Surface Tension Driven Flow

Рассмотрено взаимосвязь геометрических параметров дисков лущильника с их скоростью вращения и параметрами ориентации в пространстве. Определены размеры и форма почвен-ного пласта, отделяемого диском лущильника. Приведен расчет силовых реакций почвы на сферическую поверхность диска. При решении задач устойчивости движения лущильника учтены диссипативные потери энергии, а также применены методы Ляпунова и разложение системы уравнений в ряд Тейлора. Теоретические исследования проверены эксперименталь-но. В процессе полевых экспериментов изучено влияние параметров лущильника на параметры качества обработки почвы, урожайность возделываемой культуры и технико-экономические показатели.

Retrogradation rate and extent were determined by differential scanning calorimetry and rheology measurements on 40% dry matter gels made from pea, modified waxy maize, rice, waxy rice, wheat, manioc, potato and microwaved irradiated potato starches. As a result, each starch retrogrades differently, depending also on the measurement technique. Nevertheless, potato and pea starches seem to be the most sensitive and the waxy and modified waxy types are the least sensitive to retrogradation. ~ ~~ Retrogradationskinetik von acht Starken. Retrogradationsgeschwindigkeit und -ausmaR wurden mittels Differential-Rastercalorimetrie und rheologischen Messungen an Gelen mit 40% TS aus Erbsen-, modifizierter Wachsmais-, Reis-, Wachsreis-, Weizen-, Maniok-, Kartoffel-und mikrowellenbestrahlter Kartoffelstarke bestimmt. Es zeigte sich, daR alle Starken unterschiedlich retrogradieren, auch in Abhangigkeit von der MeBtechnik. Trotzdem scheinen Kartoffel-und Erbsenstarken die empfindlichsten und die wachsigen und modifizierten wachsigen Arten die am wenigsten empfindlichen Starken gegeniiber der Retrogradation zu sein. ~ starctdstarke 42 (1990) Nr. 3. S . 99-101 0 VCH Verlagsgesellschaft mbH, D-6940 Welnheim. 1990 0038-9056/90/0303-09$02.50/0

Introduction: Rain brings copious water to us, which is essential for all (humans, flora and fauna). Rain drops is a collection of drops of size about mm. drops coalesce from tiny drops. The formation of droplets is intimately connected with surface tension, curvature and saturated vapor pressure. When we say vapor pressure (vp) and saturated vapor pressure (svp), we mean the pressure and svp in equilibrium over a plane surface of its liquid. For example, svp of vapor of water is 760 mm of mercury at 100 deg C, it is implied that at 100 deg C, the svp of water vapor in equilibrium over a plane surface of (boiling) water is 760mm of mercury. At this temperature the super incumbent pressure (atmospheric pressure) is also 760 mm of mercury. At 30 deg C, the svp is 31.5 mm of mercury. A liquid boils at a temperature when its svp is equal to the incumbent pressure. However the svp of vapor with its liquid phase which has a curvature is different from svp in contact with a plane surface. This discussion is important as this is intimately related to cloud formation, conditions for growth of drops and other meteorological phenomena.

In this study, a novel fructose-based DES of choline chloride (2-hydroxyethyl-trimethylammonium) has been synthesized at different molar ratios. The physical properties such as density, viscosity, surface tension, refractive index and pH were measured and analyzed as function of various temperatures (25-85 • C). The analysis of these physical properties revealed that these new DESs have the potential to be utilized for possible industrial applications involving processing and separation of food constituents. The suggested DESs have many desirable characteristics, e.g. they have low vapor pressure, inflammable, biodegradable, and made from renewable resources. The use of these DESs will positively affect the environment and make use of available renewable resources.

Flow patterns created by liquid jets impinging at angles off horizontal are studied. Little effect of gravity and contact angle at flow rates studied. Width and height of radial impingement region are predicted by the model. Falling film width is correlated with film jump radius. Formation of dry patches in falling film is predicted by the model.

Surface tension is one of the important deep eutectic solvents (DESs) physical properties which provides considerable information related to the molecular influence on the intensity of interactions in the mixture. Due to the absence of DESs surface tension experimental data, prediction methods of this property become of high importance. In this work, two simple methods for the prediction of DESs surface tension are presented. The first method reports the use of the parachor to predict surface tension. In the second method, the effect of temperature variation on surface tension was predicted using the Othmer equation. The parachor of nine different DESs based on ammonium and phosphunium salts were determined experimentally as well as calculated from the molecular structure of their constituting components using available parachor contribution data for neutral compounds. The results showed that calculated and experimental parachor of DESs were notably close and that the parachor contribution data developed for neutral compounds can be successfully utilized for deep eutectic solvents with an average surface tension prediction percentage error of 6.4%. The average prediction percentage error using the Othmer equation was 2.57%. This proves that surface tension of DESs can be predicted efficiently using either one of the two suggested methods.

We present a simple bench-top technique to produce centimeter long concentration gradients in biomaterials incorporating soluble, material, and particle gradients. By patterning hydrophilic regions on a substrate, a stripe of prepolymer solution is held in place on a glass slide by a hydrophobic boundary. Adding a droplet to one end of this “pre-wet” stripe causes a rapid capillary flow that spreads the droplet along the stripe to generate a gradient in the relative concentrations of the droplet and pre-wet solutions. The gradient length and shape are controlled by the pre-wet and droplet volumes, stripe thickness, fluid viscosity and surface tension. Gradient biomaterials are produced by crosslinking gradients of prepolymer solutions. Demonstrated examples include a concentration gradient of cells encapsulated in three dimensions (3D) within a homogeneous biopolymer and a constant concentration of cells encapsulated in 3D within a biomaterial gradient exhibiting a gradient in cell spreading. The technique employs coated glass slides that may be purchased or custom made from tape and hydrophobic spray. The approach is accessible to virtually any researcher or student and should dramatically reduce the time required to synthesize a wide range of gradient biomaterials. Moreover, since the technique employs passive mechanisms it is ideal for remote or resource poor settings.

In this study, a novel fructose-based DES of choline chloride (2-hydroxyethyl-trimethylammonium) has been synthesized at different molar ratios. The physical properties such as density, viscosity, surface tension, refractive index and pH were measured and analyzed as function of various temperatures (25-85 • C). The analysis of these physical properties revealed that these new DESs have the potential to be utilized for possible industrial applications involving processing and separation of food constituents. The suggested DESs have many desirable characteristics, e.g. they have low vapor pressure, inflammable, biodegradable, and made from renewable resources. The use of these DESs will positively affect the environment and make use of available renewable resources.

Deep eutectic solvents (DESs) are considered nowadays as green ionic liquid (IL) analogues. Despite their relatively short period of introduction as a special class of ILs, they have been under an increasing emphasis by the scientific community due to their favorable properties. In the present study, a glucose based DES of choline chloride (2-hydroxyethyl-trimethylammonium chloride) with the monosaccharide sugar d-glucose anhydrous was synthesized at different molar ratios. The physical properties of density, viscosity, surface tension, refractive index, and pH were measured and analyzed as function of temperature in the practical temperature range of 298.15-358.15 K. The analysis of these physical properties revealed that these novel DESs have the potential to be utilized for several possible industrial applications involving processing and separation of food constituents, pharmaceutical applications, as well as mediums for chemical reactions. © 2012 Elsevier B.V.

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A numerical method for solving Navier-Stokes equations and combined with a phase-field interface model is applied to flow problems of motion of an incompressible isothermal two-phase fluid with a high density ratio on a solid surface. Based on the free-energy theory, a fluid interface is described as a finite volumetric zone across which the physical properties vary continuously. The wettability of a solid surface is taken into account through a simple boundary condition derived from the increase in free energy on the surface. The phase-field approach simplifies the capture of motions of a fluid interface on a surface (contact line). The major findings from the simulations are as follows: (1) the contact-line motions of the liquid column under gravity are well predicted in comparison with the available data; (2) the static contact angle is flexibly controlled by a parameter of the wetting potential of the surface; (3) the capillary force is evaluated appropriately; (4) the acceleration of the two-phase flow in a channel with a local hydrophilic surface is predicted and observed to be in qualitative agreement with the experimental data; and (5) the displacement and breakup of a single drop on a flat solid wall are well predicted qualitatively. These results prove that the phase-field method can be employed for simulating air-water flows on a surface with heterogeneous wettability.

Capillary driven surface oscillations of liquid argon (Tsat = 87.3 K at 1,013 hPa) have been investigated in a partly filled right circular cylinder under non-isothermal boundary conditions. The oscillations take place during the reorientation from the normal gravity surface position towards a new position upon step reduction of gravity. The situation is similar to the end of thrust in a rocket tank when the cold propellant moves along the warmer tank wall driven by capillary forces. The aim was to investigate the influence of the temperature difference between the slightly subcooled cryogenic liquid and the superheated cylinder wall on the oscillations and their characteristics in a single-component, two-phase system. Axial wall temperature gradients of averaged 0.15 K/mm − 1.93 K/mm above the normal gravity surface position were implemented. A general dependence of the reorientation behavior on the gradient value was observed, concerning the apparent contact line behavior, the frequency and damping of the oscillations of the free surface center point, and the apparent contact angle. The behavior of the ullage pressure was found to follow the behavior of the contact line.

We present a simple bench-top technique to produce centimeter long concentration gradients in biomaterials incorporating soluble, material, and particle gradients. By patterning hydrophilic regions on a substrate, a stripe of prepolymer solution is held in place on a glass slide by a hydrophobic boundary. Adding a droplet to one end of this "pre-wet" stripe causes a rapid capillary flow that spreads the droplet along the stripe to generate a gradient in the relative concentrations of the droplet and pre-wet solutions. The gradient length and shape are controlled by the pre-wet and droplet volumes, stripe thickness, fluid viscosity and surface tension. Gradient biomaterials are produced by crosslinking gradients of prepolymer solutions. Demonstrated examples include a concentration gradient of cells encapsulated in three dimensions (3D) within a homogeneous biopolymer and a constant concentration of cells encapsulated in 3D within a biomaterial gradient exhibiting a gradient in cell spreading. The technique employs coated glass slides that may be purchased or custom made from tape and hydrophobic spray. The approach is accessible to virtually any researcher or student and should dramatically reduce the time required to synthesize a wide range of gradient biomaterials. Moreover, since the technique employs passive mechanisms it is ideal for remote or resource poor settings.

"Nanofluids", smart fluids with advanced thermal properties, have proved their promising potential in enhancing the heat transfer performance of a thermal system as well as mitigating the energy crisis of the universe. Besides all other's thermo-physical properties, surface tension governs the transport of the liquid and plays a crucial role in the heat transfer. However, the studies on the effect of surface tension on the performance of nanofluids are quite a few and demonstrated debatable results. Therefore, the present experimental study attempts to determine the surface tension of the nanofluids by dispersing Al2O3, TiO2, and SiO2 nanoparticles in Distilled Water (DW). The experiment was conducted by using the most common Du-Hotly ring method in DCAT11EC automatic surface tensiometer. In this study, the authors analyzed all the possible effects on surface tension of nanofluids with the change in concentrations (from 0.05 to 025 vol.%) and temperatures (from 30 degrees C to 50 degrees C), as well as the impact of various nanoparticles along with their sizes. The results indicate that the surface tension of the nanofluids increases with concentration, whereas decreases with the increase in temperature. Besides, the smaller nanoparticles exhibit lower surface tension than the larger ones. All in all, the surface tension of the nanofluids augments from 3.1% to 7.8% in compared with the base fluid for concentrations of 0.05 vol.% to 0.25 vol.% and temperatures of 30 degrees C to 50 degrees C, in all cases. (C) 2015 Elsevier Ltd. All rights reserved.

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Intrinsic viscosities [η] for 0.2, 0.4, 0.6, and 0.8 mg% aqueous of each Bovine serum albumin
(BSA) and egg albumin (EA) solutions under zero, 0.5 and 0.7 magnetic flux at 298.15 K and
1 atmosphere are reported. The [η] data for BSA are higher than EA and values of both
increase with magnetic flux strengthening molecular interactions.

In this study, a novel fructose-based DES of choline chloride (2-hydroxyethyl-trimethylammonium) has been synthesized at different molar ratios. The physical properties such as density, viscosity, surface tension, refractive index and pH were measured and analyzed as function of various temperatures (25-85°C). The analysis of these physical properties revealed that these new DESs have the potential to be utilized for possible industrial applications involving processing and separation of food constituents. The suggested DESs have many desirable characteristics, e.g. they have low vapor pressure, inflammable, biodegradable, and made from renewable resources. The use of these DESs will positively affect the environment and make use of available renewable resources. © 2012 Elsevier B.V. All rights

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Material, chemical and biological gradients have found widespread use in biotechnology and materials science for applications such as diagnostics, fundamental studies on biological processes, and material screening. [ 1 ] A host of techniques, generally involving microfl uidic devices and auxiliary apparatus, exist to create chemical and material gradients

We consider here the effects of inertia on the instability of a flat liquid film under the effects of capillary and intermolecular forces (van der Waals interaction). Firstly, we perform a linear stability analysis within the long-wave approximation, which shows that the inclusion of inertia does not produce new regions of instability other than the one previously known from the usual lubrication case. The wavelength,${\it\lambda}_{m}$, corresponding to the maximum growth,${\it\omega}_{m}$and the critical (marginal) wavelength do not change. The most affected feature of the instability under an increase of the Laplace number is the noticeable decrease of the growth rates of the unstable modes. In order to put in evidence the effects of the bidimensional aspects of the flow (neglected in the long-wave approximation), we also calculate the dispersion relation of the instability from the linearized version of the complete Navier–Stokes (N–S) equations. Unlike the long-wave approximatio...

This technical note describes a new bench-top method for producing anisotropic hydrogels composed of gradient layers of soluble factors, particles, polymer concentrations or material properties. Each gradient layer was produced by a previous gradient method in which a droplet of one precursor solution was added to a thin layer of a second solution. The ensuing rapid capillary flow along the open channel generated a gradient precursor solution, which was then crosslinked to form a gradient gel. Repeating these steps allowed a layered gel to be iteratively constructed with as many gradient layers as desired. This technique renders the synthesis of multi-layered gradient gels accessible to virtually any researcher and should help simplify the production of more biologically relevant cellular microenvironments.

A simple and inexpensive method is presented employing passive mechanisms to generate centimeters-long gradients of molecules and particles in under a second with only a coated glass slide and a micropipette. A drop of solution is pipetted onto a fluid stripe held in place on a glass slide by a hydrophobic boundary. The resulting difference in curvature pressure drives the flow and creates a concentration gradient by convection. Experiments and theoretical models characterize the flows and gradient profiles and their dependence on the fluid volumes, properties, and stripe geometry. A bench-top rapid prototyping method is outlined to allow the user to design and fabricate the coated slides using only tape and hydrophobic spray. The rapid prototyping method is compatible with microwell arrays, allowing soluble gradients to be applied to cells in shear-protected microwells. The method’s simplicity makes it accessible to virtually any researcher or student and its use of passive mechanisms makes it ideal for field use and compatible with point-of-care and global health initiatives.

Surface tension is one of the important deep eutectic solvents (DESs) physical properties which provides considerable information related to the molecular influence on the intensity of interactions in the mixture. Due to the absence of DESs surface tension experimental data, prediction methods of this property become of high importance. In this work, two simple methods for the prediction of DESs surface tension are presented. The first method reports the use of the parachor to predict surface tension. In the second method, the effect of temperature variation on surface tension was predicted using the Othmer equation. The parachor of nine different DESs based on ammonium and phosphunium salts were determined experimentally as well as calculated from the molecular structure of their constituting components using available parachor contribution data for neutral compounds. The results showed that calculated and experimental parachor of DESs were notably close and that the parachor contribution data developed for neutral compounds can be successfully utilized for deep eutectic solvents with an average surface tension prediction percentage error of 6.4%. The average prediction percentage error using the Othmer equation was 2.57%. This proves that surface tension of DESs can be predicted efficiently using either one of the two suggested methods. © 2012 Elsevier B.V.

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