Toxicity of organophosphorus pesticide sumithion on larval stages of stinging catfish <Emphasis Type="Italic">Heteropneustes fossilis</Emphasis>

Sumithion is widely used to control brittle in paddy fields and tiger bug in fish larval rearing ponds. The objective of this study was to elucidate the toxic effects of sumithion on larval stages of stinging catfish Heteropneustes fossilis. Larvae were exposed to two concentrations (150 and 250 μg/L) of sumithion with one control in three replicates of each. Larvae samples were collected at 20- and 24-h intervals followed by observation under a digital microscope. Exposures of stinging catfish larvae to sumithion produced deformities including irregular head shape, lordosis, yolk sac edema, body arcuation, tissue ulceration, etc. The mortality rates of larvae were significantly increased in response to increase in sumithion concentrations. Furthermore, around 30% of the total adult stinging catfish reared in sumithiontreated aquaculture ponds were found to be deformed permanently. These findings highlight that exposure of stinging catfish to sumithion at the critical and sensitive stages in their life cycle may significantly reduce the number of returning adults. Therefore, the use of sumithion for crop protection needs to be considered carefully and alternatives to sumithion should to be developed for controlling aquatic insects in aqua-ponds during larval rearing.     

Organic tracers in sediments from the coastal zone of Ras Abu el-Darag,Gulf of Suez

Sediment samples from the coastal zone of the Gulf of Suez contain a variety of organic compounds from anthropogenic and natural sources. A total of 12 surface samples of bottom sediments were collected with an Ekman grab sampler along an off-shore transect south of Ras Abu el-Darag. The samples were extracted with a mixture of dichloromethane and methanol (3:1 v/v) after drying and sieving through 250 μm mesh. The extracts were derivatized and analyzed by gas chromatography–mass spectrometry in order to characterize the chemical composition and sources of the organic components. Marine with minor terrestrial biota were the major natural sources of organic tracers and included n-alkanoic acids, sterols and saccharides (5.7–76.7%). Anthropogenic sources, from petroleum related activities, detergent usage for spill cleaning and littering, are indicated by the presence of n-alkanes with carbon preference index ≤1.0, hopanes, steranes, unresolved complex mixture of branched and cyclic hydrocarbons, alkyl nitriles, alkamides and plasticizers. Their total relative concentrations ranged from 23.3 to 97.3% of the total extracts. Petroleum residues from natural seepage may also be part of these hydrocarbons. The levels of anthropogenic inputs decrease from about 94% in coastal zone sediments to about 20% in sediments from the reef front.     

Padé approximant calculations for the number of scattering during particle diffusion

The mean number of particle scattering in a semi-infinite and finite slab for arbitrary energy sources are calculated by Padé approximants. Uniform source distribution is considered for the finite slab. For the semi-infinite medium we calculatethe number of particles due external radiation and at a particular point in the medium. Numerical calculations and comparisons were performed.     

Source flow expansion of monatomic gas into vacuum under external field of forces

The steady flow expansions of monatomic gases consisting of Maxwellia molecules into a vacuum moving under external forces with a source of spherical symmetry are investigated. The analysis is based on the B-G-K model of the Boltzmann equation with the approximation in hypersonic limit. The kinetic equation is solved by using the moment method. Analytical forms for the density and temperature are obtained for small and large distances from the source. The results show that the temperature in free expansion is less than that in the case of the expansion under the influence of external field of forces.     

Radiative transfer in an infinite cylinder

The problem of radiation transfer in a cylinder with diffuse reflectivity and containing an energy source is connected with the source-free radiation transfer problem with isotropic boundary condition. Equation for the radiation heat flux is obtained for a polynomial source. In the special case of isotropic scattering, the radiation heat flux is given in terms of the albedo of the second problem. An expression is also given for the net radiation heat flux.     

Radiation transfer in inhomogeneous dispersive media

Equations for the angular density of radiation, reflected and transmitted intensities associated with radiation scattered by inhomogeneous dispersive media are obtained. The Padé approximant technique is used to calculate these intensities in inhomogeneous and homogeneous media. The results for the [0/1] Padé approximant lead to numerical results that compared with the exact results.     

Spectral photometry of selected areas of the lunar surface during maximum solar activity

Photoelectric observations have been carried out during maximum solar activity in order to investigate the variation of the brightness of the lunar surface with the solar cycle and to detect the possiblity of existing colour anomaly. The brightness data, using a wide-passband filter, do not show any evidence of variation with the solar cycle. No colour anomaly is found for the investigated lunar regions, and the doubt that has been felt by some investigators about the nonexistence of certain colour indices' variation with phase is not confirmed.     

Pan-African high-grade metamorphism of southern Sinai,Egypt, fluid inclusion evidence

Fluid inclusions in the leucosomes of Wadi Feiran migmatites showed that CO ₂ , H₂O and (H₂O-CO₂) fluids were likely to have been present when partial melting began in these rocks. Low salinity, aqueous fluid, to a lesser extent, CO₂-rich fluids are the most abundant fluids. The present study suggests that high-density CO₂ inclusions were formed at the earliest stage, while H₂O inclusions were formed at the late stage. In an intermediate stage, low-density CO₂ and H₂O, CO₂ inclusions were formed. At the early stage of uplift and during melt crystallization, the CO₂-bearing vapour was trapped at grain boundaries. At the late stage of uplift, H₂O released at the time of crystallization of the melt was trapped as inclusions.     

Platinum-group elements distribution and spinel composition in podiform chromitites and associated rocks from the upper mantle section of the Neoproterozoic Bou Azzer ophiolite, Anti-Atlas, Morocco

The distribution of platinum-group elements (PGEs), together with spinel composition, of podiform chromitites and serpentinized peridotites were examined to elucidate the nature of the upper mantle of the Neoproterozoic Bou Azzer ophiolite, Anti-Atlas, Morocco. The mantle section is dominated by harzburgite with less abundant dunite. Chromitite pods are also found as small lenses not exceeding a few meters in size. Almost all primary silicates have been altered, and chromian spinel is the only primary mineral that survived alteration. Chromian spinel of chromitites is less affected by hydrothermal alteration than that of mantle peridotites. All chromitite samples of the Bou Azzer ophiolite display a steep negative slope of PGE spidergrams, being enriched in Os, Ir and Ru, and extremely depleted in Pt and Pd. Harzburgites and dunites usually have intermediate to low PGE contents showing more or less unfractionated PGE patterns with conspicuous positive anomalies of Ru and Rh. Two types of magnetite veins in serpentinized peridotite, type I (fibrous) and type II (octahedral), have relatively low PGE contents, displaying a generally positive slope from Os to Pd in the former type, and positive slope from Os to Rh then negative from Rh to Pd in the latter type. These magnetite patterns demonstrate their early and late hydrothermal origin, respectively. Chromian spinel composition of chromitites, dunites and harzburgites reflects their highly depleted nature with little variations; the Cr# is, on average, 0.71, 0.68 and 0.71, respectively. The TiO₂ content is extremely low in chromian spinels, <0.10, of all rock types. The strong PGE fractionation of podiform chromitites and the high-Cr, low-Ti character of spinel of all rock types imply that the chromitites of the Bou Azzer ophiolite were formed either from a high-degree partial melting of primitive mantle, or from melting of already depleted mantle peridotites. This kind of melting is most easily accomplished in the supra-subduction zone environment, indicating a genetic link with supra-subduction zone magma, such as high-Mg andesite or arc tholeiite. This is a general feature in the Neoproterozoic upper mantle.     

DHI evaluation by combining rock physics simulation and statistical techniques for fluid identification of Cambrian-to-Cretaceous clastic reservoirs in Pakistan

The use of seismic direct hydrocarbon indicators is very common in exploration and reservoir development to minimise exploration risk and to optimise the location of production wells. DHIs can be enhanced using AVO methods to calculate seismic attributes that approximate relative elastic properties. In this study, we analyse the sensitivity to pore fluid changes of a range of elastic properties by combining rock physics studies and statistical techniques and determine which provide the best basis for DHIs. Gassmann fluid substitution is applied to the well log data and various elastic properties are evaluated by measuring the degree of separation that they achieve between gas sands and wet sands. The method has been applied successfully to well log data from proven reservoirs in three different siliciclastic environments of Cambrian, Jurassic, and Cretaceous ages. We have quantified the sensitivity of various elastic properties such as acoustic and extended elastic (EEI) impedances, elastic moduli (K _sat and K _sat–μ), lambda–mu–rho method (λρ and μρ), P-to-S-wave velocity ratio (V _P/V _S), and Poisson’s ratio (σ) at fully gas/water saturation scenarios. The results are strongly dependent on the local geological settings and our modeling demonstrates that for Cambrian and Cretaceous reservoirs, K _sat–μ, EEI, V _P/V _S, and σ are more sensitive to pore fluids (gas/water). For the Jurassic reservoir, the sensitivity of all elastic and seismic properties to pore fluid reduces due to high overburden pressure and the resultant low porosity. Fluid indicators are evaluated using two metrics: a fluid indicator coefficient based on a Gaussian model and an overlap coefficient which makes no assumptions about a distribution model. This study will provide a potential way to identify gas sand zones in future exploration.