Vol. 6 Issue 3
T.M. Ghazal
The purpose of this paper is to give several observations about the orientability of spherical fibrations with respect to generalized cohomology theories, and we shall give an example of a spherical fibration which is orientable with respect to mod p K-theory but not with respect to p-local K-theory.
Mohamed M.T. Limam
Prediction limits are developed for a future observation of the random one-way model. If the variance ratio is known, one may obtain exact prediction limits. For settings where the variance ratio is known, we describe a procedure based on the Satterthwaite approximation. The exact confidence level of the approximate limits has been studied by computer simulation experiments. This study shows that this approximation is acceptably for a wide range of cases.
A.M. El-Gendy, M.El-Safty, A. Essawy and H.Y. Moustafa
The benzoxazine (I) reacted with primary amines and yielded the carbamoyl acetanilide derivatives (II a-c), and aniline in boiling benzene/ phosphorus oxychloride gave the quinazolinone (III). (I) reacted with secondary amines and gave the carbonyl acetanilide derivative (IV). Hydrazinolysis of (I) gave the quinazolinone (V a & b). Compound (V a) condensed with aromatic aldehydes and reacted with phosphorus pentasulphide to give (VI a-d) and (VII) respectively. The reaction of active methylene compounds with (I) gave (VIII) or (IX) respectively. Also (I) reacted with formamide to yield (X) and with sodium azide in boiling acetic acid to give (XI) and (XII) respectively.
Souad F. Al-Azzawi and Akl M. Awwad
Excess molar volumes, viscosities, excess viscosities and excess molar activation energies of viscous flow are reported for binary mixtures of sulfolane with benzene, toluene, p-xylene and mesitylene. The excess molar volumes, excess viscosities and excess molar activation energies of viscous flow are negative over the whole mole fraction range at 298.15K
S.A. Al-Tamrah
An accurate colorimetric method was developed for the determination of 0.5 µ/ml of p-benzoquinone, hydroquinone and paracetamol. The method is based on the reaction of p-benzoquinone with piperazine at pH 5.4. The absorbance of the complex formed is measured at 363 nm. The method was applied for the analysis of mixtures of p-benzoquinone and hydroquinone and to the determination of paracetamol in some pharmaceutical preparations. The relative standard deviation is less than 1%.
Khalid A. Al-Rashood and M.E. Mohamed
Lead, cadmium, copper and zinc in part-per-billion (ppb) levels in laboratory tap water were determined by differential pulse anodic stripping voltammetry (DPASV). Triammonium citrate (0.2 M) was used as a supporting electrolyte. Differential pulse anodic stripping voltammograms for samples prior to and after spiking were recorded in the potential range - 1.2 to 0.0 volts by a microprocessor-controlled polarographic analyser. The indicator electrode used was static mercury drop electrode (SMDE) combined with Ag/AgCl (KCl sat.) reference electrode and a platinum auxiliary electrode. The results obtained by adopting standard additions method showed relative standard deviations less than 10%.
Faig El Schami
This paper deals with hydrogeological, hydrochemical and hydrogeochemical investigations of the three main springs of Khatt, which issue from the karstic limestone formation at the foot of the Musandam range South of Ras Al Khamiah.
The hydrochemical composition of the spring reflects the meteoric genesis of the thermal springs, with Na2SO4 type water.
Tritium and carbon-14 data indicate, that the spring is probably receiving water from deeper sources.
G.A. Sorial and W.H. Granville
Adsorption equilibria in the oxygen-nitrogen-4A molecular sieve pellets system are determined at two pressures of 1.7 and 4.4 bar and three temperatures 278.15, 293.15 and 303.15 K. The corresponding pure component isotherms for both gases are also determined at the same temperatures and at pressures up to 8 bar. The binary experimental data have been found to be predicted within a good accuracy by the ideal adsorbed solution theory of Myers and Prausnitz, Cooks and Bamadjian model and the statistical thermodynamic model of Ruthven et al. Fair agreement was obtained with the vacancy solution model of Suwanayuen and Danner.
Mostafa S. Afifi
The current distribution on the surface of an offset parabolic reflector antenna is analyzed for multimode pyramidal horn feeds. The diagonal horn feed, which gives good symmetric current distribution on the reflector surface, yields high levels of depolarized fields. These are in the order of -16 dB, and form four quadrants on the surface, alternating between positive and negative polarity, around the reflector center. Adequate compensation of this depolarization is not easy. For example, the use of large percentage mix from the TM21 mode (for vertical polarization), could only reduce these depolarization current levels to -26 dB. The depolarized currents are minimized, however, by selection of the mixture ratio of specific modes in regular pyramidal horns. Depolarization levels below -40 dB (from the main polarization level) are achieved for vertical polarization (which is parallel to the offset axis of symmetry), using the fundamental TE10 mode, with small percentage mix of the TE11 mode. For horizontal polarization, the small percentage mix needed is from the TE20 mode. In this situation the depolarization level is reduced to only -34 dB. (noting that the depolarization level of the fundamental mode, alone, is -26 dB)
S. Ayyash and M. Rasas
A relationship between daily atmospheric transmittance and the daily range of air temperature was proposed for calculating incident solar radiation. The proposed formula has been applied to solar radiation and air temperature data of Kuwait. It is shown that the daily temperature difference accounts for 74-81% of the variation in daily solar radiation. It is also shown that the same solar radiation data set correlates equally well with temperatures recorded at weather stations having marked differences in the daily temperature range.