Search Results (367)

Metal–organic frameworks (MOFs) have characteristics such as a large specific surface area, distinct functional sites, and an adjustable pore size. However, the inherent low conductivity of MOFs significantly affects the charge transfer efficiency when they are used for electrocatalytic sensing. Combining MOFs with conductive materials can compensate for these deficiencies. For MOF/metal nanoparticle composites (e.g., composites with gold, silver, platinum, and bimetallic nanoparticles), the high electrical conductivity and catalytic activity of metal nanoparticles are utilized, and MOFs can inhibit the agglomeration of nanoparticles. MOF/carbon-based material composites integrate the high electrical conductivity and large specific surface area of carbon-based materials. MOF/conductive polymer composites offer good flexibility and tunability. MOF/multiple conductive material composites exhibit synergistic effects. Although MOF composites provide an ideal platform for electrocatalytic reactions, current research still suffers from several issues, including a lack of comparative studies, insufficient research on structure–property correlations, limited practical applications, and high synthesis costs. In the future, it is necessary to explore new synthetic pathways and seek; inexpensive alternative raw materials. Full article

This study applies Gradient Boosting Machines (GBMs) and principal component regression (PCR) to forecast the closing price of the Johannesburg Stock Exchange (JSE) All-Share Index (ALSI), using daily data from 2009 to 2024, sourced from the Wall Street Journal. The models are evaluated under three training–testing split ratios to assess short-term forecasting performance. Forecast accuracy is assessed using standard error metrics: mean absolute error (MAE), root mean square error (RMSE), mean absolute percentage error (MAPE), and mean absolute scaled error (MASE). Across all test splits, the GBM consistently achieves lower forecast errors than PCR, demonstrating superior predictive accuracy. To validate the significance of this performance difference, the Diebold–Mariano (DM) test is applied, confirming that the forecast errors from the GBM are statistically significantly lower than those of PCR at conventional significance levels. These findings highlight the GBM’s strength in capturing nonlinear relationships and complex interactions in financial time series, particularly when using features such as the USD/ZAR exchange rate, oil, platinum, and gold prices, the S&P 500 index, and calendar-based variables like month and day. Future research should consider integrating additional macroeconomic indicators and exploring alternative or hybrid forecasting models to improve robustness and generalisability across different market conditions. Full article

The rapid neutron-capture process (r-process) is responsible for the creation of roughly half of the elements heavier than iron, including precious metals like silver, gold, and platinum, as well as radioactive elements such as thorium and uranium. Despite its importance, the nature of the astrophysical sites where the r-process occurs, and the detailed mechanisms of its formation, remain elusive. The key to resolving these mysteries lies in the study of chemical signatures preserved in ancient, metal-poor stars. These stars, which formed in the early Universe, retain the chemical fingerprints of early nucleosynthetic events and offer a unique opportunity to trace the origins of r-process elements in the early Galaxy. In this review, we explore the state-of-the-art understanding of r-process nucleosynthesis, focusing on the sites, progenitors, and formation mechanisms. We discuss the role of potential astrophysical sites such as neutron star mergers, core-collapse supernovae, magneto-rotational supernovae, and collapsars, that can play a key role in producing the heavy elements. We also highlight the importance of studying these signatures through high-resolution spectroscopic surveys, stellar archaeology, and multi-messenger astronomy. Recent advancements, such as the gravitational wave event GW170817 and detection of the r-process in the ejecta of its associated kilonovae, have established neutron star mergers as one of the confirmed sites. However, questions remain regarding whether they are the only sites that could have contributed in early epochs or if additional sources are needed to explain the signatures of r-process found in the oldest stars. Additionally, there are strong indications pointing towards additional sources of r-process-rich nuclei in the context of Galactic evolutionary timescales. These are several of the outstanding questions that led to the formation of collaborative efforts such as the R-Process Alliance, which aims to consolidate observational data, modeling techniques, and theoretical frameworks to derive better constraints on deciphering the astrophysical sites and timescales of r-process enrichment in the Galaxy. This review summarizes what has been learned so far, the challenges that remain, and the exciting prospects for future discoveries. The increasing synergy between observational facilities, computational models, and large-scale surveys is poised to transform our understanding of r-process nucleosynthesis in the coming years. Full article

Multidrug-resistant (MDR) biofilm infections characterized by densely packed microbial communities encased in protective extracellular matrices pose a formidable challenge to conventional antimicrobial therapies and are a major contributor to chronic, recurrent and device-associated infections. These biofilms significantly reduce antibiotic penetration, facilitate the survival of dormant persister cells and promote horizontal gene transfer, all of which contribute to the emergence and persistence of MDR pathogens. Metal nanoparticles (MNPs) have emerged as promising alternatives due to their potent antibiofilm properties. However, conventional synthesis methods are associated with high costs, complexity, inefficiency and negative environmental impacts. To overcome these limitations there has been a global push toward the development of sustainable and eco-friendly synthesis approaches. Recent advancements have demonstrated the successful use of various plant extracts, microbial cultures, and biomolecules for the green synthesis of MNPs, which offers biocompatibility, scalability, and environmental safety. This review provides a comprehensive overview of recent trends and the latest progress in the green synthesis of MNPs including silver (Ag), gold (Au), platinum (Pt), and selenium (Se), and also explores the mechanistic pathways and characterization techniques. Furthermore, it highlights the antibiofilm applications of these MNPs emphasizing their roles in disrupting biofilms and restoring the efficacy of existing antimicrobial strategies. Full article

Developments of nanostructured materials have a significant impact in various areas, such as energy technology and biomedical use. Examples include solar cells, energy management, environmental control, bioprobes, tissue engineering, biological marking, cancer diagnosis, therapy, and drug delivery. Currently, researchers are designing multifunctional nanodrugs that combine in vivo imaging (using fluorescent nanomaterials) with targeted drug delivery, aiming to maximize therapeutic efficacy while minimizing toxicity. These fascinating nanoscale “magic bullets” should be available in the near future. Inorganic nanovehicles are flexible carriers to deliver drugs to their biological targets. Most commonly, mesoporous nanostructured silica, carbon nanotubes, gold, and iron oxide nanoparticles have been thoroughly studied in recent years. Opposite to polymeric and lipid nanostructured materials, inorganic nanomaterial drug carriers are unique because they have shown astonishing theranostic (therapy and diagnostics) effects, expressing an undeniable part of future use in medicine. This review summarizes research from development to the most recent discoveries in the field of nanostructured materials and their applications in drug delivery, including promising metal-based complexes, platinum, palladium, ruthenium, titanium, and tin, to tumor cells and possible use in theranostics. Full article

Background: Incomplete eyelid closure and lagophthalmos due to facial nerve palsy are significant functional and aesthetic concerns often requiring surgical correction. The aim of this systematic review is to quantitatively assess the efficacy, safety, and patient satisfaction associated with gold or platinum weight implantation, autologous fat grafting (lipofilling), and müllerectomy. Methods: A systematic review was performed following PRISMA guidelines, searching PubMed, Embase, Cochrane Library, Web of Science, and Scopus up to March 2025. Studies included clinical data on surgical correction for incomplete eyelid closure in facial palsy, reporting functional, anatomical, and satisfaction outcomes. Quality was assessed using the Newcastle–Ottawa Scale (NOS) and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system. Results: Twenty-six studies including a total of 1205 patients were included. Gold/platinum weight implantation achieved complete or near-complete eyelid closure in 83–92% of cases, with a reduction in lagophthalmos to <1 mm. Complication rates ranged from 5–15% (mainly extrusion/migration), and patient satisfaction averaged 7.9/10. Lipofilling showed persistent benefit in 77% of cases, with 9–20% requiring repeat procedures and 10–12% experiencing minor complications. Müllerectomy yielded symptomatic improvement or resolution in 92% of cases, with a mean lagophthalmos reduction of 1.18 mm. Conclusions: Gold or platinum weight implantation provides the most reliable improvement for severe upper eyelid dysfunction in facial palsy. Lipofilling is a viable autologous alternative, while müllerectomy is effective in selected cases. Further prospective comparative trials are needed to refine surgical selection and optimize outcomes. Full article

Mineralogical variability exerts a profound influence on the flotation performance of Platinum Group Metal (PGM) ores, particularly those from the Platreef deposit, where complex associations and textures influence recovery, grade, and kinetics. This study integrates the Mode of Occurrence (MOC) and mineral associations into a modified Kelsall flotation kinetics model, optimized using a Particle Swarm Optimization (PSO) algorithm, to improve prediction accuracy. Batch flotation tests were conducted on eight samples from two lithologies—Pegmatoidal Feldspathic Pyroxenite (P-FPX) and Feldspathic Pyroxenite (FPX)—with mineralogical characterization performed using MLA, QEMSCAN, and XRD. PGMs in liberated (L) and sulfide-associated (SL) forms accounted for up to 90.6% (FPX1), exhibiting high fast-floating fractions (θ_f = 0.77–0.84) and fast flotation rate constants (K_f = 1.45–1.78 min⁻¹). In contrast, PGMs locked in silicates (G class) showed suppressed kinetics (K_f < 0.09 min⁻¹, K_s anomalies up to 8.67 min⁻¹) and were associated with lower recovery (P-FPX3 = 83.25%) and increased model error (P-FPX4 = 57.3). FPX lithologies achieved the highest cumulative recovery (FPX4 = 90.35%) and the best concentrate grades (FPX3 = 116.5 g/t at 1 min), while P-FPX1 had the highest gold content (10.45%) and peak recovery (94.37%). Grade-recovery profiles showed steep declines after 7 min, particularly in slow-floating types (e.g., P-FPX2, FPX2), with fast-floating lithologies stabilizing above 85% recovery at 20 min. The model yielded R² values above 0.97 across all samples. This validates the predictive power of MOC-integrated flotation kinetics for complex PGM ores and supports its application in geometallurgical plant design. Model limitations in capturing complex locked ore textures (SAG, G classes) highlight the need for reclassification based on floatability indices and further integration of machine learning methods. Full article

Neurodegenerative diseases (NDDs), including Alzheimer’s disease (AD) and Parkinson’s disease (PD), are characterized by progressive neuronal dysfunction and loss and represent a significant global health challenge. Oxidative stress, neuroinflammation, and neurotransmitter dysregulation, particularly affecting acetylcholine (ACh) and monoamines, are key hallmarks of these conditions. The current therapeutic strategies targeting cholinergic and monoaminergic systems have some limitations, highlighting the need for novel approaches. Metallodrugs, especially ruthenium and platinum complexes, are gaining attention for their therapeutic use. Among metal complexes, gold(I) and silver(I) N-heterocyclic carbene (NHC) complexes exhibit several biological activities, but their application in NDDs, particularly as monoamine oxidase (MAO) inhibitors, remains largely unexplored. To advance the understanding of this field, we designed, synthesized, and evaluated the biological activity of a new series of Au(I) and Ag(I) complexes stabilized by NHC ligands and bearing a carboxylate salt of tert-butyloxycarbonyl (Boc)-N-protected proline as an anionic ligand. Through in silico and in vitro studies, we assessed their potential as acetylcholinesterase (AChE) and MAO inhibitors, as well as their antioxidant and anti-inflammatory properties, aiming to contribute to the development of potential novel therapeutic agents for NDD management. Full article

This review explores the eco-friendly synthesis of metallic nanoparticles derived from polysaccharides obtained from agricultural and food industry waste. Initially, it outlines the problem of agri-food waste, highlighting its abundance and the potential to extract valuable polysaccharides such as cellulose, hemicellulose, lignin, and pectin. The focus is on green synthesis methods that use these polysaccharides to produce metallic nanoparticles, emphasizing the environmental benefits compared to conventional methods. The article reviews the physicochemical properties of key polysaccharides and details their extraction processes from various agricultural waste. The synthesis of diverse types of metallic nanoparticles, including monometallic (e.g., gold, silver, and platinum), bimetallic (e.g., gold–silver and gold–zinc), and oxide nanoparticles (e.g., zinc oxide and iron oxide), is extensively covered. Additionally, mechanisms of nanoparticle synthesis, such as nucleation, growth, stabilization, and capping, are examined, alongside examples from existing research. The article highlights the applications of these nanoparticles in diverse fields, including food safety, healthcare, agriculture, and environmental protection. It concludes by underscoring the potential of green synthesis to reduce waste and promote sustainable industrial practices and calls for further research to optimize these methods. Full article

As sustainability becomes an essential approach in the USA hospitality sector, green certifications like Leadership in Energy and Environmental Design (LEED) are increasingly adopted by hotel developers. However, the extent to which different LEED certification levels influence guest satisfaction remains unclear. This study investigates how the LEED certification level interacts with the relationship between a hotel’s sustainability performance and guest satisfaction in the United States. A mixed-methods approach was used, combining Random Forest Regression and the Process macro on a dataset of LEED-certified USA hotels with normalized guest satisfaction scores. The Random Forest model identified Energy and Atmosphere (EA) and Indoor Environmental Quality (EQ) as the most influential LEED categories in predicting satisfaction. Additionally, the results reveal that the positive effect of sustainability on satisfaction is strongest at the lower LEED levels (Certified and Silver), but shows diminishing returns at higher levels (Gold and Platinum), suggesting that an increased sustainability performance does not uniformly improve guest experience. These findings support all three hypotheses and offer practical insights for hotel developers, operators, and certification bodies seeking to align sustainability strategies with guest expectations. Full article

Standard of Care (SOC) for locally advanced cervical cancer is represented by external beam radiation therapy concurrent with platinum-based chemotherapy and immunotherapy (cCIRT) followed by brachytherapy boost and immunotherapy maintenance. In some instances, it is impossible to perform brachytherapy due to patient and/or cancer issues. In these circumstances, an external beam boost could be delivered. Using a robotic arm LINAC, it is mandatory to use intramucosal implanted fiducials which are needed for tumour tracking. To avoid invasive procedures, we developed an original intravaginal 3D-printed universal device containing gold fiducials embedded within it. In this paper, we describe the step-by-step procedure that allowed us to obtain the utility model patent, including the in vivo test (feasibility, reproducibility, device compliance) on seven patients within the study protocol “STereotActic Radiotherapy Boost in locally Advanced Cervical carcinoma patientS” (STARBACS). Full article

The spontaneous deposition of platinum ($Pt$) atoms on $Au\left(111\right)$ surfaces is systematically investigated through kinetic Monte Carlo simulations within the Embedded Atom Model framework. The kinetic model aims to capture both stoichiometric, atomic-scale interactions and the more relevant processes that describe the kinetics of a physical problem. Various deposition rates are examined, encompassing a thorough exploration of $Pt$ adsorption up to a coverage degree of $\theta =0.25$. The resulting 2D islands exhibit a ramified structure, mirroring the experimental methodologies. For the first time, this study extensively analyzes the dependence of both the mean island size and island density on spontaneous deposition, thereby offering valuable insights into the intricate dynamics of the system. Full article

In this work, two series of Au(III) and Pt(II) alkynylphosphonium complexes of composition [M(CNC)(C₂−L−P(CH₃)Ph₂)]ⁿ⁺ Pt1–Pt3 (n = 0) and Au1–Au3 (n = 1), (CNC = 2,6-diphenylpyridine; L = phenyl, biphenyl, naphthyl) were synthesized and characterized to discover the similarities and differences in photophysical properties between isoelectronic metallocentres. It is shown that Au(III) and Pt(II) complexes obtained demonstrate different photophysical properties despite isoelectronic metal centres, and some reasons for that are discussed based on experimental data and quantum-chemical calculation results. Complex Pt1 also demonstrated the first example of room-temperature solution phosphorescence in the family of [Pt(CNC)(alkynyl)] complexes. It has been found that the crystal packing of Pt1 contains a Pt–H interaction, qualified by quantum-chemical calculations as a unique hydrogen bond. Full article

The control of elemental impurities is a critical step in the preparation of lanthanum carbonate, with platinum being one such impurity. Residual platinum is typically non-therapeutic and must be strictly controlled to ensure both safety and product quality. This paper describes a colorimetric method for determining platinum (IV) in solutions based on the anti-aggregation of gold nanoparticles modified with 4-methylsulfonylaniline (4-MESA). The presence of Britton–Robinson buffer induces the aggregation of the 4-MESA-AuNPs nanoparticle probe. However, when platinum (IV) is introduced, it disrupts the aggregation of the 4-MESA-AuNPs, causing a color change in the solution. The absorbance at 524 nm showed a strong linear correlation in the concentration range of 1.00 × 10⁻² μM to 5.00 × 10² μM. Under optimal conditions, LOD and LOQ values of 10.00 × 10⁻³ μM and 3.03 × 10⁻² μM, respectively, were observed. This method has been successfully applied to the determination of platinum (IV) in lanthanum carbonate API. Full article

Bacterial infections are the primary cause of mastitis in dairy cattle. Fungal mastitis occurs in 1–12% of cases. Antibiotic therapy, the standard treatment for mastitis, has led to antibiotic-resistant bacteria, reducing treatment efficacy and increasing fungal mastitis occurrence. Antibiotics lack biocidal effects on fungi, which often exhibit resistance to antifungal agents. This study evaluated the antifungal properties of nanoparticles (NPs) against Candida albicans, Candida glabrata, Candida parapsilosis, Diutina rugosa var. rugosa, Diutina catenulata, and Diutina rugosa. Tested NPs included gold (AuNPs), silver (AgNPs), copper (CuNPs), iron with hydrophilic carbon coating (FeCNPs) (1.56–25 mg/L), and platinum (PtNPs) (0.625–10 mg/L), along with their complexes. Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) at 0.75–25 mg/L for AuNPs, AgNPs, CuNPs, and FeCNPs and 0.313–10 mg/L for PtNPs, as well as fungal sensitivity to standard antifungals, were determined. Each strain showed different sensitivities depending on the NPs used and their concentrations. C. glabrata was the most resistant to nanoparticles, while D. catenulata was the most susceptible. PtNPs and FeCNPs showed no or weak biocidal properties. Some mycotic-resistant strains were sensitive to nanoparticles. This study indicates a high in vitro antifungal potential for the application of nanoparticles, especially AgCuNPs, as a new effective non-antibiotic agent for the prevention and control of mycotic mastitis in dairy cattle. Full article