bluuebunny/crossref_metadata_2025_split huggingface dataset:
The R-Phase Transformation in the Ti-Ni Shape Memory Alloy and its Application
Authors: Ohkata I. , Tamura H. 
Published: April 2011

ABSTRACTWe discuss a comprehensive design approach of Ti-Ni alloy coil springs and introduce a new application of the R-phase transformation. In order to attain high cyclic performance, one must understand the two relationships between design parameters and material characteristics and between material characteristics and cyclic performance. Metallurgical parameters and coil spring dimensions play an important role as design parameters in the former relationship. High cyclic performance of an actuator is closely related to the suppression of the monoclinic martensite. Transformation temperatures and their stress dependence is of primary importance as material characteristics in the latter relationship. A thermostatic mixing valve, which is the latest application of the R-phase transformation in Japan is then discussed as a new type of a shape memory alloy actuator. The R-phase transformation is employed to achieve not only a long cycle life but a linear operation with the set temperature to continuously control the mixing ratio of hot and cold water. This is achieved by changing the total length of the two-way actuator in a linear manner with the set temperature. The linear characteristic is satisfied between 35–50°C by optimizing thermomechanical treatment and the dimensions of Ti-Ni and biasing coil springs.
Cooling Rate Dependence of Fatigue Life Time (Nf) of Cu-Al-Ni Alloy Prepared by Liquid-Quenching
Authors: Mori K. , Tanaka Y. , Furuya S. , Okada T. , Komatsuzaki K. , Nishi Y. 
Published: April 2011

ABSTRACTSince the fatigue life time is a serious problem of the Cu-Al-Ni alloy, it is difficult to apply for practical use. The authors have investigated the influence of the cooling condition of liquid-quenching on fatigue property. The liquid-quenching is performed by a piston-anvil apparatus. It is easy to control the solidification condition. The fatigue life time increases with increasing the cooling rate. The long life time is due to the small grain size, the small volume of γ1' phase, the low density of lattice defects and the low transformation temperature.
Enhanced Mechanical Properties of Smart Polymer-Matrix Hybrid Composite by Shape Memory Effect
Authors: Izui H. , Hamada K. , Ogawa K. , Taya M. , Inoue K. 
Published: April 2011

ABSTRACTNew smart hybrid composite with TiNi shape memory alloy (SMA) fiber as reinforcement is designed to be composed of TiNi fiber and carbon/epoxy (CFRP) composite. One-dimensional composite modeling is utilized to evaluate residual stresses of the smart composite generated by shape memory effects. The modeling indicated that the tensile strength of TiNi/CFRP composite is improved due to the shape memory effect of TiNi fiber for both parallel and perpendicular configurations of TiNi fiber with respect to the direction of carbon fiber. Modeling also shows the tensile strength is increased with increasing both volume fraction of TiNi fiber and amount of prestrain.
Computational Models for Multicomponent Diffusion in Polymeric Materials
Authors: Rossi G. , Samus M. A. 
Published: April 2011

ABSTRACTSituations where a polymeric material is exposed to a solvent mixture so that the different components within the mixture can diffuse into the polymer are common both in industrial applications and in biological processes. Often one of the components is taken up preferentially and its presence affects the diffusion properties of the remaining components. The problem of accounting for processes of this type has not been dealt with in a systematic way. This may in part be due to the difficulty of characterizing experimentally the separate diffusion behavior of the various components: data of this kind are now becoming available for simple binary mixtures. In order to model this class of problems, a lattice model involving a polymer matrix (M) and two diffusing components (A and B) has been introduced. The Monte Carlo evolution of the system has been examined for different values of the local A–M, B–M and A–B interactions. These results shed light on the microscopic origin of selective uptake.
Scaling for the Coalescence of Microfractures before Breakdown
Authors: Zapperi S. , Ray P. , Stanley H. E. , Vespignani A. 
Published: April 2011

ABSTRACTWe study the behavior of fracture in disordered systems close to the breakdown point. We simulate numerically both scalar (resistor network) and vectorial (spring network) models with threshold disorder, driven at constant current and stress rate respectively. We analyze the scaling of the susceptibility and the cluster size close to the breakdown. We observe avalanche behavior and clustering of the cracks. We find that the scaling exponents are consistent with those found close to a mean-field spinodal and present analogies between the coalescence of microfractures and the coalescence of droplets in a metastable magnetic system. Finally, we discuss different experimental conditions and some possible theoretical interpretations of the results.
Ac Response of Heterogeneous Materials: A Numerical Study
Authors: Rodriguez A. A. , Valbuena J. 
Published: April 2011

ABSTRACTThe ac and dc electrical properties of composite materials are studied using hierarchical lattices. First we show that the hierarchical model can correctly account for the main scaling properties of critical percolative structures. Then we study the effect of potential disorder by assuming that the microscopic conductances are distributed according to a power law distribution function. We find that in the limit of strong disorder, the predictions are in qualitative agreement with reported experimental measurements.
Influence of sheet electron beam irradiation (SEBI) on water wettability of hydroxy apatites for artificial bone
Authors: Kawano J. , Izumi H. , Oguri K. , Tonegawa A. , Kawai T. , Ochi M. , Nishi Y. 
Published: April 2011

ABSTRACTAn influence of sheet electron beam irradiation (SEBI) on the wettability is investigated of the hydroxy apatite (HAP) [Ca10(PO4)6(OH)2]. The wettability is one of the important factors to control bio-compatibility. The SEBI is homogeneously performed by an electrocurtain processor. The temperature of the sample is below 323 K just after the irradiation. The wettability is evaluated by measuring the wet angle θ in a drop of water. The SEBI increases the wettability. Based on rate process, the influence of SEBI on wettability is discussed. Using the SEBI, we can precisely control the surface condition of HAP.
Adhesion of Soft Biological Shells controlled by Bending Elasticity and Macromolecular Networks
Authors: Simson R. , Albersdörfer A. , Sackmann E. 
Published: April 2011

AbstractWe present an interferometrie technique allowing reliable measurements of bending modulus κ, membrane tension Σ and adhesion energy W of cells crawling on substrates. All three parameters are important for cell locomotion and reflect the local balance of attractive and repulsive forces between cell and substratum as well as the internal coupling of cell membrane and the underlying cytoskeleton. Mutants of the Dictyostelium ameba lacking an important cytoskeletal protein, Cortexillin, exhibited a markedly reduced bending modulus and adhesion energy as compared to wild type Dictyostelium. In addition, experiments with model membrane systems suggest that the combination of attractive and repulsive forces results in a local clustering of receptors mediating cell adhesion.
Driven Granular Media and Dissipative Gases: Correlations and Liquid-Gas Phase Transitions
Authors: Williams D.R.M. 
Published: April 2011

ABSTRACTWe study a simple model of a granular material or powder where the particles are excited by an external noise source and dissipate energy by inelastic collisions. Due to the inelastic collisions between particles there is an effective interaction between them. In one dimension this leads to long-range correlations between the particles in a gas phase despite the absence of long-range forces between the particles. In two dimensions the dissipative effects cause a very sharp liquid-gas phase transition at which the susceptibility has a pronounced peak.
Separation of DNA Using Ferrofluid Array Electrophoresis
Authors: Mayer Pascal , Bibette Jerôme , Viovy J. L. 
Published: April 2011

ABSTRACTWe present a new method for electrophoretic separation of DNA, Ferro fluid Array Electrophoresis (FAE). The method uses a stabilized suspension of an hydrophobic ferrofluid in aqueous buffer as the separating medium. When this suspension is placed in a slab cell and submitted to a magnetic field perpendicular to the slab plane, it organizes into a regular array of columns with micron-sized spacing. DNA migrating in this maze leads to size-fractionation. Resolution of lambda phage (48.5 kbp) and T4 (140 kbp) DNA molecules in 30 mn is achieved. The motion of individual DNA molecules during FAE is observed using fluorescence videomicroscopy, and the molecular mechanisms responsible for separation are discussed in the light of recent computer simulations. During migration, large DNA molecules temporarily wrap around the impenetrable ferrofluid columns. They disengage by slippage, like a rope on a pulley, and the dependence of the disengagement time upon DNA size is responsible for the size-fractionation.
DNA End-to-End Distance Change Due to Divalent Counterion Condensation Studffid by Pulse Gel Electrophoresis
Authors: Li Anzhi Z. , Huang Haiyan , Marx Kenneth A. 
Published: April 2011

ABSTRACTThe conformation change of DNA fragments due to divalent counterion condensation onto DNA was investigated by pulse gel electrophoresis, and interpreted by gel models (Reptation and Henry model) and Manning's counterion condensation theory. The measured mobility reductions μ/μ0 of λ-DNA-Hind III fragments, ranging from 23.13 to 2.027 kilobase pairs, due to interaction with divalent cation Mg2+ (1–400 μμ), and Ca2+(0–40 μM) in tris-borate buffer were well fit by Manning's Counterion Condensation (CC) theory. We observed the normalized mobility reduction to be shifted by a small amount Δ(μ/μ0) relative to the CC prediction value. Δ(μ/μ0) is a function of DNA length, and the ion environment (divalent concentration C2 and ionic strength). The ‘shift’ phenomena only occurred close to where C2 began dominating the counterion binding, a condition described by the monovalent/divalent cation isocompetition point. Combining our observation with theoretical considerations, we conclude that the divalent counterion condensation changes the DNA fragments' conformation, resulting in an end-to-end distance decrease which is molecular weight dependent. The effect was enhanced by an increase of divalent ion concentration and a decrease of the ionic strength.
A Study of Impacting Droplets of an Emulsion or Surfactant Solution on Solid Substrates
Authors: Vignes-Adler M. , Prunet-Foch B. , Legay F. , Mourougou N. 
Published: April 2011

ABSTRACTCoating of solid surfaces with uniform, thin liquid films occurs in many industrial processes. A common process consists of spraying some liquids or emulsions on a freshly created solid surface. In this context, we have investigated the impact of a single droplet of various emulsions and surface-active solutions on a solid substrate using a high frequency fluorescent visualization technique (1 picture every 0.25 ms). Whatever the materials in presence, the drop spreads and then retracts under the action of inertia and capillarity respectively. Inertia induces spreading and generates a peripheral rim which is unstable to fingering. Then contact line instabilities appear under the form of festoons with pure liquids which are damped with surface-active solutions and amplified with emulsions. When the adsorption kinetics of the surfactant is slow, the equilibrium surface tension is not restored during the duration of the experiment and the drop can bounce back.
Hysteresis Phenomena in Nanoconfinements: Density Functional Theory and Experiments
Authors: Neimark A.V. , Ravikovitch P.I. 
Published: April 2011

ABSTRACTHysteresis phenomena are observed in many nanoporous environments during adsorption/desorption isothermal quasiequilibrium cycles. A non-local DFT model has been developed for predicting adsorption/desorption isotherms in nanopores of different geometries in the wide range of pore sizes (0.5–10 nm) based on given intermolecular fluid/fluid and fluid/solid potentials. Depending on the confining geometry and the intermolecular potentials two types of hysteresis phenomena are occurred: capillary condensation/evaporation that implies volume filling of pores with a liquid-like matter, and layering adsorption/desorption that implies sequential step-wise formation of adsorption layers. It is shown that the DFT model qualitatively describes these phenomena and is in a reasonable quantitative agreement with some of the experiments.
Structure and Phase Transitions in Partially Confined Smectic Liquid Crystals
Authors: Martinez-Miranda L. J. , Shi Yushan , Kumar Satyendra 
Published: April 2011

ABSTRACTWe present the results of an X-ray scattering study on partially confined smectic-A (layered) LC films. This partial confinement is achieved by placing the LC material inside the open grooves of a glass grating. Samples prepared in this manner are confined in the direction perpendicular to the gratings. Samples in which the LC is contained entirely inside the grooves develop an induced molecular tilt, which results in a compression of the smectic layers. The molecular tilt varies as the amount of the LC material increases, eventually forming a thin overlayer film above the gratings. As the thickness varies, a second region develops in the films. The layer spacing in this region is close to the bulk layer spacing. This structural evolution is coupled to a variation in the nematic-to-smectic-A phase transition temperature of the samples from the bulk. In addition, the nature of the phase transition is driven first order. The effects of partial confinement on a sm-C* LC film is discussed briefly.
Translational Diffusion of Liquids Confined in Nanopores
Authors: Korb J.-P. , Whaley M. , Bryant R. G. 
Published: April 2011

ABSTRACTWe present a theory of nuclear spin relaxation and experiments to probe the microdynamics of polar solvents at the surface of calibrated microporous glass beads. The theory is tested using the magnetic field dependence of the proton spin-lattice relaxation rate recorded with a field-switched magnetic relaxation dispersion spectrometer.
Broad-Band Dielectric Spectroscopy of Liquid Crystals Confined in Random and Cylindrical Pores
Authors: Sinha G.P. , Aliev F.M. 
Published: April 2011

ABSTRACTUsing dielectric spectroscopy in the frequency range 0.1 Hz-1.5 GHz, we investigated the influence of confinement on the dynamic properties of polar nematic liquid crystals (LC) dispersed in porous matrices with randomly oriented, interconnected pores as well as in parallel cylindrical pores with different, pores sizes. The confinement has a strong influence on the dielectric properties of LC which resulted in the appearance of a low frequency relaxational process (f≤ 10 KHz) absent in bulk and a strong modification of modes due to the molecular rotation around short axis and librational motion. The differences between bulk and confined behavior are: (a) - the dielectrically active modes in confined LC are not frozen even at temperatures about 20 degrees below the bulk crystallization temperature; (b) - in the temperature range corresponding to the anisotropie phase in pores,lnτ, where τ is the relaxation time corresponding to the molecular rotation around short axis, is not a linear function of 1/T and there is an evidence for smectic type order formation at sufficiently low T; (c) - the retardation factorg= τ/τisis ≃ 1.5, where as the typical value ofgin bulk nematic liquid crystals is ≃ 4; (d) - smooth and small changes inTat phase transition in pores suggest that the “isotropie” phase of LC in pores is not bulk like isotropie phase with complete disorder in molecular orientations, and some degree of orientation order still persists.
Relaxation Phenomena and Thermodynamics of Liquids at Very High Pressures
Authors: Oliver W. F. 
Published: April 2011

ABSTRACTComplex liquid glass-forming systems ranging from those composed of simple molecules to polymer melts and amorphous polymers have been studied extensively as a function of temperature resulting in a basic understanding of liquid-state dynamics and glass transition phenomenology as these systems are supercooled to the vitreous state. An important aspect of this problem that remains largely unexplored, and that is relevant to the topic of this symposium, involves liquid-state dynamics and vitrification (as well as crystallization) in the regime of high pressure and high density. We describe work on “fragile” to “intermediate strength” simple organic glass-forming liquids where both temperature (T) and pressure (P) are varied. Diamond anvil cells are used to achieve pressures exceeding 10 GPa. Several optical and light scattering techniques are used to explore both static and dynamic properties of these systems. High-pressure Brillouin scattering enables us to model the longitudinal relaxation time in these systems as well as their equations of state. These can now be refined by direct measurements of the pressure dependence of the glass transition, Tg(P). Finally, we summarize depolarized light scattering studies which allow us to compare both the isobaric and isothermal evolution of structural (α) and fast (β) relaxation processes.
Temperature-Dependent Dynamics of Microconfined Cs2
Authors: Loughnane B. J. , Farrer R. A. , Deschenes L. A. , Fourkas J. T. 
Published: April 2011

ABSTRACTFemtosecond optical-heterodyne detected Raman-induced Kerr effect spectroscopy (OHD-RIKES) has been used to study the reorientational dynamics of CS2 in microporous glasses over a wide range of temperatures. Microconfinement is shown to affect the behavior of the liquid at all the temperature studied. The results are interpreted in terms of a two-state model of the confined liquid.
Instability and Frontal Breakup in Super-Meniscus Films
Authors: Kataoka Dawn E. , Troian Sandra M. 
Published: April 2011

ABSTRACTSurface tension gradients created by a nonuniform temperature distribution in athin liquid film can force vertical spreading beyond the equilibrium meniscus [1]. Experiments designed to probe the flow behavior of super-meniscus films have shown that the leading edge can either spread uniformly with complete surface coverage or become corrugated and breakupinto long slender rivulets. We show that within linear stability analysis, both the conditions for unstable flow and the most unstable wavelength compare favorably with recent experiments reported in the literature.
NMR Experiments on Molecular Dynamics in Nanoporous Media: Evidence for Lévy Walk Statistics
Authors: Kimmich Rainer , Zavada Tatiana , Stapf Siegfried 
Published: April 2011

ABSTRACTField-cycling 1H and 2H NMR relaxometry and field-gradient 1H NMR diffusometry were applied to polar and nonpolar liquids filled into porous glasses and fineparticle agglomerates (SiO2, ZnO, TiO2, globular proteins). The orders of magnitude of the length scales of the pore spaces ranged from 100 to several 102 nm. Pronounced differences of the spin-lattice relaxation dispersion for “weak” (nonpolar) and “strong” (polar) adsorption were found. In the latter case, the correlation times of the adsorbate orientation are up to eight orders of magnitude longer than in bulk. Trans-lational diffusion in liquid surface layers was directly studied with the aid of field-gradient NMR diffusometry in systems where the free liquid was frozen. The spin-lattice relaxation dispersion can be explained on the basis of reorientations mediated by translational displacements (RMTD) of adsorbate molecules on the surfaces. Thisprocess appears to be enhanced by a Levy walk mechanism so that the propagator adopts the form of a Cauchy distribution. The evaluated surface correlation functions are characterized by surface correlation lengths in the same order as the pore diameters, that is, up to three orders ofmagnitude larger than the length scale of dipolar interaction.
Gas Transport in Sol-Gel Derived Porous Carbon Aerogels
Authors: Reichenauer G. , Fricke J. 
Published: April 2011

ABSTRACTDue to their high electrical conductivity, their large specific surface area and their high porosity sol-gel derived nanoporous carbons are promising materials for electrodes, e.g. in water desalination systems or fuel cells. In order to optimize their properties with respect to these applications information is needed about transient and steady state transport through the interconnected pores.Dynamic gas expansion and time resolved permeation measurements allow to determine the relevantquantities, i.e. the permeability, the ratio of gas phase to surface diffusion and the volume of dead end pores along with the tortuosity.Experimental data on nanoporous carbons of different density are presented. All samples investigated were prepared via pyrolysis of resorcinol formaldehyde aerogels. The measurements were performed with different gases below 0.1 MPa.
Spectroscopie Studies of Confined Molecules Under Shear
Authors: Soga Iwao , Dhinojwala Ali , Cho Yoon-Kyoung , Granick Steve 
Published: April 2011

ABSTRACTWe introduce two new techniques with the sensitivity to measure spectroscopie properties of confined molecules under shear. One concerns rheo-optics of fluids in micron-sized gaps. The experimental approach consists in applying periodic shear motion to fluid films confined between parallel plates separated by controllable film thickness from 0.1 to 100 micrometers. A key aspect is the concurrent ability to perform spectroscopie experiments (infrared or dielectric spectroscopy, or x-ray or neutron spectroscopy) of these fluids during flow.The second technique consists in flow field experiments of polymer adsorption and orientation. The experimental approach is to produce one-directional shear, at rates up to 104 sec−1, past adsorbed polymer layers of thickness less than 0.01 micrometers. The selective augmentation of vibrational modes oriented preferentially along the chain backbone is then used to probe chain orientation in the direction of flow in a laminar flow field.
Search for Explaining the Staebler-Wronski Effect
Authors: Fritzsche H. , Az Tucson 
Published: April 2011

ABSTRACTFor twenty years we searched to understand the Staebler-Wronski effect (SWE). New results continue to emerge which invalidate prior interpretations. Recent evidence shows that the SWE is not associated with impurities. Long-range hydrogen diffusion is ruled out because the SWE occurs with comparable efficiency between 400K and the lowest temperatures. Nonradiative geminate recombinations might be important since high fields reduce the SWE significantly. It disappears when the bandgap or the photon energy falls below a critical value. The creation of a metastable density of dangling bond defects has been considered to be its sole manifestation. However, there is mounting evidence for light-induced structural changes which extend throughout the material. The weak bond breaking model emerges as the only viable explanation of the SWE if the expected spatial correlation between defects and hydrogen is destroyed by subsequent recombination events. The SWE is reduced by a favorable microstructure and low hydrogen content. It is suggested that defect pairs have larger recombination coefficients than isolated defects.