Active Double-Layered Films Enriched with AgNPs in Great Water Dock Root and Pu-Erh Extracts

A novel, eco-friendly, and biocompatible method was applied to form silver nanoparticles (AgNPs) in great water dock (Lapathi radix) (KB) and pu-erh (Camellia sinensis) (PE) extracts. The surface plasma resonance peak of green synthesized AgNPs at 451.8 nm for AgNPs+KB and 440.8 nm for AgNPs+PE was observed via spectral analysis of UV absorbance. In this study, double-layered biopolymer films (FUR/CHIT+HGEL) with AgNPs incorporated in KB solution (AgNPs+KB) and AgNPs in PE solution (AgNPs+PE), were successfully prepared using the casting method. The SEM, XRD, zeta potential and size analyses confirmed the presence of AgNP in the films. The addition of AgNPs in plant extracts improved antimicrobial and antioxidant activity and thermal stability, whereas WVTR experienced a decrease. The nanocomposite films’ orange-brown colour may aid in the protection of food products against UV rays. The composite films demonstrated antibacterial activity against food-borne pathogens and may offer potential in food packaging applications.

Surface discharge during electrical explosion of conductors in strong magnetic fields

In experiments on the electrical explosion of conductors in rapidly growing mega-Gaussian magnetic fields, it was found that at the initial stage of the explosion, “hot spots” up to 500 pieces/mm2 were recorded on the surface. At a later stage, a plasma layer was formed on the surface of the conductor, in which filaments, that is, current channels, were formed. In this work, on the basis of the ecton theory, a model of the development of a surface discharge is constructed. The model makes it possible to estimate, firstly, the magnitude of the current flowing through the surface plasma, and secondly, the thickness of the plasma layer.

Investigation of the near-surface matter density radial distribution in the skin explosion of cylindrical conductors

Investigations of the near-surface plasma formation process during skin explosion of cylindrical duralumin and copper conductors in rapidly increasing magnetic fields with their induction up to 500 T were carried out. The formation of plasma on the conductor surface was recorded by its glow in the visible range using a four-frame optical camera with an exposure time of each frame of 3 ns. The internal structure of the surface plasma, the assessment of the density of matter in it and its radial distribution were investigated using radiography pictures obtained by X-ray transmission with hv > 0.8 keV, which is formed at the “hot point” of the X-pinch. The dependences of the load substance density on its radius were determined and constructed from the obtained X-ray diffraction patterns at different points in time from the beginning of the current. So at 216 ns at a radius of 1.8 mm of a duralumin conductor with an initial radius of 1.485 mm, the density of the substance is estimated to be 0.0068 g/cm3.

Plasma-Driven Photocatalysis Based on Gold Nanoporous Arrays

Various effects caused by surface plasmons including enhanced electromagnetic field, local heating, and excited electrons/holes can not only redistribute the electromagnetic field in the time domain and space but also redistribute the excited carriers and drive chemical reactions. In this study, firstly, an Au nanoporous array photocatalyst with the arrayed gauge was prepared by means of the anodic alumina template. Then, the formation of 4,4′-dimercaptoazobenzene (DMAB) by the surface plasmon-driven photocatalysis under 633 nm laser irradiation was investigated by means of Raman spectroscopy using aminothiophenol (PATP) as a probe molecule on gold nananoporous arrays. In addition, sodium borohydride was introduced in situ to realize the reverse photocatalytic reaction driven by the surface plasma. With the help of FDTD software, the plasma distribution characteristics on the surface of Au nanoporous arrays were simulated and analyzed. Through this practical method, it is expected to draw specific graphics, letters, and Chinese characters on the micro/nano scale, and realize the functions of graphics drawing, information encryption, reading, and erasing on the micro/nano scale.

Enhancement of Planar Orientation of Reactive Mesogen Molecules for Optical Retarder Film by Anisotropic Surface Plasma Treatment

We proposed a method for enhancing the planar orientation of reactive mesogen (RM) molecules by means of anisotropic plasma treatment. Anisotropic surface plasma, of which energy density is dependent on the azimuthal angle, was generated by column-shaped ceramic electrodes. The anisotropic plasma was discharged on the surface of a polyvinyl alcohol (PVA) alignment layer before the rubbing process began. The contact angle of the surface was increased from 12° to 83° after plasma treatment, indicating a hydrophobic property of the surface. From the atomic force microscopy (AFM) measurement, it was found that the grain size of the PVA layer was reduced and that the grooved patterns were formed provided that the plasma direction was parallel to the rubbing direction of the surface. Consequently, the planar orientation was enhanced, and the in-plane retardation of the photo-polymerized RM films increased when the parallel plasma was treated on the surface.