Berry pseudorotation mechanism for the interpretation of the 19F NMR spectrum in PF5 by ab initio molecular dynamics simulations.

For the first time, theoretical evidence that confirms the importance of the Berry pseudorotation process in the interpretation of the 19F NMR spectrum of phosphorus pentafluoride (PF5) is presented. Ab initio molecular dynamics simulations have been performed to generate a large number of configurations used for NMR parameter computations at the density functional theory level. Two different temperatures were set to highlight the effect of pseudorotation process on the NMR spectrum.

Ab initio dynamic study of the reaction of Cl2LaR (R=H, CH3) with H2.

In this paper, a comparison between "static" and "dynamic" determination of the thermodynamic (DeltarF degrees) and kinetic data (DeltarF#) for the reaction of Cl2LaR (R=H, CH3) and H2 is given. A difference is obtained in the case of the reaction between Cl2LaH and H2 and can be attributed to a failure of the "static" approach based on the harmonic approximation. The influence of the zero point energy correction is also analyzed but does not explain the 30% difference between the two calculated activation energies.

Molecular characterization and mapping of ALMT1, the aluminium-tolerance gene of bread wheat (Triticum aestivum L.).

The major aluminum (Al) tolerance gene in wheat ALMT1 confers. An Al-activated efflux of malate from root apices. We determined the genomic structure of the ALMT1 gene and found it consists of 6 exons interrupted by 5 introns.

On the accuracy of one-component pseudopotential spin-orbit calculations.

Improvements on current one-component extraction procedures of spin-orbit pseudopotentials are investigated for high accuracy computation of spin-orbit coupling energies. By means of the perturbation-theory formalism we first show that spin-orbit pseudopotentials, extracted at the one-component self-consistent-field level from a reference all-electron Dirac-Coulomb or Dirac-Coulomb-Breit calculation, include valence spin-orbit polarization and relaxation effects. As a consequence the use of these pseudopotentials in uncontracted spin-orbit configuration interaction (CI) with singles from the reference ground-state configuration gives rise to double counting of these spin-orbit effects.

Glutathione S-transferase and aluminum toxicity in maize.

Aluminum (Al) toxicity induces changes in the expression of several genes, some of which are involved in plant responses to oxidative stress. Using mRNA differential display, we identified a maize Al-inducible cDNA encoding a glutathione S-transferase (GST). The gene was named GST27.

Atomic spin-orbit pseudopotential definition and its relation to the different relativistic approximations.

A critical analysis of usual shape-consistent spin-orbit pseudopotential extraction procedures is presented, considering the basic requirements of the atomic pseudopotentials. It is based on a perturbative analysis of both reference all-electron Dirac-Coulomb and pseudopotential calculations by means of the formalism developed by Lindgren and Morrisson. In the light of this analysis, we propose a new hybrid extraction of spin-orbit pseudopotentials, taking advantage of both shape-consistent and energy-consistent procedures.

Hydrogen for fluorine exchange in CH4-xFx by monomeric [1,2,4-(Me3C)3C5H2]2CeH: experimental and computational studies.

The monomeric metallocenecerium hydride, Cp'(2)CeH (Cp' = 1,2,4-tri-tert-butylcyclopentadienyl), reacts instantaneously with CH(3)F, but slower with CH(2)F(2), to give Cp'(2)CeF and CH(4) in each case, a net H for F exchange reaction. The hydride reacts very slowly with CHF(3), and not at all with CF(4), to give Cp'(2)CeF, H(2), and 1,2,4- and 1,3,5-tri-tert-butylbenzene. The substituted benzenes are postulated to result from trapping of a fluorocarbene fragment derived by alpha-fluoride abstraction from Cp'(2)CeCF(3).

Cytokine gene polymorphisms in patch-stage mycosis fungoides.

Cytokine production is under genetic control and certain allelic variants of cytokine genes are associated with lower or higher cytokine production in vitro and in vivo. The general concept is that a shift from a Th1 to a Th2 cytokine profile accompanies disease progression from patch-stage mycosis fungoides to tumour stage, although the results of the studies carried out have not been entirely conclusive. We aimed to investigate whether certain cytokine polymorphisms might represent a risk factor for developing patch-stage mycosis fungoides.

Familial mycosis fungoides: report of 6 kindreds and a study of the HLA system.

Background: The familial occurrence of mycosis fungoides (MF) has been reported only in 8 families. Recently, the HLA class II alleles DRB1* 11 and DQB1* 03 have been found to be significantly increased for patients with sporadic MF, suggesting a possible immunogenetic basis for the pathogenesis of this malignancy.

Objective: We sought to detect familial occurrences of MF, to describe familial features, and to investigate the possible association or linkage with the HLA system in such cases.

Hydrogen for fluorine exchange in C6F6 and C6F5H by monomeric [1,3,4-(Me3C)3C5H2]2CeH: experimental and computational studies.

The net reaction of monomeric Cp'(2)CeH [Cp' = 1,3,4-(Me(3)C)(3)(C(5)H(2))] in C(6)D(6) with C(6)F(6) is Cp'(2)CeF, H(2), and tetrafluorobenzyne. The pentafluorophenylmetallocene, Cp'(2)Ce(C(6)F(5)), is formed as an intermediate that decomposes slowly to Cp'(2)CeF and C(6)F(4) (tetrafluorobenzyne), and the latter is trapped by the solvent C(6)D(6) as a [2+4] cycloadduct. In C(6)F(5)H, the final products are also Cp'(2)CeF and H(2), which are formed from the intermediates Cp'(2)Ce(C(6)F(5)) and Cp'(2)Ce(2,3,5,6-C(6)F(4)H) and from an unidentified metallocene of cerium and the [2+4] cycloadducts of tetra- and trifluorobenzyne with C(6)D(6).

An analysis of core effects on shape-consistent pseudopotentials.

Large core (seven-valence electrons) shape-consistent averaged relativistic pseudopotentials (AREP) including core effects have been derived for the halogen series (Cl,Br,I,At). The influence of core effects on the spin-orbit splitting of the halogen and alkali atoms is clearly demonstrated within an all-electron four-component atomic reference calculation by means of a perturbation analysis. In particular, it is shown that AREPs extracted at the Dirac-Coulomb-Fock level, which already include spin-orbit polarization effects, give excellent results for atomic spectroscopy and equilibrium distances of halogen dimers.

Quantum chemistry-based interpretations on the lowest triplet state of luminescent lanthanides complexes. Part 1. Relation between the triplet state energy of hydroxamate complexes and their luminescence properties.

In this paper, we evaluate the potential use of theoretical calculations to obtain an energy scale of the lowest ligand-centred triplet excited state in luminescent terbium(III) complexes. In these complexes, non-radiative deactivation of the terbium emitting state via a back-energy transfer process (T1<--Tb(5D4)) is a common quenching process. Consequently the prediction of the energy gap between these two excited states should be useful for programming highly luminescent Tb(III) systems.

An open trial of climatotherapy at the Dead Sea for patch-stage mycosis fungoides.

Background: Climatotherapy at the Dead Sea (CDS) is a well-established therapeutic modality for moderate to severe psoriasis vulgaris, resulting in sustained remissions. It has also been found to be effective for atopic dermatitis, another T-cell-mediated dermatosis.

Objective: We sought to prospectively evaluate the efficacy of CDS in patch-stage mycosis fungoides.

Some structural and electronic properties of MX3 (M = Ln, Sc, Y, Ti+, Zr+, Hf+; X = H, Me, Hal, NH2) from DFT calculations.

The geometry of trivalent homoleptic d0 MX3 (X = H, Me, Hal, NH2) complexes for the entire lanthanide family, neutral group 3 and cationic group 4 metal center complexes have been studied with DFT(B3PW91) calculations. The geometrical parameters are in good agreement with the available experimental data. The degree of pyramidalization of the metal is discussed.

Climatotherapy at the Dead Sea is a remittive therapy for psoriasis: combined effects on epidermal and immunologic activation.

Background: The beneficial effect of climatotherapy at the Dead Sea (CDS) for psoriasis has been established clinically but there is a striking lack of studies assessing its in vivo effect at the molecular and cellular levels.

Objective: We sought to study the response of activated immunologic cells and keratinocytes in psoriatic lesions to CDS.

Methods: A total of 27 patients with chronic, stable, plaque-type psoriasis treated with CDS for 28 consecutive days were evaluated with the Psoriasis Area and Severity Index score and quantitative histologic measures.

Using effective group potential methodology for predicting organometallic complex properties.

Using the Effective Group Potentials (EGP) method, optimal geometries, harmonic vibrational frequencies, and relative energies of different sets of metal complexes are calculated. All of the systems under consideration contain the cyclopentadienyl (Cp) ligand. They are as follows: (i).

Mono-, di-, and Ttianionic beta-diketiminato ligands: a computational study and the synthesis and structure of [(YbL)(3)(THF)], L = [[N(SiMe(3))C(Ph)](2)CH].

A trinuclear Yb beta-diketiminato cluster [(YbL)3(THF)] (1) (L = {N(SiMe3)C(Ph)}2CH), containing L-1 and L-3 as well as Yb(II) and Yb(III) centers, was obtained by treatment of [YbL2] with Yb-naphthalene and was characterized by X-ray crystallography. The electron distribution in 1 and the Yb(II)/L-2 complex [Yb{(mu-L)Li(THF)}2] (2) was analyzed by DFT and ONIOM (QM/MM) calculations.

Word and picture processing in children: an event-related potential study.

In an investigation of the N400 component, event-related potentials (ERPs) elicited by 4 types of word stimuli (real words, pseudowords, random letter strings, and false fonts) and 3 types of picture stimuli (real pictures, pseudopictures, and picture parts) presented in separate lists were recorded from 10- and 11-year-old children. All types of word stimuli elicited an anteriorly distributed negativity peaking at about 400 msec (antN400). Words and pseudowords elicited similar ERPs, whereas ERPs to letter strings differed from those to both pseudowords and false fonts.

Cerium masquerading as a group 4 element: synthesis, structure and computational characterisation of [CeCl(N(SiMe3)2)3].

Oxidation of the three-coordinate cerium amide [Ce(N-(SiMe3)2)3] with TeCl4 in toluene solution yields purple, diamagnetic [CeCl(N(SiMe3)2)3], whose structure has been examined by X-ray crystallographic and computational methods.

A DFT study of SiH(4) activation by Cp(2)LnH.

A theoretical study of SiH(4) activation by Cp(2)LnH complexes for the entire series of lanthanides has been carried out at the DFT-B3PW91 level of theory. The reaction paths corresponding to H/H exchange and silylation, formation of Cp(2)Ln(SiH(3)), have been computed. They both occur via a single-step sigma-bond metathesis mechanism.

Semantic monitoring of words with emotional connotation during fMRI: contribution of anterior left frontal cortex.

Previous studies showed that cortex in the anterior portions of the left frontal and temporal lobes participates in generating words with emotional connotations and processing pictures with emotional content. If these cortices process the semantic attribute of emotional connotation, they should be active whenever processing emotional connotation, without respect to modality of input or mode of output. Thus, we hypothesized that they would activate during monitoring of words with emotional connotations.

Are the carbon monoxide complexes of Cp(2)M (M = Ca, Eu, or Yb) carbon or oxygen bonded? An answer from DFT calculations.

DFT calculations have been performed on the CO adducts of the bivalent lanthanides, Cp(2)M(CO)(x), where M is Eu or Yb and x is 1 or 2, the alkaline earth metallocene Cp(2)Ca(CO), and the methylisocyanide adducts of Yb. The calculated nu(CO) values are in agreement with experiment for Cp(2)M(CO) when M is Ca or Eu, but in striking disagreement when the CO is bound to the metal by way of the carbon atom in CO in the case of Yb. The calculated nu(CO) values for M = Yb are brought into agreement with experiment when the CO is allowed to bond to Cp(2)Yb by way of the oxygen atom.

DFT study of H--H activation by Cp(2) LnH d(0) complexes.

The energy required to activate the H--H bond in the entire series of Cp(2)LnH complexes has been calculated by DFT (B3PW91) methods. The activation energies have been calculated to vary from 0.5 to 8.