Pusan National University

About: Pusan National University is a education organization based out in Busan, South Korea. It is known for research contribution in the topics: Catalysis & Population. The organization has 24124 authors who have published 45054 publications receiving 819356 citations. The organization is also known as: Busan National University & Pusan University.

Chemical nature of ferroelastic twin domains in CH3NH3PbI3 perovskite.

Abstract: The extraordinary optoelectronic performance of hybrid organic–inorganic perovskites has resulted in extensive efforts to unravel their properties. Recently, observations of ferroic twin domains in methylammonium lead triiodide drew significant attention as a possible explanation for the current–voltage hysteretic behaviour in these materials. However, the properties of the twin domains, their local chemistry and the chemical impact on optoelectronic performance remain unclear. Here, using multimodal chemical and functional imaging methods, we unveil the mechanical origin of the twin domain contrast observed with piezoresponse force microscopy in methylammonium lead triiodide. By combining experimental results with first principles simulations we reveal an inherent coupling between ferroelastic twin domains and chemical segregation. These results reveal an interplay of ferroic properties and chemical segregation on the optoelectronic performance of hybrid organic–inorganic perovskites, and offer an exploratory path to improving functional devices. Combined multimodal atomic force microscopy, ion microscopy, ion mass spectrometry and infrared spectrometry experiments explore the chemical properties of ferroelastic twin domains in hybrid lead halide perovskites.

p53‐independent Induction of p21 (WAF1/CIP1), Reduction of Cyclin B1 and G2/M Arrest by the Isoflavone Genistein in Human Prostate Carcinoma Cells

Abstract: Genistein, a natural isoflavonoid phytoestrogen, is a strong inhibitor of protein tyrosine kinase and DNA topoisomerase II activities. Genistein has been shown to have anticancer proliferation, differentiation and chemopreventive effects. In the present study, we have addressed the mechanism of action by which genistein suppressed the proliferation of p53-null human prostate carcinoma cells. Genistein significantly inhibited the cell growth, which effect was reversible, and induced dendrite-like structure. The inhibitory effects of genistein on cell growth proliferation were associated with a G2/M arrest in cell cycle progression concomitant with a marked inhibition of cyclin B1 and an induction of Cdk inhibitor p21 (WAF1/CIP1) in a p53-independent manner. Following genistein treatment of cells, an increased binding of p21 with Cdk2 and Cdc2 paralleled a significant decrease in Cdc2 and Cdk2 kinase activity with no change in Cdk2 and Cdc2 expression. Genistein also induced the activation of a p21 promoter reporter construct, utilizing a sequence distinct from the p53-binding site. Analysis of deletion constructs of the p21 promoter indicated that the response to genistein could be localized to the 300 base pairs proximal to the transcription start site. These data suggest that genistein may exert a strong anticarcinogenic effect, and that this effect possibly involves an induction of p21, which inhibits the threshold kinase activities of Cdks and associated cyclins, leading to a G2/M arrest in the cell cycle progression.

Measurement of charm production at central rapidity in proton-proton collisions at √s = 2.76 TeV

Abstract: The p t-differential production cross sections of the prompt (B feed-down subtracted) charmed mesons D0, D+, and D*+ in the rapidity range |y| < 0.5, and for transverse momentum 1 < p t < 12 GeV/c, were measured in proton-proton collisions at $ \sqrt {s} = 2.76\;{\text{TeV}} $ with the ALICE detector at the Large Hadron Collider. The analysis exploited the hadronic decays D0 → K−π+, D+ → K−π+π+, D*+ → D0π+, and their charge conjugates, and was performed on a $ {\mathcal{L}_{{{\rm int} }}} = 1.1\;{\text{n}}{{\text{b}}^{{ - 1}}} $ event sample collected in 2011 with a minimum-bias trigger. The total charm production cross section at $ \sqrt {s} = 2.76\;{\text{TeV}} $ and at 7 TeV was evaluated by extrapolating to the full phase space the p t-differential production cross sections at $ \sqrt {s} = 2.76\;{\text{TeV}} $ and our previous measurements at $ \sqrt {s} = 7\;{\text{TeV}} $ . The results were compared to existing measurements and to perturbative-QCD calculations. The fraction of $ {\text{c}}\overline {\text{d}} $ D mesons produced in a vector state was also determined.