Scintillators are widely utilized for radiation detections in many fields, such as nondestructive inspection, medical imaging, and space exploration. Lead halide perovskite scintillators have ...recently received extensive research attention owing to their tunable emission wavelength, low detection limit, and ease of fabrication. However, the low light yields toward X‐ray irradiation and the lead toxicity of these perovskites severely restricts their practical application. A novel lead‐free halide is presented, namely Rb2CuBr3, as a scintillator with exceptionally high light yield. Rb2CuBr3 exhibits a 1D crystal structure and enjoys strong carrier confinement and near‐unity photoluminescence quantum yield (98.6%) in violet emission. The high photoluminescence quantum yield combined with negligible self‐absorption from self‐trapped exciton emission and strong X‐ray absorption capability enables a record high light yield of ≈91056 photons per MeV among perovskite and relative scintillators. Overall, Rb2CuBr3 provides nontoxicity, high radioluminescence intensity, and good stability, thus laying good foundations for potential application in low‐dose radiography.
A new lead‐free halide Rb2CuBr3 scintillator with 1D crystal structure is presented. It exhibits self‐trapped exciton emission with a large Stokes shift (0.91 eV). Thus, it has near‐unity photoluminescence quantum yield (98.6%) and a high radioluminescence light yield of ≈91 056 photons per MeV.
In this study, acoustic emission (AE) analysis method was applied to monitor the damage evolution process of ultra high performance concrete (UHPC) under direct tensile test. Three types of UHPCs, ...including high strain-hardening UHPC, low strain-hardening UHPC and strain-softening UHPC were investigated. Meanwhile, the crack width developments of UHPCs during the tensile test were measured. Test results show that high strain-hardening UHPC exhibited high ductility by forming multiple microcracks invisible to naked eyes (typically below 0.05 mm) in the strain-hardening stage. The crack width-strain curves indicate that increasing the ultimate tensile strain of UHPC can improve its crack width control ability effectively. The AE analysis method could effectively detect the internal damages of the high strain-hardening UHPC at a strain of 600με. At that time, the crack width was smaller than 0.01 mm that could not be detected by crack width measuring instrument in this study. For three types of UHPCs, damages were generated around the localized crack during the strain-softening stage. In a word, the AE analysis method provides strong evidence to the multiple cracking behavior of UHPC during the strain-hardening stage, and provides a clear explanation to the identical damage evolution mechanism for three types of UHPCs during the strain-softening stage.
Pyroptosis is a pro-inflammatory form of regulated cell death and is dependent on the enzymatic activity of inflammatory proteases that belong to the family of cysteine-dependent aspartate-specific ...proteases (caspases). Pyroptosis is morphologically, mechanistically, and pathophysiologically distinct from other forms of cell death, including apoptosis and necrosis. Pyroptosis is characterized by rapid plasma membrane rupture, with the consequent release of intracellular contents and pro-inflammatory mediators, including interleukin (IL)-1β, IL-18, and the alarmin HMGB-1.Recent studies have shown that pyroptosis may be involved in atherosclerosis and play an important role in atherosclerotic lesion instability. Here, we review the progress made in understanding the morphological, molecular, and pathophysiological mechanisms of pyroptosis and its potential role in atherosclerosis.
Backscattering suppression in silicon-on-insulator (SOI) is one of the central issues to reduce energy loss and signal distortion, enabling for capability improvement of modern information processing ...systems. Valley physics provides an intriguing way for robust information transfer and unidirectional coupling in topological nanophotonics. Here we realize topological transport in a SOI valley photonic crystal slab. Localized Berry curvature near zone corners guarantees the existence of valley-dependent edge states below light cone, maintaining in-plane robustness and light confinement simultaneously. Topologically robust transport at telecommunication is observed along two sharp-bend interfaces in subwavelength scale, showing flat-top high transmission of ~10% bandwidth. Topological photonic routing is achieved in a bearded-stack interface, due to unidirectional excitation of valley-chirality-locked edge state from the phase vortex of a nanoscale microdisk. These findings show the prototype of robustly integrated devices, and open a new door towards the observation of non-trivial states even in non-Hermitian systems.
Nucleic acids from bacteria or viruses induce potent immune responses in infected cells
. The detection of pathogen-derived nucleic acids is a central strategy by which the host senses infection and ...initiates protective immune responses
. Cyclic GMP-AMP synthase (cGAS) is a double-stranded DNA sensor
. It catalyses the synthesis of cyclic GMP-AMP (cGAMP)
, which stimulates the induction of type I interferons through the STING-TBK1-IRF-3 signalling axis
. STING oligomerizes after binding of cGAMP, leading to the recruitment and activation of the TBK1 kinase
. The IRF-3 transcription factor is then recruited to the signalling complex and activated by TBK1
. Phosphorylated IRF-3 translocates to the nucleus and initiates the expression of type I interferons
. However, the precise mechanisms that govern activation of STING by cGAMP and subsequent activation of TBK1 by STING remain unclear. Here we show that a conserved PLPLRT/SD motif within the C-terminal tail of STING mediates the recruitment and activation of TBK1. Crystal structures of TBK1 bound to STING reveal that the PLPLRT/SD motif binds to the dimer interface of TBK1. Cell-based studies confirm that the direct interaction between TBK1 and STING is essential for induction of IFNβ after cGAMP stimulation. Moreover, we show that full-length STING oligomerizes after it binds cGAMP, and highlight this as an essential step in the activation of STING-mediated signalling. These findings provide a structural basis for the development of STING agonists and antagonists for the treatment of cancer and autoimmune disorders.
Two‐dimensional layered graphene‐like crystals including transition‐metal dichalcogenides (TMDs) have received extensive research interest due to their diverse electronic, valleytronic, and chemical ...properties, with the corresponding optoelectronics and catalysis application being actively explored. However, the recent surge in two‐dimensional materials science is accompanied by equally great challenges, such as defect engineering in large‐scale sample synthesis. It is necessary to elucidate the effect of structural defects on the electronic properties in order to develop an application‐specific strategy for defect engineering. Here, two aspects of the existing knowledge of native defects in two‐dimensional crystals are reviewed. One is the point defects emerging in graphene and hexagonal boron nitride, as probed by atomically resolved electron microscopy, and their local electronic properties, as measured by single‐atom electron energy‐loss spectroscopy. The other will focus on the point defects in TMDs and their influence on the electronic structure, photoluminescence, and electric transport properties. This review of atomic defects in two‐dimensional materials will offer a clear picture of the defect physics involved to demonstrate the local modulation of the electronic properties and possible benefits in potential applications in magnetism and catalysis.
Single‐atom defects are systematically reviewed in two‐dimensional material systems such as graphene, BN, and transition‐metal dichalcogenides. The local atomic arrangement and associated electronic structure are probed by transmission electron microscopy and single‐atom spectroscopy, and the influence from the defects on the macroscopic functionalities of two‐dimensional materials is discussed, focusing mostly on electronics, photonics, nanomagnetism, and catalysis.
The clinical features and immune responses of asymptomatic individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have not been well described. We studied 37 ...asymptomatic individuals in the Wanzhou District who were diagnosed with RT-PCR-confirmed SARS-CoV-2 infections but without any relevant clinical symptoms in the preceding 14 d and during hospitalization. Asymptomatic individuals were admitted to the government-designated Wanzhou People's Hospital for centralized isolation in accordance with policy
. The median duration of viral shedding in the asymptomatic group was 19 d (interquartile range (IQR), 15-26 d). The asymptomatic group had a significantly longer duration of viral shedding than the symptomatic group (log-rank P = 0.028). The virus-specific IgG levels in the asymptomatic group (median S/CO, 3.4; IQR, 1.6-10.7) were significantly lower (P = 0.005) relative to the symptomatic group (median S/CO, 20.5; IQR, 5.8-38.2) in the acute phase. Of asymptomatic individuals, 93.3% (28/30) and 81.1% (30/37) had reduction in IgG and neutralizing antibody levels, respectively, during the early convalescent phase, as compared to 96.8% (30/31) and 62.2% (23/37) of symptomatic patients. Forty percent of asymptomatic individuals became seronegative and 12.9% of the symptomatic group became negative for IgG in the early convalescent phase. In addition, asymptomatic individuals exhibited lower levels of 18 pro- and anti-inflammatory cytokines. These data suggest that asymptomatic individuals had a weaker immune response to SARS-CoV-2 infection. The reduction in IgG and neutralizing antibody levels in the early convalescent phase might have implications for immunity strategy and serological surveys.
Metal halide perovskites and derivatives exhibit a high sensitivity and low detection limit as direct X‐ray detectors. Inorganic 2D bismuth halide perovskites are promising for X‐ray detections, but ...have not been reported. Moreover, the quantitative relationship between the structural dimensionality of A3B2X9 perovskites and their compositions has never been investigated, and the underlying mechanism is unclear. Here, the key structural descriptors for 2D A3B2X9 perovskite derivatives are reported: i) octahedral factor μ, 0.377 < μ < 0895; ii) tolerance factor t, 0.8 < t < 1.06; iii) (rA‐0.55)/t < 1.48 Å. Accordingly, a new 2D A3B2X9 perovskite derivative, Rb3Bi2I9, with high X‐ray attenuation coefficients is found. The assembled X‐ray detector exhibits a high μτ product of 2.51 × 10−3 cm2 V−1, good sensitivity for 159.7 μC Gyair−1 cm−2, and a record low detection limit of 8.32 nGyair s−1 among all direct and indirect perovskite X‐ray detectors. The device also exhibits good stability toward external bias and continuous gamma ray radiations (480 000 Gy). This work provides crystal structural insights to rationally design 2D perovskites for new types of radiation detectors.
The key structural descriptors are reported for 2D A3B2X9 perovskite derivatives. By following the above designing rules, Rb3Bi2I9 is assembled into an X‐ray detector, exhibiting a low detection limit of 8.32 nGyair s−1 and suppressed ions migration. The inorganic composition also guarantees excellent stability toward continuous radiation from the 60Co source.
All‐solid‐state donor/acceptor planar‐heterojunction (PHJ) hybrid solar cells are constructed and their excellent performance measured. The deposition of a thin C60 fullerene or fullerene‐derivative ...(acceptor) layer in vacuum on a CH3NH3PbI3 perovskite (donor) layer creates a hybrid PHJ that displays the photovoltaic effect. Such heterojunctions are shown to be suitable for the development of newly structured, hybrid, efficient solar cells.
Atherosclerosis is a progressive, chronic inflammation in arterial walls. Long noncoding RNAs (lncRNAs) participate in inflammation, but the exact mechanism in atherosclerosis is unclear. Our ...microarray analyses revealed that the levels of lncRNA-FA2H-2 were significantly decreased by oxidized low-density lipoprotein (OX-LDL). Bioinformatics analyses indicated that mixed lineage kinase domain-like protein (MLKL) might be regulated by lncRNA-FA2H-2. In vitro experiments showed that lncRNA-FA2H-2 interacted with the promoter of the MLKL gene, downregulated MLKL expression, and the binding sites between -750 and 471 were necessary for lncRNA-FA2H-2 responsiveness to MLKL. Silencing lncRNA-FA2H-2 and overexpression of MLKL could activate inflammation and inhibited autophagy flux. Both lncRNA-FA2H-2 knockdown and overexpression of MLKL could significantly aggravate inflammatory responses induced by OX-LDL. We found that the 3-methyladenine (3-MA) and Atg7-shRNA enhanced inflammatory responses induced by knockdown of lncRNA-FA2H-2 and overexpression of MLKL. We demonstrated that the effects of MLKL on autophagy might be associated with a mechanistic target of rapamycin (mTOR)-dependent signaling pathways. In vivo experiments with apoE knockout mice fed a western diet demonstrated that LncRNA-FA2H-2 knockdown decreased microtubule-associated expression of microtubule-associated protein 1 light chain 3 II and lysosome-associated membrane protein 1, but increased expression of sequestosome 1 (p62), MLKL, vascular cell adhesion molecule-1, monocyte chemoattractant protein-1, and interleukin-6 in atherosclerotic lesions. Our findings indicated that the lncRNA-FA2H-2-MLKL pathway is essential for regulation of autophagy and inflammation, and suggested that lncRNA-FA2H-2 and MLKL could act as potential therapeutic targets to ameliorate atherosclerosis-related diseases.
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