bluuebunny/crossref_metadata_2025_split huggingface dataset:
Myocardial sympathetic degeneration correlates with clinical phenotype of Parkinson's disease
Authors: Spiegel Jörg , Hellwig Dirk , Farmakis Georgios , Jost Wolfgang H. , Samnick Samuel , Fassbender Klaus , Kirsch Carl‐Martin , Dillmann Ulrich 
Published: April 2007

AbstractIn idiopathic Parkinson's disease (PD), different clinical subtypes are distinguished due to predominant motor symptoms: a tremor‐dominant type (TDT), an akinetic rigid type (ART), and a mixed type (MT). We compared myocardial sympathetic innervation, measured by MIBG scintigraphy, in different subtypes of PD at early and advanced stages of PD. We applied MIBG scintigraphy in 102 patients with PD. About 57 patients were at Hoehn and Yahr (H&Y) stage 1, 22 at H&Y stage 2, and 23 at H&Y stages 3 and 4. For quantification of myocardial MIBG uptake, the heart‐to‐mediastinum (H/M) count‐ratio was calculated. At all H&Y stages, myocardial MIBG uptake was significantly higher in TDT patients than in ART or MT patients (P < 0.05; ANOVA). Furthermore, at each H&Y stage, myocardial MIBG uptake correlated significantly with severity of hypokinesia (P < 0.05; Spearman's correlation) and rigidity (P < 0.05), but not with severity of resting or postural tremor. The significant correlation between myocardial sympathetic degeneration and severity of hypokinesia and rigidity suggests that myocardial sympathetic degeneration and hypokinetic‐rigid symptoms develop in a closely coupled manner in early as well as advanced PD. No such correlation can be found between myocardial sympathetic degeneration and parkinsonian tremor. © 2007 Movement Disorder Society
Effect of coffee Melanoidin on human hepatoma HepG2 cells. Protection against oxidative stress induced by tert‐butylhydroperoxide
Authors: Goya Luis , Delgado‐Andrade Cristina , Rufián‐Henares José A. , Bravo Laura , Morales Francisco J. 
Published: April 2007

AbstractSoluble high‐molecular weight fraction (named melanoidin) from coffee brew was isolated by ultrafiltration, subsequently digested by simulating a gastric plus pancreatic digestive condition and partly characterized by CZE, gel‐filtration and browning. The objective of the present study was to investigate the potential protective effect of the coffee melanoidin submitted to gastrointestinal digestion on cell viability (lactate dehydrogenase leakage) and redox status of cultured human hepatoma HepG2 cells submitted to oxidative stress induced by tert‐butylhydroperoxide (t‐BOOH). Concentration of reduced glutathione (GSH) and malondialdehyde (MDA), generation of reactive oxygen species (ROS) and activity of antioxidant enzymes glutathione peroxidase (GPx) and reductase (GR) were used as markers of cellular oxidative status. Pretreatment of cultured HepG2 cells with 0.5–10 μg/mL digested coffee melanoidin (DCM) for 2 or 20 h completely prevented the increase in cell damage and GR and partly prevented the decrease of GSH and the increase of MDA and GPx evoked by t‐BOOH in HepG2 cells. In contrast, increased ROS generation induced by t‐BOOH was not prevented when cells were pretreated with DCM. The results show that treatment of HepG2 cells with concentrations of DCM within the expected physiological range confers the cells a significant protection against an oxidative insult.
Birth of cloned miniature pigs derived from somatic cell nuclear transferred embryos activated by ultrasound treatment
Authors: Miyoshi Kazuchika , Inoue Sumiko , Himaki Takehiro , Mikawa Satoshi , Yoshida Mitsutoshi 
Published: April 2007

AbstractThe present study was carried out to determine (1) the optimal duty cycle of ultrasound for activation of pig oocytes and cloned embryos derived from miniature pig fetal fibroblasts and (2) whether cloned embryos can develop to term following activation by ultrasound stimulation. When oocytes were exposed to ultrasound with 20% or 30% duty cycle, the blastocyst formation rates were significantly (P < 0.05) higher than that of oocytes exposed to ultrasound with 10% duty cycle. In contrast, the blastocyst formation rate of cloned embryos decreased as the duty cycle of ultrasound increased; the value of embryos exposed to ultrasound with 10% duty cycle was significantly (P < 0.05) higher than that of embryos exposed to ultrasound with 50% duty cycle. When cloned embryos exposed to ultrasound with 10% duty cycle were transferred into the oviducts of two recipient gilts to assess their development in vivo, the pregnancy of one of the gilts was maintained to term and two piglets were delivered via Cesarean section. The results of the present study showed that (1) although the duty cycle of ultrasound affects in vitro development after activation of both pig oocytes and miniature pig cloned embryos, the optimal duty cycle is different between them and (2) miniature pig cloned embryos have the ability to develop into piglets after activation by ultrasound stimulation. Mol. Reprod. Dev. 74: 1568–1574, 2007. © 2007 Wiley‐Liss, Inc.
Pathogenesis of apical periodontal cysts: guidelines for diagnosis in palaeopathology
Authors: Dias G. J. , Prasad K. , Santos A. L. 
Published: April 2007

AbstractApical periodontal cysts are benign lesions developing in relation to the apices of non‐vital teeth due to inflammatory response from the infective pulp. These are epithelium‐lined bony cavities containing fluid. Despite being widely reported in medical/dental literature, this common condition is poorly diagnosed and documented in the archaeological literature. We aim to clarify the correct terminology, demonstrate bony manifestations at different stages of pathogenesis of chronic periapical dental lesions into granuloma and apical periodontal cysts, and to describe diagnostic criteria which would provide practical guidelines for the diagnosis of these conditions.Three identified skulls from the International Exchange Collection, housed in the Anthropological Museum at the University of Coimbra, are used to identify the progression of this condition from a small periapical granuloma to a large apical periodontal cyst with expansion of alveolar and facial bones. The pathogenesis of this condition is described, together with its surgical management in the early 20th century in Portugal, which is the period in which these individuals lived. Confusion resulting from the different terminologies can be avoided if the term periapical granuloma is used to define apical bony lesions smaller than 3 mm at their maximum intra‐bony diameter, and the term apical periodontal cysts for the larger lesions. We recommend that these terminologies and parameters be used as a standard in future studies. This will make inter‐observer and inter‐population comparisons more accurate. Copyright © 2007 John Wiley & Sons, Ltd.
Polyisobutylene‐block‐polyoxyethylene‐block‐polyisobutylene as stabilizer in aqueous polymerization of styrene, methyl methacrylate, and vinyl acetate
Authors: Piirma Irja , Sar Bidulata 
Published: April 2007

AbstractAmphipathic triblock copolymers of polyisobutylene‐block‐polyoxy‐ethylene‐block‐polyisobutylene were synthesized by a coupling technique. Seven triblock copolymers were prepared by varying their hydrophobic and hydrophilic chain lengths. The stabilizing effectiveness of these polymeric surfactants was studied as a function of structural variations of the block copolymers in aqueous polymerizations of styrene, methyl methacrylate, and vinyl acetate.
Preparation and biochemical and biomedical applications of new monosized polymer particles
Authors: Ugelstad John , Mørk Preben C. , Schmid Ruth , Ellingsen Turid , Berge Arvid 
Published: April 2007

AbstractThe method for preparation of monodisperse polymer particles by activated swelling was first presented 12 years ago. Since then the principle of activated swelling has resulted in procedures for the production of a number of monodisperse systems with particle sizes and compositions that were unattainable by previous methods. It has also formed the basis for several new applications of polymer particles. A short review of the basic theoretical principles which have been used in the development of the new processes is given. Methods for preparation of monosized polymer particles are described, and the most important biochemical and biomedical applications of various types of particles, including magnetic particles, are given.
Crosslinking kinetics in emulsion polymerization
Authors: Tobita Hidetaka , Hamielec Archie E. 
Published: April 2007

AbstractNetwork formation in free‐radical polymerization is investigated both from experimental and theoretical points of view. In a bulk free‐radical crosslinking copolymerization, the radical concentration increases significantly due to a decrease in the bimolecular termination rate. Some fraction of radicals is trapped during the course of network formation, and the reactivity of the radicals in liquid state is completely different from that in solid state (trapped radicals) in terms of both propagation and termination.In emulsion crosslinking polymerization, the crosslinking density tends to be fairly high even from the start of the polymerization. The crosslinking density development is substantially different from that in bulk and solution polymerizations, in which the crosslinking density increases with time, at least in the earlier stages of polymerization. Due to the elastic contribution of free energy change, the monomer concentration in the polymer particles is lower than for linear emulsion polymerizations as long as the monomer droplets exist, resulting in an enhanced tendency toward crosslinking reactions.
Control of network structure in emulsion crosslinking copolymerization
Authors: Tobita Hidetaka , Hamielec Archie E. 
Published: April 2007

AbstractA kinetic model for network structure development during crosslinking copolymerization of vinyl and divinyl monomer is proposed. The model calculations suggest that polymer networks synthesized by free‐radical copolymerization are, in general, inhomogeneous at least on a microscopic scale. By application of the same kinetic parameters as those for bulk polymerizations, it was found that the crosslinking density of the polymers formed in the earlier stages of polymerization is very high in emulsion polymerizations and polymer networks tend to be highly heterogeneous. Homogeneous networks cannot be formed even under Flory's simplifying assumptions for vinyl/divinyl copolymerization in emulsion polymerizations. The present kinetic model can be used to find semi‐batch policies to control the network structure, and semi‐batch policies were used to illustrate the synthesis of homogeneous polymer networks.
Monodisperse ellipsoidal polystyrene latex particles: Preparation and characterisation
Authors: Ho C. C. , Ottewill R. H. , Keller A. , Odell J. A. 
Published: April 2007

AbstractAn improved version of a novel method first employed by Nagy & Keller for the preparation of monodisperse ellipsoidal polystyrene latex particles is described. The method involves embedding monodisperse spherical polystyrene latex particles as starting material in a deformable polymer matrix such as poly(vinyl alcohol) and deforming these mechanically to various predetermined macroscopic draw ratios to give ellipsoids of various axial ratios. Ellipsoids with lengths ranging from about 350 to 12250nm were prepared. Stable aqueous dispersions of these were recovered and characterised with respect to particle size and axial ratio distributions and surface morphology using electron microscopy. Axial ratios ranging from 2.0 to 5.65 were obtained for the resulting ellipsoids. Various factors influencing the monodispersity of the resulting ellipsoids in the preparation method are discussed.
Triboelectric charge control of polymer microspheres by surface modification using heterocoagulation
Authors: Shiozaki M. , Tokuno T. 
Published: April 2007

AbstractA new technique to control the triboelectric charge (TEC) of polymer microspheres is proposed. Polymer microspheres (PMs) were prepared by three‐component suspension copolymerization of styrene (S), 2‐ethylhexyl methacrylate (EHMA) and dimethylaminoethyl methacrylate (DM). Emulsion particles (EPs) for surface modification were prepared by emulsifier‐free three‐component emulsion copolymerization of S, EHMA and sodium styrene sulfonate (NaSS). PMs were covered with EPs by a process similar to the ‘stepwise heterocoagulation technique’ (Okubo, M., He, Y. & Ichikawa, K., Colloid Polym. Sci., 269 (1991) 125). The value of TEC of modified microspheres varied from ‐ 30 μC/g to ‐ 60 μC/g with increasing NaSS content of EPs from 3wt% to 6wt%, though unmodified particles had small values of TEC. This fact suggests that the surface modification used can lead to the preparation of particles having a desired TEC.
Dielectric spectroscopic characterization of a weak‐acid polystyrene colloid
Authors: Su Lao Sou , Jayasuriya Sunil , Fitch Robert M. 
Published: April 2007

AbstractA commercially available aqueous polystyrene colloid with surface ‐COOH groups was purified by exhaustive dialysis. This was then investigated for dielectric frequency response in the low frequency domain (0.01‐100 Hz), as a function of pH, ionic strength and the chemical nature of the counterions in the electrical double layer. In previous work on strong‐acid (sulfonate) colloids it had been shown that a plot of the imaginary part of the complex impedance as a function of the real part gave semicircles whose radii were a direct function of the surface charge density. In this work, surface charge is a function of pH. The degree of counterion binding was a function of hydrated ion size, as determined from an analysis of titration data and ionic strength of the continuous phase, which in turn was determined from the phase angle and the characteristic relaxation frequency. Dielectric spectroscopy is thus a powerful non‐invasive tool for quantitative analysis of the properties of the electrical double layer in these systems.
Fluorescence analysis for thermo‐sensitive hydrogel microspheres
Authors: Fujimoto K. , Nakajima Y. , Kashiwabara M. , Kawaguchi H. 
Published: April 2007

AbstractPoly(N‐isopropylacrylamide) (PNIPAM) hydrogel microspheres were prepared by precipitation polymerization above the polymer's lower critical solution temperature (LCST) in water. The hydrodynamic size of PNIPAM microspheres exhibited a thermo‐sensitive change around the LCST. In order to obtain information about the interface of the hydrogels, contact angle measurement, protein adsorption, and fluorescence analysis were performed. Contact angle measurement and protein adsorption showed a gradual change around the LCST similar to the change of the hydrodynamic size. However, fluorescence study exhibited a sharp change at the LCST. In addition, a quenching experiment was employed to elucidate the location of the fluorescent probes. In the PNIPAM latex, the probes were located where they were less quenchable as compared to the PNIPAM solution. It seems probable that the probes can penetrate into the crosslinked PNIPAM hydrogel and might reflect the inner environment of the hydrogel. The effect of salt on thermo‐sensitive behaviour was also detected by fluorescence analysis. On the other hand, the hydrogel microsphere prepared from poly(acryloyl pyrrolidine) (PAPr) showed a gradual change in fluorescence with temperature.
Emulsion polymerization and copolymerization in continuous reactor systems
Authors: Poehlein Gary W. 
Published: April 2007

AbstractContinuous reactors are important for commercial production of latex products and they can be useful tools for fundamental polymerization kinetics studies. Results are presented for four projects: (i) elimination of conversion oscillations in continuous stirred‐tank reactors (CSTR) by use of a tubular prereactor; (ii) use of a seed‐fed CSTR to measure free radical transport from monomer‐swollen latex particles; (iii) development of a continuous process as an alternative to a commercial batch process; and (iv) determination of copolymerization kinetic parameters with a steady‐state CSTR system.
Modification of polyvinyl chloride‐vinyl acetate latex by seed emulsion polymerization of acrylic monomers
Authors: Omi Shinzo , Shiiyama Eisuke , Sakurai Ken'Ichi , Yoshimoto Hiroyuki , Iso Mamoru , Nakano Akira , Nakamura Mamoru 
Published: April 2007

AbstractFundamental studies were carried out to modify the thermal properties of polyvinyl chloride (PVC)‐based latices. General features of composite PVC‐vinyl acetate (VAc) copolymer latices synthesized from the seed emulsion polymerization of acrylic monomers are reported, in particular, the observation of particle morphology and the measurements of minimum film formation temperature (MFT) and DSC spectra. Acrylic monomers used as modifiers were methyl methacrylate (MMA), n‐butyl methacrylate (BMA), methyl acrylate (MA), ethyl acrylate (EA), n‐butyl acrylate (nBA), and MMA‐nBA 75:25,50:50 and 25:75 wt%. Styrene whose polymer is incompatible with PVC‐VAc was used as a counterpart of compatible PMMA. Compatibility between seed and modifier polymer and the mode of operation, either batch (flooded and pre‐swollen) or semi‐batch (starved and no swelling), induced morphology differences, and consequently variations of thermal properties.
Castor‐oil‐modified epoxy resins as model systems of rubber‐modified thermosets. 2: Influence of cure conditions on morphologies generated
Authors: Ruseckaite Roxana A. , Hu Lijiang , Riccardi Carmen C. , Williams Roberto J. J. 
Published: April 2007

AbstractPhase separation during polymerization was studied in a model system consisting of a diepoxide based on the diglycidyl ether of bisphenol A (DGEBA), ethylenediamine (EDA) and variable amounts of castor oil (CO). Different events taking place during cure, i.e. phase separation, gelation and vitrification, are described in temperature versus time transformation diagrams (TTT), and conversion versus temperature phase diagrams. Thevconcentration (P) and average size (D̄) of dispersed‐phase particles followed opposite trends, i.e. one increased while the other decreased, when varying the castor oil concentration and the cure temperature. This is explained by assuming that the competition between nucleation and growth is determined by the viscosity at the cloud point, ηcp. Low values of ηcp favour growth over nucleation while the opposite is observed for conditions leading to high values of ηcp. The greater the conversion range between the cloud point and gelation, the broader the particle‐size distribution.
Castor‐oil‐modified epoxy resins as model systems of rubber‐modified thermosets. 3: Use of nucleating agent to modify the particle‐size distribution
Authors: Ruseckaite Roxana A. , Fasce Diana P. , Williams Roberto J. J. 
Published: April 2007

AbstractPhase separation during polymerization was produced in a model system consisting of a diepoxide based on the diglycidyl ether of bisphenol A (DGEBA), ethylenediamine (EDA), and a 15% mass fraction of either pure castor oil (CO) or a 95:5 mass ratio of CO and a polyester (PE) based on CO and oxalic acid. PE acted as a nucleating agent, leading to a significant decrease in the concentration of dispersed‐phase particles and the appearance of a fraction of large particles. Unimodal particle‐size distributions turned into bimodal distributions when adding PE, but the total volume fraction of dispersed phase remained constant. The addition of nucleating agents may be useful to develop formulations with optimum particle‐size distributions for toughening purposes.
Drop stabilisation by inorganic solids in suspension polymerisation: Effect of inorganic particle size using a wax model
Authors: Zhiping Wang , Brooks B. W. 
Published: April 2007

AbstractInorganic solids can be used for drop stabilisation in suspension polymerisation and, in some cases, the particle size can affect the drop stability significantly. Three theoretical models, each based on different theories for this drop stabilisation by inorganic solids, have been formulated. Experiments have been carried out using a wax model. These experiments were similar to those described previously [Brooks, B. W., Bygate. F. & Lane, A. C,Brit. Polym. J.,20(1988) 19‐24; Brooks, B. W.,Trans. I. Chem. E.,57(1979) 210‐12]. Particulate calcium phosphate, in different sizes, was used as the stabiliser. The theoretical models have been compared with the experimental results and it was found that two of the models bore some resemblance to the experimental results.
Synthesis and characterization of polyamides containing arylene sulfide‐sulfone groups
Authors: Joseph K. Abraham , Srinivasan M. 
Published: April 2007

AbstractPolyamides containing arylene sulfide as well as arylene sulfide‐sulfone linkages were prepared from bis(4‐phenylthio)dibenzoyl chloride (BPCl), 4,4′‐[sulfonylbis(4‐phenylthio)]dibenzoyl chloride (SPCl) and aromatic diamines both by solution and interfacial polymerization techniques. In the solution polymerization the effect of two different acid acceptors, lithium chloride and triethylamine, on inherent viscosity of the polyamides was studied. The effect of aromatic sulfone ether diamines and conventional aromatic diamines on viscosity and thermal properties of polyamides was also investigated. The polyamides prepared were characterized by IR, 1H NMR, elemental analysis, solution viscosity, thermogravi‐metry, differential scanning calorimetry and X‐ray diffraction. Thermal and physical properties of polyamides prepared from BPCl and SPCl were compared.
Monolayers of amylose ester derivatives
Authors: Itoh Takahiro , Matsumoto Mutsuo , Miyamoto Takeaki , Suzuki Hidematsu 
Published: April 2007

AbstractAmphiphilic polymers of amylose tri(n‐decanoate) (C10AS) and amylose tri(n‐octadecanoate) (C18AS) were prepared and examined with respect to their ability to form monolayers at the air‐water interface. The surface pressure‐area isotherm of C10AS was found to have a plateau region, indicating a monolayer‐to‐bilayer transition, while the isotherm for C18AS had no such plateau. Transmission electron microscopic observations of the transferred films revealed that C10AS formed a homogeneous monolayer film at a particular point of the π‐A isotherm, while C18AS gave no homogeneous film at any point of the isotherm. These results are different from those derived from the corresponding cellulose esters. The differences in the isotherms and fine structures of the transferred films are discussed in terms of the difference in chemical structure between amylose and cellulose.
Influence of sepiolite on spherulite growth rate in polyvinylidene fluoride‐based polyblends
Authors: Herrero Consuelo R. , Morales Enrique , Acosta Jose Luis 
Published: April 2007

AbstractThis work reports on the effects exerted by polymethylmethacrylate, polystyrene and sepiolite on several factors which affect spherulite growth of polyvinylidene fluoride, such as growth rate, nucleation factor and nucleation density. Interpretation of the data obtained will support the discussion on miscibility of binary polyvinylidene fluoride/polymethylmethacrylate and poly‐vinylidene fluoride/polystyrene, as well as the miscibilizing effect of sepiolite on both systems.
Crosslinking of atactic polypropylene by the system peroxide‐pentaerythritol tetraallyl ether
Authors: Borsig Eberhard , Lazár Milan , Malcherová Elena 
Published: April 2007

AbstractThe influence of the concentration of peroxide (mainly dicumyl peroxide) and pentaerythritol tetraallyl ether as coagent and the effect of temperature on the crosslinking of atactic polypropylene (a‐PP) with molar mass 12 000g/mol were investigated. Using this system, crosslinking of 40mass% of a‐PP at 160°C was obtained. The problems associated with the mechanism for crosslinking of a‐PP are discussed.