bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tribological Performance of Polyetheretherketone and its Composites under Water Environment
Authors: Mimaroglu A. , Unal H. , Ozel A. 
Published: May 2013

SummaryIn this study, the influence of lubrication on the friction and wear performance of pure polyetheretherketone (PEEK), 30 wt.‐% carbon fiber and 30 wt.‐% glass fibers reinforced PEEK composite is investigated. The sliding experiments were carried out on a polymer pin‐on‐ a steel disc arrangement. Wear tests were resumed at room temperature under 50 to 200N loads and at 0.40 and 1.2 m/s sliding speed. The results show the large influence of water lubricant on the tribological performance of PEEK and PEEK composites. Furthermore, the coefficient of friction for PEEK increases by the increase in applied load value but this influence is not significant for PEEK composites. Generally, for the range of load and speed values for this study, the coefficient of friction using water lubricant registered lower values than that of the dry condition. Finally, the specific wear rates for PEEK + 30 wt%CF and PEEK + 30 wt%GFR composite under water lubricated conditions are all mostly in the order of 10−15 m2/N.
Depth Profiling of Block Copolymer Nanostructures in Films by Small‐Angle X‐Ray Scattering Using an X‐Ray Microbeam
Authors: Sakurai Shinichi , Kimura Go , Mizuno Yohei , Masunaga Hiroyasu , Ogawa Hiroki , Ohta Noboru , Yagi Naoto 
Published: May 2013

SummaryWe applied the microbeam two‐dimensional small‐angle X‐ray scattering (2d‐µSAXS) technique in order to characterize orientation of polystyrene (PS) microdomains as a function of the distance from the free surface of a sample sheet down to the surface facing to the substrate, for depth profiling for spontaneous perpendicular orientation of PS cylinders in the matrix of polyethylenebutylene (PEB) in a PS‐b‐PEB‐b‐PS triblock copolymer thick sheet as thick as ∼0.5 mm. It has been revealed that near the free surface the cylinders were randomly oriented down to ∼70 µm in depth. Although this might indicate that the surface effect, which preferentially dictates cylinders to be oriented parallel to the surface, can propagate for such a long distance, 70 µm is unusually huge as compared to the general knowledge of the surface effect propagating at most for 1 µm. Experimentally examining further, we finally conclude that the 2d‐µSAXS depth profiling overestimates the surface effect. This unfavorable conclusion may be ascribed to surface roughness of the sample sheet subjected to the measurement, and in order to obtain a good result a big effort is required to prepare the surface as flat as possible.
Structural Relaxations in Liquid Crystalline Formation and Glass Transition for Comb‐Like Polymer: Activation Energy Spectrum Analysis
Authors: Tanaka Yutaka , Yukimoto Yosuke 
Published: May 2013

SummaryThis study demonstrates that the modelling approach for the kinetic phenomenon of glass transition is effective to examine the relaxation. In the enthalpy relaxation of poly(cyanobiphenyl‐yloxy) alkyl acrylate, the decrease in enthalpy was measured as a function of ageing time and ageing temperature. Obtained data was analysed at first with the activation energy spectrum (AES) model, and next, with the framework of the entropy model which follows the evolution of the configurational entropy of the sample during the whole thermal history in the experiment. The prediction of DSC curve based on the analysis for the glass transition is presented. AES model gives information about thermally activated processes which are available to contribute to observed enthalpy changes against the thermal history. The activated processes are relevant to the rearrangement of the polymer chain. The effect of molecular weight on the peak maximum appeared in AES is reported.
Stress concentrations in periodic notches: a critical investigation of Neuber's method
Authors: Castagnetti D. , Dragoni E. 
Published: May 2013

AbstractThe work investigates the stress concentrations produced by periodic notches (i. e. uniformly repeated) in elastic solids under different loading conditions. Neuber's criterion, which likens the effect of a periodic notch to a single notch of similar profile but lesser depth, is critically examined. The criterion simply correlates the depth reduction factor to the ratio between the depth and the pitch of the original periodic notch, regardless of its shape. By examining literature results in periodic notches on circular bars and plane strips under torsion or axial loads, the work proves the accuracy of the Neuber's method for the ideal configuration of a sharp and shallow notch under shear stresses. By contrast, for real notches with a large root radius and finite depth, the accuracy is very poor, in particular for normal stresses. However, it is found that by simply ‘repairing’ the expression of the depth reduction factor and distinguishing between notches under shear or normal stresses, the criterion provides very accurate results, and becomes quite useful for real geometries.
Prediction of dynamic stiffness on rubber components considering preloads
Authors: Lee Y. H. , Kim J‐s , Kim K. J. , Ahn T. , Choi B‐I , Lee H. J. , Woo C.‐S. , Kim K.‐S. 
Published: May 2013

AbstractNowadays rubber is used as various parts of vehicles to improve the noise, vibration and harshness (NVH) performance. Usually computer aided engineering (CAE) is commonly used to analyze various characteristics of vehicles. However, it is quite difficult to analyze the noise, vibration and harshness characteristics of an entire vehicle which includes lots of rubber components. There are two reasons. One is that the relation between load and deformation of rubber shows non‐linear behavior. Another is that the preload is already acting on rubber components of complex shape when in assembly. Therefore repetitive tests are needed to clarify the dynamic characteristics of rubber components when preload works. It needs considerable time and effort if the shape of rubber components is changed to a large number of times in the development stages. In the present study, an efficient experimental method is suggested, which estimates the dynamic stiffness of a rubber component under various preload condition using the static and dynamic stiffness of the rubber material specimen and the static stiffness of the rubber component. It is assumed that the dynamic ratio – at any frequency, the ratio of the dynamic stiffness to the static stiffness of rubber – is constant at any frequency. The dynamic ratio is calculated due to the static and dynamic stiffness of the rubber material specimen that can be easily obtained from experimental tests. Then, the dynamic stiffness of a rubber component under any preload can be estimated by multiplying the dynamic ratio by the instantaneous static stiffness of the rubber component under the preload. In conservative approach, the dynamic stiffness of rubber is calculated by simply doing a multiplication of the static stiffness of rubber by 1.2~1.5 without consideration of the preload, due to difficulties of repetitive tests. Therefore, it is suggested that the dynamic stiffness of a rubber component can be precisely predicted in various preload conditions through only a few numbers of tests.
Analyses of self‐focusing phenomenon and temperature rise in light absorption medium by ultrashort pulse laser irradiation
Authors: Ohmura E. 
Published: May 2013

AbstractIn this study, a paraxial wave equation including light absorption term was solved by numerical calculation using the fast Fourier transform for irradiation of a Kerr medium irradiated by an ultrashort pulse laser. Using the absorbed energy distribution as the initial condition, heat transfer analysis in the material was conducted. The influences of the nonlinear index intensity coefficient and the absorption coefficient on the temperature distribution in the material were investigated.
On the numerical simulation of laser beam cutting of hollow sphere structures
Authors: Araújo M. , Merkel M. , Riegel H. , Öchsner A. 
Published: May 2013

AbstractLaser beam cutting is a highly efficient technique to cut materials. The relatively small amount of energy being involved during the process results in a small heat affected zone. This characteristic makes laser beam cutting interesting for composite materials. Within this paper the cutting process is applied to metallic hollow sphere structures (MHSS), a relatively new group of advanced composite materials. The metallic hollow sphere structures combine the well‐known advantages of cellular metals without major scattering of their material parameters. They are characterised by high geometry reproduction leading to relatively constant mechanical and physical properties. Numerical simulation is used in order to define proper process parameters for a large variety of metallic hollow sphere structures. The finite element method based simulation covers material parameters as well as process parameters like the cutting velocity. Heat conduction, convection and heat radiation is taken into account. The temperature distribution is our fundamental result. It should be mentioned that phase change from solid to liquid state is also included in the computational procedure.
On the accuracy of finite difference schemes for beam problems in the elastic range
Authors: Davoudi M.M. , Öchsner A. 
Published: May 2013

AbstractThe finite difference method is applied to derive approximate solutions for the bending line of Euler‐Bernoulli beam problems. The investigations are restricted to simple static configurations, i. e. straight beams with constant symmetrical cross‐sections and constant elastic material properties. Only finite difference schemes of second‐order accuracy are considered and special emphasis is given to the implementation of the boundary conditions. Based on comparisons with the exact solutions, clear recommendations can be given on the required number of nodes to obtain a certain accuracy in the numerical approach.
Angle‐sensitive MRI for quantitative analysis of fiber‐network deformations in compressed cartilage
Authors: Garnov Nikita , Busse Harald , Gründer Wilfried 
Published: May 2013

AbstractPurposeTo demonstrate the feasibility of a novel experimental method to quantitatively analyze fiber‐network deformation in compressed cartilage by angle‐sensitive magnetic resonance imaging (MRI) of cartilage.MethodsThree knee cartilage samples of an adult sheep were imaged in a high‐resolution MRI scanner at 7 T. Main fiber orientation and its “offset” from the direction perpendicular to the bone‐cartilage boundary were derived from MR images taken at different orientations with respect to B0. Bending of the collagen fibers was determined from weight‐bearing MRI with the load (up to 1.0 MPa) applied over the whole sample surface. A “fascicle” model of the cartilage ultrastructure was assumed to analyze characteristic intensity variations in T2‐weighted images under load.ResultsT2‐weighted MR images showed a strong variation of the signal intensities with sample orientation. In the T2‐weighted weight‐bearing series, regions of high signal intensity underwent shifts from the lateral to the central parts in all three cartilage samples. The bending of the collagen fibers was determined to be 27.2°, 35.4°, and 40.0° per MPa, respectively.ConclusionAssuming a “fascicle” model, the presented MRI method provides quantitative measures of structural adjustments in compressed cartilage. Our preliminary analysis suggests that cartilage fiber deformation includes both bending and crimping.
Immigrant assimilation and BMI and waist size: A longitudinal examination among hispanic and chinese participants in the multi‐ethnic study of atherosclerosis
Authors: Albrecht Sandra S. , Roux Ana V. Diez , Kandula Namratha R. , Osypuk Theresa L. , Ni Hanyu , Shrager Sandi 
Published: May 2013

ObjectiveUS birth and longer length of US residence among the foreign‐born have been linked to higher anthropometric measures. However, previous studies have been cross sectional and few have examined heterogeneity by ethnic group. Cross‐sectional findings that show immigrant weight converging to US‐born levels with longer time in the United States imply that immigrants' weight is increasing at a faster rate relative to US‐born individuals. Prospective studies are necessary to confirm this pattern.Design and MethodsUsing longitudinal data from 1,486 Hispanic and 802 Chinese adults aged 45‐84 years in the Multi‐ethnic Study of Atherosclerosis, we examined whether foreign‐born participants experienced greater increases in BMI and waist circumference (WC) than the US‐born over a median follow‐up of 5 years. We also investigated heterogeneity in these associations by Hispanic subgroup.ResultsAmong Hispanics and Chinese, the foreign‐born had a lower adjusted mean BMI and WC at baseline than the US‐born, but there were no significant differences in BMI or WC change over time. There was heterogeneity by Hispanic subgroup: despite small baseline nativity differences in WC, foreign‐born Mexican Hispanics had a greater annual mean increase in WC over time compared to US‐born Mexican Hispanics (mean difference in annual change = 0.28 cm, P = 0.03). There were no nativity differences in the rate of WC increase over time among non‐Mexican Hispanics. Foreign‐born Mexican Hispanics also experienced a faster rate of WC increase compared to foreign‐born non‐Mexican Hispanics (mean difference in annual change = 0.24 cm, P = 0.01).ConclusionsLonger time in the United States, examined prospectively, may only be linked to adverse anthropometric changes in some immigrant groups.
Longitudinal measurement of fetal thigh soft tissue parameters and its role in the prediction of birth weight
Authors: O'Connor Clare , Farah Nadine , O'Higgins Amy , Segurado Ricardo , Fitzpatrick Chris , Turner Michael J. , Stuart Bernard , Kennelly Máireád M. 
Published: May 2013

ABSTRACTObjectiveThe aim of this study was to profile longitudinal changes in thigh muscle and fat with gestation and to determine whether thigh measurements can improve the prediction of birth weight (BW).MethodsA prospective longitudinal study of subcutaneous soft tissue measurements was conducted in 328 singleton fetuses at 28 and 37 weeks gestation. Estimated fetal weight (EFW) was calculated using abdominal circumference, femur length, biparietal diameter, and head circumference.ResultsThe fetal abdominal subcutaneous tissue (FAST) and thigh muscle and fat show an increase with gestation. At 28 weeks gestation, the abdominal circumference, thigh fat, FAST, and EFW percentile were found to be significant predictors of BW. A combination of EFW percentile and thigh fat were found to be the optimal multivariate model at 28 weeks for predicting BW. At 37 weeks, BW prediction using EFW percentile, FAST, and thigh fat was the most accurate. The results revealed acceptable reproducibility for fetal thigh muscle and fat.ConclusionThis study provides reference ranges for thigh fat and muscle at 28 and 37 weeks gestation. The inclusion of fetal thigh fat in the algorithm improves the predictive power for birth weight. This information is important to explore the role of fetal thigh in the detection of aberrant growth. © 2013 John Wiley & Sons, Ltd.
Hexamethylenetetramine Dinitrate (HDN): The Precursor for RDX Production by Bachmann Process
Authors: Turhan Hamza , Atalar Taner , Erdem Nilüfer , Özden Canpolat , Din Bahaddin , Gül Nebi , Yildiz Emel , Türker Lemi 
Published: May 2013

AbstractHexamethylenetetramine dinitrate (HDN) is a rather weak explosive but is used as a precursor for the synthesis of RDX, one of the most important secondary nitramine explosives. HDN has limited application because of its hygroscopic character. This paper reports on the synthesis and characterization of HDN in high yield and purity by the reaction of hexamine with nitric acid at temperatures below 15 °C. It was characterized by FTIR and 1H NMR spectroscopy, Scanning Electron Microscopy (SEM) and Liquid Chromatography/Mass Spectrometry (LC/MS) measurements. The thermal characteristics of HDN were determined by DSC and TG/DTA. The DSC curve of HDN shows an endothermic peak at 170.5 °C corresponding to the melting point of HDN, followed by two exothermic peaks at 174.0 °C and 200.5 °C due to the decomposition. The differences in the thermal behavior of HDN samples, which were thermally aged at 50 °C, 100 °C, and 150 °C in a nitrogen atmosphere were examined. Additionally, some quantum chemical properties of the nitration of hexamethylenetetramine were calculated.
An exemplar‐based learning approach for detection and classification of malicious network streams in honeynets
Authors: Abbasi Fahim H. , Harris Richard , Marsland Stephen , Moretti Giovanni 
Published: May 2013

ABSTRACTVariants of malware and exploits are emerging globally at an ever‐increasing rate. There is a need to automate their detection by observing their footprints over network streams, but signature‐based intrusion detection systems alone cannot cope with the dynamic nature of modern security threats. In this paper, we approach intrusion detection as a classification problem and describe a system using exemplar‐based learning to correctly classify known classes of malware and to detect, learn and classify unknown malicious streams into classes. Copyright © 2013 John Wiley & Sons, Ltd.
Strategies of network coding against nodes conspiracy attack
Authors: Du Rong , Zhao Chenglin , Zhao Feng , Li Shenghong 
Published: May 2013

AbstractNetwork coding has emerged some exciting future because of its smart technology in wireless sensor networks. At the same time, it is facing security attacks, especially conspiracy Attack. Most existing security strategies are concentrated on coding design, there has been almost no consideration from topological structure. In this background, a weakly‐secure scheme is proposed from the perspective of topology. Considering the performance of this scheme, an advanced scheme is put forward later. Simulations show that the two strategies can prevent cooperative eavesdroppers from acquiring any useful information transmitted from source node to sink node and the performance of advanced scheme is better. Copyright © 2013 John Wiley & Sons, Ltd.
Towards pattern‐based architectures for event processing systems
Authors: Bruns Ralf , Dunkel Jürgen 
Published: May 2013

SUMMARYRecently, event processing (EP) has gained considerable attention as an individual discipline in computer science. From a software engineering perspective, EP systems still lack the maturity of well‐established software architectures. For the development of industrial EP systems, generally accepted software architectures based on proven design patterns and principles are still missing. In this article, we introduce a catalog of design patterns that supports the development of event‐driven architectures (EDAs) and complex EP systems. The design principles originate from experiences reported in publications as well as from our own experiences in building EP systems with industrial and academic partners. We present several patterns on different layers of abstractions that define the overall structure as well as the building blocks for EP systems. Architectural patterns that determine the top‐level structure of an EDA can be distinguished from design patterns that specify the basic mechanisms of EP. The practical application of the catalog of patterns is described by the pattern‐based design of a sample EDA for a sensor‐based energy control system. Finally, we propose a coherent and general reference architecture for EP derived from the proposed patterns.Copyright © 2013 John Wiley & Sons, Ltd.
Electrochemical and Biological Studies on Reactivity of [VO(oda)(H2O)2], [Co(oda)(H2O)2]·H2O, and [Ni(oda)­(H2O)3]·1.5H2O Towards Superoxide Free Radicals
Authors: Wyrzykowski Dariusz , Inkielewicz‐Stępniak Iwona , Czupryniak Justyna , Jacewicz Dagmara , Ossowski Tadeusz , Woźniak Michal , Chmurzyński Lech 
Published: May 2013

AbstractThe reactivity of superoxide free radicals (O2·–) generated electrochemically towards the oxydiacetate metal complexes, namely [VO(oda)(H2O)2], [Co(oda)(H2O)2]·H2O, and [Ni(oda)(H2O)3]·1.5H2O (oda = oxydiacetate) was examined by cyclic voltammetry. The measurements were carried out in DMSO solution using a platinum electrode. Based on the height of the anodic peak Ea that corresponds to electrochemical oxidation O2·– → O2 + e, in the absence and in the presence of the compounds in the mixture, their O2·– scavenge ability was assessed. The influence of the type of the complex was briefly discussed. H2O2 was used to induce cellular injury in a mouse hippocampal cell line (HT22). The cytoprotection of chemical compounds was tested at the mitochondrial (MTT test) and plasma membrane level (LDH leakage). Dose‐dependent effect (10 and 100 μM of the complex) of investigated compounds was observed.
Fetal growth restriction caused by MIMT1 deletion alters brain transcriptome in cattle
Authors: Venhoranta Heli , Bauersachs Stefan , Taponen Juhani , Lohi Hannes , Taira Tomi , Andersson Magnus , Kind Alexander , Schnieke Angelika , Flisikowski Krzysztof 
Published: May 2013

AbstractWe examined levels of gene expression in the brains of bovine fetuses carrying a truncated MIMT1 allele, MIMT1Del, shown to cause late abortion and stillbirth as a result of fetal growth restriction. MIMT1 is a non‐protein coding gene that forms part of the imprinted PEG3 (paternally expressed gene 3) domain. Microarray analysis of brain cortex samples from mid‐gestation MIMT1Del/WT bovine fetuses and wild‐type siblings was performed to study the effect of fetal growth restriction on brain gene expression. Statistical analysis revealed 134 genes with increased mRNA levels and 22 with reduced levels in MIMT1Del/WT fetuses. Gene set enrichment analysis identified a relatively small number of significant functional clusters representing three major biological processes: response to oxidative stress, angiogenesis, and epithelial cell proliferation. Gene expression microarray analyses identified increased expression of VIPR2, HTRA1, S100A4 and MYH8 in fetuses carrying the deletion and decreased expression of DRD2, ADAM18, miR345, ZNF585A. ADAM18, DRD2 and S100A4 are known to be involved in prenatal brain development. ZNF585A, miR‐345, VIPR2, HTRA1, and MYH8 are known to be involved in cell growth and differentiation, but any role in neural developmental has yet to be elucidated.
Urinary excretion of B-group vitamins reflects the nutritional status of B-group vitamins in rats
Authors: Shibata Katsumi , Sugita Chisa , Sano Mitsue , Fukuwatari Tsutomu 
Published: May 2013

AbstractWe have reported previously that the urinary excretion of B-group vitamins reflects recent dietary intakes of these vitamins. We also proposed reference values for the urinary levels of B-group vitamins for human subjects, and used these for evaluating human nutritional status. However, the question arises as to whether the urinary excretion of B-group vitamins in animals or human subjects decreases immediately before they become B-group vitamin insufficient or when fed a diet low in vitamins. In the present study, rats were fed a vitamin-free diet for 5 d, and changes in the levels of B-group vitamins in urine and blood were monitored. Urinary excretion of vitamin B1, vitamin B2, 4-pyridoxic acid (a catabolite of vitamin B6), pantothenic acid, folate and biotin steeply decreased, and all of the values reached zero within 1–2 d. With respect to blood, the concentrations of only three of the eight B-group vitamins (vitamin B1, pyridoxal phosphate and biotin) decreased to 15 % (P < 0·0001), 7 % (P < 0·0001) and 2 % (P < 0·0001) on day 5, respectively, compared with the values at the beginning of the experiment. The decrease was more rapid and the changes were greater in the urine samples than in the blood samples. The present data complement our previous proposal that the urinary excretion of B-group vitamins reflects the nutritional status of these vitamins.