A new approach based on density functional theory and the Anderson impurity model is developed to calculate charging energies and quasiparticle energy gaps of molecular systems weakly coupled to an environment. The approach is applied to C60 adsorbed on Au(111) and Ag(100) surfaces, resulting in electronic structures that are in excellent agreement with recent experiments. Image-charge screening effects on molecular orbital energies are found to be of similar magnitude for the two surfaces, but charge-transfer screening and spin fluctuations also affect the Ag case due to a partially occupied C60 orbital. 相似文献
In flame spray pyrolysis (FSP), the generation of uniform nanoparticles can be quite challenging due to difficulties in controlling droplet sizes during liquid spraying and uneven flame temperature. Here, we report a method to produce relatively uniform nanocrystals of a Tb3+ doped Y2O3 phosphor. In ethanol, metal nitrate precursors were simply mixed with organic surfactants to form a homogeneous solution which was then subjected to FSP. Depending on relative concentrations of the surfactant (oleic acid) to the metal precursors (yttrium and terbium nitrates), different sizes and morphologies of Y2O3:Tb3+ particles were obtained. By adjusting the surfactant concentration, Y2O3:Tb3+ crystals as small as 20~25 nm were acquired. X-ray diffraction and transmittance electron microscopy were used to prove that as-synthesized nanoparticles were highly crystalline due to the high temperature of FSP. X-ray photoelectron spectroscopy revealed that terbium dopants were well distributed throughout Y2O3 particles and a small portion of carbonate impurities were remained on the surface of particles, presumably originated from incomplete combustion of the organic surfactants. Photoluminescence (PL) spectra of Y2O3:Tb3+ nanocrystals exhibited a green light emission ensuring that the terbium doping was successfully occurred. However, when post-annealing was performed on the nanocrystals, their PL was dramatically enhanced indicating that quenching centers such as carbonate impurities and surface defects may have been removed by the annealing process. Owing to the continuous processability of FSP, this current method can be a practical way to produce nanoparticles in a large quantity. The obtained Y2O3:Tb3+ nanocrystals were used to fabricate a transparent film with poly-ethylene-co-vinyl acetate (poly-EVA) polymer, which was suitable for a spectral converting layer for a solar cell.
Hemp (Cannabis sativa L.) contains a variety of secondary metabolites, including cannabinoids, such as psychoactive (−)-trans-Δ⁹-tetrahydrocannabinol. The present study was conducted to identify the major phenolic components contained in hemp root, which has been relatively under-researched compared to other parts of hemp. The aqueous ethanol extract of hemp roots was fractionated into methylene chloride (MC), ethyl acetate (EA), and water (WT) fractions, and high-performance liquid chromatography with photodiode array detection (HPLC-DAD) analysis was performed. The main ultraviolet (UV)-absorbing phenolic compound contained in the EA fraction was identified as p-coumaric acid by comparing the retention time and UV absorption spectrum with a standard. Silica gel column chromatography was performed to isolate a hydrophobic derivative of p-coumaric acid contained in the MC fraction. Nuclear magnetic resonance (NMR) analysis identified the isolated compound as ethyl p-coumarate. For comparative purposes, ethyl p-coumarate was also chemically synthesized by the esterification reaction of p-coumaric acid. The content of p-coumaric acid and ethyl p-coumarate in the total extract of hemp root was estimated to be 2.61 mg g−1 and 6.47 mg g−1, respectively, by HPLC-DAD analysis. These values correspond to 84 mg Kg−1 dry root and 216 mg Kg−1 dry root, respectively. In conclusion, this study identified p-coumaric acid and ethyl p-coumarate as the main phenolic compounds contained in the hemp roots. 相似文献
Journal of Solid State Electrochemistry - Nowadays, metal hexacyanoferrate/metal oxide composites have attracted intense interest as an electrode material for supercapacitor applications due to... 相似文献
Single-atom nanozymes (SAzymes) are promising in next-generation nanozymes, nevertheless, how to rationally modulate the microenvironment of SAzymes with controllable multi-enzyme properties is still challenging. Herein, we systematically investigate the relationship between atomic configuration and multi-enzymatic performances. The constructed MnSA−N3-coordinated SAzymes (MnSA−N3−C) exhibits much more remarkable oxidase-, peroxidase-, and glutathione oxidase-like activities than that of MnSA−N4−C. Based on experimental and theoretical results, these multi-enzyme-like behaviors are highly dependent on the coordination number of single atomic Mn sites by local charge polarization. As a consequence, a series of colorimetric biosensing platforms based on MnSA−N3−C SAzymes is successfully built for specific recognition of biological molecules. These findings provide atomic-level insight into the microenvironment of nanozymes, promoting rational design of other demanding biocatalysts. 相似文献
Mathematical Programming - We introduce and analyze a new family of first-order optimization algorithms which generalizes and unifies both mirror descent and dual averaging. Within the framework of... 相似文献
We defined four major deterioration factors (electrolyte loss (EL), lithium loss (LL), lithium precipitation (LP), and compound deterioration (CD)). Then, we derived eleven key performance indicators (KPIs) for comparative analysis. After that, we fabricated three deteriorated cells for each of three deterioration factors (EL, LL, and LP) and one cell with CD (for verification) with four individual (dis)charging experiment manuals. The two major contributions of this study are the performance of 1) trend analysis to determine a suitable diagnostic metric by inspecting the eleven KPIs and 2) comparison analysis of and to verify the effectiveness of utilizing as a real-time deterioration diagnostic factor using a concept of model-in-the-loop simulation. The results show that 1) has the most conspicuous trendline tendency among the eleven comparison targets for all four major deterioration factors, and 2) the angle difference between the two trends of and lies within a minimum of 9° and a maximum of 43° (with a sscale on the x-axis and a scale on the y-axis for a clear trend line analysis). From this, we can conclude that the trendline-based real-time deterioration analysis employing may be practically applicable to a limited extent. 相似文献
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献