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Träfflista för sökning "WFRF:(Hofmann S) srt2:(1996-1999)"

Sökning: WFRF:(Hofmann S) > (1996-1999)

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  • Dujon, B, et al. (författare)
  • The nucleotide sequence of Saccharomyces cerevisiae chromosome XV
  • 1997
  • Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 387:6632, s. 98-102
  • Tidskriftsartikel (refereegranskat)abstract
    • Chromosome XV was one of the last two chromosomes of Saccharomyces cerevisiae to be discovered(1). It is the third-largest yeast chromosome after chromosomes XII and IV, and is very similar in size to chromosome VII. It alone represents 9% of the yeast genome (8% if ribosomal DNA is included). When systematic sequencing of chromosome XV was started, 93 genes or markers were identified, and most of them were mapped(2). However, very little else was known about chromosome XV which, in contrast to shorter chromosomes, had not been the object of comprehensive genetic or molecular analysis. It was therefore decided to start sequencing chromosome XV only in the third phase of the European Yeast Genome Sequencing Programme, after experience was gained on chromosomes III, XI and II (refs 3-5). The sequence of chromosome XV has been determined from a set of partly overlapping cosmid clones derived from a unique yeast strain, and physically mapped at 3.3-kilobase resolution before sequencing. As well as numerous new open reading frames (ORFs) and genes encoding tRNA or small RNA molecules, the sequence of 1,091,283 base pairs confirms the high proportion of orphan genes and reveals a number of ancestral and successive duplications with other yeast chromosomes.
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  • Hofmann, H., et al. (författare)
  • Potential of nanosized ceramic powder for functional applications
  • 1997
  • Ingår i: Ceramic Engineering and Science Proceedings. ; , s. 687-694
  • Konferensbidrag (refereegranskat)abstract
    • Nanophase ceramic particles are building-blocks for the formation of nanostructured ceramics and are important in a composite for functional applications. Different synthesis methods for nanosized ceramics were developed. Depending on the method and chemical composition, powders which are agglomerates of nanosized primary particles exist. These primary particles show very small grain size distribution.
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  • Scholz, S. M., et al. (författare)
  • Mie scattering effects from monodispersed ZnS nanospheres
  • 1998
  • Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 83:12, s. 7860-7866
  • Tidskriftsartikel (refereegranskat)abstract
    • Transmission spectra of monodispersed particles exhibit pronounced resonance features from which particle properties can be deduced. ZnS powders were used as model materials since they can be synthesized by homogeneous precipitation with a narrow size distribution. The optical extinction spectra can be simulated using Mie scattering theory, and can be used as an in situ diagnostic tool for following the growth of particles during precipitation reactions. Using results of particle diameter measurements by other methods, information on the refractive index of the particles can be retrieved, indicating a highly porous internal structure of the spheres. Distinct features in the experimental and simulated spectra have been interpreted as to arise from circumference and diameter resonance effects in the particles. The simultaneous observation of these two effects allows one to estimate size and solid volume fraction from simple transmission spectra by application of an effective-medium model for the simulation parameters. The potential of application of Mie resonance effects for selective light screening or as pigments are discussed.
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8.
  • Scholz, S. M., et al. (författare)
  • Nanoporous Aggregates of ZnS Nanocrystallites
  • 1998
  • Ingår i: Applied organometallic chemistry. - : John Wiley & Sons. - 0268-2605 .- 1099-0739. ; 12:5, s. 327-335
  • Tidskriftsartikel (refereegranskat)abstract
    • During the synthesis of ZnS powders by wet chemical precipitation, the formation of nanoporous spheres is observed. The powders have been investigated using thermogravimetric analysis, X-ray diffraction and optical spectroscopies. Nanopore formation can be explained by several stages of growth. The formation of nanoparticles as primary particles is followed by their agglomeration forming secondary particles. These secondary particles are monodispersed spheres with a considerable porosity, because the agglomeration of the nanoparticles is unlikely to be volume-filling. The voids or nanopores formed by this agglomeration process in the secondary particles is estimated to comprise around 35% of the sphere volume. They are mainly filled with water and the residues of the chemical reagents. Water in the pores partially reacts with ZnS and forms hydrated sulphates. The chemical reagents used for the precipitation reactions are also found to be bound to the nanocrystallite's surfaces as ligands in some cases. Depending on the reaction conditions and reagents, the agglomeration of the nanoparticles can also be modified or hindered by the use of complexing agents acting as a sterically stabilizing surface layer on the nanocrystallites. The agglomeration of nanoparticles to larger units being a general phenomenon, this use of complexing agents to control pore formation and agglomerate size should be applicable to other nanocrystalline systems.
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  • Scholz, S. M., et al. (författare)
  • Raman spectroscopic study of silicon nanopowders
  • 1997
  • Ingår i: Journal of Materials Science & Technology. - : Chinese Society of Metals. - 1005-0302. ; 13:4, s. 327-332
  • Tidskriftsartikel (refereegranskat)abstract
    • Vibrational properties of silicon nanopowders are discussed with reference to Raman spectroscopic measurements. The powders were produced in a low pressure rf plasma from the cluster induced agglomeration of positive ions formed during the dissociation of silane. Influence of thermal treatment and the crystallization phenomena of the powder were studied. Raman spectroscopic measurements reveal size quantization effects for the particles as well as the existence of partially ordered regions in the apparently amorphous primary particles. The crystalline and amorphous volume fraction in the material were calculated from the relative spectral intensities. The results obtained in these experiments are consistent with the observations from recent high resolution transmission electron microscopy studies of these powders.
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