Expanding urbanization and agricultural intensification across neighboring South Asia and East Asia have substantially threatened atmospheric condition over the Third Pole(TP)during the past few decades.Whether the at...Expanding urbanization and agricultural intensification across neighboring South Asia and East Asia have substantially threatened atmospheric condition over the Third Pole(TP)during the past few decades.Whether the atmospheric condition over the TP is still as clean as a representative of the regional background draws great concern.In this work,great differences in levoglucosan concentration within/above the atmospheric boundary layer height are revealed.Levoglucosan results support the hypothesis that atmospheric pollutants in the mid-troposphere over the TP are mainly affected by long-range transport,although there are some local biomass burning emissions in residential areas.In addition,levoglucosan concentration in the midtroposphere over the TP is at the same magnitude as marine and polar regions,but about 2–3 magnitudes lower than neighboring densely-populated Asian regions.With insights of levoglucosan records,this work therefore proves that the high-altitude TP still has largely pristine atmospheric conditions,and is one of the cleanest remote regions on the Earth.展开更多
Pristine habitats serve as ecological resource for educational services and the conservation of biodiversity. The need to maintain a balance between nature and development is very important. When pristine habitats fac...Pristine habitats serve as ecological resource for educational services and the conservation of biodiversity. The need to maintain a balance between nature and development is very important. When pristine habitats face changes due to anthropogenic activities, species erosion sets in and this will eventually lead to extinction. This subtle move in most cases is unnoticed until the effects are established. The pristine habitats in Ugep are faced with this challenge. The Ugep Urban Landuse Master Plan and Ugep Orthophoto map [1] have been used to identify the pristine habitats and further calculate the total landmass to be approximately 855.38 hectares. Ten (10) pristine habitats were identified within the residential blocks along the drainage corridors of Loblo, Isayi, Mma Oden, Kiwei, Ewiden and Oganghwen. The pristine block at Njelokoko-2 has the highest landmass, 201.01 hectares, representing 23.50 percent while Njelokoko-1 has the least landmass, 18.99 (2.22 percent). The spatial turnover of the species composition shows a trend of direct proportion with the landmass size and anthropogenic activities in the pristine habitats. Tree species such as Albizia zygia and Artocarpus communis rarely occurred together with other tree species. Among the bird species, it was observed that Dendropes goerae, Milvus migrans, Pica pica, and Streptopelia senegalensis roost, breed and feed in pristine habitats with emergent trees while Halocyno leucoephala, Halocyno malimbicus, Frasena clnernscens, Streptopelia semitorguata and Crimifer piscator are restricted to narrow corridors of pristine habitats along stream buffers. The nature that the pristine habitat portends and the species observed in such highly urbanized context as Ugep, are very important in conservation planning and meeting the urban challenges.展开更多
Metal-organic frameworks(MOFs)have caused extensive attention attributed to their widespread applications including electrocatalysis by virtue of their distinctive structural characteristics.However,the direct applica...Metal-organic frameworks(MOFs)have caused extensive attention attributed to their widespread applications including electrocatalysis by virtue of their distinctive structural characteristics.However,the direct application of pristine MOFs as bifunctional electrocatalysts is quite challenging due to their insufficient active sites and poor electrical conductivity.In this research,the ultrathin tri-metal(Fe,Co,and V)doped FeCoV-NiMOF nanosheet arrays were prepared through a facile hydrothermal method.Benefiting from the distinctive ultrathin(1.5 nm)nanosheet arrays and electronic structure reconfiguration induced by heteroatom doping,the prepared FeCoV-NiMOF displays the low overpotentials of 238,309,and 408 mV for oxygen evolution reaction(OER)and 144,255,and 349 mV for hydrogen evolution reaction(HER)at the current densities of 10,100,and 1000 mA cm^(−2),respectively,outperforming the vast majority of previously reported bifunctional pristine MOFs.The electrolytic cell utilizing FeCoV-NiMOF as both cathode and anode requires just 1.61 V to attain 10 mA cm^(−2)and displays superior stability of 100 h at 100 mA cm^(−2).In the anion exchange membrane electrolyzer,as-prepared FeCoV-NiMOF needs a low cell voltage of 2.16 V at 500 mA cm^(−2)for effective overall water splitting,demonstrating its substantial potential as bifunctional electrodes for H2 production.The viable and efficient strategy in this study exhibits great prospects to enrich the exploration of bifunctional MOF-based electrocatalysts with superior performance for renewable energy conversion.展开更多
Graphene is a promising material as both active components and additives in electrochemical energy storage devices. The properties of graphene strongly depend on the fabrication methods. The applications of reduced gr...Graphene is a promising material as both active components and additives in electrochemical energy storage devices. The properties of graphene strongly depend on the fabrication methods. The applications of reduced graphene oxide as electrode materials have been well studied and reviewed, but the using of "pristine" graphene as electrode material for energy storage is still a new topic. In this paper, we review state-of-the-art progress in the fabrication of "pristine" graphene by different methods and the electrochemical performance of graphene-based electrodes. The achievements in this area will be summarized and compared with the graphene oxide route in terms of cost, scalability, material properties and performances, and the challenges in these methods will be discussed as well.展开更多
The pristine point of zero charge(p.p.z.c)and zeta potential as a function of pH of boehmite oxide/hydroxide(α-Al_(2)O_(3)·H_(2)O)have been determined for three filter media.The active component in the first two...The pristine point of zero charge(p.p.z.c)and zeta potential as a function of pH of boehmite oxide/hydroxide(α-Al_(2)O_(3)·H_(2)O)have been determined for three filter media.The active component in the first two filter media is boehmite nanofibers,only 2 nm in diameter and about 300 nm long.Boehmite nanofibers create high zeta potential(ζtrue≥46 mV)in aqueous solutions in the pH range of 3–8.The p.p.z.c.values were determined to be 11.60±0.15 for nanofibers grafted onto microglass fibers and 11.40±0.15 for agglomerated nanofibers.In the third filter media,a boehmite nanolayer in the form of monocrystalline oxide/hydroxide with a thickness of approximately 1.2 nm is electroadhesively deposited onto siliceous support material with large surface area of about 50 m^(2)/g,therefore forming a highly electropositive composite of boehmite nanolayer on the second highly electronegative solid.Boehmite’s oxide-hydroxide nanolayer surface creates high zeta potential(ζtrue≥50 mV)in aqueous solutions in the pH range of 3–8.The p.p.z.c.value was determined to be 11.38±0.15.The reported values are within accuracy,but they are much higher than the values reported in the literature.X-ray powder diffraction data were supplemented by microscopy,infrared spectroscopy in order to characterize fully synthetic boehmite surfaces.展开更多
In recent studies of two-dimensional(2D)nanomaterial-based solid lubricants,the importance of durability has been emerging for real engineering-scale applications.To achieve this,a transfer layer formation is essentia...In recent studies of two-dimensional(2D)nanomaterial-based solid lubricants,the importance of durability has been emerging for real engineering-scale applications.To achieve this,a transfer layer formation is essential to prevent the wear of the mechanical systems.However,it has been challenging for pristine graphene(PG)to induce a material transfer due to chemical inertness.In this study,we suggest an easy-to-process strategy to promote the huge material transfer of the PG onto the counterpart contacting material.We utilized graphene oxide(GO)as a gluing layer between the PG film and the counterpart contact surface to realize the superior tribological performance.The high interaction energy of the GO from its functional groups makes a contribution to the material transfer of PG,which is unveiled by a systematic analysis of the counterpart contact surface and the wear track.The huge solid transfer layer not only makes a wear-resistant contact interface between the transfer layer and the underlying film by densification and oxidation,but also reduces surface interaction energies,finally resulting in a significant improvement in durability.展开更多
Industrial production and domestic discharge produce a large amount of oily wastewater, which seriously affects the stability of the ecological environment. Membrane separation technology provides another path to trea...Industrial production and domestic discharge produce a large amount of oily wastewater, which seriously affects the stability of the ecological environment. Membrane separation technology provides another path to treating oily wastewater. And appropriate surface modification of the membrane helps to achieve high efficiency of treating oily wastewater. With green, economy and stability been more concerned.The focal research reports a completely biodegradable all cellulose composite filter paper(ACCFP) composed of Ⅰ-cellulose macrofibers and Ⅱ-cellulose matrix. It is a simple one-step impregnation method to adjust the surface microstructure of the pristine filter paper(PFP), and it does not involve with chemical reaction. The pre-wetted ACCFP consist of Ⅱ-cellulose hydrogel and Ⅰ-cellulose reinforcement in the process of oil-water separation. This layer of hydrogel is the fundamental to underwater superoleophobicity, which determines their eligibility for applications of efficient oil-water mixture or oil-in-water(oil/water) emulsion separation. The separation efficiency of oil-water mixture and oil/water emulsion exceed 95% and 99.9%, respectively. In addition, excellent mechanical properties of ACCFP in dry and wet conditions ensure its stability in service and prolong service life in applications. The focal study provides a new method for high-performance oil-water separation and it is more in line with sustainable chemistry.展开更多
Simulations from the Weather Research and Forecasting Model, inline coupled with chemistry, were used to examine the fate of particulate matter with diameter of 10 μm or less (PM10) in Glacier Bay, Alaska during the ...Simulations from the Weather Research and Forecasting Model, inline coupled with chemistry, were used to examine the fate of particulate matter with diameter of 10 μm or less (PM10) in Glacier Bay, Alaska during the 2008 tourist season. The simulations demonstrated that mesoscale and synoptic scale weather systems affect the residence time of PM10, the magnitude of concentrations, and its transport in and out of Glacier Bay. Strong inversions exceeding 2 K (100 m)-1 cause notable trapping of pollutants from cruise-ship emissions, increasing PM10 concentrations up to 43% compared to days with cruise-ship visits without the presence of an inversion. Inversions occurred locally in Glacier Bay on 42% of the 124-day tourist season with an average lifetime of 9 h. Pollutants occasionally originated from outside the National Park when southerly winds advected pollutants from ship traffic in Icy Strait. Occasionally, orographically forced lifting over the Fairweather Mountains transported pollutants from the Gulf of Alaska into Glacier Bay. While hourly (daily) PM10 concentrations reached ~44 μg·m-3 (22 μg·m-3) in some areas of Glacier Bay, overall seasonal average PM10 concentrations were below 2 μg·m-3. Despite up to two cruise-ship visits per day, Glacier Bay still has pristine air quality. Surface and upper air meteorological state variables were evaluated through an extensive network of surface and radiosonde observations, which demonstrated that the model was able to capture the meteorological conditions well.展开更多
The AraguaiaRiver Basincovers a considerable extent of Brazilian Savanna (locally called Cerrado) and part of Amazon Tropical Rainforest, embracing high biodiversity and a vast flooding area. This region has been conv...The AraguaiaRiver Basincovers a considerable extent of Brazilian Savanna (locally called Cerrado) and part of Amazon Tropical Rainforest, embracing high biodiversity and a vast flooding area. This region has been converted to agricultural lands since 1970s, for the past four decades, leading to a fragmented landscape that holds one of the few large remaining blocks of Cerrado primary vegetation. Therefore, to assess the degree of preservation of this area a 2007 primary vegetation map was derived through Boolean operations using land use and land cover maps from 1975, 1985, 1996 and 2007, from digital classification of Landsat MSS and TM images. To evaluate the role of driving factors on the presence of pristine vegetation, a logistic regression analyses was performed. Tested factors were: distance from roads and cities, terrain slope, land tenure, soil fertility and flooding. We found statistical significant values (p nous lands, wetlands and areas with low fertility have positive influence on the presence and maintenance of these pristine areas. The occurrence of original vegetation in many cases is associated with environmental constraints that difficult or do not allow agricultural use. Analysis of physical and political factors, which may have direct or indirect influence on the conservation and degradation of native vegetation are very important for the comprehension of the dynamics of regional land use, and provide supporting information for a more efficient and sustainable regional landscape planning.展开更多
Managers at Glacier Bay National Park must annually determine the allowable number of cruise-ship entries into the park. This decision considers how differences in visitor volume may affect park resources. This study ...Managers at Glacier Bay National Park must annually determine the allowable number of cruise-ship entries into the park. This decision considers how differences in visitor volume may affect park resources. This study quantified the impacts to air quality and visibility under different ship quotas using simulations with the Weather Research and Forecasting model inline coupled with chemistry. Results of the simulation assuming two entries per day for May 15 to September 15, 2008 (QTA;248 ship entries representing a 35% increase) were compared to those of the 2008 cruise-ship activity (REF;184) during that timeframe. A simulation without anthropogenic emissions (CLN) served to assess the overall impacts of cruise-ship emissions on visibility and air quality in Glacier Bay. Compared to REF, the increased entry quotas shifted chemical regimes and aerosol composition, depending upon thermodynamical conditions, and ambient concentrations. On days with notable regime shifts, sulfur-dioxide concentrations deceased while ammonium-sulfate aerosol concentrations increased. The increased quotas also altered the fine-to-coarse aerosol ratios in both directions despite constant ratio of fine-to-coarse aerosol emissions. In Glacier Bay, the days with worst visibility coincided with high relative humidity, although this relationship varied by scenario. On the 20% worst days, mean visibility was slightly better in CLN (mean haze index over Glacier Bay waters = 2.9 dv) than in REF ( = 3.1 dv). While increased emissions in QTA reduced mean visibility by 0.1 dv, the 10th, 50th and 90th percentile of haze indices remained identical to those in REF. Best (worst) visibility occurred on the same days in REF and QTA due to emission impacts, but on different days than in CLN because relative humidity solely governed visibility in CLN. While calm wind played no role for visibility in CLN, wind speed gained similar importance for visibility as relative humidity in REF and QTA. Overall, increasing ship quotas would only marginally affect air quality and visibility as compared to REF, although even small changes in these parameters need careful consideration in the context of conserving the values of Glacier Bay.展开更多
In this study,two fullerenes(C60,C70)and their methano-substitutions(PC61BM,PC71BM),as electron transport materials(ETMs)in perovskite solar cells(Pero-SCs),were systematically studied.As being used as ETMs,methanoful...In this study,two fullerenes(C60,C70)and their methano-substitutions(PC61BM,PC71BM),as electron transport materials(ETMs)in perovskite solar cells(Pero-SCs),were systematically studied.As being used as ETMs,methanofullerenes,though with lower electron mobility compared to the counterpart pristine fullerenes,lead to higher power conversion efficiencies(PCEs)of Pero-SCs.The difference is likely caused by the fill-out vacancies and smoother morphology of the interfaces between ETM and perovskite layers,as they were prepared by different methods.In addition,compared to C60 and PC61BM,C70 and PC71BM showed priority in terms of short-circuit current density,which should be attributed to fast free charge extraction abilities.展开更多
Graphene oxide(GO)membranes have received considerable attention owing to their outstanding water-permeation properties;however,the effect of the membrane’s microstructures(such as the distribution of oxidized and pr...Graphene oxide(GO)membranes have received considerable attention owing to their outstanding water-permeation properties;however,the effect of the membrane’s microstructures(such as the distribution of oxidized and pristine regions)on the transport mechanism remains unclear.In this study,we performed molecular simulations to explore the permeation of a water-ethanol mixture using a new type of Janus GO membranes with different orientations of oxidized and pristine surfaces.The results indicate that the oxidized upper surface endows the GO membrane with considerable water-capture capability and the in-built oxidized interlayer promotes the effective vertical diffusion of water molecules.Consequently,using the optimized Janus GO membrane,infinite water selectivity and outstanding water flux(-40.9 kg·m^(-2) h^(-1))were achieved.This study contributes to explaining the role of oxidized regions in water permeation via GO membranes and suggests that Janus GO membranes could be used as potential candidates for water-ethanol separation.展开更多
基金the Youth Innovation Promotion Association CAS(2020071)Chinese Academy of Sciences(YIPA-2020071,XDA20060200)+1 种基金the National Natural Science Foundation of China(41701078,41805127)the Second Tibetan Plateau Scientific Expedition and Research(2019QZKK0201).
文摘Expanding urbanization and agricultural intensification across neighboring South Asia and East Asia have substantially threatened atmospheric condition over the Third Pole(TP)during the past few decades.Whether the atmospheric condition over the TP is still as clean as a representative of the regional background draws great concern.In this work,great differences in levoglucosan concentration within/above the atmospheric boundary layer height are revealed.Levoglucosan results support the hypothesis that atmospheric pollutants in the mid-troposphere over the TP are mainly affected by long-range transport,although there are some local biomass burning emissions in residential areas.In addition,levoglucosan concentration in the midtroposphere over the TP is at the same magnitude as marine and polar regions,but about 2–3 magnitudes lower than neighboring densely-populated Asian regions.With insights of levoglucosan records,this work therefore proves that the high-altitude TP still has largely pristine atmospheric conditions,and is one of the cleanest remote regions on the Earth.
文摘Pristine habitats serve as ecological resource for educational services and the conservation of biodiversity. The need to maintain a balance between nature and development is very important. When pristine habitats face changes due to anthropogenic activities, species erosion sets in and this will eventually lead to extinction. This subtle move in most cases is unnoticed until the effects are established. The pristine habitats in Ugep are faced with this challenge. The Ugep Urban Landuse Master Plan and Ugep Orthophoto map [1] have been used to identify the pristine habitats and further calculate the total landmass to be approximately 855.38 hectares. Ten (10) pristine habitats were identified within the residential blocks along the drainage corridors of Loblo, Isayi, Mma Oden, Kiwei, Ewiden and Oganghwen. The pristine block at Njelokoko-2 has the highest landmass, 201.01 hectares, representing 23.50 percent while Njelokoko-1 has the least landmass, 18.99 (2.22 percent). The spatial turnover of the species composition shows a trend of direct proportion with the landmass size and anthropogenic activities in the pristine habitats. Tree species such as Albizia zygia and Artocarpus communis rarely occurred together with other tree species. Among the bird species, it was observed that Dendropes goerae, Milvus migrans, Pica pica, and Streptopelia senegalensis roost, breed and feed in pristine habitats with emergent trees while Halocyno leucoephala, Halocyno malimbicus, Frasena clnernscens, Streptopelia semitorguata and Crimifer piscator are restricted to narrow corridors of pristine habitats along stream buffers. The nature that the pristine habitat portends and the species observed in such highly urbanized context as Ugep, are very important in conservation planning and meeting the urban challenges.
基金supported by the National Science Fund for Distinguished Young Scholars(No.52025041)the National Natural Science Foundation of China(Nos.51974021,51902020,51904021)+3 种基金the Fundamental Research Funds for the Central Universities(Nos.FRF-TP-18-045A1 and FRF-TP-19-004B2Z)the National Postdoctoral Program for Innovative Talents(No.BX20180034)the Open Foundation of Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials,Guangxi University(No.2021GXYSOF12)the Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities)(No.FRF-IDRY-21-028).
文摘Metal-organic frameworks(MOFs)have caused extensive attention attributed to their widespread applications including electrocatalysis by virtue of their distinctive structural characteristics.However,the direct application of pristine MOFs as bifunctional electrocatalysts is quite challenging due to their insufficient active sites and poor electrical conductivity.In this research,the ultrathin tri-metal(Fe,Co,and V)doped FeCoV-NiMOF nanosheet arrays were prepared through a facile hydrothermal method.Benefiting from the distinctive ultrathin(1.5 nm)nanosheet arrays and electronic structure reconfiguration induced by heteroatom doping,the prepared FeCoV-NiMOF displays the low overpotentials of 238,309,and 408 mV for oxygen evolution reaction(OER)and 144,255,and 349 mV for hydrogen evolution reaction(HER)at the current densities of 10,100,and 1000 mA cm^(−2),respectively,outperforming the vast majority of previously reported bifunctional pristine MOFs.The electrolytic cell utilizing FeCoV-NiMOF as both cathode and anode requires just 1.61 V to attain 10 mA cm^(−2)and displays superior stability of 100 h at 100 mA cm^(−2).In the anion exchange membrane electrolyzer,as-prepared FeCoV-NiMOF needs a low cell voltage of 2.16 V at 500 mA cm^(−2)for effective overall water splitting,demonstrating its substantial potential as bifunctional electrodes for H2 production.The viable and efficient strategy in this study exhibits great prospects to enrich the exploration of bifunctional MOF-based electrocatalysts with superior performance for renewable energy conversion.
基金supported by the National Natural Science Foundation of China(Grant Nos.51125009&91434118)the National Natural Science Foundation for Creative Research Group(Grant No.21221061)the Hundred Talents Program of the Chinese Academy of Sciences
文摘Graphene is a promising material as both active components and additives in electrochemical energy storage devices. The properties of graphene strongly depend on the fabrication methods. The applications of reduced graphene oxide as electrode materials have been well studied and reviewed, but the using of "pristine" graphene as electrode material for energy storage is still a new topic. In this paper, we review state-of-the-art progress in the fabrication of "pristine" graphene by different methods and the electrochemical performance of graphene-based electrodes. The achievements in this area will be summarized and compared with the graphene oxide route in terms of cost, scalability, material properties and performances, and the challenges in these methods will be discussed as well.
文摘The pristine point of zero charge(p.p.z.c)and zeta potential as a function of pH of boehmite oxide/hydroxide(α-Al_(2)O_(3)·H_(2)O)have been determined for three filter media.The active component in the first two filter media is boehmite nanofibers,only 2 nm in diameter and about 300 nm long.Boehmite nanofibers create high zeta potential(ζtrue≥46 mV)in aqueous solutions in the pH range of 3–8.The p.p.z.c.values were determined to be 11.60±0.15 for nanofibers grafted onto microglass fibers and 11.40±0.15 for agglomerated nanofibers.In the third filter media,a boehmite nanolayer in the form of monocrystalline oxide/hydroxide with a thickness of approximately 1.2 nm is electroadhesively deposited onto siliceous support material with large surface area of about 50 m^(2)/g,therefore forming a highly electropositive composite of boehmite nanolayer on the second highly electronegative solid.Boehmite’s oxide-hydroxide nanolayer surface creates high zeta potential(ζtrue≥50 mV)in aqueous solutions in the pH range of 3–8.The p.p.z.c.value was determined to be 11.38±0.15.The reported values are within accuracy,but they are much higher than the values reported in the literature.X-ray powder diffraction data were supplemented by microscopy,infrared spectroscopy in order to characterize fully synthetic boehmite surfaces.
基金supported by the National Research Foundation of Korea(NRF)Global Basic Research Laboratory grant funded by the Korea government(MSIT)(No.RS-2025-02216195)by the Korea Institute of Energy Technology Evaluation and Planning(KETEP)grant funded by the Korea government(MOTIE)(No.20214000000140).
文摘In recent studies of two-dimensional(2D)nanomaterial-based solid lubricants,the importance of durability has been emerging for real engineering-scale applications.To achieve this,a transfer layer formation is essential to prevent the wear of the mechanical systems.However,it has been challenging for pristine graphene(PG)to induce a material transfer due to chemical inertness.In this study,we suggest an easy-to-process strategy to promote the huge material transfer of the PG onto the counterpart contacting material.We utilized graphene oxide(GO)as a gluing layer between the PG film and the counterpart contact surface to realize the superior tribological performance.The high interaction energy of the GO from its functional groups makes a contribution to the material transfer of PG,which is unveiled by a systematic analysis of the counterpart contact surface and the wear track.The huge solid transfer layer not only makes a wear-resistant contact interface between the transfer layer and the underlying film by densification and oxidation,but also reduces surface interaction energies,finally resulting in a significant improvement in durability.
基金the financial support from the National Key R&D Program of China (no. 2018YFB1501602)Science Foundation of Shanxi Province, China (Grant no. 201901D111006ZD)+1 种基金Fund for Shanxi “1331 project”Shanxi Province Platform Base and Talent Special Fund (no. 201705D211023)。
文摘Industrial production and domestic discharge produce a large amount of oily wastewater, which seriously affects the stability of the ecological environment. Membrane separation technology provides another path to treating oily wastewater. And appropriate surface modification of the membrane helps to achieve high efficiency of treating oily wastewater. With green, economy and stability been more concerned.The focal research reports a completely biodegradable all cellulose composite filter paper(ACCFP) composed of Ⅰ-cellulose macrofibers and Ⅱ-cellulose matrix. It is a simple one-step impregnation method to adjust the surface microstructure of the pristine filter paper(PFP), and it does not involve with chemical reaction. The pre-wetted ACCFP consist of Ⅱ-cellulose hydrogel and Ⅰ-cellulose reinforcement in the process of oil-water separation. This layer of hydrogel is the fundamental to underwater superoleophobicity, which determines their eligibility for applications of efficient oil-water mixture or oil-in-water(oil/water) emulsion separation. The separation efficiency of oil-water mixture and oil/water emulsion exceed 95% and 99.9%, respectively. In addition, excellent mechanical properties of ACCFP in dry and wet conditions ensure its stability in service and prolong service life in applications. The focal study provides a new method for high-performance oil-water separation and it is more in line with sustainable chemistry.
基金the National Park Service for financial assistance(contract P11AT30883/P11AC90465).
文摘Simulations from the Weather Research and Forecasting Model, inline coupled with chemistry, were used to examine the fate of particulate matter with diameter of 10 μm or less (PM10) in Glacier Bay, Alaska during the 2008 tourist season. The simulations demonstrated that mesoscale and synoptic scale weather systems affect the residence time of PM10, the magnitude of concentrations, and its transport in and out of Glacier Bay. Strong inversions exceeding 2 K (100 m)-1 cause notable trapping of pollutants from cruise-ship emissions, increasing PM10 concentrations up to 43% compared to days with cruise-ship visits without the presence of an inversion. Inversions occurred locally in Glacier Bay on 42% of the 124-day tourist season with an average lifetime of 9 h. Pollutants occasionally originated from outside the National Park when southerly winds advected pollutants from ship traffic in Icy Strait. Occasionally, orographically forced lifting over the Fairweather Mountains transported pollutants from the Gulf of Alaska into Glacier Bay. While hourly (daily) PM10 concentrations reached ~44 μg·m-3 (22 μg·m-3) in some areas of Glacier Bay, overall seasonal average PM10 concentrations were below 2 μg·m-3. Despite up to two cruise-ship visits per day, Glacier Bay still has pristine air quality. Surface and upper air meteorological state variables were evaluated through an extensive network of surface and radiosonde observations, which demonstrated that the model was able to capture the meteorological conditions well.
基金Funding and scholarship for this study were provided by FAPESP and Milenio/CNPq(proc.2003/13172-2,2007/01686-2 and 420199/2005-5,respectively)support from United States National Aeronautics and Space Administration(NASA)-Land-Cover and Land-Use Change Program(LCLUC)(NNX11AE56G).
文摘The AraguaiaRiver Basincovers a considerable extent of Brazilian Savanna (locally called Cerrado) and part of Amazon Tropical Rainforest, embracing high biodiversity and a vast flooding area. This region has been converted to agricultural lands since 1970s, for the past four decades, leading to a fragmented landscape that holds one of the few large remaining blocks of Cerrado primary vegetation. Therefore, to assess the degree of preservation of this area a 2007 primary vegetation map was derived through Boolean operations using land use and land cover maps from 1975, 1985, 1996 and 2007, from digital classification of Landsat MSS and TM images. To evaluate the role of driving factors on the presence of pristine vegetation, a logistic regression analyses was performed. Tested factors were: distance from roads and cities, terrain slope, land tenure, soil fertility and flooding. We found statistical significant values (p nous lands, wetlands and areas with low fertility have positive influence on the presence and maintenance of these pristine areas. The occurrence of original vegetation in many cases is associated with environmental constraints that difficult or do not allow agricultural use. Analysis of physical and political factors, which may have direct or indirect influence on the conservation and degradation of native vegetation are very important for the comprehension of the dynamics of regional land use, and provide supporting information for a more efficient and sustainable regional landscape planning.
基金the National Park Service(Cooperative Ecosystem Studies Unit,contract P11AT30883/P11AC90465)for financial support.
文摘Managers at Glacier Bay National Park must annually determine the allowable number of cruise-ship entries into the park. This decision considers how differences in visitor volume may affect park resources. This study quantified the impacts to air quality and visibility under different ship quotas using simulations with the Weather Research and Forecasting model inline coupled with chemistry. Results of the simulation assuming two entries per day for May 15 to September 15, 2008 (QTA;248 ship entries representing a 35% increase) were compared to those of the 2008 cruise-ship activity (REF;184) during that timeframe. A simulation without anthropogenic emissions (CLN) served to assess the overall impacts of cruise-ship emissions on visibility and air quality in Glacier Bay. Compared to REF, the increased entry quotas shifted chemical regimes and aerosol composition, depending upon thermodynamical conditions, and ambient concentrations. On days with notable regime shifts, sulfur-dioxide concentrations deceased while ammonium-sulfate aerosol concentrations increased. The increased quotas also altered the fine-to-coarse aerosol ratios in both directions despite constant ratio of fine-to-coarse aerosol emissions. In Glacier Bay, the days with worst visibility coincided with high relative humidity, although this relationship varied by scenario. On the 20% worst days, mean visibility was slightly better in CLN (mean haze index over Glacier Bay waters = 2.9 dv) than in REF ( = 3.1 dv). While increased emissions in QTA reduced mean visibility by 0.1 dv, the 10th, 50th and 90th percentile of haze indices remained identical to those in REF. Best (worst) visibility occurred on the same days in REF and QTA due to emission impacts, but on different days than in CLN because relative humidity solely governed visibility in CLN. While calm wind played no role for visibility in CLN, wind speed gained similar importance for visibility as relative humidity in REF and QTA. Overall, increasing ship quotas would only marginally affect air quality and visibility as compared to REF, although even small changes in these parameters need careful consideration in the context of conserving the values of Glacier Bay.
基金the National Natural Science Foundation of China(51303118,91333204)the Natural Science Foundation of Jiangsu Province(BK20130289)+3 种基金the Ph.D.Programs Foundation of Ministry of Education of China(20133201120008)the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Scientific Research Foundation for Returned Scholars,Ministry of Education of ChinaBeijing National Laboratory for Molecular Sciences,State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials
文摘In this study,two fullerenes(C60,C70)and their methano-substitutions(PC61BM,PC71BM),as electron transport materials(ETMs)in perovskite solar cells(Pero-SCs),were systematically studied.As being used as ETMs,methanofullerenes,though with lower electron mobility compared to the counterpart pristine fullerenes,lead to higher power conversion efficiencies(PCEs)of Pero-SCs.The difference is likely caused by the fill-out vacancies and smoother morphology of the interfaces between ETM and perovskite layers,as they were prepared by different methods.In addition,compared to C60 and PC61BM,C70 and PC71BM showed priority in terms of short-circuit current density,which should be attributed to fast free charge extraction abilities.
基金This work was financially supported by the National Natural Science Foundation of China(Grant Nos.21922805,21776125).
文摘Graphene oxide(GO)membranes have received considerable attention owing to their outstanding water-permeation properties;however,the effect of the membrane’s microstructures(such as the distribution of oxidized and pristine regions)on the transport mechanism remains unclear.In this study,we performed molecular simulations to explore the permeation of a water-ethanol mixture using a new type of Janus GO membranes with different orientations of oxidized and pristine surfaces.The results indicate that the oxidized upper surface endows the GO membrane with considerable water-capture capability and the in-built oxidized interlayer promotes the effective vertical diffusion of water molecules.Consequently,using the optimized Janus GO membrane,infinite water selectivity and outstanding water flux(-40.9 kg·m^(-2) h^(-1))were achieved.This study contributes to explaining the role of oxidized regions in water permeation via GO membranes and suggests that Janus GO membranes could be used as potential candidates for water-ethanol separation.
