The recombination of electron–hole pairs severely detracts from the efficiency of photocatalysts. This issue could be addressed in metal–organic frameworks (MOFs) through optimization of the ...charge-transfer kinetics via rational design of structures at atomic level. Herein, a pyrazolyl porphyrinic Ni-MOF (PCN-601), integrating light harvesters, active catalytic sites, and high surface areas, has been demonstrated as a superior and durable photocatalyst for visible-light-driven overall CO2 reduction with H2O vapor at room temperature. Kinetic studies reveal that the robust coordination spheres of pyrazolyl groups and Ni-oxo clusters endow PCN-601 with proper energy band alignment and ultrafast ligand-to-node electron transfer. Consequently, the CO2-to-CH4 production rate of PCN-601 far exceeds those of the analogous MOFs based on carboxylate porphyrin and the classic Pt/CdS photocatalyst by more than 3- and 20-fold, respectively. The reaction avoids the use of hole scavengers and proceeds in a gaseous phase which can take full advantage of the high gas uptake of MOFs. This work demonstrates that the rational design of coordination spheres in MOF structures not only reconciles the contradiction between reactivity and stability but also greatly promotes the interfacial charge transfer to achieve optimized kinetics, providing guidance for the design of highly efficient MOF photocatalysts.
Pure organic materials with intrinsic room‐temperature phosphorescence typically rely on heavy atoms or heteroatoms. Two different strategies towards constructing organic room‐temperature ...phosphorescence (RTP) species based upon the through‐space charge transfer (TSCT) unit of 2.2paracyclophane (PCP) were demonstrated. Materials with bromine atoms, PCP‐BrCz and PPCP‐BrCz, exhibit RTP lifetime of around 100 ms. Modulating the PCP core with non‐halogen‐containing electron‐withdrawing units, PCP‐TNTCz and PCP‐PyCNCz, successfully elongate the RTP lifetime to 313.59 and 528.00 ms, respectively, the afterglow of which is visible for several seconds under ambient conditions. The PCP‐TNTCz and PCP‐PyCNCz enantiomers display excellent circular polarized luminescence with dissymmetry factors as high as −1.2×10−2 in toluene solutions, and decent RTP lifetime of around 300 ms for PCP‐TNTCz enantiomers in crystalline state.
A series of organic phosphors based on paracyclophanes (PCPs) exhibit both strong room‐temperature phosphorescence (RTP) and excellent circularly polarized luminescence. Modulating the PCP core with non‐halogen‐containing electron‐withdrawing units elongates the RTP lifetime to 313.59 and 528.00 ms. The afterglow is visible for several seconds under ambient conditions.
Uncontrolled lithium dendrite growth and dramatic volume change during cycling have long been severely impeding the practical applications of Li metal as the ultimate anode. In this work, ultrathin ...MgF2 nanosheets encapsulated inside nitrogen‐doped graphene‐like hollow nanospheres (MgF2 NSs@NGHSs) are ingeniously fabricated to address these problems by a perfect combination of atomic layer deposition and chemical vapor deposition. The uniform and continuous Li–Mg solid‐solution inner layer formed by the MgF2 nanosheets can reduce the nucleation overpotential and induce selective deposition of Li into the cavities of the NGHSs. Furthermore, the Li deposition behavior and mechanism of the hybrid host are comprehensively explored by in situ optical microscopy at the macroscopic level, in situ transmission electron microscopy at the microscopic level, and theoretical calculations at the atomic level, respectively. Benefiting from a synergistic modulation strategy of nanosheet seed‐induced nucleation and Li‐confined growth, the designed composite demonstrates an endurance of 590 cycles for asymmetric cells and a lifespan over 1330 h for corresponding symmetric cells. When applied in LiFePO4 full cells, it provides a reversible capacity of 90.6 mAh g−1 after 1000 cycles at 1 C.
Ultrathin MgF2 nanosheets encapsulated inside N‐doped graphene‐like hollow nanospheres are prepared by the perfect combination of atomic layer deposition and chemical vapor deposition. In situ optical microscopy, in situ transmission electron microscopy, and theoretical calculations are used to investigate the deposition behavior and mechanism in detail. The Li‐metal batteries based on the designed composite anode demonstrate superior electrochemical performance.
Background
In glioblastoma (GBM), promoter methylation of the DNA repair gene O‐methylguanine‐DNA methyltransferase (MGMT) is associated with beneficial chemotherapy.
Purpose/Hypothesis
To analyze ...radiomics features for utilizing the full potential of medical imaging as biomarkers of MGMT promoter methylation.
Study Type
Retrospective.
Population/Subjects
In all, 98 GBM patients with known MGMT (48 methylated and 50 unmethylated tumors).
Field Strength/Sequence
3.0T magnetic resonance (MR) images, containing T1‐weighted image (T1WI), T2‐weighted image (T2WI), and enhanced T1WI.
Assessment
A region of interest (ROI) of the tumor was delineated. A total of 1665 radiomics features were extracted and quantized, and were reduced using least absolute shrinkage and selection operator (LASSO) regularization.
Statistical Testing
After the support vector machine construction, accuracy, sensitivity, and specificity were computed for different sequences. An independent validation cohort containing 20 GBM patients was utilized to further evaluate the radiomics model performance.
Results
Radiomics features of T1WI reached an accuracy of 67.54%. Enhanced T1WI features reached an accuracy of 82.01%, while T2WI reached an accuracy of 69.25%. The best classification system for predicting MGMT promoter methylation status originated from the combination of 36 T1WI, T2WI, and enhanced T1WI images features, with an accuracy of 86.59%. Further validation on the independent cohort of 20 patients produced similar results, with an accuracy of 80%.
Data Conclusion
Our results provide further evidence that radiomics MR features could predict MGMT methylation status in preoperative GBM. Multiple imaging modalities together can yield putative noninvasive biomarkers for the identification of MGMT.
Level of Evidence: 4
Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:1380–1387.
High-performance multifunctional electromagnetic (EM) materials exhibit great potential for development, and have attracted extensive attention from the scientific field. Generally, the dielectric ..."genes", including conductive networks, interfaces, and defects, are the pivotal factors that determine their performance. Herein, multifunctional Ti3C2Tx@polyaniline decorated MWCNT (TPMC) nanocomposites, containing generous dielectric "genes", were synthesized via the electrostatic self-assembly method. Thanks to the regulation of internal dielectric "genes", TPMC exhibited a tunable EM wave absorption (EMA) and EM interference (EMI) shielding performance. TPMC achieved a maximum reflection loss (RL) of −54.7 dB and an effective absorption bandwidth (EAB) of nearly 6 GHz at 1.5 mm. Moreover, the complete conductive networks endowed TPMC with a reliable EMI shielding capability. It exhibited a maximum EMI shielding effectiveness (SE) of 34 dB, and meanwhile, displayed an absorption-dominated green shielding performance. Furthermore, owing to the integration of the "genes", TPMC showed a high coulomb efficiency (∼98%) and excellent cycling stability (exceeded 95% retation after 8000 cycles), indicating a great potential as outstanding supercapacitor electrode material. This work provides a promising strategy for controlling the EM pollution and alleviating the energy issues.
The Dielectric "genes" are the key core to regulate the multifunction of TPMC, which include defects, interfaces, functional groups and conductive networks. By regulating and patching the dielectric "genes" of TPMC, the multifunctional integration of EM wave absorption, EMI shielding and charge storage can be achieved. Display omitted
In conventional theories, topological band properties are intrinsic characteristics of the bulk material and do not depend on the choice of the reference frame. In this scenario, the principle of ...bulk‐edge correspondence can be used to predict the existence of edge states between topologically distinct materials. In this study, a 2D elastic phononic plate is proposed with a Kekulé‐distorted honeycomb pattern engraved on it. It is found that the pseudospin and the pseudospin‐dependent Chern numbers are not invariant properties, and the ℤ2 number is no longer a sufficient indicator to examine the existence of the edge state. The distinctive pseudospin texture and the pseudomagnetic field are also revealed. Finally, the synthetic helical edge states are successfully devised and experimentally implemented on a dislocation interface connecting two subdomains with bulk pattern identical up to a relative translation. The edge state is also imaged via laser vibrometry.
The topological origin of the “zone‐folding” phononic topological insulator is revealed and its interpretation as an analog to the quantum spin Hall effect is shown to present key differences in comparison with its electronic counterpart. Also, the possibility of realizing two counter‐propagating gapless helical edge states on a dislocation interface connecting two subdomains with bulk pattern identical up to a relative translation is shown.
Fast and efficient cleanup of crude oil spills is still a global challenge because most of the crude oils are highly viscous and lowly fluid. Herein, a kind of polydimethylsiloxane‐decorated wood ...carbon sponges (PDMS@WCS) with desirable compressibility and hydrophobicity for the fast adsorption and enhanced recovery of crude oil via the promotion of Joule‐heating and photothermal effect is reported. Moreover, the PDMS@WCS can be compressed and released at a constant strain of 50% for over times without structural damage due to the protection of PDMS coating. Thus, the adsorbed crude oil can be facilely excluded from PDMS@WCS under external pressure to show enhanced recovery.
Compressible and hydrophobic wood carbon sponges are elegantly fabricated from natural balsa woods and applied for the rapid recovery of high viscosity crude oil via the promotion of Joule‐heating and photothermal effect. Moreover, they possess a vertical porous structure inherited from natural wood that can greatly reduce the transport path of crude oil and increase the oil adsorption rate.
•Precise qualitative and quantitative analysis of phospholipid molecular species.•258 phospholipid molecular species were characterized in 486 human milk samples.•Dynamic changes of classes and sub ...classes of phospholipid over time were analyzed.•Critical change of phospholipid profile between lactation periods were analyzed.
Phospholipids are critical for milk digestion and infant development. But the profile of phospholipid molecular species in human milk and its dynamic changes during the lactation period have never been reported. The present study elucidated precise qualitative and quantitative analysis of 258 phospholipid molecular species in 486 human milk samples. Phosphatidylcholine is the most abundant class, followed by phosphatidylserine, phosphatidylethanolamine and sphingomyelin as the second abundant class in different lactation period. The plasmalogens declined along the lactation period, and the polyunsaturated-phospholipids decreased after 10–15 days. The decrease of phosphatidylcholines and phosphatidylglycerols, and the increase of lysophosphatidylethanolamines and lysophosphatidylcholines are critical changes from 0 to 5 days to 10–15 days; increase of phosphatidylinositols, phosphatidylserines, lysophosphatidylethanolamines and lysophosphatidylcholines is the key changes from 10–15 days to 40–45 days; the decrease of most phospholipid molecular species is the characteristic change from 40–45 days to 200–240 days; and the phospholipid profile achieved stability after 200 days.
Lifting heptagon symbols to functions Dixon, Lance J.; Liu, Yu-Ting
The journal of high energy physics,
10/2020, Letnik:
2020, Številka:
10
Journal Article
Recenzirano
Odprti dostop
A
bstract
Seven-point amplitudes in planar
N
= 4 super-Yang-Mills theory have previously been constructed through four loops using the Steinmann cluster bootstrap, but only at the level of the ...symbol. We promote these symbols to actual functions, by specifying their first derivatives and boundary conditions on a particular two-dimensional surface. To do this, we impose branch-cut conditions and construct the entire heptagon function space through weight six. We plot the amplitudes on a few lines in the bulk Euclidean region, and explore the properties of the heptagon function space under the coaction associated with multiple polylogarithms.
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