What Is the Optimal Dialysate Sodium Concentration?

In haemodialysis, sodium and fluid balance (where intake matches loss) is achieved by ultrafiltration and by diffusion between the plasma water and dialysate. If a patient’s sodium intake does not change, any reduction in fluid gain obtained by lowering dialysate sodium concentration will result in less sodium removal by ultrafiltration. The corresponding change in diffusion to achieve balance may mean the benefit of lower fluid gain is offset by morbidity caused by a fall in serum sodium during dialysis. The standard dialysate sodium should minimise harm caused by both high ultrafiltration rates and osmotic disequilibrium. For most units, this is likely to be 138 to 140 mmol/L.

Dual vortex breakdown in a two-fluid whirlpool

Looking for an optimal flow shape for culture growth in vortex bioreactors, an intriguing and impressive structure has been observed that mimics the strong swirling flows in the atmosphere (tornado) and ocean (waterspout). To better understand the flow nature and topology, this experimental study explores the development of vortex breakdown (VB) in a lab-scale swirling flow of two immiscible fluids filling a vertical cylindrical container. The rotating bottom disk drives the circulation of both fluids while the sidewall is stationary. The container can be either sealed with the still top disk (SC) or open (OC). As the rotation strength (Re) increases, a new circulation cell occurs in each fluid—the dual VB. In case SC, VB first emerges in the lower fluid at Re = 475 and then in the upper fluid at Re = 746. In case OC, VB first emerges in the upper fluid at Re = 524 and then in the lower fluid at Re = 538. The flow remains steady and axisymmetric with the interface and the free surface being just slightly deformed in the studied range of Re. Such two-VB swirling flows can provide efficient mixing in aerial or two-fluid bioreactors.

Myocardial Expression of Estrogen Receptor-mRNA Is Associated With Lower Markers of Post-operative Organ Damage in Young Patients With Congenital Cardiac Defect

Background: Estrogen receptors (ERs) relate to cardio-protection in adults, but their role in younger patients is not known. We aimed to assess the myocardial expression of ERα- and ERβ- mRNA in young patients with congenital cardiac disease and to analyze their putative protective role.Patients and Methods: Twenty children and young adults (seven females and 13 males) with a median age of 13.8 years (interquartile range: 12.3 years) were enrolled in this prospective study. The myocardial expression of ER-mRNA and genes involved in inflammation, growth, and stress response was assessed by real-time PCR and was correlated to post-operative (po) outcome.Results: ER-mRNA was detected in the myocardium of all patients, independently of gender and age. The expression of ER-mRNA correlated with that of mRNA coding for brain natriuretic peptide and for all cytokines tested. A higher ERα-mRNA expression correlated with lower troponin T concentrations at 24 h po (p = 0.032), higher PaO2/FiO2 ratio at 4 h po (p = 0.059), lower fluid retention at 4 h po (p = 0.048), and lower aspartate aminotransferase (AST) levels at 24 h po (p = 0.047). A higher ERβ-mRNA expression was also correlated with lower fluid retention at 24 h po (p = 0.048).Patients in whom the levels of ERα- and ERβ-mRNA were >P50 had lower troponin T (p = 0.003, respectively) and lower AST concentrations at 24 h po (p = 0.043, respectively) than the others.Conclusions: The expression of ERα- and ERβ-mRNA is present in the myocardium of children and young adults with congenital cardiac defect and is associated with lower markers of po organ damage. This suggests that ERs may provide perioperative organ protection in this population.

Stability Analysis of Thermocapillary Convection of B2O3/Sapphire Melt in an Annular Pool

Aiming at the thermocapillary convection stability of sapphire crystal grown by liquid-encapsulated Czochralski method, by non-linear numerical simulation, obtained the flow function and temperature distribution of R-Z cross section, as well as the velocity and temperature distribution at liquid-liquid interface and monitoring point of B2O3/sapphire melt in annular two liquid system, covered with solid upper wall and in microgravity. By means of linear stability analysis, obtained the neutral stability curve and critical stability parameters of the system, and revealed the temperature fluctuation of the liquid-liquid interface. The calculated results of B2O3/sapphire melt were compared with 5cSt silicone oil/HT-70. The results show that under the same geometrical conditions, the flow of B2O3/sapphire melt system is more unstable than 5cSt silicone oil/HT-70, there are two unstable flow patterns, radial three-dimensional steady flow cell and hydrothermal waves near the hot wall. The larger the ratio of Pr number of upper and lower fluid layers is, the better the effect of restraining the flow of lower fluid layers is.

Urinary Steroid Metabolome Signature is Associated With Cognitive Function in Older Adults

Background: Elevated urine cortisol (<1% of urinary steroid metabolome) was reported to predict future development of dementia. Our objective was to determine the association of urine steroid metabolome and its diurnal variation with cognitive function in men and women. Methods: Cross-sectional study of community-dwelling adults ≥ 50 years. Participants with adrenal disorders, end-stage renal or liver disease, on exogenous steroids or drugs affecting steroid metabolism were excluded. All participants completed day and night separate urine collection. A series of seven IPad-based tests using the National Institute of Health Toolbox Cognition Battery were administered to evaluate five key domains; performance was reported using fully corrected T-scores for age, sex, education, and race with a national normative mean of 50. T-scores were generated for the two summary measures: 1) fluid cognition (includes executive function, episodic memory, working memory, and processing speed), and 2) total composite (composite of fluid and language score). Urine samples were analyzed with the liquid-chromatography, high-resolution, accurate-mass mass spectrometry for 25 urine steroid metabolites. Results: Of 109 participants, 56 (51%) were women, and age and educational status were similar in men and women. On cognitive assessment, men and women had similar median composite cognition (T-score of 53 vs 54, p=0.74) and fluid cognition (T-score of 53 vs 51, p-value 0.96). Urine steroid metabolome analysis demonstrated 21/25 steroids were higher in men vs women. In both women and men, the ratio of total cortisol metabolites/total androgen metabolites (TCM/TAM) was associated with lower fluid cognition (women: ρ= -0.34, p=0.01, men: ρ= -0.43, p=0.001) and composite cognition (women: ρ= -0.27, p=0.04, men: ρ= -0.39, p=0.004). Higher ratio of day to night TCM were associated with a better fluid cognition in men (ρ= 0.35, p=0.01), but not in women (ρ= -0.11, p=0.41). Steroid ratios suggesting a relative enzymatic deficiency of 5α-Reductase type 2 was associated with lower fluid cognition in women (ρ= -0.29, p=0.03). In men, the fluid composite score was associated with a relative deficiency in 21-Hydroxylase (ρ= 0.42, p=0.002), 3β-Hydroxysteroid dehydrogenase (ρ= 0.43, p=0.001), and P450oxidoreductase (ρ= -0.35, p=0.01). Conclusion: We showed that a higher glucocorticoid to androgen ratio and a flattened circadian steroid variation were associated with lower global and fluid cognition score. Steroid ratios reflecting steroidogenesis enzymatic activity demonstrated sex differences in relation to cognition. Additional studies should examine whether the steroid fingerprint associated with lower cognition is predictive of a future dementia onset.

A Brief Review of Gas Migration in Oilwell Cement Slurries

Gas migration in oil and gas wells is defined as gases and/or fluids from adjacent formations invading a freshly cemented annulus. During well completions, gas and/or fluids can migrate to zones with lower pressure or even to the surface. Static gel strength (SGS), related to the yield stress of the cement, is a widely accepted measurement used to predict and minimize gas migration. In this review article, we look at the mechanisms and some possible solutions to gas migration during oil and gas well cementing. The use of static gel strength (SGS) and experimental measurements for SGS and wellbore pressure reduction are discussed. Rheological properties, including the yield stress and the viscosity of cement slurries, are also briefly discussed. Understanding the rheological properties of cement is complex since its material properties depend on cement type, as well as the shape and size distribution of cement particles. From this brief review, it is evident that in order to reduce free water and settling of the cement particles, to lower fluid loss, and to develop compressive strength in the early stages of cementing, an optimal cement slurry design is needed. The SGS test is a standard method used in estimating the free water in the well and could be a reference for gas migration reduction for oilwell cement slurries.

Cognitive segmentation and fluid reasoning in childhood

The ability to solve novel complex problems predicts success in a wide range of areas. Recent research suggests that the ability to cognitively segment complex problems into smaller parts constrains nonverbal reasoning in adults. This study aimed to test whether cognitively segmenting problems improves nonverbal reasoning performance for children as it does for adults. 80 children aged 7-10 years completed two versions of a modified traditional matrix reasoning task in which demands on working memory, integration, and processing speed were minimised, such that the only significant requirement was to break each problem into its constituent parts. In one version of the task, participants were presented with a traditional 2x2 matrix and asked to draw the missing matrix item into a response box below. In a second version, the problem was broken down into its component features across three separate cells, reducing the need for participants to segment the problem. As with adults, performance was better in the condition in which the problems were separated into component parts. Children with lower fluid intelligence did not benefit more in the separated condition than children with higher fluid intelligence, and there was no evidence that segmenting problems was more beneficial for younger than older children. This study demonstrates that cognitive segmentation is a critical component of complex problem-solving for children, as it is for adults. By forcing children to focus their attention on separate parts of a complex visual problem, their performance can be dramatically improved.

Performance of Four Different Nanoparticles in Boundary Layer Flow Over a Stretching Sheet in Porous Medium Driven by Buoyancy Force

This contemporary work explores the theoretical analysis of energy transfer performance of distinct nanoparticles (silver, copper, aluminium oxide and titanium oxide) adjacent to a moving surface under the influence of a porous medium which is driven by the buoyancy force. A mathematical model is presented which is converted to similarity equations by employing similarity transformation. The condensed nonlinear equations were approximated by the iterative method called RKF 45th-order. The flow and energy transference characteristics are explained through graphs and tabulated values. The notable findings are: silver- water is an appropriate nanofluid for enhancing the thermal conductivity of the base fluid. Titanium oxide – water shows a lower fluid flow movement due to porosity.

Albumin Versus Gelatin Solution for the Treatment of Refractory Septic Shock: A Patient Baseline-Matched-Cohort Study

Objective: Although albumin solution is the colloid of choice to resuscitate septic shock patients who do not respond to crystalloid solutions, its usage is limited by its cost. Gelatin solution, is less expensive, but its efficacy has not yet been identified. This study aimed to compare the outcomes of gelatin and albumin solutions for septic shock resuscitation.Methods: This baseline-matched-cohort study, enrolled septic shock patients who had a mean arterial blood pressure (MAP) below 65 mmHg after receiving at least 30 mL per kilogram of crystalloid resuscitation fluid, and who required either an albumin or gelatin solution as fluid therapy. The primary outcome was the 28-day mortality.Results: In all, 224 patients who were administered either an albumin or gelatin solution were examined. After adjusting for differences in their baseline characteristics, 206 patients were included (104 receiving albumin, and 102 given gelatin). A comparison of the albumin and gelatin groups revealed no significant baseline differences in their respective mean APACHE II scores (22.8±8.5vs.23.2±8.1), MAPs (55.1±8.0vs.54.6±9.1mmHg), and lactate levels (5.6±4.7vs.6.3±4.9mmol/L). The 28-day mortality rates were 27.9% and 38.2% for the albumin and gelatin groups, respectively, with adjusted p=0.02. Moreover, the accumulation of fluid intake over output at 72 hours was significantly lower for the albumin than the gelatin group (5,964.5±4,959.7 vs. 8,133.2±3,743.2 ml; p=0.01). The RRT rate was higher for the albumin group (30.8% vs. 15.7%; p=0.01).Conclusion: Albumin resuscitation associated with lower 28-day mortality than gelatin resuscitation. The patients in the albumin group had a higher RRT rate and a lower fluid accumulation as at 72 hours.