A Three-Dimensional Two-Phase Model for Thermal Plasma Chemical Vapor Deposition with Liquid Feedstock Injection

In this paper, a comprehensive model for thermal plasma chemical vapor deposition (TPCVD) with liquid feedstock injection is documented. The gas flow is assumed to be steady, of a single temperature. Radiation and charged species contributions are excluded, but extensive homogeneous and heterogeneous chemistry is included. The liquid phase is traced by considering individual droplets. Discussion on the model's application to diamond production from acetone in a hydrogen–argon plasma is included. The major conclusions are: (1) Liquid injection possesses a capability to deliver the hydrocarbon precursor directly onto the deposition target. (2) For the case of complete evaporation of the droplet before reaching the substrate, the deposition rate is similar to that obtained with gaseous precursors. (3) The computational results compare well with experimental data. The modeling results can be used to optimize the injection parameters with regard to the deposition rate.     

Review: mass spectrometry of step-growth polymers

For at least two decades different mass spectrometric techniques have been applied for polymer analysis, including the qualitative determination of chemical compositions, end group identification, functionality type distribution and the determination of the cyclisation extend at each degree of polymerisation. Molecular weights exceeding 100 KDa are provable by MALDI-ToF mass spectrometry. Further, molecular weight distributions are determined by MADLI-ToF. However, there are some hints that, there is a discrimination against higher molecular weight species in samples with polydispersity of more than 1.2. Furthermore, pathways for dendritic and hyper-branched polymers, supramolecular polymers and nano condensates are analysed by help of mass spectrometry.     

Randregularität des\bar \partial -Problems für die Halbkugel in ℂn

Let f be a -closed (0, q+1)-form defined on the half ball B₊ in ⁿ, which is of class C^k on ¯B. We prove the existence with C^k-estimates of a solution u of the equation .

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Die Anregung zu dieser Arbeit verdanke ich auch Herrn Piotr Jakóbczak aus Krakau, der sich eine gewisse Zeit am Max-Planck-Institut für Mathematik in Bonn aufhielt. Während dieser Zeit untersuchten wir die C⁰-Abschätzungen für die Halbkugel in ⁿ     

Biosynthesis of isoprenoids. purification and properties of IspG protein from Escherichia coli

[Structure: see text]. The IspG protein is known to catalyze the transformation of 2-C-methyl-d-erythritol 2,4-cyclodiphosphate into 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate in the nonmevalonate pathway of isoprenoid biosynthesis. We have found that the apparent IspG activity in the cell extracts of recombinant Escherichia coli cells as observed by a radiochemical assay can be enhanced severalfold by coexpression of the isc operon which is involved in the assembly of iron-sulfur clusters. The recombinant protein was isolated by affinity chromatography under anaerobic conditions. With a mixture of flavodoxin, flavodoxin reductase, and NADPH as the reducing agent, stringent assay methods based on photometry or on 13C NMR detection of multiply 13C-labeled substrate/product ratios afforded catalytic activities greater than 60 nmol mg(-1) min(-1) for the protein "as isolated" (i.e., without reconstitution of any kind). Lower apparent activities were found using photoreduced deazaflavin as an artifactual electron donor, whereas dithionite was unable to serve as an artificial electron donor. The apparent Michaelis constant for 2-C-methyl-D-erythritol 2,4-cyclodiphosphate was 700 microM. The enzyme was inactivated by EDTA and could be reactivated by Mn2+. The pH optimum was at 9.0. The protein contained 2.4 iron ions and 4.4 sulfide ions per subunit. The replacement of any of the three conserved cysteine residues afforded mutant proteins which were devoid of catalytic activity and contained less than 6% of Fe2+ and less than 23% of S2- as compared to the wild-type protein. Sequence comparison indicates that putative IspG proteins of plants, the apicomplexan protozoan Plasmodium falciparum, and bacteria from the Bacteroidetes/Chlorobi group contain an insert of about 170-320 amino acid residues as compared with eubacterial enzymes.