bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthetic Genetic Array Analysis in Saccharomyces cerevisiae Provides Evidence for an Interaction Between RAT8/DBP5 and Genes Encoding P-Body Components
Authors: Scarcelli John J , Viggiano Susan , Hodge Christine A , Heath Catherine V , Amberg David C , Cole Charles N 
Published: August 2008

Abstract
Coordination of the multiple steps of mRNA biogenesis helps to ensure proper regulation of gene expression. The Saccharomyces cerevisiae DEAD-box protein Rat8p/Dbp5p is an essential mRNA export factor that functions at the nuclear pore complex (NPC) where it is thought to remodel mRNA/protein complexes during mRNA export. Rat8p also functions in translation termination and has been implicated in functioning during early transcription. We conducted a synthetic genetic array analysis (SGA) using a strain harboring the temperature-sensitive rat8-2 allele. Although RAT8 had been shown to interact genetically with &gt;15 other genes, we identified &gt;40 additional genes whose disruption in a rat8-2 background causes synthetic lethality or dramatically reduced growth. Included were five that encode components of P-bodies, sites of cytoplasmic mRNA turnover and storage. Wild-type Rat8p localizes to NPCs and diffusely throughout the cell but rat8-2p localized to cytoplasmic granules at nonpermissive temperature that are distinct from P-bodies. In some genetic backgrounds, these granules also contain poly(A)-binding protein, Pab1p, and additional mRNA export factors. Although these foci are distinct from P-bodies, the two merge under heat-stress conditions. We suggest that these granules reflect defective mRNP remodeling during mRNA export and during cytoplasmic mRNA metabolism.
Maternal Phosphatase Inhibitor-2 Is Required for Proper Chromosome Segregation and Mitotic Synchrony During Drosophila Embryogenesis
Authors: Wang Weiping , Cronmiller Claire , Brautigan David L 
Published: August 2008

AbstractProtein phosphatase-1 (PP1) is a major Ser/Thr phosphatase conserved among all eukaryotes, present as the essential GLC7 gene in yeast. Inhibitor-2 (I-2) is an ancient PP1 regulator, named GLC8 in yeast, but its in vivo function is unknown. Unlike mammals with multiple I-2 genes, in Drosophila there is a single I-2 gene, and here we describe its maternally derived expression and required function during embryogenesis. During oogenesis, germline expression of I-2 results in the accumulation of RNA and abundant protein in unfertilized eggs; in embryos, the endogenous I-2 protein concentrates around condensed chromosomes during mitosis and also surrounds interphase nuclei. An I-2 loss-of-function genotype is associated with a maternal-effect phenotype that results in drastically reduced progeny viability, as measured by reduced embryonic hatch rates and larval lethality. Embryos derived from I-2 mutant mothers show faulty chromosome segregation and loss of mitotic synchrony in cleavage-stage embryos, patchy loss of nuclei in syncytial blastoderms, and cuticular pattern defects in late-stage embryos. Transgenic expression of wild-type I-2 in mutant mothers gives dose-dependent rescue of the maternal effect on embryo hatch rate. We propose that I-2 is required for proper chromosome segregation during Drosophila embryogenesis through the coordinated regulation of PP1 and Aurora B.
Discrete thermodynamics of chemical equilibria and classical limit in thermodynamic simulation
Authors: Zilbergleyt Boris 
Published: August 2008

AbstractThis article sets forth comprehensive basic concepts of the discrete thermodynamics of chemical equilibrium as balance between internal and external thermodynamic forces. Conditions of chemical equilibrium in the open chemical system are obtained in the form of a logistic map, containing only one new parameter that defines the chemical system's resistance to external impact and its deviation from thermodynamic equilibrium. Solutions to the basic map are bifurcation diagrams that have quite traditional shape but the diagram areas feature specific meanings for chemical systems and constitute the system's domain of states. The article is focused on two such areas: the area of “true” thermodynamic equilibrium and the area of open chemical equilibrium. The border between them represents the classical limit, a transition point between the classical and newly formulated equilibrium conditions. This limit also separates regions of the system ideality, typical for isolated classical systems, and non‐ideality due to the limitations imposed on the open system from outside. Numerical examples illustrating the difference between results of classical and discrete thermodynamic simulation methods are presented. The article offers an analytical formula to find the classical limit, compares analytical results with these obtained by simulation, and shows the classical limit dependence upon the chemical reaction stoichiometry and robustness.
A mathematical model of powder components oxidation during thermal spray process
Authors: Kossenko Alexey , Lugovskoy Alex , Zinigrad Michael 
Published: August 2008

AbstractA model developed on the basis of kinetic principles of mass transfer allows performing computer simulation of the oxidation of powder materials during the thermal spray process. Such simulation enables one to determine the oxidation degree of the powder. The calculation is based on determining quasi‐stationary oxygen diffusion flow on a flying particle. Calculations performed for various spray powders and various flammable gases demonstrate a significant decrease of the oxidation degree with the growth of the particle diameter and density of a spray powder. The calculation results were confirmed by experiments.
Computer simulation of internal oxidation and its application to heating‐up experiments for determination of oxygen diffusivities metals—palladium as an example
Authors: Gegner Jürgen 
Published: August 2008

AbstractInternal oxidation of metal alloys is of great applicational significance as an effective dispersion‐hardening technique, e.g., for Ag, Cu, or Ni alloys, as well as having undesirable side effects to many heat treatment technologies of steels. Wagner's kinetics theory comprises three practically important restrictions: (1) homogeneous initial concentration distribution of the alloying metal M, (2) isobaric, and (3) isothermal processes. The presented new computer model, which is based on an iterative solution of Fick's 2nd law for the inward diffusion of oxygen with internal reaction, overcomes these limitations. Illustrative processes are simulated. Considering the restrictions of Wagner's theory, incomplete isothermal isobaric internal oxidation of dilute homogeneous binary alloys represents an established experimental method for determining the diffusion coefficient of oxygen in the matrix metal: the sought Arrhenius equation is derived by carrying out annealing series at several constant temperatures. The modified simulation‐aided measuring technique of incomplete nonisothermal isobaric internal oxidation, introduced in the present work, reduces the necessary experimental time considerably. Also, as a test of the new computer model, the mathematical evaluation of the data obtained by microscopic analysis of polished cross‐sections is performed by means of this tool. To demonstrate the applicability of the novel experimental technique of temperature‐programmed internal oxidation, the diffusivity of oxygen in palladium is exemplarily measured this way in a Pd‐9.19 at.% Fe alloy and, expressed in cm2/s, found to be DO = 5.32·10−1 · exp(‐18728.27/T). Here, the temperature T ranges from 1073 to 1473 K. This result is compared with literature sources and agrees well with previously published reliable data.
The features of ribbon‐like polymers in thin films
Authors: Arinstein Arkadii 
Published: August 2008

AbstractThe features of ribbon‐like polymers in thin film, which are anisotro‐pic in cross section, are considered using a lattice model of oriented self‐correlated walks (OSCW). The local properties of the ribbon‐like chain are assumed to be strongly anisotropic: bending is possible only in the plane of the ribbon (the orientation of this plane can change due to molecule twist). On the basis of this model, the phase transition of the ribbon‐like polymers possessing certain bending and twist rigidity into the rotator phase is described in the mean‐field approximation. The dimension reducing of the polymer system results in an increase of phase transition temperature. Moreover, spontaneous polarization arises in a non‐orientated system and that is the most interesting phenomenon caused by confinement of polymer macromolecules.
Thermodynamic modeling of iron oxide reduction by hydrogen from the B2O3‐CaO‐FeO melt in bubbled layer
Authors: Dmitriev Andrey N. , Vusikhis Alexander S. , Sitnikov Vladimir A. , Leontiev Leopold I. , Kudinov Dmitriy Z. 
Published: August 2008

AbstractStudy of the gas interaction process with the multicomponent oxide melt during barbotage with the purpose of testing the selective extraction possibility, is of interest from scientific and practical points of view. The solution of this problem within the scope of the complex decisions of the problem of rational resource development is of especial interest for the Urals, and for the Sverdlovsk region in particular.The processes mentioned above are heterogeneous ones and go through a number of sequential stages. Each stage can be limiting and can influence the overall process. However, despite the mechanism of the reaction its rate depends on the chemical composition of the gas contained in the bubbles that move in the melt. If the bubbles are in the melt for a long enough time, equilibrium is reached inside it and the process of gas interaction with melt is stopped. A model giving a qualitative description of the process of kinetics on the basis of thermodynamic equilibrium calculations has been developed by the authors. This model has been used for describing interaction between hydrogen and B2O3‐CaO‐FeO melt at various temperatures. This model has allowed us to analyze the process course and to consider temperature influence on such characteristics as melt component concentrations and their changes during process, the final gas composition, and other characteristics without any experiments.
Capillarity‐induced patterning of thin polymer films and related regular dewetting structures
Authors: Suh Kahp Y. 
Published: August 2008

AbstractWhen a thin polymer film is spin‐coated on a solid substrate and heated above its glass transition temperature (Tg) while in conformal contact with a patterned polydimethylsiloxane (PDMS) mold, capillarity forces the polymer melt to fill up the void space of the mold, thereby forming a negative replica of the polymer after mold removal. In this study, particular emphasis is given to the nodal dewetting phenomenon in a thin, laterally confined polymer film that sticks to a substrate. When heated above the glass transition temperature, the film dewets from the substrate through the generation of nodal waves, with the PDMS wall acting as a node. Various superposed waves were observed depending on the intrinsic period of dewetting and the confining width of the cavity.
The influence of Ag and Si additions on the electrochemical behavior in extruded Mg‐Zn alloys
Authors: Ben‐Hamu Guy , Eliezer Amir 
Published: August 2008

AbstractDevelopment of new wrought magnesium alloys for the automotive industry has increased in recent years, due to their high potential as structural materials for low density and high strength/weight ratio demands. However, the poor mechanical properties and low corrosion resistance of the magnesium alloys have led to a search for new kinds of magnesium alloys, for better strength, ductility, and high corrosion resistance. The main objective of this research is to investigate the corrosion behavior of new magnesium alloys: Mg‐Zn‐Ag (ZQ) and Mg‐Zn‐Si (ZS). The ZQ6X and ZS6X alloys were prepared using the hot extrusion method. AC and DC polarization tests were carried out on the extruded rods, which contain different amounts of silver or silicon.The microstructure was examined using optical and electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results showed that the silver addition decreased corrosion resistance. The addition of silicon also affected corrosion behavior. These results can be explained by the effects of alloying elements on the microstructure of Mg‐Zn alloys, such as grain size and precipitates caused by the change in precipitation, and by recrystallization behavior.
An attempt to improve the evaluation of mechanical material properties from the Axisymmetric Tensile Test
Authors: Gromada Magdalena , Mishuris Gennady , Öchsner Andreas 
Published: August 2008

AbstractThis paper deals with new analytical modeling of the classical tensile test with an axisymmetric sample and determining the yield stress of elasto‐plastic materials under the neck formation. Known for many years, classical Bridgman and Siebel‐Davidenkov‐Spiridonova's formulas provide certain errors, especially visible in the case of weakly hardening or ideal‐plastic materials. Accurate numerical simulations of the process allowed verification of the analytical results. Based on the numerical simulations, some modifications of the analytical models and their derivation have been proposed which enabled the elimination of the two most questionable classic assumptions. Comparison of new results with well‐known formulas shows that some progress is reached for small plastic deformations; however, for greater strain level further improvement is still advisable.
Excess oxygen at metal‐oxide interfaces—a review of the segregation process based on the current state of knowledge
Authors: Gegner Jürgen 
Published: August 2008

AbstractAccumulation or depletion of excess oxygen atoms at metal‐oxide interfaces, which can handily be controlled by adjusting the oxygen activity, leads to modifications of the atomic structure and chemical composition of the heterophase boundaries. The established atomistic model, which also explains changes of the macroscopic material behavior, interprets the process as interfacial oxygen segregation. Structurally necessary vacancies at terminating close‐packed oxide lattice planes serve as oxygen traps. These point defects are reversibly refillable with excess atoms. Experimental findings on oxygen‐controlled alterations of metal‐oxide interfaces obtained by electron energy loss spectroscopy, quantitative gas volume measurement,18O‐16O isotope exchange experiments, and the electrochemical hydrogen probe are compiled and valued with regard to the basic modeling assumptions. Thermodynamics data derived from volumetrically determined oxygen isotherms show that the chemisorption segregation process is energetically comparable with the formation of a two‐dimensional oxide layer of the metal component at the phase boundary. Subsequent hydrogen accumulation occurs by the development of hydroxide bonds. For palladium‐based nano‐oxide dispersion microstructures under practical process conditions, diffusion of bulk‐dissolved oxygen to the precipitates represents the rate‐controlling substep of interfacial segregation, which can thus be suppressed by shock quenching. The spatial arrangement of the embedded particles is characterized by quantitative transmission electron image analysis. For these palladium‐oxide materials, an adapted model of the kinetics of interfacial oxygen segregation is established. The simulations are compared with results of electrochemical measurements and cooling curves determined contactlessly by infrared pyrometry.
Creation of Shock‐Abrasion Resistance Build‐up Metal Using a Physicochemical Model of High‐Temperature Processes
Authors: Borodianskiy Konstantin , Mazurovsky Vladimir , Zinigrad Michael , Gedanken Aharon 
Published: August 2008

AbstractBuild‐up metal for shock‐abrasion resistance was the focus of this work, where the mathematical model of physicochemical high‐temperature processes developed by the authors in their previous works was used. A computer program based on the model permitted forecasting of the required chemical composition and structure of the build‐up metal.Flux‐cored wires were fabricated from a cold‐rolled ribbon (1008 steel) and filled with a powder mixture. Low carbon steel (A 516) was used as the base metal.The specimens were prepared by 3‐layered build‐up. The prepared specimens were tested using light microscopy, scanning electron microscopy (SEM), energy dispersive X‐ray analysis (EDS), hardness measurements, and shock‐abrasion resistance measurements.The results of the above‐mentioned tests confirmed the correct calculation of the model and the good shock‐abrasion resistance of the suggested build‐up metal.
Pressure Dependence of Exchange Parameters and Neel Temperature in La2CuO4
Authors: Fishman Anatolii Ya. , Mitrofanov Valentin Ya. 
Published: August 2008

AbstractMicroscopic mechanisms responsible for the observed pressure dependencies of the Neel temperature TN and parameters of isotropic and anisotropic exchange interaction in the orthorhombic antiferromagnet La2CuO4 are investigated. Within the framework of the Anderson microscopic theory of superexchange interaction, the expressions establishing interrelation between parameters of isotropic and anisotropic (both symmetric and antisymmetric) exchange interactions and by the structural parameters describing the Cu‐O‐Cu bonding angle and the Cu‐O bond length in La2CuO4 are obtained. Experimentally determined pressure dependencies of structural parameters by H. Takahashi et al., allow one to present pressure dependencies of exchange parameters and TN in an apparent form.
Simulation of Ni3Al‐based Alloy and Investment Casting Process of its Thin Wall Castings
Authors: Zhang Xi‐e , Li Shi‐qiong , Cao He‐li Luo, Xu , Feng Di , Li Shang‐ping 
Published: August 2008

AbstractIt is very difficult to produce thin wall complex castings of the Ni3Al‐based alloy by investment casting. Defects such as incomplete mold filling and hot tears appear commonly. In this paper, physical parameters of Ni3Al‐based alloy are obtained by experiments and simulations using JmatPro software. The calculation results of physical parameters are credible by comparing with test results and can be used in the pre‐processing of casting simulaton software ProCAST of thin wall castings. Gating and feeding system is optimized to decrease hot tearing tendentiousness and ensure filling ability according to casting simulation results.
Thermodynamic Modeling of Phase Equilibria in the WO3‐Zn System
Authors: Shubin Alexey B. , Shunyaev Konstantin Yu. 
Published: August 2008

AbstractThere are no alloys in the W‐Zn binary system. The combustion process in the WO3‐Zn powder mixture gives mainly metallic tungsten and zinc oxide. The ZnO in the product can be easily leached (e.g., with HCl), so that from stoichiometric quantities of reagents, one can obtain W powder of good purity.Here we investigated the phase equilibria for the WO3‐Zn system in the temperature range of 900‐1500 K. The inert component (Ar) was introduced into the system to change the pressure within the range of 0.1‐0.5 MPa.When the pressure is constant, the quantity of tungsten dioxide in the equilibrium mixture of components increases with rise in temperature, while the fraction of the zinc oxide decreases. The fraction of metallic tungsten in the mixture also decreases with temperature increase and becomes near zero at 1500 K and 0.1 MPa.Up to 1100 K, the output of tungsten is close to the limiting (stoichiometric) value in the whole considered pressure range (0.1‐0.5 MPa).
On the Mechanisms of Colloidal Particle and Vapor Bubble Aggregation in Liquid Flows
Authors: Bormashenko Edward , Pogreb Roman 
Published: August 2008

AbstractMechanisms of aggregation of micrometrically scaled colloidal particles and vapor bubbles are discussed. It is shown that when particles move in reference to the liquid, the attractive force induced by the flow may be greater than the capillary interaction. Such a situation is realized when capillary interaction is gravity driven, and particles float. For partial (weak) wetting situations, flow‐induced and capillary attractive forces may be comparable. If the wetting is good, it will play a decisive role in the realistically achievable values of the flow velocities. Hydrody‐namic interaction between particles may be of primary importance for sedimentation and fast dip‐coating‐induced aggregation.
The Theoretical Challenge Posed by Low‐Voltage Membrane Electroporation, Viewed from the Perspective of Continuum and Molecular‐Level Models
Authors: Partenskii Michael B. , Miloshevsky Gennady V. , Jordan Peter C. 
Published: August 2008

AbstractThe effect of applied voltage (V) or a membrane‐bound charge (q) on local thickness fluctuations (LTFs) in lipid bilayers is examined using the continuum approach. Ponderomotive forces, calculated from the linearized Poisson‐Boltzmann equation, reduce the electroelastic energy of LTFs quadratically with V and q. Combined with a significant increase in the apex field gradient and perturbation of lipid packing at large amplitude LTFs, this creates a driving force for instability resulting in water penetration, formation of pores, and membrane rupture. The estimated critical voltages for membrane electroporation are compared with the classical Crowley prediction and recent molecular dynamics (MD) simulations. Unsolved questions impeding a full understanding of low‐voltage breakdown are critically examined. Possible connections between MD results and the issue of negative capacitance and related instabilities at electrified interfaces are outlined.
Magnetization of Manganese Perovskites
Authors: Karpenko Boris V. , Falkovskaya Lyubov D. , Kuznetsov Alexandr V. 
Published: August 2008

AbstractTemperature dependence of spontaneous magnetization at a separate site in the compounds La1‐xCaxMnO3 (0 ⩽ x ⩽ 1) is investigated in the molecular field approximation using a homogeneous model for the magnetic sub‐lattice with allowance for the Heisenberg superexchange and double exchange between nearest neighbors. Unlike with the usual magnets having one type of magnetic ions, in this case there appears a system of equations with two unknowns, mean spins of ions Mn3+ and Mn4+. In the vicinity of the ordering temperature, this system can be solved analytically and the expression for the ordering temperature can be obtained as well. To find the temperature dependence of magnetization in the whole temperature range, we used the exact expression for the double exchange operator containing spin operators under the square root. The numerical solutions were found in this case.
Fabrication of Thin Oriented Organic Layers and Micropatterns by Zone Casting
Authors: Tracz Adam , Masirek Sylwia , Klos Marcin 
Published: August 2008

AbstractZone casting—a special solution processing method for obtaining highly ordered continuous layers of soluble organic materials—can also be applied for fabricating patterned layers. In this method, solution is continuously supplied onto a substrate that is withdrawn at a controlled rate, and the solvent evaporates from the surface of a meniscus formed between a flat nozzle and the substrate. Due to the gradient of a solute concentration, its solidification proceeds within the narrow zone localized in the meniscus. In this way solute molecules can be self‐assembled at surfaces into different anisotropic nanostructures (columns, rods, lamellae, or microcrystals) uniaxially aligned parallel to the substrate. Under some conditions various phenomena like dewetting, fingering instability, stick‐slip motion, etc., come into play, leading to various periodic perturbations in the film deposition. Examples of continuous and patterned layers of different materials such as low molecular weight (semi)conductors, chromophores, discotic molecules, and block copolymers, which can successfully be processed using this technique, are shown. Typical layers obtained through this method are shown to have good properties as active layers in field effect transistors.