• Journal of the Mineralogical Society of Korea
• /
• v.11 no.2
• /
• pp.97-105
• /
• 1998

Weathering of biotite in Palgonsan granite was studied by using X-ray diffraction, optical microscopy, scanning electron microscopy, and electron probe micro analysis. Biotite altered to biotite/vermiculite regular mixed layer mineral (B/V) in the early stage of weathering. Although partially replaced by kaolinite with the progress of weathering. B/V is the major weathering product of biotite throughout the profile. During the formation of B/V, Mg, Fe and K are removed from a biotite layer to form a vermiculite layer by about 28%, 44% and 88%, respectively, whereas the Ti content is not changed. Considerable volume increase after the kaolinitization of B/V suggests that Al and Si are largely introduced from the external weathering solution. The silicate lattice templet of a weathering biotite facilitated the nucleation and growth of kaolinite. In the Palgongsan granite weathering profile, plagioclase weathered mostly into halloysite whereas biotite greatly contributes to the kaolinite crystallization though its small content in fresh rock.

• Korean Journal of Microbiology
• /
• v.22 no.3
• /
• pp.175-181
• /
• 1984

In order to develope a protoplast fusion system for industrial coryneform bacteria, the optimum conditions for the formation and regeneration of progoplast were examined for Brevibacterium flavum and Corynebacterium glutamicum and the protoplast fusion was performed. For the formation of the protoplast of B. flavum and C. glutamicum, the optimum time for penicillin G. treatment to obtain protoplast was mid-exponential growth phase ($O.D_{580}=0.6-0.8,\;8.0{\times}10^7-1.0{\times}10^8cell/ml$). At the optimum conditions (0.3units/ml penicillin G and $400{\mu}g/ml$ lysoyme for treatement), frequencies of protoplast formation and protoplast regeneration were 99% and 25%, respectively. Protoplast regeneration frequency was highest under the optimum conditions for the protoplast formation. Addition of 25mM $Mg^{2+}\;and\;50mM\;Ca^{2+}$ to the regeneration medium further increased the regeneration frequencies. The protoplast fusion frequencies of B. flavum and C. glutamicum in intraspecies fusion were $1.0{\times}10^{-8}\;and\;7.8{\times}10^{-4}$, of the regenerated protoplast respectively, when 33% of PEG (polythylene glycol) 6,000 was used as the fusing agent.

• Korean Journal of Medicinal Crop Science
• /
• v.11 no.5
• /
• pp.397-401
• /
• 2003

Digitalis purpurea L. is a medicinal herb and have been used to congestive heart failure, mycocardial infarction, edema, angina etc. A protocol has been developed for in vitro propagation of adventitious shoot buds directly from leaf segments of D. purpurea Leaf explants of D. purpurea directly formed shoot buds when cultured on a MS medium supplemented with $2\;mg/l$ BA and $0.1\;mg/l$ IAA for 5 weeks. Adventitious shoots were multiplied by subculturing on the $B_5$ medium and shoot elongation was developed by subculturing on the WPM medium. Root formation from the shoot regenerated was achieved on MS basal medium containing 1 mg/ IBA.

• Journal of the Korean Society of Safety
• /
• v.24 no.6
• /
• pp.63-71
• /
• 2009

In order to improve flame retardancy, the halogen free organic melamine phosphate(M-P) flame retardant was synthesized from melamine and phosphoric acid by the reaction of precipitation. The ignition test was carried out preparing hybrid flame retardant compound($H_bFRC$) consisting of organic M-P and inorganic Mg$(OH)_2$ as a flame retardant in the polyolefin resins. The flame retardancy and mechanical properties of flame retardant aluminum composite panel($H_bFRC$-ACP) were performed to investigate the possibility of the composite material, which was contained M-P, as a inner core for $H_bFRC$-ACP. For this study, the results of ignition test indicate that a char formation and drip suppressing effect, and combustion time reduced as the content of M-P increased. The limited oxygen index(LOI) values were measured 17.4vol% and 31.5vol% for LDPE only and $H_bFRC$-3(M-P content: 15wt%), respectively. And it was verified that the $H_bFRC$-3 was needed more oxygen quantity with the increase of M-P content when it combustion. Also, the results from thermogravimetric analysis were observed endothermic peak at $350^{\circ}C$ and $550^{\circ}C$, it was confirmed predominant thermal stability though the wide temperature range by the mixture of M-P and Mg$(OH)_2$. The LDPE-ACP (using only LDPE as a inner core), $35.13kW/m^2$ of heat release rate(HRR) and 13.43MJ/m2 of total heat release(THR) were measured while the $H_bFRC$-ACP, $10.44kW/m^2$ of HRR and 1.84MJ/m2 of THR were measured by results of cone calorimeter test. In case of $H_bFRC$-ACP, the average gas emission amount of CO and $CO_2$ could be decreased down to 25% and 20%, respectively, in comparison with LDPE-ACP. The mechanical properties such as tensile strength, bending strength and adhesion strength of $H_bFRC$-ACP were revealed slightly high values $54N/mm^2$, $152N/mm^2$ and 120N/25mm, respectively, compared with LDPE-ACP. It was confirmed that flame retardancy was improved with the synergy effect because of char formation by M-P and hydrolysis by Mg$(OH)_2$. The result of this study suggest that $H_bFRC$ can be applied for an adequate halogen free flame retardant composite material as a inner core for ACP.

• Corrosion Science and Technology
• /
• v.18 no.6
• /
• pp.243-252
• /
• 2019

The pitting corrosion and inhibition studies of AZ31B magnesium alloy were investigated in the alkaline solution (pH12) with chloride and inhibitors. The corrosion behavior of passive film with/without Cl^- in the alkaline electrolyte were conducted by polarization curve and immersion tests in the presence of various additives (inhibitors) to clarify the inhibition efficiency of pitting corrosion at higher potential region. Critical concentration of pitting corrosion for Mg alloy was evaluated with 0.005 M NaCl in 0.01 M NaOH on the anodic polarization behavior. Critical pitting of AZ31B Mg alloy in 0.01 M NaOH is a function of chlorides; E_pit = - 1.36 - 0.2 log [Cl^-]. When the Sodium Benzoate (SB) was only used as an inhibitor, a few metastable pits developed on the Mg surface by an immersion test despite no pitting corrosion on the polarization curve meaning that adsorption of SB on the surface is insufficient protection from pitting corrosion in the presence of chloride. The role of SB and Sodium Dodecylbenzenesulfonate (SDBS) inhibitors for the Mg alloy surface in the presence of chloride was suppressed from pitting corrosion to co-adsorb on the Mg alloy surface with strong formation of passive film preventing pitting corrosion.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.17 no.2
• /
• pp.560-567
• /
• 2003

Antimetastatic effects of Agaricus mixed prescription (AMP) were studied in the respect of blood-borne metastasis. For this aim, cytotoxicity against various cancer cells and normal cells, Chicken Chorioallantoic membrane (CAM) assay, cancer cell adhesion assay, platelet aggregation assay, pulmonary colonization, life span of S-180 implanted mice, and cytokine release assay were evaluated, respectively. The results were summarized as follows; AMP did not exert any cytotoxicity against all cell lines with IC50 of 25mg/ml on B16BL6. AMP disrupted formation of CAM at 1mg/ml. AMP was suppressive in adhesion assay of B16BL6. AMP also inhibited tumor induced platelet aggregation. In pulmonary colonization assay by B16BL6, the number of colonies in the lungs was significantly decreased in sample group than in control group. In animal study with S-180, the life span of AMP treated group was extended than that of control group. IL-12 was effectively increased in AMP treated group in cytokine release assay. Taken together, AMP can be possibly applied to cancer or metastasis.

• Korean Journal of Plant Tissue Culture
• /
• v.25 no.4
• /
• pp.219-223
• /
• 1998

Anthers contanining uninucleate microspores of eight cultivars of pepper were cultured on MS medium supplemented with 0.004mg/L 2,4-D and 0.1mg/L kinetin, 3% sucrose and 0.2% Gelrite, kept at $35^{\circ}C$ for 24 h, and then cultured at $25^{\circ}C$ with a photoperiod of 16 h daylight for 40 days. Frequency of embryoid and callus formation was varied with cultivars. Embryoid formation was found in Cheongyang and Fushimi Amanaga, while callus formation was in California Wonder, Fushimi Amanaga and Geoseong. In anther culture medium supplemented with 1% activated charcoal, embryoid formation was found with 0.5% of frequency only in Cheongyang, while no callus formation was found. In 1/2MS medium, frequency of embryoid formation in Shishitou, Yatsufusa and Taka no Tsume was 1.2%, 0.4% and 0.4%, respectively. On the other hand, in 1/2 B5 medium, frequency of callus formation in Yatsufusa and Taka no Tsume was 2.8% and 2.7%, respectively. Embryoids transferred to hormone-free MS medium were developed to plantlets and acclimatized. The number of chromosomes in the root tip cells of the haploid plant was 2n=$\times$=12 in cv. Cheongyang.

• Journal of Veterinary Clinics
• /
• v.6 no.2
• /
• pp.319-327
• /
• 1989

In order to study the effects of neomycin sulfate on the kidney of Korean black goats after dosing at 36mg/kg(A group) or 18mg/kg of body weight (B group) twice a day, serum chemical values(BUN, SCr), urinary enzyme(GGT) excretion and urinary analysis were checked and renal lesions were observed by light microscope. The proteinuria and granular casts were observed on the 5-6th day and 7th day of treatment with neomycin respectively in the A group. While these changes were observed on the 4th day and the 6th day respectively in one goat of the B group. Urinary GGT excretion began to increase from the 9th day and reached to maximum concentration on the 15th day of treatment with neomycin in the A group. Thereafter, GGT excretion began to decrease and reach to normal level on the 21th day. But GGT excretion increased on the 9th day in only one goat of the B group. Concentrations of BUN and SCr increased on the 12th day in the A group and in one goat of B group. The kidneys were swollen gross pathologically and the renal tubular epithelial cell changes were noticed histologically in the A group and in one goat of the B group. These changes were included degeneration with hyaline droplet formation, flattened epithelial cells and necrotic epithelium. Granular casts were showed in many tubular lumens. Prfesent results indicated that nephrotoxicosis would not occured in Korean black goats dosing with neomycin sulfate less that 36mg/kg of body weight a day.

• KSBB Journal
• /
• v.6 no.3
• /
• pp.289-297
• /
• 1991

The insecticidal protein gene in the pKL-20-1 clone derived from Bacillus thuringiensis serovar. kurstaki plasmid was subcloned in the plant shuttle vector, pGA643. The 7.3 kb fragment was cloned in the BglII and Hpal sites of pGA643 vector and expressed in E. coli S17-1, which produced insecticidal proteins killing Bombyx mori larvae. The clone was named pHL-20. The protoplast formation, calli induction and plantlet regeneration of Nicotiana tabacum was carried out. A tremendous number of mesophyll protoplasts of N. tabacum were formed, up to 7$\times$105 protoplast per ml, for 20 hours in darkness in the enzyme solution of 0.5% cellulase and 0.1% macerosin, pH 5.8. The viabilities of the protoplasts were maintained above 80% for 6 days in the media containing 2mg/1 of NAA and 1mg/1 of kinetin. Calli were induced from the protoplasts and leaves of the N. tabacum on MS medium containing 0.5mg/1 BAP. Under the culture conditions the protoplasts underwent repeated cell division into calli. Plantlets were regenerated from callus cultures derived from protoplast and leaves. Shoots were induced in a medium containing 1mg/1 of BAP.

• International Journal of Oral Biology
• /
• v.41 no.4
• /
• pp.253-262
• /
• 2016

Streptococcus mutans (S. mutans) is one of the most important bacteria in the formation of dental plaque and dental caries. S. mutans adheres to an acquired pellicle formed on the tooth surface, and aggregates with many oral bacteria. It initiates plaque formation by synthesizing glucan from sucrose, which is catalyzed by glucosyltransferases. Propolis is a resinous mixture produced by honeybees, by mixing saliva and beeswax with secretions gathered from wood sap and flower pollen. Bees prevent pathogenic invasions by coating the propolis to the outer and inner surface of the honeycomb. Propolis has traditionally been used for the treatment of allergic rhinitis, asthma and dermatitis. We investigated the inhibitory effects of propolis ethanol extract on biofilm formation and gene expression of S. mutans. The biofilm formation of S. mutans was determined by scanning electron microscopy (SEM) and safranin staining. We observed that the extract of propolis had an inhibitory effect on the formation of S. mutans biofilms at concentrations higher than 0.2 mg/ml. Real-time PCR analysis showed that the gene expression of biofilm formation, such as gbpB, spaP, brpA, relA and vicR of S. mutans, was significantly decreased in a dose dependent manner. The ethanol extract of propolis showed concentration dependent growth inhibition of S. mutans, and significant inhibition of acid production at concentrations of 0.025, 0.05, 0.1 and 0.2 mg/ml, compared to the control group. These results suggest that the ethanol extract of propolis inhibits gene expression related to biofilm formation in S. mutans.