Specific Properties Research Articles

Strain-Induced Frequency Splitting in PT Symmetric Coupled Silicon Resonators.

When two resonators of coupled silicon resonators are identical and the gain on one side is equal to the loss on the other side, a parity-time (PT) symmetric-coupled silicon resonator is formed. As non-Hermitian systems, the PT-symmetric systems have exhibited many special properties and interesting phenomena. This paper proposes the strain-induced frequency splitting in PT symmetry-coupled silicon resonators. The frequency splitting of the PT system caused by strain perturbations is derived and simulated. Theory and simulation both indicate that the PT system is more sensitive to strain perturbation near the exceptional point (EP) point. Then, a feedback circuit is designed to achieve the negative damping required for PT symmetry. Based on a simple silicon-on-insulator (SOI) process, the silicon resonator chip is successfully fabricated. After that, the PT-symmetric-coupled silicon resonators are successfully constructed, and the frequency splitting phenomenon caused by strain is observed experimentally.

Atomistic understanding on the surface formation mechanism of nanoscale scratches along different crystal orientations of silicon carbide

Single crystal silicon carbide has been widely used in many fields due to its excellent physical and chemical properties. However, these special properties of silicon carbide can lead to surface defects and subsurface damage in precision machining processes. In this research, high-speed scratching experiments and molecular dynamics simulations were used to study the surface formation mechanism of nanoscale scratches along the [1-210] and [1-100] crystal orientations of silicon carbide. For both the simulations and experiments, different scratching crystal orientations result in the formation of different amorphous patterns. The angle between the scratching orientation [1-210] and the amorphous pattern is 60°, while the angle between scratching orientation [1-100] and the amorphous pattern is 30°. The stress concentration during the scratching process along the orientations [1-210] and [1-100] is mainly located at the two edges and one edge of the amorphous patterns, respectively. The amorphous patterns along the < 1-210 > directions on the (0001) plane are caused by dislocations and slips on the {10-10} plane. This study reveals the material deformation mechanism and removal mechanism of silicon carbide along different crystal orientations scratching, providing theoretical guidance for the nanoscale machining of silicon carbide.

Dual Frequency-Regulated Magnetic Vortex Nanorobots Empower Nattokinase for Focalized Microvascular Thrombolysis.

Magnetic nanorobots are emerging players in thrombolytic therapy due to their noninvasive remote actuation and drug loading capabilities. Although the nanorobots with a size under 100 nm are ideal to apply in microvascular systems, the propulsion performance of nanorobots is inevitably compromised due to the limited response to magnetic fields. Here, we demonstrate a nattokinase-loaded magnetic vortex nanorobot (NK-MNR) with an average size around 70 nm and high saturation magnetization for mechanical propelling and thermal responsive thrombolysis under a magnetic field with dual frequencies. The nanorobots are stable in suspension and undergo the magneto-steered assembly into chain-like NK-MNRs, which are regulated to generate magnetic forces to mechanically damage and penetrate the thrombus by the low-frequency rotating magnetic field. Synergistically, enhanced magnetic hyperthermia is triggered by an alternating magnetic field of high frequency, enabling heat-induced NK release and fibrinolysis. In this dual frequency-regulated magnetothrombolysis (fRMT) strategy, nanorobots collaborate under the dual magnetic energy conversion model to achieve the vasculature recanalization rate of 81.0% in thrombotic mice. Overall, the nanorobot with the special magnetic vortex property and multimodel controls is a promising nanoplatform for in vivo focalized microvascular thrombolysis.

Barrel rifling node offset detection and subsequent optimization based on thin film in-mold decoration characteristics of the Johnson–Cook model

In this paper, a nodal detection method for the detection and optimization of barrel helix offsets is proposed. The barrel used in this experiment is a 6-helix barrel. Moreover, the special properties of the film of Polyetheretherketone (PEEK) material are used to cover the surface of the barrel helix with a virtual in-mold decoration (IMD) film, and the unique nature of the film die offset in the IMD is utilized to detect the position of the barrel helix. The area with a large die index is the area with a large helix offset in the barrel, and the IMD die index is introduced to quantify the data. The IMD die index is used to determine the helix offset of the damaged barrel. The novelty of this work is that each node can use the die index to efficiently detect the position of the barrel helix deviation, carry out subsequent optimization and repair work through the optimization of the injection molding parameters and the design optimization of the barrel and verify the experiment by comparing the results. Through the steady-state simulation research mode, different permutations and combinations of the two process parameters are simulated to study their effects. Quantitative reference indicators include but are not limited to dependent variables such as the fluid flow velocity, shear rate, temperature distribution and phase transition, and the shear heating process of the injection screw is taken into account in the mold flow analysis to ensure that the die index value is more accurate. It can be seen from the analysis results that the temperature of the barrel changes after the groove depth and groove width are changed, and the effect ratio of the groove depth is lower than that of the groove width in the same degree of size change.

Current Progress in Visible Light-induced Synthesis and Functionalization of N- and S-Heterocycles: A Sustainable Perspective

Heterocycles are of much importance as the majority of the existing drugs contain one or more heterocyclic units in their structures. Among all the heterocycles, nitrogen, and sulphurcontaining ones occupy major space, and they have special properties which make them suitable for the textile, cosmetic, and paint industries other than pharmaceutical. Recently, visible light has emerged as a powerful tool for performing various reactions at ambient temperatures and mild conditions and thus it has been used for the key step in the synthesis of many molecules. In addition, visible light assisted methods are usually cost and time effective. Thus, this review highlighted the recent developments in visible light induced methods for the synthesis of some selected biologically active N- and S- containing heterocycles such as benzothiazoles, indoles and triazoles and their functionalization. The advantages, green aspects and limitations of these methods have also been discussed.

Longitudinal one-dimensional mechanical topological insulator

Abstract We present a study of a longitudinal one-dimensional mechanical topological insulator based on a slinky spring in the Su–Schrieffer–Heeger (SSH) configuration. The system demonstrates key characteristics of topological insulators, including the existence of edge states in the bandgap, exponential decay of amplitude, and a winding number of 1 for topological phases. By manipulating the stiffness of the spring through the placement of masses, we transition between trivial, metallic, and topological phases. Our findings also show that the edge states are robust against perturbations, and we observe a critical phase transition where the coherence length follows a critical exponent of -1, as predicted by theory. This simple mechanical system provides an accessible platform for studying the special properties of topological insulators and opens up new possibilities for exploring topological phenomena in classical systems.

Enhancing Adversarial Robustness through Stable Adversarial Training

Deep neural network models are vulnerable to attacks from adversarial methods, such as gradient attacks. Evening small perturbations can cause significant differences in their predictions. Adversarial training (AT) aims to improve the model’s adversarial robustness against gradient attacks by generating adversarial samples and optimizing the adversarial training objective function of the model. Existing methods mainly focus on improving robust accuracy, balancing natural and robust accuracy and suppressing robust overfitting. They rarely consider the AT problem from the characteristics of deep neural networks themselves, such as the stability properties under certain conditions. From a mathematical perspective, deep neural networks with stable training processes may have a better ability to suppress overfitting, as their training process is smoother and avoids sudden drops in performance. We provide a proof of the existence of Ulam stability for deep neural networks. Ulam stability not only determines the existence of the solution for an operator inequality, but it also provides an error bound between the exact and approximate solutions. The feature subspace of a deep neural network with Ulam stability can be accurately characterized and constrained by a function with special properties and a controlled error boundary constant. This restricted feature subspace leads to a more stable training process. Based on these properties, we propose an adversarial training framework called Ulam stability adversarial training (US-AT). This framework can incorporate different Ulam stability conditions and benchmark AT models, optimize the construction of the optimal feature subspace, and consistently improve the model’s robustness and training stability. US-AT is simple and easy to use, and it can be easily integrated with existing multi-class AT models, such as GradAlign and TRADES. Experimental results show that US-AT methods can consistently improve the robust accuracy and training stability of benchmark models.

Prioritization of Source Data Necessary for the Valuation of Real Estate with Mineral Deposits: The Case of Poland

Real estate valuation with mineral deposits in Poland can be conducted using comparative, income, and cost approaches. When determining the value of such real estate, a property valuer must obtain information from multiple sources. These sources not only help to establish the legal status but also allow for determining the type of geological and mining asset of the deposit, characterizing and assessing the quality of the deposit, describing the deposit's resources, and evaluating the exploitation potential. Analysis of the source documentation also enables the assessment of the environmental state post-exploitation and helps determine the external conditions related to the liquidation of deposits after exploitation. The need to include the above information in the appraisal report requires the property valuer to gather a large amount of source information scattered across private and institutional resources. Therefore, this study aims to identify and prioritize the source data necessary for the valuation process of land properties with mineral deposits in Poland using selected business techniques. As part of achieving the research goal, the method of valuing the subject special property will be recognized, and the source materials will be identified. Their prioritization will be performed using two business techniques: the MoSCoW method and the Action Priority Matrix. In the final stage of the study, utility classes of the source materials for the valuation of the subject property will be developed

Specification and ω-chaos in non-compact systems

In this paper, we demonstrate conditions under which a Lindelöf dynamical system exhibits ω-chaos. In particular, if a system exhibits a generalized version of the specification property and has at least three points with mutually separated orbit closures, then the system exhibits dense ω-chaos.

Theoretical Design of Thorium Nitride MXenes.

Actinides with 5f6d7s valence orbitals feature special physicochemical properties different from those of the other elements. Actinide-based two-dimensional (2D) materials combine the distinctive physics of actinides with the quantum size effect of 2D materials, but relevant studies are scarce. Since Th has a valence electron configuration of 6d27s2 like Ti, and Ti-based MXenes show excellent stability and versatile applications, whether Th can form stable MXenes has become an intriguing question. Herein, we designed Th2N, Th3N2, and Th4N3 MXenes and investigated their physical properties, functionalization, and potential applications using density functional theory. Their stabilities are validated by global minimum search, phonon spectra, ab initio molecular dynamics, enthalpy of formation, and energy above the hull. All the Th-N MXenes exhibit metallic properties and are stabilized by the electrostatic interaction between Th and N ions, as well as the covalent bonding interaction between the Th 6d/5f and N 2p/2s orbitals. The H-, O-, and F-functionalization3N2 MXene improve its stability while preserving its metallicity, and the O-functionalized Th3N2 MXene shows promising catalytic activity for hydrogen evolution. The thorium nitride MXenes enrich the family of actinide-based 2D materials and extend our understanding of the structures and properties induced by actinide elements in low-dimensional materials.

Anthropogenic noise and impact on marine species : Acoustic metamaterials as a reduction solution

Anthropogenic underwater noise generated by offshore maritime activities poses a significant threat to nearby ecosystems due to elevated sound levels. Efforts have to be undertaken on noise reduction solutions, depending both on the offshore activities and on the marine species. In this context, leveraging the recent advances in underwater acoustic metamaterials seems crucial, due to their special properties in terms of scattering and absorption. This endeavor aligns with advancing Marine Renewable Energies while minimizing environmental impact. In this communication, a synthetic review is first proposed to define the various maritime works targeted, as well as their associated sound levels and frequency ranges of emission. In a second part, a cartography is outlined by classifying different marine species according to their hearing type, depth of immersion and auditory threshold. Then, in relation with the two previous analyses, solutions based on metamaterials for deep sea immersions are proposed. In particular, a multi-periodic arrangement of bars is proposed that exhibits several band gaps (i.e. frequency ranges in which propagation is forbidden), in order to limit the transmission of sound waves in a large frequency range. The concept can be easily extended depending on the targeted offshore activities and marine species.

Chebyshev subdivision and reduction methods for solving multivariable systems of equations

We present a new algorithm for finding isolated zeros of a system of real-valued functions in a bounded interval in Rn. It uses the Chebyshev proxy method combined with a mixture of subdivision, reduction methods, and elimination checks that leverage special properties of Chebyshev polynomials. We prove the method has quadratic convergence locally near simple zeros of the system. It also finds all nonsimple zeros, but convergence to those zeros is not guaranteed to be quadratic. We also analyze the arithmetic complexity and the numerical stability of the algorithm and provide numerical evidence in dimensions up to five that the method is both fast and accurate on a wide range of problems. Our tests show that the algorithm outperforms other standard methods on the problem of finding all real zeros in a bounded domain. Our Python implementation of the algorithm is publicly available at https://github.com/tylerjarvis/RootFinding.

Cu-trimesate and mesoporous silica composite as adsorbent showing enhanced CO2/CH4 and CO2/N2 selectivity for biogas and flue gas separation

Due to their diverse structure, high porosity, and tunable functionality, Metal-Organic Frameworks (MOFs) hold great potential as materials for diverse applications, including gas separation. Material science researchers are focusing on creating flexible materials that have special properties. Most of the latest research mainly concentrates on fabricating composite materials of MOFs and other functional materials. These MOF-based composites can mitigate the limitations of pure MOFs and may even perform better than the individual components. Here, we present a systematic study on the effect of solvent in synthesising a composite (Cu-BTC@SBA-15) of Cu-trimesate MOF (aka CuBTC) and ordered mesoporous silica SBA-15, showing considerable improvement in selectivity for CO2 adsorption from the flue gas and biogas. The pristine Cu-BTC, SBA-15 and the composites with different content of Cu-BTC were characterized by PXRD, BET, FT-IR, SEM, TEM and TGA techniques. The pure gas adsorption isotherms were measured for CO2, CH4, and N2 gases. Ideal Adsorbed Solution Theory (IAST) is used for the binary selectivity calculations for gas systems such as CO2/CH4 and CO2/N2 in the context of biogas and flue gas separation. The composite exhibited an increase in CO2/CH4 selectivity by 39 % compared to pure Cu-BTC and 85 % compared to pure SBA-15. For the CO2/N2 system, the composite showed 38 % higher selectivity than Cu-BTC. The work has significance in the design of effective MOF-based composites for CO2 separation. Our work might open up a new route to design multifunctional materials for worldwide applications through an adsorptive and or mixed matrix membrane route.

SPECIAL LEGAL CAPACITY OF LAWYERS: LAWYER, NOTARY AND EXECUTOR

The research object of this paper is the special legal capacity of lawyers, specifically, the special legal capacity for the performance of advocacy activities, regulated by the Law of Advocacy, the special legal capacity for providing notarial services, according to the Law on notaries, and the special legal capacity of the executors, according to the Law on Enforcement. Full legal capacity is the abstract possibility of physical and legal persons to be the provider of rights and obligations. All physical persons have full legal capacity, however, some physical persons, because they fulfill special properties, acquire special legal capacity. The research in this paper has two mail purposes. The first intention is to analyze two assumptions necessary for achieving the special legal skills: 1. professional technical conditions requirements that must be completed by the natural person to operate the professional activities and 2. providing the authorization by the government. The second goal is to show the specifics of the three types of professional activities, notion, acquire, cease and termination. The project will analyze more closely the termination of the special legal capacity because of the loss of one from the two-expectations necessary for its acquisition (obtaining a lawyer's license, terminating the notary or the executor).

The bound states in the continuum of coupled resonance modes and multiple-function applications in grating-cavity structures

The bound states in the continuum (BICs) are desired for high-performance optical devices. The structures composed of gratings and cavities were investigated. Grating waveguide modes (GWMs) are excited by the grating in structures. When the symmetry of the structure is broken, the positive and opposite GWMs couple and generate upper- and lower-coupled modes. Two coupled modes show different properties, such as the Fabry-Pérot (F-P) BIC in lower-coupled mode and the symmetry-protected (SP) BICs in upper-coupled mode. The special properties indicate the two coupled modes are desirable for multifunctional applications. The radiation from the quantum emitter (QE) was enhanced 3030 times through the quasi-BIC of lower-coupled mode. The maximal group delay reached 6.1 ps by the quasi-BIC of the lower-coupled mode. The quasi-BIC of the upper-coupled mode generates high-performance absorption. Two coupled resonance modes are sensitive to polarization, which can be used for optical switching with a maximal amplitude modulation depth of up to 99.8% with an insertion loss of less than 0.008 dB. These results offer hope for developing multifunctional and high-performance devices through coupled resonance modes in the grating-cavity structures.

Optimizing fountain codes for DNA data storage

Fountain codes, originally developed for reliable multicasting in communication networks, are effectively applied in various data transmission and storage systems. Their recent use in DNA data storage systems has unique challenges, since the DNA storage channel deviates from the traditional Gaussian white noise erasure model considered in communication networks and has several restrictions as well as special properties. Thus, optimizing fountain codes to address these challenges promises to improve their overall usability in DNA data storage systems. In this article, we present several methods for optimizing fountain codes for DNA data storage. Apart from generally applicable optimizations for fountain codes, we propose optimization algorithms to create tailored distribution functions of fountain codes, which is novel in the context of DNA data storage. We evaluate the proposed methods in terms of various metrics related to the DNA storage channel. Our evaluation shows that optimizing fountain codes for DNA data storage can significantly enhance the reliability and capacity of DNA data storage systems. The developed methods represent a step forward in harnessing the full potential of fountain codes for DNA-based data storage applications.The new coding schemes and all developed methods are available under a free and open-source software license.

Unlocking the potential of biocompatible chitosan-hyaluronic acid nanogels labeled with fluorochromes: A promising step toward enhanced FRET bioimaging

Chitosan is a natural polysaccharide widely used in medical formulations as nanoparticles due to their special properties. Our work aimed to assess the biocompatibility of chitosan-hyaluronic acid nanogels labeled with fluorochromes for use in biomedical applications, based on the FRET effect. The preparation method included the ionic gelation, grafting rhodamine or fluorescein isothiocyanate molecules onto the chitosan backbone. To assess the potential applications as fluorescence imaging tools of chitosan-fluorophores conjugates in diagnostics and therapies, SVEC4-10 cells (simian virus 40-transformed mouse microvascular endothelial cell line) and RAW264.7 murine macrophages were used within this study. Good biocompatibility was observed after 6 and 24 h of incubation with nanogels, with no increase in cell death or membrane damage for concentrations up to 120 μg/mL. Both types of fluorescent nanogels presented the tendency to agglomerate on the cell membrane's surface, and few cells were internalized, especially at the periphery of cells. Molecular dynamics simulations showed that distances between fluorophores fitted at values close to those calculated based on FRET experiments. These formulations can further incorporate gadolinium for better nanomedicine tools.

Ion solvation modulating via Imidazolidinyl urea additive for stable Zn2+ deposition

The development of energy conversion and storage equipment is a necessary guarantee for social development, and aqueous Zn-ion batteries have become a promising alternative to Li-ion batteries due to its high safety, environmental friendliness, and low cost. However, aqueous Zn-ion batteries suffer from the dendrite growth and parasitic reactions, which hinder the wide application of the batteries. In this paper, imidazolidinyl urea (IDU) is added to aqueous electrolytes because of the special structural properties of IDU. The effects of IDU as an additive on battery stability are elucidated through theoretical modelling, calculations, and experimental validation. Firstly, the effect of concentration on the ion transport properties of the electrolyte was obtained by modelling and calculating the Zn2+ diffusion coefficient and ionic conductivity of electrolytes with different concentrations of IDU added. In addition, the optimal IDU addition concentration was achieved by verification of cycling experiments in Zn symmetric cells. Moreover, it was confirmed using in situ deposition experiments that the addition of IDU could participate in the coordination of Zn2+ into the solvated layer of Zn2+, thereby accelerating the desolvation process of Zn2+, and further improving the uneven deposition of Zn on the negative electrode surface and the growth of dendrites. Finally, it was verified that the IDU addition could enhance the cycle life and stability of the battery, maintaining an efficiency of about 95% and a specific capacity of discharge of 90 mAh·g-1 after more than 1000 cycles in a full cell assembled from Zn flakes and improved iodine electrodes.

Synergistic Effect of Silver Nanoparticles with Antibiotics for Eradication of Pathogenic Biofilms.

The increase in nosocomial multidrug resistance and biofilm-forming bacterial infections led to the search for new alternative antimicrobial strategies other than traditional antibiotics. Silver nanoparticles (AgNP) could be a viable treatment due to their wide range of functions, rapid lethality, and minimal resistance potential. The primary aim of this study is to prepare silver nanoparticles and explore their antibacterial activity against biofilms. AgNPs with specific physicochemical properties such as size, shape, and surface chemistry were prepared using a chemical reduction technique, and then characterized by DLS, SEM, and FTIR. The activity of AgNPs was tested alone and in combination with some antibiotics against MDR Gram-negative and Gram-positive planktonic bacterial cells and their biofilms. Finally, mammalian cell cytotoxicity and hemolytic activity were tested using VERO and human erythrocytes. The findings of this study illustrate the success of the chemical reduction method in preparing AgNPs. Results showed that AgNPs have MIC values against planktonic organisms ranging from 0.0625 to 0.125 mg/mL, with the greatest potency against gram-negative bacteria. It also effectively destroyed biofilm-forming cells, with minimal biofilm eradication concentrations (MBEC) ranging from 0.125 to 0.25 mg/ml. AgNPs also had lower toxicity profiles for the MTT test when compared to hemolysis to erythrocytes. Synergistic effect was found between AgNPs and certain antibiotics, where the MIC was dramatically reduced, down to less than 0.00195 mg/ml in some cases. The present findings encourage the development of alternative therapies with high efficacy and low toxicity.

Application of thin slice technology of loose cuttings sample in early stage of experimental geology

Abstract Thin section of rock is a highly technical work in the laboratory, and its application in logging site and rock identification is helpful to solve geological problems quickly in the process of exploration drilling. The cuttings samples cover a variety of lithologies, including sandstone and volcanic rocks with significant diagenetic differences. Due to the special properties of the cuttings, such as loose, fear of water, moisture absorption, brittleness, large hardness differences, inconsistent particle size, and not easy to penetrate glue, the production process has been challenged. In the temperature and humid environment, the cuttings are very susceptible to delixing, especially in the cuttings with cleavage development, more cracks and poor diagenesis. After the sticking sheet is affected by vibration during rough grinding, it is easy to produce warping edge and warping Angle, which leads to the destruction of the original structure of the mineral. The previous production process cycle is long, the operation is relatively not convenient, especially in the grinding into the international standard 0.03mm thick pieces there are certain difficulties. Therefore, it is very important to improve and optimize the rock wafer technology. This will help improve the efficiency of the production of cuttings and reduce the likelihood of damage to mineral structures, which in turn can be used more effectively in exploration drilling sites and rock identification, providing faster and more accurate support for solving geological problems. The results of this study have important significance for improving the efficiency and convenience of the production process and improving the application prospect of the rock sheet technology.