Accurate measurement of the activity of medical radioactive isotopes is crucial for ensuring the safety of diagnosis and treatment as well as patient therapeutic efficacy. A calorimeter is designed to measure the decay heat generated by medical radioisotopes in microwatt precision, based on the thermopile heat-flow sensors used for twin cylinder chambers. The simulation reveals that the equilibrium temperature distribution inside of the calorimeter can be precisely controlled by the water bath and the automatic thermostatic control components. The experimental results show that the temperature control accuracy can reach +/- 0.0005 degrees C under the proportional-integral-derivative regulation. The output thermoelectric potential shows a significant linear relationship with the input thermal power, achieving a sensitivity coefficient of 0.297 V/W during the electrical power calibration of the calorimeter. The lowest detectable thermal power is 1.6 mu W in the steady-state equilibrium mode with the baseline correction. The minimum time to establish thermal equilibrium is about 15 min for microwatt power, and approximately 30 min for milliwatt power, respectively.

Diamond-like carbon (DLC) is an ideal protective material for sliding parts in hydrocarbon environments (e.g., CH4) due to its high hardness, low friction, and excellent chemical inertness. However, active hydrogen radicals generated during friction can induce structural degradation and transfer film instability. Noble metal doping, e.g. Ag, effectively optimizes DLC performance. This study fabricated Ag-doped DLC (Ag-DLC) films to investigate their tribological mechanisms in a CH4 atmosphere. Results showed that increasing Ag target current promoted graphitization and Ag phase precipitation during sliding, which significantly altered the interfacial structure. Compared with the undoped film, at 0.3A, synergistic graphitization and surface passivation reduced the wear rate by nearly an order of magnitude. After the long-term sliding test, the Ag-Ag adhesion in the interfacial structure enhanced; although the friction coefficient increased slightly, the film still maintained excellent wear resistance. Excessive Ag (>0.4A) degraded mechanical properties and increased ploughing, which impaired tribological performance. The study clarifies the tribological mechanism of Ag-DLC in methane environments, supporting its application in natural gas equipment.

This work reports a novel multifunctional integrated experimental setup designed for investigating low-energy ion-surface interactions. The system incorporates multiple techniques, including dual-detector time-of-flight energy loss spectroscopy, time-of-flight mass spectroscopy, and position-sensitive charge-state spectroscopy, enabling in-situ investigation of energy loss of particles, surface analysis and charge exchange of particles in the ultra-high vacuum condition. The design of the setup and the related examples are well discussed in this work. By overcoming the limitations of traditional isolated measurement approaches, this integrated setup provides an efficient and reliable experimental platform for in-depth exploration of multiple physical processes in ion-surface interactions.

Superlubricity stands as a fundamental objective in tribology, offering considerable promise for minimizing energy dissipation and prolonging the service life of mechanical systems . This study explores the tribological behavior of S,W-incorporated hydrogenated amorphous carbon (a-C:H(S,W)) films synthesized via closed-field unbalanced magnetron sputtering. The tribological performance of films was evaluated in dry nitrogen to mimic a dry gas seal environment. The a-C:H(S,W) films demonstrate superior superlubricity (COF = 0.005) with an 84 % reduction in wear rate compared to a-C:H films, primarily attributed to microstructural modifications induced by trace sulfur incorporation. The results reveal that sulfur incorporation facilitates the formation of ordered carbon networks through promoted sp2-C clusters in a-C:H(S,W) films. This sulfur-mediated structural evolution simultaneously enhances the stability of graphite-like tribolayer at friction interfaces, significantly improving wear resistance. During the friction process, hydrogenation induces the development of a unique sp(2)-C/sp(3)-C interfacial architecture, where the synergistic combination of this incommensurate contact and hydrogen-saturated weak-shear interfaces collectively enables macroscopic superlubricity. This understanding bridges atomic-level bonding characteristics (C-S coordination and sp(2)-C clustering) with macroscopic tribological performance, demonstrating sulfur incorporation as an effective strategy for designing durable superlubricious carbon films. (c) 2026 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

We investigated the energy transfer upon collision between CO and various noble gases (He, Ne, and Ar) using stimulated Raman scattering (SRS) to excite CO X1Σ+(0, 7) to vibrational excited states CO X1Σ+(v = 2, 3, 4, J = 8). CO was confirmed to be excited to v = 2, 3, 4 using coherent anti-Stokes Raman spectroscopy (CARS). A semi-logarithmic plot of time-resolved CARS spectra was used to determine the effective lifetimes τ of CO. The τ of excited-state CO steadily decreases with increasing gas molar ratio, according to a comparison of the CO-He, CO-Ne, and CO-Ar systems; however, there is no significant correlation between the τ of excited-state CO and its energy level. By studying the effective lifetime of excited-state CO in the system at different temperatures, it was found that the effective lifetime gradually decreases with increasing temperature. Using the Stern–Volmer equation in conjunction with the relationship between the effective lifetime of CO and α, the collision energy transfer rate coefficients for CO in different noble gas systems at various excitation energies were obtained. It was found that the collision energy transfer rate coefficients gradually decrease as the atomic mass of the noble gas increases. However, for the same noble gas system, the rate coefficient for CO collision energy transfer does not vary significantly with excitation energy. The effect of temperature on the transfer rate was also investigated, and it was found that the collision energy transfer rate is positively correlated with temperature.

Constructing lightweight, outstanding electromagnetic wave absorbers through simple methods represents one of the key strategies to tackle electromagnetic pollution. Here, Fe2O3-modified carbon nanotube/cellulose composite (FCCA) was prepared by freeze-drying with cellulose nanofiber (CNF) as the matrix and the Fe2O3 nanoparticles and carbon nanotube (CNT) as functional fillers. The results indicate that the FCCA composite effectively attenuates electromagnetic waves by extending their propagation path to enhance multi-reflection and scattering, while the introduced CNT impart excellent conductivity, leading to substantial conduction loss. Also, the weakly magnetic Fe2O3 nanoparticles optimizes impedance matching, offers permeability, and enriches the electromagnetic wave dissipation mechanisms. Meanwhile, the abundant heterogeneous interfaces in the FCCA composite generate significant interface polarization, enhancing the polarization relaxation loss of electromagnetic waves. With an Fe2O3 nanoparticle loading of 20% (Fe2O3:CNT=20%), the FCCA-20 composite demonstrated a competitive density of 48.1 mg cm-3. When the thickness was 2 mm, it delivered excellent absorption performance, characterized by a RLmin of -63.5 dB alongside a favorable bandwidth of 5.02 GHz. Furthermore, simulation of the RCS confirmed a maximum reduction of 24.22 dB m2, which indicates effective electromagnetic wave attenuation by the FCCA composite.

This study investigates the adsorption of alkali-metal atoms (Li, Na, and K) on one-to-four-layer graphene using first-principles calculations, with relevance to ion batteries and energy storage applications. The adsorption energy, electronic structure, and charge transfer are found to depend on the number of graphene layers. The shift in the Fermi level from the Dirac point decreases with increasing layer number, and the density of states at the Dirac point becomes non-zero beyond two layers. Differential charge density and Bader charge analyses reveal that electrons are predominantly transferred from the adatoms to the top graphene layer, inducing interlayer polarization. The amount of charge transfer increases with the number of layers, though the trend saturates beyond three layers. These fundamental insights into thickness-dependent alkali-metal-graphene interactions may provide a basis for understanding potential applications in ion batteries and energy storage, though practical considerations such as coverage effects and diffusion barriers require further study.

The efficient neutralization of alkali-metal ions on high-work-function metal surfaces at low incident energies has not been understood well at present. To study this mechanism, we measured the neutral fraction of Na+ ions scattering on the high-work-function Pd(111) and Au(111) surfaces at the 7o scattering angle in the energy range of 0.2-5 keV. The non-monotonic exit-angle dependent neutral fraction for 0.3 keV Na+ ions has been obtained. The neutral fractions sharply decrease to about zero with the increase of incident energy, which is different from our previous work at large scattering angle. It indicates that the scattering angle has a great influence to the neutralization. The calculations show that the neutral atoms which efficiently formed at short ion-surface distances spend more time at large distances when departing from the surface at the grazing scattering angle and lose the electron to finally become positive ions, which qualitatively explains the less neutral fraction observed experimentally.

We present a Faraday Cup Array (FCA) beam profile monitor designed for rapid monitoring of high-intensity direct current ion beams. The monitor consists of 2112 small Faraday cups (FCs) arranged uniformly in a grid pattern over an area of 89.2 × 89.2 mm2. These FCs are arranged in rows and columns, forming 64 independent channels, which are evenly split into 32 x-channels and 32 y-channels, with each channel comprising 33 FCs. Each channel is connected to an independent channel of a 64-channel picoammeter, allowing all channels to conduct current measurements simultaneously and independently. The monitor is capable of directly detecting the projections of beam current distribution in both horizontal and vertical directions with a spatial resolution of 2.75 mm within 1 s. We tested it using He2+ beams with energies of 120 and 200 keV, corresponding to beam powers of 15 and 27.5 W, respectively. The temperature increases on its front and back sides were monitored during the test. We also studied the thermal conduction and temperature rise through simulations when it was exposed to ion beams.

The resonant charge transfer process based on the jellium model of free electron gas is normally used to explain the neutralization of alkali-metal ions scattering on metal surfaces with low work functions. However, we find it cannot adequately account for the angle dependent neutralization of keV-energy Na+ ions in grazing scattering on Al(100) and Al(110) surfaces. The bell shape of the angle dependent neutralization is observed for Al(110) in contrast to the opposite shape for Al(100). In particular, Na2+ ions are observed at the rough Al(100) surface, which provides direct evidence of electron excitation in Na-Al collisions. The neutralization of the non-specular scattering for Na-Al systems is dominated by the combination of the resonant charge transfer and the electron promotion mechanisms.

Measurements of the crystal azimuthal angle-dependent energy losses have been performed by means of a time-of-flight method for 3-keV negative fluorine ions in grazing scattering on a missing row reconstructed Au(110) surface. The energy-loss spectra exhibit the single-peak structure in the vicinity of the azimuthal angle of 0 degrees. As the azimuthal angle increases from 0 degrees to 6.12 degrees, the spectra broaden at certain angles, with a slight shoulder emerging and subsequently disappearing, accompanied by fluctuations in the peak position. An obvious double-peaked structure is observed near the azimuthal angle of 70.5 degrees. With the azimuthal angle decreasing, high energy-loss peak gradually diminishes, while the low energy-loss peak persists. The energy-loss spectra are discussed in terms of the trajectory simulations by Kalypso code. The spectra features are primarily determined by the relative contributions of two distinct classes of trajectories.

Dust activity is highly sensitive to changes in Earth's surface systems in arid regions and plays a critical role in regulating global climate dynamics and biogeochemical cycles. Central Asia is a key region of atmospheric dust emissions, yet the absence of high-resolution late Holocene records limits our understanding of centennial-scale dust variability and its drivers. This study provides a centennial-scale reconstruction of dust activity in the central Tien Shan during the late Holocene using a sedimentary archive from Xiannv Lake. The lake offers an exceptional record based on multi-proxy analyses of core-scanning XRF, grain size, and high-resolution pollen assemblages. Peaks in titanium (Ti) concentrations, coupled with increased silt content, reduced pollen concentrations, and a low Artemisia/Chenopodiaceae (A/C) ratio indicate episodic dust deposition from low-altitude desert sources. At least seven distinct dust events were identified at approximately 2.6 ka, 1.75 ka, 1.6 ka, 1.1 ka, 0.9 ka, 0.4 ka, and 0.25 ka, each with varying durations. We show that these events coincide with key atmospheric circulation shifts, suggesting that intensified dust activity in arid Central Asia was mainly driven by the strengthening of the Siberian High and the weakening of westerlies modulated by the North Atlantic Oscillation. A prolonged drought and dust episode recorded in both Xiannv and Bosten Lakes aligns with regional societal disruption, likely contributed to the collapse of the Loulan Kingdom. These findings underscore the interplay between atmospheric dynamics, environmental stress, and societal vulnerability during the late Holocene climate extremes in Central Aisa.

In this work, we present a comparative experimental study of energy losses of 2-4 keV hydrogen and helium ions in grazing scattering on an Au(111) surface. We performed energy loss measurements as a function of the crystal azimuthal angle and the incident energy by means of a time-of-flight method with a pulsed beam. The most probable energy losses increase monotonously with increasing incident velocity for H+ and He+ incident ions. As the incident energy increases, the energy-loss spectra exhibit a broader shape and the tail becomes longer along the 0 degrees and 30 degrees azimuthal angles. In particular, the most probable energy losses vary around the azimuthal angle of 30 degrees for 4 keV H+ ions while they are not observed for 3 keV H+ ions. It also does not change around the 0 degrees azimuthal angle for H+ and He+ incident ions. The energy loss spectra for hydrogen ions exhibit a broader shape than for helium ions at some azimuthal angles. The experimental results strongly depend on crystal azimuthal orientations, which reveal a pronounced surface effect.

When the space high-energy electron storm is generated in the Space Solar Power Station, the high voltage biased on the dielectric materials is a key factor affecting the deep charging process. In this work, the electron transport process in poly-ether-ether-ketone flat plates has been studied by the Geant4 simulation. It is found that the trapped charge density enhances 2-3 orders of magnitude under high-energy electron storms and that the trapped charge density gradually increases with the increase of the radiation time. The number of electrons deposited and charge migration decreases as the shielding thickness increases, while the trapped charge density decreases significantly and its spatial distribution gradually changes to a concave distribution.

The adsorption and reactions of water with surfaces is of immense importance in catalysis and corrosion. Charge transfer of ion scattering is sensitive to changes of work function and electronic structure caused by adsorption of water on a surface. In this work, as the model systems of metals and semiconductors the water adsorbed copper and silicon surfaces have been chosen and the research progress of charge transfer of the negative and positive ion scattering in our group were reviewed.

Reconstructing Holocene temperature evolution is important for understanding present temperature variations and for predicting future climate change, in the context of global warming. The evolution of Holocene global temperature remains disputed, due to differences between proxy reconstructions and model simulations, a discrepancy known as the ‘Holocene temperature conundrum’. More reliable and quantitative terrestrial temperature records are needed to resolve the spatial heterogeneity of existing records. In this study, based on the analysis of branched glycerol dialkyl glycerol tetraethers (brGDGTs) from a loess-paleosol sequence from the Ganjia Basin in the north-eastern Tibetan Plateau (NETP), we quantitatively reconstructed the mean annual air temperature (MAAT) over the past 12 ka. The MAAT reconstruction shows that the temperature remained low during the early Holocene (12–8 ka), followed by a rapid warming at around 8 ka. From 8 to 4 ka, the MAAT record reached its highest level, followed by a cooling trend from the late Holocene (4–0 ka). The variability of the reconstructed MAAT is consistent with trends of annual temperature records from the Tibetan Plateau (TP) during the Holocene. We attribute the relatively low temperatures during the early Holocene to the existence of ice sheets at high-latitude regions in the Northern Hemisphere and the weaker annual mean insolation at 35°N. During the mid to late Holocene, the long-term cooling trend in the annual temperature record was primarily driven by declining summer insolation. This study provides key geological evidence for clarifying Holocene temperature change in the TP.

Luminescence defects, which are commonly known as color centers in hexagonal boron nitride (hBN), are promising for applications in quantum sensing and emitters, but most of them are challenging to efficiently fabricate and identify. Here, we explore the photoluminescence (PL) spectra of color centers in hBN-based heterojunctions. We clearly observed a series of PL spectra with peaks at similar to 680 nm in monolayer and nanometer-thick hBN/SiO2 heterojunctions after helium-ion irradiation; the line shape and line width of those PL spectra are the same as the boron vacancy in bulk hBN with a peak at 818 nm. We also demonstrated a generation strategy for a carbon-related color center with a zero phonon line at 580.7 nm in a graphene/hBN/SiO2 heterojunction using 1 keV argon-ion implantation without subsequent annealing. Furthermore, density functional theory calculations were used to speculate on the atomic structures and substrate effects of color centers in hBN-based heterojunctions. This work provides a highly efficient fabrication method for carbon-related color centers in monolayer hBN as quantum emitters and finds that the color centers with peaks at similar to 680 nm in monolayer hBN are useful for the monitoring of the ion beam.

Perovskite solar cells are emerging as one of the most promising energy sources for space applications. However, the displacement damage of solar cells in the space environment has gradually deteriorated their performance. In this work, the depth distribution of primary knocked-on atoms (PKA), non-ionizing energy loss and defect concentration of CsPbI3-based perovskite solar cells irradiated by 0.1-2000 MeV protons have been simulated by the Geant4 toolkit. It is found that the PKA yield shows an obvious step behavior near the layer boundary of the solar cell, and that the electron and hole transport layers have the high defect concentration whereas the CsPbI3-based perovskite layer owns the least PKA yield. In particular, in the geostationary orbit, the radiation damage effect caused by space protons to the solar cells is approximately equivalent to that irradiated by 0.18 MeV protons, which provides a good reference for ground irradiation experiments for CsPbI3-based perovskite solar cells.

CsPbBr3 perovskite quantum dots (PQDs) are promising candidates for scintillator materials due to their tunable emission wavelength, high light yield, high atomic number, and low cost. However, their poor environmental stability hinders further practical applications. Herein, CsPbBr3 PQD thin film scintillators are encapsulated with selected PMMA, PS, and ER with different thicknesses using the spin-coating method. Photoluminescence spectroscopy is employed to evaluate the light output affected by environmental stability. The results indicated that the PS film outperforms the other two encapsulants in the thermal stability tests at 100 degrees C and humidity stability tests at relative humidity levels of 95-100%. In particular, the thick PS film, measuring 34.49 mu m, demonstrates excellent environmental stability, while the thicknesses of the films ranging from 1.44 to 34.5 mu m do not influence the light output of the CsPbBr3 PQD thin-film scintillators, a finding that is corroborated by simulations. This work has significant implications for the practical application of all-inorganic perovskite scintillators in ionizing radiation detection.