Henning Osholm Sørensen

Determining grain resolved stresses in polycrystalline materials using three‐dimensional X‐ray diffraction

An algorithm is presented for characterization of the grain resolved (type II) stress states in a polycrystalline sample based on monochromatic X-ray diffraction data. The algorithm is a robust 12-parameter-per-grain fit of the centre-of-mass grain positions, orientations and stress tensors including error estimation and outlier rejection. The algorithm is validated by simulations and by two experiments on interstitial free steel. In the first experiment, using only a far-field detector and a rotation range of 2 × 110°, 96 grains in one layer were monitored during elastic loading and unloading. Very consistent results were obtained, with mean resolutions for each grain of approximately 10 µm in position, 0.05° in orientation, and 8, 20 and 13 × 10−5 in the axial, normal and shear components of the strain, respectively. The corresponding mean deviations in stress are 30, 50 and 15 MPa in the axial, normal and shear components, respectively, though some grains may have larger errors. In the second experiment, where a near-field detector was added, ∼2000 grains were characterized with a positional accuracy of 3 µm.

The Ilímaussaq intrusion—progressive crystallization and formation of layering in an agpaitic magma

Summary Agpaitic rocks form the major part of the Ilímaussaq intrusion in S Greenland. The agpaitic magma developed as the narrow top zone in a large stratified basalt-syenite magma chamber at depth. The extreme composition of the agpaitic magma is related to an unusually high crustal position of the cupola. After emplacement, the agpaitic magma developed in an essentially closed system. The magma chamber was shallow and the volatile-rich alkaline magma was light and fluid. Heat loss was mainly through the roof, and the earliest agpaitic rocks crystallized successively downwards from the roof. The magma was probably well mixed in the early stage, but there is evidence for accumulation of residual components in a layer below the roof. This accumulation of low-melting components eventually suppressed the downwards crystallization of the roof rocks. The exposed floor rocks, kakortokites and lujavrites, are younger than the roof rocks, and at this stage the magma had probably developed repeated layering. The layering in the kakortokites, with density-graded units 7 m thick repeated continuously over the whole exposed floor, can be simply explained if they formed from a layered magma by successive upwards crystallization of individual layers. The magma at this stage was nearly volatile saturated, and each layer crystallized in response to the upward loss of a certain amount of volatiles. The lujavrites conformably overlie the kakortokites and formed after a roof collapse which caused the rate of heat loss from the remaining magma to increase. The upward crystallization became faster than the upward transport of residual components, and the successive lujavrites contain more and more of these components which finally gave rise to potentially economic concentrations of U, Be and other rare elements. Finally, a hydrothermal phase was lost from the system.

X-ray microscopy in four dimensions

Three-dimensional X-ray diffraction (3DXRD) microscopy offers the possibility of time-resolved mapping of structures down to the micrometer scale 1 , 2 , 3 , 4 , 5 , 6 , i.e. four-dimensional studies. In this review, the principles of the 3DXRD microscope are described and various examples of its applications are presented.

Hydrocarbon gases and bituminous substances in rocks from the Ilímaussaq alkaline intrusion, South Greenland: (Contribution to the Mineralogy of Ilímaussaq No. 18)

Samples of poikilitic sodalite syenite (naujaite), sodalite foyaite and augite syenite from the Ilimaussaq alkaline intrusion in South Greenland contain hydrocarbons in vacuoles in the minerals and in intergranular micro-pores. Samples of lujavrite and gabbro have very low gas contents. Methane is the predominant hydrocarbon; the contents of CO2 and CO are insignificant. The carbon of the hydrocarbon gases of naujaite is enriched in C13. The rocks contain disseminated bituminous substances composed mainly of oil, alcohol-benzol resins and asphaltenes. The hydrocarbon gases and the bituminous substances are thought to be inorganic origin. The methods of examination are described.

Assessment of the Nasopharyngeal Airway: A Rhinomanometric and Radiographic Study in Children with Adenoids

An assessment of the nasopharyngeal airway in 24 children referred to hospital for adenoidectomy was based on symptoms, radiography and rhinomanometry. The only symptom that was significantly correlated to a small size of the nasopharyngeal airway was Snoring. By radiography, measurement of the airway as well as of the depth of soft tissue of the posterior wall was found well correlated to nasal respiratory resistance which was measured by a new technique. By this, rhinomanometry could be performed in all children down to the age of 5 years. Both radiography and rhinomanometry give valuable parameters for the indication of adenoidectomy.

Clinical Application of Continuous Threshold Recording

Continuous threshold for a pure tone (2000 cps) was recorded in 93 normal individuals and in 355 patients with impaired hearing. In normal individuals, no threshold rise above 10 db was recorded. In pure conductive deafness the threshold also remained constant. Among patients with otosclerosis a few showed more pronounced tone decay; in the majority the threshold was constant. About half of the patients with cochlear deafness showed no tone decay; in the other half a moderate tone decay was observed. In retrococh-lear deafness, pronounced tone decay was recorded in 85 %. Twelve patients with tumour of the cerebello-pontine angle all showed pronounced tone decay. Pronounced tone decay is considered to be indicative of functional impairment, not only of the acoustic nerve, but also of the central auditory pathways. As the test is simple to perform, it is of value in the topical diagnosis.

Auditory Adaptation in Nerve Action Potentials Recorded from the Cochlea in Guinea Pigs

Urethane-anaesthetised guinea pigs were exposed to noise and pure-tone stimulation of low intensity (35-80 db). The effect of the exposure was measured on neural click responses recorded with gross electrodes from the basal turn of the cochlea. A depression of the neural activity, evidenced by a reduction of the amplitude of the click response, was demonstrated when the clicks were masked by white noise of moderate intensity. The poststimulatory effect was recorded after exposure to white noise or pure tones of varying frequencies. The recovery time was measured. The recovery time for the second of a pair of clicks was also recorded. A depression could not be provoked by stimulation of the contralateral ear, for which reason central inhibition could be excluded. The phenomenon is assumed to be the electrophysiological equivalent to auditory adaptation.

FabIO: easy access to two-dimensional X-ray detector images in Python

FabIO is a Python module written for easy and transparent reading of raw two-dimensional data from various X-ray detectors. The module provides a function for reading any image and returning a fabioimage object which contains both metadata (header information) and the raw data. All fabioimage objects offer additional methods to extract information about the image and to open other detector images from the same data series.

Tracheopathia Osteoplastica and Ozaena

A case of tracheopathia osteoplastica with concurrent ozaena is reported. The histological changes in the two affections are very much alike. The relationship, if any, between the two affections is discussed. The cause of tracheopathia osteoplastica is unknown, and no specific therapy is available. It may be supposed that, owing to the increasing use of bronchoscopy, the disease, which is often without symptoms, will be diagnosed more frequently during life in future.

Simultaneous variation of multipole parameters and Gram-Charlier coefficients in a charge-density study of tetrafluoroterephthalonitrile based on X-ray and neutron data.

Difficulties encountered in modelling the scattering of fluorine in organic compounds have been investigated through refinements of accurate X-ray and neutron diffraction data measured on tetrafluoroterephthalonitrile, TFT, at 122.4 K. Multipole refinements led to a highly contracted octopole on fluorine. The subsequent analysis revealed that fluorine does not possess a valence octopole but exhibits anharmonic thermal motion that can be modelled by the octopole multipole parameters. The scattering contribution from the octopole shows the same cubic dependence in the scattering vector as the Gram-Charlier expansion of the nuclear displacements to third order. The analysis also showed that refinement of third-order Gram-Charlier coefficients on fluorine requires data to at least 0.93 A(-1) resolution in sinthetas/lambda. The X-ray data extending to 1.27 A(-1) were of sufficient resolution to include third-order Gram-Charlier coefficients for N, F and the cyano C atoms in the refinement, whereas the neutron data only enabled refinement of the third-order Gram-Charlier coefficients for nitrogen. The refinements of the neutron and X-ray diffraction data yielded identical atomic displacement parameters for all the atoms. Though inclusion of anharmonic motion for N and F atoms provides the best model, it does not affect the crystal electron density, and all intramolecular bond critical points have identical features. Application of the anharmonic model, however, leads to small differences in the intermolecular interactions, which is illustrated by the electrostatic potential adjacent to the N atom. The characteristics of the C-F bond were elucidated by the topological analysis of the crystal electron density, which also supported the proposed quinonoid structure of the benzene ring.