排序方式: 共有44条查询结果,搜索用时 171 毫秒
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M. Abdallah Hatem M. Altass B. A. AL Jahdaly M. M. Salem 《Green Chemistry Letters and Reviews》2018,11(3):189-196
The inhibiting impact of natural aqueous extracts of some plants such as curcumin, parsley and cassia bark extracts for the corrosion of carbon steel (C-steel) in 0.5 M H2SO4 solution was inspected utilizing some techniques such as galvanostatic and potentiodynamic anodic polarization and weight loss measurements. Outcomes indicated that the percentage inhibition efficiency increases with increasing the concentration of the extract due to its horizontal adsorption on the C-steel surface. The process of adsorption is followed by the Temkin isotherm. These natural extracts acted as pitting corrosion inhibitors by shifting the pitting potential to more noble values. The sequence of inhibition efficiency of the natural extracts decreases in the following order: cassia bark extract > parsley extract > curcumin extract. This arrangement is related to the molecular size of the major components of the three natural extracts used. 相似文献
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Co islands grown on Cu(111) with a stacking fault at the interface present a conductance in the empty electronic states larger than the Co islands that follow the stacking sequence of the Cu substrate. Electrons can be more easily injected into these faulted interfaces, providing a way to enhance transmission in future spintronic devices. The electronic states associated with the stacking fault are visualized by tunneling spectroscopy, and its origin is identified by band structure calculations. 相似文献
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Influence of Support Type and Metal Loading in Methane Decomposition over Iron Catalyst for Hydrogen Production
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Ahmed A. Ibrahim Ahmed S. Al‐Fatesh Wasim U. Khan Mostafa A. Soliman Raja L. AL Otaibi Anis H. Fakeeha 《中国化学会会志》2015,62(7):592-599
Natural gas resources, stimulate the method of catalytic methane decomposition. Hydrogen is a superb energy carrier and integral component of the present energy systems, while carbon nanotubes exhibit remarkable chemical and physical properties. The reaction was run at 700 °C in a fixed bed reactor. Catalyst calcination and reduction were done at 500 °C. MgO, TiO2 and Al2O3 supported catalysts were prepared using a co‐precipitation method. Catalysts of different iron loadings were characterized with BET, TGA, XRD, H2‐TPR and TEM. The catalyst characterization revealed the formation of multi‐walled nanotubes. Alternatively, time on stream tests of supported catalyst at 700 °C revealed the relative profiles of methane conversions increased as the %Fe loading was increased. Higher %Fe loadings decreased surface area of the catalyst. Iron catalyst supported with Al2O3 exhibited somewhat higher catalytic activity compared with MgO and TiO2 supported catalysts when above 35% Fe loading was used. CH4 conversion of 69% was obtained utilizing 60% Fe/Al2O3 catalyst. Alternatively, Fe/MgO catalysts gave the highest initial conversions when iron loading below 30% was employed. Indeed, catalysts with 15% Fe/MgO gave 63% conversion and good stability for 1 h time on stream. Inappropriateness of Fe/TiO2 catalysts in the catalytic methane decomposition was observed. 相似文献
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Ultra high performance liquid chromatography with mass spectrometry method for the simultaneous determination of phenolic constituents in honey from various floral sources using multiwalled carbon nanotubes as extraction sorbents
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Saikh Mohammad Wabaidur Yacine Badjah Hadj Ahmed Munir Saeed Obbed Nasser Mohamed AL‐Harbi Turki Mohammad AL‐Turki 《Journal of separation science》2015,38(15):2597-2606
An ultra high performance liquid chromatography with mass spectrometry method has been developed for the simultaneous separation, identification and determination of 22 phenolic constituents in honey from various floral sources from Yemen. Solid‐phase extraction was used for extraction of the target phenolic constituents from honey samples, while multiwalled carbon nanotubes were used as solid‐phase adsorbent. The chromatographic separation of all phenolic constituents was performed on a BEH C18 column using a linear gradient elution with a binary mobile phase mixture of aqueous 0.1% formic acid and methanol. The quantitation was carried out in selected ion reaction monitoring acquisition mode. The total amount of phenolic acids, flavonoids and other phenols in each analyzed honey was found in the range of 338–3312, 122–5482 and 2.4–1342 μg/100 g of honey, respectively. 4‐Hydroxybenzoic acid was found to be the major phenolic acid. The main detected flavonoid was chrysin, while cinnamic acid was found to be the major other phenol compound. The regeneration of solid phase adsorbent to be reused and recovery results confirm that the proposed method could be potentially used for the routine analysis of phenolic constituents in honey extract. 相似文献
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Functionalized nanoparticles based solid‐phase membrane micro‐tip extraction and high‐performance liquid chromatography analyses of vitamin B complex in human plasma
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Imran Ali Umma Kulsum Zeid A. AL‐Othman Abdulrahman Alwarthan Kishwar Saleem 《Journal of separation science》2016,39(14):2678-2688
Iron nanoparticles were prepared by a green method following functionalization using 1‐butyl‐3‐methylimidazolium bromide. 1‐Butyl‐3‐methylimidazole iron nanoparticles were characterized using FTIR spectroscopy, energy dispersive X‐ray fluorescence, X‐ray diffraction, scanning electron microscopy and transmission electron microscopy. The nanoparticles were used in solid‐phase membrane micro‐tip extraction to separate vitamin B complex from plasma before high‐performance liquid chromatography. The optimum conditions obtained were sorbent (15 mg), agitation time (30 min), pH (9.0), desorbing solvent [water (5 mL) + methanol (5 mL) + sodium hydroxide (0.1 N) + acetic acid (d = 1.05 kg/L, pH 5.5), desorbing volume (10 mL) and desorption time (30 min). The percentage recoveries of all the eight vitamin B complex were from 60 to 83%. A high‐performance liquid chromatography method was developed using a PhE column (250 × 4.6 mm, 5.0 μm) and water/acetonitrile (95:5, v/v; pH 4.0 with 0.1% formic acid) mobile phase. The flow rate was 1.0 mL/min with detection at 270 and 210 nm. The values of the capacity, separation and resolution factor were 0.57–39.47, 1.12–6.00 and 1.84–26.26, respectively. The developed sample preparation and chromatographic methods were fast, selective, inexpensive, economic and reproducible. The developed method can be applied for analyzing these drugs in biological and environmental matrices. 相似文献
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While bimetallic nanoparticles (NPs) offer greater tunability of their catalytic performance than their monometallic counterparts, their detailed mechanistic characterizations are still of a great challenging prospect, particularly at nanoscale. In this paper, we describe a unique (195)Pt nuclear magnetic resonance (NMR) based in situ technique that in principle enables us to access local elemental composition and electronic information across the dimension of the Pt-based NPs with decent spatial resolution. When combined with electrochemical analysis, it opens a way to correlate the local elemental composition and electronic properties with the catalytic activity of the bimetallic NPs. Specifically, from the (195)Pt NMR analysis we concluded that (1) for the PtRu/carbon nanofibers, Ru segregates at the surface while Pt does so inside the NPs; (2) alloying Ru substantially reduces the E(F) local density of states (LDOS) at the Pt atoms; (3) the larger variation in s-like E(F) LDOS at the surface region of the PtRu/graphite nanofibers may imply a higher diversity of catalytic sites available for reactions, therefore explains the observed higher reactivity in methanol electro-oxidation. 相似文献
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Saeid Abbasbandy Elyas Shivanian Khalid Hammood AL‐Jizani 《Numerical Methods for Partial Differential Equations》2021,37(1):462-478
In this study, we develop an approximate formulation for two‐dimensional nonlinear Sobolev problems by focusing on pseudospectral meshless radial point interpolation (PSMRPI) which is a kind of locally applied radial basis function interpolation and truthfully a meshless approach. In the PSMRPI method, the nodal points do not need to be regularly distributed and can even be quite arbitrary. It is easy to have high order derivatives of unknowns in terms of the values at nodal points by constructing operational matrices. The convergence and stability of the technique in some sense are studied via some examples to show the validity and trustworthiness of the PSMRPI technique. 相似文献
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