Dissertations / Theses on the topic 'Sessile Drops'
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Baughman, Kyle. "Deposition of Bacteria from Sessile Drops." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/194109.
Full textBou-Zeid, Wassim. "Wettability and evaporation of sessile drops of biological fluids." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4348/document.
Full textSpreading/evaporation process of droplets over solid surfaces is a fundamental process and a wide research field because of number of applications in printing, micro-electronics, DNA analysis and even in biomedical. This experimental work aims to investigate the effect of relative humidity on the contact line dynamics, on the evaporation dynamics and on the final pattern of a drop of whole human blood. The spreading of a pure fluid model that has the same physical properties as human blood was studied and compared to the blood. We showed that bio-colloids play significant effect on the dynamics of contact line and the pinning effect of the drop. For low contact angles, we showed that the spreading/evaporation process could be divided into two regimes. A fast first regime determined by a balance between viscous forces and capillary forces and a second slower regime dominated by the evaporation rate. Physical mechanisms that are responsible for the spreading enhancement are proposed and discussed. The average velocity of the contact line was found to follow the same behaviour as Tanner's model, where the spreading dynamics and geometrical parameters of the droplet are function of relative humidity. The experimental measurements are in a good agreement with the purely diffusive model where the equilibrium wetting radius and contact angle are function of relative humidity. For the morphological analysis of crack patterns, a manual segmentation method was used as a reference for the validation of the automatic developed segmentation method. We showed that the evaporation rate influences structural distribution of plaques in the corona region and hence, the mean crack spacing
Zhang, Ying. "Coalescence of Sessile Drops: the Role of Gravity, Interfacial Tension and Surface Wettability." Research Showcase @ CMU, 2016. http://repository.cmu.edu/dissertations/994.
Full textCarle, Florian. "Flow motion in sessile droplets : evaporation and nanoparticles assembly." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4726/document.
Full textSessile droplets are widely found in day to day life: it might be a coffee spilt, rain onto a waterproof raincoat or again, water falling onto a cooking plate. However, despite the vast number of studies devoted to droplets for almost half a century, the fundamental phenomenon of the evaporation of sessile droplets is still a field that attracts a high level of interest due to its wide applicability and the development of new visualisation techniques or new types of complex fluids. This experimental study is focused two distinct aspects:- The evaporation of pure fluids has allow to study hydrothermal waves that appear in the droplets of volatile fluids during phase change. The influence of the type of fluid ---different alcohols and alkanes--- and the gravity levels ---Terrestrial, Lunar and Martian--- is investigated to have a better understanding of the flow motion inside droplet. Moreover, the use of different gravity levels allows to experimentally evidence the contribution of the atmospheric convective transport to sessile droplet evaporation. This investigation has allowed to develop an empirical model to take account of natural convection which greatly increases the evaporation rate in the quasi-steady diffusion-controlled evaporation model.- If complex fluids exhibit an evaporation dynamic similar to pure fluid, other mechanisms come into play, such as gelation, particles organisation and cracks formation. Wetting and different functional groups on the particles graphs will be studied in relation to the final pattern of cracks
Sartori, Paolo. "The Role of Interfaces in Microfluidic Systems: Oscillating Sessile Droplets and Confined Bacterial Suspensions." Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3423250.
Full textQuesta tesi di dottorato prende in esame il ruolo delle interfacce che caratterizzano i sistemi microfluidici, come ad esempio l’interfaccia libera aria/acqua delle gocce o l’interfaccia liquido/solido di fluidi racchiusi in microcanali. Questo lavoro ha un duplice carattere: da una parte, abbiamo studiato la dinamica di gocce sessili soggette ad oscillazioni del substrato; dall’altra, abbiamo investigato come la distribuzione spaziale della concentrazione in sospensioni batteriche, prese come sistema modello per colloidi attivi, venga alterata da un confinamento geometrico. Dinamica di gocce sessili. Il primo argomento rientra nel campo dei fenomeni di bagnabilità e della microfluidica aperta, che tratta il comportamento di gocce, tipicamente nel range dei nano- /microlitri, depositate su superfici aperte. A tali scale di lunghezza, questi sistemi sono dominati dalla capillarità a possono produrre effetti inaspettati che non vengono comunemente osservati alle scale macroscopiche a cui siamo abituati. I nostri studi sono volti al raggiungimento del controllo attivo del moto e della forma delle gocce per mezzo di vibrazioni del substrato, con applicazioni dalla Chimica alla Biologia. In particolare, è stato considerato il moto di gocce su in substrato inclinato sottoposto ad oscillazioni armoniche verticali. Normalmente, su superfici inclinate le goccioline rimangono ferme a causa dell’isteresi dell’angolo di contatto. Quando vengono applicate oscillazioni verticali le goccioline si sbloccano e scivolano giù. Sorprendentemente, per ampiezze di oscillazioni sufficientemente grandi le goccioline si muovono verso l’atro contro la forza di gravità. Un’analisi della risposta delle gocce al variare dell’accelerazione di picco e della frequenza di oscillazione, prendendo in esame fluidi con diverse tensioni superficiali e viscosità, ha permesso il controllo del moto unidimensionale lungo il pianoinclinato. Inoltre, abbiamo studiato le morfologie interfacciali di gocce d’acqua confinate sulla faccia superiore idrofilica di post rettangolari con larghezza 0.5 mm e varie lunghezze. Per piccoli volumi, il film liquido prende la forma di un filamento omogeneo con una cross-section uniforme simile ad un segmento circolare. Per volumi più grandi, l’interfaccia acqua/aria forma un rigonfiamento centrale, che cresce con il volume. Nel caso di post più lunghi di una lunghezza caratteristica, la transizione tra le due forme al variare del volume discontinua e mostra la bistabilità dei due stati morfologici associata ad un fenomeno di isteresi. Applicando al post, con volume d’acqua fissato corrispondente alla bistabilità, vibrazioni verticali con determinate frequenze si più indurre una transizione irreversibile dallo stato di filamento omogeneo a quello rigonfiato. Particelle auto-propulse sotto confinamento geometrico. Il secondo argomento riguarda il comportamento di fluidi attivi, cioè sospensioni di colloidi auto-propulsi che costituiscono sistemi intrinsecamente fuori equilibrio (Materia Attiva). In particolare, in presenza di strutture geometriche, tali sistemi si comportano in modo molto differente rispetto a colloidi Browniani all’equilibrio. Abbiamo analizzato il ruolo di diversi schemi di motilità sulla distribuzione di concentrazione di sospensioni batteriche confinate tra due pareti solide. considerando E. coli a P. aeruginosa wild-type, che si muovono secondo gli schemi Run and Tumble e Run and Reverse, rispettivamente. I profili di concentrazione sono tati ottenuti contando i batteri motili a diverse distanze dalle pareti. In accordo con studi precedenti, si osservato un accumulo di batteri motili in prossimit delle pareti. Sono state testate diverse frazioni di batteri motili e diverse distanze di separazione tra le pareti, nel range tra 100μm e 250 μm. I profili di concentrazione risultano indipendenti dalla distanza tra le pareti e dai differenti schemi di motilità e scalano con la frazione di batteri motili. Questi risultati sono confermati da simulazioni numeriche, basate su una collezione di particelle allungate auto-propulse che interagiscono solo tramite interazioni steriche.
Robson, Alyssa A. "Surface Tension Measurements of Various Surfactants Using the Constrained Sessile Drop Method." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1398819754.
Full textBahramian, Anohe. "Evaluating surface energy components of asphalt binders using Wilhelmy Plate and Sessile Drop Techniques." Thesis, KTH, Väg- och banteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-117463.
Full textHamuyuni, Joseph. "Measurement of surface tension in base metal sulphide mattes by an improved sessile drop method." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71651.
Full textAbusaksaka, Abdulgadir Ahmed. "Structuration et défauts de surface et de volume lors du séchage de suspensions colloïdales." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENI089/document.
Full textControlling the production of colloidal suspension films by evaporation is still, nowadays, atruly scientific obstacle for materials development. The drying of colloidal suspensions leads often tosurface and volume defects in the film. When the particles are soft, films are continuous but haveseveral folding surface defects. However, when the particles are hard (glassy latex, silica,...), the filmtends to crack and to be delaminated. These defects are often associated with residual stresses in thegel at the end of drying, due to the capillary pressure caused by the water menisci deformation at thefilm surface. Nevertheless, neither the size scale where constraint acts nor the relation between stressand cracking time were known.In this thesis we present the study of cracks morphology observed in films of differentcolloidal suspension mixtures obtained by a drying process. These mixtures are composed of hard(polystyrene crosslinked PBMA) and soft (PBA and PBMA) particles. The nanometric structure ofthese mixtures is obtained through neutron scattering and turbidity studies. We have mixtures withdifferent structures and different states of dispersion. While some mixtures contain dispersed particlesat a nanoscale, with an order of magnitude same as the particles size - 50 nm, some others containaggregated particles. The study of cracks morphology is performed on sessile drops by drying at thefree surface. Periodic radial cracks are observed during drying. We also observe that cracks periodincrease with the increment of soft particles fraction and temperature, but keeping constant itsperiodicity. We have demonstrated that the ratio: crack period between film thickness, i.e. λ/h, is theonly parameter that describes perfectly cracks morphology for a drying process at a free surface. Wealso demonstrated that this relation (λ/h) couldn’t decrease below 2 even in the case of glassy particles.Drying process induces high residual stresses in the gel, allowing to some fibers located between twocracks to delaminate radially. This delamination phenomenon fades with dissipation constraints. Wehave also established that the Russel’s mechanical model does not describe the period of cracks nearthe critical stress. Therefore, in this work we propose another model able to characterize theperiodicity of the cracks. We noticed that the properties of the substrate did not affect cracksmorphology. The evaporation rate changes the morphology of cracks, which in the case of a quickdrying it is possible to obtain unidirectional long loose fibers. However, for a slow drying, we arewitnessing the formation of not protruding cracks with the apparition of secondary transverse cracks
Singh, Sandeep. "Thermo-mechanical Behavior of Glass Based Seals for Solid Oxide Fuel Cells." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1288379341.
Full textMišáková, Liliana. "Měření povrchového napětí pro charakterizaci povrchů pokročilých keramických materiálů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-432866.
Full textJacquot, Francis. "Contributions expérimentale et théorique à une nouvelle approche de la mouillabilité." Vandoeuvre-les-Nancy, INPL, 1998. http://www.theses.fr/1998INPL056N.
Full textSobac, Benjamin. "Evaporation de gouttes sessiles : des fluides purs aux fluides complexes." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4801/document.
Full textThis thesis presents an experimental study on the evaporation of droplets on a solid substrate. In the first part we describe the evaporation of a liquid droplet, taking a particular interest in the influence of the substrate. The problem is approached from a new angle by ensuring that the various properties of the substrate, such as its roughness, surface energy and thermal properties, are controlled precisely. Thanks to this method it is possible to decouple the different influences of the substrate and to study evaporation in relation to various dynamics of triple lines and a wide range of contact angles, thermal conductivities and temperatures of the substrate. Experimental results are compared with the classic evaporation model, which considers evaporation as a process determined by the diffusion of vapor into the atmosphere. The study reveals the range of validity of this model and highlights the different additional mechanisms which may develop as well as their contribution. The use of an infrared camera reveals the development of a complex hydrodynamic non-axisymmetric pattern. The origin of this instability and its spatial and temporal dynamics are also explored. In the second part, the study is extended to the evaporation of a dropl of a biological suspension: human blood. As this fluid dries a complex pattern is formed which is dependent on the wettability of the substrate. Whereas a wetting situation leads to a ring-like deposit with radial cracks, a non-wetting situation reveals a complex shape composed of cracks and folds. The study focuses on the understanding of the physical mechanisms leading to these patterns and of the role of biology
DOEDENS, MARIEKEN. "How to take care of your rainwear, An evaluation of commercially available laundry and waterproofing agents and their effect on maintaining water-repellence." Thesis, Högskolan i Borås, Institutionen Textilhögskolan, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-17415.
Full textProgram: Textilingenjörsutbildningen
Nair, Sithara. "Novel Fluorous Hybrid Surface Modification Characterized by Wetting Dynamics, Morphology and Nanomechanics." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/446.
Full textDominguese, David J. "A Single Session of Repeated Wingate Anaerobic Test Caused Alterations in Peak Ground Reaction Force During Drop Landings." Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1268328477.
Full textRamos, Masana Ana. "Estudio de la reactividad a alta temperatura de aleaciones ligeras sobre recubrimientos cerámicos." Doctoral thesis, Universitat Ramon Llull, 2020. http://hdl.handle.net/10803/669953.
Full textLa interacción entre metales fundidos y las superficies de materiales cerámicos o metálicos es protagonista en diversos procesos de fabricación, tales como la inyección de aleaciones ligeras, la fundición de hierro o la síntesis de materiales compuestos metal-cerámicos (MMC, Metal Matrix Composites). Esta interacción se traduce en un fenómeno de mojado en mayor o menor medida de la superficie, hecho que puede modularse mediante la aplicación de tratamientos superficiales. El proceso de inyección de aleaciones de aluminio es probablemente uno de los procesos con metales fundidos con más impacto industrial. En el presente trabajo se han estudiado experimentalmente el proceso de mojado por Al9Si3Cu y aluminio puro fundidos de muestras de acero recubiertas utilizando el método de la gota yaciente en vacío en un equipo de ángulo de contacto diseñado y construido ex profeso para este proyecto. Por un lado se han ensayado recubrimientos de capa delgada depositados por la técnica MS-PVD (Magnetron Sputtering Physical Vapor Deposition) o HIPIMS-PVD (High Power Impulse Magnetron Sputtering) de TaN, TiB2, TiN, TiAlN, MoN y DLC(CrN). Por otro lado, se han utilizado recubrimientos gruesos depositados por HVOF (High Velocity Oxyfuel) de Cr3C2-NiCr y WC-CoCr. La evolución del ángulo y el radio de contacto se han estudiado mediante el registro de secuencias de imágenes y se han determinado las curvas de mojabilidad mediante el posterior tratamiento y análisis de imágenes. El mecanismo de mojado se ha determinado a partir de las curvas de mojabilidad y de la caracterización metalográfica de la superficie y de las secciones transversales que muestran la evolución de la interfase líquido-sólido y la formación de compuestos intermetálicos. Se discuten el efecto de la aleación, de la composición y morfología del recubrimiento y en la mojabilidad del sistema y se comparan los resultados obtenidos con la mojabilidad en sistemas no recubiertos. Los resultados muestran que los recubrimientos retardan la reacción entre el sustrato metálico y el aluminio fundido.
The interaction between molten metals and the surfaces of ceramic or metallic materials is the key in various manufacturing processes, such as the injection of light alloys, iron foundry or the synthesis of metal-ceramic composite materials (MMC, Metal Matrix Composites). This interaction translates into a phenomenon of wettability to a greater or lesser extent of the surface, which can be modulated by the application of surface treatments. The process of injection of aluminum alloys is probably one of the processes with molten metals with more industrial impact. In the present work, the wetting process for Al9Si3Cu and pure aluminum were analyzed experimentally with coated steel samples using the sessile drop method in vacuum in a contact angle device designed and constructed specifically for this project. On one hand, thin coating deposits deposited by the MS-PVD (Magnetron Sputtering Physical Vapor Deposition) or HiPIMS-PVD (High Power Impulse Magnetron Sputtering) of TaN, TiB2, TiN, (Ti,Al)N , MoN and DLC (CrN). On the other hand, thick coatings deposited by HVOF (High Velocity Oxyfuel) of Cr3C2-NiCr and WC-CoCr have been used. The evolution of the angle and the contact radius have been studied by recording sequences of images and the wettability curves have been determined through the subsequent treatment and image analysis. The wetting mechanism has been determined from the wettability curves and the metallographic characterization of the surface and the cross sections that show the evolution of the liquid-solid interface and the formation of intermetallic compounds. The effect of the alloy, the composition and morphology of the coating in the wetting behavior are discussed, and the results are compared to those obtained with uncoated system. The results show that coatings delay the reaction between the metal substrate and the molten aluminum.
Muhmood, Luckman. "Investigations of thermophysical properties of slags with focus on slag-metal interface." Doctoral thesis, KTH, Materialens processvetenskap, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-26611.
Full textQC 20101130
Горєлов, В. О. "Розробка удосконалених методик і приладу для вимірювання поверхневого натягу рідин і розчинів методом лежачої краплі." Thesis, Івано-Франківський національний технічний університет нафти і газу, 2003. http://elar.nung.edu.ua/handle/123456789/3981.
Full textДиссертация посвящена разработке методик измерения поверхностного натяжения жидкостей и растворов на границе раздела жидкость - окружающий газ воздух, разработке математического описания формирования лежащей капли жидкости в процессе измерения поверхностного натяжения, исследованиюю телевизионной системы измерения размеров лежащей капли, разработке прибора, реализующего предложенные методики -измерение поверхностного натяжения и разработке требований к нему, а также к методике использования результатов измерения поверхностного натяжения растворов поверхностно-активных веществ для технологических процессов интенсификации добычи нефти.
Dissertation is dedicated to research and development of surface tension measurement procedures at the boundary of contact of fluid and gas and the device, that realizes corresponding developed procedures. The known procedures of surface tension of fluids and solutions measurement by method of sessile drop are analyzed, their merits and demerits are determined. Surface tension measurement procedures of application are suggested. The process of sessile drop’s forming is analyzed and its mathematical description is given. The method of sessile drop parameters calculation is developed. These results are used for the development of surface tension measurement procedures. One of the developed procedures is based on calculation of two radiuses of curvature of a capillary surface for a point that belongs to the profile of a drop. Another assumes the measuring of the equatorial radius of a sessile drop and its square, limited by this radius and its top. The device for surface tension of fluids and solutions measurement has been developed, metrological analyses of famous and developed surface tension measurement procedures by method of sessile drop are conducted.
Lorrain, Vincent. "Influence des proprietes capillaires sur la corrosion du tungstene par des metaux liquides." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0099.
Full textCao, Weimin. "Theoretical and experimental studies of surface and interfacial phenomena involving steel surfaces." Doctoral thesis, KTH, Materialens processvetenskap, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-26194.
Full textQC 20101123
Landry, Karine. "Contribution à l'étude du mouillage réactif : étude du système aluminium/carbone." Grenoble INPG, 1995. http://www.theses.fr/1995INPG0043.
Full textDallel, Dorra. "Etude expérimentale modèle de l'imbibition capillaire de substrats poreux à volume et structure de pores ajustables." Phd thesis, Université de Haute Alsace - Mulhouse, 2012. http://tel.archives-ouvertes.fr/tel-00870951.
Full textCook, Grant O. III. "Joining Polycrystalline Cubic Boron Nitride and Tungsten Carbide by Partial Transient Liquid Phase Bonding." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2366.
Full textShyam, Sunder *. "Dynamics of Bubbles and Drops in the Presence of an Electric Field." Thesis, 2015. http://etd.iisc.ernet.in/2005/3833.
Full textLiu, Jung-Yu, and 劉鎔瑜. "Solidification of Resonating Sessile Drop." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/ygm3j4.
Full text國立臺灣大學
機械工程學研究所
107
This research is trying to find out the influence of the acceleration and the frequency of a sessile resonating drop. Also, this research is trying to maintain the resonance shape of the drop by using cold fluid to freeze it. The experimental fluid is gallium. We used aLED halo as the lighting method. From the reflection of the halo on the surface of the drop, we could tell the shape of the resonating drop. In this research, we found 16 modes which had been found before, including 7 sectoral modes, 4 zonal modes and 5 tesseral modes. In addition to these 16 modes, we also found several unstable sectoral modes which don’t have the same amplitude in every crest, and 3 jumping modes with different polygon shapes. We found the relation between the frequency and the amplitude. The experiment result shows that the force thresholds of sectoral modes are independent of the volume of the drop. In other words, if the volume of the resonating drop increases, the minimum force to trigger the specific sectoral mode will still be the same. We found that the shape of the solidification drop depends on fluid and the wave amplitude, not the resonance mode. Additionally, the experiment and the calculation results show that it’s impossible to maintain the resonance shape by using solidification.
Shrikanth, V. "A Non Resonant Piezoelectric Sensor for Mass, Force and Stiffness Measurements." Thesis, 2015. http://etd.iisc.ernet.in/2005/4000.
Full textChuang, Yu-Chen, and 莊于真. "Sessile Drop Evaporation and Wetting Phenomena on Patterned Surfaces." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/01139451371467471875.
Full text國立臺灣大學
化學工程學研究所
101
There are two topics discussed in this study: water evaporation on soft patterned surfaces and the observation of the Cassie impregnating wetting state. First, we demonstrate the evaporation mechanism of water sessile drop on different softness of fixed patterned PDMS (polydimethylsiloxane) substrate and also compare the results from the viewing angle of 0° with that from the viewing angle of 45°. The evaporation mechanism generally starts from the constant contact radius mode and turns into constant contact angle mode when the receding contact angle is reached. The softer the substrate is, the smaller the receding contact angle is. The wetting transition from the Cassie to the Wenzel state is also observed after the constant contact angle mode and the softer substrate will induce an earlier wetting transition due to the softer texture. By comparing the theoretical calculation of evaporation rate in different modes, we can examine whether the expected evaporation mechanism is suitable or not. Second, the Cassie impregnating wetting state is investigated by placing the ethanol drop on different patterned PDMS surfaces. Due to the lack of the knowledge of the Cassie impregnating state, our main purpose is to find out the relationship between the structure of the surfaces and the impregnating region. It is observed that the rougher the substrate is, the larger the impregnating region is. However, so far we cannot specify this phenomenon and its impregnating region. Our preliminary inference is that the Cassie impregnating wetting state is only the metastable state passing to complete wetting and the metastable state is the result of the equilibrium of the imbibition rate and the evaporation rate of ethanol. Besides, the contact angle in the Cassie impregnating wetting state is also examined to see if the Cassie equation can describe and the study of the ethanol drop evaporation on patterned surface is discussed to further understand the Cassie impregnating wetting state.
Lai, Ting-Yin, and 賴亭吟. "Contact Angle Measurement from analysis of Sessile Drop Shapes." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/25754377237830749116.
Full text國立中正大學
化學工程所
95
In contact angle measurement from analysis of sessile drop shapes, the quality of drop images and the analysis of drop shapes determine accuracy of the contact angle. High quality drop images should have large contrast in brightness at the edges. We improved the image quality by adjusting the elements of the homemade contact angle goniometer, and found a better technique for contact angle measurement. Then we determined the drop edges consistant with the real image by gradient method and analyzed the drop shape by circle fitting. Contact angle can be obtained from the slope at the solid-liquid-vapor contact point. The adsorption mechanism of aliphatic dithiocarboxylic acid (ADTCA), CH3(CH2)nCS2H (n=13,14) self-assembled monolayers(SAMs) onto the gold surfaces can be studied by advancing contact angle. The trend of advancing contact angle of these SAMs with two different chain length during the formation process are opposite. This can be attributed to the odd-even effect.
ELDER, JAMES EDWARD. "INTERFACIAL TENSION MEASUREMENT BY SESSILE DROP USING DIGITAL IMAGE PROCESSING." Thesis, 1987. http://hdl.handle.net/1911/13216.
Full textGitiafroz, Roya. "Study of surface tension of pulmonary surfactant using a constrained sessile drop technique." 2005. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=370093&T=F.
Full textYan, Shi-Liang, and 顏世良. "Effects of Contact Line Retraction Velocity to Receding Contact Angle by Sessile Drop Method." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/52329205883811419530.
Full text國立臺灣科技大學
化學工程系
104
This experiment shows the influence of triple line retraction velocity on receding contact angle by using sessile drop method. The experiment was performed by dropping the liquid drops on polymer PMMA (polymethyl methacrylate) and PC (poly carbonate) substrates. The suction process was then performed to reduce the droplet volume by pumping out the liquid drop using syringe pump and needle. It was found that the contact angle change when the de-wetting velocity increase. From the experimental results, we can observe there are three stages: constant contact radius (CCR mode), constant contact angle, (CCA mode) and the mixing stage (mixed mode). In CCR stage the wetting diameter is constant but contact angle continue to decline, when the CCA stage the contact angle is nearly constant but wetting diameter decrease. Finally, both contact angle and wetting diameter are continue to decline and retreat constantly, we call this stage is mix stage. From this experiment, we observe that in CCA stage, the greater retraction velocity will resulting smaller contact angle. The comparison between the experimental data and the theoretical models obtained from literatures was performed to verified our conclusion that the receding contact angle is caused by the interaction between liquid molecules and substrates or viscous dissipation.
Lin, Chia-Hui, and 林佳慧. "A Study on the Adsorption Kinetics of Ionic Surfactants and Evaporation Behavior of Sessile Drop." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/00295750801500237472.
Full text國立臺灣科技大學
化學工程系
102
The dynamic and equilibrium surface tensions for the adsorption of anionic surfactant AOT and cationic surfactant DDA in aqueous solutions onto a clean air-water interface was measured by using a video-enhanced pendant bubble tensionmeter. A comparison between the nonionic and ionic models (Langmuir, Frumkin and generalized Frumkin models) and the equilibrium and dynamic surface tensions of AOT and DDA were performed in order to study the adsorption mechanism and to determine the diffusivity of surfactant molecules. The adsoprion kinetics for AOT in aqueous 500 mM NaCl solution was found to be diffusion controlled with a diffusivity of (1.55±0.3)×10-6 cm2/s. A plateau region was observed at dynamic surface tension profile of DDA aqueous solution at γ = 43.7 mN/m at 25oC. The existence of a plateau implied the existence of a liquid expanded and liquid condensed phase transition for the DDA molecules adsorbed at air-water interface. In the second part of this study, polycarbonate (PC) substrates with various surface roughness were used on the investigation of the evaporation process in a circumstance of fixed humidity. Relaxation of contact angle was monitored and the pinning phenomenon was studied. The definition of receding contact angle was also discussed at the end of this work.
Pan, Sih-Ting, and 潘姒婷. "Study of Mirror-Electrowetting-on-Dielectric by the Sessile Drop Method for Applications of Parallel Droplets Manipulation." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/81741481851864408886.
Full text國立交通大學
奈米科技研究所
97
EWOD (Electrowetting-on-dielectric) is a method to change the surface wettability on top of an electrode. This phenomenon is reversible and consumes very low power. MEWOD (Mirror-EWOD) is occurred when we replace solid electrode with liquid electrode, and the size of the liquid electrode is shrunk to a comparable volume of the upper droplet. Electrowetting was found on both sides of the dielectric film and the mirror-EWOD force would bring the overlapped droplets to each other. In this thesis, we analyze the phenomenon of MEWOD and put the device into silicone oil to reduce the problem of vibration and evaporation. Finally, we integrate EWOD and MEWOD to manipulate parallel droplets. When applying a voltage, two stacked droplets can be actuated concurrently. By increasing the number of the dielectric sheet, the concept would be expanded to manipulate more than two droplets without increasing the complicity of the device fabrication and the electric circuit.
Chao, Kuo-Lin, and 趙國霖. "Surface Tension Measurement of Liquid Fe-Si-B and Fe-16Cr-2Co-Mn-Mo-N alloys by Sessile Drop method." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/63320841903274992153.
Full text國立臺灣大學
材料科學與工程學研究所
102
The purpose of this study is to investigate the high temperature contact angle and surface tension under various components of the refractories for Fe-Si-B alloys and Fe-16Cr-2Co-Mn-Mo-N high nitrogen stainless steels. The high temperature contact angle and surface tension are measured by Sessile Drop Method in this study. According to Bashforth and Adams equation, the accurate measurement of the contour droplet size and density will affect the measurement results of its surface tension. The surface tension of pure silver is measured and compare with literatures, the measured result is based for measurement calibration. This research can be discussed and divided into three parts: (1) The surface tension results under various refractories and surface roughness condition for Fe-Si-B alloys. (2) Thermodynamics data and Butler equation is calculated the surface tension of Fe-Si-B ternary alloys. (3) The surface tension of Fe-16Cr-2Co-Mn-Mo-N high nitrogen stainless steels on single high alumina contents refractory. The experimental results are shown the surface tension and contact angle of Fe-Si-B alloys and Fe-16Cr-2Co-Mn-Mo-N high nitrogen stainless steels decreases as temperature increases. The surface tension of Fe-Si-B alloys is not different with various refractories compositions and roughness. Only contact angle and wetting behavior variable and depends on various refractories compositions and roughness. The contact angle measurement results are shown that the refractories with the silicon-nitrogen-containing components have the highest contact angles, the refractories with single alumina or silica containing components have the lowest contact angles. The refractories with composite alumina - silica contacting have middle contact angles in between silicon-nitrogen-containing refractories and single alumina or silica containing refractories. The experimental results also showed that the contact angle increases as roughness increases. The thermodynamics data and Butler equation calculation surface tension results is close to measurement values when the metal is melted fully near liquid temperature. However, as the temperature increases, the thermodynamic surface tension calculation result is not close to experimental measured value, the reason might be interfacial chemical reaction and blurred solid-liquid-vapor triple interface line caused volume measured error at high temperature. Furthermore, increasing boron and carbon contents will decrease the surface tension of Fe-Si-B alloys. Increasing manganese and nitrogen contents will decrease the surface tension and contact angle of the Fe-16Cr-2Co-Mn-Mo-N high nitrogen stainless steels. The contact angle and surface tension measurement results are shown that the Fe-16Cr-2Co-Mn-Mo-N high nitrogen stainless steels with the lowest manganese and nitrogen containing components have the highest contact angle and surface tension.
Lin, Chen-Han, and 林承翰. "A study of motions of a sessile water drop on a switchable surface via liquid crystal molecular orientations under influence of morphologies." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/3xvu33.
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