bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrothermal Alteration of Andesite in Acid Solutions: Experimental Study in 0.05 M H2SO4 Solution at 110 °C
Authors: Fang Jiann‐Neng , Lo Huann‐Jih , Song Sheng‐Rong , Chung San‐Hsiung , Chen Yaw‐Lin , Lin I‐Chieh , Yu Bing‐Sheng , Chen Huei‐Fen , Li Li‐Jun , Liu Chia‐Mei 
Published: May 2015

AbstractHydrothermal experiments on an andesite have been carried out under the condition of 110 °C, autogeneous pressure, 0.05 M H2SO4 solution and renewal of acid solution every 6 hours.The experimental results indicate that the plagioclase and pyroxenes in the treated samples show micropits and microfractures. Small crystals readily suffered from alteration, as compared with large ones, and the susceptibility of the minerals to the acid solution is decreased in the order of plagioclase, augite, hypersthene and opaque minerals. Plagioclase, which is the most reactive mineral in the experiments, shows an increase of SiO2, but a decrease of Al2O3, CaO and Na2O as the experiments proceeded. The chemical change of the treated andesite, it indicates that the relative amounts of SiO2, TiO2, MgO, ΣFeO, MnO and K2O increase, while those of Al2O3, CaO, Na2O and P2O5 decrease with an increase of the experimental duration.The relative mobility of chemical elements listed in decreasing order is P, Ca, Al, Na, Si, K, Mg, Fe, Mn and Ti in terms of the K value. It is no wonder that Ca, Al and Na are more mobile than others because these elements are readily released into solution from the more reactive plagioclase, while Mg, Fe etc. still stay in the less reactive pyroxenes and opaque minerals.
Rice Bran as an Excellent Sorbent for Heavy Metals from Aqueous Media, 1. Optimization of Conditions
Authors: Farajzadeh Mir Ali , Vardast Mohammad Reza 
Published: May 2015

AbstractIn this two‐part report, the efficiency of rice bran in removal of heavy metals such as cadmium, lead, zinc, nickel, copper and iron(III) from aqueous solution is investigated. The different experimental conditions such as pH, temperature, volume of solution, bran amount, particle size, exchange time, stirring speed, etc. are studied, and the optimum conditions are selected in part 1 of this series of reports. The efficiency of bran in removal of heavy metals is presented with and without treatments. For treatment, heat or acid, alkali and salt solutions were used. The results obtained show that after treating with saturated sodium chloride solution, its efficiency for Ni2+ and Zn2+ improves. At pH 5, all studied cations have recoveries more than 93% (lead and cadmium 100%). The exchange speed is very high and has preference over the classical ion exchangers.
The Facile Reversed‐Phase HPLC Resolution of Tetrahydrofurofuran Nucleus Lignans in Traditional Chinese Medicine: Quantitative Analysis of Asarinin and Sesamin in Asari Radix
Authors: Wang Chao‐Chiun , Chen Shushi , Wu Tian‐Shung 
Published: May 2015

AbstractEight tetrahydrofurofuran nucleus lignans: syringaresinol, epi‐syringaresinol, lirioresinol‐B dimethyl ether, xanthoxylol, phillygenin, fargesin, sesamin and asarinin are separated on a C18 column in the reversed‐phase mode. These lignans are plant products formed primarily by the carbon‐carbon coupling of derivatives of cinnamyl alcohol units, in which the two units may be linked by an oxygen bridge to form a tetrahydrofurofuran nucleus and are found to be highly similar in structure. However, these lignans can be baseline resolved under gradient elution in less than 25 minutes. The resolution also can be optimized through altering the flow rate in an isocratic elution. This method is proven to be facile and reliable in routine quantitative analysis of ingredients such as asarinin and sesamin in traditional Chinese medicine Asarum sieboldii. The corresponding recoveries (%) were found to be 95.65 and 96.14, respectively.
Microwave Promoted and Improved Thermal Synthesis of Spiro[Indole‐Pyranobenzopyrans] and Spiro[Indole‐Pyranoimidazoles]
Authors: Dandia Anshu , Singh Ruby , Sachdeva Harshita , Gupta Rajive , Paul Satya 
Published: May 2015

AbstractSpiro[indole‐pyranoimidazoles] (5) and spiro[indole‐pyranobenzopyrans] (6) are readily synthesized in one step in 86–92 and 91–97% yields by the Michael condensation of 3‐dicyanomethylene‐2H‐indol‐2‐ones (2) with 1‐phenyl‐2‐thiohydantoin (3) and 4‐hydroxy‐2H‐1‐benzopyran‐2‐one (4), respectively, without using any catalyst under different reaction conditions (conventional heating and microwave irradiation using (a) polar solvents (b) neutral alumina/silica gel as inorganic solid support in solvent free conditions). 2 was synthesized in situ by the Knoevenagel condensation of indole‐2,3‐dione (1) and malononitrile in the absence of any catalyst.100% conversion was observed in most cases on TLC which also showed the formation of a single product. The comparison between the various methods is established.
A Novel Quantitative Structure‐Biodegradability Relationship (QSBR) of Substituted Benzenes Based on MHDV Descriptor
Authors: Liu Yan , Liu Shu‐Shen , Cui Shi‐Hai , Cai Shao‐Xi 
Published: May 2015

AbstractThe molecular holographic distance vector (MHDV) is employed to characterize the structures of 51 substituted benzenes. 29 descriptors from 91 MHDV ones have nonzero values where 3 descriptors have only one nonzero sample and 1 descriptor only two nonzero samples. A genetic algorithm is used to select an optimal combination of the variables from the remaining 25 nonzero descriptors. Then the optimal descriptors are employed to relate to the relative biodegradability using multiple linear regression method. The 6‐variable linear model developed has high quality where the correlation coefficient of estimations and the root mean square error of estimations are 0.9604 and 0.280, respectively, and the correlation coefficient of predictions and the root mean square error of predictions for leave‐one‐out procedure are 0.9471 and 0.324, respectively.
Determination of Thallium by Starch Iodide Method and Its Applications in Environmental Samples
Authors: Asthana Anupama , Pillai Ajai , Gupta V. K. 
Published: May 2015

AbstractThe present method for determination of thallium involves the oxidation of Tl(I) to Tl(III), with bromine water and liberation of iodine by Tl(III) from potassium iodide in acidic medium. The liberated iodine is reacted with starch to form a blue coloured complex having λmax 575 nm. The system obeys Beer's law in the range of 1–10 μg per 25 mL. The molar absorptivity and Sandell's sensitivity were found to be 1.98 × 105 l mol−1 cm−1 and 0.00098 μg cm−2, respectively. The method has been successfully applied for the determination of thallium in water, industrial effluent, flue dust and biological samples.
Steroids and Flavonoids from Polygonum nodosum pers
Authors: Shen Tong , Jia Zhongjian , Zheng Shangzhen , Shen Xuwei 
Published: May 2015

AbstractTwo new steroids Zhonghualiaoine I (1) and Zhonghualiaoine II (2) were isolated along with seven known compounds from Polygonum nodosum pers (Chinese name “Zhonghualiao”, Berberidaceae). Their structures were deduced on the basis of spectral data.
Routes to Pyrazolo[3,4‐e][1,4]thiazepine, Pyrazolo[1,5‐a]pyrimidine and Pyrazole Derivatives
Authors: Elmaati Tarek M. Abu , El‐Taweel Fathi M. A. 
Published: May 2015

Abstract5‐Aminopyrazole 1 was condensed with aryl aldehydes to give the 4‐arylidenes 2. Compound 2 reacted with thioglycolic acid and ethyl cyanoacetate to give the pyrazolothiazepines 3 and pyrazolopyrimidines 4, respectively. Diazotized 2a coupled with resorcinol to give the pyrazole derivative 5a. Reaction of 1a with β‐keto esters 7, 8 and acetoacetanilides 13 afforded the pyrazolopyrimidines 11, 12 and 15, respectively. Condensation of 1a with 2‐acetylindan‐1,3‐dione 16 yielded fused pyrazolopyrimidine 18. Compound 1a also reacted with the enaminonitriles 19 and 22 to give the pyrazolopyrimidine 20 and 24, respectively.
Inhibitory Kinetic‐Fluorimetric Determination of Trace Aniline
Authors: Cheng Ding‐Xi , Zhang Hong‐Wu 
Published: May 2015

AbstractA novel inhibitory kinetic‐fluorimetric method is reported for the determination of trace aniline. The method is based on the inhibitory effect of aniline on the oxidation of rhodamine B by potassium iodate in hydrochloric acid. The detection limit for aniline is 0.872 ng/mL; the linear range of determination is 4.10∼41.0 ng/mL. Every parameter has been optimized. Some ions which seriously interfere with the determination can be removed by means of pre‐distillation in basic condition. The proposed method is simple, rapid and reliable. It has been applied to the determination of trace aniline in waste and tap waters.
Interaction of the Anticancer Drug 8‐Azaguanine with DNA
Authors: Ye Bao‐Xian , Wang Cui‐Hong , Jing Ai‐Hua 
Published: May 2015

AbstractThe interaction of 8‐Azaguanine and fish tests double‐stranded DNA (dsDNA) and fish tests single‐stranded DNA (ssDNA) was studied electrochemically by using differential pulse voltammetry (DPV) and cyclic voltammetry (CV) at wax‐marinated graphite electrodes (GE) in a 0.2 mol/L acetate buffer (pH 3.6). Different effect factors, such as pH, time, temperature, and DNA concentration were determined. It was observed that the peak current decreased and the peak potential shifted positively with the increasing of time, temperature and DNA concentration, respectively. In addition, the peak current was a linear relationship with DNA concentration in the range of 1 μg/mL ∼ 7 μg/mL. Furthermore, the signals were found to decrease in the order of 8‐AG, 8‐AG‐dsDNA adduct and 8‐AG‐ssDNA adduct, and the signal at a bare electrode was higher than that at the dsDNA‐modified CE. Simultaneously, the electrode reaction process was investigated in detail by some electrochemistry techniques and its dynamics parameters were obtained.
A Detailed Theoretical Study of TiC(001) Relaxed Surface
Authors: Zhang Y. F. , Li J. Q. 
Published: May 2015

AbstractThe geometric and electronic structures of clean TiC(001) surface were investigated using first principles calculations based on generalized gradient approximation density functional theory. The structural optimization of the surface shows that the C and Ti atoms on the top layer move outward and inward, respectively. The results of the band structure calculation indicate that the “active” surface states of TiC(001) surface located around 2.3 eV below Fermi level are originated from 2pz orbital of surface C atoms. Furthermore, the influence of the surface relaxation on the electronic structures, including the charge densities, work functions and surface core level shifts are also discussed in the paper.
A DFT/B3LYP Computational Study of Boron‐Nitride Nanotubes
Authors: Dai Bai‐Qing , Zhang Gui‐Ling , Zhao Jing‐Xiang 
Published: May 2015

AbstractDFT/B3LYP calculations were carried out for a boron‐nitride nanotube (BNNT) of zigzag (N,0) and armchair (N,N), where N = 4,5 and 6, respectively. From a calculated energy band, density of state and bond order, the electroconductivity and bonding character of BNNT were discussed and compared with that of a carbon nanotube (CNT).
Comparison of Different Polarization Schemes in Open‐shell Relativistic Density Functional Calculations
Authors: Wang Fan , Liu Wenjian 
Published: May 2015

AbstractIt is well established that, in addition to the electron density, the spin density has to be used as a basic variable in open‐shell nonrelativistic density functional calculations. This scheme can easily be extended to scalar relativistic density functional theory, since spin symmetry is retained. However, when spin‐orbit coupling is taken into account, an ambiguity arises on how to define a proper “spin density” in four‐ and two‐component open‐shell relativistic density functional calculations, because spin is no longer a good quantum number. In this context, three conceptually different polarization schemes, viz. Kramers‐unrestricted, collinear, and noncollinear, have been proposed. Systematic comparisons are necessary to reveal their performance. Based on four‐component relativistic density functional calculations performed with the BDF program package for the whole p‐block elements, it is shown that the collinear approach should not be used, since it does not provide any conceptual or computational advantages. The Kramers‐unrestricted scheme should instead be used as a replacement. For cases where the magnitude of spin‐orbit coupling is either very small or very large, the Kramers‐unrestricted and noncollinear approaches are very similar to each other. For other cases where there is a strong interplay between exchange and spin‐orbit coupling, they may differ by 0.1 to 0.2 eV. This can be ascribed either to symmetry breaking in the noncollinear approach or to account for more exchange in the Kramers‐unrestricted scheme. For systems with more than one open subshell, the Kramers‐unrestricted scheme is favored due to its maintenance of symmetry (equivalence) and computational ease.
Density Functional Theory Studies of Adsorption and Vibrational Spectra of Hydrogen on the Rh(111) Surface
Authors: Lai Wenzhen , Xiao Haiyan , Xie Daiqian 
Published: May 2015

AbstractDensity functional theory calculations have been carried out for hydrogen adsorption on an Rh(111) surface for three surface cells (2 × 2), (√3 × √3) and (1 × 1). Geometrical structures were optimized to determine the chemisorption energies. The diffusion barriers and vibrational frequencies for hydrogen adsorbed on Rh(111) have also been evaluated. The 3‐fold hollow site was found to be the most stable site. The effect of surface relaxation was also investigated and found to be small. The calculated vibrational frequencies of 80∼105 and 133∼140 meV at the 3‐fold hollow site were attributed to the asymmetric and symmetric stretching modes of H atom, respectively, and in very good agreement with the observed vibrational frequencies of 79∼90 and ∼135 meV.
Density‐Functional‐Theory Calculation of Semiconducting Carbon Nanotubes under an External Electric Field
Authors: Tien Li‐Gan , Liaw Tsong‐Ming , Li Feng‐Yin , Lin Sheng‐Hsien , Lee Ming‐Hsien , Clark Steward 
Published: May 2015

AbstractWe investigate the structure change of semiconducting carbon nanotubes under an external electric field with density functional theory. It is shown that the shape of the nanotube remains cylindrical and the length of the nanotube is also the same, even under a strong electric field. The only change observed is the diameter of the nanotube. It increases along with the increase of the applied electric field.
Experimental and Theoretical Studies of Quantum Beats in Fluorescence
Authors: Chang C. H. , Huang Cheng‐Liang , Ni Chi‐Kung , Dai H. L. , Hayashi M. , Liang K. K. , Kung Andy , Chen I. C. , Lin S. H. 
Published: May 2015

AbstractThe effect of collision on quantum beat is studied theoretically by applying the density matrix method. As an application of this theory, we analyze the experimentally observed quantum beat appearing in the time‐resolved fluorescence profiles of biacetyl. In order to explain complicated fluorescence beating patterns, we present a three‐state model and several important molecular properties are mapped onto this model. We also investigate how quantum beat patterns appear as a function of the number of the triplet states that are involved in the interaction with the singlet state.
Modeling the Binding and Inhibition Mechanism of Nucleotides and Sulfotransferase Using Molecular Docking
Authors: Lin En‐Shyh , Yang Yuh‐Shyong , Yang Jinn‐Moon 
Published: May 2015

AbstractPhenol sulfotransferase (PST) catalyzes sulfuryl group transfer from adenosine 3′‐phosphate 5′‐phosphosulfate (PAPS) to a variety of nucleophilic acceptors in biological systems. Physiological sulfation by PAPS results in the production of adenosine 3′,5′‐diphosphate (PAP). PAP may become a strong inhibitor or cofactor for the physiological or the transfer reactions, respectively. Several nucleotides other than PAP also serve as substrates, inhibitors or cofactors of PST catalyzed reactions. We are interested in the effects of these nucleotides on the PST catalyzed reactions and their possible physiological significance in biology. Several nucleotide inhibitors (such as adenosine 5′‐diphosphate and adenosine 5′‐triphosphate) of sulfotransferase in physiological reactions have been reported in the literature. However, our data suggests that they are not inhibitors for the transfer reaction or the reverse physiological reaction catalyzed by PST. The aim of this work is to show that the molecular docking analysis can be successfully used to underline the inhibition mechanism of these nucleotides. First, the selected compounds were subjected to a detailed docking analysis, by means of GEMDOCK, a program able to reveal the most likely binding mode for each ligand. By comparing these results with binding sites and binding compounds of the nucleotides with known X‐ray structures, it is possible to highlight the site specificity and the inhibition mechanism of the select compounds. The results obtained by the above algorithm were further confirmed experimentally. In this paper, we show the effect of a variety of nucleotides on the activity of sulfotransferase in different docking conditions.
Structural Symmetry Study of Some Protonated Dimer Systems
Authors: Liao Hsin‐Yi , Chu San‐Yan 
Published: May 2015

AbstractThe protonated water dimer has a symmetric structure 2 in contrast to the asymmetric structure of the protonated ammonia dimer 1. To make a general understanding of factors affecting structural symmetry in these protonated dimer systems, we carried out a systematic theoretical study using the B3LYP/6‐31+G** method on several D‐A‐D systems with D as the electron‐pair donors NH3, H2O, and CO and A as the electron‐pair acceptors H+ and Li+. We found the magnitude of the first bonding energy for the monomer (BE(1)) is decisive for the symmetry of the D‐A‐D system. A larger BE(1) leads to a smaller BE(2), the bonding energy of D‐A with the second donor. This gives rise to a stronger tendency towards asymmetry. The magnitude of BE(1) correlates well with the difference in ionization potential (ΔIP) of the orbitals involved in the D‐A interaction. The donor‐donor distance (RD‐D) also plays an important role for the asymmetry, since it is also capable of modifying the ratio of BE(2)/BE(1). The parameter χ, correlated to system asymmetry, defined as RD‐D/RD‐A is a useful parameter insensitive to the type of the system studied, with RD‐A referring to the bond distance in the monomer.
Theoretical Chemical Study on NO Interaction with Cu
Authors: Zhang Yuan , Sun Yueming , Cao Ainian , Liu Juzheng 
Published: May 2015

AbstractResults of quantum calculations on the decomposition of NO to N2O in the presence of Cu are reported. Three approaches of NO interacting with Cu and two decomposition channels via cis‐ and trans‐ (NO)2 dimers have been identified. The configuration of NO approaching the Cu atom with N is more stable than the other two configurations. At low temperature, NO is in favor of decomposing to N2O via the trans‐intermediate Min6 in the presence of the Cu atom, because the decomposition activation energy of this channel is only 61.1 kJ/mol at the B3LYP/Lanl2DZ level, and lower than the other decomposition channel's. The potential energy surface (PES) shows that the cis‐intermediate Min8 is highly stabilized both thermodynamically and kinetically at low temperature, and the calculation results also suggest that the N‐O bond is more easily dissociated than the Cu‐O bond in the Min8. Hence, NO decomposition is very different in the gas phase compared with in the presence of Cu.
Theoretical Calculations on Vibrational Frequencies and Absorption Spectra of S1 and S2 States of Pyridine
Authors: Wu De‐Yin , Hayashi Michitoshi , Shiu Ying‐Jen , Liang Kuo‐Kan , Chang Chung‐Hung , Lin Sheng‐Hsien 
Published: May 2015

AbstractThree harmonic potential‐energy surfaces of 1A1, 1B1, and 1B2 singlet states of pyridine have been obtained by using ab initio method. Geometric properties and force fields of these states have been determined with the complete‐active‐space self‐consistent‐field (CASSCF) theoretical method. Vibrational frequencies of two excited states have been assigned on the basis of the potential energy distribution from normal mode analysis. The resulting properties are used to simulate the experimental absorption spectrum. From the spectral simulation the totally symmetric vibrations with large Huang‐Rhys factors have been identified as ν12 and ν6a modes in the 1B1 state; ν1 and ν12 modes in the 1B2 state, indicating that these modes have strong vibronic coupling between ground and excited states.
Theoretical Study on Intermolecular Interactions of Methyl Azide Dimers
Authors: Xia Qi‐Ying , Xiao He‐Ming , Ju Xue‐Hai , Tan Jin‐Zhi , Gong Xue‐Dong , Ji Guang‐Fu 
Published: May 2015

AbstractThe geometries and electronic structures of methyl azide and its dimers have been calculated by using ab initio method at the HF/6‐311++G** level. The intermolecular interaction energy is calculated with MP2 electron correlation correction, basis set superposition error (BSSE) correction and zero point energy (ZPE) correction. The most stable dimer with binding energy of −10.78 kJ·mol−1 possesses a six‐membered ring with two C‐H···N hydrogen bonds. Natural bond orbital (NBO) analysis is performed to reveal the origin of the interaction. Frequency calculations are carried out on each optimized structure, and IR spectra shifts from the monomer to the dimer are discussed. Based on the vibrational analysis, the changes of thermodynamic properties from the monomer to the dimer with the temperature ranging from 200.00 K to 700.00 K have been obtained using the statistical thermodynamic method.
Theoretical Study of the Inter‐ionic Hydrogen Bonding in the GZT Molecular System
Authors: Chen Cheng , Liu Min‐Hsien , Cheng Sou‐Ro , Wu Lung‐Shing 
Published: May 2015

AbstractDiguanidinium‐5,5′‐azotetrazolate (GZT) is an ionic type high energy compound, which is combined with two guanidinium cations (C(NH2)3+ or defined as G+) and one 5,5′‐azotetrazolate‐2‐anion (ZT2−). The structure of ZT2− is made up of two N4C tetrazole type five‐member rings connected by an azo type (‐N=N‐) linkage. The multi‐nitrogen structure of the compound makes the ZT2− anion in the GZT molecular system a major high‐energy source with the properties of an electron donor. In addition to this, the C(NH2)3+ cation containing H atoms within its NH2 groups behaves like a good charge acceptor not only for the formation of hydrogen bonds but also in regard to the stabilization effect within the whole molecular system. There are four strong inter‐ionic hydrogen bonds in this GZT molecular system combining with the ZT2− anion and the two C(NH2)3+ (or G+) cations. It is impossible to calculate hydrogen bond energy between its ions by a conventional energy difference method because it is difficult to distinguish whether such an energy difference happens simply because of inter‐ionic Coulomb attraction or because of the pure energy of the hydrogen bond. With our newly developed “hydrogen bonding localization analysis methods”, we have successfully calculated the localized hydrogen bond orders and energies of the inter‐ionic hydrogen bonds in the GZT molecular system. When the localized hydrogen bond energy, the bond order, the shortening of the hydrogen bond distance, the elongation of the bond length, and the red shift of stretching frequency of the closely related NH bond are compared in order to determine the hydrogen bonding strength, all the evidence taken together, proves that the four hydrogen bonds in the GZT inter‐ionic molecular system are stronger than most hydrogen bonds existing in all the inter‐molecular and intra‐molecular hydrogen‐bonding problems we have ever considered previously.