The First Introduction of Graphene to Rechargeable Li–CO2 Batteries

The utilization of the greenhouse gas CO₂ in energy‐storage systems is highly desirable. It is now shown that the introduction of graphene as a cathode material significantly improves the performance of Li–CO₂ batteries. Such batteries display a superior discharge capacity and enhanced cycle stability. Therefore, graphene can act as an efficient cathode in Li–CO₂ batteries, and it provides a novel approach for simultaneously capturing CO₂ and storing energy.     

Controllable Growth of Perovskite Films by Room‐Temperature Air Exposure for Efficient Planar Heterojunction Photovoltaic Cells

A two‐step solution processing approach has been established to grow void‐free perovskite films for low‐cost high‐performance planar heterojunction photovoltaic devices. A high‐temperature thermal annealing treatment was applied to drive the diffusion of CH₃NH₃I precursor molecules into a compact PbI₂ layer to form perovskite films. However, thermal annealing for extended periods led to degraded device performance owing to the defects generated by decomposition of perovskite into PbI₂. A controllable layer‐by‐layer spin‐coating method was used to grow “bilayer” CH₃NH₃I/PbI₂ films, and then drive the interdiffusion between PbI₂ and CH₃NH₃I layers by a simple air exposure at room temperature for making well‐oriented, highly crystalline perovskite films without thermal annealing. This high degree of crystallinity resulted in a carrier diffusion length of ca. 800 nm and a high device efficiency of 15.6 %, which is comparable to values reported for thermally annealed perovskite films.     

大气环境下合成白光发射的Tb3+/Eu3+共掺杂全无机卤化物钙钛矿量子点

为克服因混合不同卤化物钙钛矿量子点发生阴离子交换反应、不稳定的红光发射卤化物钙钛矿量子点等而导致在获取白光发射方面存在的不足,提出了一种可以在大气环境下合成Tb³⁺,Eu³⁺稀土离子共掺杂全无机卤化物钙钛矿量子点的方法。调节Tb³⁺,Eu³⁺稀土离子的掺杂比例,调控从钙钛矿量子点主晶格到Tb³⁺和Eu³⁺离子的能量转移,获得了单一组分、白光发射的钙钛矿量子点(Tb,Eu):CsPbCl3和(Tb,Eu):CsPb(Cl/Br)3,并对量子点的形貌、结构、发光性能及能量传递机理和稳定性进行了详细研究。研究结果表明:在365nm激光激发下,不同含量Tb³⁺/Eu³⁺离子共掺杂的钙钛矿量子点(Tb,Eu):CsPbCl3发射光谱对应的色坐标位于1931色度图中的白光区域。在进料比PbCl2∶TbCl3∶EuCl3为1∶1.5∶1时,量子产率为3.59%,比纯的CsPbCl3量子点的量子产率(0.57%)提高了6倍。进一步研究发现,该(Tb,Eu):CsPbCl3量子点在空气中储存2个月之后,量子产率几乎保持不变(3.63%),保持了良好的稳定性。此外,研究了采用不同溶剂(正辛烷、十八烯)合成Tb³⁺/Eu³⁺共掺杂钙钛矿量子点的发光特性。Tb³⁺/Eu³⁺离子共掺杂的钙钛矿量子点(Tb,Eu):CsPbCl3可实现单一组分的白光发射,有良好的稳定性,具备一定的应用前景。     

Numerical study on effects of check valve closure flow conditions on pressure surges in pumping station with air entrainment

This paper proposes a numerical procedure to better compute the characteristics of pressure surges when check valves close under different flow conditions in a pumping station. Studies have shown that the effects of check valve closure on the pressure transients are predominantly dependent on the magnitude and gradient of the flow velocities immediately downstream of the check valve at the instant of valve closure. Through the present study, it was noted that the transient flow velocities near the check valve of a fluid system are also dependent on the characteristics of the air entrained into the fluid system. An improved numerical computational procedure for the fluid system with air entrainment under different transient conditions downstream of the check valve is also proposed in this paper. With a fluid system operating within the critical range of air entrainment values, the present analysis showed that there is a possibility of ‘high pressure surges’ when the check valves were closed at flow rates other than the positive flow conditions. This phenomenon was confirmed through field observations. This study thus concludes that a detailed numerical transient analysis of the fluid system, with various assumed amounts of entrained air, is necessary whenever there is the possibility of air entrainment into the fluid system, and that the flow conditions at the instant of check valve closure need to be modelled. Copyright © 2001 John Wiley & Sons, Ltd.     

一次引爆的固态燃料空气炸药爆炸特性的研究

本文研究了一次引爆的固态燃料空气炸药的爆炸特性，实验给出了爆炸超压与燃料质量、距离的关系曲线，并与TNT进行了对比，同时根据爆炸相似率，得到了计算爆炸超压的拟合方程，其计算结果与实验值的相对误差绝对值小于10％。     

Surface modification of thin polystyrene films

 The sulfonation of polystyrene (PS) films with 50 and 96% sulfuric acid as a function of time is presented. In contrast to previous literature reports, we showed that the treatment of PS films even with dilute sulfuric acid yields sulfonated surfaces after reaction times of 30 s–1 h. The hydrophilicity of the modified PS increased considerably in comparison to the unreacted PS films. X-ray photoelectron spectroscopy yielded evidence for the sulfonation of PS at the surface. Unreacted spin-coated PS films were very smooth, while modified PS showed some clumps dispersed on a flat surface, as analyzed by atomic force microscopy. The surface morphology was identified as a phase-separated system composed of domains of unreacted PS and a matrix of sulfonated PS by fluorescence microscopy using the positively charged dye rhodamine B. The adsorption of the polycation diallyldimethylammonium chloride on the sulfonated PS surface could be detected. The thickness of the adsorbed polycation was 2.2 nm. Received: 3 November 1998 Accepted in revised form: 23 February 1999     

Evaluation of gas chromatography coupled with ion mobility spectrometry for monitoring vinyl chloride and other chlorinated and aromatic compounds in air samples

The objective of this research was to evaluate, in the laboratory, the potential of gas chromatography/ion mobility spectrometry (GC/IMS) for monitoring vinyl chloride and other organic compounds in air samples in the field. It was determined that GC/IMS has the potential to directly detect vinyl chloride in air at the 2 ppbv level, and when concentrated on an adsorbent trap from a 1 L sample of air, detection could be lowered to the 0.02 ppbv level. From a comparative investigation of 18 EPA priority pollutants and 34 common vapor-phase organic compounds, many compounds were found to provide a more sensitive response in IMS than vinyl chloride, indicating that GC/IMS would be broadly applicable to the direct detection of vapor-phase organics in air. Operating parameters including drift gas, spectrometer temperature, and sample-inlet position were evaluated and discussed with respect to sensitivity and resolution. High temperature dramatically increased sensitivity to vinyl chloride. Vinyl chloride was shown to produce both negative and positive ion mobility spectra, with the negative-mode spectra resulting from electron-capture dissociation of the vinyl chloride. The limit of detection for vinyl chloride was found to be 7 pg/s. Limits of detection for 18 EPA priority pollutants were determined and compared to vinyl chloride. The responses of 34 other vapor-phase organic compounds were also compared to that of vinyl chloride. Non-selective, positive-ion detection of 30 of the 34 compounds was demonstrated along with selective, electron-capture-type detection of 29 of them. Chloride-specific and bromide-specific detection illustrated the advantages of selected-ion monitoring in IMS.     

某小型空调器的设计思考

介绍了某小型空调器的设计思路,主要从结构的紧凑性、制冷系统的匹配、高空工作的适应性、加热器的确定及可靠性等方面给予了阐述,同时与国外同类型空调器进行了对比,通过实际应用说明了其设计的可行性。     

一种玻璃微流控芯片的实用制作工艺研究

本文提出了一种在商品化的SG4009玻璃上制作50×50 mm微流控芯片的方法。SG4009玻璃表面有厚度570 nm的光刻胶S-1085和厚度145 nm的Cr层组成的掩蔽层,省去制作掩蔽层的时间和设备,降低了生产成本,缩短了生产周期。对芯片制作过程中的一些问题进行分析研究,提出相应的解决方案,保证了芯片的制作质量。