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1.
Small ; 19(16): e2206083, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36683234

RESUMO

The notorious shuttle effect and sluggish conversion of polysulfides seriously hinder the practical application of Lithium-sulfur (Li-S) batteries. In this study, a novel architecture of MoS2 /MoO3 heterostructure uniformly distributed on carbon nanotubes (MoS2 /MoO3 @CNT) is designed and introduced into Li-S batteries via decorating commercial separator to regulate the redox reactions of polysulfides. Systematic experiments and theoretical calculations showed that the heterostructure not only provides sufficient surface affinity to capture polysulfides and acts as an active catalyst to promote the conversion of polysulfides, but also the highly conductive CNT enables rapid electron/ion migration. As a result, Li-S batteries with the MoS2 /MoO3 @CNT-PP separator deliver an impressive reversible capacity (1015 mAh g-1 at 0.2 A g-1 after 100 cycles), excellent rate capacity (873 mAh g-1 at 5 A g-1 ), and low self-discharge capacity loss (94.6% capacity retention after 7 days of standing). Moreover, even at an elevated temperature of 70 °C, it still exhibits high-capacity retention (800 mAh g-1 at 1 A g-1 after 100 cycles). Encouragingly, when the sulfur load is increased to 8.7 mg cm-2 , the high reversible areal capacity of 6.61 mAh cm-2 can be stably maintained after 100 cycles, indicating a high potential for practical application.

3.
Guang Pu Xue Yu Guang Pu Fen Xi ; 35(5): 1248-52, 2015 May.
Artigo em Chinês | MEDLINE | ID: mdl-26415437

RESUMO

Visible near spectra tecnnology was adopted to detect soil total nitrogen content. 394 soil samples were collected from Wencheng, Zhejiang province to be used for calibration model (n=263) and independent prediction set (n=131). Raw spectra and wavelength-reduced spectra with five different pretreatment methods (SG smoothing, SNV, MSC, 1st-D and 2nd-D) were compared to determine the optimal wavelength range and pretreatment method for analysis. The results with 5 different pretreatment methods were not improved compared to that both of full spectra PLS model and wavelength reduction spectra model. Spectral variable selection is an important strategy in spectrum modeling analysis, because it tends to parsimonious data representation and can lead to multivariate models with better performance. In order to simply calibration models, the wavelength variables selected by two different variable selection methods (i. e. regression coefficient analysis (RCA) and successive projections algorithm (SPA) were proposed to be the inputs of calibration methods of PLS, MLR and LS-SVM models separately. These calibration models were also compared to select the best model to predict soil TN. In total, 9 different models were built ahd the best results indicated that PLS, MLR and LS-SVM obtained the highest precision with determination coefficient of prediction R2(pre) =0. 81, RMSEP=0. 0031 and RPD=2. 26 based on wavelength variables selected by RCA (0. 0002) and SPA as inputs of models. SPA-MLR model and other three models based on 7 sensitive variables selected by RC using 0. 0002 regression coefficient threshold value obtained the best result with R2(pre), RMSEP and RPD as 0. 81, 0. 0031 and 2. 26. This prediction accuracy is classied to be very good. For all the models, it could be concluded that RCA and SPA could be very useful ways to selected sensitive wavelengths, and the selected wavelengths were effective to estimate soil TN. It is recommended to adopt SPA variable selection or RCA variable selection method with both linear and nonlinear calibration models for measurement of the soil TN using Vis-NIR spectroscopy technology, and wavelengths selection could be very useful to reduce collinearity and redundancies of spectra.


Assuntos
Nitrogênio/análise , Solo/química , Espectroscopia de Luz Próxima ao Infravermelho , Algoritmos , Análise dos Mínimos Quadrados , Modelos Teóricos , Análise de Regressão
4.
Guang Pu Xue Yu Guang Pu Fen Xi ; 35(7): 1949-55, 2015 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-26717758

RESUMO

Compared with the traditional chemical methods and the subjective visual ways for measuring plant physiology information indicators, the assessments of crop canopy information through spectral radiometer are more simple, rapid and accurate. The applications of different types of spectral radiometer, especially for international general used Cropscan multispectral radiometer, for predicting crop canopy leaf area index under different growth stage, biomass, nitrogen, chlorophyll and yield, and monitoring plant diseases and insect pests were summarized based on crop group information acquisition methods in recent years. The varity of vegetation indices (VIs) were concluded after comparing regression coefficients of related models among different crops. In general, the correlation coefficients of mathematical models were high and it can realize the crop detection of various kinds of physiological information. Besides, the combination of multispectral radiometer and other sensors can provide useful information to evaluate the status of crops growth, which is very important in practice.


Assuntos
Produtos Agrícolas , Folhas de Planta , Análise Espectral/métodos , Biomassa , Clorofila/análise , Monitoramento Ambiental/métodos , Modelos Teóricos , Nitrogênio/análise , Doenças das Plantas
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