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21.
We present a 3-dimensional, linear analysis of electrohydrodynamic (EHD) roll instability in a nematic liquid crystal under
DC excitation. It is shown that the flexoelectric effect leads to a new symmetry of the flow pattern, viz. ahelical flow inoblique rolls. Our experimental observations agree with the theoretical predictions. 相似文献
22.
23.
Harroun TA Koslowsky M Nieh MP de Lannoy CF Raghunathan VA Katsaras J 《Langmuir : the ACS journal of surfaces and colloids》2005,21(12):5356-5361
Mixtures of long- and short-chain phospholipids, specifically 14:0 and 6:0 phosphatidylcholines (DMPC and DHPC), have been used successfully in NMR studies as magnetically alignable substrates for membrane-associated proteins. However, recent publications have shown that the phase behavior of these mixtures is much more complex than originally thought. Using polarized light microscopy and small-angle neutron scattering, phase diagrams of DMPC/DHPC mixtures at molar ratios of 2, 3.2, and 5 have been determined. Generally, at temperatures below the main-chain melting transition of DMPC (T(M) = 23 degrees C), an isotropic phase of disk-like micelles is found. At high temperatures (T > 50 degrees C), a lamellar phase consisting of either multilamellar vesicles (MLV) or extended lamellae is formed, which at low lipid concentrations (e.g., MLV) coexists with an excess of water. At intermediate temperatures and lipid concentrations, a chiral nematic phase made up of worm-like micelles was observed. 相似文献
24.
R. Divakar D. Sundararaman V.S. Raghunathan 《Progress in Crystal Growth and Characterization of Materials》1997,34(1-4):263-269
AlCuFe quasicrystal has been considered a novel icosahedral quasicrystal in as much as it can be produced in both thermodynamically stable and metastable state. It is also recognised to be a face centred structure. The system has been studied extensively in the recent past and several contentious results have been obtained. For example, evidences have been presented for both reversible and irreversible transformation of the quasicrystalline phase to the crystalline phases. Similarly, distinct transition metal sites have been proposed based on the Mossbauer studies. A subsequent study of this in fact shows an absence of such distinct sites. It has been shown that in this system, vacancy type of defects of very large concentrations exist. Many of these factors bring into question, the various structural models that have been postulated to explain the icosahedral structure obtained in the system. A critical examination of these various aspects of the AlCuFe quasicrystal is presented. 相似文献
25.
R. Krishna D. Velmurugan M. Shanmugasundaram R. Raghunathan K. Sekar S. Shanmuga Sundara Raj H.‐K. Fun 《Crystal Research and Technology》2002,37(1):135-141
The crystal structure of the title compound “1′,2′,3′,4′‐tetrahydro‐1,3‐diphenyl‐4‐chlorospiro[2‐pyrazoline‐5,2‐napthalen] 1′one” has been determined. The structure consists of a pyrazoline ring, three aromatic rings and a tetralone moiety. All the aromatic rings are planar while the cyclohexonone ring of the tetralone moiety is in the distorted sofa conformation. The molecular packing is stabilized by C‐H…O and C‐H…π type inter molecular interactions. 相似文献
26.
Muthian Shanmugasundaram Srinivasarao Arulananda Babu Raghavachary Raghunathan Ezekiel J. Padma Malar 《Heteroatom Chemistry》1999,10(4):331-336
Synthesis of a series of novel 1,3‐diphe nyl‐4‐arylspiropyrazolines[5.21]‐11‐tetralones has been accomplished in good yield by regioselective 1,3‐dipolar cycloaddition of diphenylnitrilimine with (E)‐2‐arylidene‐1‐tetralones. X‐ray crystal structure analysis of one of the products 4b confirms the structure and the regiochemistry of cycloaddition. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 331–336, 1999 相似文献
27.
Synthesis of novel pyranopyrrole derivatives has been achieved by a one-pot IMHDA reaction of N-substituted aldehydes with various diones in the presence of ethylene diaminediacetate (EDDA) in excellent yields under mild conditions. 相似文献
28.
A. R. Suresh Babu R. Raghunathan G. Gayatri G. Narahari Sastry 《Journal of heterocyclic chemistry》2006,43(6):1467-1472
29.
J. Naga Siva RaoR. Raghunathan 《Tetrahedron letters》2012,53(7):854-858
Synthesis of pyrrolidinyl-spirooxindoles fused to sugar lactone has been achieved by a one pot three component 1,3-dipolar cycloaddition (1,3-DC) reaction. A unique dipolarophile (α,β-unsaturated lactone) derived from d-glucose/d-galactose reacted with azomethine ylide generated in situ from isatin/N-substituted isatin and secondary amino acids (sarcosine/proline/piperidine-2-carboxylic acid) to give the corresponding cycloadducts in good yield. The cycloaddition was found to be highly regio- and diastereoselective. 相似文献
30.
Alexander Lubotzky Shahar Mozes M. S. Raghunathan 《Publications Mathématiques de L'IHéS》2000,91(1):5-53
Let G be a semisimple Lie group of rank ⩾2 and Γ an irreducible lattice. Γ has two natural metrics: a metric inherited from
a Riemannian metric on the ambient Lie group and a word metric defined with respect to some finite set of generators. Confirming
a conjecture of D. Kazhdan (cf. Gromov [Gr2]) we show that these metrics are Lipschitz equivalent. It is shown that a cyclic
subgroup of Γ is virtually unipotent if and only if it has exponential growth with respect to the generators of Γ. 相似文献