Spark plasma sintering synthesis of intermetallic T2 in the Mo–Si–B system

Mo₅SiB₂ (T2) was synthesized by sparking plasma sintering (SPS) under different heating rates and sintering temperatures. The powder mixture with a T2 composition (Mo–12.5Si–25B (at.%)) failed to produce the T2 single-phase alloy due to the volatilization of Si during SPS process. Extra 0.5 at.% Si added to this mixture offset the volatilization loss. It has been found that heating of the mixture at low heating rates favored the formation of binary phases in the solid state at medium temperatures. In this work, the T2 alloy with a fine-grained microstructure was obtained via a liquid–solid reaction when the mixture was heated fleetly to the temperatures above the silicon melting point at the rapid heating rate of 200 °C/min. The sintering temperature at 1500 °C for T2 synthesis is beneficial to enhance further densification, as well as to avoid abnormal grain growth at higher temperatures.     

Have Chinese universities embraced their third mission? New insight from a business perspective

Have Chinese universities, after enormous investment over the past decade, embraced the university’s third mission—contributing to industrial and technological progress? The literature has not sufficiently addressed this question. This study intends to advance understanding of this issue by empirically addressing this question from a business perspective in a bold and unconventional way. Unlike prior studies that simply used contingent and institutional factors to describe the link between Chinese universities and industrial firms by measuring such aspects as patent licensing, co-patenting, and co-authoring, our work goes further and applies longitudinal analysis to examine the ways firms access university-level knowledge and the impact of such knowledge on firm innovation outputs. We propose that if Chinese universities embraced their third mission, then we would observe a positive effect of university–industry collaborations on firms’ subsequent innovation outputs. Empirical results based on a sample of the top 100 Chinese electronic firms in terms of output value support our hypothesis. Specifically, university patent licensing and co-patenting between universities and firms was found to positively affect firm innovation outputs. Moreover, we found that geographical distance and collaboration dominance moderate the co-patenting–innovation output relationship.     

Cooperative effect of molecular orientation and β-form on toughening injection-molded isotactic polypropylene with β-nucleating agent

The toughness of conventional injection-molded isotactic polypropylene bars has been investigated with respect to the notch location and β-nucleating agent. Superior toughness is achieved in the β-nucleated bars with notches near the gate, but is absent in the near-gate bars without β-nucleating agent or in the β-nucleated ones far from the gate. With detailed structural analysis across the sample thickness, it is indicated that in these tough bars, extensive flow close to the surface suppresses the formation of β-form to a large extent but favors the generation of oriented α-form, whereas toward inner region, an opposite tendency is presented with the decay of flow strength and the activation of β-nucleating agent. Allowing that this peculiar hierarchical structure is absent in other two kinds of bars, it is deduced that the cooperative effect of molecular orientation of α-form in the skin layer and rich β-form in the inner region is responsible for the significant toughness enhancement in the β-nucleated bars near the gate. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

浅析汽轮机转子热稳定性试验的双金属特性

根据汽轮机转子3次热稳定性试验数据,作出挠度、温度随时间变化的曲线,分析挠曲类型得出:某些转子热稳定性试验中存在双金属特性,即转子挠度随温度上升而增大,最高温度时达到最大值,冷却时随温度降低而降低;第1次热稳定性试验不合格的转子,若存在明显的双金属特性,可降低试验温度至进汽温度再次进行热稳定性试验。     

Single-machine-based predictive maintenance model considering intelligent machinery prognostics

As an increasing number of manufacturers are beginning to realize the importance of maintaining throughput, many maintenance models have been developed to enable machines to achieve near-zero downtime. However, previous maintenance models usually ignore machine’s deterioration process. Therefore, this paper develops a novel data-driven machinery prognostic approach for machine performance assessment and prediction. With this prognostic information, a predictive maintenance model is proposed for a repairable deteriorating machine. As machine performance can be assessed, once it reaches the maintenance threshold, a maintenance operation is performed to restore the machine. Moreover, an operational cost is introduced to meet real manufacturing process. In this predictive maintenance model, the optimal maintenance threshold and maintenance cycle number are obtained with the aim to minimize the long-term average cost. Finally, a case study is presented. The computational results show the efficiency of this proposed predictive maintenance model.     

Microstructural Modeling of Pitting Corrosion in Steels Using an Arbitrary Lagrangian–Eulerian Method

Metallurgical and Materials Transactions A - Two microscale numerical models are developed in this work using a moving-mesh approach to investigate the growth process of pitting in different iron...     

Single transition metal atom catalysts on Ti2CN2 for efficient CO2 reduction reaction

Electrochemical CO₂ reduction reaction (CO₂RR) is an efficient way in the utilization of CO₂. In this work, single transition-metal (TM) atom (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) anchored on two-dimensional (2D) Ti₂CN₂ are designed for CO₂RR using density-functional-theory (DFT) calculation. We show that Ti₂CN₂ serves as an excellent substrate to support single atom catalysts (SACs), compared to Ti₂CO₂ and Ti₂CF₂. We find that the Sc, Ti and V supported on Ti₂CN₂ show high catalytic activities to produce CO with a low overpotential of 0.37, 0.27, and 0.23 eV, respectively. Differently, the Mn and Fe on Ti₂CN₂ are catalytically active for the production of HCOOH with a low overpotential of 0.32 and 0.43 eV, respectively. We further show that the negatively charged TM-Ti₂CN₂ can capture and activate CO₂ more effectively, and the catalytic activity and selectivity can be significantly tuned by injecting extra electrons.     

Enhancing the Nucleolytic Resistance and Bioactivity of Functional Nucleic Acids by Diverse Nanostructures through in Situ Polymerization-Induced Self-assembly

Functional nucleic acids (FNAs) are garnering tremendous interest owing to their high modularity and unique bioactivity. Three-dimensional FNAs have been developed to overcome the issues of nuclease degradation and limited cell uptake. We have developed a new facile approach to the synthesis of multiple three-dimensional FNA nanostructures by harnessing photo-polymerization-induced self-assembly. Sgc8 aptamer and CpG oligonucleotide were modified as macro chain-transfer reagents to mediate in situ polymerization and self-assembly. Diverse structures, including micelles, rods, and short worms, afford these two FNAs afford these two FNAs with higher nuclease resistance in serum serum, greater cellular uptake efficiency, and increased bioactivity.     

Experimental Investigation on the Mechanical Instability of Superelastic NiTi Shape Memory Alloy

In this paper, primary attention is paid to the mechanical instability of superelastic NiTi shape memory alloy (SMA) during localized forward transformation at different temperatures. By inhibiting the localized phase transformation, we can obtain the up-down-up mechanical response of NiTi SMA, which is closely related to the intrinsic material softening during localized martensitic transformation. Furthermore, the material parameters of the up-down-up stress-strain curve are extracted, in such a way that this database can be utilized for simulation and validation of the theoretical analysis. It is found that during forward transformation, the upper yield stress, lower yield stress, Maxwell stress, and nucleation stress of NiTi SMA exhibit linear dependence on temperature. The relation between nucleation stress and temperature can be explained by the famous Clausius-Clapeyron equation, while the relation between upper/lower yield stress and temperature lacks theoretical study, which needs further investigation.