Objective:To investigate the short and long tenn efficacy of a commercial air ionizer in killing Dermatophagoides pteronyssinus(D.pteronyssinus)and Dermalophagoides farinae(D.farinae)mites.Methods:The effect of a comm...Objective:To investigate the short and long tenn efficacy of a commercial air ionizer in killing Dermatophagoides pteronyssinus(D.pteronyssinus)and Dermalophagoides farinae(D.farinae)mites.Methods:The effect of a commercial ionizer on D.pteronyssinus and D.farinae was evaluated in the laboratory,using a specially designed test.Mortality was assessed after 6,16and 24 hours for direct exposure and after 24,36,48,60 and 72 hours for exposure in simulated mattress.New batches of mites were used for each exposure time.Results:LT_(50)for direct exposure of ionizer was 10 hours for D.pteronyssinus and 18 hours for D.farinae.The LT_(50)for exposure in simulated mattress was 132 hours or 5.5 days for D.pteronyssinus and 72 hours or 3days for D.farinae.LT_(95)for direct exposure of ionizer was 36 hours for D.pteronyssinus and D.farinae.Meanwhile,the LT_(95)for exposure in simulated mattress was 956 hours or 39.8 days for D.pteronyssinus and 403 hours or 16.8 days for D.farinae.Conclusions:This study demonstrates the increasing mite mortalities with increasing exposure time of a commercial ionizer and suggests that negative ions produced by an ionizer kill dust mites and can be used to reduce natural mile populations on exposed surfaces such as floors,clothes,curtains,etc.However,there is reduced efficacy on mites inside stuffed materials as in mattresses and furniture.展开更多
Infectious diseases(e.g.,coronavirus disease 2019)dramatically impact human life,economy and social development.Exploring the low-cost and energy-saving approaches is essential in removing infectious virus particles f...Infectious diseases(e.g.,coronavirus disease 2019)dramatically impact human life,economy and social development.Exploring the low-cost and energy-saving approaches is essential in removing infectious virus particles from indoors,such as in classrooms.The application of air purification devices,such as negative ion generators(ionizers),gains popularity because of the favorable removal capacity for particles and the low operation cost.However,small and portable ionizers have potential disadvantages in the removal efficiency owing to the limited horizontal diffusion of negative ions.This study aims to investigate the layout strategy(number and location)of ionizers based on the energy-efficient natural ventilation in the classroom to improve removal efficiency(negative ions to particles)and decrease infection risk.Three infected students were considered in the classroom.The simulations of negative ion and particle concentrations were performed and validated by the experiment.Results showed that as the number of ionizers was 4 and 5,the removal performance was largely improved by combining ionizer with natural ventilation.Compared with the scenario without an ionizer,the scenario with 5 ionizers largely increased the average removal efficiency from around 20%to 85%and decreased the average infection risk by 23%.The setup with 5 ionizers placed upstream of the classroom was determined as the optimal layout strategy,particularly when the location and number of the infected students were unknown.This work can provide a guideline for applying ionizers to public buildings when natural ventilation is used.展开更多
Abiotic oxygen formation predates photosynthesis,sustaining early chemical evolution,yet its elementary mechanisms remain contested.Here,we show the production pathways for molecular oxygen from doubly ionized carbon ...Abiotic oxygen formation predates photosynthesis,sustaining early chemical evolution,yet its elementary mechanisms remain contested.Here,we show the production pathways for molecular oxygen from doubly ionized carbon dioxide upon electron-impact.Through fragment ions and electron coincidence momentum imaging,we unambiguously determine the ionization mechanism by measuring the projectile energy loss in association with the C^(+) +O_(2)^(+) channel.Further potential energy and trajectory calculations enable us to elucidate the dynamical details of this fragmentation process,in which a bond rearrangement pathway is found to proceed via the structural deformation to a triangular intermediate.Moreover,we demonstrate a further roaming pathway for the formation of O_(2)^(+) from CO_(2)^(+) 2,in which a frustrated C-O bond cleavage leaves the O atom without sufficient energy to escape.The O atom then wanders around varied configuration spaces of the flat potential energy regions and forms a C-O-O_(2)^(+) intermediate prior to the final products C^(+) +O_(2)^(+).Considering the large quantities of free electrons in interstellar space,the processes revealed here are expected to be significant and should be incorporated into atmospheric evolution models.展开更多
Storm-enhanced density(SED)and the tongue of ionization(TOI)are key ionospheric storm-time structures whose rapid evolution and fine-scale variability remain challenging to capture with conventional empirical high-lat...Storm-enhanced density(SED)and the tongue of ionization(TOI)are key ionospheric storm-time structures whose rapid evolution and fine-scale variability remain challenging to capture with conventional empirical high-latitude drivers.In this study,we examine the May 10–11,2024,superstorm using the Thermosphere–Ionosphere–Electrodynamics General Circulation Model(TIEGCM)with observation-constrained high-latitude forcing.Auroral precipitation parameters(energy flux and mean energy)are assimilated from a Defense Meteorological Satellite Program(DMSP)Special Sensor Ultraviolet Spectrographic Imager(SSUSI)using a multi-resolution Gaussian process(Lattice Kriging)approach,whereas high-latitude convection potentials are derived by assimilating Super Dual Auroral Radar Network(SuperDARN)observations with the Thomas and Shepherd(2018)model(TS18).For comparison,an additional simulation is performed using empirical models for both convection and auroral forcing.The results show that during the main phase of the May 10 storm,the data-driven simulation provides a more realistic depiction of the SED source region than does the empirical model run by capturing its rapid intensification more clearly and reproducing its spatial location and structural features with higher fidelity.These improvements lead to a more accurate representation of its poleward extension into the polar cap that develops into the TOI.Above the ionospheric F2 peak over the SED source region,SuperDARN-constrained potentials generate stronger and more localized E×B drifts that dominate plasma uplift and drive its transport into the polar cap,although neutral winds and downward ambipolar diffusion partially offset these effects.Below the F2 peak,neutral winds and photochemical processes play a major role in shaping the spatial extent and intensity of the SED and TOI.These results highlight the role of observation-constrained high-latitude drivers in representing ionosphere–thermosphere responses during extreme storms and suggest their relevance for improving physical interpretation and model performance.展开更多
The development of collinear resonance ionization spectroscopy for studying the nuclear structure of nickel isotopes far from the stability line relies on high-efficiency two-color two-step photoionization pathways.We...The development of collinear resonance ionization spectroscopy for studying the nuclear structure of nickel isotopes far from the stability line relies on high-efficiency two-color two-step photoionization pathways.We systematically investigated the even-parity autoionization spectrum of atomic nickel through resonance ionization mass spectrometry(RIMS).Fifteen intense single-color photoionization lines and corresponding transitions in the 300-325 nm range were identified and excluded as potential interference peaks for subsequent two-color studies.Fifty-one even-parity autoionization states in the 64000-66800 cm^(-1)range were identified for the first time by scanning from five intermediate excited states of the3d^(8)(^(3)F)4s4p(^(3)P^(o))configuration.Forty-eight of these states were assigned unique total angular momentum quantum numbers(J)based on electric dipole transition selection rules.The autoionization state at 64437.77 cm^(-1)was identified as an optimal final state for enhancing photoionization efficiency in two-color two-step pathways.This study provides comprehensive datasets of even-parity autoionization states of nickel,supporting both the advancement of collinear resonance ionization spectroscopy for exotic nickel isotopes and theoretical modeling of autoionization states.The datasets are openly available at https://doi.org/10.57760/sciencedb.j00113.00280.展开更多
Organometallics play a vital role in catalytic and synthetic processes.Understanding the indi-vidual elementary steps of the reactions of organo metallic com-pounds is crucial for the development and ratio-nal design ...Organometallics play a vital role in catalytic and synthetic processes.Understanding the indi-vidual elementary steps of the reactions of organo metallic com-pounds is crucial for the development and ratio-nal design of new organometallic reagents and catalysts.Study of gas-phase reactions is one of the key approaches to probing the individual elementary steps under isolated and re-producible conditions.A series of investigations have been reported on the gas-phase reac-tions between organometallic ions and neutral molecules under room temperature conditions.However,studies about the reactions between organometallic ions and neutral molecules un-der heating conditions are very limited.In this work,an apparatus with an electrospray ion-ization source and an ion funnel trap,which can be coupled with a high-temperature linear ion trap reactor,was designed and built.The apparatus can be used to investigate the reac-tions between organometallic ions and neutral molecules under heating conditions.By using the apparatus,the adsorption reactions of Rh(PPh_(3))_(2)^(+)+CO→Rh(PPh_(3))_(2)CO^(+)and CuPPh_(3)^(+)+CO_(2)→CuPPh_(3)CO_(2)+under variable temperature conditions have been conducted.The experiments showed that the reaction rate constant of Rh(PPh_(3))_(2)^(+)+CO increases first and then decreases with increasing temperature.In contrast,the rate constant of CuPPh_(3)^(+)+CO_(2)decreases monotonically as the temperature increases.Density functional theory calculations indicate that the adsorption reaction of Rh(PPh_(3))_(2)^(+)+CO→Rh(PPh_(3))_(2)CO^(+)is subject to a small barrier,while CuPPh_(3)^(+)+CO_(2)→CuPPh_(3)CO_(2)+is barri-erless,which is consistent with the experimentally observed temperature-dependent rate con-stants.The newly built apparatus can thus provide new kinetic information to address reac-tion mechanisms for organometallic ions.展开更多
This study focuses on a 60 V trench MOSFET device designed for operation in space radiation environments.By increasing the bulk region concentration and placing the etched gate trench after the P+implantation process,...This study focuses on a 60 V trench MOSFET device designed for operation in space radiation environments.By increasing the bulk region concentration and placing the etched gate trench after the P+implantation process,we successfully reduced the threshold voltage shift from 6.5 to 2.2 V under a total dose of 400 krad(Si)^(60)Co,allowing the device to operate normally.Structurally,by embedding the source metal in the active and terminal regions,the device demonstrated current degradation without experiencing single-event burnout when subjected to a drain voltage of 60 V and a linear energy transfer value of 75.4 MeV·cm^(2)∕mg from tantalum-ion incidence.TCAD simulations verified that the embedded source metal effectively suppressed parasitic transistor conduction and eliminated the base-region expansion effect,thereby lowering the maximum temperature from 8000 to 1400 K.The irradiation effects of the embedded source metal in the terminal region were also investigated,which can improve the reverse recovery and ensure that the terminal metal does not melt prematurely,thereby significantly enhancing the radiation hardness of the device.展开更多
This article introduces a novel 20 V radiation-hardened high-voltage metal-oxide-semiconductor field-effect transistor(MOSFET)driver with an optimized input circuit and a drain-surrounding-source(DSS)structure.The inp...This article introduces a novel 20 V radiation-hardened high-voltage metal-oxide-semiconductor field-effect transistor(MOSFET)driver with an optimized input circuit and a drain-surrounding-source(DSS)structure.The input circuit of a conventional inverter consists of a thick-gate-oxide n-type MOSFET(NMOS).These conventional drivers can tolerate a total ionizing dose(TID)of up to 100 krad(Si).In contrast,the proposed comparator input circuit uses both a thick-gate-oxide p-type MOSFET(PMOS)and thin-gate-oxide NMOS to offer a high input voltage and higher TID tolerance.Because the thick-gate-oxide PMOS and thin-gate-oxide NMOS collectively provide better TID tolerance than the thick-gate-oxide NMOS,the circuit exhibits enhanced TID tolerance of>300 krad(Si).Simulations and experimental date indicate that the DSS structure reduces the probability of unwanted parasitic bipolar junction transistor activation,yielding a better single-event effect tolerance of over 81.8 MeVcm^(2)mg^(-1).The innovative strategy proposed in this study involves circuit and layout design optimization,and does not require any specialized process flow.Hence,the proposed circuit can be manufactured using common commercial 0.35μm BCD processes.展开更多
Formic and acetic acids are the most abundant gaseous organic acids and play the key role in the atmospheric chemistry.In iodine-adduct chemical ionizationmass spectrometry(CIMS),the low utilization efficiency of meth...Formic and acetic acids are the most abundant gaseous organic acids and play the key role in the atmospheric chemistry.In iodine-adduct chemical ionizationmass spectrometry(CIMS),the low utilization efficiency of methyl iodide and humidity interference are two major issues of the vacuum ultraviolet(VUV)lamp initiated CIMS for on-line gaseous formic and acetic acids analysis.In this work,we present a new CIMS based on VUV lamp,and the ion-molecular reactor is separated into photoionization and chemical ionization zones by a reducer electrode.Acetone was added to the photoionization zone,and the VUV photoionization acetone provided low-energy electrons for methyl iodide to generate I−,and the addition of acetone reduced the amount of methyl iodide by 2/3.In the chemical ionization zone,a headspace vial containing ultrapure water was added for humidity calibration,and the vial changes the sensitivity as a function of humidity from ambiguity to well linear correlation(R2>0.95).With humidity calibration,the CIMS can quantitatively measure formic and acetic acids in the humidity range of 0%-88%RH.In this mode,limits of detection of 10 and 50 pptv are obtained for formic and acetic acids,respectively.And the relative standard deviation(RSD)of quantitation stability for 6 days were less than 10.5%.This CIMS was successfully used to determine the formic and acetic acids in the underground parking and ambient environment of the Shandong University campus(Qingdao,China).In addition,we developed a simple model based formic acid concentration to assess vehicular emissions.展开更多
Accidental exposure to overdose ionizing radiation will inevitably lead to severe biological damage,thus detecting and localizing radiation is essential.Traditional measurement techniques are generally restricted to t...Accidental exposure to overdose ionizing radiation will inevitably lead to severe biological damage,thus detecting and localizing radiation is essential.Traditional measurement techniques are generally restricted to the detection range of few centimeters,posing a great risk to operators.The prospect in remote sensing makes femtosecond laser filament technology a great candidate for constructively addressing this challenge.Here we propose a novel filament-based ionizing radiation sensing method,and clarify the interaction mechanism between filaments and ionizing radiation from systematic experiment to microscopic theory.Specifically,it is demonstrated that the energetic electrons produced byαradiation in air can be effectively accelerated within the filament,serving as seed electrons,which will enhance nitrogen fluorescence.The extended nitrogen fluorescence lifetime of~1 ns is also observed.Lastly,the combined microscopic model was elaborately established to quantitatively explain the modulation of nitrogen fluorescence emission from filament by ionizing radiation.These findings provide insights into the intricate interaction among ultra-strong light field,plasma and energetic particle beam,potentially suggesting a promising novel avenue for remote sensing of ionizing radiation.展开更多
Strong feld-induced nonsequential double ionization(NSDI)is a signifcant multi-electron phenomenon that provides crucial insights into understanding electron correlation and multiple ionization of atoms and molecules,...Strong feld-induced nonsequential double ionization(NSDI)is a signifcant multi-electron phenomenon that provides crucial insights into understanding electron correlation and multiple ionization of atoms and molecules,but it is typically unattainable in a circularly polarized laser pulse,especially for long-wavelength lasers.We present evidence that NSDI can occur in the presence of a near-infrared or beyond laser pulse by introducing a bowtie-nanotip.The laser-induced local plasmon can alter the local ellipticity of the feld,thereby enabling NSDI through elliptical trajectories that facilitate recollisions with parent atoms.An oval-shaped momentum distribution of recoiled ions provides evidence for the modifcation of trajectories by the aligned nanotips.Our study introduces an innovative control knob to manipulate NSDI and electron dynamics through the utilization of nanostructures.展开更多
We present a fully time-dependent quantum wave packet evolution method for investigating molecular dynamics in intense laser fields.This approach enables the simultaneous treatment of interactions among multiple elect...We present a fully time-dependent quantum wave packet evolution method for investigating molecular dynamics in intense laser fields.This approach enables the simultaneous treatment of interactions among multiple electronic states while simultaneously tracking their time-dependent electronic,vibrational,and rotational dynamics.As an illustrative example,we consider neutral H_(2)molecules and simulate the laser-induced excitation dynamics of electronic and rotational states in strong laser fields,quantitatively distinguishing the respective contributions of electronic dipole transitions(within the classical-field approximation)and non-resonant Raman processes to the overall molecular dynamics.Furthermore,we precisely evaluate the relative contributions of direct tunneling ionization from the ground state and ionization following electronic excitation in the strong-field ionization of H_(2).The developed methodology shows strong potential for performing high-precision theoretical simulations of electronic-vibrational-rotational state excitations,ionization,and dissociation dynamics in molecules and their ions under intense laser fields.展开更多
This work describes the discharge characteristics and acetone degradation with plasma under different electric fields based on a coaxial cylindrical dielectric barrier discharge(DBD)device energized by pulsed power.It...This work describes the discharge characteristics and acetone degradation with plasma under different electric fields based on a coaxial cylindrical dielectric barrier discharge(DBD)device energized by pulsed power.It is found that the segmented electrodes with appropriate spacing in coaxial cylindrical DBD are beneficial to the plasma ionization.In this work,the plasma distribution,discharge thermal effect,ionization of reactive species,and acetone degradation performance in coaxial cylindrical DBD with different segmented electrodes are systematically investigated.The experimental results show that segmented electrodes with a certain distance can cause additional ionization in the non-electrode-covered region between adjacent electrodes,thus enlarging the plasma region compared with a single electrode with equivalent total electrode length.The additional ionization involved the inner volume discharge between the quartz tubes and the outer surface discharge along the surface of the external quartz tube.The spatial distributions of the inner volume discharge and external surface discharge were predominantly governed by the radial and axial components of the inter-electrode electric field,respectively.The external surface discharge exhibited significant suppression when the electrode spacing was<1.5 mm,and it reached its maximum length at 3 mm spacing.When the electrode distance increased to 7-9 mm,a weak ionizing region appeared in the middle of the adjacent electrodes,which could be attributed to the gradual attenuation of the radial component with the increasing electrode spacing.A higher thermal effect and better oxidation of acetone to CO_(x)(CO and CO_(2))were achieved with the segmented electrode;the dual-segment configuration(3 mm per electrode)achieved a reactor temperature of 63.4℃,representing a 10℃enhancement over comparable single-electrode systems.Similarly,the CO_(2)and CO concentration reached 328.8 mg/m3and 105.7 mg/m3,respectively,in two 3 mm long segmented electrodes,which was an increase of 12.2%and 25.6%,respectively,compared with the single electrode.Notably,considering the equivalent ionization of the inner discharge with different electrodes,the enhanced thermal effects and CO_(x)conversion efficiency directly correlate with the expanded plasma zone induced by electrode segmentation.This work provides critical insights into optimizing electrode configurations for efficient plasma-assisted volatile organic compound degradation systems.展开更多
Accurate classification of pulmonary nodules is critical for early diagnosis of lung cancer. However, non-invasive and accurate diagnosis of benign and malignant pulmonary nodules faces great challenges. In this study...Accurate classification of pulmonary nodules is critical for early diagnosis of lung cancer. However, non-invasive and accurate diagnosis of benign and malignant pulmonary nodules faces great challenges. In this study, we develop a nano zero-valent iron(nZVI)-assisted laser desorption/ionization mass spectrometry(LDI MS) platform, which enables ultra-high-throughput acquisition of abundant metabolic fingerprint information of serum in negative ion mode. We further recruit a large-scale multicenter prospective cohort and collect 1099 serum samples from participants with benign and malignant nodules. The accurate machine learning models are built and validated based on n ZVI-assisted LDI MS metabolomics to achieve efficient classification of benign and malignant nodules. Using our established stacking ensemble learning model, the AUC of the ROC curve for benign and malignant lung nodule classification can be as high as 0.9, and the sensitivity can reach 85.5%, which is significantly better than existing clinical models. This work provides an integrated workflow from detection technology to diagnostic models for biomarkerbased pulmonary nodule diagnosis, which would be widely used in rapid and large-scale screening of pulmonary nodules.展开更多
Introduction: The use of radioactive radiations in healthcare facilities must comply with radioprotection safety rules in order to avoid threatening the health of workers and patients. This study aimed to assess the w...Introduction: The use of radioactive radiations in healthcare facilities must comply with radioprotection safety rules in order to avoid threatening the health of workers and patients. This study aimed to assess the working conditions, the protective measures and the medical monitoring of workers directly involved in X-ray work at hospitals in Douala, Cameroon. Materials and Methods: A descriptive cross-sectional study was carried out during the 1st quarter of 2018, across various state and private health facilities of the city of Douala. Sampling was non-random, based on convenience and all the willing participants that fulfilled the inclusion criteria were enrolled. Quantitative analyses were conducted using EPI INFO 7.0 software and the results were presented in both univariate and bivariate forms. Results: The sample consisted of 56 men and 31 women with a mean age of 34.75 ± 8.77 years. X-ray technicians were over-represented (41.38%). Day/night shift work was the main work pattern (68.96%). The distribution of work zones A&B was known by 87.5% of the participants. Hazard warning signs were effective in work zones A and B (75.86%), and the walls of the premises were also reinforced in these work zones (88.51%), but the use of radiation dosimeters was rare (9.20%). Radiation aprons (94.30%) and hand-held dosimeters (63.20%) were the most commonly used personal protective equipment. The majority of the participants did not benefit from medical follow-up by an occupational health specialist (62.1%). Conclusion: The implementation of radiation protection measures remains a significant concern in Douala based health facilities, and requires stricter administrative controls and sanctions to prevent serious health consequences for exposed staff.展开更多
The emergence of high-temperature superconductivity in hydrogen-rich compounds has opened up promising avenues for investigating unique hydrogen motifs that exhibit exceptional superconducting properties.Nevertheless,...The emergence of high-temperature superconductivity in hydrogen-rich compounds has opened up promising avenues for investigating unique hydrogen motifs that exhibit exceptional superconducting properties.Nevertheless,the requirement for extremely high synthesis pressures poses significant barriers to experimentally probing potential physical properties.Here,we have designed a structure wherein NH_(3)tetrahedra are intercalated into the body-centered cubic lattice of Yb,resulting in the formation of Yb(NH_(3))_(4).Our first-principles calculations reveal that metallic behavior emerges from the ionization of sp^(3)-hybridized s-bonds in NH_(3),which is enabled by electron transfer from ytterbium orbitals to NH_(3)anti-bonding s-orbitals.A distinctive feature of this structure is the Fermi surface nesting,which leads to optical phonon softening and consequently enhances electron-phonon coupling.The subsequent density-functional theory(DFT)calculations demonstrate that this I-43m phase of Yb(NH_(3))4 exhibits a superconducting critical temperature(T_(c))of 17.32 K under a modest pressure of 10 GPa.Our investigation presents perspectives on achieving phonon-mediated superconductivity at relatively low pressures,thereby opening up extensive possibilities for the attainment of high-temperature superconductivity in hydrogen-based superconducting systems with specific ionized molecular groups.展开更多
Bone marrow serves as the life-long home for hemato-poietic stem cells(HSCs)and is the most radio-sensitive organ^([1]).Acute ionizing radiation exceeding 1 Gray(Gy)causes severe damage in bone marrow while no effecti...Bone marrow serves as the life-long home for hemato-poietic stem cells(HSCs)and is the most radio-sensitive organ^([1]).Acute ionizing radiation exceeding 1 Gray(Gy)causes severe damage in bone marrow while no effective drug has been approved in clinical.In a recent work pub-lished in MedComm,Gao and her team reported,for the first time,cannabidiol(CBD)as an outstanding radioprotection agent targeting acute radiation-induced hematopoietic injury^([2]).Within two weeks post radiation,CBD can pro-mote the stemness of hematopoietic stem cells to a regular level.Using single-cell RNA sequencing(scRNA-seq)and functional assay,the authors decoded molecular changes underlying radiation-induced damage and CBD-induced recovery in HSCs.展开更多
Traditional electrospray ionization tandem mass spectrometry(ESI-MS^(n))has been a powerful tool in diverse research areas,however,it faces great limitations in the study of protein-small molecule interactions.In this...Traditional electrospray ionization tandem mass spectrometry(ESI-MS^(n))has been a powerful tool in diverse research areas,however,it faces great limitations in the study of protein-small molecule interactions.In this article,the state-of-the-art temperature-controlled electrospray ionization tandem mass spectrometry(TC-ESI-MS^(n))is applied to investigate interactions between ubiquitin and two flavonol molecules,respectively.The combination of collision-induced dissociation(CID)and MS solution-melting experiments facilitates the understanding of flavonol-protein interactions in a new dimension across varying temperature ranges.While structural changes of proteins disturbed by small molecules are unseen in ESI-MS^(n),TC-ESI-MS^(n)allows a simultaneous assessment of the stability of the complex in both gas and liquid phases under various temperature conditions,meanwhile investigating the impact on the protein’s structure and tracking changes in thermodynamic data,and the characteristics of structural intermediates.展开更多
Ionizing radiation presents an important solution for virus inactivation.However,its efficacy for severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)inactivation and the underlying mechanisms remain unclear.Th...Ionizing radiation presents an important solution for virus inactivation.However,its efficacy for severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)inactivation and the underlying mechanisms remain unclear.This study demonstrates radiosensitivity and radiation-induced biological changes in SARS-CoV-2 using 20 wild-type and mutant strains.The results show that 1.2 kGy of electron beam(E-beam)or 0.9 kGy of X-ray irradiation can eliminate 99.99%of SARS-CoV-2 particles.The Delta and various Omicron variants exhibit heightened sensitivity to radiation compared to the wild-type,showing nearly 99.99%inactivation efficiency at 1.0 and 0.8 kGy.The relationship between irradiation dose and the logarithmic reduction in virus load adheres to a dose-response model,characterized by extremely narrow windows.Spike(S)protein disruption,rather than the commonly accepted nucleic acid cleavage,is identified as the primary inactivation mechanism(triggering a conformation transition of S protein from pre-fusion to post-fusion with minimal impact on nucleic acid integrity).This study introduces the concept of targeting critical proteins in coronavirus inactivation,offering valuable insight for infectious coronavirus disease control and vaccine development.展开更多
In past decades,ABX_(3) halide perovskites have attracted great interest in solar cells due to excellent opto-electronic properties,such as high carrier mobility.However,instability and toxicity are obstacles on the c...In past decades,ABX_(3) halide perovskites have attracted great interest in solar cells due to excellent opto-electronic properties,such as high carrier mobility.However,instability and toxicity are obstacles on the commercial route for perovskites.Many studies have turned to exploring A_(2) BX_(6) and A_(3) B_(2) X_(9) for better stability.Unfortunately,the carrier mobilities of these two types are inferior to ABX_(3),lower by an order of magnitude.Furthermore,the mobility of ABX_(3) is distributed over a large range of 1.78-4500 cm^(2) V^(−1) s^(−1) in experiments,which contributes to another diversity of mobilities.In this paper,we aim at reveal-ing the physical origin of the above-mentioned diversities by theoretical studies on CsBX_(3),Cs_(2) BX_(6),and Cs_(3) B_(2) X_(9)(B=Sn,Pb,Sb,Bi,X=Br,Cl).The difference in group velocities is the major reason responsible for the variation in these types.The unique three-dimensional connected conductive network of CsBX_(3) determines its large group velocity.As for carrier scattering,ionized impurity scattering dominates at low carrier and high ionized impurity concentrations.Detailed analysis reveals that band degeneracy is strongly related to the impurity scattering rate,while dielectric constant is almost immune.Our study provides a better understanding of the relationship between electronic structures and mobilities for po-tential applications in photovoltaics.展开更多
文摘Objective:To investigate the short and long tenn efficacy of a commercial air ionizer in killing Dermatophagoides pteronyssinus(D.pteronyssinus)and Dermalophagoides farinae(D.farinae)mites.Methods:The effect of a commercial ionizer on D.pteronyssinus and D.farinae was evaluated in the laboratory,using a specially designed test.Mortality was assessed after 6,16and 24 hours for direct exposure and after 24,36,48,60 and 72 hours for exposure in simulated mattress.New batches of mites were used for each exposure time.Results:LT_(50)for direct exposure of ionizer was 10 hours for D.pteronyssinus and 18 hours for D.farinae.The LT_(50)for exposure in simulated mattress was 132 hours or 5.5 days for D.pteronyssinus and 72 hours or 3days for D.farinae.LT_(95)for direct exposure of ionizer was 36 hours for D.pteronyssinus and D.farinae.Meanwhile,the LT_(95)for exposure in simulated mattress was 956 hours or 39.8 days for D.pteronyssinus and 403 hours or 16.8 days for D.farinae.Conclusions:This study demonstrates the increasing mite mortalities with increasing exposure time of a commercial ionizer and suggests that negative ions produced by an ionizer kill dust mites and can be used to reduce natural mile populations on exposed surfaces such as floors,clothes,curtains,etc.However,there is reduced efficacy on mites inside stuffed materials as in mattresses and furniture.
基金supports from the National Natural Science Funds for Distinguished Young Scholar(No.52225005)the National Natural Science Foundation of China(No.52178069)+2 种基金the Fundamental Research Funds for the Central Universities(No.4301002171)Concordia University-Canada,through the Concordia Research Chair-Energy&Environment,and the support received through the Engineering and Physical Sciences Research Council(EPSRC)–funded CO-TRACE(COvid-19 Transmission Risk Assessment Case studiesEducation Establishments,EP/W001411/1)the COVAIR(Is SARS-CoV-2 airborne and does it interact with particle pollutants?,EP/V052462/1)projects,and“Knowledge Transfer and Practical application of research on Indoor Air Quality(KTP-IAQ)”project that is funded by the University of Surrey’s Research England funding under the Global Challenge Research Fund(GCRF).
文摘Infectious diseases(e.g.,coronavirus disease 2019)dramatically impact human life,economy and social development.Exploring the low-cost and energy-saving approaches is essential in removing infectious virus particles from indoors,such as in classrooms.The application of air purification devices,such as negative ion generators(ionizers),gains popularity because of the favorable removal capacity for particles and the low operation cost.However,small and portable ionizers have potential disadvantages in the removal efficiency owing to the limited horizontal diffusion of negative ions.This study aims to investigate the layout strategy(number and location)of ionizers based on the energy-efficient natural ventilation in the classroom to improve removal efficiency(negative ions to particles)and decrease infection risk.Three infected students were considered in the classroom.The simulations of negative ion and particle concentrations were performed and validated by the experiment.Results showed that as the number of ionizers was 4 and 5,the removal performance was largely improved by combining ionizer with natural ventilation.Compared with the scenario without an ionizer,the scenario with 5 ionizers largely increased the average removal efficiency from around 20%to 85%and decreased the average infection risk by 23%.The setup with 5 ionizers placed upstream of the classroom was determined as the optimal layout strategy,particularly when the location and number of the infected students were unknown.This work can provide a guideline for applying ionizers to public buildings when natural ventilation is used.
基金supported by the National Natural Science Foundation of China (Grant Nos.12325406,92261201,12404305,and W2512072)the Shaanxi Province Natural Science Fundamental Research Project (Grant Nos.2023JC-XJ-03 and23JSQ013)the China Postdoctoral Science Foundation (Grant Nos.BX20240286 and 2024M7625)。
文摘Abiotic oxygen formation predates photosynthesis,sustaining early chemical evolution,yet its elementary mechanisms remain contested.Here,we show the production pathways for molecular oxygen from doubly ionized carbon dioxide upon electron-impact.Through fragment ions and electron coincidence momentum imaging,we unambiguously determine the ionization mechanism by measuring the projectile energy loss in association with the C^(+) +O_(2)^(+) channel.Further potential energy and trajectory calculations enable us to elucidate the dynamical details of this fragmentation process,in which a bond rearrangement pathway is found to proceed via the structural deformation to a triangular intermediate.Moreover,we demonstrate a further roaming pathway for the formation of O_(2)^(+) from CO_(2)^(+) 2,in which a frustrated C-O bond cleavage leaves the O atom without sufficient energy to escape.The O atom then wanders around varied configuration spaces of the flat potential energy regions and forms a C-O-O_(2)^(+) intermediate prior to the final products C^(+) +O_(2)^(+).Considering the large quantities of free electrons in interstellar space,the processes revealed here are expected to be significant and should be incorporated into atmospheric evolution models.
基金The Shandong Provincial Natural Science Foundation(Grant No.ZR2022JQ18)supported this worksupported by the National Natural Science Foundation of China(NNFSC)Youth Program(Grant No.42304168)+1 种基金supported by the National Key R&D Program of China(Grant No.2022YFF0504400)the NNSFC(Grant Nos.42188101 and 42174210)。
文摘Storm-enhanced density(SED)and the tongue of ionization(TOI)are key ionospheric storm-time structures whose rapid evolution and fine-scale variability remain challenging to capture with conventional empirical high-latitude drivers.In this study,we examine the May 10–11,2024,superstorm using the Thermosphere–Ionosphere–Electrodynamics General Circulation Model(TIEGCM)with observation-constrained high-latitude forcing.Auroral precipitation parameters(energy flux and mean energy)are assimilated from a Defense Meteorological Satellite Program(DMSP)Special Sensor Ultraviolet Spectrographic Imager(SSUSI)using a multi-resolution Gaussian process(Lattice Kriging)approach,whereas high-latitude convection potentials are derived by assimilating Super Dual Auroral Radar Network(SuperDARN)observations with the Thomas and Shepherd(2018)model(TS18).For comparison,an additional simulation is performed using empirical models for both convection and auroral forcing.The results show that during the main phase of the May 10 storm,the data-driven simulation provides a more realistic depiction of the SED source region than does the empirical model run by capturing its rapid intensification more clearly and reproducing its spatial location and structural features with higher fidelity.These improvements lead to a more accurate representation of its poleward extension into the polar cap that develops into the TOI.Above the ionospheric F2 peak over the SED source region,SuperDARN-constrained potentials generate stronger and more localized E×B drifts that dominate plasma uplift and drive its transport into the polar cap,although neutral winds and downward ambipolar diffusion partially offset these effects.Below the F2 peak,neutral winds and photochemical processes play a major role in shaping the spatial extent and intensity of the SED and TOI.These results highlight the role of observation-constrained high-latitude drivers in representing ionosphere–thermosphere responses during extreme storms and suggest their relevance for improving physical interpretation and model performance.
基金supported by the China National Nuclear Corporation Basic Research Project(Grant No.CNNC-JCYJ-202327)。
文摘The development of collinear resonance ionization spectroscopy for studying the nuclear structure of nickel isotopes far from the stability line relies on high-efficiency two-color two-step photoionization pathways.We systematically investigated the even-parity autoionization spectrum of atomic nickel through resonance ionization mass spectrometry(RIMS).Fifteen intense single-color photoionization lines and corresponding transitions in the 300-325 nm range were identified and excluded as potential interference peaks for subsequent two-color studies.Fifty-one even-parity autoionization states in the 64000-66800 cm^(-1)range were identified for the first time by scanning from five intermediate excited states of the3d^(8)(^(3)F)4s4p(^(3)P^(o))configuration.Forty-eight of these states were assigned unique total angular momentum quantum numbers(J)based on electric dipole transition selection rules.The autoionization state at 64437.77 cm^(-1)was identified as an optimal final state for enhancing photoionization efficiency in two-color two-step pathways.This study provides comprehensive datasets of even-parity autoionization states of nickel,supporting both the advancement of collinear resonance ionization spectroscopy for exotic nickel isotopes and theoretical modeling of autoionization states.The datasets are openly available at https://doi.org/10.57760/sciencedb.j00113.00280.
基金supported by the National Natural Science Foundation of China(Nos.92461313 and 22121002)the National Key R&D Program of China(No.2021YFA1500704).
文摘Organometallics play a vital role in catalytic and synthetic processes.Understanding the indi-vidual elementary steps of the reactions of organo metallic com-pounds is crucial for the development and ratio-nal design of new organometallic reagents and catalysts.Study of gas-phase reactions is one of the key approaches to probing the individual elementary steps under isolated and re-producible conditions.A series of investigations have been reported on the gas-phase reac-tions between organometallic ions and neutral molecules under room temperature conditions.However,studies about the reactions between organometallic ions and neutral molecules un-der heating conditions are very limited.In this work,an apparatus with an electrospray ion-ization source and an ion funnel trap,which can be coupled with a high-temperature linear ion trap reactor,was designed and built.The apparatus can be used to investigate the reac-tions between organometallic ions and neutral molecules under heating conditions.By using the apparatus,the adsorption reactions of Rh(PPh_(3))_(2)^(+)+CO→Rh(PPh_(3))_(2)CO^(+)and CuPPh_(3)^(+)+CO_(2)→CuPPh_(3)CO_(2)+under variable temperature conditions have been conducted.The experiments showed that the reaction rate constant of Rh(PPh_(3))_(2)^(+)+CO increases first and then decreases with increasing temperature.In contrast,the rate constant of CuPPh_(3)^(+)+CO_(2)decreases monotonically as the temperature increases.Density functional theory calculations indicate that the adsorption reaction of Rh(PPh_(3))_(2)^(+)+CO→Rh(PPh_(3))_(2)CO^(+)is subject to a small barrier,while CuPPh_(3)^(+)+CO_(2)→CuPPh_(3)CO_(2)+is barri-erless,which is consistent with the experimentally observed temperature-dependent rate con-stants.The newly built apparatus can thus provide new kinetic information to address reac-tion mechanisms for organometallic ions.
基金supported in part by National R&D Program for Major Research Instruments of China(No.62027814)。
文摘This study focuses on a 60 V trench MOSFET device designed for operation in space radiation environments.By increasing the bulk region concentration and placing the etched gate trench after the P+implantation process,we successfully reduced the threshold voltage shift from 6.5 to 2.2 V under a total dose of 400 krad(Si)^(60)Co,allowing the device to operate normally.Structurally,by embedding the source metal in the active and terminal regions,the device demonstrated current degradation without experiencing single-event burnout when subjected to a drain voltage of 60 V and a linear energy transfer value of 75.4 MeV·cm^(2)∕mg from tantalum-ion incidence.TCAD simulations verified that the embedded source metal effectively suppressed parasitic transistor conduction and eliminated the base-region expansion effect,thereby lowering the maximum temperature from 8000 to 1400 K.The irradiation effects of the embedded source metal in the terminal region were also investigated,which can improve the reverse recovery and ensure that the terminal metal does not melt prematurely,thereby significantly enhancing the radiation hardness of the device.
基金supported by the National Natural Science Foundation of China(U2241221).
文摘This article introduces a novel 20 V radiation-hardened high-voltage metal-oxide-semiconductor field-effect transistor(MOSFET)driver with an optimized input circuit and a drain-surrounding-source(DSS)structure.The input circuit of a conventional inverter consists of a thick-gate-oxide n-type MOSFET(NMOS).These conventional drivers can tolerate a total ionizing dose(TID)of up to 100 krad(Si).In contrast,the proposed comparator input circuit uses both a thick-gate-oxide p-type MOSFET(PMOS)and thin-gate-oxide NMOS to offer a high input voltage and higher TID tolerance.Because the thick-gate-oxide PMOS and thin-gate-oxide NMOS collectively provide better TID tolerance than the thick-gate-oxide NMOS,the circuit exhibits enhanced TID tolerance of>300 krad(Si).Simulations and experimental date indicate that the DSS structure reduces the probability of unwanted parasitic bipolar junction transistor activation,yielding a better single-event effect tolerance of over 81.8 MeVcm^(2)mg^(-1).The innovative strategy proposed in this study involves circuit and layout design optimization,and does not require any specialized process flow.Hence,the proposed circuit can be manufactured using common commercial 0.35μm BCD processes.
基金supported by the National Special Fund for the Development of Major Research Equipment and Instrument(No.2020YFF01014503)the Young Taishan Scholars(No.tsqn201909039)the College 20 Project fromJi Nan Science&Technology Bureau(No.2021GXRC058).
文摘Formic and acetic acids are the most abundant gaseous organic acids and play the key role in the atmospheric chemistry.In iodine-adduct chemical ionizationmass spectrometry(CIMS),the low utilization efficiency of methyl iodide and humidity interference are two major issues of the vacuum ultraviolet(VUV)lamp initiated CIMS for on-line gaseous formic and acetic acids analysis.In this work,we present a new CIMS based on VUV lamp,and the ion-molecular reactor is separated into photoionization and chemical ionization zones by a reducer electrode.Acetone was added to the photoionization zone,and the VUV photoionization acetone provided low-energy electrons for methyl iodide to generate I−,and the addition of acetone reduced the amount of methyl iodide by 2/3.In the chemical ionization zone,a headspace vial containing ultrapure water was added for humidity calibration,and the vial changes the sensitivity as a function of humidity from ambiguity to well linear correlation(R2>0.95).With humidity calibration,the CIMS can quantitatively measure formic and acetic acids in the humidity range of 0%-88%RH.In this mode,limits of detection of 10 and 50 pptv are obtained for formic and acetic acids,respectively.And the relative standard deviation(RSD)of quantitation stability for 6 days were less than 10.5%.This CIMS was successfully used to determine the formic and acetic acids in the underground parking and ambient environment of the Shandong University campus(Qingdao,China).In addition,we developed a simple model based formic acid concentration to assess vehicular emissions.
基金financial supports from National Key Research and Development Program of China(2024YFB3613900)National Natural Science Foundation of China(W2412044)+1 种基金Russian Science Foundation(25-4900154)Fundamental Research Funds for the Central Universities(63253214)。
文摘Accidental exposure to overdose ionizing radiation will inevitably lead to severe biological damage,thus detecting and localizing radiation is essential.Traditional measurement techniques are generally restricted to the detection range of few centimeters,posing a great risk to operators.The prospect in remote sensing makes femtosecond laser filament technology a great candidate for constructively addressing this challenge.Here we propose a novel filament-based ionizing radiation sensing method,and clarify the interaction mechanism between filaments and ionizing radiation from systematic experiment to microscopic theory.Specifically,it is demonstrated that the energetic electrons produced byαradiation in air can be effectively accelerated within the filament,serving as seed electrons,which will enhance nitrogen fluorescence.The extended nitrogen fluorescence lifetime of~1 ns is also observed.Lastly,the combined microscopic model was elaborately established to quantitatively explain the modulation of nitrogen fluorescence emission from filament by ionizing radiation.These findings provide insights into the intricate interaction among ultra-strong light field,plasma and energetic particle beam,potentially suggesting a promising novel avenue for remote sensing of ionizing radiation.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFE0134200)the National Natural Science Foundation of China(Grant Nos.12474343,12174147,and 12074142)the Natural Science Foundation of Jilin Province,China(Grant No.20220101016JC)。
文摘Strong feld-induced nonsequential double ionization(NSDI)is a signifcant multi-electron phenomenon that provides crucial insights into understanding electron correlation and multiple ionization of atoms and molecules,but it is typically unattainable in a circularly polarized laser pulse,especially for long-wavelength lasers.We present evidence that NSDI can occur in the presence of a near-infrared or beyond laser pulse by introducing a bowtie-nanotip.The laser-induced local plasmon can alter the local ellipticity of the feld,thereby enabling NSDI through elliptical trajectories that facilitate recollisions with parent atoms.An oval-shaped momentum distribution of recoiled ions provides evidence for the modifcation of trajectories by the aligned nanotips.Our study introduces an innovative control knob to manipulate NSDI and electron dynamics through the utilization of nanostructures.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1602502)the National Natural Science Foundation of China(Grant No.12450404)。
文摘We present a fully time-dependent quantum wave packet evolution method for investigating molecular dynamics in intense laser fields.This approach enables the simultaneous treatment of interactions among multiple electronic states while simultaneously tracking their time-dependent electronic,vibrational,and rotational dynamics.As an illustrative example,we consider neutral H_(2)molecules and simulate the laser-induced excitation dynamics of electronic and rotational states in strong laser fields,quantitatively distinguishing the respective contributions of electronic dipole transitions(within the classical-field approximation)and non-resonant Raman processes to the overall molecular dynamics.Furthermore,we precisely evaluate the relative contributions of direct tunneling ionization from the ground state and ionization following electronic excitation in the strong-field ionization of H_(2).The developed methodology shows strong potential for performing high-precision theoretical simulations of electronic-vibrational-rotational state excitations,ionization,and dissociation dynamics in molecules and their ions under intense laser fields.
文摘This work describes the discharge characteristics and acetone degradation with plasma under different electric fields based on a coaxial cylindrical dielectric barrier discharge(DBD)device energized by pulsed power.It is found that the segmented electrodes with appropriate spacing in coaxial cylindrical DBD are beneficial to the plasma ionization.In this work,the plasma distribution,discharge thermal effect,ionization of reactive species,and acetone degradation performance in coaxial cylindrical DBD with different segmented electrodes are systematically investigated.The experimental results show that segmented electrodes with a certain distance can cause additional ionization in the non-electrode-covered region between adjacent electrodes,thus enlarging the plasma region compared with a single electrode with equivalent total electrode length.The additional ionization involved the inner volume discharge between the quartz tubes and the outer surface discharge along the surface of the external quartz tube.The spatial distributions of the inner volume discharge and external surface discharge were predominantly governed by the radial and axial components of the inter-electrode electric field,respectively.The external surface discharge exhibited significant suppression when the electrode spacing was<1.5 mm,and it reached its maximum length at 3 mm spacing.When the electrode distance increased to 7-9 mm,a weak ionizing region appeared in the middle of the adjacent electrodes,which could be attributed to the gradual attenuation of the radial component with the increasing electrode spacing.A higher thermal effect and better oxidation of acetone to CO_(x)(CO and CO_(2))were achieved with the segmented electrode;the dual-segment configuration(3 mm per electrode)achieved a reactor temperature of 63.4℃,representing a 10℃enhancement over comparable single-electrode systems.Similarly,the CO_(2)and CO concentration reached 328.8 mg/m3and 105.7 mg/m3,respectively,in two 3 mm long segmented electrodes,which was an increase of 12.2%and 25.6%,respectively,compared with the single electrode.Notably,considering the equivalent ionization of the inner discharge with different electrodes,the enhanced thermal effects and CO_(x)conversion efficiency directly correlate with the expanded plasma zone induced by electrode segmentation.This work provides critical insights into optimizing electrode configurations for efficient plasma-assisted volatile organic compound degradation systems.
基金financially supported by the Fundamental Research Funds for the Central Universities (No. WHU 2042024kf0009)National Key Research and Development Program of China (No. 2021YFC2700700)the National Natural Science Foundation of China (Nos. 22074111, 22004093)。
文摘Accurate classification of pulmonary nodules is critical for early diagnosis of lung cancer. However, non-invasive and accurate diagnosis of benign and malignant pulmonary nodules faces great challenges. In this study, we develop a nano zero-valent iron(nZVI)-assisted laser desorption/ionization mass spectrometry(LDI MS) platform, which enables ultra-high-throughput acquisition of abundant metabolic fingerprint information of serum in negative ion mode. We further recruit a large-scale multicenter prospective cohort and collect 1099 serum samples from participants with benign and malignant nodules. The accurate machine learning models are built and validated based on n ZVI-assisted LDI MS metabolomics to achieve efficient classification of benign and malignant nodules. Using our established stacking ensemble learning model, the AUC of the ROC curve for benign and malignant lung nodule classification can be as high as 0.9, and the sensitivity can reach 85.5%, which is significantly better than existing clinical models. This work provides an integrated workflow from detection technology to diagnostic models for biomarkerbased pulmonary nodule diagnosis, which would be widely used in rapid and large-scale screening of pulmonary nodules.
文摘Introduction: The use of radioactive radiations in healthcare facilities must comply with radioprotection safety rules in order to avoid threatening the health of workers and patients. This study aimed to assess the working conditions, the protective measures and the medical monitoring of workers directly involved in X-ray work at hospitals in Douala, Cameroon. Materials and Methods: A descriptive cross-sectional study was carried out during the 1st quarter of 2018, across various state and private health facilities of the city of Douala. Sampling was non-random, based on convenience and all the willing participants that fulfilled the inclusion criteria were enrolled. Quantitative analyses were conducted using EPI INFO 7.0 software and the results were presented in both univariate and bivariate forms. Results: The sample consisted of 56 men and 31 women with a mean age of 34.75 ± 8.77 years. X-ray technicians were over-represented (41.38%). Day/night shift work was the main work pattern (68.96%). The distribution of work zones A&B was known by 87.5% of the participants. Hazard warning signs were effective in work zones A and B (75.86%), and the walls of the premises were also reinforced in these work zones (88.51%), but the use of radiation dosimeters was rare (9.20%). Radiation aprons (94.30%) and hand-held dosimeters (63.20%) were the most commonly used personal protective equipment. The majority of the participants did not benefit from medical follow-up by an occupational health specialist (62.1%). Conclusion: The implementation of radiation protection measures remains a significant concern in Douala based health facilities, and requires stricter administrative controls and sanctions to prevent serious health consequences for exposed staff.
基金work was supported by the National Key Research and Development Program of China(Grant Nos.2023YFA1406200 and 2022YFA1405500)the National Natural Science Foundation of China(Grant Nos.12304021 and 52072188)+4 种基金Zhejiang Provincial Natural Science Foundation of China(Grant No.LQ23A040004)Program for Science and Technology Innovation Team in Zhejiang(Grant No.2021R01004)the Natural Science Foundation of Ningbo(Grant No.2022J091)the Program for Changjiang Scholars and Innovative Research Team in University(Grant No.IRT 15R23)Parts of calculations were performed at the Supercomputer Center of Ningbo University.
文摘The emergence of high-temperature superconductivity in hydrogen-rich compounds has opened up promising avenues for investigating unique hydrogen motifs that exhibit exceptional superconducting properties.Nevertheless,the requirement for extremely high synthesis pressures poses significant barriers to experimentally probing potential physical properties.Here,we have designed a structure wherein NH_(3)tetrahedra are intercalated into the body-centered cubic lattice of Yb,resulting in the formation of Yb(NH_(3))_(4).Our first-principles calculations reveal that metallic behavior emerges from the ionization of sp^(3)-hybridized s-bonds in NH_(3),which is enabled by electron transfer from ytterbium orbitals to NH_(3)anti-bonding s-orbitals.A distinctive feature of this structure is the Fermi surface nesting,which leads to optical phonon softening and consequently enhances electron-phonon coupling.The subsequent density-functional theory(DFT)calculations demonstrate that this I-43m phase of Yb(NH_(3))4 exhibits a superconducting critical temperature(T_(c))of 17.32 K under a modest pressure of 10 GPa.Our investigation presents perspectives on achieving phonon-mediated superconductivity at relatively low pressures,thereby opening up extensive possibilities for the attainment of high-temperature superconductivity in hydrogen-based superconducting systems with specific ionized molecular groups.
文摘Bone marrow serves as the life-long home for hemato-poietic stem cells(HSCs)and is the most radio-sensitive organ^([1]).Acute ionizing radiation exceeding 1 Gray(Gy)causes severe damage in bone marrow while no effective drug has been approved in clinical.In a recent work pub-lished in MedComm,Gao and her team reported,for the first time,cannabidiol(CBD)as an outstanding radioprotection agent targeting acute radiation-induced hematopoietic injury^([2]).Within two weeks post radiation,CBD can pro-mote the stemness of hematopoietic stem cells to a regular level.Using single-cell RNA sequencing(scRNA-seq)and functional assay,the authors decoded molecular changes underlying radiation-induced damage and CBD-induced recovery in HSCs.
基金supports by the National Natural Science Foundation of China(No.22174037)the Joint Funds of the Hunan Provincial Natural Science Foundation of China(No.2023JJ50255)+1 种基金Changsha Science and Technology Project(No.Z202269490128)National Key Research and Development Program of China(No.2023YFF0613400)are appreciated.
文摘Traditional electrospray ionization tandem mass spectrometry(ESI-MS^(n))has been a powerful tool in diverse research areas,however,it faces great limitations in the study of protein-small molecule interactions.In this article,the state-of-the-art temperature-controlled electrospray ionization tandem mass spectrometry(TC-ESI-MS^(n))is applied to investigate interactions between ubiquitin and two flavonol molecules,respectively.The combination of collision-induced dissociation(CID)and MS solution-melting experiments facilitates the understanding of flavonol-protein interactions in a new dimension across varying temperature ranges.While structural changes of proteins disturbed by small molecules are unseen in ESI-MS^(n),TC-ESI-MS^(n)allows a simultaneous assessment of the stability of the complex in both gas and liquid phases under various temperature conditions,meanwhile investigating the impact on the protein’s structure and tracking changes in thermodynamic data,and the characteristics of structural intermediates.
基金supported by the National Key Research and Development Program of China(2024YFC2309900 and 2021YFC2301200)the Zhejiang Plan for the Special Support for Top-notch Talents in China(2022R52029)+1 种基金the Fundamental Research Funds for the Central Universities(2022ZFJH003)the Hangzhou Global Scientific and Technological Innovation Center of Zhejiang University(KC2021ZY0B0002).
文摘Ionizing radiation presents an important solution for virus inactivation.However,its efficacy for severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)inactivation and the underlying mechanisms remain unclear.This study demonstrates radiosensitivity and radiation-induced biological changes in SARS-CoV-2 using 20 wild-type and mutant strains.The results show that 1.2 kGy of electron beam(E-beam)or 0.9 kGy of X-ray irradiation can eliminate 99.99%of SARS-CoV-2 particles.The Delta and various Omicron variants exhibit heightened sensitivity to radiation compared to the wild-type,showing nearly 99.99%inactivation efficiency at 1.0 and 0.8 kGy.The relationship between irradiation dose and the logarithmic reduction in virus load adheres to a dose-response model,characterized by extremely narrow windows.Spike(S)protein disruption,rather than the commonly accepted nucleic acid cleavage,is identified as the primary inactivation mechanism(triggering a conformation transition of S protein from pre-fusion to post-fusion with minimal impact on nucleic acid integrity).This study introduces the concept of targeting critical proteins in coronavirus inactivation,offering valuable insight for infectious coronavirus disease control and vaccine development.
基金supported by the National Key Research and Development Program of China(No.2021YFB3502200)the National Natural Science Foundation of China(Nos.52172216 and 92163212)+1 种基金support from the Shanghai Engi-neering Research Center for Integrated Circuits and Advanced Dis-play Materialssupported by Shanghai Techni-cal Service Center of Science and Engineering Computing,Shanghai University and Hefei Advanced Computing Center.
文摘In past decades,ABX_(3) halide perovskites have attracted great interest in solar cells due to excellent opto-electronic properties,such as high carrier mobility.However,instability and toxicity are obstacles on the commercial route for perovskites.Many studies have turned to exploring A_(2) BX_(6) and A_(3) B_(2) X_(9) for better stability.Unfortunately,the carrier mobilities of these two types are inferior to ABX_(3),lower by an order of magnitude.Furthermore,the mobility of ABX_(3) is distributed over a large range of 1.78-4500 cm^(2) V^(−1) s^(−1) in experiments,which contributes to another diversity of mobilities.In this paper,we aim at reveal-ing the physical origin of the above-mentioned diversities by theoretical studies on CsBX_(3),Cs_(2) BX_(6),and Cs_(3) B_(2) X_(9)(B=Sn,Pb,Sb,Bi,X=Br,Cl).The difference in group velocities is the major reason responsible for the variation in these types.The unique three-dimensional connected conductive network of CsBX_(3) determines its large group velocity.As for carrier scattering,ionized impurity scattering dominates at low carrier and high ionized impurity concentrations.Detailed analysis reveals that band degeneracy is strongly related to the impurity scattering rate,while dielectric constant is almost immune.Our study provides a better understanding of the relationship between electronic structures and mobilities for po-tential applications in photovoltaics.
