bluuebunny/crossref_metadata_2025_split huggingface dataset:
Picosecond Vibrational Spectroscopy of Intermolecular Energy Transfer and Overtone Relaxation in Liquid Bromoform
Authors: Seifert G. , Patzlaff T. , Graener H. 
Published: May 2015

AbstractIntermolecular energy transfer in liquid bromoform and d‐bromoform was investigated by help of picosecond IR and Raman spectroscopy. For a comprehensive interpretation of the corresponding results the study of C‐H bending overtone (2v4) relaxation was necessary; the effective vibrational lifetime of this vibrational mode was determined to T1 = 3±1 ps. For the intermolecular transfer a dominating process between the intramolecularly equilibrated C‐Br stretching modes v2 and v5 of CHBr3 and CDBr3 with a rate constant of 4·1010 s−1 was recognized. Other possible channels, particularly the one between the quasi resonant modes v1(C‐D) and 2v4(C‐H) were found to be negligible.
Ultrafast Charge Transfer Studied by Femtosecond IR‐Spectroscopy and ab Initio Calculations
Authors: Kummrow Andreas , Dreyer Jens , Chudoba Christian , Stenger Jens , Theodorus Erik , Nibbering Johannes , Elsaesser Thomas 
Published: May 2015

AbstractFemtosecond vibrational spectroscopy is a versatile method to monitor excited state dynamics evolving in photochemical reactions. Applying high‐level calculations to analyze infrared absorption spectra allows to elucidate molecular structures of the transient compounds and to assign normal modes to the absorption lines. Striking differences in the experimental vibrational pattern of the locally excited states of 4‐(dimethylamino)benzonitrile (DMABN) and 4‐aminobenzonitrile (ABN) (dissolved in acetonitrile) are explained on the basis of planar and pyramidal structures obtained from ab initio complete‐active‐space self‐consistent‐field (CASSCF) calculations, giving evidence for a strong sensitivity of the molecular structure on modest changes in the substituents. Different models for the charge transfer state of DMABN are evaluated.
A Theoretical Analysis of Absorption Spectra and Dynamics of Photosynthetic Reaction Centers
Authors: Chang Chung‐Hung , Hayashi Michitoshi , Chang Railing , Liang Kuo‐Kan , Yang Tzyy‐Schiuan , Lin Sheng‐Hsien 
Published: May 2015

AbstractIn this work, we construct a microscopic model with which one can reconstruct all the experimentally observed characteristics of the RCs including temperature effects. For this purpose, we analyze the absorption spectra of Rb. sphaeroides RCs (R26 and R26. Phe‐a mutants). We apply the excitonic‐vibronic model with the displaced harmonic potential surface model for the nuclear freedoms and determine microscopic properties such as the electronic coupling constants, the vibrational frequencies, and the displacements among the potential surfaces of these electronic states. We also take into account inhomogeneity of RCs in our theoretical analysis. We introduce a thermal expansion model to treat temperature dependent peak shifts observed in the P band of the absorption spectra of the RCs. With the resulting information, we also calculate the rate constants of the dynamic processes occurring in RCs, determining the electronic coupling constants among the electronic states involved in electron transfer and electronic energy transfer of the RCs. Based on the excitonic‐vibronic model, we also investigate the mechanism of the direct path PB*H → P+B−H recently observed in YM210W mutant.
Generalized Redfield Theory and its Application to Transient Absorption Spectroscopies of Molecules in Condensed Phases
Authors: Yang Chen , Shuang Feng , Yan Yi Jing 
Published: May 2015

AbstractWe present a method of implementing the generalized Redfield theory on the calculation of femtosecond transient absorption spectrum of molecular systems in condensed phases. Numerical demonstration is carried out in a model Brownian molecular system involving two Morse potential surfaces. Intramolecular vibrational relaxation, its relation to the spectral density, its spectroscopic signature, and the temperature effect are analyzed.
Extraction Spectrophotometric Determination of Vanadium in Industrial Waste Water
Authors: Kamavisdar A. , Patel K. S. 
Published: May 2015

AbstractA new and simple extraction spectrophotometric method for the determination of vanadium(V) with KIO4, N‐phenylbenzohydroxamic acid (PBHA) and crystal violet (CV), in industrial waste water samples is described. It is based on the extraction of mixed‐ligand complex V(V)‐IO4− ‐PBHA‐CV+ into chloroform solution over 2‐7 MHC1. The molar absorptivity of the complex is (7.20) × 1031 mol−1 cm−1 at λmax 535 nm. The detection limit of the method is 44 μg 1−1 V. The linearity of the calibration curve is followed up to 6 μgmL−1 in the organic solution with slope, intercept and correlation coefficient of 1.34 × 10−1, 6.7 × 10−3 and +0.99, respectively. This method enhances the sensitivity of the conventional PBHA method for the determination of vanadium, and is free from interferences of other metal ions commonly associated with vanadium. The method has been successfully tested for the determination of V in the industrial waste water samples.
Synthesis of Some New Fu Sed/Spiro of Benzoindole Derivatives and Their Biological Activity
Authors: Soleiman H. A. , Khalafallah A. K. , Abdelzaher H. M. 
Published: May 2015

AbstractA series of fused and spiropyrazolones, pyrimidinthiones, thiazolidinones and β‐lactams incorporating benzoindole derivatives have been synthesised by cyclocondensation addition reaction and cycloaddition reaction of hydrazine hydrate, hydroxylamine, thiourea, mercapto acetic acid and monochloroacetyl chloride. The pre pared com pounds were tested for anti bacterial and fungicidal activity. Gram‐negative bacteria (Bacilluscereus), as well as the fun gus was used for this purpose. The biological assay was determined according to the filter paper disc method. Assay plates were incubated at 30°C one day for the bacteria and three days for the fun gus (British pharmacopoeia commisson, 1102m, London 1963). The test results show that the components have a strong and sat is factory effect.
Synthesis, Characterization and Reactions of 4‐Hydrazino‐2‐methylpyrimidino[4′5′:4,5]thiazolo[3,2‐a]benzimidazole
Authors: El‐Wareth Abd , Sarhan A. O. 
Published: May 2015

Abstract4‐Hydrazino‐2‐methylpyrimidino[4′,5′:4,5]thiazolo[3,2‐a]benzimidazole (4) was obtained from hydrazinolysis of the 4‐chloro derivative 3 with hydrazine hydrate. The hydrazino derivative 4 was further cyclized to the corresponding pyrazole 5, pyrazolone 6 and 5‐methyl‐1,2,4‐triazolo[1″,5″:3′,4′]pyrimidino[5′,6′:5,4]‐thiazolo[3,2‐a]benzimidazole (9) and 5‐methy‐1,2,4‐triazolo[4″,3″:3′,4′]pyrimidino[5′,6′:5,4]thiazolo‐[3,2‐a]benzimidazole (10), respectively. The triazolo derivative 10 was isomerized to the triazolo derivative 9 under a variety of reaction conditions.
Flavonoid Aglycones and Indole Alkaloids from the Roots of Acacia Confusa
Authors: Lee Tzong‐Huei , Chou Chang‐Hung 
Published: May 2015

AbstractFrom the methanolic extract of the roots of Acacia confusa Merr. (Leguminosae), (‐)‐2,3‐cis‐3,4‐cis‐4′‐methoxy‐3,3′,4,7,8‐pentahydroxyflavan (1), (‐)‐2,3‐cis‐3,4‐cis‐3,3′,4,4′,7,8‐hexahydroxyflavan (2), (‐)‐2,3‐trans‐3′,4′,7,8‐tetrahydroxydihydroflavonol (3), (+)‐catechin (4), (‐)‐epicatechin (5), 3′,4′,7,8‐tetrahydroxyflavonol (6) together with N‐methyltryptamine (7) and N,N‐dimethyltryptamine (8) were isolated, and their structures were established by analysis of their spectroscopic data. Among them, compound 1 was a new flavonoid. Additionally, the results of chromatographic bioassay on lettuce seeds indicated that compounds 7 and 8 exhibited significant phytotoxicity at a concentration lower than 14 mM.
Diamino‐Substituted Carbene Transfer between Transition Metal Ions
Authors: Chen Hsin‐Pei , Ku Rong‐Zhi , Liu Shiuh‐Tzung 
Published: May 2015

AbstractDiamino‐carbene ligand transfer between various metalions is studied, particularly with Pd (II) to Rh(I), Rh(I) to Au(I). Reactions of various carbene complexes with AgPF6 result in the cleavage of the M=C bond to give the protonated carbene species, imidazolidin‐2‐ylidinium salt, indicating the presence of free carbene ligand in the reaction medium. When the carbene transfer process was carried out in tetrahydrofuran, the polymerization of tetrahydrofuran occurred.
Electrochemical Response of Polyaniline (PANI)/Thiokol Rubber (TR) Films in Cysteine Solution
Authors: Jia Zhenbin , Ding Keqiang , Zhao Qian , Cao Jianglin , Tong Ruting 
Published: May 2015

AbstractThe electrochemical character of polyaniline/thiokol rubber (PANI/TR) composite film on a Pt electrode was investigated in a cysteine sulphuric acid solution by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The significant change of the peak current and peak potential in the cyclic voltammograms was observed. The irreversible peaks of cyclic voltammetry for cysteine/cystine redox couple at a platinum electrode have turned into one pair of nearly reversible peaks at the above electrode; the reversibility of the redox couple has been greatly improved. We found that thiokol rubber could improve the electrocatalysis of the PANI film to the electrochemical reaction with S‐S bonds, as well as the adhesion of the PANI film to the Pt substrate. Several effective factors, such as the concentration of thiokol rubber in the nonaqueous electrodeposition solution, different potential scan rate, immersing time of the film electrode in the studied electrolyte were all taken into account.
Synthesis of C‐Butenyl Linked Disaccharides via Olefin Cross‐Metathesis
Authors: Lin Chang‐Ching , Subramanian Thangaiah , Hsu Tzu‐Sui , Fan Gang‐Ting , Lin Chun‐Cheng 
Published: May 2015

AbstractSeveral C‐butenyl linked disaccharides were pre pared in high yields by olefin cross‐metathesis.
Synthesis, Acidity Constants and Tautomeric Structure of 7‐Arylhydrazono[1,2,4]Triazolo[3,4‐b][1,3,4]thiadiazines in Ground and Excited States
Authors: Shawali Ahmad S. , Zeid Ibrahim F. , Abdelkader Mahmoud H. , Elsherbini Alsayed A. , Altalbawy Farag M. A. 
Published: May 2015

Abstract7‐Arylhydrazono[1,2,4]triazolo[3,4‐b][1,3,4]thiadiazines 4 were synthesized from the reactions of 4‐amino‐5‐phenyl‐4H‐[1,2,4]triazole‐3‐thiol 2 and 2‐(2‐naphthyl)‐2‐oxoethanehydrazonoyl bromides 1 and their acid dissociation constants pK and pK*, in the ground and excited states, respectively, were determined. Both pK and pK* constants were correlated by Hammett equation. The pK and the spectral data presented indicate that the title compounds exist predominantly in the hydrazone tautomeric form.
Synthesis of Naturally Occurring Rubilactone, Mollugin, and Dihydromollugin of Rubia cordifolia
Authors: Ho Li‐Kang , Yu Hsi‐Jung , Ho Chen‐Ta , Don Ming‐Jaw 
Published: May 2015

AbstractRubilactone (1), dihydromollugin (2), and mollugin (3) are naturally occurring products found in Rubia cordifolia, which is a famous Chinese herb with anti tumor, viral inhibition and other activities. Synthetic studies were carried out in these naphthoic acid esters starting from 1,4‐dihydroxy‐2‐naphthoic acid. In this study, we finished the synthesis of rubilactone which has not been reported before and also synthesized dihydromollugin and mollugin with better yields with different approaches compared to those previously reported in the literature.
Dry Diazonium Nitrates from Aromatic Amines and Tributyl Phosphate‐NO2 Adduct
Authors: Zhang Qingzhi , Liu Xinming , Zhang Shensong , Zhang Jinming 
Published: May 2015

AbstractAromatic amines reacted with TBP‐NO2 adduct to give dry aryl diazonium nitrate in high purity and yield.
Time‐Resolved Extended X‐ray Absorption Fine Structure (EXAFS) Studies by Means of an Energy Dispersive Spectrometer
Authors: Oulianov Dmitri A. , Tomov Ivan V. , Lin Sheng H. , Rentzepis Peter M. 
Published: May 2015

AbstractThe structures formed during the photodicosiation of CBr4 in alcohol solution have been measured by means of a novel ultrafast time‐resolved x‐ray absorption fine structure (EXAFS) experimental system, suitable for the direct determination of ultrafast transient structures of molecules in the liquid and solid phase. The EXAFS spectra of the starting and final products of the reaction were measured and analyzed.
Concise Synthesis of Sibrafiban and Lamifiban, Two Non‐Peptide Fibrinogen Receptor (GPIIb/IIIa) Antagonists
Authors: Chang Meng‐Yang , Chen Shui‐Tein 
Published: May 2015

AbstractThe total synthesis of the non‐peptide fibrinogen receptor antagonists, sibrafiban (1) (Ro 48–3657) and lamifiban (2) (Ro 44–9883), is described. Both contain 4‐hydroxypiperidine unit and the same solid‐phase synthesis method was used as a key step. Connection of a secondary alcohol to the DHP‐resin, followed by iterative saponification and coupling sequences, provided novel drugs.
Polymer Coated Piezoelectric Quartz Crystal Protein Bio‐Sensors
Authors: Hsu Hui‐Ping , Shih Jeng‐Shong 
Published: May 2015

AbstractA polymer coated piezoelectric crystal detection system with a home‐made computer interface for signal acquisition and data processing was prepared as a liquid chromatographic detector for various proteins. Various polymers, e.g., polyvinyl aldehhyde (polyacrolein) (PVA), polyacrylamide/glutaldehyde (PAA/GA) and bio‐gel A, were used as coating materials on quartz crystals for adsorption of various protein molecules, e.g., catalase (CA), hemoglobin (Hb), α‐chymotrypsin (Ch), albumin (Ab). The frequency responses of the polyacrlein coated piezoelectric detector for various proteins were in the order: catalase> hemoglobin> α‐chymotrypsin > albumin. In contrast, the order of the frequency responses of bio‐gel A and polyacrylamide/glutaldehyde coated piezoelectric crystals for these proteins were: hemoglobin> catalase > α‐chymotrypsin ≥ albumin and hemoglobin > albumin > catalase. The polyacrolein coated piezoelectric crystal protein detector exhibited a good linear frequency response with a high sensitivity of about 2.5×103 Hz/(mg/mL) for catalase. In addition, bio‐gel A and polyacrylamide/glutaraldehyde coated crystals were sensitive to hemoglobin with sensitivities of about 4.5×103 Hz/(mg/mL) and 3.0×103 Hz/(mg/mL), respectively. Study of the interference of various organic molecules, e.g., alcohols, amines, ketones and carboxylic acids, in the detection of proteins with theses polymer coated crystals was also made. The polyacrolein coated crystal for proteins under went less interference from various organic molecules than bio‐gel A or polyacrylamide/glutaraldehyde coated crystals. Effects of coating load, concentration of proteins and flow rate of liquid chromatographic eluent were also investigated and discussed.
Indirect Determination of Ascorbic Acid with Ammonium Sulfate and Ethanol by Extraction and Flotation of Copper
Authors: Shen Yi‐Yang , Li Quan‐Min , Wei Wei 
Published: May 2015

AbstractA new method of indirect determination of ascorbic acid with ammonium sulfate and ethanol by extraction and flotation of copper in the presence of thiocyanate has been studied in this paper. The study shows that a small amount of Cu(II) is reduced to Cu(I) by ascorbic acid, then Cu(I) precipitates with SCN−. In the course of phase separation of ethanol from water, the precipitated CuSCN is extracted and stays in the interface of ethanol and water. A good linear relationship is observed between the extraction yield of Cu(II) and the amount of ascorbic acid. The detection limit for ascorbic acid is 1 10−5 M. Every parameter has been optimized and the reaction mechanism has been studied. The method is simple, rapid (5 min) and suffers from few interferences of common anions and cations. It has been successfully applied for the determination of ascorbic acid in pharmaceuticals and fruits.
Total Synthesis of Kaempferol and Methylated Kaempferol Derivatives
Authors: Lee Yean‐Jang , Wu Tsao‐Dong 
Published: May 2015

AbstractKaempferol (1), a natural product from various plants, was synthesized in which the longest linear sequence is only seven steps in over all yields of 47% from commercially avail able 1,3,5‐trimethoxybenzene (10). The methylated kaempferols 2–5 were also pre pared by use of this concise synthetic methodology. The key transformations in this synthesis involved the I2 oxidative‐promoting‐cyclization and DDO oxidative hydroxylation. Several strategies to achieve 1 are provided.
Solvent Effects on Aza‐anionic Cycloaromatization of 2‐(2‐Substituted‐ethynyl)benzonitriles
Authors: Lin Chi‐Fong , Yang Jia‐Huei , Hsieh Pei‐Chen , Lu Wen‐Der , Wu Ming‐Jung 
Published: May 2015

AbstractThe methanolysis of 2‐(2‐aryl ethynyl)benzonitriles is accelerated when the polar aprotic solvents are added, which could enhance the 6‐endo pathway and give isoquinolones, though the 5‐exo pathway is occupied mostly. The yields of products would also be in creased.
Laser Spectroscopic Studies of Transition Metal Containing Radicals
Authors: Cheung Allan S‐C. 
Published: May 2015

AbstractOur recent work on the spectroscopic studies of diatomic transition metal radicals is briefly presented. Various experimental methods to produce transition metal radicals and obtain electronic spectra using laser spectroscopic techniques are reviewed. Our latest results on the A 2Π‐X2Σ+transition of TiN using polarization spectroscopy and the C 4Σ‐X 4Σ− transition of VS using laser induced fluorescence spectroscopy are described and preliminary results on these transitions are reported.
Laser Induced Atomic Coherence and Interference in Cold Atoms
Authors: Yan Min , Rickey Edward G. , Zhu Yifu 
Published: May 2015

AbstractWe report experimental studies of electro magnetically induced transparency and enhancement of third‐order optical nonlinearities in A‐type atomic systems realized in 87Rb atoms cooled and confined in a magneto‐optical trap. We observed complete transparency of a weak probe laser in the A type Rb system with a moderate coupling field. With a third pump laser tuned to a fourth atomic state, the atomic system exhibits the interference‐enhanced third‐order susceptibility and only absorbs two photons, but not one photon. Our experiment demonstrates large nonlinear absorption of the weak probe laser, from which greatly enhanced Kerr nonlinearity in the Rb system is inferred.
Deconvolution of Atomic Photoabsorption Spectra: A Match between Theory and Experiment
Authors: Chang Tu‐Nan , Luo Yuxiang , Fung Hok‐Sum , Yih Tai‐Sone 
Published: May 2015

AbstractWe present in this paper an extension of a recently proposed deconvolution procedure to compare directly the theoretical and experimental spectrum of a doubly excited ultra‐narrow and nearly symmetric resonance in atomic photoabsorption. Our discussion is based on a set of analytical relations in terms of the variations of i) the ratio between the resonance width ¡ and the experimental energy resolution ‐ in the limit when ¡i =‐ ¿ 1 and ii) the column density nl of the media in a photoabsorption experiment.
Angular Momentum Effects in Excited Atoms
Authors: Williams Jim , Yu Dehong 
Published: May 2015

AbstractSpin‐orbit and electron exchange effects may be identified separately through the observation of “integrated” Stokes parameters of the radiation from excited states after impact by spin‐polarized electrons. The principles underpinning the measurements and the techniques are described. Stokes parameters within 2.5 eV of thresh old are discussed for selected excited states of inert gas atoms. The combined effects of electron exchange and the internal spin‐orbit inter action play a significant role in the excitations of the J = 1 and 2 intermediately‐coupled states while electron exchange is the mechanism for the excitation of the J = 3 well LS‐coupled states.
Elastic Electron‐molecule Scattering Cross Sections: Sulphur Hexafluoride and Benzene
Authors: Cho Hyuck , Gulley Robert J. , Buckman Stephen J. 
Published: May 2015

AbstractAbsolute differential cross sections for elastic scattering of electrons from two non‐polar molecules with high polarizabilities, sulphur hexafluoride (SF6) and benzene (C6H6) have been measured: SF6 at 11 incident energies between 2.7 and 75 eV and scattering angles between 10° and 180° and C6H6 at 13 incident energies between 1.1 and 40 eV and scattering angles between 10° and 130°. The magnetic angle‐changing device, based on that of Read and co‐workers, has been used to extend the SF6 measurements to backward angles (130° to 180°) for incident energies below 15 eV. Some features of these measurements, including the agreement with contemporary scattering theory, are reviewed.
The Approach to Asymptotic Behavior in Photoionization
Authors: Pratt Richard H. , Surić Tihomir 
Published: May 2015

AbstractThe high energy behavior of many atomic processes can be understood in terms of the theory of asymptotic Fourier transforms (AFT). In high energy atomic processes initial or final state wave functions will include continuum states of asymptotic plane wave character, and these will often result in a matrix element which can be viewed as a (multi‐dimensional) Fourier transform. The result will be a behavior of matrix elements and cross sections as inverse powers of the asymptotic momenta, associated with singular behaviors of atomic wave functions, which in turn are associated with the singular (Coulomb) behavior of the interaction of the atomic constituents. The situation is complicated by the Coulomb functions which modify these plane wave behaviors; these result in slowly convergent factors (we call them Stobbe factors) which may be explicitly factored out, yielding a matrix element as a product of a Stobbe factor and a residual matrix element which converges rapidly to its asymptotic form. We will illustrate these ideas here in a discussion of single and double non‐relativistic photoionization, though the approach may also be applied to electron scattering (and with excitation or ionization) and in the relativistic case. The main ideas of the approach can already be illustrated in the discussion of ionization of a particle in a central potential. Within this approach we explain both (for single ionization) the persistent high energy deviations from independent particle approximation predictions and (for double ionization) the shake–off and quasi–free contributions. We also discuss the importance of final state interactions and retardation corrections.
Van‐Der‐Waals Vibrations of Aromatic‐Argon Cations Studied by ZEKE Electron Spectroscopy
Authors: Kimura Katsumi 
Published: May 2015

AbstractThis article is to review ‘van der Waals (vdW) vibrations’ which have been observed for many kinds of aromatic‐argon vdW complexes produced in supersonic jets. The main characteristics of zero‐kinetic‐energy (ZEKE) electron spectroscopy for studying vdW complexes are also described briefly. For the aromatic‐argon vdW complexes so far studied, it is pointed out that the stretching mode is in a range of 40–60 cm−1, and the bending mode is in a range of 10–40 cm−1.