bluuebunny/crossref_metadata_2025_split huggingface dataset:
Highly Fluorinated Poly(arylene ether ketone) Prepared by a CaH2‐Mediated Polycondensation Reaction
Authors: Ding Jianfu , Day Michael , Robertson Gilles P. , Roovers Jacques 
Published: May 2004

AbstractSummary: A new reaction procedure has been developed for the polycondensation of hexafluorobisphenol A (6F‐BPA) with bis(pentafluorophenyl) ketone (BPK) in dimethylacetamide (DMAc). In this reaction, CaH2 has been used as a base to facilitate the formation of the phenolate; an alkali metal fluoride was used as a catalyst. Unlike the conventional polycondensation reactions, this procedure avoided producing water during the reaction, and hence, azeotropic distillation with the assistant of a low‐polar co‐solvent is not required. This improvement maintains the high polarity of the reaction medium; consequently, the selectivity of the reaction at the para‐position of BPK is significantly enhanced and polymers with high molecular weights ($\overline M _{\rm n}$ ca. 30 000 Da) can be obtained with very low branching contents (less than 3 mol‐%) and free of any cross‐linked gel particles. In addition to avoiding the formation of water in the reaction, the use of CaH2 also reduced the concentration of the fluoride ion in the solution. These effects minimize chain degradation reactions such as hydrolysis. The use of CaO instead of CaH2 for this reaction produces similar effects. In the case of CaO, traces of water can be introduced into the reaction. The presence of trace amounts of water increases the polycondensation rate, probably due to the enhanced ionization of the phenolate. However, it also causes a hydrolysis of polymer chains, resulting in the elimination of the ketone group in the polymer backbone. Fortunately, this side reaction is highly water and temperature dependent, and can be efficiently prevented by using CaH2 or conducting the reaction at a lower temperature (<65 °C).CaH2‐mediated polycondensation for the preparation of highly fluorinated poly(arylene ether ketone).imageCaH2‐mediated polycondensation for the preparation of highly fluorinated poly(arylene ether ketone).
Exact solutions of space–time dependent non‐linear Schrödinger equations
Authors: Ruan Hang‐yu , Li Hui‐jun , Chen Yi‐xin 
Published: May 2004

AbstractUsing a general symmetry approach we establish transformations between different non‐linear space–time dependent evolution equations of Schrödinger type and their respective solutions. As a special case we study the transformation of the standard non‐linear Schrödinger equation (NLS)‐equation to a NLS‐equation with a dispersion coefficient which decreases exponentially with increasing distance along the fiber. By this transformation we construct from well known solutions of the standard NLS‐equation some new exact solutions of the NLS‐equation with dispersion. Copyright 2004 John Wiley & Sons, Ltd.
Exact controllability for quasilinear hyperbolic systems and its application to unsteady flows in a network of open canals
Authors: Tatsien Li 
Published: May 2004

AbstractIn this paper we establish the exact boundary controllability for quasilinear hyperbolic systems with interface conditions. As an application, we get the exact boundary controllability of unsteady flows in a string‐like network of open canals. Copyright © 2004 John Wiley & Sons, Ltd.
On the existence of steady flows of a Navier–Stokes liquid around a moving rigid body
Authors: Silvestre Ana Leonor 
Published: May 2004

AbstractWe prove the existence of a strong solution to the three‐dimensional steady Navier–Stokes equations in the exterior of an obstacle undergoing a rigid motion. Unlike the classical exterior problem for the Navier–Stokes equations, that only takes into account the translational motion of the obstacle, is this case, the obstacle can also rotate. Assuming the total flux of the velocity field through the boundary to be sufficiently small, we first construct approximating solutions in bounded regions ΩR = Ω∩ {x ∈ ℝ3:∣x∣< R} invading the liquid domain Ω. A set of estimates independent of R are shown to hold for the approximating solutions which allows to obtain a strong solution by taking the limit R→∞. Copyright © 2004 John Wiley & Sons, Ltd.
On a resolvent problem for the linearized system from the dynamical system describing the compressible viscous fluid motion
Authors: Shibata Yoshihiro , Tanaka Koumei 
Published: May 2004

AbstractThe linearized initial boundary value problem describing the motion of the viscous compressible fluid is studied under Dirichlet zero condition in bounded and unbounded domains. The resolvent estimate for the corresponding operator is proved in the Lp framework and the sharp inner estimate of the resolvent set is obtained. Copyright © 2004 John Wiley Sons, Ltd.
1‐(2‐pyrimidinyl)‐piperazine, a buspirone metabolite, modulates bladder function in the anesthetized rat
Authors: Myers Robert A. , Plym Mary Jane , Signor Laura J. , Lodge Nicholas J. 
Published: May 2004

AbstractAimsTo examine the effects of 1‐(2‐pyrimidinyl)‐piperazine (1‐PP), a buspirone metabolite, on bladder function in vivo.MethodsMicturition reflexes in the rat were evaluated in two models of bladder function; a constant infusion model employing 0.5% acetic acid and an isovolumic model.ResultsIn the constant infusion model, 1‐PP (0.14–1.32 mg/kg) dose‐dependently and significantly decreased the number of bladder contractions measured during a 30 min recording period, with little effect on the pressure developed during each contraction. 1‐PP is an α2‐adrenergic receptor antagonist. The α2 antagonists BRL44408 (α2A vs. α2B selective; 0.3 and 1 mg/kg), imiloxan (α2B vs. α2A selective; 1 mg/kg), and yohimbine (non‐subtype selective; 1 mg/kg; but not 0.3 mg/kg) also significantly reduced the number of contractions. Vehicle was without effect. In the isovolumic model, 1‐PP (0.03–1.0 mg/kg) produced a dose‐dependent and significant reduction in the number of bladder contractions recorded during a 15 min assessment period, with the maximum effect observed at 0.3 mg/kg. 1‐PP had little effect on blood pressure; the only effect was observed at the highest dose (1 mg/kg) where it produced a transient 17% decrease in pressure. Cromakalim and tolterodine served as comparitors in all studies.Conclusions1‐PP decreased the number of bladder contractions evoked by the micturition reflex at doses that had little effect on either the pressure developed during each bladd er contraction or on blood pressure. The effects of 1‐PP are likely mediated primarily by α2 receptor antagonism. © 2004 Wiley‐Liss, Inc.
Some recent contributions to network optimization
Authors: Ben‐Ameur Walid , Gouveia Luis 
Published: May 2004

AbstractThis report highlights some recent contributions to network optimization based on papers presented at the first International Network Optimization Conference (INOC'2003) held in Evry‐Paris, France. © 2004 Wiley Periodicals, Inc. NETWORKS, Vol. 44(1), 27–30 2004
Neighborhood associations and urban decision making in Albuquerque
Authors: King Karen N. 
Published: May 2004

AbstractNeighborhood associations have the potential to be important players in the urban decision‐making process. There are numerous examples of situations in which they have exercised their unique capabilities to influence decisions that have a direct impact on their members. But their role in the larger arena of the city they inhabit is less clear. This study explores the degree to which neighborhood associations, through their newsletters, acknowledge and support citywide goals. A content analysis of 173 newsletters from forty‐four neighborhood associations in Albuquerque, New Mexico, revealed that they do provide some support for several citywide goals but not for the majority of them.
Episcleral plaque brachytherapy for retinoblastoma
Authors: Merchant Thomas E. , Gould Ciara J. , Wilson Matthew W. , Hilton Nathan E. , Rodriguez‐Galindo Carlos , Haik Barrett G. 
Published: May 2004

AbstractBackgroundThe purpose of this study was to report our experience using episcleral plaque brachytherapy (EPBRT) to treat retinoblastoma and to demonstrate its applicability in multimodality treatment.ProcedureWe treated 26 tumors in 25 eyes from a group of 21 children with unilateral (n = 4) or bilateral (n = 17) retinoblastoma. The group comprised 8 girls and 13 boys; the median age was 25 months (range: 2–64 months) at the time of EPBRT. Iodine‐125 (125I) was used for all applications. The median dose was 44 Gy (range: 35–47.6 Gy). EPBRT was administered primarily at the time of relapse after primary chemotherapy or radiation therapy.ResultsFor eyes treated with EPBRT, the eye preservation rate was 15/25 with a median follow‐up of 47 months (range: 2–198 months); the lesion control rate was 25/26 with a median follow‐up of 13 months (range: 1–140 months). The median time to additional whole‐eye treatment after EPBRT was 12 months (range: 2–105 months).ConclusionsSimilar to previously reported series, EPBRT shows a high rate of successful tumor control as a primary treatment for retinoblastoma, as well as a secondary therapy at the time of relapse. EPBRT also allows for a clinically significant delay in the time to additional measures for the affected eye. Therefore, EPBRT should be considered as a form of local ophthalmic therapy that avoids or delays the use of external‐beam radiotherapy, especially for patients primarily treated with chemotherapy who might require consolidation therapy.© 2004 Wiley‐Liss, Inc.
Challenges to the measurement of health‐related quality of life in children receiving cancer therapy
Authors: Nathan Paul C. , Furlong William , Barr Ronald D. 
Published: May 2004

AbstractMeasures of health‐related quality of life (HRQL) assess those areas of a patient's functioning that are affected by their cancer and its therapy. Although HRQL measures are integrated frequently into studies of survivors of childhood cancer, their use in the assessment of children receiving therapy has been limited by several methodological challenges. These arise from issues specific to measuring HRQL in young children, who comprise a large proportion of the pediatric oncology population, and from issues associated with assessing HRQL during therapy, when the patient's health status is in constant flux. This study summarizes the commonly used HRQL measures, and examines factors that impact their broad application. These include the influence of developmental changes on the content and format of HRQL measures, the role of proxy assessors, the important characteristics of measurement tools used to assess patients receiving active therapy, and the issues related to the ideal timing of serial HRQL assessments in prospective trials. © 2004 Wiley‐Liss, Inc.
Tactile massage improves glycaemic control in women with type 2 diabetes: a pilot study
Authors: Andersson K , Wändell P , Törnkvist L 
Published: May 2004

AbstractThe purpose of this study was to investigate how tactile massage (TM), short term and over time, affects blood glucose, stress hormones and well‐being in women with type 2 diabetes mellitus, at a primary health care centre in the South Western Health Care Region of Stockholm.The study was carried out as a pilot. Women aged 35 years and older with type 2 diabetes were included in the study. Eleven participants completed the study and eight patients retained their diabetes treatment. The patients received tactile, whole‐body massage for 60 minutes once a week for 10 weeks. Before the massage treatments, one week after and 12 weeks after that, blood samples were taken, body measurements were made and questionnaires were completed (n=11).The results for all patients (n=11) showed decreases in blood glucose in connection with the massage treatments (p<0.05). In addition, the results for these patients showed a significant reduction of B‐HbA1c from measurement before the massage treatments, mean 6.3, one week after finishing the massage treatments, mean 5.4 (p<0.01), and 12 weeks after the massage treatments, mean 5.4 (p<0.05). This was also found when the three patients who had their medication changed (because of the risk of hypoglycaemia) were excluded (p<0.05). No statistically significant differences were found regarding the hormones oxytocin, CRF )cortico‐releasing hormone) and ACTH (adenocorticotrophin hormone).This study is the first of its kind to show improved metabolic control (B‐HbA1c) in diabetic patients who have received TM. Although theories have been put forward, the mechanisms behind this change are unclear. Copyright © 2004 John Wiley & Sons, Ltd.
Fast fragmentation and slow protonation: a buffer‐dependent isotope effect in reactions of N‐methyl hydroxy(benzylthiamine) analyzed by the Keeffe–Jencks equations
Authors: Ikeda Glenn , Kluger Ronald 
Published: May 2004

AbstractThe fragmentation of 2‐(1‐hydroxybenzyl)thiamine in neutral solution (to cleave the pyrimidine and thiazolium) has been shown to compete very effectively with elimination of benzaldehyde to produce thiamine in neutral solution. The fragmentation is believed to involve protonation competing with C—N bond cleavage in the C2α conjugate base as a rate‐determining step. We report that proton removal from C2α of N1′‐methyl‐2‐(1‐hydroxybenzyl)thiamine (MHBnT) is rate‐limiting in low concentrations of pH 6 phosphate buffer: reprotonation competes with the subsequent fragmentation step (cleaving the pyrimidine–thiazolium bridge derived from thiamine) at higher buffer concentrations. Comparison of the observed rates of reaction of protio and C2α‐deutero MHBnT reveals a non‐linear variation of the kinetic isotope effect that fits precisely to a ratio derived from the Keeffe–Jencks rate law formulation for E1CB reactions. The fragmentation step is clearly distinct from the proton removal step and the isotope sensitivity is limited to the initial step. The variation of the isotope effect is a result of changes due to differing contributions from the hydroxide and buffer‐catalyzed reaction mechanisms. Copyright © 2004 John Wiley & Sons, Ltd.
Transition‐state responses to amino acid perturbations in yeast pyruvate decarboxylase: a carbon kinetic isotope effect study
Authors: Chen Lan , Yuan Yang , Huskey W. Phillip 
Published: May 2004

AbstractCarbon kinetic isotope effects (12C/13C at the carboxyl carbon of pyruvic acid) and their pH dependence were measured for the decarboxylation reaction catalyzed by the substrateregulated yeast pyruvate decarboxylase (PDC) and several of its site‐specific variants. The active‐site variants studied were E477Q, D28A and E51D; the regulatory‐site variants, each with two amino acid substitutions, were C221A/C222A, C221E/C222A and C221D/C222A. The isotope effects for the regulatory‐site variants were not significantly different from the values for the wild‐type enzyme (1.0046 ± 0.0003 at pH 6.0, 25°C). For the active‐site variants, the isotope effects were 1.0018 ± 0.0009 (E477Q), 1.0398 ± 0.0021 (D28A) and 1.0143 ± 0.0011 (E51D) at pH 6.0 and 25°C. The results were interpreted in terms of shifts in the rate‐limiting steps and uniform binding changes in the free‐energy profiles for decarboxylation phase of the PDC reaction. Copyright © 2004 John Wiley & Sons, Ltd.
Aqueous methanolysis of an α‐D‐N‐acetylneuraminyl pyridinium zwitterion: solvolysis occurs with no intramolecular participation of the anomeric carboxylate group
Authors: Knoll Tara L. , Bennet Andrew J. 
Published: May 2004

AbstractThe synthesis of 3,4‐dihydro‐2H‐pyrano[3,2‐c]pyridinium α‐D‐N‐acetylneuraminoate (4), the subsequent rate constants for aqueous methanolysis and the associated reaction products are reported. When compared with the analogous 2‐deoxyglucopyranosyl 4′‐bromoisoquinolinium salt (11), the rate of solvolysis of 4 displays a reduced sensitivity towards the ionizing power of the solvent. Solvolysis product analysis showed that substitution occurs predominantly with inversion of configuration. Hence it can be concluded that the methanolysis reactions of 4 proceed via dissociative transition states with no intramolecular nucleophilic participation by the anomeric carboxylate group. Copyright © 2004 John Wiley & Sons, Ltd.
Stereochemistry and secondary reactions in the irreversible inhibition of serine hydrolases by organophosphorus compounds
Authors: Kovach Ildiko M. 
Published: May 2004

AbstractThe stereoselectivity of phosphonylation of serine hydrolases by the ROR′P(O)X group of compounds is governed by the electronic properties of X, the size of RO groups, the active site milieu and the specific architecture of the active site of the serine hydrolase. For example, stereoselectivity in excess of 104 has been observed favoring the P(S) diastereomers of 2‐(3,3‐dimethylbutyl) methylphosphonofluoridate (soman) when phosphonylating acetylcholinesterases. Based on molecular dynamics simulations, this is attributable to specific binding of the pinacolyl group to Glu199, Trp84 and Phe331, which exert compression to effect F− departure in the pentacoordinate transient (transition state or intermediate) of soman‐inhibited cholinesterases. The pinacolyl group is not so well adapted at the acyl‐binding site in the P(R) diastereomers reducing the efficiency of F− expulsion. Serine hydrolase inactivation is often followed by secondary reactions. The electronic properties of ligands attached to P are decisive in whether CO or PO bond cleavage occurs in phosphonate diesters of serine hydrolases. Phenoxide ions leave readily with PO cleavage from cholinesterases and chymotrypsin, the reaction resembling deacylation in the reaction of substrates. The architecture and electrostatic character of the active site govern the fate of a covalently attached phosphonyl fragment. Strong negative electrostatic and hydrophobic forces in the cholinesterases preferentially promote CO bond cleavage with occasional methyl migration, whereas this route of dealkylation is nearly absent in phosphonate esters of serine proteases. Dealkylation in soman‐inhibited cholinesterases is 10 orders of magnitude faster than in appropriate model reactions and occurs 104 times faster in the P(S) than in the P(R) diastereomers. It is driven by enzyme‐facilitated methyl migration, occurring most likely concerted with CO bond cleavage. Copyright © 2004 John Wiley & Sons, Ltd.
Isergonic relationship in the acid‐catalyzed hydrolysis of carboxylic esters with hydrogen‐bonding capability
Authors: Mata‐Segreda Julio F. 
Published: May 2004

AbstractThe average value of the enthalpies of activation for the acid‐catalyzed hydrolyses of ethyl 2‐hydroxypropanoate and five acetate esters with hydrogen bonding capability is 57±7 kJ mol−1 (p = 0.05). This value is 11 kJ mol−1 lower than the mean observed for primary and secondary alkyl acetates and ethyl alkanoates, measured in water and in mixtures of water with organic solvent with high water content. The difference is attributed to tighter transition‐state complex hydration via hydrogen bonding, relative to reactant ester species. Enthalpy–entropy compensation with an isokinetic temperature of 346 K was found to be valid at p<0.05, a value typical for solvent‐mediated kinetic effects. Copyright © 2004 John Wiley & Sons, Ltd.
meso‐Tetratolylporphyrins substituted by pyridinium groups: aggregation, photophysical properties and complexation with DNA
Authors: Procházková K. , Zelinger Z. , Lang K. , Kubát P. 
Published: May 2004

AbstractThe aggregation behavior, binding to DNA and photophysical properties of meso‐tetratolylporphyrins substituted with two (P2), three (P3) and four (P4) pyridinium groups were studied using UV–visible and transient spectroscopy, resonance light scattering, circular dichroism and time‐resolved luminescence of singlet oxygen. In aqueous solutions porphyrins P2–P4 were present as monomers and aggregates of H‐ and J‐type. The concentration ratio of monomer to aggregates was controlled by the number of cationic substituents, by ionic strength and by temperature. Porphyrin P4 was predominantly monomeric and was externally bound to calf thymus DNA with a binding constant of 1.2 × 106 M−1. Porphyrins P3 and P2 self‐assembled on the DNA backbone to form chiral assemblies not affecting the duplex melting point. The lifetimes of the triplet states of monomeric P3 and P4 increased after binding to DNA; however, this did not prevent the formation of singlet oxygen, 1O2. Copyright © 2004 John Wiley & Sons, Ltd.
Sampling Issues in Assessing Particle Degradation in Pneumatic Conveying Systems
Authors: Abou‐Chakra Hadi , Chapelle Pierre , Tüzün Ugur , Baxter John , Patel Mayur , Cross Mark , Bridle Ian , Bradley Michael S. A. 
Published: May 2004

AbstractThe evaluation or design of a granular material handling process requires reliable data if executive decisions are to be made. Material behavior in a given process is usually investigated by collecting and analyzing material samples from different locations within the system. However, sampling can be a significant source of errors, as a poor sampling method can lead to measurements not truly representative of the real process.
Visualizing complexes of phospholipids with Streptomyces phospholipase D by automated docking
Authors: Aikens Christopher L. , Laederach Alain , Reilly Peter J. 
Published: May 2004

AbstractThe automated docking program AutoDock was used to dock nine phosphatidic acids (PAs), six phosphatidylcholines, five phosphatidylethanolamines, four phosphatidylglycerols, one phosphatidylinositol and two phosphatidylserines, which have two identical saturated fatty acid residues with an even numbers of carbon atoms, onto the active site of Streptomyces sp. PMF phospholipase D (PLD). Two PAs with one double bond on the fatty acid chain linked to the C2 of the glycerol residue were also docked. In general, binding energies become progressively more negative as fatty acid residues become longer. When these residues are of sufficient length, one is coiled against a hydrophobic cliff in a well that also holds the glycerol and phosphate residues and the head group, while the other generally is bound by a hydrophobic surface outside the well. Phosphatidylcholines have the only head group that is firmly bound by the active site, giving a possible structural explanation for the low selectivity of Streptomyces PLD for other phospholipid substrates. Proteins 2004. © 2004 Wiley‐Liss, Inc.
The new EU Clinical Trials Directive and Orphan Medicinal Products: current status and recommendations
Authors: Tambuyzer Erik , Mooney Paul , Incerti Carlo 
Published: May 2004

AbstractThe European Union (EU) ‘Clinical Trials’ directive will be implemented in all EU member states in May 2004 and will have a significant impact on clinical research in the EU. Its advent has caused a stir amongst commercial companies and academics alike and many even argue that it should not lead to excessive administration. Its implementation should therefore be carefully coordinated to avoid stifling valuable, potentially life‐saving research. It may particularly affect trials with orphan medicinal products, in rare genetic diseases or in oncology. These can be more difficult to manage due to complex or poorly understood disease pathology and the need to involve multiple trial sites with experts in different countries. This article illustrates the complexity of such trials, contains a brief analysis of the Directive, highlights the importance of a ‘flexible’ approach to trial design and conduct and includes a list of recommendations that could accompany the implementation of the Directive. Copyright © 2004 John Wiley & Sons, Ltd.