Auger electron intensity variations in oxygen-exposed large grain polycrystalline silver

Auger electron spectroscopic studies of the grains in oxygen-charged polycrystal-line silver show significant intensity variations as a function of crystallographic orientation. These intensity variations were observed by studies of the Auger images and line scans of the different grains (randomly selected) for each silver transition energy. The results can be attributed to the diffraction of the ejected Auger electrons and interpreted by corresponding changes in the electron mean-free path for inelastic scattering and by oxygen atom accumulation in the subsurface. The subsurface (second layer) octahedral sites increased in size because of surface relaxation and serve as a stable reservoir for the dissolved oxygen

Studies on the alimentary tract of Merino sheep in South Africa. XV. The influence of different factors on the rate of cellulose digestion in the rumen and in ruminal ingesta as studied in vitro

(1) The rate of cellulose digestion in ruminal ingesta was studied both in vivo and in vitro by a new technique in which cotton threads were used as test material. (2) It was found that the rate of cellulose digestion was markedly influenced by the diet. (3) The appetite for either lucerne or grass hay was directly affected by the rate of cellulose digestion. (4) On a basic diet of poor quality grass hay both cellulose digestion and appetite were stimulated by small amounts of sugar but markedly depressed by excessive amounts. More sugar could be tolerated if protein was also given. Optimal cellulose digestion necessitated a balance between readily available carbohydrate and protein. (5) Excess protein suddenly introduced after a period on a diet low in both protein and carbohydrate caused marked inhibition of cellulose digestion and inappetence. One case of sudden death was possibly associated with ammonia poisoning.The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

One HACCP, two approaches: experiences with and perceptions of the Hazard Analysis and Critical Control Points (HACCP) food safety management systems in the US and the EU

This paper explores the differences in the use of the Hazard Analysis Critical Control Point (HACCP) system to manage food safety risks in the food chain from farm to fork in the EU and the US. In particular, this paper investigates the current uses and potential expansion of HACCP as a mechanism for the delivery of safe agricultural products, particularly safe produce. It considers not only whether HACCP systems are the best mode of governance for delivering safe food, and describes why HACCP has achieved an important role in the regulatory framework that governs food safety, but asks why this role is different in the EU and US. Within the EU, HACCP is compulsory at all stages of the food chain other than primary production, whereas the mandatory use of HACCP in the US is less widespread. However, the empirical work found that HACCP is being used by businesses in both the EU and US as a basis for organizing their business, even when not required by regulation. Using data derived from semi-structured interviews with regulatory actors in the EU and US, this paper argues that the different approach to HACCP is a result of differing ideas about the role that it plays in the governance of food safety, and the different concepts of the role of regulation in securing safe food. Finally, the paper explores the difficulties of utilizing HACCP to manage produce safety risks, and raises further challenges that must be met in order to ensure that HACCP can successfully fulfill its potential as a governance mechanism

Studies on the alimentary tract of the merino sheep in South Africa. XVI. The fate of nitrate in ruminal ingesta as studied in vitro

1. In vitro experiments have been conducted on the disappearance of potassium nitrate in ruminal ingesta from sheep on different diets. 2. Nitrate disappears more rapidly from ingesta of lucerne-fed sheep than from that of sheep on grass hay. 3. Nitrite is formed from the nitrate. It appears very soon after the addition of nitrate to the ingesta, reaches its maximum concentration at the moment of complete disappearance of the nitrate and subsequently itself disappears. Nitrite thus formed represents an intermediate stage in the conversion of nitrate to more fully reduced compounds. 4. The ratio nitrite disappearance time / nitrate disappearance time is constant for varying quantities of nitrate (Constant A). 5. The nitrite formed also disappears more rapidly from ingesta of lucerne-fed sheep than from that of sheep on grass hay. 6. The disappearance of nitrate from ingesta is represented graphically by plotting quantity of nitrate against time of disappearance. The resulting curve is a half parabola, with values varying for different ingesta. Daily variation for ingesta can be plotted from a series of such curves. 7. Nitrate disappearance rate can be used as an additional measure of ruminal activity. 8. The addition of glucose shortens the time of nitrate disappearance; the maximum effect for a fixed quantity of nitrate is produced by as little as 15 to 30 mg. of glucose per 20 c.c. of ingesta. 9. The "nitrate disappearance curve" is shifted in position, but remains unaltered in relative proportions, by the addition of a fixed quantity of glucose to the tube in each reading. The percentage reduction of time of disappearance of different quantities of nitrate due to a fixed quantity of glucose is a constant (Constant B). 10. The time of disappearance of nitrite formed from the nitrate is similarly affected by the presence of glucose. The percentage reduction of nitrite disappearance time due to a fixed quantity of glucose is also constant (Constant C). 11. "Nitrite persistence" is defined as the interval of time between the disappearance of nitrate and of nitrite. The percentage reduction of nitrite persistence due to a fixed quantity of glucose constitutes a fourth constant (Constant D). 12. An in vivo experiment confirmed the in vitro findings on the effects of nitrate, supplied either alone or in conjunction with sugar, on the ruminal ingesta of sheep. It demonstrated clearly the effect of diet and of sugar on nitrate persistence and therefore on nitrite poisoning. 13. Further work on this subject, both from the toxicological and the nutritional aspects, is in progress.The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format