Facile synthesis of core–shell porous Fe3_{{3}}O4_{{4}}@carbon microspheres with high lithium storage performance

Core–shell porous Fe3O4@C (CP-Fe3O4@C) microspheres were synthesized using an environmentally viable hydrothermal method. Carbonization can reduce Fe2O3 and provide a conductive coating simultaneously. CP-Fe3O4@C microspheres as an active material for Lithium-ion batteries demonstrate pseudocapacity for improved rate performance. With a distinct nanostructure and pseudocapacitive effect, the CP-Fe3O4@C microspheres show excellent electrochemical performance (${\sim }785~\mathrm{mAh}{\cdot }\mathrm{g}^{-1}$ at $0.3~\mathrm{A}{\cdot }\mathrm{g}^{-1}$ after 200 cycles). Capacity measurements of CP-Fe3O4@C microspheres suggest near 90% pseudocapacitance at relatively low scan rates ($5~\mathrm{mV}{\cdot }\mathrm{s}^{-1}$)

Facile synthesis of core–shell porous Fe3_{{3}}O4_{{4}}@carbon microspheres with high lithium storage performance

Core–shell porous Fe3O4@C (CP-Fe3O4@C) microspheres were synthesized using an environmentally viable hydrothermal method. Carbonization can reduce Fe2O3 and provide a conductive coating simultaneously. CP-Fe3O4@C microspheres as an active material for Lithium-ion batteries demonstrate pseudocapacity for improved rate performance. With a distinct nanostructure and pseudocapacitive effect, the CP-Fe3O4@C microspheres show excellent electrochemical performance (${\sim }785~\mathrm{mAh}{\cdot }\mathrm{g}^{-1}$ at $0.3~\mathrm{A}{\cdot }\mathrm{g}^{-1}$ after 200 cycles). Capacity measurements of CP-Fe3O4@C microspheres suggest near 90% pseudocapacitance at relatively low scan rates ($5~\mathrm{mV}{\cdot }\mathrm{s}^{-1}$)

Hyperspectral Imaging for the Nondestructive Quality Assessment of the Firmness of Nanguo Pears Under Different Freezing/Thawing Conditions

Firmness changes in Nanguo pears under different freezing/thawing conditions have been characterized by hyperspectral imaging (HSI). Four different freezing/thawing conditions (the critical temperatures, numbers of cycles, holding time and cooling rates) were set in this experiment. Four different pretreatment methods were used: multivariate scattering correction (MSC), standard normal variate (SNV), Savitzky-Golay standard normal variate (S-G-SNV) and Savitzky-Golay multiplicative scattering correction (S-G-MSC). Combined with competitive adaptive reweighted sampling (CARS) to identify characteristic wavelengths, firmness prediction models of Nanguo pears under different freezing/thawing conditions were established by partial least squares (PLS) regression. The performance of the firmness model was analyzed quantitatively by the correlation coefficient (R), the root mean square error of calibration (RMSEC), the root mean square error of prediction (RMSEP) and the root mean square error of cross validation (RMSECV). The results showed that the MSC-PLS model has the highest accuracy at different cooling rates and holding times; the correlation coefficients of the calibration set (Rc) were 0.899 and 0.927, respectively, and the correlation coefficients of the validation set (Rp) were 0.911 and 0.948, respectively. The accuracy of the SNV-PLS model was the highest at different numbers of cycles, and the Rc and the Rp were 0.861 and 0.848, respectively. The RMSEC was 65.189, and the RMSEP was 65.404. The accuracy of the S-G-SNV-PLS model was the highest at different critical temperatures, with Rc and Rp values of 0.854 and 0.819, respectively, and RMSEC and RMSEP values of 74.567 and 79.158, respectively

Spectral measurement using IC-compatible linear variable optical filter

This paper reports on the functional and spectral characterization of a microspectrometer based on a CMOS detector array covered by an IC-Compatible Linear Variable Optical Filter (LVOF). The Fabry-Perot LVOF is composed of 15 dielectric layers with a tapered middle cavity layer, which has been fabricated in an IC-Compatible process using resist reflow. A pattern of trenches is made in a resist layer by lithography and followed by a reflow step result in a smooth tapered resist layer. The lithography mask with the required pattern is designed by a simple geometrical model and FEM simulation of reflow process. The topography of the tapered resist layer is transferred into silicon dioxide layer by an optimized RIE process. The IC-compatible fabrication technique of such a LVOF, makes fabrication directly on a CMOS or CCD detector possible and would allow for high volume production of chip-size micro-spectrometers. The LVOF is designed to cover the 580 nm to 720 spectral range. The dimensions of the fabricated LVOF are 5×5 mm2. The LVOF is placed in front of detector chip of a commercial camera to enable characterization. An initial calibration is performed by projecting monochromatic light in the wavelength range of 580 nm to 720 nm on the LVOF and the camera. The wavelength of the monochromatic light is swept in 1 nm steps. The Illuminated stripe region on the camera detector moves as the wavelength is swept. Afterwards, a Neon lamp is used to validate the possibility of spectral measurement. The light from a Neon lamp is collimated and projected on the LVOF on the camera chip. After data acquisition a special algorithm is used to extract the spectrum of the Neon lamp

Design and implementation of a sub-nm resolution microspectrometer based on a Linear-Variable Optical Filter

In this paper the concept of a microspectrometer based on a Linear Variable Optical Filter (LVOF) for operation in the visible spectrum is presented and used in two different designs: the first is for the narrow spectral band between 610 nm and 680 nm, whereas the other is for the wider spectral band between 570 nm and 740 nm. Design considerations, fabrication and measurement results of the LVOF are presented. An iterative signal processing algorithm based on an initial calibration has been implemented to enhance the spectral resolution. Experimental validation is based on the spectrum of a Neon lamp. The results of measurements have been used to analyze the operating limits of the concept and to explain the sources of error in the algorithm. It is shown that the main benefits of a LVOF-based microspectrometer are in case of implementation in a narrowband application. The realized LVOF microspectrometers show a spectral resolution of 2.2 nm in the wideband design and 0.7 nm in the narrowband design.MicroelectronicsElectrical Engineering, Mathematics and Computer Scienc