• Resources Recycling
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• v.18 no.6
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• pp.18-23
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• 2009

An investigation on the synthesis of aluminum citrate, one of the aluminum organic compounds, has been performed using aluminum chloride solutions as a starting material. For the synthesis of aluminum citrate, citric acid was added to aluminum solutions with the mole ratio of citric acid to aluminum to be 2.5 and aluminum citrate synthesized was also characterized in terms of chemical analysis, X-ray diffraction, particle size measurement and SEM analysis. As a result, it was found that the ratio of ethanol/Al solution more than 4.0 was required for the synthesis of aluminum citrate from aluminum solutions. Furthermore, the pH should be controlled to be more than 7.0 in order to obtain the recovery of aluminum citrate higher than 97%. From the chemical analysis of aluminum citrate synthesized in this work, the content of $NH_4$, Al and C was found to be 17.0, 4.01 and 25.7%, respectively. Accordingly, the aluminum citrate synthesized from aluminum solutions was confirmed to be $(NH_4)_5Al(C_6H_4O_7)_2{\cdot}2H_2O$.

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.11a
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• pp.112-112
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• 1999

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.565-568
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• 2013

Acetyl-CoA carboxylases (ACCs) play critical roles in fatty acid synthesis and oxidation by the catalytic activity of the carboxylation of acetyl-CoA to malonyl-CoA. It is known that ACCs are inactivated through reversible phosphorylation by AMP-activated protein kinase (AMPK) and allosterically activated by citrate. Here, we determined the crystal structures of biotin carboxylase (BC) domain of human ACC2 phosphorylated by AMPK in the presence of citrate in order to elucidate the activation mechanism by citrate. This structure shows that phosphorylated Ser222 is released from the dimer interface, and thereby facilitating the dimerization or oligomerization of the BC domain allosterically. This structural explanation is coincident with the experimental result that the phosphorylated Ser222 was dephosphorylated more easily by protein phosphatase 2A (PP2A) as the citrate concentration increases.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.554-554
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• 2012

Controlling the size distribution of gold nanoparticles (NPs) is of great importance due to the fact that their properties are strongly dependent upon the size distribution as well as the size itself. In the citrate reduction method for gold NP synthesis, the citrate works as (1) a reducing agent, (2) a surfactant, and also (3) a weak base: it raises the pH of the whole reaction mixture. Here, we have extensively studied the all three roles of the citrate, by adding other reagents separately (NaBH4, CTAB, and NaOH) for the independent control of the three roles of the citrate. Among the roles of the citrate, that as a weak base was found to be the most critical parameter affecting the size distribution of gold NPs and the size distribution became much more improved with the increase of the solution pH, while adding a supplementary surfactant or reducing agent resulted in the formation of less homogeneous NPs.

• Microbiology and Biotechnology Letters
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• v.20 no.2
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• pp.207-212
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• 1992

An anti-inflammatory agent, serratiopeptidase, was produced from the culture of the Serratia marcescens. The effects of carbon sources, nitrogen sources and inducers on the production were investigated. Citrate was found to be inhibitory in the production of serratiopeptidase. The enzyme was synthesized in the synthetic medium without inducers, albeit low level of synthesis. But the synthesis was increased by the addition of proteinaceous substrate and leucine. Induction of extracellular proteinase by its end-product was discovered, which is not common in the proteinase synthesis in the bacteria. By the glucose fed-batch culture, we found the possible catabolite repression on the production of serratiopeptidase.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.165.2-165
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• 2003

• The Microorganisms and Industry
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• v.12 no.2
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• pp.30-35
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• 1986

Almost all of the aerobic organisms contain citric acid cycle (or, tricarboxylic acid cycle). This cycle is involved both in energy metabolism and biosynthetic reactions; generation of NADH which derives the synthesis of chemical energy, ATP, and provision of intermediates needed for the biosynthesis. Because of its importance in the cellular metabolism, the regulation of the TCA cycle and its component enzymes has been extensively studied by many biologists (7,28). Citrate synthase is resposible for the initial step of the cycle and has been recognized as the rate limiting step (14,121,26). Understanding of the mechanism of the expression of citrate synthase should be a key step for the elucidation of the regulation of the TCA cycle in the cell metabolism.

• The Korean Journal of Ceramics
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• v.5 no.3
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• pp.217-223
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• 1999

Proten-conductive $SrZr_{0.95} Y_{0.05} O_{2.975}$ powder was prepared by citrate gel method its characteristics and sinterability were investigated. Amorphous gel could be obtained from a citric acid solution that $SrCO_3$ and metal nitrates were dissolved. The initial decomposition of the gel proceeded up to $250^{\circ}C$, followed by combustion of its decomposition products in the temperature range from $250^{\circ}C$ to $500^{\circ}C$. A well-crystallized perovskite phase with a stoichiometric composition after calcination at $1000^{\circ}C$. Sintering green compacts of this powder for 6 h showed a considerable densification to start at $1200^{\circ}C$ and resulted in 86.8% and 96.5% relative densities at $1400^{\circ}C$ and $1600^{\circ}C$, respectively. Whereas, the powder compacts prepared by solid state reaction had much lower relative densities, 73% at $1400^{\circ}C$ and 92% at $1600^{\circ}C$.

• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.76-80
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• 2010

In this study, YDC powders with uniform composition and particle size were synthesized by a citrate method and their thin film deposition was conducted by electrospray deposition method. Polymeric precursor was prepared first by reaction of metal salts with citrate acid and ethylene glycol. Fluorite crystalline YDC powders were obtained by calcining the precursor at $750^{\circ}C$ for 3 h. The electrospray deposited films prepared at the optimum conditions became dense and defect-free after heat treatment at $1400^{\circ}C$ for 3 h. The film thickness was linearly varied with the deposition time.

• Journal of the Korean Ceramic Society
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• v.33 no.9
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• pp.1003-1011
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• 1996

Hydroxyapatite powder was synthesized by a citrate method, . Char-like precursor composed of Ca8(HPO4)2(PO4)4.5H2O (OCP) and CaCo3 was found via viscous resin-like intermediate by heating the mixed aqueous solution of Ca(NO3)2.4H2O(NH4)2HPO4 and citric acid. Resulted powder was transformed into hydroxyapatite phase by firing over 120$0^{\circ}C$-135$0^{\circ}C$ for 4 hr using the powder calcined at 90$0^{\circ}C$ for 10 hr composed of mostly single hydroxyapatite phase. The sintered densities increased with firing temperature up to 130$0^{\circ}C$ but the highest relative density was about 94% of theoritical value. indicating the presence of closed pores. The maximum 96 MPa of flexural strength was obtained at 120$0^{\circ}C$ firing but the flexural strength showed lower values over the above sintering condition. Vitro test was performed by immersing of two jointed specimens in SBF for seven days and adhesion was observed between two specimens.