RESUMEN
The nanocrystalline strontium cobalt molybdate composites of Sr1-xCoxMoO4 (x = 0, 0.3, 0.5, 0.7, 1) were prepared by mixing various mole ratios (SrM-1, SrCM-2, SrCM-3, SrCM-4 and CoM-5) and investigated for their humidity sensing properties. The composites were characterized by thermal analysis (TG/DTA), X-ray powder diffraction (XRD), Fourier Transform-Infrared spectroscopy (FT-IR), Fourier Transform Raman (FT-Raman) spectroscopy, Scanning Electron Microscopy (SEM/EDAX), Transmission Electron Microscopy (TEM) and UV-Visible absorption spectroscopy. The composites were subjected to dc electrical conductivity based humidity sensing studies at room temperature. The resistance measurements as a function of relative humidity (RH) in the range of 5-98% were carried out and the sensitivity factor (Sf) were calculated. The SrM-1 is found to possess with the highest Sf of 33014 ± 660 and CoM-5 is found to possess a low Sf of 868 ± 43. The SrCM-2, SrCM-3 and SrCM-4 possessed the sensitivity factors (Sf) of 915 ± 45, 3713 ± 185 and 3390 ± 102 respectively.
RESUMEN
In the title complex, [CoCl(2)(C(10)H(8)N(2))(2)]·3H(2)O, the Co(II) ion is situated on a twofold rotation axis and exhibits a slightly distorted octa-hedral geometry and is chelated by four N atoms of the two bidentate 2,2'-bipyridine ligands and two Cl(-) ions. The crystal packing is stabilized by hydrogen bonding formed between chloride ions and adjacent water mol-ecules. One of the two independent water molecules in the asymmetric unit is disordered over two sets of sites, each on a twofold rotation axis, in a 0.734â (17):0.269â (17) ratio.
RESUMEN
The Co centre in the title compound, [Co(C(14)H(11)N(2)O(2))(2)Cl(C(3)H(4)N(2))]·0.5H(2)O, shows a slightly distorted octa-hedral coordination geometry. The glyoximate units of the mol-ecule are linked by O-Hâ¯O hydrogen bonds with the H atom almost in the middle of the two O atoms. The crystal packing is stabilized through inter-molecular N-Hâ¯O, N-Hâ¯N and O-Hâ¯Cl hydrogen bonds. The uncoordinated water mol-ecule shows half-occupation.
RESUMEN
The title compound, trans-[Co(C(4)H(7)N(2)O(2))(2)Cl(C(10)H(14)N(2)S)]·0.5H(2)O, contains two independent mol-ecules in the asymmetric unit in which the Co(III) ions are coordinated in slightly distorted octa-hedral coordination environments. The bis-chelating glyoximate ligands, which occupy equatorial sites, are linked by interligand O-Hâ¯O hydrogen bonds. The dihedral angles between the mean planes of the glyoximate ligands in each mol-ecule are 2.07â (8) and 1.60â (1)°. The asymmetric unit contains a solvent water mol-ecule which is disordered over two sites with refined occupancies 0.64â (2) and 0.36â (2).
RESUMEN
In the title complex, [CoCl(C(12)H(8)N(2))(2)(H(2)O)]Cl·2.5H(2)O, the Co(II) ion is coordinated by four N atoms of two bis-chelating 1,10-phenanthroline (phen) ligands, one water mol-ecule and a chloride ligand in a distorted octa-hedral environment. The dihedral angle between the two phen ligands is 84.21â (3)°. In the crystal structure, complex mol-ecules and chloride ions are linked into centrosymmetric four-component clusters by inter-molecular O-Hâ¯Cl hydrogen bonds. Of the 2.5 solvent water mol-ecules in the asymmetric unit, two were refined as disordered over two sites with fixed occupancies of ratios 0.50:0.50 and 0.60:0.40, while another was refined with half occupancy.
RESUMEN
In the title compound, [Co(C(4)H(7)N(2)O(2))Cl(2)(C(4)H(8)N(2)O(2))], the Co(III) ion has a distorted octa-hedral coordination environment. The equatorial plane consists of four N atoms, two each from the dimethyl-glyoxime and dimethyl-glyoximate ligands, while the two axial positions are occupied by two chloride ions. Strong intra-molecular O-Hâ¯O hydrogen bonds are observed between the dimethyl-glyoxime and dimethyl-glyoximate ligands. Mol-ecules are linked into a chain running along the [101] direction by O-Hâ¯O and C-Hâ¯Cl hydrogen bonds. The chains are cross-linked through inter-molecular C-Hâ¯Cl hydrogen bonds.
RESUMEN
In the title mol-ecule, C(10)H(14)N(2)S, the n-butyl chain assumes a trans zigzag conformation. The dihedral angle between the pyridine ring and the thio-amide plane is 23.38â (8)°. The mol-ecules in the crystal structure are linked by an inter-molecular N-Hâ¯N hydrogen bond.
RESUMEN
OBJECTIVES: To test the efficacy of a bicarbonate-containing artificial physiologic tear solution (solution PT) in providing an environment in which the damaged corneal epithelium can recover its normal barrier function and to compare this solution with other available artificial tears. Also, to investigate the effects on the corneal mucin layer and epithelial ultrastructure. METHODS: The corneal epithelial permeability of anesthetized rabbits was increased by exposure to 0.1% benzalkonium chloride. The corneas were then exposed to solution PT, with or without bicarbonate, or one of four commercially available artificial tear solutions for 1.5 hours, followed by a 5-minute exposure to 5(6)-carboxyfluorescein. Frozen sections of the corneas were examined by fluorescence microscopy. The fluorescence intensity (FI) of the epithelium was measured by image analysis. Undamaged corneas exposed to tear solutions were examined by transmission electron microscopy after fixation of the mucin layer with cetylpyridinium chloride. RESULTS: The FI of corneas damaged by benzalkonium chloride was increased threefold above those of undamaged controls. Damaged corneas treated with either of two commercial isotonic tear solutions partially recovered their barrier function, but the FI did not reach control levels. Corneas treated with hypotonic solutions containing ethylenediaminetetraacetic acid (EDTA) did not recover. In contrast, the FI of corneas treated with solution PT returned to control levels. This effect was lost in the absence of bicarbonate. Solution PT and the two isotonic solutions maintained normal corneal ultrastructure and mucin layer. Lack of bicarbonate in solution PT resulted in focal damage to superficial epithelial cells, whereas the EDTA-containing solutions destroyed the first two cell layers and reduced the mucin thickness. CONCLUSIONS: Bicarbonate-containing solution PT is superior to the other tear solutions tested in promoting recovery of the damaged corneal epithelial barrier and maintaining normal ultrastructure. The presence of bicarbonate appears to be essential to this process.