bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of 08CH18N10T stainless steel corrosion in subcritical water by electrochemical noise analysis
Authors: Kučera P. , Macák J. , Sajdl P. , Novotný R. 
Published: September 2008

AbstractThe corrosion behaviour of pressurized water reactor (PWR) steam generator tube material (08CH18N10T steel) was studied by electrochemical noise (EN) measurements and electrochemical impedance spectroscopy in high‐temperature water at 280 °C and 8 MPa. Long‐term measurements were performed in two electrolytes: (i) deionised water alkalized to pH25 = 9.5 by KOH; (ii) the same electrolyte with 200 ppm of chlorides added (as KCl). The noise data were processed by two filtering methods and the noise resistance and spectral noise resistance values were calculated. Different contributions to the total impedance were identified and the polarization resistance values were calculated from EIS data. Noise and polarization resistances were compared and the influence of filtering methods was discussed. Instantaneous corrosion data were transformed to integral ones and comparison with mean corrosion current estimated from the oxide thickness was made. It was confirmed that the crucial point of EN analysis is selection of proper cut‐off frequency in high‐pass fast Fourier transform (HP‐FFT).
GD‐OES and electrochemical study of Ce containing conversion layers of hot dip galvanised and by Sendzimir process continuously hot dip galvanised steel plates
Authors: Kőszegi S. , Felhősi I. , Kálmán E. 
Published: September 2008

AbstractThe present work is focused on the conversion layers of hot dip galvanised and continuously hot dip galvanised steel sheets produced by ISD DUNAFERR, Co., Ltd. The conversion coatings on the galvanised steel plates were produced by dipping the plates into solutions of rare earth salts for different immersion periods. The applied rare earth salts were, cerium nitrate and cerium chloride, respectively. The corrosion resistance of the treated plates was tested by DC polarisation measurements and electrochemical impedance spectroscopic method (EIS). The most promising conversion layers were subjected to special corrosion test modelling the effect of the squeezing of plates or coils during storage and delivering and the humidity, simultaneously. The qualitative properties of the corroded surface were tested by glow discharge optical emission spectroscopy (GD‐OES).
Intrinsic Viscosity of Aqueous Solutions of Carboxymethyl Guar in the Presence and in the Absence of Salt
Authors: Badiger Manohar V. , Gupta Nivika R. , Eckelt John , Wolf Bernhard A. 
Published: September 2008

AbstractIntrinsic viscosities were determined for solutions of CMG in pure water and 0.9 wt.‐% aqueous NaCl. To avoid the 0/0‐type extrapolation typical for Huggins plots, a new procedure was used. For CMG and pure water, this requires only two adjustable parameters: the specific hydrodynamic volume of the polymer in the limit of infinite dilution and a hydrodynamic interaction parameter. The intrinsic viscosity of CMG (no salt) at room temperature is 6 050 mL · g−1; approximately half as large as that of Na‐PSS of comparable molar mass. The ratio of the intrinsic viscosities with and without salt is ≈7 for CMG, as compared to >100 for Na‐PSS. The reasons for the different behaviors of the two types of polyelectrolytes are being discussed.magnified image
Assembled Structures and Chiroptical Properties of Amphiphilic Block Copolymers Synthesized by RAFT Polymerization of N‐Acryloyl‐L‐alanine
Authors: Mori Hideharu , Matsuyama Motonobu , Endo Takeshi 
Published: September 2008

AbstractAmino acid‐based amphiphilic block copolymers involving poly(N‐acryloyl‐L‐alanine), poly(A‐Ala‐OH), which exhibits a characteristic chiroptical property and pH‐dependent solubility, have been synthesized by reversible addition‐fragmentation chain transfer (RAFT) polymerization. The direct polymerization of A‐Ala‐OH without any protecting chemistry using the dithiocarbamate‐terminated polystyrene or poly(N‐acryloyl‐L‐phenylalanine methyl ester) as a macrochain transfer agent produced well‐defined amphiphilic block copolymers. The self‐assembly behaviors and chiroptical properties of these amphiphilic block copolymers in selective solvents were investigated by dynamic light scattering, circular dichroism, and UV–Vis spectroscopic methods.magnified image
Miscibility of Blends of Biodegradable Polymers and Copolymers with Different Plasticizers
Authors: García‐Lopera Rosa , Monzó Isidro S. , Porcar Iolanda , Abad Concepción , Campos Agustín 
Published: September 2008

AbstractMiscibility between components of different plasticizer(A)/solvent(B)/biodegradable polymer(C) ternary systems with H‐bonding has been compared. Systems were formed by two H‐donor phenolic plasticizers, 4‐nonylphenol (NP) and 4:4′‐dihydroxydiphenylmethane (BPF); an H‐acceptor solvent, epichlorohydrin (ECH); and H‐acceptor poly(3‐hydroxybutyrate) (PHB) or poly[(3‐hydroxybutyrate)‐co‐(3‐hydroxyvalerate)] (PHBHV) copolymers. Blend miscibility is the result of the balance of three competitive H‐bondings: plasticizer self‐association (AA), plasticizer‐solvent (AB) and plasticizer‐polymer (AC) interassociations. The strength and extent of such specific interactions have been experimentally monitored by fluorescence spectroscopy either in solution or in solid state. Theoretical modelling has been conducted with a recent thermodynamic approach based on two free‐energy excess functions.magnified image
Cure versus Flow in Dispersed Chip‐Underfill Materials
Authors: Teyssandier Fabien , Sun Yang Y. , Wong Ching P. , Love Brian J. 
Published: September 2008

AbstractThe relative stability of chip‐underfill composite materials was modeled as a function of glass filler concentration between 10 and 70 wt.‐%, filler particle size (between 5 and 25 microns), and the curing temperature of the resin (150 vs. 180 °C), yielding different dynamic viscosity profiles. The stability was gauged using a modified sigmoidal chemorheology model for the dynamic viscosity, and incorporating the time‐dependent viscosity into a model for Stokes' law of sedimentation. We also incorporated a hindered sedimentation term, due to filler concentration due to the higher loadings. Several important findings were observed. First, it appears to be the high concentration of filler that is maintaining the stability of these dispersions during cure. Smaller concentrations of the same particles were predicted to have a larger sedimentation velocity leading to stratification in the resin with time. Second, higher cure temperatures led to a shorter period of sedimentation in a pre‐cured state and resulted in less sedimentation, even though there was probably a slightly smaller viscosity in the pre‐cured condition. While these process models adequately describe the physics of the competitive processes of cure and sedimentation, a full picture may be incomplete without a larger determination of how this also affects polymerization shrinkage and residual shear stress upon cure.magnified image
Tumor suppressor gene Co‐operativity in compound Patched1 and suppressor of fused heterozygous mutant mice
Authors: Svärd Jessica , Rozell Björn , Toftgård Rune , Teglund Stephan 
Published: September 2008

AbstractDysregulation of the Hedgehog signaling pathway is central to the development of certain tumor types, including medulloblastoma and basal cell carcinoma (BCC). Patched1 (Ptch1) and Suppressor of fused (Sufu) are two essential negative regulators of the pathway with tumor suppressor activity. Ptch1+/− mice are predisposed to developing medulloblastoma and rhabdomyosarcoma, while Sufu+/− mice develop a skin phenotype characterized by basaloid epidermal proliferations. Here, we have studied tumor development in Sufu+/−Ptch1+/− mice to determine the effect of compound heterozygosity on the onset, incidence, and spectrum of tumors. We found significantly more (2.3‐fold) basaloid proliferations in Sufu+/−Ptch1+/− compared to Sufu+/− female, but not male, mice. For medulloblastoma, the cumulative 1‐yr incidence was 1.5‐fold higher in Sufu+/−Ptch1+/− compared to Ptch1+/− female mice but this strong trend was not statistically significant. Together this suggests a weak genetic interaction of the two tumor suppressor genes. We noted a few rhabdomyosarcomas and pancreatic cysts in the Sufu+/−Ptch1+/− mice, but the numbers were not significantly different from the single heterozygous mice. Hydrocephalus developed in ∼20% of the Ptch1+/− and Sufu+/−Ptch1+/− but not in Sufu+/− mice. Interestingly, most of the medulloblastomas from the Sufu+/−Ptch1+/− mice had lost expression of the remaining Ptch1 wild‐type allele but not the Sufu wild‐type allele. On the contrary, Sufu as well as Gli1 and Gli2 expression was upregulated in the medulloblastomas compared to adult cerebellum in Ptch1+/− and Sufu+/−Ptch1+/− mice. This suggests that Sufu expression may be regulated by Hedgehog pathway activity and could constitute another negative feedback loop in the pathway. © 2008 Wiley‐Liss, Inc.
Constructive approximation of solution for fourth‐order nonlinear boundary value problems
Authors: Du Juan , Cui Minggen 
Published: September 2008

AbstractIn this paper, we obtain a sequence of approximate solution converging uniformly to the exact solution of a class of fourth‐order nonlinear boundary value problems. Its exact solution is represented in the form of series in the reproducing kernel space. The n‐term approximation un(x) is proved to converge to the exact solution u(x). Moreover, the derivatives of un(x) are also convergent to the derivatives of u(x). Copyright © 2008 John Wiley & Sons, Ltd.
Gradient and dilatational stabilizations for stress‐point integration in the element‐free Galerkin method
Authors: Duan Qinglin , Belytschko Ted 
Published: September 2008

AbstractStabilized stress‐point integration schemes based on gradient stabilization and dilatational stabilization methods are presented for linear elastostaticity problems in the framework of element‐free Galerkin (EFG) method. The instability in stress fields associated with the stress‐point integration is treated by the addition to the Galerkin weak form of stabilization terms which contain product of the gradient of the residual or the trace of the gradient of the residual; the latter is called dilatational stabilization. Numerical results show that the oscillations in the stress fields are successfully removed by the presented stabilization methods, and that the convergence and stability properties of direct stress‐point integration are greatly improved. These stabilization methods are particularly suitable for the solution of non‐linear continua with explicit time integration methods. Copyright © 2008 John Wiley & Sons, Ltd.
A superconvergent point interpolation method (SC‐PIM) with piecewise linear strain field using triangular mesh
Authors: Liu G. R. , Xu X. , Zhang G. Y. , Nguyen‐Thoi T. 
Published: September 2008

AbstractA superconvergent point interpolation method (SC‐PIM) is developed for mechanics problems by combining techniques of finite element method (FEM) and linearly conforming point interpolation method (LC‐PIM) using triangular mesh. In the SC‐PIM, point interpolation methods (PIM) are used for shape functions construction; and a strain field with a parameter α is assumed to be a linear combination of compatible stains and smoothed strains from LC‐PIM. We prove theoretically that SC‐PIM has a very nice bound property: the strain energy obtained from the SC‐PIM solution lies in between those from the compatible FEM solution and the LC‐PIM solution when the same mesh is used. We further provide a criterion for SC‐PIM to obtain upper and lower bound solutions. Intensive numerical studies are conducted to verify these theoretical results and show that (1) the upper and lower bound solutions can always be obtained using the present SC‐PIM; (2) there exists an αexact∈(0, 1) at which the SC‐PIM can produce the exact solution in the energy norm; (3) for any α∈(0, 1) the SC‐PIM solution is of superconvergence, and α=0 is an easy way to obtain a very accurate and superconvergent solution in both energy and displacement norms; (4) a procedure is devised to find a αprefer∈(0, 1) that produces a solution very close to the exact solution. Copyright © 2008 John Wiley & Sons, Ltd.
Fast single domain–subdomain BEM algorithm for 3D incompressible fluid flow and heat transfer
Authors: Ravnik Jure , Škerget Leopold , Žunič Zoran 
Published: September 2008

AbstractIn this paper acceleration and computer memory reduction of an algorithm for the simulation of laminar viscous flows and heat transfer is presented. The algorithm solves the velocity–vorticity formulation of the incompressible Navier–Stokes equations in 3D. It is based on a combination of a subdomain boundary element method (BEM) and single domain BEM. The CPU time and storage requirements of the single domain BEM are reduced by implementing a fast multipole expansion method. The Laplace fundamental solution, which is used as a special weighting function in BEM, is expanded in terms of spherical harmonics. The computational domain and its boundary are recursively cut up forming a tree of clusters of boundary elements and domain cells. Data sparse representation is used in parts of the matrix, which correspond to boundary‐domain clusters pairs that are admissible for expansion. Significant reduction of the complexity is achieved.The paper presents results of testing of the multipole expansion algorithm by exploring its effect on the accuracy of the solution and its influence on the non‐linear convergence properties of the solver. Two 3D benchmark numerical examples are used: the lid‐driven cavity and the onset of natural convection in a differentially heated enclosure. Copyright © 2008 John Wiley & Sons, Ltd.
Optimal control approach for robust control design of neutral systems
Authors: Lin Yu‐Chen , Lin Chun‐Liang 
Published: September 2008

AbstractThis paper proposes an optimal control approach for a robust control design problem of the neutral type time‐delay systems, taking parameter uncertainties and state delay into account. The robust control design problem can be equivalently transformed into an optimal control problem, and the amount of plant uncertainties is indirectly reflected in the performance index. By introducing algebraic manipulations and appropriate uncertainty descriptions, the uncertain dynamical system can not only achieve stability, but can also reach the guaranteed level of performance. A suitable linear state feedback control law is characterized via Lyapunov stability theory to ensure quadratic stability and performance robustness of the closed‐loop system. Copyright © 2008 John Wiley & Sons, Ltd.
The design of excitation pulses for spin systems using optimal control theory: With application to NMR spectroscopy
Authors: Gershenzon Naum I. , Miller David F. , Skinner Thomas E. 
Published: September 2008

AbstractThis paper considers the use of optimal control theory in designing radio frequency excitation pulses for magnetic spin systems satisfying Bloch dynamics. Such pulses are required in applications of nuclear magnetic resonance to initially transfer sample magnetization vectors to the transverse plane. Once transferred, signals released by nuclei as they respond to a static magnetic field normal to the transverse plane are then analyzed and interpreted. Continuous time deterministic optimal control theory is employed to determine time‐dependent pulse amplitudes and frequencies that minimize the distance between final magnetization vectors and a chosen target vector. Pulses are designed to excite a range of resonant frequencies and to tolerate miscalibration errors in applied fields. The model presented permits a unified treatment of the control problem as considered by a variety of authors, and a thorough mathematical analysis of the existence, and characteristics of, optimal excitation pulses. Practical numerical algorithms for designing optimal pulses are given, and the effectiveness of the algorithms is illustrated by comparing the pulses that they generate with those commonly used in high‐resolution spectroscopy. Copyright © 2008 John Wiley & Sons, Ltd.
Long‐term use of antihypertensive drugs and risk of cancer
Authors: Assimes Themistocles L. , Elstein Eleanor , Langleben Adrian , Suissa Samy 
Published: September 2008

AbstractPurposeDetermine the relative risk of cancer users of commonly prescribed antihypertensive drugs with a focus on documenting risk in long‐term users (>7.5 years).MethodsWe conducted a nested case–control study using the Saskatchewan Health databases. Cancer risks in users of β‐blockers, calcium channel blockers (CCBs), and rennin‐angiotensin system inhibitors (RASIs), respectively, were compared to risks in users of thiazide diuretics.ResultsA total of 11 697 first cases of cancer and the subset of 6918 subjects who died from cancer were each matched to 10 controls. The mean total duration of use of the four classes of antihypertensive drugs (estimated by dispensation of prescriptions) ranged from 3.6 to 5.7 years. A subgroup of cases was exposed long term (mean total duration of use: 9.7–11.4 years, range: 7.5–23.1 years). Modest differences in risk between users of the four classes were detected for colon, head & neck, lung, and hematological cancers but none of these associations demonstrated a clear dose response relationship for both first cancer and fatal cancer. Otherwise, for cancer at all sites combined and for the four most common cancers, we were able to rule out, with reasonable confidence, small to modest differences in the risk of cancer among users of any duration (upper 95% confidence intervals (CIs): 1.45) and modest to large differences in risk among long‐term users (upper 95%CI: 3.06).ConclusionsThe long‐term use of commonly prescribed classes of antihypertensive drugs does not appear to promote or initiate cancer. Copyright © 2008 John Wiley & Sons, Ltd.
Immiscibility–miscibility phase transitions in blends of poly(L‐lactide) with poly(methyl methacrylate)
Authors: Li Shu‐Hsien , Woo Eamor M 
Published: September 2008

AbstractBACKGROUND: The nature of phase transitions and apparently irreversible phase homogenization upon heating in blends of biodegradable poly(L‐lactide) (PLLA) with poly(methyl methacrylate) (PMMA) were proven using differential scanning calorimetry, polarized optical microscopy, scanning electron microscopy and 1H NMR spectroscopy. The complex phase behaviour in this blend system is puzzling and is a matter of debate; this study attempts to clarify the true nature of the phase behaviour.RESULTS: A PMMA/PLLA blend is immiscible at ambient temperature but can become miscible upon heating to higher temperatures with an upper critical solution temperature (UCST) at 230 °C. The blends, upon rapid quenching from the UCST, can be frozen into a quasi‐miscible state. In this state, the interaction strength was determined to be χ12 = − 0.15 to − 0.19, indicating relatively weak interactions between the PLLA ester and PMMA acrylic carbonyl groups.CONCLUSION: The absence of chemical exchange reactions above the UCST and phase reversibility back to the original phase separation morphology, assisted by solvent re‐dissolution, in the heat‐homogenized PLLA/PMMA blend was shown. Verification of UCST behaviour, phase diagrams and solvent‐assisted phase reversibility were experimentally demonstrated in PMMA/PLLA blends. Copyright © 2008 Society of Chemical Industry
In situ proteomics with imaging mass spectrometry and principal component analysis in the Scrapper‐knockout mouse brain
Authors: Yao Ikuko , Sugiura Yuki , Matsumoto Mineo , Setou Mitsutoshi 
Published: September 2008

AbstractImaging MS is emerging as a useful tool for proteomic analysis. We utilized this technique to analyze gene knockout (KO) mice in addition to traditional 2‐DE analysis. The Scrapper‐knockout (SCR‐KO) mouse brain showed two types of neurodegenerative pathologies, the spongiform neurodegeneration and shrinkage of neuronal cells. 2‐DE analysis of the whole brain lysates of SCR‐KO mice indicated slight changes in annexin A6, Rap1 GTPase, and glyoxalase domain containing four spots while most of the main components did not show significant changes. By imaging MS analysis based on principal component analysis (PCA), we could find numerous alterations in the KO mouse brain. Furthermore, we could also know the information on the position of altered substances all together. PCA provides information about which molecules in tissue microdomains have altered and is helpful in analyzing large dataset of imaging MS, while exact identification of each molecule from peaks in MALDI imaging MS may require additional analyses such as MS/MS. Direct imaging with PCA is a powerful tool to perform in situ proteomics and will lead to novel findings. Our study shows that imaging MS yields information complementary to conventional 2‐DE analysis.
Mechanism of 3,4‐methylenedioxymethamphetamine (MDMA, ecstasy)‐mediated mitochondrial dysfunction in rat liver
Authors: Moon Kwan‐Hoon , Upreti Vijay V. , Yu Li‐Rong , Lee Insong J. , Ye Xiaoying , Eddington Natalie D. , Veenstra Timothy D. , Song Byoung‐Joon 
Published: September 2008

AbstractDespite numerous reports citing the acute hepatotoxicity caused by 3,4‐methylenedioxymethamphetamine (MDMA) (ecstasy), the underlying mechanism of organ damage is poorly understood. We hypothesized that key mitochondrial proteins are oxidatively modified and inactivated in MDMA‐exposed tissues. The aim of this study was to identify and investigate the mechanism of inactivation of oxidatively modified mitochondrial proteins, prior to the extensive mitochondrial dysfunction and liver damage following MDMA exposure. MDMA‐treated rats showed abnormal liver histology with significant elevation in plasma transaminases, nitric oxide synthase, and the level of hydrogen peroxide. Oxidatively modified mitochondrial proteins in control and MDMA‐exposed rats were labeled with biotin‐N‐maleimide (biotin‐NM) as a sensitive probe for oxidized proteins, purified with streptavidin–agarose, and resolved using 2‐DE. Comparative 2‐DE analysis of biotin‐NM‐labeled proteins revealed markedly increased levels of oxidatively modified proteins following MDMA exposure. Mass spectrometric analysis identified oxidatively modified mitochondrial proteins involved in energy supply, fat metabolism, antioxidant defense, and chaperone activities. Among these, the activities of mitochondrial aldehyde dehydrogenase, 3‐ketoacyl‐CoA thiolases, and ATP synthase were significantly inhibited following MDMA exposure. Our data show for the first time that MDMA causes the oxidative inactivation of key mitochondrial enzymes which most likely contributes to mitochondrial dysfunction and subsequent liver damage in MDMA‐exposed animals.