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The potential application of zinc air batteries to tackle the energy shortage and environmental crisis has proposed new requirements of bifunctional catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Utilizing the special spatial structure of zeolitic imidazolate framework-67 (ZIF-67) as an ideal research platform, the effect of a trace amount of Fe on the composition and structure of as-obtained Fe-CoNC catalysts was investigated. It was revealed that, due to the increased exposed pore structure and metal species located at the near surface, the active sites for the ORR/OER on Fe-CoNC are highly exposed, greatly boosting the activity to the reduction and evolution of oxygen in alkaline media. ZABs with Fe-CoNC have the highest maximum power density of 200 mW cm−2 when operated at current densities as high as 328 mA cm−2, better than not only Fe-free CoNC, but also precious metal-based references with the same catalyst loading. [ABSTRACT FROM AUTHOR]

The hydrophobic modification of cellulose nanofibers (CNF) was carried out via free radical polymerization using methyl methacrylate (MMA) as the monomer to improve the compatibility between CNF and poly lactic acid (PLA). Followed by the preparation of the novel nanocomposites in combination of the organic montmorillonite and the substrate. The resulting nanocomposites were then coated on paper surface using a cast‐coating process in an attempt to improve the barrier properties towards water vapor and oxygen. In addition, the composite films are prepared via a solution casting method. The water vapor transmission rate (WVTR), water vapor permeability (WVP), oxygen transmission rate (OTR), and tensile strength of the as‐prepared films were systematically measured. The corresponding results demonstrated that the WVTR, WVP and OTR decreased with the addition of a certain content of MCNF in coatings. 0.2 wt% MCNF is the optimum content, showing the best gas resistance and tensile performance. The lowest value of WVTR and WVP are 10.30 g/(m2⋯24 h) and 3306.58 g⋯μm/(m2⋯24 h) for films with 0.2 wt% MCNF added, which is 88.23% and 26.05% lower than that of PLA composite film without NFC. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystal (CNC) was prepared through the hydrolysis of concentrated sulfuric acid using commercial bagasse pulp as a raw material. The performance of the developed CNC was tested through the atomic force microscope, particle size measurement, and zeta potential analysis. The melt blending method was adopted to prepare thermoplastic polyvinyl alcohol (TPVA) and CNC‐TPVA using the glycerol (GI)‐dicondensed triethylene glycol (TEG) complex. The TPVA and CNC‐TPVA were blended with poly(butylene adipate‐coterephthalate) and polylactic acid composite material (COM) through melt extrusion granulation and blown film, and then explored the effect of CNC on the UV aging properties of materials. The complex plasticizer could effectively break the PVA hydrogen bond and reduce its melting point. It had been observed that CNC had good interface compatibility with PVA, and CNC did not affect the crystallinity of PVA, but it could weaken the hydrogen bond between GI, TEG, and PVA, thereby reduce the plasticizing effect of PVA. Compared TPVA‐COM with CNC‐TPVA‐COM, detailed information of crystallization, the thermal stability of materials and mechanical properties was presented in the UV aging process, it was found that the cross‐section of CNC‐TPVA‐COM was rough, and its unevenness formed a striped structure, and its hydrogen bond strength, diffraction peak strength and anti‐aging performance were all improved. [ABSTRACT FROM AUTHOR]

Poly(butylene adipate‐co‐terephthalate) (PBAT)/polylactic acid (PLA) composites were prepared by water‐soluble polyvinyl alcohol (PVA) and degradation‐promoting agent (DPA) which were made from acidity‐regulating KH2PO4 and halloysite by a physical layer‐by‐layer coating method. The effect of PVA and DPA on the biodegradation of PBAT/PLA composites in the cross‐sectional morphology, thermal properties, molecular structure, due to degradation was evaluated using a host of characterization methods. The results showed that PVA had a good solubilizing effect on the composite system and improved the overall compatibility. DPA had little effect on the compatibility, crystallinity, and thermal stability of the composite system, but greatly accelerated the degradation. The interior of composite material containing DPA (Com‐DPA) was shown to be severely damaged after 29 weeks of degradation, which was attributed to preferential degradation of amorphous regions of the composite by ester hydrolysis. Our results demonstrated the PVA and DPA worked synergistically to promote swelling and diffusivity of degradation products, and provided an acid environment for enhancing ester hydrolysis. This technology may have good prospects for accelerated degradation of materials in agricultural applications. [ABSTRACT FROM AUTHOR]

Mutation testing is a fault‐based technique to test the quality of test suites by inducing artificial syntactic faults or mutants in a source program. However, some mutants have the same semantics as original program and cannot be detected by any test suite input known as equivalent mutants. Equivalent mutant problem (EMP) is undecidable as it requires manual human effort to identify a mutant as equivalent or killable. The constraint‐based testing (CBT) theory suggests the use of mathematical constraints which can help reveal some equivalent mutants using mutant features. In this paper, we consider three metrics of CBT theory, ie, reachability, necessity, and sufficiency to extract feature constraints from mutant programs. Constraints are extracted using program dependency graphs. Other features such as degree of significance, semantic distance, and information entropy of mutants are also extracted to build a binary classification model. Machine learning algorithms such as Random Forest, GBT, and SVM are applied under two application scenarios (split‐project and cross‐project) on ten Java programs to predict equivalent mutants. The analysis of the study demonstrates that that the proposed techniques not only improves the efficiency of the equivalent mutant detection but also reduces the effort required to perform it with small accuracy loss. [ABSTRACT FROM AUTHOR]

ABSTRACT Acrylic resin/micro-SiO2/polymethyl urea (AC/SiO2/PMU) composites were prepared by physical blends of acrylic resin latex (AC), polymethyl urea resin (PMU), and modified SiO2. The effects of SiO2 and PMU content in the hybrid composites morphology and physical properties were investigated in detail using transmission electron microscopy (TEM), UV-Vis spectrometry (UV-Vis), scanning electron microscope (SEM), thermogravimetric analysis (TGA), and contact angle measurement. The results showed that introduction of SiO2 into AC composites could increase the viscosity which caused by gelation and agglomeration of SiO2. The TEM, SEM images, and TGA results indicated that hybrid membranes have phase separation. During the film formation process, a high number of PMU and SiO2 particles of an appropriate size were stranded on the surface of the film to form matting surface. These results highlight the sensitivity of the gloss to the polymer morphology and surface. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41707. [ABSTRACT FROM AUTHOR]

Two-dimensional vanadium pentoxide inverse opal (2D V 2 O 5 IO) architecture was fabricated by polystyrene (PS) sphere template assisted electrodeposition process. In comparison to the un-templated V 2 O 5 film, the 2D V 2 O 5 IO film exhibited a highly ordered hexagonal close-packed bowel-like array, as well as noticeable electrochromism, such as transmittance modulation up to 42.6% at 800 nm, high coloration efficiency (28.6 cm 2  · C -1 ), fast ions transfer kinetic ( t b  = 7.2 s, t c  = 2.5 s). These improvements of electrochromic performance were attributed to the ordered morphology with larger surface areas, which considerably shortened the ions diffusion paths and accelerated ions migration. An electrochromic energy storage device assembled from the 2D V 2 O 5 IO film with simultaneous electrochromic and pseudocapacitive performance could not only show transmittance modulation accompanied by multicolor variations but also powered an LCD screen and an LED bulb, demonstrating a promising potential for practical applications., (© 2021 IOP Publishing Ltd.)