bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functionalization of magnetic nanoparticles with organic molecules: Loading level determination and evaluation of linker length effect on immobilization
Authors: Srinivasan Balasubramanian , Huang Xuefei 
Published: June 2007

AbstractA general method is introduced to immobilize organic molecules on magnetic nanoparticles through silanization reactions and determine the maximum loading level by UV–vis spectroscopy. Loading levels of 1.5 × 10−3 mol per gram of nanoparticle were obtained with structurally diverse compounds such as rhodamine B and glucosamine. The length of the linker did not have a significant effect on loading as comparable maximum amounts of rhodamine B were immobilized on magnetic nanoparticles regardless of the linker length. Interestingly, rhodamine B derivatives lost conjugation during synthetic manipulations due to reversible spiroisobenzofuran formation. Full regeneration of conjugation was found to be slow with rhodamine B attached on magnetic nanoparticles. The results obtained from these studies will be useful for studying surface functionalization of MNPs in general. Chirality, 2008. © 2007 Wiley‐Liss, Inc.
Chiroptical properties and racemization behavior of highly distorted donor‐acceptor tetracyanoanthraquinodimethane with interconvertible planar chirality
Authors: Saito Hideaki , Mori Tadashi , Origane Yumi , Wada Takehiko , Inoue Yoshihisa 
Published: June 2007

AbstractAbsolute configuration of optically active 7,12‐bis(dicyanomethylene)‐7,12‐dihydrobenz[a]anthracene (1) with interconvertible planar chirality was determined by a comparison of experimental and theoretical circular dichroism (CD) spectra. Upon standing at ambient temperatures, 1 was found to spontaneously racemize, the rates of which were assessed through the separation profiles of chiral HPLC at 5–20°C and also from the CD spectral decay profiles at the same temperatures. Mechanism of the racemization was discussed. Chirality, 2008. © 2007 Wiley‐Liss, Inc.
Absorption flattening as one cause of distortion of circular dichroism spectra of Δ‐RuPhen3 · H2TPPS complex
Authors: Castiglioni Ettore , Abbate Sergio , Longhi Giovanna , Gangemi Roberto , Lauceri Rosaria , Purrello Roberto 
Published: June 2007

AbstractTo extend the model that explains why and how much absorption flattening (AF) influences circular dichroism (CD) signals, we have investigated the interesting case of exciton CD in the Soret region of a noncovalent complex formed by (Δ‐RuPhen3)2+ and the tetraanionic porphyrin H2TPPS. Different concentrations have been studied by using an AF emulator and spectra simulation. The CD spectra of this compound occasionally show distortions in the solution sampling mode with the increase of concentration; the inhomogeneous distribution in the cell volume is due to aggregation and is the source of the AF effect. On the basis of these results, we conclude that AF is an important cause of distortions in CD spectra for Δ‐RuPhen3 · H2TPPS complexes and might affect the CD bands of other aggregated systems as well. Chirality 19:642–646, 2007 © 2007 Wiley‐Liss, Inc.
Excess control and the risk of corporate expropriation: Canadian evidence
Authors: Attig Najah 
Published: June 2007

AbstractCorporate governance in Canada was examined by looking at the ultimate ownership structure of a large sample of publicly traded firms. Results suggest that small investors in Canada are vulnerable to corporate expropriation in large firms. Despite the similarities in institutional indexes, Canada displays different patterns of ownership structure than sister Anglo‐Saxon countries (the U.S. and the U.K). More importantly, results suggest that excess control drives expropriation over and above the typical Jensen type of agency problems that are attributable to regular separation of ownership and control. Equally important, firms headquartered in Quebec appear to be undervalued vis‐à‐vis firms headquartered in the rest of Canada. Copyright © 2007 ASAC. Published by John Wiley & Sons, Ltd.
Refining momentum strategies by conditioning on prior long‐term returns: Canadian evidence
Authors: Deaves Richard , Miu Peter 
Published: June 2007

AbstractCross‐sectional returns in Canada are predictable using both momentum and reversal strategies. Synergies realized by focusing on the entire term structure of prior returns lead to better predictability. An enhanced index strategy based on these synergies is profitable most of the time after controlling for transaction costs, although the degree of profitability changes over time. Simulation shows that recent profitability is mainly attributable to the short‐side of the momentum strategy. Copyright © 2007 ASAC. Published by John Wiley & Sons, Ltd.
Theoretical Study on Co3+ in Aqueous Solution in Terms of ABEEM/MM Model
Authors: Guan Qing‐Mei , Yang Zhong‐Zhi 
Published: June 2007

AbstractA detailed theoretical investigation on Co3+ hydration in aqueous solution has been carried out by means of molecular dynamics (MD) simulations based on the atom‐bond electronegativity equalization method fused into molecular mechanics (ABEEM/MM). The effective Co3+ ion‐water potential has been constructed by fitting to ab initio structures and binding energies for ionic clusters. And then the ion‐water interaction potential was applied in combination with the ABEEM‐7P water model to molecular dynamics simulations of single Co3+(aq.) solution, managing to reproduce many experimental structural and dynamical properties of the solution. Here, not only the common properties (radial distribution function, angular distribution function and solvation energy) obtained for Co3+ in ABEEM‐7P water solution were in good agreement with those from the experimental methods and other molecular dynamics simulations but also very interesting properties of charge distributions, geometries of water molecules, hydrogen bond, diffusion coefficients, vibrational spectra are investigated by ABEEM/MM model.
Studies on PNPP Hydrolysis Catalyzed by Schiff Base Cobalt(II) Complexes Containing Benzoaza‐15‐crown‐5
Authors: Hu Wei , Wang Ying , Li Jian‐Zhang , Du Juan , Meng Xiang‐Guang , Hu Chang‐Wei , Zeng Xian‐Cheng 
Published: June 2007

AbstractThree novel Schiff base cobalt(II) complexes containing benzoaza‐15‐crown‐5, CoL1, CoL2 and CoL3 were synthesized and characterized, and these complexes were used in catalytic hydrolysis of carboxylic ester (PNPP, p‐nitrophenyl picolinate) as mimic hydrolytic metalloenzyme. The analysis of specific absorption spectra of the hydrolytic reaction systems indicated that the catalytic hydrolysis involved the key intermediates formed by PNPP with cobalt(II) complexes. The CoL3 bearing the electron withdrawing group shows better catalytic activity due to its stabilization effect on active species MLS−. The catalytic mechanism of PNPP hydrolysis was also proposed. The kinetic parameter of PNPP catalytic hydrolysis has been calculated and the activation energy for the catalytic hydrolysis is 43.69, 39.76 and 35.44 kJ·mol−1, respectively.
Naphthalimide as Highly Selective Fluorescent Sensor for Ag+ Ions
Authors: Xu Sheng , Li Wei , Chen Kong‐Chang 
Published: June 2007

AbstractThe naphthalimide derivative NA1 was synthesized, which consists of a bis(2‐(ethylthio)ethyl)amine group binding cations and naphthalimide unit as chromogenic and fluorogenic signaling subunit. Absorption and emission spectra and the effect of polarity of solvents and pH values were studied. The photo‐induced electron transfer (PET) occurred from the donor of bis(2‐(ethylthio)ethyl)amine group to the naphthalimide fluorophore. The present study demonstrates that NA1 is a viable candidate as a fluorescent receptor for a new Ag+ ion sensor. This silver ion chemosensor can discriminate Ag+ ion well among heavy metal ions by an enhancement of the fluorescence intensity in ethanol‐water (1:9, V:V). And NA1 is also a pH‐sensor because the fluorescence of the compound varies with the pH values.
Crystal Structures and Theoretical Calculation of Zn(II) and Cu(II) Supramolecular Complexes Based on Macrocyclic Triamine Ligand 1,4,7‐Triazacyclodecane (tacd)
Authors: Guo Hui , Zhu Hai‐Yan , He Xian‐Ling , Su Zhen‐Ping , Li Jun , Zhang Feng‐Xing 
Published: June 2007

AbstractTwo supramolecular complexes [Zn(tacd)2](C6H8O4)·6H2O (1) and [Cu(tacd)2]Cl2·4H2O (2) were synthesized and characterized by elemental analysis, IR spectra, TGA and single‐crystal X‐ray diffraction analysis. The crystal structure showed that the metal ions in complexes 1 and 2 had similar coordination circumstance. But for the complex 2, it formed a novel two‐dimensional supramolecular network with 12‐membered rings and four‐membered rings via hydrogen bond interaction. The thermal gravimetric analyses indicated that the two complexes had similar steps of weight‐loss. On the basis of experiment, the two complexes were calculated by DFT‐B3LYP/6‐31G(d) in Gaussian 03. The results of calculation are in good agreement with the experiment.
Synthesis, Characterization and SOD Activities of IP‐copper(II)‐L‐amino Acid Complexes
Authors: Gu Qin , Le Xue‐Yi , Lin Qing‐Bin , Liao Sheng‐Rong , Ma Xue‐Dan , Feng Xiao‐Long 
Published: June 2007

AbstractFour new ternary complexes: [Cu(IP)(L‐Val)(H2O)]ClO4·1.5H2O (1), [Cu(IP)(L‐Leu)(H2O)]ClO4 (2), [Cu(IP)(L‐Tyr)(H2O)]ClO4·H2O (3) and [Cu(IP)(L‐Trp)(H2O)]ClO4·1.5H2O (4) have been synthesized and characterized by elemental analysis, molar conductivity, infrared absorption spectroscopy, electronic absorption spectroscopy and cyclic voltammetry, where IP=imidazo[4,5‐f][1,10] phenanthroline, L‐Val=L‐valinate, L‐Leu=L‐leucinate, L‐Tyr=L‐tyrosinate and L‐Trp=L‐tryptophanate. Complex 3 was structurally characterized by X‐ray diffraction method, which crystallizes in orthorhombic space group P21212 in a unit cell of dimensions a=3.0567(4) nm, b=0.74079(9) nm, c=1.06198(13) nm, V=2.4047(5) nm3, Z=4, μ=0.1084 cm−1. The SOD‐like activities of catalytic dismutation of superoxide anions (O−2) by the complexes were determined by means of modified nitroblue tetrazolium (NBT) photoreduction. The IC50 values of complexes 1, 2, 3 and 4 are 0.072, 0.147, 0.429 and 0.264 µmol·L−1, respectively.
Synthesis of 15‐Demethyl Brefeldin A and Its 7‐epi Isomer
Authors: Shen Xin , Yang Yong‐Qing , Hu Qi , Huang Jia‐Hui , Gao Jian , Wu Yi‐Kang 
Published: June 2007

AbstractSynthesis of 15‐demethyl brefeldin A and its 7‐epimer is detailed. X‐ray crystallographic structure for 15‐demethyl brefeldin A is also disclosed.
Diels‐Alder Reactions of N‐Functionalized Acryloyl α‐Pyrrolidone Derivatives Using FeCl3·6H2O as an Efficient Catalyst under Solvent‐free Conditions
Authors: Pei Wen , Wang Yong‐Jiang , Yu Chang‐Quan 
Published: June 2007

AbstractDiels‐Alder reactions of N‐functionalized acryloyl α‐pyrrolidone derivatives were investigated, which were catalyzed by FeCl3·6H2O as an efficient catalyst under solvent‐free conditions at room temperature. The corresponding cycloadducts with functionalized‐pyrrolidone were prepared in high yield with high stereoselectivity by a green chemistry procedure. N‐Functionalized acryloyl pyrrolidone derivatives, a kind of pyrrolidone‐functionalized chelating α,β‐unsaturated ketone usable as a dienophile in Diels‐Alder reaction, were synthesized by N‐acylation procedure in ionic liquid as a novel synthetic method.
An Efficient and Solvent‐Free Reaction for Synthesis of Bis(indol‐3‐yl)methanes Catalyzed by Sulfamic Acid
Authors: An Li‐Tao , Ding Fei‐Qing , Zou Jian‐Ping , Lu Xiao‐Hua , Zhang Li‐Li 
Published: June 2007

AbstractSA (sulfamic acid) catalyzes the reaction of indole with aldehyde and ketone to afford bis(indol‐3‐yl)methanesin good to excellent yields under solvent‐free condition at ambient temperature.
Baylis‐Hillman Reactions of Sulfonyl Aldimines or Aryl Aldehydes with 3‐Methylpenta‐3,4‐dien‐2‐one or 3‐Benzylpenta‐3,4‐dien‐2‐one
Authors: Shi Min , Guo Ying‐Wen , Li Hong‐Bin 
Published: June 2007

AbstractThe attempted Baylis‐Hillman reactions of sulfonyl aldimines or aryl aldehydes with 3‐methylpenta‐3,4‐ dien‐2‐one or 3‐benzylpenta‐3,4‐dien‐2‐one gave the corresponding Baylis‐Hillman adducts in moderate yields in DMSO under the catalysis of DBU or PMe3, respectively. Moderate diastereoselectivities were observed in the reaction of 3‐benzylpenta‐3,4‐dien‐2‐one with N‐arylmethylidene‐1‐naphthalenesulfonamides catalyzed by chiral catalyst cinchona alkaloid derivative TQO {4‐(3‐ethyl‐4‐oxa‐1‐azatricyclo[4.4.0.03,8]dec‐5‐yl)quinolin‐6‐ol}.
Aqueous Media Oxidation of Alcohols with Ammonium Persulfate
Authors: Imanzadeh Gholam Hassan , Zamanloo Mohammad R. , Mansoori Yaghoob , Khodayari Ali 
Published: June 2007

AbstractOxidation of series of various primary and secondary alcohols to corresponding carbonyl compounds with ammonium persulfate in aqueous media was described. No over oxidation of primary alcohols to carboxylic acids and secondary alcohols to esters was observed. Under such conditions benzoin was converted to benzoic acid.
Catalytic Hydrogenation of α,β‐Epoxyketones to β‐Hydroxy‐ ketones with Two Sulfinyl Analogues of Coenzyme NADH Models
Authors: Xie Kun , Cui Yi , Liu You‐Cheng , Fu Yao 
Published: June 2007

AbstractAn efficient method for the selective hydrogenation of a series of α,β‐epoxyketones to β‐hydroxyketones using catalytic amount of two sulfinyl analogues of NAD+ model compounds is reported. The lack of any diastereoselectivity for the formation of β‐hydroxyketones with optically pure sulfinyl analogue of NAD+ model supports the radical mechanism proposed previously.
New Aliphatic Alcohol and Ester Constituents from Rice Hulls of Oryza sativa
Authors: Chung ILL‐Min , Ali Mohd , Chun Se‐Chul , Jin Cheng‐Wu , Cho Dong‐Ha , Hong Seung‐Beom , Ahmad Ateeque 
Published: June 2007

AbstractSix new aliphatic alcohol and ester compounds of n‐octacos‐9‐enyl propionate (1), 4‐(3‐formylheptyl)cyclo‐ hexyl 4‐(cyclohexylcarbonyloxymethyl)cyclohexyl‐carboxylate (2), n‐hentriacont‐25‐en‐5α‐ol (3), n‐hexetriacont‐ 9,26‐dien‐8α,11β,23α‐triol (4), n‐tetracontan‐15α‐ol (5) and n‐tritetracontan‐5α‐ol (6) were isolated from the hulls of Oryza sativa. The structures were established on the basis of spectroscopic analysis.
Study on Electric Double Layer of a Cylindrical Particle with Functional Theoretical Approach
Authors: Wang Zheng‐Wu , Liu Xue‐Min , Yu Hui‐Xin , Zhou Ming , Jin Jian 
Published: June 2007

AbstractA new method, i.e. the iterative method in functional theory, was introduced to solve analytically the nonlinear Poisson‐Boltzmann (PB) equation under general potential ψ condition for the electric double layer of a charged cylindrical colloid particle in a symmetrical electrolyte solution. The iterative solutions of ψ are expressed as functions of the distance from the axis of the particle with solution parameters:the concentration of ions c, the aggregation number of ions in a unit length m, the dielectric constant T, the system temperature T and so on. The relative errors show that generally only the first and the second iterative solutions can give accuracy higher than 97%. From the second iterative solution the radius and the surface potential of a cylinder have been defined and the corresponding values have been estimated with the solution parameters. Furthermore, the charge density, the activity coefficient of ions and the osmotic coefficient of solvent were also discussed.
Phase Structures of Nascent Polyethylene Powder Studied by Wideline Proton NMR
Authors: Yan Xiao‐Wei , Wang Jing‐Dai , Ren Xiao‐Hong , Yang Yong‐Rong , Jiang Bin‐Bo , Voda Mihai Adrian , Bertmer Marko , Stapf Siegfried 
Published: June 2007

AbstractThe wideline proton NMR spectra of polyethylene powder samples were analyzed in terms of contributions from three components:(1) a rigid part with immobile chains, (2) a soft region with liquid‐like character which produces a Lorentzian contribution to the spectrum, and (3) an intermediateregion in which the rotation of methylene groups about C–C bonds is partially hindered. The relative mass fractions as well as chain mobilities varied greatly among samples produced by different polymerization techniques. The NMR crystallinity agreed well with that estimated by WAXD and was much higher than DSC crystallinity, indicating an inclusion of the contribution from a crystalline‐amorphous interphase. The crystalline defects in the rigid part could be significantly affected by processing parameters when employing the same type of polymerization technique. The intermediate region in the NMR spectra was analyzed according to the comparison between bimodal high density polyethylene and corresponding linear unimodal one. It was found that the mass fraction of the NMR interphase could be an indication of the percentage of tie molecules between crystalline lamellae and thus may significantly affect the mechanical properties of polymeric material.
A New Method of Synthesis of Azo Schiff Base Ligands with Azo and Azomethine Donors: Synthesis of N‐4‐Methoxy‐benzylidene‐2‐(3‐hydroxyphenylazo)‐5‐hydroxy‐aniline and Its Nickel(II) Complex
Authors: Oforka N. C. , Mkpenie V. N. 
Published: June 2007

AbstractA new method for the synthesis of azo Schiff an base ligand in which the azo and azomethine groups are coordination sites was developed through a Schiff base precursor. The precursor, N‐4‐methoxybenzylidene‐3‐hydroxy‐phenylamine (SB) derived from 3‐aminophenol was regioselectively coupled with a diazonium ion para to the hydroxyl group of the amine component of the Schiff base. The para selectivity was controlled by the directing effect of the hydroxyl group. The ligand and its nickel(II) complex were characterized by elemental analyses, IR and UV‐Vis spectroscopy. The analytical and spectral data supported the mononuclear formulation of the complex with metal to ligand ratio (M:L=1:2) and suggested a square planar geometry for the complex.
Pulmonary and extrapulmonary poorly differentiated large cell neuroendocrine carcinomas
Authors: Faggiano Antongiulio , Sabourin Jean‐Cristophe , Ducreux Michel , Lumbroso Jean , Duvillard Pierre , Leboulleux Sophie , Dromain Clarisse , Colao Annamaria , Schlumberger Martin , Baudin Eric 
Published: June 2007

AbstractBACKGROUND.Poorly differentiated large cell neuroendocrine carcinomas (LCNEC) comprise a rare and still scarcely known subgroup of neuroendocrine tumors. The objective of this study was to investigate the epidemiology, clinical presentation, prognostic factors, and molecular pathways of patients with poorly differentiated LCNEC.METHODS.Forty‐one patients who had a confirmed diagnosis of poorly differentiated LCNEC according to the criteria of the most recent World Health Organization classification of neuroendocrine tumors of the lung entered the study. The clinicopathologic features of patients with poorly differentiated LCNEC were reviewed, prognostic parameters for their survival were studied, and the prognostic roles of the proteins involved in cell cycle regulation were investigated with tissue array analysis in a subset of patients with LCNEC.RESULTS.Twenty‐four men and 17 women with a median age of 63 years (age range, 26–81 years) who had LCNEC were studied. LCNEC developed after therapy for a first cancer in 14% of patients. Neither a personal or familial history of endocrine tumors nor a primary association that was compatible with an inherited syndrome was observed. The increase of at least 1 serum biologic marker was observed in 93% of patients. A primary tumor was identified in only 63% patients. Thirty‐one patients had distant metastases, and 10 patients had only lymph node metastases at the time of the diagnosis. The 5‐year survival rate was 24%. High mitotic count, low expression of neuroendocrine markers, and a Bcl‐2/Bax ratio > 1 were unfavorable prognostic factors for survival (P < .01). All patients who had isolated peripheral lymph node LCNEC achieved a cure.CONCLUSIONS.The results from this study highlighted distinctive clinical features and prognostic indicators of poorly differentiated LCNEC. Peripheral isolated lymph node clinical presentation is proposed as a new clinical entity. Cancer 2007. © 2007 American Cancer Society.
Telomere length in peripheral blood cells of germline TP53 mutation carriers is shorter than that of normal individuals of corresponding age
Authors: Trkova Marie , Prochazkova Kamila , Krutilkova Vera , Sumerauer David , Sedlacek Zdenek 
Published: June 2007

AbstractBACKGROUND.A decrease in the age at cancer onset and increase in cancer incidence in successive generations in Li‐Fraumeni syndrome (LFS) families with germline TP53 mutations have been previously described. In the current study a possible relation was analyzed between telomere length and cancer onset in TP53 mutation carriers.METHODS.Telomere length was measured using real‐time quantitative polymerase chain reaction (PCR) in 20 carriers of germline TP53 mutations and in 83 unrelated healthy individuals. According to the age at blood sampling, patients and controls were divided into 2 age groups, children and adults. Telomere length was correlated to TP53 mutation status and telomere shortening in patients to the age at cancer onset. A t‐test and linear regression were used to analyze the data.RESULTS.Compared with healthy controls, telomere length was significantly shorter both in the child (P = .001) and adult (P = .034) germline T53 mutation carriers. Although a statistically significant correlation between telomere shortening and the age at cancer onset was not observed, there was a trend of shorter telomeres in mutation carriers affected in childhood compared with those affected later in life. Neither cancer therapy nor sex differences were likely to affect the results.CONCLUSIONS.The findings suggest a possible link between the carriership of a germline TP53 mutation, telomere length, predisposition to early‐onset cancer, and anticipation in LFS. Cancer 2007. © 2007 American Cancer Society.
Development of the vomeronasal amygdala in anuran amphibians: Hodological, neurochemical, and gene expression characterization
Authors: Moreno Nerea , González Agustín 
Published: June 2007

AbstractThe organization of the amygdaloid complex in amphibians possesses major features shared with amniotes. Basic subdivisions have been identified and tentatively compared with their counterparts in other tetrapods. However, problems appeared when trying to find homologies for the amphibian vomeronasal amygdala, the medial amygdala (MeA), because of its embryological origin and, therefore, its evolutionary significance could not be established. Thus, in the present study the main characteristics of the MeA in anurans were studied during development by means of tract‐tracing, immunohistochemical, and gene expression techniques. The connectivity of the MeA, mainly related to the accessory olfactory bulb and the hypothalamus, and the localization of neurochemical markers such as substance P, somatostatin, and GABA strongly support its homology with the medial amygdala (subpallial) of mammals. In addition, analysis of the expression patterns of the LIM‐homeodomain genes x‐Lhx5/7/9 in the developing MeA, together with the immunohistochemistry for GABA and the transcription factor NKX2.1, evidence its resemblance to the subpallial component of the vomeronasal amygdala of mammals in terms of embryological origin and, most likely, the presence of migrated cells from other territories. No evidence was found for pallial‐derived territories in the vomeronasal amygdala of anurans that could be comparable to the cortical portions that exist in amniotes, suggesting that these cortical components have emerged in the anamnio‐amniotic transition in the evolution of tetrapods. J. Comp. Neurol. 503:815–831, 2007. © 2007 Wiley‐Liss, Inc.