Search Results (45)

Practical development of terahertz technology requires higher power radiation sources. The sheet electron beam vacuum device is an effective solution of increasing the output power of terahertz radiation sources, but faces the difficulty of stable transmission of the beam. In this paper, a compact quadrupole permanent magnet (QPM) focusing system for terahertz sheet beam devices is designed, and a practical focusing system is constructed into a prototype for beam transmission verification. In the experiment, 16 pieces of high-performance NdFeB permanent magnets were adopted with a total weight of about 10 kg. The magnetic field test of the system was carried out and the results show that the system can provide a uniform high-intensity magnetic field of over 0.95 T within an axial length of 20 mm. With the tested QPM magnetic field configuration, PIC simulation of the sheet beam transmission was implemented, indicating that a sheet electron beam with a 20 kV voltage and 15 mA current can travel through a beam tunnel of a cross-section 0.1 mm × 0.05 mm, with a transmission ratio of 98.5%. Full article

We study the axial and polar perturbations of slowly rotating Ellis–Bronnikov wormholes in General Relativity, applying a perturbative double expansion. In particular, we derive the equations for $l=2$, $M_z=2$ perturbations of these objects, which are parametrized by an asymmetry parameter. The equations constitute an astrophysically interesting sector of the perturbations that contribute dominantly to the gravitational wave radiation. Moreover, calculation of these modes may exhibit potential instabilities in the quadrupole sector. Full article

The generation of high-quality mid-infrared free-electron laser (MIR-FEL) radiation depends critically on precise control of electron beam parameters, including energy, energy spread, transverse emittance, bunch charge, and bunch length. At the PBP-CMU Electron Linac Laboratory (PCELL), effective beam diagnostics are essential for optimizing FEL performance. However, dedicated systems for direct measurement of transverse emittance and bunch length at the undulator entrance have been lacking. This paper addresses this gap by presenting the design, simulation, and analysis of diagnostic stations for accurate characterization of these parameters. A two-quadrupole emittance measurement system was developed, enabling independent control of beam-focusing in both transverse planes. An analytical model was formulated specifically for this configuration to enhance emittance reconstruction accuracy. Systematic error analysis was conducted using ASTRA beam dynamics simulations, incorporating 3D field maps from CST Studio Suite and fully including space-charge effects. Results show that transverse emittance values as low as 0.15 mm·mrad can be measured with less than 20% error when the initial RMS beam size is under 2 mm. Additionally, quadrupole misalignment effects were quantified, showing that alignment within ±0.95 mm limits systematic errors to below 33.3%. For bunch length measurements, a transition radiation (TR) station coupled with a Michelson interferometer was designed. Spectral and interferometric simulations reveal that transverse beam size and beam splitter properties significantly affect measurement accuracy. A 6% error due to transverse size was identified, while Kapton beam splitters introduced additional systematic distortions. In contrast, a 6 mm-thick silicon beam splitter enabled accurate, correction-free measurements. The finite size of the radiator was also found to suppress low-frequency components, resulting in up to 10.6% underestimation of bunch length. This work provides a practical and comprehensive diagnostic framework that accounts for multiple error sources in both transverse emittance and bunch length measurements. These findings contribute valuable insight for the beam diagnostics community and support improved control of beam quality in MIR FEL systems. Full article

Lighthill’s theory of sound generation was developed to calculate acoustic radiation from a narrow region of turbulent flow embedded in an infinite homogeneous fluid. The theory is extended to include a simple model of non-isothermal fluid that allows finding analytical solutions. The effects of one specific temperature gradient on the wave generation and propagation are studied. It is shown that the presence of the temperature gradient in the region of wave generation leads to monopole and dipole sources of acoustic emission and that the efficiency of these two sources may be higher than Lighthill’s quadrupoles. In addition, the wave propagation far from the source is different than in Lighthill’s original work because of the presence of the acoustic cutoff frequency resulting from the temperature gradient. Full article

Background/Objectives: Saussurea obvallata (DC.) Edgew., Asteraceae, is a traditional medicinal herbnative to the Qinghai–Tibet Plateau (QTP). Pharmacological investigationshave validated its pharmacological effects in anti-tumor, anti-inflammatory, heat-clearing, detoxifying, and analgesia. S. obv is presently facing habitat fragmentation and population decline. Therefore, we analyzed its genetic and chemical diversity to provide a scientific basis for the conservation and sustainable use of S. obv. Methods: Seven populations of S. obv were sampled from Xizang, China. The genetic diversity was analyzed using inter-simple sequence repeat (ISSR) markers, and metabolites were identified by ultra-high-performance liquid chromatography-tandem-quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF-MS/MS). Correlation analysis among genetic diversity, differential metabolites, and climatic factors were performed by R. Results: The genetic diversity among and within populations were both lowly and significantly correlated with geographical distance, showing a decreasing trend from east to west of the QTP. A total of 110 compounds were identified, including flavonoids, phenylpropanoids, lipids, fatty acids, terpenoids, alkaloids, etc. The metabolite contents among populations varied greatly and were related to environmental factors, mainly annual mean temperature and temperature fluctuation. The genetic diversity had little effect on the metabolic differences. Conclusions: These findings provided valuable baseline information for the conservation and pharmacological utilization of S. obv. Meanwhile, further research is necessary for the efficacy evaluation of anti-inflammatory, anti-tumor, radiation protection, and scar removal both in vitro and in vivo. Full article

Heavy metal pollution is a major environmental concern due to the high toxicity of heavy metals in humans. High natural background radiation areas (HNBRAs) contain high concentrations of the radioactive element ²³⁸U, which decays into ²⁰⁶Pb, in their soil, crops, and water. Concentrations of the heavy metals lead (Pb) and uranium (U) are, thus, correlated with HNBRAs. Mamuju in Indonesia is a recently studied HNBRA where high concentrations of Pb and U in the soil have been reported. The present study analyzes Mamuju residents’ exposure to Pb and U. Two zones in the study area were selected for comprehensive assessment. North Botteng was chosen to represent the HNBRA, and Topoyo was selected as the control zone, with 22 urine samples collected from each zone. The samples were analyzed using a quadrupole inductively coupled plasma mass spectrometer (ICP-MS). The average concentrations of Pb measured in the urine samples were 1.31 mg L⁻¹ and 0.77 mg L⁻¹ in North Botteng and Topoyo, respectively. These values are higher than the urine Pb reference value of 5 µg L⁻¹. The urine Pb concentrations in both studied zones were alarmingly high, which may have serious health effects on the population and should warrant action to reduce Pb exposure in this area. The committed effective dose from the ingestion of ²³⁸U in North Botteng was higher than in Topoyo, measuring 36.0 mSv and 8.9 mSv, respectively. The area most affected by the ingestion of ²³⁸U was the red bone marrow, followed by the bone surface. Full article

Earlier, a significant enhancement of the nondipole parameters ${\gamma }_{2p}$, ${\delta }_{2p}$, and ${\zeta }_{2p}={\gamma }_{2p}+3{\delta }_{2p}$ in the photoelectron angular distribution for Ne $2p$ photoionization was predicted, owing to resonance interference between dipole ($E1$) and quadrupole ($E2$) transitions. This enhancement manifests as narrow resonance spikes in the parameters due to the low-energy $2s\to 3p$ and $2s\to 4p$ dipole, as well as the $2s\to 3d$ quadrupole autoionizing resonances. Given the unique nature of this predicted enhancement, it requires further validation, specifically regarding whether these narrow spikes in ${\gamma }_{2p}$, ${\delta }_{2p}$ and ${\zeta }_{2p}$ will or will not retain their values for experimental observation if one accounts for a typical finite frequency spread in the ionizing radiation. To address this, we revisit the previous study, now incorporating the effect of frequency spread in the ionizing radiation, assuming a spread as large as 5 meV at the half-maximum of the radiation’s intensity. In the present paper we demonstrate that while the frequency spread does affect the resonance enhancement of ${\gamma }_{2p}$, ${\delta }_{2p}$ and ${\zeta }_{2p}$, these parameters still retain quantitatively significant values to be observed experimentally. The corresponding calculations were performed using the random phase approximation with exchange, which accounts for interchannel coupling in both dipole and quadrupole photoionization amplitudes. Full article

This study was conducted to investigate the differences in chemical composition between red (RGBs) and yellow ginseng berries (YGBs) and their whitening and anti-aging skincare effects. The differences in the chemical composition between RGB and YGB were analyzed by ultra-high-performance liquid chromatography tandem quadrupole electrostatic field orbit trap mass spectrometry (UHPLC-Q-Exactive-MS/MS) combined with multivariate statistics. An aging model was established using UVB radiation induction, and the whitening and anti-aging effects of the two ginseng berries were verified in vitro and in vivo using cell biology (HaCaT and B16-F10 cells) and zebrafish model organisms. A total of 31 differential compounds, including saponins, flavonoids, phenolic acids, and other chemical constituents, were identified between the two groups. Superoxide dismutase (SOD) activity was more significantly increased (p < 0.05) and malondialdehyde (MDA) content was more significantly decreased (p < 0.01) in RGB more than YGB induced by UVB ultraviolet radiation. In terms of whitening effects, YGB was more effective in inhibiting the melanin content of B16-F10 cells (p < 0.01). The results of zebrafish experiments were consistent with those of in vitro experiments and cell biology experiments. The DCFH fluorescence staining results revealed that both ginseng berries were able to significantly reduce the level of reactive oxygen species (ROS) in zebrafish (p < 0.01). Comparison of chemical composition and skin care activities based on RGB and YGB can provide a theoretical basis for the deep development and utilization of ginseng berry resources. Full article

The present investigation was performed to figure out the chemical constituents and biological potential of polar extracts (AcOEt and BuOH) from Achillea ligustica, a medicinal species of the Asteraceae family. Liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS) was utilized to conduct a preliminary analysis of the phytochemical profiles of the AcOEt and BuOH extracts. The analysis revealed the existence of twenty compounds in the AcOEt extract and twenty-two in the BuOH extract, classified into various types of secondary metabolites. Subsequently, the exudate from the plant yielded five flavonoids, including two 6-methoxyflavonols identified for the first time in this genus. The isolation of compounds from AcOEt and BuOH extracts was achieved through the combined use of column chromatography (silica gel and Sephadex LH-20) and preparative TLC chromatography. The structures have been elucidated using 1D and 2D NMR spectroscopy, alongside comparisons with research data. Our study measured the total phenolic and flavonoid contents and carried out a comprehensive range of antioxidant tests using DPPH, GOR, CUPRAC, reducing power, and O-phenanthroline assays. Both extracts exhibited considerable antioxidant potential and contained high levels of phenolic and flavonoid compounds. The photoprotective effect of the AcOEt and BuOH extracts was evaluated in vitro by measuring the sun protection factor. Both extracts exhibited a high capacity for UV radiation absorption. Consequently, this plant presents an intriguing prospect for future research focused on incorporating it into photoprotective cosmetic products and pharmaceutical formulations. Full article

In this paper, we demonstrate the interaction of 674 nm laser radiation with a clock quadrupole transition in high-energy ⁸⁸Sr⁺ ions obtained by laser ablation. The results of the spectrometry of the clock and the pump transitions are presented. We describe the parameters of the experimental setup and the protocol of the clock transition spectroscopy and analyze various line broadening mechanisms. Full article

Ionizing radiation exposure is known to induce molecular and cellular injury, inflicting a cascade of potentially catastrophic events leading to tissue and organ damage. Metabolomic analysis allows for the identification and quantification of small molecules downstream of genomic changes induced by radiation exposure. We aimed to characterize metabolomic changes that underscore the prefinal stage of lethally irradiated rhesus nonhuman primates (NHPs). Peripheral blood was drawn at baseline, post-exposure, as well as at the preterminal stage in NHPs (immediately prior to death in moribund NHPs) that did not survive exposure with 7.2 Gy total-body radiation (LD_70/60). Herein, we analyzed global metabolomic changes using ultra-performance liquid chromatography (UPLC) quadrupole time-of-flight mass spectrometry (QTOF-MS) in plasma samples of NHPs collected at various timepoints in relation to irradiation. The overall goal was to identify metabolic shifts present immediately prior to death. Our findings showed radiation induced significant time-dependent metabolic perturbations when compared to pre-irradiation profiles, particularly in glycerophospholipid metabolism and steroid hormone biosynthesis and metabolism pathways. These findings provide valuable insights for identifying biomarkers for lethality, which may be helpful for triage during a mass casualty scenario. Full article

Mamuju is an area of high natural radiation in Indonesia with high natural radiation levels (average 613 nSv h⁻¹). Mamuju is anomalous due to its high average ²³⁸U and ²³²Th concentrations of 22,882 and 33,549 Bq kg⁻¹, respectively, in laterite and rock. High natural radionuclide concentrations of ²³⁸U, ²³²Th, and ⁴⁰K have also been reported in soil samples from several locations in Mamuju, including Botteng, Northern Botteng, Takandeang, Ahu, and Taan. High radiation levels are related to radioactive mineral occurrences in the Adang volcanic complex, comprised of phonolitoid and foiditoid lithologies. According to the International Atomic Energy Agency (IAEA), uranium deposits can be classified into several types, among them a volcanic-related deposits, which include three sub-types: stratabound, structure-bound, and volcano-sedimentary deposits. This study aims to characterize volcanic rock deposit sub-types in the Mamuju area based on uranium radioisotope measurements. The uranium isotopes were measured using a tandem quadrupole inductively coupled plasma mass spectrometer combined with chemical separation by extraction chromatography using UTEVA resin. The analytical results for the ²³⁴U/²³⁸U ratios are used to determine the formation characteristics of minerals in each deposit sub-type based on mineral formation age, post-formation processes, and disturbances that affected the formation processes. Based on geochronological calculations using ²³⁴U/²³⁸U mineralization age, the deposits in the Mamuju area are 0.914–1.11 million years old and are classified as recent mineralization. These data have important implications for tracing uranium source rocks in the Mamuju area and may explain the anomalously high radiation levels in the Mamuju area. Full article

This article considers the possibility of using a magnetron-deposited coating for the protection of hafnium hydrides at high temperatures as a material for neutron control rods. We describe the role of TiC coating in the high-temperature behavior of hafnium hydrides in a vacuum. A 1 µm thick TiC coating was deposited through magnetron sputtering on the outer surface of disk HfH_x samples, and then in situ X-ray diffraction (XRD) measurements of both the uncoated and TiC-coated HfH_x samples were performed using synchrotron radiation (at a wavelength of 1.64 Å) during linear heating, the isothermal stage (700 and 900 °C), and cooling to room temperature. Quadrupole mass spectrometry was used to identify the hydrogen release from the uncoated and TiC-coated hafnium hydride samples during their heating. We found the decomposition of the HfH_1.7 phase to HfH_1.5 and Hf and following hafnium oxidation after the significant decrease in hydrogen flow in the uncoated HfH_x samples. The TiC coating can be used as a protective layer for HfH_x under certain conditions (up to 700 °C); however, the fast hydrogen release can occur in the case of a coating failure. This study shows the temperature range for the possible application of TiC coatings for the protection of hafnium hydride from hydrogen release. Full article

The noise radiated by the flow around a cylinder in the subcritical regime at $R{e}_D=1\times {10}^4$ and at a subsonic Mach number of $M=0.5$ is here studied. The aerodynamic sound radiated by a cylinder has been studied with a wide range of Reynolds numbers, but there are no studies about how the Mach number affects the acoustic field in the subsonic regime. The flow field is resolved by means of large-eddy simulations of the compressible Navier–Stokes equations. For the study of the noise propagation, formulation 1C of the Ffowcs Williams–Hawkings analogy is used. The fluid flow results show good agreement when comparing the surface pressure coefficient, the recirculation length, the vortex shedding frequency and the force coefficients against other studies performed under similar conditions. The dynamic mode decomposition of the pressure fluctuations is used to relate them with the far-field noise. It is shown that, in contrast to what happens for low Mach numbers, quadrupoles have a significant impact mainly in the observers located in the streamwise direction. This effect leads to a global monopole directivity pattern as the shear fluctuations compensate for the lower value of the aeolian tone away from the cross-stream direction. Full article

Propulsion noise is an enduring problem of significant military and environmental importance. Hence, it is crucial to investigate propeller noise characteristics. In this study, the hydrodynamic performance and noise level of the DARPA (Defense Advanced Research Projects Agency) Suboff submarine with the E1619 propeller were analyzed. The hull resistance and propeller hydrodynamics were studied separately, and the numerical results were validated using available experimental values. The self-propulsion point was determined by matching the hull resistance and propeller thrust following ITTC (International Towing Tank Conference) convention. Based on hydrodynamics and acoustic Ffowcs Williams–Hawkings (FW–H) models, the underwater-radiated noise characteristics in the self-propulsion state were simulated. The calculations indicated that the contribution of the quadrupole term in the FW–H equation is not negligible in the high-frequency band. Compared with the noise of open-water propellers, the spectrum of the E1619 propeller in its self-propulsion state is more complex, and the upstream noise is amplified. Full article