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991.
B. Krishna Das J. Martin Lindsay Orawan Tripak 《Journal of Mathematical Analysis and Applications》2014
A theory of quantum stochastic processes in Banach space is initiated. The processes considered here consist of Banach space valued sesquilinear maps. We establish an existence and uniqueness theorem for quantum stochastic differential equations in Banach modules, show that solutions in unital Banach algebras yield stochastic cocycles, give sufficient conditions for a stochastic cocycle to satisfy such an equation, and prove a stochastic Lie–Trotter product formula. The theory is used to extend, unify and refine standard quantum stochastic analysis through different choices of Banach space, of which there are three paradigm classes: spaces of bounded Hilbert space operators, operator mapping spaces and duals of operator space coalgebras. Our results provide the basis for a general theory of quantum stochastic processes in operator spaces, of which Lévy processes on compact quantum groups is a special case. 相似文献
992.
Peilin Yang George R. Litwinski Matthias Pursch Terry McCabe Krishna Kuppannan 《Journal of separation science》2009,32(11):1816-1822
Three HPLC columns packed with 3 μm, sub‐2 μm, and 2.7 μm Fused‐Core (superficially porous) particles were compared in separation performance using two natural product mixtures containing 15 structurally related components. The Ascentis ExpressTM C18 column packed with Fused‐Core particles showed an 18% increase in column efficiency (theoretical plates), a 76% increase in plate number per meter, a 65% enhancement in separation speed and a 19% increase in back pressure compared to the Atlantis T3TM C18 column packed with 3 μm particles. Column lot‐to‐lot variability for critical pairs in the natural product mixture was observed with both columns, with the Atlantis T3 column exhibiting a higher degree of variability. The Ascentis Express column was also compared with the AcquityTM BEH column packed with sub‐2 μm particles. Although the peak efficiencies obtained by the Ascentis Express column were only about 74% of those obtained by the Acquity BEH column, the 50% lower back pressure and comparable separation speed allowed high‐efficiency and high‐speed separation to be performed using conventional HPLC instrumentation. 相似文献
993.
Density functional theory calculations have been performed for the title phosphinidene complexes using the exchange correlation functionals BP86 and B3LYP. The optimized bond lengths and angles of the model compounds are in excellent agreement with experiment. The M-P bond lengths in linear phosphinidene complexes correspond to a Pauling bond order of ∼ 3. The bent geometries at phosphorus in the bent metal phosphinidene complexes are consistent with the presence of a trivalent phosphorus(III) center which is singly bonded to carbon and doubly bonded to transition metal. The analysis of the delocalized Kohn-Sham orbitals shows the polarization of the M-P σ bonding orbitals towards the phosphorus atom in the MPMe bonds, while in the MPMe bond, the contributions of metal and phosphorus are almost the same. In the linear phosphinidene complexes the contributions of the covalent bonding ΔEorb are more than the electrostatic interaction ΔEelstat. The bent phosphinidene complexes have a lower degree of covalent bonding than the linear phosphinidene complexes. The major differences between the linear and bent phosphinidene complexes are found in the degree of π-bonding. The MPMe bonds show a true M-P π bond and a deviated π bond due to slight bent M-P-C bond angles. The MPMe bonds show a true M-P π bond and a lone-pair on phosphorus. 相似文献
994.
de Leeuw NH Catlow CR King HE Putnis A Muralidharan K Deymier P Stimpfl M Drake MJ 《Chemical communications (Cambridge, England)》2010,46(47):8923-8925
The presence of water in the Earth has long been an enigma. However, computer modelling techniques have shown that the adsorption of water onto the fractal surfaces of interplanetary dust particles, which are present in the planetary accretion disk, is sufficiently strong to provide a viable origin of terrestrial water. 相似文献
995.
Takami T Ye T Pathem BK Arnold DP Sugiura K Bian Y Jiang J Weiss PS 《Journal of the American Chemical Society》2010,132(46):16460-16466
We have used a scanning tunneling microscope (STM) to manipulate heteroleptic phthalocyaninato, naphthalocyaninato, and porphyrinato double-decker (DD) molecules at the liquid-solid interface between 1-phenyloctane solvent and graphite. We employed nanografting of phthalocyanines with eight octyl chains to place these molecules into a matrix of heteroleptic DD molecules; the overlayer structure is epitaxial on graphite. We have also used nanografting to place DD molecules in matrices of single-layer phthalocyanines with octyl chains. Rectangular scans with a STM at low bias voltage resulted in the removal of the adsorbed DD molecular layer and substituted the DD molecules with bilayer-stacked phthalocyanines from phenyloctane solution. Single heteroleptic DD molecules with lutetium sandwiched between naphthalocyanine and octaethylporphyrin were decomposed with voltage pulses from the probe tip; the top octaethylporphyrin ligand was removed, and the bottom naphthalocyanine ligand remained on the surface. A domain of decomposed molecules was formed within the DD molecular domain, and the boundary of the decomposed molecular domain self-cured to become rectangular. We demonstrated a molecular "sliding block puzzle" with cascades of DD molecules on the graphite surface. 相似文献
996.
Joaudimir Castro M. V. Balarama Krishna John R. Choiniere R. Kenneth Marcus 《Analytical and bioanalytical chemistry》2010,396(3):1259-1271
A liquid chromatography–particle beam/mass spectrometry (LC–PB/MS) method with electron impact (EI) and glow discharge (GD)
ionization sources is presented for the determination of caffeic acid derivatives in echinacea tinctures. In this work, two
commercially available echinacea ethanolic extracts were used as the test samples for the separation, identification, and
quantification of the caffeic acid derivatives (caffeic acid, chlorogenic acid, cichoric acid, and caftaric acid), which are
suggested to have beneficial medicinal properties. Detailed evaluations of the two primary controlling parameters for EI (electron
energy and source block temperature) and GD (discharge current and pressure) sources were performed to determine optimal instrument
operation conditions. The mass spectra obtained from both ion sources provide clear and simple molecular fragmentation patterns
for each of the target analytes. The absolute detection limits for the caffeic acid derivatives were determined to be at subnanogram
levels for both the EI and GD sources. The separation of the caffeic acid derivatives in echinacea was accomplished by reversed-phase
chromatography using a C18 column and a gradient elution system of water containing 0.1% trifluoroacetic acid and methanol, with an analysis time of
less than 40 min. A standard addition method was employed for the quantification of each of the caffeic acid derivatives in
the tincture. 相似文献
997.
Andrea GeltrudeKais Al Naimee Stefano EuzzorRiccardo Meucci Fortunato Tito Arecchi Binoy Krishna Goswami 《Communications in Nonlinear Science & Numerical Simulation》2012,17(7):3031-3039
With a modulated CO2 laser as a standard model of periodically driven multistable systems, we experimentally demonstrate that a small-amplitude optoelectronic feedback perturbation can efficiently transform a bursting chaotic system to a nonchaotic one. Numerical simulations are in excellent agreement with the experimental results. The control has also been equally effective in the case of a driven FitzHugh-Nagumo model of Neuroscience. 相似文献
998.
Adepu R Rambabu D Prasad B Meda CL Kandale A Krishna GR Reddy CM Chennuru LN Parsa KV Pal M 《Organic & biomolecular chemistry》2012,10(29):5554-5569
Novel thieno[2,3-d]pyrimidines containing a cyclohexane ring fused with a six- or five-membered heterocyclic moiety along with a benzylic nitrile were designed as potential inhibitors of PDE4. Expeditious synthesis of these compounds was carried out via a multi-step sequence consisting of a few key steps such as Gewald reaction, Dieckmann type cyclisation and Krapcho decarboxylation. This newly developed strategy involved construction of the thienopyrimidine ring followed by the cyclohexanone moiety and subsequently the fused heterocyclic ring. A number of thieno[2,3-d]pyrimidine based derivatives were synthesized using this method some of which showed promising PDE4B inhibitory properties. One of them was tested for PDE4D inhibition in vitro and dose dependent inhibition of TNF-α. A few selected molecules were docked into the PE4B protein the results of which showed good overall correlations to their observed PDE4B inhibitory properties in vitro. The crystal structure analysis of representative compounds along with hydrogen bonding patterns and molecular arrangement present within the molecule is described. 相似文献
999.
A short and efficient approach to a 4-methylene-2-cyclohexenone substructure present in otteliones and loloanolides is described. This strategy involves a tandem enyne/ring closing metathesis as the key reaction to construct this labile core unit. 相似文献
1000.
Ch. Rajyasree P. Srinivasa Rao P.M. Vinaya Teja A. Ramesh Babu S. Yusub D. Krishna Rao 《Journal of Non》2012,358(18-19):2597-2605
Transparent glasses of composition 10BaO.20Bi2O3.(70 ? x)B2O3.xFe2O3 (wt.%) where 0 ≤ x ≤ 2.0, were characterized by XRD and SEM. Physical, spectroscopic and dielectric properties were investigated. At higher dopant of Fe2O3, EPR results revealed that, the number of Fe3+ ions participate in the resonance is decreased by forming a new signal at g ≈ 3.015 due to increase of antiferromagnetic interaction of Fe3+ ions and/or formation of low spin Fe3+ ions in the glass matrix. With initial 0.5 wt.% doping of Fe2O3, less dense glass is formed with colloids of metallic Bi0 atoms. The absorption bands at 604 and 712 nm in F5 glass are ascribed to Bi0 and Bi+ radicals respectively. No characteristic Fe3+ absorption bands (spin-forbidden) are found. Fe2+ ions are increased at higher concentration of Fe2O3. Higher concentration of Fe2O3 is favorable for BO2O?, BO3, BiO6 and FeO6 symmetry unit leads to low band gap and high Urbach energy. By doping of Fe2O3 the dielectric parameters like dielectric constant (ε′), loss (tanδ and ac electrical conductivity (σac) are found to increase. 相似文献