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BackgroundThe silicon photomultiplier (SiPM) is sensitive to environmental noise, its performance is greatly affected by ambient noise.PurposeThis study aims to design a negative-feedback selective amplifier circuit for SiPM coupled plastic scintillator detector to reduce the noise and improve the overall performance of SiPM.MethodsIt is compared with the traditional OPA657 transimpedance feedback amplifier circuit. The circuit consisted of an RC filter input and an integrated operational amplifier AD8014 with advantages of a high gain and low input noise. The CR high-pass filter circuit was used as the comparator signal input to further filter out signal noise and prevent signal reflection from interfering with the amplifier. The experimental circuit is simulated using Micro-cap12 to obtain the relevant circuit parameters. Finally, the dark noise level and signal consistency of a 137Cs source at room temperature was record, and performance of this amplifier circuit for SiPM coupled plastic scintillator detector was compared with that of the traditional OPA657 transimpedance feedback amplifier circuit. [Results and Conclusions] Comparison results show that the proposed circuit effectively filters out ambient noise and exhibits a fast rise time. The output pulse rise time is found to be less than 12 ns, and the dark noise level is observed to be less than 30 mV, which are better than those of the transimpedance amplifier circuit.

In recent years, cosmic ray muon tomography technology has attracted extensive attention. It uses natural muons as the radiation source. Because of the high penetration ability and sensitivity to high-Z materials, cosmic ray muon tomography can realize nondestructive inspection of special nuclear materials. Therefore, it has broad application prospects in the field of container detection such as border defense and ports. Multiple Coulomb scattering occurs when muons pass through materials, and the scattering angle distribution is related to the atomic number of the material. In practical applications, such as container or cargo material smuggling detection and other scenes requiring timeliness, sometimes it is not necessary to get accurate reconstruction images, but only need to realize the discrimination of high atomic number materials in a relatively short time, and give an alarm. In view of this, we proposed a method to quickly realize material discrimination based on only a small amount of cosmic ray muon data without reconstructing the image, so as to better meet the needs of practical application scenarios. The machine learning method of convolutional neural network was applied first for material discrimination in muon tomography and the optimal model was obtained through processing the training data iteratively, and finally the results of the accuracy of material discrimination and its relation with the measurement time used were obtained. Above all, the Geant4 Monte Carlo simulation program was established. To simulate the real detection environment as much as possible, the natural source term of cosmic rays was introduced, and the models of the detector and the materials to be detected were built according to the actual size of the muon tomography facility. Further, the detection experiments of different materials were carried out at the muon tomography facility for special material tracking in China Institute of Atomic Energy, the muon tracks were reconstructed from the measured data, and the incidence and the scattering angles were calculated. The material discrimination model based on convolutional neural network was constructed for feature extraction to realize the classification and discrimination, and the residual error and the feature matrix were introduced to improve the accuracy of material discrimination. The experimental results show that, for the tungsten block with the size of 10 cm×10 cm×10 cm, the accuracy of material discrimination is up to 99.1% in 5 minutes’ measurement and 100.0% in 10 minutes’ measurement. This method based on convolutional neural network provides a new approach for material discrimination in muon scattering tomography.

Objective: To conduct a comprehensive data analysis based on the FDA's Adverse Event Reporting System (FAERS) to mine possible adverse event (AE) signals of Capmatinib, providing valuable references for its clinical application. Methods: Capmatinib was the primary suspected drug in the search of FAERS database from the second quarter of 2020 to the fourth quarter of 2023. Data processing, screening, and classification were performed using methods such as the Reporting Odds Ratio (ROR), Proportional Reporting Ratio (PRR), Bayesian Confidence Propagation Neural Network (BCPNN), and Multi-item Gamma Poisson Shrinker (MGPS). Results: A total of 1,991 AE reports directly related to Capmatinib were screened, identifying 269 Preferred Terms (PTs) involving 26 System Organ Classes (SOCs). Besides the AEs recorded in the drug label (such as edema, nausea, fatigue, and dyspnea), the study unearthed other high-risk AEs not listed in the label, including Renal and urinary disorders, Vocal cord paralysis, and Ear and labyrinth disorders. Among these, renal and urinary disorders, and ear and labyrinth disorders had a higher frequency and intensity of signals, suggesting that their mechanisms of occurrence could be a future research direction. Conclusion: This study uncovered new potential AEs of Capmatinib based on the FAERS database, providing reference for its safe clinical use. Special attention should be given to the occurrence of ear and labyrinth disorders and renal and urinary disorders, primarily presenting as pseudo-acute kidney injury, during treatment. [ABSTRACT FROM AUTHOR]

After γ-ray irradiation treatment, a monolayer tungsten diselenide could be transitioned into an n-doped semiconductor due to the anion vacancies created by the radiation. Transmission electron microscope studies showed clear chemical modulation with atomically sharp interface. Change in the lattice vibrational modes induced by passivation of oxygen is captured by Raman spectroscopy. The frequency shifts in both in-plane and out-of-plane modes are dependent linearly on the oxidation content. We observe a negative trion, which is a neutral exciton bound with an electron, in the photoluminescence spectra. The binding energy of this trion is estimated to be ∼90 meV, making it a tightly bound exciton. The first-principles calculation suggests that an increase in the anion vacancy population is generally accompanied by a transition from a direct gap material to an indirect one. This opens up a new venue to engineer the electronic properties of transition metal dichalcogenides by using irradiation. [ABSTRACT FROM AUTHOR]

Biomolecular machines autonomously convert energy into functions, driving systems away from thermodynamic equilibrium. This energy conversion is achieved by leveraging complex, kinetically asymmetric chemical reaction networks that are challenging to characterize precisely. In contrast, all known synthetic molecular systems in which kinetic asymmetry has been quantified are well described by simple single‐cycle networks. Here, we report on a unique light‐driven [2]rotaxane that enables the autonomous operation of a synthetic molecular machine with a multi‐cycle chemical reaction network. Unlike all prior systems, the present one exploits a photoactive macrocycle, which features a different photoreactivity depending on the binding sites at which it resides. Furthermore, E to Z isomerization reverses the relative affinity of the macrocycle for two binding sites on the axle, resulting in a multi‐cycle network. Building on the most recent theoretical advancements, this work quantifies kinetic asymmetry in a multi‐cycle network for the first time. Our findings represent the simplest rotaxane capable of autonomous shuttling developed so far and offer a general strategy to generate and quantify kinetic asymmetry beyond single‐cycle systems. [ABSTRACT FROM AUTHOR]

After γ-ray irradiation treatment, a monolayer tungsten diselenide could be transitioned into an n-doped semiconductor due to the anion vacancies created by the radiation. Transmission electron microscope studies showed clear chemical modulation with atomically sharp interface. Change in the lattice vibrational modes induced by passivation of oxygen is captured by Raman spectroscopy. The frequency shifts in both in-plane and out-of-plane modes are dependent linearly on the oxidation content. We observe a negative trion, which is a neutral exciton bound with an electron, in the photoluminescence spectra. The binding energy of this trion is estimated to be ∼90 meV, making it a tightly bound exciton. The first-principles calculation suggests that an increase in the anion vacancy population is generally accompanied by a transition from a direct gap material to an indirect one. This opens up a new venue to engineer the electronic properties of transition metal dichalcogenides by using irradiation. [ABSTRACT FROM AUTHOR]