Water-based Gels Research Articles

Garlic Inulin as a Fat Replacer in Vegetable Fat Incorporated Low-Fat Chicken Sausages.

Inulin is a non-digestible carbohydrate and a prebiotic that can also act as a fat replacer in various foods. This study examined the effect of replacing vegetable oil with garlic inulin on the quality traits of chicken sausages. Water-based inulin gels were prepared using garlic inulin or commercial inulin to imitate fats in chicken sausages. Chicken sausages were prepared separately replacing vegetable oil with water-based inulin gels to reach final inulin percentages of 1, 2, and 3 (w/w). The control was prepared using 3% (w/w) vegetable oil with no inulin. The physicochemical properties and thiobarbituric acid reactive substance (TBARS) value of prepared sausages were analyzed over 28-d frozen storage. Sausages with 2% garlic inulin recorded higher flavour and overall acceptability scores (p<0.05). Ash, moisture, and protein contents of the sausages were increased with increasing levels of inulin while fat content was reduced from 13.67% (control) to 4.47%–4.85% (p<0.05) in 3% inulin-incorporated products. Sausages incorporated with 2% inulin had lower lightness (L*) values than the control (p<0.05). Water holding capacity (WHC) was similar (p>0.05) among the samples. During storage L* value, pH, and WHC decreased while redness (a*) and yellowness (b*) values increased in all the samples. In addition, TBARS values were increased during the storage in all samples within the acceptable limits. In conclusion, garlic inulin can be used successfully as a fat substitute in sausages without altering meat quality parameters.

Storage Stability of Chilled and Frozen Starch Gels as Affected by Blended Starch Formulation, Sucrose Syrup, and Coconut Milk.

Effects of starch formulation, highly concentrated sucrose solution, and coconut milk on the stability of starch gels kept under chilled and frozen conditions were determined. Gels containing rice starch (RS), tapioca starch (TS) (RS:TS of 1 : 0.85), and hydroxypropyl distarch phosphate (HDP, 0-50% of total starch) were prepared from 15% starch suspension using water, 45°Brix sucrose syrup or coconut milk as liquid media. After aging at 4°C for 21 days, starch gels had higher hardness and chewiness, with lower cohesiveness and springiness (p ≤ 0.05). Water-based gels containing HDP had less extent of texture hardening, lower degree of crystallinity, and more homogeneous microstructure during 4°C aging. However, for the starch gels in sucrose syrup or coconut milk, HDP induced greater gel hardening, higher degree of crystallinity, and denser gel microstructure during chilled storage. This could be due to the crystallization of sucrose or lipid/amylose-lipid complexes. Nevertheless, HDP enhanced freeze-thaw stability of the gels, regardless of the liquid media used (p ≤ 0.05). According to the consumer test of the model desserts subjected to a single freeze-thaw cycle, the sample containing 50% HDP gel in sucrose syrup or 25% HDP gel in coconut milk gained the highest hedonic score of texture and overall acceptance (p ≤ 0.05).

Rheological stability of carbomer in hydroalcoholic gels: Influence of alcohol type.

Rheological stability of carbomer in hydroalcoholic gels: Influence of alcohol type.

Microbicidal effect and storage stability of neutral HOCl-containing aqueous gels with different thickening/gelling agents.

Electrolyzed waters, containing mainly hypochlorous acid, are used in dental practice because of their high microbicidal effect. For wider use, three neutral electrolyzed water-based gels, namely, HOCl-containing aqueous gels were prepared with a thickening/gelling agent in this study. We evaluated their microbicidal effects against four strains and storage stabilities indicated by available chlorine concentration. Immediately after preparation, all gels (70 ppm) could completely remove microbes by a 3-min treatment. The gel prepared with xanthan gum remarkably reduced its available chlorine concentration even under shaded and refrigerated storage conditions, failing to maintain its microbicidal effect following 1-day storage, whereas other gels, prepared with carboxyvinyl polymer or agar, maintained effective concentration (>20 ppm), with high microbicidal effects following 9-day and 21-day storage, respectively. Neutral electrolyzed water-based gels might be useful to remove oral microbes. Based on our results, agar is the most suitable thickening/gelling agent from the viewpoint of storage stability.

Clinical reliability and cost analysis of using petroleum jelly creams versus water-based gels for urethral catheterization

Clinical reliability and cost analysis of using petroleum jelly creams versus water-based gels for urethral catheterization

Research progress on transient hydrogels

Hydrogels are a kind of soft and wet materials, which have three-dimensional network structures formed by polymers or small molecules in water through self-assembly or chemical cross-linking. Hydrogels can be divided into two categories of chemical and physical hydrogels according to the ways of hydrogel formation. The chemical hydrogels containing covalent bonds have high chemical resistance and thermodynamic stability. However, they are usually nondegradable and unrecyclable due to the irreversibility of covalent bonds, which limits their practical application. By contrast, various stimuli-responsive hydrogels based on supramolecular interactions or dynamic covalent bonds have become the research focus in recent years. These studies expand the application of hydrogels in drug delivery, biosensing, shape memory, etc. However, the classical responsiveness of the hydrogels is relatively passive, which always requires an external stimulus to induce the assembly or disassembly of the hydrogel networks and lacks the ability of self-regulation. Self-regulating systems are very common in living organisms, such as the reversible formation of intracellular actin. The non-equilibrium dynamic processes generate transient assemblies, which inspires the researchers to design artificial non-equilibrium systems. In 2010, a transient supramolecular hydrogel mediated by chemical fuels was presented for the first time. In the following decade, the researchers have been exploring how to mimic the living systems by simply mixing chemical reagents to build artificial non-equilibrium systems. The emergence of transient hydrogels is a significant breakthrough in the field of smart hydrogel materials. In the system, a switch that can induce sol-gel transitions autonomously is set up, which endows the soft materials with autonomy or adaptability. The scientists have realized the versatile regulation of the structure, function and lifespan of the hydrogels by imitating the complex living systems and combining the existing biocatalytic and/or chemical reactions. For example, for injectable biomaterials, the precise control on the lifetime of the transient hydrogels contributes to the timed release of drugs. Moreover, the transient hydrogels can also be used as temporary seals or adhesives for biomedical applications. At the same time, the remote-controlled time programmability is of great significance for the in situ study of self-assembly in closed systems. Although the research on transient hydrogels is still in its infancy, the advanced characteristics of the transient hydrogels, as well as the spatiotemporal regulation mode for the precise control of material properties, suggest that the transient hydrogels will be an important class of intelligent soft materials useful in many fields such as drug delivery, data encryption, material repairing and reprocessing in the future. In short, the transient hydrogel systems regulated by the chemical reaction networks are one of the important results inspired from the dissipative assembly in living systems. They significantly broaden the application range of hydrogels. In general, the current research in the field of transient hydrogels mainly focuses on the expansion of transient hydrogel systems and the design of transition modes, which requires a deeper understanding of the hydrogel formation mechanisms. Therefore, it is necessary to make a systematic summary for this rapidly developing field at this point. In this review, we give a clear definition of transient hydrogels: transient hydrogels refer to water-based temporary gels formed in non-equilibrium states, which can spontaneously convert to sol states mediated by internal reactions. According to the difference in hydrogel formation mechanisms, the classification of hydrogels is presented. Furthermore, the existing transient hydrogel systems are reviewed in detail. The application and limitation of transient hydrogels are summarized, and the future development direction is discussed and prospected lastly in this review.

Influence of Hydrogen Bond Donor Identity and Intentional Water Addition on the Properties of Gelatin-Supported Deep Eutectic Solvent Gels.

Deep eutectic solvent (DES) gel electrolytes have recently emerged as promising alternatives to ionic liquid- or water-based gels for "ionic skin" sensor applications. Researchers have also been exploring the effects that varying amounts of water may have on the local hydrogen bonding environment within a few model DES systems. In this study, the physical properties and ionic conductivities of biopolymer (gelatin)-supported gels featuring two established DESs and three DES/water mixture formulations are investigated and compared. The DES/water mixtures are formed by combining choline chloride with one of three organic hydrogen bond donors (HBDs), ethylene glycol, glycerol, or 1,2-propanediol, in a 1:2 molar ratio, together with a controlled amount of water, 25 mol % (approximately 5-6 wt % water). For the same fixed gelatin content (20 wt %), DES/water mixture gel Young's modulus values are found to be tunable based on the organic HBD identity, increasing 6-fold from 7 (1,2-propanediol) to 42 (glycerol) kPa. Furthermore, large differences are observed in the resulting gel properties when water has been intentionally added to well-studied DESs. Coformulation with water is found to increase ethylene glycol-based DES gel toughness, measured via tensile testing, from 23 to 68 kJ/m3 while simultaneously boosting gel room temperature ionic conductivity from 3.3 to 5.2 mS/cm. These results highlight the multiple roles that controlled amounts of water in DES can play within gelatin-supported DES/mixture gel electrolytes, such as influencing gelatin self-assembly and reducing local viscosity to promote facile ion transport.

Non-hormonal vaginal treatment of vulvovaginal dryness symptoms: a 10-year experience using an oil-in-water cream

Vulvovaginal atrophy (VVA), mainly occurs in postmenopausal women, but can also arise in women who experience decreased estrogen levels, e.g. due to breast cancer treatment. According to NAMS guidelines, the primary aim of VVA treatment is to alleviate subjective symptoms using non-hormonal vaginal moisturizers, e.g. creams or water-based gels. In contrast to gels, oil-in water emulsions (creams) have emollient properties by supplying dry and sensitive skin of the vagina and external genital area with moisture and soothing lipids. For symptomatic VVA not responding to this initial therapy, vaginal hormone therapy is indicated. Here, we present data from 10-years of experience regarding the efficacy and safety of VVA subjective symptom treatment using a non-hormonal, vaginal oil-in-water cream (Vagisan MoistCream, Dr. August Wolff Arzneimittel, Bielefeld).

Light-based 3D printing of hydrogels with high-resolution channels

Hydrogels are soft, water-based gels with widespread applications in personal care products, medicine and biomedical engineering. Many applications require structuring the hydrogel into complex three-dimensional (3D) shapes. For these applications, light-based 3D printing methods offer exquisite control over material structure. However, the use of these methods for structuring hydrogels is underdeveloped. In particular, the ability to print hydrogel objects containing internal voids and channels is limited by the lack of well-characterized formulations that strongly attenuate light and the lack of a theoretical framework for predicting and mitigating channel occlusion. Here we present a combined experimental and theoretical approach for creating well-defined channels with any orientation in hydrogels using light-based 3D printing. This is achieved by the incorporation of photoblocker and the optimization of print conditions to ensure layer-layer adhesion while minimizing channel occlusion. To demonstrate the value of this approach we print hydrogels containing individual spiral channels with centimeter-scale length and submillimeter-scale cross-section. While the channels presented here are relatively simple, this same approach could be used to achieve more complex channel designs mimicking, for example, the complex vasculature of living organisms. The low cytotoxicity of the gel makes the formulation a promising candidate for biological applications.

Thermal Slip in Oblique Radiative Nano-polymer Gel Transport with Temperature-Dependent Viscosity: Solar Collector Nanomaterial Coating Manufacturing Simulation

Nano-polymeric solar paints and sol-gels have emerged as a major new development in solar cell/collector coatings offering significant improvements in durability, anti-corrosion and thermal efficiency. They also exhibit substantial viscosity variation with temperature which can be exploited in solar collector designs. Modern manufacturing processes for such nano-rheological materials frequently employ stagnation flow dynamics under high temperature which invokes radiative heat transfer. Motivated by elaborating in further detail the nanoscale heat, mass and momentum characteristics, the present article presents a mathematical and computational study of the steady, two-dimensional, non-aligned thermo-fluid boundary layer transport of copper metal-doped water-based nano-polymeric sol gels under radiative heat flux. To simulate real nano-polymer boundary interface dynamics, thermal slip is analysed at the wall. A temperature-dependent viscosity is also considered. The conservation equations for mass, normal and tangential momentum and energy are normalized via appropriate transformations to generate a multi-degree, ordinary differential, non-linear, coupled boundary value problem. Numerical solutions are obtained via the stable, efficient Runge-Kutta-Fehlberg scheme with shooting quadrature in MATLAB symbolic software. Validation of solutions is achieved with a Variational Iterative Method (VIM) utilizing Langrangian multipliers. The impact of key emerging dimensionless parameters i.e. obliqueness parameter, radiation-conduction Rosseland number (Rd), thermal slip parameter (ALPHA), viscosity parameter (m), nanoparticles volume fraction (PHI) on non-dimensional normal and tangential velocity components, temperature, wall shear stress, local heat flux and streamline distributions is visualized graphically. Shear stress and temperature are boosted with increasing radiative effect whereas local heat flux is reduced. Increasing wall thermal slip parameter depletes temperatures.

Velocity slip in mixed convective oblique transport of titanium oxide/water (nano-polymer) with temperature-dependent viscosity

Nano-polymers are the emerging development in cell coatings due to their enhanced durability and thermal efficiency. The viscosity of such fluids is considerably influenced by temperature. Motivated by fascinating applications of nano-polymers, the present article offers a mathematical study of steady, oblique transport of titanium water-based nano-polymer gels under mixed convection effects. To simulate real nano-polymer boundary interface dynamics, convective surface along with velocity slip are analysed at the wall. Viscosity is assumed to be temperature-dependent in our analysis. The conservation equations for mass, momentum (both normal and tangential) and energy are normalized using appropriate transformations leading to a multi degree nonlinear ordinary differential equations problem. Numerical solutions are attained using the Runge-Kutta-Fehlberg method with shooting quadrature in the symbolic software MATLAB. The influence of key evolving parameters, namely mixed convection parameter, velocity slip parameter, nanoparticles volume fraction on non-dimensional velocity components, temperature, normal and tangential skin friction coefficients and local heat flux is examined. Increasing the velocity slip parameter decreases the velocity components while it increases the temperature. The simulations performed reveal that the normal skin friction coefficient and the heat flux at the wall increase with enhancing the nanoparticles volume fraction.

Carbohydrate gel beads as model probes for quantifying non-ionic and ionic contributions behind the swelling of delignified plant fibers

Macroscopic beads of water-based gels consisting of uncharged and partially charged β-(1,4)-d-glucan polymers were developed to be used as a novel model material for studying the water induced swelling of the delignified plant fiber walls. The gel beads were prepared by drop-wise precipitation of solutions of dissolving grade fibers carboxymethylated to different degrees. The internal structure was analyzed using Solid State Cross-Polarization Magic Angle Spinning Carbon-13 Nuclear Magnetic Resonance and Small Angle X-ray Scattering showing that the internal structure could be considered a homogeneous, non-crystalline and molecularly dispersed polymer network. When beads with different charge densities were equilibrated with aqueous solutions of different ionic strengths and/or pH, the change in water uptake followed the trends expected for weak polyelectrolyte gels and the trends found for cellulose-rich fibers. When dried and subsequently immersed in water the beads also showed an irreversible loss of swelling depending on the charge and type of counter-ion which is commonly also found for cellulose-rich fibers. Taken all these results together it is clear that the model cellulose-based beads constitute an excellent tool for studying the fundamentals of swelling of cellulose rich plant fibers, aiding in the elucidation of the different molecular and supramolecular contributions to the swelling.

Novel development of 3D printable UV-curable silicone for multimodal imaging phantom

Medical imaging is an effective medical technique used to diagnose the cancer and other diseases. To optimize medical imaging, a calibration medium or phantom with tissue-mimicking properties is required. A phantom is a specially engineered object that is used in calibration or tuning of the medical imaging modalities, specifically Magnetic Resonance Imaging (MRI) and Computed Tomography (CT). Most of the phantoms investigated were fabricated with water-based polymer gels such as carrageenan, agar, and poly(vinyl alcohol). However, due to water content fluctuation, the stability of the relaxation times, T1 and T2, are problematic. Therefore, there is a demand for the development of phantoms fabricated from solid material without stability issues. Furthermore, there are potential applications of phantoms as surgical planning tools for health practitioner training. In this study, we fabricated Ultraviolet (UV)-curable silicone with various concentrations of water and hydrophilic silicone content to investigate its mechanical and imaging properties. The results demonstrate that the silicone cures faster with addition of water within 30s to be applicable for 3D printing. Imaging properties for ultrasound, MRI and CT also demonstrated improvement with addition of water content. With optimal properties, silicone can be used to fabricate the phantom using 3D printing technique.

Mathematical modeling of a non-Newtonian fluid flow in the main fracture inside permeable porous media

This paper describes a mathematical model of the main fracture isolation in porous media by water-based mature gels. While modeling injection, water infiltration from the gel pack through fracture walls is taking into account, due to which the polymer concentration changes and the residual water resistance factor changes as a consequence. The salutation predicts velocity and pressure fields of the non-Newtonian incompressible fluid filtration for conditions of a non-deformable formation as well as a gel front trajectory in the fracture.The mathematical model of agent injection into the main fracture is based on the fundamental laws of continuum mechanics conservation describing the flow of non-Newtonian and Newtonian fluids separated by an interface plane in a flat channel with permeable walls. The mathematical model is based on a one-dimensional isothermal approximation, with dynamic parameters pressure and velocity, averaged over the fracture section.

Electrolysis-induced bubbling in soft solids for elastic-wave generation

Water electrolysis was discovered in 1800, with the famous experiment investigated here within soft tissue from an elastic-wave point of view. Indeed, we report that the rapid formation of hydrogen bubbles after transient (10 ms) electrolysis in water-based gels produces elastic waves. These bubbles are observed using an ultrafast optical camera. As the bubbles are trapped between the rigid electrode and the soft matter, they act as a source of elastic waves that are measured in the bulk using an ultrafast ultrasound scanner. The elastic-wave amplitude is shown to be in good agreement with a simple bubble model.

Re-doped fullerene-like MoS2 nanoparticles in relationship with soft lubrication

Inorganic, fullerene-like (IF) nanoparticles of tungsten disulfide (WS2) and molybdenum disulfide (MoS2) have been synthesised in the past and their useful tribological properties have been studied quite extensively. Rhenium doping of such nanoparticles was also reported and studied to some extent. Herein, further studies of the physico-chemical properties are reported in connection to lubrication under mild loads. Due to their self-repelling character, the doped nanoparticles form tessellated monolayers on certain substrates. When mixed in small amounts, the IF nanoparticles lead to a reduction in the viscosity of water-based gels. Furthermore, the added nanoparticles lead to a precipitous reduction in traction force (friction) under mild loads. The lubrication mechanism of such nanoparticles is briefly discussed.

Phase behaviour and thermodynamic properties of lamellar liquid crystal developed for viscoelastic surfactant based fracturing fluid

Phase behaviour of SDS/iso-amyl alcohol/pine oil/water and SDS/tert-amyl alcohol/pine oil/water systems were investigated for the development of viscoelastic surfactant (VES) based fracturing fluids having lamellar structures. The effects of co-surfactant, alkali, salt and nano-particle on rheology and thermodynamics of the lamellar liquid crystals were investigated. In contrast to tert-amyl alcohol, the use of iso-amyl alcohol as co-surfactant facilitated the formation of water-based gels. However, with subsequent addition of alkali, salt and nano-particles, VES fluid indicated an improvement in viscoelastic properties. Decrease in viscosity was observed with increase in temperature and shear rate. The developed VES fluids were miscible in water and nano-particle induced VES fluid exhibited satisfactory proppant suspension capability.

Effects of conducting media and gender on an electric pulp test

(1) To determine the pulpal sensory thresholds in human teeth obtained from using various EPT conducting media and (2) to determine whether there are gender differences. One intact maxillary central incisor was randomly selected from each of 40 participants (20 male, 20 female) aged 19-24 year. A constant-current electrical stimulator (University of Bristol, UK) was used to apply electrical stimuli with different conducting media at intervals of 1 min on the middle of the crown to evaluate the sensory threshold of the tooth. The tip of the electrode was coated with a thin layer of test media. The sensory thresholds and the pain scores were measured simultaneously after applying stimuli twice a second and gradually increasing the intensity until felt by the participants. Test media included water-based gels (K-Y UltraGel; Xylocaine 2% Jelly, electrode gel, fluoride gel) and toothpastes (Colgate Total; Sensodyne Repair & Protect; Dentiste' Plus White; Sparkle White). The sensory threshold data were evaluated using two-way anova followed by the Tukey test. Xylocaine 2% Jelly and fluoride gel evoked significantly lower threshold values when compared with Sensodyne Repair & Protect (P < 0.001). With all test media, the mean sensory threshold from the female group was significantly lower than that of the male group (P < 0.001). The sensory thresholds to electrical stimuli in human teeth was influenced by the type of conducting media and gender.

Thermal behavior of Li–Co-citric acid water-based gels as precursors for LiCoO2 powders

In the present work the thermal behavior of Li–Co-CA (citric acid) gels obtained by sol–gel method in aqueous media was studied. As reagents lithium and cobalt nitrates or acetates were used. The ultra-violet visible spectroscopic investigations indicate the formation of complex coordination gels in which Co(II) ion has an octahedral geometry. The Fourier-Transform Infrared spectroscopy suggests that the carboxyl groups provided by the citric acid act as bridging ligands for both studied gels. The obtained gels were analyzed by thermogravimetric and differential thermal analysis coupled with evolved gases analysis. A stepwise thermal decomposition of both types of gels was noticed with the evolution of different type of gases. These binary gels were comparatively investigated with the corresponding mono-metal-citric acid gels. The decomposition of both binary studied gels takes place up to 400 °C. Based on the thermal behavior of the complex gels, their annealing process was established. The binary gels thermally treated at 700 °C lead to single phase of lithium cobalt oxide (LiCoO2) powders.

Oral Hygiene In Dying Patients With Diminished Consciousness

Xerostomia (subjective sensation of oral dryness) and stomatitis (sore mouth) are common in patients with terminal disease and have considerable impact on patients' wellbeing. Patients with diminished consciousness may still be aware of oral discomfort such as a dry mouth. Therefore, good oral hygiene is an important nursing role when caring for terminally ill and dying patients. However, in terminally ill and dying patients who are semi-conscious or unconscious, oral care is often based on historical anecdote rather than robust research evidence and nurses often lack knowledge about the most effective care practices. This article will make recommendations for clinical practice to support nurses or healthcare assistants when carrying out oral care on patients who are at the end of life and are semi-conscious or unconscious. It will consider the evidence for the effectiveness, appropriateness and patient acceptability of oral-cleansing substances, toothbrushes and foam swabs, petroleum jelly and water-based gels for dry lips, topical saliva stimulants and saliva substitutes, as well as topical treatments for stomatitis. Conflicts of interest: none