Facile synthesis of a triptycene-based porous organic polymer with a high efficiency and recyclable adsorption for organic dyes

Water contamination resulting from organic dyes has had severe detrimental effects on human health and environmental tolerance. To address this issue, a delicate strategy for taking host–guest function in porous organic polymers via a facile Friedel–Crafts reaction of triptycene and post-modification was achieved. By means of this route, a sulfonic acid functionalized triptycene-based porous organic polymer (TPOP–SO₃H) with a hierarchical structure and a desirable Brunauer–Emmett–Teller value of 1002 m²/g was synthesized this study. The TPOP–SO₃H material demonstrated a maximum adsorption capacity for methylene blue of 97.1 mg/g. Remarkably, an absorption efficiency of more than 90% of TPOP–SO₃H was observed even after five cycles. Therefore, such a hierarchical porous organic polymer can be highly recommended as one type of promising material for the treatment of organic dye-polluted wastewater. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47987.     

Micro‐morphological,environmental and phytochemical investigation of herbal medicines by using LM and SEM: A quality control tool

The use of quality control tool for authentication of Jadwar (Delphinium denudatum Wall. ex Hook.f. & Thomson), a folk herbal drug used for the treatment of different ailments, was studied. People face problems of adulteration for this drug at global, regional, national and local levels. Two different plant species are commercially marketed in the Indo‐Pak Subcontinent under the same trade name of Jadwar. One is D. denudatum Wall. ex Hook.f. & Thomson and the other is Aconitum heterophyllum Wall. ex Royle. To focus on this problem, a marketable available drug sample of Jadwar was authenticated by using basic microscopy tools (LM) and advanced chemo‐taxonomic markers. Authentication, quality and standardization of this drug was achieved using morphology, organoleptography, UV and IR analyses, scanning electron microscopy of pollen and anatomical investigations. The techniques used for authentication marked the clear difference between the studied plants. Microscopic studies, chemotaxonomic investigation and other techniques used in this project provided the basis for the authentication of this species.     

Soluble network polymers based on trifluoropropyl-substituted open-cage silsesquioxane: Synthesis,properties, and application for surface modifiers

Fluorinated completely condensed polyhedral oligomeric silsesquioxanes (F-CC-POSSs) are widely utilized as surface modifiers for polymeric materials because of their polyhedral and fluorine-rich structures, which generate polymers with lower surface energies under molecular-level control. In contrast, their derivatives, fluorinated incompletely condensed or open-cage POSSs (F-IC-POSSs), have similarly intriguing structures, but their utilization for polymer synthesis remains undeveloped. Herein, fluorinated network polymers were prepared based on a 3,3,3-trifluoropropyl-substituted IC-POSSs via hydrosilylation polymerization with isobutyl- and phenyl-substituted IC-POSS under optimized conditions. In addition to their good thermal stability and tunable refractive indices, these polymers exhibited solution processability and their casting films showed excellent optical transparency, indicating their potential for constructing fluorinated polymers. Their utilization as surface modifiers was examined by addition to poly(methylmethacrylate) (PMMA) films. Intriguingly, modified PMMA films with 2.0 and 0.5 wt% addition showed similar hydrophobicity and surface energies to the films prepared with only fluorinated network polymers.     

Kinetics of the cyclization and isomerization reactions in polyacrylonitrile based carbon fiber precursors during thermal-oxidative stabilization

The kinetics of reactions in polyacrylonitrile (PAN) based carbon fiber (CF) production should be of significance to the guidance of process control, fiber structure formation. PAN precursor fibers were isothermally stabilized at 210, 225, 240, 255, and 270 °C, respectively, for 10 to 100 min in an air oven to study the kinetics of the cyclization and isomerization reactions. The structural evolution of PAN precursor fibers during thermal-oxidative stabilization was characterized by Fourier transform infrared (FTIR) spectroscopy and solid state ¹³C nuclear magnetic resonance (¹³C NMR). The results indicate that the FTIR absorbance of  CN (the resultant of the cyclization) in PAN shows a trend of first increasing and then decreasing. And then the NMR peak assigned to the carbon atoms linking imino groups ( NH ) proves the isomerization of  CN into  NH in pyridone structure. Based upon the FTIR absorbance method, the entire process of the cyclization and isomerization reactions is considered as a consecutive first-order reaction. A kinetic model for the consecutive reaction has been established via the evaluation of the reaction rate constants of two single reactions. According to the model, the simulated kinetic curves of the characteristic groups ( CN,  CN , and  NH ) conform to the FTIR absorbance trends of these groups based on experimental data. This study is expected to furnish in-depth information on the crucial reaction kinetics during stabilization of PAN precursors, which is of advantage to the process optimization of the CF production. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48819.     

Extraction of Distinguished Hyperbolic Trajectories for 2D Time-Dependent Vector Field Topology

This paper does two main contributions to 2D time-dependent vector field topology. First, we present a technique for robust, accurate, and efficient extraction of distinguished hyperbolic trajectories (DHT), the generative structures of 2D time-dependent vector field topology. It is based on refinement of initial candidate curves. In contrast to previous approaches, it is robust because the refinement converges for reasonably close initial candidates, it is accurate due to its adaptive scheme, and it is efficient due to its high convergence speed. Second, we provide a detailed evaluation and discussion of previous approaches for the extraction of DHTs and time-dependent vector field topology in general. We demonstrate the utility of our approach using analytical flows, as well as data from computational fluid dynamics.     

A new particle swarm optimization algorithm with adaptive inertia weight based on Bayesian techniques

Particle swarm optimization is a stochastic population-based algorithm based on social interaction of bird flocking or fish schooling. In this paper, a new adaptive inertia weight adjusting approach is proposed based on Bayesian techniques in PSO, which is used to set up a sound tradeoff between the exploration and exploitation characteristics. It applies the Bayesian techniques to enhance the PSO's searching ability in the exploitation of past particle positions and uses the cauchy mutation for exploring the better solution. A suite of benchmark functions are employed to test the performance of the proposed method. The results demonstrate that the new method exhibits higher accuracy and faster convergence rate than other inertia weight adjusting methods in multimodal and unimodal functions. Furthermore, to show the generalization ability of BPSO method, it is compared with other types of improved PSO algorithms, which also performs well.     

State-of-the-art of non-destructive measurement of sub-surface material properties and damages

The possibilities of common non-destructive measuring techniques are reviewed in this paper for their applications in precision engineering. The grazing X-ray technique is believed to be a powerful improvement of the conventional X-ray techniques under both the diffraction mode and the fluorescent mode. Information of the crystallographic structure and chemical composition can be obtained to a nanometre resolution. Ultrasound can be used in scanning acoustic microscopy to give information on the physical or even chemical nature of superficial layers. Raman spectroscopy has now become an important tool for studying superficial structures, chemical composition and stresses in cyrstalline and amorphous materials: it is recommended to use this method especially for the investigation of monocrystalline silicon and germanium. The instrumented microindentation technique is a quasi- non-destructive technique for evaluating mechanical material properties like hardness and Young's modulus in a nanometre range. It can be used on any material that does not require special surroundings like a vacuum. Photothermal microscopy has been developed recently for the non-destructive testing of the local thermal properties of materials. By using the Mirage effect and its local measurement above the surface, a non-destructive depth profiling of surface damages can be obtained.