Results 201  250 of 1666  
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Edmonds Christopher M   2012
We investigate unforced and forced translocation of a Rouse polymer (in the absence of hydrodynamic interactions) through a silicon nitride nanopore by threedimensional Langevin dynamics simulations, as a function of pore dimensions and applied voltage. Our nanopore model consists of an atomistically detailed nanopore constructed using the crystal structure of ...


Friedrich R   2012
The effects of electronic states and air exposure on the spectroscopic properties of manganese phthalocyanine (MnPc) have been examined. The observed features of the Qband in the absorption spectra can be explained by intrinsic electronic properties of MnPc, i.e., the formation of singly charged molecules by charge transfer excitations. However, ...


Wood Brandon C   2012
We perform densityfunctional theory calculations on model surfaces to investigate the interplay between the morphology, electronic structure, and chemistry of oxygen and hydroxylrich surfaces of InP(001) and GaP(001). Four dominant local oxygen topologies are identified based on the coordination environment: MOM and MOP bridges for the oxygendecorated surface; and M[OH]M ...


Niu Kai   2012
The thirdorder polarization for coherent antiStokes Raman scattering (CARS) from a pure state is described by 48 terms in perturbation theory, but only 4 terms satisfy the rotating wave approximation. They are represented by Feynman dual timeline diagrams and fourwave mixing energy level diagrams. In timeresolved (tr) fs and fs/ps ...


Bruni F   2012
By combining neutron diffraction and Monte Carlo simulations, we have determined the microscopic structure of the hydration ions shell in aqueous solutions of MgCl(2) and CaCl(2), along with the radial distribution functions of the solvent. In particular the hydration shell of the cations, show cation specific symmetry, due to the ...


Tan Hong Kee   2012
It has been demonstrated in our studies that the intrinsic curvature of DNA can be easily interrupted by low concentrations of chloroquine and ethidium bromide. In addition, the changes of DNA curvature caused by varying the concentration of these two DNA intercalators can be readily verified through using an atomic ...


Jaeger Heather M   2012
Multiexciton generation (MEG), the creation of more than one electronhole pair per photon absorbed, occurs for excitation energies greater than twice the bandgap (E(g)). Imperfections on the surface of quantum dots, in the form of atomic vacancies or incomplete surface passivation, lead to less than ideal efficiencies for MEG in ...


Hartkamp Remco   2012
The transienttime correlation function (TTCF) method is used to calculate the nonlinear response of a homogeneous atomic fluid close to equilibrium. The TTCF response of the pressure tensor subjected to a timeindependent planar mixed flow of shear and elongation is compared to directly averaged nonequilibrium molecular dynamics (NEMD) simulations. We ...


Shew ChwenYang   2012
Several singlemodal Debye correlation functions to approximate part of the overall Debey correlation function of liquids are closely examined for elucidating their behavior in the corresponding spin echo small angle neutron scattering (SESANS) correlation functions. We find that the maximum length scale of a Debye correlation function is identical to ...


Experimental electron density of sumanene, a bowlshaped fullerene fragment; comparison with the ...
Mebs Stefan   2012
The experimental electron density of sumanene, C(21)H(12), was extracted from a high resolution Xray data set measured at 100 K and topologically analyzed. In addition to bond topological and atomic properties, information about the density distribution between adjacent molecules, which show close CC approaches of ∼3.4 Å within the columnar ...


Knippenberg S   2012
An earlier proposed approach to molecular response functions based on the intermediate state representation (ISR) of polarization propagator and algebraicdiagrammatic construction (ADC) approximations is for the first time employed for calculations of nonlinear response properties. The twophoton absorption (TPA) spectra are considered. The hierarchy of the first and secondorder ADC∕ISR ...


Eilam Asaf   2012
We propose a method based on the electromagnetically induced transparency (EIT) phenomenon for the detection of molecules which exist as a small minority in the presence of a majority of absorbers. The EIT effect we employ effectively eliminates the absorption of the majority species in the spectral region where it ...


Alexander Andrew J   2012
A protocol has been developed for production of intense crystalloluminescence (XTL) from sodium chloride in aqueous solution by selective doping with transition metal salts (Ag(+), Cu(2+), and Dy(3+)). The method was used to record complete, fully dispersed deep UVvisible (200650 nm) XTL spectra of sodium chloride for the first time. ...


Raghunathan Shampa   2012
Explicitly timedependent density functional theory (TDDFT) is a formally exact theory, which can treat very large systems. However, in practice it is used almost exclusively in the adiabatic approximation and with standard ground state functionals. Therefore, if combined with coherent control theory, it is not clear which control tasks can ...


Miura Tsuyoshi   2012
A fluorous organocatalyst promotes direct asymmetric aldol reactions of aromatic aldehydes with ketones in brine to afford the corresponding antialdol products in high yield with up to 96% ee. Fluorous organocatalyst can be readily recovered by solid phase extraction using fluorous silica gel and reused without purification.


Terada Tadashi   2012
Schneiderian papilloma (SP) is classified into three types: inverted, oncocytic, and exophytic. Malignant transformation occurs in 10% of SP; most are inverted and oncocytic types. Malignant transformation of polypoid exophytic SP is exceptional; only two cases have been reported in the English literature. A 58yearold man consulted our hospital because ...


Gaiduk Alex P   2012
The common way to obtain energies from KohnSham exchange potentials is by using the LevyPerdew virial relation. For potentials that are not functional derivatives (i.e., nearly all model exchange potentials in existence), this approach leads to energy expressions that lack translational and rotational invariance. We propose a method for constructing ...


Reva Igor   2012
Spontaneous and nearinfrared∕infrared (NIR∕IR)induced interconversions between two aminohydroxy conformers of monomeric cytosine have been investigated for the compound isolated in a lowtemperature argon matrix. Combined use of a laser source (which provides narrowband NIR radiation) and a broadband NIR/IR source of excitation light allowed a detailed investigation of mutual conversions ...


Tonge Nicola M   2012
We report the first spectroscopic study of a complex consisting of a rare earth atom in combination with ammonia. Using twocolor resonanceenhanced multiphoton ionization (REMPI) spectroscopy, the lowest energy electronic transition of YbNH(3) has been found in the nearinfrared. The spectrum arises from a spinforbidden transition between the (1)A(1) ground ...


Shin Hyeondeok   2012
Pathintegral Monte Carlo calculations have been performed to study (4)He adsorption on a single C(60) molecule. Helium corrugations on the fullerene molecular surface are incorporated with the (4)HeC(60) interaction described by the sum of all (4)HeC interatomic pair potentials. Radial density distributions show a layerbylayer growth of (4)He with the ...


Silverstein Daniel W   2012
A vibronic coupling model based on timedependent wavepacket approach is applied to simulate linear optical processes, such as onephoton absorbance and resonance Raman scattering, and nonlinear optical processes, such as twophoton absorbance and resonance hyperRaman scattering, on a series of small molecules. Simulations employing both the longrange corrected approach in ...


Thilagam A   2012
The nonHermitian quantum dynamics of excitonic energy transfer in photosynthetic systems is investigated using a dissipative twolevel dimer model. The approach is based on Green's function formalism which permits consideration of decoherence and intersite transfer processes on comparable terms. The results indicate a combination of coherent and incoherent behavior at ...


Santosh Mogurampelly   2012
In an effort to design efficient platform for siRNA delivery, we combine all atom classical and quantum simulations to study the binding of small interfering RNA (siRNA) by pristine single wall carbon nanotube (SWCNT). Our results show that siRNA strongly binds to SWCNT surface via unzipping its basepairs and the ...


Birzniece I   2012
The diode laser induced B(1)(1)Π → X(1)Σ(+) fluorescence spectra of the KCs molecule were recorded by Fouriertransform spectrometer with resolution of 0.03 cm(1). Buffer gas Ar was used to facilitate appearance of rotation relaxation lines in the spectra, thus enlarging the B(1)(1)Π dataset, allowing one to determine the Λsplitting constants ...


Cajahuaringa Samuel   2012
We use molecular simulation to analyze liquid dynamics in the vicinity of the liquidliquid phase transition (LLPT) recently discovered in the modified embeddedatom model for elemental gallium. For this purpose we analyze the diffusive behavior in terms of the meansquared displacement and selfintermediate scattering functions for two systems obtained by ...


Stephens Susanna L   2012
Pure rotational spectra of the ground vibrational states of six isotopologues of OC⋅⋅⋅AgI have been measured by chirpedpulse Fourier transform microwave spectroscopy. The spectra are assigned to determine the rotational constant, B(0), centrifugal distortion constant, D(J), and nuclear quadrupole coupling constant of the iodine atom, χ(aa)(I). The complex is linear. ...


Calandra Pietro   2012
This work focuses on the dynamic phenomena emerging in selfassembled transient intermolecular networks formed when two different surfactants are mixed. In particular, the relaxation processes in liquid mixtures composed by bis(2ethylhexyl)amine (BEEA) and octanoic acid (OA) in the whole composition range has been investigated by dielectric spectroscopy and Brillouin spectroscopy. ...


Groot Robert D   2012
Longrange hydrodynamics between colloidal particles or fibers is modelled by the fluid particle model. Two methods are considered to impose the fluid boundary conditions at colloidal surfaces. In the first method radial and transverse friction forces between particle and solvent are applied such that the correct friction and torque follows ...


Kawata Isao   2012
A new method for analyzing and visualizing the molecular excited states, named "excited state paired interacting orbital (EPIO)," is proposed. The method is based both on the paired interacting orbital (PIO) proposed by Fujimoto and Fukui [J. Chem. Phys. 60, 572 (1974)] and the natural transition orbital (NTO) by Martin ...


Li Huashan   2012
Transition state analyses have been carried out within a density functional theory setting to explain and quantify the distinctly different ways in which hydrogen and methyl terminations serve to protect silicon surfaces from the earliest onset of oxidation. We find that oxidation occurs via direct dissociative adsorption, without any energy ...


Navin J K   2012
Effusive molecular beam measurements of angleresolved thermal dissociative sticking coefficients for CH(4) impinging on a Pt(111) surface, at a temperature of 700 K, are reported and compared to theoretical predictions. The reactivity falls off steeply as the molecular angle of incidence increases away from the surface normal. Successful modeling of ...


Adams Christopher L   2012
We present lowenergy velocity map photoelectron imaging results for bare and Arsolvated 1nitropropane and 1nitrobutane anions. We report the adiabatic electron affinity of 1nitropropane as (223 ± 6) meV and that of 1nitrobutane as (240 ± 6 meV). The vertical detachment energies of these two species are found to be ...


Zhang Bo   2012
We have used density functional theory (DFT) employing several different exchangecorrelation functionals (PW91, PBE, PBEsol, TPSS, and revTPSS) coupled with lattice dynamics calculations to compute the thermodynamics of CO(2) absorption∕desorption reactions for selected transition metal oxides, (TMO), and hydroxides, TM(OH)(2), where TM = Mn, Ni, Zn, and Cd. The van't ...


Silverstein Daniel W   2012
A comprehensive vibronic coupling model based on the timedependent wavepacket approach is derived to simulate linear optical processes, such as onephoton absorbance and resonance Raman scattering, and nonlinear optical processes, such as twophoton absorbance and resonance hyperRaman scattering. This approach is particularly well suited for combination with firstprinciples calculations. Expressions ...


Ryabov Artem   2012
We investigate a diffusive motion of a system of interacting Brownian particles in quasionedimensional micropores. In particular, we consider a semiinfinite 1D geometry with a partially absorbing boundary and the hardcore interparticle interaction. Due to the absorbing boundary the number of particles in the pore gradually decreases. We present the ...


Miao Meng   2012
Using firstprinciples calculations we have studied the reactions of water over Ti adatoms on the (110) surface of rutile TiO(2). Our results provide fundamental insights into the microscopic mechanisms that drive this reaction at the atomic level and assess the possibility of using this system to activate the water dissociation ...


Dudowicz Jacek   2012
The lattice cluster theory (LCT) for the thermodynamics of a wide array of polymer systems has been developed by using an analogy to Mayer's virial expansions for nonideal gases. However, the hightemperature expansion inherent to the LCT has heretofore precluded its application to systems exhibiting strong, specific "sticky" interactions. The ...


Sabass Benedikt   2012
Active diffusiophoresisswimming through interaction with a selfgenerated, neutral, solute gradientis a paradigm for autonomous motion at the micrometer scale. We study this propulsion mechanism within a linear response theory. First, we consider several aspects relating to the dynamics of the swimming particle. We extend established analytical formulae to describe small ...


Philpott Michael R   2012
The three step auf bau of a triangular polyaromatic protrusion attached to a larger parent hexagonal shaped graphene nanodot (GND) is described and the dichotomy between intrinsic protrusion localized magnetism and parent extended zigzag edge magnetism is explored using ab initio density functional theory calculations of spin and charge distributions ...


Huang Jing   2012
We investigate the spin transport properties of ironphthalocyanine (FePc) molecule sandwiched between two Ndoped graphene nanoribbons (GNRs) based on the density functional theory and nonequilibrium Green's function methods. Our calculated results clearly reveal that the FePc molecular junction has high spinfilter efficiency as well as negative differential resistance (NDR). The ...


Huntington Lee M J   2012
We have recently introduced a parameterized coupledcluster singles and doubles model (pCCSD(α, β)) that consists of a bivariate parameterization of the CCSD equations and is inspired by the coupled electron pair approximations. In our previous work, it was demonstrated that the pCCSD(1, 1) method is an improvement over CCSD for ...


Shao Zhuo   2012
The energy levels of CH(3)Cl(+)X̃(2)E showing strong spinvibronic coupling effect (JahnTeller effect) have been measured up to 3500 cm(1) above the ground vibrational state using onephoton zerokinetic energy photoelectron and massanalyzed threshold ionization spectroscopic method. Theoretical calculations have been also performed to calculate the spinvibronic energy levels using a diabatic ...


Huggins David J   2012
Water is one of the simplest molecules in existence, but also one of the most important in biological and engineered systems. However, understanding the structure and dynamics of liquid water remains a major scientific challenge. Molecular dynamics simulations of liquid water were performed using the water models TIP3PEwald, TIP4P2005, TIP5PEwald, ...


Kuo YingJu   2012
Prostate cancer has seen a rapid rise in Taiwanese men. The current study was undertaken to evaluate trends of the disease diagnosed on prostate needle biopsy during a tenyear period at the Department of Pathology, Taipei Veterans General Hospital. The study included 8236 men who underwent a total of 9995 ...


Vilar Jose M G   2012
Many important processes at the microscale require farfromequilibrium conditions to occur, as in the functioning of mesoscopic bioreactors, nanoscopic rotors, and nanoscale mass conveyors. Achieving such conditions, however, is typically based on energy inputs that strongly affect the thermal properties of the environment and the controllability of the system itself. ...


SwiatlaWojcik Dorota   2012
Flexible models of the radical and water molecules including shortrange interaction of hydrogen atoms have been employed in molecular dynamic simulation to understand mechanism of (●)OH hydration in aqueous systems of technological importance. A key role of Hbond connectivity patterns of water molecules has been identified. The behavior of (●)OH(aq) ...


Andreussi Oliviero   2012
The solvation model proposed by Fattebert and Gygi [J. Comput. Chem. 23, 662 (2002)] and Scherlis et al. [J. Chem. Phys. 124, 074103 (2006)] is reformulated, overcoming some of the numerical limitations encountered and extending its range of applicability. We first recast the problem in terms of induced polarization charges ...


Iuchi Satoru   2012
A simple model electronic Hamiltonian to describe the potential energy surfaces of several lowlying dd states of the [Fe(bpy)(3)](2+) complex is developed for use in molecular dynamics (MD) simulation studies. On the basis of a method proposed previously for firstrow transition metal ions in aqueous solution, the model Hamiltonian is ...


Napolitano José G   2012
Botanical dietary supplements and herbal remedies are widely used for health promotion and disease prevention. Due to the high chemical complexity of these natural products, it is essential to develop new analytical strategies to guarantee their quality and consistency. In particular, the precise characterization of multiple botanical markers remains a ...


Köck Matthias M AlfredWegenerInstitut für Polar und Meeresforschung in der HelmholtzGemeinschaft, Am Handelshafen 12, D27570 Bremerhaven, Germany.   2012
The structure elucidation of the palau'amine congener tetrabromostyloguanidine (1), which used interproton distances from ROESY spectra as restraints in a computational approach, the socalled fcrDG/DDD method, led to a revision of the relative configuration of palau'amine (2) and its congeners in 2007. The recent total synthesis of (±)palau'amine (2) subsequently ...


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