997 resultados para Nitrogen transformation


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The adsorption of carbon dioxide and nitrogen molecules on aluminum nitride (AlN) nanostructures has been explored using first-principle computational methods. Optimized configurations corresponding to physisorption and, subsequentially, chemisorption of CO2 are identified, in contrast to N2, for which only a physisorption structure is found. Transition-state searches imply a low energy barrier between the physisorption and chemisorption states for CO2 such that the latter is accessible and thermodynamically favored at room temperature. The effective binding energy of the optimized chemisorption structure is apparently larger than those for other CO2 adsorptive materials, suggesting the potential for application of aluminum nitride nanostructures for carbon dioxide capture and storage.

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XRD (X-ray diffraction), XRF (X-ray fluorescence), TG (thermogravimetry), FT-IES (Fourier transform infrared emission spectroscopy), FESEM (field emission scanning electron microscope), TEM (transmission electron microscope) and nitrogen–adsorption–desorption analysis were used to characterize the composition and thermal evolution of the structure of natural goethite. The in situ FT-IES demonstrated the start temperature (250 °C) of the transformation of natural goethite to hematite and the thermodynamic stability of protohematite between 250 and 600 °C. The heated products showed a topotactic relationship to the original mineral based on SEM analysis. Finally, the nitrogen–adsorption–desorption isotherm provided the variation of surface area and pore size distribution as a function of temperature. The surface area displayed a remarkable increase up to 350 °C, and then decreased above this temperature. The significant increase in surface area was attributed to the formation of regularly arranged slit-shaped micropores running parallel to elongated direction of hematite microcrystal. The main pore size varied from 0.99 nm to 3.5 nm when heating temperature increases from 300 to 400 °C. The hematite derived from heating goethite possesses high surface area and favors the possible application of hematite as an adsorbent as well as catalyst carrier.

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This PhD practice-led research inquiry sets out to examine and describe how the fluid interactions between memory and time can be rendered via the remediation of my painting and the construction of a digital image archive. My abstract digital art and handcrafted practice is informed by Deleuze and Guattari’s rhizomics of becoming. I aim to show that the technological mobility of my creative strategies produce new conditions of artistic possibility through the mobile principles of rhizomic interconnection, multiplicity and diversity. Subsequently through the ongoing modification of past painting I map how emergent forms and ideas open up new and incisive engagements with the experience of a ‘continual present’. The deployment of new media and cross media processes in my art also deterritorialises the modernist notion of painting as a static and two dimensional spatial object. Instead, it shows painting in a postmodern field of dynamic and transformative intermediality through digital formats of still and moving images that re-imagines the relationship between memory, time and creative practice.

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Nitrous oxide emissions from intensive, fertilised agricultural systems have been identified as significant contributors to both Australia's and the global greenhouse gas (GHG) budget. This is expected to increase as rates of agriculture intensification and land use change accelerate to support population growth and food production. Limited data exists on N2O trace gas fluxes from subtropical or tropical tree cropping soils critical for the development of effective mitigation strategies.This study aimed to quantify GHG emissions over two consecutive years (March 2007 to March 2009) from a 30 year (lychee) orchard in the humid subtropical region of Australia. GHG fluxes were measured using a combination of high temporal resolution automated sampling and manually sampled chambers. No fertiliser was added to the plots during the 2007 measurement season. A split application of nitrogen fertiliser (urea) was added at the rate of 265kgNha-1 during the autumn and spring of 2008. Emissions of N2O were influenced by rainfall events and seasonal temperatures during 2007 and the fertilisation events in 2008. Annual N2O emissions from the lychee canopy increased from 1.7kgN2O-Nha-1yr-1 for 2007, to 7.6kgN2O-Nha-1yr-1 following fertiliser application in 2008. This represented an emission factor of 1.56%, corrected for background emissions. The timing of the split application was found to be critical to N2O emissions, with over twice as much lost following an application in spring (2.44%) compared to autumn (EF: 1.10%). This research suggests that avoiding fertiliser application during the hot and moist spring/summer period can reduce N2O losses without compromising yields.

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Sandy soils have low nutrient holding capacity and high water conductivity. Consequently, nutrients applied as highly soluble chemical fertilisers are prone to leaching, particularly in heavily irrigated environments such as horticultural soils and golf courses. Amorphous derivatives of kaolin with high cation exchange capacity may be loaded with desired nutrients and applied as controlledrelease fertilisers. Kaolin is an abundant mineral, which can be converted to a meso-porous amorphous derivative (KAD) using facile chemical processes. KAD is currently being used to sequester ammonium from digester effluent in sewage treatment plants in a commercial environment. This material is also known in Australia by the trade name MesoLite. The ammonium-saturated form of KAD may be applied to soils as a nitrogen fertiliser. Up to 7% N can be loaded onto KAD by contacting it with high-ammonia concentration wastewater from sewerage treatment plants. This poster paper demonstrates plant uptake of nitrogen from KAD and compares its efficiency as a fertiliser with NH4SO4. Rye grass was grown in 1kg pots in a glass-house. Nitrogen was applied at a range of rates using NH4SO4 and two KAD materials carrying 7% and 3% nitrogen, respectively. All other nutrients were applied in adequate amounts. All treatments were replicated three times. Plants were harvested after four weeks. Dry mass and N concentrations were determined by standard methods. At all N application rates, ammonium-loaded KAD produced significantly higher plant mass than for NH4SO4. The lower fertiliser effectiveness of NH4SO4 is attributed to possible loss of some N through volatilisation. Of the two KAD types, the material with lower CEC value supported slightly higher plant yields. The KAD materials did not show any adverse effect on availability of trace elements, as evidenced by lack of deficiency symptoms and plant analyses. Clearly, nitrogen loaded on to KAD in the form of ammonium is likely to be protected from leaching, but is still available to plants. These data suggest that KAD-based fertilisers may be suitable substitutes for water soluble N, K and other cation fertilisers for leaching soils.

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Presently organisations engage in what is termed as Global Business Transformation Projects [GBTPs], for consolidating, innovating, transforming and restructuring their processes and business strategies while undergoing fundamental change. Culture plays an important role in global business transformation projects as these involve people of different cultural backgrounds and span across countries, industries and disciplinary boundaries. Nevertheless, there is scant empirical research on how culture is conceptualised beyond national and organisational cultures but also on how culture is to be taken into account and dealt with within global business transformation projects. This research is situated in a business context and discovers a theory that aids in describing and dealing with culture. It draws on the lived experiences of thirty-two senior management practitioners, reporting on more than sixty-one global business transformation projects in which they were actively involved. The research method used is a qualitative and interpretive one and applies a grounded theory approach, with rich data generated through interviews. In addition, vignettes were developed to illustrate the derived theoretical models. The findings from this study contribute to knowledge in multiple ways. First, it provides a holistic account of global business transformation projects that describe the construct of culture by the elements of culture types, cultural differences and cultural diversity. A typology of culture types has been developed which enlarges the view of culture beyond national and organisational culture including an industry culture, professional service firm culture and 'theme' culture. The amalgamation of the culture types instantiated in a global business transformation project compromises its project culture. Second, the empirically grounded process for managing culture in global business transformation projects integrates the stages of recognition, understanding and management as well as the enablement providing a roadmap for dealing with culture in global business transformation projects. Third, this study identified contextual variables to global business transformation projects, which provide the means of describing the environment global business transformation projects are situated, influence the construct of culture and inform the process for managing culture. Fourth, the contribution to the research method is the positioning of interview research as a strategy for data generation and the detailed documentation applying grounded theory to discover theory.

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Many aspects of China's academic publishing system differ from the systems found in liberal market based economies of the United States, Western Europe and Australia. A high level of government intervention in both the publishing industry and academia and the challenges associated with attempting to make a transition from a centrally controlled towards a more market based publishing industry are two notable differences; however, as in other countries, academic communities and publishers are being transformed by digital technologies. This research explores the complex yet dynamic digital transformation of academic publishing in China, with a specific focus of the open and networked initiatives inspired by Web 2.0 and social media. The thesis draws on two case studies: Science Paper Online, a government-operated online preprint platform and open access mandate; and New Science, a social reference management website operated by a group of young PhD students. Its analysis of the innovations, business models, operating strategies, influences, and difficulties faced by these two initiatives highlights important characteristics and trends in digital publishing experiments in China. The central argument of this thesis is that the open and collaborative possibilities of Web 2.0 inspired initiatives are emerging outside the established journal and monograph publishing system in China, introducing innovative and somewhat disruptive approaches to the certification, communication and commercial exploitation of knowledge. Moreover, emerging publishing models are enabling and encouraging a new system of practising and communicating science in China, putting into practice some elements of the Open Science ethos. There is evidence of both disruptive change to old publishing structures and the adaptive modification of emergent replacements in the Chinese practice. As such, the transformation from traditional to digital and interactive modes of publishing, involves both competition and convergence between new and old publishers, as well as dynamics of co-evolution involving new technologies, business models, social norms, and government reform agendas. One key concern driving this work is whether there are new opportunities and new models for academic publishing in the Web 2.0 age and social media environment, which might allow the basic functions of communication and certification to be achieved more effectively. This thesis enriches existing knowledge of open and networked transformations of scholarly publishing by adding a Chinese story. Although the development of open and networked publishing platforms in China remains in its infancy, the lessons provided by this research are relevant to practitioners and stakeholders interested in understanding the transformative dynamics of networked technologies for publishing and advocating open access in practice, not only in China, but also internationally.

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One set of public institutions that has seen growing discussion about the transformative impact of new media technologies has been universities. The higher education sector, historically one of the more venerable and stable areas of public life, is now the subject of almost continuous speculation about whether it can continue in its current form during the 21st century. Digital media technologies are often seen as being at the forefront of such changes. It has been widely noted that moves towards a knowledge economy generates ‘skills-biased technological change’, that places a premium upon higher education qualifications, and that this earnings gap remains despite the continuing increase in the number of university graduates. As the demand for higher education continues to grow worldwide, there are new discussions about whether technologically-mediated education through new forms such as Massively Open Online Courses (MOOCs) are broadening access to quality learning, or severing the vital connection between teacher and student seen as integral to the learning process. This paper critically appraises such debates in the context of early 21st century higher education. It will discuss ten drivers of change in higher education, many of which are related to themes discussed elsewhere in this book, such as the impact of social media, globalization, and a knowledge economy. It will also consider the issues raised in navigating such developments from the perspective of the ‘Five P’s’: practical issues; personal issues; pedagogical issues; policy issues; and philosophical issues. It also includes a critical evaluation of MOOCs from the point of view of their educational qualities. It will conclude with the observation that while universities will continue to play a significant – and perhaps growing – role in the economy, society and culture, the issues raised about what Clayton Christensen and Henry Eyring term the ‘disruptive university’ (Christensen and Eyring 2011) are nonetheless pressing ones, and that cost and policy pressures in particular are likely to generate significant institutional transformations in higher education worldwide.

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We demonstrate an unusual shape transformation of Ag nanospheres into {111}-oriented Au–Ag dendritic nanostructures by a galvanic replacement reaction in the ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]).

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The chemically reversible solid−solid phase transformation of a TCNQ-modified glassy carbon, indium tin oxide, or metal electrode into Co\[TCNQ]2(H2O)2 material in the presence of Co2+(aq) containing electrolytes has been induced and monitored electrochemically. Voltammetric data reveal that the TCNQ/Co\[TCNQ]2(H2O)2 interconversion process is independent of electrode material and identity of cobalt electrolyte anion. However, a marked dependence on electrolyte concentration, scan rate, and method of electrode modification (drop casting or mechanical attachment) is found. Cyclic voltammetric and double potential step chronoamperometric measurements confirm that formation of Co\[TCNQ]2(H2O)2 occurs through a rate-determining nucleation and growth process that initially involves incorporation of Co2+(aq) ions into the reduced TCNQ crystal lattice at the TCNQ|electrode|electrolyte interface. Similarly, the reverse (oxidation) process, which involves transformation of solid Co\[TCNQ]2(H2O)2 back to parent TCNQ crystals, also is controlled by nucleation−growth kinetics. The overall chemically reversible process that represents this transformation is described by the reaction:  2TCNQ0(s) + 2e- + Co2+(aq) + 2H2O \[Co(TCNQ)2(H2O)2](s). Ex situ SEM images illustrated that this reversible TCNQ/Co\[TCNQ]2(H2O)2 conversion process is accompanied by drastic size and morphology changes in the parent solid TCNQ. In addition, different sizes of needle-shaped nanorod/nanowire crystals of Co\[TCNQ]2(H2O)2 are formed depending on the method of surface immobilization.

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In situ atomic force microscopy (AFM) allows images from the upper face and sides of TCNQ crystals to be monitored during the course of the electrochemical solid–solid state conversion of 50 × 50 μm2 three-dimensional drop cast crystals of TCNQ to CuTCNQ or M[TCNQ]2(H2O)2 (M = Co, Ni). Ex situ images obtained by scanning electron microscopy (SEM) also allow the bottom face of the TCNQ crystals, in contact with the indium tin oxide or gold electrode surface and aqueous metal electrolyte solution, to be examined. Results show that by carefully controlling the reaction conditions, nearly mono-dispersed, rod-like phase I CuTCNQ or M[TCNQ]2(H2O)2 can be achieved on all faces. However, CuTCNQ has two different phases, and the transformation of rod-like phase 1 to rhombic-like phase 2 achieved under conditions of cyclic voltammetry was monitored in situ by AFM. The similarity of in situ AFM results with ex situ SEM studies accomplished previously implies that the morphology of the samples remains unchanged when the solvent environment is removed. In the process of crystal transformation, the triple phase solid∣electrode∣electrolyte junction is confirmed to be the initial nucleation site. Raman spectra and AFM images suggest that 100% interconversion is not always achieved, even after extended electrolysis of large 50 × 50 μm2 TCNQ crystals.

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The continuous growth of the XML data poses a great concern in the area of XML data management. The need for processing large amounts of XML data brings complications to many applications, such as information retrieval, data integration and many others. One way of simplifying this problem is to break the massive amount of data into smaller groups by application of clustering techniques. However, XML clustering is an intricate task that may involve the processing of both the structure and the content of XML data in order to identify similar XML data. This research presents four clustering methods, two methods utilizing the structure of XML documents and the other two utilizing both the structure and the content. The two structural clustering methods have different data models. One is based on a path model and other is based on a tree model. These methods employ rigid similarity measures which aim to identifying corresponding elements between documents with different or similar underlying structure. The two clustering methods that utilize both the structural and content information vary in terms of how the structure and content similarity are combined. One clustering method calculates the document similarity by using a linear weighting combination strategy of structure and content similarities. The content similarity in this clustering method is based on a semantic kernel. The other method calculates the distance between documents by a non-linear combination of the structure and content of XML documents using a semantic kernel. Empirical analysis shows that the structure-only clustering method based on the tree model is more scalable than the structure-only clustering method based on the path model as the tree similarity measure for the tree model does not need to visit the parents of an element many times. Experimental results also show that the clustering methods perform better with the inclusion of the content information on most test document collections. To further the research, the structural clustering method based on tree model is extended and employed in XML transformation. The results from the experiments show that the proposed transformation process is faster than the traditional transformation system that translates and converts the source XML documents sequentially. Also, the schema matching process of XML transformation produces a better matching result in a shorter time.

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While over the past decade many Australian schools have come to understand the transformative potential of digitally-rich teaching and learning, traditional models of schooling continue to dominate. Even with significant investment in the area, both in terms of digital resourcing and teacher professional development, innovation has generally only occurred in individual classrooms or ‘pockets’ in schools. This article discusses three interdependent conditions which need to exist as a foundation in order to facilitate the opportunity for transformation from traditional to digitally-rich ways of working in primary, middle and secondary schools or colleges. Distributed and transformational leadership approaches are critiqued with core elements identified which facilitate change. The establishment of a vision is identified and discussed as a fundamental driver and rudder for school transformation. The importance of creating and maintaining urgency to compel a school community to adopt and embed change is unpacked. This report concludes with a synthesis of the three preconditions and recommendations for proponents of digital school transformation.

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A series of improved vectors have been constructed that are suitable for use in Agrobacterium tumefaciens-mediated monocot transformation. These binary vectors have several useful features, including the selectable marker genes bar (phosphinothricin resistance) or hph (hygromycin resistance) driven by either the cauliflower mosaic virus (CaMV) 35S promoter or the maize ubiquitin promoter, a high-copy-number replication origin that allows reliable mini-prep DNA isolation from Escherichia coli, and a polylinker sequence into which target genes can be easily inserted. A significant improvement has been made to the hph gene by the introduction of an intron into its coding region. The presence of the intron abolishes hph expression in A. tumefaciens, rendering the bacterium susceptible to the selective agent hygromycin B. The use of such an intron-hph vector thus enables the antibiotic in plant culture media to function as both a selective agent for transformed tissue and as a contraselective agent for A. tumefaciens growth, thus minimising the overgrowth of A. tumefaciens on plant tissues during transformation. Furthermore, the intron appears to be correctly spliced in plant cells and significantly enhances hph expression in transformed rice tissue. In our experiments, the use of the intron-hph vector increased the frequency of rice transformation and has enabled the production of transgenic barley.

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Efficient transformation of barley cv. Schooner was achieved using Agrobacterium delivery, hygromycin or bialaphos selection and embryogenic callus. Using this system, transgenic plants were generated that contained either the green fluorescent protein gene, or transgenes derived from barley yellow dwarf (BYDV) and cereal yellow dwarf (CYDV) viruses. Many of these plants contained 1-3 transgene copies that were inherited in a simple Mendelian manner. Some plants containing BYDV and/or CYDV derived transgenes showed reduced virus symptoms and rates of viral replication when challenged with the appropriate virus. The ability to transform Schooner is a significant advance for the Australian barley industry, as this elite malting variety is, and has for the last 15 years been, the most widely grown barley variety in eastern Australia.