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Salje, Henrik,Lessler, Justin,Maljkovic Berry, Irina,Melendrez, Melanie C.,Endy, Timothy,Kalayanarooj, Siripen,A-Nuegoonpipat, Atchareeya,Chanama, Sumalee,Sangkijporn, Somchai,Klungthong, Chonticha,Th American Association for the Advancement of Scienc 2017 Science Vol.355 No.6331
<P>A fundamental mystery for dengue and other infectious pathogens is how observed patterns of cases relate to actual chains of individual transmission events. These pathways are intimately tied to the mechanisms by which strains interact and compete across spatial scales. Phylogeographic methods have been used to characterize pathogen dispersal at global and regional scales but have yielded few insights into the local spatiotemporal structure of endemic transmission. Using geolocated genotype (800 cases) and serotype (17,291 cases) data, we show that in Bangkok, Thailand, 60% of dengue cases living <200 meters apart come from the same transmission chain, as opposed to 3% of cases separated by 1 to 5 kilometers. At distances <200 meters from a case (encompassing an average of 1300 people in Bangkok), the effective number of chains is 1.7. This number rises by a factor of 7 for each 10-fold increase in the population of the 'enclosed' region. This trend is observed regardless of whether population density or area increases, though increases in density over 7000 people per square kilometer do not lead to additional chains. Within Thailand these chains quickly mix, and by the next dengue season viral lineages are no longer highly spatially structured within the country. In contrast, viral flow to neighboring countries is limited. These findings are consistent with local, density-dependent transmission and implicate densely populated communities as key sources of viral diversity, with home location the focal point of transmission. These findings have important implications for targeted vector control and active surveillance.</P>
Zeferino, R. Sanchez,Pal, U.,Melendrez, R,Flores, M. Barboza Techno-Press 2013 Advances in nano research Vol.1 No.4
In this article, we present the effects of Ag doping and after-growth thermal annealing on the photoluminescence (PL) and thermoluminescence (TL) behaviors of $SnO_2$ nanoparticles. $SnO_2$ nanoparticles of 4-7 nm size range containing different Ag contents were synthesized by hydrothermal process. It has been observed that the after-growth thermal annealing process enhances the crystallite size and stabilizes the TL emissions of $SnO_2$ nanostructures. Incorporated Ag probably occupies the interstitial sites of the $SnO_2$ lattice, affecting drastically their emission behaviors on thermal annealing. Both the TL response and dose-linearity of the $SnO_2$ nanoparticles improve on 1.0% Ag doping, and subsequent thermal annealing. However, a higher Ag content causes the formation of Ag clusters, reducing both the TL and PL responses of the nanoparticles.
J. P. Sanhueza,D. Rojas,J. García,M. F. Melendrez,E. Toledo,F. M. Castro Cerda,C. Montalba,A. F. Jaramillo 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.9
In this study, three martensitic creep-resistant steels with 100, 90, and 70 ppm of boron were investigated. The experimentaldata obtained from isothermal aging and creep test at 650 °C were compared with the results of simulation conductedusing TC-PRISMA software. Tungsten was found to be the rate-controlling element in the coarsening of (Cr, Fe, W)23C6carbides; however, this result differed in terms of boron-containing steel. Several studies indicate that the low solubility ofboron in ferrite promotes boron enrichment in (Cr, Fe, W)23C6 carbide, thereby reducing its coarsening rate. However, thismechanism is not universally agreed upon. In the present study, a comparison between experimental and theoretical resultsrevealed that in boron-containing steels, the coarsening of (Cr, Fe, W)23C6 carbide is controlled probably by boron volumediffusion or by trans-interface diffusion.