986 resultados para particle number


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The application of variable-number tandem repeats (VNTR) genotyping of Mycobacterium avium subsp. paratuberculosis isolates to assist in investigating incidents of bovine Johne’s disease in a low-prevalence region of Australia is described in the current study. Isolates from a response to detection of bovine Johne’s disease in Queensland were compared with strains from national and international sources. The tandem application of mycobacterial interspersed repetitive unit (MIRU) and multilocus short sequence repeats (MLSSR) genotyping identified 2 strains, 1 that infected cattle on multiple properties with trace-forward histories from a common infected property, and 1 genotypically different strain recovered from a single property. The former strain showed an identical genotype to an isolate from India. Neither strain showed a genotypic link to regions of Australia with a higher prevalence of the disease. Genotyping has indicated incursions from 2 independent sources. This intelligence has informed investigations into potential routes of entry and the soundness of ongoing control measures, and supported strategy and policy decisions regarding management of Mycobacterium avium subsp. paratuberculosis incursions for Queensland.

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tRNA isolated from escherichia-coli grown in a medium containing [75Se] sodium selenosulfate was converted to nucleosides and analysed for selenonucleosides on a phosphocellulose column. Upon chromatography of the nucleosides on phosphocellulose column, the radioactivity resolved into three peaks. The first peak consisted of free selenium and traces of undigested nucleotides. The second peak was identified as 4-selenouridine by co-chromatographing with an authentic sample of 4-selenouridine. The identity of the third peak was not established. The second and third peaks represented 93% and 7% of the selenium present in nucleosides respectively.

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The text is divided into three parts; Properties, Application and Safety of Ammonium Nitrate (AN) based fertilisers. In Properties, the structures and phase transitions of ammonium and potassium nitrate are reviewed. The consequences of phase transitions affect the proper use of fertilisers. Therefore the products must be stabilised against the volume changes and consequent loss of bulk density and hardness, formation of dust and finally caking of fertilisers. The effect of different stabilisers is discussed. Magnesium nitrate, ammonium sulphate and potassium nitrate are presented as a good compromise. In the Application part, the solid solutions in the systems (K+,NH4+)NO3- and (NH4+,K+)(Cl-,NO3-) are presented based on studies made with DSC and XRD. As there are clear limits for solute content in the solvent lattice, a number of disproportionation transitions exist in these process phases, e.g., N3 (solid solution isomorphous to NH4NO3-III) disproportionates to phases K3 (solid solution isomorphous to KNO3-III) and K2 (solid solution isomorphous to KNO3-II). In the crystallisation experiments, the formation of K3 depends upon temperature and the ratio K/(K+NH4). The formation of phases K3, N3, and K2 was modelled as a function of temperature and the mole ratios. In introducing chlorides, two distinct maxima for K3 were found. Confirmed with commercial potash samples, the variables affecting the reaction of potassium chloride with AN are the particle size, time, temperature, moisture content and amount of organic coating. The phase diagrams obtained by crystallisation studies were compared with a number of commercial fertilisers and, with regard to phase composition, the temperature and moisture content are critical when the formation and stability of solid solutions are considered. The temperature where the AN-based fertiliser is solidified affects the amount of compounds crystallised at that point. In addition, the temperature where the final moisture is evaporated affects the amount and type of solid solution formed at this temperature. The amount of remaining moisture affects the stability of the K3 phase. The K3 phase is dissolved by the moisture and recrystallised into the quantities of K3, which is stable at the temperature where the sample is kept. The remaining moisture should not be free; it should be bound as water in the final product. The temperatures during storage also affect the quantity of K3 phase. As presented in the figures, K3 phase is not stable at temperatu¬res below 30 °C. If the temperature is about 40 °C, the K3 phase can be formed due to the remaining moisture. In the Safety part, self-sustaining decomposition (SSD), oxidising and energetic properties of fertilisers are discussed. Based on the consequence analysis of SSD, early detection of decomposition in warehouses and proper temperature control in the manufacturing process is important. SSD and oxidising properties were found in compositions where K3 exists. It is assumed that potassium nitrate forms a solid matrix in which AN can decompose. The oxidising properties can be affected by the form of the product. Granular products are inherently less oxidising. Finally energetic properties are reviewed. The composition of the fertiliser has an importance based on theoretical calculations supported by experimental studies. Materials such as carbonates and sulphates act as diluents. An excess of ammonium ions acts as a fuel although this is debatable. Based on the experimental work, the physical properties have a major importance over the composition. A high bulk density is of key importance for detonation resistance.

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tRNA isolated from . grown in a medium containing [75Se] sodium selenosulfate was converted to nucleosides and analysed for selenonucleosides on a phosphocellulose column. Upon chromatography of the nucleosides on phosphocellulose column, the radioactivity resolved into three peaks. The first peak consisted of free selenium and traces of undigested nucleotides. The second peak was identified as 4-selenouridine by co-chromatographing with an authentic sample of 4-selenouridine. The identity of the third peak was not established. The second and third peaks represented 93% and 7% of the selenium present in nucleosides respectively.

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We use the Lippman-Schwinger scattering theory to study nonequilibrium electron transport through an interacting open quantum dot. The two-particle current is evaluated exactly while we use perturbation theory to calculate the current when the leads are Fermi liquids at different chemical potentials. We find an interesting two-particle resonance induced by the interaction and obtain criteria to observe it when a small bias is applied across the dot. Finally, for a system without spatial inversion symmetry, we find that the two-particle current is quite different depending on whether the electrons are incident from the left or the right lead.

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Under lubricated conditions, Al-graphite particle composite is a good antiseizure bearing and antifriction material possessing properties which inhibit excessive temperature rise in bearings. The present study characterizes the dry wear properties of the composite. The dry wear characteristics of the Al-(2.7%–5.7% graphite particle) (50–200μm) composite were found to deteriorate with the addition of graphite, load and sliding distance. Both micro structural and microhardness studies of the worn subsurfaces and analysis of wear debris show that the reductions in strength and ductility of the composite due to graphite addition are the most likely causes of deterioration in the wear properties of the composite.

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A direct method of preparing cast aluminium alloy-graphite particle composites using uncoated graphite particles is reported. The method consists of introducing and dispersing uncoated but suitably pretreated graphite particles in aluminium alloy melts, and casting the resulting composite melts in suitable permanent moulds. The optical pretreatment required for the dispersion of the uncoated graphite particles in aluminium alloy melts consists of heating the graphite particles to 400° C in air for 1 h just prior to their dispersion in the melts. The effects of alloying elements such as Si, Cu and Mg on the dispersability of pretreated graphite in molten aluminium have also been reported. It was found that additions of about 0.5% Mg or 5% Si significantly improve the dispersability of graphite particles in aluminium alloy melts as indicated by the high recoveries of graphite in the castings of these composites. It was also possible to disperse upto 3% graphite in LM 13 alloy melts and retain the graphite particles in a well distributed fashion in the castings using the pre-heat-treated graphite particles. The observations in this study have been related to the information presently available on wetting between graphite and molten aluminium in the presence of different elements and our own thermogravimetric analysis studies on graphite particles. Physical and mechanical properties of LM 13-3% graphite composite made using pre-heat-treated graphite powder, were found to be adequate for many applications, including pistons which have been successfully used in internal combustion engines.

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An experimental study is presented to show the effect of the cowl location and shape on the shock interaction phenomena in the inlet region for a 2D, planar scramjet inlet model. Investigations include schlieren visualization around the cowl region and heat transfer rate measurement inside the inlet chamber.Both regular and Mach reflections are observed when the forebody ramp shock reflects from the cowl plate. Mach stem heights of 3.3 mm and 4.1 mm are measured in 18.5 mm and 22.7 mm high inlet chambers respecively. Increased heat transfer rate is measured at the same location of chamber for cowls of longer lenghs is indicating additional mass flow recovery by the inlet.

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Considers the magnetic response of a charged Brownian particle undergoing a stochastic birth-death process. The latter simulates the electron-hole pair production and recombination in semiconductors. The authors obtain non-zero, orbital diamagnetism which can be large without violating the Van Leeuwen theorem (1921).

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We perceive the epistemological boundaries of Critical Indigenous Studies as marked by analyses of contemporary colonising power in its multiple forms in different contexts. This first issue brings together a diverse group of international Indigenous scholars who are politically and intellectually engaged in theorising from their respective standpoints as well as spatial and geographic locations. As such these essays enable dialogue across and within different colonial power contexts addressing epistemological ethical and methodological concerns within the broad field of Indigenous studies. In each essay a connecting theme is the need for intercultural and comparative work and to import Indigenous agency in the writing of history...

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Over the past two decades neo liberalism has shaped global economic activity. The international reach of the current economic crisis propelled by the subprime mortgage meltdown in the United States has affected Indigenous communities in different ways to those whose investments were depleted by the Wall Street activities of an unregulated corporate and banking sector. Throughout this roller coaster economic ride the low socio-economic position of Indigenous peoples continued in Canada, the United States of America, New Zealand, Hawaii and Australia. The logic, or illogic of capital, failed to extend the boom of the economic upturn to Indigenous peoples, but is poised to extend the repercussions of the current downturn deep into Indigenous lives. The consistency of the Indigenous socio-economic position across these countries, even where treaties exist, indicates that the phenomenon is based on a shared Indigenous reality. In this special edition, the commonality in the way in which Indigenous people are engaged in and positioned by market forces and regulation by their respective nation states is proposed as one of the foundation plates of that Indigenous positioning...

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This edition of the International Critical Indigenous Studies Journal, our second for 2009 takes alternative understandings as its theme. All four articles in this edition attend to citizenship and Indigenous sovereignty though in different ways...

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The articles in this edition of the International Journal of Critical Indigenous Studies engage collectively with how different epistemologies and cultural values inform power relations in different locations, situations and contemporary contexts. As a group, these articles demonstrate, over varying facets, how meaning, communicative intent and interpretive effect are constitutive of power relations between Indigenous people and non Indigenous people. Jackie Grey discusses the labour of belonging as played out in a dispute over Indigenous fishing rights in a small New England town of Aquinnah, located on Noepe Island the traditional lands of the Wampanoag in the United States of America. She reveals the ways in which the jurisdiction of non Indigenous belonging operates discursively and materially to preclude Indigenous rights and self determination. Grey's analysis highlights the incommensurability of Indigenous and non Indigenous belonging that are played out in power relations born of colonisation.

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In this of the International Journal of Critical Indigenous Studies, the articles reveal how competing economies of knowledge, capital and values are operationalised through colonising power within inter-subjective relations. Writing in the Australian context, Greg Blyton demonstrates how tobacco was used by colonists as a means of control and exchange in their relations with Indigenous people. He focuses on the Hunter region of New South Wales, Australia, in the early to mid-nineteenth century to reveal how colonists exchanged tobacco for food, safe passage and Indigenous services. Blyton suggests that these colonial practices enabled tobacco addiction to spread throughout the region, passing from one generation of Indigenous people to another. He asks us to consider the link between the colonial generation of Indigenous tobacco consumption and addiction, and Indigenous mortality rates today whereby twenty percent of deaths are attributed to smoking.

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This special edition of the International Journal of Critical Indigenous Studies highlights the work of emerging scholars in the field of Indigenous Studies. The five featured authors were all finalists for the prize awarded by the Native American and Indigenous Studies Association (NAISA) to the best post-graduate student paper at the NAISA meeting held in 2010 in Tucson, Arizona. While the breadth of scholarship encompassed by the term ‘Indigenous Studies’ and the global representation of Indigenous peoples at NAISA mean that the topics and approaches vary widely, a common thematic of fraught post-colonial relations can be discerned within all five articles.