Design considerations for the airframe-integrated scramjet

Research programs at the NASA Langley Research Center on the development of airframe-integrated scramjet concepts (supersonic combustion ramjet) are reviewed briefly. The design and performance of a specific scramjet configuration are examined analytically by use of recently developed and substantiated techniques on boundary-layer development, heat transfer, fuel-air mixing, heat-release rates, and engine-cycle analysis. These studies indicate that the fixed-geometry scramjet module will provide practical levels of thrust performance with low cooling requirements. Areas which need particular emphasis in further development work are the combustor design for low speeds and the integrated nozzle design

Miners' nystagmus

1. Miners' nystagmus is an occupational disease of the nervous system, occuring in two forms, confined to workers in coal mines. The chief physical sign is a rotatory oscillation of the eyeballs giving rise to apparent movement of objects as its prime symptom.2. The disease, generally of gradual onset, though acute cases are seen, especially in the young, attacks men of all ages, but is most commonly seen in middle life.3. Deficient light is the chief etiological factor, other factors such as method of work, accidents, errors of refraction, alcoholism and general diseases, are of secondary importance only.4. As to prognosis, there is no truth in the statement that miners' nystagmus causes permanent damage to the eye, or even blindness, if underground work is continued after the onset of symptoms.5. The disease may be said to be a benign one as it is pre -eminently curable.6. The ideal preventative measure would be to instal elec- tric lighting at the coal face but .o the men will not have elec- tricity either for lighting or for machinery in view of the prevalence of gas, the obligatory stone dusting and the adoption of white washing coupled with a change of lamps to the cap pattern, will, I believe, help, if not to wipe out nystagmus, at least to render it sufficiently mild so that incapacity resulting from it will be largely prevented

Rice World Market Prices

The marketing loan program associated with rice features benefits calculated using a USDA-announced World Market Price (WMP) rather than the posted county prices that are used for most other commodities. This results in reduced risk protection for producers relative to other crops, and greater difficulty in making optimal use of program benefits. This research investigates the rice WMP, identifying the relative importance of various foreign prices and other potential influencing factors. The results of this research have important implications for financial planning and optimal risk management strategies for rice producers.Agricultural and Food Policy,

Aggregate Milk Supply Response to the Milk Income Loss Contract Program

This research tests for changes in aggregate milk production due to the operation of the Milk Income Loss Contract (MILC) program since 2002. Aggregate production is decomposed into the size of the dairy herd and milk production per cow. We find no statistically significant response in either variable. This finding implies that the simultaneous operation of income and price support programs in the United States has not, thus far, proven self-defeating.dairy, income support, policy, price support, Agribusiness, Livestock Production/Industries,

Biosynthesis of the Pyrrolizidine Alkaloid Rosmarinine

The work presented in this thesis is divided into three sections: (a) Biosynthesis of rosmarinecine; (b) Synthesis of macro-cyclic pyrrolizidine diester analogues; and (c) Structural studies. (a) Biosynthesis of Rosmarinecine The biosynthesis of rosmarinecine, the base portion of the pyrrolizidine alkaloid rosmarinine (A), has been studied in Senecio pleistocephalus (family Compositae) plants. Samples of [1-13C]- and [2,3-13C2]putrescine dihydrochloride were incorporated with very high specific incorporations (up to 25% per unit) into rosmarinine. 13C N.m.r. spectroscopy established complete labelling patterns and showed that two molecules of putrescine were incorporated to about the same extent into rosmarinine. The incorporation of [1-amino-15N, 1-13C]- putrescine dihydrochloride into rosmarinine produced a labelling pattern which was indicative of the conversion of two putrescine molecules into a C4-N-C4 symmetrical intermediate. Intact incorporation of [1,9-13C2]- homospermidine trihydrochloride into rosmarinecine, was consistent with this intermediate being homospermidine. The stereochemistry of the enzymic processes in the pathway was investigated by feeding (R)-[1-2H]- and (S)-[1-2H] putrescine dihydrochloride to S. pleistocephalus. The labelling patterns obtained in rosmarinine, as determined by 2H n.m.r. spectroscopy, were consistent with the following. The oxidation of putrescine to 4-aminobutanal occurs with the loss of the pro-S hydrogen. The aldehyde and another molecule of putrescine condense to give the corresponding imine, which after reduction (on the C-si face) affords homospermidine. Two further oxidations each take place with loss of the pro-S hydrogens generating the dialdehyde, which after Mannich cyclisation produces 1B -formyl-8a-pyrrolizidine. Reduction to isoretronecanol proceeds by the delivery of a hydride equivalent on the C-re face of the carbonyl group. Feeding experiments with (R)-[2-2H]- and (S)-[2-2H]putrescine dihydrochloride established that the two hydroxylations in rosmarinecine occur with retention of configuration and that formation of the pyrrolizidine ring involves the stereospecific removal of the pro-R hydrogen on the carbon which becomes C-1 of rosmarinecine. The proposed product from the first oxidation of homospermidine, N-(4-aminobutyl)-1,2-didehydropyrrolidinium, was shown to be an intermediate in the biosynthetic pathways to several pyrrolizidine alkaloids, by 14C-labelling experiments and an intermediate trapping experiment. Platynecine was shown to be an efficient precursor for rosmarinecine biosynthesis using 3H-labelling experiments. Similarly, rosmarinecine was found to be an efficient precursor for rosmarinine biosynthesis. (b) Synthesis of Macrocyclic Pyrrolizidine Diester Analogues A number of optically active 12-membered macrocyclic dilactones containing (+)-6alpha-hydroxy-1alpha-hydroxymethyl-8beta-pyrrolizidine were prepared by lactonisation via the pyridine-2-thiolesters with different anhydrides. These are the first synthetic macrocyclic pyrrolizidine diester analogues which contain a saturated pyrrolizidine base. (c) Structural Studies The plant Lindelofia longiflora (family Boraginaceae) was shown, by spectroscopic studies, to contain one pyrrolizidine alkaloid, echinatine. Similarly, Cynoglossum macrostylum (family Boraginaceae) was found to contain two major alkaloidal components. Echinatine and heliosupine were identified in the ratio 3:1

CLXXXII.?Hyenanchin and other constituents of Hyenanche globosa

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