The effects of surface oxidation on luminescence of nano diamonds

In this work we quantify and characterise the effects of air-oxidation on nitrogen-vacancy defect luminescence in both high-temperature-high-pressure and detonation synthesized nanodiamonds using Raman and luminescence spectroscopies. We find that oxidation treatments result in an increased nitrogen-vacancy centre excited state lifetime from 13 ns to 25 ns and in 5-nm diamonds the intensity of this luminescence increases by at least 5-fold. At the same time, in 5-nm diamonds, short lived surface-defect related luminescence is reduced by 10-fold. Furthermore we find that air oxidation reduces the sp² and disordered carbon fraction of nanodiamonds by up to 5-fold in 5-nm nanodiamonds. Based on these results, the authors suggest that the disordered-carbon and graphite shell of 5-nm nanodiamonds quenches nitrogen-vacancy luminescence, and that this quenching can be partially reduced by surface oxidation. These findings provide useful insights into the role of the graphite and disordered carbon shell in quenching luminescence, and have implications for the applicability of 5-nm nanodiamonds to bio- and quantum physics applications.     

Mixed effect modeling of sumatriptan pharmacokinetics during drug development. I: Interspecies allometric scaling

A sample of 22 subjects was studied from a population of adults who had suffered from bacterial meningitis in childhood. Audiovestibular, oculomotor and neuropsychological investigations were performed and quality of life was assessed. An age-matched control group of 20 subjects was recruited. In the meningitis group, nine subjects had abnormal pure tone audiograms. One was previously undiagnosed and a progression was found in four. There was an overrepresentation of subclinical vestibular pathology (6 out of 9 (67%)) in this group. Audiovestibular test results showed a peripheral pattern and oculomotor tests were normal. The quality of life scores of those with hearing loss were significantly higher than those in the control group. Neuropsychological tests of brain dysfunction were abnormal in six out of 22 (27%) who had recovered from meningitis. The prevalence of such dysfunctions was not related to audiovestibular disorder. The quality of life scores of those with brain dysfunctions were similar to those of the control group. The findings of reduced auditory memory and tone level perception in four out of 22 (18%), suggest that lesions of central auditory pathways may follow from bacterial meningitis. The results support the idea that inner ear damage is the major cause of hearing loss after bacterial meningitis. Despite the absence of brainstem involvement, central nervous system lesions with disturbed auditory processing and language functions can be of significance. The high frequency of discrete brain dysfunctions indicate that a thorough neuropsychological investigation is required after bacterial meningitis.     

Recommendations for standardized radiologic follow-up of thrust plate endoprosthesis

The thrust-plate endoprosthesis (TPE) is a cementless, total endoprosthetic replacement of the coxal femur with metaphysical anchorage. A combination of the TPE with an endoprosthetic cup component, which is also cementless, is recommended based on the concept of the TPE. The TPE requires a special radiological technique. In radiological follow-up examinations, the positioning area of the TPE, particularly on the resected femoral neck, is especially important. A gap-free, level positioning of the implant on the resected and flat-ground femoral neck is ideal. In order to be able to exactly judge the positioning area, the bony area and the TPE that lies on it should have no overlap in the anterio-posterior optical path of the X-ray and must be hit exactly orthogonally by the central X-ray beam. As radiological examinations of human femoral preparations show, this succeeds best with an inner rotation positioning of the femur from 10 to 20 degrees. According to our experience, especially in freshly operated patients, the positioning of the legs with the femur in a slightly abducted position (about 10-20 degrees) is better tolerated. Only when the positioning of the TPE cannot be exactly judged with the above-mentioned examination method should the examiner use an X-ray image intensifier. Experience has shown that this is only necessary in exceptional cases. In the present examination, the special problems of radiological examination of the TPE are discussed. Recommendations for standardized radiological examinations, as well as findings following TPE implantation, are given.     

Ermittlung mechanischer Kenndaten von Kohlenstoffaserverstärktem Kohlenstoff (CFC) mit dem Biege- und Zugversuch

Research on Mechanical Data of Carbon Reinforced Carbon (CC) in Bending and Tensile Mode CC is a ultra high temperature material used until 2200°C in inert atmospheres. The testing geometries of reinforced carbon (CC) are not standardized in West Germany today. Therefore the SIGRI GmbH has defined material specific geoand tensile mode. It is shown, that the tensile strength has a higher level than the bending strength when the laminate orientation is (0/90°). When the laminate has a (0/± 45/90°)-orientation, the relation is inverted. If the laminate orientation is known, the fracture mode can be predicted.     

Optimisation of monolithic lining concepts of channel induction furnace

Abstract

For the possible energy savings and extension of the volume capacity, the monolithic lining of a channel induction furnace was optimised in the following manner. Orthogonal array method is utilised to systematically design the lining concepts, and the finite element simulations including the temperature dependent properties of monoliths are carried out to determine the temperatures and stresses during the preheating and holding. In terms of the main effect analysis materials for the monolithic lining are recommended. Moreover, a thickness–thickness–temperature isothermal map is provided to show the acceptable thickness range of working and insulating linings. Nevertheless, for the final decision the deliberate consideration for the cost effectiveness of a certain lining concept is also necessary.     

Direct numerical simulation of laminar flame–wall interaction for a novel H2-selective membrane/injector configuration

Direct numerical simulations are performed to investigate the transient processes of laminar flame–wall interaction and quenching near a porous, permeable wall and compared against a reference case of a non-porous impermeable wall. A boundary condition formulation that models species (hydrogen in this case) transport through a permeable wall, driven by the fuel species partial pressure difference between the feed and the permeate side of a selective membrane, has been implemented in a high-order finite difference direct numerical simulation code for reactive flows (S3D) by Chen et al. (2009) [1]. The present results are obtained for lean, stoichiometric and rich initial mixture conditions on the permeate side of the permeable wall and indicate that the characteristic parameters of the flame–wall interaction (wall heat flux, quenching distance) are affected to a large extent by the presence of the membrane hydrogen flux. Concurrently, the hydrogen flux through the membrane is also strongly affected by the presence of the flame during the transient flame–wall interaction process, finally resulting in a strong feedback mechanism between the membrane hydrogen flux and the flame that greatly increases boundary layer flashback speeds at fuel lean conditions.