Machine learning-based surrogate models have significant advantages in terms of computing efficiency. In this paper, we present a pilot study on fast calibration using machine learning techniques. Technology computer-...Machine learning-based surrogate models have significant advantages in terms of computing efficiency. In this paper, we present a pilot study on fast calibration using machine learning techniques. Technology computer-aided design(TCAD) is a powerful simulation tool for electronic devices. This simulation tool has been widely used in the research of radiation effects.However, calibration of TCAD models is time-consuming. In this study, we introduce a fast calibration approach for TCAD model calibration of metal–oxide–semiconductor field-effect transistors(MOSFETs). This approach utilized a machine learning-based surrogate model that was several orders of magnitude faster than the original TCAD simulation. The desired calibration results were obtained within several seconds. In this study, a fundamental model containing 26 parameters is introduced to represent the typical structure of a MOSFET. Classifications were developed to improve the efficiency of the training sample generation. Feature selection techniques were employed to identify important parameters. A surrogate model consisting of a classifier and a regressor was built. A calibration procedure based on the surrogate model was proposed and tested with three calibration goals. Our work demonstrates the feasibility of machine learning-based fast model calibrations for MOSFET. In addition, this study shows that these machine learning techniques learn patterns and correlations from data instead of employing domain expertise. This indicates that machine learning could be an alternative research approach to complement classical physics-based research.展开更多
To obtain high-performance lithium-sulfur(Li-S)batteries,it is necessary to rationally design electrocatalytic materials that can promote efficient sulfur electrochemical reactions.Herein,the robust heterostructured m...To obtain high-performance lithium-sulfur(Li-S)batteries,it is necessary to rationally design electrocatalytic materials that can promote efficient sulfur electrochemical reactions.Herein,the robust heterostructured material of nanoscale transition metal anchored on perovskite oxide was designed for efficient catalytic kinetics of the oxidation and reduction reactions of lithium polysulphide(Li PSs),and verified by density functional theory(DFT)calculations and experimental characterizations.Due to the strong interaction of nanoscale transition metals with Li PSs through chemical coupling,heterostructured materials(STO@M)(M=Fe,Ni,Cu)exhibit excellent catalytic activity for redox reactions of Li PSs.The bifunctional heterostructure material STO@Fe exhibits good rate performance and cycling stability as the cathode host,realizing a high-performance Li-S battery that can maintain stable cycling under rapid charge-discharge cycling.This study presents a novel approach to designing electrocatalytic materials for redox reactions of Li PSs,which promotes the development of fast charge-discharge Li-S batteries.展开更多
Objective::To investigate the neuroprotective effects of simvastatin on lipopolysaccharide(LPS)-indueed rat model of Parkinson's disease(PD) and the mechanisms involved.Methods:Hemiparkinsonian rat models were ind...Objective::To investigate the neuroprotective effects of simvastatin on lipopolysaccharide(LPS)-indueed rat model of Parkinson's disease(PD) and the mechanisms involved.Methods:Hemiparkinsonian rat models were induced by stereotaxieal injection of LPS in the right substantia nigra compacts.After 2 weeks of simvastatin treatment,rotational behavior test was performed after the intraperitoneal injection of apomorphine.Expression of tyroxine hydroxylase(TH) and glial fibrillan acidic protein were analyzed through immunohistochemical staining of substantia nigra and striatum,and the level of TNF-α was evaluated using enzyme-linked immunosorbent assay.Results:Comparing with untreated group,behavioral symptoms of the rats were significantly less in the rats that received simvastatin treatment.The TH positive cell count in substantia nigra and striatum were significantly increased(P<0.05) and TNF- α expression was significantly decreased(P<0.05) in simvastatin group compared to untreated group.Conclusions:Simvastatin could effectively inhibit the activation of astrocytes,reduce TNF-α expression,and exert anti-inflammatory effects,and thus protect the dopaminergic neurons in substantia nigra and striatum of the rat model of PD.展开更多
BACKGROUND Thallium poisoning is rare and difficult to recognize.Early diagnosis and treatment of thallium-poisoned patients are essential to prevent morbidity and mortality.AIM To evaluate the efficacy of treatments ...BACKGROUND Thallium poisoning is rare and difficult to recognize.Early diagnosis and treatment of thallium-poisoned patients are essential to prevent morbidity and mortality.AIM To evaluate the efficacy of treatments and outcomes of five patients with early diagnosis of acute thallium poisoning.METHODS Five patients who consumed a thallium-contaminated meal were hospitalized in succession,and underwent clinical examinations such as blood tests and electromyography tests.Urine and blood tests confirmed the diagnosis of thallotoxicosis,revealing the occurrence of food poisoning.All patients underwent detoxification treatment,including hemoperfusion(HP)and treatment with Prussian blue(PB).A 24-mo follow-up was performed to evaluate the long-term outcomes on the patients after discharge.RESULTS Initially,the patients presented with symptoms of acute thallium poisoning including hyperalgesia of the limbs and abdominalgia,which may differ from common peripheral neuropathy.Accompanying symptoms such as hepatic damage and alopecia were observed in all the patients,which further confirmed the diagnosis of poisoning.Treatment with chelating agents was ineffective,while HP and treatment with PB drastically decreased the thallium concentration in the urine and blood.With early diagnosis and intervention,four patients had a good prognosis and no permanent sequelae.One patient developed blindness and disability during the 24-mo follow-up period.CONCLUSION Identification of incident cluster and characteristic symptoms is extremely important for early diagnosis of acute thallium poisoning.HP plus PB is essential to improve the prognosis of thallium-poisoned patients.展开更多
In this research, we processed the GPS and meteorological data from about 220 stations of Crustal Movement Observation Network of China(CMONOC) observed in 2014 and derived the Zenith Total Delay(ZTD) map in both spat...In this research, we processed the GPS and meteorological data from about 220 stations of Crustal Movement Observation Network of China(CMONOC) observed in 2014 and derived the Zenith Total Delay(ZTD) map in both spatial and temporal dimension. The results of ZTD have high accurate and reliable as IGS and all sites with varying locations show obvious variety characteristics of Chinese mainland. Meanwhile, the precipitable water vapor(PWV) correlation coefficients between GPS observation and upper air sounding is close to 1, and the comparison of GPS-derived PWV and observed PWV from meteorological sites indicating GPS observation data generated in CMONOC project applied to the weather forecast research is feasible. In addition, based on all stations covered the whole Chinese land area and using interpolation algorithms, we make contour plots of PWV distribution per hour. We observe obvious feature that the precipitable water in north and western area is less than south and east area all over this year. High latitudes area may be dry and low latitudes area is wet.展开更多
Four Zr–Cu–Fe–Al-based bulk metallic glasses（BMGs） with Zr contents greater than 65at% and minor additions of Nb were designed and prepared. The glass forming abilities, thermal stabilities, mechanical properties...Four Zr–Cu–Fe–Al-based bulk metallic glasses（BMGs） with Zr contents greater than 65at% and minor additions of Nb were designed and prepared. The glass forming abilities, thermal stabilities, mechanical properties, and corrosion resistance properties of the prepared BMGs were investigated. These BMGs exhibit moderate glass forming abilities along with superior fracture and yield strengths compared to previously reported Zr–Cu–Fe–Al BMGs. Specifically, the addition of Nb into this quaternary system remarkably increases the plastic strain to 27.5%, which is related to the high Poisson＇s ratio and low Young＇s and shear moduli. The Nb-bearing BMGs also exhibit a lower corrosion current density by about one order of magnitude and a wider passive region than 316 L steel in phosphate buffer solution（PBS, pH 7.4）. The combination of the optimized composition with high deformation ability, low Young＇s modulus, and excellent corrosion resistance properties indicates that this kind of BMG is promising for biomedical applications.展开更多
Perovskite solar cells(PSCs)are becoming a promising candidate for next-generation photovoltaic cells due to their attractive power conversion efficiency(PCE).Plasmonic enhancement is regarded as an optical tuning app...Perovskite solar cells(PSCs)are becoming a promising candidate for next-generation photovoltaic cells due to their attractive power conversion efficiency(PCE).Plasmonic enhancement is regarded as an optical tuning approach for further improving the PCE of single-junction PSCs toward Shockley-Queisser limit.Herein,we introduce molecularly isolated gold nanorods(Au NRs),bearing relatively stronger scattering ability and localized surface plasmonic resonance(LSPR)effect,in the rear side of perovskites in PSCs,for promoting light harvesting and for electrical enhancement.Owing to the larger refractive index and better matched energy level alignment,the 4-mercaptobenzoic acid molecules coated on Au NRs prove to play important dual roles:isolating the metallic Au NRs from contacting with perovskite,and facilitating more efficient charge separation and transport across the interface under the synergetic LSPR effect of Au NRs.Our work highlights the capability of the plasmonic approach by nanorods and by molecular isolation,extending nanoparticle-based plasmonic approaches,toward highly efficient plasmon-enhanced PSCs.展开更多
The influences of reducing the supply voltage on single event upset(SEU) and multiple-cell upset(MCU) in two kinds of 65-nm static random access memories(SRAMs) are characterized across a wide linear energy transfer(L...The influences of reducing the supply voltage on single event upset(SEU) and multiple-cell upset(MCU) in two kinds of 65-nm static random access memories(SRAMs) are characterized across a wide linear energy transfer(LET) range.The results show that the influence of the voltage variation on SEU cross section clearly depends on the LET value which is above heavy ion LET threshold no matter whether the SRAM is non-hardened 6 T SRAM or radiation-hardened double dual interlocked cells(DICE) SRAM.When the LET value is lower than the LET threshold of MCU,the SEU only manifests single cell upset,the SEU cross section increases with the decrease of voltage.The lower the LET value,the higher the SEU sensitivity to the voltage variation is.Lowering the voltage has no evident influence on SEU cross section while the LET value is above the LET threshold of MCU.Moreover,the reduction of the voltage can result in a decrease in the highest-order MCU event cross section due to the decrease of charge collection efficiency of the outer sub-sensitive volume within a certain voltage range.With further scaling the feature size of devices down,it is suggested that the dependence of SEU on voltage variation should be paid special attention to for heavy ions with very low LET or the other particles with very low energy for nanometer commercial off-the-shelf(COTS) SRAM.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 11690040 and 11690043)。
文摘Machine learning-based surrogate models have significant advantages in terms of computing efficiency. In this paper, we present a pilot study on fast calibration using machine learning techniques. Technology computer-aided design(TCAD) is a powerful simulation tool for electronic devices. This simulation tool has been widely used in the research of radiation effects.However, calibration of TCAD models is time-consuming. In this study, we introduce a fast calibration approach for TCAD model calibration of metal–oxide–semiconductor field-effect transistors(MOSFETs). This approach utilized a machine learning-based surrogate model that was several orders of magnitude faster than the original TCAD simulation. The desired calibration results were obtained within several seconds. In this study, a fundamental model containing 26 parameters is introduced to represent the typical structure of a MOSFET. Classifications were developed to improve the efficiency of the training sample generation. Feature selection techniques were employed to identify important parameters. A surrogate model consisting of a classifier and a regressor was built. A calibration procedure based on the surrogate model was proposed and tested with three calibration goals. Our work demonstrates the feasibility of machine learning-based fast model calibrations for MOSFET. In addition, this study shows that these machine learning techniques learn patterns and correlations from data instead of employing domain expertise. This indicates that machine learning could be an alternative research approach to complement classical physics-based research.
基金supported by the National Natural Science Foundation of China (22179007)。
文摘To obtain high-performance lithium-sulfur(Li-S)batteries,it is necessary to rationally design electrocatalytic materials that can promote efficient sulfur electrochemical reactions.Herein,the robust heterostructured material of nanoscale transition metal anchored on perovskite oxide was designed for efficient catalytic kinetics of the oxidation and reduction reactions of lithium polysulphide(Li PSs),and verified by density functional theory(DFT)calculations and experimental characterizations.Due to the strong interaction of nanoscale transition metals with Li PSs through chemical coupling,heterostructured materials(STO@M)(M=Fe,Ni,Cu)exhibit excellent catalytic activity for redox reactions of Li PSs.The bifunctional heterostructure material STO@Fe exhibits good rate performance and cycling stability as the cathode host,realizing a high-performance Li-S battery that can maintain stable cycling under rapid charge-discharge cycling.This study presents a novel approach to designing electrocatalytic materials for redox reactions of Li PSs,which promotes the development of fast charge-discharge Li-S batteries.
基金supported by Provincial Natural Science Foundation of Hainan(Grant number 811214)Provincial Higher School Scientific Research Project of Hainan(Grant number Hjkj2011-35)was provided by Department of Neurology,Affiliated Hospital of Hainan Medical College
文摘Objective::To investigate the neuroprotective effects of simvastatin on lipopolysaccharide(LPS)-indueed rat model of Parkinson's disease(PD) and the mechanisms involved.Methods:Hemiparkinsonian rat models were induced by stereotaxieal injection of LPS in the right substantia nigra compacts.After 2 weeks of simvastatin treatment,rotational behavior test was performed after the intraperitoneal injection of apomorphine.Expression of tyroxine hydroxylase(TH) and glial fibrillan acidic protein were analyzed through immunohistochemical staining of substantia nigra and striatum,and the level of TNF-α was evaluated using enzyme-linked immunosorbent assay.Results:Comparing with untreated group,behavioral symptoms of the rats were significantly less in the rats that received simvastatin treatment.The TH positive cell count in substantia nigra and striatum were significantly increased(P<0.05) and TNF- α expression was significantly decreased(P<0.05) in simvastatin group compared to untreated group.Conclusions:Simvastatin could effectively inhibit the activation of astrocytes,reduce TNF-α expression,and exert anti-inflammatory effects,and thus protect the dopaminergic neurons in substantia nigra and striatum of the rat model of PD.
基金National Natural Science Foundation of China,No.81701058Shandong Academy of Sciences,No.ZR2017PH027and China Postdoctoral Science Foundation,No.2017M612288.
文摘BACKGROUND Thallium poisoning is rare and difficult to recognize.Early diagnosis and treatment of thallium-poisoned patients are essential to prevent morbidity and mortality.AIM To evaluate the efficacy of treatments and outcomes of five patients with early diagnosis of acute thallium poisoning.METHODS Five patients who consumed a thallium-contaminated meal were hospitalized in succession,and underwent clinical examinations such as blood tests and electromyography tests.Urine and blood tests confirmed the diagnosis of thallotoxicosis,revealing the occurrence of food poisoning.All patients underwent detoxification treatment,including hemoperfusion(HP)and treatment with Prussian blue(PB).A 24-mo follow-up was performed to evaluate the long-term outcomes on the patients after discharge.RESULTS Initially,the patients presented with symptoms of acute thallium poisoning including hyperalgesia of the limbs and abdominalgia,which may differ from common peripheral neuropathy.Accompanying symptoms such as hepatic damage and alopecia were observed in all the patients,which further confirmed the diagnosis of poisoning.Treatment with chelating agents was ineffective,while HP and treatment with PB drastically decreased the thallium concentration in the urine and blood.With early diagnosis and intervention,four patients had a good prognosis and no permanent sequelae.One patient developed blindness and disability during the 24-mo follow-up period.CONCLUSION Identification of incident cluster and characteristic symptoms is extremely important for early diagnosis of acute thallium poisoning.HP plus PB is essential to improve the prognosis of thallium-poisoned patients.
文摘In this research, we processed the GPS and meteorological data from about 220 stations of Crustal Movement Observation Network of China(CMONOC) observed in 2014 and derived the Zenith Total Delay(ZTD) map in both spatial and temporal dimension. The results of ZTD have high accurate and reliable as IGS and all sites with varying locations show obvious variety characteristics of Chinese mainland. Meanwhile, the precipitable water vapor(PWV) correlation coefficients between GPS observation and upper air sounding is close to 1, and the comparison of GPS-derived PWV and observed PWV from meteorological sites indicating GPS observation data generated in CMONOC project applied to the weather forecast research is feasible. In addition, based on all stations covered the whole Chinese land area and using interpolation algorithms, we make contour plots of PWV distribution per hour. We observe obvious feature that the precipitable water in north and western area is less than south and east area all over this year. High latitudes area may be dry and low latitudes area is wet.
基金financially supported by the National Natural Science Foundation of China (No. 51271018)the Proprietary Program of the State Key Laboratory for Advanced Metals and Materials,University of Science and Technology Beijing (Nos.2011Z-01 and 2012Z-01)
文摘Four Zr–Cu–Fe–Al-based bulk metallic glasses（BMGs） with Zr contents greater than 65at% and minor additions of Nb were designed and prepared. The glass forming abilities, thermal stabilities, mechanical properties, and corrosion resistance properties of the prepared BMGs were investigated. These BMGs exhibit moderate glass forming abilities along with superior fracture and yield strengths compared to previously reported Zr–Cu–Fe–Al BMGs. Specifically, the addition of Nb into this quaternary system remarkably increases the plastic strain to 27.5%, which is related to the high Poisson＇s ratio and low Young＇s and shear moduli. The Nb-bearing BMGs also exhibit a lower corrosion current density by about one order of magnitude and a wider passive region than 316 L steel in phosphate buffer solution（PBS, pH 7.4）. The combination of the optimized composition with high deformation ability, low Young＇s modulus, and excellent corrosion resistance properties indicates that this kind of BMG is promising for biomedical applications.
基金supported by the Ministry of Science and Technology of China(2016YFA0200703)the National Natural Science Foundation of China(21931009)。
文摘Perovskite solar cells(PSCs)are becoming a promising candidate for next-generation photovoltaic cells due to their attractive power conversion efficiency(PCE).Plasmonic enhancement is regarded as an optical tuning approach for further improving the PCE of single-junction PSCs toward Shockley-Queisser limit.Herein,we introduce molecularly isolated gold nanorods(Au NRs),bearing relatively stronger scattering ability and localized surface plasmonic resonance(LSPR)effect,in the rear side of perovskites in PSCs,for promoting light harvesting and for electrical enhancement.Owing to the larger refractive index and better matched energy level alignment,the 4-mercaptobenzoic acid molecules coated on Au NRs prove to play important dual roles:isolating the metallic Au NRs from contacting with perovskite,and facilitating more efficient charge separation and transport across the interface under the synergetic LSPR effect of Au NRs.Our work highlights the capability of the plasmonic approach by nanorods and by molecular isolation,extending nanoparticle-based plasmonic approaches,toward highly efficient plasmon-enhanced PSCs.
基金Project supported by the Major Program of the National Natural Science Foundation of China(Grant Nos.11690043 and 11690040)。
文摘The influences of reducing the supply voltage on single event upset(SEU) and multiple-cell upset(MCU) in two kinds of 65-nm static random access memories(SRAMs) are characterized across a wide linear energy transfer(LET) range.The results show that the influence of the voltage variation on SEU cross section clearly depends on the LET value which is above heavy ion LET threshold no matter whether the SRAM is non-hardened 6 T SRAM or radiation-hardened double dual interlocked cells(DICE) SRAM.When the LET value is lower than the LET threshold of MCU,the SEU only manifests single cell upset,the SEU cross section increases with the decrease of voltage.The lower the LET value,the higher the SEU sensitivity to the voltage variation is.Lowering the voltage has no evident influence on SEU cross section while the LET value is above the LET threshold of MCU.Moreover,the reduction of the voltage can result in a decrease in the highest-order MCU event cross section due to the decrease of charge collection efficiency of the outer sub-sensitive volume within a certain voltage range.With further scaling the feature size of devices down,it is suggested that the dependence of SEU on voltage variation should be paid special attention to for heavy ions with very low LET or the other particles with very low energy for nanometer commercial off-the-shelf(COTS) SRAM.
