The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
T Hernandez - One of the best experts on this subject based on the ideXlab platform.
-
severe drought conditions modify the microbial community Structure Size and activity in amended and unamended soils
Soil Biology & Biochemistry, 2012Co-Authors: S Hueso, C Garcia, T HernandezAbstract:Abstract Biological activity could be affected severely by the impact on soil quality of drought, which can be very severe in Southern areas of Europe. The objective of this work was to assess, under controlled laboratory conditions, whether a long period of severe drought (six months) can affect the Structure, Size and activity of the microbial community of a semiarid soil, as well as the influence of organic amendments on these effects. The soil was incubated for 180 days under controlled conditions (25 °C and 60/80% day/night relative humidity), with two treatments: unamended (US) and amended (AS) with manure compost (100 t ha−1). Two levels of irrigation were imposed: (1) well-watered (MUS and MAS), the soil being maintained at 60% of its water-holding capacity (WHC), and (2) dry soils, without irrigation (DUS and DAS). The drought conditions caused a significant inhibition of C and N mineralisation, and affected negatively the Size and activity of the soil microbial biomass. Thus, after 180 days under drought conditions, the non-watered soils showed higher organic carbon content than the well-watered soils. Likewise, the stressed soils showed significantly lower values of water-soluble N, ATP content, microbial biomass C, alkaline phosphomonoesterase activity and total functional diversity than the well-watered soils. There was a significant decrease in the total amount of each fatty acid in DUS and DAS with respect to MUS and MAS after 180 days under drought. The physiology of the microbial community was affected more strongly by water stress than was the microbial community Structure, changes in the Structure caused by drought being less pronounced in amended than in unamended soils. Furthermore, the organic amendments increased the soil organic matter content, hence improving the Size and activity of the soil microbial biomass and helping soil to retain moisture.
-
application of fresh and composted organic wastes modifies Structure Size and activity of soil microbial community under semiarid climate
Applied Soil Ecology, 2008Co-Authors: Felipe Bastida, C Garcia, Ellen Kandeler, Jose L Moreno, T HernandezAbstract:Abstract Although the application of organic amendments is considered a suitable tool for improving soil fertility, few studies have been conducted in semiarid climates to evaluate the joint effect of such practice on the Structure and function of the soil's microbial community. The aim of this work therefore was to make a comparative study of the effect of organic materials of differing degrees of stabilization (a sewage sludge and a compost made from the same) on the Size, activity and Structure of the microbial community in a semiarid soil. In samples taken in spring, summer and autumn over a 2-year period we analysed parameters that indicate the Size of the microbial community [microbial biomass C (MBC)], its general activity (ATP and respiration) and specific activity related to the N, P and C cycles in the soil (urease, phosphatase and β-glucosidase, respectively). Two years after the organic amendment, the Structure of the microbial community was studied by analysing phospholipid fatty acids (PLFAs). At the end of the experiment, the MBC of the compost and sludge-treated soils was 489 and 463 mg C mic kg −1 , respectively, while the MBC of the control soils was 247 mg C mic kg −1 . Over the 2-year period, the higher β-glucosidase, urease and alkaline phosphatase activities of compost and sludge-treated soils reflected higher substrate availability in these plots compared to the control plots. Indeed, plant abundance increased by about 25% with organic amendments. Whereas the bacterial to fungal ratio of signature PLFAs did not change, the ratio of monounsaturated/saturated and the ratio of Gram + /Gram − of the different treatments indicated that a different bacterial community developed 2 years after amendment with compost and sludge. Thus, factor analysis via PLFAs showed a change in microbial community Structure in amended soils versus control soil. It can be concluded that microbial biomass and activity of degraded semiarid soils can be improved by the addition of organic materials of differing degrees of stabilization (compost and sewage sludge). Compost-amended soils showed the highest carbon contents, while in general no differences in activity or microbial biomass where found between compost or sludge treatments. Although phytotoxic substances in sewage sludge might negatively affect plant development, the similar density of plant cover developed in sludge and compost-treated soils suggests that any phytotoxic substances had been degraded.
Xueyan Zhao - One of the best experts on this subject based on the ideXlab platform.
-
Study of the Structure Size interval of incomplete geometrically similitude model of the elastic thin plates
2020Co-Authors: You Wang, Xueyan ZhaoAbstract:To design the similitude test model having the same nature characteristics with the prototype of the elastic thin plates, an innovative method of confirm the Structure Size applicable interval of distorted (incomplete geometrically) similar model was proposed. Firstly, the complete scaling laws and the distortion scaling laws between the model and its prototype were established by using the governing equation analysis. Then, under the study of the Structure Size applicable interval which kept the same first-order nature characteristic (nature frequency and vibration mode), through the research of the vibration mode control interval (each order of the mode keep the same) and the predict interval of frequency, the method of Structure Size applicable interval of distorted similar model was obtained, which they were in different orders with the same nature characteristic. Finally, the proposed calculation method is verified by experiment.
-
determination method of dynamic distorted scaling laws and applicable Structure Size intervals of a rotating thin wall short cylindrical shell
Proceedings of the Institution of Mechanical Engineers Part C: Journal of Mechanical Engineering Science, 2015Co-Authors: Xueyan Zhao, Deyou WangAbstract:This study investigates the applicability of distortion models for predicting dynamic characteristics of a rotating thin-wall short cylindrical shell. The significance of this study is that it provides a necessary scaling law, applicable Structure Size intervals, and its boundary functions, which can guide the design of distortion models. Sensitivity analysis and governing equations are employed to establish the scaling law between the model and the prototype. Then a commonly used 7050 aluminum alloy cylindrical shell is analyzed as a prototype. The determination of applicable Structure Size intervals is discussed, and the boundary functions of the applicable Structure Size intervals are investigated. The applicability of the scaling law and the applicable intervals of rotating thin-wall short cylindrical shell are verified numerically. The results indicate that distortion models that satisfy the Structure Size applicable intervals can predict the characteristics of the prototype with good accuracy.
-
Determination method of the Structure Size interval of dynamically similar models for predicting vibration characteristics of the coated thin plates
Proceedings of the Institution of Mechanical Engineers Part C: Journal of Mechanical Engineering Science, 2014Co-Authors: Xueyan ZhaoAbstract:This study investigates the applicability of distorted models in predicting the frequencies and responses of coated thin plates. The significance of this study is that it provides the necessary scaling laws and Structure Size applicable intervals, which guide the design of distorted models. By comparing the effect of different coating thickness and different coating forms (single-sided coating and double-sided coatings), the direct use of a governing equation is employed to establish the scaling laws between the model and the prototype. Both complete and partial similarity is discussed. Then an aluminum-coated steel plate, which is commonly used, is analyzed as an example. Establishment of the Structure Size applicable interval is discussed, which should keep the same first-order natural characteristics (natural frequency and vibration mode). Applicable intervals of the distorted model under different orders are also obtained by using a numerical method. The applicability of the scaling laws and applicabl...
-
Determination method of the Structure Size interval of dynamic similar models for predicting vibration characteristics of the isotropic sandwich plates
Journal of Vibroengineering, 2014Co-Authors: Xueyan Zhao, Jianzhang LiAbstract:A method is studied for determining the Structure Size interval of dynamic similar models of the isotropic sandwich plates. Firstly, a comparison between the two theories of plates, the Resineer theory and the Hoff theory, is conducted, including their governing equations and the ANSYS analytic solutions of frequency. The Resineer theory is chosen as the basic theory of this paper finally. Secondly, the scaling laws between the model and prototype of isotropic sandwich plate are established by combining the dimensional analysis and governing analysis. Both complete and incomplete geometric similarity conditions are discussed. Thirdly, the determination method of the Structure Size interval of the models is proposed. The nature vibration mode keeps the same and the nature frequency and harmonic response keep in proportion with the prototype of the sandwich plate. At last, the flow step of the intervals determination method is given.
C Garcia - One of the best experts on this subject based on the ideXlab platform.
-
severe drought conditions modify the microbial community Structure Size and activity in amended and unamended soils
Soil Biology & Biochemistry, 2012Co-Authors: S Hueso, C Garcia, T HernandezAbstract:Abstract Biological activity could be affected severely by the impact on soil quality of drought, which can be very severe in Southern areas of Europe. The objective of this work was to assess, under controlled laboratory conditions, whether a long period of severe drought (six months) can affect the Structure, Size and activity of the microbial community of a semiarid soil, as well as the influence of organic amendments on these effects. The soil was incubated for 180 days under controlled conditions (25 °C and 60/80% day/night relative humidity), with two treatments: unamended (US) and amended (AS) with manure compost (100 t ha−1). Two levels of irrigation were imposed: (1) well-watered (MUS and MAS), the soil being maintained at 60% of its water-holding capacity (WHC), and (2) dry soils, without irrigation (DUS and DAS). The drought conditions caused a significant inhibition of C and N mineralisation, and affected negatively the Size and activity of the soil microbial biomass. Thus, after 180 days under drought conditions, the non-watered soils showed higher organic carbon content than the well-watered soils. Likewise, the stressed soils showed significantly lower values of water-soluble N, ATP content, microbial biomass C, alkaline phosphomonoesterase activity and total functional diversity than the well-watered soils. There was a significant decrease in the total amount of each fatty acid in DUS and DAS with respect to MUS and MAS after 180 days under drought. The physiology of the microbial community was affected more strongly by water stress than was the microbial community Structure, changes in the Structure caused by drought being less pronounced in amended than in unamended soils. Furthermore, the organic amendments increased the soil organic matter content, hence improving the Size and activity of the soil microbial biomass and helping soil to retain moisture.
-
application of fresh and composted organic wastes modifies Structure Size and activity of soil microbial community under semiarid climate
Applied Soil Ecology, 2008Co-Authors: Felipe Bastida, C Garcia, Ellen Kandeler, Jose L Moreno, T HernandezAbstract:Abstract Although the application of organic amendments is considered a suitable tool for improving soil fertility, few studies have been conducted in semiarid climates to evaluate the joint effect of such practice on the Structure and function of the soil's microbial community. The aim of this work therefore was to make a comparative study of the effect of organic materials of differing degrees of stabilization (a sewage sludge and a compost made from the same) on the Size, activity and Structure of the microbial community in a semiarid soil. In samples taken in spring, summer and autumn over a 2-year period we analysed parameters that indicate the Size of the microbial community [microbial biomass C (MBC)], its general activity (ATP and respiration) and specific activity related to the N, P and C cycles in the soil (urease, phosphatase and β-glucosidase, respectively). Two years after the organic amendment, the Structure of the microbial community was studied by analysing phospholipid fatty acids (PLFAs). At the end of the experiment, the MBC of the compost and sludge-treated soils was 489 and 463 mg C mic kg −1 , respectively, while the MBC of the control soils was 247 mg C mic kg −1 . Over the 2-year period, the higher β-glucosidase, urease and alkaline phosphatase activities of compost and sludge-treated soils reflected higher substrate availability in these plots compared to the control plots. Indeed, plant abundance increased by about 25% with organic amendments. Whereas the bacterial to fungal ratio of signature PLFAs did not change, the ratio of monounsaturated/saturated and the ratio of Gram + /Gram − of the different treatments indicated that a different bacterial community developed 2 years after amendment with compost and sludge. Thus, factor analysis via PLFAs showed a change in microbial community Structure in amended soils versus control soil. It can be concluded that microbial biomass and activity of degraded semiarid soils can be improved by the addition of organic materials of differing degrees of stabilization (compost and sewage sludge). Compost-amended soils showed the highest carbon contents, while in general no differences in activity or microbial biomass where found between compost or sludge treatments. Although phytotoxic substances in sewage sludge might negatively affect plant development, the similar density of plant cover developed in sludge and compost-treated soils suggests that any phytotoxic substances had been degraded.
L Lu - One of the best experts on this subject based on the ideXlab platform.
-
stress relaxation and the Structure Size dependence of plastic deformation in nanotwinned copper
Acta Materialia, 2009Co-Authors: L Lu, Yongfeng Shen, K Lu, S SureshAbstract:Stress-relaxation experiments were performed on nanotwinned Cu to characterize the twin Size-dependence of the activation volume and mobile dislocation density. We find that the variation of activation volume as a function of twin lamellae thickness can be captured well by a Hall–Petch-type relation. This Structure Size-dependence is interpreted to arise from a transition of the rate-controlling mechanism from intra-twin to twin boundary-mediated processes with decreasing twin thickness. Furthermore, we find that the exhaustion rate of mobile dislocations reduces with decreasing twin thickness. Such a twin Size-dependence is attributed to the increased strain-hardening rate associated with a high density of coherent twin boundaries. Our results demonstrate that twin boundary-mediated dislocation processes can effectively promote the strain hardening and preserve mobile dislocations, leading to ultrahigh strength while retaining ductility in nanotwinned Cu.
Matthias Kirschner - One of the best experts on this subject based on the ideXlab platform.
-
Bildverarbeitung für die Medizin - Structure Size Enhanced Histogram
Bildverarbeitung für die Medizin 2009, 2020Co-Authors: Stefan Wesarg, Matthias KirschnerAbstract:Direct volume visualization requires the definition of transfer functions (TFs) for the assignment of opacity and color. Multi-dimensional TFs are based on at least two image properties, and are specified by means of 2D histograms. In this work we propose a new type of a 2D histogram which combines gray value with information about the Size of the Structures. This Structure Size enhanced (SSE) histogram is an intuitive approach for representing anatomical features. Clinicians — the users we are focusing on — are much more familiar with selecting features by their Size than by their gradient magnitude value. As a proof of concept, we employ the SSE histogram for the definition of two-dimensional TFs for the visualization of 3D MRI and CT image data.
-
Structure Size Enhanced Histogram: A Transfer Function for 3D Volume Visualization
2020Co-Authors: Stefan Wesarg, Matthias KirschnerAbstract:Direct volume visualization requires the definition of transfer functions (TFs) for the assignment of opacity and color. Multi-dimentional TFs are based on at least two image properties, and are specified by means of 2D histograms. In this work we propose a new type of a 2D histogram which combines grey value with information about the Size of the Structures. This Structure Size Enhanced (SSE) histogram is an intuitive approach for representing anatomical features. Clinicians - the users we are focusing on - are much more familiar with selecting features by their Size than by their gradient magnitude value. As a proof of concept, we employ the SSE histogram for the definition of two-dimentional TFs for the visualization of 3D MRI and CT image data.
