一氧化氮与休克

本文就近年来对NO的研究及其与休克关系的报道作简要叙述。一、NO的生物学特性 1.化学特性:NO有很强的亲脂性,极易透过生物膜,与血红蛋白、肌球蛋白和可溶性鸟苷酸环化酶上的铁离子有高度亲合性;其可激活鸟苷酸环化酶,生成环-磷酸鸟苷(cGMP),cGMP介导血管平滑肌的舒张,调节局部血流。 2.生物合成:NO由NO合酶(NOS)氧化L-精氨酸(L-Arg)的胍基氮而产生。NOS主要有两种,一类是先天就存在的结构型NOS(cNOS),其活性依赖于NADPH、Ca^(2+)及钙调素的存在。另一类是细胞受到脂多糖(LPS)。

An Improved Water-filled Pulse Tube Method Using Time Domain Pulse Separation Method

Based on existing low-frequency water-filled impedance tube testing facilities, which is a part of the Low Frequency Facility of the Naval Undersea Warfare Center in Beijing, an improved water-filled pulse tube method is presented in this short paper. This proposed study is significantly different from the conventional pulse tube method because of the capability for a single plane damped sine pulse wave to generate in the water-filled pulse tube with a regular waveform and short duration time of about 1ms. During the generation process of the pulse, an inverse filter principle was adopted to compensate the transducer response. The effect of the characteristics of tube termination can be eliminated through the generation process of the pulse. Reflection coefficient from a water/air interface was measured to verify the proposed method. When compared with the expected theoretical values, a relatively good agreement can be obtained in the low frequency range of 500-2 000 Hz.

Heat and Radiation Generation during Hydrogenation of CH Compound

Securing new sources of energy has become a major concern, because fossil fuels are expected to be depleted within several decades. In some of the major wars of the 20th century, control of oil was either a proximate cause or a decisive factor in the outcome. Especially in Japan and Germany, a great deal of research was devoted to making liquid fuels from coal. In one such experiment, a large amount of excess heat was observed. The present study was devoted to replicating and controlling that excess heat effect. The reactant is phenanthrene, a heavy oil fraction, which is subjected to high pressure and high heat in the presence of a metal catalyst. This results in the production of excess heat and strong penetrating electromagnetic radiation. After the reaction, an analysis of residual gas reveals a variety of hydrocarbons, but it seems unlikely that these products can explain the excess heat. Most of them form endothermically, and furthermore heat production reached 60 W. Overall heat production exceeded any conceivable chemical reaction by two orders of magnitude.

Runner Bean （Phaseolus coccineus L.） Production in Chile

Runner bean is usually grown in Chile as household plantings, in small surfaces with trellis support. Several studies were made to grow runner beans extensively without trellis support, like common beans are grown. Three runner bean ecotypes were evaluated, with and without trellis support. Although the highest yield was obtained with trellis support, significant yields were obtained without trellis. Thus, this specie can be established without support like the common bean, allowing a great economic advantage especially at large scale plantings. The ecotype named ＂Quilapallar＂ was selected by its white and large grains and excellent cooking quality. Then, seed rates and dry grain yield were compared with commercial varieties of common bean. There was not statistical difference in yield among row distances, except when this was 25 cm apart. Besides, there was not statistical difference among Quilapallar and Torcaza INIA, although the later is a common bean variety with a high yield potential.

Neutral responses of plant community Ca concentration to nitrogen enrichment in a semiarid grassland

Calcium(Ca)is an essential nutrient for plant growth and Ca concentrations in forage have important implications for ruminant diet and health.It remains an open question whether forage Ca concentration would be decreased by increasing nitrogen(N)deposition.We manipulated the increasing rates of N addition(2008–2015)in a semiarid grassland,northern China.Plant Ca concentrations for all species were examined in each plot under N treatment.The Ca concentrations at functional group and community levels were calculated based on the concentration of each species presented and their relative biomass in each plot.We found that community-level Ca concentration remained stable across a gradient of wide-ranged N addition rates,although Ca concentration at both species and functional group levels showed negative responses to N enrichment.Given that forbs had higher Ca concentration than grasses,the increasing relative biomass of forbs canceled out the negative responses of species-level and functional group-level Ca concentration.Our results further showed that community Ca pool showed a positive but saturating response to N addition,with a threshold at the rate of 10 g N m^(−2)yr^(−1).Our findings highlight the role of changes in plant relative biomass in controlling the responses of forage Ca concentration and stock to N enrichment.

Microbial D-amino acids and marine carbon storage

In nature, there are two conformational types of amino acids: L- and D-isomers. The L-amino acids are the predominant form and are used mainly for protein synthesis, while the D-amino acids are few in quantity but more diverse in terms of their biological functions. D-amino acids are produced by many marine microbes, which are important players in carbon and energy cycles in the ocean. As the major constituent of the marine organic carbon pool, D-amino acids can persist in the water column for a long time before being further transformed by chemical or biological processes or transported through physical processes(such as absorption and aggregation). This article reviews the microbial synthesis of D-amino acids, their physiological function and metabolism in microbes, and the contribution of D-amino acids as a carbon source to the oceanic carbon reservoir.