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Worldwide, Mycobacterium chimaera infections have been linked to contaminated aerosols from heater-cooler units (HCUs) during open-heart surgery. These infections have mainly been associated with the 3T HCU (LivaNova, formerly Sorin). The reasons for this and the risk of transmission from other HCUs have not been systematically assessed.
Prospective observational study.
University Hospital Basel, Switzerland.
Continuous microbiological surveillance of 3 types of HCUs in use (3T from LivaNova/Sorin and HCU30 and HCU40 from Maquet) was initiated in June 2014, coupled with an epidemiologic workup. Monthly water and air samples were taken. Construction design was analyzed, and exhausted airflow was measured.
Mycobacterium chimaera grew in 8 of 12 water samples (66%) and 22 of 24 air samples (91%) of initial 3T HCUs in use, and in 2 of 83 water samples (2%) and 0 of 41 (0%) air samples of new replacement 3T HCUs. Moreover, 7 of 12 water samples (58%) and 0 of 4 (0%) air samples from the HCU30 were positive, and 0 of 64 (0%) water samples and 0 of 50 (0%) air samples from the HCU40 were positive. We identified 4 relevant differences in HCU design compared to the 3T: air flow direction, location of cooling ventilators, continuous cooling of the water tank at 4°C, and an electronic alarm in the HCU40 reminding the user of the next disinfection cycle.
All infected patients were associated with a 3T HCU. The individual HCU design may explain the different risk of disseminating M. chimaera into the air of the operating room. These observations can help the construction of improved devices to ensure patient safety during cardiac surgery.
Astonishingly, we still do not have a history of collaboration in Poland during World War II. Klaus-Peter Friedrich shows that the building blocks for such a history already exist, however. They are scattered throughout the contemporary Polish press and studies on the Nazi occupation regime. Examples include institutionalized cooperation (Baudienst, Polish Police), ethnically defined segments of the population (Volksdeutsche), informal support of Nazi projects on ideological common ground (anti- Semitism and anticommunism), and the stance of the Polish peasantry as well as the Roman Catholic Church. Friedrich concludes that collaboration eludes study because of a mental image according to which ethnic Poles were the foremost victims of the occupiers and heroically resisted them. Questionable views of national self-interest keep Polish society from coming to terms with the past. Nevertheless, debates on “Polish collaboration” continue to recur—as they have since 1939.
Single dish spectral line surveys of high mass star-forming regions provide spectra with a very high line density, and reveal the presence of many complex molecules. Besides the prototypical Orion BN/KL region, more and more regions get surveyed and we start to get a better idea of the chemical similarities and differences. Yet, single dish studies miss an important aspect of hot cores, which is revealed by higher resolution studies with interferometers: the cores are not chemically homogeneous, but a pronounced chemical substructure exists. As an example of such an interferometric study, we will present one particular set of objects, the UC HII W3(OH) and its neighboring hot core W3(H2O) (otherwise known as the Turner-Welch object), and discuss their chemical properties.
The scalable storage of renewable energy by means of converting water to hydrogen fuels electrochemically hinges on fundamental improvements in catalytic materials. However, many applications exist where an extended lifetime is virtually crucial for their functionality and success, e.g. in case of limited accessibility such as tire pressure sensors or biomedical implants. For these kinds of applications, the ultimate power supply should be a self-renewing energy source. This strategy is pursued by the concept of Micro Energy Harvesting (MEH). Within a MEH system a micro generator converts ambient energy to electrical energy for driving an application. Unfortunately, it is not ensured that the ambient energy level will maintain always high enough to provide sufficient power to the system as harvested energy usually manifests itself in rather irregular, random and low-energy bursts. One appealing form of integrated energy storage is the use of H2/air, a so called fuel cell type (FC) battery. Such devices promise very high volumetric energy densities of more than 2000 Wh/l. Consequently, this type of battery has recently attracted more and more attention and primary as well as secondary cells have been realized. Alkaline polymer electrolyte fuel cells have been recognized as the most promising solution in order to overcome the dependency on noble metal catalysts. Nevertheless, further improvements for these kinds of fuel cells have to be reached with respect to high power. Therefore, one promising approach is to increase the skin surface of porous chromium decorated nickel electrodes for enhancement of exchange current density by forming three-dimensional (3D) microstructures directly into the electrode. Therefore, a novel laser structuring process was applied using ultrashort laser pulses. Ultrashort laser processing of complex multimaterial systems for energy storage allow for precise material removal without changing the material properties. By applying this novel laser-based structuring technique, 3D microstructures could be formed permitting shortened diffusion lengths between the electrolyte and the electrode surface being necessary for increased exchange current densities.
In the literature various types of restarting automata have been studied that are based
on contextual rewriting. A word w is accepted by such an automaton if,
starting from the initial configuration that corresponds to input w, the
word w is reduced to the empty word by a finite number of applications of
these contextual rewritings. This approach is reminiscent of the notion of McNaughton
families of languages. Here we put the aforementioned types of restarting automata into
the context of McNaughton families of languages, relating the classes of languages
accepted by these automata in particular to the class GCSL of growing context-sensitive
languages and to the class CRL of Church–Rosser languages.
Highly efficient polytype 4H silicon carbide (4H-SiC) p–n diodes for ultraviolet (UV) light detection have been fabricated, characterized, and exposed to high-intensity mercury lamp irradiation (up to 17 mW/cm2). The behavior of the photocurrent response under UV light irradiation using a low-pressure mercury UV-C lamp (4 mW/cm²) and a medium-pressure mercury discharge lamp (17 mW/cm²) has been studied. We report on long-term UV photoaging tests performed for up to 22 mo. Results demonstrate the robustness of SiC photodiodes against UV radiation. The devices under test showed an initial burn-in effect, i.e., the photocurrent response dropped by less than 5% within the first 40 h of artificial UV aging. Such burn-in effect under UV stress was also observed for previously available polytype 6H silicon carbide (6H–SiC) p–n photodetectors. After burn-in, no measurable degradation has been detected, which makes the devices excellent candidates for high irradiance UV detector applications.
Charge controlled power switching devices fabricated in 4H-Silicon Carbide are discussed in this paper. After comparing possible structures, results on prototype devices are presented. The presentation will give an overview about the developments of SiC power switches at SiCED, in addition some potential applications serving as an accelerator for the SiC power switch development will be sketched. The performance of vertical JFETs will be analyzed in detail. These can be operated as a single device as well as in combination with a low voltage silicon power MOSFET. The result of the hybrid assembly is a normally off device which behaves for the user more and more like a classical MOSFET with respect to the input as well as the output characteristic. Several improvements where performed which make the device more attractive for the customer. It will be shown which factors drive these optimization and how they can be implemented. Although the primary target for this device is the >1000V blocking voltage range, it will be discussed how the huge 600V power switch market can be made accessible for SiC power devices too. Intensively the high temperature performance of SiC JFETs and Si/SiC cascodes is discussed. Additionally, other developments like silicon power MOSFETs or high voltage switches will be mentioned.
In this paper, we present results of epitaxial layer deposition for production needs using our hot-wall CVD multi-wafer system VP2000HW from Epigress with a capability of processing 6×100mm wafers per run. Intra-wafer and wafer-to-wafer homogeneities of doping and thickness for full-loaded 6×100mm runs will be shown and compared to results of the former 7×3″ setup. The characteristic of the run-to-run reproducibility for the 6×100mm setup will be discussed. To demonstrate the suitability of the reactor for device production results on Schottky Barrier Diodes (SBD) processed in the multi-wafer system will be given. Furthermore, we show results for n- and p-type SiC homoepitaxial growth on 3″, 4° off-oriented substrates using a single-wafer hot-wall reactor VP508GFR from Epigress for the development of PiN-diodes with blocking voltages above 6.5 kV. Characteristics of n- and p-type epilayers and doping memory effects are discussed. 6.5 kV PiN-diodes were fabricated and electrically characterized. Results on reverse blocking behaviour, forward characteristics and drift stability will be presented.
In this paper we present results of epitaxial layer deposition for production needs using our hot-wall CVD multi-wafer system. This equipment exhibits a capacity of 7x3” wafers per run and can be upgraded to a 6x4” setup. Characteristics of epilayers and reproducibility of the proc-esses are reported. Furthermore, we show recent results of p-type SiC homoepitaxial growth on 3” 4° off-oriented substrates using a single-wafer hot-wall CVD. The dependence of layer prop-erties on growth parameters, doping and thickness uniformity as well as doping memory effects are discussed. For the characterization of epitaxially grown pn-junctions first research grade pin-diodes were fabricated. The p-type emitters were either deposited in the same growth run to-gether with the n-type buffer and drift layers (continuous growth) or the n- and p-layers were grown in two different growth runs (separate growth).
The oxygen vacancy ordering process and displacive transitions have been characterised in the system CaTiO3-CaFeO2.5 as a function of composition and temperature at atmospheric pressure using X-ray diffraction, Mössbauer spectroscopy, infrared spectroscopy, transmission electron microscopy, electron energy loss spectroscopy, neutron diffraction and electrical conductivity methods. With increasing concentration of vacancies the following sequence is observed: isolated defects → short defect chains → infinite chains in layers. Similar experiments at high pressures and temperatures have been conducted to determine the nature of oxygen vacancies in the lower mantle phases (Mg,Fe)(Si,Al)O3-σ and Ca(Si,Fe)O3-σ perovskite.
In this work, different set-ups as well as different transducer materials have been investigated in order to develop a hydrogen peroxide (H2O2) sensor for the gas phase. The sensor is based on a combined physical/chemical transduction mechanism and should be able to detect high H2O2 concentrations up to 10 Vol.%. Different sensor arrangements are presented that are based on a “three sensor” cell and a diffusion cell. As transducer materials manganese oxide and copper alloys have been investigated. For the reference part of the sensor set-up, Teflon and enamel have been tested as passivating material.
The degradation behavior of biodegradable multiblock copolymers (PDC) containing poly(p-dioxanone) hard segments (PPDO) and crystallizable poly(epsilon-caprolactone) switching segments (PCL) synthesized via co-condensation of two oligomeric macrodiols with an aliphatic diisocyanate as junction unit was explored in in vivo and in vitro experiments. The in vitro experiments for enzymatic degradation resulted that the poly(epsilon-caprolactone) segments are degraded faster, than the poly(p-dioxanone) segments. During degradation the outer layer of the test specimen becomes porous. Finally non-soluble degradation products in form of particles were found at the surface. This observation is in good agreement with the in vivo studies, where the non-soluble degradation products in the periimplantary tissues showed a diameter of 1 – 3 micron.
The Supernova Working Group was re-established at the IAU XXV General Assembly in Sydney, 21 July 2003, sponsored by Commissions 28 (Galaxies) and 47 (Cosmology). Here we report on some of its activities since 2005.