scholarly journals Universal evaporation dynamics of ordered arrays of sessile droplets

2019 ◽  
Vol 866 ◽  
pp. 61-81 ◽  
Author(s):  
Sandeep Hatte ◽  
Keshav Pandey ◽  
Khushboo Pandey ◽  
Suman Chakraborty ◽  
Saptarshi Basu
Keyword(s):  
Near Field ◽  
Scaling Law ◽  
Present Theory ◽  
Solid Substrate ◽  
Local Concentration ◽  
Sessile Droplet ◽  
Droplet Array ◽  
Ordered Array ◽  
The One ◽  
Evaporation Dynamics

Manipulation of an array of surface droplets organised in an ordered structure turns out to be of immense consequence in a wide variety of applications ranging from photonics, near field imaging and inkjet printing on the one hand to bio-molecular analysis and DNA sequencing on the other. While evaporation of a single isolated sessile droplet has been well studied, the collective evaporative dynamics of an ordered array of droplets on a solid substrate remains elusive. Physically, the closed region between the centre and side droplets in the ordered array reduces the mobility of the diffusing vapour, resulting in its accumulation along with enhanced local concentration and a consequent increment in the lifetime of the centre droplet. Here, we present a theoretical model to account for evaporation lifetime scaling in closely placed ordered linear droplet arrays. In addition, the present theory predicts the limiting cases of droplet interaction; namely, critical droplet separation for which interfacial interaction ceases to exist and minimum possible droplet separation (droplets on the verge of coalescence) for which the droplet system achieves maximum lifetime scaling. Further experimental evidence demonstrates the applicability of the present scaling theory to extended dimensions of the droplet array, generalising our physical conjecture. It is also worth noting that the theoretical time scale is applicable across a wide variety of drop–substrate combinations and initial droplet volumes. We also highlight that the scaling law proposed here can be extended seamlessly to other forms of confinement such as an evaporating droplet inside a mini-channel, as encountered in countless applications ranging from biomedical engineering to surface patterning.

Grain boundary segregation in metals

1992 ◽  
Vol 50 (2) ◽  
pp. 1204-1205
Author(s):  
C.L. Briant
Keyword(s):  
Fracture Surface ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Material Properties ◽  
Electron Spectroscopy ◽  
High Vacuum ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Local Concentration ◽  
The One

Grain boundary segregation is the process by which solute elements in a material diffuse to the grain boundaries, become trapped there, and increase their local concentration at the boundary over that in the bulk. As a result of this process this local concentration of the segregant at the grain boundary can be many orders of magnitude greater than the bulk concentration of the segregant. The importance of this problem lies in the fact that grain boundary segregation can affect many material properties such as fracture, corrosion, and grain growth.One of the best ways to study grain boundary segregation is with Auger electron spectroscopy. This spectroscopy is an extremely surface sensitive technique. When it is used to study grain boundary segregation the sample must first be fractured intergranularly in the high vacuum spectrometer. This fracture surface is then the one that is analyzed. The development of scanning Auger spectrometers have allowed researchers to first image the fracture surface that is created and then to perform analyses on individual grain boundaries.

Determining Micro Droplet Profile Using Internal Reflection Interference Fringes

2020 ◽  
Author(s):  
Iltai Isaac Kim ◽  
Yang Li ◽  
Jaesung Park
Keyword(s):  
Contact Angle ◽  
Liquid Droplet ◽  
Surface Profile ◽  
Morphological Features ◽  
Internal Reflection ◽  
Sessile Droplet ◽  
Spherical Droplet ◽  
Interference Fringes ◽  
The One ◽  
Air Liquid Interface

Abstract We introduce an optical diagnostics to determine the morphological features of liquid droplet such as the thickness, the contact angle, and the dual profile using internal reflection interferometry. A coherent laser beam is internally reflected on the air/liquid interface of a sessile droplet placed on a prism-based substrate to produce an interference fringe on a screen far from the substrate. The reflected laser rays consist of the reflection from the center spherical droplet profile and the one from the lower hyperbola-like droplet profile. The reflected rays are interfered each other to form the interference fringes. Ray tracing simulation is conducted using a custom-designed computer program. The simulation shows that the interfering rays reflected near the inflection point produce the outer-most fringes of the concentric interference pattern on the screen, and the reflected rays from the apex of the spherical profile and the contact line of the lower hyperbola-like profile construct the fringes at the center of the interference patterns. The simulated results are compared with the experimental observation to show a good agreement in the number and the location of the fringes and the radius of the outer-most-fringe where the number of the fringes is dependent on the droplet thickness and the radius of the fringe depends on the contact angle of the droplet. This result provides a new measurement technique to determine the morphological features of very small microdroplet such as the thickness (< a few micron thickness), the contact angle (< a few degree), and the dual-surface profile.

scholarly journals Evaporation of water: evaporation rate and collective effects

2016 ◽  
Vol 798 ◽  
pp. 774-786 ◽  
Author(s):  
Odile Carrier ◽  
Noushine Shahidzadeh-Bonn ◽  
Rojman Zargar ◽  
Mounir Aytouna ◽  
Mehdi Habibi ◽  
...  
Keyword(s):  
Evaporation Rate ◽  
Scaling Law ◽  
Solid Substrate ◽  
Collective Effects ◽  
Water Evaporation ◽  
Length Scale ◽  
Onset Of Convection ◽  
Cooperative Effects ◽  
Evaporative Flux ◽  
Drop Size Distributions

We study the evaporation rate from single drops as well as collections of drops on a solid substrate, both experimentally and theoretically. For a single isolated drop of water, in general the evaporative flux is limited by diffusion of water through the air, leading to an evaporation rate that is proportional to the linear dimension of the drop. Here, we test the limitations of this scaling law for several small drops and for very large drops. We find that both for simple arrangements of drops, as well as for complex drop size distributions found in sprays, cooperative effects between drops are significant. For large drops, we find that the onset of convection introduces a length scale of approximately 20 mm in radius, below which linear scaling is found. Above this length scale, the evaporation rate is proportional to the surface area.

An Examination of Flow Regimes Associated With Inkjet-Printed Colloidal Drops

2008 ◽  
Author(s):  
Vadim Bromberg ◽  
Sailee Gawande ◽  
Ying Sun ◽  
Timothy Singler
Keyword(s):  
Experimental Study ◽  
Radial Flow ◽  
Internal Flow ◽  
Flow Regimes ◽  
Solid Substrate ◽  
Marangoni Flow ◽  
Single Group ◽  
Evaporation Dynamics

An experimental study of the evaporation dynamics for an inkjet-printed drop on a solid substrate has been attempted. Using fluorescent spherical colloids, the internal flow of an evaporating drop has been observed directly. During the initial stages of the process, a novel inward radial flow carries the particles as a single group towards the center of the drop. Once the particles have converged near the center, a significantly slower outward radial flow proceeds. These flow regimes are qualitatively analyzed and their relationship to a possible thermal Marangoni flow is discussed.

scholarly journals Dual-Probe Near-Field Phaseless Antenna Measurement System on Board a UAV

Sensors ◽  
2019 ◽  
Vol 19 (21) ◽  
pp. 4663 ◽  
Author(s):  
María García Fernández ◽  
Yuri Álvarez López ◽  
Fernando Las-Heras
Keyword(s):  
Measurement System ◽  
Phase Retrieval ◽  
Near Field ◽  
Field Measurements ◽  
Dual Band ◽  
Antenna Measurement ◽  
Antenna Performance ◽  
Simultaneous Acquisition ◽  
Recent Developments ◽  
The One

On-site antenna measurement has been recently attracting an increasing interest in order to assess the antenna performance in real operational environments. The complexity and cost of these kind of measurements have been significantly cut down due to recent developments in unmanned aerial vehicles’ (UAVs) hardware and antenna measurement post-processing techniques. In particular, the introduction of positioning and geo-referring subsystems capable of providing centimeter-level accuracy together with the use of phase retrieval techniques and near-field to far-field transformation algorithms, have enabled near field measurements using UAVs. This contribution presents an improved UAV-based on-site antenna measurement system. On the one hand, the simultaneous acquisition on two measurement surfaces has been introduced and calibrated properly, thus reducing geo-referring uncertainties and flight time. On the other hand, the positioning and geo-referring subsystem has been enhanced by means of a dual-band real time kinematics (RTK) unit. The system capabilities were validated by measuring an offset reflector antenna, and the results were compared with the measurements at the spherical range in the anechoic chamber and with the measurements collected with a previous version of the implemented system.

Ring-Shaped Sessile Droplet

2011 ◽  
Author(s):  
Svyatoslav S. Chugunov ◽  
Douglas L. Schulz ◽  
Iskander S. Akhatov
Keyword(s):  
Contact Angle ◽  
Liquid Droplet ◽  
Liquid Structure ◽  
Solid Substrate ◽  
Contact Angles ◽  
Equilibrium Contact Angle ◽  
Sessile Droplet ◽  
System Equilibrium ◽  
Energy Consideration ◽  
External Forces

It is recognized that small liquid droplet placed on the solid substrate forms equilibrium contact angle that can be obtained from well-known Young’s law. Previously, deviations from Young’s law were demonstrated for the droplets exposed to external fields (gravity, electric, etc) and for the droplets on non-homogeneous substrates. This work reveals that the Young’s equilibrium contact angle can be altered by geometrical reasons only. We consider a ring-shaped droplet on a solid substrate as a test structure for our discussion. We use the global energy consideration for analysis of system equilibrium for the case of freely deposited liquid with no external forces applied. The theoretical analysis shows that steady ring-shaped liquid structure on a solid substrate does exist with contact angles on both contact lines to be different from the Young’s equilibrium contact angle.

Evaporation dynamics of a sessile droplet on glass surfaces with fluoropolymer coatings: focusing on the final stage of thin droplet evaporation

Soft Matter ◽  
2018 ◽  
Vol 14 (10) ◽  
pp. 1811-1821 ◽  
Author(s):  
Elizaveta Ya. Gatapova ◽  
Anna M. Shonina ◽  
Alexey I. Safonov ◽  
Veronica S. Sulyaeva ◽  
Oleg A. Kabov
Keyword(s):  
Final Stage ◽  
Liquid Droplet ◽  
Droplet Evaporation ◽  
Sessile Droplet ◽  
Evaporation Dynamics ◽  
Glass Surfaces

Liquid droplet on the “soft” coating can finalize as very thin droplet completely wetting the surface. We detail the thin droplet evaporation dynamics by image-analyzing interference technique.

Bandwidth enhancement of capacitive fed monopole antenna using parasitic patches

2015 ◽  
Vol 8 (2) ◽  
pp. 301-307 ◽  
Author(s):  
Kamalaveni Ayyadurai ◽  
Ganesh Madhan Muthu
Keyword(s):  
Near Field ◽  
Ground Plane ◽  
Monopole Antenna ◽  
Impedance Bandwidth ◽  
Bandwidth Enhancement ◽  
System A ◽  
Radiating Element ◽  
The One ◽  
Radio Band ◽  
5 Ghz

This paper proposed a compact planar monopole antenna operating at 5 GHz (5.180–5.825 GHz) industrial, scientific and medical (ISM) radio band. The antenna constructed with 20 mm × 12 mm radiating element and 25 mm square of the ground plane in FR4 substrate provided −10 dB bandwidth of 1 GHz (5.4–6.4 GHz). To improve the bandwidth, parasitic elements are added with the monopole antenna. A capacitive feed is also incorporated in the design. It observed that the proposed antenna with parasitic elements provides a larger impedance bandwidth of about 3 GHz (5.1–8.1 GHz), which is three-fold improvements over the one without parasitic patches. The prototype of the antenna that operates at 5.8 GHz frequency range is fabricated and characterized using a near-field measurement system. A good agreement is found between the simulation and measured results.

Effects of Local Concentration on Freezing Solutions of Winter Flounder Antifreeze Protein

2011 ◽  
Author(s):  
Yoshimichi Hagiwara ◽  
Ryo Sakurai ◽  
Daichi Yamamoto ◽  
Atsuhide Kitagawa
Keyword(s):  
Interface Velocity ◽  
Antifreeze Protein ◽  
Winter Flounder ◽  
Local Concentration ◽  
Measured Intensity ◽  
Solution Interface ◽  
Inverted Microscope ◽  
Peltier Device ◽  
The One ◽  
Directional Freezing

We have carried out experiments on the one-directional freezing of an aqueous solution of winter flounder antifreeze protein in a narrow gap between two cover glasses. The motion of the ice/solution interface has been observed with an inverted microscope. The solution has been cooled by a Peltier device. The local change in protein concentration has been estimated from the measured intensity of fluorescence from molecules tagged to the protein. It is found that highly-concentrated regions of the protein can be observed in the bottom edge of the serrated interface. These regions interact with the interface, though most of the protein diffuses due to the concentration gradient. The diffusion velocity is much lower than the interface velocity. Thus, the protein is accumulated near the interface.

LYAPUNOV SPECTRA OF CORRELATED RANDOM MATRIX PRODUCTS

2000 ◽  
Vol 14 (09) ◽  
pp. 291-301
Author(s):  
TSUNEYASU OKABE ◽  
HIROAKI YAMADA
Keyword(s):  
Correlation Function ◽  
Lyapunov Exponent ◽  
Scaling Law ◽  
Strongly Correlated ◽  
Maximal Lyapunov Exponent ◽  
Statistical Property ◽  
Lyapunov Spectra ◽  
Matrix Products ◽  
Strength Dependence ◽  
The One

We have numerically studied the Lyapunov spectra and the maximal Lyapunov exponent (MLE) in products of real symplectic correlated random matrices, each of which is produced by a modified Bernoulli map. As a statistical property, it has been well studied that the correlation function of the sequence of the map shows power-low decay. We can systematically investigate the influence of the correlation on the Lyapunov spectra and the fluctuation-strength dependence of the MLE. It is shown that the form of the scaled Lyapunov spectra does not change even if the correlation increases in the stationary region of the sequence, and in the nonstationary region, the form is quite different from the one in the stationary region. The power of the scaling law for the fluctuation-strength dependence of the MLE becomes small as the correlation increases, and a different scaling law can be observed in the strongly correlated nonstationary region as from the δ-correlated case.

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