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991.
Sensing and catalytic decomposition of hydrogen peroxide by silicon carbide nanotubes: A DFT study 下载免费PDF全文
Roghaye Nurazar Zahra Fallah Ebrahimi Mehdi D. Esrafili Esmail Vessally 《International journal of quantum chemistry》2015,115(8):471-476
In this study, by carrying out detailed density functional theory calculations, we investigate the adsorption and stepwise decomposition of hydrogen peroxide (H2O2) over (6,0) and (7,0) zigzag silicon carbide nanotubes (SiCNTs). The results indicate that the H2O2 can be adsorbed on the exterior surface of the SiCNTs with noticeable adsorption energies and charge transfers. To gain insight into the catalytic activity of the surface, the interaction between the H2O2 and SiCNT is analyzed by detailed electronic analysis such as adsorption energy, charge density difference and activation barrier. The decomposition of H2O2 into O2 and H2 species can be viewed as the kinetically preferred reaction pathway for dehydrogenation of hydrogen peroxide over SiCNTs. There is also a curvature effect on the dehydrogenation kinetics of hydrogen peroxide, that small diameter SiCNTs with large curvature would be beneficial for decomposition of H2O2. © 2015 Wiley Periodicals, Inc. 相似文献
992.
研究了肽纳米纤维负载的Pd纳米颗粒催化卤代芳烃与羟基苯并三唑的直接偶合反应.结果表明,该偶合反应可在简单、绿色及温和的条件下进行,并可以较高产率生成相应的联芳.本文首次采用羟基苯并三唑作为苯基化试剂,且将肽纳米纤维作为一种新型可循环使用的载体,因而对现有合成方法是一个有益补充. 相似文献
993.
Marjani Ahmad Poursattar Hosseini Seyed Ali Shokri Zahra Maleki Nasim 《Research on Chemical Intermediates》2017,43(1):413-422
Research on Chemical Intermediates - N-formylation of different amines was carried out with formic acid in the presence of the Co3O4 nanoparticles as an efficient, stable heterogeneous catalyst to... 相似文献
994.
Ambreen Ayub Abdul Shakoor Tasneem Zahra Rizvi Esmat Elahi 《Polymer Science Series A》2017,59(2):233-241
In this study, the cadmium selenide quantum dots/polyaniline nanocomposites were prepared by in-situ polymerization technique and they were characterized using X-ray diffraction and Fourier transform infrared spectroscopy. The surface morphology was studied by scanning electron microscopy. The electrical and dielectric properties were investigated by using 4-probe mechanism and LCR meter respectively. The increase in dielectric constant was observed with the increase of quantum dots content in the nanocomposites. The frequency dependent AC conductivity followed the universal power law. The temperature dependent DC conductivity was found to be a typical for a semiconducting behavior following Mott’s 1D variable range hoping model. 相似文献
995.
Maryam Ghanbari-Movahed Zahra Ghanbari-Movahed Saeideh Momtaz Kaitlyn L. Kilpatrick Mohammad Hosein Farzaei Anupam Bishayee 《Molecules (Basel, Switzerland)》2021,26(4)
The dysregulation of Notch signaling is associated with a wide variety of different human cancers. Notch signaling activation mostly relies on the activity of the γ-secretase enzyme that cleaves the Notch receptors and releases the active intracellular domain. It is well-documented that γ-secretase inhibitors (GSIs) block the Notch activity, mainly by inhibiting the oncogenic activity of this pathway. To date, several GSIs have been introduced clinically for the treatment of various diseases, such as Alzheimer’s disease and various cancers, and their impacts on Notch inhibition have been found to be promising. Therefore, GSIs are of great interest for cancer therapy. The objective of this review is to provide a systematic review of in vitro and in vivo studies for investigating the effect of GSIs on various cancer stem cells (CSCs), mainly by modulation of the Notch signaling pathway. Various scholarly electronic databases were searched and relevant studies published in the English language were collected up to February 2020. Herein, we conclude that GSIs can be potential candidates for CSC-targeting therapy. The outcome of our study also indicates that GSIs in combination with anticancer drugs have a greater inhibitory effect on CSCs. 相似文献
996.
Zahra Azzouz Azzeddine Bettache Nawel Boucherba Alicia Prieto Maria Jesus Martinez Said Benallaoua Laura Isabel de Eugenio 《Molecules (Basel, Switzerland)》2021,26(9)
Plant biomass constitutes the main source of renewable carbon on the planet. Its valorization has traditionally been focused on the use of cellulose, although hemicellulose is the second most abundant group of polysaccharides on Earth. The main enzymes involved in plant biomass degradation are glycosyl hydrolases, and filamentous fungi are good producers of these enzymes. In this study, a new strain of Aspergillus niger was used for hemicellulase production under solid-state fermentation using wheat straw as single-carbon source. Physicochemical parameters for the production of an endoxylanase were optimized by using a One-Factor-at-a-Time (OFAT) approach and response surface methodology (RSM). Maximum xylanase yield after RSM optimization was increased 3-fold, and 1.41- fold purification was achieved after ultrafiltration and ion-exchange chromatography, with about 6.2% yield. The highest activity of the purified xylanase was observed at 50 °C and pH 6. The enzyme displayed high thermal and pH stability, with more than 90% residual activity between pH 3.0–9.0 and between 30–40 °C, after 24 h of incubation, with half-lives of 30 min at 50 and 60 °C. The enzyme was mostly active against wheat arabinoxylan, and its kinetic parameters were analyzed (Km = 26.06 mg·mL−1 and Vmax = 5.647 U·mg−1). Wheat straw xylan hydrolysis with the purified β-1,4 endoxylanase showed that it was able to release xylooligosaccharides, making it suitable for different applications in food technology. 相似文献
997.
Zahra Vosoughi Rahbari Mehrji Khosravan Ali Nemati Kharat 《Russian Journal of Applied Chemistry》2017,90(8):1315-1319
EU-1 zeolite was synthesized with high purity by a hydrothermal method and under optimum conditions: synthesis time 72 h, temperature 200°C, and aging time 12 h. Then, the synthesized EU-1 zeolite was modified by dealumination with nitric acid and the changes of the properties such as surface area, pore volume, and Si/Al ratio were investigated. The catalytic performance of these two catalysts was studied and compared with a commercial mordenite catalyst for meta-xylene isomerization reaction in a fixed bed reactor. The results showed that the modification of catalyst with acid increases Si/Al ratio from 25 to 50 due to the removal of a number of aluminium atoms from the framework of zeolite. Also the catalyst surface area increased from 300.237 m2 g?1 for EU-1 to 333.639 m2 g?1 for modified EU-1. According to results, the modified Eu-1 had higher para/ortho ratio, meta-xylene conversion, and para-xylene yield than EU-1 and commercial mordenite in the meta-xylene isomerization reaction. 相似文献
998.
Sulfonylbis(1,4-phenylene)bis(sulfamic acid) (SPSA) is easily prepared and recognized as a new heterogeneous catalyst by the reaction of 4,4′-sulfonyldianiline with chlorosulfonic acid. This reagent was used for the synthesis of the mono- and bis-chromene derivatives. All reactions were performed under mild reaction conditions in high to excellent yields. The advantages of using the SPSA as a heterogeneous catalyst in these reactions are: being environmentally friendly, low cost, commercially availability and easy to separate from the mixture of the reaction and high reusable catalyst. Using this catalyst, results in acceptable reaction time and high yields with high purity of the obtained products without utilizing any organic solvents. The catalyst was characterized by FT-IR, 1H NMR, 13C NMR, mass and TGA studies. All the products were characterized by FT-IR, 1H, 13C NMR, HRMS, melting point and elemental analyses. 相似文献
999.
Sajad Mousavifaraz Zahra Nadealian Valiollah Mirkhani Abbas Rahmati 《Journal of the Iranian Chemical Society》2017,14(8):1753-1763
In this research, two heterogeneous organic–inorganic hybrid catalysts, [bmim]3[PW12O40]·3H2O and [bmim]5[PNiW11O39]·3H2O, have been prepared. The catalysts were fully characterized by several techniques such as elemental analyses, Fourier transform infrared spectroscopy, thermo-gravimetric analysis, scanning electron microscope and energy-dispersive X-ray analysis. Next, the hybrid catalysts have been used for the synthesis of functionalized diazepines containing tetrazole ring. Tetrazolyl-1H-spiro[benzo[b]cyclopenta[e][1,4] diazepines products were obtained in excellent yields and mild experimental conditions using [bmim]5[PNiW11O39]·3H2O as catalyst. This process was carried out via a one-pot, pseudo-five-component condensation reaction by means of a 1,2-diamine, isocyanide, TMSN3 and two molecules of a linear or cyclic ketone in methanol, at ambient temperature. 相似文献
1000.
Mohammad Dinari Mohamad Mohsen Momeni Zahra Bozorgmehr Shiva Karimi 《Journal of the Iranian Chemical Society》2017,14(3):695-701
Layered double hydroxide (LDH)-based photocatalysts have emerged as a very promising candidate to replace TiO2, owing to their unique layered structure, tunable band gaps, low cost, ease of scale-up, and good photocatalytic activity. Bismuth-doped ZnCr-LDH was studied as photocatalyst in the photodegradation of methylene blue (MB). The structure and morphology of ZnCr-LDH and ZnCrBi-LDH were characterized using a different mode of delegated tools, e.g., FTIR, XRD, UV–Vis, FESEM–EDX, and TEM measurements. FESEM and TEM image of the synthesized LDHs showed that the synthesized LDH is smooth overlapping crystals, and they are approximately in hexagonal form. The material was found to be a good photocatalyst for degradation of methylene blue in visible light, and the results showed that the photocatalytic activity of ZnCrBi-LDH sample is higher than of ZnCr-LDH sample. According to the kinetic data, the reaction rate constant of ZnCrBi-LDH is approximately four times higher than the apparent reaction rate constant of ZnCr-LDH. The catalytic activity was retained even after four methylene blue degradation cycles, indicating that the LDH could be an important addition to the field of wastewater treatment. 相似文献