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991.
Xinxian Zhong Jinhua Chen Bo Liu Yan Xu Yafei Kuang 《Journal of Solid State Electrochemistry》2007,11(4):463-468
Organic molecule neutral red (NR), as electron transfer mediator, was introduced in the anodic electrocatalyst system for
methanol oxidation and the resulting electrode was investigated by cyclic voltammetry, polarization method, and electrochemical
impedance spectroscopy. For the same loading mass of platinum catalyst, 1.25 times larger exchange current density, 1.83 times
higher specific activity, and better long-term cycle stability can be obtained at Pt/NR/graphite electrode, as compared to
the electrode without NR. These results indicate that neutral red plays an important role on the enhanced electrocatalytic
activity of platinum catalyst for methanol oxidation. 相似文献
992.
Aleksandr R. Cholach Vladimir M. Tapilin 《Reaction Kinetics and Catalysis Letters》2005,86(2):315-321
Summary Disappearance Potential Spectroscopy study of the oxygen adsorption on the Pt(100)-(1×1) single crystal surface revealed a
regular set of spectral satellites designated as the platinum bulk plasmons. 相似文献
993.
994.
Fengyu Zhao Yutaka Ikushima Masayuki Shirai Takeo Ebina Masahiko Arai 《Journal of molecular catalysis. A, Chemical》2002,180(1-2)
The selective hydrogenation of cinnamaldehyde (CAL) was investigated using silica supported platinum catalysts in supercritical carbon dioxide. Selectivity to cinnamyl alcohol (COL) is enhanced as Pt0/Pt2+ ratio increases; namely, zero-valent metallic surface is beneficial to the formation of COL compared with less reduced surface. The influence of Pt0/Pt2+ ratio is more significant on the selectivity than on the total conversion. For the catalyst with small Pt0/Pt2+ value, the selectivity also depends on the degree of platinum dispersion. The selectivity to COL is higher for higher degree of platinum dispersion. The CO2 pressure did not affect the conversion and selectivity so much. 相似文献
995.
Nuriye Kocak Mustafa Sahin Ilker Akin Mahmut Kus Mustafa Yilmaz 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(10):776-779
Chitosan nanoparticles (CHN) were prepared based on ionotropic gelation between low moleculer weight chitosan and sodium tripolyphosphate (TPP) under microwave irradiation. Particle size, zeta potential, and FT-IR techniques were used for characterization of CHN. The influence of reaction time on the nanoparticle size distribution was investigated, and the results showed that the microwave irradiation method evidently decreases the reaction times and particle size over the conventional method. It was determined by the results of the zeta potential measurements that synthesized CHN under microwave irradiation clearly exhibits more homogeneous and stable dispersion. 相似文献
996.
Ian C. Watson André Schumann Haoyang Yu Prof. Dr. Emma C. Davy Dr. Robert McDonald Dr. Michael J. Ferguson Prof. Dr. Christian Hering-Junghans Prof. Dr. Eric Rivard 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(41):9678-9690
New N-heterocyclic olefins (NHOs) are described with functionalization on the ligand heterocyclic backbone and terminal alkylidene positions. Various PdII–NHO complexes have been formed and their use as pre-catalysts in Buchwald–Hartwig aminations was explored. The most active system for catalytic C−N bond formation between hindered arylamine and arylhalide substrates was accessed by combining a backbone methylated NHO with [Pd(cinnamyl)Cl]2 in the presence of NaOtBu as a base. In these active systems evidence suggests that catalysis is mediated by colloidal palladium metal, highlighting a different coordination ability of NHOs in comparison with commonly used N-heterocyclic carbene co-ligands. 相似文献
997.
Ghobad Mohammadi Mohammad Mahdi Zangeneh Akram Zangeneh Zahra Minoosh Siavosh Haghighi 《应用有机金属化学》2020,34(1):e5136
The aim of the recent research was to investigate the anti-breast cancer effects of silver nanoparticles using Phoenix dactylifera seed ethanolic extract (AgNPs). After preparation of Phoenix dactylifera seed extract, GC/MS was performed to detect the compounds. The findings indicated that 9-Octadecenoic acid (Z)- methyl ester (40.95%) and Dodecanoic acid methyl ester (20%) were the most frequent constituents found in P. dactylifera. These nanoparticles were spherical with a size range of 17-19 nm and characterized using various analytical techniques including UV–Vis absorption spectroscopy to determine the presence of AgNPs in the solution. We studied functional groups of P. dactylifera extract in the reduction and capping process of AgNPs by FT-IR, crystallinity and FCC planes by X-ray diffraction (XRD) pattern and surface morphology, shapes, and size of AgNPs by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). DPPH free radical scavenging test was used to test the antioxidant properties of P. dactylifera and AgNPs, which revealed high antioxidant potential similar to butylated hydroxy toluene (BHT) as the positive control. The results of cytotoxicity analysis indicated that P. dactylifera and AgNPs were toxic for MCF-7 cells. In vivo design, induction of breast cancer was done by 7,12-Dimethylbenz[a] anthracene (DMBA) in 50 animals. After 10 days, the animals were randomly divided into six subgroups, including healthy control, untreated control, two groups receiving the P. dactylifera at 2 and 6 mg/kg and two groups receiving the AgNPs at 2 and 6 mg/kg concentrations. Both doses of P. dactylifera and AgNPs (especially AgNPs6) significantly (p ≤ 0.05) reduced the weight and volume of liver, mammary gland, kidney, spleen, ALP, AST, ALT, GGT, cholesterol, LDL, triglyceride, total and conjugated bilirubin, urea, creatinine, glucose, ferrous, ferritin, erythropoietin, GR, IL1, IL6, IL12, IL18, IFNY, and TNFα and increased HDL, total protein, albumin, WBC, lymphocyte, neutrophils, platelet, RBC, Hb, PCV, MCV, MCH, MCHC, SOD, CAT, GPx, IL4, IL5, IL10, IL13, and IFNα compared to the untreated group. Moreover, P. dactylifera and AgNPs (especially AgNPs6) significantly (p ≤ 0.05) treated breast cancer with reduction of organs free of metastasis compared to the untreated group. Seemingly, the AgNPs can be used for the treatment of breast cancer. 相似文献
998.
Core–shell and gradient morphology polymer particles analyzed by X‐ray photoelectron spectroscopy: Effect of monomer feed order 下载免费PDF全文
Florent Jasinski Victoria L. Teo Rhiannon P. Kuchel Monique Mballa Mballa Stuart C. Thickett Richard H. G. Brinkhuis William Weaver Per B. Zetterlund 《Journal of polymer science. Part A, Polymer chemistry》2017,55(15):2513-2526
The synthesis of composite latex particles possessing core–shell and gradient morphologies, respectively, using seeded starve‐fed semibatch emulsion polymerization of styrene (St) and methyl methacrylate (MMA) is presented. The focus is on the effect of the monomer feed order on the particle morphology development. The particle morphology is assessed using a novel approach which entails comparing the experimental surface composition as a function of polymerization time (particle growth) obtained by X‐ray photoelectron spectroscopy with the predicted surface composition using a mass balance mathematical model. Both types of composite latexes (core–shell and gradient) feature changes with polymerization time in the oxygen/carbon surface composition which enables one to track the morphology development. Differential scanning calorimetry is also implemented to analyze the extent of phase separation. The monomer feed order is shown to play a crucial role—under the present conditions, gradient and core–shell particles are obtained if the feed order is St/MMA (St fed first), but not if the feed order is reversed. These findings illustrate that thermodynamic factors are important, given that thermodynamically it is more favorable for MMA‐rich chains to occupy the oil–water interface to reduce the interfacial tension. Systems where St is the second stage monomer lead to mixed structures rather than the targeted core–shell or gradient morphology with St‐rich chains at the particle surface. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2513–2526 相似文献
999.
《中国化学会会志》2018,65(8):982-988
CuAg nanoparticles (CuAgNPs) were electrochemically formed in situ on pre‐anodized, screen‐printed carbon electrodes (SPCEs) that possessed many oxygen‐containing functional groups capable of adsorbing metal ions, namely Cu2+ and Ag+. Pre‐anodization was achieved using continuous cyclic voltammetry in the range of potential 0.3–2.0 V under a scan rate of 50 mV/s. Cu2+ and Ag+ ions were adsorbed on the pre‐anodized SPCE by immersing the electrode in solutions containing both metal ions, and then CuAgNPs were formed in situ via electrochemical reduction in a deaerated, neat NaClO4 solution after the electrode was ultrasonicated to remove physically adsorbed metal ions. Although CuNPs showed higher activity than AgNPs toward both nitrate (NO3−) and nitrite (NO2−) ions, the instability of CuNPs hindered the application, so CuAgNPs were employed to achieve a compromise between sensitivity and stability. The SPCE/anodized/CuAgNP electrodes showed activity toward the electrochemical reduction of NO3− and NO2−, respectively, with the limit of detection (LOD) of 15.6 μM (0.97 ppm) and 11.1 μM (0.51 ppm), which is sufficient to fit the allowed values (50 and 3 ppm, respectively) in drinking water as suggested by the World Health Organization (WHO). 相似文献
1000.
Because of their unique characteristics, DNAs have been widely studied for uses in biosensors. In this work, we utilize single-stranded homopolymeric deoxyadenosines (abbreviated as poly (dA)) as recognition elements and gold nanoparticles (abbreviated as AuNPs) as reporter parts for the construction of pH alarms, which are able to produce sharp colorimetric responses upon specific pH thresholds within the range from pH 2 to 4. These biosensors are convenient to prepare and easy to operate. Their pH thresholds for colorimetric response can be easily tuned by changes of DNA strand length, concentration and DNA sequence. With an increase in the number of nucleotide bases per DNA chain while keeping the overall number of nucleotide base in the system constant, the pH threshold can be raised. Increasing the concentration of the single-stranded poly (dA) DNA lowers the pH response threshold. Moreover, as they can sense a range as narrow as a 0.4 pH unit which equals to 2.5 fold [H+] change, they can be used as a potential pH alarm for specific pH range. 相似文献