Current Testing Research Articles

Designs and appropriate choices for diagnostic test accuracy study

Diagnostic tests are indispensable tools in clinical practice and are rigorously evaluated through scientifically designed accuracy studies before the clinical practice. The accuracy of these tests directly affects the correctness of the diagnosis and the rationality of treatment decisions. This article introduces the types of designs and their characteristics used in diagnostic test accuracy studies, including single-group studies, diagnostic case-control studies, single-group paired studies, and parallel-group studies. It recommends appropriate design types based on the research question stage, the diagnostic test's role in the clinical diagnostic pathway, and the actual clinical application scenario to provide suggestions for further standardizing the design of current clinical diagnostic test accuracy research. This article may help clinical researchers better understand and choose the appropriate type of diagnostic test accuracy study design to improve diagnostic test accuracy research quality.

Development of a gearbox test rig to evaluate the impact of oil formulations on churning and friction losses

From large industrial to small high-speed transmission for electric vehicles, there is a growing interest in reducing the power losses on gearboxes. Hydrodynamic losses are especially relevant on high-speed gearboxes. On electric cars, the gearbox lubricant also works as a cooling fluid for the motor, which brings new challenges as performance under an electrified environment, thermal and electrical conductivity, corrosion protection etc. Most current test rigs use the torque difference between gearbox output and input to calculate the power losses. This work, uses the instantaneous deceleration on a small gearbox to obtain the no-load depending on power losses. Due to its simplicity, the proposed method has the potential to be applied to actual transmissions with very simple sensors and without the need for significant intervention on the actual equipment. The experimental results showed increased churning power losses with the immersion depth and oil viscosity. With the tested transmission oils, the churning losses showed to depend on rotational speed by a power of three, as predicted by the ISO model. The influence of oil viscosity was less evident. Reducing viscosity 2.5 times showed only around 25% reduction in the calculated churning losses. In opposition to the tested transmission oils, a low-viscosity oil with Friction Modifier additives reduced the power losses with the consecutive larger volumes of sump oil, such unexpected result can be explained by the beneficial effect of the oil FM additives.

MnO2 Nanowire Thin Mesh With Enhanced Mass Transfer as Hydroxide Exchange Membrane Fuel Cell Cathode

AbstractHydroxide exchange membrane fuel cells (HEMFCs) are promising due to the potential use of nonprecious metal catalysts. However, the performance of HEMFCs based on nonprecious catalysts is still unsatisfactory, and one reason for this is hindered mass transfer in the catalyst layer. In this study, we employ a hydrothermal method to grow in situ a MnO2 nanowire thin mesh (NTM) catalytic layer on the gas diffusion electrode. The HEMFC prepared with MnO2 NTM cathode achieves a peak power density of 425 mW cm−2, surpassing the performance of the HEMFC prepared using the traditional powder catalyst spraying method by four times. High‐frequency resistance and limiting current tests indicate that the MnO2 NTM reduces ohmic resistance and improves mass transfer, thereby enhancing the HEMFC performance. Furthermore, the peak power density of the HEMFC is increased to 626 mW cm−2 by depositing additional active Co3O4 nanoparticles on the MnO2 NTM. These findings demonstrate that an interconnected and porous catalyst layer structure is beneficial for improving mass transfer properties, which in turn enhances HEMFC performance.

Comprehensive pathogen identification and antimicrobial resistance prediction from positive blood cultures using nanopore sequencing technology

BackgroundBlood cultures are essential for diagnosing bloodstream infections, but current phenotypic tests for antimicrobial resistance (AMR) provide limited information. Oxford Nanopore Technologies introduces nanopore sequencing with adaptive sampling, capable of real-time host genome depletion, yet its application directly from blood cultures remains unexplored. This study aimed to identify pathogens and predict AMR using nanopore sequencing.MethodsIn this cross-sectional genomic study, 458 positive blood cultures from bloodstream infection patients in central Taiwan were analyzed. Parallel experiments involved routine microbiologic tests and nanopore sequencing with a 15-h run. A bioinformatic pipeline was proposed to analyze the real-time sequencing reads. Subsequently, a comparative analysis was performed to evaluate the performance of species identification and AMR prediction.ResultsThe pipeline identified 76 species, with 88 Escherichia coli, 74 Klebsiella pneumoniae, 43 Staphylococcus aureus, and 9 Candida samples. Novel species were also discovered. Notably, precise species identification was achieved not only for monomicrobial infections but also for polymicrobial infections, which was detected in 23 samples and further confirmed by full-length 16S rRNA amplicon sequencing. Using a modified ResFinder database, AMR predictions showed a categorical agreement rate exceeding 90% (3799/4195) for monomicrobial infections, with minimal very major errors observed for K. pneumoniae (2/186, 1.1%) and S. aureus (1/90, 1.1%).ConclusionsNanopore sequencing with adaptive sampling can directly analyze positive blood cultures, facilitating pathogen detection, AMR prediction, and outbreak investigation. Integrating nanopore sequencing into clinical practices signifies a revolutionary advancement in managing bloodstream infections, offering an effective antimicrobial stewardship strategy, and improving patient outcomes.

Fetal Brain MRI Findings in Myotonic Dystrophy and Considerations for Prenatal Genetic Testing.

Congenital myotonic dystrophy type 1 (DM1) is a rare congenital neuromuscular disorder associated with high morbidity and potential early mortality requiring lifelong symptomatic management. Prenatal presentations of DM1 have been associated with nonspecific ultrasound findings such as clubbed foot, polyhydramnios, ventriculomegaly, and decreased fetal movement, but many cases of DM1 have no ultrasound anomalies. We sought to compare the clinical course and prenatal imaging findings in two cases of DM1 using retrospective chart review. This report demonstrates potential expansion of the prenatal phenotype of DM1 including fetal SVT and frontal bossing. Both cases shared unique prenatal imaging features of lateral ventricle dilation involving the anterior bodies and frontal horns on fetal MRI. Because congenital DM1 is most often maternally inherited, attention to maternal symptoms, physical examination, and family history can be helpful in recognizing cases. Molecular diagnosis of DM1 requires specialized testing of the 3' untranslated region of the DMPK gene, and DM1 will not be detected by current standard prenatal genetic testing with microarray, karyotype, or exome sequencing.

Clinic evaluation of cognitive impairment in post-COVID syndrome: Performance on legacy pen-and-paper and new digital cognitive tests

BackgroundCognitive impairment, colloquially termed “brain fog”, is one of the most prevalent manifestations of post-Covid syndrome and a major contributor to impaired daily function and reduced quality of life. However, despite the high numbers of affected individuals presenting to clinical services with cognitive impairment, little work has been undertaken to date on the suitability of current memory clinic tests for identifying the cognitive deficits in this new acquired cognitive disorder.The aim of this study was therefore to determine the performance of people with post-Covid syndrome presenting with cognitive impairment on the Addenbrooke's Cognitive Examination-III (ACE-III), a cognitive test used widely in memory clinics. A subset of individuals also underwent testing on a novel battery of short digital tests assessing attention, speed of information processing and executive function, representing the domains primarily implicated in post-Covid cognitive dysfunction. Methods102 individuals with post-Covid syndrome presenting with subjective cognitive complaints were recruited from a specialist cognitive long Covid clinic at University Hospitals Sussex NHS Trust. All participants completed self-report questionnaires on depression, anxiety, sleep and fatigue. Cognitive performance was assessed using the ACE-III, with 20 participants also being tested on the digital Long COVID Assessment Battery (LCCAB) (N = 20). ResultsThe overall sample had a mean ACE-III score of 91/100 (SD 6) with 15.7% (16/102) scoring at or below the cut-off score considered to represent objective cognitive impairment. Of the 20 individuals who also completed the LCCAB, 89.47% were impaired on at least one task, primarily in the domains of attention, executive function and processing speed. Cognitive performance was not associated with depression, anxiety, sleep quality or fatigue. ConclusionThe vast majority of individuals with post-Covid syndrome presenting with subjective cognitive complaints do not exhibit impaired performance on the ACE-III. This likely reflects the historical use of ACE-III and other pen and paper cognitive tests to detect cognitive impairment in diseases causing dementia, but they are ill-equipped to identify impairment in those cognitive domains affected in post-Covid syndrome. The LCCAB detected cognitive impairments in nearly 90% of participants, primarily affecting attention, executive function, and processing speed. These observations highlight the need for alternative cognitive tests for use in routine clinical practice to detect the impairments in new acquired cognitive disorders that are not adequately captured by legacy tests.

Design of a novel high-speed tensile method for testing the high strain rate tensile behavior of aluminum alloys.

The high-strain rate mechanical behavior of aluminum alloys is crucial for the stability of electromagnetic launch systems. However, current high-strain rate testing methods are not suitable for large-scale screening of materials needed in electromagnetic launch systems due to their low precision and high cost. In this paper, a novel method for high-strain rate tensile testing of aluminum alloys based on magnetic pulse driving was proposed. The method can generate a fast-rising edge and adjustable stress pulses to enable uniaxial tensile deformation, reaching a target strain rate quickly and keeping it constant. Based on the theory of stress wave transmission, a single-point method for measuring stress-strain relationship of the specimen combining digital image correlation (DIC) technology is proposed. Finite element simulations using the explicit finite element software LS-DYNA demonstrate a good agreement between the strains and strain rate with experimental values. Tensile tests were conducted on AA7075 in the strain rate range of 1000-3000s-1, the stress-strain relationship obtained from DIC agrees well with the results of traditional Hopkinson bar experiments.

Quantitative study of local defects by pulsed eddy current testing

Quantitative study of local defects by pulsed eddy current testing

Evaluation of Applied Destructive and Non-destructive Tests in the Technical Inspection Process of High-Frequency Electric Resistance Weld Pipes

Ensuring the absence of structural defects in metal pipes of the gas network requires production control and quality control tests. On the other hand, the main role of these pipes is the transmission of natural gas, therefore, the smallest leakage, along with damage to the environment and loss of natural gas, entails the dangers of explosion. In this article, all the quality tests performed on the raw materials and the metal pipe production process are mentioned, and the result of their optimization in terms of sampling, prototyping, and acceptance criteria in the quality control plan is given. In addition to destructive tests, three important non-destructive methods including industrial radiography, ultrasonic test, and eddy current test have been specially investigated. The statistical results of detectable defects for three specific sizes of pipes including 4, 6, and 8 inches have been collected. The final result of this essay is the optimization of high-frequency electric resistance welding pipe production.

A weak bias-magnetized dynamic permeability testing method for detecting and distinguishing inner and outer diameter defects in gas pipelines

Detecting and distinguishing inner diameter (ID) and outer diameter (OD) defects in gas pipelines is crucial for their safe operation. However, current methods such as eddy current testing (ECT) and saturated magnetic flux leakage (MFL) are unable to meet the detection requirements due to the small diameter and low pressure of gas pipelines. Therefore, this paper presents a weak bias-magnetized dynamic permeability testing (DPT) method, using a differential probe with AC coils and magnetic cores to sense varying physical quantities in the ID surface caused by defects. For ID defects, the varying physical quantities include both dynamic permeability and conductivity, whereas for OD defects, it is solely dynamic permeability. This paper thoroughly analyzes the detection principle and completes the coil impedance model. A simulation model for small AC electromagnetic fields with DC bias is established, and an impedance detection instrument is developed for further experimental investigation. The results show that the weak bias-magnetized DPT can detect both ID and OD defects and distinguish them based on clear differences in the signal waveform. Compared to ECT and MFL, the DPT method has the highest ratio of OD to ID defect signal magnitude, indicating minimal signal attenuation as the buried depth of defects increases. Moreover, a pipeline internal inspection device based on DPT has been developed, demonstrating its capability to detect OD defects with a small drag force.

Investigation on size effects of ultra-high-performance concrete: experimental and numerical study

ABSTRACT Test specimens with smaller sizes seem to be preferable because using standard specimen sizes for ultra-high-performance concrete (UHPC) can lead to issues owing to the current testing equipment’s capacity limitations. Therefore, the size effect investigation of the UHPC specimens is necessary. In this paper, the UHPC mix was used to explore the size effect on the compression and flexural response of the cylinder and beam specimens, respectively. The UHPC mix was cast into various-sized cylinders and beams with diameters ranging from 50 to 150 mm and heights/widths from 50 to 150 mm, respectively. A nonlinear 3D finite element (FE) model has been created in ABAQUS software for all UHPC specimens. Additionally, validation was done using the experimental findings of this study. The findings clearly revealed that the compressive and flexural strength decreases with increasing the size of the specimen. The larger specimens revealed a slight reduction in compressive strength between 1.4% and 9.5%, while a considerable reduction was recorded in flexural strength, where the larger specimens showed reduction ratios between 19.1% and 35.6%. Furthermore, the experimental and FE findings were in satisfactory agreement and exhibited virtually identical overall trends.

Electrochemical interaction behaviors between adjacent zinc-rich coating defects on steel structures under immersion and wet–dry environments

This study investigates the corrosion mechanism of carbon steel beneath zinc-rich coating (ZRC) defects to understand the mutual interference of carbon steel in atmospheric environments. First, electrochemical impedance spectroscopy (EIS) was conducted to determine the self-corrosion behavior of carbon steel under ZRC defects. Subsequently, a macrocell current tests were conducted under immersion and wet–dry environments to evaluate the electrochemical interaction effects at the location of coating defects. The results indicate that the electrochemical interactions between the ZRC defects are influenced by the sacrificial anode effect of Zn. Further, the interaction mechanisms between the steel substrates beneath the organic and inorganic ZRC defects were analyzed. The findings provide deeper insight into the behavior of steel structures in atmospheric environments, offering potential improvements in the design of protective coatings for infrastructure longevity.

Conductivity Estimation of Metallic Tubes Using Ferrite Core Horizontal Probe with Eddy Current Method

Conductivity evaluation is crucial for monitoring the condition of metallic tubes during inspections and for assessing their service life. Eddy current testing (ECT) is a precise, non-contact method used for this purpose. Industries such as aerospace, power generation, and petrochemicals rely on precise condition monitoring, which requires a deep understanding of the relationship between conductivity variations and probe impedance of metallic tubes. However, experimental analysis of conductivity changes using coil impedance has limitations in terms of cost and complexity. Encircling coil methods provide overall information about the average conductivity of specimens but have limited ability to capture local variations such as hot spots. To address these issues, we propose using a finite element method (FEM) based approach to predict a ferrite core horizontal probe signal near non-ferromagnetic tubes. The probe data can be used to estimate conductivity through regression methods, and the impact of lift-off on ECT results is also investigated.

Summary of the National Institute of Allergy and Infectious Diseases workshop on Alternative Therapies to Penicillin for the Treatment of Syphilis.

The dramatic increase in syphilis cases in the United States in recent years is a serious public health concern. Periodic shortages of benzathine penicillin (BPG), the mainstay of syphilis treatment, create challenges for management of syphilis in the U.S. and worldwide. The National Institute of Allergy and Infectious Diseases (NIAID) convened working groups of experts to assess the landscape of syphilis treatments for uncomplicated adult syphilis, syphilis in pregnant persons, congenital syphilis, and neurosyphilis. The working groups came together at a workshop entitled "Alternative Therapies to Penicillin for the Treatment of Syphilis" on February 13-14, 2024, to share their findings regarding promising alternative treatments, research gaps, and challenges. Discussions focused on utilizing existing antibiotics, with a preference for those with favorable safety profiles and demonstrated success against syphilis or other infectious diseases. Clinical research on alternative treatments is complicated by the high effectiveness of penicillin and by differences in clinical, physiological, cultural, and socioeconomic considerations across different patient populations and geographic settings. In addition, current diagnostic tests and tests-of-cure create challenges for clinical trial design. Various potential trial designs were discussed, focusing on subjects with different types and stages of disease. This summary of the workshop is presented to inform plans for future research, including clinical trials on alternatives to penicillin for the treatment of syphilis.

Rapid enzymatic assay for antiretroviral drug monitoring using CRISPR-Cas12a enabled readout.

Maintaining efficacy of human immunodeficiency virus (HIV) medications is challenging among children because of dosing difficulties, the limited number of approved drugs, and low rates of medication adherence. Drug level feedback (DLF) can support dose optimization and timely interventions to prevent treatment failure, but current tests are heavily instrumented and centralized. We developed the REverse-transcriptase ACTivity-crispR (REACTR) assay for rapid measurement of HIV drugs based on the extent of DNA synthesis by HIV reverse transcriptase. CRISPR-Cas enzymes bind to synthesized DNA, triggering collateral cleavage of quenched reporters and generating fluorescence. We measured azidothymidine triphosphate (AZT-TP), a key drug in pediatric HIV treatment, and investigated the impact of assay time and DNA template length on REACTR's sensitivity. REACTR selectively measured clinically relevant AZT-TP concentrations in the presence of genomic DNA and peripheral blood mononuclear cell lysate. REACTR has the potential to enable rapid point-of-care HIV DLF to improve pediatric HIV care.

Oropharyngeal gonorrhoea among heterosexual men and women at a sexual health centre in Rotterdam, the Netherlands, 2023: reservoir for transmission?

BackgroundSexual health centres (SHCs) in the Netherlands report a surge in gonorrhoea, especially among young women (notably oropharyngeal) and men who have sex with women (MSW) since the second half...

Development of a clinical metagenomics workflow for the diagnosis of wound infections

BackgroundWound infections are a common complication of injuries negatively impacting the patient’s recovery, causing tissue damage, delaying wound healing, and possibly leading to the spread of the infection beyond the wound site. The current gold-standard diagnostic methods based on microbiological testing are not optimal for use in austere medical treatment facilities due to the need for large equipment and the turnaround time. Clinical metagenomics (CMg) has the potential to provide an alternative to current diagnostic tests enabling rapid, untargeted identification of the causative pathogen and the provision of additional clinically relevant information using equipment with a reduced logistical and operative burden.MethodsThis study presents the development and demonstration of a CMg workflow for wound swab samples. This workflow was applied to samples prospectively collected from patients with a suspected wound infection and the results were compared to routine microbiology and real-time quantitative polymerase chain reaction (qPCR).ResultsWound swab samples were prepared for nanopore-based DNA sequencing in approximately 4 h and achieved sensitivity and specificity values of 83.82% and 66.64% respectively, when compared to routine microbiology testing and species-specific qPCR. CMg also enabled the provision of additional information including the identification of fungal species, anaerobic bacteria, antimicrobial resistance (AMR) genes and microbial species diversity.ConclusionsThis study demonstrates that CMg has the potential to provide an alternative diagnostic method for wound infections suitable for use in austere medical treatment facilities. Future optimisation should focus on increased method automation and an improved understanding of the interpretation of CMg outputs, including robust reporting thresholds to confirm the presence of pathogen species and AMR gene identifications.

Rapid and non-invasive analysis of paracetamol overdose using paper arrow-mass spectrometry: a prospective observational study

BackgroundParacetamol is the most consumed medicine globally. Its accessibility contributes to common overdose. Paracetamol overdose is responsible for > 50% of acute liver failure cases, making it the second most common reason for a liver transplant. Rapid quantitation of paracetamol is crucial to guide treatment of paracetamol overdose. Current tests require invasive sampling and relatively long turnaround times. Paper arrow-mass spectrometry (PA-MS) combines sample collection, extraction, separation, enrichment and ionisation onto a single paper strip, achieving rapid, accurate, cost-effective and eco-friendly analysis direct from raw human saliva.MethodsTo validate PA-MS against an established test, 17 healthy adults were recruited. Samples were collected before and at 15, 30, 60, 120 and 240 min after ingesting 1 g of paracetamol. Plasma measured with an established clinical test served as the reference standard to validate PA-MS with three biofluids—plasma, resting saliva (RS) and stimulated saliva (SS). Participants’ views of blood, RS and SS sampling procedures were assessed qualitatively. Cross-validation was assessed using Lin’s concordance correlation coefficients (CCC), Bland–Altman difference plots, and ratios of PA-MS to the reference standard test.ResultsPA-MS using stimulated saliva offers a reliable alternative to intravenous blood sampling. The CCC is 0.93, the mean difference with the reference test is − 0.14 mg/L, and the ratios compared to the reference test are 0.84–1.27 from correlated samples collected at 5 intervals over 4 h for each participant.ConclusionsParacetamol detection from SS with PA-MS provides a reliable result that can aid timely treatment decisions. Differences between paracetamol concentration in resting and stimulated saliva were also identified for the first time, highlighting the importance of standardising saliva collection methods in general. This study marks a major milestone towards rapid and convenient saliva analysis.

SIMTAM: Generation Diversity Test Programs for FPGA Simulation Tools Testing Via Timing Area Mutation

Field-Programmable Gate Array (FPGA) timing simulation is essential in electronic circuit design, allowing for the verification of timing characteristics like delays and clock frequencies. However, bugs in timing simulation tools can lead to inaccurate results, potentially causing designers to miss critical issues in chip performance. Traditional testing methods often fall short in thoroughly assessing these tools, as current FPGA testing primarily focuses on synthesis and behavioral simulation, neglecting timing aspects. To address this issue, we propose SIMTAM for testing timing simulation tools. Specifically, SIMTAM consists of three components: equivalent delay region construction, diversity program segment generation, and differential testing. Given a seed circuit design file written by hardware description language such as Verilog, the delay region construction component randomly identifies delay structures for inertial delay in the design file to construct equivalent delay sleep regions. In the sleep region, the simulator skips the signal pulse whose width is less than the specified delay, thus ensuring the equivalence of the variations. The diversity program segment generation component combines Verilog expressions using generation operators and inject them into the sleep region to generate diverse design files. The differential testing component compares the seed and variant design files to find compilation inconsistency issues. In five months, SIMTAM reported 16 bugs to developers in two popular timing simulation tools Iverilog and Vivado; ten of which are confirmed.

Consensus Statement: Recommendations on Actionable Biomarker Testing for Thyroid Cancer Management.

Thyroid cancer management is rapidly changing. The identification of actionable biomarkers through both germline and somatic testing are now an integral part of directing patient management. However, deficiencies and disparities within existing thyroid cancer biomarker test approaches are resulting in inconsistent application for patient care. An expert panel was convened to create consensus biomarker testing algorithms and recommendations on actionable biomarker testing for patients diagnosed with medullary thyroid cancer, non-anaplastic follicular cell-derived thyroid cancer, or anaplastic follicular cell-derived thyroid cancer who may benefit from targeted therapies. A review of international guidelines was performed to determine the current state, and a literature review was carried out to further evaluate the evidence supporting the use of actionable biomarkers in patients diagnosed with thyroid cancer. Thyroid biomarker-related gaps impacting patient care were also discussed, with an emphasis on the importance of a multidisciplinary team approach for optimal patient care. The recommendations are presented with the aim to help physicians navigate the current thyroid cancer biomarker testing landscape with its many challenges, balancing aspirational care with what is practical and feasible in terms of economic realities and jurisdictional constraints. By remaining therapy-agnostic, these algorithms and recommendations are broadly applicable.