scholarly journals Calcium Carbonate Mineralization in a Surface-Tension-Confined Droplets Array

Crystals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 284 ◽  
Author(s):  
Zhong He ◽  
Zengzilu Xia ◽  
Mengying Zhang ◽  
Jinbo Wu ◽  
Weijia Wen
Keyword(s):  
Surface Tension ◽  
Calcium Carbonate ◽  
Organic Molecule ◽  
Droplet Diameter ◽  
Experimental Methods ◽  
Characterization Methods ◽  
Array Technology ◽  
Article Surface ◽  
High Throughput Experiments ◽  
Rapid Drop

Calcium carbonate biomimetic crystallization remains a topic of interest with respect to biomineralization areas in recent research. It is not easy to conduct high-throughput experiments with only a few macromolecule reagents using conventional experimental methods. However, the emergence of microdroplet array technology provides the possibility to solve these issues efficiently. In this article, surface-tension-confined droplet arrays were used to fabricate calcium carbonate. It was found that calcium carbonate crystallization can be conducted in surface-tension-confined droplets. Defects were found on the surface of some crystals, which were caused by liquid flow inside the droplet and the rapid drop in droplet height during the evaporation. The diameter and number of crystals were related to the droplet diameter. Polyacrylic acid (PAA), added as a modified organic molecule control, changed the CaCO3 morphology from calcite to vaterite. The material products of the above experiments were compared with bulk-synthesized calcium carbonate by scanning electron microscopy (SEM), Raman spectroscopy and other characterization methods. Our work proves the possibility of performing biomimetic crystallization and biomineralization experiments on surface-tension-confined microdroplet arrays.

scholarly journals Spray adjuvant characteristics affecting agricultural spraying drift

2015 ◽  
Vol 35 (1) ◽  
pp. 109-116 ◽  
Author(s):  
RONE B. DE OLIVEIRA ◽  
ULISSES R. ANTUNIASSI ◽  
MARCO A. GANDOLFO
Keyword(s):  
Surface Tension ◽  
Wind Tunnel ◽  
Aqueous Solutions ◽  
Formation Process ◽  
Droplet Diameter ◽  
Brilliant Blue ◽  
Medium Size ◽  
Blue Dye ◽  
Methods Of Evaluation ◽  
Spray Adjuvants

This study defined the main adjuvant characteristics that may influence or help to understand drift formation process in the agricultural spraying. It was evaluated 33 aqueous solutions from combinations of various adjuvants and concentrations. Then, drifting was quantified by means of wind tunnel; and variables such as percentage of droplets smaller than 50 μm (V50), 100 μm (V100), diameter of mean volume (DMV), droplet diameter composing 10% of the sprayed volume (DV0.1), viscosity, density and surface tension. Assays were performed in triplicate, using Teejet XR8003 flat fan nozzles at 200 kPa (medium size droplets). Spray solutions were stained with Brilliant Blue Dye at 0.6% (m/ v). DMV, V100, viscosity cause most influence on drift hazardous. Adjuvant characteristics and respective methods of evaluation have applicability in drift risk by agricultural spray adjuvants.

scholarly journals Aerosol hygroscopicity at high (99 to 100%) relative humidities

2009 ◽  
Vol 9 (4) ◽  
pp. 15595-15640 ◽  
Author(s):  
C. R. Ruehl ◽  
P. Y. Chuang ◽  
A. Nenes
Keyword(s):  
Surface Tension ◽  
Inorganic Compounds ◽  
Droplet Diameter ◽  
Pure Water ◽  
Sodium Dodecyl ◽  
Bulk Solution ◽  
Active Compounds ◽  
Surface Active ◽  
Surface Active Compounds ◽  
Aerosol Hygroscopicity

Abstract. The hygroscopicity of an aerosol largely determines its influence on climate and, for smaller particles, atmospheric lifetime. While much aerosol hygroscopicity data is available at lower relative humidities (RH) and under cloud formation conditions (RH>100%), relatively little data is available at high RH (99.2 to 99.9%). We measured the size of droplets at high RH that had formed on particles composed of one of seven compounds with dry diameters between 0.1 and 0.5 μm, and calculated the hygroscopicity of these compounds. We use a parameterization of the Kelvin term, in addition to a standard parameterization (κ) of the Raoult term, to express the hygroscopicity of surface-active compounds. For inorganic compounds, hygroscopicity could reliably be predicted using water activity data and assuming a surface tension of pure water. In contrast, most organics exhibited a slight to mild increase in hygroscopicity with droplet diameter. This trend was strongest for sodium dodecyl sulfate (SDS), the most surface-active compound studied. The results suggest that partitioning of surface-active compounds away from the bulk solution, which reduces hygroscopicity, dominates any increases in hygroscopicity due to reduced surface tension. This is opposite to what is typically assumed for soluble surfactants. Furthermore, we saw no evidence that micellization limits SDS activity in micron-sized solution droplets, as observed in macroscopic solutions. These results suggest that while the high-RH hygroscopicity of inorganic compounds can be reliably predicted using readily available data, surface-activity parameters obtained from macroscopic solutions with organic solutes may be inappropriate for calculations of the hygroscopicity of micron-sized droplets.

Effect of Nanoparticles on the Fuel Properties and Spray Performance of Aviation Turbine Fuel

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Kumaran Kannaiyan ◽  
Kanjirakat Anoop ◽  
Reza Sadr
Keyword(s):  
Surface Tension ◽  
Physical Properties ◽  
Droplet Diameter ◽  
Cone Angle ◽  
Aviation Fuel ◽  
Alumina Nanoparticles ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Breakup Length ◽  
Sheet Breakup

The influence of nanoparticles' dispersion on the physical properties of aviation fuel and its spray performance has been investigated in this work. To this end, the conventional Jet A-1 aviation fuel and its mixtures with alumina nanoparticles (nanofuel) at different weight concentrations are investigated. The key fuel physical properties such as density, viscosity, and surface tension that are of importance to the fuel atomization process are measured for the base fuel and nanofuels. The macroscopic spray features like spray cone angle and sheet breakup length are determined using the shadowgraph technique. The microscopic spray characteristics such as droplet diameter, droplet velocity, and their distributions are also measured by employing phase Doppler anemometry (PDA) technique. The spray performance is measured at two nozzle injection pressures of 0.3 and 0.9 MPa. The results show that with the increase in nanoparticle concentrations in the base fuel, the fuel viscosity and density increase, whereas the surface tension decreases. On the spray performance, the liquid sheet breakup length decreases with increasing nanoparticle concentrations. Furthermore, the mean droplet diameters of nanofuel are found to be lower than those of the base fuel.

scholarly journals Microbial-induced calcium carbonate precipitation: an experimental toolbox for in situ and real time investigation of micro-scale pH evolution

RSC Advances ◽  
2020 ◽  
Vol 10 (35) ◽  
pp. 20485-20493
Author(s):  
Jennifer Zehner ◽  
Anja Røyne ◽  
Alexander Wentzel ◽  
Pawel Sikorski
Keyword(s):  
Calcium Carbonate ◽  
Real Time ◽  
Experimental Methods ◽  
Carbonate Precipitation ◽  
Calcium Carbonate Precipitation ◽  
Micro Scale ◽  
Ph Changes ◽  
Global And Local ◽  
Local Ph

We present two novel experimental methods to follow global and local pH changes on a microscale in bio-cementation processes.

Dynamic Behavior of Liquid Mercury Droplets Colliding with a Solid Surface

2014 ◽  
Vol 566 ◽  
pp. 391-396
Author(s):  
Takashi Naoe ◽  
Masatoshi Futakawa
Keyword(s):  
Surface Tension ◽  
Dynamic Behavior ◽  
Solid Surface ◽  
High Speed ◽  
Droplet Diameter ◽  
High Surface ◽  
Quartz Plate ◽  
Bubble Collapse ◽  
Fundamental Study ◽  
Liquid Mercury

The dynamic behavior of liquid mercury and water droplets colliding with a solid surface were precisely examined as part of a fundamental study for investigating the behavior of a liquid microjet emitted as a result of a cavitation bubble collapse in mercury. Liquid droplets were collided with a quartz plate by the free-fall method, and the colliding and spreading behaviors of the liquids were observed using a high-speed video camera. In the case of mercury droplets, the spreading, recoiling, and jump-up phenomena resulting from the high surface tension of mercury were observed. The ratio of the maximum spreading diameter,Dmax, to the initial droplet diameter,D0, was investigated by parametrically changing the colliding velocity and tilt-angle of the quartz plate. The result showed that the ratioDmax/D0was well correlated with the Weber number, which is defined as a function of the colliding velocity and surface tension, independent of the liquid considered.

Development and Validation of a Mathematical Model of Microfilm Formation in Atomization Cooling of Micromachining

2011 ◽  
Author(s):  
Kyle J. Boughner ◽  
John E. Wentz ◽  
Benton J. Garske
Keyword(s):  
Surface Tension ◽  
Film Thickness ◽  
Rotational Velocity ◽  
Droplet Diameter ◽  
Thickness Effect ◽  
Delivery Tube ◽  
Air Velocity ◽  
Cooling Rates ◽  
System Parameters ◽  
Cutting Zone

Traditional flood cooling processes can cause problems in micromachining due to the collision force between the fluid stream and the tool being greater in magnitude than the cutting forces. The traditional processes produce insufficient cooling rates and are unable to effectively evacuate chips from the cutting zone. Atomization-based cooling addresses these issues through high evaporative cooling rates, low impact forces, and the use of a high velocity air stream to clear the cutting zone of chips. This paper presents a probabilistic model to determine the thickness of a microfilm forming on a rotating cylindrical surface, such as a microturning workpiece or a microendmill, and the relative importance of system parameters on film formation. The rate of microfilm formation is dependent upon droplet losses in the tube, at the nozzle, and the scatter of the atomized spray. Droplet diameters and Weber numbers in the tube and at the cylinder were experimentally determined and modeled as lognormally distributed. Parameters investigated in this model are fluid and mist properties (surface tension and droplet size) and system parameters (delivery tube air velocity, spray air velocity, spray geometry, cylinder diameter, and cylinder rotational velocity). A maximum film thickness effect was found for the variables of delivery tube velocity, droplet diameter, and surface tension with a value for each variable that provided a thickest film. As the variables increased or decreased from that value the film thickness decreased.

Development and Modeling of Melt Electrohydrodynamic-Jet Printing of Phase-Change Inks for High-Resolution Additive Manufacturing

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Chuang Wei ◽  
Jingyan Dong
Keyword(s):  
Surface Tension ◽  
Additive Manufacturing ◽  
High Resolution ◽  
Phase Change ◽  
Electrostatic Force ◽  
Droplet Diameter ◽  
Scaling Law ◽  
Process Conditions ◽  
Drop On Demand ◽  
Jet Printing

This paper presents the development and modeling a high-resolution electrohydrodynamic-jet (EHD-jet) printing process using phase-change ink (i.e., wax), which is capable of producing sub-10 μm footprints (sub-10 fL in volume) for super-resolution additive manufacturing. In this study, we successfully apply EHD-jet printing for phase-change ink (wax), which is widely used as modeling and supporting material for additive manufacturing, to achieve micron-scale features. The resolution for single droplet on substrate is around 5 μm with the thickness in the range of 1–2 μm, which provides great potential in both high-resolution 3D printing and 2D drop-on-demand microfabrication. The droplet formation in EHD printing is modeled by finite element analysis (FEA). Two important forces in EHD printing, electrostatic force and surface tension force, are modeled separately by FEA. The droplet size is obtained by balancing the electrostatic force and surface tension of the pending droplets around meniscus apex. Furthermore, to predict the droplet dimension at different process conditions, a dimensionless scaling law is identified to describe the relationship between dimensionless droplet diameter and modified nondimensional electrical bond number. Finally, the droplets in-flight velocity and impact characteristics (e.g., Reynolds number and Weber number) are modeled using the results from FEA analysis.

scholarly journals Effect of Marangoni Convection in a Droplet Containing Surfactant on Thin Film Shape

2021 ◽  
Vol 333 ◽  
pp. 03002
Author(s):  
Kazuki Matsuda ◽  
Tenshin Oyama ◽  
Hirotaka Ishizuka ◽  
Shuji Hironaka ◽  
Jun Fukai
Keyword(s):  
Thin Film ◽  
Surface Tension ◽  
Marangoni Convection ◽  
Printed Electronics ◽  
Film Formation ◽  
Droplet Diameter ◽  
Evaporation Process ◽  
Polystyrene Solution ◽  
Fluorescent Polymer ◽  
The Relationship

In printed electronics, uniform and solute film formation by the inkjet method is very important. This study aims to clarify the relationship between Marangoni convection generated by adding surfactant and thinning of solute film. First, four types of surfactants were added one by one to the anisole-polystyrene solution with varying concentrations, and then a little amount of fluorescent polymer was added as tracer to each solution. Next, each solution was dropped on a hydrophilic substrate with a droplet diameter of 80 micrometers using an inkjet method, and the flow in the evaporation process and the shape of the solute film after drying were observed. As a result, Marangoni convection occurred when any surfactant was added at a certain concentration or more, and the solute film after drying of the droplets to which two kinds of surfactants were added became thin and approached a uniform shape. In addition, the measurement of surface tension showed that the visualized flow is the Marangoni convection.

The Effects of Surfactant on Simplex Nozzle Spray Behavior and its Comparison to Liquid Fuels

2013 ◽  
Author(s):  
Ashkan Davanlou ◽  
Joshua Lee ◽  
Saptarshi Basu ◽  
Ranganathan Kumar
Keyword(s):  
Experimental Study ◽  
Surface Tension ◽  
Numerical Models ◽  
Droplet Diameter ◽  
Pure Water ◽  
Diagnostic Technique ◽  
Injection Pressure ◽  
Droplet Breakup ◽  
Spray Angle ◽  
Breakup Length

Pressure-swirl nozzles (simplex nozzles) are used in various field applications such as aero-engines, power generation, spray painting and agricultural irrigation. For this particular nozzle, research in the past decade has dealt with the development of numerical models for predicting droplet distribution profiles. Although these results have been valuable, the experimental results have been contradictory, therefore fundamental understanding of the influence of properties in nozzle is important. This paper experimentally investigates the effect of surfactants on breakup and coalescence. Since most of the fuels and biofuels have low surface tension compared to water, a comparative analysis between a surfactant solution and a liquid fuel is imperative. For this experimental study, a simplex nozzle characterized as flow number 0.4 will be utilized. The injection pressures will range from 0.3–4Mpa while altering the surface tension from 72 to 28mN/m. By applying Phase Doppler Particle Anemometry (PDPA) which is a non-intrusive laser diagnostic technique, the differences in spray characteristics due to spray surface tension can be highlighted. The average droplet diameter decreases for a low surface tension fluid in the axial direction in comparison to pure water. The average velocity of droplets is surprisingly lower in the same spray zone. Measurements made in the radial direction show no significant changes, but at the locations close to the nozzle, water droplets have larger diameter and velocity. The results indicate the breakup and coalescence regimes have been altered when surface tension is lowered. A decrease in surface tension alters the breakup length while increasing the spray angle. Moreover, higher injection pressure shortens the breakup length and decrease in overall diameter of the droplets. By performing this experimental study the fundamentals of spray dynamics, such as spray formation, liquid breakup length, and droplet breakup regimes can be observed as a function of surface tension and how a surrogate fuel compares with a real fuel for experimental purposes. This knowledge potentially will lead to designing a better atomizer or new biofuels.

scholarly journals Numerical simulations and experiments on droplet coalescence dynamics over a liquid–air interface: mechanism and effect of droplet-size/surface-tension

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Javed Shaikh ◽  
Nagesh D. Patil ◽  
Atul Sharma ◽  
Rajneesh Bhardwaj
Keyword(s):  
Surface Tension ◽  
Excellent Agreement ◽  
Numerical Study ◽  
Droplet Diameter ◽  
Bond Number ◽  
Liquid System ◽  
Critical Values ◽  
Surface Tension Coefficient ◽  
Droplet Coalescence ◽  
Partial Coalescence

AbstractPresent study is on partial/complete coalescence dynamics of a droplet (surrounded by air) over a horizontal pool of the same liquid. Experimental and numerical studies are presented for both isopropanol and glycerol droplet of a constant diameter. Numerical study is presented in more detail for the isopropanol droplet to study the effect of diameter ($$D=0.035-6.7 mm$$ D = 0.035 - 6.7 m m ) and surface tension coefficient ($$\gamma =2-200 mN/m$$ γ = 2 - 200 m N / m ) on the coalescence dynamics. For partial coalescence of an isopropanol droplet and complete coalescence of a glycerol droplet, excellent agreement is demonstrated between our numerically and experimentally obtained interface dynamics; and a qualitative discussion on the mechanism of the partial and complete coalescence is presented. Three regimes of partial coalescence − viscous, inertio-capillary and gravity − proposed in the literature for a liquid-liquid system are presented here for the present liquid-air system while studying the effect of diameter of the isopropanol droplet. Probably for the first time in the literature, our numerical study presents a flow and vorticity dynamics based quantitativeevidence of the coalescence-mechanism, analogy with a freely vibrating Spring-Mass-Damper System, the gravity regime for a liquid-gas system, and the effect of surface tension coefficient $$\gamma$$ γ based coalescence dynamics study. The associated novel $$\gamma$$ γ based droplet coalescence regime map presents a critical Ohnesorge number $$Oh_{c}$$ O h c and critical Bond number $$Bo_{c}$$ B o c for a transition from partial to full coalescence; and such critical values are also presented for the transition under effect of the droplet diameter. The critical values based transition boundaries, obtained separately for the varying D and varying $$\gamma$$ γ , are demonstrated to be in excellent agreement with a correlation reported in the literature.

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