Growth of C36-films on diamond surface through molecular dynamics simulation

In this paper, the initial stage of films assembled by energetic C36 fullerenes on diamond (001)–(2 × 1) surface at low-temperature was investigated by molecular dynamics simulation using the Brenner potential. The incident energy was first uniformly distributed within an energy interval 20–50 eV, which was known to be the optimum energy range for chemisorption of single C36 on diamond (001) surface. More than one hundred C36 cages were impacted one after the other onto the diamond surface by randomly selecting their orientation as well as the impact position relative to the surface. The growth of films was found to be in three-dimensional island mode, where the deposited C36 acted as building blocks. The study of film morphology shows that it retains the structure of a free C36 cage, which is consistent with Low Energy Cluster Beam Deposition (LECBD) experiments. The adlayer is composed of many C36-monomers as well as the covalently bonded C36 dimers and trimers which is quite different from that of C20 fullerene-assembled film, where a big polymerlike chain was observed due to the stronger interaction between C20 cages. In addition, the chemisorption probability of C36 fullerenes is decreased with increasing coverage because the interaction between these clusters is weaker than that between the cluster and the surface. When the incident energy is increased to 40–65 eV, the chemisorption probability is found to increased and more dimers and trimers as well as polymerlike-C36 were observed on the deposited films. Furthermore, C36 film also showed high thermal stability even when the temperature was raised to 1500 K.

Impact induced chemisorption of C20 isomers on diamond (001)–(2×1) surface

The adsorption of low-energy C20 isomers on diamond (0 0 1)–(2×1) surface was investigated by molecular dynamics simulation using the Brenner potential. The energy dependence of chemisorption characteristic was studied. We found that there existed an energy threshold for chemisorption of C20 to occur. Between 10 and 20 eV, the C20 fullerene has high probability of chemisorption and the adsorbed cage retains its original structure, which supports the experimental observations of memory effects. However, the structures of the adsorbed bowl and ring C20 were different from their original ones. In this case, the local order in cluster-assembled films would be different from the free clusters.

Energy dependence of methyl-radical adsorption on diamond (001)-(2×1) surface

The deposition of hyperthermal CH3 on diamond (001)-(2×1) surface at room temperature has been studied by means of molecular dynamics simulation using the many-body hydrocarbon potential. The energy threshold effect has been observed. That is, with fixed collision geometry, chemisorption can occur only when the incident energy of CH3 is above a critical value (Eth). Increasing the incident energy, dissociation of hydrogen atoms from the incident molecule was observed. The chemisorption probability of CH3 as a function of its incident energy was calculated and compared with that of C2H2. We found that below 10 eV, the chemisorption probability of C2H2 is much lower than that of CH3 on the same surface. The interesting thing is that it is even lower than that of CH3 on a hydrogen covered surface at the same impact energy. It indicates that the reactive CH3 molecule is the more important species than C2H2 in diamond synthesis at low energy, which is in good agreement with the experimental observation.

Energy window effect in chemisorption of C36 on diamond (001)-(/2×1) surface

In this paper, the collision of a C36, with D6h symmetry, on diamond (001)-(/2×1) surface was investigated using molecular dynamics (MD) simulation based on the semi-empirical Brenner potential. The incident kinetic energy of the C36 ranges from 20 to 150 eV per cluster. The collision dynamics was investigated as a function of impact energy Ein. The C36 cluster was first impacted towards the center of two dimers with a fixed orientation. It was found that when Ein was lower than 30 eV, C36 bounces off the surface without breaking up. Increasing Ein to 30-45 eV, bonds were formed between C36 and surface dimer atoms, and the adsorbed C36 retained its original free-cluster structure. Around 50-60 eV, the C36 rebounded from the surface with cage defects. Above 70 eV, fragmentation both in the cluster and on the surface was observed. Our simulation supported the experimental findings that during low-energy cluster beam deposition small fullerenes could keep their original structure after adsorption (i.e. the memory effect), if Ein is within a certain range. Furthermore, we found that the energy threshold for chemisorption is sensitive to the orientation of the incident C36 and its impact position on the asymmetric surface.

Children exposure assessment to ultrafine particles and black carbon: The role of transport and cooking activities

An accurate evaluation of the airborne particle dose-response relationship requires detailed measurements of the actual particle concentration levels that people are exposed to, in every microenvironment in which they reside. The aim of this work was to perform an exposure assessment of children in relation to two different aerosol species: ultrafine particles (UFPs) and black carbon (BC). To this purpose, personal exposure measurements, in terms of UFP and BC concentrations, were performed on 103 children aged 8-11 years (10.1 ± 1.1 years) using hand-held particle counters and aethalometers. Simultaneously, a time-activity diary and a portable GPS were used to determine the children’s daily time-activity pattern and estimate their inhaled dose of UFPs and BC. The median concentration to which the study population was exposed was found to be comparable to the high levels typically detected in urban traffic microenvironments, in terms of both particle number (2.2×104 part. cm-3) and BC (3.8 μg m-3) concentrations. Daily inhaled doses were also found to be relatively high and were equal to 3.35×1011 part. day-1 and 3.92×101 μg day-1 for UFPs and BC, respectively. Cooking and using transportation were recognized as the main activities contributing to overall daily exposure, when normalized according to their corresponding time contribution for UFPs and BC, respectively. Therefore, UFPs and BC could represent tracers of children exposure to particulate pollution from indoor cooking activities and transportation microenvironments, respectively.

Do adolescents ‘like’ the use of social networking and associated technologies for physical activity promotion?

Physical activity has been identified as a key behaviour in determining an individual’s health and functioning. Adolescent physical inactivity has been shown to track strongly through to adulthood. Interventions in youth to promote and increase physical activity have had mixed results. The significant rise over the past decade in time spent by adolescents performing social networking may provide a unique opportunity for health promoters to interact with adolescents through a familiar medium. The purpose of was study is to investigate the potential utility of social networking and associated technologies for the promotion of physical activity amongst adolescents. Participants were recruited from two nondenominational same-sex private schools, from high socioeconomic backgrounds in Brisbane, Australia. A total of 112 (90.3%) participants had complete data sets and were included in the analysis. Account ownership and rates of access to some social networking sites were high. However, a combination of a lack of interest and additional risks associated with social networking utilities, means that caution should be undertaken prior to the commencement of any intervention seeking to increase engagement in physical activities through these mediums. Student smart phone access and interest in smart phone applications for physical activity promotion purposes were moderate, and may provide opportunities for samples of adolescents from high socioeconomic backgrounds who are more likely to have access to appropriate technologies. As technology advances, the rate of smart phone ownership as opposed to overall phone ownership is likely to steadily increase over time. Access and use of information technology by children likely to continue to become more convenient. This makes smart phone applications as a means for physical activity promotion progressively more practical, and a promising future option.

Synthetic reevesite-like material as a visible light photocatalyst for the decontamination of water

A synthetic reevesite-like material has been shown to decolorize selected dyes and degrade phenolic contaminants photocatalytically in water when irradiated with visible light. This material can photoactively decolorize dyes such as bromophenol blue, bromocresol green, bromothymol blue, thymol blue and methyl orange in less than 15 min under visible light radiation in the absence of additional oxidizing agents. Conversely, phenolic compounds suc has phenol, p-chlorophenol and p-nitrophenol are photocat- alytically degraded in approximately 3hwith additional H2O2 when irradiated with visible light. These reactions offer potentially energy effective pathways for the removal of recalcitrant organic waste contaminants.

From rights to responsibilities : reconceptualising carbon sequestration rights in Australia

Biosequestration of carbon in trees, forests and vegetation is a key method for mitigating climate change in Australia. To facilitate this, all States have enacted legislation for carbon sequestration rights, separating commercial rights in carbon from ownership of the land, trees and vegetation in which the carbon is sequestered. Ownership of carbon sequestration rights under state law is a prerequisite for the issue of carbon credits to proponents of ‘eligible sequestration offsets projects’ under the Carbon Credits (Carbon Farming Initiative) Act 2011 (Cth) (‘Carbon Farming Act’). This article examines the extent to which current State carbon sequestration rights support the offsets regime established by the Carbon Farming Act. The Commonwealth Act is concerned with allocating responsibilities to ensure the maintenance of the carbon sequestration, while the State Acts confer commercial rights in the carbon and leave the responsibilities to be allocated by private agreements. The carbon sequestration rights as defined by state laws do not confer the rights of access and management over land that a project proponent needs in order to discharge its responsibilities to maintain the carbon sequestration.

Crime and the commodification of carbon

Carbon will be the world's biggest market. Barclays was the first UK bank to set up a dedicated carbon trading desk to help clients, and Barclays Capital is the most active player in the emissions trading market having traded 300 million tonnes as at February 2007. (Barclays, 2007: 1)

Spin-polarization and ferromagnetism of graphitic carbon nitride materials

Polymeric graphitic carbon nitride materials have attracted increasing attention in recent years owning to their potential applications in energy conversion, environment protection, and so on. Here, from first-principles calculations, we report the electronic structure modification of graphitic carbon nitride (g-C3N4) in response to carbon doping. We showed that each dopant atom can induce a local magnetic moment of 1.0 μB in non-magnetic g-C3N4. At the doping concentration of 1/14, the local magnetic moments of the most stable doping configuration which has the dopant atom at the center of heptazine unit prefer to align in a parallel way leading to long-range ferromagnetic (FM) ordering. When the joint N atom is replaced by C atom, the system favors an antiferromagnetic (AFM) ordering at unstrained state, but can be tuned to ferromagnetism (FM) by applying biaxial tensile strain. More interestingly, the FM state of the strained system is half-metallic with abundant states at the Fermi level in one spin channel and a band gap of 1.82 eV in another spin channel. The Curie temperature (Tc) was also evaluated using a mean-field theory and Monte Carlo simulations within the Ising model. Such tunable electron spin-polarization and ferromagnetism are quite promising for the applications of graphitic carbon nitride in spintronics.

Characterisation of SiO2-supported nickel catalysts for carbon dioxide reforming of methane

The CO2-methane reformation reaction over Ni/SiO2 catalysts has been extensively studied using a range of temperature-programmed techniques and characterisation of the catalysts by thermogravimetry (TG), X-ray diffraction (XRD) and electron microscopy (TEM). The results indicate a strong correlation between the microstructure of the catalyst and its performance. The role of both CO2 and CH4 in the reaction has been investigated and the role of methyl radicals in the reaction mechanism highlighted. A reaction mechanism involving dissociatively adsorbed CO2 and methyl radicals has been proposed.

Carbon dioxide reforming of methane to produce synthesis gas over metal-supported catalysts: State of the art

Carbon dioxide reforming of methane produces synthesis gas with a low hydrogen to carbon monoxide ratio, which is desirable for many industrial synthesis processes. This reaction also has very important environmental implications since both methane and carbon dioxide contribute to the greenhouse effect. Converting these gases into a valuable feedstock may significantly reduce the atmospheric emissions of CO2 and CH4. In this paper, we present a comprehensive review on the thermodynamics, catalyst selection and activity, reaction mechanism, and kinetics of this important reaction. Recently, research has centered on the development of catalysts and the feasible applications of this reaction in industry. Group VIII metals supported on oxides are found to be effective for this reason. However, carbon deposition causing catalyst deactivation is the major problem inhibiting the industrial application of the CO2/CH4 reaction. Ni-based catalysts impregnated on certain supports show carbon-free operation and thus attract much attention. To develop an effective catalyst for CO2 reforming of CH4 and accelerate the commercial application of the reaction, the following are identified to be the most important areas for future work: (1) selection of metal and support and studying the effect of their interaction on catalyst activity; (2) the effect of different promoter on catalyst activity; (3) the reaction mechanism and kinetics; and (4) pilot reactor performance and scale-up operation.

Bond strength of steel hollow sections using carbon fibre reinforced polymer composites

This research was a step forward in developing bond strength of CFRP strengthened steel hollow sections under tension loads. The studies have revealed the ultimate load carrying capacity of the CFRP strengthened steel hollow sections and the stress distribution for different orientations of the CFRP sheet at different layers. This thesis presents a series of experimental and finite element analysis to determine a good understanding of the bond characteristics of CFRP strengthened steel hollow sections.

Fraud risk and the visibility of carbon

In recent years, carbon has been increasingly rendered ‘visible’ both discursively and through political processes that have imbued it with economic value. Greenhouse gas (GHG) emissions have been constructed as social and environmental costs and their reduction or avoidance as social and economic gain. The ‘marketisation’ of carbon, which has been facilitated through various compliance schemes such as the European Union Emissions Trading Scheme (EU ETS), the Kyoto Protocol, the proposed Australian Emissions Reduction Scheme and through the voluntary carbon credit market, have attempted to bring carbon into the ‘foreground’ as an economic liability and/or opportunity. Accompanying the increasing economic visibility of carbon are reports of frauds and scams – the ‘gaming of carbon markets’(Chan 2010). As Lohmann (2010: 21) points out, ‘what are conventionally classed as scams or frauds are an inevitable feature of carbon offset markets, not something that could be eliminated by regulation targeting the specific businesses or state agencies involved’. This paper critiques the disparate discourses of fraud risk in carbon markets and examines cases of fraud within emerging landscapes of green criminology.

Investigation of the [−/A]8 and C1236T genetic variations within the human toll-like receptor 3 gene for association with multiple sclerosis

Multiple sclerosis (MS) is a serious cause of neurological disability among young adults. The clinical course remains difficult to predict, and the pathogenesis of the disease is still modestly understood. Autoimmunity is thought to be a key aspect of the disease, with autoreactive T cells thought to mediate central nervous system (CNS) inflammation to some extent. Toll-like receptors are known to mediate cellular recognition of pathogens by way of patterns of molecular presentation. Toll-like receptor 3 is coded by the gene TLR3 and is recognized as an important factor in virus recognition and is known to be involved in the expression of neuroprotective mediators. We set out to investigate two variations within the TLR3 gene, an 8 bp insertion-deletion \[-/A](8) and a single base-pair variation C1236T, in subjects with MS and matched healthy controls to determine whether significant differences exist in these markers in an Australian population. We used capillary gel electrophoresis and TaqMan genotyping assay techniques to resolve genotypes for each marker, respectively. Our work found no significant difference between frequencies for TLR3 \[-/A](8) by genotype (chi(2)=1.03, p=0.60) or allele (chi(2)=1.09, p=0.30). Similarly, we found no evidence for the association of TLR3 C1236T by genotype (chi(2)=0.35, p=0.84) or allele frequency (chi(2)=0.31, p=0.58). This work reveals no evidence to suggest that these markers are associated with MS in the tested population. Although the role of TLR3 and the wider toll-like receptor family remain significant in neurological and CNS inflammatory disorders, our current work does not support a role for the two tested variants in this gene with regard to MS susceptibility.