Silica Transformations in the System PbO-SiO2

Mixtures of PbO and silicic acid were fired at 710°, 820°, and 910°C for periods up to 1000 hr in air. At each temperature cristobalite and tridymite crystallized rapidly, with the greatest development in samples with compositions of 1 mole PbO to 50 and 60 moles SO₂. At 820° and 91O°C tridymite continued to crystallize at the expense of cristobalite. At 710°C quartz formed, after a nucleation time of approximately 200 hr, at the expense of cristobalite and tridymite. The equilibrium assemblages were cristobalite and tridymite at 820° and 910°C and quartz and PbSiO₂ at 710°C. The results are interpreted in terms of the tentative phase relations outlined by Holmquist for the high-silica regions of binary silicate systems. Phase development curves and lattice parameter measurements characterize the initially formed cristobalite as a metastable solid solution containing approximately 2 mole % PbO. Equilibrium was approached by exsolution of PbO from the cristobalite structure.     

Effect of Impurities on Electrical Solid-state Properties of Barium Titanate

Results are presented in which BaTiO₂ single crystals with various impurity additions were grown and their effect on crystal quality, switching behavior, and electrical solid-state properties was investigated.     

PREDICTION OF PATHOLOGY FROM MAKE-A-PICTURE STORY (MAPS) TEST FIGURES.

INVESTIGATED HOW RELIABLY AND VALIDLY CLINICAL PSYCHOLOGISTS COULD EVALUATE THE PATHOLOGY STIMULUS VALUE OF THE MAKE-A-PICTURE STORY (MAPS) TEST FIGURES. 4 CLINICAL PSYCHOLOGISTS RATED THE 67 MAPS FIGURES ON 3 MAPS BACKGROUNDS IN TERMS OF HOW MUCH PATHOLOGY WOULD BE INDICATED BY THE USE OF THE FIGURE ON A PARTICULAR BACKGROUND. PATHOLOGY INDICATION (PI) SCORES WERE CALCULATED FOR ALL THE RELIABLY RATED FIGURES. THESE RATINGS WERE THEN COMPARED TO THE ACTUAL PERFORMANCES OF PATIENTS OF VARIOUS LEVELS OF PATHOLOGY. THE DATA INDICATE THAT THERE WAS LITTLE RELATIONSHIP BETWEEN THE PSYCHOLOGISTS' A PRIORI PI SCORES OF THE MAPS TEST FIGURES AND THE ACTUAL USE OF FIGURES BY THE PATIENTS. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

THE STUDY OF SAMPLING ERRORS IN FACTOR ANALYSIS BY MEANS OF ARTIFICIAL EXPERIMENTS.

2 POINTS OF VIEW ABOUT FACTOR ANALYSIS ARE OFFERED: (1) THE STATISTICAL, IN WHICH SAMPLING FLUCTUATIONS ARE THE RESULT OF THE SAMPLING OF PERSONS, AND (2) THE PSYCHOMETRIC, IN WHICH INDETERMINACIES RESULTING FROM FLUCTUATIONS IN WHAT IS MEASURED ARE EMPHASIZED. SEVERAL STUDIES SUGGEST THAT THE STANDARD ERROR OF A FACTOR LOADING DUE TO THE SAMPLING OF PERSONS IS ABOUT N-$M$UQ. THIS IS APPROXIMATELY TRUE FOR ANALYTICALLY ROTATED FACTORS. IT IS MORE NEARLY TRUE FOR LEAST-SQUARES ROTATIONS TO THE POPULATION, BUT THIS GENERALIZATION IS LIMITED BY THE LACK OF CONTROL OF THE ANGLES OF SEPARATION AMONG THE ROTATED FACTORS IN THE SAMPLE. EVIDENCE IS GIVEN CONCERNING THE INFLUENCE OF TYPE OF FACTORING, SIZE OF LOADING, AND METHOD OF FACTORING. THE DETERMINATION OF THE NUMBER OF FACTORS IS DISCUSSED. EVIDENCE FROM STUDIES OF PSYCHOMETRIC ERROR IS ALSO PRESENTED. (39 REF.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of seed polyphenols in berries from Vitis vinifera L. cv. Shiraz

Polyphenols extracted from the seeds of Vitis vinifera L. cv. Shiraz berries were monitored during berry development. Initially seeds were green, plump and had pliable seed coats, but beginning at veraison the seeds browned in colour, became desiccated and the seed coats hardened. Isolated polyphenols consisted of flavan-3-of monomers ((+)-catechin, (-)-epicatechin and (-)-epicatechin-3-O-gallate) and procyanidins. The procyanidins were maximal in the 3 weeks prior to veraison, increasing little during this period. The amounts of flavan-3-ol monomers increased 5-fold during this same period of time, indicating that the procyanidins and the flavan-3-ol monomers accumulate at different stages. Beginning at veraison, amounts of all polyphenols declined and changed in composition. The decrease in amount followed second-order kinetics. Polyphenol changes after veraison could be explained by oxidation and therefore, electron paramagnetic resonance (EPR) spectroscopy was used to follow the potential development of radical species in the developing seeds. Spectra consistent with a phenoxyl radical were observed in the developing seeds. The concentration of radicals remained low until veraison but then increased, reaching a maximum three weeks later, declining slowly thereafter. Changes in radical intensity together with other documented changes in the seed are consistent with an oxidative event occurring during fruit ripening.     

Resistance of Clostridium perfringens to Varying Degrees of Acidity during Growth and Sporulation

SUMMARY: Viable cells of each of 6 strains of Clostridium perfringens were exposed to 4 levels of acidity during phases of the growth cycle. The selected strains included 4 which had been recovered in association with food poisoning outbreaks and 2 strains not so associated. The growth media tested included Fluid Thioglycollate Medium, DS-sporulation medium and the CP-2V medium proposed by Hauschild.
The level of acidity, length of exposure of the cells, the growth medium employed and the phase in the growth curve influenced the survival of C. perfringens. Exposure of cells grown in DS-sporulation medium to buffers pH 6.0 had little effect on the survival over the 8-hr test period, with somewhat greater sensitivity of cells being demonstrated at pH 4.5. Exposure of cells, similarly produced, to buffer pH 1.0 or 2.0 was much more effective in reducing the percentage of survival, particularly during early log phase and at the onset of sporulation. Based on the 3 growth media utilized, calculated survival curves resulting from exposure of cells to pH 1.0 or 2.0 were erratic in shape, and percentage survival was almost universally less than 10%.
Source of the strain, whether food poisoning or non-food poisoning associated, appeared to have no significant effect on the acid resistance of the cells. The comparatively regular increase in the percentage of survivors after the initiation of sporulation suggests that spores exhibit a greater resistance to acid stress than vegetative cells.
Incubation at temperatures of 37° or O°C, during the time of treatment with the test buffers pH 1.0 or 2.0, produced no consistent change in the percentage of survivors when the cells were grown in FTG.     

NOVEL NONTHERMAL METHODS TO REDUCE VIBRIO VULNIFICUS IN RAW OYSTERS

Vibrio vulnificus is a foodborne pathogen associated with consumption of raw oyster. No scientific data is available on postharvest treatments of oyster by ultrasound, ozone, and organic acids. This study was designed to investigate the effects of these treatments on inactivation of V. vulnificus naturally present in the in-shell or half-shelled oysters. In in-shell oysters, these treatments were not effective in reducing the number of this pathogen. Half-shelled oysters treated with ultrasound, and ozone in 2% saline for 30 min had 1 and 1.5 log less V. vulnificus, respectively (p<0.05). Treatment of half-shelled oysters by 50 and 100% lemon juice, 5% citric acid, 10% citric acid, or vinegar for 30 min resulted in a significant reduction (2–4 log) in the numbers of V. vulnificus (p<0.05). Although these methods significantly reduced the population of V. vulnificus in raw oysters, they were not able to reduce the numbers of this pathogen to acceptable level (<3 MPN/g).     

A VISCOSITY MODEL FOR A COOKING DOUGH1

A five parameter semi-empirical model is developed describing the apparent viscosity of a cooking dough as a function of applied shear rate, temperature, and time-temperature history. Such a model will be useful in the mathematical simulation of the extrusion cooking process. Other factors which can affect the apparent viscosity of a cooking dough are also discussed. The viscosity model is verified and the constants evaluated for a typical dough by combining the results of Amylograph and capillary viscometer experiments.