Solar‐energy‐driven CO2 conversion into value‐added chemical fuels holds great potential in renewable energy generation. However, the rapid recombination of charge carriers and deficient reactive ...sites, as two major obstacles, severely hampers the photocatalytic CO2 reduction activity. Herein, a desirable surface halogenation strategy to address the aforementioned concerns over a Sillén‐related layer‐structured photocatalyst Bi2O2(OH)(NO3) (BON) is demonstrated. The surface halogen ions that are anchored on the Bi atoms by replacing surface hydroxyls on the one hand facilitate the local charge separation, and, on the other hand, activate the hydroxyls that profoundly boost the adsorption of CO2 molecules and protons and facilitate the CO2 conversion process, as evidenced by experimental and theoretical results collectively. Among the three series of BON‐X (X = Cl, Br, and I) catalysts, BON‐Br shows the most substantially enhanced CO production rate (8.12 µmol g−1 h−1) without any sacrificial agents or cocatalysts, ≈73 times higher than that of pristine Bi2O2(OH)(NO3), also exceeding that of the state‐of‐the‐art photocatalysts reported to date. This work presents a surface polarization protocol for engineering charge behavior and reactive sites to promote photocatalysis, which shows great promise to the future design of high‐performance materials for clean energy production.
Surface‐halogenation‐induced atomic site activation and local charge separation of layered Bi2O2(OH)(NO3) is presented. Br−‐modified Bi2O2(OH)(NO3) shows the most prominent CO2 activation activity with a CO production rate of 8.12 µmol g−1 h−1, which is 73 times higher than that of bulk Bi2O2(OH)(NO3), exceeding that of most previously reported state‐of‐the‐art photocatalysts.
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A conducting polymer polypyrrole (Ppy) was first employed to decorate BiOI for fabricating an organic-inorganic hybridized Ppy-BiOI nanocomposite photocatalyst via a facile in situ ...precipitation strategy at room temperature. The composite and intimate interface was confirmed by FTIR, XPS, SEM, HRTEM and TEM-mapping. In comparison with pristine BiOI, the Ppy-BiOI hybrids present significantly enhanced photocatalytic activity for degradation of Rhodamine B (RhB) under visible light (λ>420nm). Particularly, the Ppy-BiOI composite exhibits an universal photocatalytic performance for removing diverse industrial pollutants and antibiotics, including bisphenol A, 2,4-dichlorophenol, tetracycline hydrochloride and chlortetracycline hydrochloride. The enhanced photocatalytic activity of Ppy-BiOI composite is found attributable to the bifunctional role that Ppy takes. Ppy-BiOI composite has an enhanced specific surface area, which benefits adsorption and generation of more active sites. Notably, high separation and transfer of the photogenerated charge carriers was achieved on the interface between Ppy and BiOI, and the photogenerated hole transfer action of Ppy is demonstrated. Therefore, synergistic effect of adsorption-enrichment and photocatalytic degradation is realized. Our work may offer a guideline to manipulate high-performance Bi-based composite photocatalyst by coupling conducting polymers.
Through the combination of Bi3+ and a large negative charge ion (BO3)3–, two novel Bi-based borate photocatalysts Bi4B2O9 and Bi2O2BO2(OH) with layered structure have been successfully developed. For ...the first time, the borates were investigated as photocatalysts. They were synthesized by solid-state reaction and hydrothermal method, respectively, and further characterized by XRD, SEM, TEM, HRTEM, and DRS. Bi4B2O9 and Bi2O2BO2(OH) possess direct and indirect transition optical band gaps of 3.02 and 2.85 eV, respectively. Density functional calculations revealed that the valence band (VB) and conduction band (CB) of both borates were composed of hybridized states of the O 2p and Bi 6p or 6s orbitals, and a large dispersion was observed in the energy band of Bi2O2BO2(OH). The photodecomposition experiments demonstrated that Bi4B2O9 and Bi2O2BO2(OH) can be used as effective photocatalysts under simulated solar irradiation, and Bi2O2BO2(OH) exhibits the high photocatalytic activity, which is 2.5 and 3.2 times compared with that of P25 and Bi2O2CO3, respectively. Moreover, the photocurrent conversion further confirmed that Bi4B2O9 and Bi2O2BO2(OH) were potential photofunctional materials. The layered structure with (Bi2O2)2+ layer, hybridized and dispersion energy band, and large negative charge of (BO3)3– ion should be responsible for the high photocatalytic activity of Bi2O2BO2(OH).
This study aimed to evaluate the therapeutic efficacy and effect of blood purification (BP) therapy on severe acute pancreatitis (SAP). Information on 305 patients (BP group 68, control group 237) ...diagnosed with SAP was retrieved from the Medical Information Mart for Intensive Care IV (MIMIC IV) database. Firstly, the influence of BP treatment was preliminarily evaluated by comparing the outcome indicators of the two groups. Secondly, multiple regression analysis was used to screen the mortality risk factors to verify the impact of BP on the survival outcome of patients. Then, the effect of BP treatment was re-validated with baseline data. Finally, cox regression was used to make the survival curve after matching to confirm whether BP could affect the death outcome. The results indicated that the BP group had a lower incidence of shock (p = 0.012), but a higher incidence of acute kidney injury (AKI) (p < 0.001), with no differences observed in other outcome indicators when compared to the control group. It was also found that the 28-day survival curve of patients between the two groups was significantly overlapped (p = 0.133), indicating that BP treatment had no significant effect on the survival outcome of patients with SAP. Although BP is beneficial in stabilizing hemodynamics, it has no effect on short- and long-term mortality of patients. The application of this technology in the treatment of SAP should be done with caution until appropriate BP treatment methods are developed, particularly for patients who are not able to adapt to renal replacement therapy.
Quantifying water inflow information from rock tunnel faces is critical for field engineers to assess the rock mass rating and subsequently make appropriate construction management decisions. This ...paper proposes a novel convolutional neural network (CNN)-based water inflow evaluation method that emulates a typical field engineer's inspection process. It is integrated by a classification step and a semantic segmentation step: the first one is to classify the non-damaged regions and the damaged regions; and the second one is to segment the detailed water inflow damage to the rock tunnel faces. An image database of water inflow in rock tunnel faces was applied for comprehensive training, validation and testing. The experiments on the testing data demonstrate an ideal performance in terms of convergence speed and classification accuracy, as well as quantitative water inflow segmentation. The proposed automatic quantification approach significantly reduces the ergodic damage segmentation procedure through the early exclusion of undamaged samples during the classification process.
•A CNN-based approach emulating the human inspection process was developed.•An image database of water inflow in rock tunnel faces was applied.•Automatic quantification of water inflow information is achieved.•The ergodic segmentation procedure is significantly reduced.
Whole-rock geochemistry and zircon trace element and U-Pb age data for Late Permian–early Middle Triassic volcanogenic sedimentary rocks in SW China show a change from Large Igneous Province to ...subduction-related sources immediately before the Permian–Triassic boundary. Zircons from Late Permian samples give identical within-error ages to the adjoining Emeishan Large Igneous Province (LIP). The bulk-rock geochemistry of these Late Permian units shows no depletion in high field strength elements and is similar to the high-titanium basalts of the Emeishan. Six samples of latest Permian–earliest Triassic tuff and two earliest Middle Triassic tuffs samples yield U-Pb zircon ages at of ~252Ma and ~247Ma, respectively. These tuffs and interstratified volcanogenic sedimentary rocks show significant depletion in high field strength elements, akin to magmatic arc-related rocks. Zircons from the tuffs have Nb/Hf, Th/Nb and Hf/Th ratios similar to those from arc/orogenic-related settings and distinct from the zircons from the Late Permian samples which display within-plate/anorogenic characteristics. Our data demonstrate that there is a compositional change of the volcanogenic sediments across the Permian–Triassic boundary in South China.
► We study the Late Permian-Middle Triassic volcanogenic sediments in SW China. ► A distinct compositional change across the Permo-Triassic boundary was found. ► Source changed from LIP to magmatic arc related volcanic rocks. ► Zircon trace elements are useful provenance indicator.
Current assessments of rock mass quality of a NATM tunnel face are important in the practice of tunnel excavation. This study establishes a multi-source database and proposes a data driven method for ...the assessment. Thirteen multi-source variables describing the tunnel faces are considered as inputs, and the rock mass rating (RMR) values computed by the empirical formula are the target outputs. We adopted two meta machine learning models (classification and regression tree (CART) and multiple layers perceptron (MLP)) and two ensemble learning models (gradient boosting regression tree (GBRT)) and random forest (RF)) to capture the relationships between the inputs and outputs. The tree-structured Parzen estimator (TPE) algorithm is applied to automatically determine the optimized model hyper-parameters. The experimental results suggest that the proposed hybrid ensemble learning models (TPE-RF and TPE-GBRT) perform well at assessing rock mass quality. The feature importance ranks of the input variables are determined by a sensitivity analysis, which enhances the knowledge on assessing the rock mass quality of a tunnel face.
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Over the past few years, silica‐based nanotheranostics have demonstrated their great potential for nano/biomedical applications. However, the uncontrollable and difficult degradability of their pure ...silica framework and long‐time in vivo retention still cause severe and unpredictable toxicity risks. Therefore, it is highly desirable to design and synthesize materials with safer framework structures and compositions. To this aim, the introduction of disulfide bonds into the silica framework can not only maintain high stability in physiological conditions, but also achieve a stimuli‐responsive biodegradation triggered by intracellular reducing microenvironment in living cells, especially in cancer cells. Once nanotheranostics with disulfide (i.e., thioether)‐bridged silsesquioxane framework are taken up by tumor cells via passive or active targeting, the disulfide bonds in the hybrid silica matrix can be cleaved by a high concentration of intracellular glutathione, enabling redox‐triggered biodegradation of the nanosystems for both concomitant release of the loaded therapeutic cargo and in vivo clearance. It is envisioned that such hybrid materials comprised of disulfide‐bridged silsesquioxane frameworks can become promising responsive and biodegradable nanotheranostics. This review summarizes the recent advances in the synthesis of hybrid organosilicas with disulfide‐bridged silsesquioxane frameworks, and discuss their redox‐triggered biodegradation behaviors combined with their biocompatibility and nanobiomedical applications.
An overview of the designed synthesis of nanomaterials consisting of disulfide‐bridged organosilica frameworks, their intracellular redox‐triggered biodegradation behaviors, and emerging nanobiomedical applications is provided in this feature article.
On-site manual inspection of metro tunnel leakages has been faced with the problems of low efficiency and poor accuracy. An automated, high-precision, and robust water leakage inspection method is ...vital to improve the manual approach. Existing approaches cannot provide the leakage location due to the lack of spatial information. Therefore, an integrated deep learning method of water leakage inspection using tunnel lining point cloud data from mobile laser scanning is presented in this paper. It is composed of three parts as follows: (1) establishment of the water leakage dataset using the acquired point clouds of tunnel linings; (2) automated leakage detection via a mask-region-based convolutional neural network; and (3) visualization and quantitative evaluation of the water leakage in 3D space via a novel triangle mesh method. The testing result reveals that the proposed method achieves automated detection and evaluation of tunnel lining water leakages in 3D space, which provides the inspectors with an intuitive overall 3D view of the detected water leakages and the leakage information (area, location, lining segments, etc.).
The damage of lining widely exists in metro shield tunnels, which may weaken the structural performance, affect the durability of the structure and even cause accidents. Investigation and evaluation ...of the lining damage is an essential work to reduce the risk grade during the service life of the structure. A rapid detection and analysis system has been applied in the shield tunnel of Metro Line 2 in Changsha, China for surveying the damage of lining. The system can obtain high definition image information of tunnel surface through multiple array CCD cameras at high speed, and use intelligent analysis method to identify and quantify the damage. The types, morphological characteristics and distribution characteristics of structural damages were analyzed based on the automatic detection results. The causes and the factors influencing the structural damages have been concluded. Finally, the existing problems and development prospects of metro tunnel structure management are discussed from the point of view of construction and maintenance.
•Damage investigation by a rapid detection and intelligent analysis system in Changsha metro is taken as a case study.•The types and distribution characteristics of structural damages are investigated.•The causes and influencing factors of the damages are analyzed.•The existing problems and development trend of tunnel structure maintenance and management are discussed.
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