Thermal annealing effects on the energy storage properties of BST ceramics

Thermal annealing treatments with different atmospheres (air, oxygen, and reducing atmospheres, respectively) were employed for the conventionally sintered (Ba_0.4Sr_0.6)TiO₃ (BST) ceramics. The effect of thermal annealing on the energy storage properties of BST ceramics was investigated, where oxygen vacancies played an important role. The dielectric loss, bulk resistivity and dielectric breakdown strength (BDS) were found to be sensitive to the annealing process, leading to the different energy densities in the range of 0.30‐0.80 J/cm³. Temperature‐dependent dielectric measurement and thermally stimulated depolarization current analysis were conducted to understand the impacts of oxygen vacancies on the macroscopic properties, which were found to be closely associated with the annealing conditions.     

Zero thermal expansion in cubic MgZrF6

Isotropic zero thermal expansion (ZTE) is rare but intriguing physical property in materials. Here, we report an isotropic ZTE property in a double ReO₃‐type compound of MgZrF₆, which exhibits a negligible value of coefficient of thermal expansion (α_l = ?7.94 × 10^?7 K^?1 (XRD), α_l = ?4.22 × 10^?7 K^?1 (dilatometry), 300‐675 K). The ZTE mechanism of MgZrF₆ is understood by the joint studies of temperature dependence of crystal structure and lattice dynamics. Interestingly, different magnitudes of atomic displacement parameters (ADPs) for the fluorine atoms in MZrF₆ (M = Ca, Ni, Mg) are found. The strong temperature sensitivity of ADPs demonstrates intensive transverse thermal vibration of fluorine atoms, which contributes essentially to the negative thermal expansion of CaZrF₆. By contrast, for NiZrF₆ with positive thermal expansion, the temperature response of ADPs is weak. Moderate transverse thermal vibration takes place in MgZrF₆, and ZTE appears. Furthermore, lattice dynamics of MgZrF₆ is studied by temperature‐dependent Raman spectroscopy, which reveals the ZTE mechanism. In particular, the F_2g and A_g modes, corresponding to the bending and stretching vibrations of fluorine atoms, respectively, neither soften nor harden over the whole temperature range, which is correlated with the isotropic ZTE property of MgZrF₆.     

Numerical investigation of three-dimensional fiber suspension flow by using finite volume method

Fiber suspension flow is common in many industrial processes like papermaking and fiber-reinforcing polymer-based material forming. The investigation of the mechanism of fiber suspension flow is of significant importance, since the orientation distribution of fibers directly influences the mechanical and physical properties of the final products. A numerical methodology based on the finite volume method is presented in the study to simulate three-dimensional fiber suspension flow within complex flow field. The evolution of fiber orientation is described using different formulations including FT model and RSC model. The pressure implicit with splitting of operators algorithm is adopted to avoid oscillations in the calculation. A laminate structure of fiber orientation including the shell layer, the transition layer and the core layer along radial direction within a center-gated disk flow channel is predicted through a three-dimensional simulation, which agrees well with Mazahir’s experimental results. The evolution of fiber orientation during the filling process within the complex flow field is further discussed. The mathematical model and numerical method proposed in the study can be successfully adopted to predict fiber suspension flow patterns and hence to reveal the fiber orientation mechanism.     

Determination of Organophosphorus Pesticides in Edible Oils by Dispersive Microextraction Based on Acetonitrile/Water-coated Fe3O4

In the present work, a novel dispersive microextraction technique based on acetonitrile/water-coated Fe₃O₄ was proposed to determine the organophosphorus pesticides (OPP) including phorate, diazinon, chlorpyrifos-methyl, pirimiphos-methyl and chlorpyrifos in edible oils. In the method, acetonitrile coated bare Fe₃O₄ was used as the extractant, Fe₃O₄ served as the supporter of acetonitrile, a trace amount of water acted as a crosslinking agent between acetonitrile and bare Fe₃O₄. The analytes adsorbed A/W-Fe₃O₄ can be easily collected and isolated from the sample solution using a magnet before gas chromatography-mass spectrometry (GC–MS) analysis. Several dominant parameters affecting extraction efficiency were investigated and optimized. Under the optimal conditions, the limits of detection and limits of quantification for the five OPP were 1.1–6.7 and 4.8–18.3 ng/g, respectively. The recoveries in spiked real oil samples were in the range of 63.8–102.7 % with RSD between 4.9 and 14.3 %. The proposed simple, rapid and solvent-saving method was successfully applied to detect OPP in edible oils.     

Effect of Vacuum-Microwave Predrying on Quality of Vacuum-Fried Potato Chips

The effects of vacuum microwave predrying on the quality of vacuum-fried potato chips were studied. The results showed that vacuum microwave predrying had a significant effect on moisture and oil contents, as well as color parameters and structure of potato chips. Vacuum microwave predrying significantly decreased the oil and moisture contents of vacuum-fried potato chips. The rates of both mass transfer phenomena (water loss and oil uptake) that take place during the vacuum frying of potato chips decrease due to the vacuum microwave predrying. The vacuum microwave predrying had a negative effect on color of potato chips, which decreases the L value of potato chips and increases Hunter a and b values. Breaking force of fried potato chips is also significantly (P < 0.05) affected by the drying pretreatment, which decreases the breaking force at the beginning of predrying and then increases with vacuum microwave predrying time.     

A Unique Approach to Characterization of Sol‐Gel‐Derived Rare‐Earth‐Doped Oxyfluoride Glass‐Ceramics

Using the sol‐gel route Nd³⁺‐doped oxyfluoride glass‐ceramics were prepared. LiYF₄ and YF₃ crystals were deposited in the glass‐ceramics and their size, distribution, and amount ratio were varied by changing the compositions and heating temperatures. The incorporation of Nd³⁺ ions into both the fluoride crystals was confirmed by the high‐resolution elemental mapping of the glass‐ceramics. The incorporated Nd³⁺ ions showed up and down conversion photoluminescence whose properties were obviously different among the samples. The preliminary site analysis for Nd³⁺ ions was carried out using a unique approach associated with the Prony series approximation. Finally, the approach was found to be useful for the analysis of materials that are structurally complicating.     

Synthesis and Biological Evaluation of N‐Substituted Sophocarpinic Acid Derivatives as Coxsackievirus B3 Inhibitors

A series of novel N‐substituted sophocarpinic acid derivatives was designed, synthesized, and evaluated for their anti‐enteroviral activities against coxsackievirus type B3 (CVB3) and coxsackievirus type B6 (CVB6) in Vero cells. Structure–activity relationship analysis revealed that the introduction of a benzenesulfonyl moiety on the 12‐nitrogen atom in (E)‐β,γ‐sophocarpinic acid might significantly enhance anti‐CVB3 activity. Among the derivatives, (E)‐12‐N‐(m‐cyanobenzenesulfonyl)‐β,γ‐sophocarpinic acid ( 11 m ), possessing a meta‐cyanobenzenesulfonyl group, exhibited potent activity against CVB3 with a selectivity index (SI) of 107. Furthermore, compound 11 m also showed a good oral pharmacokinetic profile, with an AUC value of 7.29 μM h^?1 in rats, and good safety through the oral route in mice, with an LD₅₀ value of >1000 mg kg^?1; these values suggest a druggable characteristic. Therefore, compound 11 m was selected for further investigation as a promising CVB3 inhibitor. We consider (E)‐β,γ‐N‐(benzenesulfonyl)sophocarpinic acids to be a novel class of anti‐CVB3 agents.     

Effects of Charring Agents on the Thermal and Flammability Properties of Intumescent Flame-Retardant HDPE-based Clay Nanocomposites

Intumescent flame-retardant (IFR) high-density polyethylene, poly[ethylene-co-(vinyl acetate)], and organically-modified clay nanocomposites consisting of ammonium polyphosphate (APP) and other charring agents, as well as the nanocomposites pentaerythritol (PER), polyamide-6 (PA), and PA/OMT were investigated. Their thermal and flammability properties have been characterized by thermogravimetric analyses, cone calorimetry, a limiting oxygen index, and the UL-94 test. Results show that the PER-contained sample exhibits different thermal and flammability behaviors from the samples containing polymer charring agents. The difference is postulated to be responsible for the formation of various intumescent structures and their changes in response to heightened temperatures.     

Influence of Maleic Anhydride Grafted Ethylene-Vinyl Acetate Copolymer as a Compatibilizer on Combustion and Thermal Stability Properties of Magnesium Hydroxide Flame-Retardant Ethylene Propylene Diene Terpolymer Composites

New halogen-free, flame-retardant ethylene propylene diene terpolymer (EPDM)/organically modified magnesium hydroxide (MH) composites have been prepared via melt compounding method, using maleic anhydride grafted ethylene-vinyl acetate copolymer (MAH-g-EVA) as a compatibilizer. Influence of MAH-g-EVA on the fire and thermal properties of the composites are investigated by means of LOI, UL94 vertical burning, cone calorimeter tests, thermogravimetric analysis (TGA), real time fourier-transform infrared spectroscopy (RTFTIR) and environmental scanning electron microscopy (ESEM). The results show that MAH-g-EVA plays a positive role in improving the flame retardancy and thermal stability of the composites.     

Synthesis and photovoltaic properties of donor–acceptor polymers incorporating a structurally-novel pyrrole-based imide-functionalized electron acceptor moiety

A structurally-novel pyrrole-based imide-functionalized electron accepting monomer unit, 4,6-dibromo-2,5-dioctylpyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione (DPPD), was prepared. The new DPPD unit was copolymerized with pyrrole-based electron rich monomers, such as thiophene-(N-alkyl)pyrrole-thiophene (TPT) and fused thiophene-(N-alkyl)pyrrole-thiophene (DTP) derivatives, to afford two new polymers, namely P(TPT-DPPD) and P(DTP-DPPD), respectively. The two polymers showed a strong absorption band at 300–600 nm and 300–650 nm, respectively, and their calculated optical band gaps were 2.09 eV and 1.89 eV, respectively. The electrochemical analysis reveals that the highest occupied molecular orbital (HOMO) energy levels of P(TPT-DPPD) and P(DTP-DPPD) were positioned at −5.55 eV and −5.24 eV, respectively, whereas their lowest unoccupied molecular orbital (LUMO) energy levels were positioned at −3.46 eV and −3.35 eV, respectively. The preliminary photovoltaic properties of the polymers, P(TPT-DPPD) and P(DTP-DPPD), were examined by fabricating polymer solar cells (PSCs) with each polymer as an electron donor and PC₇₁BM as an electron acceptor. The PSCs fabricated with the configuration of ITO/PEDOT:PSS/P(TPT-DPPD) or P(DTP-DPPD):PC₇₁BM/LiF/Al showed maximum power conversion efficiency (PCE) of 0.73% and 1.64%, respectively.