Search Results (36)

The article is focused on the quantitative assessment of the thermal impact of polar mesospheric clouds (PMCs) on the mesopause caused by the emission of absorbed solar and terrestrial infrared (IR) radiation by cloud particles. For this purpose, a parameterization of mesopause heating by PMC crystals has been developed, the main feature of which is to incorporate the thermal properties of ice and the interaction of cloud particles with the environment. Parametrization is based on PMCs zero-dimensional (0-D) model and uses temperature, pressure, and water vapor data in the 80–90 km altitude range retrieved from Solar Occultation for Ice Experiment (SOFIE) measurements. The calculations are made for 14 PMC seasons in both hemispheres with the summer solstice as the central date. The obtained results show that PMCs can make a significant contribution to the heat balance of the upper atmosphere, comparable to the heating caused, for example, by the dissipation of atmospheric gravity waves (GWs). The interhemispheric differences in heating are manifested mainly in the altitude structure: in the Southern Hemisphere (SH), the area of maximum heating values is 1–2 km higher than in the Northern Hemisphere (NH), while quantitatively they are of the same order. The most intensive heating is observed at the lower boundary of the minimum temperature layer (below 150 K) and gradually weakens with altitude. The NH heating median value is 5.86 K/day, while in the SH it is 5.24 K/day. The lowest values of heating are located above the maximum of cloud ice concentration in both hemispheres. The calculated heating rates are also examined in the context of the various factors of temperature variation in the observed atmospheric layers. It is shown in particular that the thermal impact of PMC is commensurate with the influence of dissipating gravity waves at heights of the mesosphere and lower thermosphere (MLT), which parameterizations are included in all modern numerical models of atmospheric circulation. Hence, the developed parameterization can be used in global atmospheric circulation models for further study of the peculiarities of the thermodynamic regime of the MLT. Full article

The encapsulation of hydrophobic substances remains a significant challenge due to limitations such as low loading efficiency, leakage, and poor distribution within microcapsules. This study introduces a novel strategy utilizing colloidosomes assembled from polyelectrolyte microcapsules (PMCs). PMCs were fabricated via layer-by-layer (LbL) assembly on manganese carbonate (MnCO₃) or calcium carbonate (CaCO₃) cores, followed by core dissolution. A solvent gradient replacement method was employed to substitute the internal aqueous phase of PMCs with kerosene, enabling the formation of colloidosomes through self-assembly upon resuspension in water. Comparative analysis revealed that MnCO₃-based PMCs with smaller diameters (2.5–3 µm vs. 4.5–5.5 µm for CaCO₃) exhibited 3.5-fold greater stability, attributed to enhanced inter-capsule interactions via electrostatic and hydrophobic forces. Confocal microscopy confirmed the structural integrity of colloidosomes, featuring a liquid kerosene core encapsulated within a PMC shell. Temporal stability studies indicated structural degradation within 30 min, though 5% of colloidosomes retained integrity post-water evaporation. PMC-based colloidosomes exhibit significant application potential due to their integration of colloidosome functionality with PMC-derived structural features—semi-permeability, tunable shell thickness/composition, and stimuli-responsive behavior—enabling their adaptability to diverse technological and biomedical contexts. This innovation holds promise for applications in drug delivery, agrochemicals, and environmental technologies, where controlled release and stability are critical. The findings highlight the role of core material selection and solvent engineering in optimizing colloidosome performance, paving the way for advanced encapsulation systems. Full article

In this paper, a series of polyaniline (PANI)/Ti₃C₂ MXene composites (PMCs) with a biomimetic structure were prepared and employed as an anticorrosion coating application. First, the PANI was synthesized by oxidative polymerization with ammonium persulfate as the oxidant. Then, 2D Ti₃C₂ MXene nanosheets were prepared by treating the Ti₃AlC₂ using the optimized minimally intensive layer delamination (MILD) method, followed by characterization via XRD and SEM. Subsequently, the PMC was prepared by the oxidative polymerization of aniline monomers in the presence of Ti₃C₂ MXene nanosheets, followed by characterization via FTIR, XRD, SEM, TEM, CV, and UV–Visible. Eventually, the PMC coatings with the artificial biomimetic surface structure of a macaw feather were prepared by the nano-casting technique. The corrosion resistance of the PMC coatings, evaluated via Tafel polarization and Nyquist impedance measurements, shows that increasing the MXene loading up to 5 wt % shifts the corrosion potential (E_corr) on steel from −588 mV to −356 mV vs. SCE, reduces the corrosion current density (I_corr) from 1.09 µA/cm² to 0.035 µA/cm², and raises the impedance modulus at 0.01 Hz from 67 kΩ to 3794 kΩ. When structured with the hierarchical feather topography, the PMC coating (Bio-PA-MX-5) further advances the E_corr to +103.6 mV, lowers the I_corr to 7.22 × 10⁻⁴ µA/cm², and boosts the impedance to 96,875 kΩ. Compared to neat coatings without biomimetic structuring, those with engineered biomimetic surfaces showed significantly improved corrosion protection performance. These enhancements arise from three synergistic mechanisms: (i) polyaniline’s redox catalysis accelerates the formation of a dense passive oxide layer; (ii) MXene nanosheets create a tortuous gas barrier that cuts the oxygen permeability from 11.3 Barrer to 0.9 Barrer; and (iii) the biomimetic surface traps air pockets, raising the water contact angle from 87° to 135°. This integrated approach delivers one of the highest combined corrosion potentials and impedance values reported for thin-film coatings, pointing to a general strategy for durable steel protection. Full article

The development of a Mach–Zehnder interferometer based on tapered optical fiber for temperature sensing applications is presented. Two tapers, 24 mm apart, were fabricated on SMF-28e+ using the fusion splicer. The optical structures were coated with a 100 nm layer of gold. The influence of the gold deposition on the temperature sensitivity of the fabricated sensors is presented. The sensor was characterized in O-, S-, C-, and L-bands in a temperature range of 0–70 °C. The highest temperature sensitivity of 72 pm/°C with R² = 0.9974 was obtained for the gold-coated sensor. During the investigation, the average transmission loss was low and did not exceed 7 dB. Full article

Lilies are one of the most popular ornamental flowers in the world. However, the abundant pollen produced in their anthers causes significant inconvenience for producers and consumers. Pollen abortion induced by molecular breeding techniques is one of the effective ways to solve this problem. In this study, the LoTDF1 gene, which is involved in regulating lily anther development, was identified and cloned from lily anthers based on transcriptome data. The open reading frame of LoTDF1 is 936 bp and encodes a protein with 311 amino acids. Multiple sequence alignment and phylogenetic tree analysis revealed that the LoTDF1 protein contained a conserved R2R3 domain, belonging to the MYB transcription factor family. Subcellular localization and transcriptional activation assays demonstrated that LoTDF1 localized to the nucleus and functioned as a transcription activator. The transcriptional activation domain was located within the last 195 amino acids (117–311a) of the C-terminus, and there may be more than one transcriptional activation domain in the region. The expression level of the LoTDF1 gene was highest during the pollen mother cell (PMC) stage of lily anther development (2 cm anther), followed by the tetrad stage (4 cm anther). In situ hybridization experiments further confirmed that LoTDF1 transcripts were predominantly localized in PMCs, tapetal cells, middle layer cells, dyads, and tetrads. The experiment data suggest that LoTDF1 plays a critical role in regulating early anther development in lily. LoTDF1 could be a promising candidate gene for molecular breeding strategies aimed at developing pollen-free lily cultivars to enhance commercial and consumer appeal. Full article

TCP transcription factors have long been known to play a crucial role in leaf development, but their significance in reproduction has recently been revealed. TCP5 is a member of class II of the TCP family, which predominantly regulates cell differentiation. This study used overexpression and SRDX fusion to evaluate the role of TCP5 in anther development. TCP5 overexpression resulted in lower fertility, primarily due to anther non-dehiscence. We also observed reduced lignin accumulation in the anther endothecium. In addition, TCP5 overexpression resulted in smaller anthers with fewer pollen sacs and pollen due to early-anther defects before meiosis. TCP5 showed expression in early anthers, including the epidermis, endothecium, middle layer, tapetum, sporogenous cells (pollen mother cells), and vascular bundles. Conversely, during meiosis, the TCP5 signal was only detected in the tapetum, PMCs, and vascular bundles. The TCP5 signal disappeared after meiosis, and no signal was observed in mature anthers. Interestingly, the TCP5-SRDX transgenic plants were also sterile, at least for the early-arising flowers, if not all of them. TCP5-SRDX expression also resulted in undersized anthers with fewer pollen sacs and pollen. However, the lignin accumulation in most of these anthers was comparable to that of the wild type, allowing these anthers to open. The qRT-PCR results revealed that several genes associated with secondary cell wall thickening had altered expression profiles in TCP5 overexpression transgenics, which supported the non-dehiscent anther phenotype. Furthermore, the expression levels of numerous critical anther genes were down-regulated in both TCP5 overexpression and TCP5-SRDX plants, indicating a comparable anther phenotype in these transgenic plants. These findings not only suggest that an appropriate TCP5 expression level is essential for anther development and plant fertility, but also improve our understanding of TCP transcription factor functioning in plant male reproduction and contribute information that may allow us to manipulate fertility and breeding in crops. Full article

Polymer matrix composites (PMCs) often undergo aging as a result of ultraviolet (UV) radiation, which significantly impacts their performance and durability. This paper investigated the alterations in the microstructure and macroscopic properties of epoxy resin and its composite used in overhead wires during UV aging. Furthermore, the mechanism of UV aging for both resin and composite was revealed. The results showed that UV aging predominantly affected the properties of the surface layer resin. UV aging can induce molecular chain scission, which leads to resin weight change, color deepening, microcrack formation, a decline in mechanical properties, and other performance degradation behaviors under the combined action of many factors. With the increase in aging time, the weight change rate and hardness of the resin increased first and then decreased, while the mechanical properties of the composite decreased rapidly first and gradually tended to be constant. The bending strength and impact strength of the composite decreased by 6.0% and 12.8%, respectively, compared with the initial values. The purpose of this study is to comprehensively understand the UV aging behaviors of epoxy resins and their composites employed in overhead wires, and it also provides essential data for advancing the utilization and durability of epoxy resins and composites across aerospace, marine, and other outdoor applications. Full article

In order to solve the problem of flexible sliding tactile composite sensing in the actual grasp of intelligent robot fingers, this paper proposes a research on a convex fiber grating tactile sliding sensor based on mechanical fingers. Based on the sensing principle of fiber Bragg grating, 3D printing technology was used to encapsulate the FBG sensor array with elastic 50 A resin, a double-layer “hemispherical cuboid” distributed sensing unit was designed, and the FBG slippery tactile sensor was actually pasted on the surface of the mechanical finger for static and dynamic experiments. The experimental results show that the slippery tactile sensor designed in this paper has a good linear relationship with temperature and strain. The temperature sensitivities of the polymer-packaged FBGs are $K_{T1}$ = 13.04 pm/°C and $K_{T2}$ = 12.91 pm/°C, and they have a pressure sensitivity of 40.4 pm/N and 31.2 pm/N, respectively. The FBG sliding tactile sensor not only realizes the identification of the sliding signal generation point and the end point but also completes the classification and identification of sandpaper, cardboard, and polypropylene plastic, and it has a high degree of fit with the robot finger, which has certain application value for the intelligent robot sliding tactile signal perception. Full article

This paper presents the study results of formation features of composite hydrogel/polyamide membranes obtained by modification of hydrogel films based on 2-hydroxyethylmethacrylate (HEMA) and polyvinylpyrrolidone (PVP) copolymers. The formation process of composite two-layer membranes was carried out in two stages: obtaining hydrogel membrane substrates followed by their modification with an ultra-thin layer based on a mixture of polyamide (PA) with PVP. The main task of the work was to investigate the possibility of forming a modifying PA/PVP coating on the surface of hydrogel films and to obtain composite hydrogel membranes with the required strength and osmotic permeability based on them. For the formation of composite two-layer membranes, PVP with MM = 12 × 10³ g/mol and MM = 360 × 10³ g/mol were used. Additional use of PVP in the modifying solution contributes to the process of its penetration into the hydrogel substrate. Together with the formation of a reinforcing layer, this ensures the obtainment of hydrogel films of increased strength, with the possibility of directional regulation of their diffusion permeability. It was found that the main factors affecting the nature of the interaction between the layers of the obtained composite films, as well as their physico-mechanical and sorption–diffusion properties, are the HEMA:PVP ratio in the original polymer–monomer composition (PMC), the formulation of the reinforcing layer, the duration of the modification process and the molecular weight of PVP in PMC and in the modifying solution. The strength and water content of two-layer composite hydrogel/polyamide membranes, as well as their salt and water permeability coefficients, are the highest in the case of using high-molecular weight PVP (MM_PVP = 360 × 10³ g/mol) and low-molecular weight (MM_PVP = 12 × 10³ g/mol) during the synthesis of the hydrogel substrate to obtain a PA-6/PVP solution for forming a reinforcing layer. Full article

A new composite material made from mica and a metal–organic framework (MOF) has been developed to improve the anticorrosive capabilities of epoxy resin coatings. The layered mica was loaded with denser and more uniform UIO-66 nanoparticles after modifying the composite with polyethyleneimine (PEI). The composites were used as fillers to prepare epoxy coatings that exhibited long-lasting active (labyrinth effect produced by mica) and passive (pH-sensitive release of corrosion inhibitors) corrosion protection. Settling experiments showed that polyethyleneimine improved the composites’ compatibility in epoxy resin. After being immersed in a 3.5 wt.% NaCl solution for 60 days, the adhesion of PMC–UIO@MBT/EP increases to 9.01 MPa, while the water absorption rate only reaches 2.57%. It indicates that the coating has good barrier properties and stability. After being soaked in a 3.5 wt.% NaCl solution for 60 days at pH = 7, PMC–UIO@MBT/EP exhibits high low-frequency impedance (8.30 × 10⁸ Ω), as demonstrated by the electronic impedance spectrum (EIS). In addition, the coating also exhibited the highest low-frequency impedance after 30 days in 3.5 wt.% NaCl solution at pH = 11. Full article

There are many studies devoted to the application of polyelectrolyte microcapsules (PMC) in various fields; however, there are significantly fewer studies devoted to the study of the polyelectrolyte microcapsules themselves. The study examined the mutual arrangement of the polyelectrolytes in 13-layered PMC capsules composed of (PAH/PSS)₆PAH. The research showed that different layers of the polyelectrolyte microcapsules dissociate equally, as in the case of 13-layered PMC capsules composed of (PAH/PSS)₆PAH with a well-defined shell, and in the case of 7-layered PMC capsules composed of (PAH/PSS)₃PAH, where the shell is absent. The study showed that polyallylamine layers labeled with FITC migrate to the periphery of the microcapsule regardless of the number of layers. This is due to an increase in osmotic pressure caused by the rapid flow of ions from the interior of the microcapsule into the surrounding solution. In addition, FITC-polyallylamine has a lower charge density and less interaction with polystyrene sulfonate in the structure of the microcapsule. Meanwhile, the hydrophilicity of FITC-polyallylamine does not change or decreases slightly. The results suggest that this effect promotes the migration of labeled polyallylamine to a more hydrophilic region of the microcapsule, towards its periphery. Full article

Unidirectional electromagnetic modes have significant potential for routing electromagnetic radiation and are highly desirable for various applications, such as isolators, splitters, and switches. In this study, we theoretically investigate surface magnetoplasmons (SMPs) in a four-layer structure consisting of a perfect magnetic conductor (PMC)–semiconductor–dielectric–metal, which exhibits complete unidirectional propagation. We extend this structure to a 3D model by decreasing the width of the PMC-semiconductor part to an appropriate value and demonstrate that the SMPs in the proposed 3D waveguide retain complete unidirectional propagation. Our findings indicate that the unidirectional SMPs are robust to backscattering caused by surface roughness and defects. Moreover, the proposed 3D waveguide can be efficiently coupled to conventional microstrip line waveguides. Our results (based on the numerical method) demonstrate that SMPs based on semiconductors offer a promising approach to creating devices with new functionalities in the terahertz regime below the diffraction limit. Full article

This article describes a photonic crystal fiber (PCF) temperature sensor that utilizes a flat, metal-coated trapezoidal surface. The PCF is made up of two layers of elliptical air holes and a polished trapezoidal surface that allows temperature sensing. An external sensing approach is used to deposit a thin silver layer on the reflective surface, while a thin SiO₂ film acts as an oxidation-resistant coating. The top elliptical air hole serves as the interface for energy transformation from the core-guided mode to the surface plasmon-polariton (SPP) mode. Simulations carried out using the finite element method indicate that the proposed SPR-PCF temperature sensor can achieve a maximum temperature sensitivity and resolution of up to 5200 pm/°C and 0.01923 °C, respectively, across a temperature range of 10 to 60 °C. This research has significant potential for sensor design and real-time temperature remote sensing applications. Full article

This work details the synthesis and the crystal structures of the quaternary Zintl phases Na₂CaCdSb₂, Na₂SrCdSb₂ and Na₂EuCdSb₂. They are isostructural and their noncentrosymmetric structure is with the space group Pmc2₁ (Pearson code oP12). All structural work is carried out via single-crystal X-ray diffraction methods. The structure features [CdSb₂]^4– layers of corner-shared CdSb₄ tetrahedra, which are stacked along the b-crystallographic axis and are separated by cations. The results from the structure refinements suggest that in addition to full cation ordering, which is typical for this structure, there also exists a possibility for an accommodation of a small degree of cation disorder. Full article

Servers are the infrastructure of enterprise applications, and improving server performance under fixed hardware resources is an important issue. Conducting performance tuning at the application layer is common, but it is not systematic and requires prior knowledge of the running application. Some works performed tuning by dynamically adjusting the hardware prefetching configuration with a predictive model. Similarly, we design a BIOS (Basic Input/Output System)-based dynamic tuning framework for a Taishan 2280 server, including dynamic identification and static optimization. We simulate five workload scenarios (CPU-instance, etc.) with benchmark tools and perform scenario recognition dynamically with performance monitor counters (PMCs). The adjustable configurations provided by Kunpeng processing reach $2^N(N>100)$. Therefore, we propose a joint BIOS optimization algorithm using a deep $Q$-network. Configuration optimization is modeled as a Markov decision process starting from a feasible solution and optimizing gradually. To improve the continuous optimization capabilities, the neighborhood search method of state machine control is added. To assess its performance, we compare our algorithm with the genetic algorithm and particle swarm optimization. Our algorithm shows that it can also improve performance up to 1.10× compared to experience configuration and perform better in reducing the probability of server downtime. The dynamic tuning framework in this paper is extensible, can be trained to adapt to different scenarios, and is more suitable for servers with many adjustable configurations. Compared with the heuristic intelligent search algorithm, the proposed joint BIOS optimization algorithm can generate fewer infeasible solutions and is not easily disturbed by initialization. Full article