Space-air-ground-sea integrated network (SAGSIN), which integrates satellite communication networks, aerial networks, terrestrial networks, and marine communication networks, has been widely ...envisioned as a promising network architecture for 6G. In consideration of its cooperation characteristics of multi-layer networks, open communication environment, and time-varying topologies, SAGSIN faces many unprecedented security challenges, and there have been a number of researches related to SAGSIN security performed over the past few years. Based on such observation, we provide in this paper a detailed survey of recent progress and ongoing research works on SAGSIN security in the aspects of security threats, attack methodologies, and defense countermeasures. To the best of our knowledge, we are the first to present the state-of-the-art of security for SAGSIN, since existing surveys focused either on a certain segment or on several segments of the integrated network, and little can be found on the full coverage network. In addition to reviewing existing works on SAGSIN security, we also present some discussions on cross-layer attacks and security countermeasure in SAGSIN, and identify new challenges ahead and future research directions.
Solar‐driven conversion of CO2 into high value‐added fuels is expected to be an environmental‐friendly and sustainable approach for relieving the greenhouse gas effect and countering energy crisis. ...Metal sulfide semiconductors with wide photoresponsive range and favorable band structures are suitable photocatalysts for CO2 photoreduction. This review summarizes the recent progress on metal sulfide semiconductors for photocatalytic CO2 reduction. First, the fundamentals, mechanisms and some principles, like product selectivity, of photocatalytic CO2 reduction are introduced. Then, according to the elemental composition, the metal sulfide photocatalysts applied for CO2 reduction are classified into binary (CdS, ZnS, MoS2, SnS2, Bi2S3, In2S3,Cu2S, NiS/NiS2, and CoS2), ternary (ZnIn2S4, CdIn2S4, CuInS2, Cu3SnS4, and CuGaS2), and quaternary (Cu2ZnSnS4) systems, in which their crystal structures, photochemical characteristics, and photocatalytic CO2 reduction applications are systematically demonstrated. Especially, the diverse modification strategies for improving the activity and product selectivity of photocatalytic CO2 reduction on these metal sulfides are summarized. Finally, the current challenges and future directions for the development of metal sulfide photocatalysts for CO2 reduction are proposed. This review is expected to serve as a powerful reference for exploiting high‐efficiency metal sulfide photocatalysts for CO2 conversion and furthering related mechanism understanding.
Metal sulfide semiconductors present unique optical/electronic characteristics, which are advantageous for CO2 photoreduction. The advancements in binary, ternary, and quaternary metal sulfide photocatalysts in CO2 photoreduction are elaborately summarized, and the effects of various modification strategies on the reduction activity and product selectivity are highlighted, providing a reference for development of efficient metal sulfides for photocatalytic CO2 reduction to carbonaceous fuels.
With the continuous development of information technology and electronic communications, the problems of electromagnetic interference (EMI) and electromagnetic wave pollution becomes more and more ...serious, and thus the EMI shielding materials have recently attracted numerous attentions. Carbon materials have been deemed as good candidate for novel EMI shielding materials due to their unique properties such as superior conductivity, light weight, stable chemical properties, good thermal properties, environmental friendliness, easy processing, and excellent mechanical properties. And great developments of carbon-based EMI shielding materials have been achieved in the past few years. In the current review article, we mainly focus on the EMI shielding mechanism and EMI shielding performance of various forms of carbon materials. Combining with the current research status, their future development was also prospected.
Display omitted
Semiconductor photocatalysts have important applications in the fields of renewable energy production and environmental remediation. To overcome the drawbacks in the photocatalytic process, such as ...weak photoabsorption, low charge separation efficiency and insufficient surface reactive sites, many strategies have been developed in the past few decades. This review attempts to provide a comprehensive summary and update of some fundamental issues in nanostructure design of graphitic carbon nitride (g-C
3
N
4
). We focus especially on recent progress in designing and fabricating g-C
3
N
4
photocatalysts with various dimensional structures, such as zero-dimensional quantum dots, one-dimensional nanorods and nanotubes, two-dimensional nanosheets, and three-dimensional nanospheres and nanoflowers, identifying the key factors in determining the photocatalytic efficiency, enumerating the wide range of new applications of g-C
3
N
4
photocatalysts, and finally highlighting the crucial issues that should be addressed in the future in the aforementioned interesting research areas.
This review article provides a comprehensive overview of the nanostructure design of g-C
3
N
4
with various dimensional structures and promising applications.
Display omitted
Reduction of CO2 to solar fuels by artificial photosynthesis technology has attracted considerable attention. However, insufficient separation of charge carriers and weak CO2 ...adsorption hamper the photocatalytic CO2 reduction activity. Herein, we tackle these challenges by introducing oxygen vacancies (OVs) on the two-dimensional Bi4Ti3O12 ultrathin nanosheets via a combined hydrothermal and post-reduction process. Selective photodeposition experiment of Pt over Bi4Ti3O12 discloses that the ultrathin structure shortens the migration distance of photo-induced electrons from bulk to the surface, benefiting the fast participation in the CO2 reduction reaction. The introduction of OVs on ultrathin Bi4Ti3O12 nanosheets leads to enormous amelioration on surface state and electronic structure, thereby resulting in enhanced CO2 adsorption, photoabsorption and charge separation efficiency. The photocatalytic experiments uncover that ultrathin Bi4Ti3O12 nanosheets with OVs reveal a largely enhanced CO2 photoreduction activity for producing CO with a rate of 11.7 μmol g−1 h−1 in the gas–solid system, ~3.2 times higher than that of bulk Bi4Ti3O12. This work not only yields efficient ultrathin photocatalysts with OVs, but also furthers our understanding on enhancing CO2 reduction via cooperative tactics.
Photocatalytic CO2 reduction attracts substantial interests for the production of chemical fuels via solar energy conversion, but the activity, stability, and selectivity of products were severely ...determined by the efficiencies of light harvesting, charge migration, and surface reactions. Structural engineering is a promising tactic to address the aforementioned crucial factors for boosting CO2 photoreduction. Herein, a timely and comprehensive review focusing on the recent advances in photocatalytic CO2 conversion based on the design strategies over nano‐/microstructure, crystalline and band structure, surface structure and interface structure is provided, which covers both the thermodynamic and kinetic challenges in CO2 photoreduction process. The key parameters essential for tailoring the size, morphology, porosity, bandgap, surface, or interfacial properties of photocatalysts are emphasized toward the efficient and selective conversion of CO2 into valuable chemicals. New trends and strategies in the structural design to meet the demands for prominent CO2 photoreduction activity are also introduced. It is expected to furnish a comprehensive guideline for inside‐and‐out design of state‐of‐the‐art photocatalysts with well‐defined structures for CO2 conversion.
The advance on CO2 photoreduction based on the design strategies over nano‐/microstructure, crystalline and band structure, surface structure and interface structure for promoting three crucial factors, including light harvesting, charge migration and surface reactions, are systematically summarized. It is expected to furnish a guideline for inside‐and‐out design of photocatalysts with well‐defined structures for CO2 conversion.
Background
Preoperative diagnosis of liver fibrosis in children with pancreaticobiliary maljunction (PBM) is needed to guide clinical decision‐making and improve patient prognosis.
Purpose
To develop ...and validate an MR‐based radiomics‐clinical nomogram for identifying liver fibrosis in children with PBM.
Study Type
Retrospective.
Population
A total of 136 patients with PBM from two centers (center A: 111 patients; center B: 25 patients). Cases from center A were randomly divided into training (74 patients) and internal validation (37 patients) sets. Cases from center B were assigned to the external validation set. Liver fibrosis was determined by histopathological examination.
Field Strength/Sequence
A 3.0 T (two vendors)/T1‐weighted imaging and T2‐weighted imaging.
Assessment
Clinical factors associated with liver fibrosis were evaluated. A total of 3562 radiomics features were extracted from segmented liver parenchyma. Maximum relevance minimum redundancy and least absolute shrinkage and selection operator were recruited to screen radiomics features. Based on the selected variables, multivariate logistic regression was used to construct the clinical model, radiomics model, and combined model. The combined model was visualized as a nomogram to show the impact of the radiomics signature and key clinical factors on the individual risk of developing liver fibrosis.
Statistical Tests
Mann–Whitney U and chi‐squared tests were used to compare clinical factors. P < 0.05 was considered statistically significant in the final models.
Results
Two clinical factors and four radiomics features were selected as they were associated with liver fibrosis in the training (AUC, 0.723, 0.927), internal validation (AUC, 0.718, 0.885), and external validation (AUC, 0.737, 0.865) sets. The radiomics‐clinical nomogram yielded the best performance in the training (AUC, 0.977), internal validation (AUC, 0.921), and external validation (AUC, 0.878) sets, with good calibration (P > 0.05).
Data Conclusion
Our radiomic‐based nomogram is a noninvasive, accurate, and preoperative diagnostic tool that is able to detect liver fibrosis in PBM children.
Evidence Level
3.
Technical Efficacy
Stage 2.
Display omitted
•Two supported microporous carbons on sepiolite was synthesized to activate PMS.•KOH was more effective than ZnCl2 in enhancing PMS activation performance.•TC degradation in SMC-K/PMS ...system follows a non-radical mechanism.•The role of SMC-K in PMS activation for efficient TC degradation was discussed.•TC degradation pathway by non-radical involved oxidation process was proposed.
Carbon-based peroxymonosulfate (PMS) activator as a promising candidate for substituting metal-based heterogeneous catalysts has drawn increasing concerns. In this study, we reported two supported microporous carbon based PMS activators after treatment by KOH and ZnCl2 (denoted as SMC-K and SMC-Z). Their catalytic activity was evaluated and compared by the degradation efficiency of a typical antibiotics of tetracycline (TC). The results indicated that SMC-K exhibited a higher PMS activation performance than SMC-Z. TC degradation data followed the pseudo-first-order kinetics with reaction rate constants of 0.0818 and 0.0392 min−1, respectively. Based on the characterization results, SMC-K had an extensive microporous structure with abundant vacancy defects and catalytic active sites, accompanied by more basic site distribution. The PMS activation mechanism was further explored via quenching tests, electron paramagnetic resonance (EPR) and electrochemical impedance spectroscopy (EIS). TC degradation occurred via a non-radical oxidation mechanism: (1) direct oxidation by activated PMS where SMC-K acted as the electron transfer shuttle, (2) oxidized by 1O2 instead of SO4− or OH generated from PMS self-decomposition. Furthermore, a reasonable degradation pathway of TC based on the non-radical oxidation has been proposed. This work benefits to develop new treatment technologies for organic pollutants removal in practical application.
Epipremnum aureum is an important foliage plant in the Araceae family. In this study, we have sequenced the complete chloroplast genome of E. aureum by using Illumina Hiseq sequencing platforms. This ...genome is a double-stranded circular DNA sequence of 164,831 bp that contains 35.8% GC. The two inverted repeats (IRa and IRb; 26,606 bp) are spaced by a small single-copy region (22,868 bp) and a large single-copy region (88,751 bp). The chloroplast genome has 131 (113 unique) functional genes, including 86 (79 unique) protein-coding genes, 37 (30 unique) tRNA genes, and eight (four unique) rRNA genes. Tandem repeats comprise the majority of the 43 long repetitive sequences. In addition, 111 simple sequence repeats are present, with mononucleotides being the most common type and di- and tetranucleotides being infrequent events. Positive selection pressure on rps12 in the E. aureum chloroplast has been demonstrated via synonymous and nonsynonymous substitution rates and selection pressure sites analyses. Ycf15 and infA are pseudogenes in this species. We constructed a Maximum Likelihood phylogenetic tree based on the complete chloroplast genomes of 38 species from 13 families. Those results strongly indicated that E. aureum is positioned as the sister of Colocasia esculenta within the Araceae family. This work may provide information for further study of the molecular phylogenetic relationships within Araceae, as well as molecular markers and breeding novel varieties by chloroplast genetic-transformation of E. aureum in particular.
PDF
