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281.
Jaime Retuert Alicia Nuez Francisco Martínez Mehrdad Yazdani-Pedram 《Macromolecular rapid communications》1997,18(2):163-167
This work reports the synthesis of a novel polymeric organic-inorganic hybrid. The inorganic component is a silica network obtained by controlled hydrolysis of tetraethyl orthosilicate via sol-gel process and the organic counterpart is partially deacetylated chitin (CHI). The resulting polymer hybrids were homogeneous transparent film forming glassy materials being compatible through a wide composition range. Simultaneous thermal analysis of a CHI/silica 1:1 mixture confirms the intermolecular complex formation between organic and inorganic polymers. 相似文献
282.
Fateme Hasanli Manochehr Bahmaei Sirwan Mohammadiazar Amir Abdollah Mehrdad Sharif 《Journal of separation science》2019,42(19):3110-3118
A novel and porous solid‐phase microextraction fiber was prepared by quick and simple galvanic displacement reaction and applied to the determination of some polycyclic aromatic hydrocarbons in sunflower oil. The parameters affecting the porosity and thickness of the fiber, and parameters affecting the extraction efficiency, including the extraction time, temperature, and ionic strength, were investigated and optimized. The morphology of prepared fiber was characterized by optical and scanning electron microscopy and thermal and chemical stabilities of the fiber were studied. Under the optimum conditions, the limits of detection ranged between 0.1 ng/mL for pyrene to 1.2 ng/mL for anthracene, and LOQ ranged between 0.3 ng/mL for pyrene to 3.6 ng/mL for anthracene. The relative standard deviations, including repeatability (within fibers) and reproducibility (between fibers), varied between 3.2–8.9 and 5.6–9.8%, respectively. 相似文献
283.
Support effects on the chemical property and catalytic activity of Co-Mo HDS catalyst in sulfur recovery 总被引:2,自引:0,他引:2
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Ali Nakhaei Pour Ali Morad Rashidi Kherolah Jafari Jozani Ali Mohajeri Payman Khorami 《天然气化学杂志》2010,19(1):91-95
Effects of carbon nanotubes (CNT) and alumina (γ-Al2O3) supports on the catalytic activities of hydrodesulfurization (HDS) process over CoMo catalyst have been studied. XRD results indicated that the main active phases in CNT and γ-Al2O3 supported Co-Mo catalysts are MoO2 and MoO3, respectively. The TPR results reveal that the reduction peak temperatures of the active species on CNT supported Co-Mo catalyst is lower than those on alumina supported Co-Mo catalyst, indicating that the CNT supports favor the r... 相似文献
284.
High-Resolution Temporo-Ensemble PIV to Resolve Pore-Scale Flow in 3D-Printed Fractured Porous Media
Ahkami Mehrdad Roesgen Thomas Saar Martin O. Kong Xiang-Zhao 《Transport in Porous Media》2019,129(2):467-483
Transport in Porous Media - Fractures are conduits that can enable fast advective transfer of (fluid, solute, reactant, particle, etc.) mass and energy. Such fast transfer can significantly affect... 相似文献
285.
Ilia Kochetygov Anita Justin Mehrdad Asgari Shuliang Yang Vikram Karve Till Schertenleib Dragos Stoian Emad Oveisi Mounir Mensi Wendy L. Queen 《Chemical science》2022,13(21):6418
Using azolium-based ligands for the construction of metal–organic frameworks (MOFs) is a viable strategy to immobilize catalytically active N-heterocyclic carbenes (NHC) or NHC-derived species inside MOF pores. Thus, in the present work, a novel copper MOF referred to as Cu-Sp5-BF4, is constructed using an imidazolinium ligand, H2Sp5-BF4, 1,3-bis(4-carboxyphenyl)-4,5-dihydro-1H-imidazole-3-ium tetrafluoroborate. The resulting framework, which offers large pore apertures, enables the post-synthetic modification of the C2 carbon on the ligand backbone with methoxide units. A combination of X-ray diffraction (XRD), solid-state nuclear magnetic resonance (ssNMR) and electron microscopy (EM), are used to show that the post-synthetic methoxide modification alters the dimensionality of the material, forming a turbostratic phase, an event that further improves the accessibility of the NHC sites promoting a second modification step that is carried out via grafting iridium to the NHC. A combination of X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) methods are used to shed light on the iridium speciation, and the catalytic activity of the Ir–NHC containing MOF is demonstrated using a model reaction, stilbene hydrogenation.A new MOF with a saturated N-heterocyclic carbene ligand undergoes a series of structural transformations to produce a turbostratic material, which serves as a better support for an iridium hydrogenation catalyst, when compared to the parent material. 相似文献
286.
Negin Davoodian Ali Nakhaei Pour Mohammad Izadyar Ali Mohammadi Alireza Salimi Seyed Mehdi Kamali Shahri 《应用有机金属化学》2020,34(9):e5747
The Fischer–Tropsch synthesis using cobalt catalysts supported on zeolitic imidazolate frameworks (ZIFs), ZIF-7 and ZIF-8, has been investigated. ZIF-7, ZIF-8 and corresponding cobalt-containing catalysts, after preparation, were characterized using various techniques. Thermogravimetric analysis results show that ZIF-7 and ZIF-8 supports have good thermal stability for the Fischer–Tropsch synthesis reaction, and weaker interaction between cobalt and zinc in the ZIF-7 and ZIF-8 supports results in more cobalt reduction. The catalytic performance was evaluated in Fischer–Tropsch synthesis and compared with that of a cobalt catalyst supported on SBA-15 promoted with zinc. The pore structure of the ZIF supports plays an essential role in product selectivity for the prepared catalysts. The carbon number in hydrocarbon products and olefin selectivity depend on cobalt dispersion and support structure owing to the impacts of site density and carrier skeleton on the speed of diffusion-enhanced olefin re-adsorption reactions. 相似文献
287.
Yan Cao Afrasyab Khan Hanzaleh Balakheyli Andrew Ng Kay Lup Mohammad Ramezani Taghartapeh Hassan Mirzaei Seyed Reza Khandoozi Alireza Soltani Mehrdad Aghaei Fatemeh Heidari Shaheen M. Sarkar Ahmad B. Albadarin 《Arabian Journal of Chemistry》2021,14(7):103200
The adsorption of penicillamine (PCA) on pure B12N12 and B12CaN12 nanocages in aqueous and chloroform solvents has been evaluated using density functional theory (DFT) calculations. The interaction of PCA on B12N12 nanocages is chemisorption through its four nucleophilic sites: amine, carbonyl, hydroxyl and thiol. The most stable adsorption configuration was achieved when zwitterionic PCA adsorbs via its carbonyl group in water with value of ?1.723 eV, in contrast, when neutral PCA adsorbs via its amine group in chloroform with value of ?1.68 eV. Intercalated calcium ion within B12N12 nanocage (B12CaN12) was shown to attract PCA onto nanocage surface, resulting in higher solubility and adsorption energy after their complexation in water and chloroform. The adsorption of multiple PCA molecules from their amine and carbonyl groups on pure and B12CaN12 nanocages were also evaluated where two and three molecules can be chemisorbed on boron atoms of the nanocage surfaces with the adsorption energy per PCA reduces slightly with the increasing the amount of drugs due to the curvature effects. Molecular docking study indicates that PCA from its NH2 group on B12CaN12 nanocage has the best binding affinity and inhibition potential of tumor necrosis factor-alpha (TNF-α) and Interleukin-1 (IL-1) receptors as compared with the other adsorption systems. Molecular docking and ADMET analysis displayed that the chosen compounds pass Lipinski Rule and have appropriate pharmacokinetic features suitable as models for developing anti-inflammatory agents. 相似文献
288.
Khodabandeh Erfan Akbari Omid Ali Akbari Soheil Taghizadeh Afshin Saffari Pour Mohsen Ersson Mikael Jönsson Pär G. 《Journal of Thermal Analysis and Calorimetry》2021,144(1):245-256
Journal of Thermal Analysis and Calorimetry - In this numerical study, the variations in the surface area of the cooling channels in a solid oxide fuel cell with different cross sections... 相似文献
289.
In this study, density functional theory (DFT) molecular modeling studies were performed to explore mechanisms underlying the interactions of cocatalysts in Ziegler–Natta olefin polymerization using a range of commercially available cocatalysts, namely, trimethylaluminum (in monomeric and dimeric form, Al2Me6), dimethylaluminum chloride (in monomeric and dimeric form, Al2Me4Cl2), and triisobutylaluminum. In this regard, after exploring structural and electronic features of cocatalysts, by steric maps and conceptual DFT, their interaction with possible impurities in hydrocarbon solvents and monomer feeds such as NH3, CH3OH, H2O, H2S, CO2, and O2 was considered. Then, activation of Ti species, adsorbed on the (110) and (104) surfaces, with the assistance of cocatalysts was studied as well. In this aspect, two possible reactions were investigated: (i) formation of first vacancy on Ti center and (ii) formation of first Ti–C bond by transalkylation reaction with cocatalysts. Finally, the effect of cocatalysts on the stereospecificity of Ti center adsorbed on the (110) surface was also taken into account by DFT calculations. 相似文献
290.
ABSTRACTPrecipitate hardening is a key strengthening mechanism in metallic alloys. Classical models for precipitate hardening are based on the average behaviour of an ensemble of precipitates, and fail to capture the complexity of dislocation-precipitate interactions that have recently been observed at individual precipitates in simulations and in-situ electron microscopy. In order to achieve tailored mechanical properties, detailed deformation mechanisms at specific precipitates that account for precipitate size, crystallography, and defect structure must be understood, but has been challenging to achieve experimentally. Here, in-situ scanning electron microscope mechanical testing is used to obtain the compressive stress–strain behaviour at an individual, incoherent Au precipitate within a Cu nanocube, and determine the influence of precipitate and cube size on yield strength and strain hardening. TEM imaging and strain mapping of the initial structure shows misfit dislocations at the Au precipitate, threading dislocations that traverse the Cu shell, and localised and anisotropic strain near the precipitate and threading dislocation. These nanocubes have yield strengths of 800–1000?MPa and strain hardening rate of 1–4?GPa. Yield strength is found to depend on the distance from the precipitate interface to the cube edge, while strain hardening depends on both cube size and precipitate size. An analytical model is developed to quantify the contribution of Orowan looping, Orowan stress, back stress and image stress to plasticity at the Au precipitate. Orowan stress is found to be the largest contributor, followed by back stress and image stress. 相似文献