ORCID Profile
0000-0001-7973-336X
Current Organisations
Urmia University
,
Queensland University of Technology
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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)
Atomic, Molecular, Nuclear, Particle and Plasma Physics | Nanotechnology | Optical Physics | Chemical Spectroscopy | Lasers and Quantum Electronics | Optics And Opto-Electronic Physics | Plasma Physics; Fusion Plasmas; Electrical Discharges | Atomic and Molecular Physics
ANZSRC Socio-Economic Objective (SEO)
Law enforcement | Expanding Knowledge in the Chemical Sciences | Expanding Knowledge in the Physical Sciences | Physical sciences | Expanding Knowledge in Technology |
Related Links
Publications
International comparisons of He-Ne lasers stabilized with 127I2 at λ≈633 nm (July 1993 to September 1995). Part V: Comparison of Asian-Pacific and South African lasers at λ≈633 nm
Publisher: IOP Publishing
Date: 04-2000
Are plasmons responsible for the Raman signal enhancement observed with gold nanoparticle sensors?
Publisher: IEEE
Date: 08-2011
Effects of Vermicompost, Compost and Animal Manure on Vegetative Growth, Physiological and Antioxidant Activity Characteristics of Thymus vulgaris L. under Water Stress
Publisher: Yuzuncu Yil Universitesi Tarim Bilimleri Dergisi
Date: 31-03-2023
Abstract: This study investigated the effect of organic fertilizers on vegetative growth and the physiological and antioxidant activity characteristics of thyme plants grown under stress. A factorial experiment was conducted according to randomized complete block design with 12 combinations and 3 replications in the 2018 growing season. The experiment factors were the implementation of organic fertilizers at 4 levels (vermicompost, manure compost, animal manure, and control) and irrigation regime at 3 levels (Irr1, Irr2, and Irr3, respectively, irrigation after 60, 90, and 120 mm evaporation from A pan). The results showed that With delayed irrigation, the chlorophyll a and b contents, total chlorophyll, and carotenoid decreased, while the application of low water stress enhanced the amount of oil and the oil yield with the respective highest values of 2.61% and 3.68 g/m under mild stress conditions. Nonetheless, higher values for the aforementioned properties were noted with the application of vermicompost. Water deficit decreased nutrient uptake (K, P, and N) and relative water content, biological yield, and seed yield of thyme, indicating that thyme was sensitive to drought, and organic fertilizers application improved nutrient uptake (K, P, and N) and relative water content, biological yield and seed yield of the plant within irrigation levels. The activities of catalase, superoxide dismutase and ascorbate peroxidase were reduced under organic fertilizers such as vermicompost and manure compost as compared with control under drought stress. The plants of thyme showed a good response to organic fertilizers under water deficit circumstances, with vermicompost being the most effective.
Statistical Disclosure Control For Continuous Variables Using An Extended Skew-T Copula
Publisher: Wiley
Date: 06-10-2022
DOI: 10.1002/ASMB.2650
Abstract: In this article, we extend the skew‐t data perturbation (STDP) to develop a new statistical disclosure control (SDC) method for data with continuous variables. In this new SDC method, we construct an extended skew‐t (EST) copula to release confidential data for third‐party usage. Using the EST copula for producing perturbed data, we can incorporate rich statistical information in the perturbed data while preserving the marginal distributions of the data. An advancement of this EST‐SDC method is to use a copula distribution, which allows generation of perturbed data from bivariate conditional EST copulas sequentially. We discuss the methodology of EST‐SDC and outline some statistical properties derived from copula theories. Simulations and a real data study are included to demonstrate how the EST‐SDC method can be applied and to compare with the STDP method.
Intracavity iodine cell spectroscopy with an extended-cavity laser diode around 633 nm
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-1997
DOI: 10.1109/19.571798
Residual amplitude modulation mechanisms in modulation transfer spectroscopy that use electro-optic modulators
Publisher: IOP Publishing
Date: 30-12-2009
Komplementäre Therapien in den Leitlinien für die Behandlung des Fibromyalgiesyndroms Update 2012
Publisher: S. Karger AG
Date: 2012
DOI: 10.1159/000346147
A method to remotely measure temperature change in a lithium niobate crystal using birefringence
Publisher: European Optical Society
Date: 20-03-2009
Diversity of inhibitory and excitatory parvalbumin interneuron circuits in the dorsal horn
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 28-07-2021
DOI: 10.1097/J.PAIN.0000000000002422
Abstract: Parvalbumin-expressing interneurons (PVINs) in the spinal dorsal horn are found primarily in laminae II inner and III. Inhibitory PVINs play an important role in segregating innocuous tactile input from pain-processing circuits through presynaptic inhibition of myelinated low-threshold mechanoreceptors and postsynaptic inhibition of distinct spinal circuits. By comparison, relatively little is known of the role of excitatory PVINs (ePVINs) in sensory processing. Here, we use neuroanatomical and optogenetic approaches to show that ePVINs comprise a larger proportion of the PVIN population than previously reported and that both ePVIN and inhibitory PVIN populations form synaptic connections among (and between) themselves. We find that these cells contribute to neuronal networks that influence activity within several functionally distinct circuits and that aberrant activity of ePVINs under pathological conditions is well placed to contribute to the development of mechanical hypersensitivity.
Real-time detection of concealed chemical hazards under ambient light conditions using raman spectroscopy
Publisher: Wiley
Date: 21-05-2013
Abstract: Current concerns regarding terrorism and international crime highlight the need for new techniques for detecting unknown and hazardous substances. A novel Raman spectroscopy-based technique, spatially offset Raman spectroscopy (SORS), was recently devised for noninvasively probing the contents of diffusely scattering and opaque containers. Here, we demonstrate a modified portable SORS sensor for detecting concealed substances in-field under different background lighting conditions. S les including explosive precursors, drugs, and an organophosphate insecticide (chemical warfare agent surrogate) were concealed inside diffusely scattering packaging including plastic, paper, and cloth. Measurements were carried out under incandescent and fluorescent light as well as under daylight to assess the suitability of the probe for different real-life conditions. In each case, it was possible to identify the substances against their reference Raman spectra in less than 1 min. The developed sensor has potential for rapid detection of concealed hazardous substances in airports, mail distribution centers, and customs checkpoints.
Reducing residual amplitude modulation in electro-optic phase modulators by erasing photorefractive scatter
Publisher: The Optical Society
Date: 13-05-2013
DOI: 10.1364/OE.21.012309
A simple external iodine stabilizer applied to 633 nm, 612 nm and 543 nm He-Ne lasers
Publisher: IOP Publishing
Date: 1995
Small gold nanoparticles as crystallization 'catalysts': Effect of seed size and concentration on Au-ZnO hetero nanoparticles
Publisher: American Chemical Society (ACS)
Date: 13-08-2015
A Monte Carlo Markov chain algorithm for a class of mixture time series models
Publisher: Springer Science and Business Media LLC
Date: 28-08-2011
Standoff Raman spectrometry for the non-invasive detection of explosives precursors in highly fluorescing packaging
Publisher: Elsevier BV
Date: 2013
DOI: 10.1016/J.TALANTA.2012.09.055
Abstract: Noninvasive standoff deep Raman spectroscopy has been utilised for the detection of explosives precursors in highly fluorescing packaging from 15m. To our knowledge this is the first time standoff deep Raman spectroscopy of concealed substances in highly fluorescing coloured packaging is demonstrated. Time-resolved Raman spectroscopy, spatially offset Raman spectroscopy and time-resolved spatially offset Raman spectroscopy have been compared to identify their selectivity towards the deep layers of a s le. The selectivity of time-resolved Raman spectroscopy towards the concealed chemical substances was found to be comparable to that of spatially offset Raman spectroscopy. However, time-resolved Raman spectroscopy did not require precise translation of the laser excitation beam onto the surface of the interrogated packaging as in the case of spatially offset Raman spectroscopy. Our results confirm that standoff time-resolved spatially offset Raman spectroscopy has significantly higher selectivity towards the deep layers of a s le when compared to the other deep Raman spectroscopy modes. The developed spectrometer was capable of detecting the concealed substances within 5s of data acquisition. By using time-resolved spatially Raman spectroscopy, a Raman spectrum that is representative of the content alone was acquired without the use of sophisticated algorithms to eliminate the spectral contributions of the packaging material within the acquired spectrum as in the case of time-resolved Raman spectroscopy and spatially offset Raman spectroscopy.
Propagation of low-intensity Gaussian fields in photorefractive media with real and imaginary intensity-dependent refractive index components
Publisher: Springer Science and Business Media LLC
Date: 23-11-2011
Nonlinear optical properties of colloidal ZnO-Au nanostructures for optical limiting applications
Publisher: IEEE
Date: 08-2016
Using pulse transit delay in Z-scan to discriminate between excited-state absorption and other nonlinear processes in ZnO nanocones
Publisher: The Optical Society
Date: 10-03-2014
DOI: 10.1364/OE.22.006222
Intensity pulsations in distributed feedback Yb:Phosphate waveguide lasers
Publisher: IEEE
Date: 08-2011
Field portable time resolved SORS sensor for the identification of concealed hazards
Publisher: SPIE
Date: 05-2012
DOI: 10.1117/12.918981
Analysis of the interactions of bright photovoltaic low-divergence soliton-like fields in unbiased self-defocusing photorefractive BaTiO 3
Publisher: SPIE
Date: 12-02-2009
DOI: 10.1117/12.807684
Combined time- and space-resolved Raman spectrometer for the non-invasive depth profiling of chemical hazards
Publisher: Springer Science and Business Media LLC
Date: 08-02-2012
DOI: 10.1007/S00216-012-5792-2
Abstract: A time-resolved inverse spatially offset Raman spectrometer was constructed for depth profiling of Raman-active substances under both the lab and the field environments. The system operating principles and performance are discussed along with its advantages relative to traditional continuous wave spatially offset Raman spectrometer. The developed spectrometer uses a combination of space- and time-resolved detection in order to obtain high-quality Raman spectra from substances hidden behind coloured opaque surface layers, such as plastic and garments, with a single measurement. The time-gated spatially offset Raman spectrometer was successfully used to detect concealed explosives and drug precursors under incandescent and fluorescent background light as well as under daylight. The average screening time was 50 s per measurement. The excitation energy requirements were relatively low (20 mW) which makes the probe safe for screening hazardous substances. The unit has been designed with nanosecond laser excitation and gated detection, making it of lower cost and complexity than previous picosecond-based systems, to provide a functional platform for in-line or in-field sensing of chemical substances.
Field propagation with nearly constant Gaussian beam parameters in unbiased self-defocusing photorefractive media
Publisher: SPIE
Date: 21-12-2008
DOI: 10.1117/12.762457
Compensating for frequency shifts in modulation transfer spectroscopy caused by residual amplitude modulation
Publisher: Elsevier BV
Date: 2008
Coherent interfaces between crystals in nanocrystal composites
Publisher: American Chemical Society (ACS)
Date: 07-09-2010
DOI: 10.1021/NN101708Q
Abstract: Numerous materials are polycrystalline or consist with crystals of different phases. However, materials consisting of crystals on the nanometer scale (nanocrystals) are not simply aggregates of randomly oriented crystals as is generally regarded. We found, that in four different materials that consist of nanocrystals of two different phases and were obtained by different approaches, the nanocrystals of different phases are combined coherently forming interfaces with a close crystallographic registry between adjacent crystals (coherent interfaces). The four materials were fabricated by (i) depositing Ag(2)O nanoparticles on titanate nanofibers, (ii) phase transition from TiO(2)(B) nanofibers to the nanofibers of mixed TiO(2)(B) and anatase phases, (iii) dehydration of the single crystal fibril titanate core coated with anatase nanocrystals, and (iv) attaching zeolite Y nanocrystals on the surface of titanate nanofibers. The finding suggests that preferred orientations and coherent interfaces generally exist in nanocrystal systems, and according to our results, they are largely unaffected by the fabrication process that was used. This is because the preferred orientations require that the engaged crystal planes from two connected crystals have the same basal spacing and that the crystals can interlock tightly at the atomic level to form thermodynamically stable interfaces. Hence it is rational that the preferred orientations and coherent interfaces dominant the nanostructures formed between the different nanocrystals and play a key role in assembling the composite nanostructures. The orientation and interfaces between crystals of different phases in mixed-phase materials are extremely difficult to determine. Nonetheless, the thermodynamic stability of the coherent interfaces allows us to apply phase-transformation invariant line strain theory to predict the preferred orientation (and thus the structure of the coherent interfaces). The theoretical predications agree remarkably with the transmission electron microscopy (TEM) analysis. This implies that we may acquire knowledge of the orientation and the interface structures in the mixed-phase materials without TEM measurement, and the knowledge is essential for comprehensively understanding properties of the many materials and processes that depend on the interfaces.
Soliton-like interactions of bright, low-power, low-divergence Gaussian fields in an unbiased self-defocusing photorefractive BaTiO3 crystal
Publisher: SPIE-Intl Soc Optical Eng
Date: 2011
DOI: 10.1117/1.3526683
Accurate measurement of the molecular thickness of thin organic shells on small inorganic cores using dynamic light scattering
Publisher: American Chemical Society (ACS)
Date: 09-01-2014
DOI: 10.1021/LA403391T
Abstract: Dynamic light scattering (DLS) has become a primary nanoparticle characterization technique with applications from material characterization to biological and environmental detection. With the expansion in DLS use from homogeneous spheres to more complicated nanostructures comes a decrease in accuracy. Much research has been performed to develop different diffusion models that account for the vastly different structures, but little attention has been given to the effect on the light scattering properties in relation to DLS. In this work, small (core size < 5 nm) core-shell nanoparticles were used as a case study to measure the capping thickness of a layer of dodecanethiol (DDT) on Au and ZnO nanoparticles by DLS. We find that the DDT shell has very little effect on the scattering properties of the inorganic core and, hence, can be ignored to a first approximation. However, this results in conventional DLS analysis overestimating the hydrodynamic size in the volume- and number-weighted distributions. With the introduction of a simple correction formula that more accurately yields hydrodynamic size distributions, a more precise determination of the molecular shell thickness is obtained. With this correction, the measured thickness of the DDT shell was found to be 7.3 ± 0.3 Å, much less than the extended chain length of 16 Å. This organic layer thickness suggests that, on small nanoparticles, the DDT monolayer adopts a compact disordered structure rather than an open ordered structure on both ZnO and Au nanoparticle surfaces. These observations are in agreement with published molecular dynamics results.
Viable Photocatalysts under Solar-Spectrum Irradiation: Nonplasmonic Metal Nanoparticles
Publisher: Wiley
Date: 07-02-2014
Abstract: Supported nanoparticles (NPs) of nonplasmonic transition metals (Pd, Pt, Rh, and Ir) are widely used as thermally activated catalysts for the synthesis of important organic compounds, but little is known about their photocatalytic capabilities. We discovered that irradiation with light can significantly enhance the intrinsic catalytic performance of these metal NPs at ambient temperatures for several types of reactions. These metal NPs strongly absorb the light mainly through interband electronic transitions. The excited electrons interact with the reactant molecules on the particles to accelerate these reactions. The rate of the catalyzed reaction depends on the concentration and energy of the excited electrons, which can be increased by increasing the light intensity or by reducing the irradiation wavelength. The metal NPs can also effectively couple thermal and light energy sources to more efficiently drive chemical transformations.
Enhancing visible-light photocatalytic performance of Au/TiO2 catalysts through light reflection-promoted optical absorption with oriented anatase mesocrystals
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D2TA09982A
Abstract: Au NPs effectively harvest light through absorption of light back-reflected from oriented TiO 2 mesocrystals supported on Ti foil. The enhanced light absorption facilitates the generation of electron–hole pairs and intensive EM fields that realizes efficient photocatalysis.
Controlling Au Photodeposition on Large ZnO Nanoparticles
Publisher: American Chemical Society (ACS)
Date: 26-05-2016
Abstract: This study investigated how to control the rate of photoreduction of metastable AuCl2(-) at the solid-solution interface of large ZnO nanoparticles (NPs) (50-100 nm size). Band-gap photoexcitation of electronic charge in ZnO by 370 nm UV light yielded Au NP deposition and the formation of ZnO-Au NP hybrids. Au NP growth was observed to be nonepitaxial, and the patterns of Au photodeposition onto ZnO NPs observed by high-resolution transmission electron microscopy were consistent with reduction of AuCl2(-) at ZnO facet edges and corner sites. Au NP photodeposition was effective in the presence of labile oleylamine ligands attached to the ZnO surface however, when a strong-binding dodecanethiol ligand coated the surface, photodeposition was quenched. Rates of interfacial electron transfer at the ZnO-solution interface were adjusted by changing the solvent, and these rates were observed to strongly depend on the solvent's permittivity (ε) and viscosity. From measurements of electron transfer from ZnO to the organic dye toluidine blue at the ZnO-solution interface, it was confirmed that low ε solvent mixtures (ε ≈ 9.5) possessed markedly higher rates of photocatalytic interfacial electron transfer (∼3.2 × 10(4) electrons·particle(-1)·s(-1)) compared to solvent mixtures with high ε (ε = 29.9, ∼1.9 × 10(4) electrons·particle(-1)·s(-1)). Dissolved oxygen content in the solvent and the exposure time of ZnO to band-gap, near-UV photoexcitation were also identified as factors that strongly affected Au photodeposition behavior. Production of Au clusters was favored under conditions that caused electron accumulation in the ZnO-Au NP hybrid. Under conditions where electron discharge was rapid (such as in low ε solvents), AuCl2(-) precursor ions photoreduced at ZnO surfaces in less than 5 s, leading to deposition of several small, isolated ∼6 nm Au NP on the ZnO host instead.
Metallic nanomesh with disordered dual-size apertures as wide-viewing-angle transparent conductive electrode
Publisher: American Chemical Society (ACS)
Date: 23-08-2016
Abstract: With the rapid development of display-related markets, transparent conductive films (TCFs) with wide viewing angles, high transmittance and low sheet resistance are in high demand. However, as a promising TCF material, metallic membranes with a submicrometer-sized periodicity pattern fabricated by currently available techniques always reveal the angle-dependent structure color which can be a major issue in the development of wide-angle viewing display-related applications. In this work, we demonstrate an Au nanomesh with disordered dual-size apertures as a novel TCF with wide viewing angles which is made via a modified nanosphere lithography technique. The as-prepared Au nanomesh film shows good optoelectronic properties (Rs = 160 Ω sq(-1), T = 80% Rs = 8 Ω sq(-1), T = 57%) that are similar to the Au nanomesh with single size apertures, while the former exhibits excellent wide-angle viewing performance. There is no obvious change in the film when the viewing angle, the light incidence angle or the orientation of substrate vary in the range of 0-90°. In contrast, a rainbow color is observed with the film with ordered single-size apertures. Electrochromic devices based on the novel metallic film show more uniform color distribution than the devices based on metallic film with ordered single-size apertures under indoor natural light irradiation. These findings demonstrate the applicability of the Au nanomesh film with dual-size apertures in enhancing display quality of high-performance optoelectronic devices.
Theoretical determination of maximum signal levels obtainable with modulation transfer spectroscopy
Publisher: Elsevier BV
Date: 10-1995
Polarization dependent photorefractive amplitude modulation production in MgO:LiNbO3 phase modulators
Publisher: IEEE
Date: 08-2011
Concealed substance identification using a defocused inverse spatially offset Raman spectrometer
Publisher: IEEE
Date: 08-2011
Narrow linewidth DFB waveguide laser fabricated via ultrafast laser inscription
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 15-12-2014
Suppression of crystallization in ZBLAN glass by rapid heating and cooling processing
Publisher: Wiley
Date: 16-01-2019
DOI: 10.1111/IJAG.13096
Reversal of degradation of information masks in lithium niobate
Publisher: Optica Publishing Group
Date: 11-08-2009
DOI: 10.1364/AO.48.004676
Abstract: We report on the reversal of degradation of information masks stored in self-defocusing lithium niobate. After a long writing time, the image degradation appears as the splitting of refractive-index patterns stored in the medium. The reversal is achieved simply by illuminating the crystal with incoherent light from a halogen l . The reversal occurs because the refractive-index changes responsible for the splitting are of a smaller magnitude and are therefore erased first during incoherent illumination. Additionally, we gain insight into the storage, degradation, and erasure dynamics using a time-dependent numerical model of the photorefractive effect in this medium. Since the data can be recovered from a degraded state in which the original data are unrecognizable, this technique could be utilized in such applications as image scrambling or encryption.
Towards non-invasive detection of concealed energetic materials infield under ambient light conditions
Publisher: SPIE
Date: 13-05-2011
DOI: 10.1117/12.886662
Near Infrared Light Induced Radical Polymerization in Water
Publisher: Wiley
Date: 06-09-2022
Abstract: We introduce a gold nanorod (AuNR) driven methodology to induce free radical polymerization in water with near infrared light (800 nm). The process exploits photothermal conversion in AuNR and subsequent heat transfer to a radical initiator (here azobisisobutyronitrile) for primary radical generation. A broad range of reaction conditions were investigated, demonstrating control over molecular weight and reaction conversion of dimethylacrylamide polymers, using nuclear magnetic resonance spectroscopy. We underpin our experimental data with finite element simulation of the spatio‐temporal temperature profile surrounding the AuNR directly after femtosecond laser pulse excitation. Critically, we evidence that polymerization can be induced through biological tissues given the enhanced penetration depth of the near infrared light. We submit that the presented initiation mechanism in aqueous systems holds promise for radical polymerization in biological environments, including cells.
Suppression effects of cooling rate on crystallization in ZBLAN glass
Publisher: Elsevier BV
Date: 02-2018
Primary wavelength standards for direct measurement of gauge blocks
Publisher: SPIE
Date: 30-09-1998
DOI: 10.1117/12.323112
Fabrication of Holographic Gratings in Photosensitive Media With a Passively Stable Sagnac Optical Arrangement
Publisher: IOP Publishing
Date: 15-05-2006
Classification in segmented regression problems
Publisher: Elsevier BV
Date: 07-2011
Trace vapour detection at room temperature using Raman spectroscopy
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3AN01522J
Abstract: A miniaturized flow-through system consisting of a gold coated silicon substrate based on enhanced Raman spectroscopy has been used to study the detection of vapour from model explosive compounds.
Mechanically Robust Tapioca Starch Composite Binder with Improved Ionic Conductivity for Sustainable Lithium-Ion Batteries
Publisher: American Chemical Society (ACS)
Date: 11-06-2020
Density of a single crystal natural silicon sphere
Publisher: IEEE
Date: 06-2008
Optical data encryption using time-dependent dynamics of refractive index changes in LiNbO3
Publisher: The Optical Society
Date: 12-08-2013
DOI: 10.1364/OE.21.019510
Supported silver nanoparticles as photocatalysts under ultraviolet and visible light irradiation
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B921696K
Transition from intensity dependent absorption to transparency in Ce:BaTiO3
Publisher: Elsevier BV
Date: 10-2008
Formation of one-dimensional capped ZnO nanoparticle assemblies at the air/water interface
Publisher: American Chemical Society (ACS)
Date: 19-08-2010
DOI: 10.1021/LA102152E
Abstract: The self-assembling behavior and microscopic structure of zinc oxide nanoparticle Langmuir-Blodgett monolayer films were investigated for the case of zinc oxide nanoparticles coated with a hydrophobic layer of dodecanethiol. Evolution of nanoparticle film structure as a function of surface pressure (π) at the air-water interface was monitored in situ using Brewster's angle microscopy, where it was determined that π = 16 mN/m produced near-defect-free monolayer films. Transmission electron micrographs of drop-cast and Langmuir-Schaefer deposited films of the dodecanethiol-coated zinc oxide nanoparticles revealed that the nanoparticle preparation method yielded a microscopic structure that consisted of one-dimensional rodlike assemblies of nanoparticles with typical dimensions of 25 × 400 nm, encased in the organic dodecanethiol layer. These nanoparticle-containing rodlike micelles were aligned into ordered arrangements of parallel rods using the Langmuir-Blodgett technique.
Direct Photocatalysis for Organic Synthesis by Using Plasmonic-Metal Nanoparticles Irradiated with Visible Light
Publisher: Wiley
Date: 22-07-2014
Abstract: Recent advances in direct-use plasmonic-metal nanoparticles (NPs) as photocatalysts to drive organic synthesis reactions under visible-light irradiation have attracted great interest. Plasmonic-metal NPs are characterized by their strong interaction with visible light through excitation of the localized surface plasmon resonance (LSPR). Herein, we review recent developments in direct photocatalysis using plasmonic-metal NPs and their applications. We focus on the role played by the LSPR of the metal NPs in catalyzing organic transformations and, more broadly, the role that light irradiation plays in catalyzing the reactions. Through this, the reaction mechanisms that these light-excited energetic electrons promote will be highlighted. This review will be of particular interest to researchers who are designing and fabricating new plasmonic-metal NP photocatalysts by identifying important reaction mechanisms that occur through light irradiation.
Comparison of nonnested asymmetric heteroskedastic models
Publisher: Elsevier BV
Date: 12-2006
The Effectiveness of Ultraviolet-C (UV-C) Irradiation on the Viability of Airborne Pseudomonas aeruginosa
Publisher: MDPI AG
Date: 21-10-2022
Abstract: Pseudomonas aeruginosa (Pa) is the predominant bacterial pathogen in people with cystic fibrosis (CF) and can be transmitted by airborne droplet nuclei. Little is known about the ability of ultraviolet band C (UV-C) irradiation to inactivate Pa at doses and conditions relevant to implementation in indoor clinical settings. We assessed the effectiveness of UV-C (265 nm) at up to seven doses on the decay of nebulized Pa aerosols (clonal Pa strain) under a range of experimental conditions. Experiments were done in a 400 L rotating s ling drum. A six-stage Andersen cascade impactor was used to collect aerosols inside the drum and the particle size distribution was characterized by an optical particle counter. UV-C effectiveness was characterized relative to control tests (no UV-C) of the natural decay of Pa. We performed 112 tests in total across all experimental conditions. The addition of UV-C significantly increased the inactivation of Pa compared with natural decay alone at all but one of the UV-C doses assessed. UV-C doses from 246–1968 µW s/cm2 had an estimated effectiveness of approximately 50–90% for airborne Pa. The effectiveness of doses ≥984 µW s/cm2 were not significantly different from each other (p-values: 0.365 to ~1), consistent with a flattening of effectiveness at higher doses. Modelling showed that delivering the highest dose associated with significant improvement in effectiveness (984 µW s/cm2) to the upper air of three clinical rooms would lead to lower room doses from 37–49% of the 8 h occupational limit. Our results suggest that UV-C can expedite the inactivation of nebulized airborne Pa under controlled conditions, at levels that can be delivered safely in occupied settings. These findings need corroboration, but UV-C may have potential applications in locations where people with CF congregate, coupled with other indoor and administrative infection control measures.
Enhancing Catalytic Performance of Palladium in Gold and Palladium Alloy Nanoparticles for Organic Synthesis Reactions through Visible Light Irradiation at Ambient Temperatures
Publisher: American Chemical Society (ACS)
Date: 08-04-2013
DOI: 10.1021/JA400527A
Abstract: The intrinsic catalytic activity of palladium (Pd) is significantly enhanced in gold (Au)-Pd alloy nanoparticles (NPs) under visible light irradiation at ambient temperatures. The alloy NPs strongly absorb light and efficiently enhance the conversion of several reactions, including Suzuki-Miyaura cross coupling, oxidative addition of benzylamine, selective oxidation of aromatic alcohols to corresponding aldehydes and ketones, and phenol oxidation. The Au/Pd molar ratio of the alloy NPs has an important impact on performance of the catalysts since it determines both the electronic heterogeneity and the distribution of Pd sites at the NP surface, with these two factors playing key roles in the catalytic activity. Irradiating with light produces an even more profound enhancement in the catalytic performance of the NPs. For ex le, the best conversion rate achieved thermally at 30 °C for Suzuki-Miyaura cross coupling was 37% at a Au/Pd ratio of 1:1.86, while under light illumination the yield increased to 96% under the same conditions. The catalytic activity of the alloy NPs depends on the intensity and wavelength of incident light. Light absorption due to the Localized Surface Plasmon Resonance of gold nanocrystals plays an important role in enhancing catalyst performance. We believe that the conduction electrons of the NPs gain the light absorbed energy producing energetic electrons at the surface Pd sites, which enhances the sites' intrinsic catalytic ability. These findings provide useful guidelines for designing efficient catalysts composed of alloys of a plasmonic metal and a catalytically active transition metal for various organic syntheses driven by sunlight.
Wavelength-resolved near infra-red light induced free-radical polymerization
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3PY01097J
An iodine stabilized laser source at two wavelengths for accurate dimensional measurements
Publisher: AIP Publishing
Date: 03-2003
DOI: 10.1063/1.1535233
Abstract: A tunable laser system is described that provides wavelength references at both 633 and 640 nm by locking to hyperfine components of molecular iodine using a simple external cell technique. The frequency uncertainty at each wavelength is less than 1 MHz and no calibration of the frequencies is required as they are both referenced to iodine transitions. Switching between references requires a simple adjustment of laser wavelength that produces no change in beam alignment. At either wavelength the laser provides more than 3 mW of unused light that is not modulated, making it useful for dimension measuring interferometry. The measurement of the diameter of silicon spheres to 2×10−8 is given as an ex le.
Deep Raman spectroscopy for the non-invasive standoff detection of concealed chemical threat agents
Publisher: Elsevier BV
Date: 05-2012
DOI: 10.1016/J.TALANTA.2012.03.053
Abstract: Deep Raman spectroscopy has been utilized for the standoff detection of concealed chemical threat agents from a distance of 15 m under real life background illumination conditions. By using combined time and space resolved measurements, various explosive precursors hidden in opaque plastic containers were identified non-invasively. Our results confirm that combined time and space resolved Raman spectroscopy leads to higher selectivity towards the sub-layer over the surface layer as well as enhanced rejection of fluorescence from the container surface when compared to standoff spatially offset Raman spectroscopy. Raman spectra that have minimal interference from the packaging material and good signal-to-noise ratio were acquired within 5 s of measurement time. A new combined time and space resolved Raman spectrometer has been designed with nanosecond laser excitation and gated detection, making it of lower cost and complexity than picosecond-based laboratory systems.
An acoustically enhanced gold film Raman sensor on a lithium niobate substrate
Publisher: Wiley
Date: 11-06-2014
DOI: 10.1002/JRS.4522
Eye-safe UV stand-off Raman spectroscopy for the ranged detection of explosives in the field
Publisher: Wiley
Date: 09-02-2015
DOI: 10.1002/JRS.4642
Dynamic control of the spatial modes in the external resonator of a semilinear phase-conjugate mirror
Publisher: Optica Publishing Group
Date: 05-1993
Nahinfrarotlicht‐induzierte radikalische Polymerisation in Wasser
Publisher: Wiley
Date: 06-09-2022
Abstract: Wir stellen eine auf Goldnanostäbchen (AuNR) basierende Methode vor, um eine radikalische Polymerisation in Wasser mit Nahinfrarotlicht (800 nm) zu induzieren. Der Prozess nutzt die photothermische Umwandlung in AuNR und die anschließende Wärmeübertragung auf einen Radikalinitiator (hier Azobisisobutyronitril) für die primäre Radikalbildung. Es wurde ein breites Spektrum an Reaktionsbedingungen untersucht, wobei die Kontrolle über das Molekulargewicht und den Reaktionsumsatz von Dimethylacrylamidpolymeren mit Hilfe der kernmagnetischen Resonanzspektroskopie nachgewiesen wurde. Wir untermauern unsere experimentellen Daten mit einer Finite‐Elemente‐Simulation des räumlich‐zeitlichen Temperaturprofils in der Umgebung der AuNR direkt nach der Anregung durch Femtosekunden‐Laserpulse. Wir weisen nach, dass die Polymerisation, aufgrund erhöhter Eindringtiefe des Nahinfrarotlichts, durch biologisches Gewebe induziert werden kann. Wir sind der Meinung, dass der vorgestellte Initiierungsmechanismus in wässrigen Systemen vielversprechend für die radikale Polymerisation in biologischen Umgebungen, einschließlich Zellen, ist.
Financial burden of caring until the end of life
Publisher: Wiley
Date: 26-10-2008
Single Frequency and Tunable Single Frequency Semiconductor Laser Systems
Publisher: Wiley
Date: 24-03-2005
Quantifying the effectiveness of ultraviolet-C light at inactivating airborne Mycobacterium abscessus
Publisher: Elsevier BV
Date: 02-2023
DOI: 10.1016/J.JHIN.2022.10.008
Abstract: Mycobacterium abscessus (MABS) group are environmental organisms that can cause infection in people with cystic fibrosis (CF) and other suppurative lung diseases. There is potential for person-to-person airborne transmission of MABS among people with CF attending the same care centre. Ultraviolet light (band C, UV-C) is used for Mycobacterium tuberculosis control indoors however, no studies have assessed UV-C for airborne MABS. To determine whether a range of UV-C doses increased the inactivation of airborne MABS, compared with no-UVC conditions. MABS was generated by a vibrating mesh nebulizer located within a 400 L rotating drum s ler, and then exposed to an array of 265 nm UV-C light-emitting diodes (LED). A six-stage Andersen Cascade Impactor was used to collect aerosols. Standard microbiological protocols were used for enumerating MABS, and these quantified the effectiveness of UV-C doses (in triplicate). UV-C effectiveness was estimated using the difference between inactivation with and without UV-C. Sixteen tests were performed, with UV-C doses ranging from 276 to 1104 μW s/cm This study provides empirical in-vitro evidence that nebulized MABS are susceptible to UV-C inactivation.
SERS substrate for detection of explosives
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2NR32409A
Abstract: A novel gold coated femtosecond laser nanostructured sapphire surface - an "optical nose" - based on surface-enhanced Raman spectroscopy (SERS) for detecting vapours of explosive substances was investigated. Four different nitroaromatic vapours at room temperature were tested. Sensor responses were unambiguous and showed response in the range of 0.05-15 μM at 25 °C. The laser fabricated substrate nanostructures produced up to an eight-fold increase in Raman signal over that observed on the unstructured portions of the substrate. This work demonstrates a simple sensing system that is compatible with commercial manufacturing practices to detect taggants in explosives which can undertake as part of an integrated security or investigative mission.
Direct photocatalysis of supported metal nanostructures for organic synthesis
Publisher: IOP Publishing
Date: 23-06-2017
Lemon balm and kidney bean intercropping: the potential for incorporating AMF for sustainable agricultural production
Publisher: Springer Science and Business Media LLC
Date: 16-04-2023
Dependence of residual amplitude noise in electro-optic phase modulators on the intensity distribution of the incident field
Publisher: IOP Publishing
Date: 24-10-2013
Analytic solutions to closed and eclipsing aperture Z-scan power transmission
Publisher: Optica Publishing Group
Date: 16-03-2022
DOI: 10.1364/JOSAB.451595
Abstract: Analytical solutions are derived using a straightforward mathematical treatment that accurately describes the power of a T E M 00 Gaussian beam transmitted through or around a finite far-field aperture after propagation though a nonlinear refractive medium. These equations are arranged as a series of transmitted power orders, which allow closed and eclipsing aperture Z -scan experiments to be analyzed analytically without requiring numerical simulation. It is shown with this formulism that the power eclipsing an obscuring aperture can be expressed through a linear relationship of the power transmitted through a closed aperture of the same dimensions, which means that the theoretical measurement accuracy of the two methods is the same. A study of the sensitivity of the solutions to nonlinear phase shifts up to 4 π shows that the peak to valley change in normalized power transmission for both closed and eclipsing aperture decreases for phases beyond 3 π / 2 , which means for large phase shifts it is difficult to determine a nonlinear refraction coefficient from peak to valley transmission measurements alone. The solutions were experimentally verified with closed and eclipsing aperture Z -scan toluene measurements undertaken over a range of aperture radii, which agreed well with previously published empirical formulas. The solutions correctly model the observed changes and asymmetries, explained here through strong s le induced focusing, in the closed aperture Z -scan trace shape.
Minimum refractometrically detectable concentrations of single atmospheric gases and simple mixtures with a Sagnac interferometer
Publisher: Optica Publishing Group
Date: 12-06-2009
DOI: 10.1364/AO.48.003481
Abstract: The minimum quantities of the nine most abundant, isolated, atmospheric gases that are detectable with a refractometer are calculated. An examination of the applicability of refractometric techniques for detecting and analyzing gaseous mixtures is discussed and a comparison made against other established techniques. Traditionally, most gas analysis performed with an interferometer is in determining the dispersion or refractivity of a known s le, presented here is the inverse approach, where refractivities are measured to determine the concentrations of particular species within a gas. The method, and experimental results for determining the minimum quantities of a particular species detectable in a mixture has been explored, as well as the complications, such as the indistinguishability of dynamic polarizabilities of different gases and the subsequent demands for accurate pressure and fringe measurements of using interferometric techniques. It is shown that the concentration of a single (isolated) gas, in units of number density, can be determined to within approximately 1-10 x 10(18) m(-3), and a mixture of the three most abundant gases, N2, O2 and Ar, to within 3.4 x 10(4) parts in 10(6) (ppm) when a minimum detectable fringe shift of lambda/100 is assumed.
Analytic solutions to closed and eclipsing aperture Z-scan power transmission: erratum
Publisher: Optica Publishing Group
Date: 05-10-2022
DOI: 10.1364/JOSAB.475242
Abstract: In our paper J. Opt. Soc. Am. B 39 , 1130 ( 2022 ) JOBPDE 0740-3224 10.1364/JOSAB.451595 there are typographical mistakes and omissions in four mathematical expressions that appear in Section 2.A of the published paper. This erratum corrects those errors to allow the normalized power transmission to be calculated correctly.
Energy Transmission of Vortex Beams Through 3rd Order Intensity Dependent Nonlinear Optical Limiters
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2021
Visible light enhanced oxidant free dehydrogenation of aromatic alcohols using Au-Pd alloy nanoparticle catalysts
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3GC41866A
Nonlinear absorption and fluorescence in ZnO and ZnO-Au nanostructures
Publisher: Wiley
Date: 04-10-2016
Enhancing Raman signal sufficiently for practical sensing applications
Publisher: OSA
Date: 2014
Using image analysis to determine ideal aperture conditions for optimal Z-scan signal quality
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2018
Photon Energy Threshold in Direct Photocatalysis with Metal Nanoparticles – Key Evidence from Action Spectrum of the Reaction
Publisher: American Chemical Society (ACS)
Date: 23-05-2017
DOI: 10.1021/ACS.JPCLETT.7B00941
Abstract: By investigating the action spectra (the relationship between the irradiation wavelength and apparent quantum efficiency of reactions under constant irradiance) of a number of reactions catalyzed by nanoparticles including plasmonic metals, nonplasmonic metals, and their alloys at near-ambient temperatures, we found that a photon energy threshold exists in each photocatalytic reaction only photons with sufficient energy (e.g., higher than the energy level of the lowest unoccupied molecular orbitals) can initiate the reactions. This energy alignment (and the photon energy threshold) is determined by various factors, including the wavelength and intensity of irradiation, molecule structure, reaction temperature, and so forth. Hence, distinct action spectra were observed in the same type of reaction catalyzed by the same catalyst due to a different substituent group, a slightly changed reaction temperature. These results indicate that photon-electron excitations, instead of the photothermal effect, play a dominant role in direct photocatalysis of metal nanoparticles for many reactions.
Asymmetric response and interaction of US and local news in financial markets
Publisher: Wiley
Date: 2005
DOI: 10.1002/ASMB.600
Possible influence of residual amplitude modulation when using modulation transfer with iodine transitions at 543 nm
Publisher: IOP Publishing
Date: 04-1998
Non-invasive depth profiling by space and time-resolved Raman spectroscopy
Publisher: Wiley
Date: 22-05-2013
DOI: 10.1002/JRS.4313
Predicting the localized surface plasmon resonances of spherical nanoparticles on a substrate: Electrostatic eigenmode method
Publisher: American Chemical Society (ACS)
Date: 05-12-2012
DOI: 10.1021/JP307510E
Accurate determination of nonlinear refraction in ZnO and Au composite nanostructures
Publisher: Optica Publishing Group
Date: 30-01-2020
DOI: 10.1364/OME.380344
Abstract: It is now well established that the nonlinear optical properties of ZnO nanoparticles can be significantly enhanced by coupling them to metallic nanoparticles. While the nonlinear absorption properties are well reported, there is large variation in the coefficients of nonlinear refraction reported in literature, largely due to simplifications made during the analysis of experimental z-scan data used to determine the coefficients. This work presents closed aperture z-scan theory which incorporates the effects of nonlinear absorption, thus providing a more accurate measure of the coefficient of nonlinear refraction. With this theory, it is shown that the coefficient of nonlinear refraction increases by an order of magnitude when ZnO is coupled to Au nanoparticles.
Semi-empirical estimation of the attenuation loss for amorphous ZBLAN glass
Publisher: Springer Science and Business Media LLC
Date: 27-07-2019
Optimizing modulation transfer spectroscopy signals for frequency locking in the presence of depleted saturating fields
Publisher: Optica Publishing Group
Date: 02-05-2008
DOI: 10.1364/AO.47.002574
Abstract: A theoretical model of modulation transfer spectroscopy (MTS) that includes pump beam depletion is presented and experimentally verified with data covering visible iodine transitions at 532, 543, and 612 nm. This model is used to determine the values for pressure, interaction length, and saturation intensity that yield maximum MTS signals for frequency locking to iodine transitions. The approach is demonstrated for iodine transitions at 532, 633, and 778 nm, with the results showing that theoretically the frequency instability scales inversely to the absorption coefficient.
Assessing and testing for threshold nonlinearity in stock returns
Publisher: Wiley
Date: 12-2005
Intensity dependent residual amplitude modulation in electro-optic phase modulators
Publisher: The Optical Society
Date: 06-2012
DOI: 10.1364/AO.51.003684
Efficient photocatalytic Suzuki cross-coupling reactions on Au–Pd alloy nanoparticles under visible light irradiation
Publisher: Royal Society of Chemistry (RSC)
Date: 26-06-2014
DOI: 10.1039/C4GC00588K
Highly compact refractive index sensor based on stripe waveguides for lab-on-a-chip sensing applications
Publisher: Beilstein Institut
Date: 25-05-2016
DOI: 10.3762/BJNANO.7.66
Abstract: In this paper we report the design and experimental realisation of a novel refractive index sensor based on coupling between three nanoscale stripe waveguides. The sensor is highly compact and designed to operate at a single wavelength. We demonstrate that the sensor exhibits linear response with a resolution of 6 × 10 −4 RIU (refractive index unit) for a change in relative output intensity of 1%. Authors expect that the outcome of this paper will prove beneficial in highly compact, label-free and highly sensitive refractive index analysis.
Spatially offset raman spectroscopy (SORS) for the analysis and detection of packaged pharmaceuticals and concealed drugs
Publisher: Elsevier BV
Date: 10-2011
DOI: 10.1016/J.FORSCIINT.2011.05.016
Abstract: Spatially offset Raman spectroscopy (SORS) is a powerful new technique for the non-invasive detection and identification of concealed substances and drugs. Here, we demonstrate the SORS technique in several scenarios that are relevant to customs screening, postal screening, drug detection and forensics applications. The ex les include analysis of a multi-layered postal package to identify a concealed substance identification of an antibiotic capsule inside its plastic blister pack analysis of an envelope containing a powder and identification of a drug dissolved in a clear solvent, contained in a non-transparent plastic bottle. As well as providing practical ex les of SORS, the results highlight several considerations regarding the use of SORS in the field, including the advantages of different analysis geometries and the ability to tailor instrument parameters and optics to suit different types of packages and s les. We also discuss the features and benefits of SORS in relation to existing Raman techniques, including confocal microscopy, wide area illumination and the conventional backscattered Raman spectroscopy. The results will contribute to the recognition of SORS as a promising method for the rapid, chemically specific analysis and detection of drugs and pharmaceuticals.
Multi-angle fluorometer technique for the determination of absorption and scattering coefficients of subwavelength nanoparticles
Publisher: The Optical Society
Date: 19-07-2016
DOI: 10.1364/OE.24.017090
CFEnetwork: The Annals of Computational and Financial Econometrics
Publisher: Elsevier BV
Date: 08-2014
Modelling Gaussian beam propagation through thick nonlinear refractive and absorptive media
Publisher: Springer Science and Business Media LLC
Date: 09-03-2016
Theoretical description of low divergence gaussian fields in self-defocusing photorefractive media
Publisher: Elsevier BV
Date: 06-2008
Mechanism of supported gold nanoparticles as photocatalysts under ultraviolet and visible light irradiation
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B917052A
Abstract: Gold nanoparticles strongly absorb both visible light and ultraviolet light to drive an oxidation reaction for a synthetic dye, as well as phenol degradation and selective oxidation of benzyl alcohol under UV light.
Sequential frequency locking of three He-Ne lasers with one external iodine stabilizer
Publisher: IOP Publishing
Date: 08-1997
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Linkage Projects - Grant ID: LP0882614
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