2,6-二甲酚双波长分光光度法同时测定水中NO3-及NO2-的研究

水中NO₃^-和NO₂^-的一般光度法同时测定已见报导,但其操作手续均较麻烦。2,6-二甲酚光度法单独测定NO₂^-或NO₂^-虽已有报导,可是它们相互干扰。我们采用双波长光度法,测定NO₃^-和NO₂^-在H₂SO₄介质与2,6-二甲酚的反应产物,既免除了它们的相互干扰,又达到同时测定的目的。     

NiSOF／γ—Al2O3对丙烯齐聚反应的催化行为

ＮｉＳＯ４／γ－Ａｌ２Ｏ３的酸性强烈影响其催化丙烯齐聚的活性。ＣＯ中毒实验和ＥＳＲ表征证明，在反应过程中有Ｎｉ＾＋产生，并成为反应的活性中心。推测ＮｉＳＯ４／γ－Ａｌ２Ｏ３上丙烯齐聚反应除通过酸中心上酸催化进行外，还通过Ｎｉ＾＋上配位催化进行。     

Study on Generation of Glow Discharge Plasma in Air and Surface Modification of Wool Fabric

Plasma Chemistry and Plasma Processing - A lamellar electrode structure is proposed to achieve the generation of a large-area plasma and the effective processing of the wool fabric with the...     

Fabrication of novel urchin-like architecture and snowflake-like pattern CuS

The interesting biomimetic morphologenesis of CuS, containing urchin-like architecture and snowflake-like pattern can be separately obtained via heating different solutions. In our case, ethanol or the mixed solvent of ethanol/H₂O containing CuCl₂ and CS₂ as raw materials in the presence of the surfactant additive cetyltrimethylammonium bromide (CTAB) have been used. The products were characterized by various techniques of XRD, SEM and ED. In the process, the solvent medium and the surfactant additive CTAB played very important roles in the formation of different biomimetic morphologies and the formation mechanisms were primarily discussed, respectively.     

Determination of apramycin in animal feeds by solid-phase extraction and liquid chromatography with precolumn derivatization and fluorescence detection

A high-performance liquid chromatographic method for determining apramycin in animal feeds was developed. Apramycin in feeds was extracted with 0.1 M HCl solution and cleaned up with an MCX solid-phase extraction column. The purified extract was derivatized with o-phthaldehyde, and components were separated on a C18 column and detected with a fluorescence detector. Mass spectrometric data confirmed that apramycin was derivatized at all the 4 primary amines on the apramycin molecule. Average recoveries at 8 included levels (5, 10, 20, 40, 80, 200, 400, and 2000 mg/kg) ranged from 92.2 to 100.5%, and the coefficients of variation were < 6.5%. Standard curves were linear over the range 0.05 to 10 microg/mL. The detection and quantitation limits were determined to be 0.2 and 1.0 mg/kg, respectively.     

Ytterbium(II) complex bearing a diaminobis(phenolate) ligand: synthesis, structure, and one-electron-transfer and epsilon-caprolactone polymerization reactions

The first divalent ytterbium complex supported by a diaminobis(phenolate) ligand, YbL(THF)2.0.5C7H8 (1; THF = tetrahydrofuran), was synthesized in good yield by the amine elimination reaction of Yb[N(SiMe3)2]2(THF)2 with H2L (L = [Me2NCH2CH2N(CH2-2-OC6H2-3,5-But2)2]) in a 1:1 molar ratio. X-ray structural determination shows complex 1 to be a THF-solvated monomer, which adopts a distorted octahedral coordination geometry around the Yb atom. Complex 1 can react with PhNCO and PhCCH, as a single electron-transfer reagent, to give the corresponding reduction coupling product [(YbLOCNPh)(THF)]2.4THF (2) and the alkynide complex YbLCCPh(DME) (3; DME = 1,2-dimethoxyethane). Complexes 2 and 3 have been characterized by X-ray crystal structural analysis. In complex 2, the dianionic oxamide ligand resulting from the reductive coupling of two phenyl isocyanate molecules coordinates to two Yb atoms in a mu,eta4 fashion. Complex 3 has a monomeric structure with a Yb-C(terminal phenylacetynide) bond length of 2.374(3) A. Complex 1 is also a highly efficient catalyst for ring-opening polymerization of epsilon-caprolactone.     

Enhanced interface interaction between modified carbon nanotubes and magnesium matrix

Carbon nanotube (CNT)/metal interface interaction is critical to the mechanical properties of CNT-reinforced metal matrix composites (MMCs). In this paper, in order to realize the chemical modification of the interface interaction between CNTs and Mg matrix, different types of defects (monovacancy, carbon and oxygen adatoms, as well as p-type boron and n-type nitrogen substitution) are introduced in CNTs to investigate the effect of the defects on the interface interaction (E_ib) between CNT and Mg (0 0 0 1) surface. Moreover, two models (adsorption model and interface model) are compared and validated to investigate the interface interaction. It is revealed that the CNT with the carbon adatom has the highest E_ib with the Mg (0 0 0 1), and the effect of boron doping on E_ib is superior to the intermediate oxygen which has already been proved experimentally in the enhancement of the interface interaction in MMCs. In terms of the electronic structure analysis, we reveal the micro-mechanism of the increase of E_ib under the action of different types of defects, and propose that the presence of holes (boron dopant) and the unsaturated electrons in CNTs can generate the chemical interaction between CNT and Mg matrix effectively. Our results are of great scientific importance to the realization of robust interfacial bonding between CNTs and Mg matrix via the reinforcement modification, so as to enhance the mechanical properties of CNTs reinforced Mg matrix composites.     

Ab initio exploration of d<Superscript>0</Superscript> digital magnetic heterostructures: the case of MgO and CaO <Emphasis Type="Italic">δ</Emphasis>-doped with potassium

Previous studies of digital magnetic heterostructures have mainly focused on 3d transition metal δ-doped semiconductors. In this work, sp-electron digital magnetic heterostructures without magnetic ions are proposed. Based on a theoretical density functional investigation, electronic structures and magnetic properties of MgO and CaO δ-doped with K were reported. The results show that these heterostructures are half-metallic ferromagnetic materials having semiconducting up spins and metallic down spins, with an exchange interaction much stronger than that of a random alloy with similar K concentration. Our first-principles calculations show that the carriers at the Fermi level are strongly confined within a few monolayers around the KO plane. This strong confinement is responsible for the large exchange coupling and the two-dimensional half-metallic behavior. The thickness of the host semiconducting spacer does not significantly change the global electric and magnetic features.     

具有服务等级的两台同型机实时在线排序

考虑具有服务等级的两台同型机在线排序问题, 其中工件带有到达时间, 目标为最小化最大完工时间, 设计了竞争比为\frac{7}{4}的在线算法.