ORCID Profile
0000-0003-1458-824X
Current Organisation
University of Tasmania
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Publisher: Springer Science and Business Media LLC
Date: 26-08-2019
Publisher: American Scientific Publishers
Date: 12-2015
Abstract: We present a new method for the preparation of superhydrophobic materials by in situ aggregation of silica nanoparticles on a surface during a urea-formaldehyde (UF) polymerization. This is a one-step process in which a two-tier topography is obtained. The polymerization is carried out for 30, 60, 120, 180, and 240 min on silicon shards. Silicon surfaces are sintered to remove the polymer. SEM and AFM show both an increase in the area covered by the nanoparticles and their aggregation with increasing polymerization time. Chemical vapor deposition of a fluorinated silane in the presence of a basic catalyst gives these surfaces hydrophobicity. Deposition of this low surface energy silane is confirmed by the F 1s signal in XPS. The surfaces show advancing water contact angles in excess of 160 degrees with very low hysteresis (< 7) after 120 min and 60 min polymerization times for 7 nm and 14 nm silica, respectively. Depositions are successfully demonstrated on glass substrates after they are primed with a UF polymer layer. Superhydrophobic surfaces can also be prepared on unsintered substrates.
Publisher: Elsevier BV
Date: 11-2011
DOI: 10.1016/J.CHROMA.2011.09.041
Abstract: Porous graphitic carbon (PGC) particles were functionalized assivated in situ in packed beds at elevated temperature with neat di-tert-amylperoxide (DTAP) in a column oven. The performance of these particles for high performance liquid chromatography (HPLC) was assayed before and after this chemistry with the following analytes: benzene, toluene, ethyl benzene, n-propyl benzene, n-butyl benzene, p-xylene, phenol, 4-methylphenol, phenetole, 3,5-xylenol, and anisole. After the first functionalization assivation, the retention factors, k, of these compounds decreased by about 5% and the number of theoretical plates (N) increased by ca. 15%. These values of k then remained roughly constant after a second functionalization assivation but a further increase in N was noticed. In addition, after each of the reactions, the peak asymmetries decreased by ca. 15%, for a total of ca. 30%. The columns were then subjected twice to methanol at 100°C for 5h at 1 mL/min. After these stability tests, the values of k remained roughly constant, the number of plates increased, which is favorable, and the asymmetries rose and then declined, where they remained below the initial values for the unfunctionalized columns. Functionalized and unfunctionalized particles were characterized by scanning electron microscopy and BET measurements, which showed no difference between the functionalized and unfunctionalized materials, and X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry (ToF-SIMS), where ToF-SIMS suggested some chemical differences between the functionalized and unfunctionalized materials. In particular ToF-SIMS suggested that the expected five-carbon fragments from DTAP exist at higher concentrations on DTAP-functionalized PGC. First principle calculations on model graphitic surfaces suggest that the first addition of a DTAP radical to the surface proceeds in an approximately isothermal or slightly favorable fashion, but that subsequent DTAP additions are then increasingly thermodynamically favorable. Thus, this analysis suggests that the direct functionalization assivation of PGC with DTAP is plausible. Chemometric analyses of the chromatographic and ToF-SIMS data are also presented.
Publisher: Elsevier BV
Date: 10-2016
Publisher: Elsevier BV
Date: 07-2021
Publisher: American Chemical Society (ACS)
Date: 11-06-2019
DOI: 10.1021/ACS.ANALCHEM.9B01335
Abstract: Ultraviolet (UV)-light-emitting diodes (LEDs) are now widely used in analytical absorbance-based detectors as compared to conventional UV l s, they offer lower cost, faster response time, and higher photon conversion efficiency. However, current generation deep-UV-LEDs produce excess heat when operated at normal operating currents, which affects output stability and reduces their overall performance and lifespan. Herein a 3D printed liquid cooling interface has been developed for a deep-UV-LED-based optical detector, for capillary format flow-through detection. The interface consists of a circular channel that is tightly wrapped around the LED to provide active liquid cooling. The design also facilitates easy plug-and-play assembly of the various essential components of the detector: specifically, a 255 nm UV-LED, a capillary Z-cell, and a broadband UV photodiode (PD). The unique liquid cooling interface improved the performance of the detector by reducing the LED temperature up to 22 °C, increasing the spectral output up to 34%, decreasing the required stabilization time by up to 6-fold, and reducing the baseline noise and limits of detection (LODs) by a factor of 2. The detector was successfully used within a capillary HPLC system and could offer a miniaturized, rapidly stabilized, highly sensitive, and low-cost alternative to conventional UV detectors.
Publisher: American Vacuum Society
Date: 28-10-2014
DOI: 10.1116/1.4899936
Abstract: The authors report the gas phase, layer-by-layer deposition of an organosilane (N-n-butyl-aza-2,2-dimethoxysilacyclopentane, 1) and either water or aqueous ammonium hydroxide onto two substrates: Si/SiO2 and nylon. This process results in smooth, water resistant, inorganic-organic barrier layers. The layer-by-layer deposition of 1 appears to be self-limiting to a few nanometers, which may make it useful where ultrathin films of controllable dimensions and uniformity are desired. The authors are unaware of another thin film system that has these properties. Films were characterized by spectroscopic ellipsometry, water contact angle goniometry, x-ray photoelectron spectroscopy, and atomic force microscopy. Interestingly, film thicknesses on nylon were much higher than on silicon, and films prepared in the presence of the ammonia “catalyst” were thinner than those prepared with water. Test circuits coated only with a fluorosilane showed higher penetration of water compared to those coated with a barrier layer of 1/H2O and the fluorosilane.
Publisher: American Chemical Society (ACS)
Date: 31-12-2013
DOI: 10.1021/ED400401C
Publisher: Elsevier BV
Date: 04-2018
DOI: 10.1016/J.ACA.2017.12.039
Abstract: A new polymer flow-cell for chemiluminescence detection (CLD) has been designed and developed by erging multiple linear channels from a common centre port in a radial arrangement. The fabrication of radial flow-cell by 3D PolyJet printing and fused deposition modeling (FDM) has been evaluated, and compared with a similarly prepared spiral flow-cell design commonly used in chemiluminescence detectors. The radial flow-cell required only 10 h of post-PolyJet print processing time as compared to ca. 360 h long post-PolyJet print processing time required for the spiral flow-cell. Using flow injection analysis, the PolyJet 3D printed radial flow-cell provided an increase in both the signal magnitude and duration, with an average increase in the peak height of 63% and 58%, peak area of 89% and 90%, and peak base width of 41% and 42%, as compared to a coiled-tubing spiral flow-cell and the PolyJet 3D printed spiral flow-cell, respectively. Computational fluid dynamic (CFD) simulations were applied to understand the origin of the higher CLD signal obtained with the radial flow-cell design, indicating higher spatial coverage near the inlet and lower linear velocities in the radial flow-cell. The developed PolyJet 3D printed radial flow-cell was applied in a new ion chromatography chemiluminescence based assay for the detection of H
Publisher: American Chemical Society (ACS)
Date: 07-03-2013
DOI: 10.1021/LA304491X
Abstract: We describe a method for plasma cleaning silicon surfaces in a commercial tool that removes adventitious organic contamination and enhances silane deposition. As shown by wetting, ellipsometry, and XPS, hydrogen, oxygen, and argon plasmas effectively clean Si/SiO2 surfaces. However, only hydrogen plasmas appear to enhance subsequent low-pressure chemical vapor deposition of silanes. Chemical differences between the surfaces were confirmed via (i) deposition of two different silanes: octyldimethylmethoxysilane and butyldimethylmethoxysilane, as evidenced by spectroscopic ellipsometry and wetting, and (ii) a principal components analysis (PCA) of TOF-SIMS data taken from the different plasma-treated surfaces. AFM shows no increase in surface roughness after H2 or O2 plasma treatment of Si/SiO2. The effects of surface treatment with H2/O2 plasmas in different gas ratios, which should allow greater control of surface chemistry, and the duration of the H2 plasma (complete surface treatment appeared to take place quickly) are also presented. We believe that this work is significant because of the importance of silanes as surface functionalization reagents, and in particular because of the increasing importance of gas phase silane deposition.
Publisher: Elsevier BV
Date: 08-2015
DOI: 10.1016/J.IJPHARM.2015.05.081
Abstract: Electrostatic charging via contact electrification or tribocharging refers to the process of charge transfer between two solid surfaces when they are brought into contact with each other and separated. Charging of continuous particulate flows on solid surfaces is poorly understood and has often been empirical. This study aims toward understanding the tribocharging of pharmaceutical excipients using a simplified geometry of unidirectional flow in a hopper-chute assembly. Assuming electron transfer to be the dominant mechanism of electrification, a triboelectric series was generated using work functions estimated from quantum chemical calculations. A 3D-DEM model has been developed employing charge transfer and electrostatic forces. Using numerical simulations, the charge accumulation for an assemblage of particles during flow was determined under different conditions. To theoretically analyze the process of charging, parametric studies affecting powder flow have been investigated. A higher specific charge was observed at larger friction coefficients and lower restitution coefficients. The results obtained from the simulation model reinforce the collisional nature of triboelectrification. The simulation results revealed similar trends to experimental observations. However, to enable a priori prediction the model needs to be tested for additional materials or extended to other process operations.
Publisher: Elsevier BV
Date: 03-2020
Publisher: Elsevier BV
Date: 09-2012
DOI: 10.1016/J.CHROMA.2012.07.086
Abstract: Some of us recently described the fabrication of thin layer chromatography (TLC) plates from patterned carbon nanotube (CNT) forests via direct infiltration/coating of the CNTs by low pressure chemical vapor deposition (LPCVD) of silicon from SiH₄, followed by high temperature oxidation of the CNTs and Si. Herein we present an improved microfabrication process for the preparation of these TLC plates. First, a few nanometers of carbon and/or a thin film of Al₂O₃ is deposited on the CNTs. This method of priming the CNTs for subsequent depositions appears to be new. X-ray photoelectron spectroscopy confirms the presence of additional oxygen after carbon deposition. After priming, the plates are coated by rapid, conformal deposition of an inorganic material that does not require subsequent oxidation, i.e., by a fast pseudo atomic layer deposition (ψ-ALD) of SiO₂ from trimethylaluminum and tris(tert-butoxy)silanol. Unlike devices described previously, faithful reproduction of the features in the masks is still observed after oxidation. A bonded, amino phase on the resulting plates shows fast, highly efficient separations of fluorescent dyes (plate heights in the range of 1.6-7.7 μm). Extensive characterization of the new materials by TEM, SEM, EDAX, DRIFT, and XPS is reported. A substantially lower process temperature for the removal of the CNT scaffold is possible as a result of the already oxidized materials used.
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D2AN01856J
Abstract: A novel platform for direct transfer, separation, and pre-concentration of swabbed s les without elution into a solvent or a medium.
Publisher: Wiley
Date: 06-12-2013
DOI: 10.1002/SIA.5352
Publisher: Elsevier BV
Date: 11-2023
Publisher: Elsevier BV
Date: 12-2019
Publisher: American Chemical Society (ACS)
Date: 22-12-2018
DOI: 10.1021/ACS.ANALCHEM.7B03778
Abstract: Effect of column geometry on the liquid chromatographic separations using 3D printed liquid chromatographic columns with in-column polymerized monoliths has been studied. Three different liquid chromatographic columns were designed and 3D printed in titanium as 2D serpentine, 3D spiral, and 3D serpentine columns, of equal length and i.d. Successful in-column thermal polymerization of mechanically stable poly(BuMA-co-EDMA) monoliths was achieved within each design without any significant structural differences between phases. Van Deemter plots indicated higher efficiencies for the 3D serpentine chromatographic columns with higher aspect ratio turns at higher linear velocities and smaller analysis times as compared to their counterpart columns with lower aspect ratio turns. Computational fluid dynamic simulations of a basic monolithic structure indicated 44%, 90%, 100%, and 118% higher flow through narrow channels in the curved monolithic configuration as compared to the straight monolithic configuration at linear velocities of 1, 2.5, 5, and 10 mm s
Location: Australia
Start Date: 2020
End Date: 2023
Funder: Australian Research Council
View Funded ActivityStart Date: 2021
End Date: 2024
Funder: Australian Research Council
View Funded ActivityStart Date: 2021
End Date: 2025
Funder: Australian Research Council
View Funded ActivityStart Date: 2023
End Date: 2023
Funder: Australian Research Council
View Funded ActivityStart Date: 2022
End Date: 2026
Funder: Australian Research Council
View Funded Activity