Electrode characteristics and microstructure of AB(2)-AB(5) composite hydrogen storage alloy formed by ball-milling process

For improving the electrode characteristics of the Zr-based AB(2)-type alloy, a new kind of composite hydrogen Zr0.9Ti0.1(Ni0.50Mn0.35V0.15)(2)(represented as AB(2)) with a rare storage alloy was successfully prepared by ball-milling I earth-based AB(5)-type alloy (represented as AB(5)) which worked as a surface modifier. Effects of ball-milling on the electrode characteristics and microstructure of Zr0.9Ti0.1(Ni0.50Mn0.35V0.15)(2) alloy and mixtures of AB(2) with AB(5) alloy were investigated. After milling the mixed AB(2) and AB(5) powders (9: 1 in mass ratio) for 10min, XRD and SEM analysis showed that AB(2) and AB(5) maintained their original crystalline states, respectively, some AB(5) particles were adhered onto the surface of AB(2), and some fresh surfaces were formed. It was found that the activation cycles of AB(2)-AB(5) composite alloy was shortened from 14 to 7 and the maximum discharge capacity was increased from 330mAh . g(-1) to 347mAh . g(-1) as compared with AB(2) alloy. The discharge rate capability of AB(2) alloy was also improved by ball milling AB(2) with AB(5) alloy process. The combined effect of ball-milling and mixing with AB(5) alloy is superior to that of sole treatment. It was believed that AB(5) alloy works not only as a regular hydrogen storage alloy, but also as a surface modifier to catalyze the hydriding/ dehydriding process of AB(2) alloy.

Synergistic extraction of zinc(II) with mixtures of CA-100 and cyanex 272

The extraction of zinc(II) from an aqueous chloride medium has been studied using mixtures of sec-nonylphenoxy acetic acid (CA-100) and bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272). The results demonstrate that zinc ion is extracted into heptane as ZnA(2).2HA with CA-100, ZnL2.2HL with Cyanex 272, and ZnA(2)L(2)H(2) with synergistic mixture. The equilibrium constants of the these species have been calculated and extraction mechanisms have been proposed. Thermodynamic parameters of the extraction process were determined by the temperature coefficient of extractability. The synergistic system enhances the extraction efficiency of zinc(II) and also improves the selectivity between zinc(II) and cadmium(II).

Electrochemiluminescence of dichlorotris (1,10-phenanthroline) ruthenium (II) with peroxydisulfate in purely aqueous solution at carbon paste electrode

The electrochemiluminescence (ECL) of dichlorotris (1,10-phenanthroline) ruthenium (11) [Ru(phen)(3)(2+)] with peroxydisulfate (S2O82-) was first described. The use of carbon paste electrodes, organic solvent modified electrodes, allowed obtaining ECL in purely aqueous solution. The ECL produced by the reaction of electrogenerated C Ru(phen)(3)(2+) with the strongly oxidizing intermediate SO4-., was observed only when the applied potential was negative enough to reduce Ru(phen)(3)(2+). In comparison with Ru(bpy)(3)(2+)/S2O82- ECL, the Ru(phen)(3)(2+)/O-8(2-)/S2O82- ECL was more stable in aqueous solution. It was not affected by the storage of the carbon paste electrodes, and it quenched only at quite high S2O82- concentrations. The ECL intensity was a function of S2O82- concentration, increasing linearly with the S2O82- concentration from 5 X 10(-6) to 2 X 10(-3) mol l(-1), and dropping off sharply at S2O82- concentration higher than 20 mmol l(-1). The proposed ECL method with Ru(phen)(3)(2+) was sensitive and selective for the determination of S2O82-. (C) 2002 Elsevier Science B.V. All rights reserved.

Liquid crystalline and light emitting polyacetylenes: Synthesis and properties of biphenyl-containing poly(1-alkynes) with different functional bridges and spacer lengths

Biphenyl- (Biph-) containing 1-alkynes (3 and 4) and their polymers (1 and 2) with varying bridge groups and spacer lengths were synthesized and the effects of the structural variation on their properties, especially their mesomorphism and photoluminescence behaviors, were studied. The acetylene monomers 3(3) [HCdropC(CH2)(3)O-Biph-OCO(CH2)(10)CH3] and 4(m) [HCdropC(CH2)(m)OCO-Biph-OCO(CH2)(10)-CH3, m = 3, 4] were prepared by sequential etherization and esterification reactions of 1-alkynes. While 3(3) exhibits enantiotropic crystal E and SmB mesophases, its structural cousin 4(3) displays only a monotropic SmB phase. Enantiotropic SmA and SmB mesophases are, however, developed when the spacer length is increased to 4. Polymerizations of the monomers are effected by Mo-, W-, Rh-, and Fe-based catalysts, with the WCl6-Ph4Sn catalyst giving the best results (isolation yield up to 85% and M-w up to 59000). The polymers were characterized by IR, UV, NMR, TGA, DSC, POM, XRD, and PL analyses. Compared to 1(3), 2(3) shows a red-shifted absorption, a higher T-i, and a better packed interdigitated bilayer SmA(d) structure, while the mesophase of 2(4) involves monolayer-packing arrangements of the mesogens. Upon photoexcitation, 1(3) emits almost no light but 2(m) gives a strong ultraviolet emission (lambda(max) similar to 350 nm), whose intensity increases with the spacer length.

Fluorescence analysis of phospholipase A(2) isolated from Chinese agkistrodon blomhoffii Ussurensis venom

The general and synchronous spectra of phospholipase A(2) (PLA(2)) isolated from Chinese agkistrodon blomhoffii Ussurensis snake venom were studied. The chromophores of PLA(2) were mainly contributed by tyrosine and tryptophane residues when the intervals between the excitation wavelength and the emssion waveleagth (Delta lambda) were 20nm and 75nm, respectively. The pH of buffers could change the fluorescence intensities of PLA(2) by changing the charge distribution of its amino acid chain. Ca2+ can not only increase the emission fluorescence intensity of PLA(2) but also improve the reaction rate of PLA(2) with its corresponding substrate DPPC.

The NMR-spectroscopic and X-ray crystal-structural characterization of two Cp*Ir halfsandwich complexes containing the 1,2-dicarba-closo-dodecaborane-1,2-diselenolato ligand

The reaction of [Cp*IrCl2](2) with dilithium 1,2-orthocarborane-1,2-diselenolate 3 leads to the green 16-electron diselenolene complex [Cp*Ir{Se2C2(B10H10)}] (4) which takes up two-electron ligands such as trimethylphosphane to give the 18-electron diselenolate derivative [Cp*Ir(PMe3)-{Se2C2(B10H10)}] (5). The molecular structures of 4 and 5 were determined by X-ray crystal structure analysis. The Se-77-nuclear shielding in 4 is lower by almost 500 ppm relative to that in 5.

The use of half-sandwich iridium dithiolate and diselenolate complexes, Cp*Ir(L)(ER)(2) (L = CO, PMe3, PPh3; ER = SPh, SePh, SeMe), for the synthesis of heterodimetallic compounds. The molecular structure of Cp*Ir(CO)(mu-SePh)(2)[Mo(CO)(4)]

Carbonyl-iridium half-sandwich compounds, Cp*Ir(CO)(EPh)(2) (E = S, Se), were prepared by the photo-induced reaction of Cp*Ir(CO)(2) with the diphenyl dichalcogenides, E2Ph2, and used as neutral chelating ligands in carbonylmetal complexes such as Cp*Ir(CO)(mu-EPh)(2)[Cr(CO)(4)], Cp*Ir(CO)(mu-EPh)(2)[Mo(CO)(4)] and Cp*Ir(CO)(mu-EPh)(2)[Fe(CO)(3)], respectively. A trimethylphosphane - iridium analogue, Cp*Ir(PMe3)(mu-SeMe)(2)[Cr(CO)(4)], was also obtained. The new heterodimetallic complexes were characterized by IR and NMR spectroscopy, and the molecular geometry of Cp*Ir(CO)(mu-SePh)(2)[Mo(CO)(4)] has been determined by a single crystal X-ray structure analysis. According to the long Ir...Mo distance (395.3(1) Angstrom), direct metal-metal interactions appear to be absent. (C) 1998 Elsevier Science S.A. All rights reserved.

Synthesis, crystal structure and magnetic properties of a series of polymeric lanthanoid-copper complexes [Ln(2)Cu(3){O(CH2-CO2)(2)}(6)].nH(2)O (Ln=La, Nd, n=9; Ln=Er, n=6)

The reaction of diglycolic acid, O(CH2CO2H)(2), with Cu(NO3)(2) . H2O and lanthanoid nitrate hydrate produces a series of novel Ln-Cu mixed metal complexes, [Ln(2)CU(3){O(CH2CO2)(2)}(6)]. nH(2)O (Ln = La, Nd, n = 9; Ln = Er, n = 6), which have been characterized by elemental analysis, i.r. spectroscopy, magnetic measurements and X-ray crystallography. The Ln(3+) and Cu2+ ions are connected by the carboxylate groups of the ligands, resulting in the formation of a complicated network.

Synthesis and chemical properties of [Z]-1-[2-(triaryl stannyl)vinyl]cyclooctanol

The compounds of [Z]-1-[2-(triphenyl stannyl) vinyl] cyclooctanol (1) and [Z]-1-[2-(tri-p-tolyl stannyl) vinyl] cyclooctanol (2) were synthesized by the reactions of triphenyltin hydride and tri-p-tolyltin hydride with 1-ethynyl cyclooctanol. The crystal structure of compound 1 was determined. The reactions of compound 1 and 2 with IC1, Br-2, I-2 formed nine organotin halides. The organotin oxide or hydroxide were prepared by the reactions of [Z]-1-[2-(phenyl dibromo stannyl) vinyl] cyclooctanol (6) and [Z]-1-[2-(diphenyl monobromo stannyl) vinyl] cyclooctanol (5) with KOH. Three complexes were obtained by the reactions of [Z]-1-[2-(phenyl diiodide stannyl) vinyl] cyclooctanol (8) with three ligands (2,2'-bipyridyl,5-nitro-1,10-phenanthroline,8-Hydroxyquinoline). The sixteen new compounds synthesized in this paper were characterized by means of elemental analysis, IR, H-1 NMR. The reaction mechanism of triphenyltin hydride and tri-p-tolyltin hydride with 1-ethynyl cyclooctanol were also proposed.

SYNTHESIS, CHARACTERIZATION AND CATALYTIC BEHAVIOR OF LA2-XSRXCOO4+/-LAMBDA (X=0-2) IN COMPLETE OXIDATION

A series of mixed oxides La2-xSrxCoO4+/-lambda (x=0-2) with varying x values was synthesized. The crystal structure of this series of mixed oxides was studied by using XRD. The result showed that when x=0.25-1.5 the mixed oxides possessing K2NiF4 structure are formed. The valences of the transition metal Co and the relation between +/-lambda content and x value by using chemical analysis method have been measured, too. The redox property of this series of mixed oxides and different kinds of oxygen species were studied by IR, TPD, TPR, XPS and SEM methods. The catalytic activity in the complete oxidation of CO and CH4 was investigated and the relationships between the activity, composition and structure of the mixed oxides have been elucidated.

Enrichment of the hydrogen-producing microbial community from marine intertidal sludge by different pretreatment methods

To determine the effects of pretreatment on hydrogen production and the hydrogen-producing microbial community, we treated the sludge from the intertidal zone of a bathing beach in Tianjin with four different pretreatment methods, including acid treatment, heat-shock, base treatment as well as freezing and thawing. The results showed that acid pretreatment significantly promoted the hydrogen production by sludge and provided the highest efficiency of hydrogen production among the four methods. The efficiency of the hydrogen production of the acid-pretreated sludge was 0.86 +/- 0.07 mol H-2/mol glucose (mean +/- S.E.), whereas that of the sludge treated with heat-shock, freezing and thawing, base method and control was 0.41 +/- 0.03 mol H-2/mol glucose, 0.17 +/- 0.01 mol H-2/mol glucose, 0.11 +/- 0.01 mol H-2/mol glucose and 0.20 +/- 0.04 mol H-2/mol glucose, respectively. The result of denaturing gradient gel electrophoresis (DGGE) showed that pretreatment methods altered the composition of the microbial community that accounts for hydrogen production. Acid and heat pretreatments were favorable to enrich the dominant hydrogen-producing bacterium, i.e. Clostridium sp., Enterococcus sp. and Bacillus sp., However, besides hydrogen-producing bacteria, much non-hydrogen-producing Lactobacillus sp. was also found in the sludge pretreated with base, freezing and thawing methods. Therefore, based on our results, we concluded that, among the four pretreatment methods using acid, heat-shock, base or freezing and thawing, acid pretreatment was the most effective method for promoting hydrogen production of microbial community. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

An acidic polysaccharide with xylose branches from Porphyra yezoensis

An acidic polysaccharide (PY3) was isolated from the hot water extract of the red algae Porphyra yezoensis by successive column chromatographies over DEAE-cellulose and Sephadex G-200. PY3 with an average molecular weight of 1.8x10(5) was demonstrated to be composed of galactose (Gal), 3,6-anhydrogalactose (3,6-AnGal), 6-OSO3-galactose (6-OSO3-Gal) and xylose (Xyl) in an approximate molar ratio of 25 : 15, 10, 1. In view of Smith degradation and methylation and on the basis of spectral evidence including those of IR, GC, GC-MS, and H-1 and C-13 NMR, the most probable repeating unit of PY3 could be proposed as [(1-->3)beta -D-Gal(1 --> 4)alpha -L-3,6-AnGal](3)-[(1 --> 3)beta -D-Gal(1 --> 4)alpha -L-6-OSO3-Gal](2) with a xylose moiety at the C-6 of one of every twenty-five beta -D-Gal residues. To our knowledge, PY3 was shown to be the first porphyran possessing occasional xylose branches.

Mean sea surface heights of the South and East China Seas from ocean circulation model and geodetic leveling

The mean sea surface heights (sea surface topography) of the South China, East China, Yellow and Bohai Seas are derived from an ocean general circulation model and surface air pressure. The circulation model covers the global oceans, with fine grid (1/6degrees) covering the East Asian marginal seas and coarse grid (31) covering the rest part of the global oceans. The result shows that the China 1985 National Altitude Datum is 24.7 cm above the me-an sea surface height of the world oceans. The mean sea surface in the coastal ocean adjacent to China is higher in the south than in the north. Intercomparison of the model results with the geodetic leveling measurements at 28 coastal tidal stations shows a standard deviation of 4.8 cm and a fitting coefficient of 95.3%. After correction through linear regression, the standard deviation is reduced to 4.5 cm. This indicates that the accuracy of model results is sufficient for practical application. Based on the model results, the mean sea surface heights for the study area with a resolution of 1/6 degree are given. This result also links the mean sea levels at islands with those on the mainland coast and gives the mean sea surface heights at tidal stations in the Taiwan Island, the Dongsha Islands, the Yisha Islands and the Nansha Islands relative to the China 1985 National Altitude Datum.

Simultaneous Determination of Multi-Organotin Compounds in Seawater by Liquid-Liquid Extraction-High Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry

The hyphenated technique of high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) was applied to the simultaneous determination of five organotin compounds (trimethyltin, dibutyltin, tributyltin, diphenyltin and triphenyltin) in seawater samples. Agilent TC-C18 column was used for the separation, the mobile phase of HPLC was CH3CN : H2O: CH3COOH=65 : 23 : 12 (phi), 0.05% TEA, and pH value was adjusted to 3.0 by diluent ammonia. The flow rate was 0.6 mL . min(-1). Five mixed organotin compounds in a mix standard solution from 100 to 0.5 mu g . L-1 were applied for the method assessment. The experimental results indicate that the correlation coefficient of calibration curves (R-2) for each organotin compound was over 0.998 and the detection limits of the five organotin compounds were lower than 3 ng . L-1. Different mixed organic solvents including dichloromethane or toluene were used for extraction of organotin and the extraction condition of organotin from seawater was optimized. The 100 mL seawater acidized by hydrochloric acid was extracted by 10 mL carbon dichloride (CH2Cl2) with 2% tropolone for 10 min twice. Extracted organic solvents were mixed And blown to one drop by nitrogen with the rate of 1.7 mL . min(-1), then 1 mL acetonitrile was added to the drop for redissolving the organotin compounds. Finally, the mixed redissolution was filtered by 0.22 mu m organic filter membrane before analysis. it was found that the only organotin compound in seawater was triphenyltin (TPHT) and the content was 53.2 ng . L-1. The recoveries test from the standard addition for diphenyltin (DPHT), dibutyltin (DBT), tributyltin (TBT) and triphenyltin (TPHT) were over 80%. However, the recovery for trimethyltin (TMT) was relatively low and the value was 50%. The reason might be attributed to the decomposition or adsorption of those compounds during the extraction procedure. Further study on this subject is in progress.

具有随机机器故障的制造过程建模与性能分析

为研究机器故障和维修活动对制造过程性能的影响,提出一种基于广义随机Petri网的制造过程建模与性能分析方法。分析了随机机器故障特征;定义了两种故障发现模式和两种中断作业处理策略;给出具有随机机器故障的制造过程的不同模型方法;通过对模型结构特征的分析,证明了其有效性。针对不同策略和参数设置进行了性能仿真。分别以平均产量和平均过程流时间等性能指标,分析了单个工作站的性能;采用平均产量,分析了具有两个工作站的流水线的性能。仿真结果表明,故障率、平均维修时间、缓存数量配置、维修工人数量、故障发现模式和中断作业处理策略是影响具有随机机器故障的制造过程性能的主要因素。