scholarly journals Systematic Study of the Behavior of Different Metal and Metal-Containing Particles under the Microwave Irradiation and Transformation of Nanoscale and Microscale Morphology

Nanomaterials ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 19 ◽  
Author(s):  
Evgeniy Pentsak ◽  
Vera Cherepanova ◽  
Mikhail Sinayskiy ◽  
Andrey Samokhin ◽  
Valentine Ananikov
Keyword(s):  
Microwave Irradiation ◽  
Systematic Study ◽  
High Performance ◽  
Chemical Structure ◽  
Carbon Support ◽  
Carbon Surface ◽  
Catalytic Systems ◽  
Nanoscale Particles ◽  
Catalytic Materials ◽  
Solid Form

In recent years, the application of microwave (MW) irradiation has played an increasingly important role in the synthesis and development of high performance nanoscale catalytic systems. However, the interaction of microwave irradiation with solid catalytic materials and nanosized structures remains a poorly studied topic. In this paper we carried out a systematic study of changes in morphology under the influence of microwave irradiation on nanoscale particles of various metals and composite particles, including oxides, carbides, and neat metal systems. All systems were studied in the native solid form without a solvent added. Intensive absorption of microwave radiation was observed for many samples, which in turn resulted in strong heating of the samples and changes in their chemical structure and morphology. A comparison of two very popular catalytic materials—metal particles (M) and supported metal on carbon (M/C) systems—revealed a principal difference in their behavior under microwave irradiation. The presence of carbon support influences the heating mechanism; the interaction of substances with the support during the heating is largely determined by heat transfer from the carbon. Etching of the carbon surface, involving the formation of trenches and pits on the surface of the carbon support, were observed for various types of the investigated nanoparticles.

scholarly journals Towards High Efficacy of Pd-Au/C Catalyst for Tetrachloromethane Hydrodechlorination

Chemistry ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 338-359
Author(s):  
Magdalena Bonarowska ◽  
Zbigniew Kaszkur ◽  
Krzysztof Matus ◽  
Alicja Drelinkiewicz ◽  
Tomasz Szumełda ◽  
...  
Keyword(s):  
Microwave Irradiation ◽  
Gas Phase ◽  
Thermal Activation ◽  
Supported Catalysts ◽  
Carbon Support ◽  
Thermal Reduction ◽  
Microwave Oven ◽  
Optimal Conditions ◽  
Catalyst Activation ◽  
Critical Part

We present an efficient strategy for synthesising the PdAu catalysts with a homogeneous PdAu alloy phase for environmentally important hydrodechlorination of tetrachloromethane in the gas phase. The synthesis of carbon-supported catalysts involved two major steps: (i) incorporation of palladium and gold nanoparticles into carbon support and (ii) activation of the catalysts. The critical part of this work was to find the optimal conditions for both steps. Thus, the incorporation of the nanoparticles was carried out in two ways, by impregnation and direct redox reaction method using acetone solutions of metal precursor salts. The activation was performed either by a conventional thermal reduction in hydrogen or flash irradiation in a microwave oven. The homogeneity and structure of the PdAu alloy were found to depend on the catalyst activation method critically. In all cases, we observed better homogeneity for catalysts that were subject to microwave irradiation. Moreover, the flash microwave irradiation of prepared catalysts provided catalysts of better stability and selectivity towards the desired products (hydrocarbons) in the hydrodechlorination of tetrachloromethane as compared to the catalyst obtained by conventional thermal activation in hydrogen.

Direct Growth of Polyaniline Chains from Nitrogen Site of N-Doped Carbon Nanotubes for High Performance Supercapacitor

2014 ◽  
Vol 93 ◽  
pp. 164-167 ◽  
Author(s):  
Joon Won Lim ◽  
Atta Ul Haq ◽  
Sang Ouk Kim
Keyword(s):  
Carbon Nanotubes ◽  
High Performance ◽  
Chemical Structure ◽  
Carbon Materials ◽  
Graphitic Carbon ◽  
Polymer Grafting ◽  
Aniline Monomer ◽  
Defect Site ◽  
Direct Growth ◽  
Grafting From

Polymer grafting from graphitic carbon materials has been explored for several decades. Currently existing methods mostly employ harsh chemical treatment to generate defect site in graphitic carbon plane, which are used as active site for polymerization of precursors. Unfortunately, the treatment cause serious degradation of chemical structure and material properties. Here, we present a straightforward route for growth of polyaniline chain from nitrogen (N)-sites of carbon nanotubes. N site in the CNT wall initiates the polymerization of aniline monomer, which generates seamless hybrids composed of polyaniline directly grafted onto the CNT walls. The synthesized hybrids show excellent synergistic electrochemical performance, and are employed for electrodes of pseudo-capacitor. This approach offers an efficient way to obtain hybrid system consisting of conducting polymers directly grafted from graphitic dopant sites.

The Chemical Structure Responsible for the Deactivating Effect of Compounds Which Protect Rubber from Deterioration by Oxygen

1951 ◽  
Vol 24 (3) ◽  
pp. 638-639
Author(s):  
Jean Le Bras ◽  
Jacques Le Foll
Keyword(s):  
Nitrogen Atom ◽  
Systematic Study ◽  
Chemical Structure ◽  
Thiol Group ◽  
Vulcanized Rubber ◽  
Thiol Form

Abstract One of the present authors has already offered evidence which indicates the existence of a deactivating effect, whereby vulcanized rubber is protected against deterioration by oxygen. This effect is evident with such compounds as mercaptobenzimidazole (I), mercaptobenzoxazole, and ethylene-bis (N,N′-phenylthiourea) (II), and the phenomenon seems to be connected in some way with the presence in the molecule of a thiol group united to a nitrogen atom under such conditions that the possible tautomerism between the thion and thiol forms (III) is probably displaced toward the thiol form. We have completed these earlier experiments by a more systematic study, which has included an examination of the influence of cyclization, the nature of the ring, and hetero atoms.

scholarly journals METHYL 10-EPI-PHEOPHORBIDE A FROM MCF-7 CELLS ACTIVE LAYER OF THE INDONESIAN FICUS DELTOIDEA JACK LEAVES

2017 ◽  
Vol 9 (8) ◽  
pp. 183 ◽  
Author(s):  
Anggia Murni ◽  
Novriyandi Hanif ◽  
Masaki Kita ◽  
Latifah K. Darusman
Keyword(s):  
Active Layer ◽  
Column Chromatography ◽  
Breast Tumor ◽  
High Performance ◽  
Chemical Structure ◽  
High Resolution Mass Spectrometry ◽  
Assay Method ◽  
Pheophorbide A ◽  
Ficus Deltoidea ◽  
Mcf 7

Objective: To isolate and elucidate a cytotoxic principle against breast tumor MCF-7 cells of the Indonesian terrestrial plant Ficus deltoidea Jack leaves.Methods: F. deltoidea leaves collected at National Park of mount Gede-Pangrango, Indonesia have been subjected to chemical and biological work. F. deltoidea leaves were extracted with 96% aqueous ethanol (EtOH) and was then partitioned into three layers n-hexane, dichloromethane (CH2Cl2), and n-butanol (n-BuOH). All layers were checked for their activity against breast tumor MCF-7 cells using MTT assay method. A portion of the most active layer was purified using open column chromatography to give fraction that has toxicity against zebra fish embryos. Based on the assay-guided isolation, compound 1 was isolated. The chemical structure of 1 was elucidated using nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS) data as well as comparing data with literature.Results: The CH2Cl2 layer of F. deltoidea leaves was found to inhibit breast tumor MCF-7 cells with IC50 10 µg/ml which was the most toxic among the layers. A portion of the most active layer was purified using open column chromatography to give 7 fractions. The fraction 5 showed toxicity against zebrafish embryos (LC50 35 µg/ml, 48 hpf). This fraction was purified using high performance liquid chromatography (HPLC) octadecylsilyl (ODS) column with gradient elution 70% aqueous acetonitrile (MeCN) to 100% MeCN (linear gradient) for 40 min with UV detection at 254 nm (tR = 30.99 min) to give compound 1. The chemical structure of 1 was revealed as a chlorin-type compound named methyl 10-epi-pheophorbide A.Conclusion: Methyl 10-epi-pheophorbide A was isolated for the first time from the active fraction of the Indonesian F. deltoidea leaves or tabat barito. The chemical structure including absolute stereo chemistry was elucidated using NMR and HRMS data as well as by comparison with the literature values. The 13C NMR data has been added to complete the previous report.

Synthesis and Characterization of Fluorinated Alkyl Substituted Disiloxane

2014 ◽  
Vol 529 ◽  
pp. 13-15
Author(s):  
Qing Chuan Xi ◽  
Ke Cao ◽  
Ya Wen Huang ◽  
Guan Jun Chang ◽  
Jun Xiao Yang
Keyword(s):  
High Performance ◽  
Chemical Structure ◽  
Rust Resistance ◽  
Condensation Reaction ◽  
Synthesis And Characterization ◽  
Silicon Oil ◽  
Temperature Performance ◽  
Diffusion Pump ◽  
Measurement Results

Alkyl substituted disiloxanes demonstrated promising applications as high performance hydraulic oil, diffusion pump oil, etc. In this study, fluorinated alkyl substituted disiloxane was synthesized via Grignard reaction followed by condensation reaction. Its chemical structure was verified by FTIR and NMR. Measurement results showed that this silicon oil exhibited good high temperature performance, oxidation resistance and rust resistance.

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