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71.
de Souza NC Caetano W Itri R Rodrigues CA Oliveira ON Giacometti JA Ferreira M 《Journal of colloid and interface science》2006,297(2):546-553
The influence of small amounts of bovine serum albumin (BSA) (nM concentration) on the lateral organization of phospholipid monolayers at the air-water interface and transferred onto solid substrates as one-layer Langmuir-Blodgett (LB) films was investigated. The kinetics of adsorption of BSA onto the phospholipid monolayers was monitored with surface pressure isotherms in a Langmuir trough, for the zwitterionic dipalmitoylphosphatidyl ethanolamine (N,N-dimethyl-PE) and the anionic dimyristoylphosphatidic acid (DMPA). A monolayer of N,N-dimethyl-PE or DMPA incorporating BSA was transferred onto a solid substrate using the Langmuir-Blodgett technique. Atomic force microscopy (AFM) images of one-layer LB films displayed protein-phospholipid domains, whose morphology was characterized using dynamic scaling theories to calculate roughness exponents. For DMPA-BSA films the surface is characteristic of self-affine fractals, which may be described with the Kardar-Parisi-Zhang (KPZ) equation. On the other hand, for N,N-dimethyl-PE-BSA films, the results indicate a relatively flat surface within the globule. The height profile and the number and size of globules varied with the type of phospholipid. The overall results, from kinetics of adsorption on Langmuir monolayers and surface morphology in LB films, could be interpreted in terms of the higher affinity of BSA to the anionic DMPA than to the zwitterionic N,N-dimethyl-PE. Furthermore, the effects from such small amounts of BSA in the monolayer point to a cooperative response of DMPA and N,N-dimethyl-PE monolayers to the protein. 相似文献
72.
Nara J Kajiyama H Hashizume T Suwa Y Heike S Matsuura S Hitosugi T Ohno T 《Physical review letters》2008,100(2):026102
The formation mechanism of one-dimensional Si islands on a H/Si(001)-(2x1) surface is studied using scanning tunneling microscopy/spectroscopy and first-principles calculations. We observed that one-dimensional islands that are made from dimer chains are formed at the initial growth stages similar to the bare Si(001) surface. It is found that the number of odd-numbered dimer chains is larger than that of even-numbered dimer chains. We propose the growth processes of the two types of growth edges to explain the observation. 相似文献
73.
An ionic pseudopotential for semiconductors is proposed, which consists of a set of continuous exponential functions. Introduced damping and amplitude parameters into the pseudopotential are to be treated as adjustable. The most important features of the proposed pseudopotential is that (1) it has no sharp cut-off parameter for the core-repulsion and (2) it is continuous and has continuous derivatives to arbitrary order. The proposed pseudopotential is applied to Si and the adjustable parameters are determined so as to be consistent with the Si crystal empirical pseudopotential of high quality by taking a valence electron dielectric screening effect into account. The effectiveness of the proposed ionic pseudopotential is discussed by (1) comparing the calculated ionic energy levels of Si with experiments, (2) checking the consistency between the ionic and crystal pseudopotentials for Si, and so on. 相似文献
74.
R.S. Chakrawarthy B.S. Nara Singh R.G. Pillay 《The European Physical Journal A - Hadrons and Nuclei》1998,3(1):5-8
High spin states in 108In have been established upto ∼ 8 MeV in excitation energy and to a tentative spin of (23−). The data were obtained by in-beam γ-ray spectroscopy using the reaction 93Nb(19F, p3n)108In at a beam energy of 86 MeV. Four sequences of dipole bands and a normal rotational band of E2 γ-transitions have been placed
in the level scheme.
Received: 16 June 1998 相似文献
75.
Travain SA de Souza NC Balogh DT Giacometti JA 《Journal of colloid and interface science》2007,316(2):292-297
Polyaniline (PAni) thin films were deposited onto BK7 glass substrates using the in situ deposition technique. The control of the time and the aniline concentration in the PAni polymerization reaction on the film deposition allowed us to prepare films with different thickness, down to approximately 25 nm. The film growth process was monitored by measuring the UV-vis spectra and the AFM height profiles of the film surface. The curves of adsorption kinetics were analyzed with the Avrami's model, yielding an exponent n=3, thus indicating nucleation of spheroids at the initial stages of polymerization that grow through a diffusion process. AFM images of the surface height profiles corroborate this hypothesis, with spheroids growing with no preferred orientation during the in situ deposition. 相似文献
76.
The adsorption of thiolates with various tail molecules on the Au(111) surface has been investigated by first-principles calculations. We have considered six typical thiolate molecules, that is, methylthiolate, ethylthiolate, ethylenethiolate, acetylenethiolate, benzenethiolate, and thiophenethiolate. It is found that these thiolates exhibit little difference in their stable adsorption geometries. They are adsorbed at the bridge site with being significantly tilted from the surface normal. The adsorption energy of thiolate on Au, on the other hand, largely varies depending on the type of tail molecule, and is linearly proportional to the binding energy of thiolate with H. We discuss the tail molecule dependence in terms of the bonding environment around the C atom connected to the head S atom. 相似文献
77.
Yoshitaka Nara Kazuya Morimoto Tetsuro Yoneda Naoki Hiroyoshi Katsuhiko Kaneko 《International Journal of Solids and Structures》2011,48(7-8):1130-1140
In order to ensure long-term stability of structures in a rock mass, the study of time-dependent fracturing is essential. The influences of the surrounding environmental conditions and rock fabric on subcritical crack growth in sedimentary rocks in air are yet to be clarified, while the nature of subcritical crack growth in igneous rocks has been studied well. In this study, the influences of temperature and relative humidity on subcritical crack growth in Berea sandstone, Shirahama sandstone and Kushiro sandstone were investigated in air. The load relaxation method of Double Torsion (DT) testing method was used to measure both crack velocity and stress intensity factor under a controlled temperature and relative humidity.Results show that the change of the crack velocity at a given stress intensity factor was unclear when the temperature increased under a constant relative humidity in air. On the other hand, we show that the crack velocity increased by several orders of magnitude when the relative humidity increased threefold or fourfold under a constant temperature at a given stress intensity factor. This increase is much larger than that expected from the conventional concept based on the theory of stress corrosion. It is therefore necessary to consider the additional mechanisms for subcritical crack growth in sandstone. The increase of the crack velocity was larger for sandstone which contained larger amount of clays. We conclude that subcritical crack growth in sandstone in air is affected remarkably by the relative humidity and the amount of clays in rock. 相似文献
78.
Yuki Nara 《Surface science》2007,601(22):5170-5172
Geometrical structures of the Sn-adsorbed Cu(0 0 1) surfaces are studied with scanning tunneling microscopy. There are four phases in the Sn coverage range between 0.2 and 0.5 mono-atomic layer (ML). On the basis of the observed atomic images in this range, we propose structural models for the phases with 0.33 and 0.375 ML of Sn. All the phases consist of embedded Sn atoms in the Cu surface, forming two-dimensional surface alloy structures. On the surface with ∼0.4 ML of Sn, a novel one-dimensional structure is observed. 相似文献
79.
Differential scanning calorimetry (DSC) was used to investigate entrapped water in poly(o-methoxyaniline) (POMA) in powder form. Two endothermic peaks were attributed to removal of water molecules that were adsorbed with distinct energies. By obtaining thermograms at various heating rates, we succeeded in applying Kissinger's approaches to estimate activation energies for the water adsorbed. The values obtained were ca. 25 and 53 kJ/mol, which correspond to H-bonding interactions, probably at the amine and imine centers of POMA, respectively. 相似文献
80.
B. S. Nara Singh A. N. Steer D. G. Jenkins R. Wadsworth P. J. Davies R. Glover N. S. Pattabiraman T. Grahn P. T. Greenlees P. Jones R. Julin M. Leino M. Nyman J. Pakarinen P. Rahkila C. Scholey J. Sorri J. Uusitalo P. A. Butler M. Dimmock D. T. Joss J. Thomson C. J. Lister B. Cederwall B. Hadinia M. Sandzelius 《The European physical journal. Special topics》2007,150(1):147-148
We present a study of low-spin states in 74Rb and 78Y
using the new technique of Recoil Beta Tagging.
This yielded new information on 74Rb and has provided the first evidence
for non-isomeric T= 1 states in 78Y. 相似文献