bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heme–heme interactions in tetramers and dimers of hemoglobin subunits: DeVoe theory calculations
Authors: Woody Robert W. 
Published: August 2005

AbstractDetectable exciton couplets arising from heme–heme interactions in the hemoglobin (Hb) tetramers of HbO2 and deoxyHb were predicted by DeVoe theory (Woody, in: Optical properties and structure of tetrapyrroles. Berlin: Walter deGruyter & Co.; 1985. p 239–259). This prediction was supported by the observation of an exciton couplet in the CD difference spectrum between the Hb tetramer and the αβ dimer of HbCO (Goldbeck et al., Biochem Biophys Res Commun 1997;235:610–614). In this paper, DeVoe theory is used to calculate the heme–heme interactions in the CO complex of the Hb tetramer (α2β2) and dimer (αβ), the systems studied by Goldbeck et al. The couplet strength of the resulting theoretical CD difference spectrum agrees well with experiment, thus confirming that heme–heme interactions contribute significantly to the CD of HbCO. Given that the heme–heme distances in HbCO are 25 Å and more, it is highly likely that heme–heme interactions also contribute significantly to the CD of other multi‐heme proteins, e.g., cytochrome c3, cytochrome oxidase, cytochrome bc1, etc., where the hemes are in closer proximity. © 2005 Wiley‐Liss, Inc. Chirality 17:450–455, 2005.
Synthesis, Characterization and Molecular Structures of Yttrium Trifluoroacetate Complexes with O‐ and N‐Donors: Complexation vs. Hydrolysis
Authors: Zhang Jianyong , Morlens Stéphanie , Hubert‐Pfalzgraf Liliane G. , Luneau Dominique 
Published: August 2005

AbstractDehydration and complexation reactions of [Y(TFA)3(H2O)3] (1; TFA = O2CCF3) were investigated with O‐ and N‐donor ligands in order to obtain suitable precursors for MOD (Metal Organic Deposition). Anhydrous adducts such as [Y2(μ,η2‐TFA)4(η1‐TFA)2(OHC2H4OiPr)4] (3), [Y2(μ,η2‐TFA)4(η1‐TFA)2(OHC2H4OC2H4OMe)2] (4), or [Y(TFA)3(triglyme)] (5) were isolated. The reactions with N‐donor ligands are more complex and afford mixed‐ligand derivatives such as [Y(TFA)3(H2O)2(LL)]m [LL = TMEDA (9), Me2NC2H4NMeC2H4NMe2 (10)] and, in the case of primary amines, yttrium oxohydroxo derivatives such as [H3O][Y3(μ3‐OH)(μ‐O)3(η1‐TFA)3(H2O)6(en)3] (6; en = NH2C2H4NH2). All complexes were characterized by elemental analysis, FT‐IR, and by single‐crystal X‐ray diffraction for 3, 4, and 6. All structurally characterized complexes contain on eight‐coordinate Y centers. Perfluorobutyrate and difluoroacetate derivatives were also prepared. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Stereoselective Construction of a Highly Functionalized Taxoid ABC‐Ring System: the C2–C9 Oxa‐Bridge Approach
Authors: Hamon Sylvain , Birlirakis Nicolas , Toupet Loïc , Arseniyadis Siméon 
Published: August 2005

AbstractThe goal of this investigation is to assemble the 20‐carbon unit 1 of the taxoid diterpene skeleton with a high level of stereocontrol by means of a three‐reaction sequence developed in this laboratory. The strategy involves seven C–C bond‐forming operations together with eighteen functional group transformations, circumventing the stereoselectivity issue altogether. Furthermore, there is no isomer formation and hence no need for chromatographic separation. A temporary oxa‐bridge (C2/C9) was used as a problem‐solving approach. The key step in the planned sequence was based on achieving the last C–C bonding between C11 and C12, following a successful C11 functionalization. X‐ray analyses of 8b, 17, 18, 19, 20, and 21, together with extensive use of 800 MHz 1H (200 MHz 13C) NMR spectra, support the suggested structures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Inviscid flow modelling using asymmetric implicit finite difference schemes
Authors: de Lange H. C. 
Published: August 2005

AbstractAsymmetric spatial implicit high‐order schemes are introduced and, based on Fourier analysis, the dispersion and damping are calculated depending on the asymmetry parameter. The derived schemes are then applied to a number of inviscid problems. For incompressible convection problems the proposed asymmetric schemes (applied as upwind schemes) lead to stable and accurate results. To extend the applicability of the proposed schemes to compressible problems acoustic upwinding is used. In a two‐dimensional compressible flow example acoustic and conventional upwinding are combined. Evaluation of all presented results leads to the conclusion that, of the studied schemes, the implicit fifth order upwinding scheme with an asymmetry parameter of about 0.5 leads to the optimal results. Copyright © 2005 John Wiley & Sons, Ltd.
Novel Copolyanhydrides Combining Strong Inherent Fluorescence and a Wide Range of Biodegradability: Synthesis, Characterization and in vitro Degradation
Authors: Jiang Hongliang , Chen Dian , Zhao Pengcheng , Li Yan , Zhu Kangjie 
Published: August 2005

AbstractSummary: In this work, a novel diacid monomer was synthesized in a very convenient scheme. The monomer is derived from naturally occurring products and emits strong fluorescence when polymerized to polyanhydride. The chemical structure of the monomer dCPS is as follows: HOC(O)ArOC(O)(CH2)2C(O)OArCOOH. Copolyanhydrides composed of dCPS and sebacic acid were further prepared by melt copolycondensation, and characterized by IR, NMR, UV‐Vis, DSC and fluorometry. The emission wavelength (λem) of the copolymers could be tuned by the excitation wavelength (λex). Fluorescence intensity increased with the increase of dCPS content. The microspheres fabricated from the copolymer with dCPS content as low as 10% could be clearly visualized with fluorescence microscopy. Either blue or green images of the microspheres could be captured with an excitation of UV and visible light. The degradation rate of the copolyanhydrides decreased as the dCPS fraction increased, and the degradation duration could be modulated from several days to more than three months. In addition, it was found that the copolyanhydrides displayed surface degradation characteristics. In view of the advantages of the novel copolyanhydrides, such as easy preparation, unique inherent luminescent properties, and widely adjustable degradation rate, they might be useful for biomedical engineering.Fluorescence spectra of P(dCPS:SA) excited at 462 nm and the fluorescent micrograph of the P(dCPS:SA) microsphere.magnified imageFluorescence spectra of P(dCPS:SA) excited at 462 nm and the fluorescent micrograph of the P(dCPS:SA) microsphere.
Adsorption of Chitosan onto Poly(D,L‐lactic acid) Particles: A Physico‐Chemical Investigation
Authors: Messai Isabelle , Delair Thierry 
Published: August 2005

AbstractSummary: Particles of poly(D,L‐lactic acid) (PLA) obtained by emulsification‐diffusion were surface‐modified by adsorption of chitosan. Thus, positively charged biodegradable carriers were obtained as potential carriers for DNA. Various physico‐chemical parameters, susceptible to impact the elaboration of such colloids, were investigated. External parameters were the ionic strength and the nature of the buffer; pH was fixed at 4.5 in order to ensure the ionisation of both counterparts. Internal parameters were the molar mass of chitosan and its degree of acetylation (DA). Kinetically, the adsorption of chitosan was spontaneous. Adsorption isotherms of chitosan were established using two different assays for chitosan, one based on the formation of a covalent bond, and the other on the formation of an ion pair. Two adsorption regimes were evidenced in ammonium acetate buffer. The amount of adsorbed chitosan increased with its molar mass up to a limit due to steric hindrance and with the DA. The latter effect could be explained by a reduction of the molecular dimensions of chitosan with DA. On storing, desorption of chitosan was dependent on the molar mass of the polysaccharide and, to a lesser extent, on the DA.Complexation isotherm of chitosan onto PLA particles.imageComplexation isotherm of chitosan onto PLA particles.
Structural Design of P(BMA‐co‐VTES)/TEOS Hybrid Membranes for Removal of Benzene from Water by Pervaporation
Authors: Ohshima Tadahiro , Matsumoto Moritoshi , Miyata Takashi , Uragami Tadashi 
Published: August 2005

AbstractSummary: The pervaporation performance of optimized poly(butylmetacrylate‐co‐vinyltriethoxysilane)/tetraethoxysilane (P(BMA‐co‐VTES)/TEOS) hybrid membranes for the removal of benzene from water was investigated. P(BMA‐co‐VTES)/TEOS hybrid membranes prepared by the sol–gel reaction were modified by annealing and trimethylsilylation to enhance the performance of these membranes. The annealing and trimethylmethoxysilane (TMS)‐modifications of P(BMA‐co‐VTES)/TEOS hybrid membranes gave more hydrophobic membranes compared with untreated P(BMA‐co‐VTES)/TEOS hybrid membranes and, consequently, the amount of benzene sorbed in the modified P(BMA‐co‐VTES)/TEOS hybrid membranes increased significantly. When an aqueous solution of dilute benzene was permeated by pervaporation through the annealed and TMS‐modified P(BMA‐co‐VTES)/TEOS hybrid membranes, the annealing treatment enhanced the benzene/water selectivity significantly. This result was attributed to a decrease in residual silanol groups in the annealed hybrid membranes and the formation of an optimum cross‐linked structure of the annealed P(BMA‐co‐VTES)/TEOS hybrid membranes.Benzene concentration in the permeate for an aqueous solution of benzene through untreated (○) and annealed (•) P(BMA‐co‐VTES)/TEOS hybrid membranes during PV.imageBenzene concentration in the permeate for an aqueous solution of benzene through untreated (○) and annealed (•) P(BMA‐co‐VTES)/TEOS hybrid membranes during PV.
Packing and Uniaxial Alignment of Liquid Crystalline Oligofluorenes
Authors: Chi Chunyan , Lieser Günter , Enkelmann Volker , Wegner Gerhard 
Published: August 2005

AbstractSummary: Liquid crystalline oligomers of 9,9‐bis(2‐ethylhexyl)fluorene of defined degree of polymerization 4, 5, 6, and 7 were investigated by X‐ray diffraction in the non‐oriented and in the aligned state. The diffraction data give evidence for a smectic B type phase for all of the oligomers. Quenching below the glass transition does not change the structure of the liquid crystalline phase. This allows to align spin‐coated films of these oligomers on rubbed polyimide substrates to give monodomain films. These are stable against thermal disordering below Tg, e.g. at room temperature. The degree of alignment is characterized by the dichroic spectra and polarized fluorescence spectra. Dichroic ratios and polarization ratios increase substantially with the chain length and values as high as D = 23 and P = 41 are obtained for the heptamer. The type of packing of the oligomers in the LC phase is discussed based on the X‐ray single crystal structure of models. In one such model the packing of the 2‐ethylhexyl side chains could be fully resolved, while the other model reveals the torsional angle between adjacent fluorene units in the same molecule as 144.2° which corroborates earlier work based on fiber diffraction of corresponding polyfluorenes.image
Dielectric Relaxation of Side‐Chain Liquid Crystalline Ionomers Containing Alkaline Metal Ions
Authors: Nikonorova Natalia A. , Barmatov Evgeny B. , Pebalk Dimitry A. , Diaz‐Calleja Ricardo , Kremer Friedrich 
Published: August 2005

AbstractSummary: Two sets of side‐chain, liquid‐crystalline ionomers based on copolymers of butyl acrylate and 4‐{[6‐(acryloyloxy)hexyl]oxy}benzoic acid containing 2.5–20 mol‐% of lithium or rubidium ions were studied. As the content of ions of alkali metals increases, segmental mobility markedly decreases. As compared with rubidium‐containing ionomers, ionomers containing lithium ions are characterized by a far more efficient decrease in their dielectric relaxation times because ionic radius of lithium ions is lower than that of rubidium ions.image
A New Method to Purify Highly Phosphonated Block Copolymers and Their Effect on Calcium Carbonate Mineralization
Authors: Wang Tongxin , Rother Gudrun , Cölfen Helmut 
Published: August 2005

AbstractSummary:Highly phosphonated double hydrophilic block copolymers (DHBCs) were synthesized through chain transfer radical polymerization or polymerization from a macro‐initiator. The DHBCs can be purified by a reprecipitation technique, in which any of the side products or precursors without phosphonate groups can be removed completely. This method provides a new route to purify other functional macromolecules with carboxylic, sulfonate groups etc. apart from dialysis and ultrafiltration. In addition, crystallization results show that the phosphonate groups have a strong influence on calcium carbonate mineralization. They can control the morphology of calcium carbonate from smooth spherical structures to porous structures even at a rather low concentration due to the strong effect of the phosphonate groups on crystallization of the mineral.image
An Application of Silica‐Based Monolithic Membrane Emulsification Technique for Easy and Efficient Preparation of Uniformly Sized Polymer Particles
Authors: Hosoya Ken , Bendo Mitsuko , Tanaka Nobuo , Watabe Yoshiyuki , Ikegami Tohru , Minakuchi Hiroyoshi , Nakanishi Kazuki 
Published: August 2005

AbstractSummary: Uniformly sized polymer particles were prepared by an emulsification and polymerization technique utilizing a silica monolithic membrane, namely the “silica monolithic membrane emulsification technique”. In this paper, we utilized silica monolithic membrane as a device for the preparation of uniformly sized polymer particles. A mixture of monomers, diluents and oil‐soluble initiator was emulsified into a continuous medium through the silica monolithic membrane and polymerized. The particles obtained had a higher size uniformity than that of particles prepared by previously reported membrane emulsification techniques, such as the Shirasu Porous Glass (SPG) emulsification technique. Through the silica monolithic membrane emulsification technique, we could prepare particles having availability as a possible packing material for solid‐phase extraction (SPE) and high performance liquid chromatography (HPLC).SEM photograph of silica particles prepared through capillary plate membrane.magnified imageSEM photograph of silica particles prepared through capillary plate membrane.
Compatibilization of Polyamide‐6/Polyarylate Blends by Means of an Ionomer
Authors: Retolaza Aritz , Eguiazábal José Ignacio , Nazábal Jon 
Published: August 2005

AbstractSummary: Polyamide‐6 (PA6)/polyarylate of bisphenol A (PAr) blends rich in PA6 and modified with an additional 15% poly[ethylene‐co‐(methacrylic acid)] partially neutralized with zinc (PEMA‐Zn) as a compatibilizer were obtained by melt mixing. Their phase structure, morphology, and mechanical performance were compared with those of the corresponding binary blends. The ternary blends were composed of a PA6 amorphous matrix and a dispersed PAr‐rich phase in which reacted PA6 and PEMA‐Zn were present. Additionally, minor amounts of a crystalline PA6 phase, and a PEMA‐Zn phase were also present. The chemical reactions observed led to a clear decrease in the dispersed particle size when PEMA‐Zn was added, indicating compatibilization. Consequently, the mechanical behavior of the blends with PEMA‐Zn improved, leading, mainly in the case of the blend with 10% PAr, to significant increases in both ductility and impact strength with respect to those of the binary blends. These increases were more remarkable than the slight decrease in stiffness as a consequence of the rubbery nature of the compatibilizer.Cryogenically fractured surface of the PA6/PAr‐PEMA‐Zn 70/30‐15 ternary blend.magnified imageCryogenically fractured surface of the PA6/PAr‐PEMA‐Zn 70/30‐15 ternary blend.
One‐Step Cationic Poly(D,L‐lactic acid) Particle Synthesis by Diafiltration and Interactions with Plasmid DNA
Authors: Messai Isabelle , Delair Thierry 
Published: August 2005

AbstractSummary: Diafiltration was used for the one step preparation of cationic poly(D,L‐lactic acid) particles in the presence of poly(ethylenimine) (PEI). First, parameters impacting the formation of plain PLA particles were investigated: the chemical nature of the solvent and the polymer concentration within the organic phase. Then, PEI was added to the organic solution and this mixture was subsequently dialyzed against water. The molecular architecture of the polycation was essential and colloidal particles were only obtained with a branched PEI of 25 000 g · mol−1. Increasing the PEI concentration in the mixture led to a particle mean size reduction and a zeta‐potential increase. In any case, a maximum of 8% of the initial PEI input was recovered at the interface. Finally, the study of the interactions of these colloids with DNA showed that the amount of DNA bound at the saturation plateau increased with increasing inputs of PEI in the formulation.SEM micrograph of cationic poly(D,L‐lactic acid) particles.magnified imageSEM micrograph of cationic poly(D,L‐lactic acid) particles.
Diversification of CDK11 transcripts during chicken testis development and regression
Authors: Francone Victor P. , Mezquita Jovita 
Published: August 2005

AbstractCDK11 (cyclin‐dependent kinase 11, formerly known as PITSLRE) is a serine/threonine kinase that associates with the cyclin L2 regulatory partner. CDK11 catalytic activity has been associated with apoptosis, transcription, and RNA processing. Here, we identify novel chicken testis CDK11 transcripts that differ in their 5′UTR, 3′UTR, splicing of the exon 6, and polyadenylation. We have also characterized the differential expression of CDK11 in somatic tissues, during testis development and upon testicular regression by diethylstilbestrol (DES) treatment. The heterogeneity of CDK11 transcripts presented in this study suggests new possibilities for post‐transcriptional regulation. Mol. Reprod. Dev. © 2005 Wiley‐Liss, Inc.
A mouse gene encoding a novel member of the WD family of proteins is highly conserved and predominantly expressed in the testis (Wdr13)
Authors: Suresh Amritha , Shah Vanya , Rani Deepa Selvi , Singh Bhupendra N. , Prasad Gogineni Uma , Subramanian Subbaya , Kumar Satish , Singh Lalji 
Published: August 2005

AbstractWdr13, a novel member of the WD family of proteins and the mouse homolog of WDR13 is localized to the locus XA1.1 and is predominantly expressed in the testis. The expression begins at the early stages of gonadal development and is maintained throughout the adult life with a predominant expression in the germ cells of adult testis. RNA in situ hybridization on the testis and brain sections indicated a cytoplasmic expression of the transcript. The alternatively spliced transcripts of the gene are generated by different methods and showed a differential pattern of expression, suggesting functional diversity. The expression of the gene in the unfertilized egg and in the neural stem cells indicated the functional significance of the gene from the early stages of development. The nuclear localization of the mouse WDR13 protein suggested a regulatory function. Evolutionary analysis of the gene indicated an extensive functional conservation across diverse species. Comparison of the genomic organization of the different homologs revealed a varied organization in the invertebrate homolog and the retention of the functionally significant introns in the same. Mol. Reprod. Dev. © 2005 Wiley‐Liss, Inc.
A note on trees, tables, and algorithms
Authors: Goddard Wayne , Hedetniemi Stephen T. 
Published: August 2005

AbstractSeveral algorithms for optimal vertex subsets in trees are given by simple tables. In this article we investigate the properties of and operations on these tables. We use known techniques for combining tables to correct a table in the literature; give a necessary and sufficient condition for a table to correspond to some tree property; discuss the question of dividing one table by another; explain how to derive a table from a set of representatives; and apply this to finding the table for the parameter external redundance. All of this is facilitated by computer software. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009
The element connectivity parameterization formulation for the topology design optimization of multiphysics systems
Authors: Ho Yoon Gil , Young Kim Yoon 
Published: August 2005

AbstractIn spite of the success of the element‐density‐based topology optimization method in many problems including multiphysics design problems, some numerical difficulties, such as temperature undershooting, still remain. In this work, we develop an element connectivity parameterization (ECP) formulation for the topology optimization of multiphysics problems in order to avoid the numerical difficulties and yield improved results. In the proposed ECP formulation, finite elements discretizing a given design domain are not connected directly, but through sets of one‐dimensional zero‐length links simulating elastic springs, electric or thermal conductors. The discretizing finite elements remain solid during the whole analysis, and the optimal layout is determined by an optimal distribution of the inter‐element connectivity degrees that are controlled by the stiffness values of the links. The detailed procedure for this new formulation for multiphysics problems is presented. Using one‐dimensional heat transfer models, the problem of the element‐density‐based method is explained and the advantage of the ECP method is addressed. Copyright © 2005 John Wiley & Sons, Ltd.
Solving eigenvalue problems by implicit decomposition
Authors: Luo Jenn‐Ching 
Published: August 2005

AbstractThis paper presents three innovative methods for solving eigenvalue problems for differential equations based upon the techniques of implicit decomposition developed by Luo and Friedman. An eigenvalue problem can be written as an approximate algebraic system of the form [K]{X} + λ[M]{X} = 0 by employing finite elements. These methods provide robust techniques to compute the real eigenpair, λ and {X}, where [K] and [M] can be asymmetric, indefinite, and even singular.
Semigroup linearization for nonlinear parabolic equations
Authors: Epperson James F. 
Published: August 2005

AbstractWe present an algorithm for nonlinear parabolic equations that uses a linear semigroup approach to decouple the nonlinearity, thus allowing simpler techniques to be used for the solution. The basic method is applicable only to a restricted class of problems, but can be extended with little loss of utility. Stability and error estimates are given, along with example computations.
Speciation analysis and the assessment of bioavailability of manganese in phytomedicines by extraction with octanol and determination by flame atomic absorption spectrometry
Authors: Shun‐xing Li , Feng‐ying Zheng , Xian‐li Liu , Wen‐lian Cai 
Published: August 2005

AbstractTrace elements in phytomedicines are present in the form of metallic complexes. Since n‐octanol, a long‐chain alkanol, presents a conguration similar to that of carbohydrates and lipids, the lipophilicity and absorptivity of organic medicines may be assessed from their distribution coefcients between octanol and water. This strategy has been used in order to dene the species of manganese in a number of phytomedicines and to study the distribution of manganese in decoctions of phytomedicines in the stomach and the intestine. The concentrations of manganese in the original herbal materials and in octanol‐ and water‐soluble fractions were determined by flame atomic absorption spectrometry following mixed acid digestion. The acidities of gastric and intestinal juices, the phytomedical composition and the compatibility of phytomedicines, i.e. the combination of single phytomedicines, greatly affected the manganese complexing ligands and determined the species and bioavailability of manganese. It is concluded that a knowledge of the level of octanol‐soluble manganese in a phytomedicine could form the basis of dosage design in order to avoid manganese overload. Copyright © 2005 John Wiley & Sons, Ltd.