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1.
Nat Commun ; 12(1): 1728, 2021 03 19.
Artículo en Inglés | MEDLINE | ID: mdl-33741927

RESUMEN

Microsomal glutathione S-transferase 2 (MGST2) produces leukotriene C4, key for intracrine signaling of endoplasmic reticulum (ER) stress, oxidative DNA damage and cell death. MGST2 trimer restricts catalysis to only one out of three active sites at a time, but the molecular basis is unknown. Here, we present crystal structures of human MGST2 combined with biochemical and computational evidence for a concerted mechanism, involving local unfolding coupled to global conformational changes that regulate catalysis. Furthermore, synchronized changes in the biconical central pore modulate the hydrophobicity and control solvent influx to optimize reaction conditions at the active site. These unique mechanistic insights pertain to other, structurally related, drug targets.


Asunto(s)
Glutatión Transferasa/química , Glutatión Transferasa/genética , Glutatión Transferasa/metabolismo , Sitios de Unión , Catálisis , Dominio Catalítico , Cristalografía por Rayos X , Retículo Endoplásmico/metabolismo , Humanos , Leucotrieno C4/metabolismo , Simulación de Dinámica Molecular , Mutagénesis Sitio-Dirigida , Estrés Oxidativo , Conformación Proteica
2.
Bioresour Technol ; 329: 124874, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33647605

RESUMEN

This study investigated on the co-pyrolysis of microalgae Chlorella vulgaris and high-density polyethylene (HDPE) waste mixtures which was performed with three types of catalysts, namely limestone (LS), HZSM-5 zeolite, and novel bi-functional LS/HZSM-5/LS. Kissinger-Kai (K-K) model-free method was coupled with Particle Swarm Optimization (PSO) model-fitting method using the thermogravimetric experimental data. A global sensitivity analysis was carried out using Latin Hypercube Sampling and rank transformation to assess the extent of impact of the input kinetic parameters on the output results. Furthermore, a thermodynamic analysis was performed to obtain parameters such as enthalpy change (ΔH), Gibb's free energy (ΔG), and entropy change (ΔS). The activation energy (EA) of the microalgae Chlorella vulgaris and HDPE binary mixture were found to be lower upon the addition of catalysts. Among the catalyst used, bi-functional LS/HZSM-5 catalyst exhibited the lowest EA (83.59 kJ/mol) and ΔH (78 kJ/mol) as compared to LS and HZSM-5 catalysts.


Asunto(s)
Chlorella vulgaris , Catálisis , Cinética , Plásticos , Pirólisis , Termogravimetría
3.
J Environ Manage ; 286: 112226, 2021 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-33677338

RESUMEN

Green-synthesized materials and solar concentration technology for advanced oxidation processes (AOPs) offer important opportunities in water remediation by giving value to clean, renewable and potentially low-cost resources. Here, Zinc Oxide (ZnO) nanostructures (NSs) were prepared via a green synthesis method based on garlic bulbs (Allium Sativum) extract (ZnO-Green), resulting in crystalline (wurtzite) nanorods (NRs). ZnO nanoparticles (NPs) were also chemically prepared through a standard co-precipitation (ZnO-Chem) for comparative solar photocatalytic (PC) studies. The green-synthesized ZnO NRs exhibited a favorable photocatalytic activity (PCA) in colloidal suspension for the methylene blue (MB) dye degradation upon exposure to concentrated sunlight. Comparison with the chemically synthesized ZnO results in almost equal degradations of 94% in optimal loading condition. To explore the possibility to use immobilized photocatalyst in heterogeneous condition, green-synthesized ZnO NRs coatings were fabricated and compared with a 135 nm thick ZnO thin film produced by pulsed laser deposition (PLD) (ZnO-PLD). PCA on MB degradation (120 min experiments) resulted in degradations of 69% and 73%, respectively, proving the feasibility of the immobilized photocatalyst approach. Finally, an economic analysis of the process shows that the combination of green-synthesis and concentrated sunlight significantly reduces costs, paving the way for large-scale photocatalytic wastewater remediation.


Asunto(s)
Óxido de Zinc , Catálisis , Azul de Metileno , Luz Solar , Aguas Residuales
4.
J Environ Manage ; 286: 112130, 2021 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-33684804

RESUMEN

Silver nanoparticles doped with FCNT-TiO2 heterogeneous catalyst was prepared via one-step chemical reduction process and their efficacy was tested for hydrogen production under solar simulator. Crystallinity, purity, optical properties, and morphologies of the catalysts were examined by X-Ray diffraction, Raman spectroscopy, UV-Visible diffuse reflectance spectra, and Transmission Electron Microscopy. The chemical states and interface interactions were studied by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The optimized catalyst showed 19.2 mmol g-1 h-1 of hydrogen production, which is 28.5 and 7 times higher than the pristine TiO2 nanoparticles and FCNT-TiO2 nanocomposite, respectively. The optimized catalyst showed stability up to 50 h under the solar simulator irradiation. The natural solar light irradiated catalyst showed ~2.2 times higher hydrogen production rate than the solar simulator irradiation. A plausible reaction mechanism of Ag NPs/FCNT-TiO2 photocatalyst was elucidated by investigating the beneficial co-catalytic role of Ag NPs and FCNTs for enhanced hydrogen production.


Asunto(s)
Nanopartículas del Metal , Plata , Catálisis , Hidrógeno , Luz , Titanio
5.
Food Chem ; 352: 129368, 2021 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-33667921

RESUMEN

A high-performance voltammetric methodology was developed to achieve ultra-sensitive detection of riboflavin, employing an electrode modified by graphene oxide-covered hollow MnO2 spheres nanocomposite with high catalytic activity, large surface area, and hierarchical layered structure. Under the optimal conditions, the current responses of the oxidation peak located at -0.39 V showed a good linear relationship versus the concentration of riboflavin in the range of 1.0 nM-4.0 µM in acetate buffer (pH 5.4). The limit of detection was determined as 0.26 nM. Moreover, the proposed electrode exhibited high reproducibility (relative standard deviation of 1.7%, n = 10) and excellent stability (97.6% sensitivity within two months), which has been successfully applied to the quantification of riboflavin in complicated food matrices, with results in good accordance with those obtained by chromatography as a reference method, indicating it is an effective sensing platform for ultra-sensitive determination of riboflavin in practical applications.


Asunto(s)
Electroquímica/instrumentación , Grafito/química , Compuestos de Manganeso/química , Óxidos/química , Riboflavina/análisis , Catálisis , Electrodos , Análisis de los Alimentos , Límite de Detección , Oxidación-Reducción , Reproducibilidad de los Resultados
6.
Molecules ; 26(4)2021 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-33669994

RESUMEN

In the present work, shape tailored Cu2O microparticles were synthesized by changing the nature of the reducing agent and studied subsequently. d-(+)-glucose, d-(+)-fructose, d-(+)xylose, d-(+)-galactose, and d-(+)-arabinose were chosen as reducing agents due to their different reducing abilities. The morpho-structural characteristics were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and diffuse reflectance spectroscopy (DRS), while their photocatalytic activity was evaluated by methyl orange degradation under visible light (120 min). The results show that the number of carbon atoms in the sugars affect the morphology and particle size (from 250 nm to 1.2 µm), and differences in their degree of crystallinity and photocatalytic activity were also found. The highest activity was observed when glucose was used as the reducing agent.


Asunto(s)
Cobre/química , Luz , Sustancias Reductoras/química , Azúcares/química , Catálisis , Tamaño de la Partícula , Procesos Fotoquímicos , Propiedades de Superficie
7.
Bioresour Technol ; 330: 124975, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33770733

RESUMEN

Valorization of biomass to olefin or aromatics harbours tremendous practical value due to growing concerns about sustainable production of chemicals. Herein, the olefin or aromatics yields of ex-situ catalytic pyrolysis of pine can be regulated by impregnating Sn on hollow-structured ZSM-5 (M-ZSM-5) and microporous ZSM-5 catalysts in fixed-bed reactor, respectively. Results showed that Sn/ZSM-5 catalyst simultaneously increased medium acidic sites and maintained strong acidic sites, which obtained the maximum carbon yield of aromatics (33.77%) due to enhanced cracking and deoxygenation reactions. In addition, Sn boosted alkylation between olefin and aromatics, generating more alkylbenzene. In contrast, Sn/M-ZSM-5 catalyst produced the highest olefins carbon yield (12.39%) because the reduction of strong acidic sites and microporous volume inhibited the olefin aromatization. Moreover, olefins were easier to desorb from Sn/M-ZSM-5 due to the enhanced mass transfer ability, which weakened the alkylation reactions. The synergistic effect harbours great significance to manipulate the distribution of products.


Asunto(s)
Alquenos , Pirólisis , Biomasa , Catálisis , Estaño
8.
Science ; 371(6536): 1338-1345, 2021 03 26.
Artículo en Inglés | MEDLINE | ID: mdl-33766881

RESUMEN

Dearomative cycloaddition reactions represent an ideal means of converting flat arenes into three-dimensional architectures of increasing interest in medicinal chemistry. Quinolines, isoquinolines, and quinazolines, despite containing latent diene and alkene subunits, are scarcely applied in cycloaddition reactions because of the inherent low reactivity of aromatic systems and selectivity challenges. Here, we disclose an energy transfer-mediated, highly regio- and diastereoselective intermolecular [4 + 2] dearomative cycloaddition reaction of these bicyclic azaarenes with a plethora of electronically diverse alkenes. This approach bypasses the general reactivity and selectivity issues, thereby providing various bridged polycycles that previously have been inaccessible or required elaborate synthetic efforts. Computational studies with density functional theory elucidate the mechanism and origins of the observed regio- and diastereoselectivities.


Asunto(s)
Alquenos/química , Reacción de Cicloadición , Hidrocarburos Aromáticos/química , Catálisis , Transferencia de Energía , Estructura Molecular , Quinolinas/química , Estereoisomerismo
9.
Nat Commun ; 12(1): 1898, 2021 03 26.
Artículo en Inglés | MEDLINE | ID: mdl-33772017

RESUMEN

Triplet-triplet annihilation upconversion nanoparticles have attracted considerable interest due to their promises in organic chemistry, solar energy harvesting and several biological applications. However, triplet-triplet annihilation upconversion in aqueous solutions is challenging due to sensitivity to oxygen, hindering its biological applications under ambient atmosphere. Herein, we report a simple enzymatic strategy to overcome oxygen-induced triplet-triplet annihilation upconversion quenching. This strategy stems from a glucose oxidase catalyzed glucose oxidation reaction, which enables rapid oxygen depletion to turn on upconversion in the aqueous solution. Furthermore, self-standing upconversion biological sensors of such nanoparticles are developed to detect glucose and measure the activity of enzymes related to glucose metabolism in a highly specific, sensitive and background-free manner. This study not only overcomes the key roadblock for applications of triplet-triplet annihilation upconversion nanoparticles in aqueous solutions, it also establishes the proof-of-concept to develop triplet-triplet annihilation upconversion nanoparticles as background free self-standing biological sensors.


Asunto(s)
Glucosa Oxidasa/metabolismo , Glucosa/metabolismo , Nanopartículas/química , Oxígeno/química , Algoritmos , Catálisis/efectos de la radiación , Humanos , Luz , Modelos Químicos , Estructura Molecular , Nanopartículas/efectos de la radiación , Oxidación-Reducción/efectos de la radiación , Oxígeno/metabolismo , Espectrometría de Fluorescencia , Agua/química
10.
Molecules ; 26(4)2021 Feb 22.
Artículo en Inglés | MEDLINE | ID: mdl-33671544

RESUMEN

Phospha-Michael addition, which is the addition reaction of a phosphorus-based nucleophile to an acceptor-substituted unsaturated bond, certainly represents one of the most versatile and powerful tools for the formation of P-C bonds, since many different electrophiles and P nucleophiles can be combined with each other. This offers the possibility to access many diversely functionalized products. In this work, two kinds of basic pyridine-based organo-catalysts were used to efficiently catalyze phospha-Michael addition reactions, the 4-N,N-dimethylaminopyridinium saccharinate (DMAP·Hsac) salt and a fluorous long-chained pyridine (4-Rf-CH2OCH2-py, where Rf = C11F23). These catalysts have been synthesized and characterized by Lu's group. The phospha-Michael addition of diisopropyl, dimethyl or triethyl phosphites to α, ß-unsaturated malonates in the presence of those catalysts showed very good reactivity with high yield at 80-100 °C in 1-4.5 h with high catalytic recovery and reusability. With regard to significant catalytic recovery, sometimes more than eight cycles were observed for DMAP·Hsac adduct by using non-polar solvents (e.g., ether) to precipitate out the catalyst. In the case of the fluorous long-chained pyridine, the thermomorphic method was used to efficiently recover the catalyst for eight cycles in all the reactions. Thus, the easy separation of the catalysts from the products revealed the outstanding efficacy of our systems. To our knowledge, these are good examples of the application of recoverable organo-catalysts to the DMAP·Hsac adduct by using non-polar solvent and a fluorous long-chained pyridine under the thermomorphic mode in phospha-Michael addition reactions.


Asunto(s)
Malonatos/química , Metilaminas/química , Organofosfonatos/química , Compuestos Organofosforados/síntesis química , Fosfitos/química , Piridinas/química , Sacarina/química , Catálisis , Estructura Molecular , Compuestos Organofosforados/química , Sales (Química)/química
11.
Molecules ; 26(4)2021 Feb 23.
Artículo en Inglés | MEDLINE | ID: mdl-33672361

RESUMEN

The purpose of this review is to summarize the importance of microwave (MW) irradiation as a kind of catalyst in organophosphorus chemistry. Slow or reluctant reactions, such as the Diels-Alder cycloaddition or an inverse-Wittig type reaction, may be performed efficiently under MW irradiation. The direct esterification of phosphinic and phosphonic acids, which is practically impossible on conventional heating, may be realized under MW conditions. Ionic liquid additives may promote further esterifications. The opposite reaction, the hydrolysis of P-esters, has also relevance among the MW-assisted transformations. A typical case is when the catalysts are substituted by MWs, which is exemplified by the reduction of phosphine oxides, and by the Kabachnik-Fields condensation affording α-aminophosphonic derivatives. Finally, the Hirao P-C coupling reaction may serve as an example, when the catalyst may be simplified under MW conditions. All of the examples discussed fulfill the expectations of green chemistry.


Asunto(s)
Líquidos Iónicos/química , Microondas , Compuestos Organofosforados/química , Catálisis , Estructura Molecular , Compuestos Organofosforados/síntesis química
12.
Molecules ; 26(4)2021 Feb 20.
Artículo en Inglés | MEDLINE | ID: mdl-33672487

RESUMEN

Recently, N-substituted anilines have been the object of increasing research interest in the field of organic chemistry due to their role as key intermediates for the synthesis of important compounds such as polymers, dyes, drugs, agrochemicals and pharmaceutical products. Among the various methods reported in literature for the formation of C-N bonds to access secondary anilines, the one-pot reductive amination of aldehydes with nitroarenes is the most interesting procedure, because it allows to obtain diverse N-substituted aryl amines by simple reduction of nitro compounds followed by condensation with aldehydes and subsequent reduction of the imine intermediates. These kinds of tandem reactions are generally catalyzed by transition metal-based catalysts, mainly potentially reusable metal nanoparticles. The rapid growth in the last years in the field of metal-based heterogeneous catalysts for the one-pot reductive amination of aldehydes with nitroarenes demands for a review on the state of the art with a special emphasis on the different kinds of metals used as catalysts and their recyclability features.


Asunto(s)
Aldehídos/química , Compuestos de Anilina/síntesis química , Metales Pesados/química , Nitrocompuestos/química , Compuestos de Anilina/química , Catálisis , Estructura Molecular
13.
Molecules ; 26(4)2021 Feb 19.
Artículo en Inglés | MEDLINE | ID: mdl-33669560

RESUMEN

The production of cyclic carbonates from CO2 cycloaddition to epoxides, using the C-scorpionate iron(II) complex [FeCl2{κ3-HC(pz)3}] (pz = 1H-pyrazol-1-yl) as a catalyst, is achieved in excellent yields (up to 98%) in a tailor-made ionic liquid (IL) medium under mild conditions (80 °C; 1-8 bar). A favorable synergistic catalytic effect was found in the [FeCl2{κ3-HC(pz)3}]/IL system. Notably, in addition to exhibiting remarkable activity, the catalyst is stable during ten consecutive cycles, the first decrease (11%) on the cyclic carbonate yield being observed during the 11th cycle. The use of C-scorpionate complexes in ionic liquids to afford cyclic carbonates is presented herein for the first time.


Asunto(s)
Dióxido de Carbono/química , Carbonatos/química , Reacción de Cicloadición , Hierro/química , Catálisis , Compuestos Epoxi/química , Líquidos Iónicos/química , Cinética , Espectrofotometría Infrarroja , Temperatura
14.
Molecules ; 26(4)2021 Feb 19.
Artículo en Inglés | MEDLINE | ID: mdl-33669746

RESUMEN

The new coordination polymers (CPs) [Zn(µ-1κO1:1κO2-L)(H2O)2]n·n(H2O) (1) and [Cd(µ4-1κO1O2:2κN:3,4κO3-L)(H2O)]n·n(H2O) (2) are reported, being prepared by the solvothermal reactions of 5-{(pyren-4-ylmethyl)amino}isophthalic acid (H2L) with Zn(NO3)2.6H2O or Cd(NO3)2.4H2O, respectively. They were synthesized in a basic ethanolic medium or a DMF:H2O mixture, respectively. These compounds were characterized by single-crystal X-ray diffraction, FTIR spectroscopy, thermogravimetric and elemental analysis. The single-crystal X-ray diffraction analysis revealed that compound 1 is a one dimensional linear coordination polymer, whereas 2 presents a two dimensional network. In both compounds, the coordinating ligand (L2-) is twisted due to the rotation of the pyrene ring around the CH2-NH bond. In compound 1, the Zn(II) metal ion has a tetrahedral geometry, whereas, in 2, the dinuclear [Cd2(COO)2] moiety acts as a secondary building unit and the Cd(II) ion possesses a distorted octahedral geometry. Recently, several CPs have been explored for the cyanosilylation reaction under conventional conditions, but microwave-assisted cyanosilylation of aldehydes catalyzed by CPs has not yet been well studied. Thus, we have tested the solvent-free microwave-assisted cyanosilylation reactions of different aldehydes, with trimethylsilyl cyanide, using our synthesized compounds, which behave as highly active heterogeneous catalysts. The coordination polymer 1 is more effective than 2, conceivably due to the higher Lewis acidity of the Zn(II) than the Cd(II) center and to a higher accessibility of the metal centers in the former framework. We have also checked the heterogeneity and recyclability of these coordination polymers, showing that they remain active at least after four recyclings.


Asunto(s)
Aldehídos/química , Cianuros/química , Microondas , Polímeros/química , Pirenos/química , Compuestos de Trimetilsililo/química , Catálisis , Enlace de Hidrógeno , Ligandos , Modelos Moleculares , Conformación Molecular , Polímeros/síntesis química , Solventes , Termogravimetría
15.
Water Sci Technol ; 83(5): 993-1004, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33724931

RESUMEN

Three photocatalysts (CdS, ZnFe2O4, and NiFe2O4) were synthesized and their ability to photodegrade methylene blue (MB) was evaluated. MB was degraded by both spinel photocatalysts under visible light at room temperature, although their efficacy was less than that for CdS. The photocatalytic efficacies of NiFe2O4 were observed to be much greater than that for ZnFe2O4. All the synthesized nanoparticles absorbed visible light, while CdS had a larger absorption range within the visible light spectra and the most porous surface. Photo-deactivation was observed during the study, which could be due to the chemical adsorption of the degraded products on the catalyst surface. The factors that affected MB removal efficacy include the absorption range of photocatalysts, initial MB concentrations, amount of photocatalysts added, and photoreactor conditions. Life cycle analysis was used to compare the preparation methods of the photocatalysts in terms of energy consumption and environmental impact. The results showed that the hydrothermal method for NiFe2O4 preparation was less energy-intensive than the sol-gel method for CdS and ZnFe2O4 as the hydrothermal method is effective over a wider range of temperatures in aqueous media. Also, as ZnFe2O4, and NiFe2O4 have lower environmental impacts than CdS both show promise as photocatalysts.


Asunto(s)
Luz , Nanopartículas , Catálisis , Ambiente , Azul de Metileno
16.
Water Sci Technol ; 83(5): 1072-1084, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33724937

RESUMEN

A novel TiO2 nanoparticle was prepared through green synthesis using Calotropis gigantea (CG) leaf extract. Morphological analysis showed dispersed spherical CG-TiO2 nanoparticles with an average size of 42 nm. The prepared catalyst was used for the degradation of metformin (a widely used diabetic medicine) by solar photocatalysis. A three-factor central composite design (CCD) was used to explore the effect of independent variables, i.e., pH 3-7, metformin concentration 1-10 mg/L, and catalyst (CG-TiO2) dosage 0.5-2.0 g/L. A maximum metformin degradation of 96.7% was observed under optimum conditions i.e., pH = 9.7, initial metformin concentration = 9.7 mg/L and catalyst dosage = 0.7 g/L, with ∼86% mineralization efficiency. A quadratic model with an error <±5% was developed to predict the metformin degradation and the rate of degradation under the optimum conditions followed pseudo-first-order kinetics (k = 0.014/min). CG-TiO2 exhibited higher metformin degradation efficiency (96.7%) compared to P-25 (23.9%) at optimum conditions. The recyclability study indicated effective reuse of the catalyst for up to three cycles. The proposed metformin degradation route is hydroxyl radical (•OH) generation on the CG-TiO2 surface, transfer of •OH to the aqueous phase from CG-TiO2 and subsequent oxidation of metformin in the aqueous phase.


Asunto(s)
Calotropis , Metformina , Catálisis , Extractos Vegetales , Titanio
17.
Water Sci Technol ; 83(5): 1242-1249, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33724950

RESUMEN

Recently, the utilization of wastes, recovery of high value-added products from waste, and their use as raw materials in other industries with the logic of industrial symbiosis has become an important issue. In this study, removal efficiency of Reactive Orange 16 (RO16) dye from aqueous solution was studied using TiO2 catalyst recycled from an industrial waste effluent. The recycling of TiO2 waste from a paints manufacturing industry was carried out by sintering the TiO2-containing waste. The catalyst usability of TiO2-containing powder was then investigated in the removal of RO16 dye by photocatalytic oxidation process. In photocatalytic oxidation studies, TiO2/UV and TiO2/UV/H2O2 processes were investigated, where the effect of annealing temperature, the effect of H2O2 concentration, and the adsorption and photocatalytic effects on RO16 dye removal were studied. The results showed that 100% RO16 removal was obtained for the 10 mg/L initial RO16 concentration using the TiO2 (1 g/L)/UV process. At high initial RO16 concentration (50 mg/L), 100% RO16 removal was achieved by adding 10 mM H2O2.


Asunto(s)
Peróxido de Hidrógeno , Purificación del Agua , Catálisis , Titanio , Aguas Residuales
18.
J Environ Manage ; 285: 112155, 2021 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-33652186

RESUMEN

Fenton reaction is an oxidation process of interest in wastewater treatment because of its ability to degrade organic compounds. Iron-based magnetic particles can be a very useful catalyst when using heterogeneous Fenton process. The major problem of this heterogeneous process is the saturation of the Fe 3+ on the surface, which limits the process. In this study, the possibility of using magnetite particles as a substrate is presented, increasing its degradation efficiency by Fenton reaction through a regeneration process that achieves the electronic reduction of its surface using reducing agents. The results indicate that the regeneration process is quite effective, increasing the efficiency of the degradation of Methylene Blue up to 99%. The concentration of magnetite is the most influential factor in the efficiency of the reaction, while the regeneration time and the concentration of reducing agent do not significantly affect the results considering the range used. The presence of mechanical stirring may adversely affect the reaction in the long term. Increasing the oxidant agent concentration reduces the initial speed of the reaction but not the long-term efficiency. The use of hydrazine in this process allows the successive reuse of these particles maintaining a high percentage of elimination of methylene blue, above 70% even after 10 uses, compared to an elimination below 20% for particles not regenerated after the second use and for particles regenerated with ascorbic acid after the eighth use.


Asunto(s)
Contaminantes Químicos del Agua , Purificación del Agua , Catálisis , Peróxido de Hidrógeno , Fenómenos Magnéticos , Oxidación-Reducción , Agua , Contaminantes Químicos del Agua/análisis
19.
Waste Manag ; 125: 77-86, 2021 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-33677181

RESUMEN

Pyrolysis of furfural residue (FR) was performed at 450-850 °C by employing a fluidized bed pyrolyzer (FBP). Addition of Kaolin and Ca-bentonite to FR considerably increased the condensate yields. The highest condensate yield (24.96 wt%) was obtained at 650 °C when Ca-bentonite was added. Fourier transform infra-red (FTIR) spectrum of pyrolysis oil (PO) indicated that catalysts promoted generation of alkene, amine, sulfate, sulfonyl chloride and oxime during pyrolysis. Gas chromatography mass spectrometry (GC-MS) demonstrated that catalysts significantly increased the content of furfural and phenol in PO and the maximum phenol content (15.36%) was achieved in PO650-3 for CaO. The quite low relative proportion (RP) of ammonia nitrogen in liquid indicated that the dominant form of nitrogen in liquid was not ammonia nitrogen. CaO had the ability to reduce H2S release, indicating significant sulfur retention capacity. The maximum RP (99.29%) of chlorine in bio-char (BC) was observed with the addition of CaO, showing its strong chlorine retention capacity.


Asunto(s)
Furaldehído , Pirólisis , Biocombustibles/análisis , Catálisis , Gases , Calor
20.
Nat Commun ; 12(1): 1345, 2021 03 01.
Artículo en Inglés | MEDLINE | ID: mdl-33649319

RESUMEN

Drug therapy unavoidably brings toxic side effects and drug content-limited therapeutic efficacy although many nanocarriers have been developed to improve them to a certain extent. In this work, a concept of drug-free therapeutics is proposed and defined as a therapeutic methodology without the use of traditional toxic drugs, without the consumption of therapeutic agents during treatment but with the inexhaustible therapeutic capability to maximize the benefit of treatment, and a Z-scheme SnS1.68-WO2.41 nanocatalyst is developed to achieve near infrared (NIR)-photocatalytic generation of oxidative holes and hydrogen molecules for realizing combined hole/hydrogen therapy by the drug-free therapeutic strategy. Without the need of any drug and other therapeutic agent assistance, the nanocatalyst oxidizes/consumes intratumoral over-expressed glutathione (GSH) by holes and simultaneously generates hydrogen molecules in a lasting and controllable way under NIR irradiation. Mechanistically, generated hydrogen molecules and GSH consumption inhibit cancer cell energy and destroy intratumoral redox balance, respectively, to synergistically damage DNA and induce tumor cell apoptosis. High efficacy and biosafety of combined hole/hydrogen therapy of tumors are achieved by the nanocatalyst. The proposed catalysis-based drug-free therapeutic strategy breaks a pathway to realize high efficacy and low toxicity of cancer treatment.


Asunto(s)
Antineoplásicos/uso terapéutico , Neoplasias/tratamiento farmacológico , Neoplasias/radioterapia , Fototerapia , Animales , Catálisis/efectos de la radiación , Línea Celular Tumoral , Glutatión/química , Humanos , Hidrógeno/química , Rayos Infrarrojos , Antígeno Ki-67/metabolismo , Ratones , Nanopartículas/ultraestructura , Tamaño de la Partícula , Análisis Espectral , Carga Tumoral , Microambiente Tumoral
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