A triple-shape memory material fabricated by in situ crosslinking of poly(butylene adipate-co-terephthalate)/ε-polycaprolactone via electron-beam irradiation and its triple-shape memory effects

In this work, we fabricated a triple-shape memory polymeric material though in situ crosslinking of poly(butylene adipate-co-terephthalate)/ε-polycaprolactone blends induced by electron beam irradiation. The intrinsic property of irradiation crosslinking, crosslinking rule in this heterogeneous system, formation of interfacial bridge molecular, and the resulted interfacial strength were investigated. No obvious interfacial slips were observed in tensile test, and the elongation at break was above 900%. The high-temperature relaxation and recovery experiments at nonlinear region confirmed the excellent hyperelasticity and recovery ratios (R_r ) can be as high as 95% for samples irradiated above 96 kGy. The mismatch between heating rate and relaxation kinetics resulted in both instable temporary shapes and heating-mode dependent recovery behavior during the recovery process. Self-stability of the temporary shape at middle temperature was also emphasized in view of the phenomenon that the second R_r was above 100% in our experiments. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48588.     

石墨烯增强铜基复合材料的制备技术及发展

石墨烯由于其独特的二维结构和优异的物化性能,在改善复合材料的力学性能、电学性能和热学性能等方面具有很大的潜力,已成为金属基复合材料较理想的增强体。铜合金具有优异的导电导热性能和良好的延展性,但是其强度较低、不耐磨及高温下易变形的特点阻碍了其应用和发展。因此,结合石墨烯和铜的性能特点,将石墨烯作为增强体添加到铜中,制备性能优异的石墨烯增强铜基复合材料成为目前研究的热点之一。综述了目前石墨烯增强铜基复合材料的制备方法,并对各方法的特点进行了分析比较,提出未来可采用的制备工艺的方向以及在制备过程中面临的问题和挑战,并对其未来的研究方向进行了展望。     

Synthesis of a novel char-forming agent (PEIC): Improvement in flame retardancy,thermal stability,and smoke suppression for intumescent flame-retardant polypropylene composites

A novel char-forming agent named PEIC was designed and synthesized combining pentaerythritol octahydrogen tetraphosphate (PEPA) and tris(2-hydroxyethyl) isocyanurate. PEIC was combined with the silica-gel-microencapsulated ammonium polyphosphate (OS-MCAPP), preparing intumescent flame-retardant polypropylene (PP) composites. The results of the limiting oxygen index (LOI) show that the composite containing 30 wt % IFR with OS-MCAPP:PEIC = 2:1 presents the optimal LOI of 32.7%. Meanwhile, the cone calorimeter tests show that its peak heat release rate is 432 kW m⁻², which decreases by 62.1% compared with that of pure PP, showing a high-efficient flame retardancy. The exhibited UL-94 V-0 rating for all the composites indicates that the IFR composed of PEIC and OS-MCAPP has high-efficient flame retardancy in PP. The analysis of residue char reveals that PEIC could improve the quality of char in compactness, intumescentia, and the degree of graphitization. Further, the effect of IFR on the mechanical properties of PP composites was also evaluated and discussed. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48296.     

Highly efficient synthesis of(R)-1,3-butanediol via anti-Prelog reduction of 4-hydroxy-2-butanone with absolute stereoselectivity by a newly isolated Pichia kudriavzevii

(R)-1,3-butanediol is an important pharmaceutical intermediate, and the synthesis of(R)-1,3-butanediol using green biological methods has recently been of interest for industrial application. Here, a novel strain QC-1 that efficiently transforms 4-hydroxy-2-butanone to(R)-1,3-butanediol was isolated from soil samples. Based on morphological, physiological, and biochemical tests and 5.8 S-internal transcribed spacer sequencing, the strain was identified as Pichia kudriavzevii QC-1. The reaction conditions were optimized to 35 ℃, pH 8.0, rotation speed 200 rpm, and 6:5 mass ratio of glucose to 4-hydroxy-2-butanone. Evaluation of the effects of 4-hydroxy-2-butanone concentrations on yield and cell survival rate showed that 85.60 g·L~(-1) product accumulated, with an enantiomeric excess of more than 99%, when 30 g·L~(-1)4-hydroxy-2-butanone was added at 0, 10, and 30 h in a 3-L bioreactor. Thus, strain QC-1 showed excellent catalytic activity and stereoselectivity for the synthesis of(R)-1,3-butanediol from 4-hydroxy-2-butanone.     

Li-doping stabilized P2-Li0.2Na1.0Mn0.8O2 sodium ion cathode with oxygen redox activity

The discovery of the oxygen chemistry phenomenon reveals bright future toward new sustainable layered Na-based transitional oxides. However, the poor capacity retention problem of the cathode has hindered the development of sodium ion batteries (SIBs). In this work, a new Li-doped compound Li_0.2Na_1.0Mn_0.8O₂ is proposed, which demonstrates refined cycling durability with 51.6% after 100 cycles at 50 mA g⁻¹, superior than Na_1.2Mn_0.8O₂ with only one cycle. Then in situ X-ray diffraction (XRD) and density function theory (DFT) are employed to explore the lattice distortion and confirm stable lattice framework introduced by Li atoms with eliminated P2-O2 phase transition upon cycling, guaranteeing outstanding electrochemically stable performance. In addition, Li_0.2Na_1.0Mn_0.8O₂ demonstrates activation of Mn as well as O chemistry redox in the lattice, detected by ex situ electronic paramagnetic resonance spectroscopy (EPR) as well as in situ Raman, which indicate not only Na-deficient Mn-based layered oxide but also Na-rich Mn-based compound can represent oxygen redox.     

夏邑县火店南煤勘查区二2煤层煤质评价

夏邑县火店南煤勘查区位于夏邑县城东南25 km。通过对主要可采煤层二₂煤各指标的定量分析表明，勘查区二₂煤属半亮型煤，低灰、低挥发分、特低硫、较高软化温度灰和较高流动温度灰、特高热值的无烟煤三号和贫煤。贫煤可作气化、动力和民用煤；无烟煤除可作动力和民用外，块煤可作化工原料，经过一定加工，粉状煤可供高炉喷吹燃料。     

Photoelectrocatalytic Reduction of CO<Subscript>2</Subscript> to Chemicals via ZnO@Nickel Foam: Controlling C–C Coupling by Ligand or Morphology

The CO₂ reduction is a very attracting research field in the environmental, material and chemical sciences in light of the energy crisis and greenhouse effect. A new photoelectrocatalytic system composed of a photoanode BiVO₄ and a photocathode of nickel foam supported ZnO semiconductor was designed, assembled and applied to CO₂ reduction in water. The photocathodes with different morphology could be made from electrochemical deposition method and well characterized by SEM, UV–Vis, XRD, and XPS. The photoelectrocatalytic cell of ZnO/Ni-30|KHCO₃|BiVO₄ can produce ethanol and acetic acid in a rate of 12.5 µM h^?1 cm^?2 with 100% selectivity for C₂ product, attributing to the controlling of 3D-spaces of nanorod. The cell of A-ZnO/Ni-15|KHCO₃|BiVO₄ produces ethanol and acetic acid with 75% selectivity for C₂ product under 100 mW cm^?2 simulated sunlight irradiation, attributing to controlling of both amine ligand and morphology of ZnO, which reveal a new way to increase the selectivity of products.     

Heat-treatable Mg-9Al-6Sn-3Zn extrusion alloy

Mg-9Al-6Sn-3Zn (wt%) alloy was extruded and heat treated in T5 and T6 conditions, and its mechanical properties and microstructures were investigated. The extruded product can be slightly strengthened by the T5 treatment as a result of sparse and heterogeneous precipitation. Significant increase in strength is achieved by the T6 treatment, and this is mostly attributed to the formation of lamellar discontinuous Mg₁₇Al₁₂ precipitates. The segregation of Al and Zn at grain boundaries is responsible for the discontinuous Mg₁₇Al₁₂ nucleation. The T6-treated alloy exhibits a tensile yield strength of 341 MPa and an ultimate tensile strength of 409 MPa, together with an elongation to fracture of 4%.     

快速凝固高硅铝合金加热过程中的组织转变

利用气雾化法制备高硅铝合金粉末,采用光学显微镜(OM)、扫描电镜(SEM)等现代测试手段,分析快速凝固高硅铝合金不同粒度粉末微观组织和结构特征,研究在不同加热温度和保温时间条件下针状富铁相的转变特性及β-Si相的粗化行为。结果表明:快速凝固高硅铝合金组织主要以基体上分布有大量细小的颗粒状和针状相为特征,合金粉末在加热过程中,随着温度的升高和保温时间的延长,颗粒β-Si相有粗化趋势,针状非平衡富铁相转变为棒状或颗粒状平衡相。通过台阶式连续加热模拟试验可获得针状相基本消失且颗粒β-Si相未发生明显粗化的组织。     

Improved Stable Indocyanine Green (ICG)‐Mediated Cancer Optotheranostics with Naturalized Hepatitis B Core Particles

In recent years, hepatitis B core protein virus‐like particle (HBc VLP) is an impressive biomaterial, which has attracted considerable attention due to favorable properties such as structural stability, high uptake efficiency, and biocompatibility in biomedical applications. Heretofore, only a few attempts have been made to apply it in physical, chemical, and biological therapy for cancer. In this study, a tumor‐targeting RGD‐HBc VLP is first fabricated through genetic engineering. For image‐guided cancer phototherapy, indocyanine green (ICG) is loaded into RGD‐HBc VLP via a disassembly/reassembly pathway and electrostatic attraction with high efficiency. The self‐assembled stable RGD‐HBc VLP significantly improves body retention (fourfold longer), aqueous stability, and target specificity of ICG. Remarkably, these positive reformations promote more accurate and sensitive imaging of U87MG tumor, as well as prolonged tumor destruction in comparison with free ICG. Moreover, the photothermal and photodynamic effect on tumors are quantitatively differentiated by multiple linear regression analysis. Overall, less‐potent medicinal ICG can be perfectly rescued by bioengineered HBc VLP to realize enhanced cancer optotheranostics.