Physicochemical Interactions Research Articles

Developing carbon dots as green modifiers for improving the bonding performance of low-molar-ratio urea-formaldehyde resin

Reducing formaldehyde-to-urea molar ratio is conducive to improving environmental-friendliness of urea-formaldehyde (UF) resin-bonded wooden products, but at the expense of bonding performance, such contradictoriness is intrinsically due to the decreased cohesion of resin polymer structures. In this study, we proposed a novel strategy to enhance the bonding performance of low-molar-ratio UF resins by use of carbon dots (CDs) as green modifiers. Taking advantages of surface-contained plentiful carboxyl and hydroxyl groups, the synthesized CDs could generate strong physicochemical interactions with polymer segments and further improve cohesion of resin matrix. The optical microrheology demonstrated that the microscopic viscoelasticity of CDs-modified UF resin was increased as increasing of CDs content due primarily to the formation of strong hydrogen bonding interactions between CDs and resin polymers. Based on the analysis for curing behavior, the polycondensation reactivity of resin oligomers was almost free from the interaction or connection between CDs and polymer segments. Furthermore, as confirmed by nanoindentation technology, the physicochemical interactions formed between oxygenous functional groups of CDs and polymer matrices could improve the cohesion of resin after curing reaction, thus resulting in the enhanced micromechanical strength of wood-resin interphase and further bonding strength of resin at macroscopic level. Remarkably, this reinforcing effect imparted by CDs resulted in the tensile shear strength of plywood increased to 0.96 MPa, which was 77.8% increase in comparison to the panels bonded with unmodified resin and largely exceed the requirement given by national standard (0.7 MPa for plywood type Ⅱ). Taken together, this work demonstrated that the synthesized CDs are efficient and provided a potential platform for improving the bonding performance of low-molar-ratio UF resins.

Comprehensive treatment of aroma chemicals industrial effluent with substantial COD content by a novel PVP/polyamide composite hydrophilized RO membrane

A hydrophilized polyvinyl pyrrolidone/polyamide composite high rejection reverse osmosis (HPA-HR RO) membrane was used for the treatment of aroma chemicals containing effluent coming as multiple effect evaporators (MEE) condensate at UK Aromatics Pvt. Ltd., Boisar, Maharashtra. The unique membrane has an active composite layer of polyamide prepared by interfacial polymerization of high diamine (3%) and acid chloride (0.2%) monomer concentrations, which is further coated with polyvinyl pyrrolidone (PVP) to enhance hydrophilicity and chemical inertness. The plant provides removal of total dissolved solids (TDS) from 2500 to 3500 ppm in the feed to a value of 50–100 ppm in the permeate water indicating a rejection of more than 95% of the dissolved solids, with a high water recovery of 80% in permeate. Similarly, complete rejection of color was observed from dark brown to colorless (transparent), whereas the COD content was brought down from 3000 to 5000 mg/L in the MEE condensate to around 1000 mg/L indicating removal of 60 % to 80% depending upon the pressure applied to overcome the high osmotic pressure of the effluent. Physicochemical interactions between the PVP and polyamide skin layers of the composite membrane make the separating barrier durable and highly hydrophilic. Water would have greater sorption due to high affinity with the membrane and higher diffusion coefficient from its smaller size, while the less polar esters that constitute most of the COD would have low interaction and their larger molecular sizes make them less diffusive. The recovered permeate water has been reused in various internal industrial applications like cooling towers, cleaning, etc. at UK Aromatics.

APPLICATION OF COAL FLY ASH-BASED SORPTION MATERIALS IN HIGHLY MINERALIZED WASTEWATER TREATMENT

The results of the study showed that Ukrainian coal fly ash (CFA) and acid mine drainage (AMD) can be successfully processed into zeolite-like sorptive material (ZSM) to extract pollutants from AMD. This approach provides a twofold benefit: firstly, the interaction between CFA with AMD provides an alternative method of conditioning AMD. Secondly, the solid residues contain a lot of Al and Si so they can be used for the synthesis of ZSM. The synthesis was done via alkaline conversion followed by hydrothermal crystallization. ZSM can be effectively used as an ion exchanger and sorbent for the conditioning of highly saline wastewater. Mercury, which is considered a priority pollutant, can be removed to levels below the permission level. Anion species were also removed from the solution by mechanisms other than ion exchange, e. g. arsenic.
 Studies discovered the following results:
 - pH plays a key role in the formation of metal ions as well as the charge of the surface functional groups of the ZSM, thus changing the physicochemical interactions between the ZSM and pollutant ions.
 - in addition to ion exchange, other mechanisms are also suggested, including adsorption, and the formation of complex compounds that significantly contribute to the purification process.
 Given its simplicity, this technology can be implemented as the first stage in the treatment of metal-containing wastewater at an operating or decommissioned coal mining enterprise. This technology can also be implemented as part of the desalination stages at TPP treatment plants. The proposed method is based on waste utilization, so it can be considered an eco-friendly low-cost method of wastewater treatment. However, on an industrial scale, hydrothermal activation will lead to increased operating costs due to increased energy consumption. Therefore, future research should be conducted on the application of ZSM in a pilot plant.
 Since this technology can be applied to the removal of both cations and anions, it will undoubtedly attract interest, provided the synthesis technology is optimized. First of all, it is necessary to optimize the synthesis method in order to use low-temperature activation methods to lessen operating costs.

In vitro, in-vivo, and in-silico investigation of physicochemical interactions between pioglitazone and rifampicin

There is a possibility of in-situ physicochemical interactions between concomitantly administered drugs. This study aimed to investigate such physicochemical interactions between pioglitazone and rifampicin. Pioglitazone exhibited significantly higher dissolution in the presence of rifampicin, while the dissolution of rifampicin remained unaffected. The solid-state characterization of precipitates recovered after pH-shift dissolution experiments revealed the conversion of pioglitazone into an amorphous form in the presence of rifampicin. The Density Function Theory (DFT) calculations showed the intermolecular hydrogen bonding between rifampicin and pioglitazone. In-situ conversion of pioglitazone in amorphous form and subsequent supersaturation of GIT milieu translated into significantly higher in-vivo exposure of pioglitazone and its metabolites (M-III and M-IV) in Wistar rats. Therefore, it is advisable to consider the possibility of physicochemical interactions between concomitantly administered drugs. Our findings may be beneficial in tailoring the dose of concomitantly administered drugs, particularly for chronic conditions that entail polypharmacy.

Physicochemical interactions between amorphous metal oxide and polymer in metal–polymer hybrid materials

Laser–induced amorphous metal oxide is increasingly applied to enhancing interfacial bonding in metal–polymer hybrid materials. This work aims to explore physicochemical interactions between amorphous metal oxide and polymer to understand its bonding mechanism from the micro–nano scale. Scanning electron microscopy and X–ray photoelectron spectroscopy were used to investigate the physicochemical properties of laser–induced amorphous aluminum oxides on aluminum alloy surfaces. A well–infiltrated hybrid layer of incompletely oxidized amorphous aluminum oxides and polymer at enhanced aluminum alloy–polymer interface was characterized using transmission electron microscopy. Subsequently, molecular dynamics simulations and density functional theory calculations were utilized to explore the physicochemical interaction process between amorphous aluminum oxides and polymers and its role at aluminum alloy–polymer interface. It was demonstrated that amorphous aluminum oxides generate strong electrostatic interactions with polymer, and ionic and ionic–covalent bonds are the main chemisorption under low reaction energy barrier, which reveals the origin of the favorable infiltration and high reactivity of amorphous aluminum oxides. Furthermore, the bonding mechanism of aluminum alloy–polymer interface is clarified based on the discovery of interfacial anchoring effect resulting from the physicochemical interaction between amorphous aluminum oxides and polymer.

Thermo-Chemical Modification of Cellulose for the Adsorptive Removal of Titan Yellow from Wastewater.

This research work focuses on the isolation and thermo-chemical modification of cellulose and its application as an adsorbent for the removal of organic pollutants. The used cellulose was collected from a locally available plant (Olive Europa) commonly called Zaitoon. The stem branches of Zaitoon were collected and then kept in water for 40-45 days at room temperature to extract the cellulose fibers. These cellulose fibers were then kept in the Soxhlet apparatus for washing in n-hexane for 72 h. The purified cellulose was divided into three parts: one part was subjected to thermal activation (TAC), the second was modified chemically (CMC) with Benzyl Chloride, while the last one remained un-functionalized (UFC). All the three forms of cellulose were characterized via FTIR and SEM, then utilized for the removal of Titan Yellow (TY) dye from aqueous media via adsorption process by varying the contact time, temperature, concentration of dye and type, and dose of adsorbent. The adsorption efficiencies of all adsorbents were compared under different experimental variables. Thermally activated cellulose showed the best results for the removal of TY compared with other materials. The calculated removal percentage of TY was found to be 97.69, 94.83, 94.83, and 98% under equilibrium conditions of contact time, temperature, adsorbent dose, and TY concentration. Similarly, the uptake capacities of TAC under optimal experimental conditions were found to be 19.56, 18.96, 18.52, and 18.75 mg/g. Thermodynamic studies of TAC, CMC, and UFC showed that the values of ΔG are negative, while those of ΔH and ΔS are positive in all cases and at all temperatures. This indicates that the TY elimination process is endothermic and spontaneous with an entropy-driven nature. The obtained results indicate that the as-fabricated low-cost biomaterials can effectively remove dyes from wastewater through physicochemical interactions. The removal process was influenced by the nature of the adsorbent and the operating variables.

Magnetic Solid-Phase Extraction of Fipronil from Aqueous Solution and Eggshells Using Amine-Coated Iron Oxide Nanoparticles.

Fipronil, as a broad use insecticide, is regulated under directives and standards in many countries since it is classed as Class II moderately hazardous pesticide and Group C possible human carcinogen. In this study, amine coated iron oxide (NH2 -Fe3 O4 ) is used as a new adsorbent with high adsorption capacity in the removal of fipronil from aqueous solution and eggshells.The adsorption performance was studied through batch adsorption under different concentrations of fipronil (10-200 μg/mL), different nanoparticles amount (0.1-1 mg) at different pH (4.5-6.0) and temperature (25-75 °C). Results showed that NH2 -Fe3 O4 nanoparticles (0.1 mg) have excellent adsorption efficiency (97.06 %) at 25 °C, and pH 5.5. It also showed higher adsorption capacity towards fipronil sulfide, fipronil sulfone and fipronil desulfinyl with removal efficiencies of 92.82 %, 86.35 % and 76.24 % from aqueous solution and 97.62 %, 76.97 % and 62.65 % from eggshells, respectively. Fipronil adsorption process on NH2 -Fe3 O4 nanoparticles showed best fitting to Langmuir adsorption isotherm indicating monolayer chemical adsorption by physicochemical interactions spontaneously on homogenous surfaces. Having higher adsorption capacity and reusability NH2 -Fe3 O4 nanoparticles were shown to be effective adsorbents for removal of fipronil from aqueous solution and eggshells.

Electrically driven wetting of high-entropy (Zr1/3Hf1/3Ce1/3)1-x(Y1/2Gd1/2)xO2-δ ceramics by molten Cu

For the first time, the wettability of fluorite-type high-entropy (Zr1/3Hf1/3Ce1/3)1-x(Y1/2Gd1/2)xO2-δ (δ = 0.05‒0.3) ceramics by molten Cu under a direct current (DC) was investigated. The wetting behavior depended noticeably on the stoichiometry (x = 0.1‒0.6) of the metal components in (Zr1/3Hf1/3Ce1/3)1-x(Y1/2Gd1/2)xO2-δ. The initial contact angle increased with x. For x ≥ 0.4, DC application improved the wettability, and the final contact angle decreased with increasing x. The wettability improvement was mainly attributed to the diffusion of high-entropy metal components into the Cu melt and the formation of an interfacial product. The relatively weak Ce‒O and Gd‒O bonds were dissociated more easily, and Ce and Gd diffused more rapidly than Zr, Hf and Y and thereby influenced the wettability more prominently. This work is expected to advance the understanding of interfacial physicochemical interactions between metal melts and high-entropy oxides and provide a reference for joining high-entropy oxides with metals under an electric field.

3D-Printed Gastroretentive Tablets Loaded with Niclosamide Nanocrystals by the Melting Solidification Printing Process (MESO-PP).

Niclosamide (NICLO) is a recognized antiparasitic drug being repositioned for Helicobacter pylori. The present work aimed to formulate NICLO nanocrystals (NICLO-NCRs) to produce a higher dissolution rate of the active ingredient and to incorporate these nanosystems into a floating solid dosage form to release them into the stomach slowly. For this purpose, NICLO-NCRs were produced by wet-milling and included in a floating Gelucire l3D printed tablet by semi-solid extrusion, applying the Melting solidification printing process (MESO-PP) methodology. The results obtained in TGA, DSC, XRD and FT-IR analysis showed no physicochemical interactions or modifications in the crystallinity of NICLO-NCR after inclusion in Gelucire 50/13 ink. This method allowed the incorporation of NICLO-NCRs in a concentration of up to 25% w/w. It achieved a controlled release of NCRs in a simulated gastric medium. Moreover, the presence of NICLO-NCRs after redispersion of the printlets was observed by STEM. Additionally, no effects on the cell viability of the NCRs were demonstrated in the GES-1 cell line. Finally, gastroretention was demonstrated for 180 min in dogs. These findings show the potential of the MESO-PP technique in obtaining slow-release gastro-retentive oral solid dosage forms loaded with nanocrystals of a poorly soluble drug, an ideal system for treating gastric pathologies such as H. pylori.

Effects of erosion and deposition on the extent and characteristics of organic carbon associated with soil minerals in Mollisol landscape

The physicochemical interactions between soil organic carbon (SOC) and minerals are important for the long-term stabilization of OC. However, in the dynamic landscape, the mechanisms of OC stabilized by different types of minerals remains unclear. Herein, we investigated the effects of erosion and deposition on the distribution of SOC pools and the interaction of OC with different minerals in an agricultural Mollisol landscape. We quantified the SOC fractions using a physically separated technique and measured the polyvalent cation bound-OC using a mineral reduction release method. Sorption experiments and specific mineral surface area (SSA) were determined. Results show that 77.6%−96.9% of SOC was mineral-associated OC (MAOC). MAOC contents in the topsoil (0–20 cm) and subsoil (60–80 cm) of the depositional sites were 1.17 and 1.64 times higher than those in the topsoil and subsoil of the eroding sites, respectively. A higher MAOC content in the depositional sites suggests that MAOC in the middle slope migrates directly to the downslope through erosion, and subsequent depositional and burial processes promote OC interactions with minerals. Furthermore, Fe and Al oxides were the main minerals that stabilized OC compounds at each slope, while Ca played a vital role in OC interactions in the depositional sites. The Fe- and Al-bound OC (Fe/Al-OC) showed higher aromaticity, humification, and molecular weight than Ca-OC and bulk soil dissolved OC, which remained unaffected by erosion and deposition. These OC interactions with Fe/Al increased the chemical structural stability of SOC. Furthermore, the depositional sites showed the highest MAOC contents, MAOC loading, BET-C constant, adsorption capacity, and the lowest SSA covered by SOC (%SSASOC-covered). These results indicate that depositional sites have the highest capacities for OC sequestration. Based on these results, the deposition or burying of eroding OC plays a key role in stabilizing soil OC.

Probing the physicochemical interactions between thermo-thickening polymers and clay fluids for improve rheological performance

The field of thermo-thickening polymer interacting with clay has long been shrouded in mystery and ambiguity. Despite numerous studies and investigations, the complex interactions, underlying mechanism and binding forces remain elusive, imposing further exploration and elucidation. In this study, three thermo-thickening polymers such as poly(acrylamide methylpropane sulfonic acid-co-N-vinylcaprolactam) (PNV), poly(acrylamide methylpropane sulfonic acid-co-N,N-dimethylacrylamide) (PDM), and poly(acrylamide methylpropane sulfonic acid-co-N-isopropylacrylamide) (PNP) with clay fluids (CFs) were investigated to gain deeper understanding of the underlying physicochemical interactions. Techniques such as Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR), and elemental analysis (EA) elucidated the structural properties, whereas turbidimetry and rheometric analysis elucidated the temperature-induced phase transitions. The interactions between the different polymer side chains and clay double-sheets were investigated through isothermal adsorption testing, probing chemisorption and hydrogen bonding tuned the chemical properties, whereas electrostatic forces (ionic/van der Waals) bind the physical properties as demonstrated by Zeta (ζ) potential, XRD, high-resolution spectroscopy (XPS), and scanning electron microscopy (SEM) imaging. The addition of 0.2–1.5 wt% of the polymers induced significant effect on the rheological properties of CFs, with increase in low shear viscosity and plastic viscosity, attributed to the formation of gel-like structures at high temperatures. PNV/Clay (NVBF)-modified fluid demonstrated exceptional fluid thickening and suspension behaviors compared to linear PDM/Clay (DMBF) and PNP/Clay (NPBF)-modified fluids. In addition, NVBF exhibited significantly higher adsorption energies and basal spacings, along with more crystalline patterns suited to embed clay particles. Overall, the synergistic effect of the different polymer side chains with clay particles provides valuable insights on the mechanistic and enhancement of rheological properties of CFs effective as shale inhibition, viscosifier and wellbore stabilization.

Larval Settlement on Marine Surfaces: The Role of Physico-Chemical Interactions

Biofouling is the association of sessile aquatic organisms that rapidly settle on artificial hard substrata, thereby posing a large problem worldwide since its growth often causes severe damage to submerged structures [...]

The comparison between zein-anthocyanins complex and nanoparticle systems: Stability enhancement, interaction mechanism, and in silico approaches

This research aimed to compare and characterize the physicochemical properties and interaction mechanism of zein and anthocyanins (ACNs) from experimental and theoretical perspectives. Zein-ACNs complex (ZACP) was prepared by mixing ACNs with different concentrations of zein, and zein-ACNs nanoparticles (ZANPs) were formed using ultrasound-assisted antisolvent precipitation method. The hydrated particle sizes of the two systems were 590.83 nm and 99.86 nm, respectively, and observed to be spherical under transmission electron microscopy (TEM). The multi-spectroscopy approaches confirmed hydrogen bonding and hydrophobic forces were the dominant forces for stabilizing ACNs. The retention of ACNs, color stability and antioxidant activities were also improved in both systems. Furthermore, molecular simulation results were consistent with the multi-spectroscopy findings, which clarified the contribution of van der Waals forces to the binding of zein and ACNs. This study provided a practical approach for stabilizing ACNs and expanding the utilization of plant proteins as stabilization systems.

Highly dispersed PtO over g-C3N4 by specific metal-support interactions and optimally distributed Pt species to enhance hydrogen evolution rate of Pt/g-C3N4 photocatalysts

Understanding the fundamental chemistry of metal-support interactions during catalyst preparation is essential to develop a highly efficient Pt/g-C3N4 photocatalyst for the H2 evolution reaction (HER). In this study, we prepared Pt/g-C3N4 photocatalysts via a loading process of different Pt contents onto solvothermally treated g-C3N4 (SCN) and a successive hydrogen reduction. The physicochemical interactions between Pt species and O-containing functional groups over SCN were tracked, and we investigated how the interactions influenced the photocatalytic properties and performance of Pt/SCN. During the reduction process, Pt(OH)22+ ions in liquid phase specifically interacted with neighboring C = O groups over SCN, resulting in highly dispersed PtO species via chemical bonding to SCN. Due to the limited number of the neighboring C = O groups over SCN, the chemically bonded PtO species were saturated at a certain amount, and 1Pt/SCN (1 wt% of Pt) showed the highest Pt dispersion in this study. In the reduction process, excess Pt was readily reduced to Pt metallic phase and then agglomerated in Pt clusters at high Pt loadings. Therefore, the highly active and stable Pt2+ sites were uniformly dispersed and immobilized over 1Pt/SCN by specific interactions with the O-containing functional groups, showing an outstanding HER activity per gram Pt (120.6 mmol∙gPt−1∙h−1). However, data for the optical and electrochemical properties demonstrated that 3Pt/SCN (3 wt% of Pt) had the best charge separation efficiency because of the optimal distribution of the Pt species over SCN. Correspondingly, the optimized 3Pt/SCN exhibited the highest HER rate of 1255.52 μmol∙gcat−1∙h−1, which was about 50 times higher than SCN photocatalyst (25.2 μmol∙gcat−1∙h−1).

Eco-Friendly AMPS-Doped Polyaniline/Urethane-Methacrylate Coating as a Corrosion Protection Coating: Electrochemical, Surface, Theoretical, and Thermodynamic Studies

In this study, 2-acrylamido-2-methylpropanesulfonic acid (AMPS)-doped polyaniline (PANI) fibers were used as polymerizable smart anticorrosive agents to prepare eco-friendly UV-curable anticorrosive coatings. For this purpose, AMPS-doped PANI fibers were synthesized through chemical oxidative interfacial polymerization. The size and chemical structure of the prepared conducting fibers were characterized by scanning electron microscopy, 1H NMR, and Fourier transform infrared (FTIR) analyses. As a binder for the prepared conducting fibers, an eco-friendly fluorinated urethane-methacrylate dispersion was synthesized and fully characterized using FTIR analysis. Subsequently, various amounts of the synthesized fibers were mixed with the fluorinated binder to prepare UV-curable anticorrosive coatings. The physicochemical interactions between the PANI fibers and UV-curable binder were studied thoroughly using differential scanning calorimetry and thermogravimetric analyses and measurement of the gel contents and adhesion strength of the prepared composite coatings. The corrosion resistance performance of the prepared coatings was evaluated using electrochemical impedance spectroscopy analysis, and the obtained results revealed that the presence of 2 wt % of the AMPS-doped PANI fibers significantly enhanced the corrosion resistance of the obtained coating. In addition, the corrosion layers of the coatings were analyzed using X-ray photoelectron spectroscopy, which indicated that the AMPS-doped PANI fibers changed the composition of the corrosion product layer. To expand these attempts, this study also explores the interaction of AMPS-doped PANI fibers with the Fe(100) surface using density functional theory as well as atom in molecule calculations. All of the obtained results proved that the outstanding corrosion protection performance of the prepared composite coatings originated from exceptional chemical interactions between the unsaturated doping agents of the prepared PANI fibers and the UV-cured polymer.

Effect of Molecular Weight on the Dissolution Profiles of PEG Solid Dispersions Containing Ketoprofen

Solid dispersions are typically binary systems with a hydrophilic matrix polymer and a lipophilic active substance. During formulation, the drug undergoes a crystalline to amorphous phase transition, which leads to a supersaturated solution providing enhanced bioavailability. The interaction of the active substance and the polymer is unique and influences the level of supersaturation. We aimed to investigate the relationship between low molecular weight polyethylene glycol derivates PEG 1000, 1500, and 2000 and ketoprofen regarding the effect of molecular weight. The physicochemical properties of solid dispersions prepared with hot melt homogenization and their respective physical mixtures were investigated with Fourier transform infrared spectroscopy, powder X-ray diffraction and scanning electron microscopy techniques. A phase solubility study was carried out in hydrochloric acid media which showed no difference between the three polymers, but the dissolution curves differed considerably. PEG 1000 had higher percentage of released drug than PEG 1500 and 2000, which had similar results. These results indicate that when multiple low molecular weight PEGs are suitable as matrix polymers of solid dispersions, the molecular weight has only limited impact on physicochemical characteristics and interactions and further investigation is needed to select the most applicable candidate.

In depth characterization of physicochemical critical quality attributes of a clinical drug-dendrimer conjugate

A deep and detailed understanding of drug-dendrimer conjugates key properties is needed to define the critical quality attributes that affect drug product performance. The characterization must be executed both in the formulation media and in biological matrices. This, nevertheless, is challenging on account of a very limited number of suitable, established methods for characterizing the physicochemical properties, stability, and interaction with biological environment of complex drug-dendrimer conjugates. In order to fully characterize AZD0466, a drug-dendrimer conjugate currently under clinical development by AstraZeneca, a collaboration was initiated with the European Nanomedicine Characterisation Laboratory to deploy a state-of-the-art multi-step approach to measure physicochemical properties. An incremental complexity characterization approach was applied to two batches of AZD0466 and the corresponding dendrimer not carrying any drug, SPL-8984. Thus, the aim of this work is to guide in depth characterization efforts in the analysis of drug-dendrimer conjugates. Additionally, it serves to highlight the importance of using the adequate complementary techniques to measure physical and chemical stability in both simple and biological media, to drive a complex drug-dendrimer conjugate product from discovery to clinical development.

Development of Delayed-Release Matrix Tablets Comprising Solid Dispersion of Mefenamic Acid

Mefenamic acid (MA), a member of nonselective nonsteroidal anti-inflammatory drugs (NSAIDs), has been widely use to relief pain and inflammation. Its medical uses are limited by poor aqueous solubility resulting in low bioavailability and gastric irritation. The aim of this study was to develop a mefenamic acid delayed-release matrix tablet formulation using solid dispersion (SD). Delayed-release drug delivery systems were designed to retard drug release in upper gastrointestinal tract avoiding gastrointestinal (GI) adverse reactions. SDs of MA were successfully prepared by solvent evaporation method employing methanol as a solvent. SDs incorporated surfactant and super disintegrant gave much higher rates of dissolution than SDs with combined carriers (PEG and surfactant), SD containing PEG and pure drug, respectively. The optimal SD containing MA:PEG4000:poloxamer188:crospovidone in the ratio 1:8:1:3 exhibited higher amount of drug release up to 8-fold compared with pure MA. FTIR and DSC were performed to identify the physicochemical interaction between drug and polymers. The resulting data justified that no change in the chemical structure of MA and the crystalline MA transformed into the amorphous state after preparation. The formulation F4 delayed-release tablet comprising SD of MA dissolved less than 4 % in artificial gastric fluid in the initial 2 h and released more than 95 % at 3 h in the artificial intestinal fluid. Accordingly, formulation F4 containing polyethylene oxide as a time-controlled matrix-forming polymer was a promising delayed-release solid dispersion system of MA. HIGHLIGHTS The present study demonstrated a mefenamic acid delayed-release matrix tablet formulation using solid dispersion (SD) The optimal SD of mefenamic acid exhibited higher amount of drug release (8-fold) compared with that of the pure drug The tablet formulation F4 containing polyethylene oxide is capable of releasing mefenamic acid in a typical delayed-release profile GRAPHICAL ABSTRACT

Mixing of heat-insulating mixtures in pneumatic mixer with spiral energy carrying tube

Introduction. Mixing of dry components in mixers is one of the most important stages of any technological process in the manufacture of a composite material. To date, various technologies use a wide variety of mixing equipment, which is characterized by different principles of mixing and design solutions. Of particular interest for the preparation of high-quality and homogeneous mixtures for heat-insulating purposes is a pneumatic mixer with a spiral energycarrying tube. The article presents the results of studies using the method of mathematical planning of the fullfactor ПФЭЦКРП24 experiment, which makes it possible to most adequately assess the ongoing processes while minimizing systematic errors.Materials and methods. In the work, ЦЕМ 0 42,5Н ГОСТ 31108–2020 Portland cement with a specific surface area of 308 m2 / kg, sand of the Volsky deposit were used as raw materials for testing. Expanded vermiculite obtained as a result of heat treatment of natural vermiculite at a temperature of about 700°C was used as a light filler.Results. Heat-insulating mixtures prepared in a pneumatic mixer with a spiral energy-carrying tube ensure the production of heat-insulating mortars with stable density values of 1420 kg/m3, having sufficient compressive strength of 3.3 MPa, and guarantee high heat-shielding properties in building structures.Conclusion. The developed design and the conducted studies made it possible to establish the high efficiency of the proposed mixer, which provides a uniform distribution of the particles to be mixed, high homogenization and the creation of conditions for accelerating the physicochemical interactions in the created mixture with subsequent mixing of the prepared mixture with water and the formation of the required internal structure of the created composites.

Glycosylation and Lipidation Strategies: Approaches for Improving Antimicrobial Peptide Efficacy.

Antimicrobial peptides (AMPs) have recently gained attention as a viable solution for combatting antibiotic resistance due to their numerous advantages, including their broad-spectrum activity, low propensity for inducing resistance, and low cytotoxicity. Unfortunately, their clinical application is limited due to their short half-life and susceptibility to proteolytic cleavage by serum proteases. Indeed, several chemical strategies, such as peptide cyclization, N-methylation, PEGylation, glycosylation, and lipidation, are widely used for overcoming these issues. This review describes how lipidation and glycosylation are commonly used to increase AMPs' efficacy and engineer novel AMP-based delivery systems. The glycosylation of AMPs, which involves the conjugation of sugar moieties such as glucose and N-acetyl galactosamine, modulates their pharmacokinetic and pharmacodynamic properties, improves their antimicrobial activity, and reduces their interaction with mammalian cells, thereby increasing selectivity toward bacterial membranes. In the same way, lipidation of AMPs, which involves the covalent addition of fatty acids, has a significant impact on their therapeutic index by influencing their physicochemical properties and interaction with bacterial and mammalian membranes. This review highlights the possibility of using glycosylation and lipidation strategies to increase the efficacy and activity of conventional AMPs.