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Aromatic polyimide (PI)-based compounds have been widely studied for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) due to their higher specific energy density, economical, environmentally friendly and adjustable redox potential window. However, their solubility in aprotic electrolytes, inherently poor conductivity and low active site utilization limit their application in large-scale energy storage system (ESS). Here, we synthesized two aromatic PI-based conjugated microporous polymers (CMPs) and integrated them with multi-walled carbon nanotubes (CNT) (TAPT-NTCDA@CNT and TAPT-PMDA@CNT) for using as cathode materials for LIBs and SIBs. The aromatic PI-based CMP can effectively utilize the redox activity site due to its abundant π-conjugated redox active units, stable imide bond, high specific surface area and clear pore structure. As expected, the optimum TAPT-NTCDA@CNT exhibits good rate performance (89.7 mAh g−1 at 2000 mA g−1) and long cycle stability (87.3% capacity retention after 500 cycles) in LIBs. Also, TAPT-NTCDA@CNT can provide a higher initial capacity of 91.1 mAh g−1 in SIBs at 30 mA g−1. This work provides key insights for the further development of other new organic electrodes for other advanced rechargeable batteries.

All-inorganic halide perovskite solar cells (PSCs) have acquired great progress, especially CsPbI2Br. However, their photoelectric conversion efficiency (PCE) remains far below the theoretical predictions. Non-radiative recombination is one of the important issues affecting the photoelectric performance of the PSCs, and the defective lead ions derived from the evaporation of halide ions in the inorganic perovskite are the principal non-radiative recombination centers. Herein, the non-radiative recombination is effectively suppressed by introducing the N-methyl-2-pyrrolidone (NMP) as a Lewis base molecule to passivate the defective lead ions. Therefore, by adjusting the dosage of NMP, the smooth and pinhole-free CsPbI2Br perovskite film is obtained and the optimized device exhibits a champion PCE of 16.77% with an excellent fill factor (FF) of 0.80. This work proves the effectiveness of passivation using Lewis base molecules to prevent non-radiative recombination defects in inorganic perovskite.

Reasonable design and construction of electrode materials with high-performance and low-cost are essential for Li-ion batteries (LIBs) and dual-ion batteries (DIBs). Herein, an eco-friendly and facile strategy is proposed to encapsulate Sb2O3 nanoparticles in one-dimensional (1D) multi-nanochannel-containing carbon nanofibers (Sb2O3@MCNF) using the electrospinning method as well as the subsequent calcination. Such unique construction not only effectively reduces the large volume variation during cycling, but also achieves the fast Li+/e− transportation. As a result, the optimized sample with the precursor triphenylantimony (III) content of 0.35 g (Sb2O3@MCNF-0.35) exhibits superior electrochemical performance as anode materials for LIBs and Li-based DIBs (LDIBs), including high reversible capacity (~333.5 mAh g−1 at 1 A g−1 for LIBs and 233.5 mAh g−1 at 0.2 A g−1 for LDIBs) and favorable cycling stability (over 800 cycles for LIBs and 100 cycles for LDIBs). These results demonstrate that the well-designed Sb2O3@MCNF-0.35 can availably boost the electrochemical performance, which provides vast potential for applications in the field of high-performance energy storage equipment.

Dual-ion batteries (DIBs) have attracted immense interest as a new generation of energy storage device due to their low cost, environmental friendliness and high working voltage. However, developing DIBs using organic compounds as active electrode materials is in its infancy. Herein, we first report a bipolar and self-polymerized Cu phthalocyanine (CuTAPc) as an electrode material for sodium-based DIBs (SDIBs). Benefitting from the bipolar property, CuTAPc could serve as the cathode or anode material to construct metal sodium-based or metal sodium-free SDIB (cell 1 or 2) by coupling with sodium anode or graphite cathode, respectively. As a result, cell 1 displays a high discharge capacity of 195.7 mAh g−1 at 50 mA g−1 and a high reversible capacity of 57 mAh g−1 over 2500 cycles at 1 A g−1, and cell 2 shows a high energy density of 324 Wh kg−1 and a high power density of 7481 W kg−1. Subsequently, the proposed binding mechanism and the bipolar reactivity of CuTAPc have been revealed by the detailed reaction kinetic analysis and ex-situ techniques as well as the density functional theory (DFT) calculations. This work could open a pathway to develop the advanced SDIBs constructed by elemental abundant and environmentally friendly organic materials.

Amphichoterpenoids A–C (1–3), unprecedented picoline-derived meroterpenoids possessing a pyrano[3,2-c]pyridinyl-γ-pyranone scaffold, were characterized from the ascidian-derived fungus Amphichorda felina SYSU-MS7908. Their structures were elucidated by spectroscopic methods, X-ray diffraction and electronic circular dichroism (ECD) calculations. A plausible biosynthetic pathway was proposed. The isolated compounds displayed moderate inhibitory activity against acetylcholinesterase with 50% inhibiting concentration (IC50) values of 18.8–53.2 μmol/L.

Organic–inorganic lead halide perovskites have attracted great interest because of their excellent optoelectronic property. The largest problem hindering the real application was degradation due to...

Preserving the functionality of nanosensors is critical for their reliable performance under harsh environmental conditions. Biofunctionalized plasmonic nanostructures are an important class of bionanoconjugates for biosensing, bioimaging, and nanotherapeutics. Plasmonic nanostructures and biomolecules exhibit poor thermal stability over time. Here, we report a class of metal-organic framework, zeolitic imidazolate framework-8 (ZIF-8), as a protective coating for preserving plasmonic nanostructures and plasmonic bionanoconjugates at elevated temperature. Gold nanobipyramids (AuNBPs) with sharp tips are attractive plasmonic nanotransducers with high sensitivity but are prone to structural change and loss of sensitivity. This work reports the first observation that ZIF-8 can preserve the structure of AuNBPs and their corresponding strong electromagnetic field enhancement and high refractive index sensitivity. In addition, ZIF-8 coating enables nearly 100% retention of biorecognition capability of antibodies immobilized on the AuNBP surface after exposure to 60 °C for 48 h. The efficacy, versatility, and facile implementation of ZIF-8 coating offer great promise for the preservation of nanosensors.

Colloidal quantum dots (QDs) containing toxic lead and cadmium compounds, i.e., Pb/Cd(S,Se,Te), have been widely studied for hydrogen generation because of their promising optoelectronic properties and efficient photocatalytic activities. However, it is still desirable to construct heavy-metal-free QDs with high photoconversion efficiencies through careful design and doping with more environmentally benign alternatives. Here, we design and synthesize Cu-doped AgIn5S8 (Cu–AIS) QDs that contain Cu T2 state sites between the Ag 4d and S 3p orbitals, producing adjustable bandgaps and slowing photogenerated charge recombination compared to pristine AIS QDs. We demonstrate that this Cu-doping configuration not only lowers the activation energy barrier with a more negative potential, but it also leads to the efficient separation and transportation of photogenerated electrons and holes. As proof-of-concept, we fabricate a photoelectrochemical (PEC) cell based on a Cu–AIS QD-sensitized TiO2 photoanode and achieve a maximum saturated photocurrent density of ∼9.8 mA cm−2 at 0.75 V versus a reversible hydrogen electrode (RHE). Furthermore, photostability experiments demonstrate that the operational long-term stability of the Cu–AIS QDs is much better than that of an AIS QD-based PEC cell. Overall, heavy-metal-free Cu–AIS QDs pave the way to the design and synthesis of environmentally friendly, high-efficiency, and cost-effective PEC systems for solar-driven hydrogen generation, and other optoelectronic devices, such as photovoltaics and photodetectors.

We present fully polynomial-time (deterministic or randomised) approximation schemes for Holant problems, defined by a non-negative constraint function satisfying a generalised second order recurrence modulo a couple of exceptional cases. As a consequence, any non-negative Holant problem on cubic graphs has an efficient approximation algorithm unless the problem is equivalent to approximately counting perfect matchings, a central open problem in the area. This is in sharp contrast to the computational phase transition shown by 2-state spin systems on cubic graphs. Our main technique is the recently established connection between zeros of graph polynomials and approximate counting. We also use the "winding" technique to deduce the second result on cubic graphs.

Ascidian-derived microorganisms are a significant source of pharmacologically active metabolites with interesting structural properties. When discovering bioactive molecules from ascidian-derived fungi, two new phenols, roussoelins A (1) and B (2), and ten known polyketides (3–12) were isolated from the ascidian-derived fungus Roussoella siamensis SYSU-MS4723. The planar structure of compounds 1 and 2 was established by analysis of HR-ESIMS and NMR data. The conformational analysis of the new compounds was assigned according to coupling constants and selective gradient NOESY experiments, and absolute configurations were completed by the modified Mosher’s method. Among the isolated compounds, 1, 2, and 9 showed moderate antioxidant capacity. Graphical abstract

Metal phthalocyanine-linked conjugated microporous polymers (MPc-CMPs) have huge potential applications in energy conversion and storage systems. However, the inherent low conductivity limits their practical application. Herein, the MPc-CMPs are hybridized with highly conductive carbon nanotubes (CNTs) via the easy vacuum filtration method. Interestingly, the composite (denoted as CoPc-CMP/CNTs) shows the flexible feature, which can be served as the flexible binder-free electrode for supercapacitors (SCs). As expected, the flexible CoPc-CMP/CNTs exhibits a high specific capacitance of 289.1 F g−1 at a current density of 1 A g−1 and good capacity retention of 82.4% over 1350 cycles at a high current density of 10 A g−1. Furthermore, First-principle calculations are used to elucidate the superiority of CoPc-CMP to other analogues. The good electrochemical performance could be attributed to the synergistic effect from the high pseudocapacitance and good conductivity of CoPc-CMP as well as the capacitive contribution and good conductivity of CNTs. Our strategy provides a new avenue to develop the high-performance SCs via rational integration of MPc-CMPs with highly conductive CNTs.

We give a fully polynomial-time randomised approximation scheme (FPRAS) for the number of bases in a bicircular matroids. This is a natural class of matroids for which counting bases exactly is #P-hard and yet approximate counting can be done efficiently., Comment: v3: updated introduction and a slightly better run-time bound. v4: minor revisions; this version is accepted for publication in Combinatorics, Probability and Computing (CPC)

Point-of-care biosensors are critically important for early disease diagnosis and timely clinical intervention in resource-limited settings. The real-world application of these biosensors requires the use of stable biological reagents and cost-effective fabrication approaches. To meet these stringent requirements, we introduce a generic encapsulation strategy to realize ultrastable plasmonic bioink by encapsulating antibodies with an organosiloxane polymer through in situ polymerization. Plasmonic nanostructures serve as sensitive nanotransducers, allowing for label-free biochemical detection. The plasmonic bioink with encapsulated antibodies exhibits excellent thermal, biological, and colloidal stabilities making it compatible with printing process. As a proof-of-concept, we demonstrate the printability of the ultrastable plasmonic bioinks on different types of substrates with direct writing techniques. The organosiloxane polymer preserves the biorecognition capabilities of the biosensors under harsh conditions, including elevated temperature, exposure to chemical/biological denaturants, and ultrasonic agitation. Plasmonic biochips fabricated with the ultrastable ink exhibit superior stability compared to the biochips with unencapsulated antibodies.

Ammonia (NH3) is an atmospheric contaminant contributing to the formation of fine particles, e.g., particulate matter (PM2.5), which induces respiratory diseases. In the atmosphere, horizontal NH3 levels in the stratosphere, middle-upper troposphere, and planetary boundary layer have been studied using surface monitoring and satellite data, yet NH3 vertical distribution above the planetary boundary layer within the lower troposphere is poorly known. In particular, vertical NH3 data would provide information on the role of NH3 in secondary aerosol formation in the lower troposphere. Here, two NH3 profiles on September 2 and 3, 2017, were obtained by in situ aircraft measurement, plus temperature, dew point temperature, and relative humidity over the North China Plain. We also used synoptic analysis and WRF-CHEM modeling. We observed one pollution layer from 2800 to 3500 m on September 2, and two pollution layers, 1750–2250 m and 2500–3450 m, on September 3. Results show that the highest NH3 concentration above the planetary boundary layer was 28.0 ppb at 2500–3450 m over Baoding, comparable to that observed in the planetary boundary layer, of 33.1 ppb, on September 3, 2017. The transport of clean air masses from the northwest of China led to a sharp decrease in NH3 concentration between 2300 and 2800 m and highlighted a relatively high NH3 concentration of 20.0 ppb at approximately 3000 m, which led to the formation of an elevated pollution layer on September 2. The highest pollution layer of 28.0 ppb at 2500–3450 m on September 3, 2017, appears to be driven by the westerly wind, whereas the lower pollution layer of 20.1 ppb at 1750–2250 m was influenced by both local pollutants of the North China Plain and a vertical entrainment effect.

Dolostones are widely developed in the middle Permian rocks of East Yunnan, China, mainly in the shoal-facies Maokou Formation. The previously reported dolostone formation mechanisms cannot explain the distribution and geochemical characteristics of these dolostones, in particular their strontium, magnesium and oxygen isotope signatures. To help predict the distribution of dolostone reservoirs and reduce the exploration risk and cost, this study proposes a new model of dolomitization: open thermal convection dolomitization. In this new dolomitization model, Mg2+ in dolomitizing fluids originates mostly from seawater, with a minor component coming from deep hydrothermal fluids. Elevated heat flux (in this case due to the nearby Emei mantle plume) causes spatial temperature variations in the fluid along the circulation flow pathways, resulting in fast and pervasive dolomitization of limestone. The proposed model not only explains the characteristics and distribution of dolostones in the study area but also serves as a reference for predicting the distribution of dolostones in other areas subjected to thermal convection.

The reasonable design and construction of non-precious metal electrocatalysts with low cost and high performance is critical for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Herein, a facile polymerization-pyrolysis method is proposed to encapsulate Co2P nanoparticles in co-doped hollow carbon shell by using ZIF-67 and P-containing polymers as precursor. The unique construction not only effectively prevents nanoparticles from detaching, showing good stability after long-term testing, but also provides abundant active sites, large surface areas and large pore volumes, enabling the electrolyte and electrode material to full contact. As expected, the Co2P/NPSC-800 performs superior HER performance with low overpotential of 173 mV at 10 mA cm−2 and excellent stability of 88% retention for 35 h and OER performance with low overpotential of 320 mV at 10 mA cm−2, which endows Co2P/NPSC-800 with good catalytic activity in overall water splitting. Furthermore, density functional theory (DFT) calculations reveal that the metallic property and the decreased reaction barriers of Co2P can promote the catalytic reactions. This work offers an effective route in synthesizing other transition metal phosphides with high catalytic properties.

Conjugated microporous polymers (CMPs) as emerging porous materials with diverse structures and tunable building-units have attracted much attention in the electrochemical field. Herein, we designed phthalocyanine-porphyrin-based conjugated microporous polymers as precursors for fabrication of Co, Fe, N tri-doped graphene composites towards oxygen reduction and evolution reaction (ORR/OER). As expected, the elements cobalt and iron are well dispersed in graphene carbon and interact with the nitrogen sites, thereby providing extra electrocatalytic active sites and enhancing its overall conductivity. Benefiting from its unique design and structure, the obtained catalyst affords a superior bifunctional catalytic activity with a positive onset potential of 0.957 V for ORR, and a low overpotential of 0.36 V for OER. More attractively, the CoFeNG is employed as an air cathode catalyst in Zn-air batteries, showing a maximum current density of 215 mA cm-2 and good cycle stability for 20000 s. The rational design of phthalocyanine-porphyrin-based derivatives provides a feasible route for the construction of high-performance ORR/OER catalysts.

As a superstars of photovoltaic devices, organic–inorganic hybrid perovskite solar cells (PSCs) have garnered plenty of interest due to their superior character. However, many defects, such as carr...

Covalent organic polymers (COPs) provide an interesting platform for constructing the low-cost and highly efficient multifunctional electrocatalysts in view of their tailorable structures and prope...

The lithium/sodium-ion storage properties of transition metal oxides often undergo startling volume variation and poor electrical conductivity. Herein, N, P and S doped dual carbon-confined Fe3O4 nanospheres (Fe3O4@C@G) are prepared by the multi-heteroatom-doped dual carbon-confined strategy. The first carbon layer results from multi-heteroatom-containing polymer derived N, P and S doped carbon to form Fe3O4@doped carbon core-shell nanostructure. And the second carbon layer results from the further encapsulated reduced graphene oxide (rGO) to form Fe3O4@doped carbon@graphene 3D architecture (Fe3O4@C@G). As expected, the resulting Fe3O4@C@G can be served as the universal anode materials towards lithium/sodium-ion batteries (LIBs/SIBs). Interestingly, Fe3O4@C@G delivers higher reversible capacity of 919 mAh g−1 at 0.1 A g−1 for LIBs. As for SIBs, Fe3O4@C@G also shows a high reversible capacity of 180 mAh g−1 after 600 cycles at 0.1 A g−1. Furthermore, the electrochemical reaction kinetics in LIBs/SIBs are investigated and Li+ full cells are also assembled to demonstrate its practical application.

In a covariant quark-diquark model, we investigate the rare decay of $\Lambda_b \rightarrow n l^+ l^-$ and $\Lambda_b \rightarrow n \gamma$ in the Bethe-Salpeter equation approach. In this model the baryons are treated as bound states of a constituent quark and a diquark interacting via a gluon exchange and the linear confinement. We find that the ratio of form factors $R$ is varies from $-0.90$ to $-0.25$ and the branching ratios $Br(\Lambda_b \rightarrow n l^+ l^-)\times 10^{8}$ are $6.79(l=e),~4.08 ~ (l=\mu),~2.9 ~(l=\tau) $ and the branching ratio $Br(\Lambda_b \rightarrow \gamma)\times 10^{7} )=3.69$ in central values of parameters., Comment: arXiv admin note: text overlap with arXiv:1911.08023

Conjugated carbonyl compounds have received much attention as cathode materials for developing green lithium-ion batteries (LIBs). However, their high dissolution and poor electronic conductivity in organic electrolyte restrict their further application. Herein, a self-polymerized nitro-substituted conjugated carbonyl compound (2,7-dinitropyrene-4,5,9,10-tetraone, PT-2 NO2 ) is applied as a high-performance cathode material for LIBs. PT-2 NO2 exhibits a high reversible capacity of 153.9 mAh g-1 at 50 mA g-1 after 120 cycles, which is higher than that of other substituted compounds. Detailed characterization and theoretical calculations have testified that PT-2 NO2 is transformed into an azo polymer through an irreversible reductive coupling reaction in the first discharge process, and then carbonyl and azo groups reversibly react with Li ions in subsequent cycles. In addition, this azo polymer is also synthesized and applied as the electrode material, which shows similar electrochemical performance to PT-2 NO2 but with higher initial coulombic efficiency. Thus, this work provides a simple but effectively way to construct organic cathode materials with multiple redox sites for green and high-performance LIBs.

Nickel nitride (Ni3N) is a superior hydrogen evolution reaction (HER) catalyst where the nitrogen source is usually ammonia and the reaction temperature is high during the synthesis process. Herein, we employed an innovative method to obtain three-dimensional porous nickel nitride nanosheets on Ni foam (Ni3N/NF) by transforming Ni(OH)2 nanosheets in N2-H2 glow discharge plasma. The obtained Ni3N/NF displays a high HER activity with a small overpotential of 44 mV and a low Tafel slope of 46 mV dec-1, which is competitive to a Pt/C catalyst. Both the test data and simulation results prove that active ions and radicals in plasma play essential roles in achieving the facile nitridation, as well as building a nanostructured morphology over the Ni3N/NF surface. The unique synthesis method opens new avenues for metal nitrides of HER catalysts and beyond.

Purple sweet potato is known as a rich source of protein and anthocyanins. Anthocyanins can form complexes with protein present in food products through non-covalent forces or covalent bonds during processing, transportation, and storage as their protein affinity. We evaluated the hypoglycemic effects of protein-bound anthocyanin compounds of purple sweet potato (p-BAC-PSP) and free anthocyanin compounds of purple sweet potato (FAC-PSP) in high-fat diet/streptozotocin-induced diabetic mice. The results showed that administration of both p-BAC-PSP and FAC-PSP improved diabetic condition, as evidenced by the improvement of glucose tolerance and lipid metabolism, and the decrease of oxidative stress and liver damage. For the mechanism study, we have found that p-BAC-PSP and FAC-PSP induced the expression of AMP-activated protein kinase in liver. With p-BAC-PSP or FAC-PSP treatment, glucose transporter type 2, the protein levels of glucokinase, and insulin receptor α were found to be improved significantly (p < 0.05). Glycolysis key genes, phosphofructokinase and pyruvate kinase, were upregulated in two treatment groups, while gluconeogenic genes, glucose-6-phosphatase and phosphoenolpyruvate carboxykinase, were downregulated. Our findings suggested that p-BAC-PSP has great potential as a dietary supplement with hypoglycemic activity for general, pre-diabetic, and diabetic population.

It has been a major challenge to dispose the unrenewable high-performance polymers (HPPs) after their large-scale application in our society. Here we report an approach to reuse one kind of HPP as carbon and sulfur sources in synthesizing nitrogen and sulfur dual-doped honeycomb-like porous carbon catalysts for oxygen reduction reaction. Briefly, poly(phenylene sulfide sulfone) with S atoms in polymer chain as sulfur source, dicyandiamide as nitrogen source and SiO2 nanoparticles as hard-template are pyrolyzed in designed temperatures under argon atmosphere. Then N, S dual-doped carbon catalysts (N, S@C) are obtained after subjected etching treatment. By adjusting moderate amount of SiO2, the optimized catalyst (denoted as N, S@CM-1000) pyrolyzed at 1000 °C, shows best ORR electrocatalytic activity in alkaline environment. Impressively, when N, S@CM-1000 is used as a cathode catalyst, the corresponding assembled zinc-air batteries exhibit a maximum power density of 90 mW cm−2 with long-term durability and high rate capacity. Therefore, this work provides a feasible way to resolve and reuse the unrenewable HPP for synthesizing heteroatom doped carbon-based catalysts.

Phosphorus is a promising anode material for lithium ion batteries, while it suffers from poor electronic conductivity and large volume change during operation. These drawbacks can be effectively overcome by replacing P with Cu3P, in which Cu serves as a conductive buffer. However, this strategy will cause significant capacity loss due to inclusion of inert Cu. In this work, we use plasma activated phosphorus vapor to deposit P on a Cu current collector, which converts the surface of the Cu into Cu3P in situ. In this case, the P electrode is converted to a Cu3P electrode without an external Cu source except for the current collector. The high chemical reactivity of plasma allows phosphorization at only 200 °C, leading to a monolithic electrode with excellent mechanical strength and free of any conductive additive and binder. The obtained electrode exhibits a high initial coulombic efficiency of >90%. The areal capacity is up to 2.3 mA h cm−2 after 50 cycles at 3.2 mA cm−2.

The development of bimetallic-based ternary materials (BTMs) has attracted much attention due to their multi-component flexibility and synergistic effect. Herein, BTM (Ce2Sn2O7) nanoparticles are encapsulated into graphene (Ce2Sn2O7/RGO), which served as a novel anode material for lithium-ion batteries and capacitors (LIBs/LICs). Benefiting from the synergistic effects from two metal elements and the conductive networks of graphene, the optimized Ce2Sn2O7/RGO delivers a reversible capacity of 814.6 mA h g−1 at 0.05 A g−1, good cycling performance with a reversible capacity of 369.5 mA h g−1 after 1500 cycles at 1 A g−1 and a superior rate capability of 432.4 mA h g−1 at 2 A g−1 in Li+ half cells. Meanwhile, the detailed phase transition and kinetics analysis as well as the theoretical calculation are performed to investigate the reaction mechanisms behind the good electrochemical performance. Furthermore, the Ce2Sn2O7/RGO also shows good lithium-ion full cell and capacitor performances coupled with commercial LiCoO2 and activated carbon, respectively, which further demonstrates the application prospect of Ce2Sn2O7/RGO.

Extensive efforts have been devoted to develop bifunctional oxygen catalysts for rechargeable zinc–air batteries (ZABs) owing to the extremely high specific energy density, low cost and safety of these emerging batteries. The oxygen catalysts play roles in maximizing the energy conversion efficiencies of ZABs. Herein, a strategy of electronic structure modulation is used by ruthenium doping and post-oxidation treatment in cobalt encapsulated N-doped carbon nanotubes for enhancing catalytic activities of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). First principles calculations reveal that doping Ru into Co or CoOx enhances charge transfer from Ru to carbon atoms adjacent to the doped N atom and then promotes the reversible oxygen reactions. The achieved catalysts (denoted as RuCoOx@Co/N-CNT) exhibit efficient catalytic activities driving both ORR and OER with a small overpotential gap (EOER − EORR = 0.79 V). Specifically, the ZABs assembled with RuCoOx@Co/N-CNT catalysts display an open-circuit potential of 1.44 V, a specific capacity of 788 mA h g−1, a power density of 93 mW cm−2 and long-term discharge–charge cycling stability, even superior to those of commercial Pt/C and RuO2 electrodes. This work proves that modulating the electronic structure of active sites by doping or post oxidation treatment is an efficient way to improve the catalytic performance.

Colloidal quantum dot (CQD) based photoelectrochemical cells (PECs) for solar-driven hydrogen (H2) generation offer an avenue to convert solar energy into chemical fuel. So far, recent advances in CQD-based PEC performance have relied on the use of defect passivation strategies. Specifically, shell-isolated defect passivation in ternary I–III–VI CQDs has been shown to contribute to lowered trap state densities, strengthened effective charge separation, and improved photovoltaic performance. Here we present a kind of heavy metal-free Cu-doped AgIn5S8/ZnS (CAIS/ZnS) core/shell CQD that shows a remarkable photocatalytic efficiency with an engineered shell thickness. In particular, we add a capping ZnS layer to protect the CAIS/ZnS CQD surface in photoanodes and thus enable a dual defect passivation strategy based on the homojunction combination. This strategy passivates surface defects and enhances photogenerated charge transportation in order to maintain high catalytic efficiency, and the additional ZnS layer suppresses energy transfer and nonradiative recombination for better charge injection and greater stability performance of PEC devices. As a result, we achieved a saturated photocurrent density of 23.40 mA cm−2 for a CAIS/ZnS CQD-based PEC measured at 0.75 V versus RHE under 3 suns (that is 3 times the standard solar irradiance of 100 mW cm−2), as compared to 10.60 mA cm−2 under 1 sun, which is a record for heavy metal-free CQD-based photoelectrodes for solar driven hydrogen generation. Importantly, our PEC devices maintained over 50% of their original photocurrent density after 6800 s of aging under 1 sun at 0.5 V versus RHE. Our work reveals a new platform for the development of high-efficiency photocatalysts based on I–III–VI CQDs.

Thiopeptides, which are a class of sulfur-rich, ribosomally synthesized and post-translationally modified peptides (RiPPs), have great potential in the treatment of diseases caused by oral pathogens. Nocathiacin I (NOC-I) and nosiheptide (NOS) are two structurally similar thiopeptide members that feature an indolic side ring. In the structure of NOC-I, this side ring is further rigidified through the formation of an ether linkage; however, the related biosynthetic process remains poorly understood. Here, we report that NocV, a cytochrome P450 protein found to be unique in the biosynthetic pathway of NOC-I, is responsible for the establishment of the intramolecular ether linkage through two oxidation steps. This observation benefited from the heterologous overexpression of the gene nocV in an engineered Streptomyces strain producing the bicyclic NOS intermediate NOS1260, and subsequent isolation and structure characterization of two functionalized products. The product NOS-V1 contains a new hydroxyl group at Cα of the residue Glu6, in contrast with the other product NOS-V2, in which this hydroxyl group is further coupled with the C4 methyl group of the indolic moiety to form an ether linkage. These findings provide insights into the catalytic logic of NocV in the biosynthesis of NOC-I, during which this cytochrome P450 protein appears to act in tandem on two positions in NOS1260 by selectively hydroxylating Glu6 and then oxidatively coupling the indolic moiety. Rigidifying the side ring via ether bond formation has a positive impact on the antibacterial properties of NOS-type thiopeptides, evidenced by the improved activity of NOC-V2 against various tested oral pathogens compared with NOS1260.

We prove a complexity classification for Holant problems defined by an arbitrary set of complex-valued symmetric constraint functions on Boolean variables. This is to specifically answer the question: Is the Fisher-Kasteleyn-Temperley (FKT) algorithm under a holographic transformation (Valiant, SIAM J. Comput. 37(5), 1565–1594 2008) a universal strategy to obtain polynomial-time algorithms for problems over planar graphs that are intractable on general graphs? There are problems that are #P-hard on general graphs but polynomial-time solvable on planar graphs. For spin systems (Kowalczyk 2010) and counting constraint satisfaction problems (#CSP) (Guo and Williams, J. Comput. Syst. Sci. 107, 1–27 2020), a recurring theme has emerged that a holographic reduction to FKT precisely captures these problems. Surprisingly, for Holant, we discover new planar tractable problems that are not expressible by a holographic reduction to FKT. In particular, a straightforward formulation of a dichotomy for planar Holant problems along the above recurring theme is false. A dichotomy theorem for #CSPd, which denotes #CSP where every variable appears a multiple of d times, has been an important tool in previous work. However the proof for the #CSPd dichotomy violates planarity, and it does not generalize to the planar case easily. In fact, due to our newly discovered tractable problems, the putative form of a planar #CSPd dichotomy is false when d ≥ 5. Nevertheless, we prove a dichotomy for planar #CSP2. In this case, the putative form of the dichotomy is true. (This is presented in Part II of the paper.) We manage to prove the planar Holant dichotomy relying only on this planar #CSP2 dichotomy, without resorting to a more general planar #CSPd dichotomy for d ≥ 3. A special case of the new polynomial-time computable problems is counting perfect matchings (#PM) over k-uniform hypergraphs when the incidence graph is planar and k ≥ 5. The same problem is #P-hard when k = 3 or k = 4, which is also a consequence of our dichotomy. When k = 2, it becomes #PM over planar graphs and is tractable again. More generally, over hypergraphs with specified hyperedge sizes and the same planarity assumption, #PM is polynomial-time computable if the greatest common divisor (gcd) of all hyperedge sizes is at least 5. It is worth noting that it is the gcd, and not a bound on hyperedge sizes, that is the criterion for tractability.

To overcome the current limitations of chemodynamic therapy (CDT), a Mo2 C-derived polyoxometalate (POM) is readily synthesized as a new CDT agent. It permits synergistic chemodynamic and photothermal therapy operating in the second near-infrared (NIR-II) biological transparent window for deep tissue penetration. POM aggregated in an acidic tumor micro-environment (TME) whereby enables specific tumor targeting. In addition to the strong ability to produce singlet oxygen (1 O2 ) presumably via Russell mechanism, its excellent photothermal conversion enhances the CDT effect, offers additional tumor ablation modality, and permits NIR-II photoacoustic imaging. Benefitting from the reversible redox property of molybdenum, the theranostics based on POM can escape from the antioxidant defense system. Moreover, combining the specific responsiveness to TME and localized laser irradiation, side-effects shall be largely avoided.

The resource shortage and high cost of noble metal catalysts are still obstacles to their widespread applications. Herein, under the guidance of DFT calculation results, a facile and effective strategy for synthesizing noble metal-free catalysts is used to construct heteroatoms co-doped carbon catalyst. The N, P, S tri-doped hollow carbon nanospheres (NPSCSs) are synthesized via template-induced polymer-derived strategy and carbonization-etching-carbonization process. The obtained NPSCSs display special hollow structure with large specific surface area of 1154.89 m2 g−1. As expect, NPSCSs as bifunctional oxygen catalyst exhibit high-performance electrocatalytic activity. More attractively, as the cathode catalysts of assembled the Zn-air batteries (ZABs), NPSCSs show high maximum power density and long cycle stability. This strategy providing a new way to obtain multi-heteroatoms-doped electrocatalysts with excellent electrocatalytic activity and cycling stability.

Bipolar redox organics have attracted interest as electrode materials for energy storage owing to their flexibility, sustainability and environmental friendliness. However, an understanding of their application in all-organic batteries, let alone dual-ion batteries (DIBs), is in its infancy. Herein, we propose a strategy to screen a variety of phthalocyanine-based bipolar organics. The self-polymerizable bipolar Cu tetraaminephthalocyanine (CuTAPc) shows multifunctional applications in various energy storage systems, including lithium-based DIBs using CuTAPc as the cathode material, graphite-based DIBs using CuTAPc as the anode material and symmetric DIBs using CuTAPc as both the cathode and anode materials. Notably, in lithium-based DIBs, the use of CuTAPc as the cathode material results in a high discharge capacity of 236 mAh g-1 at 50 mA g-1 and a high reversible capacity of 74.3 mAh g-1 after 4000 cycles at 4 A g-1 . Most importantly, a high energy density of 239 Wh kg-1 and power density of 11.5 kW kg-1 can be obtained in all-organic symmetric DIBs.

Conjugated carbonyl compounds are deemed as high theoretical capacity and green electrode materials for lithium-ion batteries (LIBs) but are limited by their high dissolution and poor electronic conductivity. In this paper, we have successfully synthesized a series of multicarbonyl conjugated polymers using the coupling polymerization reaction and then constructed carbonyl-conjugated polymer/carbon nanotube hybrid films by a vacuum-filtration method. Importantly, the hybrid films could serve as a flexible, binder-free, and free-standing organic cathode for LIBs, which could deliver a high reversible discharge capacity of 142.3 mAh g-1 at 50 mA g-1, good cycling stability with a capacity retention of 74.6% at 500 mA g-1 after 300 cycles, and excellent rate capability of 120.6 mAh g-1 at 1000 mA g-1. In addition, the theoretical calculation has proved that the symmetrical conjugated structure can well accommodate four Li+ ions during the electrochemical reaction. Interestingly, the assembled full cell and flexible battery can power the small devices, suggesting its potential to use in bendable or wearable energy-storages devices.

The development of cost effective catalysts with high activity and 100% selectivity for hydrogen generation from the decomposition of hydrous hydrazine, a promising liquid-phase hydrogen carrier, is a critical challenge for the practical application of hydrous hydrazine to fuel cell vehicles. In this study, noble-metal-free NiCu/CeO2 bimetallic catalysts were readily synthesized using one-step solution combustion synthesis (SCS). The addition of Cu to Ni/CeO2 exhibited a synergistic effect to enhance the catalytic activity for the reaction. Catalyst characterization revealed that the improvement of catalytic performance is attributed to a combination of NiCu alloying, particle size of the active component, and formation of oxygen vacancy in the CeO2 lattice. The tailored 13 wt% Ni0.5Cu0.5/CeO2 catalyst exhibited 100% H2 selectivity in the temperature range 30–70 °C and 3.2-fold higher turnover frequency (TOF) of 1450.0 h−1 at 50 °C as compared to of the Ni/CeO2. This reactivity is also superior to that of most reported non-noble metal catalysts and is even comparable to noble metal-based catalysts.

Lithocarols A-F (1–6) possessing novel highly-oxygenated isobenzofuran core, together with a related known compound isoprenylisobenzofuran A (7) were isolated from the marine-derived fungus Phomopsis lithocarpus FS508. Among them, lithocarols A-E (1–5) represent the first examples of poly-ketal derivatives in tenellone family. The structures for all these compounds were fully elucidated by spectroscopic analysis, X-ray diffraction, and electronic circular dichroism calculations. Their cytotoxic assay disclosed that compounds 1–4 displayed moderate growth inhibitory effect against four human tumor cell lines with the IC50 values ranging from 10.5 to 38.7 μM.

Rechargeable Zn-air battery (ZAB) still relies on the precious metal-based catalysts, whose high cost, supply scarcity and inferior durability largely hamper the large-scale application of ZAB. Herein, a non-noble-metal catalyst towards both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is successfully constructed by carbonizing metal-organic frameworks (MOFs) functionalized electrospun nanofibers. The obtained bifunctional electrocatalyst shows good catalytic performance with comparable limiting diffusion current to Pt/C and comparable potential to RuO2, in particular, superior stability to both Pt/C and RuO2 towards ORR and OER. In view of the efficient bifunctional catalyst activity for ORR and OER, the obtained catalyst in ZAB displays high charge/discharge performance and long cycling stability, demonstrating great potential in grid-scale energy storage.

Developing novel low-cost and efficient electron transport layer (ETL) materials for high-efficiency planar heterojunction perovskite solar cells (PSCs) still remains challenges. Herein, we report a low-temperature colloid-synthesized and solution-deposited strontium stannate SrSnO3 (SSO) perovskite oxide nanoparticle can be an effective alternative ETL. More importantly, the introduction of yttrium dopant results in a significant improvement in the optoelectronic properties of yttrium-doped SrSnO3 (YSSO), exhibiting higher electron conductivity and faster electron transfer, as well as better band alignment at ETL/perovskite interface compare to undoped SSO, which is also supported by theory calculation. Consequently, these factors boost all photovoltaic performance parameters, leading to an improvement in the efficiency of planar PSCs. The resulting YSSO-based PSCs exhibit an average efficiency of 17.8% and a maximum power conversion efficiency of 19.0% with the significant reduction of J–V hysteresis, and those devices show high long-term stability as well. Our findings provide the full potential of the perovskite oxide toward future photovoltaic applications, especially for cost-efficient planar PSCs.

In this present work, we reported on a novel cyan-emitting phosphor Ba3Lu2B6O15:Ce3+,Tb3+ prepared by a conventional solid-state method and evaluated its potential as a candidate for application in white light-emitting diodes (WLEDs). X-ray diffraction (XRD), photoluminescence (PL) and photoluminescence excitation (PLE) spectra, CIE color coordinates, internal quantum efficiency (IQE), and temperature-dependent PL spectra were used to characterize the Ba3Lu2B6O15:Ce3+,Tb3+ phosphor. We found that this phosphor showed strong and broad absorption in 300–425 nm wavelength region, and under excitation at 373 nm it exhibited intense cyan emission due to the combination of blue emission of Ce3+ ions peaking at 446 nm and green emission of Tb3+ ions peaking at 542 nm. The energy transfer process from Ce3+ to Tb3+ ions in the Ba3Lu2B6O15:Ce3+,Tb3+ phosphor was studied. The optimized cyan-emitting Ba3Lu2B6O15:0.03Ce3+,0.2 Tb3+ sample showed CIE color coordinates of (0.204, 0.239) and its IQE was measured to be about 51%. The performance of this phosphor was further tested by investigating its thermal stability, and the obtained results demonstrated that this phosphor possessed good luminescence thermal stability and color thermal stability. Finally, we fabricated a WLED lamp by coating the Ba3Lu2B6O15:0.03Ce3+,0.2 Tb3+ cyan-emitting phosphor with a red-emitting CaAlSiN3:Eu2+ phosphor on a 365 nm-emitting LED chip, and when driven by a 180 mA forward bias current such WLED device produced intense white light with a color rendering index of 88, a correlated color temperature of 4213 K, and CIE color coordinates of (0.375, 0.388).

In this work, we study the BK¯ molecule in the Bethe-Salpeter (BS) equation approach. With the kernel containing one-particle-exchange diagrams and introducing two different form factors (monopole form factor and dipole form factor) in the vertex, we solve the BS equation numerically in the covariant instantaneous approximation. We investigate the isoscalar and isovector BK¯ systems, and we find that X5568 cannot be a BK¯ molecule.

In this work, green-emitting Ce3+-activated CaSr2Al2O6 (CSA) phosphors were successfully synthesized by solid-state reaction at high temperature and their phase purity, crystal structure, morphologies, photoluminescence properties, as well as the thermal stability were also investigated at length. The CSA:Ce3+ phosphors exhibited an intense broad green emission band in the 450–650 nm range centered at 545 nm under 375 nm near-ultraviolet light excitation. The full width at half maximum was about 94 nm. And the optimal doping concentration of Ce3+ ions in Ca1-xSr2Al2O6:xCe3+ was x = 0.01 (namely, 1 mol%). The CIE chromaticity coordinates of CSA:0.01Ce3+ samples were calculated to be (0.3553, 0.5541) with the corresponding internal quantum efficiency determined to be about 31%. Besides, the CSA:0.01Ce3+ phosphors possessed a high thermal stability. The green emission showed slight blue-shift at high-temperature, while its emission intensity at 423 K still maintained 71.3% of the initial value at 303 K. A prototype white light-emitting-diode (LED) lamp with a superb color rendering index (CRI = 92) and a low correlated color temperature (CCT = 3671 K) was successfully fabricated by combining a 365 nm near-ultraviolet-emitting LED chip with the CSA:0.01Ce3+ as a green component, BaMgAl10O17:Eu2+ as a blue component, and CaAlSiN3:Eu2+ as a red component.

Lithocarpinols A (1) and B (2), a pair of tenellone diastereoisomers with novel fused skeleton were isolated from the deep-sea derived fungus Phomopsis lithocarpus FS508. Their structures were elucidated by comprehensive spectroscopic analyses, X-ray diffraction and quantum molecular calculation. Their plausible biogenetic pathway featured an intriguing carbonyl-ene cyclization. Lithocarpinol A exhibited moderate inhibitory effect against HepG-2 and A549 tumor cell lines with IC50 values of 9.4 μmol/L and 10.9 μmol/L, respectively.

Accurate position detection of indoor objects is crucial for many intelligent life applications and can be realized by various approaches. In certain applications, indoor position detection can be performed using some forms of touch-based floor sensing systems to avoid problems faced by using vision or inertial navigation approaches. The present study develops a floor panel test stage (1 × 1 m2) and its associated localization schemes based on rigid body statics for evaluating the feasibility and the positioning performance on determining the indoor locations of moving objects such as mobile robots. The motion signals are detected by four load cells located at the panel corners and are used to determine the position of the applied forces by means of rigid body statics. Essential tests are performed to examine the system performance. Noticed that due to the existence of boundary reaction moments, traditional predictions based on rigid body statics may not be sufficient and a calibration procedure is required. In parallel, for accommodating different possible scenarios, the corresponding associated localization schemes for estimating the force-applied locations based on the readout history and algorithms are also proposed and realized. The results indicate that the localization accuracy is approximately ± 1 cm over a 1 m span after calibration. Although the method is essentially static, it can still detect object motion provided the motion frequency less than 2 Hz. Furthermore, demonstrations are also presented to highlight other possible applications such as center of gravity measurement of objects and the fusion of multiple localization schemes in indoor environment. Finally, an indoor localization demonstration based on both wiimote IR LED and this smart floor is presented to elucidate the possible application of this work in sensor fusion for indoor motion control.

We give a fully polynomial-time randomized approximation scheme (FPRAS) for the all-terminal network reliability problem, which is to determine the probability that, in a undirected graph, assuming each edge fails independently, the remaining graph is still connected. Our main contribution is to confirm a conjecture by Gorodezky and Pak (Random Struct. Algorithms, 2014), that the expected running time of the "cluster-popping" algorithm in bi-directed graphs is bounded by a polynomial in the size of the input., Comment: accepted to SICOMP

Red-emitting Ca3Y(AlO)3(BO3)4:Eu3+ (abbreviated as CYAB:Eu3+) phosphors with different Eu3+ doping concentrations were synthesized by a conventional solid-state method and their crystal structure, morphology, luminescence properties, decay curves and quantum efficiency were investigated in detail. The CYAB:Eu3+ phosphors can emit red light peaking at ∼ 621 nm under 397 nm excitation and the most intense red emission was obtained at the Eu3+ concentration of 50 mol%. From the concentration-dependent photoluminescence studies of CYAB:Eu3+ phosphors, the concentration quenching mechanism was dominated by dipole-dipole interaction. The as-prepared CYAB:0.5Eu3+ sample possessed good color coordinates of (0.653, 0.342) with high color purity of 90%. More importantly, the internal quantum efficiency of CYAB:0.5Eu3+ sample reached up to 88%. Furthermore, CYAB:Eu3+ exhibited good thermal stability and its emission intensity at 150 °C was still up to 76.3% of that at room-temperature. In addition, a prototype LED device was fabricated by coating a phosphor blend of BaMgAl10O7:Eu2+ blue phosphors, (Ba,Sr)2SiO4:Eu2+ green phosphors and CYAB:0.5Eu3+ red phosphors on the surface of 395 nm-emitting InGaN chip, which exhibited bright white light under 120 mA driven current. These good results indicate that the CYAB:Eu3+ phosphors are very appropriate red-emitting phosphors for applications in near-ultraviolet-excited white light-emitting diodes.

Organic carbonyl electrode materials are widely employed for alkali metal-ion secondary batteries in terms of their sustainability, structure designability and abundant resources. As a typical redox-active organic electrode materials, pyrene-4, 5, 9, 10-tetraone (PT) shows high theoretical capacity due to the rich carbonyl active sites. But its electrochemical behavior in secondary batteries still needs further exploration. Herein, PT-based linear polymers (PPTS) is synthesized with thioether bond as bridging group and then employed as an anode material for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). As expected, PPTS shows improved conductivity and insolubility in the non-aqueous electrolyte. When used as an anode material for LIBs, PPTS delivers a high reversible specific capacity of 697.1 mAh g-1 at 0.1 A g-1 and good rate performance (335.4 mAh g-1 at 1 A g-1 ). Moreover, a reversible specific capacity of 205.2 mAh g-1 at 0.05 A g-1 could be obtained as an anode material for SIBs.

Despite the large baryon-anti-baryon asymmetry in the observable Universe, the closely related phenomenon -- the violation of the combined charge and parity symmetry ($C\!P$V) -- has not been observed in the baryon sector in laboratories. In this paper, a new strategy for searching for $C\!P$V in heavy hadron multi-body decays is proposed, in which a set of novel observables measuring $C\!P$V in such decays -- the partial wave $C\!P$ asymmetries (PW$C\!P$As) -- are introduced. This strategy is model-independent and applicable to multi-body decays of heavy hadrons with arbitrary spin configurations in both initial and final states, and with any number of particles in the final state. It is especially applicable for $C\!P$V investigations in multi-body decays of heavy baryons. As applications of this strategy, we suggest to measure the PW$C\!P$As in some decay channels of bottom baryons such as $\Lambda_b^0\to p \pi^-\pi^+\pi^-$, $\Lambda_b\to p K^- \pi^+\pi^-$, $\Lambda^0_b\to p\pi^-K^+K^-$, $\Lambda_b^0\to\Lambda K^+\pi^-$, and $\Lambda_b^0\to p \pi^- K_s$.}, Comment: 15 pages, 4 figures, 2 tables, accepted for publication in JHEP

We interpret the $X_1(2900)$ as an $S$-wave $\bar{D}_1K$ molecular state in the Bethe-Salpeter equation approach with the ladder and instantaneous approximations for the kernel. By solving the Bethe-Salpeter equation numerically with the kernel containing one-particle-exchange diagrams and introducing three different form factors (monopole, dipole, and exponential form factors) in the verties, we find the bound state exists. We also study the decay width of the decay $X_1(2900)$ to $D^-K^+$., Comment: 13 pages, 4 figures. arXiv admin note: text overlap with arXiv:2004.14085, arXiv:1906.09002