Formation of Lead Zirconate-Lead Titanate Solid Solutions

Formation of the Pb(Zr,Ti)O₃ solid solution in the system PbO-TiO₂-ZrO₂ was studied by chemical analysis and X-ray powder diffrac-tometry. Only PbTiO₃ and Pb(Zr,Ti)O₃ were found as reaction products. The following three elementary reactions seemed to be reasonable for the formation of the Pb(Zr,Ti)O₃ phase: PbO + TiO₂→ PbTiO₃, PbTiO₃+ PbO + ZrO₂→Pb(Zr_1-λTi_λ)O₃, and Pb(Zr_l-λTi_λ)O₃+ PbTiO₃→ Pb(Zr_1-λ'Ti_λ')O₃ (λ<λ').     

Numerical Simulation on Supersonic Flow in High-Velocity Oxy-Fuel Thermal Spray Gun

This paper analyzes the behaviour of coating particles as well as the gas flow both inside and outside of the High-Velocity Oxy-Fuel (HVOF) thermal spray gun by using a quasi-one-dimensional analysis and a numerical simulation. The HVOF gun in the present analysis is an axially symmetric convergent-divergent nozzle with the design Mach number of 2.0. From the present analysis, the distributions of velocity and temperature of the coating particles flying inside and outside of the HVOF gun are predicted. The velocity and temperature of the coating particles at the exit of the gun calculated by the present method agree well with the previous experimental results. Therefore, the present method of calculation is considered to be useful for predicting the HVOF gas and particle flows.     

Spaghetti Stickiness: Some Factors Influencing Stickiness and Relationship to Other Cooking Quality Characteristics

Spaghetti was processed in a semi-commercial scale laboratory press from a range of raw materials, dried by a low temperature (LT) and a high temperature (HT) drying cycle, and assessed for stickiness and other important cooking quality attributes in cooking waters of varying hardness. Cooked HT spaghetti was generally less sticky, more resilient, firmer, and exhibited lower cooking loss than corresponding LT spaghetti. As cooking water hardness increased spaghetti became stickier and cooking loss increased. Stickiness was influenced by cultivar, wheat class, raw material granulation and protein content, but was not related to sprout damage. Stickiness was significantly correlated to cooking loss, cooked weight, degree of swelling, compressibility, recovery, and firmness. However, even when all these factors were included in a step-up regression less than 50% of the variance in stickiness could be predicted.     

Purification of properties of Saccharomyces cerevisiae cystathionine β-synthase

Cystathionine β-synthase (β-CTSase), which catalyses cystathionine synthesis from serine and homocysteine, was purified to homogeneity from Saccharomyces cerevisiae. The molecular mass of the enzyme was estimated to be 235 kDa by gel filtration and 55 kDa by sodium dodecyl sulphate–polyacrylamide gel electrophoresis, indicating that it is a homotetramer. The N-terminal amino acid sequence of the enzyme perfectly coincided with that deduced from the nucleotide sequence of CYS4, except for the absence of initiation methionine. The purified β-CTSase catalysed cysteine synthesis from serine (or O-acetylserine) and H₂S. From this finding, we discuss the multifunctional nature and evolutionary divergence of S-metabolizing enzymes.     

HYDROLYSIS OF PHYTATE IN BROWN RICE-ADDED BREAD BY ADDITION OF CRUDE AND PURIFIED ASPERGILLUS NIGER PHYTASE PREPARATIONS DURING BREAD MAKING

Brown rice-added breads were prepared with and without crude and purified Aspergillus niger phytase preparations. By adding 30% (w/w) brown rice flour and no phytase preparation, the phytate (myo-inositol hexaphosphate; IP₆) content of the bread was increased and the loaf volume was reduced. The direct addition of a food-additive grade phytase preparation (3,000 U) resulted in a significant decrease in the IP₆ content. However, it collapsed the bread crust. The crude phytase preparation had significant protease and amylase activities. A simple chromatographic method for the separation of phytase activity from the protease and amylase activities was developed. By using purified phytase, the IP₆ content was reduced without any adverse effects on the rising of the bread, which indicates that protease and amylase may be responsible for the collapse of the crust by the commercial phytase preparation.

PRACTICAL APPLICATIONS

Phytate in unrefined cereals and beans lowers bioavailability of minerals. On the other hand, these materials are rich in health-promoting components. To reduce the phytate in them during processing, some commercially available phytase preparations are now used. However, we found that such preparation contains significant amylase and protease activities, which may cause adverse effect on the appearance and textural properties of final products. To solve these problems, a simple and inexpensive procedure for separation of phyatase from amylase and protease was developed in the present study. The purified phytase can reduce phytate in brown rice-added bread without adverse effect on rising of bread. These results would encourage prepare the phytase preparation in high purity in an industrial scale to improve nutritional value of unrefined cereal- and bean-based functional foods.     

Aerodynamic study on supersonic flows in high-velocity oxy-fuel thermal spray process

To clarify the characteristics of gas flow in high velocity oxy-fuel (HVOF) thermal spray gun, aerodynamic research is performed using a special gun. The gun has rectangular cross-sectional area and sidewalls of optical glass to visualize the internal flow. The gun consists of a supersonic nozzle with the design Mach number of 2.0 followed by a straight passage called barrel. Compressed dry air up to 0.78 MPa is used as a process gas instead of combustion gas which is used in a commercial HVOF gun. The high-speed gas flows with shock waves in the gun and jets are visualized by schlieren technique. Complicated internal and external flow-fields containing various types of shock wave as well as expansion wave are visualized.     

Effect of Nonequilibrium Condensation of Moist Air on the Boundary Layer in a Supersonic Nozzle

INTRODUCTIONMapstudies[1-13lonthecondensationshockwaveoccurringinthecaseoftherapidexpansionofmoistairorsteaminasupersonicnozzlehavebeenper-formed,andthecharacteristicsofcondensationshockwavhavenearlybeenclarified.Acondensationshockwavalsooccursinthebladepassageinasteamturbinel14'15].Suchacondensationshockwavethatinteractswiththeboundary1ayeronthesurfaceofthettirbineblade,affectsthellowinthebladepas-sageinasteamturbine.However,thefiowinthebladepaJssagewiththecondensationshockwaveisnotyetun…     

Propagation of Weak Pressure Waves against Two Parallel Subsonic Streams

In this paper, the characteristics of a pressure wave propagating against two parallel subsonic streams in a constant-area straight duct are investigated by one-dimensional analysis, two-dimensional numerical simulation, and experiments. Computations have been carried out by the two-dimensional Euler Equations using the Chakravarthy-Osher-type TVD scheme. Optical observations by the schlieren method as well as wall pressure measurements have been performed to clarify both the structure and the propagation velocity of pressure waves. The results show that the pressure wave propagating against the streams changes into a bifurcated pressure wave and the bifurcation occurs in the low speed streams. It is also found that the propagation velocity of the pressure wave obtained by the analysis and computation agrees well with the present experimental data.