• Proceedings of the Plant Resources Society of Korea Conference
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• 2021.04a
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• pp.36-36
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• 2021

Cryopreservation has been broadly used as an efficient method for a long-term conservation for many types of plants especially vegetatively propagated plants. Among several cryopreservation methods, a droplet-vitrification was the most widely applicable and efficient method. Studies have developed protocols for strawberry using droplet-vitrification method and suggested the practical use of the protocol for large number of germplasm with a little modification. In this study, the droplet vitrification method of shoot tip has been tested on 31 accessions provided around the world. Shoot tips were precultured on Murashige and Skoog (MS) liquid medium supplemented with 0.3~0.5M sucrose. Precultured explants were osmoprotected with loading solution, 35% of PVS3 (C4, 17.5% glycerol and 17.5% sucrose) for 40 min and exposed to dehydration solution, PVS3 (B1, 50% glycerol and 50% sucrose) for 60 min. Then, the explants were transferred onto droplets containing 2.5 uL PVS3 on sterilized aluminum foils prior to direct immersion in liquid nitrogen (LN) for 1hr. The cryopreserved shoot tips were rapidly warmed in a water bath at 40C and then unloaded in MS with 0.8M sucrose for 40 min. The shoot tips were cultured in NH₄NO₃-free MS post culture medium for 2 weeks. Subsequently, the explants were moved to the MS medium for 6 weeks and evaluated the regrowth rate. By this droplet-vitrification protocol, twenty-four accessions showed at least 40% regrowth rate. Out of 24 accessions, 'Nonsan1ho' had the highest regeneration rate of 85.8% and 'Jumbo pureberry' had the lowest with 42.1%.

• Korean Journal of Plant Resources
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• v.31 no.6
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• pp.675-683
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• 2018

This study describes an efficient and widely applicable droplet-vitrification following cryopreservation for shoot tips of Chrysanthemum morifolium (Ramat.) cvs. 'Borami' and 'Yes morning'. The shoot tips of Chrysanthemum were precultured in Murashige and Skoog (MS) liquid medium supplemented with sucrose (0.3-0.7 M). Precultured explants were treated with loading solution (LS, C6) containing glycerol 20% and sucrose 20% for 30 min and exposed to dehydration solution (B5) containing 40% of glycerol and 40% of sucrose for 60 min at $25^{\circ}C$, and then transferred onto droplets containing $2.5{\mu}l$ PVS3 on sterilized aluminum foils ($4cm{\times}0.5cm$) prior to direct immersion in liquid nitrogen (LN) for 1 h. The highest regeneration rate (%) was obtained when shoot tips were precultured with treatment-2 (exposing of shoot tips to MS + 0.3M sucrose for 30 h and then treated with MS+0.5 M sucrose for 16 h) at $25^{\circ}C$ in both the cultivars. The viability of cooled samples, followed by culturing on $NH_4NO_3$-free MS medium for first 5 days was increased to two-fold (80.7%) regrowth rate over those cultured on normal MS medium or MS medium containing plant growth regulators. This result shows droplet-vitrification would be a promising method for cryobanking chrysanthemum germplasm.

• Journal of Plant Biotechnology
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• v.8 no.1
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• pp.43-50
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• 2006

The goal of this research was to develop an efficient cryopreservation protocol for germplasms of yam (Diosorea batatas), that were cultivated in Korea. Comparative studies with four other cryogenic techniques and subsequent experiments for shoot regrowth were conducted. in vitro-grown shoot-apices of the D. batatas were successfully cryopreserved by encapsulation-dehydration. The maximum survival of shoot-apices could be achieved when the precultured (with 0.3 M of sucrose for one day) and encapsulated (with a 3%(w/v) Na-alginate solution) apices were dehydrated for $3.5{\sim}4\;h$ prior to direct immersion in LN (liquid nitrogen). The frequency of regrowth rate of cryopreserved apices was not decreased during 3-month storage period. The thawing method markedly affected survival of the cryopreserved apices, and thawing at $40^{\circ}C$ for 3 min produced the best results. When cryopreserved apices were post-cultured on the post-culture medium (MS), supplemented with $0.2mgl^{-1}$ of BA ($N_6$-benzyladenine) and $0.2mgl^{-1}$ of kinetin, they showed direct shooting without callusing.

• The Journal of the Korean dental association
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• v.25 no.5 s.216
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• pp.465-477
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• 1987

This is an experimental and clinical study on the use of an autogenous frozen mandibular bone. Two aspects must be considered in the treatment of mandibular tumors: the eradication of the disease, and the maintenamce of the mandibular continuity for a good functional and esthetic results. The authors used the cryosurgical method in the dogs and the tumor of the mandible in human, which consists of partial mandibular resection; immersion of the bone in the liquid nitrogen at -196℃, followed by reimplantation of the mandibular bone in its bed. In experimental study, the mandibular segment showed favorable healing process without rejection during the cohole experimental periods. In clinical study, the frozen bone showed no antigenicity and excellent cosmetic results.

• Korean Journal of Plant Resources
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• v.32 no.6
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• pp.689-697
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• 2019

This study describes an efficient and widely applicable droplet-vitrification following cryopreservation for shoot tips of strawberry (Fragaria × ananassa Duch.) cvs. 'Wonkyo3114' and 'Gurumi40'. The shoot tips were precultured in Murashige and Skoog (MS) liquid medium supplemented with sucrose (0.3-0.5M). Precultured explants were osmoprotected with loading solution (LS, C4) containing 20% glycerol and 20% sucrose for 40 min and exposed to dehydration solution (B5) containing 40% glycerol and 40% sucrose for 40 min at 25℃, Subsequently, the explants were transferred onto droplets containing 2.5 μL PVS3 on sterilized aluminum foils (4 cm × 0.5 cm) prior to direct immersion in liquid nitrogen (LN) for 1 h. The highest regrowth rate (%) in both the cultivars was obtained when the shoot tips were precultured with MS + 0.3M sucrose for 40 h at 25℃. The cryopreserved shoots tips exhibited 55% regrowth rate by culturing in NH₄NO₃-free MS medium supplemented with 3% sucrose, 1.0 g/L casein, 1.0 mg/L GA₃, and 0.5 mg/L BA for 5 weeks and in MS medium supplemented with 0.5 mg/L GA₃ for 8 weeks. This result shows that droplet-vitrification could be employed as a promising method for cryostorage of strawberry germplasm.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.04a
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• pp.80-80
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• 2019

This study describes an efficient and widely applicable droplet-vitrification following cryopreservation for shoot tips of (Fragaria x ananassa DUCH. cvs. 'Derunoka' and 'Jumbo pure berry'. The shoot tips of strawberry were precultured in Murashige and Skoog (MS) liquid medium supplemented with sucrose (0.3-0.7M). Precultured explants were treated with loading solution (LS, C4) containing glycerol 17.5% and sucrose 17.5% for 40 min and exposed to dehydration solution (B1) containing 50% of glycerol and 50% of sucrose for 60 min at $25^{\circ}C$, and then transferred onto droplets containing $2.5{\mu}l$ PVS3 on sterilized aluminum foils ($4cm{\times}0.5cm$) prior to direct immersion in liquid nitrogen (LN) for 1 h. The highest regeneration rate (%) was obtained when shoot tips were precultured with treatment-2 (exposing of shoot tips to MS + 0.3M Sucrose for 30 h and then treated with MS+0.5 M sucrose for 16 h) at $25^{\circ}C$ in both the cultivars. The viability of cooled samples, followed by culturing on MS medium for 4 weeks was 77.8% and 60.0% for 'Derunoka' and 'Jumbo pure berry', respectively. This result shows droplet-vitrification would be a promising method for cryobanking strawberry germplasm.

• Korean Journal of Plant Resources
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• v.31 no.6
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• pp.684-694
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• 2018

This study describes the successful establishment of a cryopreservation protocol for Citrus limon cultivars: 'Frost Eureka limon' and 'Cook Eureka limon', using a droplet-vitrification method. The shoot tips that were excised from in vitro grown seedlings of the two cultivars were preserved in liquid nitrogen (LN) and successfully regenerated into whole plants. Excised shoot tips were pre-cultured for 1 or 2 days in 0.3 M and 0.5 M sucrose solutions at $25^{\circ}C$ and incubated in a loading solution (LS) composed of 17.5% glycerol + 17.5% sucrose in Murashige and Skoog (MS) medium for 40 min at $25^{\circ}C$. Prior to direct immersion in LN for 1 h, the shoot tips were dehydrated with plant vitrification solution 2 (PVS2) at $0^{\circ}C$ or PVS3 at $25^{\circ}C$. The frozen shoot tips were re-warmed and unloaded with 1.2 M sucrose in $\text\tiny{^1/_2}$ MS for 30 min at $25^{\circ}C$. Shoot tips were post-cultured overnight on survival medium and then micrografted onto 'trifoliate orange' (Poncirus trifoliate (L.) Raf. seedling rootstocks for recovery and to produce whole plants. The highest regrowth rates were 53.5% and 50.3% for cryopreserved shoot tips of 'Frost Eureka limon' and 'Cook Eureka limon', respectively, when pre-cultured in 0.3 M and 0.5 M sucrose concentrations in a sequencing manner, with LS and treated with PVS2 for 60 min at $0^{\circ}C$. We also investigated whether the ammonium ion concentration on post-culture medium affected the viability of the cryopreserved Citrus shoot tips. The viability of cooled samples, following culturing on woody plant media (WPM) containing $\text\tiny{^1/_4}$ ammonium nitrate overnight before micrografting, was the highest (70.3%) in 'Frost Eureka limon'. The study described here is a cost-effective and safe method to conserve Citrus fruit cultivars, for the improvement and large-scale multiplication of fruit plants and for breeding disease resistance.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.1
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• pp.5-14
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• 2003

Principles of a novel pulse growing method are described. The method realized in the crystal growing on a seed from melts under raw melt feeding provided a more reliable control of the crystallization process when producing large alkali halide crystals. The slow natural convection of the melt in the crucible at a constant melt level is intensified by rotating the crucible, while the crystal rotation favors a more symmetrical distribution of thermal stresses over the crystal cross-section. Optimum rotation parameters for the crucible and crystal have been determined. The spatial position oi the solid/liquid phase interface relatively to the melt surface, heaters and the crucible elements are considered. Basing on that consideration, a novel criterion is stated, that is, the immersion extent of the crystallization front (CF) convex toward the melt. When the crystal grows at a <> CF immersion, the raised CF may tear off from the melt partially or completely due to its weight. This results in avoid formation in the crystal. Experimental data on the radial crystal growth speed are discussed. This speed defines the formation of a gas phase layer at the crystal surface. The layer thickness il a function of time a temperature at specific values of pressure in the furnace and the free melt surface dimensions in the gap between the crystal and crucible wall. Analytical expressions have been derived for the impurity component mass transfer at the steady-state growth stage describing two independent processes, the impurity mass transfer along the <> path and its transit along the <> one. The heater (and thus the melt) temperature variation is inherent in any control system. It has been shown that when random temperature changes occur causing its lowering at a rate exceeding $0.5^{\circ}C/min$, a kind of the CF decoration by foreign impurities or by gas bubbles takes place. Short-term temperature changes at one heater or both result in local (i.e., at the front) redistribution of the preset axial growth speed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.5
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• pp.262-267
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• 2009

Superhydrophobic $TiO_2$ thin films were successfully fabricated on a glass substrate by wet process. Layer-by-layer (LBL) deposition and liquid phase deposition (LPD) methods were used to fabricate the thin films of micro-nano complex structure with a high roughness. To fabricate superhydrophobic $TiO_2$ thin films, the (PAH/PAA) thin films were assembled on a glass substrate by LBL method and then $TiO_2$ nanoparticles were deposited on the surface of (PAH/PAA) thin film by LPD method, Subsequently, hydrophobic treatment using fluoroalkyltrimethoxysilane (FAS) was carried out on the surface of prepared $TiO_2$ thin films. The $TiO_2$ thin film fabricated with 45 minutes immersion time on $(PAH/PAA)_{10}$ showed the RMS roughness of 65.6nm, water contact angel of $155^{\circ}$ and high transmittance of above 80% (>650nm in wavelength) after the hydrophobic treatment. The Surface morphologies, optical properties and contact angel of prepared thin films with different experimental conditions were measured by field emission scanning electron microscope (FE-SEM), atomic force microscope (AFM), UV-Vis spectrophotometer and contact angle meter.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.2
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• pp.183-193
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• 2018

Currently, the Korea Atomic Energy Research Institute (KAERI) is planning to build the Ki-Jang Research Reactor (KJRR) in Ki-Jang, Busan. It is important to safely dispose of low-level radioactive waste from the operation of the reactor. The most efficient way to treat radioactive waste is cement solidification. For a radioactive waste disposal facility, cement solidification is performed based on specific waste acceptance criteria such as compressive strength, free-standing water, immersion and leaching tests. Above all, the leaching test is important to final disposal. The leakage of radioactive waste such as $^{137}Cs$ causes not only regional problems but also serious global ones. The cement solidification method is simple, and cheaper than other solidification methods, but has a lower leaching resistance. Thus, this study was focused on the development of cement solidification for an enhancement of cesium leaching resistance. We used Zeolite and Loess to improve the cesium leaching resistance of KJRR cement solidification containing simulated KJRR liquid waste. Based on an SEM-EDS spectrum analysis, we confirmed that Zeolite and Loess successfully isolated KJRR cement solidification. A leaching test was carried out according to the ANS 16.1 test method. The ANS 16.1 test is performed to analyze cesium ion concentration in leachate of KJRR cement for 90 days. Thus, a leaching test was carried out using simulated KJRR liquid waste containing $3000mg{\cdot}L^{-1}$ of cesium for 90 days. KJRR cement solidification with Zeolite and Loess led to cesium leaching resistance values that were 27.90% and 21.08% higher than the control values. In addition, in several tests such as free-standing water, compressive strength, immersion, and leaching tests, all KJRR cement solidification met the waste acceptance or satisfied the waste acceptance criteria for final disposal.