This review describes dietary fibres originating from a range of foods,particularly in relation to their plant cell walls.It explores the categorization of dietary fibres into "soluble" or "insoluble&qu...This review describes dietary fibres originating from a range of foods,particularly in relation to their plant cell walls.It explores the categorization of dietary fibres into "soluble" or "insoluble".It also emphasizes dietary fibre fermentability,in terms of describing how the gastro-intestinal tract(GIT) microbiota respond to a selection of fibres from these categories.Food is categorized into cereals,legumes,fruits and vegetables.Mention is also made of example whole foods and why differences in physico-chemical characteristics between "purified" and "non-purified"food components are important in terms of health.Lastly,recommendations are made as to how dietary fibre could be classified differently,in relation to its functionality in terms of fermentability,rather than only its solubility.展开更多
Tumor cell proliferation, infiltration, migration, and neovascularization are known causes of treatment resistance in glioblastoma multiforme(GBM). The purpose of this study was to determine the effect of radiation on...Tumor cell proliferation, infiltration, migration, and neovascularization are known causes of treatment resistance in glioblastoma multiforme(GBM). The purpose of this study was to determine the effect of radiation on the growth characteristics of primary human GBM developed in a nude rat. Primary GBM cells grown from explanted GBM tissues were implanted orthotopically in nude rats. Tumor growth was confirmed by magnetic resonance imaging on day 77(baseline) after implantation. The rats underwent irradiation to a dose of 50 Gy delivered subcuratively on day 84 postimplantation(n = 8), or underwent no radiation(n = 8). Brain tissues were obtained on day 112(nonirradiated) or day 133(irradiated). Immunohistochemistry was performed to determine tumor cell proliferation(Ki-67) and to assess the expression of infiltration marker(matrix metalloproteinase-2, MMP-2) and cell migration marker(CD44). Tumor neovascularization was assessed by microvessel density using von-Willebrand factor(vWF) staining. Magnetic resonance imaging showed well-developed, infiltrative tumors in 11 weeks postimplantation. The proportion of Ki-67-positive cells in tumors undergoing radiation was(71 ± 15)% compared with(25 ± 12)% in the nonirradiated group(P = 0.02). The number of MMP-2-positive areas and proportion of CD44-positive cells were also high in tumors receiving radiation, indicating great invasion and infiltration. Microvessel density analysis did not show a significant difference between nonirradiated and irradiated tumors. Taken together, we found that subcurative radiation significantly increased proliferation, invasion, and migration of primary GBM. Our study provides insights into possible mechanisms of treatment resistance following radiation therapy for GBM.展开更多
Purpose:This article investigates the role of private supplementary tutoring in Denmark in light of the country’s pedagogical traditions in schools and leisure spheres.Design/Approach/Methods:Although tutoring activi...Purpose:This article investigates the role of private supplementary tutoring in Denmark in light of the country’s pedagogical traditions in schools and leisure spheres.Design/Approach/Methods:Although tutoring activities are increasing,the phenomenon is not as prevalent in Denmark as in many other countries.In this article,we look into the history of Danish pedagogy for answers as to why this is the case.In the analytical sections of the article,we include research on parental values of child-rearing,as well as findings from a pilot study on Danish families purchasing private supplementary tutoring,the public debate about private tutoring,and contemporary youth research.Findings:With a solid emphasis on democracy and equality in Danish pedagogy,the conditions for increasing private supplementary tutoring in Denmark have been challenged.However,a current focus on global competition,formal competencies,and higher academic performance among children and young people suggests that providers of private tutoring perhaps face a brighter future—also in Denmark.Originality/Value:This article addresses a new field of qualitative research on private supplementary tutoring in Denmark and may be a platform for further reflection and empirical research.展开更多
Epidemiological studies have demonstrated reduced risk of developing cancer upon consumption of diets rich in cruciferous vegetables. This chemoprevention has been largely attributed to the presence of the natural pro...Epidemiological studies have demonstrated reduced risk of developing cancer upon consumption of diets rich in cruciferous vegetables. This chemoprevention has been largely attributed to the presence of the natural products glu- cosinolates, particularly the methionine-derived glucoraphanin from broccoli. Improved nutrition by functional foods or health-promoting dietary supplements is an attractive means for prevention of lifestyle-based diseases. Towards this goal, we have engineered the glucoraphanin pathway into tobacco. First, we engineered elongation of the side chain of methionine to produce the key intermediate dihomo-methionine. This process is catalyzed through two cycles in a chain-elongation pathway that takes place partly in the cytosol and partly in the chloroplast. Second, by coupling the five enzymes of the chain-elongation pathway to eight enzymes of the glucosinolate pathway, we show production of glucoraphanin together with other glucosinolates derived from chain-elongated isoleucine and/or leucine. The conver- sion of methionine to glucoraphanin is obtained via 14 intermediates. Demonstrating the production of the high-value glucoraphanin in a heterologous host has great potential in the food and medicinal industry as a means to generate a stable, rich source of glucoraphanin for the benefit of human health.展开更多
Nitrogen oxides (NO<sub>x</sub>) in urban air close to ground have significant health implications. Restrictions in traffic, mandatory use of catalytic converters on vehicles, and novel photocatalytic coat...Nitrogen oxides (NO<sub>x</sub>) in urban air close to ground have significant health implications. Restrictions in traffic, mandatory use of catalytic converters on vehicles, and novel photocatalytic coatings on surfaces contribute to reducing the level of NO<sub>x</sub> in cities. The aim of this study is to establish environmental profiles of NO<sub>x</sub> removal by a Three-Way Catalyst (TWC) car converter and by a photocatalytic surface coating (for asphalt and concrete pavements) for fostering technological development in reducing the levels of NO<sub>x</sub> in urban air. We assessed the environmental performance for the removal of 1 kg NO<sub>x</sub> by the two technologies with Life Cycle Assessment (LCA;EF.3 impact assessment method). In order to do so, we established Life-Cycle-Inventory (LCI) data representing production, operation and end-of-life of the two technologies based on data from literature and industry. The production of photocatalytic surface coatings, used on concrete and asphalt, has environmental loads two orders of magnitude lower than the environmental benefits of NO<sub>x</sub> reduction expressed as a reduction in Photochemical Ozone Formation (POF), Acidification (A), and Terrestrial Eutrophication (TE). The vehicle catalytic converter shows similar results except that the use of rare earth elements in the production constitutes a significant load to Freshwater Ecotoxicity (FET) and that additional use of fuel during operation induces a modest Climate Change (CC) impact. For both technologies, the environmental benefits of reducing NO<sub>x</sub> far exceed any adverse environmental aspects of the production of the technologies.展开更多
Aims Beech(Fagus sylvatica L.)is an important species in natural and managed forests in Europe.This drought-sensitive species dominates even-aged stands as well more natural stands composed of a mixture of tree specie...Aims Beech(Fagus sylvatica L.)is an important species in natural and managed forests in Europe.This drought-sensitive species dominates even-aged stands as well more natural stands composed of a mixture of tree species,age and size classes.This study evaluates the extent that heterogeneity in spacing and tree diameter affect the seasonal availability and use of water.Methods Two stands were evaluated:(i)a heterogeneous forest remnant(NAT)with trees up to;300 years old,a mean top height of 28.4 m and a total of 733 stems ha1with stem diameters averaging 18 cm and(ii)an even-aged 80-year old stand(MAN),with a height of 25 m,and a total of 283 stems ha1 with diameters averaging 38 cm.Stem sap flow,Js(g m2 s1),was continuously measured in 12(MAN)and 13(NAT)trees using 20-mm long heat dissipation sensors.Individual tree measures of sap flow were correlated using non-linear statistical methods with air vapour pressure deficit(D,hPa)and global radiation(Rg,J m2 day1),along with constraints imposed by reductions in soil water content(SWC).SWC was measured as volumetric%using time domain reflectometry.Important Findings The daily integrated Js(Js-sum)for trees growing in the evenly spaced MAN stand and trees in canopy and closed forest positions in NAT stand decreased as the availability of soil moisture was reduced.In the heterogeneous NAT stand,SWC in a recently formed canopy gap remained high throughout the vegetation period.Based on regression models,the predicted relative decrease in Js-sum for dry relative to moist soil water conditions in the closed forest(at mean daily D=10 hPa)was 7–11%for trees near the gap and 39–42%for trees in the closed forest.In MAN,the reduction in Js-sum was 29%in dry relative to moist conditions.Js-sum in the outer 20 mm of the xylem in NAT was lower than that in MAN and the rate of decline in Js with xylem depth was less in NAT than in MAN.In MAN,Js-sum in deep and outer xylem was negatively affected at low soil moisture availability;in NAT,this was the case for only the outer展开更多
Gated transport measurements are the backbone of electrical characterization of nanoscale electronic devices. Scanning gate microscopy （SGM） is one such gating technique that adds crucial spatial information, access...Gated transport measurements are the backbone of electrical characterization of nanoscale electronic devices. Scanning gate microscopy （SGM） is one such gating technique that adds crucial spatial information, accessing the localized properties of semiconductor devices. Nanowires represent a central device concept due to the potential to combine very different materials. However, SGM on semiconductor nanowires has been limited to a resolution in the 50-100 nm range. Here, we present a study by SGM of newly developed III-V semiconductor nanowire InAs/GaSb heterojunction Esaki tunnel diode devices under ultra-high vacuum. Sub-5 nm resolution is demonstrated at room temperature via use of quartz resonator atomic force microscopy sensors, with the capability to resolve InAs nanowire facets, the InAs/GaSb tunnel diode transition and nanoscale defects on the device. We demonstrate that such measurements can rapidly give important insight into the device properties via use of a simplified physical model, without the requirement for extensive calculation of the electrostatics of the system. Interestingly, by precise spatial correlation of the device electrical transport properties and surface structure we show the position and existence of a very abrupt （〈10 nm） electrical transition across the InAs/GaSb junction despite the change in material composition occurring only over 30-50 nm. The direct and simultaneous link between nanostructure composition and electrical properties helps set important limits for the precision in structural control needed to achieve desired device performance.展开更多
In-air epitaxy of nanostructures(Aerotaxy)has recently emerged as a viable route for fast,large-scale production.In this study,we use small-a ngle X-ray scatteri ng to perform direct in-flight characterizati ons of th...In-air epitaxy of nanostructures(Aerotaxy)has recently emerged as a viable route for fast,large-scale production.In this study,we use small-a ngle X-ray scatteri ng to perform direct in-flight characterizati ons of the first step of this process,i.e.,the en gineered formatio n of Au and Pt aerosol nan oparticles by spark gen erati on in a flow of N2 gas.This represe nts a particular challe nge for characterizati on because the particle density can be extremely low in con trolled production.The particles produced are exami ned duri ng producti on at operatio nal pressures close to atmospheric conditions and exhibit a log no rmal size distributi on ranging from 5-100nm.The Au and Pt particle productio n and detection are compared.We observe and characterize the nanoparticles at different stages of synthesis and extract the corresponding domi nant physical properties,in cludi ng the average particle diameter and sphericity,as in flue need by particle sintering and the prese nee of aggregates.We observe highly sorted and sin tered spherical Au nano particles at ultra-dilute concen tratio ns(<5×10^5 particles/cm^3)corresponding to a volume fraction below 3×10^-10,which is orders of magnitude below that of previously measured aerosols.We independently confirm an average particle radius of 25 nm via Guinier and Kratky plot analysis.Our study indicates that with high-intensity synchrotron beams and careful con sideratio n of backgro und removal,size and shape info rmati on can be obtai ned for extremely low particle concentrations with industrially relevant narrow size distributions.展开更多
读者阅读本文时,已经为迎接新的世纪、新的千年的到来而举起过酒杯、燃放过鞭炮、敲响过钟声。本文告诉你:世界上还有不少人认为,新的世纪,新的千年应该始于2001年的元旦!因此,你可能要再庆祝一次: According to the Gregorian(阳历)cal...读者阅读本文时,已经为迎接新的世纪、新的千年的到来而举起过酒杯、燃放过鞭炮、敲响过钟声。本文告诉你:世界上还有不少人认为,新的世纪,新的千年应该始于2001年的元旦!因此,你可能要再庆祝一次: According to the Gregorian(阳历)calendar, which begins the Christian era at year 1 A. D., the third millennium does not begin until 2001.(注意句中的not…until) 因此,美国总统克林顿就曾幽默地说道: Maybe I can do it twice, and I'll be the president of two millennial changes. 克林顿的这次讲话敞开了自己的心扉,说了心里话: Clinton has frequently spoken of his desire to be remembered as a president who prepared the United States for the 21st century. 虽然离下台的日子还远,但是,他已有心理准备。 而下面这句话则表白了他的敬业心,句中的3个parallelisms用得很精彩: I am acutely mindful of the fact that I have 14 months left, and that I need to be out there squeezing the most out of every day and that I need to get as much done as I can for the American people. 最后,下句中的副词值得我们记学: I'm dead serious about it.】展开更多
The COST Action FP0903 “Climate Change and Forest Mitigation and Adaptation in a Polluted Environment (MAFor)” involved 29 countries and created a platform for information exchange with experts from different fields...The COST Action FP0903 “Climate Change and Forest Mitigation and Adaptation in a Polluted Environment (MAFor)” involved 29 countries and created a platform for information exchange with experts from different fields, with the following main objectives: 1) to increase understanding of the state and potential of forest mitigation and adaptation to climate change in a polluted environment and 2) to reconcile process-oriented research, long-term monitoring and applied modelling at comprehensive forest research sites. In particular, MAFor translated the existing European knowledge on climate and air pollution dynamics into prospects for forest research and monitoring, with focus on the carbon, ozone, nitrogen and water budgets. The aim of this paper is to summarize scientific activities and achievements of MAFor: the creation of a meta-database for highlighting the available data and integrating the information from European forest research/monitoring networks;the development of a new concept of forest sites for research and monitoring (Supersites);the identification of the main knowledge gaps;and the definition of priorities for forest adaptation to climate change in a polluted environment. The action also increased European capacity building in this sector by organizing five conferences, granting 64 short-term scientific missions, organizing four training schools and publishing more than 100 papers.展开更多
Background: Previous studies showed that blood pressure was reduced in patients with chronic renal failure during hemodialysis with glucose added to the dialysis fluid. We wanted to test the hypotheses that blood pres...Background: Previous studies showed that blood pressure was reduced in patients with chronic renal failure during hemodialysis with glucose added to the dialysis fluid. We wanted to test the hypotheses that blood pressure is reduced in non-diabetic and diabetic dialysis patients, when glucose is added to the dialysis fluid, and that blood pressure changes are caused by changes in plasma concentrations of vasoactive hormones or to vasodilation secondary to an increase in body temperature. Methods: The effect of dialysis with glucose added to the dialysis fluid was measured in three randomized, placebo-controlled, un-blinded and cross-over studies with periods of one week duration. In non-diabetic nephropathy (Study 1, n = 19) and diabetic nephropathy (Study 2, n = 15), we measured blood pressure (BP) and pulse rate (PR), plasma concentrations of glucose (p-Glucose), renin (PRC), angiotensin II (p-AngII), endothelin (p-Endot), insulin (p-Ins), glucagon (p-Glu), and human growth hormone (p-hGH). In non-diabetic nephropathy (Study 3, n = 24), we measured the effect of dialysis with glucose added to the dialysis fluid on energy transport from form the body using body temperature control. Results: Study 1 and 2 showed that BP, PRC, p-AngII, and p-Ins were unchanged, whereas P-Endot increased and P-hGH decreased, in dialysis patients with or without glucose added to the dialysis fluid. In diabetics, a marginal increase in p-Glu was measured during dialysis with glucose, but not without glucose. Study 3 showed that SBP increased significantly using dialysis with temperature control of dialysis fluid compared with no temperature control (145 versus 138 mm Hg). In parallel with the increase in SBP, the energy flux from the patients was significantly higher with temperature control than without. Conclusion: In non-diabetics and diabetics, blood pressure was unchanged during dialysis with glucose added to the dialysis fluid in a short-term study. Vasoactive hormones in plasma were changed in the same way independently of glu展开更多
This paper presents an attempt to develop a new system for fixing carbon dioxide from the atmosphere.The proposed molecular system has been designed to have the capacity to spontaneously bind CO_(2)from the atmosphere...This paper presents an attempt to develop a new system for fixing carbon dioxide from the atmosphere.The proposed molecular system has been designed to have the capacity to spontaneously bind CO_(2)from the atmosphere with high affinity.The molecular system is furthermore designed to have the ability to liberate CO_(2)at a later stage in the process,i.e.,in a separate compartment.The liberated CO_(2)presents a carbon neutral way of obtaining pure CO_(2).The proposed molecular system is based on a small stable organic molecule that potentially have two forms:one without bound CO_(2)and one with bound CO_(2).One class of molecules that undergo a reaction compatible with our purposal is the merocyanine dyes that exhibit photochromic properties.Based on this structural class of molecules,a system for the potential fixing of CO_(2)has been developed.展开更多
基金BW gratefully acknowledges receipt of funding from the Australian Research Council through the Centre of Excellence in Plant Cell walls
文摘This review describes dietary fibres originating from a range of foods,particularly in relation to their plant cell walls.It explores the categorization of dietary fibres into "soluble" or "insoluble".It also emphasizes dietary fibre fermentability,in terms of describing how the gastro-intestinal tract(GIT) microbiota respond to a selection of fibres from these categories.Food is categorized into cereals,legumes,fruits and vegetables.Mention is also made of example whole foods and why differences in physico-chemical characteristics between "purified" and "non-purified"food components are important in terms of health.Lastly,recommendations are made as to how dietary fibre could be classified differently,in relation to its functionality in terms of fermentability,rather than only its solubility.
基金supported by grants from the National Institutes of Health (NIH) [No. K25CA129173 (MMA), R01CA122031 (ASA), and 1R01CA160216 (ASA)]
文摘Tumor cell proliferation, infiltration, migration, and neovascularization are known causes of treatment resistance in glioblastoma multiforme(GBM). The purpose of this study was to determine the effect of radiation on the growth characteristics of primary human GBM developed in a nude rat. Primary GBM cells grown from explanted GBM tissues were implanted orthotopically in nude rats. Tumor growth was confirmed by magnetic resonance imaging on day 77(baseline) after implantation. The rats underwent irradiation to a dose of 50 Gy delivered subcuratively on day 84 postimplantation(n = 8), or underwent no radiation(n = 8). Brain tissues were obtained on day 112(nonirradiated) or day 133(irradiated). Immunohistochemistry was performed to determine tumor cell proliferation(Ki-67) and to assess the expression of infiltration marker(matrix metalloproteinase-2, MMP-2) and cell migration marker(CD44). Tumor neovascularization was assessed by microvessel density using von-Willebrand factor(vWF) staining. Magnetic resonance imaging showed well-developed, infiltrative tumors in 11 weeks postimplantation. The proportion of Ki-67-positive cells in tumors undergoing radiation was(71 ± 15)% compared with(25 ± 12)% in the nonirradiated group(P = 0.02). The number of MMP-2-positive areas and proportion of CD44-positive cells were also high in tumors receiving radiation, indicating great invasion and infiltration. Microvessel density analysis did not show a significant difference between nonirradiated and irradiated tumors. Taken together, we found that subcurative radiation significantly increased proliferation, invasion, and migration of primary GBM. Our study provides insights into possible mechanisms of treatment resistance following radiation therapy for GBM.
文摘Purpose:This article investigates the role of private supplementary tutoring in Denmark in light of the country’s pedagogical traditions in schools and leisure spheres.Design/Approach/Methods:Although tutoring activities are increasing,the phenomenon is not as prevalent in Denmark as in many other countries.In this article,we look into the history of Danish pedagogy for answers as to why this is the case.In the analytical sections of the article,we include research on parental values of child-rearing,as well as findings from a pilot study on Danish families purchasing private supplementary tutoring,the public debate about private tutoring,and contemporary youth research.Findings:With a solid emphasis on democracy and equality in Danish pedagogy,the conditions for increasing private supplementary tutoring in Denmark have been challenged.However,a current focus on global competition,formal competencies,and higher academic performance among children and young people suggests that providers of private tutoring perhaps face a brighter future—also in Denmark.Originality/Value:This article addresses a new field of qualitative research on private supplementary tutoring in Denmark and may be a platform for further reflection and empirical research.
文摘Epidemiological studies have demonstrated reduced risk of developing cancer upon consumption of diets rich in cruciferous vegetables. This chemoprevention has been largely attributed to the presence of the natural products glu- cosinolates, particularly the methionine-derived glucoraphanin from broccoli. Improved nutrition by functional foods or health-promoting dietary supplements is an attractive means for prevention of lifestyle-based diseases. Towards this goal, we have engineered the glucoraphanin pathway into tobacco. First, we engineered elongation of the side chain of methionine to produce the key intermediate dihomo-methionine. This process is catalyzed through two cycles in a chain-elongation pathway that takes place partly in the cytosol and partly in the chloroplast. Second, by coupling the five enzymes of the chain-elongation pathway to eight enzymes of the glucosinolate pathway, we show production of glucoraphanin together with other glucosinolates derived from chain-elongated isoleucine and/or leucine. The conver- sion of methionine to glucoraphanin is obtained via 14 intermediates. Demonstrating the production of the high-value glucoraphanin in a heterologous host has great potential in the food and medicinal industry as a means to generate a stable, rich source of glucoraphanin for the benefit of human health.
文摘Nitrogen oxides (NO<sub>x</sub>) in urban air close to ground have significant health implications. Restrictions in traffic, mandatory use of catalytic converters on vehicles, and novel photocatalytic coatings on surfaces contribute to reducing the level of NO<sub>x</sub> in cities. The aim of this study is to establish environmental profiles of NO<sub>x</sub> removal by a Three-Way Catalyst (TWC) car converter and by a photocatalytic surface coating (for asphalt and concrete pavements) for fostering technological development in reducing the levels of NO<sub>x</sub> in urban air. We assessed the environmental performance for the removal of 1 kg NO<sub>x</sub> by the two technologies with Life Cycle Assessment (LCA;EF.3 impact assessment method). In order to do so, we established Life-Cycle-Inventory (LCI) data representing production, operation and end-of-life of the two technologies based on data from literature and industry. The production of photocatalytic surface coatings, used on concrete and asphalt, has environmental loads two orders of magnitude lower than the environmental benefits of NO<sub>x</sub> reduction expressed as a reduction in Photochemical Ozone Formation (POF), Acidification (A), and Terrestrial Eutrophication (TE). The vehicle catalytic converter shows similar results except that the use of rare earth elements in the production constitutes a significant load to Freshwater Ecotoxicity (FET) and that additional use of fuel during operation induces a modest Climate Change (CC) impact. For both technologies, the environmental benefits of reducing NO<sub>x</sub> far exceed any adverse environmental aspects of the production of the technologies.
文摘Aims Beech(Fagus sylvatica L.)is an important species in natural and managed forests in Europe.This drought-sensitive species dominates even-aged stands as well more natural stands composed of a mixture of tree species,age and size classes.This study evaluates the extent that heterogeneity in spacing and tree diameter affect the seasonal availability and use of water.Methods Two stands were evaluated:(i)a heterogeneous forest remnant(NAT)with trees up to;300 years old,a mean top height of 28.4 m and a total of 733 stems ha1with stem diameters averaging 18 cm and(ii)an even-aged 80-year old stand(MAN),with a height of 25 m,and a total of 283 stems ha1 with diameters averaging 38 cm.Stem sap flow,Js(g m2 s1),was continuously measured in 12(MAN)and 13(NAT)trees using 20-mm long heat dissipation sensors.Individual tree measures of sap flow were correlated using non-linear statistical methods with air vapour pressure deficit(D,hPa)and global radiation(Rg,J m2 day1),along with constraints imposed by reductions in soil water content(SWC).SWC was measured as volumetric%using time domain reflectometry.Important Findings The daily integrated Js(Js-sum)for trees growing in the evenly spaced MAN stand and trees in canopy and closed forest positions in NAT stand decreased as the availability of soil moisture was reduced.In the heterogeneous NAT stand,SWC in a recently formed canopy gap remained high throughout the vegetation period.Based on regression models,the predicted relative decrease in Js-sum for dry relative to moist soil water conditions in the closed forest(at mean daily D=10 hPa)was 7–11%for trees near the gap and 39–42%for trees in the closed forest.In MAN,the reduction in Js-sum was 29%in dry relative to moist conditions.Js-sum in the outer 20 mm of the xylem in NAT was lower than that in MAN and the rate of decline in Js with xylem depth was less in NAT than in MAN.In MAN,Js-sum in deep and outer xylem was negatively affected at low soil moisture availability;in NAT,this was the case for only the outer
文摘Gated transport measurements are the backbone of electrical characterization of nanoscale electronic devices. Scanning gate microscopy （SGM） is one such gating technique that adds crucial spatial information, accessing the localized properties of semiconductor devices. Nanowires represent a central device concept due to the potential to combine very different materials. However, SGM on semiconductor nanowires has been limited to a resolution in the 50-100 nm range. Here, we present a study by SGM of newly developed III-V semiconductor nanowire InAs/GaSb heterojunction Esaki tunnel diode devices under ultra-high vacuum. Sub-5 nm resolution is demonstrated at room temperature via use of quartz resonator atomic force microscopy sensors, with the capability to resolve InAs nanowire facets, the InAs/GaSb tunnel diode transition and nanoscale defects on the device. We demonstrate that such measurements can rapidly give important insight into the device properties via use of a simplified physical model, without the requirement for extensive calculation of the electrostatics of the system. Interestingly, by precise spatial correlation of the device electrical transport properties and surface structure we show the position and existence of a very abrupt （〈10 nm） electrical transition across the InAs/GaSb junction despite the change in material composition occurring only over 30-50 nm. The direct and simultaneous link between nanostructure composition and electrical properties helps set important limits for the precision in structural control needed to achieve desired device performance.
文摘In-air epitaxy of nanostructures(Aerotaxy)has recently emerged as a viable route for fast,large-scale production.In this study,we use small-a ngle X-ray scatteri ng to perform direct in-flight characterizati ons of the first step of this process,i.e.,the en gineered formatio n of Au and Pt aerosol nan oparticles by spark gen erati on in a flow of N2 gas.This represe nts a particular challe nge for characterizati on because the particle density can be extremely low in con trolled production.The particles produced are exami ned duri ng producti on at operatio nal pressures close to atmospheric conditions and exhibit a log no rmal size distributi on ranging from 5-100nm.The Au and Pt particle productio n and detection are compared.We observe and characterize the nanoparticles at different stages of synthesis and extract the corresponding domi nant physical properties,in cludi ng the average particle diameter and sphericity,as in flue need by particle sintering and the prese nee of aggregates.We observe highly sorted and sin tered spherical Au nano particles at ultra-dilute concen tratio ns(<5×10^5 particles/cm^3)corresponding to a volume fraction below 3×10^-10,which is orders of magnitude below that of previously measured aerosols.We independently confirm an average particle radius of 25 nm via Guinier and Kratky plot analysis.Our study indicates that with high-intensity synchrotron beams and careful con sideratio n of backgro und removal,size and shape info rmati on can be obtai ned for extremely low particle concentrations with industrially relevant narrow size distributions.
文摘读者阅读本文时,已经为迎接新的世纪、新的千年的到来而举起过酒杯、燃放过鞭炮、敲响过钟声。本文告诉你:世界上还有不少人认为,新的世纪,新的千年应该始于2001年的元旦!因此,你可能要再庆祝一次: According to the Gregorian(阳历)calendar, which begins the Christian era at year 1 A. D., the third millennium does not begin until 2001.(注意句中的not…until) 因此,美国总统克林顿就曾幽默地说道: Maybe I can do it twice, and I'll be the president of two millennial changes. 克林顿的这次讲话敞开了自己的心扉,说了心里话: Clinton has frequently spoken of his desire to be remembered as a president who prepared the United States for the 21st century. 虽然离下台的日子还远,但是,他已有心理准备。 而下面这句话则表白了他的敬业心,句中的3个parallelisms用得很精彩: I am acutely mindful of the fact that I have 14 months left, and that I need to be out there squeezing the most out of every day and that I need to get as much done as I can for the American people. 最后,下句中的副词值得我们记学: I'm dead serious about it.】
基金Support by the COST Action FP0903“Climate change and forest mitigation and adaptation in the polluted environment”
文摘The COST Action FP0903 “Climate Change and Forest Mitigation and Adaptation in a Polluted Environment (MAFor)” involved 29 countries and created a platform for information exchange with experts from different fields, with the following main objectives: 1) to increase understanding of the state and potential of forest mitigation and adaptation to climate change in a polluted environment and 2) to reconcile process-oriented research, long-term monitoring and applied modelling at comprehensive forest research sites. In particular, MAFor translated the existing European knowledge on climate and air pollution dynamics into prospects for forest research and monitoring, with focus on the carbon, ozone, nitrogen and water budgets. The aim of this paper is to summarize scientific activities and achievements of MAFor: the creation of a meta-database for highlighting the available data and integrating the information from European forest research/monitoring networks;the development of a new concept of forest sites for research and monitoring (Supersites);the identification of the main knowledge gaps;and the definition of priorities for forest adaptation to climate change in a polluted environment. The action also increased European capacity building in this sector by organizing five conferences, granting 64 short-term scientific missions, organizing four training schools and publishing more than 100 papers.
文摘Background: Previous studies showed that blood pressure was reduced in patients with chronic renal failure during hemodialysis with glucose added to the dialysis fluid. We wanted to test the hypotheses that blood pressure is reduced in non-diabetic and diabetic dialysis patients, when glucose is added to the dialysis fluid, and that blood pressure changes are caused by changes in plasma concentrations of vasoactive hormones or to vasodilation secondary to an increase in body temperature. Methods: The effect of dialysis with glucose added to the dialysis fluid was measured in three randomized, placebo-controlled, un-blinded and cross-over studies with periods of one week duration. In non-diabetic nephropathy (Study 1, n = 19) and diabetic nephropathy (Study 2, n = 15), we measured blood pressure (BP) and pulse rate (PR), plasma concentrations of glucose (p-Glucose), renin (PRC), angiotensin II (p-AngII), endothelin (p-Endot), insulin (p-Ins), glucagon (p-Glu), and human growth hormone (p-hGH). In non-diabetic nephropathy (Study 3, n = 24), we measured the effect of dialysis with glucose added to the dialysis fluid on energy transport from form the body using body temperature control. Results: Study 1 and 2 showed that BP, PRC, p-AngII, and p-Ins were unchanged, whereas P-Endot increased and P-hGH decreased, in dialysis patients with or without glucose added to the dialysis fluid. In diabetics, a marginal increase in p-Glu was measured during dialysis with glucose, but not without glucose. Study 3 showed that SBP increased significantly using dialysis with temperature control of dialysis fluid compared with no temperature control (145 versus 138 mm Hg). In parallel with the increase in SBP, the energy flux from the patients was significantly higher with temperature control than without. Conclusion: In non-diabetics and diabetics, blood pressure was unchanged during dialysis with glucose added to the dialysis fluid in a short-term study. Vasoactive hormones in plasma were changed in the same way independently of glu
基金supported by the Danish Research Council for Technology and Production Sciences(FTP 274-05-0356).
文摘This paper presents an attempt to develop a new system for fixing carbon dioxide from the atmosphere.The proposed molecular system has been designed to have the capacity to spontaneously bind CO_(2)from the atmosphere with high affinity.The molecular system is furthermore designed to have the ability to liberate CO_(2)at a later stage in the process,i.e.,in a separate compartment.The liberated CO_(2)presents a carbon neutral way of obtaining pure CO_(2).The proposed molecular system is based on a small stable organic molecule that potentially have two forms:one without bound CO_(2)and one with bound CO_(2).One class of molecules that undergo a reaction compatible with our purposal is the merocyanine dyes that exhibit photochromic properties.Based on this structural class of molecules,a system for the potential fixing of CO_(2)has been developed.
