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.     

卫生纸机压榨部运行参数及能效关系分析与优化

通过对纸机压榨部压力和压榨脱水原理的分析，得到出压榨部纸幅干度可作为压榨部的能耗指标，同时确定压榨线压力和纸机车速是压榨部能耗的主要影响因素。结合纸机实际生产测试并记录压榨脱水数据，绘制测试数据曲线图并拟合压榨线压力、纸机车速和出压榨部纸幅干度三者之间的函数关系，最终确定压榨线压力和纸机车速的最优取值范围。通过对测试数据的分析和拟合，控制压榨线压力在90 kN/m、纸机车速在1075 m/min时，纸幅质量可满足正常生产的要求，还可以节约2.1%的电能，实现卫生纸机压榨部的能耗优化。     

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.     

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。     

2014～2018年福建省生产领域卫生纸卫生质量分析

对福建省生产领域近五年的卫生纸进行随机抽样和质量分析,分别检测了产品的细菌菌落总数、大肠菌群、金黄色葡萄球菌、溶血链球菌。结果显示:卫生纸生产企业主要集中在福州、漳州、泉州三个地市,企业共占比64.4%;大肠菌群、金黄色葡萄球菌、溶血性链球菌均未检出,细菌菌落总数共5批次不合格,卫生指标合格率为97.7%;合格产品卫生性能逐年提升,呈现较高质量水平,细菌菌落总数检出率2014年为74.5%,近四年在39.5%~60.0%之间,呈现下降的趋势;细菌菌落总数统计均值,由60.8CFU/g下降至15CFU/g左右,从国标最高限值的10.1%下降到2.5%左右;按地域统计,不合格产品主要分布在福州地区;泉州、三明、厦门三地市生产的卫生纸合格产品质量较高,细菌菌落总数均值分别为14.7CFU/g、16.8CFU/g、12.6CFU/g,分别为国标最高限值的2.5%、2.8%、2.1%。按产品质量等级统计,在所有产品中,卫生纸合格品、一等品、优等品质量等级产品的卫生合格率分别为97.53%、96.97%、100%。