Although eye color is usually modeled as a simple, Mendelian trait, further research and observation has indicated that eye color does not follow the classical paths of inheritance. Eye color phenotypes demonstrate both epistasis and incomplete dominance. Although there are about 16 different genes responsible for eye color, it is mostly attributed to two adjacent genes on chromosome 15, hect domain and RCC1-like domain-containing protein 2 (HERC2) and ocular albinism (that is, oculocutaneous albinism II (OCA2)). An intron in HERC2 contains the promoter region for OCA2, affecting its expression. Therefore, singlenucleotide polymorphisms in either of these two genes have a large role in the eye color of an individual. Furthermore, with all genetic expression, aberration also occurs. Some individuals may express two phenotypes-one in each eye-or a complete lack of pigmentation, ocular albinism. In addition, the evolutionary and population roles of the different expressions are significant.

Recently, magnesium has been investigated as a promising bioresorbable orthopedic biomaterial. Its mechanical properties are very similar to natural bone, making it appropriate for load-bearing orthopedic fracture repair applications. However, significant hurdles remain regarding the design of practical implants and methods to control degradation and enhance biocompatibility. Although attempts have been made to hinder magnesium's rapid corrosion via alloying and coating, these studies have used solid monoliths. In an effort to reduce the amount of alloy used for implantation in a shape that mimics cortical bone shape, this study used a thin sheet of Mg AZ31 which was rolled into hollow cylindrical scaffolds. The scaffold was coated with different amounts of Ca-P; this implant demonstrated slowed corrosion in simulated body fluid (SBF) as well as enhanced biocompatibility for mesenchymal stem cells (MSC). In vivo implantation of magnesium alloy scaffold adjacent to the rat femur showed significant biointegration with further deposition of complex Mg-Ca phosphates/carbonates typical of natural bone. Finally, the implant was placed in a critical-size ulna defect in live rabbits, which lead to radiographic union and partial restoration of biomechanical strength in the defect. This study demonstrated that a thin sheet of coated Mg alloy that was spirally wrapped wound be a promising orthopedic biomaterial for bone repair.

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The principal objective of this work was to evaluate the effect of chemical composition and cooling rate on the notch toughness of the heat-affected-zone of welded micro-alloy (HSLA) steel plate. Limited work was carried out on the effect of stress relieving heat treatment on notch toughness. Specimens were prepared by making submerged arc welds over a range of heat inputs on HSLA steel plates containing various amounts of niobium, vanadium and molybdenum. The notch toughness of the heat-affected-zone was measured on precracked specimens as a function of temperature by the instrumented Charpy impact test. Tests recorded the initiation of fracture in terms of load and time over a temperature range that covered the transition from ductile to brittle fracture. Because toughness is related to microstructure, the heat-affected-zone microstructures of specimens were identified. To help in evaluating the microstructures, continuous cooling transformation diagrams were established for all steel compositions. The results indicate that for submerged arc welding, cooling times between 800 and 500 °C of 40 seconds or less do not give rise to toughness-related problems in the heat-affected-zone of single pass welds in typical micro-alloy steels. In this range of cooling rates, toughness increases with increasing rate. The associated microstructural characteristics are fine prior austenite grain size leading to small bainite colony size and an absence of coarse lath boundary carbides or martensite/austenite particles. In practice, a cooling time of 40 seconds corresponds approximately to a heat input of 2.4 kJ/mm in a 12-mm plate or more than 8 kJ/mm in a 50-mm plate. Higher heat inputs result in cooling times of more than 40 seconds. The heat-affected-zone toughness suffers, and at the same time precipitated micro alloy carbides and nitrides are detectable in the microstructure. Loss of toughness in niobium-containing steels stress relieved after welding appears to be particularly serious.