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Hydrophilic Sulfonated 2,9-Diamide-1,10-phenanthroline Endowed with a Highly Effective Ligand for Separation of Americium(III) from Europium(III): Extraction, Spectroscopy, and Density Functional Theory Calculations
No full textThe design and development of a water-soluble heterocyclic ligand are believed to be an alternative way for improving the separation efficiency of actinides from lanthanides. Herein, we designed and synthesized a novel hydrophilic multidentate ligand: disulfonated N,N'-diphenyl-2,9-diamide-1,10-phenanthroline (DS-Ph-DAPhen) with soft and hard donor atoms, as a masking agent in aqueous solutions for Am(III) separation. The combination of N,N,N',N'-tetraoctyldiglycolamide in kerosene and DS-Ph-DAPhen in aqueous phases could separate Am(III) from Eu(III) across a range of nitric acid concentrations with very high selectivity. The coordination behaviors of Eu(III) with DS-Ph-DAPhen in aqueous solutions were studied by UV-vis titration, electrospray ionization mass spectrometry, and Fourier transform infrared spectra. The results indicated that Eu(III) ions could form both 1:1 and 1:2 complexes with the DS-Ph-DAPhen ligand in aqueous solution. Density functional theory calculation suggests that there are more covalent characters for Am-N bonds than that for Eu-N bonds in the complexes, which supports the better selectivity of the DS-Ph-DAPhen ligand toward Am(IU) over Eu(III). This work demonstrates a feasible alternative approach to separating trivalent actinides from lanthanides with high selectivity
Microwave Synthesis of Eco-friendly Nitrogen Doped Carbon Dots for the Corrosion Inhibition of Q235 Carbon Steel in 0.1 M HCl
No full textIn this work, nitrogen doped carbon dots (NCDs) were prepared with citric acid monohydrate (CA center dot H2O) and ethanolamine (EA) via microwave method. In combination with electrochemical techniques, weight loss and SEM, it is found that nitrogen doping in carbon dots effectively suppresses the corrosion of Q235 carbon steel in HCl solution owing to the presence of pyrrolic N in NCDs. Especially for NCDs (1:10), the optimum inhibition efficiency is about 89% after 1 h of immersion in 0.1 M HCl solution with 500 ppm of concentration. By further calculation, the Delta G(a)(ds)(0) value for NCDs (1:10) is -26.65 kJ. mol(-1), indicating the adsorption of NCDs on Q235 carbon steel surface involves both chemisorption and physisorption. In addition, NCDs still remain superior corrosion inhibition performance with the prolonged immersion time and ascending temperature
A Probable Origin of Dibenzothiophenes in Coals and Oils
No full textTo probe the possibility of thiophenolate as an origin of dibenzothiophenes (DBTs) and establish the detailed chemical transformations from thiophenolate to DBTs, the thermal degradation of thiophenolate has been carried out at various temperatures. The characterizations of both gaseous products and solid residues indicate that DBTs together with benzene, diphenyl sulfide, and diphenyl disulfide are the major degradation products. The presence of benzene supports that the thermal degradation of thiophenolate begins with the homolysis of Ar-H bonds. The subsequent hydroarylation followed by the elimination and cyclization reactions facilely generates DBTs. The transformation of thiophenolate to DBTs is chemically simple and highly geochemically feasible. It readily unifies the chemical pathways involved in the generation of DBTs from thiophenolate and that of dibenzofurans from phenolate in nature
Simple method for preparing nanometer thick Ti3C2Tx sheets towards highly efficient lubrication and wear resistance
No full textMXene, as a two-dimensional material with excellent properties, has been applied in many fields. However, there is little attention paid to the preparation methods of MXene nanosheets. Herein, we report a novel and simple method for preparing Ti3C2Tx nanosheets by using alternate pressure (AP)assisted, where the yield can achieve 42.4% and the thickness of nanosheet is about 2 nm. Moreover, the presence of hydrophilic functional groups on the surface made Ti3C2Tx suitable to be used as water lubricating additives, which displays highly efficient lubrication (similar to 34.74%) and wear resistance (similar to 45.58%) ability compared with pure water. Our work provides not only a new strategy to yield Ti3C2Tx nanosheets, but also an exploration of their tribological behaviors as water lubrication nanoadditive
Influences of Ag and In Alloying on Microstructure and Mechanical Properties of Sn-58Bi Solder
No full textAg (2.0 wt.%) and In (1.5 wt.%) were alloyed into Sn-58Bi eutectic solder, and the individual and combined influences of Ag and In on the microstructure, microhardness, and impact toughness of the SnBi solder were investigated. The results reveal that the microstructures of the SnBiAg, SnBiIn, and SnBiAgIn alloyed solders are coarser than that of the SnBi eutectic solder. Fine Ag3Sn particles are formed in the SnBiAg and SnBiAgIn solders, while small regions of In-rich phases appear in the SnBiIn and SnBiAgIn solders. The microhardness of the three alloyed solders are higher than the SnBi solder, and the Sn-rich phases in the alloyed solders show higher nanohardness, while the nanohardness of the Bi-rich phases with Ag and In addition changes little. The impact toughness of the SnBiAg, SnBiIn, and SnBiAgIn solders are observed to be higher than the SnBi solder, especially in the case of the SnBiAgIn solder. The improvement in ductility of the Sn-rich phase induced by the In solution, and the strengthening effect from the Ag3Sn particles are predicated to be the reason for the increase in impact toughness. The fracture surfaces demonstrate that plastic deformation of the SnBiAgIn solder during the impact process is more obvious. Overall, the combined addition of Ag and In can increase the microhardness and impact toughness of SnBi eutectic solder
航天功能防护涂层设计与调控
No full text随着航空航天技术的不断发展,航天材料在使用过程中会面临更加复杂苛刻的服役环境,研究出具有高硬度、高耐磨性、高耐腐蚀性等不同防护功能的涂层材料成为当前的研究重点。本文系统归纳和评述了润滑涂层、耐磨涂层与耐蚀涂层材料的研究进展,主要包括DLC薄膜、MoS2薄膜、氮化物涂层、石墨烯基涂料等。在此基础上并探讨了复合、梯度多层、纳米多层等结构设计方法和工艺技术及对涂层性能的增强机制。指出航天功能防护涂层未来将向着通过跨尺度结构设计,综合多种防护机理制备出超长寿命的航天功能防护涂层的方向发展
量子粒子群优化核极限学习机的船舶变压器故障诊断
No full text船舶变压器是船舶电力系统的关键部件,变压器故障易导致电力系统异常甚至引发船体及生命安全事故.针对基本智能算法故障诊断模型的局限性,文章采用寻优能力强搜索效率高的QPSO优化KELM建立船舶变压器故障诊断模型.采用UCI数据集对SVM、ELM、KLEM、PSO-KELM 和 QPSO-KELM 进行对比实验,结果表明 QPSO-KELM具有更好的分类性能和计算效率.最后,通过船舶变压器真实故障数据集对QPSO-KELM进行测试分析,测试集和训练集的平均正确率分别达92.15%和97.65%,标准差分别为3.75%和1.42%,充分证明了 QPSO-KELM具有优秀的诊断精度和算法稳定性,对各类船舶具有一定的实际应用价值
碳化硅陶瓷浆料基3D打印研究进展
No full text碳化硅陶瓷由于具有优异的热学、力学、化学性质,被广泛应用于国民生产生活中。然而,传统的成型方法存在精度低、难以制备复杂形状等问题,已不能满足制造业的需要。增材制造为此提供了新的发展方向。本文综述了目前以浆料形式3D打印SiC陶瓷材料的进展,对比了DIW、SLA、DLP、TPP技术在制造碳化硅陶瓷材料方面的优缺点,为选择制备方法提供了参考;还综述了四种方法制备过程中存在的问题,并为此总结了一些解决方案
Ir-MO_x/Al_2O_3硝基芳烃加氢性能研究
No full text采用正丁基锂快速还原法合成了双金属IrM(M=Ni、Fe和Co)纳米颗粒,并以其为前体在氧化铝载体上经过原位煅烧和选择性还原,制得具有明确Ir-MO_x杂化界面结构的Ir-MO_x/Al_2O_3催化剂。结果表明,相比Ir/Al_2O_3催化剂,Ir-MO_x/Al_2O_3在对氯硝基苯和对硝基苯乙酮选择性加氢制备氨基芳烃的反应中均展现了显著的活性和选择性的增强。在所有Ir基催化剂中,Ir-CoO_x/Al_2O_3具有最高的活性和选择性,这归因于Ir和CoO_x间的强相互作用力。Ir-CoO_x/Al_2O_3在10余种取代硝基芳烃选择性加氢反应中均展现了高的活性和选择性,展现了广泛的底物普适性。经过5次循环实验,Ir-CoO_x/Al_2O_3的活性和选择性均未发生明显变化,这表明合成的催化剂具有稳定的结构
高导热环氧复合材料的制备与研究
No full text在抽滤石墨烯纳米片过程中引入球形氧化铝,构建仿"豌豆荚"氧化铝-石墨烯二元多孔结构,并制备氧化铝-石墨烯-二元结构增强环氧树脂复合材料,测试其导热性能,分析仿"豌豆荚"氧化铝-石墨烯二元结构增强环氧树脂导热性能的机理。结果表明:水平排列的石墨烯在球形氧化铝作用下部分发生取向转变,呈现仿"豌豆荚"结构,其中的石墨烯为环氧复合材料在面内和面外方向提供了高效的热传输通道,极大地增强了环氧复合材料的导热性能。当石墨烯含量为12.1%,氧化铝含量为42.4%时,复合材料在面外和面内方向上的导热系数分别达到13.3 W/(m·K)和33.4 W/(m·K)。该仿"豌豆荚"氧化铝-石墨烯二元结构在提高环氧树脂导热系数方面效果显著,在电子封装领域具有潜在的应用前景