Search Results (131)

In this investigation, we explore previously unknown relations between natural constants by taking the following steps: (1) We discard Dirac’s constant ℏ from the universal man-made constants of physics, which we redefine in terms of Planck’s constant h. (2) Working in the SI system of units, we determine Newton’s gravitational constant G from Boltzmann’s constant $k_{\mathrm{B}}$ and the elementary charge e, recognizing the entropy of matter as their common underlying characteristic. (3) By comparing the mass of 1 mole of electrons to the h-defined Planck mass $M_{\mathrm{P}}$, we deduce nature’s own molar constant ($\simeq$0.1 mol) that contains a ‘reduced Avogadro number’ ${\aleph }_{\mathrm{A}}=N_{\mathrm{A}}/f_{\mathrm{A}}$ of particles, where $N_{\mathrm{A}}$ is Avogadro’s number and $f_{\mathrm{A}}\simeq 10$ is the associated Avogadro factor. (4) From the new effective gravitational constant $G_{★}\equiv 4\pi {\epsilon }_{0}G$, where ${\epsilon }_0$ is the vacuum permittivity, we obtain MOND’s universal constant ${\mathcal{A}}_0$ and its critical acceleration $a_0$, recognizing the Newtonian source of gravity as the common underlying characteristic and repudiating the need for a principle of equivalence of masses. (5) We derive the gravitational coupling constant ${\mathsf{\alpha }}_{\mathrm{g}}$ solely from ${\aleph }_{\mathrm{A}}$. (6) We adopt the measured value of the h-defined fine-structure constant (FSC) $\mathsf{\alpha }$ and the value of ${\mathsf{\alpha }}_{\mathrm{g}}$ (or, equivalently, nature’s ${\aleph }_{\mathrm{A}}$), and we determine the relative ratio ${\mathsf{\beta }}_{\mathrm{g}}={\mathsf{\alpha }}_{\mathrm{g}}/\mathsf{\alpha }$ precise to 10 significant digits. (7) We derive the relative strong ratio ${\mathsf{\beta }}_{\mathrm{s}}={\mathsf{\alpha }}_{\mathrm{s}}/\mathsf{\alpha }$ directly from the Avogadro factor $f_{\mathrm{A}}$. (8) We determine the coupling constants of weak and strong interactions (${\mathsf{\alpha }}_{\mathrm{w}}$ and ${\mathsf{\alpha }}_{\mathrm{s}}$, respectively) in terms of the FSC $\mathsf{\alpha }$. (9) The relation ${\mathsf{\alpha }}_{\mathrm{w}}=\sqrt{\mathsf{\alpha }}$ leads to a determination of the mass of the W boson $m_{\mathrm{W}}$ from the measured values of $\mathsf{\alpha }$ and the reduced Fermi constant $G_{\mathrm{F}}^0$. (10) Using the Planck mass as a principal constant ($M_{\mathrm{P}}={\aleph }_{\mathrm{A}}{m}_{\mathrm{e}}$, where $m_{\mathrm{e}}$ is the electron mass), we obtain new classical definitions of $h,\mathsf{\alpha }$, and the Compton radius $r_{\mathrm{c}}$; and we reformulate in a transparent, geometrically clear way several important QED equations, as well as the extended Planck system of units itself. We discuss the implications of these results, and we pave a way forward in exploring the unification of the fundamental forces of nature. Full article

We develop a first-principles theory that bridges three-dimensional (3D) confinement and two-dimensional (2D) in-plane correlations in counterion layers at oppositely charged interfaces. The system is controlled by two independent coupling constants. While a 3D parameter ($\gamma$) for perpendicular localization varies with the strength and direction of the applied electric field, a 2D parameter ($\Gamma$) for lateral correlations depends solely on system-specific conditions. This independence allows for strongly coupled yet noncrystalline liquid states. Our theoretical framework is based on a hybrid of density functional and statistical field theory, thereby yielding an extended Percus relation that, unlike its conventional counterpart for uniform 2D liquids, is valid for the spatially inhomogeneous density profiles. This extension is critical, as it establishes a direct connection between the 3D confinement and the resulting 2D in-plane structure. Numerical investigations of this relation reveal key in-plane structural features in the strong 3D coupling limit ($\gamma \to \infty$): a geometric length scale, the minimal inter-particle separation ($d_{\min }$), governs both the first peak of the radial distribution function and the wavelength ($\lambda$) of its oscillatory tail. These findings clarify that in-plane order in these strongly coupled counterion liquids is determined by a geometric constraint rather than any crystalline symmetry. Full article

In this study, the chemical solubility (stability) of yttria-partially stabilized zirconia (2.3Y-TZP) dental ceramics, both glazed (Group 2) and non-glazed samples (Group 1), was evaluated using a modified testing protocol based on ISO 6872:2024. Chemical stability was assessed by measuring ion release with inductively coupled plasma mass spectrometry (ICP-MS) and by analyzing phase composition with X-ray diffraction (XRD). While ISO 6872 prescribes chemical stability testing in a 4 wt.% aqueous acetic acid solution at 80 °C for 16 h, the exposure duration in this study was extended to 768 h (32 days) to allow a more accurate determination of long-term solubility behavior. Additionally, the surface roughness parameters (R_a, R_max, R_z, S_a, S_q) were analyzed and evaluated before and after solubility testing. Kinetic analysis revealed that degradation followed a near-parabolic rate law, with power-law exponents of n = 2.261 for Group 1 and n = 1.935 for Group 2. The corresponding dissolution rate constants were 3.85 × 10⁻⁵ µgⁿ·cm⁻²ⁿ·h⁻¹ for Group 1 and 132.3 µgⁿ·cm⁻²ⁿ·h⁻¹ for Group 2. XRD results indicated that the long exposure to acetic acid induced a partial phase transformation of zirconia from the tetragonal to the monoclinic phase. Under prolonged acetic exposure, the glaze layer on 2.3Y-TZP exhibited significantly higher dissolution, whereas the zirconia (polished, unglazed) showed low ion release. The temporal change in the total amount of dissolved ions was statistically analyzed for Group 1 and Group 2. The samples showed a strong correlation, but ANOVA confirmed significant differences between them. Full article

A PI control approach grounded in an optimized improved whale algorithm is devised to tackle the characteristics of multivariable, nonlinear, strong coupling, and uncertain and fluctuating wind speeds in electric variable pitch systems. In the improved whale algorithm optimization algorithm, the reverse learning mechanism is utilized within the population initialization stage, the nonlinear inertial weight coefficient is introduced in the global and local search processes of whale predation, and the convergence factor is updated by the exponential function, which effectively addresses the issue of sluggish convergence speed and low convergence efficiency of the whale optimization algorithm. The position control of the electric variable pitch system is implemented with the application of the improved whale optimization algorithm. According to the performance index of the position ring, the appropriate objective function is established, and the adaptive control of the position ring is realized through the adaptive adjustment of PI parameters. The simulation outcomes demonstrate that the PI control, which is founded on an improved whale optimization algorithm, is superior to the PI control based on the whale optimization algorithm in dynamic and steady performance. When the load torque changes, using PI control based on the improved whale optimization algorithm, the pitch angle reaches the steady-state value in 0.06 s without overshoot, while using PI control based on the whale optimization algorithm, the pitch angle reaches the steady-state value in 0.09 s with a maximum overshoot of 2.4°. When the load torque is constant, PI control based on the improved whale optimization algorithm can achieve pitch angle tracking in 0.16 s, while PI control based on the whale optimization algorithm can achieve pitch angle tracking in 0.48 s. Full article

1,4-Thiazine S,S-dioxide 1, the cis- and trans-isomers 2 and 3 of its precursor 2,6-diethoxy-1,4-oxathiane S,S-dioxide, and diethyl 2,3-dihydro-1,4-thiazine-3,5-dicarboxylate S,S-dioxide 4 have been fully characterised, both in solution by ¹H and ¹³C NMR and in the solid state by X-ray diffraction. Simulation has been used to model the unexpectedly complex ¹H NMR spectra and arrive at a full assignment of all chemical shifts and coupling constants. The crystal structures of both 1 and 4, which adopt, respectively, boat and half-chair conformations, are dominated by strong NH to O=S hydrogen bonding leading to chains of molecules. In the case of 4, the NMR data point to an equatorial position of the C(2)-ester group in solution, while in the crystal, this adopts an axial orientation. Compounds 2 and 3 adopt chair conformations both in solution and in the solid state with ring inversion on the NMR timescale leading to unexpected simplification of the spectra in the case of 3. Full article

This study presents a convex optimization framework for beam synthesis in Square Kilometre Array low-frequency radio telescope stations configured in a sunflower-like layout. The method minimizes the peak sidelobe level by computing an optimized set of beamforming weights, enabling precise control of the main beam while preserving angular resolution. The framework is validated through full-wave electromagnetic simulations based on detailed physical models of the antenna elements and station geometry. Compared to conventional beamforming employing constant unitary real weights, the optimized solutions yield a significant reduction in sidelobe levels, with only a minimal impact on directivity. These benefits are particularly evident at frequencies where mutual coupling between array elements is strong, confirming the suitability of the proposed approach for dense radio astronomy arrays. Full article

Parkinson’s disease (PD) is a neurodegenerative disorder marked by the progressive loss of dopaminergic neurons in the nigrostriatal pathway. The dopamine active transporter (DAT), a key protein involved in dopamine reuptake, serves as a selective biomarker for dopaminergic terminals in the striatum. DAT binding has been extensively studied using in vivo imaging techniques such as Single-Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET). To support the design of new radiotracers targeting DAT, we employ Quantitative Structure–Activity Relationship (QSAR) analysis on a structurally diverse dataset composed of 57 compounds with known affinity constants for DAT. The best-performing QSAR model includes four molecular descriptors and demonstrates robust statistical performance: R² = 0.7554, Q²_LOO = 0.6800, and external R² = 0.7090. These values indicate strong predictive capability and model stability. The predicted compounds are evaluated using a docking methodology to check the correct coupling and interactions with the DAT. The proposed approach—combining QSAR modeling and docking—offers a valuable strategy for screening and optimizing potential PET/SPECT radiotracers, ultimately aiding in the neuroimaging and early diagnosis of Parkinson’s disease. Full article

The deflagration-to-detonation transition (DDT) is a critical process for achieving reliable ignition in detonation-based propulsion systems, such as Rotating Detonation Engines (RDEs). This study experimentally investigates the effect of spatial variations in blockage ratio (BR) on flame acceleration and detonation onset within a modular pre-detonator. Three DDT device configurations (converging, constant, and diverging) were designed to have an identical average BR of 0.5 and were tested over equivalence ratios ranging from 0.64 to 1.6. High-speed imaging, pressure transducers, and schlieren visualization were employed to characterize flame propagation velocity, pressure evolution, and exit wave structures. The converging configuration consistently promoted earlier detonation onset and higher success rates, especially under fuel-rich conditions (ϕ = 1.6), while the diverging configuration failed to initiate detonation in all cases. Enhanced flame compression in the converging layout led to strong coupling between the shock and reaction fronts, facilitating robust detonation formation. These findings indicate that the spatial distribution of BR, rather than average BR alone, plays a decisive role in DDT performance. This work offers validated design insights for optimizing pre-detonator in RDE applications. Full article

Biosurfactants have emerged as promising agents for environmental remediation due to their ability to complex, chelate, and remove heavy metals from contaminated environments. This review evaluates their potential for recovering critical minerals from waste materials to support renewable energy production, emphasizing the role of biosurfactant–metal interactions in advancing green recovery technologies and enhancing resource circularity. Among biosurfactants, rhamnolipids demonstrate a high affinity for metals such as lead, cadmium, and copper due to their strong stability constants and functional groups like carboxylates, with recovery efficiencies exceeding 75% under optimized conditions. Analytical techniques, including Inductively Coupled Plasma Mass Spectrometry (ICP-MS), Fourier-Transform Infrared spectroscopy (FTIR), and Scanning Electron Microscopy (SEM), are instrumental in assessing recovery efficiency and interaction mechanisms. The review introduces a Green Chemistry Metrics Framework for evaluating biosurfactant-based recovery processes, revealing 70–85% lower Environmental Factors compared to conventional methods. Significant research gaps exist in applying biosurfactants for extraction of metals like lithium and cobalt from batteries and other waste materials. Advancing biosurfactant-based technologies hold promise for efficient, sustainable metal recovery and resource circularity, addressing both resource scarcity and environmental protection challenges simultaneously. Full article

Two organic–inorganic materials (TMAA)₂[CoCl₄] (1) and (TMAA)₂[MnCl₄] (2) (TMAA = N,N,N-trimethyl-1-adamantylammonium hydroxide) were synthesized and characterized. It was found that both compounds exhibit first-order structural phase transition at high-temperature regions. As the temperature approaches the phase transition point, significant abnormal changes were observed in the dielectric properties and χ_MT values of compounds 1 and 2. This phenomenon strongly highlights the dielectric bistable and spin bistable properties of compounds 1 and 2. Further research shows that the dielectric constants of the compounds undergo significant changes upon the application of an external magnetic field, providing strong evidence for the existence of magnetic–dielectric coupling effects within compounds 1 and 2. Full article

The phenomenon of augmented gravity on the scale of galaxies, conventionally attributed to dark matter halos, is shown to possibly result from the incremental growth of galactic masses and radii over time. This approach elucidates the cosmological origins of the acceleration scale $a_0\approx c{H}_0/2\pi \approx {10}^{-10}$ ms⁻² at which galaxy rotation curves deviate from Keplerian behavior, with no need for new particles or modifications to the laws of gravity, i.e., it constitutes a new explanatory path beyond Cold Dark Matter (CDM) and Modified Newtonian Dynamics (MOND). Once one formally equates the energy density of the universe to the critical value ($\rho ={\rho }_c$) and the cosmic age to the reciprocal of the Hubble parameter ($t=H^{-1}$), independently of the epoch of observation, the result is the Zero-Energy condition for the cosmic fluid’s equation of state, with key repercussions for the study of dark energy since the observables can be explained in the absence of a cosmological constant. Furthermore, this mass-energy evolution framework is able to reconcile the success of CDM models in describing structure assembly at $z\lesssim 6$ with the unexpected discovery of massive objects at $z\gtrsim 10$. Models that feature a strong coupling between cosmic time and energy are favored by this analysis. Full article

A hybrid material composed of IRMOF-3 and ZnO (IRMOF-3/ZnO) was synthesized to enhance photocatalytic methylene blue (MB) degradation under visible-light irradiation. Scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and diffuse-reflectance UV-Vis analyses confirmed the successful integration of ZnO into the IRMOF-3 framework. Compared with unmodified IRMOF-3, the hybrid demonstrated superior MB decomposition, as evidenced by faster reaction rate constants and shorter half-lives. Monitoring the MB absorbance at 670 nm (λ_max) revealed more pronounced colorant removal when IRMOF-3/ZnO was exposed to a visible-light source. Diffuse-reflectance UV-Vis spectroscopy showed that IRMOF-3 has a band gap of 2.7 eV, whereas IRMOF-3/ZnO exhibits a slightly higher band gap of 2.8 eV. This modest shift, coupled with the strong interaction between the ZnO semiconductor and the MOF’s amine functionalities, enabled two distinct energy-transfer pathways: intermolecular transfer from IRMOF-3 linkers (acting as visible-light antennas) to ZnO, and intramolecular transfer from Zn to IRMOF-3. Together, these pathways generated abundant free radicals for efficient dye degradation. Despite the necessity for careful synthesis protocols and control of operating conditions to preserve the MOF structure and optimize ZnO loading, the IRMOF-3/ZnO hybrid shows promise as a robust, cost-effective photocatalyst for water-pollutant remediation, taking advantage of the more abundant visible region of solar light. Full article

The CMS experiment provides measurements of the soft and hard QCD processes using samples of proton–proton and AA collisions collected at different energies. Measurements include particle multiplicity, particle momentum spectra and correlations, jet properties and production rates, and are compared with predictions of theoretical models at leading, next-to-leading and next-next-to-leading QCD fixed order accuracy. The data in combination with measurements obtained by other experiments are used to measure the strong coupling constant and for PDF constraints. Full article

The precise estimation of influential parameters in adsorption is a key point in conducting simulations for the sensitivity analysis and optimal design of cooling systems. This study explores the critical role of a new type of granular activated carbon (GAC-208C) in adsorption refrigeration systems. By fitting experimental and numerical models to the thermophysical properties of GAC/methanol as a working pair, an advanced methodology is established for the thermal analysis of the adsorption bed, addressing the various operating conditions overlooked in prior studies. The physical properties of the studied carbon sample are determined in a laboratory using surface area and pore volume tests, thermal adsorption analysis, and weight loss. To determine the thermal properties of GAC/methanol, the adsorption process is experimentally tested inside an isolated heat exchanger. A three-dimensional (3D) model is created to simulate the procedure and then coupled with the particle swarm optimisation (PSO) algorithm in MATLAB. The optimal thermal parameters for adsorption are determined by minimising the mean square error (MSE) of the adsorption bed temperature between the numerical and experimental data. The laboratory studies yielded accurate results for the physical properties of GAC, including adsorption capacity, porosity, permeability, specific heat capacity, density, activation energy, and the heat of adsorption. The thermal analysis of the adsorption process identified the ideal values for the Dubinin–Astakhov equation constants, diffusion coefficients, heat transfer coefficients, and contact resistance. The numerical model demonstrated strong agreement with the experimental results, and the dynamic behaviour of pressure and uptake distribution showed good agreement with 1.2% relative error. This research study contributes to the improved estimation of adsorption parameters to conduct more accurate numerical simulations and design new adsorption systems with enhanced performance under different operating conditions. Full article

Redox-induced magnetic regulation in organic diradicals is distinctly attractive. In this work, taking nitroxide radicals as spin sources, we predict the magnetic properties of 9, 10-anthraquinone, 9, 10-phenaquone, 9, 10-diazanthracene and 9, 10-diazepine-bridged molecular diradical structures in which the couplers are prone to dihydrogenation reduction at positions 9 and 10. As evidenced at both the B3LYP and M06-2X levels of theory, the calculations confirm that the magnetic transitions between ferromagnetism and antiferromagnetism can take place for 9, 10-anthraquinone and 9, 10-diazanthracene-bridged diradicals after dihydrogenation. The differences in the magnetic behaviors and magnetic magnitudes of 9, 10-anthraquinone and 9, 10-diazanthracene-bridged diradicals before and after dihydrogenation could be attributed to their noticeably different spin-interacting pathways. As for 9, 10-phenaquone and 9, 10-diazepine-bridged diradicals, the calculated results indicate that the signs of their magnetic exchange coupling constants J do not change, but the magnitudes remarkably change after dihydrogenation. The connecting bond character and spin polarization are crucial in explaining the different magnetic magnitudes of these designed diradicals. In detail, shorter bonds and larger spin polarization are responsible for strong magnetic coupling. In addition, the diradical with an extensively π-conjugated structure can effectively promote magnetic coupling. The McConnell’s spin alternation rule is the key to understanding the observed ferromagnetism and antiferromagnetism of these diradicals. The work provides useful information for the rational design of redox-regulated magnetic molecular switches. Full article