Effect of the Number of Nozzles of Swirl Flow Generator Utilized in Flat Plate Solar Collector: An Entropic Analysis

The numerical model of the pipes of a flat plate solar collector (FPSC) with several nozzles has been investigated in the present study. Indeed, the effect of the number of nozzles of the swirl generator on the entropic characteristics has been evaluated. The nozzles were applied for improving the performance of FPSC. For evaluating the proposed system based on the entropy concept, the effect of injection angle and mass flow rate has been considered. The selected injection angles were 30°, 45°, 60°, and 90°. Also, the total mass flow rates entered from all of the nozzles were 0.2 kg/s, 1 kg/s, and 2 kg/s. The effect of said variables on frictional and thermal entropy generations was analyzed; then, the overall energetic-entropic performance of the system was predicted using several dimensionless parameters including NE, NS, Nu ∗ , and heat transfer improvement (HTI). Moreover, Witte-Shamsundar efficiency ( η W − S ) was applied to pinpoint the efficiency of the system. The highest value of HTI and η W − S was 1.7 and 0.9 that achieved by “single-nozzle; A90-D50-N12.5-M0.2” and “quad-nozzle; A30-D50-N12.5-M2,” respectively.

3D Flexible Refinement: Structure and Motion of Flexible Proteins from Cryo-EM

Single particle cryo-EM excels in determining static structures of biological macromolecules such as proteins. However, many proteins are dynamic, with their motion inherently linked to their function. Recovering the continuous motion and detailed 3D structure of flexible proteins from cryo-EM data has remained an open challenge. We introduce 3D Flexible Refinement (3DFlex), a motion-based deep neural network model of continuous heterogeneity. 3DFlex directly exploits the knowledge that conformational variability of a protein is often the result of physical processes that transport density over space and tend to conserve mass and preserve local geometry. From 2D image data, the 3DFlex model jointly learns a single canonical 3D map, latent coordinate vectors that specify positions on the protein's conformational landscape, and a flow generator that, given a latent position as input, outputs a 3D deformation field. This deformation field convects the canonical map into appropriate conformations to explain experimental images. Applied to experimental data, 3DFlex learns non-rigid motion spanning several orders of magnitude while preserving high-resolution details of secondary structure elements. Further, 3DFlex resolves canonical maps that are improved relative to conventional refinement methods because particle images contribute to the maps coherently regardless of the conformation of the protein in the image. Together, the ability to obtain insight into motion in macromolecules, as well as the ability to resolve features that are usually lost in cryo-EM of flexible specimens, will provide new insight and allow new avenues of investigation into biomolecular structure and function.

Performance of EasyBreath Decathlon Snorkeling mask for delivering continuous positive airway pressure

During the COVID-19 pandemic, the need for noninvasive respiratory support devices has dramatically increased, sometimes exceeding hospital capacity. The full-face Decathlon snorkeling mask, EasyBreath (EB mask), has been adapted to deliver continuous positive airway pressure (CPAP) as an emergency respiratory interface. We aimed to assess the performance of this modified EB mask and to test its use during different gas mixture supplies. CPAP set at 5, 10, and 15 cmH2O was delivered to 10 healthy volunteers with a high-flow system generator set at 40, 80, and 120 L min−1 and with a turbine-driven ventilator during both spontaneous and loaded (resistor) breathing. Inspiratory CO2 partial pressure (PiCO2), pressure inside the mask, breathing pattern and electrical activity of the diaphragm (EAdi) were measured at all combinations of CPAP/flows delivered, with and without the resistor. Using the high-flow generator set at 40 L min−1, the PiCO2 significantly increased and the system was unable to maintain the target CPAP of 10 and 15 cmH2O and a stable pressure within the respiratory cycle; conversely, the turbine-driven ventilator did. EAdi significantly increased with flow rates of 40 and 80 L min−1 but not at 120 L min−1 and with the turbine-driven ventilator. EB mask can be safely used to deliver CPAP only under strict constraints, using either a high-flow generator at a flow rate greater than 80 L min−1, or a high-performance turbine-driven ventilator.

Performance of EasyBreath® Decathlon Snorkeling mask for Delivering Continuous Positive Airway Pressure

ABSTRACTBackgroundDuring the COVID-19 pandemic, the need for noninvasive respiratory support devices has dramatically increased, sometimes exceeding hospital capacity. The full-face Decathlon snorkeling mask, EasyBreath® (EB® mask), has been adapted to deliver continuous positive airway pressure (CPAP) as an emergency respiratory interface. We aimed to assess the performance of this modified EB® mask.MethodsCPAP set at 5, 10, and 15 cmH2O was delivered to 10 healthy volunteers with a high-flow system generator set at 40, 80, and 120 L min-1 and with a turbine-driven ventilator during both spontaneous and loaded (resistor) breathing. Inspiratory CO2 partial pressure (PiCO2), pressure inside the mask, breathing pattern and electrical activity of the diaphragm (EAdi) were measured at all combinations of CPAP/flows delivered, with and without the resistor.ResultsUsing the high-flow generator set at 40 L min-1, the PiCO2 significantly increased and the system was unable to maintain the target CPAP of 10 and 15 cmH2O and a stable pressure within the respiratory cycle; conversely, the turbine-driven ventilator did. EAdi significantly increased with flow rates of 40 and 80 L min-1 but not at 120 L min-1 and with the turbine-driven ventilator.ConclusionsEB® mask can be safely used to deliver CPAP only under strict constraints, using either a high-flow generator at a flow rate greater than 80 L min-1, or a high-performance turbine-driven ventilator.

Segmented flow generator for serial crystallography at the European X-ray free electron laser

Serial femtosecond crystallography (SFX) with X-ray free electron lasers (XFELs) allows structure determination of membrane proteins and time-resolved crystallography. Common liquid sample delivery continuously jets the protein crystal suspension into the path of the XFEL, wasting a vast amount of sample due to the pulsed nature of all current XFEL sources. The European XFEL (EuXFEL) delivers femtosecond (fs) X-ray pulses in trains spaced 100 ms apart whereas pulses within trains are currently separated by 889 ns. Therefore, continuous sample delivery via fast jets wastes >99% of sample. Here, we introduce a microfluidic device delivering crystal laden droplets segmented with an immiscible oil reducing sample waste and demonstrate droplet injection at the EuXFEL compatible with high pressure liquid delivery of an SFX experiment. While achieving ~60% reduction in sample waste, we determine the structure of the enzyme 3-deoxy-D-manno-octulosonate-8-phosphate synthase from microcrystals delivered in droplets revealing distinct structural features not previously reported.

Construction and Operation of a Respiration Chamber of the Head-Box Type for Methane Measurement from Cattle

This paper aims to describe the construction and operation of a respiration chamber of the head-box type for methane (CH4) measurements in bovines. The system consists of (1) a head box with a stainless steel frame and acrylic walls, floor, and ceiling; (2) a stainless steel feeder; (3) an automatic drinking water bowl; (4) a hood made from reinforced canvas; (5) an infrared (IR) CH4 gas analyzer, a mass flow generator, a data-acquisition system; and (6) a steel metabolic box. Six assays were conducted to determine the pure CH4 recovery rate of the whole system in order to validate it and comply with standards of chamber operation. The gravimetrical method was used for the recovery test and the recovery rate obtained was 1.04 ± 0.05. Once the system was calibrated, measurements of CH4 were conducted using eight animals consisting of four Holstein cows with a live weight of 593.8 ± 51 kg and an average milk yield of 23.3 ± 1.8 kg d−1 and four heifers with a live weight of 339 ± 28 kg. The CH4 production values were 687 ± 123 and 248 ± 40 L CH4 d−1 for cows and heifers, respectively. The CH4 yield was 19.7 ± 3.4 g and 17.1 ± 3.4 g CH4 kg−1 of dry matter consumed for cows and heifers, respectively. These results are consistent with those reported in the literature.