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The phase transitions in selective laser-melted 18-NI (300-grade) maraging steel
摘要： Dilatometric studies in 18-Ni steel components fabricated by selective laser melting technique were carried out to determine the influence of heating rate on transitions occurring during the heating cycle. SLM components have been examined in controlled heating and cooling cycles. For analysis, heating of the analysed materials was carried out at heating rates of 10, 15, 20, 30 and 60 °C min?1. During the heating process, two solid-state reactions were identified—i.e. precipitation of intermetallic phases and the reversion of martensite to austenite. A simplified procedure based on the Kissinger equation was used to determine the activation energy of individual reactions. For precipitation of intermetallic phases, the activation energy was estimated 301 kJ mol?1, while the martensite to austenite reversion was determined at the activation energy 478 kJ mol?1.
关键词： Precipitation,Martensite reversion,Phase transitions,Maraging steels
更新于2025-09-23 15:21:01
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Role of Morphology of Surfactant-Free Nanoparticles in Organic Photovoltaics
摘要： Nanoparticulate (NP) ?lms and organic photovoltaic devices have been fabricated from poly(3-hexylthiophene):phenyl C61 butyric acid methyl ester (P3HT:PC61BM) NP aqueous dispersions prepared by the precipitation method. The NP inks were stable for more than 4 days, and nanoparticle organic photovoltaic (NP-OPV) devices with ef?ciency (g) of 1% were fabricated. Detailed analysis of the morphology and performance of the precipitated NP-OPV devices indicated that an optimal blend is responsible for the photocurrent and ef?ciency observed. These results were con?rmed by grazing-incidence x-ray diffraction (GIXRD) analysis, which revealed that the precipitated NPs were resistant to thermal phase segregation, allowing thermal conditioning of the NP ?lms. These results show that precipitated NPs provide a pathway to thermally stable NP-OPV devices with higher photocurrents and ef?ciencies, approaching those of optimal bulk heterojunction (BHJ) OPV devices.
关键词： ink stability,Organic photovoltaic cells (OPV),nanoparticle (NP),nanoparticle morphology,precipitation,surfactant-free
更新于2025-09-23 15:21:01
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Enhancing the performance of LARP-synthesized CsPbBr <sub/>3</sub> nanocrystal LEDs by employing a dual hole injection layer
摘要： Lead halide perovskites have been considered promising materials for optoelectronic applications owing to their superior properties. CsPbBr3 nanocrystals (NCs) with a narrow particle size distribution and a narrow emission spectrum are synthesized by ligand-assisted re-precipitation (LARP), a low-cost and facile process. In inverted CsPbBr3 NC LEDs, a dual hole injection layer (HIL) of 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile (HAT-CN)/MoO3 is introduced to enhance hole injection and transport, because HAT-CN can extract electrons easily from the hole transport layer and leave a large number of holes there. The current and power efficiencies of the optimized device with a dual HIL are 1.5- and 1.8-fold higher than those of the single HIL device. It is believed that the dual HAT-CN/MoO3 HIL effectively promotes hole injection and has promise for application in many other devices.
关键词： Ligand-assisted re-precipitation,Optoelectronic applications,Lead halide perovskites,CsPbBr3 nanocrystals,Dual hole injection layer,HAT-CN/MoO3
更新于2025-09-23 15:21:01
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Ultrathin sheetlike BiOAc0.67I0.33 solid solution with optimal energy levels and enhanced visible-light photocatalytic activity
摘要： BiO(CH3COO)xI1-x (denoted as BiOAcxI1-x) solid solutions were easily synthesized by co-precipitation method. The BiOAcxI1-x solid solutions with x = 0.67 possessed the highest visible-light photocatalytic activity for the degradation of multiple pollutants like rhodamine B (RhB), malachite green (MG) and colorless salicylic acid (SA) due to ultrathin sheetlike structures and optimal energy levels, which could e?ectively impede the re-combination of photogenerated electron-hole pairs. High separation e?ciency of charge carriers was further con?rmed by photoelectrochemical techniques. Various factors to a?ect photocatalytic performance of the BiOAcxI1-x were investigated in detail and the corresponding photocatalytic mechanism was proposed.
关键词： BiOAcI solid solution,Co-precipitation,Photocatalysis,Energy level
更新于2025-09-23 15:21:01
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Application of Colloidal Precipitation Method Using Sodium Polymethacrylate as Dispersant for TiO <sub/>2</sub> /PVDF Membrane Preparation and Its Antifouling Properties
摘要： Immobilized titanium dioxide (TiO2) nanoparticles on flat sheet polymeric membranes have been found effective for fouling reduction in recent researches. The main challenge in this field is to obtain ultrafine and stable nanodispersions. In this study, composite polyvinylidene fluoride/TiO2 (PVDF/TiO2) ultrafiltration membranes were prepared via phase inversion and colloidal precipitation method. Stable TiO2 suspensions were prepared using sodium polymethacrylate as dispersant and sonication without altering of the coagulation bath pH. The effect of different concentrations of TiO2 nanoparticles in the coagulation bath was also investigated. The membrane morphology (distribution of nanoparticles on the membrane surface) was observed by scanning electron and atomic force microscopy. Properties of the neat and the composite membranes were also characterized using energy dispersive X-ray spectroscopy and contact angle and membrane porosity measurements. The neat and the composite membranes were further investigated in terms of bovine serum albumin rejection and flux decline in cross flow filtration experiments. The results showed that the PVDF/TiO2 composite membrane using dimethylacetamide/triethyl phosphate as solvent and 0.05 g/L of TiO2 in the coagulation bath exhibits improved antifouling properties.
关键词： TiO2 nanoparticles,antifouling properties,ultrafiltration,colloidal precipitation,PVDF membrane
更新于2025-09-23 15:21:01
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Cross Validation of GPM and Ground-Based Radar in Latin America and the Caribbean
摘要： A comparison between GPM Dual-frequency Precipitation Radar and ground-based radars located in South America and the Caribbean is presented. The analysis compares radar variables from both system during overpasses of GPM over ground-based radars in the region of interest. Attenuation and bias correction is performed to ground radar data. The results show the potential of GPM to calibrate and monitor weather radars and subsequently using them for ground validation in Latin America and the Caribbean.
关键词： Ground-based weather Radar,Precipitation Measurement,Remote Sensing,GPM,DPR,Ground Validation
更新于2025-09-23 15:21:01
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Micro-transfer-printing of InP Photonic Devices to Silicon Photonics
摘要： Vertically and horizontally inhomogeneous distributions of hydrometeors are often observed in precipitating clouds. The 3-D characteristics can then cause errors in the passive microwave rainfall measurements with the current off-nadir viewing sensors’ speci?cations. This result is due to the fact that the same surface rainfall could be associated with different amounts of hydrometeors depending on the sensors’ viewing paths. In this paper, we con?rmed that the plane-parallel radiative treatment to the atmosphere leaves a notable de?ciency in the microwave radiometric signatures, particularly at the higher frequency channels for different viewing directions when largely inhomogeneous precipitating clouds are accompanied by signi?cant ice particles. The mean differences between the two brightness temperature ?elds with two opposite azimuthal viewing directions were up to approximately 40 ?K for the vertically polarized channel at 85.5 GHz in the case study. The impact of the 3-D effect on the passive microwave rainfall estimations was also examined by synthetic retrievals employing a Bayesian methodology. The results showed that the uncertainty in the rainfall estimations due to the 3-D effect depended on the viewing directions considered in the a priori information. It was also found that taking more viewing angles or the azimuth angles in the a priori information into consideration tended to moderate the retrieval difference that resulted from the different viewing directions. In addition, the retrieval uncertainty related to the 3-D effect appeared to be more signi?cant for heavy rainfall cases with large amounts of ice particles, as expected.
关键词： 3-D radiative transfer,precipitation,3-D effect,Passive microwave remote sensing
更新于2025-09-23 15:19:57
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Preparation of molecularly imprinted fluorescence sensor based on carbon quantum dots via precipitation polymerization for fluorescence detection of tetracycline
摘要： A facile and effective method was proposed to prepare the molecularly imprinted fluorescence sensor with carbon quantum dots, which were modified vinyl groups by acrylic acid on the surface. The obtained fluorescence composite material was investigated by transmission electron microscope and Fourier transform infrared spectra. After the experimental conditions were optimized, a linear range of 1.0–60 μmol L?1 was obtained and the detection limit was 0.17 μmol L?1. The novel fluorescence sensor can be successfully used to detect tetracycline in real samples. This study provides a convenient strategy for selective recognition and rapid detection of tetracycline in the complex environment.
关键词： precipitation polymerization,tetracycline,carbon quantum dots,molecularly imprinted polymers,fluorescence detection
更新于2025-09-23 15:19:57
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Laser Powder Bed Fusion of Precipitation-Hardened Martensitic Stainless Steels: A Review
摘要： Martensitic stainless steels are widely used in industries due to their high strength and good corrosion resistance performance. Precipitation-hardened (PH) martensitic stainless steels feature very high strength compared with other stainless steels, around 3-4 times the strength of austenitic stainless steels such as 304 and 316. However, the poor workability due to the high strength and hardness induced by precipitation hardening limits the extensive utilization of PH stainless steels as structural components of complex shapes. Laser powder bed fusion (L-PBF) is an attractive additive manufacturing technology, which not only exhibits the advantages of producing complex and precise parts with a short lead time, but also avoids or reduces the subsequent machining process. In this review, the microstructures of martensitic stainless steels in the as-built state, as well as the effects of process parameters, building atmosphere, and heat treatments on the microstructures, are reviewed. Then, the characteristics of defects in the as-built state and the causes are specifically analyzed. Afterward, the effect of process parameters and heat treatment conditions on mechanical properties are summarized and reviewed. Finally, the remaining issues and suggestions on future research on L-PBF of martensitic precipitation-hardened stainless steels are put forward.
关键词： 17–4 stainless steel,heat treatment,microstructure,precipitation-hardened stainless steels,ferrite,selective laser melting,building atmosphere,defects,laser powder bed fusion
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE International Conference on Consumer Electronics - Taiwan (ICCE-TW) - YILAN, Taiwan (2019.5.20-2019.5.22)] 2019 IEEE International Conference on Consumer Electronics - Taiwan (ICCE-TW) - Lightweight Image De-raining for IoT-enabled Cameras
摘要： Statistical approaches for quantitative precipitation nowcasts (QPNs) have emerged with recent advances in sensors in geostationary orbits, which provide more frequent observations at higher spatial resolutions. Advanced Meteorological Imager (AMI) onboard South Korea’s second geostationary satellite (GEO-KOMPSAT-2A), scheduled for launch in early 2018, is an example of these sensors. This paper introduces operational prototype algorithms that attempt to produce QPN products for GEO-KOMPSAT-2A. The AMI QPN products include the potential accumulated rainfall and the probability of rainfall (PoR) for a 3-h lead time. The potential accumulated rainfall algorithm consists of two major procedures: 1) identification of rainfall features on the outputs from the GEO-KOMPSAT-2A rainfall rate algorithm; and 2) tracking of these rainfall features between two consecutive images. The potential accumulated rainfall algorithm extrapolates precipitation fields every 15 min. Rainfall rates at each time step are accumulated to yield the 3-hourly rainfall. In addition, the extrapolated precipitation fields at 15-min intervals are used as inputs for the PoR algorithm, which produces the probability of precipitation during the same 3-h period. The QPN products can be classified as extrapolated features associated with precipitation. The validation results show that the extrapolated features tend to meet the designated accuracy for the prototype development stage. We also confirm a tendency for decreasing accuracy of the QPN products with increasing forecast lead time. Mitigating the dependence on lead time may remain a challenge that can be incorporated into the next generation of QPN algorithms.
关键词： probability of rainfall (PoR),quantitative precipitation nowcast,Geostationary satellite,potential accumulated rainfall
更新于2025-09-23 15:19:57