Research of the Algebraic Multigrid Method for Electron Optical Simulator.

At present, electron optical simulator (EOS) takes a long time to solve linear FEM systems. The algebraic multigrid preconditioned conjugate gradient (AMGPCG) method can improve the efficiency of solving systems. This paper is focused on the implementation of the AMGPCG method in EOS. The aggregation-based scheme, which uses two passes of a pairwise matching algorithm and the K-cyle scheme, is adopted in the aggregation-based algebraic multigrid method. Numerical experiments show the advantages and disadvantages of the AMG algorithm in peak memory and solving efficiency. The AMGPCG is more efficient than the iterative methods used in the past and only needs one coarsening when EOS computes the particle motion trajectory.

Mode analysis in a conceptual hybrid simulation model for efficient ECRIS simulations.

Numerical simulation has played an important role in the development of the electron cyclotron resonance ion source (ECRIS) as it can compensate for the limitations of experiment studies. However, the complex process during the ECRIS operation also brings a lot of difficulties to simulations. One of the biggest problems is the compromise between accuracy and computational costs. To satisfy the needs of simulation accuracy and speed, we have considered a hybrid simulative model: mode representative particle-in-cell/Monte Carlo collision (MPM). In this work, the self-consistent description of the interactions between plasma and electromagnetic fields in the MPM model is introduced with the mode analysis. Mode contributions to the global field are analyzed and an analytical treatment on infinite evanescent modes is validated. It makes the hybrid MPM model applicable for practical ECRIS simulations.

3D particle-in-cell simulations of electron magnetic confinement in electron cyclotron resonance ion sources.

The electron confinement in an electron cyclotron resonance ion source is considered a critical factor that has a great influence on the working efficiency. In this paper, a three-dimensional electromagnetic particle-in-cell code is presented for simulations of the electron confinement in minimum-B structures. Electron dynamics under the effect of electromagnetic fields is modeled through a leapfrog scheme by solving Maxwell's equations and the particle equations of motion iteratively. Some characteristics of electron magnetic confinement are obtained through a benchmarking example. Preliminary results of the simulation show good agreement with the well-known effects.

Expression of P-gp, MRP, LRP, GST-π and TopoIIα and intrinsic resistance in human lung cancer cell lines.

This study aimed to determine the relationship between the endogenous levels of P-glycoprotein (P-gp), multidrug resistance-associated protein (MRP), lung resistance-related protein (LRP), glutathione-s-transferase-π (GST­π) and topoisomerase IIα (TopoIIα) and intrinsic drug resistance in four human lung cancer cell lines, SK-MES-1, SPCA-1, NCI-H-460 and NCI-H-446, of different histological types. The expression of P-gp, MRP, LRP, GST-π and TopoIIα was measured by immunofluorescence, Western blotting and RT-PCR. Drug resistance to cisplatin, doxorubicin and VP-16 was determined using MTT assays. The correlation between expression of the resistance-related proteins and their roles in the resistance to drugs in these cancer cell lines was analyzed. We found that the endogenous levels of P-gp, MRP, LRP, GST-π and TopoIIα in the four cell lines varied. The level of GST-π in the SK-MES-1 cells was the highest, whereas the level of P-gp in the SPCA-1 cells was the lowest. The chemoresistance to cisplatin, doxorubicin and VP-16 in the four cell lines was different. The SPCA-1 cell line was most resistance to cisplatin; SK-MES-1 was most resistance to VP-16; whereas SK-MES-1 was most sensitive to doxorubicin. There was a positive correlation between GST-π expression and resistance to cisplatin, between TopoIIα expression and resistance to VP-16; and a negative correlation was noted between TopoIIα expression and resistance to doxorubicin. In summary, the endogenous expression of P-gp, MRP, LRP, GST-π and TopoIIα was different in the four human lung cancer cell lines of different histological types, and this variance may be associated with the variation in chemosensitivity to cisplatin, doxorubicin and VP-16. Among the related proteins, GST-π may be useful for the prediction of the intrinsic resistance to cisplatin, whereas TopoIIα may be useful to predict resistance to doxorubicin and VP-16 in human lung cancer cell lines.

Field emission from few-layer graphene nanosheets produced by liquid phase exfoliation of graphite.

Graphene nanosheets have been synthesized from commercial expandable graphite by heating in a microwave oven and dispersing in ethanol by ultrasonication. Scanning and transmission electron microscopy and electron energy-loss spectroscopy and atomic force microscope showed that the nanosheets were about 2 nm in thickness and 10 microm in diameter. The field emission of the graphene sheets has been investigated. An emission current density of 1 mA/cm2 has been achieved at an electric field of 3.7 V/microm with a turn-on field of 1.7 V/microm at 0.01 mA/cm2. The annealing of the samples at 400 degrees C in vacuum greatly improved the field emission performance.

Down-regulation of P-glycoprotein is associated with resistance to cisplatin and VP-16 in human lung cancer cell lines.

AIM: To investigate whether down-regulation of P-glycoprotein (P-gp) is correlated to resistance to cisplatin and VP-16 in four histopathological subtype cell lines of lung cancer (SK-MES-1, SPCA-1, NCI-H-460 and NCI-H-446). MATERIALS AND METHODS: After pretreatment with or without verapamil, the P-gp expression was examined by means of RT-PCR and immunofluorescence. Cell survival on treatment with cisplatin and VP-16 was determined by MTT assay. RESULTS: The expression of P-gp was clearly inhibited by verapamil in all four cell lines. Following pretreatment with verapamil, NCI-H-446 was more sensitive to cisplatin, while SPCA-1, NCI-H-460 and NCI-H-446 were more sensitive to VP-16 compared to the control. CONCLUSION: Down-regulation of P-gp is associated with intrinsic resistance to cisplatin in the NCI-H-446 and to VP-16 in SPCA-1, NCI-H-460 and NCI-H-446 cell lines. These findings indicate that down-regulation of P-gp may be helpful for the reversion of drug resistance in some lung cancer cell line subtypes.