A CMOS-compatible ISFET with a Ta2O5 sensitive surface was developed. The structure was optimized for achieving high sensitivity using a subthreshold operation mode and by reducing the influence of ...the capacitances on the value of subthreshold swing. The developed ISFET was used as a basis for a biosensor for L-carnitine detection. To this end, carnitine acetyltransferase was immobilized on the ISFET sensitive surface. The immobilized enzyme was active (0.082 U/g model plate). The complete microsystem, consisting of a packaged chip, an immobilized enzyme and a microfluidic channel, detected L-carnitine at a range of 0.2–100 μM with a LOD of 0.2 μM. The biosensor response was linear in the range of 0.2–50 μM of L-carnitine with sensitivity 18.0 ± 1.7 mV/μM. An experiment with artificial urine containing 1.3 μM L-carnitine showed that the proposed biosensor could be used on a real sample. Therefore, a new sensor specially optimized for biosensing CMOS-compatible ISFET structures and direct determination of L-carnitine with immobilized carnitine acetyltransferase was developed.
•A novel CMOS-compatible ISFET was developed and specially optimized for use in subthreshold operation mode.•Carnitine acetyltransferase reaction was directly detected using an electrochemical method for the first time.•The fabricated biosensor allowed detection of L-carnitine in artificial urine.
A biosensor for the direct determination of organophosphorus pesticides (OPs) is described. It utilizes an ion‐selective field‐effect transistor and phosphotriesterase enzyme (PTE), which provides ...cleavage of OPs. The sensitivity of the biosensor was increased after PTE immobilization on the surface of the transistor. Packaging of the integrated circuit and creation of a microfluidic system for analyte delivery stabilized the signal. This system was able to detect 0.1 µM paraoxon and 0.5 µM parathion and methyl parathion and was stable for at least 1 month (PBS, 1°), and could thus provide the basis for a portable device for analyzing OPs in water.
We report the results from the first 5D tomographic diffraction imaging experiment of a complex Ni-Pd/CeO
-ZrO
/Al
O
catalyst used for methane reforming. This five-dimensional (three spatial, one ...scattering and one dimension to denote time/imposed state) approach enabled us to track the chemical evolution of many particles across the catalyst bed and relate these changes to the gas environment that the particles experience. Rietveld analysis of some 2 × 10
diffraction patterns allowed us to extract heterogeneities in the catalyst from the Å to the nm and to the μm scale (3D maps corresponding to unit cell lattice parameters, crystallite sizes and phase distribution maps respectively) under different chemical environments. We are able to capture the evolution of the Ni-containing species and gain a more complete insight into the multiple roles of the CeO
-ZrO
promoters and the reasons behind the partial deactivation of the catalyst during partial oxidation of methane.
The ability to engineer an electronic band structure of topological insulators would allow the production of topological materials with tailor-made properties. Using ab initio calculations, we show a ...promising way to control the conducting surface state in topological insulator based heterostructures representing an insulator ultrathin films on the topological insulator substrates. Because of a specific relation between work functions and band gaps of the topological insulator substrate and the insulator ultrathin film overlayer, a sizable shift of the Dirac point occurs resulting in a significant increase in the number of the topological surface state charge carriers as compared to that of the substrate itself. Such an effect can also be realized by applying the external electric field that allows a gradual tuning of the topological surface state. A simultaneous use of both approaches makes it possible to obtain a topological insulator based heterostructure with a highly tunable topological surface state.
NiPd/Ce sub(0.5)Zr sub(0.5)O sub(2)/Al sub(2)O sub(3) and NiPd/La sub(2)O sub(3)/Ce sub(0.5)Zr sub(0.5)O sub(2)/Al sub(2)O sub(3) catalysts were prepared by incipient wetness co-impregnation method ...or sequential impregnation method for autothermal reforming of methane (ATR of CH sub(4)). The influence of the preparation mode, Ce sub(0.5)Zr sub(0.5)O sub(2) and La sub(2)O sub(3) additives on the physicochemical properties of NiPd supported catalysts and the effect on their activity to produce hydrogen by ATR of CH sub(4) were investigated. Characterization of fresh and spent Ni-based catalysts by X-ray fluorescence spectroscopy, N sub(2) adsorption, X-ray diffraction, H sub(2) temperature-programmed reduction, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy were performed. It was demonstrated that support composition determines NiO dispersion as well as reducibility of Ni species through different strength of Ni-support interaction. The preparation method modifies the phase composition and catalyst ability for reduction. The catalyst evolution under reaction conditions was studied. The NiO ( similar to 15 nm) and NiPd alloy ( similar to 18 nm) phases were observed in the spent catalysts. It was found that the Ni super(o)/NiO ratio can be regulated by support composition and preparation mode of catalysts. It is demonstrated that studied catalysts provide high methane conversion of 90-100%, CO yield of 55-85% and H sub(2) yield of 55-75% in ATR of CH sub(4) at 750-950 degree C. The optimal composition and preparation method of catalyst were selected. The best ATR of CH sub(4) performance is provided by 10 Ni sub(0.5)Pd/10Ce sub(0.5)Zr sub(0.5)O sub(2)/ Al sub(2)O sub(3) catalyst prepared by Pd/Ni sequential impregnation method that can be associated with peculiarity of NiPd particles structure and the optimal ratio between NiO species with different ability for reduction.
A new efficient method is proposed for inducing magnetism on the surface of a topological insulator through the deposition of a thin film of an isostructural magnetic insulator whose atomic ...composition is maximally close to that of the topological material. Such a design prevents the formation of a strong interface potential between subsystems. As a result, the topological state freely penetrates into the magnetic region, where it interacts with the exchange field and gets significantly split at the Dirac point. It is shown that the application of this approach to thin films of a tetradymite-like topological insulator allows realizing the quantum anomalous Hall state with a band gap of several tens of meV.
•The pearlite defect structure under severe plastic deformation is studied.•The formation of ‘channels of deformation’ is detected.•The formation of dynamic recrystallization grains is found.•The ...scalar and excess dislocation densities are estimated.•Their dependences on distance to surface of loading are established.
By the methods of transmission electron microscopy (TEM) at micro- and nanoscale levels the quantitative transformations of structure at a depth of 0, 2, 5, 10 mm along central axis and symmetry axis of fillet head of lengthy differentially quenched rails after severe plastic deformation (passed tonnage of 1770 mln. gross tons) are revealed. At a microscale level the transformation of cementite plates by newly formed grain boundaries absorption of carbon atoms from bulk carbides is established. At a nanoscale level the subgrain structure, being formed in surface layers, contains cementite nanodimensional particles, localized in junctions and along subgrain boundaries. This type of structure was formed as a result of dynamic recrystallization under megaplastic deformation being realized in a process of extremely long-term service of rails. The formation of so-called ‘channels of deformation’ is determined. It is shown that scalar and excess dislocation density in ferrite constituent of steel structure increases as the rail head surface is approached.
We studied structural rearrangement of the myometrium of C57BL/6 mice during the postpartum period under conditions of acute toxic hepatosis induced by CCl
4
injection and its correction with ...immobilized hyaluronidase. In contrast to physiological pregnancy, involution of the myometrium in mice under conditions of acute toxic hepatosis were not completed by the 10th day of the postpartum period. When toxic hepatosis was corrected with immobilized hyaluronidase, the main mechanism of postpartum involution of the mouse myometrium was clasmacytosis, the process of postpartum involution was significantly accelerated, but not completed by the 10th day, probably due to reduced vascularization of the myometrium.
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