• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.569-573
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• 1998

A water soluble polymer, polycondensate of 1-butylamine and epichlorohydrin (PBE), was synthesized by condensation of 1-butylamine and epichlorohydrin. The characteristics of PBE were determined by IR spectroscopy, low angle light scattering measurement, and $\zeta$ potential measurement. Its interactions with colloidal bentonite particles in aqueous medium were also studied. The results of the studies are as follows : PBE is a cationic polyelectrolyte carrying tertiary ammonium ions on its backbone. The average molecular weight of PBE is found to be about 1,600. The adsorption of PBE on the colloidal bentonite particles are well described with Langmuir adsorption isotherm. As the amounts of PBE adsorbed on the bentonite particles increase, the $\zeta$ potential of the particles changes its sign from negative to positive. This inversion of charge confirms that PBE is cationic in nature. The adsorption of PBE onto the bentonite particles was found to occur through cation exchange reaction. It has been shown that PBE has flocculation effects on the colloidal suspension of bentonite. It has also enhanced effects of filtrability on the digested sludge.

• Journal of Life Science
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• v.14 no.2
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• pp.368-373
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• 2004

We have obtained fertile transgenic rice plants resistant to the broad spectrum herbicide Bast $a^{(R)}$ (active ingredient phosphinothricin, PPT) by PEG-mediated transformation procedure. The plasmid pCaMV35S::Bar was used to deliver the bar gene into embryogenic suspension culture-derived protoplasts of rice (Oryza sativa L.). Transformed plants were regenerated and selected on medium containing 15 mg/l of phosphinothricin. Stable integration and expression of the bar gene in transgenic rice plants was confirmed by Southern and Northern blot analysis. Transgenic $R_1$ plants were also confirmed by assays for phosphinothricin acetyltransferase (PAT) activity. The bar gene was expressed in the primary transgenic rice plants and in the next generation progeny, in which it showed a 3 : 1 Mendelian inheritance pattern. Transgenic $R_1$ and $R_2$ plants were resistant to the herbicide Bast $a^{(R)}$ when sprayed at rates used in field practice.ice.

• KSBB Journal
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• v.16 no.4
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• pp.376-380
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• 2001

The human granulocyte-macrophage colony-stimulating factor (hGM-CSF) was produced from cell suspension culture of transgenic tobacco which was transformed by using Agrobacterium harboring the hGM-CSF gene. To improve the production of hGM-CSF in batch culture system, the effects of initial sucrose concentration and inoculum size were investigated. The results show that the hGM-CSF production was not affected by small inoculum size in medium containing either low or high concentration of sucrose. However, the production of hGM-CSF was increased under increasing of the inoculum sizes and sucrose concentration. Under the combination of inoculum and sucrose concentration, the maximum hGM-CSF production of 720 $\mu$g/L was obtained at 90 g/L of initial sucrose concentration and 110 g/L of inoculum size.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.6
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• pp.402-409
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• 2001

Different bioligands carrying synthetic adsorbents have been reported in the literature for protein separation, We have developed a novel and new approach to obtain high protein ad-sorption capacity utilizing 2-methacrylamidohistidine(MAH) as a bioligand. MAH was synthe-sized by reacting methacrylocholride and histidine, Spherical beads with an average size of 150-200㎛ were obtained by the radical suspension polymerization of MAH and 2-hydrosyethyl-methacrylate(HEMA) conducted in an aqueous dispersion medium. p(HEMA-co-MAH) beads had a specific surface area of 17.6㎡/g . Synthesized MAH monomer was characterized by NMR. p(HEMA-co-MAH) beads were characterized by swelling test, FTIR and elemental analysis. Then Cu(II) ions were incorporated onto the beads and Cu(II) loading was found to be 0.96 mmol/g.These affinity beads with a swelling ration of 65% and containing, 1.6 mmol MAH/g were used in the adsorption/desorption of human serum albumin(HSA) from both aqueous solutions and hu-man serum. The adsorption of HSA onto p(HEM-co-MAH) was low(8.8 mg/g). Cu(II) chelation onto the beads significantly increased the HSA adsorption (56.3 mg/g). The maximum HSA ad-sorption ws observed at pH 8.0 Higher HSA adsorption was observed from human plasma(94.6 mgHSA/g) Adsorption of other serum proteins were obtained as 3.7 mg/g for fibrinogen and 8.5mg/g for γ-globulin. The total protein adsorption was determined as 107.1mg/g. Desorption of HSA was obtained using 0.1 M Tris/HCl buffer containing 0.5 M NaSCN, High desorption rations(up to 98% of the adsorbed HSA) were observed. It was possible to reuse Cu(II) chelated-p(HEMA-co-MAH) beads without significant decreases in the adsorption capacities.

• Journal of Pharmaceutical Investigation
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• v.32 no.1
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• pp.27-33
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• 2002

A self-microemulsifying drug delivery system(SMEDDS) composed of Cremophor $EL^{\circledR},\;Labrasol^{circledR}$, and Lauroglycol $FCC^{circledR}$ was prepared for the enhancement of solubility, dissolution rate and bioavailability of ibuprofen(IBP), which is water-insoluble but soluble in oils and surfactants. Phase diagram with various regions including microemulsion area was depicted. The SMEDDS was encapsulated in soft gelatin capsules and their dissolution characteristics in various media were observed in comparison to the generic products commercially available in the market. Soft capsules of SMEDDS formulation showed better dissolution profiles, especially in acidic condition, than the others. For the period of 1 hr dissolution in pH 1.2 medium, it reached over 70% dissolution from soft capsules, compared to less than 40% dissolution from commercial reference tablets. On the other hand, in vivo pharmacokinetic parameters were obtained after oral administrations of different IBP preparations to Sprague Dawley rats. SMEDDS formulation showed higher $C_{max}$ and greater $AUC_{0-5hr}$ than the suspension of reference tablet or IBP powder. Therefore, it is possible to conclude that a newly developed soft capsules employing SMEDDS provides an alternative preparation to improve oral bioavailability of IBP.

• Journal of Microbiology and Biotechnology
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• v.22 no.12
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• pp.1673-1680
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• 2012

In this study, DEAE-corncobs [delignified corncob grits derivatized with 2-(diethylamino)ethyl chloride hydrochloride ($DEAE{\cdot}HCl$)] were prepared as a carrier to immobilize yeast (Saccharomyces cerevisiae) for ethanol production. The immobilized yeast cell reactor produced ethanol under optimized $DEAE{\cdot}HCl$ derivatization and adsorption conditions between yeast cells and the DEAE-corncobs. When delignified corncob grit (3.0 g) was derivatized with 0.5M $DEAE{\cdot}HCl$, the yeast cell suspension ($OD_{600}$ = 3.0) was adsorbed at >90% of the initial cell $OD_{600}$. This amount of adsorbed yeast cells was estimated to be 5.36 mg-dry cells/g-DEAE corncobs. The $Q_{max}$ (the maximum cell adsorption by the carrier) of the DEAE-corncobs was estimated to be 25.1 (mg/g), based on a Languir model biosorption isotherm experiment. When we conducted a batch culture with medium recycling using the immobilized yeast cells, the yeast cells on DEAE-corncobs produced ethanol gradually, according to glucose consumption, without cells detaching from the DEAE-corncobs. We observed under electron microscopy that the yeast cells grew on the surface and in the holes of the DEAE-corncobs. In a future study, DEAE-corncobs and the immobilized yeast cell reactor system will contribute to bioethanol production from biomass hydrolysates.

• Journal of Korean Academy of Oral Health
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• v.42 no.4
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• pp.224-228
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• 2018

Objectives: As a first step to study the anticaries effect of ethanol alone, we investigated the effects of ethanol on the expression levels of the atpB gene and proton permeability of Streptococcus mutans in suspension cultures. Methods: S. mutans UA159 was grown in brain heart infusion medium at either pH 4.8 or 6.8. The total extracted RNA was reverse-transcribed into cDNA using a $Superscript^{TM}$ First-Strand Synthesis System. The resulting cDNA and negative controls were amplified by ABI PRISM 7700 real-time PCR system with SYBR Green PCR Master Mix. For proton flux assay, bacterial suspensions were titrated to pH 4.6 with 0.5 M HCl, and then additional 0.5 M HCl was added to decrease the pH values by approximately 0.4 units. The subsequent increase in pH was monitored using a glass electrode. Ten percent (v/v) butanol was added to the suspensions at 80 min to disrupt the cell membrane. Results: In a concentration-dependent manner, ethanol alone not only decreased the growth rate of S. mutans and the expression of the atpB gene but also increased the proton permeability at both pH 4.8 and 6.8. Conclusions: These findings suggest that ethanol has the potential for an anticaries ingredient. We believe that ethanol may be used together with fluoride and/or other cariostatic agents in order to develop better anticaries toothpastes and/or mouthrinses.

• The Plant Pathology Journal
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• v.37 no.3
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• pp.215-231
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• 2021

Brown leaf spot disease caused by Nigrospora guilinensis on Phellodendron chinense occurs in a large area in Dayi County, Chengdu City, Sichuan Province, China each year. This outbreak has severely reduced the production of Chinese medicinal plants P. chinense and caused substantial economic losses. The bacterial isolate JKB05 was isolated from the healthy leaves of P. chinense, exhibited antagonistic effects against N. guilinensis and was identified as Bacillus megaterium. The following fermentation medium and conditions improved the inhibitory effect of B. megaterium JKB05 on N. guilinensis: 2% glucose, 0.1% soybean powder, 0.1% KCl, and 0.05% MgSO₄; initial concentration 6 × 10⁶ cfu/ml, and a 42-h optimal fermentation time. A composite of 0.1% nano-SiO₂ JKB05 improved the thermal stability, acid-base stability and ultraviolet resistance by 16%, 12%, and 38.9%, respectively, and nano-SiO₂ was added to the fermentation process. The best formula for the wettable powder was 35% kaolin, 4% polyethylene glycol, 8% Tween, and 2% humic acid. The following quality test results for the wettable powder were obtained: wetting time 87.0 s, suspension rate 80.33%, frequency of microbial contamination 0.08%, pH 7.2, fineness 95.8%, drying loss 1.47%, and storage stability ≥83.5%. A pot experiment revealed that the ability of JKB05 to prevent fungal infections on P. chinense increased considerably and achieved levels of control as high as 94%. The use of nanomaterials significantly improved the ability of biocontrol bacteria to control this disease.

• Advances in nano research
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• v.16 no.4
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• pp.341-352
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• 2024

This study investigates the heat and mass transfer characteristics of a MoS₂ nanoparticle suspension in ethylene glycol over a porous stretching sheet. MoS₂ nanoparticles are known for their exceptional thermal and chemical stability which makes it convenient for enhancing the energy and mass transport properties of base fluids. Ethylene glycol, a common coolant in various industrial applications is utilized as the suspending medium due to its superior heat transfer properties. The effects of variable thermal conductivity, variable mass diffusivity, thermal radiation and thermophoresis which are crucial parameters in affecting the transport phenomena of nanofluids are taken into consideration. The governing partial differential equations representing the conservation of momentum, energy, and concentration are reduced to a set of nonlinear ordinary differential equations using appropriate similarity transformations. R software and MATLAB-bvp5c are used to compute the solutions. The impact of key parameters, including the nanoparticle volume fraction, magnetic field, Prandtl number, and thermophoresis parameter on the flow, heat and mass transfer rates is systematically examined. The study reveals that the presence of MoS₂ nanoparticles curbs the friction between the fluid and the solid boundary. Moreover, the variable thermal conductivity controls the rate of heat transfer and variable mass diffusivity regulates the rate of mass transfer. The numerical and statistical results computed are mutually justified via tables. The results obtained from this investigation provide valuable insights into the design and optimization of systems involving nanofluid-based heat and mass transfer processes, such as solar collectors, chemical reactors, and heat exchangers. Furthermore, the findings contribute to a deeper understanding of stretching sheet systems, such as in manufacturing processes involving continuous casting or polymer film production. The incorporation of MoS₂-C₂H₆O₂ nanofluids can potentially optimize temperature distribution and fluid dynamics.

• The Korean Journal of Mycology
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• v.52 no.1
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• pp.55-60
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• 2024

In August 2023, leaf spot disease was observed in peanuts in Cheongju-si, Korea. Leaf spots occurred at the leaf margins and the lesions gradually expanded. Diseased leaf areas were light or dark brown and irregular in shape. A fungal isolate was obtained from symptomatic leaf and cultured on potato dextrose agar (PDA) medium at 25℃. An isolate was identified as Colletotrichum sojae based on morphological characteristics and sequences of the internal transcribed spacers, glyceraldehyde-3-phosphate dehydrogenase, chitin synthase-1, actin, and 𝛽-tubulin genes. Pathogenicity tests were performed on peanut seedlings in a conidial suspension (1×10⁶ conidia/mL). Lesions were observed on the peanut leaf 5 d after inoculation. The pathogen was re-isolated from the lesions of the inoculated leaves. To the best of our knowledge, this is the first report of anthracnose on peanut caused by C. sojae in Korea.