Characteristics and Temperature Measurement of a Non-Transferred Cascaded DC Plasma Torch

Dependence of the current-voltage characteristics of a non-transferred DC cascaded plasma torch used for nanoparticle synthesis, on the plasma current and the plasma argon gas flow rate are reported in this paper. The potential structure inside the torch and its dependence on the plasma current and gas flow rate are also investigated. The arc voltage is seen to exhibit negative characteristic for a current below 150 A and positive characteristic above that current value. The voltage drop near the electrodes is found to decrease with the increase in plasma current. 25~ of the total voltage is dropped near the cathode at a plasma current of 50 A and a argon plasma gas flow rate of 10 liter per minute （LPM）, and it decreases to 12% with the current increasing to 300 A, and to 17% with a gas flow rate of 25 LPM. The variation in the torch efficiency with the gas flow rate and plasma current is also reported. The efficiency of the torch is found to be between 36% and 48%. In addition, the plasma gas temperature at various positions of the reactor and for different currents and voltages are measured by calorimetric estimation with a heat balance technique.

Distribution of CD 4^+ Lym phocyte Th1/Th2 Subsets in Peripheral Blood of Women with Idiopathic Prem ature Ovarian Failure

Thepathogenesisof prem ature ovarian failure (POF) rem ains unknow n. Accu- m ulated evidences indicate that abnorm ality in the im m une system m ay be one of the m ajor reasonsand theim balanceof Thelp typeI(Th1) and Thelp typeII(Th2) m ay play an importantrolein theprocess. Study of thedistribution and functionalstatusof Th1/Th2 m ay behelpfulforevaluating thepathogenesisof POF.13 patientsw ith id- iopathic POFand 7 w om en of reproductiveagew ith norm alcyclew ereenrolled in this study.The percentage of Th1 and Th2 cellsfrom peripheralblood of thepatientsand the controls w as studied using FITC labelled CD4 m Ab to separate CD4+ cells by FACS, in com bination w ith in situ hybridization using Dig-labelled IL2, IL6 cDNA probes.Results:The patients w ith POF had significantly higher percentage of Th1 cellsascompared w ith the controls(49.76±9.22,20.06±7.10respectively, P< 0.001).The ratio of Th1/Th2 in thepatientsw ith POFw assignificantly higherthan thatof thecontrols(1.15±0.17, 0.63±0.09, P< 0.001). Conclusions: Thefindings of thisstudy suggestthatpatientsw ith POFhaveincreased Th1 cellactivation, w hich m ay be related to the pathogenesisof POF. Corresponding author: WANG Yi-li E-m ail: w yl@ irix. xam u. edu. cn

Akkermansia muciniphila: a promising target for the therapy of metabolic syndrome and related diseases

The probiotic Akkermansia muciniphila(A. muciniphila) is an intestinal bacterium that was first identified in human feces in 2004. Its specialization in mucin degradation makes it a key microorganism that maintains intestinal mucosal barrier function. As an unique representative strain of the phylum Verrucomicrobia that can be cultured in vitro, A. muciniphila is much easier to detect by metagenomic analysis of intestinal flora. In the past few years, A. muciniphila has been getting increasing attention for the positive correlation between its intestinal colonization and host homeostatic metabolism. In this review, we summarize the relationship between A. muciniphila and host health and diseases, especially focusing on metabolic diseases and related mechanisms, as well as the natural food and drug-derived substrates affecting its colonization in the host, expecting to provide evidence and clues for the development of drugs targeting A. muciniphila.

CHARACTERIZATION OF γ-RADIATION CROSSLINKED CRYSTALLINE POLYMERS BY CRYSTALLIZATION TEMPERATURE

The effect of gamma-radlatlon on plain crystalline polymers and crystalline polymers containing different amounts of difunctional monomer both in vacuum and in air at room temperature has been investigated with DSC. It was found that the crystallization temperature T_c of crosslinked sample measured on DSC at a constant cooling rate decreases with increasing radiation dose. The difference between T_c before and after crosslinking (T_(c_0)-T_(c_R)) is linearly related to the radiation dose for plain polymer. Based on the Charlesby-Pinner equation, an expression has been derived:where S is the sol fraction, A and B are constants. Since there is evidence that T_c is relative to S or crosslinking desity only and independent of the radiation crosslinking, the equation is also applicable to the enhanced gamma-radiation crosslinking of the polymer and can be used to evaluate the instantaneous G(c.1.)_R value of nonrandom crosslinking system. Therefore, determination of T_c with DSC offers a convenient approach to the quantitative study of the random and especially nonrandom crosslinking reaction of crystalline polymer.

Predictions of high-pressure structural, electronic and thermodynamic properties of α-Si_3N_4

The plane-wave pseudo-potential method within the framework of first-principles technique is used to investigate the fundamental structural properties of Si3N4. The calculated ground-state parameters agree quite well with the experimental data. Our calculation reveals that α-Si3N4 can retain its stability to at least 45 GPa when compressed below 300 K. No phase transition can be seen in the pressure range of 0-45 GPa and the temperature range of 0-300 K. Actually, the α→β transition occurs at 1600 K and 7.98 GPa. Many thermodynamic properties, such as bulk modulus, heat capacity, thermal expansion, Gr/ineisen parameter and Debye temperature of a-Si3N4 were determined at various temperatures and pressures. Significant differ- ences in these properties were observed at high temperature and high pressure. The calculated results are in good agreement with the available experimental data and previous theoretical values. Therefore, our results may provide useful information for theoretical and experimental investigations of the N-based hard materials like α-Si3N4.