bluuebunny/crossref_metadata_2025_split huggingface dataset:
Asymmetric Total Synthesis of (−)‐Cladospolide B
Authors: WANG Wen‐Kuan , ZHANG Ji‐Yong , HE Jin‐Mei , TANG Shi‐Bing , WANG Xiao‐Lei , SHE Xue‐Gong , PAN Xin‐Fu 
Published: June 2008

AbstractAn enantioselective total synthesis of (−)‐cladospolide B was described. The key steps in this synthesis include(a) a Sharpless asymmetric dihydroxylation to elaborate syn diol at C‐4 and C‐5 positions; (b) a Mitsunobu esterification to reverse the configuration at C‐11 from (S) to (R); and (c) a ring‐closing metathesis to access the 12‐membered macrocyclic ring.
Highly Efficient Biomimetic Oxidation of Sulfide to Sulfone by Hydrogen Peroxide in the Presence of Manganese meso‐Tetraphenylporphyrin
Authors: ZHOU Xian‐Tai , JI Hong‐Bing , YUAN Qiu‐Lan , XU Jian‐Chang , PEI Li‐Xia , WANG Le‐Fu 
Published: June 2008

AbstractLow amount of manganese meso‐tetraphenyl porphyrin [Mn(TPP)] was used for highly efficient selective oxidation of sulfide to sulfone by hydrogen peroxide at room temperature. Sulfones were produced directly with yields generally around 90% while the catalyst concentration was only 4×10−5 mol·L−1. In a large‐scale experiment of thioanisole oxidation, the isolated yield of sulfone (87%) was obtained and the turnover number (TON) reached up to 8×106, which is the highest TON for the oxidation systems of sulfide to sulfone catalyzed by metalloporphyrins.
Selective and Efficient Oxidation of Aldehydes to Their Corresponding Carboxylic Acids Using H2O2/HCl in the Presence of Hydroxylamine Hydrochloride
Authors: BAHRAMI Kiumars , KHODAEI Mohammad Mehdi , KAMALI Shahab 
Published: June 2008

AbstractA wide variety of aldehydes were efficiently converted to their corresponding carboxylic acids in high yields using H2O2/HCl in the presence of hydroxylamine hydrochloride. In addition, selective oxidation of aldehydes in the presence of other functional groups such as hydroxyl group, carbon‐carbon double bond and other heteroatoms can be considered a noteworthy advantage of this method.
Crystal Structure and Properties of the Carboxylic Acid Derivatives of Schizonpeta mulifida (L.) Briq.
Authors: LIU Ju‐Tao , YU Ji‐Cheng , JIANG Hui‐Ming , ZHANG Li‐Ying , ZHAO Xiao‐Jing , FAN Sheng‐Di 
Published: June 2008

AbstractThe chemical constituents of the carboxylic acid derivatives from the ear of Schizonepeta were investigated. 1H and 13C NMR chemical shifts of the carboxylic acid derivatives were accurately assigned. Two carboxylic acid derivative constituents were separated by a silica gel column. The structures were elucidated by the physical and chemical properties, IR, 1H NMR, 13C NMR, MALDI‐TDF‐MS and X‐ray single crystal diffractometry. They were identified as 3‐imino‐N‐(α‐imidoethylamino)butyrolactam and neononane tetracid, respectively. The antitumoral activity on liver tumor cells SMMC‐7721 was determined in vitro. The experimental results showed that the former was better than the latter, and with increasing the concentration of the former the inhibitory activity was increased.
Synthesis and Biological Activities of Alkyl Substituted Triazolethione Schiff Base
Authors: SUN Xiao‐Hong , TAO Yan , LIU Yuan‐Fa , CHEN Bang , JIA Ying‐Qi , YANG Jian‐Wu 
Published: June 2008

AbstractEight Schiff bases have been synthesized using 3‐alkyl‐4‐amino‐1,2,4‐triazole‐5‐thione and substituted benzaldehyde as starting materials. The structures of the compounds have been confirmed by 1H NMR, IR and elemental analysis and their biological activities to five vegetable pathogens have been tested. The results showed that they exhibited good fungicidal activities.
Synthesis and Demulsibility of the Terpolymer Demulsifier of Acryl Resin
Authors: KANG Wan‐Li , MENG Ling‐Wei , ZHANG Hong‐Yan , LIU Shu‐Ren 
Published: June 2008

AbstractTerpolymer demulsifier of acryl resin has been synthesized through solution polymerization with water as a dissolvent, potassium persulfate as an initiator and the monomers of methyl methacrylate, butyl acrylate and acrylic acid as starting materials. The effects of the reaction temperature, dripping time, the amount of monomers and initiator on the dehydration rate of the demulsifier were investigated by an orthogonal experiment. It shows that the stronger influence on the dehydration rate among six factors is reaction temperature, dripping time, and amount of catalyst, while monomer has weak influence. The performance of the demulsifier was evaluated under different demulsification time, temperatures and concentrations of the screened demulsifiers. The result shows that the dehydration rate of the demulsifier can reach over 67%, which is better than that by the emulsion polymerization way.
2‐(1H‐Benzotriazole‐1‐yl)‐1,1,3,3‐Tetramethyluronium Tetrafluoro Borate (TBTU) as an Efficient Coupling Reagent for the Esterification of Carboxylic acids with Alcohols and Phenols at Room Temperature
Authors: BALALAIE Saeed , MAHDIDOUST Maryam , ESHAGHI‐NAJAFABADI Rasoul 
Published: June 2008

AbstractEsterification of carboxylic acids with alcohols and phenols by using 2‐(1H‐benzotriazole‐1‐yl)‐1,1,3,3‐tetramethyluronium tetrafluoroborate (TBTU) in the presence of triethylamine as a base proceeded smoothly under mild conditions to afford the corresponding esters in good to high yields in acetonitrile at room temperature.
Synthesis and Luminescent Properties of Two New Triphenylamine‐based Compounds with Hetero‐cyclic Ring as Conjugation Bridge
Authors: LI Qian‐Qian , DI Chong‐An , YU Gui , LIU Yun‐Qi , LI Zhen , QIN Jin‐Gui 
Published: June 2008

AbstractTwo new "D‐π‐D" type triphenylamine‐based compounds with a heterocyclic ring, furan or thiophene, as a conjugation bridge were synthesized through a normal Wittig reaction which exhibited good thermal stability and strong luminescence. The preliminary light‐emitting diode results indicate that they are promising candidates for the practical application.
A New Fluorescent Chemosensor for Cu2+ Based on 1,2,3,4,5,6,7,8,9,10‐Decahydroacridine‐1,8‐dione Fluorophore
Authors: LI Lin‐Bo , JI Shun‐Jun , LIU Yu 
Published: June 2008

AbstractA new chemosensor for Cu2+ was synthesized based on 1,2,3,4,5,6,7,8,9,10‐decahydroacridine‐1,8‐dione dyes, which exhibited an obvious fluorescent selectivity to the sensing of Cu2+ ions over other cations, such as Na+, K+, Ca2+, Cd2+, Co2+, Hg2+, Mg2+, Mn2+, Ni2+, Zn2+, Ag+ and Pb2+. Moreover, it presented a fluorescent switch function when EDTA was added to the compound‐Cu2+ complex in examined systems.
Structures, Vibrational Spectra, and Relative Energetics of CH3COIO3 Isomers
Authors: GE Mao‐Fa , MA Chun‐Ping 
Published: June 2008

Abstract The structures, vibrational spectra, relative energetics, and enthalpies of formation of CH3COIO3 isomers have been investigated with B3LYP, B3P86 and B3PW91 methods in conjugation with the 6‐31+G(d), 6‐311+G(d,p) and 6‐311++G(3df,3pd) basis sets. The CH3COOIO2 structure was found to be the most stable form among the isomers with an estimated enthalpy of formation of −314.6 kJ·mol−1. The enthalpies of formation for CH3COOOOI, CH3COOOIO and CH3COIO3 are −180.7, −184.9 and −50.6 kJ·mol−1, respectively. The implication of the formation of CH3COIO3 isomers from the atmospheric cross‐reactions of the acetylperoxy (CH3COO2) and iodine monoxide (IO) radicals was examined and the possible dissociation products of the most likely CH3COIO3 isomers were determined.
Theoretical and Experimental Study of Complex Ions from Reactions of Al+ (Cu+) with Amine Molecules
Authors: HU Zheng‐Fa , LUO Li , HU Yi‐Hua 
Published: June 2008

AbstractThe gas phase reactions of metal ions (Al+, Cu+) with amine molecules [CH3NH2=MA, (CH3)2NH=DMA] were investigated using a laser ablation‐molecular beam method. The directly associated product complex ions,Al+‐MA and Al+‐DMA, and the dehydrogenation product ions, Cu+(CH2NH) and Cu+(C2H5N), as well as hydrated ion Cu+(NC2H5·H2O), have been obtained and recorded from the reactions of the metal ions and organic amine molecules, and density functional theory (B3LYP) calculations have been performed to reveal the optimized geometry, energetics, and reaction mechanism of the title reactions with basis set 6‐311+G(d,p) adopted.
Ab initio and DFT Study of the Structural Properties and Thermochemistry of CH3S(O)2OONO2 Atmospheric Molecule and CH3S(O)2OO· Radical
Authors: GE Mao‐Fa , DU Lin , MA Yan‐Ping , HE Sheng‐Gui 
Published: June 2008

AbstractThe conformational properties of methanesulfonyl peroxynitrate, CH3S(O)2OONO2 (MSPN), and its radical decomposition products CH3S(O)2OO· and CH3S(O)2O· were studied by ab initio and density functional methods. The dihedral angle around the S–O and the O–O single bond are calculated to be −70.5° and −97.8° (B3LYP/6‐311++G(3df,3pd)), respectively. The principal unimolecular dissociation pathways for MSPN were studied using complete basis set (CBS) methods. The reaction enthalpies for the channels CH3S(O)2OONO2→ CH3S(O)2OO·+NO2 and CH3S(O)2OONO2→CH3S(O)2O·+NO3 were computed to be 111.0 and 140.9 kJ/mol, respectively. The enthalpies of formation at 298 K for MSPN and CH3S(O)2OO radical were predicted to be −358.2 and −281.3 kJ/mol, respectively.
Facile Biocatalytic Access to 9‐Fluorenylmethyl Polyglycosides: Evaluation of Antiviral Activity on Immunocompetent Cells
Authors: Tramice Annabella , Arena Adriana , De Gregorio Ambra , Ottanà Rosaria , Maccari Rosanna , Pavone Bernadette , Arena Nicoletta , Iannello Daniela , Vigorita Maria Gabriella , Trincone Antonio 
Published: June 2008

AbstractThe biological activities of a series of mono‐ and oligosaccharides (β‐xylosides and α‐glucosides) of 9‐fluorenylmethanol were investigated together with mono‐β‐galactoside and β‐glucoside of this aglycone, produced by biocatalytic routes. By using marine glycoside hydrolases and inexpensive donors such as maltose or xylan, access to mono‐α‐glucoside or mono‐β‐xyloside of 9‐fluorenylmethanol was obtained. Additionally, interesting polyglycoside derivatives were isolated. Biological testing indicated that in vitro treatment with these carbohydrate derivatives may influence the balance of cytokines in the environment of human peripheral blood mononuclear cells (PBMC), restricting the harmful effect of herpes simplex type 2 replication. In fact, these carbohydrate derivatives tested in WISH cells did not show any significant antiviral activity.
Ambipolar Transport in the Smectic E Phase of 2‐Propyl‐5′′‐Hexynylterthiophene Derivative over a Wide Temperature Range
Authors: Funahashi Masahiro , Zhang Fapei , Tamaoki Nobuyuki , Hanna Jun‐ichi 
Published: June 2008

Abstract5‐Hexyl‐5′′‐hexynyl‐2,2′:5′,2′′‐terthiophene exhibits the smectic E phase below 200 °C and does not crystallize when it is cooled to −100 °C. Between 200 and −100 °C, non‐dispersive transport is observed for holes and electrons with time‐of‐flight spectroscopy. Over the entire temperature range, the electron mobility is approximately twice as high as that of the hole. The hole and electron transport characteristics in the smectic phase below 0 °C are explained by the Gaussian disorder model, which was proposed for amorphous organic semiconductors. The disorder parameters, σ and Σ, are almost the same for holes and electrons. However, the pre‐exponential parameter μ0 for the electron is twice as large as that for the hole, which can be attributed to the difference in the extension of the LUMO of the molecules. The energetic disorder σ is primarily determined by the disorder in the orientation of the permanent dipoles of liquid crystal molecules.
Highly Accurate CCSD(T) and DFT–SAPT Stabilization Energies of H‐Bonded and Stacked Structures of the Uracil Dimer
Authors: Pitoňák Michal , Riley Kevin E. , Neogrády Pavel , Hobza Pavel 
Published: June 2008

AbstractThe CCSD(T) interaction energies for the H‐bonded and stacked structures of the uracil dimer are determined at the aug‐cc‐pVDZ and aug‐cc‐pVTZ levels. On the basis of these calculations we can construct the CCSD(T) interaction energies at the complete basis set (CBS) limit. The most accurate energies, based either on direct extrapolation of the CCSD(T) correlation energies obtained with the aug‐cc‐pVDZ and aug‐cc‐pVTZ basis sets or on the sum of extrapolated MP2 interaction energies (from aug‐cc‐pVTZ and aug‐cc‐pVQZ basis sets) and extrapolated ΔCCSD(T) correction terms [difference between CCSD(T) and MP2 interaction energies] differ only slightly, which demonstrates the reliability and robustness of both techniques. The latter values, which represent new standards for the H‐bonding and stacking structures of the uracil dimer, differ from the previously published data for the S22 set by a small amount. This suggests that interaction energies of the S22 set are generated with chemical accuracy. The most accurate CCSD(T)/CBS interaction energies are compared with interaction energies obtained from various computational procedures, namely the SCS–MP2 (SCS: spin‐component‐scaled), SCS(MI)–MP2 (MI: molecular interaction), MP3, dispersion‐augmented DFT (DFT–D), M06–2X, and DFT–SAPT (SAPT: symmetry‐adapted perturbation theory) methods. Among these techniques, the best results are obtained with the SCS(MI)–MP2 method. Remarkably good binding energies are also obtained with the DFT–SAPT method. Both DFT techniques tested yield similarly good interaction energies. The large magnitude of the stacking energy for the uracil dimer, compared to that of the benzene dimer, is explained by attractive electrostatic interactions present in the stacked uracil dimer. These interactions force both subsystems to approach each other and the dispersion energy benefits from a shorter intersystem separation.
The Crucial Role of the K+–Aluminium Oxide Interaction in K+‐Promoted Alumina‐ and Hydrotalcite‐Based Materials for CO2 Sorption at High Temperatures
Authors: Walspurger Stéphane , Boels Luciaan , Cobden Paul D. , Elzinga Gerard D. , Haije Wim G. , van den Brink Ruud W. 
Published: June 2008

AbstractCO2‐free hydrogen can be produced from coal gasification power plants by pre‐combustion decarbonisation and carbon dioxide capture. Potassium carbonate promoted hydrotalcite‐based and alumina‐based materials are cheap and excellent materials for high‐temperature (300–500 °C) adsorption of CO2, and particularly promising in the sorption‐enhanced water gas shift (SEWGS) reaction. Alkaline promotion significantly improves CO2 reversible sorption capacity at 300–500 °C for both materials. Hydrotalcites and promoted hydrotalcites, promoted magnesium oxide and promoted γ‐alumina were investigated by in situ analytical methods (IR spectroscopy, sorption experiments, X‐ray diffraction) to identify structural and surface rearrangements. All experimental results show that potassium ions actually strongly interact with aluminium oxide centres in the aluminium‐containing materials. This study unambiguously shows that potassium promotion of aluminium oxide centres in hydrotalcite generates basic sites which reversibly adsorb CO2 at 400 °C.
A Property‐Matched Water‐Soluble Analogue of the Benchmark Ligand PPh3
Authors: Ferreira Michel , Bricout Hervé , Hapiot Frédéric , Sayede Adlane , Tilloy Sébastien , Monflier Eric 
Published: June 2008

AbstractA series of sulfonated biphenylphosphanes were readily prepared from commercially available, inexpensive, and air‐stable organic compounds. Of these, the trisulfonated trisbiphenylphosphane can be considered as a true water‐soluble analogue of PPh3 as the cone angle and basicity of both phosphanes are very close and result in a similar coordination mode on palladium and rhodium complexes. The catalytic performance of the trisulfonated trisbiphenylphosphane was evaluated in the aqueous hydroformylation of 1‐decene and the Tsuji–Trost reaction.
Simultaneous Measurements of Ion Temperature by Segmented Tunnel and Katsumata Probe
Authors: Adámek J. , Kocan M. , Panek R. , Gunn J. P. , Martines E. , Stöckel J. , Ionita C. , Popa G. , Costin C. , Brotankova J. , Schrittwieser R. , Van Oost G. 
Published: June 2008

AbstractSimultaneous measurements of the ion temperature by the segmented tunnel and Katsumata probe in the CASTOR tokamak are reported. The segmented tunnel probe measures two ion saturation currents Iseg 1, Iseg 2 towards two segments of the tunnel. The axis of the tunnel is aligned with the total magnetic field. The value of the ratio of these two currents combined with the results of the PIC modeling provides the ion temperature. Design and experimental arrangement of the Katsumata probe enable us to measure the pure ion current by sweeping the applied voltage. The ion temperature is then estimated from the exponential part of the measured I – V characteristic. Simultaneous measurements of the ion temperature by the segmented tunnel and Katsumata probe agree within a few eV. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Plasma Boundary in a Magnetic Field
Authors: Allen J. E. 
Published: June 2008

AbstractPlasmas in the presence of a magnetic field can be divided into two categories, (a) those in which very small electron currents flow and the Boltzmann relation may be employed and (b) those in which there are appreciable electron currents and the use of the Boltzmann relation needs to be re‐examined. The present paper deals with the latter case. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computer Simulations of Probe Measurements in Argon Plasma: Effects of Finite Dimensions of the Probe
Authors: Bartoš P. , Hrach R. , Jelínek P. 
Published: June 2008

AbstractAlthough the computer performance improves markedly in recent years, pure particle simulations of effects caused by finite probe dimensions can be still hardly performed. Therefore, the hybrid modelling technique combining the advantages of both fluid and particle modelling techniques seems to be the best alternative for these studies. In our work there are presented possibilities provided by the fast and well multitask‐able computer model of hybrid type, which has been developed at our departments. The behaviour of low‐temperature electropositive plasma in the vicinity of probes with frequently used geometry shapes (planar, cylindrical and spherical) is discussed. The work is aimed both on the effects of finite probe dimensions and on the influence of the probe holder on sheath formation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Displacement of Charge and Conduction Current in Collisionless Planar Sheaths During Voltage Transients
Authors: Braithwaite N. St. J. , LauroTaroni L. , Haas F. A. , Turner M. M. 
Published: June 2008

AbstractThe relaxation of a planar space charge sheath has been modelled numerically to elucidate the dynamics of the process. A numerical model has been used to show that ion dynamics need to be included if the space charge in the sheath exceeds the amount of charge stored in the external circuit. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Fluid Model of Recombination and Ionization for Deduction of Flow Velocity in Magnetized Plasmas
Authors: Chung K.‐S. , Woo H.‐J. , Choi Y.‐S. , Lee M.‐J. 
Published: June 2008

AbstractFor the analysis of atomic processes such as recombination and ionization in the divertor plasmas, a new fluid model on the ion collection to a probing object in magnetized plasma is developed including electron‐ion recombination, molecular activated recombination and ionization. Density profiles and ratio of ion saturation currents are presented with ionization and recombination for the application to the Mach probe. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiple Floating Potentials of an Electron Emitting Electrode that Terminates a Bounded Plasma System with Hot Electrons
Authors: Gyergyek T. , Čerček M. , Jurčič‐Zlobec B. 
Published: June 2008

AbstractA fully kinetic one‐dimensional model of current collection by an electron emitting collector that limits a bounded plasma system that has been presented earlier [T. Gyergyek, M. Čerček, Czech J. Phys., 54, 431 (2004)] is further developed. Non‐zero drift velocities are included into the distribution functions of the hot and of the emitted electrons. Even relatively small drift velocities have large impact on the current collected by the collector. In the case of space charge limited electron emission from the collector the model predicts a triple floating potential of the collector for certain plasma parameters. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Uniform Description of Errors in Measurement and Evaluation of Langmuir Probe Characteristics by Means of Apparatus Functions
Authors: Hannemann M. 
Published: June 2008

AbstractThe evaluation of Langmur probe measurements frequently has to deal with distortions of the probe current or its derivatives which occur e.g. in rf‐discharges or in the differentiation of probe characteristics with electrical or numerical techniques. Using different methods it was shown that the distorted current or derivative is given by the convolution of the desired true function with an apparatus function. This contribution summarizes the treatment of the problem based on the fact that all distortions are caused by the superposition of additional voltages to the steady probe bias. This uniform behaviour allows a uniform treatment. In contrast to literature here separate apparatus functions for distortions caused by rf‐ oscillations are obtained. Examples of apparatus functions are shown for all kinds of distortions. Some applications of apparatus functions and a measuring example are given and a modified evaluation of the probe characteristic at incomplete rf‐compensation is proposed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
New Results on a Laser‐Heated Emissive Probe
Authors: Ionita C. , Balan P. , Windisch T. , Brandt C. , Grulke O. , Klinger T. , Schrittwieser R. 
Published: June 2008

AbstractDirect measurements of the plasma potential with high temporal and spatial resolution are only possible with special probes whose floating potential becomes equal to the plasma potential. One of these probes is the emissive probe which can be heated to electron emission. This leads to the effect that the plasma electron current towards the probe is compensated by an equal electron emission current flowing from the probe into the plasma which shifts the probe floating potential to the value of the plasma potential. While emissive probes are usually realized by heatable loops of wires of a refractory metal like tungsten or thoriated tungsten, we have developed various types of probes whose tip can be heated by an infrared laser beam. This offers several advantages like higher emission, longer lifetime and faster time response. Here we report on the latest development of a laser‐heated emissive probe and on measurements with it in a magnetized helicon plasma. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Three Dimensional Structure of Turbulence in the WEGA Stellarator
Authors: Marsen S. , Otte M. , Wagner F. 
Published: June 2008

AbstractLangmuir probes are used to study turbulent electrostatic fluctuations in the highly collisional plasmas of the WEGA stellarator. WEGA as a classical stellarator offers the opportunity to study fluctuations under various magnetic configurations. Two probe systems installed at WEGA give insight into the spatio‐temporal structure of fluctuations. A poloidal array of 13 probes is used to study the properties in poloidal direction. Toroidally resolved measurements give insight into the three‐dimensional structure of turbulence. To this end, a toroidally separated probe is placed on a field line intersecting the path of the poloidal array, as predicted by field line tracing calculations and verified experimentally by an electron gun. Probes are stationary biased to measure Isat and Φfl respectively. Fourier‐ and correlation‐analysis techniques are applied to the data. The paper gives a survey of the general characteristics of fluctuations in WEGA. The scaling of turbulent structures is studied by varying the ion mass and the magnetic field strength over a wide range and is found to depend on the drift parameter ρs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)