Novel clearance of muscle proteins by muscle cells

Blood levels of cardiac troponins (cTn) and myoglobin are analysed when myocardial infarction (MI) is suspected. Here we describe a novel clearance mechanism for muscle proteins by muscle cells. The complete plasma clearance profile of cTn and myoglobin was followed in rats after intravenous or intermuscular injections and analysed by PET and fluorescence microscopy of muscle biopsies and muscle cells. Compared with intravenous injections, only 5 % of cTnT, 0.6 % of cTnI and 8 % of myoglobin were recovered in the circulation following intramuscular injection. In contrast, 47 % of the renal filtration marker FITC-sinistrin and 81 % of cTn fragments from MI-patients were recovered after intramuscular injection. In addition, PET and biopsy analysis revealed that cTn was taken up by the quadriceps muscle and both cTn and myoglobin were endocytosed by cultured muscle cells. This local clearance mechanism could possibly be the dominant clearance mechanism for cTn, myoglobin and other muscle damage biomarkers released by muscle cells

Resonant Auger spectroscopy at the L2,3 shake-up thresholds as a probe of electron correlation effects in nickel

The excitation energy dependence of the three-hole satellites in the L3-M4,5M4,5 and L2-M4,5M4,5 Auger spectra of nickel metal has been measured using synchrotron radiation. The satellite behavior in the non-radiative emission spectra at the L3 and L2 thresholds is compared and the influence of the Coster-Kronig channel explored. The three-hole satellite intensity at the L3 Auger emission line reveals a peak structure at 5 eV above the L3 threshold attributed to resonant processes at the 2p53d9 shake-up threshold. This is discussed in connection with the 6-eV feature in the x-ray absorption spectrum.Comment: 8 pages, 4 figures; http://prb.aps.org/abstract/PRB/v58/i7/p3677_

On the interpretation of spin-polarized electron energy loss spectra

We study the origin of the structure in the spin-polarized electron energy loss spectroscopy (SPEELS) spectra of ferromagnetic crystals. Our study is based on a 3d tight-binding Fe model, with constant onsite Coulomb repulsion U between electrons of opposite spin. We find it is not the total density of Stoner states as a function of energy loss which determines the response of the system in the Stoner region, as usually thought, but the densities of Stoner states for only a few interband transitions. Which transitions are important depends ultimately on how strongly umklapp processes couple the corresponding bands. This allows us to show, in particular, that the Stoner peak in SPEELS spectra does not necessarily indicate the value of the exchange splitting energy. Thus, the common assumption that this peak allows us to estimate the magnetic moment through its correlation with exchange splitting should be reconsidered, both in bulk and surface studies. Furthermore, we are able to show that the above mechanism is one of the main causes for the typical broadness of experimental spectra. Finally, our model predicts that optical spin waves should be excited in SPEELS experiments.Comment: 11 pages, 7 eps figures, REVTeX fil

Nitridation of InP(1 0 0) surface studied by synchrotron radiation

The nitridation of InP(1 0 0) surfaces has been studied using synchrotron radiation photoemission. The samples were chemically cleaned and then ion bombarded, which cleaned the surface and also induced the formation of metallic indium droplets. The nitridation with a Glow Discharge Cell (GDS) produced indium nitride by reaction with these indium clusters. We used the In 4d and P 2p core levels to monitor the chemical state of the surface and the coverage of the species present. We observed the creation of In-N and P-N bonds while the In-In metallic bonds decrease which confirm the reaction between indium clusters and nitrogen species. A theoretical model based on stacked layers allows us to assert that almost two monolayers of indium nitride are produced. The effect of annealing on the nitridated layers at 450 $^\circ$C has also been analysed. It appears that this system is stable up to this temperature, well above the congruent evaporation temperature (370 $^\circ$C) of clean InP(1 0 0): no increase of metallic indium bonds due to decomposition of the substrate is detected as shown in previous works [L. Bideux, Y. Ould-Metidji, B. Gruzza, V. Matolin, Surf. Interface Anal. 34 (2002) 712] studying the InP(1 0 0) surfaces

Release and Clearance Mechanisms of Cardiac Troponin

Myocardial infarction (MI) is often suspected when a patient presents with chest pain. MI is defined as cardiac necrosis due to ischemia, most often mediated through impaired coronary perfusion. Cardiac necrosis results in the release of myoglobin, creatine kinase and cardiac troponin (cTn) to the circulation. According to current guidelines, the MI diagnosis is, to a large extent, based on the patient’s levels of cTn. This thesis examines the mechanisms of cTn release and subsequent clearance from the circulation. The trimeric cardiac troponins, troponin T (cTnT), troponin I (cTnI) troponin C (cTnC), bind to each other and via cTnT to insoluble filaments in the cardio¬myocyte. Contrary to the prevailing opinion we found that a large fraction of cTnT could be released in 37°C plasma from necrotic human cardiac tissue without degradation of insoluble filaments. In contrast to myoglobin, which lacks affinity for cardiac tissue, the release of cTnT was highly plasma volume-dependent, which could explain the delayed clearance of cTnT observed in patients with MI. We then examined the clearance of cTnT from the circulation by injecting cardiac extracts containing both myoglobin and cTnT in rats. We also examined the renal extraction of circulating cTnT by comparing the cTnT concentration in blood samples from the renal vein and an artery in heart failure patients. We found high renal extraction of cTnT and that correction for renal clearance makes the cTnT analysis slightly better at finding patients with an MI in the emergency ward. We next examined the difference in release and clearance of cTnT and cTnI using the currently most frequently used clinical assays. We found that most cTnT and cTnI released from human cardiac tissue were degradation products produced by tissue-resident proteases. We also found that cTnI was degraded and released much faster than cTnT, whereas their subsequent clearance, once they reached the circulation, did not differ between cTnT and cTnI in either rats or humans. Our data potentially explain why cTnI reaches higher levels and disappears faster than cTnT in patients with MI

Layered Semiconductors and Related Systems

The general properties of the layered transition metal dichalcogenides and the possibility to modify these materials by intercalation are reviewed. Examples are given of experimental results obtained by using angle-resolved photoelectron spectroscopy and very-low-energy electron diffraction. The possibility to use layered semiconductors as model systems in studies of e.g. Schottky barriers and surface photovoltage is exemplified by the Rb/WSe$\text{}_{2}$ system. Attention is also paid to the use of van der Waals epitaxy in interface studies, and its possible practical applications. The potential of layered semiconductors like WSe$\text{}_{2}$ in solar cell applications is also mentioned

Determination of the uncertainty of typical airborne sound-measurements on automobile components

Measurements are performed daily in engineering praxis and the results often serve as a basis for the further development of products or business strategies. However, a measurement result is not complete without the statement of the measurement uncertainty since it provides information about the quality of the result and the measurement method. It makes it possible to estimate how reliable the results are. The purpose of this thesis is to find methods to determine the measurement uncertainty of common acoustic measurements for the development of automobile engine components as implemented in the international standard “Guide to the expression of Uncertainty in Measurement”. The measurements are restricted to airborne sound emission and the determination of the sound pressure level and the sound power level. The aim was to describe the methods for the determination of the measurement uncertainty generally, in order to be adapted to several products and test methods. It was realised partly by collecting information from manuals, standards and reports from earlier investigations and partly from performing measurements. There are several reasons for measurement uncertainty and they are either of random or systematic character. Random errors arise from unpredictable variations of influence quantities such as variations in temperature or atmospheric air pressure. Systematic errors always appear with the same size and sign in every measurement and are therefore possible to correct to some extent. They may among other things be caused by zero point deviation of the measurement equipment. The measurements were performed on already existing acoustics test-rigs for the determination of the sound pressure level of a high pressure pump respectively the determination of the sound power level of a fuel injector. The two measurements have several uncertainty components in common but also specific characteristics and together they form a good example on how the uncertainty can be determined. To start, all possible influences on the measurement result were listed and divided into four categories of uncertainties due to: environmental influences, the measurement equipment, the measurement set up and the data processing. The quantity to be measured was then described as a function of the result of the measurement and corrections of each possible variable that may have influenced the result. In most cases the correction could be set to zero, but the uncertainty of this setting was used to estimate the total uncertainty of the quantity. With this method it is possible to individually consider each component of the total measurement uncertainty. To know how the total uncertainty is composed makes it easier to improve the measurement method and make it more accurate. The results showed that the uncertainty due to the room and reflections from the wall and the uncertainty due to the mounting of the source contributed the most to the total uncertainty. These are difficult to reduce without modifying the measurement test-rig.Validerat; 20101217 (root