bluuebunny/crossref_metadata_2025_split huggingface dataset:
ChemInform Abstract: Construction of 3D Tissue‐Like Structure Using Functional Magnetite Nanoparticles
Authors: Ito Akira , Honda Hiroyuki , Kamihara Masamichi 
Published: May 2008

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Hole‐Transporting Hydrazones
Authors: Lygaitis Ramunas , Getautis Vytautas , Grazulevicius Juozas Vidas 
Published: May 2008

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Probing Invisible, Low‐Populated States of Protein Molecules by Relaxation Dispersion NMR Spectroscopy: An Application to Protein Folding
Authors: Korzhnev Dmitry M. , Kay Lewis E. 
Published: May 2008

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Paramagnetic Effects of Dioxygen in Solution NMR: Studies of Membrane Immersion Depth, Protein Topology, and Protein Interactions
Authors: Prosser R. S. , Evanics F. 
Published: May 2008

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: NMR Spectroscopy in the Liquid and Gas Phases
Authors: Davidson G. 
Published: May 2008

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: TROSY NMR for Studies of Large Biological Macromolecules in Solution
Authors: Fernandez Cesar , Wider Gerhard 
Published: May 2008

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Infrared Spectroscopy of Organometallic Ions in the Gas Phase: From Model to Real World Complexes
Authors: MacAleese Luke , Maitre Philippe 
Published: May 2008

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Theoretical Studies on the Electronic and Optical Properties of a New Class of Aromatic Oligomers and Polymers
Authors: LI Lei‐Jiao , FENG Ji‐Kang , REN Ai‐Min , TIAN Wei‐Quan 
Published: May 2008

AbstractThe purpose of this work is to provide an in‐depth interpretation of the optical and electronic properties of a series of aromatic oligomers and polymers, including [N‐(4‐(5‐(3‐(1,3,4‐oxadiazol‐2,5‐ylene)phenyl)‐1,3,4‐oxadiazol‐2‐ylene)phenyl)‐N‐(1,4‐phenylene)amine]n (NPPP)n and [N‐(4‐(5‐(3‐(1,3,4‐oxadiazol‐2,5‐ylene)phenyl)‐1,3,4‐oxa‐diazol‐2‐ylene)phenyl)‐N‐(1,4‐phenylene)naphthalene‐1‐amine]n (NPPN)n (n=1–4). These polymers and oligomers show great potential for application to organic light‐emitting diodes (OLEDs) as efficient blue emitters due to the tuning of the optical and electronic properties. The geometric and electronic structures of the oligomers in the ground state were investigated using density functional theory (DFT) and the ab initio HF, whereas the lowest singlet excited state of NPPP1 was optimized with ab initio configuration interaction singles (CIS). To assign the absorption and emission peaks observed in the experiment, the absorption and emission spectra of the ground and lowest singlet excited states were calculated with time‐dependent DFT (TD‐DFT) and Zerner's independent neglect of differential overlap (ZINDO). All DFT calculations were performed using the B3LYP functional and the 6‐31G basis set. The results show that the HOMO, LUMO, energy gaps, ionization potentials, and electron affinities for these polymers are affected by increasing the conjugated chain, which favors the hole and electron injection into OLED. The trend of the variation of ΔH‐L and the lowest excitation energies with 1/n, and the electronic structure and optical properties of these polymers were extrapolated and analyzed. The absorption spectra exhibit red shifts to some extent [the absorption spectra: 359.47 (NPPP1)<370.84 (NPPP2)<373.84 (NPPP3)<375.33 nm (NPPP4); 361.14 (NPPN1)<370.34 (NPPN2)<373.39 (NPPN3)<374.62 nm (NPPN4)]. Our calculated spectra agree well with the experimental findings where available, showing small but systematic deviations.
Nafion‐Coated Bismuth Film Electrodes for the Determination of Trace Lead and Cadmium in Herbal Medicines by Anodic Stripping Voltammetry
Authors: XU He , ZENG Li‐Ping , XING Su‐Jie , XIAN Yue‐Zhong , JIN Li‐Tong 
Published: May 2008

AbstractA novel analytical procedure for the determination of Pb(II) and Cd(II) in herbal medicines by differential pulse anodic stripping voltammetry (DPASV) on Nafion‐coated bismuth film electrode (NCBFE) was proposed and experimentally validated. Various experimental parameters, which influenced the response of the NCBFE to these metals in real samples, were optimized. The results showed that there were well‐defined peaks of Pb and Cd in herb samples at deposition potential of −1.2 V and deposition time of 300 s. The analytical performance of the NCBFE was evaluated in the presence of dissolved oxygen, with the determination limits of 0.35 µg·L−1 for Pb and 0.72 µg·L−1 for Cd and recoveries of 87.8% –105.4% for Pb and 89.5% –108.5% for Cd obtained from different samples. The Pb and Cd concentrations in the studied samples have been also determined by graphite furnace atomic absorption spectrometry (GFAAS), suggesting that there was a satisfactory agreement between the two techniques, with relative errors lower than 6.5% in all cases. The great advantages of the proposed method over the spectroscopic method were characterized by its simplicity, selectivity and short analysis time, simultaneous analysis of different metals and cost‐efficiency.
Ab initio Study of Electronic Structure and Properties in Crystalline 1,1,3,3,5,5‐Hexaazidocyclotriphosphazene
Authors: HUANG Hui‐Sheng , ZHANG Jian‐Guo , ZHANG Tong‐Lai , YANG Li , ZHENG Hui‐Hui 
Published: May 2008

AbstractThe banding and electronic structures of crystalline 1,1,3,3,5,5‐hexaazidocyclotriphosphazene (P3N21) have been investigated at DFT‐B3LYP/6‐31G(d) level. Relaxed crystal structure compares well with experimental data. The energy gap is 5.57 eV, indicating that P3N21 is an insulator. The frontier orbital is mainly formed by atomic orbitals of azido group, so it is the most reactive part of the molecule. The intermolecular interaction is strong along the direction that is nearly perpendicular to the phosphazene ring. The distribution of electrostatic potential is quite uneven, so P3N21 has a very high impact sensitivity. The point charge electrostatic potential is very high between the azido groups of the neighboring molecules, which indicates that the crystal lattice in this position may easily be broken and becomes the explosion center when P3N21 is impacted. The overlap populations of P–Nα bonds are much less than those of other bonds, therefore the P–Nα bonds first rupture by external stimuli, which agrees well with the experimental study of mass spectrum.
Effects of the Interaction of Rifamycin SV with Serum Albumins on the Resonance Rayleigh Scattering Spectra and Their Analytical Application
Authors: YANG Ji‐Dong , CAO Tuan‐Wu , LIU Zhong‐Fang , KONG Ling , LIU Shao‐Pu 
Published: May 2008

AbstractIn pH 4.5–4.8 Britton‐Robinson buffer solution, rifamycin SV (i.e. rifamycin sodium) can react with serum albumin such as human serum albumin (HSA) and bovine serum albumin (BSA) to form macromolecular complexes by electrostatic attraction and hydrophobic force. As a result, the resonance Rayleigh scattering (RRS) of the drug was enhanced remarkably and the RRS peaks were at 374 and 552 nm. The enhancement of RRS (ΔI) is directly proportional to the concentration of HSA or BSA. The linear ranges and the detection limits are 0.03–6.0 µg/mL and 9.0 ng/mL for HSA, and 0.01–8.0 µg/mL and 2.0 ng/mL for BSA, respectively. In this work, a sensitive, selective, simple and fast method for the determination of trace amounts of serum albumin by RRS technique has been developed, which was applied to the determination of serum albumin in the synthesized samples and human urine samples with satisfactory results.
L‐Proline‐based Phosphamides as a New Kind of Organocatalyst for Asymmetric Direct Aldol Reactions
Authors: YU Guo , GE Ze‐Mei , CHENG Tie‐Ming , LI Run‐Tao 
Published: May 2008

AbstractFour L‐proline‐based phosphamides were designed and synthesized as a new kind of organocatalyst. Their catalytic activities for asymmetric direct aldol reactions were evaluated. Among them, 3a with 10 mol% catalyst loading afforded moderate to good yields and up to 99% ee.
Synthesis and Bioactivity of Novel N,N′‐Diacylhydrazine Derivatives Containing Furan(I)
Authors: CUI Zi‐Ning , HUANG Juan , LI Ying , LING Yun , YANG Xin‐Ling , CHEN Fu‐Heng 
Published: May 2008

AbstractThe furan ring system possesses electron‐rich properties and exhibits various biological activities, which was introduced into diacylhydrazine to create novel leading compounds that may serve as improved pesticides and pharmaceuticals. A series of novel diacylhydrazine derivatives containing a furan ring were synthesized by the reaction of 5‐fluorophenyl‐2‐furoyl chloride with substituted benzoylhydrazide in anhydrous dichloromethane under reflux. The structures of the resultant compounds were confirmed by IR, 1H NMR, MS and elemental analysis. Insecticidal and anti‐tumor activities of these new compounds were evaluated.
Kinetics of Heterogeneous Solvent‐free Liquid Phase Oxidation of Alcohol Using ZrO2 Catalyst with Molecular Oxygen
Authors: ILYAS Mohammad , SADIQ Mohammad 
Published: May 2008

AbstractClean liquid phase solvent‐free oxidation of alcohol to aldehyde/ketone using ZrO2 catalyst with molecular oxygen has been studied. Monoclinic phase ZrO2 has been synthesized and characterized by XRD, SEM, EDX and surface and pore size analyses. Oxidation of alcohol was carried out in a typical batch reactor at different speed of agitation (150–1200 r/min), temperature (373–413 K), catalyst loading (50–300 mg) and partial pressure of oxygen (12–101 kPa). These parameters influence alcohol conversion as well as selectivity. A handy touch of kinetics was given to the experimental data and apparent activation energy was calculated.
Hydrothermal Synthesis of Two High‐dimensional Architectures Based on Bridging Ligand Pyridine‐2,3‐dicarboxylic Acid
Authors: DU Lin , FANG Rui‐Bin , ZHAO Qi‐Hua 
Published: May 2008

AbstractTwo novel metal‐organic coordination polymers [Zn2(PDC)2·H2O]n (1) and [Zn2La2(OH)(NO3)(PDC)4‐ (H2O)6·2H2O]n (2) (PDC��pyridine‐2,3‐dicarboxylic acid) have been synthesized by hydrothermal pretreatment and cooling‐down crystallization. X‐ray diffraction analyses reveal that they posses the 3D frameworks. Frame work 1 has been accomplished by using building blocks Zn‐PDC with beautiful undulances. Frame work 2 is a new 3d‐4f heterometallic polymer with a distinctive mono‐ and dinuclear mixed one sinusoidal‐like wave viewed along the b axis.
A Theoretical Investigation on the Reaction Mechanism of the C8H10+· Side‐Chain Decomposition Processes
Authors: CHENG Xue‐Li , ZHAO Yan‐Yun , LI Feng 
Published: May 2008

AbstractThe dissociation of ethylbenzene cation C8H10+· served as a prototype to investigate the decompasition mechanisms of alkylbenzene cations. The reactions of C8H10+· decomposition reaction system have been studied extensively at the B3LYP/6‐311++G∗︁ ∗︁ level with Gaussion 98 package. The chain reaction of C8H10+· dissociation is initiated by C–H bond rupture. All reaction channels were fully investigated with the vibrational mode analysis to confirm the transition states and reveal the reaction mechanism. The energetically most favorable pathway is C8H10+·→TS4→P2+H· and the channel leading to C8H10+· and C2H4 is also competitive.
Directing the Growth of Semiconductor Nanocrystals in Aqueous Solution: Role of Electrostatics
Authors: Zhang Hao , Liu Yi , Wang Chunlei , Zhang Junhu , Sun Haizhu , Li Minjie , Yang Bai 
Published: May 2008

AbstractIn this study, we demonstrate a new insight into the growth stage of aqueous semiconductor nanocrystals (NCs); namely, that the experimental variable‐dependent growth rate and photoluminescence quantum yields (PLQYs) are understandable according to electrostatics. In this context, the aqueous NCs possess (from core outwards) an inorganic core, ligand layer, adsorbed layer, and a diffuse layer. The presence of an electric double‐layer not only makes the NCs dispersible in the colloidal solution, but also governs the migration of monomers and monomer adsorption on the NC surface. To maintain NC growth, monomers need to migrate through the double‐layer. Consequently, the nature of the diffuse layer influences the ability of monomer diffusion and hence the growth rate of NCs. Systematic studies reveal that the experimental variables, including precursor concentrations, pH of the solution, additional NaCl concentrations, ratio of Cd to ligand, and the nature of the ligands significantly govern the nature of the NC electric double‐layer. The experimental variables, which reduce the thickness of the diffuse layer, benefit from monomer diffusion and a rapid growth of NCs. However, on the other hand, the diffuse layer also presents a charge‐selective transfer of Cd monomers. The neutral monomers, such as the complex of Cd2+ and 3‐mercaptopropionic acid (MPA) with 1:1 molar ratio [Cd(MPA)], migrate through the diffuse layer more easily than the charged ones [Cd(MPA)22− or Cd(MPA)34−], thus facilitating the growth of NCs. The nature of the adsorbed layer inside the diffuse layer, defined as the assumed interface of solid NCs and the liquid environment, also affects the growth rate and especially the PLQYs of NCs through the adsorption and coalescence of monomers on this interface. Strong interaction between the adsorbed layer and Cd monomers provides the opportunity to accelerate NC growth and to obtain NCs with high PLQYs.
Multipactor Breakdown Prediction in a Rectangular Waveguide: Statistical Theory and Simulation Results
Authors: Sazontov A. G. , Sazontov V. A. , Vdovicheva N. K. 
Published: May 2008

AbstractStatistical theory of the initial study of the multipactor discharge in a rectangular waveguide is constructed. The recurrent relation between the emission phase and position distributions is derived taking into account the velocity spread of secondary electrons. A general integral equation allowing prediction of the threshold value of the secondary yield (above which electron multipaction occurs) is formulated. It has been found that the presence of directional anisotropy can significantly alter the multipacting discharge cutoff conditions in comparison with isotropic emission. It has been established that the combined action of tangential velocity components and magnetic field leads to an increase of the threshold of multipactor growth. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
“Hidden” Spin–Spin Interactions in Complex Multispin Solids
Authors: Gorelik Elena V. , Ovcharenko Victor I. , Baumgarten Martin 
Published: May 2008

AbstractA detailed analysis of the electronic structure and magnetic properties of a heterospin network based on a Cu(hfac)2 complex with a nitronyl nitroxide biradical using the broken‐symmetry density functional theory approach is reported. An extremely complex set of exchange parameters was revealed that cannot be obtained from the data of magnetochemical experiments alone. The compensating contributions from various exchange clusters show themselves in a sophisticated combination, and would be “hidden” without an in‐depth quantum chemical investigation. For this purpose the extended network was subdivided into the dominating spin clusters bridged by the organic biradical spacer and each spin system was checked for a consistency of the spin couplings. Fairly large positive and negative exchange couplings in the strongly coupled clusters were found to cancel each other out. Furthermore, the detailed substructure analysis revealed that even in a linearly aligned spin system the next‐nearest‐neighbor interactions can be of the utmost importance and of similar size to that of the direct‐neighbor exchange. Calculated exchange interaction parameters were employed to model the temperature dependence of the effective magnetic moment for the heterospin system under study. The use of PBE0 estimates of exchange interaction parameters yielded a μeff(T) dependence that was in good agreement with the experimental data, which enabled the data to be used as a starting point in the fitting procedure leading to the physical meaningful results.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Lanthanide‐Based Conjugates as Polyvalent Probes for Biological Labeling
Authors: Claudel‐Gillet Stéphanie , Steibel Jérôme , Weibel Nicolas , Chauvin Thomas , Port Marc , Raynal Isabelle , Toth Eva , Ziessel Raymond F. , Charbonnière Loïc J. 
Published: May 2008

AbstractA series of lanthanide complexes of [LnL(H2O)] composition, suitable for biological labeling has been studied, in which L is a strongly chelating ligand containing chromophoric bipyridylcarboxylate units and Ln = Sm, Eu, Gd, Tb, and Dy. For the Gd complex, a combined 17O NMR and 1H NMRD study has been performed. The water exchange rate obtained, kex298 = (5.2 ± 0.6) × 106 s–1, is slightly higher than those for [Gd(dota)(H2O)]– or [Gd(dtpa)(H2O)]2–. Transformation of the uncoordinated carboxylate function of the ligand into an activated ester ensures covalent linking of the complex to bovine serum albumine (BSA). The relaxivity properties of the Gd complex labeled on BSA revealed a limited increase of both longitudinal and transversal relaxivities. This can be related to the partial replacement of the inner‐sphere water molecules by coordinating functions of the protein. Additionally, the Sm and Dy complexes are described and chemically characterized. Their photophysical properties were investigated by means of absorption, steady‐state and time‐resolved spectroscopy, evidencing efficient photosensitization of the lanthanide emission by ligand excitation (antenna effect). Luminescence lifetime measurements confirmed the presence of a water molecule in the first coordination sphere that partly explained the relatively poor luminescence properties of the Dy and Sm complexes in aqueous solutions. The spectroscopic properties of the series of complexes are questioned in terms of time‐resolved acquisition techniques. Finally, their availability for use in time‐resolved luminescence microscopy is demonstrated by staining experiments of rat brain slices, where the complex showed enhanced localization in some hydrophilic regions of the blood–brain barrier (BBB).(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Tetra‐tert‐butyltrioxabicyclo[3.3.1]nonadienedicarboxylic Acid: Optical Resolution, Absolute Configuration and Application in Chiral Discrimination
Authors: Kremsner Jennifer , Wallfisch Bianca C. , Belaj Ferdinand , Uray Georg , Kappe C. Oliver , Wentrup Curt , Kollenz Gert 
Published: May 2008

AbstractThe enantiopure bridged bis‐dioxine 4, a dissymmetric dicarboxylic acid exhibiting axial chirality, can easily be synthesized and serve as host for separating and/or transporting chiral guest molecules. Racemic 4 gives with (R)‐ and (S)‐1‐phenylethylamine the corresponding pure diastereomeric salts 7 and 8. The absolut configuration of the diacid 4 in the diastereomeric salt 7 containing (R)‐1‐phenylethylamine was confirmed to be R by X‐ray crystal structure analysis, which also confirmed its concave nature. Release of the acid‐sensitive pure enantiomers (R)‐4 as well as (S)‐4 was achieved conveniently by use of dry flash‐chromatography on silica. The CD spectrum shows a positive Cotton effect of the (S)‐enantiomer at 206 nm. The enantiomeric purity was proved by 1H NMR discrimination of the diastereomeric salts with (R,R)‐1,2‐bis(4‐methoxyphenyl)ethane‐1,2‐diamine as the base. The dicarboxylic acid (R)‐4 can be used as chiral auxiliary as demonstrated by the difficult resolution of racemicN,N′‐di‐tert‐butyl‐1,2‐bis(4‐methoxyphenyl)ethane‐1,2‐diamine 9.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis of Natural Product Derivatives Containing 2,4‐Concatenated Oxazoles
Authors: Hernández Delia , Riego Estela , Albericio Fernando , Álvarez Mercedes 
Published: May 2008

AbstractHerein is described the synthesis of several oxazole‐containing derivatives of IB‐01211. The macrocyclization reaction of peptide 14 containing a concatenated triazole was successful and afforded 3 by amide bond formation. However, for those compounds containing quaterazoles or quinqueazoles, the oxazole ring had to be formed during macrocyclization. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Electrochemical Preparation of Brilliant‐Blue‐Modified Poly(diallyldimethylammonium Chloride) and Nafion‐Coated Glassy Carbon Electrodes and Their Electrocatalytic Behavior Towards Oxygen and L‐Cysteine
Authors: Chen Shen‐Ming , Chen Ji‐Yan , Thangamuthu R. 
Published: May 2008

AbstractBrilliant blue FCF‐modified glassy carbon electrodes have been prepared by cycling the Nafion (or poly(diallyldimethylammonium chloride) (PDDAC)) coated electrodes repeatedly 15 cycles in brilliant blue FCF (BB FCF) dye solution. The BB FCF molecules are incorporated into Nafion coating by cycling the film‐covered electrode between +0.3 to 1.2 V (vs. Ag/AgCl) in pH 1.5 BB FCF solution while PDDAC‐coated electrode cycled between 0 to −1.0 V (vs. Ag/AgCl) in pH 6.5 BB FCF solution to immobilize the dye. Electrostatic interaction between dye molecule and PDDAC was predominant in PDDAC coating whereas immobilization of dye in Nafion film attributed to the combined effect of electrostatic and hydrophobic interactions. The voltammetric features of BB FCF‐modified electrodes resemble that of surface‐confined redox couples. The peak potentials of BB FCF‐incorporated PDDAC‐coated electrode were shifted to more positive potential region with decreasing pH of contacting solution. BB FCF‐modified electrodes showed electrocatalytic activity towards reduction of oxygen and oxidation of L‐cysteine with significant decease of overvoltage compared to unmodified electrode. The BB FCF‐modified Nafion‐coated electrode was tested for its analytical applications toward determination of L‐cysteine. The linear range of calibration plot at BB FCF‐modified Nafion‐coated electrode is 10 to 100 μM, which coincides with L‐cysteine levels in biological fluids. Sensitivity and detection limit of the electrode are 111 nA μM−1 and 0.5 μM, respectively.