Binding of Taurocholate by Pectin in the Presence of Calcium Ions

Binding of taurocholate by pectin was examined in vitro, using low-methoxyl pectin and calcium lactate. Water in calcium pectate gel was partially separated from the gel by filtration through a glass-filter. Taurocholate bound by pectin was calculated after measurement of taurocholate in the filtrate by the UV absorption method. The amount of taurocholate bound by pectin increased linearly with increase in pectin concentration but independent of time. One gram pectin bound a maximum of 6.0 μmole of taurocholate.     

Comparison of Transparent Gels with Turbid Gels Prepared from Egg White: Creep Analysis of Gels

Egg white from which the precipitate occurring during dialysis against water had been removed gave a transparent gel on heating at lower salt concentrations and pH 3.54. The addition of NaCl or a shift of pH from 3.54 to 4.50 brought about the turbid gels. Creep analyses of these transparent and turbid gels were done using a four-element mechanical model. The instantaneous elastic modulus, E₀, Newtonian modulus, ηn and retarded viscoelastic moduli, E₁ and η₁ increased with NaCl up to 125 mM and then decreased with increase in NaCl concentration at pH 3.54. At 125 mM NaCl and pH 3.54, a translucent gel was obtained. E₀ and η₁ decreased with the temperature of the gel, while E₁ and η₁did not change depending of temperature.     

Toxic Compounds Formed on Prolonged Heating of Citrinin under Watery Conditions

Citrinin was partially decomposed by heating under aqueous conditions at 90°C for > 10 min and a group of degraded compounds (Group I) was detected by TLC. At 100°C and 110°C, citrinin disappeared rapidly, and the cytotoxicity of the samples increased with prolonged heating. At 120°C, citrinin disappeared more rapidly while TLC spots of Group I compounds also diminished upon >20 min heating and a new group of compounds (Group II) appeared. Cytotoxicity decreased rapidly at > 120°C and was eliminated after 10 min at 130°C. Group I appeared to contain toxic compound(s) but Group II did not. Heating citrinin under conditions similar to cooking may cause formation of additional cytotoxic compounds.     

High surface area solids obtained by intercalation of iron oxide pillars in montmorillonite

When montmorillonite is dispersed in aqueous solutions of trinuclear acetato-hydroxo iron(III) nitrate, [Fe₃(OCOCH₃)₇OH]NO₃, the interlayer cations of the montmorillonite are exchanged with the partially hydrolyzed trinuclear acetato complex ions. On heating the exchanged complex ions are converted into iron oxide pillars which keep the silicate layers apart and form micropores between the layers. The resulting product has a basal spacing of 16.7 Å and a specific surface area of about 300 m²/g at 500°C. Adsorption isotherms for various vapors on the product have been measured.     

A Proposal of Identifying Optimized Layout of Devices in Electromagnetic Resonant Coupling Type Wireless Power Transfer System

Recently, a system for wireless power transfer (WPT) using electromagnetic resonant coupling has been evaluated and developed for practical applications such as a wireless charge system for automobiles or electronic devices. However, the efficiency of an electromagnetic resonant coupling type WPT system with LC resonators is greatly affected by the layout of the LC resonators allocated in the system. This means that there is an optimum layout for the LC resonators for transferring wireless power at higher efficiency. This paper presents a new method for identifying the optimum layout for the LC resonators in a WPT system. One of the key ideas is that the problem of finding the optimum layout is replaced by the problem of calculating the equivalent current sources in the LC resonators. The amplitude of the equivalent current sources can be calculated to solve ill‐posed system equations by using inverse analysis. First, the proposed method is described. The system equations to be solved are formulated by means of equivalent circuit techniques. Second, the proposed method is applied to a simplified model to identify the optimum layout for the LC resonators in a WPT system. Then, the results found using the proposed method are verified by comparing the ratio of receiving power with the identified layout and without the LC resonator. Finally, in order to verify the validity of the proposed method, the calculated results are compared with the experiment results using the same model.     

Nature and Thermal Evolution of Amorphous Hvdrated Zirconium Oxide

The thermal behavior of amorphous hydrated zirconium oxide and its coprecipitates with other oxides was studied. Solid solution with a limit of solubility seems to exist in the amorphous coprecipitates. A relation with the high-temperature solid solution was established. The structure of the amorphous zirconia was studied by X-ray and neutron diffraction; a thin plate model related to the structure of tetragonal zirconia is proposed. Heating the precipitates in an oxygen-free atmosphere produced a black nonstoichiometric oxide and stabilization of the tetragonal form.     

Rheological Properties of Heat-Induced Ovalbumin Gels Prepared by Two-step and One-step Heating Methods

Ovalbumin gave a transparent solution, transparent gel, or opaque gel on heating at low ionic strength, but a turbid gel, or turbid suspension at high ionic strength (one-step heating). The ovalbumin solution, once heated at low ionic strength, gave a transparent gel with a second heating at high ionic strength (two-step heating). Textural parameters of hardness and adhesiveness, viscoelastic parameters from creep curves, breaking energy and water-holding capacity of these gels were measured. Transparent gels by the one- or two-step heating were firm and elastic and had high water-holding capacity. Turbid gels by one-step heating were soft and less elastic and had low water-holding capacity. The relationship between gel properties and structure was discussed.     

PURIFICATION OF AMINOPEPTIDASE FROM THE JAPANESE CLASSIFIED BARLEY FLOUR

In a search for biologically active materials from the classified barley flour produced in Japan an aminopeptidase activity was identified. In this paper, the purification of aminopeptidase is described. The activity of the enzyme was monitored using L-leucine-p-nitroanilide as the substrate. After extraction using 20 mM sodium acetate buffer, pH 5.5, from the 95–75% classification flour, ammonium sulfate fractionation was performed between 30 and 50% saturation. The aminopeptidase was then purified about 160-fold to homogeneity as assessed by HPLC using the following sequential chromatography steps: hydrophobic interaction chromatography, Sephacryl S-200HR gel chromatography, DEAM-ion exchange chromatography, hydroxylapatite chromatography, Sephacryl S-100HR gel chromatography. The molecular weight of this enzyme was estimated as 62 kDα by size exclusion HPLC. The enzyme had a K_m value of 0.22 mM and α pH optimum of 7.0.     

Thermally Induced Epitope Regions of Ovalbumin Identified with Monoclonal Antibodies

To identify the structural regions of the ovalbumin molecule that change during heat denaturation, we used monoclonal antibodies that reacted specifically with the soluble heat-denatured ovalbumin as probes. Five monoclonal antibodies recognizing different epitopes of the denatured ovalbumin were produced. Through the isolation and sequence analysis of the peptides derived from ovalbumin that reacted with the monoclonal antibodies, five parts of the ovalbumin molecule were identified as the regions that change structurally and provide new epitopes during heat denaturation. These findings could be useful information in understanding the structural properties of heat-denatured ovalbumin.     

Preparation of Heat-induced Transparent Gels from Egg White by the Control of pH and Ionic Strength of the Medium

Egg white was dialyzed against distilled water or diluted with water, and the precipitates formed were removed by centrifugation. The supernatant gave a transparent gel after being heated at an acidic pH (2–4). At other regions of pH, except for the highly alkaline region, the gel or suspension was turbid upon heating. Insufficient centrifugation of the dialyzed egg white or the addition of NaCl to the supernatant after centrifugation resulted in a turbid gel on heating at even acidic pH. The removal of the slight precipitate formed at low ionic strength and the maintenance of low ionic strength during heating were both necessary for production of a transparent gel.