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Electron paramagnetic resonance studies of the lead haloborate glass system xPbX-(30-x)PbO-68B2O3 (X=F2, Cl2, Br2 and x=5, 10, 15, 20 and 25 mol%) containing 2 mol% V2O5 as the paramagnetic probe were carried out at room temperature. These glasses were prepared using conventional melt quenching. The amorphous nature of the prepared glass samples was confirmed by x-ray diffraction studies. The EPR spectra were recorded at X-band frequencies with 100 kHz frequency modulation at room temperature. The spin-Hamiltonian parameters (SHP) of VO2+ ions, dipolar hyperfine parameter (P) and Fermi contact interaction parameter (K), molecular orbital coefficients (α2 and γ2), the number of spins participating in the resonance (N), and susceptibility (χ) have been evaluated. From the spin-Hamiltonian parameters it was observed that gA. From these results it was concluded that the vanadyl ions exist as VO2+ ions in octahedral coordination with tetragonal compression with C4V symmetry and the ground state is dxy. Tetragonality (Δg/Δg) of V4+ ion sites exhibited nonlinear variation with glass composition in all the glasses studied. This nonlinear variation might be due to changes in the ligand field at the site of V4+ion, indicating variation in octahedral symmetry. [ABSTRACT FROM AUTHOR]

Electron paramagnetic resonance (EPR) studies were made on 10Li2O-10Na2O-10K2O-xSrO-(68-x)B2O3-2V2O5 glasses. The glasses were prepared by the conventional melt quenching method and amorphous nature of the glass samples was confirmed by x-ray diffraction. From the EPR spectra the spin-Hamiltonian parameters were evaluated. It was observed that the V4+ ions are present as VO2+ vanadyl ions in octahedral coordination with tetragonal compression and belong to C4v symmetry, with dxy ground state. The measure of tetragonality Δg‖/Δg⊥ varies in a nonlinear manner with SrO content which may be due to change in the ligand field strength at the site V4+ ion site. The covalency rates indicated moderate covalency for the σ- and π-bonds. The number of spins participating in the resonance (N) and susceptibility (X) were evaluated, and found to vary with SrO content. [ABSTRACT FROM AUTHOR]

A simple and efficient method was developed to synthesis 2-(3-aryl-1,2,4-oxadiazol-5-yl)-N-phenylacetamide derivatives using acid chlorides from 3-(hydroxyimino)3-amino-N-phenylpropanamide. All the synthesized compounds were characterized by NMR and mass analyses. [ABSTRACT FROM AUTHOR]

Paraneoplastic neuropathies associated with leukemia are rare, and early diagnosis and treatment are crucial due to the potential for irreversible neurological deficits and delay in treatment of the leukemia. This is the first report to describe severe paraneoplastic orthostatic hypotension which resolved after treatment of the acute myeloid leukemia (AML). The patient is a 76 year-old woman who presented with progressive dizziness, anorexia, and fatigue. She had severe orthostatic hypotension (supine systolic blood pressure 186 mmHg and standing 79 mmHg). She was found to have AML, for which azacitidine was initiated, and orthostatic hypotension resolved after initiation of treatment. This case demonstrates a unique example of paraneoplastic sequelae remitting with treatment of the underlying hematologic neoplasm. Physicians should be aware of this unusual occurrence of autonomic neuropathy with AML as delay in treatment of the hematologic malignancy can lead to irreversible neurologic deficit and increased morbidity and mortality. [ABSTRACT FROM AUTHOR]

The mixed alkaline effect in double alkaline borate glasses MgO-BaO-B2O3 containing small proportions of copper oxide (CuO) has been studied. The glass samples are characterized by optical absorption, electron paramagnetic resonance (EPR), and Fourier transform infrared spectroscopy (FTIR). A red shift in optical absorption peaks with increasing MgO (decreasing BaO) concentration has been observed. The values of "g" tensor and hyperfine "A" tensor have shown inflections with glass composition. The number of spins (N) and paramagnetic susceptibility (X) also exhibited mixed alkaline effect. The broadening of glass network with increase in MgO concentration is found from the FTIR spectra. Interestingly both density and molar volume have shown decreasing trend with glass composition. The optical band gaps exhibited a nonlinear compositional dependence. As expected, the glass samples possessed higher values of optical basicity (⋀), molar electronic polarizability (αm), and Urbach energy (ΔE). [ABSTRACT FROM AUTHOR]

The mixed alkali effect (MAE) in a glass system containing three alkali ions (Li, Na and K) is studied. Glasses with the composition 10MgO-(x+y)Li2O-(15-x)Na2O-(15-y)K2O-60B2O3 [x=y=0, 2·5, 5, 7·5, 10, 12·5 & 15 mol%] were prepared using melt quenching. The glassy nature of the samples prepared was confirmed by XRD studies. In the glass system studied the alkaline earth oxide MgO content was kept constant while the content of the three alkali oxides was varied. The Tg values were calculated from differential scanning calorimetry (DSC) thermograms. The DC ionic conductivity was measured at different temperatures. The variation of conductivity followed the Arrhenius relation. The activation energies were calculated from the conductivity plots. The variation of conductivity with Li2O content was nonlinear and exhibited wave shaped curve. This type of variation may be attributed to the mixed alkali effect. The observed results were explained on the basis of the dynamic structure model (DSM) and the MAE observed in the present glass system may be attributed to the interaction between the alkali ions and between the alkali ions and the glass network. [ABSTRACT FROM AUTHOR]

EPR and DSC studies were carried out on MgO-R2O-B2O3-V2O5 glasses. The electron paramagnetic resonance spectra of V4+ ion in the ternary glass system xMgO-(30-x)R2O-70B2O3 (R = Li, Na, K) were recorded at X-band frequencies at 303 K. The V4+ ions in the present glass system exists as VO2+ ions in octahedral coordination with tetragonal compression. The site symmetry of vanadyl is C4v and the ground state of 3d1 ion is dxy. Tetragonality (Δg|/Δg⊥) of V4+ ion sites show a nonlinear variation with MgO content in the glasses. The covalency rates indicate moderate covalency for σ and π-bonds. The optical basicity values were also reported. Glass transition temperatures (Tg) of the glasses were found to increase linearly with increasing MgO content. [ABSTRACT FROM AUTHOR]