1 Introduction Low-dimensional nanostructures, such as nanorods, nanowires, and nanotubes, have received much attention for their superior optical, electrical, catalytic and magnetic properties. Owing to their low di...1 Introduction Low-dimensional nanostructures, such as nanorods, nanowires, and nanotubes, have received much attention for their superior optical, electrical, catalytic and magnetic properties. Owing to their low dimensionality and quantum continement effect, low-dimensional nanoscale materials can be exploited as fundamental building blocks for nanoscience and nanodevices^[1-3]. In recent years, efforts have been devoted to develop new approaches to synthesize one-dimensional(lD) nanostructrued vanadium oxides or vanadates materials, such as V205, NaV2Os, and CuV206, which have been widely investigated in catalytic or electrochemical fields due to their outstanding structural flexibility^[4-6].展开更多
In the present study, bond-coats for thermal barrier coatings were deposited via air plasma spraying(APS) techniques onto Inconel 800 and Hastelloy C-276 alloy substrates. Scanning electron microscopy(SEM), transm...In the present study, bond-coats for thermal barrier coatings were deposited via air plasma spraying(APS) techniques onto Inconel 800 and Hastelloy C-276 alloy substrates. Scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), and atomic force microscopy(AFM) were used to investigate the phases and microstructure of the as-sprayed, APS-deposited Co Ni Cr Al Y bond-coatings. The aim of this work was to study the suitability of the bond-coat materials for high temperature applications. Confirmation of nanoscale grains of the γ/γ′-phase was obtained by TEM, high-resolution TEM, and AFM. We concluded that these changes result from the plastic deformation of the bond-coat during the deposition, resulting in Co Ni Cr Al Y bond-coatings with excellent thermal cyclic resistance suitable for use in high-temperature applications. Cyclic oxidative stability was observed to also depend on the underlying metallic alloy substrate.展开更多
Shelf-basin advection is essential to subsistence of the Arctic copepod Calanus hyperboreus population in high basin area. Its abundance, population structure and body size in pelagic layer were investigated with samp...Shelf-basin advection is essential to subsistence of the Arctic copepod Calanus hyperboreus population in high basin area. Its abundance, population structure and body size in pelagic layer were investigated with samples collected over a large range in the western Arctic Ocean during summer 2003, to evaluate the geographical variation in recruitment pattern. Calanus hyperboreus was absent from the shallow areas of the Chukchi Sea and most abundant in the slope area between the Chukchi Sea and Chukchi Abyssal Plain(CS-slope). Total abundance varied between 1 110.0 and 5 815.0 ind./m^2 in the CS-slope area and ranged from 40.0 to 950.0 ind./m^2 in the other areas. Early stages(CI–IV) dominated in the CS-slope area, whereas CV and adult females were frequently recorded only in deep basin areas. Geographical difference of prosome length was most evident in CIII,with average ranging from 2.48 to 2.61 mm at the CS-slope stations and 2.16–2.37 mm at the others. Abundance of early developmental stages(CI–CIV) correlated positively with Chl a concentration, but negative correlation was observed in late stages(CV–adult). Our results indicated that C. hyperboreus can benefit from primary production increase through accelerated development in the first growth season and the productive CS-slope area is a potential source for slope-basin replenishment.展开更多
The forecast of growing air transport in the upcoming decades faces the challenge of an increasing environmental impact.Aviation industry is working on promising technologies to mitigate this environmental impact.Ligh...The forecast of growing air transport in the upcoming decades faces the challenge of an increasing environmental impact.Aviation industry is working on promising technologies to mitigate this environmental impact.Lightweight design is a strong lever to lower the fuel consumption and,consequently,with it the emissions of aviation.High performance composites are a key technology to help achieve these aims thanks to their favourable combination of mechanical properties and low weight in primary structures.However,mainly synthetic materials such as petrol based carbon fibres and epoxy resins are used nowadays to produce composite in aviation.Renewable materials like bio-based fibres and resin systems offer potential environmental advantages.However,they have not found their way into aviation,yet.The reasons are reduced mechanical properties and,especially for the use of natural fibres,their flammability.Improvements of these shortcomings are under investigation.Therefore the application of bio-based and recycled materials in certain areas of the aircraft could be possible in the future.Good examples for applications are furnishings and secondary structures.The motivation for this paper is to give an overview of potential environmental properties by using such eco-materials in aviation.Life cycle assessment(LCA) is a tool to calculate environmental impacts during all life stages of a product.The main focus is laid on the bio-fibres flax and ramie,recycled carbon fibres and bio-based thermoset resin systems.Furthermore an overview of environmental aspects of existing composite materials used in aviation is given.Generally,a lack of LCA results for the substitution of synthetic materials by bio-based/recycled composite materials in aviation applications has been identified.Therefore,available information from other transport areas,such as automotive,has been summarized.More detailed LCA data for eco-composite materials and technologies to improve their properties is important to understand potential environmental effects in aviation.展开更多
This paper is concerned with so-called index d generalized cyclotomic mappings of a finite field F_(q), which are functions F_(q)→F_(q) that agree with a suitable monomial function x↦axr on each coset of the index d ...This paper is concerned with so-called index d generalized cyclotomic mappings of a finite field F_(q), which are functions F_(q)→F_(q) that agree with a suitable monomial function x↦axr on each coset of the index d subgroup of F_(q)^(*). We discuss two important rewriting procedures in the context of generalized cyclotomic mappings and present applications thereof that concern index d generalized cyclotomic permutations of F_(q) and pertain to cycle structures, the classification of (q−1)-cycles and involutions, as well as inversion.展开更多
基金Supported by the Special Funds for Major State Basic Research Project of China(No.2009CB220104)the Science and Technology Bureau of Shenyang, China(Nos.108149-2-00, 1091242-6-00)
文摘1 Introduction Low-dimensional nanostructures, such as nanorods, nanowires, and nanotubes, have received much attention for their superior optical, electrical, catalytic and magnetic properties. Owing to their low dimensionality and quantum continement effect, low-dimensional nanoscale materials can be exploited as fundamental building blocks for nanoscience and nanodevices^[1-3]. In recent years, efforts have been devoted to develop new approaches to synthesize one-dimensional(lD) nanostructrued vanadium oxides or vanadates materials, such as V205, NaV2Os, and CuV206, which have been widely investigated in catalytic or electrochemical fields due to their outstanding structural flexibility^[4-6].
基金provided by Technical Education Quality Improvement Programme-Ⅱ(TEQIP-Ⅱ)at MNNIT Allahabad
文摘In the present study, bond-coats for thermal barrier coatings were deposited via air plasma spraying(APS) techniques onto Inconel 800 and Hastelloy C-276 alloy substrates. Scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), and atomic force microscopy(AFM) were used to investigate the phases and microstructure of the as-sprayed, APS-deposited Co Ni Cr Al Y bond-coatings. The aim of this work was to study the suitability of the bond-coat materials for high temperature applications. Confirmation of nanoscale grains of the γ/γ′-phase was obtained by TEM, high-resolution TEM, and AFM. We concluded that these changes result from the plastic deformation of the bond-coat during the deposition, resulting in Co Ni Cr Al Y bond-coatings with excellent thermal cyclic resistance suitable for use in high-temperature applications. Cyclic oxidative stability was observed to also depend on the underlying metallic alloy substrate.
基金The National Natural Science Foundation of China under contract No.40406002the Public Science and Technology Research Funds Projects of Ocean under contract No.201105022
文摘Shelf-basin advection is essential to subsistence of the Arctic copepod Calanus hyperboreus population in high basin area. Its abundance, population structure and body size in pelagic layer were investigated with samples collected over a large range in the western Arctic Ocean during summer 2003, to evaluate the geographical variation in recruitment pattern. Calanus hyperboreus was absent from the shallow areas of the Chukchi Sea and most abundant in the slope area between the Chukchi Sea and Chukchi Abyssal Plain(CS-slope). Total abundance varied between 1 110.0 and 5 815.0 ind./m^2 in the CS-slope area and ranged from 40.0 to 950.0 ind./m^2 in the other areas. Early stages(CI–IV) dominated in the CS-slope area, whereas CV and adult females were frequently recorded only in deep basin areas. Geographical difference of prosome length was most evident in CIII,with average ranging from 2.48 to 2.61 mm at the CS-slope stations and 2.16–2.37 mm at the others. Abundance of early developmental stages(CI–CIV) correlated positively with Chl a concentration, but negative correlation was observed in late stages(CV–adult). Our results indicated that C. hyperboreus can benefit from primary production increase through accelerated development in the first growth season and the productive CS-slope area is a potential source for slope-basin replenishment.
基金supported by the European Union's Horizon 2020 research and innovation programme(Grant No.690638)the Ministry for Industry and Information of the People's Republic of China(Grant No.[2016]92)
文摘The forecast of growing air transport in the upcoming decades faces the challenge of an increasing environmental impact.Aviation industry is working on promising technologies to mitigate this environmental impact.Lightweight design is a strong lever to lower the fuel consumption and,consequently,with it the emissions of aviation.High performance composites are a key technology to help achieve these aims thanks to their favourable combination of mechanical properties and low weight in primary structures.However,mainly synthetic materials such as petrol based carbon fibres and epoxy resins are used nowadays to produce composite in aviation.Renewable materials like bio-based fibres and resin systems offer potential environmental advantages.However,they have not found their way into aviation,yet.The reasons are reduced mechanical properties and,especially for the use of natural fibres,their flammability.Improvements of these shortcomings are under investigation.Therefore the application of bio-based and recycled materials in certain areas of the aircraft could be possible in the future.Good examples for applications are furnishings and secondary structures.The motivation for this paper is to give an overview of potential environmental properties by using such eco-materials in aviation.Life cycle assessment(LCA) is a tool to calculate environmental impacts during all life stages of a product.The main focus is laid on the bio-fibres flax and ramie,recycled carbon fibres and bio-based thermoset resin systems.Furthermore an overview of environmental aspects of existing composite materials used in aviation is given.Generally,a lack of LCA results for the substitution of synthetic materials by bio-based/recycled composite materials in aviation applications has been identified.Therefore,available information from other transport areas,such as automotive,has been summarized.More detailed LCA data for eco-composite materials and technologies to improve their properties is important to understand potential environmental effects in aviation.
文摘This paper is concerned with so-called index d generalized cyclotomic mappings of a finite field F_(q), which are functions F_(q)→F_(q) that agree with a suitable monomial function x↦axr on each coset of the index d subgroup of F_(q)^(*). We discuss two important rewriting procedures in the context of generalized cyclotomic mappings and present applications thereof that concern index d generalized cyclotomic permutations of F_(q) and pertain to cycle structures, the classification of (q−1)-cycles and involutions, as well as inversion.