Measurement of g-factors in 170Yb, 172Yb and 174Yb by transient field interaction at high recoil velocities

A beam of ⁴⁰Ca ions at 168 MeV has been used to Coulomb excite high-spin states in ¹⁶⁹Tm and ^{170, 172, 174}Yb which recoiled through thin polarized iron at ν/c ≈ 3.5%. An enhanced transient field ≈ 6 times larger than the Lindhard-Winther prediction was observed and calibrated against the known g-factors in ¹⁶⁹Tm. Individual g-factors could not be extracted because of strong feeding; nevertheless, deviations from rotational behaviour (constant g-factors) would be detectable. Empirical fits to microscopic calculations of the rotational g-factors below spin 12⁺ suggest that if deviations from the simple rotational formula occur, they should be of the form g(J) = g₀(1 + αJ²). We find the following values in ^{170, 172, 174}Yb: α × 10³ = ?0.5±1.5, +1.0±1.5. The uncertainties are the level at which deviations from rotational behaviour are expected to occur. The results are discussed in terms of Coriolis anti-pairing effects.     

Expanding the Scope of Atropisomeric Monodentate P‐Donor Ligands in Asymmetric Catalysis: Hydrogen‐Transfer Reduction of α,β‐Unsaturated Acid Derivatives by Rhodium/Ph‐binepine Catalysts

A range of α,β‐unsaturated acids and esters have been selectively reduced to the corresponding saturated acid derivatives by hydrogen transfer. As the reducing agent, formic acid was used in the presence of Rh^I complexes formed with the powerful chiral ligand Ph‐binepine ( 1 ), an axially chiral binaphthalene‐type monodentate P‐donor ligand. Very high stereoselectivities (up to 97% ee) were obtained in the case of itaconic acid ( 2a ).     

Reduced Levels of Tissue Inhibitors of Metalloproteinases in UVB‐Irradiated Corneal Epithelium

Tissue inhibitors of metalloproteinases (TIMPs) are the major endogenous regulators of metalloproteinase activity in tissues. TIMPs are able to inhibit activity of all known matrix metalloproteinases (MMPs) and thus participate in controlling extracellular matrix synthesis and degradation. We showed previously elevated expressions of MMPs in the rabbit corneal epithelium upon UVB exposure and suggested that these enzymes might be involved in corneal destruction caused by excessive proteolysis. The aim of this study was to investigate TIMPs in the corneal epithelium after UV irradiation using immunohistochemical and biochemical methods. We found that as compared to control rabbit corneas where relatively high levels of TIMPs were present in the epithelium, repeated irradiation of the cornea with UVB rays (not with UVA rays of similar doses) significantly decreased TIMPs in corneal epithelial cells. The results of this study point to the suggestion that the decrease in TIMPs in the corneal epithelium after UVB irradiation contributes to increased proteolytic activity of MMPs in UVB‐irradiated corneal epithelium found previously.     

Recent trends in enzyme engineering aiming to improve bioelectrocatalysis proceeding with direct electron transfer

Among the known types of electrochemical biosensors, the third generation based on the ability of some enzymes to direct electron transfer (DET) is the most promising one. The enzyme property to DET is depending on its capability to electron transfer from enzymatically reduced built-in native cofactor (flavin mononucleotide, flavin adenine dinucleotide, pyrroloquinoline quinone, or heme) to a conductive surface directly for single cofactor enzymes or through a native structural electron acceptor (heme or copper-containing prosthetic groups) for multicofactor enzymes. Thus, there are two possibilities to use such type enzymes: to find a natural source of the enzyme with these properties; or to construct the recombinant chimeric analogs using the gene-engineering techniques. The modern molecular genetics opens the possibility to be independent of million-year natural evolution and engineer the specific enzymes for scientific and technological needs. This brief review is focused mostly on the recent publications on application of DET-capable engineered enzymes for the third-generation electrochemical biosensors.     

Prediction of iron K-edge absorption spectra using time-dependent density functional theory

Iron K-edge X-ray absorption pre-edge features have been calculated using a time-dependent density functional approach. The influence of functional, solvation, and relativistic effects on the calculated energies and intensities has been examined by correlation of the calculated parameters to experimental data on a series of 10 iron model complexes, which span a range of high-spin and low-spin ferrous and ferric complexes in O(h) to T(d) geometries. Both quadrupole and dipole contributions to the spectra have been calculated. We find that good agreement between theory and experiment is obtained by using the BP86 functional with the CP(PPP) basis set on the Fe and TZVP one of the remaining atoms. Inclusion of solvation yields a small improvement in the calculated energies. However, the inclusion of scalar relativistic effects did not yield any improved correlation with experiment. The use of these methods to uniquely assign individual spectral transitions and to examine experimental contributions to backbonding is discussed.     

Properties of the singular, inverse and generalized inverse partitioned Wishart distributions

In this paper we discuss the distributions and independency properties of several generalizations of the Wishart distribution. First, an analog to Muirhead [R.J. Muirhead, Aspects of Multivariate Statistical Theory, Wiley, New York, 1982] Theorem 3.2.10 for the partitioned matrix is established in the case of arbitrary partitioning for singular and inverse Wishart distributions. Second, the density of is derived in the case of singular, non-central singular, inverse and generalized inverse Wishart distributions. The importance of the derived results is illustrated with an example from portfolio theory.     

Imaging and sizing of diamond nanoparticles

Typical disturbances of biological environment such as background scatter and refractive index variations have little effect on the size-dependent scattering property of highly refractive nanocrystals, which are potentially attractive optical labels. We report on what is to our knowledge the first investigation of these scattering optical labels, and their sizing, in particular, by imaging at subvideo frame rates and analyzing samples of diamond nanocrystals deposited on a glass substrate in air and in a matrix of weakly scattering polymer. The brightness of a diffraction-limited spot appears to serve as a reliable measure of the particle size in the Rayleigh scattering limit.     

On topological Clifford semigroups embeddable into products of cones over topological groups

In this paper we give characterizations of topological Clifford semigroups which are embeddable into Tychonoff products of topological semilattices and cones over topological groups. Also we characterize topological Clifford semigroups which embed into compact topological Clifford semigroups.     

Moderately deformed bands in the continuum of144Gd

The lifetimes of the gamma-ray continuum in¹⁴⁴Gd were measured up to spin ～ 50? via the DSAM technique following the⁷⁴Ge(⁷²Ge, 2n) reaction at 270 MeV beam energy. The average Doppler Shift of theE2 bump corresponds mostly to a structure with a deformation (β～0.2–0.3), consistent with the triaxial structure predicted to lie close to the yrast line at spins 30–50? in this nucleus.