Comparative Study on Nano-Sized 1 wt% Pt/Ce<Subscript>0.8</Subscript>Zr<Subscript>0.2</Subscript>O<Subscript>2</Subscript> and 1 wt% Pt/Ce<Subscript>0.2</Subscript>Zr<Subscript>0.8</Subscript>O<Subscript>2</Subscript> Catalysts for a Single Stage Water Gas Shift Reaction

Abstract  

A comparative study on nano-sized Pt/Ce_0.8Zr_0.2O₂ and Pt/Ce_0.2Zr_0.8O₂ catalysts in a single stage water gas shift (WGS) reaction was carried out. These catalysts were prepared by impregnating 1 wt% Pt on nano-sized cubic (Ce_0.8Zr_0.2O₂) and tetragonal (Ce_0.2Zr_0.8O₂) supports. Both catalysts have been applied to WGS under identical conditions to understand beneficial effect of cubic/tetragonal phases of Ce_(1 − x)Zr_(x)O₂. 1 wt% Pt/Ce_0.8Zr_0.2O₂ exhibited higher CO conversion than 1 wt% Pt/Ce_0.2Zr_0.8O₂. In addition, 1 wt% Pt/Ce_0.8Zr_0.2O₂ catalyst showed relatively stable activity with time on stream. The high activity/stability of 1 wt% Pt/Ce_0.8Zr_0.2O₂ catalyst was correlated to its higher Pt dispersion and easier reducibility.     

Rational Biosynthetic Engineering for Optimization of Geldanamycin Analogues

Tailor made : We report the rational biosynthesis of C15 hydroxylated non‐quinone geldanamycin analogues by site‐directed mutagenesis of the geldanamycin polyketide synthase (PKS), together with a combination of post‐PKS tailoring genes. Rational biosynthetic engineering allowed the generation of geldanamycin derivatives, such as DHQ3 illustrated in the figure, which had superior pharmacological properties in comparison to the parent compound.

     

Selective Production of H2 from Ethanol at Low Temperatures over Rh/ZrO2–CeO2 Catalysts

A series of Rh catalysts on various supports (Al₂O₃, MgAl₂O₄, ZrO₂, and ZrO₂–CeO₂) have been applied to H₂ production from the ethanol steam reforming reaction. In terms of ethanol conversion at low temperatures (below 450 °C) with 1wt% Rh catalysts, the activity decreases in the order: Rh/ZrO₂–CeO₂ > Rh/Al₂O₃ > Rh/MgAl₂O₄ > Rh/ZrO₂. Support plays a very important role on product selectivity at low temperatures (below 450 °C). Acidic or basic supports favor ethanol dehydration, while ethanol dehydrogenation is favored over neutral supports at low temperatures. The Rh/ZrO₂–CeO₂ catalyst exhibits the highest CO₂ selectivity up to 550 °C, which is due to the highest water gas shift (WGS) activity at low temperatures. Among the catalysts evaluated in this study, the 2wt% Rh/ZrO₂–CeO₂ catalyst exhibited the highest H₂ yield at 450 °C, which is possibly due to the high oxygen storage capacity of ZrO₂–CeO₂ resulting in efficient transfer of mobile oxygen species from the H₂O molecule to the reaction intermediate.     

Synthesis of mesoporous silica in acidic condition by solvent evaporation method

Both powder-type and film-type mesoporous silica materials have been prepared by using a sol-gel process in highly acidic, solvent-rich and mild conditions by solvent evaporation method. Powder mesoporous silica which has hexagonal arrays was well synthesized within only 10 minutes, and mesoporous film was formed on the glass plate within only several seconds by supramolecular interactions between the silicate species and surfactant-templates. In particular, the synthesis time was very short compared with that of hydrothermal synthesis owing to the solvent evaporation. This method has some characteristics different from the hydrothermal method such as the following. There is no precipitation because particles do not form in the solution before solvent evaporation, bulk powder is rigid, whereas that of hydrothermal synthesis is very soft, and mesoporous materials are synthesized in acidic condition. Solvent evaporation method for the synthesis of mesoporous materials is promising because the method is very simple and time-saving.     

Poly(t-butyl-3α-(5-norbornene-2-carbonyloxy)-7α,12α-dihydroxy-5β-cholan-24-oate-co-maleic anhydride) for a 193-nm photoresist

A copolymer of t-butyl-3α-(5-norbornene-2-carbonyloxy)-7α,12α-dihydroxy-5β-cholan-24-oate and maleic anhydride was synthesized as a matrix polymer for ArF excimer laser lithography. The polymer has an excellent transmittance at 193 nm and possesses good thermal stability up to 255°C. The resist formulated with the polymer showed better dry-etching resistance than the conventional KrF excimer laser resist for chlorine and oxygen mixed gas. A 0.15 μm line and space patterns were obtained at a dose of 18 mJ cm⁻² using an ArF excimer laser stepper.     

Quantum‐dots‐based detection of hepatitis C virus (HCV) NS3 using RNA aptamer on chip

BACKGROUND: Over 170 million people, more than 3% of the world's population, suffer from the hepatitis C virus (HCV) infection and the rate of death from liver‐related mortality to HCV has increased. In respect of this, the development of assays for biological imaging should be urgently considered as an essential factor in diagnosis. RESULTS: A novel HCV‐detecting technique using a nanoparticle‐supported aptamer probe was demonstrated. With the aid of nanoparticle quantum dots (QDs) with carboxyl group as an imaging probe, and 5′‐end‐amine‐modified RNA oligonucleotide as a capturing probe, target HCV NS3 was visually detected on chip. The QDs‐based RNA aptamer for HCV NS3 showed high selectivity and specificity against other protein such as BSA. The detection limit of HCV NS3 protein was 5 ng mL^?1 level. CONCLUSION: With a novel strategy for protein–aptamer interaction, the feasibility of applying QDs‐based fluorescent detection technique to HCV viral protein assay for the development of a protein biochip was demonstrated. This scheme of QDs‐mediated imaging with a target‐oriented specific RNA aptamer for the detection of infectious HCV diseases provides an efficient strategy and a promising new platform for monitoring applications. Copyright © 2010 Society of Chemical Industry     

AQP3 Increases Intercellular Cohesion in NSCLC A549 Cell Spheroids through Exploratory Cell Protrusions

Tumor cell aggregation is critical for cell survival following the loss of extracellular matrix attachment and dissemination. However, the underlying mechanotransduction of clustering solitary tumor cells is poorly understood, especially in non-small cell lung cancers (NSCLC). Here, we examined whether cell surface protrusions played an important role in facilitating the physical contact between floating cells detached from a substrate. We employed poly-2-hydroxyethyl methacrylate-based 3D culture methods to mimic in vivo tumor cell cluster formation. The suprastructural analysis of human NSCLC A549 cell spheroids showed that finger-like protrusions clung together via the actin cytoskeleton. Time-lapse holotomography demonstrated that the finger-like protrusions of free-floating cells in 3D culture displayed exploratory coalescence. Global gene expression analysis demonstrated that the genes in the organic hydroxyl transport were particularly enriched in the A549 cell spheroids. Particularly, the knockdown of the water channel aquaporin 3 gene (AQP3) impaired multicellular aggregate formation in 3D culture through the rearrangement of the actomyosin cytoskeleton. Moreover, the cells with reduced levels of AQP3 decreased their transmigration. Overall, these data indicate that cell detachment-upregulated AQP3 contributes to cell surface protrusions through actomyosin cytoskeleton remodeling, causing the aggressive aggregation of free-floating cells dependent on the property of the substratum and collective metastasis.     

Analysis of yeast and archaeal population dynamics in kimchi using denaturing gradient gel electrophoresis

Kimchi is a traditional Korean food that is fermented from vegetables such as Chinese cabbage and radish. Many bacteria are involved in kimchi fermentation and lactic acid bacteria are known to perform significant roles. Although kimchi fermentation presents a range of environmental conditions that could support many different archaea and yeasts, their molecular diversity within this process has not been studied. Here, we use PCR-denaturing gradient gel electrophoresis (DGGE) targeting the 16S and 26S rRNA genes, to characterize bacterial, archaeal and yeast dynamics during various types of kimchi fermentation. The DGGE analysis of archaea expressed a change of DGGE banding patterns during kimchi fermentation, however, no significant change was observed in the yeast DGGE banding patterns during kimchi fermentation. No significant difference was indicated in the archaeal DGGE profile among different types of kimchi. In the case of yeasts, the clusters linked to the manufacturing corporation. Haloarchaea such as Halococcus spp., Natronococcus spp., Natrialba spp. and Haloterrigena spp., were detected as the predominant archaea and Lodderomyces spp., Trichosporon spp., Candida spp., Saccharomyces spp., Pichia spp., Sporisorium spp. and Kluyveromyces spp. were the most common yeasts.     

A highly active catalyst, Ni/Ce–ZrO2/θ-Al2O3, for on-site H2 generation by steam methane reforming: pretreatment effect

The steam treatment effect has been investigated over the doubly impregnated catalyst, Ni/Ce–ZrO₂/θ-Al₂O₃, in steam methane reforming (SMR). The catalyst was remarkably deactivated by steam treatment but reversibly regenerated by H₂-reduction. XRD results showed that the steam treatment resulted in the formation of NiAl₂O₄ which is inactive for SMR but it was reversibly converted to Ni by the reduction. The reversible oxidation-reduction of Ni state was also evidenced by XPS and it was observed that the formation of NiAl₂O₄ is more favorable at higher temperature. It is most likely that the alumina support is only partially covered with Ce–ZrO₂ and most Ni directly interacts with θ-Al₂O₃ which would probably make easy formation of NiAl₂O₄ in the presence of steam alone. The results imply that, during the start-up procedure in SMR, too high concentration of steam could deactivate seriously Al₂O₃ supported Ni catalysts.     

Reduction of aflatoxins by Korean soybean paste and its effect on cytotoxicity and reproductive toxicity--part 1. Inhibition of growth and aflatoxin production of Aspergillus parasiticus by Korean soybean paste (Doen-jang) and identification of the active component

The inhibitory effect of methanol extract of Korean soybean paste on the mold growth and aflatoxin production of a toxigenic strain of Aspergillus parasiticus ATCC 15517 was studied using different concentrations of the extract in yeast-extract sucrose broth. While inhibition in mold growth due to increasing the concentration of the extract was observed, the more remarkable effect was the inhibition of aflatoxin production. Reduction of mycelial weight as a result of addition of the extract was observed to range between 1.5 to 12.9% while reduction of aflatoxin production quantified by high-performance liquid chromatography ranged from 14.3 to 41.7%. Five percent of the extract significantly reduced aflatoxin production at the end of the incubation period (P < 0.05), although the effect on mycelial growth was less pronounced. This study indicates that soybean paste could also be an effective inhibitor of aflatoxin production even though mycelial growth may be permitted. The main active component identified by gas chromatography-mass spectroscopy was linoleic acid.