bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of thioether derivatives of brominated poly(isobutylene‐co‐isoprene): Direct coupling chemistry for silica reinforcement
Authors: Parent J. Scott , White Greg D. F. , Whitney Ralph A. 
Published: October 2002

AbstractThioether derivatives of brominated poly(isobutylene‐co‐isoprene) (BIIR) were prepared through base‐mediated nucleophilic substitution reactions of the elastomer with thiolate ions formed in situ from thiols. The characterization of the reaction products was accomplished with studies of a model compound, brominated 2,2,4,8,8‐pentamethyl‐4‐nonene, the reactivity of which was shown to be consistent with that of the polymer. The reaction of aliphatic thiols with the allylic bromide functionality of BIIR required a strong base, and base‐catalyzed air oxidation of the thiol to disulfide operated concurrently to reduce the yield of the desired substitution products. An efficient and direct method of coupling BIIR to silica with (3‐mercaptopropyl)trimethoxysilane improved filler dispersion, thereby overcoming problematic agglomeration of reinforcing siliceous fillers in these compounds. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2937–2944, 2002
Polymerizable benzophenone derivatives for labeling vinyl acetate‐butylacrylate latex particles
Authors: Oh Jung Kwon , Wu Jun , Winnik Mitchell A. , Craun Gary P. , Rademacher Jude , Farwaha Rajeev 
Published: October 2002

AbstractWe describe the synthesis and characterization of three new polymerizable benzophenone derivatives [2‐acryloxy‐5‐methyl benzophenone (8), 4′‐dimethylamino‐2‐acryloxy‐5‐methyl benzophenone (9), and 4′‐dimethylamino‐2‐(β‐acryloxyethyl)oxy‐5‐methyl benzophenone (10)]. We show that these monomers can successfully be incorporated into vinyl acetate (VAc) copolymer latex particles. These particles were prepared by semicontinuous emulsion polymerization and mini‐emulsion polymerization of VAc with butylacrylate (BA) for VAc/BA = 4/1 by weight. The two monomers 9 and 10 bearing the 4′‐dimethylamino group satisfy the important spectroscopic criteria required of a dye to serve as an acceptor chromophore for nonradiative energy transfer from phenanthrene (Phe) as the donor. Their UV absorption spectra suggest significant overlap with the emission spectrum of Phe, which can be incorporated into P(VAc‐co‐BA) latex through copolymerization with 9‐acryloxymethyl Phe (2). In addition, these chromophores provide a window in their absorption spectra for excitation of the Phe chromophore at 300 nm. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3001–3011, 2002
Atom transfer radical polymerization of styrene in toluene/water mixtures
Authors: Sarbu Traian , Pintauer Tomislav , McKenzie Blayne , Matyjaszewski Krzysztof 
Published: October 2002

AbstractThe atom transfer radical polymerization (ATRP) of styrene in water/toluene mixtures was studied. A linear dependence of the molecular weight on conversion was observed, but the initiation efficiency decreased when the catalyst concentration increased. The variation of the amount of water in the system affected the control of the ATRP, indicating that the presence of the aqueous phase influenced the concentration of copper halides in the organic phase. The partitioning of copper halides resulted in almost complete migration of CuII into the aqueous phase, which assisted with catalyst removal after polymerization. For example, the amount of residual copper in the organic phase determined by inductively coupled plasma was less than 1 ppm when the polymerization mixture was exposed to air for 30 min. The ATRP of styrene in water/toluene mixtures occurred with the preservation of Br at the polymer chain end, as confirmed by successful block copolymerization. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3153–3160, 2002
Rheological properties of diblock copolymer/layered‐silicate nanocomposites
Authors: Mitchell Cynthia A. , Krishnamoorti Ramanan 
Published: October 2002

AbstractThe melt‐state viscoelastic properties of nanocomposites prepared with a symmetrical polystyrene–polyisoprene block copolymer and organically modified layered silicates are examined. Nanocomposites based on three thermodynamically equivalent organically modified layered silicates, primarily differing in lateral disk diameter (d), are studied with small‐amplitude oscillatory shear. The effects of the domain structure of the ordered block copolymer and the mesoscale dispersion of the layered silicates on the rheological properties are examined via a comparison of data for the nanocomposites in the ordered and disordered states of the block copolymer. Hybrids prepared with 5 wt % organically modified fluorohectorite (d ∼ 10 μm) and montmorillonite (d ∼ 1 μm) demonstrate a notable decrease in the frequency dependence of the moduli at low frequencies and a significant enhancement in the complex viscosity at low frequencies in the disordered state. This behavior is understood in terms of the development of a percolated layered‐silicate network structure. However, the viscoelastic properties in the disordered state with 5 wt % organically modified laponite (d ∼ 30 nm) and in the ordered state of the block copolymer for all layered silicates demonstrate only minor changes from those observed for the unfilled polymer. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1434–1443, 2002
Intrinsic birefringence of poly(trimethylene terephthalate)
Authors: Chuah Hoe H. 
Published: October 2002

AbstractHighly oriented poly(trimethylene terephthalate) (PTT) fiber has a low birefringence that is unexpected for an aromatic polyester with a high refractive index. To explain this observation, the intrinsic birefringence Δn of PTT crystal was calculated from its bond polarizabilities to be 0.029. This Δn is almost an order of magnitude smaller than poly(ethylene terephthalate)'s value at 0.22, although both polymers have nearly identical crystal refractive indices. The small Δn is due to the arrangement of PTT's methylene groups in gauche conformations, causing the chain‐repeating unit to be tilted ∼53° away from the c axis toward the basal plane. Because of the small Δn, the crystalline‐phase orientation made only a small contribution to the overall birefringence despite the fiber's high crystallinity and orientation. To understand the effect of the number of methylene groups on polyester optical anisotropy, the Δn's of a series of poly(m‐alkylene terephthalates) with m = 2–5 were compared and correlated with ψ: an angle made by the normal of the benzene ring with the crystal's axis. As ψ′ decreases, Δn of the polyesters diminishes. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1513–1520, 2002
Linear versus nonlinear determinations of equilibrium melting temperatures of poly(trimethylene terephthalate) and miscible blend with poly(ether imide) exhibiting multiple melting peaks
Authors: Wu Pi‐Ling , Woo E. M. 
Published: October 2002

AbstractMultiple melting peaks in some semicrystalline polymers such as poly(trimethylene terephthalate) (PTT) have caused some difficulty in estimating accurately the equilibrium melting points. PTT forms a miscible blend with amorphous poly(ether imide) (PEI); for comparison purposes, a miscible system of a fixed composition (PTT/PEI of weight ratio = 9/1) was determined. PTT and its miscible blend both exhibited dual melting peaks (labeled as low and high peaks: Tm,L, Tm,H), and the first peaks (Tm,L), not the second peak (Tm,H), should be used for extrapolation. The equilibrium melting temperatures (T) of neat PTT and its blend PTT/PEI (9/1) were 245.2 and 242.4 °C, respectively, by the linear Hoffman–Weeks treatment using the corrected values of Tm,L (i.e., values obtained using a heating rate close to zero). Linear and nonlinear treatments led to a significant difference in estimated T, and the relative validity of these two methods is discussed. The nonlinear estimate yielded a higher value by about 27.3 °C for neat PTT and 23.1 °C for the PTT/PEI (9/1) blend, respectively (also the correction in Tm,L at the same condition mentioned previously). Results showed melting depression in miscible PTT/PEI (9/1). In addition, the T value of neat PTT was higher than that of PTT/PEI (9/1) owing to much thicker and more‐perfect crystals in neat PTT. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1571–1581, 2002
Effect of the interfacial interaction on the phase structure and rheological behavior of polypropylene/ethylene– octene copolymer/BaSO4 ternary composites
Authors: Li Zhen , Guo Shaoyun , Song Wentao , Yan Yan 
Published: October 2002

AbstractIn polypropylene (PP)/ethylene–octene copolymer (POE)/BaSO4 ternary composites, two different kinds of phase structures are assumed:(1) POE and BaSO4 filler are separately dispersed in the PP matrix and (2) POE‐encapsulated filler particles (core–shell structure) are dispersed in the matrix. This depends on the interfacial interaction of the composites. For the design of composites with different interfacial interactions, three routes for the preparation of BaSO4 master batches were developed. First, a mixture of BaSO4, POE, and maleic anhydride (MAH) in a certain ratio was extruded in the presence of dicumyl peroxide and then pelletized. In extrusion, MAH‐functionalized POE was in situ formed to enhance the interfacial interaction between POE and BaSO4. Second, a mixture of POE and BaSO4 was directly extruded and then pelletized. Third, after BaSO4 was treated with an organic titanate coupling agent, the treated BaSO4 and POE were blended in extrusion and then pelletized. Scanning electron microscopy observations showed that the core–shell structure in which POE encapsulates BaSO4 particles is formed through route 1, whereas POE and BaSO4 are separately dispersed into the PP matrix through routes 2 and 3. The rheological behavior of PP/POE/BaSO4 ternary composites was studied with a controlled stress rheometer. The results showed that the interfacial interaction in composites with core–shell morphology is the strongest. Interparticle interactions give rise to the formation of interparticle networks; the stronger the network is, the larger the shear yield stress is and the smaller the thixotropic loop area is. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1804–1812, 2002
Affected self‐respect and self‐value: the impact of breast cancer treatment on self‐esteem and QoL
Authors: Berterö Carina M. 
Published: October 2002

AbstractThere is a need to understand and explain the impact of breast cancer on women's self‐esteem and quality of life. The purpose of the present study was to identify and describe, from the perspective of the women's lived experiences, the impact of breast cancer on women's self‐esteem and elucidate its impact on their quality of life. Thirteen women diagnosed as having breast cancer were interviewed about these phenomena. The narrated interviews, tape‐recorded and transcribed verbatim were analysed and interpreted using a qualitative text analysis, based on the following question: What sense of satisfaction and importance is there with respect to the women's value and preferences? The findings were interpreted as affected self‐respect and self‐value, which were found to be important aspects affecting the quality of life of these women, within this lies the satisfaction of desire, to be respected and loved as the women they are. Concerns related to their quality of life seemed to be heightened when treatment has been completed, i.e. when the psychological effects of the treatment experience become a reality. Health professional need to be aware of how to recognise these women, in order to provide them with support to maintain a positive self‐esteem to enhance quality of life as a caring outcome. Copyright © 2002 John Wiley & Sons, Ltd.
Factors that influence adherence to exercise and their effectiveness: Application to cystic fibrosis
Authors: Prasad S.A. , Cerny F.J. 
Published: October 2002

AbstractAppropriate, regular exercise is of benefit to patients with cystic fibrosis (CF). As with other segments of the population, it has been difficult to devise exercise programs to which most patients will adhere for long periods of time. In healthy children, factors that are related to positive exercise compliance include social support, perceptions of competency and self‐esteem, enjoyment of activity, and availability of a variety of activities. In patients with CF, complications associated with the disease, e.g., time required for other treatment and fatigue, make compliance with recommended exercise activities more difficult. Factors likely to increase compliance in this population include explicit and continued encouragement and support from the family and healthcare team, and the introduction of behavior‐changing strategies. Pediatr Pulmonol. 2002; 34:66–72. © 2002 Wiley‐Liss, Inc.
Altered apoptotic gene expression and acquired apoptotic resistance in cadmium‐transformed human prostate epithelial cells
Authors: Achanzar William E. , Webber Mukta M. , Waalkes Michael P. 
Published: October 2002

AbstractBACKGROUNDCadmium is a suspected prostatic carcinogen, although the underlying mechanisms are unclear. To investigate these mechanisms, we performed molecular comparisons between the cadmium‐transformed prostate epithelial cell line CTPE and the nontumorigenic parental line RWPE‐1.METHODSGene expression patterns were compared by using cDNA arrays, RNase protection assays, and Western blots. Apoptosis was analyzed by using flow cytometry to quantify apoptotic nuclei and an enzyme‐linked immunosorbent assay method to measure DNA fragmentation. Caspase‐3 activity was measured colorimetrically.RESULTSAmong the genes down‐regulated in CTPE cells were those encoding several members of the caspase family of apoptotic proteases as well as the apoptotic regulator Bax. Ribonuclease protection assays confirmed global down‐regulation of caspase gene expression in CTPE. Decreased Bax expression in CTPE was confirmed by Western blots, which also revealed increased expression of anti‐apoptotic Bcl‐2. Consistent with these changes, CTPE cells exhibited increased resistance to apoptosis induced by cadmium, cisplatin, and etoposide. CTPE cells also exhibited lower caspase‐3 activity vs. RWPE‐1 after etoposide treatment.CONCLUSIONSCTPE cells exhibited altered expression of important apoptotic regulators as well as resistance to several apoptotic stimuli. We hypothesize that acquired apoptotic resistance may be a key aspect of cadmium‐induced malignant transformation of prostate epithelial cells and that this may contribute to both tumor initiation and the acquisition of aggressive characteristics subsequent to tumor formation. Prostate 52:236–244, 2002. © 2002 Wiley‐Liss, Inc.
Postatrophic hyperplasia of the prostate in Japan: Histologic and immunohistochemical features and p53 gene mutation analysis
Authors: Tsujimoto Yuichi , Takayama Hitoshi , Nonomura Norio , Okuyama Akihiko , Aozasa Katsuyuki 
Published: October 2002

AbstractBACKGROUNDPostatrophic hyperplasia (PAH) is one of the patterns of prostatic atrophy but has been regarded as a precursor of prostatic cancer (PCA) because of its possible increase in proliferative activity compared with simple atrophy and morphologic mimicry of PCA.METHODSRadical prostatectomy specimens obtained from 28 patients with PCA were analyzed by histologic and immunohistochemical methods by using 34βE12 and Ki‐67 as primary antibodies. Tissue from PAH, PCA, high‐grade prostatic intraepithelial neoplasia (HGPIN), a possible precursor of PCA, and benign hyperplasia were microdissected and p53 gene mutations were examined by the polymerase chain reaction–single strand conformation polymorphism method followed by direct sequencing.RESULTSHistologically, PAH consists of compactly arranged small acini with irregular atrophic‐appearing contours, mimicking PCA. PAH lesions were detected in 7 (25%) of 28 cases with PCA: multifocal in 6 of 7 (85.7%) cases, maximum size of lesions ranged from 0.3 to 2.3 mm. Mild nuclear enlargement and small nucleoli were observed in all cases. Capsular or perineural invasion, crystalloids, and mitotic figures were not found in any case. Inflammatory changes and fibrosis near PAH were found in 100% and 71% of cases, respectively. PAH involved non‐transition zone in all cases and occasionally involved transition zone. Forty‐three percent of PAH lesions were in proximity (<2 mm) to PCA. None of the clinical and pathologic factors examined were correlated with the presence of PAH. Immunohistochemical analysis by using 34βE12 revealed intact basal cells. Proliferative activity defined by positive rate for labeling with MIB‐1 antibody was intermediate between benign prostatic hyperplasia and HGPIN. The frequency of p53 mutations in PAH lesions was 5.3%, which was similar to that in HGPIN lesions (4.2%). Benign glands never showed mutations.CONCLUSIONThese findings suggested that PAH might be a precursor for PCA. Prostate 52: 279–287, 2002. © 2002 Wiley‐Liss, Inc.
Performance evaluation of a new algorithm for the detection of remote homologs with sequence comparison
Authors: Kann Maricel G. , Goldstein Richard A. 
Published: October 2002

AbstractA detailed analysis of the performance of hybrid, a new sequence alignment algorithm developed by Yu and coworkers that combines Smith Waterman local dynamic programming with a local version of the maximum‐likelihood approach, was made to access the applicability of this algorithm to the detection of distant homologs by sequence comparison. We analyzed the statistics of hybrid with a set of nonhomologous protein sequences from the SCOP database and found that the statistics of the scores from hybrid algorithm follows an Extreme Value Distribution with lambda ∼1, as previously shown by Yu et al. for the case of artificially generated sequences. Local dynamic programming was compared to the hybrid algorithm by using two different test data sets of distant homologs from the PFAM and COGs protein sequence databases. The studies were made with several score functions in current use including OPTIMA, a new score function originally developed to detect remote homologs with the Smith Waterman algorithm. We found OPTIMA to be the best score function for both both dynamic programming and the hybrid algorithms. The ability of dynamic programming to discriminate between homologs and nonhomologs in the two sets of distantly related sequences is slightly better than that of hybrid algorithm. The advantage of producing accurate score statistics with only a few simulations may overcome the small differences in performance and make this new algorithm suitable for detection of homologs in conjunction with a wide range of score functions and gap penalties. Proteins 2002;48:367–376. © 2002 Wiley‐Liss, Inc.
Optimization of a new score function for the generation of accurate alignments
Authors: Qian Bin , Goldstein Richard A. 
Published: October 2002

AbstractThe accuracy of the alignments of protein sequences depends on the score matrix and gap penalties used in performing the alignment. Most score functions are designed to find homologs in the various databases rather than to generate accurate alignments between known homologs. We describe the optimization of a score function for the purpose of generating accurate alignments, as evaluated by using a coordinate root‐mean‐square deviation (RMSD)‐based merit function. We show that the resulting score matrix, which we call STROMA, generates more accurate alignments than other commonly used score matrices, and this difference is not due to differences in the gap penalties. In fact, in contrast to most of the other matrices, the alignment accuracies with STROMA are relatively insensitive to the choice of gap penalty parameters. Proteins 2002;48:605–610. © 2002 Wiley‐Liss, Inc.
A novel fold recognition method using composite predicted secondary structures
Authors: An Yuling , Friesner Richard A. 
Published: October 2002

AbstractIn this work, we introduce a new method for fold recognition using composite secondary structures assembled from different secondary structure prediction servers for a given target sequence. An automatic, complete, and robust way of finding all possible combinations of predicted secondary structure segments (SSS) for the target sequence and clustering them into a few flexible clusters, each containing patterns with the same number of SSS, is developed. This program then takes two steps in choosing plausible homologues: (i) a SSS‐based alignment excludes impossible templates whose SSS patterns are very different from any of those of the target; (ii) a residue‐based alignment selects good structural templates based on sequence similarity and secondary structure similarity between the target and only those templates left in the first stage. The secondary structure of each residue in the target is selected from one of the predictions to find the best match with the template. Truncation is applied to a target where different predictions vary. In most cases, a target is also divided into N‐terminal and C‐terminal fragments, each of which is used as a separate subsequence. Our program was tested on the fold recognition targets from CASP3 with known PDB codes and some available targets from CASP4. The results are compared with a structural homologue list for each target produced by the CE program (Shindyalov and Bourne, Protein Eng 1998;11:739–747). The program successfully locates homologues with high Z‐score and low root‐mean‐score deviation within the top 30–50 predictions in the overwhelming majority of cases. Proteins 2002;48:352–366. © 2002 Wiley‐Liss, Inc.
Physicochemical explanation of peptide binding to HLA‐A*0201 major histocompatibility complex: A three‐dimensional quantitative structure‐activity relationship study
Authors: Doytchinova Irini A. , Flower Darren R. 
Published: October 2002

AbstractA three‐dimensional quantitative structure‐activity relationship method for the prediction of peptide binding affinities to the MHC class I molecule HLA‐A*0201 was developed by applying the CoMSIA technique on a set of 266 peptides. To increase the self consistency of the initial CoMSIA model, the poorly predicted peptides were excluded from the training set in a stepwise manner and then included in the study as a test set. The final model, based on 236 peptides and considering the steric, electrostatic, hydrophobic, hydrogen bond donor, and hydrogen bond acceptor fields, had q2 = 0.683 and r2 = 0.891. The stability of this model was proven by cross‐validations in two and five groups and by a bootstrap analysis of the non‐cross‐validated model. The residuals between the experimental pIC50 (‐logIC50) values and those calculated by “leave‐one‐out” cross‐validation were analyzed. According to the best model, 63.2% of the peptides were predicted with |residuals| ≤ 0.5 log unit; 29.3% with 1.0 ≤ |residuals| < 0.5; and 7.5% with |residuals| > 1.0 log unit. The mean |residual| value was 0.489. The coefficient contour maps identify the physicochemical property requirements at each position in the peptide molecule and suggest amino acid sequences for high‐affinity binding to the HLA‐A*0201 molecule. Proteins 2002;48:505–518. © 2002 Wiley‐Liss, Inc.