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排序方式: 共有350条查询结果,搜索用时 46 毫秒
1.
Seema Prasad 《Molecular Crystals and Liquid Crystals》2018,665(1):52-63
Molecular structure and vibrational spectroscopic studies of higher homologous series nematogenic p-n-alkylbenzoic acids (nBAC) that have 6 (6BAC) and 7 (7BAC) carbon atoms in the alkyl chain have been investigated using the Density Functional Becke3-Lee-Yang-Parr (B3LYP) level with the basis set 6-31++G (d.p) and Hartree Fock (HF) with the same basis set. The observed vibrational spectra has been resolved and assigned in detail for comparision with both the molecules. These results indicate that DFT and HF values are slightly different at both the levels. A comparision of chemical reactivity such as HOMO (EH), LUMO (EL) energies, energy gap (Eg), ionization energy (I), electron affinity (A), electro negativity (χ), chemical hardness (η), electronic chemical potential (μ), electrophilicity index (ω), and softness (S) has been made. It has been observed that the decrement has occurred in the energy band gap value of isolated molecule with increment in alkyl chain length. This provides valuable information regarding enhancing the stability of liquid crystal materials by maintaining the conductivity. 相似文献
2.
Heavy ion irradiation in the electronic stopping power region induces macroscopic dimensional change in metallic glasses and introduces magnetic anisotropy in some magnetic materials. The present work is on the irradiation study of ferromagnetic metallic glasses, where both dimensional change and modification of magnetic anisotropy are expected. Magnetic anisotropy was measured using Mössbauer spectroscopy of virgin and irradiated Fe40Ni40B20 and Fe40Ni38Mo4B18 metallic glass ribbons. 90 MeV 127I beam was used for the irradiations. Irradiation doses were 5×1013 and 7.5×1013 ions/cm2. The relative intensity ratios D 23 of the second and third lines of the Mössbauer spectra were measured to determine the magnetic anisotropy. The virgin samples of both the materials display in-plane magnetic anisotropy, i.e., the spins are oriented parallel to the ribbon plane. Irradiation is found to cause reduction in magnetic anisotropy. Near-complete randomization of magnetic moments is observed at high irradiation doses. Correlation is found between the residual stresses introduced by ion irradiation and the change in magnetic anisotropy. 相似文献
3.
Doshi DA Shah PB Singh S Branson ED Malanoski AP Watkins EB Majewski J van Swol F Brinker CJ 《Langmuir : the ACS journal of surfaces and colloids》2005,21(17):7805-7811
Neutron reflectivity (NR) is used to probe the solid, liquid, vapor interface of a porous superhydrophobic (SH) surface submerged in water. A low-temperature, low-pressure technique was used to prepare a rough, highly porous organosilica aerogel-like film. UV/ozone treatments were used to control the surface coverage of hydrophobic organic ligands on the silica framework, allowing the contact angle with water to be continuously varied over the range of 160 degrees (superhydrophobic) to <10 degrees (hydrophilic). NR shows that the superhydrophobic nature of the surface prevents infiltration of water into the porous film. Atomic force microscopy and density functional theory simulations are used in combination to interpret the NR results and help establish the location, width, and nature of the SH film-water interface. 相似文献
4.
A new tetradentate dihydrogen perchlorate macrocyclic ligand (2,4,9,11-tetraphenyl-1,5,8,12-tetraazacyclotetradeca-1,4,8,11-tetraene dihydrogen perchlorate) was prepared and characterised. The macrocycle behaves as a selective chelating ion-exchanger for some metal ions. The polystyrene-based membrane electrode is found to exhibit quite promising selectivity for Cr3+ ions. It can be used to estimate chromium concentrations in the range 3.16x 10(-6)-1.00x10(-1) M with a near-Nernstian slope of 17.5 mV per decade of concentration between pH 3.0 to 6.5. The electrode is found to possess a fast response time of 15 s and was used over a period of three months with good reproducibility (s = +/- 0.3 mV). The selectivity coefficient values for mono-, di- and trivalent cations indicate excellent selectivity for Cr3+ ions over a large number of other cations. Anions such as Cl- and SO4(2-) do not interfere and the electrode also works satisfactorily in a mixed organic-water solution. The sensor has been used as an indicator electrode for the potentiometric titration of Cr3+ with EDTA. The practical utility of the membrane sensor has also been demonstrated in solutions contaminated with detergents (CTAB and SDS). Above all, the membrane sensor has been very successfully used to determine Cr3+ in some foods. 相似文献
5.
C. D. Kalkar S. V. Doshi Seema Teli 《Journal of Radioanalytical and Nuclear Chemistry》1989,136(4):283-290
The oxidation of iron/II/ ions has been studied by dissolving -irradiated NaCl crystals in aqueous Fricke solution. The yield of iron/III/ ions was determined as a function of the amount of NaCl added, storage time, dose, concentration of iron/II/ ions and pH of the Fricke solution. The energy transfer parameter, , which is the ratio of G/Fe3+/ obtained by the addition of irradiated NaCl to that by direct radiolysis was evaluated. 相似文献
6.
7.
Kanchan Kothari Ramji Lal M. R. A. Pillai 《Journal of Radioanalytical and Nuclear Chemistry》1995,196(2):331-338
A direct radioimmunoassay for the measurement of progesterone in human serum is described. Progesterone 11-hemisuccinate was conjugated to tyrosine methyl ester (TME) by the mix anhydride method and then iodinated using chloramine-T. The radiochemical purity of different batches of125I-progesterone was greater than 95% and showed 70–75% binding with excess antibody. Progesterone 11-hemisuccinate was coupled with BSA and injected to rabits. Antisera collected after three booster injections and having aK value of 1·1091/M was selected for the assay. Significant reduction in binding with antibody was seen when hormone free serum was used in the assay system. Various blocking agents were tried to reduce the serum effects and none of them were found satisfactory. From a series of optimization experiments, an assay was developed without the use of blocking agents. This assay used a much higher concentration of antibody along with lower amount of serum sample (50 l). The optimized assay has a sensitivity of 0.5 nj/ml and a working range of 0.5 to 100 ng/ml. Serum samples were analyzed analysis showed good correlation between the results obtained from the present system and the DPC kit. (Y=0.93X+0.5,r=0.93, forn=25). 相似文献
8.
Microwave-assisted acyl chloride-isonitrile condensation and CaCO3-mediated hydrolysis constitute a one-pot, 2-minute process to prepare α-ketoamides. 相似文献
9.
Nakanishi S Lu G Kothari HM Bohannan EW Switzer JA 《Journal of the American Chemical Society》2003,125(49):14998-14999
Epitaxial Prussian blue (PB) films are deposited electrochemically onto a Au(110) substrate. High-resolution X-ray diffraction shows that the PB films have a [111] out-of-plane orientation. The very large lattice mismatch of 148% is reduced to about 1% by the formation of (1 x 2)PB(111)[onemacr;10]//(6 x 5)Au(110)[onemacr;10] and (1 x 2)PB(111)[01onemacr;]//(6 x 5)Au(110)[onemacr;10] epitaxial relationships. Peaks in the cyclic voltammogram of PB on Au(110) are sharper than those on polycrystalline Au, consistent with higher structural order and a single out-of-plane orientation. The development of epitaxial films of PB and PB analogues will allow the measurement of the orientation-dependent properties of these molecular magnets. It will also open the door to the development of novel molecular spintronic devices, such as those which exhibit spin-dependent electron transfer. 相似文献
10.