Search Results (454)

The paper presents the results of a study on the structure and electrical properties of graphite-like amorphous carbon films deposited by electron-beam evaporation with vacuum heat treatment. The current–voltage characteristics of the films were analyzed in weak and strong electric fields in the temperature range from 25 to 155 °C. For the contact of carbon films with nickel, the Schottky barrier height was calculated based on the obtained current–voltage characteristics. It was found that in the temperature range of 25–45 °C, the mechanism of direct tunneling of charge carriers through the narrow Schottky barrier dominates (φ_b = 0.055 eV). In the range of 55–75 °C, a transition to the thermally assisted tunneling mechanism is observed (φ_b = 0.076 eV). At temperatures above 85 °C, charge carrier transport through the Schottky barrier occurs via thermionic emission (φ_b = 0.3 eV). The analysis of the current–voltage characteristics of graphite-like carbon films allowed us to establish the main mechanisms of hopping conductivity via localized states. It is shown that in the temperature range of 298–348 K, conductivity is determined by states near the Fermi level. The temperature interval of 348–428 K corresponds to conductivity through the band tail of localized states near the conduction band. It is shown that the increase in conductivity in strong electric fields is due to the Poole–Frenkel effect. Full article

This work investigates the semiclassical evolution of the Hawking atmosphere surrounding evaporating, spherically symmetric anti-de Sitter (adS) black holes. We model the evaporation process within a dynamical framework, treating the emission of Hawking radiation as a quantum tunneling process through the black-hole horizon. Using the Parikh–Wilczek tunneling method, we incorporate backreaction effects, with the emission probability being linked to the resulting change in the Bekenstein–Hawking entropy of the black hole. This probability is then used to compute the time-dependent luminosity of the system, revealing significant deviations from ideal blackbody behavior, particularly for small adS black holes. For these objects, the luminosity does not increase with temperature due to strong mass variations during evaporation. To complement this microscopic approach, we compute the renormalized energy–momentum tensor for a quantum field propagating in the Vaidya-adS geometry modelling the evaporation process. Together, these approaches clarify the interplay between geometry, quantum fields, and thermodynamics in shaping the Hawking atmosphere and the evaporation dynamics of black holes in asymptotically adS spacetimes. Full article

The reaction dynamics of weakly-bound nuclear systems at near-barrier energies is a compelling topic in nuclear physics. This review summarizes decades of experimental work by the Nuclear Reaction Group at the China Institute of Atomic Energy. Using transfer reactions with the distorted wave born approximation and asymptotic normalization coefficient analyses, we confirm the first excited neutron halo (¹³C) on the $\beta$-stability line and identified new halo states in ¹²B. Total reaction cross-section measurements revealed proton halo nuclei ${}^{27}\mathrm{P}$ and ${}^{29}\mathrm{S}$, with core enlargement observed in ${}^{27}\mathrm{P}$ and ${}^{28}\mathrm{P}$. We established conditions for halo formation and delineated the proton halo existence region. In two-proton emission studies, we observed ${}^2\mathrm{He}$ cluster emission from highly excited ${}^{17,18}\mathrm{Ne}$ and ${}^{28,29}\mathrm{S}$, with ${}^{29}\mathrm{S}$ being the second such case internationally. In $\beta$-delayed decay, we discovered $\beta$2p emission in ${}^{22}\mathrm{Si}$ and determined its mass, observing isospin-symmetry breaking in ${}^{20}\mathrm{Mg}$, ${}^{22}\mathrm{Si}$, and ${}^{27}\mathrm{S}$. Decay schemes for ${}^{27}\mathrm{S}$ and ${}^{26}\mathrm{P}$ addressed the ${}^{26}\mathrm{Al}$ abundance problem. For nuclear interactions, we investigated the ${}^6\mathrm{He}$ optical potential, finding the dispersion relation inapplicable for ${}^6\mathrm{He}$ + ${}^{209}\mathrm{Bi}$, and developed notch and Bayesian methods to constrain uncertainties. For unstable nuclei, the proton drip-line systems ⁸B and ¹⁷F have been intensively studied via complete kinematics measurements of the ⁸B + ¹²⁰Sn and ¹⁷F + ⁵⁸Ni reactions, respectively. The results show that elastic breakup dominates for proton-halo ${}^8\mathrm{B}$, while inelastic breakup prevails for ${}^{17}\mathrm{F}$, with proton-rich nuclei exhibiting lower breakup probabilities than neutron-halo nuclei due to Coulomb effects. Fusion studies revealed sub-barrier enhancement in ${}^{17}\mathrm{F}$ + ${}^{58}\mathrm{Ni}$ from continuum couplings. We propose direct fusion–evaporation measurements with deflection systems integrated with breakup detection to disentangle complete and incomplete fusion channels. Full article

Advanced Doppler-shift methods for the calculation of the γ-ray lineshape registered in recoil-distance Doppler-shift and Doppler-shift attenuation methods are presented, emphasizing the case using a gate set on the shifted part of a direct feeding transition. For the precise description of the γ-ray lineshape, the process of evaporation of light particles from the compound nucleus has to be taken into account in the case of heavy ion-induced fusion-evaporation reactions. In addition, the impact of different approaches for calculating stopping powers is investigated in the process of the lifetime determinations. In the RDDS experiments, the γ-emission during the slowing down in the stopper is discussed in detail. Applications of the new procedures are demonstrated in two experiments: the first one is a plunger experiment performed in order to check for chirality in the ¹³⁴Pr nucleus and the second one is a DSAM experiment conducted to test the isospin symmetry in ³¹P and ³¹S mirror nuclei. Full article

As critical conduits for pollutant enrichment and transformation, lake inlets govern the biogeochemical cycling of emerging contaminants. This study investigated the occurrence, spatiotemporal heterogeneity, and source–sink dynamics of 15 organophosphate esters (OPEs) in the major inflowing rivers of Poyang Lake, China. Using UPLC–MS/MS, positive matrix factorization (PMF), and risk quotient (RQ) modeling, we identified the mechanisms driving pollutant distribution across three hydrological periods. Alkyl-OPEs (58.19%) and chlorinated OPEs (40.42%) dominated the contaminant burden, with TCPP and TEP identified as the primary congeners. Concentrations exhibited a distinct seasonal gradient, with higher levels during the dry season and lower levels during the wet season, controlled by seasonal hydrological dilution versus evaporative and stagnant accumulation. PMF indicated that source contributions shifted with hydrology: intense wet-season precipitation flushed non-point sources from waste and electronic products (45.1%), while reduced dry-season flow concentrated mixed inputs from agricultural runoff and ship traffic (50.7%). Ecological risk assessment identified EHDPP, TCrP, and TCPP as high-risk contaminants (RQ ≥ 1.0), posing direct threats to aquatic population. These findings highlight the need for adaptive, season-specific management of emerging contaminants at the river–lake interface, specifically by implementing enhanced interception of surface runoff during the wet season and enforcing stringent regulations on localized shipping emissions during the dry season to protect freshwater ecosystems. Full article

Rising temperatures and increasing evaporative demand accelerate soil moisture loss (SML) during the sowing-to-emergence phase of cotton (Gossypium hirsutum L.), constraining crop establishment under water-limited Mediterranean conditions. Conventional tillage (CT) involves intensive tillage operations with higher fuel and energy requirements, whereas strip tillage (ST) limits tillage to the crop row while preserving inter-row residues. This study evaluated ST and CT across two consecutive growing seasons (2024 and 2025) under a wheat–cotton rotation system. A field experiment was conducted using a replicated design (n = 8), in which emergence parameters, SML (0–10 cm), yield, and fuel-derived energy use and CO₂ emissions were quantified. SML was significantly lower under ST than CT (43% in 2024 and 52% in 2025; p < 0.001), leading to earlier emergence (0.98–1.17 days) and higher emergence rate index (ERI) values. Cotton yield was slightly higher under CT (3–4%); however, this difference, although statistically significant (p = 0.001), remained limited and consistent across years. In contrast, ST resulted in a 66–69% reduction in operational fuel use, with proportional reductions in energy use and CO₂ emissions on an area basis. Yield-scaled indicators, defined as energy use (MJ kg⁻¹) and CO₂ emissions (kg CO₂ kg⁻¹) per unit yield, further revealed substantially greater resource-use efficiency under ST compared with CT. These findings demonstrate that strip tillage enhances hydrothermal conditions during crop establishment while markedly reducing energy demand and carbon intensity, providing a resource-efficient mechanization strategy for cotton production under increasing climatic stress. Full article

The increasing need to reduce reliance on fossil-derived aviation fuels and mitigate environmental impacts has intensified research into renewable alternatives for aviation energy systems. The growing interest in ethanol-based fuels is primarily driven by their simple oxygen-rich molecular structure and advantageous physicochemical characteristics, yet experimental studies examining their application in hybrid power architectures, including micro-turboprop engine-based power sources, are still limited. This study presents an experimental investigation of ethanol–Jet A1 fuel blends used in a micro-turboprop engine operating as a power generation unit for unmanned aerial vehicle applications. Ethanol was blended with Jet A1 at volumetric fractions of 10%, 20% and 30% and the engine was tested under multiple operating regimes corresponding to different electrical power outputs. Exhaust gas temperature, electrical power output and gaseous emissions (CO and NO_x) were measured for each operating condition. The results indicate that low ethanol fractions (E10) provide performance comparable to neat kerosene, while higher ethanol fractions lead to a reduction in exhaust gas temperature at low-power regimes due to the lower heating value and high latent heat of vaporization of ethanol. Emission measurements showed a decrease in NO_x emissions with increasing ethanol content, associated with lower combustion temperatures, while CO emissions increased at low-power regimes due to incomplete combustion under lean conditions. Additionally, combustion instability was observed during rapid transitions from maximum to idle regime operation for higher ethanol blends, attributed to transient ultra-lean mixtures, evaporative cooling, and reduced reaction rates. The results demonstrate that ethanol–kerosene blends can be used in micro-turboprop systems at low blend ratios without major performance penalties, but transient operating conditions impose stability limits that must be considered in practical UAV power system applications. Full article

Sub-15 nm line structures are key building blocks for advanced device prototyping, nanoscale electrodes, and lithography templates such as etch/deposition masks. Although ultrahigh-voltage (≥100 kV) electron-beam lithography (EBL) can more readily achieve extremely small critical dimensions, its tool and infrastructure requirements limit widespread adoption in many laboratories. In contrast, 30 kV field-emission SEM platforms are far more accessible; however, resolution-limit patterning at 30 kV is more sensitive to beam current, exposure dose, and development conditions, motivating the establishment of a reproducible process flow and a well-defined process window. Here, we investigate the resolution limit of isolated lines using a Zeiss Gemini 460 system operated at 30 kV and an in-house pattern generator with 950 k PMMA C2 resist. To demonstrate device-level applicability, we develop a stable lift-off process, and all critical dimensions are evaluated on metal lines after e-beam evaporation and lift-off. By screening beam current and scanning dose to build the dose-to-size relationship, we show that reducing beam current significantly improves the achievable minimum line width. Under 35 pA, using CD ≤ 15 nm as the criterion for sub-15 nm window extraction, the usable dose range is [700, 804.3] µC/cm², corresponding to a dose latitude of ~14.9%. The best performance is obtained at 700 µC/cm², yielding a transferred metal line width of 13.85 nm after lift-off. This work provides a practical resolution-limit process flow and a quantitative process window for performing sub-15 nm patterning on accessible 30 kV platforms, supported by product-level lift-off validation. Full article

To investigate how the content of silica fume (SF) influences the performance of foam concrete (FC) after high-temperature exposure and the underlying mechanisms, this study prepared standard FC cube specimens with SF contents of 0%, 0.15%, 0.2%, 0.25%, and 0.3%. The working properties of the material at room temperature were systematically tested, and the mass loss, residual compressive strength, failure mode, microstructure and acoustic emission (AE) data at different temperatures (100 °C, 200 °C, 300 °C and 400 °C) were analyzed. The test results indicate that increasing the SF content reduces the fluidity of the fresh paste yet significantly enhances the compressive strength and lowers the water absorption of FC at room temperature. After high-temperature exposure, the effect of SF exhibits a dual character: at 200 °C and below, SF effectively mitigates the performance degradation of FC. However, when the temperature reaches 300–400 °C, specimens with an excessively high SF content (e.g., 0.3%) experience rapidly built-up internal steam pressure that cannot escape in time, which triggers the formation and propagation of a microcrack network and leads to a sharp drop in strength. Based on AE detection and scanning electron microscopy (SEM) image analysis, the failure process of silica fume foam concrete (SFFC) proceeds through three stages: free water evaporation at low temperatures, dehydration shrinkage of the C-S-H gel at medium temperatures, and finally, structural failure marked by the collapse of the C-S-H gel network at high temperatures. This study indicates that an SF content of 0.25% allows FC to achieve an optimal balance between mechanical properties and high-temperature stability. The findings provide a theoretical basis for optimizing FC mix proportions and enhancing fire prevention design. Full article

Radioactive contaminations in soil, which originate from nuclear power production, nuclear weapon testing, or uncontrolled release, are of great environmental concern. One of the major fission product contaminants is ⁹⁰Sr, whose high mobility demands a method to track contamination pathways and remediation processes. Positron emission tomography (PET) is a valuable tool for the required studies. As a β⁻/γ-emitter, ⁹⁰Sr is not suitable for PET, which requires β⁺-emitters. As an alternative, ⁸³Sr, with a 12% intensity of β⁺-emission and a half-life of 32.4 h, is an appropriate PET substitute for ⁹⁰Sr. We produced ⁸³Sr with an enriched target of [⁸⁵Rb]RbCl in a ⁸⁵Rb(p,3n)⁸³Sr reaction. The target material was bombarded with 36.22 MeV protons (ø 1.78 µA, 315 min), at a solid target station at the cyclotron U-120M (NPI CAS). The irradiated target (1.5 GBq) was dissolved in water, evaporated to dryness, redissolved in nitric acid, and transferred onto a Sr-selective cartridge (Sr-SpecTM, TRISKEM, France). Following target material wash out, ⁸³Sr elution with water, solvent evaporation, and reformulation (in dilute nitric acid) yielded 1.2 GBq (82% radiochemical extraction efficiency, non-decay-corrected) of an ⁸³Sr-solution. The easy and fast method is able to produce non-carrier-added ⁸³Sr with high radionuclidic purity. Full article

Global agricultural drought is evolving into a compound crisis threatening food security and ecological stability that is characterized by increased frequency, intensity, duration, and spatial extent. Since 2000, the global number of drought events has increased by 29% compared with the previous two decades, and 82% of drought-related losses in developing countries are concentrated in agriculture. The UNCCD (2022) projects that drought may affect up to three quarters of the world’s population by 2050. Climate change and human activities jointly drive this escalation through higher atmospheric evaporative demand, altered precipitation regimes, land use change, groundwater overexploitation, and pollution emissions. Their interaction forms amplifying feedback loops across ecology-agriculture and climate–agriculture systems, resulting in ecosystem degradation, crop yield loss, and rising socioeconomic inequality. Addressing this crisis requires a three-dimensional framework integrating mitigation, adaptation, and collaborative governance. This review synthesizes coupled driving mechanisms, cross-system impacts, and response pathways, and it also highlights priorities in compound-drought attribution, region-specific technology scaling, cross-scale governance, and resilience building in vulnerable regions. Full article

In this study, thermogravimetric analysis was employed to investigate the non-isothermal combustion behavior and kinetic characteristics of poplar biomass under air and oxy-fuel (O₂/CO₂) atmospheres. The effects of heating rate and oxygen concentration on combustion performance, gaseous emissions, and kinetic parameters were systematically analyzed. Results show that poplar biomass combustion consists of four distinct stages: moisture evaporation, devolatilization with volatile oxidation, char and fixed carbon oxidation, and final burnout. Increasing the heating rate intensifies the combustion process, shifting characteristic temperatures to higher values and significantly enhancing the comprehensive combustion index. Compared with air combustion, oxy-fuel conditions reduce ignition temperature and the temperature corresponding to the maximum combustion rate, leading to an earlier ignition and a more concentrated reaction interval. Higher oxygen concentrations further improve overall combustion performance and promote more complete carbon conversion. Gas emission analysis indicates that oxy-fuel combustion effectively suppresses NO₂ and SO₂ formation, demonstrating notable emission-reduction potential. Kinetic analysis using the Kissinger–Akahira–Sunose and Flynn–Wall–Ozawa isoconversional methods shows that the activation energy varies with conversion degree and is generally higher under oxy-fuel atmospheres than in air. Overall, oxy-fuel combustion enhances biomass reactivity while achieving coordinated emission control through increased oxygen partial pressure and improved heat and mass transfer, supporting its practical application in biomass energy systems. Full article

The evaporation of gasoline serves as an important contributor to volatile organic compounds (VOCs) within urban regions. However, most previous studies have focused on summertime gasoline evaporation, with relatively limited attention to wintertime emissions. Within the present research, online VOC monitoring was carried out at three urban locations across Beijing over the winter seasons of 2014–2015 and 2021–2022. A wintertime gasoline evaporation VOC source profile was established using enhancement ratio analysis and positive matrix factorization, based on observations at a site near a gasoline station. The results show that n-butane dominated wintertime gasoline evaporation VOCs (35%), exceeding i-pentane (20%), in contrast to the i-pentane dominance reported in previous studies. The chemical mass balance (CMB) model was then applied to apportion VOC sources and assess the sensitivity to different gasoline evaporation source profiles. Gasoline evaporation was found to contribute 12–17% of wintertime VOCs, 2.3–3 times higher than estimates based on the literature profiles. Comparisons between the winters of 2014–2015 and 2021–2022 reveal a 63% decrease in VOC concentrations, with the coal combustion contribution dropping by 85% and vehicular exhaust and gasoline evaporation by 51–60%. These findings demonstrate that gasoline evaporation remains a non-negligible VOC source in winter and highlight that season- and observation-based source profiles are essential for reliable VOC source apportionment and effective air quality management. Full article

In this study, continuous near-real-time measurements of greenhouse gases (GHGs), particularly carbon dioxide (CO₂) and methane (CH₄), and aerosol optical depth (AOD) were conducted at the Socheongcho Ocean Research Station (SORS) from January 2021 to April 2022. Specifically, AOD products retrieved from the Geo-KOMPSAT-2B sensors—Geostationary Environment Monitoring Spectrometer and Geostationary Ocean Color Imager II—were compared and validated against ground-based Aerosol Robotic Network (AERONET) observations. Both satellite products exhibited overall good agreement with AERONET AOD data and showed low bias. The GHG measurements based on cavity ring-down spectroscopy indicated that CO₂ reached its highest seasonal mean in the spring of 2022, while CH₄ attained its maximum during the wet summer of 2022. Temperature, relative humidity, and evaporation were closely associated with AOD variability during the dry summer period, while elevated temperatures may have contributed to enhanced photochemical activity and modulation of CH₄ concentrations. In the cold season, concurrent increases in GHGs and combustion-related pollutants (PM_2.5, CO, and black carbon) were observed, suggesting reduced oxidation capacity under stable atmospheric conditions. Overall, these findings underscore the potential value of integrating satellite and in situ observations to better characterize GHG–aerosol interactions and support emission mitigation strategies in the Northeast Asian marine environment. Full article

In this study, a bench test was conducted employing the Worldwide Harmonized Light-duty Vehicles Test Cycle (WLTC) to investigate the emission rates of hydrocarbons (HCs), carbon monoxide (CO), and carbon dioxide (CO₂) with two different gasolines and five gasoline vehicles. The results indicated that compared with X gasoline, X+ gasoline led to a reduction in the emission rates of HC, CO, and CO₂, by 38%, 11%, and 7%, respectively, attributed to its lower aromatic hydrocarbon content, olefin content, and 90% evaporation temperature (T90), and higher oxygen content. X+ gasoline exhibited more emission reductions under both acceleration and deceleration conditions. The two gasolines showed consistent patterns: for X+ gasoline, the emission rates under acceleration conditions were significantly higher than those under deceleration conditions, by a factor of 14.9, 2.1, and 1.6 for HC, CO, and CO₂, respectively. Stronger Spearman correlations between vehicle specific power (VSP) and the emission rates were observed at higher speed (>80 km/h) of X, than those at medium speed (40–80 km/h) and lower speed (≤40 km/h), for both gasolines. Overall, the grey relation analysis revealed obvious heterogeneity between each of the seven fuel properties (RON, T10, T50, T90, Oxygen content, Aromatics content, Olefin content) and each of the three emission rates. However, slightly higher relational degrees were observed between HC emissions and aromatics or olefin contents, highlighting the need for lowering aromatics and olefin contents, thus reducing HC emissions. Full article