On equilibrium states and dust charging in dusty plasmas

The dust-charge variation process is revisited, accounting for the background density variation associated with electron capture and release by the dust grains. It appears possible to maintain overall charge neutrality in the plasma without any external particle source or sink. It is shown that if the dust charge and density are sufficiently high, the effect of the background electron density variation on dust-charge relaxation is important. The equilibrium dust charge and its rate of variation are obtained for dusty plasmas subject to strong UV irradiation. The latter releases photoelectrons from the dust surface and can significantly affect the equilibrium dust charge, its variation rate, as well as the overall charge neutrality in the plasma.

Equilibrium and relaxation of particulate charge in fluorocarbon plasmas

Charging of micron-size particulates, often appearing in fluorocarbon plasma etching experiments, is considered. It is shown that in inductively coupled and microwave slot-excited plasmas of C4F8 and Ar gas mixtures, the equilibrium particle charge and charge relaxation processes are controlled by a combination of microscopic electron, atomic (Ar+ and F+), and molecular ion (CF+ 3, CF+ 2, and CF+) currents. The impact of molecular ion currents on the particulate charging and charge relaxation processes is analyzed. It is revealed that in low-power (<0.5 kW) microwave slot-excited plasmas, the impact of the combined molecular ion current to the total positive microscopic current on the particle can be as high as 40%. The particulate charge relaxation rate in fluorocarbon plasmas appears to exceed 108 s-1, which is almost one order of magnitude higher than that from purely argon plasmas. This can be attributed to the impact of positive currents of fluorocarbon molecular ions, as well as to the electron density fluctuations with particle charge, associated with electron capture and release by the particulates.

Extremely non-equilibrium synthesis of luminescent zinc oxide nanoparticles through energetic ion condensation in a dense plasma focus device

Luminescent ZnO nanoparticles have been synthesized on silicon and quartz substrates under extremely non-equilibrium conditions of energetic ion condensation during the post-focus phase in a dense plasma focus (DPF) device. Ar+, O+, Zn+ and ZnO+ ions are generated as a result of interaction of hot and dense argon plasma focus with the surfaces of ZnO pellets placed at the anode. It is found that the sizes, structural and photoluminescence (PL) properties of the ZnO nanoparticles appear to be quite different on Si(1 0 0) and quartz substrates. The results of x-ray diffractometry and atomic force microscopy show that the ZnO nanoparticles are crystalline and range in size from 5-7 nm on Si(1 0 0) substrates to 10-38 nm on quartz substrates. Room-temperature PL studies reveal strong peaks related to excitonic bands and defects for the ZnO nanoparticles deposited on Si (1 0 0), whereas the excitonic bands are not excited in the quartz substrate case. Raman studies indicate the presence of E2 (high) mode for ZnO nanoparticles deposited on Si(1 0 0).

Rapid, low-temperature synthesis of nc-Si in high-density, non-equilibrium plasmas : enabling nanocrystallinity at very low hydrogen dilution

Nanocrystalline silicon thin films were deposited on single-crystal silicon and glass substrates simultaneously by inductively coupled plasma-assisted chemical vapor deposition from the reactive silane reactant gas diluted with hydrogen at a substrate temperature of 200 °C. The effect of hydrogen dilution ratio X (X is defined as the flow rate ratio of hydrogen to silane gas), ranging from 1 to 20, on the structural and optical properties of the deposited films, is extensively investigated by Raman spectroscopy, X-ray diffraction, Fourier transform infrared absorption spectroscopy, UV/VIS spectroscopy, and scanning electron microscopy. Our experimental results reveal that, with the increase of the hydrogen dilution ratio X, the deposition rate Rd and hydrogen content CH are reduced while the crystalline fraction Fc, mean grain size δ and optical bandgap ETauc are increased. In comparison with other plasma enhanced chemical vapor deposition methods of nanocrystalline silicon films where a very high hydrogen dilution ratio X is routinely required (e.g. X > 16), we have achieved nanocrystalline silicon films at a very low hydrogen dilution ratio of 1, featuring a high deposition rate of 1.57 nm/s, a high crystalline fraction of 67.1%, a very low hydrogen content of 4.4 at.%, an optical bandgap of 1.89 eV, and an almost vertically aligned columnar structure with a mean grain size of approximately 19 nm. We have also shown that a sufficient amount of atomic hydrogen on the growth surface essential for the formation of nanocrystalline silicon is obtained through highly-effective dissociation of silane and hydrogen molecules in the high-density inductively coupled plasmas. © 2009 The Royal Society of Chemistry.

Parameters and equilibrium profiles for large-area surface-wave sustained plasmas

The equilibrium profiles of the plasma parameters of large-area if discharges in a finite-length metal-shielded dielectric cylinder are computed using a two-dimensional fluid code. The rf power is coupled to the plasma through edge-localized surface waves traveling in the azimuthal direction along the plasma edge. It is shown that self-consistent accounting for axial plasma diffusion and radial nonuniformity of the electron temperature can explain the frequently reported deviations of experimentally measured radial density profiles from that of the conventional linear diffusion models. The simulation results are in a good agreement with existing experimental data obtained from surface-wave sustained large-diameter plasmas. © 2002 The American Physical Society.

Low-pressure diffusion equilibrium of electronegative complex plasmas

A model for electronegative plasmas containing charged dust or colloidal grains was used. Numerical solutions based on the model demonstrate how a low-pressure diffusion equilibrium of the complex electronegative plasma system is dynamically sustained through plasma particle sources.

Charging and trapping of macroparticles in near-electrode regions of fluorocarbon plasmas with negative ions

Charging and trapping of macroparticles in the near-electrode region of fluorocarbon etching plasmas with negative ions is considered. The equilibrium charge and forces on particles are computed as a function of the local position in the plasma presheath and sheath. The ionic composition of the plasma corresponds to the etching experiments in 2.45 GHz surface-wave sustained and 13.56 MHz inductively coupled C4F8+Ar plasmas. It is shown that despite negligible negative ion currents collected by the particles, the negative fluorine ions affect the charging and trapping of particulates through modification of the sheath/presheath structure.

Looking beyond image and tourism : the role of flagship cultural projects in local arts development

State and local governments frequently look to flagship cultural projects to improve the city image and catalyze tourism but, in the process, often overlook their potential to foster local arts development. To better understand this role, the article examines if and how cultural institutions in Los Angeles and San Francisco attract and support arts-related activity. The analysis reveals that cultural flagships have mixed success in generating arts-based development and that their ability may be improved through attention to the local context, facility and institutional characteristics, and the approach of the sponsoring agencies. Such knowledge is useful for planners to enhance their revitalization efforts, particularly as the economic development potential of arts organizations and artists has become more apparent.

'Not a Local Win': Rural Australian perceptions of the sustainable impacts of forest plantations

Australian forestry plantations have doubled in the past 15 years, with rural communities harbouring a diverse range of positive and negative of economic, environmental and social impacts – the so-called triple bottom line (TBL). Utilising two Australian rural communities in Eden/Gippsland and Tasmania as qualitative case studies, this research explores how 23 non-forestry affiliated rural residents perceived and experienced the TBL economic, environmental and social impacts of plantation forestry. Residents criticised the economic plantation forestry benefits because of lengthy periods of inactivity and limited local employment, explaining that their community was reliant on the industry yet the promised economic benefits had never fully materialised. There was a sense the industry ‘plant and walk away.’ Residents were concerned about the environment impact on water quality, water tables and fire hazards, although they praised plantation forestry for carbon sequestering, eradicating erosion and water run-off. Negative social impacts were described, specifically how the land-use change from farming to forestry had significantly reduced the local population, employment and need for services. Natural resource management and communication strategies are offered, derived from non-forestry affiliated rural resident perspectives on how best to ensure sustainable forest development in their community.

Effect of broadcast baiting on abundance patterns of red imported fire ants (Hymenoptera: Formicidae) and key local ant genera at long-term monitoring sites in Brisbane, Australia

In 2001, the red imported fire ant (Solenopsis invicta Buren) was identified in Brisbane, Australia. An eradication program involving broadcast bait treatment with two insect growth regulators and a metabolic inhibitor began in September of that year and is currently ongoing. To gauge the impacts of these treatments on local ant populations, we examined long-term monitoring data and quantified abundance patterns of S. invicta and common local ant genera using a linear mixed-effects model. For S. invicta, presence in pitfalls reduced over time to zero on every site. Significantly higher numbers of S. invicta workers were collected on high-density polygyne sites, which took longer to disinfest compared with monogyne and low-density polygyne sites. For local ants, nine genus groups of the 10 most common genera analyzed either increased in abundance or showed no significant trend. Five of these genus groups were significantly less abundant at the start of monitoring on high-density polygyne sites compared with monogyne and low-density polygyne sites. The genus Pheidole significantly reduced in abundance over time, suggesting that it was affected by treatment efforts. These results demonstrate that the treatment regime used at the time successfully removed S. invicta from these sites in Brisbane, and that most local ant genera were not seriously impacted by the treatment. These results have important implications for current and future prophylactic treatment efforts, and suggest that native ants remain in treated areas to provide some biological resistance to S. invicta.

Optimisation methods for coupled thermodynamic and 1D design of radial-inflow turbines

Optimisation is a fundamental step in the turbine design process, especially in the development of non-classical designs of radial-inflow turbines working with high-density fluids in low-temperature Organic Rankine Cycles (ORCs). The present work discusses the simultaneous optimisation of the thermodynamic cycle and the one-dimensional design of radial-inflow turbines. In particular, the work describes the integration between a 1D meanline preliminary design code adapted to real gases and the performance estimation approach for radial-inflow turbines in an established ORC cycle analysis procedure. The optimisation approach is split in two distinct loops; the inner operates on the 1D design based on the parameters received from the outer loop, which optimises the thermodynamic cycle. The method uses parameters including brine flow rate, temperature and working fluid, shifting assumptions such as head and flow coefficients into the optimisation routine. The discussed design and optimisation method is then validated against published benchmark cases. Finally, using the same conditions, the coupled optimisation procedure is extended to the preliminary design of a radial-inflow turbine with R143a as working fluid in realistic geothermal conditions and compared against results from commercially-available software RITAL from Concepts-NREC.

An e-support firm's response to local e-readiness and the global e-business environment

The purpose of this study is to understand a small e-support firm’s response to the local e-readiness and the global e-business environment in a developing context. E-Support firms provide Web development and consultancy services to user organizations, assisting them in their uptake and maintenance of their Internet applications. Within the e-readiness research area, little is known about e-support firms, particularly in connection with their interaction with their local and the global e-business environment. As yet the emphasis on e-readiness studies has been at the national level. Nevertheless, the e-support sector is very significant in the successful adoption and diffusion of the Internet and related applications in any economy. It is thus important to understand how such firms relate to their e-business environments.That said, this study draws on the interpretive case study of a small e-support firm in Ghana, a developing context, to investigate the firm’s response to the e-readiness level of the local and the global e-business environment. Findings show that the firm could employ resources from the global environment to address most of the infrastructural challenges posed by a relatively poor local e-readiness context. However, its attempt to transfer advanced e-business technologies from the global e-business environment to the local e-business context did not succeed. This chapter offers implications for practice and research concerning the notion of reconciling local and global e-business environments in the small e-support sector.

A different breed altogether? Distinctions between local and metropolitan journalism cultures

While a number of scholars have explored the special exigencies of local as opposed to metropolitan journalism, rarely have studies examined such differences in relation to journalism culture as constituted by journalists’ professional views. To address the gap in our knowledge, this study reports results from a representative survey of local and metropolitan newspaper journalists in Australia. Findings suggest that territorial context accounts for some significant differences in journalists’ demographics, as well as their role perceptions. In line with past research, local newspaper journalists exhibit much stronger support for the community forum and advocacy role. At the same time, and contrary to expectations, there is very little difference in their support of the watchdog role compared with metropolitan journalists. By combining questions about journalistic ideals and enactment in their work, and finding differences in the two, this study also has important implications for the methodological development of survey studies.

Leaders in Local : Exploring Consumers‘ Purchase Intentions of Locally Produced Foods

* Local foods are growing in importance in the mind set of the consumer – “the new organic” (McKenzie-Minifie, 2007) * Consumers are becoming more active in choosing alternative channels to purchase locally grown/produced foods Growth of farmer’s markets, roadside stalls, community gardens and *CSA programs * Supermarkets and grocers continue to tailor their assortments to include, ethnic, organic, natural and local foods to meet changing consumer needs * Australian research is limited, although one early study has found ‘buying locally produced foods’ was considered an important attribute (Lea & Worsley, 2007) * International research has tended to focus on COO effects, rather than region or local effects. (Insch & Florek, 2009) *Emerging research is beginning to explore consumer interest in ‘local’ over simply ‘domestic’ – although not specifically in food. (Hustvedt, Carroll & Bernard, 2013) * One study has examined differences in attitudes, subjective norms and intentions toward the purchase of locally produced foods. (Campbell, 2013)