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151.
Alex Cao Abhilash K. Pandya Gulay K. Serhatkulu Rachel E. Weber Houbei Dai Jagdish S. Thakur Vaman M. Naik Ratna Naik Gregory W. Auner Raja Rabah D. Carl Freeman 《Journal of Raman spectroscopy : JRS》2007,38(9):1199-1205
This paper introduces a new robust method for the removal of background tissue fluorescence from Raman spectra. Raman spectra consist of noise, fluorescence and Raman scattering. In order to extract the Raman scattering, both noise and background fluorescence must be removed, ideally without human intervention and preserving the original data. We describe the rationale behind our robust background subtraction method, determine the parameters of the method and validate it using a Raman phantom against other methods currently used. We also statistically compare the methods using the residual mean square (RMS) with a fluorescence‐to‐signal (F/S) ratio ranging from 0.1 to 1000. The method, ‘adaptive minmax’, chooses the subtraction method based on the F/S ratio. It uses multiple fits of different orders to maximize each polynomial fit. The results show that the adaptive minmax method was significantly better than any single polynomial fit across all F/S ratios. This method can be implemented as part of a modular automated real‐time diagnostic in vivo Raman system. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
152.
C. Sudakar P. Kharel R. Suryanarayanan J.S. Thakur V.M. Naik R. Naik G. Lawes 《Journal of magnetism and magnetic materials》2008
Thin films of pure TiO2 have been prepared using both spin-coating and sputter-deposition techniques on sapphire and quartz substrates. The structural characteristics of the films have been investigated in detail using Raman spectroscopy and high-resolution transmission electron microscopy (HRTEM). When annealed in vacuum, all films demonstrate room temperature ferromagnetism, while the air-annealed samples show much smaller, often negligible, magnetic moments. The magnetization of the vacuum-annealed sputtered samples depends on film thickness, with the volume magnetization decreasing monotonically with increasing thickness. Furthermore, the magnetization per unit area also decreases slightly with increasing film thickness. These results suggest that ferromagnetism in the vacuum-annealed TiO2 films is mediated by surface defects or interfacial effects, but does not arise from stoichiometric crystalline TiO2. 相似文献
153.
A simple method that uses envelope functions of unbalanced interferometric (auto/cross) correlation signals has been presented
for simultaneous visual detection of pulse chirp and asymmetry, without direction-of-time ambiguity in ultrashort laser pulses.
The ambiguity issues of unbalanced interferometric correlation envelope (ICE) difference signals have been studied. It is
found that unbalanced ICE difference signals are visually different corresponding to practically indistinguishable unbalanced
interferometric autocorrelation (IAC) signals for a distinct symmetric–asymmetric pulse pair with identical intensity autocorrelation
and power spectra. The theoretical analysis of ICE signals is supported by experimental unbalanced IAC signals obtained using
200 fs laser pulses from a cw mode-locked Nd:phosphate laser oscillator.
PACS 42.65.Re; 42.50.Hz; 07.60.Ly 相似文献
154.
Antoine P. Railliet Anil D. Naik Aurelian Rotaru Yann Garcia 《Hyperfine Interactions》2014,226(1-3):223-227
The spin transition properties of [Fe(fletrz)3](BF4)2?2H2O are described. Fletrz (4-(2’-fluoroethyl)-4H-1,2,4-triazole) is a novel fluorine substituted 1,2,4-triazole ligand which forms 1D chain upon self-assembly with FeII ions. This coordination polymer exhibits reversible abrupt thermochromic spin transition that has been probed by SQUID magnetometry, variable temperature 57Fe Mossbauer spectroscopy (77–300 K) and differential scanning calorimetry (100–300 K). 相似文献
155.
A personal computer (PC)-based data acquisition and instrument control system has been developed for neutron spectrometers
in Dhruva reactor hall and Guide Tube laboratory. Efforts have been made to make the system versatile so that it can be used
for controlling various neutron spectrometers using single end-on detector in step scan mode. Commercially available PC add-on
cards have been used for input-output and timer-counter operations. An interface card and DC motor driver card have been developed
indigenously. Software for the system has been written in Visual C++ language using MS Windows operating system. This data
acquisition and instrument control system is successfully controlling four spectrometers at Dhruva reactor. 相似文献
156.
Synthesis and photoluminescence (PL) investigations of lithium metasilicate doped with Eu3+, Tb3+ and Ce3+ were carried out. PL spectra of Eu-doped sample showed peaks corresponding to the 5D0→7Fj (j=1, 2, 3 and 4) transitions under ultraviolet excitation. Strong red emission coming from the hypersensitive 5D0→7F2 transition of Eu3+ ion suggested the presence of the dopant ion in structurally disordered environment. Tb3+-doped silicate sample showed blue-green emission corresponding to the 5D4→7Fj (j=6, 5 and 4) transitions. Ce-doped sample under excitation from UV, showed a broad emission band in the region 350-370 nm with shoulders around 410 nm. The fluorescence lifetimes of Eu3+ and Tb3+ ions were found out to be 790 and 600 μs, respectively. For Ce3+, the lifetime was of the order of 45 ns. PL spectra of the europium- and terbium-doped samples were compared with commercial red (Y2O3:Eu3+) and green (LaPO4:Tb3+) phosphors, respectively. It was found that the emission from the doped silicate sample was 37% of the commercial phosphor in case of the Tb-doped sample and 8% of the commercial phosphor in case of the Eu-doped sample. 相似文献
157.
Reactions of eaq-, H-atom and OH radicals with 3-pyridine methanol (3-PM) and 3-pyridine carboxaldehyde (3-PCA) have been studied at various pHs using pulse radiolysis technique. eaq- was found to be highly reactive with both 3-PM and 3-PCA (k approx. 1010 dm3 mol1 s-1). Semi-reduced species formed in both cases were strongly reducing in nature. In the case of 3-PM, electron addition leads to the formation of pyridinyl radicals whereas in the case of 3-PCA, PyCHOH type radicals are formed. At pH 6.8, H-atom reaction with 3-PCA also gives semi-reduced species (PyCHOH), whereas at pH 1, H-atoms add to the ring. (CH3)2˙COH radicals were found to transfer electron to 3-PCA at all the pH values tested and by making use of changes in the absorption spectra, pKa values of the semi-reduced species were determined to be 4.5 and 10.6. OH radicals were found to undergo addition reaction with 3-PCA, whereas in the case of 3-PM they reacted by H-abstraction as well as addition reaction. By following the yield of methylviologen radical cation formed by electron transfer reaction, it was estimated that approx. 50% of OH radicals react with 3-PM by H-atom abstraction at pH 6.8, giving reducing radicals, whereas at pH 3.2, where 3-PM is in the protonated form, the same is only about 10%. At pH 13, O-˙ radical anions were found to react exclusively by H-atom abstraction. Reaction of SO4-˙ radicals with 3-PCA was found to give a species identical to the one formed by one electron reduction of nicotinic acid at acidic pH values. 相似文献
158.
Mallari A. Naik Satish Patil 《Journal of polymer science. Part A, Polymer chemistry》2013,51(20):4241-4260
The present highlight discusses major work in the synthesis of low bandgap diketopyrrolopyrrole ( DPP )‐based polymers with donor–acceptor–donor ( D–A–D ) approach and their application in organic electronics. It examines the past and recent significant advances which have led to development of low bandgap DPP ‐based materials with phenyl and thiophene as donors. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4241–4260 相似文献
159.
SmFeTeO6 and SmCrTeO6 were synthesized by heating the respective oxides in molar quantities and characterized by X-ray technique. Thermogravimetric studies suggested that SmFeTeO6 and SmCrTeO6 vapourize incongruently according to the reactions: $$ \begin{aligned} {\text{SmFeTeO}}_{ 6}{({\text{s}})} & \to {\text{SmFeO}}_{ 3} {( {\text{s}})} + {\text{TeO}}_{ 2} {( {\text{g}})} + \left( { 1/ 2} \right){\text{O}}_{ 2}{( {\text{g}})} \\ {\text{SmCrTeO}}_{ 6} {( {\text{s}})} & \to {\text{SmCrO}}_{ 3} {( {\text{s}})} + {\text{TeO}}_{ 2}{( {\text{g}})} + \left( { 1/ 2} \right){\text{O}}_{ 2}{( {\text{g}})}. \\ \end{aligned} $$ X-ray diffraction data of both the compounds have been indexed on the hexagonal system. Partial pressures of TeO2(g) were measured over SmFeO3(s) and SmCrO3(s) by employing the Knudsen effusion mass loss technique. The standard Gibbs free energy of formation of (Δf G°) SmFeTeO6(s) and SmCrTeO6(s) were obtained from partial pressures and represented by the following relations: $$\Updelta_{\text{f}} G^{\circ} \left( {{\text{SmFeTeO}}_{6}{( {{\text{s}},\,T})}} \right) \pm 2 5\,{\text{kJ}}\,{\text{mol}}^{ - 1} = - 1 5 1. 6 5+ 0. 1 5\left(T \right)\quad \left( 1 ,0 90{-} 1,1 80\,{\text{K}} \right) \\ \Updelta_{\text{f}} G^{\circ } \left( {{\text{SmCrTeO}}_{ 6} {( {{\text{s}},\,T})}} \right) \pm 2 5\,{\text{kJ}}\,{\text{mole}}^{ - 1} = - 2 5 2. 8 6+ 0. 1 2(T)\quad \left( { 1,100 {-} 1 , 1 7 5\,{\text{K}}} \right).$$ 相似文献
160.
Studies are presented on in-plane shear properties of a typical plain weave E-glass/epoxy composite under high strain rate loading. In-plane shear properties were determined with ±45 degree off-axis compression and tension tests using a split Hopkinson pressure bar apparatus. In-plane shear properties are presented as a function of axial and shear strain rates. The range of axial strain rates for off-axis compression tests was 819–2003 per sec, and for off-axis tension tests was 91–180 per sec, whereas the range of shear strain rates for off-axis compression tests was 1388–3442 per sec and for off-axis tension tests was 153–303 per sec. In general, it was observed that in-plane shear strength was enhanced at high strain rate loading compared to that at quasi-static loading. Also, it was observed that in-plane shear strength increased with increasing strain rate within the range of strain rates considered. 相似文献