High-entropy perovskite ferroelectric materials have attracted significant attention due to their remarkably low remnant polarizations and narrow hysteresis.Thus,these materials offer high-energy density and efficienc...High-entropy perovskite ferroelectric materials have attracted significant attention due to their remarkably low remnant polarizations and narrow hysteresis.Thus,these materials offer high-energy density and efficiency,making them suitable for energy storage applications.Despite significant advancements in experimental research,understanding of the properties associated with structure remains incomplete.This study aims to study the structural,electric,and mechanical performances at various scales of the high-entropy(Na_(0.2)Bi_(0.2)Ca_(0.2)Sr_(0.2)Ba_(0.2))TiO_(3)(NBCSB)material.The results of first-principles calculations indicated that the pseudo-intralayer distortion was obviously smaller compared to the interlayer distortion.Among the various bonds,Bi-O,Ca-O,and Na-O experienced the greatest displacement.Similarly,the hybridization between O 2p and Ti 3d states with Bi 6p states was particularly strong,affecting both the ferroelectric polarization and relaxor behavior.The NBCSB materials produced using a typical solid-state process demonstrated exceptional performance in energy storage with a recoverable density of 1.53 J·cm^(-3)and a high efficiency of 89%when subjected to a small electric field of 120 kV·cm^(-1).In addition,these ceramics displayed a remarkable hardness of around 7.23 GPa.NBCSB ceramics exhibited exceptional relaxation characteristics with minimal hysteresis and low remanent polarization due to its nanoscale high dynamic polarization configuration with diverse symmetries(rhombohedral,tetragonal,and cubic)resulting from randomly dispersed A-site ions.The excellent mechanical property is related to the dislocation-blocking effect,solid solution strengthening effect,and domain boundary effect.The findings of this study offer a comprehensive and novel perspective on A-site disordered high-entropy relaxor ferroelectric ceramics.展开更多
Severe influenza infections are often associated with the excessive induction of pro-inflammatory cytokines,which is also referred to as"cytokine storms".Several studies have shown that cytokine storms are d...Severe influenza infections are often associated with the excessive induction of pro-inflammatory cytokines,which is also referred to as"cytokine storms".Several studies have shown that cytokine storms are directly associated with influenzainduced fatal acute lung injury and acute respiratory distress syndrome.Due to the narrow administration window,current antiviral therapies are often inadequate.The efforts to use immunomodulatory agents alone or in combination with antiviral agents in the treatment of influenza in animal models have resulted in the achievement of protective effects accompanied with reduced cytokine production.Currently,there are no immunomodulatory drugs for influenza available for clinical use.Animal models,despite being ideal to study the anti-inflammatory responses to influenza virus infection,are very costly and time-consuming.Therefore,there is an urgent need to establish fast and economical screening methods using cellbased models to screen and develop novel immunomodulatory agents.In this study,we screened seven human cell lines and found that the human monocytic cell U937 supports the replication of different subtypes of influenza viruses as well as the production of the important pro-inflammatory cytokines and was selected to develop the cell-based model.The U937 cell model was validated by testing a panel of known antiviral and immunomodulatory agents and screening a drug library consisting of 1280 compounds comprised mostly of FDA-approved drugs.We demonstrated that the U937 cell model is robust and suitable for the high-throughput screening of immunomodulators and antivirals against influenza infection.展开更多
目的探究不同水平呼气末正压(PEEP)治疗新生儿急性呼吸窘迫综合征(ARDS)的疗效及其血流动力学影响。方法选取2017年3月—2019年5月天津市中心妇产科医院收治的112例ARDS新生儿。根据通气的不同分为研究组和对照组,研究组58例患儿接受高...目的探究不同水平呼气末正压(PEEP)治疗新生儿急性呼吸窘迫综合征(ARDS)的疗效及其血流动力学影响。方法选取2017年3月—2019年5月天津市中心妇产科医院收治的112例ARDS新生儿。根据通气的不同分为研究组和对照组,研究组58例患儿接受高水平PEEP(6~<9 cm H2O)治疗,对照组54例患儿接受低水平PEEP(3~<6 cm H2O)治疗。观察两组患者治疗前及治疗稳定后24 h的心率(HR)、平均肺动脉压(MPAP)、中心静脉压(CVP)、pH值、动脉血二氧化碳分压(PaCO2)、氧合指数(OI)水平、气道阻力(Raw)、呼吸系统顺应性(Crs)。观察两组患者的机械通气时间、住院时间、死亡例数。结果研究组HR、MPAP降低的差值,以及CVP升高的差值均高于对照组(P<0.05);研究组pH值、OI升高的差值,以及PaCO2降低的差值均高于对照组(P<0.05);研究组Raw降低的差值及Crs升高的差值均高于对照组(P<0.05)。研究组机械通气时间、住院时间均短于对照组(P<0.05);研究组死亡率低于对照组(P<0.05)。结论高水平PEEP对新生儿血流动力学指标的改善作用更明显,对气体交换和呼吸力学的影响更大,能有效减少机械通气时间及住院时间,降低病死率。展开更多
In this work,a simple two-step electrodeposition was employed to prepare PPy-Cu/GF(PPy,polypyrrole;GF,graphite felt)composite cathodes for the nitrate reduction.Characterized results revealed that the introduction of ...In this work,a simple two-step electrodeposition was employed to prepare PPy-Cu/GF(PPy,polypyrrole;GF,graphite felt)composite cathodes for the nitrate reduction.Characterized results revealed that the introduction of PPy as an intermediate layer resulted in the transformation of both granular and dendritic Cu in form of Cu^(+)/Cu^(0),Cu^(2+)on the electrode surface.The NO_(3)^(-)-N of 50 mg·L^(-1)was almost completely removed(99.01%)using the PPy-Cu/GF cathode under the optimum condition,which is obviously higher than the GF,PPy/GF and Cu/GF electrodes.NO_(3)^(-)-N removal was slightly affected over the pH scale of 3.0 e11.0,whereas increasing the current density from 10 to 25 mA·cm^(-2)boosted the reduction of NO_(3)^(-)-N.At a Cl-concentration of 2000 mg·L^(-1),the removal of NO_(3)^(-)-N was slightly reduced,while the selectivity for N_(2)increased dramatically due to the active chlorine could oxidize NH_(4)^(+)-N to N_(2).Meanwhile,PPy-Cu/GF cathode exhibits an average removal rate of 97.83%within 12 cycles,highlighting its potential for application in actual water bodies.The EPR analysis and the active species trapping experiment confirmed that the nitrate reduction on the PPy-Cu/GF cathode mainly relies on direct reduction mediated by electron transfer,while*H influences the reduction of nitrite to ammonia.展开更多
我国农村地区黑臭水体广泛存在,利用遥感技术对其进行监测的研究刚刚起步,许多技术性问题亟待解决。在吉林省、云南省和广西农村地区进行样品采集,于2021~2022年期间,共收集75个黑臭水体水样和85个一般水体水样,分别对其水质参数以及光...我国农村地区黑臭水体广泛存在,利用遥感技术对其进行监测的研究刚刚起步,许多技术性问题亟待解决。在吉林省、云南省和广西农村地区进行样品采集,于2021~2022年期间,共收集75个黑臭水体水样和85个一般水体水样,分别对其水质参数以及光学特性进行分析。以高分二号为数据源,分析黑臭水体与一般水体的影像光谱特征,发现农村黑臭水体反射率在红波段以及近红外波段有上升的趋势,红、绿波段的反射率很低且差值小,根据这两个黑臭水体典型的光谱特征,构建了一种新的黑臭水体识别指数MBOI(Multi-spectral Black and Odorous Water Index),识别精度较高。主要研究结果如下:(1)黑臭水体与一般水体相比,其具有较高的总悬浮颗粒物浓度,黑臭水体有机碳的浓度是一般水体有机碳浓度的1.82倍。(2)在440 nm处,黑臭水体中的水体组分吸收系数,即色素、非色素颗粒物以及有色可溶性有机物的吸收系数均高于一般水体。(3)利用去瑞利校正后的影像光谱反射率数据进行数据建模与模型验证,当MBOI取值在0~0.18之间时,判定为黑臭水体,模型精度满足黑臭水体识别的要求。展开更多
Objectives:This study aimed to explore the status of job satisfaction,emotional labour,core competencies and job stress and the associations of emotional labour and core competencies with the job satisfaction of nurse...Objectives:This study aimed to explore the status of job satisfaction,emotional labour,core competencies and job stress and the associations of emotional labour and core competencies with the job satisfaction of nurses in China.Methods:Data were collected by using a self-designed general information questionnaire,a job satisfaction questionnaire(McCloskey/Mueller Satisfaction Scale),a nurse emotional labour questionnaire,the Competency Inventory for Registered Nurses questionnaire,and a nurse job stressor questionnaire.A total of 13,448 nurses from 92 hospitals across mainland of China were surveyed,and 11,337 respondents(84.3%response rate)completed the questionnaires.Results:The survey results indicated that Chinese nurses had average job satisfaction(24.77±5.23),moderate job stress(86.84±21.12),moderate to high emotional labour experiences(55.08±9.63)and high competency(195.77±37.61).Multiple linear regression indicated that surface acting was negatively correlated with job satisfaction(P<0.01),while deep acting(P<0.01)and nurses'core competence(P<0.01)were positively associated with job satisfaction.Besides,The results also indicated job stress,geographical distribution,hospital category,gender,work shift,only children,parenting status,monthly salary,nursing experience,professional title,hospital area were the influencing factors of job satisfaction(P<0.05).Conclusion:The improvement of the emotional labour and competency of nurses may help enhance their job satisfaction.展开更多
The variation in the precipitation phase in polar regions represents an important indicator of climate change and variability.We studied the precipitation phase at the Great Wall Station and Antarctic Peninsula(AP)reg...The variation in the precipitation phase in polar regions represents an important indicator of climate change and variability.We studied the precipitation phase at the Great Wall Station and Antarctic Peninsula(AP)region,based on daily precipitation,synoptic records and ERA-Interim data during the austral summers of 1985?2014.Overall,there was no trend in the total precipitation amount or days,but the phase of summer precipitation(rainfall days versus snowfall days)showed opposite trends before and after 2001 at the AP.The total summer rain days/snow days increased/decreased during 1985?2001 and significantly decreased at a rate of?14.13 d(10 yr)?1/increased at a rate of 14.31 d(10 yr)?1 during 2001?2014,agreeing well with corresponding variations in the surface air temperature.Further,we found that the longitudinal location of the Amundsen Sea low(ASL)should account for the change in the precipitation phase since 2001,as it has shown a westward drift after 2001[?41.1°(10 yr)?1],leading to stronger cold southerly winds,colder water vapor flux,and more snow over the AP region during summertime.This study points out a supplementary factor for the climate variation on the AP.展开更多
The prediction of summer precipitation over the Yangtze River basin(YRB)has long been challenging,especially during June-July(JJ),when the mei-yu generally occurs.This study explores the potential signal for the YRB p...The prediction of summer precipitation over the Yangtze River basin(YRB)has long been challenging,especially during June-July(JJ),when the mei-yu generally occurs.This study explores the potential signal for the YRB precipitation in JJ and reveals that the Tibetan Plateau tropospheric temperature(TPTT)in the middle and upper levels during the preceding December-January(DJ)is significantly correlated with JJ YRB precipitation.The close connection between the DJ TPTT anomaly with JJ YRB precipitation may be due to the joint modulation of the DJ ENSO and spring TP soil temperatures.The lagged response to an anomalously cold TPTT during the preceding DJ is a TPTT that is still anomalously cold during the following JJ.The lower TPTT can lead to an anomalous anticyclone to the east of Lake Baikal,an anomalous cyclone at the middle latitudes of East Asia,and an anomalous anticyclone over the western North Pacific.Meanwhile,the East Asian westerly jet shifts southward in response to the meridional thermal gradient caused by the colder troposphere extending from the TP to the east of Lake Baikal.The above-mentioned circulation anomalies constitute the positive anomaly of the East Asia-Pacific pattern,known to be conducive to more precipitation over the YRB.Since the DJ TPTT contains both the land(TP soil temperature)and ocean(ENSO)signals,it has a closer relationship with the JJ precipitation over the YRB than the DJ ENSO alone.Therefore,the preceding DJ TPTT can be considered an alternative predictor of the JJ YRB precipitation.展开更多
In terahertz communication,the direct frequency conversion structure in which orthogonal mixer is the main frequency conversion unit,makes engineers get into trouble of in-phase(I)branch and quadrature(Q)branch imbala...In terahertz communication,the direct frequency conversion structure in which orthogonal mixer is the main frequency conversion unit,makes engineers get into trouble of in-phase(I)branch and quadrature(Q)branch imbalance,carrier wave leakage,etc.These damages result in system performance tremendous degrades.We proposed a semiblind method to estimate the I/Q imbalance of THz orthogonal modulator,based on predefined preamble and pilot symbols for quadrature amplitude modulation(QAM).In this paper,a transmitter with Y band quadrature mixer and 20Gbps base-band signal has been tested.The bandwidth of the baseband signal was 7GHz,and the modulation type was 16QAM.By this method,7dB improvement of the system’s symbol Mean Square Error(MSE)has been got.That means the proposed method can be used to eliminate the I/Q imbalance effectively.展开更多
Pulsed metal organic chemical vapor deposition was employed to grow nearly polarization matched InAlGaN/GaN heterostructures.A relatively low sheet carrier density of 1.8×10^(12)cm^(-2),together with a high elect...Pulsed metal organic chemical vapor deposition was employed to grow nearly polarization matched InAlGaN/GaN heterostructures.A relatively low sheet carrier density of 1.8×10^(12)cm^(-2),together with a high electron mobility of 1229.5 cm^2/V·s,was obtained for the prepared heterostructures.The surface morphology of the heterostructures was also significantly improved,i.e.,with a root mean square roughness of 0.29 nm in a 2μm×2μm scan area.In addition to the improved properties,the enhancement-mode metal–oxide–semiconductor high electron mobility transistors(MOSHEMTs)processed on the heterostructures not only exhibited a high threshold voltage(VTH)of 3.1 V,but also demonstrated a significantly enhanced drain output current density of 669 m A/mm.These values probably represent the largest values obtained from the InAlGaN based enhancement-mode devices to the best of our knowledge.This study strongly indicates that the InAlGaN/GaN heterostructures grown by pulsed metal organic chemical vapor deposition could be promising for the applications of novel nitride-based electronic devices.展开更多
A functional model named EIO(Errors-In-Observations) is proposed for general TLS(total least-squares)adjustment. The EIO model only considers the correction of the observation vector, but doesn't consider to corre...A functional model named EIO(Errors-In-Observations) is proposed for general TLS(total least-squares)adjustment. The EIO model only considers the correction of the observation vector, but doesn't consider to correct all elements in the design matrix as the EIV(Errors-In-Variables) model does, furthermore, the dimension of cofactor matrix is much smaller. Iterative algorithms for the parameter estimation and their precise covariance matrix are derived rigorously, and the computation steps are also presented. The proposed approach considers the correction of the observations in the coefficient matrix, and ensures their agreements in every matrix elements. Parameters and corrections can be solved at the same time.An approximate solution and a precise solution of the covariance matrix can be achieved by corresponding algorithms. Applications of EIO model and the proposed algorithms are demonstrated with several examples. The results and comparative studies show that the proposed EIO model and algorithms are feasible and reliable for general adjustment problems.展开更多
The investigation concentrates on friction stir welded(FSW)Al-Cu-Li alloy concerning its local microstructural evolution and mechanical properties.The grain features were characterized by electron back scattered diffr...The investigation concentrates on friction stir welded(FSW)Al-Cu-Li alloy concerning its local microstructural evolution and mechanical properties.The grain features were characterized by electron back scattered diffraction(EBSD)technology,while precipitate characterization was conducted by using transmission electron microscopy(TEM)aligned along[011]Al and[001]Al zone axes.The mechanical properties are evaluated through micro-hardness and tensile testing.It can be found that nugget zones exhibit finely equiaxed grains evolved through complete dynamic recrystallization(DRX),primarily occurring in continuous dynamic recrystallization(CDRX)and discontinuous dynamic recrystallization(DDRX).In the thermal-mechanically affected zone(TMAZ),numerous sub-structured grains,exhibiting an elongated morphology,were created due to partial DRX,signifying the dominance of CDRX,DDRX,and geometric dynamic recrystallization(GDRX)in this region.T_(1)completely dissolves in the nugget zone(NZ)leading to the formation of Guinier-Preston zones and increase ofδ′,β′and S′.Conversely,T_(1)partially solubilizes in TMAZ,the lowest hardness zone(LHZ)and heat affected zone(HAZ),and the residual T_(1)undergoes marked coarsening,revealing various T_(1)variants.The solubilization and coarsening of T_(1)are primary contributors to the degradation of hardness and strength.θ′primarily dissolves and coarsens in NZ and TMAZ,whilst this precipitate largely coarsens in HAZ and LHZ.σ,TB,grain boundary phases(GBPs)and precipitate-free zone(PFZ)are newly generated during FSW.σexists in the TMAZ,LHZ and HAZ,whereas TB nucleates in NZ.GBPs and PFZ mostly develop in LHZ and HAZ,which can cause strain localization during tensile deformation,potentially leading to LHZ joint fracture.展开更多
This paper presents the design and simulation of several fixed-tuned sub-harmonic mixers cover frequencies from 110 GH to 130 GHz, 215 GH to 235 GHz, 310 GH to 350 GHz, and 400 GH to 440 GHz. Among them, 120 GHz, 225 ...This paper presents the design and simulation of several fixed-tuned sub-harmonic mixers cover frequencies from 110 GH to 130 GHz, 215 GH to 235 GHz, 310 GH to 350 GHz, and 400 GH to 440 GHz. Among them, 120 GHz, 225 GHz, 330 GHz subharmonic mixers are designed with flip-chipped planar schottky diode mounted onto a suspended quartz-based substrate, the 225 GHz and 425 GHz subharmonic mixers are GaAs membrane integrated, and the 115 GHz subharmonic mixer has been fabricated and tested already.展开更多
基金supported by Guangdong Basic and Applied Basic Research Foundation and Project of General Colleges and Universities in Guangdong Province(Nos.2022A1515140002 and 2019GKQNCX127)the Special Innovation Projects of Department of Education’s of Guangdong Provincial(No.2018KTSCX220)+4 种基金the International Cooperation Project of Guangdong Province(No.2019A050510049)the Program for Innovative Research Team of Guangdong Province&Huizhou University(IRTHZU)Indigenous Innovation’s Capability Development Program of Huizhou University(No.HZU202014)the Open Project Program of Guangdong Provincial Key Laboratory of Electronic Functional Materials and Devices,Huizhou University(No.EFMD2022015M)the National Natural Science Foundation of China(No.12102068).
文摘High-entropy perovskite ferroelectric materials have attracted significant attention due to their remarkably low remnant polarizations and narrow hysteresis.Thus,these materials offer high-energy density and efficiency,making them suitable for energy storage applications.Despite significant advancements in experimental research,understanding of the properties associated with structure remains incomplete.This study aims to study the structural,electric,and mechanical performances at various scales of the high-entropy(Na_(0.2)Bi_(0.2)Ca_(0.2)Sr_(0.2)Ba_(0.2))TiO_(3)(NBCSB)material.The results of first-principles calculations indicated that the pseudo-intralayer distortion was obviously smaller compared to the interlayer distortion.Among the various bonds,Bi-O,Ca-O,and Na-O experienced the greatest displacement.Similarly,the hybridization between O 2p and Ti 3d states with Bi 6p states was particularly strong,affecting both the ferroelectric polarization and relaxor behavior.The NBCSB materials produced using a typical solid-state process demonstrated exceptional performance in energy storage with a recoverable density of 1.53 J·cm^(-3)and a high efficiency of 89%when subjected to a small electric field of 120 kV·cm^(-1).In addition,these ceramics displayed a remarkable hardness of around 7.23 GPa.NBCSB ceramics exhibited exceptional relaxation characteristics with minimal hysteresis and low remanent polarization due to its nanoscale high dynamic polarization configuration with diverse symmetries(rhombohedral,tetragonal,and cubic)resulting from randomly dispersed A-site ions.The excellent mechanical property is related to the dislocation-blocking effect,solid solution strengthening effect,and domain boundary effect.The findings of this study offer a comprehensive and novel perspective on A-site disordered high-entropy relaxor ferroelectric ceramics.
基金supported by the Important Hubei Science and Technology Innovation Plan 2015ACA062 (to Xulin Chen)the Natural Science Foundation of Hubei Province (2018CFB244, to Jungang Chen)
文摘Severe influenza infections are often associated with the excessive induction of pro-inflammatory cytokines,which is also referred to as"cytokine storms".Several studies have shown that cytokine storms are directly associated with influenzainduced fatal acute lung injury and acute respiratory distress syndrome.Due to the narrow administration window,current antiviral therapies are often inadequate.The efforts to use immunomodulatory agents alone or in combination with antiviral agents in the treatment of influenza in animal models have resulted in the achievement of protective effects accompanied with reduced cytokine production.Currently,there are no immunomodulatory drugs for influenza available for clinical use.Animal models,despite being ideal to study the anti-inflammatory responses to influenza virus infection,are very costly and time-consuming.Therefore,there is an urgent need to establish fast and economical screening methods using cellbased models to screen and develop novel immunomodulatory agents.In this study,we screened seven human cell lines and found that the human monocytic cell U937 supports the replication of different subtypes of influenza viruses as well as the production of the important pro-inflammatory cytokines and was selected to develop the cell-based model.The U937 cell model was validated by testing a panel of known antiviral and immunomodulatory agents and screening a drug library consisting of 1280 compounds comprised mostly of FDA-approved drugs.We demonstrated that the U937 cell model is robust and suitable for the high-throughput screening of immunomodulators and antivirals against influenza infection.
文摘目的探究不同水平呼气末正压(PEEP)治疗新生儿急性呼吸窘迫综合征(ARDS)的疗效及其血流动力学影响。方法选取2017年3月—2019年5月天津市中心妇产科医院收治的112例ARDS新生儿。根据通气的不同分为研究组和对照组,研究组58例患儿接受高水平PEEP(6~<9 cm H2O)治疗,对照组54例患儿接受低水平PEEP(3~<6 cm H2O)治疗。观察两组患者治疗前及治疗稳定后24 h的心率(HR)、平均肺动脉压(MPAP)、中心静脉压(CVP)、pH值、动脉血二氧化碳分压(PaCO2)、氧合指数(OI)水平、气道阻力(Raw)、呼吸系统顺应性(Crs)。观察两组患者的机械通气时间、住院时间、死亡例数。结果研究组HR、MPAP降低的差值,以及CVP升高的差值均高于对照组(P<0.05);研究组pH值、OI升高的差值,以及PaCO2降低的差值均高于对照组(P<0.05);研究组Raw降低的差值及Crs升高的差值均高于对照组(P<0.05)。研究组机械通气时间、住院时间均短于对照组(P<0.05);研究组死亡率低于对照组(P<0.05)。结论高水平PEEP对新生儿血流动力学指标的改善作用更明显,对气体交换和呼吸力学的影响更大,能有效减少机械通气时间及住院时间,降低病死率。
基金supported by the National Natural Science Foundation of China(22076111)Key Research and Development Program of Shaanxi(2024 GX-YBXM-427),China.
文摘In this work,a simple two-step electrodeposition was employed to prepare PPy-Cu/GF(PPy,polypyrrole;GF,graphite felt)composite cathodes for the nitrate reduction.Characterized results revealed that the introduction of PPy as an intermediate layer resulted in the transformation of both granular and dendritic Cu in form of Cu^(+)/Cu^(0),Cu^(2+)on the electrode surface.The NO_(3)^(-)-N of 50 mg·L^(-1)was almost completely removed(99.01%)using the PPy-Cu/GF cathode under the optimum condition,which is obviously higher than the GF,PPy/GF and Cu/GF electrodes.NO_(3)^(-)-N removal was slightly affected over the pH scale of 3.0 e11.0,whereas increasing the current density from 10 to 25 mA·cm^(-2)boosted the reduction of NO_(3)^(-)-N.At a Cl-concentration of 2000 mg·L^(-1),the removal of NO_(3)^(-)-N was slightly reduced,while the selectivity for N_(2)increased dramatically due to the active chlorine could oxidize NH_(4)^(+)-N to N_(2).Meanwhile,PPy-Cu/GF cathode exhibits an average removal rate of 97.83%within 12 cycles,highlighting its potential for application in actual water bodies.The EPR analysis and the active species trapping experiment confirmed that the nitrate reduction on the PPy-Cu/GF cathode mainly relies on direct reduction mediated by electron transfer,while*H influences the reduction of nitrite to ammonia.
文摘我国农村地区黑臭水体广泛存在,利用遥感技术对其进行监测的研究刚刚起步,许多技术性问题亟待解决。在吉林省、云南省和广西农村地区进行样品采集,于2021~2022年期间,共收集75个黑臭水体水样和85个一般水体水样,分别对其水质参数以及光学特性进行分析。以高分二号为数据源,分析黑臭水体与一般水体的影像光谱特征,发现农村黑臭水体反射率在红波段以及近红外波段有上升的趋势,红、绿波段的反射率很低且差值小,根据这两个黑臭水体典型的光谱特征,构建了一种新的黑臭水体识别指数MBOI(Multi-spectral Black and Odorous Water Index),识别精度较高。主要研究结果如下:(1)黑臭水体与一般水体相比,其具有较高的总悬浮颗粒物浓度,黑臭水体有机碳的浓度是一般水体有机碳浓度的1.82倍。(2)在440 nm处,黑臭水体中的水体组分吸收系数,即色素、非色素颗粒物以及有色可溶性有机物的吸收系数均高于一般水体。(3)利用去瑞利校正后的影像光谱反射率数据进行数据建模与模型验证,当MBOI取值在0~0.18之间时,判定为黑臭水体,模型精度满足黑臭水体识别的要求。
文摘Objectives:This study aimed to explore the status of job satisfaction,emotional labour,core competencies and job stress and the associations of emotional labour and core competencies with the job satisfaction of nurses in China.Methods:Data were collected by using a self-designed general information questionnaire,a job satisfaction questionnaire(McCloskey/Mueller Satisfaction Scale),a nurse emotional labour questionnaire,the Competency Inventory for Registered Nurses questionnaire,and a nurse job stressor questionnaire.A total of 13,448 nurses from 92 hospitals across mainland of China were surveyed,and 11,337 respondents(84.3%response rate)completed the questionnaires.Results:The survey results indicated that Chinese nurses had average job satisfaction(24.77±5.23),moderate job stress(86.84±21.12),moderate to high emotional labour experiences(55.08±9.63)and high competency(195.77±37.61).Multiple linear regression indicated that surface acting was negatively correlated with job satisfaction(P<0.01),while deep acting(P<0.01)and nurses'core competence(P<0.01)were positively associated with job satisfaction.Besides,The results also indicated job stress,geographical distribution,hospital category,gender,work shift,only children,parenting status,monthly salary,nursing experience,professional title,hospital area were the influencing factors of job satisfaction(P<0.05).Conclusion:The improvement of the emotional labour and competency of nurses may help enhance their job satisfaction.
基金Project supported by the National Research Program for High Technology Ship Development of China(No.MIIT 2014-498)the Science and Technology of Guangdong Province,China(Nos2015B090904010 and 2016B090918092)+3 种基金the Marine Renewable Energy Special Fund of China(No.QDME2013ZB01)the Nationa Natural Science Foundation of China(No.51609036)the Funda mental Research Funds for the Central Universities of China(No DUT16RC(4)26)the Doctoral Scientific Research Foundation o Liaoning Province,China(No.201501176)
基金Strategic Priority Research Program of Chinese Academy of Sciences(XDA20100300)the National Natural Science Foundation of China(Grant No.41771064)the Basic Fund of the Chinese Academy of Meteorological Sciences(Grant Nos.2018Z001 and 2019Z008).
文摘The variation in the precipitation phase in polar regions represents an important indicator of climate change and variability.We studied the precipitation phase at the Great Wall Station and Antarctic Peninsula(AP)region,based on daily precipitation,synoptic records and ERA-Interim data during the austral summers of 1985?2014.Overall,there was no trend in the total precipitation amount or days,but the phase of summer precipitation(rainfall days versus snowfall days)showed opposite trends before and after 2001 at the AP.The total summer rain days/snow days increased/decreased during 1985?2001 and significantly decreased at a rate of?14.13 d(10 yr)?1/increased at a rate of 14.31 d(10 yr)?1 during 2001?2014,agreeing well with corresponding variations in the surface air temperature.Further,we found that the longitudinal location of the Amundsen Sea low(ASL)should account for the change in the precipitation phase since 2001,as it has shown a westward drift after 2001[?41.1°(10 yr)?1],leading to stronger cold southerly winds,colder water vapor flux,and more snow over the AP region during summertime.This study points out a supplementary factor for the climate variation on the AP.
基金sponsored by the National Key Research and Development Program of China(Grant No.2018YFC1501706)the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(Grant No.2019QZKK0105)+2 种基金National Natural Science Foundation of China(Grant No.41975088)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA20100300)the Basic Research Fund of CAMS(Grants No.2021Z007).
文摘The prediction of summer precipitation over the Yangtze River basin(YRB)has long been challenging,especially during June-July(JJ),when the mei-yu generally occurs.This study explores the potential signal for the YRB precipitation in JJ and reveals that the Tibetan Plateau tropospheric temperature(TPTT)in the middle and upper levels during the preceding December-January(DJ)is significantly correlated with JJ YRB precipitation.The close connection between the DJ TPTT anomaly with JJ YRB precipitation may be due to the joint modulation of the DJ ENSO and spring TP soil temperatures.The lagged response to an anomalously cold TPTT during the preceding DJ is a TPTT that is still anomalously cold during the following JJ.The lower TPTT can lead to an anomalous anticyclone to the east of Lake Baikal,an anomalous cyclone at the middle latitudes of East Asia,and an anomalous anticyclone over the western North Pacific.Meanwhile,the East Asian westerly jet shifts southward in response to the meridional thermal gradient caused by the colder troposphere extending from the TP to the east of Lake Baikal.The above-mentioned circulation anomalies constitute the positive anomaly of the East Asia-Pacific pattern,known to be conducive to more precipitation over the YRB.Since the DJ TPTT contains both the land(TP soil temperature)and ocean(ENSO)signals,it has a closer relationship with the JJ precipitation over the YRB than the DJ ENSO alone.Therefore,the preceding DJ TPTT can be considered an alternative predictor of the JJ YRB precipitation.
基金National Key RD Program of China Grant(2018YFB1801504)the President Funding of China Academy of Engineering Physics with No.YZJJLX2018009.
文摘In terahertz communication,the direct frequency conversion structure in which orthogonal mixer is the main frequency conversion unit,makes engineers get into trouble of in-phase(I)branch and quadrature(Q)branch imbalance,carrier wave leakage,etc.These damages result in system performance tremendous degrades.We proposed a semiblind method to estimate the I/Q imbalance of THz orthogonal modulator,based on predefined preamble and pilot symbols for quadrature amplitude modulation(QAM).In this paper,a transmitter with Y band quadrature mixer and 20Gbps base-band signal has been tested.The bandwidth of the baseband signal was 7GHz,and the modulation type was 16QAM.By this method,7dB improvement of the system’s symbol Mean Square Error(MSE)has been got.That means the proposed method can be used to eliminate the I/Q imbalance effectively.
基金Project supported by the National Postdoctoral Program for Innovative Talents,China(Grant No.BX201700184)the National Key Research and Development Program of China(Grant Nos.2016YFB0400105 and 2017YFB0403102)
文摘Pulsed metal organic chemical vapor deposition was employed to grow nearly polarization matched InAlGaN/GaN heterostructures.A relatively low sheet carrier density of 1.8×10^(12)cm^(-2),together with a high electron mobility of 1229.5 cm^2/V·s,was obtained for the prepared heterostructures.The surface morphology of the heterostructures was also significantly improved,i.e.,with a root mean square roughness of 0.29 nm in a 2μm×2μm scan area.In addition to the improved properties,the enhancement-mode metal–oxide–semiconductor high electron mobility transistors(MOSHEMTs)processed on the heterostructures not only exhibited a high threshold voltage(VTH)of 3.1 V,but also demonstrated a significantly enhanced drain output current density of 669 m A/mm.These values probably represent the largest values obtained from the InAlGaN based enhancement-mode devices to the best of our knowledge.This study strongly indicates that the InAlGaN/GaN heterostructures grown by pulsed metal organic chemical vapor deposition could be promising for the applications of novel nitride-based electronic devices.
基金supported by the Open Fund of Engineering laboratory of Spatial Information Technology of Highway Geological Disaster Early Warning in Hunan Province(Changsha University of Science & Technology, Grant No:KFJ150602)Hunan Province Science and Technology Program Funded Projects, China (Grant No:2015NK3035)
文摘A functional model named EIO(Errors-In-Observations) is proposed for general TLS(total least-squares)adjustment. The EIO model only considers the correction of the observation vector, but doesn't consider to correct all elements in the design matrix as the EIV(Errors-In-Variables) model does, furthermore, the dimension of cofactor matrix is much smaller. Iterative algorithms for the parameter estimation and their precise covariance matrix are derived rigorously, and the computation steps are also presented. The proposed approach considers the correction of the observations in the coefficient matrix, and ensures their agreements in every matrix elements. Parameters and corrections can be solved at the same time.An approximate solution and a precise solution of the covariance matrix can be achieved by corresponding algorithms. Applications of EIO model and the proposed algorithms are demonstrated with several examples. The results and comparative studies show that the proposed EIO model and algorithms are feasible and reliable for general adjustment problems.
基金financially supported by the Natural Science Foundation of Sichuan Province(2023NSFSC0915)the Postdoctoral Research Project Special Fund of Sichuan Province and Natural Science Starting Project of SWPU(2023QHZ017).
文摘The investigation concentrates on friction stir welded(FSW)Al-Cu-Li alloy concerning its local microstructural evolution and mechanical properties.The grain features were characterized by electron back scattered diffraction(EBSD)technology,while precipitate characterization was conducted by using transmission electron microscopy(TEM)aligned along[011]Al and[001]Al zone axes.The mechanical properties are evaluated through micro-hardness and tensile testing.It can be found that nugget zones exhibit finely equiaxed grains evolved through complete dynamic recrystallization(DRX),primarily occurring in continuous dynamic recrystallization(CDRX)and discontinuous dynamic recrystallization(DDRX).In the thermal-mechanically affected zone(TMAZ),numerous sub-structured grains,exhibiting an elongated morphology,were created due to partial DRX,signifying the dominance of CDRX,DDRX,and geometric dynamic recrystallization(GDRX)in this region.T_(1)completely dissolves in the nugget zone(NZ)leading to the formation of Guinier-Preston zones and increase ofδ′,β′and S′.Conversely,T_(1)partially solubilizes in TMAZ,the lowest hardness zone(LHZ)and heat affected zone(HAZ),and the residual T_(1)undergoes marked coarsening,revealing various T_(1)variants.The solubilization and coarsening of T_(1)are primary contributors to the degradation of hardness and strength.θ′primarily dissolves and coarsens in NZ and TMAZ,whilst this precipitate largely coarsens in HAZ and LHZ.σ,TB,grain boundary phases(GBPs)and precipitate-free zone(PFZ)are newly generated during FSW.σexists in the TMAZ,LHZ and HAZ,whereas TB nucleates in NZ.GBPs and PFZ mostly develop in LHZ and HAZ,which can cause strain localization during tensile deformation,potentially leading to LHZ joint fracture.
基金supported by the National Natural Science Foundation of China under Grant No.61301051
文摘This paper presents the design and simulation of several fixed-tuned sub-harmonic mixers cover frequencies from 110 GH to 130 GHz, 215 GH to 235 GHz, 310 GH to 350 GHz, and 400 GH to 440 GHz. Among them, 120 GHz, 225 GHz, 330 GHz subharmonic mixers are designed with flip-chipped planar schottky diode mounted onto a suspended quartz-based substrate, the 225 GHz and 425 GHz subharmonic mixers are GaAs membrane integrated, and the 115 GHz subharmonic mixer has been fabricated and tested already.
