气相色谱法测定焦油中微量苯稠杂环化合物

利用蒸馏分离—气相色谱法技术,建立了同时测定煤焦油中苊、氧芴和芴的分析方法。通过对色谱条件的优化,以甲苯为溶剂,正十二烷为内标物,将煤焦油馏分采用DB-5毛细管柱,对煤焦油中苊、氧芴和芴定量分析。分析结果表明:3种主要成分线性关系良好,相关系数均大于0.9995,加标回收率为95.4%~102.4%,相对标准偏差为2.89%~7.14%。该方法分离效果好,检测结果准确、可靠。     

Anthocyanin-fortified konjac glucomannan/sodium alginate composite edible boba: characteristics of texture,microstructure, in vitro release behaviour and antioxidant capacity

Konjac glucomannan/sodium alginate composite edible boba (KGM/SA-boba) with good taste is very popular in China, and it is an outstanding carrier for health potential ingredients. In this work, KGM/SA-boba were fortified with 0.25, 0.50, 0.75 and 1.00% purple sweet potato anthocyanin (PSPA), then characterised by the water distribution, texture, microstructure, in vitro release property of PSPA and antioxidant capacity. LF-NMR analysis demonstrated that the free water of KGM/SA-boba could transfer to tightly bound water with the addition of PSPA that made it with better water-binding ability, higher springiness and lower hardness. And the results of SEM and rheology showed that PSPA could stabilise the microstructure of KGM/SA-boba by forming more amorphous regions and hydrogen bonds proved by the results of DSC and FT-IR. Furthermore, 50% of PSPA in PSPA-fortified KGM/SA-boba can be released at the first hour in a simulated gastrointestinal environment. And the scavenging capacity of DPPH and ABTS of the PSPA-fortified KGM/SA-boba after digestion was higher than that of PSPA alone. Generally, PSPA could improve the texture while KGM/SA-boba in turn would make PSPA more stable in the gastrointestinal digestive system.     

Hierarchical porous transition metal oxide nanosheets templated from waste bagasse: General synthesis and Li/Na storage performance

As a promising anode candidate, hierarchical porous transition metal oxide nanosheets (TMO-NSs) have attracted significant interest due to their various advantages of abundant active sites, high specific capacity and shortened ion/electrons transport pathways. Although the TMO-NSs have been developed in the past decades, the previous synthesis strategies have some drawbacks such as high cost, complex synthesis techniques, and the requirement of special instruments. Herein, we develop a generalized and facile biomorphic method to synthesize various controllable hierarchical porous TMO-NSs by using waste bagasse as biotemplate. Furthermore, the porosity and pore size of as-prepared hierarchical porous TMO-NSs can be adjusted by changing the precursor solution concentration. Novel hierarchical porous TMO-NSs have been successfully prepared for many ternary or binary TMO, such as NiFe₂O₄, ZnFe₂O₄, ZnMn₂O₄, NiO and ZnO. Owing to their unique nanostructure, as-synthesized hierarchical porous TMO-NSs show an excellent electrochemical performance when used as anode for Li/Na-ion batteries. We believe that various hierarchical porous TMO-NSs available from the green, economical and convenient biomorphic strategy may lead to further developments in research and application on TMO-NSs materials.     

Synthesis and performance evaluation of a new drag reducer based on acrylamide/12-allyloxydodecyl acid sodium

Hydraulic fracturing with slickwater is a field-proven stimulation technology used in tight reservoirs. Because of the high pumping rate associated with slickwater fracturing, drag reduction (DR) is critical in minimizing pressure drop and the success of oilfield operations. In this paper, a new type of drag reducer (SPR) was synthesized with acrylamide and 12-allyloxydodecyl acid sodium, and its drag reduction performance was evaluated. The results showed that the new drag reducer features low molecular weight, fast-dissolving rate and low interfacial tension. The algorithm of estimating the drag reduction rate of non-Newtonian fluid SPR was proposed and validated. Empirical or semianalytical models for estimating the friction ratio (σ) or friction factor (λ or f) were used to simulate the turbulence behavior of the SPR drag reducer under different Reynolds numbers (Re). The modified Virk's correlation could accurately model the turbulent behavior of the SPR drag reducer. A unified calculation formula was established in this study for different pipe diameters.     

Structural Aspects of P2-Type Na0.67Mn0.6Ni0.2Li0.2O2 (MNL) Stabilization by Lithium Defects as a Cathode Material for Sodium-Ion Batteries

A known strategy for improving the properties of layered oxide electrodes in sodium-ion batteries is the partial substitution of transition metals by Li. Herein, the role of Li as a defect and its impact on sodium storage in P2-Na_0.67Mn_0.6Ni_0.2Li_0.2O₂ is discussed. In tandem with electrochemical studies, the electronic and atomic structure are studied using solid-state NMR, operando XRD, and density functional theory (DFT). For the as-synthesized material, Li is located in comparable amounts within the sodium and the transition metal oxide (TMO) layers. Desodiation leads to a redistribution of Li ions within the crystal lattice. During charging, Li ions from the Na layer first migrate to the TMO layer before reversing their course at low Na contents. There is little change in the lattice parameters during charging/discharging, indicating stabilization of the P2 structure. This leads to a solid-solution type storage mechanism (sloping voltage profile) and hence excellent cycle life with a capacity of 110 mAh g^-1 after 100 cycles. In contrast, the Li-free compositions Na_0.67Mn_0.6Ni_0.4O₂ and Na_0.67Mn_0.8Ni_0.2O₂ show phase transitions and a stair-case voltage profile. The capacity is found to originate from mainly Ni³⁺/Ni⁴⁺ and O^2-/O^2-δ redox processes by DFT, although a small contribution from Mn⁴⁺/Mn⁵⁺ to the capacity cannot be excluded.     

海藻酸钠/脲醛树脂复合微胶囊的缓释动力学特性

采用两步法制备海藻酸钠/脲醛树脂复合微胶囊。在树脂化阶段引入海藻酸钠(SA)参与脲醛树脂(UF)的缩聚反应形成复合壳层,制备了阿维菌素复合微胶囊。通过FTIR、TG、SEM、粒度分析等表征微胶囊的结构特征、组成成分、表观形貌、粒度分布。结果表明,SA的引入可有效改善脲醛树脂微胶囊的团聚现象,提高药物的包覆率至60%以上。释放性能研究显示,复合微胶囊的缓释能力较脲醛树脂微胶囊提高,72 d累计释放率由27.5%增至44.5%,且释放速率受pH、温度的影响,25℃下酸性介质中27d累计释放率超过50%。释放行为均可用Korsmeyer-Pappas动力学模型进行描述。     

聚苯乙烯磺酸钠掺杂正渗透膜的制备及其性能

通过两步无皂乳液聚合法，改变第二步对苯乙烯磺酸钠的加入量，制备表面携带磺酸根基团量不同的纳米粒子（PSS），并将其应用于正渗透（FO）膜的制备。采用红外光谱仪（FTIR）和光电子能谱仪（XPS）表征粒子组成，通过扫描电子显微镜（SEM）表征膜的表面和断面形貌，测定膜孔隙率和亲水性，考察表面磺酸根量不同的聚合物粒子对膜结构性能的影响。结果表明，PSS的引入能提高膜的孔隙率，改善膜的亲水性，且随着粒子表面携带的磺酸根基团量增多，膜的孔隙率与亲水性也随之提高。这是因为PSS粒子可以支撑内部孔道，且表面携带的亲水基团-SO3Na可以提高膜的亲水性，影响活性层的形成。所制备的FO膜性能也得到相应改善，水通量达到了61.1L/(m²·h)，为纯聚砜膜的2.8倍，盐截留率达到93.2%，J_s/J_v值仅为0.31g/L，性能得到极大提升。     

海藻酸钠/壳聚糖微囊的研究进展

海藻酸钠(sodium alginate,SA)是从褐藻或海藻中提取出来的聚阴离子电解质;壳聚糖(chitosan,CS)是通过甲壳素脱乙酰化获得的聚阳离子电解质。这两种物质都具有优异的生物相容性、良好的生物可降解性、抗菌性和伤口愈合活性。介绍了海藻酸钠/壳聚糖微囊的生物特性,制备方法及其在医学领域中的应用,并对其应用前景进行展望。     

十二烷基硫酸钠修饰NiFe2O4对亚甲基蓝的类芬顿催化氧化性能

采用化学沉淀法制备了十二烷基硫酸钠（SDS）改性的纳米酸镍（记为NiFe₂O₄-S），利用X射线衍射（XRD）、红外光谱（FTIR）、能谱（EDS）、透射电镜（TEM）、BET比表面等技术手段对样品进行了表征。采用多相芬顿氧化技术，以亚甲基蓝溶液为模拟污染物废水，研究了SDS对铁酸镍的改性效果、亚甲基蓝溶液初始pH以及催化剂循环使用等不同条件因素对样品类芬顿催化活性的影响。结果显示，经SDS改性后的NiFe₂O₄-S比纯相NiFe₂O₄表现出了更优异的催化性能，NiFe₂O₄-S对酸性（pH=3.5）、近中性（pH=6.5）和碱性（pH=9.5）的亚甲基蓝溶液均有着较好的催化降解效果；NiFe₂O₄-S具有良好的催化稳定性和重复使用性。对该催化反应体系的作用机理进行了详细探讨，NiFe₂O₄-S表现出优异的类芬顿催化活性归因于更强的电子转移能力，吸附的SDS能促进H₂O₂和 \text{?} {\mathrm{O}}_{\mathrm{2}}^{\text{-}} 分别与表面Fe³⁺反应将其还原转化为Fe²⁺。·OH是直接分解亚甲基蓝的活性物种，反应中NiFe₂O₄-S表面较高浓度的Fe²⁺可以有效地把H₂O₂分解为·OH。SDS增强了催化剂表面对亚甲基蓝的吸附能力，促进了·OH与亚甲基蓝的分解反应。     

离子色谱-电导法检测酱油中氯化钠的含量

该研究采用灰化预处理+离子色谱-电导法检测酱油中食盐的含量，并与莫尔法、电位滴定法进行比较。结果表明，莫尔法存在滴定过量问题，电位滴定法对温度等外界环境条件和仪器操作要求苛刻，而离子色谱-电导法具有操作简便快速并具有较好的准确度和精密度。实验结果表明，氯化钠含量处于11.56～11.61 g/100 mL之间，回收率实验结果为96.00%～102.10%，相对标准偏差为0.089%。干扰实验对结果无明显影响，且能同时测定多种离子，可用于成品酱油中氯化钠含量的检验。