bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of calcium stearate addition of ultrahigh molecular weight polyethylene in direct compression molding
Authors: Utsumi Masahiro , Nagata Kazuya , Suzuki Masahiko , Mori Akiko , Sakuramoto Itsuo , Torigoe Yuuichi , Kaneeda Toshiaki , Moriya Hideshige 
Published: January 2003

AbstractThe effects of calcium stearate addition in molding of ultrahigh molecular weight polyethylene (UHMWPE) were investigated by tensile testing, scanning electron microscope (SEM), Fourier transform infrared (FT‐IR) spectroscopy, and elemental analysis. Four types of UHMWPE specimens with varying contents of calcium stearate (<5, 50, 100, and 1000 ppm) were used in this study. SEM observation revealed that calcium stearate added specimens have smoother and more homogeneous microstructures. After accelerated aging, subsurface oxidative degeneration was observed in all specimens; however, calcium stearate added specimens had less oxidative degeneration in comparison with specimens without additives. Specimens showed better mechanical properties with increasing content of calcium stearate. Though all specimens aggravated their mechanical properties due to oxidation after accelerated aging, the specimens of 100 ppm of calcium stearate showed better properties at 3.7 MPa larger yield strength and four times larger value of elongation at fracture than the specimens without additives. These results indicate that calcium stearate addition produces dense packing of UHMWPE particles, which brings about stronger fusion among the particles and fewer structural defects, and results in better mechanical properties and better resistance to oxidative degeneration. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1602–1609, 2003
Sorption of chromium oxy‐anions onto cationized ligno‐cellulosic material
Authors: Zghida Haïfa , Baouab Mohamed Hassen V , Gauthier Robert 
Published: January 2003

AbstractQuaternary ammonium groups were grafted onto ligno‐cellulosic material (cotton, wood sawdust, and maize‐cob flour) to obtain a support able to adsorb oxy‐anions containing chromium atoms (chromate and dichromate). For both anions in aqueous solutions, adsorption proceeded very quickly and reached a limit value dependent on the rate of ammonium grafting; at saturation, the Cr/N+ ratio was always close to 1/1 for chromate anions, but two ammonium sites were needed to link a dichromate anion in a stable structure, resulting in the same 1/1 Cr/N+ ratio. Tentatives for modeling the adsorption process were performed with the Langmuir, Freundlich, and Jossen equations. A nearly total desorption occurred only when these saturated supports were treated with solutions of high ionic strength (4M potassium chloride). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1660–1665, 2003
Poly(L‐lactide). X. Enhanced surface hydrophilicity and chain‐scission mechanisms of poly(L‐lactide) film in enzymatic, alkaline, and phosphate‐buffered solutions
Authors: Tsuji Hideto , Ishida Takuya 
Published: January 2003

AbstractAttempts were carried out to enhance the surface hydrophilicity of poly(L‐lactide), that is, poly(L‐lactic acid) (PLLA) film, utilizing enzymatic, alkaline, and autocatalytic hydrolyses in a proteinase K/Tris–HCL buffered solution system (37°C), in a 0.01N NaOH solution (37°C), and in a phosphate‐buffered solution (100°C), respectively. Moreover, its chain‐scission mechanisms in these different media were studied. The advancing contact‐angle (θa) value of the amorphous‐made PLLA film decreased monotonically with the hydrolysis time from 100° to 75° and 80° without a significant molecular weight decrease, when enzymatic and alkaline hydrolyses were continued for 60 min and 8 h, respectively. In contrast, a negligible change in the θa value was observed for the PLLA films even after the autocatalytic hydrolysis was continured for 16 h, when their bulk Mn decreased from 1.2 × 105 to 2.2 × 104 g mol−1 or the number of hydrophilic terminal groups per unit weight increased from 1.7 × 10−5 to 9.1 × 10−5 mol g−1. These findings, together with the result of gravimetry, revealed that the enzymatic and alkaline hydrolyses are powerful enough to enhance the practical surface hydrophilicity of the PLLA films because of their surface‐erosion mechanisms and that its practical surface hydrophilicity is controllable by varying the hydrolysis time. Moreover, autocatalytic hydrolysis is inappropriate to enhance the surface hydrophilicity, because of its bulk‐erosion mechanism. Alkaline hydrolysis is the best to enhance the hydrophilicity of the PLLA films without hydrolysis of the film cores, while the enzymatic hydrolysis is appropriate and inappropriate to enhance the surface hydrophilicity of bulky and thin PLLA materials, respectively, because a significant weight loss occurs before saturation of θa value. The changes in the weight loss and θa values during hydrolysis showed that exo chain scission as well as endo chain scission occurs in the presence of proteinase K, while in the alkaline and phosphate‐buffered solutions, hydrolysis proceeds via endo chain scission. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1628–1633, 2003
Photoluminescence and excimer emission of functional groups in light‐emitting polymers
Authors: Fehervari Agota F. , Kagumba Lawino C. , Hadjikyriacou Savvas , Chen Freeman , Gaudiana Russell A. 
Published: January 2003

AbstractNear‐UV and blue‐light‐emitting polymers were synthesized with luminescent functional groups in the side chains or in the polymer main chain. The unsubstituted fluorophores, 2,5‐diphenylfuran, 2‐phenylbenzoxazole, and triphenylamine, do not form excimers in solution; however, in the case of polymers, excimer emission was negligible only with 2‐phenylbenzoxazole derivatives. The monomers as well as the polymers, poly(2‐(4‐vinylphenyl)‐benzoxazole), poly{N‐(4‐benzoxazol‐2‐yl‐phenyl)‐N′‐[2‐(methacryloyloxy)ethyl]urea}, and the polyurea of 2‐(4‐aminophenyl)‐5‐aminobenzoxazole with 1,5‐diisocyanato‐2‐methylpentane, were strong blue emitters; photoluminescence shifted to longer wavelengths than that of 2‐phenylbenzoxazole. Light‐emitting polymers containing 2,5‐diphenylfuran derivatives, including poly[2‐(4‐vinylphenyl)‐5‐phenylfuran], poly[2‐(4‐vinylphenyl)‐5‐(4‐tert‐butylphenyl)furan], and poly(N‐[2‐(methacryloyloxy)ethyl]‐N′‐{4‐[5‐(4‐tert‐butylphenyl)‐2‐furyl]phenyl}urea), particularly in solid films, exhibited a strong blue excimer emission. The emission characteristics of polymers with triphenylamine side chains were influenced by the mode of attachment of the luminescent group. A longer spacer group between the lumophore and the polymer main chain successfully minimized excimer emission in poly{N‐[2‐(methacryloyloxy)ethyl]‐N′‐[4‐(N,N‐diphenylamino)phenyl]urea}, showing near UV/violet photoluminescence. Polymers with a shorter connecting group, such as poly[4‐(N,N‐diphenylamino)benzyl acrylate], displayed blue excimer emission. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1634–1645, 2003
Monodisperse nanoparticles of poly(ethylene glycol) macromers and N‐isopropyl acrylamide for biomedical applications
Authors: Leobandung William , Ichikawa Hideki , Fukumori Yoshinobu , Peppas Nicholas A. 
Published: January 2003

AbstractPoly(ethylene glycol)‐based nanoparticles have received significant attention in the field of biomedicine. When they are copolymerized with pH‐ or temperature‐sensitive comonomers, their small size allows them to respond very quickly to changes in the environment, including changes in the pH, ionic strength, and temperature. In addition, the high surface‐to‐volume ratio makes them highly functionalized. In this work, nanoparticles composed of temperature‐sensitive poly(N‐isopropylacrylamide), poly(ethylene glycol) 400 dimethacrylate, and poly(ethylene glycol) 1000 methacrylate were prepared by a thermally initiated, free‐radical dispersion polymerization method. The temperature‐responsive behavior of the hydrogel nanoparticles was characterized by the study of their particle size with photon correlation spectroscopy. The size of the nanoparticles varied from 200 to 1100 nm and was a strong function of the temperature of the system, from 5 to 40°C. The thermal, structural, and morphological characteristics were also investigated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1678–1684, 2003
Natural and artificial aging of polypropylene–polyethylene copolymers
Authors: Colom X. , Cañavate J. , Suñol J. J. , Pagès P. , Saurina J. , Carrasco F. 
Published: January 2003

AbstractThe degradation of polypropylene–polyethylene copolymers (which were used to make the seats for the Olympic stadium in Barcelona, Spain), in response to natural aging for 2.5 years and artificial aging for 5000 h in a xenon lamp chamber, was studied. The extent of the various photoreactions, including the formation of carbonyl groups, the scission of hydrocarbonated chains, the formation of free radicals in tertiary carbons, and the formation of nonsaturated bonds followed by branching and crosslinking, was analyzed by Fourier transform infrared spectrophotometry. Melting and thermal decomposition were studied by differential scanning calorimetry. In all cases, aging led to a loss of crystallinity. By scanning electron microscopy, it was possible to detect the formation of a porous material after melting crystallization, as well as the presence of micelle orientation. Finally, a comparison between natural and artificial aging effects showed differences, the samples exposed to weathering being modified to a greater extent than the artificially aged ones. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1685–1692, 2003
Synthesis and characterization of nylon 6/polyalkylaniline conducting composites
Authors: Sarı Bekir , Talu Muzaffer , Gök Ayşegül 
Published: January 2003

AbstractConducting composite films of polyalkylanilines with nylon 6 as the insulating matrix were electrochemically synthesized and characterized. The electrochemical properties of the alkylanilines and their composites were investigated with a cyclic voltammetry technique. The magnetic properties of the polymers and composites were analyzed, and their conducting mechanisms were found to be of bipolaron nature. With Fourier transform infrared spectra, it was clarified that polymerization occurred via the NH2 group in a head‐to‐tail mechanism. Through thermogravimetric analyses, the thermal properties of the polymers and their composites were elucidated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1693–1701, 2003
Impact modified isotatic polypropylene with controlled rubber intrinsic viscosities: Some new aspects about morphology and fracture
Authors: Grein C. , Bernreitner K. , Hauer A. , Gahleitner M. , Neißl W. 
Published: January 2003

AbstractThe influence of the molecular weight of the dispersed phase of ethylene–propylene rubber modified isotactic polypropylene (iPP/EPR) reactor blends was studied in a systematic way by varying their intrinsic viscosity (IV) from 1.7 to 6 dg/L while keeping the matrix melt flow rate (MFR) constant. Standard Charpy measurements were completed by a continuous analysis of the impact properties over a wide range of temperatures at fixed test speed. As expected, the higher the IV, the tougher the iPP/EPR blends. However, ductile–brittle transitions as key mechanical descriptors did not correlate linearly with Mw, suggesting the macroscopic behavior of the blend to be controlled primarily by the morphology of the EPR particles. Moreover, strong correlations were found between impact mechanical properties, amount of stress‐whitening, and strength of the molecular relaxations estimated from dynamical mechanical analysis. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1702–1712, 2003
Experimental studies on extrudate swell behavior of PS and LLDPE melts in single and dual capillary dies
Authors: Sombatsompop N. , O‐Charoen N. 
Published: January 2003

AbstractExtrudate swell behavior of polystyrene (PS) and linear low‐density polyethylene (LLDPE) melts was investigated using a constant shear rate capillary rheometer. Two capillary dies with different design configurations were used, one being a single flow channel and the other being a dual flow channel. A number of extrudate swell related parameters were examined, and used to explain the discrepancies in the extrudate swell results obtained from the single and dual flow channel dies, the parameters including output rate and output rate ratio, power law index, wall shear rate, wall shear stress, melt residence time, pressure drop induced temperature rise, flow channel position relative to the barrel centerline, and the flow patterns. It was found in this work that the power law index (n value) was the main parameter to determine the output rate ratio and the extrudate swell between the large and small holes for the dual flow channel die: the greater the n value the lower the output rate ratio and thus decreased extrudate swell ratio. The differences in the extrudate swell ratio and flow properties for PS and LLDPE melts resulted from the output rate ratio and the molecular chain structure, respectively. The extrudate swell was observed to increase with wall shear rate. The discrepancies in the extrudate swell results from single and dual dies for a given shear rate were caused by differences in the flow patterns in the barrel and die, and the change in the melt velocities flowing from the barrel and in the die to the die exit. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1713–1722, 2003
Using the user's mental model to guide the integration of information space into information need
Authors: Cole Charles , Leide John E. 
Published: January 2003

AbstractThe study reported here tested the efficacy of an information retrieval system output summary and visualization scheme for undergraduates taking a Vietnam War history who were in Kuhlthau's Stage 3 of researching a history essay. The visualization scheme consisted of (a) the undergraduate's own visualization of his or her essay topic, drawn by the student on the bottom half of a sheet of paper, and (b) a visualization of the information space (determined by index term counting) on the top‐half of the same page. To test the visualization scheme, students enrolled in a Vietnam War history course were randomly assigned to either the visualization scheme group, who received a high recall search output, or the nonvisualization group, who received a high precision search output. The dependent variable was the mark awarded the essay by the course instructor. There was no significant difference between the mean marks for the two groups. We were pleasantly surprised with this result given the bad reputation of high recall as a practical search strategy. We hypothesize that a more pro‐active visualization system is needed that takes the student through the process of using the visualization scheme, including steps that induce student cognition about task–subject objectives.
Browsing‐based conceptual information retrieval incorporating dictionary term relations, keyword association, and a user's interest
Authors: Nakashima Makoto , Sato Keizo , Qu Yanhua , Ito Tetsuro 
Published: January 2003

AbstractA model of browsing‐based conceptual information retrieval is proposed employing two different types of dictionaries, a global dictionary and a local dictionary. A global dictionary with the authorized terms is utilized to capture the commonly acknowledgeable conceptual relation between a query and a document by replacing their keywords with the dictionary terms. The documents are ranked by the conceptual closeness to a query, and are arranged in the form of a user's personal digital library, or pDL. In a pDL a user can browse the arranged documents based on a suggestion about which documents are worth examining. This suggestion is made by the information in a local dictionary that is organized so as to reflect a user's interest and the association of keywords with the documents. Experiments for testing the retrieval performance of utilizing the two types of dictionaries were also performed using standard test collections.
Matchsimile: A flexible approximate matching tool for searching proper names
Authors: Navarro Gonzalo , Baeza‐Yates Ricardo , Marcelo Azevedo Arcoverde João 
Published: January 2003

AbstractWe present the architecture and algorithms behind Matchsimile, an approximate string matching lookup tool especially designed for extracting person and company names from large texts. Part of a larger information extraction environment, this specific engine receives a large set of proper names to search for, a text to search, and search options; and outputs all the occurrences of the names found in the text. Beyond the similarity search capabilities applied at the intraword level, the tool considers a set of specific person name formation rules at the word level, such as combination, abbreviation, duplicity detections, ordering, word omission and insertion, among others. This engine is used in a successful commercial application (also named Matchsimile), which allows searching for lawyer names in official law publications.
Scholarly use of the Web: What are the key inducers of links to journal Web sites?
Authors: Vaughan Liwen , Thelwall Mike 
Published: January 2003

AbstractWeb links have been studied by information scientists for at least six years but it is only in the past two that clear evidence has emerged to show that counts of links to scholarly Web spaces (universities and departments) can correlate significantly with research measures, giving some credence to their use for the investigation of scholarly communication. This paper reports on a study to investigate the factors that influence the creation of links to journal Web sites. An empirical approach is used: collecting data and testing for significant patterns. The specific questions addressed are whether site age and site content are inducers of links to a journal's Web site as measured by the ratio of link counts to Journal Impact Factors, two variables previously discovered to be related. A new methodology for data collection is also introduced that uses the Internet Archive to obtain an earliest known creation date for Web sites. The results show that both site age and site content are significant factors for the disciplines studied: library and information science, and law. Comparisons between the two fields also show disciplinary differences in Web site characteristics. Scholars and publishers should be particularly aware that richer content on a journal's Web site tends to generate links and thus the traffic to the site.
Empirical evidence of self‐organization?
Authors: van den Besselaar Peter 
Published: January 2003

AbstractIn a recent paper in this journal, Loet Leydesdorff and Gaston Heimeriks (2001, Journal of the American Society for Information Science and Technology, 52, 1262–1294.) argue that biotechnology develops in a self‐organizational mode, through interaction between the intellectual structure and the institutional network of the research field. This claim is empirically supported by a multivariate analysis of documents from core biotechnology journals. One unexpected finding in this paper is the relationship between the title words of documents and the region of their origin. This claim requires examination because, as will be shown, it seems to be an artifact of the method used. If this is so, it undermines the authors' theoretical claim that the production of knowledge is a self‐organizing process.
Does matching up features mess up job choice? Boundary conditions on attribute‐salience effects
Authors: Slaughter Jerel E. , Highhouse Scott 
Published: January 2003

AbstractResearch in decision making has suggested that the degree to which features of an option are shared versus unique influences preferences in a way that violates normative rules. The generalizability of these findings to job choice was investigated. Senior‐level, undergraduate job seekers (N = 216) were presented with three jobs from which they were asked to choose one. Attributes for two of the jobs (A and B) remained invariant across conditions, and attributes for a third job (C) were manipulated such that it shared unfavorable features with one of the invariant jobs (A or B) and favorable attributes with the other job (B or A). Results suggested that jobs with unique positive features and shared negative features were preferred over those with unique negative features and shared positive features only when information was presented in a simple (versus complex) format and when participants did not rate the importance of attributes prior to the choice task. We suggest that inferences from feature‐matching research should be qualified by these boundary conditions. Copyright © 2002 John Wiley & Sons, Ltd.
Multiple mediators of plant programmed cell death: Interplay of conserved cell death mechanisms and plant‐specific regulators
Authors: Hoeberichts Frank A. , Woltering Ernst J. 
Published: January 2003

AbstractProgrammed cell death (PCD) is a process aimed at the removal of redundant, misplaced, or damaged cells and it is essential to the development and maintenance of multicellular organisms. In contrast to the relatively well‐described cell death pathway in animals, often referred to as apoptosis, mechanisms and regulation of plant PCD are still ill‐defined. Several morphological and biochemical similarities between apoptosis and plant PCD have been described, including DNA laddering, caspase‐like proteolytic activity, and cytochrome c release from mitochondria. Reactive oxygen species (ROS) have emerged as important signals in the activation of plant PCD. In addition, several plant hormones may exert their respective effects on plant PCD through the regulation of ROS accumulation. The possible plant PCD regulators discussed in this review are integrated in a model that combines plant‐specific regulators with mechanisms functionally conserved between animals and plants. BioEssays 25:47–57, 2003. © 2002 Wiley Periodicals, Inc.
Making use of the primary tumour
Authors: Baars Arnold , Buter Jan , Pinedo Herbert M. 
Published: January 2003

AbstractSurgical resection of a primary tumour is often not sufficient to cure a patient. Even when no residual cancer can be detected at time of surgery, metastases may appear in the following years, which indicates that the primary tumour had apparently spread before surgery. Following surgery, systemic chemotherapy may be used to eradicate micro‐metastatic disease. Here we present two unconventional strategies that implement new insights into tumour biology and tumour immunology in the treatment of patients with cancer. Both experimental strategies use the individual characteristics of the patient's primary tumour to optimise the control of life‐threatening micro‐metastases. We aim to modulate the patient's adaptive immune system, targeting it towards the patient's own tumour cells to eradicate residual disease following local treatment. In one approach, this is done by autologous tumour cell vaccinations as adjuvant treatment for colon cancer patients and, in a second approach, by giving chemo‐imunotherapy before local treatment to women with locally advanced breast cancer. BioEssays 25:79–86, 2003. © 2002 Wiley Periodicals, Inc.
Constitutive cycling: A general mechanism to regulate cell surface proteins
Authors: Royle Stephen J. , Murrell‐Lagnado Ruth D. 
Published: January 2003

AbstractCells can change their function by rapidly modulating the levels of certain proteins at the plasma membrane. This rapid modulation is achieved by using a specialised trafficking process called constitutive cycling. The constitutive cycling of a variety of transmembrane proteins such as receptors, channels and transporters has recently been directly demonstrated in a wide range of cell types. This regulation is thought to underlie important biological phenomena such as learning and memory, gastric acid secretion and water and blood glucose homeostasis. This review discusses the molecular mechanisms of constitutive cycling, its regulation by extracellular agents such as hormones and its misregulation in disease states. BioEssays 25:39–46, 2003. © 2002 Wiley Periodicals, Inc.