EVIDENCE OF PERMO-CARBONIFEROS GLACIATION IN THE BASAL MURBAT SANDSTONE FORMATION, SOUTHERN REGION, SULTANATE OF OMAN

The most massive basal diamictite of the Murbat Sandstone Formation exhibits many sedimentary features which indicate its subglacial deposition. Some of the most important features are: (1)straited and grooved sandstone slivers within the diamictete;(2)striated and faceted clasts; (3)small stratified sandstone lenses within the diamictite; (4)"dropstones" or "out-of-size clasts" in the shale; and (5) the large lateraal and vertical extent of the diamictite.
The overlying sequence of the Murbat Sandstone Formation consits of an alternating succession of conglaomerate and sandstone followed by silstone and shale, whose sedimentary structures, however, suggest their deposition in deeper-water basins.
The Murbat Sandstone Formation has been assigned to various ages ranging from Infra-Cambrian to Ordovician by different workers, in view of its isolated occurence and the absence of flora and fauna. The Metal Mining Agency of Japan, however, has dated the Murbat Sandstone Formation as Permo-Carboniferous, as it uncomfomably overlies Lower Carboniferous dikes of the crystalline Basement. The dikes have been dated by the K-Ar method.     

Chain-extended crystallization of polyethylene: effect of sample thickness

Films of polyethylene varying in thickness from 100 Å to 1 mm have been melted and recrystallized at 5kbar (1 bar ≡ 10⁵N/m²). All produced the spherulitic texture characteristic of chain-extended growth, but the average lamellar thickness increased with that of the specimen by a factor of about ten from hundreds to thousands of Å. The effect is discussed in terms of processes involved in the establishment of layer thickness. It also offers a means of removing the major difficulty in regarding lamellar thickening of polyethylene on annealing as a combination of melting and recrystallization.     

Experimental and analytical performance study of a thermosyphon water heater

The performance of a thermosyphon solar water heater was studied analytically and experimentally. A finite-difference model was used to predict year-round performance. Tests were conducted on an experimental heater subjected to acutal weather conditions in Benghazi, Libya. Satisfactory qualitative and quantitative agreement was found between experimental and predicted results. A storage volume of 60 liters per unit collector area was found to be optimum for Benghazi conditions. The day-end temperature was found to vary between 23° and 51°C for the test period, which occurred in winter, with an average of 41°C.     

Nutritional and bacteriological properties of some game duck carcasses

The aim of this work was to evaluate the body composition, bacteriological quality, proximate composition, amino acids content, total lipids fractionation, as well as fatty acids profile in breast and thigh meat (with skin) of males and females of two species of game ducks namely: Pintail (Anas acuta) and garganey (Anas querquedula). The obtained results are as follows. The live weight of pentail and garganey females constituted 59.0 and 86.0% of male's weight in pintail and garganey, respectively. The bacteriological quality revealed that the mean values of psychrotrophs, enterobacteriaceae, pseudomonas, coliforms, streptococci and Staph. aureus were 4.1, 2.8, 1.7, 2.0, 2.5 and 3.1 log 10 n/g of pintail breast muscle. The corresponding values in garganey breast muscle was 3.8, 3.2, 2.0, 3.0, 2.9 and 3.1, respectively. In the thigh of pintail and garganey, the results were more or less different. Neither salmonella nor Clostridium perfringens could be isolated from examined game duck carcasses. Protein content ranged from 19.0 to 23.8%, fat 4.8 to 23.2%, ash 1.0 to 1.4% and energy value 580 to 1191 kJ/100 g in pintail meat against 20.8 to 23.3% protein, 9.3 to 16.1% fat, 1.3 to 1.4% ash and 741 to 952 kJ/100 g in garganey meat. Breast meat of pintail recorded high content of iron (5.12 and 6.19 mg/100 g wet basis) in males and females, respectively, against 4.22 and 6.14 mg/100 g in garganey meat. The essential amino acids content ranged from 34.3 to 38.6 g/100 g protein in pintail meat against 36.3 to 38.1 g/100 g protein in garganey meat. The total lipids of pintail and garganey were fractionated to seven fractions. The major fatty acids in pintail and garganey lipids were oleic, palmitic and stearic. Besides, garganey lipids had more unsaturated fatty acids content compared with pintail.     

Nucleation of Fe-intermetallic phases in the Al-Si-Fe alloys

Nucleation of Fe-intermetallic phases (i.e. binary Al-Fe, α-AlFeSi, β-AlFeSi, δ-AlFeSi, and q₁-AlFeSi phases) on the surface of different inclusions in six experimental Al-Si-Fe alloys was studied through a quantitative evaluation of the number of inclusion particles that have a direct physical contact with the nucleated phase as seen through the optical microscope. It was found that nucleation of each of the Fe-intermetallic phases was promoted on the surface of several inclusions under the same conditions of alloy composition and cooling rates. Some inclusions exhibited high potency for the nucleation of particular Fe-intermetallic phases under certain conditions and poor potency under other conditions. The potent nucleants for the primary α-Al phase such as γ-Al₂O₃ exhibited poor potency for the nucleation of the Fe-intermetallic particles that lie within the primary phase (intragranular particles). Reactive inclusions such as CaO and SiC are very potent nucleants for the intragranular Fe-intermetallic phase particles. The nucleation of the Fe-intermetallic phases in Al-Si-Fe alloys obeys the general features of nucleation, in particular, the effect of cooling rate and solute concentration on the potency of the nucleant particles: (1) it was observed that increasing the cooling rate enhances the heterogeneous nucleation of the Fe-intermetallic phases on the surface of different inclusions, and (2) the nucleation potency of inclusion particles in both α-Al and interdendritic regions improves with increasing solute concentration up to a certain level. Above this level, the solute concentration poisons the nucleation sites. Nucleation of the Fe-intermetallics in the alloys studied does not seem to be largely affected by the type of the nucleating surface.     

Geometric Design of Pyramidal Antenna Arrays for Hemispherical Scan Coverage

An approach is presented for optimizing the geometry of pyramidal antenna arrays, given a full azimuth and a full or limited elevation scan requirement. It involves choosing the best face elevation and number of faces of the pyramid, which minimize the maximum scan angle while maximizing the geometric directivity. The analysis shows that the 4-face pyramid is the best choice. The derivation assumes that the distance to the antenna is infinite (the true far-field case). However, when finite distances are considered, the maximum scan angle increases only slightly at the minimum far-field distance used for low sidelobe pattern measurement     

Anionic/Cationic Membranes Obtained by a Radiation Grafting Method for Use in Waste Water Treatment

Investigations were carried out on different ionic membranes, which were prepared by radiation-induced graft copolymerization. Cationic (low density polyethylene (LPDE)-g-poly(acrylic acid) (PAAc)) and cationic/anionic (LDPE-g-P(AAc/4-vinyl pyridine (4VP)) membranes) were used to elucidate the possibility of their practical use. The metal uptake via their functional groups was determined by using atomic absorption and X-ray fluorescence. The amount of metal uptake by the prepared membranes increased significantly as the pH of the metal feed solution increased (pH ≤ 5·3) and the chelated metal ions were easily desorbed by treating the membrane with 0·1 M HCl for 2h at room temperature. The maximum uptake for a given metal was higher for the cationic/anionic membranes than for the cationic ones. The selectivity of the cationic/anionic membranes towards different metals was investigated using mixtures of two or three metals in the same feed solution. The membranes showed high selectivity towards Fe(III ) ions. Characterization of the graft copolymers containing metals was determined by thermogravimetric analysis (TGA) and X-ray diffraction (XRD). TGA results showed that the decomposition of the graft copolymer in the presence of chelated metal ion occurred at temperatures above 300°C. The XRD of LDPE-g-P(AAc/4VP) treated with Fe(III ) at various concentrations showed that the crystallinity decreased to a certain limiting value. The complexed copolymers could be recycled several times and showed high selectivity to the Fe(III ) ion in the presence of the other metal ions investigated. This may make such grafted membranes acceptable for practical use in waste water treatment. © 1997 SCI     

Rigorous optimization of heat-integrated and Petlyuk column distillation configurations based on feed conditions

The steady-state design and rigorous simulation of conventional distillation configurations and several energy-integrated configurations has been studied for ternary mixture separation. The studied configurations are optimized rigorously based on total annual cost as the economic objective function. The energy-integrated distillation configurations are compared with conventional configurations to find the maximum achievable total annual cost savings. Changing feed conditions is considered as one of the optimization variables by investigating different states of feed conditions; feed at 15.5°C temperature, liquid at bubble point and vapor at dew point. The investigated configurations are conventional direct and indirect separation sequence, heat-integrated direct sequences, Petlyuk column, heat-integrated sloppy sequence, and double heat-integrated sloppy sequence. Optimization results indicate that saving in energy and total annual cost of the configurations is affected by the states of the feed conditions.