Adjustment Of Flow Rate Research Articles

Technical note: An autonomous flow-through salinity and temperature perturbation mesocosm system for multi-stressor experiments

Abstract. The rapid environmental changes in aquatic systems as a result of anthropogenic forcings are creating a multitude of challenging conditions for organisms and communities. The need to better understand the interaction of environmental stressors now, and in the future, is fundamental to determining the response of ecosystems to these perturbations. This work describes an automated ex situ mesocosm perturbation system that can manipulate several variables of aquatic media in a controlled setting. This perturbation system was deployed in Kongsfjorden (Svalbard); within this system, ambient water from the fjord was heated and mixed with freshwater in a multifactorial design to investigate the response of mixed-kelp communities in mesocosms to projected future Arctic conditions. The system employed an automated dynamic offset scenario in which a nominal temperature increase was programmed as a set value above real-time ambient conditions in order to simulate future warming. A freshening component was applied in a similar manner: a decrease in salinity was coupled to track the temperature offset based on a temperature–salinity relationship in the fjord. The system functioned as an automated mixing manifold that adjusted flow rates of warmed and chilled ambient seawater, with unmanipulated ambient seawater and freshwater delivered as a single source of mixed media to individual mesocosms. These conditions were maintained via continuously measured temperature and salinity in 12 mesocosms (1 control and 3 treatments, all in triplicate) for 54 d. System regulation was robust, as median deviations from nominal conditions were < 0.15 for both temperature (∘C) and salinity across the three replicates per treatment. Regulation further improved during a second deployment that mimicked three marine heat wave scenarios in which a dynamic temperature regulation held median deviations to < 0.036 ∘C from the nominal value for all treatment conditions and replicates. This perturbation system has the potential to be implemented across a wide range of conditions to test single or multi-stressor drivers (e.g., increased temperature, freshening, and high CO2) while maintaining natural variability. The automated and independent control for each experimental unit (if desired) provides a large breadth of versatility with respect to experimental design.

Pneumatic Fault Monitoring and Control for Sustainable Compressed Air Systems

Sustainable development in the industrial sector has been widely explored in recent years, to achieve a carbon-neutral industry. Compressed air systems are widely used in the industrial sector. Numerous energy-saving improvements have been studied within this scope, as leaks make these systems inefficient. Nevertheless, it has yet to be seen how different optimisation techniques can be utilised to mitigate fault effects. This study shows how fault monitoring was performed on a multi-actuator system, using different time domain indicators including, mean and standard deviation. This was followed by exploring the system behaviour when pressure and flowrate control strategies were executed to minimize fault impacts. Fault monitoring, using the indicator data, was successful. For instance, as a 1 mm leak was induced and the consumption increased by 34%, the standard deviation in pressure drop reduced by 6% and the mean actuation time decreased by 13%. Though the mean in pressure drop was useful for fault monitoring other pressure indicators, including standard deviation, provided additional monitoring capabilities. During this monitoring exercise, it was also found that improved sensor accuracy resulted in less reading variations, obtaining more conclusive results and identifying faults of smaller sizes. As faults were accurately identified and characterised, it was then possible to mitigate their effects via pressure and flowrate adjustments. Results proved promising, as both contributed to air consumption decreases of 16% and 11%, respectively. Although such modifications decreased the production rate by 2-5%, the previously mentioned savings outweighed this decrease. This work highlights the need for development of fault monitoring and control systems which maintain the productivity and energy performance of pneumatic systems.

Carbon Capture and Storage Optimization with Machine Learning

This study examines the potential for enhancing carbon capture and storage (CCS) processes by machine learning to markedly improve performance across diverse capture methods, including as absorption, adsorption, membrane separation, and cryogenic distillation. Through the systematic adjustment of critical operating parameters, including temperature, pressure, flow rates, and sorbent characteristics using machine learning algorithms, we saw significant improvements in CO₂ collection efficiency. The use of optimum operating parameters, namely a temperature range of 40-60°C for absorption and a pressure range of 3-5 bar for adsorption, resulted in a 30% enhancement in capture efficiency. Moreover, machine learning models, namely Random Forest and Support Vector Machines (SVM), achieved a maximum enhancement of 20% in forecasting ideal operating parameters for membrane separation and cryogenic systems. Reduced cycle durations in adsorption processes, facilitated by predictive modeling, resulted in a 15% improvement in CO₂ removal rates. The models’ capacity to forecast sorbent regeneration conditions led to a 10% decrease in energy use. Machine learning algorithms adeptly optimized process-specific parameters, including material composition and flow dynamics, enhancing membrane performance by 18% and cryogenic systems by 12%. These results highlight the significance of using machine learning to customize CCS methods for particular materials and situations, facilitating more sustainable, efficient, and scalable carbon capture systems.

One-step flow synthesis of size-controlled polymer nanogels in a fluorocarbon microfluidic chip.

Synthetic polymer nanoparticles (NPs) with biomimetic properties are ideally suited for different biomedical applications such as drug delivery and direct therapy. However, bulk synthetic approaches can suffer from poor reproducibility and scalability when precise size control or multi-step procedures are required. Herein, we report an integrated microfluidic chip for the synthesis of polymer NPs. The chip could sequentially perform homopolymer synthesis and subsequent crosslinking into NPs without intermediate purification. This was made possible by fabrication of the chip with a fluorinated elastomer and incorporation of two microfluidic mixers. The first was a long channel with passive mixing features for the aqueous RAFT synthesis of stimuli-responsive polymers in ambient conditions. The polymers were then directly fed into a hydrodynamic flow focusing (HFF) junction that rapidly mixed them with a crosslinker solution to produce NPs. Compared to microfluidic systems made of PDMS or glass, our chip had better compatibility and facile fabrication. The polymers were synthesized with high monomer conversion and the NP size was found to be influenced by the flow rate ratio between the crosslinker solution and polymer solution. This allowed for the size to be predictably controlled by careful adjustment of the fluid flow rates. The size of the NPs and their stimuli-responses were studied using DLS and SEM imaging. This microfluidic chip design can potentially streamline and provide some automation for the bottom-up synthesis of polymer NPs while offering on-demand size control.

Analysis of the Sum Minimization Possibilities of Heat Exchanger Core Masses in Internal Combustion Engine Cooling Systems

Rational designs for cooling systems (CS) of internal combustion engines are formulated in the form of a series of circulation circuits. The engine is integrated into a circuit with the highest and unregulated flow of internal circuit coolant (ICC). All heat exchangers are placed in circulation circuits with relatively reduced and adjustable ICC flow rates. While the circuits are usually interconnected, they can also be designed to operate independently. This CS scheme enables the achievement of the minimum possible value of the sum of masses of exchanger cores, denoted as MΣ. The reduction in MΣ is achieved through the regulation of ICC flow in a closed circulation loop involving two heat exchangers. The variations in MΣ based on the circuit parameters have been thoroughly investigated. The reduction in MΣ can also be applicable to more intricate systems. A decrease in MΣ, under identical initial CS parameters, may occur in different magnitudes, depending on the specific features of the CS scheme and the operating conditions of the heat exchangers within it. Cooling systems, constructed with the same initial parameters and comprising multiple circulation circuits that meet all criteria for rational design, may exhibit diverse configurations. Examples of such systems are explored, and the minimum values of MΣ are calculated for each. It has been determined that the disparity in the minimum values of MΣ for such systems, while maintaining equal efficiency, can exceed 30%. The selection of the optimal CS scheme is contingent not only on achieving the minimum possible value of MΣ but also on various other factors.

The effect of magnetic field variations on the spectral properties of tornado plasma

At atmospheric pressure and at a frequency of 9.1 kHz, a constructed magnetically stabilized tornado gliding arc discharge (MSGAD) system was utilized in this study to generate a non-thermal plasma with an alternating voltage source from 2,4,6,8 to 10 kV. Argon gas was used to generate the arc plasma with an adjustable flow rate using a flow meter regulator to stabilize the gas flow rate to 2 L/min. A gliding plasma discharge is achieved by a magnetic field for the purpose of a planned investigation. The influence of the magnetically stabilized tornado gliding arc discharge parameters such as magnetic field and applied voltage on microscopic tornado plasma parameters was studied. The electron temperature1was measured using a Boltzmann plot and the electron1density was1determined by the Stark1broadening method. The electron temperature ranged from 0.818 eV to 1.495 eV, and the electron density varied from 1.37 × 1018 cm−3 to 2.49 × 10 18 cm−3 at a magnetic coil with 350 turns. Subsequently, the electron temperature increased to a range of 1.029 eV–1.794 eV, and the electron density reached a range of 1.53 × 1018 cm−3 to 2.89 × 1018 cm−3 at a magnetic coil with 500 turns. It can be observed that the plasma properties exhibit a rise as the number of turns of the coil and the applied voltage increase.

A flow-rate-aware data-driven model of vanadium redox flow battery based on gated recurrent unit neural network

The vanadium redox flow battery (VRB) system involves complex multi-physical and multi-timescale interactions, where the electrolyte flow rate plays a pivotal role in both static and dynamic performance. Traditionally, fixed flow rates have been employed for operational convenience. However, in today’s highly dynamic energy market environment, adjusting flow rates based on operating conditions can provide significant advantages for improving VRB energy conversion efficiency and cost-effectiveness. Unfortunately, incorporating the electrolyte flow rate into conventional multi-physical models is overly complex for VRB management and control systems, as real-time operations demand low-computational and low-complexity models for onboard functionalities. This paper introduces a novel data-driven approach that integrates flow rates into VRB modeling, enhancing data processing capabilities and prediction accuracy of VRB behaviors. The proposed model adopts a gated recurrent unit (GRU) neural network as its fundamental framework, exhibiting exceptional proficiency in capturing VRB’s nonlinear voltage segments. The GRU network structure is carefully designed to optimize the predictive ability of the model, with flow rate considered as a crucial input parameter to account for its influence on VRB behavior. Model refinement involves analyzing well-designed simulation results obtained during VRB operations under various flow rates. Laboratory experiments were also designed and conducted, covering different conditions of currents and flow rates to validate the proposed data-driven modeling method. Comparative analyses were performed against several state-of-the-art algorithms, including equivalent circuit models and other data-driven models, demonstrating the superiority of the proposed GRU-based VRB model considering flow rates. Thanks to the GRU’s outstanding capability in processing time series data, the proposed model delivers impressively accurate terminal voltage predictions with a low error margin of no more than 0.023 V (1.3%) under wide operating ranges. These results indicate the efficacy and robustness of the proposed approach, highlighting the novelty and significance of accounting for flow rates in accurate VRB modeling for management and control system design.

Passive control of flow rate change due to the input pressure fluctuation based on microchannel deformation

Precise and controlled drug delivery is crucial in continuous infusion systems used for drug treatment, anesthesia, cancer chemotherapy, and pain management. Elastometric pumps are commonly utilized in continuous infusion systems for their ease of use and cost-effectiveness. However, the infusion accuracy is often compromised due to the fluctuating supply pressure of elastomeric pumps, requiring an additional flow regulator to stabilize the output flow rate. We, here, present a novel approach to passively control a flow rate even under the fluctuating pressure environment based on a channel deformation. The flow rate control is enabled by a flow regulator consisting of an open-end microchannel, a closed-end microchannel, and a flexible membrane in the middle. The pressure within an open-end microchannel decreases in the downstream direction, while the pressure within a closed-end microchannel remains equal to the input pressure, creating the pressure difference between the two channels. The membrane deforms in response to this pressure difference, allowing for adjustment of the output flow rate by decreasing the flow path area with the increase in the input pressure. It is found that this concept successfully works by maintaining a steady output flow rate over a target pressure range of 40–50 kPa. Fluid–structure interaction numerical simulations and theoretical analysis are used to explain the flow rate control mechanism of the device. The results show that the present approach offers a promising solution for achieving stable drug delivery in continuous drug infusion systems, addressing the limitations of conventional elastomeric pumps.

Integration of Artificial Intelligence for Real-Time Fault Detection in Semiconductor Packaging

Semiconductor manufacturing involves a complex sequence of unit processes, where even a minor error can disrupt the entire production chain. Present-day manufacturing setups rely on continuous data monitoring of equipment health, wafer measurements, and inspections to identify any abnormalities that could impact the quality and performance of the final chip. The primary aim is fault detection and classification (FDC), for which a range of techniques including statistical analysis and machine learning algorithms are commonly employed. In this study, we introduce an innovative approach utilizing an artificial immune system (AIS), inspired by biological mechanisms, for FDC in semiconductor equipment. The main culprits behind process failures are shifts caused by the aging of parts and modules over time. Our methodology integrates state variable identification (SVID) data, reflecting current equipment conditions, and optical emission spectroscopy (OES) data, capturing plasma process information under faulty scenarios induced by deliberate gas flow rate adjustments in semiconductor fabrication. Our results demonstrate a modeling prediction accuracy of 94.69% when incorporating selected SVID and OES data, and 93.68% accuracy using OES data alone. In conclusion, we suggest the potential application of AIS in semiconductor process decision-making, offering promising avenues for enhancing fault detection in semiconductor equipment.

Impact and analysis of urban water system connectivity project on regional water environment based on Storm Water Management Model (SWMM)

SWMM stands as a dynamic rainfall-runoff urban hydrological model, crafted by the U.S. Environmental Protection Agency. It adeptly replicates urban rainfall production and ground runoff, and the Pressure-State-Response (PSR) theory artfully reflects human-environment interactions. Urban Water System Connectivity (UWSC) fortifies connections among regional rivers, transforming them into an intricate, dense network. To study the improvement of the regional water environment by the UWSC project, this study takes the UWSC project in Runan County, Zhumadian, China as the research object, constructs a hydrodynamic and water quality model based on SWMM, and simulates it under different rainfall situations. At the same time, the ecological service value theory and PSR theory are used to establish an ecological effect index system to analyze the ecological effect before and after the UWSC project. This paper evaluates the urban water system connectivity project from three aspects: hydrodynamic, water quality, and ecological effects. Results underscore that the post-UWSC era witnesses decreased river flood flows in varied design rainfalls, accompanied by delayed flood peaks. Under P = 10a and P = 20a rainfalls, peak flow reductions of 6.6% and 4.96% respectively, manifest with peak time lags of 0.17h. Flow rate adjustments align with flow behavior, exhibiting decreased peak flow rates accompanied by temporal lags. Initial river flow increases by about 30%, amplifying river water body exchange capacity. Following the UWSC implementation, the study area's five primary rivers display TSS reductions ranging from 46% to 86.94%, COD from 36.98% to 92.43%, TN from 45.9% to 92.96%, TP from 35.71% to 84.78%, and NH3–N from 38.52% to 92.19%. Simulated point source pollution, under comparable initial conditions, indicates pollutant decay rates escalating from 3.2%–20%–35.71%–92.43%. Ecological impact ascends from 6.33 × 108 RMB to 9.65 × 108 RMB, reflecting a 52.5% escalation. The UWSC initiative enriches urban river flood resilience and water quality, emblematic of urban water ecological civilization progress.

High-throughput synthesis of high-purity and ultra-small iron phosphate nanoparticles by controlled mixing in a chaotic microreactor

High-purity FePO4 with small particle size is pivotal for improving electrochemical performance of LiFePO4-based lithium-ion batteries. Here, an oscillating feedback microreactor (OFM) based on chaotic advection was designed to prepare high-quality FePO4 by coprecipitation. Dye-tracer experiments and CFD simulations were adopted to investigate fluid mixing mechanism and to evaluate mixing efficiency in the reactor. The results indicated that a “flow-focused” OFM (FOFM) performed better than a “Y-junction” OFM in mixing performance, owing to enhanced premixing in focused inlet microchannel of the former. The results of Villermaux-Dushman experiments illustrated that almost complete mixing could be achieved in 0.16 ms in FOFM. Accordingly, FePO4 nanoparticles of good quality was synthesized using FOFM, and the particle size can be easily controlled by adjusting flow rate or reactant concentration. High-purity (P/Fe molar ratio: 0.95–1.04) and ultra-small FePO4 nanoparticles (9 nm) with narrow particle size distribution were generated at a high throughput of 180 mL/min.

Impact of the Lubricant on a Modified Revolving Vane Expander (M-RVE) in an Organic Rankine Cycle System

The expansion device is the critical component of micro-to-small scale organic Rankine cycle (ORC) systems, substantially affecting system efficiency and cost. Low isentropic efficiency and lubrication requirements are the main issues associated with using volumetric expanders in ORC systems. Despite lubrication contributing to reducing internal leakages in an expander, it may compromise the performance of the ORC system by adversely affecting the evaporator’s thermal capacity. This study tests a recently developed and modified revolving vane expander (M-RVE) in a micro-scale ORC test rig by implementing an adjustable oil mass flow rate. The impact of the lubricant oil on the performance of the M-RVE prototype is investigated within a wide range of oil circulation rates (OCR). The results demonstrate a negligible improvement in the filling factor for OCRs higher than 1%. Moreover, the shaft power is not considerably sensitive to OCR, while the calculated isentropic efficiency of the expander improves with OCR. Furthermore, the impact of the lubricant oil on the performance of the evaporator is studied, assuming the exact OCR as the expander and measured temperature and pressure similar to the pure refrigerant for the lubricant-refrigerant mixture in the evaporator. The study shows that the evaporator capacity is penalized with OCR, especially for values higher than 1%. Hence, an OCR of about 1% is a good compromise, and it can be used as a guideline for designing revolving vane expanders for micro-scale ORC systems without a dedicated lubricant oil circuit.

P-042 Sperm Selection Based on Speed Using Rheotaxis in a Parallel Array of Microfluidic Apertures

Abstract Study question Does selecting human spermatozoa using a dynamic microfluidic system impact semen parameters and genomic characteristics? Summary answer Flow rate adjustment in a dynamic microfluidic device selects spermatozoa with superior DNA integrity. It also appears to select a higher proportion of Y-chromosome-bearing spermatozoa. What is known already Mammalian spermatozoa demonstrate rheotactic motion against the flow. This is important in order to overcome the fluid drag force in the female genital tract to reach the oocyte. Sperm processing methods have been developed based on these principles; more recently, static and dynamic microfluidic devices have been tested due to the association between high progressive motility and greater genomic integrity. These devices also appear to have an impact on sperm sex selection. Study design, size, duration Human ejaculates (n = 7) were evaluated and simultaneously processed by density gradient centrifugation (DGC) or a novel microfluidic sperm sorter (MFSS) with an adjustable flow rate inspired by the constriction of the uterotubal junction. Concentration, motility, morphology, and SCF were assessed and compared between raw, DGC-, and MFSS-processed specimens. To identify differences in the SCF and the proportion of X- and Y-spermatozoa, spermatozoa isolated at different flow rates (150, 250, 350, and 450 μl/h) were evaluated. Participants/materials, setting, methods Ejaculates were evaluated by standard semen analysis according to WHO 2021 criteria. Following complete liquefaction, 1 mL of sample was used for DGC, and 0.8 mL of semen was used for the prototype MFSS at 0.2 mL for each flow rate. SCF was assessed by TUNEL assay with a normal threshold of ≤ 15%. Fluorescent in situ hybridization (FISH) was performed using X- and Y-chromosome probes. Main results and the role of chance A total of 7 men (35.4±5 years) had the following semen parameters: volume of 3.3±2 mL, concentration of 76.7±33 x106/mL, 45.5±1% motility, and a normal morphology of 3.2±0%. When comparing the post-processing parameters between the two methods, DGC yielded a concentration of 49.9±25 x106/mL and MFSS yielded a reduced concentration of 4.5±5x106/mL (P<0.0001). DGC yielded 91.1±1% motility and normal morphology of 3.2±0.4%. Albeit at a cost of concentration, MFSS yielded spermatozoa with significantly higher motility (96.3±3%; P<0.0001) and a higher proportion with normal morphology (4.0±0.6%; P<0.0001). Moreover, the SCF of the raw sample was 9.4±2.0%; although the SCF was 8.1±3.6% with DGC, it was 4.5±2% (P<0.001) with MFSS. An analysis was performed within the different flow rates of the MFSS; a 250 μl/h flow rate yielded the highest recovery rate (42.0±6%; P<0.001), highest concentration (5.6±4 x106/mL; P<0.01), highest motility (97.0±2.2%; P<0.05), and a normal morphology rate (4.3±1%). The SCF for this flow rate was <3%. Surprisingly, we noticed that the proportion of Y-chromosome–bearing spermatozoa positively correlated to the flow rate, suggesting that there may be a subtle difference in the kinetics of male and female spermatozoa. Limitations, reasons for caution Although our novel MFSS platform is a promising technique, it is costly and requires specific expertise and training. This is a limited observation and requires integration of clinical outcomes to prove its benefits. Wider implications of the findings A microfluidic device with a controlled flow rate allowed the fine-tuned selection of spermatozoa with superior hydrodynamic and kinetic characteristics and a higher genomic integrity. Once automated, this device may help to select spermatozoa with greater embryo developmental competence and be useful to isolate spermatozoa of the desired sex. Trial registration number N/A

A comprehensive evaluation of hemodynamic energy production and circuit loss using four different ECMO arterial cannulae.

Pulsatile-flow veno-arterial extracorporeal membrane oxygenation (V-A ECMO) has shown encouraging results for microcirculation resuscitation and left ventricle unloading in patients with refractory cardiogenic shock. We aimed to comprehensively assess different V-A ECMO parameters and their contribution to hemodynamic energy production and transfer through the device circuit. We used the i-cor® ECMO circuit, which composed of Deltastream DP3 diagonal pump and i-cor® console (Xenios AG), the Hilite 7000 membrane oxygenator (Xenios AG), venous and arterial tubing and a 1 L soft venous pseudo-patient reservoir. Four different arterial cannulae (Biomedicus 15 and 17 Fr, Maquet 15 and 17 Fr) were used. For each cannula, 192 different pulsatile modes were investigated by adjusting flow rate, systole/diastole ratio, pulsatile amplitudes and frequency, yielding 784 unique conditions. A dSpace data acquisition system was used to collect flow and pressure data. Increasing flow rates and pulsatile amplitudes were associated with significantly higher hemodynamic energy production (both p < 0.001), while no significant associations were seen while adjusting systole-to-diastole ratio (p = 0.73) or pulsing frequency (p = 0.99). Arterial cannula represents the highest resistance to hemodynamic energy transfer with 32%-59% of total hemodynamic energy generated being lost within, depending on pulsatile flow settings used. Herein, we presented the first study to compare hemodynamic energy production with all pulsatile ECLS pump settings and their combinations and widely used yet previously unexamined four different arterial ECMO cannula. Only increased flow rate and amplitude increase hemodynamic energy production as single factors, whilst other factors are relevant when combined.

Design and Characterization of an Adjustable Passive Flow Regulator and Application to External CSF Drainage

Passive valves that deliver a constant flow rate regardless of inlet pressure changes have numerous applications in research, industry, and medical fields. The present article describes a passive spring valve that can be adjusted manually to deliver the required flow rate. The valve consists of a movable rod with an engraved microchannel. The fluidic resistance of the device varies together with the inlet pressure to regulate the flow rate. A prototype was made and characterized. Flow-rate adjustment up to +/-30% of the nominal flow rate was shown. A simple numerical model of the fluid flow through the device was made to adapt the design to external ventricular drainage of cerebrospinal fluid (CSF). Some insights about the implementation of this solution are also discussed.

Clinical review of high-flow nasal oxygen therapy in human and veterinary patients.

Oxygen therapy is the first-line treatment for hypoxemic acute respiratory failure. In veterinary medicine this has traditionally been provided via mask, low-flow nasal oxygen cannulas, oxygen cages and invasive positive pressure ventilation. Traditional non-invasive modalities are limited by the maximum flow rate and fraction of inspired oxygen (FiO2) that can be delivered, variability in oxygen delivery and patient compliance. The invasive techniques are able to provide higher FiO2 in a more predictable manner but are limited by sedation/anesthesia requirements, potential complications and cost. High-flow nasal oxygen therapy (HFNOT) represents an alternative to conventional oxygen therapy. This modality delivers heated and humidified medical gas at adjustable flow rates, up to 60 L/min, and FiO2, up to 100%, via nasal cannulas. It has been proposed that HFNOT improves pulmonary mechanics and reduces respiratory fatigue via reduction of anatomical dead space, provision of low-level positive end-expiratory pressure (PEEP), provision of constant FiO2 at rates corresponding to patient requirements and through improved patient tolerance. Investigations into the use of HFNOT in veterinary patients have increased in frequency since its clinical use was first reported in dogs with acute respiratory failure in 2016. Current indications in dogs include acute respiratory failure associated with pulmonary parenchymal disease, upper airway obstruction and carbon monoxide intoxication. The use of HFNOT has also been advocated in certain conditions in cats and foals. HFNOT is also being used with increasing frequency in the treatment of a widening range of conditions in humans. Although there remains conflict regarding its use and efficacy in some patient groups, overall these reports indicate that HFNOT decreases breathing frequency and work of breathing and reduces the need for escalation of respiratory support. In addition, they provide insight into potential future veterinary applications. Complications of HFNOT have been rarely reported in humans and animals. These are usually self-limiting and typically result in lower morbidity and mortality than those associated with invasive ventilation techniques.

РЕЗУЛЬТАТЫ ИССЛЕДОВАНИЙ АЭРОДИНАМИЧЕСКИХ СВОЙСТВ ЗЕРНОВЫХ МАТЕРИАЛОВ

The aerodynamic properties of the components of the grain pile during its post-harvest processing are one of the most important parameters affecting the quality of the resulting grain and seeds. Existing devices are considered that allow establishing the speed of soaring of grain materials, their shortcomings and limitations are noted. A sail pneumatic classifier has been developed that provides smooth adjustment of the air flow rate and high accuracy of its measurement. Experimental studies have been carried out to establish polygons for the distribution of soaring speeds for a number of grain materials using the developed classifier. It has been established that the ranges of soaring speeds for different crops differ significantly. The soaring speed ranges for wheat and bindweed buckwheat do not intersect, which allows them to be completely separated using an air flow at a speed of 5.91-8 m/s. The soaring speed of sorghum (8.37-10.02 m/s) is completely covered by the range of this indicator for wheat, so it is not possible to separate them using aspiration systems. The ranges of critical rates of millet, vetch and wheat partially intersect, which indicates the impossibility of complete separation of these impurity components without loss of grain of the main crop. At an air flow rate of 9 m/s, 96.9% of the impurity component will be released from the wheat-millet grain mixture with technological losses of the main crop at the level of 4%. Even with a slight increase in the air flow rate, a significant increase in wheat losses is inevitable. Vetch can be completely separated from wheat at an air speed of 11 m/s with a loss of 1.8% of wheat. The results of the performed studies are necessary to improve the efficiency of the use of pneumatic separating equipment through the use of reasonable rational operating modes.

Gas-phase dopant flow to modify nanoLC-MS and nanoESI protein charge

A miniature permeation device is used to add controlled amounts of gas-phase dopant to the air around two types of atmospheric pressure nanoflow electrospray source: a pulled glass capillary needle in a custom mount, and for the first time a commercial nano-liquid chromatography emitter in a commercial ion source housing. Intact proteins sprayed at 300 nL/min are charge-reduced by the addition of nitrogen doped with diethylamine, and the reaction is assisted by adjusting flow rate, positioning, and enclosure of the nanoflow emitter. Charge distribution is shifted to lower charge states with increasing amounts of dopant. The maximum signal of the most abundant charge state and the total signal abundance are increased to an extent dependent on the mass and isoelectric point of the protein.

Flow Regulation of Low Head Hydraulic Propeller Turbines by Means of Variable Rotational Speed: Aerodynamic Motivations

To date, hydraulic energy is still, among the renewable ones, the most widespread and most exploited to produce electricity. With the current trend to exploit any renewable source available, the limits for the economic convenience of hydroelectric power plants have significantly changed, making it interesting and convenient to use even small heads and low flow rates. In the specific applications of hydraulic turbines operating with low heads, the Kaplan turbine plays the predominant role among the available machines, also given the possibility of carrying out an “on cam” regulation, acting simultaneously on the geometry of the rotor and distributor rows, thus allowing a wide flow rate adjustment range. However, for applications characterized by very low heads and low available powers, it may not be convenient to use complex regulating devices. For this reason, these plants usually use axial machines characterized by a partial regulation (of the distributor or of the rotor), significantly reducing the operating range of the machine compared to the case of double regulation. In the last decade, the development of reliable and less expensive permanent magnet generators and power electronic converters and related new control strategies has paved the way for the concept of regulating hydraulic turbines by means of variable rotational speed. This regulation principle is based on the possibility of acting in the case of using synchronous permanent magnets electric generators and electronic power converters and on the variation of the rotational speed of the machine while keeping the grid frequency constant. The concept can be applied both to pure propellers with fixed a rotor and fixed distributor and to hydraulic axial turbines with regulation based on the modification of the variable guide vane opening angle. Although this new regulation approach, even in the case of the combined guide vane and rotational speed regulation, does not allow to recover most of the energy losses due to the variation of the operating conditions as effectively as the Kaplan double regulation does, the variation of the rotation speed, coupled with the variation of the opening of the distributor row, allows to reduce the tangential kinetic energy losses generated at the turbine exit during the off-design operations of a fixed blade opening angle rotor. At the same time, this type of regulation offers a simple and thus low-cost solution. The present study develops the theory underlying this regulation concept, based on the use of the turbomachinery fundamental equations, and reports the results of the off-design CFD analysis carried out for different combinations of rotation speeds and openings of the distributor, showing the improvement of the hydraulic efficiency over a large range of operating conditions with respect to the single regulation approach.

Centrifugal partition chromatography as a potential method of isolation and purification of amphiphilic substances from a solid-state fermentation process

Separating amphiphilic compounds from complex matrix is challenging. Surfactin, cyclic lipopeptides group, was used as a model to find the proper separation conditions and parameters. The aim of the work was to solve the emulsification plug problem in countercurrent partition chromatography (CPC). The selected solvent system was a composition of n-heptane/n-butanol/methanol/aqueous buffer (20 mM disodium phosphate with 50 mM NaCl) at a ratio of 2:3:2:3. Several elution method modifications were applied. The most important was an appropriate mobile phase flow rate adjustment (flow rate gradient), minimizing the risk of stationary phase leakage. During the CPC procedures, the hydrostatic pressure was monitored as a factor of stationary phase retention. The hydrostatic pressure indicated the biphasic system’s stability. A flow rate of 2 ml/min resulted in column stabilization and peak resolution during chromatographic separation. In order to avoid uncontrolled leakage, the flow rate was increased gradually. At 3.5 ml/min, there was a small loss of the stationary phase as the hydrostatic pressure decreased from 32 to nearly 18 bar. After designing the method, it was tested with SU containing extracts obtained from SSF to show its effectiveness. Our results showed that the single dual-mode method can be used to remove matrix’s impurities and separate surfactin as a mixture of homologues with more than 80% purity. Moreover, application of the double dual-mode method allows for the isolation of fractions containing individual surfactin homologues in amounts of about 70% of the sample, which makes it possible to conduct further biological research.