Chemical Analysis Method for Carbon Bearing Refractory Products——Determination of Magnesium Oxide Content by CyDTA Volumetric Method

This standard specifies the method summary, reagents, apparatus, sampling, procedure, test results calculation and permissible tolerance of the determination of magnesium oxide by CyDTA volumetric method.

Chemical Analysis of Magnesia and Magnesia-Alumina Refractory Materials——Flame atomic absorption spectrometric method for determination of calcium oxide content

1 Scope This standard specifics the determination of calcium oxide coutent by flame atomic absorption spectrometric method.

Effect of Ligustrazine on Nitric Oxide Contents in CerebrospinalFluid and Plasma of Patients with Cerebral Infarction

Objective: To probe into the significance of Nitric Oxide (NO) in ischemic cerebral damage and effect of ligustrazine on it. Methods: The NO contents in cerebrospinal fluid (CSF) and plasma of 20 controls and 62 patients with arteriosclerotic thrombotic cerebral infarction (ligustrazine group and common treatment group) were determined with Griess method before and after treatment. Results:The NO content in CSF before treatment was higher in severe type, it was higher than that in moderate type, and than that in mild type,again higher than that in control group (all P < 0. 05) and was positively correlated with the size of infarction (P < 0. 01 ). There was no significant difference between the plasma NO content of patients and that of control group (P < 0. 05), but there was a trend that plasma NO content decreased as the patient's condition worsened. After treatment, the curative effect and plasma NO content of ligustrazine group were both markedly higher than those of common treatment group (P < 0. 05, 0. 05 ).There were no significant differences between CSF NO contents of the two groups, respectively, and that of control group (P > 0. 05,0. 05). Conclusion: Excessive NO produced in brain tissue and insufficient plasma NO participate the course of ischemic brain damage.Ligustrazine could increase the contents of plasma NO selectively.Original article on CJIM(Chin) 1998; 18(6). 342

Water Content Effect on Oxides Yield in Gas and Liquid Phase Using DBD Arrays in Mist Spray

Electric discharge in and in contact with water can accompany ultraviolet（UV）radiation and electron impact, which can generate a large number of active species such as hydroxyl radicals（OH）, oxygen radical（O）, ozone（O_3） and hydrogen peroxide（H_2O_2）. In this paper, a nonthermal plasma processing system was established by means of dielectric barrier discharge（DBD）arrays in water mist spray. The relationship between droplet size and water content was examined,and the effects of the concentrations of oxides in both treated water and gas were investigated under different water content and discharge time. The relative intensity of UV spectra from DBD in water mist was a function of water content. The concentrations of both O_3 and nitrogen dioxide（NO_2） in DBD room decreased with increasing water content. Moreover, the concentrations of H_2O_2, O_3 and nitrogen oxides（NOx） in treated water decreased with increasing water content,and all the ones enhanced after discharge. The experimental results were further analyzed by chemical reaction equations and commented by physical principles as much as possible. At last,the water containing phenol was tested in this system for the concentration from 100 mg/L to9.8 mg/L in a period of 35 min.

Effect of nitric oxide synthase inhibitor N^G-nitro-L-arginine on the content of amino acid in ischemic brain tissues of rats

BACKGROUND： Nitric oxide synthase （NOS） inhibrtors have been widely used to investigate the role of NO on cerebral ischemic injury, but the results are controversial. Moreover, it has been considered to aggravate the ischemic neuronal damage with the release of excessively excitatory amino acids （EAA） during cerebral ischemia. On the other hand, some inhibitory amino acid is suggested to be important for the neuronal protection against ischemic brain damage. Our study has recently showed that treatment with the NOS inhibitor NG-nitro-L-arginine （L-NA） reduced focal cerebral ischemic damage. The effect of L-NA on the contents of excitatory and inhibitory amino acid in the rat brain following cerebral ischemia is still unclear. OBJECTIVE： By evaluating the effect of NOS inhibitor, L-NA on the contents of aspartate, glutamate, glycine and γ-aminobutyric acid （GABA） in striatum, hippocampus and cortex in the rat brain following cerebral ischemia respectively, to investigate the beneficial effect of L-NA on cerebral ischemic injury and the possible mechanism. DESIGN： A randomized and controlled experiment SETTING ： Department of Pharmacology, Hebei Academy of Medical Sciences MATERIALS： A total of 42 male healthy SD rats （grade Ⅱ, weighting 250-300 g） were provided by the Experimental Animal Center of Hebei Province （Certification： 04036）. Aspartate, glutamate, glycine, GABA, L-NA and 2,3,5-triphenyltetrazolium chloride （TTC） were obtained from Sigma Chemicals Co, St Louis, MO, USA. HPLC-ultraviolet detector system consisted of Agilent 1100 HPLC. METHODS： The experiment was carried out in Department of Pharmrcology, Hebei Academy of Medical Sciences from June 2005 to June 2006. Rats were randomly divided into three groups： sham-operated group （n = 6）, ischemic group （n = 18）, L-NA group （n = 18）. The model of focal cerebral ischemia in rat was prepared with intraluminal line occlusion methods. In sham-operated rats, the external carotid artery was surgically prepared, but the filament was not inserted. Each group was further divided into 3 subgroups （n = 6 for each）： drugs were administrated at 2, 6 and 12 hours after the middle cerebral artery occlusion （MCAO） respectively. L-NA （20 mg/kg, ip） was administrated, twice a day, for 3 consecutive days. Same volume of normal saline was administrated in ischemic and sham operation groups. The changes of infarcted volume and the contents of amino acids were respectively assayed. Image analysis software was used for the measurement of the infarcted area. The results were expressed as a percentage of the infarcted volume of cerebral/volume of whole brain （IV%） in order to control for edema formation. The contents of aspartate, glutamate, glycine and GABA in striatum, hippocampus and cortex in the rat brain following cerebral ischemia were respectively measured by HPLC method. All data were analyzed with one-way ANOVA and Dunnett＇s test. MAIN OUTCOME MEASURES： （1） The volume of cerebral infarction; （2） The contents of aspartate, glutamate glycine and GABA in brain tissue after cerebral ischemia. RESULTS ： All 42 rats were involved in the final analysis. （1） Infarcted volume： Volume was 0 in sham-operated group. When L-NA was administrated at 2 and 6 hours after MCAO, the infarcted volume was （20.13±3.59）% and （23.12±5.84）% in L-NA group, which was not similar to that in ischemic group [（22.10±3.98）%, （25.38± 5.37）%, P〉 0.05]. However, the infarcted volume was markedly decreased compared with that of ischemic group when L-NA was administrated at 12 hours after MCAO [（26.11±3.55）% and （37.15±3.58）%, P 〈 0.01]. Changes of amino acid content： At 2 and 6 hours after ischemia, the contents of aspartate, glutamate, glycine and GABA in striatum, hippocampus and cortex in ischemic group were significantly increased compared with those in sham-operated group （ P〈 0.05-0.01）. However, contents in L-NA group were similar to those in ischemic group （P 〉 0.05）. At 12 hours after ischemia, the contents of aspartate [（0.21 ±0.06）, （0.36±0.05）, （0.29±0.12） mg/g] and glutamate [（0.55±0.06）, （0.78±0.10）, （0.52±0.10） mg/g] in striatum, hippocampus and cortex in L-NA group were significantly decreased compared with those in ischemic group [（0.49±0.17）, （0.63± 0.03）, （0.51±0.15） mg/g; （0.98±0.30）, （1.15±0.15）, （0.93±0.15） mg/g, P〈 0.05-0.01]. Glycine in hippocampus was （0.40±0.07） mg/g, which was higher than that in ischemic group [（0.21±0.07） mg/g, P 〈 0.05]. GABA in striatum, hippocampus and cortex was （0.93±0.10）, （0.62±0.12） and （0.81 ±0.10） mg/g, respectively, which was higher than that in ischemic group [（0.60±0.08）, （0.37±0.17）, （0.59±0.10） mg/g, P 〈 0.05-0.01]. CONCLUSION ： It may be concluded that L-NA have beneficial effect on ischemic cerebral injury in ischemic later stage in rats. The possible mechanism is that L-NA can decrease the contents of aspartate and glutamate, increase the contents of glycine and GABA.

New insights into the effects of silicon content on the oxidation process in silicon-containing steels

Simultaneous thermal analysis（STA） was used to investigate the effects of silicon content on the oxidation kinetics of silicon-containing steels under an atmosphere and heating procedures similar to those used in industrial reheating furnaces for the production of hot-rolled strips. Our results show that when the heating temperature was greater than the melting point of Fe2SiO4, the oxidation rates of steels with different silicon contents were the same; the total mass gain decreased with increasing silicon content, whereas it increased with increasing oxygen content. The oxidation rates for steels with different silicon contents were constant with respect to time under isothermal conditions. In addition, the starting oxidation temperature, the intense oxidation temperature, and the finishing oxidation temperature increased with increasing silicon content; the intense oxidation temperature had no correlation with the melting of Fe2SiO4. Moreover, the silicon distributed in two forms： as Fe2SiO4 at the interface between the innermost layer of oxide scale and the iron matrix, and as particles containing silicon in grains and grain boundaries in the iron matrix.

Effects of oxygen content on the oxidation process of Si-containing steel during anisothermal heating

The oxidizing behavior of Si-containing steel was investigated in an O2 and N2 binary-component gas with oxygen contents ranging between 0.5 vol% and 4.0 vol% under anisothermal-oxidation conditions. A simultaneous thermal analyzer was employed to simulate the heating process of Si-containing steel in industrial reheating furnaces. The oxidation gas mixtures were introduced from the commencement of heating. The results show that the oxidizing rate remains constant in the isothermal holding process at high temperatures; therefore, the mass change versus time presents a linear law. A linear relation also exists between the oxidizing rate and the oxygen content. Using the linear regression equation, the oxidation rate at different oxygen contents can be predicted. In addition, the relationship between the total mass gain and the oxygen content is linear; thus, the total mass gain at oxygen contents between 0.5 vol%–4.0 vol% can be determined. These results enrich the theoretical studies of the oxidation process in Si-containing steels.

Effect of Fly Ash on the Electrical Conductivity of Concretes

The fly ash occasionally has high content of iron oxide and carbon that are good electrical conducting components. This paper investigates the effect of the fly ash used as mineral admixtures on the electrical conductivity of concretes. The electrical properties of concretes using 3 kinds of fly ash with different iron oxide contents have been studied. Experimental results show that at the same fly ash dosage the resistivity of concrete using fly ash with high content of iron oxide is slightly lower than that with low content of iron oxide. However, the concrete resistivity after 14d increases as fly ash dosage increases regardless of iron oxide content in fly ash.

Comprehensive Optimization of Electrical and Optical Properties for ATO Films Prepared by Pulsed Laser Deposition

Antimony doped tin oxide（ATO） thin films have been prepared by pulsed laser deposition（PLD） method.The intrinsic effect of Sb dopant,including the Sb content,transition degree between Sb（3＋） and Sb（5＋） and crystallinity on the electrical and optical properties of the ATO thin films is mainly investigated.It is suggested that the transition degree of Sb（3＋） towards Sb（5＋）（Sb（5＋）/Sb（3＋） ratio） is determined by Sb content.When the Sb content is increased to 12 at%,the Sb（5＋）/Sb（3＋） ratio reaches the highest value of 2.05,corresponding to the resistivity of 2.70×10（-3） Ω·cm.Meanwhile,the Burstein-Moss effect caused by the increase of carrier concentration is observed and the band gap of the ATO thin films is broadened to 4.0 eV when the Sb content is increased to 12 at%,corresponding to the highest average optical transmittance of 92%.Comprehensively considering the combination of electrical and optical properties,the ATO thin films deposited with Sb content of 12 at%exhibit the best properties with the highest ＂figure of merit＂ of 3.85×10（-3） Ω（-1）.Finally,an antimony selenide（Sb_2Se_3） heterojunction solar cell prototype with the ATO thin film as the anode has been prepared,and a power conversion efficiency of 0.83%has been achieved.