Heterocyclic compounds from 3-(4-phenyl) benzoyl propionic acid

3-(4-Phenyl) benzoyl propionic acid was used as the starting material for the synthesisof furanones (2), pyrrolinones (5), pyridazinones (7), benzoxazinones (8) and quinazolinones (9-11). The behaviour of the derivatives of furanones and benzoxazinones toward different nucleophiles is reported.     

Influence of vanadium doping on the behavior of YBa_2Cu_3O_7-y

YBa2Cu3-xVxO7-y(x=0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) superconductors have been prepared. X-ray diffraction shows that the system remains orthorhombic for all compositions studied, but for x > 0.4 V2O5 was detected as an impurity phase. Substitution of V5+ for Cu2+ occurs in the Cu(2) sites on the Cu(2)-O planes. The introduction of the high valence element, vanadium, produces the extra free-electrons. These electrons recombine with the positive carrier of the system. It makes depression of the mobility and the Hall number of YBa2Cu3-xVxO7-v and also results in a depression of TC.     

CHEMILUMINESCENCE AND FLUORESCENCE OF THE EUROPIUM IONS-ADENINE NUCLEOTIDES SYSTEM AND ITS POSSIBLE BIOLOGICAL SIGNIFICANCE

Abstract— Chemiluminescence of the Eu(II)/Eu(III)-adenine nucleotide-H₂O₂ system and fluorescence of the Eu(III)-adenosine triphosphate system have been investigated. The spectral distribution of the chemiluminescence emission has shown an occurrence of three main bands (Λ=470–480,590–620 and ca. 700 nm). The energy transfer process from the adenosine triphosphate molecules to the Eu(III) ions has been observed in the fluorescence spectrum. The examined chemiluminescence and fluorescence spectra show that these both kinds of emission originate from the ⁵ D _***τ⁷F_*** ( n =1–4) transitions in the Eu(III) ions.     

A comprehensive approach for accurate measurement of proton-proton coupling constants in the sugar ring of DNA

Stereo-selectivedeuteration has been explored as an approach for improving the accuracy of NMR-derived, three-bond vicinal proton-proton coupling constants in the 12-base-pair DNA Dickerson sequence [d(CGCGAATTCGCG)(2)]. The coupling constants are useful for DNA structure determination in restrained molecular dynamics calculations. Specifically, the A5 and A6 residues were prepared with the H2" proton stereo-selectively replaced with a deuteron. Deuteration of the H2" leads to a 42-fold reduction in the transverse cross-relaxation rate of the H2' spin, effectively negating the contribution of transverse cross relaxation to the cross peak frequencies and phases. Calculated linewidth and polarization transfer functions indicated that the reduced dipolar interaction is also expected to result in a significant increase in intensity for all cross peaks involving the H1', H2', or H3' spin. The spectral complexity is also reduced by selective deuteration. Time-shared homonuclear decoupling of passive spins during acquisition was implemented, reducing the spin system, in some cases, to an effectively isolated two-spin system. This enables the use of a 90 degrees mixing pulse instead of the 35 degrees pulse commonly used in standard P.E.COSY experiments, leading to an additional 75% increase in signal intensity. Selective excitation pulses were used to reduce the number of increments required in the indirect dimension by as much as a factor of 4. The cumulative improvement in sensitivity is striking, approaching three orders of magnitude per unit time. Separate experiments, referred to as Stripe-COSY and Superstripe-COSY, were optimized for each coupling constant measured. Finally, J-doubling was used to obtain the most accurate peak separations. This comprehensive approach shows promise as an effective method for extracting highly accurate homonuclear vicinal coupling constants in DNA.     

An adaptive control scheme for a continuous plant under Known output delay, unmodelled dynamics, and input saturation

This paper deals with robustness of adaptive control of continuoussystems subject to known output delay, input saturation, unmodelledlinear dynamics, and bounded disturbances. A simple gradient-typealgorithm with a relative deadzone is used. The relative deadzoneis built with an estimated contribution of the unmodelled dynamicsto the system output. The basic tool used for stability androbustness analysis is Gronwall's lemma.     

电感耦合等离子体-发射光谱法（ICP-AES）快速测定饮用水中8种微量元素

用电感耦合等离子体-发射光谱法（ICP-AES）同时快速测定饮用水中微量的铜、铅、锌、铁、锰、镉、铬、砷,具有快速、简便、灵敏度高等优点,精密度为1．2％～8．2％（RSD,n=5）．回收率为90％～110％．     

微米铜丝的低温力学性能测试

针对纤维材料变温环境力学性能测试的需要,在华中科技大学研制的纤维材料试验机的基础上引入了温控装置,从而实现纤维材料在高低温环境下的力学性能测试。采用该装置对不同直径微米铜丝在不同温度、不同拉伸速率条件下的力学性能开展实验研究,测试结果表明弹性模量和抗拉强度随温度的降低而线性增加,屈服强度的变化不太明显。另外,低温环境下微米铜丝的力学性能表现出与其直径相关的尺度效应,而这一现象在常温下一直没有观测到。最后,还研究了拉伸速率对微米铜丝的力学性能影响,结果表明,在现有装置的许用范围之内,拉伸速率对其力学性能的影响不大。     

CC or co bond cleavage in a phenolic lignin model compound: selectivity depends on vanadium catalyst

The aerobic oxidation of a phenolic lignin model compound with a vanadium catalyst results in the oxidative cleavage of the C?C bond between the aryl ring and the adjacent hydroxy-substituted carbon atom. Labeling experiments indicate key mechanistic differences to a previously reported related C?O bond cleavage reaction. The selectivity in C?C versus C?O bond cleavage depends on the choice of the vanadium catalyst.     

Aerobic oxidation reactions catalyzed by vanadium complexes of bis(phenolate) ligands

Vanadium(V) complexes of the tridentate bis(phenolate)pyridine ligand H(2)BPP (H(2)BPP = 2,6-(HOC(6)H(2)-2,4-(t)Bu(2))(2)NC(5)H(3)) and the bis(phenolate)amine ligand H(2)BPA (H(2)BPA = N,N-bis(2-hydroxy-4,5-dimethylbenzyl)propylamine) have been synthesized and characterized. The ability of the complexes to mediate the oxidative C-C bond cleavage of pinacol was tested. Reaction of the complex (BPP)V(V)(O)(O(i)Pr) (4) with pinacol afforded the monomeric vanadium(IV) product (BPP)V(IV)(O)(HO(i)Pr) (6) and acetone. Vanadium(IV) complex 6 was oxidized rapidly by air at room temperature in the presence of NEt(3), yielding the vanadium(V) cis-dioxo complex [(BPP)V(V)(O)(2)]HNEt(3). Complex (BPA)V(V)(O)(O(i)Pr) (5) reacted with pinacol at room temperature, to afford acetone and the vanadium(IV) dimer [(BPA)V(IV)(O)(HO(i)Pr)](2). Complexes 4 and 5 were evaluated as catalysts for the aerobic oxidation of 4-methoxybenzyl alcohol and arylglycerol β-aryl ether lignin model compounds. Although both 4 and 5 catalyzed the aerobic oxidation of 4-methoxybenzyl alcohol, complex 4 was found to be a more active and robust catalyst for oxidation of the lignin model compounds. The catalytic activities and selectivities of the bis(phenolate) complexes are compared to previously reported catalysts.