c轴定向氮化铝薄膜的制备

利用电子回旋共振 (ECR)微波增强化学气相沉积法 (PECVD)并使用氮气 (N2 ) ,氩气 (Ar)和AlCl3蒸气作为气源在直径为 6 .35cm的 (10 0 )单晶硅片表面制备了c轴定向氮化铝 (AlN)薄膜 ,并使用X射线衍射仪及其X射线特征能谱和扫描电镜 (SEM)分析了薄膜特征 ,研究了微波功率、基板温度和N2 流量对薄膜c轴定向的影响 ,得到了c轴偏差角小于 5°的高质量大面积AlN薄膜。     

Determination of iphosphamide and seven metabolites in blood plasma,as stable trifluoroacetyl derivatives,by electron capture chemical ionization GC-MS

A method is described for the determination of the antitumor agent iphosphamide and seven of its metabolites in the plasma of cancer patients by multiple ion monitoring (MIM) GC-MS, mainly using the electron capture chemical ionization mode, of stable methyl and/or trifluoroacetyl derivatives. The metabolites determined were 2- and 3-dechloroethyliphosphamide, 4-ketoiphosphamide, carboxyiphosphamide, iphosphamide mustard, and two previously undetected metabolites, chloroethylamine and 1,3-oxazolidine-2-one. The isolation of the acidic and neutral metabolites was performed by solid phase extraction on to C₁₈ adsorbent at pH 4. The weakly acidic iphosphamide mustard, isolated under these conditions with a yield of ca 50%, was measured as a stable methyltrifluoroacetyl derivative, in contrast to the corresponding phosphoramide mustard of the isomer cyclophosphamide which decomposes during derivatization. Chloroethylamine and 1,3-oxazolidine-2-one were isolated with high yield by liquid extraction with ethyl acetate at pH 10. Selective measurement of several metabolite derivatives with similar retention times was performed by multiple ion monitoring MS of specific ion masses, using a methyl phenyl siloxane capillary column previously employed in the study of cyclophosphamide metabolites. Quantitation of metabolites in patient plasma samples could be performed in the concentration range 3 ng to 20 μg per ml of original plasma.     

奇异类内离差矩阵条件下的Fisher最优判据

特征提取是模式分类与识别的重要环节，Fisher最优判据是特征提取的基本方法之一．本文提出了一种计算奇异类内离差矩阵条件下Fisher最优判据的新方法，并给出了计算步骤．     

鲤鱼体中鱼腥味物质的提取和鉴定

采用同时蒸馏萃取法提取鲤鱼鱼体中的挥发和半挥发性有机物，用GC／MS从提取物中分析鉴定出鱼腥味和疑是鱼腥味物质16种。包括醛、烯醛、酮和呋喃4类化合物。其中己醛、庚醛和2，4-二烯癸醛被确认为鱼腥味的化合物。研究发现，这些物质总量在鲤鱼体的鱼鳞、鱼鳃和鱼肉的分布呈现下降趋势，且其总量与鱼腥味强度之间具有可比较的对应关系。     

The Fundamental Experiments of Red Tide Chemical Forecast

Many food algae and red tide algae were cultivated in the f/2 medium, and the nitric oxide (NO) concentration of the medium and the cell density were determined. The experiments on algae were conducted when different concentrations of NO were added into the medium using two methods. The results show that low concentrations of NO were self-produced by marine algae during the exponential growth period and were about nmol/L level. But at the end of the period, i.e., 2 or 3 days before the cell density reaches the maximum, an NO peak appeared, with the NO concentration reaching 10 nmol/L. The NO threshold concentration exists according to the influence of exogenous NO on the marine phytoplankton growth. One type is the threshold concentration that can promote algae growth, and its value is between 10 and 1 nmol level, or even lower. The other type can inhibit the phytoplankton growth, which is about μmol level or higher. The results indicate that red tide algae are far more sensitive to NO than are food algae. The fundamental experimental outcome above may provide a new clue for red tide chemical forecast by inspecting the NO change.     

Ion chromatography–inductively coupled plasma mass spectrometry determination of arsenic species in marine samples

Arsenic speciation analysis in marine samples was performed using ion chromatography (IC) with inductively coupled plasma mass spectrometry (ICP‐MS) detection. The separation of eight arsenic species, viz. arsenite, monomethyl arsonic acid, dimethylarsinic acid, arsenate, arsenobetaine, tetramethylarsine oxide, arsenocholine and tetramethylarsonium ion was achieved on a Dionex AS4A (weaker anion exchange column) by using a nitric acid pH gradient eluent (pH 3.3 to 1.3). The entire separation was accomplished in 12 min. The detection limits for the eight arsenic species by IC–ICP‐MS were in the range 0.03–1.6 µ g l^?1, based on 3σ of the blank response (n = 6). The repeatability and day‐to‐day reproducibility were calculated to be less than 10% (residual standard deviation) for all eight species. The method was validated by analyzing a certified reference material (DORM‐2, dogfish muscle) and then successfully applied to several marine samples, e.g. oyster, fish muscle, shrimp and marine algae. The low power microwave digestion was employed for the extraction of arsenic from seafood products. Copyright © 2004 John Wiley & Sons, Ltd.     

HCHO-(DL-苹果酸)-BrO-3-Mn2+-H2SO4体系化学振荡反应动力学研究

研究了HCHO参与下的(DL-苹果酸)-BrO-3-Mn2+-H2SO4化学振荡反应体系的非线性动力学行为,考察了该体系中各反应物的初始浓度范围及主要影响因素. 结果表明,在5.0×10-5～1.0×10-2 mol·L-1范围内, HCHO对振荡反应的诱导期和周期有较大影响,且HCHO浓度的对数lnc(HCHO)与诱导期倒数的对数ln(1/tin)及周期倒数的对数ln(1/tp)均存在线性关系. 诱导期和周期的表观活化参数分别为70.87,55.71 kJ·mol-1. 另外还对HCHO参与下的可能振荡反应机理进行了探讨.     

Geometry and electronic structure of a heterometallic cluster Mo<Subscript>2</Subscript>Mg<Subscript>2</Subscript> in different oxidation states of Mo: a DFT study

Reduction of tetranuclear heterometallic complex Mo₂Mg₂ was simulated using the B3LYP and PBE density functional methods. The results of geometry calculations of the initial complex [Mo^VIO₂Mg(MeOH)₂(OMe)₄]₂ and a partially reduced Mo^V complex are in good agreement with experimental data. The reduced Mo^III complex is characterized by a decrease in the binding energy of aqua ligands. Structural rearrangement of the complex with release of a coordination position at the Mo atoms requires small energy expenditure. One can assume that the reduction of the polynuclear complex causes overcrowding of its coordination sphere, which favors formation of dinitrogen complexes. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 441–457, March, 2008.     

On the Donor Ability of the Phosphaneiminato Substituent and Cube Formation with Transition Metal Fragments

The particular role of the phosphaneiminato ligand as a donor is investigated for a) nitrenes (phosphinidenes) and carbenes and b) cubane formation with transition metals. Accordingly, and as shown for the case a) the ligand is a stronger π‐donor than an amino group and can be considered as a special case of imine‐type substituents. The latter are very effective in π‐donation. In the case b), i.e. the cubane formation with transition metals, one has to consider transition metals with a partially or completely filled d‐shell (with electrons). Hence depending on the transition metal, cubanes are build with weak ferromagnetic coupled or closed shell systems. For the cubanes with closed shell character the matter of insertion of halide anions is discussed. In the last chapter of the review the bond stretching in the dithionitrosyl complexes with rhenium is characterized.     

卤代对苝醌类光敏剂光敏活性影响的量子化学研究

以一种新型的醌类光敏剂—菌生素 (HMB)为模型化合物 ,利用量子化学从头算HF/ 6 31G和含时密度泛函TD B3LYP/ 6 31G方法计算研究了卤代作用对醌类光敏剂分子性质和光敏活性的影响 .结果发现 ,卤代作用降低了HMB母体的HOMO和LUMO能级 (EHOMO和ELUMO)及其差值△E ,随卤族元素从上到下 ,EHOMO和ELUMO呈增大趋势 ,而△E呈减小趋势 ,使得分子激发光谱有不同程度的红移 ,在增加PQP三重态量子产率的同时降低了分子最低三重激发态的能量 ,两种作用相互抵消 ,使得卤代物的 1O2 量子产率与母体相似 ;增加了分子的绝热电子亲合势 ,使分子产生O2 -的能力下降 ;卤原子的引入 ,降低了HMB母体分子内氢键的强度 ,同时使顺式构型的分子内质子传递势垒增大 ,而使反式构型势垒减小 .