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An approach to form planar structures based on ferromagnetic Fe1 − xSix films is presented. Epitaxial Fe1 − xSix iron-silicon alloy films with different silicon content (x = 0-0.4) were grown on Si(111) substrates. Structural in situ and ex situ characterization of the films obtained was made by X-ray diffraction, reflective high-energy electron diffraction, Rutherford backscattering spectrometry and transmission electron microscopy, which confirmed single crystallinity and interface abruptness for all films. Etching rates in the wet etchant (HF: HNO3: H2O = 1: 2: 400) for the films with various chemical composition were obtained. A nonmonotonic dependence of the etching rate on silicon content with a maximum for the composition Fe0.92Si0.08 was discovered. Moreover, the etching process is vertical and selective in the etching solution, i.e., the etching process takes place only in silicide film and does not affect substrate. As an example, a four-terminal planar structure was made of Fe0.75Si0.25/Si(111) structure using the etching rate obtained for this silicon content. Magneto-optical Kerr effect (MOKE) microscopy and transport properties characterization indicated successful etching process.

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Copper-doped titanium oxynitride (TiN x O y ) thin films were grown by atomic layer deposition (ALD) using the TiCl 4 precursor, NH 3 , and O 2 at 420 °C. Forming gas was used to reduce the background oxygen concentration and to transfer the copper atoms in an ALD chamber prior to the growth initiation of Cu-doped TiN x O y . Such forming gas-mediated Cu-doping of TiN x O y films had a pronounced effect on their resistivity, which dropped from 484 ± 8 to 202 ± 4 μΩ cm, and also on the resistance temperature coefficient (TCR), which decreased from 1000 to 150 ppm °C−1 . We explored physical mechanisms causing this reduction by performing comparative analysis of atomic force microscopy, X-ray photoemission spectroscopy, X-ray diffraction, optical spectra, low-temperature transport, and Hall measurement data for the samples grown with and without forming gas doping. The difference in the oxygen concentration between the films did not exceed 6%. Copper segregated to the TiN x O y surface where its concentration reached 0.72%, but its penetration depth was less than 10 nm. Pronounced effects of the copper doping by forming gas included the TiN x O y film crystallite average size decrease from 57−59 to 32−34 nm, considerably finer surface granularity, electron concentration increase from 2.2(3) × 10 22 to 3.5(1) × 10 22 cm −3 , and the electron mobility improvement from 0.56(4) to 0.92(2) cm 2 V −1 s −1 . The DC resistivity versus temperature R(T) measurements from 4.2 to 300 K showed a Cu-induced phase transition from a disordered to semimetallic state. The resistivity of Cu-doped TiN x O y films decreased with the temperature increase at low temperatures and reached the minimum near T = 50 K revealing signatures of the quantum interference effects similar to 2D Cu thin films, and then, semimetallic behavior was observed at higher temperatures. In TiN x O y films grown without forming gas, the resistivity decreased with the temperature increase as R(T) = − 1.88T 0.6 + 604 μΩ cm with no semimetallic behavior observed. The medium range resistivity and low TCR of Cu-doped TiN x O y make this material an attractive choice for improved matching resistors in RF analog circuits and Si complementary metal−oxide−semiconductor integrated circuits.

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Identification of primary tumors and metastasis sites is an essential step in cancer diagnostics and the following treatment. Positron emission tomography-computed tomography (PET/CT) is one of the most reliable methods for scanning the whole organism for malignancies. In this work, we synthesized an 11 C-labeled oligonucleotide primer and hybridized it to an anti-cancer DNA aptamer. The 11 C-aptamer was applied for in vivo imaging of Ehrlich ascites carcinoma and its metastases in mice using PET/CT. The imaging experiments with the 11 C-aptamer determined very small primary and secondary tumors of 3 mm 2 and less. We also compared 11 C imaging with the standard radiotracer, 2-deoxy-2-[fluorine-18]fluoro-Dglucose ( 18 F-FDG), and found better selectivity of the 11 C-aptamer to metastatic lesions in the metabolically active organs than 18 F-FDG. 11 C radionuclide with an ultra-short (20.38 min) half-life is considered safest for PET/CT imaging and does not cause false-positive results in heart imaging. Its combination with aptamers gives us high-specificity and high-contrast imaging of cancer cells and can be applied for PET/CT-guided drug delivery in cancer therapies.

Aptamer selection against novel infections is a complicated and time-consuming approach. Synergy can be achieved by using computational methods together with experimental procedures. This study aims to develop a reliable methodology for a rational aptamer in silico et vitro design. The new approach combines multiple steps: (1) Molecular design, based on screening in a DNA aptamer library and directed mutagenesis to fit the protein tertiary structure; (2) 3D molecular modeling of the target; (3) Molecular docking of an aptamer with the protein; (4) Molecular dynamics (MD) simulations of the complexes; (5) Quantum-mechanical (QM) evaluation of the interactions between aptamer and target with further analysis; (6) Experimental verification at each cycle for structure and binding affinity by using small-angle X-ray scattering, cytometry, and fluorescence polarization. By using a new iterative design procedure, structure-and interaction-based drug design (SIBDD), a highly specific aptamer to the receptorbinding domain of the SARS-CoV-2 spike protein, was developed and validated. The SIBDD approach enhances speed of the high-affinity aptamers development from scratch, using a target protein structure. The method could be used to improve existing aptamers for stronger binding. This approach brings to an advanced level the development of novel affinity probes, functional nucleic acids. It offers a blueprint for the straightforward design of targeting molecules for new pathogen agents and emerging variants.