Test Liquids Research Articles

Efficacy for aspiration prevention through thickening of liquid foods evaluated using a swallowing model apparatus

Abstract An apparatus simulating the swallowing process of liquid foods was constructed using a flow channel. In the channel, a circular cylindrical obstruction was fixed to serve as an epiglottis in the mesopharynx. The apparatus was designed with an adjustable gate for flow control to represent the processes of healthy swallowing and dysphagia. The parameters considered were the holding time and flow resistance controlled by the gate, which were assumed to indicate the swallowing reflex and power, respectively. When a Newtonian liquid with relatively low viscosity was used, the flow experiment performed using the apparatus under conditions of shorter holding time and larger flow resistance successfully reproduced a phenomenon similar to aspiration in a patient with dysphagia. In addition to a Newtonian liquid with high viscosity, non-Newtonian liquids thickened to various concentrations using commercially available thickeners were used. In flow experiments with these test liquids, the efficacy for aspiration prevention was inferred based not only on the viscosity of the liquid but also its elasticity, depending on its viscosity.

Characterization of the Alkali and Hydrolysis Resistance of Polymer-Impregnated, Alkali-Resistant Glass Filaments.

The aim of this series of tests was to characterize the alkali and water resistance of alkali-resistant (durability) glass filaments, which were optimized with two non-vulcanized formulations based on co-polymerizing styrene-butadiene rubbers (CemFil-SBR1 and CemFil-SBR2). Furthermore, it was assessed which of the two polymer-impregnated multifilament yarns is the better alternative for use in cementitious binders. For this purpose, the impregnated multifilament yarns were chemically conditioned for up to twelve months at temperatures of 23 and 50 °C in 2.5 percent sodium hydroxide solution and 2.5 percent potassium hydroxide solution as well as in 3 percent salt and distilled water. The samples were then subjected to material science tests. The liquid absorption capacities and the changes in the mass of the composite materials were determined at different times during conditioning. The load-bearing capacity of the samples was also tested using uniaxial fiber strand tensile tests. The durability of the polymer-impregnated multifilament yarns was described in detail in conjunction with scanning electron microscopy images and nominal cross-section determinations. The test liquids caused a reduction in strength during the storage period, which was accelerated by increased temperatures. The reduction in strength is mainly due to glass corrosion of the filaments. Glass corrosion is delayed due to the good impregnation quality, which fundamentally improves the durability of the yarns. The results of the durability tests show that the polymer-impregnated multifilament yarns CemFil-SBR2 are probably more suitable for use in cementitious binders, as they have better alkali and hydrolysis resistance.

Physicochemical Characteristics of Porous Starch Obtained by Combined Physical and Enzymatic Methods-Part 2: Potential Application as a Carrier of Gallic Acid.

Wettability measurements were performed for aqueous dispersions of native and modified corn, potato, and pea starch granules deposited on glass plates by the thin layer method using test liquids of a different chemical nature (polar water and formamide or non-polar diiodomethane). High values of the determination coefficient R2 confirm that the linear regression model describes the relationship between the wetting time and the square of the penetration distance very well, indicating the linear nature of the Washburn relationship. A change in free energy (enthalpy) during the movement of the liquid in the porous layer was determined for all starches before and after modification in contact with test liquids. Wetting times for polar liquids increased significantly (from 3 to 4 fold), especially for corn starch. The lower the value of the adhesive tension, the easier the wetting process takes place, and consequently, the adsorption process is facilitated. Adhesive tension for polar substances applies to the adsorption of hydrophilic substances, while in the case of apolar substances, adhesive tension applies to the adsorption of hydrophobic substances. For the adsorption of gallic acid on starch, the relationships obtained for polar substances are crucial. The adsorption of gallic acid by forming hydrogen bonds or, more generally, donor-acceptor (acid-base) bonds is definitely higher for corn starch than other starches. Therefore, this starch has the most significant potential for use as a carrier of gallic acid or, more broadly, compounds from the polyphenol group.

Wetting transitions in adhesive surfaces of polystyrene: The petal effect

HypothesisThe petal effect is a well-known natural phenomenon in surface science and has served as inspiration for the creation of several materials with superhydrophobic qualities and high adhesion. As surface roughness has a crucial role in these properties, being able to modulate it could help us design materials at will. Capillary penetration frustrates diffusion and promotes large contact angles as well as high adhesion. ExperimentsPolystyrene surfaces were created using the spin-coating technique. By varying the polymer concentration, the surface roughness was modified. To determine the roughness parameters, atomic force microscopy was used. We recorded advancing and receding contact angles using water and glycerol as test liquids to study contact angle hysteresis, the work of adhesion and the apparent surface energy, which was determined with the Chibowski and Perea–Carpio method. For the purpose of elucidating the wetting states, captive bubble experiments were conducted. FindingsUsing an easy method, we create polystyrene surfaces with both superhydrophobicity and strong adhesion, where the roughness area factor regulates wetting transitions from Cassie–Baxter to Wenzel. The receding contact angle suggests capillary penetration, which we demonstrate by captive bubble experiments. In addition, a link was found between the surface roughness and apparent surface energy.

Characterization of the Chemical Resistance of Two Non-Vulcanized Styrene-Butadiene Rubbers (SBR).

The objective of this series of tests is to characterize the alkali and water resistance of two non-vulcanized formulations based on co-polymerizing styrene-butadiene rubbers (SBR1 and SBR2). The relative merits of the two polymer systems as impregnating agents for alkali-resistant glass reinforcement in cementitious binders are assessed. For this purpose, polymer films were synthesized and then chemically conditioned for up to half a year at temperatures of 23 °C and 50 °C in sodium hydroxide and potassium hydroxide solutions as well as in salt and distilled water. Changes in mass, tensile strength, and material hardness were evaluated to assess the chemical resistance of the two polymer systems. The different test liquids generally led to swelling (increase in mass) and degradation (reduction in mass) of the polymer structures. These two processes occurred simultaneously. The liquid absorption capacity of the SBR1 impregnation system was between 25.05% and 51.60% by weight, depending on the test liquids. In contrast, the SBR2 impregnation system exhibited a lower liquid absorption capacity, with a weight increase from 21.19% to 42.90%. The chemical conditioning resulted in a maximum mass reduction of the polymer structure SBR1 of 8.82% by weight. The polymer SBR2, on the other hand, only lost up to 2.88% by weight. The tensile strengths of the unconditioned samples of the polymer systems SBR1 and SBR2 were 55.49 ± 7.47 N and 80.87 ± 15.96 N, respectively. The test liquids caused a reduction in strength over the storage period which was accelerated by increased temperatures. The loss of strength of the polymer structure SBR2 was lower over the entire conditioning period. In this context, a correlation was found between strength and material hardness. Overall, the polymeric impregnation system SBR2 had a lower liquid absorption capacity and a lower degree of damage caused by the degrading test liquids. Furthermore, the tensile strength was generally higher and more robust over the entire conditioning period. The results of the durability tests indicate that the SBR2 polymer system is more suitable for use in cementitious binders, as it exhibits less degradation of the polymer structure in response to chemical aging processes.

Получение и обработка акустических откликов волн Лэмба в датчиках водных растворов базовых вкусов

In this work, the total acoustic wave losses in 128°Y-LiNbO3 wafers during liquid application due to radiation emission of waves into the liquid medium, as well as its viscosity, conductivity, density and dielectric constant of the liquid analyte are measured. Solutions with 5 basic flavors, widely used for calibration and reference creation in liquid media testing, were selected as test liquids. The measurements were performed in the range of 30...60 MHz. After the measurements, the experimental data were presented in the form of polar histograms, from the comparison of areas and shapes of which the flavor of a particular liquid was determined. Then, a principal component analysis (PCA) method was applied to the same experimental results to describe linear elastic wave deformation processes based on experimental data containing known values of physical wave measurements for different types of liquid media, which was previously used to identify gases and predict the properties of various substances from the linear response of a normal acoustic-electronic wave. In this paper, a comparative analysis of the results obtained using polar histograms and the standard PCA classification method is performed. The advantages of the latter are demonstrated. The results of this study are useful both for the development of acoustic sensors without sensor layers and for the application of machine learning methods to data in other types of sensors.

Wetting Transparency of Single-Layer Graphene on Liquid Substrates.

Graphene's wetting transparency offers promising avenues for creating multifunctional devices by allowing real-time wettability control on liquid substrates via the flow of different liquids beneath graphene. Despite its potential, direct measurement of floating graphene's wettability remains a challenge, hindering the exploration of these applications. The current study develops an experimental methodology to assess the wetting transparency of single-layer graphene (SLG) on liquid substrates. By employing contact angle measurements and Neumann's Triangle model, the challenge of evaluating the wettability of floating free-suspended single-layer graphene is addressed. The research reveals that for successful contact angle measurements, the testing and substrate liquids must be immiscible. Using diiodomethane as the testing liquid and ammonium persulfate solution as liquid substrate, the study demonstrates the near-complete wetting transparency of graphene. Furthermore, it successfully showcases the feasibility of real-time wettability control using graphene on liquid substrates. This work not only advances the understanding of graphene's interaction with liquid interfaces but also suggests a new avenue for the development of multifunctional materials and devices by exploiting the unique wetting transparency of graphene.

The breakup and instability structures of liquid jets in subsonic crossflows

The breakup of water and Jet A fuel jets injected transverse into elevated temperature (up to 425 °C), combustion pre-heated, subsonic crossflows was investigated by internally fluorescing the liquid jet column. The fluorescent dye seeded test liquids were illuminated by a pulsed laser light that was transmitted within the injector using a quartz rod light-guide. High-resolution images isolating the intact liquid column from light scattered by the surrounding dense spray facilitated precise measurement of the liquid column breakup position and the size and distribution of windward column instability waves. The injector geometry consisted of a 1 mm circular orifice with an orifice length of 20 mm with a tapered inlet. Liquid jet to gaseous crossflow momentum flux ratios were varied from 6 to 266 and the gas Weber number was varied from 10.7 to 228. Empirical correlations were derived for the liquid column breakup coordinates and breakup time in addition to the average and local maximum instability wavelength and amplitude on the liquid column windward surface. The reported correlations provided key insight into atomization physics and aim to support the quantitative validation of high-fidelity numerical simulations of the liquid jet in subsonic crossflow.

Engineering PVDF omniphobic membranes with flower-like micro-nano structures for robust membrane distillation

Conventional PVDF membranes are easily wetted and contaminated in membrane distillation (MD) process, especially when used in separating high-salinity water and oil-contained saline water. To address these issues, an omniphobic membrane was fabricated in this work. ZnO micro-flowers with a rough structure were successfully deposited onto the PVDF membrane with the assistance of polydopamine assistance. After undergoing a fluorination process, the omniphobic membranes were prepared by the synergistic effect of surface microstructure and free energy. The effects of varying Zn(NO3)2 concentrations and deposition times on morphology, pore size and separation efficiency were comprehensively examined. It was demonstrated that at a Zn(NO3)2 concentration of 50 mM and a deposition time of 0.5 h, the resulting PVDF composite membrane exhibited high liquid repellency towards all the test liquids, such as water, ethanol solution, paraffin oil, and etc. Furthermore, the membrane consistently exhibited impressive salt rejection behavior (99.99%) and maintained an average flux (15.54 kg·m−2·h−1) when exposed to high-salinity solution (up to 20 wt%-NaCl). Meanwhile, during treating an oil-contained saline water emulsion with the oil content of 200 ppm, the membrane also displayed high resistance to wetting and fouling during the continuously 24 h tests. The membrane displayed a rejection rate of 99.99 % with an average vapor flux of 18.60 kg·m−2·h−1. In summary, this omniphobic membranes demonstrated a great potential in MD for practical challenging wastewater treatment.

Examining the interfacial behavior of non-Newtonian gas-liquid two-phase flow in horizontal square microchannels

This study investigates the flow dynamics of a non-Newtonian two-phase flow within a horizontal square microchannel. The experimental apparatus employed an acrylic channel with a side length of 8 × 10−4 m. Nitrogen served as the test gas, and the test liquids consisted of water and CMC (Carboxymethylcellulose) aqueous solutions at concentrations of 0.2 and 0.4 %wt. The superficial velocity of working gas and liquids spanned ranges of 0.26–20 m/s and 0.05–1.0 m/s, respectively. A differential pressure transducer was used to measure pressure gradients, while a high-speed video camera captured the flow behavior for analysis with a custom image processing technique. Nonlinear regression statistical analysis was applied to establish the criteria for flow pattern transition. Furthermore, signal processing techniques such as PSD (Power Spectral Density), DWT (Discrete Wavelet Transform), ANN (Artificial Neural Network), and Kolmogorov entropy were employed to analyze the flow behavior based on the pressure gradient signals from the differential pressure transducers. Our findings reveal the occurrence of bubbly, slug, slug-annular, and churn flow patterns. The nonlinear regression statistical analysis offered ambiguous results for determining flow pattern transitions. However, an empirical coefficient was obtained for the nondimensional liquid height. Moreover, the empirical nondimensional liquid height aligned well with the experimental values. The PSD and DWT analysis corroborated each other in clearly characterizing the flow pattern based on pressure gradient fluctuation and wavelet energy. The Kolmogorov entropy effectively captured the chaotic flow pattern. Furthermore, the ANN analysis demonstrated a solid agreement between the predicted and actual flow patterns.

Wilhelmy balance—A simple and reliable method for determining immersion angles and surface energies even on non‐planar and complex geometries?

The growing significance of surface properties in modern materials, particularly in medical technology, drives the need for accurate characterization techniques. Traditional contact angle measurements face challenges when applied to intricate surfaces like dental implants. Here, tensiometry applying the Wilhelmy plate method has been described in the last decade to offer one solution for the evaluation of complex surface geometries by quantifying apparent contact angles based on wetting forces. This study evaluates a simple setup employing the Wilhelmy balance concept for immersion angle determination. Instead of using a force sensor as in tensiometers, the wetting force is determined via changes in mass signal by means of an analytical balance available in standard laboratories. The force is thus recorded inverse to conventional tensiometry. The approach was validated on diverse geometries and extended to intricate structures, including plasma‐treated dental implants. Results were compared to conventional contact angle analysis systems underlining the reliability of the method in characterizing non‐planar and complex surfaces. Additionally, the method was successfully extended to the evaluation of surface energies on planar and non‐planar surfaces using various solvent sets. However, results evidenced that specimen geometry can influence the measurements to such an extent that immersion contact angles can no longer be calculated due to capillary effects. An outlook suggests further exploration with a wider range of test liquids to enhance accuracy in surface energy determination.

Determination of Electrical and Mechanical Properties of Liquids Using a Resonator with a Longitudinal Electric Field

The possibility of determining the elastic modules, viscosity coefficients, dielectric constant and electrical conductivity of a viscous conducting liquid using a piezoelectric resonator with a longitudinal electric field is shown. For the research, we chose a piezoelectric resonator made on an AT-cut quartz plate with round electrodes, operating with a shear acoustic mode at a frequency of about 4.4 MHz. The resonator was fixed to the bottom of a 30 mL liquid container. The samples of a mixture of glycerol and water with different viscosity and conductivity were used as test liquids. First, the frequency dependences of the real and imaginary parts of the electrical impedance of a free resonator were measured and, using the Mason electromechanical circuit, the elastic module, viscosity coefficient, piezoelectric constant and dielectric constant of the resonator material (quartz) were determined. Then, the container was filled with the test sample of a liquid mixture so that the resonator was completely covered with liquid, and the measurement of the frequency dependences of the real and imaginary parts of the electrical impedance of the loaded resonator was repeated. The dependences of the frequency of parallel and series resonances, as well as the maximum values of the electrical impedance and admittance on the conductivity of liquids for various viscosity values, were plotted. It was shown that these dependences can be used to unambiguously determine the viscosity and conductivity of the test liquid. Next, by fitting the theoretical frequency dependences of the real and imaginary parts of the electrical impedance of the resonator loaded with the liquid under study to the experimental dependences, the elastic module of the liquid and its dielectric constant were determined.

A dual-height wick to improve capillary performance of vapor chambers

The wick performance is a crucial metric for ensuring the reliable and efficient operation of vapor chambers (VCs) away from dry-out. To enhance the performance of VC, a pitcher plant inspired enhanced wick characteristic dual-height microgrooves (DHMW) was fabricated on 6063 aluminum alloy by one-step picosecond laser texturing without chemical modification. This study describes the two-step capillary behavior of DHMW by high-speed camera and infrared camera. The effects of minor rib number, groove height ratio, length scale, and test liquids (water, acetone, ethanol) on the capillary performance were investigated. When using water as the working fluid, the DHMW achieved a K/Reff of 1.182 µm, which was about 71.3 % larger than that of normal microgroove wicks due to the liquid propagation effect and the flow resistance reduction effect. Furthermore, the maximum K/Reff could reach 1.819 µm of the sample with a minor rib depth of about 70 μm. However, the wetting results showed that the droplets of acetone and ethanol tend to spread laterally after contact with the surface, which is unfavorable for the formation of hierarchical transport in the DHMW. This study demonstrates that laser texturing is an effective and controllable method for the complex shaping of grooved aluminum wicks, with the potential to improve the heat transport capability of VCs.

Study of the surface energy characteristics of glass and carbon fiber by the Washburn method

The Washburne adsorption method (capillary rise method), as an alternative to the standard single fiber method, is proposed to investigate the surface energy characteristics of glass and carbon fibers using a K- 100 processor tensiometer. The paper considers sample preparation of fibrous materials measured by the Washburn method: filling a Teflon tube with glass and carbon fibers, packing density of the resulting capillary, and determination of the capillarity constant. The results of measurements of the wettability of fibers in test liquids (water, hexane) and in the solution epoxy binder UP-2227N are presented. The influence of appretting on the surface energy characteristics of glass fiber and carbon fiber was studied, a comparative analysis of the obtained values (wetting angle, SEP, adhesion) was carried out before and after the removal of lubricants.

The Effect of Different Soft Drinks on the Force Degradation of Conventional and Memory Orthodontic Elastic Chains: An In-Vitro Study.

Objectives: The aim of this study was to assess how different soft drinks affect the deterioration of conventional and memory orthodontic elastomeric chains. Materials and Methods: We used 500 five-loop segments of elastomeric chains, which were divided into two equal groups of conventional and memory chains. The samples were kept in artificial saliva during the study period. Each group was further divided into 5 subgroups consisting of artificial saliva (controls), Coca-Cola®, non-alcoholic beer (ISTAK®), and carbonated and non-carbonated yoghurt-based drinks (Alis®). Treatment with the soft drinks consisted of immersion in the test liquids twice a day for 3 minutes each time. Force measurements were taken on days 1, 7, 14, 21, and 28. Data were analyzed using One- and three-way ANOVA tests, and independent t-test, with a significance level of 5%. Results: The mean initial force for the conventional and memory elastomeric chains was 3.34±0.112N and 2.49±0.209N, respectively. Conventional chains showed significantly greater degradation than memory chains (P<0.01). Soft drinks had a significant impact on force degradation for both types of chains at all time points (P<0.01). Coca-Cola® had the highest level of force degradation, while non-carbonated yoghurt-based drinks had the lowest (P<0.01). Conclusion: Based on the findings of this study, it is recommended that orthodontic patients choose non-carbonated yoghurt-based drinks during their treatment. Memory elastomeric chains may be more suitable for patients who consume large amounts of carbonated soft drinks, due to their lower amount of force degradation compared to conventional chains.

Intensity Ratio Distribution in Different Dielectric Liquids using Kerr Effect Method

Light intensity is the result from the Kerr effect measurement that can be used in determining the electric field distributions in dielectric liquids as the analysis continues afterwards. One of the most important parameters to consider in designing the Kerr effect experiment is the Kerr constant of the test liquid. This paper aims to study and compare light intensity distribution in different dielectric liquids using Kerr effect method. Propylene carbonate, transformer oil and purified water are used as the test liquids. From the results obtained, the light intensities as a function of electric field of the test liquids are compared. With higher Kerr constant, low voltages can be applied to the test liquid but with larger optical signals. Furthermore, the length of the electrodes can be designed accordingly to suit the experimental setup.

Bio Water Based Liquid Penetrants and Magnetics: a safer and cost-efficient solution for today

The objective of this paper is to present a study on the contribution of the superficial methods (Liquid Penetrants and Magnetic Testing (MT) liquids) in the NDT industry to the European Union and International targets of achieving climate neutrality. Bio water based liquid penetrants and MT liquids are available since some years in the NDT industry and are already widely used by medium and large companies worldwide, but their use has been limited in the past due to: higher costs, lower sustainability awareness, practical application process. (Please see previous contributions here: https://www.ndt.it/uk/documents.asp for technical papers presented on water-based liquid penetrants and MT liquids). Recently, the combination of higher oil and solvents prices internationally and an increased environmental consciousness by most Companies worldwide have turned the situation, so nowadays more and more Companies use safer Bio water-based products in their everyday work to achieve better operator and environment safety and lower overall costs. This paper will present effectively the advantages for the operator, the environment, and the Companies’ global costs of using Bio water based liquid penetrants and MT liquids in their NDT quality control process, through: a) A review of the updated applicable International Standards; b) An analysis of the safety and costs advantages of using Bio water based liquid penetrants and MT liquids compared to VOCs-containing alternatives; c) Real Companies case studies in the NDT industry; d) Examples of indications using Bio water based penetrants and MT liquids on metal pieces and on artificial defects as described in the International Standards.

Method to Measure Surface Tension of Microdroplets Using Standard AFM Cantilever Tips.

Surface tension is a physical property that is central to our understanding of wetting phenomena. One could easily measure liquid surface tension using commercially available tensiometers (e.g., Wilhelmy plate method) or by optical imaging (e.g., pendant drop method). However, such instruments are designed for bulk liquid volumes on the order of milliliters. In order to perform similar measurements on extremely small sample volumes in the range of femtoliters, atomic force microscope (AFM) is considered as a promising tool. It was previously reported that by fabricating a special "nanoneedle"-shaped cantilever probe, a Wilhelmy-like experiment can be performed with AFM. By measuring the capillary force between such special probes and a liquid surface, surface tension could be calculated. Here, we carried out measurements on microscopic droplets with AFM, but instead, using standard pyramidal cantilever tips. The cantilevers were coated with a hydrophilic polyethylene glycol-based polymer brush in a simple one-step process, which reduced its contact angle hysteresis for most liquids. Numerical simulations of a liquid drop interacting with a pyramidal or conical geometry were used to calculate surface tension from the experimentally measured force. The results on micrometer-sized drops agree well with bulk tensiometer measurement of three test liquids (mineral oil, ionic liquid, and glycerol), within a maximum error of 10%. Our method eliminates the need for specially fabricated "nanoneedle" tips, thus reducing the complexity and cost of measurement.

A Comparison of the Wetting Ability of Three Artificial Saliva Substitutes on Heat-Cured Denture Base Resin - An In vitro Study.

Salivary substitutes are gaining popularity these days because of the increase in patients with dry mouth. These substitutes must satisfy certain criteria to fulfill the patient's needs. One of these is wettability. One hundred fifty rectangular specimens of heat-cured denture base acrylic resin were prepared. A drop of test liquids (human saliva, distilled water, aqwet, saleva, and wet mouth) was placed over the test specimen and right and left contact angles were measured using optical contact angle machine. All test liquids performed better than distilled water. Human saliva has the least contact angle followed by aqwet. Carboxymethyl cellulose base aqwet saliva substitute was found to be best having similar contact angle values to human saliva.

Wetting model of rough solid surfaces and the effect of aggregate properties on epoxy resin binder-aggregate interface wetting

In order to study the effect of aggregate characteristics on the wetting of epoxy resin binder-aggregate interface, based on the Wenzel model and Cassie model, this paper established a new wetting model of the irregular rough surface. The model regularizes the rough solid surface and can calculate the wetting depth and apparent contact angle between different irregular rough solids and liquids. The texture parameters of aggregates, the surface tension of test liquids and the contact angles of different liquids-aggregates were tested by laser confocal tester and optical contact angle measuring instrument. It was found that the surface texture parameters of different aggregates were quite different. The relative error between the apparent contact angle calculated by the prediction model and the contact angle measured by the test was less than 15 %, indicating that the prediction model had excellent prediction effect. Through the analysis of the wetting model, it is found that the surface tension of the test liquid, the lithology of the solid aggregate, the surface roughness and the texture structure are the important control parameters affecting the wetting. The surface morphology of rough solid can be designed by changing the resolution k and depth H of micropores, so as to control the wettability of solid aggregate surface and epoxy resin aggregate.