Experimental investigation and CFD simulation of horizontal stratified two-phase flow phenomena

For the investigation of stratified two-phase flow, two horizontal channels with rectangular cross-section were built at Forschungszentrum Dresden-Rossendorf (FZD). The channels allow the investigation of air/water co-current flows, especially the slug behaviour, at atmospheric pressure and room temperature. The test-sections are made of acrylic glass, so that optical techniques, like high-speed video observation or particle image velocimetry (PIV), can be applied for measurements. The rectangular cross-section was chosen to provide better observation possibilities. Moreover, dynamic pressure measurements were performed and synchronised with the high-speed camera system.CFD post-test simulations of stratified flows were performed using the code ANSYS CFX. The Euler–Euler two fluid model with the free surface option was applied on grids of minimum 4 × 10⁵ control volumes. The turbulence was modelled separately for each phase using the k–ω-based shear stress transport (SST) turbulence model. The results compare very well in terms of slug formation, velocity, and breaking. The qualitative agreement between calculation and experiment is encouraging and shows that CFD can be a useful tool in studying horizontal two-phase flow.     

Occult tumor cells of malignant melanoma and consequences for surgical treatment

Immediate and complete surgical excision is the standard mode of treatment for primary malignant melanoma. There is still a controversy about the adequate resection margins. In this study we looked for microscopic satellites in order to estimate the extent of local therapy. METHOD: 19 patients with malignant melanoma of the trunk or extremities, treated by wide excision, were included. Clinical courses were documented. Postoperative follow-up was 1.4 years in the mean. In primary tumours and cutaneous excisions we looked for microscopic satellites with routine histology and immunohistochemistry (APAAP-technique, monoclonal antibody HMB-45). RESULTS: Using APAAP-technique in combination with routine histology, we could show that microscopic satellites only occurred in specimens of melanomas of more than 5 mm thickness. In the two cases where evident microscopic satellites were present a systemic dissemination obviously evolved already before the first surgical treatment. Therefore, in those cases wide resection margins do not provide an increasing chance of survival. CONCLUSION: The idea to remove microscopic satellites by wide surgical excisions and thus to reduce the risk for systemic dissemination and local recurrence cannot be supported.     

The metrics of spatial situation models.

The authors investigated the metrics of spatial distance represented in situation models of narratives. In 3 experiments, a spatial gradient of accessibility in situation models was observed: The accessibility of objects contained in the situation model decreased with increasing spatial distance between the object and the reader's focus of attention. The first 2 experiments demonstrated that this effect of spatial distance was purely categorical rather than Euclidean: Accessibility depended on the number of rooms located between the object and the focus of attention, not on the size of the rooms. Experiment 3 revealed, however, that participants were able to use information about Euclidean distance in a secondary task when necessary. The implications of these results for theories of narrative comprehension and hierarchical versus nonhierarchical theories of spatial memory are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

I'm home: Defining and evaluating a gesture set for smart-home control

Mobile phones seem to present the perfect user interface for interacting with smart environments, e.g. smart-home systems, as they are nowadays ubiquitous and equipped with an increasing amount of sensors and interface components, such as multi-touch screens. After giving an overview on related work this paper presents the adapted design methodology proposed by Wobbrock et al. (2009) for the development of a gesture-based user interface to a smart-home system. The findings for the new domain, device and gesture space are presented and compared to findings by Wobbrock et al. (2009). Three additional steps are described: A small pre-test survey, a mapping and a memory test and a performance test of the implemented system.This paper shows the adaptability of the approach described by Wobbrock et al. (2009) for three-dimensional gestures in the smart-home domain. Elicited gestures are described and a first implementation of a user interface based on these gestures is presented.     

A silicon condenser microphone with structured back plate and silicon nitride membrane

The fabrication process of a silicon condenser microphone and experimental results of the acoustic measurements are described. The microphone consists of two chips. One chip carries the 150 nm thick silicon nitride membrane, which has an area of 0.8 mm × 0.8 mm. The second chip contains the back electrode, the spacer and the contact pads of the microphone. In order to reduce the streaming resistances in the air gap, the back-electrode area is either structured with grooves by a plasma etching technique or with holes by an anisotropic etching technique. A frequency-independent sensitivity of 10 mV/Pa (open circuit, 1.8 mV/Pa measured) up to 30 kHz is obtained as a result of this structuring of the back-electrode area. Since the air-gap height is only 2 μm, the capacitance of the transducers ranges from 1 to 1.3 pF. The total size of the silicon microphone is 1.6 mm × 2 mm × 0.56 mm.     

Acute and chronic neutral endopeptidase inhibition in rats with aortocaval shunt

In heart failure, sodium and water retention develop despite elevated plasma levels of atrial natriuretic peptide. Atrial natriuretic peptide is degraded in part by a neutral endopeptidase. Whether neutral endopeptidase inhibition improves sodium and water excretion in heart failure is unknown. We determined the effect of neutral endopeptidase inhibition on plasma levels of atrial natriuretic peptide and the renal response to acute volume expansion in rats with aortocaval shunts and in sham-operated controls. Acute endopeptidase inhibition with SQ 28,603 (30 mg/kg) elevated atrial natriuretic peptide plasma levels in both shunted rats (523 +/- 54 to 1258 +/- 330 pmol/L, P<.05) and controls (184 +/- 28 to 514 +/- 107 pmol/L, P<.05). Urinary cGMP excretion, which reflects renal action, increased in parallel. However, the diuretic and natriuretic responses to acute volume expansion were enhanced only in control rats and not in shunted rats. In contrast to the acute effects, chronic neutral endopeptidase inhibition with SCH 34826 (30 mg/kg twice daily) in shunted rats did not change atrial natriuretic peptide plasma levels or cGMP excretion. Nevertheless, the diuretic and natriuretic responses to acute volume load were increased by chronic endopeptidase inhibition in shunted rats (1789 +/- 154 to 2674 +/- 577 microL/80 min and 99 +/- 31 to 352 +/- 96 micromol/80 min, respectively; P<.05). Chronic endopeptidase inhibition attenuated the cardiac hypertrophic response to aortocaval shunt without changing arterial blood pressure. Our data show that the renal effects of neutral endopeptidase inhibition are not necessarily dependent on changes in atrial natriuretic peptide plasma levels but instead may be mediated by local inhibition of the neutral endopeptidase in the kidney. In addition, chronic endopeptidase inhibition may attenuate heart failure-induced cardiac hypertrophy independent of hemodynamic effects.     

Role of agglomeration in the early stages of papillar stone formation

Possible effects of crystal agglomeration on the early stages of calcium oxalate papillar stone formation are evaluated. The collecting ducts are filled with liquid that flows laminarly as established through hydrodynamical and physicochemical considerations. Under such conditions, agglomeration due to laminar shear forces proceeds. Agglomeration of calcium oxalate monohydrate crystals present in urine at a concentration typical for clinically observed crystalluria cannot result in the formation of a particle sufficiently large enough to be retained in the Bellini's duct and become a papillar stone nidus (nucleus). Formation of such an aggregate during the passage time of urine through the duct requires an unrealistically high concentration of crystals in urine, one that exceeds the normal content of urinary oxalate by several orders of magnitude. Aggregates obstructing the Bellini's duct as assumed in the free particle theory cannot represent a major factor in stone formation. This conclusion is corroborated by experimental results and other observations.     

Oriented growth of silicide and carbon in SiC-based sandwich structures with nickel

We report on the formation kinetics and the metal-mediated structuring in nanoregions of silicide and carbon containing interlayers in SiC-based materials. The silicide formation and the graphite texturisation are determined by complex reactive diffusion processes. High resolution and analytical electron microscopy evidenced a δ-Ni₂Si growth with a 5 0 6 fibre texture in parallel orientation to the 0 0 0 1 direction of the SiC substrate. The oriented growth of graphitic regions in the silicide hints to a diffusion controlled carbon precipitation from the silicide supersaturated with carbon, explaining the observed orientation relationships between graphite and silicon carbide: perpendicular and parallel to the {0 0 0 1} silicon carbide surfaces.     

Impact of Ferroelectric Layer Thickness on Reliability of Back-End-of-Line-Compatible Hafnium Zirconium Oxide Films

Due to its ferroelectricity, hafnium oxide has attracted a lot of attention for ferroelectric memory devices. Amongst different dopant elements, zirconium is found to be beneficial due to the relatively low crystallization temperature of hafnium-zirconium-oxide (HZO), thus it is back-end-of-line (BEoL) compatible. The thickness of HZO has a significant impact on ferroelectric device reliability. High operation temperatures and high endurance are important criteria depending on the application. Herein, various HZO thicknesses (7, 8, and 10 nm) in MFM (metal-ferroelectric-metal) capacitors are investigated at varying operation temperatures (25 to 175 °C) at varying electric fields (±3 to ±5.4 MV cm⁻¹) with respect to polarization, leakage current, endurance, and retention. 7 nm HZO showed promising results with an endurance of 10⁷ cycles, with a low leakage current density, and almost no retention loss after 10 years. Extrapolated results at operation conditions (±2 MV cm⁻¹ and 10 MHz) showed an endurance of 10¹⁰ cycles.