Activity and selectivity enhancement of silica supported cobalt catalyst for alcohols production from syngas via Fischer-Tropsch synthesis

Synthesis of mixed alcohols together with clean fuels from syngas via Fischer-Tropsch synthesis is an attractive route for the utilization of coal, natural gas and biomass. In this work, a monometallic cobalt catalyst (Co/SiO₂-EOAM) was synthesized by impregnation using ethanolamine modified silica pellet as support and employed for the conversion of syngas. The combustion of carbon and nitrogen species during the calcination of catalyst facilitated the interaction between cobalt and support, which promoted the cobalt dispersion while inhibited the reduction of cobalt oxide. The Co/SiO₂-EOAM catalyst exhibited much higher activity and selectivity to alcohols compared to un-modified silica supported cobalt catalyst (Co/SiO₂). The higher activity was resulted from the improved cobalt dispersion. The co-existence of abundant metallic cobalt and Co²⁺ species were responsible for the increasing of alcohols selectivity.     

(1-x)Bi0.5Na0.47Li0.03TiO3-xNaNbO3 lead-free ceramics with superior energy storage performances and good temperature stability

Dielectric capacitors show great potential in superior energy storage devices. However, the energy density of these capacitors is still inadequate to meet the requirement of energy storage applications. In this study, the Bi_0.5Na_0.47Li_0.03TiO₃-xNaNbO₃ (BNLT-xNN) ceramics were prepared via conventional solid-phase reaction. Results showed that NN can efficaciously enhance the breakdown strength (E_b) and the relaxation behavior of the BNLT ceramic because of the broken ferroelectric long-range order. When x = 0.3, the maximum E_b reached 350 kV/cm, at which the 0.7BNLT-0.3NN ceramic exhibited the high recoverable energy storage density (W_rec) of 4.83 J/cm³ and great efficiency (η) of 78.9%. The ceramic demonstrated good temperature stability at 20 °C-160 °C and excellent fatigue resistance. Additionally, the 0.7BNLT-0.3NN ceramic presented high power density (P_D; ～77.58 MW/cm³), large current density (C_D; ～861.99 A/cm²), and quite short discharge time (t_0.9; ～0.090 μs). These results indicated that the 0.7BNLT-0.3NN material has excellent energy storage properties and various application prospects.     

Highly efficient full-fluorescence organic light-emitting diodes with exciplex cohosts

Full-fluorescence organic light-emitting diodes (FOLEDs) with low cost and high efficiency are imperious demands for commercial process in flat panel display and lighting products. We fabricated a series of FOLEDs employing C545T and DCJTB as doped dyes and different exciplex blends as cohosts. The results proved that reverse intersystem crossing (RISC) efficiency of exciplex cohost has a significant effect on the device performance. Devices with TAPC:PIM-TRZ as cohost which possessed the highest RISC efficiency showed the best results. The green FOLEDs exhibited the maximum external quantum efficiencies (EQEs) approaching to 20%, the red FOLEDs exhibited EQEs over 10% and all the EQE roll-offs are less than 10% at 1000 cd m⁻², which are among the best reported results so far, suggesting these exciplex cohosts are promising for FOLEDs.     

Combating Biofilm Associated Infection In Vivo: Integration of Quorum Sensing Inhibition and Photodynamic Treatment based on Multidrug Delivered Hollow Carbon Nitride Sphere

Recently, quorum sensing (QS) inhibitors (QSIs) have been combined with antibiotics to enhance antibiofilm efficacy in vitro and in vivo. However, targeting QS signals alone is not enough to prevent bacterial infections. Drug resistance and recurrence of biofilms makes it difficult to eradicate. Herein, photodynamic therapy (PDT) is selected to unite QSIs and antibiotics. A synergistically antibiofilm system, which combines QSIs, antibiotics, and PDT based on hollow carbon nitride spheres (HCNSs) is envisaged. First, HCNS provides the multidrug delivering ability, enabling QSIs and antibiotics to be released in sequence. Subsequently, multistage releases sensitize bacteria effectively, potentiating the chemotherapeutic effects of the antibiotics. Finally, the integration of QSIs and PDT not only minimizes the possibility of drug resistance, but also overcomes the problem of limited mass and extension of PDT. Even after 48 h of incubation, the bacterial biofilm is obviously inhibited. And its biofilm disperse efficiency exceeds 48% (compared with QSI‐potentiated chemotherapy group) and 40% (compared with PDT group). Besides, the inhibition of the QS system influences phenotypes related to virulence factor production and surface hydrophobicity, which weaken biofilm invasion and formation. Eventually, this system is applied to disperse bacterial biofilm in vivo. Overall, PDT and QS modulation are devoted to eradicate drug resistance and recurrence of the biofilm.     

A critical review of diamond like carbon coating for wear resistance applications

In recent years innovation in carbon based materials have encouraged both researchers as well as industrialists to develop materials/composites with improved tribological properties. Researchers have been fascinated to develop diamond like carbon (DLC) or carbon nanotubes (CNTs) reinforced coatings to their good corrosion resistance, excellent wear resistance, good adhesion strength, and self -lubricious nature. The present review article is mainly focused on various techniques employed in order to process DLC/CNTs coatings as well as provide a summary of DLC/CNTs deposition on different substrates. The present study includes major types, properties and tribological behavior of carbon based materials and mechanisms involved in coating deposition. The study also discusses that deposition of DLC/CNTs coatings on the substrate materials enhances the wear, corrosion and mechanical properties of the substrate.     

基于改进粗糙集理论的SAR图像目标增强

图像增强在提高SAR图像舰船目标检测精度方面具有十分重要的意义。由于传统算法不能很好地对SAR图像进行目标增强，提出了基于改进粗糙集理论和引力场强度的目标增强算法。通过借鉴引力场相关理论知识，将粗糙集条件属性集中的梯度属性改进为引力场强度属性，从而实现对原图像的目标增强。与其他算法进行了实验比较，结果表明提出的改进算法相比于其他算法更适用于SAR图像特性，能更好地对舰船目标像素进行针对性增强，具备一定的工程应用价值。     

图像分类中基于分类矢量量化的视觉词袋模型

特征表示是图像识别和分类的基础，视觉词袋是一种图像的特征表示方法。分析现有视觉词典构建方法的不足，提出一种新的视觉词典构建方法。首先利用梯度方差把特征矢量分为光滑类和边缘类，然后分别针对不同类别的特征矢量进行视觉词典的构建，最后根据两类视觉词典生成视觉词袋。图像分类实验表明，提出的新方法能提高分类准确率。     

在轨维修后端模块接口机构的研究

在轨维修可以大大的延长空间科学仪器的使用寿命,节省大量的经济成本。为了实现空间望远镜后端模块的在轨操作和更换,设计了一套与之对应的接口机构,能够解决在轨快速定位与安装。根据321运动学定位准则,详细介绍了该接口机构的内部组成和工作原理;然后把该接口机构与后端模块进行组件级有限元仿真,仿真结果表明一阶模态远高于整机基频可以有效地避免发射时候的共振;设计了一套平面内的工装来模拟后端模块,利用等效质量法对整个机构进行重力卸载;搭建实验平台,利用激光跟踪仪来测量整个后端模块的重复定位安装精度,实验数据表明,X,Y,Z 3个方向的重复平移定位误差分别为±5.58μm,±3.24μm及±3.63μm,优于总体指标±10μm;热实验结果表明整个机构可以完全释放由于温度变化产生的形变,具有很高的热稳定性;使入射光线和靶面的相对位置持续稳定,保证了较高的成像质量。为其他空间在轨维护装置提供强有力的参考价值。     

Sensitivity of positrons at hydrogen storage sites in FeCr alloy containing vacancy and helium atom

Here, the storage sites of hydrogen in FeCr alloy, namely (H, He)–V nano-clusters with open volume, have been investigated by first-principles calculations and positron annihilation spectroscopy. The positron lifetimes in the nano-clusters obtained by theoretical calculations and experiments were compared. These results suggest that positron is sensitive to the relative position of the gas atoms decorating the open volume; and a helium atom forms a more repulsive ion core than a hydrogen atom when it occupies the vacancy, resulting in a decrease in positron lifetime. Interpretation of the PAS data was successfully combined with theoretical calculations, and allowed us to determine the defect status in specimens after H/He irradiation with different implantation patterns. The speculated kinds of hydrogen storage sites formed after irradiation are summarized. For the He-ions pre-implanted situation, the helium-vacancy clusters or bubbles forming in advance may recombine with H atoms to form stable He–H–V complex.     

Development of mobile miniature natural gas liquefiers

With increasing consumption of natural gas (NG), small NG reservoirs, such as coalbed methane and oil field associated gas, have recently drawn significant attention. Owing to their special characteristics (e.g., scattered distribution and small output), small-scale NG liquefiers are highly required. Similarly, the mixed refrigerant cycle (MRC) is suitable for small-scale liquefaction systems due to its moderate complexity and power consumption. In consideration of the above, this paper reviews the development of mobile miniature NG liquefiers in Technical Institute of Physics and Chemistry (TIPC), China. To effectively liquefy the scattered NG and overcome the drawbacks of existing technologies, three main improvements, i.e., low-pressure MRC process driven by oil-lubricated screw compressor, compact cold box with the new designed heat exchangers, and standardized equipment manufacturing and integrated process technology have been made. The development pattern of “rapid cluster application and flexible liquefaction center” has been eventually proposed. The small-scale NG liquefier developed by TIPC has reached a minimum liquefaction power consumption of about 0.35 kW·h/Nm³. It is suitable to exploit small remote gas reserves which can also be used in boil-off gas reliquefaction and distributed peak-shaving of pipe networks.