Dodecacarbonyltriosmium catalysed formation of bis(4-N,N-dimethylaminophenyl)methane from N,N-dimethylaniline

Os₃(CO)₁₂ catalyses the conversion of NMe₂Ph to (4-NMe₂C₆H₄)₂CH₂ and NHMePh in refluxing N,N-dimethylaniline. This reaction is similarly catalysed by H₄Os₄(CO)₁₂, while (4-NHMeC₆H₄)₂CH₂ may be obtained from NHMePh. In this case, however, NMe₂Ph and NH₂Ph are also formed, and after longer reaction times mixed products of type (4-NRR′C₆H₄)₂CH₂ (R or R′ = H or Me) are obtained. The formation of H₃Os₃(CH)(CO)₉ indicates methyl transfer from nitrogen to osmium which may be a key step in the catalysis, but it does not appear that clusters are essential since Fe(CO)₅ and Cr(CO)₆ are also weakly active.     

Culture medium optimization for acetic acid production by a persimmon vinegar-derived bacterium

A new acetic acid-producing microorganism, Acetobacter sp. RKY4, was isolated from Korean traditional persimmon vinegar, and we optimized the culture medium for acetic acid production from ethanol using the newly isolated Acetobacter sp. RKY4. The optimized culture medium for acetic acid production using this microorganism was found to be 40 g/L ethanol, 10 g/L glycerol, 10 g/L corn steep liquor, 0.5 g/L MgSO₄·7H₂O, and 1.0 g/L (NH₄H₂PO₄. Acetobacter sp. RKY4 produced 47.1 g/L of acetic acid after 48 h of fermentation in a 250 mL Erlenmeyer flask containing 50 mL of the optimized medium.     

Chiral Co(III)(salen)-catalysed hydrolytic kinetic resolution of racemic epoxides in ionic liquids

In the chiral Co(III)(salen)-catalysed HKR of racemic epoxides, in the presence of ionic liquids, Co(II)(salen) complex is oxidised without acetic acid to catalytically active Co(III)(salen) complex during reaction and, moreover, this oxidation state is stabilised against reduction to Co(II) complex which enables the reuse of the recovered catalyst for consecutive reactions without extra reoxidation.     

Highly sensitive signal detection of duplex dye-labelled DNA oligonucleotides in a PDMS microfluidic chip: confocal surface-enhanced Raman spectroscopic study

Rapid and highly sensitive detection of duplex dye-labelled DNA sequences in a PDMS microfluidic channel was investigated using confocal surface enhanced Raman spectroscopy (SERS). This method does not need either an immobilization procedure or a PCR amplification procedure, which are essential for a DNA microarray chip. Furthermore, Raman peaks of each dye-labelled DNA can be easily resolved since they are much narrower than the corresponding broad fluorescence bands. To find the potential applicability of confocal SERS for sensitive bio-detection in a microfluidic channel, the mixture of two different dye-labelled (TAMRA and Cy3) sex determining Y genes, SRY and SPGY1, was adsorbed on silver colloids in the alligator teeth-shaped PDMS microfluidic channel and its SERS signals were measured under flowing conditions. Its major SERS peaks were observable down to the concentration of 10(-11) M. In the present study, we explore the feasibility of confocal SERS for the highly sensitive detection of duplex dye-labelled DNA oligonucleotides in a PDMS microfluidic chip.     

Use of a photocatalytic membrane reactor for the removal of natural organic matter in water: Effect of photoinduced desorption and ferrihydrite adsorption

The photocatalytic degradation of natural organic matter (NOM) would be an attractive option in the treatment of drinking water. The performance of a submerged photocatalytic membrane reactor (PMR) was investigated with regard to the removal of NOM and the control of membrane fouling. In particular, this work focused on the adsorption and desorption of humic acids (HA) and lake water NOM at the surface of TiO₂ photocatalyts and ferrihydrite (FH) adsorbents in the PMR for water treatment. The addition of FH particles with a large sorption capacity helped remove the NOM released from TiO₂ particles, but FH suspended in water affected the photocatalysis of lake water NOM with a low specific UV absorbance (SUVA) value. To prevent the UV light being scattered by FH without any photocatalytic activity, FH particles were attached to a submerged microfiltration (MF) membrane, which contributed to a greater removal of NOM during long-term PMR operation. The further removal of NOM from aqueous solution was achieved due to the synergistic effect of TiO₂ photocatalysis and FH adsorption in PMR while minimizing the influence of photoinduced desorption of NOM. No significant membrane fouling occurred when the submerged PMR was operated even at high flux levels (>25 L/m² h), as long as photocatalytic decomposition took place.     

Secretion of adenylate kinase 1 is required for extracellular ATP synthesis in C2C12 myotubes

Extracellular ATP (exATP) has been known to be a critical ligand regulating skeletal muscle differentiation and contractibility. ExATP synthesis was greatly increased with the high level of adenylate kinase 1 (AK1) and ATP synthase beta during C2C12 myogenesis. The exATP synthesis was abolished by the knock-down of AK1 but not by that of ATP synthase beta in C2C12 myotubes, suggesting that AK1 is required for exATP synthesis in myotubes. However, membrane-bound AK1beta was not involved in exATP synthesis because its expression level was decreased during myogenesis in spite of its localization in the lipid rafts that contain various kinds of receptors and mediate cell signal transduction, cell migration, and differentiation. Interestingly, cytoplasmic AK1 was secreted from C2C12 myotubes but not from C2C12 myoblasts. Taken together all these data, we can conclude that AK1 secretion is required for the exATP generation in myotubes.     

Parametric study on impinging-jet liquid sheet thickness distribution using an interferometric method

 The effects of several influencing parameters on the thickness distribution of a liquid sheet formed by two impinging jets are examined using a simple interferometric method which can provide sharp and clear fringe images in spite of very simple optical setup. The parameters changed in this study are the impinging angle, orifice diameter, liquid jet velocity, and liquid viscosity. The experimental results are compared with existing theoretical predictions. A larger impinging angle, smaller orifice diameter, and a higher azimuthal angle are found to result in thinner liquid sheets, although jet velocity itself does not have any effect on the sheet thickness. Higher viscosity, on the other hand, is found to yield a thicker liquid sheet, which has not been considered in the theoretical analysis so far. The theoretical models used for comparison predict the same trend as the experimental results, but the thickness values are overestimated at low azimuthal angles. This discrepancy is gradually lessened as the azimuthal angle is increased. More refined theoretical modeling that decreases this difference and includes the effect of physical properties of liquid is necessary. Received: 26 May 2000/Accepted: 8 November 2000     

Laser cleaning of steel for paint removal

Paint removal is an important part of steel processing for marine and offshore engineering. For centuries, a blasting techniques have been widely used for this surface preparation purpose. But conventional blasting always has intrinsic problems, such as noise, explosion risk, contaminant particles, vibration, and dust. In addition, processing wastes often cause environmental problems. In recent years, laser cleaning has attracted much research effort for its significant advantages, such as precise treatment, and high selectivity and flexibility in comparison with conventional cleaning techniques. In the present study, we use this environmentally friendly technique to overcome the problems of conventional blasting. Processed samples are examined with optical microscopes and other surface characterization tools. Experimental results show that laser cleaning can be a good alternative candidate to conventional blasting.