Browsing by Author "Nguyen, TH"
Now showing 1 - 6 of 6
Results Per Page
Sort Options
- ItemANSTO Radiocarbon Laboratory: developments to meet the needs of our community(Australian Nuclear Science and Technology Organisation, 2021-11-17) Bertuch, F; Williams, AA; Yang, B; Nguyen, TH; Varley, S; Jacobsen, GE; Hua, QThe radiocarbon chemistry laboratories in the Centre for Accelerator Science at the Australian Nuclear Science and Technology Organisation (ANSTO) have a role providing support to AMS measurements for government organisations, industry, and academia in Australia and overseas. Over recent years the radiocarbon laboratories at ANSTO have expanded to support projects that address unique challenges which include environmental issues, the sustainable management of water resources, climate variability, ecological studies, and research into Indigenous heritage. The increase of work in these areas has seen a growing demand for processing samples of groundwater, rock art, ice cores, tree rings and Antarctic mosses. Here we will present an update of our procedures for processing a diverse range of sample types. We will also describe developments such as an automated dissolved organic carbon (DIC) extraction system for water samples, and our automated AAA pretreatment system. We will also outline our range of graphitisation systems which include a set of 24 Fe/H2 graphitisation units, 6 microconventional furnace (MCF) Fe/H2 graphitisation lines, a laser heated furnace (LHF) graphitisation system, and an Ionplus AGE-3 graphitisation system (owned by UNSW). Our MCF and conventional graphitisation lines have been designed to handle and reliably produce graphite targets containing as little as 5 μg and 10ugC of carbon respectively), making the graphitisation of minute carbon samples from rock art and ice cores possible.
- ItemCoordination polymers of perylenetetracarboxylate with Cs(I) ions: 3D structures with 2D inorganic layers or triple coordination nets(Elsevier B. V., 2023-02) Nguyen, TH; Karatchevtseva, I; Bhadbhade, MM; Zhang, YJThe self-assembly of perylenetetracarboxylate (ptc) with Cs(I) ions at ambient temperature has been investigated with two coordination polymers being synthesized and structurally characterized. The diffusion of ethanol into a Cs-ptc solution led to the formation of compound 1 [(Cs4(ptc)(H2O)5·nH2O] displaying a compact three-dimensional (3D) structure constructed with 2D undulating layers of Cs polyhedra linked by ptc ligands in two types coordination modes. Extensive π···π interactions among stacking ptc ligands formed large hydrophobic organic channels between the inorganic layers. The addition of ethylenediamine (ED) to the reaction system afforded the formation of compound 2 [(H2ED)5Cs2(ptc)3(H2O)10] showing triple 2D coordination nets with protonated ethylene diammonium cations hydrogen-bonded to both non-bonded carboxyl oxygen and coordinated water molecules. The triple 2D nets are further linked via hydrogen bonding to form a 3D structure. The optical absorption, band gap analysis, vibrational modes and thermal stability of compound 1 were also investigated. Overall, the structural diversity was achieved in the studied self-assembly system at ambient temperature through varying Cs to ptc ratios by introducing ethylene diammonium as a non-metal cation. © 2023 Elsevier B.V.
- ItemDevelopment and characterisation of a small mass H2/Fe graphitisation line(12th International Conference on Accelerator Mass Spectrometry, 2011-03-24) Varley, S; Williams, AA; Nguyen, THWe will present the commissioning data for our prototype, small volume, conventional graphitisation line and a comparison will made with our 2.5 mL general purpose graphitisation lines. This new graphitisation line has an internal volume of ~1.1 mL and uses the H2/Fe graphitisation method. An Impress ME506 ceramic diaphragm pressure sensor is used in a custom stainless steel housing, which also incorporates the gas inlet valve and Ultratorr® style ports for connection of a replaceable graphitisation tube and cold finger. A custom designed, water cooled,resistance heated tube furnace is used to heat the Fe catalyst / reaction volume. To use with the new graphitisation line we have developed a small volume CO2 transfer line, which allows transfers from the sample combustion tube directly into the graphitisation line unit. This new transfer line has been developed using CF UHV fittings to minimise the possibility of sample contamination and leaks. Information will also be presented on a water-cooled, Peltier based chiller unit which is used to freeze out, at -52ºC, the water produced in the H2/Fe reaction. Protocols have been developed to minimise (and standardise) the quantity of the background carbon incorporated in the overall processing of the sample into graphite. Copyright (c) 2011 AMS12
- ItemNanostructure of liquid crystalline matrix determines in vitro sustained release and in vivo oral absorption kinetics for hydrophilic model drugs(Elsevier, 2009-01-05) Lee, KWY; Nguyen, TH; Hanley, TL; Boyd, BJNanostructured lipid-based liquid crystalline systems have been proposed as sustained oral drug delivery systems, but the interplay between their intrinsic release rates, susceptibility to digestive processes, and the manner in which these effects impact on their application in vivo, are not well understood. In this study, two different bicontinuous cubic phases, prepared from glyceryl monooleate and phytantriol, and a reversed hexagonal phase formed by addition of a small amount of vitamin E to phytantriol (Q(11 GMO). Q(11 PHYT) and H11 PHYT+VitEA, respectively) were prepared. The release kinetics for a number of model hydrophilic drugs with increasing molecular weights (glucose, Allura Red and FITC-clextrans) was determined in in vitro release experiments. Diffusion-controlled release was observed in all cases as anticipated from previous studies with liquid crystalline systems, and it was discovered that the release rates of each drug decreased as the matrix was changed from Q(11 GMO) to Q(11 PHYT) to H-11 PHYT VitEA. Formulations containing C-14-glucose, utilized as a rapidly absorbed marker of drug release, were then orally administered to rats to determine the relative in vivo absorption rates from the different formulations. The results showed a trend by which the rate of absorption of C-14-glucose followed that observed in the corresponding in vitro release studies, providing the first indication that the nanostructure of these materials may provide the ability to tailor the absorption kinetics of hydrophilic drugs in vivo, and hence form the basis of a new drug delivery system. © 2008, Elsevier Ltd.
- ItemPhytantriol and glyceryl monooleate cubic liquid crystalline phases as sustained-release oral drug delivery systems for poorly water soluble drugs I. Phase behaviour in physiologically-relevant media(Wiley-Blackwell, 2010-07) Nguyen, TH; Hanley, TL; Porter, CJH; Larson, I; Boyd, BJObjectives: the potential utility of liquid crystalline lipid-based formulations in oral drug delivery is expected to depend critically on their structure formation and stability in gastrointestinal fluids. The phase behaviour of lipid-based liquid crystals formed by phytantriol and glyceryl monooleate, known to form a bicontinuous cubic phase in excess water, was therefore assessed in physiologically-relevant simulated gastrointestinal media. Methods: fixed composition phase studies, crossed polarised light microscopy (CPLM) and small angle X-ray scattering (SAXS) were used to determine the phase structures formed in phosphate-buffered saline, simulated gastric and intestinal fluids in the presence of model poorly water soluble drugs cinnarizine, diazepam and vitamin E acetate. Key findings: the phase behaviour of phytantriol in phosphate-buffered saline was very similar to that in water. Increasing concentrations of bile components (bile salts and phospholipids) caused an increase in the lattice parameter of the cubic phase structure for both lipids. Incorporation of cinnarizine and diazepam did not influence the phase behaviour of the phytantriol- or glyceryl monooleate-based systems at physiological temperatures; however, an inverse hexagonal phase formed on incorporation of vitamin E acetate. Conclusions: Phytantriol and glyceryl monooleate have the potential to form stable cubic phase liquid crystalline delivery systems in the gastrointestinal tract. In-vivo studies to assess their sustained-release behaviour are warranted. © 2010, Wiley-Blackwell.
- ItemTesting line for processing of dissolved inorganic carbon from water for radiocarbon dating determining the efficacy of trapping carbon dioxide for an automated system(Australian Nuclear Science and Technology Organisation, 2021-11-17) Yang, B; Williams, AA; Nguyen, TH; Varley, S; Freeman, PANSTO’s radiocarbon capability experiences a high demand for processing groundwater samples for studies in water resource sustainability. Currently water samples are processed manually using extraction of DIC by acidification of the water and sparging with high purity helium gas (He), then cryogenic trapping of the CO₂ with recirculation of the He carrier gas to effect complete trapping of the CO₂ . This method is based on that of McNichol et al. [1]. In order to increase our capacity to extract the dissolved inorganic carbon (DIC), we are developing an automated DIC extraction system. To develop this system and test that efficacy of redesigned traps to completely capture the CO₂ without recirculation of the carrier gas, a manual test DIC line was set up to sparge acidified water with He. This line operates at ambient pressure (1 bar) and is filled with He. CO₂ gas is recovered from 50ml of the water sample by adding 5ml of 85% of phosphoric acid inside a 250ml reaction vessel. The He carrier gas is sparged at a flow rate of 30ml/min and then passed through two water traps to remove water; and two CO₂ traps to collect CO2 gas. Complete recovery of CO₂ is determined by passing the He flow through a CO₂ analyser to verify there is no presence of residual CO₂ gas. By using a temperature controller which was designed in-house the temperature of both the water trap and the CO₂ trap can be adjusted from -170°C to -60°Cwhich optimises the trapping temperature. We found that the best trapping temperatures for H₂ O and CO₂ are -110°C and -160°C, respectively. The CO₂ trapping efficiency of our system is over 99%, this was tested by trapping a CO₂ /He gas mixture containing 1mg C of CO₂ gas. The CO₂ gas is then transferred into a storage vessel until all samples on the system are processed. The CO₂ is then manually transferred to break seals for purification of the CO₂ by heating to 600°C over CuO and Ag wire. The test line has also been tested with groundwater samples. Based on the test, we are going to construct an automated DIC line in which all manual valves in the testing line will be replaced by automated valves to be controlled by computer. In addition, the water samples selector and circulation loop were designed by refer the report [2]. The system will enable the automated processing of 10 samples within 10 hours.