钇对金属陶瓷力学性能和组织的影响

研究了添加钇对Ｔｉ（Ｃ，Ｎ）基金属瓷力学性能和组织的影响。结果表明，加入适量的钇能提高Ｔｉ（Ｃ，Ｎ）基金属陶瓷的抗变强度和硬度，其原因是由于钇与杂质硫起反应在化合物，净化了陶瓷相－金属相，陶瓷相－陶瓷相界面提高子界面结合强度     

Syntheses and characterizations of three-dimensional channel-like polymeric lanthanide complexes constructed by 1,2,4,5-benzenetetracarboxylic acid

The hydrothermal reaction of YbCl(3) small middle dot6H(2)O with 1,2,4,5-benzenetetracarboxylic dianhydride resulted in [[Yb((b)btec)(1/4)((d)btec)(3/6)(H(2)O)(2)](4).6H(2)O](n)() (1) (H(4)btec = 1,2,4,5-benzenetetracarboxylic acid), and the solvothermal reaction of Er(NO(3))(3) small middle dot6H(2)O or TbCl(3).6H(2)O with 1,2,4,5-benzenetetracarboxylic dianhydride in H(2)O/acetic acid gave rise to [[Er(2)((c)btec)(2/4)((e)btec)(2/4)((f)btec)(2/4)(H(2)O)(4)].4H(2)O](n)() (2) and [[Tb(H(2)btec)(2/4)((f)btec)(3/6)(H(2)O)].2H(2)O](n)() (3), respectively. Complex 1 crystallizes in monoclinic space group C2/m with a = 20.8119(5) A, b = 17.6174(1) A, c = 5.7252(2) A, beta = 92.324(1) degrees, and Z = 1. 1 possesses a three-dimensional framework consisting of eight-coordinate ytterbium centers and two kinds of channels along the c axis. Complex 2 crystallizes in triclinic space group P with a = 9.6739(5) A, b = 11.0039(5) A, c = 11.5523 A, alpha = 104.8330(10) degrees, beta = 91.0000(10) degrees, gamma = 114.2570(10) degrees, and Z = 2. 2 has a three-dimensional framework comprising both eight- and nine-coordinate erbium centers and channels along the a axis. Complex 3 crystallizes in monoclinic space group P2(1)/n with a = 10.7246(12) A, b = 7.1693(9) A, c = 17.158(2) A, beta = 97.109(2) degrees, and Z = 4. 3 shows a three-dimensional framework containing nine-coordinate terbium centers and channels along the b axis. Uncoordinated water molecules occupy the channels in the three complexes. TGA and XRPD were determined for the three complexes, and the results illustrate that the framework of 1 is retained upon removal of uncoordinated and coordinated water molecules.     

Highly efficient rhodium/monodentate phosphoramidite catalyst and its application in the enantioselective hydrogenation of enamides and alpha-dehydroamino acid derivatives

An easily prepared and highly efficient monodentate phosphoramidite ligand derived from BINOL, (S)-2,2'-O,O-(1,1'-binaphthyl)-dioxo-N,N-diethylphospholidine, was examined in the hydrogenation of both enamides and alpha-dehydroamino acid derivatives. The catalyst provided remarkably high enantioselectivities (up to 99.6% ee for enamides and >99.9% ee for alpha-dehydroamino acid derivatives).     

Speciation analysis of aluminium(III) in natural waters and biological fluids by complexing with various catechols followed by differential pulse voltammetry detection

The biological effects of aluminium have received much attention in recent years. Speciation of Al is of basic relevance as it concerns its reactivity and bioavailability. A differential pulse voltammetry (DPV) procedure is proposed for speciation analysis of Al(III) in natural waters and biological fluids using six catechols (L-dopa, dopamine, epinephrine, norepinephrine, caffeic acid and o-benzenediol) as electroactive ligands. The decrease of the DPV anodic peak current for each catechol ligand is linear with the increase of Al concentration. This speciation analysis idea is based on the measurement of the complexation capacity, namely, different affinities of Al(III) for catechols and organic ligands under two pH conditions. The labile monomeric Al fraction (mainly inorganic aluminium) is determined at pH 4.6, while the total monomeric Al fraction is determined at pH 8.5. The principle for Al(III) speciation analysis by an electrochemical method is discussed. This sensitive and simple fractionation method is successfully applied to the speciation analysis of Al in natural waters and the results agree well with those of Driscoll's method. The speciation analysis of Al in biological fluids is also explored and the results are compared with those obtained by ultrafiltration and dialysis. Compared with other speciation protocols the electrochemical method possesses some remarkable advantages: rapidity, high sensitivity, cheap instrumentation and a simple operation procedure.     

A Novel Environmentally Benign Method for the Selective Oxidation of Alcohols to Aldehydes and Ketones

In the presence of [Ru(terpyridine)(2,6‐pyridinedicarboxylate)], aliphatic and benzylic alcohols are oxidized to the corresponding aldehydes or ketones with high selectivity by using hydrogen peroxide as the oxidant. There is no need for the addition of co‐catalysts or organic solvents. By applying an optimized reaction protocol, high catalyst productivity (turnover number>10 000) and activity (turnover frequency up to 14 800 h^?1) has been achieved.     

Chemical Constituents from Cynoglossum gansuense

Two new alkaloids, i.e., (2,3‐dihydro‐1‐oxo‐1H‐pyrrolo[1,2‐a]pyrrol‐7‐yl)methyl (2S*,3S*)‐3‐[(β‐D ‐glucopyranosyl)oxy]‐2‐hydroxy‐2‐(1‐methylethyl)butanoate ( 1 ) and 1,2‐dihydro‐8‐methoxy‐2‐oxoquinoline‐4‐carboxylic acid ( 2 ), were isolated from the alcoholic extract of the whole plant of Cynoglossum gansuense, together with twelve known compounds Their structures were characterized by means of spectroscopic methods, especially by ¹H‐, ¹³C‐, and 2D‐NMR, as well as by HR‐MS experiments and comparison with literature data.     

化学计量学研究及其应用

本文介绍了化学计量学的产生、发展、研究内容及主要应用,对有关工作进行了评述。     

Study on the Phase Diagram of CsCl-CeCl3-HCl(11%)-H2O System and the Properties of the Compounds

The equilibrium solubility of CsCl-CeCl3-HCl(11%)-H2O qua-ternary system at 25℃ has been determined by the physicchemical analysis method ,and the phase diagram was plotted, Two new double salts 3CsCl.CeCl3.3H2O and CsCl.CeCl3.4H2O obtained from the complicated system were identified and characterized by XRD,TG-DTA ,DSC,UV and fluorescence spectroscopy, Studies on the fluorescence excitation and emission show that 3CsCl.CeCl3.3H2O and CsCl.CeCl3.4H2O have upconversion luminescence of infrared-visible range,and the upconversion emission intensity increases with the increase of ratio of CeCl3 in CsCl.     

A novel hyperbranched polyester acrylate used for microfabrications

A novel hyperbranched polyester acrylate (HPEA) was synthesized based upon ethylenediamine tetraacetic acid as a “core” molecule, 5‐hydroxyisophthalic acid as an AB₂ monomer, and 2‐hydroxyethyl acrylate as an endcapping reagent. The obtained oligomer has an unsaturation concentration of 4.10 mmol_C?C g^?1 measured by nuclear magnetic resonance and a wide molecular weight distribution of 1.64 measured by gel permeation chromatography. The two‐photon absorption (TPA) photopolymerization of HPEA under the exposure of a Ti : sapphire femtosecond laser with a wavelength of 800 nm was investigated through laser exposure dose‐dependant spatial resolutions of its resins. The TPA photopolymerization thresholds at the range 1.6–4.3 × 10⁷ mJ cm^?2, and exposure dose windows at the range 3.4–4.3 for three formulations were determined. A spatial resolution of 0.85 μm was obtained through the TPA photopolymerization of the formulation containing 1 wt% photoinitiator and 0.3 wt% photoinhibitor. A diffraction grating and real three‐dimensional coupled gear wheel created by TPA photopolymerization were described to demonstrate the unique capability of HPEA in microfabrications. Copyright © 2004 John Wiley & Sons, Ltd.