bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular Recognition – Allosterism Generated by Weak Host–Guest Interactions in Molecular Rectangles
Authors: Crowley James D. , Steele Ian M. , Bosnich Brice 
Published: August 2005

AbstractTwo metal‐based molecular rectangles that bear two identical binding sites form 1:2 host–guest adducts with a pair of analogous planar Pt2+ complexes. The larger of the two guests shows no binding allosterism with either of the two rectangles, but substantial positive allosterism is observed when the smaller guest binds to the rectangles. It is proposed that the smaller guest is better accommodated in the binding sites of the receptor and that this leads to allosterism. Various experiments, including 1H NOESY spectroscopy, support the supposition that the smaller guest is better incarcerated in the receptors. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Storage stability study of margarines produced from enzymatically interesterified fats compared to margarines produced by conventional methods. I. Physical properties
Authors: Zhang Hong , Jacobsen Charlotte , Adler‐Nissen Jens 
Published: August 2005

AbstractIn this study, margarine hardstocks were produced from two enzymatically interesterified fats at conversion degrees of 80 and 100%, a chemically randomized fat and a physically mixed fat, respectively. These four hardstocks blended with 50% of sunflower oil were mainly used for the production of table margarines in a pilot plant. Storage stability studies were carried out at storage temperatures of 5 and 25 °C during 12 wk. Margarines from the enzymatically interesterified fats were compared to the margarines produced by conventional methods and to selected commercial products. The changes in the physical properties of margarines, including hardness, dropping point, crystal form, and sensory evaluation, were examined during storage. It was observed that margarine storage stability increased with increasing conversion degree. The color of margarines made from the enzymatically interesterified fats was more similar to that of the physically mixed fat than that of the margarine from the chemically randomized fat, which had less color. Crystal transformation was accelerated at high storage temperature. Crystal size was not only related to the types of crystals, but also to the driving force of temperature difference. A larger crystal size was observed at 5 °C than at 25 °C for the margarine made from the blend. Margarines produced from interesterified fats had better physical properties than the blend. Overall, the margarine produced from the enzymatically fully converted fat had physical properties similar to the margarine produced from the chemically interesterified fat.
A Facile and Potent Synthesis of meso,meso‐Linked Porphyrin Arrays Using Iodine(III) Reagents
Authors: Jin Li‐Mei , Chen Liang , Yin Juan‐Juan , Guo Can‐Cheng , Chen Qing‐Yun 
Published: August 2005

AbstractThe synthesis of meso,meso‐linked fluoroalkylporphyrin arrays has been accomplished, in excellent yields, by the simple treatment of a CHCl3 solution of zincated 5‐fluoroalkyl‐10,20‐diarylporphyrins (where fluoroalkyl = CF3, ClC2F4, n‐ClC4F8, n‐C6F13, etc.) with iodine(III) reagents such as PhI(O–CO–CF3)2 (PIFA, also named as bis(trifluoroacetoxy)iodo]benzene) or PhI(OAc)2 (PIDA). For nonfluorinated zincated 5‐substituted‐10–20‐diarylporphyrins (where substituent = phenyl, 4‐methoxyphenyl, 4‐methylphenyl, etc.) the similar coupling reactions also proceed fast and quantitatively. Moreover, various 15‐unsubstituted metalloporphyrins can also be coupled in high yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
New Oblongolides Isolated from the Endophytic Fungus Phomopsis sp. from Melilotus dentata from the Shores of the Baltic Sea
Authors: Dai Jingqiu , Krohn Karsten , Gehle Dietmar , Kock Ines , Flörke Ulrich , Aust Hans‐Jürgen , Draeger Siegfried , Schulz Barbara , Rheinheimer Joachim 
Published: August 2005

AbstractThirteen new metabolites, namely oblongolides B–M (2–13) and 4‐[5‐(1‐hydroxyethyl)furan‐2‐yl]‐4‐oxobutanoic acid (14), together with the six known compounds phomopsolide B (15), alternariol dimethyl ether (16), alternariol monomethyl ether (17), the mycotoxin alternariol (18), ergosterol (19), and 5α,8α‐epidioxyergosterol (20) were isolated from the endophytic fungus Phomopsis sp. The new biologically active norsesquiterpene γ‐lactones differ in their degree of substitution, saturation, and substituent pattern from the known oblongolide 1. Their structures were determined by means of spectroscopic data including HREIMS, 1H NMR, 13C NMR, 2D NMR (HMQC, HMBC, NOESY) and X‐ray single crystal analysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Regioselective and Divergent Opening of Vinyl Epoxides with Alkyne Nucleophiles
Authors: Restorp Per , Somfai Peter 
Published: August 2005

AbstractA divergent procedure for nucleophilic ring‐opening of vinyl epoxides with alkynes has been developed. The combination of lithium acetylides and BF3·OEt2 afforded the SN2 products, whereas alkynylalanes gave SN2′ addition. The regioselectivity of these processes is affected by the alkyne substituent. Ethoxyacetylene added with complete regiocontrol under both SN2 and SN2′ conditions, and the SN2 isomeric adducts could be rearranged into γ‐butyrolactones. The synthetic utility of the process is demonstrated by a short synthesis of γ‐butyrolactone 24, a key intermediate in the synthesis of prostaglandin PGF2α. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Investigation of solvent effects in capillary electrophoresis for the separation of biological porphyrin methyl esters
Authors: Li Qi , Chang Chi K. , Huie Carmen W. 
Published: August 2005

AbstractThe effects of organic solvents on the capillary electrophoresis (CE) separation of a number of important biological porphyrin methyl esters – six weakly basic, hydrophobic cyclic tetrapyrroles possessing two and four to eight methyl ester groups around the periphery of the porphyrin ring – were investigated in the mode of micellar electrokinetic chromatography (MEKC), microemulsion electrokinetic chromatography (MEEKC), and nonaqueous CE. In aqueous MEKC, partial separation of the six neutral porphyrin methyl esters was obtained with an organic modifier (acetonitrile) in the concentration range between 20 and 40%, in which sodium dodecyl sulfate (SDS) molecules might be present in the form of SDS micelles and/or SDS micelle‐like aggregates. Relatively stable SDS micelles can be formed in nonaqueous MEKC using formamide as the separation medium, but the separation of the target analytes remained unsatisfactory. Improved resolution of all six porphyrin methyl esters was obtained using MEEKC with the running buffer consisting of 0.8% w/w n‐heptane (oil phase), 2.25% w/w SDS and 1.0% w/w Brij 35 (mixed surfactant), 6.6% w/w 1‐butanol (cosurfactant), and 30% v/v 2‐propanol (second cosurfactant), but reproducibility in terms of peak areas for certain porphyrins (especially uroporphyrin I octamethyl ester) was found to be very poor. Best separation performances were achieved with nonaqueous CE separations in which the weakly basic porphyrin methyl esters were protonated under strongly acidic conditions (e.g., using 10 mM perchloric acid) in mixed organic solvents. For example, using a 50:50 mixture of methanol and acetonitrile as the separation medium, baseline separation of all six (positively charged) porphyrin methyl esters can be obtained within 3 min and the average precision (RSD, N = 13) in terms of migration time and peak area were 0.55 and 2.16%, respectively.
Nonaqueous capillary electrophoresis in coated capillaries: An interesting alternative for proteomic applications
Authors: Assunção Nilson A. , Deziderio Leandro A. Grange , Paulino Luis G. , Lupetti Karina O. , Carrilho Emanuel 
Published: August 2005

AbstractThis work brings together some contributions for the use of nonaqueous media for proteomic analysis, for both capillary electrophoresis (CE) separation and the preparation of tryptic digests. First, a ternary nonaqueous buffer consisting of 60/30/10 v/v methanol/acetonitrile/acetic acid with 12.5 mmol/L ammonium acetate was optimized for CE separation of the tryptic digest of lysozyme. Lysozyme was chosen as a model system for the protein digestion, which has also been prepared in an organic‐rich medium with methanol/50 mmol/L NH4HCO3, pH 8.0 (60/40 v/v). The separation results were compared to in silico (PeptideCutter program) digestion conditions, and high‐efficiency peak separation (18 peaks) was obtained in 20 min with an electric field of 350 V/cm. In addition, we have evaluated the stability of a coated capillary with poly‐N,N‐dimethylacrylamide (60/30 cm total/effective length and 75 μm ID) for over 100 runs of tryptic digest with the nonaqueous background electrolyte solvent system. The migration times for ten selected peptide peaks presented 3–7% relative standard deviation.
Age effects on diffusion tensor magnetic resonance imaging tractography measures of frontal cortex connections in schizophrenia
Authors: Jones Derek K. , Catani Marco , Pierpaoli Carlo , Reeves Suzanne J.C. , Shergill Sukhwinder S. , O'Sullivan Michael , Golesworthy Pasha , McGuire Phillip , Horsfield Mark A. , Simmons Andrew , Williams Steven C.R. , Howard Robert J. 
Published: August 2005

AbstractDiffusion tensor magnetic resonance imaging (DT‐MRI) has previously been used to investigate white matter tracts in schizophrenia, with inconsistent results. The aim of the study was to use a novel method for tract‐specific measurements of fronto‐temporal fasciculi in early‐onset schizophrenia. We hypothesized that by making tract‐specific measurements, clear diffusion abnormalities would be revealed in specific fasciculi in schizophrenia. Measurements of diffusion anisotropy and mean diffusivity were localized within fronto‐temporal fasciculi by forming 3‐D reconstructions of the cingulum, uncinate, superior longitudinal, and inferior fronto‐occipital fasciculi using diffusion tensor tractography. We were limited in our ability to test our hypothesis by the important and surprising finding that age affected DT‐MRI‐based measures in schizophrenia patients in a different way from comparison subjects, most notably in the left superior longitudinal fasciculus. The youngest schizophrenia patients that we studied had lower diffusion anisotropy than age‐matched comparison subjects, but this difference diminished with increasing age. The main conclusion of this study was that direct comparisons of absolute DT‐MRI‐based measures between individuals with schizophrenia and comparison subjects may be problematic and misleading because of underlying age‐related differences in brain maturation between groups. Hum Brain Mapp, 2005. © 2005 Wiley‐Liss, Inc.
Impact of organizational change on the delivery of reproductive services: a review of the literature
Authors: Ensor Tim , Ronoh Jeptepkeny 
Published: August 2005

AbstractIn order to understand the impact of specific maternal health interventions, it is necessary to understand the likely effect of the health system structure. An important aspect of this structure is the organizational culture. Many systems in low‐income countries have been based on a centrally planned and financed system. In recent years a series of organizational changes have been introduced into many systems and these substantially alter the way in which the system operates and impacts on reproductive health care provision. The main changes reviewed in this paper are: (i) decentralization, (ii) privatization and (iii) integration and sector wide approaches. Each of these changes is seen to have important implications for reproductive health. In each case it is clear that the nature of the impact depends crucially on the way it is implemented. Quantifying the impact of these changes remains extremely difficult given the many different ways they can be introduced and the many confounding factors that affect the overall impact. The literature does, however, point to a number of key issues that impinge on the way in which change is likely to affect reproductive health initiatives. Copyright © 2005 John Wiley & Sons, Ltd.
Transferable learning from international primary care developments
Authors: Meads Geoffrey , Iwami Michiyo , Wild Andrea 
Published: August 2005

AbstractAlternative approaches to the comparative analysis of international health systems developments are reviewed in relation to the advent of new primary care organizations in countries with parallel ‘modernizing’ policies. A framework for transferable learning between these is articulated and its design described. This is derived from priorities defined by lead policy and practice representatives in UK primary care. It points to the benefits of examining the interaction of critical new public management and planning functions as an effective vehicle for identifying both individual country role models and shared international experiences. Illustrative examples are provided in five subject areas ranging from local engagement to multiple forms of financing. Copyright © 2005 John Wiley & Sons, Ltd.
Identification and thermodynamic treatment of several types of large‐amplitude motions
Authors: Katzer Gernot , Sax Alexander F. 
Published: August 2005

AbstractWe present a partially automated method for the thermodynamic treatment of large‐amplitude motions. Starting from the molecular geometry and the Hessian matrix, we evaluate anharmonic partition functions for selected vibrational degrees of freedom. Supported anharmonic vibration types are internal rotation and inversion (oscillation in a double‐well potential). By heuristic algorithms, we identify internal rotations in most cases automatically from the Hessian eigenvectors, and we also estimate the parameters of anharmonic partition functions (e.g., potential barrier, periodicity, and symmetry number) with thermodynamically sufficient precision. We demonstrate the validity of our schemes by comparison to pointwise calculated ab initio potential curves. © 2005 Wiley Periodicals, Inc. J Comput Chem 14: 1438–1451, 2005
Coupling of the Polymer Threading a Membrane Transition to the Membrane Adsorption Transition
Authors: Di Marzio Edmund A. , Guttman Charles M. 
Published: August 2005

AbstractA polymer molecule threading through a pore in a plane membrane is allowed to adsorb on either or both sides of the membrane. Further, it is confined to the vicinity of the membrane by two plane barriers lying on either side of the membrane. A lattice model of this problem is exactly solvable by matrix techniques. The equilibrium translocation behavior is described as a function of the polymer MW, the membrane adsorption energies, the solution properties, the barrier separations, applied force, and the temperature. The transition is first‐order, meaning that small changes in any of these 9 quantities can in the limit of infinite MW, completely translocate the polymer. The work of Park and Sung who used Smoluchowski‐like equations to calculate translocation transit times can be generalized by use of the sea‐snake model which is relevant to isolated polymer chains in solution. The physics behind the sea‐snake model is that if one monomer is pulled into the membrane, the distance the center of mass of the untranslocated portion of the chain moves is MW−1/2 of the distance between monomer units. This reduces the effective friction coefficient by MW1/2. It is found for the sea‐snake model that the MW dependence of transit times varies as MW3/2 or MW depending on whether we use a free draining or a non‐free draining picture for the polymer.
Toward a Constitutive Law of Cartilage: A Polymer Physics Perspective
Authors: Basser Peter J. , Horkay Ferenc 
Published: August 2005

AbstractTo describe load bearing and lubrication of cartilage requires treating its collagen network and proteoglycan (PG) phases separately in a constitutive law of the tissue. We propose a framework for developing such an empirical constitutive law that treats the cartilage extracellular matrix (ECM) as a composite medium, with a PG phase that exerts a swelling pressure, and a collagen network phase that restrains it. We compare and contrast this model to a biomechanical constitutive law that aggregates the collagen and PG phases into a single “solid‐like” elastic tissue matrix, and show that aggregation obscures essential differences in the physical‐chemical properties of the collagen and PG constituents as well as their distinct biological roles within cartilage's ECM. We also relate moduli in the aggregate constitutive model to quantities measured in an osmotic stress titration experiment.
Manipulation of Polymer Chain Entanglement and Self‐Assembly for DNA Capillary Electrophoresis
Authors: Chu Benjamin , Ying Qicong , Wang Yanmei , Zhang Jun 
Published: August 2005

AbstractA conceptual model has been developed and tested experimentally on five different aspects, relating to the architecture and topology of the polymers making up the transient network that constitutes the separation matrix. The concept can be applied for DNA sequencing analysis and separations of short fragments double‐stranded DNA as well as oligonucleotides. Examples are provided to illustrate the success of the concept.
Modeling Ca‐Polyanion Crosslinking in Secretory Networks. Assessment of Charge Density and Bond Affinity in Polyanionic Secretory Networks
Authors: Chin Wei‐Chun , Quezada Ivan , Steed Jordan , Verdugo Pedro 
Published: August 2005

AbstractMaterials released by secretory cells are stored inside intracellular membrane‐bound vesicles. These moieties are not freely diffusible in the vesicle but remain immobilized in a Ca2+‐crosslinked condensed‐phase polyanionic polymer matrix. During exocytosis a Na+/Ca2+ ion exchange process triggers a volume phase transition resulting in massive swelling and release of the materials to the extracellular space. Here we formulate a simple model to assess Ca2+‐ion binding from the swelling kinetics of polymer networks. We found the diffusivity of the networks (D) exhibits a power‐law dependency on the Ca2+ concentration where D ∝ [Ca2+]−2/3. The model yields an estimate of charge density and ionic affinity of the polymer chains. Studies of post‐exocytic swelling kinetics in airway mucin granules, mast cell granules and granules from the microalga (Phaeocystis globosa) were used to validate predictions from our model. These results suggest that independent of the cell type, from animal to plant cells, a single polyelectrolyte interaction mechanism appear to be responsible for product release in exocytosis.
Abrupt Structural Changes in Polyanionic Gels Evoked by Na‐Ca Ion Exchange: Their Biological Implications
Authors: Tasaki Ichiji 
Published: August 2005

AbstractAnionic polyelectrolyte gels, synthetic or natural, undergo abrupt structural changes when the monovalent counterions in the gel, e.g., Na+, are replaced with divalent cations, e.g., Ca2+. These structural changes are caused by the preferential binding of Ca2+ to the polyelectrolyte chains and the ability of Ca2+ to form crosslinks between two neighboring chains. Strong lyotropic (Hofmeister) effects of anions, such as fluoride, phosphate, aspartate and chloride, on the repetitiveness of abrupt structural changes in the gel strands are demonstrated. These findings have important biological implications.
Development of Liquid Crystalline Order During Cure of Mesogenic Epoxy Resins
Authors: Mossety‐Leszczak Beata , Włodarska Magdalena , Galina Henryk , Bąk G.W. , Pakula Tadeusz 
Published: August 2005

AbstractIn the present paper we describe the curing process of a new liquid crystalline epoxy monomer with 4,4′‐diaminodiphenylenemethane (DDM). The characteristic of cured product is presented. Both the monomer and cured product have been characterized by IR and NMR spectroscopy, differential scanning calorimetry (DSC), polarized optical microscopy (POM), wide‐angle X‐ray scattering (WAXS) and dielectric relaxation spectroscopy (DRS).The curing process was analysed with the use of DSC and real‐time DRS.
Chemically and Physically Induced (Reversible) Gelation of Organic Liquids by Monomeric and Polymeric Gelators
Authors: George Mathew , Luo Chuping , Wang Caihua , Carretti Emiliano , Dei Luigi , Weiss Richard G. 
Published: August 2005

AbstractThe properties of several types of organogels that can undergo a chemical transition during gelation or while in the gel phase are described. The transitions can be physically induced by light or chemically triggered by the addition of an acid or a neutral molecule such as CO2 or CS2. In some cases, the gelation properties of the new species formed are markedly different from those of the precursors. The link between molecular structure and the nature of the gel networks as well as results obtained from the multidisciplinary tools used to study them are discussed.
Three‐Dimensional Collagen Gel Networks for Neural Stem Cell‐Based Neural Tissue Engineering
Authors: Ma Wu , Chen Silvia , Fitzgerald Wendy , Maric Dragan , Lin Hsingch J. , O'Shaughnessy Thomas J. , Kelly Jeremy , Liu Xiu‐Huai , Barker Jeffery L. 
Published: August 2005

AbstractStem and progenitor cells isolated from the embryonic rat cerebral cortex were immobilized by matrix entrapment in three‐dimensional (3D) Type I collagen gels, and cultured in serum‐free medium containing basic fibroblast growth factor. The cells trapped within the collagen networks actively proliferated and formed clone‐like aggregates. Neurons were the first differentiated cells to appear within the aggregates, followed by generation of astrocytes and oligodendrocytes. In addition, necrotic cores were developed as the aggregate diameter increased and cell viability declined significantly after 3 weeks in culture. To overcome these problems, the cell‐collagen constructs were transferred to Rotary Wall Vessel bioreactors for up to 10 weeks. In the rotary culture, the collagen gels compacted 3‐4 folds and a long‐term growth and differentiation of neural stem and progenitor cells was dynamically maintained. Remarkably, the cell‐collagen constructs formed a complex two‐layered structure that superficially emulated to a certain extent the cerebral cortex of the embryonic brain in architecture and functionality. The engineered 3D tissue‐like constructs displaying characteristic properties of neuronal circuits may have potential use in tissue replacement therapy for injured brain and spinal cord.
Multi‐Material Scaffolds for Tissue Engineering
Authors: Darling Andrew , Shor Lauren , Khalil Saif , Mondrinos Mark , Lelkes Peter , Guceri Selcuk , Sun Wei 
Published: August 2005

AbstractA trend in developing biocompatible scaffolds for tissue engineering has been to seek an ideal single material for which a given cell type will exhibit favorable behavior. While an ideal single material has proven elusive, scaffold manufacture using combinations of specialist materials can produce more versatile structures. By controlling the percentage and architecture of material components, mechanical properties, cell attachment, and proliferation may be optimized for a given function. Three specialist materials, poly‐ϵ‐caprolactone (PCL), fibrin, and alginate, were incorporated into multi‐component scaffolds for a series of experiments testing each component with culture of fibroblasts. The rigid and formable PCL provided structure, the fibrin pore‐filler allowed for cell attachment, and alginate thread provided a nutrient transfer pathway in lieu of a vascular system. The efficacy of these scaffolds was judged on fibroblast distribution and population after 7‐12 days of culture.