Arsenic content in drinking water and in scalp hair of the arsenic affected areas in Bangladesh were measured using energy dispersive X-ray fluorescence (EDXRF) to determine the contribution of drinking water to body burden and health risks. Around 61% of the water analyzed from tube-wells has arsenic content above 0.05 mg/l and about 13% have arsenic content above 0.01 mg/l. The mean concentration of arsenic in contaminated water is about 0.26 mg/l with the maximum level of 0.83 mg/l. The contaminated water thus contributes a significant amount to the arsenic budget in humans in Bangladesh and consequently, to their health hazards. The average concentration of arsenic in hair of a patient group drinking contaminated water is 14.1 mg/kg where the normal levels are <3.0 mg/kg. The distribution of arsenic in water and in hair is compared and discussed with the data reported in the literature. The daily dietary intake value of arsenic by the adult population in Bangladesh is estimated and assessed signifying health effects.
An immobilized layer-by-layer TiO2/Chitosan (CS) biopolymer onto glass plate has been fabricated, optimized and applied for the removal of 10 mg L−1 phenol and its intermediates under a 45-W fluorescent lamp with a UV leakage irradiance of 4.4 Wm−2. A simple dip-coating technique using the dip-coating solution containing TiO2, epoxidized natural rubber (ENR50) and phenol–formaldehyde resin (PF) was used to immobilize TiO2 onto the CS sub-layer. However, the CS sub-layer did not improve the adsorption of phenol while photodegradation of ENR50 and PF binders acted as macro-pores forming agent within the surface of the TiO2 layer. The degradation kinetics of phenol fitted the pseudo-first order rate model and the main intermediates were qualitatively and quantitatively identified by HPLC analysis to be maleic acid, fumaric acid, hydroquinone and catechol. These intermediates and end-products of the degraded phenol by both TiO2 single layer and layer-by-layer TiO2/CS systems were identical. The total removal of phenol and its intermediates can be achieved within 120 min of irradiation by using layer-by-layer TiO2/CS system, while the same results can be obtained within 360 min of irradiation by using TiO2 single layer.
A new method is introduced to estimate uranium(VI) spectrophotometrically by extraction of its ferron (7-iodo-8-hydroxyquinoline-5-sulfonic
acid) complex with 1% tridodecylamine in chloroform at pH 4.5. The optimum absorption wavelength is 380 nm. The stoichiometry
of the uranium-ferron complex as indicated by a mole ratio plot is 1:2 and its dissociation constant is 3.24·10−9. The effects of various parameters on the absorption are studied. This method has a sensitivity of 0.028 ppm on Sandell's
scale. Interferences are described.
Hydrated antimony pentoxide (HAP) as an absorbent for column operation has been prepared by hydrolysis of SbCl5 with deionized water. Sorption behavior of Sn, Cd, Sb and In was studied on HAP in HCl medium. Radiochemical separation of no-carrier added113mIn from113Sn/125Sb and115mIn from115Cd wa achieved over a HAPO column. The separated products were of high radionuclidic purity.
We study the hyperspace K0(X) of non-empty compact subsets of a Smyth-complete quasi-metric space (X, d). We show that K0(X), equipped with the Hausdorff quasi-pseudometric Hd forms a (sequentially) Yoneda-complete space. Moreover, if d is a T1 quasi-metric, then the hyperspace is algebraic, and the set of all finite subsets forms a base for it. Finally, we prove
that K0(X), Hd) is Smyth-complete if (X, d) is Smyth-complete and all compact subsets of X are d−1-precompact.
Four commercial Saudi Arabian crude oils were characterized by thermogravimetry (TG) and differential thermal analysis (DTA).
These crude oils, Arab Berri (AB), Arab Light (AL), Arab Medium (AM) and Arab Heavy (AH), were also subjected to the traditionally
employed true boiling point (TBP) distillation and simulated distillation (SIMDIST). The TG/DTA data show that the hydrocarbons
present in these crude oils fall into four groups: the volatiles, the low molecular weight, the medium molecular weight and
the high molecular weight compounds. These four types of hydrocarbons were observed to display certain trends, such that the
volatile and low molecular weight hydrocarbons increased, while the medium and high molecular weight hydrocarbons decreased
with the lightness of the crude. The volatile contents of AB, AL, AM and AH crude oils up to 280�C were 50.1, 42.2, 42.3 and
38.5 mass percent, respectively. This confirms that AB is the lightest of these crude oils with maximum volatile content.
The mass percentage loss from the TG results is in good agreement with the percentage distilled from TBP (ASTM D 2892) and
SIMDIST. During evaporation, the TG mass loss follows a similar trend to those of the TBP and SIMDIST results and thus behaves
like distillation. During the oxidative degradation, the TG curve shows a higher mass loss as compared to the distillation
data. The higher deviation of the TG mass loss and percentage distilled at the higher-temperature end of the curve may be
attributed to the higher content of asphaltenes and carbonaceous material present in AH as compared to the AB crude oil. At
around 200�C, the TG mass loss curve intersects the TBP and SIMDIST curves and shows a derivation from distillation behaviour.
This intersection temperature of the TG and distillation curves is observed to decrease with the heaviness of the crude and
can be an indication of the onset of thermal degradation of hydrocarbons present in the crude oil. On the whole, the TG data
closely resemble the distillation results.
Synergic extraction of hydrolyzable lanthanides Dy(III) and Sm(III) has been studied in the low pH range with 0.3M (HTTA-TBA) in chloroform from aqueous perchlorate media. The synergic coefficient was calculated at different pH's and was found maximum at pH 3 for both elements. The composition of the adduct was established as M(TTA)3.3TBA at pH 3. However, a mixture of the adduct of the type M(TTA)3.TBA was proposed at pH 5.9. The possible reaction mechanism at both pHs is discussed, the stability constant
formation constants Km,o and Km,n have been calculated.
Water stress is a severe limitation for crop growth especially in arid and semi-arid regions of the world, as it has a vital role in plant growth and development at all growth stages. The aim of the present study was to evaluate the differential responses of twelve sunflower genotypes to three levels of water supply and select the most suitable one for such conditions. Two field experiments were conducted under adequate (7140 m3/ha), moderate (4760 m3/ha) and severe (2380 m3/ha) water regimes to evaluate the chlorophyll index, transpiration rate, leaf water content, plant height, head diameter, seeds/head, 1000-seed weight, seed and oil yield of the genotypes. Moderate and severe levels of drought had a significant impact on the transpiration rate, leaf water content, yield-contributing characters and oil yield of all the sunflower genotypes. However, the sunflower genotypes showed different responses to the different water regimes. The highest seed and oil yields were attained in L990 and Giza 102 in the case of adequate water supplies, while L38 was the best under moderate and severe drought conditions. On the basis of the results, sunflower genotype L990 could be recommended for growing when adequate water supplies are available, and L38 under moderate and severe water regimes to obtain high seed and oil yields.