Inorganic pollutants in the indoor environment of the Moravian Library: assessment of Cd, Pb, Cu, and Zn in total suspended particles and dust using HR-CS GF-AAS.

In this study, the occurrence of lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn) in the environment of the Moravian Library in Brno, the second largest library in Czechia, was in focus. The materials of interest were airborne particles, dust originating from books, and also book pages. Total suspended particles (TSP) were sampled in different areas of the library, including the reading room, the book depository, and an external book warehouse. Samples of dusts were obtained from the book-cleaning system, and, moreover, some pages taken from old books were also analyzed. Samples were microwave-digested and analyzed using graphite furnace high-resolution continuum source AAS (HR-CS GF-AAS). During the analysis, possibilities of the signal intensity modulation of the HR-CS technique were demonstrated and employed in order to determine Zn, an element which is rarely determined by GF-AAS. The median TSP concentrations (in ng/m3) were as follows: Pb, 4.4; Cd, 0.07; Cu, 2.6; and Zn, 20.9. Such concentrations are safely below allowed limits. Contents of Pb determined in dust samples and book pages were slightly higher (up to 707 and 38 mg/kg, respectively) than the usually reported values. However, none of these results indicate a potential risk to library staff or readers.

Stereochemistry of Vanadium Peroxido Complexes: The Case of the Quinoline-2-carboxylato Ligand.

A new mononuclear vanadium peroxido complex [VO(O2)(phen)(quin)]·H2O (1) exhibiting an unprecedented isomerism of its ligands was isolated from a two-component water-acetonitrile solvent system. DFT computations aimed at inspecting the stability of all possible isomers of complexes [VO(O2)(L1)(L2)], where L1 and L2 are NN+ON, OO+ON, NN+OO, and ON+ON donor atom set ligands, suggested that every complex characterized so far was the one preferred thermodynamically. However, the particular case of complex [VO(O2)(phen)(quin)] reported herein poses a notable exception to this rule, as this complex yielded single crystals of the isomer with total energy above the anticipated isomer, although both of these isomers could be observed concurrently in solution and also in the solid state. 51V NMR spectroscopy suggested these isomers to be present both in the crystallization solution and in the acetonitrile solution of 1. The coexistence of two isomers is a consequence of their small computed energy difference of 2.68 kJ mol-1, while the preferential crystallization favoring the unexpected isomer is likely to be triggered by solvent effects and the effects of different solubility and/or crystal packing. The coordination geometry of the unusual isomer also manifests itself in FT-IR and Raman spectra, which were corroborated with DFT computations targeted at band assignments.

Doubly Occupied Pair Coupled Cluster F12 Approach.

Inspired by reports of the good performance of the doubly occupied pair coupled cluster (pCCD) theory in describing static electron correlation, we have introduced and implemented a variant thereof that includes single excitations and explicitly treats the dynamic electron correlation using the F12 methodology (pCCSD-F12). This drastically reduces the computation scaling with respect to the standard method using the full double-excitation operator (CCSD-F12). Slater-type geminals as a correlation factor, together with fixed cusp conditions, were used, which is known as the SP-ansatz. For sample model systems, we have investigated the performance of reference states constructed from either canonical or localized molecular orbitals. Finaly, the employment of Brueckner orbitals has been tested, which causes the single excitations to naturally vanish from the wave function expansion (B-pCCD-F12). Our test systems include different-sized rings of hydrogen atoms and dissociation curves for small molecules such as HF, N2, and CO2; and comparison with CCSD-F12 is presented for a series of reaction enthalpies.

Adolescent body image: results of Czech ELSPAC study.

OBJECTIVES: The study examined appearance and body satisfaction in adolescents. For these purposes, data from the European Longitudinal Study of Pregnancy and Childhood in the Czech Republic were used. METHODS: The data were collected in 2010 and the sample comprised 3,105 18-year-old respondents. RESULTS: The research found that the respondents who wished to reduce their weight were mostly women with BMI in the normal range. Based on the body cathexis scale, we found that women compared to men are more critical of stomach, hips, buttocks, and thighs, as well as overall weight and figure. The results showed that criticism of their weight from their immediate environment is unpleasant to both female and male adolescents to such an extent that it makes them try to reduce it. However, it is clear that girls are altogether less satisfied with their bodies than boys. CONCLUSION: For both genders, body dissatisfaction is most likely enhanced by critical comments from peers and parents about appearance, body weight etc.

Changes in BMI in hospitalized patients during treatment with antipsychotics, depending on gender and other factors.

OBJECTIVE: To investigate the differences in body mass index (BMI) changes between men and women during hospitalization. METHODS: The retrospective study monitored demographic and clinical data of 462 schizophrenic patients hospitalized 737 times between 2006 and 2011. BMI analysis was performed on patients on antipsychotic medication hospitalized longer than four days. RESULTS: Patients with an initial BMI < 25 gained more weight than patients with a BMI > 25 (3.94% vs. 0.23%, men 4.02% vs. 0.69%, women 3.79% vs. -0.52%, always p < 0.001). Greater BMI gains were reported during the first hospitalization than during subsequent ones (3.94% vs. 1.66%, men 3.97% vs. 1.98%, women 3.88% vs. 1.18%, always p < 0.001). The comparison between men and women showed a higher increase in BMI in men 2.36% vs. 1.54%, p = 0.022. Men also gained significantly more weight than women on polytherapy (+2.55% vs. +1.37%) and during subsequent hospitalizations (1.98% vs. 1.18%). For treatment with various atypical antipsychotics (AP), no significant differences were found in weight changes between men and women; during treatment using a combination of multi-receptor AP and metabolically neutral aripiprazole, a significant increase of BMI occurred in men, but not in women (p = 0.018). CONCLUSIONS: Men appear to be more prone to weight gain than women.

Stereospecificity in vanadium Schiff base complexes: Formation, crystallization and epimerization processes.

The structures of two stereoisomers of the chiral anion [VO2(N-salicylidene-isoleucinato)](-) possessing three centers of chirality, the vanadium atom (configuration A/C) and the isoleucine moiety (configuration R/S on alpha and beta carbons), are presented. The absolute configuration of all available stereosiomers, CSS, ARR, CSR and ARS, was determined by electronic circular dichroism (ECD), which allows distinguishing between diastereomers, and by vibrational circular dichroism (VCD) capable of differentiating between all four stereoisomers. The comparison of experimental VCD and infrared (IR) spectra with simulated spectra for band assignment revealed the IR spectra of the diastereomers differing significantly in the CH stretching region of the aromatic part in the molecule. Crystallization from binary systems composed of equal ratio of two stereoisomers of isoleucine, unveiled the lower solubility of CSS and ARR stereoisomers, while a longer crystallization time of the CSR and ARS stereoisomers allowed proceeding the vanadium-catalyzed epimerization, leading to the subsequent presence of the CSS and ARR stereoisomers in the product obtained.

Vanadium-controlled crystallization of stereoisomers of NBu4[VO2(N-salicylidene-isoleucinato)] through epimerization.

Reported herein is a simple synthetic and crystallization procedure for sequential isolation of two stereoisomers of isoleucine-derived vanadium(V) complexes from a racemic mixture with three stereogenic centers and therefore eight hypothetical species. The products of this crystallization were characterized by electronic and vibrational circular dichroism, NMR spectroscopy, and polarimetry to compare the chiroptic properties of the enantiomerically pure analogues prepared from L-isoleucine and D-allo-isoleucine. NMR studies pointed to the yet unobserved phenomenon of vanadium-catalyzed epimerization of isoleucine.

Acceleration of self-consistent-field convergence by combining conventional diagonalization and a diagonalization-free procedure.

A new scheme that combines conventional matrix diagonalization with the recently proposed diagonalization-free algorithm has been developed to obtain the density matrix for the next self-consistent-field iteration from the Fock matrix of the current iteration. In this manner, the advantages of the two methods are combined. The more rapid convergence of the diagonalization-free algorithm for density matrices rather close to self consistence and the more robust convergence of the conventional matrix diagonalization further away from self-consistence. The scheme has been implemented in the one- and two-component self-consistent-field procedures in the program system TURBOMOLE. The number of iterations is typically reduced by about 10%, but savings are usually much larger for slowly converging cases.

Solving the Independent-Particle Model via Nonunitary Transformation Based on Variational Coupled Cluster Singles.

We propose an alternative new approach to obtain the Slater determinant ground state solution within an independent-particle approximation using the exponential ansatz for the wave function (Thouless theorem) and exact treatment in terms of variational coupled cluster singles. Although the resulting nonlinear equations formally represent nonterminating expansions, these can be reformulated to finite expansions in terms of the density matrix correction. The latter can be exactly calculated using a very simple recurrence relation within the occupied-occupied block, while the complementary occupied-virtual and virtual-virtual blocks are related and trivially obtained by subsequent matrix multiplications involving the amplitudes of the single-excitation operator. The density matrix is naturally idempotent in any step of the iterative procedure. Blocks of the density matrix are without any further change, apart from the sign, used in the orbital transformation matrix. The latter is not a unitary one, hence leading to nonorthogonal and unnormalized molecular orbitals. These are, however, biorthogonal and can be easily orthonormalized per blocks, if needed in the post-SCF calculations. Formulation is diagonalization free, and the implementation can be easily parallelized. Finally, the formulation provides a challenging way to the solution with "a priori" localized orbitals, a way toward a linear scaling algorithm.

On the variational computation of a large number of vibrational energy levels and wave functions for medium-sized molecules.

In a recent publication [J. Chem. Phys. 127, 084102 (2007)], the nearly variational DEWE approach (DEWE denotes Discrete variable representation of the Watson Hamiltonian using the Eckart frame and an Exact inclusion of a potential energy surface expressed in arbitrarily chosen coordinates) was developed to compute a large number of (ro)vibrational eigenpairs for medium-sized semirigid molecules having a single well-defined minimum. In this publication, memory, CPU, and hard disk usage requirements of DEWE, and thus of any DEWE-type approach, are carefully considered, analyzed, and optimized. Particular attention is paid to the sparse matrix-vector multiplication, the most expensive part of the computation, and to rate-determining steps in the iterative Lanczos eigensolver, including spectral transformation, reorthogonalization, and restart of the iteration. Algorithmic improvements are discussed in considerable detail. Numerical results are presented for the vibrational band origins of the (12)CH(4) and (12)CH(2)D(2) isotopologues of the methane molecule. The largest matrix handled on a personal computer during these computations is of the size of (4x10(8))x(4x10(8)). The best strategy for determining vibrational eigenpairs depends largely on the actual details of the required computation. Nevertheless, for a usual scenario requiring a large number of the lowest eigenpairs of the Hamiltonian matrix the combination of the thick-restart Lanczos method, shift-fold filtering, and periodic reorthogonalization appears to result in the computationally most feasible approach.

Explicitly correlated coupled cluster F12 theory with single and double excitations.

Full explicitly correlated F12 coupled cluster theory with single and double excitations and with Slater-type geminal as a correlation factor is introduced and implemented within the standard approximation. The variant "C" that does not require integrals over the commutator between the kinetic operator and the correlation factor has been used. All the necessary integrals are analytically calculated. With variant C also, first results are reported for the correlation factor being the interelectronic distance coordinate, i.e., for original R12 method. Calculations have been performed for a set of eight molecules including CH(2)((1)A(1)), CH(4), NH(3), H(2)O, HF, CO, N(2), and F(2), as well as for the constituting atoms. Atomization energies are reported too.

Second order explicitly correlated R12 theory revisited: a second quantization framework for treatment of the operators' partitionings.

Second order R12 theory is presented and derived alternatively using the second quantized hole-particle formalism. We have shown that in order to ensure the strong orthogonality between the R12 and the conventional part of the wave function, the explicit use of projection operators can be easily avoided by an appropriate partitioning of the involved operators to parts which are fully describable within the computational orbital basis and complementary parts that involve imaginary orbitals from the complete orbital basis. Various Hamiltonian splittings are discussed and computationally investigated for a set of nine molecules and their atomization energies. If no generalized Brillouin condition is assumed, with all relevant partitionings the one-particle contribution arising in the explicitly correlated part of the first order wave function has to be considered and has a significant role when smaller atomic orbital basis sets are used. The most appropriate Hamiltonian splitting results if one follows the conventional perturbation theory for a general non-Hartree-Fock reference. Then, no couplings between the R12 part and the conventional part arise within the first order wave function. The computationally most favorable splitting when the whole complementary part of the Hamiltonian is treated as a perturbation fails badly. These conclusions also apply to MP2-F12 approaches with different correlation factors.