On the bifurcations of the Lamé solutions in plane-strain elasticity

We consider the in-plane bifurcations experienced by the Lamé solutions corresponding to an elastic annulus subjected to radial tension on the curved boundaries. Numerical investigations of the relevant incremental problem reveal two main bifurcation modes: a long-wave local deformation around the central hole of the domain, or a material wrinkling-type instability along the same boundary. Strictly speaking, the latter scenario is related to the violation of the Shapiro–Lopatinskij condition in an appropriate traction boundary-value problem. It is further shown that the main features of this material instability mode can be found by using a singular-perturbation strategy.     

Dependence of adenine isolation efficiency on the chain length evidenced using paramagnetic particles and voltammetry measurements

The main aim of this work was to study the dependence of oligoadenine isolation efficiency on the chain length by using paramagnetic particles covered by homo-deoxythymidines ((dT)25) with subsequent detection by adsorptive transfer technique coupled with square wave voltammetry. For this purpose, the oligonucleotides of the length A5, A10, A15, A20, A25, A30, A35, A40 and poly(A) in various concentrations were chosen. We determined that the isolation efficiency defined as “isolated oligonucleotide concentration”/“given oligonucleotide concentration” was about 55% on average. Sequence A25 demonstrated the best binding onto microparticles surface.     

The effect of silicon substrate on thickness of SiO2 thin film analysed by spectral reflectometry and interferometry

Techniques of spectral reflectometry and interferometry are used for measuring small changes in thickness of SiO₂ thin film grown by thermal oxidation on different silicon substrates. A slightly dispersive Michelson interferometer with one of its mirrors replaced by a thin-film structure is used to measure the reflectance and interferometric phase of the thin-film structure at the same time. The experimental data are used to determine precisely the thickness of the SiO₂ thin film on silicon wafers of two crystallographic orientations and different dopant concentrations. We confirmed very good agreement between the experimental data and theory and revealed that the thin-film thickness, which varies with the type of silicon substrate, depends linearly on the wavelength at which minimum in the spectral reflectance occurs. Similar behaviour was revealed for the interferometric phase.     

Lessons from the first international proficiency test for the detection of spores from the honey bee pathogen Paenibacillus larvae

We report on the first proficiency test in the context of honey bee disease testing on a broad international scale. Honey samples were distributed to 12 participating laboratories for isolation and identification of spores of the etiological agent of American foulbrood, Paenibacillus larvae. Of the 11 laboratories responding to this proficiency testing event, only 6 (54%) provided data that were in full agreement with the previously determined status of the honey samples; eight (72%) laboratories fell within the threshold for qualification as defined a priori in this proficiency test (=level of agreement of at least 90%). Some lessons can now be drawn from the organizational point of view and will certainly improve new initiatives to be taken.     

Automated nucleic acids isolation using paramagnetic microparticles coupled with electrochemical detection

Easy, efficient and low demanding separation of mRNA from biological material is needed to study gene expression and to use in chip technologies. It is common knowledge that each mRNA molecule contains sequence of 25 adenines. This feature can be used for binding mRNA on the surface of the particles coated by thymine chains. The present work reports on suggesting and optimizing of mRNA separation and detection from biological material via paramagnetic microparticles coupled with electrochemical detection. Primarily we optimized cyclic and square wave voltammetric conditions to detect poly(A), which was used as standard to mimic behaviour of mRNA. Under the optimized square wave voltammetric conditions (frequency 280 Hz, accumulation time 200 s, supporting electrolyte and its temperature: acetate buffer 4.6 and 35 °C) we estimated detection limit down to 1 ng of poly(A) per ml. To enhance effectiveness and repeatability of isolation of nucleic acid automated approach for rinsing and hybridizing was proposed. We optimized the whole procedure and experimental conditions. Using automated way of isolation and under optimized conditions the yield of poly(A) (isolated concentration of poly(A)/given concentration of poly(A)*100) was approximately 75%. The suggested and optimized method for poly(A) isolation and detection was utilized for the analysis of brain tissues of patients with traumatic brain injury. The total amount of isolated mRNA varied from 40 to 760 g of mRNA per g of brain tissue. The isolation of mRNA from six samples per run was not longer than 2.5 h. Moreover, we applied the optimized procedure on fully automated pipetting instrument to isolate mRNA. The instrument was successfully tested on the analysis of extracts from roots of maize plants treated with cadmium(II) ions.     

Robust stabilization of a chemical reactor

Robust static output feedback control was applied to a continuous stirred tank reactor with parametric uncertainty and multiple steady states in which exothermic reaction takes place. The problem of robust controller design was converted to a solution of linear matrix inequalities and a computationally simple non-iterative algorithm is presented. The possibility of using robust static output feedback for stabilization of reactors with uncertainty and comparison of robust P and PI controllers with an optimal controller is demonstrated by simulation results.     

On an Inviscid Model for Incompressible Two-Phase Flows with Nonlocal Interaction

We consider a diffuse interface model which describes the motion of an ideal incompressible mixture of two immiscible fluids with nonlocal interaction in two-dimensional bounded domains. This model consists of the Euler equation coupled with a convective nonlocal Cahn-Hilliard equation. We establish the existence of globally defined weak solutions as well as well-posedness results for strong/classical solutions.     

Peroxide-based route assisted with inverse microemulsion process to well-dispersed Bi<Subscript>4</Subscript>Ti<Subscript>3</Subscript>O<Subscript>12</Subscript> nanocrystals

Well-dispersed bismuth titanate (BIT) nanocrystals with an average size ranged from 3 to 60 nm were synthesized via a peroxide-based route assisted with an inverse microemulsion process. The crystallite size and lattice parameter of BIT upon variable-temperature were determined by X-ray diffraction (XRD). The particle size was confirmed by transmission electron microscopy (TEM). Thermal decomposition behaviour of Ti-peroxy and BIT gel and crystallization kinetics of BIT nanocrystals were investigated by differential scanning calorimetry/thermogravimetry (DSC/TG) and Fourier-Transform infrared spectroscopy (FTIR). Analysis of nonisothermal DSC data yielded a value of 220.84 ± 2.73 KJ/mol and 2.25 ± 0.26 for the activation energy of crystallization (E _a) and the Avrami exponent (n), respectively.     

Boson Nebulae Charge

We use the first-order approximate solutions to the nonlinear system of Klein-Gordon-Maxwell-Einstein equations describing the minimally coupled charged spin-less field to a spherically symmetric spacetime to analyze a becoming boson star. In the far future and long-range approximation, we derive an analytical time-dependent charge which allows us to point out several significant moments in the evolution of the boson nebula.     

Disposable Biosensor Based on Amidase/CeO2/GNR Modified Inkjet‐printed CNT Electrodes‐droplet Based Paracetamol Detection in Biological Fluids for “Point‐of‐care” Applications

A disposable acetaminophen biosensor based on inkjet‐printed CNT electrodes (IJPCNT) modified with amidase/cerium dioxide@graphene nanoribbons composite was developed (ACeO2@GNR/IJPCNT). The enzyme amidase A was used for the first time as a recognition element. Inkjet‐printed CNT electrodes served as a basis for the construction of a biosensor that enables droplet detection using 5 μL sample volume. The biosensor showed high selectivity, sensitivity, a low detection limit of 0.18 μM and a wide working linear range from 1 to 100 μM. The proposed approach allows fast and reliable detection of acetaminophen in biological fluids with negligible matrix effect and remarkable reproducibility.