Long-lived isospin excitations in magic-angle twisted bilayer graphene.

Numerous correlated many-body phases, both conventional and exotic, have been reported in magic-angle twisted bilayer graphene (MATBG)1-24. However, the dynamics associated with these correlated states, crucial for understanding the underlying physics, remain unexplored. Here we combine exciton sensing and optical pump-probe spectroscopy to investigate the dynamics of isospin orders in MATBG with WSe2 substrate across the entire flat band, achieving sub-picosecond resolution. We observe remarkably slow isospin dynamics in a broad filling range around ν = 2 and between ν = -3 and -2, with lifetimes of up to 300 ps that decouple from the much faster cooling of electronic temperature (about 10 ps). This non-thermal behaviour demonstrates the presence of abnormally long-lived modes in the isospin degrees of freedom. This observation, not anticipated by theory, implies the existence of long-range propagating collective modes, strong isospin fluctuations and memory effects and is probably associated with an intervalley coherent or incommensurate Kekulé spiral ground state. We further demonstrate non-equilibrium control of the isospin orders previously found around integer fillings. Specifically, through ultrafast manipulation, it can be transiently shifted away from integer fillings. Our study demonstrates a unique probe of collective excitations in MATBG and paves the way for actively controlling non-equilibrium phenomena in moiré systems.

Doublet-emissive materials for organic light-emitting diodes: exciton formation and emission processes.

Doublet-emission is mainly discovered in stable radicals, lanthanide-metal complexes with an f1 electron configuration and transition-metal complexes with a low-spin d5 electron configuration, and has a distinct radiation mechanism from closed-shell luminescent molecules and thus technology opportunities. There exists an unpaired electron in the frontier molecular orbitals which enables efficient nanosecond-scale luminescence in these materials due to the spin-allowed transitions between doublet-spin states. In this review, we summarize recent advances in these materials and their application in organic light emitting diodes (OLEDs). The photoluminescence and electroluminescence mechanisms of different doublet-emissive molecular systems are discussed, in addition to the photophysical phenomena arising from doublet states. We also outline the current challenges faced by each molecular system, and the potential outlook on the future research trends in this field.

Photo-induced Ultrafast Charge Transfer and Air-Stable Radical Formation in Tetraphenylpyrene Derivatives.

Stable organic radicals generated by photo-excitation hold applications in molecular switching devices and information storage. It remains challenging to develop photo-generated radical materials with rapid response and air stability in the solid state. Here, we report a structure based on 1,3,6,8-tetraphenylpyrene derivative (Py-TTAc) displaying photo-induced radicals with air stability in the solid state. Photo-induced electron transfer, exposed to a 365 nm ultraviolet lamp for 1 minute, affords radicals in Py-TTAc powder as confirmed by electron paramagnetic resonance (EPR) spectroscopy. The maximum radical concentration reaches 2.21% after continuous irradiation for 1 hour and recurs more than 10 times without any chemical degradation. The mechanistic study according to the femtosecond transient absorption (fsTA) and X-ray technology suggests that the radicals are derived from photo-induced symmetry-breaking charge separation (SB-CS) and stabilized through non-covalent interactions. The photo-generated stable radical system is employed in anti-counterfeiting paper and optoelectronic device applications. This study will provide insights into the development of photoactive organic radical materials.

Improving the Luminescence and Stability of Carbon-Centered Radicals by Kinetic Isotope Effect.

The kinetic isotope effect (KIE) is beneficial to improve the performance of luminescent molecules and relevant light-emitting diodes. In this work, the influences of deuteration on the photophysical property and stability of luminescent radicals are investigated for the first time. Four deuterated radicals based on biphenylmethyl, triphenylmethyl, and deuterated carbazole were synthesized and sufficiently characterized. The deuterated radicals exhibited excellent redox stability, as well as improved thermal and photostability. The appropriate deuteration of relevant C-H bonds would effectively suppress the non-radiative process, resulting in the increase in photoluminescence quantum efficiency (PLQE). This research has demonstrated that the introduction of deuterium atoms could be an effective pathway to develop high-performance luminescent radicals.

A novel structurally identified epitope delivered by macrophage membrane-coated PLGA nanoparticles elicits protection against Pseudomonas aeruginosa.

The increasing prevalence of antibiotic resistance by Pseudomonas aeruginosa (PA) raises an urgent need for an effective vaccine. The outer membrane proteins of PA, especially those that are upregulated during infection, are ideal vaccine targets. However, the strong hydrophobicity of these proteins hinders their application for this purpose. In this study, we selected eight outer membrane proteins from PA with the most significantly upregulated expression. Their extracellular loops were analyzed and screened by using sera from patients who had recovered from PA infection. As a result, a novel immunogenic epitope (Ep167-193) from PilY1 (PA4554) was found. Moreover, we constructed a macrophage membrane-coated PLGA (poly lactic-co-glycolic acid) nanoparticle vaccine carrying PilY1 Ep167-193 (PNPs@M-Ep167-193) that elicits a Th2 immune response and confers adequate protection in mice. Our data furnished the promising vaccine candidate PNPs@M-Ep167-193 while providing additional evidence for structure-based epitope identification and vaccine design.

Effects of demographic, audiologic, and hearing-aid-related variables on the outcomes of using hearing aids.

PURPOSE: To examine the influence of demographic, audiologic, and hearing-aid (HA)-related variables on HA outcomes. METHODS: In total, 235 adults with hearing loss (HL) who used HAs for at least 3 months were included in the study, and completed audiologic tests and the Chinese version of the International Outcome Inventory for Hearing Aids (IOI-HA). Spearman correlation analysis and Wilcoxon test were conducted to identify factors related to IOI-HA overall and subscales scores. Stepwise multiple linear regression analysis was subsequently performed to determine the influence of factors on HA outcomes. RESULTS: Age, daily use time, HA price, pure tone average (PTA) threshold, word recognition score (WRS), fitting (bilateral or unilateral), and HA style were associated with IOI-HA overall and subscales scores. However, only WRS, daily HA use time, HA price, and age entered the final regression model and were factors determining HA outcomes. CONCLUSIONS: HA outcome is a multi-dimensional construct. In this study, WRS had the greatest influence on HA outcomes and seemed to be a primary predictor. Thus, HA owners with a higher WRS before HA fitting may indicate better satisfaction. Daily use time, HA price, and patient age also made significant contributions to HA outcomes and should be considered in clinical practice to facilitate auditory rehabilitation.

Retracted: Knockdown of MicroRNA-122 Protects H9c2 Cardiomyocytes from Hypoxia-Induced Apoptosis and Promotes Autophagy.

This publication has been retracted by the Editor due to the identification of non-original figure images and manuscript content that raise concerns regarding the credibility and originality of the study and the manuscript.Reference:Zaiwei Zhang, Hu Li, Shasha Chen, Ying Li, Zhiyuan Cui, Jie Ma. Knockdown of MicroRNA-122 Protects H9c2 Cardiomyocytes from Hypoxia-Induced Apoptosis and Promotes Autophagy. Med Sci Monit, 2017; 23: 4284-4290. DOI: 10.12659/MSM.902936.

Knockdown of MicroRNA-122 Protects H9c2 Cardiomyocytes from Hypoxia-Induced Apoptosis and Promotes Autophagy.

BACKGROUND Acute myocardial infarction (AMI) is a severe disease causing heart failure and sudden death. Studies indicate that microRNAs (miRNAs) are involved in the pathophysiology of AMI. In the present study, we carefully explored the effects of miR-122 on myocardial hypoxia injury and its possible underlying mechanism. MATERIAL AND METHODS miR-122 expression was analyzed in H9c2 cardiomyocytes after being transfected with miR-122 mimic, ASO-miR-122, or negative control. Cell viability and apoptosis were investigated by CCK-8 assays and flow cytometry analysis, respectively. Cell migration was analyzed using wound-healing assays. Western blotting was performed to analyze the expression of phosphatase and tensin homolog deleted on chromosome 10 (PTEN)/phosphatidylinositol 3-hydroxy kinase (PI3K)/AKT and LC3-II/LC3-I. RESULTS Hypoxia exposure significantly inhibited H9c2 cell viability (P<0.01). miR-122 overexpression promoted the hypoxia-induced H9c2 cell proliferation and migration loss (P<0.05), and cell apoptosis was increased (P<0.05). miR-122 knockdown enhanced cell viability and decreased cell apoptosis (P<0.05). Knockdown of miR-122 enhanced PTEN/PI3K/AKT activation and cell autophagy. Overexpression of miR-122 inhibited the PTEN/PI3K/AKT pathway and cell autophagy pathway. CONCLUSIONS The expression of miR-122 is involved in hypoxia-induced H9c2 cardiomyocyte injury. Knockdown of miR-122 protects H9c2 cells from hypoxia-induced apoptosis and enhances cell viability.

Towards Efficient and Stable Donor-Acceptor Luminescent Radicals.

In contrast to closed-shell luminescent molecules, the electronic ground state and lowest excited state in organic luminescent radicals are both spin doublet, which results in spin-allowed radiative transitions. Most reported luminescent radicals with high photoluminescent quantum efficiency (PLQE) have a donor-acceptor (D-A•) chemical structure where an electron-donating group is covalently attached to an electron-withdrawing radical core (A•). Understanding the main factors that define the efficiency and stability of D-A• type luminescent radicals remains challenging. Here, we designed and synthesized a series of tri(2,4,6-trichlorophenyl)methyl (TTM) radical derivatives with donor substituents varying by their extent of conjugation and their number of imine-type nitrogen atoms. The experimental results suggest that the luminescence efficiency and stability of the radicals are proportional to the degree of conjugation but inversely proportional to the number of imine nitrogen atoms in the substituents. These experimental trends are very well reproduced by density functional theory calculations. The theoretical results indicate that both the luminescence efficiency and radical stability are related to the energy difference between the charge transfer (CT) and local-excitation (LE) states, which decreases as either the number of imine nitrogen atoms in the substituent increases or its conjugation length decreases.

Sulfur vacancy regulation and multipolarization of NixCo1S nanowires-decorated biotemplated structures to promote microwave absorption.

It is a novel and practical method to use natural porous biomaterials as microwave absorber. In this study, NixCo1S nanowires (NWs)@diatomite (De) composites with one-dimensional (1D)-NWs and three-dimensional(3D)-De composites were prepared by a two-step hydrothermal method using De as template. The effective absorption bandwidth (EAB) of the composite reaches 6.16 GHz at 1.6 mm and 7.04 GHz at 4.1 mm, covering the entire Ku band, and the minimum reflection loss (RLmin) is less than -30 dB. The excellent absorption performance is mainly due to the bulk charge modulation provided by the 1D NWs and the extended microwave transmission path within the absorber, coupled with the high dielectric loss and magnetic loss of the metal-NWS after vulcanization. We present a high-value method that combines vulcanized 1D materials with abundant De to achieve the lightweight broadband efficient microwave absorption at the first time.

Investigation on the adsorption and transport properties of lithium ion in the covalent organic framework/carbon nanotube composite by molecular simulation.

Aimed at the exploration of novel electrode materials for lithium ion batteries (LIBs), this work investigated by molecular simulation the adsorption and transport properties of lithium ion (Li+) in the composite materials formed by covalent organic frameworks (COFs) separately with single-walled carbon nanotubes (SWCNTs) and double-walled carbon nanotubes (DWCNTs) (COF@SWCNT, COF@DWCNT). Results show that all the Li+ adsorption processes can be divided into five stages, of which the most stable is the first stage on the nitrogen site. During the adsorption processes, the maximum volumetric change rates of COF@SWCNT and COF@DWCNT are separately 0.25 and 0.29, and their average voltages can be maintained above 2.00 V and 2.50 V, respectively. In addition, the Li+ conductivities inside the COF@SWCNT and the COF@DWCNT are both greater than the experimental data of a simple SWCNT. It can be seen that both of the COF@SWCNT and the COF@DWCNT can meet the basic requirements of LIBs electrode materials, and the increase in the layer number of CNTs is conducive to improving the average voltage and the Li+ conductivity of the composite. More importantly, the origin of corresponding synergistic effects can be preliminarily confirmed through quantum mechanics calculations. This work may pave the way to the development of composite electrode materials for LIBs.

Intranasal Vaccination with rePcrV Protects against Pseudomonas aeruginosa and Generates Lung Tissue-Resident Memory T Cells.

Tissue-resident memory T (TRM) cells are immune sentinels that bear a key role in the local immune system and rapidly respond to infection. Our previous studies showed that mucosal immunization via intranasal pathways was more effective than intramuscular route. However, the mechanism of enhanced protective immunity remains unclear. Here, we formulated a Pseudomonas aeruginosa vaccine composed of type III secretion protein PcrV from P. aeruginosa and curdlan adjuvant and then administered by the intranasal route. Flow cytometry and immunofluorescence staining showed that the ratio of CD44+CD62L-CD69+CD4+ TRM cells induced by this vaccine was significantly increased, and IL-17A production was notably enhanced. Further analysis revealed that vaccinated mice can protect against the P. aeruginosa challenge even after administration with FTY720 treatment. What is more, our results showed that CD4+ TRM might be involved in the recruitment of neutrophils and provided partial protection against Pseudomonas aeruginosa. Taken together, these data demonstrated that CD4+ TRM cells were elicited in lung tissues after immunization with rePcrV and contributed to protective immunity. Furthermore, it provided novel strategies for the development of vaccines for P. aeruginosa and other respiratory-targeted vaccines.

Ultrafast-response, highly-sensitive and recyclable colorimetric/fluorometric dual-channel chemical warfare agent probes.

In this paper, two donor (D)-acceptor (A) type of small organic fluorescent molecules (T1 and T2) based on terpyridine group are synthesized, characterized and used as colorimetric/fluorometric dual-channel probes towards diethylchlorophosphate (DCP, the mimic of chemical warfare agent sarin) not only in solution but also in gas phase featuring instantaneous responses, excellent recyclability, high selectivity and sensitivity. Interestingly though the discriminated units of both chemosensors are terpyridine, their fluorescent responded signals are different, which is due to the different electron-donating substituents of T1 and T2 caused the different responded mechanism to DCP. And the possible sensing mechanism was proved by using nuclear magnetic resonance (1H NMR, 31P NMR) spectra and natural transition orbitals calculations. Furthermore, facile testing filter paper-constructed strips with the visualization of colorimetric/fluorometric dual-channel responses based on T1 and T2 have been fabricated for real-time, on-site high selective and sensitive, recyclable monitor of DCP vapor.

Long non-coding RNA UCA1 relieves cardiomyocytes H9c2 injury aroused by oxygen-glucose deprivation via declining miR-122.

Background: Many lncRNAs have been recognized as critical regulatory factors in acute myocardial infarction (AMI). Herein, we further tested the influence of long non-coding RNA urothelial carcinoma associated 1 (UCA1) on cardiomyocytes injury in AMI, along with the role of microRNA-122 (miR-122) in this influence. Methods: Cardiomyocytes H9c2 was subjected to oxygen-glucose deprivation (OGD) stimulation. Cell viability and apoptosis were assessed. The UCA1 and miR-122 expressions were measured by qRT-PCR. Plasmids and miRNAs transfection were utilized to elevate UCA1 and miR-122 expressions. Subsequently, the influences of UCA1 and/or miR-122 overexpression on OGD-aroused H9c2 cell viability inhibition and apoptosis were probed. The AKT/mTOR and JNK/p38MAPK pathways in cells were analyzed. Results: OGD aroused H9c2 cell injury by suppressing cell viability and elevating cell apoptosis. Followed by OGD stimulation, the UCA1 expression was lowered in H9c2 cells. Overexpression of UCA1 weakened H9c2 cell injury aroused by OGD and declined miR-122 expression. Moreover, miR-122 attended to the influence of UCA1 overexpression on OGD-aroused H9c2 cell injury. Overexpression of UCA1 weakened OGD-aroused AKT/mTOR pathway inactivation and JNK/p38MAPK pathway activation by declining miR-122. Conclusion: UCA1-relieved OGD-aroused H9c2 cell injury might be achieved via declining miR-122 and then promoting AKT/mTOR pathway and suppressing JNK/p38MAPK pathway.

Lycium barbarum polysaccharides protects H9c2 cells from hypoxia-induced injury by down-regulation of miR-122.

BACKGROUND: Lycium barbarum polysaccharides (LBPs) are major ingredients of fructus lycii, which have multiple pharmacological activities, such as antioxidant, neuroprotective, and anti-inflammatory activities. This study attempted to reveal the potential of LBPs in hypoxia-injured H9c2 cells and the possible underlying mechanisms. METHODS: H9c2 cells were treated by 300 µg/mL LBPs for 24 h upon hypoxia. Subsequently, the changes in cell viability, migration and apoptosis were evaluated. pre-miR-122 or miR-122 sponge was transfected into H9c2 cells to investigate whether miR-122 was involved in the mechanisms of LBPs' action. Besides, an animal model of myocardial infarction (MI) was established, and the in vivo effects of LBPs were further investigated. RESULTS: LBPs increased cell viability, down-regulated p53, p21 and p16 protein expressions, improved migration, and repressed apoptosis in hypoxia-injured H9c2 cells. miR-122 was highly expressed in response to hypoxia, while was down-regulated by addition of LBPs. The protective actions of LBPs in hypoxia-injured H9c2 cells were attenuated by miR-122 overexpression, while were accelerated by miR-122 suppression. Also, LBPs-induced the activation of MEK/ERK and AMPK signaling pathways were attenuated by miR-122 overexpression, and were accelerated by miR-122 suppression. in vivo investigation revealed that, MI rats administrated with LBPs decreased infarct size and improved cardiac function via down-regulation of miR-122. CONCLUSION: LBPs exhibited in vitro and in vivo cardioprotective activities via down-regulating miR-122. LBPs may have potential for the treatment of acute myocardial infarction (AMI).

miR-140-5p aggravates hypoxia-induced cell injury via regulating MLK3 in H9c2 cells.

Myocardial infarction (MI) is an important cause of cardiovascular disease. microRNAs (miRNAs) have been indicated as pivotal regulators in the physiological and pathological processes of heart diseases. The purpose of this study was to investigate the role of miR-140-5p in hypoxia-induced cell injury in H9c2 cells and its underlying mechanism. H9c2 cells were subjected to hypoxia, before which the expression levels of miR-140-5p and MLK3 were overexpressed or knocked down through transient transfection. The efficiency of transfection was verified by qRT-PCR and Western blotting. Cell viability, apoptotic cell rate, and the expression changes of apoptosis-related proteins were determined by trypan blue exclusion, flow cytometry, and Western blotting, respectively. Furthermore, Western blotting was performed to assess the expression levels of core factors related with p38MAPK and JNK signaling pathways. As a result, hypoxia significantly reduced cell viability and increased cell apoptosis in H9c2 cells. miR-140-5p inhibition attenuated cell injury induced by hypoxia in H9c2 cells, while miR-140-5p overexpression expedited the cell injury, as evidenced by the decreased cell viability and enhanced cell apoptosis. Moreover, miR-140-5p promoted the activation of p38MAPK and JNK pathways. miR-140-5p positively modulated the expression of MLK3. ML3 overexpression reversed the regulatory effects of miR-140-5p inhibition on hypoxia-injured H9c2 cells. In conclusion, this study demonstrated that miR-140-5p aggravated hypoxia-induced cell injury partially through up-regulation of MLK3.

Radical-Based Organic Light-Emitting Diodes with Maximum External Quantum Efficiency of 10.6.

A new luminescent radical, tris-2,4,6-trichlorophenylmethyl-1,5-diazarcarbazole (TTM-DACz), was synthesized and characterized. The photoluminescence quantum yield of TTM-DACz in solid 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene matrix film (5 wt %) is as high as 57.0%. Organic light-emitting diodes (OLEDs) employing TTM-DACz as the emitter were fabricated. By rational design of the device structure and host-guest doping system, external quantum efficiency (EQE) of up to 10.6% of the optimized device with a red CIE chromaticity of (0.62, 0.36) was obtained, which is among the highest values for red OLEDs using nonphosphorescent materials as the emitters. This work will accelerate the development of luminescent radical materials for high-performance OLEDs.

Comprehensive transcriptome analysis of developing xylem responding to artificial bending and gravitational stimuli in Betula platyphylla.

Betula platyphylla Suk (birch) is a fast-growing woody species that is important in pulp industries and the biofuels. However, as an important pulp species, few studies had been performed on its wood formation. In the present study, we investigated the molecular responses of birch xylem to artificial bending and gravitational stimuli. After trunks of birch trees were subjected to bending for 8 weeks, the cellulose content was significantly greater in tension wood (TW) than in opposite wood (OW) or normal wood (NW), whereas the lignin content in TW was significantly lower than that in OW and NW. In addition, TW grew more rapidly than OW and generated TW-specific fibers with an additional G-layer. Three transcriptome libraries were constructed from TW, OW and NW of B. platyphylla, respectively, after the plants were subjected to artificial bending. Overall, 80,909 nonredundant unigenes with a mean size of 768 nt were assembled. Expression profiles were generated, and 9,684 genes were found to be significantly differentially expressed among the TW, OW and NW libraries. These included genes involved in secondary cell wall structure, wood composition, and cellulose or lignin biosynthesis. Our study showed that during TW formation, genes involved in cellulose synthesis were induced, while the expression of lignin synthesis-related genes decreased, resulting in increased cellulose content and decreased lignin levels in TW. In addition, fasciclin-like arabinogalactan proteins play important role in TW formation. These findings may provide important insights into wood formation at the molecular level.