First-principles theory for the H + H2O, D2O reactions

A full quantum dynamical study of the reactions of a hydrogen atom with water, on an accurate ab initio potential energy surface, is reported. The theoretical results are compared with available experimental data for the exchange and abstraction reactions in H + D2O and H + H2O. Clear agreement between theory and experiment is revealed for available thermal rate coefficients and the effects of vibrational excitation of the reactants. The excellent agreement between experiment and theory on integral cross sections for the exchange reaction is unprecedented beyond atom-diatom reactions. However, the experimental cross sections for abstraction are larger than the theoretical values by more than a factor of 10. Further experiments are required to resolve this.     

2A80铝合金材料热疲劳寿命研究

介绍了能量准则及其计算方法，并对用2A80铝合金材料制成的带有不同环状缺口的试件进行了热疲劳和高温低周疲劳试验与应力应变分析计算，试件试验和计算分析的结果表明，总应能能密度-ΔWt是疲劳寿命预测的有效参量，且不受试件结构形状和尺寸的影响。     

超声/紫外/O3/H2O2处理去除水中DDT的研究

[目的]研究超声/紫外/O3/H2O2处理去除水中DDT的效果,为建立新的去除水中DDTs的AOPs技术提供参考。[方法]配制一定浓度的DDT水溶液,分别采用超声、紫外、O3/H2O2、超声/紫外和超声/紫外/O3/H2O2组合处理,并用超声/紫外/O3/H2O2组合处理北江佛山段水样,用GC-EDC方法检测DDT含量变化,比较各处理方法的DDT去除率。[结果]水中DDT去除率分别为:超声波处理为45%～56%、紫外光处理近70%、超声/紫外联合处理超过80%、O3/H2 O2处理为28%～32%、超声/紫外/O3/H2 O2处理为91%,而北江水样DDT去除率达到85%。[结论]超声/紫外/O3/H2O2联合处理可有效去除水中DDT。     

双氧水处理对甜菜种子发芽的影响

双氧水浸种处理叶甜菜和根甜菜种子 ,可明显提高种子的发芽率、发芽势及发芽指数。叶甜菜以浓度 2 %～ 5%的双氧水处理为宜 ,根甜菜以浓度 3%的双氧水处理为宜 ;对贮期较长的种子则以浓度 5%的双氧水处理为佳。叶甜菜和根甜菜均不宜贮藏较长时间     

过氧化氢光催化脱色甲基橙溶液的研究

本文在H2O2存在下用紫外灯照射对甲基橙溶液进行光催化脱色。结果表明,甲基橙溶液的脱色率随着H2O2的增加而增加,但存在一个最佳值。当甲基橙浓度低于25 mg/L时,反应为假一级,当甲基橙浓度高于100 mg/L时,反应为零级;但是不符合Langmuir-Hinshewood动力学模型。脱色率在酸性条件下比碱性条件高。日光照射下对实际染料废水的脱色效果好。     

Antarctic Ozone Depletion Chemistry: Reactions of N2O5 with H2O and HCl on Ice Surfaces

The reactions of dinitrogen pentoxide (N(2)O(5)) with H(2)O and hydrochloric acid (HCl) were studied on ice surfaces in a Knudsen cell flow reactor. The N(2)O(5) reacted on ice at 185 K to form condensed-phase nitric acid (HNO(3)). This reaction may provide a sink for odd nitrogen (NO(x)) during the polar winter, a requirement in nearly all models of Antarctic ozone depletion. A lower limit to the sticking coefficient, gamma, for N(2)O(5) on ice is 1 x 10(-3). Moreover, N(2)O(5) reacted on HCl-ice surfaces at 185 K, with gamma greater than 3 x 10(-3). This reaction, which produced gaseous nitryl chloride (ClNO(2)) and condensed-phase HNO(3), proceeded until all of the HCl within the ice was depleted. The ClNO(2), which did not react or condense on ice at 185 K, can be readily photolyzed in the Antarctic spring to form atomic chlorine for catalytic ozone destruction cycles. The other photolysis product, gaseous nitrogen dioxide (NO(2)), may be important in the partitioning of NO(x) between gaseous and condensed phases in the Antarctic winter.     

荔枝裂解色谱指纹图谱及聚类分析

采用裂解色谱法测定,运用模糊聚类法分析比较不同品种荔枝的指纹图谱.研究结果表明,裂解温度、裂解时间分别选择450℃、30 s较为合适,21种荔枝样品的指纹图谱具有相似性,重现性好.该方法具有快速、简便、准确等特点,可为进一步开展荔枝的品质鉴定提供依据.     

重金属污染土壤H2O2预处理的植物修复技术研究

采用反应平衡法并结合盆栽试验研究了H2O2对重金属污染土壤的活化作用及对后续植物修复中重金属根际效应的影响.研究表明污染土壤施入H2O2后,水溶性总铜、总锌均较对照有显著的增加,说明H2O2对污染土壤重金属的活化有很强的效果.Fe2+加入使重金属活性降低,施加量越高,土壤溶液水溶性铜锌含量越低.经H2O2预处理的土壤栽种黑麦草后将进一步溶出铜锌,其中,对黑麦草根际水溶态铜含量的影响比锌显著.H2O2预处理并不改变污染土壤重金属的主要存在形态,但经H2O2预处理的土壤栽种黑麦草后,水溶态+交换态铜含量增幅较大说明经H2O2预处理重金属在土壤中的结合强度可能减弱,易于受根际的影响而活化.H2O2预处理土壤栽种黑麦草后,弱专性吸附态铜锌均明显增加、残渣态铜锌减少.即提取试验和盆栽试验结果均表明H2O2预处理对提高土壤中重金属的生物有效性、促进植株吸收重金属效果显著.     

制备γ-Fe2O3纳米微粒的一种新方法

提出了两次反应制备γ-Fe2O3纳米微粒的新方法.制备过程中通过控制第2次反应中NaOH的浓度实现了由结晶的FeOOH逐渐转化为结晶的γ-Fe2O3纳米微粒.用X射线衍射仪(XRD)、透射电子显微镜(TEM)和振动样品磁强计(VSM)分别对纳米微粒的晶体结构、形态和大小、磁化强度进行表征.实验结果表明,γ-Fe2O3纳米微粒具有高结晶性,形状近似为球形,饱和磁化强度达63.90 A·m2/kg,是γ-Fe2O3块体饱和磁化强度的84.1%.     

自形成MnFe2O4磁性液体的制备和磁性

用化学共沉淀法制备MnFe2O4纳米微粒,并且采用自形成法制备了粒子型磁性液体.在这种磁性液体中,通过适当的酸蚀,Mn2+和Fe3+离子从MnFe2O4纳米微粒溶解并吸附在磁性微粒表面以阻止微粒团聚.微粒和磁性液体都呈磁滞回线.这种磁化性质可能来源于在高场下产生的不可逆团聚.

Abstract：

MnFe2O4 nanoparticles are prepared by chemical coprecipitation method. Based on the MnFe2O4 nanoparticles, a self-formed ionic ferrofluid is synthesized. In the ferrofluid, Mn2+ and Fe3+ ions dissolved from the MnFe2O4 nanoparticles via suitable acid attack are adsorbed on the surface of the magnetic particles, thus preventing the particles from aggregating. The average thickness of ionized layers of the ferrofluid particles is about 1 to 2 nm.Both the particles and the ferrofluids have hysteresis behavior. The behavior may result from irreversible aggregation induced under high magnetic field.     

钯修饰电极的制备及其对H_2O_2的电催化还原作用研究

[目的]研究钯化学修饰电极在H2O2检测中的应用。[方法]采用循环伏安法制备了钯修饰的复合陶瓷碳电极(Pd/CCE),研究了该修饰电极对H2O2的电催化性能。[结果]在含有PdCl2.2H2O的H2SO4溶液中(pH 1.2),控制扫描电位范围为0～1.0 V(vs.SCE)连续扫描40圈时制得的Pd/CCE修饰电极对H2O2具有较强的电催化活性,安培法检测H2O2的线性范围为6.0×10-5～1.0×10-2mol/L,检出限为2.2×10-5mol/L(3Sb)。[结论]直接电沉积得到的钯修饰电极,可实现较低电位下测定H2O2,且电极具有制作简单、价格低廉、响应时间短和表面容易更新等特点。     

微波辅助H_2O_2-CH_3COOH氧化脱除柴油中的硫

使用微波辅助H2O2-CH3COOH试剂氧化0#柴油脱硫,在反应温度为70℃,复合氧化剂冰乙酸(CH3COOH)和H2O2体积比为1∶1,微波频率为2 450 MHz时,通过改变微波功率、剂油体积比和反应时间确定柴油中硫的最佳脱除效果。结果显示,在微波功率为380 W,剂油体积比为8∶1,反应7 min时,柴油中硫的脱除率达88.5%。     

BiFeO3磁性纳米粒子催化H2O2降解甲基橙的研究

通过溶胶-凝胶法成功合成了铁酸铋磁性纳米粒子(BiFeO3 MNPs),X-射线衍射结果表明,得到的BiFeO3具有高度结晶和单相钙钛矿结构.将其用于催化过氧化氢降解偶氮染料甲基橙(MO)的研究,探讨了各因素对去除率的影响;结果表明,在不调pH值的情况下,当BiFeO3 MNPs质量浓度为1.0 g/L、过氧化氢浓度为0.2 mol/L、温度为30℃、反应时间为24 h时,对MO的去除率可达到90％.     

Limits for combustion in low O2 redefine paleoatmospheric predictions for the Mesozoic

Several studies have attempted to determine the lower limit of atmospheric oxygen under which combustion can occur; however, none have been conducted within a fully controlled and realistic atmospheric environment. We performed experimental burns (using pine wood, moss, matches, paper, and a candle) at 20 degrees C in O2 concentrations ranging from 9 to 21% and at ambient and high CO2 (2000 parts per million) in a controlled environment room, which was equipped with a thermal imaging system and full atmospheric, temperature, and humidity control. Our data reveal that the lower O2 limit for combustion should be increased from 12 to 15%. These results, coupled with a record of Mesozoic paleowildfires, are incompatible with the prediction of prolonged intervals of low atmospheric O2 levels (10 to 12%) in the Mesozoic.     

Evidence for Photochemical Formation of H2O2 and Oxidation of SO2 in Authentic Fog Water

When samples of rain and fog water were exposed to ultraviolet and visible light, reactive transients such as hydrogen peroxide were formed and dissolved organic matter and sulfur dioxide were depleted. These results, in conjunction with those from previous studies, imply that dissolved organic compounds and transition metals such as iron ions are involved in the photochemical formation of hydrogen peroxide and other photooxidants in atmospheric waters.