bluuebunny/crossref_metadata_2025_split huggingface dataset:
On perfect Γ‐decompositions of the complete graph
Authors: Buratti Marco , Pasotti Anita 
Published: July 2008

AbstractGeneralizing the well‐known concept of an i‐perfect cycle system, Pasotti [Pasotti, in press, Australas J Combin] defined a Γ‐decomposition (Γ‐factorization) of a complete graph Kv to be i‐perfect if for every edge [x, y] of Kv there is exactly one block of the decomposition (factor of the factorization) in which x and y have distance i. In particular, a Γ‐decomposition (Γ‐factorization) of Kv that is i‐perfect for any i not exceeding the diameter of a connected graph Γ will be said a Steiner (Kirkman) Γ‐system of order v. In this article we first observe that as a consequence of the deep theory on decompositions of edge‐colored graphs developed by Lamken and Wilson [Lamken and Wilson, 2000, J Combin Theory Ser A 89, 149–200], there are infinitely many values of v for which there exists an i‐perfect Γ‐decomposition of Kv provided that Γ is an i‐equidistance graph, namely a graph such that the number of pairs of vertices at distance i is equal to the number of its edges. Then we give some concrete direct constructions for elementary abelian Steiner Γ‐systems with Γ the wheel on 8 vertices or a circulant graph, and for elementary abelian 2‐perfect cube‐factorizations. We also present some recursive constructions and some results on 2‐transitive Kirkman Γ‐systems. © 2008 Wiley Periodicals, Inc. J Combin Designs 17: 197–209, 2009
PML/RARα fusion protein mediates the unique sensitivity to arsenic cytotoxicity in acute promyelocytic leukemia cells: Mechanisms involve the impairment of cAMP signaling and the aberrant regulation of NADPH oxidase
Authors: Li Lingna , Wang Jie , Ye Richard D. , Shi Guiying , Jin Huifang , Tang Xueming , Yi Jing 
Published: July 2008

AbstractAcute promyelocytic leukemia (APL) cells are characterized by PML/RARα fusion protein, high responsiveness to arsenic trioxide (ATO)‐induced cytotoxicity and an abundant generation of reactive oxygen species (ROS). In this study we investigated the association among these three features in APL‐derived NB4 cells. We found that NADPH oxidase‐derived ROS generation was more abundant in NB4 cells compared with monocytic leukemia U937 cells. By using PR9, a sub‐line of U937 stably transduced with the inducible PML/RARα expression vectors, we attributed disparities on ROS generation and ATO sensitivity to the occurrence of PML/RARα fusion protein, since PML/RARα‐expressing cells appeared higher NADPH oxidase activity, higher ROS level and higher sensitivity to ATO. On the other hand, the basal intensity of cAMP signaling pathway was compared between NB4 and U937 as well as between PR9 cells with or without PML/RARα, demonstrating that PML/RARα‐expressing cells had an impaired cAMP signaling pathway which relieved its inhibitory effect on NADPH oxidase derived ROS generation. In summary, the present study demonstrated the correlation of PML/RARα with cAMP signaling pathway, NADPH oxidase and ROS generation in APL cells. PML/RARα that bestows NB4 cells various pathological features, paradoxically also endows these cells with the basis for susceptibility to ATO‐induced cytotoxcity. J. Cell. Physiol. 217: 486–493, 2008. © 2008 Wiley‐Liss, Inc.
Shear stress‐induced Ets‐1 modulates protease inhibitor expression in microvascular endothelial cells
Authors: Milkiewicz Malgorzata , Uchida Cassandra , Gee Eric , Fudalewski Tomasz , Haas Tara L. 
Published: July 2008

AbstractElevated shear stress within the skeletal muscle microvasculature is implicated in the induction of a longitudinal splitting form of angiogenesis, which is characterized by the lack of basement membrane breakage. We investigated whether the transcriptional regulator, Ets‐1, is responsive to changes in hemodynamic forces and if so, whether Ets‐1 controls microvascular endothelial cell integrity by inducing the expression of inhibitors of matrix degrading proteases. Rats were treated with prazosin for 2, 4, and 7 days to increase in microvascular shear stress in hindlimb skeletal muscles. In complimentary in vitro experiments, rat microvascular skeletal muscle endothelial cells were exposed to laminar shear stress (15 dyne/cm2) for 0.5, 2, and 24 h. TaqMan PCR analysis of laser microdissected capillaries isolated from EDL muscles demonstrated transient (after 2 days) induction of Ets‐1 gene expression. In cultured cells, a transient up‐regulation of Ets‐1 mRNA was observed after 2 h shear stimulation, accompanied by increased phosphorylation of Ets‐1 and enhanced Ets‐1 DNA binding activity. This response was modulated by ERK1/2 and p38 MAP kinases, but was not dependent on NOS or COX‐2 activity. PAI‐1, TIMP‐1 and TIMP‐3 mRNA were elevated significantly in prazosin treated EDL, and in response to shear stimulation in vitro. In cultured endothelial cells, Ets‐1 RNA interference abolished the shear‐induced increases in Ets‐1, PAI‐1, TIMP‐1, and TIMP‐3 mRNA expression. These results suggest that enhanced laminar shear stress may act to preserve the integrity of microvascular walls in part through Ets‐1‐dependent induction of protease inhibitors. J. Cell. Physiol. 217: 502–510, 2008. © 2008 Wiley‐Liss, Inc.
Role of the hemopexin domain of matrix metalloproteinases in cell migration
Authors: Dufour Antoine , Sampson Nicole S. , Zucker Stanley , Cao Jian 
Published: July 2008

AbstractThe biological functions of matrix metalloproteinases (MMPs) extend beyond extracellular matrix degradation. Non‐proteolytic activities of MMPs are just beginning to be understood. Herein, we evaluated the role of proMMPs in cell migration. Employing a Transwell chamber migration assay, we demonstrated that transfection of COS‐1 cells with various proMMP cDNAs resulted in enhancement of cell migration. Latent MMP‐2 and MMP‐9 enhanced cell migration to a greater extent than latent MMP‐1, ‐3, ‐11 and ‐28. To examine if proteolytic activity is required for MMP‐enhanced cell migration, three experimental approaches, including fluorogenic substrate degradation assay, transfection of cells with catalytically inactive mutant MMP cDNAs, and addition of hydroxamic acid‐derived MMP inhibitors, were employed. We demonstrated that the proteolytic activities of MMPs are not required for MMP‐induced cell migration. To explore the mechanism underlying MMP‐enhanced cell migration, structure‐function relationship of MMP‐9 on cell migration was evaluated. By using a domain swapping approach, we demonstrated that the hemopexin domain of proMMP‐9 plays an important role in cell migration when examined by a transwell chamber assay and by a phagokinetic migration assay. TIMP‐1, which interacts with the hemopexin domain of proMMP‐9, inhibited cell migration, whereas TIMP‐2 had no effect. Employing small molecular inhibitors, MAPK and PI3K pathways were found to be involved in MMP‐9‐mediated cell migration. In conclusion, we demonstrated that MMPs utilize a non‐proteolytic mechanism to enhance epithelial cell migration. We propose that hemopexin homodimer formation is required for the full cell migratory function of proMMP‐9. J. Cell. Physiol. 217: 643–651, 2008. © 2008 Wiley‐Liss, Inc.
Time‐domain simulation of electromagnetic wave propagation in two‐level dielectrics
Authors: Paul J. , Christopoulos C. , Thomas D. W. P. 
Published: July 2008

AbstractA method for the time‐domain simulation of electromagnetic wave propagation in two‐level dielectric media is developed. The technique involves using transmission‐line modelling (TLM) and 𝒵‐transform methods to develop an algorithm to simulate the Maxwell–Bloch equations. The approach is accurate and free from numerical instabilities. The scheme was validated for the small‐signal case by demonstration of the correspondence principle with the classical Lorentz oscillator. Results obtained for propagation in the two‐level medium are in agreement with previous studies in the literature. In addition, results are shown demonstrating gain, self‐induced transparency (SIT), Rabi flopping and laser oscillations. Copyright © 2008 John Wiley & Sons, Ltd.
Microstrip antenna analysis using the method of fundamental solutions
Authors: Sensale‐Rodriguez Berardi , Sensale Berardi , Leitão Vitor M. A. , Peixeiro Custódio 
Published: July 2008

AbstractThe method of fundamental solutions (MFS) is proposed for the analysis of microstrip patch antennas of arbitrary shape. The MFS consists mainly in approximating the solution of a problem by a linear combination of known fundamental solutions associated with source points located outside the domain. The implementation of the MFS is simple and computationally efficient. Simulation results are obtained for rectangular, circular and triangular microstrip patch antennas. The resonance frequency and input impedance results are in good agreement with those published in the literature. Two prototypes have been fabricated and tested. Good agreement has been obtained between the MFS simulations and the experimental results. Copyright © 2008 John Wiley & Sons, Ltd.
Food and feed components for gut health‐promoting adhesion of E. coli and Salmonella enterica
Authors: Becker Petra M , Galletti Sara 
Published: July 2008

AbstractBACKGROUND: A host runs less risk of contracting a gastrointestinal infection when enteropathogenic bacteria adhere to dietary fibers instead of to epithelial cell receptors. The aim of this study was to test the binding capacity of food and feed components for intestinal bacteria from various hosts using a miniaturized in vitro assay. In total, 18 dietary components were tested with four strains of E. coli, seven strains of Salmonella enterica and two strains of Lactobacillus.RESULTS: A comparison of the results obtained for all Salmonella strains tested revealed that konjac gum and sesame seed extract represented the most efficient binding matrices. Similarly, for all E. coli strains tested, sesame seed extract and artichoke performed well as binding matrices. Salmonella isolates from chickens adhered best to sesame seed extract. E. coli K88 and S. enterica sv. Typhimurium isolated from pigs effectively bound to BioMos®, pumpkin, sesame seed extract, and tomato. Sesame seed extract and tomato also had adhesive capacities for E. coli K 99, S. enterica sv. Dublin, and S. enterica sv. Typhimurium from calves. With human isolates, konjac gum showed a high binding potential for S. enterica and E. coli.CONCLUSION: The adhesion screening of different food and feed components resulted in highly discriminating product rankings. Copyright © 2008 Society of Chemical Industry
Experimental measurements and theoretical calculations of the chemical shifts and coupling constants of three azines (benzalazine, acetophenoneazine and cinnamaldazine)
Authors: Silva Artur M. S. , Sousa Regina M. S. , Jimeno María Luisa , Blanco Fernando , Alkorta Ibon , Elguero José 
Published: July 2008

AbstractThree azines, two of them doubly labeled with 15N, have been studied by multinuclear magnetic resonance in solution and in the solid state. The spectral parameters obtained by iterative analyses have been compared with DFT/B3LYP calculated values (absolute shieldings and coupling constants). The agreement is generally good. Some anomalies have been discussed in relation to the structure of these compounds. Copyright © 2008 John Wiley & Sons, Ltd.
Improving accuracy and efficiency of blind protein‐ligand docking by focusing on predicted binding sites
Authors: Ghersi Dario , Sanchez Roberto 
Published: July 2008

AbstractThe use of predicted binding sites (binding sites calculated from the protein structure alone) is evaluated here as a tool to focus the docking of small molecule ligands into protein structures, simulating cases where the real binding sites are unknown. The resulting approach consists of a few independent docking runs carried out on small boxes, centered on the predicted binding sites, as opposed to one larger blind docking run that covers the complete protein structure. The focused and blind approaches were compared using a set of 77 known protein‐ligand complexes and 19 ligand‐free structures. The focused approach is shown to: (1) identify the correct binding site more frequently than blind docking; (2) produce more accurate docking poses for the ligand; (3) require less computational time. Additionally, the results show that very few real binding sites are missed in spite of focusing on only three predicted binding sites per target protein. Overall the results indicate that, by improving the sampling in regions that are likely to correspond to binding sites, the focused docking approach increases accuracy and efficiency of protein ligand docking for those cases where the ligand‐binding site is unknown. This is especially relevant in applications such as reverse virtual screening and structure‐based functional annotation of proteins. Proteins 2009. © 2008 Wiley‐Liss, Inc.
The mechanism of amyloid‐fibril formation by stefin B: Temperature and protein concentration dependence of the rates
Authors: Škerget Katja , Vilfan Andrej , Pompe‐Novak Maruša , Turk Vito , Waltho Jonathan P. , Turk Dušan , Žerovnik Eva 
Published: July 2008

AbstractCystatins, a family of structurally related cysteine proteinase inhibitors, have proved to be useful model system to study amyloidogenesis. We have extended previous studies of the kinetics of amyloid‐fibril formation by human stefin B (cystatin B) and some of its mutants, and proposed an improved model for the reaction. Overall, the observed kinetics follow the nucleation and growth behavior observed for many other amyloidogenic proteins. The minimal kinetic scheme that best fits measurements of changes in CD and thioflavin T fluorescence as a function of protein concentration and temperature includes nucleation (modeled as NI irreversible transitions with equivalent rates (kI), which fitted with NI = 64), fibril growth and nonproductive oligomerization, best explained by an off‐pathway state with a rate‐limiting escape rate. Three energies of activation were derived from global fitting to the minimal kinetic scheme, and independently through the fitting of the individual component rates. Nucleation was found to be a first‐order process within an oligomeric species with an enthalpy of activation of 55 ± 4 kcal mol−1. Fibril growth was a second‐order process with an enthalpy of activation (27 ± 5 kcal mol−1), which is indistinguishable from that of tetramer formation by cystatins, which involves limited conformational changes including proline trans to cis isomerization. The highest enthalpy of activation (95 ± 5 kcal mol−1 at 35°C), characteristic of a substantial degree of unfolding as observed prior to domain‐swapping reactions, equated with the escape rate of the off‐pathway oligomeric state. Proteins 2009. © 2008 Wiley‐Liss, Inc.
Evaluation of implanted InSb p+n diodes passivated with composite anodic oxide/SiOxstack
Authors: Liu K. C. , Luo J. J. , Dai L. K. 
Published: July 2008

AbstractThis investigation presents detailed characteristics of an implanted planar InSb p+n diode with a junction area scaled down to 20 × 20 μm2. Low‐temperature photo‐chemical vapor deposition oxide stacked with an optimized thin anodic film, instead of a gate control structure, is used to control the planar surface potential of the implanted p+n diode under the weak inversion condition on the n‐type surface and under weak accumulation on the p‐type surface. The zero‐bias resistance–area product is 7.6 × 104Ω cm2at 77 K. To the best of the authors' knowledge, this result represents the best performance of a small‐area and implanted planar diode to date. The dark current is controlled by an internal shunt conduction mechanism, which seems to be related to the defects that are produced by the implantation. Low leakage current and high breakdown voltage have proven the feasibility of the composite anodic oxide/SiOxthat is stacked as the passivation structure in small‐pixel InSb p+n photodiodes for focal plane array applications. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Switching thresholds in MTJ using SPICE model – Effects of spin and Ampere torques
Authors: Malathi M. , Prabhakar A. 
Published: July 2008

AbstractSpin torque due to spin polarized tunneling current can be used to switch the free layer in a magnetic tunnel junction (MTJ). This current also gives rise to an Ampere torque, which influences the switching threshold of the MTJ. We modified the Landau–Lifschitz–Gilbert equation (LLGE) to include an Ampere torque term and solved for the magnetization dynamics under the single domain approximation using a linear solver in SPICE. We also extend the model to a square array of MTJs to study the effect of nearest neighbour interactions in addition to effects like demagnetization and magnetostatic interactions with the pinned layer. The interlayer exchange field between the free and pinned layers of a MTJ and the spin torque are competing factors that decide the threshold current density for switching the MTJ. We used a two current model to study the effects of barrier height and barrier thickness on spin torque and exchange energy. We observe that both the spin torque and exchange energy decrease with an increase in barrier height (for ferromagnetic coupling) and barrier thickness. We find that the inclusion of Ampere torque causes a reduction in the switching current. Varying the thickness of MgO and Al2O3 barriers allows us to minimize the switching threshold voltage. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preparation, structure and gas‐sensing properties of γ‐Fe2O3 and γ‐Fe2O3–TiO2 thick films
Authors: Rezlescu E. , Doroftei C. , Rezlescu N. , Popa P. D. 
Published: July 2008

AbstractIn this paper, the preparation of γ‐Fe2O3 and γ‐Fe2O3–TiO2 thick films by a screen printing method is presented and their sensitivities and responses to acetone, ethyl alcohol, ammonia and liquefied petroleum gas are studied. The experimental results revealed that the gas sensitivity is strongly related to operating temperature, film composition and gas type. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical transport in boron‐doped polycrystalline zinc oxide thin films
Authors: Steinhauser J. , Faÿ S. , Oliveira N. , Vallat‐Sauvain E. , Zimin D. , Kroll U. , Ballif C. 
Published: July 2008

AbstractBoron doped Zinc oxide (ZnO:B) thin films are commonly used as transparent conductive oxide (TCO) in thin film silicon solar cells. TCO films with a high electrical conductivity combined with a high transparency are required for this application. In this paper, the electronic transport properties in polycrystalline ZnO:B grown by low pressure chemical vapor deposition (LPCVD) were investigated using Hall effect measurements and optical spectroscopy techniques. The systematic comparison between the optical mobility values deduced from the reflectance spectra using the Drude model, and the Hall mobility values, allowed us to clearly separate the respective influences on the electrical transport of potential barrier at grain boundaries and intragrain scattering. By analyzing the results for samples with large variation of grain size and doping level, we observed a continuous transition from grain boundary scattering to intragrain scattering. Finally, the stability of LPCVD ZnO:B in a humid environment was also investigated. The degradation of the electrical film properties due to damp heat treatment is analyzed and discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Indium oxide thin‐film transistor by reactive ion beam assisted deposition
Authors: Vygranenko Y. , Wang K. , Vieira M. , Nathan A. 
Published: July 2008

AbstractThis work reports on the fabrication and characterization of indium oxide semiconducting films and their application in thin‐film transistors (TFTs). The films have been deposited at room temperature by oxygen ion beam assisted e‐beam evaporation. The influence of deposition conditions on film properties including the crystal structure, conductivity, and intrinsic stress is analyzed. It is found that the electrical properties of indium oxide films can be engineered from metallic to insulating and the film structure can be varied from amorphous to microcrystalline by adjusting deposition rate, oxygen ion energy, and ion beam flux. Furthermore, the highly‐resistive films with considerable microstructural crystallinity exhibit n‐type field‐effect behaviour. A field‐effect mobility of 1.4 cm2/V s, and ON/OFF current ratio of ∼106 are observed for transistors with a silicon dioxide gate dielectric. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Novel III‐nitride based transparent photodetectors for standing wave interferometry
Authors: Hauguth S. , Lebedev V. , Mauder Ch. , Niebelschütz F. , Büchner H.‐J. , Jäger G. , Ambacher O. 
Published: July 2008

AbstractThe concept of a standing wave (SW) interferometer has been extensively investigated for the last decade. A key problem within these efforts is the development of a transparent ultra‐thin photodetector for sampling the intensity profile of the generated SW. We report on the simulation and fabrication as well as on the structural and optoelectronical characterization of highly transparent AlGaN/GaN double‐heterostructure and InGaN metal–semiconductor–metal photodetectors based on intraband and band‐to‐band transitions, respectively. Both detectors have a 20 nm thick optically active layer designed for the light absorption at the wavelength of ∼633 nm. Besides good structural properties of both Al0.35Ga0.65N/GaN and In0.56Ga0.44N structures, the absorbance of the InGaN‐based detector was found ∼20 times higher compared to the AlGaN/GaN photodetectors. The temporal characteristics of the detectors are limited by both the RC‐constant and by the persistent photocurrent effect. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nanostructuring of an AlGaInP light emitting diode for surface plasmon enhanced emission of light output
Authors: Perks R. M. , Kettle J. , Lalev G. M. , Dimov S. 
Published: July 2008

AbstractThis work describes a successful post fabrication method of applying a plasmonic grating to the surface of a mounted AlGaInP LED device. A Carl Zeiss 1540 XB Focused Ion beam system was used to mill holes in a thin gold layer with a periodicity of around 540 nm. Measurements of the total light output of the device compared with a standard un‐textured device show that the plasmonic grating was found to significantly affect the light output characteristics such that the overall light output was reduced. This is attributed to the fact that only p‐polarised light can interact with the hole array. Furthermore, the onset of saturation in the textured device was not evident as compared with the un‐textured device. This is attributed to improved current spreading in the device due to the top gold layer. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Development and characterization of light‐emitting diodes (LEDs) based on ruthenium complex single layer for transparent displays
Authors: Santos G. , Fonseca F. , Andrade A. M. , Patrocínio A. O. T. , Mizoguchi S. K. , Murakami Iha N. Y. , Peres M. , Monteiro T. , Pereira L. 
Published: July 2008

AbstractIn this work, two ruthenium complexes, [Ru(bpy)3](PF6)2 and [Ru(ph2phen)3](PF6)2 in poly(methylmethacrylate) matrix were employed to build single‐layer light‐emitting electrochemical cells by spin coating on indium tin oxide substrate. In both cases the electroluminescence spectra exhibit a relatively broad band with maxima near to 625 nm and CIE (x, y) color coordinates of (0.64, 0.36), which are comparable with the photoluminescence data in the same medium. The best result was obtained with the [Ru(bpy)3](PF6)2 device where the optical output power approaches 10 µW at the band maximum with a wall‐plug efficiency higher than 0.03%. The lowest driving voltage is about 4 V for an electrical current of 20 mA. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)