bluuebunny/crossref_metadata_2025_split huggingface dataset:
Technical note: The numerical solution of the system of 3‐D nonlinear elliptic equations with mixed derivatives and variable coefficients using fourth‐order difference methods
Authors: Mohanty R. K. , Jain M. K. 
Published: August 2005

AbstractIn this article, we report two fourth‐order difference methods for the numerical integration of the system of general 3‐D nonlinear elliptic equations subject to Dirichlet boundary conditions on a uniform cubic grid. When the coefficients of uxy, uyz, and uzx are not equal to zero and the coefficients of uxx, uyy, and uzz are equal, we require 27 grid points; when the coefficients of uxy, uyz, and uzx are equal to zero, we require only 19 grid points. The utility of the new methods is shown by testing the methods on various examples, including 3‐D steady state viscous incompressible Navier–Stokes' model equations and Poisson's equation in polar coordinates, which confirm the accurate and oscillation‐free solutions for large Reynolds numbers even in the vicinity of singularity. © 1995 John Wiley & Sons, Inc.
Long‐time behavior of some Galerkin and Petrov–Galerkin methods for thermoelastic consolidation
Authors: Murad Márcio A. , Loula Abimael F. D. 
Published: August 2005

AbstractNumerical analysis of some finite element methods for the quasi‐static thermoelastic consolidation problem of fluid‐filled porous materials is presented for the case of smooth exact solutions. Taking advantage of the exponential decay of the error in the initial data with time, error estimates describing the long‐time behavior of the semidiscrete approximation are presented and postprocessing techniques are proposed to improve the accuracy of the pore pressure, heat flux, and effective stress approximations. © 1995 John Wiley & Sons, Inc.
Concentrated protein solutions in the analytical ultracentrifuge
Authors: Lundh Søren 
Published: August 2005

AbstractConcentrated solutions of transferrin, albumin, immunoglobulin, chymotrypsinogen, transfer‐RNA, dextran, and polystyrene were pelleted in the analytical ultracentrifuge. The proteins developed a solvent/pellet boundary which was chracterized at equilibrium by an asymmetric schlieren peak with a “shoulder”. The schlieren curve was at the same level inside the protein pellet as in the solvent above the pellet, indicating that the protein molecules had been packed homogeneously. The protein concentration in the pellet ranged from 0.6 to 0.7 g/ml. Immediately after deceleration was begun, the “shoulder” of the pellet boundary changed into a very sharp peak, leading to a boundary composed of two schlieren peaks. Sedimentation rates were measured for transferrin solutions at concentrations up to 0.3 g/ml.
The dependence of craze velocity on the pressure and temperature of the environmental gas
Authors: Brown Norman , Metzger Bruce D. 
Published: August 2005

AbstractThe craze velocity was determined for poly(chlorotrifluoroethylene) (PCTFE) in CH4 and for PCTFE, polystyrene, and poly(methyl methacrylate) in N2. It was found that for temperatures near the boiling point the velocity and number of crazes depended on the relative pressure given by P exp[‐(Qv/R) (TB−1 ‐ T−1)], where P is the pressure, Qv is the heat of vaporization, and TB is the boiling point. The craze velocity was related to the coverage of the adsorbed gas. For coverages corresponding to a few monolayers the logarithm of the velocity was proportional to the relative pressure. As the temperature increases from TB, the creep rate decreases because gas desorbs with increasing temperature; the creep rate attains a minimum value at a temperature where the general process of thermally activated deformation becomes dominant.
Effect of diphenylbutadiyne on the free radical polymerization of vinyl monomers in solution
Authors: Navarro Rosa Elena , Ogawa Takeshi 
Published: August 2005

AbstractThe free radical polymerization of vinyl monomers such as styrene, methylmethacrylate, methyacrylate, acrylonitrile, vinylacetate, etc. in the presence of diphenylbutadiyne, was investigated. Both rates of polymerization and molecular weights of polymer decreased by the addition of diphenylbutadiyne. The degree of retardation depended on the stability of propagating radicals. The butadiyne does not react with the propagating radicals having high Q values, but it seems to trap the radicals temporarily thus retarding the polymerization
Kinetics of photopolymerization of acrylamide in AOT reverse micelles
Authors: Carver M. T. , Dreyer U. , Knoesel R. , Candau F. , Fitch R. M. 
Published: August 2005

AbstractThe kinetics of the photoinitiated polymerization of acrylamide in toluene/AOT/water inverse microemulsions have been examined for systems initiated by AIBN or a dye: triethanolamine redox reaction. The rates of polymerization were determined by dilatometry, the data being corrected for the effect of reaction exotermicity. For both the oil‐soluble and the water‐soluble initiating systems, the rate of polymerization was found to be proportional to the first power of the incident light intensity. For AIBN‐initiated systems, the rate of polymerization was also found to be proportional to the first power of the initiator concentration. The molecular weights of the polymers produced were independent of the rates of polymerization and initiation. These results suggest that exclusively monoradical termination, involving a degradative chain transfer, is occurring in these systems
Effect of solution components on the termination mechanism in acrylamide microemulsion polymerizations
Authors: Carver Michael T. , Candau Françoise , Fitch Robert M. 
Published: August 2005

AbstractA study of the effect of the various solution components on the kinetics of the polymerization of acrylamide in water/oil (w/o) microemulsions has been performed. For the polymerizations with toluene as the continuous phase, both the rate of polymerization, Rp, and the molecular weight of the polyacrylamide were found to be first order in monomer concentration. Furthermore, for the low temperatures (10°C) involved in these experiments, nondegradative chain transfer to monomer appears to be insignificant. When the continuous‐phase solvent was changed, an exponential dependence, X, of Rp on the incident light intensity in the order of toluene (X = 1.06) > heptane (X = 0.73) > benzene (X = 0.55) was found. Thus, the monoradical termination found in the toluene microemulsions is likely due to degradative transfer to toluene, forming a stable benzyl radical, while polymerization in benzene (no labile hydrogen atoms) leads to biradical termination
Polypropylene ionomers
Authors: Landoll L. M. , Breslow D. S. 
Published: August 2005

AbstractThe preparation and properties of highly crystalline ionomers formed by the copolymerization of propylene and low levels of ethylcholoroaluminium 10‐undecenoate have been investigated. Few of the variables studied had dramatic effects on the copolymerization. Thus, a five‐fold increase in undecenoate concentration gave only about a 20% increase in acid incorporation into the copolymer. Increasing temperature resulted in increased acid content, but handling problems in a I gal stirred reactor limited polymerization of 80°C. Rates were lowered in the presence of complex, but the effect was minimized by hydrogen. Rheological measurements showed an increase in low shear melt viscosity of the pottasium salts by up two orders of magnitude relative to the acid from. Ionomers containing two or more carboxyl groups as their potassium salts, and having a broad molecular weight distribution, had an extended rubbery plateau range, covering most of the shear ranges of normal processing. The zero‐shear activation energy for viscous flow was 42 kcal, comparable to ABS and polystyrene. These ionomers are promising candidates for thermoforming applications
Copolymerization of toluene with tetrafluoromethane or octafluorocyclobutane by plasma technique
Authors: Ye Mu , Chen Jie , Yang Zhenhua , Lu Lizhen , Li Shaoyu , Sun Ying 
Published: August 2005

AbstractPlasma copolymerization of toluene with tetrafluoromethane or octafluorocyclobutane was carried out in a capacitively coupled tubular reactor with external electrodes. The polymer structure was characterized by means of XPS, IR, and pyrolysis/GC/MS and the condensates of the gases in the plasma reaction chamber were measured by GC–MS. It is observed that the monomers undergo a plasma states polymerization in a glow discharge and only those monomer fragments with sufficient reactivity join the copolymerization. The types of fluorine‐containing groups in the polymer structure are related to the chemical structure of the flurocarbons. The fluorine content depends upon the discharge power, the system pressure, and the fraction of fluorocarbons in the monomers
Thermal degradation processes in aliphatic polydithiocarbonates
Authors: Montaudo Giorgio , Puglisi Concetto , Berti Corrado , Marianucci Elisabetta , Pilati Francesco 
Published: August 2005

AbstractThe thermal degradation of three aliphatic polythiocarbonates was investigated by direct pyrolysis in the ion source of a mass spectrometer operating both in electron and chemical ionization modes. The overall evidence indicates that these polymers start decomposing at about 250–280°C by an end‐biting process initiating from the SH end‐groups, which produces a mixture of cyclic sulfides, disulfides, and dithiocarbonates. Another decomposition step is observed at higher temperature (ca. 350–370°C), producing essentially the same compounds evolved in the first stage, but with significant differences in their relative abundances. An intramolecular exchange (back‐biting) process is believed to be responsible for the second thermal decomposition stage
Side‐chain liquid crystalline polymers containing 4‐[2‐(S)‐methyl‐1‐butoxy]‐4′‐(11‐undecanyl‐1‐oxy)‐α‐methylstilbene side groups
Authors: Percec Virgil , Hahn Bruce 
Published: August 2005

AbstractThe synthesis and characterization of polymethacrylate, polyacrylate, poly(methylsiloxane), and 1,3,5,7‐tetramethylcyclotetrasiloxane containing chiral 4‐[2‐(S)‐methyl‐1‐ butoxy]‐4′‐(11‐undecanyl‐1‐oxy)‐α‐methylstilbene side groups are described. All polymers exhibit an enantiotropic SA mesophase and side‐chain crystallization. The 1,3,5,7‐tetramethylcyclotetrasiloxane containing mesogenic side groups represents a mixture of four stereoisomers and displays a monotropic SA mesophase
The ozonolysis of butyl and halobutyl elastomers
Authors: Ho K. W. , Guthmann J. E. 
Published: August 2005

AbstractThe ozonolysis of butyl elastomer and its halogenated derivatives, as well as their model compounds in hexane, was studied. It was found that while the ozonolysis of butyl and chlorobutyl elastomers involves the normal cleavage of olefinic double bonds, the mechanism of ozonolysis of bromobutyl elastomer is more complicated. In the presence of ozone, bromobutyl elastomer was found to rearrange from the exomethylene structure to the bromomethyl structure, thereby generating more in‐chain double bonds. This reaction provides an explanation as to why bromobutyl elastomer degrades faster and to a greater extent than chlorobutyl elastomer containing the same number of olefinic double bonds. Different additives were found to have different effects on the chain scission and rearrangement of bromobutyl elastomer. Diphenylamine and triisopropyl phosphite are much more effective than hexylamine and 2,6‐di‐tert‐butyl cresol in inhibiting the chain scission of the bromobutyl elastomer and diphenylamine is more effective than triisopropyl phosphite in suppressing the rearrangement of this elastomer
Crystallization behavior and morphology of poly(butylene succinate) modified with rosin maleopimaric acid anhydride
Authors: Liu Xiaoqing , Li Chuncheng , Guan Guohu , Yuan Xuepei , Xiao Yaonan , Zhang Dong 
Published: August 2005

AbstractThe melting behavior, crystallization behavior, and morphology of PBSR, which is Poly(butylene succinate) modified with rosin maleopimaric acid anhydride (RMA), were investigated with differential scanning calorimetry (DSC) and polarized optical microscope (POM). The multiple endotherms were ascribed to the recrystallization during DSC measurement and the equilibrium melting temperature determined by the Peak L, which was associated with the fusion of the crystals grown by normal primary crystallization, was 125.9 °C. After the kinetic parameters for isothermal crystallization of PBSR were determined by Avrami equation, to make a detailed regime transition analysis, the well‐established Lauritzen–Hoffman equation was employed. The results indicated that there were two regimes, regime II and regime III, in the range of higher and lower crystallization temperature, respectively. The regime transition temperature is about 81 °C. At last, the spherulitic morphologies of PBSR after being crystallized isothermally at different temperature were observed with the help of POM. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2694–2704, 2005
Surface Analysis of Plasma Deposited Polymer Films, 5
Authors: Oran Umut , Swaraj Sufal , Friedrich Jörg F. , Unger Wolfgang E. S. 
Published: August 2005

AbstractSummary: The effect of the composite plasma parameter P/F, where P is the plasma power and F is the monomer flow rate, on the chemical character of pulsed plasma deposited allyl alcohol films was investigated by ToF‐SSIMS. Information on the unsaturated character, the cross‐linked and/or branched character of the plasma polymer films was derived in detail. The problem of the retention of OH groups in plasma deposited allyl alcohol films was elucidated in detail using SSIMS data. The lowest conversion rate from the monomer's hydroxyl groups to other oxygen functionalities in the plasma was concluded for the plasma polymer film produced at a P/F ratio of 0.05 W · sccm−1. It was found that the overall oxygen content of the films decreased vs. increasing P/F ratio. Because the freshly prepared films were investigated without air exposure, ageing on ambient air could be studied in detail. It was found that in the case of plasma deposited allyl alcohol films the ageing on air is probably based on two competing processes which are discussed in detail. Additionally, a review of literature data on the characterization of plasma deposited allyl alcohol films is given.Reduced SSIMS data of plasma deposited allyl alcohol films prepared at different P/F ratios. Retention of the OH groups were derived from the (m − H)+/(m + H)+ intensity ratios. Note that the arrow indicates the increase for the retention of OH groups.magnified imageReduced SSIMS data of plasma deposited allyl alcohol films prepared at different P/F ratios. Retention of the OH groups were derived from the (m − H)+/(m + H)+ intensity ratios. Note that the arrow indicates the increase for the retention of OH groups.
Surface Analysis of Plasma‐Deposited Polymer Films, 6
Authors: Swaraj Sufal , Oran Umut , Lippitz Andreas , Friedrich Jörg F. , Unger Wolfgang E. S. 
Published: August 2005

AbstractSummary:XPS and NEXAFS spectroscopy results were used for chemical characterization of pulsed plasma deposited allyl alcohol films before and after exposure to ambient air. The influence of the composite plasma parameter, effective plasma power (P) to monomer flow rate (F) ratio on the spectroscopic results was investigated. From this data, information about the chemical character of the plasma polymerized films, such as retention of the hydroxyl groups in the deposited sample, the amount of long living radicals and branching and/or crosslinking was derived. A high degree of hydroxyl retention was observed, which, however, decreased along with the oxygen content of the film, as the P/F ratio increased. A trend in the extent of the oxygen loss according to the variation of the P/F ratio was deduced, which agrees with earlier ToF‐SSIMS findings (Plasma Process. Polym.2005,2, 563).XPS spectra of plasma deposited allyl alcohol in situ and after exposure to ambient air (reference sample: poly(vinyl alcohol)).magnified imageXPS spectra of plasma deposited allyl alcohol in situ and after exposure to ambient air (reference sample: poly(vinyl alcohol)).
Interaction of Photons with Polymers: From Surface Modification to Ablation
Authors: Lippert Thomas 
Published: August 2005

AbstractSummary: This work reviews the interaction of photons with polymers with an emphasis on UV laser ablation and surface modification using VUV lamps. Laser ablation of polymers is an established process in industrial applications, but the mechanisms of ablation are still controversial. Different polymers, such as poly(methyl methacrylate), polyimides and specially designed polymers are used as examples to show that the mechanism is a mixture of photochemical and photothermal features which are closely related to the polymer structure and properties. Different approaches to probe the ablation mechanisms and to improve ablation are discussed. Photoactive groups have been introduced into the polymer structure to improve the quality of ablation and to elucidate the ablation mechanisms. The experimental techniques to probe the ablation mechanism range from time‐resolved measurements, such as shadowgraphy, ToF‐MS, and ns‐surface interferometry to variations of the irradiation wavelengths and pulse lengths. The necessity for a critical evaluation of the experimental procedures and analysis is discussed exemplary for polyimides. The data for different types of polyimides are mixed up and some experimental procedures are possibly causing problems for the data evaluation. Various recent trends for laser ablation, such as ultrafast ablation or VUV ablation are also discussed. Surface modifications of polymers using VUV photons from lamps are discussed for oxidation and nitriding of poly dimethylsiloxane (PDMS) and polyolefines. The mechanism of the PDMS surface oxidation is presented in detail.Ablation pattern in TP1 created by 308 nm irradiation using a gray tone phase mask.magnified imageAblation pattern in TP1 created by 308 nm irradiation using a gray tone phase mask.
Genome instability as a cause of ageing and cancer: Implications of RecQ helicases
Authors: Skouboe Camilla , Bjergbaek Lotte , Andersen Anni H. 
Published: August 2005

AbstractMembers of the RecQ helicase family are mutated in several human genomic instability syndromes, such as Werner and Bloom syndromes. The syndromes are characterized by premature ageing and cancer predisposition, respectively, and are therefore extensively used as model systems for studies of ageing and cancer. RecQ homologues are widely expressed enzymes, and genetic and biochemical investigations have pointed to their involvement in homologous recombinational DNA repair pathways. In the review we will focus on the implications of RecQ helicases for genome maintenance with specific emphasis on the homologues found in yeast.
Impaired left ventricular relaxation in type 2 diabetic rats is related to myocardial accumulation of Nɛ‐(carboxymethyl) lysine
Authors: Schäfer Stefan , Huber Jochen , Wihler Cornelia , Rütten Hartmut , Busch Andreas E. , Linz Wolfgang 
Published: August 2005

AbstractMyocardial dysfunction in the absence of myocardial ischemia is frequent in patients with diabetes mellitus but the underlying pathomechanism is unclear. We investigated whether accumulation of advanced glycation end products (AGEs) in the diabetic myocardium is related to its functional abnormalities.In 11 male homozygous Zucker diabetic fatty rats (ZDF/Gmi‐fa/fa) aged 37 weeks (OBESE) and 11 non‐obese, non‐diabetic littermates (LEAN), we measured left ventricular function (pressure–volume catheter) and levels of Nɛ‐(carboxymethyl) lysine (CML), a prototypical AGE, in serum and the left ventricle (competitive enzyme linked immuno‐assay).Overt diabetes mellitus (HbA1c >9%) was present in all OBESE animals but not in LEAN. Systolic left ventricular function was not different between the groups, but the markers of left ventricular relaxation, dP/dtmin and the relaxation constant τ, were impaired in OBESE. In parallel, CML levels were increased in serum (273±15 vs. 197±10 ng/ml, p<0.05) and in the left ventricle (18.4±1.1 vs. 12.5±2.0 ng/mg protein, p<0.05) in OBESE compared to LEAN. There was a linear correlation between τ and the left ventricular CML levels (r=0.65; p<0.05).We conclude that type 2 diabetes is associated with predominant left ventricular diastolic dysfunction. Myocardial accumulation of advanced glycation end products may contribute to relaxation abnormalities in type 2 diabetes.
Chronic pancreatitis patients show hyperalgesia of central origin: A pilot study
Authors: Buscher Hessel C.J.L. , Wilder‐Smith Oliver H.G. , van Goor Harry 
Published: August 2005

AbstractBackground The pain of chronic pancreatitis remains challenging to manage, with treatment all too often being unsuccessful. A main reason for this is lacking understanding of underlying mechanisms of chronic pain in these patients.Aim To document, using somatic quantitative sensory testing, changes in central nervous system processing (neuroplasticity) associated with chronic pancreatitis pain and thus gain insight into underlying pain mechanisms.Patients and methods We studied 10 chronic pancreatitis patients on stable opioid analgesic medication. Ten matched surgical patients without pain served as controls. Pain verbal numeric rating scores (NRS) and thresholds to electric skin stimulation and pressure pain were measured in dermatomes T10 (pancreatic area), C5, T4, L1 and L4.Results The pancreatitis patients had a median NRS pain score of 5 (range 3–8). Electric sensation and pain thresholds were significantly increased in the pancreatic region, tending to be more so in female pancreatitis patients. Pressure pain thresholds were significantly lower in pancreatitis patients than in controls, with men tending towards greater generalised relative hyperalgesia than women.Conclusions Chronic pancreatitis patients show pronounced generalised deep hyperalgesia that is present despite opioid therapy. These signs, consistent with central sensitisation, appear relatively more prominent in men than women. There is also evidence suggesting that women may have a better segmental inhibitory response than men, possibly explaining their relatively less prominent generalised deep tissue hyperalgesia compared to men.
Thyroid cancer in pregnancy
Authors: Yasmeen S. , Cress R. , Romano P.S. , Xing G. , Berger‐Chen S. , Danielsen B. , Smith L.H. 
Published: August 2005

AbstractObjective: To compare stage at diagnosis, treatment and survival among pregnant women with thyroid cancer to non‐pregnant women with thyroid cancer, and to assess the impact of treatment on maternal and perinatal outcomes. Methods: A database containing maternal and newborn discharge records linked to the California Cancer Registry was queried to obtain information on all thyroid cancers from 1991–1999. Women with thyroid cancer occurring during pregnancy were compared to age‐matched non‐pregnant women with thyroid cancer. Results: 595 cases of thyroid cancers were identified (129 antepartum and 466 postpartum). About 64% of thyroid cancers were diagnosed at stage 2 among pregnant women versus 58% among non‐pregnant controls. The odds of thyroid cancer were 1.5 times higher among Asian/Pacific Islanders than among Non‐Hispanic White women. Pregnancy had no significant effect on mortality after diagnosis of thyroid cancer. Thyroidectomy during pregnancy was not associated with adverse maternal or neonatal outcomes. Conclusions: Thyroid cancer discovered during or after pregnancy does not appear to have a significant impact on the prognosis of the disease.