Linear and nonlinear AC susceptibility studies in La(Mn1−xCux)O3

The linear and nonlinear AC susceptibility as a function of temperature were measured on LaMn_1−xCu_xO₃ compounds for x=0.05–0.30$x=0.05–0.30$. Samples with x?0.10$x?0.10$ exhibit paramagnetic to ferromagnetic transitions followed by low temperature spin glass like transition. The linear susceptibility exhibits strong frequency dependence and is analyzed in terms of standard theoretical model for spin glass. The magnitude and peak temperature of nonlinear susceptibility vary with AC field amplitudes. They are analyzed in terms of critical behaviour in the vicinity of spin glass transition temperature and the critical exponent is found to be 3.2.     

Destabilization of a viscous film flowing down in the form of a vertical cylindrical curtain

In this Letter, we study experimentally a viscous liquid curtain in an annular geometry. Gap and median radius can be varied in such a way that the base of the initially stationary cylindrical curtain is led to oscillate by decreasing the flow rate. Standing and traveling waves in the plane of the annulus are observed and a nontrivial expression linking pulsation to flow rate per surface unit and viscosity can be defined.     

Experimental and theoretical investigations of the inelastic and reactive scattering dynamics of O(3p) + D2

This paper presents a combined experimental and theoretical study of the dynamics of O((3)P) + D(2) collisions, with emphasis on a center-of-mass (c.m.) collision energy of 25 kcal mol(-1). The experiments were conducted with a crossed-molecular-beams apparatus, employing a laser detonation source to produce hyperthermal atomic oxygen and mass spectrometric detection to measure the product angular and time-of-flight distributions. The novel beam source, which enabled these experiments to be conducted, contributed unique challenges to the experiments and to the analysis, so the experimental methods and approach to the analysis are discussed in detail. Three different levels of theory were used: (1) quasiclassical trajectories (QCT), (2) time-independent quantum scattering calculations based on high-quality potential surfaces for the two lower-energy triplet states, and (3) trajectory-surface-hopping (TSH) studies that couple the triplet surfaces with the lowest singlet surface using a spin-orbit Hamiltonian derived from ab-initio calculations. The latter calculations explore the importance of intersystem crossing in the dynamics. Both experiment and theory show that inelastically scattered O atoms scatter almost exclusively in the forward direction, with little or no loss of translational energy. For the reaction, O((3)P) + D(2) --> OD + D, the experiment shows that, on average, approximately 50% of the available energy goes into product translation and that the OD product angular distributions are largely backward-peaked. These results may be interpreted in light of the QCT and TSH calculations, leading to the conclusion that the reaction occurs mainly on triplet potential energy surfaces with, at most, minor intersystem crossing to a singlet surface. Reaction on either of the two low-lying reactive triplet surfaces proceeds through a rebound mechanism in which the angular distributions are backward-peaked and the product OD is both vibrationally and rotationally excited. The quantum scattering results are in good agreement with QCT calculations, indicating that quantum effects are relatively small for this reaction at a collision energy of 25 kcal mol(-1).     

Triplex formation with alpha-L-LNA (alpha-L-ribo-configured locked nucleic acid)

Using UV melting and CD spectroscopy, we show that alpha-l-LNA-modified oligonucleotides possess the ability to form triplexes at pH 6.8 with significantly increased thermostability relative to DNA triplexes.     

CAN-promoted, diastereoselective synthesis of fused 2,3-dihydrofurans and their transformation into tetrahydroindoles

The reaction between 1,3-cyclohexanediones and chalcones (or their vinilogs) in the presence of 2.5 equiv of cerium(IV) ammonium nitrate afforded trans-2-arylcarbonyl-3-aryl (or styryl)-2,3,6,7-tetrahydrobenzofuran-4(5H)-ones in good to excellent yields and in high diastereoselectivities. The method was also extended to the preparation of derivatives of the 5,6-dihydro-2H-cyclopenta[b]furan-4(3H)-one system. The fused 2,3-dihydrofuran derivatives were transformed into 1-alkyl-2-acyl-3-aryl-6,7-dihydroindole-4(5H)-ones by 2,3-dehydrogenation followed by reaction with primary amines. The direct reaction of the tetrahydrobenzofuran-4(5H)-one compounds derived from dimedone with amines gave 1-alkyl-2-alkylimino-3-aryl-6,7-dihydroindole-4(5H)-ones, while starting materials derived from 1,3-cyclohexanedione underwent an unprecedented 2-deacylation reaction and gave 1-alkyl-3-aryl-6,7-dihydroindole-4(5H)-ones.     

Syntheses and crystal structures of cadmium(II)X2-hexamethylenetetramine (X = Br/I/SCN) coordination polymers having different dimensionality

Four new coordination polymers of cadmium(II) with hexamethylenetetramine (htm) have been synthesized and characterized by routine physicochemical techniques as well as by X-ray single crystal structure analysis. They are [CdBr(htm)(SCN)(H₂O)₂·CH₃OH]_n (1), [CdI(htm)(SCN)(H₂O)₂·0.5(CH₃OH)]_n (2), [Cd₂(htm)₃(SCN)₄(H₂O)]_n·nH₂O (3) and [Cd₃Br₆(htm)₂(H₂O)₅·(htm)(H₂O)₆]_n (4). Complexes 1, 2 and 3 exhibit 1D polymeric structure and complex 4 shows a 2D undulated layered arrangement, containing Cd₆(htm)₆ hexagonal units as building block, which extended to a 3D supramolecular architecture through hydrogen bonding. Thorough thermal investigation suggest that as far as the thermal stability of Cd(II)-htm bond is concerned it attains the maximum in complex 1 and minimum in complex 4. In case of complex 3 the thermal study inferred that CdS end product was obtained at ∼730 °C, whereas in case of other complexes the thermally stable end product remained unidentified. Solid state fluorescence study shows that all the complexes are luminescent at room temperature except complex 3.     

Synthesis and catalytic epoxidation potential of oxodiperoxo molybdenum(VI) complexes with 2-hydroxybenzohydroxamate and 2-hydroxybenzoate: the crystal structure of PPh<Subscript>4</Subscript>[MoO(O<Subscript>2</Subscript>)<Subscript>2</Subscript>(HBA)]

(PPh₄)₂[MoO(O₂)₂(SHAH)]·H₂O and PPh₄[MoO(O₂)₂(HBA)] (SHAH₃ = 2-hydroxybenzohydroxamic acid and HBAH = 2-hydroxybenzoic acid) have been synthesized and characterized by physico-chemical and spectroscopic methods. In addition, the second complex has been structurally characterized by single-crystal X-ray diffraction analysis. We have compared the catalytic activities of these two new complexes, together with the previously reported PPh₄[MoO(O₂)₂(BZ)] (BZH = benzoic acid), with respect to the epoxidation of alkenes. The hydroxamate complex is the most efficient catalyst among the three complexes, showing excellent catalytic activity for the substrates cyclohexene, cyclooctene, cinnamyl alcohol, pent-4-en-1-ol and hex-1-ene.     

An inventory model for a deteriorating item with displayed stock dependent demand under fuzzy inflation and time discounting over a random planning horizon

An inventory model for a deteriorating item (seasonal product) with linearly displayed stock dependent demand is developed in imprecise environment (involving both fuzzy and random parameters) under inflation and time value of money. It is assumed that time horizon, i.e., period of business is random and follows exponential distribution with a known mean. The resultant effect of inflation and time value of money is assumed as fuzzy in nature. The particular case, when resultant effect of inflation and time value is crisp in nature, is also analyzed. A genetic algorithm (GA) is developed with roulette wheel selection, arithmetic crossover, random mutation. For crisp inflation effect, the total expected profit for the planning horizon is maximized using the above GA to derive optimal inventory decision. On the other hand when inflationary effect is fuzzy then the above expected profit is fuzzy in nature too. Since optimization of fuzzy objective is not well defined, the optimistic/pessimistic return of the expected profit is obtained using possibility/necessity measure of fuzzy event. Fuzzy simulation process is proposed to determine this optimistic/pessimistic return. Finally a fuzzy simulation based GA is developed and is used to maximize the above optimistic/pessimistic return to get optimal decision. The models are illustrated with some numerical examples and some sensitivity analyses have been presented.     

腙基席夫碱配体铜(Ⅱ)配合物的合成、结构表征、生物活性和密度泛函理论计算

以甲醇为介质,合成了3种新的席夫碱配体HL¹(2-hydroxybenzaldehyde2-(2-oxo-1,2-diphenylethylidene)hydrazone)、HL²(4-hydroxybenzaldehyde2-(2-oxo-1,2-diphenylethylidene)hydrazone)和 L³(2-methoxybenzaldehyde2-(2-oxo- 1,2-diphenylethylidene)hydrazone)的Cu(Ⅱ)配合物1~3。通过元素分析、光谱方法、磁化率测量和密度泛函理论(DFT)计算对配合物进行了表征。通过单晶X射线衍射研究对合成的配体进行了结构表征。通过DFT计算确定了配合物的优化结构。通过紫外可见吸收光谱和荧光发射光谱研究了配合物与小牛胸腺DNA(CT-DNA)的结合能力。吸收光谱研究揭示了增色效应,并提出了与CT-DNA相互作用的可能模式。溴化乙锭(EB)竞争结合研究表明,配合物可以取代 DNA-EB 加合物中的 DNA,且配合物可能以嵌入模式与 CT-DNA结合。配合物对革兰氏阴性肺炎克雷伯菌、大肠杆菌、鲍氏志贺菌和革兰氏阳性金黄色葡萄球菌的体外抗菌活性研究表明,配合物2对肺炎克雷伯菌和鲍氏志贺菌具有明显抗菌活性,但配合物1和3没有表现出任何显著的抗菌活性。