Light attenuation in a semitransparent foam sheet-Thickness measurement for industrial use

An optical method for measuring the thickness of heterogeneous materials has been studied. The method is based on the light attenuation theory. A complete system has been constructed in order to demonstrate the applicability of the present method for industrial use. The experimental set-up consists of semiconductor lasers, focusing lenses, photo-diodes serving as a power meter and a personal computer with an A/D converter for data acquisition. Averaging of numerous measurements is required in the present method because the heterogeneous cell structure of the foam material yields large fluctuations in transmitted light levels. The fluctuations can be reduced to below 1% of the transmitted light power by 80 times averaging. The error of the measurement is considered to be a few tens of micrometers in thickness. The present system is capable of sampling data at a rate of 400 Hz and has been successfully applied to a manufacturing process.     

Syntheses of tetraoxaquaterene derivatives

Several new dimethyl and tetramethyl tetraoxaquaterenes, 3d and 3e , have been prepared in order to synthesize the oxygen analogues of porphyrin. The reaction between furan and a ketone using an acidic catalyst gave the cyclic tetramer, tetraquaterene, and oligomers. On the other hand, in the case of furan and an aldehyde, only linear oligomers were isolated. The condensation of furan-containing dimers with carbonyl compounds, both ketone and aldehyde, except formaldehyde, gave the tetraoxaquaterene. In the case of formaldehyde, the yield of cyclic tetramer was negligible.     

An electron microscopic study of the archaeal feast/famine regulatory protein 5. Fourier filtration of images

Microcrystals of the feast/famine regulatory protein (FFRP) pot0434017 (FL11) were prepared by sonicating larger crystals. Using the microcrystals a cryo-electron micrograph was obtained, which showed a hexagonal packing of cylinder-like assemblies of FL11. This micrograph was processed by selecting, in the Fourier space, spots reflecting the crystal lattice, thereby removing the noise. The microcrystal was not totally free from distortion, and cylinders in local clusters adopted slightly different orientations. Thus, 25 hexagonal units closest to the ideal, each containing a cylinder at the center surrounded by six others, were manually selected. The averaged image was further processed to yield a perfect six-fold symmetry. These processed images, and some of the original images too, show bridges connecting cylinders, each corresponding to two pairs of N-domains, protruding from the two cylinders and contacting between them in the X-ray structure.     

Determination of the Heat of Adsorption and Desorption of a Volatile Organic Compound Under Dynamic Conditions Using Fourier‐Transform Infrared Spectroscopy

Quantitative Fourier‐transform infrared spectroscopic analysis was used for the determination of adsorption capacity of a model volatile organic compound (VOC) under dynamic conditions. The analytical method used also offers the possibility of distinguishing between reversible and irreversible adsorption as well as further detection of adsorbed VOC transformation. The obtained adsorbed amounts have been used for the determination of the heat of adsorption and the activation energy of desorption using, respectively, isosteric and temperature programmed desorption methods. The approach has been applied to explore the potential use of local clay as an adsorbent material for VOC pollutants.     

Phase behavior of binary bilayer membrane of dipalmitoylphosphatidylcholine and stigmasterol

Journal of Thermal Analysis and Calorimetry - We investigated the phase behavior of a binary bilayer membrane of dipalmitoylphosphatidylcholine (DPPC) and stigmasterol (Stig) as a function of the...     

Switchable antenna: a star-shaped ruthenium/osmium tetranuclear complex with azobis(bipyridine) bridging ligands

A star-shaped Ru/Os tetranuclear complex, in which a central Os unit is linked to three peripheral Ru units by 4,4'-azobis(2,2'-bipyridine) (azobpy) bridging ligands, was prepared to examine the unique photodynamics regulated by its redox state. The Ru/Os tetranuclear complex exhibits Ru-based luminescence at 77 K, whereas the three-electron reduction (one for each azobpy) of the Ru/Os complex results in luminescence from the Os unit. The photoexcited state of the Ru/Os complex rapidly decays into low energy metal-to-ligand charge-transfer states, in which the excited electron is localized in the azobpy ligand in the form of azobpy(.-). Upon the one-electron reduction of the azobpy ligands, the above-mentioned low-energy states become unavailable to the photoexcited complex. As a result, an energy transfer from the Ru-based excited state to the Os-based excited state becomes possible. Ultrafast transient absorption measurements revealed that the energy transfer process consists of two steps; intramolecular electron transfer from the terminal bipyridine ligand (bpy(.-)) to form azobpy(2-) followed by a metal-to-metal electron transfer. Thus, the Ru/Os tetranuclear complex collects light energy into the central Os unit depending on the redox state of the bridging ligands, qualifying as a switchable antenna.     

Key role of the Lewis base position in asymmetric bifunctional catalysis: design and evaluation of a new ligand for chiral polymetallic catalysts

New chiral ligands for asymmetric polymetallic catalysts were designed on the basis of the assumption that the higher-order assembly structure is stabilized by modifying the modular unit. The designed ligands 6 and 7 contained a scaffolding cyclohexane ring with a Lewis base phosphine oxide directly attached to the scaffold. A module in the polymetallic complex contains two metals per ligand, and a stable 6-, 5-, 5-membered fused chelation ring system should be generated. Synthesis of these ligands is simple and high yielding, using a catalytic dynamic kinetic resolution promoted by the Trost catalyst as a key step. Ligand function was assessed in a catalytic asymmetric ring-opening reaction of meso-aziridines with TMSCN, a useful reaction for the synthesis of optically active beta-amino acids. The Gd complex generated from Gd(OiPr)3 and the ligand was a highly active and enantioselective catalyst in this reaction. Enantioselectivity was reversed compared to the previously reported d-glucose-derived catalyst containing the same chirality of the individual module. ESI-MS analysis and X-ray crystallographic studies indicate that the assembly state of the modules in the polymetallic catalysts differs depending on the chiral ligand. The difference in the higher-order structure stems from a subtle change (one carbon) in the position of the Lewis base relative to the Gd metal. The change in the higher-order structure of the polymetallic complex led to a dramatic reversal of the enantioselectivity and increased catalyst activity.