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991.
《Arabian Journal of Chemistry》2022,15(10):104167
There had been some reports demonstrating the green synthesis of silver nanoparticles using guava (Psidium guajava (L.) extract); however, detailed and in-depth interrogation of the vital synthesis parameters for rapid, facile, efficacious synthesis at room temperature, and robust characterization of the as-prepared nanoparticle is currently lacking. This study presents a comprehensive delineation of the sustainable phyto-fabrication of biogenic guava phenolic extract functionalized silver nanoparticles (GVE-SNP) based on guava phenolic extract as the sole reductant/stabilizer, as well as the synthesis optimization, thorough physicochemical characterization and potential biological applications of the as-prepared nanosilver. The results revealed that successful synthesis of GVE-SNP was instantaneous and maximum intensity of the plasmonic peak at 425 nm was achieved in less than 10 min. GVE-SNP was found to present stable, well-dispersed, round, uniform, and crystalline nanoparticles of about 5.88 nm. The FTIR and RAMAN spectra indicated that GVE-SNP surface was properly capped by bioactives from GVE. The nanoparticles displayed potent radical scavenging activity against ABTS+ and DPPH. Also, GVE-SNP exhibited a significant and dose–response inhibitory effect against tyrosinase. Furthermore, the nanoparticles displayed good cytotoxicity against L929 fibroblast and were found to possess strong antimicrobial properties, inhibiting the growth of S. aureus and S. epidermidis. 相似文献
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Krismastuti Fransiska Sri Herwahyu Sujarwo Sujarwo Hindayani Ayu Hamim Nuryatini Tangpaisarnkul Nongluck Hongthani Wiphada 《Accreditation and quality assurance》2019,24(2):119-125
Accreditation and Quality Assurance - The Research Centre for Chemistry—Indonesian Institute of Sciences (RCChem-LIPI) organized an unofficial bilateral comparison on electrolytic... 相似文献
995.
Nutsara Deepankeaw Dr. Thana Maihom Prof. Dr. Michael Probst Anittha Prasertsab Kan Homlamai Dr. Jarinya Sittiwong Prof. Dr. Jumras Limtrakul 《Chemphyschem》2019,20(16):2122-2126
We investigate the tautomerization of phenol catalyzed by acid-base active pair sites in Lewis acidic Beta zeolites by means of density functional calculations using the M06-L functional. An analysis of the catalytic mechanism shows that hafnium on the Beta zeolite causes the strongest absorption of phenol compared to zirconium, tin, and germanium. This can be rationalized by the highest delocalization of electron density between the Lewis site and the oxygen of phenol which can in turn be quantified by the perturbative E(2) stabilization energy. The reaction is assumed to proceed in two steps, the phenol O−H bond dissociation and the protonation of the intermediate to form the cyclohexa-2,4-dien-1-one product. The rate determining step is the first one with a free activation energy of 26.3, 25.0, 22.1 and 22.7 kcal mol−1 for Ge-Beta, Sn-Beta, Zr-Beta, and Hf-Beta zeolites, respectively. The turnover frequencies follow these reaction barriers. Hence, the intrinsic catalytic activity of the Lewis acidic Beta zeolites studied here is in the order of Hf-Beta≈Zr-Beta>Sn-Beta> Ge-Beta for the tautomerization of phenol. 相似文献
996.
S. Bernstein K.T. Fehr 《Progress in Crystal Growth and Characterization of Materials》2012,58(2-3):84-91
The influence of grain size of quartz on the formation of 1.13 nm tobermorite in aerated autoclaved concrete was investigated by applying in-situ neutron diffraction. Experiments were performed at 210 °C/Psat employing quartz of 8 μm and 16 μm, respectively. The results reveal changes in the reaction mechanism from solution control to diffusion control. The grain size of the quartz fraction clearly influences the occurrence of those changes. Based on those results an interpretation of former not clearly interpretable quenching experiments was performed. An interpretation using different reaction mechanisms for those experiments leads to a coherent picture of the reaction. 相似文献
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David Elbaz Sophia Buhbut Benjamin Zeev Kupfer Arie Zaban Zeev Zalevsky 《Optics Communications》2012,285(10-11):2746-2749
In this paper we present a new type of optical fiber aiming to radially polarize the electrical field. This special device is composed of a tapered fiber having a classical core while on top of its external surface, radially oriented nanorods are disposed. The tails of the propagated wave are interacting with those radially oriented nanorods. This interaction performs the polarization of the propagated mode into a radial polarization. 相似文献
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The aim of the present paper is to introduce the notion of weak reciprocal continuity and obtain fixed point theorems by employing
the new notion. The new notion is a proper generalization of reciprocal continuity and is applicable to compatible mappings
as well as noncompatible mappings. Our results generalize several fixed point theorems. 相似文献