Abstract
Magnetron discharge plasma was applied for the synthesis of CN
x
thin layers using methane and nitrogen gas precursors. The incorporation of nitrogen in the carbon network resulted in the ...dramatic evolution of growth morphology: from a ‘buried’ porous layer observed at low nitrogen incorporation to aligned bundles of nanorods grown perpendicular to the substrate surface at maximum discharge power and nitrogen flow. The films deposited at the low discharge power and high nitrogen incorporation exhibited a mesoporous sponge-like morphology after vacuum annealing. Relevant physical mechanisms responsible for the formation of nano- and mesoshaped morphology are discussed in terms of the effects of internal mechanical stresses and plasma etching. In addition, the sensing properties of the sponge-like layer were preliminarily examined in water vapor and ammonia ambients. The CN
x
films showed enhanced sensitivity to ammonia and reverse electrical response to moisture in comparison with a nitrogen-free nanoporous carbon film, which were assigned to modification of the electronic properties of the nitridated surface.
Abstract We have experimentally studied the relationship in between non-collinear magnetization states in ferromagnetic (FM) multilayers and their resulting magneto-optical (MO) properties. Hereby, ...we observe that the phase of the complex-valued MO parameters are especially sensitive towards non-collinear magnetization states and enable their unambiguous detection. For the purpose of our experimental study, we designed, fabricated and characterized a set of epitaxial FM/NM/FM multilayers with in-plane uniaxial anisotropy, in which the non-magnetic (NM) interlayer thickness t was varied, so that tunable FM interlayer exchange coupling strength in between the two FM layers could be achieved. Furthermore, the two FM layers were made from different alloys, so that they exhibit different levels of magnetocrystalline anisotropy, which enables a collinear to non-collinear magnetization state transition upon applying a magnetic field H away from the in-plane easy axis for samples with sufficiently large t . Utilizing generalized MO ellipsometry, we determined the full reflection matrix R as a function of H and we observed that the phases of the complex-valued MO coefficients in R change with H in multilayers that have sufficiently weak interlayer coupling strength, i.e. large t , which can only happen if non-collinear magnetization states of varying non-collinearity occur in those samples. For samples with small t , corresponding to strongly exchange coupled FM layers, this effect is absent, consistent with the existence of collinear magnetization states in those multilayers for all H values.
•Molecularly imprinted polypyrrole (MIP-Ppy) based electrochemical sensor is reported.•SARS-CoV-2-S spike glycoprotein was imprinted within Ppy in order to design MIP-Ppy.•Pulsed amperometric ...detection (PAD) was applied as electroanalytical method.•Complex evaluation of PAD-based electroanalytical signal was performed.•A selectivity of MIP-Ppy-based sensor was determined.
This study describes the application of a polypyrrole-based sensor for the determination of SARS-CoV-2-S spike glycoprotein. The SARS-CoV-2-S spike glycoprotein is a spike protein of the coronavirus SARS-CoV-2 that recently caused the worldwide spread of COVID-19 disease. This study is dedicated to the development of an electrochemical determination method based on the application of molecularly imprinted polymer technology. The electrochemical sensor was designed by molecular imprinting of polypyrrole (Ppy) with SARS-CoV-2-S spike glycoprotein (MIP-Ppy). The electrochemical sensors with MIP-Ppy and with polypyrrole without imprints (NIP-Ppy) layers were electrochemically deposited on a platinum electrode surface by a sequence of potential pulses. The performance of polymer layers was evaluated by pulsed amperometric detection. According to the obtained results, a sensor based on MIP-Ppy is more sensitive to the SARS-CoV-2-S spike glycoprotein than a sensor based on NIP-Ppy. Also, the results demonstrate that the MIP-Ppy layer is more selectively interacting with SARS-CoV-2-S glycoprotein than with bovine serum albumin. This proves that molecularly imprinted MIP-Ppy-based sensors can be applied for the detection of SARS-CoV-2 virus proteins.
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We have synthesized four types of cyclopentadithiophene (CDT)‐based low‐bandgap copolymers, poly{4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta2,1‐b:3,4‐b′dithiophene‐2,6‐diyl}‐alt‐(2,2′‐bithiazole‐5,5′‐diyl) ...(PehCDT‐BT), poly(4,4‐dioctyl‐4H‐cyclopenta2,1‐b:3,4‐b′dithiophene‐2,6‐diyl)‐alt‐(2,2′‐bithiazole‐5,5′‐diyl) (PocCDT‐BT), poly{4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta2,1‐b:3,4‐b′dithiophene‐2,6‐diyl}‐alt‐{2,5‐di(thiophen‐2‐yl)thiazolo5,4‐dthiazole‐5,5′‐diyl} (PehCDT‐TZ), and poly(4,4‐dioctyl‐4H‐cyclopenta2,1‐b:3,4‐b′dithiophene‐2,6‐diyl)‐alt‐{2,5‐di(thiophen‐2‐yl)thiazolo5,4‐dthiazole‐5,5′‐diyl} (PocCDT‐TZ), for use in photovoltaic applications. The intramolecular charge‐transfer interaction between the electron‐sufficient CDT unit and electron‐deficient bithiazole (BT) or thiazolothiazole (TZ) units in the polymeric backbone induced a low bandgap and broad absorption that covered 300 nm to 700–800 nm. The optical bandgap was measured to be around 1.9 eV for PehCDT‐BT and PocCDT‐BT, and around 1.8 eV for PehCDT‐TZ and PocCDT‐TZ. Gel permeation chromatography showed that number‐average molecular weights ranged from 8000 to 14 000 g mol−1. Field‐effect mobility measurements showed hole mobility of 10−6–10−4 cm2 V−1 s−1 for the copolymers. The film morphology of the bulk heterojunction mixtures with 6,6phenyl‐C61‐butyric acid methyl ester (PCBM) was also examined by atomic force microscopy before and after heat treatment. When the polymers were blended with PCBM, PehCDT‐TZ exhibited the best performance with an open circuit voltage of 0.69 V, short‐circuit current of 7.14 mA cm−2, and power conversion efficiency of 2.23 % under air mass (AM) 1.5 global (1.5 G) illumination conditions (100 mW cm−2).
Mind the bandgap: Four types of cyclopentadithiophene (CDT)‐based low‐bandgap copolymers with two thiazole derivatives based on thiazolothiazole (TZ) and bithiazole (BT) structures have been synthesized (see picture for examples). The internal charge‐transfer interaction between the electron‐sufficient CDT unit and electron‐deficient TZ or BT units in the polymeric backbone induces a low bandgap.
Conducting incident waves to transmission and reflection channels via artificial graphene patterns make it possible to realize a wave duplexer. In this way, a multi layers device is introduced and ...simulated. The presented device includes two layers, each layer consists of graphene pattern on a dielectric. The exploited patterns are periodic arrays of graphene disks, ribbons and continues graphene sheet. Each consisting part is modeled by passive circuit elements and an equivalent impedance is calculated for proposed device. The device is simulated via full wave numerical approach and equivalent circuit model representation. The target frequency operational range is THz while CST and MATLAB software's are involved in simulations.
•Here we proposed a multi layers THz duplexer based on combined graphene patterns.•Conducting THz waves to Output channels via artificial graphene patterns.•The presented device includes two layers, each layer consists of graphene pattern on a dielectric.•The exploited patterns are periodic arrays of graphene disks, ribbons and continues graphene sheet.
This manuscript reports on the optimization of a molecular plating procedure for the production of uniform and homogeneous films of holmium deposited onto gold-plated copper substrate. In particular, ...the effects caused by molecular plating solvents with different vapour pressure on the morphology and stability of the resulting films were investigated, allowing the selection of the optimum solvent. The developed procedure will allow allow the production of sources of holmium ions for the envisaged HOLMES experiment aiming at the direct measurement of the neutrino mass.
•The neutrino mass direct measurement is a paramount objective in contemporary science.•The utilization of a Ho-163 source plays a pivotal role in neutrino mass measurement.•Successful fabrication of a Ho source was achieved through molecular plating method.
The microstructure of grain boundaries (GBs) in the commercial NdFeB-based alloy for permanent magnets has been studied. It is generally accepted that the unique hard magnetic properties of such ...alloys are controlled by the thin layers of a Nd-rich phase in Nd2Fe14B/Nd2Fe14B GBs. These GB layers ensure the magnetic isolation of Nd2Fe14B grains from each other. It is usually supposed that such GB layers contain metallic Nd or Nd-rich intermetallic compounds. However, the commercial NdFeB-based permanent magnets frequently contain a tangible amount of neodymium oxide Nd2O3 at the triple junctions between Nd2Fe14B grains. The goal of this work was to check whether the Nd2Fe14B/Nd2Fe14B GBs could also contain the thin layers of Nd2O3 oxide phase. Indeed, the screening with EELS-based elemental analysis permitted to observe that some of these Nd-rich layers in Nd2Fe14B/Nd2Fe14B GBs contain not only neodymium, but also oxygen. More detailed analysis of such GBs with high-resolution transmission electron microscopy (HR TEM) showed these GB layers are crystalline and have the lattice of neodymium oxide Nd2O3. In turn, the Lorentz micro-magnetic contrast in TEM permitted to observe that the Nd-oxide GB layers prevent the migration of domain walls from one Nd2Fe14B grain to another during remagnetization. This finding proves that the GB oxide layers, similar to those of metallic Nd or Nd-rich intermetallic compounds, can ensure the magnetic isolation between Nd2Fe14B grains needed for high coercivity. Therefore, the GB oxide layers can be used for further development of NdFeB-based permanent magnets.
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•It has been observed that Nd2Fe14B/Nd2Fe14B GBs in the NdFeB-based alloys for permanent magnets can contain Nd2O3 oxide layers.•It has been also shown that Nd2O3 oxide GB layers, similar to GBs with metallic Nd or intermetallic phases, can effectively ensure the magnetic isolation of Nd2Fe14B grains from each other.•Therefore, the GB oxide layers can be used for further development of NdFeB-based permanent magnets.
Nature’s hierarchical materials Fratzl, Peter; Weinkamer, Richard
Progress in materials science,
11/2007, Letnik:
52, Številka:
8
Journal Article
Recenzirano
Odprti dostop
Many biological tissues, such as wood and bone, are fiber composites with a hierarchical structure. Their exceptional mechanical properties are believed to be due to a functional adaptation of the ...structure at all levels of hierarchy. This article reviews the basic principles involved in designing hierarchical biological materials, such as cellular and composite architectures, adapative growth and as well as remodeling. Some examples that are found to utilize these strategies include wood, bone, tendon, and glass sponges – all of which are discussed.
This paper reviews several leading approaches for asymptotic modelling of thin layers in elastostatics and wave propagation phenomena. The issues related to applications of the so-called ‘equivalent’ ...or ‘effective’ boundary conditions and their interpretations are highlighted. Comparative analysis of asymptotic models is performed for a two-dimensional elastostatic case using a novel complex variables-based modelling tool. Its implementation allows for straightforward derivations of higher order boundary conditions for problems with layers of arbitrary sufficiently smooth curvatures. Explicit expressions for the conditions up to the third order are provided. All models are tested using available benchmark solutions and the solutions for the limiting cases of the layer parameters.
This article is part of the theme issue ‘Wave generation and transmission in multi-scale complex media and structured metamaterials (part 1)’.
The Cover Feature shows a newly prepared flavo7helicene 1 that combines inherent helical chirality with redox activity, which was studied in solution (both aqueous and organic phases), in layers ...(electropolymers), and in the solid state (a single crystal). In addition, a methodology that allows the loading of 1 enantiomers into an internally nanostructured lipid 1‐monoolein matrix was developed. More information can be found in the Full Paper by J. Vacek, J. Žádný and co‐workers.
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