Enzymatic enrichment of arachidonic acid from Mortierella single-cell oil

An attempt was made to enrich arachidonic acid (AA) from Mortierella single-cell oil, which had an AA content of 25%. The first step involved the hydrolysis of the oil with Pseudomonas sp. lipase. A mixture of 2.5 g oil, 2.5 g water, and 4000 units (U) Pseudomonas lipase was incubated at 40°C for 40 h with stirring at 500 rpm. The hydrolysis was 90% complete after 40 h, and the resulting free fatty acids (FFA) were extracted with n-hexane (AA content, 25%; recovery of AA, 91%). The second step involved the selective esterification of the fatty acids with lauryl alcohol and Candida rugosa lipase. A mixture of 3.5 g fatty acids/lauryl alcohol (1:1, mol/mol), 1.5 g water, and 1000 U Candida lipase was incubated at 30°C for 16 h with stirring at 500 rpm. Under these conditions, 55% of the fatty acids were esterified, and the AA content in the FFA fraction was raised to 51% with a 92% yield. The long-chain saturated fatty acids in the FFA fraction were eliminated as urea adducts. This procedure raised the AA content to 63%. To further elevate the AA content, the fatty acids were esterified again in the same manner with Candida lipase. The repeated esterification raised the AA content to 75% with a recovery of 71% of its initial content.     

WDM passive network design for small wavelength-count in local area/home applications

Passive optical networks are attractive due to their enhanced reliability, reduced electrical power consumption, and small latency. This paper determines the feasibility of WDM (Wavelength Division Multiplexing) passive networks with low wavelength count for small environments such as buildings/homes from the viewpoint of the physical network configuration. After describing the general characteristics of WDM passive networks in the bus, star, and ring configurations, we elucidate the optical path losses to find design solutions when the three physical configurations are used to create small networks. It is concluded that the star configuration is the most feasible approach. The bus and ring are also feasible only for small areas and low wavelength counts.     

Heat and moisture transfer in sand molds containing water

A new model is proposed to express heat and moisture transfer in a sand mold containing water. The calculated values of temperature, moisture content, and gas pressure by the proposed modeling coincide well with reported experimental values. Furthermore, it is shown that the likelihood of blow holes is greatly increased with decreasing sand particle diameter because escape of vapor to the atmosphere becomes more difficult at lower permeability. Formerly Visiting Assistant Research Scientist at the University of Michigan on leave from Osaka University, Osaka, Japan     

Recrystallization by annealing in SiC amorphized with Ne irradiation

Alpha-silicon carbide was irradiated with Ne+ ions at room temperature to various fluences up to 7.5 x 10(20) Ne+ m(-2) and then isochronally annealed under observation with a transmission electron microscope. In all cases, thin regions were completely amorphized by irradiation and epitaxial growth occurred from the residual crystalline region by subsequent annealing. Crystal nucleation occurred with annealing at 1000 degrees C in the cases of 3.8 x 10(20) and 7.5 x 10(20) Ne+ m(-2) irradiation, and at 1100 degrees C in the cases of 1.3 x 10(20) and 2.3 x 10(20) Ne+ m(-2) irradiation. Growth or formation of bubbles was observed with annealing at 1000 degrees C after 1.3 x 10(20), 2.3 x 10(20), and 3.8 x 10(20) Ne+ m(-2) irradiation.     

Application of Aziridine to the Facile Synthesis of (±)-Supinidine and (±)-Trachelanthamidine

A facile synthesis of the pyrrolizidine alkaloids, (±)-supinidine (14) and (±)-trachelanthamidine (8) was achieved by employing aziridine as the reactive species.     

A study of the blast wave from deflagrative explosions

The research reported here is an experimental and theoretical study of the overpressures produced by unconfined vapour-cloud explosions (UVCE) in deflagration. Using the analogy of accidental explosions, the experiments were conducted in the open air using samples of hydrocarbons (propane, n-pentane and n-octane) in the range 0.31 – 313.0 kg by mass. The features observed in the overpressure profiles and their impulses were thoroughly studied by comparison with the results calculated from a simulation model that assumed a propagating flame that was a spherically expanding piston. This model was useful for determining the blast-wave parameters of ideal cases of UVCEs in deflagration. The behaviour of blast waves in dimensionless space was dependent on only the initial flame speed and was independent of mass, that is, it followed a kind of scaling law.     

Isotopic Study of N2O Decomposition on an Ion-Exchanged Fe-Zeolite Catalyst: Mechanism of O2 Formation

N₂O decomposition on an ion-exchanged Fe-MFI catalyst has been studied using an ¹⁸O-tracer technique in order to reveal the reaction mechanism. N₂ ¹⁶O was pulsed onto an ¹⁸O₂-treated Fe-MFI catalyst at 693 K, and the O₂ molecules produced were monitored by means of mass spectrometry. The ¹⁸O fraction in the produced oxygen had almost half the value of that on the surface oxygen, and ¹⁸O¹⁸O was not detected. The result shows that O₂ formation proceeds via the Eley–Rideal mechanism (N₂ ¹⁶O + ¹⁸O(a) N₂ + ¹⁶O¹⁸O).     

On-line monitoring of the density of linear low-density polyethylene in a real plant by near-infrared spectroscopy and chemometrics

This paper reports on-line monitoring of the density of linear low-density polyethylene (LLDPE) by near-infrared (NIR) spectroscopy and chemometrics. The on-line monitoring was carried out not only in a laboratory but also in a real plant. We composed an on-line monitoring system for molten polymers consisting of a Fourier transform near-infrared (FT-NIR) spectrometer, input/output (I/O) module, a personal computer, and a sampling cell that we developed. We first compared NIR spectra of LLDPE in the solid and melt states and then developed calibration models that predict the density using partial least squares regression (PLS). The sample sets for developing prediction models were collected for three months at the plant, and the density of LLDPE was continuously monitored on-line for another three months using the model. The standard error of prediction (SEP) for the on-line monitoring of the density of LLDPE at the plant was +/-2.1 mg/cm(3) (range: 0.91-0.95 g/cm(3)).     

HRTEM observations on composites of tin and tin dioxide nanoparticles dispersed on carbon nanotubes by single-atoms-to-clusters method

Nano-composites of tin and tin dioxide particles were synthesized on carbon nanotubes by the single-atoms-to-clusters (SAC) method, and their structures were investigated by high-resolution transmission electron microscopy. By changing the heat-treatment temperature during the SAC process, two different types of samples were obtained. The samples prepared around 450 K were aggregates of 2-4 nm-sized tin dioxide nanoparticles, and their size distributions on carbon nanotubes are in the range 20-40 nm. The other samples formed above 600 K had a core-shell structure of diameter 20-40 nm. The core and shell were made of tin single crystal and disordered oxidized tin, respectively. The thickness of the oxidized layers was ca. 4 nm.     

Role of active oxygen transients in selective catalytic reduction of N2O with CH4 over Fe-zeolite catalysts

Sharp NO and O₂ desorption peaks, which were caused by the decomposition of nitro and nitrate species over Fe species, were observed in the range of 520–673 K in temperature-programmed desorption (TPD) from Fe-MFI after H₂ treatment at 773 K or high-temperature (HT) treatment at 1073 K followed by N₂O treatment. The amounts of O₂ and NO desorption were dependent on the pretreatment pressure of N₂O in the H₂ and N₂O treatment. The adsorbed species could be regenerated by the H₂ and N₂O treatment after TPD, and might be considered to be active oxygen species in selective catalytic reduction (SCR) of N₂O with CH₄. However, the reaction rate of CH₄ activation by the adsorbed species formed after the H₂ and N₂O or the HT and N₂O treatment was not so high as that of the CH₄ + N₂O reaction over the catalyst after O₂ treatment. The simultaneous presence of CH₄ and N₂O is essential for the high activity of the reaction, which suggests that nascent oxygen species formed by N₂O dissociation can activate CH₄ in the SCR of N₂O with CH₄.