Surface-Enriched Single-Bi-Atoms Tailoring of Pt Nanorings for Direct Methanol Fuel Cells with Ultralow-Pt-Loading.

Single-atom decorating of Pt emerges as a highly effective strategy to boost catalytic properties, which can trigger the most Pt active sites while blocking the smallest number of Pt atoms. However, the rational design and creation of high-density single-atoms on Pt surface remain as a huge challenge. Herein, a customized synthesis of surface-enriched single-Bi-atoms tailored Pt nanorings (SE-Bi1/Pt NRs) toward methanol oxidation is reported, which is guided by the density functional theory (DFT) calculations suggesting that a relatively higher density of Bi species on Pt surface can ensure a CO-free pathway and accelerate the kinetics of *HCOOH formation. Decorating Pt NRs with dense single-Bi-atoms is achieved by starting from PtBi intermetallic nanoplates (NPs) with intrinsically isolated Bi atoms and subsequent etching and annealing treatments. The SE-Bi1/Pt NRs exhibit a mass activity of 23.77 A mg-1 Pt toward methanol oxidation in alkaline electrolyte, which is 2.2 and 12.8 times higher than those of Pt-Bi NRs and Pt/C, respectively. This excellent activity endows the SE-Bi1/Pt NRs with a high likelihood to be used as a practical anodic electrocatalyst for direct methanol fuel cells （DMFCs） with high power density of 85.3 mW cm-2 and ultralow Pt loading of 0.39 mg cm-2.

Atomic Diffusion Engineered PtSnCu Nanoframes with High-Index Facets Boost Ethanol Oxidation.

Electrochemical ethanol oxidation is crucial to directly convert a biorenewable liquid fuel with high energy density into electrical energy, but it remains an inefficient reaction even with the best catalysts. To boost ethanol oxidation, developing multimetallic nanoalloy has emerged as one of the most effective strategies, yet faces a challenge in the rational engineering of multimetallic active-site ensembles at atomic-level. Herein, starting from typical PtCu nanocrystals, an atomic Sn diffusion strategy is developed to construct well-defined Pt47Sn12Cu41 octopod nanoframes, which is enclosed by high-index facets of n (111)-(111), such as {331} and {221}. Pt47Sn12Cu41 achieves a high mass activity of 3.10 A mg-1 Pt and promotes the C-C bond breaking and oxidation of poisonous CO intermediate, representing a state-of-the-art electrocatalyst toward ethanol oxidation in acidic electrolyte. Density functional theory （DFT） calculations have confirmed that the introduction of Sn improves the electroactivity by uplifting the d-band center through the s-p-d coupling. Meanwhile, the strong binding of ethanol and the reduced energy barrier of CO oxidation guarantee a highly efficient ethanol oxidation process with improved Faradic efficiency of C1 products. This work offers a promising strategy for constructing novel multimetallic nanoalloys tailored by atomic metal sites as the efficient electrocatalysts.

Tenecteplase versus alteplase in treatment of acute ST-segment elevation myocardial infarction: A randomized non-inferiority trial.

BACKGROUND: A phase II trial on recombinant human tenecteplase tissue-type plasminogen activator (rhTNK-tPA) has previously shown its preliminary efficacy in ST elevation myocardial infarction (STEMI) patients. This study was designed as a pivotal postmarketing trial to compare its efficacy and safety with rrecombinant human tissue-type plasminogen activator alteplase (rt-PA) in Chinese patients with STEMI. METHODS: In this multicenter, randomized, open-label, non-inferiority trial, patients with acute STEMI were randomly assigned (1:1) to receive an intravenous bolus of 16 mg rhTNK-tPA or an intravenous bolus of 8 mg rt-PA followed by an infusion of 42 mg in 90 min. The primary endpoint was recanalization defined by thrombolysis in myocardial infarction (TIMI) flow grade 2 or 3. The secondary endpoint was clinically justified recanalization. Other endpoints included 30-day major adverse cardiovascular and cerebrovascular events (MACCEs) and safety endpoints. RESULTS: From July 2016 to September 2019, 767 eligible patients were randomly assigned to receive rhTNK-tPA ( n = 384) or rt-PA ( n = 383). Among them, 369 patients had coronary angiography data on TIMI flow, and 711 patients had data on clinically justified recanalization. Both used a -15% difference as the non-inferiority efficacy margin. In comparison to rt-PA, both the proportion of patients with TIMI grade 2 or 3 flow (78.3% [148/189] vs. 81.7% [147/180]; differences: -3.4%; 95% confidence interval [CI]: -11.5%, 4.8%) and clinically justified recanalization (85.4% [305/357] vs. 85.9% [304/354]; difference: -0.5%; 95% CI: -5.6%, 4.7%) in the rhTNK-tPA group were non-inferior. The occurrence of 30-day MACCEs (10.2% [39/384] vs. 11.0% [42/383]; hazard ratio: 0.96; 95% CI: 0.61, 1.50) did not differ significantly between groups. No safety outcomes significantly differed between groups. CONCLUSION: rhTNK-tPA was non-inferior to rt-PA in the effect of improving recanalization of the infarct-related artery, a validated surrogate of clinical outcomes, among Chinese patients with acute STEMI. TRIAL REGISTRATION: www.ClinicalTrials.gov (No. NCT02835534).

Enhancing the Electrical Conductivity and Strength of PET by Single-Wall Carbon Nanotube Film Coating.

Single-wall carbon nanotubes (SWCNTs) with excellent physicochemical properties are considered a promising candidate for the electrical and mechanical reinforcements of polymers. However, the poor dispersion of SWCNTs in plastics seriously limits their application and their achieved performance enhancement. Here, we coat a freestanding, highly conductive SWCNT film onto the surface of a polyethylene terephthalate (PET) film by a hot-pressing method. Due to the uniform SWCNT network structure and strong interfacial interaction, the SWCNT/PET hybrid film showed notably enhanced electrical and mechanical properties even though with a very low SWCNT weight fraction of 0.066%. The surface square resistance of the SWCNT/PET film decreased to 120-140 Ω/□ from 1016 Ω. In addition, Young's modulus and tensile strength of the SWCNT/PET film reached 4.6 GPa and 148 MPa, which are 31.3 and 24.4%, respectively, higher than the pure PET film. The SWCNT/PET film shows excellent mechanical durability and thermal stability, demonstrating its potential use as an antistatic material.

Effects of Cu and Ag Elements on Corrosion Resistance of Dual-Phase Fe-Based Medium-Entropy Alloys.

The effect of adding elements to promote phase separation on the functional properties of medium-entropy alloys has rarely been reported. In this paper, medium-entropy alloys with dual FCC phases were prepared by adding Cu and Ag elements, which exhibited a positive mixing enthalpy with Fe. Dual-phase Fe-based medium-entropy alloys were fabricated via water-cooled copper crucible magnetic levitation melting and copper mold suction casting. The effects of Cu and Ag elements microalloying on the microstructure and corrosion resistance of a medium-entropy alloy were studied, and an optimal composition was defined. The results show that Cu and Ag elements were enriched between the dendrites and precipitated an FCC2 phase on the FCC1 matrix. During electrochemical corrosion under PBS solutions, Cu and Ag elements formed an oxide layer on the alloy's surface, which prevented the matrix atoms from diffusing. With an increase in Cu and Ag content, the corrosion potential and the arc radius of capacitive resistance increased, while the corrosion current density decreased, indicating that corrosion resistance improved. The corrosion current density of (Fe63.3Mn14Si9.1Cr9.8C3.8)94Cu3Ag3 in PBS solution was as high as 1.357 × 10-8 A·cm-2.

In vitro corrosion and in vivo behavior of high strength Mg-6Zn-1Mn alloy wire for gastrointestinal anastomosis nail application.

Ti and its alloy staples can be retained in the human body for a long period because of their excellent corrosion resistance and thus requires revision surgery for removal. In this study, biodegradable Mg-6Zn-1Mn alloy staples were fabricated using ∼99.8 % area reduction cold drawing, whose service performance was evaluated by in vitro corrosion and in vivo tests. The high strength (∼340 MPa) of staples is mainly attributed to the formation of fine grains, nanoparticles, and additional dislocations. Moreover, owing to the effect of fine grains, as well as the high Schmid factor of prismatic ⟨a⟩ slip and pyramidal ⟨c+a⟩ slip, the staples also exhibit acceptable ductility (∼10 %). The in vitro corrosion results indicate that staple fractures occurred after immersion for 21 h in a single PBS solution. With the addition of ∼0.5 g/L bovine serum albumin (BSA), the time required to maintain the mechanical integrity of staples can expand to 90 h. This is mainly related to the adsorption and chelating effects between BSA and Mg matrix. After the implantation surgery, all rabbits fully recovered with normal oral intake, and Mg ions generated by degradation effectively promoted the absorption of the alimentary system. Therefore, the Mg-6Zn-1Mn alloy staples fabricated in this study exhibit desired effect, and excellent clinical application prospects.

Fabricate of High-Strength and High-Conductivity Cu-Cr-Si Alloys through ECAP-Bc and Aging Heat Treatment.

The effect of equal channel angular pressing (ECAP) through the route Bc and aging treatment on the grain structure and properties of the Cu-1Cr-0.2Si alloy was investigated. Microstructure was detected by scanning electron microscopy (SEM), x-ray diffraction (XRD), and electron backscatter diffraction (EBSD) and the mechanical properties and electrical conductivity were tested. Results shown that after ECAP, accompanying the grains refined to nano-and submicron-structure, the Cr particles were gradually spread along the grain boundaries (GBs), aging treatment promoted Cr particles dispersed in the matrix. ECAP greatly increased the ultimate tensile strength (UTS) while having a small effect on the conductivity, and aging treatment increased electrical conductivity. The stable {111}<110> texture after ECAP and the lower dislocation density after aging treatment maybe the main reasons for the high conductivity of the material.

Effect of Ceramic Capillary Parameters on Bonded Morphology and Strength.

The effects of the geometry parameters of a ceramic cleaver on the morphology of ball and second bonded points were studied using an automatic wire bonder, push pull tester, scanning electron microscope, ceramic capillary with different geometric parameters and φ25.4 µmAg-5Au bonding alloy wire, etc. The result shows that when the inner hole diameter (IHD) of the ceramic capillary is 1.3 times the diameter of the alloy wire (33 µm), the neck morphology of the ball bonded point (first bonded point) meet the requirements. The neck of the ball bonded point appeared to fracture when the IHD is 26 µm; The neck of the ball bonded point appeared as an irregular shape when the IHD is 41 µm. When the inner cutting angle diameter (ICAD) is 64 µm, the size of the mashed ball diameter (MBD) is qualified. When the ICAD is 51 µm, the MBD is too large and mashed ball overflows the pad. When the ICAD is 76 µm, the ball bonded point is too high. When the inner cutting bevel angle (ICBA) is 100°, the MBD size meets the requirements of the pad. When the ICBA was reduced to 70°, the ball bonded point is eccentric. When the ICBA was increased to 120°, the MBD is too large and is connected to the adjacent pad contact. The size of the fish tail of the second bonded point (second bonded point) changed in the same direction as the tip diameter (TD) changes. When the TD is 178 µm, the fish tail shape is regular and symmetrical. When the working face angle (WFA) is 8° and the outer circular radius (OCR) is equal to the diameter of the alloy wire (25.4 µm), the fish tail shape is regular. When the WFA is higher than 11° or the OCR is higher than 30 µm, the fish tail will appear as virtual welding, and when the WFA is less than 4°, the fish tail of the second bonded point will break due to thinning. When the OCR is less than 20 µm, the fish tail of the second bonded point is too long and causes a short circuit.

Study of the Dynamic Recrystallization Process of the Inconel625 Alloy at a High Strain Rate.

High-temperature compression and electron backscatter diffraction (EBSD) techniques were used in a systematic investigation of the dynamic recrystallization (DRX) behavior and texture evolution of the Inconel625 alloy. The true stress⁻true strain curves and the constitutive equation of Inconel625 were obtained at temperatures ranging from 900 to 1200 °C and strain rates of 10, 1, 0.1, and 0.01 s-1. The adiabatic heating effect was observed during the hot compression process. At a high strain rate, as the temperature increased, the grains initially refined and then grew, and the proportion of high-angle grain boundaries increased. The volume fraction of the dynamic recrystallization increased. Most of the grains were randomly distributed and the proportion of recrystallized texture components first increased and then decreased. Complete dynamic recrystallization occurred at 1100 °C, where the recrystallized volume fraction and the random distribution ratios of grains reached a maximum. This study indicated that the dynamic recrystallization mechanism of the Inconel625 alloy at a high strain rate included continuous dynamic recrystallization with subgrain merging and rotation, and discontinuous dynamic recrystallization with bulging grain boundary induced by twinning. The latter mechanism was less dominant.

Tensile mechanical performance of Ni-Co alloy nanowires by molecular dynamics simulation.

In this present contribution, tensile mechanical properties of Ni-Co alloy nanowires with Co content from 0 to 20% were studied by molecular dynamics. The simulation results show the alloy nanowire with the Co content of 5% has the highest yield value of 9.72 GPa. In addition, more Frank dislocations were generated during the loading process to improve the performance of the alloy nanowire. The Young's modulus increases little by little from 105.68 to 179.78 GPa with the increase of Co content. Secondly, with the increase of temperature, the yield strength gradually decreases to 2.13 GPa. Young's modulus tends to decrease linearly from 170.7 GPa to 48.21 GPa. At the temperatures of 500 K and 700 K, it is easier to form Frank dislocation and Hirth dislocation, respectively, in the loading process. The peak value of the radial distribution function decreases and the number of peaks decreases, indicating the disappearance of the ordered structure. Finally, after the introduction of the surface and inner void, the yield strength of the nanowire drops about to 8.97 and 6.6 GPa, respectively, and the yield strains drop to 0.056 and 0.043. In the case of the existence of internal void, perfect dislocation and Hirth dislocation can be observed in the structure.

Distribution, inhalation and health risk of PM2.5 related PAHs in indoor environments.

To investigate the potential cancer risk resulting from exposure to air pollutants, polycyclic aromatic hydrocarbons (PAHs) bound to airborne particles (PM2.5) were assessed in one outdoor environment and four indoor environments before and during the Spring Festival of 2015. The average total PAH concentration was site-dependent, and the concentration decreased before and during the Spring Festival. Fluoranthene (Flt) was the most commonly occurring among the 16 priority PAHs, and benzo(a)pyrene (BaP) accounted for the largest portion of the total carcinogenic potency of PAHs in PM2.5. The average BaP levels, in both indoor and outdoor environments, considerably exceeded the maximum permissible risk level of 1 ng/m3. Hazard quotients were found to be much less than 1, indicating little risk in terms of non-carcinogenic effects. Carcinogenic health risks resulting from possible carcinogens were determined to be much less than 1.00E-06. According to the California and WHO reference protocol, using empty room data to estimate the carcinogenic health risk produced values that were 10% lower than those calculated using outdoor environmental data.

Influence of fine-grain and solid-solution strengthening on mechanical properties and in vitro degradation of WE43 alloy.

As one of the most important potential candidate alloys for vascular stent application, Mg-Y-Zr based Mg-4.2wt%Y-2.4wt%Nd-0.6wt%Ce(La)-0.5wt%Zr (WE43) alloys were investigated in combination with the forming processes of micro-tubes with 2.0 mm diameter and 0.1 mm wall thickness. Orthogonal experimental design for alloy composition, vacuum melting ingot, heat treatment, integrated plastic deformation and micro-tube forward extrusion are included in the processing procedures. Significant improvements in both the mechanical properties and corrosion resistance in phosphate buffered saline solution for WE43 alloys were achieved through this processing sequence. The influence of the heat treatment and hot extrusion on in vitro degradation and plasticity was found to be associated with grain size reduction and the redistribution of intermetallic particles within the microstructure. As a result, the mechanical properties and the corrosion resistance of Mg alloys can be improved through fine-grain strengthening and solid-solution strengthening to some extent.

[Spectroscopic characterization and properties of Mg2B2O5w/AZ91D magnesium composites].

Magnesium borate whisker (Mg2B2O5 w) reinforced Mg matrix composite was fabricated by vacuum-gas pressure infiltration process. The Mg2B2O5 w preforms forming process was determined. The Mg2B2O5 whiskers were fabricated into a preform by wet forming method without any binder. The Vacuum-Gas Pressure Infiltration process and parameters are also developed. The micrographs revealed reasonably uniform distribution and random orientation of the whiskers in the as-cast Mg2B2O5 w/AZ91D composite and the composites were without pores defect. The phases were analyzed by XRD patterns for the as-received whiskers, the whiskers sintered at 1 000 degrees C for 3 h and the as-cast composite, respectively. Then, the microstructure evolution of the composite was investigated when the composite was heat-treated. Meanwhile, the relationships between microstructure and micro-hardness of the alloy heat-treated were also studied. The heat-treatment condition were solution at 415 degrees C for 8 and 24 h, respectively, aging treatment at 200 degrees C for 8, 12, 16, 20 and 24 h, respectively and solution at 415 degrees C for 8 or 24 h and subsequent aging treated for 8, 12, 16, 20, 24 h, respectively. The phases were analyzed by XRD patterns for the composites after different heat treated process. The results of XRD patterns were shown to be in good agreement with the microstructures evolution of the composites. The results showed that the micro-hardness of the solution treated composites is decreased due to resolution of eutectic phase, whereas the micro-hardness of the aged composites was increased gradually and the peak hardness is reached to 201 HV in the composite aged for 16 hours. Solution treatment at 415 degrees C for 24 h, the beta-Mg17, Al12 phase is dissolved in the alpha-Mg phase to form oversaturated solid-solution in the composite and then the diffusive beta phase precipitates after subsequent aging treatment at 200 degrees C for 8 h; hence the micro-hardness of the composite was increased 30%. However, as the aging time increased to 24 h, the hardness of the composite was reduced to 183 HV because the beta-Mg17 Al12 phase precipitate changed from continuous fine platelets to discontinuous coarse platelets. It was concluded that the process of solution at 415 degrees C for 24 h and subsequent aging treatment at 200 degrees C for 8 h was the best process for the composite.