Showing papers by "Chonbuk National University published in 2002"
TL;DR: The OFS ethanol extract was found to be effective in protecting plasmid DNA against the strand breakage induced by hydroxyl radicals in a Fenton's reaction mixture and showed significant dose-dependent protection of mouse splenocytes against glucose oxidase-mediated cytotoxicity.
Abstract: An ethanol extract of the stem of Opuntia ficus-indica var. saboten (OFS) was assessed to determine the mechanism(s) of its antioxidant activity. The ethanol extract exhibited a concentration-dependent inhibition of linoleic acid oxidation in a thiocyanate assay system. In addition, the OFS extract showed dose-dependent free-radical scavenging activity, including DPPH radicals, superoxide anions (O(2)(*-)), and hydroxyl radicals (*OH), using different assay systems. The OFS ethanol extract was also found to be effective in protecting plasmid DNA against the strand breakage induced by hydroxyl radicals in a Fenton's reaction mixture. Furthermore, the extract showed significant (p < 0.01) dose-dependent protection of mouse splenocytes against glucose oxidase-mediated cytotoxicity. Finally, the OFS extract was characterized as containing a high amount of phenolics (180.3 mg/g), which might be the active compounds responsible for the antioxidant properties of the OFS extract.
537 citations
TL;DR: In this paper, single-crystalline zinc oxide (ZnO) nanowires with high density were successfully synthesized on nickel monoxide (NiO) catalyzed alumina substrate through a simple metal-vapor deposition method at an extremely low temperature (450 °C).
431 citations
TL;DR: In this article, a chemical crosslinking method was used to crosslink the nanoscale polyvinyl alcohol (PVA) fiber aggregates, and the results showed that the properly crosslinked PVA fiber aggregate had better antiwater solubility and mechanical properties than the non-crosslinked aggregate.
Abstract: Nanoscale poly(vinyl alcohol) (PVA) fiber (100–500 nm) aggregates were prepared with an electrospinning technique. Additionally, a chemical crosslinking method was used to crosslink the nanoscale PVA fiber aggregates. Differential scanning calorimetry, wide-angle X-ray diffraction, and scanning electron microscopy techniques were employed to characterize the PVA fiber aggregates. The different crosslinking densities of the PVA fiber aggregates were obtained through the control of the weight percentage of glyoxal to PVA. The crosslinking densities due to heat treatment and chemical crosslinking were studied. The influence of heat treatment could be neglected in contrast to chemical crosslinking when the curing temperature was 120 °C. The primary factor that affected the crosslinking density was the volume of the chemical crosslinking agent. The results showed that the properly crosslinked PVA fiber aggregates had better antiwater solubility and mechanical properties than the noncrosslinked PVA fiber aggregates. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1261–1268, 2002
342 citations
TL;DR: It is found that parthenolide effectively inhibits hepatoma cell growth in a tumor cell-specific manner and triggers apoptosis of hepatoma cells and may be useful chemotherapeutic agents to treat these invasive cancers.
314 citations
TL;DR: The toxicity of pipernonaline is comparable to that of pirimiphos-methyl as a mosquito larvicide and no activity was observed with piperettine, piperine, or piperlongumine in tests with available components derived from P. longum.
Abstract: Mosquito larvicidal activity of Piper longum fruit-derived materials against the fourth-instar larvae of Aedes aegypti was examined. A crude methanol extract of P. longum fruits was found to be active against the larvae, and the hexane fraction of the methanol extract showed a strong larvicidal activity of 100% mortality. The biologically active component of P. longum fruits was characterized as pipernonaline by spectroscopic analyses. The LC(50) value of pipernonaline was 0.25 mg/L. The toxicity of pipernonaline is comparable to that of pirimiphos-methyl as a mosquito larvicide. In tests with available components derived from P. longum, no activity was observed with piperettine, piperine, or piperlongumine.
285 citations
TL;DR: In this in vitro study, four classes of endodontic sealers were compared for their ability to bond to dentin or gutta-percha and it was indicated that AH 26 gave the significantly highest bonds to gutta -percha.
284 citations
TL;DR: The results indicated that the veA gene is a positive regulator in sexual development and simultaneously a negative one in asexual development.
267 citations
TL;DR: In this article, the authors evaluated the effects of solvent composition with respect to the solution concentration, applied electric field, and tip-to-collector distance on the morphology of electrospun polyvinyl chloride (PVC) fibers.
Abstract: We evaluated the effects of the solvent composition with respect to the solution concentration, applied electric field, and tip-to-collector distance on the morphology of electrospun poly(vinyl chloride) (PVC) fibers. The solvent volume ratio was strongly correlated with the diameter of the electrospun fibers with respect to the other processing parameters. Electrospun PVC fibers dissolved in tetrahydrofuran (THF) had diameters ranging from 500 nm to 6 μm; those dissolved in N,N-dimethylformamide (DMF) had an average diameter of 200 nm. The diameters of the electrospun fibers were obtained from narrow to broad distributions with the solvent composition. Also, the diameters of fibers electrospun from a mixed solvent of THF and DMF were less than 1 μm. The mechanical properties of electrospun PVC nonwoven mats depended on the fiber orientation and linear velocity of the drum surface. With increasing linear velocity of the drum surface, electrospun PVC fibers were arranged toward the machine direction, and the dimensions of the spiral path were shorter. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2259–2268, 2002
251 citations
TL;DR: Simulated annealing (SA), a meta-heuristic, is employed in this study to determine a scheduling policy so as to minimize total tardiness, and shows that the proposed SA method significantly outperforms a neighborhood search method in terms of total tardyness.
Abstract: This paper presents a scheduling problem for unrelated parallel machines with sequence-dependent setup times, using simulated annealing (SA). The problem accounts for allotting work parts of L jobs into M parallel unrelated machines, where a job refers to a lot composed of N items. Some jobs may have different items while every item within each job has an identical processing time with a common due date. Each machine has its own processing times according to the characteristics of the machine as well as job types. Setup times are machine independent but job sequence dependent. SA, a meta-heuristic, is employed in this study to determine a scheduling policy so as to minimize total tardiness. The suggested SA method utilizes six job or item rearranging techniques to generate neighborhood solutions. The experimental analysis shows that the proposed SA method significantly outperforms a neighborhood search method in terms of total tardiness.
233 citations
Journal Article•
TL;DR: The amino acid sequences that are deduced from the genes for the determined-neutralizing epitope were highly homologous among the PEDV strains that were isolated from different geographical areas, which suggests conservation of the antigen gene.
Abstract: In order to identify the neutralizing epitope of the porcine epidemic diarrhea virus (PEDV), the spike protein region that is presumed to contain the virus-neutralizing epitope was determined This was based on the sequence information for the neutralizing epitope of the transmissible gastroenteritis virus (TGEV) A recombinant protein that corresponds to the spike region of TGEV was produced, and polyclonal antisera were generated using the recombinant protein It was discovered that polyclonal antisera significantly inhibited plaque formation by PEDV, suggesting that this region of the spike protein contains the epitope(s) that is capable of inducing PEDV-neutralizing antibodies In addition, the region that corresponds to the neutralizing epitope of TGEV may also be involved in neutralizing PEDV, although the two viruses are serologically quite distinct Finally, the amino acid sequences that are deduced from the genes for the determined-neutralizing epitope were highly homologous among the PEDV strains that were isolated from different geographical areas, which suggests conservation of the antigen gene
218 citations
TL;DR: In this article, the crystalline phase and morphology of alumina-borate fibres were largely influenced by the calcination temperature, and they were characterized by SEM, XRD and FT-IR.
Abstract: Alumina-borate/PVA composite fibres were prepared using sol–gel processing and an electrospinning technique. After calcination of the thin fibres, ultra-fine fibres of alumina-borate oxide with a diameter of about 550 nm could be prepared. The fibres were characterized by SEM, XRD and FT-IR. The results showed that the crystalline phase and morphology of alumina-borate fibres were largely influenced by the calcination temperature.
01 Aug 2002
TL;DR: It was found that chemical treatment with phosphoric acid solution significantly affected the degree of adhesion at interfaces between fibers and resin matrix, resulting in improved mechanical interfacial strength in the composites.
Abstract: In this work, the effects of chemical treatment on Kevlar 29 fibers have been studied in a composite system. The surface characteristics of Kevlar 29 fibers were characterized by pH, acid–base value, X-ray photoelectron spectroscopy (XPS), and FT-IR. The mechanical interfacial properties of the final composites were studied by interlaminar shear strength (ILSS), critical stress intensity factor ( K IC ), and specific fracture energy ( G IC ). Also, impact properties of the composites were investigated in the context of differentiating between initiation and propagation energies and ductile index (DI) along with maximum force and total energy. As a result, it was found that chemical treatment with phosphoric acid solution significantly affected the degree of adhesion at interfaces between fibers and resin matrix, resulting in improved mechanical interfacial strength in the composites. This was probably due to the presence of chemical polar groups on Kevlar surfaces, leading to an increment of interfacial binding force between fibers and matrix in a composite system.
TL;DR: In this paper, Nanoscaled PVA nano-fibers were obtained by changing solution concentration, voltage and tip-to-collector distance (TCD), which affected the fiber diameter evidently.
Abstract: Nanoscaled PVA fibers were prepared by electrospinning. This paper described the electrospinning process, the processing conditions, fiber morphology, and some potential applications of the PVA nano-fibers. PVA fibers with various diameters (50–250 nm) were obtained by changing solution concentration, voltage and tip to collector distance (TCD). The major factor was the concentration of PVA solution which affected the fiber diameter evidently. Increasing the concentration, the fiber diameter was increased, and the amount of beads was reduced even to 0%. The fibers were found be efficiently crosslinked by glyoxal during the curing process. Phosphoric acid was used as a catalyst activator to reduce strength losses during crosslinking. Scanning electron micrograph (SEM) and differential scanning calorimetric (DSC) techniques were employed to characterize the morphology and crosslinking of PVA fibers. It was found that the primary factor which affected the crosslinking density was the content of chemical crosslinking agent.
TL;DR: The results suggest that the flavonoid derivatives in F(2) are the compounds in the RVS ethanol extract that act as antioxidants.
TL;DR: It is concluded that linolenic acid has a strong antimicrobial activity against B. cereus and S. aureus, and that linorenic acid combined with monoglyceride showed stronger antimacterial activity than using linolenoic acid alone.
Abstract: The antimicrobial effect of linolenic acid with or without monoglyceride (glycerol laurate or glycerol myristate) against six food-borne microorganisms was determined in broth medium. Minimum inhibitory concentration of linolenic acid on Bacillus cereus and Staphylococcus aureus was 20 and 50 ppm, respectively. The growth of B. cereus treated with linolenic acid at 10 ppm with 10 ppm monoglyceride was more inhibitory than that of linolenic acid alone, and the viable cell population was reduced 2-4 log cycles compared to that of the control. When linolenic acid was added at that level, the adenosine triphosphate (ATP) concentration of extracellular fluid was drastically increased compared with that of the control, and the combined effect with monoglyceride was higher than that with linolenic acid alone. However, the intracellular ATP concentration decreased compared with that of the control. From these results, we concluded that linolenic acid has a strong antimicrobial activity against B. cereus and S. aureus, and that linolenic acid combined with monoglyceride showed stronger antimicrobial activity than using linolenic acid alone.
TL;DR: Results indicate that DADS-induced apoptosis is triggered by the generation of hydrogen peroxide, activation of caspase-3, degradation of PARP, and fragmentation of DNA.
TL;DR: Results suggest that aucubin is a specific inhibitor of NF-κB activation in mast cells, which might explain its beneficial effect in the treatment of chronic allergic inflammatory diseases.
TL;DR: A personalized recommendation procedure is introduced by which to get further recommendation effectiveness when applied to Internet shopping malls and experimental results show that choosing the right level of product taxonomy and the right customers increases the quality of recommendations.
TL;DR: Results suggest that V EGF is one of the major determinants of TDI-induced asthma and that the inhibition of VEGF may be a good therapeutic strategy.
Abstract: Isocyanate chemicals, including toluene diisocyanate (TDI), are currently the most common causes of occupational asthma. Although considerable controversy remains regarding its pathogenesis, TDI-induced asthma is characterized by hyperresponsiveness and inflammation of the airways. One of the histological hallmarks of inflammation is angiogenesis, but the possible role of vascular endothelial growth factor (VEGF), a potent angiogenic cytokine, in TDI-induced asthma is unknown. We developed a murine model to investigate TDI-induced asthma by performing two courses of sensitization with 3% TDI and one challenge with 1% TDI using ultrasonic nebulization to examine the potential involvement of VEGF in that disease. These mice develop the following typical pathophysiological features: airway hyperresponsiveness, airway inflammation, and increased VEGF levels in the airway. Administration of VEGFR inhibitors reduced all these pathophysiological symptoms. These results suggest that VEGF is one of the major determinants of TDI-induced asthma and that the inhibition of VEGF may be a good therapeutic strategy.
TL;DR: In this article, the authors tried to improve the hydrogen sorption properties of Mg by mechanical grinding under H 2 (reactive mechanical grinding) with oxides Cr 2 O 3, Al 2 O3 and CeO 2.
TL;DR: In this article, the authors synthesized high-quality gallium nitride (GaN) nanowires by a chemical-vapor-deposition method and studied the electrical transport properties.
Abstract: We have synthesized high-quality gallium nitride (GaN) nanowires by a chemical-vapor-deposition method and studied the electrical transport properties. The electrical measurements on individual GaN nanowires show a pronounced n-type field effect due to nitrogen vacancies in the whole measured temperature ranges. The n-type gate response and the temperature dependence of the current–voltage characteristics could be understood by the band bending at the interface of the metal electrode and GaN wire. The estimated electron mobility from the gate modulation characteristics is about 2.15 cm2/V s at room temperature, suggesting the diffusive nature of electron transport in the nanowires.
TL;DR: As a naturally occurring tyrosinase inhibitor, 3,4-dihydroxycinnamic acid and 4-hydroxy-3-methoxycinnamamic acid may be useful as new agents to inhibit the oxidation of L-3,4, dihydroxyphenylalanine (L-DOPA) by mushroom tyrosine.
Abstract: The inhibition of mushroom tyrosinase by Pulsatilla cernua root-derived materials was evaluated. The bioactive components of Pulsatilla cernua root were characterized by spectroscopic analyses as 3,4-dihydroxycinnamic acid and 4-hydroxy-3-methoxycinnamic acid, which exhibited potent antityrosinase activity. The ID50 values of 3,4-dihydroxycinnamic acid and 4-hydroxy-3-methoxycinnamic acid were 0.97 and 0.33 mM, respectively. The compounds isolated from Pulsatilla cernua roots exhibited noncompetitive inhibition against oxidation of L-DOPA by mushroom tyrosinase. This activity was compared with that of three cinnamic acid derivatives and four well-known tyrosinase inhibitors. The ID50 of 4-hydroxy-3-methoxycinnamic acid exhibited superior activity relative to anisaldehyde, anisic acid, benzoic acid, benzaldehyde, cinnamic acid, and cinnamaldehyde; but antityrosinase inhibitors and cinnamic acid derivatives, except for cinnamyl alcohol, were slightly more effective than 3,4-dihydroxycinnamic acid. In the ca...
TL;DR: Hybrid nanocomposites based on organophillic montmorillonite (MMT) and ethylene-propylene-diene rubber (EPDM) have been prepared by a melt compounding process as discussed by the authors.
Abstract: Hybrid nanocomposites based on organophillic montmorillonite (MMT) and ethylene–propylene–diene rubber (EPDM) have been prepared by a melt compounding process. From analysis by X-ray diffraction and transmission electron microscopy, the rubber molecules were found to be intercalated into the galleries of organoMMT and the silicate layers of organoMMT are uniformly dispersed as platelets of 50–80 nm thickness in the EPDM matrix. Dynamic mechanical studies reveal a strong rubber–filler interaction in the hybrid nanocomposite which is manifested in the lowering of tan δ at the glass transition temperature. The hybrid nanocomposites exhibit great improvement in tensile and tear strength, and modulus, as well as elongation-at-break. Moreover, the permeability of oxygen for the hybrid nanocomposite was reduced remarkably.
© 2002 Society of Chemical Industry
Posted Content•
TL;DR: In this article, the fundamental gaugino and higgsino parameters of the chargino and neutralino system in supersymmetric theories can be determined in high-precision experiments at $e^+e^-$ linear colliders.
Abstract: In the preceding reference [CKMZ] we have shown how the fundamental gaugino and higgsino parameters of the chargino and neutralino system in supersymmetric theories can be determined in high--precision experiments at $e^+e^-$ linear colliders. Within the Minimal Supersymmetric Standard Model these parameters can be reconstructed completely even if only the light charginos $\tilde{\chi}^\pm_1$ and the light neutralinos $\tilde{\chi}^0_1$ and $\tilde{\chi}^0_2$ are kinematically accessible in the initial phase of these machines, as demonstrated in this Addendum.
TL;DR: In this paper, the authors used electrospun fibres of polyvinyl alcohol/silica composite as a precursor to obtain amorphous silica nanofibres with diameters of 200-400 nm.
Abstract: For the first time, silica nanofibres with diameters of 200–400 nm were prepared by using electrospun fibres of polyvinylalcohol/silica composite as precursor. The products were characterized by the scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR), and x-ray diffractometry (XRD) methods. The results showed that the crystalline phase and morphology of silica fibres were substantially influenced by the calcination temperature. The amorphous silica nanofibres could be obtained at 550oC.
TL;DR: The MPC polymer was a useful additive for reducing the inflammatory reaction of adherent cells on PLGA.
TL;DR: The dynamic CT and MRI findings have been summarized as early enhancement of peripheral portal veins, and wedge-shaped transient parenchymal enhancement during the hepatic arterial phase.
Abstract: With the increased temporal resolution available in dynamic computed tomography (CT) and magnetic resonance imaging (MRI), hepatic arterioportal shunts are now more frequently encountered than in the past. The condition occurs in various hepatic diseases in which portal or hepatic venous flow is compromised. The underlying mechanism and the degree of shunt affect its appearance at dynamic imaging. The dynamic CT and MRI findings have been summarized as early enhancement of peripheral portal veins, and wedge-shaped transient parenchymal enhancement during the hepatic arterial phase. Recognition of arterioportal shunt can suggest the presence of a previously unsuspected disorder and avoids false-positive diagnosis or overestimation of a hepatic disease. Familiarity with the pathophysiology of arterioportal shunt also allows investigation of the hepatic hemodynamic changes occurring in various hepatic diseases.
TL;DR: The primary purpose of this paper is to prove the effectiveness of class-modular neural networks in terms of their convergence and recognition power.
TL;DR: Data indicate that Runx2 expression in osteoblasts is reduced by hypoxia, and may be a mechanism of osteoporosis by decreased vascular supply.