ELECTRON TRANSPORT BEHAVIOURS IN THE NITROGEN DIRECT CURRENT GLOW DISCHARGE

A Monte Carlo simulation is presented to describe the electron transport behaviours in the nitrogen direct current glow discharge. The energy and angular distributions of the electrons at different positions of the cathode dark space are calculated; their energy and density distribution features throughout the entire discharge are discussed. The influence of molecular vibrational excitation, typical for electron－molecule collisions, has been studied and the elementary process of active species generation has been illustrated. The simulated results reveal that, in the cathode dark space, the high-energy electrons are mainly forward scattering and behave as a high-energy ‘electron beam'. The sharp increase of the number of secondary electrons plays an important role in producing active species at the interface between the cathode dark space and the negative glow region. The vibrational excitation enhances the energy loss of electrons in the negative glow region.     

单重态氧发生器出口气流中水汽含量的光谱测量法

水汽的含量是化学法单重态氧发生器（ＳＯＧ）的重要性能参数之一，因为它不仅对Ｏ＿２（￣１△）有猝灭作用，而且在氧碘化学激光器（ＣＯＩＬ）光腔中对Ｉ￣＊也有严重猝灭作用。因此测控ＳＯＧ出口处的水汽含量有重要意义。本实验采用光谱强度比较法测量ＳＯＧ中的水汽含量，利用ＯＭＡ－３的二维扫描积累功能，可对不同测点的光谱进行同时扫描积累，从而可以对ＳＯＧ的数个测点同时进行水汽含量测定。测试精度可达±１０％。     

Interaction of Au nanowires with impurities

We report the results of our first-principles studies of the interaction between an infinite monoatomic gold nanowire and a carbon-monoxide molecule. We show that the gold monoatomic nanowire is capable of absorbing the CO molecule at the distances of about 1.8 ? and forms a bond with the carbon atom. Further, we find that dissociation of the CO molecule as the source of gold nanowire contamination with carbon, which is widely discussed in literature as the possible reason for the striking stability of gold nanowires under stretching, is thermodynamically unfavored.     

Studies on the electrochemiluminescent behavior of luminol on indium tin oxide (ITO) glass

The electrochemiluminescence (ECL) of luminol on indium tin oxide (ITO) glass was high even under a low potential around 0.4-0.5 V, which was quite different from other electrodes such as platinum. ITO nanoparticles were synthesized and used in the research on ITO glass in the ECL process. A static interaction between ITO and luminol is confirmed from UV-vis and fluorescence spectra. Then the ECL enhancement can be supposed to originate from the adsorption of luminol on ITO, which facilitated luminol’s oxidization to the excited state, giving out ECL. On the other hand, ITO can catalyze the generation of reactive oxygen species (ROSs), similar to some other nanomaterials, which also favored the ECL enhancement of luminol.     

Quantitative Detection of Superoxide Ions in Whole Blood of the American Alligator (Alligator mississippiensis)

WST-1 and nitroblue tetrazolium (NBT) were used to quantify production of superoxide ions by leukocytes of the American alligator in whole blood. Because of the difficulty of isolating healthy leukocytes in alligators, these compounds were employed in whole blood instead of leukocyte preparations commonly used in other studies. The detection of superoxide was concentration- and time-dependent and linear with serial dilutions of whole blood. WST-1 reduction was inhibited by superoxide dismutase, indicating that the reduction was due to the presence of superoxide. Light microscopy revealed that superoxide production occurred in leukocytes, with no detectable contributions from other blood components.     

Formation and Evolution of Carbonate Species in Na-Doped Al2O3 and V2O5-Al2O3

A study is carried out by FT-IR spectroscopy of the carbonate species formed upon interaction of CO₂ with alumina and vanadia-alumina catalysts doped with sodium. It is found that the presence of sodium enhances the ability of the catalyst surface to adsorb CO₂, yielding to carbonate formation. The species formed changes in the presence of vanadium, shifting the ν_COO stretching bands towards higher wavenumbers than those recorded in Na-Al₂O₃ systems.     

Computational modelling of multi-material energetic materials and systems

ABSTRACT

In this paper, we present a systematic roadmap for developing a robust and parallel multi-material reactive hydrodynamic solver that integrates historically stable algorithms with new and current modern methods to solve explosive system design problems. The Ghost Fluid Method and Riemann solvers were used to enforce appropriate interface boundary conditions. Improved performance in terms of computational work and convergence properties was achieved by modifying a local node sorting strategy that decouples ghost nodes, allowing us to set material boundary conditions via an explicit procedure, removing the need to solve a coupled system of equations numerically. The locality and explicit nature of the node sorting concept allows for greater levels of parallelism and lower computational cost when populating ghost nodes. Non-linear numerical issues endemic to the use of real Equations of State in hydro-codes were resolved by using more thermodynamically consistent forms allowing us to accurately resolve large density gradients associated with high energy detonation problems at material interfaces. Pre-computed volume tables were implemented adding to the robustness of the solver base.     

New insights on the role of ROS in the mechanisms of sonoporation-mediated gene delivery

Reactive oxygen species (ROS) are hypothesized to play a role in the sonoporation mechanisms. Nevertheless, the acoustical phenomenon behind the ROS production as well as the exact mechanisms of ROS action involved in the increased cell membrane permeability are still not fully understood. Therefore, we investigated the key processes occurring at the molecular level in and around microbubbles subjected to ultrasound using computational chemistry methods. To confirm the molecular simulation predictions, we measured the ROS production by exposing SonoVue® microbubbles (MBs) to ultrasound using biological assays. To investigate the role of ROS in cell membrane permeabilization, cells were subjected to ultrasound in presence of MBs and plasmid encoding reporter gene, and the transfection level was assessed using flow cytometry. The molecular simulations showed that under sonoporation conditions, ROS can form inside the MBs. These radicals could easily diffuse through the MB shell toward the surrounding aqueous phase and participate in the permeabilization of nearby cell membranes. Experimental data confirmed that MBs favor spontaneous formation of a host of free radicals where HO was the main ROS species after US exposure. The presence of ROS scavengers/inhibitors during the sonoporation process decreased both the production of ROS and the subsequent transfection level without significant loss of cell viability. In conclusion, the exposure of MBs to ultrasound might be the origin of chemical effects, which play a role in the cell membrane permeabilization and in the in vitro gene delivery when generated in its proximity.     

火灾烟气危害性气体在狭长通道内水平方向迁移的模拟实验研究

利用狭长通道的小型实验台模拟研究了火灾烟气毒性成分在水平方向上的迁移规律.结果发现,火灾烟气危害性成分水平方向上的演变非常相似,而不同高度水平面上的烟气成分浓度有些差别,这主要是建筑结构中各种开口或者空气流动造成的.数据表明,CO等气体到达浓度峰值的时间随着高度的降低而逐渐增加.其中,O2和CO2到达峰值的时间比较一致,而CO则与前两者不一致,整体滞后80秒左右,这可能因为热烟气在传播过程又新生成了CO.     

Special features of the EPR spectroscopy of a system of centers with different relaxation times

We found that the interaction of paramagnetic centers that have different relaxation times differs fundamentally from the interaction of centers having close relaxation times. Simulation showed that in this case there is an anomalous redistribution of the spectral-line intensity from the center to the wings with a virtually preserved distance between extremal points (super-Lorentzian shape of the line), which leads to underestimation of the total intensity recorded. The results obtained make it possible to explain a number of aspects of the radiospectroscopy of carbon materials of practical importance such as the nature of the generally accepted maximum on the curve for the dependence of the total intensity of an EPR signal on the temperature of the heat treatment of organic compounds and the degree of metamorphism of natural coals, the specific features of the effect of oxygen molecules and paramagnetic ions of metals on the EPR spectra of carbon materials, etc. Belarusian State University, 4, F. Skorina Ave., Minsk, 220080 Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 2, pp. 224–229, March–April, 1998.