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111.
Raman spectroscopy is a common tool for the qualitative and quantitative chemical analysis of molecules. Although the unique identification of molecules is possible via their vibrational lines, high concentrations (mmol/l) are needed for their nonresonant excitation owing to their low scattering cross section. The intensity of the Raman spectra is amplified by the use of the surface‐enhanced Raman scattering (SERS) technique. While the use of silver sols results only in a limited reproducibility of the Raman line intensities, lithographically designed, nanostructured gold surfaces used as SERS‐active substrates should, in principle, combine the high sensitivity with better reproducibility. For this purpose, we have produced gratings of gold dots on Si(001) surfaces by means of electron beam lithography. Qualitative and quantitative investigations of crystal violet (CV) performed using nanostructured surfaces give high reproducibility and enhancement of the Raman lines. The substrates are reusable after cleaning; all results presented could be obtained from a single SERS substrate. For the experiments very low laser powers were used. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
112.
Ximei Sun Yan Li Qian Yang Yunwei Xiao Yuting Zeng Jindi Gong Ziyu Wang Xiaofeng Tan He Li 《中国化学快报》2021,32(5):1780-1784
Traditional colorimetric glucose biosensor generally involves complex assay procedures. Free labile enzymes and peroxidase substrates are used separately for triggering a chromogenic reaction. These limits result in inferior enzyme stability and defective enzymatic catalytic efficiency, making it hard to routinely utilize them for the direct and fast test of glucose. In this work, we provide an all-inclusive substrates/enzymes nanoparticle employed 3,3′5,5′-tetramethylbenzidine (TMB) as chromogenic substrates and glucose oxidase (GOx)/horseradish peroxidase (HRP) as signal amplifier enzymes (TMB-GH NPs) by the molecule self-assembly technique. The “all-inclusive” nanoparticles can realize the tandem colorimetric reactions, and the oxidation product of TMB (ox-TMB) exhibits a strong NIR laser-driven photothermal effect, thus allowing quantitative photothermal detection of glucose. Owing to the restriction of the molecular motion of GOx, HRP, and TMB, the distance of mass transfer between substrates was shortened largely, leading to improved catalytic activity for glucose. Overall, our strategy will simplify the analysis procedure, furthermore, these integrated nanoparticles not only display higher stability and activity than that of the free GOx/HRP system and possesses an excellent performance for colorimetric and photothermal bioassay of glucose simultaneously. We believe that this unique technique will give good inspirations to develop simple and precise methods for bioassay. 相似文献
113.
P. Arendt N. Elliott R. Dye K. Hubbard M. Maley J. Martin Y. Coulter B. Bennett 《Journal of Electronic Materials》1992,21(5):499-501
A multi-step process is used to fabricate Tl2Ba2Ca1Cu2O8 films on (100) LaA103 substrates. Submicron thick precursor films of Ba-Ca-Cu-O are rf magnetron sputter deposited from a single target. Film stoichiometry
is measured by ion beam backscattering spectroscopy. Deficiencies of the alkaline earths that are found in the precursor films
are then compensated for by the addition of appropriate CaF2 and/or BaF2 films onto the surface of the precursor film. Post deposition annealing of the films is then done in an atmosphere of thallium
oxide and oxygen in order to form the superconducting phases. The annealed films are examined using x-ray diffraction (XRD),
an ac inductance technique, and critical current in an external magnetic field. XRD shows the c-axis length of the superconducting
phase to increase as the overall film stoichiometry approaches 2212. The transition widths measured by inductive coupling
weakly correlate with 77 K critical current measurements. Our best critical current results are 1.5*106 amps/ cm2 for a film measured at 4 K in an 8 T magnetic field (parallel to the films' c-axis). 相似文献
114.
Noriaki Funasaki 《Journal of inclusion phenomena and macrocyclic chemistry》2004,50(1-2):43-50
The interactions between cyclodextrin and substrates having two binding sites in aqueous solution are reviewed. For such substrates, multiple equilibria, NMR chemical shift variations with full binding, solution structures of complexes, and the effect of cavity size are analyzed quantitatively. After general treatments of multiple equilibria and chemical shifts are given, they are applied to three bivalent substrates of diheptanoyllecithin, dialkyldimethylammonium bromide, and oxyphenium bromide for demonstrating their usefulness. The solution structures of complexes play a crucial role in these basic researches as well as the applications of cyclodextrins, such as bitter taste reduction and stabilization of labile substrates. 相似文献
115.
Thin titanium dioxide films are deposited on glass substrates by magnetron sputter deposition. They are irradiated in air, by means of a KrF excimer laser. The ablation rate is measured as a function of the laser fluence per pulse, F, and of the number of pulses, N. Above a fluence threshold, the films are partially ablated. The ablated thickness does not vary linearly with N. This is the signature of a negative feedback between the film thickness and the ablation rate. The origin of this negative feedback is shown to be due to either thermal or electronic effects, or both. At high F, the film detachs from the substrate. 相似文献
116.
X. Li D. V. Forbes S. Q. Gu D. A. Turnbull S. G. Bishop J. J. Coleman 《Journal of Electronic Materials》1995,24(11):1711-1714
High quality GaN films have been grown on sapphire substrates (C face and A face) by atmospheric pressure metalorganic chemical
vapor deposition (MOCVD) using a new buffer layer. With our reactor configuration and growth parameters, a GaN film grown
on a single GaN buffer layer appears opaque with high density of hexagonal pits. Using a single A1N buffer layer results in
extremely nonuniform morphology with mirror-like areas near the edge of the substrates and opaque areas in the center. The
double buffer layer we report here, with GaN as the first layer and A1N as the second, each with an optimized thickness, leads
to mirror-like films across the entire substrate. Scanning electron microscopy, photoluminescence, x-ray diffraction, and
van der Pauw geometry Hall measurement data are presented to establish the quality of our films. The mechanism for this new
buffer layer is also discussed. 相似文献
117.
Characteristics of fluorogenic substrates designed for detection of enzyme activity in living cells are reviewed. Improved retention of the fluorescent products in the cell of origin can be achieved by structural modifications to the substrate that result in association with membrane lipids or conjugation to intracellular glutathione. Newly-developed substrates that yield fluorescent precipitates provide the additional advantage of allowing subcellular localization of sites of enzymatic activity. Improved detection sensitivity can also be achieved by targeted delivery of substrates for processing by specific organelles. Substrates designed for monitoring oxidative activity and lipid metabolism provide examples of this approach. 相似文献
118.
119.
A universal and straightforward method for the preparation of polymer brushes via the formation of Si-C bond on silicon substrates through the UV-induced photopolymerization is demonstrated. 相似文献
120.
Yuan-Guo Wu Xing-Bao Zhu Wei-Hua Wan Zi-Ning Man Yu Wang Zhe Lü 《Advanced functional materials》2021,31(49):2105664
Modern technology constantly requires smaller, more efficient lithium–oxygen batteries (LOBs). To meet this need, a chemical vapor deposition (CVD) method is used to create an innovative cathode design with both a hierarchical porous nanostructure and a 3D flexible macroscopical morphology. This method employs architectural optimization to further improve cathodic ORR and OER performance via heteroatom doping, surface-sprouted carbon nanofibers (CNFs) grafting, and boundary exposing. The cathode consists of a 3D hierarchical porous graphene foam (PGF), along with RuO2 nanoparticles impregnated and nitrogen doped CNFs (RuO2@NCNFs), where the PGF serves as a structural support and cathodic current collector, and the RuO2@NCNFs work as a superior bi-functional catalyst. The cathode delivers an outstanding discharge capacity of 8440 mAh gcathode−1 while maintaining a recharge plateau at ≈4.0 V, and can cycle for over 700 rounds without obvious degeneration under a fixed capacity. Notably, this free-standing cathode can be directly used in LOBs without the need for additional substrates or current collectors. Therefore, the current densities and capacities herein are calculated based on the total weight of the cathodes. These results demonstrate the RuO2@NCNFs-PGF cathode's remarkable potential for LOB applications, and this rational cathodic structure may be extended to other highly efficient catalyst applications. 相似文献