On the Fractography of Impact-Tested Samples of Al-Si Alloys for Automotive Alloys

Castings were prepared from both industrial and experimental 319.2, B319.2 and A356.2 alloy melts, containing Fe levels of 0.2–1.0 wt%. Stontium-modified (∼200 ppm) melts were also prepared for each alloy/Fe level. Impact testing of heat-treated samples was carried out using an instrumented Charpy impact testing machine. At low Fe levels and high cooling rates (0.4% Fe, dendrite arm spacing (DAS) of 23 μm), crack initiation and propagation in unmodified 319 alloys occur through the cleavage of β-Al5FeSi platelets (rather than by their decohesion from the matrix). The morphology of the platelets (individual or branched) is important in determining the direction of crack propagation. Cracks also propagate through the fracture of undissolved CuAl2 or other Cu intermetallics, as well as through fragmented Si particles. In Sr-modified 319 alloys, cracks are mostly initiated by the fragmentation or cleavage of perforated β-phase platelets, in addition to that of coarse Si particles and undissolved Cu-intermetallics. In A356.2 alloys, cracks initiate mainly through the fracture of Si particles or their debonding from the Al matrix, while crack propagation occurs through the coalescence of fractured Si particles, except when β-Al5FeSi intermetallics are present, in which case the latter takes precedence. In the Sr-modified case, cracks propagate through the linkage of fractured/debonded Si particles, as well as fragmented β-iron intermetallics. In samples exhibiting low-impact energies, crack initiation and propagation occur mainly through cleavage of the β-iron intermetallics

Novel Panel of Early Diagnostic Markers for Experimental Hepatocellular Carcinoma

Abstract Hepatocellular carcinoma (HCC) accounts for 80% to 90% of primary liver cancer and it is a major health problem worldwide, ranking the fifth most common cancer in the world. In the present study we aimed to explore new or highly pertinent rapid and sensitive markers for early diagnosis of hepatocellular malignant changes. Two groups of rats were used in this study, one served as control, the second as trichloroacetic acid (TCA) challenged group (0.5 g/kg/d for 5 days, sacrificed after 4 weeks). The results showed that TCA group had a significant increase in blood alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase ( ALP), and acetyl CoA synthase (ACAS) activities, total bilirubin, triglycerides, total glycosaminoglycans (TGAGs), parallel with alpha-fetoprotein (AFP). On the other hand, it induced a significant reduction in serum total lipoprotein lipase (TLPL) activity. The histopathological investigations of hepatic tissue confirmed these neoplastic changes induced by TCA. The three parameters (TGAGs level, TLPL and ACAS activities) can be added as new markers for early diagnosis of hepatocellular carcinoma and elevation of the sensitivity and specificity of AFP

Genska karakterizacija, kloniranje i ekspresija Toll-like receptora 1 mRNA nilske tilapije (Oreochromis niloticus)

Toll-like receptors (TLRs) are the most studied group of pathogen recognition receptor categories that detects infectious agents in vertebrates. Fish TLRs exhibit clear, distinct features, structure and a larger diversity than in other vertebrates. This study focused on identifying and detecting the structure of Oreochromis niloticus (Nile tilapia) Toll- like receptor-1 (TLR1|) as a model in freshwater bony fish. The full-length cDNA sequence of Oreochromis niloticus TLR1 mRNA was cloned. Cloning and sequence analysis revealed that the complete cDNA sequence of Oreochromis niloticus TLR1 consists of 2355 base pairs and encodes a polypeptide of 785 amino acids. The molecular analysis of the amino acid sequence indicated that Oreochromis niloticus TLR1 has the standard structural features and major components of amino acids of TLR family members, and is considered an orthologue to the vertebrate TLR1, not a paralogue. The translated amino acid analysis showed 96%, 88%, 85%, and 85% degrees of identity with Zebra Mbuna, Sea bass, Damsel fish, and Clownfish, respectively; and showed 66% identity t with electric eels and 61% with starlets. Phylogenetic analysis revealed that the Nile tilapia TLR1 is closely related to Larimichthys crocea, Epinephelus coioides, and Takifugu rubripes TLR1. Oreochromis niloticus TLR1 was expressed in the kidneys, brain, spleen, intestines, muscle, liver, gills, heart and skin. Quantitative RT-PCR showed differences in the expression levels between the tested tissues. In conclusion, this study is the first report (according to our knowledge) and provides a complete molecular and functional characterization of Oreochromis niloticus toll-like receptor 1, which is considered to be functionally orthologous to TLR1 in other species models.Toll-like receptori (TLR) najviše su istraživana skupina receptora za prepoznavanje uzročnika bolesti u kralježnjaka. TLR u riba pokazuju jasna razlikovna svojstva, strukturu i veliku raznolikost u odnosu na druge kralježnjake. Ovo je istraživanje usredotočeno na identifikaciju i otkrivanje Toll-like receptora 1 (TLR1) u nilske tilapije (Oreochromis niloticus) kao predstavnika slatkovodnih riba. Klonirana je puna sekvencija cDNA TLR1 mRNA. Utvrđeno je da se kompletna sekvencija cDNA TLR1 nilske tilapije sastoji od 2355 baznih parova i kodira polipeptid od 785 aminokiselina. Molekularna analiza sekvencija aminokiselina upućuje na to da TLR1 nilske tilapije ima standardna strukturna svojstva i glavne komponente porodice TLR receptora i smatra se ortologom, ne paralogom TLR1 kralježnjaka. Analiza prevedenih aminokiselina pokazala je stupanj identičnost od 96 % s mbuna zebrom, 88 % s lubinom, 85 % s damsel ribom i 85 % s ribom klaun, dok je stupanj identičnosti s električnom jeguljom bio 66 %, a s ribom starlet 61 %. Filogenetska analiza pokazala je da je TLR1 nilske tilapije usko povezan s TLR1 vrsta Larimichthys crocea, Epinephelus coioides i Takifugu rubripes. TLR1 nilske tilapije bio je izražen u bubrezima, mozgu, slezeni, crijevima, mišiću, jetri, škrgama, srcu i na koži. Kvantitativni RT-PCR pokazao je razlike u razini ekspresije među testiranim tkivima. Prema našim podacima ovo je istraživanje prvo koje donosi kompletnu molekularnu i funkcionalnu karakterizaciju Toll-like receptora 1 nilske tilapije, te se smatra funkcionalnim ortologom TLR1 u drugih vrsta

Effect of kaolin geopolymer ceramic addition on the properties of Sn-3.0Ag-0.5Cu solder joint

This paper investigates the effects of different weight percentages (0, 0.5, 1.0, 1.5 and 2.0 wt.%) of kaolin geopolymer ceramic (KGC) on the microstructure formation, thermal properties, spreadability and joint strength in Sn-3.0Ag-0.5Cu (SAC305) lead-free solder alloys in order to develop a new composite solder system. Advanced characterization techniques such as Electron backscatter diffraction (EBSD) and synchrotron micro-XRF were used to study the behaviors of the pure SAC305 and KGC reinforced SAC305 composite solders. Experimental results shows that the addition of KGC refines the β-Sn area and increases the eutectic area with fine intermetallics formation. In addition, the thickness of the IMC layer is reduced with a reduction in undercooling value for the KGC reinforced SAC305 composite solder. The spreadability of the KGC reinforced SAC305 composite solder is significantly increased in the spreadable area with a higher strength of solder joint. Significantly, the results obtained prove that 1.0 wt.% KGC addition gives better performance in terms of microstructure formation, thermal properties, spreadability and joint strength. Synchrotron micro-XRF interestingly indicated that some Al and Si, which are the major elements in geopolymer systems, migrate into the solder area