Generation of 360-nm ultraviolet light in first-order periodically poled bulk MgO:LiNbO3

Ultraviolet second-harmonic generation in first-order periodically poled MgO:LiNbO3 is presented. Using a high-voltage multipulse application method, we fabricated a first-order nonlinear grating with a period of 1.8 microm and depth of approximately 150 microm over 10-mm interaction length in a 1-mm-thick MgO:LiNbO3 substrate. In a single-pass configuration, continuous-wave 30-mW UV light at 362.5 nm was generated for a fundamental power of 522 mW, corresponding to a normalized conversion efficiency of 11%/W.     

Krafft temperature and enthalpy of solution of<Emphasis Type="Italic"> N</Emphasis>-acyl amino acid surfactants and their racemic modifications: effect of the counter ion

The Krafft temperatures and enthalpies of solution of N-hexadecanoyl alaninate and valinate, and N-tetradecanoyl phenylalaninate were obtained from differential scanning calorimetry. The Krafft temperature of N-acyl amino acid surfactant increased with decreasing size of the counter ion, with some exceptions. The enthalpy of solution was endothermic and increased with decreasing size of the counter ion except for the cases of lithium salt. The results showed that the L-L interaction in the solid state of N-hexadecanoyl amino acid surfactant salt was superior to the D-L interaction for both the alanine and valine systems when the counter ion size increased. However, the D-L interaction was still advantageous for the phenylalanine system with Cs⁺ as a counter ion. Both Fourier transform infrared spectroscopy studies and theoretical calculations suggested that the difference in magnitudes of the interactions between peptide and counter ion was a dominant factor for the chiral effect.     

Sigmasigma* transition in anti,cisoid alternating oligosilanes: clear-cut evidence for suppression of conjugation effect by a cisoid turn

On the basis of the UV absorption spectra of the anti,cisoid alternating oligosilanes, the first experimental clear-cut evidence was presented for the generally accepted idea that the sigma conjugation in polysilanes does not effectively extend through a tetrasilane fragment with a small dihedral angle such as a cisoid turn.     

Development and validation of a high-precision capillary electrophoresis method for main component assay of ragaglitazar

The ability of a developed capillary electrophoresis (CE) method for fast, efficient and reliable main component assay of ragaglitazar [NNC 61-0029/DRF(-)2725] has been demonstrated through documentation of the analytical performance and the results of a successful validation. The fast analysis time of around 1.2 min ensures a high analytical capacity, and the validation results show that the CE method is robust and gives reliable and precise results. The results from the validation of the CE method meet the acceptance criteria that are normally set for other main component assays such as high-performance liquid chromatography assays.     

Wave packet dynamics in a quasi-one-dimensional metal-halogen complex studied by ultrafast time-resolved spectroscopy

An ultrafast optical response is studied in a quasi-one-dimensional halogen-bridged mixed-valence metal complex [Pt(en)(2)] [Pt(en)2I2] (ClO4)(4) with ultrafast time resolution. Wave packet motions both in the ground and self-trapped exciton (STE) states are observed as oscillatory modulations in the time-resolved reflectivity. The wave packet motion on the STE potential surface begins after about 50 fs with respect to the photoexcitation. This delay is attributed to the lattice relaxation from the free exciton state to the STE state.     

Dispersion resulting from phase and amplitude errors in arrayed-waveguide grating multiplexers-demultiplexers

We report dispersion resulting from phase and amplitude errors in arrayed-waveguide grating (AWG) multiplexers-demultiplexers. We measure the phase- and amplitude-error distributions of two different types of AWG and discuss their effects on the dispersion. The results show that the origin of the dispersion in the AWG is the low-order Fourier components of the symmetric phase and the antisymmetric amplitude errors. We also discuss the dependence of the dispersion on the passband shape in the presence of the same fabrication errors.     

DFT studies of ESR parameters for N?O centered radicals,N‐alkoxyaminyl and aminoxyl radicals

Theoretical calculations of ESR parameters for aminoxyl radicals have been widely studied using the density functional theory (DFT) calculations. However, the isomer N‐alkoxyaminyl radicals have been limitedly studied. With the use of experimental data for 46 N‐alkoxyaminyl and 38 aminoxyl radicals, the isotropic ¹⁴N hyperfine coupling constants (a_N) and g‐factors have been theoretically estimated by several DFT calculations. The best calculation scheme of a_N for N‐alkoxyaminyl radicals was PCM/B3LYP/6‐31 + + G(d,p) (R² = 0.9519, MAE = 0.034 mT), and that for aminoxyl radicals was PCM/BHandHLYP/6‐31 + + G(3df,3pd) (R² = 0.9336, MAE = 0.057 mT). For aminoxyl radicals, the solvation models in calculations enhanced the accuracy of reproducibility. In contrast, for N‐alkoxyaminyl radicals the calculations with solvation models provided no improvement. The differences in the best functionals between two types of radicals were thought to come from the contribution ratios of neutral and dipolar canonical structures in resonance forms. The a_N for N‐alkoxyaminyl radicals that were stabilized by small contribution of dipolar canonical structures could be precisely reproduced by B3LYP with only 20% HF exact exchange. In contrast, the a_N for aminoxyl radicals stabilized by large contribution of dipolar canonical structures was well reproduced by BHandHLYP with 50% HF exchange. The best calculation scheme of g‐factors was IEFPCM/B3LYP/6‐31 + G(d,p) (R² = 0.9767, MAE = 0.0001) for not only aminoxyl but also N‐alkoxyaminyl radicals. Copyright © 2011 John Wiley & Sons, Ltd.     

Formation of polyelectrolyte complexes

Interactions between polyelectrolytes carrying opposite charges in aqueous media may lead to either complex coacervation or the formation of interpolymer complexes, depending on the charge density and concentration of polymer components, ionic strength, temperature, and pH. The liquid-liquid phase separation referred to as complex coacervation was thought by Oparin to be an origin of prebiological systems. This article summarizes our recent results on the intermolecular interactions between charged polymer molecules, from the point of view of biological interests.