Glycerol Water Research Articles

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.

Elucidating the Quenching Mechanism of Tris(2,2'-bipyridyl)ruthenium(II) Complex in the Water-Glycerol Binary System Based on the Microscopic Structure of the Media.

Kinetic studies on the photochemical quenching reaction of the tris(2,2'-bipyridyl) ruthenium(II) complex ([Ru(bpy)3]2+) in water-glycerol binary media were conducted based on the Einstein-Smoluchowski (E-S) theory. Dynamic and static quenching behaviors were analyzed by comparing results from time-resolved spectroscopy and emission spectroscopy. While the dynamic quenching reaction aligns well with the E-S theory, static quenching was observed, leading to a notable increase in the overall photoquenching reaction rate constant. Employing chromatography and infrared spectroscopy, we correlated the microscopic molecular structure of the binary solvent system and the solvation environment around the emitters with the reaction mechanism. This correlation was found to correspond to ion pair formation and the confinement effect of the emitter, respectively.

Effect of the gellan-based edible coating enriched with oregano essential oil on the preservation of the ‘Tardivo di Ciaculli’ mandarin (Citrus reticulata Blanco cv. Tardivo di Ciaculli)

Mandarin, a globally recognized fruit esteemed for its nutritional content and bioactive compounds, as well as aromatic qualities, faces the critical challenge of post-harvest shelf life impacting its marketability and appeal to consumers. This study aims to assess the efficacy of edible coatings in preserving “Tardivo di Ciaculli” mandarin (Citrus reticulata Blanco cv. Tardivo di Ciaculli). Two distinct edible coating formulations, denoted as EC1(comprising gellan gum, glycerol, calcium chloride, and distilled water) and EC2 (comprising gellan gum, glycerol, calcium chloride, distilled water, and 2% oregano essential oil), were subjected to comparative analysis against control samples (CTR). In the experimental trial, mandarin fruits were immersed in the respective edible coating solutions for approximately 5 min and promptly stored at 6 ± 1°C. Qualitative, nutraceutical, microbiological, and sensory analyses were conducted throughout the cold storage period (7, 14, and 24 days at 6 ± 1°C) and during three distinct shelf-life phases (I shelf-life: 7 days at 6 ± 1°C plus 7 days at 15 ± 1°C; II shelf-life: 14 days at 6 ± 1°C plus 7 days at 15 ± 1°C; III shelf-life: 24 days at 6 ± 1°C plus 7 days at 15 ± 1°C). Chemical analysis of the oregano essential oil in EC2 revealed the presence of 27 compounds, with carvacrol being the predominant chemical, constituting 83.42% of the total oil. The findings indicate that the application of edible coatings effectively preserved the quality parameters of mandarin fruits, minimizing weight loss and water loss. Notably, the microbiological analysis, using a culture-dependent approach, demonstrated that EC2, incorporating oregano essential oil, exhibited the capability to diminish the viability of molds throughout the entire study duration, thereby extending the shelf life of mandarin fruits.

Waterproofing a Thermally Actuated Vibrational MEMS Viscosity Sensor

An efficient and inexpensive post-process method to waterproof an electrically actuated microtransducer has been studied. The electrical signals of microtransducers operating in electrically conductive fluids must be effectively isolated from the surrounding environment while remaining in contact for sensing purposes. A thermally actuated MEMS viscosity sensor uses electrical signals for both actuation and sensing. Three post-processing materials, (1) Parylene-C, (2) flouroacrylate-based polymer, and (3) nitrocellulose-based polymer, were coated as thin layers of waterproofing materials on different sensors. All three coating materials provided adequate protection when tested under normal operating conditions. Although the vibration response of the sensors was slightly modified, it did not affect their functionality in a significant way when measuring conductive fluids based on glycerol–water mixtures. All the treated sensors lasted over 1.2 million actuations without any decay in performance or failures. When the test bias conditions were increased by 5x to accelerate failures, the flouroacrylate-based polymer samples lasted 2x longer than the others. Visual analysis of the failures indicates that the edge of the diaphragm, which undergoes the most significant stress and strain values during actuation, was the location of the mechanical failure. This work guides post-processed waterproofing coatings for microscale actuators operating in harsh and damaging environments.

Effect of glycerol incorporation on the liquid crystal structure of sucrose fatty acid ester in aqueous solution

A series of homogeneous samples with high sugar-surfactant content (sucrose fatty acid ester/water and sucrose fatty acid ester/glycerol/water systems) were prepared with well-controlled processes and investigated by DSC, polarized microscopy, X-ray scattering and rheology. Meanwhile the accuracy of the preparation process is confirmed gas chromatography. The polarized microscopy indicates that the ordering degree of the network structure composed of the liquid crystals may be reduced by the glycerol addition. The results of DSC revealed that 50% glycerol solution could significantly inhibit the crystallization of sucrose fatty acid ester and resulted in a significant widening of the temperature interval for the transformation of the liquid crystal phase into the gel phase. In order to further evaluate the effect of glycerol molecules versus water molecules on the liquid crystal structure of sucrose fatty acid ester, we comparatively analyzed the X-ray scattering data from two perspectives: the mass fraction and molar fraction. It was found that 50% glycerol solution could inhibit the crystallization of sucrose fatty acid ester through changing the water-head group interaction of surfactant, facilitates the integration of sucrose fatty acid ester with different alkyl chain length and may reduce the regularity of liquid crystal, both from the perspective of surfactant mass and molar fraction. Furthermore, the addition of 50% glycerol (w/w) does not significantly impede the liquid crystal formation of sucrose fatty acid ester in aqueous solution. However, from the perspective of surfactant mass fraction, glycerol incorporation could reduce the effective cross-sectional areas of the hydrophilic part of sucrose fatty acid ester in aqueous solution and induce the phase transition of hexagonal liquid crystals to aggregates with less positive curvature, while an opposite tendency could be obtained from the perspective of surfactant molar fraction. The conclusions are also confirmed by subsequent rheological test. Moreover, the results of rheological measurements reveals that the interactions among cylindrical units of the hexagonal liquid crystalline phase become weaker and the surfactant molecules aggregate more loosely in the cylindrical unit with the glycerol incorporation. Moreover, the above-mentioned influence of glycerol on the liquid crystal structure of sucrose fatty acid ester in aqueous solution would be similar but more prominent from the perspective of the molar fraction.

The study of perspective medicinal plants using the example of Helianthus tuberosus L.

This paper presents the results of microscopic analysis of a perspective medicinal plant Helianthus tuberosus used for the treatment of diabetes mellitus. The study was conducted to identify specific morphological and structural characteristics of this plant, which may have a positive impact on the efficacy and safety of its use for medical purposes. Different types of plant material were used in the research: fresh plants, dried plant material and preserved plant material. For preservation of the latter, a special mixture consisting of ethyl alcohol, glycerol and distilled water in equal volumes was used. Anatomical study of the structure and structure of plants was carried out using several methods: to study the structure of the epidermis, surface samples were prepared, which allowed us to get a detailed idea of the cellular composition and location of the epidermis on the surface of leaves, stems and roots of plants; for a deeper study of the internal structure of plants, transverse sections were made, which were further investigated. The results of the study suggest the high potential of this plant as a basis for the development of safe and effective phytopreparations.

Formulasi Dan Stabilitas Fisik Krim Ekstrak Daun Kelor (Moringa Oleifera Lamk) Dengan Perbedaan Humektan

One of the medicinal plants used as traditional medicine is kelor (Moringa oleifera Lamk). Moringa leaves are rich in vitamin C and antioxidants which can increase collagen production to prevent and slow down premature aging. The effect of humectants on cream preparations is to obtain creams that have good physical characteristics during storage. This study aims to determine the formulation and physical stability of moringa leaf extract cream preparations (Moringa oliefera Lamk) that meet the requirements. The variations of humectants used in this study include propylenglycol-glycerin (FI), glycerin (FII) and propylenglycol (FIII). Stearic acid, cetyl alcohol (oil phase) were melted on a water bath, TEA, methylparaben, propylparaben, glycerol and distilled water (water phase) were heated. The two phases gradually and grind to form a creamy mass and add the extract. Test the physical quality of the cream for 1 week, namely organoleptic test, homogeneity test, pH test, spreadability test and viscosity test. The results of the cream spreadability test of Moringa leaf extract (Moringa oleifera Lamk) in formula I did not meet the requirements, formula II produced cream preparations that met the requirements with a spreadability range of 5-6 cm, formula III did not meet the requirements. The results of the viscosity test on the formula I, II, III are in the range of 22000-30000 cPs. Based on the results of research on formula II with the addition of the humectant glycerin, it produces a good cream preparation.

Pinching dynamics and extensional rheology of dense colloidal suspensions with depletion attractions

We study the extensional flow properties by characterizing the capillarity-driven pinching dynamics of dense colloidal suspensions at a constant volume fraction ϕ=0.40 with polymer-induced depletion interactions using a dripping-onto-substrate (DoS) protocol. Methacrylate copolymer particles with dimethylacrylamide copolymer brushes are suspended in a refractive-index- and density-matched mixture of 80 (w/w)% glycerol in water with NaCl added to screen the electrostatic repulsions. Depletion attractions between the colloids are introduced by adding polyacrylamide polymers of weight and dispersity. The addition of polymer delays and modifies the pinch-off dynamics of the dense suspensions, depending on the size and dispersity of the polymer. The extensional relaxation time λE of suspensions collapses as a function of the normalized free volume polymer concentration c/c∗ with the corresponding polymer solutions, indicating that the elastic properties of the polymer solutions control the extensional time scale. Following the results of our previous study [Soetrisno et al., Macromolecules 56, 4919–4928 (2023)], the polymer size determines the scaling exponent of λE for colloid-polymer mixtures in the dilute regime and high dispersity shifts the concentration where the scaling of λE transitions from power-law to linear. The filament lifespans tf of colloid-polymer mixtures and of polymer solutions collapse onto a master curve as a function of c/c∗ when normalized by the filament lifespan of the corresponding fluid without polymer tf,0. These results provide insight into the role of the polymer size in dictating the pinching dynamics and extensional rheology of colloid-polymer mixtures and further suggest that the shear and extensional responses of these mixtures can be separately tuned through the concentrations of the two constituents.

Simulation of Supercritical Water Gasification Reaction of Glycerol and Reactor Structure Study

The study established a reactor model with a volume of 500 ml that can withstand high temperature and high pressure, and firstly used the simulation software ANSYS FLUENT 2023R1 to simulate the process of generating H2-rich gaseous products by reacting glycerol in supercritical water at a temperature of 374°C and a pressure of 23 Mpa, and the results showed that the pressure and temperature were uniformly distributed in the fluid domain of the reactor. The results show that the pressure and temperature are uniformly distributed in the fluid domain of the reactor. Secondly, according to the pressure distribution obtained from the simulated reaction, the transient dynamics and thermo-mechanical coupling field analysis were applied to the inner wall of the reactor cavity in ANSYS Workbench to study the stress displacement. Finally, the results of the two analyses are compared to conclude that the pressure field can affect the trend of stress and displacement of the reactor structure, and the temperature field at higher temperatures can increase the values of stress and displacement.

Energy exchange during the early phase of droplet impact onto a dry surface

This study investigates droplet impact dynamics on a rigid substrate using droplets of water and water–glycerol mixtures. Experiments are conducted in the Weber number range of 179–929, and the corresponding Reynolds numbers are in the range of 5253–12 090. The profile of the droplet interface is studied. Assuming self-similarity in the internal flow at the interface of the droplet, the profiles are scaled using appropriate scales. It is observed that the profiles of the droplet interface (at different points of time) collapse close to each other when plotted in this manner. This observation serves as an experimental evidence to the self-similarity of the internal flow in this phase. Based on this fact, we make an estimate of kinetic energy at early stages of droplet impact. The surface energy is also estimated by assuming axisymmetry in the droplet profile obtained through back-light imaging. We observe that a considerable amount of the kinetic energy is lost during the early stages of droplet impact. We believe that an accurate estimation of this deficit in kinetic energy at an early stage of impact will be necessary to account in the energy based models for droplet impact.

Meta-Heuristic Optimization and Comparison for Battery Pack Thermal Systems Using Simulink

This study examines the use of meta-heuristic algorithms, specifically particle swarm optimization and genetic algorithms, for optimizing thermal systems, addressing a research gap on their efficacy in larger systems. Utilizing MATLAB’s Simulink and Simscape, the research initially targets an electric vehicle thermal system model, emphasizing the optimization of a Li-ion battery pack and associated cooling components, like chillers, pumps, and cooling plates, during operation. One consideration is the use of a glycerol–water mixture in the chiller pump, which demands the use of an optimal control algorithm that adjusts to outdoor temperatures and control strategies. This study focuses on computational efficiency reflecting the complexity of system simulations. Challenges related to applying particle swarm optimization and genetic algorithms to these systems are scrutinized, leading to the establishment of a new objective function to pinpoint target values for system optimization. This research aims to refine design methodologies for engineers by harmonizing optimal design with computational expediency, thereby enhancing the engineering design process in thermal management. This integrative approach promises to yield practical insights, benefiting engineers dedicated to the advancement of thermal system design and optimization. The results show that, compared to the base model, 1% of the overall state of charge could be saved, and the battery temperature could also be cooled by more than 4 °C compared to the initial temperature.

On the settling of aligned spherical particles in various quiescent media

We investigated experimentally the settling behaviour of vertically aligned spherical particles within various quiescent media at different release frequencies. The particles had a diameter of $d = 4$ mm and density of $\rho _s = 2200$ kg m $^{-3}$ , and were released near the free surface of water, ethanol, a G60 water–glycerine mixture (60 % glycerine by weight) and oil media at frequencies of $f_P = 4$ , 6 and 8 Hz, thereby allowing study of Galileo numbers, $Ga \in [16, 976]$ . Particle tracking velocimetry quantified the motion of nearly 800 particles in a 600 mm high tank, and particle image velocimetry examined flow patterns around the particles. Results revealed that the centre of mass of the particle trajectories exhibited preferential in-plane motions, with significant lateral dispersion and large $Ga$ in water and ethanol, and nearly vertical paths with low $Ga$ in the G60 mixture and oil media. Varying degrees of particle separation resulted in higher terminal velocities than for a single particle. Hence, particle drag decreased in all cases, with the oil medium showing the highest drag reduction under the closest particle separation, reaching up to nearly 70 % of that for the single particle. The vertical and lateral pair dispersions, $R^2_z$ and $R^2_L$ , exhibited ballistic scaling, with dependences on the initial separation, $r_0$ , and the type of medium. With large $Ga$ , $R^2_z$ displayed a ballistic regime followed by a slower rate, whereas with small $Ga$ , $R^2_z$ maintained a consistent ballistic regime throughout settling. Finally, normalized $R^2_z$ demonstrated distinct scaling (exponent 2/3 and 1) dependent on the normalized initial separation and $Ga$ .

Highly stretchable anti-freeze hydrogel based on aloe polysaccharides with high ionic conductivity for multifunctional wearable sensors

Conductive hydrogels have limitations such as non-degradability, loss of electrical conductivity at sub-zero temperatures, and single functionality, which limit their applicability as materials for wearable sensors. To overcome these limitations, this study proposes a bio-based hydrogel using aloe polysaccharides as the matrix and degradable polyvinyl alcohol as a reinforcing material. The hydrogel was crosslinked with borax in a glycerol–water binary solvent system, producing good toughness and compressive strength. Furthermore, the hydrogel was developed as a sensor that could detect both small and large deformations with a low detection limit of 1 % and high stretchability of up to 300 %. Moreover, the sensor exhibited excellent frost resistance at temperatures above −50 °C, and the gauge factor of the hydrogel was 2.86 at 20 °C and 2.12 at −20 °C. The Aloe-polysaccharide-based conductive hydrogels also functioned effectively as a wearable sensor; it detected a wide range of humidities (0–98 % relative humidity) and exhibited fast response and recovery times (1.1 and 0.9 s) while detecting normal human breathing. The polysaccharide hydrogel was also temperature sensitive (1.737 % °C−1) and allowed for information sensing during handwriting.

Effect of Running-In Conditions on the Super Low EHD Sliding Friction of Si3N4 Ball and WC Plate in Glycerol–Water Solution

Effect of Running-In Conditions on the Super Low EHD Sliding Friction of Si3N4 Ball and WC Plate in Glycerol–Water Solution

Evaluation of the Biological Activity of Hydrogel with Cornus mas L. Extract and Its Potential Use in Dermatology and Cosmetology.

Due to the growing popularity of herbal extract-loaded hydrogels, this study assessed the biological activity of extracts and hydrogels containing three types (water (WE), water-ethanol (EE) and water-glycerin (GE)) of Cornus mas L. (dogwood) extracts. The content of biologically active compounds in the extracts was assessed using the UPLC-DAD-MS technique. Antioxidant properties were assessed by using DPPH and ABTS radicals and measuring the intracellular level of reactive oxygen species. Alamar Blue and Neutral Red tests were used to measure the cytotoxicity of the tested samples on skin cells-fibroblasts and keratinocytes. Cell migration and the anti-aging activity of the tested extracts and hydrogels were assessed. Transepidermal water loss and skin hydration after applying the hydrogels to the skin were also determined. A chromatographic analysis revealed that the extracts contained polyphenols, including gallic, caftaric, protocatechuic, chlorogenic, ellagic and p-coumaroylquinic acids, as well as iridoids, with loganic acid as the predominant component. Additionally, they contained cyanidin 3-O-galactoside, pelargonidin 3-O-glucoside and quinic acid. The obtained results show that the tested extracts and hydrogels had strong antioxidant properties and had a positive effect on the viability of skin cells in vitro. Additionally, it was shown that they stimulated the migration of these cells and had the ability to inhibit the activity of collagenase and elastase. Moreover, the tested hydrogels increased skin hydration and prevented transepidermal water loss. The obtained results indicate that the developed hydrogels may be effective delivery systems for phytochemicals contained in dogwood extracts.

Solvent-exchange triggered hydrogen bond activation strategy toward self-adaptive strong and tough organohydrogel artificial muscle

Hydrogel actuators have aroused tremendous interests in various fields such as artificial muscles, biomedicine and wearable devices. However, hydrogel actuators face persistent challenges due to their intrinsic weak and hydrophilic networks, which result in brittle and weak mechanical properties after swelling. Here, we proposed a solvent-exchange hydrogen bond activation strategy to fabricate a highly strong and tough self-adaptive organohydrogel actuators (SOA). The glycerol releasing and water retention triggers abnormal swelling of SOA due to the cross-linking of tannic acid (TA) and polyvinyl alcohol (PVA) nanofibrillar network. After the hydrogen bond activation between PVA and TA, SOA shows a denser and porous nanofibrillar network with high tensile strength (5.4 ± 0.2 MPa), high fracture energy (134.9 ± 7.6 kJ/m2), and high toughness (18.5 ± 0.7 MJ/m3). Owing to its good processibility, an anisotropic multi-filament twisted fiber actuator that exhibits ultra-high modulus (83.5 ± 2.6 MPa) and humidity-sensitive actuation performance was developed. The proposed solvent-exchange strategy shows great potential for the rational design and fabrication of bionic strong and tough artificial muscles.

Syngas production from aqueous phase reforming of glycerol–water mixture for compression ignition engine

Syngas produced from glycerol using aqueous phase reforming for nickel-based catalysts with different support materials were tested in a compression ignition (CI) engine. Experiments were conducted using nickel–alumina, nickel–lanthanum (NL), and nickel–ceria catalysts at 1:1, 1:2, 1:3, and 1:4 glycerol–water ratios and temperatures of 240°C, 260°C, and 280°C. The NL catalyst showed the highest syngas and hydrogen yield of 90.58% and 76.42%, respectively, at 1:3 ratio and 260°C. The optimized NL syngas and diesel were tested in a CI engine at 6 to 30 lpm flow rates. At 30 lpm flow, brake thermal efficiency increased by 3.15%, NOx emission was reduced by 21.22%, and smoke lowered significantly compared to diesel. The faster hydrogen combustion in syngas increased the heat release rate and cylinder peak pressure. CO and HC emissions increased at lower loads due to diluted combustion but reduced at higher loads. NL showed the best performance and emissions among the syngases due to higher hydrogen content. In summary, the NL syngas at 30 lpm showed great potential in CI engines by improving combustion and performance and reducing emissions.

The Optimization of Pressure-Assisted Microsyringe (PAM) 3D Printing Parameters for the Development of Sustainable Starch-Based Patches.

The aim of this work was to develop sustainable patches for wound application, using the biopolymer starch, created using a low-cost 3D printing PAM device. The composition of a starch gel was optimized for PAM extrusion: corn starch 10% w/w, β-glucan water suspension (filler, 1% w/w), glycerol (plasticizer, 29% w/w), and water 60% w/w. The most suitable 3D printing parameters were optimized as well (nozzle size 0.8 mm, layer height 0.2 mm, infill 100%, volumetric flow rate 3.02 mm3/s, and print speed 15 mm/s). The suitable conditions for post-printing drying were set at 37 °C for 24 h. The obtained patch was homogenous but with low mechanical resistance. To solve this problem, the starch gel was extruded over an alginate support, which, after drying, becomes an integral part of the product, constituting the backing layer of the final formulation. This approach significantly improved the physicochemical and post-printing properties of the final bilayer patch, showing suitable mechanical properties such as elastic modulus (3.80 ± 0.82 MPa), strength (0.92 ± 0.08 MPa), and deformation at break (50 ± 1%). The obtained results suggest the possibility of low-cost production of patches for wound treatment by additive manufacturing technology.

Kirigami‐Inspired 3D‐Printable MXene Organohydrogels for Soft Electronics

AbstractConductive hydrogels are compelling materials for the development of soft electronics; however, their essential attributes such as high sensitivity, excellent stretchability, and environmental stability have rarely been achieved simultaneously in one hydrogel. Herein, a Kirigami‐inspired strategy is proposed to improve organohydrogel sensitivity without sacrificing their mechanical stretchability and environmental stability . The organohydrogels with multiple interpenetrating networks are synthesized by introducing sodium alginate nanofibrils and conductive MXene nanoflakes into polymer double networks infiltrated with glycerol–water mixtures, featuring remarkable stretchability (>5000%), good sensitivity, and water retention (>30 days). The Kirigami structures are further applied to enhance strain sensitivity, achieving a gauge factor of 29.1, which is ≈5.5 times that of an unstructured organohydrogel. Using the Kirigami‐inspired sensors, a durable glove is developed for grabbing underwater objects through operating a robotic arm, demonstrating a subaqueous interactive human–machine interfacing.Meanwhile, by integrating the wearable sensor with a machine learning algorithm, a wearable Morse code intelligent recognition system is demonstrated, enabling real‐time conversion of Morse code signs into speech with superior recognition accuracy (>99%) and fast response time (≈17 ms). This work offers a new route to synthesize highly sensitive, stretchable, and extremely tolerant organohydrogels, providing a promising platform for next‐generation soft electronics.

Cryogenic-compatible spherical rotors and stators for magic angle spinning dynamic nuclear polarization.

Cryogenic magic angle spinning (MAS) is a standard technique utilized for dynamic nuclear polarization (DNP) in solid-state nuclear magnetic resonance (NMR). Here we describe the optimization and implementation of a stator for cryogenic MAS with 9.5 mm diameter spherical rotors, allowing for DNP experiments on large sample volumes. Designs of the stator and rotor for cryogenic MAS build on recent advancements of MAS spheres and take a step further to incorporate sample insert and eject and a temperature-independent spinning stability of Hz. At a field of 7 T and spinning at 2.0 kHz with a sample temperature of 105-107 K, DNP enhancements of 256 and 200 were observed for 124 and 223 L sample volumes, respectively, each consisting of 4 M C, N-labeled urea and 20 mM AMUPol in a glycerol-water glassy matrix.