Glycerol Water Research Articles

Anomalous behaviour of transport properties in a supercooled water–glycerol mixture

Glycerol acts as a natural cryoprotectant by depressing the temperature of ice nucleation and slowing down the dynamics of water mixtures. In this work, we characterise dynamics – diffusion, viscosity and hydrogen bond dynamics – as well as density anomaly and structure of water mixtures with 1%–50% (w/w) glycerol at low temperatures via molecular dynamics simulations using all-atom and coarse-grained models. Simulations reveal distinct violations of the Stokes–Einstein relation in the low-temperature regime for water and glycerol. Deviations are positive for water at all concentrations, and positive for glycerol in very dilute solutions but turning negative in concentrated ones. The all-atom and coarse-grained models reveal an unexpected crossover in the dynamics of the 1% and 10 % (w/w) glycerol at the lowest simulated temperatures. This crossover manifests in the diffusion coefficients of water and glycerol, as well as in the viscosity and lifetime of hydrogen bonds in water. We interpret that the crossover originates on the opposing dependence with glycerol concentration of the two factors controlling the solutions' slow down: the increase in tetrahedrally coordinated water and the dynamics and clustering of the glycerol molecules. We anticipate that this dynamic crossover will also occur for solution of water with other polyols.

Stable and unstable fall motions of plate-like ice crystal analogues

Abstract. The orientation of ice crystals affects their microphysical behaviour, growth, and precipitation. Orientation also affects interaction with electromagnetic radiation, and through this it influences remote sensing signals, in situ observations, and optical effects. Fall behaviours of a variety of 3D-printed plate-like ice crystal analogues in a tank of water–glycerine mixture are observed with multi-view cameras and digitally reconstructed to simulate the falling of ice crystals in the atmosphere. Four main falling regimes were observed: stable, zigzag, transitional, and spiralling. Stable motion is characterised by no resolvable fluctuations in velocity or orientation, with the maximum dimension oriented horizontally. The zigzagging regime is characterised by a back-and-forth swing in a constant vertical plane, corresponding to a time series of inclination angle approximated by a rectified sine wave. In the spiralling regime, analogues consistently incline at an angle between 7 and 28°, depending on particle shape. Transitional behaviour exhibits motion in between spiral and zigzag, similar to that of a falling spherical pendulum. The inclination angles that unstable planar ice crystals make with the horizontal plane are found to have a non-zero mode. This observed behaviour does not fit the commonly used Gaussian model of inclination angle. The typical Reynolds number when oscillations start is strongly dependent on shape: solid hexagonal plates begin to oscillate at Re =237, whereas several dendritic shapes remain stable throughout all experiments, even at Re > 1000. These results should be considered within remote sensing applications wherein the orientation characteristics of ice crystals are used to retrieve their properties.

FORMULATION AND EVALUATION OF HERBAL TOOTHPASTE

The present study is concerned with the formulation and evaluation of herbal toothpaste, which contains various properties like tooth abrasives, tooth whitening, anti-caring, antibacterial, anti-inflammatory, desensitivity, etc. The herbal toothpaste was prepared using mango leaf extract and guava leaf extract as active ingredients, along with various excipients, which include calcium carbonate, sodium chloride, sodium lauryl sulphate, sodium benzoate, glycerine, camphor, honey and distilled water. The toothpaste was prepared by homogeneous mixing of all the excipients and the herbal extract. Four formulations were prepared using mango leaf extract as an active ingredient along with varying excipient concentrations, four formulations were prepared using guava leaf extract as an active ingredient along with varying excipient concentrations, and a polyherbal formulation consisting of four formulations containing both mango leaf extract and guava leaves extract as active ingredients along with varying excipient concentrations. The formulations were tested for various parameters such as homogeneity, abrasiveness, foamability, moisture content, Spreadability, extrudability, colour, PH, and antibacterial activity. The study concluded that polyherbal formulation showed best results and was found to be best among all batches. The polyherbal formulation, F4 showed was found to be best among all other formulations.

Formulation and Characterization of Emulgel Lornoxicam Containing Lemon Grass Oil as Penetration Enhancer.

Emulgel dosage form is an advanced form of transdermal drug de-livery. It is a combination of emulsion and gel in a definite ratio. Emulsions are incorporated into the gel with proper mixing. The emulsion present in emulgel can be either oil/water or water/oil, which is thickened by mixing it with a gelling agent. On the basis of the solubility of lornoxicam in various oils, a surfac-tant and a co-surfactant were selected for further research. For the preparation of emulgel, the emulsion was prepared with Smix (surfactant and co-surfactant) in a ratio of 1:2. The prepared emulsion was incorporated into different concentrations of carbapol 934 in a 1:1 ratio to make a homogenous emulgel. The emulgel was inspected visually to see if it had any phase behaviour, spreadabil-ity, or grittiness by applying it to a slide. All formulations were evaluated for pH, physical properties, drug content, spreadability, extrudability, swelling index, viscosity, and centrifu-gation. Franz diffusion cell was used to perform in-vitro release of formulation with the help of egg membrane. Among all formulations, F3 showed 83% release after 6 hours and showed acceptable physical properties like homogeneity, colour, consistency, pH value, spreadability, extrudability, and drug content. Thus, emulgel can be regarded as a more feasible drug delivery system for hy-drophobic drugs (lornoxicam) than the currently marketed formulation. Optimized emulgel formulation consists of a microemulsion of lornoxicam, 1 % of carbopol 934, propylene gly-col, sodium benzoate, lemon grass oil, glycerin, and distilled water. In the in-vitro release studies, pH 7.4 phosphate buffer emulgel formulation (F3) showed 83% after 6 hours. Emulgel was found to be stable under stable conditions. The emulgel of the poorly water-soluble drug (lornoxicam) was formulated. The components and their optimum ratio for the formulation of microemulsion were obtained by solubility studies and droplet size analysis. Thus, microemulsion can be regarded as a more feasible dose delivery system for lornoxicam than the currently marketed tablet, capsule, and injection formulations. Optimized microemulsion of lornoxicam was incorporated into the gel base. Therefore, it may be concluded that emulgel of lornoxicam can be used as a controlled-release dosage form of the drug for local application in rheumatoid arthritis.

Effects of Three Different Kinds of Foaming Medium on the Properties of Expanded Thermal Plastic Polyurethane Prepared via Supercritical Carbon Dioxide Foaming.

Hot air, water, and glycerol were studied as foaming mediums for the production of ETPU to evaluate their influence on the behavior of the foam and compare the optimal particles for each of the foaming temperatures selected. The results showed that the times of water foaming and glycerol foaming were shorter by about 2/3 than with hot-air foaming. The best foaming temperatures for hot-air foaming, glycerol foaming, and water foaming are 110-115 °C, 75 °C, and 90 °C, respectively. The particles of glycerol foam have a matte appearance and their gloss is not very good. However, the particles in hot-air foaming are light, and the gloss is very satisfactory. The gloss of the surface of water-foaming particles is dim. At the same time, there is a faint matte appearance. Particles made with glycerol foaming and water foaming are more even than those made with hot-air foaming. The density of foaming materials from glycerol foaming, hot-air foaming, and water foaming are raised accordingly, while the hardness of foaming materials from glycerol foaming, water foaming, and hot-air foaming are successively increased.

Experimental and theoretical investigations of the threshold actuation voltages of aqueous solutions, glycerol–water solutions, and ethanol–water solutions on a coplanar electrode device

In digital microfluidics, actuation voltage is critical in droplet manipulation using electrowetting-on-dielectric. Compared to parallel electrode devices, the droplet manipulation on coplanar electrodes requires a higher actuation voltage due to its structure. This study derives an equation related to the threshold actuation voltage and many critical parameters (applied frequency, surface tension, fluid conductivity, droplet volume, dielectric thickness, etc.). Our developed model has three innovations: (1) liquid and device parameters related to the threshold actuation voltage are integrated into the model, (2) the absolute value of the complex permittivity of the fluid is added into our model to clarify the conductivity-dependent and frequency-dependent threshold actuation voltage, and (3) the extrand model is used to derive the effects of the surface tension, contact angles, and droplet radius on the threshold actuation voltage. Additionally, we used many solutions for biochemical and biomedical assays—DI (Deionized) water, DMEM (Dulbecco's Modified Eagle Medium), PBS (phosphate buffered saline), glycerol–water solutions, ethanol–water solutions, potassium chloride solutions, and sodium chloride solutions—to verify the developed Vth in our model. By using the model and conducting an experiment, we investigated the Vth of different liquids on coplanar electrodes. Our model can successfully explain the difference of Vth between these solutions on coplanar electrode devices. The model and experimental data can be utilized to predict the actuation voltage for a broad range of buffers and organic solvents on coplanar electrodes.

Oxidative and selective C–C cleavage of glycerol to glycolaldehyde with atom-like Cu on Cu-TiO2: Photocatalytic water reduction with concurrent glycerol oxidation in sunlight

Concurrent consumption of electrons and holes for the conversion of a biomass component to value added products represents a highly efficient and sustainable approach towards utilizing renewable energy, but difficult to achieve. The integration of hydrogen production with glycerol oxidation presents a novel and sustainable approach towards achieving a circular economy. In the current study, integration of atom-like Cu-clusters onto TiO2 substrate has been achieved using a facile photo-deposition technique (TC-PDO). Also, novel synthetic approaches have been employed to augment the surface coverage of Cu on TiO2 with atom-like clusters of Cu, either by borohydride treatment on TiO2 followed by Cu-deposition (TC-200) or oxygen-vacancy creation by UV illumination followed by Cu-deposition (TC-PDO). Increased dispersion and enhanced electronic integration of Cu with TiO2 lead to a corresponding increase in the efficiency of photocatalytic hydrogen evolution (13.8 mmol/h.g for TC-PDO at pH 9). Several atom-like Cu integrated with each TiO2 particle acts as photocatalytic reactor, and the same enhances electron-hole separation as well as activity. Sustainable aspect was also studied for TC-PDO up to 25 h at pH 9. Concurrently, glycerol oxidation displays the highest selectivity to C2 product (glycolaldehyde with 70 %) with a C–C cleavage. The investigation of this process holds significant potential for the extensive and simultaneous exploitation of electrons and holes in order to achieve water splitting and glycerol oxidation towards selective value-added products formation.

Coupled CFD-DEM simulation of pin-type wet stirred media mills using immersed boundary approach and hydrodynamic lubrication force

Qualitative description of stressing energies between grinding beads/media in wet stirred media mills at different operation settings could provide a comprehensive understanding of the process parameter influence. In the current work, a modeling approach for wet stirred media mills is described, employing a coupled CFD-DEM framework. This study employs an immersed boundary methodology to emulate the pin-type stirrer rotation in CFD and utilizes a hydrodynamic lubrication force to model the squeezing out and sucking in of fluid between two grinding bead surfaces. The results indicate the influence of process parameters such as the stirrer rotation speed, bead diameter, and bead filling degree. Key findings include the necessity of coupled CFD-DEM with lubrication (i.e., comparison of results from DEM, and coupled CFD-DEM simulations). Dependence of system dynamics on the fluid properties is numerically analyzed using the properties of water–glycerol mixtures.

Preclinical evaluation of the individualized approach for chronic non-healing wounds management

Chronic non‑healing wounds (CNHW) are very common and often incorrectly treated, the morbidity and associated costs of chronic wounds management highlight the need to implement wound prevention and treatment concepts. Objective — to evaluate the possibility of different metal nanooxide polymer nanofilms use for CNHW’ local treatment. Materials and methods. The study design is based on evaluation of various types of dressing materials considering their option for use in CNHW local treatment. Samples of biodegradable polymer films (with an optimal composition of gelatin, polyvinyl alcohol, lactic acid, glycerin and distilled water) saturated with nanoparticles of several oxides with expected antibacterial and pro‑regenerative feature — nZnO, nMgO in concentrations of 1%, 5%, and 10% were used in the study of antimicrobial action and substance release profiling. Quarterly ammonium antiseptic decamethoxin 0.02% was used for control. Results. Obtained data shows that polymer based biodegradable films incorporating optimal component composition (gelatin, polyvinyl alcohol, lactic acid and glycerin) enriched with 5% and 10% zinc nanooxide have potent antimicrobial activity against both gram‑positive and gram‑negative microorganisms, the most common causative agents of CNHW’s. The ion release capacity analysis showed that the Zinc impregnated wound‑healing biodegradable polymer film gradually releases the active substance in a time dependent manner, and the nano‑sized particles of nanoZinc oxide are released from the polymer composition faster than ordinary zinc oxide. Conclusions. Complex natural biodegradable polymer based nanofilms are composite materials impregnated with metal nanooxides showing high potential in local treatment of chronic non‑healing wounds. Polymer film with 5% nanoZnO showed up to the 58% higher antimicrobial activity, comparable or exceeding the one of quarterly ammonium compound decamethoxin. Furthermore, nanoZnO impregnated polymer films compared to standard ZnO impregnated polymer films showed up to 63.2% faster substance release profile with rapid and more unified curve.

Fabrication of a durable corrosion-resistant superamphiphobic CeO2–TiO2 ceramic nanocomposite coating on AZ31B Mg alloy by plasma electrolyte oxidation

A liquid-repellent and corrosion resistant surface was fabricated on AZ31B Mg alloy by the usage of CeO2 and TiO2 nanoparticles (NPs), plasma electrolyte oxidation (PEO) method, and subsequent surface modification. The whole process included two main steps: a) applying PEO with CeO2–TiO2 NPs on AZ31B and b) decreasing surface energy by using a fluorinating agent. Elements that were present on the surface were investigated by XRD and EDS analyses. Surface morphology and its roughness were scrutinized by FESEM images and AFM tests, respectively. Contact angles (CA) of water and some oils (Ethylene glycerol and Glycerol) on the prepared surface were measured. CAs of water and ethylene glycerol were reported at 175.6° and 151.4°, respectively. Also, the corrosion behavior of the prepared surface was assessed by EIS and potentiodynamic polarization analyses. Results showed that the corrosion rate of the neat AZ31B decreased noticeably from 127.78 to 0.027 mpy for superamphiphobic PEO-NPs AZ31B. The prepared sample showed high mechanical durability, which was scrutinized by water floatation, abrasive with grit SiC paper, adhesive tape peeling, and bending tests. After immersion of the sample in 5 wt% NaCl solution for various hours, results showed that the prepared sample had a noticeable corrosion resistance stability.

Comparison of Newtonian and glycerol-water solution-based SiO2 nanofluid droplets impacting on heated spherical surfaces

The dynamic interactions of liquid droplets with heated spherical particles, relevant across various scientific and engineering disciplines, display intriguing collision behaviors whose principles are yet to be fully deciphered. This investigation utilizes high-speed photography to explore the wetting and non-wetting responses of different Newtonian and glycerol-water solution-based SiO2 nanofluid droplets upon contact with heated particles. Findings indicate that nanofluid droplets disrupt the thermal field and modify the surface morphology of particles more extensively under wetting than non-wetting conditions. Wetting conditions lead to significant alterations in the liquid film thickness and notable velocity field disruptions for droplets of deionized water and glycerol solution. Conversely, in the non-wetting phase, droplets nearing full rebound cause less disturbance to the velocity field, a behavior consistent across all fluid types and particle temperatures. The shape changes nanofluid droplets undergo when rebounding and separating from the particle surface are similar to those seen in glycerol solution and water droplets. Droplets in the breakup-rebound phase experience shorter contact times than those merely rebounding. A phase diagram is presented, detailing wetting (receding-deposition and boiling-breakup) and non-wetting (rebound and breakup-rebound) actions. An increase in the Weber number necessitates a higher particle temperature for the transition from rebound to breakup-rebound, which corroborates with theoretical insights. Furthermore, droplets achieve their maximum spreading area during the boiling-breakup mode.

Synthesis of calcium sulfate hemihydrate whiskers from high-purity salt gypsum in a glycerol–water solution at atmospheric pressure

Calcium sulfate hemihydrate whiskers (CSHWs) were prepared from high-purity salt gypsum in a glycerol–water system. The effects of the glycerol/water ratio, reaction temperature, reaction time, and stirring speed on the crystal morphology of the CSHWs were investigated. Results showed that the average length and average length/diameter (L/D) ratio of the CSHWs first increased and then decreased as the glycerol/water ratio, reaction time, and stirring speed were increased, but they continued to gradually increase with increasing reaction temperature. The CSHWs had the highest L/D ratio and smooth surfaces—with an average length of 42.91 μm, an average diameter of 0.72 μm, and an average L/D ratio of 55—when the preparation conditions were a glycerol/water ratio of 2.0, a reaction temperature of 100 °C, a reaction time of 2.0 h, and a stirring speed of 300 rpm. This study provides a feasible idea for the treatment of salt gypsum, which achieves high value-added utilization of salt gypsum as well as the elimination of solid waste.

The dynamics of vertical coalescence of acoustically levitated droplets

Mobility manipulation of liquid droplets is an important task of digital imicrofluidics. Acoustic levitation has revolutionised the contactless manipulation of liquid droplets for various applications. Acoustic levitation technique can be effectively used to manipulate droplets to obtain their coalescence. This paper reports a unique, versatile, and material-independent approach for the vertical coalescence of the droplets suspended in an acoustic levitator. The acoustic power of the levitator is carefully engineered to obtain vertical coalescence of two liquid droplets. Water, 20% and 40% glycerol–water solutions are used as the working liquids. The results of the experiments revealed three outcomes during the coalescence. The outcomes are analysed and discussed.

Improved length of calcium sulfate crystal seeds and whiskers via ball milling and hydration treatment

Elucidating the effect of growth periods on the quality of calcium sulfate whiskers (CSWs) prepared from calcium sulfate dihydrate (DH) is imperative. Herein, crystal seeds and whiskers were prepared from DH in a water–glycerol system. Longer whiskers were obtained from crystal seeds prepared via hydration of DH for 30 s than via ball milling for 5 min followed by hydration for 20 s. The attachment of cetyltrimethyl ammonium bromide and glycerol additives to the whisker tops promoted whisker growth. The whisker sponges exhibited good thermal barrier properties and compression cycle stability.

Transient Phenomena of Dynamic Contact Angle in Micro Capillary Flows

This study is devoted to investigating the dynamics of liquid driven by capillary force in a circular tube. A microscope was used to visualize the meniscus movement and the contact angle. The experiments were carried out with glycerin–water mixtures with viscosity ranging from 0.21 to 1.36 Pa∙s by filling the test liquid in a borosilicate glass tube with an inner diameter of 200 μm. The wetting distances of the meniscus with time were compared with the theoretical solution by considering the dynamic variation of contact angle. The results show that the theoretical solution agrees well with experimental data due to the reflection of the actual dynamic contact angle for the transient motions in the developing entrance region. In view of momentum balance, variations of dominant force according to the time were determined by separated inertial periods, such as inertial, inertial-viscous, and viscous time stages.

Use of natural deep eutectic solvent (NADES) as a green extraction of antioxidant polyphenols from strawberry tree fruit (Arbutus unedo L.): An optimization study

Strawberry tree fruits (Arbutus unedo L.) are being studied as an underutilized wild fruit, rich in various bioactive compounds, especially polyphenols. The main objective of this study was to optimize the extraction process using a natural deep eutectic solvent (NADES) to obtain the highest polyphenol content and antioxidant activity of strawberry tree fruits as determined by different in vitro assays (DPPH, FRAP and ABTS). For this purpose, extraction with NADES was performed in three steps. Among twenty different NADES systems screened for extraction in the first step of solvent screening, two solvents that gave the best results (N6: Betaine–glycerine–water with a molar ratio 1:2:1 and N9: Choline chloride–glycerine with a molar ratio 1:2) were screened in the next step. For these two solvents, two separate Face-centered central composite designs with S/L ratios (10–20-30 g NADES/g sample), temperature (40–55-70 °C), and extraction time (60–120-180 min) were used by response surface methodology (RSM), with total phenolic content and antioxidant activity as the target responses. Based on the software multi-response optimization prediction, the optimal conditions for N6 and N9 were: 1:30 S/L ratio, 65 °C temperature and an extraction time of 150 min, and 1:20 S/L ratio, 56 °C and 180 min, respectively. The optimal parameters were verified experimentally and the main polyphenols were quantified by HPLC-DAD.

Formulation and Evaluation of Formalin Washer Fluid Preparation from Garlic Peel Waste (Allium sativum L.)

Until 2022, there will still be many salted anchovies that contain formalin. This potential danger can be reduced by reducing the levels of formalin that may be contained in salted anchovies before consumption, one of which is by utilizing the saponin content in garlic peel waste. Garlic peel waste powder is proven to be able to reduce formalin levels in salted anchovies by up to 89.12%. However, the use of powder is less practical, and in a certain period, the powder can rot and emit an unpleasant odor. Therefore, an innovation is needed to transform the powder form into a formalin washer fluid. This study aims to determine the effect of garlic peel extract variation on several parameters evaluating the physical properties of formalin washing liquid. The extraction of garlic peel was done using the maceration method and a 70% ethanol solvent. Washing liquids were prepared using glycerin, PEG400, EDTA, and distilled water with varying extract concentrations. Evaluation of physical properties included organoleptic, pH value, specific gravity, viscosity, clarity, and physical stability of formalin washer fluid. The stability test of the physical properties of the sample liquid was carried out using the cycling test method. The samples were kept in storage conditions with extreme temperatures for 3 cycles. In each cycle, the test preparation was stored for 24 hours at 4±2oC and 24 hours at 40±2oC. The formalin washer fluid produced was in the form of a liquid with a weak to pungent garlic aroma, yellow to dark brown in color, homogeneous, clear, and had a pH value of 4. The more extract is used in the formalin washer fluid, the darker the color and the more pungent the garlic aroma will be. Increasing the concentration of garlic peel extract does not affect the pH and clarity of the preparation. The higher the concentration of extract is, the higher the specific gravity and viscosity will be. The selected formula is the formula with a 1% concentration of garlic peel extract.

Experimental study on the surface wave mode of a liquid film under the coupling effect of acoustic oscillation and electric field

This paper conducted an experimental study of a charged liquid film subjected to the coupling effect of acoustic oscillations and an electrostatic field perpendicular to the plane. The experimental system was established. Three different substances—de-ionized water, ionized liquid (BMIMBF4), and a 50 wt. % glycerin–water solution—were utilized to form the liquid film. An oscillator was employed to generate the acoustic oscillations, while the electrostatic field was produced by a high-voltage power supply. Both the increase in oscillating frequency and electric field intensity were observed to alter the surface waveform and elevate the surface wavenumber. Furthermore, the experimental findings align qualitatively with the previously established theoretical results.

Some experimental results for converging flow of dilute polymer solution

This paper presents the results of experimental studies of the flow of a dilute polymer solution in a converging pipe. Three geometries with restriction rates are considered: 2.41, 3.92, and 5.65. A water–glycerin solution of 0.1% polyacrylamide was used as a working fluid. Point velocity measurements are made by using the smoke image velocimetry technique, which previously was proved by the construction of velocity profiles corresponding to the laminar viscoelastic flow in a straight pipe. The influence of the Weissenberg number and the restriction rate of the channel on the velocity profiles are established for both transverse and longitudinal directions. For small Weissenberg numbers, the experimental results are compared with the numerical results obtained using the Giesekus and exponential form of Phan-Thien–Tanner rheological models. Three flow regimes are identified: flow without vortex, vortex enhancement, and divergent flow, which is consistent with published results on the abrupt contraction and converging flows. Vortex length for a wide range of Weissenberg numbers is well predicted by a logarithm function. Modified expression of stretch rate with location of detachment plane can predict the flow regimes and the onset of unsteady flow in converging channels.

Charge Transfer Quenching and Maximum of a Liquid-Air Contact Line Moving over a Hydrophobic Surface.

Charge transfer when a hydrophobic fluoropolymer surface comes in contact with salt solutions of water, methanol, and glycerol is investigated. It is found that the charge transfer decreases faster with an increasing fraction of glycerol in water than it does with methanol in water. It is also demonstrated that for both mixtures, the charge transfer increases with the amount of added sodium chloride for small concentrations but then reaches a maximum and subsequently decreases. Surprisingly, this maximum charge transfer shifts toward higher salt concentrations with increasing amount of glycerol in water. However, in water-methanol mixtures, one does not observe a similar shift in charge transfer maximum toward higher salt concentrations. These observations are explained using a model, taking into account the decreased shear distance from the hydrophobic surface for which ions are removed from the electrical double layer due to an interplay of forces acting on the ions.