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21.
The nanoceramics of lanthanum (La3+)-modified lead titanate (PbTiO3) with a general formula Pb1?yLayTi(1?y/4)O3 (y = 0.00, 0.06, 0.08, 0.10, 0.12 Lead Lanthanum Titanate (PLT)) were synthesized by a mechanothermal method. Thermal analysis of the PLT samples exhibits their nature of the reaction and thermal stability. The incorporation of La at the Pb site of lead titanate (PT) not only changes the ratios of its unit cell parameters but also reduces the grain and particle size to nanoscale. The dielectric constant of PLT is dependent on La concentration. The La concentration-dependent phase transition temperature of PbTiO3 is one of the main characteristics of the material. 相似文献
22.
Excited-state intramolecular proton transfer distinguishes microenvironments in single- and double-stranded DNA 总被引:1,自引:0,他引:1
Klymchenko AS Shvadchak VV Yushchenko DA Jain N Mély Y 《The journal of physical chemistry. B》2008,112(38):12050-12055
Herein, the efficient interaction of an environment-sensitive fluorophore that undergoes excited-state intramolecular proton transfer (ESIPT) with DNA has been realized by conjugation of a 3-hydroxychromone (3HC) with polycationic spermine. On binding to a double-stranded DNA (dsDNA), the ratio of the two emission bands of the 3HC conjugates changes up to 16-fold, so that emission of the ESIPT product increases dramatically. This suggests an efficient screening of the 3HC fluorophore from the water molecules in the DNA complex, which is probably realized by its intercalation into dsDNA. In sharp contrast, the 3HC conjugates show only moderate changes in the dual emission on binding to a single-stranded DNA (ssDNA), indicating a much higher fluorophore exposure to water at the binding site. Thus, the 3-hydroxychromone fluorophore being conjugated to spermine discriminates the binding of this polycation to dsDNA from that to ssDNA. Consequently, ESIPT-based dyes are promising for monitoring the interaction of polycationic molecules with DNA and probing the microenvironment of their DNA binding sites. 相似文献
23.
Barybin MV Chisholm MH Patmore NJ Robinson RE Singh N 《Chemical communications (Cambridge, England)》2007,(35):3652-3654
The preparation and molecular structure of a W2(4+)-quadruply bonded complex is reported wherein two mutually trans azulene-2-carboxylato ligands are shown to be strongly coupled by ligand pi-M2delta-ligand pi conjugation. 相似文献
24.
Dutta P Ray N Roy S Dasgupta AK Bouloussa O Sarkar A 《Organic & biomolecular chemistry》2011,9(14):5123-5128
A cross-metathesis reaction between an alkene terminated self-assembled monolayer (SAM) on glass/Si wafer and an alkene tethered Fischer carbene complex yielded a functionalized surface. Rapid aminolysis of the Fischer carbene moieties permit efficient anchoring of amine containing molecules on such a surface. Attachment of 1-pyrenemethylamine was thus monitored by ATR-IR spectroscopy and fluorescence microscopy. Similarly, BSA and lysozyme were individually grafted to such Fischer carbene modified surfaces using their pendant lysine residues. It has been demonstrated that the anchored lysozyme retains its bactericidal property. 相似文献
25.
Measurement of(n,α)and(n,2n)reaction cross sections at a neutron energy of 14.92±0.02 MeV for potassium and copper with uncertainty propagation
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A.Gandhi Aman Sharma Rebecca Pachuau Namrata Singh L.S.Danu S.V.Suryanarayana B.K.Nayak A.Kumar 《中国物理C(英文版)》2022,46(1):014002-014002-8
Experimentally measured neutron activation cross sections are presented for the 65Cu(n,0)62mCu,41 K(n,a)38Cl,and 65Cu(n.2n)64Cu reactions with detailed uncertainty propagation.The neutron cross secions were measured at an incident energy of 14.92±0.02 MeV,and the neutrons were based on the(d,n)a fusion reaction.The 27 Al(n,a)24Na reaction was used as a reference reaction for the normalization of the neutron flux.The pre-calib-rated lead-shielded HPGe detector was used to detect the residues'γ-ray spetra.The data from the measured cross sections are compared to the previously measured cross sections from the EXFOR database,theoretically calculated cross sections using the TALYS and EMPIRE codes,and evaluated nuclear data. 相似文献
26.
Namrata I. Jain S. S. Bhoga G. S. Khadekar 《International Journal of Theoretical Physics》2013,52(12):4416-4426
In this paper, the cosmological model with variable $\varLambda= \alpha \frac{\dot{R}^{2}}{R^{2}} + \beta\frac{1}{R^{2}}$ in Kaluza-Klein metric have been studied. Here α and β are dimensionless parameters. The solutions to Einstein field equations which assume that the Universe is filled with perfect fluid have been obtained by using the Gamma Law Equation p=(γ?1)ρ; in which the parameter γ is constant and power law equation A(t)=R n (t)—where A(t) is scale factor for extra dimension and R(t) is scale factor for space dimensions. The fifth dimension for the radiation dominated phases is more prominent with this model. Other physical parameters i.e. density, pressure, deceleration parameter, Hubble parameter have been determined for this model. It is observed physical parameters depends upon constants α, β and n. Neo-classical tests have also been studied in this paper. 相似文献
27.
Effect of co-doping of lanthanum and aluminum on ionic conductivity of CeO2 for its use as a solid electrolyte in intermediate temperature solid oxide fuel cells has been studied. A few compositions in the system Ce1???x???y Al x LayO2???(x?+?y)/2 (CAL) with x?=?0.05, 0.025, and 0.00 and y?=?0.00, 0.025, and 0.05 such that x?+?y?=?0.05 are prepared by auto-combustion method. X-ray diffraction patterns show that all the synthesized samples are ceria-based solid solutions. Microstructures of thermally etched samples have been studied by scanning electron microscope. To determine the contribution of grains, σ g and grain boundaries, σ gb to the total conductivity, σ t impedance is measured in the frequency range 1–1 MHz at different steady temperatures in the range 250–500 °C. It has been found that conductivity of the co-doped composition is more than singly doped with Al but less than singly doped lanthanum composition. 相似文献
28.
Namrata Singh Govindasamy Mugesh 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(23):7879-7883
In this study, we report a remarkably active CeVO4 nanozyme that functionally mimics cytochrome c oxidase (CcO), the terminal enzyme in the respiratory electron transport chain, by catalyzing a four‐electron reduction of dioxygen to water. The nanozyme catalyzes the reaction by using cytochrome c (Cyt c), the biological electron donor for CcO, at physiologically relevant pH. The CcO activity of the CeVO4 nanozymes depends on the relative ratio of surface Ce3+/Ce4+ ions, the presence of V5+ and the surface‐Cyt c interactions. The complete reduction of oxygen to water takes place without release of any partially reduced oxygen species (PROS) such as superoxide, peroxide and hydroxyl radicals. 相似文献
29.
The 1,3-dipolar cycloaddition of nitrile oxides, generated from aldoximes and nitroalkanes, to dicyclopentadiene proceeds with complete chemo- and stereoselectivity. The approach of the dipole takes place exclusively from the exo-face of the bicycloheptane moiety providing a mixture of regioisomers in approximately 55:45 ratio. On the other hand, nitrile oxide cycloaddition to dimethyldicyclopentadiene dicarboxylate (Thiele's ester), besides exhibiting chemo- and stereoselectivity as in the case of dicyclopentadiene, exhibits complete regioselectivity as well providing a single isomer in good yield. The Influence of remote substituents, including sterically ‘sterile’ ones, on the regioselectivity has also been investigated using 8-hydroxy and 1-keto derivatives of dicyclopentadiene. These experimental observations have been investigated through gas phase and solvent model MO calculations on the transition state geometries at semiempirical (PM3) and hybrid ab initio-DFT levels of theory. The Computational methods employed in this study were rigorously tested by performing model calculations on well-established experimental observations. 相似文献
30.
Polarization squeezing is shown to occur in non-degenerate parametric amplification of coherent light and the degree of squeezing at interaction time T can be as large as 1 ? e-2T. This gives 86.4% polarization squeezing for T = 1 and 98.2% for T = 2. One simple case when this occurs is on taking initially plane polarized light having equal amplitudes in the two modes that finally has equal intensities of two circular polarizations. This suggest the experimental settings of parameters to achieve this extent of polarization squeezing in coherent light. 相似文献