694 resultados para High purity


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This chapter focuses on demonstrating the role of Design-Led Innovation (DLI) as an enabler for the success of Small to Medium Enterprises (SMEs) within high growth environments. This chapter is targeted toward businesses that may have been exposed to the concept of design previously at a product level and now seek to better understand its value through implementation at a strategic level offering. The decision to engage in the DLI process is made by firms who want to remain competitive as they struggle to compete in high cost environments, such as the state of the Australian economy at present. The results presented in this chapter outline the challenges in the adoption of the DLI process and the implications it can have. An understanding of the value of DLI in practice—as an enabler of business transformation in Australia—is of benefit to government and the broader design community.

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Mammographic density (MD) is the area of breast tissue that appears radiologically white on mammography. Although high MD is a strong risk factor for breast cancer, independent of BRCA1/2 mutation status, the molecular basis of high MD and its associated breast cancer risk is poorly understood. MD studies will benefit from an animal model, where hormonal, gene and drug perturbations on MD can be measured in a preclinical context. High and low MD tissues were selectively sampled by stereotactic biopsy from operative specimens of high-risk women undergoing prophylactic mastectomy. The high and low MD tissues were transferred into separate vascularised biochambers in the groins of SCID mice. Chamber material was harvested after 6 weeks for histological analyses and immunohistochemistry for cytokeratins, vimentin and a human-specific mitochondrial antigen. Within-individual analysis was performed in replicate mice, eliminating confounding by age, body mass index and process-related factors, and comparisons were made to the parental human tissue. Maintenance of differential MD post-propagation was assessed radiographically. Immunohistochemical staining confirmed the preservation of human glandular and stromal components in the murine biochambers, with maintenance of radiographic MD differential. Propagated high MD regions had higher stromal (p = 0.0002) and lower adipose (p = 0.0006) composition, reflecting the findings in the original human breast tissue, although glands appeared small and non-complex in both high and low MD groups. No significant differences were observed in glandular area (p = 0.4) or count (p = 0.4) between high and low MD biochamber tissues. Human mammary glandular and stromal tissues were viably maintained in murine biochambers, with preservation of differential radiographic density and histological features. Our study provides a murine model for future studies into the biomolecular basis of MD as a risk factor for breast cancer.

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A unique high temporal frequency dataset from an irrigated cotton-wheat rotation was used to test the agroecosystem model DayCent to simulate daily N2O emissions from sub-tropical vertisols under different irrigation intensities. DayCent was able to simulate the effect of different irrigation intensities on N2O fluxes and yield, although it tended to overestimate seasonal fluxes during the cotton season. DayCent accurately predicted soil moisture dynamics and the timing and magnitude of high fluxes associated with fertilizer additions and irrigation events. At the daily scale we found a good correlation of predicted vs. measured N2O fluxes (r2 = 0.52), confirming that DayCent can be used to test agricultural practices for mitigating N2O emission from irrigated cropping systems. A 25 year scenario analysis indicated that N2O losses from irrigated cotton-wheat rotations on black vertisols in Australia can be substantially reduced by an optimized fertilizer and irrigation management system (i.e. frequent irrigation, avoidance of excessive fertiliser application), while sustaining maximum yield potentials.

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This thesis advances the understanding of the impact of stigma on property values. A case study in Wellington, New Zealand, enabled hedonic modelling and an empirical analysis to determine the impact of the stigma from the high voltage transmission line structure and how long the stigma remained after removal. The results reveal a substantial difference between the discount applied to individual properties while the structure is in place, as compared to the overall increase in neighbourhood value once the structure, which created the stigma, is removed.

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Creep and shrinkage behaviour of an ultra lightweight cement composite (ULCC) up to 450 days was evaluated in comparison with those of a normal weight aggregate concrete (NWAC) and a lightweight aggregate concrete (LWAC) with similar 28-day compressive strength. The ULCC is characterized by low density < 1500 kg/m3 and high compressive strength about 60 MPa. Autogenous shrinkage increased rapidly in the ULCC at early-age and almost 95% occurred prior to the start of creep test at 28 days. Hence, majority of shrinkage of the ULCC during creep test was drying shrinkage. Total shrinkage of the ULCC during the 450-day creep test was the lowest compared to the NWAC and LWAC. However, corresponding total creep in the ULCC was the highest with high proportion attributed to basic creep (≥ ~90%) and limited drying creep. The high creep of the ULCC is likely due to its low elastic modulus. Specific creep of the ULCC was similar to that of the NWAC, but more than 80% higher than the LWAC. Creep coefficient of the ULCC was about 47% lower than that of the NWAC but about 18% higher than that of the LWAC. Among five creep models evaluated which tend to over-estimate the creep coefficient of the ULCC, EC2 model gives acceptable prediction within +25% deviations. The EC2 model may be used as a first approximate for the creep of ULCC in the designs of steel-concrete composites or sandwich structures in the absence of other relevant creep data.

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A general chemo-enzymatic process has been developed to prepare enantiomerically pure L- and D-amino acids in high yield by deracemisation of racemic starting materials. The method has been developed from initial academic studies to be a robust, scalable industrial process. Unnatural amino acids, in high optical purity, are a rapidly growing class of intermediates required for pharmaceuticals, agrochemicals and other fine chemical applications. However, no single method has proven sufficiently adaptable to prepare these compounds generally at large scale. Our approach uses an enantioselective oxidase biocatalyst and a non-selective chemical reducing agent to effect the stereoinversion of one enantiomer and can result in an enantiomeric excess of > 99 % from a starting racemate, and product yields over 90 %. The current approach compares very favourably to resolution methods which have a maximum single pass yield of 50 %. Efficient methods have been developed to adapt the biocatalyst used in this process towards new target compounds and to optimise key factors which improve the process efficiency and offer competitive economics at scale.

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We construct a two-scale mathematical model for modern, high-rate LiFePO4cathodes. We attempt to validate against experimental data using two forms of the phase-field model developed recently to represent the concentration of Li+ in nano-sized LiFePO4crystals. We also compare this with the shrinking-core based model we developed previously. Validating against high-rate experimental data, in which electronic and electrolytic resistances have been reduced is an excellent test of the validity of the crystal-scale model used to represent the phase-change that may occur in LiFePO4material. We obtain poor fits with the shrinking-core based model, even with fitting based on “effective” parameter values. Surprisingly, using the more sophisticated phase-field models on the crystal-scale results in poorer fits, though a significant parameter regime could not be investigated due to numerical difficulties. Separate to the fits obtained, using phase-field based models embedded in a two-scale cathodic model results in “many-particle” effects consistent with those reported recently.

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MMP-2 (gelatinase A) has been associated with the invasive potential of many cancer cells both in vitro and in vivo. It is now becoming clear that the activation of this enzyme might be a key step in tumor invasion. This activation process has been shown to be a membrane-associated pathway inducible by various agents such as collagen type I, concanavalin A or TGF-β, but its physiological regulation is still largely unresolved. MT-MMP was recently discovered and described as a potential gelatinase-A activator. In the present study, we investigated the expression of MT-MMP (membrane-type metalloproteinase) in cervical cancer cells both in vitro and in vivo. Comparing several in vitro-transformed cervical cell lines, previously shown to display different invasive potentials, our results showed that the ability of cells to overexpress MT-MMP mRNA following ConA induction correlated with their ability to activate gelatinase A and with a highly invasive behavior. Moreover, using immunohistochemistry and in situ hybridization, we found a higher level of MT-MMP expression in invasive cervical carcinoma and lymphnode metastases compared to its expression in non-invasive CIN III lesions. Our in vivo observations also clearly demonstrated a cooperation between stromal and tumor cells for the production of MT-MMP. Taken together, our results clearly correlated high level MT-MMP expression with invasiveness, and thus suggested that MT-MMP might play a crucial role in cervical tumor invasion.

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The development of global navigation satellite systems (GNSS) provides a solution of many applied problems with increasingly higher quality and accuracy nowadays. Researches that are carried out by the Bavarian Academy of Sciences and Humanities in Munich (BAW) in the field of airborne gravimetry are based on sophisticated data processing from high frequency GNSS receiver for kinematic aircraft positioning. Applied algorithms for inertial acceleration determination are based on the high sampling rate (50Hz) and on reducing of such factors as ionosphere scintillation and multipath at aircraft /antenna near field effects. The quality of the GNSS derived kinematic height are studied also by intercomparison with lift height variations collected by a precise high sampling rate vertical scale [1]. This work is aimed at the ways of more accurate determination of mini-aircraft altitude by means of high frequency GNSS receivers, in particular by considering their dynamic behaviour.

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Despite considerable state investment and initiatives, binge drinking is still a major behavioral problem for policy makers and communities in many parts of the world. Furthermore, the practice of bingeing on alcohol seems to be spreading to young people in countries traditionally considered to have moderate drinking behaviors. Using a sociocultural lens and a framework of sociocultural themes from previous literature to develop propositions from their empirical study, the authors examine binge-drinking attitudes and behaviors among young people from high and moderate binge-drinking countries. The authors then make proposals regarding how policy makers can use social marketing more effectively to contribute to behavior change. Qualitative interviews were conducted with 91 respondents from 22 countries who were studying in two high binge-drinking countries at the time. The results show support for three contrasting sociocultural propositions that identify influences on binge drinking across these countries.

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Is there a crisis in Australian science and mathematics education? Declining enrolments in upper secondary Science and Mathematics courses have gained much attention from the media, politicians and high-profile scientists over the last few years, yet there is no consensus amongst stakeholders about either the nature or the magnitude of the changes. We have collected raw enrolment data from the education departments of each of the Australian states and territories from 1992 to 2012 and analysed the trends for Biology, Chemistry, Physics, two composite subject groups (Earth Sciences and Multidisciplinary Sciences), as well as entry, intermediate and advanced Mathematics. The results of these analyses are discussed in terms of participation rates, raw enrolments and gender balance. We have found that the total number of students in Year 12 increased by around 16% from 1992 to 2012 while the participation rates for most Science and Mathematics subjects, as a proportion of the total Year 12 cohort, fell (Biology (-10%), Chemistry (-5%), Physics (-7%), Multidisciplinary Science (-5%), intermediate Mathematics (-11%), advanced Mathematics (-7%) in the same period. There were increased participation rates in Earth Sciences (+0.3%) and entry Mathematics (+11%). In each case the greatest rates of change occurred prior to 2001 and have been slower and steadier since. We propose that the broadening of curriculum offerings, further driven by students' self-perception of ability and perceptions of subject difficulty and usefulness, are the most likely cause of the changes in participation. While these continuing declines may not amount to a crisis, there is undoubtedly serious cause for concern.

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In organic-inorganic nanocomposites, interfacial regions are primarily influenced by the dispersion uniformity of nanoparticles and the strength of interfacial bonds between the nanoparticles and the polymer matrix. The insulating performance of organic-inorganic dielectric nanocomposites is highly influenced by the characteristics of interfacial regions. In this study, we prepare polyethylene oxide (PEO)-like functional layers on silica nanoparticles through plasma polymerization. Epoxy resin/silica nanocomposites are subsequently synthesized with these plasma-polymerized nanoparticles. It is found that plasma at a low power (i.e., 10 W) can significantly increase the concentration of C-O bonds on the surface of silica nanoparticles. This plasma polymerized thin layer can not only improve the dispersion uniformity by increasing the hydrophilicity of the nanoparticles, but also provide anchoring sites to enable the formation of covalent bonds between the organic and inorganic phases. Furthermore, electrical tests reveal improved electrical treeing resistance and decreased dielectric constant of the synthesized nanocomposites, while the dielectric loss of the nanocomposites remains unchanged as compared to the pure epoxy resin.

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Despite major advances in the fabrication and characterization of SiC and related materials, there has been no convincing evidence of the synthesis of nanodevice-quality nanoislanded SiC films at low, ultralarge scale integration technology-compatible process temperatures. The authors report on a low-temperature (400 °C) plasma-assisted rf magnetron sputtering deposition of high-quality nanocrystalline SiC films made of uniform-size nanoislands that almost completely cover the Si(100) surface. These nanoislands are chemically pure, highly stoichiometric, have a typical size of 20-35 nm, and contain small (∼5 nm) nanocrystalline inclusions. The properties of nanocrystalline SiC films can be effectively controlled by the plasma parameters.

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To overcome major problems associated with insufficient incorporation of nitrogen in hydrogenated amorphous silicon nitride (a-SiNx:H) nanomaterials, which in turn impedes the development of controlled-bandgap nanodevices, here we demonstrate the possibility to achieve effective bandgap control in a broad range by using high-density inductively coupled plasmas. This achievement is related to the outstanding dissociation ability of such plasmas. It is shown that the compositional, structural, optical, and morphological properties of the synthesized a-SiNx:H nanomaterials can be effectively tailored through the manipulation of the flow rate ratio of the silane to nitrogen gases X. In particular, a wide bandgap of 5.21 eV can be uniquely achieved at a low flow rate ratio of the nitrogen to silane gas of 1.0, whereas typically used values often exceed 20.0. These results are highly-relevant to the development of the next-generation nanodevices that rely on the effective control of the functional nano-layer bandgap energies.

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A simple, effective and innovative approach based on low-pressure, thermally nonequilibrium, high-density inductively coupled plasmas is proposed to rapidly synthesize Si quantum dots (QDs) embedded in an amorphous SiC (a-SiC) matrix at a low substrate temperature and without any commonly used hydrogen dilution. The experimental results clearly demonstrate that uniform crystalline Si QDs with a size of 3-4 nm embedded in the silicon-rich (carbon content up to 10.7at.%) a-SiC matrix can be formed from the reactive mixture of silane and methane gases, with high growth rates of ∼1.27-2.34 nm s-1 and at a low substrate temperature of 200 °C. The achievement of the high-rate growth of Si QDs embedded in the a-SiC without any commonly used hydrogen dilution is discussed based on the unique properties of the inductively coupled plasma-based process. This work is particularly important for the development of the all-Si tandem cell-based third generation photovoltaic solar cells.