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PHIPS–HALO: the airborne Particle Habit Imaging and Polar Scattering probe – Part 1: Design and operation
摘要： The number and shape of ice crystals present in mixed-phase and ice clouds influence the radiation properties, precipitation occurrence and lifetime of these clouds. Since clouds play a major role in the climate system, influencing the energy budget by scattering sunlight and absorbing heat radiation from the earth, it is necessary to investigate the optical and microphysical properties of cloud particles particularly in situ. The relationship between the microphysics and the single scattering properties of cloud particles is usually obtained by modelling the optical scattering properties from in situ measurements of ice crystal size distributions. The measured size distribution and the assumed particle shape might be erroneous in case of non-spherical ice particles. There is a demand to obtain both information correspondently and simultaneously for individual cloud particles in their natural environment. For evaluating the average scattering phase function as a function of ice particle habit and crystal complexity, in situ measurements are required. To this end we have developed a novel airborne optical sensor (PHIPS-HALO) to measure the optical properties and the corresponding microphysical parameters of individual cloud particles simultaneously. PHIPS-HALO has been tested in the AIDA cloud simulation chamber and deployed in mountain stations as well as research aircraft (HALO and Polar 6). It is a successive version of the laboratory prototype instrument PHIPS-AIDA. In this paper we present the detailed design of PHIPS-HALO, including the detection mechanism, optical design, mechanical construction and aerodynamic characterization.
关键词： mixed-phase clouds,PHIPS-HALO,precipitation,ice crystals,ice clouds,optical properties,radiation properties,climate system,microphysical properties,airborne optical sensor
更新于2025-09-04 15:30:14
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Optimizing the Synthesis of Zinc-rich Gallium Zinc Oxynitrides by Combining Co-Precipitation and Moisture-Assisted Nitridation
摘要： ZnO-co-doped GaN is a promising catalyst for photocatalytic overall water splitting in the visible light range. The conventional high-temperature synthesis has the drawback that only low amounts of Zn2+ ions can be incorporated into the GaN:ZnO matrix due to a substantial loss of volatile Zn metal during the nitridation of the binary oxides in flowing NH3. By applying moisture-assisted nitridation of a co-precipitated GaZn precursor under milder conditions it was possible to significantly reduce the Zn loss during nitridation. Using a GaZn precursor with a high Zn content, GaN:ZnO nanoparticles containing high amounts of Zn were obtained. The bandgap was found to decrease nearly linearly with increasing Zn content. Concomitantly, the defect density and structural disorder increased with increasing Zn content.
关键词： Gallium zinc oxynitride,UV/Vis spectroscopy,Co-precipitation,Nitridation,Raman spectroscopy
更新于2025-09-04 15:30:14
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Effect of biocides and anionic homopolymeric inhibitors on the precipitation behavior of calcium fluoride
摘要： This paper describes the effect of biocides and of the anionic homopolymeric inhibitors on the precipitation behavior of calcium fluoride (CaF2).The efficiency of inhibitors in the presence and absence of biocides was calculated using the half-life (t1/2) approach, where 50% of the concentration has been precipitated. Conductometric and X-ray diffraction (XRD) analysis have been performed for the calcium fluoride scale minerals using three polymeric inhibitors and three biocides, which are commonly used in industrial processes. The main aim of the study was to investigate the role of anionic homopolymerspoly(acrylic acid) PAA, and of the oxidizing and non-oxidizing biocides such as; sodium hypochlorite, gluteraldehyde, tris(hydroxymethyl) nitromethane). It was found that addition of low concentration (1-10 mg/L) of the polymers (K-752, K-732 and K-702) have great inhibitory effect on the precipitation of calcium fluoride (CaF2). Their inhibition efficiency was in the order, K-752 > K-732 > K-702. The observed behaviour can be attributed to the effect of molecular weight of the polymer. The polymer having higher molecular weight shows weaker inhibiting ability. However, the oxidizing and non-oxidizing biocides have no appreciable effect on their performance and hence on the overall inhibition process.
关键词： Biocides,Precipitation,Inhibition,Calcium fluoride,Homopolymeric inhibitors
更新于2025-09-04 15:30:14
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Impact of active geomagnetic conditions on stimulated radiation during ionospheric second electron gyroharmonic heating
摘要： Recently, narrowband emissions ordered near the H+ (proton) gyrofrequency (fcH) were reported in the stimulated electromagnetic emission (SEE) spectrum during active geomagnetic conditions. This work presents new observations and theoretical analysis of these recently discovered emissions. These emission lines are observed in the stimulated electromagnetic emission (SEE) spectrum when the transmitter is tuned near the second electron gyroharmonic frequency (2fce) during recent ionospheric modification experiments at the High Frequency Active Auroral Research (HAARP) facility near Gakona, Alaska. The spectral lines are typically shifted below and above the pump wave frequency by harmonics of a frequency roughly 10% less than fcH (≈ 800 Hz) with a narrow emission bandwidth less than the O+ gyrofrequency (≈ 50 Hz). However, new observations and analysis of emission lines ordered by a frequency approximately 10% greater than fcH are presented here for the first time as well. The interaction altitude for the heating for all the observations is in the range of 160 km up to 200 km. As described previously, proton precipitation due to active geomagnetic conditions is considered as the reason for the presence of H+ ions known to be a minor background constituent in this altitude region. DMSP satellite observations over HAARP during the heating experiments and ground-based magnetometer and riometer data validate active geomagnetic conditions. The theory of parametric decay instability in multi-ion component plasma including H+ ions as a minority species described in previous work is expanded in light of simultaneously observed preexisting SEE features to interpret the newly reported observations. Impact of active geomagnetic conditions on the SEE spectrum as a diagnostic tool for proton precipitation event characterization is discussed.
关键词： stimulated electromagnetic emission,parametric decay instability,proton precipitation,HAARP,ionospheric heating
更新于2025-09-04 15:30:14
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Electro-morphological, structural, thermal and ionic conduction properties of Gd/Pr co-doped ceria electrolytes exhibiting mixed Pr3+/Pr4+ cations
摘要： Gd0.2-xPrxCe0.8O1.90, (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10) has been synthesized by means of a simple co-precipitation route based on ammonium carbonate as the precipitating agent. The as-synthesized precursors are cerium-gadolinium-praseodymium amorphous hydroxycarbonates, which are nanometric in size with highly homogeneous morphology, leading to reactive doped and co-doped nanocrystalline (≈13 nm) ceria after a mild thermal treatment (2 h at 600 °C). The obtained results highlight the very positive effect of Pr on the powders’ sintering behaviour, which favour a better densification of the final pellets, thus improving both their microstructure (with relative densities of 97–99% after sintering at 1250 °C for 3 h) and electrochemical properties (up to 1.25?10–1 S cm?1 at 800 °C for sample 6Pr) compared to the state-of-art ceria-based electrolytes. Through a comprehensive characterization, a relation was formed between the Pr content and the microstructural features of the sintered pellets and their electrical behaviour. The amount of Pr doping was investigated over a wide range and 6 mol% has been established to be optimal (possessing the lowest electronic conductivity contribution). Definitely, these results indicate that Gd0.2-xPrxCe0.8O1.90 has an excellent set of characteristics, both microstructural and electrical, and a convenient fabrication process, thus making it perfectly suitable for IT-SOFC practical applications.
关键词： Ceria-based electrolyte,IT-SOFC,Co-precipitation,Praseodymium,Nanocrystalline ceria
更新于2025-09-04 15:30:14
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Ultra-small amorphous carbon dots: preparation, photoluminescence properties, and their application as TiO2 photosensitizers
摘要： Ultra-small carbon quantum dots (s-CQDs) with excitation wavelength-independent fluorescence had been obtained by hydrothermal-followed acid precipitation method and were characterized by FT-IR, TEM, XPS, UV–Vis and XRD. It was found that as-prepared s-CQDs were amorphous spherical particles with an average diameter of 1.51 nm, and there were abundant hydroxyl and carbonyl groups on their surfaces. Moreover, fluorescence emission study found that the luminescence of s-CQDs was aroused by oxygen group decorated on its surface, and the fluorescence properties of s-CQDs were much different from those of large CQDs (l-CQDs), which showed higher quantum yield and better photoluminescence (PL) property than that of l-CQDs. The PL of s-CQDs possessed two emission centers and was exhibited to be excitation independent. When s-CQDs was used as photosensitizer for TiO2 to photocatalytic degradation of methylene blue under visible light irradiation, it showed significantly improved photocatalytic activities compared with 1-CQDs, and the degradation efficiency of methylene blue reached up to 96.6%. The high degradation efficiency was attributed to the ultra-small particle size, abundant acidic groups, and excellent optical properties of s-CQDs.
关键词： Photocatalytic degradation,Ultra-small carbon quantum dots,TiO2 photosensitizers,Photoluminescence,Hydrothermal-followed acid precipitation method
更新于2025-09-04 15:30:14
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Improved Hydrophobicity of Polydimethylsiloxane (PDMS) Coating with ZnO Nanostructures
摘要： In this present work, an environmentally safe hydrophobic cotton surface comprising of PDMS and different morphology of Zinc oxide (ZnO) nanostructures via simple dip coating method was developed. ZnO nanosphere and ZnO nanoflakes were synthesized via sol gel method while ZnO nanorods were synthesized via solution precipitation method. The precursors used to prepared ZnO nanospheres, nanoflakes and nanorods are zinc acetate dehydrate, zinc chloride and zinc nitrate tetrahydrate respectively. ZnO nanostructures were analysed using FESEM and XRD. The hydrophobic cotton surface was characterized via FT-IR and WCA analysis. A WCA of 144.15° was achieved when coating the cotton with ZnO nanoflakes (ZnO-NF:PDMS).
关键词： ZnO nanostructures,Polydimethylsiloxane,Solution precipitation method,Hydrophobicity,Sol gel method,Dip coating
更新于2025-09-04 15:30:14
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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 - Precipitation Retrieval Accuracies of the Tropics Constellation of Passive Microwave Cubesats
摘要： This paper evaluates the performance of the passive microwave spectrometer to be launched aboard the Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) for retrieving surface precipitation and hydrometeor water paths. The retrieval algorithms employ neural networks trained and evaluated using the physical reference model NCEP/WRF/TBSCAT/F(λ). Results show that TROPICS retrieved surface precipitation rates and hydrometeor water paths agree well with WRF truth. The accuracies of TROPICS retrieved daily, weekly, and monthly surface precipitation amounts are close to those of the Advanced Microwave Sounding Unit (AMSU). The TROPICS constellation will provide useful precipitation retrievals at unprecedented 30-minute temporal resolution.
关键词： CubeSat,microwave radiometry,TROPICS,AMSU,precipitation retrieval
更新于2025-09-04 15:30:14