964 resultados para DIAMOND


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Room temperature synchrotron x-ray diffraction experiments were performed on nanocrystal Ta2N in a diamond anvil cell to a pressure of 55.48 GPa. This nitride is a well-known kind of high-hardness material, and it is found to be highly incompressible. The structure is stable with no phase transitions observed in this pressure range. The zero-pressure bulk modulus and its pressure derivative at ambient pressure are B0 = 360 ± 3 GPa, B0' = 4, and in room conditions, the a and c parameters are 3.054 Å, 4.996 Å, respectively. The bulk modulus of Ta2N is greater than those of TaC, ε-TaN, Cr2N and MoN. The differences in bulk moduli might be due to the differences in structure and the cohesive energy among these phases.

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The high-pressure behavior of scandium oxide (Sc2O3) has been investigated by angle-dispersive synchrotron powder X-ray diffraction and Raman spectroscopy techniques in a diamond anvil cell up to 46.2 and 42 GPa, respectively. An irreversible structural transformation of Sc2O3 from the cubic phase to a monoclinic high-pressure phase was observed at 36 GPa. Subsequent ab initio calculations for Sc2O3 predicted the phase transition from the cubic to monoclinic phase but at a much lower pressure. The same calculations predicted a second phase transition at 77 GPa from the monoclinic to hexagonal phase.

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Structural behaviour of cyclo-octane under high pressure is studied by using a synchrotron x-ray source in a diamond anvil cell (DAC) up to 40.2 GPa at room temperature. The cyclo-octane firstly solidifies to the triclinic phase at 0.87GPa. With the increasing pressure, the phase of cyclo-octane changes to the tetragonal phase at about 6.0 GPa and then transforms to amorphous phase above 18.2 GPa, which is kept till to 40.2 GPa. All the phase transitions of cyclo-octane are irreversible.

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Single-crystal samples of the 1:1 adduct between cyanuric acid and melamine (CA·M), an outstanding case of noncovalent synthesis, have been studied by Raman spectroscopy and synchrotron X-ray diffraction in a diamond anvil cell up to pressures of 15 GPa. The abrupt changes in Raman spectra around 4.4 GPa have provided convincing evidence for pressure-induced structural phase transition. This phase transition was confirmed by angle dispersive X-ray diffraction (ADXRD) experiments to be a space group change from C2/m to its subgroup P21/m. On release of pressure, the observed transition was irreversible, and the new high-pressure phase was fully preserved at ambient conditions. We propose that this phase transition was due to supramolecular rearrangements brought about by changes in the hydrogen bonding networks.

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This paper proposes a novel nano-sinusoid particle to be employed in enhanced localized surface plasmon resonance (LSPR) bio-sensing devices. Numerical investigations are carried out to demonstrate advantages offered by the proposed nano-particle on LSPR enhancement over other nano-particles including noble nano-triangles and nano-diamonds. Although nano-triangles exhibit high concentration of the electric field near their tips, when illuminated with a light polarized along the tip axis, they present only one hot spot at the vertex along the polarization direction. To create a structure with two hot spots, which is desired in bio-sensing applications, two nano-triangles can be put back-to-back. Therefore, a nano-diamond particle is obtained which exhibits two hot spots and presents higher enhancements than nano-triangles for the same resonant wavelength. The main drawback of the nano-diamonds is the fluctuation in their physical size-plasmon spectrum relationships, due to a high level of singularity as the result for their four sharp tip points. The proposed nano-sinusoid overcomes this disadvantage while maintaining the benefits of having two hot spots and high enhancements.

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This paper proposes a novel sinusoidal shape nano-particle employed in localized surface plasmon resonance (LSPR) devices. Numerical modeling demonstrates advantages offered by the proposed nano-sinusoid on LSPR enhancement against other nano-particles including noble nano-triangles and nano-diamonds. Although nano-triangles exhibit high concentration of the electric field near their tips, when illuminated with a light polarized along the tip axis, they present only one hot spot at the vertex along the polarization direction. To create a structure with two hot spots, which is desired in bio-sensing applications, two nano-triangles can be put back-to-back. Therefore, a nano-diamond particle is obtained which exhibits two hot spots and presents higher enhancements than nano-triangles for the same resonant wavelength. The main drawback of the nano-diamonds is the fluctuation in their physical size-plasmon spectrum relationships, due to a high level of singularity as the result for their four sharp tip points. The proposed nano-sinusoid overcomes this disadvantage while maintaining the benefits of having two hot spots and high enhancements.

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When discussing her verse novels, Dorothy Porter explicitly stated that she loved to ‘write bad’. This paper will argue that it was Porter’s engagement with the verse novel form and genre subversion, most notably seen with her detective and crime thriller verse novels The monkey’s mask and El Dorado, that allows for a destabilisation of traditionally established genre conventions, which in turn provide a narrative foundation for Porter’s use of abject erotic imagery.

In both The monkey’s mask and El Dorado there are several types of ‘bodies’ to be examined: the body of the verse narrative, the bodies of the characters subjected to crime, the body of poetry that is referred to as evidence, and the abject eroticised body. Extending upon the studies of Rose Lucas (1997) and Fleur Diamond (1999), this paper contends that it is Porter’s engagement with the abject erotic, as informed by Julia Kristeva’s (1982) theory of the abject and Johanna Blakley’s (1995) discussion of the abject in relation to eroticism, that allows Porter to subvert the phallocentric limitations upheld through the crime fiction genre and offer an alternative representation for lesbian sexuality and desire.

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After decades of growth and development, Iraq has become amongst the worst performing states worldwide as a legacy of successive wars and sanctions despite the rich endowment with ample natural resources and capable human resources. Many observers expected that the “new” Iraq after the US “liberation” in 2003 will be a tolerant and unified nation-state that “with a degree of civil society” will grant and secure the human rights for all the Iraqi people (Gresham 2006: 27). However, due to the external military intervention lead by the US, the Iraq state collapsed after the 2003 war (Diamond 2005) as well as its economic, educational, health systems and infrastructure; and, Iraq’s development indicators are amongst the lowest globally (Hassin 2010). Australia’s controversial joining of Bush’s Coalition of Willing has been discussed by various intellectual studies from different angles. It is discussed in the socio-political discourse from an international relations perspective (Verrier 2003), social resistance to war (Hil 2008), and the implications on the Australian internal politics (McAllister and Bean 2006) and federal elections (Kelton 2008). However, there is scarce evidence about any research engaging with Australia’s roles in post-conflict nation building in Iraq. This article explores developmental roles and initiatives played and funded by Australia in Iraq since the invasion in 2003. Based on Hippler’s (Hippler 2004- 2005) multi-faceted approach to nation building this paper will study Australia’s roles in the three interlinked dimensions or “starting points” for nation building: improvement of living conditions, structural reforms and integration of the national political system.

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The structural transition of AIN nanocrystals and nanowires were investigated simultaneously under pressures up to 37.2 GPa by in situ angle dispersive high-pressure x-ray diffraction using synchrotron radiation source and a single diamond anvil cell. The size of hexagonal AIN nanocrystals and the diameter of nanowires are 45 nm on average. A pressure-induced wurtzite to rocksalt phase transition starts at 21.5 GPa and completes at 27.8 GPa for the nanocrystals and nanowires, respectively. The high-pressure behaviors of AlN nanocrystals the same as the AIN nanowires might arise from the similar size and diameter in nanocrystals and nanowires. Hexagonal AIN nanocrystals (45 nm) display an apparent volumetric contraction as compared to the AlN nanocrystals (10 nm) which might induce the difference of transition pressure.

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Metabolite profiling, HPLC, LC-QTOF-MS, GC-MS. A workflow will be presented for comprehensive metabolomics using LC- and GC-MS. Metabolomics is an emerging field in the suite of ‘omic’ approaches for Systems Biology. The goal of metabolomics is to detect the presence of all small-molecules in a biological sample. This presents a significant challenge due to the chemical diversity and large concentration range of metabolites. Currently, there is no single method which enables the entire metabolome to be analysed, therefore a suite of analytical approaches are required to increase the coverage of detected metabolites. The routinely used techniques for metabolite profiling are LC- and GC-MS and NMR. Here we present complementary approaches using MS hyphenated to different chromatographic techniques. GC-MS represent the most robust standardised technique for high throughput metabolite profiling however there are still no standard LC-based methods for profiling. Polar compounds represent the most challenging aspect of LC-based metabolomics. A robust chromatographic technique for profiling polar compounds using HILIC chromatography and QTOF-MS will be presented as well as the complimentary reverse phase LC-MS method. The polar separation was carried out using a diamond hydride column. This unique stationary phase provides stable retention times and fast re-equilibration which contrasts to other forms of HILIC stationary phases. These LC-based methods will be compared to the well established GC-MS method as well as NMRbased profiling.

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The aim of this article is to investigate the drilling of carbon fiber-reinforced plastic (CFRP) composite/metal stack-ups to have a details picture of the developments in this complex area. The forces and torque, chip shape, surface finish and geometry, and tool material and tool wear for drilling composite/metal stack-ups have been analyzed in details in addition to drilling mechanism of CFRP. The relation between input and output parameters was discussed and the trend of input parameters for damage free and tight tolerance holes has been investigated based on the literature. The main findings are (i) heat, built-up edge and chips generated from drilling of metallic layers damages CFRP surface, (ii) order of material layers affects the drilling outcomes significantly, (iii) coatings and step-shape on the cutting tool improves the tool performance, (iv) tool materials should be selected based on the material of metallic layer, (v) chipping, adhesion, abrasion and attrition are main tool wear mechanisms during machining of CFRP/metal stacks and (vi) application of coolant improves the machinability.

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The intrinsic stress, film density and nitrogen content of carbon nitride (CNx) films deposited from a filtered cathodic vacuum arc were determined as a function of substrate bias, substrate temperature and nitrogen process pressure. Contour plots of the measurements show the deposition conditions required to produce the main structural forms of CNx including N-doped tetrahedral amorphous carbon (ta-C:N) and a variety of nitrogen containing graphitic carbons. The film with maximum nitrogen content (~ 30%) was deposited at room temperature with 1.0 mTorr N2 pressure and using an intermediate bias of - 400 V. Higher nitrogen pressure, higher bias and/or higher temperature promoted layering with substitutional nitrogen bonded into graphite-like sheets. As the deposition temperature exceeded 500 °C, the nitrogen content diminished regardless of nitrogen pressure, showing the meta-stability of the carbon-nitrogen bonding in the films. Hardness and ductility measurements revealed a diverse range of mechanical properties in the films, varying from hard ta-C:N (~ 50 GPa) to softer and highly ductile CN x which contained tangled graphite-like sheets. Through-film current-voltage characteristics showed that the conductance of the carbon nitride films increased with nitrogen content and substrate bias, consistent with the transition to more graphite-like films. © 2014 Elsevier B.V.

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With the spectacular rise of the Chinese and Indian economies the accompanying growth in these two countries' construction sectors justifies more understanding. There is, however, a lot of unknowns about the two countries' construction sectors from a comparative perspective. This study attempted to identify and compare the comparative/competitive advantages of the two fast-growing economies in construction in pursuit of policy and management implications, which can benefit not only the two countries but also other developing countries. In this regard, a comparative advantage framework and Porter's Diamond Framework were applied to analyze the relative advantages of the Chinese and Indian construction sectors. The comparative analyses showed that China appears better endowed in labor with high productivity. Government intervention was identified as benefiting Chinese firms with support for the development of human resources. China also benefits from superior access to a wide range of inputs, including equipment, construction materials, and technology. The existence of large corporate champions provides scale of economy and contributes to the advantage of the construction sector of China. In contrast, India benefits from the increased competitive rivalry thanks to its more hands-off government policies that focus primarily on providing a good business environment with a favorable tax system, market entry policies, laws and regulations, and code/standard systems. The differences identified provide policy implications to the decision makers of the two countries in further developing their construction sectors. © 2014 American Society of Civil Engineers.