Publications by authors named "Byung-Hyuk Kim"

We developed a novel battery system consisting of a hybrid (LiCoO + LiVO) cathode in a cell with a hybrid (graphite + Li-metal) anode and compared it with currently used systems. The hybrid cathode was synthesized using various ratios of LiCoO:LiVO, where the 80:20 wt% ratio yielded the best electrochemical performance. The graphite and Li-metal hybrid anode, the composition of which was calculated based on the amount of non-lithiated cathode material (LiVO), was used to synthesize a full cell.

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A new coating method called vapor-phase polymerization (VPP) is used to coat a conductive polymer on LiVO (LVO) surfaces for the first time in lithium-metal secondary batteries to protect the interface layer and enhance the electrochemical properties of the cathode. The VPP method can be used to coat an appropriate amount of the polymer and homogeneously coat the LVO active material surfaces because of the use of vapor-phase monomers. The presence of the coating layer was confirmed by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy.

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Algae undergo a complete metabolic transformation under stress by arresting cell growth, inducing autophagy and hyper-accumulating biofuel precursors such as triacylglycerols and starch. However, the regulatory mechanisms behind this stress-induced transformation are still unclear. Here, we use biochemical, mutational, and "omics" approaches to demonstrate that PI3K signaling mediates the homeostasis of energy molecules and influences carbon metabolism in algae.

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The high rate algal ponds (HRAP) powered and mixed by a paddlewheel have been widely used for over 50 years to culture microalgae for the production of various products. Since light incidence is limited to the surface, water depth can affect microalgal growth in HRAP. To investigate the effect of water depth on microalgal growth, a mixed microalgal culture constituting three major strains of microalgae including sp.

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Article Synopsis
  • Researchers are exploring how environmental stress, like high salinity, can boost lipid accumulation in algal cells, potentially improving algal oil production for industrial use.
  • The study found that the microalga Chlorella sorokiniana HS1 showed significant lipid accumulation when subjected to high salinity and supplemented with bicarbonate, maintaining cell integrity.
  • A successful two-phase cultivation process was demonstrated, resulting in a 12% increase in lipid content while also indicating a carbon reallocation inside the cells, which enhances the understanding of algal growth under stress conditions.
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It is established that biodiversity determines productivity of natural ecosystems globally. We have proved that abiotic factors influenced biomass productivity in engineered ecosystems i.e.

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Algae and bacteria have coexisted ever since the early stages of evolution. This coevolution has revolutionized life on earth in many aspects. Algae and bacteria together influence ecosystems as varied as deep seas to lichens and represent all conceivable modes of interactions - from mutualism to parasitism.

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The bead type MgO-MgAl2O4 catalyst supports with bimodal pore structures were fabricated via an extrusion molding of gels derived from the precursor mixture of mesoporous MgO particles and aluminum magnesium hydroxide, followed by heat treatment. To investigate the effect of macro pore structures on the catalytic activity of the Ni/MgO-MgAl2O4 catalysts in the steam and carbon dioxide reforming of methane (SCR), two kinds of the catalysts with largely different macro pore volumes and sizes but nearly the same meso pore volume and size were compared. The bimodal catalyst with a large macro pore size and volume exhibited a highly enhanced CO2 conversion from 22.

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The potential of microalgae biofuel has not been realized because of the low productivity and high costs associated with the current cultivation systems. In this study, a new low-cost and transparent attachment material was tested for cultivation of a filamentous algal strain, Stigeoclonium sp., isolated from wastewater.

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Algae based wastewater treatment coupled to biofuel production has financial benefits and practical difficulties. This study evaluated the factors influencing diversity and growth of indigenous algal consortium cultivated on untreated municipal wastewater in a high rate algal pond (HRAP) for a period of 1 year using multivariate statistics. Diversity analyses revealed the presence of Chlorophyta, Cyanophyta and Bacillariophyta.

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A polyphasic taxonomic study was carried out on strain EBR-4-1(T), which was isolated from a biofilm reactor in the Republic of Korea. The cells of the strain were Gram-stain-negative, non-spore-forming, motile and rod-shaped. Comparative 16S rRNA gene sequence studies showed a clear affiliation of this strain to the Alphaproteobacteria, and it was most closely related to Chelatococcus daeguensis CCUG 54519(T), Chelatococcus sambhunathii HT4(T), and Chelatococcus asaccharovorans DSM 6462(T) with 16S rRNA gene sequence similarities to the type strains of these species of 98.

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This study demonstrates that ecologically engineered bacterial consortium could enhance microalgal biomass and lipid productivities through carbon exchange. Phycosphere bacterial diversity analysis in xenic Chlorella vulgaris (XCV) confirmed the presence of growth enhancing and inhibiting microorganisms. Co-cultivation of axenic C.

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Open raceway ponds are cost-efficient for mass cultivation of microalgae compared with photobioreactors. Although low-cost options like wastewater as nutrient source is studied to overcome the commercialization threshold for biodiesel production from microalgae, a cost analysis on the use of wastewater and other incremental increases in productivity has not been elucidated. We determined the effect of using wastewater and wavelength filters on microalgal productivity.

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A Gram-stain-positive, aerobic, non-motile, non-spore-forming, cocci-shaped actinobacterium, designated strain EBR4-1-2(T), was isolated from a biofilm reactor in Korea. Comparative 16S rRNA gene sequence studies showed the isolate was clearly affiliated with the class Actinobacteria, and was related most closely to Flaviflexus huanghaiensis H5(T), showing 98.9 % similarity.

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This study evaluated the growth and nutrient removal ability of an indigenous algal consortium on real untreated municipal wastewater in a high rate algal pond (HRAP). The HRAP was operated semicontinuously under different hydraulic retention times (HRT: 2, 4, 6, and 8 days). The average removal efficiencies of chemical oxygen demand, and total nitrogen and phosphate of real municipal wastewater were maintained at 85.

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A novel bacterial strain designated GJW-30(T) was isolated from soil of the lava forest, Gotjawal, located in Aewol, Jeju, Korea. Strain GJW-30(T) was found to be strictly aerobic, Gram-negative and to form pleomorphic, non-motile rods and white colonies on R2A agar. The major fatty acids were identified as C18:1ω7c, C16:0 and C17:0, the predominant isoprenoid quinone as Q-10, the polar lipids as diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, an unidentified aminolipid and an unidentified lipid.

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We demonstrated a comprehensive approach for development of axenic cultures of microalgae from environmental samples. A combination of ultrasonication, fluorescence-activated cell sorting (FACS), and micropicking was used to isolate axenic cultures of Chlorella vulgaris Beyerinck (Beijerinck) and Chlorella sorokiniana Shihira & R.W.

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A cultivation system in the two-stage photoautotrophic-photoheterotrophic/mixotrophic mode was adapted to maximize lipid productivity of two freshwater strains of Chlorella sp. grown in brewery wastewater (BWW). The endogenous Chlorella sp.

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Flocculation is most preferred method for harvesting microalgae, however, the role of bacteria in microalgal flocculation process is still unknown. This study proves that bacteria play a profound role in flocculating by increasing the floc size resulting in sedimentation of microalgae. A flocculating activity of 94% was achieved with xenic Chlorella vulgaris culture as compared to 2% achieved with axenic culture.

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Phenotypic and genotypic changes in Chlamydomonas reinhardtii BafJ5, a starchless mutant, with respect to lipid metabolism was studied in different trophic states under nitrogen (N) sufficient and limited conditions. Interestingly, cellular lipid content increased linearly with input acetate concentration with highest lipid content (∼42%) under nitrogen limitation and mixotrophic state. RT-qPCR studies indicate that key fatty acid biosynthesis genes are down-regulated under N limitation but not under mixotrophic state, whereas, ACS2, encoding Acetyl-CoA synthetase, and DGTT4, encoding Diacylglycerol O-acyltransferase, are up-regulated under all conditions.

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This study deals with an effective nucleic acids extraction method from various strains of Botryococcus braunii which possesses an extensive extracellular matrix. A method combining freeze/thaw and bead-beating with heterogeneous diameter of silica/zirconia beads was optimized to isolate DNA and RNA from microalgae, especially from B. braunii.

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The aim of this study was to apply loess balls containing effective microorganisms (EM) to the remediation of contaminated harbor sediments, and to thereby elucidate the functions of EM in remediation. Changes in physicochemical, biochemical, and microbiological parameters were measured to monitor the remediation process at a laboratory scale. Treatment with high concentrations of EM stock culture and EM loess balls (4%), and a low concentration of EM loess balls (0.

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A mixed, anaerobic microbial enrichment culture, AMEC-4P, was developed that uses lactate as the electron donor for the reductive dechlorination of tetrachloroethene (PCE) to ethene. AMEC-4P consistently and completely converted 2 mM PCE to cis-1,2-dichloroethene (cis-DCE) within 13 days, and the intermediate, cis-DCE, was then completely dechlorinated to ethene after 130 days. Dechlorination rates for PCE to cis-DCE, cis-DCE to VC, and VC to ethene were 243, 27, and 41 μmol/l/day, respectively.

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Uniformly and vertically well-aligned ZnO nanorods were fabricated in-situ and ex-situ on ZnO films using a catalyst-free metal-organic chemical vapor process. Microstructural properties of the initial growth of ZnO nanorods on ZnO films with different surface roughnesses were investigated. We observed that the ZnO nanorods grown on ZnO films with surface roughness of less than 1.

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We evaluated the activity and abundance of the crude oil- degrading bacterium Nocardia sp. H17-1 during bioremediation of oil-contaminated soil, using real-time PCR. The total petroleum hydrocarbon (TPH) degradation rate constants (k) of the soils treated with and without H17-1 were 0.

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