Test Methods Research Articles

Activity of antibiotics against Burkholderia cepacia complex in artificial sputum medium.

Burkholderia cepacia complex (Bcc) is a collection of intrinsically drug-resistant Gram-negative bacteria that cause life-threatening disease in people with cystic fibrosis (CF). Standard antimicrobial susceptibility testing methods have poor predictive value for clinical outcomes in Bcc infections, probably due in part to differences between in vitro testing conditions and the environment in which Bcc grow in the lungs of people with CF. To compare the activity of commonly used antibiotics under standard in vitro testing conditions with activity in conditions mimicking those found in vivo. Two Bcc strains were grown alone and with six different antibiotics (minocycline, ceftazidime, meropenem, tobramycin, levofloxacin, trimethoprim-sulfamethoxazole) in two different media: standard cation-adjusted Mueller-Hinton broth and an artificial sputum medium designed to simulate the environment in the lungs of people with CF through addition of components including mucin, free DNA and amino acids. Two different starting conditions were used for time-kill assays: a standard ∼5 × 106 cfu/mL inoculum, and a high-density inoculum in which bacteria were grown for 72 hours before addition of antibiotics. Growth detection was performed by colony enumeration and by detection of resazurin reduction. There were major discrepancies between standard susceptibility results and activity in our models. Some antibiotics, including ceftazidime, showed minimal activity in all time-kill assays despite low minimal inhibitory concentrations, while others, notably tobramycin, were more active in high-density growth conditions than in standard time-kill assays. This work underscores the urgent need to develop more clinically relevant susceptibility testing approaches for Bcc.

Physical performance, durability, and carbon emissions of recycled cement concrete and fully recycled concrete

This study introduces innovative concepts for closed-loop recycling waste concrete to produce fully recycled concrete (FRC). Multiple test methods and characterization techniques were used to evaluate the physical properties and durability of four types of concrete (normal concrete, recycled aggregate concrete, recycled cement concrete and FRC). The fresh density, compressive strength, ultrasonic characteristics, chloride resistance, water adsorption properties, carbonation behaviors, and microstructure characteristics of these concretes were investigated. The water absorption behavior of FRC can be divided into three stages, with the initial stage having a water absorption rate three times that of ordinary concrete. It was found that carbonation depth varied among different concrete types, influenced by binder quality, which can affect the porosity and mechanical properties. Overall, recycled cement concrete and FRC demonstrate considerable potential for reducing carbon emissions, with total emissions of 59.152 kgCO2/m3, representing an 85% reduction compared to ordinary concrete.

Optical Target Projector: Principle of Functioning and Basic Performance Test.

Faced with measurement conditions such as high-temperature forging, strict prohibition of surface contamination, and toxic environments, using the projection point of an optical target projector (referred to as an "optical projector") as a photogrammetric target has become a necessary method of high-precision industrial photogrammetry. In connection with the current industrial demand, we have analyzed the principles of optical projectors and introduced their optical characteristics and advantages in the field of industrial photogrammetry. On this basis, a series of tests such as brightness, roundness, and so on were conducted to determine the basic properties of the optical projector. A set of performance test methods including inner coincidence accuracy and outer coincidence accuracy were proposed; the tests included industrial photogrammetry system measurement repeatability, surface measurement precision, and a comparison test with laser tracker. The test conditions used optical projection points as the photogrammetry targets. The test results showed that the coordinate measurement repeatability of the industrial photogrammetry system is 0.010 mm, and the surface measurement precision is 0.007 mm under the condition of a single optical projector station, with little difference between the results under the condition of pasting retro-reflective targets. In the process of the comparison test with laser tracker, the image quality of the black measurement object obtained is obviously inferior to other surfaces, so the analysis of the point projector is greatly affected by the color of the measured object and other conditions, which provides a reference for the measurement object and application range of the industrial photogrammetric system based on optical targets. The results demonstrate the applicability and reliability of using the optical projection point of an optical projector as target points for photogrammetry.

Report of RILEM TC 281-CCC: A critical review of the standardised testing methods to determine carbonation resistance of concrete

The chemical reaction between CO2 and a blended Portland cement concrete, referred to as carbonation, can lead to reduced performance, particularly when concrete is exposed to elevated levels of CO2 (i.e., accelerated carbonation conditions). When slight changes in concrete mix designs or testing conditions are adopted, conflicting carbonation results are often reported. The RILEM TC 281-CCC ‘Carbonation of Concrete with Supplementary Cementitious Materials’ has conducted a critical analysis of the standardised testing methodologies that are currently applied to determine carbonation resistance of concrete in different regions. There are at least 17 different standards or recommendations being actively used for this purpose, with significant differences in sample curing, pre-conditioning, carbonation exposure conditions, and methods used for determination of carbonation depth after exposure. These differences strongly influence the carbonation depths recorded and the carbonation coefficient values calculated. Considering the importance of accurately determining carbonation potential of concrete, not just for predicting their durability performance, but also for determining the amount of CO2 that concrete can re-absorb during or after its service life, it is imperative to recognise the applicability and limitations of the results obtained from different tests. This will enable researchers and practitioners to adopt the most appropriate testing methodologies to evaluate carbonation resistance, depending on the purpose of the conclusions derived from such testing (e. g. materials selection, service life prediction, CO2 capture potential).

Analisis Kualitas Instrumen Penilaian Berbasis Kelas untuk Mengukur Kompetensi Literasi Sains Peserta Didik SMA pada Materi Energi Terbarukan

The aim of this research is to analyze the quality of class-based instruments in the domains of knowledge, attitudes and skills to measure scientific literacy competency. This research uses a limited ADDIE research design consisting of Analyze, Design and Development stages. Data was collected using test and questionnaire methods. This research was tested on 30 Unesa Physics Education Study Program students. Theoretical validity results show that the assessment instrument prepared meets the valid category. The theoretical validity results were obtained from validation by 3 expert validators, namely 2 Unesa Physics Education lecturers and 1 MBI Amanatul Ummah Pacet Mojokerto teacher. Empirical validity was obtained from testing the assessment instrument on 30 active Unesa Physics Education students with a total of 15 questions. Then, the question item was declared valid with an rcount of 0.922 and an rtable of 0.361.

Assessing the Fatigue Stress Behavior of Starch Biodegradable Films with Nanoclay Using Accelerated Survival Test Methods

A destructive degradation model was applied on films made from different concentrations of starch, glycerol and nanoclay using various elongation levels as a stress variable at different stress times and stretch cycles. The log tensile quotient (logarithm of the tensile strength to the corresponding break cycle) was recorded as the response variable. The log tensile quotient increased, and the log exact break time decreased, as the elongation level increased. The treatment containing the highest starch and nanoclay and lowest glycerol content proved to be the most resistant to stress conditions and the most versatile in relation to the varying log tensile quotients, while the treatments containing the lowest nanoclay and highest glycerol contents, regardless of the starch concentration, manifested the lowest log tensile quotient at higher levels of log exact break time. According to multiple regression findings, the break cycle governed mostly the stress conditions in the degradation model, followed by the sample ID and the log exact break time. The term log tensile quotient, attempted for the first time on data concerning biodegradable films enhanced with nanoclay, seems very promising for deeper research due to its ability to retrieve predictive information from survival equations and to discriminate the difference between film structures.

Chemicals regulation and non-animal methods: displacing the gold standard.

Regulating industrial chemicals in foodstuffs and consumer products is a major aspect of protecting populations against health risks. Non-animal testing methods are an essential part of the radical change to the framework for toxicity testing that is long overdue in global economies. This paper discusses reasons why the drive to reduce animal testing for chemical safety testing is so difficult to achieve, as perceived by those who are closely involved in chemicals regulations in different capacities. Progress is slow, despite the fact that the ethico-legal conditions for a move away from animal testing are largely in place, and despite scientific arguments for a radical change in the paradigm of toxicity testing, away from reliance on animal studies. I present empirical data drawn from two studies in a European Commission context promoting non-animal methods. The aim of the paper is modest. It is to foreground the voices of those who deal with the science and regulation of chemicals on a day-to-day basis, rather than to offer a theoretical framework for what I heard from them. I offer a synthesis of the main challenges faced by non-animal alternatives, as these are perceived by people in different stakeholder groups dealing with chemicals regulation. I show where there are pockets of agreement between different stakeholders, and where the main disagreements lie. In particular there is dispute and disagreement over what counts as validation of these alternative tests, and by implication of the traditional 'gold standard' of animal testing. Finally, I suggest that the shift to non-animal methods in chemicals regulation demonstrates the need for the concept of validation to be broadened from a purely techno-scientific definition, and be more explictly understood as a demand for trust and acceptance, with more attention given to the complex social, institutional and economic settings in which it operates.

Preparation of Bi@Ho3+:TiO2/Composite Fiber Photocatalytic Materials and Hydrogen Production via Visible Light Decomposition of Water

Using electrospun nanofibers doped with TiO2 and rare-earth ion Ho3+ as the matrix, and sodium gluconate as the reducing agent, Bi(NO3)3 was reduced using hydrothermal technology to produce Bi@Ho3+:TiO2 composite fiber materials. The materials’ phase, morphology, and photoelectric properties were characterized using various analytical testing methods, including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), and transient photocurrent (IP). During the hydrothermal process, it was confirmed that Bi3+ was reduced by sodium gluconate to form pure Bi nanoparticles, which combined with Ho3+:TiO2 nanofibers to form heterojunctions. By leveraging the surface plasmon resonance (SPR) effect of metallic Bi and the abundant energy level structure and 4f electron transition properties of rare-earth Ho3+, the TiO2 nanofibers underwent dual modification, effectively enhancing the photocatalytic activity and stability of TiO2. Under visible light irradiation, the rate of hydrogen production through water decomposition reached 43.6 μmol·g−1·h−1.

Virtual Tools for Testing Autonomous Driving: A Survey and Benchmark of Simulators, Datasets, and Competitions

Traditional road testing of autonomous vehicles faces significant limitations, including long testing cycles, high costs, and substantial risks. Consequently, autonomous driving simulators and dataset-based testing methods have gained attention for their efficiency, low cost, and reduced risk. Simulators can efficiently test extreme scenarios and provide quick feedback, while datasets offer valuable real-world driving data for algorithm training and optimization. However, existing research often provides brief and limited overviews of simulators and datasets. Additionally, while the role of virtual autonomous driving competitions in advancing autonomous driving technology is recognized, comprehensive surveys on these competitions are scarce. This survey paper addresses these gaps by presenting an in-depth analysis of 22 mainstream autonomous driving simulators, focusing on their accessibility, physics engines, and rendering engines. It also compiles 35 open-source datasets, detailing key features in scenes and data-collecting sensors. Furthermore, the paper surveys 10 notable virtual competitions, highlighting essential information on the involved simulators, datasets, and tested scenarios involved. Additionally, this review analyzes the challenges in developing autonomous driving simulators, datasets, and virtual competitions. The aim is to provide researchers with a comprehensive perspective, aiding in the selection of suitable tools and resources to advance autonomous driving technology and its commercial implementation.

Improved Foucault method with double-shoot shadow grams in optical shop testing.

The lack of rapid, effective, and quantitative testing methods in the initial stages of optical processing has been identified as a significant challenge. In response, an innovative approach has been developed to enhance the Foucault knife-edge test method, integrating digital image processing and spatial geometry algorithms. This has resulted in the creation of a convenient and rapid optical testing method, which has been successfully implemented in practice. The method requires the collection of only two knife-edge shadow grams, which are then subjected to calculation. This enables the theoretical results of the knife-edge shadow gram at the focal point, and the reference results of the wavefront surface processing error of the mirror to be measured can be obtained. The method can be well applied to the testing work of optical workshops and provides a guiding solution with better performance for optical testing than the traditional knife-edge testing method.

Real-time Monitoring and Optimization of Machine Learning Intelligent Control System in Power Data Modeling Technology

In response to the problems of insufficient model accuracy and poor real-time performance in real-time monitoring and optimization of data models in traditional power systems, this paper explored them based on machine learning. It used methods such as box plots and Kalman filters to preprocess power data and used Fourier transform and long short-term memory (LSTM) network to extract data features. Based on long-term and short-term memory networks, this paper constructed a deep neural network model to process data. Recursive feature elimination method can be used for feature selection in the model, and multi-model integration method can be used for feature fusion. The experiment trained and tested the model on two datasets, IEEE 39-Bus and Pecan Street. The experimental results show that the accuracy of the paper's model in both the training and testing sets is higher than that of the convolutional neural network, decision tree, and support vector machine models in the comparative experiments, reaching 93% and 94%, respectively. The average response times in three different testing methods were 139.8ms, 151ms, and 140.6ms, respectively. The lowest daily failure rate for 30 consecutive days of work was 0%, which reflects the stability of the model; in the satisfaction survey of practitioners, the proportion of high recognition answers to each question was higher than 80%. The experimental results show that the machine learning intelligent control system has achieved good application in power data modeling technology, providing a reference for similar research in the future.

A novel large-scale direct shear apparatus considering size effects on strength of frozen coarse-grained soils

As engineering activities in cold regions expand and the application of artificial ground freezing technology in constructions grows, understanding the strength of frozen coarse-grained soils has become imminently crucial. While existing research and testing methods have provided valuable opinions into the behavior of coarse-grained materials in frozen states, there is a recognized need to enhance and expand these methods to gain a more comprehensive understanding of how size effects influence the strength of these materials. To further investigate this issue, a novel large-scale direct shear apparatus was employed to determine the shear strength of frozen coarse-grained soil materials. The apparatus features a unique design capable of accommodating square specimens with five different section lengths: 100 mm, 150 mm, 200 mm, 250 mm, and 300 mm. Depending on the maximum load requirements and budget constraints of the experiment, the equipment can provide a maximum normal stress of 5.5–50 MPa and a maximum shear stress of 3.5–30 MPa for different sample sizes, along with precise temperature control down to −30 °C. The efficacy of the device is validated through experiments conducted on frozen coarse-grained soil samples with specific particle size distributions. This study presents the technological details involved in the development of the apparatus and offers preliminary insights into the strength characteristics of frozen coarse-grained soils, highlighting the influence of size effects. The innovative features of the apparatus help the geotechnical community to comprehensively understand the strength characteristics of this complex material, thereby improving the reliability of engineering practices that involve it.

Effectiveness of Xanthan Gum-based composite in repairing cracks in reinforced concrete structures

Abstract This study investigates the enhancement of concrete slabs using a biopolymer-modified cementitious repair material (CXT) composed of Ordinary Portland Cement, Xanthan Gum, and Tartaric Acid Powder. The innovative formulation of CXT aims to improve the mechanical properties of repaired concrete structures. Experimental results demonstrate that CXT significantly enhances mechanical properties such as the load-bearing capacity of concrete slabs. Non-destructive testing methods, including the Rebound Hammer test and Ultrasonic Pulse Velocity (UPV), as well as destructive testing methods, were employed to evaluate the performance of CXT in repairing cracks. The study highlights the improved load-bearing capacity and structural integrity of CXT-repaired slabs, contributing to increased longevity and reduced maintenance costs of concrete structures. Furthermore, the sustainability metrics of CXT, including Process Mass Intensity (PMI), Energy Intensity (EI), Environmental Factor (E-Factor), and Reaction Mass Efficiency (RME), are evaluated, illustrating its cost-effectiveness and environmental benefits. This comprehensive approach underscores the potential of CXT as a durable and sustainable repair material for concrete infrastructure.

Evolution characteristic and mechanism of microstructure, hydraulic and mechanical behaviors of sandstone treated by acid-rock reaction: Application of in-situ leaching of uranium deposits

The main difficulty in understanding the effects of chemical-physical composite stimulation for low-permeability sandstone-type uranium deposits is clarifying the influence of acidification on pore response mechanism and permeability-mechanical properties evolution during loading-deformation-failure process. Therefore, the acid-rock reaction experiment was first performed, the multiple testing methods (X-ray Diffraction, thin-section identification, high-pressure mercury intrusion porosimetry, stress-seepage coupling experiment) were then conducted, the evolution laws and mechanisms of reservoir physical characteristics after acidification were finally clarified. Results show that after the acid-rock reaction, the contents of calcite, feldspar and kaolinite of samples are decreased and the quartz content is increased, the permeabilities of samples are all promoted, the peak strength, elastic modulus, and shear modulus of samples are reduced and the Poisson’s ratio is raised. The acid-rock reaction changes the energy storage performance and promotes the plasticization of samples. It is suggested to adopt a lower sulfuric acid concentration (2 g/L) and longer reaction time (>45 d) for the ISL of uranium deposits. This work has important theoretical and practical significance for an in-depth understanding of the enhanced mining of low-permeability sandstone-type uranium deposits.

Sound Metric Proximity Hearing App

Globally, hearing impairment affects over 466 million people, creating barriers to accessing audiometric testing and timely diagnosis. Conventional methods often prove challenging to access, especially for people with limited resources or any other disadvantages. The proposed innovative "Sound Metric Proximity Hearing App" aims to revolutionize auditory health through mobile technology. Utilizing advanced techniques such as frequency-specific sound generation, individual ear sound production, and obstacle detection, the app provides comprehensive hearing tests through a user-friendly platform. The application is developed using React Native for the frontend and Django for the backend. It integrates seamlessly with mobile devices and databases, ensuring efficient and reliable performance. With simple result export and tools for early detection, the application enhances the accessibility and efficiency in hearing assessments. It bridges gaps in traditional testing methods, empowering users to proactively manage their auditory health. The "Sound Metric Proximity Hearing App" addresses the essential need for accessible, efficient hearing tests, making a positive impact on global auditory health. Through its innovative approach, the app aims to reduce the stigma associated with hearing loss and promote early intervention. By providing a convenient tool for educators, the app supports classroom management and improves learning environments. With its potential to reach unprivileged people and enhance awareness, the proposed sound metric application is devised to contribute significantly to global auditory health.

LP-22 Regulatory and industrial acceptance of non-animal pyrogen test methods in India: challenges and opportunities

LP-22 Regulatory and industrial acceptance of non-animal pyrogen test methods in India: challenges and opportunities

Efficient protein extraction for assessing food allergy risk in complex alternative protein matrices

Allergy to novel food proteins, due to diverse ingredients and innovative food processing technologies employed to achieve desired functional properties, is a major safety concern. Current allergy testing methods (ELISA and mass spectrometry) depend on high-quality protein extracts, meaning existing methods are often tailored to specific matrices. Therefore, a more efficient and general protein extraction method is desirable for comprehensive allergy risk assessment. Here, we developed a highly efficient and reproducible protein extraction method which achieved at least 80 % efficiency across several food matrices. Proteomics analysis of a plant-based meat using our optimized extraction method showed that higher extraction efficiency improved reproducibility of identified proteins. Moreover, higher protein extraction efficiency resulted in increased abundances of individual allergenic proteins. This underscores the relevance of our method for more accurate measurements of allergenic protein concentrations in allergy risk assessments.

P01-42 In vitro test methods and petroleum UVCB substances: critical review of dosing methods

P01-42 In vitro test methods and petroleum UVCB substances: critical review of dosing methods

Interface stiffness identification of rough and weak bonded interface using developed ultrasonic reflection phase derivative spectrum

The thickness and interface roughness of coatings both affect the interface bonded quality. Existed ultrasonic testing methods based on traditional phase screen approximation or spring model assumption are difficult to simultaneously identify the interface roughness and stiffness of coating. This paper, a new method for integrated identifying coating thickness, interface roughness, and interface stiffness using developed ultrasonic reflection phase derivative spectrum (URPDS) is proposed. A phase-screen-approximated spring-model (PSASM) for ultrasound vertically propagating into rough and weak bonded interface is constructed. On basis of PSASM, a URPDS of coating/substrate structure is developed for identifying the interface stiffness and other parameters of coated parts. Cross-correlation analysis is used to eliminate the phase deviation of URPDS introduced by reference signal and initial phase of tested signal. Sensitivity analysis is used to determine the high-sensitivity regions of URPDS to interface roughness and interface stiffness. Genetic algorithm optimization is used to achieve integrated identification of coating thickness, interface roughness, and interface stiffness. The rationality of PSASM is verified through numerical simulation using a series of coating/substrate models with rough and weak bonded interface, and the relationship between the high-sensitivity regions and the high-precision measurement ranges of interface roughness Rq and interface stiffness Kn is clarified. Ultrasonic experiments are implemented on Nickel-coating samples and coated parts using plane wave probe. The coating thickness, interface roughness, and interface stiffness could be identified accurately, which shows that the proposed URPDS method can identify the interface stiffness of rough contacted dissimilar media or coated parts with rough interface.

Multi-Technique Characterization of Cartonnage and Linen Samples of an Egyptian Mummy from the Roman Period

The historical and cultural significance of artistic works and archaeological artifacts underscores the imperative use of non-destructive testing methods in cultural heritage objects. Analyzing pigments in artwork poses a specific analytical challenge that demands a combination of various techniques to accurately determine chemical compositions. In this context, our work focused on the multi-analytical characterization of samples derived from fragments of a Roman-era Egyptian mummy named Kherima, dating back to around 200 AD. To identify the layers and elemental composition of the pigments used in the decoration, various techniques were employed: X-ray microfluorescence (µXRF), X-ray diffraction (XRD), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), high-resolution optical microscopy (OM), and X-ray computed microtomography (microCT). This multi-analytical approach facilitated the identification of the original pigments in the analyzed mummy fragments, along with insights into the materials used in the ground layer and the techniques applied in artifact manufacturing, indicating their accordance with the historical period and region to which they originally belonged.