The appropriate reference gene is a prerequisite for accurate normalization of gene expression level,and research on suitable reference genes in clam Cyclina sinensis is scarce.To improve the situation,we selected fiv...The appropriate reference gene is a prerequisite for accurate normalization of gene expression level,and research on suitable reference genes in clam Cyclina sinensis is scarce.To improve the situation,we selected five commonly used housekeeping genes,including β-actin,Elongation factor 1-α(EF1-α),Glyceraldehyde-3-pho sphate dehydrogenase(GAPDH),40S ribosomal protein S18(RPS18),and Tubulin a(TUB-α),then evaluated their expression stability in different adult tissues and under different experimental treatments(salinity stress and Vibrio parahaemolyticus infection).Their expression stability was analyzed by three frequently used programs,geNorm,NormFinder,and BestKeeper.This analysis indicated that multiple genes should be used for normalization,and we concluded that the reference gene combination GAPDH-RPS18-β-actin,should be used for qRT-PCR analysis in different tissues of C.sinensis under normal physiological conditions.For the clams under salinity stress and Vibrio infection,EF1-α-GAPDHRPS18 was recommended as the gene combination for qRT-PCR normalization.TUB-αwas generally poorly ranked by all programs,and should not be used in future studies.This study should provide fundamental support for accurate quantitative gene expression analysis of this species.展开更多
In this study,we investigated the preferable explant types and sterilization method for tissue culture in Chinese chestnut,in order to provide a technical support for the asexual reproduction of Chinese chestnut.The b...In this study,we investigated the preferable explant types and sterilization method for tissue culture in Chinese chestnut,in order to provide a technical support for the asexual reproduction of Chinese chestnut.The base,middle and apex parts of annual shoots with buds in Chinese chestnut were sampled and cut to 2-3 cm stem segments each with one bud,then sterilized orderly with different duration in 2%NaClO plus 0.1%HgCl_(2)solutions.The results indicated that the duration of 2%NaClO for 20 min+0.1%HgCl_(2)for 15 min exerted an effective disinfection property on the middle parts of annual shoots with buds,and achieved a contamination rate under 5%and a survival rate over 90%.展开更多
In this paper,we summed up the research advance in fertilization techniques of Chinese chestnut(Castanea mollissima Blume.),discussed the difference of fertilizer characteristics,fertilizer types,fertilization period,...In this paper,we summed up the research advance in fertilization techniques of Chinese chestnut(Castanea mollissima Blume.),discussed the difference of fertilizer characteristics,fertilizer types,fertilization period,fertilization methods and research progress of formula fertilization in chestnut orchard,and finally prospected the future research of agricultural technical measure of chestnut fertilization work.展开更多
Fine particles associated with haze pollution threaten the health of more than 400 million people in China. It is therefore of great importance to thoroughly investigate and understand their composition. To determine ...Fine particles associated with haze pollution threaten the health of more than 400 million people in China. It is therefore of great importance to thoroughly investigate and understand their composition. To determine the physicochemical properties in atmospheric fine particles at the micrometer level, we described a sensitive and feasible surface-enhanced Raman scattering(SERS) method using Ag foil as a substrate. This novel method enhanced the Raman signal intensities up to 10,000 a.u. for ν(NO_3^-) in fine particles.The SERS effect of Ag foil was further studied experimentally and theoretically and found to have an enhancement factor of the order of ～10~4. Size-fractionated real particle samples with aerodynamic diameters of 0.4–2.5 μm were successfully collected on a heavy haze day,allowing ready observation of morphology and identification of chemical components, such as soot, nitrates, and sulfates. These results suggest that the Ag-foil-based SERS technique can be effectively used to determine the microscopic characteristics of individual fine particles, which will help to understand haze formation mechanisms and formulate governance policies.展开更多
The nondestructive characterization of the mixing state of individual fine particles using the traditional single particle analysis technique remains a challenge.In this study,fine particles were collected during haze...The nondestructive characterization of the mixing state of individual fine particles using the traditional single particle analysis technique remains a challenge.In this study,fine particles were collected during haze events under different pollution levels from September 5 to 112017 in Beijing,China.A nondestructive surface-enhanced Raman scattering(SERS)technique was employed to investigate the morphology,chemical composition,and mixing state of the multiple components in the individual fine particles.Optical image and SERS spectral analysis results show that soot existing in the form of opaque material was predominant during clear periods(PM_(2.5)≤75μg/m^(3)).During polluted periods(PM_(2.5)>75μg/m^(3)),opaque particles mixed with transparent particles(nitrates and sulfates)were generally observed.Direct classical least squares analysis further identified the relative abundances of the three major components of the single particles:soot(69.18%),nitrates(28.71%),and sulfates(2.11%).A negative correlation was observed between the abundance of soot and the mass concentration of PM_(2.5).Furthermore,mapping analysis revealed that on hazy days,PM_(2.5)existed as a core-shell structure with soot surrounded by nitrates and sulfates.This mixing state analysis method for individual PM_(2.5)particles provides information regarding chemical composition and haze formation mechanisms,and has the potential to facilitate the formulation of haze prevention and control policies.展开更多
Combination therapy is one of the potential strategies for tackling complicated tumor treatments like drug resistance.In this work,we have generated a therapeutic cisplatin-crosslinked albumin hydrogel(BC-Gel)that all...Combination therapy is one of the potential strategies for tackling complicated tumor treatments like drug resistance.In this work,we have generated a therapeutic cisplatin-crosslinked albumin hydrogel(BC-Gel)that allows the local release of L-Buthionine-sulfoximine(BSO),cisplatin,and glucose oxidase(GOx)with distinct release kinetics.The BC-Gel with favorable biostimuli degradability and injectability could release therapeutic agents in a programmed manner within the tumor microenvironment(TME).The preferentially released BSO significantly suppressed the glutathione(GSH)-related cisplatin resistance and sensitized the tumor cells to cisplatin by inhibiting theγ-glutamylcysteine synthetase.Meanwhile,cisplatin achieved a sequential release and long-term treatment following the bioresponsive gel degradation under the combined action of chloride ions(Cl−)and proteinase in the body.In addition,the overproduced H_(2)O_(2)of GOx-catalyzed glucose oxidation accelerated the depletion of existed GSH within cells and further weakened the cisplatin resistance,achieving enhanced tumor treatment together with a strong cell-killing effect.The above sequential drug release strategy based on the dual GSH depletion effect breaks the balance of the GSH-mediated redox TME and enhances the sensitivity of A549 cells to cisplatin forcefully,and provides a promising way for temporal control of drug release as well as efficient cancer combination therapy.展开更多
Titanium and its alloys are often used as substrates for dental implants due to their excellent mechanical properties and good biocompatibility.However,their ability to bind to neighboring bone is limited due to the l...Titanium and its alloys are often used as substrates for dental implants due to their excellent mechanical properties and good biocompatibility.However,their ability to bind to neighboring bone is limited due to the lack of biological activity.At the same time,they show poor antibacterial ability which can easily cause bacterial infection and chronic inflammation,eventually resulting in implant failure.The preparation of composite hydroxyapatite coatings with antibacterial ability can effectively figure out these concerns.In this review,the research status and development trends of antibacterial hydroxyapatite coatings constructed on titanium and its alloys are analyzed and reviewed.This review may provide valuable reference for the preparation and application of high-performance and multi-functional dental implant coatings in the future.展开更多
Insights from the adverse effect of humic acid （HA） on arsenate removal with hydrous ferric oxide （HFO） coprecipitation can further our understanding of the fate of As（V） in water treatment process. The motivati...Insights from the adverse effect of humic acid （HA） on arsenate removal with hydrous ferric oxide （HFO） coprecipitation can further our understanding of the fate of As（V） in water treatment process. The motivation of our study is to explore the competitive adsorption mechanisms of humic acid and As（V） on HFO on the molecular scale. Multiple complementary techniques were used including macroscopic adsorption experiments, surface enhanced Raman scattering （SERS）, extended X-ray absorption fine structure （EXAFS） spectroscopy, flow-cell attenuated total reflectance Fourier transform infrared （ATR-FTIR） measurement, and charge distribution multisite complexation （CD- MUSIC） modeling. The As（V） removal efficiency was reduced from over 95% to about 10% with the increasing HA concentration to 25 times of As（V） mass concentration. The SERS analysis excluded the HA-As（V） complex formation. The EXAFS results indicate that As（V） formed bidentate binuclear surface complexes in the presence of HA as evidenced by an As-Fe distance of 3.26--3.31 ,~. The in situ ATR-FTIR measurements show that As（V） replaces surface hydroxyl groups and forms inner- sphere complex. High concentrations of HA may physically block the surface sites and inhibit the As（V） access. The adsorption of As（V） and HA decreased the point of zero charge of HFO from 7.8 to 5.8 and 6.3, respectively. The CD-MUSIC model described the zeta potential curves and adsorption edges of As（V） and HA reasonably well.展开更多
Since their initial clinical implementation,antibiotics have become one of the foundations of modern medicine.Antibiotics used in humans and animals are excreted through urine and feces[1],which enter the surface wate...Since their initial clinical implementation,antibiotics have become one of the foundations of modern medicine.Antibiotics used in humans and animals are excreted through urine and feces[1],which enter the surface water or groundwater,where they eventually contaminate the water supply system.Trace levels of antibiotics,usually at nanogram per liter,have been reported in both tap and bottled water[2,3]and these compounds are often difficult to be completely removed,even after the advanced purification provided by high-end laboratory systems[4].Thus experimental reagents and materials might be contaminated when produced using water with trace antibiotic contamination.展开更多
To understand the further impacts of multiple stressors in freshwater, we investigated the effects of heavy metal （HM, Cu and Zn） and nutrient enrichments （nitrogen and phosphorus, NP） on microbial decomposition o...To understand the further impacts of multiple stressors in freshwater, we investigated the effects of heavy metal （HM, Cu and Zn） and nutrient enrichments （nitrogen and phosphorus, NP） on microbial decomposition of Pterocarya stenoptera litter and the associated extracellular enzyme activities and microbial biomass with microcosms. Results showed that the decomposition rates were slower in the polluted stream waters than those in the unpolluted ones, which corresponded to lower microbial biomass and integrated enzyme activities of cellulose and ^-glucosidase. The decomposition rates were accelerated at low HM level, which was associated with the stimulated enzyme activities of hydrolytic enzymes or was stimulated by both NP levels in polluted stream waters. In particular, the hydrolase enzyme activities of microbial communities in polluted stream waters were stimulated by low HM level, suggesting that low HM level-stimulated litter decomposition may be due to the increased enzymatic activities. When microbial communities were exposed to HM and NP simultaneously, the inhibitory effect （in unpolluted stream waters） or the stimulated effect （in polluted stream waters） of low HM concentration was enhanced and attenuated, respectively, which suggests that the NP antagonistic effect against HM toxicity on litter decomposition may contribute to the litter- associated extracellular enzyme activities. These results suggest that the may have antagonistic effects on stream ecosystem functioning. of HM and NP展开更多
Concerns over exposure to mercury have motivated the exploration of cost-effective,rapid,and reliable method for monitoring Hg^2＋ in the environment.Recently,surface-enhanced Raman scattering（SERS） has become a pro...Concerns over exposure to mercury have motivated the exploration of cost-effective,rapid,and reliable method for monitoring Hg^2＋ in the environment.Recently,surface-enhanced Raman scattering（SERS） has become a promising alternative method for Hg^2＋ analysis.SERS is a spectroscopic technique which combines modern laser spectroscopy with the optical properties of nano-sized noble metal structures,resulting in substantially increased Raman signals.When Hg^2＋ is in a close contact with metallic nanostructures,the SERS effect provides unique structural information together with ultrasensitive detection limits.This review introduces the principles and contemporary approaches of SERS-based Hg^2＋detection.In addition,the perspective and challenges are briefly discussed.展开更多
High tech organizations confront dual demands of exploration and exploitation,particularly in today’s competitive environment marked by a trend of volatility,uncertainty,complexity,and ambiguity.Although there is gen...High tech organizations confront dual demands of exploration and exploitation,particularly in today’s competitive environment marked by a trend of volatility,uncertainty,complexity,and ambiguity.Although there is general consensus about the relationship between ambidexterity and firm performance,few studies have probed into the mechanism of how it is applied in the strategic management process.Considering the premise of environmental change,this research considers a multilevel perspective on the nature of organizational ambidexterity and its functioning in the whole strategic management process.Through a comparative case study of the two most famous high tech companies in China,a model is provided to reflect the functioning of organizational ambidexterity where a cognitive pattern of top management teamsplays a critical role in the ability that the organizations demonstrate.This research also contributes to the literature of entrepreneurship by extending innovation from a demand-side perspective,where the core of product/market exploration/exploitation activities could be expanded into customer value creation.Undertaking a careful analysis of the mechanism of organizational ambidexterity,this research sheds new light on the literature of strategic management that operates in a more turbulent environment.展开更多
The problem of subgraph matching is one fundamental issue in graph search,which is NP-Complete problem.Recently,subgraph matching has become a popular research topic in the field of knowledge graph analysis,which has ...The problem of subgraph matching is one fundamental issue in graph search,which is NP-Complete problem.Recently,subgraph matching has become a popular research topic in the field of knowledge graph analysis,which has a wide range of applications including question answering and semantic search.In this paper,we study the problem of subgraph matching on knowledge graph.Specifically,given a query graph q and a data graph G,the problem of subgraph matching is to conduct all possible subgraph isomorphic mappings of q on G.Knowledge graph is formed as a directed labeled multi-graph having multiple edges between a pair of vertices and it has more dense semantic and structural features than general graph.To accelerate subgraph matching on knowledge graph,we propose a novel subgraph matching algorithm based on subgraph index for knowledge graph,called as FGqT-Match.The subgraph matching algorithm consists of two key designs.One design is a subgraph index of matching-driven flow graph(FGqT),which reduces redundant calculations in advance.Another design is a multi-label weight matrix,which evaluates a near-optimal matching tree for minimizing the intermediate candidates.With the aid of these two key designs,all subgraph isomorphic mappings are quickly conducted only by traversing FGqj.Extensive empirical studies on real and synthetic graphs demonstrate that our techniques outperform the state-of-the-art algorithms.展开更多
Fine particles associated with haze pollution threaten the health of over 400 million people in China. Owing to excellent non-destructive fingerprint recognition characteristics, Raman and surface-enhanced Raman scatt...Fine particles associated with haze pollution threaten the health of over 400 million people in China. Owing to excellent non-destructive fingerprint recognition characteristics, Raman and surface-enhanced Raman scattering(SERS) are often used to analyze the composition of fine particles to determine their physical and chemical properties as well as reaction mechanisms. However, there is no comprehensive Raman spectral library of fine particles. Furthermore, various studies that used SERS for fine-particle composition analysis showed that the uniqueness of the SERS substrates and different excitation wavelengths can produce a different spectrum for the same fine-particle component. To overcome this limitation, we conducted SERS experiments with a portable Raman spectrometer using two common SERS substrates(silver(Ag) foil and gold nanoparticles(Au NPs)) and a 785 nm laser. Herein, we introduced three main particle component types(sulfate-nitrate-ammonium(SNA), organic material, and soot) with a total of 39 chemical substances. We scanned the solid Raman, liquid Raman, and SERS spectra of these substances and constructed a fine-particle reference library containing 105 spectra. Spectral results indicated that for soot and SNA, the differences in characteristic peaks mainly originated from the solid-liquid phase transition;Ag foil had little effect on this difference, while the Au NPs caused a significant red shift in the peak positions of polycyclic aromatic hydrocarbons. Moreover, with various characteristic peak positions in the three types of spectra, we could quickly and correctly distinguish substances. We hope that this spectral library will aid in the future identification of fine particles.展开更多
基金Supported by the funding for school-level research projects of Yancheng Institute of Technology(No.xjr2019047)the National Natural Science Foundation of China(No.31902362)。
文摘The appropriate reference gene is a prerequisite for accurate normalization of gene expression level,and research on suitable reference genes in clam Cyclina sinensis is scarce.To improve the situation,we selected five commonly used housekeeping genes,including β-actin,Elongation factor 1-α(EF1-α),Glyceraldehyde-3-pho sphate dehydrogenase(GAPDH),40S ribosomal protein S18(RPS18),and Tubulin a(TUB-α),then evaluated their expression stability in different adult tissues and under different experimental treatments(salinity stress and Vibrio parahaemolyticus infection).Their expression stability was analyzed by three frequently used programs,geNorm,NormFinder,and BestKeeper.This analysis indicated that multiple genes should be used for normalization,and we concluded that the reference gene combination GAPDH-RPS18-β-actin,should be used for qRT-PCR analysis in different tissues of C.sinensis under normal physiological conditions.For the clams under salinity stress and Vibrio infection,EF1-α-GAPDHRPS18 was recommended as the gene combination for qRT-PCR normalization.TUB-αwas generally poorly ranked by all programs,and should not be used in future studies.This study should provide fundamental support for accurate quantitative gene expression analysis of this species.
基金Supported by The Sub-project of Hebei Collaborative Innovation Center of Chestnut Industry(202202)The Sub-project of Research and Development Center of Horticultural Crop Breeding Application Technology of Hebei University(YF201404)+1 种基金Chestnut Science and Technology Backyard of Hebei QinglongChina Rural Special Technology Association。
文摘In this study,we investigated the preferable explant types and sterilization method for tissue culture in Chinese chestnut,in order to provide a technical support for the asexual reproduction of Chinese chestnut.The base,middle and apex parts of annual shoots with buds in Chinese chestnut were sampled and cut to 2-3 cm stem segments each with one bud,then sterilized orderly with different duration in 2%NaClO plus 0.1%HgCl_(2)solutions.The results indicated that the duration of 2%NaClO for 20 min+0.1%HgCl_(2)for 15 min exerted an effective disinfection property on the middle parts of annual shoots with buds,and achieved a contamination rate under 5%and a survival rate over 90%.
基金Supported by Key R&D Program of Hebei Province(21326304D)Hebei Provincial Innovation Capacity Improvement Project(20567657H).
文摘In this paper,we summed up the research advance in fertilization techniques of Chinese chestnut(Castanea mollissima Blume.),discussed the difference of fertilizer characteristics,fertilizer types,fertilization period,fertilization methods and research progress of formula fertilization in chestnut orchard,and finally prospected the future research of agricultural technical measure of chestnut fertilization work.
基金supported by the National Natural Science Foundation of China (Nos.21707077,81571130090)the National Key Research and Development Program (Nos.2017YFC0211500,2016YFC0202700,2017YFC0211601)+1 种基金the Science Fund for Creative Research Groups (No.21521064)the China Postdoctoral Science Foundation (No.2017M610923)
文摘Fine particles associated with haze pollution threaten the health of more than 400 million people in China. It is therefore of great importance to thoroughly investigate and understand their composition. To determine the physicochemical properties in atmospheric fine particles at the micrometer level, we described a sensitive and feasible surface-enhanced Raman scattering(SERS) method using Ag foil as a substrate. This novel method enhanced the Raman signal intensities up to 10,000 a.u. for ν(NO_3^-) in fine particles.The SERS effect of Ag foil was further studied experimentally and theoretically and found to have an enhancement factor of the order of ～10~4. Size-fractionated real particle samples with aerodynamic diameters of 0.4–2.5 μm were successfully collected on a heavy haze day,allowing ready observation of morphology and identification of chemical components, such as soot, nitrates, and sulfates. These results suggest that the Ag-foil-based SERS technique can be effectively used to determine the microscopic characteristics of individual fine particles, which will help to understand haze formation mechanisms and formulate governance policies.
基金supported by the National Natural Science Foundation of China(Nos.21707077,21775042)the National Key Research and Development Program of China(No.2017YFA0207003)the Fundamental Research Funds for the Central Universities(No.2020 MS037)。
文摘The nondestructive characterization of the mixing state of individual fine particles using the traditional single particle analysis technique remains a challenge.In this study,fine particles were collected during haze events under different pollution levels from September 5 to 112017 in Beijing,China.A nondestructive surface-enhanced Raman scattering(SERS)technique was employed to investigate the morphology,chemical composition,and mixing state of the multiple components in the individual fine particles.Optical image and SERS spectral analysis results show that soot existing in the form of opaque material was predominant during clear periods(PM_(2.5)≤75μg/m^(3)).During polluted periods(PM_(2.5)>75μg/m^(3)),opaque particles mixed with transparent particles(nitrates and sulfates)were generally observed.Direct classical least squares analysis further identified the relative abundances of the three major components of the single particles:soot(69.18%),nitrates(28.71%),and sulfates(2.11%).A negative correlation was observed between the abundance of soot and the mass concentration of PM_(2.5).Furthermore,mapping analysis revealed that on hazy days,PM_(2.5)existed as a core-shell structure with soot surrounded by nitrates and sulfates.This mixing state analysis method for individual PM_(2.5)particles provides information regarding chemical composition and haze formation mechanisms,and has the potential to facilitate the formulation of haze prevention and control policies.
基金supported by the National Natural Science Foundation of China(Nos.22075065,22161142015,and 22001054)the National Key R&D Program of China(Nos.2020YFA0908500 and 2018YFA0901600)the Research Startup Fund from Hangzhou Normal University(Nos.2019QDL025,2019QDL026,and 4095C5022121604).
文摘Combination therapy is one of the potential strategies for tackling complicated tumor treatments like drug resistance.In this work,we have generated a therapeutic cisplatin-crosslinked albumin hydrogel(BC-Gel)that allows the local release of L-Buthionine-sulfoximine(BSO),cisplatin,and glucose oxidase(GOx)with distinct release kinetics.The BC-Gel with favorable biostimuli degradability and injectability could release therapeutic agents in a programmed manner within the tumor microenvironment(TME).The preferentially released BSO significantly suppressed the glutathione(GSH)-related cisplatin resistance and sensitized the tumor cells to cisplatin by inhibiting theγ-glutamylcysteine synthetase.Meanwhile,cisplatin achieved a sequential release and long-term treatment following the bioresponsive gel degradation under the combined action of chloride ions(Cl−)and proteinase in the body.In addition,the overproduced H_(2)O_(2)of GOx-catalyzed glucose oxidation accelerated the depletion of existed GSH within cells and further weakened the cisplatin resistance,achieving enhanced tumor treatment together with a strong cell-killing effect.The above sequential drug release strategy based on the dual GSH depletion effect breaks the balance of the GSH-mediated redox TME and enhances the sensitivity of A549 cells to cisplatin forcefully,and provides a promising way for temporal control of drug release as well as efficient cancer combination therapy.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.12272253,11632013,and 11902214)the Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(Grant Nos.2021SX-AT008 and 2021SX-AT009)The support of the Fund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province(Grant No.20220006)is also acknowledged with gratitude.
文摘Titanium and its alloys are often used as substrates for dental implants due to their excellent mechanical properties and good biocompatibility.However,their ability to bind to neighboring bone is limited due to the lack of biological activity.At the same time,they show poor antibacterial ability which can easily cause bacterial infection and chronic inflammation,eventually resulting in implant failure.The preparation of composite hydroxyapatite coatings with antibacterial ability can effectively figure out these concerns.In this review,the research status and development trends of antibacterial hydroxyapatite coatings constructed on titanium and its alloys are analyzed and reviewed.This review may provide valuable reference for the preparation and application of high-performance and multi-functional dental implant coatings in the future.
基金supported by the National Natural Science Foundation of China (No. 41373123, 41023005, 21321004)Research Center for EcoEnvironmental Sciences, Chinese Academy of Sciences (No. YSW2013A01)
文摘Insights from the adverse effect of humic acid （HA） on arsenate removal with hydrous ferric oxide （HFO） coprecipitation can further our understanding of the fate of As（V） in water treatment process. The motivation of our study is to explore the competitive adsorption mechanisms of humic acid and As（V） on HFO on the molecular scale. Multiple complementary techniques were used including macroscopic adsorption experiments, surface enhanced Raman scattering （SERS）, extended X-ray absorption fine structure （EXAFS） spectroscopy, flow-cell attenuated total reflectance Fourier transform infrared （ATR-FTIR） measurement, and charge distribution multisite complexation （CD- MUSIC） modeling. The As（V） removal efficiency was reduced from over 95% to about 10% with the increasing HA concentration to 25 times of As（V） mass concentration. The SERS analysis excluded the HA-As（V） complex formation. The EXAFS results indicate that As（V） formed bidentate binuclear surface complexes in the presence of HA as evidenced by an As-Fe distance of 3.26--3.31 ,~. The in situ ATR-FTIR measurements show that As（V） replaces surface hydroxyl groups and forms inner- sphere complex. High concentrations of HA may physically block the surface sites and inhibit the As（V） access. The adsorption of As（V） and HA decreased the point of zero charge of HFO from 7.8 to 5.8 and 6.3, respectively. The CD-MUSIC model described the zeta potential curves and adsorption edges of As（V） and HA reasonably well.
基金supported by the National Natural Science Foundation of China(32072916)。
文摘Since their initial clinical implementation,antibiotics have become one of the foundations of modern medicine.Antibiotics used in humans and animals are excreted through urine and feces[1],which enter the surface water or groundwater,where they eventually contaminate the water supply system.Trace levels of antibiotics,usually at nanogram per liter,have been reported in both tap and bottled water[2,3]and these compounds are often difficult to be completely removed,even after the advanced purification provided by high-end laboratory systems[4].Thus experimental reagents and materials might be contaminated when produced using water with trace antibiotic contamination.
基金supported by the Major Science and Technology Program for Water Pollution Control and Treatment(No.2012ZX07204-004-003)the Ph.D Programs Foundation of Ministry of Education of China(No.20110091110018)+1 种基金the "Strategic Priority Research Program-Climate Change:Carbon Budget and Related Issues" of the Chinese Academy of Sciences(No.XDA05050204)the National Science and Technology Infrastructure Platforms from Ministry of Science and Technology(No.2005DKA21403-JK)
文摘To understand the further impacts of multiple stressors in freshwater, we investigated the effects of heavy metal （HM, Cu and Zn） and nutrient enrichments （nitrogen and phosphorus, NP） on microbial decomposition of Pterocarya stenoptera litter and the associated extracellular enzyme activities and microbial biomass with microcosms. Results showed that the decomposition rates were slower in the polluted stream waters than those in the unpolluted ones, which corresponded to lower microbial biomass and integrated enzyme activities of cellulose and ^-glucosidase. The decomposition rates were accelerated at low HM level, which was associated with the stimulated enzyme activities of hydrolytic enzymes or was stimulated by both NP levels in polluted stream waters. In particular, the hydrolase enzyme activities of microbial communities in polluted stream waters were stimulated by low HM level, suggesting that low HM level-stimulated litter decomposition may be due to the increased enzymatic activities. When microbial communities were exposed to HM and NP simultaneously, the inhibitory effect （in unpolluted stream waters） or the stimulated effect （in polluted stream waters） of low HM concentration was enhanced and attenuated, respectively, which suggests that the NP antagonistic effect against HM toxicity on litter decomposition may contribute to the litter- associated extracellular enzyme activities. These results suggest that the may have antagonistic effects on stream ecosystem functioning. of HM and NP
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDB14020201)the National Natural Science Foundation of China (Nos. 21337004, 21321004)
文摘Concerns over exposure to mercury have motivated the exploration of cost-effective,rapid,and reliable method for monitoring Hg^2＋ in the environment.Recently,surface-enhanced Raman scattering（SERS） has become a promising alternative method for Hg^2＋ analysis.SERS is a spectroscopic technique which combines modern laser spectroscopy with the optical properties of nano-sized noble metal structures,resulting in substantially increased Raman signals.When Hg^2＋ is in a close contact with metallic nanostructures,the SERS effect provides unique structural information together with ultrasensitive detection limits.This review introduces the principles and contemporary approaches of SERS-based Hg^2＋detection.In addition,the perspective and challenges are briefly discussed.
文摘High tech organizations confront dual demands of exploration and exploitation,particularly in today’s competitive environment marked by a trend of volatility,uncertainty,complexity,and ambiguity.Although there is general consensus about the relationship between ambidexterity and firm performance,few studies have probed into the mechanism of how it is applied in the strategic management process.Considering the premise of environmental change,this research considers a multilevel perspective on the nature of organizational ambidexterity and its functioning in the whole strategic management process.Through a comparative case study of the two most famous high tech companies in China,a model is provided to reflect the functioning of organizational ambidexterity where a cognitive pattern of top management teamsplays a critical role in the ability that the organizations demonstrate.This research also contributes to the literature of entrepreneurship by extending innovation from a demand-side perspective,where the core of product/market exploration/exploitation activities could be expanded into customer value creation.Undertaking a careful analysis of the mechanism of organizational ambidexterity,this research sheds new light on the literature of strategic management that operates in a more turbulent environment.
基金the National Natural Science Foundation of China(Grant Nos.61976032,62002039).
文摘The problem of subgraph matching is one fundamental issue in graph search,which is NP-Complete problem.Recently,subgraph matching has become a popular research topic in the field of knowledge graph analysis,which has a wide range of applications including question answering and semantic search.In this paper,we study the problem of subgraph matching on knowledge graph.Specifically,given a query graph q and a data graph G,the problem of subgraph matching is to conduct all possible subgraph isomorphic mappings of q on G.Knowledge graph is formed as a directed labeled multi-graph having multiple edges between a pair of vertices and it has more dense semantic and structural features than general graph.To accelerate subgraph matching on knowledge graph,we propose a novel subgraph matching algorithm based on subgraph index for knowledge graph,called as FGqT-Match.The subgraph matching algorithm consists of two key designs.One design is a subgraph index of matching-driven flow graph(FGqT),which reduces redundant calculations in advance.Another design is a multi-label weight matrix,which evaluates a near-optimal matching tree for minimizing the intermediate candidates.With the aid of these two key designs,all subgraph isomorphic mappings are quickly conducted only by traversing FGqj.Extensive empirical studies on real and synthetic graphs demonstrate that our techniques outperform the state-of-the-art algorithms.
基金supported by National Natural Science Foundation of China (Nos. 21707077, 21775042, and 21475134)the National Key Research and Development Program of China (No. 2017YFA0207003)+1 种基金the Special Fund of Beijing Key Laboratory of Indoor Air Quality Evaluation and Control (No. BZ0344KF2006)the Fundamental Research Funds for the Central Universities (No. 2020MS037)。
文摘Fine particles associated with haze pollution threaten the health of over 400 million people in China. Owing to excellent non-destructive fingerprint recognition characteristics, Raman and surface-enhanced Raman scattering(SERS) are often used to analyze the composition of fine particles to determine their physical and chemical properties as well as reaction mechanisms. However, there is no comprehensive Raman spectral library of fine particles. Furthermore, various studies that used SERS for fine-particle composition analysis showed that the uniqueness of the SERS substrates and different excitation wavelengths can produce a different spectrum for the same fine-particle component. To overcome this limitation, we conducted SERS experiments with a portable Raman spectrometer using two common SERS substrates(silver(Ag) foil and gold nanoparticles(Au NPs)) and a 785 nm laser. Herein, we introduced three main particle component types(sulfate-nitrate-ammonium(SNA), organic material, and soot) with a total of 39 chemical substances. We scanned the solid Raman, liquid Raman, and SERS spectra of these substances and constructed a fine-particle reference library containing 105 spectra. Spectral results indicated that for soot and SNA, the differences in characteristic peaks mainly originated from the solid-liquid phase transition;Ag foil had little effect on this difference, while the Au NPs caused a significant red shift in the peak positions of polycyclic aromatic hydrocarbons. Moreover, with various characteristic peak positions in the three types of spectra, we could quickly and correctly distinguish substances. We hope that this spectral library will aid in the future identification of fine particles.
