Introduction: The kinetics of protein oxidation, monitored in breath, and its contribution to the whole body protein status is not well established. Objectives: To analyze protein oxidation in various metabolic conditions we developed/validated a 13C-protein oxidation breath test using low enriched milk proteins. Method/Design: 30 g of naturally labeled 13C-milk proteins were consumed by young healthy volunteers. Breath samples were taken every 10 min and 13CO2 was measured by Isotope Ratio Mass Spectrometry. To calculate the amount of oxidized substrate we used: substrate dose, molecular weight and 13C enrichment of the substrate, number of carbon atoms in a substrate molecule, and estimated CO2-production of the subject based on body surface area. Results: We demonstrated that in 255 min 20% ± 3% (mean ± SD) of the milk protein was oxidized compared to 18% ± 1% of 30 g glucose. Postprandial kinetics of oxidation of whey (rapidly digestible protein) and casein (slowly digestible protein) derived from our breath test were comparable to literature data regarding the kinetics of appearance of amino acids in blood. Oxidation of milk proteins was faster than that of milk lipids (peak oxidation 120 and 290 minutes, respectively). After a 3-day protein restricted diet (~10 g of protein/day) a decrease of 31% ± 18% in milk protein oxidation was observed compared to a normal diet. Conclusions: Protein oxidation, which can be easily monitored in breath, is a significant factor in protein metabolism. With our technique we are able to characterize changes in overall protein oxidation under various meta-bolic conditions such as a protein restricted diet, which could be relevant for defining optimal protein intake under various conditions. Measuring protein oxidation in new-born might be relevant to establish its contribution to the protein status and its age-dependent development.
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Urban water bodies like ponds or canals are commonly assumed to provide effective cooling in hot periods. Some of the evidence that feeds this assertion is based on remote sensing observations at relatively large scales. Such observations generally reveal reduced surface temperatures of water bodies during daytime, relative to their urbanized environment. This is to be expected because of the extremely large heat capacity of water in combination with its ability to transport heat away from the water surface by turbulent mixing. However, this also implies that the cooling of a water body may proceed only slowly, which may result in higher night-time surface temperatures. This can lead to water bodies contributing to night-time urban heat islands. The existence of a surface-air temperature gradient is a necessary, but insufficient condition for water bodies to influence their environment. In order to noticeably affect the atmospheric temperature, the cooler or warmer air near the water surface needs to be transported to the urban surroundings. Furthermore, for humans such effects are generally only relevant if they are present at a height of 1-2 m. This requires the fetch over the water to be sufficiently large, so that the internal boundary layer can grow to these atmospheric levels. Furthermore, since not only temperature but also wind (ventilation), humidity and radiation contribute to the heat load of humans, possible cooling or heating effects need to be considered in terms of physiologically meaningful quantities, such as the Physiological Equivalent Temperature (PET). Taking such considerations into account, it is no surprise that the effect of water bodies on their atmospheric surroundings are generally found to be small or even nearly absent when considering evidence from atmospheric measurements.Although there are indications that proper combinations of shading, evaporation and ventilation interventions around water bodies can help to keep their surroundings cooler during summer, it is virtually unknown how these strategies can be optimally combined in designs to counter urban heat effectively. The ‘Really cooling water bodies in cities’ (REALCOOL) project explores possible cooling effects of such combinations for relatively small urban water bodies (characteristic horizontal dimension up to a few tens of meters, maximum depth 3m). The goal is to create evidence-based design guidelines of cooling urban water environments — design prototypes — meant for application in urban and landscape design practice.This presentation will address the cooling effects of the design prototypes evaluated with micrometeorological simulations. Special attention will be paid to the cooling effects of the water bodies in the designs. These were assessed using ENVI_MET version 4.1.3., which allows the user to choose the intensity of turbulent mixing of the water. Comparisons with observations and results from water temperature simulations with a model that assumes perfectly mixed water (the “Cool Water Tool”, CWT) showed that enhancing the turbulent mixing in ENVI_MET strongly improves water temperature simulations. Three design experiments were implemented in ENVI_MET: Exp1) testbeds, which are spatial reference situations derived from an inventory of common urban water bodies in The Netherlands, characterized by the shape and dimensions of the water body and the type of urban environment; Exp2) testbeds in which the area occupied by the water was replaced with the paving materials or vegetation flanking the water body in the original testbed; Exp3) design options with optimal combinations of shading, evaporation and ventilation. All simulations were performed for the same set of meteorological conditions, representing a typical heatwave day in The Netherlands. The initial water temperature depends on the water depth and was determined from simulations with the CWT, run for the same heatwave day repetitively until a quasi-equilibrium state was reached.Model outcomes from ENVI_MET were evaluated for the normally warmest period during daytime (around 15:00 CET) and the coolest period during night-time (around 5:00 CET) in the summer, using water temperature just below the water surface and using air temperature and PET at a height of 1.5m. The cooling effect is defined as the difference in air temperature and PET, respectively, between the different design experiments. The differences were computed from the spatial averages over two areas: the area directly above the water surface (Exp1, Exp3) or its replacement (Exp2) and the area directly bordering the water (like quays and sidewalks, called “pedestrian area” hereafter).The simulations with ENVI_MET suggest that the cooling effect of small water bodies on the air temperature is quite small and often negligible (Exp1-Exp2). This is also true for the optimized designs (Exp3-Exp2). The presence of the water body in the testbeds reduced the daytime air temperature in the afternoon by at most 0.8°C directly over the water body and 0.6°C in the pedestrian area (Exp1-Exp2). PET was reduced by at most 1.8°C and 1.9°C, respectively. During night-time, there was a very slight warming effect in a majority of cases, of at most 0.3°C in air temperature. Warming effects in terms of PET were even smaller. The optimized designs led to a reduction of water temperature of at best 0.5°C, relative to the reference situations (Exp1-Exp3). Air temperature was reduced by at most 0.8°C, relative to the temperature in original testbeds. The Physiological Equivalent Temperature (PET) could be reduced by as much as 7°C at 15:00 CET, but this difference was mainly due to shading effects of trees, not to the presence of water.We conclude that small urban water bodies like the ones tested here may not be the most relevant adaptation measure to create cooler urban environments. Their size may simply be too small to have meaningful thermal effects in their surroundings, in accordance with micrometeorological theory on the development of internal boundary layers. Only for water bodies that are sufficiently large cooling effects may become noticeable. This is then also true for possible warming effects. However, the openness of urban water bodies and their surroundings allows ventilation and provides room for trees that provide shade. The combination of these aspects which both lead to cooling effects was found to dominate favourable changes in daytime PET in particular.
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A local operating theater ventilation device to specifically ventilate the wound area has been developed and investigated. The ventilation device is combined with a blanket which lies over the patient during the operation. Two configurations were studied: Configuration 1 where HEPA-filtered air was supplied around and parallel to the wound area and Configuration 2 where HEPA-filtered air was supplied from the top surface of the blanket, perpendicular to the wound area. A similar approach is investigated in parallel for an instrument table. The objective of the study was to verify the effectiveness of the local device. Prototype solutions developed were studied experimentally (laboratory) and numerically (CFD) in a simplified setup, followed by experimental assessment in a full scale mock-up. Isothermal as well as non-isothermal conditions were analyzed. Particle concentrations obtained in proposed solutions were compared to the concentration without local ventilation. The analysis procedure followed current national guidelines for the assessment of operating theater ventilation systems, which focus on small particles (<10 mm). The results show that the local system can provide better air quality conditions near the wound area compared to a theoretical mixing situation (proof-of-principle). It cannot yet replace the standard unidirectional downflow systems as found for ultraclean operating theater conditions. It does, however, show potential for application in temporary and emergency operating theaters
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