• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.3
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• pp.113-116
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• 2010

We report on the growth and characteristics of the structural and optical properties of InGaN nano-structures doped with antimony (Sb) as a catalyst. The use of catalyst has been explored to modify the growth and defect generation during strained layer heteroepitaxial growth. We performed the growth of the InGaN nano-structures on c-sapphire substrates using mixed-source hydride vapor phase epitaxy (HVPE). The characteristic of samples was measured by scanning electron microscope (SEM) and photoluminescence (PL). The aligning direction of c-axis of the InGaN nano-structures was changed from vertical to parallel or inclined to the surface of substrates when the Sb was added as a catalyst. The indium composition was estimated about 3.2% in both cases of with or without the addition of Sb in the InxGal-xN structures. From the results of InGaN nano-structures formed with the addition of Sb, we can expect the performance of optical devices would be more improved by reduced piezo-electric field if we use the InGaN nano-structures of which c-axes are aligned parallel to the substrates as an active layer.

• Journal of Bio-Environment Control
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• v.16 no.2
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• pp.108-114
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• 2007

This study was conducted to clarify the effects of the different mixing ratios of substrate mixtures based on peat moss and the concentration of nutrient solution on the growth of tomato (Lycopersicon esculentum Mill.) seedlings. Substrates such as peat moss, rice hull, carbonized rice hull, decomposed sawdust, perlite and granular rock wool were mixed and used. The concentration of nutrient solution were adjusted to EC $0.5{\sim}1.5mS/cm$. The volumetric moisture contents became higher as peat moss mixed were much more. Total porosities in all substrate mixtures were over 80%, and pH in substrate mixtures became lower as the volume of peat moss mixed higher. Mixing ratios of substrates suitable for the production of tomato seedlings with the higher quality were peat moss:rice hull:carbonized rice hull:decomposed sawdust:perlite=25:10:25:20:20(v/v). The plant growth was not significant among the different substrate mixtures. However, plant growth such as plant height, leaf area, and total dry weight became significantly increased as EC increasing.

• Journal of Microbiology and Biotechnology
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• v.29 no.12
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• pp.1982-1992
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• 2019

The alkaliphilic, calcium carbonate precipitating Bacillus sp. strain AK13 can be utilized in concrete for self-repairing. A statistical experimental design was used to develop an economical medium for its mass cultivation and sporulation. Two types of screening experiment were first conducted to identify substrates that promote the growth of the AK13 strain: the first followed a one-factor-at-a-time factorial design and the second a two-level full factorial design. Based on these screening experiments, barley malt powder and mixed grain powder were identified as the substrates that most effectively promoted the growth of the AK13 strain from a range of 21 agricultural products and by-products. A quadratic statistical model was then constructed using a central composite design and the concentration of the two substrates was optimized. The estimated growth and sporulation of Bacillus sp. strain AK13 in the proposed medium were 3.08 ± 0.38 × 10⁸ and 1.25 ± 0.12 × 10⁸ CFU/ml, respectively, which meant that the proposed low-cost medium was approximately 45 times more effective than the commercial medium in terms of the number of cultivatable bacteria per unit price. The spores were then powdered via a spray-drying process to produce a spore powder with a spore count of 2.0 ± 0.7 × 10⁹ CFU/g. The AK13 spore powder was mixed with cement paste, yeast extract, calcium lactate, and water. The yeast extract and calcium lactate generated the highest CFU/ml for AK13 at a 0.4:0.4 ratio compared to 0.4:0.25 (the original ratio of the B4 medium) and 0.4:0.8. Twenty-eight days after the spores were mixed into the mortar, the number of vegetative cells and spores of the AK13 strain had reached 10⁶ CFU/g within the mortar. Cracks in the mortar under 0.29 mm were healed in 14 days. Calcium carbonate precipitation was observed on the crack surface. The mortar containing the spore powder was thus concluded to be effective in terms of healing micro-cracks.

• Journal of Mushroom
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• v.21 no.3
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• pp.185-189
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• 2023

This study was conducted to develop a renewable and sustainable bio-material to replace polystyrene (EPS) in fungal-mycelium-based composite using agricultural by-products. Four mushrooms (Ganoderma lucidum, Fomitella fraxinea, Phellinus linteus, and Schizophyllum commune) were cultured in an oak sawdust plus rice bran substrate to select the mushroom with the best growth. The mycelia of G. lucidum showed the best growth. To investigate the optimal mixing ratio with spent mushroom substrate (SM) and oak sawdust (OS), samples were prepared by mixing SM and OS at ratios of 50%:50%, 60%:40%, and 80%:20% (w/w). Each substrate was then inoculated with G. lucidum. G. lucidum showed the best mycelial growth of 140.0 mm in the substrate with SM and OS mixed at a 60%:40% ratio. It was also found that the substrate with SM and OS mixed at a 60%:40% ratio had the best handling properties. The compressive strength of mycelial materials inoculated with G. lucidum was in the range of 300-302 kgf mm^-1, and the materials were four times stronger than polystyrene materials. These results indicate that substrates comprising spent mushroom substrate mixed with oak sawdust can be successfully upcycled to mycelium-based composite materials using G. lucidum. This represents a sustainable approach.

• Progress in Superconductivity
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• v.11 no.1
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• pp.47-51
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• 2009

For many large-scale applications of high-temperature superconducting materials, large critical current density ($J_c$) in high applied magnetic fields are required. A number of methods have been reported to introduce artificial pinning centers in $YBa_2Cu_3O_{7-{\delta}}$ films for enhancement of their $J_c$. We studied the microstructures and characteristic of $YBa_2Cu_3O_{7-{\delta}}$ films fabricated on $SrTiO_3$ (100) substrates with ZnO nanorods as pinning centers. Au catalyst nanoparticles were synthesized on STO substrates with self assembled monolayer to control the number of ZnO nanorods. The density of Au nanoparticles is approximately $240{\sim}260{\mu}m^{-2}$ with diameters of $41{\sim}49nm$. ZnO nanorods were grown on STO by hot-walled PLD with Au nanoparticles. Typical size of ZnO nanorod was around 179 nm in diameter and $2{\sim}6{\mu}m$ in length respectively. YBCO films deposited directly on STO substrates show the c-axis orientation, while YBCO films with ZnO nanorods exhibit any mixed phases without any typical crystal orientation.

• Microbiology and Biotechnology Letters
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• v.20 no.1
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• pp.91-95
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• 1992

The hydrolyzates of lignocellulosic biomass contain a mixture of glucose, xylose and cellobiose. The yeast which can produce ethanol efficiently from xylose and cellobiose was selected and its growth and ethanol formation behavior on each sugar and their mixture were investigated. Ethanol yields during batch culture of Pichia stipitis CBS 5776 were 0.4. 0.36 and 0.23 g/g substrate on glucose, xylose and cellobiose, respectively. Mixed sugar fermentation data indicate that glucose causes catabolite regulation on xylose and cellobiose utilization. However, xylose and cellobiose were utilized simultaneously. Ethanol yields on mixtures of sugars were generally additive for each of the substrates.

• Bulletin of the Korean Chemical Society
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• v.25 no.11
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• pp.1681-1686
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• 2004

Self-assembled systems with polyamidoamine (PAMAM) dendrimers combined with gold nanoparticles have been widely studied because of their potential applications in molecular electronics, catalyst carriers, chemical sensors, and biomedical devices. In our work, gold nanoparticle monolayers and multilayers with pure and ferrocene-tethered PAMAM dendrimers as cross-linking molecules were deposited on a mixed self-assembled monolayer of gold substrates. The various generations of PAMAM dendrimers can be covalently attached to mercaptoundecanoic acid mixed with a mercaptoundecanol self-assembled monolayer. Cyclic voltammograms show that redox peak currents on the alternate multilayers of gold nanoparticles and ferrocene-tethered PAMAM dendrimers increase as the number of layers increases. Fourier transform IR external reflection spectroscopy and scanning electron microscopy support the results from electrochemical measurements.

• Bulletin of the Korean Chemical Society
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• v.19 no.7
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• pp.743-746
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• 1998

The Belousov-Zhabotinskii (BZ) reaction, which is composed of a bromate-organic acid-metal catalyst and an acidic solution is a commonly employed chemical oscillating reaction system. Cyclohexanedione (CHD) has been used as an initial organic substrate in oscillation systems. We studied each system of 1,4-CHD/BrO3-/Ce4/H+ and 1,3-CHD/BrO3-/Ce4+/H+ oscillating reactions, and studied the control of oscillating characters in a CHD/BrO3-/Ce4+/H+ batch system using a mixed substrate of 1,4-CHD and 1,3-CHD under a fixed total CHD concentration. In the mixed reactions, 1,4-CHD was used as a main substrate and small amounts of 1,3-CHD were used in order to vary the oscillatory behaviours by changing the mixing amount ratio of two substrates.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2431-2437
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• 2014

In this study, Ni, Ni-Cu and Ni/Cu catalysts were deposited onto C-fiber textiles via the electrophoretic deposition method, and the growth characteristics of carbon nanofibers on the deposited catalyst/C-fiber textiles were investigated. The catalyst deposition onto C-fiber textiles was accomplished by immersing the C-fiber textiles into Ni or Ni-Cu mixed solutions, producing the substrate by post-deposition of Ni onto C-fiber textiles with pre-deposited Cu, and passing it through a gas mixture of $N_2$, $H_2$ and $C_2H_4$ at $700^{\circ}C$ to synthesize carbon nanofibers. For analysis of the characteristics of the synthesized carbon nanofibers and the deposition pattern of catalysts, SEM, EDS, BET, XRD, Raman and XPS analysis were conducted. It was found that the amount of catalyst deposited and the ratio of Ni deposition in the Ni-Cu mixed solution increased with an increasing voltage for electrophoretic deposition. In the case of post-deposition of Ni catalyst onto substrates with pre-deposited Cu, both bimetallic catalyst and carbon nanofibers with a high level of crystallizability were produced. Carbon nanofibers yielded with the catalyst prepared in Ni and Ni-Cu mixed solutions showed a Y-shaped morphology.

• Journal of the Korean Ceramic Society
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• v.43 no.5 s.288
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• pp.265-269
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• 2006

We have deposited NiO films by RF sputtering on $Al_2O_3/SiO_2/Si$ and 100 nm-thick Gd doped $CeO_2$ covered $Al_2O_3/SiO_2/Si$ substrates at various $Ar/O_2$ ratios. The deposited films were reduced to form porous Ni thin fllms in 4% $H_2\;at\;400^{\circ}C$. For the films deposited in pure Ar, the reduction was retarded due to the thickness and the orientation of the NiO films. On the other hand, the films deposited in oxygen mixed ambient were reduced and formed porous Ni films after 20 min of reduction. We also investigated the possibility of using the films for the single chamber operation by studying the electrical property of the films in the fuel/air mixed environment. It is shown that the resistance of the Ni film increases quickly in the mixed gas environment and thus further improvements of Ni-base anodes are required for using them in the single chamber operation.