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The effects of Fe, Cr and thermal exposure on the microstructure and mechanical properties of Al-Si alloy were investigated in this work. The results indicated that the main phases of the Al-Si-Cu-Ni-Mg-(0.6–0.9%) Fe (wt. %) alloy were α-Al, Si, Al5Cu2Mg8Si6, Al3CuNi, Al7Cu4Ni, Al2Cu, and AlFeSi at room temperature. The size of the AlSiFe phase increased with increasing the weight fraction of Fe. The shape of Fe-rich phase changed from rod-like to star-like, followed by long needle-like with Fe varying from 0.6% to 0.9%. The mechanical properties of the studied alloys at elevated temperatures increased with Fe. The ultimate tensile strength of the three alloys at 350 °C was 111.2 MPa, 124 MPa, and 128.7 MPa, respectively. In addition, the ductility and strength of the studied alloys at room temperature decreased with increasing the Fe, due to the large size of the hard and brittle Fe-rich phase strictly cleaved the aluminum matrix. After thermal exposure, the properties of the alloy at room temperature and elevated temperature decreased obviously at the beginning of 0.5~8 h, and then tend to be stabilized during thermal exposure at 350 °C for approximately 32~64 h. Fe-rich was a thermal stable phase at 350 °C.

Photoreduction of CO2 into valuable fuels is a clean and sustainable way to mitigate the energy crisis and environmental problems. Factors limiting the efficiency of CO2 photoreduction include narrow-band light absorption, poor charge carrier separation and transport, and sluggish activation/reaction of CO2 on the surface of photocatalyst. In recent years, defect engineering of photocatalysts emerges as an effective method to improve their efficiency in the photocatalytic conversion of CO2 into useful fuels. This review is focused on discussing how structural defects can be used to modulate the electronic structure of the photocatalysts and activate the inert CO2 molecules. Special emphasis is placed on the important impact of defects on the charge carrier dynamics of the photocatalysts. Our discussions cover a variety of defective semiconductors, including metal oxides, metal sulfides, and two dimensional materials. In addition, the challenges and prospects of defect engineering in photoreduction of CO2 are also analyzed. This review aims to provide useful information about the fundamental principles of photoreduction of CO2 and guidance on the design and preparation of defective photocatalysts.

Design and development of highly efficient photocatalytic materials are key to employ photocatalytic technology as a sound solution to energy and environment related challenges. This work aims to significantly boost photocatalytic activity through rich indium vacancies (V

A novel cage-based crystalline covalent organic framework, i.e. Cage-COF-TT (TT = triammonia–terephthalaldehyde), was prepared from a prism-like triammonia-containing molecular cage and terephthalaldehyde. Its ordered structure and porosity are expected to ensure efficient drug delivery as a potent carrier. The excellent cell viability of Cage-COF-TT was testified through MTT assays with respect to both normal mouse cells and normal human hepatocyte cells. In terms of drug delivery performance, Cage-COF-TT exhibit a high loading capacity and efficient drug release profile in a simulated body fluid environment. This work offers new insights into the design and development of a COF-based drug carrier and inspires the development of versatile tools for biomedical applications.

Photocatalytic reduction of CO2 into valuable chemicals or fuels is one of the most promising solutions to mitigate climate change. However, sound photocatalysts with sensitive responses to light, efficient enrichment and reduction of CO2 have not been well explored. Herein, we design and synthesize a porous organic polymer (POP), BTN-Re (BTN = 2,2′-bipyridine triazine network) out of two key units, i.e. Re(bpy)(CO)3Cl (bpy = 2,2′-bipyridine) and melamine. Re(bpy)(CO)3Cl offers excellent CO2 reduction ability of functional units to BTN-Re; meanwhile, the abundant Lewis base sites brought in by melamine promote capture of CO2 contributing to the reduction of CO2. Steady-state fluorescence tests confirm that integrating Re(bpy)(CO)3Cl into BTN-Re skeletons efficiently inhibits electron–hole recombination. It is evident that BTN-Re exhibits an outstanding ability to photo-reduce CO2, with an average rate of 500.7 μmol g−1 h−1 under visible light irradiation. This work provides a novel strategy for designing POP-based materials as photoreduction catalysts to reduce CO2.

A stable nanoscaled single-excitation ratiometric luminescent pH sensor (MPDB-PCN) over a broad pH range from 2.5 to 8.6 is fabricated through post-synthetic modification of PCN-224 with naphthalimide-derived molecules. Due to the rapid, sensitive and linear response to pH, MPDB-PCN is capable of detecting 3-nitropropionic acid (3-NPA), an acid neurotoxin in food safety, with a low detection limit of 15 μM in sugarcane juice.

Photoreduction of CO2 into value‐added fuels is one of the most promising strategies for tackling the energy crisis and mitigating the “greenhouse effect.” Recently, metal–organic frameworks (MOFs) have been widely investigated in the field of CO2 photoreduction owing to their high CO2 uptake and adjustable functional groups. The fundamental factors and state‐of‐the‐art advancements in MOFs for photocatalytic CO2 reduction are summarized from the critical perspectives of light absorption, carrier dynamics, adsorption/activation, and reaction on the surface of photocatalysts, which are the three main critical aspects for CO2 photoreduction and determine the overall photocatalytic efficiency. In view of the merits of porous materials, recent progress of three other types of porous materials are also briefly summarized, namely zeolite‐based, covalent–organic frameworks based (COFs‐based), and porous semiconductor or organic polymer based photocatalysts. The remarkable performance of these porous materials for solar‐driven CO2 reduction systems is highlighted. Finally, challenges and opportunities of porous materials for photocatalytic CO2 reduction are presented, aiming to provide a new viewpoint for improving the overall photocatalytic CO2 reduction efficiency with porous materials., Porous materials, including metal–organic frameworks, covalent organic frameworks, zeolites, and inorganic/organic porous semiconductors used for photocatalytic CO2 reduction are reviewed. Porous materials have been intensively exploited in solar‐driven CO2 reduction reactions for making valuable fuels. Three critical aspects of CO2 photoreduction are summarized and discussed, which provide new guidance for the future practical applications of porous materials.

In this work, hexagon-shaped potassium ferrite (K2Fe4O7) crystals with different sizes were prepared using the hydrothermal method. The crystals showed a narrow band gap of 1.44 eV, revealed by UV-visible diffuse reflectance spectroscopy, and was thus used as a heterogeneous Fenton catalyst to degrade methylene blue (MB) and crystal violet (CV) in the presence of green oxidant H2O2 under visible-light irradiation. Among the investigated crystals, the as-prepared one with an average size of 20 &micro, m (KFO-20) exhibited better photocatalytic activity due to its high surface area. When it was used as a photo-Fenton catalyst, 100% MB and 92% CV were degraded within 35 min. Moreover, the catalyst maintained high photocatalytic activity and was stable after four continuous cycles. The trapping experiments showed that the active hydroxyl radical (&middot, OH) was dominant in the photo-Fenton reaction. Therefore, this new photo-Fenton catalyst has great potential for the photocatalytic degradation of dye contaminants in water.

Flexible MoO3−x films were prepared by anodic oxidation followed by annealing and liquid-phase reduction. The prepared samples were characterized by XRD, Raman spectra, SEM, UV–visible spectrophotometer, XPS, and EPR. The anodized amorphous MoO3 was transferred to the orthorhombic phase during the annealing. With the increase in annealing temperature, the MoO3 films’ photocatalytic activity increased. After liquid-phase reduction, defects, including oxygen vacancies, were introduced. The defect introduction enhanced the visible light absorption and increased the charge transfer efficiency to varying degrees. Compared with the as-annealed MoO3 films, the as-reduced MoO3 films’ photocatalytic activity rose by nearly four times at most. With the increase in reduction time, the bulk defect concentration increased. However, the surface defect concentration reached the maximum when the reduction time came to 2 h. The most excellent photocatalytic activity corresponded to the largest surface defect concentration, suggesting surface defects improved the photocatalytic activity. On the other hand, the bulk defects had the opposite effect. The photogenerated holes played a crucial role in the photocatalytic degradation of MB. Anodic oxidation followed by annealing and liquid-phase reduction is a facile and effective way to prepare MoO3 films with high photocatalytic activity.

The hydrothermal method was used to prepare flexible BiOCl-BiOI films on one stainless steel wire mesh. Nano-flower like BiOCl-BiOI crystals consisted of nanoplates were formed, and BiOCl was uniformly distributed. The XPS (X-ray photoelectron spectroscopy) spectra confirm the formation of BiOCl-BiOI heterojunction, which enhanced the visible light absorption of the BiOI film. The photocatalytic activity of the BiOCl-BiOI film in degrading RhB and MB was elevated by at most 8.7 and 2.4 times, respectively, comparing with the individual BiOI film. We designed and constructed a piezo/photocatalytic platform in which the prepared BiOCl-BiOI films were fixed on a rotating shaft. Compared with the static state, the photocatalytic activity of the BiOCl-BiOI film was increased by 1.4 times when the shaft was rotating. We believe that the enhancement of the photocatalytic activity should be ascribed to the piezoelectric field by introducing bending deformation, which accelerated the separation of photogenerated electrons and holes. The improvement mechanism of the photocatalytic and piezo/photocatalytic performance was proposed and discussed. The flexible BiOCl-BiOI heterojunction films show significant application potential in the pollution control of fluid fields such as rivers, oceans, waterfalls, and air.

A new AgCl/Ag/AgFeO2 composite was synthesized for the first time via a simple precipitation method. The very detailed characterizations were enforced in photocatalytic activity and stability. The photocatalytic performance was studied by the degradation of the rhodamine B (RhB, a cationic dye) under visible irradiation. The as-prepared AgCl/Ag/AgFeO2 photocatalyst exhibited excellent photocatalytic activity and stability under the visible light region compared to pure AgCl and AgFeO2. About 97.47% of RhB can be removed in 60 min by the optimized AgCl/Ag/AgFeO2 composite, which was ∼2.26 and ∼10.83 times as fast as that pure AgCl and pure AgFeO2. After three cycles visible light irradiation experiments found that degradation rate of RhB reached 76.35%, which was still higher than pure AgCl and AgFeO2. The obviously enhanced photocatalytic activity of AgCl/Ag/AgFeO2 composites can be attributed to the efficient separation of electron-hole pairs of the Z-scheme heterostructure between AgCl, Ag and AgFeO2. In this study, we also found the superoxide radicals ( O2−) was considered to be the dominant active radical in the degradation of dye.

Mechanical coating followed by thermal oxidation in the atmosphere was used to prepare TiO 2 /SnO 2 composite coatings. The coatings were characterized by X-ray diffraction (XRD), scanning electronic spectroscopy (SEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and so on. Results show that continuous rutile TiO 2 coatings decorated with discrete SnO 2 particles were formed during thermal oxidation at the temperature range of 873–1073 K. Through the temperature range, a small quantity of SnO was formed. However, tiny amount of Ti 2 O 3 was formed only when oxidation temperature was 1073 K. The surface topography evolution of rutile TiO 2 crystals during the thermal oxidation and relevant mechanism was also examined. Equiaxed, rod, columnar and needle TiO 2 crystals with nanoscale were formed at temperatures from 873–1073 K. The topography evolution indicates that the diffusion of oxygen species into the formed rutile TiO 2 layer was predominant at 873 K. It favored the growth of equiaxed crystals in the tangent plane rather than radial direction of Al 2 O 3 ball substrate at the early stage of the thermal oxidation. However, the diffusion of Ti cations became prevailing compared with oxygen species at 1073 K. The reaction of Ti and oxygen species occurred at the external surface of the formed TiO 2 layer where rutile TiO 2 needles were formed. During thermal oxidation at 973 K, both the Ti cations and oxygen species were involved in the diffusion process and clusters of paired/parallel rutile TiO 2 nanorods were formed. The addition of metallic Sn remarkably affected the surface topography and the grain size of rutile TiO 2 crystals through regulating the diffusion of Ti cations and changing the local oxygen concentration surrounding Ti coatings. A proper additive amount refined the grains of rutile TiO 2 .

With good high temperature and corrosive resistance performance, ceramic based composites can be used as promising materials to replace metal thermocouple materials. In this study, Si3N4&ndash, MoSi2 composites were prepared via hot pressing technology. X-ray diffraction (XRD), optical microscopy (OM), and scanning electron microscopy (SEM) were used to analyze the microstructure of the composites. The mechanical properties and electrical conductivity were tested. The results showed that the composites were composed of &beta, Si3N4, MoSi2, a small amount of Mo5Si3, and an amorphous glassy phase. The MoSi2 phase was evenly distributed in the matrix. The percolation network was formed with increasing MoSi2 content. The strength of the composites reached its maximum value when the MoSi2 content reached a critical point. The electrical conductivity behaved like a typical percolation phenomenon. The percolation threshold was about 30% to 45%.

With good high temperature and corrosive resistance performance, ceramic based composites can be used as promising materials to replace metal thermocouple materials. In this study, Si3N4–MoSi2 composites were prepared via hot pressing technology. X-ray diffraction (XRD), optical microscopy (OM), and scanning electron microscopy (SEM) were used to analyze the microstructure of the composites. The mechanical properties and electrical conductivity were tested. The results showed that the composites were composed of β-Si3N4, MoSi2, a small amount of Mo5Si3, and an amorphous glassy phase. The MoSi2 phase was evenly distributed in the matrix. The percolation network was formed with increasing MoSi2 content. The strength of the composites reached its maximum value when the MoSi2 content reached a critical point. The electrical conductivity behaved like a typical percolation phenomenon. The percolation threshold was about 30% to 45%.

This paper mainly investigates the fracture problem of U71Mn rail flash-butt welding joint. Fracture surface morphology, microstructure and micro hardness are analyzed by using the scanning electron microscopy (SEM/EDS), the optical microscope (OM) and the micro Vickers hardness tester (Vickers-tester). The analysis results show that the welding joint is fatigue fracture, and the fracture surface morphology is the cleavage fracture characteristics. The metallographic morphology, inclusions and micro-hardness near the fracture surface are all in the normal levels. On the other side, the free solidification microstructure which extended from the outside to inside in the joint of the left side of the rail web and the rail head is the crack source of the rail welding joint fatigue fracture. Under the action of bending stress, the crack firstly generates in this area, and gradually extended to the rail web, to final fracture.

The damage behaviors of Ti–6Al–4V alloy targets with two different states (aged state and annealed state) and three different thickness (thin, medium, and semi-infinite) impacted by 4 mm diameter GCr15 steel ball at a speed of 2.0 km/s were studied. The results show that the strength of the targets with aged state is higher than those with annealed state at two different strain rates. In the semi-infinite thickness targets, the depth and diameter of the crater in the targets with annealed state are similar to those with the aged state, but the volume of the crater in the annealed targets is about 1.5 times higher than those with the aged state. In the medium thickness targets, after being impacted, a plug was clearly formed in the rear of the targets with aged state, and a bulge was formed on the back face of the targets with annealed state. Abundant adiabatic shear bands were observed near the craters. Abundant adiabatic shear bands intercept each other and formed a net structure. The density and distribution range of abundant adiabatic shear bands in the targets with aged state are larger than those with annealed state. Two straight abundant adiabatic shear bands extending along tangential direction were observed and connected with the plug. Micro-voids nucleate, grow and coarsen in the abundant adiabatic shear bands, which leads to a premature failure.

Based on best track data of tropical cyclones (TCs) from the Japan Meteorological Agency, the characteristics of suddenly reversed TCs (SRTCs), which have turning angles usually approaching 180°, are statistically analyzed from 1949 to 2011 over the western North Pacific Ocean. The typical large-scale circulation patterns of SRTCs are investigated using reanalysis data and dynamical composite analysis. Results show that turnings mainly occur in low latitudes between 10°N and 20°N, and mainly west of 135°E. The majority of SRTCs reach their peak intensity at, or slightly before, the turning time and subsequently decrease at some variable rate. Specifically, SRTCs are divided into four types, each containing two groups (i.e. eight groups in total) in terms of the moving-direction changes. The moving speed of all SRTC types except the south-north type decreases to its lowest during the 24 h, corresponding to a significant reduction in the primary steering components. According to the analysis of the 13 typical flow patterns found in this study, we suggest that sudden track changes are caused by the reversal steering flow. The original balance of the background flow patterns are broken up by new systems, e.g. binary TCs or dispersion-induced anticyclones. Additionally, sudden track changes are often due to double ridge variations of the subtropical high or weakened/strengthened high pressure in the east and west, respectively.

In 2010, Supertyphoon Megi experienced an abrupt track deflection in the South China Sea (SCS) after traversing Luzon Island. To reveal the physical processes responsible for the timing and location of the sudden track deflection, the potential vorticity (PV) diagnosis and numerical simulations with initial strength perturbations are applied to investigate the individual and combined effects of environmental systems on Megi’s motion based on the steering flow theory. Results indicate that Megi’s northward track deflection was mainly determined by the effect of the midlatitude circulation, or rather, the break of the high pressure belt joined by the continental high (CH) and the Pacific subtropical high (SH). The retraction of CH played a particularly critical role in the break of the high pressure belt, making it the most important feature of the midlatitude circulation to determine Megi’s deflection. In addition, a small low-latitude anticyclone (SA) southeast of Megi was crucial in affecting the timing and location of the deflection, although the steering effect provided by SA itself was relatively weak. The development of SA was associated with both the tropical cyclone energy dispersion and the activity of an easterly wave. This study suggests that the abrupt track deflection of Megi was attributed to the combined effect of the midlatitude and low-latitude systems, in addition to the combined effects of the large-scale and small-scale systems.

SiCP/Al–Fe–V–Si (Al–Fe–V–Si reinforced with SiC particles) composite prepared by spray deposition was densified by hot pressing and then rolled into sheets. Microstructure of the composite was observed, and fracture properties and fractographies of the composite at different tensile temperatures were investigated. The results show that uniform distribution of SiC particles and strong bonding between the particles and the matrix are obtained by rolling after hot pressing. It is found that fracture properties and fractographies of the composite are affected by the distribution and orientation of SiC particles. The composite is characterized by the fractographies of the composite varying with the elevation of temperature. Cracking of SiC particles is the dominant rupture mode because of the strong interface bonding with the tensile temperature below 300 °C. Debonding at SiC/Al matrix interfaces becomes the dominant rupture mode with tensile temperature above 300 °C, particles breakage reduces sharply as the ...

In our previous work, a thrombin-like enzyme (TLE), agkihpin, was successfully isolated, purified, cloned and named from the venom of Gloydius halys Pallas, having fibrinolytic, fibrinogenolytic and thrombosis-reduced activities, attenuating migration of liver cancer cell, and without bleeding risk. To explore the possibility of agkihpin as a thrombolytic and/or anti-metastasis agent in the future, in this study recombinant agkihpin was expressed and purified in Escherichia coli, and its biological activities investigated. Thus, r-agkihpin-2 was successfully expressed and purified and confirmed by Western blot and peptide mass fingerprinting. After purification and renaturation, 46 mg (399 U) of active r-agkihpin-2 was obtained from 1 L bacterial culture. The results of the arginine esterase activity assay, fibrin plate test fibrinogenolytic activity assay, thrombin-induced venous thrombosis assay, Scratch-Wound assay and bleeding assay showed that active r-agkihpin-2 had slightly lower TAME hydrolytic, fibrinolytic, fibrinogenolytic, thrombus-reduced and migration-attenuated activities than those of native agkihpin, and had no bleeding risk. These findings confirmed that, active r-agkihpin-2 could be further investigated for thrombolytic and/or anti-metastasis drug discovery in the future.

The pantograph contact strip is a sliding current collecting component used in electric locomotive. Its performance is an important factor restricting the development of electrified railways toward high speed. This paper makes an introduction of the new developing composite material strips, points out the advantages and disadvantages of various materials, their limiting factors during using or bottlenecks in R&D and production, and gives prospect to the future development of pantograph contact strip materials in the end.

Multi-layer spray deposited Al–8.5Fe–1.3V–1.7Si alloy was co-deposited with 15 vol% SiC particulate (SiCP). The microstructure of the composite as-rolled has been determined using transmission electron microscopy (TEM). Elevated temperature properties of the composite have been investigated by comparing the tensile mechanical properties at 20°C, 315°C and 400°C for the composite. The significance of these results for microstructure at elevated temperature, operating strengthening mechanisms and the effects of SiCP reinforcement in such an alloy system, is discussed.

Al–Fe–V–Si alloys reinforced with SiC particles were prepared by multi-layer spray deposition technique. Both microstructures and mechanical properties including hardness and tensile properties development during hot exposure process of Al–8.5Fe–1.3V–1.7Si, Al–8.5Fe–1.3V–1.7Si/15 vol% SiCP and Al–10.0Fe–1.3V–2Si/15 vol% SiCP were investigated. The experimental results showed that an amorphous interface of about 3 nm in thickness formed between SiC particles and the matrix. SiC particles injected silicon into the matrix; thus an elevated silicon concentration was found around α-Al12(Fe, V)3Si dispersoids, which subsequently inhibited the coarsening and decomposition of α-Al12(Fe, V)3Si dispersoids and enhanced the thermostability of the alloy matrix. Moreover, the thermostability of microstructure and mechanical properties of Al–10.0Fe–1.3V–2Si/15 vol% SiCP are of higher quality than those of Al–8.5Fe–1.3V–1.7Si/15 vol% SiCP.

Ni-Al2O3 nanocomposite coatings were fabricated by jet electrodeposition process. Effect of concentration of Al2O3 in the electrolyte, current density and electrolyte jet speed on nano-Al2O3 content were analyzed. The composite coatings’ micro structure, energy spectrum was observed under the scanning microscope(SEM). Effect of nano-Al2O3 content on the microhardness and corrosion resistance were evaluated. The results shows that the Ni deposited layers have nanocrystalline micro structure with average size of 50 nm. Al2O3 particles are well dispersed in layer and the particles content is up to 12.2 at %. Microhardness of the coating increase, bond strength and corrosion resistance of the coatings first increase then decrease with increase of Al2O3. content in coatings.