Warmzug- und Zug-Kriechversuche an reaktionsgesintertem Siliziumnitrid

Elevated Temperature Tensile and Tensile Creep Tests of Reaction-Bonded Silicon Nitride Design and construction of a tensile testing device is described for short tensile testing and creep tensile testing of ceramic materials in the temperature range for room temperature up to 1500 °C in open air. Super imposed bending and the avoidance of it is emphasized. Results are reported of tensile tests on isostatically pressed RB-SN of different densities in dependence of test temperature. Also creep behavior in tensile and flexural tests is compared at temperatures of 1200 °C, 1250 °C and 1400 °C in open air.     

加速器二极磁体的应力和磁场分析

在本论文中,我们发展了磁机械耦合的ANSYS分析方法,使用有限元方法研究了加速器二极磁体的应力特性,通过数值模拟,我们研究了超导加速器磁体在磁体装配,冷却和运行磁场为2T时的应力。研究的结果将用于评估超导加速器磁体在建造和运行时的应力控制。     

Neurochemical Monitoring of Traumatic Brain Injury by the Combined Analysis of Plasma Beta-Synuclein,NfL, and GFAP in Polytraumatized Patients

Traumatic brain injury (TBI) represents a major determining factor of outcome in severely injured patients. However, reliable brain-damage-monitoring markers are still missing. We therefore assessed brain-specific beta-synuclein as a novel blood biomarker of synaptic damage and measured the benchmarks neurofilament light chain (NfL), as a neuroaxonal injury marker, and glial fibrillary acidic protein (GFAP), as an astroglial injury marker, in patients after polytrauma with and without TBI. Compared to healthy volunteers, plasma NfL, beta-synuclein, and GFAP were significantly increased after polytrauma. The markers demonstrated highly distinct time courses, with beta-synuclein and GFAP peaking early and NfL concentrations gradually elevating during the 10-day observation period. Correlation analyses revealed a distinct influence of the extent of extracranial hemorrhage and the severity of head injury on biomarker concentrations. A combined analysis of beta-synuclein and GFAP effectively discriminated between polytrauma patients with and without TBI, despite the comparable severity of injury. Furthermore, we found a good predictive performance for fatal outcome by employing the initial plasma concentrations of NfL, beta-synuclein, and GFAP. Our findings suggest a high diagnostic value of neuronal injury markers reflecting distinct aspects of neuronal injury for the diagnosis of TBI in the complex setting of polytrauma, especially in clinical surroundings with limited imaging opportunities.     

Rotations in Excited ICT States – Fluorescence and its Microenvironmental Sensitivity

Fluorescence spectroscopy as an analytical tool for various applications as well as fluorescence probes showing a sensitive behavior towards their microenvironmental properties have experienced an increasing interest in research in the last decades. Recently our group has contributed to this field of interest by introducing a novel mechanism where a planarization in the excited state occurs leading to an advantageous allowed emission. Here, we provide an overview of intramolecular charge transfer states where a rotation in the excited state causes a high sensitivity for microenvironmental changes. Furthermore, effects which influence the surroundings of the fluorophores are described in detail. Recent results where t wisted i ntramolecular c harge t ransfer (TICT) and a ggregation- i nduced e mission (AIE) effects were combined are described and a promising outlook for further research progress is provided.     

High precision processing of flexible P3HT/PCBM modules with geometric fill factor over 95%

Flexible OPV modules, based on P3HT:PCBM as absorber layer, were manufactured with a power conversion efficiency over 3% and for a total area of 3500 mm² consisting of 14 in series interconnected cells. The modules utilize the excellent mechanical and the outstanding optical properties of sputtered transparent ITO-Metal-ITO (IMI) electrodes deposited on the PET foil on the one hand, and the combination of large area slot-die coating with high resolution ultrafast laser patterning on the other hand. The manufacturing of modules with outstanding performance was found to be reproducible. The right combination of innovative electrodes and smart roll-to-roll compatible processing technologies demonstrates a viable path towards high efficient industrial module technology.     

Asymptotic Bethe-Ansatz results for a Hubbard chain with 1/sinh-hopping

We investigate spin-1/2 electrons with local Hubbard interaction and variable range hopping amplitudes which decay like sinh()/sinh(r). Using Sutherland's Asymptotic Bethe Ansatz we derive the generalized Lieb-Wu integral equations from the two-particle phase shift. For half-filling we obtain a closed expression for the ground state energy density. Due to the nesting property there is a metal-to-insulator transition at U_c(> > 0) = 0⁺.In the singular limit = 0the charge gap opens when the interaction strength equals the bandwidth, U _c( = 0) =W.We would like to thank P. Nozières and A. Gogolin for stimulating discussions. F. G. thanks all his colleagues at the ILL Grenoble for their kind hospitality during a stay in 1993/94.     

Effect of temperature on the creep behavior of a Ni–Cr–Fe–Al alloy: a comparison of the experimental data and a model

In order to characterise the mechanical behaviour of sandwich structures, which combine an interlayer of a woven wire mesh between two thin walled sheet metals, creep tests at 650, 680 and 750 °C were carried out on sheet metals made of the nickel based alloy Nicrofer 6025 HT (2.4633). In addition to the tests the creep behaviour was simulated by a model, which considers the creep rate as a function of the applied stress σ and the internal deformation resistance including an internal back stress σ_i and a particle resistance σ_P. The damage is included by a damage parameter D, which converges to “one” with increasing damage. A concluding comparison with the creep test results shows that the model is able to describe the creep behaviour of the investigated sheet metals.     

Comparison of four motion correction techniques in SPECT imaging of the heart: a cardiac phantom study

The aim of this study was to evaluate the accuracy of four different motion correction techniques in SPECT imaging of the heart. METHODS: We evaluated three automated techniques: the cross-correlation (CC) method, diverging squares (DS) method and two-dimensional fit method and one manual shift technique (MS) using a cardiac phantom. The phantom was filled with organ concentrations of 99mTc closely matching those seen in patient studies. The phantom was placed on a small sliding platform connected to a computer-controlled stepping motor. Linear, random, sinusoidal and bounce motions of magnitude up to 2 cm in the axial direction were simulated. Both single- and dual-detector 90 degrees acquisitions were acquired using a dual 90 degrees detector system. Data were acquired over 180 degrees with 30 or 15 frames/detector (single-/dual-head) at 30 sec/frame in a 64x64 matrix. RESULTS: The simulated single-detector system, CC method, failed to accurately correct for any of the simulated motions. The DS technique overestimated the magnitude of phantom motion, particularly for images acquired between 45 degrees left anterior oblique and 45 degrees left posterior oblique. The two-dimensional and MS techniques accurately corrected for motion. The simulated dual 90 degrees detector system, CC method, only partially tracked random or bounce cardiac motion and failed to detect sinusoidal motion. The DS technique overestimated motion in the latter half of the study. Both the two-dimensional and MS techniques provided superior tracking, although no technique was able to accurately track the rapid changes in cardiac location simulated in the random motion study. Average absolute differences between true and calculated position of the heart on single- and dual 90 degrees -detectors were 1.7 mm and 1.5 mm for the two-dimensional and MS techniques, respectively. The corresponding values for the DS and CC techniques were 5.7 and 8.9 mm, respectively. CONCLUSION: Of the four techniques evaluated, manual correction by an experienced technologist proved to be the most accurate, although results were not significantly different from those observed with the two-dimensional method. Both techniques accurately determined cardiac location and permitted artifact-free reconstruction of the simulated cardiac studies.     

Injector Quantum Dot Molecule Infrared Photodetector: A Concept for Efficient Carrier Injection

Nano-Micro Letters - Quantum dot infrared photodetectors are expected to be a competitive technology at high operation temperatures in the long and very long wavelength infrared spectral range....