Highly Connected Three-Dimensional Covalent Organic Framework with Flu Topology for High-Performance Li-S Batteries.

Lithium-sulfur batteries (LSBs) have been considered as a promising candidate for next-generation energy storage devices, which however still suffer from the shuttle effect of the intermediate lithium polysulfides (LiPSs). Covalent-organic frameworks (COFs) have exhibited great potential as sulfur hosts for LSBs to solve such a problem. Herein, a pentiptycene-based D2h symmetrical octatopic polyaldehyde, 6,13-dimethoxy-2,3,9,10,18,19,24,25-octa(4'-formylphenyl)pentiptycene (DMOPTP), was prepared and utilized as a building block toward preparing COFs. Condensation of DMOPTP with 4-connected tetrakis(4-aminophenyl)methane affords an expanded [8 + 4] connected network 3D-flu-COF, with a flu topology. The non-interpenetrated nature of the flu topology endows 3D-flu-COF with a high Brunauer-Emmett-Teller surface area of 2860 m2 g-1, large octahedral cavities, and cross-linked tunnels in the framework, enabling a high loading capacity of sulfur (∼70 wt %), strong LiPS adsorption capability, and facile ion diffusion. Remarkably, when used as a sulfur host for LSBs, 3D-flu-COF delivers a high capacity of 1249 mA h g-1 at 0.2 C (1.0 C = 1675 mA g-1), outstanding rate capability (764 mA h g-1 at 5.0 C), and excellent stability, representing one of the best results among the thus far reported COF-based sulfur host materials for LSBs and being competitive with the state-of-the-art inorganic host materials.

Piperazine-Linked Metalphthalocyanine Frameworks for Highly Efficient Visible-Light-Driven H2O2 Photosynthesis.

Artificial photosynthesis of H2O2 from O2 reduction provides an energy-saving, safe, and green approach. However, it is still critical to develop highly active and selective 2e- oxygen reduction reaction photocatalysts for efficient H2O2 production owing to the unsatisfactory photosynthesis productivity. Herein, two new two-dimensional piperazine-linked CoPc-based covalent organic frameworks (COFs), namely, CoPc-BTM-COF and CoPc-DAB-COF, were afforded from the nucleophilic substitution reaction of hexadecafluorophthalocyaninato cobalt(II) (CoPcF16) with 1,2,4,5-benzenetetramine (BTM) or 3,3'-diaminobenzidine (DAB). Powder X-ray diffraction analysis in combination with electron microscopy and a series of spectroscopic technologies reveals their crystalline porous framework with a fully conjugated structure and eclipsed π-stacking model. Ultraviolet-visible diffuse reflectance absorption spectra unveil their excellent light absorption capacity in a wide range of 400-1000 nm. This, together with their enhanced photo-induced charge separation and transport efficiency as disclosed by photocurrent response and photoluminescence measurements, endows the as-prepared piperazine-linked CoPc-based COFs with superior photocatalytic activity toward O2-to-H2O2 conversion under visible-light irradiation (λ > 400 nm). In particular, CoPc-BTM-COF exhibits a record-high H2O2 yield of 2096 µmol h-1 g-1 among the COF-based photocatalysts and an impressive apparent quantum yield of 7.2% at 630 nm. The present result should be helpful for fabricating high-performance and low-cost photocatalysts for visible-light-driven H2O2 photosynthesis.

General Design Strategy of Anti-aromatic Porphyrinoids.

A systematic investigation to arrange the typical anti-aromatic porphyrinoids in sequence was performed. Based on density functional theory calculations, six rules are summarized to obtain the high-performance anti-aromatic porphyrinoids: (1) when two atoms are deleted/added on the 18π electron current ring flowing pipe, we will immediately obtain a 16π/20π electron anti-aromatic system; (2) it is a good idea to increase the number of pyrrole/thiophen/furan units on the π-electron current ring flowing pipe; (3) the heteroatom selecting order is -O- (optimal choice), -NH- (second choice), and -S- (last choice); (4) it is worth noting that the C-C=C-C unit is not beneficial for the anti-aromatic properties; (5) it is very significant to avoid the crowded environment in the core space of an anti-aromatic molecule. In this view, -O- is much better than -S- and -NH-; (6) the "circular" skeleton is much better than an "ellipse-like", "rectangular", or "parallelogram-like" one.

AlGaN-based Schottky barrier deep ultraviolet photodetector grown on Si substrate.

This letter reports the influence of material quality and device processing on the performance of AlGaN-based Schottky barrier deep ultraviolet photodetectors grown on Si substrates. The thermal annealing can significantly improve Schottky barrier height and wet chemical etching can effectively remove etching damage. Meanwhile, the decrease of threading dislocation density and the pit size, especially the later, can substantially suppress reverse leakage. As a result, the reverse leakage current density of the as-fabricated deep UV photodetector was reduced down to 3×10-8 A/cm2. Furthermore, the responsivity of the deep UV photodetectors was greatly improved by reducing the point defect concentration.

A Non-targeted Metabolomics Reveals Therapeutical Effect and Mechanism of Sanmiao Pill on Adjuvant-induced Arthritis Rats.

BACKGROUND AND OBJECTIVE: Rheumatoid arthritis (RA) is an increasingly serious disease worldwide that can damage the joints and bones of sufferers. Sanmiao Pill (SMP), a classical traditional Chinese medicine (TCM) prescription, has been used for effective treatments for RA in the clinic. To comprehensively illuminate the therapeutic mechanism of SMP in the treatment of RA, the effects of SMP on biomarkers and metabolic pathways in rats with adjuvant-induced arthritis (AIA) were examined. > Methods: Sprague Dawley rats were randomly divided into two control (CC, Control) groups, two model (MM, Model) groups, a methotrexate group (MTX, 7.6 mg/kg body weight per week), and two SMP groups (San-L, 28.7 mg/kg body weight per day and San-H, 57.4 mg/kg body weight per day). Rats' body weight, paw swelling, arthritis scores, biochemical parameters, histopathology, and so on were used to evaluate the success of the model and the therapeutic effects of SMP. The metabolic techniques were used to characterize the metabolic profile and biomarkers of the serum and urine samples of rats to reveal the metabolic changes that occurred after SMP treatment. > Results: After 21 days of treatment, SMP improved weight gain, reduced the severity of paw swelling, lowered the levels of biochemical indicators (CCP-Ab, IL-6, TNF-α, RF), decreased destruction of articular cartilage and bone erosion, and protected the affected joints.Additionally, 17 and 19 potential biomarkers associated with RA were identified in the serum and urine, respectively. SMP significantly reversed 14 potential biomarkers, such as arachidonic acid, lysoPC(20:4(5Z,8Z,11Z,14Z)), L-tryptophan, 9-cis-Retinoic acid, hippuric acid, pyridoxine, and pantothenic acid. These metabolites are associated with arachidonic acid metabolism, glycerophospholipid catabolism, tryptophan metabolism, phenylalanine metabolism, vitamin B6 metabolism, etc. > Conclusion: These results indicated that RA-related biomarkers reflected the metabolic profile of AIA rats. Meanwhile, SMP could effectively treat RA mainly by reducing inflammation and regulating abnormal lipid metabolic pathways and amino acid metabolisms. It showed that metabolomics could be used to analyze the metabolic profiles involved in RA and reveal the mechanism of SMP treatment of RA.>.

Effect of Thermal Cleaning Prior to p-GaN Gate Regrowth for Normally Off High-Electron-Mobility Transistors.

This work studied the effect of thermal cleaning in metal-organic chemical vapor deposition (MOCVD) prior to p-GaN gate regrowth for normally off high-electron-mobility transistors. X-ray photoelectron spectroscopy, capacitance-voltage measurement, and atomic force microscopy were employed to identify the effects of thermal cleaning before p-GaN regrowth. It was found that the residual damage was hardly repaired at a relatively low thermal cleaning temperature, while GaN decomposition would occur at an excessively high temperature. Thermal cleaning at 850 °C for 2 min in MOCVD can effectively remove the surface contamination and alleviate the etch damage without causing any significant deterioration of the AlGaN barrier. In addition, the density of interface states ( Dit) in the p-GaN gate was reduced from 1012-1013 to 1011-1012 eV-1·cm-2, resulting in a low gate reverse leakage of 0.1 nA/mm @ VDS-OFF = 180 V, a high Ion/ Ioff ratio of 4 × 1010, and a relatively high threshold voltage of +1.7 V @ ID = 10 µA/mm.