Combining homogeneous and heterogeneous chemistry to model inorganic compound concentrations in indoor environments: the H²I model (v1.0)

Homogeneous reactivity has been extensively studied in recent years through outdoor air-quality simulations. However, indoor atmospheres are known to be largely influenced by another type of chemistry, which is their reactivity with surfaces. Despite progress in the understanding of heterogeneous reactions, such reactions remain barely integrated into numerical models. In this paper, a room-scale, indoor air-quality (IAQ) model is developed to represent both heterogeneous and homogeneous chemistry. Thanks to the introduction of sorbed species, deposition and surface reactivity are treated as two separate processes, and desorption reactions are incorporated. The simulated concentrations of inorganic species are compared with experimental measurements acquired in a real room, thus allowing calibration of the model's undetermined parameters. For the duration of the experiments, the influence of the simulation's initial conditions is strong. The model succeeds in simulating the four inorganic species concentrations that were measured, namely NO, NO2, HONO and O3. Each parameter is then varied to estimate its sensitivity and to identify the most prevailing processes. The air-mixing velocity and the building filtration factor are uncertain parameters that appear to have a strong influence on deposition and on the control of transport from outdoors, respectively. As expected, NO2 surface hydrolysis plays a key role in the production of secondary species. The secondary production of NO by the reaction of sorbed HONO with sorbed HNO3 stands as an essential component to integrate into IAQ models.

Combining homogeneous and heterogeneous chemistry to model inorganic compounds concentrations in indoor environments: the H²I model (v1.0)

Homogeneous reactivity has been extensively studied over the past years through outdoor air-quality simulations. However, indoor atmospheres are known to be largely influenced by another type of chemistry, that is reactivity with surfaces. Despite progress in the understanding of heterogeneous reactions, these remain barely integrated in numerical models. In this paper, a room-scale indoor air-quality (IAQ) model is developed to represent both heterogeneous and homogeneous chemistry. Thanks to the introduction of sorbed species, deposition and surface reactivity are treated as two separate processes, and desorption reactions are incorporated. The simulated concentrations of inorganic species are compared to experimental measurements acquired in a real room, thus allowing to calibrate the model's undetermined parameters. For the considered experiments durations, the influence of the simulations initial conditions is strong. The model succeeds in simulating correctly the four inorganic species concentrations that were measured, namely NO, NO2, HONO and O3. Each parameter is then varied to estimate its sensitivity and identify the most prevailing processes. The speed of air and building filtration factor are uncertain parameters which appear to have a strong influence, the first one on deposition, and the second one on the control of transport from outdoor. As expected, the NO2 surface hydrolysis plays a key role in the production of secondary species. The secondary production of NO by the reaction of sorbed HONO with sorbed HNO3 stands as an essential component to integrate in IAQ models.

Combining homogeneous and heterogeneous chemistry to model inorganic compounds concentrations in indoor environments: the H²I model (v1.0)

Homogeneous reactivity has been extensively studied over the past years through outdoor air-quality simulations. However, indoor atmospheres are known to be largely influenced by another type of chemistry, that is reactivity with surfaces. Despite progress in the understanding of heterogeneous reactions, these remain barely integrated in numerical models. In this paper, a room-scale indoor air-quality (IAQ) model is developed to represent both heterogeneous and homogeneous chemistry. Thanks to the introduction of sorbed species, deposition and surface reactivity are treated as two separate processes, and desorption reactions are incorporated. The simulated concentrations of inorganic species are compared to experimental measurements acquired in a real room, thus allowing to calibrate the model’s undetermined parameters. For the considered experiments durations, the influence of the simulations initial conditions is strong. The model succeeds in simulating correctly the four inorganic species concentrations that were measured, namely NO, NO2, HONO and O3, together with the HOx (HO + HO2) radicals. Each parameter is then varied to estimate its sensitivity and identify the most prevailing processes. The speed of air and building filtration factor are uncertain parameters which appear to have a strong influence, the first one on deposition, and the second one on the control of transport from outdoor. As expected, the NO2 surface hydrolysis plays a key role in the production of secondary species. The secondary production of NO by the reaction of sorbed HONO with sorbed HNO3 stands as an essential component to integrate in IAQ models.

Calorie provision from citrate anticoagulation in continuous renal replacement therapy in critical care

Background Citrate is used as a regional anticoagulant for continuous veno-venous haemofiltration and provides 0.59 kcal/mmol. Previous studies hypothesised continuous veno-venous haemofiltration can provide 200–1300 kcal/day dependent on the anticoagulant and replacement solutions used. The aim of this study was to calculate the calorie load from citrate in our patient group. Methods An equation derived from a paper by Oudemans-van Straaten was used to estimate calorie provision from citrate. Citrate calorie load was defined as the difference between the citrate in the filter circuit and the removal by continuous veno-venous haemofiltration. Clinical data were recorded on 20 consecutive patients admitted to intensive care unit and commenced on citrate continuous veno-venous haemofiltration using prismacitrate 18/0 by Gambro, a tri-sodium citrate solution. Clinical data recorded included patient demographics, filter settings including blood flow, filtration factor, citrate dose and time on filtration daily. Results A total of 20 critically ill patients received continuous veno-venous haemofiltration for treatment of a new acute kidney injury, mean age 66 years, 65% male. Mean duration of continuous veno-venous haemofiltration was 3.7 days. Mean daily time on filtration was 20 h/day. Mean filtration fraction, citrate dose and blood flow were 30%, 3 mmol/L and 123 ml/min, respectively. Our calculation showed that a mean of 9.5 ± 1.7 cal/h were provided from citrate with a mean daily calorie load of 196 ± 69 kcal. Conclusions Continuous veno-venous haemofiltration with tri-sodium citrate provided an additional 196 ± 69 kcal/day. The calorie load from citrate continuous veno-venous haemofiltration should be calculated regularly as changes in filter settings, in particular citrate dose and blood flow can have a significant impact on calorie provision.

RESTRICTING GLOBALLY-DEFINED MACKEY FUNCTORS TO NILPOTENT FINITE GROUPS

Let B be the Burnside ring considered as a globally-defined Mackey functor, and k be a field of positive characteristic q. We prove that, when k ⊗ℤ B is restricted to nilpotent groups of order prime to q, the only simple Mackey functors that can appear as subquotients of it are of the form SE,k, where E is the direct product of elementary abelian p-groups. In the special case k = 𝔽2, the simple Mackey functor SE,𝔽2 must appear as a filtration factor in 𝔽2 ⊗ℤ B for every direct product of elementary abelian p-groups E of odd order.

Glomerular and tubular responses toN G-nitro-l-arginine methyl ester are age dependent in conscious lambs

The present experiments were carried out to investigate the role of endogenously produced NO in modulating renal function during postnatal maturation under physiological conditions. In conscious, chronically instrumented lambs aged ∼1 ( n= 8) and ∼6 wk ( n = 8) of postnatal life, various parameters of glomerular and tubular function were measured for 1 h before and 1 h after intravenous injection of 20 mg/kg of N G-nitro-l-arginine methyl ester (l-NAME; experiment 1) or its inactive isomerd-NAME ( experiment 2). After administration ofl-NAME to 1-wk-old lambs, glomerular filtration rate (GFR) and filtration factor (FF) decreased by ∼50% at 20 min, remaining decreased at 60 min. In 6-wk-old lambs, GFR and FF remained constant after l-NAME. Proximal fractional Na+reabsorption decreased after l-NAME administration to lambs aged 6 wk, resulting in a prompt natriuresis; this was sustained for 60 min. There were no effects of l-NAME on proximal fractional Na+ reabsorption in 1-wk-old lambs. In 6-wk-old lambs, urinary flow rate increased by ∼500%, free water clearance increased by ∼50%, and urinary osmolality decreased by ∼60% afterl-NAME administration; no effects on these variables were measured in 1-wk-old lambs. The diuresis after l-NAME administration to 6-wk-old lambs was unaccompanied by any changes in plasma levels of arginine vasopressin. There were no effects ofd-NAME on any of the measured variables. We conclude that endogenously produced nitric oxide modulates glomerular and tubular function in an age-dependent manner.

Renal responses to prolonged (48 h) hypoxemia without acidemia in the late-gestation ovine fetus

The effect of sustained moderate hypoxia on renal blood flow and renal function was studied in the ovine fetus (123–129 days). The experiments consisted of 48 h of isocapnic hypoxia, not resulting in acidemia, but sufficient to produce redistribution of blood flow in favor of the brain at the expense of the carcass. Hypoxemia was induced by maternal nitrogen inhalation. Fetal arterial O2 saturation and arterial O2 pressure ([Formula: see text]) decreased from, respectively, 50.6 ± 3.0% and 17.2 ± 0.9 mmHg during control to 36.4 ± 2.7% and 13.4 ± 0.7 mmHg on the first and to 32.2 ± 2.2% and 12.4 ± 0.7 mmHg on the second day of hypoxemia. Fetal renal blood flow and urine production rate were continuously measured using ultrasonic flow transducers. Fetal renal blood flow increased during hypoxemia from 11.8 ± 1.6 to 15.6 ± 1.8 ml/min and remained elevated throughout the 48-h hypoxemia period ( P < 0.01). Renal blood flow was inversely correlated with fetal [Formula: see text]( r is −0.69, P < 0.0001). Fetal urine production rate, glomerular filtration rate, filtration factor, osmotic clearance, and free water clearance did not significantly change from control values during hypoxemia or recovery. We conclude that hypoxemia without acidemia results in an immediate and considerable increase in fetal renal blood flow, which remains elevated for the entire hypoxemic period.

Characterization of Clotting Factors Associated with Blood Platelets after Gel Filtration

SummaryAggregation of human and rabbit gel filtered platelets (GFP) has been studied in presence of Ca2+, activated factor X (Xa) and different plasma preparations. It was found that factor Xa by itself is not a platelet aggregating agent. However, the platelets aggregated immediately when platelet poor plasma (PPP) was added to a mixture of GFP, Ca2+ and factor Xa. Aggregation also occurred immediately when factor V-deficient plasma was substituted for PPP, but not when factor II-deficient plasma was used. In the absence of factor Xa, aggregation occurred on addition of factor V- or VIII-deficient plasma, but only after some delay. The platelet aggregation experiments and experiments with centrifugations and resuspensions of the platelets, clotting experiments, and gel filtration of platelet free plasma (PEP) led to the following conclusions : Factors II and X are totally removed from the platelets by gel filtration, factor V is closely associated with the platelet surface, and part of the factor VIII-activity in the plasma is eluted together with the GFP without being associated with the platelets. This factor VIII-activity belonged to an extremely large molecule or molecular complex with a Mw in the order of 2 - 5 · 107.