The creation of new bonds via C-F bond cleavage of readily available per- or oligofluorinated compounds has received growing interest. Using such a strategy, a myriad of valuable partially ...fluorinated products can be prepared, which otherwise are difficult to make by the conventional C-F bond formation methods. Visible light photoredox catalysis has been proven as an important and powerful tool for defluorinative reactions due to its mild, easy to handle, and environmentally benign characteristics. Compared to the classical C-F activation that proceeds via two-electron processes, radicals are the key intermediates using visible light photoredox catalysis, providing new modes for the cleavage of C-F bonds. In this review, a summary of the visible light-promoted C-F bond cleavage since 2018 was presented. The contents were classified by the fluorosubstrates, including polyfluorinated arenes, gem-difluoroalkenes, trifluoromethyl arenes, and trifluoromethyl alkenes. An emphasis is placed on the discussion of the mechanisms and limitations of these reactions. Finally, my personal perspective on the future development of this rapidly emerging field was provided.
•A decomposed convolutional neural network model was established based on rs-fMRI connectivity.•The model paired with the Dos_160 atlas can be effectively applied to the diagnosis of tinnitus.•This ...study pinpointed key brain regions for subjective tinnitus using a data-driven approach.
Many studies have investigated aberrant functional connectivity (FC) using resting-state functional MRI (rs-fMRI) in subjective tinnitus patients. However, no studies have verified the efficacy of resting-state FC as a diagnostic imaging marker. We established a convolutional neural network (CNN) model based on rs-fMRI FC to distinguish tinnitus patients from healthy controls, providing guidance and fast diagnostic tools for the clinical diagnosis of subjective tinnitus.
A CNN architecture was trained on rs-fMRI data from 100 tinnitus patients and 100 healthy controls using an asymmetric convolutional layer. Additionally, a traditional machine learning model and a transfer learning model were included for comparison with the CNN, and each of the three models was tested on three different brain atlases.
Of the three models, the CNN model outperformed the other two models with the highest area under the curve, especially on the Dos_160 atlas (AUC = 0.944). Meanwhile, the model with the best classification performance highlights the crucial role of the default mode network, salience network, and sensorimotor network in distinguishing between normal controls and patients with subjective tinnitus.
Our CNN model could appropriately tackle the diagnosis of tinnitus patients using rs-fMRI and confirmed the diagnostic value of FC as measured by rs-fMRI.
Purely organic room temperature phosphorescence, especially in aqueous solution, is attracting increasing attention owing to its large Stokes shift, long lifetime, low preparation cost, low toxicity, ...good processing performance advantages, and broad application value. This review mainly focuses on macrocyclic (cyclodextrin and cucurbituril) hosts, nanoassembly, and macromolecule (polyether) confinement-driven RTP. As an optical probe, the assembly and the two-stage assembly strategy can realize the confined purely organic RTP and achieve energy transfer and light-harvesting from fluorescence to delayed fluorescence or phosphorescence. This supramolecular assembly is widely applied for luminescent materials, cell imaging, and other fields because it effectively avoids oxygen quenching. In addition, the near-infrared excitation, near-infrared emission, and
in situ
imaging of purely organic room temperature phosphorescence in assembled confinement materials are also prospected.
Purely organic room temperature phosphorescence, especially in aqueous solution, is attracting increasing attention owing to its large Stokes shift, long lifetime, low preparation cost, low toxicity, good processing performance advantages, and broad application value.
Purely organic room-temperature phosphorescence has attracted attention for bioimaging but can be quenched in aqueous systems. Here we report a water-soluble ultralong organic room-temperature ...phosphorescent supramolecular polymer by combining cucurbitnuril (CB7, CB8) and hyaluronic acid (HA) as a tumor-targeting ligand conjugated to a 4-(4-bromophenyl)pyridin-1-ium bromide (BrBP) phosphor. The result shows that CB7 mediated pseudorotaxane polymer CB7/HA-BrBP changes from small spherical aggregates to a linear array, whereas complexation with CB8 results in biaxial pseudorotaxane polymer CB8/HA-BrBP which transforms to relatively large aggregates. Owing to the more stable 1:2 inclusion complex between CB8 and BrBP and the multiple hydrogen bonds, this supramolecular polymer has ultralong purely organic RTP lifetime in water up to 4.33 ms with a quantum yield of 7.58%. Benefiting from the targeting property of HA, this supramolecular polymer is successfully applied for cancer cell targeted phosphorescence imaging of mitochondria.
Using the social network analysis method, this paper explores the characteristics of the spatial association network structure of China's provincial transportation carbon emissions from 2005 to 2015 ...and its driving factors. The results are as follows: (1) The spatial association of China's provincial transportation carbon emissions exhibits an intuitive network structure. The degree of closeness which were 0.2253 and 0.2333 in 2005 and 2015 respectively shows an increasing trend on the whole. However, it hit the bottom in 2011, reaching a minimum of 0.2230, which is the “low closeness degree inflection point”. (2) The spatial association network presents a significant “core-edge” distribution pattern. Specifically, in the central and eastern regions of China, Henan and Jiangsu have degrees of up to 58.621 and 44.828, which are at the network center. However, some remote regions, like Jilin and Hainan, have degrees of less than 20.000, which are marginalized. (3) The geographical adjacency, the expansion of the difference in R&D investment, and the narrowing of the difference in economic development promote the formation of the interprovincial spatial association. Therefore, in the process of controlling carbon emissions from transportation, the government should focus on the provinces at the network center and pay attention to the impact of the R&D investment on the spatial association of transportation carbon emissions.
•The evolution trend of the spatial association network structure is analyzed.•The “core-edge” distribution of the spatial association network is described.•“Henan is a key governance province” in this study.•“Reducing the R&D investment difference between provinces” is proposed.
Chemical modification of electrode materials by heteroatom dopants is crucial for improving storage performance in rechargeable batteries. Electron configurations of different dopants significantly ...influence the chemical interactions inbetween and the chemical bonding with the host material, yet the underlying mechanism remains unclear. We revealed competitive doping chemistry of Group IIIA elements (boron and aluminum) taking nickel‐rich cathode materials as a model. A notable difference between the atomic radii of B and Al accounts for different spatial configurations of the hybridized orbital in bonding with lattice oxygen. Density functional theory calculations reveal, Al is preferentially bonded to oxygen and vice versa, and shows a much lower diffusion barrier than BIII. In the case of Al‐preoccupation, the bulk diffusion of BIII is hindered. In this way, a B‐rich surface and Al‐rich bulk is formed, which helps to synergistically stabilize the structural evolution and surface chemistry of the cathode.
A model study has been performed on Group IIIA element (boron and aluminum) co‐doped high‐nickel layered oxide cathode materials to understand competitive doping chemistry. A notable difference between the atomic radii of B and Al accounts for different spatial configurations of the hybridized orbital in bonding with lattice oxygen, resulting in the formation of a B‐rich surface and an Al‐rich bulk.
A flexible strain sensor with excellent mechanical and electrical properties was fabricated by depositing carboxylated multiwalled carbon nanotubes (CNTs) and graphene (Gr) onto thermoplastic ...polyurethane (TPU) nanofibrous membranes. The deposition efficiency and fastness of CNTs and Gr particles on TPU nanofibrous membranes were improved by vacuum assisted deposition and ultrasonication. Furthermore, a flexible strain sensor with excellent sensing performance was obtained by optimizing the optimal hybrid ratio between CNTs and Gr. Electromechanical experiments showed that the strain sensor had a wide working range of 172% with a high‐gauge factor of approximately 217 for TPU/5CNTs5Gr composite. Moreover, the TPU/5CNTs5Gr composite also exhibited good durability in 10,000 tensile loading‐unloading cycles, and had superior sensing performance when monitoring the bending motions of human finger, elbow and knee.
As one of the most abundant and highly conserved molecular chaperones, the 70‐kDa heat shock proteins (Hsp70s) play a key role in maintaining cellular protein homeostasis (proteostasis), one of the ...most fundamental tasks for every living organism. In this role, Hsp70s are inextricably linked to many human diseases, most notably cancers and neurodegenerative diseases, and are increasingly recognized as important drug targets for developing novel therapeutics for these diseases. Hsp40s are a class of essential and universal partners for Hsp70s in almost all aspects of proteostasis. Thus, Hsp70s and Hsp40s together constitute one of the most important chaperone systems across all kingdoms of life. In recent years, we have witnessed significant progress in understanding the molecular mechanism of this chaperone system through structural and functional analysis. This review will focus on this recent progress, mainly from a structural perspective.
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