基于纸喷雾离子化衍生质谱法快速检测PM2.5中的醌污染物

醌类化合物是PM2.5中的一类有害物质。本研究建立了纸喷雾离子化衍生质谱法快速测定PM2.5中的醌类污染物。通过衍生化反应在醌化合物中引入氨基，提高醌在纸喷雾中的离子化效率。随后对衍生化试剂种类、电压、喷雾溶剂种类等反应条件进行优化。在最优实验条件下，采用内标法定量分析1,4-苯醌、甲基对苯醌、1,4-萘醌和1,4-蒽醌，4种化合物均呈现较好的线性关系，其检出限分别为4.49、20.89、0.13、0.17 ng。利用该方法分析PM2.5实际样品中的萘醌和蒽醌，均获得了较好的定性和定量结果。     

One-step to prepare high-performance gas diffusion layer (GDL) with three different functional layers for proton exchange membrane fuel cells (PEMFCs)

Gas diffusion layer (GDL) is one of the most important components of fuel cells. In order to improve the fuel cell performance, GDL has developed from single layer to dual layers, and then to multiple layers. However, dual or multi layers in GDL are usually prepared by layer-by-layer methods, which cost too much time, energy, and resources. In this work, we successfully developed a facile one-step method to prepare a GDL with three functional layers by utilizing the different sedimentation rates and filtration rates of short carbon fiber (CF) and carbon nanotube (CNT). The treatment temperature for this GDL is much lower than that of traditional method. The thickness of the GDL can be effectively controlled from as thin as 50 μm to more than 200 μm by simply adjusting the content of CF. The GDL with high flexibility is suitable to develop high performance flexible electronics. The fuel cell with the GDL has the maximum power density 1021 mW cm^?2, which shows 19% improvement comparing to the conventional one. Therefore, this work breaks the traditional concept that GDL for fuel cells only can be prepared by very complex and high-cost procedure.     

Investigation of fabrication of gas diffusion substrate for proton exchange membrane fuel cells

The gas diffusion substrate (GDS) is essential in the proton exchange membrane fuel cells. Its fabrication techniques affect the performance significantly and are worthy of investigation. In this study, a manufacturing process of the GDS is proposed to understand the formation process of GDS and promote its structure and performance more pertinently. Different states during the preparation process, raw carbon paper, pre-curing, curing, carbonation, and graphitization, are characterized and measured. Experimental and numerical methods are employed to determine the relationships between microstructure, transport, and mechanical performance variation with the fabricating processes. The results show that its porosity, average pore size, and effective diffusivity decrease first and increase after curing. These parameters after graphitization are lower than that of the carbon paper (CP). The electrical resistivity increases dramatically while pre-curing and decreases gradually after curing, carbonation, and graphitization, and it is much reduced after graphitization. Moreover, mechanical measurement results show that both the picks of tensile strength and flexural modulus occur after curing. Its tensile strength shows little change after graphitization compared to the initial paper's. In contrast, the flexural modulus is improved significantly.     

科研管理项目管理系统设计与开发

信息化时代推动了我国科研水平飞速增长,为各行业、各领域提供先进的技术与设备支持,以此提升我国整体的GDP水平。文章认为在提升科研水平的过程中,科研项目管理系统起到举足轻重的作用,为科研活动的规范性、合理性与可行性提供了参考标准。     

Moulded pulp products manufacturing with thermoforming

For an effective optimization of pulp thermoforming and of the moulded pulp products manufactured by this process, a full understanding of the process physics combined with full knowledge of the pressing equipment is necessary. For this reason, in this Addendum, we clarify how the process parameters “Holding time,” “Vacuum time,” “Cycle time,” and “Temperature” were interpreted and subsequently defined for the analysis of the process and product‐related outputs of the thermoforming experiments.     

中国石油工业上游发展面临的挑战与未来科技攻关方向

石油和天然气是全球和中国最重要的一次能源。石油工业的生存发展是由油气资源、市场、技术和社会政治经济环境等要素决定的，其中，技术进步是最活跃和最关键的因素之一。中国已成为全球油气生产消费大国，中国石油工业上游的发展也高度依赖石油科技的进步。中国石油工业已形成了先进完整的理论技术研发和装备制造体系，支撑了油气产量持续稳产和增产。未来是中国社会经济发展的关键期，石油工业必将面对重大挑战与新的技术需求，大力实施国家创新战略，发展具有国际领先水平的新一代勘探开发理论技术，支撑油气产业发展，保障国家油气能源安全。中国石油工业上游在未来面临的重大挑战与技术需求包括：①满足中国未来现代化建设的巨大油气需求和保障油气供应安全，这当中必须加大中国油气勘探开发，同时进一步扩大全球及"一带一路"油气投资与生产；②实现中国石油长期稳产2×10⁸t/a以上；③实现中国天然气产量上升至3 000×10⁸m³/a并长期稳产；④发展海洋及深水油气勘探开发先进技术与装备；⑤形成新一代石油工程服务技术装备和数字化转型。中国石油工业上游未来的科技攻关方向和研发重点包括：①先进的石油大幅度提高采收率技术；②大气田勘探与复杂气田提高采收率技术；③非常规油气勘探开发技术；④海洋及深水油气勘探开发技术及装备；⑤"一带一路"油气勘探开发技术；⑥新一代石油工程服务技术装备和数字化转型。     

On the capacity of the state‐dependent interference relay channel

This paper considers the state‐dependent interference relay channel (SIRC) in which one of the two users may operate as a secondary user and the relay has a noncausal access to the signals from both users. For discrete memoryless SIRC, we first establish the achievable rate region by carefully merging Han‐Kobayashi rate splitting encoding technique, superposition encoding, and Gelfand‐Pinsker encoding technique. Then, based on the achievable rate region that we derive, the capacity of the SIRC is established in many different scenarios including (a) the weak interference regime, (b) the strong interference regime, and (c) the very strong interference regime. This means that our capacity results contain all available known results in the literature. Next, the achievable rate region and the associated capacity results are also evaluated in the case of additive Gaussian noise. Additionally, many numerical examples are investigated to show the value of our theoretical derivations.     

总变差模型在书画打印宣纸印刷质量预测中的应用

为了建立适用于书画打印宣纸印刷质量的预测模型,本研究测量了14种书画打印宣纸的粗糙度、白度、不透明度、定量、光泽度和针对宣纸特别设定的帘纹深浅以及帘纹疏密度等表面物理参量,并在相同条件下,使用喷墨打印设备输出并测量印品色度值,利用总变差模型构建去除帘纹色差的测定方法,得到与人眼视觉特征相符的色差。运用GRNN广义回归神经网络结合书画打印宣纸表面物理参量与宣纸去帘纹后的色差值,建立预测模型。结果表明,该模型能够在仅测量书画打印宣纸表面物理参量的情况下,便能较为准确地预测书画打印宣纸印刷质量,为书画打印宣纸印刷前的选纸工作提供指导依据。     

平板计数法与纸片法检测食品微生物菌落总数的比较研究

目的找出平板倾注法与纸片法2种检测食品菌落总数方法之间的相关性,判断2种方法有无显著性差异。方法样品处理按GB 4789.2-2016《食品安全国家标准食品微生物学检验菌落总数测定》进行处理,平板倾注法取样品稀释液接种平皿倾注琼脂、纸片法取样品稀释液接种细菌计数纸片。用上述2种方法对市场上随机抽取30份饼干及糕点和2份质控样品进行菌落总数检测,最后做统计学分析(t-test)。结果倾注法与纸片法检测结果无显著差异(P0.05)且对不同菌落数区间(0～100CFU/g、100～1000CFU/g、1000～10000 CFU/g)都适用。2份质控样品评价结果为满意。结论纸片法可用于食品菌落总数的快速检测,缩短检测流程,提高工作效率。     

抑菌纸对吐司保鲜作用

研究了抑菌纸对吐司保鲜作用的影响。将抑菌纸与PP薄薄膜结合得到纸塑复合材料来包装吐司，与单一的PP薄膜包装以及未采取包装的吐司对比质构、色差、水分活度、菌落总数、热焓值的差异。结果表明：采用纸塑复合材料包装的吐司相较于仅用PP薄膜包装以及未采取包装的吐司，其质构特性和色差的劣变变缓，水分活度有一定程度降低，菌落总数的增长得到有效抑制，热焓值的上升也得到延缓。该抑菌纸与PP薄膜结合得到的复合材料可避免直接向食品中添加防腐剂，并且能有效延长吐司的货架期。