Metastasis is responsible for the majority of deaths among breast cancer patients.Although parallel polyclonal seeding has been shown to contribute to organ-specific metastasis,in the past decade,horizontal cross-meta...Metastasis is responsible for the majority of deaths among breast cancer patients.Although parallel polyclonal seeding has been shown to contribute to organ-specific metastasis,in the past decade,horizontal cross-metastatic seeding(metastasis-to-metastasis spreading)has also been demonstrated as a pattern of distant metastasis to multiple sites.Bone,as the most frequent first destination of breast cancer metastasis,has been demonstrated to facilitate the secondary dissemination of breast cancer cells.In this review,we summarize the clinical and experimental evidence that bone is a transfer station for the secondary dissemination of breast cancer.We also discuss the regulatory mechanisms of the bone microenvironment in secondary seeding of breast cancer,focusing on stemness regulation,quiescence-proliferation equilibrium regulation,epigenetic reprogramming and immune escape of cancer cells.Furthermore,we highlight future research perspectives and strategies for preventing secondary dissemination from bone.展开更多
Objectives: We hypothesized that the organisms and their organs or tissues could adapt themselves to the gradual changes of environment for surviving or reducing damage. This study explored whether gradual clamping (G...Objectives: We hypothesized that the organisms and their organs or tissues could adapt themselves to the gradual changes of environment for surviving or reducing damage. This study explored whether gradual clamping (GC) could reduce myocardial ischemia-reperfusion (IR) injury in rat heart. Methods: Twelve rats were randomized to IR group and GC group, then the hearts were isolated and perfused with Langendorff apparatus. Before cardioplegia, the perfusion was stopped abruptly in IR group while slowly with 5-minute in GC group. The hearts were subjected to 30-minute ischemia and 60-minute reperfusion. The left ventricular develop pressure (LVDP) and systolic pressure (LVSP), the maximal rate of the increase and decrease of left ventricular pressure (+dp/dt<sub>max</sub>, ﹣dp/dt<sub>max</sub>) were measured by polygraph system at different time points. The recovery of the variables was expressed as the ratio of these values at individual time point after reperfusion to the baseline respectively. Results: The recovery of LVDP after reperfusion was better than that in IR group (P = 0.034). No significant difference in the recovery of LVSP, +dp/dtmax and ﹣dp/dt<sub>max</sub> between groups was observed. Conclusions: Gradual clamping could improve the recovery of LVDP after IR, suggesting that gradual clamping could reduce myocardial IR injury.展开更多
The Ensemble Transform(ET) method has been shown to be useful in providing guidance for adaptive observation deployment.It predicts forecast error variance reduction for each possible deployment using its correspond...The Ensemble Transform(ET) method has been shown to be useful in providing guidance for adaptive observation deployment.It predicts forecast error variance reduction for each possible deployment using its corresponding transformation matrix in an ensemble subspace.In this paper,a new ET-based sensitivity(ETS) method,which calculates the gradient of forecast error variance reduction in terms of analysis error variance reduction,is proposed to specify regions for possible adaptive observations.ETS is a first order approximation of the ET;it requires just one calculation of a transformation matrix,increasing computational efficiency(60%-80%reduction in computational cost).An explicit mathematical formulation of the ETS gradient is derived and described.Both the ET and ETS methods are applied to the Hurricane Irene(2011) case and a heavy rainfall case for comparison.The numerical results imply that the sensitive areas estimated by the ETS and ET are similar.However,ETS is much more efficient,particularly when the resolution is higher and the number of ensemble members is larger.展开更多
As Volatile Organic Compounds(VOCs)are one of the precursors of ozone,their distribution and variable concentrations are highly related to local ozone pollution control.In this study,we obtained vertical profiles of V...As Volatile Organic Compounds(VOCs)are one of the precursors of ozone,their distribution and variable concentrations are highly related to local ozone pollution control.In this study,we obtained vertical profiles of VOCs in Shanghai’s Jinshan district on 8 September and 9 September in 2016 to investigate their distribution and impact on local atmospheric oxidation in the near surface layer.Vertical samples were collected from heights between 50 m and 400 m by summa canisters using an unmanned aerial vehicle(UAV).Concentrations of VOCs(VOCs refers to the 52 species measured in this study)varied minimally below 200 m,and decreased by 21.2%from 100 m to 400 m.The concentrations of VOCs above 200 m decreased significantly in comparison to those below 200 m.The proportions of alkanes and aromatics increased from 55.2%and 30.5%to 57.3%and 33.0%,respectively.Additionally,the proportion of alkenes decreased from 13.2%to 8.4%.Toluene and m/p-xylene were the key species in the formation of SOA and ozone.Principal component analysis(PCA)revealed that the VOCs measured in this study mainly originated from industrial emissions.展开更多
<b>Objective:</b> <i>Angiostrongylus cantonensis</i> (<i>A. cantonensis</i>) is an important parasite, which causes neurological infection in children, and is generally difficult to...<b>Objective:</b> <i>Angiostrongylus cantonensis</i> (<i>A. cantonensis</i>) is an important parasite, which causes neurological infection in children, and is generally difficult to diagnose. We analyzed the significance of metagenomic next-generation sequencing in diagnosing <i>A. cantonensis</i> encephalitis/meningitis in children to provide a reference for clinical diagnosis. <b>Methods:</b> The case collection of <i>A. cantonensis</i> encephalitis/meningitis was from July 2018 to August 2020. The patients’ clinical characteristics and pathogen were described, and diagnostic sensitivity methods for <i>A. cantonensis</i> encephalitis/meningitis were compared and analyzed, including parasite antibody detection and metagenomic next-generation sequencing (mNGS) detection in different samples. <b>Results:</b> Eleven cases were diagnosed with <i>A. cantonensis</i> encephalitis/meningitis, including six males (54.5%) and five females (45.5%), and the age ranged from 1 to 13 years with a median of 21 months (IQR: 15.6, 96). All patients were undiagnosed upon admission, of which ten cases had neurological symptoms or signs, six cases (54.5%) had a history of definite or suspicious exposure to parasites, and eight cases (72.7%) had abnormal changes in cranial MRI. The results of <i>A. cantonensis</i> antibodies in the peripheral blood and cerebrospinal fluid (CSF) were compared with CSF’s metagenomic next-generation sequencing (mNGS). The antibody-positive rate of peripheral blood was 54.5%, CSF antibody-positive rate was 27.2%, and mNGS-positive rate of CSF was 81.8%, and the positive diagnostic rate of the latter was significantly higher than the former two (<i>p</i> = 0.035 < 0.05 and <i>p</i> = 0.030 < 0.05, respectively). <b>Conclusion:</b> Metagenomic next-generation sequencing has a higher positive rate for diagnosing infection and plays an important role in clarifying diagnosis and reducing misdiagnosis.展开更多
This paper focuses on synthesizing a mixed robust H_2/H_∞ linear parameter varying(LPV) controller for the longitudinal motion of an air-breathing hypersonic vehicle via a high order singular value decomposition(H...This paper focuses on synthesizing a mixed robust H_2/H_∞ linear parameter varying(LPV) controller for the longitudinal motion of an air-breathing hypersonic vehicle via a high order singular value decomposition(HOSVD) approach.The design of hypersonic flight control systems is highly challenging due to the enormous complexity of the vehicle dynamics and the presence of significant uncertainties.Motivated by recent results on both LPV control and tensor-product(TP) model transformation approach,the velocity and altitude tracking control problems for the air-breathing hypersonic vehicle is reduced to that of a state feedback stabilizing controller design for a polytopic LPV system with guaranteed performances.The controller implementation is converted into a convex optimization problem with parameterdependent linear matrix inequalities(LMIs) constraints,which is intuitively tractable using LMI control toolbox.Finally,numerical simulation results demonstrate the effectiveness of the proposed approach.展开更多
The Ensemble Transformation(ET)method and its variation ET-based Sensitivity(ETS)method have been used in adaptive observation studies.However,the solution of the ensemble transformation matrix in the ET and ETS metho...The Ensemble Transformation(ET)method and its variation ET-based Sensitivity(ETS)method have been used in adaptive observation studies.However,the solution of the ensemble transformation matrix in the ET and ETS methods is not unique.A general mathematical formulation for the ensemble transformation matrix is derived and then a generalized equation for the ETS method is derived.It is proved that the previous ETS formulation is a special implementation of the newly derived general formulation.Another practicable implementation of the general ETS formulation that avoids calculating the inverse of some matrices is proposed.This ETS implementation showed physically reasonable statistical sensitivity regions for improving 1–3 day weather forecasts over eastern regions of U.S.A and Beijing region,China.展开更多
Angiogenin is associated with the pathogenesis of diabetic peripheral neuropathy. Here, we se- quenced the coding region of the angiogenin gene in genomic DNA from 207 patients with type 2 diabetes mellitus (129 diab...Angiogenin is associated with the pathogenesis of diabetic peripheral neuropathy. Here, we se- quenced the coding region of the angiogenin gene in genomic DNA from 207 patients with type 2 diabetes mellitus (129 diabetic peripheral neuropathy patients and 78 diabetic non-neuropathy pa- tients) and 268 healthy controls. All subjects were from the Han population of northern China. No mutations were found. We then compared the genotype and allele frequencies of the angiogenin synonymous single nucleotide polymorphism rs11701 between the diabetic peripheral neuropathy patients and controls, and between the diabetic neuropathy and non-neuropathy patients, using a case-control design. We detected no statistically significant genetic associations. Angiogenin may not be associated with genetic susceptibility to diabetic peripheral neuropathy in the Han population of northern China.展开更多
In this paper,unipolar pulse(including positive pulse and negative pulse)and bipolar pulse voltage are employed to generate diffuse gas–liquid discharge in atmospheric N2with a rumpetshaped quartz tube.The current–v...In this paper,unipolar pulse(including positive pulse and negative pulse)and bipolar pulse voltage are employed to generate diffuse gas–liquid discharge in atmospheric N2with a rumpetshaped quartz tube.The current–voltage waveforms,optical emission spectra of excited state active species,FTIR spectra of exhaust gas components,plasma gas temperature,and aqueous H2O2,NO2-,andNO3-production are compared in three pulse modes,meanwhile,the effects of pulse peak voltage and gas flow rate on the production of reactive species are studied.The results show that two obvious discharges occur in each voltage pulse in unipolar pulse driven discharge,differently,in bipolar pulse driven discharge,only one main discharge appears in a single voltage pulse time.The intensities of active species(OH(A),and O(3p))in all three pulsed discharge increase with the rise of pulse peak voltage and have the highest value at 200 ml min-1of gas flow rate.The absorbance intensities of NO2and N2O increase with the increase of pulse peak voltage and decrease with the increase of gas flow rate.Under the same discharge conditions,the bipolar pulse driven discharge shows lower breakdown voltage,and higher intensities of excited species(N2(C),OH(A),and O(3p)),nitrogen oxides(NO2,NO,and N2O),and higher production of aqueous H2O2,NO2-,andNO3-compared with both unipolar positive and negative discharges.展开更多
The branching system of higher plants plays a very important role in plant morphogenesis,and the number of branches can directly affect crop yield and the ornamental value of plants.It is a complicated development pro...The branching system of higher plants plays a very important role in plant morphogenesis,and the number of branches can directly affect crop yield and the ornamental value of plants.It is a complicated development process involving complex molecular mechanisms.The‘Cailinghong’variety of Salvia splendens is characterized by its great branching ability with the ability to grow into a spherical form naturally,without pinching.To gain insight into the molecular events during the branching development of S.splendens,suppressive subtractive hybridization(SSH)technology was used to screen differentially expressed genes between the erect plant type(strain 35)and the spherical plant type(‘Cailinghong’).In total,96 and 116 unigenes were annotated.Four and eight unigenes up-regulated in‘Cailinghong’and strain 35,respectively,were associated with plant hormone anabolism and signal transduction,suggesting that they participate in the branching process.One of these genes,phytoene synthase(PSY),is a precursor of the new plant hormone group strigolactones.Using the PSY fragment(192 bp)as a template,the cDNA sequence of PSY in S.splendens was cloned and named SsPSY.A relative expression analysis and transgenic test results indicated that SsPSY plays an important role in lateral branch development in‘Cailinghong’.These results provide new insight into the molecular mechanisms underlying branching in S.splendens.展开更多
In recent years,the development trend of passion fruit seedling industry in Qinzhou,Guangxi is good,but on the whole,it is still in its infancy and the development of the industry is fragile.This paper briefly describ...In recent years,the development trend of passion fruit seedling industry in Qinzhou,Guangxi is good,but on the whole,it is still in its infancy and the development of the industry is fragile.This paper briefly described the development status and existing problems of the passion fruit seedling industry in Qinzhou,Guangxi,and put forward reasonable suggestions in order to promote the healthy development of the passion fruit seedling industry,increase farmers’income and prosper rural economy.展开更多
Donald Barthelme, known as the pioneer ofpostmodernism, is not a serious, straight-ahead writer. He delights in ambiguity, juxtaposition, found texts, old words, old pictures and focused irony. This paper is to apply ...Donald Barthelme, known as the pioneer ofpostmodernism, is not a serious, straight-ahead writer. He delights in ambiguity, juxtaposition, found texts, old words, old pictures and focused irony. This paper is to apply the text analysis to one of his best work The Glass Mountain and explore the reality behind the absurd story and writing style.展开更多
The search for a promising career position is very difficult and highly competitive and an appealing well-written job application letter is its crucial first step. This paper is to apply the latest genre analysis appr...The search for a promising career position is very difficult and highly competitive and an appealing well-written job application letter is its crucial first step. This paper is to apply the latest genre analysis approach to 40-job-application-letter corpus. The analysis is essentially pragmatic-oriented in that its findings will not only benefit those who try to teach students how to write job application letters, but also offer genre analysis practitioners some valuable insights into the latest development of their research focus.展开更多
Extreme drought events have increased,causing serious losses and damage to the social economy under current warming conditions.However,short-term meteorological data limit our understanding and projection of these ext...Extreme drought events have increased,causing serious losses and damage to the social economy under current warming conditions.However,short-term meteorological data limit our understanding and projection of these extremes.With the accumulation of proxy data,especially tree-ring data,large-scale precipitation field reconstruction has provided opportunities to explore underlying mechanisms further.Using point-by-point regression,we reconstructed the April-September precipitation field in China for the past~530 years on the basis of 590 proxy records,including 470 tree-ring width chronologies and 120 drought/flood indices.Our regression models explained average 50%of the variance in precipitation.In the statistical test on calibration and verification,our models passed the significance level that assured reconstruction quality.The reconstruction data performed well,showing consistency and better quality than previously reported reconstructions.The first three leading modes of variability in the reconstruction revealed the main distribution modes of precipitation over China.Wet/drought and extremely wet/drought years accounted for 12.81%/10.92%(68 years/58 years)and 1.69%/3.20%(9 years/17 years)of the past~530 years in China,respectively.Major extreme drought events can be identified explicitly in our reconstruction.The detailed features of the Chongzhen Great Drought(1637-1643),the Wanli Great Drought(1585-1590),and the Ding-Wu Great Famine(1874-1879),indicated the existence of potentially different underlying mechanisms that need further exploration.Although further improvements can be made for remote uninhabited areas and large deserts,our gridded reconstruction of April-September precipitation in China over the past~530 years can provide a solid database for studies on the attribution of climate change and the mechanism of extreme drought events.展开更多
PM_(2.5)concentrations have dramatically reduced in key regions of China during the period 2013-2017,while O_(3)has increased.Hence there is an urgent demand to develop a synergetic regional PM_(2.5)and O_(3)control s...PM_(2.5)concentrations have dramatically reduced in key regions of China during the period 2013-2017,while O_(3)has increased.Hence there is an urgent demand to develop a synergetic regional PM_(2.5)and O_(3)control strategy.This study develops an emission-to-concentration response surface model and proposes a synergetic pathway for PM_(2.5)and O_(3)control in the Yangtze River Delta(YRD)based on the framework of the Air Benefit and Cost and Attainment Assessment System(ABaCAS).Results suggest that the regional emissions of NOx,SO_(2),NH3,VOCs(volatile organic compounds)and primary PM_(2.5)should be reduced by 18%,23%,14%,17%and 33%compared with 2017 to achieve 25%and 5% decreases of PM_(2.5)and O_(3)in 2025,and that the emission reduction ratios will need to be 50%,26%,28%,28% and 55%to attain the National Ambient Air Quality Standard.To effectively reduce the O_(3) pollution in the central and eastern YRD,VOCs controls need to be strengthened to reduce O_(3)by 5%,and then NOx reduction should be accelerated for air quality attainment.Meanwhile,control of primary PM_(2.5)emissions shall be prioritized to address the severe PM_(2.5)pollution in the northern YRD.For most cities in the YRD,the VOCs emission reduction ratio should be higher than that for NOx in Spring and Autumn.NOx control should be increased in summer rather than winter when a strong VOC-limited regime occurs.Besides,regarding the emission control of industrial processes,on-road vehicle and residential sources shall be prioritized and the joint control area should be enlarged to include Shandong,Jiangxi and Hubei Province for effective O_(3)control.展开更多
Monocyclic aromatic hydrocarbons(MAHs)and polycyclic aromatic hydrocarbons(PAHs)are both well known as hazardous air pollutants and also important anthropogenic precursors of tropospheric ozone(O3)and secondary organi...Monocyclic aromatic hydrocarbons(MAHs)and polycyclic aromatic hydrocarbons(PAHs)are both well known as hazardous air pollutants and also important anthropogenic precursors of tropospheric ozone(O3)and secondary organic aerosols(SOA).In recent years,there have been intensive studies covering MAHs emission from various sources and their behavior under stimulated photochemical conditions.Yet in-situ measurements of PAHs presence and variations in ambient air are sparse.Herein we conducted large geometrical scale mobile measurements for 16 aromatic hydrocarbons(AHs,including 7 MAHs and 9 PAHs)in eastern China between October 27 and November 8,2019.This unique dataset has allowed for some insights in terms of AHs concentration variations,accompanying chemical composition,source contributions and spatial distributions in eastern China.In general,AHs showed a clear concentration variability between the south and the north of the Yangtze River Delta(YRD).The concentrations of PAHs were approximately 9%of AHs,but contributed 23%of SOA formation potential.Source apportionment via positive matrix factorization(PMF)model revealed that industrial processes as the largest source(44%)of observed AHs,followed by solvent usage(21%),vehicle exhaust(19%),coal combustion(11%)and coking processes(6%).In the perspective of PAHs sources,coal combustion emissions were identified as the dominating factor of a share of 41%–52%in eastern China.Our findings complemented the simultaneously monitoring information of PAHs and MAHs in eastern China,revealed the importance of PAHs to SOA formation and highlighted the necessity of formulating strategies to reduce emissions from anthropogenic sources and reduce risks to human health.展开更多
Fabricating an efficient charge transfer pathway at the compact interface between two kinds of semiconductors is an important strategy for designing hydrogen production heterojunction photocatalysts.In this work,we pr...Fabricating an efficient charge transfer pathway at the compact interface between two kinds of semiconductors is an important strategy for designing hydrogen production heterojunction photocatalysts.In this work,we prepared a compact,stable and oxygen vacancy-rich photocatalyst(SnO_(2)/TiO_(2) heterostructure)via a simple and reasonable in-situ synthesis method.Briefly,SnCl_(2)–2H_(2)O is hydrolyzed on the TiO_(2) precursor.After the pyrolysis process,SnO_(2) nanoparticles(5 nm)were dispersed on the surface of ultrathin TiO_(2) nanosheets uniformly.Herein,the heterojunction system can offer abundant oxygen vacancies,which can act as active sites for catalytic reactions.Meanwhile,the interfacial contact of SnO_(2)/TiO_(2) grading semiconductor oxide is uniform and tight,which can promote the separation and migration of photogenerated carriers.As shown in the experimental results,the hydrogen production rate of SnO_(2)/TiO_(2) is 16.7 mmol h^(-1)g^(-1)(4.4 times higher than that of TiO_(2)),which is owing to its good dynamical properties.This work demonstrates an efficient strategy of tight combining SnO_(2)/TiO_(2) with abundant oxygen vacancies to improve catalytic efficiency.展开更多
Heterogeneous reaction of NO_(2) with mineral dust aerosol may play important roles in troposphere chemistry,and has been investigated by a number of laboratory studies.However,the influence of mineralogy on this reac...Heterogeneous reaction of NO_(2) with mineral dust aerosol may play important roles in troposphere chemistry,and has been investigated by a number of laboratory studies.However,the influence of mineralogy on this reaction has not been well understood,and its impact on aerosol hygroscopicity is not yet clear.This work investigated heterogeneous reactions of NO_(2)(∼10 ppmv)with K-feldspar,illite,kaolinite,montmorillonite and Arizona Test Dust(ATD)at room temperature as a function of relative humidity(<1%to 80%)and reaction time(up to 24 hr).Heterogeneous reactivity towards NO_(2) was low for illite,kaolinite,montmorillonite and ATD,and uptake coefficients of NO_(2),γ(NO_(2)),were determined to be around or smaller than 1×10^(−8);K-feldspar exhibited higher reactivity towards NO_(2),and CaCO_(3) is most reactive among the nine mineral dust samples considered in this and previous work.After heterogeneous reaction with NO_(2) for 24 hr,increase in hygroscopicity was nearly insignificant for illite,kaolinite and montmorillonite,and small but significant for K-feldspar;in addition,large increase in hygroscopicity was observed for ATD,although the increase in hygroscopicity was still smaller than CaCO_(3).展开更多
基金supported by the National Natural Science Foundation of China(Nos.82273285 and 81672878)Tianjin Key Medical Discipline(Specialty)Construction Project(TJYXZDXK-009A)。
文摘Metastasis is responsible for the majority of deaths among breast cancer patients.Although parallel polyclonal seeding has been shown to contribute to organ-specific metastasis,in the past decade,horizontal cross-metastatic seeding(metastasis-to-metastasis spreading)has also been demonstrated as a pattern of distant metastasis to multiple sites.Bone,as the most frequent first destination of breast cancer metastasis,has been demonstrated to facilitate the secondary dissemination of breast cancer cells.In this review,we summarize the clinical and experimental evidence that bone is a transfer station for the secondary dissemination of breast cancer.We also discuss the regulatory mechanisms of the bone microenvironment in secondary seeding of breast cancer,focusing on stemness regulation,quiescence-proliferation equilibrium regulation,epigenetic reprogramming and immune escape of cancer cells.Furthermore,we highlight future research perspectives and strategies for preventing secondary dissemination from bone.
文摘Objectives: We hypothesized that the organisms and their organs or tissues could adapt themselves to the gradual changes of environment for surviving or reducing damage. This study explored whether gradual clamping (GC) could reduce myocardial ischemia-reperfusion (IR) injury in rat heart. Methods: Twelve rats were randomized to IR group and GC group, then the hearts were isolated and perfused with Langendorff apparatus. Before cardioplegia, the perfusion was stopped abruptly in IR group while slowly with 5-minute in GC group. The hearts were subjected to 30-minute ischemia and 60-minute reperfusion. The left ventricular develop pressure (LVDP) and systolic pressure (LVSP), the maximal rate of the increase and decrease of left ventricular pressure (+dp/dt<sub>max</sub>, ﹣dp/dt<sub>max</sub>) were measured by polygraph system at different time points. The recovery of the variables was expressed as the ratio of these values at individual time point after reperfusion to the baseline respectively. Results: The recovery of LVDP after reperfusion was better than that in IR group (P = 0.034). No significant difference in the recovery of LVSP, +dp/dtmax and ﹣dp/dt<sub>max</sub> between groups was observed. Conclusions: Gradual clamping could improve the recovery of LVDP after IR, suggesting that gradual clamping could reduce myocardial IR injury.
基金jointly sponsored by the Key Project of the Chinese National Programs for Fundamental Research and Development (“973 Program”, Grant No. 2013CB430106)the Key Project of the Chinese National Science & Technology Pillar Program during the Twelfth Five-year Plan Period (Grant No. 2012BAC22B01)
文摘The Ensemble Transform(ET) method has been shown to be useful in providing guidance for adaptive observation deployment.It predicts forecast error variance reduction for each possible deployment using its corresponding transformation matrix in an ensemble subspace.In this paper,a new ET-based sensitivity(ETS) method,which calculates the gradient of forecast error variance reduction in terms of analysis error variance reduction,is proposed to specify regions for possible adaptive observations.ETS is a first order approximation of the ET;it requires just one calculation of a transformation matrix,increasing computational efficiency(60%-80%reduction in computational cost).An explicit mathematical formulation of the ETS gradient is derived and described.Both the ET and ETS methods are applied to the Hurricane Irene(2011) case and a heavy rainfall case for comparison.The numerical results imply that the sensitive areas estimated by the ETS and ET are similar.However,ETS is much more efficient,particularly when the resolution is higher and the number of ensemble members is larger.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.41830106,21607104)the National Key Research and Development Plan(Grant Nos.2017YFC0210004,2018YFC0213801)+1 种基金the Shanghai Science and Technology Commission of Shanghai Municipality(18QA 403600)the Shanghai Environmental Protection Bureau(2017-2).
文摘As Volatile Organic Compounds(VOCs)are one of the precursors of ozone,their distribution and variable concentrations are highly related to local ozone pollution control.In this study,we obtained vertical profiles of VOCs in Shanghai’s Jinshan district on 8 September and 9 September in 2016 to investigate their distribution and impact on local atmospheric oxidation in the near surface layer.Vertical samples were collected from heights between 50 m and 400 m by summa canisters using an unmanned aerial vehicle(UAV).Concentrations of VOCs(VOCs refers to the 52 species measured in this study)varied minimally below 200 m,and decreased by 21.2%from 100 m to 400 m.The concentrations of VOCs above 200 m decreased significantly in comparison to those below 200 m.The proportions of alkanes and aromatics increased from 55.2%and 30.5%to 57.3%and 33.0%,respectively.Additionally,the proportion of alkenes decreased from 13.2%to 8.4%.Toluene and m/p-xylene were the key species in the formation of SOA and ozone.Principal component analysis(PCA)revealed that the VOCs measured in this study mainly originated from industrial emissions.
文摘<b>Objective:</b> <i>Angiostrongylus cantonensis</i> (<i>A. cantonensis</i>) is an important parasite, which causes neurological infection in children, and is generally difficult to diagnose. We analyzed the significance of metagenomic next-generation sequencing in diagnosing <i>A. cantonensis</i> encephalitis/meningitis in children to provide a reference for clinical diagnosis. <b>Methods:</b> The case collection of <i>A. cantonensis</i> encephalitis/meningitis was from July 2018 to August 2020. The patients’ clinical characteristics and pathogen were described, and diagnostic sensitivity methods for <i>A. cantonensis</i> encephalitis/meningitis were compared and analyzed, including parasite antibody detection and metagenomic next-generation sequencing (mNGS) detection in different samples. <b>Results:</b> Eleven cases were diagnosed with <i>A. cantonensis</i> encephalitis/meningitis, including six males (54.5%) and five females (45.5%), and the age ranged from 1 to 13 years with a median of 21 months (IQR: 15.6, 96). All patients were undiagnosed upon admission, of which ten cases had neurological symptoms or signs, six cases (54.5%) had a history of definite or suspicious exposure to parasites, and eight cases (72.7%) had abnormal changes in cranial MRI. The results of <i>A. cantonensis</i> antibodies in the peripheral blood and cerebrospinal fluid (CSF) were compared with CSF’s metagenomic next-generation sequencing (mNGS). The antibody-positive rate of peripheral blood was 54.5%, CSF antibody-positive rate was 27.2%, and mNGS-positive rate of CSF was 81.8%, and the positive diagnostic rate of the latter was significantly higher than the former two (<i>p</i> = 0.035 < 0.05 and <i>p</i> = 0.030 < 0.05, respectively). <b>Conclusion:</b> Metagenomic next-generation sequencing has a higher positive rate for diagnosing infection and plays an important role in clarifying diagnosis and reducing misdiagnosis.
基金supported by the National Natural Science Foundation of China(6120300761304239+1 种基金61503392)the Natural Science Foundation of Shaanxi Province(2015JQ6213)
文摘This paper focuses on synthesizing a mixed robust H_2/H_∞ linear parameter varying(LPV) controller for the longitudinal motion of an air-breathing hypersonic vehicle via a high order singular value decomposition(HOSVD) approach.The design of hypersonic flight control systems is highly challenging due to the enormous complexity of the vehicle dynamics and the presence of significant uncertainties.Motivated by recent results on both LPV control and tensor-product(TP) model transformation approach,the velocity and altitude tracking control problems for the air-breathing hypersonic vehicle is reduced to that of a state feedback stabilizing controller design for a polytopic LPV system with guaranteed performances.The controller implementation is converted into a convex optimization problem with parameterdependent linear matrix inequalities(LMIs) constraints,which is intuitively tractable using LMI control toolbox.Finally,numerical simulation results demonstrate the effectiveness of the proposed approach.
文摘The Ensemble Transformation(ET)method and its variation ET-based Sensitivity(ETS)method have been used in adaptive observation studies.However,the solution of the ensemble transformation matrix in the ET and ETS methods is not unique.A general mathematical formulation for the ensemble transformation matrix is derived and then a generalized equation for the ETS method is derived.It is proved that the previous ETS formulation is a special implementation of the newly derived general formulation.Another practicable implementation of the general ETS formulation that avoids calculating the inverse of some matrices is proposed.This ETS implementation showed physically reasonable statistical sensitivity regions for improving 1–3 day weather forecasts over eastern regions of U.S.A and Beijing region,China.
基金financially sponsored by the Natural Science Foundation of Beijing,No.7102161
文摘Angiogenin is associated with the pathogenesis of diabetic peripheral neuropathy. Here, we se- quenced the coding region of the angiogenin gene in genomic DNA from 207 patients with type 2 diabetes mellitus (129 diabetic peripheral neuropathy patients and 78 diabetic non-neuropathy pa- tients) and 268 healthy controls. All subjects were from the Han population of northern China. No mutations were found. We then compared the genotype and allele frequencies of the angiogenin synonymous single nucleotide polymorphism rs11701 between the diabetic peripheral neuropathy patients and controls, and between the diabetic neuropathy and non-neuropathy patients, using a case-control design. We detected no statistically significant genetic associations. Angiogenin may not be associated with genetic susceptibility to diabetic peripheral neuropathy in the Han population of northern China.
基金supported by National Natural Science Foundation of China(Nos.51977023,51677019,and 11965018)Fundamental Research Funds for the Central Universities in China(No.DUT18LK42)。
文摘In this paper,unipolar pulse(including positive pulse and negative pulse)and bipolar pulse voltage are employed to generate diffuse gas–liquid discharge in atmospheric N2with a rumpetshaped quartz tube.The current–voltage waveforms,optical emission spectra of excited state active species,FTIR spectra of exhaust gas components,plasma gas temperature,and aqueous H2O2,NO2-,andNO3-production are compared in three pulse modes,meanwhile,the effects of pulse peak voltage and gas flow rate on the production of reactive species are studied.The results show that two obvious discharges occur in each voltage pulse in unipolar pulse driven discharge,differently,in bipolar pulse driven discharge,only one main discharge appears in a single voltage pulse time.The intensities of active species(OH(A),and O(3p))in all three pulsed discharge increase with the rise of pulse peak voltage and have the highest value at 200 ml min-1of gas flow rate.The absorbance intensities of NO2and N2O increase with the increase of pulse peak voltage and decrease with the increase of gas flow rate.Under the same discharge conditions,the bipolar pulse driven discharge shows lower breakdown voltage,and higher intensities of excited species(N2(C),OH(A),and O(3p)),nitrogen oxides(NO2,NO,and N2O),and higher production of aqueous H2O2,NO2-,andNO3-compared with both unipolar positive and negative discharges.
基金the Special Project of the University in 2019-Capacity Building of Science and Technology Innovation Service-Construction of Scientific Research-Beijing Collaborative Innovation Center for Eco-Environmental Improvement with Forestry and Fruit Trees(2011 Collaborative Innovation Center)(Project No.CEFF-PXM2019_014207_000099)the National Natural Fund(Project No.31100509)+1 种基金Open Project of Beijing Engineering Research Center of Rural Landscape Planning and Design(KF2019065)General Project of Science and Technology Plan of Beijing Education Commission(KM202010020006).
文摘The branching system of higher plants plays a very important role in plant morphogenesis,and the number of branches can directly affect crop yield and the ornamental value of plants.It is a complicated development process involving complex molecular mechanisms.The‘Cailinghong’variety of Salvia splendens is characterized by its great branching ability with the ability to grow into a spherical form naturally,without pinching.To gain insight into the molecular events during the branching development of S.splendens,suppressive subtractive hybridization(SSH)technology was used to screen differentially expressed genes between the erect plant type(strain 35)and the spherical plant type(‘Cailinghong’).In total,96 and 116 unigenes were annotated.Four and eight unigenes up-regulated in‘Cailinghong’and strain 35,respectively,were associated with plant hormone anabolism and signal transduction,suggesting that they participate in the branching process.One of these genes,phytoene synthase(PSY),is a precursor of the new plant hormone group strigolactones.Using the PSY fragment(192 bp)as a template,the cDNA sequence of PSY in S.splendens was cloned and named SsPSY.A relative expression analysis and transgenic test results indicated that SsPSY plays an important role in lateral branch development in‘Cailinghong’.These results provide new insight into the molecular mechanisms underlying branching in S.splendens.
基金Supported by Science and Technology Pioneer"Strengthening Farmers and Enriching People"and"Six Ones"Special Action Project(GNKM 202104)Grassroots Agricultural Technology Extension Service Ability Improvement Project of Agriculture and Rural Affairs Department,Guangxi Zhuang Autonomous Region。
文摘In recent years,the development trend of passion fruit seedling industry in Qinzhou,Guangxi is good,but on the whole,it is still in its infancy and the development of the industry is fragile.This paper briefly described the development status and existing problems of the passion fruit seedling industry in Qinzhou,Guangxi,and put forward reasonable suggestions in order to promote the healthy development of the passion fruit seedling industry,increase farmers’income and prosper rural economy.
文摘Donald Barthelme, known as the pioneer ofpostmodernism, is not a serious, straight-ahead writer. He delights in ambiguity, juxtaposition, found texts, old words, old pictures and focused irony. This paper is to apply the text analysis to one of his best work The Glass Mountain and explore the reality behind the absurd story and writing style.
文摘The search for a promising career position is very difficult and highly competitive and an appealing well-written job application letter is its crucial first step. This paper is to apply the latest genre analysis approach to 40-job-application-letter corpus. The analysis is essentially pragmatic-oriented in that its findings will not only benefit those who try to teach students how to write job application letters, but also offer genre analysis practitioners some valuable insights into the latest development of their research focus.
基金National Key Research and Development Program of China(2018YFA0605601)Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20070101)National Natural Science Foundation of China(41572353,41401228,41690113)。
文摘Extreme drought events have increased,causing serious losses and damage to the social economy under current warming conditions.However,short-term meteorological data limit our understanding and projection of these extremes.With the accumulation of proxy data,especially tree-ring data,large-scale precipitation field reconstruction has provided opportunities to explore underlying mechanisms further.Using point-by-point regression,we reconstructed the April-September precipitation field in China for the past~530 years on the basis of 590 proxy records,including 470 tree-ring width chronologies and 120 drought/flood indices.Our regression models explained average 50%of the variance in precipitation.In the statistical test on calibration and verification,our models passed the significance level that assured reconstruction quality.The reconstruction data performed well,showing consistency and better quality than previously reported reconstructions.The first three leading modes of variability in the reconstruction revealed the main distribution modes of precipitation over China.Wet/drought and extremely wet/drought years accounted for 12.81%/10.92%(68 years/58 years)and 1.69%/3.20%(9 years/17 years)of the past~530 years in China,respectively.Major extreme drought events can be identified explicitly in our reconstruction.The detailed features of the Chongzhen Great Drought(1637-1643),the Wanli Great Drought(1585-1590),and the Ding-Wu Great Famine(1874-1879),indicated the existence of potentially different underlying mechanisms that need further exploration.Although further improvements can be made for remote uninhabited areas and large deserts,our gridded reconstruction of April-September precipitation in China over the past~530 years can provide a solid database for studies on the attribution of climate change and the mechanism of extreme drought events.
基金supported by the Key Projects of National Key Research and Development Program of the Ministry of Science and Technology of China(No.2018YFC0213805)Shanghai Science and Technology Commission Scientific Research Project(No.19DZ1205006)+2 种基金the National Natural Science Foundation of China(Nos.92044302 and 21625701)the Samsung Advanced Institute of Technologysupported by the Tencent Foundation through the Explorer Prize。
文摘PM_(2.5)concentrations have dramatically reduced in key regions of China during the period 2013-2017,while O_(3)has increased.Hence there is an urgent demand to develop a synergetic regional PM_(2.5)and O_(3)control strategy.This study develops an emission-to-concentration response surface model and proposes a synergetic pathway for PM_(2.5)and O_(3)control in the Yangtze River Delta(YRD)based on the framework of the Air Benefit and Cost and Attainment Assessment System(ABaCAS).Results suggest that the regional emissions of NOx,SO_(2),NH3,VOCs(volatile organic compounds)and primary PM_(2.5)should be reduced by 18%,23%,14%,17%and 33%compared with 2017 to achieve 25%and 5% decreases of PM_(2.5)and O_(3)in 2025,and that the emission reduction ratios will need to be 50%,26%,28%,28% and 55%to attain the National Ambient Air Quality Standard.To effectively reduce the O_(3) pollution in the central and eastern YRD,VOCs controls need to be strengthened to reduce O_(3)by 5%,and then NOx reduction should be accelerated for air quality attainment.Meanwhile,control of primary PM_(2.5)emissions shall be prioritized to address the severe PM_(2.5)pollution in the northern YRD.For most cities in the YRD,the VOCs emission reduction ratio should be higher than that for NOx in Spring and Autumn.NOx control should be increased in summer rather than winter when a strong VOC-limited regime occurs.Besides,regarding the emission control of industrial processes,on-road vehicle and residential sources shall be prioritized and the joint control area should be enlarged to include Shandong,Jiangxi and Hubei Province for effective O_(3)control.
基金supported by the National Natural Science Foundation of China(No.42175135)the Science and Technology Commission of the Shanghai Municipality(No.20ZR1447800).
文摘Monocyclic aromatic hydrocarbons(MAHs)and polycyclic aromatic hydrocarbons(PAHs)are both well known as hazardous air pollutants and also important anthropogenic precursors of tropospheric ozone(O3)and secondary organic aerosols(SOA).In recent years,there have been intensive studies covering MAHs emission from various sources and their behavior under stimulated photochemical conditions.Yet in-situ measurements of PAHs presence and variations in ambient air are sparse.Herein we conducted large geometrical scale mobile measurements for 16 aromatic hydrocarbons(AHs,including 7 MAHs and 9 PAHs)in eastern China between October 27 and November 8,2019.This unique dataset has allowed for some insights in terms of AHs concentration variations,accompanying chemical composition,source contributions and spatial distributions in eastern China.In general,AHs showed a clear concentration variability between the south and the north of the Yangtze River Delta(YRD).The concentrations of PAHs were approximately 9%of AHs,but contributed 23%of SOA formation potential.Source apportionment via positive matrix factorization(PMF)model revealed that industrial processes as the largest source(44%)of observed AHs,followed by solvent usage(21%),vehicle exhaust(19%),coal combustion(11%)and coking processes(6%).In the perspective of PAHs sources,coal combustion emissions were identified as the dominating factor of a share of 41%–52%in eastern China.Our findings complemented the simultaneously monitoring information of PAHs and MAHs in eastern China,revealed the importance of PAHs to SOA formation and highlighted the necessity of formulating strategies to reduce emissions from anthropogenic sources and reduce risks to human health.
基金supported by National Natural Science Foundation of China(No.21771061)the Outstanding Youth Fund of Heilongjiang Province(No.JQ 2020B002)+1 种基金the Natural Science Foundation of Heilongjiang Province(No.UNPYSCT2020006)Natural Science Foundation of Jiangxi Province(No.20202BABL213002)。
文摘Fabricating an efficient charge transfer pathway at the compact interface between two kinds of semiconductors is an important strategy for designing hydrogen production heterojunction photocatalysts.In this work,we prepared a compact,stable and oxygen vacancy-rich photocatalyst(SnO_(2)/TiO_(2) heterostructure)via a simple and reasonable in-situ synthesis method.Briefly,SnCl_(2)–2H_(2)O is hydrolyzed on the TiO_(2) precursor.After the pyrolysis process,SnO_(2) nanoparticles(5 nm)were dispersed on the surface of ultrathin TiO_(2) nanosheets uniformly.Herein,the heterojunction system can offer abundant oxygen vacancies,which can act as active sites for catalytic reactions.Meanwhile,the interfacial contact of SnO_(2)/TiO_(2) grading semiconductor oxide is uniform and tight,which can promote the separation and migration of photogenerated carriers.As shown in the experimental results,the hydrogen production rate of SnO_(2)/TiO_(2) is 16.7 mmol h^(-1)g^(-1)(4.4 times higher than that of TiO_(2)),which is owing to its good dynamical properties.This work demonstrates an efficient strategy of tight combining SnO_(2)/TiO_(2) with abundant oxygen vacancies to improve catalytic efficiency.
基金supported by the National Natural Science Foundation of China(No.42022050)Guangdong Foundation for Program of Science and Technology Research(Nos.2019B121205006 and 2020B1212060053)+1 种基金the Guangdong Science and Technology Department(No.2017GC010501)CAS Pioneer Hundred Talents program.
文摘Heterogeneous reaction of NO_(2) with mineral dust aerosol may play important roles in troposphere chemistry,and has been investigated by a number of laboratory studies.However,the influence of mineralogy on this reaction has not been well understood,and its impact on aerosol hygroscopicity is not yet clear.This work investigated heterogeneous reactions of NO_(2)(∼10 ppmv)with K-feldspar,illite,kaolinite,montmorillonite and Arizona Test Dust(ATD)at room temperature as a function of relative humidity(<1%to 80%)and reaction time(up to 24 hr).Heterogeneous reactivity towards NO_(2) was low for illite,kaolinite,montmorillonite and ATD,and uptake coefficients of NO_(2),γ(NO_(2)),were determined to be around or smaller than 1×10^(−8);K-feldspar exhibited higher reactivity towards NO_(2),and CaCO_(3) is most reactive among the nine mineral dust samples considered in this and previous work.After heterogeneous reaction with NO_(2) for 24 hr,increase in hygroscopicity was nearly insignificant for illite,kaolinite and montmorillonite,and small but significant for K-feldspar;in addition,large increase in hygroscopicity was observed for ATD,although the increase in hygroscopicity was still smaller than CaCO_(3).