• The Journal of Korean Academy of Prosthodontics
• /
• v.58 no.4
• /
• pp.275-281
• /
• 2020

Purpose: Development of a latent antimicrobial soft liner is strongly needed to overcome a possible inflammation related with its dimensional degrade or surface roughness. Modified tissue conditioner (TC) containing chitosan-doped silver nanoparticles (ChSN) complexes were synthesized and assessed for their characterizations. Materials and methods: ChSN were preliminarily synthesized from silver nitrate (AgNO₃), sodium borohydride (NaBH₄) as a reducing agent and chitosan biopolymer as a capping agent. Ultraviolet-visible and Fourier transform infrared spectroscopy were conducted to confirm the stable reduction of nanoparticles with chitosan. Modified TC blended with ChSN by 0 (control), 1.0, 3.0 and 5.0 % mass fraction were mechanically tested by ultimate tensile strength (UTS), silver ion elution and color stability (n=7). Results: At 24 hour and 7 day storage periods, UTS values were not significant (P>.05) as compared with pristine TC (control) and silver ion was detected with the dose-dependent values of ChSN incorporated. Color stability of TC were influenced by ChSN add, with the higher doses, the significantly greater color changes (P<.05). Conclusion: A stable synthesized ChSN was acquired and modified TC loading ChSN was characterized as silver ion releasing without detrimental physical property. For its clinical application, antimicrobial test, color control and multifactor investigations are still required.

• Journal of Plant Biotechnology
• /
• v.36 no.1
• /
• pp.81-86
• /
• 2009

An efficient and reproducible plant regeneration system was established using transverse thin cell layers (tTCLs) in five cultivars of Brassjca juncea L. The effects of medium conditions, explant types (tTCLs of hypcotyl and cotyledonary petiole) on shoot regeneration were examined in this study. The maximum shoot regeneration frequency was obtained in Murashige and Skoog (MS) medium supplemented with 4 mg/L 6-benzylaminopurine (BA) and 0.2 mg/L 1-naphthaleneacetic acid (NAA). The hypocotyls derived tTCL explants had more shoot regeneration frequency (52%) than the cotyledonary petiole derived tTCL explants. Shoot induction was further improved by the addition of silver nitrate ($AgNO_3$) in the regeneration medium. A significant genotypic effect was also observed between the five cultivars; Rai-5 displayed higher capacities to produce shoots than other cultivars. Regenerated shoots were rooted on MS basal medium without PGRs which induced 90% of roots. The plantlets established in greenhouse conditions with 99% survival, flowered normally and set seeds. The regenerated plants were fertile and identical to source plants.

• Journal of Powder Materials
• /
• v.19 no.1
• /
• pp.60-66
• /
• 2012

In this study, Platinum(Pt) nanoparticles were synthesized by using polyol process which is one of the liquid phase reduction methods. Dihydrogen hexachloroplatinate (IV) hexahydrate $(H_2PtCl_6{\cdot}6H_2O)$, as a precursor, was dissolved in ethylene glycol and silver nitrate ($AgNO_3$) was added as metal salt for shape control of Pt particle. Also, polyvinylpyrrolidone (PVP), as capping agent, was added to reduce the size of particle and to separate the particles. The size of Pt nanoparticles was evaluated particle size analyzer (PSA). The size and morphology of Pt nanoparticles were observed by transmission electron microscopy (TEM) and high resolution TEM (HRTEM). Synthesized Pt nanoparticles were studied with varying time and temperature of polyol process. Pt nanoparticles have been successfully synthesized with controlled sizes in the range 5-10 and 20-40 nm with cube and multiple-cube shapes.

• Korean Journal of Agricultural Science
• /
• v.9 no.2
• /
• pp.484-493
• /
• 1982

This study was conducted to clarify the effects of daminozide (butanedioic acid mono-(2,2 - dimethylhydrazide)) sprayed 2 days be fore harvest and floral preservative solutions on longevity, quality and ethylene production of 'Georgia' cut lily for prolonging vase life and improving quality of cut lily flowers. And also the relation between ethylene production and flower senescence of cut lily was studied. 1. Lilies held in silver nitrate ($AgNO_3$) at 25 and 50 ppm were increased in solution uptake, fresh weight, and flower longevity. The solution of 2.5% sucrose+50 ppm $AgNO_3$+200 ppm aluminum sulfate+10 ppm 6-benzylamino purine prolonged vase life and improved quality of cut lily flowers. 2. Lilies sprayed with 500 ppm daminozide 2 days be fore harvest and then held in the preservative solution (5% sucrose+50 ppm $AgNO_3$+150ppm 8-hydroxyquinoline) after harvest were significantly increased in fresh weight and vase life as compared with non-sprayed (control) flowers. 3. Ethylene production from cut lily was increased by ethephon ((2-chloroethyl) phosphonic acid) treatment. The flowers producing a lot of ethylene, however, were senesced slowly instead of rapid wilting. 4. The preservative solution markedly reduced ethylene production of cut lily but prolonged vase life for only a few days. 5. These results suggest that ethylene be one of the most important factors promoting flower senescence of cut lily, but it be very difficult to prolong vase life remarkably by only inhibition of ethylene production in cut lily.

• Korean Journal of Plant Tissue Culture
• /
• v.25 no.4
• /
• pp.251-256
• /
• 1998

The effect of several factors on efficiency of anther culture of broccoli was studied. The medium supplemented with 14% sucrose, 125mg/L of silver nitrate and 0.1mg/L of each of NAA and 2,4-D was best in embryogenesis in all varieties tested. The effect of auxin was affected by silver nitrate, that is, it lowered embryogenesis when the concentration of NAA and 2,4-D was low, but it enhanced when their concentrations were high. Benzyl aminopurine increased embryogenesis in some varieties, but decreased in others. Although microspore embryogenesis was observed in anthers of which heigest was 1 to 0.6 - 1.0 of petal heigest in the bud, which corresponds to the early uninucleate to early binucleate stage of the microspores, it was much better when the ratio of heigest was 1 : 0.8. More embryos ware inducted from culture in March than in February in general. Because there was a big yearly variation, it was assumed that microspore embryogenesis was influenced greatly by the culture condition and the physiological condition of donor plants.

• Plant Biotechnology Reports
• /
• v.4 no.4
• /
• pp.321-328
• /
• 2010

An efficient protocol for in vitro organogenesis was achieved from callus-derived immature and mature leaf explants of Momordica charantia, a very important vegetable and medicinal plant. Calluses were induced from immature leaf explants excised from in vitro (15-day-old seedlings) mature leaf explants of vivo plants (45 days old). The explants were grown on Murashige and Skoog (MS) medium with Gamborg (B5) vitamins containing 30 g $1^{-1}$ sucrose, 2.2 g $1^{-1}$ Gelrite, and 7.7 lM naphthalene acetic acid (NAA) with 2.2 ${\mu}M$ thidiazuron (TDZ). Regeneration of adventitious shoots from callus (30-40 shoots per explant) was achieved on MS medium containing 5.5 ${\mu}M$ TDZ, 2.2 ${\mu}M$ NAA, and 3.3 ${\mu}M$ silver nitrate ($AgNO_3$). The shoots (1.0 cm length) were excised from callus and elongated in MS medium fortified with 3.5 ${\mu}M$ gibberellic acid ($GA_3$). The elongated shoots were rooted in MS medium supplemented with 4.0 ${\mu}M$ indole 3-butyric acid (IBA). Rooted plants were acclimatized in the greenhouse and subsequently established in soil with a survival rate of 90%. This protocol yielded an average of 40 plants per leaf explant with a culture period of 98 days.

• Journal of Korean Society of Forest Science
• /
• v.84 no.1
• /
• pp.41-47
• /
• 1995

A micropropagation system for black Locust(Robinia pseudoacacia) was established by using shoots and pin-punctured leaves of in vitro germinated seedlings. The greatest number of shoots (an average of 10.5 shoots) was obtained when shoot tips were cultured on MS medium supplemented with 1.0 mg/l BAP and 0.01 mg/l NAA. When pin-punctured leaf explants were cultured on the same medium, mean number of 13.5 shoots were produced. Shoot growth was accelerated by adding 50 mg/l of silver nitrate ($AgNO_3$), an anti-ethylene compound to the culture medium. Each shoot was excised from the mass and transferred onto half strength MS medium for rooting. Zygotic embryos at different developmental stages were cultured on LS medium supplemented with various growth regulators to induce somatic embryos. When cultured on LS medium with 1.0 mg/l 2,4-D. 14.3% of the zygotic embryos induced somatic embryos. Upon transfer onto the basal medium, somatic embryos sporadically converted into plantlets.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.9 no.3
• /
• pp.185-193
• /
• 1976

The sterol compositions of the Pelecypoda, M. sultataria, S. sachalinensis, and the Gastropoda, H. discus hannai Inc, T. cornutus were investigated. The results areas follows: 1. The contents of the unsaponifiables and sterols of the Pelecypoda, M. sulcataria, S. sathalinensis, and the Gastropoda, H. discus hannai Ino, T. cornutus, are $12.0\%,\;11.8\%,\;and\;16.2\%,\;15.3\%$, respectively. 2. The complex sterols from the Pelecypoda and Gastropoda are well separated on Silica Gel HF 254 TLC impregnated with $15\%$ silver nitrate. 3. The prominent sterols of the Pelecypoda, M. sulcateria and S. sachalinensis, are 22-trans-24-norcholesta-5, $22-dien-3\beta-ol$ $3.0\%\;3.9\%$ 22-dehydrocholesterol $6.7\%,\;10.2\%$, cholesterol $39.0\%,\;48.6\%$ brassicasterol $14.1\%,\;13.8\%$ 24-methylenecholesterol $19.4\%,\;11.5\%$, stigmasterol $2.4\%,\;0\%$ $\beta-sitosterol\;10.5\%,\;11.9\%$, and fucosterol $4.3\%,\;0\%$. 4. Abalone, H. discus hannai Ino, and T. cornutus contain cholesterol $98.0\%,=97.5\% as main component with small amounts of 22-dehydrocholesterol, brassicasterol and desmosterol. In H. discus hannai rno, 24-methylenecholesterot and fucosterol are also found.

• Analytical Science and Technology
• /
• v.17 no.5
• /
• pp.381-387
• /
• 2004

To characterize chemically a spent pressurized water reactor (PWR) fuel, an analytical method for trace amounts of tritium ($^3H$) in it has been established. Considering the effective management of radioactive wastes generated through the whole experimental process and the radiological safety for analysts, a separation condition under which $^{14}C$ and $^3H$ can be sequentially recovered from a single fuel sample was optimized using simulated spent PWR fuel dissolved solutions. $^{14}CO_2$ evolved during dissolution of the spent PWR fuels with nitric acid was trapped in an aliquot of 1.5 M NaOH. $^{129}I_2$ which was volatilized along with $^{14}CO_2$ was removed using a silver nitrate-impregnated silica gel absorbent. $^3H$ remaining in the fuel dissolved solution as $^3H_2O$ was selectively recovered by distillation. Its recovery yield was 97.9% with a relative standard deviation of 0.9% (n=3). $^3H$ in a spent PWR fuel with burnup value of 37,000 MWd/MtU was analyzed, reliability of this analytical method being evaluated by standard addition method.

• Analytical Science and Technology
• /
• v.12 no.4
• /
• pp.290-298
• /
• 1999

A study on the application of impedance phase angle for redox titration, acid-base titration, chelate titration and precipitation titration has been carried out. A constant alternating current was passed between two platinum electrodes. One of them was a polarizable micro-electrode of $0.1cm^2$ or $0.026cm^2$ surface area and the other a non-polarizable large electrode of $1cm^2$ surface area dipped in the solution to be titrated. The impedance and the phase angle of the titration cell were measured with lock-in amplifier to obtain well behaved titration curve respectively. In titration of oxalic acid vs. potassium permanganate, the end-point was obtained successfully from the phase angle titration curve. In this experiment, the concentration of 0.0005 M to 0.05 M, the current of $50{\mu}A$ and the frequency of near 50 Hz were used. In titration of phosphoric acid vs. sodium hydroxide, the first end-point was obtained successfully on the optimum experimental condition of 0.001 M concentration, $50{\mu}A$ current and 25~97 Hz frequency. However, the end-point in titration of cupric sulfate vs. disodium-EDTA couldn't be obtained clearly. The end-point was obtained with the out-of-phase impedance curve on the experimental condition of 0.01 M concentration, $100{\mu}A$ current, 5~35 Hz frequency range. In titration of sodium chloride vs. silver nitrate, the end-point was obtained successfully on the experimental condition of 0.1 M concentration, $100{\mu}A$ current and 5~47 Hz frequency range. This study showed that the impedance phase angle was applicable for the detection of the end-points in redox titration curve, acid-base titration curve, chelate titration curve and precipitation titration curve.