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排序方式: 共有70条查询结果,搜索用时 643 毫秒
1.
S. Sreehari Sastry Sandeep Kumar T. Vindhya Kumari K. Mallika B. Gowri Sankara Rao Ha Sie Tiong 《Liquid crystals》2013,40(12):1527-1537
A technique which combines image analysis and polarising optical microscope (POM) is a useful tool for the physical investigation of discotic liquid crystals, such as hexabutoxytriphenylene and hexahexyloxytriphenylene. This investigation includes the phase transitions, optical properties and order parameter as a function of temperature. Textures of discotic liquid crystals are captured as a function of temperature using POM. These microscopic textures are analysed using MATLAB software to compute statistical parameters, Legendre moments, optical parameters and order parameters of discotic liquid crystal samples. Compared with other techniques in the literature, the proposed methodology is a reliable and very simple technique for the physical investigation of liquid crystals. 相似文献
2.
S. Sreehari Sastry S.T. Ha B. Gowri Sankara Rao K. Mallika T. Vindhya Kumari 《Liquid crystals》2013,40(11):1414-1419
An image analysis technique in conjunction with polarising optical microscopy (POM) is proposed for assessment of the thermo-optical properties of homogeneously aligned chiral ester liquid crystals of the type ((S)-(-)-2-methylbutyl 4′-(4″-n-alkanoyloxybenzoyloxy) biphenyl-4-carboxylates, where n?=?16 or 18. Chiral ester textures are recorded as a function of temperature using POM provided with a hot-stage and a high-resolution colour camera. Temperature-dependent optical parameters, or thermo-optical properties such as optical transmission, degree of polarisation, absorption coefficient and birefringence are computed for chiral esters by analysing the texture of samples using MATLAB software. This is a simple experimental technique for observing how the optical parameters of liquid crystals change with temperature. 相似文献
3.
Peddavarapu Sreehari Raghuraman Srinivasan 《Journal of Thermal Analysis and Calorimetry》2020,141(6):2527-2540
Journal of Thermal Analysis and Calorimetry - This paper presents a new parameter-free stability term via Galerkin mesh-free scheme to solve the multiscale behavior of steady-state... 相似文献
4.
The molecular interactions between the polar systems isopropyl alcohol (IPA) and aniline for various mole fractions at different
temperatures were studied by determining the dielectric permittivity using an HP-LF impedance analyzer at radio frequencies,
the plunger method in the microwave frequency range and Abbe’s refractometer in optical region. Kirkwood effective correlation
factors, corrective Kirkwood correlation factors, excess permittivities, Bruggeman parameters, excess Helmholtz free energy,
relaxation time, dipole moment and excessive dipole moment were calculated using the experimental data. Optimized geometries
were calculated using Spartan Modeling software for both pure and equimolar systems of isopropyl alcohol and aniline for Hamiltonian
quantum mechanical calculations. Conformational analysis of the formation of hydrogen bond between the two systems is supported
by the FT-IR spectra. 相似文献
5.
Seafood, including fish, shrimp, clam, crab, mussel, oyster, lobster, squid, octopus, and cuttlefish samples, was used to compare the recovery of Salmonella serovars by different selective enrichment and isolation media. The samples were selectively enriched in Rappaport-Vassiliadis (RV) broth and tetrathionate broth (TT), followed by selective isolation on Hektoen enteric (HE) agar, xylose lysine desoxycholate (XLD) agar, bismuth sulfite (BS) agar, and Brilliant Green (BG) agar media. Of 443 seafood samples analyzed, 108 were found to be contaminated with Salmonella. The role of selective enrichment in Salmonella spp. recovery with RV medium was distinctly high (70%) compared to TT broth (30%). The selective enrichment in RV broth followed by selective isolation on XLD, HE, BS, and BG agar recovered Salmonella at levels of 56, 41, 28, and 16%, respectively. Similarly, after enrichment in TT broth, XLD and HE agars recovered 27 and 23% respectively. The recovery of Salmonella with enrichment in TT followed by isolation on BS and BG was abysmally low at 4.6 and 5%, respectively. There was no significant difference (P > 0.05) in the recovery of Salmonella using the combinations of XLD and HE media with selective enrichment in RV broth. However, performance difference (P < 0.05) was observed in the recovery when BS and BG with RV, and XLD, HE, BS, and BG agars with TT broth were used. The present study showed that the combination of RV with XLD was the most efficient media for isolation of Salmonella from seafood when compared to other isolation media combinations. 相似文献
6.
K.P. Surendran P.V. Bijumon P. Mohanan M.T. Sebastian 《Applied Physics A: Materials Science & Processing》2005,81(4):823-826
The MgAl2O4 ceramics were prepared by the conventional solid-state ceramic route and the dielectric properties studied in the microwave frequency region (3–13 GHz). The phase purity and crystal structure were identified using the X-ray diffraction technique. The MgAl2O4 spinel ceramics show interesting microwave dielectric properties (εr=8.75, Quxf=68900 GHz (loss tangent = 0.00017 at 12.3 GHz), τf=-75 ppm/°C). The MgAl2O4 has high negative τf, which precludes its immediate use in practical applications. Hence the microwave dielectric properties of MgAl2O4 spinels were tailored by adding different mole fractions of TiO2. The εr and Q factor of the mixed phases were increased with the molar addition of TiO2 into the spinel to form mixtures based on (1-x)MgAl2O4-xTiO2 (x=0.0-1.0). For x=0.25 in (1-x)MgAl2O4-xTiO2, the microwave quality factor reaches a maximum value of Quxf=105400 GHz (loss tangent = 0.00007 at 7.5 GHz) where εr and τf are 11.035 and -12 ppm/°C, respectively. The microwave dielectric properties of the newly developed 0.75MgAl2O4-0.25TiO2 dielectric is superior to several commercially available low loss dielectric substrates. PACS 77.22.-d; 84.40.-x; 81.05.Je 相似文献
7.
Surendran Ramasamy Abdul Rahman Mohamed Subhash Bhatia 《Reaction Kinetics and Catalysis Letters》2002,75(2):353-358
Oxidative coupling of methane for the production of ethylene was studied over Li-Ni/MgO catalyst in a fixed bed reactor. The influences of important reaction parameters such as temperature (T), methane/oxygen ratio (CH4/O2) in feed and space velocity of reactants (V/mcat) were studied over the conversion of methane, yields of ethylene and ethane and selectivity of ethylene formation. The reaction conditions were varied as 650 < T < 850oC, 0.83 x 10-6 < V/mcat < 2.92 x 10-6 m3/g s and 1 < CH4/O2 ratio < 8. 相似文献
8.
Probability Theory and Related Fields - 相似文献
9.
We study the almost sure limiting behavior and convergence in probability of weighted partial sums of the form
where {Wnj, 1jn, n1} and {Xnj, 1jn, n1} are triangular arrays of random variables. The results obtain irrespective of the joint distributions of the random variables within each array. Applications concerning the Efron bootstrap and queueing theory are discussed. 相似文献
10.
Dr. Nguyen Van Nghia Dr. Saibal Jana Surendran Sujith Ji Yeon Ryu Prof. Junseong Lee Prof. Sang Uck Lee Prof. Min Hyung Lee 《Angewandte Chemie (International ed. in English)》2018,57(38):12483-12488
An approach to the design of nido‐carborane‐based luminescent compounds that can exhibit thermally activated delayed fluorescence (TADF) is proposed. 7,8‐Dicarba‐nido‐undecaboranes (nido‐carboranes) having various 8‐R groups (R=H, Me, i‐Pr, Ph) are appended to the meta or para position of the phenyl ring of the dimesitylphenylborane (PhBMes2) acceptor, forming donor–acceptor compounds (nido‐ m1 – m4 and nido‐ p1 – p4 ). The bulky 8‐R group and meta substitution of the nido‐carborane are essential to attain a highly twisted arrangement between the donor and acceptor moieties, leading to a very small energy splitting between the singlet and triplet excited states (ΔEST <0.05 eV for nido‐ m2 , ‐ m3 , and ‐ p3 ). These compounds exhibit efficient TADF with microsecond‐range lifetimes. In particular, nido‐ m2 and ‐ m3 display aggregation‐induced emission (AIE) with TADF properties. 相似文献