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1
Mota, Alisson A. B., Ulisses R. Antuniassi, Rodolfo G. Chechetto, Rone B. de Oliveira, and Anne C. A. e. Silva. "Effect of adjuvants on the amount of air included in droplets generated by spray nozzles." Engenharia Agrícola 33, no. 6 (December 2013): 1281–88. http://dx.doi.org/10.1590/s0100-69162013000600020.
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The air included in droplets generated by spray nozzles directly int0erferes in transport, deposition and retention of the droplets after its impact on the target. The objective of this study was to analyze the interference of adjuvants in the amount of air included in droplets generated by spray nozzles. The treatments were composed by four spray solutions containing mineral oil, vegetable oil, surfactant and water, and three spray nozzles, two air induction type and one pre-orifice. The air included was calculated by the difference between the volume of spray mix (air plus liquid) and only the liquid, which was made by means of sprayed samples captured in a funnel and collected in a graduated cylinder. The surface tension was estimated by the gravimetric method using a precision scale and a graduated pipette. The surfactant provided the largest percentage of air included in the spray. For the surface tension, the mineral oil and the surfactant had the lowest values. It was concluded that the use of adjuvants had a direct influence on the percentage of air included. In addition, products with greater ability to reduce surface tension and to form homogeneous solutions provided the increase in the percentage of air included in the droplet.
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Shinjo, J., J. Xia, L. C. Ganippa, and A. Megaritis. "Puffing-enhanced fuel/air mixing of an evaporating -decane/ethanol emulsion droplet and a droplet group under convective heating." Journal of Fluid Mechanics 793 (March 18, 2016): 444–76. http://dx.doi.org/10.1017/jfm.2016.130.
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Puffing of a decane/ethanol emulsion droplet and a droplet group under convective heating and its effects on fuel/air mixing are investigated by direct numerical simulation that resolves all of the liquid/gas and liquid/liquid interfaces. With distinct differences in the boiling point between decane and ethanol, the embedded ethanol sub-droplets can be superheated and boil explosively. Puffing, i.e. ejection of ethanol vapour, occurs from inside the parent decane droplet, causing secondary breakup of the droplet. The ejected ethanol vapour mixes with the outer gas mixture composed of air and vapour of the primary fuel decane, and its effects on fuel/air mixing can be characterised by the scalar dissipation rates (SDRs). For the primary-fuel SDR, the cross-scalar diffusion due to ethanol vapour puffing plays a dominant role in enhancing the micromixing. When the vapour ejection direction is inclined towards the wake direction, the wake is elongated, but the shape of the stoichiometric mixture fraction isosurface is not changed much, indicating a limited effect on droplet grouping in a spray. On the other hand, when the ejection direction is inclined towards the transverse direction, the stoichiometric surface is pushed further away in the transverse direction, and its topology is changed by the puffing. The trajectories of ejected ethanol vapour pockets can be predicted by the correlation obtained for a jet in cross-flow, and the vapour pockets may reach a few diameters away from the droplet. Therefore, in a multiple-droplet configuration, the transverse ethanol vapour ejection due to puffing may transiently change the droplet grouping characteristics. In simulation cases with multiple droplets, the interaction changing the droplet grouping due to puffing has been confirmed, especially for droplets in the most upstream position in a spray. This implies that puffing should be accurately included in the mixing and combustion modelling of such a biofuel-blended diesel spray process.
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Yasuda, Naohiro, Koji Yamamura, and Yasuhiko H. Mori. "Impingement of liquid jets at atmospheric and elevated pressures: an observational study using paired water jets or water and methylcyclohexane jets." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 466, no. 2124 (June 9, 2010): 3501–26. http://dx.doi.org/10.1098/rspa.2010.0144.
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We have observed the impingement of two cylindrical liquid jets of either the same liquid, water, or two mutually immiscible liquids, water and methylcyclohexane (MCH), in either air under normal pressure (0.101 MPa) or nitrogen gas under elevated pressures up to 4.0 MPa. The flow rates of the two jets were adjusted such that they had equal axial momentum. Irrespective of the system pressure, we distinguished two characteristic regimes: the lower flow-rate regime, in which the jet impingement formed a regularly shaped planar sheet, and a higher flow-rate regime, in which a wrinkled sheet repeated azimuthal breakup. The transition from the former to the latter regime occurred at a lower flow rate for the water–MCH impingement than for the water–water impingement. An increase in the system pressure tended to shrink the liquid sheets, to promote the transition to the sheet-breakup regime and to intensify the liquid atomization. The formation of water–MCH compound droplets by the water–MCH impingement was confirmed visually.
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Shibaev, P. V., M. Wenzlick, J. Murray, A. Tantillo, and J. Howard-Jennings. "Rebirth of Liquid Crystals for Sensoric Applications: Environmental and Gas Sensors." Advances in Condensed Matter Physics 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/729186.
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Films and droplets of liquid crystals may soon become an essential part of sensitive environmental sensors and detectors of volatile organic compounds (VOCs) in the air. In this paper a short overview of recent progress in the area of sensors based on liquid crystals is presented, along with the studies of low molar mass liquid crystals as gas sensors. The detection of VOCs in the air may rely on each of the following effects sequentially observed one after the other: (i) slight changes in orientation and order parameter of liquid crystal, (ii) formation of bubbles on the top of the liquid crystalline droplet, and (iii) complete isotropisation of the liquid crystal. These three stages can be easily monitored by a photo camera and/or optical microscopy. Detection limits corresponding to the first stage are typically lower by a factor of at least 3–6 than detection limits corresponding to isotropisation. The qualitative model taking into account the reorientation of liquid crystals is presented to account for the observed changes.
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Dupuy, R., P. Laj, and K. Sellegri. "Cn to ccn relationships and cloud microphysical properties in different air masses at a free tropospheric site." Atmospheric Chemistry and Physics Discussions 6, no. 1 (February 1, 2006): 879–98. http://dx.doi.org/10.5194/acpd-6-879-2006.
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Abstract. The fraction of aerosol particles activated to droplets (CCN) is often derived from semi-empirical relationships that commonly tend to overestimate droplet number concentration leading to major uncertainties in global climate models. One of the difficulties in relating aerosol concentration to cloud microphysics and cloud albedo lies in the necessity of working at a constant liquid water path (LWP), which is very difficult to control. In this study we observed the relationships between aerosol number concentration (NCN), cloud droplet concentration (Nd) and effective radius (Reff), at the Puy de Dôme (France). A total of 20 cloud events were sampled representing a period of more than 250 h of cloud sampling. Samples are classified first according to air mass origins (Modified Marine, Continental and Polluted) and then according to their liquid water content (Thin, Medium and Thick clouds). The CCN fraction of aerosols appears to vary significantly according to the air mass origin. It is maximum for Continental air masses and minimum for Polluted air masses. Surprisingly, the CCN fraction of Modified Marine air masses fraction is lower than the continental air mass and from expected from previous studies. The limited number of activated particles in Modified Marine air masses is most likely the result of the presence of hydrophobic organic compounds. The limited activation effect leads to a 0.5 to 1 μm increase in Reff with respect to an ideal Marine case. This is significant and implies that the dReff/dNCN of low-continental clouds is higher than expected.
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Kim, Jinhong, and Sung-Jin Park. "In-Situ Photo-Dissociation and Polymerization of Carbon Disulfide with Vacuum Ultraviolet Microplasma Flat Lamp for Organic Thin Films." Applied Sciences 11, no. 6 (March 15, 2021): 2597. http://dx.doi.org/10.3390/app11062597.
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Vacuum UV (VUV) photo-dissociation for a liquid phase organic compound, carbon disulfide (CS2), has been investigated. 172 nm (7.2 eV) VUV photons from Xe2* excimers in a microcavity plasma lamp irradiated free-standing liquid droplets on Si substrate in each a nitrogen environment and an atmospheric air environment. Selective and rapid dissociation of CS2 into C-C, C-S or C-O-S based fragments was observed in the different gas environments during the reaction. Thin-layered polymeric microdeposites have been identified by characterization with a Scanning electron microscope (SEM), Energy dispersive x-ray spectroscopy (EDX), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). This novel photo-process from the flat VUV microplasma lamp introduces another pathway of low-temperature organic (or synthetic) conversion for large area deposition. The in-situ, selective conversion of various organic precursors can be potentially used in optoelectronics and nanotechnology applications.
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Huang, Shuquan, Jessica Connolly, Andrei Khlystov, and Richard B. Fair. "Digital Microfluidics for the Detection of Selected Inorganic Ions in Aerosols." Sensors 20, no. 5 (February 27, 2020): 1281. http://dx.doi.org/10.3390/s20051281.
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A prototype aerosol detection system is presented that is designed to accurately and quickly measure the concentration of selected inorganic ions in the atmosphere. The aerosol detection system combines digital microfluidics technology, aerosol impaction and chemical detection integrated on the same chip. Target compounds are the major inorganic aerosol constituents: sulfate, nitrate and ammonium. The digital microfluidic system consists of top and bottom plates that sandwich a fluid layer. Nozzles for an inertial impactor are built into the top plate according to known, scaling principles. The deposited air particles are densely concentrated in well-defined deposits on the bottom plate containing droplet actuation electrodes of the chip in fixed areas. The aerosol collection efficiency for particles larger than 100 nm in diameter was higher than 95%. After a collection phase, deposits are dissolved into a scanning droplet. Due to a sub-microliter droplet size, the obtained extract is highly concentrated. Droplets then pass through an air/oil interface on chip for colorimetric analysis by spectrophotometry using optical fibers placed between the two plates of the chip. To create a standard curve for each analyte, six different concentrations of liquid standards were chosen for each assay and dispensed from on-chip reservoirs. The droplet mixing was completed in a few seconds and the final droplet was transported to the detection position as soon as the mixing was finished. Limits of detection (LOD) in the final droplet were determined to be 11 ppm for sulfate and 0.26 ppm for ammonium. For nitrate, it was impossible to get stable measurements. The LOD of the on-chip measurements for sulfate was close to that obtained by an off-chip method using a Tecan spectrometer. LOD of the on-chip method for ammonium was about five times larger than what was obtained with the off-chip method. For the current impactor collection air flow (1 L/min) and 1 h collection time, the converted LODs in air were: 0.275 μg/m3 for sulfate, 6.5 ng/m3 for ammonium, sufficient for most ambient air monitoring applications.
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Zamora, Rosendo, Juan Martínez-Pastor, and Félix Faura. "Thermal, Viscoelastic and Surface Properties of Oxidized Field’s Metal for Additive Microfabrication." Materials 14, no. 23 (December 2, 2021): 7392. http://dx.doi.org/10.3390/ma14237392.
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Field’s metal, a low-melting-point eutectic alloy composed of 51% In, 32.5 Bi% and 16.5% Sn by weight and with a melting temperature of 333 K, is widely used as liquid metal coolant in advanced nuclear reactors and in electro–magneto–hydrodynamic two-phase flow loops. However, its rheological and wetting properties in liquid state make this metal suitable for the formation of droplets and other structures for application in microfabrication. As with other low-melting-point metal alloys, in the presence of air, Field’s metal has an oxide film on its surface, which provides a degree of malleability and stability. In this paper, the viscoelastic properties of Field’s metal oxide skin were studied in a parallel-plate rheometer, while surface tension and solidification and contact angles were determined using drop shape analysis techniques.
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Simon, Julianna C., Oleg A. Sapozhnikov, Vera A. Khokhlova, Lawrence A. Crum, and Michael R. Bailey. "Ultrasonic atomization of liquids in drop-chain acoustic fountains." Journal of Fluid Mechanics 766 (February 2, 2015): 129–46. http://dx.doi.org/10.1017/jfm.2015.11.
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AbstractWhen focused ultrasound waves of moderate intensity in liquid encounter an air interface, a chain of drops emerges from the liquid surface to form what is known as a drop-chain fountain. Atomization, or the emission of micro-droplets, occurs when the acoustic intensity exceeds a liquid-dependent threshold. While the cavitation-wave hypothesis, which states that atomization arises from a combination of capillary-wave instabilities and cavitation bubble oscillations, is currently the most accepted theory of atomization, more data on the roles of cavitation, capillary waves, and even heat deposition or boiling would be valuable. In this paper, we experimentally test whether bubbles are a significant mechanism of atomization in drop-chain fountains. High-speed photography was used to observe the formation and atomization of drop-chain fountains composed of water and other liquids. For a range of ultrasonic frequencies and liquid sound speeds, it was found that the drop diameters approximately equalled the ultrasonic wavelengths. When water was exchanged for other liquids, it was observed that the atomization threshold increased with shear viscosity. Upon heating water, it was found that the time to commence atomization decreased with increasing temperature. Finally, water was atomized in an overpressure chamber where it was found that atomization was significantly diminished when the static pressure was increased. These results indicate that bubbles, generated by either acoustic cavitation or boiling, contribute significantly to atomization in the drop-chain fountain.
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Zhao, Ning-Ning, Xin-Yu Xiao, Feng-Xian Fan, and Ming-Xu Su. "Ultrasonic attenuation model of mixed particle three-phase system based on Monte Carlo method." Acta Physica Sinica 71, no. 7 (2022): 074303. http://dx.doi.org/10.7498/aps.71.20211869.
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From the perspective of calculating ultrasonic absorption and scattering properties of individual solid particle and droplet, the ultrasonic wave is treated as discrete phonons. And by tracking their motion process and event statistics, a new prediction model of ultrasonic attenuation of spherical mixed particles in gaseous medium is established with Monte Carlo method. Considering the difference in physical properties between solid particles and liquid particles, the ultrasonic absorption characteristics of the two kinds of particles are obviously different, and when dimensionless particle size <i>kR</i> ≤ 1, the backscattering of particles is uniform and dominant, then the ultrasonic scattering pressures gradually transit from the dominant position of backscattering to the trend of forward enhancement with the increase of dimensionless particle size. The numerical simulation results for the system with a single particle type are compared with those from various standard models such as classical ECAH model and McC model, showing that they are in good agreement. Similarly, the results are then compared with experimental results, which accord with each other in general. After calculating and verifying the ultrasonic attenuation of aluminum particles and submicron droplets respectively in air, the method is extended to the three-phase monodisperse and polydisperse mixed particle system composed of aluminum particles and liquid droplets. In the three-phase system of gas-liquid-solid mixed particles, the particle type has a significant influence on ultrasonic attenuation, and the attenuation contribution of different particles against mixing ratio does not follow the linear gradient with the increase of volume concentration. For a polydisperse system, the ultrasonic attenuation spectrum is greatly affected by the average particle size, but it is insensitive to the width of particle size distribution. The numerical results also show that both the particle type and particle distribution size should be carefully take into account in the polydisperse system. Moreover, the MCM model can be further extended to non-spherical particles and combined with mathematical inversion to form the theoretical basis for the measurement of mixed particle system.
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Shantz, N. C., R. Y. W. Chang, J. G. Slowik, J. P. D. Abbatt, and W. R. Leaitch. "Slower CCN growth kinetics of anthropogenic aerosol compared to biogenic aerosol observed at a rural site." Atmospheric Chemistry and Physics Discussions 9, no. 3 (June 23, 2009): 13775–99. http://dx.doi.org/10.5194/acpd-9-13775-2009.
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Abstract. Growth rates of water droplets were measured with a static diffusion cloud condensation chamber in May–June 2007 at a rural field site in Southern Ontario, Canada, 70 km north of Toronto. Observations were made during periods when the winds were from the south and the site was impacted by anthropogenic air from the US and Southern Ontario as well as during a 5-day period of northerly wind flow when the aerosol was dominated by biogenic sources. The growth of droplets on anthropogenic size-selected particles centred at 0.1 μm diameter and composed of approximately 40% organic and 60% ammonium sulphate (AS) by mass, was delayed on the order of 1 second compared to a pure AS aerosol. Simulations of the growth rate indicate that a lowering of the water mass accommodation coefficient from αc=1 to an average of αc=0.044 is needed (assuming an insoluble organic with hygroscopicity parameter, κorg, of zero). In contrast, the growth rate of the aerosol of biogenic character, consisting of >80% organic, was similar to that of pure AS. Simulations of the predominantly biogenic aerosol show agreement between the observations and simulations when κorg=0.05–0.2 and αc=1. Inhibition of water uptake by the anthropogenic organic applied to an adiabatic cloud parcel model in the form of a constant low αc increases the number of droplets in a cloud compared to pure AS. If the αc is assumed to increase with increasing liquid water on the droplets, then the number of droplets decreases which could diminish the indirect effect. The slightly lower κorg in the biogenic case decreases the number of droplets in a cloud compared to pure AS.
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Veeramanikandasamy*, T., Gokul Raj. S, A. Balamurugan, A. P. Ramesh, and Y. A. Syed Khadar. "IoT based Real-time Air Quality Monitoring and Control System to Improve the Health and Safety of Industrial Workers." International Journal of Innovative Technology and Exploring Engineering 9, no. 4 (February 28, 2020): 1889–84. http://dx.doi.org/10.35940/ijrte.d1604.018520.
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Pollution is adding contaminants into the nature that causes an adverse change in the environment. Air pollution is one of the highest mortality risk factors globally. The sources of air pollution in the industries are power plants, chamber process, cleaning, burning of materials, etc. A variety of pollutants emitted into the air such as sulfur dioxide, carbon monoxide, carbon dioxide, ammonia and volatile organic compounds. Particulate Matter (PM) is an air pollutant that is the mixture of solid dust or pollen and liquid droplets with air. Air pollution in industrial workplaces is a major concern and monitoring and management of it to be addressed to protect the industrial workers health from the air pollution effects. The people are suffering from several respiratory and heart issues along with cancer due to increasing air pollution. This device is composed of ESP32 MCU, MQ135 gas sensor, SDS011 optical dust particle sensor, and BME280 humidity and temperature sensor for monitoring the air quality. The gas sensor MQ135 senses the harmful gases present in the environment. SDS011 optical dust sensor senses the PM levels (PM10 and PM2.5) in the atmosphere. The sensor values are evaluated for the Air Quality Index (AQI) and display it on the ThingSpeak IoT platform. Vrituino app has used for a virtual screen with widgets on the mobile phone to monitor the system using the web. In order to improve the real-time performance of the system, an IoT and a cloud computing technology are being used. The ESP32 turns on the fan units to maintain the pollutants within the safe limit when the presence of harmful gases and PM levels exceeds a certain threshold level. This system is essential for industrial work places to adopt measures and control air pollution which increase industrial workers safety.
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Shantz, N. C., R. Y. W. Chang, J. G. Slowik, A. Vlasenko, J. P. D. Abbatt, and W. R. Leaitch. "Slower CCN growth kinetics of anthropogenic aerosol compared to biogenic aerosol observed at a rural site." Atmospheric Chemistry and Physics 10, no. 1 (January 15, 2010): 299–312. http://dx.doi.org/10.5194/acp-10-299-2010.
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Abstract. Growth rates of water droplets were measured with a static diffusion cloud condensation chamber in May–June 2007 at a rural field site in Southern Ontario, Canada, 70 km north of Toronto. The observations include periods when the winds were from the south and the site was impacted by anthropogenic air from the U.S. and Southern Ontario as well as during a 5-day period of northerly wind flow when the aerosol was dominated by biogenic sources. The growth of droplets on anthropogenic size-selected particles centred at 0.1 μm diameter and composed of approximately 40% organic and 60% ammonium sulphate (AS) by mass, was delayed by on the order of 1 s compared to a pure AS aerosol. Simulations of the growth rate on monodisperse particles indicate that a lowering of the water mass accommodation coefficient from αc=1 to an average of αc=0.04 is needed (assuming an insoluble organic with hygroscopicity parameter, κorg, of zero). Simulations of the initial growth rate on polydisperse anthropogenic particles agree best with observations for αc=0.07. In contrast, the growth rate of droplets on size-selected aerosol of biogenic character, consisting of >80% organic, was similar to that of pure AS. Simulations of the predominantly biogenic polydisperse aerosol show agreement between the observations and simulations when κorg=0.2 (with upper and lower limits of 0.5 and 0.07, respectively) and αc=1. Inhibition of water uptake by the anthropogenic organic applied to an adiabatic cloud parcel model in the form of a constant low αc increases the number of droplets in a cloud compared to pure AS. If the αc is assumed to increase with increasing liquid water on the droplets, then the number of droplets decreases which could diminish the indirect climate forcing effect. The slightly lower κorg in the biogenic case decreases the number of droplets in a cloud compared to pure AS.
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Lu, Shanshuai, Congling Li, Rui Liu, and Aifeng Lv. "PVP-Assisted Shellac Nanofiber Membrane as Highly Efficient, Eco-Friendly, Translucent Air Filter." Applied Sciences 11, no. 23 (November 23, 2021): 11094. http://dx.doi.org/10.3390/app112311094.
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Particulate matter (PM), composed of tiny solids and liquid droplets in polluted air, poses a serious threat to human health. Traditional air filters usually cause secondary pollution due to their poor degradability. Here, shellac, as an environmentally friendly natural organic material, was successfully applied to fabricate biodegradable air filters. Since pure shellac fiber shows poor mechanical properties and bad light transmittance, we then introduced a small amount of polyvinylpyrrolidone (PVP) in the shellac solution to prepare highly efficient air filter membranes by the electrospinning method. The prepared PVP-assisted shellac nanofiber membrane (P-Shellac FME) demonstrated improved filtration efficiencies as high as 95% and 98% for PM2.5 and PM10, respectively. The P-Shellac FME also showed good stability, with filtration efficiencies still above 90% and 95% for PM2.5 and PM10 even after six hours of air filtering under high PM concentrations. The pressure drop going through the filter was only 101 Pa, which is also comparable to the value of 76 Pa obtained using commercial polypropylene nanofibers (PP nanofibers, peeled off from the surgical mask), indicating good air permeability of P-Shellac FME. Additionally, P-Shellac FME also showed the advantages of translucence, biodegradability, improved mechanical properties, and low cost. We believe that the P-Shellac FME will make a significant contribution in the application of air filtration.
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Matsubara, Hiroki, Rikako Mori, and Eisuke Ohtomi. "Nucleation of Surfactant–Alkane Mixed Solid Monolayer and Bilayer Domains at the Air–Water Interface." Materials 15, no. 2 (January 9, 2022): 485. http://dx.doi.org/10.3390/ma15020485.
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We investigated the wetting transitions of tetradecane and hexadecane droplets in dodecyltrimethylammonium bromide (C12TAB), tetradecyltrimethylammonium bromide (C14TAB), and hexadecyltrimethylammonium bromide (C16TAB) aqueous solutions. By varying the surfactant concentration, the formation of mixed monolayers of a surfactant and an alkane was observed at the air–water interface. Depending on the combination of surfactant and alkane, these wetting monolayers underwent another thermal phase transition upon cooling either to a frozen mixed monolayer (S1) or a bilayer structure composed of a solid monolayer of a pure alkane rested on a liquid-like mixed monolayer (S2). Based on the phase diagrams determined by phase modulation ellipsometry, the difference in the morphology of the nucleated S1 and S2 phase domains was also investigated using Brewster angle microscopy. Domains of the S1 phase were relatively small and highly branched, whereas those of the S2 phase were large and circular. The difference in domain morphology was explained by the competition of the domain line tension and electrostatic dipole interactions between surfactant molecules in the domains.
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Zhang, Ling, Changjin Ou, Dhammika Magana-Arachchi, Meththika Vithanage, Kanth Swaroop Vanka, Thava Palanisami, Kanaji Masakorala, et al. "Indoor Particulate Matter in Urban Households: Sources, Pathways, Characteristics, Health Effects, and Exposure Mitigation." International Journal of Environmental Research and Public Health 18, no. 21 (October 21, 2021): 11055. http://dx.doi.org/10.3390/ijerph182111055.
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Particulate matter (PM) is a complex mixture of solid particles and liquid droplets suspended in the air with varying size, shape, and chemical composition which intensifies significant concern due to severe health effects. Based on the well-established human health effects of outdoor PM, health-based standards for outdoor air have been promoted (e.g., the National Ambient Air Quality Standards formulated by the U.S.). Due to the exchange of indoor and outdoor air, the chemical composition of indoor particulate matter is related to the sources and components of outdoor PM. However, PM in the indoor environment has the potential to exceed outdoor PM levels. Indoor PM includes particles of outdoor origin that drift indoors and particles that originate from indoor activities, which include cooking, fireplaces, smoking, fuel combustion for heating, human activities, and burning incense. Indoor PM can be enriched with inorganic and organic contaminants, including toxic heavy metals and carcinogenic volatile organic compounds. As a potential health hazard, indoor exposure to PM has received increased attention in recent years because people spend most of their time indoors. In addition, as the quantity, quality, and scope of the research have expanded, it is necessary to conduct a systematic review of indoor PM. This review discusses the sources, pathways, characteristics, health effects, and exposure mitigation of indoor PM. Practical solutions and steps to reduce exposure to indoor PM are also discussed.
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Mitova, Maya I., Camille Cluse, Daniela Correia, Catherine G. Goujon-Ginglinger, Samuel Kleinhans, Laurent Poget, and Sandra S. Sendyk. "Comprehensive Air Quality Assessment of the Tobacco Heating System 2.2 under Simulated Indoor Environments." Atmosphere 12, no. 8 (July 31, 2021): 989. http://dx.doi.org/10.3390/atmos12080989.
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Despite the growing popularity of heated tobacco products, there are few comprehensive studies on their environmental aerosols. Therefore, the impact of the Tobacco Heating System 2.2 (THS 2.2) on indoor air quality was evaluated on the basis of a comprehensive list of 31 airborne constituents along with targeted screening of the gas–vapor and particulate phases of the environmental aerosol. The assessments were conducted at three ventilation rates. Indoor use of THS 2.2 increased the levels of nicotine, acetaldehyde, glycerin, and (if mentholated products were used) menthol relative to background levels, with a corresponding increase in total volatile organic compounds (TVOC) values. Moreover, a temporary increase in ultrafine particles was observed when two or more tobacco sticks were used simultaneously or with a short time lapse between usages, but the concentrations returned to close to background levels almost immediately. This is because THS 2.2 generates an aerosol of liquid droplets, which evaporate quickly. Nicotine, acetaldehyde, glycerin, and TVOC levels were measured in the low μg/m3 range and were below the existing guideline limits. A comparison of airborne constituent levels during indoor THS 2.2 use with emissions from combustion products and common everyday activities revealed a substantially lower impact of THS 2.2 on the indoor environment.
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Nourian, Amir, Ghasem G. Nasr, Andrew J. Yule, Tom Goldberg, and Greig Tulloch. "Next generation of consumer aerosol valve design using inert gases." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, no. 16 (November 17, 2014): 2952–76. http://dx.doi.org/10.1177/0954406214559998.
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The current global consumer aerosol products such as deodorants, hairsprays, air-fresheners, polish, insecticide, disinfectant are primarily utilised unfriendly environmental propellant of liquefied petroleum gas (LPG) for over three decades. The advantages of the new innovative technology described in this paper are: (i) no butane or other liquefied hydrocarbon gas; (ii) compressed air, nitrogen or other safe gas propellant; (iii) customer acceptable spray quality and consistency during can lifetime; (iv) conventional cans and filling technology. Volatile organic compounds and greenhouse gases must be avoided but there are no flashing propellants replacements that would provide the good atomisation and spray reach. On the basis of the energy source for atomising, the only feasible source is inert gas (i.e. compressed air), which improves atomisation by gas bubbles and turbulence inside the atomiser insert of the actuator. This research concentrates on using ‘bubbly flow’ in the valve stem, with injection of compressed gas into the passing flow, thus also generating turbulence. Using a vapour phase tap in conventional aerosol valves allows the propellant gas into the liquid flow upstream of the valve. However, forcing bubbly flow through a valve is not ideal. The novel valves designed here, using compressed gas, thus achieved the following objectives when the correct combination of gas and liquid inlets to the valve, and the type and size of atomiser ‘insert’ were derived: Produced a consistent flow rate and drop size of spray throughout the life of the can, compatible with the current conventional aerosols that use LPG: a new ‘constancy’ parameter is defined and used to this end. Obtained a discharge flow rate suited to the product to be sprayed; typically between 0.4 g/s and 2.5 g/s. Attained the spray droplets size suited to the product to be sprayed; typically between 40 µm and 120 µm.
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Udoji Itodo, Adams, Sumi Roselyn Benjamin, and S. Ande. "Non Destructive Methods (XRF and XRD) For Estimation of Impure Carbon and Heavy Metals in Printer Toner Ink Powder." Academic Journal of Chemistry, no. 47 (July 15, 2018): 40–49. http://dx.doi.org/10.32861/ajc.47.40.49.
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Air pollution constitutes the largest among all of the environmental risks. Dust and soot fragments forms components of air particulates, which are released into the air as extremely small particles or liquid droplets. The basis of this research is to characterize toner ink powder and wood soot samples and the detection of metallic pollutants in wood soot (WS) and printer toner ink (PIS) for their physicochemical properties (pH, conductivity, bulk density and moisture content) and instrumental analysis using scanning electron microscopy (SEM) and Fourier Transform Infrared (FTIR). Two non- destructive analytical techniques; Dispersive X-ray Fluorescence Spectrometry (ED-XRF) and X-ray Diffraction (XRD) were adopted for heavy metals (elemental) composition and mineralogy respectively. The pH of printer ink and wood soot shows higher pH value which indicates that they are alkaline. Low conductivity values were reported with low moisture, indicating easy fragmentation and spreading. The bulk density values for samples shows that the soot can be easily spread by air current to the environment. The EDS analysis indicates that the soot particles to be composed of primarily impure carbon, thus pointing at potential organic pollutants. The IR spectra show characteristics signals at 749.2 cm-1, 745.5 cm-1, 738.0 cm-1 and 745.5 cm-1 for wood soot and printer ink which correspond to C-H of aromatic group, 1703.4 cm-1, 1699.7 cm-1. The XRF analysis reveals high concentration of Chromium and other toxic metals. The mineralogical components of the soot and printer ink samples revealed the presence of associated minerals. Generally, levels of toxic metal exceed the permissible legislative limit for air samples.
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Brüggemann, Martin, Nathalie Hayeck, Chloé Bonnineau, Stéphane Pesce, Peter A. Alpert, Sébastien Perrier, Christoph Zuth, Thorsten Hoffmann, Jianmin Chen, and Christian George. "Interfacial photochemistry of biogenic surfactants: a major source of abiotic volatile organic compounds." Faraday Discussions 200 (2017): 59–74. http://dx.doi.org/10.1039/c7fd00022g.
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Films of biogenic compounds exposed to the atmosphere are ubiquitously found on the surfaces of cloud droplets, aerosol particles, buildings, plants, soils and the ocean. These air/water interfaces host countless amphiphilic compounds concentrated there with respect to in bulk water, leading to a unique chemical environment. Here, photochemical processes at the air/water interface of biofilm-containing solutions were studied, demonstrating abiotic VOC production from authentic biogenic surfactants under ambient conditions. Using a combination of online-APCI-HRMS and PTR-ToF-MS, unsaturated and functionalized VOCs were identified and quantified, giving emission fluxes comparable to previous field and laboratory observations. Interestingly, VOC fluxes increased with the decay of microbial cells in the samples, indicating that cell lysis due to cell death was the main source for surfactants and VOC production. In particular, irradiation of samples containing solely biofilm cells without matrix components exhibited the strongest VOC production upon irradiation. In agreement with previous studies, LC-MS measurements of the liquid phase suggested the presence of fatty acids and known photosensitizers, possibly inducing the observed VOC productionviaperoxy radical chemistry. Up to now, such VOC emissions were directly accounted to high biological activity in surface waters. However, the results obtained suggest that abiotic photochemistry can lead to similar emissions into the atmosphere, especially in less biologically-active regions. Furthermore, chamber experiments suggest that oxidation (O3/OH radicals) of the photochemically-produced VOCs leads to aerosol formation and growth, possibly affecting atmospheric chemistry and climate-related processes, such as cloud formation or the Earth’s radiation budget.
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Sonexai, Phommachith, Minh Van Nguyen, Bui The Huy, and Yong-Ill Lee. "Silver-based SERS substrates fabricated using a 3D printed microfluidic device." Beilstein Journal of Nanotechnology 14 (July 21, 2023): 793–803. http://dx.doi.org/10.3762/bjnano.14.65.
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The detection of harmful chemicals in the environment and for food safety is a crucial requirement. While traditional techniques such as GC–MS and HPLC provide high sensitivity, they are expensive, time-consuming, and require skilled labor. Surface-enhanced Raman spectroscopy (SERS) is a powerful analytical tool for detecting ultralow concentrations of chemical compounds and biomolecules. We present a reproducible method for producing Ag nanoparticles that can be used to create highly sensitive SERS substrates. A microfluidic device was employed to confine the precursor reagents within the droplets, resulting in Ag nanoparticles of uniform shape and size. The study investigates the effects of various synthesis conditions on the size distribution, dispersity, and localized surface plasmon resonance wavelength of the Ag nanoparticles. To create the SERS substrate, the as-synthesized Ag nanoparticles were assembled into a monolayer on a liquid/air interface and deposited onto a porous silicon array prepared through a metal-assisted chemical etching approach. By using the developed microfluidic device, enhancement factors of the Raman signal for rhodamine B (at 10−9 M) and melamine (at 10−7 M) of 8.59 × 106 and 8.21 × 103, respectively, were obtained. The detection limits for rhodamine B and melamine were estimated to be 1.94 × 10−10 M and 2.8 × 10−8 M with relative standard deviation values of 3.4% and 4.6%, respectively. The developed SERS substrate exhibits exceptional analytical performance and has the potential to be a valuable analytical tool for monitoring environmental contaminants.
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Tuccella, P., G. Curci, G. A. Grell, G. Visconti, S. Crumeyrolle, A. Schwarzenboeck, and A. A. Mensah. "A new chemistry option in WRF-Chem v. 3.4 for the simulation of direct and indirect aerosol effects using VBS: evaluation against IMPACT-EUCAARI data." Geoscientific Model Development 8, no. 9 (September 4, 2015): 2749–76. http://dx.doi.org/10.5194/gmd-8-2749-2015.
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Abstract. A parameterization for secondary organic aerosol (SOA) production based on the volatility basis set (VBS) approach has been coupled with microphysics and radiative schemes in the Weather Research and Forecasting model with Chemistry (WRF-Chem) model. The new chemistry option called "RACM-MADE-VBS-AQCHEM" was evaluated on a cloud resolving scale against ground-based and aircraft measurements collected during the IMPACT-EUCAARI (Intensive Cloud Aerosol Measurement Campaign – European Integrated project on Aerosol Cloud Climate and Air quality interaction) campaign, and complemented with satellite data from MODIS. The day-to-day variability and the diurnal cycle of ozone (O3) and nitrogen oxides (NOx) at the surface are captured by the model. Surface aerosol mass concentrations of sulfate (SO4), nitrate (NO3), ammonium (NH4), and organic matter (OM) are simulated with correlations larger than 0.55. WRF-Chem captures the vertical profile of the aerosol mass concentration in both the planetary boundary layer (PBL) and free troposphere (FT) as a function of the synoptic condition, but the model does not capture the full range of the measured concentrations. Predicted OM concentration is at the lower end of the observed mass concentrations. The bias may be attributable to the missing aqueous chemistry processes of organic compounds and to uncertainties in meteorological fields. A key role could be played by assumptions on the VBS approach such as the SOA formation pathways, oxidation rate, and dry deposition velocity of organic condensable vapours. Another source of error in simulating SOA is the uncertainties in the anthropogenic emissions of primary organic carbon. Aerosol particle number concentration (condensation nuclei, CN) is overestimated by a factor of 1.4 and 1.7 within the PBL and FT, respectively. Model bias is most likely attributable to the uncertainties of primary particle emissions (mostly in the PBL) and to the nucleation rate. Simulated cloud condensation nuclei (CCN) are also overestimated, but the bias is more contained with respect to that of CN. The CCN efficiency, which is a characterization of the ability of aerosol particles to nucleate cloud droplets, is underestimated by a factor of 1.5 and 3.8 in the PBL and FT, respectively. The comparison with MODIS data shows that the model overestimates the aerosol optical thickness (AOT). The domain averages (for 1 day) are 0.38 ± 0.12 and 0.42 ± 0.10 for MODIS and WRF-Chem data, respectively. The droplet effective radius (Re) in liquid-phase clouds is underestimated by a factor of 1.5; the cloud liquid water path (LWP) is overestimated by a factor of 1.1–1.6. The consequence is the overestimation of average liquid cloud optical thickness (COT) from a few percent up to 42 %. The predicted cloud water path (CWP) in all phases displays a bias in the range +41–80 %, whereas the bias of COT is about 15 %. In sensitivity tests where we excluded SOA, the skills of the model in reproducing the observed patterns and average values of the microphysical and optical properties of liquid and all phase clouds decreases. Moreover, the run without SOA (NOSOA) shows convective clouds with an enhanced content of liquid and frozen hydrometers, and stronger updrafts and downdrafts. Considering that the previous version of WRF-Chem coupled with a modal aerosol module predicted very low SOA content (secondary organic aerosol model (SORGAM) mechanism) the new proposed option may lead to a better characterization of aerosol–cloud feedbacks.
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Wang, B., A. Zhang, J. L. Sun, H. Liu, J. Hu, and L. X. Xu. "Study of SARS Transmission Via Liquid Droplets in Air." Journal of Biomechanical Engineering 127, no. 1 (February 1, 2005): 32–38. http://dx.doi.org/10.1115/1.1835350.
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Abstract Microscale liquid droplets could act as the SARS carriers in air when released from an infected person through breathing, coughing, or sneezing. In this study, a dynamic model has been built to quantitatively investigate the effect of the relative humidity on the transport of liquid droplets in air using coupled mass transfer and momentum equations. Under higher relative humidity, the exhaled liquid droplets evaporate slowly. Larger droplets fall faster, which could reduce the probability of the droplets inhalation. This may be one of the most important factors that influence the SARS transmission in air.
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Khan, Mohidus Samad, Dushmantha Kannangara, Wei Shen, and Gil Garnier. "Isothermal Noncoalescence of Liquid Droplets at the Air−Liquid Interface." Langmuir 24, no. 7 (April 2008): 3199–204. http://dx.doi.org/10.1021/la7028627.
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Francis, Wayne, Cormac Fay, Larisa Florea, and Dermot Diamond. "Self-propelled chemotactic ionic liquid droplets." Chemical Communications 51, no. 12 (2015): 2342–44. http://dx.doi.org/10.1039/c4cc09214g.
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Xing, Lei, Jinyu Li, Minghu Jiang, and Lixin Zhao. "Dynamic behavior of compound droplets with millimeter-sized particles impacting substrates with different wettabilities." Physics of Fluids 35, no. 2 (February 2023): 022108. http://dx.doi.org/10.1063/5.0137505.
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The dynamic behavior of compound droplets, which are made up of a millimeter-sized particle and distilled water, impacting substrates of different wettabilities is investigated via high-speed photography. The effects of the size of the particle within the compound droplet, substrate contact angle, and impact height on the deformation of the droplets and the characteristics of the impact are analyzed. It is found that the collisions of compound droplets with substrates can be classified into four categories based on the observed experimental phenomena that occur during the impact. These categories are referred to as adhesion collision, rebound collision, daughter-droplet collision (or partial rebound collision), and breakup collision. We consider both the impact of water droplets and compound droplets (with one of two different-sized particles) on substrates of different wettabilities. The effects of inertia, surface tension, and adhesion between the substrate and the liquid droplet, and adhesion between the particle and the liquid droplet are considered to explain the different collision phenomena of compound droplets and reveal the evolution mechanism of the droplet morphologies in the experiments. Furthermore, the effects of the height from which the droplet is released and the contact angle of the substrate (i.e., its wettability) on the maximum spreading diameter and maximum jet height of the droplet are presented quantitatively. The effect of the size of the particle within the compound droplet and the substrate contact angle on the dynamic behavior of the compound droplet subject to impact with the substrate is also described.
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Xie, Ganhua, Joe Forth, Shipei Zhu, Brett A. Helms, Paul D. Ashby, Ho Cheung Shum, and Thomas P. Russell. "Hanging droplets from liquid surfaces." Proceedings of the National Academy of Sciences 117, no. 15 (March 27, 2020): 8360–65. http://dx.doi.org/10.1073/pnas.1922045117.
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Natural and man-made robotic systems use the interfacial tension between two fluids to support dense objects on liquid surfaces. Here, we show that coacervate-encased droplets of an aqueous polymer solution can be hung from the surface of a less dense aqueous polymer solution using surface tension. The forces acting on and the shapes of the hanging droplets can be controlled. Sacs with homogeneous and heterogeneous surfaces are hung from the surface and, by capillary forces, form well-ordered arrays. Locomotion and rotation can be achieved by embedding magnetic microparticles within the assemblies. Direct contact of the droplet with air enables in situ manipulation and compartmentalized cascading chemical reactions with selective transport. Applications including functional microreactors, motors, and biomimetic robots are evident.
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Al-Rawi, Omar, and Mark Wilson. "Influence of forced convection on the evaporation and internal dynamics inside of an array of salt solution droplets." MATEC Web of Conferences 240 (2018): 01002. http://dx.doi.org/10.1051/matecconf/201824001002.
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The effects of a gentle forced air convection on the internal dynamics of an array of multiple pinned sessile salt solution droplets are investigated via fully-coupled transient ALE finite element analysis. Results highlight the competition between the shear-induced circulation within the droplets and the gravity-driven flow in the droplets arising from increasing liquid density in regions of high water evaporation. At low air speeds, gravity effects dominate, resulting in a non-uniform concentration distribution. However, at higher speeds the shear-induced circulation within the droplets becomes sufficient to mix the liquid within the droplets via a 3D flow pattern, resulting in greater concentration uniformity. In addition, the shielding effect of leading droplets on downstream droplets is explored for various air speeds, with results showing differences in average concentration levels.
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Post, Scott L. "Drift of Droplets from Air-Induction Nozzles." Transactions of the ASABE 62, no. 6 (2019): 1683–87. http://dx.doi.org/10.13031/trans.13421.
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Abstract. For more than 20 years, air-induction or air-inclusion (AI) nozzles have had increased use for pesticide application due to their drift reduction capabilities. The pressure drop created by the pre-orifice and the venturi chamber results in a slower-moving liquid sheet exiting the main orifice, which in turn results in larger droplet sizes, which are less prone to drift. However, two additional factors somewhat mitigate the advantage of larger droplets from AI nozzles: the lower initial spray jet momentum from AI nozzles (compared to standard nozzles of the same flow rating at the same pressure) means that droplets from AI nozzles are more affected by lateral crosswind, and the lower effective liquid density of droplets from AI nozzles due to the presence of air inclusions means that AI droplets are more affected by aerodynamic drag than pure liquid droplets of comparable sizes from standard nozzles. In this work, theoretical and numerical models are developed to quantify these effects and develop tools for accurate drift prediction from sprayers using AI nozzles. The reduction in spray density due to the presence of air inclusions is in the range of 12% to 36%. This reduction in density affects the aerodynamic drift of the spray droplets, with the result that a droplet with 30% air inclusions would have the drift characteristics of a normal droplet with 20% smaller diameter. HighlightsSprays from air induction (AI) nozzles typically contain 12% to 36% air inclusions by volume.A droplet with 30% air inclusions would have the same drift characteristics as a water droplet of 20% smaller diameter.An analytical model is developed to predict the drift distances of small droplets. Keywords: Air induction, Droplet size, Nozzles, Pesticides, Sprayers.
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Hájek, Ondřej, Ondřej Cejpek, Milan Malý, František Prinz, and Miroslav Jícha. "A dispersion of a droplet flow on crossing wires in an air counterflow." EPJ Web of Conferences 264 (2022): 01016. http://dx.doi.org/10.1051/epjconf/202226401016.
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Liquid dispersion on a wire mesh is a phenomenon that is utilized in many industrial applications, such as rotating packed beds. It is a very simple method of liquid atomization without a need for complex nozzles. This research focuses on an elementary case of a liquid dispersion on a crossing of two wires. Experiments were carried out in a wind tunnel to elucidate the influence of counterflow air velocity on a liquid sheet and droplets. High-speed camera was used to capture the impact of droplets on the crossing. Images were then processed using MATLAB® addon PIVlab. The effect of the input parameters, including a liquid flow rate in the range of 3.8 to 12 kg/h and air flow velocity varying from 0 to 9 m/s on the angle and velocity of dispersed droplets downstream of the crossing, was investigated. Finally, a qualitative description of the dispersion was evaluated. Results show that with an increasing liquid flow rate, the droplets dispersed in a wider angle. On the other hand, the influence of the air counterflow is significant only for low liquid flow rates. The atomization rate, determined by the number of small droplets, was better for higher liquid flow rates.
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Cheng, H. P., and C. P. Chien. "Ejection Interaction of Two Adjacent Micropumps." Journal of Fluids Engineering 128, no. 4 (January 17, 2006): 742–50. http://dx.doi.org/10.1115/1.2201638.
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This research intends to apply thermal bubble micropumps to motorcycle’s fuel atomizer system with ink and Stoddard solvent as the work liquids, and then utilize computational fluid dynamics to discuss the fluid interaction of two adjacent micropumps under continuous ejection with time lag, which covers the particle shape and movement track of ejected droplets, fluid interaction of ejected droplets, and velocity of droplets as well as work liquid replenishment. The micropump consists of 50 independent micropumps, with orifice of 50μm in diameter and working frequency of 5kHz. As shown in results, when the external air velocity is 0m∕sec, the velocity of droplets ejected later is faster than that of droplets ejected earlier. If the work liquid is ink, the replenishing rate of two adjacent micropumps is higher than that of single micropump. If the work liquid is Stoddard solvent, the replenishing rate of two adjacent micropumps is similar to that of single micropump. When the external air velocity is 15.0m∕sec and work liquid is ink, the velocity of droplet ejected later is slower than that of droplet ejected earlier, and the replenishing rate of two adjacent micropumps is lower than that of single micropump with the external air velocity of 0m∕sec. If the work liquid is Stoddard solvent, the velocities of two adjacent droplets are approximate, while the replenishing rates of two adjacent micropumps are approximate to that of single micropump with the external air velocity of 0m∕sec.
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Han, Xiaotian, Hua Zhou, Yifei Zhu, Liangyu Wu, Feng Yao, and Cheng Yu. "Improvement of the Sphericity and the Thickness Uniformity of the Polystyrene (PS) Shell Microsphere during Curing Process." Coatings 9, no. 6 (June 14, 2019): 385. http://dx.doi.org/10.3390/coatings9060385.
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To improve the quality of dispersed polystyrene (PS) compound droplets, a new random rotating curing system is designed. In addition, the qualities of the curing products of the PS compound droplets of this new system are compared with those of the traditional curing system with a constant rotating speed, so as to verify the effectiveness of the new system on the quality improvement of the PS compound droplets. The effect of the liquid level, rotation rate and the density difference on the curing process is also analyzed to reveal the mechanism of the curing process in a rotating flow field. The results indicate that, in the new rotating curing system, the disturbance of the fluid increases the deformation recovery ability of the compound droplets. Furthermore, the vortex with different directions in the external flow fields, make the compound droplets spin in many directions, which improves the spheroidization and concentricity of the compound droplets. Compared with using the traditional rotating curing system, when utilizing the random rotating curing system, the sensitivity of the microspheres’ quality to the density mismatch between the phases is smaller, and the sphericity and the thickness uniformity of the polystyrene (PS) microsphere increase by 10.2% and 4.5%, respectively. In addition, there is an optimal rotation rate for the random rotating curing device, which can optimize the survival rate and quality of the hollow microspheres.
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Okamoto, Tatsuyuki, Toshimi Takagi, Toshikazu Kaji, Katsunori Shimazaki, and Kenji Nakanishi. "Studies on the Behavior of Droplets and the Air Flow in a Hollow-Cone Spray." Journal of Fluids Engineering 120, no. 3 (September 1, 1998): 586–92. http://dx.doi.org/10.1115/1.2820704.
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Experimental and numerical investigations are made on the behavior of droplets in a hollow-cone spray paying attention to the liquid sheet formed at the orifice of pressure-swirl atomizer. Simultaneous measurements of droplet sizes and velocities are made by phase-Doppler technique and numerical simulations are carried out based on the transient Eulerian equations for the gas and the Lagrangian equation for the droplets, taking account of the liquid sheet formed at the atomizer orifice. It is shown that the simulation gives good predictions by incorporating the existence of the liquid sheet. The predicted results indicate that the movement of the liquid sheet induces a strong air stream which acts as a strong side wind against the droplets immediately after breakup. This air stream selectively transports small droplets toward the central region and plays an essential role in the classification of droplets by size. Accordingly, the existence of the liquid sheet is significant for the characteristics of droplet dispersion and it should not be neglected in the prediction of hollow-cone spray flows. In addition, the shape of the liquid sheet is theoretically computed based on the simplified equations of motion. The comparison between the theoretical computation and the experimental result suggests that the surface tension of liquid is predominant in determining the shape of the liquid sheet.
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Lee, A., B. Utepov, E. Kan, and O. Kuychiev. "Study on the process of droplet formation when liquid flows out of a capillary." IOP Conference Series: Earth and Environmental Science 939, no. 1 (December 1, 2021): 012033. http://dx.doi.org/10.1088/1755-1315/939/1/012033.
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Abstract This article presents the theoretical background for the justification of the parameters of the rotating sprayer. Theoretical studies show that an increase in the rotation frequency of the disk at a constant air flow velocity leads to a minimum median mass diameter of the droplets. Therefore, when justifying the diameter of the sprayed droplets, it is necessary to consider the combination of the disk rotation speed and the axial velocity of the air flow. To obtain high-quality air-droplet flow, the initial speed of the main droplets discharged from the periphery of the spray disc should be less than the air velocity and rotational frequency Pavlovskyi spray is recommended to be applied with in ω=60… 200 c1.
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Ishizaka, Shoji, Chihiro Yamamoto, and Himeka Yamagishi. "Liquid–Liquid Phase Separation of Single Optically Levitated Water–Ionic Liquid Droplets in Air." Journal of Physical Chemistry A 125, no. 35 (August 25, 2021): 7716–22. http://dx.doi.org/10.1021/acs.jpca.1c06130.
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Ueno, Kazuyuki, Ghislain Bournival, Erica J. Wanless, Saori Nakayama, Emma C. Giakoumatos, Yoshinobu Nakamura, and Syuji Fujii. "Liquid marble and water droplet interactions and stability." Soft Matter 11, no. 39 (2015): 7728–38. http://dx.doi.org/10.1039/c5sm01584g.
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AWONORIN, S. O. "Evaporation Rates of Freely Falling Liquid Nitrogen Droplets in Air." Heat Transfer Engineering 10, no. 1 (January 1989): 26–36. http://dx.doi.org/10.1080/01457638908939689.
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QIAN, S. X., J. B. SNOW, H. M. TZENG, and R. K. CHANG. "Lasing Droplets: Highlighting the Liquid-Air Interface by Laser Emission." Science 231, no. 4737 (January 31, 1986): 486–88. http://dx.doi.org/10.1126/science.231.4737.486.
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Zakharevich, Arkadiy V., Mikhail S. Zygin, and Dmitriy N. Tsymbalov. "Ignition of liquid droplets fuels under conditions of radiation-conductive heating in air." MATEC Web of Conferences 194 (2018): 01062. http://dx.doi.org/10.1051/matecconf/201819401062.
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The results of an experimental investigation of ignition liquid fuel (kerosene, diesel fuel) by the single drops under conditions of radiation-conducting heating in air are presented. The dependences of the ignition delay time of the typical fuels droplets on the initial temperature of the heated oxidant in a limited space are established. The parameters of stable ignition of liquid fuel droplets are set.
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SCHMIDT, JOHN W., TERRANCE M. ARTHUR, JOSEPH M. BOSILEVAC, NORASAK KALCHAYANAND, and TOMMY L. WHEELER. "Detection of Escherichia coli O157:H7 and Salmonella enterica in Air and Droplets at Three U.S. Commercial Beef Processing Plants†." Journal of Food Protection 75, no. 12 (December 1, 2012): 2213–18. http://dx.doi.org/10.4315/0362-028x.jfp-12-206.
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Bacteria are known to be present in the air at beef processing plants, but published data regarding the prevalences of airborne Escherichia coli O157:H7 and Salmonella enterica are very limited. To determine if airborne pathogens were present in beef processing facilities, we placed sedimentation sponges at various locations in three commercial beef plants that processed cattle from slaughter through fabrication. For the 291 slaughter area air samples, E. coli O157:H7 was isolated from 15.8% and S. enterica from 16.5%. Of the 113 evisceration area air samples, E. coli O157:H7 was isolated from only one sample and S. enterica was not isolated from any sample. Pathogens were not isolated from any of the 87 air samples from fabrication areas. Pathogen prevalences, aerobic plate counts, and Enterobacteriaceae counts were highest for air samples obtained from locations near hide removal operations. The process of hide removal disperses liquid droplets, which may contact neighboring carcasses. Samples were obtained both from hide removal locations that were close enough to hide pullers to be contacted by droplets and from locations that were not contacted by droplets. Higher pathogen prevalences, aerobic plate counts, and Enterobacteriaceae counts were observed at locations with samples contacted by the hide removal droplets. We conclude that the hide removal processes likely introduce pathogens into the air via a dispersion of liquid droplets and that these droplets may be an underappreciated source of hide-to-carcass contamination.
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Chen, Dong Xuan, Xiao Kun OuYang, Yang Guang Wang, Li Ye Yang, Di Yu, and Chao Hong He. "Preparation of Uniform Microcapsules Containing Ionic Liquid for Caprolactam Extraction." Advanced Materials Research 557-559 (July 2012): 619–23. http://dx.doi.org/10.4028/www.scientific.net/amr.557-559.619.
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Microencapsulating ionic liquid is an effective way to overcome the loss of ionic liquid in the extraction process. A phase inversion method was used to form microcapsules containing 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM] [PF6]. The oil phase, composed of [BMIM][PF6], polysulfone and dichloromethane, was dropped into the 0.2 wt% gelatin aqueous solution using nitrogen gas pressure to form droplets. As dichloromethane evaporated completely, polysulfone microcapsules containing [BMIM] [PF6] were obtained. The microcapsules were characterized using a polarizing microscope, a laser particle size analyzer and a thermogravimetric analyzer. Moreover the microcapsules were performed some effect on caprolactam extraction from water.
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Zhao, Na, Yong Gang Yu, and Qi Zhang. "Experimental Study of the Counter Dual-Swirl Air Blast Atomizer." Applied Mechanics and Materials 130-134 (October 2011): 637–40. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.637.
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With the Phase Doppler Analyzer (PDA), the distribution characteristics of the liquid propellant simulated media produced by the designed counter dual-swirl air blast atomizer are studied. The results indicate that, the maximum axial mean velocity decreases with the increase of the axial distance away from the swirl exit plane, but the uniformity of the distribution along the radial direction are better and the differences among the degree axes decay. The circumferential distribution of the droplets’ diameter is uneven. The uniformity of the droplets’ diameter decreases after increases along with the radial direction. The mean diameters of the droplets increase first, and then decrease with the increase of the radial distance away from the center axis. The distribution of the droplets along the radial direction is better as the spray evolves to downstream.
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Schmidt, David J., William Kvasnak, and Goodarz Ahmadi. "A Model for Fuel Spray Formation with Atomizing Air." Fluids 4, no. 1 (January 29, 2019): 20. http://dx.doi.org/10.3390/fluids4010020.
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The formation of a liquid spray emanating from a nozzle in the presence of atomizing air was studied using a computational model approach that accounted for the deformation and break up of droplets. Particular attention was given to the formation of sprays under non-swirling flow conditions. The instantaneous fluctuating fluid velocity and velocity gradient components were evaluated with the use of a probability density function (PDF)-based Langevin equation. Motions of atomized fuel droplets were analyzed, and ensemble and time averaging were used for evaluating the statistical properties of the spray. Effects of shape change of droplets, and their breakup, as well as evaporation, were included in the model. The simulation results showed that the mean-square fluctuation velocities of the droplets vary significantly with their size and shape. Furthermore, the mean-square fluctuation velocities of the evaporating droplet differed somewhat from non-evaporating droplets. Droplet turbulence diffusivities, however, were found to be close to the diffusivity of fluid point particles. The droplet velocity, concentration, and size of the simulated spray were compared with the experimental data and reasonable agreement was found.
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Arghavani-Beydokhti, Somayeh, Alireza Asghari, Mohammad Bazregar, and Maryam Rajabi. "Application of a tandem air-agitated liquid–liquid microextraction technique based on solidification of floating organic droplets as an efficient extraction method for determination of cholesterol-lowering drugs in complicated matrices." RSC Advances 6, no. 96 (2016): 93582–89. http://dx.doi.org/10.1039/c6ra19414a.
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To enhance sample clean-up in dispersive liquid–liquid microextraction in complicated matrices, a low-toxicity and sensitive extraction method, tandem air-agitated liquid–liquid microextraction, based on solidification of floating organic droplets is introduced.
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Rashid, Mohd Syazwan Firdaus Mat, Ahmad Hussein Abdul Hamid, Chee Sheng Ow, and Zulkifli Abdul Ghaffar. "An Experimental Investigation on the Effect of Various Swirl Atomizer Orifice Geometries on the Air Core Diameter." Applied Mechanics and Materials 225 (November 2012): 32–37. http://dx.doi.org/10.4028/www.scientific.net/amm.225.32.
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Liquid atomization is a process of changing the liquid into small droplets. There are many applications which are related to liquid atomization including fuel injection in combustion systems and also in agricultural sprays. In pressure swirl atomizer, the liquid is injected into the atomizer through tangential port and a swirling motion is formed inside the swirl chamber. In high strength of swirling motion, an air core will be visible inside the atomizer. The liquid is then discharged from the orifice to form a spray which breaks up the liquid into small droplets. The objective of this research is to investigate the effect of various orifice geometries on the air core diameter. The injection pressure was varied in the range of 2 to 8 bar and water was used as the working fluid. Experiment data shows that the air core diameter increases as the injection pressure increased, regardless the discharge orifice diameter and discharge orifice length. It also found that the air core diameter increases as the discharge orifice length decreases and the discharge orifice diameter increases.
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Kuznetsov, Geniy, Svetlana Kralinova, Ivan Voytkov, and Anastasia Islamova. "Rates of High-Temperature Evaporation of Promising Fire-Extinguishing Liquid Droplets." Applied Sciences 9, no. 23 (November 29, 2019): 5190. http://dx.doi.org/10.3390/app9235190.
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Differences in the rates of heating and evaporation of droplets with the component composition are important parameters of heat transfer processes and phase transformations. This paper presents the values of high-temperature (up to 600 °C) evaporation rates of droplets of promising fire-extinguishing compositions (water, bentonite suspension, bischofite solution, EA-5 solution, and foaming agent emulsion) at convective (in the air stream), conductive (on a heated surface), and radiation (in a muffle furnace) heating. A high-speed video recording system and tracking software algorithms are used. At identical initial sizes of droplets of fire-extinguishing suspensions, known as emulsions and solutions, the times of their complete evaporation are shown to differ 3.7 times when heating on the substrate, 1.25 times in the air flow, and 1.9 times in the muffle furnace. A general approximation expression is formulated, and the empirical constants are calculated to predict the evaporation rate of the droplets of extinguishing agents in a wide range of temperatures (up to 600 °C) and heat fluxes (up to 100 kW/m2), which are characteristic of forest fires. With the use of the experimental data obtained, it is possible to predict the completeness of evaporation of promising extinguishing liquids at different schemes of heat supply.
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Bartoš, Ondřej, and Lucie Měšťanová. "AN EXPERIMENTAL STUDY OF THE COARSE DROPLETS FORMATION." Acta Polytechnica CTU Proceedings 20 (December 31, 2018): 10–15. http://dx.doi.org/10.14311/app.2018.20.0010.
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The paper introduces the first results from a new steam/air wind tunnel built in order to study the coarse water droplets in steam turbines and their formation. The wind tunnel was designed with the aim to have a testing facility with similar flow conditions for the study of liquid films as found in steam turbines. The tunnel is equipped with common devices for the measurement of the flow and for the analysis of the diameter distribution of the droplets. Two measurements methods were used for the measurement of the droplets size, photogrammetry and light scattering. The liquid film is artificially produced on an airfoil placed in the nozzle and liquid is pumped by a dosing pump on the surface of the airfoil. Coarse droplets formed from the liquid films have a negative effect on the reliability and efficiency of the turbines due to the erosion and corrosion by the droplets impact on the leading edges of the blades.
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Tarczy-Hornoch, Peter, Jack Hildebrandt, Thomas A. Standaert, and J. Craig Jackson. "Surfactant replacement increases compliance in premature lamb lungs during partial liquid ventilation in situ." Journal of Applied Physiology 84, no. 4 (April 1, 1998): 1316–22. http://dx.doi.org/10.1152/jappl.1998.84.4.1316.
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Treatments available to improve compliance in surfactant-deficient states include exogenous surfactant (ES) and either partial (PLV) or total liquid ventilation (TLV) with perfluorochemical (PFC). Because of the additional air-lung and air-PFC interfaces introduced during PLV compared with TLV, we hypothesized that compliance would be worse during PLV than during TLV. Because surfactant is able to reduce interfacial tension between air and lung as well as between PFC and lung, we further hypothesized that compliance would improve with surfactant treatment before PLV. In excised preterm lamb lungs, we used Survanta for surfactant replacement and perflubron as the PFC. Compliance during PLV was intermediate between TLV and gas inflation, both with and without surfactant. Surfactant improved compliance during PLV, compared with PLV alone. Because of the force-balance equation governing the behavior of immiscible droplets on liquid surfaces, we predict that PFC droplets spread during PLV to cover the alveolar surface in surfactant-deficient lungs during most of lung inflation and deflation but that the PFC would retract into droplets in surfactant-sufficient lungs, except at end inspiration.
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Hicks, Peter D., and Richard Purvis. "Air cushioning in droplet impacts with liquid layers and other droplets." Physics of Fluids 23, no. 6 (June 2011): 062104. http://dx.doi.org/10.1063/1.3602505.
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Toker, G. R., and J. Stricker. "Holographic study of suspended vaporizing volatile liquid droplets in still air." International Journal of Heat and Mass Transfer 39, no. 16 (November 1996): 3475–82. http://dx.doi.org/10.1016/0017-9310(96)00018-x.
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