Kyungpook National University

About: Kyungpook National University is a education organization based out in Daegu, South Korea. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 20497 authors who have published 42107 publications receiving 834608 citations.

Worldwide haplotype diversity and coding sequence variation at human bitter taste receptor loci.

Abstract: Bitter taste perception in humans is mediated by receptors encoded by 25 genes that together comprise the TAS2R (or T2R) gene family. The ability to identify the ligand(s) for each of these receptors is dependent on understanding allelic variation in TAS2R genes, which may have a significant effect on ligand recognition. To investigate the extent of coding variation among TAS2R alleles, we performed a comprehensive evaluation of sequence and haplotype variation in the human bitter taste receptor gene repertoire. We found that these genes exhibit substantial coding sequence diversity. In a worldwide population sample of 55 individuals, we found an average of 4.2 variant amino acid positions per gene. In aggregate, the 24 genes analyzed here, along with the phenylthiocarbamide (PTC) receptor gene analyzed previously, specify 151 different protein coding haplotypes. Analyses of the ratio of synonymous and nonsynonymous nucleotide substitutions using the Ka/Ks ratio revealed an excess of amino acid substitutions relative to most other genes examined to date (Ka/Ks 50.94). In addition, comparisons with more than 1,500 other genes revealed that levels of diversity in the TAS2R genes were significantly greater than expected (p 50.11%; po0.01), as were levels of differentiation among continental populations (FST 50.22; po0.05). These diversity patterns indicate that unusually high levels of allelic variation are found within TAS2R loci and that human populations differ appreciably with respect to TAS2R allele frequencies. Diversity in the TAS2R genes may be accounted for by natural selection, which may have favored alleles responsive to toxic, bitter compounds found in plants. These findings are consistent with the view that different alleles of the TAS2R genes encode receptors that recognize different ligands, and suggest that the haplotypes we have identified will be important in studies of receptor-ligand recognition. Hum Mutat 26(3), 199–204, 2005. r 2005 Wiley-Liss, Inc.

Biochar-induced changes in soil properties affected immobilization/mobilization of metals/metalloids in contaminated soils

Abstract: Remediation of metal contaminated soil with biochar is attracting extensive interest in recent years. Understanding the significance of variable biochar properties and soil types helps elucidating the meticulous roles of biochar in immobilizing/mobilizing metals/metalloids in contaminated soils. Six biochars were produced from widely available agricultural wastes (i.e., soybean stover, peanut shells and pine needles) at two pyrolysis temperatures of 300 and 700 °C, respectively. The Pb-, Cu-, and Sb-contaminated shooting range soils and Pb-, Zn-, and As-contaminated agricultural soils were amended with the produced biochars. The mobility of metals/metalloids was assessed by the standard batch leaching test, principal component analysis and speciation modeling. The changes in soil properties were correlated to feedstock types and pyrolysis temperatures of biochars based on the principal component analysis. Biochars produced at 300 °C were more efficient in decreasing Pb and Cu mobility (>93 %) in alkaline shooting range soil via surface complexation with carboxyl groups and Fe-/Al-minerals of biochars as well as metal-phosphates precipitation. By contrast, biochars produced at 700 °C outperformed their counterparts in decreasing Pb and Zn mobility (100 %) in acidic agricultural soil by metal-hydroxides precipitation due to biochar-induced pH increase. However, Sb and As mobility in both soils was unfavorably increased by biochar amendment, possibly due to the enhanced electrostatic repulsion and competition with phosphate. It is noteworthy that the application of biochars is not equally effective in immobilizing metals or mobilizing metalloids in different soils. We should apply biochar to multi-metal contaminated soil with great caution and tailor biochar production for achieving desired outcome and avoiding adverse impact on soil ecosystem.

Ultrasmooth, extremely deformable and shape recoverable Ag nanowire embedded transparent electrode

Abstract: Transparent electrodes have been widely used in electronic devices such as solar cells, displays, and touch screens Highly flexible transparent electrodes are especially desired for the development of next generation flexible electronic devices Although indium tin oxide (ITO) is the most commonly used material for the fabrication of transparent electrodes, its brittleness and growing cost limit its utility for flexible electronic devices Therefore, the need for new transparent conductive materials with superior mechanical properties is clear and urgent Ag nanowire (AgNW) has been attracting increasing attention because of its effective combination of electrical and optical properties However, it still suffers from several drawbacks, including large surface roughness, instability against oxidation and moisture, and poor adhesion to substrates These issues need to be addressed before wide spread use of metallic NW as transparent electrodes can be realized In this study, we demonstrated the fabrication of a flexible transparent electrode with superior mechanical, electrical and optical properties by embedding a AgNW film into a transparent polymer matrix This technique can produce electrodes with an ultrasmooth and extremely deformable transparent electrode that have sheet resistance and transmittance comparable to those of an ITO electrode