基于MF-DCCA 的呼吸道疾病与大气污染物相关性分析

针对呼吸道系统疾病与大气 PM2:5、 SO2 浓度序列的相关性特征, 应用多重分形消除趋势波动分析法 (MF-DCCA), 对张家界市永定区呼吸道系统疾病患病人数与大气 PM2:5、 SO2 浓度序列进行了研究。结果发现该地区 呼吸道系统疾病患病人数与大气 PM2:5、 SO2 浓度的相关性具有长期持续特征和多重分形特征。随后对它们相关性 多重分形特征的动力来源进行了分析, 通过随机重排和相位随机处理, 结果表明在不同时间尺度上的长期持续性影响 是其主要动力来源。进一步研究发现该地区呼吸道系统疾病与大气 PM2:5、 SO2 浓度序列的相关性在四个季节均具 有长期持续性的多重分形特征, 且夏季多重分形特征相对强于其他季节。     

Stable Radicals with Protective Umbrellas Integrated on the Surface of 2D Layered Materials

Radicals are closely related to human life and health and have been widely used in biology, chemistry, functional materials, etc. However, the high reactivity, disorder, and short half-lives limit their wide applications. Therefore, it remains a great challenge to prepare stable and ordered radicals. Herein, radicals are prepared with protective umbrellas (diethylmethyleneamine, DEMA) that are integrated on the surface of 2D layered materials to isolate water and oxygen and enhance the stability of radicals. Taking 2D black phosphorus (BP) as an example: triethylamine reacts with dichloromethane to form quaternary ammonium salts with further Hoffmann elimination to produce DEMA radicals that could react with one electron of a lone pair electrons in P on the surface of BP to produce P radicals, which shows a prolonged half-life of 21 days at room temperature. First-principle calculations and electron paramagnetic resonance fitting confirm that the steric hindrance constructed by dense DEMA passivation layer acts as a protective umbrella and the 2D coupling of P radicals and other P atoms in 2D BP plane to enhance the stability and strong superexchange interaction of P radicals. Furthermore, it is a general strategy to produce stable radicals integrated on the 2D plane.     

Stabilization of natural gas foams using different surfactants at high pressure and high temperature conditions

Natural gas foam can be used for mobility control and channel blocking during natural gas injection for enhanced oil recovery, in which stable foams need to be used at high reservoir temperature, high pressure and high water salinity conditions in field applications. In this study, the performance of methane (CH₄) foams stabilized by different types of surfactants was tested using a high pressure and high temperature foam meter for surfactant screening and selection, including anionic surfactant (sodium dodecyl sulfate), non-anionic surfactant (alkyl polyglycoside), zwitterionic surfactant (dodecyl dimethyl betaine) and cationic surfactant (dodecyl trimethyl ammonium chloride), and the results show that CH₄-SDS foam has much better performance than that of the other three surfactants. The influences of gas types (CH₄, N₂, and CO₂), surfactant concentration, temperature (up to 110°C), pressure (up to 12.0 MPa), and the presence of polymers as foam stabilizer on foam performance was also evaluated using SDS surfactant. The experimental results show that the stability of CH₄ foam is better than that of CO₂ foam, while N₂ foam is the most stable, and CO₂ foam has the largest foam volume, which can be attributed to the strong interactions between CO₂ molecules with H₂O. The foaming ability and foam stability increase with the increase of the SDS concentration up to 1.0 wt% (0.035 mol/L), but a further increase of the surfactant concentration has a negative effect. The high temperature can greatly reduce the stability of CH₄-SDS foam, while the foaming ability and foam stability can be significantly enhanced at high pressure. The addition of a small amount of polyacrylamide as a foam stabilizer can significantly increase the viscosity of the bulk solution and improve the foam stability, and the higher the molecular weight of the polymer, the higher viscosity of the foam liquid film, the better foam performance.     

Application of bio-based dimer acid diglycidyl ester in paper-based copper clad laminate

Using dimer acid (DA) as raw material, DA diglycidyl ester (DADGE) was synthesized and used as reactive toughening agent to prepare paper-based copper clad laminate (p-CCL). The factors affecting the epoxy value of DADGE and the effect of the resin on the gelation time were studied. The effects of the epoxy value and the addition amount of DADGE on the solderleaching resistance, flammability, water absorption, bending strength, and impact strength of the p-CCL were discussed. The results showed when the molar ratio of DA to ECH was 1:8 and the molar ratio of DA to sodium hydroxide was 1:1.6, the epoxy value of DADGE reached the maximum value of 0.23 mol/100 g. The DADGE can shorten the gelation time of the glue. The p-CCL meets the performance of the IPC-TM-650 standard. And when the addition amount of DADGE is less than 12 wt %, the flammability of the p-CCL reaches UL94V-0 level. The p-CCL prepared by adding 6 wt % of DADGE with 0.08 mol/100 g epoxy value has the best comprehensive performance, its toughness and rigid are comparable to those of p-CCL with 12 wt % of commercially available high performance toughening agents and it has higher solderleaching resistance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47508.     

风生水起的移动电台

随着现代人工作、生活节奏不断加快,娱乐文化需求日趋多样化,优质原创内容急剧增加,同时各项信息通信技术超常发展,传统广播业被颠覆,移动电台却由此风生水起。移动电台打破了传统音频与互联网的壁垒,突破了时间和地域的限制,以其强烈的伴随性,受到越来越多人的喜爱,各种移动电台如雨后春笋般涌现。     

主成分分析研究白酒基酒香气成分

以485个优质基酒和普通基酒的主要香气成分数据为基础，采用R语言软件，分别对两类基酒进行4次随机抽样，每次抽取60个样品，基酒品质分析数据经标准化处理后进行主成分分析。结果表明，优质基酒4次抽样主成分分析结果比较稳定，普通基酒分析结果差异较大。碎石图检验表明，优质基酒在第一、二、三主成分后断崖明显，普通白酒在第一主成分后下降平缓，没有明显断崖。分布分析表明，优质基酒密度分布图的尖峰厚尾现象明显，方差为0.560，样本间的差异小，香气成分含量范围相对集中；普通基酒分布较为分散，方差为0.925，样本间差异较大，香气成分含量范围不稳定。在白酒风味分析时，应考虑样本的数据特征，以保证分析结果的准确性和可靠性，进而有效指导白酒生产。     

高果糖浆废液杂糖组分分析及其作为毕赤酵母发酵碳源的资源化利用

废杂糖的资源化利用是高果糖浆生产行业迫切需要解决的问题。该研究首先通过高效液相、质谱和红外光谱分析,确定了杂糖成分为葡萄糖、果糖和聚合度为2~16的线性葡聚糖,包括葡萄糖480 g/L,果糖92 g/L,麦芽糖103.6 g/L,麦芽三糖36.8 g/L,总糖含量802.3 g/L。进一步使用2种常用的毕赤酵母宿主(P AOX1型毕赤酵母、P GAP型毕赤酵母)利用杂糖发酵生产内切β-1,3葡聚糖酶并与标准碳源(甘油和葡萄糖)作对比。结果表明,对于P AOX1型毕赤酵母,杂糖做碳源时细胞密度和酶活性与甘油相比均有所下降,最大生物量分别为59.1和82.0 g/L,最高酶活性分别为157.29和199.2 U/mL。对于P GAP型毕赤酵母,杂糖与葡萄糖的发酵效果相当,说明杂糖可以作为P GAP型毕赤酵母生产内切β-1,3葡聚糖酶的优质替代性碳源。