Jungsoo Kim

Stromal Cell Derived Factor‐1 (SDF‐1) Targeting Reperfusion Reduces Myocardial Infarction in Isolated Rat Hearts

Recent studies have shown that stromal cell derived factor-1 (SDF-1), first known as a cytokine involved in recruiting stem cells into injured organs, confers myocardial protection in myocardial infarction, which is not dependent on stem cell recruitment but related with modulation of ischemia-reperfusion (I/R) injury. However, the effect of SDF has been studied only in a preischemic exposure model, which is not clinically relevant if SDF is to be used as a therapeutic agent. Our study was aimed at evaluating whether or not SDF-1 confers cardioprotection during the reperfusion period. Hearts from SD rats were isolated and perfused with the Langendorff system. Proximal left coronary artery ligation, reperfusion, and SDF perfusion in KH buffer was done according to study protocol. Area of necrosis (AN) relative to area at risk (AR) was the primary endpoint of the study. Significant reduction of AN/AR by SDF in an almost dose-dependent manner was noted during both the preischemic exposure and reperfusion periods. In particular, infusion of a high concentration of SDF (25 nM/L) resulted in a dramatic reduction of infarct size, which was greater than that achieved with ischemic pre- or postconditioning. SDF perfusion during reperfusion was associated with a similar significant reduction of infarct size as preischemic SDF exposure. Further studies are warranted to assess the potential of SDF as a therapeutic agent for reducing I/R injury in clinical practice.

Effect of hot pressing/melt mixing on the properties of thermoplastic polyurethane

In-depth understanding of the influence of hot pressing and melt processing on the properties of thermoplastic polyurethane (TPU) is critical for effective mechanical recycling of TPU scraps. Therefore, this study focused on the effects of hot pressing and melt mixing on molecular weight (MW), polydispersity index (PDI), melt index (MI), characteristic IR peaks, hardness, thermal degradation and mechanical properties of TPU. The original TPU pellet (o-TPU) showed two broad peaks at lower and higher MW regions. However, four TPU film samples, TPU-0 prepared only by hot pressing of o-TPU pellet and TPU-1, TPU-2 and TPU-3 obtained by hot pressing of melt mixed TPUs (where the numbers indicate the run number of melt mixing), exhibited only a single peak at higher MW region. The TPU-0 film sample had the highest Mn and the lowest PDI and hardness. The TPU-1 film sample had the highest Mw and tensile modulus. As the run number of melt mixing increased, the peak-intensity of hydrogen bonded C=O stretching increased, however, the free C=O peak intensity, tensile strength/elongation at break and average MW decreased. All the samples showed two stage degradations. The degradation temperatures of TPU-0 sample (359 °C and 394 °C) were higher than those of o-TPU (342 °C and 391 °C). While all the melt mixed samples degraded at almost the same temperature (365 °C and 381 °C). The first round of hot pressing and melt mixing was found to be the critical condition which led to the significant changes ofMn/Mw/PDI, MI, mechanical property and thermal degradation of TPU.

Indexing moving objects on road networks in p2p and broadcasting environments

Scalability is one of the crucial problems in realizing massively distributed systems such as ubiquitous computing. In this paper, we focus on indexing methods in massively distributed environments. A number of work on indexing in P2P, like CAN and Chord, have been devoted to overcome this problem. The lengths of routing path are O(dn1/d for CAN and O(log n) for Chord, which are in fact the cost of search, where there are n nodes. In this paper, we propose an alternative indexing scheme not only relying on P2P but also on broadcasting environments. The contributions of this paper include firstly the reduction of routing path to nearly O(1) for road-oriented query by using broadcasting, and secondly handling the mobility of nodes on road networks.

Effect of Extractant on the Color Characteristics of Natural Colorant Extracts

Natural colorant extracts were obtained by extraction from tumeric root, gardenia seeds, mugwort and green tea using water, methanol, ethanol and acetone as extractants at room temperature for 3 hours under shaking condition(180rpm) with liquor ratio(solid:solvent; 1:100). The main pigment components of tumeric root, gardenia seeds, mugwort and green tea are known to be curcumin, crocin, chlorophyll b and epigallocatechin gallate, respectively. The effects of the kind of extractant and pH on the color characteristics of natural colorant extracts were investigated. The solubility parameters of pigment components were determined to find adequate extractant. The solubility parameters of curcumin, crocin, chlorophyll b and epigallocatechin gallate were found to be 27.85, 29.40, 19.48 and . As expected, solvents that have a solubility parameter similar to that of pigment component were generally found to be effective to obtain pigment extracts having high visible absorbance(A). The extract(pigment/solvent) with high visible absorbance was generally found to have low (lightness) and high Chroma(, purity).

Melt Grafting of Citraconic Acid onto an Ethylene-Propylene-Diene Terpolymer (EPDM) -Effect of Reaction Conditions and Initiator Type on the Melt Grafting of Citraconic Acid onto EPDM-

Melt grafting of citraconic acid (CCA) onto an ethylene-propylene-diene terpolymer (EPDM) with various peroxide initiators was performed using a Haake Rheocorder. Finding the optimum running condition and concentration is critical for effective grafting and performance of grafted material. Therefore, this study focused on the effects of mixing (reaction) condition and monomer/initiator dosages on the grafting degree, grafting efficiency and crosslinking degree (gel content), melt flow index and mechanical properties of CCA-g-EPDM. As the grafting degree/crosslinking degrees increased, the tensile strength increased significantly, but elongation at break and melt flow index decreased. The initiator 2,5-dimethyl-2,5-di(tert-butyl peroxy)-hexane (T-101) appeared to meet for the best grafting(2.31%). The grafting degree increased markedly with increasing monomer CCA/initiator T-101 contents. The grafting degree also increased with increasing mixing temperature/time, and then leveled off or decreased/increased a little. The optimum monomer/initiator dosages and reaction temperature/time were found to be about 5/0.05 wt% and 180 °C/15min, respectively. 요 약:Haake Rheocorder로 각종 과산화물 개시제를 사용하여 ethylene-propylene-diene terpolymer (EPDM) 에 단량체 citraconic acid (CCA)을 용융 그라프트 중합을 하여 그라프트 중합물 CCA-g-EPDM을 얻었으며, 이 때 효율적인 그라프트 정도와 우수한 성능을 지닌 그라프트 중합물을 얻기 위해서 최적의 반응조건과 최적의 단량체/개 시제 농도를 찾는 것은 매우 중요하다. 따라서 본 연구에서는 반응조건과 단량체 및 개시제 함량이 CCA-g-EPDM의 그라프트 정도, 그라프트 효율, 가교정도 (겔화도), 용융흐름지수(MI) 및 기계적 물성 등에 미치는 영향에 초점을 맞추었다. 그라프트 정도와 가교도가 증가함에 따라서 인장강도는 상당히 증가한 반면, 파괴신도 및 MI는 감소하였다. 개시제 중에서 2,5-dimethyl-2,5-di(tert-butyl peroxy)-hexane (T-101)가 가장 우수한 그라프트 정도 (2.31 %)를 나타내었으며, CCA와 T-101의 함량이 증가함에 따라 그라프트 정도가 크게 증가하였다. 그리고 그라프트 정도는 반응(혼합)온도 및 반응시간이 증가함에 따라 역시 증가하다가 어느 온도/시간 이상에서는 안정화 혹은 약간 감소하는 경향을 나타내었다. 이러한 영향으로 결과로부터 최적의 단량체/개시제 농도는 5/0.05 wt%이었으며, 최적 의 반응온도/시간은 180 C/15분인 것을 알 수 있었다.

Vorinostat-eluting poly(DL-lactide-co-glycolide) nanofiber-coated stent for inhibition of cholangiocarcinoma cells

Purpose The aim of this study was to fabricate a vorinostat (Zolinza™)-eluting nanofiber membrane-coated gastrointestinal (GI) stent and to study its antitumor activity against cholangiocarcinoma (CCA) cells in vitro and in vivo. Methods Vorinostat and poly(DL-lactide-co-glycolide) dissolved in an organic solvent was sprayed onto a GI stent to make a nanofiber-coated stent using an electro-spinning machine. Intact vorinostat and vorinostat released from nanofibers was used to assess anticancer activity in vitro against various CCA cells. The antitumor activity of the vorinostat-eluting nanofiber membrane-coated stent was evaluated using HuCC-T1 bearing mice. Results A vorinostat-incorporated polymer nanofiber membrane was formed on the surface of the GI stent. Vorinostat was continuously released from the nanofiber membrane over 10 days, and its release rate was higher in cell culture media than in phosphate-buffered saline. Released vorinostat showed similar anticancer activity against various CCA cells in vitro compared to that of vorinostat. Like vorinostat, vorinostat released from nanofibers induced acetylation of histone H4 and inhibited histone deacetylases 1⋅3⋅4/5/7 expression in vitro and in vivo. Furthermore, vorinostat nanofibers showed a higher tumor growth inhibition rate in HuCC-T1 bearing mice than vorinostat injections. Conclusion Vorinostat-eluting nanofiber membranes showed significant antitumor activity against CCA cells in vitro and in vivo. We suggest the vorinostat nanofiber-coated stent may be a promising candidate for CCA treatment.

Thermal / Electrical Conductivities of Graphites Treated in Aqueous NaOH Solution

Thermal and electrical conductivities of the natural, artificial, and expandable graphites were analyzed after treatment in NaOH aqueous solution. In order to investigate the elimination of the oxidized groups and impurities on the graphite surfaces after NaOH treatment, the graphite samples were structurally characterized by using XRD, XPS, Raman, FE-SEM. The thermal and electrical conductivities of the graphite samples were significantly improved after NaOH treatment. These results were caused by the structural rehabiliation.

Deodorizing Performance and Antibacterial Properties of Fabric Treated with Pomegranate and Gallnut Extracts Compared with Properties of Commercial Deodorizing and Antibacterial Agents

We compared the ability of pomegranate and gallnut extracts to protect fabrics against odors and bacteria with the deodorizing and antibacterial efficacy of two commer- cial deodorizing and antibacterial agents. Cotton, silk, or wool fabric was treated with pomegranate extract, gallnut extract, or one of two commercial deodorizing and antibac- terial agents, F or D. The fabrics were tested for their ability to withstand the odor of ammo- nia, trimethylamine, acetaldehyde, or acetic acid, and their antibacterial activity against Klebsiella pneumonia and Staphylococcus aureus. We analyzed the volatile components in pomegranate extract, gallnut extract, F, and D using gas chromatography-mass spectrom- etry. We found more acidic volatile components in the pomegranate and gallnut extracts than in F and D. In contrast, there were more cyclo compounds in the volatile materials of F and D than in the pomegranate or gallnut extracts. The fabrics treated with pomegranate or gallnut extract showed a greater ability to withstand odors than those treated with F or D. However, the fabrics treated with F showed a greater ability to withstand acetic acid odors than did the fabric treated with pomegranate extract, gallnut extract, or D. The anti- bacterial properties of fabric treated with pomegranate extract, gallnut extract, and F was found to be excellent (bacteriostatic reduction rate=99.9%). These results suggest that pomegranate and gallnut extracts have strong potential to be used as multi-functional agents, with both showing excellent deodorizing and antibacterial properties.

Microstructure Analysis of Ni-P-rGO Electroless Composite Plating Layer for PEM Fuel Cell Separator

Department of Nano Science & Engineering, Inje University, Gimhae 621-749, Korea(Received September 14, 2015 ; revised October 28, 2015 ; accepted October 30, 2015)AbstractRecently, fuel cell is a good alternative for energy source. Separator is a important component for fuelcell. In this study, The surface of separator was modified for corrosion resistance and electric conductivity.Reduced graphene oxide (rGO) was made by Staudenmaier’s method. Nickel, phosphorus and rGO werecoated on 6061 aluminum alloy as a separator of proton exchange membrane fuel cell by composite electrolessplating. Scanning electron microscope, energy-dispersive X-ray spectroscopy and X-ray photoelectron spec-troscopy were used to examine the morphology of Ni-P-rGO. Surface images were shown that the rGO wasdispersed on the surface of Ni-P electroless plating, and nickel was combined with the un-reduced oxygenfunctional group of rGO.

Electrochemical Characterization of Multilayered CdTe/ PSS Films Prepared by Electrostatic Self-assembly Method

Multilayered CdTe/PSS films were prepared by the electrostatic self-assembly method in an aqueous medium. Positively-charged cadmium telluride (CdTe) nanoparticles and anionic polyelectrolyte, poly (sodium 4-styrene sulfonate) (PSS) were assembled alternately in order to build up a multilayered film structure. A linear proportion of absorbance to the number of bilayers suggests that an equal amount of CdTe was adsorbed after each dipping cycle, which resulted in the buildup of a homogenous film. The binding energies of elements (Cd and Te) in multilayered CdTe/PSS film shifted from those of the CdTe nanoparticles in the pure state. This result indicates that the interfacial electron densities were redistributed by the strong electrostatic interaction between the oppositely-charged CdTe and PSS. Electrochemical properties of the multilayered CdTe/PSS films were studied in detail by cyclic voltammetry (CV).