Electrolyte additive is an effective strategy to inhibit the uncontrolled growth of Li dendrites for lithium metal batteries (LMBs). However, most of the additives are complex synthesis and prone to ...decompose in cycling. Herein, in order to guide the homogeneous deposition of Li+, carbonized polymer dots (CPDs) as electrolyte additives are successfully designed and synthesized by microwave (M‐CPDs) and hydrothermal (H‐CPDs) approaches. The controllable functional groups containing N or O (especially pyridinic‐N, pyrrolic‐N, and carboxyl group) enable CPDs to keep stable in electrolytes for at least 3 months. Meanwhile, the clusters formed between CPDs and Li+ through electrostatic interaction effectively guide the uniform Li dispersion and limit the “tip effect” and dendrite formation. Moreover, as lithiophilic groups increase, the strong electrostatic interference for the solvation effect of Li+ in the electrolyte is formed, which induces faster Li+ diffusion/transfer. As expected, H‐CPDs achieve the ultra‐even Li+ transfer. The corresponding Li//LiFePO4 full cell delivers a high capacity retention rate of 93.8% after 200 cycles, which is much higher than that of the cells without additives (61.2%) and with M‐CPDs (83.7%) as additives. The strategy in this work provides a theoretical direction for CPDs as electrolyte additives used in energy storage devices.
Two kinds of carbonized polymer dots (CPDs) (M‐CPDs and H‐CPDs) as electrolyte additives are successfully designed and synthesized. H‐CPDs with more pyridinic‐N, pyrrolic‐N, and COOH deliver more even Li+ flux through abundant H‐CPDs‐Li clusters bound by strong electrostatic interaction. The symmetrical cell exhibits enhanced cycling stability of 3700 h.
Three carbazole-based multiple resonance dendrimers namely D1-BNN, D2-BNN and D3-BNN, are developed for solution-processed narrowband blue organic light-emitting diodes (OLEDs) by introducing the ...first-, second-, and third-generation carbazole dendrons in periphery of boron, nitrogen-doped polycyclic aromatic hydrocarbon skeleton. Different from D1-BNN containing first-generation carbazole dendron showing moderate photoluminescent quantum efficiency (PLQY) of 68% in solid state and broadened emission bands with full-width at half maximum (FWHM) increasing from 26 nm to 34 nm upon doping concentration growing from 10 wt% to 40 wt%, D3-BNN with the third-generation carbazole dendron exhibits high PLQY of 92% and weak dependence of photoluminescent spectra on doping concentration, which can remain narrowband emissions with unchanged FWHM of 24 nm at same doping concentration range. Solution-processed OLEDs employing D3-BNN as emitter reveal blue electroluminescence at 477 nm with FWHM of 24 nm, and maximum external quantum efficiency (EQE) of 17.3% which is kept at 14.4% at doping concentration of 40 wt%, much superior than the D1-BNN devices showing maximum EQE of 13.0% that drops to 3.7% at 40 wt% doping concentration.
With the development of wearable electronic devices towards flexibility, safety, and functionality, supercapacitors are required to simultaneously possess satisfactory energy density and flexibility. ...Although the environmental friendliness, high theoretical capacity and tunable structure of CuS, the instability of their corresponding compounds on the flexible substrate as well as its poor conductivity limit its development. To address these issues, a pea-like hollow CuS nanoparticle structure is fabricated on the surface of carbon fiber with Cu plating, and a novel kind of flexible electrode named CPCC@CuO@CuS-H is synthesized. The inner copper plating of the electrode brings good electronic conductivity, and the hollow structure effectively improves the charge diffusion ability. CPCC@CuO@CuS-H has ultra-high mass specific capacity of 1387.1 F g−1 in an electrolyte of 2.0 M KOH solution under 2 A g−1. Moreover, the construction of disulfide bond in electrode can effectively improve the stability of hollow structure. The electrode has satisfactory rate performance and long cycle life at an ultra-high current density of 20 A g−1. Especially, by assembling a flexible all-solid-state supercapacitor (CPCC@CuO@CuS-H//CC@AC), the operating voltage closes to 1.8 V, and the energy density achieves the aim of 139.5 Wh kg−1 when the high-power density is located at 1800 W kg−1, with 82.9% electric capacity retaining after 10000 cycles, showing its promising potential in flexible devices.
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•Hollow porous materials with good stability can be prepared by simple S-S bonds.•The electrode has high capacity (1387.1 F g−1 at 2 A g−1) and decent flexibility.•The electrode achieves a high electron conductivity with Rct values 0.30 Ω.•The FASC has a high energy density (139.5 W h kg−1 at 1800 W kg−1).•The FASC exhibits outstanding cycle performance (higher than 10,000 cycles).
A novel kind of porous boron-doped carbon (TNPBC) with a termite nest structure was synthesized by combining doping, activation, and pyrolysis into one step. Using the synthesized material as a ...sulfur reservoir, TNPBC effectively relieved the “shuttle effect” commonly found in Li-S electrodes and achieved a decent rate performance in Li-S and sodium ion batteries.
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Lithium sulfur (Li-S) batteries possess high theoretical specific capacity (1675mAhg−1) and energy density (2567Whkg−1), but are plagued by their poor rate performance. The discovery of new carbon sources, design of novel porous carbon structures, and effective hetero-atom doping of the sulfur matrix are key to overcome this dilemma. In this paper, a boron-doped porous carbon material with a termite nest shape (TNPBC) was obtained from a new carbon source, polyaspartic acid, and borax. Importantly, the doping, activation, and pyrolysis were integrated into one step through a low cost and simple methodology. The borax was essential to formation of a high surface porous architecture and provided boron dopants, which, combined with polyaspartic acid, achieves co-doping (B and N) carbon materials with special porous structures. The simultaneous pore-formation and doping leave an abundance of hetero-atoms exposed on the surface of pores, which enhances the electrostatic interactions between the hetero-atoms and the charged species in the batteries. As a result, the S/TNPBC cathode maintains a stable capacity of 703mAhg−1 with an excellent Coulombic efficiency of 101.3% after 120 cycles at 0.1C. Moreover, it exhibits an excellent rate capability with an initial capacity of 650mAhg−1 at 0.5C and sustains a capacity of 500mAhg−1 after 100 cycles. Furthermore, when TNPBC is used as the anode in a sodium ion battery, an excellent rate capability is achieved. The specific charge capacity is three times greater than without boron doping at 500mAg−1. Due to the simple fabrication process and desirable properties of this novel architecture, TNPBC provides a new strategy for enhancing the performance of commercial energy storage devices.
Bread wheat (Triticum aestivum, AABBDD) is one of the most widely cultivated and consumed food crops in the world. However, the complex polyploid nature of its genome makes genetic and functional ...analyses extremely challenging. The A genome, as a basic genome of bread wheat and other polyploid wheats, for example, T. turgidum (AABB), T. timopheevii (AAGG) and T. zhukovskyi (AAGGA(m)A(m)), is central to wheat evolution, domestication and genetic improvement. The progenitor species of the A genome is the diploid wild einkorn wheat T. urartu, which resembles cultivated wheat more extensively than do Aegilops speltoides (the ancestor of the B genome) and Ae. tauschii (the donor of the D genome), especially in the morphology and development of spike and seed. Here we present the generation, assembly and analysis of a whole-genome shotgun draft sequence of the T. urartu genome. We identified protein-coding gene models, performed genome structure analyses and assessed its utility for analysing agronomically important genes and for developing molecular markers. Our T. urartu genome assembly provides a diploid reference for analysis of polyploid wheat genomes and is a valuable resource for the genetic improvement of wheat.
Identifying conservation units is crucial for the effective conservation of threatened species. Previous cases are almost exclusively based on large‐scale but coarse sampling for genetic structure ...analyses. Significant genetic structure can occur within a small range, and thus multiple conservation units may exist in narrowly distributed plants. However, small‐scale genetic structure is often overlooked in conservation planning especially for wind‐pollinated and wind‐dispersed trees, largely due to the absence of dense and elaborate sampling. In this study, we focused on a representative endangered relict plant, Metasequoia glyptostroboides. Using both nuclear microsatellites (nSSRs) and chloroplast DNA (cpDNA) fragments, we sampled across the narrow distribution range of this species and determined its conservation units by exploring its genetic structure and historical demography. cpDNA haplotypes were classified into two groups, but mixed in space, suggesting that the existent wild trees of M. glyptostroboides cannot be divided into different evolutionarily significant units. However, using nSSRs, we detected strong spatial genetic structure, with significant genetic differentiation and weak gene flow between the samples in the east of the species' distribution range and other samples. The divergence between the two nSSR groups was dated to the Last Glacial Maximum (c. 19.6 kya), suggesting that such spatial genetic structure has been maintained for a long term. Therefore, these two nSSR groups should be considered as different conservation units, that is, management units, to protect intergroup genetic variations, which is likely to be the outputs of local adaptation. Our findings highlight the necessity to reveal small‐scale genetic structure and population demography to improve the conservation strategies of evolutionary potential of endangered plants.
nSSRs‐based genetic structure and population demography analysis show two spatially segregated genetic groups with limited intergroup gene flow. Therefore, two management units should be set up to protect intergroup genetic variations.
In this study, polyphenols from sweet potato leaves were purified by macroporous resin, and antioxidant activity was evaluated by free radical scavenging. AB-8, D-101, HPD-100 and DM301 four resins ...were selected for purification. The antioxidant activity was evaluated by 2,4-dinitrophenylhydrazine (DPPH) and 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonate) (ABTS) methods. The results showed that the DM-301 macroporous adsorption resin was most suitable by static adsorption–desorption method, and the optimal purification conditions were determined by single factor experiment as follows: the concentration of sample solution 6.0 mg/mL, the flow rate of sample solution 60 mL/min, the volume fraction of ethanol desorption 60%, and the flow rate 40 mL/h. The scavenging rates of DPPH and ABTS free radicals by purified polyphenols from sweet potato leaves were 74.04% and 98.20%, respectively. The research results provide reference for further development and utilization of polyphenols from sweet potato leaves.
Background: Patients with acute coronary syndrome (ACS) still have a high risk of recurrence of major adverse cardiovascular and cerebrovascular events (MACCE). However, there are rare studies on the ...prediction of MACCE in patients with ACS using lipoprotein a Lp(a) combined with fibrinogen. The aim of this study was to analyze the predictive value of Lp(a) combined with fibrinogen for the long-term prognosis of patients with ACS. Methods: 804 patients with ACS admitted to 11 tertiary general hospitals in Chengdu from January 2017 to June 2019 were included in the study. According to the Lp(a) 300 mg/L, patients were assigned to the non-high Lp(a) group and high Lp(a) group. Patients were assigned to the non-high or high fibrinogen groups using the fibrinogen level of 3.08 g/L. Subsequently, patients were divided into group A, B, or C by Lp(a) combined with fibrinogen. The study endpoints were MACCE, including all-cause death, non-fatal myocardial infarction, non-fatal stroke, and revascularization. The incidences of MACCE among groups were compared. Lp(a), fibrinogen, Lp(a) combined with fibrinogen classifications were each added into the basic model to construct three new models. The C-index, net reclassification index (NRI) and integrated discrimination improvement (IDI) of the three new models were then compared. Results: The median follow-up was 16 months. During follow-up, the cumulative incidence of MACCE in group C was significantly higher than that measured in group A and B (p < 0.001). The results of the multivariate Cox regression analysis of MACCE showed that Lp(a) ≥300 mg/L with fibrinogen ≥3.08 g/L was an independent predictor of MACCE. According to the GRACE score and the statistical analyses, the basic model was constructed, which had a C-index of 0.694. The C-index, NRI, and IDI of the new model constructed using the basic model + Lp(a) combined with fibrinogen classification were 0.736, 0.095, and 0.094 respectively. Conclusions: Single Lp(a), single fibrinogen and Lp(a) combined with fibrinogen were independent predictors of MACCE in patients with ACS. The predictive value of Lp(a) combined with fibrinogen in patients with ACS was better than that of single Lp(a) and single fibrinogen.
Energy storage technology is critical for intelligent power grids. It has great significance for the large-scale integration of new energy sources into the power grid and the transition of the energy ...structure. Based on the existing technology of isothermal compressed air energy storage, this paper presents a design scheme of isothermal compressed air energy storage power station, which uses liquid to compress air, hydraulic piston to transfer potential energy, hydraulic turbine to generate electricity at constant pressure, and liquid occupancy to store the gas at constant pressure. Then the technical features and control strategies of its internal temperature control subsystem are studied, and the mathematical model is constructed. A hierarchical relay operation is put forward to address the actual construction and operational requirements of compressed air energy storage power plants. Finally, through physical platform experiments and MATLAB simulation, the feasibility of the design is validated.
Density functional theory (DFT) and time-dependent DFT (TD-DFT) were used to calculate the properties of the carbazole dyes
TYZ-1
to
TYZ-5
, which differed in their π-spacers. The carbazole dyes
...TYZ-6
and
TYZ-7
were then designed; these were based on
TYZ-3
(which had 2,2′:5′,2″-terthiophene as its π-spacer) but had more strongly electron-withdrawing second acceptor groups than
TYZ-3
. All of these dyes except for
TYZ-5
presented quasi-planar conformations, and the calculated energies of their highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) molecular orbitals as well as their HOMO-LUMO gaps (
E
g
) suggest that these dyes are suitable for use as sensitizers. Lengthening the π-spacer and increasing its degree of conjugation were found to cause the absorption spectrum of the dye to redshift and to facilitate hole injection. The
E
g
values of
TYZ-6
and
TYZ-7
were calculated to be smaller than that of
TYZ-3
due to the weaker electron-withdrawing power of the second acceptor group in
TYZ-3
, and the dyes
TYZ-2
,
TYZ-3
,
TYZ-6
, and
TYZ-7
presented the smallest
E
g
values. Local electron excitations following UV-vis absorption led to electronic transitions, particularly HOMO to LUMO transitions (> 94.3% of all transitions). The excited states of these dyes were found to have quasi-planar conformations, although their dihedral angles were smaller than those in the corresponding ground states. The Stokes Shifts calculated for the seven dyes (which ranged from 51.9 to 98.1 nm) suggested that self-absorption was unlikely to occur. Overall, the calculations indicated that the dyes
TYZ-2
,
TYZ-3
,
TYZ-6
, and
TYZ-7
are promising candidates for use in dye-sensitized solar cells.
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