to intercalate antioxidant 1222, antioxidant 1010, and 3-(3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid into the interlayers of Mg/Al-LDHs to prepare different OLDHs (designated as 1010-LDHs, 1222-LDHs, and 3B-LDHs, respectively). The synthesized OLDHs were characterized by crystal phase, chemical structure, micro-morphology, UV–visible spectroscopy and free radical scavenging tests. The three prepared OLDHs were then added to the SBS modified asphalt (SBSMA) and mixtures were prepared with both OLDHs-containing and non-OLDHs-containing asphalts. Aging tests were conducted, and the changes in pavement performance of different mixtures before and after aging were compared to assess the effects of OLDHs on the anti-aging properties of SMAM. Finally, asphalt binders were extracted from different aged mixtures and subjected to relevant tests. The results indicate that all three antioxidants were successfully intercalated into the LDHs while maintaining the layered structure. Additionally, the incorporation of the three OLDHs improved the ultraviolet and thermal-oxidative aging (TO aging) resistances of the SMAM. Among the three, 3B-LDHs demonstrated the best anti-aging enhancement at the same dosage. These findings offer a reference for studying and applying OLDHs to enhance the anti-aging properties of SMAM.

Mixture proportion optimization and durability evaluation of rejuvenating composite seal

Composite seal (CS) is effective in restoring pavement surface function and prolonging the service life, employing a double-layer structure composed of micro-surfacing and chip seal. Rejuvenating composite seal (RCS) applying rejuvenating agents to the chip seal is dedicated to revitalizing the aged asphalt of the original pavement surface. However, limited studies have focused on enhancing interlayer and temperature performance through optimizing mixture ratios. In this study, a modified emulsified asphalt with self-developed rejuvenating agent was applied, and the orthogonal test considering interlayer shear resistance and high temperature stability was conducted for initially mixture proportion of RCS, then the preliminary ratio was optimized. The proportion for micro-surfacing was determined by mixing test, wet track abrasion test, and loaded wheel sticking sand test. Simultaneously, the recommended asphalt spraying amount of rejuvenating chip seal was determined by utilizing accelerated loading abrasion test. In view of the abrasion resistance, interlayer adhesion, and cracking resistance, the coupled effects of aggregate size and paving rate of rejuvenating chip seal were studied. Long-term wet track abrasion test, freeze-thaw cycle test, and UV aging test were conducted to evaluate the durability. The results show that the asphalt-aggregate ratio of micro-surfacing is 7.1 %. For 4.75 mm or 7 mm rejuvenating chip seal, the recommended asphalt spraying amount is 1.5 kg/m2 or 1.6 kg/m2, and the range of paving rate is 60 %–70 %. For 9.5 mm or 13.2 mm rejuvenating chip seal, the results are 1.7 kg/m2 or 1.8 kg/m2, and 80 %–90 %, respectively. Under the conditions, RCS has better interlayer shear resistance and temperature performance, which can improve durability.

Evaluation of wood coating performance and volatile organic compounds

The aim of this study was to evaluate the environment-performance relationship of surface coating applications on data obtained by measuring the emission rates of volatile organic compounds in polyurethane and water-based varnishes. For this purpose, polyurethane and water-based varnishes from five different companies were applied to the test samples of Entandrophragma cylindricum (sapele) and Piptadeniastrum africanum (dabema), both widely used in the production of urban furniture. Volatile organic compound, hardness and adhesion strength were measured during application. When evaluated in terms of performance, polyurethane varnishes showed superior hardness, while water-based varnishes demonstrated better adhesion after the UV test. The hardness values of polyurethane varnishes before and after the UV aging test were 15,9 s and 79,403 s, respectively, while forwater-based varnishes were , the values were 114,92 s and 75,406 s. The adhesion values of water-based varnishes were 2,885 MPa and 1,18 MPa before and after the UV aging test, and for polyurethane varnishes 3,13 MPa and 1,05 MPa for. When the environment-oriented results were evaluated, the ; emission values of volatile organic compounds in polyurethane varnish applications were found to be significantly higher than those in in water-based varnishes applications. While the total emission rate of volatile organic compounds detected in polyurethane varnishes was 53,63 mg/Nm3, while only one brand of water-based varnishes showed a measurable emission value, recorded at 0,0057 mg/Nm3. The volatile organic compounds emission values of other water-based varnishes were below the device detection limit (<0,0035 mg/Nm3), and therefore could not be measured.

Enhanced temperature range and stability in LaAlO3 NTC ceramics through Ce-Nb codoping

Negative temperature coefficient (NTC) thermistors have garnered increased attention due to their high sensitivity, low thermal inertia, and cost-effectiveness. However, their practical application is significantly constrained by a limited temperature range and poor stability. In this study, a series of Ce-Nb codoped LaAlO3 ceramics were synthesized using the traditional solid-state reaction method, and their unique electrical properties as NTC thermistors were examined. XRD analysis reveals that Ce-Nb codoping induces lattice distortion in the LaAlO3 ceramics. HAADF-STEM shows that Ce replaces La at A-sites, while Nb substitutes for Al at B-sites. XPS indicates that the substitution of Ce4+ for La3+ and Nb5+ for Al3+ facilitates the formation of oxygen vacancies and enhances the number of free carriers. Electrical resistance and UV measurements demonstrate that increasing the Ce and Nb doping levels improves carrier mobility and reduces the band gap of LaAlO3. These modifications significantly enhance the electrical performance and extend the temperature range to 298 K –1773 K when the Ce doping level is 0.2 and the Nb doping level is 0.1. Additionally, aging tests indicate that Ce-Nb co-doping reduces the aging drift of LaAlO3 to 0.38 % after 500 h of aging at 1273 K. This novel Ce-Nb codoped LaAlO3 ceramic, with its broad temperature range and superior stability, shows significant potential for application in NTC thermistors.

Wood Plastic Composite Based on Recycled High-Density Polyethylene and Wood Waste (Sawdust).

The current work presents the reformulation of a composite based on high-density polyethylene obtained through the recycling of blow-molded containers (rHDPE) with natural fiber residues (wood sawdust). This material is technically and industrially known as WPC (wood plastic composite). The original formulation of this material contains 34% high-density polyethylene and 60% sawdust by weight fraction, while the remaining components include additives and coupling agents such as wax (Coupling Agent TPW 813 for plastic woods), stearic acid, and color pigment. The composite material was processed using the profile extrusion method, from which samples were obtained to conduct various experimental tests. The mechanical analysis revealed that both the strength and Young's modulus of the tensile and flexural properties slightly increased with the addition of sawdust to the composite. Additionally, the stiffness was higher compared to high-density polyethylene, indicating a direct relationship between these properties and the amount of sawdust incorporated. Besides this, other characterization methods were performed on the material, including density, hardness, and compression tests, as well as differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), natural and accelerated aging tests, Vicat softening temperature, and heat deflection temperature analysis (HDT). The initial evaluation provides a guide to enhance the most important properties with the aim of using the extruded profiles as pergolas in the real estate sector. Therefore, new formulations are developed with the assistance of Minitab 21 software, maintaining a constant proportion of materials that do not affect the mechanical properties, such as wax, stearic acid, and color pigment. Once the formulations are made, each one is characterized through tensile tests to determine which has the best performance. The formulation with the highest strength is re-characterized using the techniques mentioned in the starting material to obtain a material with the most optimal characteristics.

Study on long-term waterproof performance and failure mechanism of shield tunnel gasket under compression

To study the long-term durability and failure mechanism of ethylene propylene diene monomer (EPDM) rubber gasket in shield segment joints under water-rich environment and compression. In this paper, the hydrothermal accelerated aging test of EPDM rubber gasket under compression was carried out, and the height loss and mechanical properties degradation of the gasket were revealed. Taking the height loss rate as the deterioration index, a time-varying model of gasket aging under water-rich and compressive conditions was established, and the conversion relationship between the test aging and the service life of the gasket under compression was obtained. Furthermore, based on the modified Mooney-Rivlin constitutive, an Euler-Lagrange coupling numerical model considering the effect of water flow is constructed, and the waterproof failure mechanism of the gasket after aging is analyzed. Finally, considering the influence of segment joint deformation in actual service, the evolution law of long-term waterproof performance of gasket under the action of joint dislocation and opening is predicted. The results show that the existence of compression force will seriously aggravate the aging of the gasket, resulting in significant irreversible deformation, and the height loss rate difference between the compressed and uncompressed gaskets is more than 10 times. The waterproof failure process of the gasket after compression aging can be divided into four stages: initial infiltration-splitting-penetration-leakage. During the actual compression service period, the residual performance of the gasket decreases nonlinearly with the increase of the service time, and the loss is extremely significant in the first 5 years of service, and then gradually slows down with the increase of time. In addition, when the joint opening reaches 6 mm, the effective service life of the gasket is shortened to 100 years, the opening amount is 12 mm, and the service life is reduced to 50 years.

DESEMPENHO FÍSICOS EM IDOSOS SEDENTÁRIOS

In the study with 30 sedentary elderly individuals between 60 and 80 years of age, physical and functional capacity tests were performed. In the 6-Minute Walk Test, the elderly individuals aged 60 to 69 years walked an average of 4 meters, while those aged 70 to 79 and 80 years walked 5 and 6 meters, respectively. In the Lawton Scale, which assesses independence in instrumental activities, most elderly individuals showed a need for help, showing that dependence increases with age. In the Katz Scale, 37% of the elderly individuals aged 60 to 69 years, 43% of those aged 70 to 79 years and 20% of those aged 80 years maintained independence in basic self-care activities.

Distinct photooxidation and interface degradation of waterborne epoxy resin coatings on mortar substrate affected by bulk water

Epoxy-based coatings are widely used in engineering but are prone to degrade under aggressive environmental actions, especially in hygrothermal environments. However, the degradation mechanisms of a coating-substrate system under coupled UV irradiation and bulk water remain insufficiently explored. Herein, we designed three parallel accelerated aging tests, including UV irradiation only, UV/flush, and UV/submerged, on a waterborne epoxy resin (WER) coating on cement mortar substrate. The chemical structure, micro-morphology, and hydrophilicity over aging time were comprehensively characterized by the tests of attenuated total reflectance Fourier transformation infrared spectrometer (ATR-FTIR), scanning electron microscopy (SEM), image analysis, water contact angle (WCA). Results show that the UV/flush environments induced more micro-pinholes on the WER outer surface than the neat UV photooxidation. The UV/ submerged environment led to a blistering rate over 24% after 60 d's exposure owing to the significant osmotic pressure built between the inner and outer surfaces of the WER coating. Additionally, the physicochemical and microstructure changes to the outer surface of WER also caused the changes of WCA. The osmotic, hydrolysis, and thermal stresses were evaluated to clarify the water-accelerated photooxidation and interface degradation mechanisms. These findings contribute to a deeper understanding of epoxy coating degradation mechanisms in response to environmental stressors, and offer insights for enhancing coating performance under varying conditions.

Reliability research of thyristors for HVDC transmission system

The long-term operation performance of HVDC transmission systems is significantly influenced by the reliability of thyristors. However, the current reliability research of thyristors is mainly based on the leakage current and there is no comprehensive degradation characteristics of thyristors. In this article, the degradation characteristics of thyristors under voltage and temperature accelerated ageing tests are obtained, including the reverse recovery characteristic, on-state characteristic, blocking characteristic and gate characteristic. The reverse recovery characteristic obviously degrades under the voltage accelerated ageing tests. The reverse recovery charge and reverse recovery time decrease by over 10% after the tests. Seven thyristors operating for a certain number of years from two HVDC stations are tested, and the results verify the thyristor degradation characteristics obtained from the ageing tests. Moreover, the mechanisms of the leakage current and reverse recovery characteristic are analyzed in detail.

Risk Factors for Anemia in Pulmonary Tuberculosis Patients in the Treatment Phase

Tuberculosis lungs is disease infectious disease caused by bacteria Mycobacterium tuberculosis. Tuberculosis is still a disease become threat health Indonesian society which leads to illness , disability and death tall so that need existence mitigation. Research objectives know factor risk the occurrence of anemia in patients tuberculosis lungs in phase treatment . Study This is study retrospective analytic case control Study carried out at the Community Health Center Very Beautiful Subdistrict Genuk City of Semarang. Population all TB patients who are undergo treatment at the Community Health Center Bangetayu. Research sample This from the total population namely 34 case and control patients. The results of 34 respondents case control there is level hemoglobin in patients Tuberculosis lungs with anemia (case) as many as 17 respondents experienced decline hemoglobin levels, namely man with an average hemoglobin level of 12.2 gr/dL (7 respondents), women with The average hemoglobin level was 10.6 gr/dL (2 respondents). A total of 17 respondents non - anemic control , namely the majority is normal with type sex Woman with an average Hemoglobin level of 12.61 gr/dL (17 respondents ). Based on characteristics what kind sex male 29.41% and gender sex women 11.76%. Decrease hemoglobin levels , namely man with an average hemoglobin level of 12.2 gr/dL (5 respondents), women with average hemoglobin level 10.6 gr/dL (2 respondents). Based on characteristics of the type sex women 70.59% (24 respondents) and men 29.41% (10 respondents). Based on characteristics age category adults 64.71% (22 respondents), elderly 23.53% (8 respondents), infants and children 11.76% (4 respondents), and adolescents 0.00% (0 respondents). The results of the bivariate test of hemoglobin levels, age , and type sex there is connection between hemoglobin levels, age, and type sex to Pulmonary Tuberculosis patients in phase treatment. The most influential risk factor o to the occurrence of anemia in patients with pulmonary tuberculosis in phase treatment namely on the variables type sex that is own risk of 3,429. Next followed by variables hemoglobin levels that have risk of 0.370. Age No there is factor risk the occurrence anemia in pulmonary tuberculosis patients in phase treatment. The conclusion of this study is that hemoglobin levels and sex are risk factors for anemia in patients with pulmonary tuberculosis in the treatment phase. Anemia can affect the diagnosis, prognosis, complications, and response to tuberculosis therapy, so that tuberculosis patients can maintain nutritional intake and therapy compliance to suppress the progression of the disease.

Monoclonal Gammopathy in Patients with Neuropathy.

The incidence of monoclonal gammopathy of undetermined significance (MGUS) in the population of over 50-year-olds is approximately 3% and increases with age. The association between MG and neuropathy has been of interest for several years, but the causal relationship has not yet been clarified. For 682 patients who visited the Department of Neurology and requested tests for MG work-up, we retrospectively collected demographic and clinical information, such as age, gender, diagnosis, and neurologic and laboratory test results, from their medical records. Out of a total of 682 patients who were suspected of neuropathy and tested for monoclonal gammopathy (MG), twelve (1.76%) showed MG on their serum protein electrophoresis. The most common form was IgM-κ with five patients, followed by IgG-κ, IgG-λ, and biclonal IgG-λ and IgA-κ. The results of the immunoglobulin quantitation test and free light chain assay showed that involved M-protein values in these patients were increased. Some patients were positive for anti-myelin-associated glycoprotein (MAG) antibody, anti-GD1b IgM antibody, anti-GM1 IgG & IgM antibody, and anti-cardiolipin IgM antibody. Also, some had antinuclear antibody (ANA) or antineutrophil cytoplasmic antibody (ANCA). In the future, it is necessary to investigate the pathogenic relationship between M-protein and autoantibodies in patients with neuropathies.

Robust Dual Crosslinking Ionic Network for High‐Performance Cis‐1, 4‐Polyisoprene Latex/Sodium Alginate Composites

ABSTRACTExisting natural rubber latex (NRL) medical gloves are problematic due to protein allergies and poor sweat resistance. Cis‐1,4‐polyisoprene latex (IRL) is an ideal alternative of NRL for free from proteins, while its poor mechanical properties severely restrict the application as medical gloves. Here we proposed a straightforward strategy of latex compounding to incorporate sodium alginate (SA) into IRL. High‐performance IRL/SA composite films with remarkable strength and super hydrophilic properties were achieved benefiting from a dual ionic crosslinking network. The properties and the morphology of the IRL/SA composite latexes and films were investigated. Experimental results revealed that the composite latexes had a stable state, possessed good film‐forming abilities and exhibited outstanding mechanical properties. The sodium alginates were uniformly dispersed throughout the IR matrix. Compared with IRL films, the tensile strength of the IRL/SA (30 phr) composite film increased by 30.7%. Notably, the IRL films exhibited a swelling degree of 0.05%, while IRL/SA (30 phr) composite film increased to 14.5%. Moreover, swelling in PBS buffer solution has little effect on the mechanical properties of the IRL/SA composite films. Thermal oxygen aging test suggested that the tensile strength change rate exhibited a decrease of approximately 30%, closely to that of NRL. The current composite films are well‐suited for high‐end medical applications.

Development and performance evaluation of a polyurethane elastomer based seamless expansion joint for bridges

PurposeThis study aims to address the degradation and damage of traditional bridge expansion joints by proposing a seamless expansion joint device based on polyurethane elastomer (PUE).Design/methodology/approachA series of laboratory experiments were conducted to evaluate the performance of PUE, including elasticity recovery, interfacial bonding and hygrothermal aging tests. Indoor model tests were also designed to analyze PUE's performance in actual bridge expansion structures. Based on these evaluations, the design of a seamless PUE expansion joint structure was completed.FindingsThe study reveals that PUE achieves optimal interfacial bond strength with PUC at −30°C after 7 h of curing and adhesive application, with a tensile strength of 9.2 MPa. PUE's elongation at break exceeds 3% at −30°C and retains its toughness and tensile strength after hygrothermal aging. When the beam end rotation reaches 0.0144 rad, PUE maintains a linear elastic state. With a groove width of 340 mm, PUE can withstand compressive displacements over 40 mm and tensile displacements up to 60 mm.Originality/valueThe findings highlight the excellent elasticity recovery and toughness characteristics of PUE, demonstrating the significant improvement in durability of the PUE seamless expansion joint structure and the rationality of the groove width calculation method based on the elongation at break of PUE. The broader impact of this study lies in its potential to innovate the design and maintenance strategies of bridge expansion joints.