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211.
Raj Bali 《International Journal of Theoretical Physics》2009,48(2):476-486
Bianchi Type V magnetized string dust bulk viscous fluid cosmological model with variable magnetic permeability, is investigated.
The magnetic field is due to an electric current produced along x-axis. Thus the magnetic fields is in yz-plane and F
23 is the only non-vanishing component of electromagnetic field tensor F
ij
. To get the deterministic model in terms of cosmic time t, we have also assumed the condition ζ
θ=constant where ζ the coefficient of bulk viscosity and θ the expansion in the model. The behaviour of the model in presence and absence of magnetic field and bulk viscosity and singularities
in the model are also discussed.
相似文献
212.
R. Malathi G. Anitha K. Anand Solomon G. Suresh S. S. Rajan S. Narasimhan J. Josepha Lourdu Raj Geetha Gopalakrishnan 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(2):o70-o72
Nimbolide [systematic name: (4α,5α,6α,7α,15β,17α)‐7,15:21,23‐diepoxy‐6‐hydroxy‐4,8‐dimethyl‐1‐oxo‐18,24‐dinor‐11,12‐secochola‐2,13,20,22‐tetraene‐4,11‐dicarboxylic acid γ‐lactone methyl ester], C27H30O7, was isolated from the leaves of Azadirachta indica, and its isomer, isonimbolide [systematic name: (4α,5α,6α,7α,15α)‐7,15:21,23‐diepoxy‐6‐hydroxy‐4,8‐dimethyl‐1‐oxo‐18,24‐dinor‐11,12‐secochola‐2,16,20,22‐tetraene‐4,11‐dicarboxylic acid γ‐lactone methyl ester], was prepared from a novel rearrangement reaction of nimbolide, using boron trifluoride etherate and tetrabutylammonium bromide. The reaction conditions are probably responsible for the ether cleavage, double‐bond rearrangement and reformation of the ether linkage. As a result, there are conformational changes in two cyclopentane rings and the side‐chain –CH2COOMe group. In isonimbolide, an (24) hydrogen‐bond motif is observed. 相似文献
213.
Isci A Himmelsbach JN Strohl J Pometto AL Raman DR Anex RP 《Applied biochemistry and biotechnology》2009,157(3):453-462
Aqueous-ammonia-steeped switchgrass was subject to simultaneous saccharification and fermentation (SSF) in two pilot-scale
bioreactors (50- and 350-L working volume). Switchgrass was pretreated by soaking in ammonium hydroxide (30%) with solid to
liquid ratio of 5 L ammonium hydroxide per kilogram dry switchgrass for 5 days in 75-L steeping vessels without agitation
at ambient temperatures (15 to 33 °C). SSF of the pretreated biomass was carried out using Saccharomyces cerevisiae (D5A) at approximately 2% glucan and 77 filter paper units per gram cellulose enzyme loading (Spezyme CP). The 50-L fermentation
was carried out aseptically, whereas the 350-L fermentation was semiaseptic. The percentage of maximum theoretical ethanol
yields achieved was 73% in the 50-L reactor and 52–74% in the 350-L reactor due to the difference in asepsis. The 350-L fermentation
was contaminated by acid-producing bacteria (lactic and acetic acid concentrations approaching 10 g/L), and this resulted
in lower ethanol production. Despite this problem, the pilot-scale SSF of aqueous-ammonia-pretreated switchgrass has shown
promising results similar to laboratory-scale experiments. This work demonstrates challenges in pilot-scale fermentations
with material handling, aseptic conditions, and bacterial contamination for cellulosic fermentations to biofuels. 相似文献
214.
Dheerendra Yadav Varun Gupta Raj K. Thareja 《Spectrochimica Acta Part B: Atomic Spectroscopy》2009,64(10):986-992
The temporal evolution and spatial distribution of C2 molecules produced by laser ablation of a graphite target is studied using optical emission spectroscopy, dynamic imaging and laser-induced fluorescence (LIF) investigations. We observe peculiar bifurcation of carbon plume into two parts; stationary component close to the target surface and a component moving away from the target surface which splits further in two parts as the plume expands. The two distinct plumes are attributed to recombination of carbon species and formation of nanoparticles. The molecular carbon C2 moves with a faster velocity and dies out at ~ 800 ns whereas the clusters of nanoparticle move with a slower velocity due to their higher mass and can be observed even after 1600 ns. C2 molecules in the d3Πg state were probed for laser-induced fluorescence during ablation of graphite using the Swan (0,0) band at 516.5 nm. The fluorescence spectrum and images of fluorescence d3Πg − a3Πu(0,1)(λ = 563.5 nm) are recorded using a spectrograph attached to the ICCD camera. To get absolute ground state C2 density from fluorescence images, the images are calibrated using complimentary absorption experiment. This study qualitatively helps to get optimum conditions for nanoparticle formation using the laser ablation of graphite target and hence deducing optimum conditions for thin film deposition. 相似文献
215.
C. Yohannan Panicker Hema Tresa Varghese Asha Raj K. Raju Tugba Ertan-Bolelli Ilkay Yildiz Ozlem Temiz-Arpaci Carlos M. Granadeiro Helena I.S. Nogueira 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,74(1):132-139
The FT-IR and FT-Raman spectra of 2-phenoxymethylbenzothiazole were recorded and analyzed. The surface enhanced Raman scattering (SERS) spectrum was recorded in a silver colloid. The vibrational wavenumbers of the compound have been computed using the Hartree–Fock/6-31G* basis and compared with the experimental values. The appearance of the Ag–O stretching mode at 237 cm−1 in the SERS spectrum along with theoretically calculated atomic charge density, leads us to suggest that the molecule is adsorbed through the oxygen atom with the molecular plane tilted on the colloidal silver surface. The direction of charge transfer contribution to SERS has been discussed from the frontier orbital theory. 相似文献
216.
Fabrice Chevalier Deepak DSouza M. Raj Mohan Pavithra Prabhakar 《Annals of Pure and Applied Logic》2009,161(3):324-336
We extend some of the classical connections between automata and logic due to Büchi (1960) [5] and McNaughton and Papert (1971) [12] to languages of finitely varying functions or “signals”. In particular, we introduce a natural class of automata for generating finitely varying functions called ’s, and show that it coincides in terms of language definability with a natural monadic second-order logic interpreted over finitely varying functions Rabinovich (2002) [15]. We also identify a “counter-free” subclass of ’s which characterise the first-order definable languages of finitely varying functions. Our proofs mainly factor through the classical results for word languages. These results have applications in automata characterisations for continuously interpreted real-time logics like Metric Temporal Logic (MTL) Chevalier et al. (2006, 2007) [6] and [7]. 相似文献
217.
Amplitude and phase analysis in digital dynamic holography 总被引:1,自引:0,他引:1
Lensless in-line digital holographic interferometry has the potential for vibration analysis of objects smaller than 5 mm in diameter. This is particularly useful for dynamic characterization of microelectromechanical systems devices. To achieve this, there is a need to magnify the object wave, which is done using a diverging beam. It is observed that an increase in the object-to-CCD distance increases the sensitivity of the amplitude-modulated time-average fringes. At the same time the effect on phase information that represents the mean static deformation of a vibrating object is studied. It is also observed that a reduction in the object-to-CCD distance increases the phase sensitivity as evidenced by the double-exposure time-average fringes. The experimental observation and a theoretical explanation for this contradictory phenomenon are presented. 相似文献
218.
Boris Rajčić Silvana B. Dimitrijević Marijana Petković Marija Nišavić Mario Cindrić Filip Veljković Suzana Veličković 《Optical and Quantum Electronics》2018,50(5):218
In this work, a simple way for study the possibility of formation a vapor cluster species of tetrachloroauric acid (HAuCl4), using the laser ablation in the absence of a buffer or reactive atmosphere, and without a postablation supersonic expansion on a commercial matrix assisted laser desorption/ionization time-of-flight mass spectrometer, is reported. Tetrachloroauric acid is known as precursor for the synthesis of gold nanostructures and the complex salts; therefore it is an important task to discover and quantify the species arising from HAuCl4, in order to understand their role in the gold assisted reactions. Mass spectrum of HAuCl4 in a reflector negative-ion mode contains the hydrated mono- and dinuclear gold clusters in the m/z range 286–436, and gold chloride clusters in the m/z range 447–795. In the first part of spectrum, m/z range 286–436, the hydrated gold cluster species of type Au n ? (H2O)m (n?=?1–2; m?=?1, 2, 5, 7, 8) and [Aun(OH)k]?(H2O)m (n?=?1–2; k?=?1–2; m?=?1, 4–8) were found. Besides that, there are gold chloride clusters with general formula [AuHr(HCl)2]?(H2O)m (m?=?1–5; 8–9; r?=?0–2) in this part of spectrum. In the second part of spectrum, the m/z range 447–795, only gold chloride clusters were obtained. Their general formulae can be written as [AuClt(HCl)v]?(H2O)m (t?=?1–4; v?=?5–8; m?=?2–4, 6–8) and [Aun(HCl)v]?(H2O)m (n?=?1–2, v?=?4–5, m?=?1–2, 5, 7). The analysis of concentration effects on the LDI mass spectra of gold clusters reveals that the relative intensities of signals for the mono- and dinuclear Au clusters increase with decreasing the concentration of water HAuCl4 solutions. 相似文献
219.
Pure and urea-doped gamma-glycine (γ-glycine) single crystals were grown by solution method with slow evaporation technique. When urea was added as dopant, morphological alterations were noticed in γ-glycine crystals. Structural characterization of the grown crystals was carried out by single and powder X-ray diffraction (XRD) methods and it is observed that the samples crystallize in non-centrosymmetric space groups. UV-visible transmittance studies were performed to analyse optical transparency of pure and urea-doped γ-glycine crystals and found that the crystals were transparent in the entire visible-NIR region. Density and melting point of the grown crystals were measured. Second harmonic generation (SHG) for the grown crystals of this work was confirmed using Nd:YAG laser. Thermogravimetric and differential thermal analyses (TG/DTA) thermograms reveal that the materials have good thermal stability. From Microhardness studies, it is observed that urea-doped γ-glycine crystal is harder than pure (undoped) sample. 相似文献
220.