Oxidative Cleavage of Ketoximes with Iodosobenzene Diacetate

Hypervalent iodine oxidation of ketoximes (1) using iodosobenzene diacetate leads to cleavage of 1 with the formation of corresponding ketones (2) under neutral conditions in good yields. The scope and limitations of the reaction are discussed as well as the mechanism.     

Effect of cryopreservation protocols on the phenotypic stability of yeast

Eight cryopreservation protocols were assessed for their effects on the viability and phenotypic stability of the yeast Saccharomyces cerevisiae during a five-year study. It is found that viability and phenotypic features have remained largely unchanged when the yeast was preserved in glycerol, dimethyl sulphoxide, or sucrose at -80 degrees C or in liquid nitrogen. When sorbitol was used as a cryoprotectant, yeast cells frozen and stored at -80 degrees C manifested great decreases in viability after six months in storage and concomitantly large fluctuations in the rate of the trpl auxotrophic reversion. This phenotypic reversion was stable passage after passage. Such a degree of phenotypic fluctuations, however, was not observed for yeast cells preserved in the same sorbitol solution that went through a controlled freezing program and were subsequently stored in liquid nitrogen. These results indicate that some combinations of cryoprotective agent, freezing program, and storage temperature disturb biomaterials more profoundly during cryopreservation and imply a genetic basis of this phenotypic change.     

Symmetries, vibrational instabilities, and routes to stable structures of clusters of Al, Sn, and As

We investigate the stability of small clusters using density functional theory to compute the total energy, forces, and vibrational frequencies using linear response. We exhibit an efficient and computationally low-cost route to finding stable structures, by starting with high-symmetry structures and distorting them according to their unstable modes. We illustrate this by application to 4-, 6-, and 13-atom clusters of Al, Sn, and As. This technique also naturally elucidates the origins of stability of the lower symmetry structures, which is variously due to the linear or pseudo Jahn-Teller effect, combined with a lowering of various contributions to the total energy. We show that the situation is more complex than has generally been appreciated.     

Novel LC‐ ESI‐MS/MS method for desvenlafaxine estimation human plasma: application to pharmacokinetic study

A simple, sensitive and specific liquid chromatography tandem mass spectrometry (LC‐ESI‐MS/MS) method was developed for the quantification of desvenlafaxine in human plasma using desvenlafaxine d6 as an internal standard (IS). Chromatographic separation was performed using a Thermo‐BDS hypersil C₈ column (50 × 4.6 mm, 3 µm) with an isocratic mobile phase composed of 5 mM ammonium acetate buffer: methanol (20:80, v/v), at a flow rate of 0.80 mL/min. Desvenlafaxine and desvenlafaxine d6 were detected with proton adducts at m/z 264.2/58.1 and 270.2/ 64.1 in multiple reaction monitoring positive mode, respectively. Liquid–liquid extraction was used to extract the drug and the IS. The method was linear over the concentration range 1.001–400.352 ng/mL with a correlation coefficient of ≥0.9994. This method demonstrated intra and inter‐day precision within 0.7–5.5 and 1.9–6.8%, and accuracy within 95.3–107.4 and 93.4–99.5%. Desvenlafaxine was found to be stable throughout the freeze–thaw cycles, bench‐top and long‐term matrix stability studies. The developed and validated method can be successfully applied for the bioequivalence/pharmacokinetic studies of desvenlafaxine in pharmaceutical dosage forms. Copyright © 2015 John Wiley & Sons, Ltd.     

Generalised Split Octonions and Their Transformation in SO(7) Symmetry

Generators of \(\operatorname{SO}(8)\) group have been described by using direct product of the Gamma matrices and the Pauli Sigma matrices. We have obtained these generators in terms of generalized split octonion also. These generators have been used to describe the rotational transformation of vectors in \(\operatorname{SO}(7)\) symmetry group.     

Novel Tin Complexes Containing an Oximato Ligand: Synthesis,Characterization, and Computational Investigation

Organotin complexes 1 – 6 of the general formula [SnR₂L] and [(SnR₃)₂L] (L=phenanthrenequinone dioximato – a bidentate ligand, R=Me, Bu, and Ph) were synthesized by the reaction of the sodium salt of the ligand H₂L (prepared in situ with MeONa) and SnR₂Cl₂/SnR₃Cl in 1 : 1 and 1 : 2 molar ratios. The physical and spectral properties of the newly synthesized complexes 1 – 6 are described. DFT and HF Calculations were performed to confirm the proposed structures.     

Preparation, structural analysis and dielectric properties of Bi x La1−x FeO3 perovskite

Rare earth element substituted bismuth ferrites (BiFeO₃) are of enormous importance as magnetoelectric materials. The polycrystalline samples of Bi _x La_1−x FeO₃ (x=0, 0.2, 0.4, 0.6, 0.8) were prepared by solid-state reaction using standard ceramic method. The single-phase formation of these compounds was confirmed by X-ray diffraction (XRD) studies. The samples with x=0, 0.2, 0.4, 0.6 are found to be orthorhombic while the sample with x=0.8 is triclinic. The dielectric constant (ε′) and dissipation factor (tan δ) were measured in the frequency range 100 Hz to 1 MHz at room temperature and as a function of temperature at certain fixed frequencies (1 kHz, 10 kHz, 100 kHz, 1 MHz). All the samples showed dielectric dispersion. The dielectric constant with temperature shows a broad peak; the peak temperature shifts with frequency which reflects the relaxor-type behavior. The peak above 600 K in the measured temperature range corresponds to antiferromagnetic ordering temperature (Néel temperature). The broadness of the peak changes with composition. The ac conductivity as well as ε′ are found to be maximum for the sample x=0.2 at room temperature.     

Magnetoelectric effect in cobalt ferrite-barium titanate composites and their electrical properties

CoFe₂O₄-BaTiO₃ composites were prepared using conventional ceramic double sintering process with various compositions. Presence of two phases in the composites was confirmed using X-ray diffraction. The dc resistivity and thermoemf as a function of temperature in the temperature range 300 K to 600 K were measured. Variation of dielectric constant (ɛ′) with frequency in the range 100 Hz to 1 MHz and also with temperature at a fixed frequency of 1 kHz was studied. The ac conductivity was derived from dielectric constant (ɛ′) and loss tangent (tan δ). The nature of conduction is discussed on the basis of small polaron hopping model. The static value of magnetoelectric conversion factor has been studied as a function of magnetic field.     

An exactly solvable quarkonium model and lower bounds on 3 p J decay rates

The exact 1P-state wavefunction R _1P (r) is obtained for the potential