Showing papers by "Jordan University of Science and Technology published in 1983"

The stratigraphy and structure of the Crag of mid-Suffolk, England

Abstract: Glauconite-coated flints at the base of a recently recognized spread of Crag deposits are thought to have been derived from a formerly more extensive basal Bullhead Bed of the Thanet Beds. No lithological basis has been found for subdividing the Crag into Norwich and Red Crag, although the faunal criteria for separating these two Crags is of chronological significance. A number of sub-drift northeasterly trending faults and fault-guided Crag basins have been identified. The age of these structures is thought to be early Pleistocene and there was probably syndepositional movement along the faults.

Spectroscopic and Conductometric Investigation of the Interaction of Azithromycin with Iron (II) Ion

Abstract: The interaction of the antibiotic azithromycin with ferrous sulfate and ferrous perchlorate in methanol has been investigated by spectroscopic and conductometric methods under equilibrium conditions. The interaction of azithromycin with both salts has been found to form one complex with metal to ligand composition of 1:1. The value of log Kf calculated from the absorption spectra for FeSO4-azithromycin complex at 25˚C was 5.16 ± 0.07 (Kf = 1.4 x 10 5 M -1 ). The value of log Kf for Fe(ClO4)2-azithromycin complex calculated from the conductivity measurements at 25˚C was 5.20 ± 0.08 (Kf = 1.6 x 10 5 M -1 ). The enthalpy and entropy of complexation were determined from the temperature dependence of the complexation constants. The ∆H o and ∆S o were 103.8 kJ/mol and 486.9 J/mol.K, respectively. The calculated molar conductivity of the Fe(ClO4)2-azithromycin complex at 25˚C was 99.7 S cm 2 mol -1 . This high molar conductivity has been considered indicative of the formation of a charged complex formed from the coordination of the neutral azithromycin ligand to the iron (II) ion without being accompanied by loss of protons.

The Effect of Applied Potential on Plasmon Resonance Bands of Nanoscopic Silver Particles Adsorbed on Transparent Electrodes

Abstract: The plasmon resonance spectra of nanoscopic silver particles adsorbed on transparent semiconductor electrodes in contact with eight aqueous electrolytes (KCl, KBr, KI, NaCl, NaBr, NaI, NaClO4, and KPF6) have been examined. In all electrolytes, the plasmon resonance bands are red-shifted and decreased in intensity as the applied potential is made more positive. The degree of the potential-induced spectral changes depends on the electrolyte type and concentration. The change in plasmon absorption band is largest for the higher concentration. At constant concentration, the potential-induced spectral changes are largest in the presence of I - , Cl - and Br - anions and smallest in the presence of PF6 - and ClO4 - anions. The largest effects for particles in contact with I - , Cl - and Br - anions may arise from more severe reduction in electron mean free lifetime and/or the formation of a metal-adsorbate complex which is highly absorbing in the spectral region of the plasmon resonance band.

Determination of Nitrite and Nitrate in Cell Culture Medium by Reversed-Phase High-Performance Liquid Chromatography with Simultaneous UV-VIS and Fluorescence Detection

Abstract: A reliable method for determination of nitrite and nitrate in cell culture medium has been developed. The method is based on pre-column derivetization of nitrite with 2,3diaminonaphthalene (DAN) under acidic medium to yield 2,3-naphthotriazole (NAT). For determination of nitrate, it was converted to nitrite by nitrate reductase before the derivetization step. NAT was separated on a 5 µm C18 column (250x4.6 mm, I.D) guarded by a 10 µm C18 column (20X4.6 mm, I.D), and eluted with 15 mM phosphate buffer (pH 7.5) containing 35% acetonitrile (flow rate 1.0 mL/min). Average retention time of NAT was 12.4 min. Absorbance of NAT was monitored at 369 nm and its fluorescence was monitored at 375 nm for excitation and 415 nm for emission. Calibration curves of nitrite or nitrate were linear in the range 0.03-2.0 µM for fluorescenc detection and 0.5-50 µM for UV-VIS detection. Correlation coefficients were better than 0.994 and mean recoveries were 96±7 %.

Field Meeting: A traverse of the Weald, 6 June 1982

Abstract: During the meeting members were able to study the lithologies, and some faunas, of nearly all the formations and their members from the Atherfield Clay to the Gault in the area between Fittleworth and Storrington, Sussex.