Evaluation of MR-induced hot spots for different temporal SAR modes using a time-dependent finite difference method with explicit temperature gradient treatment

An investigation of magnetic resonance (MR)-induced hot spots in a high-resolution human model is performed, motivated by safety aspects for the use of MR tomographs. The human model is placed in an MR whole body resonator that is driven in a quadrature excitation mode. The MR-induced hot spots are studied by varying the following: (1) the temporal specific absorption rate (SAR) mode ("steady imaging", "intermittent imaging"), (2) the simulation procedure (related to given power levels or to limiting temperatures), and (3) different thermal tissue properties including temperature-independent and temperature-dependent perfusion models. Both electromagnetic and thermodynamic simulations have been performed. For the electromagnetic modeling, a commercial finite-integration theory (FIT) code is applied. For the thermodynamic modeling, a time-domain finite-difference (FD) scheme is formulated that uses an explicit treatment of temperature gradient components. This allows a flux-vector-based implementation of heat transfer boundary conditions on cubical faces. It is shown that this FD scheme significantly reduces the staircase errors at thermal boundaries that are locally sloped or curved with respect to the cubical grid elements.     

Dirty RF: A New Paradigm

The implementation challenge for new low-cost low-power wireless modem transceivers has continuously been growing with increased modem performance, bandwidth, and carrier frequency. Up to now we have been designing transceivers in a way that we are able to keep the analog (RF) problem domain widely separated from the digital signal processing design. However, with today’s deep sub-micron technology, analog impairments – “dirt effects” – are reaching a new problem level which requires a paradigm shift in the design of transceivers. Examples of these impairments are phase noise, non-linearities, I/Q imbalance, ADC impairments, etc. In the world of “Dirty RF” we assume to design digital signal processing such that we can cope with a new level of impairments, allowing lee-way in the requirements set on future RF sub-systems. This paper gives an overview of the topic and presents analytical evaluations of the performance losses due to RF impairments as well as algorithms that allow to live with imperfect RF by compensating the resulting error effects using digital baseband processing.     

Evidence for Glass–glass Interfaces in a Columnar Cu–Zr Nanoglass

Comprehensive analyses of the atomic structure using advanced analytical transmission electron microscopy-based methods combined with atom probe tomography confirm the presence of distinct glass–glass interfaces in a columnar Cu-Zr nanoglass synthesized by magnetron sputtering. These analyses provide first-time in-depth characterization of sputtered film nanoglasses and indicate that glass–glass interfaces indeed present an amorphous phase with reduced mass density as compared to the neighboring amorphous regions. Moreover, dedicated analyses of the diffusion kinetics by time-of-flight secondary ion mass spectroscopy (ToF SIMS) prove significantly enhanced diffusivity, suggesting fast transport along the low density glass–glass interfaces. The present results further indicate that sputter deposition is a feasible technique for reliable production of nanoglasses and that some of the concepts proposed for this new class of glassy materials are applicable.     

A Mapping Framework Based on Packing for Design Space Exploration of Heterogeneous MPSoCs

The computational demand of signal processing algorithms is rising continuously. Heterogeneous embedded multiprocessor systems-on-chips are one solution to satisfy this demand. But to be able to take advantage of these systems, new strategies are required to map applications to such a system and to evaluate the systems performance at a very early design stage. We will present a framework for static, analytical, bottom-up temporal and spatial mapping of applications to MPSoCs based on packing. This mapping framework allows easy performance evaluation and design space exploration of heterogeneous systems on chip.

Zum Aroma von Speisepilzen

Zusammenfassung Kopfraum-Proben, Wasserdampfdestillate und Dichlormethanextrakte der beliebtesten Speisepilze Champignon (Agaricus campestris undAgaricus bisporus), Parasol (Riesenschirmpilz,Lepiota procera), Hallimasch (Armillaria mellea), Steinpilz (Herrenpilz,Boletus edulis) und Pfifferling (Eierschwamm,Cantharellus cibarius) wurden mittels GC/FID, GC/FTIR/MS und GC-Sniffing-Technik untersucht. Ziel dieser Untersuchungen war es, die für den typischen Duft der einzelnen Pilzarten verantwortlichen Inhaltsstoffe zu identifizieren. Um Daten aus GC/FTIR/MS-Messungen mit olfactorischen Daten direkt vergleichen zu können, wurde die GC-Sniffing-Technik verwendet. Die Ergebnisse, besonders solche von Kopfraumproben, zeigten, daß 1-Octen-3-o1, ein bekannter Pilzduftstoff, von grundlegender Bedeutung für die Kopfnote der untersuchten Pilze ist. Mehr als 70 Einzelkomponenten tragen qualitativ und quantitativ zum Gesamtgeruchseindruck der einzelnen Arten bei, wobei besonders C₈-Derivate in signifikanter Weise den Duft der meisten Kopfraumproben beeinflussen. Carbonylverbindungen und Ester (C₄-C₁₄) dagegen spielen eine wesentliche Rolle (z. B. Anisaldehyd in Champignonproben) vor allem in den Wasserdampfdestillations- und Extraktproben.

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The aroma of edible mushrooms. Headspace analysis using GC/FID and GC/FTIR/MS

Headspace samples, steam distillates and dichloromethane extracts of the most well liked edible mushrooms (Agaricus campestris, Agaricus bisporus, Lepiota procera, Armillaria mellea, Boletus edulis and Cantharellus cibarius) were investigated by means of GC/FID, GC/FTIR/MS and a GC-sniffing technique. The aim of these analyses was the identification of constituents responsible for the typical mushroom odour of each species. To relate GC/Fouriertransform Infrarot-Detektor/MS (GC/FTIR/MS) data with olfactoric ones, the GC-sniffing technique was used. The results, especially of the headspace samples, showed that 1-octen-3-ol, a well-known mushroom aroma compound, is of basic importance for the top note of the investigated mushrooms. More than seventy constituents that additionally have an effect (qualitatively and quantitatively) on the odour impression of these species were identified. Among them especially C₈-derivatives contribute in a significant way to the headspace odour of most of the samples. Carbonyls and esters (C₄-C₁₄) on the other hand play an important role (e.g. anisaldehyde inAgaricus samples) more in the steam distillate and extract samples.

     

Aroma von Wei?weinblüten: Korrelation sensorischer Daten mit Headspace-Inhaltsstoffen

Zusammenfassung Mittels Headspace-Analyse in Kombination mit gaschromatographisch-spektroskopischen Methoden (GC-FID und GC-FTIR-MS), sowie der GC-Schnüffel-Technik gelang es, Blüten verschiedener Weinsorten (sieben verschiedene Weißweinspecies) anhand der Duftstoff-Zusammensetzung bezüglich duftbestimmender Sesquiterpene und duftabrundender Monoterpene im Headspace zu korrelieren.-Alle untersuchten Weinblüten besitzen einen reseda-artigen, schönen, blumigen, staubigen, trockenen, angenehmen, interessanten, grünen, frischen, intensiven und süßen Duft wobei sich die einzelnen Blüten, je nach Weinsorte, lediglich in der Intensität der Einzeldüfte, nicht aber in der Gesamtduftrichtung unterscheiden. Die erstellten Geruchsprofile und die entsprechenden multivariaten Korrelationen dieser Profile zeigten eine weitgehende Übereinstimmung mit jenen Ergebnissen, die aus den Headspace-Inhaltsstoffkorrelationen der einzelnen Blütensorten erhalten werden konnten. -Die Möglichkeiten weiterer Zusammenhänge mit entsprechenden ampelographischen Aspekten der untersuchten Weinsorten werden diskutiert.

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Aroma of white vine blossoms: correlation of sensoric data with headspace constituents

Using headspace-analysis in combination with gaschromatographic-spectroscopic methods (GC-FID and GC-FTIR-MS) as well as with the GC-sniffing-technique it was possible to correlate blossoms of 7 different vine-varieties by means of the composition of odor compounds in their headspace considering only odor-dominant sesquiterpenes and odor-assistant monoterpenes. -All investigated vineblossoms possess a mignonette-like, pleasant, floral, dusty, dry, interesting, green, fresh, intense and sweet odour and with regard to the vine-species they only differ in the intensity of single odournotes, but not in the direction of the total odour. The odour-profiles and the corresponding multivariate data analysis of these profiles showed a significant agreement with those results, which were obtained by correlations of headspace constituents. -The possibility of further connectivities with the corresponding ampelographic aspects of the investigated vine-species is also discussed.

     

Spiral-CT-based assessment of tracheal stenoses using 3-D-skeletonization

PURPOSE: Demonstration of a technique for three-dimensional (3-D) assessment of tracheal-stenoses, regarding site, length and degree, based on spiral computed tomography (S-CT). PATIENTS AND METHODS: S-CT scanning and automated segmentation of the laryngo-tracheal tract (LTT) was followed by the extraction of the LTT medial axis using a skeletonization algorithm. Orthogonal to the medial axis the LTT 3-D cross-sectional profile was computed and presented as line charts, where degree and length was obtained. Values for both parameters were compared between 36 patients and 18 normal controls separately. Accuracy and precision was derived from 17 phantom studies. RESULTS: Average degree and length of tracheal stenoses was found to be 60.5% and 4.32 cm in patients compared with minor caliber changes of 8.8% and 2.31 cm in normal controls (p < 0.0001). For the phantoms an excellent correlation between the true and computed 3-D cross-sectional profile was found (p < 0.005) and an accuracy for length and degree measurements of 2.14 mm and 2.53% respectively could be determined. The corresponding figures for the precision were found to be 0.92 mm and 2.56%. CONCLUSION: LTT 3-D cross-sectional profiles permit objective, accurate and precise assessment of LTT caliber changes. Minor LTT caliber changes can be observed even in normals and, in case of an otherwise normal S-CT study, can be regarded as artifacts.     

Optimized Preparation of Elastically Soft,Highly Piezoelectric,Cellular Ferroelectrets from Nonvoided Poly(ethylene Terephthalate) Films

Electrically charged cellular polymer films can exhibit very high piezoelectric activity and are therefore more and more often employed in advanced electromechanical and electro‐acoustical transducers. In this paper, we report an optimized sequence of steps for preparing such ferroelectrets from commercial nonvoided poly(ethylene terephthalate) (PETP) films by means of foaming with CO₂, biaxial mechanical stretching, controlled void inflation, and bipolar electric charging. The nonvoided PETP films were foamed with supercritical CO₂ at a suitably high pressure and subsequently annealed for stabilization. The cellular foam structure was further optimized by means of well‐controlled biaxial stretching in a commercial stretcher and sometimes subsequent inflation in a pressure chamber. Bipolar electric charging of the internal voids was achieved through the application of high electric fields in an SF₆ atmosphere. The new optimized PETP ferroelectrets exhibit quite large piezoelectric coefficients up to almost 500 pC N^–1, for which unusually low elastic stiffnesses of only around 0.3 MPa are essential. The PETP‐foam ferroelectrets possess unclamped thickness‐extension resonance frequencies between approximately 120 and 250 kHz, and are thus highly suitable for several established as well as novel ultrasonic‐transducer applications.     

Demonstration of the monolithic interconnection on CIS solar cells by picosecond laser structuring on 30 by 30 cm2 modules

In this paper, we present the selective structuring of all three patterns (P1, P2 and P3) of a monolithic interconnection of CIS (Cu(In,Ga)(S,Se)₂) thin film solar cells by picosecond laser pulses at a wavelength of 1064 nm. We show results for single pulse ablation threshold values and line scribing of molybdenum films on glass (P1), CIS on molybdenum (P2) and zinc oxide on CIS (P3). The purposes of these processes are the p‐type isolation (P1), cell interconnect (P2) and n‐type isolation (P3), which are required for complete cell architecture. The half micron thick molybdenum back electrode can be structured with a process speed of more than 15 m/s at about 15 W average power without detectable residues and damage by direct induced laser ablation from the back side (P1). The CIS layer can be structured selectively down to the molybdenum at process speeds up to 1 m/s at about 15 W average power, due to the precision of direct laser ablation in the ultrashort pulse regime (P2). The ZnO front electrode layer is separated by clean trenches with straight side walls at process speeds of up to 15 m/s at about 10 W average power, as a result of indirect induced laser ablation (P3). A validation of functionality of all processes is demonstrated on CIS solar cell modules (30 × 30 cm²). By replacing one state‐of‐the‐art process by a picosecond laser process at a time, solar efficiencies could be increased for P1 and P2 and stayed on a similar level for P3. After an optimization of the patterning processes in the R&D pilot line of AVANCIS, we achieved a new record efficiency for an all‐laser‐patterned CIS solar module: 14.7% as best value for the aperture area efficiency of a 30 × 30 cm² sized CIS module was reached. Copyright © 2014 John Wiley & Sons, Ltd.     

Zur Problematik der selektiven Erfassung von PSP-Toxinen aus Muscheln

Zusammenfassung Die Messung der PSP-Belastung (paralytic shellfish poisoning) von Schalentieren erfolgt vor allem mit Hilfe des Maus-Biotestes. Um PSP-Toxine sowohl qualitativ als auch quantitativ besser bestimmen zu können, wurden chromatographische Verfahren mit Fluorescenzdetektion entwickelt. Diese HPLC-Methoden sowie die Kopplung HPLC/MS gelangten zum Einsatz, um in spanischen Muschelkonserven ein neben Saxitoxin vermutetes zweites PSP-Toxin nachzuweisen. Es zeigte sich, daß in den 1986 in der Bundesrepublik Deutschland wegen zu hoher PSP-Konzentrationen beanstandeten Muschelkonserven vor allem Decarbamoyl-Saxitoxin enthalten war.

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The problem of the selective determination of PSP-toxins in mussels

Summary Levels of paralytic shellfish poisoning (PSP) toxins in shellfish are routinely determined by mouse bioassay: In order to improve the qualitative and quantitative determination of PSP toxins, Chromatographic techniques with fluorescence detection have been developed. These HPLC methods and the HPLC/MS coupling were used to determine a second PSP toxin which was found, in addition to saxitoxin, in canned Spanish mussels. These canned mussels were rejected in 1986 by the German food control because PSP concentrations were too high. It has been shown that these samples contained mainly dc-saxitoxin.

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Herrn Professor Dr. A. Montag zum 60. Geburtstag gewidmet