Emissive Particles Research Articles

Solution of short term integrated hydrothermal-solar-wind scheduling using sine cosine algorithm

The combined scheduling of hydro, thermal and hybrid energy (i.e., wind and solar) is attracting more and more attention nowadays. This paper explores the contribution of renewable energy sources in the traditional hydrothermal scheduling problem in order to overcome the prevailing issues like high generation cost and more emissive particles of fuel. This paper presents a new wind-solar based generation scheduling model that reduces the aforementioned issues. The proposed hydrothermal-solar-wind scheduling (HTSWS) model is very effective. It can reduce the price rate of generation and different emissive particles of fuel of the traditional scheduling model. A solution approach i.e., robust sine cosine algorithm (SCA) is employed to determine the minimum generation cost and fuel emission based best generating schedule for traditional scheduling problem. The same approach has been carried out in the context of the suggested HTSWS problems. The different control parameters of the SCA have been properly utilized to balance the exploration and the exploitation phases. These parameters lead to determination of the near-optimal global solution. The results show that the combined application of renewable sources and hydrothermal units benefit both economic and emission goals of the utility houses with operating costs and pollutant emissions falling by 10% and 64%, respectively. Here, another two powerful algorithms (i.e., backtracking search algorithm and whale algorithm) have also been applied to determine the minimum values of generation cost, emission, and combined generation cost-emission. Effectiveness and robustness of the proposed algorithm have been presented by comparing the SCA based results with other established latest algorithms for the considered problems.

Experimental investigation of the effect of Al2O3 nanoparticles as additives to B20 blended biodiesel fuel: Flame characteristics, thermal performance and pollutant emissions

Palm oil biodiesel has been identified as a renewable energy source with a huge potential to replace liquid fossil fuels in the future. The current experimental work investigates the effect of using Al2O3 nanofuel produced by adding Al2O3 nanoparticles to 20 % blend of palm oil biodiesel with diesel fuel on the flame characteristics, radiation, temperature and pollutant emissions in an oil burner. A homogeneous suspension was prepared from Al2O3 nanoparticles, of the concentration of 500 ppm, in B20 blended biodiesel fuel. The Infrared Radiation (IR) of the flame, the flame temperature, luminosity, radiative heat flux and CO and NOx pollutant emissions were measured and compared with those of B20 fuel. The results indicate that Al2O3 nanoparticles enhance the evaporation rate of nanofuel droplets and shift the maximum flame temperature to the upstream region. Al2O3 nanoparticles favor scattering of heat over heat absorption, which accelerates flame heat transfer and decreases its temperature. Nevertheless, Al2O3 nanoparticles improve soot particles nucleation and surface growth and increase the highly emissive intermediate soot particles in the flame reaction zone. These intermediate soot particles enhance the luminosity and IR and total radiation heat transfer of the flame. The enhancement rate for average flame radiation of B20 blend fuel was as much as 10 % and higher concentrations of nanoparticles led to a substantial increase in the radiation heat flux. However, they cause an increase in the CO emission from 48 to 62 ppm which is in the standard level. Finally, the use of the nanofuel instead of B20 fuel decreases the NOx emission by 11 %.

In Situ Incorporation of Hydrophobic Emissive Complexes in Monodisperse Copolymer Particles via Surfactant-free Emulsion Polymerization

Iridium complex-incorporated monodisperse particles are prepared via surfactant-free emulsion polymerization. For this process, a vinyl-substituted iridium complex (IrV) is synthesized and copolymerized with 4-vinylpyridine (4VP) and methyl methacrylate in an aqueous phase. Toluene is then used as a cargo solvent to transfer the IrV through the aqueous phase in the form of minidroplets. The amphiphilicity of 4VP enhances the transfer efficiency and prevents self-quenching of the copolymerized iridium complexes. The iridium complexes copolymerized in the particles show good photostability for more than 6 months and ∼3.6 times the enhanced photoluminescence quantum yield because of the scattering-induced light extraction effect of the particles. Moreover, phosphorescent three-dimensional photonic crystals (3D PCs) with different photonic band gaps are fabricated by adjusting the size of the emissive monodisperse particles. The phosphorescence of the 3D PC is tuned according to the position of the photonic band gap to reduce the full width at half-maximum by ∼24 nm.

Gram-Scale Synthesis and Kinetic Study of Bright Carbon Dots from Citric Acid and Citrus japonica via a Microwave-Assisted Method.

Tracking dynamic cellular processes necessitates fluorescent materials that are photostable, biocompatible, water-soluble, nanosized, and nontoxic. In this study, highly fluorescent carbon dots (CDs) were produced from cheap and readily available sources, citric acid (CA) and Philippine citrus (Citrus japonica Thunb.) or calamansi juice (CJ) via a microwave-assisted method. A number of synthetic conditions were investigated systematically to optimize the preparation of CDs from CA and CJ. The formation mechanism, surface chemistry, and photoluminescence of CA-based CDs (CA-CDs) and CJ-based CDs (CJ-CDs) were evaluated after each stage of pyrolysis in detail using different characterization techniques, such as dynamic light scattering, diffusion-ordered spectroscopy, atomic force microscopy, ζ potential, X-ray diffraction, Fourier transform infrared spectroscopy, 1H and 13C nuclear magnetic resonance spectroscopy, and absorption/emission spectroscopy. Gram-scale pyrolysis of CA with ethylenediamine (EDA) and CJ with EDA were carried out to provide CA-CDs (CA-18) within 18 min total pyrolysis time at 97% yield and CJ-CDs (CJ-14) within 14 min total pyrolysis time at 7% yield. Aqueous suspensions of CA-18 and CJ-14 CDs gave comparable bright blue luminescence at 462 nm. CA-CDs were shown to be nontoxic for mung beans up to 2 mg/mL, whereas CJ-CDs with higher surface negative charges inhibited growth above 0.5 mg/mL. This study demonstrates that bright CA- and CJ-CDs can be produced in gram-scale quantities using inexpensive methods. The size, amount, and extent of EDA incorporation are important in contributing to the formation of highly emissive particles.

A novel configuration of natural gas diffusion burners to enhance optical, thermal and radiative characteristics of flame and reduce NOx emission

A novel, simple and feasible method was proposed for increasing intermediate soot concentration and enhancing thermal and radiative characteristics of natural gas flame. In the method, based on pyrolysis technique, a portion of natural gas, as the secondary gas injection rate, was directly injected into the flame to create high temperature and emissive intermediate soot particles. The portion of the fuel dedicated to secondary injection rate varied in the range of 20–55%. The flame structure, axial temperature, soot concentration and radiation flux were examined and compared with those resulted from a prevalent burner. Also, the optical properties of intermediate soot particles were studied by BOMEM FTIR, IR flame photography and TES-1332A digital luminance meter. The results indicated that natural gas molecules injected into the flame were dominantly pyrolyzed into soot particles. These highly luminous emissive particles enhance the total flame emissivity and radiation. Moreover, considering exhaust emission limits, there was an optimum secondary injection rate (40%), which, besides enhancing the radiation of flame, maintained the emission of CO pollutant and UHC lower than the standard values. Furthermore, in the pyrolysis process absorption of heat from flame reduces maximum flame temperature and consequently NOx emission by 35% in the optimum case.

Simple strategies towards bright polymer particles via one-step staining procedures

In order to develop simple and versatile procedures for the preparation of red emissive particles, various one-step swelling procedures for the loading of fluorophores into nanometer- and micrometer-sized polystyrene particles were systematically assessed. Parameters studied for model dyes from common dye classes include the composition of the swelling medium, dye charge and polarity, dye concentration, and particle surface chemistry. The dye loading procedures were compared based upon the efficiency of dye incorporation, fluorescence intensity, and colloidal stability of the resulting particles as well as the absence of dye leaking as determined by absorption and fluorescence spectroscopy, flow cytometry, and measurements of zeta potentials. In addition, for the first time, the influence of the amount of incorporated dye on the absolute fluorescence quantum yield and brightness of the fluorescent particles was investigated for selected chromophores in differently sized particles using a custom-made calibrated integrating sphere setup. Our results demonstrate the general suitability of these one-step loading procedures for efficient particle staining with neutral, zwitterionic, and charged fluorophores like oxazines, coumarines, squaraines, xanthenes, and cyanines emitting in the visible and near infrared. Dye polarity was identified as a suitable tool to estimate the loading efficiency of fluorophores into these polymer particles.

A new continuous fluorometric assay for acetylcholinesterase activity and inhibitor screening with emissive core–shell silica particles containing tetraphenylethylene fluorophore

Emissive core-shell silica particles with tetraphenylethylene moieties were prepared and characterized. Fluorescence quenching was observed for the silica particles upon addition of compound 2 (Dabcyl-ACh). This was attributed to the electrostatic interaction between the silica particles and 2 and the resulting photoinduced energy transfer between them. After incubation with AChE, the fluorescence intensity started to increase. The fluorescence enhancement became more significant when the concentration of AChE was higher. The reaction kinetic parameters for AChE were successfully estimated with the silica particles and 2. These results reveal that the ensemble of the silica particles and 2 can be utilized for AChE assay. Moreover, the fluorescence spectra of the ensemble of the silica particles and 2 containing AChE were also measured after further addition of either neostigmine or tacrine which are typical inhibitors of AChE. The results manifest that the ensemble of the emissive silica particles and 2 is also useful for screening the inhibitors of AChE.

Using Magnetic RAM to Build Low-Power and Soft Error-Resilient L1 Cache

Due to its great scalability, fast read access, low leakage power, and nonvolatility, magnetic random access memory (MRAM) appears to be a promising memory technology for on-chip cache memory in microprocessors. However, the write-to-MRAM process is relatively slow and results in high dynamic power consumption. Such inherent disadvantages of MRAM make researchers easily conclude that MRAM can only be used for low-level caches (e.g., L2 or L3 cache), where cache memories are less frequently accessed and slow write to MRAM can be more easily compensated using simple architectural techniques. By developing a hybrid cache architecture, this paper attempts to show that, with appropriate architecture design, MRAM can also be used in L1 cache to improve both the energy efficiency and soft error immunity. The basic idea is to supplement the MRAM L1 cache with several small SRAM buffers, which can substantially mitigate the performance degradation and dynamic energy overhead induced by MRAM write operations. Moreover, the proposed hybrid cache architecture is also an efficient solution to protect cache memory from radiation-induced soft errors, as MRAM is inherently invulnerable to emissive particles. Simulation results show that, with only less than 2% performance degradation, the proposed design approach can reduce the power consumption by up to 76.1% on average compared with the traditional SRAM L1 cache. In addition, the architectural vulnerability factor of L1 data cache is reduced from 28.3% to as low as 0.5%.

Dually fluorescent silica nanoparticles

The cationic dyes 9-aminoacridine (9AA) and safranine (Sf) were entrapped into silica spheres of about 0.2μm diameter prepared by modified Stöber method. The fluorescent materials are investigated by steady-state and time-resolved emission, in addition of confocal fluorescence microscopy. Silica particles containing 9-aminoacridine (SP9AA) and safranine (SPSf) or both dyes (SPSf9AA) are emissive particles. When both dyes are present in the same particle but loaded in sequential stages 9AA emission is quenched as a consequence of energy transfer from 9AA (donor) to Sf (acceptor). This result suggests that particle growing processes where the acceptor is incorporated first into the core do not prevent donor/acceptor pairs to be close due to an overlay of the concentration gradients of both dyes in a radial core-shell like distribution.

Level-of-detail rendering of large-scale irregular volume datasets using particles

This paper describes a level-of-detail rendering technique for large-scale irregular volume datasets. It is well known that the memory bandwidth consumed by visibility sorting becomes the limiting factor when carrying out volume rendering of such datasets. To develop a sorting-free volume rendering technique, we previously proposed a particle-based technique that generates opaque and emissive particles using a density function constant within an irregular volume cell and projects the particles onto an image plane with sub-pixels. When the density function changes significantly in an irregular volume cell, the cell boundary may become prominent, which can cause blocky noise. When the number of the subpixels increases, the required frame buffer tends to be large. To solve this problem, this work proposes a new particle-based volume rendering which generates particles using metropolis sampling and renders the particles using the ensemble average. To conform the effectiveness of this method, we applied our proposed technique to several irregular volume datasets, with the result that the ensemble average outperforms the sub-pixel average in computational complexity and memory usage. In addition, the ensemble average technique allowed us to implement a level of detail in the interactive rendering of a 71-million-cell hexahedral volume dataset and a 26-million-cell quadratic tetrahedral volume dataset.

Improvement of particle-based volume rendering for visualizing irregular volume data sets

We present a technique for previewing large-scale irregular volume datasets using an improved particle-based volume rendering (PBVR) technique. Volume rendering of irregular grid volume data is considerably more complicated than that of regular grid data, since the sampling and compositing processes, which must be done in visibility order, are not straightforward. In our original PBVR, rendering involves generating and projecting sub-pixel-size, opaque, and emissive particles without visibility ordering. To make it easier to preview large-scale irregular volume datasets, we improve our original PBVR technique in two respects. The first is that we exploit its scalability to develop a cell-by-cell particle generation technique. The second is that we reduce the memory cost of the frame buffer using a pixel-by-pixel superimposing technique. To measure the effectiveness of our proposed method, we apply it to huge irregular volume datasets composed of 71 mega hexahedral cells or 1 giga tetrahedral cells.

Particle-based multiple irregular volume rendering on CUDA

In this paper, we describe an improved particle-based volume rendering (PBVR) technique for previewing a large irregular volume dataset using the CUDA architecture. This technique allows for opaque and emissive particles to render translucent volumes without visibility sorting. Our GPU acceleration of PBVR provides the multi-volume rendering feature while remaining compatible with both regular and irregular volumes. We also reduce the memory cost required for storing all sub-pixel values by proposing a pixel repetition technique for a large sub-pixel level. By adjusting the repetition level, we achieved a very smooth level of detail (LOD) control for trading quality for speed. Our work demonstrates a full-detail rendering rate from 5 to 10 fps for irregular volume data with mega-scale cell numbers on an NVIDIA GeForce 8800GTS.

Photoactivation of Silver‐Exchanged Zeolite A

Clusters of silver atoms and ions have attracted the interest of scientists because of their pronounced catalytic and emissive properties. To prevent aggregation of the clusters into larger particles, stabilization in gas matrices at cryogenic temperatures, or in scaffolds such as polyphosphates, DNA, peptides or polymers at ambient temperature, has been suggested. Alternatively, zeolites have been proposed to stabilize small ionic silver clusters. The molecular dimensions of the zeolite cages and channels prevent aggregation into larger nanoparticles (because of steric reasons) while the net negative charge of the zeolite lattice, the coordinating properties of the lattice oxygen atoms, and the presence of additional cations play a crucial role in stabilizing cationic clusters and unstable intermediates during reduction. Reduction of silver in zeolites is usually a bulk process that requires reductants, such as hydrogen gas or sodium borohydride, but also g irradiation and visible light can cause reduction. One of the most studied systems is silver-exchanged zeolite A (LTA topology), and several models have been proposed to explain the nature and location of the silver clusters formed in this zeolite upon reduction. Aside from their catalytic properties, oligonuclear silver clusters show particularly bright and stable luminescent properties. However, the existing fluorescence studies about Ag clusters in zeolites are limited to the excitation and emission spectra of bulk powder samples. Here, we report on bright fluorescent (spots in) individual silverexchanged zeolite 3A crystals obtained upon photoactivation using a focused UV irradiation on a fluorescence microscope. Photoactivation of silver has been demonstrated for nanoscale Ag2O particles (and interpreted as a photoreduction process). In our study, the emissive silver material is confined within a zeolite framework, which results in a better control of the type and location of the emissive species formed upon UV irradiation. Silver-cluster-loaded crystals are technologically very attractive—for example, as secondary light sources in fluorescence lamps—because of their high emission intensity, their excellent photostability upon UV irradiation, and their large Stokes shift. Moreover, the space-resolved selective activation of the emission intensity may have important applications in data storage. The emissive zeolite particles used herein were prepared by exchanging zeolite 3Awith (8 1)wt%Ag (fromAgNO3 solutions), followed by heating for one day at 450 8C (see the Supporting Information). The enhanced emission exhibited by the silver-exchanged zeolites after the thermal treatment has been ascribed to two possible causes: 1) to the formation of charge-transfer complexes between the partially (de)hydrated silver ions and the oxygen atoms in the zeolite lattice or 2) to the emissive properties of autoreduced oligoatomic silver clusters that may be formed during the high-temperature treatment. Although this report focuses on the photoactivation of thermally treated Ag zeolites, control experiments performed on not thermally activated Ag zeolites (dried at 110 8C) show an analogous photoactivation behavior (see the supporting Information). Figure 1a(1),b(1) shows typical confocal scanning images of a heat-treated Ag-containing zeolite crystal (roughly 3 ? 3 mm in size) taken under a confocal microscope using a picosecond-pulsed 375 nm excitation source (doubled Ti:Sapphire, Spectra Physics; see the Supporting Information). Figure 1a and 1b were taken at excitation intensities of 10 and 20 Wcm , respectively. Zeolite crystals that were not treated thermally exhibited an emission ten-times-weaker than that of the thermally treated samples. The confocal approach in combination with the pinhole in the emission path (see the Supporting Information) allows the collection of photoemission data from selected parts inside the crystals. Diffraction-limited bright spots can be generated at specific domains inside an individual crystal by simply focusing a low-power UV laser at the target position; for instance, in the crystal shown in Figure 1a, three individual spots were selectively activated by irradiation during [*] Dr. Y. Antoku, Dr. M. Sliwa, S. Smout, Prof. Dr. J. Hofkens, Dr. T. Vosch Department of Chemistry Katholieke Universiteit Leuven Celestijnenlaan 200F, 3001 Heverlee (Belgium) Fax: (+32)1632-7989 E-mail: tom.vosch@chem.kuleuven.be

Time-resolved microscopic imaging of the laser-induced forward transfer process

Laser-induced forward transfer (LIFT) technique is available for the fabrication of micro-sized thin film. In this paper, the LIFT process of gold film was investigated by the microscopic two-dimensional laser induced fluorescence (2D-LIF). The dynamic behavior of the gold atoms and emissive particles were observed in vacuum and atmospheric air. Characteristic behavior was observed for different species. The atoms flew with the fastest speed of more than 2 km/s. The influence of ablation laser energy, film thickness, and the presence of the the substrate on the dynamics of the species are reported.