Electrochemical and wetting behavior of as-cast Sn-Zn-Sb lead free solders alloys

Ternary alloys SnZn12Sb8, SnZn10Sb10, SnZn8Sb12, SnZn6Sb14, and SnZn2Sb18 were prepared by induction melting. Electrochemical behavior and wetting (contact angle) of prepared as-cast samples were investigated using open circuit potential measurement and sessile drop technique. The results of electrochemical investigation show that open-circuit potential, few seconds after immersing of electrodes, shifts toward more negative values, indicating a relatively smaller rate of dissolution during the spontaneous dissolution process under the curentless conditions. After that period, the values of potential tend to be constant with time. It was found that all investigated alloys have poor wettability on copper substrate and the contact angle values decrease with increasing superheat temperature

Optimization of the aging regime of Al-based alloys

Successful simulation of problems and phenomena related to the changes of the alloys composition is possible by applying simplex plans. The concentration (simplex) triangle application for the design of the optimal regime of Al-5wt%Cu-Pb-Bi alloy aging process is presented in this paper. The iso-lines of the given alloy’s mechanical properties in temperature-aging time coordinates were obtained by applying the mathematical models based of the given aging regimes, and the obtained results of changed properties. Regression polynomial of the fourth degree was used as the mathematical model, whereas the effect of the aging regime has been observed through the changes of tensile strength and contraction. Based on the obtained results, we have come to the conclusion that the simplex lattice method can be successfully applied to a great number of heat treatment aspects when with the increase of the temperature the duration time must be reduced, and vice versa (aging, annealing, homogenizing, etc.)

The microstructure and properties of as-cast Sn-Zn-Bi solder alloys

U radu su prikazani rezultati ispitivanja strukturnih i mehaničkih karakteristika bezolovnih lemnih legura u sistemu kalaj-cink-bizmut. Nakon dobijanja legura u indukcionoj peći sa zaštitnom atmosferom, trostrukim pretapanjem odmerene količine čistih metala, izvršena su ispitivanja strukture tako dobijenih uzoraka legura optičkom i skenirajućom electronskom mikroskopijom (SEM). Energetskom disperzivnom spektroskopijom (EDS) određen je hemijski sastav faza prisutnih u strukturi legura. Izvršena su merenja tvrdoće, i zatezne čvrstoće ispitivanih legura. Sva istraživanja su sprovedena sa ciljem boljeg upoznavanja osobina legura u sistemu Sn-Zn-Bi, koji se smatra odgovarajućom zamenom olovnih lemnih legura.Research on the lead-free solders has attracted wide attention, mostly as the result of the implementation of the Directive on the Restriction of the Use of Hazardous Substances in Electrical and Electronic Equipment. The Sn-Zn solder alloys have been considered to be one of the most attractive lead-free solders due to its ability to easily replace Sn-Pb eutectic alloy without increasing the soldering temperature. Furthermore, the mechanical properties are comparable or even superior to those of Sn-Pb solder. However, other problems still persist. The solution to overcoming these drawbacks is to add a small amount of alloying elements (Bi, Ag, Cr, Cu and Sb) to the Sn-Zn alloys. Microstructure, tensile strength, and hardness of the selected Sn-Zn-Bi ternary alloys have been investigated in this study. The SEM-EDS was used for the identification of co-existing phases in the samples. The specimens' microstructures are composed of three phases: Sn-rich solid solution as the matrix, Bi-phase and Zn-rich phase. The Bi precipitates are formed around the Sn-dendrit grains as well as around the Zn-rich phase. The amount of Bi segregation increases with the increase of Bi content. The Sn-Zn-Bi alloys exhibit the high tensile strength and hardness, but the values of these mechanical properties decrease with the increase of Bi content, as well as the reduction of Zn content. The results presented in this paper may offer further knowledge of the effects various parameters have on the properties of lead-free Sn-Zn-Bi solders

The microstructure and properties of as-cast Sn-Zn-Bi solder alloys

Research on the lead-free solders has attracted wide attention, mostly as the result of the implementation of the Directive on the Restriction of the Use of Hazardous Substances in Electrical and Electronic Equipment. The Sn-Zn solder alloys have been considered to be one of the most attractive lead-free solders due to its ability to easily replace Sn-Pb eutectic alloy without increasing the soldering temperature. Furthermore, the mechanical properties are comparable or even superior to those of Sn-Pb solder. However, other problems still persist. The solution to overcoming these drawbacks is to add a small amount of alloying elements (Bi, Ag, Cr, Cu, and Sb) to the Sn-Zn alloys. Microstructure, tensile strength, and hardness of the selected Sn-Zn-Bi ternary alloys have been investigated in this study. The SEM-EDS was used for the identification of co-existing phases in the samples. The specimens’ microstructures are composed of three phases: Sn-rich solid solution as the matrix, Bi-phase and Zn-rich phase. The Bi precipitates are formed around the Sn-dendrit grains as well as around the Zn-rich phase. The amount of Bi segregation increases with the increase of Bi content. The Sn-Zn-Bi alloys exhibit the high tensile strength and hardness, but the values of these mechanical properties decrease with the increase of Bi content, as well as the reduction of Zn content. The results presented in this paper may offer further knowledge of the effects various parameters have on the properties of lead-free Sn-Zn-Bi solders

Anticancer Properties of Ganoderma Lucidum Methanol Extracts In Vitro and In Vivo

Anticancer activities of various extracts of the medicinal mushroom, Ganoderma lucidum, have been widely demonstrated and are mainly associated with the presence of different bioactive polysaccharides and triterpenoids. We have evaluated and compared in vitro and in vivo the antitumor effects of two preparations from Ganoderma lucidum: a methanol extract containing total terpenoids (GLme) and a purified methanol extract containing mainly acidic terpenoids (GLpme). Both extracts inhibited tumor growth of B16 mouse melanoma cells inoculated subcutaneously into syngeneic C57BL/6 mice and reduced viability of B16 cells in vitro, whereby GLme exhibited stronger effect. Furthermore, anticancer activity of GLme was demonstrated for the first time against two other rodent tumor cell lines, L929-mouse fibrosarcoma and C6-rat astrocytoma. The mechanism of antitumor activity of GLme comprised inhibition of cell proliferation and induction of caspase-dependent apoptotic cell death mediated by upregulated p53 and inhibited Bcl-2 expression. Moreover, the antitumor effect of the GLme was associated with intensified production of reactive oxygen species, whereas their neutralization by the antioxidant, N-acetyl cysteine, resulted in partial recovery of cell viability. Thus, our results suggest that GLme might be a good candidate for treatment of diverse forms of cancers.Serbian Ministry of Science [143029, 143016

Anti-tumor effect of Coriolus versicolor methanol extract against mouse B16 melanoma cells: In vitro and in vivo study

Numerous studies have shown immunostimulatory and anti-tumor effects of water and standardized aqueous ethanol extracts derived from the medicinal mushroom, Coriolus versicolor, but the biological activity of methanol extracts has not been examined so far. In the present study we investigated the anti-tumor effect of C versicolor methanol extract (which contains terpenoids and poly-phenols) on B16 mouse melanoma cells both in vitro and in vivo. In vitro treatment of the cells with the methanol extract (25-1600 mu g/ml) reduced melanoma cell viability in it dose-dependent manner. Furthermore, in the presence of the methanol extract (200 mu g/ml, concentration IC50) the proliferation of B16 cells was arrested in the G(0)/G(1) phase of the cell cycle, followed by both apoptotic and secondary necrotic cell death. In vivo methanol extract treatment (i.p. 50 mg/kg, for 14 days) inhibited tumor growth in C57BL/6 mice inoculated with syngeneic B16 tumor cells. Moreover, peritoneal macrophages collected 21 days after tumor implantation from methanol extract-treated animals exerted stronger tumoristatic activity ex vivo than macrophages from control melanoma-bearing rnice. Taken together, our results demonstrate that C. versicolor methanol extract exerts pronounced anti-melanoma activity, both directly through antiproliferative and cytotoxic effects on tumor cells and indirectly through promotion of macrophage anti-tumor activity. (c) 2008 Elsevier Ltd. All rights reserved.nul

Anti-tumor effect of Coriolus versicolor methanol extract against mouse B16 melanoma cells: In vitro and in vivo study

Numerous studies have shown immunostimulatory and anti-tumor effects of water and standardized aqueous ethanol extracts derived from the medicinal mushroom, Coriolus versicolor, but the biological activity of methanol extracts has not been examined so far. In the present study we investigated the anti-tumor effect of C versicolor methanol extract (which contains terpenoids and poly-phenols) on B16 mouse melanoma cells both in vitro and in vivo. In vitro treatment of the cells with the methanol extract (25-1600 mu g/ml) reduced melanoma cell viability in it dose-dependent manner. Furthermore, in the presence of the methanol extract (200 mu g/ml, concentration IC50) the proliferation of B16 cells was arrested in the G(0)/G(1) phase of the cell cycle, followed by both apoptotic and secondary necrotic cell death. In vivo methanol extract treatment (i.p. 50 mg/kg, for 14 days) inhibited tumor growth in C57BL/6 mice inoculated with syngeneic B16 tumor cells. Moreover, peritoneal macrophages collected 21 days after tumor implantation from methanol extract-treated animals exerted stronger tumoristatic activity ex vivo than macrophages from control melanoma-bearing rnice. Taken together, our results demonstrate that C. versicolor methanol extract exerts pronounced anti-melanoma activity, both directly through antiproliferative and cytotoxic effects on tumor cells and indirectly through promotion of macrophage anti-tumor activity. (c) 2008 Elsevier Ltd. All rights reserved.nul

The antitumor properties of a nontoxic, nitric oxide-modified version of saquinavir are independent of Akt

Application of the HIV protease inhibitor saquinavir (Saq) to cancer chemotherapy is limited by its numerous side effects. To overcome this toxicity, we modified the original compound by covalently attaching a nitric oxide (NO) group. We compared the efficacy of the parental and NO-modified drugs in vitro and in vivo. The novel compound saquinavir-NO (Saq-NO) significantly reduced the viability of a wide spectrum of human and rodent tumor cell lines at significantly lower concentration than the unmodified drug. In contrast to Saq, Saq-NO had no effect on the viability of primary cells and drastically reduced B16 melanoma growth in syngeneic C57BL/6 mice. In addition, at the equivalent of the 100% lethal dose of Saq, Saq-NO treatment caused no apparent signs of toxicity. Saq-NO blocked the proliferation of C6 and 1316 cells, up-regulated p53 expression, and promoted the differentiation of these two cell types into oligodendrocytes or Schwann-like cells, respectively. Although it has been well documented that Saq decreases tumor cell viability by inhibiting Akt, the anticancer properties of Saq-NO were completely independent of the phosphatidylinositol 3-kinase/Akt signaling pathway. Moreover, Saq-NO transiently up-regulated Akt phosphorylation, delivering a protective signal that could be relevant for primary cell protection and the absence of drug toxicity in vivo. It was unlikely that released NO was independently responsible for these drug effects because Saq-NO treatment increased intracellular and secreted NO levels only slightly. Rather, the chemical modification seems to have produced a qualitatively new chemical entity, which may have a unique mode of action against cancer cells. [Mol Cancer Ther 2009;8(5):1169-78]Serbian Ministry of Science [143029]; University of Catani