Architecture of a biocompatible supramolecular material by supersaturation-driven fabrication of fiber network

The architecture of a biocompatible organogel formed by gelation of a small molecule organic gelator, N-lauroyl-l-glutamic acid di-n-butylamide, in isostearyl alcohol was investigated based on a supersaturation-driven crystallographic mismatch branching mechanism. By controlling the supersaturation of the system, the correlation length that determines the mesh size of the fiber network was finely tuned and the rheological properties of the gel were engineered. This approach is of considerable significance for many gel-based applications, such as controlled release of drugs that requires precise control of the mesh size. A direct cryo-transmission electron microscopy (TEM) imaging technique capable of preserving the network structure was used to visualize its nanostructure.

Microengineering of soft functional materials by controlling the fiber network formation

The engineering of soft functional materials based on the construction of three-dimensional interconnecting self-organized nanofiber networks is reported. The system under investigation is an organogel formed by N-lauroyl-L-glutamic acid di-n-butylamide (GP-1) in propylene glycol. The engineering of soft functional materials is implemented by controlling primary nucleation kinetics of GP-1, which can be achieved by both reducing thermodynamic driving force and/or introducing a tiny amount of specific copolymers (i.e., poly(methyl methacrylate comethacrylic acid)). The primary nucleation rate of GP-1 is correlated to the number density of GP-1 spherulites, which determines the overall rheological properties of soft functional materials. The results show that the presence of a tiny amount of the polymer (0.01-0.06%) can effectively inhibit the nucleation of GP-1 spherulites, which leads to the formation of integrated fiber networks. It follows that with the additive approach, the viscoelasticity of the soft functional material is significantly enhanced (i.e., more than 1.5 times at 40 °C). A combination of the thermal and additive approach led to an improvement of 3.5 times in the viscosity of the gel.

Concentrations of major grass group 5 allergens in pollen grains and atmospheric particles : implications for hay fever and allergic asthma sufferers sensitized to grass pollen allergens

Background

Grass pollen allergens are the most important cause of hay fever and allergic asthma during summer in cool temperate climates. Pollen counts provide a guide to hay fever sufferers. However, grass pollen, because of its size, has a low probability of entering the lower airways to trigger asthma. Yet, grass pollen allergens are known to be associated with atmospheric respirable particles.
Objective

We aimed (1) to determine the concentration of group 5 major allergens in (a) pollen grains of clinically important grass species and (b) atmospheric particles (respirable and nonrespirable) and (2) to compare the atmospheric allergen load with clinical data to assess different risk factors for asthma and hay fever.
Methods

We have performed a continuous 24 h sampling of atmospheric particles greater and lower than 7.2 μm in diameter during the grass pollen season of 1996 and 1997 (17 October 1996–16 January 1997) by means of a high volume cascade impactor at a height of about 15 m above ground in Melbourne. Using Western analysis, we assessed the reactivity of major timothy grass allergen Phl p 5 specific monoclonal antibody (MoAb) against selected pollen extracts. A MoAb-based ELISA was then employed to quantify Phl p 5 and cross-reactive allergens in pollen extracts and atmospheric particles larger and smaller than 7.2 μm.
Results

Phl p 5-specific MoAb detected group 5 allergens in tested grass pollen extracts, indicating that the ELISA employed here determines total group 5 allergen concentrations. On average, 0.05 ng of group 5 allergens were detectable per grass pollen grain. Atmospheric group 5 allergen concentrations in particles > 7.2 μm were significantly correlated with grass pollen counts (rs = 0.842, P < 0.001). On dry days, 37% of the total group 5 allergen load, whereas upon rainfall, 57% of the total load was detected in respirable particles. After rainfall, the number of starch granule equivalents increased up to 10-fold; starch granule equivalent is defined as a hypothetical potential number of airborne starch granules based on known pollen count data. This indicates that rainfall tended to wash out large particles and contributed to an increase in respirable particles containing group 5 allergens by bursting of pollen grains. Four day running means of group 5 allergens in respirable particles and of asthma attendances (delayed by 2 days) were shown to be significantly correlated (P < 0.001).
Conclusion

Here we present, for the first time, an estimation of the total group 5 allergen content in respirable and nonrespirable particles in the atmosphere of Melbourne. These results highlight the different environmental risk factors for hay fever and allergic asthma in patients, as on days of rainfall following high grass pollen count, the risk for asthma sufferers is far greater than on days of high pollen count with no associated rainfall. Moreover, rainfall may also contribute to the release of allergens from fungal spores and, along with the release of free allergen molecules from pollen grains, may be able to interact with other particles such as pollutants (i.e. diesel exhaust carbon particles) to trigger allergic asthma.

How potent is fiscal policy in Australia?

This article examines the efficacy of fiscal policy in Australia, focusing on the relationship between changes in the economy’s consolidated fiscal imbalance and private sector saving over recent decades. We first examine the macroeconomic significance of the offset coefficient between public and private savings, whose size effectively determines the effectiveness of fiscal activism. The approach innovatively suggests that these estimates simultaneously reflect Ricardian and other non-Keynesian explanations of private consumption, such as the lifecycle and permanent income theories. Econometric estimation of the offset coefficient for Australia over the period 1980–2008 yields values between 0.75 and near unity, which imply a small or near-zero fiscal multiplier, and that running budget surpluses to lift national saving is ineffective.

Backward modelling and look-ahead fuzzy energy management controller for a parallel hybrid vehicle

This paper focuses on a parallel hybrid electric vehicle. It first develops a model for the vehicle using the backward-looking approach where the flow of energy starts from wheels and spreads towards engine and electric motor. Next, a fuzzy logic-based strategy is developed to control the operation of the vehicle. The objectives of the controller include managing the energy flow from engine and electric motor, controlling transmission ratio, adjusting speed, and sustaining battery's state of charge. The controller examines current vehicle speed, demand torque, slope difference, state of charge of battery, and engine and electric motor rotation speeds. Then, it determines the best values for continuous variable transmission ratio, speed, and torque. A slope window scheme is also developed to take into account the look-ahead slope information and determine the best vehicle speed for better fuel economy. The developed model and control strategy are simulated. The simulation results are presented and discussed. It is shown that the use of the proposed fuzzy controller reduces fuel consumption.

Measurement of surface forces between mica sheets immersed in aqueous quaternary ammonium ion solutions

Forces between mica surfaces immersed in Me4NBr, Pr4NBr, and Pe4NBr solutions over a wide concentration range are reported (Me = methyl, Pr = propyl, Pe = pentyl). In each case the cation adsorbs quite strongly onto the negatively charged mica surface and determines the double-layer potential. However, this strong adsorption does not cause complete neutralization of the negative lattice charge apparently because of packing constraints due to the large size of these ions. Adsorption of Me4N+ ions gives rise to a short-range (<2 nm) repulsive force similar to that previously observed between bilayers of CTAB and may be due to the residual hydration of these ions. The large rations also, unexpectedly, give rise to short-range repulsive forces but of a somewhat different nature. In this case, the repulsive forces can be explained by assuming that the large adsorbed ions shift the plane of charge a distance of one ion diameter from the mica surface. At all but very high concentrations these larger ions could be displaced from the mica surfaces on forcing them together. No evidence of any “hydrophobic attraction” was observed between surfaces containing these adsorbed ions. Previous studies on coagulation are discussed in the light of our results.

Hydrogen bonded block copolymer systems : from microphase separation in solid state to self-assembly in aqueous solutions

Block copolymer systems with hydrogen bonding interactions have received relatively little attention. Recently, we have investigated the self-assembly and phase separation in such block copolymer systems with an attempt to elucidate the role of hydrogen bonding interactions both theoretically and experimentally [1-4]. In A-b-B/C diblock copolymer/homopolymer systems, the phase behavior was theoretically analyzed according to the random phase approximation and correlated with hydrogen bonding interactions in terms of the difference in inter-association constants (K). To examine how the hydrogen bonding determines the self-assembly and morphological transitions in these systems, we have introduced the K values as a new variable into the phase diagram which we established for the first time (Fig. 1). Multiple vesicular morphologies were formed in aqueous solution of A-b-B/A-b-C diblock copolymer complexes of PS-b-PAA and PS-b-PEO. Interconnected compound vesicles (ICCVs) were observed for the first time as a new morphology (Fig. 2), along with other aggregated nanostructures including vesicles, multilamellar vesicles, thick-walled vesicles and irregular aggregates. Complexation of two amphiphilic diblock copolymers provides a viable approach to vesicles in aqueous media.

Improving the dispersion and mechanical properties of epoxy/carbon nanotube composites

The incorporation and uniform dispersion of carbon nanotubes (CNTs) in polymer matrix could facilitate engineers to create high performance nanocomposites that potentially compete with most advanced materials in nature. The unique combination of outstanding mechanical, thermal, and electrical properties of CNTs makes them excellent nanofillers for the fabrication of advanced materials. Successful enhancement in mechanical properties via reinforcement is expected only when the nanofillers are well dispersed in the polymer matrix. Moreover, the orientation as well as the CNT/matrix interfacial strength also determines the effective physical properties of the nanocomposites. However, CNTs typically assemble to give bundles, which are heavily entangled to each other with a high aspect ratio and a large π-electronic surface. In this work, we outline some preliminary results in preparing high performance epoxy composites. Composites with fine dispersion and superior mechanical properties were prepared using epoxy and multiwalled carbon nanotubes (MWCNTs). The fine dispersion of the nanocomposites can be identified in the high resolution SEM image shown in Figure 1. This method can provide an alternative route for the preparation of new structural and functional nanocomposites.

Look-ahead intelligent energy management of a parallel hybrid electric vehicle

Improving fuel efficiency in vehicles can reduce the energy consumption concerns associated with operating the vehicles. This paper presents a model for a parallel hybrid electric vehicle. In the model, the flow of energy starts from wheels and spreads toward engine and electric motor. A fuzzy logic based control strategy is implemented for the vehicle. The controller manages the energy flow from the engine and the electric motor, controlling transmission ratio, adjusting speed, and sustaining battery's state of charge. The controller examines the vehicle speed, demand torque, slope difference, state of charge of battery, and engine and electric motor rotation speeds. It then determines the best values for continuous variable transmission ratio, speed, and torque. A slope window method is formed that takes into account the look-ahead slope information, and determines the best vehicle speed. The developed model and control strategy are simulated using real highway data relating to Nowra-Bateman Bay in Australia, and SAE Highway Fuel Economy Driving Schedule. The simulation results are presented and discussed. It is shown that the use of the proposed fuzzy controller reduces the fuel consumption of the vehicle.

Engaging and effective asynchronous online discussion forums

Discussion is usually considered a powerful tool for the development of pedagogical skills such as critical thinking, collaboration and reflection. In the last few years, an online asynchronous discussion forum has become an integral part of teaching and learning in tertiary education. However, there are considerable challenges involved in designing discussion forum for learning and teaching arrangements that can support desired learning outcomes. The study analysed the factors that affect the level of the student participation in the online discussion forums with emphases on some of the critical issues that should be taken into account when designing online discussions forums that can support desired learning outcomes. We show that the course instructor roles and level of participations in the discussion forum particularly determines the overall level of discussion among the learning communities.

Antibacterial activity of stevioside towards food-borne pathogenic bacteria

This study determines the inhibitory effect of Stevia rebaudiana leaf extracts and its purified bioactive compound ‘stevioside’ against food-related pathogens. The S. rebaudiana solvent extracts (1000 μg/mL) displayed antibacterial activity to Serratia marcescens, Klebsiella pneumoniae, Bacillus cereus, Pseudomonas aeruginosa, B. subtilis, Alcaligenes denitrificans and Salmonella typhimurium. Of the six solvents, ethanol and acetone extracts displayed the highest zone of inhibition. The bioactive compound from S. rebaudiana was purified by solvent extraction, thin-layer chromatography followed by structural characterization by spectroscopy evidence. Purified stevioside prevented the growth of tested bacterial species, i.e. B. subtilis, K. pneumoniae and S. typhimurium. Significant zone of inhibition (12 mm) was observed against B. cereus which proposes potential application of stevioside in foods to increase their shelf life.

Learning about dynamic scenes

Incremental learning allows modification of developed concepts without the need for prior knowledge of all data. An incremental algorithm is developed to focus on the problems of memory size, forgetting and concept drift. The evidence based forgetting procedure minimizes the concept size and maintains its consistency with respect to the incoming data. An age value associated with the data determines its reinforcement or removal from a concept.

The impact of client attitudes on the selection of contractors

This research is concerned with identifying prequalification criteria that both clients and contractors believe are good indicators of future construction performance. Criteria used in the past have been developed by clients in a largely idiosyncratic manner with little or no consultation with the contractors affected. The methodology chosen for the research was a survey which probed stakeholder attitudes to commonly used prequalification criteria. This was carried out via a postal questionnaire involving contactors and clients across Australia. The data was analysed using Discriminant Analysis, which is a multivariate statistical approach that determines the differences between groups. The research is structured around 39 criteria that were developed as part of a whole-of–government task force into best practice in procurement. The findings identified the most important criteria from both a client’s perspective, and a contractor’s perspective. The purpose was to discover if those differences reduce the effectiveness of the procurement process. This paper contributes to a more clarified understanding of the impact or contrasting views between the stakeholders involved in the prequalification process. This work is innovative because it is one of a few pieces of research that showed that clients and contractors do actually have divergent opinions on the importance of some criteria currently relied upon in the decision making process. The most important prequalification criteria are identified and possible reasons for these differences are discussed.

Hierarchical representation for spatial knowledge

One of the fundamental issues in building autonomous agents is to be able to sense, represent and react to the world. Some of the earlier work [Mor83, Elf90, AyF89] has aimed towards a reconstructionist approach, where a number of sensors are used to obtain input that is used to construct a model of the world that mirrors the real world. Sensing and sensor fusion was thus an important aspect of such work. Such approaches have had limited success, and some of the main problems were the issues of uncertainty arising from sensor error and errors that accumulated in metric, quantitative models. Recent research has therefore looked at different ways of examining the problems. Instead of attempting to get the most accurate and correct model of the world, these approaches look at qualitative models to represent the world, which maintain relative and significant aspects of the environment rather than all aspects of the world. The relevant aspects of the world that are retained are determined by the task at hand which in turn determines how to sense. That is, task directed or purposive sensing is used to build a qualitative model of the world, which though inaccurate and incomplete is sufficient to solve the problem at hand. This paper examines the issues of building up a hierarchical knowledge representation of the environment with limited sensor input that can be actively acquired by an agent capable of interacting with the environment. Different tasks require different aspects of the environment to be abstracted out. For example, low level tasks such as navigation require aspects of the environment that are related to layout and obstacle placement. For the agent to be able to reposition itself in an environment, significant features of spatial situations and their relative placement need to be kept. For the agent to reason about objects in space, for example to determine the position of one object relative to another, the representation needs to retain information on relative locations of start and finish of the objects, that is endpoints of objects on a grid. For the agent to be able to do high level planning, the agent may need only the relative position of the starting point and destination, and not the low level details of endpoints, visual clues and so on. This indicates that a hierarchical approach would be suitable, such that each level in the hierarchy is at a different level of abstraction, and thus suitable for a different task. At the lowest level, the representation contains low level details of agent's motion and visual clues to allow the agent to navigate and reposition itself. At the next level of abstraction the aspects of the representation allow the agent to perform spatial reasoning, and finally the highest level of abstraction in the representation can be used by the agent for high level planning.

Characteristics of participants in Australia's Get Healthy telephone-based lifestyle information and coaching service : reaching disadvantaged communities and those most at need

To address increasing rates of overweight and obesity, a population-based telephone intervention was introduced in New South Wales, Australia. The Get Healthy Information and Coaching Service® (GHS) offered participants a 6-month coaching program or detailed self-help information. Determining the population reach of GHS is of public health importance to ensure that the program reaches disadvantaged groups. This paper describes the socio-demographic and risk profile of participants (n = 4828) in the first 18 months of operations, determines how representative they are of the population, assesses changes in participants’ socio-demographic profile and compares ‘information-only’ and ‘coaching’ participants. The results show that GHS users are representative of the adult population in relation to education, employment status, Aboriginal status, fruit and vegetable consumption and alcohol use. However, more female, middle-aged, English-speaking, rural and socially disadvantaged adults participated in GHS. Coaching Participants were more likely to be overweight and to be ex-smokers than the general population. There was substantial variability in GHS recruitment, when mass-reach television advertising was used, participants enrolled from a major city and from more disadvantaged communities. The GHS has broader population reach than many local interventions, but further efforts are needed to increase reach by Aboriginal communities, other minorities and men.