Experimental Investigation of the Spread of Airborne CFU in a Research-OR under Different Air Flow Regimes using Tracer Particles

Aim of this experimental study is to compare different types of ventilation in operating rooms (OR) regarding the highest possible patient protection against airborne germs based on particle counting. Tracer particles with the size of the airborne colony-forming units (CFU) occurring in OR shall be generated to derive representative statements about the removal of germs. In addition, they origin from aerosol generators mounted on heated person simulators to obtain a realistic dispersion of the contamination. It can be shown that the aerosol generators designed produce particles in the relevant size classes of the airborne germs emitted by OR personnel.publishedVersio

High-Performance Solid Medium Thermal Energy Storage System for Heat Supply in Battery Electric Vehicles: Proof of Concept and Experimental Testing

The reduction of global CO2 emissions requires cross-sectoral measures to reduce fossil energy consumptions and to strengthen the expansion of renewable energy sources. One element for this purpose are thermal energy storage systems. They enable, due to their time-decoupled operation, increases in systemic efficiency and flexibility in various industrial and power plant processes. In the electricity and heat sector such solutions are already commercially available for large-scale applications or are focused in diverse R&D projects, but are largely new in the transport sector. By transferring existing concepts specifically to the requirements for the heat supply of battery electric vehicles, efficiency improvements can also be achieved in the transport sector. The idea is to provide the required heat for the interior during cold seasons via a previously electrical heated thermal energy storage system. Thus, battery capacities can be saved, and the effective range of the vehicle can be increased. Basic prerequisites for this concept are high systemic storage densities and high performances, which must be justified to commercial battery powered PTC-elements. Compared to large-scale applications, this results in new challenges and design solutions needing finally a proof of concept and experimental tests under vehicle typical specifications. For the first time, a novel thermal energy storage system based on ceramic honeycombs with integrated heating wires and a double-walled, thermally insulated storage containment was developed and constructively realized. This storage system meets all the requirements for the heat supply, reaches high systemic storage and power densities and allows due to its high flexibility a bifunctional operation use: a cyclic storage and a conventional heating mode. In the focused storage operation, high-temperature heat is generated electrically through heating wires during the charging period and transferred efficiently via thermal radiation to the ceramic honeycombs. During the discharging period (driving) the stored thermal energy is used for heating the interior by a bypass control system at defined temperatures with high thermal output. The systematic measurement campaigns and successful model validations confirm high electrical heating powers of 6.8 kW during the charging period and a heat supply with a thermal output of 5 kW over more than 30 min during the discharging period. Despite current infrastructure and test rig restrictions, high systemic storage densities of 155 Wh/kg with constant discharging outlet temperatures are reached. Compared to battery powered heating systems, the experimental results for the developed thermal energy storage system confirm an excellent level of competitiveness due to its high performance, operational flexibility and low-cost materials

Ice nucleation efficiency of natural dust samples in the immersion mode

A total of 12 natural surface dust samples, which were surface-collected on four continents, most of them in dust source regions, were investigated with respect to their ice nucleation activity. Dust collection sites were distributed across Africa, South America, the Middle East, and Antarctica. Mineralogical composition has been determined by means of X-ray diffraction. All samples proved to be mixtures of minerals, with major contributions from quartz, calcite, clay minerals, K-feldspars, and (Na, Ca)-feldspars. Reference samples of these minerals were investigated with the same methods as the natural dust samples. Furthermore, Arizona test dust (ATD) was re-evaluated as a benchmark. Immersion freezing of emulsion and bulk samples was investigated by differential scanning calorimetry. For emulsion measurements, water droplets with a size distribution peaking at about 2 µm, containing different amounts of dust between 0.5 and 50 wt % were cooled until all droplets were frozen. These measurements characterize the average freezing behaviour of particles, as they are sensitive to the average active sites present in a dust sample. In addition, bulk measurements were conducted with one single 2 mg droplet consisting of a 5 wt % aqueous suspension of the dusts/minerals. These measurements allow the investigation of the best ice-nucleating particles/sites available in a dust sample. All natural dusts, except for the Antarctica and ATD samples, froze in a remarkably narrow temperature range with the heterogeneously frozen fraction reaching 10 % between 244 and 250 K, 25 % between 242 and 246 K, and 50 % between 239 and 244 K. Bulk freezing occurred between 255 and 265 K. In contrast to the natural dusts, the reference minerals revealed ice nucleation temperatures with 2–3 times larger scatter. Calcite, dolomite, dolostone, and muscovite can be considered ice nucleation inactive. For microcline samples, a 50 % heterogeneously frozen fraction occurred above 245 K for all tested suspension concentrations, and a microcline mineral showed bulk freezing temperatures even above 270 K. This makes microcline (KAlSi3O8) an exceptionally good ice-nucleating mineral, superior to all other analysed K-feldspars, (Na, Ca)-feldspars, and the clay minerals. In summary, the mineralogical composition can explain the observed freezing behaviour of 5 of the investigated 12 natural dust samples, and partly for 6 samples, leaving the freezing efficiency of only 1 sample not easily explained in terms of its mineral reference components. While this suggests that mineralogical composition is a major determinant of ice-nucleating ability, in practice, most natural samples consist of a mixture of minerals, and this mixture seems to lead to remarkably similar ice nucleation abilities, regardless of their exact composition, so that global models, in a first approximation, may represent mineral dust as a single species with respect to ice nucleation activity. However, more sophisticated representations of ice nucleation by mineral dusts should rely on the mineralogical composition based on a source scheme of dust emissions

Active Reconfigurable Intelligent Surface for the Millimeter-Wave Frequency Band: Design and Measurement Results

Reconfigurable intelligent surfaces (RISs) will play a key role to establish reliable low-latency millimeter wave (mmWave) communication links for indoor automation and control applications. In case of a blocked line-of-sight between the base station (BS) and the user equipment (UE), a RIS mounted on a wall or on a ceiling enables a bypass for the radio communication link. In this work, we present an active RIS for the mmWave frequency band. Each RIS element uses a field effect transistor (FET) to amplify the reflected signal and an orthogonal polarization transformation to increase the isolation between impinging and reflected radio wave. By switching the bias voltage at gate and drain of the FET we can establish four states for each RIS element: two reflection states with different phase shifts, an active amplification and an off state. We present results of the active RIS with 37 patch antenna elements arranged in a hexagonal grid for a center frequency of 25.8 GHz. The RIS field patterns obtained by numerical simulations and by empirical measurements in an anechoic chamber are compared. They show a good match and the received power is improved by 12 dB in the active mode of the RIS compared to the reflective mode.Comment: Submitted to IEEE Wireless Communications and Networking Conference, Dubai, United Arab Emirates, April 202

Bleeding skin lesions in gestating sows of a piglet producing farm in Austria.

BACKGROUND Stomoxys calcitrans, the stable fly, occurs in pig producing countries worldwide. While in cattle the impact of this blood sucking insect is quite well described, its role in pig production is poorly investigated. Here we describe a case of a massive stable fly overpopulation in the gestation unit of a piglet producing farm in Austria that resulted in bleeding skin lesions in bitten sows. CASE PRESENTATION In October 2021, the responsible herd veterinarian of the case farm reported of sows in the gestation area presenting with bloody crusts on the whole skin surface of the body and of bleeding skin lesions. 33/55 sows were affected by moderate to severe skin lesions. Reproductive performance decreased during the time of massive stable fly overpopulation. Sows in the gestation unit showed defensive behaviour and at a certain time point resigned and accepted being bitten by stable flies. After controlling the fly population, reproductive performance improved and even exceeded the performance before the massive overgrowth of the stable fly population. CONCLUSIONS Stable flies are a serious harm to pigs and should be kept in mind for improved animal health and welfare. Knowledge about the determination of Stomoxys calcitrans and early recognition of an increasing stable fly population in pig farming systems followed by proper insect control measures have to be performed to reduce losses caused by this harming insect

Monitoring activated clotting time for combined heparin and aprotinin application: in vivo evaluation of a new aprotinin-insensitive test using Sonoclot

Objective: Kaolin-based activated clotting time assessed by HEMOCHRON (HkACT) is a clinical standard for heparin monitoring alone and combined with aprotinin during cardiopulmonary bypass (CPB). However, aprotinin is known to prolong not only celite-based but also kaolin-based activated clotting time. Overestimation of activated clotting times implies a potential hazardous risk of subtherapeutic heparin anticoagulation. Recently, a novel ‘aprotinin-insensitive' activated clotting time test has been developed for the SONOCLOT analyzer (SaiACT). The aim of our study was to evaluate SaiACT in patients undergoing CPB in presence of heparin and aprotinin. Methods: Blood samples were taken from 44 elective cardiac surgery patients at the following measurement time points: baseline (T0); before CPB after heparinization (T1 and T2); on CPB, before administration of aprotinin (T3); 15, 30, and 60min on CPB after administration of aprotinin (T4, T5, and T6); after protamine infusion (T7). On each measurement time point, activated clotting time was assessed with HkACT and SaiACT, both in duplicate. Furthermore, the rate of factor Xa inhibition and antithrombin concentration were measured. Statistical analysis was done using Bland and Altman analysis, Pearson's correlation, and ANOVA with post hoc Bonferroni-Dunn correction. Results: Monitoring anticoagulation with SaiACT showed reliable readings. Compared to the established HkACT, SaiACT values were lower at all measurement time points. On CPB but before administration of aprotinin (T3), SaiACT values (mean±SD) were 44±118s lower compared to HkACT. However, the difference between the two measurement techniques increased significantly on CPB after aprotinin administration (T4-T6; 89±152s, P=0.032). Correlation of ACT measurements with anti-Xa activity was unchanged for SaiACT before and after aprotinin administration (r2=0.473 and 0.487, respectively; P=0.794), but was lower for HkACT after aprotinin administration (r2=0.481 and 0.361, respectively; P=0.041). On CPB after administration of aprotinin, 96% of all ACT values were classified as therapeutic by HkACT, but only 86% of all values were classified therapeutic if ACT was determined by SaiACT. Test variability was comparable for SaiACT and HkACT. Conclusions: The use of SaiACT may result in more consistent heparin management that is less affected by aprotinin and a corresponding increase in heparin administration for patients receiving aprotini

Natural Hazards under Climate Change Conditions: A Case Study of Expectations and their Normative Significance in Protecting Alpine Communities

Climate change increases the frequency and intensity of certain kinds of natural hazard events in alpine areas. This interdisciplinary study addresses the hypothetical possibility of relocating the residents of three alpine areas in Austria: the Sölk valleys, the Johnsbach valley, and the St. Lorenzen/Schwarzenbach valleys. Our particular focus is on these residents’ expectations about such relocations. We find that (1) many residents expect that in the next decades the state will provide them with a level of natural hazards protection, aid, and relief that allows them to continue to live in these valleys; (2) this expectation receives some legal protection but only when it is associated with fundamental rights; and (3) the expectation is morally significant, i.e., it ought to be considered in assessing the moral rightness or justness of relocation policies. These results suggest legal changes and likely extend to many other (Austrian) alpine areas as well

Characterization of the gaseous spacecraft environment of Rosetta by ROSINA

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90700/1/AIAA-2011-3822-983.pd