The problems of chronic or noncommunicable diseases (NCD) that now kill around 40 million people each year require multiparametric combinatorial diagnostics for the selection of effective treatment tactics. This could be implemented using the biosensor principle based on peptide aptamers for spatial recognition of corresponding protein markers of diseases in biological fluids. In this paper, a low-cost label-free principle of biomarker detection using a biosensor system based on fluorometric registration of the target proteins bound to peptide aptamers was investigated. The main detection principle considered includes the re-emission of the natural fluorescence of selectively bound protein markers into a longer-wavelength radiation easily detectable by common charge-coupled devices (CCD) using a specific luminophore. Implementation of this type of detection system demands the reduction of all types of stray light and background fluorescence of construction materials and aptamers. The latter was achieved by careful selection of materials and design of peptide aptamers with substituted aromatic amino acid residues and considering troponin T, troponin I, and bovine serum albumin as an example. The peptide aptamers for troponin T were designed in silico using the «Protein 3D» (SPB ETU, St. Petersburg, Russia) software. The luminophore was selected from the line of ZnS-based solid-state compounds. The test microfluidic system was arranged as a flow through a massive of four working chambers for immobilization of peptide aptamers, coupled with the optical detection system, based on thick film technology. The planar optical setup of the biosensor registration system was arranged as an excitation-emission cascade including 280 nm ultraviolet (UV) light-emitting diode (LED), polypropylene (PP) UV transparent film, proteins layer, glass filter, luminophore layer, and CCD sensor. A laboratory sample has been created.
Physical mechanisms underlying the multilevel resistive tuning over seven orders of magnitude in structures based on TiO2/Al2O3 bilayers, sandwiched between platinum electrodes, are responsible for the nonlinear dependence of the conductivity of intermediate resistance states on the writing voltage. To improve the linearity of the electric-field resistance tuning, we apply a contact engineering approach. For this purpose, platinum top electrodes were replaced with aluminum and copper ones to induce the oxygen-related electrochemical reactions at the interface with the Al2O3 switching layer of the structures. Based on experimental results, it was found that electrode material substitution provokes modification of the physical mechanism behind the resistive switching in TiO2/Al2O3 bilayers. In the case of aluminum electrodes, a memory window has been narrowed down to three orders of magnitude, while the linearity of resistance tuning was improved. For copper electrodes, a combination of effects related to metal ion diffusion with oxygen vacancies driven resistive switching was responsible for a rapid relaxation of intermediate resistance states in TiO2/Al2O3 bilayers.
Test results of axial shift of “technical ceramics - glass” parts in taper interference fit joint under axial loading are presented. The load-carrying capacity was tested under normal conditions; a servo press was used to load the test samples. The tested samples were assembled by thermal method.
In modern nanoelectronics, the density of transis tors arranged on a chip has reached a high level such that a key problem of further development of integra tion is related not as much to the transistor physics as to the conditions of signal transfer in the scheme, since the spacing of conductors is small so that the unavoid able parasitic capacitance between them significantly retards the signal propagation [1]. In addition, the level of power dissipation due to leakage currents and dynamic scattering (proportional to the parasitic capacitance) has also increased. In order to solve this problem, it is necessary to possible reduce the parasitic capacitance, which can be achieved by radically decreasing the dielectric permittivity of an insulator on which the electric connections are supported.An optimum solution of this task would be the introduction of pores into the insulator-in particu lar, into a silica substrate [2]. Since porous silica (por SiO 2 ) is a new material, it is necessary to develop a cor responding special technology of growing thin films on these substrates. As is known [3,4], the properties of thin films strongly depend on both the material and surface state of a substrate. In this context, the present investigation was aimed at studying the influence of porosity on the structure of thin films synthesized on por SiO 2 substrates using the example of thin alumina (Al 2 O 3 ) films of various thicknesses grown by atomic layer deposition (ALD). Alumina was selected to be the film material because (i) this compound remains chemically stable during deposition onto various sub strates and (ii) the technology of Al 2 O 3 synthesis on traditional substrates is well developed and gives repro ducible results. For comparison, we have also studied alumina films grown on crystalline silicon (c Si) and those covered by a thermal SiO 2 layer.The porous silica substrates were prepared from a liquid phase using the spin coating technique followed by drying in an infrared furnace. The average pore size in as prepared samples was about 2 nm. Alumina films were synthesized by ALD on these por SiO 2 substrates at a temperature of 280°C. The ALD cycle consisted of two steps, in which the precursors were trimetylalumi num Al(CH 3 ) 3 and water vapor at a reactant tempera ture of 22°C.The samples were studied by X ray reflection spec troscopy using s polarized synchrotron radiation. The measurements were performed on a Reflectometer setup of D 08 1B2 Optics Beamline at BESSY II [5, 6]. The energy resolution at 85 eV (near the AlL 2,3 absorption edge) was better than 20 meV, and the accuracy of photon energy determination was about 10 meV. The reflected signal was detected by a GaAsP Schottky diode and a Keithley 617 electrometer. A total working diode area of 4 × 4 mm 2 allowed the entire reflected beam to be detected. The measured reflection spectra were used to calculate the spectra of absorption based on the Kramers-Kronig relation and a method that has been described in detail elsewhere [7]. Figure 1a shows the ...
Abstract. The paper presents the results of investigation of cyclone impact on ionosphere parameters. Ionosphere state was observed by automatic sounding equipment applying low-orbital navigation spacecrafts in the conditions of low seismicity.
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