ORCID Profile
0000-0002-0046-9365
Current Organisations
University of Canterbury
,
University of Western Australia
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Analytical Chemistry | Analytical Spectrometry | Physical Chemistry (Incl. Structural) | Computation Theory And Mathematics Not Elsewhere Classified | Simulation And Modelling | Nanotechnology | Structural Chemistry | Organic Chemical Synthesis | Computation Theory and Mathematics | Other Instrumental Methods | Structural Chemistry and Spectroscopy | Organic Geochemistry Not Elsewhere Classified | Supramolecular Chemistry | Physical Chemistry Not Elsewhere Classified | Physical Chemistry not elsewhere classified | Nanotechnology | Materials Engineering Not Elsewhere Classified | Soil And Water Sciences Not Elsewhere Classified | Other Information, Computing And Communication Sciences | Condensed Matter Physics—Structural Properties
ANZSRC Socio-Economic Objective (SEO)
Organic industrial chemicals not classified elsewhere | Field crops | Child health | Chemical sciences | Physical sciences | Land and water management | Human pharmaceutical products | Ceramics, glass and industrial mineral products not elsewhere classified | Computer software and services not elsewhere classified | Polymeric materials (e.g. paints) | Water services and utilities | Expanding Knowledge in the Chemical Sciences | Treatments (e.g. chemicals, antibiotics) |
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Publications
A Metabolite Profiling Approach to Identify Biomarkers of Flavonoid Intake in Humans
Publisher: Elsevier BV
Date: 12-2009
Abstract: Flavonoids are phytochemicals that are widespread in the human diet. Despite limitations in their bioavailability, experimental and epidemiological data suggest health benefits of flavonoid consumption. Valid biomarkers of flavonoid intake may be useful for estimating exposure in a range of settings. However, to date, few useful flavonoid biomarkers have been identified. In this study, we used a metabolite profiling approach to examine the aromatic and phenolic profile of plasma and urine of healthy men after oral consumption of 200 mg of the pure flavonoids, quercetin, (-)-epicatechin, and epigallocatechin gallate, which represent major flavonoid constituents in the diet. Following enzymatic hydrolysis, 71 aromatic compounds were quantified in plasma and urine at 2 and 5 h, respectively, after flavonoid ingestion. Plasma concentrations of different aromatic compounds ranged widely, from 0.01 to 10 micromol/L, with variation among volunteers. None of the aromatic compounds was significantly elevated in plasma 2 h after consumption of either flavonoid compared with water placebo. This indicates that flavonoid-derived aromatic compounds are not responsible for the acute physiological effects reported within 2 h in previous human intervention studies involving flavonoids or flavonoid-rich food consumption. These effects are more likely due to absorption of the intact flavonoid. Our urine analysis suggested that urinary 4-ethylphenol, benzoic acid, and 4-ethylbenzoic acid may be potential biomarkers of quercetin intake and 1,3,5-trimethoxybenzene, 4-O-methylgallic acid, 3-O-methylgallic acid, and gallic acid may be potential markers of epigallocatechin gallate intake. Potential biomarkers of (-)-epicatechin were not identified. These urinary biomarkers may provide an accurate indication of flavonoid exposure.
Fate of N-nitrosomorpholine in an anaerobic aquifer used for managed aquifer recharge: A column study
Publisher: Elsevier BV
Date: 04-2011
DOI: 10.1016/J.WATRES.2011.02.018
Abstract: The fate of N-nitrosomorpholine (NMOR) was evaluated at microgram and nanogram per litre concentrations. Experiments were undertaken to simulate the passage of groundwater contaminants through a deep anaerobic pyritic aquifer system, as part of a managed aquifer recharge (MAR) strategy. Sorption studies demonstrated the high mobility of NMOR in the Leederville aquifer system, with retardation coefficients between 1.2 and 1.6. Degradation studies from a 351 day column experiment and a 506 day stop-flow column experiment showed an anaerobic biologically induced reductive degradation process which followed first order kinetics. A biological lag-time of less than 3 months and a transient accumulation of morpholine (MOR) were also noted during the degradation. Comparable half-life degradation rates of 40-45 days were observed over three orders of magnitude in concentration (200 ng L(-1) to 650 μg L(-1)). An inhibitory effect on microorganism responsible to the biodegradation of NMOR at 650 μg L(-1) or a threshold effect at 200 ng L(-1) was not observed during these experiments.
Photoelectron Spectroscopy and High-Level Ab Initio Calculations of the Iodide–Methylperoxy Radical Complex
Publisher: American Chemical Society (ACS)
Date: 12-05-2022
Abstract: Anion photoelectron spectroscopy has been used to investigate the structure and dynamics of CH
The synthesis of fluorescent DNA intercalator precursors through efficient multiple heck reactions
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/CH10374
Abstract: A highly efficient synthesis of p-carboethoxy-tristyryl and carboethoxy-terastyrenyl benzene derivatives through a multiple Heck cross coupling reaction is reported. This reaction provides an efficient route to DNA intercalator precursors containing a benzene core.
Quercetin and its in vivo metabolites inhibit neutrophil-mediated low-density lipoprotein oxidation
Publisher: American Chemical Society (ACS)
Date: 05-2008
DOI: 10.1021/JF8003042
Abstract: This study examined the effects of metabolic transformation of the common dietary flavonoid, quercetin, on its ability to protect low-density lipoprotein (LDL) from neutrophil-mediated modification. Quercetin was shown to be effective in protecting LDL against neutrophil-mediated modification at physiological concentrations (1 microM) and appears to act by inhibiting myeloperoxidase (MPO)-catalyzed oxidation (IC(50) = 1.0 microM). Quercetin was also shown to protect against radical-induced [2,2'-azobis(2-methylpropionamidine)dihydrochloride] oxidation (IC(50) = 1.5 microM). Studies of structure-activity relationships showed that methylation at the 3'-position or glucuronidation at the 3-position did not significantly affect inhibition by quercetin of the MPO activity, but conjugations at both positions significantly reduce its activity. Our results suggest that the common dietary flavonoid, quercetin, and some of its major in vivo metabolites are potential inhibitors of MPO at physiological concentrations. Dietary flavonoids that could modify MPO activity could protect lipoproteins from damage in chronic inflammatory states such as cardiovascular disease.
Metabolic transformation has a profound effect on anti-inflammatory activity of flavonoids such as quercetin: Lack of association between antioxidant and lipoxygenase inhibitory activity
Publisher: Elsevier BV
Date: 03-2008
DOI: 10.1016/J.BCP.2007.11.002
Abstract: Dietary flavonoids are thought to have health benefits possibly due to antioxidant and anti-inflammatory properties. Many previous in vitro studies examining the bioactivity of flavonoids have failed to consider the effects of metabolic transformation on flavonoid activity. In this study we examined the effect of quercetin and its major metabolites on the production of pro-inflammatory eicosanoids by human leukocytes. Studies comparing free radical scavenging, antioxidant activity and eicosanoid production demonstrate that there are different structural requirements for antioxidant and anti-inflammatory activity. We also investigated the effect of metabolic transformation on flavonoid bioactivity by comparing the activity of quercetin and its major metabolites to inhibit inflammatory eicosanoid production from human leukocytes. Quercetin was a potent inhibitor of leukotriene B4 formation in leukocytes (IC50 approximately 2 microM), and its activity was dependent on specific structural features, particularly the 2,3-double bond of the C-ring. Functionalisation of the 3'-OH group with either methyl or sulfate reduced inhibitory activity up to 50% while a glucuronide substituent at the 3-OH effectively removed the LTB4 inhibitory activity. The major quercetin metabolite quercetin-3'-O-sulfate retained considerable lipoxygenase inhibitory activity (IC50 approximately 7 microM) while quercetin-3-O-glucuronide maintained antioxidant activity but had no lipoxygenase inhibitory activity at physiological concentrations. In conclusion, we have found that structural modification of quercetin due to metabolic transformation had a profound effect on bioactivity, and that the structural features required for antioxidant activity of quercetin and related flavonoids were unrelated to those required for inhibition of inflammatory eicosanoids.
The CH3CHOO 'Criegee intermediate' and its anion: Isomers, infrared spectra, and W3-F12 energetics
Publisher: Elsevier BV
Date: 02-2015
Photoelectron Spectroscopy and Structures of X−⋅⋅⋅CH2O (X=F, Cl, Br, I) Complexes
Publisher: Wiley
Date: 12-2020
SYNTHESIS AND LANGMUIR-BLODGETT-FILM PROPERTIES OF SOME BIFUNCTIONAL TTF DERIVATIVES
Publisher: Elsevier BV
Date: 10-1992
Understanding biofouling and contaminant accretion on submerged marine structures
Publisher: Springer Science and Business Media LLC
Date: 21-06-2023
DOI: 10.1038/S41529-023-00370-5
Abstract: Fouling of maritime infrastructure is pervasive due to abundant biological and chemical activity within the oceanic environment. Marine biofilms and their successional growths are prevalent issues in biofouling, but current industrial and research-based analyses often do not provide a holistic view of the fouling bio ersity. Cathodic protection is a longstanding system safeguarding infrastructure from the corrosive marine environment, but limited studies on interactions between biological growth and cathodic activity have been conducted in the context of marine fouling. This review identifies knowledge gaps in the understanding of marine fouling and highlights approaches to better direct development of effective anti-fouling measures.
The simplest sulfur-nitrogen hydrogen bond: matrix isolation spectroscopy of H2S·NH3
Publisher: Elsevier BV
Date: 04-2021
Solution photochemistry of poly(dialkylsilanes)
Publisher: Walter de Gruyter GmbH
Date: 1988
Infrared Identification of Matrix Isolated H2O·O2
Publisher: American Chemical Society (ACS)
Date: 21-04-2005
DOI: 10.1021/JP050040V
Abstract: Theoretical studies of the H2O.O2 complex have been carried out over the past decade, but the complex has not previously been experimentally identified. We have assigned IR vibrations from an H2O.O2 complex in an inert rare gas matrix. This identification is based upon theoretical calculations and concentration dependent behavior of absorption bands observed upon co-deposition of H2O and O2 in argon matrixes at 11.5 +/- 0.5 K. To aid assignment, we have used a harmonically coupled anharmonic oscillator local mode model with an ab initio calculated dipole moment function to calculate the OH-stretching and HOH-bending frequencies and intensities in the complex. The high abundance of H2O and O2 makes the H2O.O2 complex likely to be significant in atmospheric and astrophysical chemistry.
ELECTRON-SPIN-RESONANCE INVESTIGATION OF SC2+ IN NEON MATRICES AND ASSIGNMENT OF ITS GROUND ELECTRONIC-STATE AS X(4)SIGMA- - COMPARISON WITH THEORETICAL CALCULATIONS
Publisher: AIP Publishing
Date: 15-11-1993
DOI: 10.1063/1.465718
Abstract: The discandium radical cation, Sc+2, has been isolated in neon matrices at 4 K and studied by electron spin resonance (ESR) spectroscopy and theoretical methods. It was produced by the x-irradiation of neon matrix s les containing neutral Sc2 which was formed by trapping the products generated from the pulsed laser vaporization of scandium metal. The experimental and theoretical findings indicate that Sc+2 has a 4Σ−g electronic ground state compared to an X 5Σ−u state for the neutral discandium radical. The large decrease in the 45Sc hyperfine interaction (A tensor) going from Sc2 to Sc+2 provides direct experimental information concerning the types of valence molecular orbitals that are involved in these diatomic radicals. The neon matrix magnetic parameters for 45Sc+2 are g∥≊2.00, g⊥=1.960(1), ‖A∥‖=28(6), and ‖A⊥‖=26.1(3) MHz the D value (zero field splitting) was 15 381(3) MHz. Ab initio configuration interaction (CI) calculations of the nuclear hyperfine interactions yielded results in reasonable agreement with the experimental observations.
Benzotriazole and 5-methylbenzotriazole in recycled water, surface water and dishwashing detergents from Perth, Western Australia: analytical method development and application
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4EM00484A
Abstract: A simplified analytical method was developed and used to assess the occurrence of benzotriazole and 5-methyl benzotriazole and removal rates in various Western Australian environmental water s les.
ELECTRON-SPIN-RESONANCE STUDIES OF P2H6+ AND PH3+ RADICAL CATIONS IN RARE-GAS MATRICES AT 4-K - COMPARISON WITH THEORETICAL CALCULATIONS
Publisher: AIP Publishing
Date: 15-11-1993
DOI: 10.1063/1.465719
Abstract: Detailed experimental and theoretical electron spin resonance (ESR) studies of the cation radicals, PH+3 and P2H+6, isolated in neon and argon matrices are reported. These cations were generated by photoionization (17 eV) and x-irradiation (80 keV) methods. The observed nuclear hyperfine interactions (A tensors) showed reasonable agreement with Aiso and Adipolar values calculated at the ab initio configuration interaction (CI) level. These ESR results for PH+3 clearly indicate its nonplanarity for P2H+6, an earlier theoretical prediction of a C2h distortion from C3v was confirmed by these new experimental results which reveal two different H atom environments. The neon magnetic parameters for PH+3 are g∥=2.002(1), g⊥=2.007(1), A⊥=920(3), and A∥=1638(15) MHz for 31P and A(H)≤6 MHz. The neon parameters for P2H+6 are g∥=2.001(1), g⊥=2.003(1), A⊥=1527(2), and A∥=1909(4) MHz for 31P and A(2H)=182(2) and A(4H)=±22(2) MHz.
Neon Matrix Isolation Electron Spin Resonance and Theoretical studies of the Various Isotopomers of the CH3Mg Radical
Publisher: American Chemical Society (ACS)
Date: 13-09-2000
DOI: 10.1021/JP001773C
Specific Dietary Polyphenols Attenuate Atherosclerosis in Apolipoprotein E-Knockout Mice by Alleviating Inflammation and Endothelial Dysfunction
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 04-2010
DOI: 10.1161/ATVBAHA.109.199687
Abstract: Objective— Animal and clinical studies have suggested that polyphenols in fruits, red wine, and tea may delay the development of atherosclerosis through their antioxidant and anti-inflammatory properties. We investigated whether in idual dietary polyphenols representing different polyphenolic classes, namely quercetin (flavonol), (−)-epicatechin (flavan-3-ol), theaflavin (dimeric catechin), sesamin (lignan), or chlorogenic acid (phenolic acid), reduce atherosclerotic lesion formation in the apolipoprotein E (ApoE) −/− gene–knockout mouse. Methods and Results— Quercetin and theaflavin (64-mg/kg body mass daily) significantly attenuated atherosclerotic lesion size in the aortic sinus and thoracic aorta ( P .05 versus ApoE −/− control mice). Quercetin significantly reduced aortic F 2 -isoprostane, vascular superoxide, vascular leukotriene B 4 , and plasma-sP-selectin concentrations and augmented vascular endothelial NO synthase activity, heme oxygenase-1 protein, and urinary nitrate excretion ( P .05 versus control ApoE −/− mice). Theaflavin showed similar, although less extensive, significant effects. Although (−)-epicatechin significantly reduced F 2 -isoprostane, superoxide, and endothelin-1 production ( P .05 versus control ApoE −/− mice), it had no significant effect on lesion size. Sesamin and chlorogenic acid treatments exerted no significant effects. Quercetin, but not (−)-epicatechin, significantly increased the expression of heme oxygenase-1 protein in lesions versus ApoE −/− controls. Conclusion— Specific dietary polyphenols, in particular quercetin and theaflavin, may attenuate atherosclerosis in ApoE −/− gene–knockout mice by alleviating inflammation, improving NO bioavailability, and inducing heme oxygenase-1. These data suggest that the cardiovascular protection associated with diets rich in fruits, vegetables, and some beverages may in part be the result of flavonoids, such as quercetin.
A matrix isolation ESR and theoretical study of MgN
Publisher: AIP Publishing
Date: 27-07-2017
DOI: 10.1063/1.4993794
Abstract: Matrix isolation experiments have been conducted on the Mg14N, 25Mg14N, Mg15N, and 25Mg15N radicals which were formed by the reaction of a plume of magnesium metal produced with laser ablation and either acetonitrile vapour or nitrogen atoms. The radicals were isolated in an inert neon matrix at 4.3 K and studied with electron spin resonance spectroscopy. The ground electronic state of MgN was determined to be 4Σ−. The following magnetic parameters were determined experimentally for MgN: g⊥ = 2.004 78 (2), g∥ = 2.001 72 (4), |D| = 9797 (6) MHz, A⊥(14N) = 19.7 (2) MHz, A∥ (14N) = −4.0 (3) MHz, A⊥(15N) = 27.5 (3) MHz, A∥ (15N) = −5.7 (3) MHz, A⊥ (25Mg) = −60.7 (5) MHz, and A∥(25Mg) = −65 (3) MHz. The low-lying electronic states of MgN were also investigated using the complete active space multiconfigurational self-consistent field technique. By plotting the potential energy surface, theoretical parameters for the ground state with a configuration of 5σ26σ27σ12π12π1 were able to be determined, including re = 2.090 Å and De = 11.28 kcal/mol.
The bromide-bromomethyl radical dimer complex: Anion photoelectron spectroscopy and CCSD(T) calculations
Publisher: Elsevier BV
Date: 12-2020
Optical and photocatalytic properties of nanocrystalline TiO2 synthesised by solid-state chemical reaction
Publisher: Elsevier BV
Date: 12-2007
Oxidized adrenodoxin acts as a competitive inhibitor of cytochrome P450scc in mitochondria from the human placenta
Publisher: Wiley
Date: 15-04-2001
DOI: 10.1046/J.1432-1327.2001.02113.X
Abstract: The conversion of cholesterol to pregnenolone by cytochrome P450scc is the rate-determining step in placental progesterone synthesis. The limiting component for placental cytochrome P450scc activity is the concentration of adrenodoxin reductase in the mitochondria, where it permits cytochrome P450scc to work at only 16% of maximum velocity. Adrenodoxin reductase serves to reduce adrenodoxin as part of the electron transfer from NADPH to cytochrome P450scc. We therefore measured the proportion of adrenodoxin in the reduced form in intact mitochondria from the human placenta during active pregnenolone synthesis, using EPR. We found that the adrenodoxin pool was only 30% reduced, indicating that the adrenodoxin reductase concentration was insufficient to maintain the adrenodoxin in the fully reduced state. As both oxidized and reduced adrenodoxin can bind to cytochrome P450scc we tested the ability of oxidized adrenodoxin to act as a competitive inhibitor of pregnenolone synthesis. This was done in a fully reconstituted system comprising 0.3% Tween 20 and purified proteins, and in a partially reconstituted system comprising submitochondrial particles, purified adrenodoxin and adrenodoxin reductase. We found that oxidized adrenodoxin is an effective competitive inhibitor of placental cytochrome P450scc with a Ki value half that of the Km for reduced adrenodoxin. We conclude that the limiting concentration of adrenodoxin reductase present in placental mitochondria has a two-fold effect on cytochrome P450scc activity. It limits the amount of reduced adrenodoxin that is available to donate electrons to cytochrome P450scc and the oxidized adrenodoxin that remains, competitively inhibits the cytochrome.
Matrix isolated HgCH3 radical: An ESR investigation
Publisher: American Chemical Society (ACS)
Date: 30-04-2004
DOI: 10.1021/JP0400925
Towards an Understanding of Halide Interactions with the Carbonyl‐Containing Molecule CH3CHO
Publisher: Wiley
Date: 10-06-2021
Abstract: The anion photoelectron spectra of Cl − ⋅⋅⋅CD 3 CDO, Cl − ⋅⋅⋅(CD 3 CDO) 2 , Br − ⋅⋅⋅CH 3 CHO, and I − ⋅⋅⋅CH 3 CHO are presented with electron stabilisation energies of 0.55, 0.93, 0.48, and 0.40 eV, respectively. Optimised geometries of the singly solvated species featured the halide appended to the CH 3 CHO molecule in‐line with the electropositive portion of the C=O bond and having binding energies between 45 and 52 kJ mol −1 . The doubly solvated Cl − ⋅⋅⋅(CH 3 CHO) 2 species features asymmetric solvation upon the addition of a second CH 3 CHO molecule. Theoretical detachment energies were found to be in excellent agreement with experiment, with comparisons drawn between other halide complexes with simple carbonyl molecules.
Anion photoelectron spectroscopy and high level ab initio calculations of the halide-acetylene dimer complexes
Publisher: Elsevier BV
Date: 2015
Halide–propene complexes: validated DSD-PBEP86-D3BJ calculations and photoelectron spectroscopy
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2CP03796C
Abstract: Anion photoelectron spectroscopy has been used to determine the electron binding energies of the X − ⋯C 3 H 6 (X = Cl, Br, I) complexes.
Optical and photocatalytic properties of nanoparticulate (TiO2)χ(ZnO)1-χ powders
Publisher: Elsevier BV
Date: 2010
A comparative evaluation of the photocatalytic and optical properties of nanoparticulate ZnO synthesised by mechanochemical processing
Publisher: Springer Science and Business Media LLC
Date: 13-06-2008
The production of oxidants in Europa's surface
Publisher: Mary Ann Liebert Inc
Date: 12-2003
DOI: 10.1089/153110703322736123
Abstract: The oxidants produced by radiolysis and photolysis in the icy surface of Europa may be necessary to sustain carbon-based biochemistry in Europa's putative subsurface ocean. Because the subduction of oxidants to the ocean presents considerable thermodynamic challenges, we examine the formation of oxygen and related species in Europa's surface ice with the goal of characterizing the chemical state of the irradiated material. Relevant spectral observations of Europa and the laboratory data on the production of oxygen and related species are first summarized. Since the laboratory data are incomplete, we examine the rate equations for formation of oxygen and its chemical precursors by radiolysis and photolysis. Measurements and simple rate equations are suggested that can be used to characterize the production of oxidants in Europa's surface material and the chemical environment produced by radiolysis. Possible precursor molecules and the role of radical trapping are examined. The possibility of oxygen reactions on grain surfaces in Europa's regolith is discussed, and the earlier estimates of the supply of O(2) to the atmosphere are increased.
In situ chemical analysis of modern organic tattooing inks and pigments by micro-Raman spectroscopy
Publisher: Wiley
Date: 04-04-2008
DOI: 10.1002/JRS.1973
Halides and the carbon-carbon double bond: Interactions of ethylene with bromide and iodide
Publisher: Elsevier BV
Date: 04-2022
Characterisation of gas phase halide-acetone complexes with photoelectron spectroscopy and ab initio calculations
Publisher: Elsevier BV
Date: 10-2019
NEW CONDUCTING POLYMERS - PF6-DOPED XYZ-TRIHETEROCYCLES BASED ON X,Y, Z= THIOPHENE, FURAN AND N-METHYLPYRROLE
Publisher: Elsevier BV
Date: 03-1993
A BODY-DIAGONAL BOND IN CUBANE - CAN IT BE INTRODUCED
Publisher: American Chemical Society (ACS)
Date: 1990
DOI: 10.1021/JA00158A061
Luminescent Photoproducts in UV-Irradiated Ice
Publisher: American Chemical Society (ACS)
Date: 27-06-2000
DOI: 10.1021/AR990145E
Abstract: This Account describes the near-UV and visible luminescences emitted from crystalline, polycrystalline, and amorphous ices as a result of excitation by UV light. Vibrationally resolved, short-lived luminescence around 340 nm arises from excited O(2) formed by the reaction of two O atoms. Long-lived luminescence around 420 nm is tentatively assigned to a spin-forbidden (4)sigma(-) --> X(2)Pi transition of OH. This Account gives a history of the research into this little-known phenomenon, places it in the context of other spectroscopic studies of gaseous and solid water, and proposes future directions for the work.
A comparison of solvent extract cleanup procedures in the analysis of organic explosives
Publisher: Wiley
Date: 27-12-2013
Abstract: The use of an organic solvent to extract explosive residues from hand swabs and postblast debris inevitably leads to the coextraction of unwanted materials, usually in far greater quantities than any explosive residue. In this study, the extraction efficiency of a number of solvent cleanup procedures including solid-phase extraction (SPE), adsorbent resins such as Chromosorb-104, and traditional materials such as silica and Florisil was calculated using a quantitative liquid chromatography-ultraviolet (LC-UV) detection procedure. The Oasis(®) HLB cartridge outperformed other cleanup procedures, with analyte recoveries approaching 95%, while the Amberlite XAD-7 procedure returned the lowest overall recoveries. The matrix rejection ability of each method was then determined using a simulated highly contaminated matrix, with the adsorbent resins showing a higher degree of matrix rejection, which is seen as a reduction in background noise in the UV chromatogram using 210 nm detection.
Augmentation of monocyte intracellular ascorbate in vitro protects cells from oxidative damage and inflammatory responses
Publisher: Elsevier BV
Date: 07-2006
DOI: 10.1016/J.BBRC.2006.04.174
Abstract: Ascorbic acid is present as a primary antioxidant in plasma and within cells, protecting both cytosolic and membrane components of cells from oxidative damage. The effects of intracellular ascorbic acid on F(2)-isoprostanes (biomarkers of oxidative stress) and monocyte chemoattractant protein-1 (marker of inflammatory responses) production in monocytic THP-1 cells were investigated under conditions of 2,2'-Azobis(2-methylpropionamidine)dihydrochloride (AAPH) induced oxidative stress. Cells cultured under normal conditions have extremely low ascorbate levels and the intracellular ascorbate can be augmented significantly by adding ascorbate to the culture medium. While AAPH treatment reduced cell viability, increased F(2)-isoprostanes and MCP-1 production, the presence of intracellular ascorbic acid maintained high cell viability and attenuated both F(2)-isoprostanes and MCP-1 production. Measurement of intracellular ascorbic acid and its oxidised products showed that intracellular ASC was oxidised to a significantly greater extent during AAPH treatment and may be utilised to protect the cells under conditions of oxidative stress. This study demonstrates the importance of intracellular ascorbate, which may be lacking under normal cell culture conditions, under conditions of increased oxidative stress.
Breath Level Acetone Discrimination Through Temperature Modulation of a Hierarchical ZnO Gas Sensor
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 10-2017
LASER VAPORIZATION GENERATION OF THE SIB AND SIAL RADICALS FOR MATRIX-ISOLATION ELECTRON-SPIN-RESONANCE STUDIES - COMPARISON WITH THEORETICAL CALCULATIONS AND ASSIGNMENT OF THEIR ELECTRONIC GROUND-STATES AS X (4)SIGMA
Publisher: AIP Publishing
Date: 05-1993
DOI: 10.1063/1.464767
Abstract: The first experimental spectroscopic study of the SiB and SiAl diatomic radicals is reported. Electron spin resonance results indicate that both molecules have X 4Σ ground electronic states, in agreement with earlier theoretical calculations. The SiB and SiAl radicals were generated in neon matrices at 4 K by trapping the products produced from the pulsed laser vaporization of their alloys. Electronic structure information for these radicals is especially interesting given the utilization of silicon doped materials in semiconductor applications. The observed nuclear hyperfine interactions (A tensors) for 10B, 11B, and 27Al in these molecular radicals were compared with the results of ab initio configuration-interaction theoretical calculations which were conducted as part of this experimental study. The neon matrix magnetic parameters (MHz) for Si 11B are D=800(2), g∥=2.0014(8), g⊥=2.0005(4), A⊥=92.4(5), and A∥=111(2). For Si 27Al the results (MHz) are D=9710(2), g∥=1.9994(8), and g⊥=1.9978(4), ‖A⊥‖=10.3(6), and ‖A∥‖=43.5(8).
Theoretical and neon matrix electron spin resonance studies of the methanol cation: CH3OH+, CH3OD+, CH2DOH+, and 13CH3OH+
Publisher: AIP Publishing
Date: 15-10-1992
DOI: 10.1063/1.463796
Abstract: Four isotopes of the methanol cation radical (CH3OH+) have been generated by three independent methods and isolated in neon matrices at 4 K for a detailed electron spin resonance (ESR) investigation. The ion generation methods employed were X irradiation, photoionization, and electron ionization. The nuclear hyperfine (A tensors) measurements were compared with those obtained from ab initio extended basis set multireference configuration interaction (CI) wave functions. The relationships between geometry and electronic structures were fully explored. The trend in the large isotropic methyl hydrogen A values for the isoelectronic series CH3F+, CH3OH+, and CH3NH2+ was found to follow the trend in dissociation energies for these radical cations. The neon magnetic parameters for CH3OH+ are gx=2.0036(4) and gz=2.010(1) Aiso (methyl hydrogens)=229(1) MHz, ‖Ax‖=54(2) and ‖Az‖=80(3) MHz for the hydroxy hydrogen ‖Ax‖=40(2) and ‖Az‖=29(4) MHz for 13C. The observed magnetic parameters for CH2DOH+ indicate an unusually large deuterium effect Aiso (CH2)=329 MHz with ‖Aiso‖=4.1(3) MHz for the methyl deuterium. These results show that averaging of the methyl hydrogen environments is occurring on the ESR time scale.
Temperature Dependence of the Visible-Near-Infrared Absorption Spectrum of Liquid Water
Publisher: American Chemical Society (ACS)
Date: 08-09-2001
DOI: 10.1021/JP010093M
Origin of a mixed brominated ethene groundwater plume: Contaminant degradation pathways and reactions
Publisher: American Chemical Society (ACS)
Date: 12-01-2007
DOI: 10.1021/ES0615674
Abstract: On the basis of a combination of laboratory microcosm experiments, column sorption experiments, and the current spatial distribution of groundwater concentrations, the origin of a mixed brominated ethene groundwater plume and its degradation pathway were hypothesized. The contaminant groundwater plume was detected downgradient of a former mineral processing facility, and consisted of tribromoethene (TriBE), cis-1,2-dibromoethene (c-DBE), trans-1,2-dibromoethene (t-DBE), and vinyl bromide (VB). The combined laboratory and field data provided strong evidence that the origin of the mixed brominated ethene plume was a result of dissolution of the dense non-aqueous-phase liquid 1,1,2,2-tetrabromoethane (TBA) atthe presumed source zone, which degraded rapidly (half-life of 0.2 days) to form TriBE in near stoichiometric amounts. TriBE then degraded (half-life of 96 days) to form c-DBE, t-DBE, and VB via a reductive debromination degradation pathway. Slow degradation of c-DBE (half-life >220 days), t-DBE (half-life 220 days), and VB (half-life >220 days) coupled with their low retardation coefficients (1.2, 1.2, and 1.0 respectively) resulted in the formation of an extensive mixed brominated ethene contaminant plume. Without this clearer understanding of the mechanism for TBA degradation, the origin of the mixed brominated ethene groundwater contamination could have been misinterpreted, and inappropriate and ineffective source zone and groundwater remediation techniques could be applied.
Benzotriazoles in the Aquatic Environment: A Review of Their Occurrence, Toxicity, Degradation and Analysis
Publisher: Springer Science and Business Media LLC
Date: 30-06-2015
Molecules of life: studying the interaction between water and phosphine in argon matrices
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2CP03434D
Abstract: The interaction between water and phosphine isolated in solid argon matrices has been investigated.
Effect of particle size on the photocatalytic activity of nanoparticulate zinc oxide
Publisher: Springer Science and Business Media LLC
Date: 02-2006
Cover Feature: Spectroscopic Investigation of Chalcogen Bonding: Halide–Carbon Disulfide Complexes (ChemPhysChem 9/2021)
Publisher: Wiley
Date: 05-05-2021
Zero valent iron remediation of a mixed brominated ethene contaminated groundwater
Publisher: Elsevier BV
Date: 2009
DOI: 10.1016/J.JCONHYD.2008.09.010
Abstract: The suitability of a granulated zero valent iron (ZVI) permeable reactive barrier (PRB) remediation strategy was investigated for tribromoethene (TriBE), cis-1,2-dibromoethene (c-DBE), trans-1,2-dibromoethene (t-DBE) and vinyl bromide (VB), via batch and large-scale column experiments that were subsequently analysed by reactive transport modelling. The brominated ethenes in both batch and large-scale column experiments showed rapid (compared to controls and natural attenuation) degradation in the presence of ZVI. In the large-scale column experiment, degradation half-lives were 0.35 days for TriBE, 0.50 days for c-DBE, 0.31 days for t-DBE and 0.40 days for VB, under site groundwater flow conditions, resulting in removal of brominated ethenes within the first 0.2 m of a 1.0 m thick ZVI layer, indicating that a PRB groundwater remediation strategy using ZVI could be used successfully. In the model simulations of the ZVI induced brominated ethene degradation, assuming a dominant reductive beta-elimination pathway via bromoacetylene and acetylene production, simulated organic compound concentrations corresponded well with both batch and large-scale column experimental data. Changes of inorganic reactants were also well captured by the simulations. The similar ZVI induced degradation pathway of TriBE and TCE suggests that outcomes from research on ZVI induced TCE remediation could also be applied to TriBE remediation.
Anion Photoelectron Spectroscopy and High Level Ab Initio Calculations of the Halide-Nitric Oxide Dimer Complexes
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/CH17581
Abstract: Anion photoelectron spectra are presented for gas phase complexes formed between halide anions and nitric oxide, X−⋯NO where X− = Cl−, Br−, and I−. Electron binding energies are experimentally determined to be 3.82, 3.51, and 3.17 eV. Results from CCSD(T)/aug-cc-pVTZ calculations are presented for the anion species, whereby a single minimum of Cs symmetry is predicted. Binding energies (D0) of 15.3, 13.3, and 11.7 kJ mol−1 are predicted from complete basis set limit extrapolation, and are found to be in line with previous experimental studies.
Mechanochemical synthesis of nanocrystalline SnO2-ZnO photocatalysts
Publisher: IOP Publishing
Date: 06-01-2006
Identification of H2O¿HO in Argon Matrices
Publisher: American Chemical Society (ACS)
Date: 12-2000
DOI: 10.1021/JA003337+
LASER VAPORIZATION GENERATION OF THE DIATOMIC RADICALS PDB, (PDB)-PD-105, PDAL, AND (PDAL)-PD-105 - ELECTRON-SPIN-RESONANCE INVESTIGATION IN NEON MATRICES AT 4-K
Publisher: AIP Publishing
Date: 09-1992
DOI: 10.1063/1.463040
Abstract: The new diatomic radicals PdB and PdAl have been generated by depositing the products produced from the pulsed laser vaporization of the elemental mixtures into neon matrices at 4 K. ESR (electron spin resonance) studies of these matrix isolated radicals, including an analysis of the 105Pd(I=5/2), 27Al(I=5/2), and 11B(I=3/2) nuclear hyperfine interactions, show that both have X 2Σ electronic ground states. These new results are compared with previous ESR measurements for PdH, PdCH3, YPd, ScPd, and PdH2+ to reveal electronic structure information and bonding trends as the complexity of the ligand increases 1s, 2p, 3p, 3d, and 4d. Ab initio UHF (unrestricted Hartree–Fock) theoretical calculations were also conducted on four of these small palladium radicals as part of this experimental investigation. A simple interpretation of the 105Pd hyperfine interactions and molecular g tensors based on the degree of charge transfer to palladium is presented. The observed magnetic parameters (MHz) for 105Pd11B in a neon matrix at 4 K are g∥=2.009(2), g⊥=2.042(2), A∥=−1483(15), and A⊥=−1483(2) for 105Pd, and A∥=197(4) and A⊥=140(1) for 11B. The parameters for 105Pd27Al are g∥=2.010(1), g⊥=2.0343(5), A∥=−1283(10) and A⊥=−1268(2) for 105Pd, and A∥=182(2) and A⊥=84.6(5) for 27Al.
Evidence For a Water-Stabilised Ion Radical Complex: Photoelectron Spectroscopy and Ab Initio Calculations
Publisher: CSIRO Publishing
Date: 2020
DOI: 10.1071/CH19428
Abstract: A photoelectron spectrum corresponding to an unknown 174m/z anion complex has been recorded. Initially believed to be I−…CH3CH2OH (173m/z), the spectrum has been assigned as belonging to that of an I−…H2O…CH3CH2 radical anion complex. The major peaks in the photoelectron spectrum occur at 3.54eV and 4.48eV as the 2P3/2 and 2P1/2 spin-orbit states of iodine respectively. Ab initio calculations were performed in order to rationalise the existence of the complex, with all structures converging to a ‘ring-like’ geometry, with the iodide anion bound to both the water molecule as well as a hydrogen of the ethyl radical, with the other hydrogen of water bound to the unpaired electron site of the ethyl. Simulated vertical detachment energies of 3.59eV and 4.53eV were found to be in agreement with the experimental results.
The Structure of CCl5– in the Gas Phase
Publisher: American Chemical Society (ACS)
Date: 22-08-2019
DOI: 10.1021/ACS.JPCLETT.9B02242
Abstract: The first experimental evidence of the structure of the CCl
Magnetic studies of metal ion coordination clusters encapsulated with thiacalixarene
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/CH14136
Abstract: Three thiacalix[4]arene polynuclear complexes have been prepared by literature methods for detailed magnetic investigation. The [Fe3O(L)2] (LH4 = thiacalix[4]arene) complex is found to exhibit interesting anti-ferromagnetic exchange coupling. Jahn–Teller distortion in [Cu4(L)2] complex leads to strong anti-ferromagnetic coupling at low temperatures. The temperature-dependent susceptibility of the [(μ-H2O)Eu2(LH)2(DMF)4] complex is well described by a ground state involving the thermal population of the lowest three excited states.
Matrix Isolation ESR and Theoretical Study of ZnN
Publisher: American Chemical Society (ACS)
Date: 04-2019
Abstract: The Zn
ELECTRON-SPIN-RESONANCE AND THEORETICAL-STUDIES OF THE PO2 AND ASO2 RADICALS IN NEON MATRICES AT 4 K - LASER VAPORIZATION AND X-IRRADIATION RADICAL GENERATION TECHNIQUES
Publisher: AIP Publishing
Date: 08-07-1995
DOI: 10.1063/1.470135
Abstract: The utilization of high energy generation techniques for trapping ion radicals and other reactive intermediates in neon matrices at 4 K is discussed. Electron spin resonance (ESR) results for several small radicals are presented to demonstrate the application of x irradiation and reactive laser vaporization for neon matrix isolation studies. Detailed ESR studies of the PO2 and AsO2 radicals, along with ab initio theoretical computations of their nuclear hyperfine interactions, are presented. No previous ESR observations have been reported for these radicals, although PO2 has been studied under high resolution in the gas phase utilizing far-infrared laser magnetic resonance and microwave spectroscopies.
Halide-Nitrogen Gas-Phase Clusters: Anion Photoelectron Spectroscopy and High Level ab Initio Calculations
Publisher: American Chemical Society (ACS)
Date: 09-2015
Abstract: The gas phase anion photoelectron spectra are presented for the halide-nitrogen clusters X(-)···(N2)n, where X = Br and I and n ≤ 5. Electron binding energies for each cluster in the halide series are determined, with no evidence observed for first solvation shell closure in either series. High level ab initio calculations at the CCSD(T) level of theory are presented for the anion and neutral halogen-nitrogen complexes. For the anion species, two minima are predicted corresponding to a loosely bound C2v "T-shaped" species and to a higher energy covalently bound "triangle" C2v symmetry geometry. For the neutral species, three stationary points were located, two of which display similar form to the anion minima and a third which is linear, i.e., C∞v symmetry. The "T-shaped" geometry is a transition state linking equivalent C∞v symmetry minima. Cluster dissociation energies (D0) were determined, for both anion and neutral global minima at the CCSD(T) complete basis set limit, to be 7.8 kJ mol(-1) and 7.0 kJ mol(-1) and 3.5 kJ mol(-1) and 5.0 kJ mol(-1) for the bromine and iodine species, respectively.
Mechanochemical synthesis of nanoparticulate ZnO-ZnWO4 powders and their photocatalytic activity
Publisher: Elsevier BV
Date: 2009
An investigation into the fate of organic explosives in soil
Publisher: Informa UK Limited
Date: 03-2013
EPR-ENDOR SPECTROSCOPY OF MATRIX-ISOLATED NH3+ AND CH3 RADICALS
Publisher: American Chemical Society (ACS)
Date: 04-1991
DOI: 10.1021/J100160A011
Identification of the Water Amidogen Radical Complex
Publisher: American Chemical Society (ACS)
Date: 12-01-2009
DOI: 10.1021/JA808109M
Abstract: The water amidogen radical complex (H(2)O-NH(2)) is a reactive intermediate in the atmospheric oxidation of ammonia by a hydroxyl radical. In the present study, we identify for the first time the H(2)O-NH(2) complex using matrix isolation infrared spectroscopy. We corroborate our experimental findings with high level coupled cluster ab initio calculations.
A fast liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF-MS) method for the identification of organic explosives and propellants
Publisher: Elsevier BV
Date: 12-2013
DOI: 10.1016/J.FORSCIINT.2013.08.007
Abstract: A fast, highly specific and sensitive method for the detection of an extensive list of organic explosives and propellants using an optimised Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometry (LC-QToF-MS) procedure has been developed. Analyte specific information including retention time, adduct accurate mass and fragmentation data was firstly collected using both positive and negative ion Atmospheric Pressure Chemical Ionisation (APCI) and entered into a Personal Compound Database/Library (PCDL). The custom PCDL can then be used to screen any s le for the presence of organic explosives and propellants, generating a match score for any identified compounds. To date over 50 organic explosives and propellants have been characterised and entered into the database representing those likely to be encountered in forensic and environmental s les and also a range of specialist explosives.
Anion Photoelectron Spectra and Ab Initio Calculations of the Iodide-Carbon Monoxide Clusters: I¯ ···(CO)n, n=1-4
Publisher: American Chemical Society (ACS)
Date: 03-04-2012
DOI: 10.1021/JP300471X
Abstract: Anion photoelectron spectra are reported for the iodide-carbon monoxide clusters, with supporting ab initio calculations for the 1:1 dimer anion and neutral complexes. A C(s) minimum geometry is predicted for the anion complex, while for the neutral complex two linear van der Waals minima are predicted differing in the attachment point of the iodine, that is, I···CO and I···OC. The predicted adiabatic photodetachment energy agrees well with the experimental spectrum. The photoelectron spectra feature a vibrational progression in the CO stretching mode, which becomes more pronounced for the larger clusters.
A matrix isolation ESR investigation of the MgCH radical
Publisher: AIP Publishing
Date: 26-09-2019
DOI: 10.1063/1.5119146
Abstract: The MgCH radical and its magnesium-25, carbon-13, and deuterated isotopologs have been isolated in low temperature neon matrices and examined by the matrix isolation electron spin resonance technique for the first time. The radicals were formed through the reactions of laser ablated natural abundance magnesium metal and magnesium-25 enriched magnesium metal with carbon-13 and deuterated isotopologs of acetone. The MgCH radical was shown to have a X4Σ− ground electronic state, and the magnetic parameters determined for this state were g⊥ = 2.001 81(45), g∥ = 2.0018(10), D = 4970(5) MHz, A⊥(13C) = 115(6) MHz, A∥(13C) = 65(15) MHz, A⊥(H) = 34(6) MHz, A∥(H) = 5(10) MHz, A⊥(D) = 5(3) MHz, A⊥(25Mg) = 82(5) MHz, and A∥(25Mg) = 85(10). Comparisons are made between the electronic structure of this radical and the MgCH3 and MgN radicals. Theoretical hyperfine parameters were also evaluated for the MgCH radical, and a potential energy surface for the low-lying electronic states was constructed using complete active space multiconfigurational self-consistent field theory. The leading configuration (96.6%) for the X4Σ− ground electronic state was shown to be 1σ22σ23σ21π44σ25σ26σ27σ12π12π1 with an Mg–C bond length of 2.041 Å for a fixed C–H bond length of 1.090 Å. The Mg–C bond dissociation energy (De) was 48.26 kcal/mol. The optimized geometry from a density functional theory calculation using the B3LYP functional gave a Mg–C bond length of 2.061 Å and a C–H bond length of 1.090 Å.
Spectrum of antibacterial activity and mode of action of a novel tris-stilbene bacteriostatic compound
Publisher: Springer Science and Business Media LLC
Date: 02-05-2018
DOI: 10.1038/S41598-018-25080-W
Abstract: The spectrum of activity and mode of action of a novel antibacterial agent, 135C , was investigated using a range of microbiological and genomic approaches. Compound 135C was active against Gram-positive bacteria with MICs for Staphylococcus aureus ranging from 0.12–0.5 μg/ml. It was largely inactive against Gram-negative bacteria. The compound showed bacteriostatic activity in time-kill studies and did not elicit bacterial cell leakage or cell lysis. Checkerboard assays showed no synergy or antagonism when 135C was combined with a range of other antibacterials. Multi-step serial passage of four S. aureus isolates with increasing concentrations of 135C showed that resistance developed rapidly and was stable after drug-free passages. Minor differences in the fitness of 135C -resistant strains and parent wildtypes were evident by growth curves, but 135C -resistant strains did not show cross-resistance to other antibacterial agents. Genomic comparison of resistant and wildtype parent strains showed changes in genes encoding cell wall teichoic acids. 135C shows promising activity against Gram-positive bacteria but is currently limited by the rapid resistance development. Further studies are required to investigate the effects on cell wall teichoic acids and to determine whether the issue of resistance development can be overcome.
Formation of methanol from methane and water in an electrical discharge
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2CP22135G
Abstract: Matrix isolation FTIR experiments have shown that methanol is a major product when argon gas doped with water and methane is exposed to an electrical discharge and condensed to a solid matrix at 11 K. Experiments with (2)H, (17)O and (18)O-labeled isotopologues show the mechanism for the methanol production is likely to be insertion of an excited oxygen atom in the (1)D state into a C-H bond of a methane molecule. In light of these experiments, the possibility of oxygen atom insertion into methane should be considered as a possible mechanism for the production of methanol in interstellar ices.
Spectroscopic Study of the Br−+CH3I→I−+CH3Br SN2 Reaction
Publisher: Wiley
Date: 11-08-2022
Abstract: Mass spectrometry and anion photoelectron spectroscopy have been used to study the gas‐phase reaction involving and . The anion photoelectron spectra associated with the reaction intermediates of this reaction are presented. High‐level CCSD(T) calculations have been utilised to investigate the reaction intermediates that may form as a result of the reaction along various different reaction pathways, including back‐side attack and front‐side attack. In addition, simulated vertical detachment energies of each reaction intermediate have been calculated to rationalise the photoelectron spectra.
Anion photoelectron spectroscopy and CCSD(T) calculations of the Cl-center dot center dot center dot N-2 complex
Publisher: Elsevier BV
Date: 06-2016
Spectroscopic Investigation of Chalcogen Bonding: Halide–Carbon Disulfide Complexes
Publisher: Wiley
Date: 07-04-2021
Exploring the Catalytic Reactivity of Nickel Phosphine-Phosphite Complexes
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/CH15459
Abstract: In this study, we present an investigation into various nickel phosphite and phosphite–phosphine complexes for use in the Mizoroki–Heck and Suzuki–Miyaura cross-coupling reactions and the ammonia arylation reaction. In these coupling reactions, it was discovered that the Ni[P(OEt)3]4, (dppf)Ni[P(OPh)3]2, and (binap)Ni[P(OPh)3]2 catalysts were the most effective. In addition, an optimisation process for these catalytic systems as well as functional group compatibility are discussed.
Dodecamethylcarba-closo-dodecaboranyl (CB(11)Me(12)(.)), a stable free radical
Publisher: American Chemical Society (ACS)
Date: 1996
DOI: 10.1021/JA9622160
A tale of two conformers: spectroscopic evidence for halide catalysed formic acid isomerisation
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2CP03634G
Abstract: Halide anions are experimentally and theoretically shown to preferentially stabilise the higher energy formic acid conformer. Moreover, halide anions appear to lower the isomerisation barrier associated with conformer interconversion.
Inspiration from Old Dyes: Tris(stilbene) Compounds as Potent Gram‐Positive Antibacterial Agents
Publisher: Wiley
Date: 18-11-2013
Abstract: Herein we describe the preparation and structure-activity relationship studies on range of stilbene based compounds and their antibacterial activity. Two related compounds, each bearing carboxylic acid moieties, exhibit good activity against several bacterial strains, including methicillin-resistant Staphylococcus aureus MRSA (ATCC 33592 and NCTC 10442). Compound 10 was most active against Moraxella catarrhalis with minimum inhibitory concentrations (MICs) of 0.12-0.25 μg mL(-1) and against Staphylococcus spp. with MICs ranging from 2-4 μg mL(-1). The derivative 17 showed increased activity with MICs of 0.06-0.25 μg mL(-1) against M. catarrhalis and 0.12-1 against Staphylococcus spp. This level of activity is similar to that reported for S. aureus for antibiotics, such as vancomycin, with MICs of ≤2.0 μg mL(-1) and clindamycin with MICs of ≤0.5 μg mL(-1). As an indicator of toxicity, 17 was tested for its ability to lyse sheep erythrocytes, and showed low haemolytic activity. Such results highlight the value of tris(stilbene) compounds as antibacterial agents providing suitable properties for further development.
Closing the Shell: Gas‐Phase Solvation of Halides by 1,3‐Butadiene
Publisher: Wiley
Date: 11-05-2023
Abstract: Gas‐phase solvation of halides by 1,3‐butadiene has been studied via a combination of photoelectron spectroscopy and density functional theory. Photoelectron spectra for X − ⋯(C 4 H 6 ) n (X=Cl, Br, I where n =1‐3, 1–3 and 1–7 respectively) are presented. For all complexes, the calculated structures indicate that butadiene is bound in a bidentate fashion through hydrogen‐bonding, with the chloride complex showing the greatest degree of stabilisation of the internal C−C rotation of cis ‐butadiene. In both Cl − and Br − complexes, the first solvation shell is shown to be at least from the vertical detachment energies (VDEs), however for I − , increases in the VDE may suggest a metastable, partially filled, first solvation shell for and a complete shell at . These results have implications for gas‐phase clustering in atmospheric and extraterrestrial environments.
Solar irradiation of the seed germination stimulant karrikinolide produces two novel head-to-head cage dimers
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2OB25090J
Abstract: Karrikinolide is a naturally derived potent seed germination stimulant that is responsible for triggering the germination of numerous plant species from various habitats around the world. We now report that solar irradiation of karrikinolide yields two novel head-to-head cage photodimers with the formation, stability and bioactivity of both presented herein.
LASER VAPORIZATION GENERATION OF (YB+)-B-10, (YB+)-B-11, AND YAL+ FOR ELECTRON-SPIN-RESONANCE STUDIES IN NEON MATRICES AT 4-K - COMPARISON WITH THEORETICAL CALCULATIONS
Publisher: AIP Publishing
Date: 15-03-1993
DOI: 10.1063/1.465000
Abstract: The first spectroscopic investigation of 89Y 10B+, 89Y 11B+, and 89Y 27Al+ is reported, revealing that both of these diatomic cation radicals have X 4Σ− electronic ground states. The ions were generated by three high energy techniques in combination with neon matrix isolation at 4 K and studied by electron spin resonance (ESR) spectroscopy. The generation methods included pulsed laser vaporization of the metal alloys, photoionization at 16.8 eV during matrix deposition, and x-irradiation at 80 keV of the matrix s le following deposition. Hyperfine interactions were resolved for all of the above nuclei and were compared with calculated isotropic and dipolar components of the A tensor. The yttrium 5s character observed in YAl+ was significantly larger than that in YB+ based upon the observed nuclear hyperfine interactions. The calculated electronic structure properties showed agreement with this trend in the observed Aiso parameters. In addition, qualitative descriptions of the bonding properties are also presented which are consistent with the magnetic parameters obtained from the ESR measurements. The magnetic parameters for Y 11B+ in neon at 4 K are g⊥=1.959(1), A⊥ (Y)=33.6(4) MHz, and A⊥(11B)=65.9(4) MHz. For YAl+, g⊥=1.942(1), A⊥=142(1) MHz, and A⊥(Al)=73(1) MHz.
Anion photoelectron spectroscopy and ab initio calculations of the gas phase chloride–carbon monoxide complex: Cl¯··· CO
Publisher: Elsevier BV
Date: 02-2011
LONG-RANGE SPIN-DENSITY PROPAGATION IN SATURATED-HYDROCARBONS - 3-[N]STAFFYL RADICALS
Publisher: American Chemical Society (ACS)
Date: 12-1992
DOI: 10.1021/JA00052A070
Polysilanes - Photochemistry and Deep UV Lithography
Publisher: Wiley
Date: 07-1989
An electron spin resonance investigation of the (CBC)-C-12-B-11-C-12, (CBC)-C-12-B-11-C-13, and (CBC)-C-13-B-11-C-13 radicals in neon, argon, and krypton matrices: Comparison with ab initio calculations
Publisher: AIP Publishing
Date: 04-1996
DOI: 10.1063/1.471125
Abstract: The 11 electron CBC radical has been generated by the pulsed laser vaporization of elemental carbon–boron mixtures and trapped in neon, argon and krypton matrices for detailed electron spin resonance (ESR) studies. Extensive comparisons of the experimental nuclear hyperfine A tenors for carbon and boron were made with a variety of ab initio computational results that involved different levels of theory and basis sets. These new ESR results agree with recent vibrational studies of CBC that show it to have a nonlinear symmetric geometry with a 2A1 electronic ground state. These ESR results provide a description of the singly occupied molecular orbital. The spin density resides primarily on boron in 2s and 2pz orbitals, however a complete resolution of the 13C hyperfine structure does show that approximately 20% resides on the carbon atoms.
A Comparison of Common Swabbing Materials for the Recovery of Organic and Inorganic Explosive Residues
Publisher: Wiley
Date: 04-03-2013
Abstract: The efficiency of solvent based extraction methods used to remove explosive residues from four different swab types was investigated. Known amounts of organic and inorganic residues were spiked onto a swab surface with acetonitrile or ethanol:water combined with ultrasonication or physical manipulation used to extract the residues from each swab. The efficiency of each procedure was then calculated using liquid chromatography-ultraviolet detection for organic residues and ion chromatography for inorganic residues. Results indicated that acetonitrile combined with physical agitation proved to be the most efficient method returning analyte recoveries c. 95% for both alcohol based swabs and cotton balls. Inorganic residues were efficiently extracted using ethanol:water, while the use of acetonitrile followed by water significantly reduced the recovery of inorganic residues. Swab storage conditions were then investigated with results indicating decreased storage temperatures are required to retain the more volatile explosives.
Noncovalent chalcogen and tetrel bonding interactions: Spectroscopic study of halide–carbonyl sulfide complexes
Publisher: Wiley
Date: 06-02-2023
Abstract: Chalcogen and tetrel intermolecular bonding interactions formed between carbonyl sulfide and halide anions have been studied utilizing a combined experimental and theoretical approach. In particular, high‐level CCSD(T) energetics and experimental anion photoelectron spectroscopy have been used in order to assign the dominant binding motif exhibited in these complexes. Halide anions solvated by multiple carbonyl sulfide molecules have also been investigated in order to ascertain the effect that additional binding partners has on the strength of the noncovalent interactions. The experimental and computational results support the main binding motif of carbonyl sulfide molecules with halide anions being chalcogen bonding, both in dimer complexes and larger solvated complexes. In addition, comparison between the noncovalent interactions formed by halides with carbon disulfide, carbonyl sulfide, and carbon dioxide allows a deeper understanding of noncovalent binding strength in relation to isoelectronic species. Spectroscopic and ab initio characterization of halide–carbonyl sulfide van der Waals complexes bound through chalcogen and tetrel bonding. Detailed insight into chalcogen and tetrel bond strength in the context of changing chemical environments. Effect of increasing solvation on noncovalent binding strength.
Effects of Increasing Acidity on Metal(loid) Bioprecipitation in Groundwater: Column Studies
Publisher: American Chemical Society (ACS)
Date: 11-09-2007
DOI: 10.1021/ES071122V
Abstract: Large-scale column experiments were carried out over a period of 545 days to assess the effect of increasing acidity on bacterial denitrification, sulfate reduction, and metal(loid) bioprecipitation in groundwater affected by acid mine drainage. At a groundwater pH of 5.5, denitrification and Cu2+ removal, probably via malachite (Cu2(OH)2CO3) precipitation, were observed in the ethanol-amended column. Sulfate reduction, sulfide production, and Zn2+ removal were also observed, with Zn2+ removal observed in the zone of sulfate reduction, indicating likely precipitation as sphalerite (ZnS). Se6+ removal was also observed in the sulfate reducing zone, probably as direct bioreduction to elemental selenium via ethanol/acetate oxidation or sulfide oxidation precipitating elemental sulfur. A step decrease in groundwater pH from 5.5 to 4.25 resulted in increased denitrification and sulfate reduction half-lives, migration of both these redox zones along the ethanol-amended column, and the formation of an elevated Cu2+ plume. Additionally, an elevated Zn2+ plume formed in the previous sulfate reducing zone of the ethanol-amended column, suggesting dissolution of precipitated sphalerite as a result of the reduction in groundwater pH. As Cu2+ passed through the zone of sphalerite dissolution, SEM imaging and EDS detection suggested that Cu2+ removal had occurred via chalcocite (Cu2S) or covellite (CuS) precipitation.
Electrochemical properties of a verdazyl radical in room temperature ionic liquids
Publisher: CSIRO Publishing
Date: 2020
DOI: 10.1071/CH19575
Matrix-Isolation ESR Studies of the Various Isotopomers of the CH3Zn and ZnH Radicals: Comparisons with ab initio theoretical Calculations
Publisher: American Chemical Society (ACS)
Date: 10-02-2000
DOI: 10.1021/JP993358U
Fate of benzotriazole and 5-methylbenzotriazole in recycled water recharged into an anaerobic aquifer: Column studies
Publisher: Elsevier BV
Date: 03-2015
DOI: 10.1016/J.WATRES.2014.11.040
Abstract: The fate of benzotriazole (BTri) and 5-methylbenzotriazole (5-MeBT) was investigated under anaerobic conditions at nano gram per litre concentrations in large-scale laboratory columns to mimic a managed aquifer recharge replenishment strategy in Western Australia. Investigations of BTri and 5-MeBT sorption behaviour demonstrated mobility of the compounds with retardation coefficients of 2.0 and 2.2, respectively. Degradation processes over a period of 220 days indicated first order biodegradation of the BTri and 5-MeBT under anaerobic aquifer conditions after a biological lag-time of approximately 30-60 days. Biodegradation half-lives of 29 ± 2 and 26 ± 1 days for BTri and 5-MeBT were respectively observed, with no threshold effect to biodegradation observed at the 200 ng L(-1). The detection of degradation products provided further evidence of BTri and 5-MeBT biodegradation. These results suggested that if BTri and 5-MeBT were present in recycled water recharged to the Leederville aquifer, biodegradation during aquifer passage is likely given sufficient aquifer residence times or travel distances between recycled water injection and groundwater extraction.
Iron in soil kaolins from Indonesia and Western Australia
Publisher: Mineralogical Society
Date: 12-2002
Abstract: Soil kaolins from Indonesia and Western Australia and a range of reference kaolins were studied using Mössbauer spectroscopy, electron paramagnetic resonance (EPR) spectroscopy and SQUID magnetometry. Mössbauer spectra indicate that the Fe within the kaolins is in the highspin Fe 3+ oxidation state and that a large fraction of the Fe is present as dispersed atoms residing within the octahedral sites of the kaolinite crystal structure. The EPR spectra are typical for soil kaolins except for the absence of radiation-induced defects for the Indonesian kaolins. The Fe (I) spectra are dominant with a strong symmetric peak at g = 4.3, the presence of Fe(II) spectra is shown by a shoulder on this peak at g = 4.9 and a small phase up peak at g = 9.2. Low-temperature (5 K) magnetization ( M ) measurements over large field ( H ) sweeps (±70 kOe) yielded M ( H ) curves which are fitted well with Brillouin functions indicating the paramagnetic nature of the kaolins at temperatures down to 5 K. A very small remanent magnetization was detectable in the kaolins. Remanent magnetization to saturation magnetization ratios ranged from 10 –4 to 10 –3 for the Indonesian kaolins and were all ∼10 –3 for the Western Australian kaolins, indicating that at high fields the vast majority of the magnetization of the kaolins is due to paramagnetic ions. Zero-field-cooled and field-cooled magnetization measurements in small fields (500 Oe) indicate that the Indonesian kaolins are generally free from magnetically-blocked material down to a temperature of 5 K. The magnetic susceptibility of the Indonesian kaolins shows Curie Law behaviour indicating paramagnetic behaviour over all temperatures down to 5 K. Measurements on the Western Australian kaolins indicated the presence of some magnetic material that is magnetically blocked at temperatures below ∼200 250 K. As a consequence, the magnetic susceptibility showed large deviations from Curie Law behaviour.
Solution Photochemistry of Poly(di-n-alkylsilane)s. An EPR-ENDOR Study of the Structure of the Persistent Radicals
Publisher: American Chemical Society (ACS)
Date: 03-1991
DOI: 10.1021/JA00006A022
Tailoring the photocatalytic activity of nanoparticulate zinc oxide by transition metal oxide doping
Publisher: Elsevier BV
Date: 03-2009
Asymmetric halogen dioxides
Publisher: Elsevier BV
Date: 07-2020
The Bromide-Carbon monoxide gas phase complex: Anion photoelectron spectroscopy and Ab initio calculations
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/CH12007
Abstract: The anion photoelectron spectrum of the bromide–carbon monoxide complex is presented in combination with supporting ab initio calculations. The spectrum features transitions between anion and neutral van der Waals complexes, Br⋯CO. A stabilization energy of 0.14 ± 0.05 eV is extracted from the spectrum, while the predicted binding energy for the anion complex is 9.9 kJ mol–1 from CCSD(T)/aug-cc-pVTZ calculations. The electron affinity of the Br⋯CO complex is 3.50 ± 0.05 eV. The ab initio calculations reveal a previously unreported minimum for the neutral radical complex, namely the van der Waals Br⋯OC linear complex.
Electronic structure of PH2− containing complexes as photoelectron spectroscopy candidates
Publisher: Elsevier BV
Date: 04-2023
A matrix isolation ESR investigation of Mg+-N2
Publisher: AIP Publishing
Date: 14-05-2019
DOI: 10.1063/1.5090923
Abstract: The adducts formed between 25Mg+ with 14N2 and 25Mg+ with 15N2 have been trapped in a solid neon matrix and studied with electron spin resonance (ESR) spectroscopy. These radical species were formed through the interaction of laser ablated magnesium and nitrogen gas. The Mg+-N2 radical species was found to have a ground electronic state of 2Σ+ in a linear configuration with discrete coupling to the proximate nitrogen resolved in the spectra. Fitting the ESR spectra allowed magnetic parameters to be determined as follows: g⊥ = 2.0012(5), g∥ = 2.0015(8), A⊥(1-14N) = 32(3) MHz, A∥(1-14N) = 34(5) MHz, A⊥(1-15N) = 45(4) MHz, A∥(1-15N) = 47(6) MHz, A⊥(25Mg) = −581(5) MHz, and A∥(25Mg) = −582(5) MHz, and estimates derived for A⊥(2-14N) = 1(2) MHz, A∥(2-14N) = 2(5) MHz, A⊥(2-15N) = 2(2) MHz, and A∥(2-15N) = 4(6) MHz. Ab initio calculations using the coupled-cluster single double triple methodology showed that the linear form was 59.7 kcal mol−1 more stable than the T-shaped form. The potential energy curve around the equilibrium geometry was explored using the complete active space self-consistent field approach, and Hartree–Fock singles and double configuration interaction and multireference singles and double configuration interaction calculations of the hyperfine coupling constants were undertaken, and reasonable agreement with the experiment was observed.
Matrix isolation ESR and theoretical studies of metal phosphides
Publisher: AIP Publishing
Date: 26-10-2010
DOI: 10.1063/1.3491501
Abstract: The ZnP, Z67nP, CdP, C111dP, and C113dP radicals have been formed by laser ablation of the metal with GaP pressed into the metal surface, isolated in an inert neon matrix at 4.3 K and their electronic structure was established using electron spin resonance spectroscopy. The following magnetic parameters were determined experimentally for ZnP/Z67nP, g⊥=1.9982(2), A⊥(P)=111(6) MHz, A⊥(Z67n)=160(2) MHz, and D=−29 988(3) MHz and estimates were made for the following ZnP/Z67nP magnetic parameters: g∥=1.9941(2), A∥(P)=−5(6) MHz, and A∥(Z67n)=180(50) MHz. The following magnetic parameters for CdP/C111dP/C113dP were determined experimentally: g⊥=1.9963(2), A⊥(P)=97(3) MHz, A⊥(C111d)=862(3) MHz, and A⊥(C113d)=902(3) MHz. Evidence for the formation of the MgP radical was also obtained and an approximate hyperfine coupling constant of A⊥(P)=157(6) MHz was determined. The low-lying electronic states of ZnP and MgP were also investigated using the multiconfigurational self-consistent field technique. Potential energy surfaces, binding energies, optimized bond lengths, energy separations, and dissociation energies have been determined. Both radicals are found to have Σ4− ground states with a leading configuration at re of 10σ211σ25π15π112σ1 for ZnP and 7σ28σ23π13π19σ1 for MgP. Significant mixing to this state is calculated for MgP.
Longitudinal heterogeneity effects in alkaline surfactant polymer flooding enhanced oil recovery
Publisher: SPE
Date: 31-03-2014
DOI: 10.2118/169675-MS
Abstract: This paper describes experimental work to study the impact of longitudinal heterogeneity of porous medium (in terms of permeability) on the efficiency of ASP flooding that has been practiced in Enhance Oil Recovery (EOR). EOR becomes increasingly important as the globally proved crude oil reserves are being depleted. Chemical flooding is one of the tools to increase recovery however, is still an active area for integrated research as it involves geochemistry, pore structure, microemulsion, fluid flow and chemical transport in porous media. This present study is based on the use of carefully designed heterogeneous sand packs and monitors the effect of heterogeneity on the enhanced oil recovery by ASP slug. Oil recovery measurements were made based on mass measurements. Results include the chemical profiles and its relation to EOR. The results indicate that longitudinal heterogeneities can impact EOR and the flooding of ASP slug from lower-to-higher permeability transition can mitigate the heterogeneity influence on EOR. In this experimental investigation, an enhancement of 5% (Original Oil in Place) was found when the ASP flood goes from lower-to-higher permeability transition as compared to that from higher-to-lower permeability transition. This finding can be of great importance to operators interested in implementing ASP floods.
Fate of N-Nitrosodimethylamine in recycled water after recharge into anaerobic aquifer
Publisher: Elsevier BV
Date: 03-2012
DOI: 10.1016/J.WATRES.2011.12.032
Abstract: Laboratory and field experiments were undertaken to assess the fate of N-nitrosodimethylamine (NDMA) in aerobic recycled water that was recharged into a deep anaerobic pyritic aquifer, as part of a managed aquifer recharge (MAR) strategy. Laboratory studies demonstrated a high mobility of NDMA in the Leederville aquifer system with a retardation coefficient of 1.1. Anaerobic degradation column and (14)C-NDMA microcosm studies showed that anaerobic conditions of the aquifer provided a suitable environment for the biodegradation of NDMA with first-order kinetics. At microgram per litre concentrations, inhibition of biodegradation was observed with degradation half-lives (260±20 days) up to an order of magnitude greater than at nanogram per litre concentrations (25-150 days), which are more typical of environmental concentrations. No threshold effects were observed at the lower ng L(-1) concentrations with NDMA concentrations reduced from 560 ng L(-1) to <6 ng L(-1) over a 42 day 14C-NDMA aerobic microcosm experiment. Aerobic (14)C-NDMA microcosm studies were also undertaken to assess potential aerobic degradation, likely to occur close to the recharge bore. These microcosm experiments showed a faster degradation rate than anaerobic microcosms, with a degradation half-life of 8±2 days, after a lag period of approximately 10 days. Results from a MAR field trial recharging the Leederville aquifer with aerobic recycled water showed that NDMA concentrations reduced from 2.5±1.0 ng L(-1) to 1.3±0.4 ng L(-1) between the recharge bore and a monitoring location 20 m down gradient (an estimated aquifer residence time of 10 days), consistent with data from the aerobic microcosm experiment. Further down gradient, in the anaerobic zone of the aquifer, NDMA degradation could not be assessed, as NDMA concentrations were too close to their analytical detection limit (<1 ng L(-1)).
Infrared Measurements and Calculations on H2O·HO
Publisher: American Chemical Society (ACS)
Date: 26-04-2003
DOI: 10.1021/JA034388K
Abstract: We have measured the infrared spectrum of H2O.HO in argon matrices at 11.5 +/- 0.5 K. We have also calculated the vibrational frequencies and intensities of the H2O.HO complex. As a result of these measurements and calculations, we have assigned a previously unassigned absorption band at 3442.1 cm-1 to the OH stretch in the radical complexed to the water molecule. This absorption originates from a complex that is situated in a different site within the argon matrix to those absorptions already assigned to this vibration at 3452.2 and 3428.0 cm-1. We observe a decrease in intensity of the OH radical stretching vibration of the H2O.HO complex upon isotopic substitution of D for H that agrees well with our calculations.
Photodegradation of Poly(dialkylsilane)s In Solution
Publisher: American Chemical Society (ACS)
Date: 12-1988
DOI: 10.1021/OM00102A025
Hydrogen Bonding versus Halogen Bonding: Spectroscopic Investigation of Gas‐Phase Complexes Involving Bromide and Chloromethanes
Publisher: Wiley
Date: 03-01-2023
Abstract: Hydrogen bonding and halogen bonding are important non‐covalent interactions that are known to occur in large molecular systems, such as in proteins and crystal structures. Although these interactions are important on a large scale, studying hydrogen and halogen bonding in small, gas‐phase chemical species allows for the binding strengths to be determined and compared at a fundamental level. In this study, anion photoelectron spectra are presented for the gas‐phase complexes involving bromide and the four chloromethanes, CH 3 Cl, CH 2 Cl 2 , CHCl 3 , and CCl 4 . The stabilisation energy and electron binding energy associated with each complex are determined experimentally, and the spectra are rationalised by high‐level CCSD(T) calculations to determine the non‐covalent interactions binding the complexes. These calculations involve nucleophilic bromide and electrophilic bromine interactions with chloromethanes, where the binding motifs, dissociation energies and vertical detachment energies are compared in terms of hydrogen bonding and halogen bonding.
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