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Showing papers by "Pusan National University published in 2009"


Journal ArticleDOI

1,696 citations


Journal ArticleDOI
K. Aamodt1, N. Abel2, A. Abrahantes Quintana, A. Acero  +989 moreInstitutions (76)
TL;DR: In this paper, the production of mesons containing strange quarks (KS, φ) and both singly and doubly strange baryons (,, and − + +) are measured at mid-rapidity in pp collisions at √ s = 0.9 TeV with the ALICE experiment at the LHC.

1,176 citations


Journal ArticleDOI
TL;DR: The purpose of this review is to describe the molecular roles of age-related physiological functional declines and the accompanying chronic diseases associated with aging to provide insights into potential interventions that may affect the aging process and reduce age- related diseases, thereby promoting healthy longevity.

1,029 citations


Journal ArticleDOI
B. I. Abelev1, Madan M. Aggarwal2, Zubayer Ahammed3, B. D. Anderson4  +367 moreInstitutions (47)
TL;DR: In this article, the authors measured the charged-particle spectra at the BNL Relativistic Heavy Ion Collider (RHIC) time projection chamber and reported the average transverse momenta, total particle production, particle yield ratios, strangeness, and baryon production rates as a function of collision system and centrality.
Abstract: Identified charged-particle spectra of pi(+/-), K(+/-), p, and (p) over bar at midrapidity (vertical bar y vertical bar < 0.1) measured by the dE/dx method in the STAR (solenoidal tracker at the BNL Relativistic Heavy Ion Collider) time projection chamber are reported for pp and d + Au collisions at root s(NN) = 200 GeV and for Au + Au collisions at 62.4, 130, and 200 GeV. Average transverse momenta, total particle production, particle yield ratios, strangeness, and baryon production rates are investigated as a function of the collision system and centrality. The transverse momentum spectra are found to be flatter for heavy particles than for light particles in all collision systems; the effect is more prominent for more central collisions. The extracted average transverse momentum of each particle species follows a trend determined by the total charged-particle multiplicity density. The Bjorken energy density estimate is at least several GeV/fm(3) for a formation time less than 1 fm/c. A significantly larger net-baryon density and a stronger increase of the net-baryon density with centrality are found in Au + Au collisions at 62.4 GeV than at the two higher energies. Antibaryon production relative to total particle multiplicity is found to be constant over centrality, but increases with the collision energy. Strangeness production relative to total particle multiplicity is similar at the three measured RHIC energies. Relative strangeness production increases quickly with centrality in peripheral Au + Au collisions, to a value about 50% above the pp value, and remains rather constant in more central collisions. Bulk freeze-out properties are extracted from thermal equilibrium model and hydrodynamics-motivated blast-wave model fits to the data. Resonance decays are found to have little effect on the extracted kinetic freeze-out parameters because of the transverse momentum range of our measurements. The extracted chemical freeze-out temperature is constant, independent of collision system or centrality; its value is close to the predicted phase-transition temperature, suggesting that chemical freeze-out happens in the vicinity of hadronization and the chemical freeze-out temperature is universal despite the vastly different initial conditions in the collision systems. The extracted kinetic freeze-out temperature, while similar to the chemical freeze-out temperature in pp, d + Au, and peripheral Au + Au collisions, drops significantly with centrality in Au + Au collisions, whereas the extracted transverse radial flow velocity increases rapidly with centrality. There appears to be a prolonged period of particle elastic scatterings from chemical to kinetic freeze-out in central Au + Au collisions. The bulk properties extracted at chemical and kinetic freeze-out are observed to evolve smoothly over the measured energy range, collision systems, and collision centralities.

784 citations


Journal ArticleDOI
TL;DR: It is demonstrated that dynamic membrane traffic mediates the sequential translocation and assembly of STING, both of which are essential processes required for maximal activation of the innate immune response triggered by dsDNA.
Abstract: Microbial nucleic acids are critical for the induction of innate immune responses, a host defense mechanism against infection by microbes Recent studies have indicated that double-stranded DNA (dsDNA) induces potent innate immune responses via the induction of type I IFN (IFN) and IFN-inducible genes However, the regulatory mechanisms underlying dsDNA-triggered signaling are not fully understood Here we show that the translocation and assembly of the essential signal transducers, stimulator of IFN genes (STING) and TANK-binding kinase 1 (TBK1), are required for dsDNA-triggered innate immune responses After sensing dsDNA, STING moves from the endoplasmic reticulum (ER) to the Golgi apparatus and finally reaches the cytoplasmic punctate structures to assemble with TBK1 The addition of an ER-retention signal to the C terminus of STING dampens its ability to induce antiviral responses We also show that STING co-localizes with the autophagy proteins, microtubule-associated protein 1 light chain 3 (LC3) and autophagy-related gene 9a (Atg9a), after dsDNA stimulation The loss of Atg9a, but not that of another autophagy-related gene (Atg7), greatly enhances the assembly of STING and TBK1 by dsDNA, leading to aberrant activation of the innate immune response Hence Atg9a functions as a regulator of innate immunity following dsDNA stimulation as well as an essential autophagy protein These results demonstrate that dynamic membrane traffic mediates the sequential translocation and assembly of STING, both of which are essential processes required for maximal activation of the innate immune response triggered by dsDNA

690 citations


Journal ArticleDOI
TL;DR: In this paper, the tensile strength, elongation at break (E ), and water vapor permeability (WVP) of control PLA-based composite films with different types of nanoclays, such as Cloisite Na +, Cloisitic 30B and Cloisitesite 20A, were tested using a solvent casting method and their tensile, water vapor barrier and antimicrobial properties were tested.
Abstract: PLA-based composite films with different types of nanoclays, such as Cloisite Na + , Cloisite 30B and Cloisite 20A, were prepared using a solvent casting method and their tensile, water vapor barrier and antimicrobial properties were tested Tensile strength (TS), elongation at break ( E ), and water vapor permeability (WVP) of control PLA film were 5045 ± 075 MPa, 30 ± 01%, and 18 × 10 −11 g m/m 2 s Pa, respectively TS and E of nanocomposite films prepared with 5 g of clay/100 g of PLA decreased 10–20% and 11–17%, respectively, depending on the clays used On the contrary, WVP of the nanocomposite films decreased 6–33% through nanoclay compounding Among the clay types used, Cloisite 20A was the most effective in improving the water vapor barrier property while sacrificing tensile properties the least The effect of clay concentration tested using Cloisite 20A showed a significant decrease in TS and WVP, with increases in clay content Among the PLA/clay composite films tested, only PLA/Cloisite 30B composite film showed a bacteriostatic function against Listeria monocytogenes

579 citations


Journal ArticleDOI
TL;DR: It is found that silver-ion-mediated ROS-generation affected bactericidal activity and silver ions strongly enhanced paraquat-induced oxidative stress, indicating close correlation and synergism between the conventional and ROS-mediated silver toxicity.

501 citations


Journal ArticleDOI
TL;DR: In this article, the effect of nanofluids on convective heat transfer was investigated through a circular straight tube with a constant heat flux condition in the laminar and turbulent flow regime.

474 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigate a three-particle azimuthal correlator which is a P even observable, but directly sensitive to the charge separation effect, and report measurements of charged hadrons near center-of-mass rapidity with this observable in Au+Au and Cu+Cu collisions at s(NN)=200 GeV using the STAR detector.
Abstract: Parity-odd domains, corresponding to nontrivial topological solutions of the QCD vacuum, might be created during relativistic heavy-ion collisions. These domains are predicted to lead to charge separation of quarks along the system's orbital momentum axis. We investigate a three-particle azimuthal correlator which is a P even observable, but directly sensitive to the charge separation effect. We report measurements of charged hadrons near center-of-mass rapidity with this observable in Au+Au and Cu+Cu collisions at s(NN)=200 GeV using the STAR detector. A signal consistent with several expectations from the theory is detected. We discuss possible contributions from other effects that are not related to parity violation.

454 citations


Journal ArticleDOI
TL;DR: Hyperuricemia may modestly increase the risks of both stroke incidence and mortality, and future research is needed to determine whether lowering uric acid level has any beneficial effects on stroke.
Abstract: BACKGROUND Hyperuricemia is hypothesized to be a risk factor for stroke and other cardiovascular disease, but to date results from observational studies are conflicting.

420 citations


Journal ArticleDOI
TL;DR: The authors found that cross-cultural variations in aging perceptions were associated with culture-level indicators of population aging, education levels, values, and national character stereotypes, and these associations were stronger for societal views on aging and perceptions of socioemotional changes than for perceptions of physical and cognitive changes.
Abstract: College students (N=3,435) in 26 cultures reported their perceptions of age-related changes in physical, cognitive, and socioemotional areas of functioning and rated societal views of aging within their culture. There was widespread cross-cultural consensus regarding the expected direction of aging trajectories with (a) perceived declines in societal views of aging, physical attractiveness, the ability to perform everyday tasks, and new learning; (b) perceived increases in wisdom, knowledge, and received respect; and (c) perceived stability in family authority and life satisfaction. Cross-cultural variations in aging perceptions were associated with culture-level indicators of population aging, education levels, values, and national character stereotypes. These associations were stronger for societal views on aging and perceptions of socioemotional changes than for perceptions of physical and cognitive changes. A consideration of culture-level variables also suggested that previously reported differences in aging perceptions between Asian and Western countries may be related to differences in population structure.

Journal ArticleDOI
TL;DR: In this article, a new approach to model surface roughness in fused deposition modeling (FDM) is proposed, which is based on real-world FDM parts and a theoretical model is presented by considering the main factors that crucially affect surface quality.

Journal ArticleDOI
TL;DR: The authors investigated the efficacy of a volatility model for three crude oil markets (Brent, Dubai, and WTI) with regard to its ability to forecast and identify volatility stylized facts, in particular volatility persistence or long memory.

Journal ArticleDOI
TL;DR: The data are the first to demonstrate that the role of miR‐21 in the adipogenic differentiation of hASCs is mediated through the modulation of TGF‐β signaling, which may underlie the development of obesity or other metabolic diseases.
Abstract: A better understanding of the molecular mechanisms that govern human adipose tissue-derived mesenchymal stem cells (hASCs) differentiation could improve hASCs-based cell therapy and provide new insights into a number of diseases, including obesity. In this study, we examined the roles of microRNA-21 (miR-21) in adipogenic differentiation of hASCs. We found that miR-21 expression was transiently increased after induction of adipogenic differentiation, peaked at 3 days, and returned to the baseline level 8 days. Lentiviral overexpression of miR-21 enhanced adipogenic differentiation. Overexpression of miR-21 decreased both protein and mRNA levels of TGFBR2. The expression of TGFBR2 was decreased during adipogenic differentiation of hASCs in concordance with an increase in the level of miR-21. In contrast, inhibiting miR-21 with 2'-O-methyl-antisense microRNA increased TGFBR2 protein levels in hASCs, accompanied by decreased adipogenic differentiation. The activity of a luciferase construct containing the miR-21 target site from the TGFBR2 3'UTR was lower in LV-miR21-infected hASCs than in LV-miLacZ infected cells. TGF-beta-induced inhibition of adipogenic differentiation was significantly decreased in miR-21 overexpressing cells compared with control lentivirus-transduced cells. RNA interference-mediated downregulation of SMAD3, but not of SMAD2, increased adipogenic differentiation. Overexpression and inhibition of miR-21 altered SMAD3 phosphorylation without affecting total levels of SMAD3 protein. Our data are the first to demonstrate that the role of miR-21 in the adipogenic differentiation of hASCs is mediated through the modulation of TGF-beta signaling. This study improves our knowledge of the molecular mechanisms governing hASCs differentiation, which may underlie the development of obesity or other metabolic diseases.

Journal ArticleDOI
TL;DR: In this article, a disc-on-disc type tester was used to examine the role of fullerene nanoparticles dispersed in a mineral oil-based lubricant, and the results showed that the direct effect of nanoparticles was much more dependent on the magnitude of the applied normal load than the surface enhancement effect.
Abstract: A disc-on-disc type tester was used to examine the role of fullerene nanoparticles dispersed in a mineral oil-based lubricant. In the friction test, the friction coefficient of the disc specimen immersed in the nano-oil was significantly lower than that of the disc specimen immersed in the mineral oil. This suggests that the nanoparticles dispersed in mineral oil played the important role in the lubrication enhancement of nano-oil. A series of experiments in this study were carried out to delineate the two effects [i.e., direct effect (e.g., rolling/sliding/filming) and surface enhancement effect (e.g., mending/polishing)] of nanoparticles for nano-oil-based lubrication enhancement. The disc specimens immersed in the nano-oils during the friction test was removed, and then they were re-immersed in new mineral oil for an additional friction test. The direct and surface enhancement effect of nanoparticles was then visualised by the evolution of the friction coefficient of the disc specimen immersed in the mineral- and nano-oil. The results showed that the direct effect of nanoparticles was much more dependent on the magnitude of the applied normal load than the surface enhancement effect.

Journal ArticleDOI
TL;DR: In this paper, a nanocomposites of waterborne polyurethane (WPU) with functionalized graphene sheets (FGS) were prepared by an in situ method.
Abstract: Nanocomposites of waterborne polyurethane (WPU) with functionalized graphene sheets (FGS) were prepared by an in situ method. The morphology observed by transmission electron microscopy showed that pristine nanosize FGS can be finely dispersed in a WPU matrix so that it can efficiently improve the conductivity of WPU. The modulus improvement by the reinforcing effect of FGS was more evident than our previous results of nanocomposites prepared by a physical mixing method, showing that the interactions between FGS and WPU were improved when made by the in situ method. In addition, the FGS enhanced the crystallization of the soft segment of WPU evidently; however, it reduced that of the hard segment. The thermal degradation of WPU was accelerated by FGS.

Journal ArticleDOI
TL;DR: In this article, an innovative structural system with slit dampers was developed, which could not only provide good seismic performance but could also be easily repaired after a heavy earthquake by using a mechanical joint that is equipped with a metallic damper as the beam-to-column connection.

Journal ArticleDOI
TL;DR: Results indicate that the relative disorder strength strongly increases across the superconductor-insulator transition, and superconductivity can be suppressed at both positive and negative gate bias.
Abstract: Caviglia et al. [Nature (London) 456, 624 (2008)] have found that the superconducting LaAlO3/SrTiO3 interface can be gate modulated. A central issue is to determine the principal effect of the applied electric field. Using magnetotransport studies of a gated structure, we find that the mobility variation is almost 5 times that of the sheet carrier density. Furthermore, superconductivity can be suppressed at both positive and negative gate bias. These results indicate that the relative disorder strength strongly increases across the superconductor-insulator transition.

Journal ArticleDOI
TL;DR: In this article, graphite nanoparticles were used to fabricate nano lubricants with enhanced tribological properties and lubrication characteristics, and the results showed that when comparing fixed plates coated with raw and nano-lubricants, the plate coated with a nano lubricant containing graphite nanarticles had a lower friction coefficient and less wear.
Abstract: Many researchers have tried to improve the tribological characteristics of lubricants to decrease friction coefficients and wear rates. One approach is simply the use of additives in the base lubricant to change its properties. Recently, nanoparticles have emerged as a new kind of additive because of their size, shape and other properties. A nano lubricant is a new kind of engineering lubricant made of nanoparticles, dispersant, and base lubricant. In this study, graphite nanoparticles were used to fabricate nano lubricants with enhanced tribological properties and lubrication characteristics. The base lubricant used was industrial gear oil, which has a kinematic viscosity of 220 cSt at 40°C. To investigate the physical and tribological properties of nano lubricants, friction coefficients and temperatures were measured by a disk-on-disk tribotester. The surfaces of the fixed plates were observed by a scanning electron microscope and an atomic force microscope to analyze the characteristics of the friction surfaces. The results show that when comparing fixed plates coated with raw and nano lubricants, the plate coated with a nano lubricant containing graphite nanoparticles had a lower friction coefficient and less wear. These results indicate that graphite nanoparticle additives improve the lubrication properties of regular lubricants.

Journal ArticleDOI
TL;DR: In this article, a polyurethane/functionalized graphene sheet (FGS) was used as a nanofiller in the preparation of polymer nanocomposites, and the results showed that FGS has a high affinity for TPU, and it could therefore be used effectively in preparation of TPU/FGS nanocompositionites without any further chemical surface treatment.
Abstract: BACKGROUND: Functionalized graphene sheet (FGS) was recently introduced as a new nano-sized conductive filler, but little work has yet examined the possibility of using FGS as a nanofiller in the preparation of polymer nanocomposites. In particular, there are currently no published papers that evaluate polyurethane/FGS nanocomposites. The purpose of this study was to prepare a polyurethane/FGS nanocomposite and examine the morphological and physical properties of the material. RESULTS: A cast nanocomposite film was prepared from a mixture of thermoplastic polyurethane (TPU) solution and FGS suspended in methyl ethyl ketone. The FGS dispersed on the nanoscale throughout the TPU matrix and effectively enhanced the conductivity. A nanocomposite containing 2 parts of FGS per 100 parts of TPU had an electrical conductivity of 10−4 S cm−1, a 107 times increase over that of pristine TPU. The dynamic mechanical properties showed that the FGS efficiently reinforced the TPU matrix, particularly in the temperature region above the soft segment melt. CONCLUSION: Our results show that FGS has a high affinity for TPU, and it could therefore be used effectively in the preparation of TPU/FGS nanocomposites without any further chemical surface treatment. This indicates that FGS is an effective and convenient new material that could be used for the modification of polyurethane. It could also be used in place of other nano-sized conductive fillers, such as carbon nanotubes. Copyright © 2009 Society of Chemical Industry

Journal ArticleDOI
TL;DR: In this paper, the authors present a systematic study of high transverse-momentum charged-di-hadron correlations at small azimuthal pair separation Delta phi in d+Au and central Au-Au collisions at s(NN)=200 GeV.
Abstract: The STAR Collaboration at the Relativistic Heavy Ion Collider presents a systematic study of high-transverse-momentum charged-di-hadron correlations at small azimuthal pair separation Delta phi in d+Au and central Au+Au collisions at s(NN)=200 GeV. Significant correlated yield for pairs with large longitudinal separation Delta eta is observed in central Au+Au collisions, in contrast to d+Au collisions. The associated yield distribution in Delta eta x Delta phi can be decomposed into a narrow jet-like peak at small angular separation which has a similar shape to that found in d+Au collisions, and a component that is narrow in Delta phi and depends only weakly on Delta eta, the "ridge." Using two systematically independent determinations of the background normalization and shape, finite ridge yield is found to persist for trigger p(t)>6 GeV/c, indicating that it is correlated with jet production. The transverse-momentum spectrum of hadrons comprising the ridge is found to be similar to that of bulk particle production in the measured range (2 < p(t)< 4 GeV/c).

Journal ArticleDOI
26 Nov 2009-Nature
TL;DR: These results suggest that delta-doped SrTiO3 provides a model system in which to explore the quantum transport and interplay of both superconducting and normal electrons, and demonstrate that high-quality complex oxide heterostructures can maintain electron coherence on the macroscopic scales probed by transport, as well as on the microscopic scales demonstrated previously.
Abstract: Heavily doped semiconductors can exhibit superconductivity, but their performance is severely limited by extremely large electronic disorder. Similarly, the electron mean free path in low-dimensional superconducting thin films is usually limited by interface scattering or atomic-scale disorder. Kozuka et al. use niobium doping to fabricate a high-quality, two-dimensional superconducting layer within a thin-film heterostructure based on the first known superconducting semiconductor, SrTiO3. This should provide a model system in which to explore the quantum transport and interplay of both superconducting and normal electrons.

Journal ArticleDOI
TL;DR: The data indicate that miR‐196a plays a role in hASC osteogenic differentiation and proliferation, which may be mediated through its predicted target, HOXC8.
Abstract: The elucidation of the molecular mechanisms that govern the differentiation and proliferation of human adipose tissue-derived mesenchymal stem cells (hASCs) could improve hASC-based cell therapy. In this study, we examined the roles of microRNA (miRNA)-196a on hASC proliferation and osteogenic differentiation. Lentiviral overexpression of miR-196a decreased hASC proliferation and enhanced osteogenic differentiation, without affecting adipogenic differentiation. Overexpression of miR-196a decreased the protein and mRNA levels of HOXC8, a predicted target of miR-196a. HOXC8 expression was decreased during osteogenic differentiation of hASCs, and this decrease in HOXC8 expression was concomitant with an increase in the level of miR-196a. In contrast, inhibition of miR-196a with 2'-O-methyl-antisense RNA increased the protein levels of HOXC8 in treated hASCs and was accompanied by increased proliferation and decreased osteogenic differentiation. The activity of a luciferase construct containing the miR-196a target site from the HOXC8 3'UTR was lower in LV-miR196a-infected hASCs than in LV-miLacZ-infected cells. RNA interference-mediated downregulation of HOXC8 in hASCs increased their proliferation and decreased their differentiation into osteogenic cells, without affecting their adipogenic differentiation. Our data indicate that miR-196a plays a role in hASC osteogenic differentiation and proliferation, which may be mediated through its predicted target, HOXC8. This study provides us with a better knowledge of the molecular mechanisms that govern hASC differentiation and proliferation.

Journal ArticleDOI
TL;DR: A singular topology was observed around the exceptional point on the eigenfrequency surfaces, resulting in fundamental inconsistency in mode labeling in a chaotic optical microcavity of a large size parameter.
Abstract: We present spectroscopic observation of an exceptional point or the transition point between mode crossing and avoided mode crossing of neighboring quasieigenmodes in a chaotic optical microcavity of a large size parameter. The transition to the avoided mode crossing was impeded until the degree of deformation exceeded a threshold deformation owing to the system's openness also enhanced by the shape deformation. As a result, a singular topology was observed around the exceptional point on the eigenfrequency surfaces, resulting in fundamental inconsistency in mode labeling.

Journal ArticleDOI
TL;DR: Results indicated that DPHC might be a potent inhibitor for alpha-glucosidase and alpha-amylase as well as it delays absorption of dietary carbohydrates.

Journal ArticleDOI
TL;DR: It is shown that the formation of both O vacancies and Zn interstitials becomes significantly enhanced by a strong attractive interaction between them, making these defects an important source of n-type conductivity in ZnO.
Abstract: As the concentration of intrinsic defects becomes sufficiently high in O-deficient ZnO, interactions between defects lead to a significant reduction in their formation energies. We show that the formation of both O vacancies and Zn interstitials becomes significantly enhanced by a strong attractive interaction between them, making these defects an important source of n-type conductivity in ZnO.

Journal ArticleDOI
TL;DR: A bulk heterojunction photocatalyst is highly active for oxidative degradation of isopropyl alcohol and hydrogen production from water under visible light, because the exciton easily reaches the interface and dissociates to minimize recombination.

Journal ArticleDOI
TL;DR: In this paper, the tribological behavior of copper nanoparticles suspended in oil is investigated experimentally, and the average friction coefficient for raw oil and nano-oil with 25 and 60 nanometers was investigated by using a disc-on-disc tribotester.

Journal ArticleDOI
TL;DR: In this article, the authors report the progress of two-photon polymerization based on 3D microfabrication, including the results obtained from the original research, and present three sections: improvement of resolution, precise design schemes, and applications of three-dimensional microstructures.
Abstract: Two-photon stereolithography (TPS) provides many advantages for achieving two-dimensional (2D) and three-dimensional (3D) micrometer-scale polymeric, ceramic and metallic structures applicable to complicated optical and neo-electronic microdevices. In the fabrication of high-resolution 3D microstructures, TPS has significant advantages over conventional microelectromechanical system (MEMS) processing, which involves time-consuming multistep indirect fabrication processes. Many studies have recently been made to develop and improve the TPS process, focusing on creating greater efficiency, higher resolution, and greater productivity, which are essential requirements of a practical TPS process. For the first time, an artistic microstructure has recently been successfully produced with an ultraprecise spatial resolution, sub-30 nm nanofibers, 3D multilayer imprint stamps for mass production, and ceramic 3D microstructures. In this review, we report the progress of two-photon polymerization based on 3D microfabrication, including the results obtained from the original research. This report is presented in three sections: improvement of resolution, precise design schemes, and applications of 3D microstructures.

Journal ArticleDOI
TL;DR: The hepatocyte-specific contrast agent gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) was developed to improve the detection and characterization of focal liver lesions at magnetic resonance (MR) imaging.
Abstract: The clinical applications of Gd-EOB-DTPA–enhanced MR imaging combined with conventional T2-weighted MR cholangiography are reviewed, with emphasis on the potential of this technique to allow morphologic and functional assessment of the biliary system.