Search Results (718)

A simple and sensitive fluorescence sensing method was developed for ciprofloxacin (CIP) determination based on manganese-doped carbon dots (Mn-CDs). The Mn-CDs were synthesized through a one-step hydrothermal method using anhydrous citric acid and manganese chloride tetrahydrate as precursors. The prepared Mn-CDs exhibited good dispersibility, uniform nanoscale morphology, abundant surface functional groups and favorable fluorescence properties. The incorporation of Mn was designed to introduce coordination-related binding sites for CIP, thereby enhancing the interaction between Mn-CDs and CIP. Under excitation at 330 nm, the Mn-CDs showed a pronounced fluorescence enhancement response toward CIP, enabling their use as fluorescent probes for quantitative detection. Under the optimized conditions, the fluorescence intensity increased linearly with CIP concentration over the range of 20 nM–10 μM, with a detection limit of 1.12 nM. The proposed sensing system exhibited satisfactory selectivity toward CIP over various potentially interfering substances and good storage stability. The practicality of the method was further verified by analysis of pond water samples, affording recoveries of 86–118% with relative standard deviations below 5%. In addition, the method showed acceptable applicability for CIP determination in different pharmaceutical formulations. These results indicate that the Mn-CD-based fluorescent probe provides a convenient, sensitive and promising platform for CIP determination in environmental and pharmaceutical samples. Full article

Surface erosion of loess slopes in arid and semi-arid regions of China remains a critical geotechnical issue, requiring green and low-carbon stabilization techniques. This study investigated the effectiveness of enzyme-induced carbonate precipitation (EICP) for the surface spraying reinforcement of Q3 loess collected from a high-fill engineering site at Yan’an University. Single-factor tests, response surface methodology (RSM), surface strength tests, CT-based three-dimensional pore reconstruction, and scanning electron microscopy (SEM) were conducted to evaluate the effects of cementation solution concentration and spraying dosage. The cementation solution was prepared by mixing analytical-grade urea and anhydrous calcium chloride at a 1:1 molar ratio, and the specimens were compacted to a dry density of 1.4 g/cm³. The results showed that surface strength first increased and then decreased with increasing cementation solution concentration and spraying dosage. Spraying dosage had a more pronounced influence than cementation solution concentration; excessive spraying above 9 L/m² reduced surface strength because of the high water sensitivity of loess. Five replicate tests at the central point were conducted to evaluate experimental error. The optimal parameters were 1.5 mol/L for cementation solution concentration and 9 L/m² for spraying dosage. CT and SEM results showed that CaCO₃ precipitation filled large pores and cemented soil particles, reducing total porosity from 6.7% to approximately 4.0%. These findings indicate that EICP improves loess surface strength mainly through pore filling and particle cementation, providing guidance for the ecological protection of loess slopes. Full article

This investigation focused on isoniazid (INH)—saccharin (SAC) salts. One hydrate and one anhydrous INH-SAC salt form were synthesized and characterized spectroscopically by Raman and infrared spectroscopy. Solvent (methanol, acetone, acetonitrile)-assisted synthesis in the presence of water, or in water, resulted in production of the monohydrated form of the salt (MH: (INH+H)⁺/(SAC–H)⁻.H₂O). The anhydrous form (A: (INH+H)⁺/(SAC–H)⁻) was obtained using the same synthesis method but in the absence of water or, together with the hydrate, in the presence of traces of water. Differential scanning calorimetry studies revealed that the hydrate can be converted into the anhydrous form of the salt upon heating, with the latter melting at a T_m (onset) of 131.7 ± 0.5 °C. Melting was followed by a reaction between isoniazid and saccharin leading to saccharin ring opening and formation of a new covalent hydrazide–amide derivative, via nucleophilic acyl substitution at the saccharin carbonyl. The newly formed adduct, 2-[2-(pyridine-4-carbonyl)hydrazine-1-carbonyl] benzene-1-sulfonamide, melts at T_m (onset) = 204.4 ± 0.5 °C. The crystal structures of the hydrate and of the anhydrous form were determined by single-crystal X-ray diffraction, and the dominant intermolecular interactions in the crystalline INH-SAC salts were evaluated using Hirshfeld surface analysis. To complement the experimental results, density functional theory (DFT) calculations were performed both on relevant isolated structural units and on the two salts, employing fully periodic DFT methods. Full article

Background/Objective: Caffeine has demonstrated ergogenic effects across various doses (2–9 mg·kg⁻¹). However, aerobic responses to caffeine vary substantially, with time-trial performance ranging from ~–3% to +16%. Given that higher doses may increase adverse effects without clear additional benefits, this review examined the effects of low (≤3 mg·kg⁻¹), moderate (4–6 mg·kg⁻¹), and high (>6 mg·kg⁻¹) caffeine doses on time-trial performance. Methods: A systematic review and meta-analysis of randomized, placebo-controlled trials was conducted using PubMed, Embase, and Virtual Health Library databases. Eligible studies included healthy adults (18–59 years) acutely ingesting oral anhydrous caffeine before aerobic time-trial tests, with performance outcomes measured exclusively as time-to-completion variables. Data were pooled using standardized mean differences (SMDs) and 95% confidence intervals under random-effects models, and risk of bias was assessed using the Cochrane Risk of Bias tool. Results: Forty-eight studies (689 participants) met the inclusion criteria. Both low and moderate caffeine doses significantly reduced time-trial completion time relative to placebo. Low doses produced a standardized mean difference of −0.27 (95% CI: −0.44 to −0.11; p = 0.001), whereas moderate doses resulted in an SMD of −0.52 (95% CI: −0.77 to −0.28; p < 0.0001). No studies evaluating high caffeine doses (>6 mg·kg⁻¹) and reporting time-to-completion outcomes met the inclusion criteria. Subgroup analyses demonstrated similar ergogenic effects in both trained and highly trained individuals consuming moderate caffeine doses. Conclusions: This is the first meta-analysis specifically focused on aerobic time-trial performance to suggest that pre-exercise ingestion of low caffeine doses (1.3–3 mg·kg⁻¹) may enhance endurance performance by reducing time-trial completion time. Notably, the use of moderate caffeine doses (4–6 mg·kg⁻¹) appears to produce a more consistent ergogenic effect. Full article

Residual mud cake on the wellbore significantly compromises the cement–formation interfacial cementation quality. However, the research on the weak cementation mechanism of the cementing interface caused by mud cake properties is insufficient. In this paper, laboratory experiments and theoretical analysis were conducted to investigate the influence of mud cake properties on interfacial cementation strength. The results show that the main mechanism of weak cementation of the cement–formation interface caused by mud cake has three aspects: the thickness of mud cake is large, the structure is loose, the strength is low, the bearing capacity is insufficient, and the deformation–compression behavior is small and easily sheared. Based on this, three interfacial strengthening methods, chemical thinning by anhydrous sodium silicate, density enhancement by wollastonite and deformation–compression regulation using sepiolite fibers, were proposed to improve the cementation strength. The addition of anhydrous sodium silicate reduced mud cake thickness by up to 93.5% and increased interfacial cementation strength by 2.43 times. Wollastonite increased mud cake structural stability from 69 to 284 s·mm⁻¹ and improved interfacial cementation strength by up to 2.27 times. Sepiolite fibers increased the deformation–compression coefficient from 1.26 to 1.83, and the maximum interfacial cementation strength was achieved at R ≈ 1.64. In addition, the proposed additives improve the performance of mud cake and have good compatibility with drilling fluid. This study provides a theoretical basis for improving the cementing quality of the cementing interface. Full article

Background: 5-(3′,4′-Dihydroxyphenyl)-γ-valerolactone (DHPV) is a postbiotic gut microbiota-derived flavanol metabolite with reported anti-inflammatory activity. Despite growing interest in its potential dermatological applications, its pharmaceutical properties and suitability for topical delivery have not been systematically investigated. This study aimed to perform the first comprehensive preformulation and formulation-oriented evaluation of DHPV and to develop stable topical ointment formulations suitable for further dermatological research. Methods: The physicochemical properties of DHPV were characterized using powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), quantitative solubility assessment, and excipient compatibility studies. Based on the obtained preformulation data, two anhydrous ointment formulations containing DHPV were developed. The formulations were evaluated for homogeneity, rheological behavior, chemical stability under accelerated storage conditions, and in vitro drug release performance. Results: DHPV was identified as a crystalline compound with heterogeneous particle morphology and limited aqueous solubility. Quantitative solubility studies demonstrated the highest solubility in PEG 300 and glycol-based solvents. Compatibility testing revealed increased impurity formation in hydrophilic environments, whereas lipophilic excipients provided improved chemical stability. Both ointment formulations exhibited acceptable physical characteristics and maintained DHPV stability throughout accelerated storage. However, marked differences in release behavior were observed. The lipid–wax formulation showed significantly higher release rates, lower variability, and more reproducible release profiles than the petrolatum-based reference formulation, indicating more efficient diffusion of DHPV from the semisolid matrix. Conclusions: The physicochemical characteristics of DHPV strongly influence formulation design and performance. Anhydrous lipid-based systems provide a favorable environment for maintaining DHPV stability, while formulation composition significantly affects drug release. The developed lipid–wax formulation represents a promising platform for future skin permeation, pharmacodynamic, and efficacy studies. Full article

Repair mortars containing recycled concrete powder (RCP) and ground granulated blast-furnace slag (GGBFS) are promising low-carbon materials for the rapid repair of concrete structures and pavements. However, their practical use is often limited by slow early hydration, insufficient early strength, and weak bonding with existing concrete substrates. In this study, four early-strength admixtures, namely calcium formate, anhydrous sodium sulfate, calcium acetate, and triethanolamine, were incorporated into a P·I 42.5 cement-based repair mortar containing RCP and a low dosage of GGBFS. Their effects on fluidity, flexural and compressive strength, tensile bond strength, drying shrinkage, and hydration characteristics were investigated. The results showed that the suitable dosages of calcium formate, anhydrous sodium sulfate, calcium acetate, and triethanolamine were 1.5%, 1.0%, 0.8%, and 0.05% by mass of total cementitious materials, respectively. Among the four admixtures, calcium formate provided the best balance among strength enhancement, bond performance, workability retention, and dosage tolerance. Compared with the control group, the 3 d and 28 d flexural strengths of the 1.5% calcium formate group increased by 37.0% and 20.3%, respectively. Anhydrous sodium sulfate gave the highest tensile bond strength, with the 14 d value increasing by 33.15% to 1.052 MPa, but its effective dosage range was relatively narrow. Calcium acetate was more effective in reducing drying shrinkage, with a 28 d shrinkage value of 695.14 × 10⁻⁶. SEM and XRD results suggested that the admixtures mainly accelerated early hydration, while no new major crystalline phases were detected. Excessive dosages caused strength loss, bond deterioration, or increased drying shrinkage. These findings are applicable to the specific RCP–GGBFS repair mortar formulation and dosage ranges investigated here. They provide a practical basis for selecting early-strength admixtures for RCP-containing repair mortars used in concrete structure and pavement repair. Full article

Phosphoric acid-doped polybenzimidazole membranes are a leading fluorine-free electrolyte platform for high-temperature proton exchange membrane fuel cells, enabling proton transport under anhydrous conditions. However, recent evidence shows that conductivity, mechanical stability, and acid retention are intrinsically coupled, preventing independent optimization of these properties. This review establishes a unified framework in which membrane performance is governed by a multidimensional design space defined by acid doping level, activation energy (E_a), hydrogen-bond network topology, and mechanical confinement. Conductivity is shown to scale with both carrier density and hopping energetics, while mechanical stability decays with increasing ADL due to acid-induced plasticization, described through a semi-empirical relationship. Analysis across molecular architectures, including molecular weight control, crosslinking, backbone modification, topological design, and free-volume engineering, demonstrates that performance emerges from a balance between transport efficiency and structural stability. Device-level benchmarking further reveals that similar conductivity values can correspond to orders-of-magnitude differences in voltage decay rate, confirming that durability is governed primarily by mechanical confinement and acid mobility rather than σ alone. A multivariate stability corridor is identified, within which phosphoric acid-doped polybenzimidazole membranes achieve σ ≈ 0.14–0.20 S·cm⁻¹ while maintaining low degradation rates under realistic high temperature proton exchange membrane conditions. Based on this framework, quantitative design rules are derived linking acid doping level, activation, topology, and mechanical properties. This work shifts membrane design from conductivity-driven optimization toward predictive structure–property–durability engineering, providing a basis for the development of next-generation HT-PEM fuel cells with sustained long-term performance. Full article

Energetic materials face dual challenges of enhancing detonation performance and replacing toxic lead-based formulations. Triazole-based energetic potassium salts typically struggle to achieve simultaneous high-density and excellent detonation properties. Herein, a novel gem-dinitro-functionalized 1,2,3-triazole energetic salt, tripotassium 4,5-bis(gem-dinitromethyl)-2H-1,2,3-triazolate (3K₃BNOT·4H₂O), was rationally designed and synthesized via a six-step mild route using diaminomaleonitrile as the starting material. The structure was fully characterized by IR, NMR, elemental analysis, and single-crystal X-ray diffraction (SC-XRD). 3K₃BNOT·4H₂O crystallizes in the triclinic system (space group P-1) and forms a three-dimensional K-O/K-N ionic coordination network, delivering an ultra-high anhydrous crystal density of 2.077 g·cm⁻³ at 193K. It exhibits a peak decomposition temperature of 183.8 °C (10 °C·min⁻¹), impact sensitivity of 5 J, and friction sensitivity of 60 N (standard BAM methods). The calculated detonation velocity and pressure reach 8836 m·s⁻¹ and 28.6 GPa, respectively, outperforming the classical explosive RDX. This work provides a structural analysis of triazole-based energetic potassium salt hydrates, and 3K₃BNOT·4H₂O shows structural potential as a high-energy energetic material; its initiating performance needs further experimental verification. Full article

Caffeine is the world’s most widely consumed psychoactive compound, yet it presents a growing challenge in forensic toxicology due to the proliferation of highly concentrated energy drinks, dietary supplements, and pure anhydrous powders. This review provides a comprehensive evaluation of the diverse sources of caffeine, complex pharmacokinetics, and critical medico-legal implications. While moderate consumption is socially accepted, fatal intoxications are increasingly reported. The toxic effects of caffeine primarily manifest through a number of mechanisms which range from mild effects to sudden cardiac death. Forensic interpretation is inherently complex due to significant inter-individual variability. Analytical determination relies on advanced techniques, with LC-MS/MS serving as the preferred platform for its high sensitivity and ability to quantify primary metabolites like paraxanthine. A critical challenge in postmortem cases is postmortem redistribution, where central blood levels may be artifactually elevated compared to peripheral sites, necessitating more complex matrix analysis. To standardize the evaluation of the role of caffeine in causing death, a proposed Toxicological Significance Score (TSS) framework is discussed to enhance the transparency and defensibility of expert testimony. Ultimately, accurately determining the manner of death requires a nuanced, case-by-case assessment that integrates toxicological findings with circumstantial evidence and individual medical histories. Full article

This study reports the intermediate-temperature proton exchange membrane (IT-PEM) based on an oligomeric vinyl sulfonic acid (OVS)-infiltrated crosslinked porous polybenzimidazole (cp-PBI) framework. The cp-PBI membrane, fabricated via ZIF-8-templated porosity and covalent crosslinking, provides a mechanically robust and chemically stable host matrix that enables high uptake and uniform distribution of OVS throughout the membrane bulk. In situ oligomerization of vinyl sulfonic acid yields a wax-like OVS ionomer with high proton density and reduced mobility, effectively suppressing ionomer leaching while maintaining efficient proton transport under anhydrous conditions. The resulting membrane exhibits high proton conductivity of 8.4 × 10⁻³ S cm⁻¹ at room temperature and 2.6 × 10⁻² S cm⁻¹ at 110 °C without any external humidification. Compared to dense PBI and conventional phosphoric acid (PA)-doped systems, the composite membrane demonstrates significantly enhanced ionomer retention, with only 2.3 wt% loss under compressive conditions and improved stability under humid environments. These results highlight the synergistic effect of a porous crosslinked host and viscous oligomeric ionomer, providing a promising strategy for designing stable, high-performance IT-PEMs. Full article

Antioxidative substances constitute the important barrier maintaining the oxidative stability of edible oils against lipid degradation and the formation of harmful aldehydes and ketones. In this study, an oil-compatible non-aqueous electrochemical method was developed to characterize the oxidation behaviour of antioxidative substances in an oil-based solution, in which linear sweep voltammetry (LSV) was employed to investigate the effects of oxidation potential and current on antioxidative capabilities of eleven antioxidative substances, including both natural and synthetic compounds, in a mixed anhydrous model oil system. Among them, eight antioxidative substances exhibited characteristic oxidation peaks in the mixed solution containing 0.1 mol/L Lithium perchlorate, 40% (v/v) C8 medium-chain triglyceride, 35% anhydrous ethanol and 25% 1,2-dichloroethane, with the first oxidation peak potentials (vs. Ag/AgCl) increasing in the order: TBHQ (100–800 mg/kg, (−247)–(−119) mV), PG (100–800 mg/kg, 74–248 mV), α-tocopherol (100–800 mg/kg, 95–142 mV), δ-tocopherol (100–850 mg/kg, 190–241 mV), BHT (100–800 mg/kg, 238–256 mV), β-carotene (100–870 mg/kg, 562–624 mV), lutein (100–850 mg/kg, 631–680 mV) and ergosterol (100–850 mg/kg, 1240–1300 mV), while their peak potentials were negatively correlated with the DPPH and Galvinoxyl radical-scavenging capacity, suggesting that, under the present oil-based conditions, lower oxidation peak potentials tended to be associated with stronger radical-scavenging capacity. The concentration–current relationships were compound-dependent and followed linear, cubic, or logarithmic patterns. And the oxidation of phenolic antioxidative substances shifted from a low-potential to a higher-potential process under acidic conditions. Overall, this study reveals the electrochemical oxidation properties of antioxidative substances in the oil-based solution, and provides the electrochemical characteristic method of the antioxidant capacities of antioxidative substances and application guidance for antioxidative substances screening in oil. Full article

A one-pot strategy was developed for preparing a chitosan/Mg–Fe layered double hydroxide (LDH) composite by alkaline coprecipitation from an acidic chitosan solution containing Mg(II) and Fe(III) precursors, avoiding separate LDH synthesis and subsequent incorporation into chitosan. X-ray diffraction confirmed LDH formation within the chitosan matrix, and ICP analysis indicated an LDH-equivalent content of approximately 4.1 wt.% on an anhydrous basis. The composite exhibited enhanced chromate adsorption compared with both starting components. The experimental plateau adsorption capacity reached 137.4 mg/g, exceeding those of chitosan (92.2 mg/g) and Mg–Fe LDH (53.5 mg/g). Nonlinear isotherm fitting showed that Mg–Fe LDH was better described by the Freundlich model, whereas chitosan and the composite were better described by the Langmuir model. The kinetic behavior followed the pseudo-second-order equation, while Weber–Morris analysis indicated multistep uptake involving surface interaction and diffusion-related processes. In simulated groundwater containing chloride, bicarbonate, and sulfate, the composite removed 82% of Cr(VI) at 1.0 g/L. It also retained complete chromate uptake over five sorption/desorption cycles, although desorption efficiency decreased from 97.3% to 90.3%. A limitation of this study is that performance was evaluated mainly in batch systems and simplified simulated groundwater; validation with real contaminated waters and dynamic flow conditions is still required. Full article

Noble metal nanostructures based on localized surface plasmon resonance (LSPR) can induce metal-enhanced fluorescence (MEF) and surface-enhanced Raman scattering (SERS), significantly improving trace detection sensitivity for biomedical and chemical analysis. While self-assembly of noble metal nanoparticles offers simplicity and low equipment dependence, achieving large-area, uniform, and controllable nanostructures remains challenging. In this study, angle-dependent dip coating (ADDC) technology was employed to achieve efficient, controllable self-assembly of silver nanoparticles (AgNPs) on glass slides, establishing a fabrication process for MEF/SERS dual-functional substrates. A stable AgNPs-anhydrous ethanol suspension was prepared and extracted from an inclined substrate reservoir using a microfluidic syringe pump, enabling large-area uniform nanostructure assembly. Systematic investigation revealed that substrate inclination angle provides better morphology and fluorescence enhancement control than withdrawal flow rate. The silver nanostructured surface fabricated under a withdrawal flow rate of 16 mL/h and a substrate inclination angle of 30° exhibited a Cy3 detection limit as low as ${10}^{-1}$ nM, with an enhancement factor ranging from 19.14 to 28.66, as well as an R6G SERS detection limit of ${10}^{-10}$ M with an enhancement factor of 4.07 × ${10}^8$. This study confirms that ADDC technology enables simple, efficient, large-area uniform AgNPs self-assembly for superior dual-function enhancement substrates, offering a cost-effective and efficient strategy for highly sensitive trace detection. Full article

Purpose: The aim of this study was to investigate the safety and efficacy, as well as relief of symptoms after regular use, of 0.5% lidocaine hydrochloride solution in anhydrous glycerol (Auridol) in the form of ear drops, in patients with symptoms of otitis externa (OE) in a real-world setting. Methods: This real-world pre–post study included 64 subjects aged 1 to 69 years with symptoms as follow: swelling, pain due to regular exposure to water or caused by frequent use of detergents, pain due to prolonged wearing of earphones, or earwax clogging the external auditory canal. In each subject, following an otoscopic examination and interview given by an ENT, the Auridol treatment was initiated. The product was administered as two drops into the affected ear up to three times daily in patients with symptoms of OE. During each visit, physical and functional symptom were evaluated. In addition, the efficacy of using the product was assessment using a VAS scale. At the end of the study, subjects rated the product according to a Likert scale. Results: A statistically significant reduction in perceived pain was observed at t = 30′ as well as t = 3 days after application. For physical symptoms assessed by an ENT, a statistically significant difference was observed between consecutive scores for two of the assessed parameters (redness and swelling.) The product was rated very highly by the subjects. Conclusions: The results suggest that a combination of anhydrous glycerol and 0.5% of lidocaine in the form of ear drops has a positive effect in the treatment of symptoms of OE. Full article