Test Methods Research Articles

Enhancing fiber/matrix interface adhesion in polymer composites: Mechanical characterization methods and progress in interface modification

The interface between the fiber and polymer matrix is a crucial region that plays a major role in the mechanical performance of fiber reinforced polymer composites (FRPCs) materials. The properties of this zone are recognized to have a significant influence on the fracture and failure of FRPCs. As a result, strong adhesion at the interface is required for effective stress transfer and load distribution within the composite material. In light of this, the aim of this work is to provide an up-to-date review of test methods for assessing fiber/matrix interface adhesion in FRPCs under static and dynamic loadings, along with advancements in interface modification techniques. At the outset, we give an overview of the different modification treatments used thus far, alongside interface testing methods, in order to optimize fiber/matrix compatibility, improve interfacial bonding and scrutinize their impact on interfacial adhesion properties. Particular attention is then focused on the description of the main mechanical characterization techniques used to assess the fiber/matrix interfacial properties. In the final outlook, we highlight the key findings and discuss potential directions for characterization of the fiber/matrix interface.

Combined Prediction of Dust Concentration in Opencast Mine Based on RF-GA-LSSVM

Accurate prediction of dust concentration is essential for effectively preventing and controlling mine dust. The environment of opencast mines is intricate, with numerous factors influencing dust concentration, making accurate predictions challenging. To enhance the prediction accuracy of dust concentration in these mines, a combined prediction algorithm utilizing RF-GA-LSSVM is developed. Initially, the random forest (RF) algorithm is employed to identify key features from the meteorological and dust concentration data collected on site, ultimately selecting five indicators—temperature, humidity, stripping amount, wind direction, and wind speed—as the input variables for the prediction model. Next, the data are split into a training set and a test set at a 7:3 ratio, and the genetic algorithm (GA) is applied to optimize the least squares support vector machine (LSSVM) model for predicting dust concentration in opencast mines. Additionally, model evaluation metrics and testing methods are established. Compared with LSSVM, PSO-LSSVM, ISSA-LSSVM, GWO-LSSVM, and other prediction models, the GA-LSSVM model demonstrates a final fitting degree of 0.872 for PM2.5 concentration data and 0.913 for PM10 concentration data. The GA-LSSVM model clearly demonstrates a strong predictive performance with low error and high fitting. The research results can serve as a foundation for developing dust control measures in opencast mines.

Can Soil Spectroscopy be a Strong Alternative to the Conventional Methods of Analysis?

Soil is considered as the source of life on the globe. Although, numerous research studies, the soil is not completely understood whereas it is dynamic complex matrix include many simultaneous processes. The conventional methods of soil testing are the most reliable for assessing the land productivity and management. Unfortunately, these methods are time consuming and laborious as well as costly and hazardous to the environment. Therefore, the soil spectroscopy technique provides the functions of detecting, characterizing, quantifying and mapping several soil properties based on the uses of different kinds of the sensors (ground-based, airborne-based, and satellite-based). An integration of soil spectroscopic data, data processing, and modelling is considered as an effective tool for estimating soil parameters. Although these advanced techniques able to predict the majority of soil properties, there are some of these properties require more experiments for building accurate calibration models for estimation. Moreover, creating accurate soil spectral libraries (SSLs) for specific areas or soil types is very crucial for saving time, effort, expenses of soil surveying, sampling, and analysis. The application of these SSLs has a big limitation of the continuous variability of the soil properties over time. Thus, establishing extensive spectral libraries is important and mandatory for covering the small scaled areas’ variabilities as well as available soil types. Till now, the soil spectroscopy is not entirely replacing the conventional testing methods of soils because these techniques need future applications to be trusted and guaranteed of their effectiveness.

Quality Assessment of Cryopreserved Peripheral Blood Stem Cell Products: Evaluation of Two Methods for Flow Cytometric Viability Testing

ABSTRACTIntroductionThe standard flow cytometry method for viability testing using 7‐aminoactinomycin D (7‐AAD) determines cells in necrosis and late apoptosis. The colony‐forming unit (CFU) assay, which evaluates the proliferation ability of HSCs, is also used in graft quality assessment despite known deficiencies that make this assay impractical in routine clinical settings. The aim was to compare the effectiveness of the flow cytometry 7‐AAD/annexin V method with the 7‐AAD method in assessing the quality of HSCs in autologous and allogeneic peripheral blood stem cell (PBSC) products.MethodsThirty autologous and 30 allogeneic fresh and thawed cryopreserved PBSC products were included in this study. The viability of HSCs was determined using the 7‐AAD method and 7‐AAD/annexin V method on a flow cytometer, while their clonogenic capacity was assessed by CFU assay.ResultsThere was an excellent correlation for CD34+ cell viability between the 7‐AAD and the 7‐AAD/annexin V method for fresh samples (Rs = 0.930, p < 0.001) and a good correlation for thawed PBSC samples (Rs = 0.739, p < 0.001). Excellent correlation was observed for post‐thaw CD34+ cell recovery between the two methods for viability (Rs = 0.980, p < 0.001). Statistical analysis showed a weak correlation between CFU‐GM recovery and CD34+ cell recovery, regardless of which viability testing method was used (7‐AAD method p = 0.021, Rs = 0.298; 7‐AAD/annexin V method p = 0.029, Rs = 0.282).ConclusionsResults of this study showed that in the quality assessment of cryopreserved PBSC product viability, the 7‐AAD/annexin V method had no added value compared to the 7‐AAD method, which was suitable enough for routine quality control of cryopreserved autologous and allogeneic PBSC samples.

Modal analysis of Lamb waves of steel pipeline with calcium deposits

The relevance of the work lies in the study of the effect of calcium deposits of various thicknesses on the inner walls of the pipeline on the parameters of its own vibrations.OBJECTIVE: To construct a mathematical model of a steel pipeline without deposits and with calcium deposits of various thicknesses on its inner walls. To perform a modal analysis of the natural vibrations of the steel pipeline. Theoretically confirm the dependence of the change in the oscillation frequency of the pipeline when exposed to sediments.METHODS. The paper highlights a method for analyzing the natural frequencies of the pipeline using the acoustic method of non-destructive testing, since it can be implemented with one-way access and does not violate the integrity of the object of control. In solving this problem, the method of mathematical analysis in the software package of finite element analysis was used. results. The article describes the relevance of the topic, discusses the main methods of non-destructive testing, and defines Lamb waves. A mathematical model of a steel pipeline section with out internal deposits and with calcium deposits of 5 different thicknesses has been constructed.CONCLUSION. Calculations have shown that the natural vibration frequencies of the pipeline without deposits and with calcium deposits change in the direction of increasing values, the frequency increase occurs in waves. The highest frequency values are obtained when modeling calcium deposits with a thickness of 10 mm on the walls of the pipeline.

Abstract A121: Cervical cancer screening among Hispanic women in Lake County, Indiana: Knowledge, practices and willingness to adopt new testing methods

Abstract Cervical cancer screening has significantly reduced incidence and mortality rates in the U.S., yet disparities in screening rates persist. Hispanic women are 40% more likely to be diagnosed and 30% more likely to die from cervical cancer compared to non-Hispanic whites. Indiana ranks among the top ten states with highest rates of cervical cancer mortality, with Lake County having the highest mortality rates and largest Hispanic population in the state. Clinical screening guidelines now include primary HPV testing without cytology allowing for innovations like HPV self-sampling and rapid testing, which can increase screening coverage among medically underserved populations. This study aimed to examine knowledge, practices, attitudes towards cervical cancer screening, and willingness to adopt screening innovations among Hispanic women in Lake County, Indiana. A mixed-methods study with an online cross-sectional survey of white, non-Hispanic and Hispanic individuals with a cervix aged 21-65 residing in Lake County (n=231), followed by in-depth interviews with a subset of Hispanic respondents (n=9). Outcome variables included cervical cancer knowledge, willingness to adopt HPV self-sampling at home/ in clinic, and willingness to adopt an HPV rapid test. A knowledge score was created using a scale based on 7 questions. Using SPSS, a t-test to compare knowledge score means and associations between demographic and outcome variables were analyzed. Interviews were thematically analyzed using NVIVO software. Most participants identified as Hispanic (58%) and were 31 or older (58%). 71.9% had been screened for cervical cancer, however, 24.7% reported never or being overdue for screening. There was a significant difference in means of knowledge scores between white, non-Hispanic (M=4.17, SD=2.25) and Hispanics (M=3.23, SD=2.15) (p-value <.005). Among those willing to self-sample at home (51.9%), Hispanics were less willing (37.3%) compared to white, non-Hispanic (72.2%). Factors negatively associated with willingness to self-sample include being Hispanic (OR: 0.28, 95% CI: 0.13-0.62), having Medicaid (OR: 0.36, 95% CI: 0.14-0.94), and being uninsured (OR: 0.16, 95% CI: 0.05-0.60). Factors positively associated with willingness include never been married (OR: 2.75, 95% CI: 1.16-6.50), unemployed (OR: 2.75, 95% CI: 1.16-6.50), high-risk perception (OR: 2.79, 95% CI: 1.13-6.88), and having used rapid tests before (OR: 2.83, 95% CI: 1.13-7.31). Qualitative analysis identified concerns among participants about performing the test incorrectly (lack of self-efficacy) and remembering to perform the test. Benefits included increased comfort and less fear. While some testing methods are often considered more beneficial for cervical cancer screening among vulnerable populations, our study revealed that these populations may not readily accept or adopt them for various reasons. Understanding and addressing these is critical to increasing willingness to adopt new testing methods. Future efforts involve focus groups with Hispanic women to expand on these findings. Citation Format: Layla A. Claure, Lara Balian, Natalia Rodriguez. Cervical cancer screening among Hispanic women in Lake County, Indiana: Knowledge, practices and willingness to adopt new testing methods [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr A121.

Equation-of-motion regularized orbital-optimized second-order perturbation theory with the density-fitting approximation.

The density-fitted equation-of-motion (EOM) orbital-optimized second-order perturbation theory (DF-EOM-OMP2) method is presented for the first time. In addition, κ-DF-EOM-MP2 and κ-DF-EOM-OMP2 methods are implemented with the addition of κ-regularization. The accuracy of the DF-EOM-OMP2, κ-DF-EOM-MP2, and κ-DF-EOM-OMP2 methods are compared to the density-fitted EOM-MP2 (DF-EOM-MP2), EOM coupled-cluster (CC) singles and doubles (DF-EOM-CCSD), and EOM-CCSD with the triples excitation correction model [EOM-CCSD(fT)] for excitation energies of many closed- and open-shell chemical systems. The excitation energies computed using different test cases and methods were compared to the EOM-CCSD(fT) method and mean absolute errors (MAEs) are presented. The MAE values of closed- and open-shell cases (closed-shell organic chromophores set, open-shell set, peptide radicals set, and radical set) according to the EOM-CCSD(fT) method show that the κ-regularization technique yields highly accurate results for the first excited states. Our results indicate that the κ-DF-EOM-MP2 and κ-DF-EOM-OMP2 methods perform noticeably better than the DF-EOM-MP2 and DF-EOM-OMP2 methods. They approach the EOM-CCSD quality, at a significantly reduced cost, for the computation of excitation energies. Especially, the κ-DF-EOM-MP2 method provides outstanding results for most test cases considered. Overall, we conclude that the κ-versions of DF-EOM-MP2 and DF-EOM-OMP2 emerge as a useful computational tool for the study of excited-state molecular properties.

User experience testing methods: Conclusions from the literature

Industry 4.0 focuses on the digitalization of production processes and technological innovation. The concept of Industry 5.0 puts the focus on human-centricity, sustainability, and resilience at the heart of research and development and innovation (R&D&I) processes to allow industry to serve humanity with a long-term vision that considers planetary boundaries. Replacing the technology-driven approach with a fundamentally human-centric approach requires a deep understanding of the working environment and workers interacting with machines to optimize worker well-being, working conditions, and job outcomes. Analyzing computer work User eXperience (UX) in industrial environments is vital. However, user perceptions are usually hidden and a challenge to detect. Therefore, measuring and monitoring perceptions, emotional reactions, subjective elements, preferences, and attitudes in the relationships between usability, work performance, and workload is crucial. This study provides conclusions of a literature review on user experience studies focusing on UX testing methods and the disciplines linked to industrial diversification. Based on literature analysis, it identifies UX testing methods and create own grouping to analyze them. It also examines the disciplinary context of user experience testing.

Enhanced mechanical, thermal, water and UV aging resistance properties of bamboo fiber/HDPE composites through silane coupling agent modified nano-SiO2-TiO2

Nano-TiO2 is widely employed to enhance the properties of plant fiber reinforced thermoplastic polymer composites due to its chemical inertness, anti-aging, and anti-bacterial properties. However, the enhancement of bamboo fiber/high-density polyethylene (BF/HDPE) composites is limited by the high photocatalytic activity of nano-TiO2 and its poor compatibility with the BF/HDPE matrix. This study employs an organic-inorganic co-modification to prepare BF/HDPE composites reinforced with silane coupling agent KH550 modified nano-SiO2 coated nano-TiO2 (KH550/SiO2-TiO2) by spray coating and melt mixing methods, and the properties of the composites were tested and characterized. The effects of KH550 and KH550/SiO2-TiO2 content on the properties of modified BF/HDPE composites, including mechanical properties, water absorption, thickness swelling rate, water contact angle, thermal stability, and UV aging resistance，which were characterized using methods of mechanical tests, FTIR, UV-Vis, XPS and SEM, both before and after modification. The results indicate that KH550 effectively improves the agglomeration phenomenon and enhances the dispersibility of nano-SiO2-TiO2 in the BF/HDPE composites. The optimal thermal stability is achieved when the BF/HDPE composites modified with a 5 wt% KH550/SiO2-TiO2, while BF/HDPE composites modified with a 3 wt% KH550/SiO2-TiO2 exhibit the better mechanical properties, water resistance, and UV aging resistance compared to other contents. Flexural strength and modulus of KH550/SiO2-TiO2 modified BF/HDPE composites increased by 18.71 % and 17.92 %, tensile strength and modulus increased by 7.74 % and 21.92 %, respectively. The 480-hour water absorption and thickness swelling rate decreased by 18.68 % and 20.73 %, respectively, and the contact angle increased by 19.17°; better thermal stability and color stability was observed. The spray coating method was more effective in improving the properties of the modified BF/HDPE composites than the melt mixing method. Comprehensive analysis indicates that the mechanical properties, water resistance, thermal stability, and UV aging resistance of the BF/HDPE composites reinforced with 3 wt% KH550/SiO2-TiO2 prepared by the spray coating method are significantly enhanced.

EHealth and mHealth in Antimicrobial Stewardship Programs

Background: The global need for rapid diagnostic methods for pathogen identification and antimicrobial susceptibility testing (AST) is underscored by the increasing bacterial resistance and limited therapeutic options, especially critical in sepsis management. Summary: This review examines the aspects of the eHealth and mHealth in Antimicrobial Stewardship Programs (ASPs) to improve the treatment of infections and rational use of antimicrobials. Key Messages: The evolution from traditional phenotype-based methods to rapid molecular and mass spectrometry techniques has significantly decreased result turnaround times, improving patient outcomes. Despite advancements, the complex decision-making in antimicrobial therapy often exceeds the capacity of many clinicians, highlighting the importance of ASPs. These programs, integrating mHealth and eHealth, leverage technology to enhance healthcare services and patient outcomes, particularly in remote or resource-limited settings. However, the application of such technologies in antimicrobial management remains underexplored in hospitals. The development of platforms combining antimicrobial prescription data with pharmacotherapeutic algorithms and laboratory integration can significantly reduce costs and improve hospitalization times and mortality rates.

Study of the effects of shallow-buried charge parameters on the lower limb injuries of occupant in special vehicle body

In the process of military missions, special vehicles often encounter shallow buried charge threats that will greatly affect the safety of the occupants. To study the integrated effects of shallow buried charge detonation point, height-to-diameter ratio, burial inclination, weight, and other key parameters on the lower limb injuries of occupant, this study was based on the special body of a shallow buried explosive test and numerical calculation methods. The reliability of the numerical model and the load effect mechanism of the shallow burial charge were studied. Based on this, the lower limb injuries response law of occupant was analyzed with respect to each parameter. The results showed that the bottom charge load mainly came from two-stage ejection loading, in which the first stage was a strong load with short-duration local impact loading and the second stage was a weak load with long-duration extended range loading. By comparing the lower limb injury response of occupant under different charge parameters, we found that the weight of charge had the greatest effect on the extent of occupant injury, followed by the height-to-diameter ratio and burial inclination, while the detonation position had a relatively small effect on the injury magnitude. Finally, a comprehensive prediction model of the lower limb injuries of occupant was obtained by using the Latin hypercube sampling method and the least-squares method, and it was verified that the model had a good matching accuracy.

Bioplastic Production Using Aloe vera Gel as Plasticizer: A Sustainable Approach

The utilization of bioplastics has garnered considerable interest because of their capacity to alleviate environmental issues related to conventional petroleum-based plastics. This study explores the feasibility of utilizing Aloe vera gel as a plasticizer in bioplastic production, aiming to enhance biodegradability and sustainability. Aloe vera gel, a natural polysaccharide-rich material, offers promising characteristics such as biocompatibility, non-toxicity, and abundant availability. This research involves the formulation of bioplastic blends comprising biodegradable polymers such as starch from Cassava, along with varying concentrations of Aloe vera gel as a plasticizer. The resulting bioplastics' mechanical, thermal, and biodegradation properties are systematically evaluated using standard testing methods. Preliminary results demonstrate that Aloe vera gel effectively improves the flexibility and processability of bioplastic materials while maintaining adequate mechanical strength. Thermal analysis reveals enhanced thermal stability in some formulations, indicating the potential for diverse applications. The bioplastic film had a tensile strength of determined to be 5.53 N. Additionally, the percent mean breaking elongation was found to be 1.2%, indicating the extent to which the film can stretch before reaching its breaking point. The thickness yields a result of 0.05 mm. Moreover, biodegradation studies indicate accelerated degradation rates in composting conditions, highlighting the eco- friendly nature of Aloe vera-based bioplastics. This research underscores the possibility of Aloe vera gel as a sustainable alternative plasticizer in bioplastic production, offering a promising avenue for reducing reliance on fossil-based materials and addressing environmental concerns associated with plastic waste pollution.

Challenges in Ground-Penetrating Radar Application in Structural Elements: Determination of the Dielectric Constant of Glued Laminated Timber Case Study

In this paper, some of the basic information on Ground-Penetrating Radar (GPR), its applications (especially in the field of civil engineering) and limitations are presented. As a non-destructive technique, GPR is a powerful tool for the investigation of structures and structural members, roads, geological layers, archaeological sites and many more. The technology is based on electromagnetic radiation in the UHF/VHF range (10 MHz to 3 GHz). The choice of the frequency depends on the intended use, depth and size of the target and medium where the target is located. Joined with other testing methods (ultrasound method, dynamic methods with forced or ambient vibrations, electrical conductivity testing, etc.), GPR can provide a deep insight into the investigated object. However, like many other non-destructive methods, the choice of input parameters may affect the results. In this regard, a case study presented in this paper demonstrates not only different applications of GPR in civil engineering but also the determination (calibration) of one of those input parameters: the dielectric constant of glued laminated timber. The challenge here was not only to investigate the influence of the direction of measurements with regards to the direction of the fibers but also to acknowledge the contribution of the test antenna used during testing and dielectric constant calibration.

Evolving strategies in microbe identification—a comprehensive review of biochemical, MALDI-TOF MS and molecular testing methods

Abstract Detection and identification of microorganisms are the first steps to guide susceptibility testing and enable clinicians to confirm diseases and guide therapy. The faster the pathogen identification is determined, the quicker the appropriate treatment can be started. In the clinical microbiology laboratory, multiple methodologies can be used to identify organisms, such as traditional biochemical testing or more recent methods like MALDI TOF MS and nucleic acid detection/identification assays. Each of these techniques has advantages and limitations, and clinical laboratories need to determine which methodology is best suited to their particular setting in terms of clinical needs, availability of technical expertise and cost. This article presents a concise review of the history, utilization, advantages and limitations of the main methods used for identifying microorganisms in microbiology laboratories.

Calibration of the spherical tip radius of Rockwell hardness diamond indenters using a confocal laser scanning microscope

Abstract The precise form of an indenter is an essential part of hardness testing methods. It is therefore incumbent upon a user to ensure that the indenter geometry is calibrated before performing a hardness test. A geometric change of the tip radius by ±5 μm can cause a change of approximately 0.6 units of Rockwell hardness C scale (HRC) in a material with a hardness of 65 HRC. Keeping in mind that the measurement uncertainty is typically of the order of 0.3 HRC, it is critical to know the true value of the tip radius. Typically, tactile methods are used to determine the tip radius of a Rockwell hardness diamond indenter from the measured surface topography. Two main drawbacks of tactile measurements are the long duration of measurement and the limitation in capturing surface features of sizes smaller than the probe tip radius of 2 μm. Both could be overcome by using an optical 3D measurement. Confocal laser scanning microscopes (CLSM) allow a fast contactless 3D-mapping of the surface of Rockwell hardness diamond indenters and can be used to obtain geometric information such as the tip radius. The accuracy of these 3D measurements is still under question. Within this work, some of the influencing factors for fast 3D surface measurement are investigated. Using a CLSM with a 50x objective lens and a numerical aperture of 0.95, typical shape deviations of Rockwell diamond indenters are shown. Furthermore, an improved 3D based point cloud method for the evaluation of the indenter radius is presented. The aim of this paper is to explore the capabilities and limits of CLSM to obtain the 3D surface of a Rockwell hardness diamond indenter in order to calibrate the tip radius and compare their results with measurements from traceable stylus instruments.

Research progress on high-temperature properties of carbon fiber reinforced polymer composites for cables

Carbon fiber reinforced polymer composites (CFRP) cable has advantages of lightweight, high strength, and excellent durability, providing a new materials for cables and bringing out potential breakthrough in spanning capacity of structures. At present, CFRP cable has already been applied in some engineering bridges. The fire resistance performance of CFRP cable is critical for ensuring structure safety when suffering accidental fire disaster, and clarifying mechanical performance deterioration and failure mechanism of CFRP cable at elevated temperature is fundamental for research of its fire resistance. This paper summarizes current research progress on high-temperature properties of CFRP cable from two levels, including epoxy resin matrix and CFRP composites. Firstly, at resin matrix level, mechanical properties of epoxy resin and its degradation at elevated temperatures are reviewed and analysed, and potential ways to improve high-temperature performance of epoxy resin are suggested. Secondly, at CFRP composites level, high-temperature properties test methods and mechanical performance of CFRP composites in longitudinal direction and transverse direction at elevated temperatures are summarized and discussed. In addition, research shortage of high-temperature properties of CFRP cable is summarized, and corresponding further research is recommended.

Investigating NanoLuc-EGFR engineered cell lines for real-time monitoring of EGFR protein dynamics in live cells

Evaluating the steady-state protein level of the EGFR in live cells presents significant challenges compared to measuring its kinase activity. Traditional testing methods, such as immunoblotting, ELISA, and immunofluorescence assays, are generally restricted to fixed cells or cell lysates. Despite their utility, these methods are cumbersome and provide only intermittent snapshots of EGFR levels at specific time points. With emerging trends in drug development shifting toward engineering novel agents that promote protein degradation, rather than simply inhibiting kinase activity, a tool that enables real-time, quantitative detection of drug effects in live cells could catalyze advances in the field. Such an innovation would expedite the drug development process, enhancing the translation of research findings into effective, patient-centered therapies. The NanoLuc-EGFR cell line, created through CRISPR genome editing, allows for the continuous tracking and analysis of EGFR protein levels and their degradation within live cells. This approach provides quantitative monitoring of protein dynamics in real time, offering insights that go beyond absolute protein levels to include aspects such as protein stability and degradation rate. Using this cell line model, we observed that AT13387 and H84T BanLec induce EGFR degradation in A549-HiBiT cells, with the results confirmed by immunoblotting. In contrast, Erlotinib, Osimertinib, and Cetuximab inhibit EGFR phosphorylation without altering total EGFR levels, as validated by the HiBiT luciferase assay. The NanoLuc-EGFR cell line marks a significant advancement in understanding protein regulation and serves as an instrumental platform for investigating targeted therapies that modulate protein kinases, especially those that induce protein degradation.

A Novel Fractal Model for Contact Resistance Based on Axisymmetric Sinusoidal Asperity

In this paper, a novel fractal model for the contact resistance based on axisymmetric sinusoidal asperity is proposed, which focuses on the resistance characteristics of the rough interface at a microscopic scale. By introducing the unique geometric shape of axisymmetric sinusoidal asperity, and combining it with a three-dimensional fractal theory, the micro-morphology characteristics of the rough interface can be characterized more precisely. Subsequently, by conducting a theoretical analysis and numerically solving the deformation mechanisms of asperities on the rough interface, a refined model for contact resistance is constructed. This research comprehensively employs theoretical analysis, numerical simulation, and experimental testing methods to deeply explore the current transmission mechanisms during the contact process of the rough interface. The findings suggest that the proposed model is capable of precisely capturing the intricate interplay of various factors, including contact area, contact load, and material properties, with the contact resistance. Compared to the existing models, the presented model demonstrates significant advantages in terms of prediction accuracy and practicality. This research provides an important theoretical basis and design guidance for optimizing the electrical performance of the rough interface, which has great significance for engineering applications.

Lightning damage characteristics of Cf/SiC based on ultrasonic and multi‐nondestructive testing methods

AbstractAccording to the characteristics of the internal damage of the Cf/SiC composite material after the lightning strike, this article establishes a high‐energy ultrasonic excitation, reception, and high‐resolution ultrasonic testing model, achieving high‐energy and high‐resolution ultrasound C‐scan detection of Cf/SiC composite material samples after lightning strikes, and combining digital X‐ray and computed tomography methods for damage analysis. When the lightning energy is gradually increased, the lightning stratified damage will occur inside the sample, and the delamination damage area reaches the maximum value of 25182 mm2 at the lightning energy of S4. Subsequently, as the energy increases, significant needle‐like damage is generated at the needle‐stitched area inside the sample, and the area of delamination damage gradually decreases. When the energy continues to increase to the lightning strike energy of S6, as the energy increases, the number of needle‐like damage in the sample continues to grow, and penetrating injury appears at the needle suture site. At S8, the maximum number of needle‐like lightning damage occurred, with 53 damage points and a total volume of 256.86 mm3, respectively. Through comprehensive analysis, Cf/SiC has excellent resistance to lightning damage, but the needle‐stitched carbon fiber in the thickness direction significantly reduces its resistance to lightning penetration.

Inter-laboratory variation for urine albumin among laboratories in a Swedish external quality assessment scheme 2005–2023

IntroductionIncreased albuminuria is associated with elevated mortality. Urine albumin (U-ALB) above 20 mg/L or albumin-to-creatinine ratio (U-ACR) of 3 g/mol are indicative of moderately increased albuminuria. Due to limited standardization among U-ALB methods, diagnosis of increased albuminuria might prove difficult. Materials and methodsData from Equalis’s external quality assessment scheme for low U-ALB levels during 2005–2023 were categorized according to manufacturer and divided into central laboratory (CLAB) and point-of-care testing (POCT) methods. Manufacturer median values were compared to total group mean consensus values and manufacturer CV% was compared at different U-ALB levels. ResultsCLAB was generally closer to consensus values and had lower CV% than POCT at U-ALB levels around 20 mg/L. For CLAB, Roche methods were approximately equal to consensus U-ALB, Abbott 4 % above, and Siemens 5 % below. For POCT, HemoCue was 1 % below, Siemens 7 % above, and Abbott 8 % below. For U-Creatinine, all manufacturers generally had a good agreement differing on average by 1–4 % from consensus. ConclusionsAlthough U-ALB methods generally meet The National Kidney Disease Education Program (NKDEP) recommendations of method bias less than 13 % and imprecision less than 30 %, differences among manufacturers have increased over the last years, with 2023 showing the largest differences between methods. This highlights the need for guidelines for albuminuria and ACR to take method differences into consideration, but also for implementation of suitable urine reference materials.