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2022 1

2011 2

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材料 1

超细化 1

钢铁 1

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Graft copolymerization of -isopropylacrylamide with 3-(methacryloxy)propyl trimethoxysilane on ultrafine

ZHANG Liping, ZHU Yi, NI Caihua

《化学科学与工程前沿（英文）》 2008年第2卷第3期页码 242-247 doi: 10.1007/s11705-008-0043-y

摘要： Thermosensitive core-shell particles were synthesized through graft copolymerization of -isopropylacrylamide with [ 3-(methacryloxy) propyl]trimethoxysilane (MPT) coupled on the surface of ultrafine silica beads. The copolymerization was carried out using polyvinyl alcohol as a surfactant, water and cyclohexanol as mixed solvent, and 2,2′-azobis(isobutyronitrile) as an initiator. The effect of surfactant concentration and the composition of the mixed solvent on the graft rate were investigated. The structure of modified silica was confirmed by infrared spectra. Differential scanning calorimetry (DSC) has revealed the thermosensitivity of the particles. The thermosensitive particles were used as packing materials of high performance liquid chromatography (HPLC) columns for separating naphthalene derivatives. Satisfactory separation was obtained by controlling the temperature of the column. In contrast, the packing material of silica-MPT has no such separation efficiency due to the lack of thermosensitivity. The effect of the composition of the mobile phase on the separating efficiency was also investigated. The temperature-controlled separation was effective only when the water content was higher than 90% (v/v) in the water-methanol mobile phase. The mechanism for the temperature-controlled separation is attributed to a polarity change of poly(-isopropylacrylamide) which undergoes volume phase transition on the silica surface as the temperature increases.

关键词： undergoes water-methanol surfactant concentration copolymerization chromatography

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Preparation of ultrafine α-AlO using precipitation-azeotropic distillation method

XIAO Jin, QIN Qi, ZHOU Feng, CHEN Yanbin, WAN Ye

《机械工程前沿（英文）》 2008年第3卷第2期页码 226-231 doi: 10.1007/s11465-008-0029-y

摘要： Ammonium aluminum carbonate hydroxide (AACH) was prepared by a precipitation-azeotropic distillation method, which uses aluminum sulfate as the Al source and ammonium carbonate as the precipitant. Then, AACH was calcined into ultrafine ?-AlO powder. The factors that influence the dispersion property of ultrafine ?-AlO powder are discussed in this paper, such as the methods of adding materials, surfactant, and drying methods. The changes of the structure and property of ultrafine alumina in the thermal treatment process are also studied. The morphological structure and properties of AACH are characterized by DTA/TGA, SEM, XRD, and ICP measurements. The results show that ultrafine ?-AlO powder with a uniform particle size and well-distributed property can be synthesized only after aluminum sulfate atomizes into ammonium carbonate, proper amount of PEG1000 is added as the dispersant, and the product is treated by azeotropic distillation. The phase transformation of alumina during the calcination process can be described as amorphous AlO → ?-AlO → ?-AlO → ?-AlO. The crystal grain size and density of ultrafine alumina powder increase with the increase of the calcination temperature. After AACH has been calcined at 1200°C for 2 h, the ultrafine ?-AlO with uniform particle size, spherical shape, and more than 99.97% purity is obtained and its powder is well dispersed.

关键词： calcination temperature spherical AACH carbonate hydroxide ammonium carbonate

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Ultrafine Fe-modulated Ni nanoparticles embedded within nitrogen-doped carbon from Zr-MOFs-confined conversion

《化学科学与工程前沿（英文）》 2022年第16卷第7期页码 1114-1124 doi: 10.1007/s11705-021-2087-1

摘要： Improvement of the low-cost transition metal electrocatalyst used in sluggish oxygen evolution reaction is a significant but challenging problem. In this study, ultrafine Fe-modulated Ni nanoparticles embedded in a porous Ni-doped carbon matrix were produced by the pyrolysis of zirconium metal-organic-frameworks, in which 2,2′-bipyridine-5,5′-dicarboxylate operating as a ligand can coordinate with Ni²⁺ and Fe³⁺. This strategy allows formation of Fe-modulated Ni nanoparticles with a uniform dimension of about 2 nm which can be ascribed to the spatial blocking effect of ZrO₂. This unique catalyst displays an efficient oxygen evolution reaction electrocatalytic activity with a low overpotential of 372 mV at 10 mA·cm^–2 and a small Tafel slope of 84.4 mV·dec^–1 in alkaline media. More importantly, it shows superior durability and structural stability after 43 h in a chronoamperometry test. Meanwhile, it shows excellent cycling stability during 4000 cyclic voltammetry cycles. This research offers a new insight into the construction of uniform nanoscale transition metals and their alloys as highly efficient and durable electrocatalysts.

关键词： metal-organic framework pyrolysis ultrafine Fe-modulated Ni nanoparticles oxygen evolution reaction

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钢铁材料组织超细化处理工艺研究进展

陈蕴博,张福成,褚作明,张继明,曹国华,吴玉萍

《中国工程科学》 2003年第5卷第1期页码 74-81

摘要：

综述了钢铁材料在组织超细化技术方面的研究成果，阐述了各种超细化技术的适用条件，介绍了近期这方面的研究结果。

关键词：钢铁材料超细化

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Development of a cloud condensation nuclei (CCN) counter using a laser and charge-coupled device (CCD) camera

Mikyung PARK, Jinkwan OH, Kihong PARK

《环境科学与工程前沿（英文）》 2011年第5卷第3期页码 313-319 doi: 10.1007/s11783-011-0346-y

摘要： A continuous flow streamwise thermal gradient cloud condensation nuclei (CCN) counter with an aerosol focusing and a laser-charge-coupled device (CCD) camera detector system was developed here. The counting performance of the laser-CCD camera detector system was evaluated by comparing its measured number concentrations with those measured with a condensation particle counter (CPC) using polystyrene latex (PSL) and NaCl particles of varying sizes. The CCD camera parameters (e.g. brightness, gain, gamma, and exposure time) were optimized to detect moving particles in the sensing volume and to provide the best image to count them. The CCN counter worked well in the particle number concentration range of 0.6–8000 #·cm and the minimum detectable size was found to be 0.5 μm. The supersaturation in the CCN counter with varying temperature difference was determined by using size-selected sodium chloride particles based on K?hler equation. The developed CCN counter was applied to investigate CCN activity of atmospheric ultrafine particles at 0.5% supersaturation. Data showed that CCN activity increased with increasing particle size and that the higher CCN activation for ultrafine particles occurred in the afternoon, suggesting the significant existence of hygroscopic or soluble species in photochemically-produced ultrafine particles.

关键词： aerosol cloud condensation nuclei (CCN) counter ultrafine particle

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Dilution sampling and analysis of particulate matter in biomass-derived syngas

Xiaoliang WANG, Curtis ROBBINS, S. Kent HOEKMAN, Judith C. CHOW, John G. WATSON, Dennis SCHUETZLE

《环境科学与工程前沿（英文）》 2011年第5卷第3期页码 320-330 doi: 10.1007/s11783-011-0347-x

摘要： Thermochemical biomass gasification, followed by conversion of the produced syngas to fuels and electrical power, is a promising energy alternative. Real-world characterization of particulate matter (PM) and other contaminants in the syngas is important to minimize damage and ensure efficient operation of the engines it powers and the fuels created from it. A dilution sampling system is demonstrated to quantify PM in syngas generated from two gasification plants utilizing different biomass feedstocks: a BioMax 15 Biopower System that uses raw and torrefied woodchips as feedstocks, and an integrated biorefinery (IBR) that uses rice hulls and woodchips as feedstocks. PM mass concentrations in syngas from the IBR downstream of the purification system were 12.8–13.7 μg·m , which were significantly lower than the maximum level for catalyst protection (500 μg·m ) and were 2–3 orders of magnitude lower than those in BioMax 15 syngas (2247–4835 μg·m ). Ultrafine particle number concentration and PM chemical constituents were also much lower in the IBR syngas than in the BioMax 15. The dilution sampling system enabled reliable measurements over a wide range of concentrations: the use of high sensitivity instruments allowed measurement at very low concentrations (~1 μg·m ), while the flexibility of dilution minimized sampling problems that are commonly encountered due to high levels of tars in raw syngas (~1 g·m ).

关键词： dilution source sampling syngas characterization biomass gasification ultrafine particles