Higher Dissolution Rate Research Articles

FORMULATION AND IN VITRO TESTS OF KETOPROFEN NANOSUSPENSION USING THE MILLING METHOD WITH POLYMER VARIATIONS

Objective: The aim of this research was to formulate ketoprofen nanosuspension with a variety of polymers and to compare the dissolution rate of the nanosuspensions with ketoprofen suspension. Methods: Ketoprofen nanosuspension was formulated by milling method using a different polymer such as Polyvinyl Pyrrolidone (PVP) K-30 (F1), Polyvinyl Alcohol (PVA) (F2) and Hydroxy Propyl Methyl Cellulose (HPMC) (F3). Nanosuspensions were prepared and characterized, including organoleptic, pH, particle size, zeta potential, Polydispersity Index (PI), specific gravity, crystalline state determination, physical stability at room temperature for 3 mo, and in vitro dissolution test compared with ketoprofen suspension. Results: The ketoprofen nanosuspensions with PVP K-30 and PVA showed stable preparations, while those with HPMC showed less stability, as indicated by sedimentation during storage. The particle size values of PVP K-30 and PVA were 10.004±0.03 nm; and 9.560±0.01 nm; zeta potential and polydispersity index values met the test requirements. The dissolution rate of the ketoprofen nanosuspensions was higher with a cumulative of F1, F2, and F3 were 83.35%; 85.00%, and 81.09% after 60 min, while the ketoprofen suspension was only 7.62%. Conclusion: The milling method of ketoprofen nanosuspensions with PVP and PVA has more stable physical characteristics than nanosuspension with HPMC. The ketoprofen nanosuspensions have a higher dissolution rate than the ketoprofen suspension.

Climate controls on speleothem initial 234U/238U ratios in midlatitude climate over two glacial cycles

Despite early hydrological studies of 234U/238U in groundwaters, their utilization as a paleoclimatic proxy in stalagmites has remained sporadic. This study explores uranium isotope ratios in 235 datings (230Th) from six stalagmites in Ejulve cave, northeastern Iberia, covering the last 260 ka. The observed 234U enrichment is attributed to selective leaching of 234U from damaged lattice sites, linked to the number of microfractures in the drip route and wetness frequency, which under certain conditions, may result in the accumulation of 234U recoils. This selective leaching process diminishes with enhanced bedrock dissolution, leading to low δ234U. Temperature variations significantly influence bedrock dissolution intensity. During stadial periods and glacial maxima, lower temperatures likely reduced vegetation and respiration rates, thereby decreasing soil CO2 and overall rock dissolution rates. This reduction could enhance the preferential leaching of 234U from bedrock surfaces due to lower bulk rock dissolution. Additionally, the temperature regime during cold periods may have facilitated more frequent freeze–thaw cycles, resulting in microfracturing and exposure of fresh surfaces. Conversely, warmer temperatures increased soil respiration rates and soil CO2, accelerating rock dissolution rates during interstadials and interglacials, when low δ234U is consistent with high bedrock dissolution rates. The contribution of a number of variables sensitive to bedrock dissolution and wetness frequency processes successfully explains 57 % and 74 % of the variability observed in the δ234U in Andromeda stalagmite during MIS 3–4 and MIS 5b-5e, respectively. Among these variables, the growth rate has emerged as crucial to explain δ234U variability, highlighting the fundamental role of soil respiration and soil CO2 in δ234U through bedrock dissolution. I-STAL simulations provides the potential for a combination of Prior Calcite Precipitation (PCP) indicators like Mg/Ca with PCP-insensitive indicators of bedrock dissolution such as δ234U, along with growth rate data, may be useful to diagnose when PCP variations reflect predominantly changes in drip intervals and when changes in bedrock dissolution intensity contribute. The relationship between stalagmite δ234U, bedrock dissolution, and initial dripwater oversaturation suggests two significant advancements in paleoclimate proxies. First, δ234U could serve as a valuable complement to δ13C since it is significantly influenced by soil respiration and soil CO2, thereby reflecting soil and vegetation productivity sensitive to both humidity and temperature. Secondly, since PCP does not fractionate uranium isotopes, δ234U could be used in combination with Mg/Ca or δ44Ca to deconvolve PCP variations due to changing drip rates from those due to changes in initial saturation state. This study emphasizes the overriding climatic control on δ234U, regardless of the absolute 234U/238U activity ratios among samples and their proximity or distance from secular equilibrium, and advocates for its application in other cave sites.

Comparing additives effects on bioleaching efficiency of Cd-bearing ZnS concentrate in mesophilic conditioning at high pulp density

The roasting-leaching-electrowinning (RLE) process is the most common method for processing sphalerite concentrate. However, this method has disadvantages that can affect the environment. Bioleaching is an eco-friendly method that can replace this method, but the low kinetics of this method is the main barrier to replacing it. In previous research, various additives have been used to solve this problem, but unfortunately, these additives have usually been investigated in low-density pulp, and very limited research has been conducted on the comparison between additives. In this study, the effect of graphite, silver (Ag+), L-cysteine, pyrite, elemental sulfur, and ferrous sulfate additives on the bioleaching of Cd-bearing sphalerite concentrate at 12 % density pulp has been investigated. The results showed that Ag + ions had a higher dissolution rate than the others, and in the optimal condition (60 mg/l), zinc and cadmium extractions were achieved at 82.6 % and 74.5 %, respectively. The bioleached residues have been investigated by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) analyses, and it was found that Ag+ ions cause the surface to become porous.

Multi-Parameter Experimental Investigation on the Characteristics of Acidizing Effectiveness in High-Temperature Carbonate Formation

Carbonate formation is the key reservoir in Sichuan Basin for natural gas development. Compared with the early stage of development, the burial depth of targeted formation becomes deeper, and the formation temperature gets higher. So, the characteristics of acidizing effectiveness in high-temperature carbonate formations make this evaluation slightly difficult. Currently, it is common that a single parameter is considered to study acidizing effectiveness by simulation and experiment methods. In this paper, for a more accurate investigation of acidizing effectiveness, multiple parameters, including permeability change rate, fracture conductivity, and surface roughness, were introduced by a series of experiments. It is revealed that the permeability change rate is more than 57% when using gelled acid. As the amount of diverting agent increases in diverting acid, the viscosity of the acid grows to its peak with the reaction, making it easier to block the high permeability core temporarily and divert to acidify the low permeability core, where the permeability change rate of the low permeability core goes from 51.6% to 64.2%, which shows well acidizing effectiveness. In addition, the short-term and long-term conductivity of the samples from the three different formations are more than 200 mD∙m under high closure stress. The conductivity of Maokou Formation is the largest due to its high content of carbonate minerals and high dissolution rate. And the results of long-term conductivity are consistent with those of surface roughness, making the evaluation results more reliable for acidizing effectiveness. It is worth noting that temperature is a factor that cannot be ignored in the evaluation of acidizing effectiveness because it has a great influence on the performance of the acid system, such as viscosity and the reaction-reduced rate, leading to an acidizing effectiveness affect. So, the temperature resistance of an acid system is important as well.

Modeling and comparison of dissolution profiles for different brands of albendazole boluses

BackgroundAddressing critical veterinary drugs, especially drugs with solubility problems like albendazole, and their implications for therapeutic efficacy, in-vitro dissolution studies can indeed provide valuable insights into how different brands of albendazole boluses perform under standardized conditions, helping to assess their dissolution profiles and potential bioavailability.MethodsSix brands of albendazole 300 mg boluses were collected from December 2020 to May 2021 G.C. The laboratory work was conducted from December 2020 to May 2021 in the National Animal Products and Veterinary Drugs and Feed Quality Assessment Centre (APVD-FQAC) laboratories. The collected brands from government veterinary clinics and private veterinary shops were subjected to model independent and dependent parameters. The dissolution test was conducted according to the USP monograph.ResultsThe study found that none of the six brands met the requirements of the dissolution test, as their API release was less than 80% within the specified 60-minute timeframe according to USP standards. Model independence indicated that only one brand (Alb002 = 3.72) achieved a difference factor of ≤ 15%. The remaining four brands (4/6) did not meet this criterion. However, the similarity factor (f2) revealed that all five brands (5/6) were comparable to the comparator products, with f2 values of \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:\\ge\\:$$\\end{document}50%. The mean dissolution time results confirmed that three brands (3/6) had the highest dissolution rate and the fastest onset of action. The model-dependent kinetics indicated that the Weibull and Korsemeyer-Peppas models were the best fit for the release of drug substances.ConclusionThe study highlights issues with albendazole boluses’ quality, highlighting the need for national in-vitro dissolution studies. These recommendations could improve quality control, streamline regulatory frameworks, and offer practical, cost-effective methods for evaluating drug efficacy and safety, ensuring veterinary pharmaceuticals meet safety and efficacy standards.

Preparation and Characterization of Dutasteride Nanoparticles as Oral Fast-Dissolving Film

Background: Dutasteride, is a drug whose mechanism of action is inhibition of the enzyme 5-alpha reductase. It has been approved for use in the treatment of benign prostatic hyperplasia. Dutasteride has low solubility and high permeability, which classifies it as Biopharmaceutics classification system class II, according to the Biopharmaceutics Classification System. It has a water solubility of only 0.038 ng/mL and a slow dissolving rate, resulting in its exclusive availability in the market as a formulation contained within soft gelatin capsules. Objective: The aim of this study involves two parts. First, is the enhancement of dutasteride dissolution rate, by the creation of dutasteride nanosuspension, and second is the enhancement of patient compliance by the transformation of this nanosuspension to oral fast-dissolving film, which is characterized by its fast disintegration, stability, and ease of administration. Methods: The solvent anti/solvent precipitation method was used to formulate dutasteride nanosuspension. In addition, dutasteride nanoparticles oral fast dissolving films were prepared by using the solvent casting method. To compare the in vitro release patterns of pure dutasteride film and selected dutasteride nanoparticles film, the statistical analysis for the dissolution investigation was conducted using the model-independent technique (employing similarity factor f2) utilizing a DD solver. The selected dutasteride nanoparticle film was supposed to be the test material, while the pure dutasteride film was supposed to serve as the reference. Results: dutasteride nanosuspension demonstrated a high enhancement of the dissolution rate. In addition, the prepared dutasteride nanoparticles oral fast-dissolving film exhibited a further increase in the rate of dissolution and fast disintegration, and the administration is easy, all of these properties making it a promising dosage form. Conclusion: Nanosuspension is an excellent approach for enhancing the solubility, dissolution rate, and effectiveness of drugs with limited aqueous solubility such as dutasteride. In addition, the oral fast-dissolving film can be considered a promising dosage form that will increase patient compliance due to its high dissolution rate, fast disintegration, and easy administration.

Computer-driven formulation development of Ginsenoside Rh2 ternary solid dispersion.

(20S)-Ginsenoside Rh2 is a natural saponin derived from Panax ginseng Meyer (P. ginseng), which showed significantly potent anticancer properties. However, its low water solubility and bioavailability strongly restrict its pharmaceutical applications. The aim of current research is to develop a modified (20S)-Ginsenoside Rh2 formulation with high solubility, dissolution rate and bioavailability by combined computational and experimental methodology. The "PharmSD" model was employed to predict the optimal polymer for (20S)-Ginsenoside Rh2 solid dispersion formulations. The solubility of (20S)-Ginsenoside Rh2 in various polymers was assessed, and the optimal ternary solid dispersion was evaluated across different dissolution mediums. Characterization techniques included the Powder X-ray diffraction (PXRD) and Fourier transform infrared spectroscopy (FTIR). Molecular dynamics simulations were employed to elucidate the formation mechanism of the solid dispersion and the interactions among active pharmaceutical ingredient (API) and excipient molecules. Cell and animal experiments were conducted to evaluate the in vivo performance of the modified formulation. The "PharmSD" solid dispersion model identified Gelucire 44/14 as the most effective polymer for enhancing the dissolution rate of Rh2. Subsequent experiment also confirmed that Gelucire 44/14 outperformed the other selected polymers. Moreover, the addition of the third component, sodium dodecyl sulfate (SDS), in the ternary solid dispersion formulation significantly amplified dissolution rates than the binary systems. Characterization experiments revealed that the API existed in an amorphous state and interacted via hydrogen bonding with SDS and Gelucire. Moreover, molecular modeling results provided additional evidence of hydrogen bonding interactions between the API and excipient molecules within the optimal ternary solid dispersion. Cell experiments demonstrated efflux ratio (EfR) of Rh2 ternary solid dispersion was lower than that of pure Rh2. In vivo experiments revealed that the modified formulation substantially improved the absorption of Rh2 in rats. Our research successfully developed an optimal ternary solid dispersion for Rh2 with high solubility, dissolution rate and bioavailability by integrated computational and experimental tools. The combination of Artificial Intelligence (AI) technology and molecular dynamics simulation is a wise way to support the future formulation development.

A zinc phosphate layered biodegradable Zn-0.8Mg-0.2Sr alloy: Characterization and mechanism of hopeite formation

The objective of this study is to comprehensively investigate the formation mechanism of hopeite on a promising biodegradable Zn-0.8Mg-0.2Sr alloy during its self-corrosion process and its subsequent influence on the interaction of the material with cells and bacteria. Notably, the self-corrosion process of Zn-based alloys inherently generates Zn2+ ions, eliminating the necessity for additional zinc compounds in the treatment. The investigation focused on the chemical composition of the applied baths, exposure time, and temperature, in order to analyze the structure, quality, distribution, phase composition, thickness, and roughness of the resulting layers bringing range of key pros and cons for suggested materials. While the thin layers are considered more beneficial in a wide range of applications, the resulting thinnest layer was observed after exposure to the bath containing additives at 50 °C for 24 h, measuring approximately 192 ± 21 pm in thickness. In addition, the layer possessed the most homogeneous distribution under these conditions. Generally, the layers formed in the bath without additives exhibited higher thickness and rougher surfaces compared to those in the bath containing additives. Such results had a direct impact on dissolution rate, cytotoxicity, and antibacterial properties. The highest dissolution rate (40.7 mg·cm−2·day−1) indicating a limited lifetime of the layer was obtained for material processed under the following coating condition: 50 °C, 24 h, and bath without additives. The general presence of surface layers manifested in increased cell viability under direct cytotoxicity test, while smoother surface conditions also supported the antibacterial properties, both making suggested treatments as interesting variations for biodegradable zinc-based materials.

Secondary Enrichment of REE in Weathered Granite, South Bangka, Indonesia

Rare earth elements (REEs) are essential materials for the manufacture of advanced technology. Secondary REE indications were found in alluvial and lateritic tin deposits within Southeast Asia Tin Belt. This study aims at the REE enrichment of weathering profiles underlain by Toboali Pluton of the main range S-type granite of this belt. Granite and weathering samples were collected and analyzed using XRF, ICP-MS/OES, XRD, SEM-EDX, and EPMA. The Chondrite-normalized REE patterns of granite in Toboali showed enrichment in REE with the highest value of 1,126 ppm. The Toboali Pluton is enriched in LREE and depleted in HREE. The enrichment of REE from the upper to lower horizon of weathering profiles was pointed out by the increase in REE values from a range of 156-188 ppm (horizon B) to 196-268 ppm (horizon C) in Toboali, and from a range of 230-330 ppm (horizon B) to 342-450 ppm (horizon C) in Air Gegas. These coincided with the presence of kaolinite with elevated REE and CeO2 in horizon C of weathering profile. Leaching test result proved that kaolinite plays a role in REE enrichment in the weathering profile through ion adsorption mechanisms in the Air Gegas. The weathering process of REE fluoro-carbonate (bastnäsite-(Ce)) and parisite-(Ce) in granite is believed to contribute in enrichment due to its high dissolution rate, which enhances kaolinite adsorption. In contrast, REE phosphates such as monazite-(Ce) and xenotime-(Y), because of their strong resistance and low solubility, are thought to be only slightly soluble, and most of these minerals remain in Toboali weathering products.

Effect of hydrostatic pressure on the anodic dissolution process of X80 steel

Based on the fact that hydrostatic pressure affects chemical potentials of reaction species and the structure evolution of electric double layer (EDL), the authors propose a generalized-BV equation to analyze the anodic dissolution process of X80 steel in deep-sea environment. Combined with the results of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests, the following conclusions can be drawn: hydrostatic pressure can compress the electric double layer non-uniformly. The CHCD (CD: capacitance of diffused layer; CH: capacitance of compact layer) value increases first and then decreases with increasing hydrostatic pressure and reaches its maximum at 15 MPa, which is sure to influence the difference in electrical potential that drives chemical reaction at interface. Ultimately, the anodic dissolution current increases and then decreases with rising hydrostatic pressure at the same anodic polarized potential. Besides, low hydrostatic pressure may contribute to forming a dense corrosion product film and inducing a good inhibiting effect on further dissolution of X80 steel; However, when the hydrostatic pressure exceeds the critical value of 20Mpa, too high anodic dissolution rate along with promoted Cl− adsorption will deteriorate the protection performance of corrosion product film, and exacerbate local corrosion process.

Formulation and evaluation of nifedipine fast dissolving tablets

The current study aims to formulate and evaluate the fast-dissolving tablet. The optimal concentration of Guar gum super disintegrate was found to be 20 mg, with a disintegration time of 27 seconds. This study assessed the disintegration time of tablets containing natural super disintegrant for the Disintegration test at various weight concentrations (6,8,10,12,14,16,18, and 20 mg). As a result, the Nifedipine fast dissolving tablets with Guar gum super disintegrant provide a quick therapeutic effect, a high dissolve rate, and a shorter disintegration time. In this study, the use of a natural (guar gum) super disintegrating agent increases the rate of dissolution as well as length of disintegration of fast-dissolving tablets. In vitro drug release of 96% is demonstrated in 6 minutes with a disintegrating efficiency of 27 seconds for Nifedipine FDTs (guar gum). Consequently, our study has shown that formulations made with a natural super disintegrating agent exhibit shorter disintegration times as well as higher rates of dissolution along with drug release.

Formulation and characterization of ibuprofen solid dispersions using native and modified starches

Background: Ibuprofen is an anti-inflammatory analgesic drug that is weakly water-soluble with a poor bioavailability.Objectives: The aim of this study is to formulate ibuprofen solid dispersions by solvent evaporation method using natural polymers (native cassava and genetically modified cassava (GMS), Cassava nanocrystal and corn starches) as possible hydrophilic carriers at varying weight proportions to optimize ibuprofen solubility and dissolution.Material and Methods: Solvent evaporation method was used to formulate the ibuprofen solid dispersions at different drug polymer ratios. The pure drug and solid dispersions were characterized using Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffractometer (XRD), particle size, and in vitro drug release.Results: Solid dispersions formulated with starch nanocrystals showed the highest solubility. All solid dispersions prepared with drug:polymer ratio 1:2 generally showed highest solubility. According to the FTIR, the chemical structure of ibuprofen remained intact in the amorphous solid dispersion, but the structure changed from crystalline to amorphous, according to the XRD and the DSC also confirmed this. The scanning electron microscopy showed the solid dispersions were more porous than the pure drug. Higher dissolution rate was observed with nanocrystal solid dispersions with T50 (time required for 50% of the medication to be released) between 1.8 and 4.1 minutes.Conclusion: This study has shown that using these natural polymers increased the solubility and dissolution rate of ibuprofen.

Sanctification of African American Couple Relationships and Relational Forgiveness

AbstractObjectiveUsing participant responses from 525 different‐sex married and cohabiting African American couples, we examined the dyadic association between relational sanctification and relational forgiveness.BackgroundReligion has a central role in the lives of many African Americans because it traditionally has been a place of refuge against stressors that disproportionally impact African Americans. However, little is known about how African American couples utilize relational sanctification as a strength.MethodData were collected from African American couples between October 2019 and January 2020 as part of a larger study called the Strong African American Couples Project. Utilizing dyadic panels from Qualtrics, this project specifically targeted African American couples who were cohabiting (n = 233) or married (n = 292) thus, enabling us to analyze a multigroup actor–partner interdependence model.ResultsSignificant actor effects were found between sanctification and individual as well as perceived partner forgiveness in married and cohabiting couple relationships. No significant partner effects were found.ConclusionThese findings highlight the importance of recognizing various aspects of religiosity and spirituality within relationships, especially for African American couples with historically high rates of dissolution and self‐rated religiosity.ImplicationsAs interventionalists work with religious and spiritual African American couples, they need to understand the role that sanctity may have within these partner relationships and the positive impact it can have on relational outcomes.

Corrosion behavior of metallic coatings on titanium bipolar plates of proton exchange membrane water electrolysis

The corrosion resistance, conductivity, and cost of the metallic bipolar plates are the main limitations for the Proton Exchange Membrane Water Electrolysis (PEMWE) commercialization. In the present study, Ta, Nb, and Ti non-precious metallic coatings were deposited by closed-field unbalanced magnetron sputtering to increase the corrosion resistance and conductivity of titanium bipolar plates in PEMWE, respectively. The coating samples suffer from corrosion in a simulated extreme anode operating environment of PEMWE (0.5 M H2SO4 + 5 ppm HF, 80 °C, O2). The surface of the Ti coating forms the micropores due to the high dissolution rate in initial formation stage of the passivation film, resulting in a higher current density (1.41 × 10−6 A cm−2). The hydrolysis reaction of Ta coating causes the adsorption of sulfide ions, thereby affecting the density of the passivation film. Despite the Ta coating exhibiting a favorable current density (4.82 × 10−7 A cm−2), ICR (463.11 mΩ cm2) is lamentably poor. The surface of Nb coating has been completely covered by Nb2O5 and NbO2 in the simulated PEMWE environment. The reoxidation process of NbO2 promotes the rate of passivation film formation and provides excellent conductivity. Therefore, Nb coating exhibits the lowest current density and interfacial contact resistance of 2.23 × 10−8 A cm−2 and 119.78 mΩ cm2, respectively, which is very low compared to the bare titanium bipolar plates.

Optimization of Selective Hydrometallurgical Tantalum Recovery from E-Waste Using Zeolites.

To protect future high-tech metal demand, a selective and efficient recovery method for tantalum from a tantalum-rich e-waste component sample was developed. Ultrasound-assisted digestion of the component sample was optimized, and the highest dissolution rate was achieved using a mixture of 8 mol/L H2SO4 and HF at a temperature of 60 °C. The determined amount of tantalum was as high as 11000 ± 1000 mg/kg, which results in a high potential for recyclable tantalum. The other major elements of this complex e-waste fraction were silicon, iron, aluminum, and tin. Efficient recovery of tantalum from the leachate was performed using the zeolite material ZSM-5. Extremely high selectivity and a recovery rate of over 98% were obtained. In terms of adsorption efficiency, selectivity, and durability of the material, optimal adsorption was obtained using the diluted sample at 0.5 mol/L of H2SO4. The adsorption capacity of ZSM-5 for tantalum was determined to be 10.5 ± 0.6 mg/g, and tantalum was selectively eluted with 1:4 diluted ethanolamine with a yield of 87.2 ± 1.5%.

Properties of Fluorine-Free Steelmaking Flux Prepared Using Red Mud

The basic oxygen steelmaking process is based on the CaO-FeO-SiO2 ternary slag system, characterized by a high melting point and low lime dissolution rate, often becoming one of the key factors limiting the efficiency of the converter. The bulk solid waste red mud, produced by the Bayer alumina process and rich in Fe2O3/Al2O3/Na2O, significantly reduces the melting point of the steelmaking slag system and enhances the efficiency of lime dissolution. This study utilized red mud as the main raw material to prepare a fluoride-free flux. An in situ online observation system was used to measure the melting point of the flux and the dissolution rate of lime in the flux. The results indicate that the melting point of the red mud-based flux is below 1200 °C, and under the same conditions, the lime dissolution rate is 10 to 15 times higher than when this flux is not used. Experiments in a 10 kg induction furnace show that using this flux, the dephosphorization rate under conditions without oxygen blowing is close to 40%, far higher than the rate achieved using CaF2. Under oxygen-blowing conditions, the dephosphorization rate using the red mud-based flux is comparable to that of CaF2, and significantly higher than without any flux, especially under high [C] content conditions. The data show that the red mud-based flux has the potential to be widely used as a fluoride-free flux in the steelmaking process.

Heterogeneous nucleation induced A. pernyi/B. mori silk fibroin coatings on AZ31 biometals with enhanced corrosion resistance, adhesion and biocompatibility

Silk fibroin coatings on biomedical magnesium alloys have garnered significant attention due to their enhanced corrosion resistance and biocompatibility. However, the utilization of wild A. pernyi silk fibroin, known for its RGD sequence that facilitates tissue regeneration, presents a challenge for corrosion-resistant coatings on magnesium alloys due to its weak adhesion and high dissolution rate. In this study, we employed hexafluoroisopropanol as a solvent to blend A. pernyi silk fibroin with B. mori silk fibroin. The resulting blended fibroin coating at a 3:7 mass ratio exhibited a heterogeneous nucleation effect, enhancing β-sheet content (32.3 %) and crystallinity (28.6 %). This improved β-sheet promoted the “labyrinth effect” with an Icorr of 2.15 × 10−6 A cm−2, resulting in significantly improved corrosion resistance, which is two orders of magnitude lower than that of pure magnesium alloy. Meanwhile, the increased content of exposed serine in zigzag β-sheet contributes to a higher adhesion strength. Cell cytotoxicity evaluation confirmed the enhanced cell adhesion and bioactivity. This work provides a facile approach for wild A. pernyi silk fibroin coatings on magnesium alloys with enhanced corrosion resistance, adhesion and biocompatibility.

Magnesium and magnesium alloy dissolution by high intensity focused ultrasound: erosion/cavitation vs. Wave propagation

The dissolution of metals, influenced by mechanical and chemical factors, plays a crucial role in various applications. Ultrasonic irradiation has been explored for its ability to enhance dissolution rates and modify surface characteristics. In this study, we investigate the dissolution of magnesium (Mg) and magnesium alloys under high-intensity focused ultrasound (HIFU) conditions with frequency sweeping (wobbling). Our findings reveal distinct effects of cavitation and acoustic streaming on the dissolution process. For pure magnesium, ultrasonic treatment significantly increases dissolution rates compared to silent conditions. Negative frequency sweeps result in the highest dissolution rates, linked to increased cavitation activity, while positive sweeps reduce dissolution rates but maintain acoustic streaming effects. The removal of surface oxides is accelerated in all sonication conditions. Macro- and micro-roughness patterns on the surface correspond to the wobbling frequency range, with wavelengths matching the average ultrasonic frequency. However, dissolution is not uniform across the sample, and preferential attack occurs at the focal point during negative frequency sweeps. In contrast, magnesium alloys exhibit lower dissolution rates than pure Mg. The alloy's mechanical properties make it less susceptible to cavitation erosion but more sensitive to acoustic streaming-induced dissolution. Grain boundaries are preferentially attacked, revealing differences between ductile pure Mg and the harder, more cavitation-resistant, alloy. This study highlights the complex interplay between cavitation and acoustic streaming in the dissolution of magnesium and its alloys under HIFU conditions, shedding light on the limits and potential applications of this technique, particularly in microstructure analysis.

Dissolution performance enhancement of poorly water-soluble API by crystallization from phase-separated melt

For dissolution enhancement of poorly water-soluble APIs, a novel production method for multi-component solids was proposed by developing the melt crystallization concept into multi-component raw material in which the target API and matrix component were immiscible, and phase separated. The dispersion of the target API in the matrix component is required for dissolution enhancement of the target API. However, the coalescence of the dispersed droplets, which negatively affected API dispersion, occurred in the phase-separated melt. Therefore, the crystallization phenomenon of the matrix component was applied to prevent the coalescence of droplets and keep the API dispersion. The shear force was given to the phase-separated melt to achieve the irreversible phenomenon. As the results of dissolution tests, the multi-phase solid formed using high shear force to the phase-separated melt shows a large amount of API dissolved and an extremely high dissolution rate. Additionally, it was found that the multi-phase solid with a high dissolution rate had the smallest crystal particle size. These results suggest that the dissolution performance of poorly water-soluble API can be enhanced by the synergistic effect of both dispersion of droplets and the precipitation of fine crystals obtained by using high shear force to phase-separated melt.

Chalcopyrite Leaching in Ferric Sulphate: The Effect of Fe3O4-CuFeS2 Galvanic Couple on the Cu Dissolution

Galvanic interactions present alternative strategies to achieve a more efficient Cu dissolution from CuFeS2. The present work studied the interaction between chalcopyrite–magnetite (CuFeS2-Fe3O4) in acidified ferric sulphate Fe2(SO4)3-H2SO4 at a solution pH of 1.8 and a temperature of 25 or 50 °C. The addition of Fe3O4 to CuFeS2 forms a galvanic couple, which positively impacts the dissolution of Cu. The results showed that the presence of Fe3O4 led to high and fast Cu dissolution rates and decreased significantly the activation energy, from 83 to 57 kJ/mol. In addition to that, the solid residues revealed that CuFeS2 dissolution produced intermediate Cu-S-rich phases: CuS, Cu2S and Cu5FeS4, which appeared to envelop CuFeS2, had no observable intermediate phase while in the presence of Fe3O4. The results showed that 94% of Cu could be recovered after 5 h of leaching at 50 °C at a Fe3O4/CuFeS2 ratio of 4:1 and a 460 mV Ag/AgCl solution potential. The findings of this study present an option for efficient Cu dissolution from CuFeS2 in ferric sulphate at atmospheric pressure.