Continuous Porous Aromatic Framework Membranes with Modifiable Sites for Optimized Gas Separation

Continuous microporous membranes are widely studied for gas separation, due to their low energy premium and strong molecular specificity. Porous aromatic frameworks (PAFs) with their exceptional stability and structural flexibility are suited to a wide range of separations. Main-stream PAF-based membranes are usually prepared with polymeric matrices, but their discrete entities and boundary defects weaken their selectivity and permeability. The synthesis of continuous PAF membranes is still a major challenge because PAFs are insoluble. Herein, we successfully synthesized a continuous PAF membrane for gas separation. Both pore size and chemistry of the PAF membrane were modified by ion-exchange, resulting in good selectivity and permeance for the gas mixtures H₂/N₂ and CO₂/N₂. The membrane with Br^? as a counter ion in the framework exhibited a H₂/N₂ selectivity of 72.7 with a H₂ permeance of 51844 gas permeation units (GPU). When the counter ions were replaced by BF₄^?, the membrane showed a CO₂ permeance of 23058 GPU, and an optimized CO₂/N₂ selectivity of 60.0. Our results show that continuous PAF membranes with modifiable pores are promising for various gas separation situations.     

综合性化学实验的线上线下混合式教学——以水泥分析为例

水泥熟料分析是一个经典的综合性实验,涉及重量分析和配位滴定分析的很多原理及操作。为了有效开展实验教学、缩短课堂讲解时间、客观评价学生实验数据及结果,我们开展了线上线下混合式教学,引导学生课前自主学习,训练学生综合和创新实验技能。这一改革提高了实验教学质量,取得了较好的教学效果。     

Fabrication and characterization of glutathione-responsive nanoparticles from the disulfide bond-bridged block copolymer

The purpose of this paper is to fabricate novel nanoparticles (NPs) from a single disulfide bond-bridged block copolymer poly(hydroxyethyl methacrylate)-S-S-polycaprolactone (PHEMA-S-S-PCL). The novel biomaterial was synthesized by ring-opening polymerization and reversible addition–fragmentation chain transfer polymerization. The cargo-free NPs were fabricated with the solvent evaporation method, and studies on NPs' characterizations were carried out. The hydrogen nuclear magnetic resonance (¹H NMR) and Fourier transform infrared spectroscopy spectra confirmed the synthesis of PHEMA-S-S-PCL copolymer. Thermo-gravimetric analysis curves indicated that the obtained PHEMA-S-S-PCL copolymer had good thermostability. Transmission electron microscopy and dynamic light scatter results suggested that the cargo-free NPs were in round shapes with an average diameter of 103.6 ± 0.12 nm. The low critical micelle concentration of cargo-free NPs (7.9 × 10^?4 mg/ml) indicated that these NPs would keep their spherical shapes after being attenuated by abundant liquid (e.g., blood or body fluid). Furthermore, these NPs showed high stability at the presence of bovine serum albumin. Therefore, it could be speculated that these NPs would not be absorbed by proteins in blood, and they could be used as a candidate carrier for drug delivery.     

Nonenzymatic Electrochemical Sensor for Wearable Interstitial Fluid Glucose Monitoring

We report on a nonenzymatic electrochemical sensor for wearable glucose monitoring in interstitial fluid. The sensor exhibited acceptable selectivity and reliability for continuous glucose detection for up to 30 days. The sensor tip is coated with polyurethane, and the biocompatibility of the tip is investigated by tissue staining. A fully integrated wearable glucose monitoring system is developed with a wireless connection with a smartphone. The test results are in agreement with reference methods. So, we believe the sensor is promising for the development of a continuous glucose monitoring system and diabetes management.     

微波萃取–高效液相色谱荧光检测法测定食品包装用纸中11种荧光增白剂

采用微波萃取高效液相色谱荧光检测法测定食品包装用纸中11种荧光增白剂含量.将样品剪成约0.5 cm×0.5 cm的碎片,用体积分数为40％的乙腈水溶液(含体积分数为0.6％的三乙胺),于80℃微波萃取15 min,用高效液相色谱仪进行定性定量分析.采用Kromasil 100–5型C18柱(250 mm×4.6 mm,5μm)作为分析柱,荧光激发波长为362 nm,发射波长为410 nm,11种荧光增白剂可以较好的分离.11种荧光增白剂质量浓度线性范围为2～150μg/L,相关系数均不小于0.9996,方法检出限为0.1～0.2 mg/kg,定量限为0.3～0.6 mg/kg.样品加标平均回收率为86.0％～108.4％,相对标准偏差为0.4％～4.9％(n=6).该方法前处理简便,检测高效,灵敏度高.     

Application of the Redox-Transmetalation Procedure to Access Divalent Lanthanide and Alkaline-Earth NHC Complexes**

Divalent lanthanide and alkaline-earth complexes supported by N-heterocyclic carbene (NHC) ligands have been accessed by redox-transmetalation between air-stable NHC-AgI complexes and the corresponding metals. By using the small ligand 1,3-dimethylimidazol-2-ylidene (IMe), two series of isostructural complexes were obtained: the tetra-NHC complexes [LnI₂(IMe)₄] (Ln=Eu and Sm) and the bis-NHC complexes [MI₂(IMe)₂(THF)₂] (M=Yb, Ca and Sr). In the former, distortions in the NHC coordination were found to originate from intermolecular repulsions in the solid state. Application of the redox-transmetalation strategy with the bulkier 1,3-dimesitylimidazol-2-ylidene (IMes) ligand yielded [SrI₂(IMes)(THF)₃], while using a similar procedure with Ca metal led to [CaI₂(THF)₄] and uncoordinated IMes. DFT calculations were performed to rationalise the selective formation of the bis-NHC adduct in [SrI₂(IMe)₂(THF)₂] and the tetra-NHC adduct in [SmI₂(IMe)₄]. Since the results in the gas phase point towards preferential formation of the tetra-NHC complexes for both metal centres, the differences between both arrangements are a result of solid-state effects such as slightly different packing forces.     

Pyrolysis and combustion model of oil sands from non-isothermal thermogravimetric analysis data

Thermogravimetric (TG) data of oil sand obtained at Engineering Research Center of Oil Shale Comprehensive Utilization were studied to evaluate the kinetic parameters for Indonesian oil sand samples. Experiments were carried out at heating rates of 5, 15, and 25 °C min^?1 in nitrogen, 10, 20, and 50 °C min^?1 in oxygen atmosphere, respectively. The extent of char combustion was found out by relating TG data for pyrolysis and combustion with the ultimate analysis. Due to distinct behavior of oil shale during pyrolysis, TG curves were divided into three separate events: moisture release, devolatilization, and evolution of fixed carbon/char, where for each event, kinetic parameters, based on Arrhenius theory, were calculated. Coats–Redfern method, Flynn–Wall–Ozawa method, and distributed activation energy model method have been used to determine the activation energies of degradation. The methods are compared with regard to their characteristics and the ease of interpretation of the thermal kinetics. Activation energies of the samples were determined by three different methods and the results are discussed.     

Single‐crystalline gold microplates grown on substrates by solution‐phase synthesis

Chemically synthesized single‐crystalline gold microplates have been attracting increasing interest because of their potential as high‐quality gold films for nanotechnology. We present the growth of tens of nanometers thick and tens of micrometers large single‐crystalline gold plates directly on solid substrates by solution‐phase synthesis. Compared to microplates deposited on substrates from dispersion phase, substrate‐grown plates exhibit significantly higher quality by avoiding severe small‐particle contamination and aggregation. Substrate‐grown gold plates also open new perspectives to study the growth mechanism via step‐growth and observation cycles of a large number of individual plates. Growth models are proposed to interpret the evolution of thickness, area and shape of the plates. It is found that the plate surface remains smooth after regrowth, implying the applicability of regrowth for producing giant plates as well as unique single‐crystalline nano‐structures.     

磷脂膜的相行为对氧化石墨烯与磷脂膜相互作用的影响

通过使用不同相变温度的磷脂分子并调节二者的比例构筑了不同相态的磷脂膜, 并利用表面增强红外光谱和激光共聚焦显微镜研究了磷脂膜的相行为对氧化石墨烯和磷脂膜相互作用的影响. 结果表明, 氧化石墨烯对磷脂膜中磷脂分子的抽提作用具有显著的相态选择性, 其选择性地抽提流动相的磷脂分子; 氧化石墨烯对流动相磷脂的抽提作用受到膜中凝胶相磷脂存在比例的影响, 只有在流动相磷脂分子占磷脂膜中磷脂分子的绝大部分时才能够发生抽提作用, 且只有流动相的磷脂分子被抽提.     

液相色谱-质谱联用法测定血液中全氟化合物

研究了快速溶剂萃取-液相色谱/质谱联用技术测定血液中PFAAs的方法。血液样品经过冷冻干燥,利用加速溶剂萃取的方法,最后使用液相色谱-质谱仪分析检测PFAAs成分。方法的回收率为74.6%~128.8%,检出限为1.10~25.1 ng/L。通过对珠江三角洲地区人群血液样本的分析,发现∑9PFAAs的浓度为26.8~557 ng/g,平均值为176±90.1 ng/g。血液中PFAAs的主要成分以PFHxA和PFOS为主,分别占血液中PFAAs浓度的20.97%和66.98%。人群血液中最常见和浓度最高的PFAAs是PFOS,而PFOA浓度相对较低。