排序方式: 共有31条查询结果,搜索用时 31 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.
Probability Theory and Related Fields - 相似文献
6.
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
7.
In this article we study the max domains of attraction of distributions of sums of independent random variables belonging
to the max domains of attraction of max stable laws under linear normalization. These results lead to the study of the max
domains of attraction of distributions of products of independent random variables belonging to the max domain of attraction
of max stable laws under power normalization. 相似文献
8.
Sie Tiong Ha Kok Leei Foo Hong Cheu Lin Masato M.Ito Kazuma Abe Kenji Kunbo S.Sreehari Sastry 《中国化学快报》2012,23(7):761-764
正A homologous series of heterocycles,6-methyl-2-(4-alkoxybenzylidenamino)benzothiazoles,were synthesized and characterized using FT-IR,~1H and ~(13)C NMR and mass spectrometric analysis.Enantiotropic nematic phase was observed for shorter members.Smectic A phase only emerged from octyloxy derivative onwards.The terminal methyl group at the benzothiazole fragment and the Schiff base linkage influenced the mesomorphic behavior of the present series. 相似文献
9.
Kok-Leei Foo Yip-Foo Win Guan-Yeow Yeap Hong-Cheu Lin S. Sreehari Sastry 《Liquid crystals》2013,40(11):1516-1525
The synthesis and characterisation of a series of new rod-shaped liquid crystal (LC), 2-(4-alkyloxybenzylidenamino)benzothiazoles possessing even number of carbon atoms at the alkyloxy chain (CnH2n?+?1O-, n = 2, 4, 6, 8, 10, 12, 14, 16, 18) are reported. The molecular structures of title compounds were elucidated using FTIR and nuclear magnetic resonance spectroscopic techniques. The phase behaviour of these new compounds was characterised and studied by differential scanning calorimetry and polarising optical microscopy. Lower members (n = 2, 4 and 6) did not exhibit mesophase. Octyloxy derivative was monotropic LC. Enantiotropic smectic A phase was observed from n-decyloxy derivatives onward to the last homologous synthesised. 相似文献
10.
A series of new calamitic liquid crystals 2-[4-(4-alkyloxybenzoyloxy)-phenyl]benzothiazoles comprising a benzothiazole core, terminal alkyl chain and an ester linkage were synthesised and characterised. This series consists of 13 members, wherein the members differ by the length of alkyloxy chain (C n H2n+1O?, where n?=?2–10, 12, 14, 16, 18). Their mesomorphic properties were studied by using differential scanning calorimetry, optical polarising microscopy and powder X-ray diffraction techniques. Enantiotropic nematic phase was present throughout the series, i.e. from the lowest member (n?=?2) until the highest member (n?=?18) of the series. The smectic A phase emerged from the nonyloxy derivative onwards. 相似文献