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A spark discharge generator for scalable aerosol CVD synthesis of single-walled carbon nanotubes with tailored characteristics
摘要： We have designed and built an exhaust-free spark discharge generator for robust aerosol CVD synthesis of single-walled carbon nanotubes. The systematic study has shown the generator to provide a facile and repeatable route to precisely control the size of the catalyst particle and, therefore, carbon nanotube growth. Using a comprehensive set of methods (the analysis of differential mobility of the aerosol particles, optical spectroscopy, scanning and transmission electron microscopy, Raman spectroscopy, and atomic force microscopy) we have revealed the relation between the defectiveness, length, diameter distribution of carbon nanotubes and specific features of a generator such as electrode characteristics (breakdown voltage, composition, and current) as well as the nature of the surrounding media (carrier gas nature, flow rate). The design used has resulted in separation of the nanoparticle formation and carbon nanotube nucleation processes. This provides a mutual independence of the growth parameters and the diameter distribution of the single-walled carbon nanotubes enhancing the scalability of the process. For instance, the breakdown voltage has been shown to have nearly zero effect on diameter and length distribution of carbon nanotubes produced while strictly governing the yield. We focus here on producing specifically short carbon nanotubes (l < 500nm) of pronounced defectiveness for drug delivery and transistor applications.
关键词： single-walled carbon nanotubes,differential mobility analyzer,catalyst activation,spark-discharge generator,aerosol CVD,floating bed reactor
更新于2025-11-14 17:03:37
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A sustainable multi-function biomorphic material for pollution remediation or UV absorption: Aerosol assisted preparation of highly porous ZnO-based materials from cork templates
摘要： For the first time, highly porous ZnO-based biomorphic materials were synthesised using cork as a natural sustainable template. In the first step, waste cork powder was pyrolysed and converted into inorganic carbon. This template was then infiltrated using a novel approach employing an aerosol of zinc-containing solutions. The infiltrated powders were calcined to convert the precursors into zinc oxide. Depending on temperature, these could form either a ZnO-graphite composite material, or pure ZnO. Their morphology, porosity, microstructure and composition were characterised; their optical band gap energies, ability to adsorb and photodegrade organic pollutants and UV absorption were also assessed. When heated to 350 oC they maintained the 3D porous cork structure, producing a graphite-containing composite material, with both physical adsorption and photocatalytic activity (Eg = 3.19 eV), suitable for environmental remediation. When heated to 700 oC, the powders were pure ZnO (no graphite), and they absorbed in the UV region, hence suitable for use as sunscreen. Doped ZnO ecoceramics were also produced, using silver and aluminium. An addition of 1 mol% Ag improved photocatalysis under solar light. Conversely, adding 2 mol% Al and calcining at 700 oC deactivated photocatalysis, but maintained strong UV absorption, producing a safer sunscreen material (no generation of free radicals). This is the first time that photocatalytic or UV absorption properties of any wood-derived biomorphic material or ecoceramic have been reported.
关键词： sunscreen.,zinc oxide,biomorphic/ecoceramic,aerosol,photocatalyst
更新于2025-10-22 19:40:53
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Climatological analysis of the optical properties of aerosols and their direct radiative forcing in the Middle East
摘要： In addition to climate perturbations, various problems such as air pollution, reduction in the visibility and human health hazards were caused by atmospheric aerosols in the Middle East specifically in the last two decades. With the help of the Aerosol Robotic NETwork (AERONET), the measurement of the aerosol optical and radiative properties were carried out over seven sites in the Middle East during 2013. The analysis of the optical properties of aerosols like Single Scattering Albedo (SSA), Angstrom Exponent (AE), Aerosol Optical Depth (AOD), and Asymmetry parameter (ASY) were carried out during the study period. During spring and summer, high values of AOD and low values of AE were found in all sites except CUT-TEPAK (Limassol, Cyprus), which specified the existence of coarse mode particles and dust storms in these seasons. The AE maximum values were found in the summer and fall over CUT-TEPAK and IMS-METU-ERDEMLI(Erdemli, Turkey), whereas in other sites IASBS (Zanjan, Iran), KAUST Campus (Thuwal, Saudi Arabia), Masdar Institute (Masdar, United Arab Emirates), Mezaira (Mezaira, United Arab Emirates) and Solar Village (Riyadh, Saudi Arabia) the peak values of AE occurred in the fall and winter. The maximum values of SSA and ASY were observed in the spring and summer over all sites except over CUT-TEPAK and IMS-METU-ERDEMLI. The Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model has been used for the calculations of the Aerosol Radiative Forcing (ARF) over the selected sites. We obtained negative value of ARF at the surface, which suggesting its cooling effects because of the loss of radiation back to space due to aerosols. The averaged ARF values at the SuRFace (SRF) of the earth were -43.8 Wm-2, -31 Wm-2, -56.8 Wm-2, -61.7 Wm-2, -52.5 Wm-2, -54.9 Wm-2, and -72.2 Wm-2, over CUT-TEPAK, IASABS, IMS-METU-ERDEMLI, KAUST Campus, Masdar Institute, Mezaira and Solar Village, respectively. While the positive value of atmospheric ARF showed heating of the atmosphere.
关键词： Middle East.,Aerosol Optical Depth,SBDART,Aerosol Radiative Forcing,AERONET
更新于2025-09-23 15:23:52
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - LaSRC (Land Surface Reflectance Code): Overview, application and validation using MODIS, VIIRS, LANDSAT and Sentinel 2 data's
摘要： This paper presents a generic approach developed to derive surface reflectance over land from a variety of sensors. This technique builds on the extensive dataset acquired by the Terra platform by combining MODIS and MISR to derive an explicit and dynamic map of band ratio’s between blue and red channels and is a refinement of the operational approach used for MODIS and LANDSAT over the past 15 years. We will present the generic approach and the application to MODIS VIIRS, LANDSAT and Sentinel 2 data’s and its validation using the AERONET data [1].
关键词： aerosol,surface reflectance,validation
更新于2025-09-23 15:23:52
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Tailoring Shape and Crystallographic Phase of Copper Sulfide Nanostructures Using Novel Thiourea Complexes as Single Source Precursors
摘要： Copper sulfide thin films and nanoparticles have been prepared via aerosol assisted chemical vapour deposition and solvothermal hot injection routes, respectively. Both routes employed heterocyclic amine based benzoylthioureato-copper(II) complexes as single source precursors. Copper sulfide thin films of diverse morphologies ranging from cubic to snowy or irregular crystallites depending on the deposition temperature were observed. Powder X-ray diffraction studies of the as deposited thin films have indicated the formation of hexagonal and cubic phases of copper sulfide. In the case of the nanoparticles, Roxbyite (Cu1.75S) phase was obtained in dodecanethiol at temperatures of 150, 190 and 230 °C. However, a preferred growth of nanoparticles was observed in the presence of oleylamine whereas the roxbyite phase was obtained at temperatures of 150, 200 and 250 °C. Also transmission electron microscopy showed the formation of close to spherical, hexagonal nano-disk and rod shaped nanoparticles.
关键词： Aerosol assisted chemical vapour deposition,Nanoparticles,Heterocyclic thiourea,Copper sulfide,Thermolysis,Thin films
更新于2025-09-23 15:23:52
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Improved Cloud Screening Method for the Analysis of Sky Radiometer Measurements and Application to Asian Dust Detection
摘要： A cloud screening method employing two successive procedures of variability test and coarse mode test was developed, aiming at better elimination of cloud-contaminated data in the sky radiometer retrievals. The performance of the new cloud screening method was evaluated by examining statistical features with cloud coverage observations and lidar measurements. The variability test appeared to effectively eliminate data contaminated by relatively thick low-level clouds, whereas the coarse mode test appeared to eliminate data likely contaminated by thin cirrus-type clouds. Overall, the new method was considered to improve the current Sky Radiometer Network (SKYNET) data. The cloud screening method was then applied to dust detection from sky radiometer measurements. The detection performance was evaluated using surface synoptic observations (SYNOP) dust reports and the yellow sand index from NIES lidar measurements. It was shown that the new method helped to detect dust, effectively eliminating cloud-contaminated signals that were similar to those of the dust.
关键词： dust,cloud screening,aerosol,SKYNET
更新于2025-09-23 15:23:52
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On-line measurement of fluorescent aerosols near an industrial zone in the Yangtze River Delta region using a wideband integrated bioaerosol spectrometer
摘要： In this work, we present on-line fluorescent aerosol measurements by the wideband integrated bioaerosol spectrometer (WIBS-4A) near an industrial zone in Nanjing, a megacity in the Yangtze-River-Delta (YRD) region. The fieldwork was conducted from April 1 to May 8, 2014. A TSI. 3321 aerosol-particle-sizer (APS) was simultaneously deployed to measure the total number size distribution of aerosol with diameter from 0.8–20 μm. Both WIBS-4A and APS reported similar number concentration and temporal profiles (R2 = 0.72). However, the daily average number of potential bioaerosols was only 0.5 ± 0.2% of the total particles detected by the WIBS-4A and displayed a completely different diurnal profile from that of APS. In addition, WIBS-4A can only provide integrated fluorescent signals, which strongly limited the potential to specifically identify the bioaerosols. Accordingly, hierarchical-agglomerative-cluster-analysis (HACA) was utilized to identify and speciate the potential bioaerosols from the WIBS-4A dataset. By maximizing the total distances among all potential cluster centers, a 12-cluster solution was accepted as the optimum result. These clusters were further identified according to their fluorescent signatures, size, and morphology, i.e., non-bioaerosols, bacteria, and fungal spores and/or pollen fragments. Bacteria were the dominant bioaerosol species detected in this work. The diurnal profiles of bioaerosols correlated very well with relatively humidity (RH), reaching daily maxima around 3 AM~6 AM, indicating the presence of humidity controlled bioaerosol emission mechanism, i.e., bacteria may flourish under moderate ambient temperature, RH, and the absence of UV radiation. The size- and AF-distributions of bioaerosols indicated that bioaerosols normally varied substantially in size and assumed a rather irregular shape. Although the number concentration of bioaerosols was relatively small, most bioaerosols can efficiently serve as ice nuclei by providing rough and irregular surfaces, verified by the observation results. Therefore, WIBS-4A measurements can still be informative for investigations of bioaerosols in the atmosphere, especially when HACA method was incorporated into the data processing.
关键词： Hierarchical agglomerative cluster analysis,WIBS-4A,Ice nuclei,Cloud condensation nuclei,Primary biological aerosol
更新于2025-09-23 15:23:52
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Aerosol uncertainty assessment: an integrated approach of remote AQUA MODIS and AERONET data
摘要： The moderate resolution imaging spectroradiometer (MODIS) is one of the widely used sensors to address environmental and climate change subjects with a daily global coverage. MODIS Collection 6 aerosol products at 10-km resolution are used in this study to monitor aerosol variability and assess its uncertainty using ground-based measurements. The aerosol optical depth (AOD) is retrieved by different algorithms based on the pixel surface, determining between land and ocean. Using data collected from Sidi Salem Aerosol Robotic Network (AERONET) station, we computed the accuracy for aerosol optical depth (AOD) retrieved from MODIS aboard the AQUA satellite using two validation methods. The results show a good agreement between MODIS and AERONET data for the study period using both the algorithms. We obtained high values of the correlation coefficient. These findings indicate that MODIS data perform well over Ben Salem AERONET station and are recommended for air quality monitoring over Tunisia. The conducted validation throughout the AERONET leads to a degree of confidence that allows a deep investigation of the AOD spatial variability over Tunisia. Then, MODIS data shows high performance with good certainty to identify the principal dust sources and typical transport paths occurring on the study region.
关键词： AQUA,Remote sensing,AOD,AERONET,Aerosol,MODIS
更新于2025-09-23 15:23:52
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Investigating the Aerosol Optical Depth and Angstrom Exponent and Their Relationships with Meteorological Parameters Over Lahore in Pakistan
摘要： In the present work, AERONET (AErosol RObotic NETwork) data of 2006–2014 have been used to analyze the variations in aerosol optical depth (AOD) at 500 nm and Angstrom exponent (440/870) (AE). In order to have an in-depth knowledge of aerosol variability, we have analyzed the association of aerosol properties with the meteorological parameters such as temperature, mean sea level pressure, rainfall, dew point, and dust storm frequency. Long-term observations of MODIS-AOD are also validated with AERONET-AOD over Lahore. The peak monthly mean value of AOD is found in July (1.00 ± 0.34) with the corresponding AE value of 0.85 ± 0.29 pointing toward the fact that desert/soil dust aerosols dominated the atmosphere of Lahore. The lowest value of AOD is found in February (0.47 ± 0.26) with the corresponding AE value of 1.22 ± 0.29 representing the presence of urban/industrial aerosols in the atmosphere over Lahore. The monthly mean AE value is found to be maximum in January (1.36 ± 0.15), whereas lowest value of AE is found in June (0.55 ± 0.25). AOD shows positive correlations with temperature, dew point, relative humidity, visibility, rain and dust storm frequency, and negative with mean sea level pressure and wind speed. AE exhibits positive correlations with relative humidity and mean sea level pressure, while with temperature, dew point, visibility, rain and dust storm frequency, it shows negative correlations.
关键词： Aerosol optical depth,Angstrom exponent,Meteorological parameters,Lahore
更新于2025-09-23 15:23:52
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Estimation of spatiotemporal PM1.0 distributions in China by combining PM2.5 observations with satellite aerosol optical depth
摘要： Particulates smaller than 1.0 μm (PM1.0) have strong associations with public health and environment, and considerable exposure data should be obtained to understand the actual environmental burden. This study presented a PM1.0 estimation strategy based on the generalised regression neural network model. The proposed strategy combined ground-based observations of PM2.5 and satellite-derived aerosol optical depth (AOD) to estimate PM1.0 concentrations in China from July 2015 to June 2017. Results indicated that the PM1.0 estimates agreed well with the ground-based measurements with an R2 of 0.74, root mean square error of 19.0 μg/m3 and mean absolute error of 11.4 μg/m3 as calculated with the tenfold cross-validation method. The diurnal estimation performance displayed remarkable single-peak variation with the highest R2 of 0.80 at noon, and the seasonal estimation performance showed that the proposed method could effectively capture high-pollution events of PM1.0 in winter. Spatially, the most polluted areas were clustered in the North China Plain, where the average estimates presented a bimodal distribution during daytime. In addition, the quality of satellite-derived AOD, the robustness of the interpolation algorithm and the proportion of PM1.0 in PM2.5 were confirmed to affect the estimation accuracy of the proposed model.
关键词： Himawari-8,PM1.0,Neural network,Air pollution,Aerosol optical depth
更新于2025-09-23 15:23:52