Laser-induced breakdown spectroscopy （LIBS） was used to decipher the unique multi-elemental characteristics of Juncus effusus L. The spectral fingerprints of Juncus effusus L. were established based on elemental mic...Laser-induced breakdown spectroscopy （LIBS） was used to decipher the unique multi-elemental characteristics of Juncus effusus L. The spectral fingerprints of Juncus effusus L. were established based on elemental microanalysis via LIBS. Microanalysis and multimode sampling methodologies were designed in this study. The relative standard deviation （RSD） approach was performed to optimize the multi-shot measurements. Taking advantage of the capability with no or minimal sample pre-treatment of LIBS, a thermodynamic chart of four elements （Mg, Ca, Ba, and Na） was created from twelve collection regions. The diagram of elemental distribution on a micro-scale was generated to explore the nature of Juncus effusus L. by LIBS. The results demon- strated that LIBS is a promising technique for rapid elemental microanalysis of heterogeneous samples.展开更多
The Andean region of Ecuador is characterized by extreme poverty caused by low agricultural productivity, limited off-farm opportunities, and lack of access to markets. Poverty is related to degradation of natural res...The Andean region of Ecuador is characterized by extreme poverty caused by low agricultural productivity, limited off-farm opportunities, and lack of access to markets. Poverty is related to degradation of natural resources as lagging agricultural productivity leads to incursions into fragile areas and use of erosive farming techniques on steeply sloped hillsides. Food production in fragile areas degrades soil and water resources, contributes to deforestation and loss of biodiversity, and reduces productive potential over time. This article discusses an agricultural development project designed to reduce the long-term downward development spiral in a watershed in Bolivar, Ecuador. The applied research program began with analysis of the state of soil resources, water, and biodiversity in the Chimbo sub-watershed. This information was used to design a plan with the input of local stakeholders to introduce environmentally friendly farming practices, soil and water conservation techniques, and various institutional innovations to promote resource conservation. This adaptive management program has been a solid success. This article describes the project, the challenges it faced, and how the process of adaptive management led to consensus among stakeholders about the appropriateness of sustainable management practices. We show how implementation of enhanced management practices contribute to reduced environmental vulnerability and improved welfare.展开更多
This research explores the transport of a Jeffrey fluid through a permeable slit of microchannel under the effect of a porous medium and constant reabsorption.Physical laws of fluid mechanics are used to study the flo...This research explores the transport of a Jeffrey fluid through a permeable slit of microchannel under the effect of a porous medium and constant reabsorption.Physical laws of fluid mechanics are used to study the flow in a cross-sectional area of a narrow slit which generates a highly nonlinear system of partial differential equation with nonhomogeneous boundary conditions.To solve the complex boundary value problem;a recursive(Langlois)approach is used and explicit expressions for velocity,pressure,stream function,flux,shear stress and fractional reabsorption are calculated.It is noticed that the flow rate at the centre line of slit and shear stress on the walls of slit decay due to the presence of porous medium and viscoelastic fluid parameters.It is also quantitatively observed that more pressure is required for the fluid flow when the slit is filled with a porous medium and reabsorption on the walls is constant.The mathematical results of the present research have significant importance in the field of biofluid mechanics and medical industry,therefore the application of a diseased rat kidney is also included in this research:and reabsorption velocities in the case of a diseased and a healthy rat kidney are calculated with the effects of a porous medium and constant re-absorption.展开更多
基金supported by National Natural Science Foundation of China(No.81303218)Beijing Municipal Government for the University Affiliated with the Party Central CommitteeDoctoral Fund of Ministry of Education of China(No.20130013120006)
文摘Laser-induced breakdown spectroscopy （LIBS） was used to decipher the unique multi-elemental characteristics of Juncus effusus L. The spectral fingerprints of Juncus effusus L. were established based on elemental microanalysis via LIBS. Microanalysis and multimode sampling methodologies were designed in this study. The relative standard deviation （RSD） approach was performed to optimize the multi-shot measurements. Taking advantage of the capability with no or minimal sample pre-treatment of LIBS, a thermodynamic chart of four elements （Mg, Ca, Ba, and Na） was created from twelve collection regions. The diagram of elemental distribution on a micro-scale was generated to explore the nature of Juncus effusus L. by LIBS. The results demon- strated that LIBS is a promising technique for rapid elemental microanalysis of heterogeneous samples.
文摘The Andean region of Ecuador is characterized by extreme poverty caused by low agricultural productivity, limited off-farm opportunities, and lack of access to markets. Poverty is related to degradation of natural resources as lagging agricultural productivity leads to incursions into fragile areas and use of erosive farming techniques on steeply sloped hillsides. Food production in fragile areas degrades soil and water resources, contributes to deforestation and loss of biodiversity, and reduces productive potential over time. This article discusses an agricultural development project designed to reduce the long-term downward development spiral in a watershed in Bolivar, Ecuador. The applied research program began with analysis of the state of soil resources, water, and biodiversity in the Chimbo sub-watershed. This information was used to design a plan with the input of local stakeholders to introduce environmentally friendly farming practices, soil and water conservation techniques, and various institutional innovations to promote resource conservation. This adaptive management program has been a solid success. This article describes the project, the challenges it faced, and how the process of adaptive management led to consensus among stakeholders about the appropriateness of sustainable management practices. We show how implementation of enhanced management practices contribute to reduced environmental vulnerability and improved welfare.
文摘This research explores the transport of a Jeffrey fluid through a permeable slit of microchannel under the effect of a porous medium and constant reabsorption.Physical laws of fluid mechanics are used to study the flow in a cross-sectional area of a narrow slit which generates a highly nonlinear system of partial differential equation with nonhomogeneous boundary conditions.To solve the complex boundary value problem;a recursive(Langlois)approach is used and explicit expressions for velocity,pressure,stream function,flux,shear stress and fractional reabsorption are calculated.It is noticed that the flow rate at the centre line of slit and shear stress on the walls of slit decay due to the presence of porous medium and viscoelastic fluid parameters.It is also quantitatively observed that more pressure is required for the fluid flow when the slit is filled with a porous medium and reabsorption on the walls is constant.The mathematical results of the present research have significant importance in the field of biofluid mechanics and medical industry,therefore the application of a diseased rat kidney is also included in this research:and reabsorption velocities in the case of a diseased and a healthy rat kidney are calculated with the effects of a porous medium and constant re-absorption.
