The bipolar charge plasma spectrometer (BCPS) based on the 2π-field-of-view double-channel electrostatic analyzer.

In this paper, we propose a bipolar charge plasma spectrometer based on the double-channel electrostatic analyzer for simultaneously measuring thermal ions and electrons with a 2π hemispherical field-of-view. Both ions and electrons within the wide field-of-view enter the spectrometer, pass through the variable geometric factor channel, and are then separated by the double-channel electric fields. Two microchannel plates are accommodated at the exit of the analyzer for ion and electron detection. The main performance of the spectrometer has been obtained from on-ground calibration. With the electrostatic deflectors and the cylindrically symmetric structure, the spectrometer provides simultaneous measurements of thermal ion and electron velocity distributions with a shared field-of-view of 360° (azimuth angle) by 90° (elevation angle) and a broad energy range for both ions and electrons. The ion analyzer constant and the electron analyzer constant are 11.1 and 9.7, respectively. The detecting energy range of 33.3-44.4 keV for ions and 29.1-38.8 keV for electrons can be obtained by using the sweeping electrostatic analyzer voltage range of 3-4000 V. The ion and electron energy resolutions are 9.6% and 6.1%, respectively. The variable geometric factor function provides a large geometric factor adjusting range for both ion and electron measurements by two orders of magnitude, which fulfills the requirements of a large dynamic flux range for simultaneous measurements of space thermal plasma in the solar wind and magnetosphere.

Seasonal concentrations, contamination levels, and health risk assessment of arsenic and heavy metals in the suspended particulate matter from an urban household environment in a metropolitan city, Beijing, China.

The levels and health risks of arsenic and heavy metals (As, Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) in the suspended particulate matter (SPM) collected from an urban household environment in Beijing of China for 12 months were investigated. The mean concentrations of the studied toxic elements were higher and lower than crustal abundance and PM2.5 in the urban outdoors of Beijing. The concentrations of the studied elements displayed significant seasonality. The highest concentrations of the total elements occurred in winter, followed by autumn, while the lowest concentrations were recorded in summer. Based on the calculated values of enrichment factor (EF) and geoaccumulation index (Igeo), the levels for As and Cu were heavily contaminated, while those for Cd, Pb, and Zn were extremely contaminated. As and Pb might pose risks to children and adults via ingestion exposure. The accumulative risks of multi-elements resulted from dermal contact and inhalation exposures were not negligible. More attention should be paid to reducing the non-carcinogenic and carcinogenic health risks posed by the toxic elements bound to urban household SPM particles via ingestion, inhalation, and dermal contact exposure.

A pregnant mouse model for the vertical transmission of Brucella melitensis.

Abortion is the major clinical sign of brucellosis in animals but little is known about the underlying mechanisms. This study was designed to evaluate a pregnant mouse model for the vertical transmission of Brucella melitensis using four infectious doses: 10(3) colony-forming units (CFU), 10(4) CFU, 10(5) CFU, and 10(6) CFU. During the experimental period, no instances of abortion were recorded, but stillbirths were observed in the groups infected with doses of 10(4) CFU and higher. Regardless of whether the fetuses were stillborn or alive, transmission of bacteria to the fetus and bacterial replication in the cytoplasm of placental trophoblast giant cells were detected. A higher degree of bacterial colonization was found in the placenta than in the spleen or fetus. Doses of 10(5) CFU of B. melitensis or higher produced a severe, necrotizing placentitis similar to the pathological damage observed in ruminants. The data suggest that experimental murine brucellosis resembles ruminant brucellosis and represents a potential model for studying the pathogenic mechanisms of B. melitensis.

Prediction of RNA-binding proteins by voting systems.

It is important to identify which proteins can interact with RNA for the purpose of protein annotation, since interactions between RNA and proteins influence the structure of the ribosome and play important roles in gene expression. This paper tries to identify proteins that can interact with RNA using voting systems. Firstly through Weka, 34 learning algorithms are chosen for investigation. Then simple majority voting system (SMVS) is used for the prediction of RNA-binding proteins, achieving average ACC (overall prediction accuracy) value of 79.72% and MCC (Matthew's correlation coefficient) value of 59.77% for the independent testing dataset. Then mRMR (minimum redundancy maximum relevance) strategy is used, which is transferred into algorithm selection. In addition, the MCC value of each classifier is assigned to be the weight of the classifier's vote. As a result, best average MCC values are attained when 22 algorithms are selected and integrated through weighted votes, which are 64.70% for the independent testing dataset, and ACC value is 82.04% at this moment.