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91.
S. Krishna Prasad Geetha G. Nair Gurumurthy Hegde Uma S. Hiremath C. V. Yelamaggad 《Liquid crystals》2004,31(9):1265-1270
We report a novel method of confining a photoconducting liquid crystalline material using a polymer templating approach. The attractive feature of this approach is that the magnitude of the photocurrent of the photoconducting material does not diminish, i.e. it is unaltered by the polymer matrix. The results are compared with another method of encapsulation that was recently reported and wherein the photoconductivity decreases upon having the photoconducting material in the polymer matrix. The difference in the behaviour between the two methods is explained using a nanophase segregation model. The method described is particularly suitable for creating patterned photoconductors. 相似文献
92.
An ultraviolet photoelectron spectrometer for the study of free atoms and molecules has been designed and fabricated with
indigeneous components. The spectrometer consists of a 100 mA HeI discharge lamp, 180° hemispherical electron energy analyser
(127 mm mean dia) and electron multiplier ratemeter electron detection systems. The resolution of the spectrometer is 90 meV/and
the intensity of N2 (5σ) band is 105 c/sec. The sample inlet and the collision chamber can be heated to 500 K so that solids of low vapour pressure can be studied.
Typical spectra of molecules recorded with the instrument are shown.
Contribution No. 373 from the Solid State and Structural Chemistry Unit. 相似文献
93.
The coadsorption of PH3 with H2, D2, O2 and H2O on Rh(100) has been studied using temperature programmed desorption (TPD), Auger electron spectroscopy (AES) and low energy electron diffraction (LEED). The adsorption and molecular desorption of PH3 is not affected by preadsorbed H2, D2 and O2. Preadsorbed PH3 blocks H2 desorption sites while postdosed PH3 displaces H2 (D21) from the Rh(100). When D2 and PH3 are coadsorbed, no D appears in desorbed phosphine. Preadsorbed O2 reduces the amount of H2 desorption (from PH3 decomposition) and increases the H2 desorption temperature. There is also some reaction between O(a) and H(a) to form water. Preexposure to H2O decreases the extent of PH3 adsorption and of PH3 decomposition. 相似文献
94.
95.
Ajay K. Bose M.S. Manhas J.M. van der Veen S.S. Bari D.R. Wagle V.R. Hegde Lalitha Krishnan 《Tetrahedron letters》1985,26(1):33-36
Enantiospecific synthesis of variously substituted cis-β-lactams can be achieved by the annelation of Schiff bases from optically active ketal aldehydes derived from D-threonine. Similar annelation of Schiff bases from the triphenylsilyl ether of D-threonine ester and cinnamaldehyde leads to cis-β-lactams with high diastereofacial selectivity. 相似文献
96.
Krishnamoorthy G Webb SP Nguyen T Chowdhury PK Halder M Wills NJ Carpenter S Kraus GA Gordon MS Petrich JW 《Photochemistry and photobiology》2005,81(4):924-933
Hydroxy and methoxy perylene quinones are synthesized in an attempt to isolate the essential spectroscopic and biological features of light-induced antiviral agents such as hypericin and hypocrellin. Unlike their naturally occurring counterparts, these synthetic quinones bear the carbonyl, hydroxyl, and methoxy groups in the "bay region." The hydroxy and methoxy compounds have rich absorption spectra with broad features in the visible (approximately 450-800 nm) and relatively more intense and narrow features at wavelengths < or = 350 nm. High-level ab initio quantum mechanical calculations assign the features in the absorption spectra to electronic transitions from S0 to S2 and to higher-lying electronic states. The calculations indicate that in the ground state the trans dihydroxy isomer is 12.5 kcal/mol lower in energy than the cis dihydroxy isomer and is thus the only species present. The lowest-energy trans methoxy ground state isomer and the lowest-energy cis methoxy ground state isomer are found to be degenerate. An additional cis methoxy isomer 6.3 kcal/mol higher in energy than the global minimum is assumed to contribute to the spectrum and is also considered. Finally, the synthetic compounds exhibit similar light-induced antiviral activity to each other, but significantly less than that of hypericin. 相似文献
97.
Bharathi Alagar Muthumani Narayanan Anbalagan Krishnamoorthy 《Transition Metal Chemistry》1997,22(6):586-588
The ground- and excited-state reactivities of the [Cr- (en)3]3+ (en=1,2-diaminoethane) and [Cr(NCS)6]3− ions in a polyacrylamide
(PAA) environment are reported. The aquation kinetics of these complexes has been studied to identify the effect of added
PAA with varying molecular weight. Aquation of the complexes in aqueous acid containing PAA yielded the respective substituted
products. The macromolecule in solution was found to decrease significantly the rate of ligand replacement. Similarly, photolysis
of the cationic and anionic complexes in water–PAA mixtures revealed a decrease in aquation quantum yield. Possible explanations
for the decrease in reaction rates and quantum yields are discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
98.
99.
A rapid and highly sensitive silver staining method, originally developed for the detection of proteins, was slightly modified to detect nucleic acids in polyacrylamide gels. The second exons of the histocompatibility antigen HLA-DQA 1 and DQB 1 genes were selectively amplified from genomic DNA by the polymerase chain reaction (PCR). Digestion of the PCR products by endonucleases, followed by their size-separation on polyacrylamide gels and visualization by silver staining, allowed us to define the HLA-DQ alleles of the genomic DNA. The intensity of staining of digested PCR-amplified DNA is linear from at least 8 to 18 ng for fragments of lengths ranging from approximately 40 to 200 bp. Thus, silver staining in combination with PCR and allele-specific restriction fragment length polymorphism provides a simple, safe, and rapid method for accurate definition of HLA-DQ alleles at the nucleotide level in the clinical typing laboratory. 相似文献
100.
A complete solution is established to the problem of characterizing all situations in which a linear combination C = c
1
A+c
2
B of an idempotent matrix A and a tripotent matrix B is k-idempotent. As a special case of this, a set of necessary and sufficient conditions for a linear combination C = c
1
A+c
2
B to be k-idempotent when A and B are idempotent matrices, is also studied in this paper. 相似文献