Influence of Membrane Stresses on Postbuckling of Rectangular Plates Using a Nonlinear Elastic 3-D Cosserat Brick Element

This paper has two main objectives. The first is to examine the influence of membrane stresses on postbuckled deformations of nonlinear elastic isotropic rectangular plates. The second is to further examine the accuracy of a new 3-D Cosserat eight noded brick element (Nadler and Rubin in Int J Solids Struct 40: 4585–4614, 2003) which was developed within the context of the theory of a Cosserat point. The equations of the Cosserat element include both material and geometric nonlinearities. A number of example problems are considered which examine predictions of the Cosserat element for beams and plates and comparison has been made with results from the commercial codes ANSYS and ADINA. Also, the approximate nonlinear postbuckling solution described in Timoshenko and Gere (Theory of elastic stability, Mc Graw-Hill, New York) is shown to be more limited than originally expected. These results suggest that the Cosserat element is robust, can perform well under extreme conditions and is capable of modeling combinations of three-dimensional bodies with attached thin structures.     

Alcohol oxidase- and formaldehyde dehydrogenase-based enzymatic methods for formaldehyde assay in fish food products

For Gadoid fishes, formaldehyde can be generated in tissues in huge amounts during endogenous enzymatic degradation of natural osmoprotectant trimethylamine-N-oxide. This paper describes two enzymatic methods for assay of formaldehyde in fish food products using alcohol oxidase (AOX) and formaldehyde dehydrogenase (FdDH) isolated from the thermotolerant methylotrophic yeast Hansenula polymorpha. AOX-based method exploits an ability of the enzyme to oxidise a hydrated form of formaldehyde to formic acid and hydrogen peroxide monitored in peroxidase-catalysed colorimetric reaction. In FdDH-based method, a monitored coloured formazane is formed from nitrotetrazolium salt during reduction by NADH, produced in formaldehyde-dependent reaction. It was demonstrated an applicability of both methods for assay of formaldehyde in fish products. The optimal protocols for analysis procedures have been elaborated and analytical parameters of both enzymatic methods have been established. The both methods were demonstrated that some fish products (hake and cod) contain high formaldehyde concentrations (up to 100 mg/kg wet weight).     

Measuring End-to-End Delay in Low Energy SDN IoT Platform

In this paper, we developed a new customizable low energy Software Defined Networking (SDN) based Internet of Things (IoT) platform that can be reconfigured according to the requirements of the target IoT applications. Technically, the platform consists of a set of low cost and energy efficient single-board computers, which are interconnected within a network with the software defined configuration. The proposed SDN switch is deployed on Raspberry Pi 3 board using Open vSwitch (OvS) software, while the Floodlight controller is deployed on the Orange Pi Prime board. We firstly presented and implemented the method for measuring a delay introduced by each component of the IoT infrastructure, ranging from the sensor, the core of SDN, the IoT broker, to an IoT subscriber. Thus, we presented the approach for estimating energy efficiency for SDN based IoT platform proportional to the traffic. The experiments carried out on a real SDN topology based on single-board computers show that our approach not only saves up to 53.56% of energy at low traffic intensity, but also provides QoS guarantee for IoT applications.     

Laccase‐containing ureasil–polymer composite as the sensing layer of an amperometric biosensor

Innovative amperometric biosensors for monitoring the level of wastewater pollution have been constructed on the surface of the gold planar electrodes C220AT “DropSens” by using the organic–inorganic ureasil‐based composites as host matrixes and immobilized commercial laccase from Trametes versicolor . It was found that the biosensor based on the ureasil–chalcogenide glass composite is characterized by a very high sensitivity (67,540 А M^?1 m^?2) that is 38.3 times higher than for pure ureasil (the sensitivity of the bioelectrode was calculated as 1762 А M^?1 m^?2). On the other hand, application of the ureasil–chalcogenide glass composite with incorporated silver nanoparticles (NPs) synthesized by high‐dose (1.0 × 10¹⁷ Ag⁺/cm²) 30 keV Ag⁺ ion implantation results in decreasing the biosensor sensitivity up to 2390 times (the sensitivity of the bioelectrode was 28.3 А M^?1 m^?2). The role of additives (chalcogenide glass and silver NPs) in the ureasil matrix on the biofunctionality of the biosensors produced is considered. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45278.     

Novel plasma treatment in linear antenna microwave PECVD system

This work reports on hydrogen termination of nano-crystalline diamond films and the behavior of polymer SU-8 as passivating layer after plasma treatment performed at low temperature in a novel linear antenna microwave plasma enhanced system. Nano-crystalline diamond films were grown by microwave plasma enhanced chemical vapor deposition and then hydrogen terminated at different substrate temperatures. The results indicate that a temperature as low as 200 °C is sufficient to reliably attain a diamond surface conductivity of the order of 10⁻⁷ (Ω/□)⁻¹. An increase in substrate temperature up to 400 °C results in an increase in surface conductivity up to 1.7 × 10⁻⁶ (Ω/□)⁻¹. The structural changes of the SU-8 passivating layer, before and after plasma treatment, were investigated by FTIR spectroscopy.     

Field-directed self-assembly with locking nanoparticles

A reversible locking mechanism is established for the generation of anisotropic nanostructures by a magnetic field pulse in liquid matrices by balancing the thermal energy, short-range attractive and long-range repulsive forces, and dipole-dipole interactions using a specially tailored polymer shell of nanoparticles. The locking mechanism is used to precisely regulate the dimensions of self-assembled magnetic nanoparticle chains and to generate and disintegrate three-dimensional (3D) nanostructured materials in solvents and polymers.     

Influence of carbon fibre on formation kinetics of crosslinked copolymer from bisphenol A dicyanate and epoxy oligomer

The influence of carbon fibre on the curing kinetics of the prepolymer based on bisphenol A cyanurate and epoxy resin has been studied using infra-red spectroscopy. It was found that the curing process of the prepolymer is very complicated. It is shown that in curing the prepolymer a number of the sequential transformations of one ring structure into others occurs. An introduction of the carbon fibre (CF) of two types, original CF and modified CF (MCF) containing phosphate groups, affects strongly the prepolymer curing. Both CF and MCF accelerate the conversion rate of epoxy groups. In the case of cyanate groups, the former has practically no effect on their conversion whereas the latter decelerates strongly this process. In the present paper the influence of CF on the mechanism of the copolymer formation is considered.     

Integrated thick-film nanostructures based on spinel ceramics

Integrated temperature-humidity-sensitive thick-film structures based on spinel-type semiconducting ceramics of different chemical compositions and magnesium aluminate ceramics were prepared and studied. It is shown that temperature-sensitive thick-film structures possess good electrophysical characteristics in the region from 298 to 358 K. The change of electrical resistance in integrated thick-film structures is 1 order, but these elements are stable in time and can be successfully used for sensor applications.