Peptide‐functionalized reduced graphene oxide as a bioactive mechanically robust tissue regeneration scaffold

Bioactive, synthetic materials represent next‐generation composites for tissue regeneration. Design of contemporary materials attempts to recapitulate the complexities of native tissue; however, few successfully mimic the order in nature. Recently, graphene oxide (GO ) has emerged as a scaffold due to its potential for bioactive functionalization and long‐range order instilled by the self‐assembly of graphene sheets. Chemical reduction of GO results in a more compatible material with enhanced properties but compromises the ability to functionalize the graphenic backbone. However, using Johnson–Claisen rearrangement chemistry, functionalization is achieved that is not liable to reduction. From reduced Claisen graphene, we polymerized short homopeptides from α ‐amino acid N ‐carboxyanhydride monomers of glutamate and lysine to result in functionalized graphenes (pGlu‐rCG and pLys‐rCG ) that are cytocompatible, degradable, and bioactive. Exposure to NIH‐3T3 fibroblasts and RAW 264.7 macrophages revealed that the materials are cytocompatible and do not alter important sub‐cellular compartments. Powders were hot pressed to form mechanically stiff (E ′: 41 and 49 MPa ), strong (UCS : 480 and 140 MPa ), and tough (U _T: 2898 and 584 J m^?3 × 10⁴) three‐dimensional constructs (pGlu‐rCG and pLys‐rCG, respectively). Overall, we report a robust chemistry and processing strategy for facile bioactive functionalization of compatible, reduced Claisen graphene for three‐dimensional biomedical applications. © 2017 Society of Chemical Industry     

ATR-FTIR结合判别分析法快速鉴别天然柠檬风味精油种类

以5种山苍子精油、2种柠檬草精油为研究对象,采用ATR-FTIR结合判别分析法建立了几类天然柠檬风味精油的识别模型。模型清晰地将样品分成了3大类:低浓度柠檬醛精油、高浓度柠檬醛精油、烯烃类(柠檬烯及长叶烯)精油。利用模型可以简便、快速地鉴别不同类型的天然柠檬风味精油,为天然柠檬风味精油的快速鉴别提供了一种新的方法。     

DMAB显现纸张表面潜在手印应用研究

纸张类客体是案件现场中常见的一类检材,其表面潜在手印的显现在物证检验鉴定过程中具有重要的意义。利用氨基酸敏感试剂N,N-二甲基-4-氨基苯甲醛(DMAB)对纸张表面潜在手印进行显现研究,结果表明,当浓度为0.4%时,DMAB对纸张表面潜在手印有很好的显现效果,显现手印在490 nm光源照射时,橙色护目镜下可观察到黄色荧光。该方法显现灵敏度高、显出手印纹线清晰、与背景反差较大,对于遗留30 d的陈旧性手印仍具有良好的显现效果。     

微丝菌培养分离、特性标记及调控研究进展

污泥膨胀一直是困扰污水处理厂正常运行的一个世界性难题,而微丝菌是污泥丝状膨胀中的主要丝状菌,因此对微丝菌本质规律的研究不仅有利于认识微丝菌,也可提供诸多控制污泥丝状膨胀的方法。综述了微丝菌在培养分离、生理特性和影像识别以及调控等方面的研究进展,并对微丝菌的后续研究提出了建议和展望。     

Improved protein resistance of silicone hydrogels by grafting short peptides for ophthalmological application

A simple and facile approach to impart the antifouling properties of silicone hydrogels was developed in this report. Short peptides were first tethered to silicone hydrogels through terminal amino group-induced epoxy ring-opening click reaction. The modified silicone hydrogels have improved hydrophilicity and protein adsorption resistance because of the formation of zwitterionic structure of the grafted peptides. Furthermore, glycylglycine and diglycyl glycine-modified silicone hydrogel contact lenses were fabricated. They exhibited favorable antifouling property and no damage to rabbits’ eyes after continuous wearing. The short peptide modified silicone hydrogel contact lenses have potential application in ophthalmology.     

Laser-Based Measurement of Gas–Liquid Two-Phase Flows in Micro and Mini Channels using Multiple Photodiode Arrangement

Two-phase flow measurement is important in process and chemical industries. In the present work, a measurement technique for the characterization of two-phase flows using a laser and an arrangement of the photodiodes is proposed and tested. Two-phase flow experiments were carried out in 1.80, 3.14, and 4.68-mm-diameter glass tubes. A high-speed camera was used to analyze the various optical patterns formed by a stationary laser beam on a screen during bubbly, slug, and stratified flows, which have been discussed in detail in Navisa et al. (2015 Navisa, J., Balachandar, C., Arunkumar, S., and Venkatesan, M. (2015). Characterisation of gas-liquid two-phase flows using LASER patterns, Can. J. Chem. Eng., 93(9), 1678–1685.[Crossref], [Web of Science ®] , [Google Scholar]). Photodiodes are arranged on the screen based on high-speed camera recordings. A procedure is demonstrated to calculate the flow regime velocity and length based on the photodiode outputs. The designed nonintrusive instrumentation determines the two-phase flow parameters in real time for flow in optically transparent mini channels. The accuracy of the measurement technique and the limitations are also discussed.     

洱海流域北部入湖河流污染特征分析

罗时江在洱海北部三条重要入湖河流中受污染程度最高,是北部入湖河流控制与治理的重点。该文采用综合水质标识指数评价法来研究罗时江流域内不同时期的污染特征变化。结果表明全年罗时江水体中总氮和总磷的标识指数都维持在较高水平,整个流域受来自农业面源的营养盐污染严重。在不同季节,罗时江受各项污染指标的污染程度是不同的。夏季罗时江水体中有机污染水平最高,综合评定罗时江重点的污染时段为春季和夏季。     

PARAMETER ESTIMATION OF FICK'S LAW DRYING EQUATION

ABSTRACT

Distributed parameter drying models such as the Fick's law diffusion model, unlike the lumped parameter model of van Meel whose parameters can be easily estimated by regression, suffer from the difficulty in estimating the parameters of the models quantitatively with accuracy. In the past they were estimated by visual inspection of the theoretical drying curves which fit the experimental drying curve best In this work, a quantitative parameter estimation technique originally suggested by Chavent, is developed by minimizing the integrated squares of error between theoretical and experimental curves over the drying lime (the criterion) subjected to the constraints that the theoretical curve is governed by the constant diffusivity Fick's taw diffusion equation (the constraint). Although the estimation of Fick's law constant diffusivity can be done by using the analytical solution developed by Crank, the use of the Fick's law model here is simply to demonstrate the utility of the proposed technique which can be used in more complex distributed models. The optimization problem is to solve for the adjoint equation for which the value of the Fick's law diffusivity minimizes the criterion. The Lagrangian derivative is solved by using a discrete derivative of the criterion. The theoretical curves are generated by using simple explicit (FSE) and modified Crank-Nicholson (FCR) algorithms The drying of oil palm kernels are used as a case study. Ii is found that the estimated diffusivities of moisture in oil palm kernels range from 0 5 to 5.0 × 10^-10 m²sol;s which are comparable with published data. It is also found that the estimated diffusivity is dependent on the initial moisture content.     

Macrocyclization of Organo‐Peptide Hybrids through a Dual Bio‐orthogonal Ligation: Insights from Structure–Reactivity Studies

Macrocycles constitute an attractive structural class of molecules for targeting biomolecular interfaces with high affinity and specificity. Here, we report systematic studies aimed at exploring the scope and mechanism of a novel chemo‐biosynthetic strategy for generating macrocyclic organo‐peptide hybrids (MOrPHs) through a dual oxime‐/intein‐mediated ligation reaction between a recombinant precursor protein and bifunctional, oxyamino/1,3‐amino‐thiol compounds. An efficient synthetic route was developed to access structurally different synthetic precursors incorporating a 2‐amino‐ mercaptomethyl‐aryl (AMA) moiety previously found to be important for macrocyclization. With these compounds, the impact of the synthetic precursor scaffold and of designed mutations within the genetically encoded precursor peptide sequence on macrocyclization efficiency was investigated. Importantly, the desired MOrPHs were obtained as the only product from all the different synthetic precursors probed in this study and across peptide sequences comprising four to 15 amino acids. Systematic mutagenesis of the “i?1” site at the junction between the target peptide sequence and the intein moiety revealed that the majority of the 20 amino acids are compatible with MOrPH formation; this enables the identification of the most and the least favorable residues for this critical position. Furthermore, interesting trends with respect to the positional effect of conformationally constrained (Pro) and flexible (Gly) residues on the reactivity of randomized hexamer peptide sequences were observed. Finally, mechanistic investigations enabled the relative contributions of the two distinct pathways (side‐chain→C‐end ligation versus C‐end→side‐chain ligation) to the macrocyclization process to be dissected. Altogether, these studies demonstrate the versatility and robustness of the methodology to enable the synthesis and diversification of a new class of organo‐peptide macrocycles and provide valuable structure–reactivity insights to inform the construction of macrocycle libraries through this chemo‐biosynthetic strategy.