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101.
Environmental scanning electron microscopy was used to investigate the dynamic meniscus growth at a cantilever in contact with a substrate. The meniscus was observed to take many minutes to reach an equilibrium state. The observed growth rate is similar to initial patterning rates observed from dip-pen nanolithography and suggest that the meniscus growth may be the rate-limiting step in initial pattering rates. 相似文献
102.
The reflectance spectra of ion implanted SiO2 glasses has been measured from 5000 cm−1 to 400 cm−1. The silica was implanted with Ti, Cr, Mn, Fe, Cu and Bi to nominal doses ranging from 1×1015 ions/cm2 to 1.2×1017 ions/cm2 at an energy of 160 keV and currents of approximately 2.6 μA/cm2. Changes in the intensity of the 1232 cm−1 and 1015 cm−1 vibrational modes are attributed to changes in the intermediate range order (IRO) and to changes in the concentration of non-bridging oxygen (NBO) defects in the implanted layer. These changes are ion and dose dependent. The differing effects on IRO and NBO are attributed to the chemical interaction of the implanted ions with the substrate. 相似文献
103.
Gas chromatographic separation of tobacco alkaloids 总被引:1,自引:0,他引:1
104.
In this study, the effect of zinc impurity on the organic high explosive pentaerythritol tetranitrate (PETN) single crystal has been investigated with optical microscopy and ex situ atomic force microscopy (AFM). The optical images show that the crystal shape has a transition with a predictable trend from long crystal to compact one as the zinc concentration is increased. Also, the 2‐dimentional (2‐D) growth hillocks are observed clearly on (110) face with contact AFM. The crystal growth occurs on monomolecular steps generated by 2‐D nucleation and followed by layer‐by‐layer expansion, and the macro‐steps formed onto the surface before spreading laterally as step bunches. The zinc ions are incorporated in growth steps as the zinc concentration is increased. The mechanism of inorganic impurity on molecular crystallization growth is still unclear. However, the incorporation of impurities may significantly affect growth kinetics of defect structure, and the bulk properties of molecular crystals. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
105.
We use a new configuration-based version of linear response theory to efficiently solve self-consistent mean field equations relating an effective single particle potential to the induced density. The versatility and accuracy of the method is illustrated by applications to dewetting of a hard sphere solute in a Lennard-Jones fluid, the interplay between local hydrogen bond structure and electrostatics for water confined between two hydrophobic walls, and to ion pairing in ionic solutions. Simulation time has been reduced by more than an order of magnitude over previous methods. 相似文献
106.
107.
Using fast confocal microscopy we image the three-dimensional dynamics of particles in a yielded hard-sphere colloidal glass under steady shear. The structural relaxation, observed in regions with uniform shear, is nearly isotropic but is distinctly different from that of quiescent metastable colloidal fluids. The inverse relaxation time tau(alpha)(-1) and diffusion constant D, as functions of the local shear rate gamma*, show marked shear thinning with tau(alpha)(-1) proportional to D proportional to gamma*(0.8) over more than two decades in gamma*. In contrast, the global rheology of the system displays Herschel-Bulkley behavior. We discuss the possible role of large scale shear localization and other mechanisms in generating this difference. 相似文献
108.
Colin L. Weeks Hyunil Jo Brandon Kier William F. DeGrado Thomas G. Spiro 《Journal of Raman spectroscopy : JRS》2012,43(9):1244-1249
Nitriles introduced into peptides and proteins can serve as useful vibrational spectroscopic probes, because the nitrile C ≡ N stretch is well isolated from backbone and sidechain vibrational bands. Aromatic nitriles offer large νC ≡ N absorption intensity in infrared spectra and resonance enhancement in Raman spectra with ultraviolet excitation. We report the ultraviolet resonance Raman spectra of cyanophenylalanine attached to cysteine, through linkage reactions that are applicable to cysteine residues in proteins. Excitation profiles are reported, and the νC ≡ N detection limit is estimated to be 5 µ m . The band position is sensitive to solvent polarity and especially to strong H‐bonding. The derivatization of mastoparan X peptide at introduced cysteine residues demonstrated the effectiveness of a cyanophenylcysteine probe in reporting the lowered environmental polarity when the peptide was incorporated into liposomes. For an asymmetrical cyanophenyl derivative, 2‐CBCys, the intensity ratio of asymmetric and symmetric ring modes, ν8b and ν8a, was found to respond to solvent polarity and not to H‐bonding. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
109.
110.
Ranganathan M Dougherty DB Cullen WG Zhao T Weeks JD Williams ED 《Physical review letters》2005,95(22):225505
Supported nanoscale lead crystallites with a step emerging from a noncentered screw dislocation on the circular top facet were prepared by rapid cooling from just above the melting temperature. STM observations of the top facet show a nonuniform rotation rate and shape of the spiral step as the crystallite relaxes. These features can be accurately modeled using curvature driven dynamics, as in classical models of spiral growth, with boundary conditions fixing the dislocation core and regions of the step lying along the outer facet edge. 相似文献