Comparison of different phases of bismuth silicate nanofibers for photodegradation of organic dyes

Two different phases of bismuth silicate nanofibers [Bi₂SiO₅ and Bi₄(SiO₄)₃] were synthesized using electrospinning technique. BS nanofibers were tested for the photocatalytic degradation of methyl orange and safranin O dyes. Different phases of BS affect the photodegradation efficiency of nanofibers. Impressive enhancement in photocatalytic efficiency and BET surface area of Bi₄(SiO₄)₃ was observed over Bi₂SiO₅. A speedy reduction in dyes concentration was attributed to the rapid formation of oxygenated radicals by the capture of electrons and holes, generated in the BS nanofiber by UV irradiation. Therefore, the photocatalytic mechanism was elucidated using impedance spectroscopy at room temperature. The lower impedance value of Bi₄(SiO₄)₃ nanofibers had improved high-efficiency charge transfer capability. The cycling efficiency (30 times) and recovery characteristics pointed out that Bi₄(SiO₄)₃ nanofibers photocatalysts had high constancy, resilience, and regeneration ability.     

Relation entre les épaisseurs réduites de l'Ozone atmosphérique et sa concentration au niveau du sol

Résumé L'enregistrement continu de la concentration de l'ozone au sol, comparé jour par jour aux valeurs de l'épaisseur réduite de l'ozone total n'a montré aucune corrélation significative entre les deux grandeurs. Une corrélation négative a été constatée entre la quantité d'ozone au sol et le nÒmbre des cas d'inversion dans les couches basses de l'atmosphère. Les variations saisonnières sont cependant analogues, mais l'ozone au sol montre un autre minimum très net au mois de juin, lorsque l'air vient en direction de l'agglomération parisienne.

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Summary The continuous measurements of ozone concentration near ground level when compared with the daily values of total atmospheric ozone did not show any correlation what so ever. The quantity of ozone near the ground, however seems to have a negative correlation with the number of cases of temperature inversion in the lower atmosphere. The annual variations in the two cases are comparable but the ground level ozone shows another minimum in the month of june when the air at the recording station usually comes from Paris and so, is strongly polluted.

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Ce travail a été effectué au Laboratoire de Physique de l'Atmosphère de l'Université de Paris. Je suis heureux d'exprimer ma profonde gratitude à Monsieur le Professeur E.Vassy pour l'accueil qu'il m'a réservé dans son laboratoire, et surtout à Madame A.Vassy qui m'a particulièrement suivi pendant ces études.     

3D geological modeling of Punjab platform,Middle Indus Basin Pakistan through integration of Wireline logs and seismic data

3D Geological control in an area is a key to success for exploration of hydrocarbon. Any discrepancy in geological control leads towards dry wells and ultimately high economic loss. The aim of this study is to build a 3D subsurface geologic model of Punjab platform, Pakistan by integrating mud logs, wire line logs and seismic data for interpreting the structural trends of pre-tertiary geological formations. For this purpose, wire line and mud logs of eighteen wells and about 1500LKm 2D seismic data of Punjab platform was collected from Directorate General of Petroleum Concession (DGPC) Islamabad, Pakistan. A well correlation profile is developed using Petrel and CorelDraw software to assess the distribution of subsurface geological sequences. Synthetic seismograms were developed and then correlated with seismic stacks to pick the horizons of different formations. Time Contour, velocity contour, depth contour and isopach maps are constructed. These maps were then loaded in Structural Modeling window of Petrel software for final construction of 3D geological model. The proposed model indicates that there is a sub-surface monoclinal trend dipping towards a western side of the study area. Further, an anticline at Cambrian level near Fortabbas-Bijnot area is extending to the East in the neighbouring India. In addition, horst and graben structures are also identified at Cambrian level by seismic data. The proposed model is confirmed by results of earlier data, and it is, therefore, recommended that 3D seismic data should further be acquired to explore the structural and stratigraphic traps of Punjab platform, Pakistan.     

Investigation of high-depth cumulonimbus clouds characteristics after seeding to increase precipitation

Analyzed is the development of three cumulonimbus clouds seeded with the crystallizing reagent in Saudi Arabia. Continuous satellite and radar observations of the clouds were carried out during the five-hour period. Obtained are the data on the dynamics of cumulonimbus clouds and their anvils. The vertical development of cumulonimbus clouds and the increase in the radar reflectivity and amount of precipitation were observed after the seeding. The significant increase in the precipitation was observed in all three cases. The results obtained in the present analysis are in agreement with theoretical concepts of the seeding effects on dynamic properties of clouds and precipitation characteristics. They demonstrate a big potential of seeding for increasing the precipitation falling from cumulonimbus clouds.     

Extracting of prospective groundwater potential zones using remote sensing data,GIS, and a probabilistic approach in Bojnourd basin,NE of Iran

Various groundwater potential zones for the assessment of groundwater availability in the Bojnourd basin have been investigated using remote sensing, GIS, and a probabilistic approach. Five independent groundwater factors, including topography, ground slope, stream density, geology units, lineament density, and a groundwater productivity factor, i.e., springs’ discharge, were applied. Discharge rates of 226 springs over the area were collected, and the probabilistic model was designed by the discharge rates of springs as the dependent variable. For training the probabilistic model, a ratio of 70/30% of springs’ discharge was applied and discharge rates of 151 springs were selected to randomly train the model. The frequency ratio for each factor was calculated, and the groundwater potential zones were extracted by summation of frequency ratio maps. The groundwater potential map was also classified into four classes, viz., “very good” (with a frequency ratio of >6.75), “good” (5.5FR6.75), “moderate” (4.75FR5.5), and “poor” (FR4.75). Then, the model was verified based on a success-rate curve method which resulted in obtaining an accuracy ratio of 75.77%. Finally, sensitivity analysis was applied by a factor removal method in five steps. Results reveal that topography factor has the biggest effect on the groundwater potential map and removing this factor eventuates in the lowest accuracy of the final map (AUC = 63. 73%). The groundwater potential map is fairly affected by removing the lineament density factor with an accuracy of 68.80%. Removing the lineament density factor has the lowest effect on the final map with accuracy of 68.80%.     

Potential ecological risk assessment,enrichment, geoaccumulation,and source identification of metals in the surface sediments of Choghakhor Wetland,Iran

This study reported the first comprehensive research on identification of metal concentrations (Fe, Mg, Mn, Pb, Cd, Cr) in order to provide baseline data for future studies, identify possible sources, determine degree of pollution, and identify potential ecological risks of metals in surface sediments from Iran’s Choghakhor Wetland. The order of metal concentration was as follows: Fe > Mg > Mn > Pb > Cd > Cr, with mean concentrations of 6140.35, 1647.32, 289.03, 1.10, and 0.45 µg/g of dry weight, respectively. These results reveal that Choghakhor Wetland is not heavily polluted compared to other regions. The results of enrichment factor (EF) and geoaccumulation index (I _geo) showed that Fe, Pb, Mg, Cr, and Mn presented low levels of contamination and probably originated from natural sources. On the other hand, the results of EF and I _geo indices suggested that Cd concentrations in sediments of Choghakhor Wetland originated from anthropogenic sources. Based on the results of three sets of sediment quality guidelines, only Cd concentration in sediments of Choghakhor Wetland is a threat for aquatic organisms of Choghakhor Wetland. The results of multivariate analysis such as principal component analysis and cluster analysis showed that Fe–Mn, Cr–Mg, and Pb groups originated from natural sources, while Cd concentrations in sediments of Choghakhor Wetland originated from both natural and anthropogenic sources (mainly chemical fertilizers). To our knowledge, this is the first study about metal concentrations in sediments of Choghakhor Wetland, and because of low levels of these metals, these concentrations can be considered background levels for future investigation.     

Effects of Replacing Fishmeal with Animal By-products Meal Supplementation in Diets on the Growth and Nutrient Utilization of Mangrove Red Snapper

A feeding trial was conducted for 75 d to evaluate the nutritive value of a mixture of animal by-products(MAB) as a possible protein source in diets for juvenile mangrove red snapper,Lutjanus argentimaculatus(mean initial body weight,30 g). Fish were fed one of five isonitrogenous diets(40% crude protein) replacing 0,25%(MAB25),50%(MAB50),75%(MAB75) and 100%(MAB100) of fish meal protein with similar percentages of MAB. The MAB consisted of 25% cow liver meal,20% leather meal,20% meat and bone meal,15% blood meal,10% APC(poultry feather meal),8% poultry manure dried,1.5% choline and 0.5% chromic oxide. After 75 d of feeding,fish fed with diets MAB50,MAB75 and MAB100 exhibited significantly lower growth per-formance than that of fish fed with control and MAB25 diets. The optimum level of MAB was estimated to be 23%. Replacement of fish meal by MAB23% showed the following performance:maximum weight gain,510%;SGR,2.39% and FCE,2.83%. The MAB substitution up to 75% of fish meal protein in diets did not show differences in apparent protein digestibility(83.6% for MAB25,79.2% for MAB50,78.7% for MAB75) compared with control(83.4%),whereas in MAB100 group digestibility(65.3%) was sig-nificantly lower than in other groups. The apparent phosphorus absorption of test diet groups was significantly higher(37.1% for MAB25,28.5% for MAB50,55.6% for MAB75 and 54.5% for MAB100) than that of control(11.2%). The levels of protein and ash in the whole body,carcass and viscera increased as MAB substitution in diets increased,whereas lipids and moisture remained con-sistent among all treatment groups. These results showed that approximately 23% of fish meal protein could be replaced by a mixture of animal by-products for juvenile snapper growing from 30 g to 167 g in 75 d without compromising growth performance and feed efficiency.