Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 9 de 9
Filtrar
Mais filtros








Base de dados
Intervalo de ano de publicação
1.
Wiad Lek ; 75(12): 2987-2993, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36723315

RESUMO

OBJECTIVE: The aim: To determine the dose dependence of the subchronic effect of acetamiprid on the body of rats based on the data of morphological studies of internal organs. PATIENTS AND METHODS: Materials and methods: The experiment was performed on Wistar Han rats, which were orally administered acetamiprid in doses of 6, 12 and 60 mg/kg for 13 weeks. During the experiment, clinical studies were carried out, the general condition of the animals, body weight were assessed. After necropsy, the absolute and relative weight of internal organs was determined, and morphological studies of the brain, liver, kidneys, and spleen were performed with using an Olympus BX 54 light microscope and an Olympus C-5050 ZOOM camera with software Olympus DP-Soft. The research results were subjected to statistical processing using the Microsoft Excel 2010 computer program package. RESULTS: Results: The most pronounced manifestations of the toxic effect of acetamiprid were observed at a dose of 60 mg/kg, which indicated its hepatotoxic and nephrotoxic effects, as well as neurotoxic effects with signs of irreversible neurocyte damage. CONCLUSION: Conclusions: Morphological studies showed a dose-dependent nature and degree of expressiveness of the toxic effect of acetamiprid. According to the totality and nature of the changes revealed in the conditions of the conducted subchronic experiment on rats, no observed adverse effect level (NOAEL) was determined at the level of 12 mg/kg, no observed effect level (NOEL) - 6 mg/kg.


Assuntos
Fígado , Ratos , Animais , Ratos Wistar , Neonicotinoides/toxicidade , Nível de Efeito Adverso não Observado
2.
Chem Commun (Camb) ; 53(73): 10192-10195, 2017 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-28856367

RESUMO

Triazoles have been successfully used as building blocks to create "fully organic" ILs featuring on both sides organic ions, i.e., 1,2,3- or 1,2,4-triazolide anions and 1,2,4-triazolium or imidazolium cations. Glass transition temperatures, densities and viscosities of these ILs were determined. Their electrochemical and thermal stability, and also conductivity, are higher than those for known ILs.

3.
ACS Appl Mater Interfaces ; 9(27): 22941-22949, 2017 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-28609616

RESUMO

Photocatalytically active composites comprising potassium poly(heptazine imide) (PHIK) and a Ti-based metal-organic framework (MOF, MIL-125-NH2) are prepared in situ by simply dispersing both materials in water. The driving forces of composite formation are the electrostatic interactions between the solids and the diffusion of potassium ions from PHIK to MIL-125-NH2. This mechanism implies that other composites of poly(heptazine imide) salts and different MOFs bearing positive surface charge can potentially be obtained in a similar fashion. The suggested strategy thus opens a new avenue for the facile synthesis of such materials. The composites are shown to have a superior photocatalytic activity in Rhodamine B degradation under blue light irradiation. The reaction rate is doubled compared to that of pure MOF compound and is 7 times higher than the activity of the pristine PHIK. The results of the electron paramagnetic resonance (EPR) investigations and the analysis of the electronic structures of the solids suggest the electron transfer from MIL-125-NH2 to PHIK in the composite. The possible pathways for the dye degradation and the rationalization of the increased activity of the composites are elaborated.

4.
Adv Mater ; 29(32)2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28632318

RESUMO

Cost-efficient, visible-light-driven hydrogen production from water is an attractive potential source of clean, sustainable fuel. Here, it is shown that thermal solid state reactions of traditional carbon nitride precursors (cyanamide, melamine) with NaCl, KCl, or CsCl are a cheap and straightforward way to prepare poly(heptazine imide) alkali metal salts, whose thermodynamic stability decreases upon the increase of the metal atom size. The chemical structure of the prepared salts is confirmed by the results of X-ray photoelectron and infrared spectroscopies, powder X-ray diffraction and electron microscopy studies, and, in the case of sodium poly(heptazine imide), additionally by atomic pair distribution function analysis and 2D powder X-ray diffraction pattern simulations. In contrast, reactions with LiCl yield thermodynamically stable poly(triazine imides). Owing to the metastability and high structural order, the obtained heptazine imide salts are found to be highly active photocatalysts in Rhodamine B and 4-chlorophenol degradation, and Pt-assisted sacrificial water reduction reactions under visible light irradiation. The measured hydrogen evolution rates are up to four times higher than those provided by a benchmark photocatalyst, mesoporous graphitic carbon nitride. Moreover, the products are able to photocatalytically reduce water with considerable reaction rates, even when glycerol is used as a sacrificial hole scavenger.

5.
Chem Asian J ; 12(13): 1517-1522, 2017 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-28199049

RESUMO

Highly crystalline potassium (heptazine imides) were prepared by the thermal condensation of substituted 1,2,4-triazoles in eutectic salt melts. These semiconducting salts are already known to be highly active photocatalysts, for example, for the visible-light-driven generation of hydrogen from water. Herein, we show that within the solid-state structure, potassium ions can be exchanged to other metal ions while the crystal habitus is essentially preserved.

6.
ACS Nano ; 10(3): 3166-75, 2016 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-26863408

RESUMO

Herein, we present an approach to create a hybrid between single-atom-dispersed silver and a carbon nitride polymer. Silver tricyanomethanide (AgTCM) is used as a reactive comonomer during templated carbon nitride synthesis to introduce both negative charges and silver atoms/ions to the system. The successful introduction of the extra electron density under the formation of a delocalized joint electronic system is proven by photoluminescence measurements, X-ray photoelectron spectroscopy investigations, and measurements of surface ζ-potential. At the same time, the principal structure of the carbon nitride network is not disturbed, as shown by solid-state nuclear magnetic resonance spectroscopy and electrochemical impedance spectroscopy analysis. The synthesis also results in an improvement of the visible light absorption and the development of higher surface area in the final products. The atom-dispersed AgTCM-doped carbon nitride shows an enhanced performance in the selective hydrogenation of alkynes in comparison with the performance of other conventional Ag-based materials prepared by spray deposition and impregnation-reduction methods, here exemplified with 1-hexyne.

7.
Angew Chem Int Ed Engl ; 54(38): 11265-9, 2015 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-26230282

RESUMO

We report the preparation and hydrogenation performance of a single-site palladium catalyst that was obtained by the anchoring of Pd atoms into the cavities of mesoporous polymeric graphitic carbon nitride. The characterization of the material confirmed the atomic dispersion of the palladium phase throughout the sample. The catalyst was applied for three-phase hydrogenations of alkynes and nitroarenes in a continuous-flow reactor, showing its high activity and product selectivity in comparison with benchmark catalysts based on nanoparticles. Density functional theory calculations provided fundamental insights into the material structure and attributed the high catalyst activity and selectivity to the facile hydrogen activation and hydrocarbon adsorption on atomically dispersed Pd sites.


Assuntos
Paládio/química , Catálise , Hidrogenação , Microscopia Eletrônica de Transmissão e Varredura
8.
Chemistry ; 21(30): 10805-11, 2015 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-26176645

RESUMO

Carbon nitrides with the increased surface areas (≈90 m(2) g(-1)) were prepared by the heat-treatment of melamine-[Al(NO3)3]⋅9 H2O complexes. Here, [Al(NO3)3]⋅9 H2O was successfully used as a "green template" and a hydrogen-bonding partner of melamine, simultaneously providing a distinct porosity and defined particle morphology for the resulting carbon nitrides. The influence of the solvent and precursors ratio on the stoichiometry of the complexes, as well as the morphology, optical properties, and photocatalytic activity of resulting products for Rhodamine B degradation and sacrificial hydrogen evolution were investigated. We also studied the temperature-induced transformations of the starting complex to access the reaction mechanism. The developed synthesis procedure results in a significantly increased photocatalytic activity (up to 20-fold) compared with that of the ground reference material.

9.
Macromol Rapid Commun ; 32(15): 1145-9, 2011 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-21710528

RESUMO

Virtually transparent films of Aeroxide TiO(2) P25 were fabricated via layer-by-layer assembly with sodium poly(styrene sulfonate). Nanoscale films are formed on model surfaces for characterization or inside of cylindrical reactors for investigating the catalytic properties. Films are fairly homogeneous and smooth over large areas and show different optical interference colors depending on film thickness. The application-relevant photocatalytic performance of such films toward on-flow degradation of hydrogen sulfide under UV-A irradiation was investigated. Scanning electron microscopy reveals a nanoporous structure allowing for the permeation of gas. Consequently, the catalytic efficiency of the films increases with increasing film thickness retaining a considerable activity of the corresponding nanoparticle powder. Scheme 1 depicts in a general way the functionalized reactor and the principle of the measurement.


Assuntos
Poluentes Atmosféricos/química , Eletrólitos/química , Sulfeto de Hidrogênio/química , Nanopartículas/química , Dióxido de Enxofre/química , Catálise , Processos Fotoquímicos , Raios Ultravioleta
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA