Concentrically loaded slender square hollow and composite columns incorporating high strength properties

This paper presents an experimental investigation of longitudinally slender box sections (HS) having compact and non-compact cross-sections as well as slender composite sections (CB) fabricated from high strength steel (HSS) and high strength concrete (HSC). Fifteen test specimens (HS) and thirty nine test specimens (CB) having width to thickness ratios (b=t) ranging from 15 to 40 and slenderness ratios ranging from 18 to 124 were tested to failure. Finite element modelling (FEM) of the test specimens (HS and CB) was verified with the experimental results for further analysis. The FEM was used to investigate the effects of residual stresses induced from lightly and heavily welded box sections on the member capacity of slender box sections. The column curves of various design specifications pertaining to slender welded box sections were reviewed by the experimental and FEM peak strengths for the purpose of selecting the most appropriate curves for non-compact box sections. Likewise, the column curves pertaining to the slender composite sections were reviewed by the experimental and FEM peak strengths for the purpose of selecting the most appropriate curves for high strength composite columns fabricated from HSS (690 MPa) and HSC (80–130 MPa)

Genetic polymorphisms of fecundity genes in Watish Sudanese desert sheep

Background and Aim: The Watish sheep is a strain of desert sheep of smaller size compared to other desert sheep ecotypes, and there is anecdotal evidence that it is endowed with high litter size. The present study was designed for screening for polymorphisms in the known fecundity genes (bone morphogenetic protein receptor type 1B A<G in exon 6, bone morphogenetic protein 15 (BMP15) (FecXB, FecXG, FecXH, and FecXI) in exon2, growth differentiation factor 9 (GDF9) – G1 in exon1 and G8 in exon2 and PRLG<A in intron2) and their association with litter size in Watish. Materials and Methods: The study involved 156 Watish ewes of 2-6 years of age, along with data on litter size in the first, second, and third parity from Sinnar state and contiguous Blue Nile State. Genomic DNA was isolated and genotyped using polymerase chain reaction-restriction fragment length polymorphism. Allele and genotype frequencies were calculated by direct counting. Chi-square test for goodness of fit was performed for agreement with Hardy-Weinberg expectations and association testing. Results: The results demonstrated that all individuals were non-carriers for the target mutations of FecB, BMP15 (FecXB, FecXH, and FecXI), and GDF9-G8. With regard to the GDF9-G1 gene, the genotypic frequencies were 0.07% (G+) and 0.93% (++), in FecXG gene they were 0.993% (++) and 0.006% (B+), in PRL gene 0.516(++), 0.347(B+), and 0.137(BB). The Chi-square test showed a non-significant association between ewe's type of birth and the detected mutations genotypes. Conclusion: These results preliminarily indicated that GDF9-G1, BMP15 (FecXG), and PRL genes might have had some contribution for improving litter size in Watish Sudanese sheep. However, further studies using larger samples are needed to detect the effects of those mutations on Watish sheep litter size

The surface nanostructures of titanium alloy regulate the proliferation of endothelial cells

To investigate the effect of surface nanostructures on the behaviors of human umbilical vein endothelial cells (HUVECs), surface nanostructured titanium alloy (Ti-3Zr2Sn-3Mo-25Nb, TLM) was fabricated by surface mechanical attrition treatment (SMAT) technique. Field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were employed to characterize the surface nanostructures of the TLM, respectively. The results demonstrated that nano-crystalline structures with several tens of nanometers were formed on the surface of TLM substrates. The HUVECs grown onto the surface nanostructured TLM spread well and expressed more vinculin around the edges of cells. More importantly, HUVECs grown onto the surface nanostructured TLM displayed significantly higher (p &lt; 0.01 or p &lt; 0.05) cell adhesion and viabilities than those of native titanium alloy. HUVECs cultured on the surface nanostructured titanium alloy displayed significantly higher (p &lt; 0.01 or p &lt; 0.05) productions of nitric oxide (NO) and prostacyclin (PGI2) than those of native titanium alloy, respectively. This study provides an alternative for the development of titanium alloy based vascular stents