Metallic Nanoparticle-Enabled Sensing of a Drug-of-Abuse: An Attempt at Forensic Application

γ-Hydroxybutyric acid (GHB) functions as a depressant on the central nerve system and serves as a pharmaceutical agent in the treatment of narcolepsy and alcohol withdraw. In recent years, GHB has been misused as a recreational drug due to its ability to induce euphoric feelings. Moreover, it has gained increasing attention as a popular drug of abuse that is frequently related to drug-facilitated sexual assaults. At the moment, detection methods based on chromatography exhibit extraordinary sensitivity for GHB sensing. However, such techniques require complicated sample treatment prior to analysis. Optical sensors provide an alternative approach for rapid and simple analysis of GHB samples. Unfortunately, currently reported probes are mostly based on hydrogen bonding to recognize GHB, and this raises concerns about, for example, the lack of specificity. In this work, we report a bioinspired strategy for selective sensing of GHB. The method is based on specific enzyme recognition to allow highly selective detection of GHB with minimum interference, even in a complex sample matrix (e. g., simulated urine). In addition, the result can be obtained by either quantitative spectroscopy analysis or colorimetric change observed by the naked-eye, thus demonstrating its potential application in drug screening and forensic analysis.     

热压烧结制备Cu/FeCoCr复合材料的显微组织及热物理性能

利用相图计算的CALPHAD方法和超音雾化制粉技术,在CuFeCoCr体系中设计并制备了一系列微米级复合粉体。通过热压烧结方法在烧结温度为950℃,烧结压力为45 MPa的工艺条件下成功获得块体复合材料。研究了块体复合材料中Cu含量对显微组织,热导率,热膨胀系数以及显微硬度的影响。结果表明:CuFeCoCr块体复合材料均由fcc富铜相和fcc富铁钴铬相组成。该系列复合材料经600℃时效处理8 h后,其热膨胀系数变化范围为5.83×10-6~10.61×10-6 K-1,热导率变化范围为42.17~107.53 W·m-1·K-1。其中Cu55(Fe0.37Cr0.09Co0.54)45复合材料表现出良好的综合性能,即其热膨胀系数和热导率分别为9.08×10-6K-1和91.09 W·m-1·K-1,与电子封装半导体材料的热膨胀系数相匹配。     

AZ31镁合金薄板经不同累积应变的连续弯曲变形后的显微组织与成形性能

对AZ31镁合金板材进行不同累积应变的连续弯曲变形及退火处理,随后对显微组织与力学性能的变化进行了研究。结果表明:经不同累积应变的连续弯曲变形后,镁合金板材的显微组织中没有发现孪晶,退火后,板材表层的晶粒异常长大,粗晶层的厚度随着累积应变的增加而增加,并且镁合金板材的织构朝RD方向偏转,偏转角度随累积应变的增加而增大;与原始板材相比,连续弯曲变形及退火处理使镁合金板材呈现出较好的室温成形性能(杯突值由2.3 mm提高到4.9 mm,提高了~113%),这主要归因于基面织构的改善使镁合金板材的r值减小与n值增大。     

Synthesis of high-entropy diboride nanopowders via molten salt-mediated magnesiothermic reduction

Powder synthesis is critical for implementing the wide applications of high-entropy diborides (HEBs). However, the low-temperature synthesis of HEB powders was rarely reported. Herein, the low-temperature synthesis of the single-phase HEB nanopowders via molten salt-mediated magnesiothermic reduction (MMR) method was reported for the first time. The results showed that the as-synthesized nanopowders consisted of the single-phase HEBs and their average particle sizes are in the range of 28-56 nm. Meanwhile, they possessed the good compositional homogeneity and the low-content oxygen impurity in the range of 4.13-6.12 at%. In addition, their formation mechanism could be well interpreted by a classical MMR growth process.     

Controllable layer-by-layer assembly based on brucite and alginates with the assistance of spray drying and flame retardancy influenced by gradients of alginates

With the aim of tailoring and controlling surface assembly, multifunctional flame retardants (FRs) were obtained based on depositing alginates and silane coupling agents on brucite via the spray-drying-assisted layer-by-layer assembly technique. The assembly was controllable in both structure and gradient mass. Two series of FRs were named CuFR1-3 and NiFR1-3 based on the assembly content of metal alginates. With the assistance of spray drying, good compatibility between FRs and ethylene-vinyl acetate (EVA) was obtained, resulting in better mechanical properties. Meanwhile, the FRs improved flame retardancy and smoke suppression when used in EVA composites. With 55 wt % loading, composites with CuFR3 and NiFR1 passed UL 94 V-0 rating, while those with brucite were not rated. The peak of heat release rate decreased by 51.7 and 49.3% while the residue increased by 9.8 and 11.9%, respectively. The FRs also reduced the smoke and CO production rates. For the two series of FRs, the relationship between FR efficiency and alginate contents is different. The CuFRs assembled more copper alginates and exerted better flame retardancy caused by lower catalytic graphitization. NiFRs exerted a higher catalyzing efficiency at low assembly content. However, at high assembly content, the catalytic graphitization effect would decrease by thermally oxidized degradation leading to excess nickel alginates. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 47570.     

空间红外大口径折射式低温镜头设计与验证

针对目标探测类空间红外相机大范围成像、高灵敏度探测、高精度定位等应用需求,文中提出采用像方远心光路和低温光学技术结合的解决方案,设计了物方视场角8°×8°、入瞳口径265 mm、工作温度200 K的像方远心折射式光学系统。镜头最大口径280 mm,采用多级分散的弹性支撑设计,解决大口径低温透镜装框、透镜组件支撑和镜头整体安装各环节的热应力卸载问题。在保证高刚度和低漏热的情况下,使低温下透镜的热应力对镜头能量集中度的影响降低到可接受范围内。镜头完成装调及室温下像质确认后,进行了力学振动试验,并将其制冷到200 K水平测试像质,测试结果表明,镜头能量集中度达到轴上75%,边缘视场72%。     

Decorating surface charge of graphite nanoplate using an electrostatic coupling agent for 3-dimensional polymer nanocomposite

Here, we report a facile approach to electrostatically couple the surface charges of graphite nanoplate (GNP) fillers and poly(methyl methacrylate) (PMMA) polymer particles using ethylene maleic anhydride (EMA) copolymer as an electrostatic coupling agent. Our strategy involved switching the intrinsic repulsive electrostatic interactions between the directly exfoliated GNPs fillers and the PMMA particles to attractive electrostatic surface interactions for preparing core(PMMA)-shell (GNP) precursor in order to optimizing 3-dimensionally dispersed polymer nanocomposite. As a result, the electrical conductivity of the composites dramatically increased by a factor of 16.7 in the EMA-coupled GNP/PMMA composites compared with that of the EMA-free GNP/PMMA composites. In addition, the percolation threshold was also notably reduced from 0.32 to 0.159 vol% after electrostatic coupling of the GNPs fillers and PMMA particles. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48390.     

芦岭煤矿塌陷区土壤重金属污染特征研究

安徽皖北地区作为我国重要的煤炭工业基地,煤炭的大量开采不仅造成了地表塌陷、大气污染、水污染等,还对所在区域的土壤造成了污染。选择宿州东南典型的采煤塌陷区——芦岭煤矿塌陷区,采用野外调查与室内实验分析相结合的方法,对芦岭塌陷区土壤重金属Cr、Cu、Zn、Co、Pb、Ni的污染状况进行了分析,以了解皖北地区采煤塌陷区土壤的重金属污染情况,找出其中主要的污染元素,为当地的环境修复提供了科学依据。     

Synthesis and properties of (Hf1-xTax)C solid solution carbides

Thermodynamically stable (Hf_1–xTa_x)C (x?=?0.1–0.3) compositions were selected by First Principle Calculation and synthesized in nanopowders via high-energy ball milling and carbothermal reduction of commercial oxides at 1450?°C. The formation of a solid solution during powder synthesis was investigated. The solid solution carbide powders were sintered at 1900?°C by spark plasma sintering without a sintering aid. As a result, the (Hf_1–xTa_x)C solid solution carbides exhibited high densities, excellent hardness and fracture toughness (ρ: 98.7–100.0%, HVN: 19.69–19.98?GPa, K_IC: 5.09–5.15?MPa?m^1/2) compared with previously reported HfC and HfC–TaC solid solution carbides.     

Growth,microstructure, energy–storage and dielectric performances of chemical–solution NBT–based thin films: Effect of sodium nonstoichimometry

Na_0.5+δBi_0.5(Ti_0.96W_0.01Ni_0.03)O₃ thin films with various Na contents (abbreviated as Na_.5+δBTWN, δ?=?? 3.0, ??1.5, 0, 1.5%) were fabricated on ITO/glass substrates using a chemical–solution process. The effects of Na nonstoichiometry on the microstructure, insulating, ferroelectric and dielectric performances are investigated. The pure perovskite phase can be obtained in Na_0.5BTWN and Na_0.515BTWN, while for Na_0.470BTWN or Na_0.485BTWN, the main composition contains secondary phase of TiO₂. The grain size increases from 30?nm at δ?=?? 3.0% to 55?nm at δ?=?0%, then decreases to 52?nm with δ?=?1.5%. The leakage current of Na_0.485BTWN sample is reduced dramatically in comparison with Na_0.5+δBTWN (δ?=?? 3.0, 0, 1.5%). The big recoverable energy–storage density of 63.1?J/cm² and high energy–storage efficiency of 55.0% can be obtained for Na_0.485BTWN due to the improved electric break–down strength and large difference value between the remanent polarization and maximum polarization. Enhanced dielectricity is achieved in Na_0.485BTWN with a high tunability of 36.0% and a figure of merit of 4.0 at 450?kV/cm and 500?kHz. These results demonstrated that the crystallization, micrographs and energy storage and dielectric properties of Na_0.5Bi_0.5TiO₃ are highly sensitive to low levels of Na–site nonstoichiometry.