Sodium Chloride Surface Research Articles

Effectof Pkc Stimulation on Sodium Chloride Cotransporter Function and Surface Expression in Mammalian Cells

Restricted accessAbstractFirst published March 2007Effectof Pkc Stimulation on Sodium Chloride Cotransporter Function and Surface Expression in Mammalian CellsB. Ko, L. Joshi, […], L. Cooke, M. Musch, and R.S. Hoover+2-2View all authors and affiliationsVolume 55, Issue 2https://doi.org/10.1177/108155890705500249

Conformational analysis and the binding sites of nitrilotriacetamide: A computational study

AbstractThe conformational analysis of nitrilotriacetamide has been carried out computationally, at both the semi‐empirical AM1 and density functional theory (DFT) (B3LYP/6‐31+G*) levels of theory. The lowest‐energy conformation predicted with the Monte Carlo search method, using the AM1 model, has two amide functionalities aligned on the same side; however, the DFT calculations at B3LYP/6‐31+G* predicted the global minimum with all three acetamide functionalities on the same side in the gas phase. In the aqueous phase, the DFT results predicted the orientations of amides similar to that of the reported crystal structure. The rotation barriers to transition to different low‐energy conformers of nitrilotriacetamide are lower in energy (5.0 kcal/mol) in water. The molecular electrostatic isopotentials (MESP) generated for the selected conformers at DFT level show that the nitrilotriacetamide could interact more effectively with the sodium chloride surface than that of its monomeric unit nitrilomonoacetamide. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007

Deposition of nanostructured metal coatings on the modified silicon surfaces in the magnetoplasma compressor

The process of formation of nanostructured metal coatings on silicon and sodium chloride surfaces exposed to compression plasma flow has been studied. To analyze microstructure, morphology, elemental and phase composition of near-surface layer, methods of scanning electron microscopy (SEM), energy dispersive X-ray (EDX) microanalysis, and transmission electron microscopy (TEM) were used. The coating obtained looks like a monolayer consisting of spherical particles, a few to 200 nm in size, bonded to each other. These particles cover both plane surface areas and cylindrical structures formed in the course of plasma treatment. The coating thickness correlates with sizes of particles.

HRTEM and EELS Studies of L1<SUB>0</SUB>-Ordered FePt nano-Clusters on MgO Films Prepared Below 673 K

Three kinds of FePt-MgO granular films were prepared by a vacuum successive deposition of MgO, Pt, Fe and MgO on a cleaved surface of sodium chloride below 673 K. Their microstructures, electronic structures and magnetic properties were studied by high-resolution transmission electron microscopy (HRTEM), electron energy-loss spectroscopy (EELS) and measurement with a superconducting quantum interference device (SQUID) magnetometer. The TEM observations and selected area electron diffraction patterns revealed that the samples mainly consist of few nm-sized FePt clusters embedded in MgO films with L1 0 -ordered structure and c-axis perpendicular to the film surface. Size effect on the stability of L1 0 phase in the FePt nano-clusters was directly observed in [MgO/Fe(0.38nm)/Pt(0.30nm)/MgO] and the critical size of the transition from L1 0 to A1 phase was estimated as around 2 nm, that can be considered as smaller than effective size for the transition from ferromagnetism to superparamagnetism. Coercivity of [MgO/Fe(1.0nm)/Pt(0.8nm)/MgO] was 1.2 x 10 5 A/m. The Fe-L 2 , 3 white-line ratios of the present samples measured by EELS were about 4.0, independently on the incident direction of electron beam. The higher white-line ratio may be attributed to their high-spin state by a change of 3d-band structure owing to the hybridization of d-bands between Fe and Pt atoms.

Impact, Trapping, and Accommodation of Hydroxyl Radical and Ozone at Aqueous Salt Aerosol Surfaces. A Molecular Dynamics Study

Collisions of the gaseous hydroxyl (OH) radical and ozone (O3) with the surfaces of sodium chloride or iodide solutions, as well as with the surface of neat water, were investigated by molecular dynamics simulations. The principal intent was to answer atmospherically relevant questions concerning the trapping and accommodation of the OH and O3 species at the surface and their uptake into the bulk solution. Although trapping is substantial for both species, OH adsorbs and absorbs significantly better than O3. Most of the trapped O3 molecules desorb from the surface within 50 ps, whereas a significant fraction of OH radicals remains at the interface for time intervals exceeding 100 ps. The aqueous surface has also an orientational effect on the OH species, favoring geometries with the H atom pointing toward the aqueous bulk. The effect of the dissolved salt on the trapping efficiency is minor; therefore, most likely, atomic ions solvated in aqueous aerosols do not act as strong scavengers of reactive gases ...

The deduction of fine structural details of reverse osmosis hollow fiber membranes using surface force–pore flow model

In order to elucidate the relationship between the dope extrusion shear rate and membrane performance, sodium chloride transfer through the asymmetric cellulose acetate reverse osmosis hollow fiber membranes is modeled, allowing fine details of the fiber structure to be deduced from the NaCl-H2O rejection characteristics. The structural information such as the pore size radius and skin thickness of the active layer deduced from the sodium chloride separation experimental data and surface force-pore flow model (SF-PF) is then used to interpret the relationship between the rheological conditions during spinning and membrane performance. The modeling results revealed that increased extrusion shear rate would decrease both pore size and thickness of the active layer, thus increasing the separation performance of the RO hollow fiber membranes.

Femtosecond laser ablation from sodium chloride and barium fluoride

The microscopic processes leading to material removal from sodium chloride (1 0 0) and barium fluoride (1 1 1) surfaces upon irradiation with near infrared femtosecond laser pulses are investigated using time-of-flight mass spectroscopy of charged particles. A pump–probe excitation setup permits us to follow the dynamic development of the charged particle emission on a femtosecond time scale. We find that the emission of electrons as well as of positive ions is mostly governed by the transient light intensity during the impact of the laser pulse. However, the correlation signal exhibits asymmetric shoulders, unexpectedly.

Electron Beam-Induced Chemical Reactions Of Single Crystal Calcium Floride By Time - Resolved EELS

Abstract Using parallel beam illumination, electron beam-induced structural transformation has been studied as radiation damages for decades. Recently, however, more attention may need to be paid to beam-induced chemical transformation which happens under illumination by a finely focused beam. Such a small probe is often used in analytical electron microscopy, particularly the core-electron energy loss spectroscopy (EELS). Since the signal for the spectroscopy is very weak long radiation is required and makes the induced chemical reactions happen. Therefore, without attentions to the reactions, the acquired data could lead to misinterpretation of specimen properties. In the present study, using a single crystal calcium fluoride (CaF2), we demonstrated by time-resolved EELS that radiation with a nanometer electron probe could induce chemical reactions between the specimen and the typical residual gases in a microscope column. The thin films of CaF2 were fabricated by vaporizing flakes of single crystal CaF2 with an electron beam and by dissolving the vapors onto a (001) surface of sodium chloride (NaCl) heated at 300°C.

Angle-resolved auger electron emission from ion-bombarded NaCl surface

Characteristic electron emission spectra obtained from ion-bombarded sodium chloride surface are distinctly different and more complex than such spectra from metallic sodium. The spectra for sodium halides have been explained recently in a context of the collisional deexcitation model in which the core excited sodium ion colliding with a halogen anion captures an electron which activates autoionizing deexcitation channels. However, a controversy has arisen whether the Auger deexcitation process takes place inside the solid or in vacuum above the surface. In the present work we report on the angular dependence of the Na Auger electron line positions and intensities. The source atom energies and basic characteristics of their angular distributions are derived from the experimental data. An interpretation of the observed angular-dependent line shifts is given in terms of the Doppler effect. The results indicate strongly that the Auger deexcitation processes occur on sodium atoms ejected directionally above the surface due to direct knock-off collisions with primary ions.

A helium atom scattering study of the structure and dynamics of a Xe monolayer on NaCl(001)

The adsorption of xenon on the sodium chloride (001) surface has been studied using high-resolution helium atom scattering. From the temperature dependence of the specular intensity in the range between 27 and 70 K under isobaric conditions the heat of adsorption of the Xe monolayer was determined to be Eads=19.2±2 kJ/mol. At monolayer coverage, helium atom diffraction measurements reveal that a strained quasi-hexagonal superstructure is formed, which differs from the well-known hexagonal structure of the Xe bulk, and has a c(10×2) symmetry. The perpendicular frustrated translation vibrational energy was measured with helium atom time-of-flight spectroscopy to be 2.5 meV and showed an avoided crossing with the NaCl surface Rayleigh mode. A further dispersive mode of the monolayer has been assigned to a longitudinal in-plane mode of the Xe layer. As found for Xe monolayers on several low index copper surfaces the best fit radial force constant for this mode is a factor of four smaller than deduced from the Xe–Xe gas-phase potential.

Self-organized Fe nanowire arrays prepared by shadow deposition on NaCl(110) templates

Iron nanowire arrays have been grown by shadow deposition on a self-organized grating template produced by annealing the sodium chloride (110) surface. The typical wire size as measured using transmission electron microscopy is 45 nm×13 nm×10 μm. The typical wire array period is 90 nm. The magnetic properties were dominated by a strong in-plane shape anisotropy. The hysteresis loops examined by magneto-optical Kerr effect measurements indicated coherent switching, even though the individual wires were isolated from one another.

Time-resolved high-resolution electron microscopy of structural transformation in nanocrystalline ZnO films

Mechanical properties of polycrystalline materials become anomalous when the grain size and grain boundary length decrease to nanometer scale. For example, ductility and toughness increase significantly in nanometer-grained ceramics (nanocrystalline ceramics). Ductility increases due to appearance of fine-grained-superplastic deformation. Grain boundary migration and interface migration are fundamental processes of the superplastic deformation. Structural transformation of fine grains is a factor which limits the toughness in polycrystalline ceramics because the transformation relaxes internal strain. The behavior of grain boundaries and interfaces, such as diffusion bonding and Czochralski-type crystal growth at ambient temperature, can be analyzed by a time-resolved high-resolution electron microscopy (TRHREM) developed by Kizuka et al.,In the present study, grain boundary migration and successive transformation of crystal structure in nanocrystalline ZnO were investigated by TRHREM.Zinc oxide was vacuum-deposited on air-cleaved (001) surfaces of sodium chloride at 200°C. TRHREM was carried out at room temperature using a 200-kV electron microscope (JEOL, JEM2010) equipped with a high sensitive TV camera and a video tape recorder.

Time-resolved high-resolution electron microscopy of grain migration process in MgO films

High-resolution electron microscopy (HREM) has been employed intensively to analyze the atomic structures of grain boundaries and interfaces having two dimensional structures inside polycrystalline and composite materials. Furthermore time-resolved HREM (TRHREM) is required to analyze the behavior of grain boundaries and interfaces at atomic scale. The grain boundary migration, which is a typical grain boundary behavior, is a fundamental process relating to structural stability of polycrystalline materials. The mechanism of the migration has been still unknown.In the present study, the variation of atomic arrangement at the grain boundary migration of a MgO [001]Σ5 boundary was analyzed by TRHREM.Magnesium oxide polycrystalline films were prepared by vacuum-deposition on air-cleaved (001) surfaces of sodium chloride at 300°C. TRHREM was carried out at room temperature using a 200-kV electron microscope (JEOL, JEM2010) equipped with a high sensitive TV camera and a video tape recorder. The spatial resolution of the system was 0.2 nm at 200 kV and the time resolution was 1/60 s. Electron beam density was 30 A/cm2.

Time-resolved high-resolution electron microscopy of nanometer-scale electron beam processing of PbTe films

Various kinds of nanometer scale processings are required to produce advanced materials, for example, nano-structured electric devices. Electron beam processing at nanometer scale using STEM and TEM, such as drilling and line-writing, is recently interested as a most useful method. Details of structural change during the processing should be elucidated at atomic resolution in order to establish the processing. In the present work we have processed lead telluride (PbTe) films with nanometer electron beam in a high-resolution transmission electron microscope and in-situ observed the variation of atomic arrangements during the processing.PbTe of 99.99% was vacuum-deposited on air-cleaved (001) surfaces of sodium chloride at room temperature. Time-resolved high-resolution electron microscopy was carried out at room temperature using a 200-kV electron microscope (JEOL, JEM2010) equipped with a high sensitive TV camera and a video tape recorder. The spatial resolution of thesystem was 0.2 nm at 200 kV and the time resolution was 1/60 s. Electron beam irradiation density was 120 A/cm2 at the processing and the observation.

The structure and dynamics of CO2 on NaCl(001) studied by helium atom scattering

The structure and dynamics of physisorbed carbon dioxide on in situ cleaved single crystal sodium chloride surfaces was studied by means of elastic as well as inelastic helium atom scattering. At Tsurface=80–83.5 K the diffraction patterns indicate a commensurate (2×1) monolayer superstructure on the (001) plane of the substrate, the unit cell containing a glide plane. This is in agreement with results obtained from low energy electron diffraction and infrared spectroscopy. In time-of-flight experiments single phonon low-energy loss and gain features were observed which can be attributed to acoustic and optical modes. Two higher-energy features are probably due to the first combination modes observed by helium atom scattering so far. The growth of solid CO2 adsorbed on NaCl(001) was also studied.

Temperature programmed desorption from electron irradiated sodium chloride

We study temperature programmed desorption of sodium and chlorine from an electron irradiated sodium chloride (100) surface. In this experiment, the sodium chloride crystal is irradiated with 500 eV electrons. After the electron beam is turned off, the crystal is heated and desorption of the alkali atoms is observed. This delayed desorption of sodium is analyzed using fractional order desorption equations. The results clearly show that the desorption is not a first order process. The data are interpreted in terms of a thick layer of sodium forming on the surface.

Influence of process variables on the drying of potato slices

SummaryInvestigation of the effects of varying air velocity, slice thickness, and pre‐treatment with sodium chloride solutions and surface active agents on drying potato slices indicated that the drying occurred entirely in the falling rate period and was controlled by the mechanism of liquid diffusion. The rate of drying, and therefore the diffusion coefficients, increased with the addition of sodium chloride and surface active agents. Diffusion coefficients were also influenced by air velocity and slice thickness, suggesting that the rate of drying of potato slices is controlled by a combination of internal and external resistances.

Dynamics of Cluster-Surface Collisions

The structure, energetics, and dynamics of shock conditions generated in a nano-cluster upon impact on a crystalline surface are investigated with molecular-dynamics simulations for a 561-atom argon cluster incident with a velocity of 3 kilometers per second onto a sodium chloride surface. The "piling-up" shock phenomenon occurring upon impact, coupled with cascades of energy and momentum transfer processes and inertial confinement of material in the interior of the cluster, creates a transient medium lasting for about a picosecond and characterized by extreme local density, pressure, and kinetic temperature. The nano-shock conditions and impulsive nature of interactions in the newly formed compressed nonequilibrium environment open avenues for studying chemical reactivity and dynamics catalysed via cluster impact.

Growth of Al-Mn, Al-Cu-Fe and Al-Fe quasicrystalline films prepared by vacuum deposition

Thin films of Al-Mn, Al-Fe and Al-Cu-Fe quasicrystalline films are prepared by a successive deposition technique in a vacuum onto air-cleaved sodium chloride surfaces at substrate temperatures of 220–350°C. The growth of the quasicrystals is found as grains of 20–50 nm in size, the five-fold axis being perpendicular to the film surface and the two-fold axis of the quasicrystal parallel to [110] directions of the (111) orientated aluminum film. For the Al-Fe and Al-Cu-Fe system, the rotation of the five-fold axis around the two-fold axes by around 10° can be recognized. Below about 10 at % of manganese or iron content, a coexistence of aluminum and the quasicrystalline grains is observed. High resolution electron microscopy is applied to the quasicrystal films, by which the vertex model with a decoration in Penrose tiling is suggested.

Explaining the anomalous orientation of epitaxial gold on sodium chloride

It is difficult to produce parallel epitaxy of gold on cleveed sodium chloride surfaces, (001)Au | (001)NaCl, unless some substrate surface defects have been created. When such epitaxy does occur the observed orientation 〈110〉Au | 〈110〉NaCl involves a 28% misift, whereas if rotated 45° to 〈110〉Au | 〈110〉NaCl the misfit would be only 2%. A detailed calculation of cluster-surface interaction potential energies for gold clusters forming in NaCl are used to explain this observation. When clusters nucleate on the defect structures they are initiated in the poor registry orientation. Subsidiary maxima in the potential energy vs orientation curve prevent subsequent rotation to the lowest energy configuration.