Ternary systems of 152Eu(III), bulk bentonite and ethylenediaminetetraacetic acid (EDTA) ([Eu] = 7.9 × 10−10 M; pH = 6.0–7.0) have been studied. Without EDTA, there was slow uptake in a two-stage process, with initial rapid sorption of Eu(III) (96%), followed by slower uptake of a much smaller fraction (3.0% over a period of one month). The reversibility of Eu(III) binding was tested by allowing Eu(III) to sorb to bentonite for 1–322 days. EDTA was added to the pre-equilibrated Eu bentonite systems at 0.01 M, a concentration that was sufficient to suppress sorption in a system where EDTA was present prior to the contact of Eu(III) with bentonite. A fraction of the Eu was released instantaneously (30‒50%), but a significant amount remained bound. With time, the amount of Eu(III) retained by the bentonite reduced, with a slow fraction dissociation rate constant of approximately 4.3 × 10−8 s−1 (values in the range 2.2 × 10−8 – 1.0 × 10−7 s−1) for pre-equilibration times ≥7 days. Eventually, the amount of Eu(III) remaining bound to the bentonite was within error of that when EDTA was present prior to contact (4.5% ± 0.6), although in systems with pre-equilibration times >100 days, full release took up to 500 days. Europium interactions with colloidal bentonitewere also studied, and the dissociation rate constant measured by a resin competition method. For the colloids, more Eu was found in the slowly dissociating fraction (60–70%), but the first-order dissociation rate constant was faster, with an average rate constant of 8.8 × 10−7 s−1 and a range of 7.7 × 10−7–9.5 × 10−7 s−1. For both bulk and colloidal bentonite, although slow dissociation was observed for Eu(III), there was no convincing evidence for ‘irreversible’ binding.
RAGIAB ISSA(1-2021)

: Electrical Impedance Tomography (EIT) is a non invasive imaging technique with widespread applications in medicine and industry. It aims to image the conductivity distribution within an object by making electrical measurements on the surface of the volume. Single frequency electrical impedance tomography offers many positive attributes which are now being exploited clinically, but there are also problems which have been identified. Multi-frequency electrical impedance tomography has been proposed to solve this problem by making impedance measurements over a range of frequencies. The reason for this is that the impedance of biological tissues varies with frequency, and the variations are different from tissue to tissue. It is therefore possible, in principle to make static image (i.e. images of the distribution of frequency dependence of the impedance within the body) by measuring tissue impedance over a range of frequencies. In this paper new method concerning multi-frequency electrical impedance tomography have been developed. In the this new developed method; current density and finite element method have been used for the derivation of the complex sensitivity matrix. The new developed method was applied in some models and acceptable results were found. By using these method it possible to produce improvement and fast image reconstructions.
Amani SOLIMAN(3-2012)

A total of 25 randomly purchased bread samples were analyzed in this study from 25 different bakeries in Tajoura city. Bread in Libya is highly consumed among all socioeconomic groups; it is mainly consumed in breakfast, dinner and school meals. Potassium bromate is the most popular additive used in bakery industry worldwide. Bakeries in the US used Potassium bromate as bread improver since 1914 to increase bread volume and texture and improve bread production. The main aim of this study is to assess the safety of bread by the measurement of residual potassium bromate using a rapid and reliable method and to investigate the level of compliance to the ban fourteen years later. This method is based on the reaction between bromate and iodide in acidic medium to produce iodine (I2). The absorbance of I2 was measured spectrophotometrically at 488nm. The calibration curve was linear (R2=0.9996) over the range 1.0 – 5.0mg/L of potassium bromate. Despite the ban of potassium bromate in Libya since 2005 due to its classification as a potential carcinogen it is still detected in local bread loaves. All samples showed high levels of potassium bromate to be 300 to 1333 more than the permissible level set by the American Food and Drug Administration (FDA) which is highly toxic for consumers and could threaten their health over prolonged regular consumption. A continuous pursuance and implementation of the ban on use of potassium bromate in baking industry in Libya is recommended. arabic 11 English 67
RAGIAB ALI MOKHTAR ISSA(1-2020)