bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and characterization of organoclay nanocomposites based on natural rubber
Authors: López‐Manchado MA , Herrero B , Arroyo M 
Published: June 2003

AbstractRubber compounds based on natural rubber (NR) reinforced with octadecylamine‐modified bentonite have been prepared via a vulcanization process and characterized by several techniques. The silicate nanolayers are exfoliated and uniformly dispersed in the polymer chains. Monsanto measurements have shown that the organoclay accelerates the vulcanization reaction and, furthermore, gives rise to a marked increase of the torque, indicating that the elastomer becomes more crosslinked in the presence of the organoclay. These results were corrobated by swelling measurements since a noticeable increase in the curing degree was observed when the organoclay was added to the rubber recipe. Moreover, thermodynamic parameters have shown an increase in the structural order of the nanocomposite. In addition, thermal analysis supports the assumption that the degree of curing of the elastomer increases when the organoclay is added to the elastomer. An appreciable increase of the involved heat during the curing reaction has been observed. Moreover, the Tg of the NR increases in the presence of the organoclay due to the confinement of the elastomer segment into the organoclay nanolayers, which restricts the mobility of the chains. Copyright © 2003 Society of Chemical Industry
Soft immobilized pH gradient gels in proteome analysis: A follow‐up
Authors: Bruschi Maurizio , Musante Luca , Candiano Giovanni , Ghiggeri Gian Marco , Herbert Ben , Antonucci Francesca , Righetti Pier Giorgio 
Published: June 2003

AbstractAs a follow‐up of a previous work on two‐dimensional map analysis utilizing soft (< 4%T) immobilized pH gradient (IPG) matrices in the first dimension (Candiano et al., Electrophoresis 2002, 23, 292–297), we have further optimized the preparation of such dilute IPG gels. One important step for obtaining an even reswelling of the entire IPG strip along the pH 3–10 interval is a washing step in 100 mM citric acid. It appears as though after rinsing off the excess acid in distilled water, a gradient of this tricarboxylic acid remains trapped into the IPG matrix, from almost nil at the acidic gel region to substantially higher amounts in its basic counterpart. This gradient helps in obtaining a uniform reswelling of the IPG strip, since carboxyl groups are more heavily hydrated than amino groups. The combined effects of uniform reswelling and of diluting the gel matrix favor penetration of large macromolecules (> 200 kDa) and allow for better spot resolution and for the display of a substantially higher number of spots also in the 30–60 000 Da region. A delipidation step in tri‐n‐butylphosphate:acetone:methanol (1:12:1) appears to substantially improve spot focusing and greatly diminish streaking and smearing of spots in all regions of the pH gradient.
Identification of new celiac disease autoantigens using proteomic analysis
Authors: Stulík Jiří , Hernychová Lenka , Porkertová Stanislava , Pozler Oldřich , Tučková Ludmila , Sánchez Daniel , Bureš Jan 
Published: June 2003

AbstractCeliac disease is an autoimmune disorder in which gluten peptides presented by specific HLA‐DQ2‐ and HLA‐DQ8‐positive antigen presenting cells elicit immune response in connective tissue of lamina propria. Immunoglobulin A (IgA) antiendomysial antibodies are specific for celiac disease and are used for screening, diagnosis and follow‐up of this disease with an almost 100% sensitivity and specificity. The major target antigen of IgA antiendomysial antibodies was identified as tissue transglutaminase; nevertheless, the existence of the additional unique celiac disease‐specific autoantigens is anticipated. In this study we have utilized a proteomic approach in order to search out new autoantigens recognized by serum antibodies of patients with active celiac disease. We report the detection of 11 proteins that were immunorecognized with various frequencies by sera of patients with celiac disease. Four autoantigens were identified by mass fingerprinting approach as actin, ATP synthase β chain and two charge variants of enolase α. While production of IgA antibodies against actin molecules were described earlier, the existence of autoantibodies to ATP synthase β chain and enolase α species in sera collected from patients with active celiac disease are described for the first time. These results are suggestive of the existence of additional celiac disease autoantigens with possible diagnostic utility.
An approach to the proteomic analysis of a breast cancer cell line (SKBR‐3)
Authors: Wu Shiaw‐Lin , Hancock William S. , Goodrich Geoffrey G. , Kunitake Steven T. 
Published: June 2003

AbstractThis report describes the profiling of proteins in a sample prepared by laser capture microdissection (LCM) from a breast cancer cell line (SKBR‐3). This experimental approach serves as a model system for proteomic studies on selected tissue samples and for studies of specific cell types. The captured cells were isolated in a dehydrated and reduced state and solubilized with a denaturing buffer. After dilution the protein mixture was digested with trypsin and the resulting peptide mixture was fractionated by reversed phase HPLC (RPLC) and analyzed on an ion trap mass spectrometer. A key part of this study is the combination of the LCM process with an extraction/digestion procedure that allowed effective solubilization of a significant part of the cellular sample in a single step. The identity of the peptides was determined by tandem mass spectrometry measurements in which the resulting spectra were compared with genomic and proteomic databases and protein identifications were made. While only peptides with a high probability assignment were used, the interpretation of mass spectral fragmentation patterns were also confirmed by manual interpretation of the spectra. Also, for the more abundant proteins the initial protein assignment from the best match peptide was strengthened by the observation of additional confirmatory peptide identifications. Another selection criteria was correlation of the mass spectrometric studies with clinical and genomic studies of potential cancer markers in tumor samples. This proteomic study allowed identification of the following proteins: human receptor protein kinase HER‐2 or ERBB‐2 and related kinases HER‐3 and HER‐4, the gene products from breast cancer type I and II susceptibility genes and cytoskeletal components such as cytokeratins 8, 18 and 19. Other proteins include fibroblast growth factor receptor variants (FGFR‐2&4) and T‐lymphoma invasion and metastasis inducing protein 1 (TIAM1). In addition several nonreceptor protein kinases YES, FAK and JAK‐1 and 3 were identified. Since the study was performed on a limited number of cells (approximately 10 000) it raises the possibility of such studies being performed on individual patient samples prepared by needle biopsy.
Using statistical image models for objective evaluation of spot detection in two‐dimensional gels
Authors: Rogers Mike , Graham Jim , Tonge Robert P. 
Published: June 2003

AbstractProtein spot detection is central to the analysis of two‐dimensional electrophoresis gel images. There are many commercially available packages, each implementing a protein spot detection algorithm. Despite this, there have been relatively few studies comparing the performance characteristics of the different packages. This is in part due to the fact that different packages employ different sets of user‐adjustable parameters. It is also partly due to the fact that the images are complex. To carry out an evaluation, “ground truth” data specifying spot position, shape and intensities needs to be defined subjectively on selected test images. We address this problem by proposing a method of evaluation using synthetic images with unambiguous interpretation. The characteristics of the spots in the synthetic images are determined from statistical models of the shape, intensity, size, spread and location of real spot data. The distribution of parameters is described using a Gaussian mixture model obtained from training images. The synthetic images allow us to investigate the effects of individual image properties, such as signal‐to‐noise ratios and degree of spot overlap, by measuring quantifiable outcomes, e.g. accuracy of spot position, false positive and false negative detection. We illustrate the approach by carrying out quantitative evaluations of spot detection on a number of widely used analysis packages.
Mapping of proteins in human saliva using two‐dimensional gel electrophoresis and peptide mass fingerprinting
Authors: Ghafouri Bijar , Tagesson Christer , Lindahl Mats 
Published: June 2003

AbstractHuman saliva contains a large number of proteins that can be used for diagnosis and are of great potential in clinical and epidemiological research. The aim of this work was to map the proteins in saliva by two‐dimensional gel electrophoresis (2‐DE), and to identify abundant proteins by peptide mass fingerprinting using trypsin cleavage and matrix‐assisted laser desorption/ionization‐time of flight‐mass spectrometry analysis. One hundred proteins were identified representing 20 different identities according to accession numbers. Abundant proteins expressed in different forms were: α‐amylase, immunoglobulin A, prolactin‐inducible protein, zinc‐α2‐glycoprotein and cystatins (S, SA, D and SN). Other proteins found were interleukin‐1 receptor antagonist, von Ebner’s gland protein (lipocalin‐1) and calgranulin A and B (S100A8 and A9). Furthermore, apolipoprotein A‐I, β2‐microglobulin, glutathione S‐transferase P and fatty acid‐binding protein were also identified. Our results show that human saliva contains a large number of proteins that are involved in inflammatory and immune responses. The 2‐DE protein map constructed opens the possibility to investigate protein changes associated with disease processes.
Proteome analysis of aerobic and fermentative metabolism in Rhizobium etli CE3
Authors: Encarnación Sergio , Guzmán Yudith , Dunn Michael F. , Hernández Magdalena , Vargas Maria del Carmen , Mora Jaime 
Published: June 2003

AbstractRhizobium etli undergoes a transition from an aerobic to a fermentative metabolism during successive subcultures in minimal medium. This metabolic transition does not occur in cells subcultured in rich medium, or in minimal medium containing either biotin or thiamine. In this report, we characterize the aerobic and fermentative metabolism of R. etli using proteome analysis. According to their synthesis patterns in response to aerobic (rich medium, minimal medium with biotin or minimal medium with thiamine) or fermentative (minimal medium without supplements) growth conditions, proteins were assigned to five different classes: (i) proteins produced only in aerobic conditions (e.g., catalase‐peroxidase KatG and the E2 component of pyruvate dehydrogenase); (ii) protein produced under both conditions but strongly induced in aerobic metabolism (e.g., malate dehydrogenase and the succinyl‐CoA synthetase β subunit); (iii) proteins that were induced equally under all conditions tested (e.g., AniA, DnaK, and GroEL); (iv) proteins downregulated during aerobic metabolism, and (v) proteins specific to only one of the conditions analyzed. Northern blotting studies of katG expression confirmed the proteome data for this protein. The negative regulation of carbon metabolism proteins observed in fermentative metabolism is consistent with the drastic physiological changes which occur during this process.
Morphology, structure, and properties of in situ compatibilized linear low‐density polyethylene/polystyrene and linear low‐density polyethylene/high‐impact polystyrene blends
Authors: Gao Ying , Huang Honglian , Yao Zhanhai , Shi Dean , Ke Zhuo , Yin Jinghua 
Published: June 2003

AbstractBlends of linear low‐density polyethylene (LLDPE) with polystyrene (PS) and blends of LLDPE with high‐impact polystyrene (HIPS) were prepared through a reactive extrusion method. For increased compatibility of the two blending components, a Lewis acid catalyst, aluminum chloride (AlCl3), was adopted to initiate the Friedel–Crafts alkylation reaction between the blending components. Spectra data from Raman spectra of the LLDPE/PS/AlCl3 blends extracted with tetrahydrofuran verified that LLDPE segments were grafted to the para position of the benzene rings of PS, and this confirmed the graft structure of the Friedel–Crafts reaction between the polyolefin and PS. Because the in situ generated LLDPE‐g‐PS and LLDPE‐g‐HIPS copolymers acted as compatibilizers in the relative blending systems, the mechanical properties of the LLDPE/PS and LLDPE/HIPS blending systems were greatly improved. For example, after compatibilization, the Izod impact strength of an LLDPE/PS blend (80/20 w/w) was increased from 88.5 to 401.6 J/m, and its elongation at break increased from 370 to 790%. For an LLDPE/HIPS (60/40 w/w) blend, its Charpy impact strength was increased from 284.2 to 495.8 kJ/m2. Scanning electron microscopy micrographs showed that the size of the domains decreased from 4–5 to less than 1 μm, depending on the content of added AlCl3. The crystallization behavior of the LLDPE/PS blend was investigated with differential scanning calorimetry. Fractionated crystallization phenomena were noticed because of the reduction in the size of the LLDPE droplets. The melt‐flow rate of the blending system depended on the competition of the grafting reaction of LLDPE with PS and the degradation of the blending components. The degradation of PS only happened during the alkylation reaction between LLDPE and PS. Gel permeation chromatography showed that the alkylation reaction increased the molecular weight of the blend polymer. The low molecular weight part disappeared with reactive blending. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1837–1849, 2003
Attitudes, knowledge, risk perceptions and decision‐making among women with breast and/or ovarian cancer considering testing for BRCA1 and BRCA2 and their spouses
Authors: Bluman Leslie G. , Rimer Barbara K. , Sterba Katherine Regan , Lancaster Julia , Clark Shelly , Borstelmann Nancy , Iglehart J. Dirk , Winer Eric P. 
Published: June 2003

AbstractA limited number of studies have examined the involvement of spouses in the decision‐making process for genetic testing as well as impact of the actual testing. This report presents data from 40 women with a personal history of breast and/or ovarian cancer who were considering genetic testing for BRCA1 and BRCA2 and their spouses. We examined knowledge and attitudes regarding genetic testing for breast cancer susceptibility, perceptions of the likelihood that their wives (the women) had a BRCA1 or BRCA2 mutation, pros and cons of genetic testing, spouses' satisfaction with their involvement in the decision‐making process and additional resources they would find helpful. Knowledge about cancer genetics and genetic testing for BRCA1 and BCA2 was limited among both women and their spouses. Up to one‐third of spouses indicated that they would like to avail themselves of additional sources of information about BRCA1 and BRCA2 testing. Most spouses indicated that they thought their wives had a mutation in BRCA1 or BRCA2 and that their wives' breast cancers would recur. Pros of genetic testing were emphasized more than cons among both parties. Overall, spouses were satisfied with their role in the decision‐making process. Future interventions to improve the decision‐making process regarding genetic testing for breast cancer susceptibility should be undertaken. Copyright © 2003 John Wiley & Sons, Ltd.
The role of religious coping in adjustment to cancer
Authors: Nairn Raymond C. , Merluzzi Thomas V. 
Published: June 2003

AbstractThis study tested a model of adjustment to cancer in which social support, disease impact, and religious coping were hypothesized to have an impact on adjustment to cancer that was mediated by self‐efficacy. Two hundred and ninety‐two people with cancer completed questionnaires. Three analyses were undertaken: first, the structure of the Religious Problem Solving Scale was assessed by a factor analysis in which two factors emerged, Deferring–Collaborative and Self‐Directing; second, the resulting factors' relationships to outcome measures were assessed through correlational and regression analyses; third, a mediated model of coping was tested with self‐efficacy as a mediating variable between religious coping and adjustment. The Deferring–Collaborative factor had positive relationships with most of the variables and was partially mediated by self‐efficacy. The results indicate that religious coping has no relationship to quality of life, a positive relationship with adjustment, and was more important in this study than available social support. Copyright © 2003 John Wiley & Sons, Ltd.
The quintic standard model
Authors: Körs B. 
Published: June 2003

AbstractWe consider brane world compactifications of type I string theory, where O‐planes and D‐branes are wrapped on supersymmetric cycles in Calabi‐Yau 3‐folds. General conditions for supersymmetric vacua are discussed and the concept of intersecting branes that break supersymmetry in a particular weak way is developed. It provides a setting in which one can very concretely engineer gauge groups and chiral fermion spectra according to the features of realistic low energy field theory models of particle interactions. For the example of the well known quintic Calabi‐Yau this is applied to produce a string compactification with Standard Model gauge group and three generation matter spectrum satisfying all string consistency requirements. We also add some comments on the status of anomaly cancellation via the Green‐Schwarz mechanism which is linked to the appearance of Stückelberg masses for abelian gauge bosons. Finally we demonstrate how the branes induce a scalar potential in the effective action via their tension, taking the form of an ${\cal N}=1$ D‐term.
Topological transitions and enhançon‐like geometries in Calabi‐Yau compactifications of M‐theory
Authors: Mohaupt T. 
Published: June 2003

AbstractWe study the impact of topological phase transitions of the internal Calabi‐Yau threefold on the space‐time geometry of five‐dimensional extremal black holes and black strings. For flop transitions and SU(2) gauge symmetry enhancement we show that solutions can always be continued and that the behaviour of metric, gauge fields and scalars can be characterized in a model independent way. Then we look at supersymmetric solutions which describe naked singularities rather than geometries with a horizon. For black strings we show that the solution cannot become singular as long as the scalar fields take values inside the Kähler cone. For black holes we establish the same result for the elliptic fibrations over the Hirzebruch surfaces ℱ0, ℱ1, ℱ2. These three models exhibit a behaviour similar to the enhançon, since one runs into SU(2) enhancement before reaching the apparent singularity. Using the proper continuation inside the enhançon radius one finds that the solution is regular.
Electrospray Ionization Tandem Mass Spectrometry in High‐Throughput Screening of Homogeneous Catalysts
Authors: Chen Peter 
Published: June 2003

AbstractThe frontispiece shows an illustration by John Tenniel and an excerpt from the 1865 edition of Lewis Carroll's “Alice in Wonderland”. Because everything in Wonderland runs counter to logic, the Queen of Hearts declares in Alice's trial “Sentence first—verdict afterwards”. High‐throughput screening of catalysts, as it is conventionally practiced, does “Synthesis first—screening afterwards” which, as is argued in this review, also backwards. Given the particular constraints present in organometallic complexes, it is more efficient to develop a selective synthesis only when it has already been determined that a structure is likely to be better. The consequence is that screening methods must be able to handle ill‐defined mixtures. Electrospray ionization tandem mass spectrometry is presented as a technical solution to this problem.
Recent Methods for the Synthesis of (E)‐Alkene Units in Macrocyclic Natural Products
Authors: Prunet Joëlle 
Published: June 2003

Abstract(E)‐Alkene units are frequently found in macrocyclic natural products. Among the reactions that form the double bond during the cyclization, the classical Horner–Emmons coupling is still frequently used with success. During the last decade, ring‐closing metathesis has emerged as a very powerful tool for the synthesis of large rings, but the E/Z selectivity, which is rarely predictable, depends on many factors which will be discussed in this review. The best solution might be a two‐step procedure involving ring‐closing alkyne metathesis (RCAM) followed by stereoselective reduction of the macrocyclic alkyne unit to the corresponding E double bond.
Recent developments in receptor modeling
Authors: Hopke Philip K. 
Published: June 2003

AbstractReceptor modeling is the application of data analysis methods to elicit information on the sources of air pollutants. Typically, it employs methods of solving the mixture resolution problem using chemical composition data for airborne particulate matter samples. In such cases, the outcome is the identification of the pollution source types and estimates of the contribution of each source type to the observed concentrations. It can also involve efforts to identify the locations of the sources through the use of ensembles of air parcel back trajectories. In recent years, there have been improvements in the factor analysis methods that are applied in receptor modeling as well as easier application of trajectory methods. These developments are reviewed. Copyright © 2003 John Wiley & Sons, Ltd.
1‐Octanol/Water Partition Coefficients of 1Alkyl‐3‐methylimidazolium Chloride
Authors: Domańska Urszula , Bogel‐Łukasik Ewa , Bogel‐Łukasik Rafał 
Published: June 2003

AbstractThe solubilities of 1alkyl‐3‐methylimidazolium chloride, [Cnmim][Cl], where n=4, 8, 10, and 12, in 1octanol and water have been measured by a dynamic method in the temperature range from 270 to 370 K. The solubility data was used to calculate the 1octanol/water partition coefficients as a function of temperature and alkyl substituent. The melting point, enthalpies of fusion, and enthalpies of solid–solid phase transitions were determined by differential scanning calorimetry, DSC. The solubility of [Cnmim][Cl], where n=10 or 12 in 1octanol is comparable and higher than that of [C4mim][Cl] in 1octanol. Liquid 1n‐octyl‐3‐methylimidazolium chloride, [C8mim][Cl], is not miscible with 1octanol and water, consequently, the liquid–liquid equilibrium, LLE was measured in this system. The differences between the solubilities in water for n=4 and 12 are shown only in α1 and γ1 solid crystalline phases. Additionally, the immiscibility region was observed for the higher concentration of [C10mim][Cl] in water. The intermolecular solute–solvent interaction of 1butyl‐3‐methylimidazolium chloride with water is higher than for other 1alkyl‐3‐methylimidazolium chlorides. The data was correlated by means of the UNIQUAC ASM and two modified NRTL equations utilizing parameters derived from the solid–liquid equilibrium, SLE. The root‐mean‐square deviations of the solubility temperatures for all calculated data are from 1.8 to 7 K and depend on the particular equation used. In the calculations, the existence of two solid–solid first‐order phase transitions in [C12mim][Cl] has also been taken into consideration. Experimental partition coefficients (log P) are negative at three temperatures; this is evidence for the possible use of these ionic liquids as green solvents.