Use Of Airflow Research Articles

Human coronavirus 229E inactivation on porous and nonporous materials using dielectric barrier discharge (DBD) plasma.

Viruses can spread through contaminated aerosols and contaminated surface materials, and effective disinfection techniques are essential for virus inactivation. Nonthermal plasma-generated reactive oxygen and nitrogen species can effectively inactivate the coronavirus. We aim to interpret the coronavirus inactivation level and mechanism of surface interaction with materials with and without dielectric barrier discharge (DBD) plasma treatment. Nonthermal plasma, particularly surface-type DBD plasma, can inactivate human coronavirus 229E (HCoV-229E) on porous (paper, wood, mask) and nonporous (plastic, stainless steel, glass, Cu) materials. Virus inactivation was analyzed using a 50% tissue culture infectivity dose (TCID50) using cell line, flow cytometry, and immunofluorescence. Surfaces contaminated with HCoV-229E were treated at different time intervals (0-5 h) with and without plasma exposure (natural decay in ambient air conditions). HCoV-229E persistence conformed to the following order: plastic > cover glass > stainless steel > mask > wood > paper > Cu with and without plasma exposure. HCoV-229E was more stable in plastic, cover glass, and stainless steel in 5 h, and the viable virus titer gradually decreased from its initial log10 order of 6.892 to 1.72, 1.53, and 1.32 TCID50/mL, respectively, under plasma exposure. No virus was observed in Cu after treatment for 5 h. The use of airflow, ambient nitrogen, and argon did not promote virus inactivation. Flow cytometry and immunofluorescence analysis demonstrated a low expression level of spike protein (fluorescence intensity) during plasma treatment and in E and M genes expression compared with the virus control.

Formation and steady state characteristics of flow field effect in the header of a stripping prior to cutting combine harvester with CFD

In order to analyze the formation mechanism of the flow field in the header of a stripping prior to cutting combine harvester and compare the steady characteristics of the flow field generated by flat and concave combs, this study combined bench tests and computational fluid dynamics (CFD) to analyze them. During the formation of the flow field, the airflow produced “bottoming out” and “vortex” and other phenomena. At high speed, the maximum velocity of the airflow generated by the flat comb was 10.39 m s−1 and that of the concave comb was 10.59 m s−1; the flow field generated by the concave comb was better than that generated by the flat comb. Significant pulsation effects were generated in the airflow at the rice inlet and return outlet; the pulsation intensity was positively correlated with the pulsation mean velocity. At the return outlet, the turbulence of the airflow generated by the concave comb rotation was higher than that of the airflow generated by the flat comb rotation for both low and high speed conditions. This study explores the characteristics of stripping loss in the header of a stripping prior to cutting combine harvester from the perspective of flow field, which provides ideas for the structural optimization of a stripping prior to cutting combine harvester and the study of stripping loss reduction in the later stage, and also provides a reference for the rational use of air flow in the rotating domain in engineering applications.

Evaluation of the Effects of Airflow Patterns on Human Thermal Perception

Recently, greenhouse gas emissions have led to irreversible climate change, and in order to mitigate the changes, more and more research is focusing on energy efficiency and environmental protection in the building sector. Improving indoor ventilation airflow as a feasible solution for energy conservation as well as improving human thermal comfort. This study aims to provide reference for optimizing the thermal perception of occupants in indoor ventilation design. This research evaluates the effect of heat perception on students in a stable indoor environment (28 ℃, RH 50%) under two airflow patterns (dynamic and constant). The use of airflow was found to have a positive impact on thermal sensation vote (TSV) and thermal pleasure vote (TPV). There was non-significant difference in the effects of heat perception between airflow modes. This finding is consistent with the findings of Parkinson and de Dear's study. It is worth noting that differences in experimental results may be due to other personal factors (e.g., gender, age, and weight). Further studies are therefore needed to demonstrate the influence of these factors on the thermal perception effect of air movement.

Experimental Investigation of Dropwise Condensation Shedding by Shearing Airflow in Microgravity Using Different Surface Coatings.

The shedding kinematics of water droplets in a condensation environment when exposed to aerodynamic forces in microgravity was studied. Understanding the shedding of droplets from a surface is a critical part of the dropwise condensation process for improving heat transfer. Because gravity as a droplet removal technique is not available in space, the use of airflow to shed droplets is considered for condensing heat exchangers in environmental control and life support systems. Surface coatings affect drop adhesion, and here, four different surfaces (PMMA, PS, PTFE, and SHS) and various droplet sizes (80, 60, and 40 μL) were used to understand the above phenomenon. It was found that the critical velocity to shed a droplet in microgravity was up to 8% lower than that in normal gravity. Also, the effect of the droplet size was investigated for both microgravity and normal gravity; the shedding velocity was lower for microgravity, and it decreased as droplet size increased. Increasing the hydrophobicity of the coating decreased the critical velocity for shedding. Finally, the droplet was found to detach from superhydrophobic surfaces in microgravity. The detachment of droplets from the substrate will hamper the condensation process that can produce a larger fresh area; also, detachment of droplets and entrainment in airflow counter the concept of removing moisture from the air in a dehumidification process.

Common practices of dental implants maintenance among dental hygiene professionals in Israel and Germany.

The aim of this study was to assess the common practices of dental implant maintenance among dental hygiene professionals (DHP) in Israel (IL) and Germany (GE). An online questionnaire was developed by the Periodontology Departments of Tel Aviv (IL) and Frankfurt University (GE) to address demographics, training, prevention and treatment of peri-implant diseases. The questionnaire was distributed by DHP associations via social media. The responses of 376 DHPs (IL: 169; GE: 207) were analysed. Most participants were female (IL: 168/99%; GE: 203/98%), had received education (IL: 179/97%; GE: 207/97%) and were working in their home countries (IL: 182/99%; GE: 211/99%). Peri-implant probing was not performed by 22% of DHPs in IL and 5% in GE. Of the DHPs who used probes, 49% used metal probes in IL, while 40% used plastic probes in GE (p < 0.001). A majority of DHPs performed peri-implant instrumentation (IL: 168/99%; GE: 190/92%). Most DHPs from IL did not use devices other than hand and/or sonic/ultrasonic instruments for peri-implant cleaning (IL: 130/77%; GE 5/2%); in GE, the use of airflow (IL: 31/18%; GE: 199/96%) is popular (p < 0.001). Most DHPs in IL and GE perform peri-implant probing and debridement. However, there are some distinct differences between the two countries regarding the choice of instruments and treatment regimens.

Highly basic and active ZnO–x% K2O nanocomposite catalysts for the production of methyl ethyl ketone biofuel

AbstractHerein we demonstrate the preparation and characterization of nanocrystalline ZnO, either pure or promoted with 1–10 wt.% K2O. All catalysts calcined at 400°C were in the nano‐crystallite scale as confirmed by X‐ray powder diffraction analysis in the 22.9–28.0 nm range. According to the CO2‐temperature‐programmed desorption study using thermogravimetric analysis and differential scanning calorimetry techniques, they have a broad spectrum of surface basic sites. Because of the significance of methyl ethyl ketone (MEK) as a next‐generation biofuel candidate with high‐octane, low boiling point, and relatively high vapor pressure. The prepared catalysts were examined during the direct production of MEK via 2‐butanol (2B) dehydrogenation. Among catalysts tested, ZnO promoted with 1% K2O showed a superior catalytic activity towards the conversion of 2B to MEK, that is, 71.7% at a reaction temperature of 275°C. The selectivity for the production of MEK over all catalysts was ≥95% across all catalysts when using N2‐gas as a carrier. The use of airflow in this reaction resulted in a clear loss of selectivity toward MEK production as well as the appearance of undesirable products such as acetone and methanol. All catalytic properties of catalysts, particularly those of moderate strength, were highly correlated with the distribution of surface basic sites. Finally, a reaction mechanism was proposed for the dehydrogenation of 2B, followed by the partial oxidation of MEK.

Airflow for initial nonsurgical treatment of peri-implantitis: A systematic review and meta-analysis.

Nonsurgical treatment of peri-implantitis may help in reducing microbial load and inflammatory parameters. The potential clinical benefits of using different treatment approaches, in the initial nonsurgical treatment phase, particularly the airflow, are still not clear. The aim of this systematic review and meta-analyses was to evaluate the outcomes of nonsurgical treatment of peri-implantitis using airflow method in terms of changes in periodontal parameters, peri-implant marginal bone level, postoperative pain/discomfort, and patient satisfaction. Electronic databases were searched to identify randomized controlled trials (RCTs) that compared airflow with mechanical debridement using ultrasonic/curettes. The risk of bias was assessed using the Cochrane Collaboration's Risk of Bias tool. Data were analyzed using a statistical software program. A total of 316 studies were identified, of which, five RCTs with 288 dental implants in 174 participants were included. Overall meta-analysis showed more reduction in probing pocket depths at 1-3 months (mean difference [MD] -0.23; 95% confidence interval [CI] -0.50-0.05; p=0.10) and 6 months (MD -0.04; 95% CI -0.34 to 0.27; p=0.80) in favor of airflow, but the difference was not statistically significant. The use of airflow was associated with significant reduction in bleeding on probing and increase in peri-implant mucosal recession. The differences in plaque score, peri-implant marginal bone level changes, and patient reported outcomes between airflow and mechanical debridement were not statistically significant. The short-term clinical and radiographic outcomes following nonsurgical treatment of peri-implantitis using airflow or mechanical debridement were comparable. The airflow has short-term positive effects on reducing bleeding on probing. Further evidence from RCTs are still required to substantiate the current findings.

Composite surface roughness and color change following airflow usage

BackgroundEsthetic dental restorations have gained increasing popularity. The surface of restorations should be smooth enough to achieve maximum esthetics and prevent the adhesion of microorganisms and food particles. This study aimed to assess the surface roughness and color change of composite specimens following airflow usage.MethodsIn this in vitro, experimental study, 30 Tokuyama composite discs were fabricated and randomly divided into three groups (n = 10) for the use of airflow with calcium carbonate/bicarbonate powder and conventional polishing with FlexiDisc. The surface roughness of the specimens was measured by profilometry while the color change was assessed by measuring the L*, a* and b* color parameters using spectrophotometry before polishing (T1). The composite specimens were then polished for stain removal, and their surface roughness as well as color parameters were remeasured after polishing (T2). Paired t-test and Tukey’s test were applied for within-group and between-group comparisons.ResultsSignificant differences were noted in roughness average (Ra) between airflow with calcium carbonate (0.251 ± 0.014 μm) and airflow with sodium bicarbonate (0.421 ± 0.208 μm), and between airflow with sodium bicarbonate and FlexiDisc (0.207 ± 0.076 μm) groups after polishing (P < 0.05). Regarding the correlation of change in surface roughness and color parameters at T1 and T2, an inverse correlation was noted between the change in surface roughness and all color parameters except for L*. In other words, reduction in surface roughness decreased the a* and b* color parameters.ConclusionsWithin the limitations of this study, the results showed that the airflow device used in this study had no significant difference with conventional polishing in terms of reduction in surface roughness and staining. Considering the cost and maintenance of the airflow device, it is not suggested as a suitable alternative to the conventional polishing procedures.Trial Registration Number: This study does not involve human subjects.

Prospects for Improving the Technology of Post-harvest Grain and Seed Processing and Technical Means to Implement it

The paper presents the data of long-term research on the composition of harvested mass coming for post-harvest processing from grain harvesters, outlines possible ways to improve the technology of postharvest grain and seed processing. It proposes a number of engineering solutions and describes grain separators for sorting and grading all types of grain. A secondary aspiration channel with a double grain cleaning capacity and an installed pendulum valve was developed, providing high-quality cleaning of grain heaps in all types of processing and increases the sorting of biologically defective grain up to 20 %. Some solutions are proposed to reduce air and energy consumption by 20–30 % by mounting a sieve boot onto a corrugated elastic pneumatic cylinder and sequential use of air flow in a fractional separator for secondary cleaning of seeds, as well as a fundamentally new scheme of machines servicing air.

Design of an integrated cooling system by means of thermal variation flows

This project focuses on climate and to be more specific in high temperatures evidenced in some departments of Colombia. At present, the most widely used means of transport are motorcycles which must be supervised under a legal rule, taking into account their safety; therefore, it is necessary to use a certified helmet that fulfils the function of protecting this individual; these helmets in addition to having a definite shape and structure where it surrounds the skull completely in the part of the head also allows the option of having the chin protected or discovered depending on the speed at which the motorcycle is already established factory. Helmets normally have a system that aims not to allow internal heating of this for the convenience of the user, it consists of holes that allow the air flow that occurs when the driver is in motion to be transported throughout the hull and thereby cool it down gradually when driving, however, it does not fully serve its purpose as the distribution is not uniform and there are locations in the hull where this heat is concentrated, thus presenting a high temperature within the hull that makes the driver uncomfortable, taking into account the place and climate in which it is located. This study proposes a portable cooling system for motorcycle helmet that allows whoever is the carrier a state of comfort when driving your vehicle making your helmet stay cool despite the weather and temperatures that have naturally on the site of circulation, All this with the implementation of peltier cells and the use of air flow at the time of driving.

Seed distribution by the coulter for the subsoil broadcast seeding

The article studies the efficiency of the subsoil broadcast seeding of grain crops, which differs from other methods with the way seeds are placed into the soil: not in rows but on the whole distributing width. This method is also determined by the evenness of seeding depth by placing the seeds on the ready hard spot, which provides equal conditions of heat, light, water, food and gas supply that influence seed sprouting, seedling formation, tillering, shooting, head formation, earing, blossoming, kernel milk line formation, middle dough and fully ripe stage development. The analysis of coulter with active and passive distributors has been conducted. The use of air flow during the transportation of seeds from the sowing device to the coulter and the distributor oscillating process is recommended for the higher quality seed distribution below the spinning wheel. The oscillations of the elastic tube – distributor under the influence of the air-grain mixture have been theoretically studied. The obtained results allow creating dependency diagrams of oscillation frequency ω and damping parameter h. The experimental research has been made to study the evenness of seed distribution with the help of the coulter with the elastic tube – distributor.

Analytical studies of the technological parameters of the curved channel of the pneumatic separator

Purpose. Establishment of the laws governing the movement of particles in the air flow with an uneven distribution of flow velocity and the action of additional forces arising from this. Methods. Theoretical studies are based on the basic principles of theoretical mechanics, in particular dynamics, as well as the theory of differential equations of the first and second order Results. A mathematical description is obtained of the movement of particles of the grain mixture in the chamber of a gravity-air separator during the action of air flows of variable speed, as well as the trajectory of particles with different sizes. With certain assumptions, the obtained patterns of change in the velocity of a material particle (point) from coordinates. Conclusions 1.Based on theoretical studies, taking into account deflecting forces, the possibility of separating particles of grain material into fractions by aerodynamic properties in vertical channels and with a lower discharge is determined. 2.The use of air flow as a separating carrier can significantly increase the value of the splitting of the trajectories and the criterion for the separation of grain into fractions. 3.Created simplified mathematical models of the movement of the components of the grain material in air separators with vertical channels, which allow us to determine the rational modes of operation of new technical means. Keywords: air flow, variable air speed, trajectory, stability of forces, fractions, fractionation process, grain mixture, air separator, pneumatic circular flow.

ТЕОРЕТИЧЕСКОЕ ИССЛЕДОВАНИЕ УСТОЙЧИВОСТИ ЭЛАСТИЧНОЙ ТРУБКИ-РАССЕВАТЕЛЯ

The use of subsoil-scattered seeding of cereal crops allows to achieve seed distribution on the packed bed along the entire width of the seeding machine. With this seeding method, the seeds are evenly distributed relative to each other, which creates the same conditions for nutrition and plant growth. In order to obtain a better distribution of seeds in the podlag space, the use of air flow is suggested when transporting seeds from the seeder to the opener and the oscillatory process of the distributor. The flow of the air-grain flow from the cantilevered suspension elastic tube causes the action of longitudinal compressive forces, the directions of which coincide with the tangent to the axis at the end of the tube, that is, the so-called “tracking” force arises. The deviations of an elastic scattering pipe under conditions of relatively small and large deviations from the axis of the pipe are considered. This approach of theoretical research allows us to judge the correctness of the selected models by agreeing on the results obtained. Based on the results of the study, analytical expressions were obtained that allow us to determine the coordinates of the location of the deflected tube as a function of the speed of the air-grain flow for a qualitative distribution of seeds in the sublobe space, the critical value of the tube deflection angle equal to θ = 1.173 rad, which corresponds to the coefficient of friction of the medium fm = 0 , 2.

“Prologues to a Bad Voice”: Effect of Vocal Hygiene Knowledge and Training on Voice Quality Following Stage Performance

The purpose of this investigation was to determine the effects of intensive stage rehearsal and performance on perceptual, acoustic, and aerodynamic measures of voice, and to determine the impact of knowledge and practice of vocal hygiene on measures of voice during intensive vocal performance. Nineteen stage actors who were participating in the Arkansas Shakespeare Theatre festival took part in the study. Each participant completed auditory-perceptual, acoustic, aerodynamic, and quality of life measures before and after 1 month of intensive rehearsals and stage performances. They also completed a questionnaire documenting their vocal use, vocal hygiene, and previous vocal training, if any. Subjects demonstrated statistically significant deterioration in auditory-perceptual measures and mean expiratory airflow. Other acoustic measures trended toward poorer outcomes after the performances; however, these were not statistically significant. Knowledge of vocal hygiene and vocal training did not have an impact on the change in vocal measures. Stage performances do impact vocal outcomes with reduction in quality and efficient use of airflow for voice production. Knowledge and practice of vocal hygiene have some impact on these changes; however, vocal hygiene may not be the best preventive strategy of potential phonotrauma in this subject population.

Подготовка высококачественных семян с использованием пневмосепараторов

In preparing of seed material it is important not only to compliance with the requirements of GOST R 52325-2005 for seed quality, content of seeds of other species, impurities, germination, but also the selection adjusted, the most biologically high-grade fractions. The use of airflow is one of the most common and effective ways to clean seeds from impurities. Separation of seeds by airflow allows to allocate the seeds with higher germination ability compared to separation on sieves. In Federal State Budgetary Scientific Institution "NIISH Severo-Vostoka" the effect of separation seeds of naked oat by airflow on yield quality and crop capacity was studied. Seeds were separated into heavy, medium and light fractions in two passes by the separator SP-4U-P. Grain yield in average in 2008-2010 at sowing seeds of light fraction was lower than control by 0.1-0.2 t/ha. When sowing seeds of heavy and medium fractions grain yield increased compared to control near equal - by 0.2-0.3 t/ha. Thus it is noted good sprouts, and tillering plants three days earlier. In order to reduce the discounted costs of cleaning the seeds pneumatic separator SP-2F was developed which one devides seeds on I-st and II-nd grade, grain forage and waste in a single pass. Evaluation of the quality of work of the separator carried at cleaning of covered oat Sapsan with base values: content of seeds of the main crop 97.04%, crushed grain 0.15%, husked grains 0.18%, small and feeble grain 2.47%, seeds of other species 6 pcs./kg, 1000 seeds weight 41.28 g. After pneumo-separation purity and germination of the I-st grade seeds rose to values met category OS, II grade - up to category РС with acceptable losses in the waste. Isolation of heavy and medium seed fractions with use of pneumatic separators increases yield quality and crop capacity. Application of pneumatic separator SP-2F allows to get the I and II grade seeds in one pass, and reduce the discounted costs.

Design features of fan assembly in automobiles

Nowadays in the engine cooling system and in air-conditioning system of passenger compartment and cabin of tractor is applied a great variety of designs of fan units for the supply of cooling air. A distinctive feature of fan units of automobiles is that they need not only to supply cooling air, but also must make efficient use of air flow. This is not an easy task, because these two functions are almost always in conflict. The problem becomes even more complicated when a car air conditioner is installed. Efficiency factor of the incident flow is higher than the efficiency of the fan. It is therefore necessary to use more efficient the incoming air flow. The article analyzes the most common fan assemblies of automobiles used for the operation of the engine cooling and passenger compartment air conditioning system. Its strengths and weaknesses were evaluated. There were evaluated the most important characteristics: the effectiveness of the fan use, the rational use of air flow when the vehicle is moving, mass-dimensional characteristics and the noise produced by the fans in their work. The conclusions and recommendations for improving the fan installations were given. When choosing one or another variant of the fan assembly it is needed to take into account the features of the automobile design. High efficiency of fan can be obtained when the fan shroud has a full coverage of the radiator. In this case, for rational use of incoming flow is necessary to install in the fan cover the valves of a large cross-section in contrast to traditional, these valves must be driven to forced opening and closing.

Inflatable plastic solar still with passive condenser for single family use

Plastics have been the preferred choice of material for the commercial production of the solar stills. However, most of the currently available solar stills are either too big or too small for satisfying drinking water needs of a single family. Furthermore, methods for increasing the production of water from a solar still are often difficult and costly to integrate in a solar still. Here, we show the effect of adding a plastic channels as passive condenser on an inflatable solar still. The still has a basin area of 1.8m2. The tests were performed in lab conditions at different water temperatures. The production of water achieved from the still at a water temperature of 73 ° C was 0.75 l/h. Furthermore, the production of water increased to more than 0.95 l/h with use of air flow over the the passive condenser to mimic wind or with use of wet tissue on the passive condenser to mimic evaporation cooling.

Minimum Outdoor Air Control and Building Pressurization with Lack of Airflow and Pressure Sensors in Air-Handling Units

AbstractIdeally, minimum outdoor air and building static pressures are controlled through feedback controllers with the use of airflow and pressure sensors in air-handling units (AHUs). Unfortunately, because these sensors are not always installed in AHUs, it is common to maintain the minimum outdoor airflow by fixing the AHU control dampers at minimum positions and maintain the building static pressure by tracking the return fan speed with the supply fan speed. The purpose of this paper is to evaluate the system performance of these alternative controls. The outdoor airflow and building static pressure of an AHU is simulated using a nonlinear network solution. The simulation results show that the fixed damper position method can approximately maintain a constant outdoor airflow ratio with an appropriate damper connection if the building static pressure is perfectly controlled. The return fan speed linear tracking method along with the fixed damper position method shows performance in maintaining the mini...

Airflow assisted printhead for high-resolution electrohydrodynamic jet printing onto non-conductive and tilted surfaces

Electrohydrodynamic jet printing (e-jet printing) is a growing high resolution (&amp;lt;20 μm) printing technology. It is cost effective for small scale and highly customized feature production and it is compatible with a large range of materials. Conventional e-jet is generally restricted to surfaces with high flatness, therefore limiting the application of e-jet in research and industry. This paper will present an airflow assisted e-jet printhead that incorporates the use of airflow within the printhead to direct electrohydrodynamically generated ink droplets onto non-conductive and tilted surfaces. The printhead runs in open loop yet achieves consistent printing performance across large changes in standoff height (800 μm) between the printhead and printing surface. The printhead is able to print &amp;lt;20 μm droplets, which surpasses traditional inkjet technology. In conclusion, this printhead design has the potential to enable e-jet printing to be applied in unprecedented application areas.

Use of airflow to improve the nanofibrous structure and quality of nanofibers from needleless electrospinning

Mass production of nanofibers from needleless electrospinning shows great potential in research and development of nanofibers. However, how to improve the electrospinning performance so as to achieve high quality nanofibers is still of great challenge. In this study, airflow has been applied to optimize upward needleless electrospinning from ring spinneret. Effects of airflow speed and the position of airflow on the nanofiber quality and production rate have been investigated. It has been found that thinner and more uniform nanofibers were produced when airflow was applied to needleless electrospinning system. It also improved the collected nonwoven membrane, resulting in better nanofibrous structure of the as-spun nanofibers. Application of airflow on needleless electrospinning would further benefit the development of mass production of nanofibers from needleless electrospinning.