• Korean Chemical Engineering Research
• /
• v.49 no.5
• /
• pp.664-668
• /
• 2011

Spherical alumina precursors represented by $AlO_xCl_y(OH)_z$, 30~200 nm in particle diameter, were prepared by partial hydrolysis of $AlCl_3$ vapor in a 500 ml reactor. Investigated on the particle morphology and size were the effects of the reaction time, the stirring speed and the reaction temperature. The particle morphology and size was insensitive to the reaction time in the range 20 to 300 s. The variation of the stirring speed from 0 to 300 and 800 rpm showed that the particle size was the largest at 0 rpm. As the temperature was varied from 180 to 190, 200, $140^{\circ}C$, the particle size showed a maximum at $190^{\circ}C$. By calcination of the as-produced particles at $1,200^{\circ}C$ for 6h with a heating rate of $10^{\circ}C$/min, ${\alpha}$-alumina particles 45 nm in surface area equivalent diameter were obtained. The particle shape after calcination turned wormlike due to sintering between neighboring particles. A rapid calcination at $1400^{\circ}C$ for 0.5 h with a higher heating rate of $50^{\circ}C$/min reduced the sintering considerably. An addition of $SiCl_4$ or TMCTS(2,4,6,8-tetramethylcyclosiloxane) to the $AlCl_3$ reduced the sintering effectively in the calcination step; however, peaks of ${\gamma}$ or mullite phase appeared. An addition of $AlF_3$ to the particles obtained from the hydrolysis resulted in a hexagonal disc shaped alumina particles.

• Restorative Dentistry and Endodontics
• /
• v.33 no.1
• /
• pp.1-8
• /
• 2008

The purpose of this study was to evaluate the effect of a new resin monomer, filler size and polishing technique on the surface roughness of composite resin restorations using confocal laser scanning microscopy. By adding new methoxylated Bis-GMA (Bis-M-GMA, 2,2-bis[4-(2-methoxy-3-methacryloyloxy propoxy) phenyl] propane) having low viscosity, the content of TEGDMA might be decreased. Three experimental composite resins were made: EX1 (Bis-M-GMA/TEGDMA = 95/5 wt%, 40 nm nanofillers); EX2 (Bis-M-GMA/TEGDMA = 95/5 wt%, 20 nm nanofillers); EX3 (Bis-GMA/TEGDMA = 70/30 wt%, 40 nm nanofillers). Filtek Z250 was used as a reference. Nine specimens (6 mm in diameter and 2 mm in thickness) for each experimental composite resin and Filtek Z250 were fabricated in a teflon mold and assigned to three groups. In Mylar strip group, specimens were left undisturbed. In Sof-lex group, specimens were ground with #1000 SiC paper and polished with Sof-lex discs. In DiaPolisher group, specimens were ground with #1000 SiC paper and polished with DiaPolisher polishing points. The Ra (Average roughness), Rq (Root mean square roughness), Rv (Valley roughness), Rp (Peak roughness), Rc (2D roughness) and Sc (3D roughness) values were determined using confocal laser scanning microscopy. The data were statistically analyzed by Two-way ANOVA and Tukey multiple comparisons test (p = 0.05). The type of composite resin and polishing technique significantly affected the surface roughness of the composite resin restorations (p < 0.001). EX3 showed the smoothest surface compared to the other composite resins (p < 0.05). Mylar strip resulted in smoother surface than other polishing techniques (p < 0.05). Bis-M-GMA. a new resin monomer having low viscosity, might reduce the amount of diluent, but showed adverse effect on the surface roughness of composite resin restorations.

• Journal of Life Science
• /
• v.18 no.2
• /
• pp.167-174
• /
• 2008

Antimicrobial activity of Zanthoxylum piperitum was investigated against Streptococcus mutans that causes dental caries. Although the methylene chloride extract of seeds exhibited higher antimicrobial activity than other organic solvent extracts, including methanol, ethyl acetate, and hexane extracts of pericarps or seeds of Z. piperitum, essential oils prepared from both seeds and pericarps possessed more potent inhibitory activity than the methylene chloride extract of seeds. The minimal inhibitory concentrations (MICs) of the essential oils of seeds and pericarps were 0.3 mg/ml and 4.0 mg/ml against S. mutans, respectively. When the seed essential oil was further separated into seven fractions (CS-SD-A${\sim}$CS-SD-G) by thin layer chromatography (TLC), all fractions exhibited lower antimicrobial activity than the essential oil. To understand the antimicrobial ingredients of Z. piperitum, seeds the gas chromatography-mass spectrometry (GC-MS) data of the methylene chloride extract of seeds was compared with those of the seed essential oil (CS-SD). Whereas the methylene chloride extract of seeds contained carvacrol (0.24%), ${\beta}$-caryophyllene (1.72%), and ${\alpha}$-humulene (0.88%), which were previously known to inhibit growth of S. mutans, the seed essential oil contained sabinene (1.57%), linalool (1.55%), citronellal (13.67%), terpinene-4-ol (0.45%), citronellol (3.69%), geraniol (0.9%), linalyl acetate (1.35%), ${\beta}$-caryophyllene (1.35%), ${\alpha}$-humulene (0.78%), and ${\delta}$-cadinene (0.67%) in this regard. These results indicate that Z. piperitum seeds possess various inhibitory substances against S. mutans, and an effective method to isolate the active ingredients from the seeds is to prepare the essential oil. These results also suggest that the essential oil of Z. piperitium seeds may be applicable to preventing dental caries.

• Korean Journal of Medicinal Crop Science
• /
• v.13 no.3
• /
• pp.93-100
• /
• 2005

This research was performed to investigate the possibilities of industrial usage of camellia (Camellia japonica L.) by examining the antioxidant and antimicrobial effects of methanol extract with different sections. Content of total phenolics, DPPH radical scavenging activities and antibacterial activity of young leaf, mature leaf, flower bud, flower, bark, and seed of camellia were compared in vitro experimental models. Total phenolics was contained the higher in young leaf (74.62 mg), flower bud (65.02 mg) and flower (62.42 mg) but less than 20.95 mg per 100 g of dry weight in other parts of Camellia japonica L. And effects of antioxidant measured by DPPH radical scavenger activity ($RC_{50}$, reduce concentration 50%), was shown higher $7.16{\sim}18.14\;{\mu}g/m{\ell}$ in methanol extract of young leaf, flower bud and flower than $61.23\;{\mu}g/m{\ell}$ of BHT as a chemical oxidant. Also, the antimicrobial activity of Camellia japonica L. extracts determined using a paper disc method against food-borne pathogen and food spoilage bacteria, the young leaves extracts showed the most active antimicrobial activity against 7 kinds of harmful microorganisms. Flower bud extracts showed the highest antibacterial activity against P. aeruginosa and Enterobacter spp. C1036. In addition, the minimum inhibitory concentration (MIC) of young leaf extract against B. subtillis,S. fradiae,S. aureus,E. coli,P. aeruginosa, Enterobacter spp. C1036, and S. typhimurium were revealed 1 to 15 ${\mu}g/m{\ell}$. As a result, antimicrobial activity of camellia extracts was shown higher gram positive bacteria than gram negative bacteria.

• Applied Biological Chemistry
• /
• v.47 no.1
• /
• pp.78-84
• /
• 2004

In order Nuruk to improve the quality of millet wine, a traditional Jeju cereal wine, yeasts and molds were isolated from 35 kinds of Nuruk collected nationwide. Isolated strains were screened for saccharification of starch and brewing of millet wine. Fermentation characteristics of millet wine with different types of Nuruk were also investigated. The average number of microbial populations in the Nuruk were $6.4{\times}10^5{\sim}4.5{\times}10^7\;cfu/g$ for molds and $1.4{\times}10^4{\sim}7.7{\times}10^7\;cfu/g$ for yeasts. Among the 169 strains of molds and 103 strains of yeasts, 16 strains were screened for saccharifying activity on starch as a substrate, and one yeast strain was screened for the brewing of millet wine. A8-3, supposed as Aspergillus sp., showed the highest enzyme activities of glucdamylase, ${\alpha}-amylase$ and xylanase while B23-3 strain, supposed as Rhizopus sp., showed the highest saccharifying activity. A10-4, supposed as Saccharomyces sp., showed the highest level of weight loss from $CO_2$ evolution, sugar and alcohol tolerance during fermentation. When the Nuruk was made after inoculation with the selected strains, saccharifying activity was higher for the co-cultivation of A8-3 and B23-3 than individual cultivation of each strain. Similar saccharifying activities were shown in both disc-type and pellet-type Nuruk. It was suggested that pellet-type Nuruk could improve fermentation yield. The collected Nuruk consisted of $10{\sim}13%$ moisture, $55{\sim}70%$ total sugar, $10{\sim}18%$ crude protein, $0.2{\sim}1.0%$ crude fat and $1.8{\sim}2.1%$ ash. The Nuruk made in this study was composed of $12{\sim}15%$ moisture, $61{\sim}71%$ total sugar, $15{\sim}20%$ crude protein, $0.4{\sim}1.5%$ crude fat and $1.1{\sim}1.5%$ ash.

• Tuberculosis and Respiratory Diseases
• /
• v.58 no.3
• /
• pp.295-298
• /
• 2005

We report a case of a 48-year-old man with a paradoxic upper airway obstruction and central sleep apnea that developed after an anterior cervical spinal fusion. Nine months before being admitted to this hospital, he was diagnosed with a herniated intervertebral disc between the 5th and 6th cervical spine, and the first operation was carried out. Two months later, a pseudoarthrosis has developed and a second operation, an anterior interbody fusion of the C5 and C6 using autogenous strut bone graft, was performed. After the second operation, he began to complain of snoring, excessive daytime sleepiness, insomnia, and a bizarre sound heard near the upper airway during breathing. Nasopharyngoscope and magnetic resonance imaging disclosed a paradoxical narrowing of the nasopharynx during expiration. On the overnight polysomnography, the apnea index was 8.7/h (central apnea, 7.0/h; obstructive apnea, 1.7/h). Nasal continuous positive airway pressure was applied, but he complained of pressure-intolerance, and laser-assisted uvulopalatoplasty was then performed. Two months after surgery, clinical symptoms as well as the apneas had improved markedly. We suggest that this paradoxic upper airway obstruction might be associated with the anterior cervical spinal surgery even though the mechanism is unclear. This case also emphasizes that an upper airway obstruction can contribute to the development of central sleep apnea.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.4 no.4
• /
• pp.113-125
• /
• 1984

Water supply has been mainly dependent on the construction of the dams in Korea. It is difficult, however, to continue to construct dams for many reasons, such as the decrease of construction sites, the increase of construction costs, the compensation of residents in flooded areas, and the environmental effects. Water demands have increased and are expected to continue increasing due to the concentration of people in the cities, the rise of the living standard, and rapid industrial growth. It is acutely important to find countermeasures such as development of ground water, desalination, and recycling of waste water to cope with increasing water demands. Recycling waste water includes all means of supplying non-potable water for their respective usages with proper water quality which is not the same quality as potable water. The usages of the recycled water include toilet flushing, air conditioning, car washing, yard watering, road cleaning, park sprinkling, and fire fighting, etc. Raw water for recycling is obtained from drainage water from buildings, toilets, and cooling towers, treated waste water, polluted rivers, ground water, reinfall, etc. The water quantity must be considered as well as its quality in selecting raw water for the recycling. The types of recycling may be classified roughly into closed recycle systems and open recycle systems, which can be further subdivided into individual recycle systems, regional recycle systems and large scale recycle system. The treatment methods of wastewater combine biochemical and physiochemical methods. The former includes activated sludge treatment, bio-disc treatment, and contact aeration treatment, and the latter contains sedimentation, sand filtration, activated carbon adsorption, ozone treatment, chlorination, and membrane filter. The recycling patterns in other countries were investigated and the effects of the recycling were divided into direct and indirect effects. The problems of water reuse in recycle patterns were also studied. The problems include technological, sanitary, and operational problems as well as cost and legislative ones. The duties of installation and administrative organization, structural standards for reuse of water, maintenance and financial disposal were also studied.

• Korean Journal of Food Science and Technology
• /
• v.41 no.6
• /
• pp.673-680
• /
• 2009

This study was conducted to screen for plant food materials that improve human intestinal microflora, especially microorganisms associated with obesity. Among 30 tested plant food materials, the extract of Schizandra chinensis inactivated Eubacterium limosum, Bacteroides fragilis and Clostridium spp. Additionally, S. chinensis extract was also found to have a growth-promoting effect on Bifidobacterium spp.. The antimicrobial activity and antioxidant activity of the water extract did not decrease in respond to heating. Additionally, the water extract of S. chinensis did not show a toxic effect on the growth of Caco-2 cells. In vivo feeding tests were performed to investigate the influence of extract on the intestinal microflora in rats. Although the extract did not reduce obesity induced by a high fat diet, it led to significant increase in the population of Bifidobacterium spp. and a decrease in the population of Clostridium spp. in rats. Taken together, these results indicate that S. chinensis could be useful as a functional food component to control intestinal microbial flora.

• Horticultural Science & Technology
• /
• v.34 no.4
• /
• pp.537-548
• /
• 2016

The objective of this study was to evaluate the antimicrobial activities of 9 kinds of medicinal plants against crown gall in grapevine. The medicinal plants extracted with several solvent systems were screened for in vitro antibacterial activity by the disc diffusion method. The ethanol and ethyl acetate extracts from magic lily flowers, tachys roots, asian plantain flowers and seeds, sweet wormwood leaves, stems and flowers, immature bitter melon fruits, cockscomb flowers, and peach tree resin showed in vitro antimicrobial activities against Rhizobium vitis with growth inhibition zones ranging from 10 to 27 mm in diameter. The minimum inhibitory concentration values of extracts against R.vitis ranged from 10,000 in Asian plantain flower and 50,000 fold diluted extracts in sweet wormwood flowers, stems, leaves, cockscomb leaves and immature bitter melon fruits. The active fractions of ethyl acetate and ethanol extracts from the medicinal plants were partially separated through silica gel column chromatography and thin layer chromatography (TLC). The active fractions were separated at Rf 0.36, 0.69, 0.75, 0.84, and 0.94 in sweet wormwood extracts, Rf 0.96 and 0.99 in cockscomb flower extracts, Rf 0.92 and 0.97 in cockscomb leaf extracts, and Rf 0.85 in immature bitter melon fruit extracts in TLC analysis developed with hexane:ethyl acetate (20:80, v/v) and methanol:chloroform (20:80, v/v). Among extracts from plants with in vitro antimicrobial activities, sweet wormwood, cockscomb leaves, and immature bitter melon fruits showed in vivo antimicrobial activities with inhibition activity of 100, 67, and 83.3%, respectively, in 'Kyoho' grapevine inoculated with R. vitis compared with the untreated control. These findings indicate that extracts of medicinal plants could be used as sustainable candidates to control crown gall disease caused by R. vitis in grapevines.

• Journal of radiological science and technology
• /
• v.37 no.1
• /
• pp.7-14
• /
• 2014

By using a Chest Phantom(DUKE Phantom) focusing on dose reduction of diagnostic radiation field with the most use of artificial radiation, and attempt to reduce radiation dose studies technical radiation. Publisher of the main user of the X-ray Radiological technologists, Examine the effect of reducing the radiation dose to apply additional filtering of the X-ray generator. In order to understand the organ dose and effective dose by using the PC-Based Monte Carlo Program(PCXMC) Program, the patient receives, was carried out this research. In this experiment, by applying a complex filter using a copper and Al(aluminum,13) and filtered single of using only aluminum with the condition set, and measures the number of the disk of copper indicated by DUKE Phantom. The combination of the composite filtration and filtration of a single number of the disk of the copper is the same, with the PCXMC 2.0. Program looking combination of additional filtration fewest absorbed dose was calculated effective dose and organ dose. Although depends on the use mAs, The 80 kVp AP projection conditions, it is possible to reduce the effective amount of about 84 % from about 30 % to a maximum at least. The 120 kVp PA projection conditions, it is possible to reduce the effective amount of about 71 % from about 41 % to a maximum of at least. The organ dose, dose reduction rate was different in each organ, but it showed a decrease of dose rate of 30 % to up 100 % at least. Additional filtration was used on the imaging conditions throughout the study. There was no change in terms of video quality at low doses. It was found that using the DUKE Phantom and PCXMC 2.0 Program were suitable to calculate the effect of reducing the effective dose and organ dose.