The simultaneous measurement of the spatial profile and spectrum of laser-accelerated protons is important for further optimization of the beam qualities and applications.We report a detailed study regarding the under...The simultaneous measurement of the spatial profile and spectrum of laser-accelerated protons is important for further optimization of the beam qualities and applications.We report a detailed study regarding the underlying physics and regular procedure of such a measurement through the radioactivation of a stack composed of aluminum,copper,and CR-39 plates as well as radiochromic films(RCFs).After being radioactivated,the copper plates are placed on imaging plates(IPs)to detect the positrons emitted by the reaction products through contact imaging.The spectrum and energy-dependent spatial profile of the protons are then obtained from the IPs and confirmed by the measured ones from the RCFs and CR-39 plates.We also discuss the detection range,influence of electrons,radiation safety,and spatial resolution of this measurement.Finally,insights regarding the extension of the current method to online measurements and dynamic proton imaging are also provided.展开更多
The described structural model tries to answer some open questions such as: Why do quarks not exist in the open state? Where are the antiparticles from the Big Bang?
Nowadays,radiation engineering is a promising direction in the creation of semiconductor devices.The proton irradiation is used to controllably change the optical,electrical,recombination,mechanical and structural pro...Nowadays,radiation engineering is a promising direction in the creation of semiconductor devices.The proton irradiation is used to controllably change the optical,electrical,recombination,mechanical and structural properties of the semiconductors.Low-energy protons make it possible to purposefully change material properties near the surface where the n^(+)-p junction is located.In this paper,the impact of low-energy protons on the electro physical parameters of n+-p-p+silicon photoelectric converters(SPC)is analyzed.The current-voltage characteristics and switching time of these SPCs are measured.The switching time is determined using rectangular bipolar voltage pulses with an amplitude of 10 mV,a frequency of 200 kHz,or a frequency of 1 MHz.A theoretical and experimental analysis of the obtained results is performed.The comparison of experimental data with the results of calculations shows that protons with an energy of 180 keV and a dose of 10×15 cm^(-2) create two regions in the space charge region of the n^(+)-p junction with different switching times of 4.2×10^(-7) s and 5.5×10^(-8) s.SPC frequency characteristics have been improved by reducing the effective lifetime by 5-10 times.This effect can be used to create high-speed photodiodes with an operating modulation frequency of 18 MHz.展开更多
In this work, the mass stopping power and range of protons in biological human body tissues (ovary, lung and breast) were calculated at the energy ranging from 0.04 MeV to 200 MeV using the MATLAB Program. The data re...In this work, the mass stopping power and range of protons in biological human body tissues (ovary, lung and breast) were calculated at the energy ranging from 0.04 MeV to 200 MeV using the MATLAB Program. The data relating to the densities, average atomic number to mass number and excitation energy for the present tissues were collected from ICRU Report 46. The mass stopping power was calculated by the Bethe formula. Moreover, the simple integration (continuous slowing down approximation) method was employed for calculating protons range at the tissues. The results of the mass stopping power versus energy and the range versus energy were presented graphically and the empirical formulae for calculating the mass stopping power and the ranges were obtained. The present results for mass stopping powers and ranges were compared with the results obtained by others. Good agreements were found between them, especially at the energy ranging from 3 to 200 MeV.展开更多
In this work, the electronic mass stopping power and the range of protons in some biological human body parts (Water, Muscle, Skeletal and Bone, Cortical) were calculated in the energy range of protons 0.04 to 200 MeV...In this work, the electronic mass stopping power and the range of protons in some biological human body parts (Water, Muscle, Skeletal and Bone, Cortical) were calculated in the energy range of protons 0.04 to 200 MeV using the theory of Bethe-Bloch formula as giving in the references. All these calculations were done using Matlab program. The data related to the densities, average atomic number to mass number and excitation energies for the present tissues and substances were collected from ICRU Report 44 (1989). The present results for electronic mass stopping powers and ranges were compared with the data of PSTAR and good agreements were found between them, especially at energies between 1 - 200 MeV for stopping power and 4 - 200 MeV for the range. Also in this study, several important quantities in the field of radiation, such as thickness, linear energy transfer (LET), absorbed dose, equivalent dose, and effective dose of the protons in the given biological human body parts were calculated at protons energy 0.04 - 200 MeV.展开更多
Based on the participant-spectator model and the analysis of particle producing proce-ss, the rapidity distribution and the noninvariant center-of-mass energy spectrum of final pro-tons produced in inelastic nucleus-n...Based on the participant-spectator model and the analysis of particle producing proce-ss, the rapidity distribution and the noninvariant center-of-mass energy spectrum of final pro-tons produced in inelastic nucleus-nucleus collisions are studied.展开更多
Scaling down of semiconductor encounters varieties of technical challenges such as Vth variation, critical charge. It is shown that circuits have scaled to the point that now even low-energy protons(LEPs) can cause si...Scaling down of semiconductor encounters varieties of technical challenges such as Vth variation, critical charge. It is shown that circuits have scaled to the point that now even low-energy protons(LEPs) can cause single event upsets through direct ionization[1]. Some of studies predicted that proton direct ionization (PDI) would dominate the total SEE rate[2], thus we focus on this study.展开更多
Proton pump inhibitors(PPIs) represent a milestone in the treatment of acid-related diseases, and are the mainstay in preventing upper gastrointestinal bleeding in high-risk patients treated with nonsteroidal antiinfl...Proton pump inhibitors(PPIs) represent a milestone in the treatment of acid-related diseases, and are the mainstay in preventing upper gastrointestinal bleeding in high-risk patients treated with nonsteroidal antiinflammatory drugs(NSAIDs) or low-dose aspirin. However, this beneficial effect does not extend to the lower gastrointestinal tract. PPIs do not prevent NSAID or aspirin-associated lower gastrointestinal bleeding(LGB). PPIs may increase both small bowel injury related to NSAIDs and low-dose aspirin treatment and the risk of LGB. Recent studies suggested that altering intestinal microbiota by PPIs may be involved in the pathogenesis of NSAID-enteropathy. An increase in LGB hospitalization rates may occur more frequently in older patients with more comorbidities and are associated with high hospital resource utilization, longer hospitalization, and increased mortality. Preventive strategies for NSAID and aspirin-associated gastrointestinal bleeding should be directed toward preventing both upper and lower gastrointestinal damage. Future research should be directed toward identifying patients at low-risk for gastrointestinal events associated with the use of NSAIDs or aspirin to avoid inappropriate PPI prescribing. Alternatively, the efficacy of new pharmacologic strategies should be evaluated in high-risk groups, with the aim of reducing the risk of both upper and lower gastrointestinal bleeding in these patients.展开更多
Single-event effects(SEEs)induced by mediumenergy protons in a 28 nm system-on-chip(SoC)were investigated at the China Institute of Atomic Energy.An on-chip memory block was irradiated with 90 MeV and 70 MeV protons,r...Single-event effects(SEEs)induced by mediumenergy protons in a 28 nm system-on-chip(SoC)were investigated at the China Institute of Atomic Energy.An on-chip memory block was irradiated with 90 MeV and 70 MeV protons,respectively.Single-bit upset and multicell upset events were observed,and an uppermost number of nine upset cells were discovered in the 90 MeV proton irradiation test.The results indicate that the SEE sensitivities of the 28 nm SoC to the 90 MeV and 70 MeV protons were similar.Cosmic Ray Effects on Micro-Electronics Monte Carlo simulations were analyzed,and it demonstrates that protons can induce effects in a 28 nm SoC if their energies are greater than 1.4 MeV and that the lowest corresponding linear energy transfer was 0.142 MeV cm^2 mg^-1.The similarities and discrepancies of the SEEs induced by the 90 MeV and 70 MeV protons were analyzed.展开更多
Approximately 25%of patients diagnosed with pancreatic cancer present with non-metastatic resectable or borderline resectable disease.Unfortunately,the cure rate for these“curable”patients is only in the range of 20...Approximately 25%of patients diagnosed with pancreatic cancer present with non-metastatic resectable or borderline resectable disease.Unfortunately,the cure rate for these“curable”patients is only in the range of 20%.Local-regional failure rates may exceed 50%after margin-negative,node-negative pancreatectomy,but up to 80%of resections are associated with regional lymph node or margin positivity.While systemic drug therapy and chemotherapy may prevent or delay the appearance of distant metastases,it is unlikely to have a significant impact on local-regional disease control.Preoperative radiotherapy would represent a rational intervention to improve local-regional control.The barrier to preoperative radiotherapy is the concern that it could potentially complicate what is already a long and complicated operation.When the radiotherapy is delivered with X-rays(photons),the entire cylinder of the abdomen is irradiated;therefore,an operating surgeon may be reluctant to accept the associated risk of increased toxicity.When preoperative radiotherapy is delivered with protons,however,significant bowel and gastric tissue-sparing is achieved and clinical outcomes indicate that proton therapy does not increase the risk of operative complications nor extend the length of the procedure.展开更多
Most protons in the solar wind belong to one of two different populations,the less dense beam protons and the denser core protons.The beam protons,with a velocity of(1-2)V_(A)(V_(A)is the local Alfvén speed),alwa...Most protons in the solar wind belong to one of two different populations,the less dense beam protons and the denser core protons.The beam protons,with a velocity of(1-2)V_(A)(V_(A)is the local Alfvén speed),always drift relative to the core protons;this kind of distribution is unstable and stimulates several kinds of wave mode.In this study,using a 2 D hybrid simulation model,we find that the original right-handed elliptically polarized Alfvén waves become linearly polarized,and eventually become right-handed and circularly polarized.Given that linearly polarized waves are a superposition of left-handed and right-handed waves,cyclotron resonance in the right-handed/left-handed component heats beam/core protons perpendicularly.The resonance between beam protons and right-handed polarized waves is stronger when the beam relative density is lower,resulting in more dramatic perpendicular heating of beam protons,whereas the situation is reversed when the beam relative density is larger.展开更多
It was investigated how react molecular clusters in water, starch, bio-matrices, polymers and in quartz on gravitation radiation from planets. Gravitation radiation (GR) was found to influence the proton jumping in hy...It was investigated how react molecular clusters in water, starch, bio-matrices, polymers and in quartz on gravitation radiation from planets. Gravitation radiation (GR) was found to influence the proton jumping in hydrogen bonds that stabilize the cluster structure. There was given a method calculating parameters of GR as well as a mechanism of its resonance interaction with weak GR from molecular matter (WGR). WGR has been defined as the result of proton dissolving in vacuum connected with its simultaneous condensation in the nearest free space. Both dissolving and condensation proceed with super light velocity. The gravitation wave length has been determined experimentally and it depends on the planet masses (between Earth and Sun λ ≥ 62 km, between Earth and Milky Way center λ ≥ 330 km). GR has been characterized with super light velocity. After analyzing the Sun influence on water two forms of protons were found: in a condensed and dissolved state. A new model for the atomic nucleus has been suggested according to which the protons in the nucleus oscillate between condensed and dissolved state, where in the case of isotopes this state is partially destroyed. The models for H2 and Be shall be given. Electron orbitals in atoms and molecules were found to be caused by a stationary front of shock waves from condensing protons.展开更多
Ground simulation tests of proton irradiation for Kapton films were conducted using the space synthesis irradiating facility,in which the energy of protons was chosen as 90 keV,and the flux was 5.0×1011 cm-2·...Ground simulation tests of proton irradiation for Kapton films were conducted using the space synthesis irradiating facility,in which the energy of protons was chosen as 90 keV,and the flux was 5.0×1011 cm-2·s-1.After proton irradiation some bulges like fingers appears on the surface of Kapton and the surface roughness increases apparently.UV/Vis analysis demonstrates that the irradiation leads to the red shifting in the edge of optical absorption and a strong increase in absorbance in the visible region.X-ray photoelectron spectroscopy(XPS) analysis indicates that the enrichment of carbon atom due to the bond breaking and reconstruction during the irradiation results in the degradation of the optical properties.展开更多
The neutron yield in the12C(d,n)13N reaction and the proton yield in the12C(d,p)13C reaction have been measured using deuteron beams of energies 0.6-3 MeV.The deuteron beam is delivered from a 4-MeV electrostatic acce...The neutron yield in the12C(d,n)13N reaction and the proton yield in the12C(d,p)13C reaction have been measured using deuteron beams of energies 0.6-3 MeV.The deuteron beam is delivered from a 4-MeV electrostatic accelerator and bombarded on a thick carbon target.The neutrons are detected at 0°,24°,and 48°and the protons at135°in the laboratory frame.Further,the ratio of the neutron yield to the proton yield was calculated.This can be used to effectively recognize the resonances.The resonances are found at 1.4 MeV,1.7 MeV,and 2.5 MeV in the12C(d,p)13C reaction,and at 1.6 MeV and 2.7 MeV in the12C(d,n)13N reaction.The proposed method provides a way to reduce systematic uncertainty and helps confirm more resonances in compound nuclei.展开更多
Zirconium tritiated(ZrTx)is an alternative target material for deuteron-triton(D-T)reaction neutron generator.The isotopic replacement and microstructure evolution induced by hydrogen isotope implantation could signif...Zirconium tritiated(ZrTx)is an alternative target material for deuteron-triton(D-T)reaction neutron generator.The isotopic replacement and microstructure evolution induced by hydrogen isotope implantation could significantly affect the performance of the target film.In this work,the zirconium deuteride film deposited on Mo/Si substrate was implanted by 150 keV protons with fluence from 1×10^(16 ) to 1×10^(18 )protons/cm^(2).After implantation,the depth profiles of retained hydrogen(H)and deuterium(D)in these target films were analyzed by elastic recoil detection analysis(ERDA),and time of flight-secondary ion mass spectrometry(ToF-SIMS).Additionally,the microstructure evolution was also observed by x-ray diffraction(XRD)and scanning electron microscope(SEM).The D concentration in the ZrDx film decreased versus the proton implantation fluence.An analytical model was proposed to describe the hydrogen isotopic trapping and exchange as functions of incident protons fluence.Additionally,the XRD analysis revealed that no new phase was formed after proton implantation.Furthermore,circular flakings were observed on the ZrDx surface from SEM images at fluence up to 1×10^(18) protons/cm^(2),and this surface morphology was considered to associate with the hydrogen atoms congregation in Mo/Si boundary.展开更多
Analysis of solar-cell array panel (SAP) data from the Arase satellite orbiting in the inner magnetosphere showed a clear degradation of solar cells that could be attributed to trapped protons with energies greater th...Analysis of solar-cell array panel (SAP) data from the Arase satellite orbiting in the inner magnetosphere showed a clear degradation of solar cells that could be attributed to trapped protons with energies greater than 6 MeV. Proton fluence was determined based on variations in the open-circuit voltage (Voc) of the solar cells, which we compared with that expected based on various distribution models (AP8MAX, AP9 mean and CRRESPRO quiet) of trapped protons. We found a general agreement, confirming the major contribution of trapped protons to the degradation, as well as a slight difference in the fluence expected based on the model calculations. To minimize this difference, we slightly modified the models, and found that concentrating the energetic protons on the magnetic equator provided a better agreement. Our results indicate that >6 MeV protons also has the equatorial concentration as reported for >18 MeV protons from the Van Allen Probes observation, and are interpreted as two components of the trapped protons, i.e., those of solar energetic particle (SEP) origin have an anisotropic pitch-angle distribution and are confined near the magnetic equator.展开更多
Inspired by the recent near-threshold J/ψphotoproduction measurements,we discuss gluon gravitational form factors(GFFs)and internal properties of the proton.This work presents a complete analysis of the proton gluon ...Inspired by the recent near-threshold J/ψphotoproduction measurements,we discuss gluon gravitational form factors(GFFs)and internal properties of the proton.This work presents a complete analysis of the proton gluon GFFs connecting the gluon part of the energy-momentum tensor and the heavy quarkonium photoproduction.In particular,a global fitting of the J/ψdifferential and total cross section experimental data is used to determine the gluon GFFs as functions of the squared momentum transfer t.Combined with the quark contributions to the D-term form factor extracted from the deeply virtual Compton scattering experiment,the total D-term is obtained to investigate their applications in describing the proton mechanical properties.These studies provide a unique perspective on investigating the proton gluon GFFs and important information for enhancing QCD constraints on the gluon GFFs.展开更多
The target backsheath field acceleration mechanism is one of the main mechanisms of laser-driven proton acceleration(LDPA)and strongly depends on the comprehensive performance of the ultrashort ultra-intense lasers us...The target backsheath field acceleration mechanism is one of the main mechanisms of laser-driven proton acceleration(LDPA)and strongly depends on the comprehensive performance of the ultrashort ultra-intense lasers used as the driving sources.The successful use of the SG-II Peta-watt(SG-II PW)laser facility for LDPA and its applications in radiographic diagnoses have been manifested by the good performance of the SG-II PW facility.Recently,the SG-II PW laser facility has undergone extensive maintenance and a comprehensive technical upgrade in terms of the seed source,laser contrast and terminal focus.LDPA experiments were performed using the maintained SG-II PW laser beam,and the highest cutoff energy of the proton beam was obviously increased.Accordingly,a double-film target structure was used,and the maximum cutoff energy of the proton beam was up to 70 MeV.These results demonstrate that the comprehensive performance of the SG-II PW laser facility was improved significantly.展开更多
PrBa_(0.5)Sr_(0.5)Co_(1.5)Fe_(0.5)O_(5+δ)(PrBSCF) has attracted much research interest as a potential triple ionic and electronic conductor(TIEC) electrode for protonic ceramic fuel cells(PCFCs). The chemical formula...PrBa_(0.5)Sr_(0.5)Co_(1.5)Fe_(0.5)O_(5+δ)(PrBSCF) has attracted much research interest as a potential triple ionic and electronic conductor(TIEC) electrode for protonic ceramic fuel cells(PCFCs). The chemical formula for Pr BSCF is AA'B_(2)O_(5+δ), with Pr(A-site) and Ba/Sr(A'-site) alternately stacked along the c-axis. Due to these structural features, the bulk oxygen ion diffusivity is significantly enhanced through the disorder-free channels in the PrO layer;thus, the A site cations(lanthanide ions) play a pivotal role in determining the overall electrochemical properties of layered perovskites. Consequently, previous research has predominantly focused on the electrical properties and oxygen bulk/surface kinetics of Ln cation effects,whereas the hydration properties for PCFC systems remain unidentified. Here, we thoroughly examined the proton uptake behavior and thermodynamic parameters for the hydration reaction to conclusively determine the changes in the electrochemical performances depending on LnBa_(0.5)Sr_(0.5)Co_(1.5)Fe_(0.5)O_(5+δ)(LnBSCF,Ln=Pr, Nd, and Gd) cathodes. At 500 ℃, the quantitative proton concentration of PrBSCF was 2.04 mol% and progressively decreased as the Ln cation size decreased. Similarly, the Gibbs free energy indicated that less energy was required for the formation of protonic defects in the order of Pr BSCF < Nd BSCF < Gd BSCF. To elucidate the close relationship between hydration properties and electrochemical performances in LnBSCF cathodes, PCFC single cell measurements and analysis of the distribution of relaxation time were further investigated.展开更多
Radio frequency quadrupoles(RFQs),which are crucial components of proton injectors,significantly affect the performance of proton accelerator facilities.An RFQ with a high frequency of 714 MHz dedicated to compact pro...Radio frequency quadrupoles(RFQs),which are crucial components of proton injectors,significantly affect the performance of proton accelerator facilities.An RFQ with a high frequency of 714 MHz dedicated to compact proton injectors for medi-cal applications is designed in this study.The RFQ is designed to accelerate proton beams from 50 keV to 4 MeV within a short length of 2 m and can be matched closely with the downstream drift tube linac to capture more particles through a preliminary optimization.To develop an advanced RFQ,challenging techniques,including fabrication and tuning method,must be evaluated and verified using a prototype.An aluminium prototype is derived from the conceptual design of the RFQ and then redesigned to confirm the radio frequency performance,fabrication procedure,and feasibility of the tuning algorithm.Eventually,a new tuning algorithm based on the response matrix and least-squares method is developed,which yields favorable results based on the prototype,i.e.,the errors of the dipole and quadrupole components reduced to a low level after several tuning iterations.Benefiting from the conceptual design and techniques obtained from the prototype,the formal mechanical design of the 2-m RFQ is ready for the next manufacturing step.展开更多
基金supported by the Institute for Basic ScienceKorea under the project code IBS-R012-D1by the Ultrashort Quantum Beam Facility(UQBF)operation program(No.140011)through APRI,GIST。
文摘The simultaneous measurement of the spatial profile and spectrum of laser-accelerated protons is important for further optimization of the beam qualities and applications.We report a detailed study regarding the underlying physics and regular procedure of such a measurement through the radioactivation of a stack composed of aluminum,copper,and CR-39 plates as well as radiochromic films(RCFs).After being radioactivated,the copper plates are placed on imaging plates(IPs)to detect the positrons emitted by the reaction products through contact imaging.The spectrum and energy-dependent spatial profile of the protons are then obtained from the IPs and confirmed by the measured ones from the RCFs and CR-39 plates.We also discuss the detection range,influence of electrons,radiation safety,and spatial resolution of this measurement.Finally,insights regarding the extension of the current method to online measurements and dynamic proton imaging are also provided.
文摘The described structural model tries to answer some open questions such as: Why do quarks not exist in the open state? Where are the antiparticles from the Big Bang?
文摘Nowadays,radiation engineering is a promising direction in the creation of semiconductor devices.The proton irradiation is used to controllably change the optical,electrical,recombination,mechanical and structural properties of the semiconductors.Low-energy protons make it possible to purposefully change material properties near the surface where the n^(+)-p junction is located.In this paper,the impact of low-energy protons on the electro physical parameters of n+-p-p+silicon photoelectric converters(SPC)is analyzed.The current-voltage characteristics and switching time of these SPCs are measured.The switching time is determined using rectangular bipolar voltage pulses with an amplitude of 10 mV,a frequency of 200 kHz,or a frequency of 1 MHz.A theoretical and experimental analysis of the obtained results is performed.The comparison of experimental data with the results of calculations shows that protons with an energy of 180 keV and a dose of 10×15 cm^(-2) create two regions in the space charge region of the n^(+)-p junction with different switching times of 4.2×10^(-7) s and 5.5×10^(-8) s.SPC frequency characteristics have been improved by reducing the effective lifetime by 5-10 times.This effect can be used to create high-speed photodiodes with an operating modulation frequency of 18 MHz.
文摘In this work, the mass stopping power and range of protons in biological human body tissues (ovary, lung and breast) were calculated at the energy ranging from 0.04 MeV to 200 MeV using the MATLAB Program. The data relating to the densities, average atomic number to mass number and excitation energy for the present tissues were collected from ICRU Report 46. The mass stopping power was calculated by the Bethe formula. Moreover, the simple integration (continuous slowing down approximation) method was employed for calculating protons range at the tissues. The results of the mass stopping power versus energy and the range versus energy were presented graphically and the empirical formulae for calculating the mass stopping power and the ranges were obtained. The present results for mass stopping powers and ranges were compared with the results obtained by others. Good agreements were found between them, especially at the energy ranging from 3 to 200 MeV.
文摘In this work, the electronic mass stopping power and the range of protons in some biological human body parts (Water, Muscle, Skeletal and Bone, Cortical) were calculated in the energy range of protons 0.04 to 200 MeV using the theory of Bethe-Bloch formula as giving in the references. All these calculations were done using Matlab program. The data related to the densities, average atomic number to mass number and excitation energies for the present tissues and substances were collected from ICRU Report 44 (1989). The present results for electronic mass stopping powers and ranges were compared with the data of PSTAR and good agreements were found between them, especially at energies between 1 - 200 MeV for stopping power and 4 - 200 MeV for the range. Also in this study, several important quantities in the field of radiation, such as thickness, linear energy transfer (LET), absorbed dose, equivalent dose, and effective dose of the protons in the given biological human body parts were calculated at protons energy 0.04 - 200 MeV.
文摘Based on the participant-spectator model and the analysis of particle producing proce-ss, the rapidity distribution and the noninvariant center-of-mass energy spectrum of final pro-tons produced in inelastic nucleus-nucleus collisions are studied.
文摘Scaling down of semiconductor encounters varieties of technical challenges such as Vth variation, critical charge. It is shown that circuits have scaled to the point that now even low-energy protons(LEPs) can cause single event upsets through direct ionization[1]. Some of studies predicted that proton direct ionization (PDI) would dominate the total SEE rate[2], thus we focus on this study.
文摘Proton pump inhibitors(PPIs) represent a milestone in the treatment of acid-related diseases, and are the mainstay in preventing upper gastrointestinal bleeding in high-risk patients treated with nonsteroidal antiinflammatory drugs(NSAIDs) or low-dose aspirin. However, this beneficial effect does not extend to the lower gastrointestinal tract. PPIs do not prevent NSAID or aspirin-associated lower gastrointestinal bleeding(LGB). PPIs may increase both small bowel injury related to NSAIDs and low-dose aspirin treatment and the risk of LGB. Recent studies suggested that altering intestinal microbiota by PPIs may be involved in the pathogenesis of NSAID-enteropathy. An increase in LGB hospitalization rates may occur more frequently in older patients with more comorbidities and are associated with high hospital resource utilization, longer hospitalization, and increased mortality. Preventive strategies for NSAID and aspirin-associated gastrointestinal bleeding should be directed toward preventing both upper and lower gastrointestinal damage. Future research should be directed toward identifying patients at low-risk for gastrointestinal events associated with the use of NSAIDs or aspirin to avoid inappropriate PPI prescribing. Alternatively, the efficacy of new pharmacologic strategies should be evaluated in high-risk groups, with the aim of reducing the risk of both upper and lower gastrointestinal bleeding in these patients.
基金supported by the National Natural Science Foundation of China(Grant Nos.11575138,11835006,11690040,and 11690043)
文摘Single-event effects(SEEs)induced by mediumenergy protons in a 28 nm system-on-chip(SoC)were investigated at the China Institute of Atomic Energy.An on-chip memory block was irradiated with 90 MeV and 70 MeV protons,respectively.Single-bit upset and multicell upset events were observed,and an uppermost number of nine upset cells were discovered in the 90 MeV proton irradiation test.The results indicate that the SEE sensitivities of the 28 nm SoC to the 90 MeV and 70 MeV protons were similar.Cosmic Ray Effects on Micro-Electronics Monte Carlo simulations were analyzed,and it demonstrates that protons can induce effects in a 28 nm SoC if their energies are greater than 1.4 MeV and that the lowest corresponding linear energy transfer was 0.142 MeV cm^2 mg^-1.The similarities and discrepancies of the SEEs induced by the 90 MeV and 70 MeV protons were analyzed.
文摘Approximately 25%of patients diagnosed with pancreatic cancer present with non-metastatic resectable or borderline resectable disease.Unfortunately,the cure rate for these“curable”patients is only in the range of 20%.Local-regional failure rates may exceed 50%after margin-negative,node-negative pancreatectomy,but up to 80%of resections are associated with regional lymph node or margin positivity.While systemic drug therapy and chemotherapy may prevent or delay the appearance of distant metastases,it is unlikely to have a significant impact on local-regional disease control.Preoperative radiotherapy would represent a rational intervention to improve local-regional control.The barrier to preoperative radiotherapy is the concern that it could potentially complicate what is already a long and complicated operation.When the radiotherapy is delivered with X-rays(photons),the entire cylinder of the abdomen is irradiated;therefore,an operating surgeon may be reluctant to accept the associated risk of increased toxicity.When preoperative radiotherapy is delivered with protons,however,significant bowel and gastric tissue-sparing is achieved and clinical outcomes indicate that proton therapy does not increase the risk of operative complications nor extend the length of the procedure.
基金supported by National Natural Science Foundation of China(Nos.11822401,41674177 and 41874208).
文摘Most protons in the solar wind belong to one of two different populations,the less dense beam protons and the denser core protons.The beam protons,with a velocity of(1-2)V_(A)(V_(A)is the local Alfvén speed),always drift relative to the core protons;this kind of distribution is unstable and stimulates several kinds of wave mode.In this study,using a 2 D hybrid simulation model,we find that the original right-handed elliptically polarized Alfvén waves become linearly polarized,and eventually become right-handed and circularly polarized.Given that linearly polarized waves are a superposition of left-handed and right-handed waves,cyclotron resonance in the right-handed/left-handed component heats beam/core protons perpendicularly.The resonance between beam protons and right-handed polarized waves is stronger when the beam relative density is lower,resulting in more dramatic perpendicular heating of beam protons,whereas the situation is reversed when the beam relative density is larger.
文摘It was investigated how react molecular clusters in water, starch, bio-matrices, polymers and in quartz on gravitation radiation from planets. Gravitation radiation (GR) was found to influence the proton jumping in hydrogen bonds that stabilize the cluster structure. There was given a method calculating parameters of GR as well as a mechanism of its resonance interaction with weak GR from molecular matter (WGR). WGR has been defined as the result of proton dissolving in vacuum connected with its simultaneous condensation in the nearest free space. Both dissolving and condensation proceed with super light velocity. The gravitation wave length has been determined experimentally and it depends on the planet masses (between Earth and Sun λ ≥ 62 km, between Earth and Milky Way center λ ≥ 330 km). GR has been characterized with super light velocity. After analyzing the Sun influence on water two forms of protons were found: in a condensed and dissolved state. A new model for the atomic nucleus has been suggested according to which the protons in the nucleus oscillate between condensed and dissolved state, where in the case of isotopes this state is partially destroyed. The models for H2 and Be shall be given. Electron orbitals in atoms and molecules were found to be caused by a stationary front of shock waves from condensing protons.
基金This work is financially supported by Key Program of National Natural Science Foundation of China(No 50431020)
文摘Ground simulation tests of proton irradiation for Kapton films were conducted using the space synthesis irradiating facility,in which the energy of protons was chosen as 90 keV,and the flux was 5.0×1011 cm-2·s-1.After proton irradiation some bulges like fingers appears on the surface of Kapton and the surface roughness increases apparently.UV/Vis analysis demonstrates that the irradiation leads to the red shifting in the edge of optical absorption and a strong increase in absorbance in the visible region.X-ray photoelectron spectroscopy(XPS) analysis indicates that the enrichment of carbon atom due to the bond breaking and reconstruction during the irradiation results in the degradation of the optical properties.
基金partially supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Nos.XDB16 and XDPB09)the National Natural Science Foundation of China(Nos.11890714 and 11421505)the Key Research Program of Frontier Sciences of the CAS(No.QYZDJ-SSW-SLH002)
文摘The neutron yield in the12C(d,n)13N reaction and the proton yield in the12C(d,p)13C reaction have been measured using deuteron beams of energies 0.6-3 MeV.The deuteron beam is delivered from a 4-MeV electrostatic accelerator and bombarded on a thick carbon target.The neutrons are detected at 0°,24°,and 48°and the protons at135°in the laboratory frame.Further,the ratio of the neutron yield to the proton yield was calculated.This can be used to effectively recognize the resonances.The resonances are found at 1.4 MeV,1.7 MeV,and 2.5 MeV in the12C(d,p)13C reaction,and at 1.6 MeV and 2.7 MeV in the12C(d,n)13N reaction.The proposed method provides a way to reduce systematic uncertainty and helps confirm more resonances in compound nuclei.
基金supported by the National Natural Science Foundation of China(Grant Nos.11905206 and 11975217).
文摘Zirconium tritiated(ZrTx)is an alternative target material for deuteron-triton(D-T)reaction neutron generator.The isotopic replacement and microstructure evolution induced by hydrogen isotope implantation could significantly affect the performance of the target film.In this work,the zirconium deuteride film deposited on Mo/Si substrate was implanted by 150 keV protons with fluence from 1×10^(16 ) to 1×10^(18 )protons/cm^(2).After implantation,the depth profiles of retained hydrogen(H)and deuterium(D)in these target films were analyzed by elastic recoil detection analysis(ERDA),and time of flight-secondary ion mass spectrometry(ToF-SIMS).Additionally,the microstructure evolution was also observed by x-ray diffraction(XRD)and scanning electron microscope(SEM).The D concentration in the ZrDx film decreased versus the proton implantation fluence.An analytical model was proposed to describe the hydrogen isotopic trapping and exchange as functions of incident protons fluence.Additionally,the XRD analysis revealed that no new phase was formed after proton implantation.Furthermore,circular flakings were observed on the ZrDx surface from SEM images at fluence up to 1×10^(18) protons/cm^(2),and this surface morphology was considered to associate with the hydrogen atoms congregation in Mo/Si boundary.
文摘Analysis of solar-cell array panel (SAP) data from the Arase satellite orbiting in the inner magnetosphere showed a clear degradation of solar cells that could be attributed to trapped protons with energies greater than 6 MeV. Proton fluence was determined based on variations in the open-circuit voltage (Voc) of the solar cells, which we compared with that expected based on various distribution models (AP8MAX, AP9 mean and CRRESPRO quiet) of trapped protons. We found a general agreement, confirming the major contribution of trapped protons to the degradation, as well as a slight difference in the fluence expected based on the model calculations. To minimize this difference, we slightly modified the models, and found that concentrating the energetic protons on the magnetic equator provided a better agreement. Our results indicate that >6 MeV protons also has the equatorial concentration as reported for >18 MeV protons from the Van Allen Probes observation, and are interpreted as two components of the trapped protons, i.e., those of solar energetic particle (SEP) origin have an anisotropic pitch-angle distribution and are confined near the magnetic equator.
基金Supported by the National Natural Science Foundation of China(12065014,12047501)the Natural Science Foundation of Gansu province,China(22JR5RA266)the West Light Foundation of the Chinese Academy of Sciences(21JR7RA201)
文摘Inspired by the recent near-threshold J/ψphotoproduction measurements,we discuss gluon gravitational form factors(GFFs)and internal properties of the proton.This work presents a complete analysis of the proton gluon GFFs connecting the gluon part of the energy-momentum tensor and the heavy quarkonium photoproduction.In particular,a global fitting of the J/ψdifferential and total cross section experimental data is used to determine the gluon GFFs as functions of the squared momentum transfer t.Combined with the quark contributions to the D-term form factor extracted from the deeply virtual Compton scattering experiment,the total D-term is obtained to investigate their applications in describing the proton mechanical properties.These studies provide a unique perspective on investigating the proton gluon GFFs and important information for enhancing QCD constraints on the gluon GFFs.
基金National Natural Science Foundation of China(Grant No.12075227)the National Natural Science Foundation of China-NSAF(Grant No.U2130121)+1 种基金the National Key Research and Development Program of China(Grant No.2016YFA0401102)the Science Challenge Project(Grant No.TZ2018005).
文摘The target backsheath field acceleration mechanism is one of the main mechanisms of laser-driven proton acceleration(LDPA)and strongly depends on the comprehensive performance of the ultrashort ultra-intense lasers used as the driving sources.The successful use of the SG-II Peta-watt(SG-II PW)laser facility for LDPA and its applications in radiographic diagnoses have been manifested by the good performance of the SG-II PW facility.Recently,the SG-II PW laser facility has undergone extensive maintenance and a comprehensive technical upgrade in terms of the seed source,laser contrast and terminal focus.LDPA experiments were performed using the maintained SG-II PW laser beam,and the highest cutoff energy of the proton beam was obviously increased.Accordingly,a double-film target structure was used,and the maximum cutoff energy of the proton beam was up to 70 MeV.These results demonstrate that the comprehensive performance of the SG-II PW laser facility was improved significantly.
基金supported by the National Research Foundation (NRF) grant funded by the Korea government (NRF2022R1C1C1007619, NRF-2021M3H4A1A01002921, NRF2021M3I3A1084292)supported by the KIST Institutional Program (Project No. 2E32592-23-069)。
文摘PrBa_(0.5)Sr_(0.5)Co_(1.5)Fe_(0.5)O_(5+δ)(PrBSCF) has attracted much research interest as a potential triple ionic and electronic conductor(TIEC) electrode for protonic ceramic fuel cells(PCFCs). The chemical formula for Pr BSCF is AA'B_(2)O_(5+δ), with Pr(A-site) and Ba/Sr(A'-site) alternately stacked along the c-axis. Due to these structural features, the bulk oxygen ion diffusivity is significantly enhanced through the disorder-free channels in the PrO layer;thus, the A site cations(lanthanide ions) play a pivotal role in determining the overall electrochemical properties of layered perovskites. Consequently, previous research has predominantly focused on the electrical properties and oxygen bulk/surface kinetics of Ln cation effects,whereas the hydration properties for PCFC systems remain unidentified. Here, we thoroughly examined the proton uptake behavior and thermodynamic parameters for the hydration reaction to conclusively determine the changes in the electrochemical performances depending on LnBa_(0.5)Sr_(0.5)Co_(1.5)Fe_(0.5)O_(5+δ)(LnBSCF,Ln=Pr, Nd, and Gd) cathodes. At 500 ℃, the quantitative proton concentration of PrBSCF was 2.04 mol% and progressively decreased as the Ln cation size decreased. Similarly, the Gibbs free energy indicated that less energy was required for the formation of protonic defects in the order of Pr BSCF < Nd BSCF < Gd BSCF. To elucidate the close relationship between hydration properties and electrochemical performances in LnBSCF cathodes, PCFC single cell measurements and analysis of the distribution of relaxation time were further investigated.
基金This work was supported by National Natural Science Foundation of China(No.12222513).
文摘Radio frequency quadrupoles(RFQs),which are crucial components of proton injectors,significantly affect the performance of proton accelerator facilities.An RFQ with a high frequency of 714 MHz dedicated to compact proton injectors for medi-cal applications is designed in this study.The RFQ is designed to accelerate proton beams from 50 keV to 4 MeV within a short length of 2 m and can be matched closely with the downstream drift tube linac to capture more particles through a preliminary optimization.To develop an advanced RFQ,challenging techniques,including fabrication and tuning method,must be evaluated and verified using a prototype.An aluminium prototype is derived from the conceptual design of the RFQ and then redesigned to confirm the radio frequency performance,fabrication procedure,and feasibility of the tuning algorithm.Eventually,a new tuning algorithm based on the response matrix and least-squares method is developed,which yields favorable results based on the prototype,i.e.,the errors of the dipole and quadrupole components reduced to a low level after several tuning iterations.Benefiting from the conceptual design and techniques obtained from the prototype,the formal mechanical design of the 2-m RFQ is ready for the next manufacturing step.
