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71.
Nitrogen doped TiO2 (TiO2−xNx) with a homogenous anatase phase was synthesized, using β-alanine as a nitrogen precursor and ethanol as a oxygen depriving
agent in the concentration range of 0.05, 0.10, 0.15 and 0.2 at% and were characterized by Powder X-ray Diffraction (PXRD),
X-ray Photoelectron Spectra (XPS), Scanning Electron Microscope (SEM), Fourier Transform Infrared (FT-IR) and UV–visible Diffused
Reflectance Spectroscopic (DRS) techniques. Ethanol deprives the surface oxygen, thereby generating oxygen defects whose concentration
was evaluated by FTIR, Photoluminescence (PL) and Electron Spin Resonance (ESR) studies. FTIR analysis reveal that concentration
of oxygen vacancies/defects (Vo) decreases as the nitrogen concentration increases leading to the reduction in the Ti–O bond length. This results in a shift
of the IR absorption peak towards a low wave number as predicted by simple physical harmonic oscillator model. The Ti 2p3/2 XPS spectra of TiO2−xNx shifts to lower binding energies due to the increase in the electron densities around the Ti atoms indicating the formation
of Ti3+ in the doped samples. N2 adsorption–desorption isotherms measurements show a slight increase in the Brunner–Emmet–Teller (BET) surface area, pore
diameter, mesopore volume, while the crystallite size and the morphology were also effected by the nitrogen doping. The equilibrium
adsorption of Toluene molecules on the photocatalyst surface follows Langmuir theory and the rate controlling step could be
the surface reaction of the adsorbed Toluene molecules. 相似文献
72.
Petros Drineas Michael W. Mahoney S. Muthukrishnan Tamás Sarlós 《Numerische Mathematik》2011,117(2):219-249
Least squares approximation is a technique to find an approximate solution to a system of linear equations that has no exact
solution. In a typical setting, one lets n be the number of constraints and d be the number of variables, with n >> d{n \gg d}. Then, existing exact methods find a solution vector in O(nd
2) time. We present two randomized algorithms that provide accurate relative-error approximations to the optimal value and
the solution vector of a least squares approximation problem more rapidly than existing exact algorithms. Both of our algorithms
preprocess the data with the Randomized Hadamard transform. One then uniformly randomly samples constraints and solves the
smaller problem on those constraints, and the other performs a sparse random projection and solves the smaller problem on
those projected coordinates. In both cases, solving the smaller problem provides relative-error approximations, and, if n is sufficiently larger than d, the approximate solution can be computed in O(nd ln d) time. 相似文献
73.
There are many data clustering techniques available to extract meaningful information from real world data, but the obtained clustering results of the available techniques, running time for the performance of clustering techniques in clustering real world data are highly important. This work is strongly felt that fuzzy clustering technique is suitable one to find meaningful information and appropriate groups into real world datasets. In fuzzy clustering the objective function controls the groups or clusters and computation parts of clustering. Hence researchers in fuzzy clustering algorithm aim is to minimize the objective function that usually has number of computation parts, like calculation of cluster prototypes, degree of membership for objects, computation part for updating and stopping algorithms. This paper introduces some new effective fuzzy objective functions with effective fuzzy parameters that can help to minimize the running time and to obtain strong meaningful information or clusters into the real world datasets. Further this paper tries to introduce new way for predicting membership, centres by minimizing the proposed new fuzzy objective functions. And experimental results of proposed algorithms are given to illustrate the effectiveness of proposed methods. 相似文献
74.
Gowri S Uma Devi T Sajan D Bheeter SR Lawrence N 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,81(1):257-260
A new organic nonlinear optical material L-tryptophanium picrate was synthesized. From the powder XRD pattern the various planes of reflections were identified. The grown crystals were subjected to FT-IR and (1)H NMR spectral analyses to confirm the synthesized compound. Thermal properties of the crystals were investigated using thermo gravimetric (TG) and differential thermal analyses (DTA). The second harmonic generation (SHG) efficiency of the title compound was found using the modified experimental setup of Kurtz and Perry. 相似文献
75.
Johra Khan Prashanta Kumar Deb Somi Priya Karla Damin Medina Rajlakshmi Devi Sanjay G. Walode Mithun Rudrapal 《Molecules (Basel, Switzerland)》2021,26(13)
Flavonoids comprise a large group of structurally diverse polyphenolic compounds of plant origin and are abundantly found in human diet such as fruits, vegetables, grains, tea, dairy products, red wine, etc. Major classes of flavonoids include flavonols, flavones, flavanones, flavanols, anthocyanidins, isoflavones, and chalcones. Owing to their potential health benefits and medicinal significance, flavonoids are now considered as an indispensable component in a variety of medicinal, pharmaceutical, nutraceutical, and cosmetic preparations. Moreover, flavonoids play a significant role in preventing cardiovascular diseases (CVDs), which could be mainly due to their antioxidant, antiatherogenic, and antithrombotic effects. Epidemiological and in vitro/in vivo evidence of antioxidant effects supports the cardioprotective function of dietary flavonoids. Further, the inhibition of LDL oxidation and platelet aggregation following regular consumption of food containing flavonoids and moderate consumption of red wine might protect against atherosclerosis and thrombosis. One study suggests that daily intake of 100 mg of flavonoids through the diet may reduce the risk of developing morbidity and mortality due to coronary heart disease (CHD) by approximately 10%. This review summarizes dietary flavonoids with their sources and potential health implications in CVDs including various redox-active cardioprotective (molecular) mechanisms with antioxidant effects. Pharmacokinetic (oral bioavailability, drug metabolism), toxicological, and therapeutic aspects of dietary flavonoids are also addressed herein with future directions for the discovery and development of useful drug candidates/therapeutic molecules. 相似文献
76.
J.P. Bouanich A. Predoi-Cross R.L. Sams C.P. Rinsland V. Malathy Devi 《Journal of Molecular Spectroscopy》2005,231(1):85-95
A semiclassical theory based upon the Robert-Bonamy formalism has been developed to explain the experimental measurements of self-broadening, self-induced pressure shift coefficients in the ν1,ν2, 2ν2 bands of H12C14N and the 2ν1 band of H13C14N, as well as the temperature dependences of these parameters with special emphasis on the ν2 band. Our calculations include only electrostatic interactions and neglect the vibrational dependence of the isotropic part of the intermolecular potential, which probably has a weak contribution to the HCN self-shifts for the bands investigated in this study. The agreement between theory and measurements is good in the cases of self-broadening coefficients and their variation with temperature, as well as the self-shift coefficients determined at room temperature. However, the observed temperature dependence of self-shift coefficients in the ν2 band is different from that derived theoretically. 相似文献
77.
Silica gels doped with vanadium were prepared from tetra ethyl orthosilicate and an aqueous solution of NH4VO3, at a final sol pH of 1.5–2.5. Absorption and electron paramagnetic resonance (EPR) spectral studies establish that under ambient conditions the incorporated pentavalent vanadium is stabilized as tetravalent vanadyl ion in the gel monoliths. Dried gels were very stable under ambient conditions, however, transformation of V4+ to V5+ was noted during gel densification. 相似文献
78.
Dipak Prajapati Dhrubojyoti D. LaskarBaikuntha J. Gogoi Gitali Devi 《Tetrahedron letters》2003,44(35):6755-6757
The indium-catalysed coupling of propargyl bromide with a variety of imines and imine oxides afforded the corresponding propargylated products in high yields under mild conditions. 相似文献
79.
80.
Miss R. Girija Devi 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1973,24(3):375-385
Summary The flow of a micropolar fluid for sinusoidally deforming boundaries is discussed in detail. The velocity and microrotation fields and the streamfunction are determined and plotted under the assumption of small deformations.
Zusammenfassung Die Strömung einer mikropolaren Flïssigkeit mit sinusoidaler Verformung der Begrenzung wird ausführlich diskutiert. Die Geschwindigkeits- und Mikrorotationsfelder und die Stromfunktion werden mit der Annahme einer kleinen Verformung bestimmt und graphisch dargestellt.相似文献