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There is an increasing need for compact low-cost NMR apparatus that can be used on the laboratory bench and in the field. There are four main usage variants of usage: (a) time-domain apparatus, particularly for physical measurements; (b) frequency-domain apparatus, particularly for chemical analysis, (c) NMR Cryoporometry apparatus for measuring pore-size distributions; and (d) MRI apparatus for imaging. For all of these, variable temperature capability may be vital. We have developed compact low-cost apparatus targeted at these applications. We discuss a hand-held NMR Spectrometer, and three different holdable NMR magnets, with sufficiently large internal bores for the Lab-Tools compact Peltier thermo-electric cooled variable-temperature probes. Currently, the NMR Spectrometer is very suitable for (a) NMR time-domain relaxation and (c) NMR Cryoporometry. With a suitable high-homogeneity magnet, it is also appropriate for simple use (b), spectral analysis, or, with a suitable gradient set, (d) MRI. Together, the NMR Spectrometer, one of the NMR variable-temperature probes, and any of these NMR magnets make excellent NMR Cryoporometers, as demonstrated by this paper and previously published research. Equally, they make versatile general-purpose variable-temperature NMR systems for materials science.

As triboelectric nanogenerator (TENG) technology continue to evolve, its application in harsh environments has increasingly captivated the interest of researchers. However, the current research on heat-resistant triboelectric materials remains predominantly focused on the development of tribo-negative materials, with scant attention given to their equally crucial tribo-positive counterparts. In this study, the tribo-positive polyimide (PI) material with enhanced tribo-positivity is developed by integrating amide groups with electron-donating effects into the molecular chain. Furthermore, the TENG devices based on this series of tribo-positive PI materials have demonstrated an open-circuit voltage (VOC) of 242 V, a short-circuit current (ISC) of 8.13 μA, and a transferred charge (QSC) of 117 nC. Notably, these devices also demonstrate the capability to efficiently generate electricity even under elevated temperature conditions. This work not only proposes a potential molecular design strategy for developing high-performance tribo-positive PI materials applicable in TENGs, but also markedly propels the advancement of robust energy-harvesting devices engineered for operation at elevated temperatures.

The Casimir effect has been exploited in various MEMS (micro-electro-mechanical system) devices, especially to make sensitive force sensors and accelerometers. It has also been used to provide forces for a variety of purposes, for example, for the assembly of considerably small parts. Repulsive forces and torques have been produced using various configurations of media and materials. Just a few electronic devices have been explored that utilize the electrical properties of the Casimir effect. Recently, experimental results were presented that described the operation of an electronic device that employed a Casimir cavity attached to a standard MIM (metal–insulator–metal) structure. The DC (direct current) conductance of the novel MIM device was enhanced by the attached cavity and found to be directly proportional to the capacitance of the attached cavity. The phenomenological model proposed assumed that the cavity reduced the vacuum fluctuations, which resulted in a reduced injection of carriers. The analysis presented here indicates that the optical cavity actually enhances vacuum fluctuations, which would predict a current in the opposite direction from that observed. Further, the vacuum fluctuations near the electrode are shown to be approximately independent of the size of the optical cavity, in disagreement with the experimental data which show a dependence on the size. Thus, the proposed mechanism of operation does not appear correct. A more detailed theoretical analysis of these devices is needed, in particular, one that uses real material parameters and computes the vacuum fluctuations for the entire device. Such an analysis would reveal how these devices operate and might suggest design principles for a new genre of electronic devices that make use of vacuum fluctuations.

This paper presents a two-qubit model derived from an SU(2)-symmetric 4×4 Hamiltonian. The resulting model is physically significant and, due to the SU(2) symmetry, is exactly solvable in both time-independent and time-dependent cases. Using the formal, general form of the related time evolution operator, the time dependence of the entanglement level for certain initial conditions is examined within the Rabi and Landau–Majorana–Stückelberg–Zener scenarios. The potential for applying this approach to higher-dimensional Hamiltonians to develop more complex exactly solvable models of interacting qubits is also highlighted.

The elastic and inelastic scattering of deuterons on 10B nuclei and the 10B(d, t)9B reaction were studied at a deuteron energy of 14.5 MeV. In inelastic scattering, differential cross-sections for transitions to 10B states at excitation energies, Ex, of 0.718 MeV (1+), 2.154 MeV (1+), and 3.59 MeV (2+) were measured. The cross-sections of the (d, t) reaction were measured for the ground (3/2−) and excited states of the 9B nucleus at Ex = 2.361 MeV (5/2−) and 2.79 MeV (5/2+). An analysis of the corresponding angular distributions was carried out using the coupled channel method. As a result of the calculations, the values of the quadrupole deformation parameters (β2 ≈ 0.7 ± 0.1) for various transitions in the 10B nucleus in inelastic scattering were extracted. From the analysis of the (d, t) reaction, the values of spectroscopic amplitudes (SA = 0.67 and SA = 0.94) for transitions to the states of the 9B nucleus were extracted. The results obtained here, taking into account possible measurement errors, are in good agreement with the previously obtained data and the theoretical predictions.

The latest results of Higgs boson searches beyond the Standard Model from the ATLAS and CMS experiments are reviewed. This includes searches for additional neutral, charged, and double charged Higgs-like bosons, searches for dark matter produced in association with a Higgs boson, and searches for new physics in Higgs boson production and decay processes. Interpretations are given within the hMSSM, a special parameterization of the Minimal Supersymmetric extension of the Standard Model, in which the mass of the lightest Higgs boson is set to the value of 125 GeV measured at the LHC.

Two-level quantum systems are building blocks of quantum technologies, where the qubit is the basic unit of quantum information. The ability to design driving fields that produce prespecified evolutions of relevant physical observables is crucial to the development of such technologies. Using vector algebra and recently developed strategies for generating solvable two-level Hamiltonians, we construct the general solution to the inverse problem for a spin in a time-dependent magnetic field and its extension to any two-level system associated with fictitious spin and field. We provide a general expression for the field that drives the dynamics of the system so as to realize prescribed time evolutions of the expectation values of the Pauli operators and the autocorrelation of the Pauli vector. The analysis is applied to two-state charge transfer systems, showing that the charge transfer process can be seen as a motion of the state of the associated fictitious qubit on the Bloch sphere, and that the expectation values of the related Pauli operators describe the interference between the two differently localized electronic states and their population difference. Our formulation is proposed as a basic step towards potential uses of charge transfer in quantum computing and quantum information transfer.

As it turns out, both isotope scaling and density limits are phenomena closely linked to fluid closure. The necessity to include ion viscosity arises for both phenomena. Thus, we have added ion viscosity to our model. The experimental isotope scaling has been successfully recovered in our fluid model through parameter scans. Although ion viscosity typically exerts a small effect, the density limit is manifested by increasing the density by approximately tenfold from the typical experimental density. In our case, this increase originates from the density in the Cyclone base case. Notably, these phenomena would not manifest with a gyro-Landau fluid closure. The isotope scaling is nullified by the addition of a gyro-Landau term, while the density limit results from permitting ion viscosity to become comparable to the gyro-Landau term. The mechanism of zonal flows, demonstrated analytically for the Dimits upshift, yields insights into the isotope scaling observed in experiments. In our approach, ion viscosity is introduced in place of the Landau fluid resonances found in some fluid models. This implies that the mechanism of isotope scaling operates at the level of fluid closure in connection with the generation of zonal flows. The strength of zonal flows in our model has been verified, particularly in connection with the successful simulation of the nonlinear Dimits shift. Consequently, a role is played by our approach in the temperature perturbation part of the Reynolds stress.

In the transient phase of an atmospheric pressure discharge, the avalanche turns into a streamer discharge with time. Hydrodynamic fluid models are frequently used to describe the formation and propagation of streamers, where charge particle transport is dominated by the creation of space charge. The required electron transport data and rate coefficients for the fluid model are parameterized using the local mean energy approximation (LMEA) and the local field approximation (LFA). In atmospheric pressure applications, the excited species produced in the electrical discharge determine the subsequent conversion chemistry. We performed the fluid model simulation of streamers in nitrogen gas at atmospheric pressure using three different parametrizations for transport and electron excitation rate data. We present the spatial and temporal development of several macroscopic properties such as electron density and energy, and the electric field during the transient phase. The species production efficiency, which is important to understand the efficacy of any application of non-thermal plasmas, is also obtained for the three different parametrizations. Our results suggest that at atmospheric pressure, all three schemes predicted essentially the same macroscopic properties. Therefore, a lower-order method such as LFA, which does not require the solution of the energy conservation equation, should be adequate to determine streamer macroscopic properties to inform most plasma-assisted applications of nitrogen-containing gases at atmospheric pressure.

The need for sustainable energy solutions is steering research towards green fuels. One promising approach involves electrocatalytic gas conversion, which requires efficient catalyst surfaces. This study focuses on developing and testing a hydrophobic octadiene (OD) coating for potential use in electrocatalytic gas conversion. The approach aims to combine a plasma-deposited hydrophobic coating with air-trapping micro- and nanotopographies to increase the yield of electrocatalytic reactions. Plasma polymerisation was used to deposit OD films, chosen for their fluorine-free non-polar properties, onto titanium substrates. We assessed the stability and charge permeability of these hydrophobic coatings under electrochemical conditions relevant to electrocatalysis. Our findings indicate that plasma-deposited OD films, combined with micro-texturing, could improve the availability of reactant gases at the catalyst surface while limiting water access. In the presence of nanotextures, however, the OD-coated catalyst did not retain its hydrophobicity. This approach holds promise to inform the future development of catalyst materials for the electrocatalytic conversion of dinitrogen (N2) and carbon dioxide (CO2) into green fuels.

The occurrence of emerging micropollutants of pharmaceutically active compounds (PhACs) in the environment poses a public health concern. Due to PhAC persistence and toxicity even at low concentrations, advanced oxidation processes (AOPs) have gained interest as effective treatment methods. In this context, the present study focuses on the application of a dielectric barrier discharge (DBD)-based plasma jet to Diclofenac (DCF) and Sulfamethoxazole (SMX) degradation in aqueous media. Plasma is sustained by continuous-wave sinusoidal high-voltage of audio frequencies, and negligible total harmonic distortion, in a helium–air mixture. The target pharmaceuticals are chosen based on anticipation of their occurrence due to rehabilitation center (DCF) and hospital (SMX) effluents in sewage systems. The degradation rates are determined by Liquid Chromatography Triple-Quadrupole Mass Spectroscopy (LC-MS/MS). Removal efficiency close to 100%, after 20 min of plasma treatment in the case of DCF at an initial concentration of 50 ppb, is achieved. The post-treatment action of the plasma-induced reactants on PhAC degradation over a day-scale period is studied. The results provide an insight into the dynamic degradation (kinetics) of both DCF and SMX, and they overall highlight the potentiality of the process under consideration for sewage remediation.

Methylene blue (C16H18ClN3) dye can be decomposed using non-thermal plasma. However, there is a problem in that the maintenance of electrodes and dielectrics is necessary due to the durability and heat generation problems due to the high temperatures. Therefore, in this study, a comparative experiment was performed between the flat DBD plasma module and the diffuser DBD module under the same conditions. For methylene blue decomposition, the characteristic changes in the air flow rate, ozone production rate, energy consumption rate, and decomposition rate were compared. In the experiment, 7 L water was placed in a 15 L reactor, and measurements were performed for approximately 1 h. We performed the same process by setting the initial methylene blue concentration to 143 mg/L. According to the results, the flat DBD module achieved a decomposition rate of 100% in 40 min, an energy yield of 46.7 g/kWh, and an ozone generation amount of 6.5 g/h. The diffuser DBD module achieved a decomposition rate of 90%, an energy production of 24.6 g/kWh, and an ozone generation of 1.97 g/h in 60 min.

This paper examines no-hidden-variables theorems in quantum mechanics from the point of view of statistical mechanics. It presents a general analysis of the measurement process in the Boltzmannian framework that leads to a characterization of (in)compatible measurements and reproduces several features of quantum probabilities often described as “non-classical”. The analysis is applied to versions of the Kochen–Specker and Bell theorems to shed more light on their implications. It is shown how, once the measurement device and the active role of the measurement process are taken into account, contextuality appears as a natural feature of random variables. This corroborates Bell’s criticism that no-go results of the Kochen–Specker type are based on gratuitous assumptions. In contrast, Bell-type theorems are much more profound, but should be understood as nonlocality theorems rather than no-hidden-variables theorems. Finally, the paper addresses misunderstandings and misleading terminology that have confused the debate about hidden variables in quantum mechanics.

Recent developments in the quantization of general relativity theory provide a new perspective on matter and even the whole universe. Already, in 1922, Eddington suggested that a future quantum gravity theory had to be linked to Planck length. This is today the main view among many working with quantum gravity. Recently, it has been demonstrated how Planck length, the Planck time, can be extracted from gravity observations with no knowledge of G, ℏ, or even c. Rooted in this, both general relativity theory and multiple other gravity theories can be quantized and linked to the Planck scale. A revelation from this is that matter seems to be ticking at the reduced Compton frequency, where each tick can be seen as one bit, and one bit corresponds to a Planck mass event. This new speculative way of looking at gravity can also potentially tell us considerably about what quantum gravity computers are and what they potentially can do. We will conjecture that that all quantum gravity and quantum gravity computers are directly linked to the Planck scale and the Compton frequency in matter, something we will discuss in this paper. Quantum gravity computers, we will see, in many ways, are nature’s own designed computers with enormous capacity to 3D “print” real time. So, somewhat speculatively, we suggest we live inside a gigantic quantum gravity computer known as the Hubble sphere, and we even are quantum gravity computers. The observable universe is based on this model, basically a quantum gravity computer that calculates approximately 10104 bits per second (bps).

In this article, I start with a general presentation of the ideas behind sigma models and higher gauge theories and introduce the possibility of a higher entanglement structure. Using a higher categorial interpretation of entanglement involving gauge theories and σ-models instead of qubits, one recovers T-duality as a form of ancilla aided entanglement generation. This opens the way towards new dualities in gauge theories and σ-models produced by means of analogies with quantum circuits of various types.

The optical characteristics and electrical behavior of zinc oxide nanorods (ZnO-NRs) and silver nanoparticles (Ag-NPs) were investigated using advanced scanning probe microscopy techniques. The study revealed that the ZnO nanorods had a length of about 350 nm, while the Ag nanoparticles were spherical with heights ranging from 5 to 14 nm. Measurements with Kelvin probe force microscopy (KPFM) showed that the work functions of ZnO nanorods were approximately 4.55 eV, higher than that of bulk ZnO, and the work function of Ag nanoparticles ranged from 4.54 to 4.56 eV. The electrical characterization of ZnO nanorods, silver nanoparticles, and their hybrid was also conducted using conductive atomic force microscopy (C-AFM) to determine the local current-voltage (I-V) characteristics, which revealed a characteristic similar to that of a Schottky diode. The current-voltage characteristic curves of ZnO nanorods and Ag nanoparticles both showed an increase in current at around 1 V, and the hybrid ZnONRs/AgNP exhibited an increase in turn-on voltage at around 2.5 volts. This suggested that the presence of Ag nanoparticles enhanced the electrical properties of ZnO nanorods, improving the charge carrier mobility and conduction mechanisms through a Schottky junction. The investigation also explored the optical properties of ZnO-NRs, AgNPs, and their hybrid, revealing absorption bands at 3.11 eV and 3.18 eV for ZnO-NRs and AgNPs, respectively. The hybrid material showed absorption at 3.13 eV, indicating enhanced absorption, and the presence of AgNP affected the optical properties of ZnO-NR, resulting in increased photoluminescence intensity and slightly changes in peak positions.

Atmospheric pressure microplasma is a simple, cost-effective, efficient, and eco-friendly procedure, which is superior to the traditional nanomaterials synthesis techniques. It generates high yields and allows for a controlled growth rate and morphology of nanomaterials. The silver (Ag) nanomaterials, with their unique physical and chemical properties, exhibit outstanding antibacterial and antifungal properties. Similarly, zinc oxide (ZnO) nanomaterials, known for their low toxicity and relatively lower cost, find wide applications in wound repair, bone healing, and antibacterial and anticancer applications. The use of core–shell nanomaterials in certain situations where some nanoparticles can cause serious harm to host tissues or organs is a testament to their potential. A benign material is coated over the core to reduce toxicity in these cases. This review compares the numerous configurations of microplasma systems used for synthesizing nanomaterials and their use in producing Ag, ZnO, and their core–shell (Ag-ZnO) nanomaterials for biomedical applications. The summary also includes the effect of control parameters, including cathode diameter, gas flow rate, precursor concentration, voltage, and current, on the nanomaterial’s characteristics and applications. In addition, it provides a research gap in the synthesis of Ag, ZnO, and core–shell nanomaterials by this technique, as well as the development and limitations of this technique and the use of these nanoparticles for biomedical applications.

High density portable energy storage is desirable owing to the energy requirements of portable electronics and electric vehicles. The Li-ion battery’s high energy density could be even further improved through the utilization of alternative materials (instead of carbon) for the anode, such as Sn or Si. Nonetheless, the large volume expansion upon lithiation, up to ~300% for Li22Si5, causes pulverization and rapid capacity degradation during cycling. Sn also forms a Li22Sn5 compound with the equivalent stoichiometric Li capacity but with enhanced ductility. Nano-sized Si and Sn have demonstrated distinctive nanoscale properties, facilitating the retention of higher capacities, particularly when coated with carbon, which improves mechanical stability. To date, the methods of synthesizing coated Si, Sn, or Si-Sn alloyed nanoparticles are complicated, costly, and not readily scalable to meet the demands of cost-effective manufacturing. Spark plasma erosion in a hydrocarbon dielectric has been explored as a one-step process to produce Sn-Si alloy nanoparticles coated with a thin carbon film, offering a scalable and cost-effective processing route. The resulting Sn-Si particles exhibited a bi-modal size distribution at ~5 nm and ~500 nm and were carbon-coated, as intended, from the hydrocarbon dielectric breakdown. The spark-eroded nanoparticles were thoroughly characterized using TEM/EDS, XPS, AES, SSNMR, and TGA, and their improved electrochemical performance was assessed through half-cell experiments.

The surfaces of ceramic products are replete with numerous defects, such as those that appear during the diamond grinding of sintered SiAlON ceramics. The defective surface layer is the reason for the low effectiveness of TiZrN coatings under abrasive and fretting wear. An obvious solution is the removal of an up to 4-µm-thick surface layer containing the defects. It was proposed in the present study to etch the layer with fast argon atoms. At the atom energy of 5 keV and a 0.5 mA/cm2 current density, the ions were converted into fast atoms and the sputtering rate for the SiAlON samples reached 20 μm/h. No defects were observed in the microstructures of coatings deposited after beam treatment for half an hour. The treatment reduced the volumetric abrasive wear by five times. The fretting wear was reduced by three to four times.

Hypromellose (HM) is a cellulose-derived polymer of pharmaceutical grade that forms easily from thin films and coatings. As few studies concern HM-formulated systems, this study focuses on the formulation of HM films by incorporating a fatty acid additive, making it possible to control surface properties such as wetting and slip behavior for pharmaceutical or medical applications. The results show that the addition of a very small amount (from 0.1 to 1% w/w) of fatty acid additive reduces HM film affinity for water and water vapor transmission rate, while film appearance and gloss are rather preserved. Surface properties were probed using wettability measurements, Tapping Mode AFM, ATR-FTIR spectrometry, and friction measurements. Tapping Mode AFM images show that the surface roughness reduces by up to 65%. Wettability results show that the surface energy decreases from 43 to 31 mJ.m−2, whereas surface FTIR spectrometry measurements demonstrate that fatty acid molecules migrate on the surface of the formulated films, the driving force being the microphase separation between the polar HM macromolecules and the hydrophobic additive, leading to the formation of a weak boundary layer with poor cohesion. As a consequence, the surface coefficient of friction significantly reduces from 0.38 to 0.08, and fatty acid molecules thus act as a lubricant, improving the sliding properties of HM-based coatings.

Bismuth oxide (Bi2O3) and Bi2O3–supported Kaolin were synthesized using household microwave–assisted methods (350 W, 5 min), with catalyst characteristics analyzed. XRD patterns confirmed the monoclinic structure of Bi2O3. Incorporating 20%w/w Kaolin increased the specific surface area of Bi2O3 from 6.2879 to 16.1345 m2/g, observed in FESEM images showing a hierarchical flower-like morphology resembling French fries alongside Kaolin plates. XRF analysis identified elements in Kaolin contributing to self–doping in band structure of Bi2O3, reducing its band gap and PL intensity. Kaolin/Bi2O3 composites demonstrated enhanced photocatalytic degradation of tetracycline (TC) under visible light, attributed to Bi2O3-generated radicals and increased surface area. The composite photocatalyst can be recycled up to three times. This research not only enhances the photocatalytic activity of Bi2O3 but also increases the value of a local waste material, Kaolin clay. Such enhancements could potentially extend to other metal oxides and abundant waste materials within the country.

The extensive global use of rubber results in significant microplastic pollution from the release of tire wear particles and microplastic leachate, impacting the environment, human health, and ecosystems. Waste tires are normally recycled and used for the production of new products, such as rubber tiles. The presented study aims to show the possibility of further decrease in the negative environmental impact of materials based on recycled rubber. This paper presents the modification of rubber tiles with a titanium dioxide (TiO2) coating, focusing on surface integrity, rubber particle wear release, and the consequent environmental impact of leachate release. Both reference and modified rubber tiles were subjected to artificial accelerated aging in a solar simulator for 4, 6, and 8 weeks, followed by an abrasion test. The carbonyl index was calculated from FTIR characterization after each time frame to indicate the degradation of organic compounds and chemical changes caused by UV exposure. A 24 h leaching test with a liquid-to-sample ratio of 1:20 was performed on both rubber tile samples prior to and after 8 weeks of aging along with the aged wear particles for the purpose of the non-target screening of released organic leachate by LC/MS QTOF. The results of carbonyl indices showed that the TiO2 coating contributes to the stabilization of polymer degradation and, to a certain extent, reduces the leaching of organic compounds, such as phthalates. However, the increased wear and release of rubber particles and the subsequent degradation of organic leachates require further in-depth research.

This paper investigates the enhancement of the microstructure and properties of Ag-10La0.7Sr0.3CoO3 composites, prepared by powder metallurgy, through the application of high-current pulsed electron beam (HCPEB) irradiation. The X-ray diffraction results showed that the irradiated samples exhibited selective orientations on the surface of their (200) and (311) crystal planes. Microstructural observations revealed a dense remelted layer on the samples’ surface after HCPEB irradiation. The surface hardness of the samples increased after 15 treatments, showing an improvement of 36.76%. This is primarily attributed to fine-grain strengthening, surface remelting, and recrystallization. Further, the electrical conductivity of the samples treated 15 times increased by 74.8% compared to that of the original samples. Electrochemical test results showed that the samples treated 15 times showed the lowest corrosion current density in a 3.5 wt.% NaCl solution. This improved corrosion resistance is attributable to the refinement of the surface’s microstructure and the introduction of residual compressive stress. This study demonstrates the significant impact of HCPEB irradiation on the regulation of the properties of Ag-10La0.7Sr0.3CoO3 composites.

Polymer-based molecular tweezers have emerged as a prominent research area due to their enhanced ability to form host–guest complexes, driven by advancements in their design and synthesis. The impact of the spacer structure on the tweezers is predominant. They can be rigid, flexible, and stimuli-responsive. Herein, a new generation of molecular tweezers is introduced as polymer-based molecular tweezers. The integration of molecular tweezers onto biopolymers has significantly expanded their potential applications, making them promising candidates, especially in drug delivery, owing to their biocompatibility, adaptive structural features, and versatile interaction capabilities. The unique structure of polymer-based molecular tweezers, particularly when integrated with biopolymers, creates a unique nano-environment that enhances their interaction with guest molecules. This minireview focuses on the synthesis and applications of polymer-based molecular tweezers and examines how the incorporation of various spacers affects their binding affinity and specificity. These features highlight the advancement of these polymer-based systems, emphasizing their potential applications, particularly in drug delivery, water treatment technology, and future research opportunities.

In this study, we introduce progress in intelligent control for reducing structural vibrations. The field of intelligent control for dampening structural vibrations is evolving rapidly, driven by advancements in materials science, AI, and actuator technology. These innovations have led to more efficient, reliable, and adaptable vibration-control systems with applications ranging from civil engineering to aerospace. The use of smart materials has opened new avenues for vibration control of piezoelectric materials. When mechanical stress is applied to these materials, an electric charge response is formed, allowing for precise control over the vibrations. Improved computational models and simulations play crucial roles in the design and testing of vibration-control systems. Finite element analysis helps in accurately predicting the behavior of structures under various loads, thereby aiding in the design of effective vibration-control systems. In our work, we use intelligent control theory to dampen structural vibrations in engineering structures.

This paper presents a decoupled modal reduction method for the steady-state vibration analysis of vibro-acoustic systems characterized by non-classical damping. The proposed approach initially reduces the order of the coupled governing equations of the vibro-acoustic system through the utilization of non-coupled modes, subsequently employing the complex mode superposition technique to address non-classical damping effects. By leveraging non-coupled modes, this method circumvents the need to solve for coupled modes as required in traditional modal reduction techniques, thereby diminishing both computational complexity and cost. Furthermore, the complex mode superposition method facilitates the decoupling of coupled governing equations with non-classical damping, enhancing computational efficiency. Numerical examples validate both the accuracy and effectiveness of this methodology. Given that modal decomposition is independent of frequency, an analysis of computational efficiency across various stages further substantiates that this method offers significant advantages in terms of efficiency for computational challenges encountered over a broad frequency range.

Zinc oxide (ZnO) is one of the most versatile semiconductor materials with many potential applications. Understanding the interactions between the surface chemistry of ZnO along with its physico-chemical properties are essential for the development of ZnO as a robust photocatalyst for the removal of aqueous pollutants. We report on the fabrication of nanoparticle-like porous ZnO films and the correlation between the fabrication process parameters, particle size, surface oxygen vacancies (SOV), photoluminescence and photocatalytic performance. The synthesis route is unique, as highly porous zinc layers with nanoscale grains were first grown via magnetron sputtering, a vacuum-based technique, and subsequently annealed at temperatures of 400 °C, 600 °C and 800 °C in oxygen flow to oxidise them to zinc oxide (ZnO) while maintaining their porosity. Our results show that as the annealing temperature increases, nanoparticle agglomeration increases, and thus there is a decrease in the active sites for the photocatalytic reaction. However, for selected samples the annealing leads to an increase of the photocatalytic efficiency, which we explain based on the analysis of defects in the material, based on photoluminescence (PL). PL analysis showed that in the material the transition between the conduction band and the oxygen vacancy is responsible for the green emission centered at 525 nm, but the photocatalytic activity correlated best with surface states—related emission.

Article presents a comparison of surface structure study methods, such as atomic force microscopy, scanning and transition electron microscopy in terms of metallic materials 3D-printed using the laser powder bed fusion technique. The main features, advantages, disadvantages of atomic force microscopy as a research method for the LPBF synthesized samples are discussed in the context of hard magnetic material, specifically Nd-Fe-B. The ability to provide qualitative grain structure analysis with the high-resolution images of atomic force microscopy is comprehensively studied. For confirmation good applicability of the above-mentioned method for LPBF sample analysis images of a magnetic domain structure obtained via atomic force microscopy are presented. Thus, the applicability of atomic force microscopy to the quality microstructural investigation of metallic materials obtained by LPBF is demonstrated.

To investigate how hydrodynamic cavitation (HC) affects the adsorption of sodium oleate (NaOl) on diaspore and kaolinite surfaces, a comparative study on NaOl adsorption was conducted under different conditions. The flotation and separation of the minerals were also examined with and without HC pretreatment of NaOl. The results show that short-term HC pretreatment of NaOl solutions did not induce a measurable change in the chemical structure of NaOl, but produced micro-nanobubbles (MNBs) and resulted in decreases in the surface tension and viscosity of liquids. When MNBs interacted with minerals, their anchor on solids could affect the contact angles, zeta potentials, and surface NaOl adsorption toward minerals. At low NaOl concentrations, the presence of MNBs reduced the NaOl adsorption capacity and particles’ zeta potential while increasing the minerals’ contact angle. At higher NaOl concentrations, the presence of MNBs promoted NaOl adsorption, further increased the minerals’ contact angle, and further decreases the particles’ zeta potential. Additionally, the flotation and separation of minerals can be enhanced at low NaOl concentrations, largely due to the enhanced bubble mineralization through the selective surface-anchoring of MNBs on diaspore. However, the separation efficiency might deteriorate at high NaOl concentrations, though the presence of MNBs amplified the divergences in minerals’ surface wettability and zeta potentials.

In the present study, XRD, SEM/EDS, Raman, EMR/EPR spectroscopy, and vibrating sample magnetometry (VSM) were used to analyze the reduction of hematite by the carbonization products of waste activated sludge (WAS) at 500–1000 °C. The reduction process includes the following steps: α-Fe2O3 → Fe2O3 + Fe3O4 (Ttr~500 °C) → Fe3O4 (Ttr~600–700 °C) → FeO → Feamorph. (Ttr~1000 °C). The prevalence of certain phase compositions at different hematite reduction temperatures makes it possible to predict the areas viable for the application of reduced oxides: adsorbents (after Ttr~500 °C) → soft ferromagnetic materials (after Ttr~600–700 °C) → electrically engineered amorphous iron (after Ttr~1000 °C).

This study presents the design and simulation of an RF MEMS variable capacitor with a high tuning ratio and high linearity factor of capacitance–voltage response. An electrostatic torsion actuator with planar and non-planar structures is presented to obtain the high tuning ratio by avoiding the occurrence of pull-in point. In the proposed design, the capacitor plate is connected to the electrostatic actuators by using the s-shaped beam. The proposed design shows a 138% tuning ratio with the planar structure of the actuator and 167% tuning ratio by implementing the non-planar structure. A linearity factor of 99% is attained by adjusting the rates at which the capacitor plate rises as the actuation voltage increases and the rate at which the capacitance decreases as the plate rises. Parametric optimization of the design is performed by utilizing the finite element method (FEM) analysis and high-frequency structural simulator (HFSS) analysis to obtain an optimized high-tuning ratio RF MEMS varactor at low actuation voltage. S-parameters of the design are presented on HFSS, with a 50 ohm coplanar waveguide (CPW) serving as the transmission line. The proposed RF MEMS varactor can be utilized in tunable RF devices.

Recent advancements in 3D-bioprinting technology have sparked a growing interest in its application for brain repair, encompassing tissue regeneration, drug delivery, and disease modeling. This literature review examines studies conducted over the past five years to assess the current state of research in this field. Common bioprinting methods and key parameters influencing their selection are explored, alongside an analysis of the diverse types of bioink utilized and their associated parameters. The extrusion-based 3D-bioprinting method emerged as the most widely studied and popular topic, followed by inkjet-based and laser-based bioprinting and stereolithography. Regarding bioinks, fibrin-based and collagen-based bioinks are predominantly utilized. Furthermore, this review elucidates how 3D bioprinting holds promise for neural tissue repair, regeneration, and drug screening, detailing the steps involved and various approaches employed. Neurovascular 3D printing and bioscaffold 3D printing stand out as the top two preferred methods for brain repair. The recent studies’ shortcomings and potential solutions to address them are also examined and discussed. Overall, by synthesizing recent findings, this review provides valuable insights into the potential of 3D bioprinting for advancing brain repairment strategies.

The rise of the Internet of things has catalyzed extensive research in the realm of flexible wearable sensors. In comparison with conventional sensor power supply methods that are reliant on external sources, self-powered sensors offer notable advantages in wearable comfort, device structure, and functional expansion. The energy-harvesting modes dominated by piezoelectric nanogenerators (PENGs), triboelectric nanogenerators (TENGs), and pyroelectric nanogenerators (PyENGs) create more possibilities for flexible self-powered sensors. This paper meticulously examines the progress in flexible self-powered devices harnessing TENG, PENG, and PyENG technologies and highlights the evolution of these sensors concerning the material selection, pioneering manufacturing techniques, and device architecture. It also focuses on the research progress of sensors with composite power generation modes. By amalgamating pivotal discoveries and emerging trends, this review not only furnishes a comprehensive portrayal of the present landscape but also accentuates avenues for future research and the application of flexible self-powered sensor technology.

In the realm of intelligent sports, the integration of triboelectric nanogenerators (TENGs) marks a transformative approach toward energy sustainability and more advanced athletic monitoring. By leveraging the principle of triboelectricity, TENGs ingeniously convert mechanical energy from athletes’ movements into electrical energy, which offers a green and efficient power solution for wearable technology. This paper presents an innovative study on the application of TENG technology in sports science, with the results illustrating the potential utility of TENGs in revolutionizing the way we monitor, analyze, and enhance athletic performance. Through the development of self-powered wearables and equipment, TENGs facilitate real-time data collection on physiological and biomechanical parameters, ultimately enabling personalized training adjustments and injury prevention strategies. Our findings underscore the dual benefit of TENGs in promoting environmental sustainability by reducing the overall reliance on traditional energy sources and growing the capabilities of intelligent sports systems. This research contributes to the burgeoning field of nano-energy sports applications while setting the stage for future explorations into the optimization of TENG integration in athletic performance enhancement. Finally, the paper concludes by discussing remaining challenges in this area and opportunities for further research.

In this paper, we review some recent findings related to the Casimir effect. Initially, the thermal corrections to the vacuum Casimir energy density are calculated, for a quantum scalar field, whose modes propagate in the (3+1)-dimensional Euclidean spacetime, subject to a nontrivial compact boundary condition. Next, we analyze the Casimir effect induced by two parallel plates placed in a weak gravitational field background. Finally, we review the three-dimensional wormhole solutions sourced by the Casimir density and pressures associated with the quantum vacuum fluctuations of the Yang-Mills field.

Ferroelectric charged domain walls offer a revolutionary path for next-generation ferroelectric devices due to their exceptional conductivity within an otherwise insulating matrix. However, quantitative understanding of this “giant conductivity” has remained elusive due to the lack of robust models describing carrier behavior within CDWs. The current paper bridges this critical knowledge gap by employing a first-principles approach that incorporates Boltzmann transport theory and the relaxation time approximation. This strategy enables the calculation of carrier concentration, mobility, and conductivity for both head-to-head and tail-to-tail domain wall configurations within a stabilized periodic structure. The comprehensive transport analysis given here reveals that the accumulation of charge carriers, particularly their concentration, is the dominant factor governing domain wall conductance. Interestingly, observed conductance differences between head-to-head and tail-to-tail walls primarily arise from variations in carrier mobility. Additionally, this study demonstrates a significantly reduced domain wall width compared to previous reports. This miniaturization is attributed to the presence of compressive strain, which lowers the energy barrier for electron–hole pair generation. Furthermore, the findings here suggest that reducing the band gap presents a viable strategy for stabilizing charged domain walls. These results pave the way for the optimization and development of domain wall devices across a spectrum of ferroelectric materials.

In the present introductory to the Special Issue “75 Years of the Casimir Effect: Advances and Prospects”, we summarize the state of the art in this field of physics, briefly describe the topics of the contributing papers, formulate several unresolved problems, and outline possible pathways towards their resolution. Special attention is given to experiments on measuring the Casimir force, to the known problem of the dissipation of conduction electrons when one compares experiment with theory, and to the Casimir effect in novel materials and non-traditional situations. We conclude that in the future, this multidisciplinary quantum effect will continue to play a crucial role in both fundamental physics and its applications.

We review the formalism of center-of-mass tomograms, which allows us to describe quantum states in terms of probability distribution functions. We introduce the concept of separable and entangled probability distributions for center-of-mass tomography. We obtain the time evolution of center-of-mass tomograms of entangled states of the inverted oscillator.

In the context of plasma–liquid interactions, the phase of discharge ignition is of great importance as it may influence the properties of the produced plasma. Herein, we investigated the influence of voltage rising time (τrise) on discharge ignition in air as well as on discharge propagation on the surface of water. Experimentally, τrise was adjusted to 0.1, 0.4, 0.6, and 0.8 kV/ns using a nanosecond high-voltage pulser, and discharges were characterized using voltage/current probes and an ICCD camera. Faster ignition, higher breakdown voltage, and greater discharge current (peak value) were observed at higher τrise. ICCD images revealed that higher τrise also promoted the formation of more filaments, with increased radial propagation over the water surface. To further understand these discharges, a previously developed 2D fluid model was used to simulate discharge ignition and propagation under various τrise conditions. The simulation provided the spatiotemporal evolution of the E-field, electron density, and surface charge density. The trend of the simulated position of the ionization front is similar to that observed experimentally. Furthermore, rapid vertical propagation (τrise increased, the velocity of discharge propagation towards the liquid increased. Higher τrise values also led to more charges in the ionization front propagating at the water surface. The discharge ceased to propagate when the charge number in the ionization front reached 0.5 × 108 charges, irrespective of the τrise value.

Per-and Polyfluoroalkyl substances (PFASs) are recalcitrant organofluorine contaminants, which demand urgent attention due to their bioaccumulation potential and associated health risks. While numerous current treatments technologies, including certain plasma-based treatments, can degrade PFASs, their complete destruction or mineralization is seldom achieved. Extensive aqueous PFAS mineralization capability coupled with industrial-level scaling potential makes gliding arc plasma (GAP) discharges an interesting and promising technology in PFAS mitigation. In this study, the effects of GAP discharge’s thermal and reactive properties on aqueous perfluorooctanesulfonic acid (PFOS) mineralization were investigated. Treatments were conducted with air and nitrogen GAP discharges at different plasma gas temperatures to investigate the effects of plasma thermal environment on PFOS mineralization; the results show that treatments with increased plasma gas temperatures lead to increased PFOS mineralization, and discharges in air were able to mineralize PFOS at relatively lower plasma gas temperatures compared to discharges in nitrogen. Studies were conducted to identify if GAP-based PFOS mineralization is a pure thermal process or if plasma reactive chemistry also affects PFOS mineralization. This was done by comparing the effects of thermal environments with and without plasma species (air discharge and air heated to plasma gas temperatures) on PFOS mineralization; the results show that while GAP discharge was able to mineralize PFOS, equivalent temperature air without plasma did not lead to PFOS mineralization. Finally, mineralization during treatments with GAP discharges in argon and air at similar gas temperatures were compared to investigate the role of plasma species in PFOS mineralization. The results demonstrate that treatments with argon (monoatomic gas with higher ionization) lead to increased PFOS mineralization compared to treatments with air (molecular gas with lower ionization), showing the participation of reactive species in PFOS mineralization.

We investigate the effects of the magnetostatic (B) field topology on the plasma behavior in a 2D collisionless simulation setup that represents an axial–azimuthal cross-section of a Hall thruster. The influence of the B-field topology is assessed in terms of two principal design properties of the field in a typical Hall thruster, i.e., the field’s peak intensity along the axial direction, and the field’s axial distribution. The effects of the field’s intensity are investigated for three propellants—xenon, krypton, and argon. Whereas, the effects of the axial profile of the magnetic field are studied only for the xenon propellant as an example. We primarily aim to understand how the changes in the B-field topology affect the spectra of the resolved instabilities as well as the electrons’ transport characteristics and the contributions of various momentum terms to transport. The numerical observations on the instabilities’ characteristics are compared against the relevant existing theories to determine the extent to which the simulated and the theoretically predicted characteristics are consistent across the studied parameter space. It was, most notably, found that modes related to ion acoustic instability are dominantly present across the simulation cases. The ion transit time instability additionally develops at the highest B-field intensities as a long-wavelength structure. The main influence of the axial profile of the B field on the plasma discharge was observed to be in terms of the electrons’ transport characteristics. Where possible, the insights from the simulations are discussed with respect to the relevant experimental observations available in the literature.

The radiative heat transfer in arc plasma models is considered from the point of view of its description in terms of a net emission coefficient, the method of spherical harmonics in its lowest order, and the discrete ordinate method. Net emission coefficients are computed, applying approximate analytical and numerical approaches and a multi-band representation of the spectral absorption coefficient with three kinds of its averaging and two datasets. Self-consistent access to the radiative heat transfer is applied to a two-dimensional axisymmetric model of a free-burning arc in argon at atmospheric pressure. The results obtained from the models employing the net emission coefficient, the method of spherical harmonics, and the discrete ordinate method are compared.

The results from a wide-ranging parametric investigation into the behavior of the collisionless partially magnetized plasma discharge of three propellants—xenon, krypton, and argon—are reported in this two-part article. These studies are performed using high-fidelity reduced-order particle-in-cell (PIC) simulations in a 2D configuration that represents an axial–azimuthal cross-section of a Hall thruster. In this part I paper, we discuss the effects of discharge voltage and current density (mass flow rate). Our parametric studies assess the spectra of the resolved instabilities under various plasma conditions. We evaluate the ability of the relevant theories from the literature to explain the variations in the instabilities’ characteristics across the studied plasma parameter space and for various propellants. Moreover, we investigate the changes in the electrons’ cross-magnetic-field transport, as well as the significance of the contribution of different momentum terms to this phenomenon across the analyzed cases. In terms of salient observations, the ion acoustic instability (IAI)-related modes are found to be dominant across the simulation cases, with the ion transit time instability also seen to develop at low current density values. Across the explored parameter space, the instabilities have the main contributions to the electrons’ transport within the plume region. The peak of the electric momentum force term, representing the effect of the instabilities, overall shifts toward the plume as either the current density or the discharge voltage increases. The numerical findings are compared against relevant experimental observations reported in the literature.

Quantum Key Distribution (QKD) offers a revolutionary approach to secure communication, leveraging the principles of quantum mechanics to generate and distribute cryptographic keys that are immune to eavesdropping. As QKD systems become more widely adopted, the need for robust monitoring and management solutions has become increasingly crucial. The Cerberis3 QKD system from ID Quantique addresses this challenge by providing a comprehensive monitoring and visualization platform. The system’s advanced features, including central configuration, SNMP integration, and the graphical visualization of key performance metrics, enable network administrators to ensure their QKD infrastructure’s reliable and secure operation. Monitoring critical parameters such as Quantum Bit Error Rate (QBER), secret key rate, and link visibility is essential for maintaining the integrity of the quantum channel and optimizing the system’s performance. The Cerberis3 system’s ability to interface with encryption vendors and support complex network topologies further enhances its versatility and integration capabilities. By addressing the unique challenges of quantum monitoring, the Cerberis3 system empowers organizations to leverage the power of QKD technology, ensuring the security of their data in the face of emerging quantum computing threats. This article explores the Cerberus3 system’s features and its role in overcoming the monitoring challenges inherent to QKD deployments.

Qubit systems based on trapped ultracold ions win one of the leading positions in the quantum computing field, demonstrating quantum algorithms with the highest complexity to date. Surface Paul traps for ion confinement open the opportunity to scale quantum processors to hundreds of qubits and enable high-connectivity manipulations on ions. To fabricate such a system with certain characteristics, the special design of a surface electrode structure is required. The depth of the trapping potential, the stability parameter, the secular frequency and the distance between an ion and the trap surface should be optimized for better performance. Here, we present the optimized design of a relatively simple surface trap that allows several important high-fidelity primitives: tight ion confinement, laser cooling, and wide optical access. The suggested trap design also allows us to perform an important basic operation, namely, splitting an ion chain into two parts.

We present a statistical simulation replicating the correlation observed in EPR coincidence experiments without needing non-local connectivity. We define spin coherence as a spin attribute that complements polarization by being anti-symmetric and generating helicity. Point particle spin becomes structured with two orthogonal magnetic moments, each with a spin of 12—these moments couple in free flight to create a spin-1 boson. Depending on its orientation in the field, when it encounters a filter, it either decouples into two independent fermion spins of 12, or it remains a boson and precedes without decoupling. The only variable in this study is the angle that orients a spin on the Bloch sphere, first identified in the 1920s. There are no hidden variables. The new features introduced in this work result from changing the spin symmetry from SU(2) to the quaternion group, Q8, which complexifies the Dirac field. The transition from a free-flight boson to a measured fermion causes the observed violation of Bell’s Inequalities and resolves the EPR paradox.

Quantum annealers conventionally use forward annealing to generate heuristic solutions. Reverse annealing can potentially generate better solutions but necessitates an appropriate initial state. Ways to find such states are generally unknown or highly problem dependent, offer limited success, and severely restrict the scope of reverse annealing. We use a general method that improves the overall solution quality and quantity by feeding reverse annealing with low-quality solutions obtained from forward annealing. An experimental demonstration of solving the graph coloring problem using the D-Wave quantum annealers shows that our method is able to convert invalid solutions obtained from forward annealing to at least one valid solution obtained after assisted reverse annealing for 57% of 459 random Erdos–Rényi graphs. Our method significantly outperforms random initial states, obtains more unique solutions on average, and widens the applicability of reverse annealing. Although the average number of valid solutions obtained drops exponentially with the problem size, a scaling analysis for the graph coloring problem shows that our method effectively extends the computational reach of conventional forward annealing using reverse annealing.

Under the quaternion group, Q8, spin helicity emerges as a crucial element of the reality of spin and is complementary to its polarization. We show that the correlation in EPR coincidence experiments is conserved upon separation from a singlet state and distributed between its polarization and coherence. Including helicity accounts for the violation of Bell’s Inequalities without non-locality, and disproves Bell’s Theorem by a counterexample.

Doping titanium dioxide has become a strategy for enhancing its properties and reducing its recombination issues, with the aim of increasing its efficiency in photocatalytic processes. In this context, this work studied its deposition over glass substrates using a sol–gel dip coating methodology. The effect of doping TiO2 with Zirconium cations in low molar concentrations (0.01, 0.05, 0.1%) in terms of its structural and optical properties was evaluated. The structural characterization confirmed the formation of amorphous thin films with Zr introduced into the TiO2 cell (confirmed by XPS characterization), in addition to increasing and defining the formed particles and their size slightly. These changes resulted in a decrease in the transmittance percentage and their energy band gap. Otherwise, their photocatalytic properties were evaluated in hydrogen production using ethanol as a sacrificial agent and UV irradiation. The hydrogen evolution increased as a function of the Zr doping, the sample with the largest Zr concentration (0.1% mol) being the most efficient, evolving 38.6 mmolcm−2 of this gas. Zr doping favored the formation of defects in TiO2, being responsible for this enhancement in photoactivity.

Degradable and high-barrier plastic packaging materials draw more attention with the development of a social economy and the demands of environmental protection. In this study, poly(propylene carbonate phthalate) (PPC-P) and poly(butylene adipate-co-terephthalate) (PBAT) blends with different ratios were designed and prepared, marked as PPC-P/PBAT. Chain extenders were introduced into the blends, and the mechanical properties, thermal properties, and barrier properties of the composites were studied. The 75PPC-P/PBAT with 2% extenders represent the best performance. The addition of the chain extender has significantly improved the thermal stability and tensile elongation of PPC-P/PBAT. On this basis, the PPC-P/PBAT composite film was coated with PVA and borax using the dipping and pulling method. The oxygen barrier properties have been further improved for the composite film with a coating layer. Considering the characteristics of biodegradability and a high-barrier property, the 75PPC-P/PBAT/2MDI@Gly blend coated with 2 wt% PVA and 3 wt% borax exhibits potential as a superior food/pharmaceutical plastic packaging material with excellent tensile and barrier properties.