Electrochemical reduction characteristics and mechanism of nitrobenzene compounds in the catalyzed Fe-Cu process

The reduction of the nitrobenzene compounds （NBCs） by the catalyzed Fe-Cu process and the relationship between the electrochemical reduction characteristics of NBCs at copper electrode and reduction rate were studied in alkaline medium（pH=11）. The catalyzed Fe-Cu process was found more effective on degradation of NBCs compared to Master Builder＇s iron. The reduction rate by the catalyzed Fe-Cu process decreased in the following order： nitrobenzene 〉4-chloro-nitrobenzene ≥m-dinitrobenzene ：〉 4-nitrophenol ≥2,4-dinitrotoluene 〉2-nitrophenol. The reduction rate by Master Builder＇s iron decreased in the following order： m-dinitrobenzene ≥4-chloro-nitrobenzene 〉4-nitrophenol 〉2,4-dinitrotoluene ≈nitrobenzene 〉2-nitrophenol. NBCs were reduced directly on the surface of copper rather than by the hydrogen produced at cathode in the catalyzed Fe-Cu process. The reduction was realized by the hydrogen produced at cathode and Fe（OH）2 in Master Builder＇s iron, It is an essential difference in reaction mechanisms between these two technologies. For this reason, the reduction by the catalyzed Fe-Cu depended greatly on NBC＇s electron withdrawing ability.     

高效垂直流人工湿地在景观湖水循环净化中的应用--以天津东丽湖景观湖水循环净化工程为例

介绍了天津东丽湖景观湖水循环净化工程的工艺流程、运行工况,并对处理效果及景观湖水质进行了分析,对人工湿地系统及景观湖泊的管理和维护进行了总结.通过近1a的运行实践表明高效垂直流人工湿地系统作为一种生态水处理技术,对微污染地表水净化具有良好的实用价值和应用前景.     

Detection of fetal cells in maternal blood

We report the detection of fetal cells in the maternal circulation by enzymatic amplification of a single copy gene sequence that was fetal-specific. Fetal HLA-A2-positive cells were sorted from maternal HLA-A2-negative cells by flow cytometry and confirmed by demonstration of a fetal-specific HLA-DR4 sequence. However, this sequence could not be detected in unenriched maternal DNA prepared at 28 and 32 weeks' gestation. The sensitivity of detection was 1 HLA-DR4-positive cell in 10⁵ HLA-DR4-negative cells. We conclude that prenatal diagnosis of paternally inherited autosomal-dominant genetic defects may be possible by selective gene amplification of maternal peripheral blood. However, preliminary enrichment for fetal cells may be necessary.     

The effect of light on the Mn(II) or Fet(lll)-catalyzed oxidation of aqueous S(IV)

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Polymerase chain reaction analysis of the cystic fibrosis ΔF508 mutation in human blastomeres following oocyte injection of a single sperm from a carrier

The efficiency of the polymerase chain reaction (PCR) in detecting the cystic fibrosis (CF) ΔF508 mutation (which is the most common mutation of CF) was assessed in single human blastomeres. Twenty-one human immature oocytes (germinal-vesicle-stage oocytes) that had been donated for research were matured in vitro and a single spermatozoon from a carrier of the CF ΔF508 mutation was injected into the ooplasm. Fourteen embryos were obtained after intracytoplasmic sperm injection (ICSI). PCR analysis was carried out on 70 single blastomeres isolated from these 14 embryos. The results showed that the efficiency of DNA amplification by PCR in single nucleate blastomeres was 94 per cent (59/63). There were no false-positive results since none of the blank samples or the blastomeres without a nucleus showed an amplified signal. We found that nine embryos were homozygous for the unaffected genotype and that four embryos were heterozygous since they contained both the unaffected and the ΔF508 genotype. In a four-cell embryo, we observed the homozygous unaffected genotype in one blastomere and a heterozygous ΔF508/unaffected genotype in the other three blastomeres.     

灭幼脲(Ⅲ)在模拟大气条件下光解行为的研究

研究了灭幼脲(Ⅲ)在模拟大气条件下的光解行为,测定了在不同气氛环境中灭幼脲(Ⅲ)的反应速率.结果表明,灭幼脲(Ⅲ)在氮气及空气中的光解为一级反应,其反应速率常数分别为:0.00703h~(-1)和0.0109h~(-1);在氧气中近似二级反应,其速率常数为0.00445h~(-1)(mg/g)~(-1).其主要光解产物为:对氯苯胺,对氯苯基异氰酸酯,邻氯苯甲酰胺,对氯苯基脲和N—(邻氯苯甲酰基)对氯苯胺.根据产物组成,建议了可能的反应历程.     

无机高分子铁钙铝混凝剂PFCA的研制及性能研究

复合型无机高分子混凝剂（ＩＰＣ）能进一步提高煤泥水的处理效果，降低有机高分子助凝剂的用量。本研究在合成得到β－ＰＦＳ溶液的基础上，引入钙铝离子共聚得到ＰＦＣＡ液体产品。含Ｆｅ＾３＋８％的ＰＦＣＡ液样通过添加晶种和活化剂的方式，极易制成偻剂产品。本文还运用透射电镜分析了ＰＦＣＡ与水中煤粒相互作用的机理。     

微生物采油技术应用及发展动态

微生物采油技术作为第四种驱油技术方法不断成熟应用也日渐广泛。介绍了微生物采油技术的特点、微生物提高原油采收率的作用机理、微生物采油技术的应用方式和技术标准。还介绍了微生物采油技术在我国的发展动态，提出了今后研究的着重点和方向。     

Calculation method of quantum efficiency to TiO2 nanocrystal photocatalysis reaction

The quantum yield is an important factor to evaluate the efficiency of photoreactor.This article vires an overall calculation method of the quantum efficiency(Φ) and the apparent quantum efficiency(Φa) to the TiO2/UV photocatalysis system.Furthermore,for the immobility system(IS),the formulation of the faction of light absorbed by the TiO2 thin film is proposed so as to calculate the quantum efficiency by using the measured value and theoretic calculated value of transmissivity(T).For the suspension system(SS),due to the difficulty to obtain the adsorption coefficient(α) of TiO2 particulates,the quantum efficiency is calculated by means of the relative photonic efficiency(ζr)and the standard quantum yield(Φstandard).     

Pathway of the ozonation of 2,4,6-trichlorophenol in aqueous solution

The reaction mechanism and pathway of the ozonation of 2,4,6-trichlorophenol (2,4,6-TCP) in aqueous solution were investigated. The removal efficiency and the variation of H₂O₂, Cl⁻ formic acid, and oxalic acid were studied during the semi-batch ozonation experiments (continuous for ozone gas supply, fixed volume of water sample). The results showed that when there was no scavenger, the removal efficiency of 0.1 mmol/L 2,4,6-TCP could reach 99% within 6 min by adding 24 mg/L ozone. The reaction of molecular ozone with 2,4,6-TCP resulted in the formation of H₂O₂. The maximal concentration of H₂O₂ detected during the ozonation could reach 22.5% of the original concentration of 2,4,6-TCP. The reaction of ozone with H₂O₂ resulted in the generation of a lot of OH• radicals. Therefore, 2,4,6-TCP was degraded to formic acid and oxalic acid by ozone and OH• radicals together. With the inhibition of OH• radicals, ozone molecule firstly degraded 2,4,6-TCP to form chlorinated quinone, which was subsequently oxidized to formic acid and oxalic acid. Two reaction pathways of the degradation of 2,4,6-TCP by ozone and O₃/OH• were proposed in this study. Translated from Acta Scientiae Circumstantiae, 2005, 25(12): 1619–1623 [译自: 环境科学学报]