Kichul Cho

Effects of grain shape and texture on the yield strength anisotropy of Al-Li alloy sheet

The in-plane anisotropy of yield strength in aluminum-lithium (Al-Li) alloys has been attributed to crystallographic textures, grain morphologies, and directional precipitates. Hot-rolled Al-Li alloys are reported to exhibit the minimum yield strength near 45{degree} to the rolling direction due to rolling textures (i.e., Cu, S and Bs components in {beta}-fiber) and elongated grains. During recrystallization treatment in the thermo-mechanical processing, continuous recrystallization (CRX) or discontinuous recrystallization (DRX) can take place. It is known that CRX occurs by formation and growth of subgrains, while the DRX occurs by growth of newly developed nuclei with different crystal orientations from those of original grains. CRX hardly alters texture, on the contrary DRX completely changes the texture. The grain morphology of CRX, affected by rolling and recrystallization conditions, can be controlled without changing crystallographic textures. In this work, equiaxed grains with rolling textures are obtained by CRX, and the contributions of grain shape and texture to the in-plane anisotropy of yield strength have been identified in an Al-Li-Cu-Mg-Zr-Mn alloy.

Anti-metastatic effects of the sulfated polysaccharide ascophyllan isolated from Ascophyllum nodosum on B16 melanoma.

We previously found that ascophyllan, a sulfated polysaccharide isolated from brown seaweed Ascophyllum nodosum, exhibited antitumor activity in sarcoma-180 tumor-bearing mice. In this study, we found that ascophyllan inhibited the migration and adhesion of B16 melanoma cells by reducing the expression of N-cadherin and enhancing the expression of E-cadherin in a concentration-dependent manner. Transwell invasion assay revealed that ascophyllan suppressed the invasion ability of B16 cells. It also inhibited the expression of matrix metalloprotease-9 (MMP-9) mRNA and the secretion of MMP-9 protein in B16 cells, a process that may involve the extracellular signal-regulated kinase (ERK) signaling pathway. Furthermore, ascophyllan administered intraperitoneally at 25 mg/kg showed anti-metastatic activity in a mouse model of metastasis induced by intravenous injection of B16 cells, and the number of lung surface metastatic nodules in ascophyllan-treated mice was significantly reduced compared to that in the untreated control mice. Since splenic natural killer cell activity enhanced in the mice injected with ascophyllan intraperitoneally, we suggest that ascophyllan may exhibit in vivo anti-metastatic activity on B16 melanoma cells through activation of the host immune system in addition to a direct action on cancer cells.

2,4,6-Trihydroxybenzaldehyde, a potential anti-obesity treatment, suppressed adipocyte differentiation in 3T3-L1 cells and fat accumulation induced by high-fat diet in C57BL/6 mice.

In the present study, 2,4,6-trihydroxybenzaldehyde (THB) was evaluated for inhibitory effects on adipocyte differentiation in 3T3-L1 cells and anti-obesity effects in mice with high-fat diet (HFD)-induced obesity. Lipid accumulation measurement indicated that THB markedly inhibited adipogenesis, and this involved down-regulation of the expression of the adipogenesis-related proteins, CCAAT/enhancer-binding protein α (C/EBPα), peroxisome proliferator-activated receptor γ (PPARγ), fatty acid synthase (FAS) and sterol regulatory element-binding protein-1c (SREBP-1c), in 3T3-L1 pre-adipocyte cells. In a mouse model of HFD-induced obesity, oral administration of THB (5 and 25mg/kg for 13 weeks) reduced the HFD-induced increase in weight gain. THB administration also reduced serum levels of glucose, triglycerides, and total cholesterol. A reduction in the hypertrophy of white adipose tissue was also observed. Furthermore, THB administration inhibited HFD-induced hepatic steatosis. These results provided evidence that administration of THB alleviated HFD-induced obesity in C57BL/6 mice and revealed the potential of THB as a nutraceutical to help prevent or treat obesity and the associated metabolic disorders.

Bioflocculation of the oceanic microalga Dunaliella salina by the bloom-forming dinoflagellate Heterocapsa circularisquama, and its effect on biodiesel properties of the biomass.

The aim of this work was to evaluate the flocculation by the dinoflagellate Heterocapsa circularisquama as a means for harvesting three Chlorophyta species, Chlorella vulgaris, Nannochloropsis granulata, and Dunaliella salina. Relative fluorescence of D. salina culture significantly decreased along with 9.3-fold increased flocculation activity within 24 h when mixed with H. circularisquama. Lipid content of bioflocculated D. salina increased about 40%, while fatty acid methyl ester (FAME) profiles exhibited higher levels of C16:0, C18:0, and C18:1, compared to harvest by centrifugation, suggesting higher energy content. Furthermore, bioflocculated D. salina biomass had more suitable biodiesel properties relative to both EN14214 and ASTMD6751, with a cetane number of 49.0 and an iodine value of 95.9. These results suggest that H. circularisquama-induced bioflocculation is applicable for the sustainable and qualitative production of algal biodiesel.

Characterisation of inorganic elements and volatile organic compounds in the dried sea cucumber Stichopus japonicus

The sea cucumber Stichopus japonicus lives in a variety of marine habitats and is an important cultivated edible aquatic species in East Asia. In this study, S. japonicus, collected from the sea near Jeju Island of Korea, was lyophilised or vacuum-dried and then analysed by gas chromatography-mass spectrometry (GC-MS) or inductively coupled plasma mass spectrometry (ICP-MS). The GC-MS profiles of vacuum-dried and lyophilised samples differed. Based on direct injection and static headspace analysis, 37 volatile organic compounds (VOCs) were identified in vacuum-dried samples and 33 VOCs were identified in lyophilised samples. Therefore, the odour of vacuum-dried sea cucumber is thought to be due to the presence of various VOCs that are absent in lyophilised sea cucumber. According to ICP-MS analysis, the levels of 15 inorganic elements were slightly higher in lyophilised samples than in vacuum-dried samples. The results of the inorganic and organic chemical analyses provide information about the composition of dried sea cucumber.

Anti-inflammatory effect of supercritical extract and its constituents from Ishige okamurae

The anti-inflammatory properties of the supercritical fluid extract of Ishige okamurae (SFEIO) on lipopolysaccharide (LPS)-stimulated murine RAW 264.7 macrophages. The lipid profile of the SFEIO, reviled the presence of palmitic acid (220.2 mg/g), linoleic acid (168.0 mg/g), and oleic acid (123.0 mg/g). SFEIO was found to exert its anti-inflammatory effects through inhibiting nitric oxide (NO), prostaglandin E2 (PGE2), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 production in LPS-stimulated RAW 264.7 cells, without inducing cytotoxicity. SFEIO did not effect on the LPS-induced p38 kinase phosphorylation, whereas it attenuated the extracellular-related signaling kinase (ERK) and c-Jun N-terminal kinase (JNK) phosphorylation. Furthermore, SFEIO inhibited the LPS-induced IκB-α degradation and p50 NF-κB activation. These results suggest that SFEIO exerts its anti-inflammatory effects in LPS-activated RAW 264.7 cells by down-regulating the activation of ERK, JNK, and NF-κB.

Citrimicrobium luteum gen. nov., sp. nov., aerobic anoxygenic phototrophic bacterium isolated from the gut of a sea cucumber Stichopus japonicus

A Gram-stain negative, yellow-pigmented, motile, pleomorphic bacterium, designated strain CBA4602T, was isolated from the gut of the sea cucumber Stichopus japonicus, which was collected from Jeju Island in the Republic of Korea. In a phylogenetic analysis based on the 16S rRNA gene, strain CBA4602T belonged to the order Sphingomonadales in the class Alphaproteobacteria. The 16S rRNA gene sequence similarity between strain CBA4602T and ‘Citromicrobium bathyomarinum’ JF-1, the most closely related strain having nonvalidly published name, was 98.4%, followed by 95.2–96.7% identities with sequence of the other closest strains in the genus Erythrobacter. Strain CBA4602T had bacteriochlorophyll a and carotenoids. Strain CBA4602T grew in 0–10% (w/v) NaCl, at 10–42°C and pH 6.0–8.0, with optimal growth in 1–2% NaCl, at 30–37°C and pH 7.0. Strain CBA4602T was positive for catalase and oxidase activities and was able to hydrolyse gelatine and Tween 20 and 40, but not starch, Tween 80 or l-tyrosine. The G+C content of genomic DNA from strain CBA4602T was 68.0 mol% and Q-10 was the major detected isoprenoid quinone. The polar lipids were three unidentified phospholipids, three unidentified glycolipids, and two unidentified lipids. The dominant fatty acids were anteiso-C15:0, C16:0, anteiso-C17:0 and C18:0. As considering the current taxonomic status of the genus ‘Citromicrobium’ and polyphasic taxonomic analyses, strain CBA4602T represents a novel genus and species. The name Citrimicrobium luteum is proposed for the type strain CBA4602T (=KACC 17668T =JCM 19530T).

Simultaneous Effect of Salinity and Temperature on the Neutral Lipid and Starch Accumulation by Oceanic Microalgae Nannochloropsis granulata and Chlorella vulgaris

− Because microalgae represent high growth rate than terrestrial plants, and it can accumulate significant lipid and carbohydrate content, and other bioactive compounds such as carotenoid and polyphenol in their body, it has been considered as one of the promising resources in bio-energy, and other industries. Although many studies has been performed about the microalgae-derived biochemical accumulation under various abiotic conditions such as different temperatures, salinities and light intensities, the studies about simultaneous effect of those parameters has rarely been performed. Therefore, this study focused on evaluation of simultaneous effect of different salinity (10, 30, 50 psu) and temperatures (20, 25, 30 °C) on the changes of biomass, lipid, starch and photosynthetic pigment accumulation. As results, the highest growth rate was achieved at 30 °C and 30 psu in the both algal cultures, and the photosynthetic pigment, chlorophyll a and total carotenoid content, were increased in a temperature-dependent manner. The accumulation of lipid and starch contents exhibited different aspects under different combinaCorresponding author: dkim@kbsi.re.kr, ikyeo99@jejunu.ac.kr 염분과 온도의 동시 영향에 따른 해양 미세조류 Nannochloropsis granulata와 Chlorella vulgaris의 중성지질 및 녹말 축적에 관한 연구 237 tions of temperature and salinity. From the results, it is suggested that the changes of microalgal lipid and starch accumulation under different salinities may be affected by the different temperatures.

Trans-1,3-diphenyl-2,3-epoxypropan-1-one, a chalcone derivative, induces apoptosis via ROS-mediated down-regulation of Bcl-xL in human leukemia HL-60 cells

The anticancer effects of trans-1,3-diphenyl-2,3-epoxypropan-1-one (DPEP), a chalcone derivative, were investigated in human leukemia HL-60 cells. Treatment of HL-60 cells with various concentration of DPEP resulted in a sequence of events characteristic of apoptosis, including loss of cell viability, morphological changes, and increased sub-G1 DNA content. We demonstrated that DPEP elevates reactive oxygen species (ROS) levels in HL-60 cells, and that the ROS scavenger N-acetylcysteine (NAC) could block DPEP-induced ROS generation and apoptosis. Western blot analysis revealed that DPEP inhibits Bcl-xL expression, leading to caspase-3 activation and poly-ADP-ribose polymerase (PARP) cleavage, thereby inducing apoptosis. However, NAC pre-treatment significantly inhibited the activation of caspase-3 and PARP cleavage and reduced Bcl-xL levels. These findings provide the first evidence that DPEP may inhibit the growth of HL-60 cells and induce apoptosis through a ROS-mediated Bcl-xL pathway.