978 resultados para Composition assistée par ordinateur


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Determination of the protein content and lysine levels of a number of nonhybrid varieties of grain sorghum indicates large variations in the protein content. Statistical analysis of data on amounts of lysine shows that a negative correlation exists between per cent lysine in the protein and per cent protein in the seed. The proportion of various protein fractions in endosperm of five varieties of grain sorghum of both low- and high-protein type has been determined. Results show that prolamine and glutelin are the principal protein fractions, and increased protein levels in sorghum varieties are correlated with an increase mainly in the prolamine fraction. Nine high- and low-protein varieties of grain sorghum have been analyzed for their amino acid composition by ion exchange procedures. One of the high-protein genetic varieties of sorghum has a high concentration of lysine in the seed. Amino acid composition of the protein fractions of two varieties is also reported. These data permit an evaluation of the nutritional quality of sorghum protein and factors that influence the quality of the protein.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Solutions of potassium chloride (pH-buffered and 1-molat) equilibrated at 350°C with pyrrhotite, pyrite, and magnetite contained approximately 1 millimole of reduced sulfur and less than 0.1 millimole of oxidized sulfur per kilogram. Similar solutions equilibrated with pyrite, magnetite, and hematite contained approximately 1 millimole of reduced sulfur, but 3 to 6 millimoles of oxidized sulfur per kilogram. Both types of solutions contained less than 0.1 millimole of iron per kilogram at pH ≥ 6 and approximately 100 millimoles per kilogram at pH 2.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The constituents of silkworm fat were studied in detail. An unsaturated fat with a high concentration of phospholipid was generally observed. Its iodine value increased during metamorphosis. The free fatty acid concentration likewise increased from the spinning larvae to the moth stage. Analyses of silkworm organs revealed that the fat body had the most fat and the least free fatty acids, whereas haemolymph contained the least fat. Silk glands contained the maximum phospholipid percentage. Stearic acid predominated in those tissues that had a high percentage of phospholipid. Stearic acid was the predominant saturated fatty acid in both the phospholipids and lecithin, and it accounted for 35–50 per cent of the free fatty acids of all the tissues. Q10 was the ubiquinone present; also found were ubichromenol and tocopherol. Results show that silkworm sterol may be cholesterol. Intestines contained the maximum quantities of sterol, ubiquinone, ubichromenol, and tocopherol. The composition of silkworm phospholipids varies considerably from those of other insects, but lecithin is comparable in its composition with lecithins of other animals. The phospholipids had with them a highly complexed protein along with a polysaccharide. In experiments with snake venoms unsaturated fatty acids were found to be predominantly released from silkworm lecithin.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Words as Events introduces the tradition of short, communicative rhyming couplets, the mantinádes, which are still sung and recited in a variety of performance situations on the island of Crete. The local focus on communicative economy and artistry is further examined in an in-depth analysis of the processes and ideals of composition. Short genres of oral poetry have been widely neglected in folklore research; however, their demand for structural and semantic coherence as well as their dialogic nature appeals to very different human needs from those of the longer poems. In contemporary Crete, poems also appear in written contexts, they are submitted to modern mass media, and people widely exchange them as text messages. By striving to understand the tradition during a period of change, this study analyzes the larger principles that ground the communication, self-expression and creativity in the genre. The aim of this research is thus twofold: to present this specific register of dialogic oral poetry as well as to create a theoretical approach sensitive to the creativity of such short registers. The study is based on long-term ethnographic fieldwork conducted in Crete between the years 1997 2009. An important aspect of the methodology was to create long-term ties with a number of key-informants who composed mantinádes. The interdisciplinary theoretical and methodological basis for this analysis is in the contemporary Finnish and international research on oral poetry and on anthropological research on communicative speech genres. These theoretical insights are extended by addressing questions of spontaneity and individual agency. Since mantinádes are at the same time a model for composition and a reserve of poems in fixed form, the aesthetics and objectives of performance and composition are also plural. In a traditional singing event, the basic motivation for the singers is to provide a meaningful contribution to a selected theme, which is the shared topic of the poetic dialogue. Consequently, similar topics giving rise to poetic associations can be encountered during various moments of everyday life: the dialogic nature is embodied in the tradition to such degree that it also arises in the performances and composition of single poems and outside of any institutionalized performance arenas. Therefore, as this study discusses in detail, even the apparently non-contextualized poems recited between locals or occurring in the contemporary mass media arenas, are understood and evaluated as utterances that provide an individual perspective within a certain dialogue.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Superconductivity in cuprates of the general formula TlCa1-xLnxSr2Cu2O7+ delta has been investigated as a function of Ln and x. Compositions with 0.250.25. Thus, these cuprates exhibit a composition-dependent electron- or hole-superconductivity. In the normal state, most of the members of the series traverse compositionally determined metal-insulator transitions. High-energy spectroscopies show the presence of Cu in the 1+ and 2+ states. The Raman frequency around 525 cm-1 characteristic of the Tl-O2-Cu linkage is sensitive to both Ln and x, indicating a possible involvement in the mechanism of superconductivity.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Détermination de l'activité du calcium par la méthode d'effusion de Knudsen. Calcul, à partir de la distribution mesurée pour l'aluminium entre l'alliage et du fer pur, de l'activité de l'aluminium dans des alliages riches en calcium. Détermination en combinant les deux méthodes, des activités des deux composants et de l'énergie de Gibbs de mélange pour tout le domaine de composition. Calcul et analyse du facteur de structure concentration-concentration

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Bulk As-Te-Tl glasses belonging to the As30Te70-xTlx (4 <= x <= 22) and As40Te60-xTlx (5 <= x <= 20) composition tie lines are studied for their I-V characteristics. Unlike other As-Te-III glasses such as As-Te-Al and As-Te-In, which exhibit threshold behavior, the present samples show memory switching. The composition dependence of switching voltages (V-t) of As-Te-Tl glasses is also different from that of As-Te-Al and As-Te-In glasses, and it is found that V-t decreases with the addition of Tl. Both the type of switching exhibited by As-Te-Tl glasses and the composition dependence of V-t, seems to be intimately connected with the nature of bonding of Tl atoms and the resultant structural network. Furthermore, the temperature and thickness dependence of switching voltages of As-Te-Tl glasses suggest an electro thermal mechanism for switching in these samples.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The electrical resistivity of bulk GexTe100-x glasses has been measured as a function of temperature and pressure. Under high pressure, all the glasses were found to undergo sharp discontinuous transitions from glassy semiconductors to crystalline metal. Several of the observed properties such as the transition pressure, conductivity activation energy and pre-exponential factor, exhibit anomalous trends at a composition x = 20. These results suggest that the x = 20 composition in the Ge-Te system should possess salient structural features. A model based on the unusual stability of structural units is proposed for explaining the anomaly at 20 at.% Ge concentration.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The Earth s climate is a highly dynamic and complex system in which atmospheric aerosols have been increasingly recognized to play a key role. Aerosol particles affect the climate through a multitude of processes, directly by absorbing and reflecting radiation and indirectly by changing the properties of clouds. Because of the complexity, quantification of the effects of aerosols continues to be a highly uncertain science. Better understanding of the effects of aerosols requires more information on aerosol chemistry. Before the determination of aerosol chemical composition by the various available analytical techniques, aerosol particles must be reliably sampled and prepared. Indeed, sampling is one of the most challenging steps in aerosol studies, since all available sampling techniques harbor drawbacks. In this study, novel methodologies were developed for sampling and determination of the chemical composition of atmospheric aerosols. In the particle-into-liquid sampler (PILS), aerosol particles grow in saturated water vapor with further impaction and dissolution in liquid water. Once in water, the aerosol sample can then be transported and analyzed by various off-line or on-line techniques. In this study, PILS was modified and the sampling procedure was optimized to obtain less altered aerosol samples with good time resolution. A combination of denuders with different coatings was tested to adsorb gas phase compounds before PILS. Mixtures of water with alcohols were introduced to increase the solubility of aerosols. Minimum sampling time required was determined by collecting samples off-line every hour and proceeding with liquid-liquid extraction (LLE) and analysis by gas chromatography-mass spectrometry (GC-MS). The laboriousness of LLE followed by GC-MS analysis next prompted an evaluation of solid-phase extraction (SPE) for the extraction of aldehydes and acids in aerosol samples. These two compound groups are thought to be key for aerosol growth. Octadecylsilica, hydrophilic-lipophilic balance (HLB), and mixed phase anion exchange (MAX) were tested as extraction materials. MAX proved to be efficient for acids, but no tested material offered sufficient adsorption for aldehydes. Thus, PILS samples were extracted only with MAX to guarantee good results for organic acids determined by liquid chromatography-mass spectrometry (HPLC-MS). On-line coupling of SPE with HPLC-MS is relatively easy, and here on-line coupling of PILS with HPLC-MS through the SPE trap produced some interesting data on relevant acids in atmospheric aerosol samples. A completely different approach to aerosol sampling, namely, differential mobility analyzer (DMA)-assisted filter sampling, was employed in this study to provide information about the size dependent chemical composition of aerosols and understanding of the processes driving aerosol growth from nano-size clusters to climatically relevant particles (>40 nm). The DMA was set to sample particles with diameters of 50, 40, and 30 nm and aerosols were collected on teflon or quartz fiber filters. To clarify the gas-phase contribution, zero gas-phase samples were collected by switching off the DMA every other 15 minutes. Gas-phase compounds were adsorbed equally well on both types of filter, and were found to contribute significantly to the total compound mass. Gas-phase adsorption is especially significant during the collection of nanometer-size aerosols and needs always to be taken into account. Other aims of this study were to determine the oxidation products of β-caryophyllene (the major sesquiterpene in boreal forest) in aerosol particles. Since reference compounds are needed for verification of the accuracy of analytical measurements, three oxidation products of β-caryophyllene were synthesized: β-caryophyllene aldehyde, β-nocaryophyllene aldehyde, and β-caryophyllinic acid. All three were identified for the first time in ambient aerosol samples, at relatively high concentrations, and their contribution to the aerosol mass (and probably growth) was concluded to be significant. Methodological and instrumental developments presented in this work enable fuller understanding of the processes behind biogenic aerosol formation and provide new tools for more precise determination of biosphere-atmosphere interactions.