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71.
The electronic spectra of CrO2?4 ions embedded in cesium halide lattices show two well defined bands due to dipole allowed transitions along with some weak bands due to forbidden transitions. All the above bands are interpreted in terms of transitions within molecu ar orbital levels using the Ballhausen and Liehr scheme. It is observed that superposed on the electronic transitions there is a vibrational fine structure which arises due to the coupling between the electronic transitions and the totally symmetric stretching frequency of the ion. IR absorption spectrum of Analar grade CsI :CrO2?4 shows seven lines, whereas Specpure CsI :CrO2?4 shows five lines. The above spectra are interpreted on the basis of different local symmetries of CrO2?4 ions in the lattice. 相似文献
72.
73.
W. A. Sokalski S. Roszak P. C. Hariharan Joyce J. Kaufman 《International journal of quantum chemistry》1983,23(3):847-854
A modified scheme for SCF interaction energy decomposition has been proposed where the nonphysical basis set superposition error (BSSE ) has been corrected by means of the counterpoise method. A new procedure to separate the exchange and induction energy terms free of nonphysical BSSE has been tested in the case of the H2O dimer. The first order BSSE appears to be non-negligible for strong hydrogen bonded complexes. In addition the scheme allows separation of the long-controversial charge-transfer contribution within the induction term, which has been considerably overestimated in previous studies. 相似文献
74.
Oligonucleotides are synthesized on, and cleaved from, a solid phase support (6) using the o-nitrobenzyl intramolecular photochemical redox reaction. The yields of isolated oligonucleotides relative to yields obtained using conventional hydrolytic cleavage vary between 67% and 82.5%. Synthesis of oligonucleotides using phosphoramidites that do not contain N-benzoyl protecting groups enables one to photolytically cleave the biopolymers in good yields using a commonly available UV irradiation source. Tritium labeling indicates that less than 3% thymidine.thymidine photodimers are formed during photolytic cleavage of polythymidylates from 6 using a transilluminator. No UV-induced damage is detected via HPLC analysis of enzymatically digested oligonucleotides that were obtained following photolytic cleavage from 6. 相似文献
75.
Highly Luminescent Heterostructured Copper‐Doped Zinc Sulfide Nanocrystals for Application in Cancer Cell Labeling 下载免费PDF全文
Huixiang Ang Dr. Michel Bosman Dr. Ramesh Thamankar Muhammad Faizal B. Zulkifli Dr. Swee Kuan Yen Anushya Hariharan Dr. Thankiah Sudhaharan Dr. Subramanian Tamil Selvan 《Chemphyschem》2016,17(16):2489-2495
The structural characteristics of the seed‐mediated synthesis of heterostructured CuS–ZnS nanocrystals (NCs) and Cu‐doped ZnS (ZnS:Cu) NCs synthesized by two different protocols are compared and analyzed. At high Cu dopant concentrations, segregated subclusters of ZnS and CuS are observed. The photoluminescence quantum yield of ZnS:Cu NCs is about 50–80 %; a value much higher than that of ZnS NCs (6 %). Finally, these NCs are coated with a thin silica shell by using (3‐mercaptopropyl)triethoxysilane in a reverse microemulsion to make them water soluble. Cytotoxicity experiments show that these silica‐coated NCs have greatly reduced toxicity on both cancerous HeLa and noncancerous Chinese hamster ovary cells. The labeling of cancerous HeLa cells is also demonstrated. 相似文献
76.
The effect of 280 nm irradiation on a family of synthetic DNA hairpins possessing an alkane linker connecting a six-base pair stem having a single T-T step located at different positions within the hairpin has been investigated. A single adduct assigned to the product of 2+2 dimerization is obtained except in the case of a T-T step located adjacent to the linker, in which case both 2+2 and 6-4 adducts are obtained. The efficiency of dimerization is similar for three hairpins having a T-T step located within the duplex interior. Lower efficiency is observed for a T-T step located at the open end of the hairpin and in T overhangs, whereas higher efficiency is observed for the T-T step adjacent to the linker and in a single T bulge. The context-dependence of dimerization efficiency is discussed. 相似文献
77.
Using the British Admiralty bathymetric charts off the West Coast of India and employing the graphical method of constructing wave refraction diagrams, an attempt is made to study the behaviour of the shortperiod waves (4, 5 and 6 seconds) which are found to affect the coast generally in the neighbourhood of Cochin Port entrance. Nineteen stations, at intervals of roughly one mile, are chosen around the three-fathom line in this area. Considering a probable field of approach of deep-water waves, limited to a cone of 90°, five directions of approach are chosen at intervals of 22 1/2;° in the range of 202 1/2° to 292 1/2°. Refraction diagrams are prepared for these directions and periods, and from these, the refraction functions and directional parameters are evaluated for each station. The possible directions of flow of long-shore current and the areas vulnerable to erosion and sedimentation are investigated. 相似文献
78.
Frequency doubling of femtosecond erbium-fiber soliton lasers in periodically poled lithium niobate 总被引:2,自引:0,他引:2
We report efficient frequency doubling of passively mode-locked femtosecond erbium-fiber lasers. Quasi-phase-matched second-harmonic generation in periodically poled lithium niobate is used to generate 8.1 mW of 190-fs (FWHM), 90-pJ pulses at 777 nm with a conversion efficiency greater than can be obtained with existing birefringently phase-matched nonlinear materials. A dispersion-compensation-free soliton oscillator generating transform-limited 230-fs (FWHM) pulses at 1554 nm is used as a pump laser. 相似文献
79.
Abstract Aromatic polyesters were obtained in relatively good yields (~ 70%) from reactions of 3- and 4-bromomethylbenzoic acids with tri-ethylamine in chlorobenzene. A copolymer was prepared in 58% yield by reaction of a 1:1 mixture of the two acids under similar conditions. The polyesters were characterized by IR, 1H- and 133C-NMR spectra, x-ray powder diffraction, DSC behavior, solution viscosity, and hydrolysis to the corresponding hydroxymethylbenzoic acids. Molecular weights were determined by 1H-NMR endgroup analysis. Possible mechanisms for the reactions are discussed. 相似文献
80.
In 1959, Horiguchi and Kandatsu1 first isolated 2-aminomethylphos-phonic acid from ciliate protozoa. Since then the compound has been found in numerous other organisms2 and recently it has been found in human brain3, liver, heart and skeletal muscles4, and in red blood cell membrane. These findings establish the biological importance of the carbon-phosphorus bond in nature. Quin2 suggested that the naturally occurring aminophosphonic acids are bound to proteins and peptides. 相似文献