An ultrasensitive nitric oxide (NO) gas sensor based on the graphene oxide (GO)-coated long-period fiber grating (LPFG) was constructed successfully because of its excellent sensitivity to the surrounding refractive index (SRI) change. The surface morphology and structure of GO coated on LPFG were characterized by the scanning electron microscope (SEM), scanning probe microscope (SPM), and Raman spectroscopy, respectively. The adsorption principle of NO molecules by GO was calculated in detail by density functional theory (DFT) and further characterized by Fourier transform infrared spectrometry (FT-TR) and X-ray photoelectron spectroscopy (XPS). Our studies demonstrate that the adsorption principle of NO molecules by GO was the combined effect of physical adsorption and chemical adsorption because of the formation of C-N bonds between GO and NO and the oxidization of NO to NO2. The NO sensor exhibits excellent sensing performance in the NO concentration range of 0 to 400 ppm.
The important measure and key point for Central China Region to grow up is to develop modern logistics industry. Based on actuality analysis of logistics industry in Central China Region, a dynamic feedback causal diagram of logistics in Central China Region is established. The growth mechanism and the growth limits of logistics industry in Central China Region are revealed by using the method of SD feedback analysis and the technology of archetype analysis. The counter measures are put forward to eliminate the growth limits and impel the development of logistics industry in Central China Region.
By using the basic theory and the analysis tool of configuration which is the key outcome of space syntax and by focusing on the space in historic district,this paper deals with the further understanding of typical spatial form from three aspects as follows: how does space possess integration and order,how does space reflect social and cultural information and how does spatial strategy maximize the influence of historic district.By finding the answers to the core issues in this area,the cognizance of space deepens into the level of structure relationship and extends into the reaction with the whole city,which could contribute to the generation of healthy strategies and make people reflect current design trend.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
A nanostructured surface layer was fabricated on 1420 aluminum alloy by high-energy shot peening. Microstructures were characterized by X-ray diffractometer(XRD), transmission electron microscope(TEM) and high-resolution electron microscope ( HRTEM), and microhardness measurement was conducted along the depth from top surface layer to matrix of the sample peened for 30 min. The results show that a nanocrystalline layer about 20 mu m in thickness is formed on the surface of the sample after high-energy shot peening, in which the grain size is changed from about 20 nm to 100 nm. In the surface layer of 20 - 50 mu m in depth, the microstructure consists of sub-micron grains. The surface nanocrystallization is accomplished by dislocation slip. The microhardness of the top surface nanostructured layer is enhanced obviously after high-energy shot peening(HESP) compared with that of the coarse-grained matrix.
Designing a type-I core–shell structure with a shell thickness of >5 nm is the best approach for achieving highly luminescent and stable colloidal quantum dots (QDs). Investigating the temperature-dependent photoluminescence (PL) spectra of these QDs with varying shell thicknesses will help us gain a deeper understanding of how shell thickness influences their diverse optical properties. In this study, we systematically synthesized highly luminescent red- and green-emitting CdxZn1–xS/CdSe/CdyZn1–yS QDs with coherent strained well-type structures featuring varying shell thicknesses. Then, three shell thicknesses of red- and green-emitting QDs with comparable luminescence properties are selected to investigate their photoluminescence properties under temperatures from 80 to 431 K. We find that as the temperature increases, the spectral redshift, broadening, and intensity reduction of the QDs caused by phonon participation are inverse to the shell thickness. Fitting results reveal that a thicker shell weakens electron(exciton)-phonon coupling and increases the exciton binding energy of QDs by isolating the photogenerated excitons away from the inorganic–organic interface. This enables the QDs with a thicker shell to exhibit excellent luminescence efficiency and thermal stability, as evidenced by the stability performance (under varied currents and long-term operation) of photoluminescence white light-emitting diodes based on red- and green-emitting QDs with three different shell thicknesses. Our findings offer an alternative interpretation of the shell thickness-dependent photoluminescence properties of QDs.
Fabrication of nanoscale materials with desirable morphology and surface properties becomes more urgent when constructing hybrid nanocrystals with multiple functionalities. Here, we report a facile measure to control the outer layer growth direction combining with coprecipitation and thermal decomposition method for constructing a series of heterogeneous core/shell structured NaLnF 4 nanocrystals, involving NaYF 4 and NaNdF 4 material. Our investigations suggest that it is feasible to control over the outer layer growth orientation by combining the two traditional methods.
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