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norskArtikler, rapporter og annet (kjemi): Recent submissions
Now showing items 481-500 of 565
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Relativistic four-component calculations of indirect nuclear spin-spin couplings with efficient evaluation of the exchange-correlation response kernel
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-03-16)In this work, we report on the development and implementation of a new scheme for efficient calculation of indirect nuclear spin-spin couplings in the framework of four-component matrix Dirac-Kohn-Sham approach termed matrix Dirac-Kohn-Sham restricted magnetic balance resolution of identity for J and K, which takes advantage of the previous restricted magnetic balance formalism and the density ... -
Chemometric analysis for pollution source assessment of harbour sediments in Arctic locations
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-04-16)Pollution levels, pollutant distribution and potential source assessments based on multivariate analysis (chemometrics) were made for harbour sediments from two Arctic locations; Hammerfest in Norway and Sisimiut in Greenland. High levels of heavy metals were detected in addition to organic pollutants. Preliminary assessments based on Principal Component Analysis (PCA) revealed different sources and ... -
Multivariate methods for evaluating the efficiency of electrodialytic removal of heavy metals from polluted harbour sediments
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-02-11)Chemometrics was used to develop a multivariate model based on 46 previously reported electrodialytic remediation experiments (EDR) of five different harbour sediments. The model predicted final concentrations of Cd, Cu, Pb and Zn as a function of current density, remediation time, stirring rate, dry/wet sediment, cell set-up as well as sediment properties. Evaluation of the model showed that ... -
Cold shock induction of recombinant Arctic environmental genes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-08-19)Background: Heterologous expression of psychrophilic enzymes in E. coli is particularly challenging due to their intrinsic instability. The low stability is regarded as a consequence of adaptation that allow them to function at low temperatures. Recombinant production presents a significant barrier to their exploitation for commercial applications in industry. <p>Methods: As part of an enzyme ... -
Four-Component Relativistic Density-Functional Theory Calculations of Nuclear Spin-Rotation Constants: Relativistic Effects in p-Block Hydrides
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-07-01)We present an implementation of the nuclear spin–rotation (SR) constants based on the relativistic four-component Dirac–Coulomb Hamiltonian. This formalism has been implemented in the framework of the Hartree–Fock and Kohn–Sham theory, allowing assessment of both pure and hybrid exchange–correlation functionals. In the density-functional theory (DFT) implementation of the response equations, a ... -
Comparison of 2-compartment, 3-compartment and stack designs for electrodialytic removal of heavy metals from harbour sediments
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-01)Comparisons of cell and stack designs for the electrodialytic removal of heavy metals from two harbour sediments, were made. Multivariate modelling showed that sediment properties and experimental set-ups had the highest influence on the heavy metal removal indicating that they should be modelled and analysed separately. Clean-up levels of Cu, Pb and Zn were significantly higher for the cell designs, ... -
Excitation Energies from Real-Time Propagation of the Four-Component Dirac–Kohn–Sham Equation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-01-21)We report the first implementation of real-time time-dependent density functional theory (RT-TDDFT) at the relativistic four-component level of theory. In contrast to the perturbative linear-response TDDFT approach (LR-TDDFT), the RT-TDDFT approach performs an explicit time propagation of the Dirac–Kohn–Sham density matrix, offering the possibility to simulate molecular spectroscopies involving ... -
X-ray absorption resonances near L2,3-edges from real-time propagation of the Dirac–Kohn–Sham density matrix
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-08-07)The solution of the Liouville–von Neumann equation in the relativistic Dirac–Kohn–Sham density matrix formalism is presented and used to calculate X-ray absorption cross sections. Both dynamical relaxation effects and spin–orbit corrections are included, as demonstrated by calculations of the X-ray absorption of SF6 near the sulfur L2,3-edges. We also propose an analysis facilitating the interpretation ... -
Real-space numerical grid methods in quantum chemistry
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-03) -
Degradation of oil products in a soil from a Russian Barents hot‑spot during electrodialytic remediation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-02-24)A highly oil-polluted soil from Krasnoe in North-West Russia was used to investigate the degradation of organic pollutants during electrodialytic remediation. Removal efficiencies were up to 70 % for total hydrocarbons (THC) and up to 65 % for polyaromatic hydrocarbons (PAH). Relatively more of the lighter PAH compounds and THC fractions were degraded. A principal component analysis (PCA) revealed ... -
Note: Derivation of two-photon circular dichroism - Addendum to "two-photon circular dichroism" [J. Chem. Phys. 62, 1006 (1975)]
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-09-02)This addendum shows the detailed derivation of the fundamental equations for two-photon circular dichroism which are given in a very condensed form in the original publication [I. Tinoco, J. Chem. Phys. 62, 1006 (1975)]. In addition, some minor errors are corrected and some of the derivations in the original publication are commented. -
Structure determination of uracil-DNA N-glycosylase from Deinococcus radiodurans in complex with DNA
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-10-01) -
Wavelet formulation of the polarizable continuum model. II. Use of piecewise bilinear boundary elements
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-07-27)The simplicity of dielectric continuum models has made them a standard tool in almost any Quantum Chemistry (QC) package. Despite being intuitive from a physical point of view, the actual electrostatic problem at the cavity boundary is challenging: the underlying boundary integral equations depend on singular, long-range operators. The parametrization of the cavity boundary should be molecular- ... -
Complete genome sequence of Vibrio anguillarum strain NB10, a virulent isolate from the Gulf of Bothnia
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-09-02)Vibrio anguillarum causes a fatal hemorrhagic septicemia in marine fish that leads to great economical losses in aquaculture world-wide. Vibrio anguillarum strain NB10 serotype O1 is a Gram-negative, motile, curved rod-shaped bacterium, isolated from a diseased fish on the Swedish coast of the Gulf of Bothnia, and is slightly halophilic. Strain NB10 is a virulent isolate that readily colonizes ... -
Molecular quantum mechanical gradients within the polarizable embedding approach-Application to the internal vibrational Stark shift of acetophenone
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-01-21)We present an implementation of analytical quantum mechanical molecular gradients within the polarizable embedding (PE) model to allow for efficient geometry optimizations and vibrational analysis of molecules embedded in large, geometrically frozen environments. We consider a variational ansatz for the quantum region, covering (multiconfigurational) self-consistent-field and Kohn–Sham density ... -
Linear scaling Coulomb interaction in the multiwavelet basis, a parallel implementation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2014-08-27)We present a parallel and linear scaling implementation of the calculation of the electrostatic potential arising from an arbitrary charge distribution. Our approach is making use of the multi-resolution basis of multiwavelets. The potential is obtained as the direct solution of the Poisson equation in its Green’s function integral form. In the multiwavelet basis, the formally non local ... -
Co-cultivation and transcriptome sequencing of two co-existing fish pathogens Moritella viscosa and Aliivibrio wodanis
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-06-10)Background: Aliivibrio wodanis and Moritella viscosa have often been isolated concurrently from fish with winterulcer disease. Little is known about the interaction between the two bacterial species and how the presence of one bacterial species affects the behaviour of the other. Results: The impact on bacterial growth in co-culture was investigated in vitro, and the presence of A. wodanis has an ... -
Platinum Corroles
(Journal article; Tidsskriftartikkel; Peer reviewed, 2014-06-09)Platinum has been inserted into corroles for the first time and three oxidized PtIV(corrole2)ArAr0 complexes have been structurally characterized. The Soret maxima of these complexes exhibit an unusually strong dependence on the meso-aryl substituents on the corrole, indicating aryl - corrole2 charge transfer character in these transitions. -
The complex structures of isocitrate dehydrogenase from Clostridium thermocellum and Desulfotalea psychrophila support a new active site locking mechanism
(Journal article; Tidsskriftartikkel; Peer reviewed, 2012-07-07)Isocitrate dehydrogenase (IDH) catalyzes the oxidative NAD(P)+ -dependent decarboxylation of isocitrate into a-ketoglutarate and CO2 and is present in organisms spanning the biological range of temperature. We have solved two crystal structures of the thermophilic Clostridium thermocellum IDH (CtIDH), a native open apo CtIDH to 2.35 Å and a quaternary complex of CtIDH with NADP+ , isocitrate and ... -
Intermolecular charge transfer enhances two-photon absorption in yellow fluorescent protein
(Journal article; Tidsskriftartikkel; Peer reviewed, 2014)We present a quantum chemical study of the two-photon absorption (TPA) properties of yellow fluorescent protein (YFP), a mutant of the extensively studied green fluorescent protein. The aromatic chromophore of YFP has a π-stacking interaction with the aromatic ring of a tyrosine residue (Tyr203) in a parallel-displaced structure with a distance of about 3.4 Å. We study the TPA spectrum of the ...
