A fully vectorial technique for scattering and propagation in three-dimensional stratified photonic structures

We present a three-dimensional (3D) technique for computing light scattering and propagation in complex structures formed by scatterers embedded in a stratified background. This approach relies on the Green's tensor associated with the background and requires only the discretization of the scatterers, the entire stratified background being accounted for in the Green's tensor. Further, the boundary conditions at the edges of the computation window and at the different material interfaces in the stratified background are automatically fulfilled. Different examples illustrate the application of the technique to the modeling of photonic integrated circuits: waveguides with protrusions (single element grating) and notches. Subtle effects, like polarization crosstalks in an integrated optics device are also investigated.     

Gold-Catalyzed Facile Synthesis and Crystal Structures of Benzene-/Naphthalene-Based Bispentalenes as Organic Semiconductors

The gold-catalyzed facile synthesis of U-shaped and S-shaped bispentalenes is described from easily available tetra(arylethynyl)-benzenes and -naphthalenes. The optoelectronic and transistor properties were also investigated. The selectivity between the U-shaped and S-shaped bispentalene isomers can be tuned by the bulkiness of the ligand and the substrates. The S-shaped naphthalene-based bispentalene shows a one-dimensional face-to-face packing pattern in solid state and a good hole mobility, indicating that the S-shaped bispentalene core is highly suitable for transistor applications. The gold-catalyzed annulation of tetraynes provides a useful protocol in the synthesis of bispentalenes for organic semiconductors.     

Preparative chromatographic separation of neighboring lanthanides using amines as a pH adjusting additive for producing carrier-free 177Lu

Journal of Radioanalytical and Nuclear Chemistry - This study is a preliminary experiment to examine the effect of amines as additive in eluents for separating neighboring lanthanides (Lu and Yb)...     

peri-Interactions in Naphthalenes, 15: The Concept of Incipient Bipyramidalization in 8-Dimethylaminonaphth-1-yl Silanes and Phosphonium Cations

The concept of a gradual transition from tetracovalent to hypercoordinated silicon and phosphorus in 8-dimethylamino-naphth-1-yl silanes and phosphonium cations is critically examined. Various procedures to quantify partial bipyramidalization fail to indicate incipient hypercoordination. In particular, deviations from tetrahedrality in trialkyl-(8-dimethylamino-naphth-1-yl) silanes and tri(alkyl/phenyl)-(8-dimethylamino-naphth-1-yl) phosphonium cations do not reflect weak N → Si/P bonding. Likewise, the distortions at the P⁺ center in tri(alkyl/phenyl)-(8-diphenylphosphino-naphth-1-yl) phosphonium cations are not indicative of dative P → P⁺ interactions.     

Exogenous Spermidine Alleviates UV-Induced Growth Inhibition of Synechocystis sp. PCC 6803 via Reduction of Hydrogen Peroxide and Malonaldehyde Levels

Effects of exogenously added spermidine (Spd) to UV-treated Synechocystis sp. PCC 6803 cultures on their growth, intracellular pigments, hydrogen peroxide (H₂O₂), malonaldehyde (MDA) contents, and antioxidant enzymes were investigated. Growth inhibition of cells subjected to 1-h UV-A, UV-B, and UV-C irradiation was abolished in culture added with 0.5 mM Spd. Both chlorophyll a and carotenoid contents were decreased under UV radiations in cells grown in BG₁₁ medium. However, the contents of these two pigments were slightly increased under UV radiations in Spd-supplemented cells with the consequence of enhanced oxygen evolution. Intracellular levels of H₂O₂ and MDA generated during 1-h UV irradiation were decreased when the culture medium contained 0.5 mM Spd. The antioxidative enzymes, catalase, and superoxide dismutase had a little or no response towards Spd supplementation under UV irradiation except for some increase in superoxide dismutase activity under UV-C. Total intracellular polyamines were decreased during Spd supplementation under UV stress; however, the cells showed a drastic increase in the amount of Put under this condition. Altogether, exogenous Spd is likely a potential compound that enables Synechocystis cells to cope with UV stress.     

Adsorption of multivalent alkylthiols on Au(111) surface: Insights from DFT

The adsorption of multivalent thiols on gold (111) surface was investigated using density functional theory applying the Perdew–Burke–Ernzerhof functional. Through the comparison of differences in energetics, structure and charge density distribution of a set of monodentate and polydentate thiols, we have described in detail the factors affecting the adsorption energy and the role played by the multivalence, which causes a decreasing of adsorption energy because of both electronic and steric hindrance effects. Finally, the comparison between the adsorption of 1,2‐ and 1,3‐disulfides revealed how the chain length may affect the cleavage of the S? S bond when they adsorb on Au(111) surface. © 2013 Wiley Periodicals, Inc.     

Nonlinear pressure dependence of the interaction potential of dense protein solutions

The influence of pressure on the structure and protein-protein interaction potential of dense protein solutions was studied and analyzed using small-angle x-ray scattering in combination with a liquid state theoretical approach. The structural as well as the interaction parameters of dense lysozyme solutions are affected by pressure in a nonlinear way. The structural properties of water lead to a modification of the protein-protein interactions below 4?kbar, which might have significant consequences for the stability of proteins in extreme natural environments.