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Achieving no or low polychlorinated byproduct selectivity is essential for the chlorinated volatile organic compounds (CVOCs) degradation, and the positive roles of water vapor may contribute to this goal. Herein, the oxidation behaviors of chlorobenzene over typical Mn-based catalysts (MnO2 and acid-modified MnO2) under dry and humid conditions were fully explored. The results showed that the presence of water vapor significantly facilitates the deep mineralization of chlorobenzene and restrains the formation of Cl2 and dichlorobenzene. This remarkable water vapor-promoting effect was conferred by the MnO2 substrate, which could suitably synergize with the postconstructed acidic sites, leading to good activity, stability, and desirable product distribution of acid-modified MnO2 catalysts under humid conditions. A series of experiments including isotope-traced (D2O and H218O) CB-TPO provided complete insights into the direct involvement of water molecules in chlorobenzene oxidation reaction and attributed the root cause of the water vapor-promoting effect to the proton-rich environment and highly reactive water-source oxygen species rather than to the commonly assumed cleaning effect or hydrogen proton transfer processes (generation of active OOH). This work demonstrates the application potential of Mn-based catalysts in CVOCs elimination under practical application conditions (containing water vapor) and provides the guidance for the development of superior industrial catalysts.
Assuntos
Óxidos , Vapor , Catálise , Clorobenzenos/química , Compostos de Manganês , Óxidos/química , PrótonsRESUMO
The interaction between Cu and Mn has been used to immobilize the Cu single-atom on MnO2 surface by redox-driven hydrolysis. Comprehensive structure and property characterizations demonstrate that the existence of an Cu-Mn interaction on the catalyst surface can effectively restrain the aggregation of Cu single atoms and improve carbon monoxide (CO) oxidation activity. The interaction of forming the Cu-O-Mn entity is beneficial for CO catalytic activity as the migration of reactive oxygen species and the coordination effect of active centers accelerate the reaction. In particular, 3%-Cu1 /MnO2 shows an oxygen storage capacity (OSC) value (342.75â µmol/g) more than ten times that of pure MnO2 (27.79â µmol/g) and has high CO catalytic activity (T90% =80 °C), it can maintain CO conversion of 95 % after 15 cycles. This work offers a reliable method for synthesizing Cu single-atom catalysts and deepens understanding of the interaction effect between single transition metal atoms and supports that can improve the catalytic activity of CO oxidation.
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Single-atom noble metals on a catalyst support tend to migrate and agglomerate into nanoparticles owing to high surface free energy at elevated temperatures. Temperature-induced structure reconstruction of a support can firmly anchor single-atom Pt species to adapt to a high-temperature environment. We used Mn3 O4 as a restructurable support to load single-atom Pt and further turned into single-atom Pt-on-Mn2 O3 catalyst via high-temperature treatment, which is extremely stable under calcination conditions of 800 °C for 5â days in humid air. High-valence Pt4+ with more covalent bonds on Mn2 O3 are essential for anchoring isolated Pt atoms by strong interaction. An optimized catalyst formed by moderate H2 O2 etching exhibits the best performance and excellent thermal stability of single-atom Pt in high-temperature CH4 oxidation on account of more exposed Pt atoms and strong Pt-Mn2 O3 interaction.
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A novel method of redox precipitation was applied for the first time to synthesize a Au-doped α-MnO2 catalyst with high dispersion of the Au species. Au nanoparticles (NPs) can be downsized into approximate single atoms by this method, thereby realizing highly efficient utilization of Au element as well as satisfying low-temperature oxidation of formaldehyde (HCHO). Under catalysis of the optimal 0.25% Au/α-MnO2 catalyst, a polluted stream containing 500 ppm HCHO can be completely cleaned at 75 °C with the condition of a weight hourly space velocity (WHSV) of 60000 mL/(g h). Meanwhile, the catalyst retains good activity for removal of low-concentration HCHO (about 1 ppm) at ambient temperature with a high WHSV, and exhibits a high tolerance to water and long-term stability. Our characterization of Au/α-MnO2 and catalytic performance tests clearly demonstrate that the proper amount of Au doping facilitates formation of surface vacancy oxygen, lattice oxygen, and charged Au species as an active site, which are all beneficial to catalytic oxidation of HCHO. The oxidation of HCHO over Au-doped α-MnO2 catalyst obeys the Mars-van Krevelen mechanism as evidenced by in situ diffuse reflectance infrared Fourier transform spectroscopy.
Assuntos
Formaldeído , Nanopartículas Metálicas , Ouro , Oxirredução , TemperaturaRESUMO
In this study, a core-shell structural nano-composite material, namely CdTeS@SiO2, is synthesized by a simple silanization of Te-doped CdS quantum dots (CdTeS QDs). Through SiO2 capping, CdTeS QDs not only improve the fluorescence performance effectively, but also greatly enhance the anti-interference ability in the environment. Based on its excellent optical properties, a novel fluorescence sensor is constructed for the ultramicro detection of Ag+. The fluorescence of CdTeS@SiO2 is strongly quenched in the presence of Ag+ and shows good linearity in the range of 0.005-5.0 µmol L-1 with a detection limit as low as 1.6 nmol L-1. This is mainly due to its unique quenching mechanism: Ag+ destroys the spherical structure of SiO2 and promotes the formation of non-radiative electron-hole pairs through electron transfer, leading to fluorescence quenching. At the same time, it competes with Cd for Te, S and MPA on the CdTeS surface, forming Ag-Te, Ag-S and Ag-MPA complexes attached to the CdTeS surface leading to wavelength red-shift. The feasibility of the proposed sensor is demonstrated through spiking experiments, which confirmed the potential value of the constructed fluorescence probe for real-world applications in detecting Ag+ in environmental water.
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Cardiovascular diseases (CVDs) are the leading cause of death globally, resulting in a major health burden. Thus, an urgent need exists for exploring effective therapeutic targets to block progression of CVDs and improve patient prognoses. Immune and inflammatory responses are involved in the development of atherosclerosis, ischemic myocardial damage responses and repair, calcification, and stenosis of the aortic valve. These responses can involve both large and small blood vessels throughout the body, leading to increased blood pressure and end-organ damage. While exploring potential avenues for therapeutic intervention in CVDs, researchers have begun to focus on immune metabolism, where metabolic changes that occur in immune cells in response to exogenous or endogenous stimuli can influence immune cell effector responses and local immune signaling. Itaconate, an intermediate metabolite of the tricarboxylic acid (TCA) cycle, is related to pathophysiological processes, including cellular metabolism, oxidative stress, and inflammatory immune responses. The expression of immune response gene 1 (IRG1) is upregulated in activated macrophages, and this gene encodes an enzyme that catalyzes the production of itaconate from the TCA cycle intermediate, cis-aconitate. Itaconate and its derivatives have exerted cardioprotective effects through immune modulation in various disease models, such as ischemic heart disease, valvular heart disease, vascular disease, heart transplantation, and chemotherapy drug-induced cardiotoxicity, implying their therapeutic potential in CVDs. In this review, we delve into the associated signaling pathways through which itaconate exerts immunomodulatory effects, summarize its specific roles in CVDs, and explore emerging immunological therapeutic strategies for managing CVDs.
Assuntos
Doenças Cardiovasculares , Succinatos , Humanos , Succinatos/metabolismo , Animais , Doenças Cardiovasculares/metabolismo , Doenças Cardiovasculares/imunologia , Doenças Cardiovasculares/tratamento farmacológico , Doenças Cardiovasculares/patologia , Ciclo do Ácido Cítrico , Estresse Oxidativo/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , CarboxiliasesRESUMO
Diabetes mellitus (DM) is a serious chronic metabolic disease that can lead to many serious complications, such as cardiovascular disease, retinopathy, neuropathy, and kidney disease. Once diagnosed with diabetes, patients need to take oral hypoglycemic drugs or use insulin to control blood sugar and slow down the progression of the disease. This has a significant impact on the daily life of patients, requiring constant monitoring of the side effects of medication. It also imposes a heavy financial burden on individuals, their families, and even society as a whole. Adipose-derived stem cells (ADSCs) have recently become an emerging therapeutic modality for DM and its complications. ADSCs can improve insulin sensitivity and enhance insulin secretion through various pathways, thereby alleviating diabetes and its complications. Additionally, ADSCs can promote tissue regeneration, inhibit inflammatory reactions, and reduce tissue damage and cell apoptosis. The potential mechanisms of ADSC therapy for DM and its complications are numerous, and its extensive regenerative and differentiation ability, as well as its role in regulating the immune system and metabolic function, make it a powerful tool in the treatment of DM. Although this technology is still in the early stages, many studies have already proven its safety and effectiveness, providing new treatment options for patients with DM or its complications. Although based on current research, ADSCs have achieved some results in animal experiments and clinical trials for the treatment of DM, further clinical trials are still needed before they can be applied in a clinical setting.
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Diabetes Mellitus Experimental , Animais , Humanos , Diabetes Mellitus Experimental/metabolismo , Tecido Adiposo , Adipócitos/metabolismo , Glicemia/metabolismo , Células-Tronco/metabolismoRESUMO
Magnetic bentonite is modified by an amphoteric surfactant (dodecyl dimethyl betaine, BS-12), then modified by a cationic surfactant (Cetyl Trimethyl Ammonium Bromide, CTMAB) and anionic surfactant (Sodium lauryl sulfonate, SDS). Amphoteric-cationic modified magnetic bentonite (BS-CT-MBT) and amphoteric-anionic modified magnetic bentonite (BS-SDS-MBT) are obtained. Structural identification of the samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analyses (TG), Fourier transform infrared spectra (FTIR), and vibrating sample magnetometer (VSM). The carbon-nitrogen content, specific surface area, and pore volume were also evaluated. Batch isotherm studies were conducted to evaluate the sorption of phenol. The results show that BS-CT-MBT and BS-SDS-MBT can be separated by magnetic separation. The carbon content-nitrogen content and content of surfactants of the BS-CT-MBT increase, while surface area and pore volume decrease compared to those of BS-MBT. Compared with BS-MBT, the carbon-nitrogen content, content of surfactants, and pore volume of BS-SDS-MBT are decreasing and surface area is increasing. The desorption rate of the surfactants is less than 9% at pH 6.0 and in 0.1 mol·L-1 NaCl solution. The Henry equation is the optimal description for the phenol sorption isotherms, implying a partitioning sorption process. The amount of phenol sorption follows the order:BS-CT-MBT > BS-MBT > BS-SDS-MBT > BT > MBT, which significantly correlates with the variation of the content of surfactant. Amphoteric magnetic bentonites modified by CTMAB have better absorption performance for phenol than those modified by SDS.
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An ozone and ozone/peroxide oxidation process was evaluated at pilot scale for trace organic contaminant (TOrC) mitigation and NDMA formation in both drinking water and water reuse applications. A reverse osmosis (RO) pilot was also evaluated as part of the water reuse treatment train. Ozone/peroxide showed lower electrical energy per order of removal (EEO) values for TOrCs in surface water treatment, but the addition of hydrogen peroxide increased EEO values during wastewater treatment. TOrC oxidation was correlated to changes in UV(254) absorbance and fluorescence offering a surrogate model for predicting contaminant removal. A decrease in N-nitrosodimethylamine (NDMA) formation potential (after chloramination) was observed after treatment with ozone and ozone/peroxide. However, during spiking experiments with surface water, ozone/peroxide achieved limited destruction of NDMA, while in wastewaters net direct formation of NDMA of 6-33 ng/L was observed after either ozone or ozone/peroxide treatment. Once formed during ozonation, NDMA passed through the subsequent RO membranes, which highlights the significance of the potential for direct NDMA formation during oxidation in reuse applications.
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Água Potável/química , N-Metilaspartato/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Reatores Biológicos , Água Potável/análise , Peróxido de Hidrogênio/química , Membranas/química , N-Metilaspartato/análise , Nevada , Compostos Orgânicos/análise , Compostos Orgânicos/química , Osmose , Oxirredução , Ozônio/química , Poluentes Químicos da Água/análise , Purificação da Água/instrumentaçãoRESUMO
Surface coatings developed in different natural waters were used to study the role of the composition of surface coatings in controlling Cd adsorption in aquatic environments. To investigate the adsorption property of each component, the method of extraction techniques followed by Cd adsorption and statistical analysis were employed. Hydroxylamine hydrochloride was used to remove Mn oxides selectively, sodium dithionite was used to remove Mn and Fe oxides, and oxalic acid was used to remove most metal oxides and part of the organic material. Adsorption of Cd to surface coatings was measured before and after extraction under controlled laboratory conditions. The observed Cd adsorptions to unextracted and extracted surface coatings were analyzed using nonlinear least-squares fitting to estimate the adsorption property of each surface coating constituent. In different waters, the relative contribution to Cd adsorption of each component was different, but in all the waters studied, ferromanganese oxides contributed most with lesser roles indicated for organic phase and Al oxides. The Cd adsorption ability of manganese oxides was significantly higher than that of the other components.