Temperature dependent phonon modes and ionicity of LiGaO2 single crystal

This paper reports that polarized far-infrared reflectivity measurements have been done on LiGaO2 single crystal along two crystalline taxes at different temperatures. The temperature dependent frequencies of the longitudinal and transverse optical phonon have been obtained from the real part of optical conductivity and the loss function respectively. A small Drude component is observed at frequency below 300 cm^-1 which could arise from Li ions or oxygen deficiencies. The ionicity of LiGaO2 has been studied from the analysis of the Born effective charge of different ions.     

THE DUAL ABSORPTIVE MODE AND πP ELASTIC SCATTERING REVISITED

Using the Regge pole phase rule for contrilbutions to both amplitudes the DAM is applied to ^πp elastic scattering in the p_lab≥10 GeV/c and |t|≤0.8(GeV/c)² region. It is found that the DAM has a mixed success in describing ^πp scattering. The p contribution to both amplitudes is in accord with the DAM while the f-non-flip contribution does not have a peripheral zero.The Pomeron imaginary part is in accord with the DAM with a non-negligible Pomeron phase so that the DAM approximation Rep=O is unsatisfactory. There is also a Pomeron-flip contribution contrary to the expectation of the model. The O-flip contribution is taken into account and a small f-flip contribution i s also required.     

Multichannel vector sum phase shifter

A novel multichannel vector sum phase shifter that is suitable for phased array antenna applications is demonstrated. Each channel is implemented using a distinct optical wavelength. Selective control of each channel is performed using an acousto-optic polarization coupler. The concept is successfully demonstrated for two individually controlled channels. For each channel, a continuously variable frequency linear phase shift is demonstrated between DC and 7 GHz, with the phasing range exceeding 100 degrees.     

Resonance Assisted Chalcogen Bonding as a New Synthon in the Design of Dyes

Intramolecular chalcogen bonding in arylhydrazones of sulfamethizole is strengthened by conjugation in the π-system of a noncovalent five-membered ring. The S⋅⋅⋅O distance in the sulfamethizole moiety of these compounds ranges from 2.698(3) to 2.806(15) Å, which indicates its strong dependence on the attached arylhydrazone fragments. Information on the nature of the intramolecular chalcogen bond was afforded by DFT calculations.     

Photocatalytic Performance of H6P2W18O62/TiO2 Nanocomposite Encapsulated into Beta Zeolite under UV Irradiation in the Degradation of Methyl Orange

In this work, neat and supported H₆P₂W₁₈O₆₂ into nanocage of β‐zeolite were synthesized. However, H₆P₂W₁₈O₆₂ into nanocage of β‐zeolite was synthesized via template synthesis method. In addition, TiO₂ was supported on H₆P₂W₁₈O₆₂/β zeolite by impregnation method. The obtained materials were characterized by XRD, FT‐IR, UV‐Vis, FESEM and EDS techniques. Also, W and Ti contents of the catalyst were determined by ICP and EDS technique. The results reveal that the photocatalyst performance depends on catalyst loading, pH effect, and methyl orange concentration. Photocatalytic degradation of methyl orange follows a pseudo‐first order kinetic. The chemical oxygen demand (COD) experimental proved mineralization of methyl orange. Another reason for degradation and mineralization of methyl orange is the absence of hydrazine at the end of reaction which is one of the photodecolorization products. The plausible mechanism for photodegradation of MO was proposed.     

Influence of substitution on the strength and nature of CH···N hydrogen bond in XCCH···NH3 complexes

The effect of substitution on the strength and nature of CH···N hydrogen bond in XCCH···NH₃ (X = F, Cl, Br, OH, H, Me) and NCH···NH₃ complexes were investigated by quantum chemical calculations. Ab initio calculations were performed using MP2 method with a wide range of basis sets. With tacking into account the BSSE and ZPVE, the values of BEs decrease. Replacement of the nonparticipatory hydrogen atom of HCCH by the electronegative atoms (F, Cl, and Br), lead to the BEs increases. The BE corresponding to the replacement of the nonparticipatory hydrogen atom of HCCH by the OH and CH₃ groups decreases. A far greater enhancement of the interaction energy arises from replacement of HCCH by the more acidic HCN. The natural bond orbital analysis and the Bader's quantum theory of atoms in molecules were also used to elucidate the interaction characteristics of these complexes. The electrostatic nature of H‐bond interactions is predicted from QTAIM analysis. In addition, the relationship between the isotropic and anisotropic chemical shifts of the bridging hydrogen and binding energy of complexes as well as electron density at N···H BCPs were investigated. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Multiresidue determination of pesticides from aquatic media using polyaniline nanowires network as highly efficient sorbent for microextraction in packed syringe

A simple, rapid and sensitive method based on microextraction in packed syringe (MEPS), in combination with gas chromatography–mass spectrometry (GC–MS) was developed. Polyaniline (PANI) nanowires network was synthesized and used as sorbent of MEPS for the multiresidue determination of selected analytes from triazine, organochlrorine and organophosphorous pesticides in aqueous samples. The PANI nanowires network was prepared using soft template technique and its characterization was studied by scanning electron microscopy (SEM). The presence of micelles in this methodology showed to be an important parameter in shaping the growing polymer. Hexadecyltrimethylammonium bromide (HTAB) was used as structure directing agent in PANI preparation procedure and this was led to the formation of nanowires with diameters ranging from 35 nm to 45 nm. The synthesized PANI nanowires network showed higher extraction capability in comparison with the bulk PANI. Important parameters influencing the extraction and desorption processes including desorption solvent, elution volume, draw–eject cycles of sample, draw–eject mode, pH effect and amount of sorbent were optimized. Limits of detection were in the range of 0.07–0.3 ng mL⁻¹ using time scheduled selected ion monitoring (SIM) mode. The linearity of method was in the range from 0.5–200 ng mL⁻¹ to 0.2–1000 ng mL⁻¹. The method precision (RSD %) with three replicates were in the range of 5.3–18.4% at the concentration level of 5 ng mL⁻¹. The developed method was successfully applied to the Zayandeh-rood river water samples and the matrix factor obtained for the spiked real water samples were in the range of 0.79–0.94.     

A mechanistic insight into caspase-7 inhibition by BIR1-2 domains of XIAP and cIAP1

Previous studies failed to demonstrate any role for the BIR1 domain of the inhibitor of apoptosis proteins (IAPs) in inhibition of executioner caspases. In this study, XIAP-BIR1-2 and c-IAP1-BIR1-2 domains have been used to investigate the role of BIR1 in the inhibition of caspase-7. Kinetic analysis confirmed that caspase-7 was inhibited in an uncompetitive manner at lower concentrations of XIAP-BIR1-2, whereas the inhibition was switched to the mixed type mode at higher concentrations of the inhibitor. In contrast, cIAP1-BIR1-2 inhibited caspase-7 in a mixed type mode at all examined concentrations. These data suggest that the presence of BIR1 is essential for inhibition of caspase-7 by cIAP1. Far-UV CD and fluorescence spectroscopy experiments showed that despite similar secondary structures, XIAP-BIR1-2 and cIAP1-BIR1-2 have different biophysical properties. BIR1-2 domain of XIAP was found to be more flexible than cIAP1, which may be the reason behind differences in their kinetic properties.