Compact x-ray microtomography system for element mapping and absorption imaging

We have designed and built a compact x-ray microtomography system to perform element mapping and absorption imaging by exploiting scanning fluorescence tomography and full-field transmission microtomography, respectively. It is based on a low power microfocus tube and is potentially appropriate for x-ray diagnostics in space. Full-field transmission tomography yields the three-dimensional inner structure of an object. Fluorescence microtomography provides the element distribution on a virtual section through the sample. Both techniques can be combined for appropriate samples. Microradiography as well as fluorescence mapping are also possible. For fluorescence microtomography a small and intensive microbeam is required. It is generated using a polycapillary optic. Operating the microfocus tube with a molybdenum target at 12 W, a microbeam with a full width at half maximum lateral extension of 16 microm and a flux of about 10(8) photonss is generated. As an example of application, this beam is used to determine the element distribution inside dried plant samples. For full-field scanning tomography, the x-ray optic is removed and the sample is imaged in magnifying projection onto a two-dimensional position sensitive detector. Depending on the sample size, a spatial resolution down to about 10 microm is possible in this mode. The method is demonstrated by three-dimensional imaging of a rat humerus.     

The relevance of global energy governance for Arab countries: The case of Morocco

Global climate and energy governance have led to the creation of a wide range of international and regional institutions, initiatives and financial mechanisms dedicated to fostering renewable energies. Furthermore, a low-carbon economy has evolved in recent years. The objective of this paper is to assess the potential benefits and merits of these institutions, initiatives and mechanisms from the perspective of the Middle East and North Africa (MENA) region. The central questions are if and how these organizations, initiatives and finance mechanisms could support a country from MENA in its efforts to implement large-scale capacities for renewable energy production. For this purpose, Morocco was chosen as a case study. The findings in this paper indicate that the existing institutions and financial mechanisms do not sum up to a coordinated governance approach, although the main needs of a country or region appear to be addressed. The existing institutions and financial mechanisms vary significantly in their ability to support countries, especially those taking the lead in renewable energy implementation.     

Ein Verfahren zur Bestimmung der Kohlenstoffketten-Verteilung in Gemischen oxäthylierter aliphatischer Amine

A Procedure for Determination of the Distribution of Carbon Chains in Mixtures of Alkoxylated Aliphatic Amines Technological properties of alkoxylated products depend on the total content of alkoxy groups, distribution of their homologues and on the nature of hydrophobic part of their molecules. A method was developed, which helps to ascertain as to which fatty amines or mixtures of fatty amines constitute the hydrophobic base of alkoxylated amines. In this test, N-alkyl morpholine in an amount which is equivalent to the basic amine is formed from alkoxylated fatty amine by digestion of the latter with 20% hydrochloric acid at 180°C in a sealed tube. Subsequently, the N-alkyl morpholine or the mixture of N-alkyl morpholines are separated as free bases according to the length of N-alkyl chain by gas chromatography. The method can be applied directly for saturated alkoxylated amines; the corresponding unsaturated compounds must, however, be hydrogenated prior to analysis.     

Trace-impurity detection by Rutherford backscattering and nuclear resonance reactions

The use of a multisegment annular Si detector together with a multiline electronic processing system has led to an improvement of the detection limit in Rutherford backscattering spectrometry by about two orders of magnitude as compared to the standard single-line arrangement. With regard to nuclear reaction analysis, using particle/γ-ray resonance processes, similar large enhancements have been realized by an effective background-suppression system eliminating environmental and cosmic radiation. The present state of both experimental facilities will be demonstrated and compared with other trace-element detection techniques.