Common Test Methods Research Articles

Lithium Plating Detection Methods in Lithium-Ion Batteries

Lithium-ion batteries provide a low-cost, long cycle-life and high energy density solution to the expediting energy requirement of the automotive industry. There is a growing need of fast charging batteries for commercial application. However, large charging currents may cause Lithium plating which describes the deposition of metallic Lithium at the anode surface. It takes place at conditions of high currents and/or low temperatures because of kinetic limitations. The main reason behind plating is the slow solid-state diffusion of Lithium ions inside the active material. If the anode surface potential falls below 0 V versus Li/Li+, the formation of metallic Lithium is thermodynamically feasible. To avoid or reduce the amount Lithium plating, it is essential to detect its onset during a charging event.Determination of accurate Lithium plating curve is crucial in estimating the boundary conditions for battery operation without compromising life and safety. There are various data analysis methods involved in deriving the Lithium plating curve: anode potential using a three-electrode cell, variation of relaxation voltage after charging (dV/dt), variation of accumulated charge with voltage (dQ/dV) and coulombic efficiency of charge/discharge with %SOC (state of charge) are more commonly employed techniques. In addition to these methods, estimation of its occurrence is typically underpinned by electrochemical models where the negative (anode) electrode potential is expressed by a set of partial differential equations based on the electrochemical and physical properties of the battery components such as the electrodes and electrolyte. The present paper reviews the common test methods and analysis that are currently utilized in Lithium plating determination. Knowledge gaps are identified, and recommendations are made for the future development in the determination and verification of Lithium plating curve in terms of modelling and analysis.

Biomarker testing in non-small cell lung cancer in routine care: Analysis of the first 3,717 patients in the German prospective, observational, nation-wide CRISP Registry (AIO-TRK-0315)

ObjectivesAn increasing number of treatment-determining biomarkers has been identified in non-small cell lung cancer (NSCLC) and molecular testing is recommended to enable optimal individualized treatment. However, data on implementation of these recommendations in the “real-world” setting are scarce. This study presents comprehensive details on the frequency, methodology and results of biomarker testing of advanced NSCLC in Germany. Patients and methodsThis analysis included 3,717 patients with advanced NSCLC (2,921 non-squamous; 796 squamous), recruited into the CRISP registry at start of systemic therapy by 150 German sites between December 2015 and June 2019. Evaluated were the molecular biomarkers EGFR, ALK, ROS1, BRAF, KRAS, MET, TP53, RET, HER2, as well as expression of PD-L1. ResultsIn total, 90.5 % of the patients were tested for biomarkers. Testing rates were 92.2 % (non-squamous), 70.7 % (squamous) and increased from 83.2 % in 2015/16 to 94.2% in 2019. Overall testing rates for EGFR, ALK, ROS1, and BRAF were 72.5 %, 74.5 %, 66.1 %, and 53.0 %, respectively (non-squamous). Testing rates for PD-L1 expression were 64.5 % (non-squamous), and 58.5 % (squamous). The most common testing methods were immunohistochemistry (68.5 % non-squamous, 58.3 % squamous), and next-generation sequencing (38.7 % non-squamous, 14.4 % squamous). Reasons for not testing were insufficient tumor material or lack of guideline recommendations (squamous). No alteration was found in 37.8 % (non-squamous), and 57.9 % (squamous), respectively. Most common alterations in non-squamous tumors (all patients/all patients tested for the respective biomarker): KRAS (17.3 %/39.2 %), TP53 (14.1 %/51.4 %), and EGFR (11.0 %/15.1 %); in squamous tumors: TP53 (7.0 %/69.1 %), MET (1.5 %/11.1 %), and EGFR (1.1 %/4.4 %). Median PFS (non-squamous) was 8.7 months (95 % CI 7.4–10.4) with druggable EGFR mutation, and 8.0 months (95 % CI 3.9–9.2) with druggable ALK alterations. ConclusionTesting rates in Germany are high nationwide and acceptable in international comparison, but still leave out a significant portion of patients, who could potentially benefit. Thus, specific measures are needed to increase implementation.

A Synthesis on the Effects of Two Commercial Recycled Plastics on the Properties of Bitumen and Asphalt

The desire to develop sustainable infrastructure, including pavement structures and materials, is ever increasing in recent times. One opportunity is to partially replace high-cost bituminous binder with low-cost recycled plastic in asphalt mixtures. This synthesis combines the various research efforts to understand the effects of two commercially available recycled plastics, known as MR6 and MR10, on bituminous binders and asphalt mixtures. Using common test methods from the United Kingdom, the United States and Australia, generally consistent and significant effects were observed in various base bitumen grades and various common asphalt mixture types. Binder resistance to flow and binder elasticity both increased significantly and were associated with the three to four grade increases under the Performing Grading system. Similarly, mixture stiffness and mixture resistance to deformation increased significantly, while crack resistance and moisture damage resistance were not significantly affected. The effects of MR6 and MR10 were generally similar to the effects associated with conventional polymer modification of asphalt binders and asphalt mixtures, particularly those effects associated with plastomeric polymers.

Experimental evaluation of freeze-thaw durability of pervious concrete

The ASTM C666 procedure is the common test method used for evaluating the freeze-thaw durability of conventional concrete, and it has been adapted for evaluating the freeze-thaw resistance of pervious concrete; however, it is argued the test method does not represent the field conditions of neither conventional nor pervious concrete. This study mainly focused on an experimental program to evaluate the freeze-thaw durability of pervious concrete specimens using the JC446-91 test method, which measures the change in compressive strength and mass after exposure to freeze-thaw cycles, as an alternative for ASTM C666. Various parameters affecting the freeze-thaw durability of pervious concrete, namely water to cement ratio (W/C), air entrainment, inclusion of sand, and coarse aggregate size were experimentally examined, and the results were evaluated using statistical analysis. It was observed that replacing 8% of coarse aggregate with sand and using a higher W/C resulted in higher strength and an improvement in the freeze-thaw durability. Although the positive effect of air-entraining admixture (AEA) on freeze-thaw durability of pervious concrete has been manifested by previous researchers, it was not clearly observed in this study. Also, change in coarse aggregate size did not significantly affect the strength and freeze-thaw durability of pervious concrete. This study revealed that the conditions and number of cycles used in JC446-91 were inadequate to evaluate the freeze-thaw durability of pervious concrete, especially for strong mixes. Therefore, considering the criticisms against ASTM C666 in representing field conditions of pervious concrete, more compatible and realistic test methods are required to evaluate the freeze-thaw durability of pervious concrete.

Nondestructive Detection of Gaps between Railway Track Slabs and Soil Foundation Using Leaked Air Waves

Gaps generated underneath railway track slabs may cause unstable conditions. Such gaps can form because of different reasons, including settlement of soft soil, unsuitable construction of a concrete slab on loosely compacted soil, and drastic stiffness change in a transition zone between the bridge deck and embankment. The gaps underneath railway track slabs are not easily detectable by common nondestructive test methods. A nondestructive test (NDT) based on a wavelet time–frequency concept is proposed for the practical purpose of detecting gaps under track slabs. The method uses a microphone sensor to catch leaked Rayleigh acoustic waves in the air and an accelerometer to measure surface Rayleigh waves on the slab. In order to investigate the possibility of developing the test system, a finite element analysis (FEA) was performed to simulate Rayleigh wave generation on the concrete surface and in the air. A test system module composed of a microphone and an accelerometer, data acquisition system (DAQ), and an analyzer program was also assembled for a small backyard pilot test. It was verified that the new NDT test system could be successfully adapted for detecting gaps underneath railway track slabs and track bed soil.

Divergence between Performance in the Field and Laboratory Test Results for Alkali-Silica Reaction

The most common test methods used to evaluate alkali-silica reaction (ASR) are the concrete prism test (CPT) and the accelerated mortar bar test (AMBT). However, these tests were not found to be entirely reliable in predicting the performance of concrete under field conditions, especially when supplementary cementitious materials (SCMs) are used. Recently, two new test methods, the miniature concrete prism test (MCPT) and the concrete cylinder test (CCT), have been proposed but still need to be benchmarked with results from outdoor exposed blocks. In this paper, the results from the MCPT, CCT, CPT and exposed blocks are compared and their ability to properly evaluate the expected behavior of these mixtures in service with regard to ASR is discussed. Here, the results of mixtures made with four reactive aggregates: Spratt, Placitas (coarse aggregates), Wright, and Jobe (fine aggregates) and SCMs (fly ashes Classes F or C, slag cement, or silica fume) at different levels of cement replacement or lithium nitrate are presented. For these mixtures, only the MCPT was capable of properly classifying the efficiency of the ASR preventive measures, as compared with the long-term results obtained from the exposed blocks.

Dynamic tensile process of blended fabric using finite element method

PurposeTensile property is one basic mechanics performance of the fabric. In general, not only the tensile values of the fabric are needed, but also the dynamic changing process under the tension is also needed. However, the dynamic tensile process cannot be included in the common testing methods by using the instruments after fabric weaving.Design/methodology/approachBy choosing the weft yarn and warp yarn in the fabric as the minimum modeling unit, 1:1 finite element model of the whole woven fabrics was built by using AutoCAD software according to the measured geometric parameters of the fabrics and mechanical parameters of yarns. Then, the fabric dynamic tensile process was simulated by using the ANSYS software. The stress–strain curve along the warp direction and shrinkage rate curve along the weft direction of the fabrics were simulated. Meanwhile, simulation results were verified by comparing to the testing results.FindingsIt is shown that there are four stages during the fabric tensile fracture process along the warp direction under the tension. The first stage is fabric elastic deformation. The second stage is fabric yield deformation, and the change rate of stress begins to slow down. The third stage is fiber breaking, and the change of stress fluctuates since the breaking time of the fibers is different. The fourth stage is fabric breaking.Originality/valueIn this paper, the dynamic tensile process of blended woven fabrics was studied by using finite element method. Although there are differences between the simulation results and experimental testing results, the overall tendency of simulation results is the same as the experimental testing results.

Influence Analysis of Narrowband Random Sweep Range Setup in Mixed Mode Vibration Test

AbstractSweeping narrowband random on broadband random (RoR) is a common vibration test method. However, different vibration controllers have different definitions on a sweep frequency range of narrowband. Some controllers define the sweep range by the central frequency of the narrowband, as well as the others by the left and right boundaries of the narrowband bandwidth, respectively. The difference between these two setups may have significant influence on the response of the test specimen when its natural frequency is adjacent to the sweep range, which may lead to different test results. This paper studies the different responses of a single-degree-of-freedom (SDOF) system with different Q between the two setups when conducting RoR tests. Simulating and experimental results are also presented. The conclusion is that the sweep range setup can result to unneglectable test difference and the test operators should be aware of it when setting up the test profile.

Building fault detection data to aid diagnostic algorithm creation and performance testing

It is estimated that approximately 4–5% of national energy consumption can be saved through corrections to existing commercial building controls infrastructure and resulting improvements to efficiency. Correspondingly, automated fault detection and diagnostics (FDD) algorithms are designed to identify the presence of operational faults and their root causes. A diversity of techniques is used for FDD spanning physical models, black box, and rule-based approaches. A persistent challenge has been the lack of common datasets and test methods to benchmark their performance accuracy. This article presents a first of its kind public dataset with ground-truth data on the presence and absence of building faults. This dataset spans a range of seasons and operational conditions and encompasses multiple building system types. It contains information on fault severity, as well as data points reflective of the measurements in building control systems that FDD algorithms typically have access to. The data were created using simulation models as well as experimental test facilities, and will be expanded over time.

Porous LaFeO3 microspheres decorated with Au nanoparticles for superior formaldehyde gas-sensing performances

Formaldehyde is one of the most serious pollutants of volatile organic compounds in indoor environment. The monitoring of formaldehyde concentration of the indoor environment has become an urgent issue in modern society. In this paper, a facile wet-chemical method was used to prepare the catalytic Au nanoparticle-functionalized LaFeO3 porous microspheres with high formaldehyde (HCHO)-sensing performances. The Au/LaFeO3 nanocomposites were characterized by several common testing methods, such as XRD, SEM, EDS, TEM, and XPS. The results showed that Au nanoparticles were uniformly attached to the surface of porous LaFeO3 microspheres. And the gas-sensing experiments showed that Au nanoparticle-functionalized porous LaFeO3 microspheres showed high response even at low concentration (1 ppm), good selectivity, good reproducibility, and ultrafast response (2 s) and recovery (9 s) to formaldehyde. Therefore, the successful preparation of Au/LaFeO3 nanocomposites is expected to be used in the rapid detection of formaldehyde gas.

Quantitative peel test for thin films/layers based on a coupled parametric and statistical study

The adhesion strength of thin films is critical to the durability of micro and nanofabricated devices. However, current testing methods are imprecise and do not produce quantitative results necessary for design specifications. The most common testing methods involve the manual application and removal of unspecified tape. This overcome many of the challenges of connecting to thin films to test their adhesion properties but different tapes, variation in manual application, and poorly controlled removal of tape can result in wide variation in resultant forces. Furthermore, the most common tests result in a qualitative ranking of film survival, not a measurement with scientific units. This paper presents a study into application and peeling parameters that can cause variation in the peeling force generated by tapes. The results of this study were then used to design a test methodology that would control the key parameters and produced repeatable quantitative measurements. Testing using the resulting method showed significant improvement over more standard methods, producing measured results with reduced variation. The new method was tested on peeling a layer of paint from a PTFE backing and was found to be sensitive enough to register variation in force due to differing peeling mechanisms within a single test.

PCN39 TREATMENT PATTERNS, MINIMAL RESIDUAL DISEASE (MRD) TESTING PATTERNS AND CLINICAL OUTCOMES IN PATIENTS WITH ACUTE LYMPHOBLASTIC LEUKEMIA (ALL): A PATIENT CHART REVIEW IN BELGIUM, GREECE AND SWITZERLAND

Survival rates remain poor for patients with B-precursor ALL, especially for those in whom MRD is not eradicated early in treatment. This study aims to further understand treatment patterns, MRD testing patterns and outcomes in adult patients with B-precursor ALL, to aid real-world decision-making. This descriptive, retrospective medical chart review collected patient-level data in 2018. Patients needed to have ≥1 MRD test during front-line treatment (induction/consolidation) and were followed from diagnosis until death, loss to follow-up or end of observation period. Data were stratified by MRD status at first MRD test. Eighty-two patients were included (median age 44 years, 23% Philadelphia chromosome+; median follow-up 25.4 months; MRD-positive: n=17, MRD-negative: n=50, MRD result unknown: n=15 [median follow-up: 31.7, 27.2 and 12.0 months, respectively]). Most patients received HyperCVAD (32%) or HOVON (26%) front-line treatment protocols; 22% received allogeneic stem cell transplantation. Overall, 76% of patients were hospitalized (mean 1.07 hospitalization/month). Complete hematological response (CRh) occurred in 77% of patients (77% of MRD-positive, 94% of MRD-negative patients). Median relapse-free survival from CRh was 32.7 months (MRD-positive:11.7 months; MRD-negative: 33.2 months). Median overall survival from diagnosis was 28.9 months (MRD-positive: 15.3 months; MRD-negative: not reached); 71%, 60% and 39% were alive at 1, 2 and 5 years. Most patients (88%) were MRD tested during induction; testing rates considerably decreased thereafter (39% during consolidation) and timepoints varied. Flow cytometry (60%) and PCR (26%) were the most common MRD testing methods. ALL represents clinical and economic burden. Our findings suggest MRD-positive patients have worse prognosis than MRD-negative patients and highlight the clinical relevance of MRD testing outside of clinical trials. Given the prognostic impact of MRD status, it is important to ensure MRD is tested throughout treatment, to ensure appropriate patient management.

Active Contour Model for Brain MR Tumor Segmentation and Volume Estimation

Brain MR tumor segmentation and estimation of volume is a critical task in medical applications. Brain tumors are analyzed by the common test method known as magnetic resonance imaging (MRI) which provides a detail image of brain. The proposed work involves detection of tumor in brain using deep learning based active contour model. Segmentation is the main objective of the proposed work for achieving detailed information about the tumor and accurate volume estimation to detect the size of the tumor. The Euclidean similarity factor (ESF) is used for considering the spatial distances and intensity differences of the region there by preserving all the fine details of the image. 3D convolutional neural network (3DCNN) is used for extracting the features and segmentation to identify the tumor location in the brain. Finally, shoelace method is used to estimate the volume of the tumor, and it provides treatment planning, surgical methods, estimation of dose, etc. The simulation results in this suggested approach could attain effective performance as compared with the existing approaches.

656P - Middle East & North Africa registry to characterize RAS mutation status and tumour specifications in recently diagnosed patients with metastatic colorectal cancer (MORE-RAS Study)

BackgroundRAS mutational status is an essential criterion to guide first-line treatment in metastatic colorectal cancer (mCRC). MORE-RAS was a multicenter, multicountry, observational, ambispective (retrospective + prospective) study conducted in the Middle East and North Africa (MENA) region to assess RAS testing practices and tumor characteristics in newly diagnosed patients (pts) with mCRC. Results of the retrospective analysis are presented here. MethodsEligible pts included adults aged ≥18 with mCRC who had already initiated first-line therapy, had at least 1 post-baseline visit for disease evaluation, and had available survival data. Pts with incomplete and unavailable data or presence of other coexisting malignancies were excluded. Data from eligible pts were retrospectively analysed 2 years back from the day of patient consent. ResultsA total of 495 pts (median age: 57 y) were enrolled; majority were male (55.6%), with adenocarcinoma histology, stage IV disease (86.8%) and left-sided tumors (79%). Primary tumor site was sigmoid (40.9%), followed by rectal (26.1%), ascending (17.2%), descending (12.1%), and transverse (3.8%) colon. RAS testing was requested in 417 (78%) pts; reasons for not prescribing included test unavailability, financial/medical decision, or other. Testing samples were mostly paraffin-embedded (91.7%) primary tumors (92.5%); sequencing was the most common test method used. RAS testing found that 33.9% of tumors harbored mutations and 66.1% carried wild-type (WT) sequences. The most common mutation was KRAS (94.1%), occurring largely in Exon2-Codon12 (70.5%). RAS testing was typically prescribed after initiation of first-line treatment, significantly more in pts with stage IV disease (p<0.005), resulted in addition of targeted therapy (41.8% anti EGFR, 30.2% anti VEGF) in WT mCRC, and significantly impacted treatment strategy of left-sided tumors (p=0.037). ConclusionsRAS testing for mCRC in the MENA region was often performed after first-line treatment. The dominance of WT RAS in this region is distinct from the mutational pattern reported in Western countries. Legal entity responsible for the studyAmgen. FundingAmgen. DisclosureM. Oukkal: Advisory / Consultancy, Speaker Bureau / Expert testimony: Amgen; Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self): Roche; Advisory / Consultancy: Novartis; Advisory / Consultancy: Pfizer; Speaker Bureau / Expert testimony: Bayer; Speaker Bureau / Expert testimony: Ipsen. H. Mahfouf: Advisory / Consultancy, Speaker Bureau / Expert testimony: Amgen; Advisory / Consultancy, Speaker Bureau / Expert testimony: Roche; Advisory / Consultancy, Speaker Bureau / Expert testimony: Merck; Advisory / Consultancy, Speaker Bureau / Expert testimony: Bayer; Advisory / Consultancy: Ipsen. A. Ouamer: Full / Part-time employment: Amgen. L. Bashir: Full / Part-time employment: Amgen. All other authors have declared no conflicts of interest.

A Systematic Review and Guide to Mechanical Testing for Articular Cartilage Tissue Engineering.

Articular cartilage is integral to the mechanical function of many joints in the body. When injured, cartilage lacks the capacity to self-heal, and thus, therapies and replacements have been developed in recent decades to treat damaged cartilage. Given that the primary function of articular cartilage is mechanical in nature, rigorous physical evaluation of cartilage tissues undergoing treatment and cartilage constructs intended for replacement is an absolute necessity. With the large number of groups developing cartilage tissue engineering strategies, however, a variety of mechanical testing protocols have been reported in the literature. This lack of consensus in testing methods makes comparison between studies difficult at times, and can lead to misinterpretation of data relative to native tissue. Therefore, the purpose of this study was to systematically review mechanical testing of articular cartilage and cartilage repair constructs over the past 10 years (January 2009-December 2018), to highlight the most common testing configurations, and to identify key testing parameters. For the most common tests, key parameters identified in this systematic review were validated by characterizing both cartilage tissue and hydrogels commonly used in cartilage tissue engineering. Our findings show that compression testing was the most common test performed (80.2%; 158/197), followed by evaluation of frictional properties (18.8%; 37/197). Upon further review of those studies performing compression testing, the various modes (ramp, stress relaxation, creep, dynamic) and testing configurations (unconfined, confined, in situ) are described and systematically reviewed for parameters, including strain rate, equilibrium time, and maximum strain. This systematic analysis revealed considerable variability in testing methods. Our validation testing studies showed that such variations in testing criteria could have large implications on reported outcome parameters (e.g., modulus) and the interpretation of findings from these studies. This analysis is carried out for all common testing methods, followed by a discussion of less common trends and directions in the mechanical evaluation of cartilage tissues and constructs. Overall, this work may serve as a guide for cartilage tissue engineers seeking to rigorously evaluate the physical properties of their novel treatment strategies. Impact Statement Articular cartilage tissue engineering has made significant strides with regard to treatments and replacements for injured tissue. The evaluation of these approaches typically involves mechanical testing, yet the plethora of testing techniques makes comparisons between studies difficult, and often leads to misinterpretation of data compared with native tissue. This study serves as a guide for the mechanical testing of cartilage tissues and constructs, highlighting recent trends in test conditions and validating these common procedures. Cartilage tissue engineers, especially those unfamiliar with mechanical testing protocols, will benefit from this study in their quest to physically evaluate novel treatment and regeneration approaches.

Shear strength of cement-treated marine clay under triaxial and plane strain conditions

Conventional triaxial compression and unconfined compressive strength tests are the most common testing methods used in the laboratory to determine the shear strength of soil. These tests employ the axisymmetric condition for testing. However, several geotechnical problems in the field can be approximated as plane strain (PS) problems. Hence, testing under PS condition would better represent such field conditions. PS testing has been widely performed on natural soils in the past. However, PS testing on cement-treated clays has not been reported in the literature. This paper attempts to explore the PS behaviour of cement-treated marine clays. A comparison of the strength behaviour of cement-treated clays under PS and triaxial tests has also been presented in this paper.

A methodology for deriving the sensitivity of pooled testing, based on viral load progression and pooling dilution

BackgroundPooled testing, in which biological specimens from multiple subjects are combined into a testing pool and tested via a single test, is a common testing method for both surveillance and screening activities. The sensitivity of pooled testing for various pool sizes is an essential input for surveillance and screening optimization, including testing pool design. However, clinical data on test sensitivity values for different pool sizes are limited, and do not provide a functional relationship between test sensitivity and pool size. We develop a novel methodology to accurately compute the sensitivity of pooled testing, while accounting for viral load progression and pooling dilution. We demonstrate our methodology on the nucleic acid amplification testing (NAT) technology for the human immunodeficiency virus (HIV).MethodsOur methodology integrates mathematical models of viral load progression and pooling dilution to derive test sensitivity values for various pool sizes. This methodology derives the conditional test sensitivity, conditioned on the number of infected specimens in a pool, and uses the law of total probability, along with higher dimensional integrals, to derive pooled test sensitivity values. We also develop a highly accurate and easy-to-compute approximation function for pooled test sensitivity of the HIV ULTRIO Plus NAT Assay. We calibrate model parameters using published efficacy data for the HIV ULTRIO Plus NAT Assay, and clinical data on viral RNA load progression in HIV-infected patients, and use this methodology to derive and validate the sensitivity of the HIV ULTRIO Plus Assay for various pool sizes.ResultsWe demonstrate the value of this methodology through optimal testing pool design for HIV prevalence estimation in Sub-Saharan Africa. This case study indicates that the optimal testing pool design is highly efficient, and outperforms a benchmark pool design.ConclusionsThe proposed methodology accounts for both viral load progression and pooling dilution, and is computationally tractable. We calibrate this model for the HIV ULTRIO Plus NAT Assay, show that it provides highly accurate sensitivity estimates for various pool sizes, and, thus, yields efficient testing pool design for HIV prevalence estimation. Our model is generic, and can be calibrated for other infections.

Fracture properties of asphalt concrete under various displacement conditions and temperatures

Fracture mechanics has been widely applied to asphalt concrete (AC) materials to evaluate the cracking potential of AC pavements under traffic and thermal loadings. While AC materials behave as quasi-brittle at low temperature and high loading rate, its behavior becomes more viscous as temperature increases and/or loading rate decreases. Considerable fracture tests have been developed to capture the fracture properties of AC materials; however, fracture properties may be misinterpreted when using various fracture tests, especially in bending-mode. This would result in an erroneous characterization of AC cracking potential, which leads to a misestimate of pavement service life. The objective of this study is to investigate common fracture test methods for the AC materials, compare the fracture energies from various displacement measurements to capture true fracture property, and examine the effect of temperature on fracture energy and Flexibility Index (FI). Fracture energy from the semi-circular bending (SCB) geometry was compared to that from the disk-shaped compact tension (DCT) test. The effect of misinterpretation of test results on fracture energies was investigated. This study also suggests a proper method to capture fracture properties from the SCB test using the basic understanding of work and energy concepts in physics. The effects of test temperature on (1) fracture energy values, (2) FI, and (3) the overall ability to discriminate the cracking potential of AC mixtures are presented. Results show that while the crack characteristics can be captured more reasonably with a Load-Crack Mouth Opening Displacement (CMOD) curve, the fracture energy is better obtained using load-Load Line Displacement (LLD) curve. Moreover, performing fracture tests at a relatively higher temperature increases the ability to distinguish between various AC mixtures’ cracking potential.

Microwave open-ended waveguide for detection and characterisation of FBHs in coated GFRP pipes

Accessing to glass fibre reinforcement plastic (GFRP) pipes in the on-line process is often limited to one side. To detect an internal defect of coated GFRP pipe, common non-destructive testing (NDT) methods such as eddy current testing and thermography are not effective because GFRP pipes are not conductive and their coating prevents heat transfer to the inner section of the material. Moreover, the curvature of GFRP pipes introduces lift-off variation, which is the primary challenge for NDT methods using C-scan technique; e.g., ultrasonic. This work proposes a novel microwave NDT application to detect and characterise internal defect; i.e., flat-bottom hole (FBH) in coated GFRP pipes. Initially, responses of four FBH areas obtained by microwave open-ended waveguide probe are analysed using principal component analysis (PCA) to reveal FBH defect and eliminate the pipe curvature influence. Following that, synthetic aperture radar (SAR) tomography images are produced to select the corresponding principal component and verify the location of FBHs. Finally, FBHs are evaluated using PC feature and SAR tomography including time-of-flight feature. The results show that the proposed method can clearly reveal the area of FBHs. Moreover, depths of FBHs are characterised by analysing the time-of-flight feature of background-subtracted responses.

Influence of local epidemiology on the performance of common colistin drug susceptibility testing methods

ObjectivesTo determine the influence of local spread of clonal strains and testing of follow-up isolates on categorical (CA) and essential agreement rates (EA) of common colistin (COL) drug susceptibility testing methods with the broth microdilution (BMD) reference method.MethodsCOL MICs were determined for 178 bacterial isolates (Enterobacteriaceae, n = 97; Pseudomonas aeruginosa, n = 81) collected within one year from 64 patients by BMD according to ISO standard 20776–1 (reference method), the SensiTest BMD panel (ST), agar dilution (AD), the VITEK 2 instrument, and gradient diffusion (GD) using antibiotic strips of two and Muller-Hinton agar plates of three manufacturers. CA and EA with BMD were calculated for all isolates and compared to the subset of 68 unique isolates.ResultsCA ranges were 79.4% to 94.1% for the unique isolateq panel and 89.9% to 96.1% for all tested isolates. EA ranges were 64.7% to 86.8% and 67.4% to 91.0%, respectively. In both panels, EA for all GD assays was lower than 90%. Both lower and higher EA values ranging from—18.3% (MTS on BD agar) to + 6.3% (AD, Vitek 2) were observed in the full one-year sample. Acquisition of colistin resistance under therapy was observed for 3 patients.Conclusionsi) Repeat testing and local spread of clonal strains can positively or negatively affect CA and EA, ii) CA is more robust towards local influences than EA, iii) EA of GD and AD methods for COL with the reference BMD method is insufficient.