Slow Dissolution Research Articles

Early age properties and water resistance of calcium hydroxide modified volcanic ash‐based phosphate geopolymer binders

AbstractThis work aims to improve the early age characteristics and water resistance of volcanic ash‐based phosphate geopolymer materials by modifying the chemistry of the binder with calcium hydroxide (CH). Phosphate geopolymer binders with Ca/P molar ratios ranging from 0.49 to 0.80 were prepared. Then the early and late age physical properties were then determined. The hardened binder was characterized by various analytical techniques involving XRD, TGA‐DSC, and SEM‐EDS. The results showed that the use of CH decreases the initial setting time from several hours to less than 5 min. At the same time, the 1 d compressive strength was increased from 0 to 15 MPa with the increase in the Ca/P molar ratio. Moreover, the slow dissolution rate of volcanic ash was responsible for the low strength at an early age but beneficial to improving the geopolymerisation with time. This favored the high strength of the control phosphate geopolymer, which reached 52.5 MPa at 56d and was higher than those with CH (28.5–45.2 MPa). However, the control phosphate geopolymer had poor water resistance, with strength retention ranging from 21%–57% compared to 76%–90% for phosphate geopolymer with CH. This is because of the leaching of the reactive phase underwater that inhibits further reaction progress. In addition, the modification of the binder chemistry with CH leads to the formation of new calcium phosphate phases that also contribute to enhancing water resistance.

Precipitation Mechanism of VOSO4 in Oversaturated Electrolytes of the Solid-Liquid Storage Method in Vanadium Redox Flow Batteries

Redox flow batteries (RFBs)-based storage systems have the unique feature of separate power generating and energy storage units that can be individually sized. RFBs can be used for days-long energy storage, but because of the low solubility of most ions and molecules in both aqueous and non-aqueous solvents,[1,2] scaling these RFB systems for days-long applications requires a lot of storage tanks and floor area. Our team has developed a new storage method that can significantly increase energy storage density while still maintaining the traditional flow battery design.[3] This method involves storing the reactants in both soluble ions and undissolved solid form, and only the liquid containing the soluble ions is circulated through the batteries. A larger than 4X improvement in storage energy density may be achieved with this strategy. The feasibility of this method was demonstrated in a hydrogen-vanadium (VI/V) RFB.[4] From the study, a major factor in achieving high performance with this hybrid storage system is the rates of the precipitation of the saturated electrolyte and dissolution of the solid precipitate. It was discovered that not all vanadium sulfate solids have precipitation rates fast enough to generate the active ions at the rate needed in the electrode reaction. Only the low crystallinity solid generated by rapid precipitation by the use of a suitable nucleation material was found to have the dissolution rate needed. This presentation will discuss the role of the molecule structures and the mechanism of the precipitation process in the formation of solids that have slow and fast dissolution rates.

L-proline as co-crystal forming amino acid for enhanced dissolution rate of lamotrigine: Development of buccal tablet

Lamotrigine is an antiepileptic drug with slow dissolution rate which can reduce its oral bioavailability. In addition, it was reported to have first pass metabolism. Accordingly, the aim of this work was to enhance its dissolution rate utilizing co-crystallization technique to be suitable for incorporation in buccal dosage form. L-proline was selected as co-crystal co-former for enhancing dissolution in addition to its beneficial anticonvulsant properties. Formulations containing lamotrigine and L-proline at different molar ratios were prepared using ethanol assisted co-grinding. The prepared formulations were characterized using FTIR, X-Ray powder diffraction, differential scanning calorimetry and dissolution studies. The formulation recorded the highest dissolution rate was incorporated in fast disintegrating tablet for buccal use. Characterization techniques suggested the formation of lamotrigine-l-proline co-crystals with 1:2 molar ratio being optimum for interaction. This interaction resulted in significant enhancement in dissolution rate with the ratio of lamotrigine to proline at molar ratio of 1:4 showed greatest dissolution rate (% DE= 80.57). The prepared tablet utilizing lamotrigine and L-proline at molar ratio of 1:4 showed fast disintegration and rapid dissolution rate compared with control tablet containing lamotrigine alone. The study suggested L-proline as an efficient co-crystal co-former for enhancing dissolution rate of lamotrigine for buccal delivery.

Modification of grain boundary microstructure by controlling dissolution behavior of θ particles in Cr-containing hypereutectoid steel

To overcome the brittleness of high‑carbon steels, it is necessary to develop the strategy to remove the carbides on the grain boundaries and strengthen grain boundaries. In this paper, we achieved them by simply controlling the heat treatment conditions and the microstructure before heat treatment. It was found the dissolution behavior of the θ-cementite particles is changed greatly with and without Cr in the high‑carbon steels. In the Cr-free hypereutectoid steel, dissolution of θ particles at high temperatures is remarkably fast, but the dissolution behavior is greatly affected by the microstructure in the Cr-containing hypereutectoid steel. In the Cr-containing hypereutectoid steel, the dissolution of θ particles into the γ-austenite phase was rapid in steel with smaller θ particles in fine α grains, but slow in steel with larger θ particles in coarse α grains. The θ particles on the grain boundaries preferentially dissolved and rapidly disappeared in the initial stage of the dissolution treatment owing to the contribution of grain boundary diffusion, since the grain boundary diffusion of Cr is fast as comparable to C. However, the θ particles inside the grains slowly dissolved and then remained until the later stage, owing to slow dissolution via the partition local equilibrium (PLE) mode controlled by the lattice diffusion of Cr. Owing to the preferential dissolution of θ particles on the grain boundaries in the initial stage, large amounts of Cr atoms dissociated from the θ particles diffused along the grain boundaries with grain boundary diffusion, forming Cr-enriched grain boundaries. Such grain boundary microstructure control is expected to lead to the suppression of intergranular fracture, resulting in the improvement of fracture toughness.

Playing it the nation’s way: tradition, cosmopolitanism, and the native-masculine of Hindi sports films

ABSTRACT The generic popularity of Hindi sports films has been overwhelming in recent years. The article examines this genre of Hindi films through the thematic construction of the sports‘man’ and its evolutionary manifestation from a masculine figure symbolising India’s national unitarian ethos to a megalithic, tradition-backed, orthodox patriarchy post-2010s. It elaborates this seemingly linear transformation through decade based phases, starting from the social-emancipatory athletic phenomenon of the pre-globalisation era to the neoliberal Hindi sports films of the early millennial phase. The study then explores the slow dissolution of the ‘composite masculinity’ that considered the ethnic variegation of Indian nationalism, and the emergence of sporting cinema on patriarchal and athletic superheroes. The article further discusses how it was nurtured within deeply insular, and ethno-religious gaming traditions of antiquity like the akhara wrestling, in fictional/biographical sports films like Sultan (Zafar 2016) and Dangal (Tiwari 2016). While commenting on this transformation of the ‘national athlete’ into the ‘heritage’s surrogate’, the article attempts to provide a detailed methodology of understanding the expanding canon of Hindi sports films so far and how it aligns itself with the re-ethnicisation of India’s polity in the last two decades.

Lanthanum Silicate Nanomaterials Enhance Sheath Blight Resistance in Rice: Mechanisms of Action and Soil Health Evaluation.

In the current study, foliar spray with lanthanum (La) based nanomaterials (La10Si6O27 nanorods, La10Si6O27 nanoparticle, La(OH)3 nanorods, and La2O3 nanoparticle) suppressed the occurrence of sheath blight (Rhizoctonia solani) in rice. The beneficial effects were morphology-, composition-, and concentration-dependent. Foliar application of La10Si6O27 nanorods (100 mg/L) yielded the greatest disease suppression, significantly decreasing the disease severity by 62.4% compared with infected controls; this level of control was 2.7-fold greater than the commercially available pesticide (Thifluzamide). The order of efficacy was as follows: La10Si6O27 nanorods > La10Si6O27 nanoparticle > La(OH)3 nanorods > La2O3 nanoparticle. Mechanistically, (1) La10Si6O27 nanorods had greater bioavailability, slower dissolution, and simultaneous Si nutrient benefits; (2) transcriptomic and metabolomic analyses revealed that La10Si6O27 nanorods simultaneously strengthened rice systemic acquired resistance, physical barrier formation, and antioxidative systems. Additionally, La10Si6O27 nanorods improved rice yield by 35.4% and promoted the nutritional quality of the seeds as compared with the Thifluzamide treatment. A two-year La10Si6O27 nanorod exposure had no effect on soil health based on the evaluated chemical, physical, and biological soil properties. These findings demonstrate that La based nanomaterials can serve as an effective and sustainable strategy to safeguard crops and highlight the importance of nanomaterial composition and morphology in terms of optimizing benefit.

Soil habitat function after innovative nanoagriproducts application: Effect of ageing on the avoidance behaviour of the soil invertebrates Enchytraeus crypticus and Folsomia candida

Research on nanotechnology with applications in agriculture has been gathering attention because it may achieve a good balance between agricultural production and environmental integrity. Among the vast nanomaterials, layered double hydroxides (LDHs) are a promising solution for supplying crops with macro- and/or micronutrients. Still, little is known about their safety implications for non-target organisms, such as soil invertebrates. The habitat function of soils might be impacted by potential stressors, which can be assessed through avoidance behaviour tests. This study aimed to assess the effect of two innovative agriproducts, Zn-Al-NO3 LDH and Mg-Al-NO3 LDH, on the avoidance behaviour of the enchytraeid Enchytraeus crypticus and the collembolan Folsomia candida, over time. Simultaneously, Zn and Mg potential release from LDHs to soil was evaluated. Overall, the behaviour of soil invertebrates differed between species, with enchytraeids being more sensitive to LDHs-treated soils than collembolans, possibly explained by their different physiological traits. The behaviour of soil organisms also depended on the LDH structural composition and was time-variable. Soil treated with Zn-Al-NO3 LDH was perceived as less favourable compared to Mg-Al-NO3 LDH, which was preferred to clean soil at most tested concentrations. LDHs toxicity was partly, but not exclusively, related to Zn and Mg release. Cations release over time was demonstrated in the chemical assessment. Still, LDHs toxicity to soil invertebrates decreased as increasing AC50 values were derived over time. Slower dissolution over time might explain the decrease in toxicity. Our study demonstrates that both soil invertebrates could sense LDHs in soil and eventually adapt their behaviour by avoiding or preferring, according to the type and level of LDH present.

Effect of Drug-Polymer Interaction in Amorphous Solid Dispersion on the Physical Stability and Dissolution of Drugs: The Case of Alpha-Mangostin.

Improving drug solubility is necessary for formulations of poorly water-soluble drugs, especially for oral administration. Amorphous solid dispersions (ASDs) are widely used in the pharmaceutical industry to improve the physical stability and solubility of drugs. Therefore, this study aims to characterize interaction between a drug and polymer in ASD, as well as evaluate the impact on the physical stability and dissolution of alpha-mangostin (AM). AM was used as a model of a poorly water-soluble drug, while polyvinylpyrrolidone (PVP) and eudragit were used as polymers. The amorphization of AM-eudragit and AM-PVP was confirmed as having a halo pattern with powder X-ray diffraction measurements and the absence of an AM melting peak in the differential scanning calorimetry (DSC) curve. The solubility of amorphous AM increased in the presence of either eudragit or PVP due to amorphization and interactions of AM-polymer. Furthermore, FT-IR spectroscopy and in silico studies revealed hydrogen bond interactions between the carbonyl group of AM and the proton of eudragit as well as PVP. AM-eudragit with a ratio of 1:1 recrystallized after 7 days of storage at 25 °C and 90% RH, while the AM-PVP 1:4 and 1:10 samples retained the X-ray halo patterns, even under humid conditions. In a dissolution test, the presence of polymer in ASD significantly improved the dissolution profile due to the intermolecular interaction of AM-polymer. AM-eudragit 1:4 maintained AM supersaturation for a longer time compared to the 1:1 sample. However, a high supersaturation was not achieved in AM-PVP 1:10 due to the formation of large agglomerations, leading to a slow dissolution rate. Based on the results, interaction of AM-polymer in ASD can significantly improve the pharmaceutical properties of AM including the physical stability and dissolution.

ALS Variants of Annexin A11's Proline-Rich Domain Impair Its S100A6-Mediated Fibril Dissolution.

Mutations in the proline-rich domain (PRD) of annexin A11 are linked to amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease, and generate abundant neuronal A11 inclusions by an unknown mechanism. Here, we demonstrate that recombinant A11-PRD and its ALS-associated variants form liquidlike condensates that transform into β-sheet-rich amyloid fibrils. Surprisingly, these fibrils dissolved in the presence of S100A6, an A11 binding partner overexpressed in ALS. The ALS variants of A11-PRD showed longer fibrillization half-times and slower dissolution, even though their binding affinities for S100A6 were not significantly affected. These findings indicate a slower fibril-to-monomer exchange for these ALS variants, resulting in a decreased level of S100A6-mediated fibril dissolution. These ALS-A11 variants are thus more likely to remain aggregated despite their slower fibrillization.

Eutectic Mixtures to Enhance the Solubility of Active Pharmaceutical Ingredients: Density Functional Theory and Infrared Spectroscopy Approaches

AbstractThe major issue with active pharmaceutical ingredients (APIs) is their slow dissolution rate and solubility. This makes them less likely to get into the body and less bioavailable. About 40 % of the drugs already on the market and 90 % being made have APIs that do not dissolve well in water. To deal with this problem, authors have designed eutectic mixture (EMs) of different drugs (danazol, griseofulvin, mefenamic acid, tolfenamic acid and tadalafil) with zinc chloride; studied their interaction and thermodynamic parameters using Density Functional Theory (DFT) computation. DFT calculations confirm an increase in the dipole moment of their EMs in comparison of APIs alone which increases the solubility. The change in Gibbs free energy of formation of EMs in the gaseous phase shows their feasibility ans stability.

Complete power cycle exhaust heat regeneration and the second law of thermodynamics

A closed condensing power cycle using tetrafluoromethane or R14 and a solid solute as its working fluid is described. The inclusion of a solid solute that yields a positive excess enthalpy of solution with the R14 creates a potential for complete exhaust heat regeneration. The solution reaction provides a temporary thermal reservoir for the cycle's low temperature exhaust heat until that energy is regenerated as heat by retrograde solubility during the cycle's high temperature and low density expansion phase. A slow solute dissolution rate in the solvent's low density state near the cycle's high temperature enables the cycle to utilize all of the regenerated exhaust heat either as work output or by exhausting surplus heat at a second temperature level. The cycle's thermodynamic path establishes solvent property reference points that can be used to determine the maximum positive excess enthalpies of solution required for a solvent to accomplish total exhaust heat regeneration when used as the cycle's working fluid.

Intranasal Microemulsion as an Innovative and Promising Alternative to the Oral Route in Improving Stiripentol Brain Targeting.

Stiripentol (STP) is a new-generation antiepileptic only available for oral administration. However, it is extremely unstable in acidic environments and undergoes gastrointestinal slow and incomplete dissolution. Thus, STP intranasal (IN) administration might overcome the high oral doses required to achieve therapeutic concentrations. An IN microemulsion and two variations were herein developed: the first contained a simpler external phase (FS6); the second one 0.25% of chitosan (FS6 + 0.25%CH); and the last 0.25% chitosan plus 1% albumin (FS6 + 0.25%CH + 1%BSA). STP pharmacokinetic profiles in mice were compared after IN (12.5 mg/kg), intravenous (12.5 mg/kg), and oral (100 mg/kg) administrations. All microemulsions homogeneously formed droplets with mean sizes ≤16 nm and pH between 5.5 and 6.2. Compared with oral route, IN FS6 resulted in a 37.4-fold and 110.6-fold increase of STP plasmatic and brain maximum concentrations, respectively. Eight hours after FS6 + 0.25%CH + 1%BSA administration, a second STP brain concentration peak was observed with STP targeting efficiency being 116.9% and direct-transport percentage 14.5%, suggesting that albumin may potentiate a direct STP brain transport. The relative systemic bioavailability was 947% (FS6), 893% (FS6 + 0.25%CH), and 1054% (FS6 + 0.25%CH + 1%BSA). Overall, STP IN administration using the developed microemulsions and significantly lower doses than those orally administrated might be a promising alternative to be clinically tested.

Exploiting common ion addition to accelerate zolpidem hemitartrate release from Eudragit EPO extrudates

The current study aimed at optimizing a previously developed non-clinical formulation for use in zolpidem deprescribing. The formulation under investigation consists of extruded zolpidem hemitartrate (30% w/w) and Eudragit EPO (70% w/w) mixtures which display unsatisfactory dissolution behavior. Both milled extrudates and physical mixtures were compressed to produce tablets with identical target weight and solid fraction. First, the susceptibility of zolpidem hemitartrate towards heat and shear degradation was identified utilizing thermal and HPLC-DAD analysis. The drug salt proved prone to thermally induced disproportionation. Moreover, the impurity content increased after applying hot melt extrusion although ICH guidelines were still attained. Secondly, extrudates and physical mixtures were subjected to FTIR analysis. As a result, interaction and protonation of the dimethyl aminoethyl group from Eudragit EPO resulting from zolpidem disproportionation was elucidated. As such, the formulations’ slow dissolution kinetics in comparison to formulations containing non-ionizable polymers (e.g. Kollidon 12PF and Kollidon VA64) is explained. Finally, addition of tartaric acid, a microenvironmental pH modulator and common ion, proved a successful method to increase dissolution kinetics. The amount of drug released after 15 min increased drastically from 10 to 40% upon the addition of 5% tartaric acid. Immediate release behavior (80% within 15 min) was however not yet attained.

Dual-confinement effect in metal oxide nanoparticles/MXene-reduced graphene oxide for high capacitive deionization performance

Metal oxide nanoparticles are one kind of important electrode materials for capacitive deionization (CDI) application. Unfortunately, most metal oxide materials usually exhibit poor electrical conductivity and often experience slow dissolution of metallic species, thereby resulting in limited desalination performance. Overcoming these obstacles still remains challenging due to the lack of synthetic approaches. Taking it into consideration, herein we proposed a dual confinement strategy to promote the CDI application of metal oxide nanoparticles. Nb2O5 was synthesized as a typical example for designing metal oxide/MXene-reduced graphene oxide (rGO) derived from Nb2CTx MXene/graphene oxide (GO) under hydrothermal condition. In the hybrid, Nb2CTx and rGO serve as both the confinement agent and conductive support for Nb2O5 nanoparticles, endowing Nb2O5/Nb2CTx-rGO with improved electronic conductivity and structural stability. As a result, the hybrid shows an outstanding desalination performance, including a NaCl adsorption capacity of 41.07 mg g−1, an ultra-fast average NaCl adsorption rate of 4.14 mg g−1 min−1 and excellent long-term cycling stability of 50 cycles (81 % desalination capacity retention rate). This work is expected to bring new insights in the synthesis of metal oxide materials for electrochemical desalination.

Adjusting the valence band center of Co-Ni-bimetallic sulfides through lattice expansion and stacking faults triggered by strain engineering to boost oxygen evolution reaction

Stress engineering can improve catalytic performance by straining the catalyst lattice. An electrocatalyst, Co3S4/Ni3S2-10%Mo@NC, was prepared with abundant lattice distortion to boost oxygen evolution reaction (OER). With the assistance of the intramolecular steric hindrance effect of metal–organic frameworks, slow dissolution by MoO42- of the Ni substrate and recrystallization of Ni2+ was observed in the process of Co(OH)F crystal growth with mild temperature and short time reaction. The lattice expansion and stacking faults created defects inside the Co3S4 crystal, improved the material conductivity, optimized the valence band electron distribution of the material, and promoted the rapid conversion of the reaction intermediates. The presence of reactive intermediates of the OER under catalytic conditions was investigated using operando Raman spectroscopy. The electrocatalysts exhibited super high performance, a current density of 10 mA cm−2 at an overpotential of 164 mV and 100 mA cm−2 at 223 mV, which were comparable to those of integrated RuO2. Our work for the first time demonstrates that the dissolution–recrystallization triggered by strain engineering is a good modulation approach to adjust the structure and surface activity of catalyst, suggesting promising industrial application.

Two Polymorphic Cocrystals of Theophylline with Ferulic Acid

In this study, the crystal structures of 1:1 theophylline–ferulic acid cocrystal polymorphs are reported for the first time. Interestingly, both forms crystallize in the same space group but with a different number of molecules in the asymmetric unit (form I = 2; form II = 4). The two polymorphs show distinct crystal morphology, demonstrating prism and rod single crystals, respectively. Theoretical calculations are performed to predict their morphology and thermodynamic stability (form I > form II). The prediction result agrees well with the measured pharmaceutical properties. Form I presents better hygroscopic stability (RH < 95%), slower dissolution, and lower solubility (1.06 ± 0.03, 1.63 ± 0.01, 1.30 ± 0.08 and 4.09 ± 0.05 mg/mL in water, pH = 1.2, pH = 4.5 and pH = 6.8 buffered solutions) over form II (8.45 ± 0.33, 2.41 ± 0.17, 3.46 ± 0.26 and 28.71 ± 0.87 mg/mL in water, pH = 1.2, pH = 4.5 and pH = 6.8 buffered solutions). In summary, this work elucidates the experimental findings with relevant predictions systematically and enriches our understanding of the structure–property relationship of the theophylline cocrystal system.

Tuning formation process of void defects in microcolumn arrays via pulse reverse electrodeposition

The pulse reverse current electrodeposition process consists of two stages: the forward deposition and reverse dissolution. This study aims to understand the characteristics of forward deposition and reverse dissolution and to reveal their influences on the formation of void defects in electrodeposited microcolumn arrays. Both the simulation and experimental results show that pulse reverse current contributes to the void-free deposition of microcolumn arrays. During the deposition under forward pulse stage, the thickness of deposited layer in micro cavities via pulse reverse current is more uniform compared with direct current. Meanwhile, the dissolution behavior under reverse pulse stage is greatly determined by the reverse pulse current density. A low reverse pulse current density (1 A/dm2) leads to a slow dissolution at the mouth of micro cavities. In contrast, a high reverse pulse current density (4 A/dm2) contributes to a high electrolyte potential, as well as a rapid dissolution at the mouth of micro cavities, which helps to eliminate void defects. The experimental results exhibit that void-free microcolumn arrays with a high aspect ratio of 5:1 are obtained via pulse reverse current. This study provides a clear understanding on the formation process of void defects in microcolumn arrays via pulse reverse electrodeposition.

Nanoencapsulated cordyceps extract enhances collagen synthesis and skin cell regeneration through antioxidation and autophagy

Oxidative stress from reactive oxygen species is the main cause of skin ageing. Cordycepin, a bioactive compound of Cordyceps militaris, contains antioxidant activity. This study examined extracellular matrix, antioxidant effect, autophagy activity, and skin regeneration in human dermal fibroblasts (HDFs) under normal and oxidative stress conditions. Slow disintegration was used to create nano-encapsulated cordyceps extract. HDFs were cultured and treated with 1 M cordycepin, 1 M medium, 0.1 M cordyceps medium loaded nanoparticles (CMP), or 1 mM H2O2. HDFs’ senescent phenotypes were assessed, including cell proliferation, ROS scavenging, collagen and elastin synthesis, antioxidant activity, and wound healing. CMP size averaged 184.5 ± 95.2 nm increased cell proliferation and reduced H2O2-induced ROS. Thus, HDFs treated for 48 h increased skin regeneration activity 2.76-fold by expressing extracellular matrix and rescuing H2O2-induced damaged cells. It was significant that this CMP inhibited H2O2-induced oxidative stress and induced autophagy to regenerate HDFs. The developed CMP could be used in cosmetics.

Hydration kinetics of clinoptilolite zeolite blended ternary cementitious materials with fly ash and metakaolin

The typical characteristics of hydration kinetics for the natural zeolite blended cementitious system may be impacted due to the varied sources and compositions of the zeolite particles. Previous research reported that the substitution of portland cement with natural clinoptilolite zeolite substantially minimized the tricalcium aluminate (C3A) peak heat of hydration apart from the regular matrix of the hydration kinetics, an indication of the potential interaction of zeolite particles in the blended system. Therefore, the present study investigated the suitable reasons for minimizing C3A peak heat of hydration in the blended system replacing the portland cement with clinoptilolite zeolite up to 20% by mass. Similarly, class C fly ash and metakaolin were utilized up to 20% by mass to observe the hydration kinetics of the zeolite blended ternary cementitious system. Additional 5% gypsum replaced the portland cement in the zeolite mixed system to verify the undersulfation. The heat of hydration was observed via isothermal conduction calorimetry. Phase identification of hydration products was done by x-ray diffraction (XRD) analysis at an early age of 3 days. Results revealed that the minimized C3A peak heat of hydration was not due to the undersulfation. Results also revealed that the zeolite blended ternary samples (i.e., cement-zeolite-class C fly ash, and cement-zeolite-metakaolin) obtained a relatively higher C3A peak heat flow and an increased duration for the monosulfate formation compared to the binary (i.e., cement-zeolite) samples. Likely, zeolite particles had a relatively slow chemical dissolution compared to the class C fly ash and metakaolin particles which supplied comparatively reduced amounts of alumina in the system in the early ages. The XRD results indicate the potential formation of a new hydration product (calcium-aluminum–silicate-hydrate), which likely consumed a reasonable amount of aluminate leading to a minimized C3A peak heat of hydration in the clinoptilolite zeolite blended system.

Development and technological research of medicated lozenges for catarrhal and aphthous stomatits` symptoms relief

inflammatory diseases of the oral cavity, in particular catarrhal and aphthous stomatitis, create significant discomfort for patients in everyday life. The occurrence of stomatitis in adolescents can be associated with numerous factors: bacterial and viral infection, insufficient oral hygiene, trauma of the mucous membrane, unbalanced nutrition, allergic reactions, some types of systemic diseases etc. Medicated lozenges have advantages for use in adolescents, as they have an interesting appearance (resembling a candy), pleasant taste and aroma, do not require swallowing or washing down with water, release active pharmaceutical ingredients by gradual dissolution in the oral cavity, which ensures their local action. The present work is aimed to develop different formulations of medicated lozenges for catarrhal and aphthous stomatits` symptoms relief. The objects of the study were experimental samples of lozenges with licorice root and propolis extracts. They were chosen as active ingredients due to their antimicrobial properties, as well as their ability to improve the general condition of the periodontium and reduce the outbreak of aphthae in stomatitis. Lozenges were prepared by heating and congealing method using different concentrations of active pharmaceutical ingredients and excipients (candy base substances – sugar substitute (isomalt), glucose syrup, carboxymethyl cellulose). 3 best formulations that had a uniform color distribution and were transparent, not sticky, had no external surface defects were subjects of the development and analysis. Obtained medicated lozenges were evaluated for physical parameters like weight variation, diameter and thickness, and pharmacotechnological evaluations like friability and hardness by pharmaceutical standard methods from State Pharmacopoeia of Ukraine 2.0 (2.9.5, 2.9.7, 2.9.8). Selected samples had homogeneous physical parameters: average weight in the range of 6.98-7.00 g (none of the formulations had a deviation of more than ± 5%), diameter 3.51 cm, thickness 5.04-5.11 mm. The obtained values of hardness and friability (less than 1% for all formulations) indicate satisfactory mechanical strength of the dosage form. Stability study was carried out at (15-25) ⁰С and 60±5 % humidity rate and was determined by evaluating the appearance and pharmacotechnological parameters. The values of hardness and friability were constant throughout the storage period for all formulations. Stability studies indicated that the formulations № 1 and 2 were stable for 30 days. The present research allowed to develop formulations for obtaining a pleasant-tasting dosage form intended for relatively slow dissolution in the oral cavity – medicated lozenges for use in adolescents to alleviate the symptoms of catarrhal and aphthous stomatitis.