Rheological Measurements Research Articles

Dynamic and thermodynamic behavior of supercooled Na–Ba metaphosphate liquids: Role of modifier cation ordering

AbstractThe Q‐speciation and the role of modifier dynamics on network relaxation in the supercooled mixed‐alkali–alkaline‐earth (MAAE) Na–Ba metaphosphate liquids are investigated using a combination of 31P nuclear magnetic resonance (NMR) spectroscopy, calorimetric, electrical conductivity, and rheological measurements. Progressive replacement of Na with Ba in these glasses is shown to result in an increasing disproportionation of Q2 species via the reaction: 2Q2 = Q1 + Q3. Unlike mixed‐alkali liquids, the Na–Ba metaphosphate liquids display a monotonic variation in isothermal electrical conductivity, glass transition temperature, calorimetric and kinetic fragility, and isothermal viscosity. It is hypothesized that this monotonic variation arises from the lack of elastic facilitation of network relaxation via coupled hopping of Na–Ba pairs as these modifier cations are prohibited from mixing randomly due to the differences between their size, mass, charge, and mobility. Isobaric heat capacity measurements provide supporting evidence in favor of a such a nonrandom mixing between the modifier cations in Na–Ba metaphosphate glasses and liquids.

Rheological, Thermal, and Textural Characteristics of White, Milk, Dark, and Ruby Chocolate

This study compares the rheological, thermal, and textural characteristics of four types of chocolate—white, milk, ruby, and dark—produced by the same manufacturer. White, milk, and ruby chocolates contain 36% fat, while dark chocolate has 39%. Cocoa content varies from 28% in white, 33% in milk, 47% in ruby, to 70% in dark chocolate. Rheological properties were assessed with a rotational rheometer, while density was measured with a gas pycnometer. Particle size distribution (PSD) was evaluated using laser diffraction, and thermal properties were analyzed with differential scanning calorimetry (DSC). The DSC results indicated that enthalpy increased with cocoa content, whereby dark chocolate showed the highest value (55.04 J g−1) and white chocolate the lowest (35.3 J g−1). PSD followed a monomodal pattern; dark chocolate had the smallest particles, leading to the highest hardness. Density ranged from 1.2773 to 1.2067 g∙cm−3. The results from classical rotational rheological measurements were in accordance with oscillatory measurements. Rheological measurements confirmed that the Casson yield stress was the highest for milk chocolate (17.61 Pa). The viscosity values decreased with increasing shear rate for all chocolates. All chocolate samples showed strong shear-thinning behavior up to a 100 s−1 shear rate. Oscillatory measurements showed the paste-like nature of all samples, i.e., storage modulus G’ dominates loss modulus G’’ at small shear stress values, and the complex modulus G*, which represents the stiffness, varied as follows: milk > white > dark > ruby. This study offers valuable insights into the properties of chocolates during production and storage, helping manufacturers anticipate key characteristics for new confectionery products.

Hydroxyurea for Children and Adults with Hemoglobin SC Disease.

Hemoglobin SC (HbSC) is a common sickle hemoglobinopathy that causes acute complications, chronic organ damage, and early death with no established disease-modifying treatment. In this trial, we examined the safety and efficacy of hydroxyurea treatment in patients with HbSC. Prospective Identification of Variables as Outcomes for Treatment (PIVOT) was a double-blind, randomized, placebo-controlled, non-inferiority phase 2 trial in which we assigned children and adults with HbSC in Ghana to 12 months of hydroxyurea or placebo. The primary end point was hematologic dose-limiting toxicities (DLTs), including cytopenias or elevated hemoglobin levels during 12 months of blinded treatment. Clinical end points included vaso-occlusive pain events, acute chest syndrome, hospitalizations, transfusions, and malaria. Quality-of-life measures, organ function assessments, and rheological measurements were also collected. Of the 243 enrolled patients (118 female), 212 eligible participants initiated blinded treatment at 20.0±5.0 mg/kg/day. DLTs occurred in more participants on hydroxyurea (33%) than the placebo (11%), with a difference of 22 percentage points (95% confidence interval [CI],11 to 34 percentage points), which exceeded the predefined 15 percentage point noninferiority margin. Elevated levels of hemoglobin occurred in 12 participants on hydroxyurea and 10 on the placebo. Hydroxyurea treatment was associated with 57.0 versus 149.6 vaso-occlusive pain events per 100 person-years (incidence rate ratio [IRR] 0.38; 95% CI, 0.28 to 0.52), and 12.9 versus 30.6 hospitalizations per 100 person-years (IRR 0.42; 95% CI, 0.22 to 0.81). A composite of acute sickle-related events occurred in 37 participants on hydroxyurea versus 69 participants on placebo (IRR 0.39; (95% CI, 0.26 to 0.59), a difference observed in both children and adults. The PIVOT trial did not meet its primary end point. Hydroxyurea at 20 mg/kg in patients with HbSC was associated with more hematologic DLTs than placebo, but most were mild and transient. Hydroxyurea was associated with less vaso-occlusive pain and fewer sickle-related events in both children and adults; a new trial will need to be done to establish the efficacy of this approach. (Funded by Theravia; Pan-African Clinical Trials Registry number, PACTR 202108893981080).

Eutectogel-Based Drug Delivery: An Innovative Approach for Atenolol Administration

Background: Hypertension affects 32% of adults worldwide, leading to a significant global consumption of cardiovascular medications. Atenolol, a β-adrenergic receptor blocker, is widely prescribed for cardiovascular diseases such as hypertension, angina pectoris, and myocardial infarction. According to the Biopharmaceutics Classification System (BCS), atenolol belongs to Class III, characterized by high solubility but low permeability. Currently, atenolol is commercially available in oral formulations. Increasing attention is being directed towards developing cost-effective transdermal delivery systems, due to their ease of use and better patient compliance. Eutectogels represent next-generation systems that are attracting great interest in the scientific community. Typically obtained from deep eutectic solvents (DESs) combined with gelling agents, these systems exhibit unique properties due to the intrinsic characteristics of DESs. Methods: In this study, a DES based on choline chloride as a hydrogen bond acceptor (HBA) and propylene glycol as a hydrogen bond donor (HBD) was explored to enhance the topical delivery of atenolol. The solubility of atenolol in the DES was evaluated using spectroscopic and thermodynamic measurements which confirmed the formation of hydrogen bonds between the drug and DES components. Additionally, the safety of the DES was assessed in a cell viability assay. Subsequently, we formulated eutectogels with different concentrations using animal gelatin and Tego Carbomer 140, and characterized these formulations through rheological measurements, swelling percentage, and permeation studies with Franz cells. Results: These novel eutectogels exhibit superior performance over conventional hydrogels, with a release rate of approximately 86% and 51% for Carbomer- and gelatin-based eutectogels, respectively. In contrast, comparable hydrogels released only about 27% and 35%. Conclusions: These findings underscore the promising potential of eutectogels for the transdermal delivery of atenolol.

Effect of Froth on the Interaction Between Coal Particles and Cake Structures in the Dewatering Process of Clean Coal

Effective coal slurry water solid–liquid separation is indispensable for the recycling and sustainable development of coal resources. The interaction between bubble and coal particles plays a critical role in the process of dewatering for clean coal. In this study, we firstly conducted a comprehensive investigation of the impact of froth on the interactions between coal particles by rheological measurement and particle aggregation behavior. Furthermore, the macroscopic dewatering performance of coal slurry in the presence of froth and its microscopic cake structure were investigated using the filtration test and X-ray microtomography (CT). It was found that the interaction between coal particles in the presence of froth was enhanced as a result of the dynamic shear value, combined with the large floc size and compact structure, which led to a higher cake moisture and higher filtration velocity. The CT results indicated that the enhanced interaction of particles in the presence of froth also led to a dense microstructure of the filter cake. The porosity of the filter cake decreased to 2.05% when the aeration time increased from 0 s to 90 s, the throat radius in the filter cake was reduced to 1.32 μm, and the number of throat passages was reduced to one third. Multiple blind pores and low coordination numbers led to a poor connectivity of the pore network and high moisture content.

Complexation of magnesium ions in sodium dodecyl benzenesulfonate-Flopaam AN125SH mixtures using sodium citrate

Presence of divalent metal ions, especially alkaline earth cations in brine water is an important factor during different processes applying anionic surfactants and negatively charged polymers, because these cations bind to the anionic head group of surfactants and may cause the precipitation of these materials. They also interact with the polymer chains, decreasing the polymer’s viscosity, reducing the net charge of the polymer chains, which also may lead to precipitation. The present study focuses on describing the interactions between magnesium ions with anionic sodium dodecyl benzenesulfonate (SDBS)–Flopaam AN125SH mixtures and the complexation of the magnesium with sodium citrate. Description of these interactions are important to evaluate the applicability of sodium citrate to decrease the undesired effects of alkaline earth cations in polymer-surfactant mixtures. The mixtures contained the high molecular weight anionic polymer in constant 1.0 g/L concentration and the surfactant in 5.0 g/L concentration. The magnesium ion concentration was systematically increased in the samples (0.03–1.5 g/L) and sodium citrate was added to the magnesium ion containing samples in 2.0 and 3.0 M equivalent amount compared to the magnesium ion concentration. The samples were characterized by using turbidimetry and rheology measurements (measuring consistency index, yield stress, flow number and zero shear viscosity), as the change of viscosity is an important parameter during application of polymers in different processes. The formed precipitates were characterized using infrared spectroscopy. The results showed that sodium citrate successfully inhibited the magnesium ions caused precipitation up to 1.2 g/L metal ion concentration (1200 ppm), but caused a considerable decrease in the viscosity of the samples (the consistency index of the mixtures decreased from 47.5 mPa s to 7.53 mPa s) and that magnesium ions do not induce precipitation of the polymer. However, this amount of decrease in viscosity did not change the flow properties of the polymer, all the investigated samples were measured to possess pseudoplastic flow behavior. The viscosity decreasing effects of the sodium citrate were also measured and approximately 13.0 mPa s decrease was measured in zero shear viscosity.

Date palm (Phoenix dactylifera L.) pollen-based microgel and its promising medical and environmental applications

Pollen, a natural bi-layered porous microcapsule, plays a crucial role in plant reproduction by protecting the plant's genetic material. Due to its unique properties, it has garnered attention for medical and environmental applications. Recent studies have focused on transforming the pollen's rigid structure to soft, gel-like matter, enabling the creation of pollen-based products such as paper and sponge. The main factor in the gelation process involves pectin-to-pectate conversion within the pollen's inner layer. Previously, claimed that this transformation is restricted to eudicot plants, and some others, such as monocot plant pollens do not exhibit this gelation phenomenon. In this study, we successfully produced microgel from date palm (Phoenix dactylifera L.) pollen (DPP), challenging this assertion. A significant portion of these monocot plant pollens exceeds the requirement of date production, presenting an opportunity for large-scale production without environmental concerns. Here, we have prepared pollen-based microgel, paper, and sponge and conducted a comprehensive analysis using various techniques such as optical and fluorescence microscopy, scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), elemental CHN analysis, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric differential thermal analysis (TGA/DTA), rheological measurements, mechanical analysis, pH-sensitivity tests, swelling analysis, and oil absorption capacity. By discerning the specific physicochemical properties of these materials, we propose potential medical and environmental applications for further investigation.

Rheology of polyacrylamide-based fluids and its impact on proppant transport in hydraulic fractures

Rheological experiments and measurements of particle settling velocity under static conditions were conducted for two types of polyacrylamide (PAA-based) fluids. The flow behavior of the viscoelastic fluids is described by a simplified, three-parameter model that integrates a constant viscosity at low shear rates with a power-law viscosity dependency at higher shear rates. The estimated dependencies of the rheological parameters and particle settling velocity on PAA concentration align with the classical power-law scaling for semi-dilute polymer solutions. The identified scaling offers valuable insight for optimizing the chemical composition of fracturing fluids, thereby improving the efficiency of hydraulic fracturing technology. By applying the lubrication approximation to the Navier–Stokes equations, a set of equations for the suspension flow in a vertical plane channel, characterized by the three-parameter rheology model, was derived. In typical fracturing conditions, the conventional power-law viscosity model used in current fracturing simulators significantly overestimates the gap-averaged apparent fluid viscosity compared to the proposed model. The novel model of the suspension flow aims to enhance the accuracy of proppant transport models applied in hydraulic fracturing simulators. Based on the three-parameter rheology model, a new model of particle settling in the studied PAA-based fluids is developed. It is based on smart Stokes' law, where viscosity is calculated according to either the plateau or power-law region, depending on the self-induced shear rate. The new model more accurately approximates experimentally determined settling velocity of proppant under static conditions across a broad range of PAA concentrations than existing models.

Electrospinning of annatto-loaded cellulose acetate scaffolds using acetone/DMSO as solvent

Abstract Electrospinning has emerged as a versatile technique for producing nanofibers for diverse applications. The fibers produced are highly regarded for their biocompatibility, exceptional surface-to-volume ratios, porosity, and adjustable composition properties, making them promising scaffolds for tissue engineering. In the literature, annatto-loaded cellulose acetate has already been successfully used for electrospinning. However, N,N-dimethylformamide (DMF) was utilized as a solvent in the experiments, which is considered a carcinogenic and mutagenic substance. The aim of this study is to analyze whether comparable results can be achieved with a low toxicity solvent consisting of acetone and dimethyl sulfoxide (DMSO). In this study, we investigate the electrospinning process of cellulose acetate (CA) and cellulose acetate combined with annatto extract (CA/A). Initially, various polymer concentrations ranging from 12% to 16% (w/v) were characterized by rheological measurements to determine their suitability for electrospinning. The morphology and diameter distribution of the electrospun fibers were analyzed using scanning electron microscopy (SEM). Contact angle measurements were carried out to determine the wettability of the electrospun meshes. The rheological investigations conducted revealed that increasing the polymer content of CA raises viscosity, while the incorporation of annatto decreases it. Uniform fibers are achieved at polymer concentrations of 14% and above. The electrospun nanofibers exhibit uniform morphology and diameters in the nanometer range, indicating the successful fabrication of annatto-loaded CA nanofibers. The contact angle measurements showed hydrophilic behavior on all investigated meshes. The incorporation of annatto extract in the electrospun fibers holds promise for various applications, including biomedical scaffolds, scaffolds for cultured meat, filtration membranes and food packaging materials. This study provides valuable insights into optimizing electrospinning parameters for the fabrication of functional nanofibers with enhanced properties.

Synthesis of photo-responsive κ-carrageenan-based hydrogels for drug delivery application.

Natural polymer-based hydrogels may act as versatile platforms in controlled drug delivery. In this regard, photoactive κ-carrageenan (κ-Crg) hydrogels modified with cinnamate (CN) groups are developed for pH-sensitive release of drugs. κ-Crg-CN derivatives containing 17 %, 33 %, and 49 % cinnamate contents, named κ-Crg-CN1, κ-Crg-CN2, and κ-Crg-CN3, respectively, are prepared and cross-linked by UV-induced [2π + 2π] cycloaddition. Fourier transform infrared (FTIR) spectroscopy, Nuclear magnetic resonance (NMR), X-ray diffraction (XRD), and elemental analysis are conducted for structural characterization. Rheological measurements showed an increased degree of cross-linking density with the increase in cinnamate content, as represented by storage modulus (G') values of 226 Pa for κ-Crg-CN1, 631 Pa for κ-Crg-CN2, and 967 Pa for κ-Crg-CN3. Also, drug encapsulation efficiency using theophylline was significantly improved: 48 % for κ-Crg-CN1, 63 % for κ-Crg-CN2, and 85 % for κ-Crg-CN3. Theophylline release studies showed that at pH 1.2, it was slower than pH 7.2, with a release rate inversely proportional to the cinnamate content. Kinetic modeling showed a non-Fickian transport mechanism that involved diffusion and polymer relaxation. These results show that κ-Crg-CN hydrogels can act as tunable, pH-sensitive drug delivery systems, with mechanical properties and release profiles precisely tailored by cinnamate functionalization for applications in controlled drug delivery.

Enhancing CO2 Foam Stability with Hexane Vapours: Mitigating Coarsening and Drainage Rates

CO2 foams often suffer from poor stability due to high coarsening and coalescence rates, limiting their effectiveness in various applications. While it is well-established that small amounts of insoluble vapours such as alkane or fluorocarbon vapours can impede coarsening and recent studies have demonstrated their impact on coalescence, their specific effect on the CO2 foams has not been studied. This research provides a comprehensive examination of stabilising effect of hexane on CO2 foams in the presence of sodium dodecylbenzenesulfonate (SDBS). We investigated the foam stability of CO2 foams, benchmarking them against N2 foams by analysing foam lifetime, liquid drainage rate, and the evolution of bubble size. Additionally, we quantified the stabilising impact of hexane by calculating the coarsening rate. To gain insights into the adsorption mechanism of surfactants in the presence of hexane, we conducted surface tension and interfacial dilational rheology measurements, which demonstrated an increased adsorption of surfactant molecules at the interface and increased dilational viscoelasticity of interface when n-hexane was present. The introduction of hexane significantly improved foam stability, reducing coarsening rates by more than an order of magnitude. This improvement in foam stability is attributed to inhibited CO2 diffusion from the bubbles, as well as enhanced surfactant adsorption and surface elasticity, resulting in an approximate 3.6-fold increase in foam half-life.

Interactions Between Cationic Micellar Solution and Aromatic Hydrotropes with Subtle Structural Variations.

Wormlike micelles (WLMs) with tunable viscoelastic characteristics have emerged as indispensable smart materials with a wide range of applications, which have garnered intense interest over the past few decades. However, quantitatively predicting the effect of various hydrotropes on the rheological behaviors of WLMs remains a challenge. In this article, micelles were formed in a mixture of 3-hexadecyloxy-2-hydroxypropyltrimethylammonium bromide (R16HTAB) and aromatic hydrotropes (e.g., sodium benzoate, sodium cinnamate and their derivatives, respectively) in an aqueous solution. The phase behavior, viscoelasticity and thickening mechanism were systematically studied by macroscopic observation, rheological measurements, electrostatic potential analysis and cryogenic transmission electron microscopy (Cryo-TEM). Rheological measurements were used to probe the remarkable viscoelastic properties of micelles stemming from their lengthening and entanglement under the interaction between R16HTAB and hydrotropes with structural variations. For an equimolar system of R16HTAB and cosolute (40 mM), the relaxation time decreases in the following order: SpMB > SoHB > S4MS > SmMB > S5MS > SB > SmHB > SoMB > SpHB. These results allow us to predict the possible rules for the self-assembly of R16HTAB and aromatic hydrotropes, which is conductive to directionally designing and synthesizing smart wormlike micelles.

Preparation and characterization of sago/iota-carrageenan microgels as food thickener in texture modified food

An increasing number of older populations with swallowing difficulties need specialized diets with easy-to-chew and safe swallowing characteristics. Texture modification using a thickener is usually used to obtain the desired texture, which helps in lowering the risk of aspiration. Microgels usage to modify the texture and rheology of liquid and pureed foods has been an area of interest in the food industry for many years. Therefore, this study aimed to produce sago starch and ι-carrageenan based microgels with functionality as food thickeners. Different concentrations of ι-carrageenan (25%, 50% and 75%) were added into sago starch dispersion and then fabricated using ultrasound treatment followed by spray drying process. A commercial dysphagia thickener that is normally used at medical institutions and nursing homes was also included as a reference. Microgels with increasing ι-carrageenan concentration showed variation in behaviours during rheological and textural measurements. Rheological tests revealed that sago/ι-carrageenan microgels exhibited a predominant elastic behaviour, with G′>G″ within the frequency range. Texture profile analysis (TPA) suggested that the sample with 2.0 g of sago starch and 2.0 g ι-carrageenan, MS50, produced samples with similar hardness, springiness, and cohesiveness to the reference sample. Overall, sago/ι-carrageenan microgels have shown a potential to be used as an alternative thickener as it provides low adhesiveness and more elastic behaviour which is considered safe-to-swallow food, especially for elderly with swallowing difficulties.

Enhancing the quality attributes of porcine myofibrillar proteins through low-frequency alternating magnetic field-assisted freezing

This study explores the potential of low-frequency alternating magnetic field-assisted freezing (LF-MFF) on enhancing the physicochemical stability and gelling performance of porcine myofibrillar proteins (MPs). We observed that LF-MFF markedly reduced oxidative denaturation of MPs compared to refrigerator freezing (RF), thus maintaining higher gel quality. Notably, LF-MFF treatment at 3–4 mT enhanced MPs' solubility, decreased turbidity, and lowered dityrosine content. LF-MFF at 4 mT also effectively minimized MPs' aggregation and degradation. Rheological measurements revealed that the storage modulus (G') and apparent viscosity of MPs treated with 3–4 mT LF-MFF are comparable to those of fresh samples (FS). Furthermore, LF-MFF at 3–4 mT significantly improved the water-holding capacity (WHC), whiteness, gel strength, and textural properties of MPs. The 3–4 mT LF-MFF was particularly effective in enhancing hydrophobic interactions and hydrogen bonding, thereby inhibiting water mobility and protecting microstructure of MPs gels. In summary, LF-MFF, especially at 4 mT, improved the gelation properties of MPs by reducing oxidative denaturation, providing significant insights for its application in the frozen meat industry.

Unifying the roll waves.

Free surface flows down a slope occur in various real-life scenarios, such as civil engineering, industry, and natural hazards. Unstable waves can develop at the free surface when inertia is sufficiently strong, indicated by the Reynolds number exceeding a critical value. Although this instability has been investigated for specific fluids with different rheologies, a common framework is still lacking to facilitate comparison among the various models. In this study, we investigate the linear stability of a generalized Newtonian fluid, where the viscosity [Formula: see text] remains unspecified. We meticulously construct new dimensionless quantities to minimize dependence on the rheology, and subsequently derive the Orr-Sommerfeld equation of stability for any generalized Newtonian fluid, which has never been done before. We conduct a long-wave expansion and generate a novel analytical expression for the wave celerity, along with the critical Reynolds number. The originality in this study is that the analytical expressions obtained are valid for any rheology, and are easy to compute from a rheological measurement or from a base flow profile measurement. These results are subsequently scrutinized using various shear-thinning, shear-thickening, and viscoplastic rheology models. They exhibit excellent agreement with experimental or numerical data as well as theoretical findings from existing literature. Furthermore, the novel analytical expressions enable a much more comprehensive investigation into the impact of rheology on stability. While our approach does not encompass singular or non-monotonous rheology, the analytical expressions derived from the long-wave expansion exhibit remarkable resilience and they continue to accurately predict both the wave speed and the instability threshold in such cases.

Mobilization of poly- and perfluoroalkyl substances (PFAS) from heterogeneous soils: Desorption by ethanol/xanthan gum mixture

Remediating soils contaminated by per- and polyfluoroalkyl substances (PFAS) is a challenging task due to the unique properties of these compounds, such as variable solubility and resistance to degradation. In-situ soil flushing with solvents has been considered as a remediation technique for PFAS-contaminated soils. The use of non-Newtonian fluids, displaying variable viscosity depending on the applied shear rate, can offer certain advantages in improving the efficiency of the process, particularly in heterogeneous porous media. In this work, the efficacy of ethanol/xanthan mixture (XE) in the recovery of a mixture of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonate (PFHxS), and perfluorobutane sulfonate (PFBS) from soil has been tested at lab-scale. XE’s non-Newtonian behavior was examined through rheological measurements, confirming that ethanol did not affect xanthan gum’s (XG) shear-thinning behavior. The recovery of PFAS in batch-desorption exceeded 95 % in ethanol, and 99 % in XE, except for PFBS which reached 94 %. 1D-column experiments revealed overshoots in PFAS breakthrough curves during ethanol and XE injection, due to over-solubilization. XE, (XG 0.05 % w/w) could recover 99 % PFOA, 98 % PFBS, 97 % PFHxS, and 92 % PFOS. Numerical modeling successfully reproduces breakthrough curves for PFOA, PFHxS, and PFBS with the convection-dispersion-sorption equation and Langmuir sorption isotherm.

Predicting the Linear Low-Density Polyethylene Content of Custom Polypropylene Blends and Post-Consumer Materials Using Rheological Measurements.

Contributing to a sustainable economy requires the use of pure recycled materials. Analyzing polyolefin post-consumer materials and cross-contaminations in these materials is an essential part in ensuring consistent product quality. Therefore, the aim of this work was to quantify the linear low-density polyethylene (LLDPE) content in polypropylene (PP)-dominant strips. The materials investigated included virgin PP, custom PP-LLDPE blends and PP post-consumer recyclates. To this end, differential scanning calorimetry (DSC) and parallel-plate rheometry were used. For complementary measurements, Raman spectroscopy and atomic force microscopy (AFM) were employed, confirming the morphological occurrence of LLDPE enclosed in PP up to 30 wt%. The DSC measurements demonstrated that the evaluated specific melt and recrystallization enthalpies alone are insufficient to quantify the LLDPE content, especially at 1-10 wt%. The rheometric results showed a strong correlation between the cross-over point (COP) and zero-shear viscosity for pure PP grades, and there was a deviation from this correlation depending on the LLDPE content in the PP-LLDPE blends. An approach for determining low (1-15 wt%) and medium (up to 30 wt%) LLDPE quantities in PP via two mathematical models is proposed based on the rheometric measurements of custom blends and can be applied to assess the level of LLDPE contamination in PP post-consumer materials.

Exploitation of red beet peel powder as a natural food ingredient in whey-fruit based beverage

ABSTRACT Scientists and food producers are studying the potential of utilizing different by-products as highly nutritious food components to meet consumers’ growing demand for healthier and natural goods. Beetroot belongs to the Amaranthaceae family and is highly rich in antioxidants, specifically phenolics and betalains with excellent health properties. The peel of red beetroot, which is generally discarded, has a high concentration of bioactive phytochemicals (betalains, dietary fibers). These compounds are well-known for their strong antioxidant effects, improving cardiovascular health, reducing oxidative stress, and enhancing immunological function. Incorporating red beetroot peel (RBP) powder into whey-fruit-based beverages is a promising method to improve nutritional content and sensory attractiveness. This study investigated the influence of adding RBP to whey-fruit-based beverages, specifically examining its effects on physicochemical and phytochemical characteristics, antioxidant capacity, color, microbiological, and rheological attributes, and consumer preference. The RBP extract exhibited high amounts of total polyphenols (1239.35 ± 0.51 mg GAE/100 g dw) and antioxidant activity (90.02 ± 0.22%). The findings indicated that RBP had a notable impact on the antioxidant capacity (16.38 ± 0.37 μmol TE/g dw for BRBP1, 26.69 ± 0.10 μmol TE/g dw for BRBP3, 36.75 ± 0.31 μmol TE/g dw for BRBP6) of the beverages and enhanced their color without negatively impacting their sensory characteristics. The dynamic oscillatory rheological measurements revealed that beverage supplementation with increasing amounts of RBP obtained stronger networks with solid-like viscoelastic behavior. Using RBP powder as a natural food ingredient in whey-fruit-based beverages enhances their nutritional value and promotes sustainable food processing by making use of by-products from the food industry into innovative food options.

Formulation of Emulgels Containing Clotrimazole for the Treatment of Vaginal Candidiasis.

Vaginal candidiasis poses significant health concerns that affect approximately 75% of women globally and often leads to discomfort and a decrease in quality of life. Traditional treatments, despite their effectiveness, may cause discomfort and adverse effects, such as vaginal discharge, bleeding, and dryness, promoting the exploration of alternative formulations. In this study, we aimed to develop a novel therapeutic approach for the treatment of vaginal candidiasis utilizing oleic acid containing emulgels made from thermoresponsive poloxamer-based hydrogels. These emulgels were designed to provide a sustained release of clotrimazole, an antifungal agent. Incorporating oleic acid enhanced the drug's solubility and contributed to vaginal health. The formulations were characterized by their rheological properties, in vitro release, mucoadhesion, and spreadability. We conducted rheological measurements on the hydrogels that served as the base for the emulgels, as well as on the emulgels themselves. The emulgels exhibited continuous rheological behavior with changing temperatures, making them suitable for storage at room temperature. With an increasing HPMC content, we achieved enhanced mucoadhesion, which is beneficial for formulations used in body cavities. Moreover, in vitro release studies revealed sustained drug release profiles, which can be adjusted by varying the ratios of poloxamers and HPMC. These findings suggest that the developed emulgels offer a promising therapeutic option for vaginal candidiasis, addressing both the symptoms and the treatment of discomfort.

Gelation and Cryogelation of Chitosan: Origin of Low Efficiency of Diglycidyl Ethers as Cross-Linkers in Acetic Acid Solutions

Although diglycidyl ethers of glycols (DEs)—FDA-approved reagents for biomedical applications—were considered unsuitable for the fabrication of chitosan (CH) hydrogels and cryogels, we have recently shown that CH cross-linking with DEs is possible, but its efficiency depends on the nature of the acid used to dissolve chitosan and pH. To elucidate the origin of the low efficiency of chitosan interactions with DEs in acetic acid solutions, we have put forward two hypotheses: (i) DEs are consumed in a side reaction with acetic acid; (ii) DE chain length strongly affects the probability of cross-linking. We then verified them using FT-IR spectroscopy, rheological measurements, and uniaxial compression tests. The formation of esters in acetic acid solutions was confirmed for ethylene glycol diglycidyl ether (EGDE) and poly(ethylene glycol) diglycidyl ether (PEGDE). By the 7th day of gelation at pH 5.5, the G’HCl/G’HAc ratio was 5.1 and 1.5 for EGDE and PEGDE, respectively, indicating that the loss of cross-linking efficiency in acetic acid solution was less pronounced for the long-chain cross-linker. Under conditions of cryotropic gelation, only weak cryogels were obtained from acetic acid solutions at a DE:CH molar ratio of 1:1, while stable cryogels were fabricated at a molar ratio of 1:20 from HCl solutions.