Peaks In Spectra Research Articles

A probability-constraint-based method based on the honey badger algorithm for wind estimation with coherent Doppler wind lidar

Coherent Doppler wind lidar (CDWL) has emerged as an effective tool for analyzing wind velocity distributions. It utilizes the peak frequency of the signal spectrum to determine wind velocity. However, accurate identification of the spectrum peak in low signal-to-noise ratio (SNR) environments is complicated by noise pollution. Enhancing CDWL performance involves correcting the spectrum in these challenging areas. Existing probability-constraint-based methods (PCBMs) require empirical parameter settings, limiting their adaptability across different Doppler wind lidar environments. This paper proposes and demonstrates a probability-constraint-based method based on the honey badger algorithm (PCBM-HBA). The gate moving average method (GMAM) based on the spectrum obtains the reference wind velocity as a constraint. The correlation coefficient between the inverted wind velocity value of PCBM and the reference wind velocity is used as the negative value of the fitness function to obtain the optimal parameter σ. Simulation results based on the American Standard Atmosphere Model show that PCBM-HBA can measure wind fields in areas with low SNRs, and the maximum detection range improves from 3.8 to 5.4 km. During the inversion of the measured signal, the PCBM-HBA improves the inversion results of wind velocity under different pulse conditions, and the inversion results of the PCBM-HBA with 50 accumulated pulses are better than those of the traditional method with 150 accumulated pulses, which enhances the applicability of the PCBM and improves the performance of the system.

Synergistic effects of gadolinium oxide into the matrix of zeolitic imidazolate frameworks (ZIFs) for supercapacitor applications

In this study, we synthesized ZIF-8, ZIF-67, Gd₀.₀₁/ZIF-8, & Gd₀.₀₁/ZIF-67 electrodes using the direct combination technique. Both electrodes are being used for energy storage devices. We extensively evaluated these nanocomposites using a variety of electrochemical methods, including retention analysis, galvanostatic charge-discharge (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). ZIF-8 exhibits a wide band gap of approximately 2.58 eV, suggesting its main absorption is of UV light. The peaks in the absorbance spectrum vary slightly in wavelength due to the presence of different metal centers. Peaks between 1400-1600 cm⁻1 indicate C–N stretching vibrations from the imidazolate linkers. Peaks between 1600-1700 cm⁻1 are associated with C=C stretching vibrations. ZIF-8 exhibits well-defined peaks in its XRD pattern, indicating a high level of crystallinity. Peaks can be observed at specific 2θ values, typically at 22.09°, 26.62°, 38.49°, and 47.27°, which correspond to the (110), (200), (211), and (220) planes. The calculated specific capacitances for ZIF-8 and ZIF-67 are 223.95 and 255.20 F/g. For Gd0.01/ZIF-8, & Gd0.01/ZIF-67 specific capacitances are 575.00 and 587.50 F/g. The ZIF-8, ZIF-67, Gd0.01/ZIF-8, & Gd0.01/ZIF-67 electrodes exhibited specific capacitances of (78.30, 192.59, 342.57, and 1164) F/g at current densities of 1 A/g from the GCD calculation. The retention plot of ZIF-8, ZIF-67, Gd0.01/ZIF-8, & Gd0.01/ZIF-67 electrode shows efficiency of 71%, 71%, 105% and 75%, respectively, indicating their suitability for supercapacitor applications.

Holmium ions influence in structural and optical properties of Aluminium Strontium-phosphate glasses for radiation shielding applications

This study details the synthesis of a novel series of Holmium-doped Aluminium Strontium-phosphate glass (HoAlSr- phosphate glass) composed of 55 P2O5 + 5 Al2O3 + 4 MgO + 5 NaF + 10 LiCO3 + 5 CaO + 10 SrCO3 + 5 ZnO + 1 Ho2O3 prepared by melt-quench method and its structural, optical, and physical properties are analysed. Powder −XRD verified its amorphous nature, FTIR shows the existence of large phosphate functional groups, Optical properties such as band gap energy was calculated by acquiring absorption spectra covering the UV, Vis, and NIR ranges. Obtained 3.02 eV optical band gap energy. The refractive index changing with increasing energy. Three peaks in the PL spectra corresponded to Ho3+ transitions: 5I8→ 5G6, 5I8→ 3K8, and 5I8→ 5F3. The glass conducted theoretical studies for radiation shielding properties based on several key parameters. Gamma radiation shielding parameters, including Mean Free path (MFP), Effective atomic number (Zeff), linear attenuation coefficient (LAC), and mass attenuation coefficient (MAC), were obtained with the use of the Phy-X program. MAC data show that when Compton scattering (CS) fluctuates in the intermediate photon energy zone (E > 3 MeV), the area of prominence of CS diminishes. They can cause pair production at higher energies, Compton scattering at intermediate energies, and the photoelectric effect at lower energies. The MFP values of glasses doped with HoAlSr- phosphate glass were shorter, indicating a higher level of shielding efficacy. In this study we are focusing on optical properties changes with presence of Holmium ions and its shielding property using Phy-x software. In this research discovered that the synthetic material has high shielding qualities and can be a valuable shield in environments where X-rays are present. So it will be beneficial at X-ray prompted environment

Exploring the Differences of Chemical Components of Citri Reticulatae Pericarpium Powder Decoction and Pieces Decoction Based on UHPLC-Q-Exactive Orbitrap MS/MS and Network Pharmacology.

Taking Citri Reticulatae Pericarpium (CRP) as an example, it is proved that there are differences between the powder decoction and pieces decoction of traditional Chinese medicine (TCM). In this study, an ultra-high performance liquid chromatography quadrupole exactive orbitrap MS/MS (UHPLC-Q-Exactive Orbitrap MS/MS) method was established to characterize 80 chemical components of CRP. The content of components was compared based on extraction rate, alcohol solubility rate, and mass spectrum peak area. The result showed that the content in CRP powder decoction was generally higher than that in CRP pieces decoction. The principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) were used to distinguish between the two decoctions. In addition, cardiovascular diseases (CVDs) were used as a model to investigate whether the increased content of components has practical significance. Network pharmacology screened five core targets of CRP in CVDs. The results of molecular docking indicated that the binding energies were all ≤ -5.0kcal/mol between effective compounds (M34, M57, M80, etc.) and key targets (Akt1, SRC, ESR1, EGFR, and PTGS2) with good affinity. These results provide an important reference for further development and use of CRP powder decoction.

Hexagonal ZnO microdisk grown by mist chemical vapor deposition on c-plane sapphire substrate and lasing actions

Abstract Hexagonal ZnO microdisks were grown by mist chemical vapor deposition (mist-CVD) for 6 h. The microdisks when viewed from the top were typically hexagonal with diameters of a few micrometers, and their typical three-dimensional shape was a hexagonal pyramid. Sharp peaks appeared in the room-temperature photoluminescence (PL) spectra observed from a single hexagonal ZnO microdisk under high optically pumped conditions, and they are assumed to correspond to lasing actions. We also examined the temperature dependence of these sharp peaks in the PL spectra.


Array Optimization for a Wave Energy Converter with Adaptive Resonance Using Dual Bayesian Optimization

A novel Dual Bayesian optimization strategy is formed for an array of wave energy converters with adaptive resonance to maximize the annual performance through the energy conversion processes from irregular waves to electricity. A wave energy converter with adaptive resonance changes the natural frequency of power take-off dynamics for varying irregular waves, resulting in the maximum annual energy production. The first step of the two-step Dual Bayesian optimization determines the geometric layout of the array, which maximizes the first energy conversion to the total array excitation for irregular waves occurring annually. The second step optimizes the operational parameters of individual wave energy converters in the optimized array to maximize the power generation in varying sea states through simultaneous conversion to mechanical and electrical energy. The coupled hydrodynamics are solved in the frequency domain, and the power performance is evaluated by solving the Cummins’ equation in the time domain extended for multiple floating bodies, each strongly coupled with nonlinear power take-off dynamics. The proposed method is applied to a surface-riding wave energy converter, already optimized for single unit operation at individual sea states. Investigating two array layouts, linear and random, the optimized arrays after Step 1 increase the excitation spectral area by up to 40% relative to the single unit operation, indicating the synergy enhancing the first energy conversion. Subsequently, the dual-optimized linear layout attained a q-factor up to 1.13 in commonly occurring sea states, achieving improved average power generation in 60% of the evaluated sea states. The performance of the random layout exhibited the average power fluctuating along the wave spectra with a peak q-factor of 1.07. The individual adaptive resonance is confirmed in the optimized arrays, such that each surface-riding wave energy converter of both layouts adaptively resonates with the peak of the wave excitation spectra, maximizing the power generation for the different irregular waves.

Validation of GEANT4 simulation for active materials interrogation using nuclear resonance fluorescence

This study validates the GEANT4 simulation toolkit's effectiveness in modeling Nuclear Resonance Fluorescence (NRF) for Non-Destructive Assay (NDA) applications, focusing on isotopes 11B and 238U, which exhibit distinct NRF characteristics. Using experimental data from the High-Intensity γ-ray Source (HIγS) facility, the study benchmarks GEANT4's capability in simulating critical NRF interactions, such as spectra peak positions, angular distributions, and yield dependencies on target thickness. For 11B, GEANT4 successfully replicated NRF peaks at 2125, 4440, and 5020 keV, achieving alignment within ±1% of experimental values. For 238U, simulations reproduced NRF yield saturation as target thickness increased, validating the toolkit's handling of self-absorption and scattering effects, which are critical for applications involving high-density, shielded materials. These findings confirm GEANT4's robustness in simulating NRF phenomena, making it suitable for designing advanced NDA systems for security applications where isotope-specific detection and effective shielding penetration are essential. The validated toolkit provides a reliable foundation for developing accurate, efficient, and secure nuclear detection technologies.

Synthesis, Structural Aspects, Magnetic, and Adsorption Properties of a Dinuclear Cu (II) Complex Derived From Mixed Ligand Approach

ABSTRACTA dinuclear copper complex, [Cu2(teaH)(pNBA)2(H2O)2]·MeOH·pNBH (1) (where teaH3 = triethanolamine, pNBH = 4‐nitro‐benzoic acid, and pNBA = 4‐nitro‐benzoate) has been prepared and structurally characterized. In 1, there is an interesting intermolecular structure that is shown as a tetramer copper connected in chain‐like motif. In the UV‐Vis spectrum, higher absorbance at 267 nm is referred to n → π* transition, coupled with a weak peak at 500 nm, indicating another transition, which is specified as metal‐to‐ligand charge transfer. The higher intensity peak in the photoluminescence spectrum is marked as the absorption of energy required for the excitation of electrons, whereas lower intensity peaks show the emission of energy, which describes d‐d transitions of Cu (II) electrons due to d9 configuration. Complex 1 was explored for the adsorption of methylene blue (MB) dye, with the maximum adsorption as 101.07 mg/g, whereas the removal efficiency was estimated to be 81.05%. In conformity with the kinetic studies, the adsorption process proceeded via a Pseudo‐first‐order kinetic model. The incorporation of mixed ligands such as teaH3 and pNBH in 1 tends to increase the dimensionality that led to increased MB adsorption. The plausible mechanism behind the adsorption was favored by hydrogen‐bonding, electrostatic, π–π, and n–π* interactions, operating between the dye and complex 1. Further, the H‐bonding and these interactions provided stability to the complex, and an improved dye adsorption was observed even during the 2nd and 3rd recyclability experiments. Additionally, complex 1 corroborated remarkable stability after dye adsorption, allowing for up to four recycling turns. The magnetic study revealed antiferromagnetic coupling between the two magnetic centers with a singlet ground state (S = 0).

The effect of low energy high-dose X-ray irradiation on the performance of CdZnTe detector

The paper investigated the irradiation damage of CZT detectors caused by high flux an X-ray from X-ray tube operated at a tube voltage of 140 kV and an accumulated dose of 130 kGy. Deep-level transient spectroscopy (i-DLTS) was employed to characterize the defects. Four types of irradiation-induced defects were identified, corresponding to the energy levels at Ec-0.1eV, Ev+0.17eV, Ev+0.27eV and Ec-0.55eV, which are associated with the point defects, InCd+/0, VCd-/0, VCd2−/− and TeCd2+/+ respectively. After the irradiation, the concentration of VCd-/0 changed from 5.63 × 1012 cm−3 to 3.30 × 1013 cm−3 and VCd2−/− increased from 1.13 × 1012 cm−3 to 1.88 × 1013 cm−3. The resistivity of all samples showed an upward trend after the irradiation, with the most significant change observed in sample 1, where it doubled from 1.09 × 1011 Ω cm to 1.94 × 1011 Ω cm. However, the energy resolution for the spectrum peak of 241Am (59.5 keV) decreased from 6.2% to 10.7% and the signal noise to ratio decreased from 42.24 to 27.33 when irradiated from anode. The counting performance of the photon counting module decreased by approximately 1.81% after irradiation on the cathode side.

PEAKO and peakTree: tools for detecting and interpreting peaks in cloud radar Doppler spectra – capabilities and limitations

Abstract. Cloud radar Doppler spectra are of particular interest for investigating cloud microphysical processes, such as ice formation, riming and ice multiplication. When hydrometeor types within a cloud radar observation volume have different terminal fall velocities, they can produce individual Doppler spectrum peaks. The peaks of different particle types can overlap and be further broadened and blended by turbulence and other dynamical effects. If these (sub-)peaks can be separated, properties of the underlying hydrometeor populations can potentially be estimated, such as their fall velocity, number, size and to some extent their shape. However, this task is complex and dependent on the operation settings of the specific cloud radar, as well as atmospheric dynamics and hydrometeor characteristics. As a consequence, there is a need for adjustable tools that are able to detect peaks in cloud radar Doppler spectra to extract the valuable information contained in them. This paper presents the synergistic use of two algorithms used for analyzing the peaks in Doppler spectra: PEAKO and peakTree. PEAKO is a supervised machine learning tool that can be trained to obtain the optimal parameters for detecting peaks in Doppler spectra for specific cloud radar instrument settings. The learned parameters can then be applied by peakTree, which is used to detect, organize and interpret Doppler spectrum peaks. The application of the improved PEAKO–peakTree toolkit is demonstrated in two case studies. The interpretation is supported by forward-simulated cloud radar Doppler spectra by the Passive and Active Microwave TRAnsfer tool (PAMTRA), which are also used to explore the limitations of the algorithm toolkit posed by turbulence and the number of spectral averages chosen in the radar settings. From the PAMTRA simulations, we can conclude that a minimum number of n = 20–40 spectral averages is desirable for Doppler spectrum peak discrimination. Furthermore, small liquid peaks can only be reliably separated for eddy dissipation rate values up to approximately 0.0002 m2 s−3 in the simulation setup which we tested here. The first case study demonstrates that the methods work for different radar systems and settings by comparing the results for two cloud radar systems which were operated simultaneously at a site in Punta Arenas, Chile. Detected peaks which can be attributed to liquid droplets agree well between the two systems, as well as with an independent liquid-predicting neural network. The second case study compares PEAKO–peakTree-detected cloud radar Doppler spectrum peaks to in situ observations collected by a balloon-based holographic imager during a campaign in Ny-Ålesund, Svalbard. This case demonstrates the algorithm toolkit's ability to identify different hydrometeor types but also reveals its limitations posed by strong turbulence and a low n. Despite these challenges, the algorithm toolkit offers a powerful means of extracting comprehensive information from cloud radar observations. In the future, we envision PEAKO–peakTree applications on the one hand for interpreting cloud microphysics in case studies. The identification of liquid cloud peaks emerges as a valuable asset, e.g., in studies on cloud radiative effects, in seeder–feeder processes, or for tracing vertical air motions. Furthermore, the computation of the moments for each subpeak enables the tracking of hydrometeor populations and the observation of growth processes along fallstreaks. On the other hand, PEAKO–peakTree applications could be extended to statistical evaluations of longer data sets. Both algorithms are openly available on GitHub, offering accessibility for the scientific community.

The effect of D[formula omitted] partial pressure, deposition rate, and sample temperature on D retention in W codeposited layers

Hydrogen-isotope (HI) fuel retention in the walls of magnetic fusion devices must be minimized to achieve tritium self-sufficiency and for safety considerations. Retention in codeposited layers (i.e., layers formed from eroded material while simultaneously exposed to HIs) is projected to be a dominant source. This work investigates retention in tungsten (W)–deuterium (D) codeposited films as a function of D2 partial pressure. Tungsten films were deposited onto quartz substrates via magnetron sputtering in an Ar-D2 mixed background with the D2 partial pressure, pD2, varied from 0.13 to 1.6 Pa; the substrate temperature, Ts, varied from 310 K to 623 K; and the W deposition rate, rd, varied from ∼1.0 to 4.2×1019 m−2s−1. After deposition, D release was measured using thermal desorption spectroscopy (TDS). For films deposited at Ts∼ 310 K, D/W increased from 0.13 to 0.44 Pa, was constant to 0.89 Pa, and decreased at 1.6 Pa. However, the TDS spectra for films at all pD2 showed a similar distribution of D in traps, with a single release peak at 400–700 K. For films with pD2 = 0.89 Pa, D/W decreased exponentially with increasing Ts, in agreement with the Ts scaling in the literature, while the release peak in the TDS spectra shifted to higher desorption temperatures. For films deposited near room temperature, the measured D/W ratio decreased by 3× as rd increased, in agreement with the rd−0.8 scaling in the literature, while the tail of the D release increased from 700 to 1200 K for the higher rd. Hence, retention mitigation strategies for ITER (e.g., baking of the vacuum vessel at 493 K) may not be sufficient, especially for films formed with high rd.

Laser-Assisted Field Evaporation of Chromia with Deep Ultraviolet Laser Light.

In this work, samples of chromia (Cr2O3) scale have been prepared for atom probe tomography and field evaporated with deep ultraviolet laser light (258 nm wavelength). The investigated range of laser energies spans more than three orders of magnitude between 0.03 and 90 pJ. Furthermore, the effects of detection rate and temperature were investigated. Simultaneous voltage and laser pulses were employed on additional needle specimens to reduce the standing voltage and minimize background noise during the measurement. Smooth evaporation with minimal mass spectrum peak tails was maintained over the whole range of measurement parameters. High laser energies result in significant underestimation of the oxygen content. Only laser energies below 1 pJ resulted in measured values near the expected oxygen content of 60 at%, the closest being about 58 at%.

SERS-Encoded Nanoprobes Based on Silver-Coated Gold Nanorods for Cell Sorting.

Optically-encoded probes have great potential for applications in the fields of biosensing and imaging. By employing specific encoding methods, these probes enable the detection of multiple target molecules and high-resolution imaging within the same sample. Among the various encoding methods, surface-enhanced Raman scattering (SERS) spectral encoding stands out due to its extremely narrow linewidth. Compared to fluorescence spectral encoding, SERS encoding significantly reduces crosstalk between adjacent peaks, thereby achieving a larger encoding capacity and enabling multi-channel parallel analysis. This article presents the design and construction of two novel sets of SERS-encoded probes based on noble metal core-shell nanostructures. Two different encoding strategies are successfully applied to encode the SERS spectra of the probes: 1D encoding based on the wavenumber of characteristic peaks in the SERS spectrum, and 2D encoding combining both wavenumber and intensity of characteristic peaks in the SERS spectrum. In addition, this study also demonstrates the potential application of 1D encoded probes in cell sorting. These studies verify the feasibility of applying these two encoding methods to SERS core-shell probes and provide new insights into the construction of optically encoded probes.

Unraveling the Facet-Dependent Surface Chemistry at Molecular Scale: Photoassisted Oxidation of InP Nanocrystals.

The facet-dependent surface chemistry of nanocrystals (NCs) provides fundamental insights into chemical reactivities, which are critical for obtaining precise control over the NC surface. In this study, by obtaining InP NCs with well-defined {111} and {110}/{-1-1-1} facets (tetrahedrons and tetrapods, respectively) capped with chloride-oleylamine ligands, the previously underinvestigated facet-dependent surface chemistry of III-V materials is explored. Solid-state and solution NMR analyses show that InP tetrahedrons, with their smaller surface heterogeneity (single facet composition and lesser edge/vertex contribution) and stronger Lewis acidity, exhibit narrow 31P and 115In resonances as well as deshielded 13C signals of α-carbon adjacent to the NH2 group of oleylamine. As a result, InP tetrahedra exhibit strong ligand binding and a notable presence of less-mobile oleylamine ligands on the surface, leading to the blocking of access to external species. This is also consistent with the minimal blue shift of the first excitonic peak in absorption spectra and the strong resistance to photoassisted surface oxidation of InP tetrahedrons. Our findings, supported by solid-state/solution NMR, FT-IR, and XPS analyses, highlight the significance of facet-dependent reactivities to surface ligands and, thus, atmospheric moieties, enhancing the potential of III-V NCs in various optoelectronic applications.

Double Resonance of Electromagnetically Induced Transparency of Rydberg Atom in Counter-Propagating Configuration

The double resonance phenomenon of EIT is studied through the ladder three-level Rydberg system. A probe laser with the wavelength λp=852.35 nm is used to coupling the ground state 6S1/2 to the middle state 6P3/2, and a coupling laser with the wavelength λc=509.08 nm is implemented to couple the state 6P3/2 to the Rydberg state 62D5/2. A special optical scheme is designed, in which the co-propagating and counter-propagating configurations are both used. As a result, the double resonance of electromagnetically induced transparency (EIT) with the Rydberg atom is observed. By comparing the distance between the double peaks, it is found that the double resonance phenomenon comes from the Doppler effect, and the distance between the two resonance peaks in the absorption spectrum is related to the detuning of the resonant lasers.

Quantitative Analysis of Amorphous Form in Indomethacin by Near Infrared Spectroscopy Combined with Partial Least Squares Regression Analysis.

Indomethacin (INDO) is a synthetic non-steroidal antipyretic, analgesic, and anti-inflammatory drug that commonly exists in both amorphous and crystalline states. Its amorphous state (A-INDO) is utilized by pharmaceutical companies as an active pharmaceutical ingredient (API) in the production of INDO drugs due to its higher apparent solubility and bioavailability. The crystal state also encompasses various crystal forms such as the α-crystal form (α-INDO) and γ-crystal form (γ-INDO), with the highly crystalline and insoluble γ-INDO being commercially available. A-INDO, existing in a thermodynamically high-energy state, is susceptible to several factors during the preparation, storage, and transportation of API leading to its conversion into γ-INDO, thus impacting the bioavailability and efficacy of INDO drugs. Therefore, quantitative analysis of the A-INDO/γ-INDO content in INDO API becomes essential for controlling the production quality of INDO. The primary objective of this study is to investigate the feasibility of NIR for the quantitative analysis of A-INDO in INDO API, and to further elucidate its quantitative analysis mechanism. The NIR spectral data were collected for A-INDO and γ-INDO binary mixture samples with different resolutions, and these spectra were then selected and reconstructed using the interval partial least square (iPLS) method. Different pretreatment methods were employed to enhance the reconstructed spectra by highlighting relevant eigen information while eliminating invalid information caused by environmental factors or physical characteristics of samples. The most suitable PLSR model for quantitative analysis of A-INDO within the range of 0.0000-100.0000% w/w% was established, screened, and validated. From various perspectives, including distribution of spectral effective information, impact of resolution on PLSR model performance, variance contribution/cumulative variance contribution of PLSR model principal components (PCs), PCI loadings, relationship between spectral scores, and A-INDO content, feasibility assessment was conducted for the quantitative analysis of A-INDO in INDO using NIR spectroscopy. Additionally, a detailed investigation on the quantitative analysis mechanism of the optimal PLSR model was undertaken including the correlation between the characteristic peaks of spectra and information regarding hydrogen groups or hydrogen bonds in A-INDO or γ-INDO molecules. This study aims to provide theoretical support for the quantitative analysis of A-INDO in INDO API as well as serve as a reliable reference method for API quantification and quality control in similar drugs.

Optimization of a wideband discrete Raman amplifier in a P2O5-doped optical fiber using multi-objective grey wolf algorithm

This paper demonstrates the use of the multi-objective grey wolf algorithm to optimize a discrete Raman amplifier (DRA) in a P2O5-doped optical fiber. Specifically, the multi-objective grey wolf algorithm is combined with the DRA to carry out a process that seeks to maximize the gain and minimize the ripple. The P2O5-doped optical fiber employed in this study has a Raman gain coefficient spectrum with multiple peaks with different frequency shifts. This allows them to be combined in more complex ways than optical fibers with a single peak in the Raman gain spectrum. Consequently, the gain curve produced with this fiber has the potential to be more adjustable even when fewer pumps are used. Thus, this paper explores this fact to perform, to the best of our knowledge, the first specialized optimization process reported in the scientific literature of a wideband discrete Raman amplifier in a P2O5-doped optical fiber. With a different gain profile of this fiber compared to those of traditional standard optical fibers, it was possible to design a wideband DRA, going from 1530 nm to 1675 nm, covering C+L+U bands, maintaining a ripple of up to 8 dB with a net gain of 14 dB using only 3 pumps. Moreover, this work demonstrates for the first time, through a comparative analysis, that the multi-objective grey wolf algorithm performs better than the standard and well-known non-dominated sorting genetic optimization algorithm to optimize a DRA in a P2O5-doped optical fiber. The proposed DRA is a feasible, low-cost, and simple alternative for building fiber amplifiers for future high-bandwidth and wideband wavelength division multiplexing (WDM) communication systems, network infrastructures such as data centers, undersea cables, 5G and beyond, and cutting-edge research applications.

Indefinitely flat rotation curves from Mpc sized charged cocoons

Weak lensing exhibits that rotation curves of isolated galaxies remain flat up to Mpc scale (Mistele T. et al. Astrophys. J. Lett.9692024L3). Recently we proposed that dark matter is a combination of electrostatic and vacuum energy in standard physics. In this theory, isolated galaxies may be embedded in “charged cocoons”, spheres with charge density. The related circular rotation curves decay at the Mpc scale. The analytic solution is extended to the early Universe. A peak in the cosmic microwave background spectrum is expected at the arcsec scale. The induced nanometer size of the cocoons at the Big Bang makes the initial state inhomogeneous.

TT Arietis: New approach to the analysis of quasi-periodic oscillations

Context. TT Arietis (TT Ari) is a nova-like cataclysmic variable of the VY Scl subtype with light-curve variations on multiple timescales. In addition to the superhump modulation, quasi-periodic oscillations (QPOs) have been found. Aims. Our aim is to determine the occurrence, strength, and variability of QPOs in TT Ari based on more complete data than in previous works. Methods. The data were obtained during the high state of TT Ari in October 2012 by the MOST space telescope, covering a total of 361.2 hours of continuous observation. We searched for frequencies over subsets of time using a Fourier-like power spectrum and then added the frequencies together, forming groups. Results. Our method has revealed QPOs that occur in ‘frequency groups’, which are events with a continuous oscillation of similar, constant or slowly variable frequency. We report a total of 160 frequency groups in the period range between 14 and 53 minutes (27 and 98 days−1), with two peaks in the power spectrum at 18.5 and 33.8 minutes (42.5 and 77.5 days−1). The duration of these frequency groups varies between 0.72 and 7.5 hours (average 2.8 hours) revealing between 3 and 18 complete cycles in the light curve. Most of them show significant frequency variations over the course of their duration. Sometimes two frequency groups occur simultaneously. An analysis with randomised data confirms that stochastic processes can only explain a fraction of the QPOs found. The occurrence of QPOs appears not to be related to the superhump phase.

XPS study of pyrochlore type Bi2Cu1/3Ni1/3Co1/3M2O9±δ (M-Nb,Ta)

Mixed oxide cubic pyrochlores of the composition Bi2Cu1/3Ni1/3Co1/3(Nb/Ta)2O9±δ (sp.gr. Fd-3m) were synthesized for the first time by standard ceramic technology. According to X-ray phase analysis and Rietveld analysis, the Bi2Cu1/3Ni1/3Co1/3(Nb/Ta)2O9±δ samples are single-phase and have a cell parameter of 10.5416(3)/10.5341(2) Å, respectively. The chemical state of transition element cations in oxide pyrochlores was characterized by X-ray photoelectron spectroscopy (XPS). The Nb 3d and Ta 4f spectra of the synthesized pyrochlores exhibit a characteristic shift to lower energies by 0.65 eV, which indicates that the effective charge of the niobium and tantalum cations is +(5-δ). A shift of Bi 4f spectra by 0.25 eV is typical only for niobium pyrochlore. It has been shown that NEXAFS Cu 2p spectra of oxide ceramics, according to the main characteristics of the spectrum, represent a superposition of spectra from Cu(I) and Cu(II) cations. Based on the analysis of the relative intensity of the peaks in the XPS spectrum of Cu 2p for pyrochlores, the content of Cu(I,II) cations was estimated. The ratio of Cu(I) to Cu(II) cations in niobium pyrochlore is higher than in tantalum pyrochlore, with approximately two times more Cu(I) cations than Cu(II). X-ray spectroscopy studies indicates that Co and Ni cations are present in the valence state (II, III).