Theoretical research on structural, electronic, mechanical, lattice dynamical and thermodynamic properties of layered ternary nitrides Ti(2)AN (A = Si, Ge and Sn)

WOS: 000449621500085First-principles density functional theory (DFT) calculations within generalized gradient approximation (GGA) are carried out to investigate the structural, electronic, mechanical, lattice dynamical and thermodynamic properties of Ti(2)AN (A = Si, Ge and Sn) MAX phases. The optimized geometrical parameters such as lattice constants (a, c) and the internal coordinates have been calculated. Electronic band structure and corresponding density of states (DOS) have been obtained. The analysis of the band structures and density of states have shown that these compounds are electrical conductors. The elastic constants have been ascertained using the stress-strain method. The isotropic elastic moduli, known as bulk modulus (B), shear modulus (G), young's modulus (E), poisson's ratio (nu), vickers hardness (H-nu) and linear compressibility coefficients (alpha) have been studied within framework of the Voigt-Reuss-Hill approximation for ideal polycrystalline Ti(2)AN (A = Si, Ge and Sn) MAX aggregates. Furthermore, the phonon dispersion curves as well as accompanying phonon density of states have been comprehensively computed. And also raman and infrared modes at the G point have been obtained. Within the thermodynamic properties, specific heat capacity, entropy, helmholtz free energy and internal energy changes were analyzed depending on the temperature of Ti(2)AN (A = Si, Ge and Sn) compounds. The obtained results are presented in comparison with present theoretical data for Ti2SiN. This is the first quantitative theoretical study of the electronic properties and other properties for Ti2GeN and Ti2SnN compounds and therefore theoretical results for these compounds need to be verified experimentally. (C) 2018 Elsevier B.V. All rights reserved

The reproducibility of random amplified polymorphic DNA (RAPD) profiles of Streptococcus thermophilus strains with XD9, M13 and OPI-02 MOD primers

We optimized the conditions for generating random amplified polymorphic DNA (RAPD) profiles of Streptococcus thermophilus strains by using the polymerase chain reaction (PCR). Several factors can cause the amplification of false and non reproducible bands in the RAPD profiles. We tested three primers, OPI-02 MOD, M13 and XD9 throughout this study. In addition, we tested different concentrations of primer, DNA template and Taq DNA polymerase. We adjusted the ratio of the primer to DNA template. All the three primers yielded reproducible profiles on several days, under optimized concentrations of components and cycling parameters used. The bands of such profiles probably corresponded to perfect annealing sites amplified with good efficacy or present in multiple copies in the genome. Five months later, repeated experiment generated identical bands. However, extra faint bands were detected with M13 and XD9 primers, possibly, corresponding to nonspecific binding resulting from slight variation in temperature or calibration of the thermocycler. Therefore, OPI-02 MOD was determined as the most reliable primer for reproducible profiles of S. thermophilus strains.Key words: Streptococcus thermophilus, random amplified polymorphic DNA (RAPD), DNA template, Taq DNA polymerase, OPI-02MOD, XD9, M13, optimization, reproducibility

Resurrection of Ornithogalum brevipedicellatum (Asparagaceae) with morphological and molecular data

This study evaluates Ornithogalum brevipedicellatum, which was previously accepted as a synonym of O. oligophyllum, as a separate distinct species and discusses the similarities and differences between O. brevipedicellatum and its related species (O. oligophyllum and O. pamphylicum). Similarities and differences among these species were identified by morphological and molecular studies. The leaf morphology and inflorescence of O. brevipedicellatum and O. pamphylicum are similar to each other, and in terms of these features, they show differences from O. oligophyllum. Some diagnostic characteristics are quite different in O. brevipedicellatum and O. pamphylicum, such as the size of tepals, length of fruiting pedicels and style. Morphological data were supported by the results obtained from molecular studies. According to a dendrogram obtained by molecular studies, O. brevipedicellatum and O. pamphylicum are similar. O. oligophyllum is more closely related to O. pyrenaicum used as an out-group. Additionally, the seeds of O. brevipedicellatum were examined with the use of scanning electron microscopy

Plasma-generated poly(allyl alcohol) antifouling coatings for cellular attachment

Conformal poly(allyl alcohol) (PAA) coatings were grown on a biomedical grade polyurethane scaffold using pulsed plasma polymerization of the allyl alcohol monomer. The creation of a continuous wave polymer primer layer increases the interfacial adhesion and stability of a subsequent pulsed plasma deposited PAA film. The resulting PAA coatings are strongly hydrophilic and stable following 7 days incubation in biological media. Films prepared through this energyefficient, two-step process promote human dermal fibroblast cell culture, while resisting E. coli biofilm formation

Migratory corridors and foraging hotspots: Critical habitats identified for Mediterranean green turtles

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordAim: Levels of sea turtle bycatch in the Mediterranean are thought to be unsustainable. We provide a comprehensive overview of adult green turtle (Chelonia mydas) distribution during nesting, migration and foraging phases, highlighting transitory as well as residential areas of high use to facilitate adequate protection for this long-lived, migratory species. Location: Mediterranean Sea. Methods: Thirty-four females were satellite tracked from breeding grounds in the four countries with major nesting (Cyprus, Turkey, Israel and Syria) for a total of 8521 (mean: 251) tracking days in a collaborative effort to summarize the most comprehensive set of distribution data thus far assembled for this species in the Mediterranean. Results: Ten foraging grounds are identified, with two major hotspots in Libya accounting for >50% of turtles tracked to conclusive endpoints. The coastlines of Egypt and Libya contain high densities of migrating turtles following the nesting season, particularly July-September, and likely also pre-nesting (April-June). A high-use seasonal pelagic corridor running south-west from Turkey and Cyprus to Egypt is also evident, used by >50% of all tracked turtles. Main conclusions: Bycatch levels and mortality rates for the key foraging areas and high-density seasonal pathways identified here are largely unknown and should be investigated as a priority. We recommend that the Gulf of Sirte in Libya be explored as a potential biodiversity hotspot and considered for proposal as a marine protected area (MPA). Green turtle fidelity to nesting beaches, foraging areas and migratory pathways renders them vulnerable to localized threats but enables targeted mitigation measures and protection

Age- and region-specific hepatitis B prevalence in Turkey estimated using generalized linear mixed models: a systematic review

Toy M, Önder FO, Wörmann T, et al. Age- and region-specific hepatitis B prevalence in Turkey estimated using generalized linear mixed models: a systematic review. BMC infectious diseases. 2011;11(1): 337.BACKGROUND: To provide a clear picture of the current hepatitis B situation, the authors performed a systematic review to estimate the age- and region-specific prevalence of chronic hepatitis B (CHB) in Turkey. METHODS: A total of 339 studies with original data on the prevalence of hepatitis B surface antigen (HBsAg) in Turkey and published between 1999 and 2009 were identified through a search of electronic databases, by reviewing citations, and by writing to authors. After a critical assessment, the authors included 129 studies, divided into categories: 'age-specific'; 'region-specific'; and 'specific population group'. To account for the differences among the studies, a generalized linear mixed model was used to estimate the overall prevalence across all age groups and regions. For specific population groups, the authors calculated the weighted mean prevalence. RESULTS: The estimated overall population prevalence was 4.57, 95% confidence interval (CI): 3.58, 5.76, and the estimated total number of CHB cases was about 3.3 million. The outcomes of the age-specific groups varied from 2.84, (95% CI: 2.60, 3.10) for the 0-14-year olds to 6.36 (95% CI: 5.83, 6.90) in the 25-34-year-old group. CONCLUSION: There are large age-group and regional differences in CHB prevalence in Turkey, where CHB remains a serious health problem

Antibacterial activity of traditional medicinal plants used by Haudenosaunee peoples of New York State

<p>Abstract</p> <p>Background</p> <p>The evolution and spread of antibiotic resistance, as well as the evolution of new strains of disease causing agents, is of great concern to the global health community. Our ability to effectively treat disease is dependent on the development of new pharmaceuticals, and one potential source of novel drugs is traditional medicine. This study explores the antibacterial properties of plants used in Haudenosaunee traditional medicine. We tested the hypothesis that extracts from Haudenosaunee medicinal plants used to treat symptoms often caused by bacterial infection would show antibacterial properties in laboratory assays, and that these extracts would be more effective against moderately virulent bacteria than less virulent bacteria.</p> <p>Methods</p> <p>After identification and harvesting, a total of 57 different aqueous extractions were made from 15 plant species. Nine plant species were used in Haudenosaunee medicines and six plant species, of which three are native to the region and three are introduced, were not used in traditional medicine. Antibacterial activity against mostly avirulent (<it>Escherichia coli, Streptococcus lactis</it>) and moderately virulent (<it>Salmonella typhimurium, Staphylococcus aureus</it>) microbes was inferred through replicate disc diffusion assays; and observed and statistically predicted MIC values were determined through replicate serial dilution assays.</p> <p>Results</p> <p>Although there was not complete concordance between the traditional use of Haudenosaunee medicinal plants and antibacterial activity, our data support the hypothesis that the selection and use of these plants to treat disease was not random. In particular, four plant species exhibited antimicrobial properties as expected (<it>Achillea millefolium, Ipomoea pandurata, Hieracium pilosella</it>, and <it>Solidago canadensis</it>), with particularly strong effectiveness against <it>S. typhimurium</it>. In addition, extractions from two of the introduced species (<it>Hesperis matronalis </it>and <it>Rosa multiflora</it>) were effective against this pathogen.</p> <p>Conclusions</p> <p>Our data suggest that further screening of plants used in traditional Haudenosaunee medicine is warranted, and we put forward several species for further investigation of activity against <it>S. typhimurium </it>(<it>A. millefolium, H. matronalis, I. pandurata, H. pilosella, R. multiflora, S. canadensis</it>).</p