Detection Principle Research Articles

Evaluation of three rapid assays for detecting Mycoplasma pneumoniae in nasopharyngeal specimens

During the 2023 autumn–winter period in China, Mycoplasma pneumoniae (MP) infections have increased. To address this, rapid and accurate MP DNA detection methods are crucial. Three nucleic acid detection assays (Ustar, Coyote Flash10, Coyote Flash 20) that are widely used in China are currently being evaluated for their effectiveness in detecting MP DNA in nasopharyngeal specimens. Reference standard materials for MP and a total of 35 NPS collected from Peking Union Medical College Hospital were tested using the Ustar, Coyote Flash10 and Coyote Flash 20 assays to assess analytical sensitivity, analytical specificity, diagnostic performance and workflow. The assays showed differing limits of detection (LOD) based on the absolute quantification of reference standards, with LODs of 500 copies/mL for the Ustar assays and 200 copies/mL for both Coyote Flash10 and Coyote Flash 20 assays. Additionally, all three assays displayed excellently analytical specificity in detecting MP DNA.The clinical correlation analysis demonstrated that the Ustar assay exhibited a sensitivity of 90.00%, specificity of 100%, positive predictive value (PPV) of 100%, and negative predictive value (NPV) of 62.50%. In contrast, both the Coyote Flash10 and Coyote Flash 20 assays displayed perfect diagnostic accuracy with 100% sensitivities, specificities, PPVs, and NPVs. Despite variations in detection principles, sample volume, and pre-preparation among the three assays, they all had a turnaround time of less than 30 min with low-throughput processing. Overall, all three rapid nucleic acid detection assays displayed excellent clinical performance in detecting MP DNA, offering a solid foundation for the quick clinical diagnosis of MP infection.

Machine-learning-enhanced automatic spectral characterization of x-ray pulses from a free-electron laser

A reliable characterization of x-ray pulses is critical to optimally exploit advanced photon sources, such as free-electron lasers. In this paper, we present a method based on machine learning, the virtual spectrometer, that improves the resolution of non-invasive spectral diagnostics at the European XFEL by up to 40%, and significantly increases its signal-to-noise ratio. This improves the reliability of quasi-real-time monitoring, which is critical to steer the experiment, as well as the interpretation of experimental outcomes. Furthermore, the virtual spectrometer streamlines and automates the calibration of the spectral diagnostic device, which is otherwise a complex and time-consuming task, by virtue of its underlying detection principles. Additionally, the provision of robust quality metrics and uncertainties enable a transparent and reliable validation of the tool during its operation. A complete characterization of the virtual spectrometer under a diverse set of experimental and simulated conditions is provided in the manuscript, detailing advantages and limits, as well as its robustness with respect to the different test cases.

Ultrafast mid-infrared interferometric photocurrents in graphene-based two-terminal devices

We demonstrate that graphene-based two-terminal devices allow autocorrelating femtosecond mid-infrared pulses with a pulse duration of about 100 fs in the wavelength regime of 5.5–14 μm. The results suggest that the underlying ultrafast detection principle relies on an electric field dominated autocorrelation in combination with the optoelectronic dynamics at the metal–graphene interfaces. The demonstrated scheme excels because of the ease in nanofabrication of two-terminal graphene-based optoelectronic devices and their robustness.

Dark matter-electron scattering search using cryogenic light detectors

The cryogenic scintillating calorimeter technology devoted to rare event searches is reaching the sensitivity level required for the hunt of dark matter-electron scatterings. Dark matter-electron interactions in scintillating targets are expected to stimulate the emission of single photons, each of energy equal to the target electronic band gap. The electronic band gap in scintillators like NaI/GaAs is of O(eV). The search for this signal can be done by an array of cryogenic light detectors with eV/sub−eV energy resolution. In this work, we describe the detection principle, the detector response, and the envisioned detector design to search for dark matter interacting with electrons via the measurement of the scintillation light at millikelvin. First sensitivity projections are provided, which show the potential of this research. Published by the American Physical Society 2024

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.

Direct colorimetric detection of triacetone triperoxide explosive by hydroxylamine-mediated fenton chemistry catalyzed by goethite nanoparticles

Due to the absence of nitro groups or aromatic structures in its structure, spectrophotometric methods that can directly determine triacetone triperoxide (TATP) are absent. In the proposed study, a molecular spectroscopic sensor was developed based on the decomposition of TATP by hydrolysis without the addition of external acid, allowing the direct determination of TATP. The detection principle of the developed sensor is based on the decomposition of TATP by the hydrochloric acid formed as a result of the reaction of TATP with hydroxylamine hydrochloride, taking advantage of the solubility of TATP in acetone, and the hydrogen peroxide formed as a degradation product to form hydroxyl radicals catalyzed by goethite nanoparticles. The formed hydroxyl radicals, thanks to their strong oxidation properties, oxidized N,N-dimethyl-p-phenylenediamine (DMPD) to the pink-colored DMPD•+ radical cation, and the direct determination of TATP was performed by measuring the absorbance of the colored product formed. Thus, a chemo-cybernetic sequence of reactions is proposed for intact TATP assay in a circular self-sustained system, where the reactants at a given step of reactions are supplied by the products of a previous step. By applying the developed method to TATP samples prepared in acetone, absorbances due to DMPD•+ were read at 554 nm to evaluate the results. A calibration curve was created between absorbance versus TATP concentration within a final range of 10 – 33 mg L-1. The limit of detection (LOD) and limit of quantification (LOQ) of the developed TATP method were 3.3 mg L-1 and 10.8 mg L-1, respectively. Five replicate measurements were performed to determine the intra-assay and inter-assay precision of the spectrophotometric determination of TATP, and the relative standard deviations (RSD %) for TATP were found as 2.70 % and 3.76 %, respectively. Interference analysis was carried out to see the effects of ions commonly present in soil/groundwater, and of the substances used as camouflage materials due to their color and appearance similarity to TATP. The selectivity of the method toward TATP was investigated by examining the analyte recovery from explosive mixtures. The developed method was validated against a reference GC–MS method using TATP-contaminated soil samples, and the results were compared statistically.

GWO-elman based composite detection of transformer oil flow temperature

This paper addresses the issue of nonlinear coupling error caused by cross-sensitivity of strain and temperature in the composite detection of flow rate and temperature in transformer oil using a Fiber Bragg Grating (FBG) sensor. This paper focuses on the FBG sensor as the research object, elucidating the underlying principles of composite detection. Subsequently, a composite detection experimental platform is established for the purpose of analyzing the coupling error of flow rate and temperature. Ultimately, a nonlinear decoupling algorithm based on the Grey Wolf Optimizer (GWO) is proposed to enhance the nonlinear decoupling algorithm of the Elman neural network (simple recurrent neural network, Elman). The findings demonstrate that within the flow rate range of 0–5 m/s and the temperature range of 30 °C–150 °C, the maximum error is reduced by 72.0 % and 81.3 %, and the average error is reduced by 74.4 % and 79.4 %. This significantly enhances the precision and reliability of the sensor’s detection capabilities.

Eddy current quantitative evaluation of high-speed railway contact wire cracks based on neural network

PurposeThe purpose of this study is to study the quantitative evaluation method of contact wire cracks by analyzing the changing law of eddy current signal characteristics under different cracks of contact wire of high-speed railway so as to provide a new way of thinking and method for the detection of contact wire injuries of high-speed railway.Design/methodology/approachBased on the principle of eddy current detection and the specification parameters of high-speed railway contact wires in China, a finite element model for eddy current testing of contact wires was established to explore the variation patterns of crack signal characteristics in numerical simulation. A crack detection system based on eddy current detection was built, and eddy current detection voltage data was obtained for cracks of different depths and widths. By analyzing the variation law of eddy current signals, characteristic parameters were obtained and a quantitative evaluation model for crack width and depth was established based on the back propagation (BP) neural network.FindingsNumerical simulation and experimental detection of eddy current signal change rule is basically consistent, based on the law of the selected characteristics of the parameters in the BP neural network crack quantitative evaluation model also has a certain degree of effectiveness and reliability. BP neural network training results show that the classification accuracy for different widths and depths of the classification is 100 and 85.71%, respectively, and can be effectively realized on the high-speed railway contact line cracks of the quantitative evaluation classification.Originality/valueThis study establishes a new type of high-speed railway contact wire crack detection and identification method, which provides a new technical means for high-speed railway contact wire injury detection. The study of eddy current characteristic law and quantitative evaluation model for different cracks in contact line has important academic value and practical significance, and it has certain guiding significance for the detection technology of contact line in high-speed railway.

Simultaneous and Rapid Detection of Glucose and Insulin: Coupling Enzymatic and Aptamer-Based Assays.

Diabetes management demands precise monitoring of key biomarkers, particularly insulin (I) and glucose (G). Herein, we present a bioelectronic chip device that enables the simultaneous detection of I and G in biofluids within 2 min. This dual biosensor chip integrates aptamer-based insulin sensing with enzymatic glucose detection on a single platform, employing a four-electrode sensor chip. The insulin voltammetric sensor employs a G-quadraplex methylene-blue-modified aptamer, while the amperometric biocatalytic glucose sensor utilizes a second-generation mediator-based approach. Simultaneous reagent-less sensing of I and G has been achieved by addressing key challenges. These include combining different surface chemistries, assay formats, and detection principles at closely spaced working electrodes and the substantially different concentration levels of the I and G targets. An attractive analytical performance, with no apparent crosstalk, is demonstrated for the simultaneous detection of millimolar G concentrations and picomolar I concentrations in single microliter serum or saliva sample droplets. This dual biosensor offers rapid, cost-effective, and reliable monitoring, addressing the unmet need for integrated multiplexed diabetes biomarker detection in decentralized settings. Such integration of enzymatic and aptamer-based bioassays could greatly expand the scope of decentralized testing in healthcare beyond diabetes care.

Establishment and Application of a New Radiation Biodosimetric Method Based on the Quantitative RPA-SHERLOCK Amplification Technology.

Biodosimetry is a key diagnostic tool for radiation exposure, risk assessment and treatment planning of acute radiation sickness. To effectively respond to a large-scale radiological incident, there is a need for the development of biodosimetric methods with fast, portable, and convenient operating advantages. We employed the recombinase polymerase amplification specific high-sensitivity enzymatic reporter unlocking (RPA-SHERLOCK) technology to establish a method for fast radiation dose assessment by measuring the expression level of radiation-inducible genes. Moreover, we proposed for the first time the principle of quantitative detection of curve slopes based on this method. Using this new method, changes in mRNA expression were confirmed in a number of radiation-sensitive genes (XPC, CDKN1A, and ATM) in human lymphocytes after irradiation. The standard curve of the dose-effect relationship was established, which can be used to quickly determine the exposed dose of the irradiated samples. Compared with traditional detection methods such as RT-qPCR, this method was found to be more convenient, fast and easy to operate. With the same amount of template input as RT-qPCR, the detection time of this method can be shortened to less than 20 min. The detection instrument required by this method is also more portable than a qPCR system.

UTHP spectrometer: an ultra-thin and high-performance imaging spectrometer for ocean color remote sensing in broadband

The principle of ocean color detection involves using satellite sensors to capture variations in received signals, which are subsequently analyzed to infer the concentrations of various components responsible for ocean color changes. In recent years, significant research advancements have been achieved, centered on the development of ocean color detectors and the analysis of the resulting data. We have developed an innovative ultra-thin high-performance (UTHP) scanning imaging spectrometer for ocean color remote sensing across the near ultraviolet-visible-near infrared (NUV-VIS-NIR) spectrum. This spectrometer overcomes the bulkiness of conventional equipment by integrating a waveguide platform that replaces traditional optical elements with a single flat glass panel, featuring curved surfaces and high-reflectivity coatings to perform essential optical functions. We believe this to be a novel design that greatly reduces the size and weight of the device, making it highly suitable for deployment on various platforms, including aircraft and satellites. The optical system underwent extensive testing, including simulations using Zemax software and physical prototyping, achieving a spectral resolution of less than 3 nm across the 400-1000 nm waveband while maintaining low distortion. The UTHP spectrometer’s compactness, lightweight design, and exceptional performance mark a significant advancement in imaging spectrometry, with the potential to transform remote sensing by providing more efficient, accessible methods for studying expansive oceanic regions.

ICRF resonance cones in the low-density scrape-off-layer of ASDEX Upgrade

Abstract The ICRF slow wave is a potential carrier for parallel RF electric fields known to cause unwanted plasma-wall interactions in magnetic confinement fusion experiments.
In nowadays machines the slow wave is usually confined to the far scrape-off layer or the limiter shadow, but conditions in future experiments and reactors may allow the slow wave to be propagative in a larger region.

Simulations with RAPLICASOL for various geometries show that the ICRF slow waves appear as the so-called resonance cones characterized by large localized electric fields.
The resonance cones emerge from the points along the plasma-antenna interface where (in the cold plasma approximation) the radio frequency electric field diverges.
We demonstrate that in the parameter range of interest, the propagation of the resonance cones in a plasma with a density gradient is defined by a simple geometric model, using the local plasma density and the frequency as input parameters.
In the context of experiments at ASDEX Upgrade, simulations illustrate that the resonance cones can emerge from a single tile of the ICRF antenna limiter.
Experiments at the Ion-cyclotron System Hardware Test ARrangement (ISHTAR) were conducted to test the detection principle in a simple environment.
In agreement with simulations and with predicted characteristics which depend on operation parameters, the resonance cones are excited by an RF antenna and propagate through the relatively homogeneous plasma in ISHTAR. 
The cones are detected at a distance from the antenna using two probes scanning through the plasma.
In ASDEX Upgrade, a single tile of an antenna limiter was modified to launch RF power into a specially tailored low-density scrape-off layer.
Probes at the midplane manipulator were then used to detect the wave electric fields at a distance from the RF source.
The detected RF signals show that the signal maxima are located close to the lower hybrid resonance density and are highest when the source and the probes are connected along magnetic field lines.
These observations agrees with the model for resonance cones from the simulations.

An electrochemical biosensor for the detection of tuberculosis specific DNA with CRISPR-Cas12a and redox-probe modified oligonucleotide

BackgroundThe development of a robust and accurate point-of-care platform for the detection of tuberculosis (TB) biomarkers is important for disease control. In the current study, the detection principle relies on the shredding of PES-modified non-specific ssDNA (Poly T) in the presence of target DNA IS6110, a reliable biomarker for TB diagnosis by the CRISPR-Cas12a mechanism. Cas protein has great potential in the detection of nucleic acids. ResultsHerein, we developed a biosensing platform by utilizing the trans cleavage activity of CRISPR-Cas12a into an electrochemical biosensor. Square wave voltammetry technique is used for the analysis of the fabricated biosensing platform. In the presence of target DNA, the trans cleavage activity is observed by a nonspecific ssDNA substrate, PolyT chain. Various concentration of target DNA is tested on the constructed biosensor, the fabricated biosensor successfully detected TB target DNA by trans cleavage of PES-modified poly T. This novel biosensor was able to detect the target DNA, IS6110 with the limit of detection of 14.5 nM within 60 min by trans-cleavage activity of CRISPR-Cas12a and the results revealed the potential of Cas12a-based biosensors as a diagnostic platform. SignificanceThis is the first study reporting the CRISPR-Cas12a-based electrochemical sensor for TB. The developed CRISPR-Cas12a endonuclease-based electrochemical biosensor provides a potentially powerful platform for the accurate detection of Mycobacterium tuberculosis.

Unmanned unexploded ordnance detection system based on magnetic method

Abstract Magnetic method is one of the main methods of UXO detection. This paper uses cesium optical pump magnetic detection module combined with UAV to build an unmanned UXO detection system, and introduces the detection principle and composition of the system. At the same time, the system is used to detect four kinds of UXO targets. The test results show that the system can detect ferromagnetic UXO targets, and can locate the position of UXO targets through magnetic anomaly images. Finally, the limit detection range of four kinds of targets is tested, and the limit detection range of 155 projectiles can reach 4.5m, which meets the actual detection requirements

Miniaturized optical system of a laser seeker based on a dynamic and static performance co-design

The laser semi-active seeker, crucial for miniaturizing guided munitions, offers high precision, anti-jamming, and rapid response. Current research focuses on system response, spot parameters, and angular velocity accuracy. With small-caliber munitions on the rise, further miniaturization and weight reduction are essential. This paper proposes a design for an optical system that balances dynamic imaging quality and miniaturized static structure. Using quadrant detector principles, factors affecting detection performance are analyzed to determine the optimal spot size and imaging range. Based on imaging requirements and the optical properties of a dual-reflector structure, we determine the design parameters of the system to achieve a combination of dynamic and static performance. Evaluations using ZEMAX and MATLAB confirm that the system achieves ±4∘ linear and ±8∘ full fields of view, 0.12% distortion, 4.52 mrad angular accuracy, a 15.72 mm axial length, and has the possibility of actual production. The system is compact, with excellent spot roundness, stability, and uniform energy distribution, providing a reference for future guided weapon research.

Analysis of the Principle for Gravitational Wave Detection Based on Pulsar Timing Arrays

As a matter of fact, the hunt for gravitational waves have been under the spotlight since LIGO researchers took home the Nobel Prize. In reality, different from the laser interferometers used by LIGO, pulsar timing arrays are also feasible ways to detect gravitational waves. With this in mind, this article will mainly focus on how pulsar timing arrays could detect gravitational waves as well as its achievements so far. To be specific, pulsar timing arrays consisted of rotating pulsars in space, and their regular burst of radio waves serve as stopwatches. When gravitational waves pass by, the frequency at which human beings’ receiving radio waves will change at the same time. Pulsar timing array projects around the world have been busy recording pulsars up to now, but more discoveries will come out soon. They also utilized their data to verify previous calculations such as the Helling-Downs curve. According to the analysis, the current limitations and prospects are demonstrated.

Analysis of the Principle of Gravitational Wave Detection and State- of-art Results

Over one hundred years after Einstein’s first theoretical prediction of gravitational waves, the recent observations of gravitational waves by interferometric detectors have risen excitement in the science community with the light from a new era of directly observing perturbations in spacetime itself. With the large quantity of new research in the gravitational wave detection area, this study provides a brief summary of the current achievements of the field. This paper first gives a short introduction of the field, then offers a summarize of the theories and principles of gravitational wave detection. Afterwards, it demonstrates modern detectors using the advanced LIGO detectors as an example, and presents its groundbreaking results, signal GW150914 and GW151226. Finally, the limitations and prospects of current observations are proposed. By summarizing fundamental concepts and major achievements in the field of gravitational wave detection, it is hoped to provide future students and researchers with a basic idea of the field and thus promote new ideas and advancements in the rising era of gravitational astronomy.

Research on the Detection Principle of Coal Ash by X-Ray Transmission Based on FLUKA

This study addresses the timely and accurate measurement of coal ash content by proposing a detection model based on nuclear science technology, which is validated using FLUKA 4-4.0 simulation software. The background provided highlights the fact that coal ash content is a critical sales indicator, and its precise measurement is essential for adjusting production parameters in coal preparation plants. In terms of methodology, this study employs the widely used FLUKA4-4.0 software in the field of nuclear physics to simulate X-ray transmission through coal, investigating the impact of changes in coal type on the accuracy of ash measurements. The results indicate that, when the proportions of high-atomic-number elements in coal remain constant, the ash measurement results are accurate and reliable. However, significant fluctuations occur when these proportions change. The conclusion emphasizes the fact that variations in coal type are the primary cause of inaccuracies in ash measurement, particularly when the ratios of high-atomic-number elements are altered. This research provides a new perspective on the online measurement of coal ash content and offers theoretical support for improving measurement accuracy.

Ultrasensitive on-site colorimetric detection of Campylobacter in oyster with a portable biosensing platform based on hydroxamate/Fe3+–violurate chromogenic reaction and smartphone

The contamination of Campylobacter in shellfish poses a health risk for its pathogenicity associated with campylobacteriosis. However, an efficient method to detect this risk is unavailable. Herein, we introduce a portable colorimetric biosensing platform that comprises three modules: an enrichment module 1, a binding and transduction module 2, and a smartphone-based module 3. Module 1 is an aptamer-modified 96-well plate for the specific capture of Campylobacter in a simple and high-throughput manner. Module 2 features a bifunctional biopolymer of L-glutamic acid γ-hydroxamate–alginate–Fe3+ coordinating fusarinine C, which can bind the captured Campylobacter cells and transduce them into amplified color signals upon reaction with Fe3+–violurate complexes. Module 1 achieves a capture efficiency of 97.24 %, and the subsequent addition of module 2 renders colorimetric indication of Campylobacter ranging from 101 to 106 CFU/mL, achieving an actual limit of detection of 8 CFU/mL validated by Campylobacter single-cells. Moreover, the generated colors can be recognized and converted into cell densities by module 3 with ultrasensitivity. Notably, this biosensor–smartphone platform accomplishe reliable high-throughput colorimetric detection of Campylobacter in real samples with an accuracy of 80 %. This work showcases a proof of principle for efficient on-site detection of Campylobacter contamination regarding shellfish farming.

Impedance Spectroscopy for Bacterial Cell Monitoring, Analysis, and Antibiotic Susceptibility Testing.

Conventional approaches for bacterial cell analysis are hindered by lengthy processing times and tedious protocols that rely on gene amplification and cell culture. Impedance spectroscopy has emerged as a promising tool for efficient real-time bacterial monitoring, owing to its simple, label-free nature and cost-effectiveness. However, its limited practical applications in real-world scenarios pose a significant challenge. In this review, we provide a comprehensive study of impedance spectroscopy and its practical utilization in bacterial system measurements. We begin by outlining the fundamentals of impedance theory and modeling, specific to bacterial systems. We then offer insights into various strategies for bacterial cell detection and discuss the role of impedance spectroscopy in antimicrobial susceptibility testing (AST) and single-cell analysis. Additionally, we explore key aspects of impedance system design, including the influence of electrodes, media, and cell enrichment techniques on the sensitivity, specificity, detection speed, concentration accuracy, and cost-effectiveness of current impedance biosensors. By combining different biosensor design parameters, impedance theory, and detection principles, we propose that impedance applications can be expanded to point-of-care diagnostics, enhancing their practical utility. This Perspective focuses exclusively on ideally polarizable (fully capacitive) electrodes, excluding any consideration of charge transfer resulting from Faradaic reactions.