Drop Shape Research Articles

Sex Chromatin in New Hampshire Cocks

Sex chromatin (SC) is defined as inactive X chromosome in the female somatic cells, it condensed as heterochromatic at interphase of the nucleus and appears like nuclear satellite projection, and only female cells contain SC in mammals. Different ages of cocks: immature (8,16 weeks old), growing (24 weeks old) and production age (32,48 weeks old) , were studied to detect the sex chromatin (SC) with it's various shapes :Sessile nodule(SS), Drum stick(DS), Tear drop(TD) and Club shape(CS) in the blood lymphocytes of blood smears prepared from WBCs of 45 New Hampshire(NH) strain cocks. Also SC measurements were detected which include: vertical (V) and horizontal (H) axes, SC area (SCA), nuclear area (NA), and the ratio(R) between these two areas. . Results show that SC is present in the male chicken blood lymphocytes in all ages. There is no significant difference in the incidence of the SC or its various measurements between ages, but the vertical axis was recorded a significant (P

Numerical study of two equal-sized miscible drops undergoing head-on collision

The numerical analysis focuses on investigating head-on collisions between two miscible drops composed of distinct fluids, specifically ethanol and water. The simulations are performed using a coupled level set and volume of fluid approach with different Weber numbers to study the effect of drop inertia. The code is validated against experimental and numerical results from earlier investigations. Additionally, a comparative study involving both water drops and ethanol–water drops is conducted to explore the impact of varying surface tension ratios on collision outcomes. Results show that when miscible drops collide, the merged liquid drop exhibits asymmetric behavior, such as an asymmetric combined drop shape in cases of permanent coalescence or an asymmetric end droplet breakup in cases of reflexive separation. The collision outcome undergoes significant variation as the Weber number changes. At lower Weber numbers, permanent coalescence is observed, while at medium Weber numbers, reflexive separation occurs without the formation of a secondary drop. For medium to large Weber numbers, reflexive separation with the generation of one secondary drop becomes prominent, and in the case of very large Weber numbers, multiple satellite drops form. The maximum vertical elongation of the merged drop and corresponding surface energy increase as the surface tension ratio rises, irrespective of the Weber number. However, for a fixed surface tension ratio, the maximum vertical elongation and associated surface energy vary with an increase in the Weber number. The findings also shed light on the enhanced internal mixing arising from the mismatched surface tension of the colliding drops as the Weber number increases. Furthermore, the study explores the effect of drop inertia on various aspects, including asymmetric collision behavior, energy budget, and mixing index.

Role of surface charge convection on oblate droplets in different conductivity regimes

This paper presents a robust numerical model to simulate the electro-hydrodynamic flows of a neutrally buoyant liquid droplet suspending in another liquid for varying electrical conductivities ranging from near-dielectric to highly conductive fluids. The effect of such conductivity on the interfacial charge transport in the droplets has been investigated. The model is first validated with the theory of electro-rotation corresponding to the strong electric field. The results are compared with the theoretical predictions from the Quincke theory. The angular velocities at different electric field ratios agree well with theoretical predictions. Furthermore, droplet investigations are performed in distinct conductivity regimes with the electric Reynolds number ranging from 10−2 to 104. The findings reveal that conductivity influences the evolution of diverse droplet shapes in the corresponding regimes through surface charge convection. We observe prolate shapes at very low electric conductivities, while larger conductivities of droplets and suspending media lead to oblate drop shapes. With increasing electrical conductivity of the droplet and the medium, we observe the onset of distinct droplet shapes similar to the existing literature. The mechanism for the onset of different regimes is adequately explained by quantifying surface properties like tangential stress and velocity.

Splashing impact of a falling liquid drop

The splashing phenomenon associated with the impact of a liquid drop on a liquid pool is investigated in this study using the volume of fluid method. The different outcomes of this phenomena largely depend on the height (/depth) of a liquid pool and the impinging drop velocity. The impingement angle, drop shape, fluid properties, and other non-isothermal effects also play a role, but we have eliminated those dependencies by considering no variation in these parameters. The different phenomena that are observed when a drop impacts a liquid pool are controlled by (i) crater depth and wave-swell (rim of the crater) expansion, (ii) wave-swell retraction followed by crater side retraction, and (iii) crater base retraction. During splashing, a deep crater is produced in the receiving liquid after the drop impact. At its rim, a crown-like cylindrical liquid film is ejected out of the crater. Small droplets are normally shed from this rim. It is seen that the depth of the pool has dramatic effects on the dynamics of the crown formed during splashing. When observed even more comprehensively, the physical attributes of the crown, such as crown height and crown radius, are found to strongly relate to the velocity of the falling drop. Finally, we try to demarcate the regions of splashing with and without the formation of secondary droplets on the regime map of Weber number–dimensionless pool depth.

Position dependence of the standing-wave radiation pressure quadrupole projection on a sphere applied to drop shape.

There have been decades of interest in using the ultrasonic radiation pressure of standing waves to deform nearly spherical objects. An analytical approach sometimes associated with the present author involves approximating projections of the radiation pressure on spheres small in comparison with the wavelength and calculating the response to that projection. In 1981, for small fluid spheres, some terms in the quadrupole projection were published along with the dependence on the size and location of the sphere. An associated application was the flattening of levitated drops in air which are attracted toward velocity antinodes of a standing wave having horizontal equiphase surfaces. In subsequent applications of those results, the predicted analytical dependence on the location of the drop is frequently neglected. For the case of small weakly deformed drops in air in normal gravity, that omission is shown to result in an overestimation of the deformation and of the magnitude of the quadrupole radiation pressure projection. The present discussion simplifies the early results when applied to oblate drops and illustrates the consequence of including the position dependence on the modified small deformation. For large trapped oblate bubbles in water (also reviewed), the shape and location depend on the size.

Quantitative experimental study on the apparent contact angle of unsaturated loess and its application in soil–water characteristics curve modeling

AbstractAdvancing and receding water contact angles, often denoted as the maximum and minimum apparent water contact angles, are crucial parameters reflecting a soil's water holding capacity. These parameters play an important role in establishing theoretical soil–water characteristic curves (SWCCs) for unsaturated soils. However, pre‐assuming constant advancing and receding contact angles during soil wetting and drying processes may be erroneous due to their close correlations with the water content and void ratio. To address this research gap, systematic laboratory measurements were conducted on a loess with different void ratios and water contents. Apparent water contact angles were acquired using an axisymmetric drop shape analyzer, enabling a comprehensive dataset. Analysis of variance was employed to assess the statistically significant differences between void ratios and water contents. The results reveal a significant increase in the observed water contact angle as the void ratio decreases and a decrease with increasing water content. Although both the void ratio and water content influence the water contact angle, the latter has a more pronounced effect. The relationship between the receding water contact angle and water content/void ratio is observed to be linear. The identification of this linear relationship offers insights into the fitting of the SWCC for loess across varying void ratios. This study serves to enhance theoretical methodologies, particularly in the adaptation of contact angles, thus facilitating the development of more precise SWCC models.

Characterization of nanoceria-modified silicone soft liners: Surface morphology, hardness, wettability, cytotoxicity, and antifungal properties in artificial saliva – An in vitro study

Statement of problemSoft liners are essential for denture wearers, which aids in the healing of soft tissue injuries caused by rough denture base surfaces. Silicone soft liners, while effective, can accumulate biofilm over time, necessitating enhancement. PurposeThis in vitro study aimed to assess the efficacy of silicone soft liners incorporating varying concentrations of cerium oxide nanoparticles. Materials and methodsA stainless-steel die as per ISO standard 10139-2-2018 (35 × 6 mm), Using G*Power 3.0.10 software, 400 samples were prepared with 95 % confidence interval and 80 % power. Samples were divided into five groups: surface morphology (Group A), surface hardness (Group B), wettability (Group C), cytotoxicity (Group D), and antifungal property (Group E). Each group was subdivided based on cerium oxide nanoparticle concentrations. Samples were stored in artificial saliva until evaluation. Surface morphology was examined via scanning electron microscopy (SEM), surface hardness using Shore A Durometer, wettability by drop shape analysis, cytotoxicity via MTT assay, and antifungal properties using crystal violet staining.Data were assessed for normal distribution using Kolmogorov-Smirnov and Shapiro-Wilk tests. ResultsSEM analysis showed optimal nanoparticle dispersion in Group A2(0.25 %) and A3 (0.5 %). Group B2 (0.25 %) exhibited the lowest mean surface hardness, decreasing from day 1 to day 30. Group C3 demonstrated the most hydrophobic surface across days. Group D2 exhibited the least cytotoxicity at all time intervals. Group E4 displayed the highest antifungal activity. ConclusionWithin study limitations, silicone soft liners modified with 0.25 % and 0.5 % cerium oxide nanoparticles exhibited superior properties in surface hardness and cytotoxicity. Optimal surface morphology and wettability were observed with 0.5 % concentration, while antifungal efficacy peaked at 1 %. These findings suggest clinical potential for treating damaged oral tissues. Clinical implicationsSoft liners modified with 0.25 % and 0.5 % cerium oxide nanoparticles may benefit patients with oral tissue abuse, offering enhanced therapeutic properties.

Multi-functional ceramic glazes with nano ZnO/Cu–ZnO incorporation

The study successfully enabled the creation of ceramic surfaces with multi functionalities, including superhydrophilicity, self-cleaning, antibacterial properties, and photocatalytic activity, by applying a glaze composition rich in nano ZnO/Cu–ZnO and utilizing surface chemistry and unique texturing on porcelain tiles. The tiles, coated with unique glaze compositions, were fired in an industrial furnace and heat treated. The crystalline phases and surface morphology of glazed surfaces were systematically evaluated using XRD, SEM, FT-IR, drop shape analyzer, and surface roughness profilometer. Key-factors affecting the wettability, self-clean ability, photocatalytic activity and antibacterial efficacy were discussed. Adding nano Cu into the glaze mixture that is rich in ZnO improves the evolution of zincite crystals, increases the specific surface energy, decreases surface roughness, provide superhydrophilicity and promotes the antibacterial effectiveness and photocatalytic activity. Superhydrophilic surfaces doped with nano Cu–ZnO display antibacterial characteristics that do not require UV or visible light. The quick achievement of complete self-cleaning, up to 100 %, is due to the presence of nano Cu particles in its structure. Hydrophilicity has the ability to improve the efficiency of photocatalysis. If a surface exhibits superhydrophilic properties, it shows exceptional photocatalytic performance. A surface that is solely photohydrophilic may not maintain self-cleaning. Hydrophilicity may be more important than photocatalysis in the self-cleaning effect.

Liquid drop shapes on hexagonal substrates: corner dewetting in the context of vapor–liquid–solid growth of nanowires

Liquid drop shapes on hexagonal substrates: corner dewetting in the context of vapor–liquid–solid growth of nanowires

Shaping in the Third Direction: Colloidal Photonic Crystals with Quadratic Surfaces Self-Assembled by Hanging-Drop Method.

High-quality, 3D-shaped, SiO2 colloidal photonic crystals (ellipsoids, hyperboloids, and others) were fabricated by self-assembly. They possess a quadratic surface and are wide-angle-independent, direction-dependent, diffractive reflection crystals. Their size varies between 1 and 5 mm and can be achieved as mechanical-resistant, free-standing, thick (hundreds of ordered layers) objects. High-quality, 3D-shaped, polystyrene inverse-opal photonic superstructures (highly similar to diatom frustules) were synthesized by using an inside infiltration method as wide-angle-independent, reflective diffraction objects. They possess multiple reflection bands given by their special architecture (a torus on the top of an ellipsoid) and by their different sized holes (384 nm and 264 nm). Our hanging-drop self-assembly approach uses setups which deform the shape of an ordinary spherical drop; thus, the colloidal self-assembly takes place on a non-axisymmetric liquid/air interface. The deformed drop surface is a kind of topological interface which changes its shape in time, remaining as a quality template for the self-assembly process. Three-dimensional-shaped colloidal photonic crystals might be used as devices for future spectrophotometers, aspheric or freeform diffracting mirrors, or metasurfaces for experiments regarding space-time curvature analogy.

Role of drop shape on drop impact with solidification

Role of drop shape on drop impact with solidification

From weakly to strongly nonlinear viscous drop shape oscillations: An analytical and numerical study

Nonlinear axisymmetric shape oscillations of a Newtonian drop in a vacuum are investigated using two different theoretical methods, for fundamental interest and for the significance of the oscillations in transport processes across the drop surface. The extended discontinuous Galerkin method is contrasted to the weakly nonlinear theory. While the former allows large drop surface deformation amplitudes to be analyzed with high precision and drop volume errors below 0.11% even at the largest deformations, the latter provides analytical insight into the origin of quasiperiodic time behavior of the oscillations and reveals the oscillation modes coupled in the nonlinear motion. Results from both methods for moderate initial deformation amplitudes at modes of initial drop deformation m=2, 3, and 4 are in excellent agreement, showing the time asymmetry of the oscillation and the decrease of the oscillation frequency with increasing deformation amplitude. The Fourier power spectra for the first oscillation period exhibit decreased dominant frequencies as compared to the linear results as well as the mode coupling as nonlinear effects. The numerical method is used to compute the oscillatory and damping behavior of viscous drops, as well as the interconversion of kinetic and surface energies during the oscillations at strong initial deformations. Published by the American Physical Society 2024

Effects of salinity, temperature, and pressure on H2–brine interfacial tension: Implications for underground hydrogen storage

Underground hydrogen (H2) storage is a long-term, clean, and sustainable solution for a large-scale H2 economy. Hydrogen geo-storage strategies in saline aquifers have gained considerable attention regarding meeting energy demand challenges. Rock-fluid interaction and interfacial tension (IFT) of any given gas determine the fluid flow, storage potential, and containment security. However, the literature lacks sufficient information on the IFT of H2-brine systems at various thermophysical and salinity conditions. This study experimentally measures density using an Anton Paar DMA-HP densitometer and IFT with a Kruss drop shape analyzer (DSA-100). The density and IFT measurements of H2-brine systems were evaluated at various pressures (0.1, 5, 10, 15, and 20 MPa), temperatures (25, 50, and 70 °C), and salinities, including deionized water, seawater (mixed brine), and individual brines (NaCl, KCl, MgCl2, CaCl2, and Na2SO4) at 1 and 3 M concentrations. The results indicate a significant decrease in H2-brine IFT by the increasing temperature at a constant pressure and salinity. A slightly decreasing trend is observed when the H2-brine IFT is plotted against pressure, maintaining a constant salinity and temperature. Increasing the salinity of the salt solutions (from 1 to 3 M), irrespective of the salt type, increases the H2-brine IFT at a constant pressure and temperature. Due to the screening effect, the monovalent and divalent cations behave differently in H2. To the best of our knowledge, this comprehensive dataset for H2-brine IFT is presented for the first time. The provided data are crucial for reservoir simulations and determining the H2 geo-storage potential under natural reservoir conditions.

Comparative study of surface preparation for paint adhesion on CF-PEKK composites: Plasma, Chemical, and Flame treatment

Polyether ketone-ketone (PEKK) is a high-performance thermoplastic, and its fiber composites have various engineering applications. Fiber reinforced composites in long-term applications require a protective layer of coatings to avoid environmental degradation. In this work, the surface energy of carbon fiber-PEKK composites was modified by flame, chemical, and plasma treatments to improve paint adhesion. A detailed study was carried out to understand the physical, morphological, and chemical surface characteristics due to different surface treatments. We found through XPS that highly active surface functionalities (− C-Ȯ/−C = Ȯ) due to oxidation at the ketone/ether groups were for surface adhesion. In support of the enhanced surface functionality, we have also evaluated the wetting behavior of paint with respect to different treated surfaces using drop shape analyzer and found that the polar component of the surface free energy increased for all treatments compared to pristine. Surface crystallinity after surface treatment was assessed using XRD; flame and plasma showed reduced surface crystallinities (25.92 % and 38.18 %, respectively), compared to pristine (46.78 %), and yielded a good adherend for coatings. Surfaces with good wettability and functionalities show good adhesion between the paint and PEKK composites as found through adhesion tests following ASTM D3359. The findings demonstrate that plasma surface treatment outperformed flame and chemical treatments in terms of adhesion of the paint to the surface.

Colorimetric sensor for copper and lead using silver nanoparticles functionalized with fluoresceinamine isomer I

Chemical sensing of heavy metals in aqueous environments offers significant advantages, including a rapid and cost-effective method for estimating their concentrations. In this study, silver nanoparticles (AgNPs) were functionalized with fluoresceinamine (FLA) to detect Cu2+and Pb2+in water. Cysteamine (Cyt) was subsequently added to detect these metals with the naked eye. UV–Vis and fluorescence spectroscopy were conducted to determine the limits of detection (LODs) of each method. All AgNPs were characterized using transmission electron microscopy and Fourier transform infrared spectroscopy. The lower LODs using Cu2+and Pb2+ were 4.40 × 10−6 and 1.15 × 10−6 M for UV–Vis titration and 6.53 × 10−6 and 1.39 × 10−6 M for fluorescence, respectively. The recovery percentage for the spectroscopic methods was high at 87 %. Subsequently, cellulose paper sensors were impregnated with AgNPs-FLA and AgNPs-FLA-Cyt to analyze both cations with a limit of quantification (LOQ) of 10−3 M. The cellulose paper sensors were characterized using drop shape analysis and fluorescence. These findings demonstrate the potential of colorimetric sensors composed of AgNPs-fluorophores for the rapid estimation of the concentration of specific heavy metals in solution using UV–Vis and fluorescence spectroscopy. Further, the incorporation of an additional molecule, such as Cyt, linked to AgNPs-fluorophores enabled detection with the naked eye, offering potential utility in water analysis for mining industries characterized by high concentrations of contaminants.

Data-driven modeling of the aerodynamic deformation and drag for a freely moving drop in the sub-critical Weber number regime

Accurate prediction of the dynamics and deformation of freely moving drops is crucial for numerous droplet applications. When the Weber number is finite but below a critical value, the drop deviates from its spherical shape and deforms as it is accelerated by the gas stream. Since aerodynamic drag on the drop depends on its shape oscillation, accurately modeling the drop shape evolution is essential for predicting the drop’s velocity and position. In this study, 2D axisymmetric interface-resolved simulations were performed to provide a comprehensive dataset for developing a data-driven model. Parametric simulations were conducted by systematically varying the drop diameter and free-stream velocity, achieving wide ranges of Weber and Reynolds numbers. The instantaneous drop shapes obtained in simulations are characterized by spherical harmonics. Temporal data of the drag and modal coefficients are collected from the simulation data to train a Nonlinear Auto-Regressive models with eXogenous inputs (NARX) neural network model. The overall model consists of two multi-layer perceptron networks, which predict the modal coefficients and the drop drag, respectively. The drop shape can be reconstructed with the predicted modal coefficients. The model predictions are validated against the simulation data in the testing set, showing excellent agreement for the evolutions of both the drop shape and drag.

Study of Nanohydroxyapatite Coatings Prepared by the Electrophoretic Deposition Method at Various Voltage and Time Parameters.

The aim of the work is to compare the properties of nanohydroxyapatite coatings obtained using the electrophoretic deposition method (EDP) at 10 V, 20 V, and 30 V, and with deposit times of 2 and 5 min. The primary sedimentation was used to minimize the risk of the formation of particle agglomerates on the sample surface. Evaluation of the coating was performed by using a Scanning Electron Microscope (SEM), Energy-Dispersive Spectroscopy (EDS), Atomic Force Microscopy (AFM), optical profilometer, drop shape analyzer, and a nanoscratch tester. All of the coatings are homogeneous without any agglomerates. When low voltage (10 V) was used, the coatings were uniform and continuous regardless of the deposition time. The increase in voltage resulted in the formation of cracks in the coatings. The wettability test shows the hydrophilic behavior of the coatings and the mean contact angle values are in the range of 20-37°. The coatings showed excellent adhesion to the substrate. The application of a maximum force of 400 mN did not cause delamination in most coatings. It is concluded that the optimal coating for orthopedic implants (such as hip joint implants, knee joint implants or facial elements) is obtained at 10 V and 5 min because of its homogeneity, and a contact angle that promotes osseointegration and great adhesion to the substrate.

Effect of Heating Surface Geometry on the Droplets Evaporation under Leidenfrost Conditions

Physical and geometric factors are generally regarded as the main cause of evaporation characteristics of the Leidenfrost droplets levitating above the hot surface. It is well-known and generally accepted that similar research is conducted under different conditions and on individual measurement set-ups. This is one of the potential reasons for the differences in the results of thermal fluxes and computational models in scientific papers. This paper discusses the influence of the heating surface geometry on the heat transfer coefficient h during water drops evaporation under film boiling regime. The variable geometry parameters are the curvature radius of the heating bowl of R = 64 and 254 mm. Individually compiled test stands made it possible to measure the instantaneous drop mass for each R radius and to determine the coefficient h. The methodology was validated by calculating the relative error. It changes with the curvature radius and the droplet size, and for droplet mass from about 2 g to 0.3 g does not exceed ±10%. The heat transfer coefficient h is about 15% higher for a drop located on a surface with a larger radius of curvature. Moreover, the method that was devised allows us to estimate the h value for asymmetric droplet shapes. The advantage of the adopted method of measuring the drop mass over time is the possibility of analyzing heat transfer processes in any drop shape range, even in the case of asymmetric ones. Previous research methods were mainly based on determining the mass of the drop by calculating its volume.

Dynamics and active mixing of a droplet in a Stokes trap

Particle trapping and manipulation have a wide range of applications in biotechnology and engineering. Recently, a flow-based, particle-trapping device called the Stokes trap was developed for trapping and control of small particles in the intersection of multiple branches in a microfluidic channel. This device can also be used to perform rheological experiments to determine the viscoelastic response of an emulsion or suspension. We show that besides these applications, the various flow modes produced by the Stokes trap are able to manipulate drop shapes and induce active mixing inside droplets. To this end, we analyse the dynamics of a droplet in a Stokes trap through boundary-integral simulations. We also explore the dynamic response of drop shape with respect to distinct external flow modes, which allows us to perform numerical experiments such as step strain and oscillatory extension. A linear controller is used to manipulate drop position, and the drop deformation is characterized by a spherical-harmonic decomposition. For small drop deformations, we observe a linear superposition of harmonics, which, surprisingly, seems to hold even for moderate deformations. This result indicates that such a device can be used for shape control of droplets. We also investigate how the different flow modes may be combined to induce mixing inside the droplets. The transient combination of modes produces an effective chaotic mixing, which is characterized by a mixing number. The mixing inside the droplet can be further enhanced for lower viscosity ratios and low, but non-zero capillary number and flow frequencies.

Surface Roughness, Dynamic Wettability, and Interphase of Modified Melamine Formaldehyde-Based Adhesives on Jabon Wood.

The surface roughness and wettability of wood are critical aspects to consider when producing laminated wood products with adhesive applications. This study aims to investigate the surface roughness and dynamic wettability of Jabon wood in the presence of melamine formaldehyde (MF)-based adhesives. Commercial MF adhesives (MF-0) and modified MF adhesives (MF-1) were applied to Jabon wood, which includes tangential (T), radial (R), and semi-radial (T/R) surfaces. The surface roughness of Jabon wood was assessed using a portable stylus-type profilometer. The low-bond axisymmetric drop shape analysis (LB-ADSA) method was employed to identify the contact angle (θ) of the MF-based adhesives on Jabon wood. The wettability was determined by evaluating the constant contact angle change rate (K value) using the Shi and Gardner (S/G) model. Dynamic mechanical analysis (DMA) was employed to investigate the viscoelastic characteristics of the interphase analysis of the wood and MF-based adhesives. The roughness level (Ra) of the Jabon board ranged from 5.62 to 6.94 µm, with the T/R having a higher level of roughness than the R and T. MF-0 exhibited a higher K value (0.262-0.331) than MF-1 (0.136-0.212), indicating that MF-0 wets the surface of Jabon wood more easily than MF-1. The wood-MF-0 interphase reached a maximum stiffness of 957 N/m at 123.0 °C, while the wood-MF-1 had a maximum stiffness of 2734 N/m at 110.5 °C. In addition, the wood-MF-0 had a maximum storage modulus of 12,650 MPa at a temperature of 128.9 °C, while the wood-MF-1 had a maximum storage modulus of 22,950 MPa at 113.5 °C.