Spectrum characteristics and pump wavelengths of Nd3+-doped double-clad fiber

Conclusion The optimum wavelength of Nd³⁺-doped double-clad fiber laser or amplifier made in China is near 830 nm. The efficiency of Nd³⁺-doped double-clad fiber devices pumped by 820-nm laser is low due to ESA. In order to increase the photochemical stability of the outer cladding, the material of the outer cladding must be advanced.     

Effect of various stressors on the levels of lipid peroxide,antioxidants and Na+, K+-ATPase actrivity in rat brain

The level of malondialdehyde (MDA), an index of lipid peroxidation, and the antioxidants superoxide dismutase (SOD) and glutathione (GSH), as well as the activity of Na⁺, K⁺-ATPase, were assessed in whole rat brain after immobilization, anemic hypoxia (NaNO₂) and 72 h starvation. The effect of these stressors on plasma glucose and corticosterone levels was also observed. Hypoxia and starvation stimulated the lipidj peroxide formation in braini as indicated by an increase in the level of MDA, being higher after starvation than hypoxia. Brain SOD activity was also increased in response to hypoxia and starvation while GSH content was only diminished ini hypoxia. However, neither MDA nor antioxidants were affected by immobilization. On the other hand, the activity of brain Na⁺, K⁺-ATPase was significantly increased by immobilization and hypoxia but decreased in starvation. A similar pattern of change was also observed in plasma glucose and corticosterone levels in response to these stressors. These results elucidate differences in the biochemical response of animals towards various types of stress, with increased lipid peroxide formation in hypoxia and starvation.     

Antioxidant survey to assess antagonism to redox stress using a prokaryotic and an eukaryotic system

Using a prokaryote (Escherichia coli) and a metazoa-resembling eukaryote (Ochromonas danica), we surveyed antioxidants which might overcome redox stress imposed by menadione sodium bisulphite (MD) and buthionine sulphoximine (BSO). BSO oxidant stress was evident only inO. danica; MD oxidant stress was evident in both organisms. Glutathione, its precursors, e.g. cysteine, homocysteine, and 2-oxo-4-thiazolidine carboxylic acid, and red blood cells, emerged as prime antioxidants for relieving BSO and MD oxidant stress. BSO and MD oxidant activity and antioxidant-annulling effect inO. danica were judged comparable to those found in animal cells whereas the resultsE. coli were not entirely equivalent. TheO. danica system emerged as a practical, rapid, and useful system for pinpointing oxidant stressors and antioxidants, and shows promise for studies with mammalian systems.     

(−)-Epigallocatechin gallate,a polyphenolic tea antioxidant,inhibits peroxynitritemediated formation of 8-oxodeoxyguanosine and 3-nitrotyrosine

Reaction with peroxynitrite at pH 7.4 and 37°C was found to increase the 8-oxodeoxyguanosine levels in calf thymus DNA 35-38-fold. This oxidation of deoxyguanosine, as well as the peroxynitrite-mediated nitration of tyrosine to 3-nitrotyrosine, was significantly inhibited by ascorbic acid, glutathione and (–)-epigallocatechin gallate, a polyphenolic antioxidant present in tea. For 50% inhibition of the oxidation of deoxyguanosine to 8-oxodeoxyguanosine, 1.1, 7.6 of 0.25 mM ascorbate, glutathione or (–)-epigallocatechin gallate, respectively, was required. For 50% inhibition of tyrosine nitration, the respective concentrations were 1.4, 4.6 or 0.11 mM. Thus, (–)-epigallocatechin gallate is a significantly better inhibitor of both reactions than either ascorbate or glutathione. Reaction of (–)-epigallocatechin gallate with peroxynitrite alone resulted in the formation of a number of products. Ultraviolet spectra of two of these suggest that the tea polyphenol and/or its oxidation products are nitrated by peroxynitrite.     

关于微分方程组dU／dt=H·U的李代数解

求解线性微分方程组6UN，llH（z）．U（t），U（0）ll1的方法，已经由JamesWei和EdwardNorman给出(1)，他们的方法建立在李代数理论的基础之上。本文讨论解的结构。对于上述方程组，其中U是有限维空间中依赖于时间的线性算子，而H（＝6t（Ht、（z）＋．．．．．．、，！（r），！＋（z），如果Ht，Hz，…，，！。生成可解的李代数L，则它的解U（U＝explgt（r）HJexpk2（…”exp“（z）1可以表示为一个矩阵，其所有的元素都是g（illl，2，…，m）的初等函数，并且只出现指数函数与乘幂。最后用两个例子说明具体的解法。     

蕴涵环交换性的某些多项恒等式

设ｍ＞１，ｎ，ｐ，ｑ，ｒ，ｓ均为正整数，Ｒ是一个具有单位元１的环．证明了：如果Ｒ中的任意ｘ，ｙ满足且Ｒ具有Ｑ（ｍ）性质，则Ｒ是一个交换环．此外，在适当的条件下确立了Ｒ的交换性．     

Growth ages of ferromanganese crusts from the western and central Pacific： Comparison between nannofossil analysis and ^10Be dating

Based on results of nannofossil analysis and 10Be dating in ferromanganese crusts M1-1 and A1-1 (no nannofossils were found in it),from the western and central Pacific respectively,it is found that the crust growth ages from nannofossil biostrati-graphy agree well with those based on 10Be isotope analysis. Both crusts have three growth layers,and the oldest layer was deposited in Miocene at about 12.80 Ma. The maximum,minimum,and average growth rates of crust A1-1 (from the central Pacific) are 8.11,1.92 and 3.47 mm/Ma,and those of crust M1-1 (from the western Pacific) are 2.93,0.47,and 0.94 mm/Ma.     

Growth of Magnetite Nanoparticles under Magnetic Fields

1 Introduction Over the past several years, the preparation and characterization ofnanoscale magnetic materials, especially one-dimensional (1D) nanostructure, have attracted much attention as the nanomaterials would allow investigating the fundamental aspects of magnetic-ordering phenomena in magnetic materials with reduced dimensions and could lead to new potential applications such as data storage technology[1-6].