摘要：An electrostatic accelerating column was designed and fabricated by Lanzhou University for an intense D-T/D-D neutron generator. In order to achieve a neutron yield of 5.0�1012 n/s, a deuteron beam of 30 mA, accelerated to 400 kV, and transported in the electrostatic accelerating column smoothly are required. One particle-in-cell code BEAMPATH was used to simulate the beam transport, and the IONB1.0 code was used to simulate the intense beam envelopes. Emittance growths due to space charge effect and spherical aberration were analyzed. The simulation results show that the accelerating column can transport deuteron beam of 30 mA smoothly and the requirement for the neutron generator is satisfied.
摘要：Direct demodulation method (DDM) was applied to reconstruct γ-ray spectra. Boosted Richardson-Lucy iteration was introduced into DDM. Monte Carlo method (here GEANT 4) was proposed to calibrate response function and establish response matrix. First, gauss function was regarded as total energy peak. Spectra line was simulated with nine gauss functions. And afterwards DDM was applied to reconstruct the simulated spectra line and determine peak positions and areas. Compared with original spectra, for case that peak position interval was about 1/3 full width half maximum (FWHM), the error of rebuilding peak position was 2 channels. The rest of peaks could be searched accurately. The relative errors of all peaks’ area were less than 4%. Then, three key factors, including noise, background, response matrix, were discussed. Finally, DDM was applied to calibrate the field NaI gamma spectrometer. The errors of U, Th, K were less than 5%. Comprehensive studies have shown that it is feasible to reconstruct gamma-ray spectra with DDM. DDM can significantly pseudo-improve energy resolution of gamma spectrometer, effectively decompose doublets whose peak potential interval is 1/3 FHWM, and accurately search peak and calculate areas. DDM can restrain noise strongly but is greatly influenced by background. And DDM can improve the accuracy of qualitative and quantitative analysis in combination with the conventional spectrum analysis method.
摘要：In this paper, we study hydrodynamics and thermal behaviors of micro-heat exchanger of different cross sections, with hydraulic diameters (Dh) of 0.4–0.8 mm and Reynolds numbers (Re) of 300–900. Validity of the model is proved by comparing simulation results based on classical Navier-Stokes equations with experimental data and Tuckerman correlation. Effects of dynamic viscosity, hydraulic diameter, Reynolds number and cross section of the micro-channels are investigated. The results indicate that the variable viscosity effect should be taken into account, and rod bundle micro-channels have the highest heat transfer coefficient of the three types of micro-channels.
摘要：In energy dispersive X-ray fiuorescence (EDXRF), quantitative elemental content analysis becomes difficult due to the existence of the noise, the spectrum peak superposition, element matrix effect, etc. In this paper, a hybrid approach of genetic algorithm (GA) and back propagation (BP) neural network is proposed without considering the complex relationship between the elemental content and peak intensity. The aim of GA-optimized BP is to get better network initial weights and thresholds. The starting point of this approach is that the reciprocal of the mean square error of the initialization BP neural network is set as the fitness value of the individuals in GA; and the initial weights and thresholds are replaced by individuals, then the optimal individual is searched by selecting, crossover and mutation operations, finally a new BP neural network model is established with the optimal initial weights and thresholds. The quantitative analysis results of titanium and iron contents in five types of mineral samples show that the relative errors of 76.7% samples are below 2%, compared to chemical analysis data, which demonstrates the effectiveness of the proposed method.
摘要：Recent reactor antineutrino experiments have observed that the neutrino spectrum changes with the reactor core evolution and that the individual fissile isotope antineutrino spectra can be decomposed from the evolving data, providing valuable information for the reactor model and data inconsistent problems. We propose a machine learning method by building a convolutional neural network based on a virtual experiment with a typical short-baseline reactor antineutrino experiment configuration: by utilizing the reactor evolution information, the major fissile isotope spectra are correctly extracted, and the uncertainties are evaluated using the Monte Carlo method. Validation tests show that the method is unbiased and introduces tiny extra uncertainties.
摘要：Lakes play important roles in sustaining the ecosystem and economic development in Inner Mongolia Autonomous Region of China, but the spatial patterns and driving mechanisms of water quality in lakes so far remain unclear. This study aimed to identify the spatial changes in water quality and the driving factors of seven lakes (Juyanhai Lake, Ulansuhai Lake, Hongjiannao Lake, Daihai Lake, Chagannaoer Lake, Hulun Lake, and Wulannuoer Lake) across the longitudinal axis (from the west to the east) of Inner Mongolia. Large-scale research was conducted using the comprehensive trophic level index (TLI (Σ)), multivariate statistics, and spatial analysis methods. The results showed that most lakes in Inner Mongolia were weakly alkaline. Total dissolved solids and salinity of lake water showed obvious zonation characteristics. Nitrogen and phosphorus were identified as the main pollutants in lakes, with high average concentrations of total nitrogen and total phosphorus being of 4.05 and 0.21 mg/L, respectively. The values of TLI (Σ) ranged from 49.14 to 71.77, indicating varying degrees of lake eutrophication, and phosphorus was the main driver of lake eutrophication. The lakes of Inner Mongolia could be categorized into lakes to the west of Daihai Lake and lakes to the east of Daihai Lake in terms of salinity and TLI (Σ). The salinity levels of lakes to the west of Daihai Lake exceeded those of lakes to the east of Daihai Lake, whereas the opposite trend was observed for lake trophic level. The intensity and mode of anthropogenic activities were the driving factors of the spatial patterns of lake water quality. It is recommended to control the impact of anthropogenic activities on the water quality of lakes in Inner Mongolia to improve lake ecological environment. These findings provide a more thorough understanding of the driving mechanism of the spatial patterns of water quality in lakes of Inner Mongolia, which can be used to develop strategies for lake ecosystem protection and water resources management in this region.
摘要： The chest X-Ray (CXR) is the one of the most common clinical exam used to diagnose thoracic diseases and abnormalities. The volume of CXR scans generated daily in hospitals is huge. Therefore, an automated diagnosis system that is able to save the effort of doctors is of great value. At present, the applications of artificial intelligence in CXR diagnosis usually use pattern recognition to classify the scans. However, such methods rely on labeled databases. They are costly and usually have a high error rate. In this work, we built a database containing more than 12,000 CXR scans and radiological reports, and developed a model based on deep convolutional neural network and recurrent network with attention mechanism. The model learns features from the CXR scans and the associated raw radiological reports directly; no additional labeling required. The model provides automated recognition of given scans and generation of impression. The quality of the generated impression was evaluated with both the CIDEr scores and by radiologists as well. The CIDEr scores were found to be around 5.8 on average for the testing dataset. Further blind evaluation suggested a comparable performance against radiologists.
摘要：Linear and hyperbranched poly(azomethine)s (PAMs)-based on tri- phenylamine moieties are synthesized and used as the functioning layers in the Ta/PAM/Pt resistive switching memory devices. Com- parably, the hyperbranched PAM with isotropic architecture and semi-crystalline nature shows enhanced memory behaviors with more uniform distribution of the HRS and LRS resistances.
摘要：Thermally stable poly(triphenylamine) (PTPA) synthesized by an oxidative coupling reaction is used as the functional layer in memory devices, which exhibit non-volatile bistable resistive switching behavior with a large ON/OFF ratio over 5 108, a long retention time exceeding 8 103 s and a wide working temperature range of 30–390 K.
摘要：Shear bands play a key role in the plastic deformation of metallic glasses [MGs]. Even though there are extensive studies on the initiation and propagation of shear bands, the interactions among them have not been systematically studied yet. The interacti
摘要：Previously reported studies have demonstrated the involvement of p21(Waf1/CIP1) in radiation-induced bystander effects (RIBE). Mouse embryonic fibroblasts (MEFs) lacking Hus1 fail to proliferate in vitro, but inactivation of p21 allows for the continued growth of Hus1-deficient cells, indicating the close connection between p21 and Hus1 cells. In this study, wildtype MEFs, Hus1(+/+)p21(-/-) MEFs and p21(-/-)Hus1(-/-) MEFs were used in a series of radiation-induced bystander effect experiments, the roles of p21 and Hus1 in the induction and transmission of radiation-induced damage signals were investigated. Our results showed that after 5 cGy alpha particle irradiation, wild-type MEFs induced significant increases in gamma-H2AX foci and micronuclei formation in bystander cells, whereas the bystander effects were not detectable in p21(-/-)Hus1(+/+) MEFs and were restored again in p21(-/-)Hus1(-/-) MEFs. Media transfer experiments showed that p21(-/-)Hus1(+/+) MEFs were deficient in the production bystander signals, but could respond to bystander signals. We further investigated the mitogen-activated protein kinases (MAPKs) that might be involved in the bystander effects. It was found that although knocking out p21 did not affect the expression of connexin43 and its phosphorylation, it did result in inactivation of some MAPK signal pathway kinases, including JNK1/2, ERK1/2 and p38, as well as a decrease in reactive oxygen species (ROS) levels in irradiated cells. However, the activation of MAPK kinases and the ROS levels in irradiated cells were restored in the cell line by knocking out Hus1. These results suggest that p21(Waf1/CIP1) and Hus1 play crucial roles in the generation and transmission of bystander damage signals after low-dose a particle irradiation. (C) 2015 by Radiation Research
摘要：Glycosylation is one of the most common and important post-translational modifications of proteins. Identification of large-scale N-linked glycoprotein is a very important aspect in glycoproteomics research. The N-glycopeptide enrichment is a key step in high-throughput identification of N-glycosylation site. Lectin enrichment and hydrazide chemistry are the two widely used N-glycopeptides enrichment methods. Each method can only enrich certain types of glycopeptides. It has been reported that the two methods are highly complementary, but few studies compared overlaps of glycosties from the two methods. In this paper, using HepG2 cells, we systematically compared the performance of hydrazide chemistry and lectins enrichment methods. The results showed that although the hydrazide method with glycopeptides enrichment efficiency of 76.7%, far higher than the 54.6% lectin enrichment method, 825 glycoprotein and 1 879 N-glycosylation sites identified with the lectin method was significantly more than 522 glycoprotein and 1 014 glycosylation sites enriched by the hydrazide method. Moreover, the two methods did not show significant complementary, together, only 853 glycoproteins and 1 959 N-glycosylation sites were identified. The overlapping results of identified N-glycosylation sites and N-glycoproteins from the two methods show that lectins enrichment method was better than hydrazide chemistry method.
摘要：Calstabin2, also named FK506 binding protein 12.6 (FKBP12.6), is a subunit of ryanodine receptor subtype 2 (RyR2) macromolecular complex, which is an intracellular calcium channel and abundant in the brain. Previous studies identified a role of leaky neuronal RyR2 in posttraumatic stress disorder (PTSD). However, the functional role of Calstabin2 in the cognitive function remains unclear. Herein, we used a mouse model of genetic deletion of Calstabin2 to investigate the function of Calstabin2 in cognitive dysfunction. We found that Calstabin2 knockout (KO) mice showed significantly reduced performance in Morris Water Maze (MWM), long-term memory (LTM) contextual fear testing, and rotarod test when compared to wild type (WT) littermates. Indeed, genetic deletion of Calstabin2 reduced long-term potentiation (LTP) at the hippocampal CA3-CA1 connection, increased membrane excitability, and induced RyR2 leak. Finally, we demonstrated that the increase in cytoplasmic calcium activated Ca2+ dependent potassium currents and led to neuronal apoptosis in KO hippocampal neurons. Thus, these results suggest that neuronal RyR2 Ca2+ leak due to Calstabin2 deletion contributes to learning deficiency and memory impairment.