Determination of some basic constants of sec-octylphenoxy acetic acid

In this work some basic constants of extractant Sec-Octylphenoxy acetic acid (CA-12) such as solubility (S) in water, dissociation constant (K-a) in aqueous solution, dimerization constant( K-2) and distribution constant (K-d) between water and haptane have been determined by two phase titration method. The results are as follows: S = 1.40 x 10(-4) mol/L, K-a = 3.02 x 10(-4), K-2 = 3.56 x 10(2), K-d = 4.06 x 10(2) (25 +/-0.5 degreesC).

In-situ circular dichroism spectroelectrochemical study on the redox process of norepinephrine

The redox process of norepinephrine in pH = 7.0 phosphate buffer solution at glassy carbon electrode was studied by circular dichroism spectroelectrochemistry with a long optical path thin layer cell. The spectroelectrochemical data were analyzed with the double logarithm method. According to the double logarithsmic plot results, the mechanism of electrochemical oxidation of norepinephrine is an irreversible process with a subsequent chemical reaction (EC) to form a norepinephrinechrome. Both of norepinephrinequinone and norepinephrinechrome are followed E mechanisms. Some kinetic parameters about the electrochemical process, i.e. the electron transfer coefficient and number of electron transfered, alpha n = 0.38, the formal potential, E-1(0)' = 0.20 V, the standard heterogenous electron transfer rate constant, k(1)(0) = 1.2 x 10(-4) cm s(-1) for the oxidation of norepinephrine, alpha n = 0.37, E-2(0)' = 0.25 V and k(2)(0) = 4.4 x 10(-5) cm . s(-1) for the reduction of norepinephrinequnone and alpha n = 0.33, E-3(0)' = -0.25V and k(3)(0) = 1.1 x 10(-4) cm . s(-1) for the reduction of norpinephrinechrome, were also estimated.

In situ UV-vis and CD thin-layer spectroelectrochemistry study of the electrochemical behavior of L-noradrenaline in alkaline solution

Electrochemical redox behavior of noradrenaline in alkaline solution on a glassy carbon electrode has been investigated by in situ UV-vis and CD spectroelectrochemistry by using a long optical path thin-layer cell. The experimental data were processed by using a double logarithmic method of analysis together with nonlinear regression which confirmed that the first step in both the oxidation of noradrenaline and reduction of noradrenochrome is a two-electron irreversible process governed by an EE mechanism. The kinetic parameters of the electrode reactions, i.e., charge transfer coefficient and the number of electrons transferred, alpha(1)n(1) = 0.11 and alpha(2)n(2) = 0.23, formal potentials modified with kinetics, E-1(0') = 0.65 (+/- 0.01) V and E-2(0') = 0.72V and standard rate cnstants, k(1)(0) = 7.0(+/-0.5)x10(-5) cm s(-1), for the first and second steps in the oxidation process of noradrenaline, and similarly, alpha(1)n(1) = 0.33, alpha(2)n(2) = 0.58, E-1(0') = 0.37(+/-0.01) V, E-0' = -0.25 (+/-0.01) V and k(1)(0) approximate to k(2)(0) = 1.06 (+/-0.05)x10(-4) cm s(-1) for the first and second steps in the reduction process of noradrenochrome were also determined.

SYNTHESIS AND STRUCTURE OF (ETA-5-C5H5)2YB.DME

(eta-5-C5H5)2YbCl.THF reacts with an equivalent molecular quantity of K(2,4-C7H11) (2,4-dimethyl pentadienyl potassium), and treatment of the product with DME yields (eta-5-C5H5)2Yb.DME. The crystal of (eta-5-C5H5)2Yb.DME belongs to the orthorhombic space group Fdd2 with a = 13.678(4) angstrom, b = 23.255(6) angstrom, c = 9.192(2) angstrom and Z = 8. The crystal parameters are found to differ from previously reported data.

新型无机高分子混凝剂聚硅酸铝铁的应用及动态模拟实验研究

目前在废水处理领域，其处理方法有生物化学法、离子交换法、化学氧化法、电渗析法和混凝沉淀法等，而应用最普遍、并且成本较低的处理方法仍然是混凝沉淀法。它几乎可以用于各种工业废水和城市污水的预处理、中间处理和最终处理，以及污泥处理当中。混凝剂性能是影响混凝沉淀处理效果的关键因素。因此，研制和开发高效能、低毒无公害、低能耗、低成本的新型混凝剂就显得非常重要。我们自行研制成功的聚硅酸铝铁类系列混凝剂(PSAFC、PSAFS、PSAFCS)，作为新型的无机高分子复合型混凝剂，属于水溶性无机高分子物质。其实质为铝、铁盐类水解过程的中间产物与硅酸根阴离子等基团的结合体。本文在前人工作的基础上，主要研究了复合型聚硅酸铝铁类混凝剂(PSAFCS)的配制、各类不同配比混凝剂的粘度、ζ电位与混凝效果的关系、以及对印染废水、垃圾渗滤液和造纸废水的静态和动态混凝处理效果等，得到了以下相应的认识和结论。1．在聚硅酸铝铁类混凝剂配制阶段，由于SiO_2的引入将影响混凝剂的聚合度、Zeta电位、存放时间和混凝处理效果等，本论文测定出水玻璃模数K，其值为2.86。而且，硅的存在使混凝剂形态发生了改变，吸附架桥能力增强，增加了混凝剂聚合度，但在某种程度上降低了混凝剂的电中和能力。2．考虑到铝和铁在聚合反应中速度的差异，铁具有极强的亲OH~-能力，能极快地与OH~-形成多羟基聚合物；而铝的亲OH~-能力相对较弱，聚合反应速度缓慢。为了能够使铝盐与铁盐交叉共聚，在配制混凝剂时需采取先加含铝原料，稳定后再加含铁原料的方式。碱化度B是在制备混凝剂时的一个重要操作指标，寻求最佳的碱化度值有利于制备出高效的混凝剂。3. 在PSAFCS中，硫酸根的引入在某种程度上可以增加混凝剂的聚合度和稳定性，增强絮凝能力。并且不同SO_4~(2-)/CI~-比的混凝剂在混凝效果上存在差异。另外，目前市场上工业硫酸与工业盐酸价格相差不大，而工业硫酸的当量数是工业盐酸的1.94倍，故用硫酸代替部分盐酸可降低酸耗成本。4．Ferron逐时络合比色法被广泛应用于铝盐、铁盐溶液的形态分析，并且可得出较好的分析结果。但是在铝铁共存的溶液中进行形态分析，尚有一定困难。5．混凝剂的表观分子量与粘度之间存在着正比关系，通过测定，聚硅酸铝铁类混凝剂的增比粘度随着存放时间有一定的上升趋势，其中硫酸盐型混凝剂(PSAFS)的趋势最明显，存放时间相对较短。盐酸盐型混凝剂(PSAFC)的增比粘度与PSAFS和PSAFCS相比最小。说明其聚合度最小，硫酸根的介入可使聚硅酸铝铁类混凝剂的聚合度增大。比浓粘度与质量浓度之间存在着一定的正相关关系。6. 混凝剂的ζ电位值由于硅的引入而变得有正有负，这与不同类型混凝剂中硅、铝、铁的相对含量有关。一般SiO_2:(Al+Fe)比值大于1:2时，ζ电位为负值。7．系统阐述了PSAFC和PSAFS在印染废水处理中的应用，经过混凝处理的印染废水出水中，残留硅的含量在0.16mg／L～1.68mg／L之间；残留铁的含量在22.4 μg／L～0.52mg／L之间；残留铝的含量在0.1lmg／L～2.60mg／L之间，而且残留铝含量与碱化度B值之间有着很好的负相关关系，即随着混凝剂碱化度值的增大，残留铝含量降低。系列聚硅酸铝铁类混凝剂对印染废水的色度、浊度、COD等都有较好的去除效果。8．第一次把聚硅酸铝铁类混凝剂应用于垃圾填埋场渗滤液的处理上，通过混凝一臭氧氧化处理后，垃圾渗滤液的BOD_去除率达75.4％、COD去除率达70．6％、色度去除率达94％，其出水水质基本接近我国生活垃圾填埋场污染控制标准(GBl6889--1997)二级标准。9．首次在实验室内进行动态模拟实验，我们用自行设计的动态处理装置，选用13号PSAFCS型混凝剂对造纸废水进行试验，混凝剂SiO_2:Al:Fe比值为1:0.75:0.75，ζ电位为10.8毫伏。在最佳水力条件和最佳混凝剂投量的情况下，对造纸废水的COD去除率达92.5％、色度去除率达96.9％，达到国家造纸工业污染物排放一级标准，说明复合型聚硅酸铝铁类混凝剂(PSAFCS)对造纸废水有着优异的去除效果。

Kinetics of the selective reduction of NO with CH4 over an In-Fe2O3/HZSM-5 catalyst

A kinetic model presented for the selective reduction of NO with CH4 over an InFe2O3/HZSM-5 catalyst by considering the process as a combination of two simultaneous reactions: NO+O2CH4 (reaction 1) and O-2+CH4 (reaction 2). Linear regression calculation was employed to find the kinetic parameters. It was found that although the activation energies of the two reactions were almost identical, the reaction rate constants were dramatically different, namely, k(1)much greater than k(2), indicating that the NO+O-2+CH4 reaction was more preferable to take place on the In-Fe2O3/HZSM-5 catalyst as compared with the O-2+CH4 reaction.

4.2度K下注NGaAlAs光荧光研究

Submitted by zhangdi (zhangdi@red.semi.ac.cn) on 2009-04-13T11:45:31Z

光纤位移传感器在77和4.2 K下的输出特性研究

介绍了一种可用于低温装置内的补偿式光纤位移传感器(CFODS),讨论了该传感器在低温下的输出特性并在液氮温度(77 K)和液氦温度(4.2 K)下进行了实验研究.结果表明,该传感器在液氮温度下的灵敏度0.311 mm~(-1),高于液氦温度下的灵敏度0.278 mm~(-1).

Photoemission evidence for dilute k-doped phase KxC（60） with x<0.2

于2010-11-23批量导入

Gadolinium heteropoly complex K-17[Gd(P2W17O61)(2)] as a potential MRI contrast agent

Gadolinium heteropoly complex K-17[Gd(P2W17O61)(2)] has been evaluated by in vitro and in vivo experiments as a potential contrast agent for magnetic resonance imaging (MRI). The thermal analysis and conductivity study indicate that this complex has good thermal stability and wide pH stability range. The T-1 relaxivity is 7.59 mM(-1) s(-1) in aqueous solution and 7.97 mM(-1) s(-1) in 0.725 mmol l(-1) bovine serum albumin (BSA) solution at 25degreesC and 9.39 T, respectively. MR imaging of three male Sprague-Dawley rats showed remarkable enhancement in rat liver after intravenous injection, which persisted longer than with Gd-DTPA. The signal intensity increased by 57.1 +/- 16.9% during the whole imaging period at 0.082 mmol kg(-1) dose. Our preliminary in vitro and in vivo studies indicate that K-17[Gd(P2W17O61)(2)] is a potential liver-specific MRI contrast agent.

Single-crystal X-ray structure and properties of K-10[Ni-4(H2O)(2)(AsW9O34)(2)]center dot 4H(2)O

The rational synthesis and the structural and magnetic characterization of a nickel cluster are presented. The compound comprises a rhomblike Ni4O16 group encapsulated between two-heptadentate tungstoarsenate ligands [AsW9O34](9-). The crystal structure of K-10[Ni-4(H2O)(2)(AsW9O34)(2)](.)4H(2)O was solved in monoclinic, P2(1)/n symmetry, with a = 12.258(3) Angstrom, b = 21.232(4) Angstrom, c = 15.837(3) Angstrom, beta = 92.05(3)degrees, V = 4119.1(14) Angstrom(3), Z = 2, and R = 0.0862. The crystal structure of the Ni(II) derivative was compared with that of the Cu(II), Zn(II), Co(II) and Mn(II) derivatives. The Ni4O14(H2O)(2) unit in the compound shows no Jahn-Teller distortion. On the other hand, the Ni(II) derivative shows ferromagnetic exchange interactions within the Ni4O16 group (J = 7.8 cm(-1), J' = 13.7 cm(-1)) and an S = 4 ground state, the highest spin state reported in a heteropoly complex. Its redox electrochemistry has been studied in acid buffer solutions using cyclic voltammetry. It exhibited two steps of one-electron redox waves attributed to redox processes of the tungsten-oxo framework. The new catalyst showed an electrocatalytic effect on the reduction of NO2-.

ABF_3:Eu,Gd(A:K,Li;B:Ba,Mg)中Gd~(3+)→Eu~(2+)的能量传递

通过高温固相反应法,在高纯N_2气氛中合成了BaLiF_3,KMgF_3中单掺和双掺Eu,Gd的ABF_3型复合氟化物。研究了各类掺杂体系的光谱特性,观察到了Gd~(3+)→Eu~(2+)的能量传递,分析了能量传递过程,探讨了能量传递机理,并讨论了Gd~(3+)和Eu~(2+)的取代格位。

Synthesis and crystal structure of a novel amino-acid-containing polyoxometalate: K-6[Cu (Ala)(2) (H2O)(2)](2)[ CU4 (H2O)(2) (AsW9O34)(2)] center dot 16H(2)O

The novel amino-acid-containing polyoxometalate Ka(6) [Cu(Ala)(2) (H2O)(2)](2) [Cu-4 (H2O)(2) . (AsW9O34)(2)] . 16H(2)O was synthesized from the reaction of K-10[Cu-4(H2O)(2)(AsW9O34)(2)] . 20H(2)O with beta -alanine, Its structure has been determined by single crystal X-ray diffraction. It crystallizes in the triclinic space group P (1) over bar, with a=1. 196 3(2) nm, b=1. 536 5(3) nm, c=1. 591 4(3) nm, alpha =93. 97(3)degrees, beta= 110. 88(3)degrees, gamma =101. 07(3)degrees, V=2. 651 8(9) nm(3) and Z=1. Least-squares refinement of the structure leads to R and R-w factors of 0. 067 3 and 0. 162 8, respectively. An unusual structural feature of the compound is that the polyanion [Cu-4(H2O)(2) (AsW9O34)](10-) is linked with the amino-acid complex of Cu2+ by a mu -oxygen atom.

The origin of nonlinearities in K[B5O6(OH)(4)]center dot 2H(2)O crystal

In this paper the origin of nonlinearities of the K[B5O6(OH)(4)].2H(2)O(KB5) crystal has been investigated from a comprehensive view-point by using the bond-valence theory of complex crystals. The results of the calculation (d(31) = -1.18 X 10(-10) esu, d(32) = 0.20 X 10(-10) and d(33) = -1.03 X 10(-9) esu) are in good agreement with experimental data. For the first time we pointed out that its nonlinearities come from the H(2)-O(2) bonds and the [B5O6(OH)(4)](-) group, and estimated its larger nonlinear optical (NLO) coefficient d(33).