Pollutant dynamics and bioavailability greatly differ in soil and aquatic systems. Therefore, specific approaches and models are needed to assess the impact of soil contamination to terrestrial ecosystems. Earthworms ...Pollutant dynamics and bioavailability greatly differ in soil and aquatic systems. Therefore, specific approaches and models are needed to assess the impact of soil contamination to terrestrial ecosystems. Earthworms among other soil invertebrates have received more attention because of their ecological importance. They represent a dominant part of the soil biomass and are soil engineers regulating important soil processes, notably fertilization. The release in soils of pollutants known for their persistence and/or their toxicity is a concern. Exposure of terrestrial species to pollutants that may alter genomic function has become an increasing topic of research in the last decade. Indeed, genome disturbances due to genetic and epigenetic mechanisms may impair growth, as well as reproduction and population dynamics in the long term. Despite their importance in gene expres- sion, epigenetic mechanisms are not yet understood in soil invertebrates. Until now, pollutant-induced changes in genome expression in natural biota are still being studied through structural alteration of DNA. The first biomarker relating to genotoxicant exposure in earthworms from multi-contaminated soils reported is DNA adducts measurements. It has been replaced by DNA breakage measured by the Comet assay, now more commonly used. Functional genomic changes are now being explored owing to molecular ＂omic＂ technologies. Approaches, objectives and results are overviewed herein. The focus is on studies dealing with genotoxicity and populational effects established from environmentally-relevant experiments and in situ studies [Current Zoology 60 （2）： 255-272, 2014].展开更多
Diuron is frequently detected in surface- and groundwater under the vineyards, where organic amendments are often used, in Burgundy of France. Undisturbed column experiments were conducted to study the influence of th...Diuron is frequently detected in surface- and groundwater under the vineyards, where organic amendments are often used, in Burgundy of France. Undisturbed column experiments were conducted to study the influence of three composted organic amendments on diuron leaching through columns of two vineyard soils from Vosne-Roman′ee(VR, calcareous Cambisol) and Beaujolais(Bj, sandy Leptosol), France. Bromide(used as non-reactive tracer) and diuron breakthrough curves(BTCs) were analyzed using convectivedispersive equation(CDE), two-region(mobile-immobile, MIM) and two-site models. No influence of the composts was observed on the bromide recovery rates. The CDE model described well the bromide BTCs for all columns of the Bj soil and seven of the VR soil, suggesting a homogeneous water flow. However, for five VR soil columns, the MIM model fitted better, suggesting a partition of the water flow(15%–50% of matrix flow). The texture, the coarse material content and the tillage of the VR soil could explain this heterogeneity. However, for all columns, diuron leaching was greater through the Bj soil(46%–68%) than the VR soil(28%–39%). The compost addition resulted in a contrasting effect on diuron leaching: no difference or a decrease was observed for the VR soil, probably due to an increase of adsorption sites, whereas no difference or an increase was observed for the Bj soil possibly because of interactions and/or competition of diuron with the compost water-extractable organic matter which could facilitate its transport. All the diuron BTCs were best described using the two-site model, suggesting a large proportion of time-dependent sorption sites(30%–50%). The soil type and the nature of the amendments had contrasting influences on diuron transport. Composts with a high water-soluble fraction must be avoided in sandy soils to reduce the risk of groundwater contamination.展开更多
Hexagonal CeO2 and Eu-doped CeO2 nanoparticles were obtained using a facile microwave-hydro thermal method under mild conditions and their application towards manganese redox flow battery component were studied. The s...Hexagonal CeO2 and Eu-doped CeO2 nanoparticles were obtained using a facile microwave-hydro thermal method under mild conditions and their application towards manganese redox flow battery component were studied. The structural properties were studied by X-ray diffraction and indicate that samples present a fluorite structure. Raman spectroscopy shows Eu3＋ ions substitute Ce4＋ and generate oxygen vacancies. Electrochemical properties of pure and Eu-doped CeO2 films deposited at graphite substrates investigated by cyclic voltammetry and galvanostatic charge-discharge indicate that dopant concentration affects the electrochemical properties of CeO2. The increase in the reversibility redox of electrochemical systems observed is attributed to coexistence of Ce4＋/Ce3＋ redox couple confirmed by XPS.Charge-discharge tests display coulombic and voltage efficiency values of above 80% and 90%, respectively. The obtained specific capacity for Ce（0.99）Eu（0.01）O2（372.49 mAh/g） and pure oxide（334.84 mAh/g）indicates that both samples are promising for application in Mn-batteries.展开更多
In Burkina Faso, significant amounts of endosulfan are applied to cotton fields; in addition, urban vegetable agriculture is often characterised by high fertiliser inputs, such as urban solid wastes containing heavy m...In Burkina Faso, significant amounts of endosulfan are applied to cotton fields; in addition, urban vegetable agriculture is often characterised by high fertiliser inputs, such as urban solid wastes containing heavy metals(e.g., Cu and Cd). Thus, the relevance of surrounding cotton and urban vegetable plots with vetiver(Vetiveria zizanioides) hedges to reduce environmental pollution by micropollutants was investigated using a leaching experiment, with outdoor lysimeters filled with two representative agricultural soils of Burkina Faso: Vertisol and Lixisol. After 6 months, little Cu was found in the leachates(< 0.010% of the applied amount) due to its high adsorption coefficient and its tendency to remain at the soil surface. Despite leachate and bromide recoveries being greater in soils planted with vetiver grass than in the bare soils, smaller amounts of endosulfan and Cd were found in the effluents from the planted soils(0.01% to 0.70% of the applied amount) than in those from the bare soils(0.01% to 1.48% of the applied amount), in agreement with their adsorption coefficients. These results may also be explained by a greater degradation of endosulfan in planted soils compared to bare soils and the absorption of Cd by vetiver. Thus, vetiver may decrease the risk of groundwater contamination,especially for Cd and endosulfan, which are more mobile than Cu. In addition, despite the smaller amounts of endosulfan and Cd measured in the Vertisol leachates(0.01% and 0.04% of the applied amount, respectively) compared to the Lixisol leachates, vetiver was more effective in decreasing the leaching of micropollutants if planted on Lixisol rather than on Vertisol. Further field monitoring is necessary to demonstrate the effectiveness of vetiver under the climatic conditions of Burkina Faso.展开更多
In the agricultural regions of Burkina Faso, urban solid waste fertilizers were usually applied. This activity is likely to contaminate the soils and expose populations to serious diseases. This study aims to assess r...In the agricultural regions of Burkina Faso, urban solid waste fertilizers were usually applied. This activity is likely to contaminate the soils and expose populations to serious diseases. This study aims to assess rate of heavy metal (Cd, Cu, Mn, Pb, Zn, Ni, Cr) contamination in both agricultural lixisol and vertisol and to evaluate the removal efficiency of heavy metals using Vetiver grass on different two mixed heavy metal contaminated soils. A pot experiment was conducted to compare the metal accumulation and overall efficiency of metal uptake by different plant parts (roots and shoots) on both tropical soils. After 3 and 6 months growing on laboratory conditions, Vetiver grass plants were harvested and heavy metal concentrations in shoot and root parts determined by Inductively Coupled Plasma - Atomic Emission Spectroscopy. The results indicate that at 3 and 6 moths, the shoot and root concentrations of heavy metals in Vetiver grass harvested in lixisol were higher than vertisol. For different plant parts, all metal concentrations were higher in root than in shoot, except Cu and Pb. At the 3 and 6 months, the BCF values > 1 for Cd, Cu and Zn in both soils showed Vetiver grass as an effective phyto-stabilizer for these metals. However, the TF values > 1 for Cd (lixisol), Mn, Zn Ni and Cr (vertisol) indicated the efficiency of Vetiver for phytoextraction. The results of this study showed that Vetiver is more effective in lixisol</span><span style="font-family:"">,</span><span style="font-family:""> but it can be used for remediation of both studied tropical soils from agricultural region of Burkina Faso. Nevertheless, considering the special limitations of the experimental conditions, further field monitoring is necessary to demonstrate the phytoremediation efficiency of Vetiver in agricultural soils under the climatic conditions of Burkina Faso.展开更多
The Hall-Héroult process is used for alumina reduction by the use of graphite anodes even though it involves a high emission of carbon dioxide (CO2) and several other organic compounds. Proposals have been made a...The Hall-Héroult process is used for alumina reduction by the use of graphite anodes even though it involves a high emission of carbon dioxide (CO2) and several other organic compounds. Proposals have been made aiming at substituting graphite for a single-phase SnO2-based ceramic with low resistivity and chemical resistance to cryolite, which is characterized as an inconsumable anode, reducing pollutant emissions. To this end, a wide range of studies were carried out on SnO2-based ceramics modified with ZnO as a densification aid doped with the promoters of electrical conductivity such as Nb2O5, Al2O3 and Sb2O3 through a mixture of oxides and hybrid sintering in a microwave oven. The pressed pellets were sintered in a microwave oven up to 1050℃ under a constant heating rate of 10℃/min. After sintering, the density was determined by the Archimedes method, the phases were then characterized by X-ray diffraction, the microstructure and chemical composition resulting from the sintered SnO2-based ceramics were also investigated by field emission scanning electron microscopy (FE-SEM) coupled with an energy-dispersive X-ray spectroscopy (EDS) and the electrical properties were determined by the measurements of the electric field x current density. A single-phase ceramic was obtained with a relative density of above 90% and electrical resistivity of 6.1 Ω·cm at room temperature. The ceramics obtained in this study could be a potential candidate as an inconsumable anode to replace the current fused coke used in the reduction of alumina.展开更多
Exploring the natural availability and intrinsic bioactivity of blood-derived proteins opens new avenues for fabricating bioactive and patient-specific solutions for biomedical applications.Despite their several advan...Exploring the natural availability and intrinsic bioactivity of blood-derived proteins opens new avenues for fabricating bioactive and patient-specific solutions for biomedical applications.Despite their several advantages,their use as inks for 3D printing is limited due to suboptimal rheological properties.To address this,we propose a dual-step strategy based on the initial generation of blood protein-based bulk hydrogels encompassing pristine and photo-responsive protein mixtures to allow their mechanical granularization followed by jamming,establishing injectable and printable granular inks.In this study,two globular-based protein matrices-human platelet lysates(PL)and bovine serum albumin(BSA)-were used as granular inks for 3D printing.We hypothesize that nozzle jamming-in contrast to the typically employed centrifugal jamming-would render optimized results for the granular protein inks’processability.Printability was evaluated in filaments,scaffold grids,and convoluted structures.Taking advantage of the previously introduced photocurable moieties,post-printing photocrosslinking was used for the annealing of themicrogels,leading to increased scaffold mechanical stability and robustness.The nozzle jamming methodology imparted the best print performance and reproducibility,where PLMA-based inks outperformed the BSAMA-based.In addition,the microgel granular constructs allowed primary human-derived adipose stem cells to adhere and proliferate,whereas the PLMA-based ink demonstrated higher cell affinity and enhanced biological performance.We further demonstrated that bioinks could be developed from PLMA-based inks,showcasing high viability without compromising 3D printing performance.Overall,this study gives clear insights into the importance of the jamming process as well as the granularization outcome requirements for the obtention of highly reproducible granular inks for 3D printing.展开更多
Aims and Methods We propose a standard protocol at the landscape to continental scale for examining to what extent the range of ecological conditions found in temperate latitudes explains the variations in climber spe...Aims and Methods We propose a standard protocol at the landscape to continental scale for examining to what extent the range of ecological conditions found in temperate latitudes explains the variations in climber species richness and traits.The protocol was tested in forests of the two Americas.The data set included 151 climber species.We selected four categorical traits and grouped these species into six clusters with regard to these traits.Floristic records of American forests were first gathered into alliances,second combined with bioclimatic indices(rainfall,temperature,continentality).We obtained a total of 59 vegetational units in which we calculated values of climber species richness and proportion of clusters.Vegetational units were ultimately gathered into five forest formations(characterized by leaf longevity).Wetlands and uplands were considered separately.Important Findings Our results emphasize clear trends in large-scale patterns of climber distribution,independently of taxonomy.Climber species richness(in particular woody climbers)peaks in moist and warm upland forests with oceanic climates,and where conifers are rare.In flooded areas,climber richness is also very high and peaks in seasonally flooded large floodplains.In ecological conditions of frost,dryness or lack of nutrients,climber species richness,abundance and trait diversity decline,resulting in the dominance of small,twining and deciduous life traits.展开更多
Literature has reported the synthesis of barium calcium titanates by various synthesis methods such as solid state reaction,co-precipitation and polymer precursors.These compounds are usually obtained using calcium ca...Literature has reported the synthesis of barium calcium titanates by various synthesis methods such as solid state reaction,co-precipitation and polymer precursors.These compounds are usually obtained using calcium carbonate(CaCO_(3)),barium carbonate(BaCO3)and titanium oxide as starting materials.This study investigated the effect of different starting reagents on the synthesis of Ba_(0.8)Ca_(0.2)TiO_(3)(BCT)by complex polymerization method(CPM).Two sets of starting precursors were used:titanium citrate,CaCO_(3)and BaCO3,and titanium citrate and Ba1-xCaxCO3 solid solution precursor.Samples were crystallized at a temperature range from 400℃to 700℃for different time.The obtained powders were characterized by X-ray diffraction(XRD),thermogravimetry(TG)and differential thermal analysis(DTA),and Raman and infrared spectroscopy.The infrared spectroscopy indicated that the chelation processes of Ba,Ca,Ti and CA ions are very similar.The results showed that the use of CaCO_(3)and BaCO3 or Ba1-xCaxCO3 solid solution as precursors does not affect the final properties of BCT powders obtained by CPM.展开更多
文摘Pollutant dynamics and bioavailability greatly differ in soil and aquatic systems. Therefore, specific approaches and models are needed to assess the impact of soil contamination to terrestrial ecosystems. Earthworms among other soil invertebrates have received more attention because of their ecological importance. They represent a dominant part of the soil biomass and are soil engineers regulating important soil processes, notably fertilization. The release in soils of pollutants known for their persistence and/or their toxicity is a concern. Exposure of terrestrial species to pollutants that may alter genomic function has become an increasing topic of research in the last decade. Indeed, genome disturbances due to genetic and epigenetic mechanisms may impair growth, as well as reproduction and population dynamics in the long term. Despite their importance in gene expres- sion, epigenetic mechanisms are not yet understood in soil invertebrates. Until now, pollutant-induced changes in genome expression in natural biota are still being studied through structural alteration of DNA. The first biomarker relating to genotoxicant exposure in earthworms from multi-contaminated soils reported is DNA adducts measurements. It has been replaced by DNA breakage measured by the Comet assay, now more commonly used. Functional genomic changes are now being explored owing to molecular ＂omic＂ technologies. Approaches, objectives and results are overviewed herein. The focus is on studies dealing with genotoxicity and populational effects established from environmentally-relevant experiments and in situ studies [Current Zoology 60 （2）： 255-272, 2014].
文摘Diuron is frequently detected in surface- and groundwater under the vineyards, where organic amendments are often used, in Burgundy of France. Undisturbed column experiments were conducted to study the influence of three composted organic amendments on diuron leaching through columns of two vineyard soils from Vosne-Roman′ee(VR, calcareous Cambisol) and Beaujolais(Bj, sandy Leptosol), France. Bromide(used as non-reactive tracer) and diuron breakthrough curves(BTCs) were analyzed using convectivedispersive equation(CDE), two-region(mobile-immobile, MIM) and two-site models. No influence of the composts was observed on the bromide recovery rates. The CDE model described well the bromide BTCs for all columns of the Bj soil and seven of the VR soil, suggesting a homogeneous water flow. However, for five VR soil columns, the MIM model fitted better, suggesting a partition of the water flow(15%–50% of matrix flow). The texture, the coarse material content and the tillage of the VR soil could explain this heterogeneity. However, for all columns, diuron leaching was greater through the Bj soil(46%–68%) than the VR soil(28%–39%). The compost addition resulted in a contrasting effect on diuron leaching: no difference or a decrease was observed for the VR soil, probably due to an increase of adsorption sites, whereas no difference or an increase was observed for the Bj soil possibly because of interactions and/or competition of diuron with the compost water-extractable organic matter which could facilitate its transport. All the diuron BTCs were best described using the two-site model, suggesting a large proportion of time-dependent sorption sites(30%–50%). The soil type and the nature of the amendments had contrasting influences on diuron transport. Composts with a high water-soluble fraction must be avoided in sandy soils to reduce the risk of groundwater contamination.
基金Project supported by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior(Capes)Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq)+2 种基金Fundaao de AmparoàPesquisa do Estado de Minas Gerais(FAPEMIG)Rede Mineira de Química(RQ-MG)Grupo de Materiais Inorgnicos do Tringulo-GMIT Research Group supported by FAPEMIG(APQ-00330-14)
文摘Hexagonal CeO2 and Eu-doped CeO2 nanoparticles were obtained using a facile microwave-hydro thermal method under mild conditions and their application towards manganese redox flow battery component were studied. The structural properties were studied by X-ray diffraction and indicate that samples present a fluorite structure. Raman spectroscopy shows Eu3＋ ions substitute Ce4＋ and generate oxygen vacancies. Electrochemical properties of pure and Eu-doped CeO2 films deposited at graphite substrates investigated by cyclic voltammetry and galvanostatic charge-discharge indicate that dopant concentration affects the electrochemical properties of CeO2. The increase in the reversibility redox of electrochemical systems observed is attributed to coexistence of Ce4＋/Ce3＋ redox couple confirmed by XPS.Charge-discharge tests display coulombic and voltage efficiency values of above 80% and 90%, respectively. The obtained specific capacity for Ce（0.99）Eu（0.01）O2（372.49 mAh/g） and pure oxide（334.84 mAh/g）indicates that both samples are promising for application in Mn-batteries.
基金financially supported in part by a CORUS Ⅱ Projecta Gabonese Government Fellowship
文摘In Burkina Faso, significant amounts of endosulfan are applied to cotton fields; in addition, urban vegetable agriculture is often characterised by high fertiliser inputs, such as urban solid wastes containing heavy metals(e.g., Cu and Cd). Thus, the relevance of surrounding cotton and urban vegetable plots with vetiver(Vetiveria zizanioides) hedges to reduce environmental pollution by micropollutants was investigated using a leaching experiment, with outdoor lysimeters filled with two representative agricultural soils of Burkina Faso: Vertisol and Lixisol. After 6 months, little Cu was found in the leachates(< 0.010% of the applied amount) due to its high adsorption coefficient and its tendency to remain at the soil surface. Despite leachate and bromide recoveries being greater in soils planted with vetiver grass than in the bare soils, smaller amounts of endosulfan and Cd were found in the effluents from the planted soils(0.01% to 0.70% of the applied amount) than in those from the bare soils(0.01% to 1.48% of the applied amount), in agreement with their adsorption coefficients. These results may also be explained by a greater degradation of endosulfan in planted soils compared to bare soils and the absorption of Cd by vetiver. Thus, vetiver may decrease the risk of groundwater contamination,especially for Cd and endosulfan, which are more mobile than Cu. In addition, despite the smaller amounts of endosulfan and Cd measured in the Vertisol leachates(0.01% and 0.04% of the applied amount, respectively) compared to the Lixisol leachates, vetiver was more effective in decreasing the leaching of micropollutants if planted on Lixisol rather than on Vertisol. Further field monitoring is necessary to demonstrate the effectiveness of vetiver under the climatic conditions of Burkina Faso.
文摘In the agricultural regions of Burkina Faso, urban solid waste fertilizers were usually applied. This activity is likely to contaminate the soils and expose populations to serious diseases. This study aims to assess rate of heavy metal (Cd, Cu, Mn, Pb, Zn, Ni, Cr) contamination in both agricultural lixisol and vertisol and to evaluate the removal efficiency of heavy metals using Vetiver grass on different two mixed heavy metal contaminated soils. A pot experiment was conducted to compare the metal accumulation and overall efficiency of metal uptake by different plant parts (roots and shoots) on both tropical soils. After 3 and 6 months growing on laboratory conditions, Vetiver grass plants were harvested and heavy metal concentrations in shoot and root parts determined by Inductively Coupled Plasma - Atomic Emission Spectroscopy. The results indicate that at 3 and 6 moths, the shoot and root concentrations of heavy metals in Vetiver grass harvested in lixisol were higher than vertisol. For different plant parts, all metal concentrations were higher in root than in shoot, except Cu and Pb. At the 3 and 6 months, the BCF values > 1 for Cd, Cu and Zn in both soils showed Vetiver grass as an effective phyto-stabilizer for these metals. However, the TF values > 1 for Cd (lixisol), Mn, Zn Ni and Cr (vertisol) indicated the efficiency of Vetiver for phytoextraction. The results of this study showed that Vetiver is more effective in lixisol</span><span style="font-family:"">,</span><span style="font-family:""> but it can be used for remediation of both studied tropical soils from agricultural region of Burkina Faso. Nevertheless, considering the special limitations of the experimental conditions, further field monitoring is necessary to demonstrate the phytoremediation efficiency of Vetiver in agricultural soils under the climatic conditions of Burkina Faso.
基金the financial support granted by the Brazilian research funding institutions CNPq,CAPES and FAPESP.
文摘The Hall-Héroult process is used for alumina reduction by the use of graphite anodes even though it involves a high emission of carbon dioxide (CO2) and several other organic compounds. Proposals have been made aiming at substituting graphite for a single-phase SnO2-based ceramic with low resistivity and chemical resistance to cryolite, which is characterized as an inconsumable anode, reducing pollutant emissions. To this end, a wide range of studies were carried out on SnO2-based ceramics modified with ZnO as a densification aid doped with the promoters of electrical conductivity such as Nb2O5, Al2O3 and Sb2O3 through a mixture of oxides and hybrid sintering in a microwave oven. The pressed pellets were sintered in a microwave oven up to 1050℃ under a constant heating rate of 10℃/min. After sintering, the density was determined by the Archimedes method, the phases were then characterized by X-ray diffraction, the microstructure and chemical composition resulting from the sintered SnO2-based ceramics were also investigated by field emission scanning electron microscopy (FE-SEM) coupled with an energy-dispersive X-ray spectroscopy (EDS) and the electrical properties were determined by the measurements of the electric field x current density. A single-phase ceramic was obtained with a relative density of above 90% and electrical resistivity of 6.1 Ω·cm at room temperature. The ceramics obtained in this study could be a potential candidate as an inconsumable anode to replace the current fused coke used in the reduction of alumina.
基金supported by the European Union(EU)Horizon 2020 for the project InterLynk(Grant agreement:953169)Funda玢o para a Ciência e Tecnologia(10.54499/2022.04605.CEECIND/CP1720/CT0021,BI/UI89/10303/2022,PTDC/BTM-MAT/3201/2020,and PRT/BD/154735/2023)+3 种基金FCT/MEC(PIDDAC)Säo Paulo Research Foundation(FAPESP)grants#2018/12871-0,#2021/10844-8,and#2013/07296-2(CEPID)National Council for Scientific and Technological Development(CNPq)Coordination of Superior Level Staff Improvement(CAPES)Finance Code 001.
文摘Exploring the natural availability and intrinsic bioactivity of blood-derived proteins opens new avenues for fabricating bioactive and patient-specific solutions for biomedical applications.Despite their several advantages,their use as inks for 3D printing is limited due to suboptimal rheological properties.To address this,we propose a dual-step strategy based on the initial generation of blood protein-based bulk hydrogels encompassing pristine and photo-responsive protein mixtures to allow their mechanical granularization followed by jamming,establishing injectable and printable granular inks.In this study,two globular-based protein matrices-human platelet lysates(PL)and bovine serum albumin(BSA)-were used as granular inks for 3D printing.We hypothesize that nozzle jamming-in contrast to the typically employed centrifugal jamming-would render optimized results for the granular protein inks’processability.Printability was evaluated in filaments,scaffold grids,and convoluted structures.Taking advantage of the previously introduced photocurable moieties,post-printing photocrosslinking was used for the annealing of themicrogels,leading to increased scaffold mechanical stability and robustness.The nozzle jamming methodology imparted the best print performance and reproducibility,where PLMA-based inks outperformed the BSAMA-based.In addition,the microgel granular constructs allowed primary human-derived adipose stem cells to adhere and proliferate,whereas the PLMA-based ink demonstrated higher cell affinity and enhanced biological performance.We further demonstrated that bioinks could be developed from PLMA-based inks,showcasing high viability without compromising 3D printing performance.Overall,this study gives clear insights into the importance of the jamming process as well as the granularization outcome requirements for the obtention of highly reproducible granular inks for 3D printing.
文摘Aims and Methods We propose a standard protocol at the landscape to continental scale for examining to what extent the range of ecological conditions found in temperate latitudes explains the variations in climber species richness and traits.The protocol was tested in forests of the two Americas.The data set included 151 climber species.We selected four categorical traits and grouped these species into six clusters with regard to these traits.Floristic records of American forests were first gathered into alliances,second combined with bioclimatic indices(rainfall,temperature,continentality).We obtained a total of 59 vegetational units in which we calculated values of climber species richness and proportion of clusters.Vegetational units were ultimately gathered into five forest formations(characterized by leaf longevity).Wetlands and uplands were considered separately.Important Findings Our results emphasize clear trends in large-scale patterns of climber distribution,independently of taxonomy.Climber species richness(in particular woody climbers)peaks in moist and warm upland forests with oceanic climates,and where conifers are rare.In flooded areas,climber richness is also very high and peaks in seasonally flooded large floodplains.In ecological conditions of frost,dryness or lack of nutrients,climber species richness,abundance and trait diversity decline,resulting in the dominance of small,twining and deciduous life traits.
基金support of the Brazilian research financing institutions:CNPq,CAPES and FAPESP-CDMF 2013/07296-2.
文摘Literature has reported the synthesis of barium calcium titanates by various synthesis methods such as solid state reaction,co-precipitation and polymer precursors.These compounds are usually obtained using calcium carbonate(CaCO_(3)),barium carbonate(BaCO3)and titanium oxide as starting materials.This study investigated the effect of different starting reagents on the synthesis of Ba_(0.8)Ca_(0.2)TiO_(3)(BCT)by complex polymerization method(CPM).Two sets of starting precursors were used:titanium citrate,CaCO_(3)and BaCO3,and titanium citrate and Ba1-xCaxCO3 solid solution precursor.Samples were crystallized at a temperature range from 400℃to 700℃for different time.The obtained powders were characterized by X-ray diffraction(XRD),thermogravimetry(TG)and differential thermal analysis(DTA),and Raman and infrared spectroscopy.The infrared spectroscopy indicated that the chelation processes of Ba,Ca,Ti and CA ions are very similar.The results showed that the use of CaCO_(3)and BaCO3 or Ba1-xCaxCO3 solid solution as precursors does not affect the final properties of BCT powders obtained by CPM.
