bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Initial High Shearing on Electrical and Rheological Properties and Formation of Percolating Agglomerates for MWCNT/Epoxy Suspensions
Authors: Schulz Sonja Carolin , Schlutter Jana , Bauhofer Wolfgang 
Published: June 2010

AbstractWe report on shear‐induced nanotube agglomerate formation in low viscous multiwalled carbon nanotube/epoxy suspensions during steady shear rate step tests. A combined setup allows monitoring of the electrical, rheological, and optical properties of the system. High initial shearing was found to be necessary to achieve the insulator‐to‐conductor transition as well as low shear rate viscosity enhancement. Depending on the applied pre‐shear, conductivity improvement of about four orders of magnitude was observed. Different morphologies for shear‐induced agglomerates were detected before and after high shear. The critical minimal shear rate for the system was determined and a simple model using phase separation due to high shear forces is proposed.magnified image
Mesoporous Silica Supported Multiple Single‐Site Catalysts and Polyethylene Reactor Blends with Tailor‐Made Trimodal and Ultra‐Broad Molecular Weight Distributions
Authors: Kurek Alexander , Mark Stefan , Enders Markus , Kristen Marc O. , Mülhaupt Rolf 
Published: June 2010

AbstractA ternary blend of the bisiminopyridine chromium (III) (Cr‐1) with the bisiminopyridine iron (II) (Fe‐2) post‐metallocenes with the quinolylsilylcyclopentadienyl chromium (III) halfsandwich complex (Cr‐3) was supported on mesoporous silica to produce novel multiple single‐site catalysts and polyethylene reactor blends with tailor‐made molecular weight distributions (MWDs). The preferred cosupporting sequence of this ternary blend on MAO‐treated silica was Fe‐2 followed by Cr‐1 and Cr‐3. Cosupporting does not impair the single‐site nature of the blend components producing polyethylene fractions with $\overline M _{\rm w}$ = 104 g · mol−1 on Cr‐1, $\overline M _{\rm w}$ = 3 × 105 g · mol−1 on Fe‐2, and $\overline M _{\rm w}$ = 3 × 106 g · mol−1 on Cr‐3. As a function of the Fe‐2/Cr‐1/Cr‐2 mixing ratio it is possible to control the weight ratio of these three polyethylenes without affecting the individual average molecular weights and narrow polydispersities of the three polyethylene fractions. Tailor‐made polyethylene reactor blends with ultra‐broad MWD and polydispersities varying between 10 and 420 were obtained. When the molar ratio of Fe‐2/Cr‐1 was constant, the ultra‐high molecular polyethylene (UHMWPE, $\overline M _{\rm w}$ > 106 g · mol−1) content was varied between 8 and 16 wt.‐% as a function of the Cr‐3 content without impairing the blend ratio of the other two polyethylene fractions and without sacrificing melt processability. When the molar ratio Fe‐2/Cr‐3 was constant, it was possible to selectively increase the content of the low molecular weight fraction by additional cosupporting of Cr‐1. Due to the intimate mixing of low and ultra‐high molecular weight polyethylenes (UHMPEs) produced on cosupported single‐site catalysts a wide range of melt processable polyethylene reactor blends was obtained.magnified image
Supramolecular Aggregates of Water Soluble Dendritic Polyglycerol Architectures for the Solubilization of Hydrophobic Compounds
Authors: Kurniasih Indah N. , Liang Hua , Rabe Jürgen P. , Haag Rainer 
Published: June 2010

AbstractDendritic core–shell architectures which are based on hyperbranched polyglycerol for the solubilization of hydrophobic drugs have been synthesized and characterized. The core of hyperbranched polyglycerol has been modified with hydrophobic biphenyl groups or perfluorinated chains to increase the core hydrophobicity of the macromolecules. These amphiphilic core–shell type architectures were then used to solubilize pyrene, nile red, and a perfluoro tagged diazo dye, as well as the drug nimodipine in water. Specific host–guest interactions such as fluorous–fluorous interactions could be tailored by this flexible core design and determined by UV spectroscopy. The transport capacity increased 450‐fold for nile red, 47‐fold for nimodipine, and 37‐fold for pyrene at a polymer concentration of only 0.1 wt.‐%. Surface tension measurements and scanning force microscopy (SFM) were used to reveal the aggregation properties of these complexes. The formation of supramolecular aggregates with diameters of ≈20 nm and critical aggregate concentrations of 2 × 10−6 mol · L−1 have been observed. This indicates the controlled self‐assembly of the presented amphiphilic dendritic core–shell type architectures.magnified image
Discrete Metal Catalysts for Stereoselective Ring‐Opening Polymerization of Chiral Racemic β‐Lactones
Authors: Carpentier Jean‐François 
Published: June 2010

AbstractPoly(β‐hydroxyalkanoate)s (PHAs) are a class of aliphatic polyesters that can be efficiently synthesized by ring‐opening polymerization (ROP) of β‐lactones. The case of chiral racemic β‐substituted β‐lactones is particularly appealing since these monomers open the way to original tacticities and materials different from those biotechnologically produced. In this overview, after briefly surveying general considerations associated to the ROP of β‐lactones and metal‐based catalysts used in stereoselective ROP of racemic β‐butyrolactone, special emphasis is given to discrete rare earth catalysts that have allowed the preparation of highly syndiotactic poly(3‐hydroxybutyrate)s. Recent developments – such as preparation of stereocontrolled PHAs with pendant structural groups via (co)polymerization of functional β‐substituted β‐lactones, and highly alternating copolymers obtained by ROP of mixtures of enantiomerically pure but different monomers – are also discussed.magnified image
Assembly of Anionic Conjugated Polymer with 6‐O‐Modified PNP‐β‐Galactoside for Fluorescence Logic‐signal‐based Multiplex Detections of Enzymes
Authors: Wang Ya‐juan , Xin Bao‐juan , Duan Xin‐rui , Xing Guo‐wen , Wang Shu 
Published: June 2010

AbstractAnionic conjugated polymer (PFP‐SO) was assembled with a novel enzymatic substrate 6‐O‐modified PNP‐β‐galactoside (1) for sensitive multiplex enzyme detections. The PFP‐SO/1/lipase/β‐galactosidase system has two chemical input signals which are Input 1 (lipase) and Input 2 (β‐galactosidase), and output optical signals such as fluorescence emission at 416 nm or 450 nm. Four types of logic gates, including YES, INH, NAND and AND, were successfully constructed and utilized for multiplex detections of lipase and β‐galactosidase in one tube.magnified image
Functional polymorphisms in cell death pathway genes and risk of renal cell carcinoma
Authors: Zhu Jian , Qin Chao , Wang Meilin , Yan Fu , Ju Xiaobing , Meng Xiaoxin , Ding Qi , Li Pu , Yang Jian , Cao Qiang , Zhang Zhengdong , Yin Changjun 
Published: June 2010

AbstractThe FAS/FAS ligand (FASL) system plays a key role in regulating apoptotic cell death, and corruption of this signaling pathway has been shown to participate in tumorigenesis. However, the effects of functional promoter polymorphisms of the CASP8, FAS, and FASL genes on risk of renal cell carcinoma (RCC) are unknown. In this study, we genotyped CASP8 ‐652 6N ins/del, FAS ‐1377 G > A, FAS ‐670 A > G, and FASL ‐844 C > T polymorphisms in a hospital‐based case–control study of 353 patients diagnosed with RCC and 365 cancer‐free controls in a Chinese population. Compared with CASP8 ‐652 ins/ins genotype, the del/del genotype had a significantly decreased RCC risk [adjusted odds ratio (OR) = 0.36, 95% confidence interval (CI) = 0.16–0.84]. For FAS ‐1377 G > A polymorphism, a significantly increased risk of RCC was found for AA (adjusted OR = 1.65, 95% CI = 1.03–2.64) and GA (adjusted OR = 1.41, 95% CI = 1.02–1.94) genotypes compared with GG genotype. When we combined these two polymorphisms together, we found that individuals carrying CASP8 ‐652 6N ins/del and FAS ‐1377 GG genotypes or CASP8 ‐652 6N del/del and FAS ‐1377 GG genotypes were associated with a statistically significantly decreased risk of RCC (adjusted OR = 0.46, 95% CI = 0.24–0.88 and OR = 0.12, 95% CI = 0.02–0.58, respectively) compared with individuals carrying CASP8 ‐652 6N ins/ins and FAS ‐1377 AA genotypes. These results suggest that the CASP8 ‐652 6N ins/del and FAS ‐1377 G > A polymorphisms are involved in the susceptibility to developing RCC in Chinese populations. © 2010 Wiley‐Liss, Inc.
Spiralometry: Computerized assessment of tremor amplitude on the basis of spiral drawing
Authors: Kraus Peter H. , Hoffmann Arndt 
Published: June 2010

AbstractSpiral drawing has been used for the assessment of the impact of therapy on motor performance in various movement disorders (e.g. in Parkinson's disease, especially for tremor and hypokinesia). Nevertheless, there are only few guidelines available providing some kind of standardized interpretation. The published protocol with the highest standard is that of Bain and Findley. Kinetic tremor assessed by spiral drawing is not quantified by alternative approaches so far and is not even considered by most rating scales. However, kinetic tremor is quite common and represents a significant impairment in the everyday life of parkinsonian patients. More complex instrumental methods for the quantification of kinetic tremor have not been practical as they, e.g., require relatively expensive equipment or have an unfavourable effort/benefit ratio. We pursued an alternative approach, where we scan drawn spirals to a computer‐algorithm that calculates the tremor amplitude. Our standardized method can be applied without difficulty in patients needing only paper and pencil. The evaluation is fully automated, and therefore, it is appropriate for the assessment of therapeutic efficacy in very large populations. The objectivity of the approach represents a significant advantage. In the actual paper, we present how we analyzed the original spirals published by Bain and Findley to validate our computerized assessment. We found a highly significant connection between both methods (explained variance: 88.9%). © 2010 Movement Disorder Society
The Integrated Deconvolution Estimation Model: A Parameter Estimation Method for Ethylene/α‐Olefin Copolymers Made with Multiple‐Site Catalysts
Authors: Al‐Saleh Mohammad A. , Soares João B. P. , Duever Thomas A. 
Published: June 2010

AbstractThe integrated deconvolution estimation model (IDEM) to estimate the microstructural parameters of polyolefins made with multiple‐site catalysts is described. IDEM estimates ethylene/α‐olefin reactivity ratios for each site type in two‐steps. In the first step, the MWD of the whole copolymer is deconvoluted into several Flory's most probable distributions, to determine the number of site types and the weight fraction of copolymer made on each of them. In the second estimation step, the model deconvolutes the CSLD of the copolymer into its individual components per site type, and estimates their respective reactivity ratios. This is the first time that MWD and CSLD information is integrated to estimate the reactivity ratios of polyolefins made with multiple‐site catalysts.magnified image
Imaging three‐dimensional myocardial mechanics using navigator‐gated volumetric spiral cine DENSE MRI
Authors: Zhong Xiaodong , Spottiswoode Bruce S. , Meyer Craig H. , Kramer Christopher M. , Epstein Frederick H. 
Published: June 2010

AbstractA navigator‐gated 3D spiral cine displacement encoding with stimulated echoes (DENSE) pulse sequence for imaging 3D myocardial mechanics was developed. In addition, previously described 2D postprocessing algorithms including phase unwrapping, tissue tracking, and strain tensor calculation for the left ventricle (LV) were extended to 3D. These 3D methods were evaluated in five healthy volunteers, using 2D cine DENSE and historical 3D myocardial tagging as reference standards. With an average scan time of 20.5 ± 5.7 min, 3D data sets with a matrix size of 128 × 128 × 22, voxel size of 2.8 × 2.8 × 5.0 mm3, and temporal resolution of 32 msec were obtained with displacement encoding in three orthogonal directions. Mean values for end‐systolic mid‐ventricular mid‐wall radial, circumferential, and longitudinal strain were 0.33 ± 0.10, −0.17 ± 0.02, and −0.16 ± 0.02, respectively. Transmural strain gradients were detected in the radial and circumferential directions, reflecting high spatial resolution. Good agreement by linear correlation and Bland‐Altman analysis was achieved when comparing normal strains measured by 2D and 3D cine DENSE. Also, the 3D strains, twist, and torsion results obtained by 3D cine DENSE were in good agreement with historical values measured by 3D myocardial tagging. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
An optimized 3D spoiled gradient recalled echo pulse sequence for hemorrhage assessment using inversion recovery and multiple echoes (3D SHINE) for carotid plaque imaging
Authors: Zhu David C. , Vu Anthony T. , Ota Hideki , DeMarco J. Kevin 
Published: June 2010

AbstractIntraplaque hemorrhage into the carotid atherosclerotic plaque has been shown to create instability and progression. We have developed an optimized 3D Spoiled Gradient recalled echo pulse sequence for Hemorrhage assessment using INversion recovery and multiple Echoes (3D SHINE) for carotid plaque imaging. The sequence was developed by incorporating multiecho acquisition to its clinically validated optimized single‐echo counterpart 3D inversion recovery prepared fast spoiled gradient recalled sequence. With similar scan time (4 min), 3D spoiled gradient recalled echo pulse sequence for hemorrhage assessment using inversion recovery and multiple echoes maintained comparable high‐resolution volumetric coverage, black‐blood effect, contrast, signal‐to‐noise and contrast‐to‐noise ratios, and similar sensitivity and specificity in detecting whether intraplaque hemorrhage was present on an artery. The multiple echoes acquired with 3D SHINE allowed the estimation of intraplaque hemorrhage T*2 and then the subsequent characterization of intraplaque hemorrhage (T*2 for type I < 14 msec, and for type II > 14 msec). The type I intraplaque hemorrhage size estimated by 3D SHINE was significantly and positively correlated with the size estimated manually by an expert reviewer using the histology‐validated multicontrast MRI technique (r = 0.836 ± 0.080, p < 0.001). With only one fast sequence, 3D SHINE can detect and characterize intraplaque hemorrhage that has previously required a multicontrast approach using a combination of black‐blood T1‐weighted, black‐blood T2‐weighted, and time‐of‐flight imaging techniques. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Deflated preconditioned conjugate gradient solvers for the pressure‐Poisson equation: Extensions and improvements
Authors: Löhner Rainald , Mut Fernando , Cebral Juan Raul , Aubry Romain , Houzeaux Guillaume 
Published: June 2010

AbstractExtensions and improvements to a deflated preconditioned conjugate gradient technique for the solution of the pressure‐Poisson equation within an incompressible flow solver are described. In particular, the use of the technique for embedded grids, for cases where volume of fluid or level set schemes are required and its implementation on parallel machines are considered. Several examples are included that demonstrate a considerable reduction in the number of iterations and a remarkable insensitivity to the number of groups/ regions chosen and/or to the way the groups are formed. Copyright © 2010 John Wiley & Sons, Ltd.
A discrete mechanics approach to the Cosserat rod theory—Part 1: static equilibria
Authors: Jung Pascal , Leyendecker Sigrid , Linn Joachim , Ortiz Michael 
Published: June 2010

AbstractA theory of discrete Cosserat rods is formulated in the language of discrete Lagrangian mechanics. By exploiting Kirchhoff's kinetic analogy, the potential energy density of a rod is a function on the tangent bundle of the configuration manifold and thus formally corresponds to the Lagrangian function of a dynamical system. The equilibrium equations are derived from a variational principle using a formulation that involves null‐space matrices. In this formulation, no Lagrange multipliers are necessary to enforce orthonormality of the directors. Noether's theorem relates first integrals of the equilibrium equations to Lie group actions on the configuration bundle, so‐called symmetries. The symmetries relevant for rod mechanics are frame‐indifference, isotropy, and uniformity. We show that a completely analogous and self‐contained theory of discrete rods can be formulated in which the arc‐length is a discrete variable ab initio. In this formulation, the potential energy density is defined directly on pairs of points along the arc‐length of the rod, in analogy to Veselov's discrete reformulation of Lagrangian mechanics. A discrete version of Noether's theorem then identifies exact first integrals of the discrete equilibrium equations. These exact conservation properties confer the discrete solutions accuracy and robustness, as demonstrated by selected examples of application. Copyright © 2010 John Wiley & Sons, Ltd.
Variation in health and socioeconomic status within the W. Montague Cobb skeletal collection: Degenerative joint disease, trauma and cause of death
Authors: Watkins R. 
Published: June 2010

AbstractThis paper examines health differences between two distinct samples within an African American skeletal population by investigating variation in osteoarthritis (OA) patterns, the presence of enthesopathies, fractures and cause of death. Surveys and statistical treatments tested the hypothesis that two samples within a population that have different socioeconomic contexts will present associated differences in health.Binomial statistics were used to examine differences in OA patterns and prevalence within and between groups, and according to age and sex. These data were paired with information on the presence of enthesopathies at select muscle attachment and insertion sites to add another dimension to the assessment of mechanical strain. Finally causes of death, when available, were recorded to compare leading causes within and between samples, as well as with the larger population.Data reveal significant differences in the prevalence of OA between groups. Significant differences also presented when comparing the prevalence of unilateral and bilateral affect. Although a number of differences in health status observed can be attributed to age, relationships between the presence of OA and enthesopathies in a portion of the sample indicates that degenerative change and hypertrophy in the samples reflect both systemic and non‐systemic change. The presence and pattern of fractures and causes of death are also suggestive of differences in social context between the two samples. Copyright © 2010 John Wiley & Sons, Ltd.
Time‐delay dependentH∞model simplification for singular systems with Markovian jumping parameters
Authors: Lu Hongqian , Zhou Wuneng , Xu Yuhua , Fang Jian'an , Tong Dongbing 
Published: June 2010

AbstractThe problem ofH∞model simplification for singular systems with Markovian jumping parameters and time‐delay is investigated. For a given stochastic stable system, our attention is focused on the construction of reduced‐order models which guarantee the corresponding error system to be admissible and have a prescribedH∞error performance. A robust admissibility condition and a robust bounded real lemma are developed based on which, sufficient conditions for the existence of desired reduced‐order models are proposed. Desired reduced‐order model can be constructed when the proposed conditions are satisfied. The effectiveness of the proposed model reduction method is illustrated via a numerical example. Copyright © 2010 John Wiley & Sons, Ltd.
Selected experimental methods for determining droplet parameters from the intensity distribution of scattered light: A review
Authors: Roth N. , Weigand B. 
Published: June 2010

AbstractThe present paper summarizes some experimental methods, which have been developed using the results of calculations based on the theory of Gustav Mie. As examples two regions of the scattered light are considered in more detail. The intensity distribution in the forward hemisphere for scattering angles 30 ≤ θ ≤ 60 shows maxima, which can be identified as regular fringes on a screen. The spacing between the fringes is a measure for the droplet size.In the intensity distribution of the backward hemisphere the region of the first rainbow can be found. In the rainbow region a main maximum, subsidiary maxima and a ripple structure can be identified. The angular position of the main maximum is a measure for the refractive index of the droplet. The angular distance between the subsidiary maxima and the angular distance between the ripples both are a function of droplet size. A comparison with other size measurement methods gives information about the sphericity of the droplet.An evaporating droplet shows for instance oscillations of the rainbow position due to morphology dependent resonances. The oscillation frequency is proportional to the evaporation rate.
Parameter Identification of a Finite Viscoplastic Material Model using different Deterministic Optimization Methods
Authors: Rieger A. , Scheday G. , Miehe C. 
Published: June 2010

AbstractThe efficiency of two deterministic optimization strategies are discussed in order to solve the arising least squares minimization problem. A sequential quadratic programming method is compared with a trust region enhanced simplex method. In particular we focus on the effort to determine the necessary gradients for the sqp‐method and compare the computational costs of the identification process. In the later development the identification problem is extended to account for inhomogeneous deformations using the finite element method for simulation purpose. Here, displacement fields are determined via an optical measurement technique. The accompanying modification of the solution procedure results in an extended least squares functional. The sensitivity analysis, needed for the gradient based method, is embedded in a distinct format in the finite element context.
Cross‐coupling and Unbalance Compensation of a Rigid Rotor
Authors: Hirschmanner Martin 
Published: June 2010

AbstractThe system under investigation is a rigid rotor supported by two active magnetic bearings. In this paper two coexisting sources of vibrations are considered. First, mass unbalance excitation as a synchronous periodic disturbance and second, destabilizing cross‐coupling forces as generated, for example, by fluid film mechanisms, annular pressure seals or labyrinths of a turbo machine. The basic AMB‐control is carried out by a simple PID controller while for the compensation of both excitation mechanisms two independent control algorithms are used. In order to compensate the destabilizing cross‐coupling forces a least square estimator estimates the unknown parameters of the cross‐coupling mechanism. The mass unbalance forces are compensated by a recursive gain scheduled algorithm. By combining these two algorithms a significant reduction of the vibration level is achieved.
An approach to the modelling of worm‐like motion systems with finite degree of freedom – First steps in technical realization
Authors: Zimmermann K. , Zeidis I. , Jianjun Huang , Steigenberger J. 
Published: June 2010

AbstractThe paper presents some investigations of worm‐like motion systems that have the earthworm as live prototype. The systems are modeled in form of straight chains of n interconnected mass points. The ground contact can be described by non‐symmetric dry friction. Analytical solutions using asymptotical methods are presented.
Phasebehaviour of a 3D–Stell–Hemmer Liquid
Authors: Mausbach P. , May H.‐O. 
Published: June 2010

AbstractInvestigations for one– and two–dimensional systems have shown that the Stell–Hemmer potential can produce liquid–state anomalies. By means of a Monte Carlo simulation for a N; V; T–ensemble we calculate the phase behaviour and show that these anomalies disappear in three dimensions.