On the dc Magnetization, Spontaneous Vortex State and Specific Heat in the superconducting state of the weakly ferromagnetic superconductor RuSr2_{2}GdCu2_{2}O8_{8}

Magnetic-field changes $<$ 0.2 Oe over the scan length in magnetometers that necessitate sample movement are enough to create artifacts in the dc magnetization measurements of the weakly ferromagnetic superconductor RuSr$_{2}$GdCu$_{2}$O$_{8}$ (Ru1212) below the superconducting transition temperature $T_{c} \approx$ 30 K. The observed features depend on the specific magnetic-field profile in the sample chamber and this explains the variety of reported behaviors for this compound below $T_{c}$. An experimental procedure that combines improvement of the magnetic-field homogeneity with very small scan lengths and leads to artifact-free measurements similar to those on a stationary sample has been developed. This procedure was used to measure the mass magnetization of Ru1212 as a function of the applied magnetic field H (-20 Oe $\le$ H $\le$ 20 Oe) at $T < T_{c}$ and discuss, in conjunction with resistance and ac susceptibility measurements, the possibility of a spontaneous vortex state (SVS) for this compound. Although the existence of a SVS can not be excluded, an alternative interpretation of the results based on the granular nature of the investigated sample is also possible. Specific-heat measurements of Sr$_{2}$GdRuO$_{6}$ (Sr2116), the precursor for the preparation of Ru1212 and thus a possible impurity phase, show that it is unlikely that Sr2116 is responsible for the specific-heat features observed for Ru1212 at $T_{c}$.Comment: 17 pages, 6 figure

H2AX phosphorylation screen of cells from radiosensitive cancer patients reveals a novel DNA double-strand break repair cellular phenotype

BACKGROUND: About 1-5% of cancer patients suffer from significant normal tissue reactions as a result of radiotherapy (RT). It is not possible at this time to predict how most patients' normal tissues will respond to RT. DNA repair dysfunction is implicated in sensitivity to RT particularly in genes that mediate the repair of DNA double-strand breaks (DSBs). Phosphorylation of histone H2AX (phosphorylated molecules are known as gammaH2AX) occurs rapidly in response to DNA DSBs, and, among its other roles, contributes to repair protein recruitment to these damaged sites. Mammalian cell lines have also been crucial in facilitating the successful cloning of many DNA DSB repair genes; yet, very few mutant cell lines exist for non-syndromic clinical radiosensitivity (RS).\ud \ud METHODS: Here, we survey DNA DSB induction and repair in whole cells from RS patients, as revealed by gammaH2AX foci assays, as potential predictive markers of clinical radiation response.\ud \ud RESULTS: With one exception, both DNA focus induction and repair in cell lines from RS patients were comparable with controls. Using gammaH2AX foci assays, we identified a RS cancer patient cell line with a novel ionising radiation-induced DNA DSB repair defect; these data were confirmed by an independent DNA DSB repair assay.\ud \ud CONCLUSION: gammaH2AX focus measurement has limited scope as a pre-RT predictive assay in lymphoblast cell lines from RT patients; however, the assay can successfully identify novel DNA DSB repair-defective patient cell lines, thus potentially facilitating the discovery of novel constitutional contributions to clinical RS

Roentgentarget und Verfahren zur Erzeugung von Roentgenstrahlung

DE 102009007871 A1 UPAB: 20100903 NOVELTY - The target (20) has a target material (2) and an electrically-conductive hollow substrate (1) that are made of foamed material. The substrate is made of metal or ceramic. The substrate has a fluid-sealed outer surface that comprises a cooling medium supply opening and cooling medium removal opening. The substrate forms a rotationally symmetric body with a rotational axis. The target material is in the form of a circular target strip and provided at an outer surface of the rotationally symmetric body. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following: (1) an X-ray tube comprising an electron gun (2) a method for producing an X-ray. USE - X-ray target i.e. reflection X-ray target, for use in an X-ray tube (claimed) in a Roentgen system. Uses include but are not limited to non destructive testing applications of material, in medical field, in luggage inspection field and for analysis purpose. ADVANTAGE - The substrate made of foamed material serves as a foamed cooling body, thus enabling dissipation of remaining heat arising during production of X-ray in a better manner

Concept for a nanometer-resolution X-ray computed tomography system for non-destructive testing based on room temperature semiconductor detector modules

In the nanotechnology sector there is a strong need for non-destructive testing instruments that can reveal the inner structure of objects. For such applications we developed a concept for a novel nanometer-resolution X-ray computed tomography (CT) system, which does not rely on the use of X-ray optics. We target a resolution in the range of existing nano CT setups (50 to 150 nm) while increasing the field-of-view by an order of magnitude. Our calculations on the performance of the planned system give promising results. We present possible design goals, such as spatial resolution, object size and show typical limits (source intensity, power, pixel pitch, etc.) for such a system. The fundamentals for calculations to obtain estimates on the system parameters are discussed. The required detector and system properties, including focus-to-object and focus-to-detector distances and resulting measurement times for this approach and their relations are shown. On this basis, a f easible concept for the measurement system is proposed. Currently, large-area, high-resolution detectors with suitable properties, like dynamic range especially at low flux and efficiency, are not yet commercially available. The detector will be based on photon counting room temperature semiconductor detector modules that are currently available. A concept for the arrangement of multiple detector modules that are not four-side tileable is presented. A solution for coping with the resulting gaps for X-ray CT applications is illuminated. In summary this paper discusses the results and perspectives based on the emerging possibilities of the planned system

Röntgentarget und ein Verfahren zur Erzeugung von Röntgenstrahlen

An X-ray target (110) for producing X-radiation (120) by way of an electron beam (130) striking the X-ray target (110) has a cross-sectional area (A) perpendicular to the electron beam (130) and a longitudinal extent (L) parallel to the electron beam (130), wherein the electron beam (130) can be directed onto the cross-sectional area (A) and A 2