Exploiting Localized Surface Plasmon Resonances in Subwavelength Spiral Disks for THz Thin Film Sensing

In this paper, we studied the sensing performance of metasurfaces comprised by spiral-disk-shaped metallic elements patterned on polypropylene substrates, which exhibited localized surface plasmon resonances in the low-frequency region of the terahertz (THz) spectrum (0.2–0.5 THz). Optimal designs of spiral disks with C-shaped resonators placed near the disks were determined and fabricated. The experimentally measured transmittance spectra of the samples coated with very thin photoresistive layers (d ~ 10−4–10−3 λ) showed good agreement with the simulations. The resonance frequency shift Δf increases with increasing d, while saturating near d = 50 µm. The narrow-band magnetic dark modes excited on symmetrical spiral disks with a 90° C-resonator demonstrated very high figure of merit (FOM) values reaching 1670 (RIU·mm)−1 at 0.3 μm thick analyte. The hybrid high order resonances excited on asymmetrical densely packed spiral disks showed about two times larger FOM values (up to 2950 (RIU·mm)−1) compared to symmetrical distantly spaced spirals that resembled the best FOM results found in the literature for metasurfaces fabricated with a similar technique. The demonstrated high sensing performance of spiral disks is evaluated to be promising for bio-sensing applications in the THz range

Modeling of ignition and combustion of boron-containing solid propellants

This paper presents the results of an experimental study of the ignition and slagging characteristics for combustion of boron-containing solid propellants with ammonium perchlorate as an oxidizer under conditions modeling the operation of the gas generator and afterburner of a rocket-rarnjet engine. It is shown that the introduction of fluorine-containing additives into the propellant reduces the content and adhesion capacity of primary condensed combustion products (slags). The dependences of the ignition delay on the radiant heat flux density in the range 20-180 W /cm2 are obtained for model solid propellants containing boron, carbon, boron carbide, and slag particles collected in the gas generator

Features of organotopic remodeling of bone tissue and implanted osteoplastic material in Charcot neuro/osteoarthropathy

Introduction Despite the recognition of MRI as the gold diagnostic standard for Charcot arthropathy, there is evidence in the literature that MSCT is more informative for objective qualitative and quantitative diagnosis of the condition, primarily of the bone skeleton of the Charcot foot, in comparison with standard radiography. The sensitivity and specificity of these methods are different. Purpose To reveal the features of organotopic remodeling of bone tissue and implanted osteoplastic material in the course of midfoot and hindfoot subtotal defects management in Charcot neuro-osteoarthropathy. Materials and methods The analysis of bone tissue and implanted osteoplastic material density was carried out in a case series that included 11 patients with Charcot neuro-osteoarthropathy who underwent a two‑stage procedure for bone defects in the hindfoot and midfoot with the Ilizarov apparatus. We studied CT and MRI scans and measured bone regenerate density before treatment, at the stages of transosseous osteosynthesis, and 3, 6, and 12 months after surgery. Results In all patients, varying increase in the amount and volume of bone tissue was visualized due to intensive periosteal bone formation along with the formation of bone ankylosis in the joints along combined with a consistent increase in the optical density of bone regenerates. The formation of the new bone tissue ran without the signs of lysis or sequestration. The conducted studies indicate that the sizes and architectonics of bone fragments are more differentiated in CT than in MRI scans. Discussion It is known that the bone, despite its high mineralization, continuously rebuilds, restores and adapts itself to certain functional conditions. This constant dynamic process of adaptive remodeling depends mostly on optimal blood supply, metabolic activity and the coordinated work of bone cell elements. The data obtained show angiogenesis in the compromised tissues in patients with Charcot foot and consistent remodeling of the graft into the new bone tissue. Conclusion The allobone in the composition of the combined bone graft does not reduce the likelihood of complete remodeling of the newly formed bone tissue. Higher bone density by filling in a bone defect with a graft differs from distraction regenerate that initially has low bone density. CT and MRI are highly effective and informative diagnostic methods for surgical treatment. In reconstructive interventions in the patients with Charcot foot under the conditions of transosseous osteosynthesis, preference among radiological study methods should be given to CT

Oxime Therapy for Brain AChE Reactivation and Neuroprotection after Organophosphate Poisoning

One of the main problems in the treatment of poisoning with organophosphorus (OPs) inhibitors of acetylcholinesterase (AChE) is low ability of existing reactivators of AChE that are used as antidotes to cross the blood-brain barrier (BBB). In this work, modified cationic liposomes were developed that can penetrate through the BBB and deliver the reactivator of AChE pralidoxime chloride (2-PAM) into the brain. Liposomes were obtained on the basis of phosphatidylcholine and imidazolium surfactants. To obtain the composition optimized in terms of charge, stability, and toxicity, the molar ratio of surfactant/lipid was varied. For the systems, physicochemical parameters, release profiles of the substrates (rhodamine B, 2-PAM), hemolytic activity and ability to cause hemagglutination were evaluated. Screening of liposome penetration through the BBB, analysis of 2-PAM pharmacokinetics, and in vivo AChE reactivation showed that modified liposomes readily pass into the brain and reactivate brain AChE in rats poisoned with paraoxon (POX) by 25%. For the first time, an assessment was made of the ability of imidazolium liposomes loaded with 2-PAM to reduce the death of neurons in the brains of mice. It was shown that intravenous administration of liposomal 2-PAM can significantly reduce POX-induced neuronal death in the hippocampus

Modulating the Inclusive and Coordinating Ability of Thiacalix[4]arene and Its Antenna Effect on Yb³-Luminescence via Upper-Rim Substitution<xref rid="fn+-20221012160304-1908848" ref-type="fn">+</xref>

The present work introduces the series of thiacalix[4]arenes (H4L) bearing different upper-rim substituents (R = H, Br, NO2) for rational design of ligands providing an antenna-effect on the NIR Yb3+-centered luminescence of their Yb3+ complexes. The unusual inclusive self-assembly of H3L− (Br) through Brπ interactions is revealed through single-crystal XRD analysis. Thermodynamically favorable formation of dimeric complexes [2Yb3+:2HL3−] leads to efficient sensitizing of the Yb3+ luminescence for H4L (Br, NO2), while poor sensitizing is observed for ligand H4L (H). X-ray analysis of the single crystal separated from the basified DMF solutions of YbCl3 and H4L(NO2) has revealed the transformation of the dimeric complexes into [4Yb3+:2L4−] ones with a cubane-like cluster structure. The luminescence characteristics of the complexes in the solutions reveal the peculiar antenna effect of H4L(R = NO2), where the triplet level at 567 nm (17,637 cm−1) arisen from ILCT provides efficient sensitizing of the Yb3+ luminescence

The Proterozoic evolution of northern Siberian Craton margin: a comparison of U–Pb–Hf signatures from sedimentary units of the Taimyr orogenic belt and the Siberian platform

Identifying the cratonic affinity of Neoproterozoic crust that surrounds the northern margin of the Siberian Craton (SC) is critical for determining its tectonic evolution and placing the Craton in Neoproterozoic supercontinental reconstructions. Integration of new U–Pb–Hf detrital zircon data with regional geological constraints indicates that distinct Neoproterozoic arc-related magmatic belts can be identified within the Taimyr orogen. Sedimentary rocks derived from 970 to 800 Ma arc-related suites reveal abundant Archean and Paleoproterozoic detritus, characteristic of the SC. The 720–600 Ma arc-related zircon population from the younger Cambrian sedimentary rocks is also complemented by an exotic juvenile Mesoproterozoic zircon population and erosional products of older arc-related suites. Nonetheless, numerous evidences imply that both arcs broadly reworked Siberian basement components. We suggest that the early Neoproterozoic (ca. 970–800 Ma) arc system of the Taimyr orogen evolved on the active margin of the SC and probably extended along the periphery of Rodinia into Valhalla orogen of NE Laurentia. We also suggest the late Neoproterozoic (750–550 Ma) arc system could have been part of the Timanian orogen, which linked Siberia and Baltica at the Precambrian/Phanerozoic transition