Photoluminescence properties of AlN homoepilayers with different orientations

AlN homoepilayers and heteroepilayers were grown on polar c-plane and nonpolar a-plane and m-plane orientations of AlN bulk and sapphire substrates by metal organic chemical vapor deposition. A systematic comparative study of photoluminescence properties of these samples revealed that all AlN homoepilayers c, a and m planes were strain free with an identical band gap of about 6.099 (6.035) eV at 10 (300) K, which is about 42 meV below the band gap of c-plane AlN heteroepilayers grown on sapphire. Also, nonpolar a-plane homoepilayers have the highest emission intensity over all other types of epilayers. We believe that a-plane AlN homoepilayers have the potential to provide orders of magnitude improvement in the performance of new generation deep UV photonic devices

Alu-repeat Polymorphism in the Tissue Plasminogen Activator (T-PA) Gene, Seminal T-PA Concentration, and Male Fertility Impairment: A Case-control Study

Background: Tissue plasminogen activator (t-PA) is a protein involved in the fibrinolytic system that catalyzes the conversion of plasminogen into the active plasmin. The activity of t-PA is controlled by plasminogen activator inhibitor-1. t-PA has crucial functions during spermatogenesis. One polymorphism was reported for t-PA gene, either the presence of a 300-bp Alu-repeat (Alu+) or its absence (Alu−). Objective: The current work aimed at studying the association between Alu polymorphism in the t-PA gene and male infertility. Materials and Methods: Using polymerase chain reaction on genomic DNA isolated from the blood of 79 participants, a region polymorphic for Alu element insertion in t-PA gene was amplified. In addition, total t-PA concentration, plasminogen activator inhibitor-1/t-PA complex concentration, and t-PA activity in seminal plasma were measured by enzyme-linked immunosorbent assay. Results: The results indicate that the percentage of infertile participants (n = 50) who were homozygous for t-PA Alu insertion (Alu+/+), heterozygous Alu+/− or homozygous for t-PA Alu deletion (Alu−/−) did not change significantly (p = 0.43, 0.81, and 0.85, respectively) when compared with the control participants (n = 29). On the other hand, a significant decrease (p = 0.0001) of t-PA total concentration in seminal plasma was observed in the infertile group in comparison with the control group. However, the results indicate that there is no association between the t-PA Alu different genotypes and the total t-PA seminal concentration in the infertile group when compared to the control group (p = 0.63). Conclusion: Data obtained from the current study does not support an association between t-PA Alu polymorphism and t-PA seminal concentration or male infertility. Key words: Alu element, Male infertility, Semen, Spermatogenesis, t-PA