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Novel spectrofluorimetric approach for determination of ledipasvir through UV-irradiation: application to biological fluids, pharmacokinetic study and content uniformity test
摘要： A highly sensitive and specific fluorescence dependent approach was created for quantitation of a recently approved anti-HCV drug (ledipasvir). This approach relies on the innovative enhancement in fluorescence intensity of ledipasvir upon exposing the cited drug to direct UV irradiation as a photo-physical fluorescence enhancer. The fluorescence of the resultant solution was measured at an emission peak of 375 nm (321 nm excitation). The photoluminescence properties of the resultant product were carefully examined and the quantitative rectilinear concentration plot for the method was 5.0–150.0 ng mL?1 with a detection limit of 0.9 ng mL?1 and a quantitation limit of 2.7 ng mL?1. The excellent analytical features of the proposed method allow to the specific and sensitive estimation of ledipasvir either in plasma samples or in tablet dosage form without any interference from pharmaceutical excipients or other co-formulated anti-HCV drugs (sofosbuvir). The developed analytical and bio-analytical procedures were created and validated according to ICH guidelines and FDA guidelines, respectively. Since the main elimination route for ledipasvir is via faecal excretion, the studied drug was determined for the first time in faecal samples by the method with adequate recovery. Moreover, the pharmacokinetic parameters (Cmax, tmax, t1/2, AUC0–t, and AUC0–N) for ledipasvir were determined by the proposed method. Additionally, the proposed method was successfully applied for supervising the content uniformity for ledipasvir in pharmaceutical tablets.
关键词： UV-irradiation,pharmacokinetic study,spectrofluorimetric,biological fluids,content uniformity test,ledipasvir
更新于2025-09-16 10:30:52
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Incorporating Statistical Test and Machine Intelligence Into Strain Typing of Staphylococcus haemolyticus Based on Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry
摘要： Staphylococcus haemolyticus is one of the most significant coagulase-negative staphylococci, and it often causes severe infections. Rapid strain typing of pathogenic S. haemolyticus is indispensable in modern public health infectious disease control, infections to prevent further infectious facilitating the identification of the origin of outbreak. Rapid identification enables the effective control of pathogenic infections, which is tremendously beneficial to critically ill patients. However, the existing strain typing methods, such as multi-locus sequencing, are of relatively high cost and comparatively time-consuming. A practical method for the rapid strain typing of pathogens, suitable for routine use in clinics and hospitals, is still not available. Matrix-assisted laser desorption ionization-time of flight mass spectrometry combined with machine learning approaches is a promising method to carry out rapid strain typing. In this study, we developed a statistical test-based method to determine the reference spectrum when dealing with alignment of mass spectra datasets, and constructed machine learning-based classifiers for categorizing different strains of S. haemolyticus. The area under the receiver operating characteristic curve and accuracy of multi-class predictions were 0.848 and 0.866, respectively. Additionally, we employed a variety of statistical tests and feature-selection strategies to identify the discriminative peaks that can substantially contribute to strain typing. This study not only incorporates statistical test-based methods to manage the alignment of mass spectra datasets but also provides a practical means to accomplish rapid strain typing of S. haemolyticus.
关键词： MALDI-TOF MS,strain typing,Fisher’s exact test,Staphylococcus haemolyticus,machine learning
更新于2025-09-16 10:30:52
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[IEEE 2019 European Space Power Conference (ESPC) - Juan-les-Pins, France (2019.9.30-2019.10.4)] 2019 European Space Power Conference (ESPC) - Innovative Temperature Accelerated Life Test for the determination of the activation energy of space solar cells
摘要： Space solar cells have been subjected to an innovative temperature Accelerated Life Test (ALT) to get information on their degradation and their activation energy. Our procedure emulates the thermal stress that solar cells suffer working under space conditions. Solar cells were kept in a climatic chamber under nitrogen atmosphere at three different temperatures for few months. After degradation, results have been fitted to a temperature Arrhenius model, in order to obtain the activation energy and acceleration factor of space GaInP/Ga(In)As/Ge triple junction solar cells.
关键词： accelerated life test,degradation,activation energy,space solar cells,reliability
更新于2025-09-16 10:30:52
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Dielectric Anisotropy Sensor Using Coupled Resonators
摘要： In this article, a new approach is proposed for the measurement of the uniaxial anisotropic dielectric constant of different planar samples by means of a single sensor. The sensor is based on a couple of straight-line coupled resonators in microstrip technology that can be excited in odd and even propagation modes. This sensor is designed on an isotropic substrate at the design frequency. Due to the electric field configuration specific for each mode, it is possible to relate these modes to the dielectric constant in two different directions (parallel and perpendicular) of a dielectric material placed on top of the sensor. This technique is used for the successful characterization of the dielectric constant anisotropic of anisotropic dielectrics (FR4, Rogers 4350B, and Arlon Diclad 880), and the isotropic material PTFE.
关键词： FR4,Anisotropic,dielectric constant,printed circuit board (PCB),uniaxial,anisotropy,sample under test (SUT)
更新于2025-09-16 10:30:52
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In situ gas monitoring by fiber-coupled Raman spectrometry for H2-risk management in nuclear containment during a severe nuclear accident
摘要： An underground nuclear explosion (UNE) can generate a shock wave that lofts surface material, resulting in surface changes that might be detectable. The Comprehensive Nuclear Test-Ban Treaty (CTBT) allows ground and airborne spectral and thermal imaging to help locate such events. Landsat 5 data on the 1998 Indian and Pakistani tests are used here to demonstrate that there are detectable changes in surface features which might be used to localize an underground nuclear test and to develop change detection techniques speci?c to the use of satellite data to support a CTBT on-site inspection. Landsat 5 has been active for over 20 years providing repeat coverage of the Earth’s surface every 16 days. Most locations have Landsat data available for a variety of dates, allowing for statistical analysis of the data to understand temporal trends and data variability on a pixel-by-pixel basis. Given the right conditions, these usual patterns of change (such as seasonal changes or weathering) can be discerned from unusual patterns of change, such as features relating to a UNE. This paper extends known change detection techniques to a temporal series of data and shows that multispectral change detection can be used to help localize a UNE.
关键词： multispectral change detection,Comprehensive Nuclear Test-Ban Treaty (CTBT),covariance matrix Landsat 5,Mahalanobis distance
更新于2025-09-16 10:30:52
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Micromachined Waveguide Interposer for the Characterization of Multi-port Sub-THz Devices
摘要： This paper reports for the first time on a micromachined interposer platform for characterizing highly miniaturized multi-port sub-THz waveguide components. The reduced size of such devices does often not allow to connect them to conventional waveguide flanges. We demonstrate the micromachined interposer concept by characterizing a miniaturized, three-port, 220–330-GHz turnstile orthomode transducer. The interposer contains low-loss micromachined waveguides for routing the ports of the device under test to standard waveguide flanges and integrated micromachined matched loads for terminating the unused ports. In addition to the interposer, the measurement setup consists of a micromachined square-to-rectangular waveguide transition. These two devices enable the characterization of such a complex microwave component in four different configurations with a standard two-port measurement setup. In addition, the design of the interposer allows for independent characterization of its sub-components and, thus, for accurate de-embedding from the measured data, as demonstrated in this paper. The measurement setup can be custom-designed for each silicon micromachined device under test and co-fabricated in the same wafer due to the batch nature of this process. The solution presented here avoids the need of CNC-milled test-fixtures or waveguide pieces that deteriorate the performance of the device under test and reduce the measurement accuracy.
关键词： Test-fixture,Orthomode transducer,Terahertz,Multi-port,Measurement,Interposer,Silicon micromachining,Waveguide,DRIE
更新于2025-09-16 10:30:52
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Feasibility of a point-of-care test based on quantum dots with a mobile phone reader for detection of antibody responses
摘要： We developed a novel and portable fluorescent sensor that integrates a lateral flow assay with a quantum dot (Qdots) label and a mobile phone reader for detection of specific antibodies in human serum. We evaluated the utility of this assay to test for antibodies to the Taenia solium rT24H antigen. It was a retrospective study by examining 112 positive human sera from patients with neurocysticercosis (NCC) including samples from patients with single viable cyst (n = 18), two or more viable cysts (n = 71), and subarachnoid (racemose) cysts (n = 23). These samples were collected from previous study subjects in Lima, Peru that conducted under an approved study protocol in Peru. The sera were made anonymous under a protocol approved by the CDC Institutional Review Board. Definitive diagnosis of the specimen was established by computed-tomography and/or magnetic resonance imaging. To test the specificity of the assay, we evaluated a panel of serum samples obtained from patients with other infections (n = 24), and serum samples from persons in the United States and Egypt who had not traveled outside their country, and therefore are presumed negative for cysticercosis (n = 128). The assay specificity in the negative panel was 99% (95–100%) while assay sensitivity was 89% (79–95%) in NCC patients with two or more viable cysts. Our assay has performance characteristics similar to those of traditional platforms for the detection of NCC and shows promise as a mobile phone reader-based point-of-care test for antibody detection.
关键词： quantum dots,point-of-care test,mobile phone reader,lateral flow assay,neurocysticercosis
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Lasing of the Rhodamine 6G in the Planar Waveguides Formed from Thin Hybrid Films of the Silica and Titania
摘要： The main type of obstacles of practical applications of quantum key distribution (QKD) network are various attacks on detection. Measurement-device-independent QKD (MDIQKD) protocol is immune to all these attacks, and thus, a strong candidate for network security. Recently, several proof-of-principle demonstrations of MDIQKD have been performed. Although novel, those experiments are implemented in the laboratory with secure key rates less than 0.1 b/s. Besides, they need manual calibration frequently to maintain the system performance. These aspects render these demonstrations far from practicability. Thus, justification is extremely crucial for practical deployment into the field environment. Here, by developing an automatic feedback MDIQKD system operated at a high clock rate, we perform a field test via deployed fiber network of 30 km total length achieving a 16.9 b/s secure key rate. The result lays the foundation for a global quantum network, which can shield from all the detection-side attacks.
关键词： measurement-device-independent quantum key distribution,automatic feedback systems,Field test
更新于2025-09-16 10:30:52
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Effects of Stress-Relieving Heat Treatment on Impact Toughness of Direct Metal Laser Sintering (DMLS)-Produced Ti6Al4V (ELI) Parts
摘要： The impact toughness of as-built (AB) and stressed-relieved (SR) direct metal laser sintering-produced Ti6Al4V (ELI) was investigated using the standard Charpy impact test over the temperature range of ?130°C to 250°C. Stress-relieving heat treatment was conducted at 650°C for a soaking period of 3 h in argon gas atmosphere. The results showed improvements in the impact toughness after stress-relieving heat treatment. Stress relieving also shifted the established ductile-to-brittle transition temperature to lower temperatures. Comparative analysis of the impact toughness values for AB and SR specimens at ambient temperature showed them to be 48% and 22% lower than recommended values for use in aircraft structures, respectively.
关键词： Impact Toughness,Stress-Relieving Heat Treatment,Ti6Al4V (ELI),Direct Metal Laser Sintering,Charpy Impact Test
更新于2025-09-12 10:27:22
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Laser‐assisted diagnosis of symptomatic cracks in teeth with cracked tooth: A 4‐year in‐vivo follow‐up study
摘要： The purpose of this study was to determine whether a near-infrared diode laser could be used as an adjunct to help identify and localise symptomatic cracks in patients with cracked tooth. An 810-nm diode laser at 1 W continuous wave energy with a 200 micro-?bre tip was used to scan the offending tooth. Crack identi?ed during the laser scan was removed, restored and reviewed after four weeks and after 4 years. The laser was able to signi?cantly (P = 0.0001) identify suspected cracked teeth from non-cracked control teeth. Of the twelve patients examined, ten participants experienced discomfort as the laser passed over a crack line. At 4-week and 4-year recall, a majority of the ten treated patients responded positively to the management of crack. This study showed that diode laser could be an adjunctive tool for early detection and management of symptomatic cracks with the possibility of improving long-term survival.
关键词： cracked tooth,diode laser,endodontics,vitality test,laser diagnosis
更新于2025-09-12 10:27:22