Browsing by Author "Li, Feng"

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Open Access
Investigation of urban sprawl on the basis of remote sensing data : a case study in Jiangning, Nanjing City, China
(2012) Li, Feng; Siedentop, Stefan (Prof. Dr.-Ing.)
The dissertation is continuing research on the project named "Sustainable Development by Integrated Land Use Planning (SILUP) ", which has been completed cooperatively by both Chinese and German research institutions, taking Jiangning District as a typical research area to recognize the spatial patterns, monitor dynamic change, measure distinct extents, analyze the driving forces and access impacts of urban sprawl based on the technology of Remote Sensing (RS), Geographic Information System (GIS) and so on. Over the past 30 years, urban development in China has been remarkable. Land development and consumption have been out of control and kept expanding massively, especially to marginal areas of some metropolises. The undesirable growth patterns in Chinese cities appear to threaten the goal of sustainable development and impose some costs socially, economically and environmentally on households, firms and governments. At present, the research on urban sprawl in China is still in a preliminary stage- the basic characteristics of urban sprawl are not explicitly defined and the understanding of its internal mechanisms has been maintained at the level of empirical theory. The dissertation deals with the existing literatures on the subject of urban sprawl, undertaking a thorough review in terms of similarities and differences, consensuses and disagreements among many researchers and publications by comparing definitions, indicators, causes and costs between the sprawl in Western countries and China. Looking at the example of the United States, urban sprawl occurred within a perfect market economic system. However, urban sprawl in many cities of China has emerged during a transition period of China's economy from a planned economic system to a market economic system. Is it appropriate to transfer the Western conceptualization of urban sprawl to China? To what extent can these results be applicable to China? Therefore, it is urgent necessary to find ways to research urban sprawl in Chinese cities. Key questions should be answered: What is the exact definition of urban sprawl? How do we express the basic characteristics of urban sprawl explicitly? What are the internal mechanisms of urban sprawl? What are the driving forces and impacts of sprawl? The objective of this dissertation is to structure a complete framework for areas in China which have similar development backgrounds as Jiangning, provide ideas of urban sprawl study in some developing countries which also have similar a development background with Jiangning and give references and ideas for comparative study on the problem of urban sprawl between areas in Western countries and China. This dissertation intends to provide some cautions to decision-makers which they can use to implement good planning for the future development of Jiangning.
Open Access
Synthesis of branched amino acids : isonorstatine, phenylisothreonine, lactacystin analogues, and amino polyols
(2007) Li, Feng; Jäger, Volker (Prof. Dr.)
The 1,2-aminoalcohol fragment is found in many natural products and drugs, for example as a central moiety of non-proteinogenic amino acids. It is also an integral part of doxorubicin and daunomycin, which have been used for the treatment of human malignancies. There is, therefore, a particular interest in the synthesis of branched amino hydroxy acids such as isonorstatine, phenylisothreonine, amino polyols and lactacystin derivatives. Norstatine is part of amastatin, an inhibitor of leucine amino-peptidase, and a fragment of a new human renin inhibitor, KRI-1230. Due to the importance of this kind of compounds, new routes have been explored to synthesize various branched amino acids, such as isonorstatine and its derivatives. The key step is a highly stereoselective addition of 1-butene-3-yl Grignard reagent to an L-threose-derived imine. Phenylisoserine constitutes the side-chain of taxol, a drug which has been approved for treatment of ovarian cancer by U.S. FDA. A novel methyl-branched analogue of phenylisoserine, the phenylisothreonine methyl ester 36, was obtained by addition of methylmagnesium bromide to a protected-L-threose derivative followed by addition of phenyl to the derived nitrone. Amino-hydroxymethyl-cyclopentane polyols of type are known to be potent inhibitors of hydrolytic enzymes (glycosidases). The derivative was obtained via intramolecular [3 + 2] cyclization of nitrone and olefin. Lactacystin, a microbial natural product, is an inhibitor of mammalian 20S proteasome which is a large and highly conserved multi-catalytic proteinase complex that constitutes the catalytic core of the 26S proteasome, present in all eukaryotic organisms. Analogues of lactacystin were synthesized starting from 3-(methoxymethoxy)-2-methylprop-1-ene.