Summary Multipulse experiments reveal qualitative and quantitative, time-resolved information about the interaction of N2O with ZSM-5 type zeolites under conditions of catalytic applications, like the mechanism of N2O decomposition, amount and reactivity of an atomic surface oxygen species. 相似文献
An unsymmetrical tetradentate Schiff base (H2L) was synthesized by the reaction of 3-methoxysalicylaldehyde, o-phenylenediamine, and salicylaldehyde in EtOH. H2L was characterized by single-crystallographic X-ray analysis. Its Co(II) and Mn(III) complexes ([CoL] and [MnLCl]) were prepared and immobilized on 3-aminopropyltriethoxysilane functionalized silica gel. The immobilized materials were found to be efficient catalysts for epoxidation of styrene in the presence of tert-BuOOH in acetonitrile at 40 °C. The catalysts can be reused several times without significant loss of performance. 相似文献
In this work, (3,6-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-9-(4-vinylbenzyl)-9H-carbazole) (EDOTVBCz) comonomer was chemically synthesized and characterized by Fourier transform infrared (FTIR), proton nuclear magnetic resonance, and carbon nuclear magnetic resonance spectroscopy. EDOTVBCz was electrocoated on glassy carbon electrode (GCE) in various initial molar concentrations ([EDOTVBCz]0?=?1.0, 1.5, 2.0, and 3.0) in 0.1 M lithium perchlorate (LiClO4)/acetonitrile (CH3CN). P(EDOTVBCz)/GCE was characterized by cyclic voltammetry, FTIR reflectance-attenuated total reflection spectroscopy, scanning electron microscopy–energy dispersive X-ray analysis, atomic force microscopy, and electrochemical impedance spectroscopy (EIS). EIS was used to determine the capacitive behaviors of modified GCE via Nyquist, Bode magnitude, Bode phase, and admittance plots. The highest low-frequency capacitance value was obtained as CLF?=?~2.35 mF cm?2 for [EDOTVBCz]0?=?3.0 mM. Double-layer capacitance of the polymer/electrolyte system was calculated as Cdl?=?~2.78 mF cm?2 for [EDOTVBCz]0?=?1.0 and 3.0 mM. The maximum phase angle was obtained as θ?=?~76.7o for [EDOTVBCz]0?=?1.0, 1.5, 2.0, and 3.0 mM at the frequency of 20.6 Hz. AC impedance spectra of P(EDOTVBCz)/LiClO4/CH3CN was obtained by performing electrical equivalent circuit model of R(Q(R(CR))) with linear Kramers–Kronig test.
Figure
SEM-EDX analysis of P(EDOTVBCz)/CFME EDX point analysis inset: SEM point analysis, [EDOTVBCz]0?=?3 mM. Chronoamperometric method of constant potential at 1.6 V, 300 s in 0.1 M LiClO4/CH3CN 相似文献
It is shown that the two-step excitation scheme typically used to create an ultracold Rydberg gas can be described with an effective two-level rate equation, greatly reducing the complexity of the optical Bloch equations. This allows us to efficiently solve the many-body problem of interacting cold atoms with a Monte Carlo technique. Our results reproduce the observed excitation blockade effect. However, we demonstrate that an Autler-Townes double peak structure in the two-step excitation scheme, which occurs for moderate pulse lengths as used in the experiment, can give rise to an antiblockade effect. It is most pronounced for atoms arranged on a lattice. Since the effect is robust against a large number of lattice defects it should be experimentally realizable with an optical lattice created by CO2 lasers. 相似文献
We study a first-order method to find the minimum cross-sectional area ellipsoidal cylinder containing a finite set of points. This problem arises in optimal design in statistics when one is interested in a subset of the parameters. We provide convex formulations of this problem and its dual, and analyze a method based on the Frank–Wolfe algorithm for their solution. Under suitable conditions on the behavior of the method, we establish global and local convergence properties. However, difficulties may arise when a certain submatrix loses rank, and we describe a technique for dealing with this situation. 相似文献
This paper describes a new support that permits to efficient immobilization of L-asparaginase (L-ASNase). For this purpose, Fe3O4 magnetic nanoparticles were synthesized and coated by MCM-41. 3-chloropropyltrimethoxysilane (CPTMS) was used as a surface modifying agent for covalent immobilization of L-ASNase on the magnetic nanoparticles. The chemical structure; thermal, morphological, and magnetic properties; chemical composition; and zeta potential value of Fe3O4@MCM-41-Cl were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), differential scanning calorimetry (DSC), vibrating sample magnetometer (VSM), scanning electron microscope (SEM), energy dispersive X-ray (EDX), X-ray diffraction patterns (XRD), and zeta-potential measurement. The immobilization efficiency onto Fe3O4@MCM-41-Cl was detected as 63%. The reusability, storage, pH, and thermal stabilities of the immobilized L-ASNase were investigated and compared to that of soluble one. The immobilized enzyme maintained 42.2% of its original activity after 18 cycles of reuse. Furthermore, it was more stable towards pH and temperature compared with soluble enzyme. The Michaelis–Menten kinetic properties of immobilized L-ASNase showed a lower Vmax and a similar Km compared to soluble L-ASNase. Immobilized enzyme had around 47 and 32.5% residual activity upon storage a period of 28 days at 4 and 25 °C, respectively. In conclusion, the Fe3O4@MCM-41-Cl@L-ASNase core–shell nanoparticles could successfully be used in industrial and medical applications.
Journal of Solid State Electrochemistry - In this study, graphene oxide (GO) was chemically reacted with sodium borohydride (NaBH4) to form reduced graphene oxide (rGO). rGO and rGO/Zn... 相似文献
This review article investigates the hot topics by presenting the latest advances on graphene-based nanostructures for supercapacitors. In literature, many scientists have studied the nanomaterials and combination of conducting polymers in supercapacitor (SC) devices. The main aim of this review article is to present the higher capacitance, and higher power and energy density performances of the SC devices, which includes the active materials of carbon-based materials, metal oxides, conducting polymers, nanocomposites, etc. Many conventional techniques have already been used such as photolithography, inkjet printing, etc. Each of these methods has specific advantages and some drawbacks, with some working better in different environments. Among various nanoscaled materials, nanocrystal oxides of transition metals play an important role in advanced materials development. In addition to design of active material, symmetric and asymmetric supercapacitor device fabrication is also directly effect to obtain a higher capacitance, energy and power density performances. Therefore, this review article focuses on supercapacitor technology in new developments, such as design of active materials, device fabrication, etc. 相似文献
We present the first integration of fluidically tunable filters with a separate particle detection channel on a single planar, optofluidic chip. Two optically connected, but fluidically isolated liquid-core antiresonant reflecting optical waveguide (ARROW) segments serve as analyte and spectral filter sections, respectively. Ultrasensitive detection of fluorescent nanobeads with high signal-to-noise ratio provided by a fluidically tuned excitation notch filter is demonstrated. In addition, reconfigurable filter response is demonstrated using both core index tuning and bulk liquid tuning. Notch filters with 43 dB rejection ratio and a record 90 nm tuning range are implemented by using different mixtures of ethylene glycol and water in the filter section. Moreover, absorber dyes and liquids with pH-dependent transmission in the filter channel provide additional spectral control independent of the waveguide response. Using both core index and pH control, independent filter tuning at multiple wavelengths is demonstrated for the first time. This extensive on-chip control over spectral filtering as one of the fundamental components of optical particle detection techniques offers significant advantages in terms of compactness, cost, and simplicity, and opens new opportunities for waveguide-based optofluidic analysis systems. 相似文献