Filtern
Erscheinungsjahr
Dokumenttyp
Sprache
- Englisch (11) (entfernen)
Schlagworte
- 3D micro XRF (1)
- Abdominal appendages (1)
- Adult insects (1)
- Archaeometry (1)
- Bauplan (1)
- Blends (1)
- Building of the storage facility (1)
- CT (1)
- Cultural heritage (1)
- Flame retardance (1)
Organisationseinheit der BAM
Polycapillary halflenses are widely used to focus X-ray radiation onto a small spot. Additionally they can reduce the field of view of a semiconductor detector when placed in front of one. In 3D micro X-ray fluorescence spectroscopy (3D Micro-XRF) with synchrotron radiation, two polycapillary halflenses are used in a confocal geometry. Up until now, characterization measurements in the focal plane have only been performed in the case of the lens focusing parallel radiation. Assumptions have been made, that in the other case, when isotropic radiation from a spot source is transported to a detector, the acceptance distribution in the focal plane is also Gaussian. We performed measurements with an electron beam as well as a proton beam which confirm this assumption. In addition, a comparison between measurements in collecting and focusing mode show differences in spot size and transmission. These differences exemplify the fact that there is not one global spot size or transmission function of a polycapillary halflens. Illumination and divergence effects can alter both characteristic lens parameters.
Phase Behaviour of Copolymers Containing Cholesterol and 4,4' Methoxybiphenyl as Mesogenic Group
(1996)
Influence of Chirality on Phase Behaviour of Copolymers Containing Cholesterol as Mesogenic Group
(1996)
In this work, the applicability of a new 3D micro X-ray fluorescence (3D Micro-XRF) laboratory spectrometer for the investigation of historical glass objects is demonstrated. The non-destructiveness of the technique and the possibility to measure three-dimensionally resolved fluorescence renders this technique into a suitable tool for the analysis of cultural heritage objects. Although absorption and resolution effects complicate qualitative analysis of the data, layered structures can be distinguished from homogeneous samples without the need for full quantification. Different manufacturing techniques were studied in this work with the help of hand-made reference samples. With the gained knowledge it could be shown for the investigated historical glass object, that black enamel as a stained glass contour colour was used in a cold painting. The object was not fired after the application of the black enamel, but instead the adhesion of the paint was solely provided through organic binding agents and the backing with metal foils. Thus, for the manufacturing of the object, a mixture of cold painting technique with a stained glass color was used. Quantitative measurements with a 3D Micro-XRF setup at the Berlin synchrotron BESSY II confirm the assumptions drawn on the basis of the qualitative investigation with the 3D Micro-XRF spectrometer with X-ray tube excitation.
Flame retarded poly(butylene terephthalate) (PBT) is required for electronic applications and is mostly achieved by low molar mass additives so far. Three phosphorus-containing polyesters are suggested as halogen-free and polymeric flame retardants for PBT. Flame retardancy was achieved according to cone calorimeter experiments showing that the peak heat release rate and total heat evolved were reduced because of flame inhibition and condensed-phase activity. The presented polymers containing derivatives of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide form immiscible blend systems with PBT. Shear-rheology shows an increase in storage moduli at low frequencies. This is proposed as quantitative measure for the degree of phase interaction. The phase structure of the blends depends on the chemical structure of the phosphorus polyester and was quite different, depending also on the viscosity ratio between matrix and second phase. A lower viscosity ratio leads to two types of phases with spherical and additionally continuous droplets. Addition of the flame retardants showed no influence on the dielectric properties but on the mechanical behavior. The polymeric flame retardants significantly diminish the impact strength because of several reasons: (1) high brittleness of the phosphorus polyesters themselves, (2) thermodynamic immiscibility, and (3) weak phase adhesion. By adding a copolymer consisting of the two base polymers to the blend, an improvement of impact strength was obtained. The copolymer particularly acts as compatibilizer between the phases and therefore leads to a smaller phase size and to a stronger phase adhesion due to the formation of fibrils.
Despite their enormous diversity, the bauplan of adult winged insects (pterygotes) is remarkably conservative since the Lower Devonian: a five-segmented head, a three-segmented thorax with three pairs of walking legs and an eleven-segmented abdomen without any non-sexual appendages 1 and 2. The only known exceptions are the abdominal appendages of adult male sepsid flies on the fourth segment; however, these are also used as copulatory organs and are supposedly maintained through sexual selection [3]. Here, we report a rod-like paired appendage from the third and fourth abdominal segments in adults of the Southeast-Asian Hemiptera taxon Bennini (Figure 1A,B; Supplemental information). These are fully musculated, innervated, and movable and bear highly organized sensory and secretory units. The appendages, termed LASSO (lateral abdominal sensory and secretory organs), are consistent in topology and structure in all species studied and not sexually dimorphic. The existence of these non-sexual abdominal appendages reveals the potential of the 300 million year old conserved bauplan of insects.
This publication summarizes the work carried out during an IAEA coordinated research project (CRP) on safe and reliabe management of spent nuclear fuel. This work contributes to the overall goal of demonstrating the performance of spent nuclear fuel and related storage systems components over long durations, and facilitates the transfer of this knowledge to Member States. The technical areas addressed by the CRP participants were related to potential degradation mechanisms in metal casks and concrete overpacks, such as stress corrosion cracking; long term integrity and performance of the fuel cladding; thermo-mechanical behaviour of the metal seals; and long term gamma and neutron shielding capability. The participants also considered past and ongoing demonstration programmes. For each technical topic addressed the main conclusions have been drawn, including information on the development of specific monitoring and inspection techniques as well as future opportunities for closing relevant data gaps. A major achievement is also the establishment of a worldwide network of experts working on current research projects to demonstrate the long term performance of spent fuel in dry storage systems.