Communications in Physics

Detailed studies of the response of the VATLY water Cherenkovdetector, a replica of those used in the ground array of the PierreAuger Observatory, are presented with emphasis on the response to lowamplitude signals. The method used is to detect decay electrons frommuons stopping in the water volume. Results include properties of the detection process as well as of the atmospheric cosmic ray flux.

Spilanthes acmella L. Murr is a medicinal herb with many valuable biological activities such as clearing heat, detoxifying, dissipating phlegm, antiseptic, pain relief, antifungal, anti-inflammatory... In this work, we used Spilanthes acmella L. Murr extract to synthesize silver nanoparticles to combine and enhance the activity of silver and Spilanthes acmella L. Murr extract in antibacterial and antifungal activities. The reaction parameters were investigated to find the most optimal conditions for synthesizing silver nanoparticles, such as AgNO3 volume, solution pH, and reaction temperature. UV-VIS absorption spectra were used to analyze the influence of the reaction parameters. The functional groups on the silver nanoparticles as well as the Spilanthes acmella L. Murr extract were found by infrared absorption (FTIR) spectroscopy. The crystal structure of the synthesized silver nanoparticles was determined by X-ray diffraction (XRD) spectroscopy. On the basis of the synthesized silver nanoparticles, the antifungal activity was investigated on the strains: A. flavus (Af), A. brasiliensis (Ab), C. Albicans (Ca), and antibacterial: Staphylococcus aureus (SA), Pseudomonas aeruginosa (PA) was performed to compare the activity of the antibiotic ampicillin 100 mg/mL.

The paper presents results of synthesizing Ag-Cu2O nanocomposites by one pot method. The characteristics, properties of Ag-Cu2O nanocomposites were determined by X ray diffraction, Field Emission Scanning Electron Microscopy (FESEM) and UV-Vis diffuse reflectance spectroscopy. The obtained results indicated that the crystalline size of Cu2O particles was about 38.36 nm while that of Ag particles was about 12 nm. The FESEM images showed tendency of agglomeration of Cu2O particles. The Ag nanoparticles were dispersed regularly on the surface of Cu2O particles. Due to modification by AgNO3­ salt solution, the Ag-Cu2O nanocomposites had a better ability to absorb light than the Cu2O particles and had a lower bandgap energy. Additionally, the Ag-Cu2O nanocomposites also had a higher photocatalytic activity than that of the Cu2O particles. The Ag-Cu2O nanocomposite is promising for water treatment application

A facile and controllable one-step atmospheric pressure microplasma method was employed to synthesize nitrogen-doped carbon quantum dots (N-CQDs) with tunable optical properties. The N-CQDs were characterized using Fourier transform infrared spectroscopy, high-resolution transmission electron microscopy, UV‒Vis absorption spectroscopy, and photoluminescence spectroscopy. HRTEM revealed uniformly distributed spherical nanoparticles with a graphite-like structure. FTIR confirmed effective nitrogen doping, enhancing chemical stability. UV‒Vis spectroscopy revealed redshifted absorption peaks, indicating improved electronic interactions and a reduced bandgap (4.05 eV) compared to those of undoped CQDs (4.18 eV). PL analysis revealed excitation-dependent emission and a significantly higher photoluminescence quantum yield (PLQY) of 33.09%. These results suggest that N-CQDs hold promise for applications in optoelectronics and bioimaging, providing a foundation for further optimization in future studies.

We report on the second-order phase transition of two-dimensional (2D) magnetic materials under the influence of random anisotropy in the context of the Blume-Capel model employing an effective field theory and the differential operator method. By analyzing the temperature dependence of magnetization, we thoroughly explore the second-order ferromagnetic-to-paramagnetic (FM-PM) phase transition at the critical temperature $T_C$. When the magnitude of the random anisotropy $D$ and its probability $p$ is sufficiently large, the magnetization equation becomes divergent and unsolvable at a critical temperature, indicating the emergence of a tricritical point and a first-order phase transition. Additionally, we produce a phase diagram for the second-order phase transition presenting the relation between the critical temperature and anisotropy amplitude at various probabilities.

We study the dynamics of a double-well BEC system subjected to oscillating dissipation. The macroscopic model is described within the mean-field approximation while noise effect due large reservoir fluctuation has been averaged out to zero. We chose a simple dissipative memory kernel to produce a time-dependant oscillating dissipation. Our numerically calculated phase-space and Lyapunov exponents shows enhances route to chaos as one increases driven dissipations amplitude.

Anatase Ti1-xCrxO2 nanowires with Cr3+ dopant contents ranging from x = 0 to 0.1 have been successfully synthesized by hydrothermal method. The nanowires were prepared from anatase titanium dioxide powder (TiO2), chrome nitrate (Cr(NO3)3), and sodium hydroxide (NaOH). The effect of the Cr3+ concentration and heat-treating temperature on structure, morphology of the synthesized Ti1-xCrxO2 samples has been studied by X-ray diffraction, scanning electron microscopy and Raman scattering. At low heat-treating temperature (≤ 600 oC), the samples exhibited anatase phase and in the Raman spectra of samples with x ≥ 0.01 exhibited a new series peak at 120, 236, 250, 292, 362, 430, 467 and 550 cm-1, which were assigned to the localized vibrational modes related to the complexes containing Cr3+ ion. But at high heat-treating temperature (1100 oC), the samples exhibited rutile phase, in the Raman spectra the above-mentioned peak series did not appear, instead of this, only observed shifting and broadening of characteristic Raman modes (Eg and M) for rutile TiO2 with increasing Cr3+ dopant content, which proves that the Cr3+ ions have replaced the Ti4+ ions in the rutile TiO2 host lattice. The lattice constants of both the rutile and anatase TiO2 crystallites have been hardly affected by Cr3+ ions dopant contents.

Recent studies of the tube model of protein have indicated that the free energy landscape of proteins is presculpted by symmetry of the protein backbone and geometrical constraints played by the hydrogen bonds. In this study, we investigate the role of amino acid sequences in the folding of proteins. We consider two models that are differed by sequence specificity: the tube HP model with hydrophobic (H) and polar (P) sequences, and the tube Go model with native-centric contact potentials. Monte Carlo simulations are carried out for two sequences of length of 48 amino acids, whose ground states are a three-helix bundle and a GB1-like structure.  The results show that folding inthe Go model is more cooperative than in the HP model. In the HP model the collapse transition and the folding transition are separated, whereas in the Go model the two transitions coincide.

CuO nanoparticles were synthesized by alcohol-assisted hydrothermal method at various pH values, using sodium hydroxide as a precursor for pH control. The chemical composition, morphological and structural properties of the obtained CuO nanoparticles were investigated by the Raman and energy-dispersive X-ray spectroscopies, the field-emission scanning electron microscopy, and the X-ray diffraction. The results reveal that although the pH value does not affect the formation of the CuO phase, it strongly influences the crystalline size, the morphology, and the particle-agglomeration level of CuO. The differences in the morphology and the crystalline size of CuO nanoparticles are ascribed to various H+/OH- ratios of the growth solution. Meanwhile, with the optimized particle size, the CuO nanoparticles-based sensor can be used as a potential candidate for CO and/or H2 detection.

In this paper, we show a unifying description to the dark matter and dark energy. This description does not demand dark energy with the anti-gravitational property. It also points out a lower limit of the average mass of the particles of cosmological energy (ordinary matter, dark matter and dark energy particles) \(\bar{m}\gg 54\) eV. The coincident problem between the density of dark energy and one of matter is a clear fact.