Search

Ultra-small carbon quantum dots (s-CQDs) with excitation wavelength-independent fluorescence had been obtained by hydrothermal-followed acid precipitation method and were characterized by FT-IR, TEM, XPS, UV-Vis and XRD. It was found that as-prepared s-CQDs were amorphous spherical particles with an average diameter of 1.51 nm, and there were abundant hydroxyl and carbonyl groups on their surfaces. Moreover, fluorescence emission study found that the luminescence of s-CQDs was aroused by oxygen group decorated on its surface, and the fluorescence properties of s-CQDs were much different from those of large CQDs (l-CQDs), which showed higher quantum yield and better photoluminescence (PL) property than that of l-CQDs. The PL of s-CQDs possessed two emission centers and was exhibited to be excitation independent. When s-CQDs was used as photosensitizer for TiO2 to photocatalytic degradation of methylene blue under visible light irradiation, it showed significantly improved photocatalytic activities compared with 1-CQDs, and the degradation efficiency of methylene blue reached up to 96.6%. The high degradation efficiency was attributed to the ultra-small particle size, abundant acidic groups, and excellent optical properties of s-CQDs. [ABSTRACT FROM AUTHOR]

Objective To study the interventional effect of Yangyin Yiqi Heji (Yin-nourishing Qi-replenishing Mixture) to alveolus epithelial-mesenchymal transition in rats with bleomycin-induced pulmonary fibrosis. Methods Wistar rats in SPF class (n= 120) were randomly divided into normal group, model group, prednisone group and low-dose, mid-dose and high-dose Yangyin Yiqi Heji groups. The rat model of pulmonary fibrosis was copied by using intratracheal instillation of bleomycin, and all groups were orally given corresponding medicinals for 28 d after modeling for 1 d. The rats were executed respectively on the 14th d and 28th d to collect lung samples for detection of left lung pathological changes by using HE and Masson staining. The mRNA expressions of α-smooth muscle actin (α-SMA), E-cadherin, collagen I (Col I) and laminin (LN) were detected in right lung by using real time fluorescence quantitative polymerase chain reaction (RT PCR). Results The mRNA expressions of α-SMA, Col I and LN increased, and E cadherin expressions decreased in model group compared with normal group (P<0.05). After treatment, the mRNA expressions of α-SMA, Col I and LN decreased, and mRNA expression of E cadherin increased in all treatment groups (P <0.05). On the 28th d, mRNA expression of E cadherin increased in high-dose Yangyin Yiqi Heji group compared with prednisone groups (P < 0. 05), and mRNA expression of LN decreased in high dose, mid dose and low-dose Yangyin Yiqi Heji groups (P < 0.05). Conclusion Yangyin Yiqi Heji can inhibit the epithelial-mesenchymal transition in rats with bleomycin-induced pulmonary fibrosis, and the mechanism may be related to down-regulation of genes of α-SMA, Col I and LN and up-regulation of E-cadherin gene. [ABSTRACT FROM AUTHOR]

A series of TixSn1–xO2 (0≤x≤1) solid solution nanocubes wrapped by reduced graphene oxide (TixSn1–xO2/rGO, TSGC) were designed and synthesized for the application exploration as anode material in lithium ion batteries. When graphene oxide (GO) and K2TiO(C2O4)2 (PTO) were mixed in aqueous ambience, the TiO(C2O4)22− ions were not absorbed onto GO surface by the strong electrostatic repulsion force of the similarly negative‐charged surfaces. When Sn4+ ions were added to the mixture, they were easily adsorbed onto the GO surface. At the same time, Sn4+ ions were also easily coordinated by the carboxyl groups of the PTO species. After the followed hydrothermal and heat treatments, the desired 3D nanoarchitecture composites were obtained. Interestingly, in this TixSn1–xO2/rGO series, the Ti0.74Sn0.26O2/rGO sample exhibited the highest specific capacity of 514 mA h g−1 at 0.1 A g−1 even after 1000th cycles (nearly 100 % efficiency). Such promising electrochemical results are attributed to the 3D integrated structure by achieving better electrical contact between the active materials to shorten ion transport pathways, which highlights the synergistic effect from combining the TixSn1–xO2 nanocubes and rGO films. Additionally, the lithium storage mechanism of the as‐prepared TixSn1–xO2/rGO has been studied via in‐situ X‐ray diffraction (XRD) measurements for the first time. A series of cube‐like TixSn1–xO2/rGO composites were fabricated via a facile coordination strategy. When used as anode materials for lithium ion battery, the Ti0.74Sn0.26O2/rGO sample exhibited the high capacity and extremely cycling stability, which highlight its potential applications in energy issues. [ABSTRACT FROM AUTHOR]

• A Bayesian updating framework for dynamic systems is developed based on PCA. • Likelihood function associated with output principal components is constructed. • The key property of the new likelihood function is derived and given in this paper. • New likelihood function can provide equivalent likelihood measures for input samples. • An efficient method combing aBUS and Kriging is proposed to execute the framework. Bayesian updating has been a successful tool for model calibration in uncertainty analysis, especially in reliability analysis. However, Bayesian updating of dynamic systems with high-dimensional output remains challenging work due to the heavy computational burden associated with evaluating a high-dimensional likelihood function. In this case, even the efficient surrogate model methods can fall short of their expected potential. To solve this problem, this paper develops a novel Bayesian updating framework for dynamic systems based on principal component analysis (PCA), which can significantly reduce the output dimension and overcome the "curse of dimension". In the proposed framework, a new likelihood function is constructed based on the low-dimensional output principal components (PCs), and it is analytically proved that the new likelihood function can provide the equivalent likelihood measures to the original one. In this way, any common Bayesian updating method can be applied in the low dimensional PC space by using the new likelihood function. To further improve the efficiency, an efficient Bayesian updating algorithm is proposed in the PCA-based framework, which adopts adaptive Bayesian updating with structural reliability methods (aBUS) and the Kriging model. Finally, four examples are investigated to test the validity of the proposed method. [ABSTRACT FROM AUTHOR]

Soft clay is characterized by high compressibility, low permeability, low strength, and high water content, making it a poor substrate for construction. Hence, soil treatment is often required for soft clay. However, the traditional treatment methods, such as stacking and on-site mixing, involve large space, long time, and high cost. In contrast, lime is stable and cheap, but slow to set and harden. In this paper, the microbially induced carbonate precipitation (MICP) and lime composite curing of soft clay was investigated. Tests were carried out on soft clay samples with different lime ratios. By comparing the changes of strength, composition, and microstructure before and after curing, the mechanism of MICP/lime composite solidification of soft clay was systematically studied. The results showed that (1) a reasonable proportion of lime can react with water and CO2 in clay to generate CaCO3 , and also promote the induction of more CaCO3 precipitation by microorganisms, contributing to the improved strength of solidified clay; (2) MICP/lime composite curing can effectively reduce water in soft clay and help to improve the strength of solidified soil; (3) MICP and lime were complementary in terms of curing time, leading to continuous improvement of curing effect; and (4) the MICP/lime composite has a good effect on the solidification of soft clay. Under the experimental conditions in this study, the best solidification effect was observed for soft clay with a water content of 30% and a lime ratio of 30%. [ABSTRACT FROM AUTHOR]