长期低氧环境暴露对人体声光反应时间的影响

目的以单纯及多重声光选择反应时间为指标,探讨脑内信息处理过程在长期高原低氧环境下是否受到低氧干扰对反应时间的影响。方法实验组为10名在海拔4500m低氧环境暴露两年的男性战士,对照组为10名一般正常男性。受试者接受常氧(20.95%)16%、13%及10%等浓度的常压低氧处理后,进行声光选择反应时间测试。结果对照组单一选择声光反应时间及多重选择声光反应时间在低氧环境下均有增加的趋势,单一选择光反应时间,在10%氧浓度与常氧状态差异性有统计学意义(P<0.05);实验组不受低氧影响而对声光选择反应时间产生显著干扰,但经过长期高山低氧环境暴露后,反应时间与对照组已有显著性差异(P<0.05)。结论脑部光反应时间的功能,易受低氧干扰。

Photochemical Reaction of Benzoin Caged Compound： Time-Resolved Fourier Transform Infrared Spectroscopy Study

The benzoin group caged compound has received strong interests due to its excellent photo- deprotection properties and wide use in chemical and biological studies. We used timeresolved infrared spectroscopy to investigate the photochemical reaction of the benzoin caged compound, o-（2-methylbenzoyl）-DL-benzoin under 266 nm laser irradiation. Taking advantage of the specific vibrational marker bands and the IR discerning capability, we have detected and identified the uncaging product 2-methylbenzoic acid, and two intermediate radicals of benzoyl and 2-methylbenzoate benzyl in the transient infrared spectra. Our results provide spectral evidence to support the homolytic cleavage reaction of C-C=O bond in competition with the deprotection reaction. Moreover, the product yields of 2-methylbenzoic acid and benzoyl radical were observed to be affected by solvents and a largely water contalning solvent can be in favor of the deprotection reaction.

Reaction of Oncomelania Hupensis to the Allelopathic Triterpene Sapogenin from Nerium Indicum

This paper has analyzed allelopathic effects ofNerium indicum on Oncomelania hupensis through triterpene sapogenins, a potential molluscicide. The snails were treated under six various concentrations （0, 20, 40, 60, 80, 100 mg/L） of triterpene sapogenins and five periods （1, 2, 3, 4, 5 days）. The mortality of snails was positively correlated with the concentration of triterpene sapogenins and exposure time. The results ofprobit analysis showed that the LD50 （Lethal Dose, 50%） oftriterpenoid saponins from N. indicum by immersion for 2, 3, 4, 5 days were 78.31, 30.26, 20.50, 14.19 mg/L, respectively. And the corresponding 95% confidence intervals were 63.60-108.19, 9.49-44.42, 2.86-30.90, 0.23-22.79 mg/L, respectively. The observations of both scanning electron microscope and transmission electron microscope proved that 40 mg/L triterpene sapogenins could cause apparent damage to the structure of soft tissue, liver and intestine of O. hupensis. The esterase （EST） isozyme electrophoresis in liver of O. hupensis treated by 40 mg/L of the concentrations lixivium of the triterpene sapogenins from N. indicum was analyzed for 24, 48, 72, 96, 120 h, respectively. The activity of enzyme was higher than control water group after been treated up to 24-48 h, and then lowered and disappeared after 72 h. It was implicated that the extracted triterpene sapogenin from N. indicum were promising for controlling the snail, which were also providing the foundation for constructing plant community of oleander to control O. hupensis.

Silver Nanoparticles Synthesized by Laser Ablation in Acetone： Influence of Ablation Time and Their Reactivity with Oxygen in the Air

In this work, a method is proposed to control silver nanoparticle dimensions produced by laser ablation varying the ablation time and introducing a sonication phase between ablation and the successive deposition on the substrate. The absorption spectra during laser ablation show a main band, which identifies the dimensions of main particles. The appearance of secondary bands indicates the beginning of an aggregation process with the formation of a small concentration of particles which are spheroid in shape. SEM （secondary electron microscope） images of particle produced with different ablation times confirm the results of absorption measurements. X-ray photoelectron spectroscopy and cathodo-luminescence spectroscopy indicate a high reactivity of the nanoparticles deposited on a substrate. They react with oxygen in the air forming an oxide layer which reveals a luminescence in the blue region.

Study of oxidization of coal–pitch by O_3

For the purpose of obtaining small molecular and oxygen-containing aromatic compounds, taking a toluene-extracted coal pitch as the research object, the oxidation of coal-pitch by ozone （03） in formic acid was studied. The coal-pitch sample and the oxidized pitch residue were characterized by elementary analysis and Fourier transform infrared spectroscopy （FTIR）, while the small molecular products were analyzed by a gas chromatography-mass spectrometer （GC-MS）. The results show that the highest oxygen content of oxidized coal pitch had been acquired at a reaction temperature of 50℃C, an 03 flow rate of 6300 mg/h and a reaction time of 4 h. Quite a lot of hydroxyls and carbonyls were introduced into the structure of the oxidized coal-pitch, while the small molecules produced mainly involve nonpolar aro- matic compounds, aromatic anhydride and quinone compounds. It is speculated that the mechanism is direct electrophilic oxidation in which the molecules of 03 directly attack the aromatic ring at its carbon atoms with high electron density, and then generate hydroxyl or carbonyl until the aromatic ring cracks. This study shows that 03 can make the fused aromatic ring of coal-pitch become oxidized and depoly- merized, and hence the ozonization of coal-pitch can be a potential method for obtaining oxygen- containing aromatic compounds.

Removal of reactive bright-red X-3B in water by Ti/13X molecular sieves

The compound materials （shorted by Ti/13X） of doping of TiO2 into 13X molecular sieves has-been achieved by methods namely impregnation. Technical parameters of preparation for Ti/13X were determined by removal efficiency of simulation dyeing wastewater containing reactive bright-red X-3B （shorted by X-3B）. In various preparation parameters, the influence of Ti loaded on 13X molecular sieves on X-3B removal efficiency is most important. The optimum condition for volume of TiCI4 loaded on 13X molecular sieves is 8 ml at 95.9%, produced sample referred as M8. M8 was characterized using X-Ray Diffraction （XRD）, Scanning Electron Microscope （SEM）. XRD patterns of M8 revealed the incorporation of titanium into framework of 13X molecular sieves, due to the presence ofTiO2 anatase phase. SEM image showed that M8 has a large number of wormhole-like channels, in comparison with that of 13X molecular sieves. The photocatalytic tests were carried out for degradation of X-3B. The results showed that the dosage of Ti/13X, reaction time, pH, and concentration of X-3B influence the X-3B removal efficiency. The optimum conditions of photodegradation as the following： MS/X-3B ratio, Conc. is 0.3 g/l, reaction time is 120 rain, pH is 2-6. The photodegradation reaction of Ti/13X with X-3B followed first order kinetics. The rate constants and t1/2 for M8 sample at 0.3 g/l M8/ X-3B solution ratio were 430 min^-1 and 16 min, respectively.

Observation of mitochondrial activity based on temporal and spatial pH variations measured by near-field fluorescent ratiometry

A novel method combining dual wavelength fluorescent ratiometry with scanning near-field optical microscopy (SNOM) is proposed and developed to measure the concentration and distribution of protons in the vicinity of biological samples. This method involves immersing mitochondria in a pH-sensitive fluorescent dye solution instead of injecting the dye into the surface of the mitochondrial membrane. It uses a dual emission pH-sensitive dye and SNOM with a thermally pulled and metal-coated optical fiber probe to improve the spatial resolution. The time dependence of the fluorescence intensity ratio (FIR) under acid addition and the response of mitochondria to nutritional supplementation were studied by using this method. Activation of mitochondria and a distance-dependent delay in the FIR response were observed. The results confirmed that mitochondrial activity could be observed by using this method.

Use of lime mud from paper mill as a heterogeneous catalyst for transesterification

Lime mud （LM）, a solid waste from the paper mill, is used as an economic and environmental friendly heterogeneous basic catalyst for transesterification, which is accompanied by characterization of X-ray fluorescence, thermogravimetric-differential thermal analysis, X-ray diffraction, N2 adsorption, and Hammett indicator method. To investigate the performance of the achieved catalyst, which is activated through calcination, the aspects of calcination temperature, reaction time, mole ratio of methanol to oil, catalyst addition percentage, and reaction temperature are concerned. Characterization of catalyst reveals that LM could be activated through calcination to transform the carbonate and hydrate of calcium into the oxide forms and higher calcination temperature could lead to stronger basic strength. However, N2 adsorption results indicate that higher temperature causes the sintering of the catalyst and shrinkage of the catalyst grains. When LM is activated at 800℃ （LM-800） and the reac- tion is carried out at 64℃ with a methanol to oiL mole ratio of 15：1, catalyst addition percentage of 6%, and reaction time of 2 h, the maximum transesterification conversion of 94.35% could be achieved. Reusability of LM-800 is also investigated com- pared with laboratory grade CaO in five reaction cycles and the results indicate that the catalysts derived from LM can be used as an economic and efficient catalyst for biodiesel production.