Green Synthesis of Glycopolymers Using an Enzymatic Approach

beta-Glucosidase and horseradish peroxidase (HRP) are used as biocatalysts in aqueous solution for the enzymatic synthesis of glycomonomers and the respective enzymatic polymerization toward glycopolymers. The biocatalytically synthesized monomers contain (meth)acrylate functionalities that are able to be polymerized by an enzyme-initiated polymerization using an HRP/hydrogen peroxide/acetylacetone ternary system. The structure of the glycomonomers and the respective glycopolymers as well as the monomer conversion after the reaction are determined by H-1 NMR spectroscopy. The synthesized glycopolymers have a dispersity and a number-average molecular weight up to 5.8 and 297 kg mol(-1), respectively. Thermal and degradation properties of the glycopolymers are studied by differential scanning calorimetry and thermogravimetric analysis. In addition, preparation of glycopolymers via conventional free radical polymerization is performed and the properties of the obtained polymers are compared with the enzymatically synthesized glycopolymers

Surface waves in a magnetized ferrite slab filled with a wire medium

Novel metamaterial, based on wire medium embedded into magnetized ferrite, is studied. Waves in unbounded ferrites filled with wire media, surface wave at the interface of this metamaterial and the air as well as waves in a ferrite slab adjacent to a wire medium are considered. Different geometries of wires arrangement and different magnetization directions are discussed. Effective permeability was introduced for the case where both plasma and magnetic properties take place. Dispersion diagrams and applicability of the Drude model for the description of the wire medium in a host matrix, possessing high permittivity and permeability, are discussed

Q-factor investigation of antennas over metamaterials substrates

International audienceIn this article, antennas over metamaterials substrates are investigated with the radiating Q factor determined by using a time‐domain method.The main objective is to illustrate the electromagnetic behavior of this kind of complex structure by calculating its energy budget (stored and radiated energies). An example of a patch antenna using such materials is analyzed and experimental results are presented

1D squeeze flow analysis of chopped long fibre thermoplastic composite

Long fibre thermoplastic (LFTs) in the form of chopped tapes are well known as they combine relatively high mechanical performance and good formability compared to respectively short and continuous fibre reinforced composites. Complex shapes can be manufactured with high fibre content with compression moulding [1], which makes these thermoplastic composite chopped tapes a good candidate for industrial applications. During moulding, the flow of fibre reinforced polymer leads to an altered fibre orientation distribution which affects the final mechanical properties of the part [1-4]. In order to predict the mechanical performance, it is therefore important to understand the mould filling behaviour of the LFTs. In spite of being used in the industry for quite a long time, the complex flow behaviour of LFTs in processes like compression moulding is still a challenge to predict. Although the flow in the compression moulding process is usually limited, it is critical for the final part quality. In flat geometries, it is not known whether flow during mould filling is affine/single-phase where polymer and fibres move together or dual-phase where they move separately, which can result in fibre-matrix separation. In order to model the compression moulding process, one needs to know either single- or dual-phase flow is applicable. The objective of this work is to investigate the separation of the resin from fibres and to realize this objective, 1D squeeze flow experiments are performed in a flat geometry. Chopped unidirectional tapes of carbon/polyethersulfone were used for the experiments. Different processing conditions were used in experiments with a mould which was filled only partially. A burn-off method was used to analyze the fibre mass fraction. The samples for the burn-off test were taken along the flow direction. Results of polymer burn-off did not show significant changes in the fibre mass fraction along the flow direction and therefore the flow can be assumed to behave as a single-phase flow

Picture-perfect Streaming over the Internet: Is There Hope?

Quality of service (QoS) in streaming of continuous media (CM) over the Internet is poor, which is partly due to variations in delays, bandwidth limitations, and packet losses. Although CM applications can tolerate some missing data, non-recoverable information loss degrades these applications' QoS. Consequently, a number of application areas (e.g., those related to the entertainment industry) have backed away from streaming of their content over the Internet

A combined computational and experimental approach reveals the structure of a C/EBP–Spi1 interaction required for IL1B gene transcription

We previously reported that transcription of the human IL1B gene, encoding the proinflammatory cytokine interleukin 1, depends on long-distance chromatin looping that is stabilized by a mutual interaction between the DNA-binding domains (DBDs) of two transcription factors: Spi1 proto-oncogene at the promoter and CCAAT enhancer– binding protein (C/EBP) at a far-upstream enhancer. We have also reported that the C-terminal tail sequence beyond the C/EBP leucine zipper is critical for its association with Spi1 via an exposed residue (Arg-232) located within a pocket at one end of the Spi1 DNA-recognition helix. Here, combining in vitro interaction studies with computational docking and molecular dynamics of existing X-ray structures for the Spi1 and C/EBP DBDs, along with the C/EBP C-terminal tail sequence, we found that the tail sequence is intimately associated with Arg-232 of Spi1. The Arg-232 pocket was computationally screened for small-molecule binding aimed at IL1B transcription inhibition, yielding L-arginine, a known anti-inflammatory amino acid, revealing a potential for disrupting the C/EBP–Spi1 interaction. As evaluated by ChIP, cultured lipopolysaccharide (LPS)-activated THP-1 cells incubated with L-arginine had significantly decreased IL1B transcription and reduced C/EBP’s association with Spi1 on the IL1B promoter. No significant change was observed in direct binding of either Spi1 or C/EBP to cognate DNA and in transcription of the C/EBP-dependent IL6 gene in the same cells. These results support the notion that disordered sequences extending from a leucine zipper can mediate protein–protein interactions and can serve as drug-gable targets for regulating gene promoter activity