Separation of enzymes from Candida boidinii crude extract by continuous flow zone electrophoresis.

Separation of the enzymes formate dehydrogenase, formaldehyde dehydrogenase and methanol oxidase from Candida boidinii crude extract has been explored using continuous flow zone electrophoresis in the VaP-22 and the scaled-up VaP-220 electrophoresis apparatus. Yields up to 95% and purification factors between 3 and 7 were obtained, together with separation of cell debris from the enzymes. Multiple injections of sample were used to obtain a protein throughput of 46.2 mg/h in the VaP-22. A tenfold higher throughput was achieved using the VaP-220. Correlation of the electrophoretic mobility in continuous flow zone electrophoresis with the elution behavior in ion-exchange chromatography confirmed the primary role of net surface charge in the separation of biological molecules. Proteins and enzymes with differences greater than 0.05 M elution molarities in ion-exchange chromatography can be separated. This corresponds to a preparative scale (mg/h or g/h) separation of proteins and enzymes whose difference in apparent electrophoretic mobility is greater than 0.70 x 10(-5) cm2/(V.s).     

1,2-Dialkoxyacenaphthylenes and 2,3,11,12-bis-(1,2-acenaphtho)-[18]crown-6

A general synthesis of 1,2-dialkoxyacenaphthylenes by dehydrogenation of the corresponding acenaphthene derivatives with high potential quinones is described. The new crown ether, 2,3,11,12-bis(1,2-acenaphtho)-[18]crown-6, 1, is obtained by this route. The surprisingly poor complexing ability of 1 is ascribed to electronic and geometrical effects of the acenaphthylene rings as shown by spectroscopic and voltammetric data and the crystal structure of the free ligand 1.     

An integral representation for decomposable measures of measurable functions

Summary We start with a measurem on a measurable space (,A), decomposable with respect to an Archimedeant-conorm on a real interval [0,M], which generalizes an additive measure. Using the integral introduced by the second author, a Radon-Nikodym type theorem, needed in what follows, is given.The integral naturally leads to a -decomposable measurem on the space of all measurable functions from to [0, 1]. The main result of the present paper is the converse of this, namely that, under natural conditions, any -decomposable measurem on can be represented as an integral of a certain Markov-kernelK. We extend this representation to measures on which have values in a set of distribution functions.These results generalize the work done by the first author in the case of additive measures.     

CEMS and DCEMS investigations of Al-implanted iron

-Fe surfaces were implanted with a nominal dose of 5×10¹⁷ Al ions/cm² at 50 keV and a current density of about 3.7 A/cm². Samples of different shapes and thicknesses have been used in order to test the influence of heat flow from specimen to target holder during implantation. Integral and energy differential (depth-selective)⁵⁷Fe conversion electron Mössbauer spectroscopy (CEMS and DCEMS) were employed. The spectra indicated a magnetic phase characterised by a broad hyperfine field distributionP(B _hf), a non-magnetic phase, and -Fe. The relative intensity of the non-magnetic phase was enhanced if the thermal contact during implantation became worse. An energy dependence of DCEM spectra in the L-electron range was observed. Model calculations using L-electron weight functions and experimental concentration profiles obtained by secondary neutral mass spectroscopy (SNMS) yielded fair agreement between calculated and experimental phase signals. The results demonstrate that the non-magnetic Fe-Al alloy phase with high Al concentration is located closer to the surface than the magnetic alloy phase, which extends to much larger depth than expected.     

Bone-ablation mechanism using CO2 lasers of different pulse duration and wavelength

Bone ablation using different pulse parameters and four emission lines of 9.3, 9.6, 10.3, and 10.6 m of the CO₂ laser exhibits effects which are caused by the thermal properties and the absorption spectrum of bone material. The ablation mechanism was investigated with light- and electron-microscopy at short laser-pulse durations of 0.9 and 1.8 s and a long pulse of 250 s. It is shown that different processes are responsible for the ablation mechanism either using the short or the long pulse durations. In the case of short pulse durations it is shown that, although the mineral components are the main absorber for CO₂ radiation, water is the driving force for the ablation process. The destruction of material is based on explosive evaporation of water with an ablation energy of 1.3 kJ/cm³. Histological examination revealed a minimal zone of 10–15 m of thermally altered material at the bottom of the laser drilled hole. Within the investigated spectral range we found that the ablation threshold at 9.3 and 9.6 m is lower than at 10.3 and 10.6 m. In comparison the ablation with a long pulse duration is determined by two processes. On the one side, the heat lost by heat conduction leads to carbonization of a surface layer, and the absorption of the CO₂ radiation in this carbonized layer is the driving force of the ablation process. On the other side, it is shown that up to 60% of the pulse energy is absorbed in the ablation plume. Therefore, a long pulse duration results in an eight-times higher specific ablation energy of 10 kJ/cm³.