Identification of vivianite,an unusual blue pigment,in a sixteenth century painting and its implications

Vivianite, a blue pigment employed in the past practically only in Northern and Central Europe, but with very limited use, was identified in an early sixteenth century painting, stylistically with Flemish features, from a church in Portugal. The identification of this iron phosphate mineral was made by SEM‐EDS based on the atomic ratio between phosphorus and iron in layers of blue paint (area analysis) and in particles of these same layers (spot analysis). This painting, about which there is no document to prove its authorship, becomes the first case, known in detail, of a sixteenth century painting containing vivianite. Moreover, this find and the presence of a chalk ground, also identified, strongly support the hypothesis of being a Flemish painting.     

Preparation and polymerization of isopimaric acid derivatives

Isopimaric acid is a typical rosin compound and can account for 30% of the total mass of slash pine rosin. The molecular structure of isopimaric acid derivatives features an unsaturated double bond at the C13 position, opening up the possibility of their industrial polymerization. In this study, isopimaric acid (95.4%), methyl isopimarate (99.5%), and allyl isopimarate (95.1%) were prepared as highly pure monomers. New experimental results are presented and mechanisms based on the investigation of free-radical polymerization under UV irradiation are proposed. New rosin monomers for potential value-added utilization of woody biomass are also identified. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47817.     

Structural,magnetic and magnetostrictive properties of Co1-xLixFe2O4 synthesized by cathode materials of spent Li-ion batteries

In this study, we investigated the effects of substituting Li⁺ for Co²⁺ at the B sites of the spinel lattice on the structural, magnetic and magnetostrictive properties of cobalt ferrites. The Li⁺ substituted cobalt ferrites, Co_1-xLi_xFe₂O₄, with x varying from 0 to 0.7 in 0.1 increments, were synthesized with a sol-gel auto-combustion method using the cathode materials of spent Li-ion batteries. X-ray diffraction analysis revealed that all the Co_1-xLi_xFe₂O₄ nanopowders had a single-phase spinel structure and the lattice parameters decreased with increasing Li⁺ content, which can be proved by slight shifts towards higher diffraction angle values of the (311) peak. Field emission scanning electron microscopy was used to observe the fractured inner surface of the sintered cylindrical rods and the increased porosity resulted in a decreased magnetostriction. The oxidation states of Co and Fe in the cobalt ferrite samples were examined by X-ray photoelectron spectroscopy. High resolution transmission electron microscopy micrographs showed that most particles were roughly spherical and with sizes of 25–35?nm. Li⁺ substitution had a strong effect on the saturation magnetization and coercivity, which were characterized with a vibrating sample magnetometer. The Curie temperature was reduced due to the decrease in magnetic cations and the weakening of the exchange interactions. The magnetostrictive properties were influenced by the incorporation of Li⁺ at the B sites of the spinel structure and correlated with the changes in porosity, magnetocrystalline anisotropy and the cation distribution.     

某高校既有建筑室内人员相关VOCs目标污染物的实测分析

为研究高校既有建筑室内人群散发对室内VOCs的影响，对高校不同人群样本的教室及会议室两类典型人群密集房间，共82个人群样本对象进行了VOCs采样分析，得到不同实际场景下的人员相关的VOCs浓度水平，并对其潜在的影响因素进行分析。结果表明，共确认了29种与室内人员相关的高检出率且较高浓度值的物质，包括芳香族化合物9种，烷烯烃类9种，酮类和醛类8种，醇酯类以及卤化物3种，并得到主要VOCs物质的浓度水平和I/O比。对影响因素的统计分析表明，室内人员密度、季节和房间类型对不同VOCs物质存在显著性影响，其中季节性因素对目标VOCs污染物影响最为广泛，其次是房间类型与室内人员密度。该研究可为进一步了解人员密集室内VOCs污染现状及控制策略提供一定的科学参考。     

Functionalized graphene oxide nanosheets with unique three-inone properties for efficient and tunable antibacterial applications

Developing antibiotics-independent antibacterial agents is of great importance since antibiotic therapy faces great challenges from drug resistance.Graphene oxide(GO)is a promising agent due to its natural antibacterial mechanisms,such as sharp edgemediated cutting effect.However,the antibacterial activity of GO is limited by its negative charge and low photothermal effect.Herein,the amino-functionalized GO nanosheets(AGO)with unique three-in-one properties were synthesized.Three essential properties(positive charge,strong photothermal effect,and natural cutting effect)were integrated into AGO.The positive charge(30 mV)rendered AGO a strong interaction force with model pathogen Streptococcus mutans(330 nN).The natural cutting effect of 100 ng·mL^-1AGO caused 27%loss of bacterial viability after incubation for 30 min.Most importantly,upon the near-infrared irradiation for just 5 min,the three-in-one properties of AGO caused 98%viability loss.In conclusion,the short irradiation period and the tunable antibacterial activity confer the three-in-one AGO a great potential for clinical use.     

Tensor Q-rank: new data dependent definition of tensor rank

Machine Learning - Recently, the $${ Tensor}~{ Nuclear}~{ Norm}~{ (TNN)}$$ regularization based on t-SVD has been widely used in various low tubal-rank tensor recovery tasks. However, these models...     

0.88C-1.2Si-0.75Mn-2Al高强度电缆铠装钢用盘条的试制

采用中高碳成分添加低密度元素Si、Al进行轻量化的设计思路设计了试验钢的化学成分,试验钢采用50 kg真空感应炉冶炼。利用金相显微镜、SEM扫描电镜和力学性能检测设备对试制后的Φ6 mm盘条进行了显微组织观察、珠光体片层间距的测量和屈服强度、抗拉强度、延伸率的检验。结果表明:盘条在600℃等温2 h后的金相显微组织为铁素体+珠光体的混合组织,珠光体的片层间距为(126±5) nm,屈服强度大于1 183 MPa、抗拉强度大于1 425 MPa、延伸率大于10%,其力学性能满足电缆用铠装钢的技术要求。     

基于ＰＩＤ控制算法的直流微网容错控制方法研究

构建直流微网容错控制对象模型，调节直流微电网的输出回路参数；以输出功率、直流微网的 参考电压、弱电网下系统惯性响应特征等为约束参量，构建直流微网容错控制目标函数，在不同电网强度下 进行直流微网容错控制的参数自整定性调节，采用无功环比例积分控制方法进行直流微网容错寻优分析， 建立模糊 ＰＩＤ控制模型，采用变结构的模糊 ＰＩＤ控制方法进行直流微网容错控制过程中的自适应加权学习 和误差反馈调节，实现直流微网容错控制改进设计。仿真结果表明，采用该方法进行直流微网控制的容错 性能较好，输出稳定性较强，具有较好的直流微网输出增益。     

带有蓄热型直接冷凝式加热板的空气源热泵系统性能研究

针对现有的空气源热泵冬季供热系统，提出了一种使用新型蓄热型直接冷凝式加热板（RHP）的空气源热泵供热系统，并测试了RHP的热性能和系统的运行特性，同时分析了系统的效率和经济性。实验结果表明，在39℃的冷凝温度下，RHP的热容量高达1044 W，RHP的蓄热量大于1000 kJ。在室外空气温度为8℃时，系统COP高达3.7。此外，对于20 m²的居住房间而言，该系统的供暖初始投资成本和总运行成本分别为3174.7 CNY和510.7 CNY，在居住建筑冬季供暖领域具有较大的竞争力。