Analysis of organic aerosols collected on filters by Aerosol Mass Spectrometry for source identification

Aerosol mass spectrometers (AMS) are powerful tools in the analysis of the chemical composition of airborne particles, particularly organic aerosols which are gaining increasing attention. However, the advantages of AMS in providing on-line data can be outweighed by the difficulties involved in its use in field measurements at multiple sites. In contrast to the on-line measurement by AMS, a method which involves sample collection on filters followed by subsequent analysis by AMS could significantly broaden the scope of AMS application. We report the application of such an approach to field studies at multiple sites. An AMS was deployed at 5 urban schools to determine the sources of the organic aerosols at the schools directly. PM1 aerosols were also collected on filters at these and 20 other urban schools. The filters were extracted with water and the extract run through a nebulizer to generate the aerosols, which were analysed by an AMS. The mass spectra from the samples collected on filters at the 5 schools were found to have excellent correlations with those obtained directly by AMS, with r2 ranging from 0.89 to 0.98. Filter recoveries varied between the schools from 40 -115%, possibly indicating that this method provides qualitative rather than quantitative information. The stability of the organic aerosols on Teflon filters was demonstrated by analysing samples stored for up to two years. Application of the procedure to the remaining 20 schools showed that secondary organic aerosols were the main source of aerosols at the majority of the schools. Overall, this procedure provides accurate representation of the mass spectra of ambient organic aerosols and could facilitate rapid data acquisition at multiple sites where AMS could not be deployed for logistical reasons.

Endotoxins in indoor air and settled dust in primary schools in a subtropical climate

Endotoxins can significantly affect the air quality in school environments. However, there is currently no reliable method for the measurement of endotoxins and there is a lack of reference values for endotoxin concentrations to aid in the interpretation of measurement results in school settings. We benchmarked the “baseline” range of endotoxin concentration in indoor air, together with endotoxin load in floor dust, and evaluated the correlation between endotoxin levels in indoor air and settled dust, as well as the effects of temperature and humidity on these levels in subtropical school settings. Bayesian hierarchical modeling indicated that the concentration in indoor air and the load in floor dust were generally (<95th percentile) < 13 EU/m3 and < 24,570 EU/m2, respectively. Exceeding these levels would indicate abnormal sources of endotoxins in the school environment, and the need for further investigation. Metaregression indicated no relationship between endotoxin concentration and load, which points to the necessity for measuring endotoxin levels in both the air and settled dust. Temperature increases were associated with lower concentrations in indoor air and higher loads in floor dust. Higher levels of humidity may be associated with lower airborne endotoxin concentrations.

NSAM-derived total surface area vs. SMPS-derived "mobility equivalent" surface area for different environmentally relevant aerosols

The surface area of inhaled particles deposited in the alveolar region, as reported by the TSI nanoparticle surface area monitor (NSAM), was compared with the corresponding value estimated by a TSI scanning mobility particle sizer (SMPS) for a range of environmentally relevant aerosols, including petrol emissions, ETS, laser printer emissions, cooking emissions and ambient aerosols. The SMPS values were based on a mobility size distribution assuming spherical particles using the appropriate size-dependent alveolar-deposition factors provided by the ICRP. In most cases, the two instruments showed good linear agreement. With petrol emissions and ETS, the linearity extended to over 103 μm2 cm-3. With printer emissions, there was good linearity up to about 300 μm2 cm-3 while the NSAM increasingly overestimated the surface area at higher concentrations. The presence of a nucleation event in ambient air caused the NSAM to over-estimate the surface area by a factor of 2. We summarize these results and conclude that the maximum number concentration up to which the NSAM is accurate clearly depends on the type of aerosol being sampled and provide guidance for the use of the instrument.

First measurements of source apportionment of organic aerosols in the Southern Hemisphere

An Aerodyne Aerosol Mass Spectrometer was deployed at five urban schools to examine spatial and temporal variability of organic aerosols (OA) and positive matrix factorization (PMF) used for the first time in the Southern Hemisphere to apportion the sources of the OA across an urban area. The sources identified included hydrocarbon-like OA (HOA), biomass burning OA (BBOA) and oxygenated OA (OOA). At all sites, the main source was OOA, which accounted for 62–73% of the total OA mass and was generally more oxidized compared to those reported in the Northern Hemisphere. This suggests that there are differences in aging processes or regional sources in the two hemispheres. Unlike HOA and BBOA, OOA demonstrated instructive temporal variations but not spatial variation across the urban area. Application of cluster analysis to the PMF-derived sources offered a simple and effective method for qualitative comparison of PMF sources that can be used in other studies.

Alveolar dose of ultrafine particles for children in urban environments

The aim of this study was to quantify school children’s exposure to ultrafine particles (UFP) in urban environments. The study was conducted as part of a larger epidemiological project aiming to determine the association between exposures to UFPs and children’s health, titled “Ultrafine Particles from Traffic Emissions and Children’s Health”1 (UPTECH). School children aged 8-11 years old at 24 state schools within the Brisbane Metropolitan Area participated in the present study. This paper presents the methodology and results for calculating deposited UFP surface area in the alveolar region (dose), where UFP deposition is more efficient for particles larger than 6 nm...

A portrayal of new entrants into the Australian economy (Entrepreneurial individuals and ventures)

This paper provides a descriptive overview of the venture creation in Australia, those who participate in it and the types of firms they build. Findings of interest in this paper include: • The majority of business founders (89 per cent) state the motivation to start a new business is opportunity-driven rather than necessity driven. • The extent of under-representation of women business founders in Australia appears to be lower than international comparisons and has decreased over time. • Australian business founders tend to possess significant ‘human capital’ many are university-educated, and large shares have different types of experience that may benefit the start-up. • The major industries for start-up activities are Retailing; various service industries (Business Consulting; Health, Education and Social; other Consumer services); Construction, Manufacturing, and Agriculture. • A large proportion of CAUSEE respondents (49 per cent nascent firms and 46 per cent young firms) are members of start-up teams, which is similar to international comparisons.

Illustrating outcomes for Australian nascent and young firm entrepreneurial activity

This paper examines the outcomes of nascent and young entrepreneurial firms in Australia. Findings of interest in this paper include: • After three years similar proportions of nascent firms reach an operational state (31 per cent), i.e. sales regularly exceed costs, compared with those that have terminated (35 per cent), and those who are still trying to achieve venture creation (34 per cent). This outcome closely mirrors the outcomes in the US PSED study. • The young firm sample shows that these new ventures remain more robust to firm closure. The vast majority of young firms (78 per cent) continue to be active in the market the last time they participated in CAUSEE. • The annual termination rate for young firms is 9 per cent at most, and 14 per cent cumulatively, while cumulatively only 8 per cent of young firms experience a drop-off in activity to be considered as having uncertain status. • The average number of employees in Nascent Firms is one person, the average number of Young Firm employees increases from two at first sampling to three after three years. • While the founders of exiting Nascent Firms are more likely to return to their old job upon termination of their business, Young Firm founders move on to new jobs. Regardless the majority of exiting firm founders rate their experience as positive and are prepared to attempt business creation in the future.

Innovation and change in new ventures

This paper examines the innovativeness of nascent and young entrepreneurial firms in Australia. Findings of interest in this paper include: • The vast majority of new ventures offer some degree of innovation in some aspect of their business, be it the product, the process, their market selection or their marketing approach. • With close to 75 per cent claiming they do more than taking mere imitations to the market, novelty in the product/service is the type of innovation most commonly offered by start-up firms. • The innovativeness of start-ups varies by industry. Construction start-ups stand out as particularly low in innovation across all indicators, while Manufacturing stands out the most in the positive direction. • Team start-ups other than spouse teams have higher novelty, as do ventures started by founders with prior start-up experience. • There is no association between the founders’ level of education and the novelty of the ventures they (try to) create.

What it means to be green : an examination of early stage environmental and sustainability focused firms

This paper examines ‘green’ entrepreneurial nascent and young firms in Australia. Findings of interest in this paper include: • Green entrepreneurs are more likely to be highly educated and have an extended depth of experience within their industry and are more likely to have started a business prior to their current venture. • Green entrepreneurs exhibit increased levels of innovation, with an increased focus on new & high technology, R&D and the development of proprietary technology. • Green entrepreneurs are most likely to be based upon a product rather than a service and have a higher emphasis upon growth when compared with non-green entrepreneurs. • Green entrepreneurial firms tend to have a longer venture creation process and draw financial resources from a larger number of sources and rely more upon equity as a means of financing their venture.

New venture internationalisation

This paper investigates the international background and international activities of Australian start-up firms. Findings of interest in this paper include: • Due to their small scale, young age and distant location firm founders then to favour the domestic market rather that engage internationally. • Firms that do engage internationally tend to do so at the very early stages of venture creation. • Firms that do engage in exporting activities tend to rely on intermediaries rather than more direct forms of export actions.

Capturing gazelles : features of high potential firms and new venture growth

This paper investigates the characteristics of ventures which have the potential to reach high growth and compares this with ‘everyday’ new ventures. Findings of interest in this paper include: • HP firms are characterised by higher human capital, are more likely to have a team of founders, are more likely to be product based. • HP firms are more likely to achieve more extreme levels of growth (both positive and negative). • HP ventures that make a loss are more likely to do so early in the venture process. Those that do hold on show that there can higher levels of loss made later on in firm development. HP firms have higher resource needs, in terms of seeking external finance, but are no more likely to receive external finance than regular firms.

Unpacking the venture creation process

This paper investigates the dimensions of time and effort and how these factors impact on the venture creation process in Australia. Findings of interest in this paper include: • First and foremost business planning is used as a thinking tool within the boundaries of the firm. • Business planning is more strongly associated with firms that are more ambitious, being built by teams, draw on more experience or education. • Industry characteristics in part drive the duration required for venture creation. Manufacturing and Agriculture based firms seemingly take longer timeframes than other industries. Extended venture creation times frames are also associated with firms that aim to bring more novel concepts to market.

Identifying important success factors in new venture creation

This paper seeks to uncover the factors that lead to a successful entrepreneurial experience and or venture. Findings of interest in this paper include: • A venture’s initial aspirations are a double edged sword. Ambition may lead to improved performance by striving to reach harder goals. Harder goals are more difficult therefore this may lead to some dissatisfaction, and possibly abandonment of the venture. • Venture legitimacy is important to establish where possible. Firms that formalize their legal form are more successful, as are those set up a shop-front in order to makes sales. • Increased use of technology and higher levels of novelty does not guarantee success early on. Firms of this nature have longer processes, and attempting to create brand new markets is difficult to achieve. At the same time developing your own technology and securing this intellectual property is important for success. • Having goals to work towards and business planning may be useful, but only if the plan is actively revised. Just having a business plan does not matter. Business plans are more useful as a thinking tool than as a blueprint for action. It is the process of thinking through while reviewing the plan that provides the benefit, not following its instruction to the letter.

Preferential invasion by Plasmodium merozoites and the self-regulation of parasite burden

The preferential invasion of particular red blood cell (RBC) age classes may offer a mechanism by which certain species of Plasmodia regulate their population growth. Asexual reproduction of the parasite within RBCs exponentially increases the number of circulating parasites; limiting this explosion in parasite density may be key to providing sufficient time for the parasite to reproduce, and for the host to develop a specific immune response. It is critical that the role of preferential invasion in infection is properly understood to model the within-host dynamics of different Plasmodia species. We develop a simulation model to show that limiting the range of RBC age classes available for invasion is a credible mechanism for restricting parasite density, one which is equally as important as the maximum parasite replication rate and the duration of the erythrocytic cycle. Different species of Plasmodia that regularly infect humans exhibit different preferences for RBC invasion, with all species except P. falciparum appearing to exhibit a combination of characteristics which are able to selfregulate parasite density.

Graphene-based thin film supercapacitor with graphene oxide as dielectric spacer

Thin film supercapacitors are produced by using electrochemically exfoliated graphene (G) and wet-chemically produced graphene oxide (GO). Either G/GO/G stacked film or sole GO film are sandwiched by two Au films to make devices, where GO is the dielectric spacer. The addition of graphene film for charge storage can increase the capacitance about two times, compared to the simple Au electrode. It is found that the GO film has very high dielectric constant, accounting for the high capacitance of these devices. AC measurements reveal that the relative permittivity of GO is in the order of 104 within the frequency range of 0.1–70 Hz.