Application of an Acid Urease to Wine: Determination of Trace Urea in Wine

An improved method of urea detection having a sensitivity to 0.05 ppm, applicable to white wines, was developed by modifying Jansen's procedure. The urea concentration in many commercial bottled wines was found to be around 2 ppm. The method was utilized to the urea degradation by an acid urease which degraded naturally occurring urea of 0.5–2 ppm at the same reaction rate as that for the spiked urea of 30 ppm in the same white wine. Wine treatment with the acid urease also reduced ethyl carbamate formed by heating.     

Stability Analysis for Grid‐Connected LCL‐Type Inverter with Digital Control

A grid‐connected inverter is indispensable for photovoltaic power generation and smart grid systems, and it must be designed for stable operation. The impedance method based on the Nyquist criterion is often utilized to analyze the stability of grid‐connected inverter systems. The impedance method is based on the eigenvalues of the product of the inverter output admittance and the line impedance matrices in the frequency domain. However, the frequency characteristics have so far been derived only for inverters with analog control systems. A new frequency analysis method for inverters with digital control systems is proposed in this paper. First, a stability analysis example for a three‐phase LCL‐type inverter controlled digitally is shown and the results are compared and validated with those by simulation using a Saber simulator. Finally, they are also compared and validated with experimental results digitally controlled by a DSP‐based system.     

Production of Restructured Meat using Microbial Transglutaminase without Salt or Cooking

To produce restructured meat, microbial transglutaminase (MTGase) was evaluated for its ability to introduce covalent crosslinks between protein molecules. Pork muscle cubes were mixed with MTGase and held at 5°C for 2 hr for the enzyme reaction. Restructured products were analyzed for binding strength without cooking. MTGase treatment resulted in effective binding of meat pieces provided there was addition of salt (NaCl). To ensure proper binding without NaCl, some food proteins with MTGase were also investigated. Meat cubes in combination with MTGase and sodium caseinate showed acceptable bind, and sodium caseinate appeared to be a superior substrate for the crosslinking to meat proteins than soy protein, whey protein, or gelatin. These results suggest a useful method for producing restructured meat which can be distributed in the raw, chilled state.     

Characterization of Common Squid Using Several Freshness Indicators

Changes in several components and properties were examined to find appropriate indicators of freshness of common squid during storage at 0°C, 5°C and 10°C. Total viable counts of bacteria, pH and volatile basic nitrogen did not change significantly during 2 wk storage at 0°C. Unlike usual fish meat, K value in squid muscle changed very quickly, but Hx/AMP ratio was a better indicator. Agmatine increased before initial decomposition started but was not suitable as an early freshness indicator. Free basic amino acids, arginine and ornithine also changed rapidly. Basic amino acids such as arginine and ornithine appeared to be appropriate indicators of freshness of common squid.     

Design and scheduling for flexible manufacturing cells with automatic set-up equipment

A flexible manufacturing cell (FMC) has become of major interest recently as a new machining unit for low-volume, variety production. However, set-up operations for workpieces have not yet been automated in the usual FMC. In this paper, the design and scheduling problems for FMC with automatic set-up equipment are discussed. The FMC consists of a machining centre, an industrial robot, a loading-unloading station and an index-pallet changer. First, the design and control system of the FMC is explained. Then a scheduling algorithm is developed to achieve the minimum total production time in order to operate the FMC effectively. As this FMC has finite buffer spaces on the index-pallet changer, this model can be regarded as a two-machine flow-shop problem with finite buffer spaces. Next, an algorithm for determining the optimum number of buffer spaces is constructed to design the FMC using the results of scheduling. Finally, a numerical example is given for demonstrating the effectiveness of the proposed algorithms.     

EQUILIBRIUM DISTRIBUTION OF PALLADIUM(I I) BETWEEN HYDROCHLORIC ACID SOLUTION AND A MACROMOLECULAR RESIN CONTAINING TRI-n-OCTYLAMINE

ABSTRACT

Studies have been conducted on the sorption characteristics of palladium (II) from hydrochloric acid media with a macromolecular resin containing tri-n-octylamine (TOA). Sorption equilibrium of Pd (II) on the TOA-impregnated sorbent can be expressed by a simple ion-exchange reaction between a tetrachloro complex of Pd (II) in the aqueous phase and an amine salt in the sorbent as follows:

where the equilibrium constant was found to be 6.98x10⁴ kg/dm³.

The elution of Pd (II) from the metal-loaded sorbent was also examined. Elution can be attained with either hydrochloric acid or aqueous ammonia: in particular, the latter gave a high elution ratio even at a concentration less than 1M. The effect of the pore diameter of the macromolecular resins on the Pd(II) sorption was also studied and two methods for preparating impregnated sorbent were examined.     

Bioluminescence microscopy using a short focal‐length imaging lens

Bioluminescence from cells is so dim that bioluminescence microscopy is performed using an ultra low‐light imaging camera. Although the image sensor of such cameras has been greatly improved over time, such improvements have not been made commercially available for microscopes until now. Here, we customized the optical system of a microscope for bioluminescence imaging. As a result, bioluminescence images of cells could be captured with a conventional objective lens and colour imaging camera. As bioluminescence microscopy requires no excitation light, it lacks the photo‐toxicity associated with fluorescence imaging and permits the long‐term, nonlethal observation of living cells. Thus, bioluminescence microscopy would be a powerful tool in cellular biology that complements fluorescence microscopy.     

Internal friction of powder metallurgy (P/M) and ingot metallurgy (I/M) Al–Fe alloys at elevated temperature

Low-frequency internal friction measurements have been carried out on the powder metallurgy (P/M) and ingot metallurgy (I/M) Al–Fe alloy. Internal friction peaks can be seen at about 820–830 K and 530–620 K in the I/M alloys, but not in the P/M alloys. The former is probably due to the grain-boundary relaxation and the latter to recrystallization. Activation energies for the grain-boundary relaxation are estimated to be in two ranges: one is between 100 and 130 kJ mol–1 and the other is between 200 and 210 kJ mol–1, according to the iron content and fabrication processes. The high activation energy is given by the low iron content I/M alloys having a bamboo-like grain. It is suggested that such a difference in the activation energy is due to whether or not the solute iron diffuses into the grain boundary to lower the grain boundary energy.     

Oxygen-Sensor-Based Simple Assay of Histamine in Fish Using Purified Amine Oxidase

Oxygen consumption was measured by an oxygen sensor after addition of purified fungal amine oxidase to fish extracts. The oxidation of histamine to imidazoleacetaldehyde proceeded stoichiometrically. Based on the equimolar relationship between histamine and oxygen consumption, histamine was determined selectively by the oxygen sensor. Neither sample pretreatment removing interfering materials nor daily calibration by histamine standard was required. Histamine contents in scombroid fish were determined rapidly with good accuracy. AOAC and oxygen sensor methods showed a very high correlation (r=0.999, n=6).