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: Population & Catalysis. The organization has 24124 authors who have published 45054 publications receiving 819356 citations. The organization is also known as: Busan National University & Pusan University.

Macrophage Inhibitory Cytokine-1 Induces the Invasiveness of Gastric Cancer Cells by Up-Regulating the Urokinase-type Plasminogen Activator System

Abstract: In our search for genes associated with gastric cancer progression, we identified macrophage inhibitory cytokine-1 (MIC-1), a member of the transforming growth factor β superfamily, as an overexpressed gene in gastric tumor tissues. Expression analysis of MIC-1 in gastric tumor tissues revealed a specific expression in gastric cancer cells, and this expression level was well correlated with invasive potential in various human gastric cancer cell lines. Stable transfection of MIC-1 into SNU-216, a human gastric cancer cell line, significantly increased its invasiveness. The overexpression of MIC-1 into SNU-216 cells significantly increased the activity of urokinase-type plasminogen activator (uPA), and the expressions of uPA and urokinase-type plasminogen activator receptor (uPAR). Similarly, the stimulation of gastric cancer cell lines with purified recombinant MIC-1 dose-dependently increased cell invasiveness, uPA activity, and uPA and uPAR expression. However, MIC-1 did not significantly suppress the proliferation of gastric cancer cell lines. We also found that the stimulation of human gastric cell lines with recombinant MIC-1 strongly induced activation of mitogen-activated protein kinase kinase-1/2 and extracellular signal-regulated kinase-1/2. Additional analysis revealed that PD98059, a selective inhibitor of mitogen-activated protein kinase kinase-1/2, suppressed not only gastric cancer cell invasiveness and uPA activity, but also the mRNA expressions of uPA and uPAR, as induced by recombinant MIC-1. Our results indicate that MIC-1 may contribute to the malignant progression of gastric cancer cells by inducing tumor cell invasion through the up-regulation of the uPA activation system via extracellular signal-regulated kinase-1/2-dependent pathway.

Atmospheric Pressure Plasma Jet Composed of Three Electrodes: Application to Tooth Bleaching

Abstract: Three-electrode plasma jet system consisting of a perforated dielectric tube with two outer and one floating inner electrodes was developed and employed for tooth bleaching. Lowered gas breakdown voltage and increased discharge current were achieved by using the floating inner electrode. Optical emission spectra analysis showed that the rotational temperature of the second positive nitrogen bands was ≈290 K and vibrational temperature was ≈2 500 K, which means this plasma is in highly non-quilibrium state and nonthermal. The presence of excited He, N2, N and O in the plasma plume was revealed. The plasma jet was used in combination with hydrogen peroxide (H2O2) to remove stains from extracted teeth stained by either coffee or red wine. Combining the plasma jet and H2O2 improved the bleaching efficacy by a factor of 3.1 (coffee) and 3.7 (red wine) compared with using H2O2 alone.

Evolutionary biogeography-based whale optimization methods with communication structure: Towards measuring the balance

Abstract: Whale Optimization Algorithm (WOA) is a popular swarm-based algorithm with some spotted defects in its generated patterns during the searching phases. In this study, an enhanced WOA-based method is proposed in order to overcome the drawbacks of slow convergence speed and easy falling of WOA into the local optimum. The designed variant is called enhanced WOA (EWOA), which combines two strategies at the same time. First, a new communication mechanism (CM) is embedded into the basic WOA to promote the global optimal search ability and the exploitation tendency of the WOA. Then, the Biogeography-based Optimization (BBO) algorithm is partially utilized to harmonize the exploration and exploitation trends. A representative set of comprehensive benchmark cases and three engineering cases are utilized to verify the advantages of the proposed EWOA. The experimental results show that the exploration ability, exploitation ability, state of the balance, and convergence style of the algorithm has been improved significantly. Based on results, the proposed EWOA is a promising and excellent algorithm, and it has achieved better solution quality and faster convergence rate compared with other most advanced algorithms. For access to material and guide for users of this paper, we host an online page at https://aliasgharheidari.com .

An Investigation of the Initial Voluntary Environmental Disclosures Made in Korean Semi-Annual Financial Reports

Abstract: In 1997, a group of Korean companies listed on the Korean Stock Exchange disclosed environmental information in their 1997 semi-annual financial reports, which was the first incidence of corporate social and environmental disclosure made in financial reports in Korea. The purpose of this study is to examine these initial environmental disclosures in terms of their quality and quantity and to test for possible relationships between the propensity to disclose and a variety of corporate characteristics. Content analysis is conducted to evaluate the overall standards of disclosure and then a variety of association tests are performed to determine whether the propensity to disclose is associated with selected corporate characteristics. Using a sample of disclosing and non-disclosing firms, I find that industry type and firm size are significantly associated with the propensity to disclose. When the analysis is confined within the discloser group only, financial leverage emerges as a significant explanatory variable for the level of disclosure especially in high-profile industries.

Direct observation of dijets in central Au+Au collisions at sNN=200GeV

Abstract: The STAR Collaboration at the Relativistic Heavy Ion Collider reports measurements of azimuthal correlations of high transverse momentum (p(T)) charged hadrons in Au+Au collisions at higher p(T) than reported previously. As p(T) is increased, a narrow, back-to-back peak emerges above the decreasing background, providing a clear dijet signal for all collision centralities studied. Using these correlations, we perform a systematic study of dijet production and suppression in nuclear collisions, providing new constraints on the mechanisms underlying partonic energy loss in dense matter.