Studies of plasma dynamics in megampere X-pinches

Results are presented from experimental studies of the dynamics and parameters of the plasma generated by megampere (up to 2.3 MA) currents flowing through X-pinches formed from crossed wires made of various materials. The experiments were performed with different numbers of wires and different wire diameters. The X-ray yield in neon-like molybdenum lines (in the 2.5- to 3-keV photon energy range) from a <20 μm hot spot was larger than 10 J, and the soft X-ray power emitted from this spot reached 120 GW. The hot-spot lifetime estimated by comparing the measured and calculated emission intensities and line profiles of helium-like Fe and Cr ions was ～10 ps. Hard X-ray emission in the photon energy range ≥800 keV was also detected.     

Oleic acid Enhances Dengue Virus But Not Dengue Virus-Like Particle Production from Mammalian Cells

Despite the recent introduction of a commercial vaccine, the mosquito-transmitted dengue virus is still a worldwide public health problem. Based on the live attenuated vaccine strategy, the commercial vaccine has a less than optimal protective profile. Virus-like particles (VLPs) offer an attractive alternate vaccination strategy due to the effectively native presentation of epitopes in the absence of any infectious genetic material. However, the production of amounts of VLP in a platform that can support commercial development remains a major obstacle. This study generated two DENV 2 VLPs [codon-optimized and chimeric DENV/Japanese encephalitis virus (JEV)] and directly compared yields of these constructs by western blotting and dot blot hybridization. The effect of oleic acid supplementation, a process known to increase DENV production in natural infection, was also investigated. Results showed that the chimeric construct gave a two- to threefold higher yield than the codon-optimized construct and that while oleic acid increased DENV virion production in natural infection, it inhibited VLP production. These results suggest that further optimization of DENV VLP expression is possible, but it will require more understanding of how native DENV infection remodels the host cell machinery.     

pH dependency of kinetic parameters and reaction mechanism of beef liver catalase.

The pH-dependence of the kinetic parameters in H2O2 decomposition by beef liver catalase was investigated. At pH 7.0, the ternary complex (ESS) decomposition rate was about 100 times faster than ESS formation (42 microM H2O2), and the value of the Michaelis constant was 0.025 M. From ethanol competition experiments, two different proton dissociation constants of the enzyme (pKe1 = 5.0, pKes2 = 5.9) were obtained for the binding of first and second H2O2 molecules. Another pKa value (pKes1) of 4.2 was obtained from the pH dependence of overall rate constant (ko). The reaction mechanism of catalase was discussed in relation to these ionizable groups.     

Effect of cold adaptation of α-and β-adrenergic responses of blood pressure in hindlimb and small intestine in situ and systemic blood pressure in rabbits

Changes in the main parameters of α-and β-adrenergic responses, sensitivity to agonists (EC ₅₀) and maximum response (P _m) of hindlimb and small intestinal blood pressure in situ and systemic blood pressure were studied in rabbits adapted to cold for 1–30 days (daily exposures to ?10°C for 6 h). The responses to phenylephrine, noradrenaline, adrenaline, clonidine (α-agonists), and isopropylnoradrenaline (β-agonist) corresponded to the equation p = (P _m A ⁿ )/(EC ₅₀ ⁿ + A ⁿ ) (1) with n = 1 and n = 2, respectively. Cold adaptation induced reciprocal changes in the response of both EC ₅₀ and P _m to α-agonists and in the response of P _m alone to isopropylnoradrenaline. The significant differences of the parameters from control observed during the first 5 days of adaptation gradually decreased by day 30. After 10 days of adaptation, the efficiency (E = P _m/2EC ₅₀) of response to α-and β-agonists of adrenoceptors significantly increased.     

Characterization of polyhydroxyalkanoates (PHAs) biosynthesis by isolated Novosphingobium sp. THA_AIK7 using crude glycerol

Biodiesel-contaminated wastewater was used to screen for PHAs-producing bacteria by using crude glycerol as the sole carbon source. A gram-negative THA_AIK7 isolate was chosen as a potential PHAs producer. The 16S rRNA phylogeny indicated that THA_AIK7 isolate is a member of Novosphingobium genus which is supported by a bootstrap percentage of 100% with Novosphingobium capsulatum. The 1,487 bp of 16S rRNA gene sequence of THA_AIK7 isolate has been deposited in the GenBank database under the accession number HM031593. Polymer content of 45% cell dry weight was achieved in 72 h with maximum product yield coefficient of 0.29 g PHAs g?1 glycerol. Transmission electron micrograph results exhibited the PHAs granules accumulated inside the bacterial cell. PHAs polymer production in mineral salt media supplemented with 2% (w/v) of crude glycerol at initial pH 7 was extracted by the sodium hypochlorite method. Polymer film spectrographs from Nuclear magnetic resonance displayed a pattern of signal virtually identical to spectra of commercial PHB. Thermal analysis by Differential scanning calorimeter showed a melting temperature at 179°C. Molecular weight analysis by Gel permeation chromatography showed two main peaks of 133,000 and 700 g mol?1 with weight-average molecular weight value of 23,800 and number-average molecular weight value of 755. Endotoxinfree of PHAs polymer was preliminarily assessed by a negative result of the gel-clot formation, Pyrotell? Single test vial, at sensitivity of 0.25 EU ml?1. To our knowledge, this is the first reported test of endotoxin-free PHAs naturally produced from gram-negative bacteria which could be used for biomedical application.     

云南松SSR-PCR反应体系的建立与优化

为了建立适宜云南松SSR-PCR的反应体系和扩增程序,利用近缘种火炬松的引物,采用正交设计L16(45)对云南松SSR-PCR反应体系的5因素(Taq酶、Mg2+、模板DNA、dNTP、引物)在4个水平上进行优化,筛选出各反应因素的最佳水平,建立了适于云南松的SSR反应体系.在10μL的反应体系中,模板DNA的用量为30.0 ng,Taq DNA聚合酶的用量为1.0 U,Mg2+的浓度为2.0 mmol/L,dNTPs浓度为0.4 mmol/L,引物的浓度为0.2 μmol/L.扩增程序为:94℃预变性4 min;94℃变性45 s,48℃退火30 s,72℃延伸30 s,30个循环;72℃延长10 min,4℃保存.最后利用1个居群对该体系进行稳定性验证,结果可用于云南松SSR标记的研究.     

X-pinch-based neutron source

Results are presented from experimental studies of the parameters of an X-pinch-based neutron source made of 70- to 80-μm-diameter deuterated polyethylene fibers. At currents of up to 1.7 MA and a current rise time of ～150 ns, hot plasma spots were observed in the fiber crossing region. The formation of hot spots was accompanied by the generation of short soft X-ray pulses with a duration of 2–4 ns, as well as by neutron emission. The neutron energy was measured using the time-of-flight technique in four directions, at 0°, 90°, 180°, and 270° with respect to the load axis. The mean energy of the neutrons emitted along the axis towards the anode and cathode was found to be 2.0 ± 0.2 and 2.6 ± 0.1 MeV, respectively, and that of neutrons emitted in two opposite directions along the radius, 2.5 ± 0.1 and 2.4 ± 0.1 MeV. The maximum neutron yield at a current amplitude of 1.6 MA was of 10¹⁰ neutrons per shot.