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Ali Redha A, Torquati L, Langston F, Nash GR, Gidley MJ, Cozzolino D. Determination of glucosinolates and isothiocyanates in glucosinolate-rich vegetables and oilseeds using infrared spectroscopy: A systematic review. Crit Rev Food Sci Nutr 2023:1-17. [PMID: 37035931 DOI: 10.1080/10408398.2023.2198015] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
Abstract
Cruciferous vegetables and oilseeds are rich in glucosinolates that can transform into isothiocyanates upon enzymic hydrolysis during post-harvest handling, food preparation and/or digestion. Vegetables contain glucosinolates that have beneficial bioactivities, while glucosinolates in oilseeds might have anti-nutritional properties. It is therefore important to monitor and assess glucosinolates and isothiocyanates content through the food value chain as well as for optimized crop production. Vibrational spectroscopy methods, such as infrared (IR) spectroscopy, are used as a nondestructive, rapid and low-cost alternative to the current and common costly, destructive, and time-consuming techniques. This systematic review discusses and evaluates the recent literature available on the use of IR spectroscopy to determine glucosinolates and isothiocyanates in vegetables and oilseeds. NIR spectroscopy was used to predict glucosinolates in broccoli, kale, rocket, cabbage, Brussels sprouts, brown mustard, rapeseed, pennycress, and a combination of Brassicaceae family seeds. Only one study reported the use of NIR spectroscopy to predict broccoli isothiocyanates. The major limitations of these studies were the absence of the critical evaluation of errors associated with the reference method used to develop the calibration models and the lack of interpretation of loadings or regression coefficients used to predict glucosinolates.
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Affiliation(s)
- Ali Ali Redha
- The Department of Public Health and Sport Sciences, University of Exeter Medical School, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
- Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation (QAAFI), The University of Queensland, Brisbane, QLD, Australia
| | - Luciana Torquati
- The Department of Public Health and Sport Sciences, University of Exeter Medical School, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Faye Langston
- Natural Sciences, Faculty of Environment, Science and Economy, University of Exeter, Exeter, UK
| | - Geoffrey R Nash
- Natural Sciences, Faculty of Environment, Science and Economy, University of Exeter, Exeter, UK
| | - Michael J Gidley
- Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation (QAAFI), The University of Queensland, Brisbane, QLD, Australia
| | - Daniel Cozzolino
- Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation (QAAFI), The University of Queensland, Brisbane, QLD, Australia
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Menghrajani KS, Nash GR, Barnes WL. Vibrational Strong Coupling with Surface Plasmons and the Presence of Surface Plasmon Stop Bands. ACS Photonics 2019; 6:2110-2116. [PMID: 31475218 PMCID: PMC6711361 DOI: 10.1021/acsphotonics.9b00662] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Indexed: 05/10/2023]
Abstract
We demonstrate strong coupling between surface plasmon resonances and molecular vibrational resonances of poly(methyl methacrylate) (PMMA) molecules in the mid-infrared range through the use of grating coupling, complimenting earlier work using microcavities and localized plasmon resonances. We choose the period of the grating so that we may observe strong coupling between the surface plasmon mode associated with a patterned gold film and the C=O vibrational resonance in an overlying polymer film. We present results from experiments and numerical simulations to show that surface plasmon modes provide convenient open cavities for vibrational strong coupling experiments. In addition to providing momentum matching between surface plasmon modes and incident light, gratings may also produce a modification of the surface plasmon properties, notably their dispersion. We further show that for the parameters used in our experiment surface plasmon stop bands are formed, and we find that both stop-band edges undergo strong coupling.
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Affiliation(s)
- Kishan S. Menghrajani
- College of Engineering, Mathematics
and Physical Sciences, University of Exeter, Exeter, EX4 4QF, U.K.
| | - Geoffrey R. Nash
- College of Engineering, Mathematics
and Physical Sciences, University of Exeter, Exeter, EX4 4QF, U.K.
| | - William L. Barnes
- College of Engineering, Mathematics
and Physical Sciences, University of Exeter, Exeter, EX4 4QF, U.K.
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Abstract
Surface acoustic waves (SAWs) are elastic waves that can be excited directly on the surface of piezoelectric crystals using a transducer, leading to their exploitation for numerous technological applications, including for example microfluidics. Recently, the concept of SAW streaming, which underpins SAW microfluidics, was extended to make the first experimental demonstration of ‘SAW swimming’, where instead of moving water droplets on the surface of a device, SAWs are used as a propulsion mechanism. Using theoretical analysis and experiments, we show that the SAW swimming force can be controlled directly by changing the SAW frequency, due to attenuation and changing force distributions within each SAW streaming jet. Additionally, an optimum frequency exists which generates a maximum SAW swimming force. The SAW frequency can therefore be used to control the efficiency and forward force of these SAW swimming devices. The SAW swimming propulsion mechanism also mimics that used by many microorganisms, where propulsion is produced by a cyclic distortion of the body shape. This improved understanding of SAW swimming provides a test-bed for exploring the science of microorganism swimming, and could bring new insight to the evolutionary significance for the length and beating frequency of swimming microbial flagella.
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Affiliation(s)
- C Pouya
- 1 College of Engineering, Mathematics and Physical Sciences, University of Exeter , Exeter EX4 4QF , UK
| | - K Hoggard
- 1 College of Engineering, Mathematics and Physical Sciences, University of Exeter , Exeter EX4 4QF , UK
| | - S H Gossage
- 2 Natural Sciences, University of Exeter , Exeter, EX4 4QF , UK
| | - H R Peter
- 2 Natural Sciences, University of Exeter , Exeter, EX4 4QF , UK
| | - T Poole
- 1 College of Engineering, Mathematics and Physical Sciences, University of Exeter , Exeter EX4 4QF , UK
| | - G R Nash
- 1 College of Engineering, Mathematics and Physical Sciences, University of Exeter , Exeter EX4 4QF , UK.,2 Natural Sciences, University of Exeter , Exeter, EX4 4QF , UK
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Shi C, Luxmoore IJ, Nash GR. Gate tunable graphene-integrated metasurface modulator for mid-infrared beam steering. Opt Express 2019; 27:14577-14584. [PMID: 31163903 DOI: 10.1364/oe.27.014577] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 04/30/2019] [Indexed: 06/09/2023]
Abstract
The ability to integrate graphene into metasurface devices has attracted enormous interest as a means of achieving dynamic electrical control of their electromagnetic response. In this manuscript, we experimentally demonstrate a graphene-integrated metasurface modulator that establishes the potential to actively control the amplitude and phase of mid-infrared light with high modulation depth and speed, in good agreement with simulation results. Our simulations also show it is possible to construct a reconfigurable surface with tunable phase profile by incorporating graphene-integrated metasurface modulators with specific geometric parameters. This reconfigurable surface is able to manipulate the orientation of the wave reflected from it, achieving a high-speed, switchable beam steering reflective interface. The results here could inspire research on dynamic reflective display and holograms.
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Owens CL, Nash GR, Hadler K, Fitzpatrick RS, Anderson CG, Wall F. Apatite enrichment by rare earth elements: A review of the effects of surface properties. Adv Colloid Interface Sci 2019; 265:14-28. [PMID: 30711795 DOI: 10.1016/j.cis.2019.01.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 01/18/2019] [Accepted: 01/21/2019] [Indexed: 10/27/2022]
Abstract
Apatite subspecies depend on their halogen and hydroxyl content; chlorapatite, hydroxylapatite and fluorapatite, with additional substitution of other elements within the lattice such as rare earth elements (REE), sodium, strontium and manganese also possible. Rare earth elements are vital to green and emerging technologies, with demand set to outstrip supply. Apatite provides a possible future source of REE. Processing rare earth deposits is often complex, with surface behaviour having a significant effect on the optimization of a process flow sheet. The effect of enrichment of natural apatite and the doping of synthetic apatite on surface behaviour can be determined by measuring the zeta potential and the isoelectric point of the mineral. In this paper, we review zeta potential studies of natural and synthetic apatite to determine the effect of elemental enrichment on surface behaviour. Fifty three studies of natural apatite and forty four studies of synthetic apatite were reviewed. The isoelectric point of apatite varied from pH 1 to pH 8.7, with studies of apatite specified to be >90% pure reducing the variation to pH 3 to pH 6.5. Of the four studies of rare earth enriched apatite found, three had IEP values between pH 3 and pH 4. A study of synthetic apatite showing enrichment of between 1 and 10% by the REE europium does not affect surface behaviour. However, no studies were found that investigated the effect of common REE processing reagents on REE enriched apatite zeta potentials. Therefore, in addition to comparing previous studies we also therefore present new zeta potential measurements of apatite from a REE enriched deposit under water and common flotation collector conditions. The IEP value of this apatite under water conditions was at pH 3.6, shifting to <3.5 under both hydroxamic acid and betacol conditions. When compared to previous studies, the behaviour of REE enriched apatite under collector conditions is similar to non-REE apatite. This result could be important for future processing of apatite enriched with REE, and therefore global apatite and rare earth supply.
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Shi C, Penrose C, Pitts JE, Gowda P, Luxmoore IJ, Nash GR. Metamaterial-enhanced infrared attenuated total reflection spectroscopy. Nanoscale Adv 2019; 1:476-480. [PMID: 36132247 PMCID: PMC9473245 DOI: 10.1039/c8na00279g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 10/11/2018] [Indexed: 06/15/2023]
Abstract
The use of Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR) allows solid or liquid samples to be characterised directly without specific sample preparation. In such a system, the evanescent waves generated through total internal reflection within a crystal interact with the sample under test. In this work we explore the use of a mid-infrared metasurface to enhance the interaction between molecular vibrations and the evanescent waves. A complementary ring-resonator structure was patterned onto both silicon and SiO2/Si substrates, and the spectral properties of both devices were characterised using a FTIR-ATR system. Minima in reflectance were observed corresponding to the resonance of the metasurface on the silicon substrate, and to the hybrid resonance of phonon modes and metasurface resonances on the SiO2/Si substrate, in good agreement with simulations. Preliminary experiments were undertaken using mixtures containing trace amounts of butyl acetate diluted with oleic acid. Without the use of a metasurface, the minimum concentration of butyl acetate that could be clearly detected was 10%, whereas the use of the metasurface on the SiO2/Si substrate allowed the detection of 1% butyl acetate. This demonstrates the potential of using metasurfaces to enhance trace chemical detection in FTIR-ATR systems.
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Affiliation(s)
- Cheng Shi
- College of Engineering, Mathematics and Physical Sciences, University of Exeter Exeter EX4 4QF UK
| | - Callum Penrose
- College of Engineering, Mathematics and Physical Sciences, University of Exeter Exeter EX4 4QF UK
| | - Jaqueline E Pitts
- College of Engineering, Mathematics and Physical Sciences, University of Exeter Exeter EX4 4QF UK
| | - Prarthana Gowda
- College of Engineering, Mathematics and Physical Sciences, University of Exeter Exeter EX4 4QF UK
| | - Isaac J Luxmoore
- College of Engineering, Mathematics and Physical Sciences, University of Exeter Exeter EX4 4QF UK
| | - Geoffrey R Nash
- College of Engineering, Mathematics and Physical Sciences, University of Exeter Exeter EX4 4QF UK
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Owens CL, Schach E, Rudolph M, Nash GR. Correction: Surface nanobubbles on the carbonate mineral dolomite. RSC Adv 2019; 9:21206. [PMID: 35532492 PMCID: PMC9066166 DOI: 10.1039/c9ra90050k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 06/21/2019] [Indexed: 12/02/2022] Open
Abstract
Correction for ‘Surface nanobubbles on the carbonate mineral dolomite’ by Camilla L. Owens et al., RSC Adv., 2018, 8, 35448–35452.
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Affiliation(s)
- Camilla L. Owens
- College of Engineering, Mathematics and Physical Sciences
- University of Exeter
- UK
| | - Edgar Schach
- Helmholtz Institute Freiberg for Resource Technology
- Helmholtz-Zentrum Dresden-Rossendorf
- 09599 Freiberg
- Germany
| | - Martin Rudolph
- Helmholtz Institute Freiberg for Resource Technology
- Helmholtz-Zentrum Dresden-Rossendorf
- 09599 Freiberg
- Germany
| | - Geoffrey R. Nash
- College of Engineering, Mathematics and Physical Sciences
- University of Exeter
- UK
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Owens CL, Nash GR, Hadler K, Fitzpatrick RS, Anderson CG, Wall F. Zeta potentials of the rare earth element fluorcarbonate minerals focusing on bastnäsite and parisite. Adv Colloid Interface Sci 2018; 256:152-162. [PMID: 29724405 DOI: 10.1016/j.cis.2018.04.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 03/27/2018] [Accepted: 04/14/2018] [Indexed: 11/19/2022]
Abstract
Rare earth elements (REE) are critical to a wide range of technologies ranging from mobile phones to wind turbines. Processing and extraction of REE minerals from ore bodies is, however, both challenging and relatively poorly understood, as the majority of deposits contain only limited enrichment of REEs. An improved understanding of the surface properties of the minerals is important in informing and optimising their processing, in particular for separation by froth flotation. The measurement of zeta potential can be used to extract information regarding the electrical double layer, and hence surface properties of these minerals. There are over 34 REE fluorcarbonate minerals currently identified, however bastnäsite, synchysite and parisite are of most economic importance. Bastnäsite-(Ce), the most common REE fluorcarbonate, supplies over 50% of the world's REE. Previous studies of bastnäsite have showed a wide range of surface behaviour, with the iso-electric point (IEP), being measured between pH values of 4.6 and 9.3. In contrast, no values of IEP have been reported for parisite or synchysite. In this work, we review previous studies of the zeta potentials of bastnäsite to investigate the effects of different methodologies and sample preparation. In addition, measurements of zeta potentials of parisite under water, collector and supernatant conditions were conducted, the first to be reported. These results showed an iso-electric point for parisite of 5.6 under water, with a shift to a more negative zeta potential with both collector (hydroxamic and fatty acids) and supernatant conditions. The IEP with collectors and supernatant was <3.5. As zeta potential measurements in the presence of reagents and supernatants are the most rigorous way of determining the efficiency of a flotation reagent, the agreement between parisite zeta potentials obtained here and previous work on bastnäsite suggests that parisite may be processed using similar reagent schemes to bastnäsite. This is important for future processing of REE deposits, comprising of more complex REE mineralogy.
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Affiliation(s)
- C L Owens
- College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF, United Kingdom; Camborne School of Mines, University of Exeter, Penryn TR10 9FE, United Kingdom.
| | - G R Nash
- College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF, United Kingdom
| | - K Hadler
- Department of Earth Science and Engineering, Imperial College London, SW7 2AZ London, United Kingdom
| | - R S Fitzpatrick
- Camborne School of Mines, University of Exeter, Penryn TR10 9FE, United Kingdom
| | - C G Anderson
- Kroll Institute for Extractive Metallurgy, George S. Ansell Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO 80401, United States
| | - F Wall
- Camborne School of Mines, University of Exeter, Penryn TR10 9FE, United Kingdom
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Owens C, Schach E, Rudolph M, Nash GR. Surface nanobubbles on the carbonate mineral dolomite. RSC Adv 2018; 8:35448-35452. [PMID: 35547923 PMCID: PMC9087822 DOI: 10.1039/c8ra07952h] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 07/08/2019] [Accepted: 10/10/2018] [Indexed: 01/15/2023] Open
Abstract
Analysis of surface nanobubbles on dolomite show that their pinning is affected by the surfactants using in mineral processing.
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Affiliation(s)
- Camilla L. Owens
- College of Engineering, Mathematics and Physical Sciences
- University of Exeter
- UK
| | - Edgar Schach
- Helmholtz Institute Freiberg for Resource Technology
- Helmholtz-Zentrum Dresden-Rossendorf
- Germany
| | - Martin Rudolph
- Helmholtz Institute Freiberg for Resource Technology
- Helmholtz-Zentrum Dresden-Rossendorf
- Germany
| | - Geoffrey R. Nash
- College of Engineering, Mathematics and Physical Sciences
- University of Exeter
- UK
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Carrillo SGC, Nash GR, Hayat H, Cryan MJ, Klemm M, Bhaskaran H, Wright CD. Design of practicable phase-change metadevices for near-infrared absorber and modulator applications. Opt Express 2016; 24:13563-73. [PMID: 27410372 DOI: 10.1364/oe.24.013563] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Phase-change chalcogenide alloys, such as Ge2Sb2Te5 (GST), have very different optical properties in their amorphous and crystalline phases. The fact that such alloys can be switched, optically or electrically, between such phases rapidly and repeatedly means that they have much potential for applications as tunable photonic devices. Here we incorporate chalcogenide phase-change films into a metal-dielectric-metal metamaterial electromagnetic absorber structure and design absorbers and modulators for operation at technologically important near-infrared wavelengths, specifically 1550 nm. Our design not only exhibits excellent performance (e.g. a modulation depth of ~77% and an extinction ratio of ~20 dB) but also includes a suitable means for protecting the GST layer from environmental oxidation and is well-suited, as confirmed by electro-thermal and phase-transformation simulations, to in situ electrical switching. We also present a systematic study of design optimization, including the effects of expected manufacturing tolerances on device performance and, by means of a sensitivity analysis, identify the most critical design parameters.
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Gan CH, Nash GR. Broadband and efficient plasmonic control in the near-infrared and visible via strong interference of surface plasmon polaritons. Opt Lett 2013; 38:4453-4456. [PMID: 24177117 DOI: 10.1364/ol.38.004453] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Broadband and tunable control of surface plasmon polaritons in the near-infrared and visible spectrum is demonstrated theoretically and numerically with a pair of phased nanoslits. We establish, with simulations supported by a coupled wave model, that by dividing the incident power equally between two input channels, the maximum plasmon intensity deliverable to either side of the nanoslit pair is twice that for an isolated slit. For a broadband source, a compact device with nanoslit separation of the order of a tenth of the wavelength is shown to steer nearly all the generated plasmons to one side for the same phase delay, thereby achieving a broadband unidirectional plasmon launcher. The reported effect can be applied to the design of ultra-broadband and efficient tunable plasmonic devices.
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Nash GR, Bending SJ, Boero M, Grambow P, Eberl K, Kershaw Y. Anisotropic surface acoustic wave scattering in quantum-wire arrays. Phys Rev B Condens Matter 1996; 54:R8337-R8340. [PMID: 9984589 DOI: 10.1103/physrevb.54.r8337] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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