Chemical composition of soil vermiculite clays as related to their genesis

Chemical and mineralogical analyses of the clay fraction of eleven soils containing a large amount of vermiculite clay and representing a wide range of parent materials revealed that two types of vermiculite clays exist: (1) An aluminous type in which Al³⁺ substitutes for Si⁴⁺ in tetrahedral positions in the same order of magnitude as in the coarse grained vermiculites and micas, and with Al³⁺ as the dominant octahedral ion. (2) A silicious type in which only Si⁴⁺ occupies the tetrahedral positions, and with Fe³⁺ and Mg²⁺ as the dominant octahedral ions. The aluminous vermiculite clay was found to occur in soils derived from acid igneous rocks and is usally associated with mica, whereas the silicious type was found to occur in soils derived from basic igneous rocks which do not contain mica. Because of this close association of these two types to their parent material, it was concluded that the aluminous vermiculite is a product of alteration of mica whereas the silicious type is a product of synthesis from primary oxides of silica, alumina, iron, and magnesium. Both types of vermiculite clays tend to be dioctahedral in contrast to the trioctahedral nature of the coarse-grained vermiculite.     

Theoretical basal Ca II fluxes for late-type stars: results from magnetic wave models with time-dependent ionization and multi-level radiation treatments

In the current study we present ab initio numerical computations of the generation and propagation of longitudinal waves in magnetic flux tubes embedded in the atmospheres of late-type stars. The interaction between convective turbulence and the magnetic structure is computed and the obtained longitudinal wave energy flux is used in a self-consistent manner to excite the small-scale magnetic flux tubes. In the current study we reduce the number of assumptions made in our previous studies by considering the full magnetic wave energy fluxes and spectra as well as time-dependent ionization (TDI) of hydrogen, employing multi-level Ca II atomic models, and taking into account departures from local thermodynamic equilibrium. Our models employ the recently confirmed value of the mixing-length parameter \(\alpha=1.8\). Regions with strong magnetic fields (magnetic filling factors of up to 50%) are also considered in the current study.The computed Ca II emission fluxes show a strong dependence on the magnetic filling factors, and the effect of time-dependent ionization (TDI) turns out to be very important in the atmospheres of late-type stars heated by acoustic and magnetic waves. The emitted Ca II fluxes with TDI included into the model are decreased by factors that range from 1.4 to 5.5 for G0V and M0V stars, respectively, compared to models that do not consider TDI.The results of our computations are compared with observations. Excellent agreement between the observed and predicted basal flux is obtained. The predicted trend of Ca II emission flux with magnetic filling factor and stellar surface temperature also agrees well with the observations but the calculated maximum fluxes for stars of different spectral types are about two times lower than observations. Though the longitudinal MHD waves considered here are important for chromosphere heating in high activity stars, additional heating mechanism(s) are apparently present.     

Periodic solutions and their stability for the problem of gyrostat

The Hamiltonian function of the problem of gyrostat is written in terms of Deprit's transform. The periodic solutions, using Lie's transform, are given and the condition for their stability is carried out.     

The rotational temperature of the FeH molecules in a large sunspot

Equivalent widths for four FeH bands (0–0), (1–0), (2–0), and (2–1) versus rotational quantum number J have been used to determine the rotational temperature of the molecule. The average value obtained from the first three bands is $T_{\mathit{rot}}=2900\mathrm{K}\pm 300\mathrm{K}$. This result agrees well with the temperatures derived for other molecules in sunspot umbrae. The current value is notably higher than that obtained earlier by (Mulchaey, J.S., 1989. Pub. Astron. Soc. Pacific 101, 211) for the same molecule.     

Batch and continuous removal of heavy metals from industrial effluents using microbial consortia

Bio-removal of heavy metals, using microbial biomass, increasingly attracting scientific attention due to their significant role in purification of different types of wastewaters making it reusable. Heavy metals were reported to have a significant hazardous effect on human health, and while the conventional methods of removal were found to be insufficient; microbial biosorption was found to be the most suitable alternative. In this work, an immobilized microbial consortium was generated using Statistical Design of Experiment (DOE) as a robust method to screen the efficiency of the microbial isolates in heavy metal removal process. This is the first report of applying Statistical DOE to screen the efficacy of microbial isolates to remove heavy metals instead of screening normal variables. A mixture of bacterial biomass and fungal spores was used both in batch and continuous modes to remove Chromium and Iron ions from industrial effluents. Bakery yeast was applied as a positive control, and all the obtained biosorbent isolates showed more significant efficiency in heavy metal removal. In batch mode, the immobilized biomass was enclosed in a hanged tea bag-like cellulose membrane to facilitate the separation of the biosorbent from the treated solutions, which is one of the main challenges in applying microbial biosorption at large scale. The continuous flow removal was performed using fixed bed mini-bioreactor, and the process was optimized in terms of pH (6) and flow rates (1 ml/min) using Response Surface Methodology. The most potential biosorbent microbes were identified and characterized. The generated microbial consortia and process succeeded in the total removal of Chromium ions and more than half of Iron ions both from standard solutions and industrial effluents.     

Correlation of the radiometric survey data and the structural analysis with the geology of Abu Zawal Area,Central Eastern Desert,Egypt

Abu Zawal area is located nearly north of the midway of Qena-Safaga road, and is about 250 square kilometres. It is built of a sequence of igneous and metamorphic rocks of Late Precambrian age.It has been subjected to geological, radiometrical, and structural investigations to reveal the structural setting of the area and its relation to the trends of mineralization, as well as the distribution of the radioactivity in the different rock units, cropping out in the studied area. Therefore, each rock unit has been characterized statistically by a certain radiometric background through the radiometric survey traverses. Besides, application of certain statistical inference tests could find the relations that might exist between the different rock types of Abu Zawal area and their corresponding ones in other studied areas.It has been found that the least radioactivity is associated with the basic metavolcanic rocks, while the highest values are associated with the Late Orogenic Plutonites and related rocks, and the granodiorites represent a moderate level of radioactivity. The study revealed that the Late Orogenic Plutonites of Abu Zawal area might be of younger age than their corresponding ones at the north of the Eastern Desert.Investigation of the two conjugate shear joints for the whole area and those for the granodioritic rocks, in the studied area, could indicate that every rock type has been subjected to different forces, but the complementary of all the forces acting on the studied area has a strike N 28° W. This is consistent with the interpretations of different authors which tend to the fact that the Eastern Desert of Egypt has been subjected to a compressive force of northwesterly direction.Investigation of the tension planes along which mineralization is possible, could reveal that the area is subjected to the first case of stress-strain ellipsoid in which tension fractures are formed at right angle to the greatest strain axis, while shear fractures are formed passing through the intermediate strain axis which make an angle of about 30° with the least strain axis.The structural trend analysis realized four tectonic trends having preferable orientation in the E-W, N-S, NW-SE, and NE-SW directions, of which the E-W is the oldest trend.

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Zusammenfassung Das Untersuchungsgebiet Abu Zawal liegt nördlich der Straße Qena-Safaga, etwa auf halber Strecke. Es ist etwa 250 km² groß und wird aus magmatischen und metamorphen Gesteinen spätpräkambrischen Alters aufgebaut.Das Gebiet wurde geologisch, radiometrisch und strukturgeologisch untersucht im Hinblick auf den Bau der Region und seiner Beziehungen zur Mineralisation und zur Verteilung der Radioaktivität in den verschiedenen Gesteinseinheiten. Entlang radiometrischer Meßprofile wurde jeder Gesteinskomplex statistisch bezüglich seines radioaktiven Untergrundes charakterisiert. Mit bestimmten statistischen Vergleichstests könnten sich Beziehungen zwischen den Gesteinstypen des Gebietes von Abu Zawal und entsprechenden anderer untersuchter Gebiete feststellen lassen.Die geringste Radioaktivität wurde in den basischen metavulkanischen Gesteinen beobachtet, die höchsten Werte dagegen in den spätorogenen Plutoniten. Die Granodiorite besitzen mittlere Radioaktivität. Die Untersuchung hat ergeben, daß die spätorogenen Plutonite des Gebietes von Abu Zawal jünger sein könnten als die entsprechenden Gesteine im Norden der Eastern Desert.Die Untersuchung der beiden konjugierten Schersysteme des gesamten Gebietes wie der granodioritischen Gesteine zeigt, daß jeder Gesteinstyp zwar verschiedenen Kräftefeldern ausgesetzt war, daß aber das Komplement aller Kräfte, die auf das Untersuchungsgebiet wirkten, die Streichrichtung N 28° W (i.e. 152°) besitzt. Dieses stimmt mit den Interpretationen verschiedener Autoren überein, die in der Eastern Desert Ägyptens ein Gebiet sehen, daß einer Kompression aus nordwestlicher Richtung ausgesetzt war.Die Untersuchung von Zerrungsklüften, in denen Mineralisation erfolgen kann, ließ erkennen, daß das Gebiet dem ersten Fall des Strain-Stress-Ellipsoids ausgesetzt war, bei dem die Zerrungsbrüche senkrecht zur Achse der größten Druckspannung erfolgt sind. Die Scherbrüche sind dagegen entlang der Achse der mittleren Druckspannung entstanden, die einen Winkel von ca. 30° mit der Achse des geringsten Druckes bildet.Die strukturelle Analyse ließ vier tektonische Trends erkennen mit den Hauptrichtungen E-W, N-S, NW-SE und NE-SW, von denen die EW-Richtung die älteste ist.

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Résumé La région d'Abu Zawal est située approximativement à mi-chemin au nord de la route Qena-Safage, et couvre environ 250 km². Elle est formée par une série de roches ignées et métamorphiques d'âge précambrien supérieur. - Elle a été étudiée du point de vue gé ologique, radiométrique et structural en vue de reconnaître sa position structurale et sa relation avec les tendances minéralisatrices, ainsi que la répartition de la radioactivité dans les différentes unités. Chaque unité a donc été caractérisée statistiquement par un certain fond radiométrique à l'aide de traverses radiométriques. En outre l'application de certains tests d'inférence statistique a pu trouver les relations pouvant exister entre les différents types de roches de la région d'Abu Zawal et leurs correspondants dans d'autres régions étudiées.La radioactivité la plus faible a été trouvée associée aux roches métavolcaniques basiques, tandis que les valeurs les plus élevées sont liées aux plutonites orogéniques tardives et aux roches qui leur sont associées; quant aux granodiorites, elles représentent un niveau de radioactivité modéré. - L'étude a révélé que les plutonites orogéniques tardives de la région d'Abu Zawal pourraient être plus jeunes que leurs correspondantes du Nord du Désert oriental.L'investigation des deux systèmes conjugués de joints de tension pour l'entièreté de l'étendue et de ceux relatifs aux roches granodioritiques dans l'étendue étudiée, pourrait indiquer que chaque type de roche a été soumis à des forces différentes, mais que le complémentaire de toutes ces forces ayant agi sur la région étudiée a une direction N 28° O. Ceci est en accord avec les interprétations des différents auteurs qui tendent à dire que le Désert oriental de l'Egypte a été soumis à une compression de direction nord-ouest. L'investigation des plans de tension le long desquels la minéralisation est possible pourrait révéler que la région est soumise au premier cas de l'ellipsoïde strain-stress dans lequel les fractures de tension sont à angle droit de l'axe maximum des efforts, tandis que les fractures de cisaillement se forment le long de l'axe intermédiaire des forces qui fait un angle d'environ 30° avec l'axe des efforts minimum.L'analyse structurale des directions a permis de reconnaître 4 directions tectoniques dont l'orientation dominante est E - O, N - S, NO - SE et NE - SO, parmi lesquelles la direction E - O est la plus ancienne.

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Inverted Barrovian Metamorphic Zones in the Poly-Deformed Domains of the Western Wadi Allaqi Shear Zone (South Eastern Desert,Egypt): Geochemical and Structural Constraints

Geotectonics - Poly-deformed late-Proterozoic metamorphic domains covering Um Ashira area at the western segment of Wadi Allaqi shear zone, South Eastern Desert of Egypt, show evidences of inverted...