• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.196-208
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• 2018

The effect of channel-system of zeolite on methanol-to-DME reaction was studied. Results revealed that channels size and topology affect catalyst lifetime, type and location of coke precursors. FER and MFI showed the best resistance towards coke deposition, whilst fast deactivation was observed on MOR. Although the higher concentration and strength of acid sites, FER structure formed a lower coke amount, preferably located within the pores, while coke cluster deposited on the external surface of MOR. Analysis of acid sites distribution and strength was performed during deactivation-regeneration process. Coke location assessment was also supported by molecular simulations.

• Bulletin of the Korean Chemical Society
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• v.14 no.6
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• pp.726-732
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• 1993

A comparative study on cadmium(II) complexation with three well characterized humic acids (SHA: soil humic acid from the Okchun Metamorphic Belt; AqHA: aquatic humic acid from Gorleben underground aquifer, Germany; CoHA: commercially available humic acid from the Aldrich Co.) was carried out in 0.1 M $NaClO_4$ at different solution pH(5.0, 5.5, and 6.0) using the ultrafiltration technique. The maximum binding ability (MBA) of the humic acids for cadmium(II) was observed to vary with their origins and solution pH. The results suggest that 1 : 1 complex predominates within the experimental range, and the conditional stability constants were calculated based on the assumption of cooperative binding, yielding log K values that were quite similar (CoHA: 4.17${\pm}$0.08; AqHA: 4.14${\pm}$0.07; SHA: $4.06{\pm} 0.12\;l\;mol^{-1}$ at pH 6.0) irrespective of humic acid origins or pH. By contrast a nonlinear Schatchard plot was obtained, using the cadmium(II) ion selective electrode speciation analysis method, which indicated that humic acid may have two or more classes of binding sites, with $log\;K_1\;and\;log\;K_2$ of 4.73${\pm}$ 0.08 and $3.31{\pm}0.14\;l\;mol^{-1}$ respectively.

• Nano
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• v.13 no.11
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• pp.1850132.1-1850132.14
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• 2018

The direct synthesis of metal-organic frameworks (MOFs) with acidic and basic active sites is challenging due to the introduction of functional groups by post-functionalization method often jeopardize the framework integrity. Herein, we report the direct synthesis of acid-base bifunctional MOFs with tuning acid-base strength. Employing modulated hydrothermal (MHT) approach, microporous MOFs named $UiO-66-NH_2$ was prepared. Through the ring-opening reaction of 1,3-propanesultone with amino group, $UiO-66-NH_2-SO_3H-type$ catalysts can be obtained. The synthesized catalysts were well characterized and their catalytic performances were evaluated in one-pot glucose to 5-HMF conversion. Results revealed the acid-base bi-functional catalyst possessed high activity and excellent stability. This work provides a general and economically viable approach for the large-scale synthesis of acid-base bi-functional MOFs for their potential use in catalysis field.

• The KIPS Transactions:PartD
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• v.19D no.1
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• pp.21-28
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• 2012

Predication of protein interaction sites for monomer structures can reduce the search space for protein docking and has been regarded as very significant for predicting unknown functions of proteins from their interacting proteins whose functions are known. In the other hand, the prediction of interaction sites has been limited in crystallizing weakly interacting complexes which are transient and do not form the complexes stable enough for obtaining experimental structures by crystallization or even NMR for the most important protein-protein interactions. This work reports the calculation of 3D surface patches of complex structures and their properties and a machine learning approach to build a predictive model for the 3D surface patches in interaction and non-interaction sites using support vector machine. To overcome classification problems for class imbalanced data, we employed an under-sampling technique. 9 properties of the patches were calculated from amino acid compositions and secondary structure elements. With 10 fold cross validation, the predictive model built from SVM achieved an accuracy of 92.7% for classification of 3D patches in interaction and non-interaction sites from 147 complexes.

• Journal of Microbiology and Biotechnology
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• v.19 no.10
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• pp.1098-1102
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• 2009

Gamma-linolenic acid (GLA, C18:3 ${\Delta}^{6,9,12}$) is synthesized by a delta-6 fatty acid desaturase using linoleic acid (LA, C18:2 ${\Delta}^{9,12}$) as a substrate. To enable the production of GLA in the conventional yeast Pichia pastoris, we have isolated a cDNA encoding the delta-6 fatty acid desaturase from Cunninghamella echinulata MIAN6 and confirmed its function by heterogeneous expression in P. pastoris. Sequence analysis indicated that this cDNA sequence has an open reading frame of 1,404 bp, which encodes a 52 kDa peptide of 468 amino acids. This sequence has 64% identity to the previously reported delta-6 fatty acid desaturase from Rhizopus oryzae. The polypeptide has a cytochrome b5 domain at the N-terminus including the HPGG motif in the heme-binding region, as reported for other delta-6 fatty acid desaturases. In addition, this enzyme differs from other desaturases by the presence of three possible N-linked glycosylation sites. Analysis of the fatty acid composition demonstrated the accumulation of GLA to the level of 3.1% of the total fatty acids. Notably, the amounts of ginkgolic acid (C17:1) and palmitic acid (C16:0) were increased from 1.3% to 29.6% and from 15% to 33%, respectively. These results reveal that the modification of the fatty acid biosynthetic pathway by genetic manipulation in order to produce specific polyunsaturated fatty acids in P. pastoris is a promising technique.

• BMB Reports
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• v.39 no.6
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• pp.686-695
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• 2006

Interleukin-2 enhancer binding factor 2 (ILF2) was reported to regulate transcription of interleukin-2 (IL-2), a central cytokine in the regulation of T-cell responses. This property of ILF2 was well characterized in human and mammals, but little is known in bony fish. In this paper, an ILF2 homologue was cloned and well characterized from Tetraodon nigrovirid is for the further investigation of the function of ILF2 in bony fish. The full-length Tetraodon ILF2 cDNA was 1380 bp in size and contained an open reading frame (ORF) of 1164 bp that translates into a 387 amino-acid peptide with a molecular weight of 42.9 kDa, a 5' untranslated region (UTR) of 57 bp, and a 3' UTR of 159 bp containing a poly A tail. The deduced peptide of Tetraodon ILF2 shared an overall identity of 58%~93% with other known ILF2 sequences, and contained two N-glycosylation sites, two N-myristoylation sites, one RGD cell attachment sequence, six protein kinase C phosphorylation sites, one amino-terminal RGG-rich single-stranded RNA-binding domain, and a DZF zinc-finger nucleic acid binding domain, most of which were highly conserved through species compared. Constitutive expression of Tetraodon ILF2 was observed in all tissues examined, including gill, gut, head kidney, spleen, liver, brain and heart. The highest expression was detected in heart, followed by liver, head kidney and brain. Stimulation with LPS did not significantly alter the expression of Tetraodon ILF2. Gene organization analysis showed that the Tetraodon ILF2 gene have fifteen exons, one more than other known ILF2 genes in human and mouse. Genes up- and down-stream from the Tetraodon ILF2 were Rpa12, Peroxin-11b, Smad4, Snapap and Txnip homologue, which were different from that in human and mouse.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.2
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• pp.81-86
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• 2015

Soil management for orchard depends on the effects of soil microbial activities. The present study evaluated the soil microbial community of 25 orchard (5 sites for sandy loam, 7 sites for silt loam, and 13 sites for loam) in Gyeongnam Province by fatty acid methyl ester (FAME) method. The average values for 25 orchard soil samples were $270nmol\;g^{-1}$ of total FAMEs, $72nmol\;g^{-1}$ of total bacteria, $34nmol\;g^{-1}$ of Gram-negative bacteria, $34nmol\;g^{-1}$ of Gram-positive bacteria, $6nmol\;g^{-1}$ of actinomycetes, $49nmol\;g^{-1}$ of fungi, and $7nmol\;g^{-1}$ of arbuscular mycorrhizal fungi. In addition, silt loam soils had significantly low ratio of cy17:0 to $16:1{\omega}7c$ and cy19:0 to $18:1{\omega}7c$ compared with those of loam soils (p < 0.05), indicating that microbial activity increased. The average soil microbial communities in the orchard soils were 26.7% of bacteria, 17.9% of fungi, 12.6% of Gram-negative bacteria, 12.5% of Gram-positive bacteria, 2.5% of arbuscular mycorrhizal fungi, and 2.2% of actinomycetes. The soil microbial community of Gram-negative bacteria in silt loam soils was significantly higher than those of sandy loam and loam soils (p < 0.05).

• Molecules and Cells
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• v.37 no.4
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• pp.345-355
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• 2014

Mitigating secondary delayed neuronal injury has been a therapeutic strategy for minimizing neurological symptoms after several types of brain injury. Interestingly, secondary neuronal loss appeared to be closely related to functional loss and/or death of astrocytes. In the brain damage induced by agonists of two glutamate receptors, N-ethyl-D-aspartic acid (NMDA) and kainic acid (KA), NMDA induced neuronal death within 3 h, but did not increase further thereafter. However, in the KA-injected brain, neuronal death was not obviously detectable even at injection sites at 3 h, but extensively increased to encompass the entire hemisphere at 7 days. Brain inflammation, a possible cause of secondary neuronal damage, showed little differences between the two models. Importantly, however, astrocyte behavior was completely different. In the NMDA-injected cortex, the loss of glial fibrillary acidic protein-expressing ($GFAP^+$) astrocytes was confined to the injection site until 7 days after the injection, and astrocytes around the damage sites showed extensive gliosis and appeared to isolate the damage sites. In contrast, in the KA-injected brain, $GFAP^+$ astrocytes, like neurons, slowly, but progressively, disappeared across the entire hemisphere. Other markers of astrocytes, including $S100{\beta}$, glutamate transporter EAAT2, the potassium channel Kir4.1 and glutamine synthase, showed patterns similar to that of GFAP in both NMDA- and KA-injected cortexes. More importantly, astrocyte disappearance and/or functional loss preceded neuronal death in the KA-injected brain. Taken together, these results suggest that loss of astrocyte support to neurons may be a critical cause of delayed neuronal death in the injured brain.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.100-101
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• 2004

Many researches in Korea have been performed to understand the pollution of stream waters by acid mine drainage. However, few studies have been conducted regarding the effect of particulate and colloidal fractions on the transport of trace metals. To estimate harmful effects of trace metals, it is important to evaluate the particulate and colloidal metals as well as dissolved metals, because particulate and colloidal fractions of trace metals play an important role in transport of trace metals and may adversely affect habitats and organisms in riverine system. Colloids are solids with effective diameters in size range from 0.001 $\mu$m to 1 $\mu$m. According to Jone et al. (1974), metals in surface water, like Al, Fe, and Mn, require filtration with pore-size membranes smaller than 0.45 $\mu$m to define dissolved concentrations. The main objective of this study is to understand the effects of particulate, colloidal, and truly dissolved fractions on the transport and fate of trace metals in acid mine drainage. This study was conducted for the Onjeong creek in the Uljin mine area. Sampling was carried out in 13 sites, spatially covering the area from mine dumps to the downstream Onjeong reservoir. To examine the metal partitioning between particulate, colloidal, and truly dissolved fraction, we used successive filtration techniques consisting of conventional method (using 0.45 $\mu$m membranes) and tangential-flow ultrafiltration (using 0.001 $\mu$mm membranes). Ultrafiltration may seperate much smaller particles from aqueous phase (Josephson, 1984; Hernandez and Stallard, 1988). The analysis of metals were performed by inductively coupled plasma - atomic emission spectrometer (ICP-AES: model Perkin Elmer OPTIMA3000XL). Anions such as SO$_4$, Cl and NO$_3$ were measured with ion chromatograph (IC: model Dionex 120). Sample analysis is still in progress. The preliminary data show that the studied creek is severely polluted by Al, Fe, Mn, Pb and Zn. Toward upstream sites with relatively lower pH, less than 50% of Al and Fe occur in the sorbed form on particles or colloids, whereas more than 80% of Al and Fe occur in the sorbed form in downstream sites or tributaries with relatively higher pH. Less than 30% of Zn is present in particle or colloidal forms in the whole range of creek. Truly dissolved fraction of trace metals is negatively correlated with pH. The Kd values for Al, Fe and Zn consistently increase with increasing pH and decrease with increasing particle concentration.

• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.121-126
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• 2015

The objective of this study is to evaluate the catalytic potential of the porous material prepared from water treatment sludge. The textural properties of the catalyst were studied using $N_2$ adsorption and desorption isotherms, scanning electron microscope, and X-ray diffraction. The pellet-type catalyst prepared using water treatment sludge is determined to be a material that contains mesopores as well as micropores. The specific surface area of the catalyst is $157m^2/g$. Acidic characteristics of the catalyst are analyzed by temperature-programmed desorption of ammonia and infrared spectroscopy of adsorbed pyridine. 2-Butanol dehydration reaction was carried out in a fixed bed catalytic reactor. Yields of 1-butene, trans-2-butene, and cis-2-butene at $350^{\circ}C$ were 25.6 wt%, 19.2 wt%, and 29.9 wt%, respectively. This catalytic activity of the catalyst based on water treatment sludge in 2-butanol dehydration is due to the acid sites composed of Bronsted acid sites and Lewis acid sites. It was confirmed that the catalyst based on water treatment sludge can be utilized to produce $C_4$ olefin through butanol dehydration.