Search for a dark matter annihilation signal from the galactic center halo with H.E.S.S

A search for a very-high-energy (VHE; ≥100 GeV) γ-ray signal from self-annihilating particle dark matter (DM) is performed towards a region of projected distance r～45-150 pc from the Galactic center. The background-subtracted γ-ray spectrum measured with the High Energy Stereoscopic System (H.E.S.S.) γ-ray instrument in the energy range between 300 GeV and 30 TeV shows no hint of a residual γ-ray flux. Assuming conventional Navarro-Frenk-White and Einasto density profiles, limits are derived on the velocity-weighted annihilation cross section (σv) as a function of the DM particle mass. These are among the best reported so far for this energy range and in particular differ only little between the chosen density profile parametrizations. In particular, for the DM particle mass of ～1 TeV, values for (σv) above 3×10(-25) cm(3)?s(-1) are excluded for the Einasto density profile.     

Evidence for cluster shape effects on the kinetic energy spectrum in thermionic emission

Experimental kinetic energy release distributions obtained for the thermionic emission from C(n) (-) clusters, 10< or =n< or =20, exhibit significant non-Boltzmann variations. Using phase space theory, these different features are analyzed and interpreted as the consequence of contrasting shapes in the daughter clusters; linear and nonlinear isomers have clearly distinct signatures. These results provide a novel indirect structural probe for atomic clusters associated with their thermionic emission spectra.     

Application of Deep Learning Workflow for Autonomous Grain Size Analysis

Traditional grain size determination in materials characterization involves microscopy images and a laborious process requiring significant manual input and human expertise. In recent years, the development of computer vision (CV) has provided an alternative approach to microstructural characterization with preliminary implementations greatly simplifying the grain size determination process. Here, an end-to-end workflow to measure grain size in microscopy images without any manual input is presented. Following the ASTM standards for grain size determination, results from the line intercept (Heyn’s method) and planimetric (Saltykov’s method) approaches are used as the baseline. A pre-trained holistically nested edge detection (HED) model is used for CV-based edge detection, and the results are further compared to the classic Canny edge detection method. Post-processing was performed using open-source image processing packages to extract the grain size. In optical microscope images, the pre-trained HED model achieves much higher accuracy than the Canny edge detection method while reducing the image processing time by one to two orders of magnitude compared to traditional methods. The effects of morphological operations on the predicted grain size accuracy are also explored. Overall, the proposed end-to-end convolutional neural network (CNN)-based workflow can significantly reduce the processing time while maintaining the same accuracy as the traditional manual method.     

Einfache Verfahren zur Analyse von Kakao, Schokolade und Milchschokolade

Ohne Zusammenfassung     

Zum Blutnachweis

Ohne Zusammenfassung     

Zur Bestimmung des Alkohols

Ohne Zusammenfassung     

pK a Constant Determination of Two Triazole Pesticides: Tebuconazole and Penconazole

We determined the acidity constants of tebuconazole and penconazole, two fungicides from the group of 1,2,4-triazoles. Potentiometric titrations were performed in a 20 % (v/v) acetonitrile/water mixture at 25 °C and at a fixed ionic strength (KNO₃, 0.1 mol·dm^?3). The pK _a values (representing thermodynamic constants) were determined to be 5.0 ± 0.1 and 5.2 ± 0.1 for tebuconazole and penconazole, respectively. These values could be used in pure water solutions to consider the protonated or deprotonated forms when studying the field behavior of these fungicides. Molecular modeling calculations allowed identifying the N4 atom as the protonation site.     

Use of an annular241Am−Be neutron source for INAA of some major constituents in large samples

An annular neutron source offers the possibility of positioning a large sample, surrounded by a paraffin thermalizing shield, inside the central tube. The optimal shield/sample ratio is determined experimentally. The absolute value of the thermal neutron flux is determined by irradiating NaHCO₃ and evaluating the induced²⁴Na-activity by the sumpeak method. Average fluxes over the seven irradiation capsules are presented. Some current applications are discussed.