• Restorative Dentistry and Endodontics
• /
• v.26 no.5
• /
• pp.418-435
• /
• 2001

Root canal preparation process is of utmost importance in successful treatment of root canal. Also, one of the most important purpose of the root canal preparation is to enlarge the root canal three dimensionally without changing the curvature of the root canal However as the curvature of the root canal increases, there are many difficulties involved in formation of optimum root canal. Therefore in order to solve the above mentioned problems, new developments in methods of root canal preparation and equipments for such purposes were made. Recently, vigorous studies about newly introduced engine-driven nickel-ti-tanium rotary file are conducted. As shown in research results to dates, it is well established that the use of nickel-titanium file is better suited for curved root canal than stainless steel file in maintaining the curvature or root canal and reducing the deformation of root canal. However it is also acknowledged that there are a few discrepancies in research results according to protocol, due to failure to remove variables in experiments. In addition, although it is recommended by the manufacturer that the GT rotary file should maintain a low rotational speed of 150~350rpm and 'light pressure' as light as not to break the lead of a pencil, academic studies about the vertical force which is not yet standardized are not sufficiently explored. Therefore, this research devised and utilized a special research equipment to standardize the appropriate range of vertical force for GT rotary file through experiments by breaking of the lead of a pencil as expressed by the manufacturer and to accurately measure factors involved through repeating and recreating the environment of root canal preparation. Forming nine experimental groups by varying the vertical forces (150g. 220g, 300g) and rpm (150rpm, 250rpm, 350rpm), the effects of changing vertical forces and rpm on working efficiency were measured in terms of time expended in root canal preparation by crown-down method using a transparent resin block with 35 degree curvature and GT rotary file (z-test). The following research using this special research equipment that involved nine experimental groups and varying the vertical force for root canal preparation from 300g which is within the normal vertical force range to 700g and 1000g which fall outside the normal rpm range. The results were as follows : 1. Analysis of the experiment results revealed that the time spent in root canal preparation decreased as the vertical forces and rpm increased (p<0.05). Also, the effects of rpm were greater than those of the vertical forces within the normal vertical force range ($\beta$-weight test). 2. Observation of the deformation of GT rotary file revealed that deformation increases in a direct correlation with the vertical force increase and in a reverse correlation with the rpm decrease. In the case of the vertical forces close to the normal range, the probability of GT rotary file deformation were quite different depending on the rpm changes. In the case of greater vertical forces, the occurrences of deformation of the file were more frequent regardless of the rpm changes. 3. Deformation and breakage of file were also commonly observed in the expended time measurement experiments and GT rotary file deformation experiments in which low speed rpm (150rpm) was used and at the curved portion of the resin block.

• 한국생물공학회:학술대회논문집
• /
• 2003.04a
• /
• pp.149-152
• /
• 2003

This experiment was carried out to obtain the optimal liquid culture conditions for the mycelial growth and the polysaccharide production of Tricholoma matsutake. For the mycelial growth and polysaccharide production, the synthetic medium was optimized with containing glucose 40 g/L, yeast extract 30 g/L, $KH_2PO_4$ 1.5 g/L and $MgSO_4.7H_2O$ 1 g/L. The effects of agitation and aeration were investigated for the cell growth and the polysaccharide production in batch culture. The biomass and polysaccharide concentrations were 21.87 g/L at 150 rpm and 8.86 g/L at 300 rpm, respectively. And the biomass concentration and the polysaccharide production were 20.85 g/L at 0.5 vvm and 8.83 g/L at 1.5 vvm, respectively.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.11 no.2
• /
• pp.168-172
• /
• 2006

In this study. the transcriptional features of a 2.8 kb region spanning the sigH and rplA genes of Bacillus subtilis were clarified using synthetic oligonucleotides complementary to the transcripts of the rpmG, secE, nusG, and rplK genes. The 5' ends of three transcripts corresponding to this region were located and mapped on the chromosome via primer extension analysis. Three regions, designated Prg, Pn, and Prk, which partially share the consensus sequence recognized by ${\sigma}^A$ RNA polymerase, were theorized to function as promoter elements. The rpmG and secE genes of B. subtilis were cotranscribed from the designated prg promoter, whereas the nusG and rplK genes were transcribed separately from the Pn and Prk promoters, respectively. Accordingly, the transcriptional features, as well as the gene organization, of the region encompassing the sigH and rplA genes of B. subtilis, including the rpmG-secE-nusG-rplK genes, were determined to be distinct from those of Escherichia coli. Divergences in terms of gene organization and transcriptional features within the relevant region would serve as excellent criteria for the delineation of phylogenetic relationships among bacteria.

• KSBB Journal
• /
• v.17 no.3
• /
• pp.228-234
• /
• 2002

Acetobacter xylinum KJ1 efficiently producing bacterial cellulose(BC) In shaking culture was isolated from a rotten grape. The strain was used to investigate optimum operating conditions for increasing BC production and factorial design model was employed for the optimization. The results of experiments were statistically analyzed by SAS program. Reciprocal effects of each factors(carbon source concentration, shaking speeds(rpm), oxygen pressure, and CSL concentration) and culture condition of BC production were examined by getting regression equation of the dependent variable. Comparisons between experimental results and predicted results about BC concentration were done in total 24 experiments by combination of each factors using SAS program, and the correlation coefficients of BC concentration and BC yield were 0.91 and 0.81, respectively. The agitated cultures were peformed in various operation conditions of factors which affected considerably to BC production in jar fermentor. The results showed that BC concentration was 11.67 g/L in 80 hours cultivation under the condition of carbon source concentration : shaking speeds(rpm) : oxygen pressure : CSL concentration : 4% : 460 rpm : 0.28 : 6%. On the other hand BC yield was 0.42 g/g in 80 hours cultivation under the condition of carbon source concentration : shaking speeds(rpm) : oxygen pressure : CSL concentration : 4% : 564 rpm : 0.21 : 2%. The BC production could be enhanced up to more than 2.4 times by factorial design. The result of a verifying experiment under the optimal conditions determined by the factorial design to the BC production showed that the model was appropriate by obtaining BC concentration of 11.47 g/L in the optimum condition.

• 한국생물공학회:학술대회논문집
• /
• 2001.11a
• /
• pp.434-437
• /
• 2001

Shaking cultivation was carried out in 250 mL Erlenmeyel' flasks containing 60 mL of culture solution for 7 days. Artificial seawater was used as a basal culture medium. The cultivation was performed under the conditions that the temperature ranged from $4^{\circ}C$ to $32^{\circ}C$, the agitation speed 50 rpm to 200 rpm, and the sugar concentration 5 g/L to 35 g/L. The medium condition was cultured that sugar and nitrogen ratio 1.25 to 10. The biomass. the lipid content in biomass, and the DBA content of lipid were investigated according to the cultivation conditions. The lipid in biomass was distributed between 10 and 349'0, the DHA in lipid 34% to 43% of the lipid. and the biomass concentration 0.425 g/L to 4.50 g/L.

• Asian-Australasian Journal of Animal Sciences
• /
• v.26 no.11
• /
• pp.1583-1591
• /
• 2013

The objective of this study was to investigate microbial population in the rumen of dairy steers as influenced by supplementing with dietary condensed tannins and saponins and different roughage to concentrate ratios. Four, rumen fistulated dairy steers (Bos indicus) were used in a $2{\times}2$ factorial arrangement in a $4{\times}4$ Latin square design. The main factors were two roughage to concentrate ratios (R:C, 60:40 and 40:60) and two supplementations of rain tree pod meal (RPM) (0 and 60 g/kg of total DM intake). Chopped 30 g/kg urea treated rice straw was used as a roughage source. All animals received feed according to respective R:C ratios at 25 g/kg body weight. The RPM contained crude tannins and saponins at 84 and 143 g/kg of DM, respectively. It was found that ruminal pH decreased while ruminal temperature increased by a higher concentrate ratio (R:C 40:60) (p<0.05). In contrast, total bacterial, Ruminococus albus and viable proteolytic bacteria were not affected by dietary supplementation. Numbers of fungi, cellulolytic bacteria, Fibrobactor succinogenes and Ruminococus flavefaciens were higher while amylolytic bacteria was lower when steers were fed at 400 g/kg of concentrate. The population of Fibrobactor succinogenes, was found to be higher with RPM supplementation. In addition, the use of real-time PCR technique indicated that the population of protozoa and methanogens were decreased (p<0.05) with supplementation of RPM and with an increasing concentrate ratio. Supplementation of RPM and feeding different concentrate ratios resulted in changing the rumen microbes especially, when the animals were fed at 600 g/kg of concentrate and supplemented with RPM which significantly reduced the protozoa and methanogens population.

• 한국생물공학회:학술대회논문집
• /
• 2003.04a
• /
• pp.236-239
• /
• 2003

Erinacine which is produced from Hericium erinaceus mycelia is known to have a stimulating activity of nerve growth factor(NGF) synthesis. Thus, this work was concentrated on the maximum production of Hericium erinaceus mycelia. In order to maximize cell growth, the cultivation was performed with varying the agitation rate and applying the additional medium. As the results, the mycelium concentration was 24.2g/L.

• KSBB Journal
• /
• v.21 no.6 s.101
• /
• pp.493-497
• /
• 2006

Two stage fermentations of glucose/xylose mixture which is similar composition with rice straw hemicellulose hydrolysate were performed by Candida mogii ATCC 18364. In first stage, glucose was consumed rapidly for cell growth in aerobic condition (2 vvm, 300 rpm), then D-xylose was used for xylitol production in semi-aerobic condition (1 vvm, 300 rpm). After 4 days of fermentation, about $24\;g/{\ell}$ xylitol was produced with a yield of 0.58 g/g and volumetric productivity of $0.25\;g/{\ell}{\cdot}h$. To improve the xylitol yield by reduction of xylose consumption for cell growth and maintenance, D-glucose was continuously supplemented during the second stage of fermentation. By D-glucose feeding of $6.8\;g/{\ell}{\cdot}$ day, xylitol was produced up to $29\;g/{\ell}$ with a yield of 0.8 g/g and volumetric productivity $0.30\;g/{\ell}{\cdot}h$ which are 1.2-1.3 times higher than those obtained without D-glucose feeding.

• KSBB Journal
• /
• v.19 no.1
• /
• pp.78-82
• /
• 2004

Experiments were carried out to select an organic nitrogen source and optimize the culture conditions for the production of arachidonic acid by Mortierella alpina DSA-12. Corn steep powder(CSP) was selected as an organic nitrogen source based on arachidonic acid production and raw material price. The optimum C/N ratio was in the range of 15 to 17 with the medium containing glucose as carbon source and CSP as nitrogen source. The optimum culture conditions for arachidonic acid production showed 500 rpm agitation and 25$^{\circ}C$ culture temperature at 0.5 vvm aeration. Under the optimum conditions, the concentration of cell, total lipid and arachidonic acid were 21.8 g/L, 10.2 g/L and 3.70 g/L, respectively, from 50 g/L glucose and 18 g/L CSP. In the 500 L fermenter with 0.5 vvm aeration and 200 rpm agitation, the concentration of cell, total lipid and arachidonic acid were 19.8 g/L, 9.1 g/L and 3.67 g/L, respectively, from 50 g/L glucose and 18 g/L CSP. This result showed that an arachidonic acid production could be possible with a bench-scale fermenter using corn steep powder as a nitrogen source.

• Journal of Life Science
• /
• v.20 no.6
• /
• pp.811-818
• /
• 2010

Optimal agitation speed and aeration rate for the production of gellan by Sphingomnas paucibilis NK2000 in a 7 l bioreactor were found to be 400 rpm and 1.0 vvm. The best time for glucose feeding into the medium for enhanced production of gellan by S. paucibilis NK2000 was 36 hr after cultivation. The concentrations of gellan produced by S. paucibilis NK2000 from 1) 20.0 g/l glucose without additional feeding, 2) 20.0 g/l glucose with feeding of 200.0 g/l glucose at 36 hr, in which the final concentration in the medium was 10.0 g/l, 3) 20 g/l glucose with feeding of 200.0 g/l glucose and a shift in an agitation speed from 400 to 600 rpm, 4) 20.0 g/l glucose with feeding of 200.0 g/l glucose at 36 hr and shifts in an agitation speed from 400 to 600 rpm and an aeration rate from 1.0 to 1.5 vvm, 5) and 20.0 g/l glucose with feeding of 200.0 g/l glucose at 36 hr and shifts in an agitation speed from 400 to 600 rpm and an aeration rate from 1.0 to 2.0 vvm, were 5.19, 5.74, 6.73, 7.93, and 9.40 g/l, respectively, and their conversion rates from glucose were 26.0, 19.1, 22.4, 26.4, and 31.3%, respectively. Compared to those developed using a normal process, production of gellan by S. paucibilis NK2000 from 20.0 g/l glucose was 1.81 times higher, and and its conversion rate was 1.20 times higher when the optimized process developed in this study was used.