The antibacterial activity of titanium dioxide nanoparticles (TiO2 NPs) has been extensively documented and applied to food packaging or environmental protection. Ingestion of TiO2 NPs via dietary ...and environmental exposure may pose potential health risks by interacting with gut microbiota. We conducted an animal experiment to investigate the effects of oral exposure to TiO2 NPs on gut microbiota and gut-associated metabolism in Sprague-Dawley rats. Rats were administered with TiO2 NPs (29 ± 9 nm) orally at population-related exposure doses (0, 2, 10, 50 mg kg-1) daily for 30 days. Changes in the gut microbiota and feces metabolomics were analyzed through bioinformatics. TiO2 NPs caused significant changes of colon morphology in rats, manifested as pathological inflammatory infiltration and mitochondrial abnormalities. 16S rDNA sequencing analysis showed that the structure and composition of gut microbiota in rats were modulated after exposure to TiO2 NPs. Monitoring data demonstrated that differentially expressed bacterial strains were obtained until exposure for 14 days and 28 days, including increased L. gasseri, Turicibacter, and L. NK4A136_group and decreased Veillonella. Fecal metabolomics analysis showed that 25 metabolites and the aminoacyl-tRNA biosynthesis metabolic pathway have changed significantly in exposed rats. The increased metabolites were represented by N-acetylhistamine, caprolactam, and glycerophosphocholine, and the decreased metabolites were represented by 4-methyl-5-thiazoleethanol, l-histidine, and l-ornithine. Metabolic disorders of gut microbiota and subsequently produced lipopolysaccharides (LPS) led to oxidative stress and an inflammatory response in the intestine, which was considered to be a key and primary indirect pathway for toxicity induced by oral exposure to the TiO2 NPs. In conclusion, orally ingested TiO2 NPs could induce disorders of gut microbiota and gut-associated metabolism in vivo. The indirect pathway of oxidative stress and inflammatory response, probably due to dysbiosis of gut microbiota primarily, played an important role in the mechanisms of toxicity induced by oral exposure to TiO2 NPs. This may be a common mechanism of toxicity caused by oral administration of most nanomaterials, as they usually have potential antimicrobial activity.
In the present work, Bi3+ was used to substitute for Nd3+ in the NdNbO4 ceramic and pure fergusonite solid solution was formed within 20 mol. % substitutions. Microwave dielectric permittivity of the ...(Nd1‐xBix)NbO4 (x ≤ 0.2) ceramics increased linearly with x value due to the larger ionic polarizability of Bi3+ than Nd3+. Excellent microwave dielectric properties with a permittivity (εr) ~22.5, a Qf (Q = quality factor, f = resonant frequency) ~50 000 GHz, and a TCF ~−9 ppm/°C were obtained in the (Nd0.9Bi0.1)NbO4 ceramic. This method might work in other fergusonite‐type rare‐earth ortho‐niobates.
Temperature coefficient of NdNbO4 microwave ceramic was adjusted to near zero by Bi substitutions.
An environmental management system provides the institutional foundation for sound environmental governance. Conventional environmental management systems, deriving from the combination of the ...vertical management of competent authorities and the localized management of local governments, can lead to local protectionism and implementation deviation at the local level. Since 2016, environmental vertical management reform has been performed as a significant part of the overall promotion of the ecological civilization in China. Representing the most fundamental reform of China’s local environmental management system since the Environmental Protection Law of 1989, the environmental vertical management reform focuses on the reconstruction and adjustment of the environmental management functions among the local governments, and their environment protection authorities at the provincial, city, and county levels. In this paper, we provide an overview of the basic theory of the vertical management model, as well as the motivation for—and the legal/policy background, focuses/content, local practices, and results of—the environmental vertical management reform in China. In the discussion section, we analyze the current problems that impede the effectiveness and sustainability of this reform. On the basis of the analysis of the present and the problems, we raise the question of whether this round of reform is effective and will be sustainable in the future. In response to the challenges, feasible recommendations are proposed. These suggestions include firmly promoting the rule of law in the process of implementing the reform, enhancing the institutional supply and capacity building at the grassroots level, and taking advantage of the holistic governance under the leadership of the Communist Party of China (CPC).
Objectives
This study aimed to explore and validate the value of different radiomics models for differentiating benign and malignant parotid tumors preoperatively.
Methods
This study enrolled 388 ...patients with pathologically confirmed parotid tumors (training cohort:
n
= 272; test cohort:
n
= 116). Radiomics features were extracted from CT images of the non-enhanced, arterial, and venous phases. After dimensionality reduction and selection, radiomics models were constructed by logistic regression (LR), support vector machine (SVM), and random forest (RF). The best radiomic model was selected by using ROC curve analysis. Univariate and multivariable logistic regression was applied to analyze clinical-radiological characteristics and identify variables for developing a clinical model. A combined model was constructed by incorporating radiomics and clinical features. Model performances were assessed by ROC curve analysis, and decision curve analysis (DCA) was used to estimate the models’ clinical values.
Results
In total, 2874 radiomic features were extracted from CT images. Ten radiomics features were deemed valuable by dimensionality reduction and selection. Among radiomics models, the SVM model showed greater predictive efficiency and robustness, with AUCs of 0.844 in the training cohort; and 0.840 in the test cohort. Ultimate clinical features constructed a clinical model. The discriminatory capability of the combined model was the best (AUC, training cohort: 0.904; test cohort: 0.854). Combined model DCA revealed optimal clinical efficacy.
Conclusions
The combined model incorporating radiomics and clinical features exhibited excellent ability to distinguish benign and malignant parotid tumors, which may provide a noninvasive and efficient method for clinical decision making.
Key Points
The current study is the first to compare the value of different radiomics models (LR, SVM, and RF) for preoperative differentiation of benign and malignant parotid tumors.
A CT-based combined model, integrating clinical-radiological and radiomics features, is conducive to distinguishing benign and malignant parotid tumors, thereby improving diagnostic performance and aiding treatment.
Materials exhibiting high energy/power density are currently needed to meet the growing demand of portable electronics, electric vehicles and large-scale energy storage devices. The highest energy ...densities are achieved for fuel cells, batteries, and supercapacitors, but conventional dielectric capacitors are receiving increased attention for pulsed power applications due to their high power density and their fast charge–discharge speed. The key to high energy density in dielectric capacitors is a large maximum but small remanent (zero in the case of linear dielectrics) polarization and a high electric breakdown strength. Polymer dielectric capacitors offer high power/energy density for applications at room temperature, but above 100 °C they are unreliable and suffer from dielectric breakdown. For high-temperature applications, therefore, dielectric ceramics are the only feasible alternative. Lead-based ceramics such as La-doped lead zirconate titanate exhibit good energy storage properties, but their toxicity raises concern over their use in consumer applications, where capacitors are exclusively lead free. Lead-free compositions with superior power density are thus required. In this paper, we introduce the fundamental principles of energy storage in dielectrics. We discuss key factors to improve energy storage properties such as the control of local structure, phase assemblage, dielectric layer thickness, microstructure, conductivity, and electrical homogeneity through the choice of base systems, dopants, and alloying additions, followed by a comprehensive review of the state-of-the-art. Finally, we comment on the future requirements for new materials in high power/energy density capacitor applications.
Due to its excellent physicochemical properties and wide applications in consumer goods, titanium dioxide nanoparticles (TiO
NPs) have been increasingly exposed to the environment and the public. ...However, the health effects of oral exposure of TiO
NPs are still controversial. This study aimed to illustrate the hepatotoxicity induced by TiO
NPs and the underlying mechanisms. Rats were administered with TiO
NPs (29 nm) orally at exposure doses of 0, 2, 10, 50 mg/kg daily for 90 days. Changes in the gut microbiota and hepatic metabolomics were analyzed to explore the role of the gut-liver axis in the hepatotoxicity induced by TiO
NPs.
TiO
NPs caused slight hepatotoxicity, including clear mitochondrial swelling, after subchronic oral exposure at 50 mg/kg. Liver metabolomics analysis showed that 29 metabolites and two metabolic pathways changed significantly in exposed rats. Glutamate, glutamine, and glutathione were the key metabolites leading the generation of energy-related metabolic disorders and imbalance of oxidation/antioxidation. 16S rDNA sequencing analysis showed that the diversity of gut microbiota in rats increased in a dose-dependent manner. The abundance of Lactobacillus_reuteri increased and the abundance of Romboutsia decreased significantly in feces of TiO
NPs-exposed rats, leading to changes of metabolic function of gut microbiota. Lipopolysaccharides (LPS) produced by gut microbiota increased significantly, which may be a key factor in the subsequent liver effects.
TiO
NPs could induce slight hepatotoxicity at dose of 50 mg/kg after long-term oral exposure. The indirect pathway of the gut-liver axis, linking liver metabolism and gut microbiota, played an important role in the underlying mechanisms.
In this study, we have successfully developed the first organocatalytic asymmetric aza‐Henry reaction of dibenzob,f1,4oxazepines as a representative class of unactivated seven‐membered cyclic imines ...with nitroalkanes. In the presence of a Cinchona alkaloid‐based thiourea catalyst, a range of structurally diverse nitrogen‐containing heterocycles were produced in good to excellent yields and enantioselectivities. Furthermore, the ready transformation of the aza‐Henry products into enantioenriched 1,2‐diamine derivatives bode well for the potential applications of this route.
The first organocatalytic asymmetric aza‐Henry reaction of unactivated seven‐membered cyclic imines, dibenzob,f1,4oxazepines, with nitroalkanes has been achieved. In the presence of 10 mol‐% quinine‐derived thiourea, a range of chiral 11‐(nitromethyl)‐10,11‐dihydrodibenzob,f1,4oxazepine derivatives were produced in good to excellent yields (up to 97 %) and enantioselectivities (up to 98 % ee).
This note proposes a zero-gradient-sum method for first-order integrator dynamics that can solve time-varying distributed convex optimization problem in fixed-time. The algorithm is composed of a ...fixed-time sliding mode term for achieving zero-gradient-sum, and a fixed-time controller involving the sign function for attaining state consensus among agents. It requires only local state interaction among neighboring agents, and hence, has lower communication cost. The effectiveness of the algorithm is demonstrated by a power sharing case study.
Ultrahigh discharge energy density ( W dis = 10.5 J cm −3 ) and efficiency ( η = 87%) have been obtained in doped BiFeO 3 –BaTiO 3 ceramic multilayers by achieving an electrically rather than ...chemically homogeneous microstructure. Back scattered scanning and transmission electron microscopy combined with energy dispersive X-ray spectroscopy mapping of (0.7 − x )BiFeO 3 –0.3BaTiO 3 – x Nd(Zn 0.5 Zr 0.5 )O 3 (0.05 ≤ x ≤ 0.10) ceramics revealed a core–shell grain structure which switched from a bright to dark contrast as x increased. Compositions with x = 0.08 were at the point of cross over between these two manifestations of core–shell contrast. Dielectric measurements together with the absence of macrodomains in diffraction contrast TEM images suggested that compositions with x = 0.08 exhibited relaxor behaviour within both the core and shell regions. Impedance spectroscopy demonstrated that, despite being chemical dissimilar, the grains were electrically homogeneous and insulating with little evidence of conductive cores. Multilayers of x = 0.08 had enhanced breakdown strength, E BDS > 700 kV cm −1 and a slim hysteresis loop which resulted in large W dis and high η which were temperature stable to <15% from 25 to 150 °C.
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