bluuebunny/crossref_metadata_2025_split huggingface dataset:
Efficient Preparation of Metal Organosols by Phase Transfer
Authors: Ji‐Kuan Zhao , Xiao Chen , Chun‐Jie Yang , Zhen‐Ming Sui , Guo‐Dong Zhang , Yong‐Cun Chai , Jie Liu 
Published: June 2005

AbstractOrganosols of silver and gold nanoparticles stabilized by sodium oleate were prepared with high efficiency by simple phase transfer of their hydrosols to isooctane. Concentrations of sodium oleate and magnesium chloride have crucial effects on the phase transfer efficiency. UV‐visible absorption spectroscopy and transmission electron microscopy have been used to characterize the nanoparticles. A possible phase transfer mechanism was proposed based on the anchoring positions of oleate deduced by molecular modeling calculations.
AM1 Transition State Modeling for the Enantioselectivities in the Chiral Oxazaborolidine‐Catalyzed Reductions of α‐ and β‐Aminoketones
Authors: Jian‐Fen Fan , Yun‐Xiang Lu , Qiu‐Xia Wang , Li‐Fen Wu 
Published: June 2005

AbstractAM1 transition state (TS) models were developed for the enantioselectivities in the reductions of α‐ and β‐aminoketones catalyzed by (S)‐4‐benzyl‐5,5‐diphenyl‐1,3,2‐oxazaborolidine. The result showed that β‐aminoketone gave better enantioselectivity than its α‐analog. Different chiralities of the final products were obtained, R for the former and S for the latter. These semiempirical TS models are consistent with the experimental data.
Study on the Binding Mode of a Co(II) Complex with DNA
Authors: Qing‐Hua Zhou , Pin Yang 
Published: June 2005

AbstractThe mode of binding of CoLCl2, here L=bis(2‐benzimidazolylmethyl)amine, with calf thymus DNA has been investigated by fluorescence measurements, equilibrium dialysis, viscosity experiments and gel electrophoresis. The complex was found to bind but weakly to DNA, with binding constant of 1.96×104 L/mol determind at 20 °C in a solution containing 5 mmol/L Tris‐HCl (pH 7.1) and 50 mmol/L NaCl. Polyelectrolyte theory was applied to analyse these values. Viscosity experiments show that binding did not alter the relative viscosity of DNA with any complexes to an appreciable extent. Electrophoresis test displayed that the compound could not cleave the DNA. These results show that the complex is essentially electrostatically bound to DNA.
Synthesis, Crystal Structures and Properties of Tetrametallic Complexes: [M2(phen)4(FCA)2](ClO4)2·(H2O)2 (M=Zn or Co, phen=1,10‐phenanthroline, FCA=anion of 3‐ferrocenyl‐2‐crotonic acid)
Authors: Jia‐Xiang Yang , Zhang‐Jun Hu , Ze Zhang , Yu‐Peng Tian , Qing‐Liang Liu , Suchada Chantrapromma , Hoong‐Kun Fun 
Published: June 2005

AbstractTwo new complexes [Zn2(phen)4(FCA)2](ClO4)2·(H2O)2 (1) and [Co2(phen)4 (FCA)2](ClO4)2·(H2O)2 (2) (FCA=anion of 3‐ferrocenyl‐2‐crotonic acid, phen=1,10‐phenanthroline) have been synthesized, and characterized by elemental analysis, IR, UV‐Vis spectra, thermal analyses, and single‐crystal X‐ray diffraction. Two M(II) (M=Zn or Co) ions are bridged by two FCA anions with syn‐anti bridging ligands, leading to dimeric cores, [M2(phen)4(FCA)2]2+, and each M(II) ion is six‐coordinated in a distorted octahedral geometry by two chelate phen ligands and two μ2‐carboxylate oxygen atoms from two FCA groups. The M(II)…M(II) intradimer distances are 0.4391 and 0.4462 nm in 1 and 2, respectively. Electrochemical properties of the complexes have been discussed.
Experimental and Density Functional Theory Calculational Studies on 2,3‐Diaryl‐tetrazole‐5‐thione
Authors: Fang‐Fang Jian , Pu‐Su Zhao , Yu‐Xia Ou , Feng‐Li Bei 
Published: June 2005

Abstract2,3‐Diaryl‐tetrazole‐5‐thione (diaryl=diphenyl, di(p‐methylphenyl) and di(p‐chlorophenyl)) has been synthesized and characterized by elemental analysis, IR and electronic absorption spectroscopy. Two of them have also been characterized by X‐ray diffraction analysis. Density functional theory calculations of the structures, charge distribution, natural bond orbital and topological analysis of the three compounds were performed at B3LYP/6‐31G* level. The calculational results are in good agreement with the X‐ray data and show that different substitute group results in different charge distribution, the exocyclic sulfur atom has the biggest negative charge value and this site is the most likely site of protonation and methylation as well as the potential coordination site with metallic ions. The predicted harmonic vibration frequencies were compared with the experimental values. On the basis of vibrational analyses, the thermodynamic properties of these compounds at different temperatures were calculated, which reveal that$ S^{0}_{\rm m} $,$ H^{0}_{\rm m} $and temperatures have good linear correlations. The calculations of second order optical nonlinearity have also been carried out and relatively high molecular hyperpolarizability values of 1.0913×10‐29‐1.6518×10‐29esu were predicted.
Thermodynamics of Solvent Extraction of Thallium(I) with Di(2‐ethylhexyl)dithiophosphoric Acid
Authors: Xing‐Zhi Liu , Da‐Wei Fang , Yan‐Hong Kang , Jun Li , Shu‐Liang Zang 
Published: June 2005

AbstractIn Tl2SO2+Na2SO4+di(2‐ethylhexyl)dithiophosphoric acid+n‐C8H18+water system, the Tl+ equilibrium molalities were measured at ionic strength from 0.1 to 2.0 mol·kg‐1 containing Na2SO4 as supporting electrolyte in aqueous phase and at constant molality of extractant at temperatures from 278.15 to 303.15 K in organic phase. The standard extraction constants K0 at various temperatures were obtained by methods of extrapolation and polynomial approximation. Thermodynamic quantities for the extraction process were calculated.
QCM Coated with Self‐assembled Cystine‐bearing 1,3‐Bridged Calix[4]arenes for Recognizing Gas‐phase Butylamines
Authors: Yuan‐Yuan Li , Hong‐Zong Yin , Xi‐Wen He , Lang‐Xing Chen , Guo‐Zhu Zhang , Jia‐Qi He 
Published: June 2005

AbstractTwo cystine‐bearing 1,3‐bridged calix[4]arenes were used as the coatings of the quartz crystal microbalance (QCM) with gold electrodes. The two calix[4]arene derivatives were self‐assembled onto the gold electrode surface by the covalent attachment between the di‐sulfur and gold. The compound of cystine‐bearing bi‐phenylalanine 1,3‐bridged calix[4]arene (CPC) with longer alkyl chain had better self‐assembled capacity onto the fresh surfaces of gold electrode than that of cystine‐bearing 1,3‐bridged calix[4]arene (CC) with comparably shorter alkyl chain. The modified QCM sensors were used to recognize the butylamine isomers in gas. The results showed that the QCM coated with both compounds had preferential affinity to n‐butylamine, then i‐butylamine, t‐butylamine in the range of low concentrations, indicating that in the recognition process, the steric hindrance effect played an important role when forming complex with guest molecules. When the concentrations of the analytes were increased, the polarity and the magnetism of the butylamine became determinative factors. The reversibility was improved greatly and the equilibrium time was much shorter on the self‐assembled film than on the film obtained by dropping coating.
A Novel and Efficient Process for Preparation of 2,4‐Diphenyl‐4‐methyl‐1‐pentene in Brönsted Acidic Ionic Liquid [Hmim]+B${\rm F}^{-}_{4} $
Authors: Peng‐Rong Zhang , Ji‐Yan Du , Fan Yang , Gang Zou , Jie Tang 
Published: June 2005

AbstractHighly selective dimerization of α‐methylstyrene (AMS) was effected using a Brönsted acidic ionic liquid, [Hmim]+B${\rm F}^{-}_{4} $, as solvent as well as catalyst, providing the industrial high‐value olefin, 2,4‐diphenyl‐4‐methyl‐1‐pentene (1‐PT). The desired dimer 1‐PT could be obtained in 90% yield at 96% conversion in the dimerization of AMS under optimized conditions. Features of the procedure include use of readily available ionic liquid‐catalyst, exclusion of volatile organic solvents, higher selectivity and efficiency for 1‐PT.
Proline Catalyzed Asymmetric Aldol Reaction between Methyl Ketones and 1‐Aryl‐2,2,2‐trifluoroethanones
Authors: Li‐Hua Qiu , Zong‐Xuan Shen , Chang‐Qing Shi , Yan‐Hua Liu , Ya‐Wen Zhang 
Published: June 2005

AbstractDirect asymmetric aldol addition of methyl ketones to 2,2,2‐trifluoro‐1‐phenylethanone and its ring‐substituted derivatives was achieved using L‐proline as a chiral promoter. Various optically active β‐trifluoromethyl‐β‐hydroxy ketones were obtained in almost quantitative yields with moderate enantioselectivities up to 64 % ee.
Syntheses of Benzimidazoles, Quinoxalines and 3,3‐Dihydro‐1H‐1,5‐benzodiazepines Starting from o‐Phenylenediamine
Authors: Yong Cui , Xiu‐Bo Tang , Chang‐Xing Shao , Ji‐Tai Li , Wen‐Hua Sun 
Published: June 2005

AbstractA series of benzo‐fused heteroaromatic compounds with 5‐, 6‐ and 7‐membered rings, such as benzimidazole, quinoxaline and 1H‐1,5‐benzodiazepine derivatives, were synthesized through condensation reaction of o‐phenylenediamine with aryl aldehydes or ketones. The experimental conditions were carefully examined, and the products were characterized by 1H NMR, 13C NMR, MS, IR and elemental analyses. In addition, the structure of a benzodiazaepine derivative with 7‐membered ring was confirmed by single crystal X‐ray diffraction analysis.
One‐pot Synthesis of Bis(dihydropyrimidinone‐4‐yl)benzene Using Boric Acid as a Catalyst
Authors: Shu‐Jiang Tu , Xiao‐Tong Zhu , Fang Fang , Xiao‐Jing Zhang , Song‐Lei Zhu , Tuan‐Jie Li , Da‐Qing Shi , Xiang‐Shan Wang , Shun‐Jun Ji 
Published: June 2005

AbstractA simple effective synthesis of bis(dihydropyrimidinone‐4‐yl)benzene derivatives, using boric acid as catalyst, from isophthalic aldehyde or terephthalic aldehyde, 1,3‐dicarbonyl compounds and urea or thiourea in glacial acetic acid was described. As the expansion of the classical Biginelli reaction, this method has the advantage of excellent yields 83%–94% and short reaction time 0.5–1.5 h.
VSMP for Modeling the Biodegradability of Substituted Benzenes Based on Electrotopological State Indices for Atom Types
Authors: Shu‐Shen Liu , Da‐Qiang Yin , Shi‐Hai Cui , Lian‐Sheng Wang 
Published: June 2005

AbstractThe electrotopological state (E‐state) index was employed to characterize the structures of 51 substituted benzenes. Eleven E‐state indices of the compounds were calculated by the computer program developed in our laboratory. The method for variable selection and modeling based on prediction (VSMP) was used to select an optimal combination of the variables from 11 E‐state descriptors. Then the optimal descriptors were employed to model the relationship between the relative biodegradability of the substituted benzenes and their molecular structures. A novel 5‐descriptor linear model was developed and the model has a high quality with the correlation coefficient and the root mean square error in estimation step being 0.9378 and 0.35, respectively, and these in leave‐one‐out cross‐validation procedure being 0.9210 and 0.39, respectively.
Studies on the Stablest Geometries and CP Bonding Nature in P‐ylide CH2PH3and P‐ylide‐like Radical ·CHPH3
Authors: Yan‐Li Zeng , Ling‐Peng Meng , Shi‐Jun Zheng 
Published: June 2005

AbstractStudies on the geometries, electronic structures and bonding nature of P‐ylide CH2PH3and P‐ylide‐like radical ·CHPH3have been carried out at the level of MP4(SDTQ)/6‐311++G(d,p) and B3LYP/6‐311++G(d,p). The CP bonding nature of them was discussed by means of topological analysis of electronic density. The following conclu‐sions were obtained: the CP bonding nature of the P‐ylide‐like radical is similar to that of the P‐ylide, and π bonds exist in both of them. But there are two electrons in the π bond of P‐ylide, while there is only one electron in the π bond of P‐ylide‐like radical,i.e., there is a single‐electron π bond in the P‐ylide‐like radical. The electron in the π bond of P‐ylide‐like radical appears mainly near the carbon atom. The bond CP in P‐ylide‐like radical is weaker than that in the corresponding product, ·CH2PH2.
Recycling Chiral Organocatalyst (4S)‐Phenoxy‐(S)‐proline for Direct Asymmetric Aldol Reaction in Ionic Liquid (bmim)PF6
Authors: Yan‐Hua Liu , Ya‐Wen Zhang , Yi‐Ping Ding , Zong‐Xuan Shen , Xiao‐Qing Luo 
Published: June 2005

AbstractRoom temperature ionic liquid (bmim)PF6 was evaluated for recycling an organocatalyst (4S)‐phenoxy‐(S)‐proline for direct asymmetric aldol reactions. The desired aldol products were obtained with good yields up to 93.2% and enantioselectivities up to 88.5%, and isolation of the products by simple extraction allowed recycling the ionic liquid containing the immobilized catalyst in subsequent reactions without significant decrease of yields and enantioselectivities.
Synthesis of Fragment Derivatives of Delta Sleep‐inducing Peptide (1‐4) Catalyzed by Enzymes in Organic Solvents
Authors: Hong‐Yan Shen , Gui‐Ling Tian , Yi‐Ying Hong , Heng Li , Yun‐Hua Ye 
Published: June 2005

AbstractSynthesis of two fragment derivatives of delta sleep‐inducing peptide (DSIP) (1‐4), Boc‐Trp‐Ala‐Gly‐GlyNH‐NHPh (1) and Boc‐Trp‐Ala‐Gly‐GlyOEt (2), catalyzed by proteases via 2+2 or 1+3 synthetic routes with different protecting groups at C‐terminal in organic solvents was reported. The yield of N‐Boc tetrapeptide with phenylhy‐drazinyl protecting carboxyl group at C‐terminal (1) was higher than that of N‐Boc tetrapeptide ethyl ester (2) by2+2 route. The factors influencing the synthetic yield of the fragments of DSIP (1‐4) were discussed.
Detection and Analysis of Strong Oscillating Electric Fields in a Picosecond Laser Plasma with the Help of Plasma Satellites of X‐ray Spectral Lines
Authors: Belyaev V. S. , Kurilov A. S. , Matafonov A. P. , Vinogradov V. I. , Lisitsa V. S. , Gavrilenko V. P. , Faenov A. Ya. , Pikuz T. A. , Skobelev I. Yu. , Magunov A. I. , Pikuz S. A. 
Published: June 2005

AbstractX‐ray lines of ions in a solid target interacting with picosecond laser pulses of the intensity ∼3 × 1017 W/cm2 were studied on the “Neodim” laser facility. We observed X‐ray Lyα emission spectra of hydrogen‐like fluorine ions. Satellite lines were also recorded, evidencing the presence of intense plasma oscillations with an amplitude of the electric field larger than 108 V/cm and a frequency of about 1015 s–1. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coulomb instability of dusty particle system in gas‐discharge plasma
Authors: Filinov V. S. , Petrov O. F. , Fortov V. E. , Molotkov V. I. , Khakhaev A. D. , Podrjadchikov S. F. 
Published: June 2005

AbstractAn effective anisotropic potential is proposed for the interaction between dust particles in a gas‐discharge plasma. In addition to the Coulomb repulsion this potential takes into account attraction due to the spatial positive plasma charge originating from focusing of the ionic fluxes by dusty particles. The time evolution of the dust particle kinetic and potential energies from random initial configurations have been investigated by the Brownian dynamics method. Results of our simulation showed that the attraction between dusty particles can be the main physical reason of formation and decay of classical bound dust particle pairs and many particle complexes with low potential energy, while the kinetic energy (temperature) of unbound dust particles and particle oscillating in bound complexes may increase on three order as observed in experiments. In the model without dust particle attraction the bound complexes are absent and increase of kinetic energy is much less pronounced. The influence of the high frequency and low frequency random‐charge fluctuations on the obtained results has been investigated. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface Tension of Plasma Sheath
Authors: Ignatov A. M. , Schram P. P. J. M. , Trigger S. A. 
Published: June 2005

AbstractA simple model is developed for the self‐consistent charging of a dust layer in an electrode plasma sheath, as well as for the force balance in this layer. The anisotropy of the plasma pressure near the plasma boundary makes it possible to introduce the notion of surface tension. The equilibrium charge, the height at which the dust layer levitates above the electrode, and the plasma surface tension are calculated numerically as functions of the dust density. In all of the cases under analysis, the presence of dust is shown to increase the plasma surface tension, which indicates that the plasma sheath may become structurally unstable. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mechanisms for Generating High Energy Electron Beams by Intense Laser Radiation
Authors: Galkin A. L. , Shiryaev O. B. , Romanovsky M. Yu. , Korobkin V. V. 
Published: June 2005

AbstractThe possibility of electron acceleration during the laser radiation relativistic and charge‐displacement selfchanneling is studied theoretically. A new acceleration mechanism related to the formation of an ion cloud traveling in matter with the laser pulse (due to the effect of the ponderomotive force) is considered. The quasistationary electric and magnetic fields generated by the moving ion cloud can accelerate electrons to energies of tens of MeV and result in the formation of an electron beam going forward coaxially with the laser pulse. The angular distribution of accelerated electron calculated matches the experimental results found in the available publications. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Measurements of the Dust‐Ion Momentum Transfer Frequency and Ion Drag Force in Complex Plasmas
Authors: Yaroshenko V. V. , Ratynskaia S. , Khrapak S. A. , Thoma M. H. , Kretschmer M. , Morfill G. E. 
Published: June 2005

AbstractA simple self‐consistent method to estimate the effect of the streaming ions on microparticles in a positive column of a dc discharge plasma is presented. The momentum transfer frequency in dust‐ion collisions and the ion drag force are determined within a wide range of gas pressures, p = 20–120 Pa. The method does not require a priory knowledge of the particle charge, but involves only the particle charge gradient which is recovered from the same experimental data. The method depends only on two experimental quantities: dust particle drift velocity and electric field, thus minimizing the errors in the estimates. Reasonable agreement is found between our force measurements and theoretical predictions, corresponding to the regime of moderate ion‐dust particle coupling. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Studies of Strongly Coupled Plasmas Using Intense Heavy Ion Beams at the Future FAIR Facility: the HEDgeHOB Collaboration
Authors: Tahir N. A. , Deutsch C. , Fortov V. E. , Gryaznov V. , Hoffmann D. H. H. , Lomonosov I. V. , Piriz A. R. , Shutov A. , Spiller P. , Temporal M. , Udrea S. , Varentsov D. 
Published: June 2005

AbstractThis paper shows with the help of numerical simulations that the high intensity bunched beam of uranium that will be available at the future FAIR (Facility for Antiprotons and Ion Research) facility [W.F. Henning, Nucl. Inst. Meth. B, 214 (2004) 211] at Darmstadt, will be a very efficient tool to create High‐Energy‐Density (HED) states in matter (including strongly coupled plasmas) in the laboratory. We have simulated hydrodynamic and thermodynamic response of targets made of different materials including aluminum and lead. These simulations have been carried out using a two‐dimensional hydrodynamic computer code, BIG‐2. Our simulations show that one can create a plasma with a plasma coupling parameter, Γ, of the order of 5. Such plasmas are believed to exist in stars, brown dwarfs and giant planets. Experimental study of such systems is therefore of great importance to our understanding of the universe. It has also been theoretically predicted that the stopping power of strongly coupled plasmas will be less than that of ideal plasmas. This could have very important implications for inertial confinement fusion energy production schemes. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Progress in Measurements of the Electrical Conductivity of Metal Plasmas
Authors: DeSilva A. W. , Rakhel A. D. 
Published: June 2005

AbstractProgress in the exploding wire techniques for the measurements of the electrical conductivity of dense metal plasmas is reviewed. It is demonstrated that the data on the conductivity obtained by means of quite different techniques give results in good agreement. Recent results of direct measurements of the conductivity, internal energy and density of tungsten over a wide density and temperature ranges are presented. It is speculated that the data may lead to improvements in the conductivity and EOS databases. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Equation of State of Fluid Hydrogen
Authors: Kremp D. , Bezkrovniy V. , Kraeft W. D. , Schlanges M. 
Published: June 2005

AbstractA review is given about some selected aspects of the development of the equation of state of hydrogen. Recent results are presented for low temperature fluid hydrogen. Reaction Ensemble Monte Carlo data determined thus are combined with Path Integral Monte Carlo results to give an Hugoniot covering the entire pressure range. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear Ionic Excitations, Dynamic Bound States, and Nonlinear Currents in a One‐dimensional Plasma
Authors: Chetverikov A. , Ebeling W. , Velarde M. G. 
Published: June 2005

AbstractWe study the role of nonlinear effects in a classical one‐dimensional model of a conducting electron–ion system. In particular we investigate the excitations of strongly nonlinear deformed phonons (cnoidal waves, solitons) on electric currents. We show that in a nonlinear lattice a new type of dynamic bound states of solitons and electrons (“solectrons”) may be formed. In our simulations we use Langevin dynamics with N = 10 ions and periodic boundary conditions. The electron‐ion interaction is modelled by screened Coulomb forces with appropriate cut‐off at small distance; the ion‐ion interaction is approximated by an exponential repulsion. Under the influence of a weak external electrical field, the charged particles and “solectrons” yield a stochastic current in the direction of the field. We study several mechanisms to generate and maintain the “solectrons”. Then we show how the system develops driven ionic solitons moving opposite to the field. Since the extra current driven by the solitons is (nearly) independent on the external field we find a strongly nonlinear current field characteristics corresponding for small fields to a highly conducting state. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Density functional calculations of the reflectivity of shocked xenon with ionization based gap corrections
Authors: Desjarlais M. P. 
Published: June 2005

AbstractExperimental results [1] for the reflection coefficient of shock compressed xenon are compared with results from quantum molecular dynamics calculations with density functional theory (DFT). The real part of the optical conductivity is calculated within the Kubo‐Greenwood formalism and the Kramers‐Krönig relations are used to generate the reflectivity and other optical properties. Improved agreement over non‐ideal plasma theory [2] is found with the DFT calculations, but significant differences with the data remain. Since DFT in the various local density approximations tends to underestimate the band gap and overestimate the free electron population, we have used the ionizations from [2] to correct the DFT band gaps. This results in much improved agreement with the xenon reflectivity data and demonstrates a new approach to correcting DFT band gaps. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)