bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemoenzymatic Synthesis of Branched Polymers
Authors: Peeters Joris W. , Palmans Anja R. A. , Meijer E. W. , Koning Cor E. , Heise Andreas 
Published: April 2005

AbstractSummary: The combination of enzymatic polymerization with ATRP for the synthesis of branched (block) copolymers was investigated. Heterotelechelic polycaprolactone macroinimer was synthesized in a one‐pot enzymatic procedure by using 2‐hydroxyethyl α‐bromoisobutyrate as a bifunctional initiator. A polymerizable end group was introduced by subsequent in situ enzymatic acrylation with vinyl acrylate. Branched polymers were obtained by subsequent atom transfer radical polymerization (ATRP).Enzymatic synthesis of heterotelechelic macromonomers and subsequent self condensing vinyl polymerization by ATRP.imageEnzymatic synthesis of heterotelechelic macromonomers and subsequent self condensing vinyl polymerization by ATRP.
The Mechanical Deformation Process of Electrospun Polymer Nanocomposite Fibers
Authors: Kim Gyeong‐Man , Lach Ralf , Michler Goerg Hannes , Chang Young‐Wook 
Published: April 2005

AbstractSummary: The mechanical deformation processes of poly(methyl methacrylate)/ montmorillonite nanocomposites and their electrospun fibers were investigated by in situ tensile tests under a transmission electron microscope depending on their morphology. While the polymer nanocomposites deformed in a brittle manner, i.e., crazing, the electrospun polymer nanocomposite fibers deformed through a shear flow process leading to “nanonecking” due to the strong overlap of stress fields caused by nanopores within the fiber under a uniaxial tensile load. This unique change in deformation behavior provides the possibility that the intrinsic brittle material could be manipulated to be ductile without sacrificing its other attractive properties through a well‐controlled electrospinning process.TEM micrograph of a low temperature fractured fiber showing the nanoporous surface structure.imageTEM micrograph of a low temperature fractured fiber showing the nanoporous surface structure.
Hollow Cu‐NP Spheres Made from Electroless Cu Deposition with Colloidal Particles as Templates
Authors: Cong Hailin , Zhang Maofeng , Cao Weixiao 
Published: April 2005

AbstractSummary: Hollow copper nanoparticle (Cu‐NP) spheres with different wall thicknesses were prepared with organic and inorganic colloids as core combining self‐assembly and electroless Cu deposition techniques. The hollow Cu‐NP spheres made from polymeric colloids possessed a thicker wall but were easy to break in the removal of the core by THF, while those from SiO2 colloids had thinner wall and remained intact in the removal of the core by HF.TEM image of the hollow Cu‐NP spheres.imageTEM image of the hollow Cu‐NP spheres.
Effect of the Brush Structure on the Degradation Mechanism of Polystyrene–Clay Nanocomposites
Authors: Chen Kai , Susner Michael A. , Vyazovkin Sergey 
Published: April 2005

AbstractSummary: Pyrolysis‐GC‐MS and TGA‐FT‐IR methods have been used to perform a comparative degradation study of polystyrene and a polystyrene–clay composite. An abnormally high yield of α‐methylstyrene has been detected for the composite. This and other differences in degradation products have been explained by enhanced intermolecular interaction of the grafted PS chains, forming a brush structure. A conceptual model of the process has been suggested.GC pyrograms of virgin PS (A) and PS–clay composite (B) pyrolyzed at 500 °C (1: styrene; 2: 2,4‐diphenylbut‐1‐ene; 2′: dimer derivatives; 3: 2,4,6‐triphenylhex‐1‐ene; 3′: trimer derivatives; 4: α‐methylstyrene).imageGC pyrograms of virgin PS (A) and PS–clay composite (B) pyrolyzed at 500 °C (1: styrene; 2: 2,4‐diphenylbut‐1‐ene; 2′: dimer derivatives; 3: 2,4,6‐triphenylhex‐1‐ene; 3′: trimer derivatives; 4: α‐methylstyrene).
Monodisperse polystyrene microspheres prepared by dispersion polymerization with microwave irradiation
Authors: Xu Zu‐Shun , Deng Zi‐Wei , Hu Xiao‐Xi , Li Lei , Yi Chang‐Feng 
Published: April 2005

AbstractMonodisperse polystyrene microspheres with diameters of 200–500 nm were prepared by dispersion polymerization with microwave irradiation with poly(N‐vinylpyrrolidone) as a steric stabilizer and 2,2′‐azobisisobutyronitrile as a radical initiator in an ethanol/water medium. The morphology, size, and size distribution of the polystyrene microspheres were characterized with transmission electron microscopy and photon correlation spectroscopy, and the formed films of the polystyrene dispersions were characterized with atomic force microscopy. The effects of the monomer concentration, stabilizer concentration, and initiator concentration on the size and size distribution of the polystyrene microspheres were investigated. The polystyrene microspheres prepared by dispersion polymerization with microwave irradiation were smaller, more uniform, and steadier than those obtained with conventional heating. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2368‐2376, 2005
Geometric cooperativity and anticooperativity of three‐body interactions in native proteins
Authors: Li Xiang , Liang Jie 
Published: April 2005

AbstractCharacterizing multibody interactions of hydrophobic, polar, and ionizable residues in protein is important for understanding the stability of protein structures. We introduce a geometric model for quantifying 3‐body interactions in native proteins. With this model, empirical propensity values for many types of 3‐body interactions can be reliably estimated from a database of native protein structures, despite the overwhelming presence of pairwise contacts. In addition, we define a nonadditive coefficient that characterizes cooperativity and anticooperativity of residue interactions in native proteins by measuring the deviation of 3‐body interactions from 3 independent pairwise interactions. It compares the 3‐body propensity value from what would be expected if only pairwise interactions were considered, and highlights the distinction of propensity and cooperativity of 3‐body interaction. Based on the geometric model, and what can be inferred from statistical analysis of such a model, we find that hydrophobic interactions and hydrogen‐bonding interactions make nonadditive contributions to protein stability, but the nonadditive nature depends on whether such interactions are located in the protein interior or on the protein surface. When located in the interior, many hydrophobic interactions such as those involving alkyl residues are anticooperative. Salt‐bridge and regular hydrogen‐bonding interactions, such as those involving ionizable residues and polar residues, are cooperative. When located on the protein surface, these salt‐bridge and regular hydrogen‐bonding interactions are anticooperative, and hydrophobic interactions involving alkyl residues become cooperative. We show with examples that incorporating 3‐body interactions improves discrimination of protein native structures against decoy conformations. In addition, analysis of cooperative 3‐body interaction may reveal spatial motifs that can suggest specific protein functions. Proteins 2005. © 2005 Wiley‐Liss, Inc.
Rapid assessment of contact‐dependent secondary structure propensity: Relevance to amyloidogenic sequences
Authors: Yoon Sukjoon , Welsh William J. 
Published: April 2005

AbstractWe have previously demonstrated that calculation of contact‐dependent secondary structure propensity (CSSP) is highly sensitive in detecting non‐native β‐strand propensities in the core sequences of known amyloidogenic proteins. Here we describe a CSSP method based on an artificial neural network that rapidly and accurately quantifies the influence of tertiary contacts (TCs) on secondary structure propensity in local regions of protein sequences. The present method exhibited 72% accuracy in predicting the alternate secondary structure adopted by chameleon sequences located in highly disparate TC regions. Analysis of 1930 nonhomologous protein domains reveals that the α‐helix and the β‐strand largely share the same sequence context, and that tertiary context is a major determinant of the native conformation. Conversely, it appears that the propensity of random coils for either the α‐helix or the β‐strand is largely invariant to tertiary effects. The present CSSP method successfully reproduced the amyloidogenic character observed in local regions of the human islet amyloid polypeptide (hIAPP). Furthermore, CSSP profiles were strongly correlated (r = 0.76) with the observed mutational effects on the aggregation rate of acylphosphatase. Taken together, these results provide compelling evidence in support of the present CSSP approach as a sensitive probe useful for analysis of full‐length proteins and for detection of core sequences that may trigger amyloid fibril formation. The combined speed and simplicity of the CSSP method lends itself to proteome‐wide analysis of the amyloidogenic nature of common proteins. Proteins 2005. © 2005 Wiley‐Liss, Inc.
Form and function of the corpus luteum during the human menstrual cycle
Authors: Baerwald A. R. , Adams G. P. , Pierson R. A. 
Published: April 2005

AbstractObjectiveTo characterize the growth and regression of the corpus luteum (CL) during an interovulatory interval (IOI) using serial transvaginal ultrasonography.MethodsFifty healthy women of reproductive age with a history of regular menstrual cycles underwent daily transvaginal ultrasonography for one IOI. Measurements of luteal area and luteal numerical pixel value (NPV) were recorded each day after ovulation until the CL could no longer be detected. Blood was drawn every third day during the IOI to measure serum concentrations of progesterone and estradiol‐17β.ResultsCorpora lutea were of two morphological types: those with a central fluid‐filled cavity (CFFC) (78%) and those without (22%). Eighty‐eight percent of women exhibited a CL containing a CFFC 2 days after ovulation, followed by 34% 13 days after ovulation and 2% 27 days after ovulation. Luteal area, progesterone concentration and estradiol concentration increased for approximately the first 6 days following ovulation followed by a subsequent decline. Luteal NPV decreased from days 1 to 11 and increased during days 11–16. Changes in luteal area, NPV, progesterone and estradiol concentrations did not differ in women with two versus three waves of follicular development.ConclusionsPeak luteal function, as determined by maximum luteal area, progesterone concentration and estradiol concentration, is observed 6 days following ovulation. Luteal NPV is reflective of morphological and endocrinological changes in the CL. The development of a CFFC during luteinization is a normal physiological phenomenon. The CL can be detected, but is not functional, during the follicular phase of the menstrual cycle. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Effects of ultrasound on maternal‐fetal bonding: a comparison of two‐ and three‐dimensional imaging
Authors: Ji E.‐K. , Pretorius D. H. , Newton R. , Uyan K. , Hull A. D. , Hollenbach K. , Nelson T. R. 
Published: April 2005

AbstractObjectivesThe purpose of this study was to evaluate the effect of two‐dimensional (2DUS) compared to three‐dimensional ultrasound (3DUS) imaging on the maternal‐fetal bonding process.MethodsFifty mothers who had 2DUS and 50 who had 2DUS and 3DUS were included in the study. A postpartum survey by telephone interview was carried out to assess maternal‐fetal bonding. Bonding was evaluated by analysis of extent of prenatal image sharing, maternal ability to form a mental picture of the baby and mother's comments about their ultrasound images. Data were analyzed using the independent t‐test, Chi‐square and Mann–Whitney U‐tests.ResultsMothers who received 3DUS showed their ultrasound images to more people (median, 27.5; interquartile range, 14.5–40.0) than mothers receiving 2DUS alone (median, 11.0; interquartile range, 5.0–25.5) (P < 0.001, Z = −3.539). Eighty‐two percent of the subjects screened with 3DUS had a greater tendency to form a mental picture of the baby postexamination compared to 39% of the 2DUS subjects (P < 0.001, Z = −3.614). Mothers receiving a 3DUS study were more likely to receive comments on the similarities/differences of the neonate compared to those having 2DUS studies. Furthermore, 70% of the mothers receiving 3DUS felt they ‘knew’ the baby immediately after birth vs. 56% of the mothers receiving 2DUS (P = 0.009, Z = −2.613). Both 2DUS and 3DUS experiences were positive, however, the comments made by the mothers undergoing 3DUS (n = 18) were more exclamatory (amazed, wonderful, fabulous) than those undergoing 2DUS (n = 4). Patients having a 3DUS examination consistently scored higher than those having a 2DUS examination alone for all categories of maternal‐fetal bonding.Conclusion3DUS appears to more positively influence the perceptions of mothers to their babies postbirth compared to 2DUS. Specifically, mothers who had 3DUS showed their ultrasound images to a greater number of people compared to mothers who had 2DUS alone and this may represent mother's social support system. 3DUS may have a greater impact on the maternal‐fetal bonding process. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Isolation and sequence analysis of the gene URA3 encoding the orotidine‐5′‐phosphate decarboxylase from Candida glycerinogenes WL2002‐5, an industrial glycerol producer
Authors: Li Yanli , Shen Wei , Wang Zhengxiang , Liu Ji‐Quan , Rao Zhiming , Tang Xueming , Fang Huiying , Zhuge Jian 
Published: April 2005

AbstractThe URA3 gene of Candida glycerinogenes WL2002‐5, an industrial glycerol producer encoding orotidine‐5′‐phosphate decarboxylase enzyme, was isolated by complementation cloning in Saccharomyces cerevisiae. DNA sequence analysis revealed the presence of an open reading frame (ORF) of 786 bp, encoding a 262 amino acid protein, which shares 71.65% amino acid sequence similarity to the S. cerevisiae URA3 protein. Furthermore, the cloned ORF fully complemented the ura3 mutation of S. cerevisiae, confirming that it encodes for the C. glycerinogenes Ura3 (CgUra3) protein. The GenBank Accession No. for CgUra3 is AY623794. Copyright © 2005 John Wiley & Sons, Ltd.
Evaluation of the Saccharomyces cerevisiae ADH2 promoter for protein synthesis
Authors: Michael Lee K. , DaSilva Nancy A. 
Published: April 2005

AbstractThe Saccharomyces cerevisiae ADH2 promoter (PADH2) is repressed several hundred‐fold in the presence of glucose; transcription is initiated once the glucose in the medium is exhausted. The promoter can thus be utilized for effective regulation of recombinant gene expression in S. cerevisiae without the addition of an inducer. To evaluate this promoter in the absence of plasmid copy number and stability variations, the PADH2 − lacZ cassette was integrated into the yeast chromosomes. The effects of medium composition, glucose concentration and cultivation time on promoter derepression and expression level were investigated. Maximum protein activity was obtained after 48 h of growth in complex YPD medium containing 1% glucose. The widely used S. cerevisiae GAL1 and CUP1 promoters both require the addition of an inducer [galactose and copper(II) ion, respectively] before regulated genes will be expressed. The strengths of these three different promoters were compared for cells containing one copy of an integrated lacZ gene under their control. The ADH2 promoter was superior for all induction strategies investigated. Copyright © 2005 John Wiley & Sons, Ltd.
Molecular cloning and biochemical characterization of a 3′(2′),5′‐bisphosphate nucleotidase from Debaryomyces hansenii
Authors: Aggarwal Monika , Bansal Parmil K. , Mondal Alok K. 
Published: April 2005

AbstractThe enzyme 3′(2′),5′‐bisphosphate nucleotidase catalyses a reaction that converts 3′‐phosphoadenosine‐5′‐phosphate (PAP) to adenosine‐5′‐phosphate (AMP) and inorganic phosphate (Pi). The enzyme from Saccharomyces cerevisiae is highly sensitive to sodium and lithium and is thus considered to be the in vivo target of salt toxicity in yeast. In S. cerevisiae, the HAL2 gene encodes this enzyme. We have cloned a homologous gene, DHAL2, from the halotolerant yeast Debaryomyces hansenii. DNA sequencing of this clone revealed a 1260 bp open reading frame (ORF) that putatively encoded a protein of 420 amino acid residues. S. cerevisiae transformed with DHAL2 gene displayed higher halotolerance. Biochemical studies showed that recombinant Dhal2p could efficiently utilize PAP (Km17 µM) and PAPS (Km48 µM) as substrate. Moreover, we present evidence that, in comparison to other homologues from yeast, Dhal2p displays significantly higher resistance towards lithium and sodium ions. The nucleotide sequence of DHAL2 gene has been submitted to Genbank (Accession No. AY340817). Copyright © 2005 John Wiley & Sons, Ltd.
TOR kinase pathway and 14‐3‐3 proteins regulate glucose‐induced expression of HXT1, a yeast low‐affinity glucose transporter
Authors: Tomás‐Cobos Lidia , Viana Rosa , Sanz Pascual 
Published: April 2005

AbstractExpression of HXT1, a gene encoding a Saccharomyces cerevisiae low‐affinity glucose transporter, is regulated by glucose availability, being activated in the presence of glucose and inhibited when the levels of the sugar are scarce. In this study we show that 14‐3‐3 proteins are involved in the regulation of the expression of HXT1 by glucose. We also demonstrate that 14‐3‐3 proteins, in complex with Reg1, a regulatory subunit of Glc7 protein phosphatase, interact physically with Grr1 (a component of the SCF–Grr1 ubiquitination complex), a key player in the process of HXT1 induction by glucose. In addition, we show that the TOR kinase pathway participates actively in the induction of HXT1 expression by glucose. Inhibition of the TOR kinase pathway by rapamycin treatment abolishes HXT1 glucose induction. A possible involvement of PP2A protein phosphatase complex, through the Cdc55 B‐subunit, in the glucose induction of HXT1 is also discussed. Copyright © 2005 John Wiley & Sons, Ltd.
Cloning and heterologous expression of the NADPH cytochrome P450 oxidoreductase genes from an industrial dicarboxylic acid‐producing Candida tropicalis
Authors: He Feng , Chen Yuan Tong 
Published: April 2005

AbstractNADPH cytochrome P450 oxidoreductase (CPR) catalyses the transfer of electrons during P450‐mediated oxidation, which plays an important role in the ω‐oxidation pathway of Candida tropicalis. Two putative allelic genes, CPR‐a and CPR‐b, were cloned from the long chain dicarboxylic acid‐producing Candida tropicalis 1230, using cassette PCR methods. Both the identified open reading frames predict the gene products of 679 amino acid residues. The deduced amino acid sequences of CPR‐a and CPR‐b are highly homologous to CPR genes from C. tropicalis ATCC 750 and Candida maltosa. Both genes were individually expressed in a cpr mutant of Saccharomyces cerevisiae with high CPR activities, in which only a small distinction was observed between recombinant CPR‐a and CPR‐b. Both CPR‐a and CPR‐b contain one CTG codon, which codes for serine (amino acid 50) in C. tropicalis rather than universal leucine. A mutated cDNA of CPR‐a with a TCG codon instead of CTG codon was constructed and expressed, resulting in little increase in CPR activity. This indicates that the alteration of Ser‐50 has little effect on functional expression of CPR. Furthermore, high ketoconazole sensitivity for the cpr mutant was complemented by heterologous expression of the cloned CPR‐a or CPR‐b. The sequences of CPR‐a and CPR‐b have been submitted to DDBJ/EMBL/GeneBank databases under Accession Nos AY705446 and AY823228, respectively. Copyright © 2005 John Wiley & Sons, Ltd.
The acoustic target strength of herring (Clupea harengus L.) in the northern Baltic Sea
Authors: Peltonen Heikki , Balk Helge 
Published: April 2005

Abstract
The hydro-acoustic target strength (TS) of herring (Clupea harengus L.) was estimated from the catch composition of 19 pelagic-trawl hauls and from simultaneous recordings with a split-beam, 38 kHz echosounder. The data were collected in September 2000 during a Bothnian Sea survey in the northern Baltic Sea. The dependence of TS (in dB) on fish length (L, cm) was modelled with the equation TS = a log10 L + b. The fitted model was TS = 16.8 log10 L − 60.0. With a predefined slope of 20 the TS vs. log-fish length relationship was TS = 20 log10 L − 63.9. The analyses suggested that TS was higher in the Bothnian Sea than is assumed in most studies in the Baltic Sea. Applying the revised TS–length dependence considerably enhanced the agreement between the biomass estimates from hydroacoustics and those from a catche-at-age analysis (VPA).
Damage mechanisms and failure modes of cortical bone under components of physiological loading
Authors: George W. T. , Vashishth D. 
Published: April 2005

AbstractFatigue damage development in cortical bone was investigated in vitro under different mechanical components of physiological loading including tension, compression, and torsion. During each test, stress and strain data were collected continuously to monitor and statistically determine the occurrence of the primary, secondary, and tertiary stages associated with fatigue and/or creep failure of bone. The resultant microdamage and failure modes were identified by histological and fractographic analysis, respectively. The tensile group demonstrated Mode I cracking and the three classic stages of fatigue and creep suggesting a low crack initiation threshold, steady crack propagation and final failure by coalescence of microcracks. In contrast, the compressive group displayed Mode II cracking and a two‐stage fatigue behavior with limited creep suggesting a high crack initiation threshold followed by a sudden fracture. The torsion group also displayed a two‐stage fatigue profile but demonstrated extensive damage from mixed mode (Modes II and III) microcracking and predominant time‐dependant damage. Thus, fatigue behavior of bone was found to be uniquely related to the individual mechanical components of physiological loading and the latter determined the specific damage mechanisms associated with fatigue fracture. © 2005 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
IBZM-SPECT imaging of dopamine D2 receptors with typical and atypical antipsychotics
Authors: Kasper S , Tauscher J , Küfferle E , Hesselmann B , Barnas C , Brücke T 
Published: April 2005

SummaryConsiderable progress has been achieved over the past 15 years in uncovering the biological basis of major psychiatric disorders. Since psychopharmacological treatment is thought tc act on the underlying biological basis of the disease, brain imaging techniques enable us to understand the mechanism of action of such compounds. One important tool used to determine patterns of brain dysfunction and how psychopharmacological agents such as antipsychotic compounds work is single-photon emission computerised tomography (SPECT). This technique allows determination of striatal D2 receptor occupancy rates, which are associated with the extrapyramidal side effects (EPS) of antipsychotic drugs. Studies have confirmed that atypical antipsychotic agents have lower occupancy rates than typical agents. No association has been found between D2 receptor occupancy rates n the striatum and antipsychotic efficacy, and it therefore appears that striatal D2 receptor occupancy rates are not necessary for the antipsychotic effect of such agents in schizophrenia. The availability of more refined radioligands will help us not only to understand the action of antipsychotics but also the pathophysiology of schizophrenia.