Investigation on mechanical behaviour of AM60 magnesium alloys

Purpose: In this work, tension, impact, bend and fatigue tests were conducted in an AM60 magnesium alloy. The effects of environmental temperature and loading rates on impact and tension behavior of the alloy were also investigated. Design/methodology/approach: The tests were conducted using an Instron universal testing machine. The loading speed was changed from 1 mm/min to 300 mm/min to gain a better understanding of the effect of strain rate. To understand the failure behavior of this alloy at different environmental temperatures, Charpy impact test was conducted in a range of temperatures (-40~35°C). Plane strain fracture toughness (KIC) was evaluated using compact tension (CT) specimen. To gain a better understanding of the failure mechanisms, all fracture surfaces were observed using scanning electron microscopy (SEM). In addition, fatigue behavior of this alloy was estimated using tension test under tension-tension condition at 30 Hz. The stress amplitude was selected in the range of 20~50 MPa to obtain the S-N curve. Findings: The tensile test indicated that the mechanical properties were not sensitive to the strain rates applied (3.3x10-4~0.1) and the plastic deformation was dominated by twining mediated slip. The impact energy is not sensitive to the environmental temperature. The plane strain fracture toughness and fatigue limit were evaluated and the average values were 7.6 MPa.m1/2 and 25 MPa, respectively. Practical implications: Tested materials AM60 Mg alloy can be applied among others in automotive industry aerospace, communication and computer industry. Originality/value: Many investigations have been conducted to develop new Mg alloys with improved stiffness and ductility. On the other hand, relatively less attention has been paid to the failure mechanisms of Mg alloys, such as brittle fracture and fatigue, subjected to different environmental or loading conditions. In this work, tension, impact, bend and fatigue tests were conducted in an AM60 magnesium alloy.

Impact of a change in tillage and crop residue management practice on soil chemical and microbiological properties in a cereal-producing red duplex soil in NSW, Australia

The effect of a change of tillage and crop residue management practice on the chemical and micro-biological properties of a cereal-producing red duplex soil was investigated by superimposing each of three management practices (CC: conventional cultivation, stubble burnt, crop conventionally sown; DD: direct-drilling, stubble retained, no cultivation, crop direct-drilled; SI: stubble incorporated with a single cultivation, crop conventionally sown), for a 3-year period on plots previously managed with each of the same three practices for 14 years. A change from DD to CC or SI practice resulted in a significant decline, in the top 0-5 cm of soil, in organic C, total N, electrical conductivity, NH4-N, NO3-N, soil moisture holding capacity, microbial biomass and CO2 respiration as well as a decline in the microbial quotient (the ratio of microbial biomass C to organic C; P <0.05). In contrast, a change from SI to DD or CC practice or a change from CC to DD or SI practice had only negligible impact on soil chemical properties (P >0.05). However, there was a significant increase in microbial biomass and the microbial quotient in the top 0-5 cm of soil following the change from CC to DD or SI practice and with the change from SI to DD practice (P <0.05). Analysis of ester-linked fatty acid methyl esters (EL-FAMEs) extracted from the 0- to 5-cm and 5- to 10-cm layers of the soils of the various treatments detected changes in the FAME profiles following a change in tillage practice. A change from DD practice to SI or CC practice was associated with a significant decline in the ratio of fungal to bacterial fatty acids in the 0- to 5-cm soil (P <0.05). The results show that a change in tillage practice, particularly the cultivation of a previously minimum-tilled (direct-drilled) soil, will result in significant changes in soil chemical and microbiological properties within a 3-year period. They also show that soil microbiological properties are sensitive indicators of a change in tillage practice.

The impact of property title type on residential property returns

Residential property in New Zealand comprises both freestanding residential properties and medium to high density residential properties. Medium to high density residential property comprises the typical units, townhouses and semi-detached houses common in most residential property markets. However, in many of the larger cities of New Zealand the free standing residential property market has evolved into two separate markets being freehold residential property and cross lease residential property. Cross leases have developed as a form of infill housing to reduce the urban sprawl in major canters, while reducing the time and cost for residential property developers. A cross lease is created when an existing freestanding residential property subdivides a portion of the existing land for the erection of another house on the original title, basically dividing one larger residential section into two smaller residential blocks. This paper will analyse house prices in Christchurch over the period 1992 to 2006 to determine if the various housing markets have shown similar capital returns or if there is a specific preference for a particular residential property title.

The impact of flooding on residential property values in England

Severe flooding throughout England in Autumn 1998 and 2000, has seen an increase in the extent of flood liable residential areas throughout England, as well as an increase in the actual levels of flood damage in all previously recognised flood prone residential areas. The increasing cost of rectifying the damage caused to residential properties from flooding has been of some concern to the residential property valuation profession and sales and leasing agency practices. However, the increasing trend in the frequency of flooding in England, combined with an increase in severity of flooding is now causing some degree of concern in the residential insurance and housing finance sectors. In order to determine and quantify the impact of flooding and flood damage on the residential property market in England, a survey of Chartered Surveyors and Chartered Real Estate Valuers has been carried out across the main flood affected counties of England. This survey will provide similar details to the research completed by Eves (1999, 2001) and Fibbens (1993) in relation to residential property flooding in Australia. This survey provides comprehensive responses in relation to the degree of flood affectation across counties, the effect of flooding on residential property values, the impact of flooding on building insurance premiums and possible difficulties in obtaining finance to purchase residential property in recognised flood areas.

Determinants and market impact of seasoned equity offerings : the case of A-REITs

The paper examines the decision by Australian Real Estate Trusts (A-REITs) to issue seasoned equity offerings from 2000 - 2008 and stock market reaction to the offerings. The findings reveal that highly leveraged A-REITs with variable earnings are less likely to issue seasoned equity offerings. Inconsistent results for structure and type of properties held by the A-REIT do not allow for inference to be drawn. Similar to previous studies of seasoned equity offerings, we find a significant negative abnormal return associated with their announcement and no evidence of excessive leakage of information. Furthermore, market reaction differences to announcements of SEOs for the pre-global financial crisis (GFC) (2000-2006) and GFC eras (2007-2008) are noted with GFC era shareholders incurring larger abnormal return losses at 1.13% in comparison to the pre-GFC era shareholder loss of 0.34% on the SEO announcement day. Cross-sectional regressions show that the issued amount, leverage and profitability are significant factors affecting abnormal returns. Growth opportunities, tangibility, operating risk, size of A-REIT and other variables capturing A-REIT structure and property types held do not have an impact on abnormal returns

Legislative change will impact on conveyancing

One of the more significant conveyancing decisions of 2005 was MNM Developments Pty Ltd v Gerrard [2005] QCA 230 (‘Gerrard’). Real estate agents, in particular, became concerned when the Court of Appeal raised grave doubts concerning the validity of a contract for the sale of residential property formed by the use of fax. As a result, the government acted quickly to introduce amendments to the Property Agents and Motor Dealers Act 2000 (Qld) (‘PAMDA’) and the Body Corporate and Community Management Act 1997 (Qld) (‘BCCMA’). The relevant Act is the Liquor and Other Acts Amendment Act 2005 (Qld). These amendments commenced on 1 December 2005. In the second reading speech, the Minister stated that these amendments would provide certainty for sellers of residential properties or their agents when transmitting pre-contractual documents by facsimile and other electronic means. The accuracy of this prediction must be assessed in light of the errors that may occur.

Dangers of the after-dark wonderlands : Part A - A review of the impact of physical environment design on nightclub violence

Nightclubs are businesses. Their business is pleasure; however pleasure has its price. People have become increasingly concerned about the problems of violence in society but why do higher levels of violence occur in nightclubs despite the established patterns of behaviour that dictates how we socialise and act? In response, researchers have focused on identifying social and situational factors that may contribute to violence from a government perspective, focusing on a variety of specific issues ranging from financial standpoints with effective target marketing strategies to legal obligations of supplying alcohol and abiding regulatory conditions. There is little research into specific design properties that can determine design standards to ensure/improve the physical design of nightclub environments to reduce patron violence. To address this gap, this current article aims to understand how people experience and respond to the physical environment of nightclubs and how these spaces influence their behaviour. The first section of this paper examines the background on nightclubs and theories concerning the influence of pleasure. The second section of this paper details the findings of existing studies that have examined the nightlife context and the various factors that influence patron violence. The main finding of this paper is that although alcohol likely plays a contributing role in aggressive patron behaviour, there is evidence that the relationship is moderated by a number of significant factors relating to the characteristics of the drinking environment such as: physical comfort; the degree of overall 'permissiveness‘ in the establishment; crowding; and physical environmental elements most influenced by day to-day management practices such as lighting, ventilation, cleanliness and seating arrangements. The findings from this paper have been used to develop a framework to guide exploratory research on how specific elements of the physical environment of nightclubs have an impact on elevated patron aggression and assault (Koleczko & Garcia Hansen, 2011).

Dangers of the after-dark wonderlands : Part B - A review of the impact of the physical environment design on nightclub violence

Violence in nightclubs is a serious problem that has the Australian government launching multimillion dollar drinking campaigns. Research on nightclub violence has focused on identifying contributing social and environmental factors, with many concentrating on a variety of specific issues ranging from financial standpoints with effective target marketing strategies to legal obligations of supplying alcohol and abiding regulatory conditions. Moreover, existing research suggests that there is no single factor that directly affects the rate violence in licensed venues. As detailed in the review paper of Koleczko and Garcia Hansen (2011), there is little research about the physical environment of nightclubs and which specific design properties can be used to determine design standards to ensure/improve the physical design of nightclub environments to reduce patron violence. This current study seeks to address this omission by reporting on a series of interviews with participants from management and design domains. Featured case studies are both located in Fortitude Valley, a Mecca for party-goers and the busiest nightclub district in Queensland. The results and analysis support the conclusions that a number of elements of the physical environment influence elevated patron aggression and assault.

The impact of nonlinear exposure risk relationships on seasonal time series data: modelling danish neonatal birth anthropometric data

Background Birth weight and length have seasonal fluctuations. Previous analyses of birth weight by latitude effects identified seemingly contradictory results, showing both 6 and 12 monthly periodicities in weight. The aims of this paper are twofold: (a) to explore seasonal patterns in a large, Danish Medical Birth Register, and (b) to explore models based on seasonal exposures and a non-linear exposure-risk relationship. Methods Birth weight and birth lengths on over 1.5 million Danish singleton, live births were examined for seasonality. We modelled seasonal patterns based on linear, U- and J-shaped exposure-risk relationships. We then added an extra layer of complexity by modelling weighted population-based exposure patterns. Results The Danish data showed clear seasonal fluctuations for both birth weight and birth length. A bimodal model best fits the data, however the amplitude of the 6 and 12 month peaks changed over time. In the modelling exercises, U- and J-shaped exposure-risk relationships generate time series with both 6 and 12 month periodicities. Changing the weightings of the population exposure risks result in unexpected properties. A J-shaped exposure-risk relationship with a diminishing population exposure over time fitted the observed seasonal pattern in the Danish birth weight data. Conclusion In keeping with many other studies, Danish birth anthropometric data show complex and shifting seasonal patterns. We speculate that annual periodicities with non-linear exposure-risk models may underlie these findings. Understanding the nature of seasonal fluctuations can help generate candidate exposures.

Properties of lignin and poly(hydroxybutyrate) blends

The Queensland University of Technology (QUT) allows the presentation of a thesis for the Degree of Doctor of Philosophy in the format of published or submitted papers, where such papers have been published, accepted or submitted during the period of candidature. This thesis is composed of Seven published/submitted papers and one poster presentation, of which five have been published and the other two are under review. This project is financially supported by the QUTPRA Grant. The twenty-first century started with the resurrection of lignocellulosic biomass as a potential substitute for petrochemicals. Petrochemicals, which enjoyed the sustainable economic growth during the past century, have begun to reach or have reached their peak. The world energy situation is complicated by political uncertainty and by the environmental impact associated with petrochemical import and usage. In particular, greenhouse gasses and toxic emissions produced by petrochemicals have been implicated as a significant cause of climate changes. Lignocellulosic biomass (e.g. sugarcane biomass and bagasse), which potentially enjoys a more abundant, widely distributed, and cost-effective resource base, can play an indispensible role in the paradigm transition from fossil-based to carbohydrate-based economy. Poly(3-hydroxybutyrate), PHB has attracted much commercial interest as a plastic and biodegradable material because some its physical properties are similar to those of polypropylene (PP), even though the two polymers have quite different chemical structures. PHB exhibits a high degree of crystallinity, has a high melting point of approximately 180°C, and most importantly, unlike PP, PHB is rapidly biodegradable. Two major factors which currently inhibit the widespread use of PHB are its high cost and poor mechanical properties. The production costs of PHB are significantly higher than for plastics produced from petrochemical resources (e.g. PP costs $US1 kg-1, whereas PHB costs $US8 kg-1), and its stiff and brittle nature makes processing difficult and impedes its ability to handle high impact. Lignin, together with cellulose and hemicellulose, are the three main components of every lignocellulosic biomass. It is a natural polymer occurring in the plant cell wall. Lignin, after cellulose, is the most abundant polymer in nature. It is extracted mainly as a by-product in the pulp and paper industry. Although, traditionally lignin is burnt in industry for energy, it has a lot of value-add properties. Lignin, which to date has not been exploited, is an amorphous polymer with hydrophobic behaviour. These make it a good candidate for blending with PHB and technically, blending can be a viable solution for price and reduction and enhance production properties. Theoretically, lignin and PHB affect the physiochemical properties of each other when they become miscible in a composite. A comprehensive study on structural, thermal, rheological and environmental properties of lignin/PHB blends together with neat lignin and PHB is the targeted scope of this thesis. An introduction to this research, including a description of the research problem, a literature review and an account of the research progress linking the research papers is presented in Chapter 1. In this research, lignin was obtained from bagasse through extraction with sodium hydroxide. A novel two-step pH precipitation procedure was used to recover soda lignin with the purity of 96.3 wt% from the black liquor (i.e. the spent sodium hydroxide solution). The precipitation process is presented in Chapter 2. A sequential solvent extraction process was used to fractionate the soda lignin into three fractions. These fractions, together with the soda lignin, were characterised to determine elemental composition, purity, carbohydrate content, molecular weight, and functional group content. The thermal properties of the lignins were also determined. The results are presented and discussed in Chapter 2. On the basis of the type and quantity of functional groups, attempts were made to identify potential applications for each of the individual lignins. As an addendum to the general section on the development of composite materials of lignin, which includes Chapters 1 and 2, studies on the kinetics of bagasse thermal degradation are presented in Appendix 1. The work showed that distinct stages of mass losses depend on residual sucrose. As the development of value-added products from lignin will improve the economics of cellulosic ethanol, a review on lignin applications, which included lignin/PHB composites, is presented in Appendix 2. Chapters 3, 4 and 5 are dedicated to investigations of the properties of soda lignin/PHB composites. Chapter 3 reports on the thermal stability and miscibility of the blends. Although the addition of soda lignin shifts the onset of PHB decomposition to lower temperatures, the lignin/PHB blends are thermally more stable over a wider temperature range. The results from the thermal study also indicated that blends containing up to 40 wt% soda lignin were miscible. The Tg data for these blends fitted nicely to the Gordon-Taylor and Kwei models. Fourier transform infrared spectroscopy (FT-IR) evaluation showed that the miscibility of the blends was because of specific hydrogen bonding (and similar interactions) between reactive phenolic hydroxyl groups of lignin and the carbonyl group of PHB. The thermophysical and rheological properties of soda lignin/PHB blends are presented in Chapter 4. In this chapter, the kinetics of thermal degradation of the blends is studied using thermogravimetric analysis (TGA). This preliminary investigation is limited to the processing temperature of blend manufacturing. Of significance in the study, is the drop in the apparent energy of activation, Ea from 112 kJmol-1 for pure PHB to half that value for blends. This means that the addition of lignin to PHB reduces the thermal stability of PHB, and that the comparative reduced weight loss observed in the TGA data is associated with the slower rate of lignin degradation in the composite. The Tg of PHB, as well as its melting temperature, melting enthalpy, crystallinity and melting point decrease with increase in lignin content. Results from the rheological investigation showed that at low lignin content (.30 wt%), lignin acts as a plasticiser for PHB, while at high lignin content it acts as a filler. Chapter 5 is dedicated to the environmental study of soda lignin/PHB blends. The biodegradability of lignin/PHB blends is compared to that of PHB using the standard soil burial test. To obtain acceptable biodegradation data, samples were buried for 12 months under controlled conditions. Gravimetric analysis, TGA, optical microscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), FT-IR, and X-ray photoelectron spectroscopy (XPS) were used in the study. The results clearly demonstrated that lignin retards the biodegradation of PHB, and that the miscible blends were more resistant to degradation compared to the immiscible blends. To obtain an understanding between the structure of lignin and the properties of the blends, a methanol-soluble lignin, which contains 3× less phenolic hydroxyl group that its parent soda lignin used in preparing blends for the work reported in Chapters 3 and 4, was blended with PHB and the properties of the blends investigated. The results are reported in Chapter 6. At up to 40 wt% methanolsoluble lignin, the experimental data fitted the Gordon-Taylor and Kwei models, similar to the results obtained soda lignin-based blends. However, the values obtained for the interactive parameters for the methanol-soluble lignin blends were slightly lower than the blends obtained with soda lignin indicating weaker association between methanol-soluble lignin and PHB. FT-IR data confirmed that hydrogen bonding is the main interactive force between the reactive functional groups of lignin and the carbonyl group of PHB. In summary, the structural differences existing between the two lignins did not manifest itself in the properties of their blends.

Influence of physical and chemical properties of solids on heavy metal adsorption

Partition of heavy metals between particulate and dissolve fraction of stormwater primarily depends on the adsorption characteristics of solids particles. Moreover, the bioavailability of heavy metals is also influenced by the adsorption behaviour of solids. However, due to the lack of fundamental knowledge in relation to the heavy metals adsorption processes of road deposited solids, the effectiveness of stormwater management strategies can be limited. The research study focused on the investigation of the physical and chemical parameters of solids on urban road surfaces and, more specifically, on heavy metal adsorption to solids. Due to the complex nature of heavy metal interaction with solids, a substantial database was generated through a series of field investigations and laboratory experiments. The study sites for the build-up pollutant sample collection were selected from four urbanised suburbs located in a major river catchment. Sixteen road sites were selected from these suburbs and represented typical industrial, commercial and residential land uses. Build-up pollutants were collected using a wet and dry vacuum collection technique which was specially designed to improve fine particle collection. Roadside soil samples were also collected from each suburb for comparison with the road surface solids. The collected build-up solids samples were separated into four particle size ranges and tested for a range of physical and chemical parameters. The solids build-up on road surfaces contained a high fraction (70%) of particles smaller than 150ìm, which are favourable for heavy metal adsorption. These solids particles predominantly consist of soil derived minerals which included quartz, albite, microcline, muscovite and chlorite. Additionally, a high percentage of amorphous content was also identified in road deposited solids. In comparing the mineralogical data of surrounding soil and road deposited solids, it was found that about 30% of the solids consisted of particles generated from traffic related activities on road surfaces. Significant difference in mineralogical composition was noted in different particle sizes of build-up solids. Fine solids particles (<150ìm) consisted of a clayey matrix and high amorphous content (in the region of 40%) while coarse particles (>150ìm) consisted of a sandy matrix at all study sites, with about 60% quartz content. Due to these differences in mineralogical components, particles larger than and smaller than 150ìm had significant differences in their specific surface area (SSA) and effective cation exchange capacity (ECEC). These parameters, in turn, exert a significant influence on heavy metal adsorption. Consequently, heavy metal content in >150ìm particles was lower than in the case of fine particles. The particle size range <75ìm had the highest heavy metal content, corresponding with its high clay forming minerals, high organic matter and low quartz content which increased the SSA, ECEC and the presence of Fe, Al and Mn oxides. The clay forming minerals, high organic matter and Fe, Al and Mn oxides create distinct groups of charge sites on solids surfaces and exhibit different adsorption mechanisms and bond strength, between heavy metal elements and charge sites. Therefore, the predominance of these factors in different particle sizes leads to different heavy metal adsorption characteristics. Heavy metals show preference for association with clay forming minerals in fine solids particles, whilst in coarse particles heavy metals preferentially associate with organic matter. Although heavy metal adsorption to amorphous material is very low, the heavy metals embedded in traffic related materials have a potential impact on stormwater quality.Adsorption of heavy metals is not confined to an individual type of charge site in solids, whereas specific heavy metal elements show preference for adsorption to several different types of charge sites in solids. This is attributed to the dearth of preferred binding sites and the inability to reach the preferred binding sites due to competition between different heavy metal species. This confirms that heavy metal adsorption is significantly influenced by the physical and chemical parameters of solids that lead to a heterogeneity of surface charge sites. The research study highlighted the importance of removal of solids particles from stormwater runoff before they enter into receiving waters to reduce the potential risk posed by the bioavailability of heavy metals. The bioavailability of heavy metals not only results from the easily mobile fraction bound to the solids particles, but can also occur as a result of the dissolution of other forms of bonds by chemical changes in stormwater or microbial activity. Due to the diversity in the composition of the different particle sizes of solids and the characteristics and amount of charge sites on the particle surfaces, investigations using bulk solids are not adequate to gain an understanding of the heavy metal adsorption processes of solids particles. Therefore, the investigation of different particle size ranges is recommended for enhancing stormwater quality management practices.

Volatile properties of particles emitted by compressed natural gas and diesel buses during steady state and transient driving modes

Volatile properties of particle emissions from four compressed natural gas (CNG) and four diesel buses were investigated under steady state and transient driving modes on a chassis dynamometer. The exhaust was diluted utilising a full-flow continuous volume sampling system and passed through a thermodenuder at controlled temperature. Particle number concentration and size distribution were measured with a condensation particle counter and a scanning mobility particle sizer, respectively. We show that, while almost all the particles emitted by the CNG buses were in the nanoparticle size range, at least 85% and 98% were removed at 100ºC and 250ºC, respectively. Closer analysis of the volatility of particles emitted during transient cycles showed that volatilisation began at around 40°C with the majority occurring by 80°C. Particles produced during hard acceleration from rest exhibited lower volatility than that produced during other times of the cycle. Based on our results and the observation of ash deposits on the walls of the tailpipes, we suggest that these non-volatile particles were composed mostly of ash from lubricating oil. Heating the diesel bus emissions to 100ºC removed ultrafine particle numbers by 69% to 82% when a nucleation mode was present and just 18% when it was not.

An investigation of building physical properties selection to combat global warming

Global warming can have a significant impact on building energy performance and indoor thermal environment, as well as the health and productivity of people living and working inside them. Through the building simulation technique, this paper investigates the adaptation potential of different selections of building physical properties to increased outdoor temperature in Australia. It is found that overall, an office building with lower insulation level, smaller window to wall ratio and/or a glass type with lower shading coefficient, and lower internal load density will have the effect of lowering building cooling load and total energy use, and therefore have a better potential to adapt to the warming external climate. Compared with clear glass, it is shown that the use of reflective glass for the sample building with WWR being 0.5 reduces the building cooling load by more than 12%. A lower internal load can also have a significant impact on the reduction of building cooling load, as well as the building energy use. Through the comparison of results between current and future weather scenarios, it is found that the patterns found in the current weather scenario also exist in the future weather scenarios, but to a smaller extent.

Studies on the surface properties of biodegradable polymer carriers in respiratory delivery of drug from Dry Powder Inhaler formulations

Dry Powder Inhaler (DPI) technology has a significant impact in the treatment of various respiratory disorders. DPI formulations consist of a micronized drug (<5ìm) blended with an inert coarse carrier, for which lactose is widely used to date. DPIs are one of the inhalation devices which are used to target the delivery of drugs to the lungs. Drug delivery via DPI formulations is influenced by the physico-chemical characteristics of lactose particles such as size, shape, surface roughness and adhesional forces. Commercially available DPI formulations, which utilise lactose as the carrier, are not efficient in delivering drug to the lungs. The reasons for this are the surface morphology, adhesional properties and surface roughness of lactose. Despite several attempts to modify lactose, the maximum efficient drug delivery to the lungs remains limited; hence, exploring suitable alternative carriers for DPIs is of paramount importance. Therefore, the objective of the project was to study the performance of spherical polymer microparticles as drug carriers and the factors controlling their performance. This study aimed to use biodegradable polymer microspheres as alternative carriers to lactose in DPIs for achieving efficient drug delivery into the lungs. This project focused on fabricating biodegradable polymer microparticles with reproducible surface morphology and particle shape. The surface characteristics of polymeric carriers and the adhesional forces between the drug and carrier particles were investigated in order to gain a better understanding of their influence on drug dispersion. For this purpose, two biodegradable polymers- polycaprolactone (PCL) and poly (DL-lactide-co-glycolide) (PLGA) were used as the carriers to deliver the anti-asthmatic drug - Salbutamol Sulphate (SS). The first study conducted for this dissertation was the aerosolization of SS from mixtures of SS and PCL or PLGA microparticles. The microparticles were fabricated using an emulsion technique and were characterized by laser diffraction for particle size analysis, Scanning Electron Microscopy (SEM) for surface morphology and X-ray Photoelectron Spectroscopy (XPS) to obtain surface elemental composition. The dispersion of the drug from the DPI formulations was determined by using a Twin Stage Impinger (TSI). The Fine particle Fraction (FPF) of SS from powder mixtures was analyzed by High Performance Liquid Chromatography (HPLC). It was found that the drug did not detach from the surface of PCL microspheres. To overcome this, the microspheres were coated with anti-adherent agents such as magnesium stearate and leucine to improve the dispersion of the drug from the carrier surfaces. It was found that coating the PCL microspheres helped in significantly improving the FPF of SS from the PCL surface. These results were in contrast to the PLGA microspheres which readily allowed detachment of the SS from their surface. However, coating PLGA microspheres with antiadherent agents did not further improve the detachment of the drug from the surface. Thus, the first part of the study demonstrated that the surface-coated PCL microspheres and PLGA microspheres can be potential alternatives to lactose as carriers in DPI formulations; however, there was no significant improvement in the FPF of the drug. The second part of the research studied the influence of the size of the microspheres on the FPF of the drug. For this purpose, four different sizes (25 ìm, 48 ìm, 100 ìm and 150 ìm) of the PCL and PLGA microspheres were fabricated and characterized. The dispersion of the drug from microspheres of different sizes was determined. It was found that as the size of the carrier increased there was a significant increase in the FPF of SS. This study suggested that the size of the carrier plays an important role in the dispersion of the drug from the carrier surface. Subsequent experiments in the third part of the dissertation studied the surface properties of the polymeric carrier. The adhesion forces existing between the drug particle and the polymer surfaces, and the surface roughness of the carriers were quantified using Atomic Force Microscopy (AFM). A direct correlation between adhesion forces and dispersion of the drug from the carrier surface was observed suggesting that adhesion forces play an important role in determining the detachment potential of the drug from the carrier surface. However, no direct relationship between the surface roughness of the PCL or PLGA carrier and the FPF of the drug was observed. In conclusion, the body of work presented in this dissertation demonstrated the potential of coated PCL microspheres and PLGA microspheres to be used in DPI formulations as an alternative carrier to sugar based carriers. The study also emphasized the role of the size of the carrier particles and the forces of interaction prevailing between the drug and the carrier particle surface on the aerosolization performances of the drug.

Are insect frugivores always plant pests? The impact of fruit fly (Diptera: Tephritidae) larvae on host plant fitness

Herbivory is generally regarded as negatively impacting on host plant fitness. Frugivorous insects, which feed directly on plant reproductive tissues, are predicted to be particularly damaging to hosts. We tested this prediction with the fruit fly, Bactrocera tryoni, by recording the impact of larval feeding on two direct (seed number and germination) and two indirect (fruit decay rate and attraction/deterrence of vertebrate frugivores) measures of host plant fitness. Experiments were done in the laboratory, glasshouse and tropical rainforest. We found no negative impact of larval feeding on seed number or germination for three test plants: tomato, capsicum and eggplant. Further, larval feeding accelerated the initiation of decay and increased the final level of fruit decay in tomatoes, apples, pawpaw and pear, a result considered to be beneficial to the fruit. In rainforest studies, native rodents preferred infested apple and pears compared to uninfested control fruit; however, there were no differences observed between treatments for tomato and pawpaw. For our study fruits, these results demonstrate that fruit fly larval infestation has neutral or beneficial impacts on the host plant, an outcome which may be largely influenced by the physical properties of the host. These results may contribute to explaining why fruit flies have not evolved the same level of host specialization generally observed for other herbivore groups.