Ventricular flow analysis and its association with exertional capacity in repaired tetralogy of Fallot: 4D flow cardiovascular magnetic resonance study

Background Four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) allows quantification of biventricular blood flow by flow components and kinetic energy (KE) analyses. However, it remains unclear whether 4D flow parameters can predict cardiopulmonary exercise testing (CPET) as a clinical outcome in repaired tetralogy of Fallot (rTOF). Current study aimed to (1) compare 4D flow CMR parameters in rTOF with age- and gender-matched healthy controls, (2) investigate associations of 4D flow parameters with functional and volumetric right ventricular (RV) remodelling markers, and CPET outcome. Methods Sixty-three rTOF patients (14 paediatric, 49 adult; 30 ± 15 years; 29 M) and 63 age- and gender-matched healthy controls (14 paediatric, 49 adult; 31 ± 15 years) were prospectively recruited at four centers. All underwent cine and 4D flow CMR, and all adults performed standardized CPET same day or within one week of CMR. RV remodelling index was calculated as the ratio of RV to left ventricular (LV) end-diastolic volumes. Four flow components were analyzed: direct flow, retained inflow, delayed ejection flow and residual volume. Additionally, three phasic KE parameters normalized to end-diastolic volume (KEiEDV), were analyzed for both LV and RV: peak systolic, average systolic and peak E-wave. Results In comparisons of rTOF vs. healthy controls, median LV retained inflow (18% vs. 16%, P = 0.005) and median peak E-wave KEiEDV (34.9 µJ/ml vs. 29.2 µJ/ml, P = 0.006) were higher in rTOF; median RV direct flow was lower in rTOF (25% vs. 35%, P < 0.001); median RV delayed ejection flow (21% vs. 17%, P < 0.001) and residual volume (39% vs. 31%, P < 0.001) were both greater in rTOF. RV KEiEDV parameters were all higher in rTOF than healthy controls (all P < 0.001). On multivariate analysis, RV direct flow was an independent predictor of RV function and CPET outcome. RV direct flow and RV peak E-wave KEiEDV were independent predictors of RV remodelling index. Conclusions In this multi-scanner multicenter 4D flow CMR study, reduced RV direct flow was independently associated with RV dysfunction, remodelling and, to a lesser extent, exercise intolerance in rTOF patients. This supports its utility as an imaging parameter for monitoring disease progression and therapeutic response in rTOF. Clinical Trial Registrationhttps://www.clinicaltrials.gov. Unique identifier: NCT03217240.

Water Recovery from Bioreactor Mixed Liquors Using Forward Osmosis with Polyelectrolyte Draw Solutions

This paper reports on the use of forward osmosis (FO) with polyelectrolyte draw solutions to recover water from bioreactor mixed liquors. The work was motivated by the need for new regenerative water purification technologies to enable long-duration space missions. Osmotic membrane bioreactors may be an option for water and nutrient recovery in space if they can attain high water flux and reverse solute flux selectivity (RSFS), which quantifies the mass of permeated water per mass of draw solute that has diffused from the draw solution into a bioreactor. Water flux was measured in a direct flow system using wastewater from a municipal wastewater treatment plant and draw solutions prepared with two polyelectrolytes at different concentrations. The direct flow tests displayed a high initial flux (>10 L/m2/h) that decreased rapidly as solids accumulated on the feed side of the membrane. A test with deionized water as the feed revealed a small mass of polyelectrolyte crossover from the draw solution to the feed, yielding an RSFS of 80. Crossflow filtration experiments demonstrated that steady state flux above 2 L/m2·h could be maintained for 70 h following an initial flux decline due to the formation of a foulant cake layer. This study established that FO could be feasible for regenerative water purification from bioreactors. By utilizing a polyelectrolyte draw solute with high RSFS, we expect to overcome the need for draw solute replenishment. This would be a major step towards sustainable operation in long-duration space missions.

Central Air Conditioning Systems with Partial Indirect Evaporative Cooling and Utilization of Cold and Heat of Ventilation Emissions

A promising trend in air conditioning systems is the use of indirect evaporative cooling, but in the classic version it is effective in dry and hot climates. For the need to maintain comfortable air parameters in public buildings, it is not possible to fully implement such a process in the conditions of Ukraine (the relative humidity of the outside air ranges from 63 to 75 %). The aim of the work is to increase the energy efficiency of air conditioning systems with standard equipment through partial evaporative cooling and use for cooling water in cooling towers of the air removed from the rooms during the warm season, and in the cold season - use of the exhaust air for preheating the supply air in heat exchanger. A corresponding system diagram was developed and computational studies of a direct-flow circuit and a circuit with recirculation were carried out for one of the educational buildings of the Igor Sikorsky Kyiv Polytechnic Institute. According to the results of calculating the direct-flow circuit in the warm period, the energy efficiency of indirect evaporative cooling was 23.5 %. The annual amount of recovered heat of ventilation emissions for this scheme in the cold period was 3731 GJ / year, and the economic effect - 1473185 UAH / year. For a circuit with recirculation during a warm period, the greatest effect of indirect evaporative cooling is achieved with a recirculation rate of 10 %, and for the overall decrease in the cooling capacity of the air conditioner during this period the greatest impact is not indirect evaporative cooling, but recirculation. In the cold season, the greatest utilization effect is also achieved with a 10 % recirculation rate.

Does the Nail Bed Regenerate?

Background: The regenerative potential of the nail bed after trauma remains controversial. Methods: We performed a retrospective review of 51 patients who underwent nail bed reconstruction with 2 techniques (direct flow island flap or a Tranquilli-Leali “Atasoy” flap) due to trauma involving the nail bed complex. These 2 flaps were used to support the loss of distal substance and to allow the regeneration of the nail bed. Outcomes were analyzed for at least 18 months. There were 34 men (66.7%), and the average age was 16.1 years. Most patients (56.9%) had crush injuries. The little (16) and index (14) fingers were the most affected. Twenty-seven were children (range: 4-11) with an average age of 7.4 ± 1.9 years. The middle finger was the most affected (29.2%). Results: The outcomes were good to excellent in 41 operated patients (80.4%). Hook nail was absent in 84.3% of the patients. Most patients (98%) did not develop necrosis. Children had an excellent/good outcome rate of 85.2%, while in adults, the rate was 75% of cases ( P = .485). Conclusion: The direct flow island flap is superior in terms of outcome, regardless of age, sex, affected finger, dominant hand, type of trauma, and injury zone. In cases where there was a correct reconstruction of the hyponychium, there was regeneration of the nail bed.

MODERN DREAMS. PLANNING FIREPLACES

An analysis of the current pace of development of hypersonic technologies for the means of launching spacecraft into Earth orbit, as well as for unmanned weapons systems, which embody both impact properties and reconnaissance functions. In order to better understand the strategic importance of technologies based on direct-flow jet engines, fragmentary coverage of the impressive path of achievements of aerospace technology, given some of the highlights of the history of its formation. The presented article analyzes the current problem - increasing the reliability, reliability and accuracy of the definition and classification of moving targets by autonomous means of aircraft on combat duty. The results of the research cover the features of the starting positions and functional action on the combat duty of aircraft of different classes and bases and are able to serve as a reliable scientific basis for improving military equipment on hypersonic technologies

Mathematical model for calculating the temperature field of a direct-flow drying drum

In this paper, one parabolic-type boundary value problem is solved for determining the temperature field of the raw cotton and air components in drum dryers. In the proposed model, convective heat transfer is used according to Newton’s law, the terms describing the evaporation of moisture from the components of raw cotton (seeds, fiber) and the influence of air velocity are taken into account. The resulting system of Galerkin’s differential equations is solved by the finite-difference method in time. It is shown that the approximate solution is estimated according to Galerkin in Sobolev space.The numerical results of the considered problem are obtained by the Bubnov–Galerkin method. A comparative analysis is carried out with experimental data. It is shown that the proposed mathematical model and its numerical algorithm adequately describe the drying process of raw cotton.

The Multi-Scale Dynamics Organizing a Favorable Environment for Convective Density Currents That Redirected the Yarnell Hill Fire

The deadly shift of the Yarnell Hill, Arizona wildfire was associated with an environment exhibiting gusty wind patterns in response to organized convectively driven circulations. The observed synoptic (>2500 km) through meso-β (approximately 100 km) scale precursor environment that organized a mid-upper tropospheric cross-mountain mesoscale jet streak circulation and upslope thermally direct flow was examined. Numerical simulations and observations indicated that both circulations played a key role in focusing the upper-level divergence, ascent, downdraft potential, vertical wind shear favoring mobile convective gust fronts, and a microburst. This sequence was initiated at the synoptic scale by a cyclonic Rossby Wave Break (RWB) 72 h prior, followed by an anticyclonic RWB. These RWBs combined to produce a mid-continent baroclinic trough with two short waves ushering in cooler air with the amplifying polar jet. Cool air advection with the second trough and surface heating across the Intermountain West (IW) combined to increase the mesoscale pressure gradient, forcing a mid-upper tropospheric subsynoptic jet around the periphery of the upstream ridge over Southern Utah and Northern New Mexico. Convection was triggered by an unbalanced secondary jetlet circulation within the subsynoptic jet in association with a low-level upslope flow accompanying a mountain plains solenoidal circulation above the Mogollon Rim (MR) and downstream mountains.

Left Ventricular Flow Distribution as a Novel Flow Biomarker in Atrial Fibrillation

Introduction: Four-dimensional (4-D) flow cardiac magnetic resonance imaging can be used to elegantly describe the hemodynamic efficiency of left ventricular (LV) flow throughout the cardiac cycle. Patients with nonvalvular paroxysmal atrial fibrillation (PAF) may have occult LV disease. Flow distribution analysis, based on 4-D flow, may unmask the presence of LV disease by assessing flow components: direct flow, retained flow, delayed ejection, and residual volume. This study aimed to identify LV hemodynamic inefficiencies in patients with PAF and normal systolic function. We hypothesized that the fraction of direct flow to the total end-diastolic volume would be reduced in patients with PAF compared with controls.Methods: We used 4-D LV flow component analysis to compare hemodynamics in 30 healthy controls and 50 PAF patients in sinus rhythm.Results: PAF subjects and healthy controls had similar LV mass, volume, and ejection fraction. Direct flow was lower in the PAF group than in the controls (44.5 ± 11.2% vs. 50.0 ± 12.2%, p = 0.042) while delayed ejection was higher in the PAF group (21.6 ± 5.6% vs. 18.6 ± 5.7%, p = 0.022).Conclusion: PAF patients demonstrated a relative reduction in direct flow and elevation in delayed ejection.

Retaining Relative Height Information: An Enhanced Technique for Depression Treatment in Digital Elevation Models

This study presents an enhanced variant of the priority-flood based algorithm proposed by Wang and Liu for treating depressions in digital elevation models (DEMs). The enhanced variant redefines spill elevation, the key concept of the original algorithm, as the lowest elevation that a pixel needs to have to ensure a non-ascending path toward the border of the DEM, plus the larger of a small number (~0.001) and the difference between the unaltered elevation values of the focal pixel and its immediate downhill neighbor. This redefinition is adopted to obtain an intermediate elevation surface to direct flow and ultimately to carve the original DEM. Each carving starts from a depression bottom and propagates downstream until a downhill cell is guaranteed in the original DEM. Tests of these algorithms on a complex terrain of the 260,000 km2 Sichuan structural basin in China shows that the enhanced algorithm maximally preserves the original flow directions and extracts realistic drainage networks. Retaining the relative heights, and therefore flow directions, of cells within depressions allows the new algorithm to offer a depressionless DEM with small modification of its origin for further hydrologic applications. The enhanced depression treatment algorithm is provided as the freely available tool BNUSinkRemv.

Investigation of the direct-flow jets vortex motion in the M-shaped boiler invert furnace

For advanced ultra-supercritical parameters (A-USC) of steam, the design of an M-shaped boiler is proposed, designed to operate in a 500 MW unit on a lean coal (grade TR). The boiler profile is selected from the condition of minimizing the length of the main steamlines made of expensive nickel-alloy steel. With regard to this boiler, a scheme has been developed for pulverized coal combustion in an invert furnace using direct-flow burners and nozzles. Research has been carried out on the physical model of the furnace in the implementation of this combustion scheme: a qualitative study of the trajectories of the burner jets, jets of secondary and tertiary air obtained by their hot spark visualization; quantitative determination of the main characteristics of burner jets and their weight gain. The studies have shown the high efficiency of the recommended scheme of the furnace-burner device: a staged supply of the oxidizer along the flame length and along the furnace height is organized; the dynamic pressure of jets on the furnace wall tubes is excluded; vortex furnace aerodynamics should provide a high degree of burnout of coal dust particles; air jets evenly fill the horizontal section of the furnace; the ejection capacity of turbulent jets is much higher than for a flat submerged jet.