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1.
Chemosphere ; 267: 129243, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33338721

RESUMEN

Because of the abundance of transition metals, their enhanced electrochemical/chemical efficiency on par with the benchmark catalysts, long-term stability, etc., the expansion of transition metal/metal oxide-based electrocatalysts for oxygen evolution, urea oxidation reactions and 4-nitrophenol reduction becomes indispensable. In particular, the abundant availability along with improved electrochemical performance is crucial for fuel cell applications when it comes to large scale commercialization. In this work, we report the synthesis of a trimetallic metal-organic framework based on Ni, Co and Zn using BTC as a linker and the preparation of its metal oxide - carbon composites at different temperatures, 600, 700 and 800 °C (TM-MOF-600, TM-MOF-700, and TM-MOF-800) by carbonization under an inert atmosphere. The PXRD pattern of TM-MOF complemented well with the simulated XRD patterns of Co-Ni-BTC MOF as well as Zn-BTC MOF, whereas the PXRD pattern of the carbonized samples indicated the presence of three types of metal oxides i.e., CoO, NiO, and ZnO. TEM indicated spherical morphology of TM-MOF, upon calcination, an irregular agglomeration occurred and the average particle size was found to be 60-110 nm. The as-prepared TM-MOF and its carbon composites were tested for their electrocatalytic as well as catalytic activities towards oxygen evolution, urea oxidation and 4-nitrophenol reduction reactions. Electrochemical results indicate the better performance of TM-MOF-800 in both OER and UOR reactions with an onset potential of 1.66 V (OER) and 1.37 V (UOR) at a current density of 10 mA cm-2. The long-term stability of these catalysts under alkaline conditions indicates excellent stability. Besides, the urea electrolyzed products were analyzed by gas chromatography to get clear insights on the formed products. Catalytic reduction of 4-nitrophenol in the presence of excess NaBH4 showed excellent conversion to 4-amino phenol in short duration.


Asunto(s)
Carbono , Urea , Catálisis , Metales , Nitrofenoles
2.
Chemosphere ; 267: 129245, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33321274

RESUMEN

Phenolic compounds bisphenol A (BPA) and 4-nitrophenol (4-NP) are the prime water contaminants. As reported, these compounds are some of the highly hazardous ones to the human and living species. In this study, T-ZnO-rGO-PEI composite was synthesized employing hydrothermal method and the obtained composite samples were systematically characterized by FTIR, XPS, FE-SEM and HR-TEM studies. The FTIR, XPS analysis confirmed the successful surface modification of T-ZnO-rGO-PEI composite. The FE-SEM morphology confirmed the formation of ZnO (arm length about 2.5 µm) tetrapod structured in synthesized T-ZnO-rGO-PEI composite. The thickness of formed ZnO arm (0.44 µm) was increased after the polymer coating which confirmed the successful surface modification by PEI polymer. The HR-TEM images confirm the uniform coating of PEI polymer on T-ZnO-rGO surface. The catalytic activity and adsorption capacity of the synthesized T-ZnO-rGO-PEI composite was successfully explored using 4-nitrophenol and bisphenol-A as model pollutants .T-ZnO-rGO-PEI composite and found that 4-NP reduction reaction was completed within 10 min with the rate of 0.224 min-1. The BPA adsorption over T-ZnO-rGO-PEI exhibited high adsorption rate of 0.0210 min-1. In addition, the detailed 4-NP reduction and BPA adsorption mechanism was demonstrated. Hence the synthesized T-ZnO-rGO-PEI composite is a promising catalyst for the removal of micropollutants in aqueous medium.


Asunto(s)
Grafito , Óxido de Zinc , Adsorción , Catálisis , Color , Humanos
3.
Neurotox Res ; 2020 Nov 03.
Artículo en Inglés | MEDLINE | ID: mdl-33141427

RESUMEN

Cadmium (Cd) is a heavy metal of considerable toxicity, inducing a number of hazardous effects to humans and animals including neurotoxicity. This experiment was aimed to investigate the potential effect of kaempferol (KPF) against Cd-induced cortical injury. Thirty-two adult Sprague-Dawley rats were divided equally into four groups. The control rats intraperitoneally (i.p.) injected with physiological saline (0.9% NaCl), the cadmium chloride (CdCl2)-treated rats were i.p. injected with 4.5 mg/kg of CdCl2, the KPF-treated rats were orally gavaged with 50 mg/kg of KPF, and the KPF + CdCl2-treated rats were administered orally 50 mg/kg of KPF 120 min before receiving i.p. injection of 4.5 mg/kg CdCl2. CdCl2 exposure for 30 days led to the accumulation of Cd in the cortical tissue, accompanied by a reduction in the content of monoamines and acetylcholinesterase activity. Additionally, CdCl2 induced a state of oxidative stress as evidenced by the elevation of lipid peroxidation and nitrate/nitrite levels, while glutathione content and the activities of glutathione peroxidase, glutathione reductase, superoxide dismutase, and catalase were decreased. Moreover, CdCl2 mediated inflammatory events in the cortical tissue through increasing tumor necrosis factor-alpha and interleukin-1 beta levels and upregulating the expression of inducible nitric oxide synthase. Furthermore, pro-apoptotic proteins (Bax and caspase-3) were elevated, while Bcl-2, the anti-apoptotic protein, was decreased. Also, histological alterations were observed obviously following CdCl2. However, KPF pretreatment restored significantly the examined markers to be near the normal values. Hence, the obtained data provide evidences that KPF pretreatment has the protective effect to preserve the cortical tissues in CdCl2-exposed rats by restraining oxidative stress, inflammatory response, apoptosis, neurochemical modulation, and improving the histological changes.

4.
Sci Total Environ ; 723: 137969, 2020 Jun 25.
Artículo en Inglés | MEDLINE | ID: mdl-32392679

RESUMEN

Environmental and occupational exposure to heavy metals, including cadmium (Cd), is associated with extremely adverse impacts to living systems. Antioxidant agents are suggested to eliminate Cd intoxication. In this paper, we investigated the potential neuroprotective effect of protocatechuic acid (PCA) against Cd-induced neuronal damage in rats. Adult male Wistar rats were randomly divided into control, PCA (100 mg/kg)-treated, CdCl2 (6.5 mg/kg)-treated, and PCA and Cd treatment groups. Pre-treatment with PCA significantly reduced Cd concentrations and increased cortical acetylcholinesterase activity and brain derived neurotrophic factor. Additionally, PCA also prevented CdCl2-induced oxidative stress in the cortical tissue by preventing lipid peroxidation and the formation of nitric oxide (NO), and significantly enhancing antioxidant enzymes. Molecularly, PCA significantly up-regulated the antioxidant gene expression (Sod2, Cat, Gpx1, and Gsr) that was down-regulated by Cd. It should be noted that this effect was achieved by targeting the nuclear-related factor 2 (Nfe2l2) mRNA expression. PCA also prevented the Cd-induced inflammation by reducing the pro-inflammatory cytokines, including tumor necrosis factor-α and interleukin-1ß. Moreover, PCA supplementation relieved the Cd-induced neuronal death by increasing Bcl-2 and decreasing Bax and Cas-3 levels in the cortical tissue. The improvement of the cortical tissue histopathology by PCA confirmed the biochemical and molecular data. Collectively, our findings indicate that PCA can counteract Cd-induced cortical toxicity by enhancing the antioxidant defense system and suppressing inflammation and apoptosis.


Asunto(s)
Cadmio , Estrés Oxidativo , Animales , Antioxidantes , Apoptosis , Hidroxibenzoatos , Inflamación , Masculino , Ratas , Ratas Wistar
5.
Environ Pollut ; 168: 107-12, 2012 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-22609861

RESUMEN

There is growing concern over the potential detrimental impact of ionizing radiation on natural biota. The mechanistic cause-and-effect impact of ionizing radiation has yet to be characterized in any aquatic species. Adopting an integrated approach, including radiochemical analysis of environmental samples, we evaluate molecular responses to ionizing radiation in the marine mussel, Mytilus edulis. These responses included analyses of RAD51 mRNA expression, a gene involved in the repair of DNA double strand breaks, and induction of DNA strand breaks using the comet assay, in samples collected from a site impacted by low level ionizing radiation discharges. Based on activities of the radionuclides measured in sediment and mussel tissue at the discharge site, external and internal dose rates were low, at ca. 0.61 µGyh(-1) and significantly lower than the generic (all species) "no effect" dose rate of 10 uGyh(-1), yet DNA strand breakage and RAD51 mRNA expression were both altered.


Asunto(s)
Mytilus edulis/efectos de la radiación , Radiación Ionizante , Contaminantes Radiactivos del Agua/toxicidad , Animales , Ensayo Cometa , Daño del ADN , Relación Dosis-Respuesta en la Radiación , Sedimentos Geológicos/química , Mytilus edulis/genética , Mytilus edulis/metabolismo , ARN Mensajero/metabolismo , Recombinasa Rad51/genética , Recombinasa Rad51/metabolismo , Contaminantes Radiactivos del Agua/análisis , Contaminantes Radiactivos del Agua/metabolismo
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