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[en] This volume contains 97 contributions presented at he 2nd international conference on high nitrogen steel (HNS-90) in Aachen on October 10-12, 1990. The contributions dealt with the following topics: 1. Fundaments, 2. Properties, 3. Technology and 4. Applications. (MM)
[en] In the steel making process, it's hard to control the amount and the distribution of nitrogen. Also nitrogen makes spots in the PTA analysis. So it's very important to evaluate the effect of nitrogen on the PTA for the analysis of boron distribution. The objects of this report are like these. - Evaluation of nitrogen effect for analysis of boron distribution by PTA - Evaluation of nitrogen distribution of the boron-free steel by PTA
[en] A large increase of grasses Calamagrostis epigejos, Bromus inermis and Brachypodium pinnatum has often been observed in many regions enriched by higher nitrogen (N) wet deposition inputs. Competitive relationships between these grasses under enhanced N loads have not yet been studied. Therefore an outdoor experiment was established which involved monocultures of Calamagrostis, Bromus and Brachypodium and their 1:1 mixtures in containers under two N treatments, i.e., unfertilized and fertilized (+50 kg N ha−1). In monocultures, the total aboveground biomass of Calamagrostis, Bromus and Brachypodium were 1.1, 3.6 and 2.5 times higher respectively due to enhanced N fertilization. Relative crowding and aggressivity coefficients indicate that Calamagrostis and Bromus dominate when mixed with Brachypodium at both levels of N availability. When mixed with Bromus, Calamagrostis is the poorer competitor at lower N loads, however, it can be dominating in N fertilized treatments. - Highlights: ► A large increase of tall grasses has often been observed in many ecosystems. ► Data on competitive relationships between grasses were investigated. ► Competition indices indicate that Calamagrostis and Bromus dominate in mixtures with Brachypodium. ► Calamagrostis is a better competitor when mixed with Bromus but only at higher N loads. ► N deposition may play a critical role in the expansion and persistence of grasses in the landscape. - Competition abilities of Calamagrostis and Bromus were greater than Brachypodium and the competitive superiority of Calamagrostis to Bromus was in N rich substrate.
[en] Analysis of existing technologies of high-nitrogen steel production shows that rational nitrogen content in mass production corresponds to moderate high values. Such steels can be smelted under normal or slightly elevated pressure in steelmaking units, using processes of mass- and special metallurgy. High-nitrogen steels with ''overequilibrium'' nitrogen content are promising, but technology and equipment for production of them are complicated, and production of such steels is therefore limited. (orig.)
[en] The discovery of carbon nanotubes in 1991 opened up a challenging new area of research, because they are expected to be ideal building blocks for nanoscale applications due to their extraordinary mechanical and electronic properties. Various production methods have been developed, however precise control of nanotube morphology (e.g. length, diameter) has yet to be realised, a fact which has delayed industrial exploitation. Thus a comprehensive understanding of nanotube growth is essential, and this thesis is concerned with this important problem, i.e. the controlled production of novel carbon nanomaterials. Chapter 1 surveys production methods for fullerenes, carbon nanotubes and other carbon-based materials, such as fibres, particles etc. The sophisticated tools required for this work, e.g. high resolution transmission electron microscopy (HRTEM), high resolution electron energy loss spectroscopy (HREELS), etc. are reviewed in Chapter 2. Chapter 3 describes a novel approach to carbon nanotubes, using laser etching techniques, which generates aligned tubes of uniform diameter and length. The mode of catalyst preparation, as well as the nature of the precursor, play crucial roles in this process. The preparation of modified carbon nanotubes by the pyrolysis of metallocene, e.g. ferrocene in conjunction with various hydrocarbons, is discussed in Chapter 4. Superconducting interference device measurements (SQUID) show that Fe-filled carbon nanotubes exhibit enhanced coercivities in the 430-1070 Oe range, i.e. greater than those reported for Ni and Co nanowires. Carbon nanotubes can be also modified by replacing atoms of the carbon network with nitrogen, boron or both. The creation of large arrays of nitrogen-doped carbon nanotubes, for example CNx nanofibres, as well as the formation of BxCyNz onions is described in Chapter 5. Electron irradiation of these onions generates pure carbon onions. Finally (Chapter 6), the catalytic behaviour of metal particles in different systems is studied in order to determine the relationship between metal particle and tube morphology. (author)