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991.
Fluorous chemistry, involving the use of a fluorous label for the functionalization of a substrate and a fluorous solvent for extraction of the functionalized substrate, is shown to be effective in solubilizing gold and CdSe nanoparticles in a fluorous medium, through phase transfer from an aqueous or a hydrocarbon medium. While these nanoparticles were functionalized with a fluorous thiol, single-walled carbon nanotubes and ZnO nanorods could be solubilized in a fluorous medium by reacting them with a fluorous amine. Fluorous chemistry enables the solubilization of the nanostructures in the most nonpolar liquid medium possible. 相似文献
992.
Let k be any infinite perfect field. Let E be a vector bundleover a smooth projective curve defined over k. We prove thatE admits a connection if the degree of every indecomposablecomponent of E is zero. This has been proved (when k = ) inM. F. Atiyah [2] and A. Weil [7]. 相似文献
993.
Fluorescence emission spectroscopy have been used to investigate the effects of electrolytes on the excited state intramolecular
charge transfer (ICT) reaction in 4-(1-azetidinyl)benzonitrile (P4C) in very dilute to concentrated electrolyte solutions
of ethyl acetate (EA), acetonitrile (AN) and ethanol (EtOH). In the limit of very low electrolyte concentrations, the reaction
rate (=1/τ
rxn, τ
rxn being the reaction time) is found to decrease with increasing electrolyte concentration, the extent of decrease being the maximum in EA and the minimum in AN. At moderate
to higher electrolyte concentrations, however, the rate increases upon further addition of electrolyte. The observed non-monotonic
electrolyte concentration dependence of rate is believed to occur due to a novel interplay between friction and solvation
experienced by the photo-excited reactant in solution. Moreover, the long time decay constant and amplitude of the bi-exponential
decay of the time resolved fluorescence emission intensity also show a significant electrolyte concentration dependence which
corroborates the relevant steady-state results.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users. 相似文献
994.
The Reaction of phenylmercury(II) acetate with salicylaldehyde morpholine N-thiohydrazone (H2smth) and 2-hydroxyacetophenone morpholine N-thiohydrazone (H2apmth) in dry ethanol under gentle refluxing condition form light yellow complexes [PhHg(Hsmth)] (1) and [PhHg(Hapmth)] (2) involving formation of Hg-S bond from the thiol form of the ligands after deprotonation of the SH proton. The structures of the complexes as determined by X-ray crystallography shows that the complex (1) has a distorted T-shaped geometry while the complex (2) adopts familiar linear coordination geometry. Complex (2) has two independent molecules comprising the asymmetric unit. Both the complexes form two-dimensional supramolecular assemblies due to a combination of weak intermolecular Hg····π and Hg····Hg interactions. The Hg····π and Hg····Hg distances are 3.937 and 4.0216(10) Å, respectively, possibly indicating weak mercuriophilic interactions. The luminescent properties of the complexes in solution and in the solid state at room temperature are also described. 相似文献
995.
We consider multi-dimensional nondegenerate diffusions with invariant densities, with the diffusion matrix scaled by a small >0. The o.d.e. limit corresponding to =0 is assumed to have the origin as its unique globally asymptotically stable equilibrium. Using control theoretic methods, we show that in the ↓0 limit, the invariant density has the form ≈exp(−W(x)/2), where the W is characterized as the optimal cost of a deterministic control problem. This generalizes an earlier work of Sheu. Extension to multiple equilibria is also given. 相似文献
996.
Indranil Biswas 《Bulletin des Sciences Mathématiques》2009,133(5):477-483
We show that the fundamental group-scheme of a separably rationally connected variety defined over an algebraically closed field is trivial. Let X be a geometrically irreducible smooth projective variety defined over a finite field k admitting a k-rational point. Let {En,σn}n?0 be a flat principal G-bundle over X, where G is a reductive linear algebraic group defined over k. We show that there is a positive integer a such that the principal G-bundle is isomorphic to E0, where FX is the absolute Frobenius morphism of X. From this it follows that E0 is given by a representation of the fundamental group-scheme of X in G. 相似文献
997.
RF-excited fast axial flow CO2 lasers in kilowatt regime are presently being used for various new scientific applications in addition to laser material
processing because of its versatility and superior beam quality. We have indigenously developed a compact 2 kW RF-excited
fast axial flow CO2 laser with moderate beam quality. In this paper the key design features of the laser and the associated high power capacitively
coupled RF excitation technique are discussed in detail. Operational characteristics of this system are described along with
the experimental findings. 相似文献
998.
Pulsed laser-assisted removal of particulates from substrates has decided advantages over the conventional methods of cleaning.
Experiments conducted with loose contamination on metal and transparent dielectric surfaces proved conclusively the dominant
role played by the absorption of the incident radiation by the surface towards the generation of the cleaning force as against
the absorption in the particulates alone. Further, the presence of transparent/semi-transparent particulates on a metal surface
was found to result in an increased absorption of the incident radiation by the substrate. This effect, identified as field-enhanced
surface absorption was found to increase with reduction in the average particulate size. 相似文献
999.
Influence of quantum confinement on the photoemission from superlattices of optoelectronic materials
D. De A. Kumar S.M. Adhikari S. Pahari N. Islam P. Banerjee S.K. Biswas S. Bhattacharya K.P. Ghatak 《Superlattices and Microstructures》2010
We study the photoemission from quantum wire and quantum dot superlattices with graded interfaces of optoelectronic materials on the basis of newly formulated electron dispersion relations in the presence of external photo-excitation. Besides, the influence of a magnetic field on the photoemission from the aforementioned superlattices together with quantum well superlattices in the presence of a quantizing magnetic field has also been studied in this context. It has been observed taking into account HgTe/Hg1−xCdxTe and InxGa1−xAs/InP that the photoemission from these nanostructures increases with increasing photon energy in quantized steps and exhibits oscillatory dependences with the increase in carrier concentration. Besides, the photoemission decreases with increasing light intensity and wavelength, together with the fact that said emission decreases with increasing thickness exhibiting oscillatory spikes. The strong dependences of the photoemission on the light intensity reflects the direct signature of light waves on the carrier energy spectra. The content of this paper finds six applications in the fields of low dimensional systems in general. 相似文献
1000.
Tomar G Shankar V Shukla SK Sharma A Biswas G 《The European physical journal. E, Soft matter》2006,20(2):185-200
The instability, rupture, and subsequent growth of holes in a thin Jeffreys-type viscoelastic film under the influence of
long-range van der Waals force are investigated using both linear stability analysis and nonlinear numerical solutions. The
linear stability analysis of full governing equations valid for arbitrary wave numbers shows that although fluid rheology
does not influence the dominant length scale of the instability, it significantly affects the growth rate. It is shown that
neglect of inertia and solvent dynamics results in a nonphysical singularity in the growth rate beyond a critical value of
relaxation time. We further carry out numerical simulations of a set of long-wave, nonlinear differential equations (also
derived in Rauscher et al., Eur. Phys. J. E 17, 373 (2005)) governing the evolution of the free surface. The nonlinear simulations, in their domain of validity, confirm
the results of the linear analysis. Interestingly, results from nonlinear simulations further show that both for Newtonian
and viscoelastic liquids, the shape and the dewetting dynamics of a hole are identical when examined in terms of a rescaled
time which depends on rheological parameters. Thus, viscoelasticity of Jeffreys type merely accelerates the growth rate, without
however affecting the important morphological characteristics. 相似文献