bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prepolymerization of ethylene with a Ziegler–Natta catalyst
Authors: Mirzaei Ahmad , Vakili Mohammad , Tafi Neda 
Published: May 2007

AbstractThe slurry prepolymerization of ethylene using TiCl4/MgCl2 as a catalyst was investigated. A 23‐factorial experimental design method was employed to study the effects of the temperature, hydrogen, and active cocatalyst‐to‐catalyst molar ratio (Al/Ti) on the catalyst activity, prepolymer melt flow index, and powder bulk density. All dependent variables increased when the active Al/Ti ratio increased from 1 to 2. The hydrogen–Al/Ti interaction had a significant effect on the prepolymer melt flow index and catalyst activity. The hydrogen (partial pressure ranging from 0.5 to 1.5 bar) and temperature (ranging from 60 to 80°C) variables as well as the hydrogen–temperature and hydrogen–temperature–Al/Ti interactions increased the prepolymer powder bulk density, which ranged from 0.11 to 0.373 g/cc. To find the reason for the prepolymer powder bulk density variation with the operating conditions, the particle size distribution and crystallinity of the prepolymers were determined. The increasing catalyst activity, ranging from 132 to 660 g of polyethylene/mmol of Ti, enhanced the weight percentage of fines, which ranged from 3 to 60, and decreased the average particle size, which ranged from 562 to 120 μm. This was the reason for the increasing prepolymer powder bulk density and could be due to the breakup of the prepolymer particles during prepolymerization. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Affinity purification of plasmid DNA directly from crude bacterial cell lysates
Authors: Darby Richard A.J. , Forde Gareth M. , Slater Nigel K.H. , Hine Anna V. 
Published: May 2007

AbstractWe have shown previously that a sequence‐specific DNA‐binding protein based on the Lac repressor protein can isolate pre‐purified DNA efficiently from simple buffer solution but our attempts to purify plasmids directly from crude starting materials were disappointing with impractically low DNA yields. We have optimized the procedure and present a simple affinity methodology whereby plasmid DNA is purified directly by mixing two crude cell lysates, one cell lysate containing the plasmid and the other the protein affinity ligand, without the need for treatment by RNaseA. After IMAC chromatography, high purity supercoiled DNA is recovered in good yields of 100–150 µg plasmid per 200 mL shake flask culture. Moreover, the resulting DNA is free from linear or open‐circular plasmid DNA, genomic DNA, RNA, and protein, to the limits of our detection. Furthermore, we show that lyophilized affinity ligand can be stored at room temperature and re‐hydrated for use when required. Biotechnol. Bioeng. 2007;98: 1103–1108. © 2007 Wiley Periodicals, Inc.
Human endothelial cell growth and phenotypic expression on three dimensional poly(lactide‐co‐glycolide) sintered microsphere scaffolds for bone tissue engineering
Authors: Jabbarzadeh Ehsan , Jiang Tao , Deng Meng , Nair Lakshmi S. , Khan Yusuf M. , Laurencin Cato T. 
Published: May 2007

AbstractBone tissue engineering offers promising alternatives to repair and restore tissues. Our laboratory has employed poly(lactid‐co‐glycolide) PLAGA microspheres to develop a three dimensional (3‐D) porous bioresorbable scaffold with a biomimetic pore structure. Osseous healing and integration with the surrounding tissue depends in part on new blood vessel formation within the porous structure. Since endothelial cells play a key role in angiogenesis (formation of new blood vessels from pre‐existing vasculature), the purpose of this study was to better understand human endothelial cell attachment, viability, growth, and phenotypic expression on sintered PLAGA microsphere scaffold. Scanning electron microscopy (SEM) examination showed cells attaching to the surface of microspheres and bridging the pores between the microspheres. Cell proliferation studies indicated that cell number increased during early stages and reached a plateau between days 10 and 14. Immunofluorescent staining for actin showed that cells were proliferating three dimensionally through the scaffolds while staining for PECAM‐1 (platelet endothelial cell adhesion molecule) displayed typical localization at cell–cell contacts. Gene expression analysis showed that endothelial cells grown on PLAGA scaffolds maintained their normal characteristic phenotype. The cell proliferation and phenotypic expression were independent of scaffold pore architecture. These results demonstrate that PLAGA sintered microsphere scaffolds can support the growth and biological functions of human endothelial cells. The insights from this study should aid future studies aimed at enhancing angiogenesis in three dimensional tissue engineered scaffolds. Biotechnol. Bioeng. 2007;98: 1094–1102. © 2007 Wiley Periodicals, Inc.
Validated ion pair liquid chromatography/fluorescence detection method for assessing the variability of the loratadine metabolism occurring in bioequivalence studies
Authors: Sora Daniela Iuliana , Udrescu Stefan , David Victor , Medvedovici Andrei 
Published: May 2007

AbstractInter‐ and intra‐individual variability of the loratadine (LOR) metabolism in Caucasian subjects was assessed during a bioequivalence study for two pharmaceutical formulations (solid oral dosage forms) containing 10 mg of the active substance. The analytical data were obtained by applying a reliable, low‐cost and sensitive ion pair liquid chromatography/fluorescence (IPLC/FLD) method for determination of both loratadine and descarboethoxyloratadine (DCL) in human plasma samples. The sample preparation procedure is based on liquid–liquid extraction of the target analytes from alkalinized plasma using diethyl‐ether. The separation of the analytes and 8‐chloroazatadine as internal standard (IS) was achieved through an isocratic ion pair (IP) elution on a Purospher® STAR RP‐18 column. The mobile phase containing sodium dodecyl sulfate (SDS) as ion pairing agent was pumped at a flow rate of 1 mL/min. Fluorescence detection (FLD) was achieved at 280 nm (excitation) and 440 nm (emission) wavelengths. The increased sensitivity of the method is also based on a large sample injected volume (250 µL). Linear response was found over the 0.5–20 ng/mL concentration interval for both target compounds. Low limits of quantification (LLOQ) around 0.3 ng/mL were found for LOR and DCL. Method validation is presented. Copyright © 2007 John Wiley & Sons, Ltd.
Exploration of Backbone Space in Foldamers Containing α‐ and β‐Amino Acid Residues: Developing Protease‐Resistant Oligomers that Bind Tightly to the BH3‐Recognition Cleft of Bcl‐xL
Authors: Sadowsky Jack D. , Murray Justin K. , Tomita York , Gellman Samuel H. 
Published: May 2007

AbstractProtein–protein interactions play crucial roles in cell‐signaling events and are often implicated in human disease. Molecules that bind tightly to functional protein‐surface sites and show high stability to degradative enzymes could be valuable pharmacological tools for dissection of cell‐signaling networks and might ultimately lead to therapeutic agents. We recently described oligomers containing both α‐ and β‐amino acid residues that bind tightly to the BH3 recognition site of the anti‐apoptotic protein Bcl‐xL. The oligomers with highest affinity had a nine‐residue N‐terminal segment with a 1:1 α:β residue repeat and a six‐residue C‐terminal segment containing exclusively proteinogenic α‐residues. The N‐terminal portions of such (α/β+α)‐peptides are highly resistant to proteolysis, but the C‐terminal α‐segments are susceptible. This study emerged from efforts to modify the α‐segment in an (α/β+α)‐peptide in a way that would diminish proteolytic degradation but retain high affinity for Bcl‐xL. Some of the oligomers reported here could prove useful in certain biological applications, particularly those for which extended incubation in a biological milieu is required.
HeLa Cell Entry by Guanidinium‐Rich β‐Peptides: Importance of Specific Cation–Cell Surface Interactions
Authors: Potocky Terra B. , Silvius John , Menon Anant K. , Gellman Samuel H. 
Published: May 2007

AbstractShort cationic oligomers, including arginine‐rich peptides and analogous β‐amino acid oligomers (“β‐peptides”), can enter the cytoplasm and nucleus of a living cell from the extracellular medium. It seems increasingly clear that multiple entry pathways are possible, depending upon the structure of the guanidinium‐rich molecule, the type of cell, and other factors. We have previously shown that conformational stability and spatial clustering of guanidinium groups increase the HeLa cell entry efficiency of short helical β‐peptides bearing six guanidinium groups, results that suggest that these β‐peptides could be useful tools for studying the entry process. Here we describe studies intended to identify the point in the entry process at which helix stability and spatial arrangement of guanidinium groups exert their effect. Our results suggest that key distinctions involve the mode of interaction between different guanidinium‐rich β‐peptides and the HeLa cell surface. A specific guanidinium display appears to be required for proper engagement of cell‐surface heparan sulfate proteoglycans and concomitant induction of endocytic uptake.
Experimental study of group creativity: Task representation, group structure, and performance
Authors: Abric J.‐C. 
Published: May 2007

AbstractThis article attempts to introduce and investigate a new variable in the experimental study of groups: the representation system. This study deals more specifically with the riile played by the representation of the task. This representation of the task constitutes the theory, the system of hypotheses individuals work out with respect to the nature of the task and the means to use in order to carry it out.The key results of this study are that group performance depends on the representation of the task, with optimum effectiveness achieved when the representation of the task and its objective nature coincide. Another finding is that the structure of communications within the group is determined by the representation of the task rather than by its objective character. It was also established that the representation of the task determines the cognitive process adopted by the group. Thus the entire group activity is tied to the representations in its midst. The group organizes itself, regulates itself interactions, and determines its priorities in terms of these representations.
The effect of judges' attitudes on ratings of attitude statements. A theoretical analysis
Authors: Stroebe Wolfgang 
Published: May 2007

AbstractJudgments of attitude statements with the method of equal‐appearing intervals have been found to vary as a function of the judges' attitudes. In this paper explanations of the relationship between judges' attitudes and judgments of attitude statements in terms of models of psychophysical judgment are discussed. It is argued that psychophysical models such as adaptation‐level theory, the range‐frequency model, and the ‘rubber‐band’ model and its derivations, cannot account satisfactorily for judges' performance of the attitude rating task in a great number of studies. The reason for this failure, it is argued, is that the stimulus series employed in the psychophysical judgment research on which these models are based typically varied only on the dimension being judged. The sets of statements judged in attitude rating studies, however, vary not only on the dimension of interest (favourability—Unfavourability) but also on a number of other dimensions. It is suggested that this incidental stimulus variation of attitude statements may account for the failure of psychophysical models to predict accurately the performance of judges in the attitude rating task. It is argued that if principles which could account for the effects of this incidental stimulus variation on attitude ratings could be incorporated into psychophysical models, the predictive qualities of these models could be improved considerably. One such model is discussed.
Group risk‐taking and group polarization
Authors: Fraser Colin 
Published: May 2007

AbstractThere are two aims to this paper; to report in brief preliminary form a number of studies on group risk‐taking that have been carried out in Bristol in the past two years, and to relate these studies to an explanation of group risk‐taking phenomena primarily in terms of group polarization. The paper has five sections. The first section supplies some background material regarding basic phenomena and previous attempts at explanations. The second section relates to initial individual decisions and the third section to decisions following group discussion and consensus. In the fourth section a tentative explanation of group risk‐taking effects is proposed in terms of group polarization processes, together with something like an overall value for risk. Group polarization itself is discussed in terms of normative and informational aspects of social influence. The final section deals with two implications of the proposed explanation, one relating to the role of individual familiarization and the other to the generality of group polarization processes.
The relationship between riskiness and confidence in choice dilemma decisions
Authors: Stroebe Wolfgang , Fraser Colin 
Published: May 2007

AbstractThe relationship between riskiness of decisions and confidence in decisions was examined using Choice Dilemma items. Graphs show a clear curvilinear relationship between riskiness and confidence; on both risky items and cautious items greater confidence is associate with extremely risky and extremely cautious decisions than with moderate ones. it was also demonstrated that individual subjects have more confidence in their extreme decisions than in their moderate ones.
Single linear ordering versus multiple discrepant orderings in the cognitive representation of social structures
Authors: Kahan James P. , Poitou Jean‐Pierre 
Published: May 2007

AbstractPrevious studies have assumed that people have a predilection for single linear orderings, of which status congruence is a special case. Eighty‐two subjects were run in a two‐stage experiment to examine preference for linear orderings and whether single or multiple discrepant orderings are preferred when 1 instead of having to learn, subjects freely construct social structures, and 2 the material they are presented is more specified and less simplified than is usually the case in cognitive bias studies. In the first stage Ss were presented with sets of five individual characteristic dimensions, of which three were inherently orderable. Their task was to attribute one characteristic from each dimension to each of five fictitious persons. In the second stage, Ss were asked, for three types of influence (professional, political and cultural), to build an influence structure among the five persons constructed in the first stage.In Stage 1, linear ordering was used for three of the five dimensions. Two of these dimensions used a single ordering, while the third was only weakly related to the first two. In Stage 2, largely transitive but incomplete relations of influence were established, based on a salary‐occupational hierarchy. The completeness of the relation depended on the nature of the influence.
The durations of attention to alternatives and re‐evaluation in choices with two and three alternatives
Authors: East Robert 
Published: May 2007

AbstractIn two experiments on choice the durations of attention to the alternatives were measured. In experiment 1 each subject chose one from two pictures; in experiment 2 the choice was one from three pictures. In both experiments the subjects understood that they would acquire the picture that they selected. In each experiment higher and lower conflict conditions were induced by offering subjects a choice between alternatives that had been evaluated either equally or disparately.In both experiments a significant relationship appeared between duration of attention and preference order with most subjects looking longest at the alternative that was preferred.In the comparison between conditions this effect was found to be stronger under lower conflict than under higher conflict; this difference reached a significant level in experiment 2. These results are contrary to findings by Gerard (1967), and this matter is discussed. The relevance of the results to other theories is examined.Inferences were drawn from dissonance theory about re‐evaluation effects after decision, and evaluation changes were measured in the experiments. After adjustment for measurement regression, the data failed to reveal a significant chronic re‐evaluation effect. Contrary to dissonance theory, the re‐evaluation effect was weaker in the three‐alternative choice experiment than in the two‐alternative choice experiment.
An experimental method for inquiring into communication
Authors: Blakar Rolv Mikkel 
Published: May 2007

AbstractAn experimental method for inquiring into the organization of an act of communication is presented, the basic idea being to create an interactional setting where one of the basic prerequisites for successful communication is not satisfied. In this particular design, the subjects interact under the false belief that they are sharing the same ‚here'. (In mean the subjects interacted more than a quarter of an hour before any doubt or suspicion about the situation was expressed, indicating that our manipulation had been successful.) During the subjects trying (1) to ‚diagnose' their communicative difficulties, and (2) to apply different ‚therapeutic tools' in order to improve their communication, one is in a very good position to study the impact from a variety of basic phenomena upon communication. It is argued that this situation may well be applied as a ‚standard experimental method'. And an experiment where this method revealed interesting differences in the communication between couples having and couples not having a schizophrenic offspring is discussed.
Patterning of the minority's responses and their influence on the majority
Authors: Nemeth Charlan , Swedlund Mark , Kanki Barbara 
Published: May 2007

AbstractIn reaction to the decades of research that tended to assume that social influence is synonymous with conformity, recent work has concentrated on the ability of a minority, by having a system of answers of its own, to influence the majority in the direction of their judgments. A study by Moscovici, Lage and Naffrechoux (1969) demonstrated this phenomenon but found that consistency of response, in the sense of repetition, was necessary for minority influence to be effected. They assumed that repetition was necessary to give the minority judgment the same value as that of the majority and to intensify the conflict that was engendered by the differences in opinion. Our position is that the lack of repetition in that study was construed to mean that the minority did not really have a position in which they were confident. As such, they were discounted. Thus, it is the attribution of consistency and confidence that leads to minority influence, not intensification of the conflict. The present study found that non‐repetitious behavior by a minority could be seen as reflecting consistency and confidence and could lead to minority influence provided the inconsistency was patterned with some property of the stimulus. Such ‘inconsistency’ was perceived as favorable and as effective as any other condition and even more effective than one of the repetitious conditions.
Proteins involved in neuronal differentiation of neuroblastoma cell line N1E‐115
Authors: Oh Ji‐eun , Freilinger Angelika , Gelpi Ellen , Pollak Arnold , Hengstschläger Markus , Lubec Gert 
Published: May 2007

AbstractNeuronal differentiation (ND) represents a well‐defined phenomenon in biological terms but proteins involved have not been studied systematically. We therefore aimed to study ND by retinoic acid (RA) in a widely used neuroblastoma cell line by comparative proteomics. The ND was induced in the N1E‐115 cell line by serum deprivation and RA treatment. Undifferentiated cells and cells undergoing serum deprivation served as controls. Protein extracts were run on 2‐DE followed by MALDI‐TOF or MALDI‐TOF‐TOF analysis. Quantification was carried out using specific software and stringent statistical analysis was performed. Tubulin beta 5, cat eye syndrome critical region protein 5 homolog, putative GTP‐binding protein PTD004 homolog, and the metabolic proteins glyceraldehyde‐3‐phosphate dehydrogenase and transketolase were differentially regulated. Differential protein levels of cytoskeleton proteins including tubulins and metabolic proteins have been reported to be regulated by ND. Herein, specific signaling differences as reflected by putative GTP‐binding protein PTD004 changes in differentiated cells are shown and a possible role for the Cat eye syndrome critical region protein 5 homolog is proposed. The protein disulfide isomerase associated 3 protein fits the already proposed findings of chaperon regulation by ND. The study forms the molecular basis for further evaluation of the functional roles of the differentially expressed proteins in ND.
Assessment of natural and synthetic wollastonite as source for bioceramics preparation
Authors: Carrodeguas R. G. , De Aza A. H. , De Aza P. N. , Baudín C. , Jiménez J. , López‐Bravo A. , Pena P. , De Aza S. 
Published: May 2007

AbstractPseudowollastonite ceramics (β‐CaSiO3) from synthetic and natural sources were assessed with regard to their properties relevant to biomedical applications. Synthetic and natural CaSiO3 powders, with average particle size of 1.6 and 13.2 μm, respectively, were first employed. Powders were pressed and sintered at 1400°C for 2 h. Pseudowollastonite was the only crystalline phase in sintered materials. Glassy phase, eight times more abundant in sintered natural wollastonite (SNW) than in the synthetic one (SSW), was observed in grain boundaries and in triple points. Larger grains and bigger and more abundant pores were present in SNW, resulting in lower diametral tensile strength (26 MPa), than in SSW (42 MPa). However, by milling the natural wollastonite starting powder to a particle size of 2.0 μm and sintering (SNW‐M), the microstructure became finer and less porous, and diametral tensile strength increased (48 MPa). Weibull modulus of SNW and SNW‐M samples was twice that of the SSW. All the samples released Si and Ca ions, and removed phosphate ions from simulated body fluid in similar amounts and were completely coated by apatite‐like spherules after soaking in simulated body fluid for 3 wk. The aqueous extracts from all samples studied were not cytotoxic in a culture of human fibroblastic cells. No differences in fibroblast‐like human cells adhesion and proliferation were observed between samples. According to the obtained results, properly processed pseudowollastonite bioceramics, obtained from the natural source, exhibit the same in vitro behavior and better performance in terms of strength and reliability than do the more expensive synthetic materials. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007