Kangwon National University

About: Kangwon National University is a education organization based out in Chuncheon, South Korea. It is known for research contribution in the topics: Population & Catalysis. The organization has 9836 authors who have published 20002 publications receiving 393562 citations. The organization is also known as: KNU.

Acid-activated biochar increased sulfamethazine retention in soils

Abstract: Sulfamethazine (SMZ) is an ionizable and highly mobile antibiotic which is frequently found in soil and water environments. We investigated the sorption of SMZ onto soils amended with biochars (BCs) at varying pH and contact time. Invasive plants were pyrolyzed at 700 °C and were further activated with 30 % sulfuric (SBBC) and oxalic (OBBC) acids. The sorption rate of SMZ onto SBBC and OBBC was pronouncedly pH dependent and was decreased significantly when the values of soil pH increased from 3 to 5. Modeled effective sorption coefficients (K D,eff) values indicated excellent sorption on SBBC-treated loamy sand and sandy loam soils for 229 and 183 L/kg, respectively. On the other hand, the low sorption values were determined for OBBC- and BBC700-treated loamy sand and sandy loam soils. Kinetic modeling demonstrated that the pseudo second order model was the best followed by intra-particle diffusion and the Elovich model, indicating that multiple processes govern SMZ sorption. These findings were also supported by sorption edge experiments based on BC characteristics. Chemisorption onto protonated and ligand containing functional groups of the BC surface, and diffusion in macro-, meso-, and micro-pores of the acid-activated BCs are the proposed mechanisms of SMZ retention in soils. Calculated and experimental q e (amount adsorbed per kg of the adsorbent at equilibrium) values were well fitted to the pseudo second order model, and the predicted maximum equilibrium concentration of SBBC for loamy sand soils was 182 mg/kg. Overall, SBBC represents a suitable soil amendment because of its high sorption rate of SMZ in soils.

The Involvement of β-Amyrin 28-Oxidase (CYP716A52v2) in Oleanane-Type Ginsenoside Biosynthesis in Panax ginseng

Abstract: Panax species are the most popular medicinal herbs. The root of these plants contains pharmacologically active triterpene saponins, also known as ginsenosides, compounds that are divided into dammarane- and oleanane-type triterpenes. Two CYP716A subfamily genes (CYP716A47 and CYP716A53v2) were recently characterized, encoding an enzyme catalyzing the hydroxylation of dammarane-type triterpenes in Panax ginseng. Herein, we report that one CYP716A subfamily gene (CYP716A52v2) isolated from P. ginseng encodes a β-amyrin 28-oxidase, which is suggested to modify β-amyrin into oleanolic acid, a precursor of an oleanane-type saponin (mainly ginsenoside Ro) in P. ginseng. The ectopic expression of both PNY1 and CYP716A52v2 in recombinant yeast resulted in erythrodiol and oleanolic acid production, respectively. In vitro enzymatic activity assays biochemically confirmed that CYP716A52v2 catalyzed the oxidation of β-amyrin to produce oleanolic acid, and the chemical structure of the oleanolic acid product was confirmed using gas chromatography-mass spectrometry (GC/MS). Transgenic P. ginseng plants were generated via Agrobacterium tumefaciens-mediated transformation: the overexpression of CYP716A52v2 greatly increased the content of oleanane-type ginsenoside (ginsenoside Ro), whereas RNA interference against CYP716A52v2 markedly reduced it. Furthermore, the levels of other dammarene-type ginsenosides were not affected in these transgenic lines. These results indicate that CYP716A52v2 is a β-amyrin 28-oxidase that plays a key role in the biosynthesis of oleanane-type triterpenes in P. ginseng.

Search for narrow resonances using the dijet mass spectrum in pp collisions at √s=8 TeV

Abstract: Results are presented of a search for the production of new particles decaying to pairs of partons (quarks, antiquarks, or gluons), in the dijet mass spectrum in proton-proton collisions at sqrt(s) = 8 TeV. The data sample corresponds to an integrated luminosity of 4.0 inverse femtobarns, collected with the CMS detector at the LHC in 2012. No significant evidence for narrow resonance production is observed. Upper limits are set at the 95% confidence level on the production cross section of hypothetical new particles decaying to quark-quark, quark-gluon, or gluon-gluon final states. These limits are then translated into lower limits on the masses of new resonances in specific scenarios of physics beyond the standard model. The limits reach up to 4.8 TeV, depending on the model, and extend previous exclusions from similar searches performed at lower collision energies. For the first time mass limits are set for the Randall-Sundrum graviton model in the dijet channel.