Organic-inorganic lead halide quasi-two-dimensional (2D) perovskites are promising gain media for lasing applications because of their low cost, tunable colour, excellent stability and solution ...processability
. Optically pumped continuous-wave (CW) lasing is highly desired for practical applications in high-density integrated optoelectronics devices and constitutes a key step towards electrically pumped lasers
. However, CW lasing has not yet been realized at room temperature because of the 'lasing death' phenomenon (the abrupt termination of lasing under CW optical pumping), the cause of which remains unknown. Here we study lead halide-based quasi-2D perovskite films with different organic cations and observe that long-lived triplet excitons considerably impede population inversion during amplified spontaneous emission and optically pumped pulsed and CW lasing. Our results indicate that singlet-triplet exciton annihilation is a possible intrinsic mechanism causing lasing death. By using a distributed-feedback cavity with a high quality factor and applying triplet management strategies, we achieve stable green quasi-2D perovskite lasers under CW optical pumping in air at room temperature. We expect that our findings will pave the way to the realization of future current-injection perovskite lasers.
Theoretical calculations reveal that intrinsic pentagons in the basal plane can contribute to the local electronic redistribution and the contraction of band gap, making the carbon matrix possess ...superior binding affinity and electrochemical reactivity. To experimentally verify this, a pentagon‐defect‐rich carbon nanomaterial was constructed by means of in situ etching of fullerene molecules (C60). The electrochemical tests show that, relative to hexagons, such a carbon‐based material with abundant intrinsic pentagon defects makes much greater contribution to the electrocatalytic oxygen reduction activity and electric double layer capacitance. It shows a four‐electron‐reaction mechanism similar to commercial Pt/C and other transition‐metal‐based catalysts, and a higher specific capacitance than many reported metal‐free carbon materials. These results show the influence of intrinsic pentagon defects for developing carbon‐based nanomaterials toward energy conversion and storage devices.
The intrinsic pentagon defects of carbon‐based materials make a greater contribution to the electrocatalytic oxygen reduction activity and electric double‐layer capacitance relative to common hexagons. When pentagon defects are combined with nitrogen dopants, the as‐obtained material shows promise in practical Zn‐‐air batteries (picture: left) and supercapacitors (right).
•1T-MoS2/PANI was fabricated via electrostatic attraction-induced self-assembly.•The hybrids possess unique alternating microstructure.•The interfaces between 1T-MoS2 and PANI greatly enhance its ...performance.•The capacitance retention is up to 91% at 10A/g after 2000 cycles.
In this work, metallic 1T-MoS2/polyaniline (PANI) heterostructures with unique alternating arrangement are fabricated via an electrostatic attraction-induced self-assembly approach. Negatively charged metallic 1T-MoS2 monolayers are first obtained by chemical exfoliation, followed by the mixing with PANI and acidification. The neutralization of surface charges triggers spontaneous self-assembly, leading to the formation of alternating stacked 1T-MoS2/PANI heterostructures. Such unique architecture maximizes the interfacial contact between metallic 1T-MoS2 and PANI and enhances synergistic effect between them. The close atomic contact not only greatly improves the electron and ion transport of the nanocomposites, but also gives rise to good structural stability due to the strong interactions between the intimately contacted 1T-MoS2 and PANI. Furthermore, the compatibility of the nanocomposites with the aqueous electrolyte is also greatly improved. As a result, high specific capacitance and excellent cycling stability are achieved when the heterostructures are studied as electrode materials in supercapacitors. The capacitance retention is up to 91% at 10A/g after 2000 cycles.
In this article, a simple self-assembly strategy for fabricating van der Waals heterostructures from isolated two-dimensional atomic crystals is presented. Specifically, dopamine (DOPA), an excellent ...self-assembly agent and carbon precursor, was adsorbed on exfoliated MoS2 monolayers through electrostatic interaction, and the surface-modified monolayers self-assembled spontaneously into DOPA-intercalated MoS2. The subsequent in situ conversion of DOPA to highly conductive nitrogen-doped graphene (NDG) in the interlayer space of MoS2 led to the formation of a novel NDG/MoS2 nanocomposite with well-defined alternating structure. The NDG/MoS2 was then studied as an anode for lithium-ion batteries (LIBs). The results show that alternating arrangement of NDG and MoS2 triggers synergistic effect between the two components. The kinetics and cycle life of the anode are greatly improved due to the enhanced electron and Li+ transport as well as the effective immobilization of soluble polysulfide by NDG. A reversible capacity of more than 460 mAh/g could be delivered even at 5 A/g. Moreover, the abundant voids created at the MoS2–NDG interface also accommodate the volume change during cycling and provide additional active sites for Li+ storage. These endow the NDG/MoS2 heterostructure with low charge-transfer resistance, high sulfur reservation, and structural robustness, rendering it an advanced anode material for LIBs.
Osteoporosis is a systemic metabolic bone disorder characterized by a decrease in bone mass and degradation of the bone microstructure, leaving bones that are fragile and prone to fracture. Most ...osteoporosis treatments improve symptoms, but to date there is no quick and effective therapy. Bone marrow mesenchymal stem cells (BMMSCs) have pluripotent potential. In adults, BMMSCs differentiate mainly into osteoblasts and adipocytes in the skeleton. However, if this differentiation is unbalanced, it may lead to a decrease in bone mass. If the number of adipocyte cells increases and that of osteoblast cells decreases, osteoporosis can result. A variety of hormones and cytokines play an important role in the regulation of BMMSCs bidirectional differentiation. Therefore, a greater understanding of the regulation mechanism of BMMSC differentiation may provide new methods to prevent and treat osteoporosis. In addition, autologous, allogeneic BMMSCs or genetically modified BMMSC transplantation can effectively increase bone mass and density, increase bone mechanical strength, correct the imbalance in bone metabolism, and increase bone formation, and is expected to provide a new strategy and method for the treatment of osteoporosis.
Abstract
Vision-based precision measurement is limited by the optical resolution. Although various super-resolution algorithms have been developed, measurement precision and accuracy are difficult to ...guarantee. To achieve nanoscale resolution measurement, a super-resolution microstructure concept is proposed which is based on the idea of a strong mathematical mapping relationship that may exist between microstructure surface topography features and the corresponding image pixel intensities. In this work, a series of microgrooves are ultra-precision machined and their surface topographies and images are measured. A mapping relationship model is established to analyze the effect of the microgroove surface topography on the imaging mechanism. The results show that the surface roughness and surface defects of the microgroove have significant effects on predicting the imaging mechanism. The optimized machining parameters are determined afterward. This paper demonstrates a feasible and valuable work to support the design and manufacture super-resolution microstructure which has essential applications in precision positioning measurement.
Emission thermal quenching is commonly observed in quasi-2D perovskite emitters, which causes the severe drop in luminescence efficiency for the quasi-2D perovskite light-emitting diodes (PeLEDs) ...during practical operations. However, this issue is often neglected and rarely studied, and the root cause of the thermal quenching has not been completely revealed now. Here, we develop a passivation strategy via the 2,7-dibromo-9,9-bis (3'-diethoxylphosphorylpropyl)-fluorene to investigate and suppress the thermal quenching. The agent can effectively passivate coordination-unsaturated Pb
defects of both surface and bulk of the film without affecting the perovskite crystallization, which helps to more truly demonstrate the important role of defects in thermal quenching. And our results reveal the root cause that the quenching will be strengthened by the defect-promoted exciton-phonon coupling. Ultimately, the PeLEDs with defect passivation achieve an improved external quantum efficiency (EQE) over 22% and doubled operation lifetime at room temperature, and can maintain about 85% of the initial EQE at 85 °C, much higher than 17% of the control device. These findings provide an important basis for fabricating practical PeLEDs for lighting and displays.
To explore and compare urine proteome changes among rat models by intraperitoneal injection with single bacteria and co-injection with two bacteria.
Escherichia coli and Staphylococcus aureus are two ...common human pathogens. Three rat models were established: (i) the intraperitoneal co-injection of E. coli and S. aureus model (ES model), (ii) intraperitoneal injection of E. coli model (E model), and (iii) intraperitoneal injection of S. aureus model (S model). Urinary proteomes on days 0, 1 and 2 of the three models were analyzed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS).
A total of 111, 34 and 94 differential proteins were identified in the ES model, E model and S model, respectively. Among them, some differential proteins were reported to be associated with bacterial infection. Approximately 47% differential proteins in the E model overlapped with ES model, and 37% differential proteins in the S model overlapped with ES model. Compared with the E model and S model, a total of 71 unique differential proteins were identified in the ES model.
Our results indicated that (1) the urine proteome could distinguish different bacterial intraperitoneal injections models and (2) the effects of co-injection with two bacteria on the urine proteome were not simple superposition of single injection.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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