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301.
D. Naveen Kumar 《Tetrahedron letters》2004,45(41):7713-7714
A chiron approach to a synthesis of (1R,2R,5S,7R)-2-hydroxy-exo-brevicomin 1, a component of the volatiles obtained from male mountain pine beetles, Dendroctonus ponderosae has been achieved. Our synthesis started with commercially available d-mannitol and involved Wittig olefination, acid catalysed one-pot hydrogenation and internal acetalization as key steps. 相似文献
302.
Liquid crystal thermography and pressure drop measurements have been carried out to study the heat transfer and frictional characteristics in a rectangular duct with solid ribs (C1), converging slit-ribs (C2), and alternate solid-slit ribs (C3) mounted transversely on the bottom wall, where C2 carries a continuous converging-slit in the flow direction. Effect of rib configurations, and rib pitch to height ratios (6, 8, 10, and 12) has been investigated at Re of 9400, 26160, 42500, and 58850. Results show that converging-slit considerably enhances the heat transfer rate in the downstream vicinity, and help in obviating the local hot spot formation.
Abbreviations: LCT: Liquid crystal thermography; HTC: Heat transfer coefficient; LHI: Laser holographic interferometry; NST: Naphthalene sublimation technique; IR: Infrared; TPF: Thermo-hydraulic performance; PIV: Particle image velocimetry. 相似文献
303.
S. Naveen Sridhar M. Anandalwar J. Shashidhara Prasad Dinesh Manvar Arun Mishra Anamik Shah 《Journal of chemical crystallography》2008,38(4):315-319
Abstract 2,6-Dimethyl-5-(phenylcarbamoyl)-4-(3-nitrophenyl)-1,4-dihydropyridine-2-carboxylate was synthesized in two steps and was
characterized spectroscopically and confirmed by X-ray diffraction studies. The molecule crystallizes in the monoclinic crystal
class in the spacegroup P21/c with cell parameters a = 10.5960(6) ?, b = 10.2450(7) ?, c = 19.5790(11) ?, β = 107.448(3)° and Z = 4. The 1,4-dihydropyridine ring in the structure adopts a flattened boat conformation.
Graphical Abstract 2,6-Dimethyl-5-(phenylcarbamoyl)-4-(3-nitrophenyl)-1,4-dihydropyridine-2-carboxylate was synthesized in two steps and was
characterized spectroscopically and confirmed by X-ray diffraction studies. The molecule crystallizes in the monoclinic crystal
class in the spacegroup P21/c with cell parameters a = 10.5960(6) ?, b = 10.2450(7) ?, c = 19.5790(11) ?, β = 107.448(3)° and Z = 4. The 1,4-dihydropyridine ring in the structure adopts a flattened boat conformation.
相似文献
304.
We report an efficient synthetic strategy to diverse hydantoins and thiohydantoins involving a three‐component reaction with the aid of deep eutectic solvent. Here, N,N′‐dimethyl urea and N,N′‐dimethyl thiourea play a dual role as reactant and reaction medium along with l ‐(+)‐tartaric acid. The three‐component reaction provides an easy access to 5‐amino‐1,3‐dialkyl‐substituted hydantoins and thiohydantoins in good yields. 相似文献
305.
Lallan Yadav Naveen Chandra Gupta R. Dwivedi Ravi S. Singh 《Microelectronics Journal》2007,38(12):1226-1232
A Pd/TiO2/Si MOS sensor (Pdtisin sensor) is proposed for the detection of hydrogen gas. The sensor is fabricated on a p-type 1 1 1 silicon wafer having resistivity of 3–6 Ω cm. The thickness of TiO2 in this structure is about 600 nm. The capacitance–voltage (C–V) and conductance–voltage (G–V) characteristics of the device is observed on the exposure of hydrogen gas at room temperature. The mechanism of hydrogen sensing of titanium dioxide-based MOS sensor (MOS capacitor) has been investigated by evaluating the change in flat-band voltage (VFB) and fixed surface state density of the device in presence of hydrogen gas. The device exhibits very large parallel shift in C–V as well in G–V characteristics. The possible mechanism on Pd/TiO2 and TiO2/Si surface in presence of hydrogen gas has been proposed. The response and recovery time of the device is also measured at room temperature. 相似文献
306.
Laksminarayana Rao Naveen Krishna Reddy Sylvain Coulombe Jean-Luc Meunier Richard J. Munz 《Journal of nanoparticle research》2007,9(4):689-695
This communication reports on a new method for the collection of nanoparticles using carbon nanotubes (CNT) as collecting
surfaces, by which the problem of agglomeration of nanoparticles can be circumvented. CNT (10–50 nm in diameter, 1–10 μm in
length) were grown by thermal CVD at 923 K in a 7 v/v% C2H2 in N2 mixture on electroless nickel-plated copper transmission electron microscopy (TEM) grids and Monel coupons. These samples
were then placed downstream of an arc plasma reactor to collect individual copper nanoparticles (5–30 nm in diameter). It
was observed that the Cu nanoparticles preferentially adhere onto CNT and that the macro-particles (diameter >1 μm), a usual
co-product obtained with metal nanoparticles in the arc plasma synthesis, are not collected. Cu–Ni nanoparticles, a catalyst
for CNT growth, were deposited on CNT to grow multibranched CNT. CNT-embedded thin films were produced by re-melting the deposited
nanoparticles. 相似文献
307.
Transport in Porous Media - The stability of double-diffusive buoyant flow in a vertical layer of Darcy porous medium whose boundaries are held at different constant temperatures and solute... 相似文献
308.
Aebisher D Azar NS Zamadar M Gandra N Gafney HD Gao R Greer A 《The journal of physical chemistry. B》2008,112(7):1913-1917
Singlet molecular oxygen [1O2 (1Deltag)] is generated cleanly in aqueous solution upon irradiation of a heterogeneous complex, meso-tetra(N-methyl-4-pyridyl)porphine (1) adsorbed onto porous Vycor glass (PVG). The cationic photosensitizer 1 tightly binds onto PVG and gives a stable material, which does not dissociate 1 into the surrounding aqueous phase. The production of 1O2 was measured by monitoring the time-resolved 1O2 (1Deltag) phosphorescence at 1270 nm. Indirect analysis of 1O2 generation was also carried out with the photooxidation of trans-2-methyl-2-pentenoate anion, which afforded the corresponding hydroperoxide. Sensitizer-1-impregnated PVG gives rise to a new singlet oxygen generator but more importantly provides a heterogeneous system for use in water. 相似文献
309.
Satish Shantaram Bhat Naveen Shivalingegowda Vidyanand Krishna Revankar Vitthal Ajinath Kawade Ray J. Butcher Neratur Krishnappagowda Lokanath 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(5):496-503
Two one‐dimensional (1D) coordination polymers (CPs), namely catena‐poly[[[aqua(2,2′‐bipyridine‐κ2N,N′)(nitrato‐κO)copper(II)]‐μ‐1,3‐bis(pyridin‐4‐yl)propane‐κ2N:N′] nitrate], {[Cu(NO3)(C10H8N2)(C13H14N2)(H2O)]·NO3}n ( 1 ), and catena‐poly[[[aqua(nitrato‐κO)(1,10‐phenanthroline‐κ2N,N′)copper(II)]‐μ‐1,3‐bis(pyridin‐4‐yl)propane‐κ2N:N′] nitrate], {[Cu(NO3)(C12H8N2)(C13H14N2)(H2O)]·NO3}n ( 2 ), have been synthesized using [Cu(NO3)(NN)(H2O)2]NO3, where NN = 2,2′‐bipyridine (bpy) or 1,10‐phenanthroline (phen), as a linker in a 1:1 molar ratio. The CPs were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis and single‐crystal X‐ray structure determination. The 1,3‐bis(pyridin‐4‐yl)propane (dpp) ligand acts as a bridging ligand, leading to the formation of a 1D polymer. The octahedral coordination sphere around copper consists of two N atoms from bpy for 1 or phen for 2 , two N atoms from dpp, one O atom from water and one O atom from a coordinated nitrate anion. Each structure contains two crystallographically independent chains in the asymmetric unit and the chains are linked via hydrogen bonds into a three‐dimensional network. 相似文献
310.
A unit cube in ${\mathbb{R}^k}$ (or a k-cube in short) is defined as the Cartesian product R 1 × R 2?× ... × R k where R i (for 1??? i??? k) is a closed interval of the form [a i , a i + 1] on the real line. A k-cube representation of a graph G is a mapping of the vertices of G to k-cubes such that two vertices in G are adjacent if and only if their corresponding k-cubes have a non-empty intersection. The cubicity of G is the minimum k such that G has a k-cube representation. From a geometric embedding point of view, a k-cube representation of G?=?(V, E) yields an embedding ${f: V(G) \rightarrow \mathbb{R}^k}$ such that for any two vertices u and v, ||f(u) ? f(v)||?? ?? 1 if and only if ${(u, v) \in E(G)}$ . We first present a randomized algorithm that constructs the cube representation of any graph on n vertices with maximum degree ?? in O(?? ln n) dimensions. This algorithm is then derandomized to obtain a polynomial time deterministic algorithm that also produces the cube representation of the input graph in the same number of dimensions. The bandwidth ordering of the graph is studied next and it is shown that our algorithm can be improved to produce a cube representation of the input graph G in O(?? ln b) dimensions, where b is the bandwidth of G, given a bandwidth ordering of G. Note that b ?? n and b is much smaller than n for many well-known graph classes. Another upper bound of b + 1 on the cubicity of any graph with bandwidth b is also shown. Together, these results imply that for any graph G with maximum degree ?? and bandwidth b, the cubicity is O(min{b, ?? ln b}). The upper bound of b?+ 1 is used to derive upper bounds for the cubicity of circular-arc graphs, cocomparability graphs and AT-free graphs in terms of the maximum degree ??. 相似文献