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101.
Abstract The orientational order and dynamics of perylene in the nematic discotic phase (NdII) of the potassium laurate/KCl/decanol/water system has been investigated by fluorescence depolarization (FD) spectroscopy. The order parameters of perylene-d 12 in the same phase had been previously determined by 2H NMR. FD experiments were performed with the phase-modulation technique in the temperature range between 10°C and 50°C. At each temperature we could determine <P 2> and <P 4> for the axis of the transition moments of perylene, together with the rotational correlation time ΘR. All these quantities assume reasonable values and show regular trends as functions of temperature. In particular, <P 2> is in good agreement with that determined by 2H NMR. 相似文献
102.
In order to obtain chromosome preparations from early-developing embryos of Anilocra physodes, a squash technique has been successfully employed. Results gathered after exposure of this material to bis[dimethyltin(IV)chloro]protoporphyrin IX {[(CH3)2SnCl]2 - Protoporphyrin IX} solutions at different exposure times suggest that this chemical complex is capable of producing abnormal metaphase and anaphase figures in proportion to its concentration and not to exposure length. Essentially, all of the chromosome abnormalities are classifiable as chromosome fragments mainly observed at the metaphase stage; chromosome bridges; and large decondensed chromosome regions. 相似文献
103.
Donata Catalano Claudia Forte Carlo Alberto Veracini J. W. Emsley G. N. Shilstone 《Liquid crystals》1987,2(3):345-355
The orientational ordering in the three related compounds 4,4-di-n-heptyl-d2-azobenzene-d, (HB-d12), 4,4'-di-n-heptyl-d2-azoxybenzene-d, (HAB-d12) and 4,4-di-n-octyl-d2-azoxybenzene-d8 (OAB-d12) has been monitored using deuteron N.M.R. spectroscopy. In these non-rigid molecules it is possible to obtain only the elements of local order matrices. For the aromatic rings these are found to be axially symmetric within the precision of our measurements. The temperature dependences of the local order parameters for the aromatic rings are compared with those predicted by McMillan's theory of smectic A phases. 相似文献
104.
Experimental evidence of light emission due to an anti-stokes photon replica in the extrinsic photoluminescence spectrum of GaS is reported.This non-linear effect has been observed utilizing a high power pulsed ruby laser both for two photon excitation and to provide the electric field for controlling the elementary luminescence event. The experimental result is interpreted on the basis of existing theoretical predictions. 相似文献
105.
The stimulated emission from ZnSe under one photon or two photon excitation has been investigated in the temperature range between 20 and 100 K. The spectra obtained under quasi-resonant one photon pumping show a dominant P line, ascribed to exciton-exciton scattering on the basis of its intensity dependence and its optical gain spectrum. The role of many-body processes under non-resonant one photon excitation is discussed. Under two photon pumping the LO-phonon assisted free exciton recombination is shown to be the dominant lasing mechanism. 相似文献
106.
A. P. Caricato M. R. Belviso M. Catalano M. Cesaria P. D. Cozzoli A. Luches M. G. Manera M. Martino R. Rella A. Taurino 《Applied Physics A: Materials Science & Processing》2011,102(3):605-610
The effects of annealing at 300 °C on gold nanostructures sputtered onto glass substrate were studied using XRD, SAXSees,
the Van der Pauw method and ellipsometry. As-sputtered and annealed samples exhibit a different dependence of the gold lattice
parameter on the sputtering time. With increasing sputtering time the average thickness of the layer and the size of gold
crystallites increased. Another rapid enlargement of the crystallites is observed after annealing. The volume resistivity
decreases rapidly with the increasing sputtering time for both, as-deposited and annealed structures. With increasing sputtering
time initially discontinuous gold coverage changes gradually in a continuous one. Electrically continuous gold coverage on
the as-sputtered and annealed samples exhibits the same concentration of free charge carriers and Hall mobility. Optical constants
of as-deposited and annealed gold films determined by ellipsometry support resistivity measurements and clearly manifest the
presence of plasmons in discontinuous films. 相似文献
107.
Alessia Catalano Alessia Carocci Giovanni Lentini Antonia Di Mola Claudio Bruno Carlo Franchini 《Journal of heterocyclic chemistry》2011,48(2):261-266
Facile, alternative synthetic routes to 6 , (R)‐6 , and (S)‐6 ‐3‐benzyl‐N‐(2,6‐dimethylphenyl)‐1,3‐oxazolidine‐4‐carboxamides ( 6 ), a chiral oxazolidine derivative of tocainide, are reported. The synthetic routes described herein also afforded 11 ‐, (R)‐11 ‐, and 12 , which present the imidazolidin‐4‐one core and belong to a class of compounds interesting for their biological activities. All the final compounds and intermediates were fully characterized. Enantiomeric excesses of homochiral 6 and 11 were determined by capillary electrophoresis analysis using 2‐hydroxypropyl‐β‐cyclodextrin or highly sulfated γ‐cyclodextrin as chiral selectors. J. Heterocyclic Chem., (2010) 相似文献
108.
The trigonally coordinated [AuCu(PPh(2)py)(3)](BF(4))(2) (1) crystallizes in two polymorphs and a pseudopolymorph, each of which contains a trigonally coordinated cation with short Au(I)-Cu(I) separations of ~2.7 ?. Under UV illumination, these crystals luminesce different colors ranging from blue to yellow. The structures of these cations are nearly superimposable, and the primary difference resides in the relative placement of the anions and solvate molecules. As confirmed by time-dependent density functional theory calculations, it is these interactions that are responsible for the differential emission properties. 相似文献
109.
Diego Catalano Ferraioli Paola Morando 《Journal of Nonlinear Mathematical Physics》2014,21(4):521-532
Solvable structures are particularly useful in the integration by quadratures of ordinary differential equations. Nevertheless, for a given equation, it is not always possible to compute a solvable structure. In practice, the simplest solvable structures are those adapted to an already known system of symmetries. In this paper we propose a method of integration which uses solvable structures suitably adapted to both symmetries and first integrals. In the variational case, due to Noether theorem, this method is particularly effective as illustrated by some examples of integration of the geodesic flows. 相似文献
110.
In order to analyze chromosomes for possible numerical and structural alterations in response to exposure to organotin(IV) compounds, gastropod Truncatella subcylindrica specimens were treated with dibutyltin(IV) and tributyltin(IV) chloride solutions with different exposure times. Experimental evidence suggests that tributyltin(IV) chloride is more toxic to this organism than dibutyltin(IV) dichloride at low concentrations. Furthermore, the toxicity responses to these organotin(IV) derivatives seem to be proportional to both concentration and exposure time. The following structural lesions have been identified by comparative analysis of spermatocyte chromosomes from untreated specimens and specimens treated with organotin(IV) compounds: (1) breakages; (2) bridging; (3) irregular outline; and (4) light areas after staining with acetic orcein. In this respect, dibutyltin(IV) and tributyltin(IV) chlorides seem to have an effect similar to that of colchicine. 相似文献