Chirality,a common phenomenon in nature,appears in structures ranging from galaxies and condensed matter to atomic nuclei.There is a persistent demand for new,high-precision methods to detect chiral structures,particu...Chirality,a common phenomenon in nature,appears in structures ranging from galaxies and condensed matter to atomic nuclei.There is a persistent demand for new,high-precision methods to detect chiral structures,particularly at the microscale.Here,we propose a novel method,vortex Mössbauer spectroscopy,for probing chiral structures.By leveraging the orbital angular momentum carried by vortex beams,this approach achieves high precision in detecting chiral structures at scales ranging from nanometers to hundreds of nanometers.Our simulation shows the ratio of characteristic lines in the Mössbauer spectra of ^(57)Fe under vortex beams exhibits differences of up to four orders of magnitude for atomic structures with different arrangements.Additionally,simulations reveal the response of ^(229m)Th chiral structures to vortex beams with opposite angular momenta differs by approximately 49-fold.These significant spectral variations indicate that this new vortex Mössbauer probe holds great potential for investigating the microscopic chiral structures and interactions of matter.展开更多
During the hyperacute phase of intracerebral hemorrhage(ICH),the mass effect and blood components mechanically lead to brain damage and neurotoxicity.Our findings revealed that the mass effect and transferrin precipit...During the hyperacute phase of intracerebral hemorrhage(ICH),the mass effect and blood components mechanically lead to brain damage and neurotoxicity.Our findings revealed that the mass effect and transferrin precipitate neuronal oxidative stress and iron uptake,culminating in ferroptosis in neurons.M6A(N6-methyladenosine)modification,the most prevalent mRNA modification,plays a critical role in various cell death pathways.The Fto(fat mass and obesity-associated protein)demethylase has been implicated in numerous signaling pathways of neurological diseases by modulating m6A mRNA levels.Regulation of Fto protein levels in neurons effectively mitigated mass effect-induced neuronal ferroptosis.Applying nanopore direct RNA sequencing,we identified voltage-dependent anion channel 3(Vdac3)as a potential target associated with ferroptosis.Fto influenced neuronal ferroptosis by regulating the m6A methylation of Vdac3 mRNA.These findings elucidate the intricate interplay between Fto,Vdac3,m6A methylation,and ferroptosis in neurons during the hyperacute phase post-ICH and suggest novel therapeutic strategies for ICH.展开更多
Introduction:Surgeons typically prefer 270μm and 272μm laser probes in retrograde intrarenal surgery(RIRS)due to the reduced deflection capacity of flexible ureterorenoscopes when using larger probe diameters.This s...Introduction:Surgeons typically prefer 270μm and 272μm laser probes in retrograde intrarenal surgery(RIRS)due to the reduced deflection capacity of flexible ureterorenoscopes when using larger probe diameters.This study aims to investigate the effects of 272 and 365μm holmium laser probes on operative time,clinical efficacy,and complication rates in RIRS.Materials and Methods:A total of 285 patients with proximal ureteral or kidney stones who met the inclusion criteria were enrolled in the study.Patients were divided into two groups based on laser probe thickness:272μm and 365μm.Stone-free rates,operative time,and complication rates were compared between the groups.Factors affecting stone-free rates were analyzed using multivariate logistic regression analysis.Results:Patient and stone characteristics were similar between the two groups.No significant differences were found in stone-free or complication rates.However,operative time was significantly shorter in the 365μm probe group.In univariate analysis,risk factors for postoperative residual stones included multi-calyceal stones,lower pole stones,high Hounsfield unit(HU)values on noncontrast computed tomography,and larger stone size.In multivariate analysis,independent prognostic factors for residual stones were identified as multi-calycal stones,lower pole stones,and high HU values.Conclusion:Compared to 272μm laser probes,operative time was shorter in surgeries performed with 365μm laser probes.The 365μm holmium laser can be effectively and safely used in the treatment of proximal ureteral and renal stones,demonstrating high clinical efficacy and safety.展开更多
In 2018,Baige,Xizang,witnessed two consecutive large-scale landslides,causing significant damage and drawing widespread attention.From March 2011 to February 2018,the Baige landslide exhibited a 50-m displacement with...In 2018,Baige,Xizang,witnessed two consecutive large-scale landslides,causing significant damage and drawing widespread attention.From March 2011 to February 2018,the Baige landslide exhibited a 50-m displacement without complete failure,culminating in a collapse in October 2018.The mechanisms behind its resistance to failure despite substantial deformation and the influence of the complex geo-structure within the tectonic mélange belt remain unclear.To address these questions,this study utilized a multidisciplinary approach,integrating on-site geological field mapping,surface deformation monitoring,multielectrode resistivity method,and deep displacement analysis.The aim was to evaluate the impact of the intricate geo-structure within the tectonic mélange belt on the Baige landslide events.Findings reveal that the landslide's geo-structure consists of structurally fractured,mesh-like rock masses,including heterogeneous lenticular rock masses and intermittent brittle shear zones distributed around the lens-shaped rock masses.The study underscores that the inhomogeneous and weakly deformed lenticular rock masses function as natural locked segments,governing the stability of the Baige landslide.Specifically,the relatively intact and hard granodiorite porphyry play a crucial role in locking the landslide's deformation.Deep displacement analysis indicates that the brittle shear zones act as the sliding surfaces.The progressive destruction of the locked segments and the gradual penetration of brittle shear zones,driven by gravitational potential energy,contribute to the landslide occurrence.This research provides critical insights into the formation mechanisms of large-scale landslides within tectonic mélange belts.展开更多
Ball milling for long time （such as 10, 20, and 30 h） can transform Fe84.94Si9,68A15.38 alloy powders with irregular shapes into flakes. X-ray diffraction （XRD） and M6ssbauer measurements have proven that the unmi...Ball milling for long time （such as 10, 20, and 30 h） can transform Fe84.94Si9,68A15.38 alloy powders with irregular shapes into flakes. X-ray diffraction （XRD） and M6ssbauer measurements have proven that the unmilled particles and the flakes obtained by milling for 10 h have the same D03-type superlattice structure. The flakes obtained by milling for 20 h and 30 h have the same disorder a-Fe（Si, A1） structure. There are more than 6 absorption peaks in the transmis- sion MSssbauer spectra （TMSs） for the particles with D03-type superlattice structure, which can be fitted with 5 sextets representing 5 different Fe-site environments. However, only 6 TMS absorption peaks have been found for particles with a disorder a-Fe（Si, A1） structure, which can be fitted with the distributions of M6ssbauer parameters （Bhf, isomer shift）. The TMS results show that the flaky particles have a stronger tendency to possess the planar magnetic anisotropy. As the result, the flakes have larger microwave permeability values than particles with irregular shapes. The conversion electron M6ssbauer spectra （CEMSs） also show the significantly different Fe-sites environments between the alloy surface and the inside.展开更多
Ultrafine particles prepared by evaporating pure Fe in CH4 atmosphere using arc-dischargeheating method, were found to consist of Fe-C solid solution, γ-Fe and Fe3C phases. EfFect of annealing temperature on phase tr...Ultrafine particles prepared by evaporating pure Fe in CH4 atmosphere using arc-dischargeheating method, were found to consist of Fe-C solid solution, γ-Fe and Fe3C phases. EfFect of annealing temperature on phase transformation and hyperfine interactions has been investigated by Mossbauer spectroscopy, X-ray diffraction (XRD), differential thermal analysis and thermogravimetry (DTA-TG), transmission electron microscopy (TEM), oxygen determination and vibrating sample magnetometer (VSM) measurements. It was observed that phase transformation of γ-Fe to α-Fe occurs during annealing in vacuum. The mechanism causing the change of hyperfine interactions with annealing temperature differs for Fe-C solution and interstitial compounds. DifFerence of hyperfine interactions of Fe-C solid solution in the starting sample and its annealed samples is ascribed to the improvement of activation of interstitial carbon atoms. Stress-relieving in structure of annealed Fe3C particle can result in a weak influence on hyperfine interactions. Parameters fitted to the Mossbauer spectra show the existence of superparamagnetism in all the samples. Absorbed and combined oxygen on particle surface of the starting sample were determined.展开更多
Dispatched by the Chinese government,a multidisciplinary team of 30 researchers collaborated with a team from Myanmar to conduct a 14-day on-site investigation.The work encompassed seismic intensity assessments,field ...Dispatched by the Chinese government,a multidisciplinary team of 30 researchers collaborated with a team from Myanmar to conduct a 14-day on-site investigation.The work encompassed seismic intensity assessments,field surveys,and loss evaluations.The paper focuses on the intensity distribution and structural damage characteristics of the 2025 M7.9 Myanmar earthquake,yielding the following key findings.(1)The seismogenic fault rupture propagated in a nearly N-S direction,with a surface rupture length of approximately 450 km.The seismic impact zone exhibited an elongated N-S distribution and a shorter E-W span,distributed like a belt around the seismogenic fault.(2)Within the seismic impact zones,existing buildings comprised five primary structural types,with timber(bamboo)structures constituting the largest proportion(≈80%in rural areas,≈50%in urban areas).The relatively low disaster losses and casualties were primarily attributable to the good seismic performance and low damage ratio of timber(bamboo)structures across varying intensity zones.(3)An anomalous zone of intensityⅨwas located at the boundary between intensityⅥandⅦregions in Nay Pyi Taw.Here,ridge topography combined with soft soil layers significantly amplified ground motion,exacerbating structural damage.(4)Directional effects of ground motion were observed,with the structural damage phenomena and peak ground acceleration(PGA)values in the N-S direction exceeding those in the E-W direction.This validates that the maximum PGA distribution of strike-slip fault earthquakes aligns with the fault strike.The research is expected to provide technical support for post-disaster reconstruction planning,site selection,and disaster mitigation strategies in Myanmar.展开更多
In this paper, an overview of the theory of Mössbauer effect is covered, and the main hyperfine interactions parameters which affect the shape of the resultant Mössbauer spectrum are explained and il...In this paper, an overview of the theory of Mössbauer effect is covered, and the main hyperfine interactions parameters which affect the shape of the resultant Mössbauer spectrum are explained and illustrated as well. In principle, Mössbauer effect applies to any and all nuclides, but in practice, certain ideal properties are desirable;that is, the conditions for recoil-free emission and absorption of gamma rays must be optimized. Therefore, briefly discussed in this review, one of the most commonly used for practical and fundamental studies the 151Eu Mössbauer isotope. Also, the intermediate valence phenomena and their theoretical treatments are briefly discussed.展开更多
The release of phosphorus(P)from anaerobic sediments becomes the dominant source of P loading with effective control of external P pollution.As a crucial component responsible for binding P,vivianite(Fe_(3)(PO_(4))_(2...The release of phosphorus(P)from anaerobic sediments becomes the dominant source of P loading with effective control of external P pollution.As a crucial component responsible for binding P,vivianite(Fe_(3)(PO_(4))_(2)·8H_(2)O)in sediment inevitably impacts the P level and transformation.The release of P from vivianite mediated by sulphide was investigated using simulated overlying watersediment and chemical reaction systems.The percentage of redox-stable P in the sediments increased with vivianite input in the overlying watersediment system.Increasing P concentrations in both the overlying water and interstitial water occurred before day 10,accompanied by a decreasing percentage of redox-sensitive P in the sediments driven by sulphide.The continuous release of P from vivianite clarifies the influence of sulphide on promoting vivianite dissolution in a chemical reaction system with vivianite and sulphide solution.Additionally,Mössbauer spectrum and nanoscale secondary ionmass spectrometry(NanoSIMS)images based on the chemical reaction with^(57)Fe isotope labelling demonstrated the presence of initial vivianite,newly produced vivianite,and FeS_(2).展开更多
The solid state solutions of europium transition element oxides Eu (Fe0.8M0.2)O3 (M=Sc, Cr, Mn, Co) are synthesized. The X-ray diffraction of the compound shows that all the compounds possess the perovskite structures...The solid state solutions of europium transition element oxides Eu (Fe0.8M0.2)O3 (M=Sc, Cr, Mn, Co) are synthesized. The X-ray diffraction of the compound shows that all the compounds possess the perovskite structures. Both the 151Eu Mossbauer spectra and the Fe Mossbauer spectra are measured. The hyperfine magnetic field and non-axisymmetric electric field gradient are observed in the Eu Mossbauer spectrum. The 57Fe Mossbauer spectrum shows that there are four components of hyperfine fields corresponding to four kinds of different neighbours of the Fe ion.展开更多
This study determined the lifetime of the first excited state(5∕2_(1)^(+))in ^(139)La via β-γ time-difference measurement using a LaBr_(3)+plastic scintillator array.This state is populated following the decay of ^...This study determined the lifetime of the first excited state(5∕2_(1)^(+))in ^(139)La via β-γ time-difference measurement using a LaBr_(3)+plastic scintillator array.This state is populated following the decay of ^(139)Ba produced in the^(138)Ba(n,γ)reaction.Compared with previous experiments using only stilbene/plastic crystals,this experiment separates the background contribution in the γ-ray spectrum owing to the high energy resolution of LaBr_(3).The L-forbidden M1 transition strength,B(M1,5∕2_(1)^(+)→7∕2_(1)^(+)),in^(139)La was measured and compared with detailed large-scale shell model calculations,with a special focus on the core-excitation effect.The results showed the importance of both proton and neutron core-excitations in explaining the M1 transition strength.Meanwhile,the effective g-factor for the tensor term of the M1 operator was smaller than the previously reported value in this region or around ^(208)Pb.展开更多
We study the lensing phenomena of the strong gravity regime of five-dimensional charged,equally rotating black holes with a cosmological constant,familiarly known as the Cvetic–Lu–Pope(CLP)black holes.These black ho...We study the lensing phenomena of the strong gravity regime of five-dimensional charged,equally rotating black holes with a cosmological constant,familiarly known as the Cvetic–Lu–Pope(CLP)black holes.These black holes are characterized by three observable parameters,the mass M,the charge Q and the angular momentum J,in addition to the cosmological constant.We investigate the strong gravitational lensing observables,mainly the photon sphere radius,the minimum impact parameter,the deflection angle,the angular size,and the magnification of the relativistic images.We model the M87 and SgrA*for these observables.We also focus on the relativistic time delay effect in the strong-field regime of gravity and the impact of the observable on it.The analytical expressions for the observables of the relativistic images with vanishing angular momentum(j=0)are discussed in some detail.We shed a light on the gravitational time delay effect by incorporating the lensing observables.The gravitational time delay has a direct consequence on the photon sphere radius and hence on the quasinormal modes.展开更多
采用机械合金化法制备Al V Fe纳米粉末 ,通过测定M ssbauer效应 ,研究了不同球磨能量对制备Al V Fe纳米粉末的影响·结果表明 ,振动球磨与高能球磨所制备的Al V Fe纳米粉末结构均由非晶和α Al纳米晶组成 ,其非晶含量随着球磨能量...采用机械合金化法制备Al V Fe纳米粉末 ,通过测定M ssbauer效应 ,研究了不同球磨能量对制备Al V Fe纳米粉末的影响·结果表明 ,振动球磨与高能球磨所制备的Al V Fe纳米粉末结构均由非晶和α Al纳米晶组成 ,其非晶含量随着球磨能量的增加而有所不同·展开更多
基金supported in part by the National Key R&D Program(Grant No.2023YFA1606900)the National Natural Science Foundation of China(Grant No.12235003)。
文摘Chirality,a common phenomenon in nature,appears in structures ranging from galaxies and condensed matter to atomic nuclei.There is a persistent demand for new,high-precision methods to detect chiral structures,particularly at the microscale.Here,we propose a novel method,vortex Mössbauer spectroscopy,for probing chiral structures.By leveraging the orbital angular momentum carried by vortex beams,this approach achieves high precision in detecting chiral structures at scales ranging from nanometers to hundreds of nanometers.Our simulation shows the ratio of characteristic lines in the Mössbauer spectra of ^(57)Fe under vortex beams exhibits differences of up to four orders of magnitude for atomic structures with different arrangements.Additionally,simulations reveal the response of ^(229m)Th chiral structures to vortex beams with opposite angular momenta differs by approximately 49-fold.These significant spectral variations indicate that this new vortex Mössbauer probe holds great potential for investigating the microscopic chiral structures and interactions of matter.
基金supported by the National Key R&D Program of China(2022YFE0131000)the National Natural Science Foundation of China(82220108012,82271306,and 82071307)+1 种基金The Science and Education for Health Foundation of Suzhou for Youth(KJXW2023001)the Boxi Youth Natural Science Foundation(BXQN2023028).
文摘During the hyperacute phase of intracerebral hemorrhage(ICH),the mass effect and blood components mechanically lead to brain damage and neurotoxicity.Our findings revealed that the mass effect and transferrin precipitate neuronal oxidative stress and iron uptake,culminating in ferroptosis in neurons.M6A(N6-methyladenosine)modification,the most prevalent mRNA modification,plays a critical role in various cell death pathways.The Fto(fat mass and obesity-associated protein)demethylase has been implicated in numerous signaling pathways of neurological diseases by modulating m6A mRNA levels.Regulation of Fto protein levels in neurons effectively mitigated mass effect-induced neuronal ferroptosis.Applying nanopore direct RNA sequencing,we identified voltage-dependent anion channel 3(Vdac3)as a potential target associated with ferroptosis.Fto influenced neuronal ferroptosis by regulating the m6A methylation of Vdac3 mRNA.These findings elucidate the intricate interplay between Fto,Vdac3,m6A methylation,and ferroptosis in neurons during the hyperacute phase post-ICH and suggest novel therapeutic strategies for ICH.
文摘Introduction:Surgeons typically prefer 270μm and 272μm laser probes in retrograde intrarenal surgery(RIRS)due to the reduced deflection capacity of flexible ureterorenoscopes when using larger probe diameters.This study aims to investigate the effects of 272 and 365μm holmium laser probes on operative time,clinical efficacy,and complication rates in RIRS.Materials and Methods:A total of 285 patients with proximal ureteral or kidney stones who met the inclusion criteria were enrolled in the study.Patients were divided into two groups based on laser probe thickness:272μm and 365μm.Stone-free rates,operative time,and complication rates were compared between the groups.Factors affecting stone-free rates were analyzed using multivariate logistic regression analysis.Results:Patient and stone characteristics were similar between the two groups.No significant differences were found in stone-free or complication rates.However,operative time was significantly shorter in the 365μm probe group.In univariate analysis,risk factors for postoperative residual stones included multi-calyceal stones,lower pole stones,high Hounsfield unit(HU)values on noncontrast computed tomography,and larger stone size.In multivariate analysis,independent prognostic factors for residual stones were identified as multi-calycal stones,lower pole stones,and high HU values.Conclusion:Compared to 272μm laser probes,operative time was shorter in surgeries performed with 365μm laser probes.The 365μm holmium laser can be effectively and safely used in the treatment of proximal ureteral and renal stones,demonstrating high clinical efficacy and safety.
基金supported by the National Major Scientific Instruments and Equipment Development Projects of China(No.41827808)the Major Program of the National Natural Science Foundation of China(No.42090055)Supported by Science and Technology Projects of Xizang Autonomous Region,China(No.XZ202402ZD0001)。
文摘In 2018,Baige,Xizang,witnessed two consecutive large-scale landslides,causing significant damage and drawing widespread attention.From March 2011 to February 2018,the Baige landslide exhibited a 50-m displacement without complete failure,culminating in a collapse in October 2018.The mechanisms behind its resistance to failure despite substantial deformation and the influence of the complex geo-structure within the tectonic mélange belt remain unclear.To address these questions,this study utilized a multidisciplinary approach,integrating on-site geological field mapping,surface deformation monitoring,multielectrode resistivity method,and deep displacement analysis.The aim was to evaluate the impact of the intricate geo-structure within the tectonic mélange belt on the Baige landslide events.Findings reveal that the landslide's geo-structure consists of structurally fractured,mesh-like rock masses,including heterogeneous lenticular rock masses and intermittent brittle shear zones distributed around the lens-shaped rock masses.The study underscores that the inhomogeneous and weakly deformed lenticular rock masses function as natural locked segments,governing the stability of the Baige landslide.Specifically,the relatively intact and hard granodiorite porphyry play a crucial role in locking the landslide's deformation.Deep displacement analysis indicates that the brittle shear zones act as the sliding surfaces.The progressive destruction of the locked segments and the gradual penetration of brittle shear zones,driven by gravitational potential energy,contribute to the landslide occurrence.This research provides critical insights into the formation mechanisms of large-scale landslides within tectonic mélange belts.
基金supported by the National Key Basic Research Program of China(Grant No.2010CB334702)the China National Funds for Distinguished Young Scientists(Grant No.51025208)+1 种基金the International Collaboration Project of Sichuan Province,China(Grant Nos.2011HH0001 and 2012JQ0053)the Program for New Century Excellent Talents in Universities,China(Grant No.NCET-11-0060)
文摘Ball milling for long time （such as 10, 20, and 30 h） can transform Fe84.94Si9,68A15.38 alloy powders with irregular shapes into flakes. X-ray diffraction （XRD） and M6ssbauer measurements have proven that the unmilled particles and the flakes obtained by milling for 10 h have the same D03-type superlattice structure. The flakes obtained by milling for 20 h and 30 h have the same disorder a-Fe（Si, A1） structure. There are more than 6 absorption peaks in the transmis- sion MSssbauer spectra （TMSs） for the particles with D03-type superlattice structure, which can be fitted with 5 sextets representing 5 different Fe-site environments. However, only 6 TMS absorption peaks have been found for particles with a disorder a-Fe（Si, A1） structure, which can be fitted with the distributions of M6ssbauer parameters （Bhf, isomer shift）. The TMS results show that the flaky particles have a stronger tendency to possess the planar magnetic anisotropy. As the result, the flakes have larger microwave permeability values than particles with irregular shapes. The conversion electron M6ssbauer spectra （CEMSs） also show the significantly different Fe-sites environments between the alloy surface and the inside.
文摘Ultrafine particles prepared by evaporating pure Fe in CH4 atmosphere using arc-dischargeheating method, were found to consist of Fe-C solid solution, γ-Fe and Fe3C phases. EfFect of annealing temperature on phase transformation and hyperfine interactions has been investigated by Mossbauer spectroscopy, X-ray diffraction (XRD), differential thermal analysis and thermogravimetry (DTA-TG), transmission electron microscopy (TEM), oxygen determination and vibrating sample magnetometer (VSM) measurements. It was observed that phase transformation of γ-Fe to α-Fe occurs during annealing in vacuum. The mechanism causing the change of hyperfine interactions with annealing temperature differs for Fe-C solution and interstitial compounds. DifFerence of hyperfine interactions of Fe-C solid solution in the starting sample and its annealed samples is ascribed to the improvement of activation of interstitial carbon atoms. Stress-relieving in structure of annealed Fe3C particle can result in a weak influence on hyperfine interactions. Parameters fitted to the Mossbauer spectra show the existence of superparamagnetism in all the samples. Absorbed and combined oxygen on particle surface of the starting sample were determined.
基金National Natural Science Foundation of China under Grant No.U2239252National Natural Science Foundation of China under Grant No.52279128Natural Science Foundation of Heilongjiang Province of China under Grant No.YQ2022E013。
文摘Dispatched by the Chinese government,a multidisciplinary team of 30 researchers collaborated with a team from Myanmar to conduct a 14-day on-site investigation.The work encompassed seismic intensity assessments,field surveys,and loss evaluations.The paper focuses on the intensity distribution and structural damage characteristics of the 2025 M7.9 Myanmar earthquake,yielding the following key findings.(1)The seismogenic fault rupture propagated in a nearly N-S direction,with a surface rupture length of approximately 450 km.The seismic impact zone exhibited an elongated N-S distribution and a shorter E-W span,distributed like a belt around the seismogenic fault.(2)Within the seismic impact zones,existing buildings comprised five primary structural types,with timber(bamboo)structures constituting the largest proportion(≈80%in rural areas,≈50%in urban areas).The relatively low disaster losses and casualties were primarily attributable to the good seismic performance and low damage ratio of timber(bamboo)structures across varying intensity zones.(3)An anomalous zone of intensityⅨwas located at the boundary between intensityⅥandⅦregions in Nay Pyi Taw.Here,ridge topography combined with soft soil layers significantly amplified ground motion,exacerbating structural damage.(4)Directional effects of ground motion were observed,with the structural damage phenomena and peak ground acceleration(PGA)values in the N-S direction exceeding those in the E-W direction.This validates that the maximum PGA distribution of strike-slip fault earthquakes aligns with the fault strike.The research is expected to provide technical support for post-disaster reconstruction planning,site selection,and disaster mitigation strategies in Myanmar.
文摘In this paper, an overview of the theory of Mössbauer effect is covered, and the main hyperfine interactions parameters which affect the shape of the resultant Mössbauer spectrum are explained and illustrated as well. In principle, Mössbauer effect applies to any and all nuclides, but in practice, certain ideal properties are desirable;that is, the conditions for recoil-free emission and absorption of gamma rays must be optimized. Therefore, briefly discussed in this review, one of the most commonly used for practical and fundamental studies the 151Eu Mössbauer isotope. Also, the intermediate valence phenomena and their theoretical treatments are briefly discussed.
基金supported by the National Natural Science Foundation of China(No.42177059).
文摘The release of phosphorus(P)from anaerobic sediments becomes the dominant source of P loading with effective control of external P pollution.As a crucial component responsible for binding P,vivianite(Fe_(3)(PO_(4))_(2)·8H_(2)O)in sediment inevitably impacts the P level and transformation.The release of P from vivianite mediated by sulphide was investigated using simulated overlying watersediment and chemical reaction systems.The percentage of redox-stable P in the sediments increased with vivianite input in the overlying watersediment system.Increasing P concentrations in both the overlying water and interstitial water occurred before day 10,accompanied by a decreasing percentage of redox-sensitive P in the sediments driven by sulphide.The continuous release of P from vivianite clarifies the influence of sulphide on promoting vivianite dissolution in a chemical reaction system with vivianite and sulphide solution.Additionally,Mössbauer spectrum and nanoscale secondary ionmass spectrometry(NanoSIMS)images based on the chemical reaction with^(57)Fe isotope labelling demonstrated the presence of initial vivianite,newly produced vivianite,and FeS_(2).
文摘The solid state solutions of europium transition element oxides Eu (Fe0.8M0.2)O3 (M=Sc, Cr, Mn, Co) are synthesized. The X-ray diffraction of the compound shows that all the compounds possess the perovskite structures. Both the 151Eu Mossbauer spectra and the Fe Mossbauer spectra are measured. The hyperfine magnetic field and non-axisymmetric electric field gradient are observed in the Eu Mossbauer spectrum. The 57Fe Mossbauer spectrum shows that there are four components of hyperfine fields corresponding to four kinds of different neighbours of the Fe ion.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research (No. 2021B0301030006)Young Scientists Fund of the National Natural Science Foundation of China (No. 12405144)+3 种基金the National Natural Science Foundation of China (No. 12475129)the International Atomic Energy Agency Coordinatated Research Project F41034 (No. 28649)the computational resources from Sun Yat-sen University the National Supercomputer Center in Guangzhouthe Natural Science Foundation of Guangdong Province,China (No. 2025A1515012112)
文摘This study determined the lifetime of the first excited state(5∕2_(1)^(+))in ^(139)La via β-γ time-difference measurement using a LaBr_(3)+plastic scintillator array.This state is populated following the decay of ^(139)Ba produced in the^(138)Ba(n,γ)reaction.Compared with previous experiments using only stilbene/plastic crystals,this experiment separates the background contribution in the γ-ray spectrum owing to the high energy resolution of LaBr_(3).The L-forbidden M1 transition strength,B(M1,5∕2_(1)^(+)→7∕2_(1)^(+)),in^(139)La was measured and compared with detailed large-scale shell model calculations,with a special focus on the core-excitation effect.The results showed the importance of both proton and neutron core-excitations in explaining the M1 transition strength.Meanwhile,the effective g-factor for the tensor term of the M1 operator was smaller than the previously reported value in this region or around ^(208)Pb.
基金supported by the National Natural Science Foundation of China under Grants Nos.12475056,12347177,and 12247101,the 111 Project under Grant No.B20063Lanzhou City's scientific research funding subsidy to Lanzhou Universitythe Gansu Province Major Scientific and Technological Special Project。
文摘We study the lensing phenomena of the strong gravity regime of five-dimensional charged,equally rotating black holes with a cosmological constant,familiarly known as the Cvetic–Lu–Pope(CLP)black holes.These black holes are characterized by three observable parameters,the mass M,the charge Q and the angular momentum J,in addition to the cosmological constant.We investigate the strong gravitational lensing observables,mainly the photon sphere radius,the minimum impact parameter,the deflection angle,the angular size,and the magnification of the relativistic images.We model the M87 and SgrA*for these observables.We also focus on the relativistic time delay effect in the strong-field regime of gravity and the impact of the observable on it.The analytical expressions for the observables of the relativistic images with vanishing angular momentum(j=0)are discussed in some detail.We shed a light on the gravitational time delay effect by incorporating the lensing observables.The gravitational time delay has a direct consequence on the photon sphere radius and hence on the quasinormal modes.
