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Domino Reaction for the Sustainable Functionalization of Few-Layer Graphene
摘要： The mechanism for the functionalization of graphene layers with pyrrole compounds was investigated. Liquid 1,2,5-trimethylpyrrole (TMP) was heated in air in the presence of a high surface area nanosized graphite (HSAG), at temperatures between 80 °C and 180 °C. After the thermal treatments solid and liquid samples, separated by centrifugation, were analysed by means of Raman, Fourier Transform Infrared (FT-IR) spectroscopy, X-Rays Photoelectron Spectroscopy (XPS) and 1H-Nuclear Magnetic Resonance (1H NMR) spectroscopy and High Resolution Transmission Electron Microscopy (HRTEM). FT-IR spectra were interpreted with the support of Density Functional Theory (DFT) quantum chemical modelling. Raman findings suggested that the bulk structure of HSAG remained substantially unaltered, without intercalation products. FT-IR and XPS spectra showed the presence of oxidized TMP derivatives on the solid adducts, in a much larger amount than in the liquid. For thermal treatments at T ≥ 150 °C, IR spectral features revealed not only the presence of oxidized products but also the reaction of intra-annular double bond of TMP with HSAG. XPS spectroscopy showed the increase of the ratio between C(sp2)N bonds involved in the aromatic system and C(sp3)N bonds, resulting from reaction of the pyrrole moiety, observed while increasing the temperature from 130 °C to 180 °C. All these findings, supported by modeling, led to hypothesize a cascade reaction involving a carbocatalyzed oxidation of the pyrrole compound followed by Diels-Alder cycloaddition. Graphene layers play a twofold role: at the early stages of the reaction, they behave as a catalyst for the oxidation of TMP and then they become the substrate for the cycloaddition reaction. Such sustainable functionalization, which does not produce by-products, allows us to use the pyrrole compounds for decorating sp2 carbon allotropes without altering their bulk structure and smooths the path for their wider application.
关键词： infrared spectroscopy,Density Functional Theory,pyrrole compounds,quantum chemical modelling,graphene layers,Functional Groups
更新于2025-09-23 15:23:52
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A mathematical model and iterative inversion for fluorescent optical projection tomography
摘要： Solving the fluorophore distribution in a tomographic setting has been difficult because of the lack of physically meaningful and computationally applicable propagation models. This study concentrates on the direct modelling of fluorescence signals in optical projection tomography (OPT), and on the corresponding inverse problem. The reconstruction problem is solved using emission projections corresponding to a series of rotational imaging positions of the sample. Similarly to the bright field OPT bearing resemblance with the transmission X-ray computed tomography, the fluorescent mode OPT is analogous to X-ray fluorescence tomography (XFCT). As an improved direct model for the fluorescent OPT, we derive a weighted Radon transform based on the XFCT literature. Moreover, we propose a simple and fast iteration scheme for the slice-wise reconstruction of the sample. The developed methods are applied in both numerical experiments and inversion of fluorescent OPT data from a zebrafish embryo. The results demonstrate the importance of propagation modelling and our analysis provides a flexible modelling framework for fluorescent OPT that can easily be modified to adapt to different imaging setups.
关键词： weighted Radon transform,optical projection tomography,fluorescence tomography,beam modelling,iterative reconstruction
更新于2025-09-23 15:23:52
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A Corrugated Plate Photocatalytic Reactor for Degradation of Waterborne Organic Contaminants
摘要： A UV-C/titanium dioxide (TiO2) plate coated photocatalytic reactor using a corrugated frame system was designed for water borne organic contaminant degradation. The anticipated advantages of using the corrugated layout include a larger photocatalytic surface area per unit volume and improved photocatalytic activity. The water distribution system was designed to assist effective interactions among the water pollutant, photocatalyst, and photons. The degradation of a methylene blue solution, as a model water contaminant, was carried out at room temperature (22 °C) at different concentrations and flowrates. With an 11 mg/L methylene blue solution, 70 % was degraded within the first 10 min using TiO2 coated corrugated plates, whereas under the same conditions the degradation rate was only 12 % for a corrugated reactor without a catalyst coating, and 4 % for a no-plate reactor. The methylene blue degradation was described by the Langmuir-Hinshelwood model, and the apparent photonic efficiency of the corrugated arrangement was found to be in the range of 1.53–2.83 % when half the initial concentration was degraded. The local area specific rate of energy absorption (LASREA) profile over the plates was determined from a model developed based on UV-C light irradiation distribution and plate configuration. Light intensity measurements were carried out and were found to correlate with this model. A set of corrugated plate photocatalytic reactors with different geometries, but with the same coated area, were then analyzed and absorbed UV light intensities were integrated to determine the best geometry.
关键词： corrugated photocatalytic reactor,light absorption modelling,reaction modelling
更新于2025-09-23 15:22:29
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The Comparison of the Photocatalytic Performance Shown by TiO <sub/>2</sub> and TiO <sub/>2</sub> /WO <sub/>3</sub> Composites— A Parametric and Kinetic Study
摘要： Kinetic and mechanistic related approaches for mostly titania were intensively studied in the literature. However, combined modelling and kinetic studies are few. Therefore, the present work focuses on modelling the dependence of the degradation kinetics of two model compounds (salicylic acid—SA and methyl orange—MO) on Evonik Aeroxide P25, hydrothermally prepared hierarchical TiO2 and P25/WO3 nanostars, obtained also by hydrothermal crystallization. The obtained individual semiconductors and the composites were characterized using XRD, DRS, SEM, while the photocatalytic degradation of the model pollutants were carried out varying the catalyst load, the initial pollutant concentration and incident light intensity. It was found that the degradation kinetics were independent from the hierarchical nature of the material, while significant dependencies of the degradation efficiency was found from the previously mentioned investigation parameters. All these parametric interdependences were successfully studied and a kinetic model was proposed for both bare TiO2 and TiO2/WO3 composite systems.
关键词： Degradation,Salicylic Acid,Methyl Orange,Kinetic Modelling,Composite Materials
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Radar (RADAR) - Brisbane, Australia (2018.8.27-2018.8.31)] 2018 International Conference on Radar (RADAR) - Predicting Phased Array Radar Performance Through Modelling
摘要： Modelling and simulation can reduce risk associated with complex radar system development because design choices can be validated before any hardware is developed. Models can also be used to accelerate algorithm development for existing radar systems. This paper describes the modelling results for two phased array radar designs: an MTI radar and a MIMO radar. These systems were modelled and then tested with radar data generated with commercially available radar hardware. The performance results for both models and the hardware-fed processing are analyzed and compared.
关键词： Radar Modelling,MTI Radar,MIMO Radar,Radar Simulation
更新于2025-09-23 15:22:29
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[IEEE 2018 2nd International Conference on Telematics and Future Generation Networks (TAFGEN) - Malaysia (2018.7.24-2018.7.26)] 2018 2nd International Conference on Telematics and Future Generation Networks (TAFGEN) - Modelling of Different Types of SOA Characteristics
摘要： An investigation of gain, optical power, and amplified spontaneous emission (ASE) noise characteristics of different types of semiconductor optical amplifier (SOA) operating in the conventional (C-) band is carried out. The types of SOAs include linear, nonlinear and in-line SOA that are customized configuration through OptiSystem software. These SOAs are further simulated in MATLAB using a numerical steady-state model to determine and evaluate their performance. The results showed that the linear SOA has the most ideal and distinct characteristics, as compared to the nonlinear and in-line SOAs rendering it more suitable as gain medium in the multiwavelength fiber laser (MWFL) application.
关键词： modelling,linear and nonlinear types,semiconductor optical amplifier,multiwavelength fiber laser
更新于2025-09-23 15:22:29
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A unified framework for plasma data modelling in dynamic Positron Emission Tomography studies
摘要： Objective: Full quantification of dynamic PET data requires the knowledge of tracer concentration in the arterial plasma. However, its accurate measurement is challenging due to the presence of radiolabeled metabolites and measurement noise. Mathematical models are fitted to the plasma data for both radiometabolite correction and data denoising. However, the models used are generally not physiologically informed and not consistently applied across studies even when quantifying the kinetics of the same radiotracer, introducing methodological variability affecting the results interpretation. The aim of this study was to develop and validate a unified framework for the arterial data modelling to achieve an accurate and fully-automated description of the plasma tracer kinetics. Methods: The proposed pipeline employs basis pursuit techniques for estimating both radiometabolites and parent concentration models from the raw plasma measurements, allowing the resulting algorithm to be both robust and flexible to the different quality of data available. The pipeline was tested on four PET tracers ([11C]PBR28, [11C]MePPEP, [11C]WAY-100635 and [11C]PIB) with continuous and discrete blood sampling. Results: Compared to the standard procedure, the pipeline provided similar fit of the parent fraction but yielded a better description of the total plasma radioactivity, which in turn allowed a more accurate fit of the tissue PET data. Conclusion: The new method showed superior fits compared to the standard pipeline, for both continuous and discrete arterial sampling protocol, yielding to better description of PET data. Significance: The proposed pipeline has the potential to standardize the blood data modeling in dynamic PET studies given its robustness, flexibility and easiness of use.
关键词： Kinetic modelling,Positron Emission Tomography,Input function,Receptor imaging
更新于2025-09-23 15:22:29
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Optical Wireless Communication Based Indoor Positioning Algorithms: Performance Optimisation and Mathematical Modelling
摘要： In this paper, the performance of the optimal beam radius indoor positioning (OBRIP) and two-receiver indoor positioning (TRIP) algorithms are analysed by varying system parameters in the presence of an indoor optical wireless channel modelled in line of sight configuration. From all the conducted simulations, the minimum average error value obtained for TRIP is 0.61 m against 0.81 m obtained for OBRIP for room dimensions of 10 m × 10 m × 3 m. In addition, for each simulated condition, TRIP, which uses two receivers, outperforms OBRIP and reduces position estimation error up to 30%. To get a better understanding of error in position estimation for different combinations of beam radius and separation between light emitting diodes, the 90th percentile error is determined using a cumulative distribution frequency (CDF) plot, which gives an error value of 0.94 m for TRIP as compared to 1.20 m obtained for OBRIP. Both algorithms also prove to be robust towards change in receiver tilting angle, thus providing flexibility in the selection of the parameters to adapt to any indoor environment. In addition, in this paper, a mathematical model based on the concept of raw moments is used to confirm the findings of the simulation results for the proposed algorithms. Using this mathematical model, closed-form expressions are derived for standard deviation of uniformly distributed points in an optical wireless communication based indoor positioning system with circular and rectangular beam shapes.
关键词： position estimation,channel modelling,raw moments,optical wireless communication,indoor positioning system,cumulative distribution frequency,standard deviation
更新于2025-09-23 15:22:29
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Experimental investigation and thermo-mechanical modelling for tool life evaluation of photopolymer additively manufactured mould inserts in different injection moulding conditions
摘要： There is a growing interest for integrating additive manufacturing (AM) technology in different manufacturing processes such as injection moulding (IM) due to the possibility of achieving shorter manufacturing times and increased cost effectiveness. This paper evaluates IM inserts fabricated by the AM vat photopolymerisation method. The inserts are directly manufactured with a photopolymer material, integrated on an injection moulding tool and subsequently used for IM. Therefore, particular attention has to be paid in order to develop the soft tooling process chain and the IM experimental procedure as detailed in this study. Different combinations of IM parameters are investigated in this work in order to determine the influence of the various process settings on the inserts’ performance (lifetime, crack propagation, consistency of the mould surface features). The mould inserts were analysed by three-dimensional optical metrology and evaluated with regard to the different surface features that were affected by the IM process. A three-dimensional thermo-mechanical with phase change model for the analysis of the effects of the IM process on the additive manufactured tools was accomplished in the FE software COMSOL Multiphysics. The potential causes for the insert failure are identified both by means of the IM experiments and the numerical model. The developed model could also predict the thermally induced deformations produced in the mould and identify where this phenomenon would eventually lead to defects in the shape of the parts. The influence of three different temperatures of the insert at 25 °C, 50 °C and 100 °C on the failure of the insert was investigated. Also a detailed discussion about the solidification and temperature changes is given.
关键词： Finite element modelling,Vat photopolymerization,Injection moulding,Soft tooling,Additive manufacturing
更新于2025-09-23 15:22:29
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Fabrication, Modelling and Assessment of Hybrid 1-D Elastic Fabry Perot Microcavity for Mechanical Sensing Applications
摘要： 1-D multilayer dielectric films consisting of seven pairs of SiO2 and TiO2 alternating layers are deposited on a SiO2 substrate using the radio frequency sputtering technique. The thicknesses of the film layers are chosen to reflect the visible radiation around 650 nm. An elastic microcavity layer made of Polydimethylsiloxane was sandwiched between two Bragg reflectors. A fabrication process was then developed for elastic microcavity in order to tailor the thickness, establish the surface planarity and to increase reproducibility of the samples. Optical transmittance of the single Bragg reflector and the microcavity were both simulated and measured. A comparison between measurement data and Transfer Matrix Method calculations shows a favourable correlation. Furthermore, in order to assess the suitability of the microcavity as a force sensor, transmittance measurements were carried out as a function of the applied forces. The change in the elastic microcavity thickness due to applied forces resulted in cavity resonance peak shifts proportional to the applied forces.
关键词： Optical Characterization and Modelling,Silica and Titania,1D Elastic Photonic Crystal,Mechanical Sensor,RF sputtering,PDMS
更新于2025-09-23 15:22:29