Machine learning methods have proven to be powerful in various research fields.In this paper,we show that research on radiation effects could benefit from such methods and present a machine learning-based scientific d...Machine learning methods have proven to be powerful in various research fields.In this paper,we show that research on radiation effects could benefit from such methods and present a machine learning-based scientific discovery approach.The total ionizing dose(TID)effects usually cause gain degradation of bipolar junction transistors(BJTs),leading to functional failures of bipolar integrated circuits.Currently,many experiments of TID effects on BJTs have been conducted at different laboratories worldwide,producing a large amount of experimental data which provides a wealth of information.However,it is difficult to utilize these data effectively.In this study,we proposed a new artificial neural network(ANN)approach to analyze the experimental data of TID effects on BJTs An ANN model was built and trained using data collected from different experiments.The results indicate that the proposed ANN model has advantages in capturing nonlinear correlations and predicting the data.The trained ANN model suggests that the TID hardness of a BJT tends to increase with base current I.A possible cause for this finding was analyzed and confirmed through irradiation experiments.展开更多
To explore the survival and dose response of organism for different radiation sources is of great importance in the research of radiobiology. In this study, the survival-dose response of Deinococcus radiodurans (E.col...To explore the survival and dose response of organism for different radiation sources is of great importance in the research of radiobiology. In this study, the survival-dose response of Deinococcus radiodurans (E.coli, as the control) for ultra-violet (UV), γ-rays radiation and ion beam exposure was investigated. The shoulder type of survival curves were found for both UV and γ-ray ionizing radiation, but the saddle type of survival curves were shown for H+、 N+( 20keV and 30keV) and Ar+ beam exposure. This dose effect of the survival initially decreased with the increase in dose and then increased in the high dose range and finally decreased again in the higher dose range. Our experimental results suggest that D. radiodurans, which is considerably radio-resistant to UV and x-ray and γ-ray ionizing radiation, do not resist ion beam exposure.展开更多
Because of the discrete charge storage mechanism, charge trapping memory（CTM） technique is a good candidate for aerospace and military missions. The total ionization dose（TID） effects on CTM cells with Al2O3/HfO2/...Because of the discrete charge storage mechanism, charge trapping memory（CTM） technique is a good candidate for aerospace and military missions. The total ionization dose（TID） effects on CTM cells with Al2O3/HfO2/Al2O3（AHA） high-k gate stack structure under in-situ 10 keV x-rays are studied. The C-V characteristics at different radiation doses demonstrate that charge stored in the device continues to be leaked away during the irradiation,thereby inducing the shift of flat band voltage（V（fb））. The dc memory window shows insignificant changes, suggesting the existence of good P/E ability. Furthermore, the physical mechanisms of TID induced radiation damages in AHA-based CTM are analyzed.展开更多
Total dose effects and annealing behavior of domestic n-channel VDMOS devices under different bias conditions were investigated. The dependences of typical electrical parameters such as threshold voltage, breakdown vo...Total dose effects and annealing behavior of domestic n-channel VDMOS devices under different bias conditions were investigated. The dependences of typical electrical parameters such as threshold voltage, breakdown voltage, leakage current, and on-state resistance upon total dose were discussed. We also observed the relationships between these parameters and annealing time. The experiment results show that： the threshold voltage negatively shifts with the increasing of total dose and continues to decrease at the beginning of 100 ℃ annealing; the breakdown voltage under the drain bias voltage has passed through the pre-irradiation threshold voltage during annealing behaving with a ＂rebound＂ effect; there is a latent interface-trap buildup （LITB） phenomenon in the VDMOS devices; the leakage current is suppressed; and on-state resistance is almost kept constant during irradiation and annealing. Our experiment results are meaningful and important for further improvements in the design and processing.展开更多
This paper investigates the total ionizing dose response of different non-planar triple-gate transistor structures with different fin widths. By exposing the pseudo-MOS transistor to different amounts of radiation, di...This paper investigates the total ionizing dose response of different non-planar triple-gate transistor structures with different fin widths. By exposing the pseudo-MOS transistor to different amounts of radiation, different interface trap densities and trapped-oxide charges can be obtained. Using these parameters together with Altal 3D simulation software, the total dose radiation response of various non-planar triple-gate devices can be simulated. The behaviors of three kinds of non-planar devices are compared.展开更多
The effects of 1 Me V electron irradiation in air at a fixed accumulated dose and dose rates of 393.8,196.9,78.8,and 39.4 Gy s^(-1)on a shape memory epoxy(SMEP)resin were studied.Under low-dose-rate irradiation,accele...The effects of 1 Me V electron irradiation in air at a fixed accumulated dose and dose rates of 393.8,196.9,78.8,and 39.4 Gy s^(-1)on a shape memory epoxy(SMEP)resin were studied.Under low-dose-rate irradiation,accelerated degradation of the shape memory performance was observed;specifically,the shape recovery ratio decreased exponentially with increasing irradiation time(that is,with decreasing dose rate).In addition,the glass transition temperature of the SMEP,as measured by dynamic mechanical analysis,decreased overall with decreasing dose rate.The dose rate effects of 1 Me V electron irradiation on the SMEP were confirmed by structural analysis using electron paramagnetic resonance(EPR)spectroscopy and Fourier transform infrared(FTIR)spectroscopy.The EPR spectra showed that the concentration of free radicals increased exponentially with increasing irradiation time.Moreover,the FTIR spectra showed higher intensities of the peaks at 1660 and 1720 cm^(-1),which are attributed to stretching vibrations of amide C=O and ketone/acid C=O,at lower dose rates.The intensities of the IR peaks at 1660 and 1720 cm^(-1) increased exponentially with increasing irradiation time,and the relative intensity of the IR peak at 2926 cm^(-1)decreased exponentially with increasing irradiation time.The solid-state13 C nuclear magnetic resonance(NMR)spectra of the SMEP before and after 1 Me V electron irradiation at a dose of 1970 k Gy and a dose rate of 78.8 Gy s^(-1) indicated damage to the CH_(2)–N groups and aliphatic isopropanol segment.This result is consistent with the detection of nitrogenous free radicals,a phenoxy-type free radical,and several types of pyrolytic carbon radicals by EPR.During the subsequent propagation process,the free radicals produced at lower dose rates were more likely to react with oxygen,which was present at higher concentrations,and form the more destructive peroxy free radicals and oxidation products such as acids,amides,and ketones.The increase in peroxy free radicals at lower dose rates was thought to accelerate the degradation of the macroscopic performance of the SMEP.展开更多
The influence of total dose irradiation on hot-carrier reliability of 65 nm n-type metal-oxide-semiconductor field- effect transistors （nMOSFETs） is investigated. Experimental results show that hot-carrier degradati...The influence of total dose irradiation on hot-carrier reliability of 65 nm n-type metal-oxide-semiconductor field- effect transistors （nMOSFETs） is investigated. Experimental results show that hot-carrier degradations on ir- radiated narrow channel nMOSFETs are greater than those without irradiation. The reason is attributed to radiation-induced charge trapping in shallow trench isolation （STI）. The electric field in the pinch-off region of the nMOSFET is enhanced by radiation-induced charge trapping in STI, resulting in a more severe hot-carrier effect.展开更多
A digital-to-analog converter （DAC） in CBCMOS technology was irradiated by 60Co F-rays at various dose rates and biases for investigating the ionizing radiation response of the DAC. The radiation responses show that...A digital-to-analog converter （DAC） in CBCMOS technology was irradiated by 60Co F-rays at various dose rates and biases for investigating the ionizing radiation response of the DAC. The radiation responses show that the function curve and the key electrical parameters of the DAC in CBCMOS technology are sensitive to total dose and dose rates. Under different bias conditions, the radiation failure levels were different, and the radiation damage under operation bias conditions was more severe. Finally, test results were preliminarily analyzed by relating the failure mode to DAC architecture and process technology.展开更多
Laser-assisted simulation technique has played a crucial role in the investigation of dose rate effects of silicon-based devices and integrated circuits,due to its exceptional advantages in terms of flexibility,safety...Laser-assisted simulation technique has played a crucial role in the investigation of dose rate effects of silicon-based devices and integrated circuits,due to its exceptional advantages in terms of flexibility,safety,convenience,and precision.In recent years,wide band gap materials,known for their strong bonding and high ionization energy,have gained increasing attention from researchers and hold significant promise for extensive applications in specialized environments.Consequently,there is a growing need for comprehensive research on the dose rate effects of wide band gap materials.In response to this need,the use of laser-assisted simulation technology has emerged as a promising approach,offering an effective means to assess the efficacy of investigating these materials and devices.This paper focused on investigating the feasibility of laser-assisted simulation to study the dose rate effects of wide band gap semiconductor devices.Theoretical conversion factors for laser-assisted simulation of dose rate effects of GaN-based and SiC-based devices were been provided.Moreover,to validate the accuracy of the conversion factors,pulsed laser and dose rate experiments were conducted on GaN-based and SiC-based PIN diodes.The results demonstrate that pulsed laser radiation andγ-ray radiation can produce highly similar photocurrent responses in GaN-based and SiC-based PIN diodes,with correlation coefficients of 0.98 and 0.974,respectively.This finding reaffirms the effectiveness of laser-assisted simulation technology,making it a valuable complement in studying the dose rate effects of wide band gap semiconductor devices.展开更多
The total ionizing dose radiation effects in the polycrystalline silicon thin film transistors are studied. Transfer characteristics, high-frequency capacitance-voltage curves and low-frequency noises (LFN) are measur...The total ionizing dose radiation effects in the polycrystalline silicon thin film transistors are studied. Transfer characteristics, high-frequency capacitance-voltage curves and low-frequency noises (LFN) are measured before and after radiation. The experimental results show that threshold voltage and hole-field-effect mobility decrease, while sub-threshold swing and low-frequency noise increase with the increase of the total dose. The contributions of radiation induced interface states and oxide trapped charges to the shift of threshold voltage are also estimated. Furthermore, spatial distributions of oxide trapped charges before and after radiation are extracted based on the LFN measurements.展开更多
A survey involving 6103 participants from five Chinese provinces was conducted to evaluate the threshold value of urinary cadmium （UCd） for renal dysfunction as benchmark dose low （BMDL）. The urinary N-acetyl-13-D...A survey involving 6103 participants from five Chinese provinces was conducted to evaluate the threshold value of urinary cadmium （UCd） for renal dysfunction as benchmark dose low （BMDL）. The urinary N-acetyl-13-D-glucosaminidase （UNAG） was chosen as an effect biomarker. The UCd BMDLs for UNAG ranged from 2.18μg/g creatinine （cr） to 4.26μg/g cr in the populations of different provinces. The selection of the sample population and area affect the evaluation of the BMDL. The reference level of UCd for renal effects was further evaluated based on the data of all 6103 subjects. With benchmark responses （BMR） of 10%/5%, the overall UCd BMDLs for males in the total population were 3.73/2.08 μg/g cr. The BMD was slightly lower in females, thereby indicating that females may be relatively more sensitive to Cd exposure than are males.展开更多
Objective To investigate the effects of Glibenclamide on reduction of secondary damage after acute spinal cord injury in rats.Methods Ninety rats were randomly divided into control group(laminectomy alone),spinal cord...Objective To investigate the effects of Glibenclamide on reduction of secondary damage after acute spinal cord injury in rats.Methods Ninety rats were randomly divided into control group(laminectomy alone),spinal cord injury group(injury group),and treatment group(treated展开更多
Total dose effects and single event effects on radiation-hardened power vertical double-diffusion metal oxide semiconductor（VDMOS） devices with composite SiO2-Si3N4 film gates are investigated.The relationships amon...Total dose effects and single event effects on radiation-hardened power vertical double-diffusion metal oxide semiconductor（VDMOS） devices with composite SiO2-Si3N4 film gates are investigated.The relationships among the important electrical parameters of the samples with different thickness SiO2-Si3N4 films,such as threshold voltage,breakdown voltage,and on-state resistance in accumulated dose,are discussed.The total dose experiment results show that the breakdown voltage and the on-state resistance barely change with the accumulated dose.However,the relationships between the threshold voltages of the samples and the accumulated dose are more complex,and not only positively drift,but also negatively drift.At the end of the total dose experiment,we select the group of samples which have the smaller threshold voltage shift to carry out the single event effect studies.We find that the samples with appropriate thickness ratio SiO2-Si3N4 films have a good radiation-hardening ability.This method may be useful in solving both the SEGR and the total dose problems with the composite SiO2-Si3N4 films.展开更多
This paper investigates the effects of gamma-ray irradiation on the Shallow-Trench Isolation （STI） leakage currents in 180-nm complementary metal oxide semiconductor technology. No hump effect in the subthreshold re...This paper investigates the effects of gamma-ray irradiation on the Shallow-Trench Isolation （STI） leakage currents in 180-nm complementary metal oxide semiconductor technology. No hump effect in the subthreshold region is observed after irradiation, which is considered to be due to the thin STI corner oxide thickness. A negative substrate bias could effectively suppress the STI leakage, but it also impairs the device characteristics. The three-dimensional simulation is introduced to understand the impact of substrate bias, Moreover, we propose a simple method for extracting the best substrate bias value, which not only eliminates the STI leakage but also has the least impact on the device characteristics.展开更多
Human umbilical cord mesenchymal stem cells(hUC-MSCs)are a promising candidate for spinal cord injury(SCI)repair owing to their advantages of low immunogenicity and easy accessibility over other MSC sources.However,mo...Human umbilical cord mesenchymal stem cells(hUC-MSCs)are a promising candidate for spinal cord injury(SCI)repair owing to their advantages of low immunogenicity and easy accessibility over other MSC sources.However,modest clinical efficacy hampered the progression of these cells to clinical translation.This discrepancy may be due to many variables,such as cell source,timing of implantation,route of administration,and relevant efficacious cell dose,which are critical factors that affect the efficacy of treatment of patients with SCI.Previously,we have evaluated the safety and efficacy of 4×10^(6) hUC-MSCs/kg in the treatment of subacute SCI by intrathecal implantation in rat models.To search for a more accurate dose range for clinical translation,we compared the effects of three different doses of hUC-MSCs-low(0.25×10^(6) cells/kg),medium(1×10^(6) cells/kg)and high(4×10^(6) cells/kg)-on subacute SCI repair through an elaborate combination of behavioral analyses,anatomical analyses,magnetic resonance imaging-diffusion tensor imaging(MRI-DTI),biotinylated dextran amine(BDA)tracing,electrophysiology,and quantification of mRNA levels of ion channels and neurotransmitter receptors.Our study demonstrated that the medium dose,but not the low dose,is as efficient as the high dose in producing the desired therapeutic outcomes.Furthermore,partial restoration of theγ-aminobutyric acid type A(GABAA)receptor expression by the effective doses indicates that GABAA receptors are possible candidates for therapeutic targeting of dormant relay pathways in injured spinal cord.Overall,this study revealed that intrathecal implantation of 1×10^(6) hUC-MSCs/kg is an alternative approach for treating subacute SCI.展开更多
Annular gate nMOSFETs are frequently used in spaceborne integrated circuits due to their intrinsic good capability of resisting total ionizing dose （TID） effect. However, their capability of resisting the hot carrie...Annular gate nMOSFETs are frequently used in spaceborne integrated circuits due to their intrinsic good capability of resisting total ionizing dose （TID） effect. However, their capability of resisting the hot carrier effect （HCE） has also been proven to be very weak. In this paper, the reason why the annular gate nMOSFETs have good TID but bad HCE resistance is discussed in detail, and an improved design to locate the source contacts only along one side of the annular gate is used to weaken the HCE degradation. The good TID and HCE hardened capability of the design are verified by the experiments for I/O and core nMOSFETs in a 0.18 μm bulk CMOS technology. In addition, the shortcoming of this design is also discussed and the TID and the HCE characteristics of the replacers （the annular source nMOSFETs） are also studied to provide a possible alternative for the designers.展开更多
Acupuncture therapy is widely used in the clinic,and its therapeutic effects have been proven by numerous studies.The dose–effect relationship of acupuncture is a fundamental aspect of the acupuncture research system...Acupuncture therapy is widely used in the clinic,and its therapeutic effects have been proven by numerous studies.The dose–effect relationship of acupuncture is a fundamental aspect of the acupuncture research system.Recent studies found that different acupuncture dosages altered study results directly,indicating the importance of screening the optimal stimulation dosage.However,the system for studying the acupuncture dose–effect relationship is still in its infancy,and the methodology of the system needs to be improved.This review aimed to define the factors impacting acupuncture“dosage”and“effect,”and to improve the methodological system for research on the dose–effect relationship of acupuncture.By summarizing the current findings of acupuncture dose–effect studies,we discussed the vital acupuncture parameters and methodological problems that influence the relationship between acupuncture dosage and its effects.These factors consist of specific influencing factors(acupoint selection,acupuncture manipulation parameters,de qi response)and nonspecific influencing factors(comparison selection,blinding procedure,patient expectancy).Our perspectives offer suggestions for the design of acupuncture dosage–effect trials.Further studies need to be conducted to establish the methodological system and provide systematic evidence of the acupuncture dose–effect relationship.展开更多
It is first reported in the present paper that whole-body irradiation (WBI) with low dose X-rays could increase intracellular calcium ions ([Ca2+]i) and stimulate protein kinase C (PKC) activity of mouse lymphocytes. ...It is first reported in the present paper that whole-body irradiation (WBI) with low dose X-rays could increase intracellular calcium ions ([Ca2+]i) and stimulate protein kinase C (PKC) activity of mouse lymphocytes. Following WBI of male Kunming micc With 75 mGy X-rays at a dose rate of 12.5 mGy/min the mobilization of [Ca2+]i with Con A in CD4+ and CD8+ Cells in the thymus and spleen was potentiated and the amplitude of [Ca2+], mobilization in thymocytes in response to anti-CD3 monoclonal antibody increased with time from 4 to 24 h following low dose radiation. The PKC activity in the homogenate of spleen was markedly stimulated 12 h after WBl with 75 mGy, reaching its peak value at 24-48 h and coming down to lower than normal on day 7. However, the PKC activity in the separated T lymphocytes reached its peak value at 12 h and that in the B lymphocytes reached its peak value on day 4, both coming down to below control on day 7. The implications of this facilitation of signal transduction in T lymphocytes in the mechanism of immunoenhancement after low dose radiation were discussed展开更多
Radiation effects of the floating gate read-only-memory （FG ROM） and the static random access memory （SRAM） have been evaluated using the 14 MeV neutron and 31.9MeV proton beams and Co-60 γ-rays. The neutron flue...Radiation effects of the floating gate read-only-memory （FG ROM） and the static random access memory （SRAM） have been evaluated using the 14 MeV neutron and 31.9MeV proton beams and Co-60 γ-rays. The neutron fluence, when the first error occurs in the FG ROMs, is at least 5 orders of magnitude higher than that in the SRAMs, and the proton fluence, 4 orders of magnitude higher. The total dose threshold for Co-60 γ-ray irradiation is about 104 rad （Si） for both memories. The difference and similarity are attributed to the structure of the memory cells and the mechanism of radiation effects. It is concluded that the FG ROMs are more reliable as semiconductor memories for storing data than the SRAMs, when they are used in the satellites or space crafts exposed to high energy particle radiation.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 11690040 and 11690043)。
文摘Machine learning methods have proven to be powerful in various research fields.In this paper,we show that research on radiation effects could benefit from such methods and present a machine learning-based scientific discovery approach.The total ionizing dose(TID)effects usually cause gain degradation of bipolar junction transistors(BJTs),leading to functional failures of bipolar integrated circuits.Currently,many experiments of TID effects on BJTs have been conducted at different laboratories worldwide,producing a large amount of experimental data which provides a wealth of information.However,it is difficult to utilize these data effectively.In this study,we proposed a new artificial neural network(ANN)approach to analyze the experimental data of TID effects on BJTs An ANN model was built and trained using data collected from different experiments.The results indicate that the proposed ANN model has advantages in capturing nonlinear correlations and predicting the data.The trained ANN model suggests that the TID hardness of a BJT tends to increase with base current I.A possible cause for this finding was analyzed and confirmed through irradiation experiments.
基金the National Natural Science Foundation of China! No.196O5005)
文摘To explore the survival and dose response of organism for different radiation sources is of great importance in the research of radiobiology. In this study, the survival-dose response of Deinococcus radiodurans (E.coli, as the control) for ultra-violet (UV), γ-rays radiation and ion beam exposure was investigated. The shoulder type of survival curves were found for both UV and γ-ray ionizing radiation, but the saddle type of survival curves were shown for H+、 N+( 20keV and 30keV) and Ar+ beam exposure. This dose effect of the survival initially decreased with the increase in dose and then increased in the high dose range and finally decreased again in the higher dose range. Our experimental results suggest that D. radiodurans, which is considerably radio-resistant to UV and x-ray and γ-ray ionizing radiation, do not resist ion beam exposure.
基金Supported by the National Natural Science Foundation of China under Grant No 616340084the Youth Innovation Promotion Association of Chinese Academy of Sciences under Grant No 2014101+1 种基金the International Cooperation Project of Chinese Academy of Sciencesthe Austrian-Chinese Cooperative R&D Projects under Grant No 172511KYSB20150006
文摘Because of the discrete charge storage mechanism, charge trapping memory（CTM） technique is a good candidate for aerospace and military missions. The total ionization dose（TID） effects on CTM cells with Al2O3/HfO2/Al2O3（AHA） high-k gate stack structure under in-situ 10 keV x-rays are studied. The C-V characteristics at different radiation doses demonstrate that charge stored in the device continues to be leaked away during the irradiation,thereby inducing the shift of flat band voltage（V（fb））. The dc memory window shows insignificant changes, suggesting the existence of good P/E ability. Furthermore, the physical mechanisms of TID induced radiation damages in AHA-based CTM are analyzed.
文摘Total dose effects and annealing behavior of domestic n-channel VDMOS devices under different bias conditions were investigated. The dependences of typical electrical parameters such as threshold voltage, breakdown voltage, leakage current, and on-state resistance upon total dose were discussed. We also observed the relationships between these parameters and annealing time. The experiment results show that： the threshold voltage negatively shifts with the increasing of total dose and continues to decrease at the beginning of 100 ℃ annealing; the breakdown voltage under the drain bias voltage has passed through the pre-irradiation threshold voltage during annealing behaving with a ＂rebound＂ effect; there is a latent interface-trap buildup （LITB） phenomenon in the VDMOS devices; the leakage current is suppressed; and on-state resistance is almost kept constant during irradiation and annealing. Our experiment results are meaningful and important for further improvements in the design and processing.
基金supported by the National Science Foundation for Young Scholars of China(No.11105092)the Shenzhen Science and Technology Development Funds(Nos.JC201005280565A,JC201005280558A,GJHS20120621142118853)
文摘This paper investigates the total ionizing dose response of different non-planar triple-gate transistor structures with different fin widths. By exposing the pseudo-MOS transistor to different amounts of radiation, different interface trap densities and trapped-oxide charges can be obtained. Using these parameters together with Altal 3D simulation software, the total dose radiation response of various non-planar triple-gate devices can be simulated. The behaviors of three kinds of non-planar devices are compared.
基金support of the 111 Project(No.B18017)the National Equipment Pre-Research Project of the 13th Five-Year Plan(No.30508040601)。
文摘The effects of 1 Me V electron irradiation in air at a fixed accumulated dose and dose rates of 393.8,196.9,78.8,and 39.4 Gy s^(-1)on a shape memory epoxy(SMEP)resin were studied.Under low-dose-rate irradiation,accelerated degradation of the shape memory performance was observed;specifically,the shape recovery ratio decreased exponentially with increasing irradiation time(that is,with decreasing dose rate).In addition,the glass transition temperature of the SMEP,as measured by dynamic mechanical analysis,decreased overall with decreasing dose rate.The dose rate effects of 1 Me V electron irradiation on the SMEP were confirmed by structural analysis using electron paramagnetic resonance(EPR)spectroscopy and Fourier transform infrared(FTIR)spectroscopy.The EPR spectra showed that the concentration of free radicals increased exponentially with increasing irradiation time.Moreover,the FTIR spectra showed higher intensities of the peaks at 1660 and 1720 cm^(-1),which are attributed to stretching vibrations of amide C=O and ketone/acid C=O,at lower dose rates.The intensities of the IR peaks at 1660 and 1720 cm^(-1) increased exponentially with increasing irradiation time,and the relative intensity of the IR peak at 2926 cm^(-1)decreased exponentially with increasing irradiation time.The solid-state13 C nuclear magnetic resonance(NMR)spectra of the SMEP before and after 1 Me V electron irradiation at a dose of 1970 k Gy and a dose rate of 78.8 Gy s^(-1) indicated damage to the CH_(2)–N groups and aliphatic isopropanol segment.This result is consistent with the detection of nitrogenous free radicals,a phenoxy-type free radical,and several types of pyrolytic carbon radicals by EPR.During the subsequent propagation process,the free radicals produced at lower dose rates were more likely to react with oxygen,which was present at higher concentrations,and form the more destructive peroxy free radicals and oxidation products such as acids,amides,and ketones.The increase in peroxy free radicals at lower dose rates was thought to accelerate the degradation of the macroscopic performance of the SMEP.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11475255,U1532261 and 11505282
文摘The influence of total dose irradiation on hot-carrier reliability of 65 nm n-type metal-oxide-semiconductor field- effect transistors （nMOSFETs） is investigated. Experimental results show that hot-carrier degradations on ir- radiated narrow channel nMOSFETs are greater than those without irradiation. The reason is attributed to radiation-induced charge trapping in shallow trench isolation （STI）. The electric field in the pinch-off region of the nMOSFET is enhanced by radiation-induced charge trapping in STI, resulting in a more severe hot-carrier effect.
文摘A digital-to-analog converter （DAC） in CBCMOS technology was irradiated by 60Co F-rays at various dose rates and biases for investigating the ionizing radiation response of the DAC. The radiation responses show that the function curve and the key electrical parameters of the DAC in CBCMOS technology are sensitive to total dose and dose rates. Under different bias conditions, the radiation failure levels were different, and the radiation damage under operation bias conditions was more severe. Finally, test results were preliminarily analyzed by relating the failure mode to DAC architecture and process technology.
基金National Natural Science Foundation of China(12205028)Natural Science Foundation of Sichuan Province(2022NSFSC1235)Young and Middle-aged Backbone Teacher Foundation of Chengdu University of Technology(10912-JXGG2022-08363)。
文摘Laser-assisted simulation technique has played a crucial role in the investigation of dose rate effects of silicon-based devices and integrated circuits,due to its exceptional advantages in terms of flexibility,safety,convenience,and precision.In recent years,wide band gap materials,known for their strong bonding and high ionization energy,have gained increasing attention from researchers and hold significant promise for extensive applications in specialized environments.Consequently,there is a growing need for comprehensive research on the dose rate effects of wide band gap materials.In response to this need,the use of laser-assisted simulation technology has emerged as a promising approach,offering an effective means to assess the efficacy of investigating these materials and devices.This paper focused on investigating the feasibility of laser-assisted simulation to study the dose rate effects of wide band gap semiconductor devices.Theoretical conversion factors for laser-assisted simulation of dose rate effects of GaN-based and SiC-based devices were been provided.Moreover,to validate the accuracy of the conversion factors,pulsed laser and dose rate experiments were conducted on GaN-based and SiC-based PIN diodes.The results demonstrate that pulsed laser radiation andγ-ray radiation can produce highly similar photocurrent responses in GaN-based and SiC-based PIN diodes,with correlation coefficients of 0.98 and 0.974,respectively.This finding reaffirms the effectiveness of laser-assisted simulation technology,making it a valuable complement in studying the dose rate effects of wide band gap semiconductor devices.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61574048 and 61204112the Science and Technology Research Project of Guangdong Province under Grant Nos 2015B090912002 and 2014A030313656the Pearl River S&T Nova Program of Guangzhou
文摘The total ionizing dose radiation effects in the polycrystalline silicon thin film transistors are studied. Transfer characteristics, high-frequency capacitance-voltage curves and low-frequency noises (LFN) are measured before and after radiation. The experimental results show that threshold voltage and hole-field-effect mobility decrease, while sub-threshold swing and low-frequency noise increase with the increase of the total dose. The contributions of radiation induced interface states and oxide trapped charges to the shift of threshold voltage are also estimated. Furthermore, spatial distributions of oxide trapped charges before and after radiation are extracted based on the LFN measurements.
基金financially supported by Special Funds of the State Environmental Protection Public Welfare Industry(201009049201309049)+1 种基金National Key Technology Research and Development Program of the Ministry of Science and Technology of China(2013BAI12B03)the Fundamental Research Funds for the Central Universities(2015JBM108)
文摘A survey involving 6103 participants from five Chinese provinces was conducted to evaluate the threshold value of urinary cadmium （UCd） for renal dysfunction as benchmark dose low （BMDL）. The urinary N-acetyl-13-D-glucosaminidase （UNAG） was chosen as an effect biomarker. The UCd BMDLs for UNAG ranged from 2.18μg/g creatinine （cr） to 4.26μg/g cr in the populations of different provinces. The selection of the sample population and area affect the evaluation of the BMDL. The reference level of UCd for renal effects was further evaluated based on the data of all 6103 subjects. With benchmark responses （BMR） of 10%/5%, the overall UCd BMDLs for males in the total population were 3.73/2.08 μg/g cr. The BMD was slightly lower in females, thereby indicating that females may be relatively more sensitive to Cd exposure than are males.
文摘Objective To investigate the effects of Glibenclamide on reduction of secondary damage after acute spinal cord injury in rats.Methods Ninety rats were randomly divided into control group(laminectomy alone),spinal cord injury group(injury group),and treatment group(treated
文摘Total dose effects and single event effects on radiation-hardened power vertical double-diffusion metal oxide semiconductor（VDMOS） devices with composite SiO2-Si3N4 film gates are investigated.The relationships among the important electrical parameters of the samples with different thickness SiO2-Si3N4 films,such as threshold voltage,breakdown voltage,and on-state resistance in accumulated dose,are discussed.The total dose experiment results show that the breakdown voltage and the on-state resistance barely change with the accumulated dose.However,the relationships between the threshold voltages of the samples and the accumulated dose are more complex,and not only positively drift,but also negatively drift.At the end of the total dose experiment,we select the group of samples which have the smaller threshold voltage shift to carry out the single event effect studies.We find that the samples with appropriate thickness ratio SiO2-Si3N4 films have a good radiation-hardening ability.This method may be useful in solving both the SEGR and the total dose problems with the composite SiO2-Si3N4 films.
文摘This paper investigates the effects of gamma-ray irradiation on the Shallow-Trench Isolation （STI） leakage currents in 180-nm complementary metal oxide semiconductor technology. No hump effect in the subthreshold region is observed after irradiation, which is considered to be due to the thin STI corner oxide thickness. A negative substrate bias could effectively suppress the STI leakage, but it also impairs the device characteristics. The three-dimensional simulation is introduced to understand the impact of substrate bias, Moreover, we propose a simple method for extracting the best substrate bias value, which not only eliminates the STI leakage but also has the least impact on the device characteristics.
基金supported by the National Key Research and Development Program of China,No.2017YFA0105401(to LMR)the National Natural Science Foundation of China,Nos.31671420 and 81602482(to MML)a grant from the Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diseases.
文摘Human umbilical cord mesenchymal stem cells(hUC-MSCs)are a promising candidate for spinal cord injury(SCI)repair owing to their advantages of low immunogenicity and easy accessibility over other MSC sources.However,modest clinical efficacy hampered the progression of these cells to clinical translation.This discrepancy may be due to many variables,such as cell source,timing of implantation,route of administration,and relevant efficacious cell dose,which are critical factors that affect the efficacy of treatment of patients with SCI.Previously,we have evaluated the safety and efficacy of 4×10^(6) hUC-MSCs/kg in the treatment of subacute SCI by intrathecal implantation in rat models.To search for a more accurate dose range for clinical translation,we compared the effects of three different doses of hUC-MSCs-low(0.25×10^(6) cells/kg),medium(1×10^(6) cells/kg)and high(4×10^(6) cells/kg)-on subacute SCI repair through an elaborate combination of behavioral analyses,anatomical analyses,magnetic resonance imaging-diffusion tensor imaging(MRI-DTI),biotinylated dextran amine(BDA)tracing,electrophysiology,and quantification of mRNA levels of ion channels and neurotransmitter receptors.Our study demonstrated that the medium dose,but not the low dose,is as efficient as the high dose in producing the desired therapeutic outcomes.Furthermore,partial restoration of theγ-aminobutyric acid type A(GABAA)receptor expression by the effective doses indicates that GABAA receptors are possible candidates for therapeutic targeting of dormant relay pathways in injured spinal cord.Overall,this study revealed that intrathecal implantation of 1×10^(6) hUC-MSCs/kg is an alternative approach for treating subacute SCI.
基金supported by the Key Program of the National Natural Science Foundation of China(Grant No.60836004)the National Natural Science Foundation of China(Grant Nos.61006070 and 61076025)
文摘Annular gate nMOSFETs are frequently used in spaceborne integrated circuits due to their intrinsic good capability of resisting total ionizing dose （TID） effect. However, their capability of resisting the hot carrier effect （HCE） has also been proven to be very weak. In this paper, the reason why the annular gate nMOSFETs have good TID but bad HCE resistance is discussed in detail, and an improved design to locate the source contacts only along one side of the annular gate is used to weaken the HCE degradation. The good TID and HCE hardened capability of the design are verified by the experiments for I/O and core nMOSFETs in a 0.18 μm bulk CMOS technology. In addition, the shortcoming of this design is also discussed and the TID and the HCE characteristics of the replacers （the annular source nMOSFETs） are also studied to provide a possible alternative for the designers.
基金funded by the Ministry of Science and Technology of the People’s Republic of ChinaNational Key Research and Development Program(2010CB530506,2018YFC1706001,2019YFC0840709)+2 种基金Tianjin Municipal Science and Technology BureauTianjin Science and Technology Plan Project(18PTLCSY00060)the First Teaching Hospital of Tianjin University of Traditional Chinese Medicine,Exploration and Innovation Project(YB202112)
文摘Acupuncture therapy is widely used in the clinic,and its therapeutic effects have been proven by numerous studies.The dose–effect relationship of acupuncture is a fundamental aspect of the acupuncture research system.Recent studies found that different acupuncture dosages altered study results directly,indicating the importance of screening the optimal stimulation dosage.However,the system for studying the acupuncture dose–effect relationship is still in its infancy,and the methodology of the system needs to be improved.This review aimed to define the factors impacting acupuncture“dosage”and“effect,”and to improve the methodological system for research on the dose–effect relationship of acupuncture.By summarizing the current findings of acupuncture dose–effect studies,we discussed the vital acupuncture parameters and methodological problems that influence the relationship between acupuncture dosage and its effects.These factors consist of specific influencing factors(acupoint selection,acupuncture manipulation parameters,de qi response)and nonspecific influencing factors(comparison selection,blinding procedure,patient expectancy).Our perspectives offer suggestions for the design of acupuncture dosage–effect trials.Further studies need to be conducted to establish the methodological system and provide systematic evidence of the acupuncture dose–effect relationship.
文摘It is first reported in the present paper that whole-body irradiation (WBI) with low dose X-rays could increase intracellular calcium ions ([Ca2+]i) and stimulate protein kinase C (PKC) activity of mouse lymphocytes. Following WBI of male Kunming micc With 75 mGy X-rays at a dose rate of 12.5 mGy/min the mobilization of [Ca2+]i with Con A in CD4+ and CD8+ Cells in the thymus and spleen was potentiated and the amplitude of [Ca2+], mobilization in thymocytes in response to anti-CD3 monoclonal antibody increased with time from 4 to 24 h following low dose radiation. The PKC activity in the homogenate of spleen was markedly stimulated 12 h after WBl with 75 mGy, reaching its peak value at 24-48 h and coming down to lower than normal on day 7. However, the PKC activity in the separated T lymphocytes reached its peak value at 12 h and that in the B lymphocytes reached its peak value on day 4, both coming down to below control on day 7. The implications of this facilitation of signal transduction in T lymphocytes in the mechanism of immunoenhancement after low dose radiation were discussed
文摘Radiation effects of the floating gate read-only-memory （FG ROM） and the static random access memory （SRAM） have been evaluated using the 14 MeV neutron and 31.9MeV proton beams and Co-60 γ-rays. The neutron fluence, when the first error occurs in the FG ROMs, is at least 5 orders of magnitude higher than that in the SRAMs, and the proton fluence, 4 orders of magnitude higher. The total dose threshold for Co-60 γ-ray irradiation is about 104 rad （Si） for both memories. The difference and similarity are attributed to the structure of the memory cells and the mechanism of radiation effects. It is concluded that the FG ROMs are more reliable as semiconductor memories for storing data than the SRAMs, when they are used in the satellites or space crafts exposed to high energy particle radiation.
