Hemiparesis is one of the most common consequences of stroke. Advanced rehabilitation techniques are essential for restoring motor function in hemiplegic patients. Functional electrical stimulation applied to the affe...Hemiparesis is one of the most common consequences of stroke. Advanced rehabilitation techniques are essential for restoring motor function in hemiplegic patients. Functional electrical stimulation applied to the affected limb based on myoelectric signal from the unaffected limb is a promising therapy for hemiplegia. In this study, we developed a prototype system for evaluating this novel functional electrical stimulation-control strategy. Based on surface electromyography and a vector machine model, a self-administered, muki-movement, force-modulation functional electrical stimulation-prototype system for hemiplegia was implemented. This paper discusses the hardware design, the algorithm of the system, and key points of the self-oscillation-prone system. The experimental results demonstrate the feasibility of the prototype system for further clinical trials, which is being conducted to evaluate the efficacy of the proposed rehabilitation technique.展开更多
Three dimensional (3D) microscopic distributions of dolomite and calcite in a limestone sample have been analyzed with a data-constrained modeling (DCM) technique using synchrotron radiation-based multi-energy X-ray c...Three dimensional (3D) microscopic distributions of dolomite and calcite in a limestone sample have been analyzed with a data-constrained modeling (DCM) technique using synchrotron radiation-based multi-energy X-ray computed tomography (CT) data as constraints. In order to optimize the experimental parameters, X-ray CT simulations and DCM analysis of a numerical phantom consisting of calcite (CaCO3) and dolomite (CaMg(CO3)2) have been used to investigate the effects on the predicted results in relation to noise, X-ray energy and sample-to-detector distance (SDD). The simulation results indicate that the optimal X-ray energies are 25 and 35 keVs, and the SDD is 10 mm. The high resolution 3D distributions of mineral phases of a natural limestone have been obtained. The results are useful for quantitative understanding of mineral, porosity, and physical property distributions in relation to oil and gas reservoirs hosted in carbonate rocks, which account for more than half of the world’s conventional hydrocarbon resources. The case studied is also instructive for the applicability of the DCM methods for other types of composite materials with modest atomic number contrasts between the mineral phases.展开更多
The Lower Cretaceous Jiufotang Formation in western Liaoning is the most important fossil production horizon of the Jehol Biota, which is widely distributed in the Mesozoic basins of western Liaoning. Due to the influ...The Lower Cretaceous Jiufotang Formation in western Liaoning is the most important fossil production horizon of the Jehol Biota, which is widely distributed in the Mesozoic basins of western Liaoning. Due to the influence of historical data, previous scholars believed that there was no volcanic activity in the Jiufotang Formation in western Liaoning. In a field investigation in western Liaoning, the authors discovered basalt and andesite in the Hujiayingzi bed. In addition, a conformable boundary was found between the Yixian and the Jiufotang formations. It indicates that both the Jiufotang Formation and the Yixian Formation are strata containing volcanic-sedimentary rocks, only differing in strength of volcanic activity.展开更多
Background:Primary health care system is a critical component of diabetes care and management.This article aimed to analyze the availability of glucose-lowering drugs in primary health institutions(PHIs)in China,and t...Background:Primary health care system is a critical component of diabetes care and management.This article aimed to analyze the availability of glucose-lowering drugs in primary health institutions(PHIs)in China,and to explore the relationship between availability of glucose-lowering drugs and medication adherence among type 2 diabetes mellitus(T2DM)patients.Methods:This cross-sectional study conducted in Shandong Province,eastern China(hereafter referred to as Shandong),between August and December 2017.In total,2520 community-managed T2DM patients were selected from 68 PHIs in Shandong,including 62 village-level and 6 township-level PHIs.The self-developed questionnaire was used to survey the availability of glucose-lowering drugs in PHIs.Patients’medication adherence was assessed by four self-reported questions,and was classified as either adherent or non-adherent.Descriptive statistics was used to analyze the availability of glucose-lowering drugs in PHIs and the medication adherence among the T2DM patients.Multilevel logistic regression models were used to explore the relationship between the availability of glucose-lowering drugs in PHIs and patients’medication adherence.Results:A total of 1866 T2DM patients prescribed with at least one glucose-lowering drug were included in analysis.Among them,58.5%patients followed their antidiabetic treatment well.In village-level PHIs,the patient’s adherence rate was lower than in township-level PHIs(55.9%vs.61.1%,P<0.05).Among the 68 PHIs,average(2.53±0.97)glucose-lowering products(generic names)were available,which in village-level PHIs were less than in township-level PHIs(2.47 vs.3.17,P<0.05).And the number of available glucose-lowering products in PHIs was associated with the adherence of T2DM patients.Conclusion:Poor availability of glucose-lowering products was found in PHIs in Shandong.The availability of glucose-lowering products in PHIs was positively associated with patients’medication adherence,and could be enhanced to improve the control of diabetes in primary care settings.展开更多
Sequence tag index in the field of computational proteomics can be used to facilitate faster open-search-based identification of modified peptides and in-depth analysis of mass spectrometry data. In protein-identifica...Sequence tag index in the field of computational proteomics can be used to facilitate faster open-search-based identification of modified peptides and in-depth analysis of mass spectrometry data. In protein-identification search engines, sequence tag index are playing a prominent role in recent ten years due to fast searching speed. However, in pursuit of less index space consumption, some protein search engines design excessively concise index schemes which lead to higher computational burden. We proposed a new tag index scheme named TIIP with a better balance between space and time complexity. TIIP has a unique two-level hierarchical index structure which allows rapid retrieval of all peptide sequences and their corresponding masses. Theoretically, the index space consumption of TIIP is not much higher compared to the typical tag index schemes, but the time complexity of sequence retrieval can be reduced to O(1), and practically, TIIP has about one million fold improvement in searching speed compared with brute force approach.展开更多
Although climate change has convincingly been linked to the evolution of human civilization on different temporal scales,its role in influencing the spatial patterns of ancient civilizations has rarely been investigat...Although climate change has convincingly been linked to the evolution of human civilization on different temporal scales,its role in influencing the spatial patterns of ancient civilizations has rarely been investigated,The northward shift of the ancient Silk Road(SR)route from the Tarim Basin(TB)to the Junggar Basin during~420-850 CE provides the opportunity to investigate the relationship between climate change and the spatial evolution of human societies.Here,we use a new high-resolution chironomidbased temperature reconstruction from arid China,combined with hydroclimatic and historical datasets,to assess the possible effects of climate fluctuations on the shift of the ancient SR route,We found that a cooling/drying climate in the TB triggered the SR route shift during~420-600 CE,However,a warming/wetting climate during~600-850 CE did not inhibit this shift,but instead promoted it,because of the favorable climate-induced geopolitical conflicts between the Tubo Kingdom and the Tang Dynasty in the TB.Our findings reveal two distinct ways in which climate change drove the spatial evolution of human civilization,and they demonstrate the flexibility of societal responses to climate change.展开更多
Controllable and scalable preparation of electrocatalyst materials holds significant importance for their practical application.Magnetron sputtering is a highly effective synthesis method,known for its producing unifo...Controllable and scalable preparation of electrocatalyst materials holds significant importance for their practical application.Magnetron sputtering is a highly effective synthesis method,known for its producing uniform films and allowing easy control of component compositions.In this paper,we propose an in-situ synthesis method for layered double hydroxide(LDH)electrocatalysts through sacrificing magnetron sputtered films.The resulting FeCo-LDH catalyst demonstrated a low overpotential of only 300 mV at 10 mA·cm^(-2).Furthermore,we conducted spectroscopic analysis to investigate the surface changes of the catalysts during the oxygen evolution reaction(OER)process.Our findings indicated that the formation of Co oxyhydroxides plays a beneficial role in enhancing the catalytical performance of the FeCo-LDH for OER reaction.This restructuring strategy of converting a magnetron-sputtered sacrificial film into a catalytical LDH introduces a new avenue to the synthesis of transition metal-based electrocatalysts.展开更多
Reconstructing temperature changes along the Silk Road(SR)over the last two millennia can provide insights into past global changes and their impact on the rise and fall of ancient civilizations in this region.Numerou...Reconstructing temperature changes along the Silk Road(SR)over the last two millennia can provide insights into past global changes and their impact on the rise and fall of ancient civilizations in this region.Numerous high-quality single-site paleotemperature records have been produced for the eastern part of the SR(mainly for the Xinjiang region and its surrounding areas),which provide the data basis for a comprehensive synthesis.In this study,we used objective criteria to select 10 highquality ones from 30 temperature reconstructions derived from various geological archives including lacustrine sediments,ice cores,and tree rings in this region.Our aims are to summarize the pattern of temperature change over the past 2000 years,to provide a long-term viewpoint on the present warming,and to evaluate the impact of climate change on civilizations along the SR.The principal results are as follows:(1)The temperature variations over the last millennium are mutually consistent within these records.The study area experienced typical climate anomalies during the Medieval Warm Period(MWP,AD 1000-1250),the Little Ice Age(LIA,AD 1450-1850),and the Current Warm Period(CWP,AD 1850 to present);however,contrary to previous knowledge,the amplitude of climatic warming during the CWP did not exceed that during the MWP.(2)Fewer temperature records were available for the interval AD 1–1000,and there were large differences between them.For example,the reconstructed climate during both the Han Dynasty and the Sui-Tang Dynasties was either warm or cold,without prevailing consensus.(3)The warming during the MWP favored the rapid development of the SR route along the northern slopes of the Tianshan Mountains,and the cooling during the LIA contributed to the decline of the SR marked by the closure of the Jiayuguan Pass.Notably,the scarcity of temperature records and the discrepancies between them during AD 1-1000 in the eastern part of the SR have hindered our understanding of the hydroclimatic changes and their influence on the development of civilizations along the SR.Thus,it is important to obtain an increased number of high-quality reliable records spanning the past 2000 year,and to examine the occurrence of local signals of temperature changes during the period of AD 1-1000.On the other hand,the paleotemperature investigation on the western part of the SR over the last two millennia is wholly insufficient,and thus more high-quality single-site and integrated studies are needed,to facilitate more comprehensive insights into the coupled relationship between climate change and the rise and fall of civilizations along the entire length of the Silk Road.展开更多
Lacking timely access to rescue resources is one of the main causes of casualties in tunnel collapse.To provide timely rescue,this study proposed a multi-objective preallocation model of special emergency resources fo...Lacking timely access to rescue resources is one of the main causes of casualties in tunnel collapse.To provide timely rescue,this study proposed a multi-objective preallocation model of special emergency resources for tunnel collapse based on demand time.Efficiency,multiple coverage,and cost-effectiveness are taken as the key objectives of the model;the demand time service range is used as a coverage decision factor considering the unique nature of tunnel collapse.The weight of potential disaster-affected points and other general factors are also considered in this model in order to thoroughly combine the distribution of disaster points and service areas.Further,we take 15 main tunnel projects under construction in China as an example.When the relative proximity to the ideal point of the selected optimal schemeε_(a)is smaller than 0.5,we will adjust the weight of three objectives and reselect the optimal scheme untilε_(a)>0.5.Compared with the not preallocated case,the number of rescue rigs needed is reduced by 8.3%,the number of covered potential disaster-affected points is increased by 36.36%,the weighted coverage times are increased from 0.853 to 1.383,and the weighted distance is significantly reduced by 99%when the rescue rigs are preallocated,verifying the feasibility and superiority of the proposed model.展开更多
Low-melting-point alloys have an extensive applications in the fields of materials processing, phase change energy storage, electronic and electrical automatic control, continuous casting simulation, welding, etc. Spe...Low-melting-point alloys have an extensive applications in the fields of materials processing, phase change energy storage, electronic and electrical automatic control, continuous casting simulation, welding, etc. Specifically, the eutectic compositions make up a large number of low-melting-point alloys that are ex- ploited because of their desirable features like single melting peaks, excellent operational reliability, and casting fluidity. However, the fundamental physicochemical properties from the current available liter- ature on low-melting-point multi-component eutectic alloys (LMP-MCEAs) are rather rare and lowly accurate, including the exact melting temperatures and compositions, constituent phases, microstruc- tures and morphologies, melting enthalpies, specific heats, densities, and so on. This lack of information seriously limits the development and application of low-melting-point multi-component eutectic alloys. In this paper, the low-melting-point multi-component eutectic alloys composed of Bi, Cd, Sn, Pb, and In elements synthesized by high vacuum induction melting and fundamental data were investigated by scan- ning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and density analysis instrument. Most of the LMP-MCEAs with complex eu- tectic morphology structures and XRD diffraction patterns could be explained with the fact that they were three-phase eutectic alloys with mixed growth way. Generally, LMP-MCEAs present an extremely low melting point between 48.3 and 124 ℃ and high density between 8 and 10 g/cm3.展开更多
We perform an in-plane optical spectroscopy measurement on high quality Fe Se single crystals grown by a vapor transport technique. Below the structural transition at Ts 90 K, the reflectivity spectrum clearly shows a...We perform an in-plane optical spectroscopy measurement on high quality Fe Se single crystals grown by a vapor transport technique. Below the structural transition at Ts 90 K, the reflectivity spectrum clearly shows a gradual suppression around 400 cm 1and the conductivity spectrum shows a peak at higher frequency. The energy scale of this gap-like feature is comparable to the width of the band splitting observed by ARPES. The low-frequency conductivity consists of two Drude components and the overall plasma frequency is smaller than that of the Fe As based compounds, suggesting a lower carrier density or stronger correlation effect. The plasma frequency becomes even smaller below Tswhich agrees with the very small Fermi energy estimated by other experiments. Similar to iron pnictides, a clear temperature-induced spectral weight transfer is observed for Fe Se, being indicative of strong correlation effect.展开更多
A high resolution range profile(HRRP) is a summation vector of the sub-echoes of the target scattering points acquired by a wide-band radar.Generally, HRRPs obtained in a noncooperative complex electromagnetic environ...A high resolution range profile(HRRP) is a summation vector of the sub-echoes of the target scattering points acquired by a wide-band radar.Generally, HRRPs obtained in a noncooperative complex electromagnetic environment are contaminated by strong noise.Effective pre-processing of the HRRP data can greatly improve the accuracy of target recognition.In this paper, a denoising and reconstruction method for HRRP is proposed based on a Modified Sparse Auto-Encoder, which is a representative non-linear model.To better reconstruct the HRRP, a sparse constraint is added to the proposed model and the sparse coefficient is calculated based on the intrinsic dimension of HRRP.The denoising of the HRRP is performed by adding random noise to the input HRRP data during the training process and fine-tuning the weight matrix through singular-value decomposition.The results of simulations showed that the proposed method can both reconstruct the signal with fidelity and suppress noise effectively, significantly outperforming other methods, especially in low Signal-to-Noise Ratio conditions.展开更多
Stainless steel(SS)has unsatisfied corrosion resistance in many aggressive environments,particularly under a low p H condition in the bioleaching industry.In this study,through surface analyses and electrochemical mea...Stainless steel(SS)has unsatisfied corrosion resistance in many aggressive environments,particularly under a low p H condition in the bioleaching industry.In this study,through surface analyses and electrochemical measurements,the corrosion resistance of a novel Cu-bearing 316L SS was evaluated in the presence of an acid-producing bacterium,Acidithiobacillus caldus SM-1 that was able to create an extremely acidic corrosive environment.The significantly enhanced anti-microbiologically-inducedcorrosion performance could be explained by the intracellular reactive oxygen species(ROS)and Fenton reaction on the Cu-bearing 316L SS.展开更多
Green reactions not only provide us chemical products without any pollution,but also offer us the viable technology to realize difficult tasks in normal conditions.Photo-,photoelectro-,and electrocatalytic reactions a...Green reactions not only provide us chemical products without any pollution,but also offer us the viable technology to realize difficult tasks in normal conditions.Photo-,photoelectro-,and electrocatalytic reactions are indeed powerful tools to help us to embrace bright future.Especially,some gas-involved reactions are extremely useful to change our life environments from energy systems to liquid fuels and cost-effective products,such as H2 evolution(H2 production),02 evolution/reduction,CO2 reduction,N2 reduction(or N2 fixation) reactions.We can provide fuel cells clean H2 for electric vehicles from H2 evolution reaction(HER),at the same time,we also need highly efficient 02 reduction reaction(ORR) in fuel cells for improving the reaction kinetics.Moreover,we can get the clean oxidant O2 from water through O2 evolution reaction(OER),and carry out some reactions without posing any pollution to reaction systems.Furthermore,we can translate the greenhouse gas CO2 into useful liquid fuels through CO2 reduction reaction(CRR).Last but not the least,we can get ammonia from N2 reduction reaction(NRR),which can decrease energy input compared to the traditional Hubble process.These reactions,such as HER,ORR,OER,CRR and NRR could be realized through solar-,photoelectro-and electro-assisted ways.For them,the catalysts used play crucial roles in determining the efficiency and kinds of products,so we should consider the efficiency of catalysts.However,the cost,synthetic methods of catalysts should also be considered.Nowadays,significant progress has been achieved,however,many challenges still exist,reaction systems,catalysts underlying mechanisms,and so on.As extremely active fields,we should pay attention to them.Under the background,it has motivated us to contribute with a roadmap on ’GasInvolved Photo-and Electro-Catalysis’.展开更多
基金supported by the National Natural Science Foundation of China,No.90307013,90707005a grant from the Science&Technology Pillar Program of Jiangsu Province in China,No.BE2013706
文摘Hemiparesis is one of the most common consequences of stroke. Advanced rehabilitation techniques are essential for restoring motor function in hemiplegic patients. Functional electrical stimulation applied to the affected limb based on myoelectric signal from the unaffected limb is a promising therapy for hemiplegia. In this study, we developed a prototype system for evaluating this novel functional electrical stimulation-control strategy. Based on surface electromyography and a vector machine model, a self-administered, muki-movement, force-modulation functional electrical stimulation-prototype system for hemiplegia was implemented. This paper discusses the hardware design, the algorithm of the system, and key points of the self-oscillation-prone system. The experimental results demonstrate the feasibility of the prototype system for further clinical trials, which is being conducted to evaluate the efficacy of the proposed rehabilitation technique.
文摘Three dimensional (3D) microscopic distributions of dolomite and calcite in a limestone sample have been analyzed with a data-constrained modeling (DCM) technique using synchrotron radiation-based multi-energy X-ray computed tomography (CT) data as constraints. In order to optimize the experimental parameters, X-ray CT simulations and DCM analysis of a numerical phantom consisting of calcite (CaCO3) and dolomite (CaMg(CO3)2) have been used to investigate the effects on the predicted results in relation to noise, X-ray energy and sample-to-detector distance (SDD). The simulation results indicate that the optimal X-ray energies are 25 and 35 keVs, and the SDD is 10 mm. The high resolution 3D distributions of mineral phases of a natural limestone have been obtained. The results are useful for quantitative understanding of mineral, porosity, and physical property distributions in relation to oil and gas reservoirs hosted in carbonate rocks, which account for more than half of the world’s conventional hydrocarbon resources. The case studied is also instructive for the applicability of the DCM methods for other types of composite materials with modest atomic number contrasts between the mineral phases.
文摘The Lower Cretaceous Jiufotang Formation in western Liaoning is the most important fossil production horizon of the Jehol Biota, which is widely distributed in the Mesozoic basins of western Liaoning. Due to the influence of historical data, previous scholars believed that there was no volcanic activity in the Jiufotang Formation in western Liaoning. In a field investigation in western Liaoning, the authors discovered basalt and andesite in the Hujiayingzi bed. In addition, a conformable boundary was found between the Yixian and the Jiufotang formations. It indicates that both the Jiufotang Formation and the Yixian Formation are strata containing volcanic-sedimentary rocks, only differing in strength of volcanic activity.
基金funded by the Key Research and Development Program of Shandong Province(Grant No.2018GSF118184).
文摘Background:Primary health care system is a critical component of diabetes care and management.This article aimed to analyze the availability of glucose-lowering drugs in primary health institutions(PHIs)in China,and to explore the relationship between availability of glucose-lowering drugs and medication adherence among type 2 diabetes mellitus(T2DM)patients.Methods:This cross-sectional study conducted in Shandong Province,eastern China(hereafter referred to as Shandong),between August and December 2017.In total,2520 community-managed T2DM patients were selected from 68 PHIs in Shandong,including 62 village-level and 6 township-level PHIs.The self-developed questionnaire was used to survey the availability of glucose-lowering drugs in PHIs.Patients’medication adherence was assessed by four self-reported questions,and was classified as either adherent or non-adherent.Descriptive statistics was used to analyze the availability of glucose-lowering drugs in PHIs and the medication adherence among the T2DM patients.Multilevel logistic regression models were used to explore the relationship between the availability of glucose-lowering drugs in PHIs and patients’medication adherence.Results:A total of 1866 T2DM patients prescribed with at least one glucose-lowering drug were included in analysis.Among them,58.5%patients followed their antidiabetic treatment well.In village-level PHIs,the patient’s adherence rate was lower than in township-level PHIs(55.9%vs.61.1%,P<0.05).Among the 68 PHIs,average(2.53±0.97)glucose-lowering products(generic names)were available,which in village-level PHIs were less than in township-level PHIs(2.47 vs.3.17,P<0.05).And the number of available glucose-lowering products in PHIs was associated with the adherence of T2DM patients.Conclusion:Poor availability of glucose-lowering products was found in PHIs in Shandong.The availability of glucose-lowering products in PHIs was positively associated with patients’medication adherence,and could be enhanced to improve the control of diabetes in primary care settings.
文摘Sequence tag index in the field of computational proteomics can be used to facilitate faster open-search-based identification of modified peptides and in-depth analysis of mass spectrometry data. In protein-identification search engines, sequence tag index are playing a prominent role in recent ten years due to fast searching speed. However, in pursuit of less index space consumption, some protein search engines design excessively concise index schemes which lead to higher computational burden. We proposed a new tag index scheme named TIIP with a better balance between space and time complexity. TIIP has a unique two-level hierarchical index structure which allows rapid retrieval of all peptide sequences and their corresponding masses. Theoretically, the index space consumption of TIIP is not much higher compared to the typical tag index schemes, but the time complexity of sequence retrieval can be reduced to O(1), and practically, TIIP has about one million fold improvement in searching speed compared with brute force approach.
基金supported by the National Key R&D Program of China(2018YFA0606404)the National Natural Science Foundation of China(42371172,41822102)+1 种基金the State Key Laboratory of Cryospheric Science(SKLCS-ZZ-2023)the Foundation for Excellent Youth Scholars of NIEER,CAS(FEYS2019009).
文摘Although climate change has convincingly been linked to the evolution of human civilization on different temporal scales,its role in influencing the spatial patterns of ancient civilizations has rarely been investigated,The northward shift of the ancient Silk Road(SR)route from the Tarim Basin(TB)to the Junggar Basin during~420-850 CE provides the opportunity to investigate the relationship between climate change and the spatial evolution of human societies.Here,we use a new high-resolution chironomidbased temperature reconstruction from arid China,combined with hydroclimatic and historical datasets,to assess the possible effects of climate fluctuations on the shift of the ancient SR route,We found that a cooling/drying climate in the TB triggered the SR route shift during~420-600 CE,However,a warming/wetting climate during~600-850 CE did not inhibit this shift,but instead promoted it,because of the favorable climate-induced geopolitical conflicts between the Tubo Kingdom and the Tang Dynasty in the TB.Our findings reveal two distinct ways in which climate change drove the spatial evolution of human civilization,and they demonstrate the flexibility of societal responses to climate change.
基金support from the National Natural Science Foundation of China(Nos.52250710159,51731008,51671163)。
文摘Controllable and scalable preparation of electrocatalyst materials holds significant importance for their practical application.Magnetron sputtering is a highly effective synthesis method,known for its producing uniform films and allowing easy control of component compositions.In this paper,we propose an in-situ synthesis method for layered double hydroxide(LDH)electrocatalysts through sacrificing magnetron sputtered films.The resulting FeCo-LDH catalyst demonstrated a low overpotential of only 300 mV at 10 mA·cm^(-2).Furthermore,we conducted spectroscopic analysis to investigate the surface changes of the catalysts during the oxygen evolution reaction(OER)process.Our findings indicated that the formation of Co oxyhydroxides plays a beneficial role in enhancing the catalytical performance of the FeCo-LDH for OER reaction.This restructuring strategy of converting a magnetron-sputtered sacrificial film into a catalytical LDH introduces a new avenue to the synthesis of transition metal-based electrocatalysts.
基金supported by the National Natural Science Foundation of China(Grant Nos.41901106,41822102)the National Key R&D Program of China(Grant No.2018YFA0606401)。
文摘Reconstructing temperature changes along the Silk Road(SR)over the last two millennia can provide insights into past global changes and their impact on the rise and fall of ancient civilizations in this region.Numerous high-quality single-site paleotemperature records have been produced for the eastern part of the SR(mainly for the Xinjiang region and its surrounding areas),which provide the data basis for a comprehensive synthesis.In this study,we used objective criteria to select 10 highquality ones from 30 temperature reconstructions derived from various geological archives including lacustrine sediments,ice cores,and tree rings in this region.Our aims are to summarize the pattern of temperature change over the past 2000 years,to provide a long-term viewpoint on the present warming,and to evaluate the impact of climate change on civilizations along the SR.The principal results are as follows:(1)The temperature variations over the last millennium are mutually consistent within these records.The study area experienced typical climate anomalies during the Medieval Warm Period(MWP,AD 1000-1250),the Little Ice Age(LIA,AD 1450-1850),and the Current Warm Period(CWP,AD 1850 to present);however,contrary to previous knowledge,the amplitude of climatic warming during the CWP did not exceed that during the MWP.(2)Fewer temperature records were available for the interval AD 1–1000,and there were large differences between them.For example,the reconstructed climate during both the Han Dynasty and the Sui-Tang Dynasties was either warm or cold,without prevailing consensus.(3)The warming during the MWP favored the rapid development of the SR route along the northern slopes of the Tianshan Mountains,and the cooling during the LIA contributed to the decline of the SR marked by the closure of the Jiayuguan Pass.Notably,the scarcity of temperature records and the discrepancies between them during AD 1-1000 in the eastern part of the SR have hindered our understanding of the hydroclimatic changes and their influence on the development of civilizations along the SR.Thus,it is important to obtain an increased number of high-quality reliable records spanning the past 2000 year,and to examine the occurrence of local signals of temperature changes during the period of AD 1-1000.On the other hand,the paleotemperature investigation on the western part of the SR over the last two millennia is wholly insufficient,and thus more high-quality single-site and integrated studies are needed,to facilitate more comprehensive insights into the coupled relationship between climate change and the rise and fall of civilizations along the entire length of the Silk Road.
基金supported by the funding provided by the National Natural Science Foundation of China(Grant no.51908187)。
文摘Lacking timely access to rescue resources is one of the main causes of casualties in tunnel collapse.To provide timely rescue,this study proposed a multi-objective preallocation model of special emergency resources for tunnel collapse based on demand time.Efficiency,multiple coverage,and cost-effectiveness are taken as the key objectives of the model;the demand time service range is used as a coverage decision factor considering the unique nature of tunnel collapse.The weight of potential disaster-affected points and other general factors are also considered in this model in order to thoroughly combine the distribution of disaster points and service areas.Further,we take 15 main tunnel projects under construction in China as an example.When the relative proximity to the ideal point of the selected optimal schemeε_(a)is smaller than 0.5,we will adjust the weight of three objectives and reselect the optimal scheme untilε_(a)>0.5.Compared with the not preallocated case,the number of rescue rigs needed is reduced by 8.3%,the number of covered potential disaster-affected points is increased by 36.36%,the weighted coverage times are increased from 0.853 to 1.383,and the weighted distance is significantly reduced by 99%when the rescue rigs are preallocated,verifying the feasibility and superiority of the proposed model.
基金supported by the National Natural Science Foundation of China (Nos. 51525401 and 51471044)the Fundamental Research Funds for the Central Universities (No. DUT14LH013)+1 种基金Key Laboratory of Basic Research Projects of Liaoning Province Department of Education (No. LZ2014007)the Natural Science Foundation of Liaoning Province (No. 2014028013)
文摘Low-melting-point alloys have an extensive applications in the fields of materials processing, phase change energy storage, electronic and electrical automatic control, continuous casting simulation, welding, etc. Specifically, the eutectic compositions make up a large number of low-melting-point alloys that are ex- ploited because of their desirable features like single melting peaks, excellent operational reliability, and casting fluidity. However, the fundamental physicochemical properties from the current available liter- ature on low-melting-point multi-component eutectic alloys (LMP-MCEAs) are rather rare and lowly accurate, including the exact melting temperatures and compositions, constituent phases, microstruc- tures and morphologies, melting enthalpies, specific heats, densities, and so on. This lack of information seriously limits the development and application of low-melting-point multi-component eutectic alloys. In this paper, the low-melting-point multi-component eutectic alloys composed of Bi, Cd, Sn, Pb, and In elements synthesized by high vacuum induction melting and fundamental data were investigated by scan- ning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and density analysis instrument. Most of the LMP-MCEAs with complex eu- tectic morphology structures and XRD diffraction patterns could be explained with the fact that they were three-phase eutectic alloys with mixed growth way. Generally, LMP-MCEAs present an extremely low melting point between 48.3 and 124 ℃ and high density between 8 and 10 g/cm3.
基金supported by the National Natural Science Foundation of China(11120101003,11327806)the National Basic Research Program of China(2012CB821403)
文摘We perform an in-plane optical spectroscopy measurement on high quality Fe Se single crystals grown by a vapor transport technique. Below the structural transition at Ts 90 K, the reflectivity spectrum clearly shows a gradual suppression around 400 cm 1and the conductivity spectrum shows a peak at higher frequency. The energy scale of this gap-like feature is comparable to the width of the band splitting observed by ARPES. The low-frequency conductivity consists of two Drude components and the overall plasma frequency is smaller than that of the Fe As based compounds, suggesting a lower carrier density or stronger correlation effect. The plasma frequency becomes even smaller below Tswhich agrees with the very small Fermi energy estimated by other experiments. Similar to iron pnictides, a clear temperature-induced spectral weight transfer is observed for Fe Se, being indicative of strong correlation effect.
基金co-supported by the National Natural Science Foundation of China(Nos.61671463,61471379,61790551 and 61102166)。
文摘A high resolution range profile(HRRP) is a summation vector of the sub-echoes of the target scattering points acquired by a wide-band radar.Generally, HRRPs obtained in a noncooperative complex electromagnetic environment are contaminated by strong noise.Effective pre-processing of the HRRP data can greatly improve the accuracy of target recognition.In this paper, a denoising and reconstruction method for HRRP is proposed based on a Modified Sparse Auto-Encoder, which is a representative non-linear model.To better reconstruct the HRRP, a sparse constraint is added to the proposed model and the sparse coefficient is calculated based on the intrinsic dimension of HRRP.The denoising of the HRRP is performed by adding random noise to the input HRRP data during the training process and fine-tuning the weight matrix through singular-value decomposition.The results of simulations showed that the proposed method can both reconstruct the signal with fidelity and suppress noise effectively, significantly outperforming other methods, especially in low Signal-to-Noise Ratio conditions.
基金financially supported by the National Natural Science Foundation of China(Nos.51871050 and U1660118)the Fundamental Research Funds for the Central Universities(Nos.N180205021,N180203019,and N2002019)the Liaoning Revitalization Talents Program(No.XLYC1907158)。
文摘Stainless steel(SS)has unsatisfied corrosion resistance in many aggressive environments,particularly under a low p H condition in the bioleaching industry.In this study,through surface analyses and electrochemical measurements,the corrosion resistance of a novel Cu-bearing 316L SS was evaluated in the presence of an acid-producing bacterium,Acidithiobacillus caldus SM-1 that was able to create an extremely acidic corrosive environment.The significantly enhanced anti-microbiologically-inducedcorrosion performance could be explained by the intracellular reactive oxygen species(ROS)and Fenton reaction on the Cu-bearing 316L SS.
基金The financial support from the National Natural Science Foundation of China (Nos. 51772312, 21671197)
文摘Green reactions not only provide us chemical products without any pollution,but also offer us the viable technology to realize difficult tasks in normal conditions.Photo-,photoelectro-,and electrocatalytic reactions are indeed powerful tools to help us to embrace bright future.Especially,some gas-involved reactions are extremely useful to change our life environments from energy systems to liquid fuels and cost-effective products,such as H2 evolution(H2 production),02 evolution/reduction,CO2 reduction,N2 reduction(or N2 fixation) reactions.We can provide fuel cells clean H2 for electric vehicles from H2 evolution reaction(HER),at the same time,we also need highly efficient 02 reduction reaction(ORR) in fuel cells for improving the reaction kinetics.Moreover,we can get the clean oxidant O2 from water through O2 evolution reaction(OER),and carry out some reactions without posing any pollution to reaction systems.Furthermore,we can translate the greenhouse gas CO2 into useful liquid fuels through CO2 reduction reaction(CRR).Last but not the least,we can get ammonia from N2 reduction reaction(NRR),which can decrease energy input compared to the traditional Hubble process.These reactions,such as HER,ORR,OER,CRR and NRR could be realized through solar-,photoelectro-and electro-assisted ways.For them,the catalysts used play crucial roles in determining the efficiency and kinds of products,so we should consider the efficiency of catalysts.However,the cost,synthetic methods of catalysts should also be considered.Nowadays,significant progress has been achieved,however,many challenges still exist,reaction systems,catalysts underlying mechanisms,and so on.As extremely active fields,we should pay attention to them.Under the background,it has motivated us to contribute with a roadmap on ’GasInvolved Photo-and Electro-Catalysis’.