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941.
We consider the model of the one-dimensional cookie random walk when the initial cookie distribution is spatially uniform
and the number of cookies per site is finite. We give a criterion to decide whether the limiting speed of the walk is non-zero.
In particular, we show that a positive speed may be obtained for just three cookies per site. We also prove a result on the
continuity of the speed with respect to the initial cookie distribution.
相似文献
942.
Gowravaram Sabitha Kurra Yadagiri Martha Bhikshapathi Gajangi Chandrashekhar Jhillu Singh Yadav 《Tetrahedron: Asymmetry》2010,21(20):2524-2529
The construction of the C32–C42 fragment of etnangien is described using a desymmetrization strategy generating five stereogenic centers from a bicyclic lactone. Another notable feature includes the use of the Sharpless asymmetric epoxidation to generate a stereogenic center at C40. 相似文献
943.
This paper presents several applications of the PHI-TEC II that are not commonly associated with adiabatic calorimeters but which have proved to be extremely valuable. These include simulation of a deep oil well for enhanced oil recovery, isothermal calorimetry of a semibatch reaction, catalyst research using flow through reactors (both plug flow and CSTR) with controlled feeds of high pressure liquid and gas.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
944.
Nd2O3-SiO2 binary oxide was prepared by solgel technique using tetra-ethoxysilane and neodymium nitrate as precursor materials and HCl as a catalyst. The prepared samples were subjected to heat treatment in the temperature range from 600 to 1100 °C for different time duration. Characterization of heat treated samples was carried out by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The effect of sintering temperature and time on structural changes of Nd-doped silica has been discussed. The sample sintered at 1100 °C for 12 h shows the formation of monoclinic Nd2O3 nanocrystallites in silica matrix with average grain size ∼18 nm. 相似文献
945.
Rakesh Kumar Singh P. Senthilkumaran Kehar Singh 《Optics and Lasers in Engineering》2009,47(7-8):831-841
Tight focusing of linearly and circularly polarized vortex beams is studied in the presence of third-order spherical aberration, using vectorial Debye–Wolf integral. Results for total intensity distribution are presented for both polarizations. In addition, results for x-, y-, and z-polarization components are presented for the circularly polarized beam. Generation of longitudinal optical vortex in the tightly focused left circularly polarized beam has also been demonstrated by plotting its phase distribution. Compensation for the effect of spherical aberration has been studied in the presence of defocusing. Effect of aberration on the dark core of a tightly focused azimuthally polarized beam is also investigated. 相似文献
946.
The reaction of 1,8-diamino-3,6-diazaoctane and diethyl malonate in dry methanol yielded a 13-membered macrocycle. Complexes
of the type [Ln(tatd)Cl2 (H2O)3]Cl [LnIII=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy; tatd=1, 5, 8, 11-tetra-azacyclotridecane-2,4-dione] have been synthesized by template condensation.
The complex [La(tatd)Cl2 (H2O)3]Cl in methanol was reacted with lanthanide chlorides to yield the trinuclear complexes of type [2{La(tatd)Cl2(H2O)3}LnCl3]Cl2 [LnIII=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy]. The chemical compositions of mono and trinuclear complexes have been established on the
basis of analytical, molar conductance, electrospray (ES) and fast atom bombardment (FAB) mass data. In mononuclear complexes
the Ln3+ ion is encapsulated by four ring nitrogens and in trimetallic complexes the exo-carbonyl oxygens of two mononuclear units
coordinate to the Ln3+ ions resulting in a polyhedron around the lanthanide ions. Thus the macrocycle is bonded in a tetradentate fashion in the
former complexes and hexadentate in the latter. The coordination number nine around the encapsulated Ln3+ and seven around the exo-oxygen bonded Ln3+ ions are established. The symmetry of the ligand field around the metal ions is indicated from the emission spectra. 相似文献
947.
S. V. Singh A. N. Thakur O. P. Singh S. C. Kumar Aqil Ahmad 《Indian Journal of Physics》2009,83(3):375-381
PbSrWO4 and PbBaWO4 have been synthesised by the solid state reaction technique XRD patterns show them to be tetragonal. Dielectric constant
(K/) and Dielectric loss (K
//) of PbSrWO4 and PbBaWO4 have been measured at 1 kHz in the temperature range of 300 to 1050 K. The log K/ vs T as well as log K
//
vs T plot of PbSrWO4 and PbBaWO4 shows rapid increase of dielectric constant above 590 K and 640 K, respectively. 相似文献
948.
A facile method for the construction of an immunoconjugate which displays targeting ligands, such as antibody fragments, with a high density is reported. For this purpose, we synthesized a novel trifunctional crosslinking reagent. By the use of this reagent, ligands targeting the specific cell can be displayed on the surface of the drug carrier with a high density. In this study, we display HER2 (human epidermal growth‐factor receptor‐2) binding ligands on branched polyethylenimine (PEI), which can form polyplexes with plasmid DNA. Kinetic analysis of the binding to the extracellular domain of HER2 show the PEI displaying a high density of ligands binds to the target more strongly compared to the PEI displaying ligands at a low density. The increased density of HER2 ligands displayed on the gene carrier contributes to the improved transfection efficiency. This approach can be applied to other drug delivery systems, including liposome, micelle, and so on. 相似文献
949.
950.
A diethanolamine stabilized precursor sol has been utilized for studying the effect of sol aging and annealing temperature
on key properties of TiO2 films. X-ray diffraction investigations have shown increased crystallite size in the films as a function of both sol aging
and the thermal treatment. Fourier transform infrared studies have elucidated that cleavage of the bond involving diethanolamine
and the alkoxide in the films requires high temperature annealing treatment upon the use of aged sol for the deposition of
the films. Multiple step chronoamperometry has shown the ion storage capacity of the films increases as a function of sol
aging, with the highest extent of Li ion insertion being obtained for films produced from as-prepared and aged sols and subsequently
annealed at, 300 and 350 °C, respectively. Films with excellent optical quality were obtained. Ellipsometry revealed that
the refractive indices of the films vary from 1.67 to 2.02. The highest thickness obtained in these films was nearly 900 nm.
The bandgaps of the films for both direct and indirect transitions decreased as a function of precursor sol’s aging. In addition,
although the indirect bandgap values have shown a decrease with increasing annealing temperature, the direct bandgap values
reveal a slight increase as a function of annealing temperature. 相似文献