Lateral epitaxial growth of two-dimensional organic heterostructures.

Two-dimensional organic lateral heterostructures (2D OLHs) are attractive for the fabrication of functional materials. However, it is difficult to control the nucleation, growth and orientation of two distinct components. Here we report the combination of two methods-liquid-phase growth and vapour-phase growth-to synthesize 2D OLHs from perylene and a perylenecarboxaldehyde derivative, with a lateral size of ~20 µm and a tunable thickness ranging from 20 to 400 nm. The screw dislocation growth behaviour of the 2D crystals shows the spiral arrangement of atoms within the crystal lattice, which avoids volume expansion and contraction of OLH, thereby minimizing lateral connection defects. Selective control of the nucleation and sequential growth of 2D crystals leads to structural inversion of the 2D OLHs by the vapour-phase growth method. The resulting OLHs show good light-transport capabilities and tunable spatial exciton conversion, useful for photonic applications. This synthetic strategy can be extended to other families of organic polycyclic aromatic hydrocarbons, as demonstrated with other pyrene and perylene derivatives.

Thickness-variation-insensitive near-infrared quantum dot LEDs.

In terms of tunable luminescence and high quantum efficiency, colloidal quantum dots (CQDs) are promising semiconductors for constructing near-infrared light-emitting diodes (NIR-LEDs). However, currently available NIR-LEDs are susceptible to variations in the emission layer thickness (EMLT), the highest external quantum efficiency (EQE) decreases to below 50% (relative to peak EQE) when the EMLT varies out of a narrow range of (±30 nm). This is due to the thickness-dependent carrier recombination rate and current density variation, resulting in batch-to-batch EQE fluctuations that limit LED reproducibility. Here we report efficient NIR-LEDs that exhibit EQE variations of less than 15% (relative to the champion EQE) over an EMLT range of 40-220 nm; the highest achievable EQE of ∼11.5% was obtained by encapsulating a 212 nm-thick CQD within a type-I inorganic shell to enhance the radiative recombination in the dots, resulting in a high photoluminescence quantum yield of 80%, and by post-treating the films with a bifunctional linking agent to improve and balance the hole and electron mobilities in the entire film (electron mobility: 8.23 × 10-3 cm2 V-1 s-1; hole mobility: 7.0 × 10-3 cm2 V-1 s-1). This work presents the first NIR-LEDs that exhibit EMLT-invariant EQE over an EMLT range of 40-220 nm, which represents the highest EQE among reported CQD NIR-LEDs with a QD thickness exceeding 100 nm.

Advances in Solution-Processed Blue Quantum Dot Light-Emitting Diodes.

Quantum dot light-emitting diodes (QLEDs) have been identified as a next-generation display technology owing to their low-cost manufacturing, wide color gamut, and electrically driven self-emission properties. However, the efficiency and stability of blue QLEDs still pose a significant challenge, limiting their production and potential application. This review aims to analyse the factors leading to the failure of blue QLEDs and presents a roadmap to accelerate their development based on the progress made in the synthesis of II-VI (CdSe, ZnSe) quantum dots (QDs), III-V (InP) QDs, carbon dots, and perovskite QDs. The proposed analysis will include discussions on material synthesis, core-shell structures, ligand interactions, and device fabrication, providing a comprehensive overview of these materials and their development.

Efficient Near-Infrared Electroluminescence from Lanthanide-Doped Perovskite Quantum Cutters.

Perovskite nanocrystals (PeNCs) deliver size- and composition-tunable luminescence of high efficiency and color purity in the visible range. However, attaining efficient electroluminescence (EL) in the near-infrared (NIR) region from PeNCs is challenging, limiting their potential applications. Here we demonstrate a highly efficient NIR light-emitting diode (LED) by doping ytterbium ions into a PeNCs host (Yb3+ : PeNCs), extending the EL wavelengths toward 1000 nm, which is achieved through a direct sensitization of Yb3+ ions by the PeNC host. Efficient quantum-cutting processes enable high photoluminescence quantum yields (PLQYs) of up to 126 % from the Yb3+ : PeNCs. Through halide-composition engineering and surface passivation to improve both PLQY and charge-transport balance, we demonstrate an efficient NIR LED with a peak external quantum efficiency of 7.7 % at a central wavelength of 990 nm, representing the most efficient perovskite-based LEDs with emission wavelengths beyond 850 nm.

Distribution of Diatoms in the Navigable Sections of Beijing-Hangzhou Grand Canal.

OBJECTIVES: To establish a diatom database by analyzing the quatity, species distribution and differences of diatom in water samples of the whole navigable sections of the Beijing-Hangzhou Grand Canal, to provide a reference for the inference of the drowning site. METHODS: Water samples were collected at 22 sites in the navigable sections of the Beijing-Hangzhou Grand Canal (Jining section to Yangzhou Section), and the diatoms at each site were qualitatively and quantitatively analyzed by using graphite digestion-scanning electron microscopy. RESULTS: Sampling site T (Laohuaijiang River Line, Gaoyou City, Yangzhou City, Jiangsu Province) had the highest number of diatoms, while sampling site O (Siyang County, Suqian City, Jiangsu Province) had the lowest number of diatoms, with a large gap of 68 times. At sampling site Q (Jiangpu District, Huaian city, Jiangsu Province), there were 19 species of diatoms. The sampling site O had the least diatoms, with 7 species. There were no significant differences in species evenness and species diversity at each sampling site (P>0.05). Some sampling sites have characterized diatoms, such as Caloneis at station A (Taibai Lake, Weishan County, Shandong Province), Rhoicosphenia at station B (Nanyang Town, Weishan County, Shandong Province), Amphora at station I (Taierzhuang District, Zaozhuang City, Shandong Province) and Epithemia at station J (Pizhou 310 national highway, Xuzhou City, Jiangsu Province). CONCLUSIONS: The species richness of diatoms gradually increased from north to south. Diatom species richness and species diversity might be higher in areas with complex environments and large population flow. Climate type has a certain influence on the distribution of diatoms.

Full-Dimensional Grain Boundary Stress Release for Flexible Perovskite Indoor Photovoltaics.

Perovskite photovoltaics are strong potential candidates to drive low-power off-grid electronics for indoor applications. Compared with rigid devices, flexible perovskite devices can provide a more suitable surface for indoor small electronic devices, enabling them have a broader indoor application prospect. However, the mechanical stability of flexible perovskite photovoltaics is an urgent issue solved. Herein, a kind of 3D crosslinking agent named borax is selected to carry out grain boundary penetration treatment on perovskite film to realize full-dimensional stress release. This strategy improves the mechanical and phase stabilities of perovskite films subjected to external forces or large temperature changes. The fabricated perovskite photovoltaics deliver a champion power conversion efficiency (PCE) of 21.63% under AM 1.5G illumination, which is the highest one to date. The merit of low trap states under weak light makes the devices present a superior indoor PCE of 31.85% under 1062 lux (LED, 2956 K), which is currently the best flexible perovskite indoor photovoltaic device. This work provides a full-dimensional grain boundary stress release strategy for highly stable flexible perovskite indoor photovoltaics.

Discovery of 3-(4-hydroxybenzyl)-1-(thiophen-2-yl)chromeno[2,3-c]pyrrol-9(2H)-one as a phosphodiesterase-5 inhibitor and its complex crystal structure.

Phosphodiesterase-5 (PDE5) inhibitors have been approved for the treatment of erectile dysfunction and pulmonary hypertension, but enthusiasm on discovery of PDE5 inhibitors continues for their potential new applications. Reported here is discovery of a series of new PDE5 inhibitors by structure-based design, molecular docking, chemical synthesis, and enzymatic characterization. The best compound, 3-(4-hydroxybenzyl)-1-(thiophen-2-yl)chromeno[2,3-c]pyrrol-9(2H)-one (57), has an IC50 of 17 nM against the PDE5 catalytic domain and good selectivity over other PDE families. The crystal structure of the PDE5 catalytic domain in complex with 57 was determined at 2Å resolution and showed that 57 occupies the same pocket as other PDE5 inhibitors, but has a different binding pattern in detail. On the basis of the binding pattern of 57, a novel scaffold can be proposed as a candidate of PDE inhibitors.

Self-assembled oligomeric procyanidin-insulin hybrid nanoparticles: a novel strategy for controllable insulin delivery.

Natural oligomeric procyanidin (OPC) with high biological and pharmacological activities was successfully used to synthesize OPC-insulin (OPC-INS) nanoparticles with different aggregation sizes for sustained and controlled delivery of hydrophilic insulin. The aggregation size of OPC-INS nanoparticles was regulated by OPC concentration, pH value, and incubation time. The fabrication mechanism would be that OPC and insulin self-assembled into a mixture of insulin aggregates via intermolecular interactions. In the self-assembly of insulin, OPC could serve both in the encompassing of insulin aggregates as a stabilizer and cross-linking different amounts of insulin aggregates into OPC-INS nanoparticles as interphase. OPC-INS nanoparticles not only demonstrated effective insulin drug loading but also exhibited aggregation-size-dependent and controlled insulin release performance in vitro. In the best case for OPC-INS nanoparticles, only ∼21% of insulin was released in 37 days. This study showed that the OPC-INS nanosystem is promising to serve as a long-acting insulin release formulation, and OPC has great potential as a drug carrier for nanomedicine.

Synthesis and evaluation of curcumin analogues as potential thioredoxin reductase inhibitors.

Series of curcumin derivatives were synthesized; the inhibitory activities on thioredoxin reductase (TrxR) of all analogues were evaluated by DTNB assay in vitro. It is found that most of the analogues can inhibit TrxR in the low micromolar range; Structure-activity relationship analysis reveals that analogues with furan moiety have excellent inhibitory effect on TrxR in an irreversible manner, indicating that the furan moiety may serve as a possible pharmacophore during the interaction of curcumin analogues with TrxR. The effect of selected curcuminoids on growth of different TrxR overexpressed cancer cell lines was also investigated and discussed.

[The discovery of a novel flower color mutation in male sterile rapeseed ( Brassica napus L. )].

The author found a novel yellow-white flower color mutation in the male sterile progenies derived from a commercial Brassica.napus hybrid C022, which was produced by a male sterility line 9012A, whose sterility was controlled by interaction between two pairs recessive genes and a pair of epitatic genes. The mutant was named 991S. 991S had three morphologic characters:(1) The color in the middle of every petal was yellow, yet the both sides were white.(2)Every calyx might become striped albino (3) Only male sterile plants in different populations had mutative character. Except flower color, they had similar morphologic characters to the normal male sterile sib-plants. The plants were slender and little with little flowers that had flat petals, bended stigmas, degenerative stamen, and dry anthers. Primary analysis of its origin and inheritance showed that this mutative character was controlled by recessive partial albino gene.