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91.
Following the recent work of Chandleret al on quasi probability distributions for spin-1/2 particles, we show that polarized light can be interpreted in terms of trivariate
probability distributions in two different ways by choosing the variates to correspond to (i) the co-ordinates on the Poincare
sphere, (ii) the components of the spin operator of the photon. In either case, it is shown that the Margenau-Hill procedure
leads to probability mass functions while the Wigner-Weyl approach leads to probability density functions and the well-known
Stokes parameters are also realised as appropriate averages with respect to these distribution functions. 相似文献
92.
93.
Usha Chandra Prerana Mudgal Manoj Kumar Rajeev Rawat G. Parthasarathy Nita Dilawar A. K. Bandyopadhyay 《Hyperfine Interactions》2005,163(1-4):129-141
We report here the Mössbauer measurements on nanocrystalline perovskite structured manganite La0.8Sr0.2Mn0.8Fe0.19
57Fe0.01O3 as a function of pressure up to 10 GPa at room temperature. The nanocrystalline sample, prepared by sol–gel technique found to have crystallite sizes of ∼138 ± 10 Å. Zero-field electrical resistivity measurements with temperature support the nanocrystalline nature. At ambient pressure, Fe3+ as well as Fe4+ ions are distributed in two different environments – Fe3+ in low symmetric site surrounded by Mn3+ ions only while Fe4+ in high symmetric site with at least one Mn3+ ion. Pressure seems to affect the higher symmetric site. A sudden increase in isomer shift at 0.52 GPa indicates the first order phase transition representing the transformation of Fe4+ to Fe3+. Another transition at 3.7 GPa, represents the presence of Fe3+ in single kind of environment. Pressure dependence of electrical resistivity measurements verifies the transitions attributing the first order transition to the cross over of localized-electron to band magnetism. 相似文献
94.
Usha Kulshreshtha 《International Journal of Theoretical Physics》2002,41(2):273-291
The Hamiltonian and BRST formulations of the Nielsen–Olesen (vortex) model are studied in two space, one time dimensions. 相似文献
95.
Arockiam Anthonysamy Sengottuvelan Balasubramanian Govindasamy Usha Devadasan Velmurugan 《Transition Metal Chemistry》2008,33(6):681-690
The free Schiff bases H2MABCE, H2MABCP, and H2MABCT and their complexes [Ni(MABCE)], [Ni(MABCP)], [Ni(MABCT)], [Cu(MABCE)], [Cu(MABCP)], and [Cu(MABCT)] have been synthesized and characterized by spectroscopic, cyclic voltammetric, and thermal studies. The geometry around nickel is square planar with N2O2 donor atoms. Cyclic voltammetric studies of the Ni(II) complexes show one-electron quasi-reversible waves corresponding to Ni(II)/Ni(I) and Ni(II)/Ni(III) processes. The Cu(II) complexes exhibit an irreversible well defined one electron transfer reduction peak in the range of ?0.34 to ?1.08 V. The electronic spectra of the complexes suggest a four-coordinate geometry. The crystal structure of the ligand H2MABCT and the complex [Ni(MABCP)] have also been reported. The mean Ni–N and Ni–O bond distances are Ni–N = 1.849(4) and Ni–O = 1.837(4) Å. 相似文献
96.
Inês Pimentel Moreira Usha Kiran Sanivada Joo Bessa Fernando Cunha Raul Fangueiro 《Molecules (Basel, Switzerland)》2021,26(12)
Different types of heating systems have been developed lately, representing a growing interest in both the academic and industrial sectors. Based on the Joule effect, fibrous structures can produce heat once an electrical current is passed, whereby different approaches have been followed. For that purpose, materials with electrical and thermal conductivity have been explored, such as carbon-based nanomaterials, metallic nanostructures, intrinsically conducting polymers, fibers or hybrids. We review the usage of these emerging nanomaterials at the nanoscale and processed up to the macroscale to create heaters. In addition to fibrous systems, the creation of composite systems for electrical and thermal conductivity enhancement has also been highly studied. Different techniques can be used to create thin film heaters or heating textiles, as opposed to the conventional textile technologies. The combination of nanoscale and microscale materials gives the best heating performances, and some applications have already been proven, even though some effort is still needed to reach the industry level. 相似文献
97.
Convenient chemical synthesis and incorporation of dithymidine and thymidine-cytidine dimer blocks connected with a five-atom amide linker N3'-CO-CH2-S-CH2 into oligonucleotides (ONs) are reported. The UV-Tm experiments for binding affinities of these mixed backbone ONs with complementary DNA and RNA sequences revealed important results such as significantly higher RNA-binding selectivity as compared with complementary DNA. NMR studies of the dimer blocks suggested a marginal increase in the N-type sugar conformations over that of the native DNA. 相似文献
98.
Anjali D. Ruikar Ravindra B. Jadhav Usha D. Phalgune Supada R. Rojatkar Vedavati G. Puranik Nirmala R. Deshpande 《Helvetica chimica acta》2011,94(1):73-77
Two new eudesmanolides, pallensin ( 1 ) and 4‐epipallensin ( 2 ), along with a known eudesmanolide, santonin, and a known flavone, 4‐epivalgarin, have been isolated from the aerial part of A. pallens. Their structures were established by detailed spectral studies (1D and 2D) and by comparison of their spectroscopic data with those of known compounds. 相似文献
99.
Nagamani C Viswanathan U Versek C Tuominen MT Auerbach SM Thayumanavan S 《Chemical communications (Cambridge, England)》2011,47(23):6638-6640
The dynamic nature of hydrogen bonds in phenolic polymers, where the hydrogen bond donor/acceptor reorientation can occur in a single site, presents lower barriers for proton transport. 相似文献
100.
Devi U Brown JR Almond A Webb SJ 《Langmuir : the ACS journal of surfaces and colloids》2011,27(4):1448-1456
A membrane-spanning bis(meso-3-pyridyl) porphyrin 1 has been synthesized, embedded in EYPC vesicles, and upon Pd(II) addition has been shown to form ionophores that allow the passage of anionic 5/6-carboxyfluorescein through membranes. The geometric matching of bis(meso-3-pyridyl) porphyrin 1 and trans-Pd(II) was designed to give a cyclic porphyrin trimer [PdCl(2)(1)](3). However, solution-phase studies showed that PdCl(2)(PhCN)(2) cross linked 1 into linear oligomers at porphyrin concentrations above 10 mM, although the formation of cyclic species was inferred from studies at concentrations below 2 μM. Fluorescence titrations showed that embedding porphyrin 1 in bilayers greatly reduced its affinity for Pd(II), but the combination of porphyrin 1 and Pd(II) gave an ionophoric species that increased the rate of 5/6-carboxyfluorescein (5/6-CF) transit through the phospholipid bilayer 12-fold. A maximum in the 5/6-CF release rate was observed at a Pd(II) concentration of 4 μM, and the application of a solution-phase binding model to the membrane phase showed that this peak in ionophoric activity corresponded to the greatest extent of porphyrin oligomerization. Further studies suggested these Pd(II)/porphyrin oligomers transported 5/6-CF via a channel mechanism. 相似文献