bluuebunny/crossref_metadata_2025_split huggingface dataset:
Living Free Radical Polymerization of Cyclodextrin Host‐Guest Complexes of Styrene via the Reversible Addition Fragmentation Chain Transfer (RAFT) Process in Aqueous Solution
Authors: Köllisch Heike , Barner‐Kowollik Christopher , Ritter Helmut 
Published: May 2006

AbstractSummary: Host‐guest complexes of styrene and randomly methylated β‐cyclodextrin (m‐β‐CD) were polymerized in aqueous medium via the reversible addition fragmentation chain transfer (RAFT) process. 3‐Benzylsulfanylthiocarbonylsulfanylpropionic acid (TTC) was used as trithiocarbonate‐type RAFT agent. The results indicate a controlled character of the polymerization of the styrene complexes as the number‐average molecular weight, $\overline M _{\rm n}$, increases linearly with monomer to polymer conversion; however, the molecular weights of the obtained polystyrenes deviate to higher values than those theoretically predicted. Nevertheless, the molecular weights can be controlled by variation of the initial RAFT agent concentration. The polystyrenes produced in this system exhibited narrower polydispersities (1.23 < $\overline M _{\rm w} /\overline M _{\rm n}$ < 2.36) than those produced without RAFT agent (5.24 < $\overline M _{\rm w} /\overline M _{\rm n}$ < 9.21) under similar conditions. The present contribution represents the first example of RAFT polymerization of a m‐β‐CD‐complexed hydrophobic vinylmonomer (styrene) from homogenous aqueous solution.Schematic presentation of complexation and RAFT polymerization of m‐β‐CD‐complexed styrene with TTC as RAFT agent and evolution of the full molecular weight distributions in the CD‐mediated styrene free radical RAFT polymerization.imageSchematic presentation of complexation and RAFT polymerization of m‐β‐CD‐complexed styrene with TTC as RAFT agent and evolution of the full molecular weight distributions in the CD‐mediated styrene free radical RAFT polymerization.
Supramolecular Self‐Assembly of Polymer‐Functionalized Carbon Nanotubes on Surfaces
Authors: Gao Chao 
Published: May 2006

AbstractSummary: Supramolecular self‐assembly of poly(methyl methacrylate)‐grafted multiwalled carbon nanotubes (MWNT‐g‐PMMA) was reported herein. The MWNT‐g‐PMMA (85 wt.‐% PMMA) dispersed in tetrahydrofuran could self‐assemble into suprastructures on surfaces such as gold, mica, silicon, quartz, or carbon films. With decreasing concentration of the MWNT‐g‐PMMA from 3 to 0.1 mg · mL−1, the assembled structures changed from cellular and basketwork‐like forms to multilayer cellular networks and individual needles. SEM, AFM, and TEM measurements confirmed the morphology of the assembled suprastructures, and revealed the assembly mechanism. Phase separation during evaporation of the solvent drives the MWNT‐g‐PMMA nanohybrids to assemble and form the suprastructures, and the rigid MWNTs stabilize the structures.SEM images of self‐assembled suprastructures of basketwork (a), cellular network (b), and needles (c) from the THF solution of the PMMA‐grafted MWNTs on gold surface.imageSEM images of self‐assembled suprastructures of basketwork (a), cellular network (b), and needles (c) from the THF solution of the PMMA‐grafted MWNTs on gold surface.
Effect of Chain Straightening on Plateau Modulus and Entanglement Molecular Weight of Ni‐diimine Poly(1‐hexene)s
Authors: Ye Zhibin , Feng Wei , Zhu Shiping , Yu Qiang 
Published: May 2006

AbstractSummary: In this communication, we report the first rheological study on the chain‐straightened Ni‐diimine poly(1‐hexene)s and investigate the unique effect of chain straightening on plateau modulus and entanglement molecular weight of this series of polymers. Two Ni‐diimine poly(1‐hexene) samples having different levels of chain straightening were prepared with a chain‐walking Ni‐diimine catalyst, (ArNC(An)C(An)NAr)NiBr2 (An = acenaphthene, Ar = 2,6‐(i‐Pr)2C6H3) at two different temperatures. Rheological analyses show that the chain‐straightened polymers exhibit significantly enhanced plateau modulus and reduced entanglement molecular weight compared to regular poly(1‐hexene)s by metallocene catalysis. Such an effect becomes more pronounced with an increase in the level of chain straightening.Loss moduli G″(ω) versus reduced angular frequency in a linear, natural logarithm plot for the three polymers at the reference temperature of 100 °C.imageLoss moduli G″(ω) versus reduced angular frequency in a linear, natural logarithm plot for the three polymers at the reference temperature of 100 °C.
A Main‐Chain Liquid‐Crystalline Oligomer Prepared by in situ Photopolymerization of an LC Monomer Having Cinnamate Moieties
Authors: Kihara Hideyuki , Tamaoki Nobuyuki 
Published: May 2006

AbstractSummary: A liquid‐crystalline (LC) compound, having a cinnamate moiety on each end of the molecule, was synthesized and irradiated with UV light in its LC phase in the presence of a triplet sensitizer. Various measurements of the irradiated sample revealed that the linearly structured LC oligomers were formed by [2+2] cycloaddition of the cinnamate moieties, and that the resultant cyclobutane units dominantly assumed an anti head‐to‐head configuration.Schematic structures of the LC oligomer obtained by photopolymerization.imageSchematic structures of the LC oligomer obtained by photopolymerization.
Substitution and protonation effects on spin–spin coupling constants in prototypical aromatic rings: C6H6, C5H5N and C5H5P
Authors: Del Bene Janet E. , Elguero José 
Published: May 2006

AbstractAb initio equation‐of‐motion coupled cluster calculations have been carried out to evaluate one‐, two‐, and three‐bond 13C13C, 15N13C, 31P13C coupling constants in benzene, pyridine, pyridinium, phosphinine, and phosphininium. The introduction of N or P heteroatoms into the aromatic ring not only changes the magnitudes of the corresponding XC coupling constants (J, for X = C, N, or P) but also the signs and magnitudes of corresponding reduced coupling constants (K). Protonation of the heteroatoms also produces dramatic changes in coupling constants and, by removing the lone pair of electrons from the σ‐electron framework, leads to the same signs for corresponding reduced coupling constants for benzene, pyridinium, and phosphininium. CC coupling constants are rather insensitive to the presence of the heteroatoms and protonation. All terms that contribute to the total coupling constant (except for the diamagnetic spin‐orbit (DSO) term) must be computed if good agreement with experimental data is to be obtained. Copyright © 2006 John Wiley & Sons, Ltd.
Effects of cold storage on the function and morphology of isolated urinary bladder in rat
Authors: Liu Guiming , Daneshgari Firouz 
Published: May 2006

AbstractAimsWe investigated the effects of 24‐ and 48‐hr storage at 4°C in Krebs solution on the function and morphology of isolated, rat urinary bladders.MethodsStrips of bladder were obtained from eight male Sprague–Dawley rats. Six strips were harvested from each bladder and randomized to storage for 24 or 48 hr at 4°C in Krebs solution or examination immediately after harvest. Contractile responses of the strips to potassium chloride (KCl), electric field stimulation (EFS), adenosine 5′‐triphosphate (ATP) and carbamylcholine (CCh) were assessed. Histological examination of the bladder strips was performed. The pO2, pCO2, and pH of the solution in each storage container were measured at each storage time point.ResultsCold storage induced a significant decrease in the amplitude of contraction in response to KCl and EFS after 24 or 48 hr of storage compared with control. The response of the bladder strips to ATP and CCh was significantly reduced after 48‐hr storage compared with control, but not 24‐hr storage. The pO2 and pCO2 decreased after cold storage. The pH increased after 24 hr of storage and remained stable between 24 and 48 hr of storage. Histological evaluation of the strips showed tissue swelling after 24 and 48 hr of storage.ConclusionsThese results suggest that the morphology and function of bladder strips stored for 24 to 48 hr at 4°C in Krebs solution undergo significant changes. Further studies are needed to assess the allowable time for storage of bladder tissue. Neurourol. Urodynam. © 2006 Wiley‐Liss, Inc.
Reliability inference for field conditions from accelerated degradation testing
Authors: Liao Haitao , Elsayed Elsayed A. 
Published: May 2006

AbstractAccelerated degradation testing (ADT) is usually conducted under deterministic stresses such as constant‐stress, step‐stress, and cyclic‐stress. Based on ADT data, an ADT model is developed to predict reliability under normal (field) operating conditions. In engineering applications, the “standard” approach for reliability prediction assumes that the normal operating conditions are deterministic or simply uses the mean values of the stresses while ignoring their variability. Such an approach may lead to significant prediction errors. In this paper, we extend an ADT model obtained from constant‐stress ADT experiments to predict field reliability by considering the stress variations. A case study is provided to demonstrate the proposed statistical inference procedure. The accuracy of the procedure is verified by simulation using various distributions of field stresses. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006.
The antibody 2B4 directed against the Epstein–Barr virus (EBV)‐encoded nuclear antigen 1 (EBNA1) detects MAGE‐4: implications for studies on the EBV association of human cancers
Authors: Hennard C , Pfuhl T , Buettner M , Becker K‐F , Knöfel T , Middeldorp J , Kremmer E , Niedobitek G , Grässer FA 
Published: May 2006

AbstractWe have previously developed two monoclonal antibodies against the Epstein–Barr Virus (EBV) nuclear antigen 1 (EBNA1), designated 1H4 and 2B4. Both detect EBNA1 by in situ staining in established EBV‐positive tumours, e.g. Hodgkin's lymphoma and nasopharyngeal carcinoma. An association of EBV with other tumours, notably breast carcinomas, has been reported but remains controversial. Using the antibody 2B4, a nuclear protein has been detected in breast carcinomas that were EBV‐negative by other methods, suggesting cross‐reactivity with a cellular protein. Furthermore, an association of EBV with various other carcinomas has been reported on the basis of 2B4 immunohistochemistry. Here we show that 2B4 also binds to MAGE‐4, a cancer testis antigen expressed in a variety of tumour cells, including breast carcinoma, seminoma and EBV‐negative cases of Hodgkin's lymphoma. We conclude that the 2B4 antibody is not suitable for the detection of EBV infection but that additional techniques, particularly in situ hybridization for the detection of the EBV‐encoded RNAs (EBERs), should be employed to confirm the presence of EBV. Our results add to the evidence indicating that breast cancer is not an EBV‐associated disease. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
MMTV‐like sequences in human breast cancer: a fluorescent PCR/laser microdissection approach
Authors: Zammarchi F , Pistello M , Piersigilli A , Murr R , Cristofano C Di , Naccarato AG , Bevilacqua G 
Published: May 2006

AbstractThe hypothesis that a retrovirus homologous to the mouse mammary tumour virus (MMTV) is involved in human breast cancer aetiology has fascinated scientists from many years, but it has never been convincingly demonstrated. Renewed interest in this hypothesis developed when an MMTV env gene‐like sequence was found in 38% of human breast cancer tissues. Whereas some subsequent studies confirmed these findings, others did not. The main reasons for this discrepancy, among others, are the different sensitivities and technical details of current molecular approaches to the detection of these sequences. This study is an attempt to find sensitive and reproducible conditions capable of detecting MMTV env‐like sequence in human samples. To this end, we first developed a fluorescence nested‐PCR (FN‐PCR) method that was able to detect very low copies of the viral genome, and then screened a panel of 45 frozen breast cancer samples obtained by laser microdissection. The MMTV env gene‐like sequence was found in 15 (33%) of the human breast cancers analysed, whereas the same sequence was detectable neither in normal tissues nor in other types of tumour. Sequence analysis revealed 96% homology with the MMTV genome, but no other significant similarities with the human genome. The combined use of frozen material, microdissected cell populations and FN‐PCR provides a novel, sensitive, robust, non‐radioactive and fast methodology for the molecular detection of human‐MTV. This approach might be successfully used in large molecular studies that aim to investigate the hypothesis of a retroviral aetiology of human breast cancer. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Prednisolone promotes remission and gastric mucosal regeneration in experimental autoimmune gastritis
Authors: Biondo M , Field J , Toh B‐H , Alderuccio F 
Published: May 2006

AbstractA cardinal feature of organ‐specific autoimmunity is destructive pathology in the target organ. In human and experimental models of autoimmune gastritis, mononuclear cell infiltration and cellular destruction in the gastric mucosa are disease hallmarks. Strategies to cure autoimmune disease must not only establish immunological tolerance to autoantigen, but also rid the organ of pathogenic autoreactive cells. The present study has assessed the effect of prednisolone treatment in clearing the inflammatory infiltrate in experimental autoimmune gastritis and in preventing disease relapse in athymic compared with euthymic mice. Experimental autoimmune gastritis was induced by neonatal thymectomy or by transgenic expression of GM‐CSF (PC‐GMCSF mice). Groups of mice were treated with prednisolone (10 mg/kg per day) for 10 weeks or with prednisolone for 10 weeks followed by 10 weeks without prednisolone. Stomachs were examined for gross morphological changes, and by histology and immunohistochemistry for composition of inflammatory infiltrate and gastric mucosal integrity. Autoantibody to gastric H+/K+ ATPase was determined by ELISA. Prednisolone promoted remission of gastritis in both mouse models of experimental autoimmune gastritis, evident by reduction in stomach size, clearing of gastric inflammatory infiltrate, and regeneration of the gastric mucosa. Prednisolone withdrawal resulted in disease relapse in all PC‐GMCSF mice, whereas approximately 40% of neonatal thymectomy mice retained normal stomach morphology and remained free of gastric pathology. It is concluded that prednisolone promotes remission and gastric mucosal regeneration in experimental autoimmune gastritis. Prolonged remission of autoimmune gastritis in some athymic mice suggests a role for the thymus in disease relapse. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Development of a protocol for the semi‐synthesis and purification of betaxanthins
Authors: Gandía‐Herrero Fernando , García‐Carmona Francisco , Escribano Josefa 
Published: May 2006

AbstractA method for the analytical and semi‐preparative chromatographic purification of betaxanthins is described together with an improved procedure for the semi‐synthesis of these compounds from betalamic acid. Standard conditions for obtaining preparative amounts of betaxanthins free of the precursor amino acids are provided. Following this procedure, 14 pure betaxanthins were obtained with yields of up to 100%. A simple reversed‐phase HPLC protocol for pigment identification and quantification is also provided. Calibration for betaxanthins is reported for the first time using the synthesised and purified pigments as standards. Structures were confirmed by UV–vis spectroscopy, HPLC retention times and electrospray ionization mass spectrometry. Betaxanthins can be obtained pure, and in sufficient amounts for further studies, which opens up new perspectives in the research and applications of these pigments. Copyright © 2006 John Wiley & Sons, Ltd.
Determination of catalase‐like activity in plants based on the amperometric monitoring of hydrogen peroxide consumption using a carbon paste electrode modied with ruthenium(IV) oxide
Authors: Dousikou Melpomeni F. , Koupparis Michael A. , Efstathiou Constantinos E. 
Published: May 2006

AbstractA carbon paste electrode containing ruthenium(IV) oxide as a modier was tested as an effective hydrogen peroxide amperometric sensor in bulk measurements (hydrodynamic amperometry). Factors that influence its overall analytical performance, such as pH and the applied potential, were examined. The RuO2‐modied electrode displayed high sensitivity towards hydrogen peroxide, with detection limits as low as 0.02 mm at pH 7.4 and 0.007 mm at pH 9.0. The method was applied for monitoring the decomposition of hydrogen peroxide (by catalase) in phosphate buffer of pH 7.4. The relative response of the electrode towards ascorbic acid was assessed and it was found that the selectivity of the RuO2‐modied electrode towards hydrogen peroxide over ascorbic acid could be signicantly improved by electro‐polymerizing m‐phenylenediamine on its surface prior to measurements. The RuO2‐modied electrode was used for the kinetic (xed time) determination of catalase activity in the range of 4–40 U/mL (detection limit 1.2 U/mL). The method was applied to the determination of catalase‐like activity in various plant materials (recovery ranged from 93 to 101%, detection limit 480 U/100 g). Copyright © 2006 John Wiley & Sons, Ltd.
RP‐HPLC detection of a sulphiting‐induced artefact from paeoniflorin in dried roots of Paeonia lactiflora
Authors: Hayes Patricia Y. , Lehmann Reg , Penman Kerry , Bone Kerry M. , Kitching William , De Voss James J. 
Published: May 2006

AbstractPaeoniflorin is one of the bioactive ingredients of the roots of Paeonia lactiflora (Paeoniaceae). A comparative study of processed and non‐processed commercial samples of dried roots of P. lactiflora indicated a very low level of paeoniflorin in the processed sample and the formation of a new more polar component, sodium paeoniflorin sulphonate, during treatment of the roots with sulphiting agents. Copyright © 2006 John Wiley & Sons, Ltd.
A supramolecular network of 2‐(4,4,5,5‐tetramethyl‐3‐oxylimidazoline‐1‐oxide)‐5‐bromopyridine built through π–π stacking and hydrogen bonding interactions
Authors: Rajadurai Chandrasekar , Fuhr Olaf , Enkelmann Volker , Baumgarten Martin 
Published: May 2006

AbstractThe X‐ray study of 2‐(4,4,5,5‐tetramethyl‐3‐oxylimidazoline‐1‐oxide)‐5‐bromopyridine (PyNN) shows an unusual 3‐D supramolecular assembly formed by the combined non‐covalent interactions of π–π stacking and H‐bonding forces. The mean π–π stacking distance between two pyridine units is ∼3.64 Å. The angle between the plane of the pyridine ring and the stack column axis (c‐axis) is 7.46°. The H‐bonding distance between the oxygen atom of the water and the nitronyl nitroxide (NN) oxygen [H···ON] is 1.891 Å. Two potential short NO···ON contacts are found (NO1···O1N = 3.673 Å and NO1···O2N = 3.695 Å) along the stacked column. Four water molecules through H‐bonding with four different radical oxygens form a perfect square in the a, b plane which extends as a tubular cage along the stack axis. Experimental spin densities of PyNN estimated from the 1H‐NMR spectroscopy and its bulk magnetic property have been correlated with the X‐ray structure in an attempt to understand the possible magnetic exchange interactions. The observed low temperature antiferromagnetic interaction is analyzed on the basis of McConnell's model I (spin polarization approach) and this magnetic behavior is probably due to the dominant NO···ON close contacts along the chain surpassing the stacking, H‐bonding and other interactions. Copyright © 2006 John Wiley & Sons, Ltd.
A new method for the determination of cooperative hydrogen bonding enthalpy of proton acceptors with associated species of alcohols
Authors: Solomonov Boris N. , Varfolomeev Mikhail A. , Novikov Vladimir B. 
Published: May 2006

AbstractA calorimetric method for the determination of cooperative hydrogen bonding (HB) enthalpy of protonacceptors (B) with associated species of alcohols is proposed. The average enthalpy of cooperative HB ofpyridine with associated species of alcohols was found to be −19.8 ± 0.6 kJ mol−1 for all alcohols investigated. Thisvalue exceeds the enthalpy of HB in the complex ROH … NC5H5 (the average for all alcohols is −15.8 ± 0.2 kJ mol−1) by 20–30%. Cooperativity factors (Ab, AOx) of hydrogen bonds for (ROH)2 … NC5H5 complexes were determined using the IR‐spectroscopic method. The average values for the alcohols under consideration were found to be Ab = 1.41 ± 0.04 and AOx = 1.54 ± 0.05. On the basis of IR‐spectroscopic and calorimetric data, the enthalpy of cooperative interactions of pyridine with the dimer (ROH)2 was estimated. This value for all the alcohols studied is, on average, −20.9 ± 0.1 kJ mol−1. Copyright © 2006 John Wiley & Sons, Ltd.
Long‐range polar and steric effects in propionate‐SG1‐type alkoxyamines (SG1‐CHMeCOOX): a multiparameter analysis
Authors: Ananchenko Gennady , Beaudoin Emmanuel , Bertin Denis , Gigmes Didier , Lagarde Pierre , Marque Sylvain R. A. , Revalor Eve , Tordo Paul 
Published: May 2006

AbstractThe effects of the substituent X on the homolysis rate constants (kd) of SG1‐propionate type alkoxyamines (SG1‐CHMeCOOX) are analyzed by a multiparametric equation with υ, the steric constant and σI, the polar inductive/field Hammett constant of X. An influence of long‐range polar and steric effects on kd was observed, that is, decrease in kd with increasing size of the X group and increase in kd with increasing polarity of the X group. Copyright © 2006 John Wiley & Sons, Ltd.
Electrostatic model of bond dissociation energies in polyhalogen methanes
Authors: Jaworski Jan S. , Cembor Marek , Koliński Michał 
Published: May 2006

AbstractHomolytic bond dissociation energy (BDE) for CH and CX (X = F, Cl, or Br) bonds in polyhalogen methanes was successfully correlated with a two‐parameter model describing the repulsion energy of the bonding electron pair with other electrons and its attraction with nuclei, respectively. BDE values for seven molecules were predicted and compared with those calculated by a DFT method. Copyright © 2006 John Wiley & Sons, Ltd.
Catalytic chain‐transfer synthesis of 1,1,2,2‐tetrahydroperfluoroalkyl methacrylate macromonomers
Authors: Romack Timothy J. , Kaur Gurpreet , Weaver Seth F. , Harrelson Sarah K. , Kenward Angela G. 
Published: May 2006

AbstractThe successful catalytic chain‐transfer synthesis of 1,1,2,2‐tetrahydroperfluoroalkyl methacrylate macromonomers with [bis(aqua)bis(difluoroboryl)dimethylglyoximato]cobalt(II) as a catalyst is reported. Fluoroalkyl methacrylate macromonomers were synthesized in acetone with 2,2′‐azobisisobutyronitrile as the initiator. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4136–4141, 2006