A cost-effective and practical polybenzanthrone-based fluorescent sensor for efficient determination of palladium (II) ion and its application in agricultural crops and environment

A highly selective and sensitive fluorescent chemosensor suitable for practical measurement of palladium ion (Pd²⁺) in agricultural crops and environment samples has been successfully fabricated using polybenzanthrone (PBA). PBA was facilely electrosynthesized in the mixed electrolyte of acetonitrile and boron trifluoride diethyl etherate. The fluorescence intensity of PBA showed a linear response to Pd²⁺ in the concentration range of 5 nM–0.12 mM with a detection limit of 0.277 nM and quantification limit of 0.925 nM. Different compounds existing in agricultural crops and environment such as common metal ions, anions, natural amino acids, carbohydrates, and organic acids were used to examine the selectivity of the as-fabricated sensor, and no obvious fluorescence change could be observed in these interferents and their mixtures. A possible mechanism was proposed that the coordination of PBA and Pd²⁺ enhance the aggregation of polymer chains, which led to a significant quenching of PBA emission, and this was further confirmed by absorption spectra monitoring and transmission electron microscopy. The excellent performance of the proposed sensor and satisfactory results of the Pd²⁺ determination in practical samples suggested that the PBA-based fluorescent sensor for the determination of Pd²⁺ will be a good candidate for application in agriculture and environment.     

Study of the solubility of CO2, H2S and their mixture in the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate: Experimental and modelling

New experimental results are presented for the solubility of carbon dioxide, hydrogen sulfide in the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate ([C₈mim][PF₆]) at temperatures range from (303.15 to 353.15) K and pressures up to about 2 MPa. The solubility of the mixture of CO₂/H₂S in [C₈mim][PF₆] under various feed compositions were also measured at temperatures of (303.15, 323.15 and 343.15) K and the pressure up to 1 MPa. The solubility of carbon dioxide and hydrogen sulfide increased with increasing pressure and decreased with increasing temperature and the solubility of H₂S is about three times that of CO₂ in the particular ionic liquid studied. The measured data were correlated using extended Henry’s law included Pitzer’s virial expansion for the excess Gibbs energy, and the generic Redlich–Kwong cubic equation of state proposed for gas/ionic liquid systems. The correlations from the two models show quite good consistency with the experimental data for CO₂/IL and H₂S/IL binary mixtures within experimental uncertainties. For CO₂/H₂S/IL ternary mixtures, the RK model shows better correlation with the experimental values. We also studied the effect of cation alkyl chain length on the CO₂ and H₂S solubility by comparison of the experimental data of this study with those of previous reports. As the cation alkyl chain length became longer, the solubility of CO₂ and H₂S increased in the ionic liquid. Additionally, the influence of the anion on the solubility is studied by comparing the solubility of CO₂ and H₂S in [C₈mim][PF₆] with those in [C₈mim][Tf₂N]. As a result, CO₂ and H₂S have higher solubility in the IL with [Tf₂N]⁻ as the anion.     

Structural Design and Applications of Stereoregular Fused Thiophenes and Their Oligomers and Polymers

Abstract

Stereoregular fused thiophenes (SFTs: especially thieno[3,2-b]thiophene (TT) and dithieo[3,2-b:2′,3′-d]thiophene (DTT)), as stable conjugated structures deriving from thiophene ring enlargement, possess outstanding properties and special configuration, such as the superior carrier transfer efficiency and a high degree backbone of planarity. In comparison to stand-alone SFTs structures, oligomers and polymers containing different heteroaromatic units have been much widely researched and used in many fields. In decade, several important reviews have summarized the broad field of fused thiophenes including SFTs, and their synthesis and optoelectronic applications. Here, we critically present the structure–performance relationships and application of oligomers and polymers containing SFTs (exhibiting thiophene ring number from 2 to 7) units. First, the basic structures and properties of SFTs are briefly stated. Then, oligomers classified by extra conjugated heterocyclic attachments are carefully discussed, focusing on the structure–performance relationships for their optoelectronic applications including organic photovoltaic cells and organic field-effect transistors. Moreover, such relationships in polymers have been applied in much wider fields such as organic light-emitting diodes, electrochromic devices, thermoelectric devices, and supercapacitors are discussed. Finally, a summary and prospect are given. Through this review, instruction for molecular design and novel ideas for the future development of SFTs-contained are provided.     

Huperzine A: A Mini-Review of Biological Characteristics,Natural Sources,Synthetic Origins,and Future Prospects

Russian Journal of Organic Chemistry - Huperzia serrate is a known medicinal plant that produces the Lycopodium alkaloid Huperzine A (HupA). It has been used to treat such diseases as contusions,...     

Cellulose nanocrystals as biobased nucleation agents in poly-l-lactide scaffold: Crystallization behavior and mechanical properties

The mechanical strength of polymer scaffold is closely related to its crystallinity. In this work, cellulose nanocrystals (CNC) were incorporated into poly-l-lactide (PLLA) scaffold which was fabricated by selective laser sintering, aiming to improve the mechanical properties. CNC possesses numerous hydroxyl groups which might form hydrogen bond with PLLA molecular chains. The hydrogen bond induces the ordered arrangement of PLLA chain by using CNC as heterogeneous nucleating agent, thereby increasing crystallization rate and crystallinity. Results showed that PLLA scaffolds with 3 wt% CNC resulted in 191%, 351%, 34%, 83.5%, 56% increase in compressive strength, compressive modulus, tensile strength, tensile modulus and Vickers hardness, respectively. Encouragingly, with the incorporation of hydrophilic CNC, the PLLA/CNC scaffolds showed not only better hydrophilicity, but also faster degradation than PLLA. In vitro cell culture studies proved that the PLLA/CNC scaffolds were biocompatible and capable of supporting cell adhesion, proliferation and differentiation. The above results indicated that the PLLA/CNC scaffolds may therefore be a potential replacement in bone repair.     

A Comparison Investigation of Coix Seed Oil Liposomes Prepared by Five Different Methods

The physicochemical properties of coix seed oil (CSO) liposomes prepared by five different methods were evaluated for morphology, encapsulating efficiency, particle size, storage stability, and in vitro release. The different preparation methods resulted in several types of vesicles with different properties. The type of vesicles was closely related to leakage pattern, which affected the storage stability and in vitro release profiles. Ethanol injection method was the best choice for preparing safe and stable liposomes with controlled release. The release mechanisms might account for the diffusion of CSO, and Higuchi was the most suitable model for liposomes stored at high temperature or released in simulated intestinal fluid (SIF).     

基于偏最小二乘与广义回归神经网络的近红外光谱测定土豆中3种营养成分的研究

偏最小二乘(partial least squares,PLS)与广义回归神经网络(generalized regression neural networks,GRNN)联用对土豆样品建立起粗纤维、淀粉、蛋白质含量的预测校正模型,用PLS法将原始数据压缩为主成份,取前3个主成份的12个特征吸收峰输入GRNN网络,网络光滑因子σi为0.1.PLS-GRNN模型对样品3个组分含量的预测决定系数(R2)分别为: 0.945、 0.992、 0.938.结果表明,近红外光谱技术可以快速、准确地同时测定土豆中的粗纤维、淀粉、蛋白质,该方法可应用于果蔬产业的品质管理与控制.     

Solution properties of poly(amic acid)–NMP containing LiCl and their effects on membrane morphologies

Physical properties of poly(amic acid) (PAA) casting solutions in N-methyl-2-pyrrolidone (NMP) containing lithium chloride (LiCl) were characterized by viscometry and dynamic light scattering (DLS) and were related to the morphological properties of asymmetric membranes prepared from these solutions. At a fixed polymer concentration, the increase in viscosity of the PAA solutions with increasing LiCl content is mainly determined by the viscosity of the salt–solvent medium, implying that the LiCl–NMP interactions are stronger than those between LiCl and PAA. Because of the strong salt–solvent interactions, complexes between LiCl and NMP are formed. The complexes reduce the solvent power of NMP for PAA inducing polymer aggregation (clustering) and/or transient cross-links in the solutions. Dynamic light scattering results for salt-containing solutions at low PAA concentrations support the existence of these aggregations. Solutions without salt showed a single relaxation, but solutions with LiCl exhibit multiple relaxation modes; two diffusional modes of cooperative and aggregates, and one angle independent transient network mode. The polymer aggregates and transient cross-links form a gel-like structure in the casting solution film and hinder macrovoid formation during phase inversion, resulting in asymmetric membranes with a primarily sponge-like structure.     

Electrochemical studies on Nafion membrane

Electrochemical characterization of Nafion membrane on the basis of membrane potential and membrane conductance measurements has been carried out to investigate variation in its permselectivity with composition of the electrolyte solutions. Possibility of prevention of reduction in the ion selective character of the membrane with increase in concentration upon immobilization of sodium dodecyl sulphate and dodecyl alcohol has been explored. Correlation between the extent of immobilized surfactants and improvement in ion selectivity of the membrane has also been attempted.