bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and Application of Linked‐BINOL Chiral Ligands in Bifunctional Asymmetric Catalysis
Authors: Shibasaki Masakatsu , Matsunaga Shigeki 
Published: June 2006

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, please click on HTML or PDF.
Photochemistry from First Principles and Direct Dynamics
Authors: Toniolo A. , Levine Benjamin G. , Thompson Alexis L. , Quenneville Jason , Ben‐Nun M. , Owens Jane M. , Olsen Seth , Manohar Leslie , Martinez Todd J. 
Published: June 2006

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, please click on HTML or PDF.
Toward an Understanding of the Factors Responsible for the 1,2‐Migration of Alkyl Groups in Borate Complexes
Authors: Aggarwal Varinder K. , Fang Guang Yu , Ginesta Xavier , Howells Dean M. , Zaja Mirko 
Published: June 2006

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, please click on HTML or PDF.
Theoretical Studies on Proton Transfer Reactions of 8‐Hydroxyquinoline Monomers and Dimers
Authors: Zhao Ji‐Yang , Zhou Zi‐Yan , Su Zhong‐Min , Xie Yu‐Zhong , Sun Guang‐Yan , Wu Xue 
Published: June 2006

AbstractDensity functional theory (DFT) of quantum chemistry method was employed to investigate proton transfer reactions of 8‐hydroxyquinoline (8‐HQ) monomers and dimers. By studying the potential energy curves of the isomerization, the most possible reaction pathway was found. The total energy of 8‐hydroxyquinoline was lower than that of quinolin‐8(1H)‐one, whereas the order was reversed in dimers. The findings explained the contrary experimental phenomena. The minimum reaction barrier of intramolecular proton transfer was 47.3 kJ/mol while that in dimer was only 25.7 kJ/mol. Hence it is obvious that proton transfer reactions of 8‐HQ monomer have a considerable rate but it is easier to proceed for 8‐HQ dimer than monomers. It implied that the hydrogen bond played an important role in depressing the activation energy of reaction. The mechanism of the tautomerization was discussed on the basis of theoretical results.
Structure and Stability of (HBNH)n Clusters
Authors: Wang Hong , Wu Hai‐Shun , Jia Jian‐Feng 
Published: June 2006

AbstractStructures and thermodynamic properties of the imidoboranes (HBNH)n (n=1–16) have been investigated theoretically at the B3LYP/6‐31G* level of theory. Needle‐shaped oligomers that violate the isolated square rule were found to be more stable than cage isomers. The needle‐shaped oligomer with n=16 was predicted to be exceptionally stable at low temperature, hexamer and octamer clusters dominated the gas phase at higher temperature. The highest oligomerization degree of the spontaneous cluster fomation has been estimated. It was concluded that generation of the gas phase (HBNH)n clusters with oligomerization degree n≧24 was viable, making these species possible intermediates involved in the gas phase generation of BN nanoparticles.
Hydrothermal Synthesis and Thermal Analyses of an Infinite Three‐dimensional Coordination Polymer Based on Formic Acid:[Zn(HCOO)2(H2O)2]∞
Authors: Guo Jin‐Yu , Zhang Tong‐Lai , Zhang Jian‐Guo 
Published: June 2006

AbstractThe coordination polymer [Zn(HCOO)2(H2O)2]∞ has been synthesized using hydrothermal method and characterized by X‐ray single crystal diffraction, elemental analysis, FTIR spectroscopy and TG‐DTG analyses. The coordination polymer crystallizes in monoclinic, P21/c space group with crystal parameters of a=0.8688(1) nm, b=0.7143(6) nm, c=0.9305(2) nm, β=97.61(5)°, V=0.5724(2) nm3, Z=4, μ(Mo Kα) =42.50 cm−1. The polymer features with two kinds of zinc centers:one is hexa‐coordinated by four water ligands, two oxygen atoms of two formates and the other is coordinated by six oxygen atoms of six formates. By the formates as space linkers, three‐dimensional frameworks were formed. Based on thermal analyses, thermal decomposition mechanisms were predicted that at the first step the polymer lost two coordination water molecules and at the second step lost two formates companied by the formation of some kinds of materials.
Determination of Pb(II) and Cu(II) by Electrothermal Atomic Absorption Spectrometry after Preconcentration by a Schiff Base Adsorbed on Surfactant Coated Alumina
Authors: Saber tehrani Mohammad , Rastegar Faramarz , Parchehbaf Ayob , Khatamian Masoomeh 
Published: June 2006

Abstract1,2‐Bis(salicylidenamino)ethane loaded onto sodium dodecyl sulfate‐coated alumina was used as a new chelating sorbent for the preconcentration of traces of Pb(II) and Cu(II) prior to atomic absorption spectrometric determination. The influence of pH, flow rates of sample and eluent solutions, and foreign ions on the recovery of Pb(II) and Cu(II) by this sorbent has been studied. The retained ions were eluted with 4 mol·L nitric acid and determined by electrothermal atomic absorption spectrometry (ETAAS). The data of limit of detection (3σ) for Pb(II) and Cu(II) were found to be 8.57 and 2.69 ng·L−1 respectively, while the enrichment factor for both ions was 100. The proposed method was successfully applied to determination of lead and copper in different water samples.
Conjugate Additions of Secondary Amines and Water to Allenyl Perfluoroalkyl Sulfones
Authors: Wang Xiao‐Jin , Lin Yun , Liu Jin‐Tao 
Published: June 2006

AbstractPreparation of allenyl perfluoroalkyl sulfones from perfluoroalkyl sulfinyl chlorides and their reactions with secondary amines and water were studied. At room temperature secondary amines reacted readily with allenyl perfluoroalkyl sulfones to give the corresponding enamine adducts, which underwent rearrangement to afford conjugate enamines in refluxing toluene. Good diastereoslectivities were observed in the addition of diethylamine to γ‐ethyl‐γ‐methylallenyl perfluoroalkyl sulfones. In refluxing acetonitrile, water could also undergo the similar addition with allenyl perfluoroalkyl sulfones.
One Pot Reduction of Imines Generated in‐situ from Aldehydes and Amines by the NaBH4‐InCl3 System
Authors: Ravi Varala , Ramu Enugala , Vijay kumar Ponnamaneni , Srinivas rao Adapa 
Published: June 2006

AbstractA combination of sodium borohydride and a catalytic amount of indium(III) chloride in acetonitrile reduces imines formed in‐situ from aldehydes and amines to the corresponding functionalised secondary and tertiary amines in moderate to good yields. Noteworthy is that highly chemoselective reactions were achieved in the presence of other functional groups such as halogens, carbon‐carbon double bonds and hydroxyl groups.
Synthesis and Structural Characterization of Two Lead(II) Complexes of Bis(3,5‐dimethylpyrazolyl)methane
Authors: Li Qiao‐Yun , Zhang Wen‐Hua , Li Hong‐Xi , Ren Zhi‐Gang , Zhang Yong , Lang Jian‐Ping 
Published: June 2006

AbstractReactions of lead(II) nitrate or perchlorate with bis(3,5‐dimethylpyrazolyl)methane (dmpzm), produced two new Pb(II) chelated complexes [Pb(dmpzm)2X2] (X=NO−3 1, ClO−4 2). Both compounds were structurally characterized by elemental analysis, IR spectroscopy, thermal analysis, and single crystal X‐ray diffraction. Both compounds are mononuclear with a distorted square antiprismatic PbN4O4 coordination geometry incorporating a pair of O,O′‐bidentate anions and N,N′‐bidentate dmpzm ligands. In the crystals of 1 or 2, the methyl or methylene groups of dmpzm ligand interact with the oxygen atoms of nitrates or perchlorates to afford intra‐ and intermolecular hydrogen bonding, thereby forming a two‐dimensional network 1 or a three‐dimensional structure 2.
Asymmetric Access to Peptidyl β3‐Aldehydes by Coupling of N‐Phthalyl α‐Amino Acids with a Synthetic Heterocyclic β‐Amino Aldehyde Precursor
Authors: Yin Biaolin , Dhal Robert , Maisonneuve Vincent , Dujardin Gilles 
Published: June 2006

AbstractAsymmetric access to novel N‐protected (di)peptidyl β3‐aldehydes (“β3‐PAs”) has been achieved through direct coupling of a chiral non‐racemic 6‐alkoxytetrahydrooxazinone with N‐phthalyl L‐α‐amino acids. Kinetic resolution allows for the fruitful use of racemic amino acids in this process. Acidic hydrolysis of the diastereomerically pure, coupling products leads to the title N‐phthalyl‐β3‐PAs in high yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Rhodium‐Catalyzed Regio‐, Diastereo‐, and Enantioselective Intermolecular [4+2] Carbocyclization of 4‐Alkynals with Electron‐Deficient Alkenes
Authors: Tanaka Ken , Hagiwara Yuji , Hirano Masao 
Published: June 2006

AbstractWe established that a cationic rhodium(I)/dppf or dppb complex catalyzes a regio‐ and diastereoselective intermolecular [4+2] carbocyclization of 5‐trimethylsilyl‐4‐pentynals with electron‐deficient alkenes leading to cyclohexanones. We also established that a cationic rhodium(I)/(R,R)‐Walphos complex catalyzes a regio‐ and enantioselective intermolecular [4+2] carbocyclization of 5‐substituted 4‐pentynals and 2‐alkynylbenzaldehydes with N,N‐dialkylacrylamides leading to enantio‐enriched cyclohexanones and tetralones, respectively. A single olefin isomer was produced in every carbocyclization. Regioselectivities of the alkene insertion depend on the alkenes used. Mechanistic study suggested that a key intermediate in this intermolecular [4+2] carbocyclization is a five‐membered acylrhodium intermediate, formed by cis addition of the rhodium hydride to the metal‐bound alkyne. This method serves as an attractive new route to highly functionalized cyclohexanones in view of the one‐step access to 5‐substituted 4‐pentynals and 2‐alkynylbenzaldehydes starting from readily available terminal alkynes.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Somatosensory cortical plasticity in carpal tunnel syndrome treated by acupuncture
Authors: Napadow Vitaly , Liu Jing , Li Ming , Kettner Norman , Ryan Angela , Kwong Kenneth K. , Hui Kathleen K.S. , Audette Joseph F. 
Published: June 2006

AbstractCarpal tunnel syndrome (CTS) is a common entrapment neuropathy of the median nerve characterized by paresthesias and pain in the first through fourth digits. We hypothesize that aberrant afferent input from CTS will lead to maladaptive cortical plasticity, which may be corrected by appropriate therapy. Functional MRI (fMRI) scanning and clinical testing was performed on CTS patients at baseline and after 5 weeks of acupuncture treatment. As a control, healthy adults were also tested 5 weeks apart. During fMRI, sensory stimulation was performed for median nerve innervated digit 2 (D2) and digit 3 (D3), and ulnar nerve innervated digit 5 (D5). Surface‐based and region of interest (ROI)‐based analyses demonstrated that while the extent of fMRI activity in contralateral Brodmann Area 1 (BA 1) and BA 4 was increased in CTS compared to healthy adults, after acupuncture there was a significant decrease in contralateral BA 1 (P < 0.005) and BA 4 (P < 0.05) activity during D3 sensory stimulation. Healthy adults demonstrated no significant test–retest differences for any digit tested. While D3/D2 separation was contracted or blurred in CTS patients compared to healthy adults, the D2 SI representation shifted laterally after acupuncture treatment, leading to increased D3/D2 separation. Increasing D3/D2 separation correlated with decreasing paresthesias in CTS patients (P < 0.05). As CTS‐induced paresthesias constitute diffuse, synchronized, multidigit symptomatology, our results for maladaptive change and correction are consistent with Hebbian plasticity mechanisms. Acupuncture, a somatosensory conditioning stimulus, shows promise in inducing beneficial cortical plasticity manifested by more focused digital representations. Hum Brain Mapp, 2007. © 2006 Wiley‐Liss, Inc.
Electrophysiological and hemodynamic evidence for late maturation of hand power grip and force control under visual feedback
Authors: Halder Pascal , Brem Silvia , Bucher Kerstin , Boujraf Said , Summers Paul , Dietrich Thomas , Kollias Spyros , Martin Ernst , Brandeis Daniel 
Published: June 2006

AbstractSeveral human imaging studies have described the neural network involved in power grip under visual control and the subset of cortical areas within this network that are sensitive to force modulation. As there is behavioral evidence for late maturation in even simple hand motor tasks involving visual feedback, we aimed at identifying the neural correlates of these developmental changes. Subjects from three developmental age groups (9–11, 15–17, and adults) performed the same power grip task in both a functional magnetic resonance imaging and an event‐related potential (ERP) session. Trials started with a visual target indicating whether to squeeze at 20%, 40%, or 75% of their maximum and online visual feedback on the actual amount of force was provided. Longer reaction times and more shallow slopes of the force curve characterized the behavior of the younger age groups, especially the children. Both neurophysiological methods detected both general as well as force modulation‐specific maturational changes. General development was characterized by decreasing ERP amplitudes and increasing deactivation of an extended network, closely resembling the so‐called “default” network. The most pronounced developmental changes specific for force control were observed in an ERP component and brain regions involved in feedback processing. In contrast to adult subjects, we found evidence for a stronger dependency on visual feedback information in the younger age groups. Our results also suggest that the ability to deactivate task‐irrelevant networks might be a late developmental achievement. Hum Brain Mapp, 2007. © 2006 Wiley‐Liss, Inc.
Density of universal classes of series‐parallel graphs
Authors: Nešetřil Jaroslav , Nigussie Yared 
Published: June 2006

AbstractA class of graphs ${\cal C}$ ordered by the homomorphism relation is universal if every countable partial order can be embedded in ${\cal C}$. It is known (see [1,3]) that the class $\cal C_{k}$ of k‐colorable graphs, for any fixed ${k}\geq 3 $, induces a universal partial order. In 4, a surprisingly small subclass of $\cal C_{3}$ which is a proper subclass of the series‐parallel graphs (the K4‐minor‐free graphs) is shown to be universal. On another side, Pan and Zhu in 7 proved a density result that for each rational number ${a}/{b}\in [2,8/3]\cup\{3\} $, there is a K4‐minor‐free graph with circular chromatic number equal to a/b. In this note, we show for each rational number a/b within this interval the class $\cal K_{a/b} $ of K4‐minor‐free graphs with circular chromatic number a/b is universal if and only if $ a/b\neq2 $, 5/2 or 3. This shows yet another surprising richness of the K4‐minor‐free class that it contains universal classes as dense as the rational numbers. © 2006 Wiley Periodicals, Inc. J Graph Theory
Arc‐chromatic number of digraphs in which every vertex has bounded outdegree or bounded indegree
Authors: Bessy S. , Havet F. , Birmelé E. 
Published: June 2006

AbstractA k‐digraph is a digraph in which every vertex has outdegree at most k. A $(k \vee l)$‐digraph is a digraph in which a vertex has either outdegree at most k or indegree at most l. Motivated by function theory, we study the maximum value Φ (k) (resp. $\Phi^{\vee}(k, l)$) of the arc‐chromatic number over the k‐digraphs (resp. $(k \vee l)$‐digraphs). El‐Sahili [3] showed that $\Phi^{\vee}(k, k) \leq 2 k + 1$. After giving a simple proof of this result, we show some better bounds. We show $\max\{\log(2 k + 3), \theta(k + 1)\}\leq \Phi(k) \leq \theta(2 k)$ and $\max\{\log(2 k + 2 l + 4), \theta(k + 1), \theta(l + 1)\}\leq \Phi^{\vee}(k, l)\leq \theta (2 k + 2 l)$ where θ is the function defined by $\theta({{k}}) =\min \{{{s}} : {{{s}} \choose \left\lceil {{{{s}}}\over{{\rm{2}}}} \right\rceil} \geq {{k}} \}$. We then study in more detail properties of Φ and $\Phi^{\vee}$. Finally, we give the exact values of $\Phi({{k}})$ and $\Phi^{\vee}({{k}},{{l}})$ for ${{l}} \leq {{k}} \leq {\rm{3}}$. © 2006 Wiley Periodicals, Inc. J Graph Theory 53: 315–332, 2006
Guidelines for the optimization of microsurgery in atherosclerotic patients
Authors: Chen Hung‐Chi , Coskunfirat O. Koray , Özkan Ömer , Mardini Samir , Cigna Emanuele , Salgado Christopher J. , Spanio Stefano 
Published: June 2006

AbstractWe review the pathogenesis of atherosclerosis and the issues that must be taken into consideration when performing microsurgery in atherosclerotic patients. Atherosclerosis is a systemic disease, and may affect the success of microsurgery. Atherosclerotic patients have a tendency toward thrombosis, because the nature of the arteries is changed. Such patients are usually old and have additional medical problems. To increase the success rate of microsurgery in atherosclerotic patients, special precautions should be considered. Patients must be evaluated properly for the suitability of microsurgery. The microsurgical technique requires a meticulous approach, and various technical tricks can be used to avoid thrombosis. Recipient‐vessel selection, anastomotic technique, and the use of vein grafts are all important issues. Prophylactic anticoagulation is recommended in severely atherosclerotic patients. Close monitoring of the patient and flap is necessary after the operation, as with routine microvascular free‐tissue transfers. We conclude that atherosclerosis is not a contraindication for microsurgery. If the microsurgeon knows how to deal with the difficulties in atherosclerotic patients, microsurgery can be performed safely. © 2006 Wiley‐Liss, Inc. Microsurgery, 2006.
Isolation and Characterization of Starch from Seeds of Araucaria brasiliensis: A Novel Starch for Application in Food Industry
Authors: Bello‐Pérez Luis Arturo , García‐Suárez Francisco J. , Méndez‐Montealvo Guadalupe , Oliveira do Nascimento João Roberto , Lajolo Franco Maria , Cordenunsi Beatriz Rosana 
Published: June 2006

AbstractThe pinhão seeds (Araucaria angustifolia), are composed of 34% of starch and very low fractions of protein, lipids and phenolic compounds. This composition is favorable to obtain a stable, white in color and odorless starch, useful in the food industry. The isolated starch is constituted predominantly of small‐sized round granules (10–25 μm), rather than oval ones. Compared to corn starch, pinhão starch has a lower temperature and enthalpy of gelatinization. Retrogradation occurs to a lower extent in pinhão starch, due to its lower amylose content (∼25%). The pasting profile of pinhão starch showed a higher consistency than that of corn starch, with lower temperature in the peak of maximum viscosity. The higher swelling and solubility values of pinhão starch, in conjunction with the higher storage modulus (G') suggest new different applications of this novel starch. The low protein content of the starch granule favors applications like production of glucose and fructose syrups. The simple method of extraction and the high yield of starch from pinhão seed might be attractive not only for pilot‐plant but also for commercial‐scale production.
Effect of Cross‐linking with Epichlorohydrin on the Properties of Cassava (Manihot esculenta Crantz) Starch
Authors: Jyothi Alummoottil N. , Moorthy Subramoney N. , Rajasekharan Kallikat N. 
Published: June 2006

AbstractCassava starch was cross‐linked with epichlorohydrin (EPI) at 45°C for 2 h in three different media which include water, water in the presence of a phase transfer catalyst (PTC) and N,N‐dimethylformamide (DMF). The products were characterized by determining their physicochemical, thermal and retrogradation properties. In aqueous medium, the use of a PTC, tetrabutylammonium bromide (TBAB) produced derivatives with higher degree of cross‐linking than those prepared without the use of the catalyst. The degree of cross‐linking was found to be higher using the same concentration of EPI when the reaction was carried out in DMF. At low levels of cross‐linking, the peak viscosity of the cross‐linked starches increased in comparison to that of the native starch. With increasing degree of cross‐linking, the peak viscosity showed a significant reduction. The swelling volume, solubility and light transmittance of the starch pastes were lower for the modified starches. The cross‐linked starches showed slightly reduced values for the gelatinization temperatures, Tonset, Tpeak and Tend. The enthalpy of gelatinization of the modified starches increased with increase in the degree of cross‐linking. The modified starches exhibited higher water‐binding capacities (WBC) than the native starch; but with increase in the degree of cross‐linking, there was a gradual decrease in WBC. The in vitro alpha amylase digestibility of the modified starches decreased gradually with increase in the level of cross‐linking.
Analysis of Genotypic Diversity in the Starch Physicochemical Properties of Nonwaxy Rice: Apparent Amylose Content, Pasting Viscosity and Gel Texture
Authors: Bao Jinsong , Shen Shengquan , Sun Mei , Corke Harold 
Published: June 2006

AbstractA total of 499 non‐waxy rice lines including 172 landraces (the landrace set) and 327 cultivars and breeding lines (the breeding line set) were used to study the genetic diversity of starch physicochemical properties, and the differences between the landrace set and the breeding line set were compared. All the rice lines were planted in the same season and at the same location in Hainan province. Wide diversities of starch physicochemical properties were found, e.g. apparent amylose content ranged from 7.9% to 33% in normal rice and up to 39.8% in an amylose extender mutant; peak viscosity ranged from 90.1 to 305.4 RVU, hot paste viscosity from 77.5 to 248.1 RVU, and cold paste viscosity from 111.4 to 412.6 RVU; gel hardness ranged from 9.4 to 61.1 g. The breeding line set had a wider range of physicochemical properties than the landrace set with a rare exception in gel hardness. The mean values of nearly all the parameters showed significant differences between the two sets of rice except for the setback ratio. The adhesiveness and cohesiveness of landrace starches were significantly lower than those of the breeding lines whereas the other parameters of the landrace set were higher than those of the breeding line set. Analysis of correlation among these parameters indicated that most of the traits were significantly correlated. The wide range of physicochemical properties among non‐waxy rice lines allows breeders to obtain breeding lines with desirable grain quality and food processors to select unique rice materials for specialty food processing, in addition to the applications in other processing industries.