Search Results (126)

Background: Furosemide is a loop diuretic used extensively to treat adult and pediatric patients. In some hospitals, furosemide oral liquids are not available in stock, thus necessitating the extemporaneous preparation of the drug. This study evaluates the stability of on-the-spot formulations of furosemide oral suspensions from crushed tablets evaluated in various vehicles: Dextrose 50%, Dextrose 70%, Ora-Sweet, and Ora-Plus over 60 days. This examination was prompted by the frequent shortage of certain excipients in the hospital, leading to the need to switch to Dextrose 50% or Dextrose 70% when Ora-Sweet and Ora-Plus are out of stock. Methods: The extemporaneous furosemide oral suspensions were prepared following the same compounding method used in the pharmacy. The suspensions were maintained at 4 °C in the refrigerator and assessed immediately and later, on days 7, 14, 30, and 60. The assessed parameters included visual appearance, redispersion time, sedimentation volume, and pH levels for stability analysis. We also examined the drug content, dissolution of the suspension, and microbiological stability. Results: Initial examinations indicated that Dextrose 50% and Ora-Plus maintained pH levels and stable appearances, while significant changes, mainly in appearance and redispersion time, indicated the instability of Dextrose 70%. Ora-Sweet showed fluctuations but stabilized by day 30. Dissolution studies demonstrated that Ora-Plus had dissolution characteristics superior to the other formulations, while Dextrose 50% showed declining dissolution percentages over time. Overall, the Ora-Plus vehicle showed superior stability (60 days), followed by Ora-Sweet (30 days), while Dextrose 70% and Dextrose 50% showed shorter stability durations of 14 and 7 days, respectively. The microbiological test results showed no microbial growth. Conclusions: This study demonstrates that the vehicle used in extemporaneous furosemide suspensions critically affects their stability and performance. Ora-Plus emerged as the most suitable vehicle, maintaining physical, chemical, and microbiological stability over 60 days, with consistent pH, redispersion, and dissolution behavior. Ora-Sweet showed intermediate stability (30 days), while Dextrose 50% and 70% exhibited early instability—7 and 14 days, respectively—marked by sedimentation, poor redispersibility, and declining drug release. These findings underscore the importance of vehicle selection and regular stability monitoring in compounded formulations to ensure therapeutic reliability and patient safety. Full article

Background/Objectives: The growing interest in personalized medicine has accelerated the exploration of three-dimensional (3D) printing technologies in pharmaceutical applications. This study investigates the potential of selective laser sintering (SLS) as a flexible, small-scale manufacturing method for atomoxetine tablets tailored for individualized therapy, comparing it with conventional direct compression. Methods: Atomoxetine tablets were produced using SLS 3D printing with varying laser scanning speeds and compared to tablets made via a compaction simulator. Formulations were based on hydroxypropyl methylcellulose (HPMC) as the primary matrix former. The physical properties, drug content, disintegration time, and dissolution profiles were evaluated. The structural and chemical integrity were assessed using SEM, FTIR, DSC, and XRPD. Results: The SLS tablets exhibited comparable mechanical properties and drug content to those made by compaction. Lower laser speeds produced harder tablets with slower disintegration, while higher speeds yielded more porous tablets with ultra-rapid drug release (>85% in 15 min). All tablets met the European Pharmacopoeia dissolution criteria. No significant drug–excipient interactions or changes in crystallinity were detected. Conclusions: SLS printing is a viable alternative to traditional tablet manufacturing, offering control over drug release profiles through parameter adjustment. The technique supports the development of high-quality, patient-specific dosage forms and shows promise for broader implementation in personalized pharmaceutical therapy. Full article

When iron sulfides are used as aggregate in concrete production, it easily oxidizes to form harmful substances such as sulfates. This results in acid corrosion and internal sulfate attack (ISA), significantly reducing concrete durability. To date, the quantification methods for iron sulfides in aggregates remain inaccurate, often neglecting pyrrhotite (a type of iron sulfide). No standardized methods or threshold values for the sulfide content in aggregates have been established, nor have technical guidelines for the application of sulfide-containing aggregates, limiting their use. This study proposes an on-site quantification procedure for determining the pyrite and pyrrhotite content in tailings using a selective chemical dissolution process. An orthogonal experiment was designed to determine the optimal dissolution conditions by considering four factors: particle size, reaction temperature, acid concentration, and reaction time. The pyrrhotite quantification method showed a relative standard deviation (RSD) of 3.60% (<5%) and a mean relative error of 3.19% (<5%), while the pyrite quantification method showed an RSD of 3.11% (<5%) with a mean relative error of 4.70% (<5%). The results were further optimized under engineering conditions to reduce costs and enable on-site quantification without relying on complex precision instruments. The quantitative results of pyrite in mineral samples were verified by the XRD internal standard method, and the error was less than 0.6%. This approach ensures the effective monitoring and management of sulfide content in concrete aggregates, promoting the practical application of sulfur-bearing aggregates. Full article

Heap leaching of copper is faced with a complex set of challenges, including mineral heterogeneity, the formation of passivating species, and the need to regulate critical variables such as pH, redox potential (Eh), oxidant concentration, and irrigation rate. If these factors are not properly managed, copper recovery is reduced, and significant environmental impacts may be generated, highlighting the urgency for systematic and sustainable approaches. To address this challenge, a systematic literature review (SLR) was conducted, screening 2344 documents and selecting 106 primary sources to analyze operational drivers and environmental considerations. Statistical methodologies (factorial designs, response surface methodology), multiscale modeling, and laboratory column tests were used to validate key variables, including pH (1.5–2.0), Eh (600–$750 \mathrm{mV}$), temperature (25–55 °C), irrigation rate (5–$15 \mathrm{L}/\left(\mathrm{h}·{\mathrm{m}}^2\right)$), acid concentration (0.5–$2.0 \mathrm{M}$), and emerging “green” reagents (e.g., glycine, organic surfactants). Precise control of these factors was found to reduce passivation, minimize fine-particle migration, and improve copper extraction up to 90%. The incorporation of oxidizing agents (e.g., Fe³⁺, H₂O₂) further accelerated mineral dissolution while preventing unwanted precipitates. In parallel, bioleaching strategies maintained high recoveries with lower chemical demand. Reviews of pilot studies confirmed the scalability of these optimized conditions, emphasizing both sustainability and cost-effectiveness. Full article

Vehicle identification number (VIN) reappearance technology is an important means of vehicle traceability in various criminal cases. However, with the advancement of metallurgical techniques, the corrosion resistance of metal becomes stronger, and the traditional chemical etching reappearance method gradually fails. In order to break through the dilemma of traditional methods, this study establishes an electrochemical corrosion system by introducing the corrosion inhibitor hexamethylenetetramine (HMTA) to precisely regulate the electrochemical dissolution kinetics. Material characterization and electrochemical measurements demonstrated that the selective adsorption of HMTA significantly enhances the potential difference between plastically deformed regions and the normal metal substrate (ΔE_max = 6 mV). By effectively suppressing the corrosion rate in non-target areas, HMTA promotes selective anodic oxidation reactions in the vehicle identification number character regions due to their distinct microstructural characteristics, thereby substantially improving the contrast of the reappeared VIN markings. Density functional theory calculations and molecular dynamics simulations further reveal the formation of a dense adsorption layer, which is a key factor in improving the reproducibility of the results. The experimental results demonstrate that under conditions of 6 V applied voltage, with 0.5 M hydrochloric acid and 0.02–0.03 M HMTA in the electrolyte, efficient VIN reappearance could be achieved within 3–4 min on filed-down surfaces. Full article

Cotton fiber, renewable natural cellulose, make up the largest portion of textile waste. The ionic liquid method has been successfully employed to regenerate waste colored cotton fabric in this study, offering a comprehensive approach to the recycling of waste cotton. The chemical recovery process for reclaimed cellulose materials is crucial for high-value recycling of waste cotton fabrics. In this study, waste and new, colored and white cotton fabrics were used as experimental subjects. The breaking strength, degree of polymerization, iodine adsorption equilibrium value, and crystallinity between old and new fabrics were investigated. Ionic liquid 1-allyl-3-methylimidazole chloride ([AMIM]Cl) and zinc chloride (ZnCl₂) were selected to dissolve decolorized waste cotton fabric. Optimal conditions for dissolving the fabric using [AMIM]Cl were investigated. The best dissolution conditions identified were DMSO at a ratio of 1:1 with a dissolution temperature of 110 °C over a duration of 120 min. Additionally, the optimal film formation parameters included a solution concentration of 6%, solidification time of 3 min, and solidification bath temperature of 0 °C. Regenerated cellulose films from both the ionic liquid system (A-film) and zinc chloride system (Z-film) were prepared. The characteristics of the film produced using the most advanced technology were systematically investigated and evaluated. The results of this study provide a crucial theoretical foundation for the recovery and regeneration of waste cotton fabrics. Full article

In the present work, the application of lignin (LIG) as a bioactive additive for the preparation of drug-loaded tablets by direct compression has been studied, and its influence on the release of chlorzoxazone (CLZ) from the hydrophilic matrices has been followed. In hydrophilic matrices, the excipients Kollidon^® SR (KOL) and chitosan (CHT) have been used in various amounts and tested in the preparation of 500 mg tablets. They were used as matrix-forming agents, and their influence on the flow and the compressibility properties as well as their effect on the pharmaco-chemical characteristics of the matrix tablets have been studied. Based on the initial evaluation of the pharmaco-technical analysis, pharmaco-chemical characteristics, and in vitro release profile, three matrix tablet formulations (FLa, FLb, and FLc) were selected and further tested. They were evaluated through Fourier-transform infrared spectrometry (FTIR), X-ray diffraction (XRD), thermogravimetry (TG), differential scanning calorimetry (DSC), and in vitro dissolution tests. The three formulations were comparatively studied regarding the release kinetics of active substances using in vitro release testing. The in vitro kinetic study reveals a complex release mechanism occurring in two steps of drug release. The first one is a burst effect that occurs within the first 0–2 h, involving a rapid release of the majority of the drug in a short time, followed by the second step as a prolonged release of the drug, which is relatively constant with a fixed rate over the next 2–36 h. Two factors have been calculated to assess the release profile of chlorzoxazone: f1—the similarity factor and f2—the difference factor together with the correlation coefficient R². Comparing their values, the three optimal formulations have been selected, containing 55 mg LIG (FLa), 60 mg LIG (FLb), or 65 mg LIG (FLc), confirming that LIG next to KOL and CHT influenced the release characteristics of the matrix tablets. Due to the presence of lignin in the matrix of the three formulations, FLa, FLb, and FLc tablets with CLZ, the antioxidant activity has improved. The antioxidant activity of FLc was found to be 21.36% ± 1.06 greater than that of FLa and FLb. The tablets FLa, FLb, and FLc also presented higher antimicrobial activity against Staphylococcus aureus, Escherichia coli, Candida albicans, and colistin-resistant Klebsiella spp. The higher the concentration of LIG in the matrix (FLc), the higher the antimicrobial activity. By using LIG, the drug dose could be decreased. It can be concluded that lignin can be used as a multifunctional pharmaceutical bioactive additive/excipient for tablets. Its interesting properties have been proven, and its use as a pharmaceutical active additive should be exploited for different applications. Full article

Carbon dioxide (CO₂) storage in sandstones is vital for enhancing oil/gas recovery and reducing CO₂ emissions. The introduction of CO₂ into sandstone reservoirs leads to chemical reactions between CO₂ and minerals present in sandstone, which changes the pore structure of the sandstone reservoir. Herein, tight sandstone samples from the Coal-Measure Strata of the Shanxi Formation in the Huxiang area, Henan Province, were selected for simulation in this experimental study under supercritical CO₂ (ScCO₂)–H₂O treatment in reservoir conditions. Further, mercury intrusion porosimetry and low-pressure nitrogen adsorption/desorption methods were used to analyze the evolution of the pore structures of tight sandstones, and the mechanism of pore structure evolution was discussed. The results show that pore volumes and specific surface areas in the micropores and transitional pores decreased after the ScCO₂–H₂O treatment, while those in the mesopores and macropores increased. In the micropores and transitional pores, some of the pores changed from open pores and ink-bottle-shaped pores to semi-closed pores after the ScCO₂–H₂O treatment, and the pore morphology became narrower, which might have deteriorated the pore connectivity. A pore structure evolution model of ScCO₂–H₂O-treated tight sandstones was proposed. The evolution of pore structure is a result of the synergistic effect of pore enlargement caused by mineral dissolution and secondary mineral precipitation, which together play a controlling role in pore structure evolution. This study is conducive to understanding the pore structure evolution under ScCO₂–H₂O treatment and implementing CO₂ storage and enhancing oil/gas recovery in sandstone reservoirs. Full article

During the grinding process, magnesite (MgCO₃) and calcareous gangue minerals, such as dolomite (MgCa(CO₃)₂), are prone to surface dissolution. The dissolved metal ions adsorb onto the mineral surfaces, causing the surface properties of both minerals to converge, which complicates flotation separation. This study investigates the use of ethylene glycol tetra-acetic acid (EGTA) to optimize the grinding–flotation system for the recovery of magnesite. The mechanisms underlying EGTA’s effects on the minerals were examined through various characterization techniques, including contact angle measurements, zeta potential analysis, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma optical emission spectrometry (ICP-OES). Single-mineral flotation tests revealed that EGTA addition during grinding enhanced the separation between magnesite and dolomite in flotation. An artificial mixed-ore flotation yielded a concentrate with 46.47% MgO grade and 92.21% MgO recovery. Mechanistic studies indicated that EGTA selectively adsorbed onto Ca sites on the surface of dolomite, increasing its hydrophilicity. Additionally, EGTA effectively chelated Ca²⁺ in the slurry, improving the chemical environment. Therefore, EGTA demonstrated significant potential for improving the flotation of magnesite. Full article

The source of sulfate in the groundwater of karst springs in the northern Taihang Mountains remains unclear due to the influence of multiple factors. To investigate this, 33 sampling points were selected in August 2022 across the exposed, covered, and buried areas of the spring basin, and water samples were collected. Hydrochemistry and sulfur–oxygen dual isotope methods were employed to examine the distribution characteristics of sulfate, δ¹⁸O_SO4, and δ³⁴S_SO4. Based on the distinct characteristics of sulfur isotopes from different sources, the sources of sulfate in various environments were qualitatively analyzed. Additionally, the contribution rates of each source were quantitatively determined using a Bayesian stable isotope mixing model. The results showed that the sulfate content in karst groundwater ranged from 16.68 to 156.84 mg/L, with an average of 62.22 mg/L, and indicated an increasing trend from exposed to covered to buried areas. The δ³⁴S_SO4 values in karst groundwater ranged from 3.1‰ to 13.5‰, with an average of 6.49‰, while the δ¹⁸O_SO4 values ranged from 2.9‰ to 10.3‰, with an average of 5.49‰. The δ³⁴S_SO4 values showed a general increasing trend across the exposed, covered, and buried areas, whereas the δ¹⁸O_SO4 values remained relatively stable across these areas. The analysis revealed that the primary sulfate sources in the exposed area were atmospheric precipitation, soil sulfate, chemical fertilizer, and sewage, contributing 19.6%, 63.5%, 9.4%, and 7.5%, respectively. In the covered area, the main sources were atmospheric precipitation, sulfide oxidation, soil sulfate, and gypsum dissolution, with contributions of 16.5%, 58.7%, 15.9%, and 8.9%, respectively. In the buried area, the sulfate primary originated from atmospheric precipitation, sulfide oxidation, and gypsum dissolution, contributing 11.6%, 78.5%, and 9.9%, respectively. This study provides critical insights into the sulfate sources in different environments, enhancing the understanding of groundwater sulfate pollution in the study area. These findings provide a scientific foundation for managing groundwater pollutants and resources in the karst regions of northern China. Full article

This study investigates the fabrication of nanostructured chromium thin films via selective dissolution of PVD-deposited Cu–Cr thin films. The effects of the deposition parameters on the structural, chemical, and morphological properties of the films are systematically analyzed. Starting from a thin film composed of 50 wt.% chromium and 50 wt.% copper, deposited onto a substrate pre-heated to 300 °C, we demonstrate that the following dealloying process carried out in a diluted nitric acid solution yields nanostructured chromium films with high porosity, large surface area, enhanced wettability and neglectable copper content. These findings underline the critical influence of the deposition temperature and alloy composition on achieving optimal film properties. Full article

The optimization and evaluation of 3D-printed polylactic acid (PLA) materials for reinforcing concrete elements present a promising avenue for advancing sustainable construction methods. This study addresses the challenges associated with PLA’s dual nature—biodegradable yet mechanically limited for long-term applications—while leveraging its potential to enhance concrete reinforcement. The research identifies gaps in understanding PLA’s mechanical and chemical behavior in alkaline environments, particularly its interactions with concrete matrices. To bridge this gap, four distinct PLA variants (high-impact PLA, engineering PLA, electrical ESD PLA, and gypsum PLA) and ABS (acrylonitrile butadiene styrene) were subjected to dissolution tests in NaOH solutions (pH 12 and 12.55) and mechanical evaluation under three-point bending using digital image correlation (DIC) technology. Test specimens were prepared using optimized 3D printing strategies to ensure structural consistency and were embedded in concrete beams to analyze their reinforcement potential. Force–displacement data and GOM ARAMIS measurements revealed significant differences in mechanical responses, with peak loads ranging from 0.812 kN (high-impact PLA) to 1.021 kN (electrical ESD PLA). Notably, electrical ESD PLA exhibited post-failure load-bearing capacity, highlighting its reinforcement capability. Chemical dissolution tests revealed material-specific degradation patterns, with high-impact and Gypsum PLA showing accelerated surface changes and precipitation phenomena. Observations indicated white crystalline precipitates, likely lime (calcium hydroxide—Ca(OH)₂), residue from the dissolution tests (sodium hydroxide—NaOH), or material-derived residues formed on and near PLA elements, suggesting potential chemical interactions. These findings underline the critical role of material selection and optimization in achieving effective PLA–concrete integration. While PLA’s environmental sustainability aligns with industry goals, its structural reliability under long-term exposure remains a challenge. The study concludes that electrical ESD PLA demonstrates the highest potential for application in reinforced concrete, provided its chemical stability is managed, as its peak value (1.021 kN) showed 25.7% higher load-bearing capacity than high-impact PLA (0.812 kN) and did not lose any of its structural stability in the dissolution tests. This work advances the understanding of PLA as a sustainable alternative in construction, offering insights for future material innovations and applications. Full article

As new technologies are developed, the demand for rare earth elements (REEs) has increased, despite limited awareness of their significant impact on people and the environment. In this study, waste fly ash was used as a precursor to synthesize inorganic aluminosilicate polymers by adding an activator to the alumina and silica compounds of the ash. Due to their structure and adsorption potential, their application for the removal of selected REEs (Gd³⁺, Y³⁺, and Sc³⁺) from water has been investigated. A decrease in the intensity of the quartz peak at 2θ of 26.6° in the XRD spectrum and the disappearance of the albite and mullite peaks due to dissolution during alkaline activation in both modified samples were observed. The appearance of a peaks at 2θ of 29.3° and 39.3° corresponding to calcite in the modified sample indicates the presence of wood ash. A shifting of the band in the DRIFT spectrum to 1030 cm⁻¹ on the spectra of modified samples corresponds to the vibrations of Al-O and Si-O bonds and the formation of a polymeric network structure (Si-O-Si or Si-O-Al). According to pH_PZC values, thermodynamic and kinetic parameters, and chemical composition, the presumed mechanism of REE adsorption is chemisorption and ion exchange. The highest adsorption efficiencies (up to 95%) for all examined REEs in both single and mixed REE solutions were obtained from an alkali-activated mixture of fly ash and wood ash. The results of this research are significant for expanding knowledge about the removal of REEs from the environment, the reduction of waste ash by their modification, and their potential subsequent use in construction as additives. Full article

Background/Objectives: Omeprazole undergoes degradation in acidic conditions, which makes it unstable in low pHs found in the gastric environment. The vast majority of already marketed omeprazole formulations use enteric polymer coatings to protect the drug from exposure to acidic pH in the stomach, allowing for drug release in the small intestine where the pH is higher. This study aimed to explore the technical aspects of using stomach acid neutralizers as an alternative to polymeric coatings for omeprazole. Methods: After evaluating various neutralizers, magnesium oxide and sodium bicarbonate were chosen to be incorporated into capsules containing omeprazole, which then underwent in vitro dissolution testing to assess their ability to maintain optimal pH levels and ensure appropriate dissolution kinetics. Hygroscopicity and chemical stability of the selected formulation were tested to prove pharmaceutical quality of the product. An in vivo pharmacokinetic study was conducted to demonstrate the efficacy of the omeprazole–sodium bicarbonate formulation in providing faster absorption in humans. Results: Sodium bicarbonate was selected as the most suitable antacid for ensuring omeprazole stabilization. Its quantity was optimized to effectively neutralize stomach acid, facilitating the rapid release and absorption of omeprazole. In vitro studies demonstrated the ability of the formulation to neutralize gastric acid within five minutes. In vivo studies indicated that maximum concentrations of omeprazole were achieved within half an hour. The product met the requirements of pharmaceutical quality. Conclusions: An easily manufacturable, fast-absorbing oral formulation was developed as an alternative to enteric-coated omeprazole. Full article

Apigenin (APG), a bioactive flavonoid with promising therapeutic potential, suffers from poor water solubility, which limits its bioavailability. To address this, solid dispersions of APG were prepared using ball milling with sodium alginate (SA), Pluronic^® F-68 (PLU68), Pluronic^® F-127 (PLU127), PVP K30, and PVP VA64 as polymeric excipients. These dispersions were screened for apparent solubility in water and buffers with pH 1.2, 5.5, and 6.8. Based on improved solubility after 60 min, APG–PLU68 and APG–PLU127 dispersions were selected for further study. DSC and FT-IR analysis confirmed molecular interactions between APG and the polymer matrices, contributing to enhanced solubility and dissolution rates. Dissolution rate studies showed that APG–PLU127 achieved 100% solubility at pH 6.8, suggesting its potential use in environments such as the small intestine. Additionally, APG–PLU127 exhibited 84.3% solubility at pH 1.2, indicating potential for solid oral dosage forms, where APG could be absorbed in the acidic conditions of the stomach. The stability study confirmed that storage for one year under ambient conditions does not cause chemical degradation but affects the physical state and solubility of the dispersion. Antioxidant activity was assessed using the ABTS assay. Freshly obtained APG–PLU127 showed 68.1% ± 1.94% activity, whereas APG–PLU127 stored for one year under ambient conditions exhibited 66.2% ± 1.62% (significant difference, p < 0.05). The difference was related to a slight decrease in the solubility of APG in the solid dispersion (T0 = 252 ± 1 μg∙mL⁻¹, T1 = 246 ± 1 μg∙mL⁻¹). The findings demonstrate the superior performance of PLU127 as a carrier for enhancing the solubility, release, and antioxidant activity of APG. Full article