Abstract: It is known that the absorption of heavy metals by organisms does not depend only on the total metal concentration in the solution. The concentration of free metal ion, in most cases, is a key factor in predicting the bioavailability of heavy metal. In this paper the results of the chemical speciation of Pb in the water of Modrac Lake are presented. Modrac lake is an artificial lake formed for the purposes of providing drinking water and water for industry. The water of the lake is extremely vulnerable, because it is the main recipient of wastewater from the nearby coal mine as well as municipal wastewater. Samples were analysed using differential pulse anodic stripping voltammetry (DPASV). The samples were taken from four typical areas of lake through the four seasons. The samples from the depth of 2.5 m, and from each location two samples were taken. Complexing capacity and stability constant were calculated.

Abstract: Wettability is the intermolecular interaction of a liquid on a solid resulting in adhesion of the liquid to the solid. These interactions are important for the study of different processes involving the flow of liquids on surfaces or in porous media. The most widely used technique to determine the degree of wettability on a solid surface is the measure of contact angle, which can vary from zero (totally wettable) to 180º (not wettable). One of the ways of modifying the capacity of liquids to wet the solid is by adding surfactants, which are amphiphilic molecules that have double affinity for polar and nonpolar media. This study investigated the wettability of stainless steel 304 in aqueous solutions of KCl and ethoxylated nonionic surfactants ranging from 3 to 100 ethoxylations. In order to observe the influence of roughness on wettability, the stainless steel plate was machined with different sandpapers varying from 100 to 1200 grit. The results showed that polishing the plate decreases wettability. Surfactant solutions exhibit better wettability in stainless steel than the KCl solutions tested. Another fact observed is that a reduction in ethoxylation reduces the contact angle.

Abstract: Microwave absorbing properties of La0.67Ba0.33Mn1-xTixO3 (x = 0, 0.02, 0.04, and 0.06) have been studied in the frequency range 8 – 12 GHz. In this study, La0.67Ba0.33Mn1-xTixO3 (x = 0, 0.02, 0.04, and 0.06) were prepared by solid state reaction method as microwave absorbing material. The crystal structure and magnetic properties were characterized by XRD and permagraph. Refinement results showed that samples are single phase with monoclinic crystal structure. And hysteresis loops results showed that the La0.67Ba0.33Mn1-xTixO3 (x = 0, 0.02, 0.04, and 0.06) samples are soft magnetic materials. Microwave absorption properties were investigated in the frequency range 8 – 12 GHz using vector network analyzer. An optimal reflection loss of -13.26 dB is reached at 11.46 GHz when x = 0.02.

Abstract: The issues to substitute Tin-Lead Solders revolves around the health and environmental hazards of lead, and also legislative actions around the world, so the research community attempt to replace solder alloys for the traditional Sn-Pb alloys As traditional industry lead has been used in soldering materials for electronic applications and it has low melting point and soft, malleable nature, when combined with tin at the eutectic composition gives an alloy which flows easily in the liquid state and solidifies over a very small range of temperature. One of the potentially candidate to replace tin-lead solder is Sn-Zn eutectic alloy it has lower melting temperature. Consequently, it is of interest to determine what reactions can occur in ternary systems derived from the Sn-Zn eutectic. One such system is Cu-Sn-Zn.The specimen was analyzed by Shimadzu XRD. The results show that the increasing of Zinc content will increase the melting temperature. Increasing the content of Zn on Sn-Cu alloys will decease Cu3Sn intermetallic coumpound.