Postoperative tumor recurrence remains a predominant cause of treatment failure. In this study, we developed an in situ injectable hydrogel, termed MPB-NO@DOX + ATRA gel, which was locally formed within the tumor rese...Postoperative tumor recurrence remains a predominant cause of treatment failure. In this study, we developed an in situ injectable hydrogel, termed MPB-NO@DOX + ATRA gel, which was locally formed within the tumor resection cavity. The MPB-NO@DOX + ATRA gel was fabricated by mixing a thrombin solution, a fibrinogen solution containing all-trans retinoic acid (ATRA), and a Mn/NO-based immune nano-activator termed MPB-NO@DOX. ATRA promoted the differentiation of cancer stem cells, inhibited cancer cell migration, and affected the polarization of tumor-associated macrophages. The outer MnO2 shell disintegrated due to its reaction with glutathione and hydrogen peroxide in the cytoplasm to release Mn2+ and produce O2, resulting in the release of doxorubicin (DOX). The released DOX entered the nucleus and destroyed DNA, and the fragmented DNA cooperated with Mn2+ to activate the cGAS-STING pathway and stimulate an anti-tumor immune response. In addition, when MPB-NO@DOX was exposed to 808 nm laser irradiation, the Fe-NO bond was broken to release NO, which downregulated the expression of PD-L1 on the surface of tumor cells and reversed the immunosuppressive tumor microenvironment. In conclusion, the MPB-NO@DOX + ATRA gel exhibited excellent anti-tumor efficacy. The results of this study demonstrated the great potential of in situ injectable hydrogels in preventing postoperative tumor recurrence.展开更多
Fifty-three larch interspecific hybrid clones（Larix kaempferi × L.gmelini） and their parent clones were used for growth curve analysis of height variations.The growth curves of the 55 clones were ＇S＇-shaped a...Fifty-three larch interspecific hybrid clones（Larix kaempferi × L.gmelini） and their parent clones were used for growth curve analysis of height variations.The growth curves of the 55 clones were ＇S＇-shaped and 36 exhibited similar curves as the male parent.The coefficients of the logistic models were higher than 0.943,indicating that our results were effective in the simulation of the growth curves.ANOVA analysis showed significant differences in height of different clones （P／0.01）.Average date of maximum height growth was Day 173,and average duration of rapid growth lasted for 50 days.Annual average increase in height was 9.7cm d^（-1） and daily average increase was 0.2 cm.The ratio of GR to the total annual increase in height ranged from 51.2 to 68.8%,with the average being 59.8%.There was a positive correlation between k values and plant heights which benefited from the evaluation of early plant height.There was also a positive correlation between GR（growth stage）,GD（plant height） and annual increase in height.These results are informative to the evaluation of the elite clone selection and provide a theoretical basis for breeding and management.展开更多
In order to avoid the UHVAC (Ultra High Voltage Alternating Current) transmission line with shunt reactor fault voltage smaller problems, through the analysis of single-phase permanent fault when tripping phase termin...In order to avoid the UHVAC (Ultra High Voltage Alternating Current) transmission line with shunt reactor fault voltage smaller problems, through the analysis of single-phase permanent fault when tripping phase terminal voltage characteristics, this paper presents a fault phase voltage signal of the two order derivative and the original signal ratio of a new method for steady-state frequency discrimination single-phase permanent fault. The principle of this method is simple, and it can avoid the problem that the fault voltage caused by the installation of shunt reactor is small. The adaptability and correctness of the proposed method are verified by a large number of simulations.展开更多
The performance of an integrated thermal management system signi?cantly in?uences the stability of special-purpose vehicles;thus,enhancing the heat transfer of the radiator is of great signi?cance.Common research meth...The performance of an integrated thermal management system signi?cantly in?uences the stability of special-purpose vehicles;thus,enhancing the heat transfer of the radiator is of great signi?cance.Common research methods for radiators include?uid mechanics numerical simulations and experimental measurements,both of which are time-consuming and expensive.Applying the surrogate model to the analysis of the?ow and heat transfer in louvered?ns can effectively reduce the computational cost and obtain more data.A simpli?ed louvered-?n heat transfer unit was established,and computational?uid dynamics(CFD)simulations were conducted to obtain the?ow and heat transfer characteristics of the geometric structure.A three-factor and six-level orthogonal design was established with three structural parameters:angleθ,length a,and pitch L_p of the louvered?ns.The results of the orthogonal design were subjected to a range analysis,and the effects of the three parametersθ,a,and L_p on the j,f,and JF factors were obtained.Accordingly,a proxy model of the heat transfer performance for louvered?ns was established based onthe arti?cial neural network algorithm,and the model was trained with the data obtained by the orthogonal design.Finally,the?n structure with the largest JF factor was realized.Compared with the original model,the optimizedmodel improved the heat transfer factor j by 2.87%,decreased the friction factor f by 30.4%,and increased the comprehensive factor JF by 15.7%.展开更多
In the neutral hydrogen(H I)galaxy survey,a significant challenge is to identify and extract the H I galaxy signal from the observational data contaminated by radio frequency interference(RFI).For a drift-scan survey,...In the neutral hydrogen(H I)galaxy survey,a significant challenge is to identify and extract the H I galaxy signal from the observational data contaminated by radio frequency interference(RFI).For a drift-scan survey,or more generally a survey of a spatially continuous region,in the time-ordered spectral data,the H I galaxies and RFI all appear as regions that extend an area in the time-frequency waterfall plot,so the extraction of the H I galaxies and RFI from such data can be regarded as an image segmentation problem,and machine-learning methods can be applied to solve such problems.In this study,we develop a method to effectively detect and extract signals of H I galaxies based on a Mask R-CNN network combined with the PointRend method.By simulating FAST-observed galaxy signals and potential RFI impact,we created a realistic data set for the training and testing of our neural network.We compared five different architectures and selected the best-performing one.This architecture successfully performs instance segmentation of H I galaxy signals in the RFI-contaminated time-ordered data,achieving a precision of 98.64%and a recall of 93.59%.展开更多
Many effective optimization algorithms require partial derivatives of objective functions, while some optimization problems' objective functions have no derivatives. According to former research studies, some sear...Many effective optimization algorithms require partial derivatives of objective functions, while some optimization problems' objective functions have no derivatives. According to former research studies, some search directions are obtained using the quadratic hypothesis of objective functions. Based on derivatives, quadratic function assumptions, and directional derivatives, the computational formulas of numerical first-order partial derivatives, second-order partial derivatives, and numerical second-order mixed partial derivatives were constructed. Based on the coordinate transformation relation, a set of orthogonal vectors in the fixed coordinate system was established according to the optimization direction. A numerical algorithm was proposed, taking the second order approximation direction as an example. A large stepsize numerical algorithm based on coordinate transformation was proposed. Several algorithms were validated by an unconstrained optimization of the two-dimensional Rosenbrock objective function. The numerical second order approximation direction with the numerical mixed partial derivatives showed good results. Its calculated amount is 0.2843% of that of without second-order mixed partial derivative. In the process of rotating the local coordinate system 360°, because the objective function is more complex than the quadratic function, if the numerical direction derivative is used instead of the analytic partial derivative, the optimization direction varies with a range of 103.05°. Because theoretical error is in the numerical negative gradient direction, the calculation with the coordinate transformation is 94.71% less than the calculation without coordinate transformation. If there is no theoretical error in the numerical negative gradient direction or in the large-stepsize numerical optimization algorithm based on the coordinate transformation, the sawtooth phenomenon occurs. When each numerical mixed partial derivative takes more than one point, the optimization results cannot be improved. The numerical direction based on the quadratic hypothesis only requires the objective function to be obtained, but does not require derivability and does not take into account truncation error and rounding error. Thus, the application scopes of many optimization methods are extended.展开更多
Polycyclic aromatic hydrocarbons(PAHs)are a typical class of persistent organic pollutants that is ubiquitous worldwide.Previous animal studies suggested that PAHs had adverse effects on female reproduction.However,th...Polycyclic aromatic hydrocarbons(PAHs)are a typical class of persistent organic pollutants that is ubiquitous worldwide.Previous animal studies suggested that PAHs had adverse effects on female reproduction.However,the human data regarding relationship of PAHs exposure with women reproductive health,such as ovarian dysfunction,are scarce.In this case-control study,the associations of serum levels of PAHs with the risk of premature ovarian failure(POF)and reproductive hormones in Chinese women were investigated,with recruiting 157 POF patients and 217 healthy women.The serum levels of 12 types of PAHs,as well as reproductive hormones,including follicle-stimulating hormone,luteinizing hormone and anti-mullerian hormone,were determined.In the logistic regression models,most individual PAH congeners showed significantly positive correlations with the risk of POF(p<0.05),except for fluorine and pyrene.Benzo(a)pyrene(BaP),as the most carcinogenic PAH congener,was observed to be significantly positively associated with the risk of POF.After adjustment for age,body mass index,educational levels and household income,per one-unit increase in the log-transformed BaP concentration was significantly correlated with 2.191-fold increased risk of POF(OR=2.191,95%CI:1.634-2.938,p<0.05).To the best of our knowledge,this is the first study to report an association between internal exposure levels of PAHs and the increased risk of POF in women.展开更多
The current study evaluated the effects of oxalic acid(OA)application on the growth and Mn phytoremediation efficiency of Polygonum pubescens Blume cultivated in three different manganese(Mn)-contaminated soils sample...The current study evaluated the effects of oxalic acid(OA)application on the growth and Mn phytoremediation efficiency of Polygonum pubescens Blume cultivated in three different manganese(Mn)-contaminated soils sampled from an unexplored area(US),an explored area(ES)and a tailing area(TS)of the Ertang Mn mine,South China.The supplied levels of OA were 0(control),1(low level),3(medium level),and 9(high level)mmol/kg,referred to as CK,OA1,OA3 and OA9,respectively.The results revealed that the average water-extractable Mn concentrations US,ES and TS amended with OA increased by 214.13,363.77 and 266.85%,respectively.All OA supply levels increased plant growth and Mn concentrations in US.The low OA supply level increased plant growth in ES and TS;however,contrasting results were found for the medium and high OA supply levels.Plant Mn concentrations and total Mn increased in ES and TS in response to all OA supply levels.Total Mn in the aerial parts increased by 81.18,44.17 and 83.17%in US,ES and TS,respectively;the corresponding percentages for the whole plants were 81.53,108.98 and 77.91%,respectively.The rate of·O_(2)^(−)production and malondialdehyde(MDA)concentrations increased in response to OA amendment,especially the medium and high OA supply levels in ES and TS.In general,antioxidant enzymes might play a vital role in alleviating Mn stress in plants cultivated in US,while non-enzymatic antioxidants might be the main factor for plants cultivated in ES and TS.展开更多
The probabilistic control volume method has great prospects in correlating the effects of specimen size,notch and loading type on fatigue life or fatigue strength.In this work,the effects of notch size and loading typ...The probabilistic control volume method has great prospects in correlating the effects of specimen size,notch and loading type on fatigue life or fatigue strength.In this work,the effects of notch size and loading type on fatigue life are investigated by using the probabilistic control volume method.Rotating bending and axial loading fatigue te«t«are at first performed on the hourglass specimen,circumferential V-notch specimen and V-notch plate specimen of 30CrMnSiA steel.Experimental results indicate that the notch reduces the fatigue strength of specimens in terms of nominal stress amplitude while in terms of local stress amplitude,the notch specimen could endure higher fatigue strength.Then,the probabilistic control volume method is used to evaluate the effects of notch size and loading type on fatigue life.It is shown that the probabilistic control volume method correlates well the effects of notch size and loading type on fatigue life,even for the local stress of the notch root exceeding the yield stress of the material.展开更多
In total,9,552 documents were extracted from the Web of Science Core Collection and subjected to knowledge mapping and visualization analysis for the field of phytoremediation of HM-contaminated soil(PHMCS)with CiteSp...In total,9,552 documents were extracted from the Web of Science Core Collection and subjected to knowledge mapping and visualization analysis for the field of phytoremediation of HM-contaminated soil(PHMCS)with CiteSpace 5.7 R3 software.The results showed that(1)the number of publications increased linearly over the studied period.The top 10 countries/regions,institutions and authors contributing to this field were exhibited.(2)Keyword co-occurrence cluster analysis revealed a total of 8 clusters,including“Bioremediation,”“Arsenic,”“Biochar,”“Oxidative stress,”“Hyperaccumulation,”“EDTA,”“Arbuscular mycorrhizal fungi,”and“Environmental pollution”clusters(3)In total,334 keyword bursts were obtained,and the 25 strongest,longest duration,and newest keyboard bursts were analyzed in depth.The strongest keyword burst test showed that the hottest keywords could be divided into 7 groups,i.e.,“Plant bioremediation materials,”“HM types,”“Chelating amendments,”“Other improved strategies,”“Bioremediation characteristics,”“Risk assessment,”and“Other.”Almost half of the newest topics had emerged in the past 3 years,including“biochar,”“drought,”“health risk assessment,”“electrokinetic remediation,”“nanoparticle,”and“intercropping.”(4)In total,9 knowledge base clusters were obtained in this study.The studies of Ali et al.(2013),Blaylock et al.(1997),Huang et al.(1997),van der Ent et al.(2013),Salt et al.(1995),and Salt(1998),which had both high frequencies and the strongest burst scores,have had the most profound effects on PHMCS research.Finally,future research directions were proposed.展开更多
Nutrient status and pollution levels are the main factors affecting soil restoration.The nutrient status and pollution levels in five areas,an unexplored mine area(UA),an explored mine area(EA),a tailings area(TA),a r...Nutrient status and pollution levels are the main factors affecting soil restoration.The nutrient status and pollution levels in five areas,an unexplored mine area(UA),an explored mine area(EA),a tailings area(TA),a reclamation area(RA)and an agricultural area(AA),around the Pingle manganese mine in Guangxi,China,were assessed in this study.The results showed that the average total phosphorus in these five areas ranged from 1.05 to 1.57 mg/kg,corresponding to grades of extremely high and high.The average total nitrogen values were 0.19,0.69,0.93,1.24 and 1.67 mg/kg in EA,TA,RA,UA and AA,corresponding to grades of very low,low,medium-low,medium-high and medium-high,respectively.The average organic matter values were 12.78,8.92,22.77,21.29 and 29.11 mg/kg in EA,TA,RA,UA and AA,which corresponded to grades of medium-low,low,medium-high,medium-high and medium-high,respectively.All these results indicated that the total phosphorus was sufficient in these areas,while the total nitrogen and organic matter were insufficient in EA,TA and RA.The available concentrations of Mn and Zn corresponded to the intermediate grade,while the values for Cu corresponded to the very low grade;these might be another factor restricting ecological reclamation.Contamination and ecological risk assessments based on the single contamination index,Nemerow multi-factor index and potential ecological risk index showed that the five tested areas around the Mn mine were considered heavily polluted and presented high ecological risk.Mn and Cd were the dominant pollutants.展开更多
Atmospheric fine particles （PM2.5） were collected in this study with middle volume samplers in Fuzhou, China, during both normal days and haze days in summer （September 2007） and winter （january 2008）. The conce...Atmospheric fine particles （PM2.5） were collected in this study with middle volume samplers in Fuzhou, China, during both normal days and haze days in summer （September 2007） and winter （january 2008）. The concentrations, distributions, and sources of polycyclic aromatic hydrocarbons （PAHs）, organic carbon （OC）, elemental carbon （EC）, and water soluble inorganic ions （WSIls） were determinated. The results showed that the concentrations of PM2.s, PAHs, OC, EC, and WSIIs were in the orders of haze 〉 normal and winter〉 summer. The dominant PAHs of PM2.s in Fuzhou were Fluo, Pyr, Chr, BbF, BkF, BaP, BghiP, and IcdP, which represented about 80.0% of the total PAHs during different sampling periods. The BaPeq concentrations of ^-~PAHs were 0.78, 0.99, 1.22, and 2.43 ng/m3 in summer normal, summer haze, winter normal, and winter haze, respectively. Secondary pollutants （SO42 , NO3 , NH4＊, and OC） were the major chemical compositions of PM2.5, accounting for 69.0%, 55.1%, 63.4%, and 64.9% of PM2.s mass in summer normal, summer haze, winter normal, and winter haze, respectively. Correspondingly, secondary organic carbon （SOC） in Fuzhou accounted for 20.1%, 48.6%, 24.5%, and 50.5% of OC. The average values of nitrogen oxidation ratio （NOR） and sulfur oxidation ratio （SOR） were higher in haze days （0.08 and 0.27） than in normal days （0.05 and 0.22）. Higher OC/EC ratios were also found in haze days （5.0） than in normal days （3.3）. Correlation analysis demonstrated that visibility had positive correlations with wind speed, and neg- ative correlations with relative humidity and major air pollutants. Overall, the enrichments of PM2.5, OC, EC, SO42 ,andNO3 promoted haze formation. Furthermore, the diagnostic ratios of IcdP/（IcdP ＋ BghiP）, lcdP/BghiP, OC/EC, and NO3 /SO42 indicated that vehicle exhaust and coal consumption were the main sources of pollutants in Fuzhou.展开更多
In the present investigation a wrought magnesium alloy AZ31 was successfully processed by the accumulative roll-bonding （ARB） at gradient temperature up to six cycles with the lowest temperature of 250 °C. This...In the present investigation a wrought magnesium alloy AZ31 was successfully processed by the accumulative roll-bonding （ARB） at gradient temperature up to six cycles with the lowest temperature of 250 °C. This is performed through different thermomechanical processing routes （different ARB cycles at different temperatures of 350-200 °C）. The microstructures and mechanical properties were investigated. The results indicate that significant grain refinement is observed after the first two cycles at the highest ARB temperature as a result of dynamic recrystallization, which is necessary for the subsequently ARB cycles at relatively lower temperature with the aim to restrict grain growth. No significant finer grain size was observed through the fifth and sixth cycles while the microstructure homogeneity is further improved. The grain structure can be effectively refined at lower ARB processing temperature and higher cycles. The resulting material exhibited high strength and relatively high ductility at ambient temperature when ARB deformed above 250 °C. The mechanical properties of the ARB deformed materials are strongly dependent on several main factors： the amount and the homogeneity of strain achieved, grain size and microstructure homogeneity, textures developed during ARB and interface bonding quality.展开更多
基金supported by the National Natural Science Foundation of China(No.82003298)the Scientiffc and Technological Project of Henan Province(No.232102310392)+5 种基金the Key Research and Development Projects of Henan Province(No.222102310453,212102311025)Postdoctoral Research Grant in Henan Province(No.201901025)the Key Research Project of Henan Higher Education Institutions(No.18A350003)Open Fund of Key Laboratory of Targeting Therapy and Diagnosis for Critical Diseases,Henan Province(No.NMZL2020102)the Natural Science Foundation of Chongqing(No.cstc2019jcyj-msxmX0035)the Scientiffc Research Seedling Project of Chongqing Medicinal Biotechnology Association(No.cmba2022kyym-zkxmQ0009).
文摘Postoperative tumor recurrence remains a predominant cause of treatment failure. In this study, we developed an in situ injectable hydrogel, termed MPB-NO@DOX + ATRA gel, which was locally formed within the tumor resection cavity. The MPB-NO@DOX + ATRA gel was fabricated by mixing a thrombin solution, a fibrinogen solution containing all-trans retinoic acid (ATRA), and a Mn/NO-based immune nano-activator termed MPB-NO@DOX. ATRA promoted the differentiation of cancer stem cells, inhibited cancer cell migration, and affected the polarization of tumor-associated macrophages. The outer MnO2 shell disintegrated due to its reaction with glutathione and hydrogen peroxide in the cytoplasm to release Mn2+ and produce O2, resulting in the release of doxorubicin (DOX). The released DOX entered the nucleus and destroyed DNA, and the fragmented DNA cooperated with Mn2+ to activate the cGAS-STING pathway and stimulate an anti-tumor immune response. In addition, when MPB-NO@DOX was exposed to 808 nm laser irradiation, the Fe-NO bond was broken to release NO, which downregulated the expression of PD-L1 on the surface of tumor cells and reversed the immunosuppressive tumor microenvironment. In conclusion, the MPB-NO@DOX + ATRA gel exhibited excellent anti-tumor efficacy. The results of this study demonstrated the great potential of in situ injectable hydrogels in preventing postoperative tumor recurrence.
基金supported by Grants from the National Science and Technology Pillar Program of China(No.2015DAD09B01)
文摘Fifty-three larch interspecific hybrid clones（Larix kaempferi × L.gmelini） and their parent clones were used for growth curve analysis of height variations.The growth curves of the 55 clones were ＇S＇-shaped and 36 exhibited similar curves as the male parent.The coefficients of the logistic models were higher than 0.943,indicating that our results were effective in the simulation of the growth curves.ANOVA analysis showed significant differences in height of different clones （P／0.01）.Average date of maximum height growth was Day 173,and average duration of rapid growth lasted for 50 days.Annual average increase in height was 9.7cm d^（-1） and daily average increase was 0.2 cm.The ratio of GR to the total annual increase in height ranged from 51.2 to 68.8%,with the average being 59.8%.There was a positive correlation between k values and plant heights which benefited from the evaluation of early plant height.There was also a positive correlation between GR（growth stage）,GD（plant height） and annual increase in height.These results are informative to the evaluation of the elite clone selection and provide a theoretical basis for breeding and management.
文摘In order to avoid the UHVAC (Ultra High Voltage Alternating Current) transmission line with shunt reactor fault voltage smaller problems, through the analysis of single-phase permanent fault when tripping phase terminal voltage characteristics, this paper presents a fault phase voltage signal of the two order derivative and the original signal ratio of a new method for steady-state frequency discrimination single-phase permanent fault. The principle of this method is simple, and it can avoid the problem that the fault voltage caused by the installation of shunt reactor is small. The adaptability and correctness of the proposed method are verified by a large number of simulations.
基金Zhejiang Provincial Natural Science of China (Grant No.LQ20E060003)Zhejiang Provincial Basic Public Welfare Research Project of China (Grant No.LGG20E050007)+3 种基金Key Projects of Hangzhou Agricultural and Social Development Research Program of China (Grant No.20212013B04)Projects of Hangzhou Agricultural and Social Development Research Program of China (Grant Nos.20201203B128,20212013B04)Scientific Research Foundation of Zhejiang University City College of China (Grant Nos.J-202116,X-202205)2021 Teacher Professional Development Program for Domestic Visiting Scholars in Universities of China (Grant No.FX2021105)。
文摘The performance of an integrated thermal management system signi?cantly in?uences the stability of special-purpose vehicles;thus,enhancing the heat transfer of the radiator is of great signi?cance.Common research methods for radiators include?uid mechanics numerical simulations and experimental measurements,both of which are time-consuming and expensive.Applying the surrogate model to the analysis of the?ow and heat transfer in louvered?ns can effectively reduce the computational cost and obtain more data.A simpli?ed louvered-?n heat transfer unit was established,and computational?uid dynamics(CFD)simulations were conducted to obtain the?ow and heat transfer characteristics of the geometric structure.A three-factor and six-level orthogonal design was established with three structural parameters:angleθ,length a,and pitch L_p of the louvered?ns.The results of the orthogonal design were subjected to a range analysis,and the effects of the three parametersθ,a,and L_p on the j,f,and JF factors were obtained.Accordingly,a proxy model of the heat transfer performance for louvered?ns was established based onthe arti?cial neural network algorithm,and the model was trained with the data obtained by the orthogonal design.Finally,the?n structure with the largest JF factor was realized.Compared with the original model,the optimizedmodel improved the heat transfer factor j by 2.87%,decreased the friction factor f by 30.4%,and increased the comprehensive factor JF by 15.7%.
基金support by the National SKA Program of ChinaNo.2022SKA0110100+1 种基金the CAS Interdisciplinary Innovation Team(JCTD-2019-05)the science research grants from the China Manned Space Project with No.CMS-CSST-2021-B01。
文摘In the neutral hydrogen(H I)galaxy survey,a significant challenge is to identify and extract the H I galaxy signal from the observational data contaminated by radio frequency interference(RFI).For a drift-scan survey,or more generally a survey of a spatially continuous region,in the time-ordered spectral data,the H I galaxies and RFI all appear as regions that extend an area in the time-frequency waterfall plot,so the extraction of the H I galaxies and RFI from such data can be regarded as an image segmentation problem,and machine-learning methods can be applied to solve such problems.In this study,we develop a method to effectively detect and extract signals of H I galaxies based on a Mask R-CNN network combined with the PointRend method.By simulating FAST-observed galaxy signals and potential RFI impact,we created a realistic data set for the training and testing of our neural network.We compared five different architectures and selected the best-performing one.This architecture successfully performs instance segmentation of H I galaxy signals in the RFI-contaminated time-ordered data,achieving a precision of 98.64%and a recall of 93.59%.
基金supported in part by the Teaching Reform Research Foundation of Shengli College in China University of Petroleum(East China)(JG201725)the Natural Science Foundation Shandong Province of China(ZR2018PEE009)the Project of Science and Technology of Shandong Universities in China(J17KA044,J17KB061)。
文摘Many effective optimization algorithms require partial derivatives of objective functions, while some optimization problems' objective functions have no derivatives. According to former research studies, some search directions are obtained using the quadratic hypothesis of objective functions. Based on derivatives, quadratic function assumptions, and directional derivatives, the computational formulas of numerical first-order partial derivatives, second-order partial derivatives, and numerical second-order mixed partial derivatives were constructed. Based on the coordinate transformation relation, a set of orthogonal vectors in the fixed coordinate system was established according to the optimization direction. A numerical algorithm was proposed, taking the second order approximation direction as an example. A large stepsize numerical algorithm based on coordinate transformation was proposed. Several algorithms were validated by an unconstrained optimization of the two-dimensional Rosenbrock objective function. The numerical second order approximation direction with the numerical mixed partial derivatives showed good results. Its calculated amount is 0.2843% of that of without second-order mixed partial derivative. In the process of rotating the local coordinate system 360°, because the objective function is more complex than the quadratic function, if the numerical direction derivative is used instead of the analytic partial derivative, the optimization direction varies with a range of 103.05°. Because theoretical error is in the numerical negative gradient direction, the calculation with the coordinate transformation is 94.71% less than the calculation without coordinate transformation. If there is no theoretical error in the numerical negative gradient direction or in the large-stepsize numerical optimization algorithm based on the coordinate transformation, the sawtooth phenomenon occurs. When each numerical mixed partial derivative takes more than one point, the optimization results cannot be improved. The numerical direction based on the quadratic hypothesis only requires the objective function to be obtained, but does not require derivability and does not take into account truncation error and rounding error. Thus, the application scopes of many optimization methods are extended.
基金supported by Zhejiang Provincial Natural Science of Foundation of China(No.LQ20B070005)the Fundamental Research Funds for the Central Universities(Nos.2019FZJD007 and 2019QNA6008)+1 种基金the National Natural Science Foundation of China(Nos.21876151 and 81703236)Project for Zhejiang Medical Technology Program(Nos.2018KY437,2016KYA049 and WKJ-ZJ-1621)
文摘Polycyclic aromatic hydrocarbons(PAHs)are a typical class of persistent organic pollutants that is ubiquitous worldwide.Previous animal studies suggested that PAHs had adverse effects on female reproduction.However,the human data regarding relationship of PAHs exposure with women reproductive health,such as ovarian dysfunction,are scarce.In this case-control study,the associations of serum levels of PAHs with the risk of premature ovarian failure(POF)and reproductive hormones in Chinese women were investigated,with recruiting 157 POF patients and 217 healthy women.The serum levels of 12 types of PAHs,as well as reproductive hormones,including follicle-stimulating hormone,luteinizing hormone and anti-mullerian hormone,were determined.In the logistic regression models,most individual PAH congeners showed significantly positive correlations with the risk of POF(p<0.05),except for fluorine and pyrene.Benzo(a)pyrene(BaP),as the most carcinogenic PAH congener,was observed to be significantly positively associated with the risk of POF.After adjustment for age,body mass index,educational levels and household income,per one-unit increase in the log-transformed BaP concentration was significantly correlated with 2.191-fold increased risk of POF(OR=2.191,95%CI:1.634-2.938,p<0.05).To the best of our knowledge,this is the first study to report an association between internal exposure levels of PAHs and the increased risk of POF in women.
基金National Natural Science Foundation of China(Nos.41967019 and 41661077)the National Key Technologies Research and Development Program of China(No.2017YFD0801500)+1 种基金the Guangxi Science and Technology Development Project of Major Projects of Guangxi(Guike AA17204047-3)Scientific Research and Technology Development Program of Guilin(Nos.20190205 and 20180107-3).
文摘The current study evaluated the effects of oxalic acid(OA)application on the growth and Mn phytoremediation efficiency of Polygonum pubescens Blume cultivated in three different manganese(Mn)-contaminated soils sampled from an unexplored area(US),an explored area(ES)and a tailing area(TS)of the Ertang Mn mine,South China.The supplied levels of OA were 0(control),1(low level),3(medium level),and 9(high level)mmol/kg,referred to as CK,OA1,OA3 and OA9,respectively.The results revealed that the average water-extractable Mn concentrations US,ES and TS amended with OA increased by 214.13,363.77 and 266.85%,respectively.All OA supply levels increased plant growth and Mn concentrations in US.The low OA supply level increased plant growth in ES and TS;however,contrasting results were found for the medium and high OA supply levels.Plant Mn concentrations and total Mn increased in ES and TS in response to all OA supply levels.Total Mn in the aerial parts increased by 81.18,44.17 and 83.17%in US,ES and TS,respectively;the corresponding percentages for the whole plants were 81.53,108.98 and 77.91%,respectively.The rate of·O_(2)^(−)production and malondialdehyde(MDA)concentrations increased in response to OA amendment,especially the medium and high OA supply levels in ES and TS.In general,antioxidant enzymes might play a vital role in alleviating Mn stress in plants cultivated in US,while non-enzymatic antioxidants might be the main factor for plants cultivated in ES and TS.
基金The authors would like to acknowledge the support from the Innovation Program(2370990000-00170004)the National Natural Science Foundation of China(91860112)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB22020200).
文摘The probabilistic control volume method has great prospects in correlating the effects of specimen size,notch and loading type on fatigue life or fatigue strength.In this work,the effects of notch size and loading type on fatigue life are investigated by using the probabilistic control volume method.Rotating bending and axial loading fatigue te«t«are at first performed on the hourglass specimen,circumferential V-notch specimen and V-notch plate specimen of 30CrMnSiA steel.Experimental results indicate that the notch reduces the fatigue strength of specimens in terms of nominal stress amplitude while in terms of local stress amplitude,the notch specimen could endure higher fatigue strength.Then,the probabilistic control volume method is used to evaluate the effects of notch size and loading type on fatigue life.It is shown that the probabilistic control volume method correlates well the effects of notch size and loading type on fatigue life,even for the local stress of the notch root exceeding the yield stress of the material.
基金supported by the National Natural Science Foundation of China(Grant No.41967019)the National Social Science Foundation Project of China(No.16BTQ033).
文摘In total,9,552 documents were extracted from the Web of Science Core Collection and subjected to knowledge mapping and visualization analysis for the field of phytoremediation of HM-contaminated soil(PHMCS)with CiteSpace 5.7 R3 software.The results showed that(1)the number of publications increased linearly over the studied period.The top 10 countries/regions,institutions and authors contributing to this field were exhibited.(2)Keyword co-occurrence cluster analysis revealed a total of 8 clusters,including“Bioremediation,”“Arsenic,”“Biochar,”“Oxidative stress,”“Hyperaccumulation,”“EDTA,”“Arbuscular mycorrhizal fungi,”and“Environmental pollution”clusters(3)In total,334 keyword bursts were obtained,and the 25 strongest,longest duration,and newest keyboard bursts were analyzed in depth.The strongest keyword burst test showed that the hottest keywords could be divided into 7 groups,i.e.,“Plant bioremediation materials,”“HM types,”“Chelating amendments,”“Other improved strategies,”“Bioremediation characteristics,”“Risk assessment,”and“Other.”Almost half of the newest topics had emerged in the past 3 years,including“biochar,”“drought,”“health risk assessment,”“electrokinetic remediation,”“nanoparticle,”and“intercropping.”(4)In total,9 knowledge base clusters were obtained in this study.The studies of Ali et al.(2013),Blaylock et al.(1997),Huang et al.(1997),van der Ent et al.(2013),Salt et al.(1995),and Salt(1998),which had both high frequencies and the strongest burst scores,have had the most profound effects on PHMCS research.Finally,future research directions were proposed.
基金This project was supported by the Key Technologies Research and Development Program of China(No.2017YFD0801500)National Natural Science Foundation of China(Grant Nos.41661077 and 41967019)+2 种基金Guangxi Science and Technology Development Project of Major Projects of Guangxi(Guike AA17204047-3)Guangxi Natural Science Foundation(No.2018JJA150018)We thank American Journal Experts(AJE)for editing the manuscript.
文摘Nutrient status and pollution levels are the main factors affecting soil restoration.The nutrient status and pollution levels in five areas,an unexplored mine area(UA),an explored mine area(EA),a tailings area(TA),a reclamation area(RA)and an agricultural area(AA),around the Pingle manganese mine in Guangxi,China,were assessed in this study.The results showed that the average total phosphorus in these five areas ranged from 1.05 to 1.57 mg/kg,corresponding to grades of extremely high and high.The average total nitrogen values were 0.19,0.69,0.93,1.24 and 1.67 mg/kg in EA,TA,RA,UA and AA,corresponding to grades of very low,low,medium-low,medium-high and medium-high,respectively.The average organic matter values were 12.78,8.92,22.77,21.29 and 29.11 mg/kg in EA,TA,RA,UA and AA,which corresponded to grades of medium-low,low,medium-high,medium-high and medium-high,respectively.All these results indicated that the total phosphorus was sufficient in these areas,while the total nitrogen and organic matter were insufficient in EA,TA and RA.The available concentrations of Mn and Zn corresponded to the intermediate grade,while the values for Cu corresponded to the very low grade;these might be another factor restricting ecological reclamation.Contamination and ecological risk assessments based on the single contamination index,Nemerow multi-factor index and potential ecological risk index showed that the five tested areas around the Mn mine were considered heavily polluted and presented high ecological risk.Mn and Cd were the dominant pollutants.
基金financially supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Nos.KZCX2-YW-453,KZCX2-YW-JS404,and KZCX2-EW-408)the National Natural Science Foundation of China(No.41005082)the Commonweal Program of Environment Protection Department of China(No.201009004)
文摘Atmospheric fine particles （PM2.5） were collected in this study with middle volume samplers in Fuzhou, China, during both normal days and haze days in summer （September 2007） and winter （january 2008）. The concentrations, distributions, and sources of polycyclic aromatic hydrocarbons （PAHs）, organic carbon （OC）, elemental carbon （EC）, and water soluble inorganic ions （WSIls） were determinated. The results showed that the concentrations of PM2.s, PAHs, OC, EC, and WSIIs were in the orders of haze 〉 normal and winter〉 summer. The dominant PAHs of PM2.s in Fuzhou were Fluo, Pyr, Chr, BbF, BkF, BaP, BghiP, and IcdP, which represented about 80.0% of the total PAHs during different sampling periods. The BaPeq concentrations of ^-~PAHs were 0.78, 0.99, 1.22, and 2.43 ng/m3 in summer normal, summer haze, winter normal, and winter haze, respectively. Secondary pollutants （SO42 , NO3 , NH4＊, and OC） were the major chemical compositions of PM2.5, accounting for 69.0%, 55.1%, 63.4%, and 64.9% of PM2.s mass in summer normal, summer haze, winter normal, and winter haze, respectively. Correspondingly, secondary organic carbon （SOC） in Fuzhou accounted for 20.1%, 48.6%, 24.5%, and 50.5% of OC. The average values of nitrogen oxidation ratio （NOR） and sulfur oxidation ratio （SOR） were higher in haze days （0.08 and 0.27） than in normal days （0.05 and 0.22）. Higher OC/EC ratios were also found in haze days （5.0） than in normal days （3.3）. Correlation analysis demonstrated that visibility had positive correlations with wind speed, and neg- ative correlations with relative humidity and major air pollutants. Overall, the enrichments of PM2.5, OC, EC, SO42 ,andNO3 promoted haze formation. Furthermore, the diagnostic ratios of IcdP/（IcdP ＋ BghiP）, lcdP/BghiP, OC/EC, and NO3 /SO42 indicated that vehicle exhaust and coal consumption were the main sources of pollutants in Fuzhou.
基金supported by the National Natural Science Foundation of China(No.50801027)Public Foundation of Guangdong Key Laboratory for Advanced Metallic Materials Processing, South China University of Technology, China(No.2007001)
文摘In the present investigation a wrought magnesium alloy AZ31 was successfully processed by the accumulative roll-bonding （ARB） at gradient temperature up to six cycles with the lowest temperature of 250 °C. This is performed through different thermomechanical processing routes （different ARB cycles at different temperatures of 350-200 °C）. The microstructures and mechanical properties were investigated. The results indicate that significant grain refinement is observed after the first two cycles at the highest ARB temperature as a result of dynamic recrystallization, which is necessary for the subsequently ARB cycles at relatively lower temperature with the aim to restrict grain growth. No significant finer grain size was observed through the fifth and sixth cycles while the microstructure homogeneity is further improved. The grain structure can be effectively refined at lower ARB processing temperature and higher cycles. The resulting material exhibited high strength and relatively high ductility at ambient temperature when ARB deformed above 250 °C. The mechanical properties of the ARB deformed materials are strongly dependent on several main factors： the amount and the homogeneity of strain achieved, grain size and microstructure homogeneity, textures developed during ARB and interface bonding quality.
