Structure and properties of poly(vinyl alcohol)/κ‐carrageenan blends

Blends of a commercial atactic poly(vinyl alcohol) (a‐PVA) derived from vinyl acetate and κ‐carrageenan were prepared by mixing the aqueous solutions of both samples. Blend films prepared by casting were transparent. In the DSC curves of the blend films, the endothermic peaks shifted to lower temperature with an increase of the content of κ‐carrageenan. The Young's modulus and the strength at break increased with an increase of the content of a‐PVA. As the standing temperature of the blend solutions decreased, the gelation region increased also at high content of carrageenan. In the amorphous regions of blend films, a‐PVA and κ‐carrageenan were miscible. © 2001 Society of Chemical Industry     

Applying heat integration total site based pinch technology to a large industrial area in Japan to further improve performance of highly efficient process plants

“Area-wide pinch technology” which consists of R-curve analysis and Site Source Sink Profile (SSSP) analysis, was applied to Kashima industrial area, one of the biggest heavy chemical complexes in Japan. This case study demonstrates that despite the very high efficiency of the individual sites in the complex, there is a huge amount of energy saving potential through energy sharing among the various sites. In addition it was found that appropriate use of the available pinch technology tools and techniques allows an industrial area of enormous scale and complexity to be analysed conveniently. This has resulted in practical area-wide energy saving projects being proposed and implemented.     

微波活化法从甲烷合成乙烯

利用微波活化法从甲烷催化偶合合成了乙烯。在5% Pt/c Lot 86111催化剂情况下得到了3.65%甲烷转化率和近100%的乙烯选择性。同一催化剂在热反应条件下完全没有反应活性。     

High-Performance Induction Motor Drive System Using a PWM Inverter

A high-performance speed control system for cage induction motors is described which utilizes a PWM inverter. The effects of primary current coincidence and machine constant variation on system characteristics such as response time, torque precision, and operating noise were investigated. Based on the results obtained, new control methods have been devised; one varies the gain of the current controller in proportion to the primary frequency, and a second compensates for the slip frequency by using the deviation between the flux reference value and the actual value. Effectiveness of the compensation methods was confirmed in tests.     

Toxicity and tetramine contents of salivary glands from carnivorous gastropods

Salivary glands from 29 species of marine carnivorous gastropods in nine families were examined for lethal activity against mice and tetramine content. Mouse lethality was assayed by intravenous injection of buffer extracts into mice, and was detected in 14 species. Heat-stability tests confirmed that toxins in four species were thermolabile, while those in eight species were thermostable. Based on the tetramine contents determined by the colorimetric method using methanolic extracts, the thermostable toxins in seven species (Neptunea eulimatalamellosa, N. vinosa, N. arthritica, N. bulbacea, N. intersculpta f. pribiloffensis, N. intersculpta f. frater pilsbry and Hemifusus tuba) were considered to be tetramine contained at high levels (more than 900 micrograms/g salivary gland), but that in one species (Buccinum opisthoplectum) appeared to be a low-molecular-weight compound differing from tetramine. It is interesting that one (Hemifusus tuba) of the seven species containing high amounts of tetramine belongs to the family Melongenidae, although the other six Neptunea species are members of the family Buccinidae, as expected from previous studies.     

Determination of sucralose in foods by HPLC using pre-column derivatization

The development of a sensitive pre-column derivatization high-performance liquid chromatography (HPLC) method for determination of sucralose is reported. Sucralose is converted into a strongly ultraviolet (UV)-absorbing derivative, possessing strong absorption at 260 nm, by treatment with p-nitrobenzoyl chloride (PNBCl). Homogenized samples were dialyzed and washed with a Bond Elut ENV cartridge, then the eluate was evaporated to dryness and the residue was derivatized. Subsequently, the sucralose derivative was purified with hexane-ethyl actate (9:1) in a silica cartridge, and then the sucralose derivative was eluted with acetone. HPLC was performed on a phenyl column, using acetonitrile-water (73:27) as a mobile phase with UV detection (260 nm). The calibration curve was linear in the range of 1 microgram/mL to 50 micrograms/mL of sucralose. The recoveries of sucralose from eight kinds of foods spiked at the levels of 0.20 and 0.05 g/kg of sucralose were more than 76.2% with SD values in the range from 0.90% to 4.31%. The quantitative limit of the developed method was 0.005 g/kg for sucralose in samples.     

Numerical simulation of an arbitrarily ended asymmetrical slab waveguide by guided-mode extracted integral equations

The scattering phenomenon from an arbitrary-shaped end of a asymmetrical slab waveguide for the cases of TE and TM guided modes is simulated by means of boundary integral equations that are called guided-mode extracted integral equations. The integral equations that we derive can be solved by the conventional boundary-element method. Numerical results are presented for problems of three-layer asymmetrical waveguides with tilted ends. The reflection coefficient, reflected and scattered powers, and radiation patterns are calculated numerically for the cases of incident TE and TM guided modes.     

Novel circular-beam equalizing techniques that use graded-index fiber optics for a high-power laser diode

We demonstrate a novel method of equalizing a laser diode (LD) beam into a circular beam. This method uses the twist effect of graded index (GI) fiber optics. An asymmetric LD beam with beam qualities of M2 = 500 in the slow axis and M2 = 4 in the fast axis is converted successfully into a symmetric circular beam with a beam quality of M2 = 175. The circular-output beam with 92% coupling efficiency from the fiber input to the fiber output is obtained with a 5-m-long GI1200 (1200 means a core diameter of 1200 microm) fiber for a 2-W LD array. We extend the experiments to a higher-power source with higher asymmetric beam qualities of M2 = 3000 and M2 = 4. By slightly bending the GI10000 (10000 means a core diameter of 10,000 microm) fiber, we have succeeded in generating a symmetric beam with a improved beam quality of M2 = 2000. The average beam quality is preserved when the asymmetric ratio is not high, and the beam quality degradation ratio is investigated up to asymmetric ratios of 750.     

An investigation of the pH-activity relationships of Cex, a family 10 xylanase from Cellulomonas fimi: xylan inhibition and the influence of nitro-substituted aryl-beta-D-xylobiosides on xylanase activity

The kinetic parameters of Cex, a family 10 xylanase from Cellulomonas fimi, were determined at various pH levels using soluble birchwood xylan (BWX) as a natural polymeric substrate along with three other synthetic aryl-beta-D-xylobioside substrates. Using BWX, a high level of substrate inhibition was observed which increased with decreasing pH. In contrast, typical Michaelis-Menten-type profiles were obtained using the three aryl-beta-D-xylobiosides as substrates. The k(cat) values determined using o-nitrophenyl-beta-D-xylobioside did not change as the pH increased, whereas the k(cat) values obtained with BWX, phenyl-beta-D-xylobioside and p-nitrophenyl-beta-D-xylobioside decreased, suggesting that the presence of an ortho nitro group affects the activity displayed by Cex. These differences were not observed with XynB from Clostridium stercorarium F9, a member of the same family of xylanases as Cex. These results indicate that a careful evaluation is required when employing substituted aryl-beta-D-xylobiosides in the characterization of xylanases.