bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computational Approaches for Studying the Granular Dynamics of Continuous Blending Processes, 1 – DEM Based Methods
Authors: Dubey Atul , Sarkar Avik , Ierapetritou Marianthi , Wassgren Carl R. , Muzzio Fernando J. 
Published: March 2011

AbstractComputational methods using mechanistic modeling with a specific application in the area of continuous blending are presented. These methods complement experimental designs and aim to reduce the amount of time, effort, and material required to characterize a device or a process. The discrete element method is applied to the specific case of continuous mixing using two approaches. The first approach models an entire blender and studies the impact of changing impeller speed on residence time distribution (RTD), number of blade passes experienced by the powder, and mean centered variance of the particle residence time. The mean centered variance and the number of blade passes exhibit a maximum with increasing impeller speed, indicating optimal mixing behavior at an intermediate speed range. The second DEM approach utilizes a periodic slice of the full blender in order to explore in detail the effect of speed, fill level, and cohesion on mixing performance. The results show that the transverse mixing rates were generally higher than the corresponding axial mixing rates. Transverse diffusion was highest for large impeller speeds at larger fills, and axial diffusion was highest for large impeller speeds at smaller fills. Variations in particle–particle cohesion within the investigated range do not affect diffusion values significantly. The axial diffusion coefficient can be reasonably predicted from the residence time distribution using the 1D advection‐diffusion model. magnified image
Logical Analysis of Data in Structure‐Activity Investigation of Polymeric Gene Delivery
Authors: Gubskaya Anna V. , Bonates Tiberius O. , Kholodovych Vladyslav , Hammer Peter , Welsh William J. , Langer Robert , Kohn Joachim 
Published: March 2011

AbstractTo date semi‐empirical or surrogate modeling has demonstrated great success in the prediction of the biologically relevant properties of polymeric materials. For the first time, a correlation between the chemical structures of poly(β‐amino esters) and their efficiency in transfecting DNA was established using the novel technique of logical analysis of data (LAD). Linear combination and explicit representation models were introduced and compared in the framework of the present study. The most successful regression model yielded satisfactory agreement between the predicted and experimentally measured values of transfection efficiency (Pearson correlation coefficient, 0.77; mean absolute error, 3.83). It was shown that detailed analysis of the rules provided by the LAD algorithm offered practical utility to a polymer chemist in the design of new biomaterials. magnified image
Macropinocytosis inhibitors and Arf6 regulate ErbB3 nuclear localization in prostate cancer cells
Authors: Koumakpayi Ismaël Hervé , Le Page Cécile , Delvoye Nathalie , Saad Fred , Mes‐Masson Anne‐Marie 
Published: March 2011

AbstractErbB3 is a transmembrane tyrosine kinase receptor among the epidermal growth factor receptor (EGFR) family that plays an important role in prostate cancer (PCa) progression. We previously demonstrated that ErbB3 is located in the nucleus of PCa cell lines and PCa tissues. It also was observed that ErbB3 nuclear localization could discriminate between benign and malignant prostate tissues as well as between hormone sensitive and hormone‐refractory PCa. Several studies have suggested a role for clathrin‐mediated endosomal sorting in the nuclear localization of EGFR and ErbB2 but the mechanisms by which ErbB receptors escape recycling or degradation are not well known. Consequently to determine the role of endocytosis in the nuclear localization of ErbB3, different endocytotic inhibitors and specific si‐RNAs were used to discriminate between clathrin‐dependent and clathrin‐independent pathways. We found that clathrin, caveolin, and membrane domains are not required for endocytosis‐mediated nuclear localization of ErbB3 in PCa cells and we provide evidence that amiloride, a macropinocytosis inhibitor, and the ADP‐ribosylation factor 6 (Arf6) are implicated in the compartimentalization of ErbB3. In conclusion, evidence for an endocytosis‐based mechanism in the nuclear localization of ErbB3 in PCa cells is proposed. These results may help elucidate new therapeutic avenues in PCa that target nuclear ErbB3, which may participate in the progression and aggressivity of the disease. © 2011 Wiley Periodicals, Inc.
Interaction of mutant hepatitis B X protein with p53 tumor suppressor protein affects both transcription and cell survival
Authors: Iyer Shoba , Groopman John D. 
Published: March 2011

AbstractThis study examines the differential activities between wild‐type Hepatitis B virus X protein (WtHBx) and a mutant HBx (MutHBx), which bears a hotspot mutation at nucleotides 1,762 and 1,764, resulting in a lysine to methionine change at codon 130 and a valine to isoleucine change at codon 131. This mutation leads to hepatocellular carcinoma, and we evaluated how WtHBx and MutHBx proteins differ in their interactions with the p53 tumor suppressor protein. This was experimentally addressed through co‐immunoprecipitation assays examining the interaction between WtHBx and MutHBx proteins with p53, reporter assays determining the impact of the HBx proteins on p53‐mediated gene transcription, and clonogenic survival assays evaluating the effect of HBx on cell growth in lines of varying p53‐expression status. Both WtHBx and MutHBx proteins physically interact with p53 protein, but have different impacts on p53‐mediated gene transcription. WtHBx did not effect p53‐mediated gene transcription, whereas MutHBx inhibited it (P < 0.01). MutHBx inhibited colony formation in p53‐proficient cells (P < 0.01), but not p53‐deficient lines. Although both HBx proteins interact with p53, they affect p53‐mediated gene transcription differently. WtHBx has no effect, whereas MutHBx inhibits it. In clonogenic survival assays, MutHBx inhibited cell growth in p53‐proficient cells rather than enhanced it. This suggests that for MutHBx to behave oncogenically, the p53 pathway must be crippled or absent. This study has identified some important novel ways in which WtHBx and MutHBx differentially interact with p53 and this could begin to form the cellular explanation for the association between this particular mutant and liver cancer. © 2011 Wiley Periodicals, Inc.
A novel role for the T‐box transcription factor Tbx1 as a negative regulator of tumor cell growth in mice
Authors: Trempus Carol S. , Wei Sung‐Jen , Humble Margaret M. , Dang Hong , Bortner Carl D. , Sifre Maria I. , Kissling Grace E. , Sunman Jeffrey A. , Akiyama Steven K. , Roberts John D. , Tucker Charles J. , Chun Kyung‐Soo , Tennant Raymond W. , Langenbach Robert 
Published: March 2011

AbstractThe T‐box transcription factor, Tbx1, an important regulatory gene in development, is highly expressed in hair follicle (HF) stem cells in adult mice. Because mouse models of skin carcinogenesis have demonstrated that HF stem cells are a carcinogen target population and contribute significantly to tumor development, we investigated whether Tbx1 plays a role in skin carcinogenesis. We first assessed Tbx1 expression levels in mouse skin tumors, and found down‐regulation in all tumors examined. To study the effect of Tbx1 expression on growth and tumorigenic potential of carcinoma cells, we transfected mouse Tbx1 cDNA into a mouse spindle cell carcinoma cell line that did not express endogenous Tbx1. Following transfection, two cell lines expressing different levels of the Tbx1/V5 fusion protein were selected for further study. Intradermal injection of the cell lines into mice revealed that Tbx1 expression significantly suppressed tumor growth, albeit with no change in tumor morphology. In culture, ectopic Tbx1 expression resulted in decreased cell growth and reduced development into multilayered colonies, compared to control cells. Tbx1‐transfectants exhibited a reduced proliferative rate compared to control cells, with fewer cells in S and G2/M phases. The Tbx1 transfectants developed significantly fewer colonies in soft agar, demonstrating loss of anchorage‐independent growth. Taken together, our data show that ectopic expression of Tbx1 restored contact inhibition to the skin tumor cells, suggesting that this developmentally important transcription factor may have a novel dual role as a negative regulator of tumor growth. © 2011 Wiley Periodicals, Inc.
Arachidonoyl ethanolamide (AEA)‐induced apoptosis is mediated by J‐series prostaglandins and is enhanced by fatty acid amide hydrolase (FAAH) blockade
Authors: Kuc Christian , Jenkins Audrey , Van Dross Rukiyah T. 
Published: March 2011

AbstractThe endocannabinoid arachidonoyl ethanolamide (AEA) is a potent inducer of tumor cell apoptosis however its mechanism of cytotoxicity is unclear. A previous report from our laboratory showed that AEA induced cell death in a cyclooxygenase‐2 (COX‐2)‐dependent manner and in this report our data indicate that AEA‐induced apoptosis is mediated by COX‐2 metabolic products of the J‐series. In experiments conducted with JWF2 keratinocytes which over‐express COX‐2, AEA caused a concentration‐regulated increase in J‐series prostaglandin production and apoptosis. Similarly, cell treatment with exogenously added J‐series prostaglandins (15‐deoxy, Δ12,14 PGJ2 and PGJ2) induced apoptosis. AEA‐induced apoptosis was inhibited by the antioxidant, N‐acetyl cysteine, indicating that reactive oxygen species generation was required for apoptosis. Using antagonists of cannabinoid receptor 1, cannabinoid receptor 2, or transient receptor potential cation channel, subfamily V, member 1, it was observed that cannabinoid receptor inhibition did not block AEA‐mediated cell death. In contrast, an inhibitor of fatty acid amide hydrolase (FAAH) potentiated AEA‐induced J‐series PG synthesis and apoptosis. These results suggest that the metabolism of AEA to J‐series PGs regulates the induction of apoptosis in cells with elevated COX‐2 levels. Our data further indicate that the proapoptotic activity of AEA can be enhanced by combining it with an inhibitor of FAAH. As such, AEA may be an effective agent to eliminate tumor cells that over‐express COX‐2. Mol. Carcinog. © 2011 Wiley Periodicals, Inc.
Whole‐body diffusion‐weighted imaging with a continuously moving table acquisition method: Preliminary results
Authors: Han Yeji , Weigel Matthias , Huff Sandra , Ludwig Ute 
Published: March 2011

AbstractIn this study, a method for whole‐body diffusion‐weighted imaging (wbDWI) during continuous table motion has been developed and implemented on a clinical scanner based on a short‐Tau inversion recovery echo‐planar DWI sequence. Unlike currently available multistation wbDWI, which has disadvantages such as long scanning times, poor image quality, and troublesome data realignment, continuously moving table wbDWI can overcome these technical problems while extending the longitudinal field of view in MRI systems. In continuously moving table wbDWI, images are acquired consecutively at the isocenter of the magnet, having less geometric distortions and various possibilities of spatial and temporal coverage of an extended field of view. The acquired images, together with an apparent diffusion coefficient analysis, show that continuously moving table wbDWI can be used by appropriately adapting the table velocity, scan range, radiofrequency coils, slice resolutions, and spatio‐temporal acquisition schemes according to various clinical demands. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Identification of signal bias in the variable flip angle method by linear display of the algebraic ernst equation
Authors: Helms Gunther , Dathe Henning , Weiskopf Nikolaus , Dechent Peter 
Published: March 2011

AbstractA novel linear parameterization for the variable flip angle method for longitudinal relaxation time T1 quantification from spoiled steady state MRI is derived from the half angle tangent transform, τ, of the flip angle. Plotting the signal S at coordinates x = Sτ and y = S/τ, respectively, establishes a line that renders signal amplitude and relaxation term separately as y‐intercept and slope. This representation allows for estimation of the respective parameter from the experimental data. A comprehensive analysis of noise propagation is performed. Numerical results for efficient optimization of longitudinal relaxation time and proton density mapping experiments are derived. Appropriate scaling allows for a linear presentation of data that are acquired at different short pulse repetition times, TR << T1 thus increasing flexibility in the data acquisition by removing the limitation of a single pulse repetition time. Signal bias, like due to slice‐selective excitation or imperfect spoiling, can be readily identified by systematic deviations from the linear plot. The method is illustrated and validated by 3T experiments on phantoms and human brain. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Optimizing pulsed‐chemical exchange saturation transfer imaging sequences
Authors: Zu Zhongliang , Li Ke , Janve Vaibhav A. , Does Mark D. , Gochberg Daniel F. 
Published: March 2011

AbstractChemical exchange saturation transfer (CEST) provides a new imaging contrast mechanism sensitive to labile proton exchange. Pulsed‐CEST imaging is better suited to the hardware constraints on clinical imaging systems when compared with traditional continuous wave‐CEST imaging methods. However, designing optimum pulsed‐CEST imaging sequences entails complicated and time‐consuming numerical integrations. In this work, a simplified and computationally efficient technique is provided to optimize the pulsed‐CEST imaging sequence. An analysis was performed of the optimal average irradiation power and the optimal irradiation flip angle as a function of the acquisition parameters and sample properties in both a two‐pool model and a three‐pool model of endogenous amine exchange. Key simulated and experimental results based on a creatine/agar tissue phantom show that (1) the average irradiation power is a more meaningful sequence metric than is the average irradiation field amplitude, (2) the optimal average powers for continuous wave and pulsed‐CEST imaging are approximately equal to each other for a relevant range of solute frequency offsets, exchange rates, and concentrations, (3) an irradiation flip angle of 180° is optimal or near optimal, independent of the other acquisition parameters and the sample properties, and (4) higher duty cycles yield higher CEST contrast. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Generation of an atlas of the proximal femur and its application to trabecular bone analysis
Authors: Carballido‐Gamio Julio , Folkesson Jenny , Karampinos Dimitrios C. , Baum Thomas , Link Thomas M. , Majumdar Sharmila , Krug Roland 
Published: March 2011

AbstractAutomatic placement of anatomically corresponding volumes of interest and comparison of parameters against a standard of reference are essential components in studies of trabecular bone. Only recently, in vivo MR images of the proximal femur, an important fracture site, could be acquired with high‐spatial resolution. The purpose of this MRI trabecular bone study was two‐fold: (1) to generate an atlas of the proximal femur to automatically place anatomically corresponding volumes of interest in a population study and (2) to demonstrate how mean models of geodesic topological analysis parameters can be generated to be used as potential standard of reference. Ten females were used to generate the atlas and geodesic topological analysis models, and 10 females were used to demonstrate the atlas‐based trabecular bone analysis. All alignments were based on three‐dimensional (3D) multiresolution affine transformations followed by 3D multiresolution free‐form deformations. Mean distances less than 1 mm between aligned femora, and sharp edges in the atlas and in fused gray‐level images of registered femora indicated that the anatomical variability was well accommodated and explained by the free‐form deformations. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Humerus Varus in a Subadult Skeleton from the Medieval Graveyard of La Madeleine (Orléans, France)
Authors: Kacki S. , Duneufjardin P. , Blanchard P. , Castex D. 
Published: March 2011

ABSTRACTThe skeleton of a subadult individual from the medieval graveyard of La Madeleine (Orléans, France) exhibits varus deformity of its right humerus. The affected bone is shortened, the diaphysis is angulated and the head is grossly deformed. The skeleton is otherwise normal. Several diagnoses are debated, including mucopolysaccharidoses, thalassemia, infection and trauma, the latter being preferred. The severity of the bone changes suggests that the growth disturbance occurred early in the life of the individual. We therefore suppose that the causative trauma occurred at the time of birth or during the early postnatal period. Copyright © 2011 John Wiley & Sons, Ltd.
A Viscoplastic‐Damage Model for the Lifetime Prediction of Regeneratively Cooled Noozle Structures
Authors: Tini Vivian , Reese Stefanie 
Published: March 2011

AbstractThe cooling channel wall within the combustion chamber of a Reusable Launch Vehicle (RLV) is subjected to severe operating conditions which eventually lead to the damage of the wall. The failure mode is well known as the “dog‐house” effect where the wall becomes thinner and bulges toward the interior of the chamber. Supported by the German Research Foundation, a viscoplastic‐damage model is being developed to enable a realistic description of the material behaviour under extreme cyclic thermomechanical loadings where creep and hardening phenomena might take place. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling of growth inhomogeneities in timber structures for realistic computations
Authors: Jenkel Christian , Lang Ronny , Kaliske Michael 
Published: March 2011

AbstractThis contribution discusses the numerical analysis of timber structures by means of the Finite Elements Method. As a naturally grown and fibrous material, wood shows distinctive material directions, which are captured by a cylindrically anisotropic model. Due to the growth conditions of a tree, the fiber course in wooden structural parts can differ. Especially branches, leading to knots, affect the mechanical properties. Therefore, an approach for the modelling of these growth inhomogeneities is presented. For the three‐dimensional determination of the fiber course in the area of the inhomogeneities, an optimization procedure, using the idea of minimization of shear stresses in tree growth, has been developed. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bifurcation of slow motions in a stiff spring pendulum
Authors: Steindl Alois 
Published: March 2011

AbstractWe consider free oscillations of a double pendulum, where one of the pendula is modelled as a very stiff spring. Contrary to a single spring pendulum numerical simulations show an unexpected large influence of the fast longitudinal oscillations on the slow pendulum oscillations even for extremely large values of the stiffness. The transition from the regular motion, which is governed by the dynamics of a rigid double pendulum close to a periodic orbit, to the irregular motion with large contributions from the longitudinal oscillations occurs due to a subcritical symmetry breaking bifurcation of the periodic solution. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phase‐field modeling of the effect of interfacial energy on pyrolytic carbon morphology in chemical vapor deposition
Authors: Li Aijun , Deutschmann Olaf , Piat Romana , Böhlke Thomas , Tsukrov Igor , Gross Todd 
Published: March 2011

AbstractA conserved phase‐field model is proposed to investigate the effect of interfacial energy on the morphological evolution of the pyrolytic carbon deposit in chemical vapor deposition. The equilibrium geometry of carbon deposit islands is analytically predicted, of which the contact angle was controlled through the boundary conditions of the phase‐field parameter at the substrate surface according to the Young‐Laplace equation. Simulations of deposit growth are carried out for single and multi island nucleation. It is clarified that the island morphology depends on the magnitude of the interface energy. It is also observed that high interface energy results in large island size fluctuation. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Studies of the Influence of the Porosity on Macroscopic Elastic Properties of Carbon/Carbon Composites
Authors: Piat R. , Böhlke T. , Deutschmann O. , Dietrich S. , Drach B. , Gebert J.‐M. , Gross T. , Li A. , Reznik B. , Stasiuk G. , Tsukrov I. , Wanner A. 
Published: March 2011

AbstractMaterial parameter identification of the carbon/carbon composites was provided using numerical implementation of semi‐analytical methods and FE‐calculations. The distribution of the fibers and pores obtained from microstructural studies is used as input for homogenization schemes for the determination of the effective elastic constants. The predictions are compared to experimental results. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of the semy‐analytical micromechanical methods for optimization of the elastic response of metal‐ceramic composites
Authors: Piat Romana , Sinchuk Yuriy , Vasoya Manishkumar 
Published: March 2011

AbstractMetal‐ceramic composites produced by melt infiltration of the ceramic preform were studied. The ceramic preform of these materials is manufactured through freeze‐casting process and the microstructure can be presented as distribution of the lamellar domains. Micromechanical models were used for the calculation of the effective elastic properties of the domains. The minimum compliance problem was solved for sample subjected to the four‐point bending test. The optimal orientation and volume fracture of the micro constituents were identified using different models. The difference between the initial and optimized design was analyzed. The convergence of the provided optimization procedure was very rapid. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical estimation of the thermal expansion of lamellar single domains in metal/ceramic composites
Authors: Stasiuk Galyna , Ziegler Tobias , Piat Romana , Neubrand Achim 
Published: March 2011

AbstractA porous ceramic preform, the pore structure of which is created via a freeze‐casting technique, is infiltrated with a metal melt via sqeeze‐casting. The microstructure of the obtained metal/ceramic composites has lamellar domains with geometrical characteristics which are dependent on the manufacturing parameters. The aim of our study is to predict the coefficients of thermal expansion of single domains of parallel Al2O3 platelets embedded in Al. For this purpose, a homogenization procedure was employed for microstructure based finite element and micromechanical modeling. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)