Influence of Al Addition on the Microstructure and Mechanical Properties of Mg-Zn-Sn-Mn-Ca Alloys.

The effects of Al addition on the microstructure and mechanical properties of Mg-Zn-Sn-Mn-Ca alloys are studied in this paper. It was found that the Mg-6Sn-4Zn-1Mn-0.2Ca-xAl (ZTM641-0.2Ca-xAl, x = 0, 0.5, 1, 2 wt.%; hereafter, all compositions are in weight percent unless stated otherwise) alloys have α-Mg, Mg2Sn, Mg7Zn3, MgZn, α-Mn, CaMgSn, AlMn, Mg32(Al,Zn)49 phases. The grain is also refined when the Al element is added, and the angular-block AlMn phases are formed in the alloys. For the ZTM641-0.2Ca-xAl alloy, the higher Al content is beneficial to elongation, and the double-aged ZTM641-0.2Ca-2Al alloy has the highest elongation, which is 13.2%. The higher Al content enhances the high-temperature strength for the as-extruded ZTM641-0.2Ca alloy; overall, the as-extruded ZTM641-0.2Ca-2Al alloy has the best performance; that is, the tensile strength and yield strength of the ZTM641-0.2Ca-2Al alloy are 159 MPa and 132 MPa at 150 °C, and 103 MPa and 90 MPa at 200 °C, respectively.

Characteristics and phylogenetic analysis of the complete mitochondrial genome of Glyptothorax pallozonus (Siluriformes, Sisoridae).

Glyptothorax pallozonus Lin, 1934 is a small benthic fish belonging to the Sisoridae family that is distributed in the Dongjiang and Rongjiang Rivers of China. In the present study, we sequenced and characterized the complete mitochondrial genome of G. pallozonus for the first time. The complete mitogenome of G. pallozonus is 16,542 bp in length and includes 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), two ribosomal RNA (rRNAs), and a control region (CR). The mitogenome architecture was identical to that of other teleosts. Maximum likelihood (ML) phylogenetic analysis strongly supported the monophyly of Glyptothorax, which contains two clades. These results advance our understanding of the molecular phylogeny of the genus Glyptothorax.

Efficient visible-light-driven S-scheme AgVO3/Ag2S heterojunction photocatalyst for boosting degradation of organic pollutants.

The traditional semiconductor photocatalysts for solving the related environmental aggravation are often challenged by the recombination of photogenerated carriers. Designing an S-scheme heterojunction photocatalyst is one of the keys to tackling its practical application problems. This paper reports an S-scheme AgVO3/Ag2S heterojunction photocatalyst constructed via a straightforward hydrothermal approach that exhibits outstanding photocatalytic degradation performances to the organic dye Rhodamine B (RhB) and antibiotic Tetracycline hydrochloride (TC-HCl) driven by visible light. The results show that AgVO3/Ag2S heterojunction with a molar ratio of 6:1 (V6S) possesses the highest photocatalytic performances, 99% of RhB can be almost degraded by 0.1 g/L V6S within 25 min light illumination, and about 72% of TC-HCl can be photodegraded with the act of 0.3 g/L V6S under 120 min light irradiation. Meanwhile, the AgVO3/Ag2S system exhibits superior stability and maintains high photocatalytic activity after 5 repeated tests. Moreover, the EPR measurement and radical capture test identify that superoxide radicals and hydroxyl radicals mainly contribute to the photodegradation process. The present work demonstrates that constructing an S-scheme heterojunction can effectively inhibit the recombination of carriers, providing insights into the fabrication of applied photocatalysts for practical wastewater purification treatment.

Preparation of poly(ionic liquid)/multi-walled carbon nanotube fillers using divinylbenzene as a linker to enhance the impact resistance of polyurethane elastomers.

The brittle fracture of polyurethane elastomer (PUE) under high-speed impact limits its application in high-speed impact protection. Here, based on the principle of free radical polymerization and π-π conjugation, composite nanoparticles (C-MWCNTs) are prepared by copolymerization of epoxy group ionic liquid (GVIMBr) and divinylbenzene (DVB) on MWCNTs using DVB as a linker. C-MWCNTs participate in the curing process of PUE through epoxy groups to form in situ crosslinked C-MWCNTs/PUE, which improves the energy absorption and high-speed impact properties of PUE. Compared with neat PUE, the maximum compressive strength and energy absorbed by C-MWCNTs/PUE are increased by 46.3% and 23.6%, respectively. By observing the microsurface and fracture morphology of C-MWCNTs/PUE, the relationship between macroscopic mechanical properties and microstructure is constructed. The improvement of the mechanical properties of the C-MWCNTs/PUE is attributed to the interfacial interaction and homogeneous dispersion of the C-MWCNTs in the PUE matrix. These microscopic effects are caused by the good compatibility between GVIMBr and PUE matrix and the synergistic enhancement between GVIMBr and MWCNTs.

Study on Mechanical Properties and High-Speed Impact Resistance of Carbon Nanofibers/Polyurethane Composites Modified by Polydopamine.

Polyurethane elastomers (PUE), with superior mechanical properties and excellent corrosion resistance, are applied widely to the protective capability of structures under low-speed impact. However, they are prone to instantaneous phase transition, irreversible deformation and rupture even arising from holes under high-speed impact. In this paper, mussel adhesion proteins were applied to modify carbon nanofibers (CNFs) in a non-covalent way, and creatively mixed with PUE. This can improve the dispersity and interfacial compatibility of nanofillers in the PUE matrix. In addition, the homogeneous dispersion of modified nanofillers can serve as "reinforcing steel bars". The nanofillers and PUE matrix can form "mud and brick" structures, which show superb mechanical properties and impact resistance. Specifically, the reinforcement of 1.0 wt.% modified fillers in PUE is 103.51%, 95.12% and 119.85% higher than the neat PUE in compression modulus, storage modulus and energy absorption capability, respectively. The results have great implications in the design of composite parts for aerospace and army vehicles under extreme circumstances.

Study on Bone-like Microstructure Design of Carbon Nanofibers/Polyurethane Composites with Excellent Impact Resistance.

It is a challenge to develop cost-effective strategy and design specific microstructures for fabricating polymer-based impact-resistance materials. Human shin bones require impact resistance and energy absorption mechanisms in the case of rapid movement. The shin bones are exciting biological materials that contain concentric circle structures called Haversian structures, which are made up of nanofibrils and collagen. The "soft and hard" structures are beneficial for dynamic impact resistance. Inspired by the excellent impact resistance of human shin bones, we prepared a sort of polyurethane elastomers (PUE) composites incorporated with rigid carbon nanofibers (CNFs) modified by elastic mussel adhesion proteins. CNFs and mussel adhesion proteins formed bone-like microstructures, where the rigid CNFs are served as the bone fibrils, and the flexible mussel adhesion proteins are regarded as collagen. The special structures, which are combined of hard and soft, have a positive dispersion and compatibility in PUE matrix, which can prevent cracks propagation by bridging effect or inducing the crack deflection. These PUE composites showed up to 112.26% higher impact absorbed energy and 198.43% greater dynamic impact strength when compared with the neat PUE. These findings have great implications for the design of composite parts for aerospace, army vehicles, and human protection.

A Micro-Nano Structure Formed by SiC/Graphene Oxide Self-Assembly Improves the Wear Resistance and Corrosion Resistance of an Epoxy-Based Composite Coating.

In air and railway transportation, corrosion and wear lead to the rapid failure of equipment. Epoxy (EP)-based coatings are widely used in research on the anti-corrosion of organic coatings, but their application as materials for wear resistance is limited due to their non-abrasive properties. In this study, a novel high-performance epoxy-based composite coating was developed through the self-assembly of silicon carbide (SiC) and graphene oxide (GO) and the tuning of the interfacial structure with epoxy resin. The coatings were comprehensively characterized, including their electrochemical behavior, a salt spray test, and friction and wear experiments, and the optimal addition ratio of SiC-G@GO (SiC-G@GO was prepared by the self-assembly of γ-(2,3-epoxypropoxy) propytrimethoxysilane (KH560)-modified SiC (SiC-G) on the surface of GO sheets) in the epoxy coatings was explored. Benefiting from the labyrinth effect and their rolling-friction-like microstructure, the 1 wt% SiC-G@GO/EP coating exhibits excellent wear and corrosion resistance. Compared with pure epoxy resin, the 1 wt% SiC-G@GO/EP coating increased by 4 orders of magnitude after 10 days of immersion. The average friction coefficient was 41.5% lower than that of the pure EP coating, and the wear rate was 56.6% lower. This research has positive implications for the development and application of anti-corrosion and wear-resistant organic coatings.

Microstructure and Mechanical Properties of As-Aged Mg-Zn-Sn-Mn-Al Alloys.

The microstructure and mechanical properties of as-aged Mg-6Zn-4Sn-1Mn-xAl (ZTM641-xAl, x = 0, 0.2, 0.5, 1, 2, 3 and 4 wt.%) alloys are studied in this paper. In terms of microstructure, the results reveal that the addition of Al mainly leads to the formation of the Al8Mn5, Al11Mn4, Al2Mg5Zn2 and Mg32(Al,Zn)49 phases. With increases in the addition of Al, the average grain size first decreases and then increases, while the undissolved phases increase. The average grain size of the ZTM641-0.5Al alloy is the smallest, and the single-aged and double-aged grain size is 14 µm and 12 µm, respectively. As for mechanical properties, with increases in the Al element, the strength decreases, and the elongation first increases and then decreases. The double-aged ZTM641-0.2Al alloy exhibits favorable mechanical properties at room temperature, and the UTS, YS and elongation are 384 MPa, 360 MPa and 9%, respectively. Further, the double-aged ZTM641-0.2Al alloy exhibits the comprehensive mechanical properties at 150 °C, that is, the UTS, YS and elongation are 212 MPa, 196 MPa and 29%, respectively, which is about 45% higher than that of the elongation of ZTM641. The ZTM641-xAl alloys exhibits mixed fracture at room temperature, and, with increases in the addition of Al, the fracture mechanisms of alloys are mixed fracture, ductile fracture and mixed fracture at 200 °C.

In Situ Grafted Composite Nanoparticles-Reinforced Polyurethane Elastomer Composites with Excellent Continuous Anti-Impact Performance.

Polyurethane elastomer (PUE) has attracted much attention in impact energy absorption due to its impressive toughness and easy processability. However, the lack of continuous impact resistance limits its wider application. Here, an amino-siloxane (APTES) grafted WS2-coated MWCNTs (A-WS2@MWCNTs) filler was synthesized, and A-WS2@MWCNTs/PUE was prepared by using the filler. Mechanical tests and impact damage characterization of pure PUE and composite PUE were carried out systematically. Compared with pure PUE, the static compressive strength and dynamic yield stress of A-WS2@MWCNTs/PUE are increased by 144.2% and 331.7%, respectively. A-WS2@MWCNTs/PUE remains intact after 10 consecutive impacts, while the pure PUE appears serious damage after only a one-time impact. The improvement of mechanical properties of A-WS2@MWCNTs/PUE lies in the interfacial interaction and synergy of composite fillers. Microscopic morphology observation and damage analysis show that the composite nanofiller has suitable interfacial compatibility with the PUE matrix and can inhibit crack growth and expansion. Therefore, this experiment provides an experimental and theoretical basis for the preparation of PUE with excellent impact resistance, which will help PUE to be more widely used in the protection field.

Effects of Modified Al2O3-Decorated Ionic Liquid on the Mechanical Properties and Impact Resistance of a Polyurethane Elastomer.

In this work, a new composite material with excellent dynamic impact resistance and outstanding quasi-static mechanical properties was synthesized. The composite material is composed of a polyurethane elastomer and a novel nano-polymer. The nano-polymer was composed of silane coupling agent-modified alumina microspheres and functionalized ionic liquids by double bond polymerization. The universal testing machine and split Hopkinson pressure bar were used to characterize the compression behavior, strength and energy absorption of the composite materials under static and dynamic conditions. Additionally, the comprehensive mechanical properties of polyurethane elastomer with different nano-polymer loadings (0.5-2.5 wt.%) were studied. The results show that whether it was static compression or dynamic impact, the polyurethane elastomer with 1% nano-polymer had the best performance. For the composite material with the best properties, its compressive yield strength under the static compression was about 61.13% higher than that of the pure polyurethane elastomer, and its energy absorption of dynamic impacts was also increased by about 15.53%. Moreover, the shape memory effect was very good (shape recovery is approximately 95%), and the microscopic damage degree was relatively small. This shows that the composite material with the best properties can withstand high compression loads and high-speed impacts. The developed composite material is a promising one for materials science and engineering, especially for protection against compression and impacts.

Effect of Rapid Cold Stamping on the Evolution of Long Strip-Shaped Nanoprecipitation in Al-Cu-Mg Alloy.

High-resolution transmission electron microscopy (HRTEM), X-ray diffractometry (XRD), energy dispersive spectroscopy (EDS), and hardness testing are used to investigate the evolution of the long strip-shaped S' phase of spray-formed fine-grained Al-Cu-Mg alloy during rapid cold stamping deformation. The elongated S' phase of the extruded Al-Cu-Mg alloy is subjected to twisting, brittle fracturing, redissolution, and necking during rapid cold stamping deformation. As a result, the morphology, size, distribution, and orientation relationship with the matrix of the long strip-shaped S' phase changed significantly. The regularly distributed long strip-shaped nanoscale precipitates evolved into irregularly distributed short rod-shaped S' phases and diffusely distributed granular reprecipitates. The twist and brittle fracture of the long strip-shaped S' phase significantly increased the contact surface between the precipitated phase and the aluminum matrix, improved the interfacial distortion energy of the precipitated phase and the aluminum matrix, and promoted the redissolution of the S' phase. The supersaturation state is reached, thus resulting in reprecipitation, which then lowered the matrix free energy. The hardness of the extruded Al-Cu-Mg alloy increased from 54.2 HB to 128.1 HB during the rapid cold stamping process.

Effect of Y Addition on the Microstructure and Mechanical Properties of ZM31 Alloy.

Effects of different Y contents (0, 0.3, 0.7, 1.5, 3, 5 and 10 wt.%) on the microstructure, thermal stability and mechanical properties of Mg-3Zn-1Mn (ZM31) alloys were systematically studied. The existence form and action mechanism of Y in the experimental alloys were investigated. The results revealed that with the change of Y content, the main phases of the ZM31-xY alloys changed from Mg7Zn3 phase, I-phase, I + W-phase, W-phase, W + LPSO phase to LPSO phase. When Y content was low (≤1.5%), hot extrusion could break up the residual phases after homogenization to form dispersed fine rare-earth phase particles, and fine second phases would also precipitate in the grain, which could inhibit the grain growth. When Y content was high (≥3%), the experimental alloys were only suitable for high-temperature extrusion due to the formation of the high heat stable rare-earth LPSO phase. In addition, Y could evidently enhance the mechanical properties of the as-extruded ZM31 alloy, of which the ZM31-10Y alloy had the best mechanical properties, that is, the tensile and yield strengths are 403 MPa and 342 MPa. The high strengths of the alloys were mainly determined by fine grain strengthening, rare-earth phase strengthening and dispersion strengthening of fine α-Mn particles.

Effect of Ti Transition Layer Thickness on the Structure, Mechanical and Adhesion Properties of Ti-DLC Coatings on Aluminum Alloys.

Multilayers of Ti doped diamond-like carbon (Ti-DLC) coatings were deposited on aluminum alloys by filtered cathodic vacuum arc (FCVA) technology using C2H2 as a reactive gas. The effect of different Ti transition layer thicknesses on the structure, mechanical and adhesion properties of the coatings, was investigated by scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), nanoindentation and a scratch tester. The results showed that the Ti transition layer could improve interfacial transition between the coating and the substrate, which was beneficial in obtaining excellent adhesion of the coatings. The Ti transition layer thickness had no significant influence on the composition and structure of the coatings, whereas it affected the distortion of the sp²-C bond angle and length. Nanoindentation and scratch test results indicated that the mechanical and adhesion properties of the Ti-DLC coatings depended on the Ti transition layer thickness. The Ti transition layer proved favorable in decreasing the residual compressive stress of the coating. As the Ti transition layer thickness increased, the hardness value of the coating gradually decreased. However, its elastic modulus and adhesion exhibited an initial decrease followed by an increasing fluctuation. Among them, the Ti-DLC coating with a Ti transition layer thickness of 1.1 µm exhibited superior mechanical properties.

Flake-like InVO4 modified TiO2 nanofibers with longer carrier lifetimes for visible-light photocatalysts.

Highly efficient solar light absorption capabilities and quantum yields in photocatalysts are key to their application in photocatalytic fields. Towards this end, TiO2/InVO4 nanofibers (NFs) have been designed and fabricated successfully by a one-pot electrospinning process. The resulting TiO2/InVO4 NFs display excellent visible-light photocatalytic activity, owing to their prominent visible-light absorption and electron-hole separation properties. Time-resolved transient PL spectroscopy demonstrated that the TiO2/InVO4 NFs display longer emission decay times (22.0 ns) compared with TiO2 NFs (15.5 ns), implying that the heterojunction can remarkably suppress the electron-hole recombination and promote the carrier transfer efficiency. With tailored heterostructure features, TiO2/InVO4 NFs exhibit superior visible-light photodegradation activity, and after 80 min of visible-light irradiation, almost 95% of RhB molecules can be decomposed by TiO2/InVO4 NFs, while only 18% of RhB molecules can be decomposed by pure TiO2 NFs.

[Circular dichroism chromatography of secondary structures of anti-HBV IgY in eggs from hens immunized with recombinant yeast HBV vaccine].

OBJECTIVE: To study the generation and structure of anti-HBV IgY in eggs from hens immunized with recombinant yeast HBV vaccine. METHODS: From the hens immunized three times with the recombinant yeast HBV vaccine, the eggs were collected to extract anti-HBV IgY. After purified, the anti- HBV IgY was detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and reverse phase high-performance liquid chromatography (RP-HPLC), and its secondary structure was examined by circular dichroism (CD) chromatography. RESULTS: The relative molecular mass (Mr;) of anti-HBV IgY expressed by the recombinant yeast HBV vaccine on hens was 178 000. CD chromatography showed that the α-helix, ß-fold, ß-turn and random coil of anti-HBV IgY had 38, 0, 44 and 17 amino acids, respectively. CONCLUSION: The anti-HBV IgY can be expressed in eggs from hens immunized with recombinant yeast HBV vaccine. The α-helix and ß-turn are major secondary structures of anti-HBV IgY.