Coordination mode of cyclohex-1-enylolonium cation and bridging pyridyl derivatives as gem-diol chelates to rhenium(I) and (VII)

Transition Metal Chemistry - Rhenium(I) and (VII) complexes with cyclohex-1-enylolonium cation and bridging pyridyl derivatives are reported. Additionally, the CO-bridged pyridyl and their related...     

Gamma—rings and multiplications on abelian groups

If M and Γ are abelian groups, then M will be a Γ-ring iff there exists a group homomorphism f from Γ into the group of all multiplications of M, Mult(M), such that f(Γ) satisfies the Generalized Associativity Property on M. In this note we examine the following special cases of this result: (i) M is a Γ-ring satisfying the Nobusawa Condition, (ii) M is a cyclic group, (iii) M is a direct sum of cyclic groups and (iv) M is a Γ-ring that has unity elements.     

Water and the relationship to the crystal structure stability of azithromycin

Journal of Thermal Analysis and Calorimetry - This study investigated the solid-state physical stabilities of azithromycin dihydrate (AZM-DH), thermally prepared anhydrate and hemihydrate...     

Effect of the annealing environment on the optical properties of ZnO/GaAs grown by MOCVD

The optical properties of ZnO grown on (1 0 0) GaAs substrate using metalorganic chemical vapor deposition are investigated by photoluminescence (PL) spectroscopy. Postgrowth annealing in nitrogen and oxygen was performed for different times and temperatures in order to incorporate As from the substrate into the ZnO thin films. The PL spectra of the samples annealed in different ambients reveal that the effect of As diffusion into the ZnO thin films is more pronounced when the annealing is performed in oxygen at 550 °C. The 11 K PL spectra show the appearance of a transition at ∼3.35 eV after annealing in oxygen at 550 °C for 1 h. A further increase in the annealing temperature leads to the disappearance of this line, while for annealing times longer than 2 h at 550 °C, it is no longer prominent. The increase in intensity of this new transition is also accompanied by the enhancement of radiative centers related to structural defects, such as the stacking fault-related transition at 3.31 eV and the Y-line. Temperature dependent PL illustrates the excitonic nature of the new transition at ∼3.35 eV, which is therefore assigned to (A⁰, X) transition, where the acceptor is possibly the 2V_Zn-As_Zn complex, with an activation energy E_A in the range of 160-240 meV. Furthermore, the enhancement of the radiative centers related to structural defects is regarded as evidence that As atoms tend to segregate in the vicinity of structural defects to relieve local strain.     

Electrical characterization of deep levels in n-type GaAs after hydrogen plasma treatment

Deep level transient spectroscopy (DLTS) and Laplace-DLTS (L-DLTS) have been used to investigate defects in an n-type GaAs before and after exposure to a dc hydrogen plasma (hydrogenation). DLTS revealed the presence of three prominent electron traps in the material in the temperature range 20-300 K. However, L-DLTS with its higher resolution enabled the splitting of two narrowly spaced emission rates. Consequently four electron traps at, E_C—0.33 eV, E_C—0.36 eV, E_C—0.38 eV and E_C—0.56 eV were observed in the control sample. Following hydrogenation, all these traps were passivated with a new complex (presumably the M3), emerging at E_C—0.58 eV. Isochronal annealing of the passivated material between 50 and 300 °C, revealed the emergence of a secondary defect, not previously observed, at E_C—0.37 eV. Finally, the effect of hydrogen passivation is completely reversed upon annealing at 300 °C, as all the defects originally observed in the reference sample were recovered.     

Prime radicals in sandwich near-rings

In a previous work [3], the current author, together with P. R. Hall, studied various kinds of primeness in near-rings and sandwich near-rings of continuous functions. In this paper, we study various prime radicals for sandwich near-rings. In certain cases, complete characterisations of the prime, 3-prime, equiprime and strongly equiprime radicals are obtained.     

The influence of various dielectric parameters on the reststrahlen region of SiC

The reststrahlen region of SiC is analysed with the goal of establishing the origin of different shapes of this band, by varying the dielectric parameters involved when simulating the reststrahlen region as obtained by infrared reflectance.     

14-Hydroxy-14-phenyldibenzo[a,j]xanthene as a lattice host: crystal and molecular structure of its (1:1) complex with diethyl ether

The title compound 14-hydroxy-14-phenyldibenzo[a,j]xanthene 1 formed a (1:1) complex with diethyl ether. 1,4-Dioxane was also enclathrated, but with a variable stoichiometric ratio. Single crystal X-ray crystallography was used to elucidate the crystal structure of the 1·diethyl ether complex. Crystals are orthorhombic with space group P2₁2₁2₁, a = 8.532(3), b = 15.040(4), c = 18.491(5) Å, V = 2373(1) ų, d _c = 1.256 g/cm³, and Z = 4. Host and guest molecules were found to associate via hydrogen bonds, with the guest molecules residing in undulating channels lined by host molecules.