976 resultados para Arctocephalus gazella, stomach content
Resumo:
This paper challenges the Kripkean interpretation of a posteriori necessities. It will be demonstrated, by an analysis of classic examples, that the modal content of supposed a posteriori necessities is more complicated than the Kripkean line suggests. We will see that further research is needed concerning the a priori principles underlying all a posteriori necessities. In the course of this analysis it will emerge that the modal content of a posteriori necessities can be best described in terms of a Finean conception of modality – by giving essences priority over modality. The upshot of this is that we might be able to establish the necessity of certain supposed a posteriori necessities by a priori means.
Resumo:
Powders are essential materials in the pharmaceutical industry, being involved in majority of all drug manufacturing. Powder flow and particle size are central particle properties addressed by means of particle engineering. The aim of the thesis was to gain knowledge on powder processing with restricted liquid addition, with a primary focus on particle coating and early granule growth. Furthermore, characterisation of this kind of processes was performed. A thin coating layer of hydroxypropyl methylcellulose was applied on individual particles of ibuprofen in a fluidised bed top-spray process. The polymeric coating improved the flow properties of the powder. The improvement was strongly related to relative humidity, which can be seen as an indicator of a change in surface hydrophilicity caused by the coating. The ibuprofen used in the present study had a d50 of 40 μm and thus belongs to the Geldart group C powders, which can be considered as challenging materials in top-spray coating processes. Ibuprofen was similarly coated using a novel ultrasound-assisted coating method. The results were in line with those obtained from powders coated in the fluidised bed process mentioned above. It was found that the ultrasound-assisted method was capable of coating single particles with a simple and robust setup. Granule growth in a fluidised bed process was inhibited by feeding the liquid in pulses. The results showed that the length of the pulsing cycles is of importance, and can be used to adjust granule growth. Moreover, pulsed liquid feed was found to be of greater significance to granule growth in high inlet air relative humidity. Liquid feed pulsing can thus be used as a tool in particle size targeting in fluidised bed processes and in compensating for changes in relative humidity of the inlet air. The nozzle function of a two-fluid external mixing pneumatic nozzle, typical for small scale pharmaceutical fluidised bed processes, was studied in situ in an ongoing fluidised bed process with particle tracking velocimetry. It was found that the liquid droplets undergo coalescence as they proceed away from the nozzle head. The coalescence was expected to increase droplet speed, which was confirmed in the study. The spray turbulence was studied, and the results showed turbulence caused by the event of atomisation and by the oppositely directed fluidising air. It was concluded that particle tracking velocimetry is a suitable tool for in situ spray characterisation. The light transmission through dense particulate systems was found to carry information on particle size and packing density as expected based on the theory of light scattering by solids. It was possible to differentiate binary blends consisting of components with differences in optical properties. Light transmission showed potential as a rapid, simple and inexpensive tool in characterisation of particulate systems giving information on changes in particle systems, which could be utilised in basic process diagnostics.
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The random direction short Glass Fiber Reinforced Plastics (GFRP) have been prepared by two compression moulding processes, namely the Preform and Sheet Moulding Compound (SMC) processes. Cutting force analysis and surface characterization are conducted on the random direction short GFRPs with varying fiber contents (25 similar to 40%). Edge trimming experiments are preformed using carbide inserts with varing the depth of cut and cutting speed. Machining characteristics of the Preform and SMC processed random direction short GFRPs are evaluated in terms of cutting forces, surface quality, and tool wear. It is found that composite primary processing and fiber contents are major contributing factors influencing the cutting force magnitudes and surface textures. The SMC composites show better surface finish over the Preform composites due to less delamination and fiber pullouts. Moreover, matrix damage and fiber protrusions at the machined edge are reduced by increasing fiber content in the random direction short GFRP composites.
Resumo:
Low-humidity monoclinic lysozyme, resulting from a water-mediated transformation, has one of the lowest solvent contents (22% by volume) observed in a protein crystal. Its structure has been solved by the molecular replacement method and refined to an R value of 0.175 for 7684 observed reflections in the 10–1.75 Å resolution shell. 90% of the solvent in the well ordered crystals could be located. Favourable sites of hydration on the protein surface include side chains with multiple hydrogen-bonding centres, and regions between short hydrophilic side chains and the main-chain CO or NH groups of the same or nearby residues. Major secondary structural features are not disrupted by hydration. However, the free CO groups at the C terminii and, to a lesser extent, the NH groups at the N terminii of helices provide favourable sites for water interactions, as do reverse turns and regions which connect β-structure and helices. The hydration shell consists of discontinuous networks of water molecules, the maximum number of molecules in a network being ten. The substrate-binding cleft is heavily hydrated, as is the main loop region which is stabilized by water interactions. The protein molecules are close packed in the crystals with a molecular coordination number of 14. Arginyl residues are extensively involved in intermolecular hydrogen bonds and water bridges. The water molecules in the crystal are organized into discrete clusters. A distinctive feature of the clusters is the frequent occurrence of three-membered rings. The protein molecules undergo substantial rearrangement during the transformation from the native to the low-humidity form. The main-chain conformations in the two forms are nearly the same, but differences exist in the side-chain conformation. The differences are particularly pronounced in relation to Trp 62 and Trp 63. The shift in Trp 62 is especially interesting as it is also known to move during inhibitor binding.
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The hot deformation behavior of α brass with varying zinc contents in the range 3%–30% was characterized using hot compression testing in the temperature range 600–900 °C and strain rate range 0.001–100 s−1. On the basis of the flow stress data, processing maps showing the variation of the efficiency of power dissipation (given by Image where m is the strain rate sensitivity) with temperature and strain rate were obtained. α brass exhibits a domain of dynamic recrystallization (DRX) at temperatures greater than 0.85Tm and at strain rates lower than 1 s−1. The maximum efficiency of power dissipation increases with increasing zinc content and is in the range 33%–53%. The DRX domain shifts to lower strain rates for higher zinc contents and the strain rate for peak efficiency is in the range 0.0001–0.05 s−1. The results indicate that the DRX in α brass is controlled by the rate of interface formation (nucleation) which depends on the diffusion-controlled process of thermal recovery by climb.
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Mining and blending operations in the high grade iron ore deposit under study are performed to optimize recovery with minimal alumina content while maintaining required levels of other chemical component and a proper mix of ore types. In the present work the regionalisation of alumina in the ores has been studied independently and its effects on global and local recoverable tonnage as well as on alternatives of mining operations have been evaluated. The global tonnage recovery curves for blocks (20m x 20m x 12m) obtained by simulation closely approximated the curves obtained theoretically using a change of support under the discretised gaussian model. Variations in block size up to 80m x 20m x 12m did not affect the recovery as the horizontal dimensions of the blocks are small in relation to the range of the variogram. A comparison of the local tonnage recovery curves obtained through multiple conditional simulations made with that obtained by the method of uniform conditioning of block grades on an estimate of panel 100m x 100m x 12m panel grade reveals comparable results only in panels which have been well conditioned and possesing an ensemble simulation mean close to the ordinary kriged value for the panel. Study of simple alternative sequence of mining on the conditionally simulated deposit shows that concentration of mining operations simultaneously on a single bench enhances the fluctuation in alumina values of ore mined.
Resumo:
LaMnO3+? samples with Mn4+ content up to 50% have been prepared by different methods. The structure of LaMnO3+? changes from orthorhombic to cubic (via rhombohedral) with increase in the Mn4+ content. LaMnO3+? samples containing greater than 20% Mn4+ are ferromagnetic and show resistivity maxima at a temperature Tt which is close to the ferromagnetic Curie temperature. The resistivity maximum is due to the occurrence of a metal-insulator transition. In samples heated to the same temperature, the value of Tt increases with % Mn4+. For a given sample, Tt increases with the temperature of heat treatment due to the increase in particle size. The onset of ferromagnetism in LaMnO3+? accompanied by an insulator-metal transition is similar to that found in La1-xCaxMnO3 and La1-xSrxCoO3.
Resumo:
The EU Directive harmonising copyright, Directive 2001/29/EC, has been implemented in all META-NORD countries. The licensing schemas of open content/open source and META-SHARE as well as CLARIN are discussed shortly. The status of the licensing of tools and resources available at the consortium partners are outlined. The aim of the article is to compare a set of open content and open source license and provide some guidance on the optimal use of licenses provided by META-NET and CLARIN for licensing the tools and resources for the benefit of the language technology community.
Resumo:
Studies on the low-humidity (88%) forms of tetragonal and monoclinic lysozyme, resulting from water-mediated transformations, have provided a wealth of information on the variability in protein hydration, its structural consequences and the water structure associated with proteins, in addition to facilitating the delineation of the rigid and the flexible regions in the protein molecule and the invariant features in its hydration shell. Surprisingly, monoclinic lysozyme continues to diffract even when the environmental humidity is drastically reduced, thus permitting the structural study of the enzyme at different levels of hydration. As part of a study in this direction, three very low humidity forms, two of them occuring at a nominal relative humidity of 38% and the other at 5% relative humidity, have been characterized. These have unprecedented low solvent contents of 16.9, 17.6 and 9.4%, respectively, as determined by the Matthews method.
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Abundant quantities of fly ash have been produced by thermal power plants situated ail over the world. Many applications of fly ash depend upon its pozzolanic reactivity. This reactivity depends upon many factors, including lime content. Many fly ashes show marked improvement with the addition of lime. However, for every fly ash, there is an optimum lime content for its maximum reactivity. There is no well-established simple test to determine the optimum lime content. In this paper an attempt is made to use a simple physical and physico chemical test to determine the optimum lime content. The principle behind the use of a pH test, liquid limit test, and free swell index test to determine the optimum lime content has been explained. All the methods predict nearly the same optimum lime content and correlate well with that determined by the strength test.
Resumo:
Magnetoresistance (MR) in bulk samples of LaMnO3 has been investigated by varying the Mn4+ content from 10 to 33 per cent by chemical means, without aliovalent doping. With the increase in Mn4+ content, the structure of LaMnO3 changes first from orthorhombic to rhombohedral and then to cubic and the material becomes increasingly ferromagnetic, exhibiting a resistivity maximum akin to an insulator-metal transition at T-Peak, just below the ferromagnetic T-c. The magnitude of MR is highest in the cubic sample (with 33% Mn4+) around the T-Peak, and negligible in the non-magnetic orthorhombic sample (12% Mn4+).
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Total tRNAs isolated from chloroplasts and etioplasts of cucumber cotyledons were compared with respect to amino acid acceptance, isoacceptor distribution and extent of modification. Aminoacylation of the tRNAs with nine different amino acids studied indicated that the relative acceptor activities of chloroplast total tRNAs for four amino acids are significantly higher than etioplast total tRNAs. Two dimensional polyacrylamide gel electrophoresis (2D-PAGE) of chloroplast total tRNAs separated at least 32 spots, while approximately 41 spots were resolved from etioplast total tRNAs. Comparison of the reversed-phase chromatography (RPC-5) profiles of chloroplast and etioplast leucyl-, lysyl-, phenylalanyl-, and valyl-tRNA species showed no qualitative differences in the elution profiles. However, leucyl-, lysyl- and valyl-tRNA species showed quantitative differences in the relative amounts of the isoaccepting species present in chloroplasts and etioplasts. The analysis of modified nucleotides of total tRNAs from the two plastid types indicated that total tRNA from etioplasts was undermodified with respect to ribothymidine, isopentenyladenosine/hydroxy-isopentenyladenosine, 1-methylguanosine and 2-o-methylguanosine. This indicates that illumination may cause de novo synthesis of chloroplast tRNA-modifying enzymes encoded for by nuclear genes leading to the formation of highly modified tRNAs in chloroplasts. Based on these results, we speculate that the observed decrease in levels of aminoacylation, variations in the relative amounts of certain isoacceptors, and differences in the electrophoretic mobilities of some extra tRNA spots in the etioplast total tRNAs as compared to chloroplast total tRNAs could be due to some partially undermodified etioplast tRNAs. Taken together, the data suggested that the light-induced transformation of etioplasts into chloroplasts is accompanied by increases in the relative levels of some functional chloroplast tRNAs by post transcriptional nucleotide modifications.
Resumo:
Uroguanylin, guanylin, and lymphoguanylin are small peptides that activate renal and intestinal receptor guanylate cyclases (GC). They are structurally similar to bacterial heat-stable enterotoxins (ST) that cause secretory diarrhea. Uroguanylin, guanylin, and ST elicit natriuresis, kaliuresis, and diuresis by direct actions on kidney GC receptors. A 3,762-bp cDNA characterizing a uroguanylin/guanylin/ST receptor was isolated from opossum kidney (OK) cell RNA/cDNA. This kidney cDNA (OK-GC) encodes a mature protein containing 1,049 residues sharing 72.4�75.8% identity with rat, human, and porcine forms of intestinal GC-C receptors. COS or HEK-293 cells expressing OK-GC receptor protein were activated by uroguanylin, guanylin, or ST13 peptides. The 3.8-kb OK-GC mRNA transcript is most abundant in the kidney cortex and intestinal mucosa, with lower mRNA levels observed in urinary bladder, adrenal gland, and myocardium and with no detectable transcripts in skin or stomach mucosa. We propose that OK-GC receptor GC participates in a renal mechanism of action for uroguanylin and/or guanylin in the physiological regulation of urinary sodium, potassium, and water excretion. This renal tubular receptor GC may be a target for circulating uroguanylin in an endocrine link between the intestine and kidney and/or participate in an intrarenal paracrine mechanism for regulation of kidney function via the intracellular second messenger, cGMP.
Resumo:
We report the tuning of oxygen content of La0.5Ca0.5MnO3-y and its effect on electrical transport and magnetic properties. A small reduction of oxygen content leads to a decrease in sample resistivity, which is more dramatic at low temperatures. No significant change is seen to occur in the magnetic properties for this case. Further reduction in the oxygen content increases the resistivity remarkably, as compared to the as-prepared sample. The amplitude of the ferromagnetic (FM) transition at 225 K decreases, and the antiferromagnetic (AFM) transition at 130 K disappears. For samples with y=0.17, insulator-metal transition and paramagnetic-ferromagnetic transition occur around 167 K. The results are explained in terms of the effect of oxygen vacancies on the coexistence of the metallic FM phase and the insulating charge ordered AFM phase.