Gelation Properties of Ovalbumin as Affected by Fatty Acid Salts

The physicochemical properties of heat-induced ovalbumin (OVA) gels containing fatty acid salts (FAS) were investigated. Water-holding ability and transparency markedly increased in the presence of sodium caprate or sodium laurate. At 9% of the protein concentration transparent and hard gels formed; at 7%, transparent and soft gels formed. Scanning electron microscopy showed that the transparent gels had a more homogeneous structure than turbid gels without FAS. Differential scanning calorimetry indicated that denaturation temperature of OVA was decreased and the peaks became broader after addition of FAS.     

11B and 27Al Nuclear Quadrupole Interactions in SiO2-B2O3-Al2O3-R2O Glass Systems

Quadrupole interactions of ¹¹B and ²⁷Al in SiO₂-B₂O₃-Al₂O₃-R₂O glass systems were investigated to determine the structure of these glasses, which should be amenable to chemical strengthening. The ratio of BO₄ units to BO₃ units approached unity as the R₂O/Al₂O₃ ratio for compounds having fixed B₂O₃ contents approached unity. Nuclear quadrupole coupling constants ( e²Qq/h =2.73 to 2.93 MHz) were measured for the NMR spectra of ¹¹B triangles. The line shapes of ²⁷Al spectra varied with chemical composition, but a few glasses exhibited ²⁷Al line shapes similar to those of the AlO₄ triclusters in SiO₂-Al₂O₃-Na₂O glasses. Compositional trends in the formation of BO₄ and AlO₄ were deduced from the NMR spectra.     

Comment on the equivalence condition of optimal control problems

Given a general non-linear plant, a method is presented for designing model reference feedback controllers for the plant. It is shown that the feedback controllers produced will guarantee prespecified closed-loop properties if the error between the plant and model lies within computable bounds. In particular, an upper bound on the tracking error is established and conditions are given that ensure closed-loop stability.     

The use of clipped input information in multidimensional cross-correlation for estimating Wiener-like kernels of non-linear systems

While the measurement of Wiener-like kernels by multidimensional input-output cross-correlation is a well-known non-parametric approach to non-linear system identification, we propose here a simplifying kernel estimation scheme; rather than using the white-noise signal that is actually applied to stimulate the system, the present method uses a clipped information (that is, two- or three-level quantization) of the continuous-level test input for computing the cross-correlation. This greatly reduces the computational requirement without disturbing the generality of actual test input which may be gaussian. The statistical variance of the kernel estimation is discussed in comparison with other algorithms. Certain non-statistical errors may be incurred using this approach, but are thought to be minor in most applications. A special emphasis is given to the problem of choosing optimal procedural parameters for ternary quantization in the case of white gaussian input.     

Further Studies on the Roles of the Head and Tall Regions of the Myosin Molecule in Heat-induced Gelation

Heat induced gelation properties of the two proteolytic fragments of myosin, heavy (HMM) and light meromyosin (LMM), were studied by rigidity measurement in a band type viscometer and by a direct examination using a scanning electron microscope. A heat induced network forming ability for both LMM and HMM was found in 0.6M KCl at a pH 6.0. LMM produced gels corresponding to a reversible helix-coil transition at temperatures ranging from 40–70°C, with little evidence of aggregation as assessed from a turbidity change of the system. Contrary, HMM associated irreversibly producing a gel with increased rigidity at pH 5.0 and a salt concentration of 0.1 M. Oxidation of SH-groups appeared to be involved only in HMM and not in LMM gelation process.     

Relative Roles of the Head and Tail Portions of the Molecule in Heat-Induced Gelation of Myosin

Myosin molecules are cleaved by chymotrypsin digestion into two fragments: subfragment 1, which originates from the globular heads of myosin, and the myosin rod, which originates from the helical tail of the myosin molecule. The heat-induced gelation of these subfragments was compared to that of intact myosin by measuring rigidity, turbidity, and other physico-chemical characteristics of each system. Two features of the heat-induced gelation of myosin, aggregation and three-dimensional network formation were found to be imparted by the subfragment 1 and the rod, respectively. The former involves disulfide exchange and the latter relates to conformational changes arising from a partially irreversible helix-coil transition during heating. Possible relationships are suggested between these physicochemical changes of the myosin head and tail regions upon heating and the heat-induced gelation of myosin.     

Quantitative Analysis of Monoclinic-Stabilized Cubic ZrO2 Systems by X-Ray Diffraction

An equation for a nonlinear calibration curve of volume fraction vs integrated intensity ratio is presented for monoclinic-stabilized cubic ZrO₂ systems containing YO_1.5, CaO, and MgO. A parameter in the equation was evaluated theoretically and is given for a range of cubic solid solution compositions.