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1.
Justina Grabowska Karuna Kar Nanda R.T. Rajendra Kumar J.P. Mosnier M.O. Henry Simon B. Newcomb Patrick McNally Lisa OReilly Xu Lu Enda McGlynn 《Superlattices and Microstructures》2007,42(1-6):327
Self-organized ZnAl2O4 nanostructures with the appearance (in SEM) of high aspect ratio horizontal nanowires are grown on uncatalysed c-sapphire by vapour phase transport. The nanostructures grow as three equivalent crystallographic variants on c-sapphire. Raman and cathodoluminescence spectroscopy confirm that the nanostructures are not ZnO and TEM shows that they are the cubic spinel, zinc aluminate, ZnAl2O4, formed by the reaction of Zn and O with the sapphire substrate. 相似文献
2.
Raj Gandhi Kamales Kar S. Uma Sankar Abhijit Bandyopadhyay Rahul Basu Pijushpani Bhattacharjee Biswajoy Brahmachari Debrupa Chakraborti M. Chaudhury J. Chaudhury Sandhya Choubey E. J. Chun Atri Desmukhya Anindya Datta Gautam Dutta Sukanta Dutta Anjan Giri Sourendu Gupta Srubabati Goswami Namit Mahajan H. S. Mani A. Mukherjee Biswarup Mukhopadhyaya S. N. Nayak M. Randhawa Subhendu Rakshit Asim K. Ray Amitava Raychaudhuri D. P. Roy Probir Roy Suryadeep Roy Shiv Sethi G. Sigl Arunansu Sil N. Nimai Singh Mark Vagins Urjit Yagnik 《Pramana》2003,60(2):405-409
This is the report of neutrino and astroparticle physics working group at WHEPP-7. Discussions and work on CP violation in
long baseline neutrino experiments, ultra high energy neutrinos, supernova neutrinos and water Cerenkov detectors are discussed. 相似文献
3.
The subject of spectral distribution methods where one derives and applies the locally smoothed forms of observables in nuclei
is briefly reviewed. It is well understood that the local forms (with respect to energy) of the level density function, expectation
values and strength densities are Gaussian, linear (or ratio of Gaussians) and a bivariate Gaussian respectively. To accomodate
symmetries in the above forms, one has to deal with multivariate distributions in general; for example the angular-momentum
(J) decomposition leads to a bivariate Gaussian form for the level density. These results extend to indefinitely large spaces
by method of partitioning and they generate convolution forms. The origin of these remarkable spectral properties is discussed
and shell model examples are given to substantiate their applicability to nuclear systems. Spectral distribution theory is
a practical, usable theory because the smoothed forms are defined in terms of traces of low particle-rank operators, and the
trace information propagates. Finally we discuss the application of the spectral methods for a wide range of nuclear problems;
these include binding energies, orbit occupancies, electromagnetic andβ-decay sum rule quantities, analysis of operators, symmetry breaking, numerical level densities, and determination of bounds
on time-reversal non-invariant part of nucleon-nucleon interaction. 相似文献
4.
5-Aminolevulinic acid and its esterified analogues have been under much investigation to enhance the endogenous production of protoporphyrin IX (PpIX) in tumor cells. However, in this work, we studied the in vitro and in vivo efficacy of exogenously administered PpIX and its esterified analogue, PpIX dimethyl ester (PME), in poorly differentiated human nasopharyngeal carcinoma (NPC/CNE-2) as a photodynamic diagnostic (PDD) agent. NPC/CNE-2 at its earliest time, 1 h after incubation with PME in in vitro studies, has exhibited 64% (P <0.01) higher tumor to normal cell (T/N) fluorescence ratio than with PpIX. In an in vivo mouse xenograft model, comparable photosensitizer concentration in tumor after intravenous administration was observed at 1-3 h time points, but at 9 h, PME had 31% (P=0.05) greater concentration in tumor compared with PpIX. In addition, by constituting PME and PpIX in different topical gel composites, of which, PME gel composition of 8:2 Plasdone and Gantrez resulted in the highest T/N ratio at 6 h after application (34%; P <0.05) in comparison with other gel composites. Evaluation of PME and PpIX constituted in the delivery vehicles investigated showed comparable selectivity for tumor at 1-3 h, thus neither photosensitizer is more efficient than the other for PDD at the early time points; however, beyond 6 h, PME had higher selectivity for tumor compared with PpIX. Thus, further investigation is warranted to improve the drug delivery vehicle for greater tumor selectivity at a shorter incubation time. 相似文献
5.
Indrajit Kar B. M. Mandal S. R. Palit 《Journal of polymer science. Part A, Polymer chemistry》1969,7(10):2829-2836
Chain transfer constants of some fluoroalcohols [HCF2(CF2)n?1CH2OH, n = 2, 4, 6] in the catalyzed polymerization of vinyl acetate, styrene, acrylonitrile, and methyl methacrylate at 60°C have been evaluated by a method based on degree of polymerization. Since fluoroalcohols are normally nonsolvents for polymers, a homogeneous reaction phase is maintained by carrying out the polymerization in benzene (except in case of acrylonitrile, where no solvent was used). The transfer constants vary, depending on the reactivity as well as the polarity of the radicals, in the following order: vinyl acetate > styrene > methyl methacrylate > acrylonitrile. Of the three fluoroalcohols studied, the transfer constants increase with the increasing value of n. The results have been interpreted in terms of polar structure contribution in the transition state of the transfer reactions. 相似文献
6.
7.
8.
We look at some one-dimensional semi-infinite superlattices with an underlying Hamiltonian that is of the nearest neighbour, tight binding type. A real space rescaling procedure which is exact in one dimension is applied to obtain the location of the subbands. It has been found that these subbands never overlap in 1D, and we interpret this as a band repulsion effect. Relevance in the case of a disordered system where this band repulsion crosses over to the well-known level repulsion is discussed. Then with a proper matching at the boundary we solve for the sets of denumerably infinite number of decaying solutions (the surface states) in the gaps. These types of states have been proposed quite some time ago. We look at detail theirexact analytical solutions in 1D and find that their decay lengths near the band edges diverge as |E–E
b|–v, wherev=1/2 andE
b is the nearest band edge. The decay lengths and their divergence exponent match extremely well with those obtained from transfer matrix method. Some recent experiments on quantum well structures seem to have observed such states. 相似文献
9.
Controlled synthesis and photoluminescence properties of ZnS nanowires and nanoribbons 总被引:2,自引:0,他引:2
Rapid synthesis of wurtzite ZnS nanowires and nanoribbons has been achieved by a simple thermal evaporation of ZnS powder onto Si substrate in the presence of Au catalyst. A vapor-liquid-solid process is proposed for the formation of the ZnS nanostructures. The flow rate of the inert carrier Ar gas along with the temperature play an important role in defining the morphology of the ZnS nanostructures. The morphological change of the ZnS nanostructures and their growth sequence were studied through scanning electron microscopy. Room-temperature photoluminescence measurements showed intense blue emission at approximately 398 nm from both the nanowires and the nanoribbons. 相似文献
10.
Localized molecular orbitals, two- and three-center bond indices of 1,5-dicarba-closo-pentaborane ( 5 ) and 1,5-dicarba-closo-pentaborane ( 3 ) and their hydrocarbon analogs bicyclo [1,1,1]-pentane and [1,1,1] propellane, respectively, have been calculated using a suitable basis set. No previously reported three-center CBC bond has been found. However, a new three-center BCB bond has been observed in 1,5-dicarba-closo-pentaborane ( 5 ). © 1995 John Wiley & Sons, Inc. 相似文献