Search Results (6,081)

This study presents the results of investigating the interaction between the CeF₃–EuF₃ system and the NaCl–KCl salt melt using spectroscopic methods. It was found that CeF₃ ions undergo no significant changes upon dissolution in the NaCl–KCl melt. In contrast, the dissolution of EuF₃, both individually and within the CeF₃–EuF₃ system, is accompanied by redox reactions leading to the formation of Eu²⁺. The diffuse reflectance spectra of both the bottom (insoluble sediment) and upper parts of the solidified salt melt in the UV range indirectly indicate photoluminescence excitation from Ce³⁺ and Eu²⁺ ions. In addition, absorption bands in the near-IR region (1900–2300 cm⁻¹) confirm the retention of some Eu³⁺ ions in the salt melt. The study explored the effects of various factors—including sample composition, excitation wavelength, prior and subsequent heat treatment, and medium composition—on the excitation and emission spectra of the samples. Intense 5d-4f luminescence of Ce³⁺ and Eu²⁺ ions (at 330 and 430 nm, respectively) was observed predominantly in the upper part of the salt melts, along with much weaker 4f-4f luminescence from Eu³⁺ ions. Certain parameters were optimized to reduce the luminescence contribution from Ce³⁺ and especially Eu³⁺ ions while enhancing the luminescence of Eu²⁺ ions. Solidified salt solution-melts of the NaCl–KCl–CeF₃–EuF₃ system show promise as materials for developing solar ultraviolet radiation detectors. Full article

Hydrogenated amorphous carbon (a-C:H) has been considered a promising biocompatible coating to protect metallic alloys against corrosion for medical applications, namely orthodontics. However, there is still no optimal solution for this biomedical field; hence, the investigation remains open. In this work, the effect of a nonmetallic doping element (N) on sputter-deposited a-C:H coatings was studied concerning both salivary corrosion and cytotoxicity behavior. After a 30-day corrosion test in an acidic modified Fusayama-Meyer artificial saliva, metal release from both coated and uncoated 316L stainless steel (SS) substrates was quantified. Tests on the corrosion extracts were then performed by using monocultures of macrophages and fibroblasts, and their coculture; and cell viability was evaluated via the MTT test. Results show an overall inhibition of the SS corrosion, which enhanced the in vitro biocompatibility with a minimal effect on the coatings’ microstructure. Among all the coatings tested, the undoped a-C:H coating performed the best, whereas an increase in N doping led to poorer protection against metal dissolution and a subsequent slightly lower biocompatibility. The findings corroborate that selecting the nonmetallic element N for doping C-based coatings is not a good choice for this biomedical field, even at low contents up to 10 at.%. Full article

Many adsorbent materials are being studied for dye and oil removal from the environment. Bio-based materials such as silk are promising candidates due to their enhanced affinity for dyes and intrinsic hydrophobicity. This work extensively studies various silk textiles as dye and oil adsorbents. For comparison, we use electrospun fiber mats and hollow silk microparticle-treated silk fabrics. Our work is motivated by two factors: (i) massive amounts of silk waste is being discarded annually from textile factories, and (ii) the limited studies on the adsorption phenomena of pristine silk textiles. Based on our findings, 12 mg of silk filament yarn has a 90% methylene blue (MB) removal efficiency within 10 min of exposure for concentrations up to 100 ppm and exhibits adsorption capacities of 145 mg/g for 800 ppm concentrations. The adsorption kinetics obey a pseudo-second order, where the rate-controlling step is chemisorption, and isotherms follow the Langmuir model with homogenous monolayer adsorption. Furthermore, noil woven fabrics with contact angles of 140⁰ have oil adsorbent capacities that are double the fabric weight. Our work confirms that silk waste textiles are efficient and reusable bio-adsorbents for MB dye and oil removal, outperforming materials made with additional and energy-intensive techniques such as silk dissolution and electrospinning. Full article

Coastal blue carbon ecosystems sequester carbon, storing it as plant biomass and particulate organic matter in sediments. Recent studies emphasize the importance of incorporating dissolved inorganic and organic forms into carbon assessments. As sediment-stored organic matter decomposes, it releases dissolved inorganic carbon (DIC) and total alkalinity (TA), both of which are critical for regulating the partial pressure of CO₂ (pCO₂) and thus carbon sequestration. This study investigated the role of benthic DIC and TA fluxes in carbon sequestration within seagrass meadows in Dongsha Island’s inner lagoon (IL) during the winter and summer seasons. Chamber incubation experiments revealed elevated benthic DIC and TA fluxes compared to global averages (107 ± 75.9 to 119 ± 144 vs. 1.3 ± 1.06 mmol m⁻² d⁻¹ for DIC, and 69.7 ± 40.7 to 75.8 ± 81.5 vs. 0.52 ± 0.43 mmol m⁻² d⁻¹ for TA). Despite DIC fluxes being approximately 1.5 times higher than TA fluxes, water pCO₂ levels remained low (149 ± 26 to 156 ± 18 µatm). Mass balance calculations further indicated that benthic DIC was predominantly reabsorbed into plant biomass through photosynthesis (−135 to −128 mmol m⁻² d⁻¹). Conversely, TA accumulated in the water and was largely exported (−60.3 to −53.7 mmol m⁻² d⁻¹), demonstrating natural ocean alkalinity enhancement (OAE). This study highlights the crucial role of IL seagrass meadows in coastal carbon sequestration through net autotrophy and carbonate dissolution. Future research should explore the global implications of these processes and assess the potential of natural OAE in other coastal blue carbon ecosystems. Full article

Pearlitic steel rods are subjected to cold-drawing processes to produce pearlitic steel wires with true strains ranging from 0.81 to 2.18. Tensile tests are utilized to attain mechanical properties of cold-drawn pearlitic steel wires. TEM and XRD investigations were performed on the microstructure of the cold-drawn steel wires. With an increasing cold-drawn strain, both the interlamellar spacing and cementite lamellae thickness decrease, while the dislocation density significantly increases. The drawn wire has a tensile strength of 2170 MPa when the true stain reaches 2.18. Deformation-induced cementite dissolution occurs during cold-drawing progress, which releases many C atoms. The findings indicate that the supersaturation of C is heterogeneously distributed in the ferrite matrix. The ordered distribution of the released C in ferrite phases creates short-range order (SRO). SRO clusters and disordered Cottrell atmospheres contribute to solution strengthening, which, together with dislocation strengthening and interlamellar boundary strengthening, form an effective strengthening mechanism in cold-drawn pearlitic steel wires. Our work provides new insights into carbon redistribution and the mechanism of solution strengthening within ferrous phases. Full article

Background/Objectives: Interest in drug delivery systems (DDS) based on inorganic substrates has increased in parallel with the increase in the number of poorly water-soluble drugs. Hydroxyapatite is one of the ideal matrices for DDS due to its biocompatibility, low cost, and ease of preparation. Methods: We propose two doped hydroxyapatites, one with Ba on Ca sites another with Si on P sites, with the aim of improving the dissolution rate of piretanide, a diuretic, poorly water-soluble drug. The hybrids were characterized by different physical–chemical techniques, and their formation was demonstrated by infrared spectroscopy, thermal analysis, and electron microanalysis, as well as by comparing the results with those obtained on physical mixtures of HAPs and properly prepared piretanide. Results: Both the hybrids improved the piretanide dissolution rate compared with the physical mixtures and the drug alone. The dose was completely solubilized from the Si-doped hybrid in about 5 min in the three fluids considered. This remarkable improvement can be explained by an increase in the wettability and solubility of the drug loaded in the drug-carrier systems. Conclusions: Different experimental techniques, in particular spectroscopy and electronic microanalysis, proved the successful loading of piretanide onto doped HAP. Pharmaceutical measurements demonstrated rapid drug release in different fluids simulating gastrointestinal conditions after oral administration. These hybrid systems could be a very promising platform for drug delivery. Full article

The rare metals gallium and germanium are key strategic metals that are widely used in emerging industries. In this work, a novel hydroxamic acid extractant, BGYW, with low toxicity, was used for the selective solvent extraction of Ga ions and Ge ions from Zn, As, Cu, and Al ions in the solution from zinc smelting. The gallium and germanium ions were extracted efficiently under optimized conditions. Gallium ions were preferentially stripped using sulfuric acid, and germanium ions were stripped using an ammonium fluoride solution. Compared with the commercial extractant YW100, the dissolution loss of BGYW was reduced by 10 times. After 15 cycles, the germanium solvent extraction efficiency of BGYW remained at 100%, and the solvent extraction efficiency of gallium was about 98.7%, while the solvent extraction efficiency of both Ga ions and Ge ions using YW100 decreased to 20% after five cycles. This novel solvent extraction system exhibits considerable promise for application in zinc smelting processes for gallium and germanium solvent extraction. Full article

Famotidine is a histamine H2 receptor antagonist used in the treatment of gastrointestinal disorders. It is available in multiple formulations, including film-coated tablets, chewable tablets, oral suspension, and injections. The purpose of this study was to develop and evaluate the film-coated tablet (FT) containing famotidine, magnesium hydroxide, and precipitated calcium carbonate, designed to be pharmaceutically equivalent to the marketed chewable tablet (CT). To achieve the pharmaceutical equivalence of two tablets, the dissolution profiles of FT should be similar to those of CT. However, since CT is intended to be chewed before swallowing, testing it in its intact form would not provide accurate results. Therefore, pulverized chewable tablets (PCT) were used as the reference product. The dissolution, performed by the paddle method at 50 rpm, was analyzed by the validated UV method. Similarity factor (f₂) and difference factor (f₁) were calculated to assess the equivalence of the dissolution profiles. The results demonstrated that the dissolution profiles of the FT and CT were similar. Additionally, the acid-neutralizing capacity test confirmed the equivalence of the two antacids. This study is one of the first to propose that dissolution tests for pharmaceutical equivalence should be conducted on pulverized CTs when developing generic equivalents to CTs. Full article

A hybrid alginate hydrogel–chitosan nanoparticle system suitable for biomedical applications was prepared. Chitosan (CS) was used as a matrix for the encapsulation of lavender (Lavandula angustifolia) essential oil (LEO) and Mentha (Mentha arvensis) essential oil (MEO). An aqueous solution of an acidic Natural Deep Eutectic Solvent (NADES), namely choline chloride/ascorbic acid in a 2:1 molar ratio, was used to achieve the acidic environment for the dissolution of chitosan and also played the role of the ionic gelator for the preparation of the chitosan nanoparticles (CS-NPs). The hydrodynamic diameter of the CS-MEO NPs was 130.7 nm, and the size of the CS-LEO NPs was 143.4 nm (as determined using Nanoparticle Tracking Analysis). The CS-NPs were incorporated into alginate hydrogels crosslinked with CaCl₂. The hydrogels showed significant water retention capacity (>80%) even after the swollen sample was kept in the aqueous HCl solution (pH 1.2) for 4 h, indicating a good stability of the network. The hydrogels were tested (a) for their ability to absorb dietary lipids and (b) for their antimicrobial activity against Gram-positive and Gram-negative foodborne pathogens. The antimicrobial activity of the hybrid hydrogels was comparable to that of the widely used food preservative sodium benzoate 5% w/v. Full article

The porous particles prepared from composited calcium–ortho-phosphate (biphasic), Thai silk fibroin, gelatin, and alginate, with an organic to inorganic component ratio of 15.5:84.5, were tested for their abilities to control the release of the commercialized antibiotic solutions, clindamycin phosphate (CDP) and amikacin sulfate (AMK). The in vitro biodegradability tests complying to the ISO 10993-13:2010 standard showed that the particles degraded <20 wt% within 56 days. The drugs were loaded through a simple adsorption, with the maximum loading of injection-graded drug solution of 43.41 wt% for CDP, and 39.08 wt% for AMK. The release profiles from dissolution tests of the drug-loaded particles varied based on the adsorption methods used. The drug-loaded particles (without a drying step) released the drug immediately, while the drying process after the drug loading resulted in the sustained-release capability of the particles. The model-fitting of drug release profiles showed the release driven by diffusion with the first-ordered kinetic after the initial burst release. The released CDF and AMK from particles could sustain the inhibition of Gram-positive bacteria and Gram-negative bacteria, respectively, for at least 72 h. These results indicated the potential of these composited particles as controlled-release carriers for CDP and AMK. Full article

The hydrogeochemical properties and evolution of groundwater in the Essaouira syncline basin in northwestern Morocco were investigated in this study, with a total of 447 samples during different campaigns (April 2017, May 2018, March 2019, and July 2020). These samples were analyzed for major ions and stable and radioactive water isotopes (δ²H, δ¹⁸O, and ³H). With decreasing rainfall from climate change in Morocco, it is crucial to assess the sustainability of groundwater reserves. This shortage leads to the degradation of water and soil quality. To ensure sustainable water management and preserve the environment in the study area, it is necessary to assess groundwater quality for drinking and irrigation, take precautions, and establish management plans. This study assessed groundwater quality using two water quality index methods (WQI and IWQI). Several natural processes control groundwater mineralization, including the dissolution of evaporite and carbonate minerals, cation exchange phenomena, evaporation, and seawater intrusion. According to the results obtained using the WQI method, all groundwater samples in the study area are generally of poor quality and must be treated before being used for domestic purposes. Based on the results obtained by the IWQI method, the samples are suitable for use as irrigation water, especially for plants resistant to high salinity concentrations. Stable isotope measurements (δ²H and δ¹⁸O) indicate that Atlantic precipitation continuously recharges the recharge areas of the Essaouira Basin. Thus, the low values of tritium (³H) in groundwater mean that the freshwater in the Essaouira Basin is ancient. Full article

The effects of tensile and compressive strain, originating from U-bent deformation, on the corrosion behavior of 304 L stainless steel were studied via analyses of the material’s microstructure and electrochemistry in a 3.5% NaCl solution. In contrast with the as-received 304 L steel with the largest grain size, the deformed 304 L material with a small grain size had the lowest number of Σ3 grain boundaries and an overall low fraction, with special low-Σ values (≤29). Moreover, the dislocation density increased to 1.13 × 10¹⁶/m² and 1.4 × 10¹⁶/m² for the tensile and compressive 304 L steel testing, respectively. The decrease in E_pit and increase in i_pit suggested that there was a decrease in anti-corrosion properties due to tensile and compressive deformation. This might be attributed to the higher plastic strain found in deformed 304 L steel, which can induce the rupture of passive film and have a harmful influence on corrosion resistance. In particular, the compressive 304 L steel with the highest content of deformed grains (42.12%) promoted the formation of microgalvanic cells, thereby facilitating the nucleation of pits. Then, these pits grew to a large size through grain shedding. Subsequently, massive chloride ions were generated during metal dissolution and diffused along grain boundaries, which promoted the initiation and propagation of intergranular corrosion cracks. Full article

Grinding conditions affect the flotation of copper sulphide minerals as changes in the properties of the grinding media and their interactions with the sulphide minerals, and between sulphide minerals themselves, affect the chemical environment in the flotation pulp. Galvanic interactions between steel grinding media and sulphide minerals, and between sulphide minerals, can lower the pulp potential, decrease the dissolved oxygen concentration in the mineral slurry, and lead to the dissolution of iron and copper from the media and the minerals. As a result, the formation of hydrophilic iron hydroxides and their adsorption on the copper sulphide minerals can be deleterious to copper flotation while pyrite (when present) can be activated to flotation by dissolved copper lowering the grade of the copper concentrate. Electrochemically less active grinding media (e.g., chrome alloy balls rather than mild steel media) can have beneficial effects on flotation performance due to the lower oxidation of the grinding media and consequently the lower production of oxidised iron species in the pulp. Copper activation of pyrite can be decreased by chemical additions to the pulp. In this paper, relevant experimental data published in the last 15 years are discussed. Full article

Background/Objectives: Chronic skin wounds (CSWs) are a worldwide healthcare problem with relevant impacts on both patients and healthcare systems. In this context, innovative treatments are needed to improve tissue repair and patient recovery and quality of life. Cord blood platelet lysate (CB-PL) holds great promise in CSW treatment thanks to its high growth factors and signal molecule content. In this work, thermo-sensitive hydrogels based on an amphiphilic poly(ether urethane) (PEU) were developed as CB-PL carriers for CSW treatment. Methods: A Poloxamer 407^®-based PEU was solubilized in aqueous medium (10 and 15% w/v) and added with CB-PL at a final concentration of 20% v/v. Hydrogels were characterized for their gelation potential, rheological properties, and swelling/dissolution behavior in a watery environment. CB-PL release was also tested, and the bioactivity of released CB-PL was evaluated through cell viability, proliferation, and migration assays. Results: PEU aqueous solutions with concentrations in the range 10–15% w/v exhibited quick (within a few minutes) sol-to-gel transition at around 30–37 °C and rheological properties modulated by the PEU concentration. Moreover, CB-PL loading within the gels did not affect the overall gel properties. Stability in aqueous media was dependent on the PEU concentration, and payload release was completed between 7 and 14 days depending on the polymer content. The CB-PL-loaded hydrogels also showed biocompatibility and released CB-PL induced keratinocyte migration and proliferation, with scratch wound recovery similar to the positive control (i.e., CB-PL alone). Conclusions: The developed hydrogels represent promising tools for CSW treatment, with tunable gelation properties and residence time and the ability to encapsulate and deliver active biomolecules with sustained and controlled kinetics. Full article

The effect of the dry–wet cycle, characterized by periodic water level changes in the Three Gorges Reservoir, will severely degrade the bearing performance of rock formations. In order to explore the effect of the dry–wet cycle on the mesoscopic damage mechanism of jointed sandstone, a list of meso-experiments was carried out on sandstone subjected to dry–wet cycles. The pore structure, throat features and mesoscopic damage evolution of jointed sandstone with the action of the dry–wet cycle were analyzed using a-low-field nuclear magnetic resonance (NMR) technique. Subsequently, the impact on the mineral content of dry–wet cycles was studied by small angle X-ray scattering (SAXS). Based on this, the mesoscopic damage mechanism of sandstone subjected to dry–wet cycles was revealed. The results show that the effects of the drying–wetting cycle can promote the development of porous channels within sandstone, resulting in cumulative damage. Besides, with an increase in dry–wet cycles, the proportion of small pores and pore throats decreased, while the proportion of medium and large pores and pore throats increased. The combined effects of extrusion crush, tensile fracture, chemical reaction and dissolution of minerals inside the jointed sandstone contributed to the development of mesoscopic pores, resulting in the increase of porosity and permeability of rock samples under the dry–wet cycles. The results provide an important reference value for the stability evaluation of rock mass engineering under long-term dry–wet alternation. Full article