Search Results (427)

Esterification is a key transformation in the production of lubricants, pharmaceuticals, and fine chemicals. Conventional processes employing homogeneous acid catalysts suffer from limitations such as corrosive byproducts, energy-intensive separation, and poor catalyst reusability. This review provides a comprehensive overview of heterogeneous catalytic systems, including ion exchange resins, zeolites, metal oxides, mesoporous materials, and others, for improved ester synthesis. Recent advances in membrane-integrated reactors, such as pervaporation and nanofiltration, which enable continuous water removal, shifting equilibrium and increasing conversion under milder conditions, are reviewed. Dual-functional membranes that combine catalytic activity with selective separation further enhance process efficiency and reduce energy consumption. Enzymatic systems using immobilized lipases present additional opportunities for mild and selective reactions. Future directions emphasize the integration of pervaporation membranes, hybrid catalyst systems combining biocatalysts and metals, and real-time optimization through artificial intelligence. Modular plug-and-play reactor designs are identified as a promising approach to flexible, scalable, and sustainable esterification. Overall, the interaction of catalyst development, membrane technology, and digital process control offers a transformative platform for next-generation ester synthesis aligned with green chemistry and industrial scalability. Full article

This study presents a photoresist-free patterning method for solution-processed indium zinc oxide (IZO) thin films using two photochemical exposure techniques, namely pulsed ultraviolet (UV) light and UV-ozone, and a plasma-based method using oxygen (O₂) plasma. Pulsed UV light delivers short, high-intensity flashes of light that induce localised photochemical reactions with minimal thermal damage, whereas UV-ozone enables smooth and uniform surface oxidation through continuous low-pressure UV irradiation combined with in situ ozone generation. By contrast, O₂ plasma generates ionised oxygen species via radio frequency (RF) discharge, allowing rapid surface activation, although surface damage may occur because of energetic ion bombardment. All three approaches enabled pattern formation without the use of conventional photolithography or chemical developers, and the UV-ozone method produced the most uniform and clearly defined patterns. The patterned IZO films were applied as active layers in bottom-gate top-contact thin-film transistors, all of which exhibited functional operation, with the UV-ozone-patterned devices exhibiting the most favourable electrical performance. This comparative study demonstrates the potential of photochemical and plasma-assisted approaches as eco-friendly and scalable strategies for next-generation IZO patterning in electronic device applications. Full article

The Carboniferous–Permian tight sandstone gas reservoirs in the Shenfu area of the Ordos Basin in China are characterized by the widespread development of multiple formations. However, significant differences exist among the tight sandstones of different formations, and their formation mechanisms and key controlling factors remain unclear, hindering the effective selection and development of favorable tight gas intervals in the study area. Through comprehensive analysis of casting thin section (CTS), scanning electron microscopy (SEM), cathodoluminescence (CL), X-ray diffraction (XRD), particle size and sorting, porosity and permeability data from Upper Paleozoic tight sandstone samples, combined with insights into depositional environments, burial history, and chemical reaction processes, this study clarifies the characteristics of tight sandstone reservoirs, reveals the key controlling factors of reservoir quality, confirms the differential evolutionary mechanisms of tight sandstone of different formations, reconstructs the diagenetic sequence, and constructs an evolution model of reservoir minerals and porosity. The research results indicate depositional processes laid the foundation for the original reservoir properties. Sandstones deposited in tidal flat and deltaic environments exhibit superior initial reservoir qualities. Compaction is a critical factor leading to the decline in reservoir quality across all formations. However, rigid particles such as quartz can partially mitigate the pore reduction caused by compaction. Early diagenetic carbonate cementation reduces reservoir quality by occupying primary pores and hindering the generation of secondary porosity induced by acidic fluids, while later-formed carbonate further densifies the sandstone by filling secondary intragranular pores. Clay mineral cements diminish reservoir porosity and permeability by filling intergranular and intragranular pores. The Shanxi and Taiyuan Formations display relatively poorer reservoir quality due to intense illitization. Overall, the reservoir quality of Benxi Formation is the best, followed by Xiashihezi Formation, with the Taiyuan and Shanxi Formations exhibiting comparatively lower qualities. Full article

Recycled concrete fines (RCFs) have the potential to serve as a supplementary cementitious material (SCM) after carbonation. Traditionally, carbonation of RCFs results in calcium carbonate primarily in the form of calcite, which significantly limits the development of RCFs as an SCM. In this research, a wet grinding carbonation (WGC) technique was introduced to enhance the reactivity of RCFs. The research indicates that RCFs after WGC exhibit a finer particle size and a larger specific surface area. The carbonation products include calcite with smaller grains, metastable calcium carbonate, and nanoscale silica gel and Al-Si gel. When RCF-WGC is used as an SCM in ordinary Portland cement (OPC), it significantly promotes the hydration of the cement paste, as evidenced by the advancement and increased intensity of the exothermic peaks of aluminates and silicates. RCF-WGC can significantly enhance the compressive strength of hydrated samples, particularly at early ages. Specifically, at a curing age of 1 day, the compressive strength of WGC5, WGC10, and WGC20 samples increased by 9.9%, 22.5%, and 7.7%, respectively, compared to the Ref sample (0% RCF-WGC). At a curing age of 3 days, the compressive strength of the WGC5, WGC10, and WGC20 samples showed even more significant improvements, increasing by 20.8%, 21.9%, and 11.8%, respectively. The performance enhancement of the WGC samples is attributed to the chemical reactions involving nanoscale silica gel, Al-Si gel, and calcium carbonate in the RCFs. When RCF-WGC is used as an SCM to replace 5%, 10%, and 20% of cement, it can reduce carbon emissions by 27.5 kg/t, 55 kg/t, and 110 kg/t, respectively. Large-scale application of RCFs as a high-value SCM can significantly reduce the life-cycle carbon emissions of the cement industry, contributing to the achievement of carbon peaking in China’s cement sector. Full article

Background and Objectives: Previous studies have shown that a major part of adverse drug reactions (ADRs) are preventable, and they contribute to increased morbidity, mortality, and costs. To our knowledge, no study investigating preventable ADRs has been carried out in Lithuania. Therefore, the aim of this study was to characterize ADRs in the intensive care unit (ICU) of a secondary care Lithuanian hospital as well as to identify drug classes and organ systems most commonly implicated in preventable and nonpreventable ADRs. Materials and Methods: This observational prospective study was conducted in an 18-bed ICU of Kaunas Hospital of the Lithuanian University of Health Sciences from 1 September 2021 to 31 August 2023. All ADRs were assessed for causality, severity, and preventability. The Anatomical Therapeutic and Chemical (ATC) system was used to classify drug classes implicated in ADRs. The organ systems affected were analyzed using the Medical Dictionary for Regulatory Activities (MedDRA). Results: A total of 154 patients with a median age of 78.8 years (range, 18–97) were enrolled into this study. There were 255 ADRs identified; preventable ADRs accounted for 87.5%. Among the preventable ADRs, the top three therapeutic subgroups were antithrombotic agents (26.5%), anti-inflammatory and antirheumatic products (22.0%), and blood substitutes and perfusion solutions (20.2%). Meanwhile, among nonpreventable ADRs, antibacterials for systemic use (62.5%) and antithrombotic agents (46.9%) were the two most common therapeutic subgroups. The gastrointestinal as well as the skin and subcutaneous tissues organ systems were more likely to be affected by nonpreventable ADRs (56.3% vs. 17.5%, p ˂ 0.05 and 12.5% vs. 0.4%, p ˂ 0.05, respectively), while the renal and urinary organ systems were more likely to be affected by preventable ADRs (38.1% vs. 6.3%, p ˂ 0.05). Conclusions: Our study showed a very high incidence of preventable ADRs (87.5%). Drugs affecting blood and blood-forming organs were most frequently implicated in these ADRs. This area deserves special attention and strategies need to be implemented to reduce the incidence of preventable ADRs and their impact on the healthcare system. Moreover, it emphasizes the need for future studies at a national level as, to our knowledge, this is the first study addressing the issues of avoidable harm at the ICU of one Lithuanian hospital. Full article

The starch modification of mango cotyledons with both single ultrasound (US) and dual (US followed by octenyl succinic anhydride, OSA) was optimized by response surface methodology (RSM). The mechanochemical effects of ultrasound on amylose content, particle size, and dual modification efficiency were assessed. In addition, the structural, thermal, morphological, and functional properties were evaluated. After optimization with single US (41 min and 91% sonication intensity), sonication induced starch granule fragmentation, altering amorphous and partially crystalline regions, which increased amylose content (34%), reduced particle size (Dx50 = 12 μm), and modified granule surface morphology. The dual modification (the subsequent OSA reaction lasted 4.6 h under the same conditions) reached a degree of substitution of 0.02 and 81% efficiency, imparting amphiphilic properties to the starch. OSA groups were mainly incorporated into amorphous and surface regions, which decreased crystallinity, gelatinization temperature, and enthalpy. The synergistic effect of the modification with US and OSA in the dual modification significantly improved the solubility and swelling power of starch, resulting in better dispersion, functionality in aqueous systems, and chemical reactivity. These findings highlight the potential of dual modification to transform mango cotyledon starch into a versatile ingredient in the food industry as a thickener, a stabilizer in soups and sauces, an emulsifier, a carrier of bioactive and edible films; in the cosmetic industry as a gelling and absorbent agent; and in the pharmaceutical industry for the controlled release of drugs. Furthermore, valorizing mango cotyledons supports circular economy principles, promoting sustainable and value-added food product development. Full article

Enhanced or engineered geothermal systems (EGSs), or non-hydrothermal resources, are highly notable among sustainable energy resources because of their abundance and cleanness. The EGS concept has received worldwide attention and undergone intensive studies in the last decade in the US and around the world. In comparison, hydrothermal reservoir resources, the ‘low-hanging fruit’ of geothermal energy, are very limited in amount or availability, while EGSs are extensive and have great potential to supply the entire world with the needed energy almost permanently. The EGS, in essence, is an engineered subsurface heat mining concept, where water or another suitable heat exchange fluid is injected into hot formations to extract heat from the hot dry rock (HDR). Specifically, the EGS relies on the principle that injected water, or another working fluid, penetrates deep into reservoirs through fractures or high-permeability channels to absorb large quantities of thermal energy by contact with the host hot rock. Finally, the heated fluid is produced through production wells for electricity generation or other usages. Heat mining from fractured EGS reservoirs is subject to complex interactions within the reservoir rock, involving high-temperature heat exchange, multi-phase flow, rock deformation, and chemical reactions under thermal-hydrological-mechanical (THM) processes or thermal-hydrological-mechanical-chemical (THMC) interactions. In this paper, we will present a THM model and reservoir simulator and its application for simulation of hydrothermal geothermal systems and EGS reservoirs as well as a methodology of coupling thermal, hydrological, and mechanical processes. A numerical approach, based on discretizing the thermo-poro-elastic Navier equation using an integral finite difference method, is discussed. This method provides a rigorous, accurate, and efficient fully coupled methodology for the three (THM) strongly interacted processes. Several programs based on this methodology are demonstrated in the simulation cases of geothermal reservoirs, including fracture aperture enhancement, thermal stress impact, and tracer transport in a field-scale reservoir. Results are displayed to show geomechanics’ impact on fluid and heat flow in geothermal reservoirs. Full article

Hydrogen peroxide (H₂O₂) is an important industrial chemical that is widely applied in many areas. The direct synthesis of H₂O₂ from H₂ and O₂ has proved to be a green and economic pathway. Pd-based bimetallic catalysts, due to their superior catalytic performances in this reaction, have attracted intensive attention. Herein, Tetrakis(hydroxymethyl)phosphonium chloride (THPC) was adopted as the protective ligand to immobilize Pd-Au alloy nanoparticles onto activated carbon (AC). The varied Pd/Au molar ratios demonstrated homogeneously distributed Pd-Au nanoalloys with average particle sizes ranging from 3.51 to 5.75 nm. The optimal ratio was observed over the Pd₃Au₁/AC-THPC catalyst with a maximum H₂O₂ productivity of 165 mol/(kg_Pd·h) and selectivity of 82.3% under ambient pressure. The relationship between the electronic structure and catalytic activity indicated Pd⁰ was the active site, while the presence of Au inhibited H₂O₂ degradation rate. This research could help in the design efficient bimetallic catalysts for the direct synthesis of H₂O₂. Full article

Rainwater needs to be recognized as a natural water source for domestic use, but finding viable processes to remove its contaminants is essential. The aim of this work was to compare the UV/H₂O₂ and UV/Fenton-like processes for the oxidation of 3,5-dihydroxybenzoic acid (3,5-DHBA) in rainwater. The reactions were assessed using ultraviolet-visible (UV-Vis) and molecular fluorescence spectroscopies, and the results showed the formation of new and similar chromophoric compounds in both processes, which were subsequently degraded. At environmentally relevant concentrations of chemical oxidants, namely H₂O₂ at 10⁻⁴ M, the chromophoric organic compounds in solution were degraded within 24 h by the UV/H₂O₂ process and within 4 h by the UV/Fenton-like process. However, when the concentration of H₂O₂ was increased by one order of magnitude for the UV/H₂O₂ process (from 10⁻⁴ M to 10⁻³ M), oxidation rates were similar and nearly complete after 4 h for both UV/H₂O₂ and UV/Fenton-like processes. These findings highlight that the presence of more oxidizing agents in the oxidation system improves the synergistic effect, leading to a greater contribution of the free radical oxidation pathway, particularly through hydroxyl radicals. Thus, by increasing the concentration of H₂O₂ in the UV/H₂O₂ process to 10⁻³ M, it was possible to achieve a similar level of oxidation (close to 100% after 4 h, as indicated by a decrease in fluorescence intensity) as the UV/Fenton-like process at environmentally relevant concentrations (10⁻⁴ M), but using fewer chemical reactants, since UV/H₂O₂ process does not require Fe(III) as catalyst and oxidant. Therefore, the UV/H₂O₂ process can be considered a simpler and cleaner process for removing organic contaminants from rainwater. Full article

As an important ecological barrier in the upper reaches of the Yangtze River, the Jialing River Basin has complex and sensitive hydrochemical evolutionary mechanisms due to its geological structures and human activities. This study focuses on the groundwater in the Wusheng section of the Jialing River Basin, combining field investigations and Entropy-Weighted Water Quality Index (EWQI) calculations to analyze its hydrochemical characteristics and influencing factors and conduct a water quality assessment. The results show that this regional water body has a pH of 7.05–8.36, presenting weakly alkaline and low-mineralization characteristics, with differences in hydrochemical components between groundwater and surface water. The ions are predominantly controlled by rock weathering, with reactions such as halite and gypsum dissolution occurring during groundwater runoff. Groundwater in the tectonic influence zone exhibits abnormal chemical compositions due to lateral recharge from different strata along fracture channels and long-distance runoff reactions with the surrounding rocks. EWQI values for groundwater range from 6.07 to 104.02, with an average value of 37.46, generally exhibiting a trend of increasing EWQI values near the Jialing Riverbank. In this area, 96.15% of groundwater meets excellent or good quality standards and is suitable for direct drinking. The influence of the intensity of different indicators on groundwater quality decreases in the order of Ca²⁺ > Cl⁻ > Mg²⁺ > SO₄²⁻ > HCO₃⁻ > NO₃⁻. Water quality is primarily influenced by the primary geological background, while agricultural practices may also lead to its deterioration. Full article

High-order harmonic generation provides a powerful tool for probing ultrafast chemical dynamics, such as electron transfer, bond breaking, and molecular structural changes, with attosecond temporal resolution. The strong laser fields used in HHG can also directly influence chemical reaction pathways and rates, enabling coherent control of reaction selectivity. However, enhancing the efficiency of harmonic emission remains a critical challenge in ultrafast science. In this study, we investigate the effects of molecular size and orientation on HHG efficiency using time-dependent density functional theory simulations. By analyzing the linear molecules ${\mathrm{C}}_{18}{\mathrm{H}}_2$, ${\mathrm{C}}_2{\mathrm{H}}_2$, and C₁₀H₂ under linearly polarized laser fields, we demonstrate that larger molecular sizes significantly enhance harmonic emission intensity. Our results reveal that ${\mathrm{C}}_{18}{\mathrm{H}}_2$, with its larger spatial dimensions, exhibits substantially higher harmonic intensity compared to smaller molecules like ${\mathrm{C}}_2{\mathrm{H}}_2$. This enhancement is further supported by examining charge redistribution and bond length changes during the HHG process. Additionally, we validate our findings with C₁₀H₂, a molecule of intermediate size, confirming the correlation between molecular size and harmonic efficiency. Full article

The toxicity associated with bongkrekic acid (BKA) is severe due to its chemical structure, which also facilitates high mortality rates; however, its isomer, isobongkrekic acid (iBKA), with only minor structural variance, demonstrates marked differences in toxicity. This discrepancy in structural properties and toxicity highlights that risks have been potentially underestimated within current detection standards for BKAs. In this study, a novel BKA trans isomer at the C8 and C9 double carbon bonds (E-configuration), termed iBKA-neo, was successfully separated and identified. Subsequently, the multiple reaction monitoring parameters and chromatographic conditions for three BKA isomers were optimized, enabling effective separation within 15 min via UHPLC-MS/MS, among which the ammonium positive adduct ions yielded significantly higher response intensities for all BKA isomers than traditional deprotonated molecules. Additionally, distinct differences in the ion ratios between iBKA-neo and BKA were utilized for preliminary screening. On this basis, the extraction and enrichment strategies for BKAs were optimized in food matrices and validated comprehensively with good linearity (0.25–500 μg/kg), a superior limit of quantification (0.25 μg/kg), acceptable recoveries (82.32–114.84%), and stable intraday and interday precision (an RSD less than 12.67%). These findings significantly contribute to ecotoxicology and the formulation of safety standards concerning BKAs. Full article

As coal resources deplete and deep mining in high-stress environments becomes more challenging, ensuring safety and sustainability in coal production is a growing concern. This study investigates the dynamic of external load on the oxidation kinetics of coal in goaf, focusing on the resulting physical and chemical changes. Thermogravimetric (TG), differential thermogravimetric (DTG), and differential scanning calorimetry (DSC) tests were conducted on long-flame coal samples under varying hammer-drop heights. Impact-loaded coal shows a shorter reaction time, higher peak intensity, and lower apparent activation energy than untreated coal. These effects intensify with increasing drop height, resulting in a 13–40% reduction in apparent activation energy. A six-step reaction pathway for pyrolysis and oxidation was developed, and kinetics parameters were determined using genetic algorithms (GA). GA-based inverse modeling produced a comprehensive reaction model for coal oxidation under dynamic load. This work presents a detailed kinetic model for coal oxidation under impact, contributing to better understanding the challenges of safety and sustainability in deep coal mining. Full article

The ecological impact linked to hydraulic fracturing, namely with the usage of water and the energy-intensive disposal of flowback fluids, has led to a thorough evaluation of alternative treatment approaches that are more environmentally friendly. The objective of this work was to create coralline-like anatase TiO₂/α-Ni(OH)₂ particles using a hydrothermal approach. The purpose was to improve the efficiency of photocatalysis by increasing the number of oxygen vacancies. An ozone-assisted photocatalytic reaction was used to increase the composite photocatalyst’s degrading efficiency for fracturing flowback fluid. The fracturing flowback fluid’s chemical oxygen demand (COD) degradation efficiency was greatly increased following the introduction of the synergistic treatment system consisting of sedimentation, membrane separation, and ozone photocatalysis. This improvement led to a reduction of 98.42% during a processing time of 90 min, using a Ti/Ni mass ratio of 1:1. This collaborative method partially replaced traditional methods of evaporation concentration and electrochemical degradation, resulting in a 24.18% enhancement compared to individual material catalyst systems. These findings provide crucial insights for improving and optimizing external treatment techniques in shale gas fracturing operations. Full article

This study investigates magnetohydrodynamic (MHD) heat and mass transport in a water-based ternary hybrid nanofluid flowing past an exponentially accelerated vertical porous plate. Two critical scenarios are analyzed: (i) uniform heat flux with variable mass diffusion and (ii) varying heat source with constant species diffusion. The model integrates thermal radiation, heat sink/source, thermal diffusion, and chemical reaction effects to assess flow stability and thermal performance. Governing equations are non-dimensionalized and solved analytically using the Laplace transform method, with results validated against published data and finite difference method outcomes. Ternary hybrid nanofluids exhibit a significantly higher Nusselt number compared to hybrid and conventional nanofluids, demonstrating superior heat transfer capabilities. Magnetic field intensity reduces fluid velocity, while porosity enhances momentum transfer. Thermal radiation amplifies temperature profiles, critical for energy systems. Concentration boundary layer thickness decreases with higher chemical reaction rates, optimizing species diffusion. These findings contribute to the development of advanced thermal management systems, such as solar energy collectors and nuclear reactors, enhance energy-efficient industrial processes, and support biomedical technologies that require precise heat and mass control. This study positions ternary hybrid nanofluids as a transformative solution for optimizing high-performance thermal systems. Full article