Wood is a highly versatile renewable material (with carbon sequestering properties), that is light in weight, has good strength properties in both tension and compression while providing good rigidity and toughness, and good insulating properties (relative to typical structural materials). Engineered wood products combine the benefits of wood with engineering knowledge to create optimized structural elements. Cross-laminated timber (CLT), as one such engineered wood product, is an emerging engineering material which provides great opportunities for the building industry. While building with wood has many benefits, there are also some concerns, particularly decay. Should wood be exposed to elevated amounts of moisture, rots and moulds may damage the product or even risk the health of the occupants. As CLT panels are a relatively new engineered wood product, the moisture characteristics have yet to be properly assessed. Consequently, the amount of decay risk for CLT in building applications is unknown, and recommended protective actions during design construction and operation have yet to be determined. The goal of this research was to determine the moisture durability of CLT panels in wall assemblies and address concerns related to built-in construction moisture. The approach used to address the problem was to first determine select moisture properties of CLT panels through experimental approaches, and then use the results to calibrate a hygrothermal model to quantify the risks of wall assemblies. The wall assemblies were simulated in six different cities across Canada, representing a range of climates: Vancouver, B.C., Edmonton, A.B., Winnipeg, M.B., Ottawa, O.N., Québec City, Q.C., and St. John, New-Brunswick. The risks associated with moisture exposure during construction are also considered in the simulations. The experimental phase of the research was limited to moisture uptake tests. These tests were utilized to determine the liquid water absorption coefficient for four different types of full scale panels (2’x2’) and 12 clear wood samples. The panels were either made of 5-ply of Western-SPF, Eastern-SPF, Hemlock-Fir, or 3-ply of a generic softwood provided by a European CLT manufacturer; the clear samples were all cut from the same nominal 2x6 SPF-grade lumber. The panels were installed in a drying rack and gravimetrically tracked to assess the drying rates of the panels. Finite resources precluded more thorough material testing, but a parametric study was conducted to determine the relative impact of the missing material data on the final simulation results. In the hygrothermal simulations, four main wall assembly types were considered- those with either exterior or interior insulation, and those using either vapour permeable or impermeable air-water barriers. Various types of insulation and vapour control were also modelled. The simulations were run for a variety of interior relative humidities. The metric for comparison between the simulations was the water content of a 4mm thin layer on the extreme lamina of a CLT panel system. The results of the simulation suggest that vapour impermeable membranes, when install on dry CLT panels (less than 14% M.C.) do not pose moisture risks in any of the climates considered. However, when high levels of construction moisture is considered, only vapour permeable membranes controlled moisture risks by allowing the CLT panel to dry both to the interior and to the exterior.

This study covers grafting of Acrylic Acid (AA) and Methacrylic Acid (MAA) on Ultrahigh Molecular Weight Polyethylene (UHMWPE) thin films by surface grafting and xylene-swollen grafting methods with Co-60 &amp / #947 / -ray in air. Also characterizations of pure, irradiated and grafted films were made by applying gravimetric, spectroscopic, thermal and mechanic tests. The thin films of UHMWPE were prepared by using compression molding. AA and MAA grafting on thin UHMWPE films were carried out by surface grafting and xylene-swollen grafting methods. During grafting processes, homopolymerization of monomers was avoided by using Fe2+ and Cu2+ ions. Grafting degree of AA and MAA were calculated for the samples irradiated at different doses. To verify grafting of AA and MAA on UHMWPE films, FTIR spectra of grafted films were used. Metal-uptake capacity is important property of grafted polyethylene for environmental applications. Thus, we examined metal-uptake capacities of AA and MAA grafted films for Fe(III) and Ni (II) and it was found that AA and MAA grafted UHMWPE films showed good affinity towards Fe(III) and Ni(II) metals. Thermal behavior of films were examined by DSC analysis. First run and second run DSC thermograms showed the thermal stability of films under heat. Mechanical properties of UHMWPE decrease with irradiation and grafting. However stress at break values of xylene-swollen grafted samples tend to increase with irradiation dose. In conclusion, water soluble monomers were successfully grafted on UHMWPE and these AA and MAA grafted UHMWPE films can be used in biomedical, environmental applications and other related areas.

TRANSCRIPTIONAL ANALYSIS OF HYDROGENASE GENES IN RHODOBACTER SPHAEROIDES O.U.001 In photosynthetic non-sulphur bacteria, hydrogen production is catalyzed by nitrogenases and hydrogenases. Hydrogenases are metalloenzymes that are basically classified into: the Fe hydrogenases, the Ni-Fe hydrogenases and metal-free hydrogenases. Two distinct Ni-Fe hydrogenases are described as uptake hydrogenases and bidirectional hydrogenases. The uptake hydrogenases are membrane bound dimeric enzymes consisting of small (hupS) and large (hupL) subunits, and are involved in uptake and the recycling of hydrogen, providing energy for nitrogen fixation and other metabolic processes. In this study the presence of the uptake hydrogenase genes was shown in Rhodobacter sphaeroides O.U.001 strain for the first time and hupS gene sequence was determined. The sequence shows 93% of homology with the uptake hydrogenase hupS of R.sphaeroides R.V. There was no significant change in growth of the bacteria at different concentrations of metal ions (nickel, molybdenum and iron in growth media). The effect of metal ions on hydrogen production of the organism was also studied. The maximum hydrogen gas production was achieved in 8.4&micro / M of nickel and 0.1 mM of iron containing media. The expression of uptake hydrogenase genes were examined by RT-PCR. Increasing the concentration of Ni++ up to 8.4&micro / M increased the expression of uptake hydrogenase genes (hupS). At varied concentrations of Fe-citrate (0.01 mM-0.1 mM) expression of hupS was not detected until hydrogen production stopped. These results will be significant for the improvement strategies of Rhodobacter sphaeroides O.U.001 to increase hydrogen production efficiency. In order to examine the presence of hupL genes, different primers were designed. However, the products could not be observed by PCR.

Assaying internal contamination due to inhalation is a primary concern in developing emergency procedures related to Radioactive Dispersal Devices (RDD). One method of determining internal contamination makes use of a common medical instrument, a Thyroid Uptake System (TUS). The TUS used in this research has two collimators a thyroid uptake collimator and a bioassay collimator. Both collimators were considered and modeled in MCNP to be used in conjunction with six MIRD-type (Medical Internal Radiation Dose) phantoms. The collimators were placed in four positions on the phantoms the front right lung, the back right lung, the neck, and the thigh. Unit sources of Cs-137, Co-60, I-131, Ir-192, Am-241, and Sr/Y-90 were placed in the organs of the phantoms. MCNP particle tallies were performed over the detector crystal volume to determine the count-rate contributions from the unit source in each organ. Biokinetic modeling was performed using DCAL (Dose and Risk Calculation System) to generate coefficients to describe activity as a function of time in various organs. By folding the count-rate results with the organ concentrations, the detector response as a function of time after intake has been determined. This work was performed under funding provided by the Radiation Studies Branch of the Centers for Disease Control and Prevention.

The blood-brain barrier (BBB) controls the movement of substances into and out of the brain. The tight junctions between endothelial cells and energy dependent transporters in the BBB influence rate and extent of drug distribution to the brain. The aim of this thesis was to study different methodological and pharmacokinetic aspects of drug transport at the BBB by characterizing possible active uptake and drug-drug interactions. Therefore, advanced tools for data acquisition and analysis were applied. The role of BBB transport in early drug development, with particular emphasis on in vitro-in vivo comparisons and species differences, was also investigated. Microdialysis in rats was used to study the BBB pharmacokinetics of oxymorphone, diphenhydramine (DPHM), oxycodone and morphine. Oxymorphone, DPHM and verapamil were all found to be actively taken up at the BBB, with brain to blood unbound drug ratios of 2, 5 and 2, respectively. The effect profile for oxycodone was successfully described using the modified M3 method for censored observations. In vitro experiments indicated a competitive interaction between DPHM and oxycodone on active uptake transport to the brain. No such interaction was observed in vivo due to much lower unbound concentrations achieved, compared with the in vitro Ki values. Active uptake of morphine at the BBB was not demonstrated even at very low concentrations as it was not possible to separate the active uptake transport process from active efflux by decreasing the morphine concentration. Mice carrying the human P-gp gene (hMDR1) were used to evaluate possible species differences in P-gp function. Differences were evident between the hMDR1 and normal mice in BBB penetration of various P-gp substrates and in the effect of blockers on P-gp function. Quantitative measurements of P-gp expression levels at the BBB and a comparison with human data are crucial for the future use of the hMDR1 model. In conclusion, this thesis reports active uptake of oxymorphone, DPHM and verapamil at the BBB. In vivo interaction of DPHM and oxycodone at the BBB was found not to be significant at therapeutic drug concentrations. Furthermore species differences were found between human and mouse P-gp function at the BBB.

Phytoplankton dynamics and chemical characteristics of the euphotic zone were measured from 1998-2000 (an El Niño/La Niña cycle) at the 5 major stations along Line P. Near-shelf and offshore stations exhibited low seasonality in chlorophyll and moderate seasonality in particulate organic carbon (POC) production. During the 1998 El Niño, June was characterized by low chlorophyll and POC productivity due to nitrate depletion. In contrast, during the 1999 La Niña, and in 2000, higher POC productivity and nitrate occurred in June. During 1999, chlorophyll and POC productivity were similar to 1998 in late summer. Near-shelf biomass was highest in June and lowest in Feb. for the near-shelf stations. High nitrate, low chlorophyll (HNLC) stations had the highest chlorophyll in Feb. followed by June. The coccolithophore assemblage was usually numerically dominated by Emiliania huxleyi, particularly in June. Along the transect, coccolithophore abundance was much higher in June during the 1998 El Niño than in the 1999 La Niña, with Aug./Sept. abundance of both years being very low. Higher abundances were measured along the transect in June and the late summer of 2000 with sporadic ‘blooms’ of >1000 cells ml⁻¹ at some stations. Particulate inorganic carbon (PIC) production was high along the transect during June 1998, and low during both winters, June 1999 and during late summers of 1998 and 1999. There was an increase in diatom biomass and >20 µm POC production during the 1998 El Niño, specifically in the farthest offshore HNLC stations, yet diatoms were rarely found to dominate total phytoplankton biomass or production. However, there were some sporadic examples of anomalously high diatom biomass (carbon and abundance) as well as >20 µm POC production, specifically at P12 in Aug./Sept 2000. The same major diatom species were found throughout Line P (near-shelf, P16, and HNLC). Integrated silica production measured by ³²Si ranged from 0.2 to 4.7 mmol Si m⁻² d⁻¹ between 1999-2000. Silicic acid and nitrate were never limiting at all stations in Feb. and generally increased in concentration along Line P during all seasons.

BspA was first identified on the basis of being the major constituent of 5 M LiCl washes of whole Lactobacillus fermentum BR11 cells. The bspA gene is encoded within a putative ATP-binding cassette (ABC) transport operon, and sequence analysis revealed that it is a member of the family III solute binding proteins. Unlike the majority of solute binding proteins from Gram-positive bacteria, BspA is not tethered to a lipid anchor in the cell membrane, and hence is not a lipoprotein. Extraction of BspA with concentrated salt solutions such as 5 M LiCl is consistent with the notion that electrostatic interactions are responsible for securing it to the L. fermentum BR11 cell. L. fermentum PNG201 is a BspA negative mutant strain created by disrupting bspA. This strain was shown to be incapable of cystine uptake. Thus, the genetic and biochemical evidence strongly suggests BspA is a cystine binding protein of an ABC transporter. Measurement of the binding affinity between BspA and L-cystine has confirmed high affinity binding (dissociation constant is 0.2 µM), and high specificity (over 100-fold excess of non-target amino acids did not disrupt BspA / L-cystine binding). In addition, collagen did not appear to affect BspA/cystine binding, indicating extracellular matrix (ECM) binding capacity noted by other researchers may be unrelated to amino acid binding. An interesting phenotypic characteristic of L. fermentum PNG201 is its apparent increased sensitivity to oxygen and the superoxide-generating chemical - paraquat compared to the parent L. fermentum BR11 strain. Catalase supplemented aerobic cultures of L. fermentum BR11, and L. fermentum PNG201 were protected from oxidative stress, suggesting hydrogen peroxide is responsible for the observed oxidative stress. It was found that addition of cystine to aerobic cultures of L. fermentum BR11 or L. fermentum PNG201 protected both strains from oxidative stress, with L. fermentum BR11 able to utilize smaller concentrations of cystine compared to L. fermentum PNG201. Detection of hydrogen peroxide in aerobic cultures of L. fermentum BR11 and L. fermentum PNG201 confirmed the production of hydrogen peroxide is responsible for causing oxidative stress. The BspA mutant strain L. fermentum PNG201 consistently produced more hydrogen peroxide per optical density compared with the wild type, indicating it overproduced hydrogen peroxide. When 0.4 mM hydrogen peroxide has been accumulated by growing cell cultures, both L. fermentum BR11 and L. fermentum PNG201 enters stationary phase, suggesting both strains have a similar sensitivity to hydrogen peroxide. Small epitopes from the HIV gp41 protein and the Chlamydia psittaci major outer membrane protein have been successfully displayed on the cell surface of L. fermentum BR11 as fusion proteins to the BspA molecule. However, the capability of BspA in exporting larger polypeptides has not been tested. In this study, the large extracellular enzyme - glucosyltransferase (GtfJ) from Streptococcus salivarius ATCC 25975 was fused to BspA to demonstrate that this expression system is capable of exporting large functional enzymes to the cell surface of L. fermentum BR11. The native GtfJ is 160kDa in size and also contained an export signal, which was deleted in the cloning process and replaced with BspA, resulting in a fusion protein of 175kDa. Export of the BspA/GtfJ fusion protein is dependant entirely on BspA's export signal. Recombinant enzyme expression and glucosyltransferase activity were detected by measuring the glucan formed by sonicated cell extracts in acrylamide gels. Enzyme activity measurements on whole cells has revealed the recombinant Lactobacillus was incorporating 20-40 nmol of sucrose-derived-glucose into glucan per ml of cell culture per OD unit, which is comparable to activity levels exhibited by the native bacteria that expressed this enzyme. Comparison of GtfJ enzyme activity between whole cells and sonicated cell extracts of recombinant L. fermentum confirmed the extracellular location of BspA/GtfJ as enzyme activity was essentially identical.

The South Burnett region of Queensland is Australia's most important rainfed peanut (Arachis hypogea L.) production area. It also produces a considerable amount of cereal and grain legume crops. The cropping soils of the region are red, acid to neutral, clay loams that are classified as Ferrosols (Australian Soil Classification). Over 50 years of cropping on these soils has resulted in severe depletion of nutrient reserves, particularly potassium (K). In addition, the remaining K is predominantly confined to the surface 10 or 15cm of the soil profile, a feature commonly refered to as nutrient stratification. Dry periods during the summer cropping season are common due to the highly variable, summer-dominant rainfall pattern of the South Burnett. As topsoil dries out, crops forage for moisture and nutrients from lower in the soil profile where K reserves are smaller. It is therefore suspected that the combination of dry periods and stratified K reserves have resulted in an increasing incidence of K deficiency symptoms in summer crops. To investigate these issues, K relations of Ferrosols of the South Burnett were studied using soils from two representative sites. The pools of soil K that are important to crop growth in Ferrosols, and their interaction was examined through fractionation of soil K pools, and determination of quantity/intensity relationships, charge characteristics and clay mineralogy, and a leaching column study. A rapid K uptake period was identified for peanut and the effect of profile distribution and soil moisture during this period on K accessibility was studied in a divided column experiment. Finally, on-farm trials were used to evaluate commercial-scale options for improving K distribution in field profiles. It was found that the immediately available exchangeable K pool in these soils was the most important source of soil K, and was poorly buffered by slowly available non-exchangeable K. However the leaching column study revealed that K was preferentially adsorbed onto soil cation exchange sites, displacing calcium (Ca) and magnesium (Mg) ions, and therefore was not susceptible to vertical movement within the soil profile. These observations helped to explain the development of stratified K profiles in these soil types. Peanut (cv. Streeton) was found to take up most of its K requirement between 25-70 days after planting. The divided column study showed that profile distribution, and topsoil iv moisture content during this rapid K uptake period, were able to affect the ability of peanut plants to access K. Plants that grew in low K soil, or where soil was dry at the site of K supply, had reduced access to K. However, improving access to K did not result in improved growth, but rather in a significant reduction in dry matter (DM) production, apparently due to interference in the availability of other nutrients, possibly phosphorus (P), magnesium (Mg) or boron (B). Field studies showed that application of K and profile inversion improved K uptake and DM production of various crop species. However, in most instances improved K uptake and DM production was not reflected in increased yield. It was suggested that a combination of agronomic factors, seasonal conditions and crop type prevented the expression of yield responses to improved K nutrition and these influences need to be understood. The findings of this project have important consequences for nutrition of crops grown on Ferrosols in the South Burnett region. Surface applied K cannot be expected to increase exchangeable K in the subsoil unless it is incorporated to depth. Similarly, band applied K will remain close to the site of application as a result of only limited vertical or lateral movement. This may affect the ability of roots to access band applied K. The ability of surface applied K to displace Ca and Mg from soil exchange sites may have negative implications for the Ca nutrition of developing peanut pods. On the other hand, it could present an opportunity for the movement of Ca into deeper soil layers to address the amelioration of acid subsoils. The unexplained negative responses to potassium chloride application and apparent effect on P, Mg or B nutrition need to be investigated.

This thesis considers the implications of changes in the supply of resources for photosynthesis, with regard for modes of carbon acquisition employed by aquatic plants of the River Murray. Carbon supplies are inherently more variable for aquatic plants than for those in terrestrial environments, and variations are intensified for plants in semi-arid regions, where water may be limiting. In changeable environments the most successful species are likely to be those with flexible carbon-uptake mechanisms, able to accommodate variations in the supply of resources. Studies were made of plants associated with wetland habitats of the Murray, including Crassula helmsii, Potamogeton tricarinatus, P. crispus and Vallisneria americana. The aim was to elucidate the mechanisms of carbon uptake and assimilation employed, and to determine how flexibility in carbon uptake and/or assimilation physiology affect survival and distribution. Stable carbon isotopes were used to explore the dynamics of carbon uptake and assimilation, and fluorescence was used to identify pathways and photosynthetic capacity. The studies suggest that physiological flexibility is adaptive survival in changeable environments, but probably does not enhance the spread or dominance of these species. V. americana is a known bicarbonate-user, and it is shown here that it uses the Crassulacean Acid Metabolism (CAM) photosynthetic pathway under specific conditions (high light intensity near the leaf tips) concurrently with HCO[subscript]3 - uptake, while leaves deeper in the water continue to use the C[subscript]3 pathway, with CO₂ as the main carbon source. However, V. americana does not use CAM when under stress, such as exposure to high light and temperature. The diversity of carbon uptake and assimilation mechanisms in this species may explain its competitive ability in habitats associated with the Murray. In this way it is able to maximise use of light throughout the water column. In shallow, warm water, where leaves are parallel to the surface, CAM ability is likely to be induced along the length of the leaf, allowing maximal use of carbon and light. The amphibious C. helmsii is shown to use CAM on submergence, even where water levels fluctuate within 24 hours. This allows continued photosynthesis in habitats where level fluctuations prevent access to atmospheric CO₂. It appears that stable conditions are most favourable for growth and dispersal, and that the spread of C. helmsii is mainly by the aerial form. Carbon uptake by P. tricarinatus under field conditions is compared with that of P. crispus to demonstrate differences in productivity associated with aqueous bicarbonate and atmospheric CO₂ use. P. tricarinatus uses HCO[subscript]3 - uptake to promote growth toward the surface, so that CO₂ can be accessed by floating leaves. Atmospheric contact provides access to light and removes the limitation of aqueous diffusive resistance to CO₂, thereby increasing photosynthetic capacity above that provided by submerged leaves. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1320380 / Thesis (Ph.D) -- University of Adelaide, School of Earth and Environmental Sciences, 2008

Lymphocytes from normal subjects and patients with B-chronic lymphocytic leukemia (B-CLL) show functional responses to extracellular ATP characteristic of the P2X7 receptor. These responses include opening of a cation selective channel/pore which allows entry of the fluorescent dye, ethidium+ and activation of a membrane metalloprotease which sheds the adhesion molecule L-selectin. In this thesis, the surface expression of P2X7 receptors was measured in normal leucocytes, platelets and B-CLL lymphocytes and compared with their functional responses. Monocytes showed 4-5 fold greater expression of P2X7 than B-, T- and NK- lymphocytes, while P2X7 expression on neutrophils and platelets was weak. All cell types demonstrated abundant intracellular expression of this receptor. All 12 subjects with B-CLL expressed surface P2X7 at about the same level as for B-lymphocytes from normal subjects. P2X7 function, measured by ATP-induced uptake of ethidium, correlated closely with surface expression of this receptor in normal and B-CLL lymphocytes and monocytes. However, the ATP-induced uptake of ethidium into the malignant B-lymphocytes in 3 patients was low or absent. The lack of P2X7 function in these B-lymphocytes was confirmed by the failure of ATP to induce Ba2+ uptake into their lymphocytes. This lack of function of the P2X7 receptor resulted in a failure of ATP-induced shedding of L-selectin, an adhesion molecule which directs the recirculation of lymphocytes from blood into the lymph node. To study a possible genetic basis of non-functional P2X7 receptor, we sequenced DNA coding for the carboxyl terminal tail of P2X7. In 33 of 130 normal subjects a heterozygous nucleotide substitution (1513A--C) was found while 3 subject carried the homozygous substitution which codes for glutamic acid to alanine at amino acid position 496. Surface expression of P2X7 on lymphocytes was not affected by this 496Glu--Ala polymorphism demonstrated both by confocal microscopy and immunofluorescent staining. Monocytes and lymphocytes from the 496Glu--Ala homozygote subject expressed non-functional receptor while heterozygotes showed P2X7 function which was half that of wild type P2X7. Results of transfection experiments showed the mutant P2X7 receptor was non-functional when expressed at low receptor density but regained function at a high receptor density. This density-dependence of mutant P2X7 function was also seen on differentiation of fresh monocytes to macrophages with interferon-gamma which upregulated mutant P2X7 and partially restored its function. P2X7-mediated apoptosis of lymphocytes was impaired in homozygous mutant P2X7 compared with wild type. The data suggest that the glutamic acid at position 496 is required for optimal assembly of the P2X7 receptor. Apart from the 496Glu--Ala polymorphism, three other single nucleotide polymorphisms, 155His--Tyr, 348Ala--Thr and 568Ile--Asn were also found in the P2X7 receptor. The site directed mutant cDNA were generated for all 3 polymorphisms and transfected into HEK293 cells to study the impact of these polymorphisms on P2X7 function. Results suggested that Ile568 is important for P2X7 protein trafficking to cell surface. Further study of these two loss-of-function polymorphisms (496Glu--Ala and 568Ile--Asn) may help better understanding of the functional domains in the P2X7 receptor and its role in CLL, lymphoma and infectious diseases. Conclusions: 1.P2X7 receptor is expressed in human leukocytes, including lymphocytes, natural killer cells as well as monocytes, on both surface and intracellular locations. 2.Both the expression and function of P2X7 are highly variable between in human individuals. Non-functional P2X7 receptors are found in some subjects, including both normal subjects and CLL patients, and are often associated with defects in ATP-induced cytotoxicity and L-selectin shedding. 3.Two single nucleotide polymorphisms (SNPs), 496Glu--Ala and 568Ile--Asn, are found at low frequency in the human population and lead to the loss-of-function of P2X7. Both permeabllity function and the downstream effects mediated by P2X7 are affected by these two SNPs. The mechanisms for the loss-of-function differs between the two polymorphisms.