Titel Deelnemers "Korte inhoud" "Maintenance fluid therapy and fluid creep impose more significant fluid, sodium, and chloride burdens than resuscitation fluids in critically ill patients" "Niels Van Regenmortel, Walter Verbrugghe, Ella Roelant, Tim Van den Wyngaert, Philippe Jorens" "Purpose: Research on intravenous fluid therapy and its side effects, volume, sodium, and chloride overload, has focused almost exclusively on the resuscitation setting. We aimed to quantify all fluid sources in the ICU and assess fluid creep, the hidden and unintentional volume administered as a vehicle for medication or electrolytes. Methods: We precisely recorded the volume, sodium, and chloride burdens imposed by every fluid source administered to 14,654 patients during the cumulative 103,098 days they resided in our 45-bed tertiary ICU and simulated the impact of important strategic fluid choices on patients' chloride burdens. In septic patients, we assessed the impact of the different fluid sources on cumulative fluid balance, an established marker of morbidity. Results: Maintenance and replacement fluids accounted for 24.7% of the mean daily total fluid volume, thereby far exceeding resuscitation fluids (6.5%) and were the most important sources of sodium and chloride. Fluid creep represented a striking 32.6% of the mean daily total fluid volume [median 645 mL (IQR 308-1039 mL)]. Chloride levels can be more effectively reduced by adopting a hypotonic maintenance strategy [a daily difference in chloride burden of 30.8 mmol (95% CI 30.5-31.1)] than a balanced resuscitation strategy [daily difference 3.0 mmol (95% CI 2.9-3.1)]. In septic patients, non-resuscitation fluids had a larger absolute impact on cumulative fluid balance than did resuscitation fluids. Conclusions: Inadvertent daily volume, sodium, and chloride loading should be avoided when prescribing maintenance fluids in view of the vast amounts of fluid creep. This is especially important when adopting an isotonic maintenance strategy." "Geochemistry of highly saline fluids in siliciclastic sequences: genetic implications for post-Variscan fluid flow in the Moravosilesian Palaeozoic of the Czech Republic" "Philippe Muchez" "Ubiquitous post-Variscan dolomites occur in Zn–Pb–Cu veins at the Nízký Jeseník Mountains and the Upper Silesian Basin (Lower and Upper Carboniferous siliciclastics at the eastern part of the Bohemian Massif). Crush–leach, stable isotope (oxygen and carbon) and microthermometry analysis of the fluid inclusions in dolomites enable understanding the geochemistry, origin and possible migration pathways of the fluids. Homogenisation temperatures of fluid inclusions range between 66 and 148°C, with generally higher temperatures in the Nízký Jeseník Mountains area than in the Upper Silesian Basin. The highest homogenisation temperatures (up to 148°C) have been found near major regional faults and the lowest in a distant position or at higher stratigraphic levels. Highly saline (16.6–28.4 eq. wt% NaCl) H2O–NaCl–CaCl2 ± MgCl2 fluids occur in inclusions. Na–Cl–Br systematics of trapped fluids and a calculated oxygen isotopic fluid composition between −0.9 and +3.0‰ V-SMOW indicate that the fluid was derived from evaporated seawater. Stable isotopic modelling has been used to explain stable isotopic trends. Isotopic values (δ13C = −6.0/+2.0‰ V-PDB, δ18O = +15.5/+22.5‰ V-SMOW of dolomites) resulted from fractionation and crystallisation within an open system at temperatures between 80 and 160°C. Rock-buffering explains the isotopic composition at low w/r ratios. Organic matter maturation caused the presence of isotopically light carbon in the fluids and fluid–rock interactions largely controlled the fluid chemistry (K, Li, Br and Na contents, K/Cl, I/Cl and Li/Cl molar ratios). The fluid chemistry reflects well the interaction between the fluid and underlying limestones as well as with clay- and organic-rich siliciclastics. No regional trends in temperature or fluid geochemistry favour a fluid migration model characterised by an important vertical upward migration along major faults. A permeable basement and fractured sedimentary sequence enhanced the general nature of the fluid system. Fluid characteristics are comparable with the main post-Variscan fluid flow systems in the Polish (Cracow-Silesian ore district) and German sedimentary basins." "The Nature of Mineralizing Fluids of the Kipushi Zn-Cu Deposit, Katanga, Democratic Repubic of Congo: Quantitative Fluid Inclusion Analysis using Laser Ablation ICP-MS and Bulk Crush-Leach Methods" "Philippe Muchez" "Fluid inclusions from the epigenetic Zn-Cu deposit of Kipushi, central African copper belt, Katanga, Democratic Republic of Congo, have been subjected to an integrated microthermometric, bulk crush-leach and laser ablation inductively coupled plasma mass spectrometric (LA-ICP-MS) study to elucidate the physicochemical conditions of ore formation and the origin of the mineralizing fluids. The Kipushi deposit is hosted in carbonates and partly in siliciclastic rocks that have undergone regional, low-grade greenschist facies metamorphism and which were strongly deformed during the Lufilian orogeny (main deformation phase ~550 Ma). Investigation of host-rock, gangue, and ore samples enabled reconstruction of the paragenesis of ore deposition. The main Zn-Cu (+Ge, Pb) sulfide mineralization was accompanied by three generations of hydrothermal dolomite and a generation of coarse-grained quartz. Primary and pseudosecondary fluid inclusions in these minerals contain predominantly halite-saturated, aqueous brines (~30–43 wt % NaCl equiv), with locally unidentified trapped solids. These inclusions mostly decrepitate upon heating before total homogenization, which could suggest that they also trapped excess carbonic vapor. They show petrographic and microthermometric evidence for postentrapment reequilibration, prohibiting their use as accurate geothermometers and geobarometers. Previous studies on chlorite and sphalerite geothermometry framed the formation temperature of the Kipushi Cu-Zn deposit between ~290° to 380°C. Younger fluids are present as secondary inclusions in the gangue minerals and as primary fluid inclusions in sphalerite from a minor secondary mineralization phase. These two-phase aqueous inclusions have a slightly lower salinity (~23–31 wt % NaCl equiv) and have homogenization temperatures ranging from ~170° to" "Dielectric constant of fluids and fluid mixtures at criticality" "Patricia Losada-Pérez, Germán Pérez-Sánchez, Claudio A Cerdeirina, Jan Thoen" "The behavior of the dielectric constant epsilon of pure fluids and binary mixtures near liquid-gas and liquid-liquid critical points is studied within the concept of complete scaling of asymmetric fluid-fluid criticality. While mixing of the electric field into the scaling fields plays a role, pressure mixing is crucial as the asymptotic behavior of the coexistence-curve diameter in the epsilon-T plane is concerned. Specifically, it is found that the diameters, characterized by a vertical bar T-T-c vertical bar(1-alpha) singularity in the previous scaling formulation [J.V. Sengers, D. Bedeaux, P. Mazur, and S. C. Greer, Physica A 104, 573 (1980)], gain a more dominant vertical bar T-T-c vertical bar(2 beta) term, whose existence is shown to be supported by literature experimental data. The widely known vertical bar T-T-c vertical bar(1-alpha) singularity of epsilon along the critical isopleth in the one-phase region is found to provide information on the effect of electric fields on the liquid-liquid critical temperature: from experimental data it is inferred that T-c usually decreases as the magnitude of the electric field is enhanced. Furthermore, the behavior of mixtures along an isothermal path of approach to criticality is also analyzed: theory explains why the observed anomalies are remarkably higher than those associated to the usual isobaric path." "Dielectric constant of fluids and fluid mixtures at criticality" "Jan Thoen" "The behavior of the dielectric constant epsilon of pure fluids and binary mixtures near liquid-gas and liquid-liquid critical points is studied within the concept of complete scaling of asymmetric fluid-fluid criticality. While mixing of the electric field into the scaling fields plays a role, pressure mixing is crucial as the asymptotic behavior of the coexistence-curve diameter in the epsilon-T plane is concerned. Specifically, it is found that the diameters, characterized by a vertical bar T-T-c vertical bar(1-alpha) singularity in the previous scaling formulation [J.V. Sengers, D. Bedeaux, P. Mazur, and S. C. Greer, Physica A 104, 573 (1980)], gain a more dominant vertical bar T-T-c vertical bar(2 beta) term, whose existence is shown to be supported by literature experimental data. The widely known vertical bar T-T-c vertical bar(1-alpha) singularity of epsilon along the critical isopleth in the one-phase region is found to provide information on the effect of electric fields on the liquid-liquid critical temperature: from experimental data it is inferred that T-c usually decreases as the magnitude of the electric field is enhanced. Furthermore, the behavior of mixtures along an isothermal path of approach to criticality is also analyzed: theory explains why the observed anomalies are remarkably higher than those associated to the usual isobaric path." "The 4-indications of Fluid Therapy: Resuscitation, Replacement, Maintenance and Nutrition Fluids, and Beyond" "Manu L.N.G. Malbrain, Michaël Maurits M Mekeirele, Matthias Raes, Steven Hendrickx, Idris Ghijselings, Luca Malbrain, Adrian Wong" "Multiphase fluid hammer with non- cryogenic and cryogenic fluids" "Maria Rosaria Vetrano, Johan Steelant" "Disregarded effect of biological fluids in siRNA delivery : human ascites fluid severely restricts cellular uptake of nanoparticles" "George Dakwar, Kevin Braeckmans, Wim Ceelen, Katrien Remaut" "VALIDATION AND IMPLEMENTATION OF THE SYSMEX XN 2000 BODY FLUID MODULE FOR WHITE BLOOD CELL DIFFERENTIAL COUNT IN SEROUS FLUIDS" "Delphine Labaere, Nancy Boeckx, Inge Geerts, Marc Moens, Marleen Van den Driessche" "Advanced Computational Fluid Dynamics modelling for a more sustainable and energy efficient postharvest cold chain of pome fruit" "Willem Gruyters" "The demand for fresh fruit is high and expected to increase significantly in the near future due to consumers targeting a healthy diet. This inherently leads to the need for high-quality fruit being available year-round for fresh consumption. However, freshly harvested fruit solely rely on their internal reserves to maintain their respiration metabolism. By lowering fruit temperature, the respiration rate can be reduced, thus retarding the onset of fruit senescence and extending their storage life. The latter is usually in combination with controlled atmosphere conditions or other postharvest treatments. In order to be flexible in reply to market demands while ensuring year-round availability of high quality produce to the consumers, improving current cooling and storage strategies is necessary. However, possibilities for experimental tests are limited due to costs and fruit availability, while the number of design variables within the cold chain is high. A cost-effective alternative to experiments is numerical modelling with computational fluid dynamics (CFD). The main objective of this PhD research was to develop, apply and analyse CFD models to simulate and improve cooling processes of pome fruit in different steps of the postharvest cold chain. In particular, the aim was to improve predictions of transient and spatially resolved cooling processes at different spatial scales; from individual fruit to large industrial cool rooms. To reach this goal, various advanced and novel numerical approaches were explored to model the fruit stacks and when possible, validated with experiments. Ultimately, these models were employed to evaluate practical postharvest cooling applications. During long-term storage of apples, the main costs are associated with the energy consumption of the cooling process. In the first research chapter, a CFD model was developed to allow quantitative evaluation of energy saving measures during long-term storage of apples in industrial cool rooms, while considering effects on fruit quality. The porous medium approach was adopted to simulate cold storage of large fruit bins stacked in industrial cool rooms. A transient CFD model was used to evaluate three cooling scenarios with a different temperature differential around the optimal apple storage temperature. The dynamic coolstore behaviour was captured by extending the CFD model with an evaporator and controller model. In addition, this model was coupled with a kinetic model of apple firmness to predict the time and spatial evolution of apple quality in the coolstore during long-term storage. Implementing a small temperature differential was shown to result in a better overall performance in terms of uniformity, final product quality and energy consumption. The cooling rate and uniformity, and energy consumption of forced air precooling greatly depend on the aerodynamic design and configuration of the fruit packages. In the second research chapter, a CFD model was developed and applied to compare apple fruit cooling performance of a conventional corrugated fibreboard cardboard (CFC) box to that of an alternative reusable plastic crate (RPC). Since the porous medium approach previously used is only applicable in configurations where the crate to fruit dimension is sufficiently large, an explicit modelling approach was used instead. In this model, fruit were approximated as regular spheres with a fixed diameter. Computations were verified with experiments and captured trade-offs between cooling rates and energy consumption. A mismatch between the position of vent holes and fruit-supporting trays created isolated regions for airflow, resulting in large temperature heterogeneities in the standard CFC box. Although both cooling uniformity and energy use were found to be the best for RPCs, high airflow rates at low temperatures might cause chilling injury to the apples. Fruit shape and size show considerable variability, and thus affect the cooling process significantly. In the third research chapter, a new explicit CFD modelling approach that considers random stacking and variable fruit shapes was developed and evaluated against simpler approaches. Variable 3D apple and pear models were created by means of a validated geometric model generator based on X-ray computed tomography images of individual fruit. The fruit were randomly stacked into a geometrical model of a CFC box using a Discrete Element Method. A horizontal forced-air cooling process was simulated for three such apple filling patterns using CFD and results were compared to those obtained with fruit represented by equivalent spheres. No significant difference in average aerodynamic resistance between the real apple shape and its spherical representation was found. However, the degree of cooling uniformity between individual fruit was overestimated: cooling uniformity decreased when realistic fruit shapes were used. This difference between real and simplified product shapes was even larger for a box filled with pear fruit that are more different from a spherical shape. Validation of explicit CFD models requires one-to-one comparison of predicted and measured temperature profiles in specific fruit stacks. In the final research chapter, CFD models were developed from X-ray computed tomography scans of boxes filled with pear fruit. This allowed direct validation against experimental measurements in the same stacking geometry and assessing cooling performance differences caused by variable fruit shapes. The actual filling patterns of different pear cultivars, with significant shape differences, in a standard cardboard package were reconstructed and implemented in an explicit CFD model of a horizontal forced-air cooling process. The simulated cooling profiles were successfully compared with experiments with only a maximum difference of 9 % in cooling time. The contribution of the filling pattern to the overall pressure drop over the box was quantified to be only 3 %, and intercultivar differences were negligible. The specific stacking arrangement of the more elongated 'Conference' pears obstructed vertical airflow in the box causing a larger fruit temperature heterogeneity during cooling than boxes filled with the more spherically shaped 'Durondeau' and 'Doyenné' pears. The variable size and shape of the pear cultivars resulted in a different filling pattern which clearly affected the cooling uniformity, but not the average cooling rate. With the continuous increase and improvement in computational resources, it can be expected that explicit CFD modelling will become the rule instead of the exception. Towards this end, the explicit modelling procedures elaborated in this dissertation have laid the ground works to develop more detailed, realistic and accurate CFD models for postharvest cooling applications. Although focussed on pome fruit, it can easily be extended towards other horticultural produce types where dedicated temperature control schemes during its postharvest life are required. Also other aspects of long-term storage (such as the gas conditioning, postharvest treatments) can be optimised in a more efficient way with the developed models."