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Hyperbolic electrode linear ion trap is a good choice as the mass analyzer of miniaturized ion trap mass spectrometer for the reason that it has a compact size and excellent performance. However, ions are ejected from both opposite directions along the x-axis for existing hyperbolic electrode linear ion trap, which means that the ion detection efficiency could not be higher than 50% if only one ion detector is employed in the miniaturized ion trap mass spectrometer. This symmetrical structure significantly influences the analysis performance of hyperbolic electrode linear ion trap and limits the application at miniaturized ion trap mass spectrometer. Therefore, in order to further improve the ion detection efficiency of the ion trap, an asymmetric hyperboloid linear ion trap structure was proposed. By optimizing the unidirectional stretching distance Δra of the x-axis electrode in the direction of ion ejection after the optimization to the stretching distances Δrx of both x axis electrodes, a reasonable asymmetric radio frequency electric field was introduced for improving ion unidirectional ejection efficiency. The samples used in the simulation experiments were ions with m/z 609, 610 and 611. The internal electric field distribution, ion motion trajectory and simulated mass spectra peak of the asymmetric hyperboloid linear ion trap for different electrode structures were analyzed by simulation software SIMION and AXSIM. Then the ion unidirectional ejection efficiency and mass resolution were calculated, and the data were drawn as line charts. The simulation results showed that on the basis of the optimized symmetrical hyperboloid ion trap structure, whose x-axis electrodes were both stretched by Δrx=0.9 mm, an ion unidirectional ejection efficiency of over 90% and a mass resolution over 5 100 for m/z 610 were achieved by optimizing the parameters such as AC frequency and scanning rate, when one of the x-axis electrodes was unidirectionally stretched by Δra=0.8 mm. In addition, under the condition of ions with large m/z 1 890, a mass resolution up to 10 590 and an ion unidirectional ejection efficiency of 93.3% were achieved when Δra=0.7 mm. It proved that the asymmetric hyperboloid linear ion trap with the optimized geometric structure could greatly improve the ion detection efficiency with only one ion detector under the guarantee of high mass resolution, which had a significant advantage for developing miniaturized ion trap mass spectrometer in the future. On the whole, the research could provide a theoretical foundation for further investigations, but there were still some problems to be solved, such as the actual processing, assembly and experiment.

Tuberculosis (TB) is a chronic infectious disease caused by Mycobacterium Tuberculosis (MTB). It is the second largest single cause of death besides novel coronavirus pneumonia. Along with the abuse of antibiotics and extensive use of anti-tuberculosis drugs, multidrug-resistant (MDR) TB, drug-resistant (XDR) TB and totally drug-resistant (TDR) TB became obstacles to the tuberculosis eradication worldwide. According to the World Health Organization (WHO) statistics, China is not only a high burden tuberculosis country in the world, but also a country with a serious epidemic of MDR. Traditional drugs fail to meet the needs of tuberculosis control. Therefore, it is urgent to find new targets of anti-tuberculosis drugs and develop new anti-tuberculosis drugs. Hence, this paper systematically summarizes the mechanism of traditional and newly developed anti-tuberculosis drugs, in which stressing the research progress of drug resistance mechanisms. This work provides us with new insights of new antituberculosis drug developments, and may contribute to a reduction in the harm that tuberculosis brings to society. [ABSTRACT FROM AUTHOR]

The aim of our study was to determine the impact of genetic polymorphisms in the caspase (CASP) genes on prognosis of hepatocellular carcinoma (HCC). We genotyped 7 potentially functional polymorphisms in CASP3, CASP7, CASP8, CASP9, CASP10 genes in 362 HCC patients of receiving surgical resection of HCC tumor. The associations of genotype and haplotype with overall survival (OS) and disease free survival (DFS) were analyzed by using the Cox proportional hazards model. We found that the CASP9 rs4645981 C allele was significantly associated with positive effect on DFS (P = 0.011 and 0.016 for CT+CC vs. TT in univariate and multivariate analysis, respectively), CT genotype was associated with a better OS of HCC than the TT genotype both in univariate and multivariate analysis (P = 0.048 and 0.041, respectively). Moreover, the CASP3 rs2705897 GT genotype showed marginally significant association with decreased OS and DFS, compared with the GG genotype. One haplotype TT/TG in CASP3 (constructed by rs12108497 T>C and rs2705897 T>G) was significantly associated with decreased OS and DFS, compared to the common haplotype TT/TT both in univariate analysis (P = 0.021 and 0.026, respectively) and multivariate analysis (P = 0.025 and 0.030, respectively). The haplotype GT/GT in CASP9 (constructed by rs4645978 A>G and rs4645981 C>T) was significantly associated with decreased DFS both in univariate and multivariate analysis (P = 0.012 and 0.010, respectively). In conclusion, the CASP9 rs4645981 polymorphism, CASP3 and CASP9 haplotypes may be useful prognosis markers for HCC patients with surgical resection of tumor.

Solid‐state NMR analysis on wurtzite alloyed CdSe1−xSx crystalline nanoparticles and nanobelts provides evidence that the 113Cd NMR chemical shift is not affected by the varying sizes of nanoparticles, but is sensitive to the S/Se anion molar ratios. A linear correlation is observed between 113Cd NMR chemical shifts and the sulfur component for the alloyed CdSe1−xSx (0

In this paper, the bed mechanism of the horizontal double-sided combined machine tool is taken as the research target. Firstly, the static and dynamic analysis methods are used to simulate the working state. The equivalent stress and deformation distribution are calculated by static analysis of the bed to judge whether it meets the strength and stiffness requirements or not. Through the modal analysis of the machine bed, the first six natural frequencies and modal mode are obtained to study the dynamic characteristics of the bed working state. Furthermore, the response surface optimization module (Response Surface Optimization) included in the optimization design toolbox of ANSYS Workbench software is used to lighten and optimize the bed structure. By comparing the optimization results before and after, the bed quality of the horizontal double-sided combined machine tool is reduced by 3.36% under the condition that the rigidity of the machine tool is improved or not reduced, and the lightweight optimization design of the horizontal double-sided combined machine tool is realized. [ABSTRACT FROM AUTHOR]

In this paper, an automobile cooling water pump with poor hydraulic performance is taken as the research objective. Orthogonal test optimization design method is adopted to determine the orthogonal design table of L9 (33) and design 9 sets of orthogonal test impeller model schemes. Using ProE software to the original model, 9 groups of test model, the optimized model of 3D modeling, impeller watershed model is set up, and then use pumplinx software of CFD numerical simulation calculation, and analyzes the results of simulation calculation, the geometric parameters of three kinds of factors affect the performance of hydraulic pump, and determine the final optimal combination. The test results show that the head of optimized model has an increase of 6.364 meters and the efficiency is increased by 0.02% than the original model. The excellent optimization results are obtained, and the feasibility of orthogonal test applied to the optimal design of pump hydraulic performance is verified. [ABSTRACT FROM AUTHOR]

Magnetic materials were recently developed for sludge disposal because of their advantages. However, the role of magnetic materials in the process of anaerobic digestion of municipal dewatered sludge remains unclear. The aim of this present study is to investigate the magnetic effect factors such as static magnetic field, magnetic nanoparticles, and ordinary magnetic particles on the anaerobic digestion of municipal dewatered sludge. In addition, the biogas production variations and relevant physicochemical properties of municipal dewatered sludge under anaerobic digestion are also evaluated by adding anaerobic bacteria. Results indicated that the magnetic nanoparticles are superior to both ordinary magnetic particles and static magnetic field at total biogas production; moreover, the aerobic bacteria could shorten the duration of anaerobic digestion. For the sludge dewatering, the organic matter degradation rate, chemical oxygen demand degradation rate, and dewatering rate under the treatment condition with magnetic nanoparticles are 32.1%, 87.1%, and 70.9%, respectively. It is suggested that the magnetic nanoparticles are much suitable for sludge dewatering than ordinary magnetic particles. As combined with bacteria, magnetic nanoparticles can effectively increase gas output, methane content, and shorten the anaerobic digestion period. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 374–379, 2019 [ABSTRACT FROM AUTHOR]