201 research outputs found

    Long-chain alkyl esters of O,O-dialkyl dithiophosphoric and thionophosphoric acids prepared on the basis of red phosphorus, elemental sulfur, alcohols, and industrial fractions of higher monoolefins

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    Copyright © Taylor & Francis Group, LLC. Mixtures of long chain S-alkyl O,O-dialkyl dithiophosphates, and O-alkyl O,O-dialkyl thionophosphates were obtained by the reaction of red phosphorus with elemental sulfur, alcohols, and industrial fractions of C16-C18 and C20-C26 of higher olefins in the presence of Lewis acid catalysts. The products obtained possess high anticorrosion activities toward mild steel

    Chitosan-Based Polyelectrolyte Complex in Combination with Allotropic Forms of Carbon as a Basis for Thin-Film Organic Electronics

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    Received: 30.05.2024. Revised: 11.06.2024. Accepted: 19.06.2024. Available online: 28.06.2024.Samples of a new polymer composite material based on a PEC doped with various allotropic forms of carbon were prepared.Based on the films studied, field-effect transistors were created and their output and transfer characteristics were measured.If a combination of both GO and SWCNT is incorporated into the nanocomposite, the mobility of carriers increases sharply.Using atomic force microscopy, scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy, the morphology and mobility of charge carriers in composite films with a thickness of no more than 500 nm obtained on the basis of a polyelectrolyte complex of chitosan and chitosan succinamide with addition of particles of carbon materials were studied and estimated. The following carbon materials were used: single-walled carbon nanotubes, graphene oxide, and carbon-containing sorbents with different specific surfaces (Carboblack C and Carbopack). Moreover, the studied materials in the form of films were used as a transport layer in the structure of field-effect transistors. The output and transfer characteristics of the transistors obtained were measured. According to the measurement results, the mobility of charge carriers, μ, ranges from 0.341 to 1.123 cm2 V–1·s–1, depending on the type of carbon material added. The best result was demonstrated by films based on a composite containing simultaneously single-walled carbon nanotubes and graphene oxide (μ = 10.972 cm2 V–1·s–1).This work was supported by the Ministry of Science and Higher Education of the Russian Federation (scientific code FZWU-2023-0002) and by the Russian Science Foundation (Grant № 23-73-00119), https://rscf.ru/project/23-73-00119/

    Chiral Salts of Phosphorus Dithioacids Based on Quinine

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    © 2018, Pleiades Publishing, Ltd. Reactions of quinine with dithioacids based on (1R)-endo-(+)-fenchol, (1S)-endo-(–)-borneol, and (S)-(–)-menthol have afforded optically active quinine salts. Chiral diquinine salts have been obtained in the reactions of quinine with bisthiophosphonic acids based on triethylene glycol and resorcinol

    The influence of restricted geometry of diamagnetic nanoporous media on 3He relaxation

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    © 2015 AIP Publishing LLC. This is an experimental study of the spin kinetics of 3He in contact with diamagnetic samples of inverse opals SiO2, and LaF3 nanopowder. It is demonstrated that the nuclear magnetic relaxation of the absorbed 3He occurs due to the modulation of dipole-dipole interaction by the quantum motion in the two-dimensional film. It is found that the relaxation of liquid 3He occurs through a spin diffusion to the absorption layer, and that the restricted geometry of diamagnetic nanoporous media has an influence on the 3He relaxation

    High-sensitivity diamond magnetometer with nanoscale resolution

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    We present a novel approach to the detection of weak magnetic fields that takes advantage of recently developed techniques for the coherent control of solid-state electron spin quantum bits. Specifically, we investigate a magnetic sensor based on Nitrogen-Vacancy centers in room-temperature diamond. We discuss two important applications of this technique: a nanoscale magnetometer that could potentially detect precession of single nuclear spins and an optical magnetic field imager combining spatial resolution ranging from micrometers to millimeters with a sensitivity approaching few femtotesla/Hz1/2^{1/2}.Comment: 29 pages, 4 figure

    Electron spin as a spectrometer of nuclear spin noise and other fluctuations

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    This chapter describes the relationship between low frequency noise and coherence decay of localized spins in semiconductors. Section 2 establishes a direct relationship between an arbitrary noise spectral function and spin coherence as measured by a number of pulse spin resonance sequences. Section 3 describes the electron-nuclear spin Hamiltonian, including isotropic and anisotropic hyperfine interactions, inter-nuclear dipolar interactions, and the effective Hamiltonian for nuclear-nuclear coupling mediated by the electron spin hyperfine interaction. Section 4 describes a microscopic calculation of the nuclear spin noise spectrum arising due to nuclear spin dipolar flip-flops with quasiparticle broadening included. Section 5 compares our explicit numerical results to electron spin echo decay experiments for phosphorus doped silicon in natural and nuclear spin enriched samples.Comment: Book chapter in "Electron spin resonance and related phenomena in low dimensional structures", edited by Marco Fanciulli. To be published by Springer-Verlag in the TAP series. 35 pages, 9 figure

    Efficacy and tolerability of adalimumab (humira) in patients with active rheumatoid arthritis

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    Objective: to evaluate the efficacy and tolerability of adalimumab alone and in combination with basic anti-inflammatory drugs (BAIDs) in patients with rheumatoid arthritis (RA), by taking into account the specific features of the course of the disease. Subjects and methods. The study enrolled 30 patients with a verified diagnosis of RA, its high activity by DAS 28, and ineffective previous therapy with standard BAIDs. At the beginning of the study, 20 (66.7%) patients continued taking BAIDs. According to therapy, the patients were divided into 3 groups: 1) 10 (33.3%) patients received subcutaneous adalimumab injections only; 2) 12 (40%) took adalimumab+methotrexate (MT); 3) 8 (26.7%) had adalimumab+leflunomide. The patient groups were matched for age, the duration and activity of RA (by DAS 28), its X-ray stage and seropositivity. Nine (37.5%) patients took oral glucocorticoids (GCs) and 25 (83.3%) received non-steroidal anti-inflammatory drugs (NSAIDs). Two (8.3%) patients had previously been prescribed biological therapies. Adalimumab was subcutaneously injected every 2 weeks for 24 weeks. The quantitative parameters of articular syndrome and blood and urine biochemical and clinical analyses were used to evaluate therapeutic effectiveness. The effect of therapy was evaluated by the ACR and EULAR (DAS 28) criteria. The efficiency of therapy was evaluated 12 and 24 weeks after therapy. Results. The clinical and laboratory effect of adalimumab was noted in 29 (96.7%) of the 30 patients. All the assessed parameters of articular syndrome became significantly lower (p<0.001) by week 12 of therapy and to a greater extent by week 24. Evaluation of the efficiency of adalimumab therapy by the ACR criteria showed that following 12-week therapy, the parameters were decreased by 20% in 87% of the patients and 50% in 16.7%; after 24 weeks, 23.3, 70 and 96.7% achieved very good (ACR 70), good (ACR 50), and satisfactory (ACR 20) effects. Estimation of the time course of changes in the disease activity index (DAS 28) revealed that adalimumab significantly reduced disease activity. Therapeutic effectiveness was also shown as reduced needs for NSAIDs and GCs. Positive clinical and laboratory changes during adalimumab+ MT combination therapy were also demonstrated to be significantly higher than those during adalimumab monotherapy or adalimumab + leflunomide combination therapy. Conclusion. Adalimumab is an effective disease-modifying biological agent. Its benefits may include the rapid development (on days 4-5 on average) and long retention (for 6 months or more) of an effect, a good safety profile (adverse reactions occurred only in 16.7% of the patients), and easiness-to-use

    Electron Spin-Relaxation Times of Phosphorus Donors in Silicon

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    Pulsed electron paramagnetic resonance measurements of donor electron spins in natural phosphorus-doped silicon (Si:P) and isotopically-purified 28Si:P show a strongly temperature-dependent longitudinal relaxation time, T1, due to an Orbach process with DeltaE = 126 K. The 2-pulse echo decay is exponential in 28Si:P, with the transverse relaxation (decoherence) time, T2, controlled by the Orbach process above ~12 K and by instantaneous diffusion at lower temperatures. Spin echo experiments with varying pulse turning angles show that the intrinsic T2 of an isolated spin in 28Si:P is ~60 ms at 7 K.Comment: Submitted to PRL on 02.28.200

    Electron spin coherence exceeding seconds in high purity silicon

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    Silicon is undoubtedly one of the most promising semiconductor materials for spin-based information processing devices. Its highly advanced fabrication technology facilitates the transition from individual devices to large-scale processors, and the availability of an isotopically-purified 28^{28}Si form with no magnetic nuclei overcomes what is a main source of spin decoherence in many other materials. Nevertheless, the coherence lifetimes of electron spins in the solid state have typically remained several orders of magnitude lower than what can be achieved in isolated high-vacuum systems such as trapped ions. Here we examine electron spin coherence of donors in very pure 28^{28}Si material, with a residual 29^{29}Si concentration of less than 50 ppm and donor densities of 10141510^{14-15} per cm3^3. We elucidate three separate mechanisms for spin decoherence, active at different temperatures, and extract a coherence lifetime T2T_2 up to 2 seconds. In this regime, we find the electron spin is sensitive to interactions with other donor electron spins separated by ~200 nm. We apply a magnetic field gradient in order to suppress such interactions and obtain an extrapolated electron spin T2T_2 of 10 seconds at 1.8 K. These coherence lifetimes are without peer in the solid state by several orders of magnitude and comparable with high-vacuum qubits, making electron spins of donors in silicon ideal components of a quantum computer, or quantum memories for systems such as superconducting qubits.Comment: 18 pages, 4 figures, supplementary informatio
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