Solution‐reprocessable microporous polymeric adsorbents for carbon dioxide capture

Solution‐processable microporous polymers are promising materials for CO₂ capture because of their low synthetic cost and high processability. In this work, we for the first time systematically evaluate the feasibility of two microporous polymers, namely PIM‐1 and its hydrolyzed form hPIM‐1, as adsorbent materials for postcombustion CO₂ capture. By conducting ternary CO₂/N₂/H₂O breakthrough experiments, PIM‐1 demonstrates several promising features: moderate CO₂ working capacity, low water vapor uptake capacity, good moisture resistance, and easy regeneration process. In addition, we have pioneeringly studied the multiple‐cycle CO₂ adsorption–desorption induced relaxation effect on soft PIM‐1 polymers. Through a simple dissolution–precipitation approach, PIM‐1 can restore its BET surface area, CO₂ uptake capacity, and pore‐size distribution. The solution reprocessability of PIM‐1 demonstrated in this study distinguishes it from other rigid adsorbents and thus offers a new insight for the future design of economically‐viable and facilely regenerable adsorbents. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3376–3389, 2018     

Feature extraction method of abrasive belt wear state for rail grinding

Abstract

Abrasive belt has the advantages of high removal efficiency and high waste collection; furthermore, it does not easily damage the rail when applied in rail grinding. However, the poor wear consistency and short service life restrict its development in this field. It is important to explore the theory and technology of monitoring the abrasive belt wear condition to evaluate the means of improving the grinding performance of the belt. This article discusses the contact stress state between the belt and the rail surface. In addition, the study establishes the belt rail grinding force model during operation using the abrasive grain distribution function. The analysis of the force model proposes that the belt abrasion condition be monitored by using the force ratio parameter of the abrasive belt in the grinding process. The extraction method of the force ratio information is proposed in accordance with the grinding environment. The results of experiments successfully verified the validity of the method.     

Biomimetic Cleavage of Aryl–Nitrogen Bonds in <Emphasis Type="Italic">N</Emphasis>-Arylazoles Catalyzed by Metalloporphyrins

The cleavage of C–N single bonds of N-containing compounds provides either an excellent nitrogen source or an excellent carbon source. In this study, an efficient metalloporphyrins/H₂O₂ cleavage of C–N bonds of arylpyrazoles was investigated. The effects of different factors, including different catalysts, catalyst dosages, H₂O₂ dosages, reaction temperature and reaction time were studied. The experimental results showed that the optimal catalyst was FeTPPCl, and the yield of pyrazole derivatives could reach up to 12.3%, which was fourfold higher than hemin catalyzed reaction and closed to ceric ammonium nitrate catalyzed reaction, respectively. Compared with transition-metal-catalyzed and strong-oxidization cleavage of C–N bonds, this protocol is characterized by environmentally-friendly, stable, mild reaction conditions and simplified operation procedures.

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Investigation of the μN level adhesion force characteristics of gold-coated materials in air

The typical adhesive phenomena of gold-coated contact material under cold switching conditions are observed using a micro-adhesion apparatus as a switch simulator. With repeated actuation, the recorded adhesion force results uniformly show a Gaussian-like distribution. Moreover, the effects of curvature radius of contact and contact force on adhesive force are investigated experimentally. For better understanding of the adhesion mechanism, the theoretical analysis model is built by introducing the Hamaker’s discussion about the interaction between a pair of neutral atoms or molecules. Data suggest that the substantial increase of adhesion force is correlated closely with the microscopic contact area.     

Gamma radiation effect of polymethylvinylphenylsiloxane rubbers under different temperatures

The gamma radiation effect on polymethylvinylphenylsiloxane (PMVPS) rubbers is investigated by irradiation exposure of PMVPS rubbers to a maximum dose of 200 kGy in the temperature range 28–110 °C. Compared with unirradiated PMVPS rubber, the elongation at break of irradiated PMVPS rubber decreases while its elastic modulus increases with the increase of absorbed dose or radiation temperature. DSC, ATR‐FTIR, XPS, and ¹H‐NMR indicate that slight degradation and oxidation reaction occur during the irradiation of PMVPS. Solvent swelling and gel fraction study confirms that the crosslinking density of PMVPS rubbers increases gradually with increasing absorbed dose or radiation temperature. Therefore, radiation‐induced crosslinking of PMVPS is dominant reactions for the chosen dose or temperature range. Furthermore, synergistic effect exists in the high‐temperature radiation process for PMVPS rubbers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45404.     

High‐temperature electrical and thermal transport behaviors in layered structure WSe2

Two‐dimensional transition‐metal dichalcogenides semiconductors (TMDCs) with layered structures have been concerned as promising thermoelectric (TE) materials for several years. However, WSe₂ as one of TMDCs is barely investigated. Herein, we systematically investigated the high‐temperature electrical and thermal transport behaviors in layered structure WSe₂, demonstrating that WSe₂ possesses high Seebeck coefficient and low thermal conductivity. The study of sintering process shows that the best electrical properties can be obtained in the sample sintered at 1123 K. Besides, anisotropic thermoelectric properties were also revealed. It is found that the dimensionless figure of merit (ZT) in the direction parallel to the pressing direction is higher than that in the direction perpendicular to the pressing direction. The highest ZT value of 0.03 is obtained at 923 K, which is an appreciable value for the pristine alloy material.     

Polytriazole polyether elastomers with widely tunable mechanical properties: The role of network structure and crystallization behavior

The polytriazole polyether elastomers were prepared by the propargyl‐terminated ethylene oxide‐tetrahydrofuran [PTP(E‐co ‐T)] prepolymer and the multi‐azide group glycidyl ether with different curing parameter R . The relationship between the network structure, mechanical properties, and crystallization behaviors of the elastomers were investigated by swelling testing, tensile testing machine, differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD), and in situ wide‐angle X‐ray scattering at 60, 20, and ?40 °C, respectively. The mechanical properties of the polytriazole elastomers exhibited obviously different dependences on R values at different testing temperatures. At 60 and 20 °C, with the increase of R , the tensile stress at breaking gives a parabola going downwards with a maximum at R = 1.1. However, at ?40 °C, the stress exhibited an analogous parabola going upward with a minimum at R = 1.1. The DSC and WAXD results indicated that at 60 and 20 °C, the polytriazole elastomers was amorphous, but at ?40 °C, the polytriazole elastomers were crystallizable and the crystallization capability of the polytriazole elastomers are also observed. Therefore, it can be inferred that at 60 and 20 °C, the mechanical properties of the polyether polytriazole elastomer depend on completeness of the network structures, while the crystallization behavior of the polytriazole elastomers induces its different mechanical properties at ?40 °C. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45298.     

连续反应釜中γ-十一内酯合成宏观动力学研究

研究了γ-十一内酯合成过程中包含可逆的主反应和丙烯酸聚合副反应的宏观动力学,为提高反应选择性提供了动力学依据。实验在连续操作的釜式反应器中进行,考察不同温度、不同进料流量条件下反应速率,利用实验数据对模型进行参数拟合,得到主反应和副反应动力学参数,经统计检验和残差分析表明,所建立的动力学模型可靠,可用于宏观描述该反应。研究结果证明:提高反应温度,降低丙烯酸浓度有利于提高主反应选择性、提高γ-十一内酯收率。     

Eradication of Multidrug‐Resistant Staphylococcal Infections by Light‐Activatable Micellar Nanocarriers in a Murine Model

Bacterial infections are mostly due to bacteria in their biofilm mode‐of‐growth, making them recalcitrant to antibiotic penetration. In addition, the number of bacterial strains intrinsically resistant to available antibiotics is alarmingly growing. This study reports that micellar nanocarriers with a poly(ethylene glycol) shell fully penetrate staphylococcal biofilms due to their biological invisibility. However, when the shell is complemented with poly(β‐amino ester), these mixed‐shell micelles become positively charged in the low pH environment of a biofilm, allowing not only their penetration but also their accumulation in biofilms without being washed out, as do single‐shell micelles lacking the pH‐adaptive feature. Accordingly, bacterial killing of multidrug resistant staphylococcal biofilms exposed to protoporphyrin IX‐loaded mixed‐shell micelles and after light‐activation is superior compared with single‐shell micelles. Subcutaneous infections in mice, induced with vancomycin‐resistant, bioluminescent staphylococci can be eradicated by daily injection of photoactivatable protoporphyrin IX‐loaded, mixed‐shell micelles in the bloodstream and light‐activation at the infected site. Micelles, which are not degraded by bacterial enzymes in the biofilm, are degraded in the liver and spleen and cleared from the body through the kidneys. Thus, adaptive micellar nanocarriers loaded with light‐activatable antimicrobials constitute a much‐needed alternative to current antibiotic therapies.     

Efficient Terahertz Plasmonic Absorbers with V-Grooves Using Highly Doped Silicon Substrate and Simple Wet-Etching Techniques

We experimentally demonstrate that at terahertz frequencies perfect plasmonic absorbers made from a 3D V-groove array in a highly doped silicon wafer can be easily realized using simple wet-etching process. The surface plasmon modes can be excited by the V-groove array and get decayed when they propagate along the silicon surface and enter the grooves, inducing a broadband near-zero dip in the reflection spectra. The reflection spectrum of the fabricated absorber is characterized using a terahertz time-domain spectroscopy system, and the experimental results are in good agreement with numerical simulations. The high performance including high absorptivity and large bandwidth together with the easy fabrication processes presented in this paper make this plasmonic absorber promising for a wide range of practical applications in terahertz regime.