• Macromolecular Research
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• v.12 no.6
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• pp.608-614
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• 2004

Isotactic polypropylene (PP) surfaces were modified with argon and oxygen plasmas using a radio­frequency (RF) glow discharge at 240 mTorr and 40 W. The changes in topography and surface structure were investigated by atomic force microscopy (AFM) in conjunction with specular reflectance of infrared (IR) microspectroscopy. Under our operating conditions, the AFM image analysis revealed that longer plasma treatment resulted in significant ablation on the PP surface, regardless of the kind of plasma employed, but the topography was dependent on the nature of the gases. Specular reflectance IR spectroscopic analysis indicated that the constant removal of surface material was an important ablative aspect when using either plasma, but the nature of the ablative behavior and the resultant aging effects were clearly dependent on the choice of plasma. The use of argon plasma resulted in a negligible aging effect; in contrast, the use of oxygen plasma caused a noticeable aging effect, which was due to reactions of trapped or isolated radicals with oxygen in air, and was partly responsible for the increased surface area caused by ablation. The use of oxygen plasma is believed to be an advantageous approach to modifying polymeric materials with functionalized surfaces, e.g., for surface grafting of unsaturated monomers and incorporating oxygen-containing groups onto PP.

• Journal of Environmental Health Sciences
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• v.32 no.1 s.88
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• pp.60-66
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• 2006

Bisphenol A(BPA) was known as an endocrine disrupting chemical. This study was conducted to assess the effect of BPA, weaker estrogen, on the preneoplastic and neoplastic lesions induced by diethylnitrosamine (DEN). One hundred male F344 rats were divided into four groups which were treated with DEN followed by BPA. To make liver tumor early, we conducted that DEN containing osmotic pump implanted into rat abdominal cavity. Then diet containing BPA were fed to the rats. All animals were sacrificed at 10 and 18 weeks. Body weights were significantly decreased in 4000ppm at 18 weeks. Relative Liver weights of 4000 ppm BPA treated group were significantly increased compared to that of DEN alone group at 18 weeks. There were no significant differences of liver tumor incidences. Sum area of GST-P positive foci and BrdU labeling indices of BPA treated group were not significantly different compared to those of control group. These results suggest that BPA have no effects in preneoplastic and neoplastic lesions on DEN-induced hepatocarcinogenesis.

• The Microorganisms and Industry
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• v.19 no.2
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• pp.34-41
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• 1993

Industrial strain improvement is concerned with developing or modifying microorganisms used in production of commercially important fermentation products. The aim is to reduce the production cost by improving productivity of a strain and manipulating specific characteristics such as the ability to utilize cheaper raw materials or resist bacteriophages. The traditional empirical approach to strain improvement is mutation combined with selection and breeding techniques. It is still used by us to improve the productivity of organisms in amino acids, organic acids and enzymes production. The breeding of high L-lysine-producing strain Au112 is one of the outstanding examples of this approach. It is a homoserine auxotroph with AEC, TA double metabolic analogue resistant markers. The yield reaches 100 g/l. Besides, the citric acid-producing organism Aspergillus niger, Co827, its productivity reaches the advanced level in the world, is also the result of a series mutations especially with $^60Co{\gamma}$-radiation. The thermostable .alpha.-amylase producing strain A 4041 is the third example. By combining physical and chemical mutations, the strain A 4041 becomes an asporogenous, catabolite derepressed mutant with rifamycin resistant and methionine, arginine auxotroph markers. The .alpha.-amylase activity reaches 200 units/ml. The fourth successful example of mutation in strain improvement is the glucoamylase-producing strain Aspergillus niger SP56, its enzyme activity is 20,000 units/ml, 4 times of that of the parental strain UV-11. Recently, recombinant DNA approach provides a worthwhile alternative strategy to industrial strain improvement. This technique had been used by us to increase the thermostable .alpha.-amylase production and on some genetic researches.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.129-129
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• 2013

Nanometal alloy catalysts have been found to significantly increase catalytic efficiency, compared to the monometallic counterparts. This enhancement can be attributed to various alloying effects: i) the existence of uniquemixed-metal surface sites [the so called ensemble (geometric) effect]; ii) electronic state changes due to metal-metal interactions [the so called ligand (electronic) effect]; and iii) strain caused by lattice mismatch between the alloy components [the socalled strain effect]. In addition, the presence of low-coordination surface atoms and preferential exposure of specific facets [(111), (100), (110)] in association with the size and shape of nanoparticle catalysts [the so called shape-size-facet effect] can be another important factor for modifying the catalytic activity. However, mechanisms underlying the alloying effect still remain unclear owing to the difficulty of direct characterization. Computational approaches, particularly the prediction using first-principles density functional theory (DFT), can be a powerful and flexible alternative for unraveling the role of alloying effects in catalysis since those can give us quantitative insights into the catalytic systems. In this talk, I will present the underlying principles (such as atomic arrangement, facet, local strain, ligand interaction, and effective atomic coordination number at the surface) that govern catalytic reactions occurring on Pd-based alloys using the first-principles calculations. This work highlights the importance of knowing how to properly tailor the surface reactivity of alloy catalysts for achieving high catalytic performance.

• BMB Reports
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• v.34 no.5
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• pp.408-414
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• 2001

Ornithine decarboxylase (EC 4.1.1.17) is an essential enzyme for polyamine synthesis and growth in mammalian cells and plants. We compared the biochemical and immunological properties of rat and Nicotiana glutinosa ODC by cloning and expressing the recombinant proteins. The primary amino acid sequence between rat and N. glutinosa ODC had a 40% homology The molecular weight of the overexpressed rat ODC was 53 kDa, and that of N. glutinosa was 46.5 kDa. Adding 1 mM of putrescine to the enzyme reaction mixture inhibited both rat and N. glutinosa ODC activity to 30%. Agmatine had an inhibitory effect only on N. glutinosa ODC. Cysteine and lysine modifying reagents reduced both ODC activities, verifying the key roles of cysteine and lysine residues in the catalytic mechanism of ODC. ELISA was performed to characterize the immunological difference between the rat and plant ODC. Both the rat and N. glutinosa ODC were recognized by the polyclonal antibody that was raised against purified N. glutinosa ODC, but the rat ODC was 50-fold less sensitive to the antibody binding. These results indicate that even though both ODCs have the same evolutionary origin, there seems to be a structural distinction between the species.

• Environmental Engineering Research
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• v.22 no.2
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• pp.149-156
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• 2017

Chromium(III) recovery from tanning wastewater by means of adsorption on activated carbon and elution with sulfuric acid was studied. Tests were carried out at laboratory scale on an effluent of industrial origin. Initially, proteinaceous materials and fats were separated via sieving followed by ultrafiltration. The chemical composition of the sample thus precleansed was (in g/L): 1.09 chromium(III); 10.36 sulfate; 11.10 sodium; 9.57 chloride; 0.40 proteinaceous materials; and 0.20 fats. Adsorptions were made at 20, 30, and $40^{\circ}C$, establishing what temperature favored chromium(III) uptake. At $40^{\circ}C$, the maximum cation fixation was 40.2 mg/g, and the lowest content in an equilibrium solution was 3.9 mg/L. As regards sodium, chloride, and sulfate, the concentrations before and after the treatment were similar. Likewise, it was found that protons were also retained, modifying the pH of the liquid medium. Adsorption isotherms were analyzed using the Langmuir, Temkin, and Freundlich models. Finally, the extraction of the adsorbed tanning agent with sulfuric acid was evaluated. A recovery of 96.5% was achieved with 0.9 N at $70^{\circ}C$ (13.23 g/L $Cr^{3+}$; 42.98 g/L sulfate; and 0.40 g/L NaCl).

• The Microorganisms and Industry
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• v.15 no.1
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• pp.38-42
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• 1989

Industrial strain Improvement is concerned with developing or modifying microorga-nisms used In production of commercially important fermentation products. The aim is to reduce the production cost by improving productivity of a strain and manipulating specific cilarafteristic such as the ability to utilize cheaper raw materials or resist bacteriophages. The traditional empiri-cal approach to strain improvement is mutation combined with selection and breeding techniques. It is still used by us to improve the productivity of organisms in amino acids. organic acids andenzymes production. The breeding of high L-lysine-producing strain Au112 is one of the outstanding examples of this approach. It is it homoserine auxotroph with AEC, TA double metabolicanalogue resistant markers. The yield reaches 100g/1. Resides, the citric acid-producing organism Aspergillus nuger, Co827, its productivity reches the advanced level in the world, is also the result of a series mutations expecially with Co Y-radiation. The thermostable a-amylaseroducing strain A 4041 is the third example. By combining physical and chemical multations. the strain ,A 4041becomes an asporogenous, catabolite derepressed mutant with rifamycin resistant and methionine, arginine auxotroph markers. The a-amylase activity reaches 200 units/ml. The fourth successful example of mutation in strain improvement is the glucoamylase-producing strain Aspergillus nigerSP56 its enzyme activity is 20,000 units/ml, 4 times of that of the parental strain UV_11. Recently recombinant DNA approach Provides a worth while alternative strategy to Industrial strain improve-ment. This technique had been used by us to increase the thermostable a-amylase production and on some genetic researches.

• Journal of Ginseng Research
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• v.36 no.1
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• pp.16-26
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• 2012

Ginseng is one of the most widely used herbal medicines and is reported to have a wide range of therapeutic and pharmacological applications. Ginseng may also be potentially valuable in treating cardiovascular diseases. Research concerning cardiovascular disease is focusing on purified individual ginsenoside constituents of ginseng to reveal specific mechanisms instead of using whole ginseng extracts. The most commonly studied ginsenosides are $Rb_1$, $Rg_1$, $Rg_3$, $Rh_1$, Re, and Rd. The molecular mechanisms and medical applications of ginsenosides in the treatment of cardiovascular disease have attracted much attention and been the subject of numerous publications. Here, we review the current literature on the myriad pharmacological functions and the potential benefits of ginseng in this area. In vitro investigations using cell cultures and in vivo animal models have indicated ginseng's potential cardiovascular benefits through diverse mechanisms that include antioxidation, modifying vasomotor function, reducing platelet adhesion, influencing ion channels, altering autonomic neurotransmitters release, and improving lipid profiles. Some 40 ginsenosides have been identified. Each may have different effects in pharmacology and mechanisms due to their different chemical structures. This review also summarizes results of relevant clinical trials regarding the cardiovascular effects of ginseng, particularly in the management of hypertension and improving cardiovascular function.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.425-432
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• 1996

Integrated performance test of Chemical and Volume Control System (CVCS) was successfully performed in 1994. However, an extensive effort to correct hardware and software problems in the letdown line was required mainly due to the lack of adequate simulation code to predict the test accurately. Although the LTC computer code was used during the YGN 3'||'&'||'4 NSSS design process, the code can not satisfactorily predict the test due to its insufficient letdown line modeling. This study developed a numerical model to simulate the letdown test by modifying the current LTC code, and then verified the model by comparing with the test data. The comparison shows that the modified LTC computer code can predict the transient behavior of letdown system tests very well. Especially, the model was verified to be able to predict the "Stiction" phenomena which caused instantaneous fluctuations in the letdown backpressure and flowrate. Therefore, it is concluded that the modified LTC computer code with the ability of calculating the "Stiction" phenomena wi11 be very useful for future plant desist and test predictions.predictions.

• ALGAE
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• v.36 no.3
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• pp.195-206
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• 2021

Increasing inputs of dissolved organic matter (DOM) to northern lakes is resulting in 'lake browning.' Lake browning profoundly affects phytoplankton community composition by modifying two important environmental drivers-light and nutrients. The impact of increased DOM on native isolates of red and green-pigmented cyanobacteria identified as Pseudanabaena, which emerged from a Dolichospermum bloom (Dickson Lake, Algonquin Provincial Park, Ontario, Canada) in 2015, were examined under controlled laboratory conditions. The genomes were sequenced to identify phylogenetic relatedness and physiological similarities, and the physical and chemical effects of increased DOM on cellular performance and competitiveness were assessed. Our study findings were that the isolated red and green phenotypes are two distinct species belonging to the genus Pseudanabaena; that both isolates remained physiologically unaffected when grown independently under defined DOM regimes; and that neither red nor green phenotype achieved a competitive advantage when grown together under defined DOM regimes. While photosynthetic pigment diversity among phytoplankton offers niche-differentiation opportunities, the results of this study illustrate the coexistence of two distinct photosynthetic pigment phenotypes under increasing DOM conditions.