Many important energy-transfer and optical processes, in both biological and artificial systems, depend crucially on excitonic coupling that spans several chromophores. Such coupling can in principle ...be described in a straightforward manner by considering the coherent intermolecular dipole-dipole interactions involved. However, in practice, it is challenging to directly observe in real space the coherent dipole coupling and the related exciton delocalizations, owing to the diffraction limit in conventional optics. Here we demonstrate that the highly localized excitations that are produced by electrons tunnelling from the tip of a scanning tunnelling microscope, in conjunction with imaging of the resultant luminescence, can be used to map the spatial distribution of the excitonic coupling in well-defined arrangements of a few zinc-phthalocyanine molecules. The luminescence patterns obtained for excitons in a dimer, which are recorded for different energy states and found to resemble σ and π molecular orbitals, reveal the local optical response of the system and the dependence of the local optical response on the relative orientation and phase of the transition dipoles of the individual molecules in the dimer. We generate an in-line arrangement up to four zinc-phthalocyanine molecules, with a larger total transition dipole, and show that this results in enhanced 'single-molecule' superradiance from the oligomer upon site-selective excitation. These findings demonstrate that our experimental approach provides detailed spatial information about coherent dipole-dipole coupling in molecular systems, which should enable a greater understanding and rational engineering of light-harvesting structures and quantum light sources.
Bisphenol A (BPA), a chemical widely used in the manufacture of polycarbonate plastics, has raised considerable concern in recent decades because of its hormone-like properties. Whether BPA exposure ...is a health risk remains controversial in many countries. A metabolomics study based on capillary electrophoresis time-of-flight mass spectrometry (CE-TOF/MS) was performed to study the urine metabolic profiles of Sprague–Dawley rats fed with four dose levels of BPA (0, 1, 10, and 100 μg/kg body weight) for 45 days. Multivariate pattern recognition directly reflected the metabolic perturbations caused by BPA. On the basis of univariate analysis, 42 metabolites including amino acids, polyamines, nucleosides, organic acids, carbohydrates, pterins, polyphenols, and sugar phosphates were found as the most significantly differential metabolites. The marked perturbations were related with valine, leucine and isoleucine biosynthesis, d-glutamine and d-glutamate metabolism, etc. Significant alterations of neurotransmitters (glutamate, gamma-aminobutyric acid, and noradrenaline) and neurotransmitter-related metabolites (tyrosine, histamine, valine, and taurine) suggested that the toxic effects of small-dose BPA (below 50 mg/kg/day) may contribute to its interactions with the neuromediating system. Our study demonstrated that metabolomics may offer more specific insights into the molecular changes underlying the physiological effects of BPA.
Innervation and extracellular vesicle secretion co‐exist in the local tissue microenvironment for message transfer, but whether they are interconnected to regulate organ homeostasis remains unknown. ...Sympatho‐adrenergic activation is implicated in stress‐induced depression and leads to bone loss, but the mechanisms and therapeutics are incompletely elucidated. Here, it is revealed that sympathetic neurostress through the β1/2‐adrenergic receptor (β1/2‐AR) signaling triggers the transcription response of a microRNA, miR‐21, in osteoblasts, which is transferred to osteoclast progenitors via exosomes for dictating osteoclastogenesis. After confirming that miR‐21 deficiency retards the β1/2‐AR agonist isoproterenol (ISO)‐induced osteopenia, it is shown that the pharmacological inhibition of exosome release by two clinically‐relevant drugs, dimethyl amiloride and omeprazole, suppresses osteoblastic miR‐21 transfer and ameliorates bone loss under both ISO and chronic variable stress (CVS)‐induced depression conditions. A targeted delivery approach to specifically silence osteoblastic miR‐21 is further applied, which is effective in rescuing the bone remodeling balance and ameliorating ISO‐ and CVS‐induced osteopenias. These results decipher a previously unrecognized paradigm that neural cues drive exosomal microRNA communication to regulate organ homeostasis and help to establish feasible strategies to counteract bone loss under psychological stresses.
It was discovered that sympatho‐adrenergic cues provoke transcription response of miR‐21 in osteoblasts, which is transferred via exosomes to dictate osteoclastogenesis and disrupt bone homeostasis. It is further shown that pharmacological inhibition of exosome release by clinically‐relevant drugs, dimethyl amiloride or omeprazole, and targeted delivery of antagomir‐21 to osteoblasts are effective in ameliorating osteopenias against isoproterenol and depression stresses.
A self-decoupled porphyrin with a tripodal anchor has been synthesized and deposited on Au(111) using different wet-chemistry methods. Nanoscale electroluminescence from single porphyrin molecules or ...aggregates on Au(111) has been realized by tunneling electron excitation. The molecular origin of the luminescence is established by the vibrationally resolved fluorescence spectra observed. The rigid tripodal anchor not only acts as a decoupling spacer but also controls the orientation of the molecule. Intense molecular electroluminescence can be obtained from the emission enhancement provided by a good coupling between the molecular transition dipole and the axial nanocavity plasmon. The unipolar performance of the electroluminescence from the designed tripodal molecule suggests that the porphyrin molecule is likely to be excited by the injection of hot electrons, and then the excited state decays radiatively through Franck–Condon π*−π transitions. These results open up a new route to generating electrically driven nanoscale light sources.
Purpose. Manganese-enhanced MRI (MEMRI) has been applied to a wide range of biological and disease research. The purpose of the study was to use MEMRI to diagnose the acute mesenteric ischemia (AMI). ...Methods. The institutional experimental animal ethics committee approved this study. To optimize the dose of Mn2+ infusion, a dose-dependent curve was obtained using Mn2+-enhanced T 1 map MRI by an intravenous infusion 2.5–20 nmol/g body weight (BW) of 50 nmol/L MnCl2. The eighteen animals were divided into control, sham-operated, and AMI groups. AMI models were performed by ligating the superior mesenteric artery (SMA). T 1 values were measured on T 1 maps in regions of the small intestinal wall and relaxation rate (ΔR 1) was calculated. Results. A nonlinear relationship between infused MnCl2 solution dose and increase in small intestinal wall ΔR 1 was observed. Control animal exhibited significant Mn2+ clearance over time at the dose of 15 nmol/g BW. In the AMI model, ΔR 1 values (0.95 ± 0.13) in the small intestinal wall were significantly lower than in control group (2.05 ± 0.19) after Mn2+ infusion (P < 0.01). Conclusion. The data suggest that MEMRI shows potential as a diagnostic technique that is directly sensitive to the poor or absent perfusion in AMI.
Automatic Dependent Surveillance-Broadcast (ADS-B) is an International Civil Aviation Organization (ICAO) formally identified and promoted mainstream surveillance methods of the future. However, the ...increasing airspace traffic density makes overlapping a serious problem. In order to separate the overlapped ADS-B signals in time domain, orthogonal projection algorithms are carried out for different antenna situations. Firstly, Singular Value Decomposition (SVD) is used to determine the position of overlapped signals. Then, for antenna arrays, Projection Algorithm (PA) is used to separate the overlapped signals. For single antenna, Projection Algorithm Single Antenna (PASA) is used. Last, the separated signals are compared and verified.
We presented in this article an in situ electromigration behavior in a novel Cu tall pillar/Cu via interconnect. A Cu tall pillar connecting to a single Cu via for joining the fan-out Cu ...redistribution lines (RDLs) was introduced for high-power device applications. The novelty of this study was to design a special ladder-shaped Cu tall pillar for the purpose of the fan-out effect of high-density electric current. The in situ SEM (scanning electron microscope) microstructure investigation during the electromigration experiment provided interesting information for the reliability evaluation and in-depth mechanism exploration of the electromigration behavior in the novel Cu interconnect. A stepwise electromigration experiment was conducted at an initial 2.5 A electric current, approximately 10 5 to 10 6 A/cm 2 current density for the components in the Cu interconnect, followed by a larger current input of 3 A. Electrons flowed from the fan-out Cu RDL (cathode) through the Cu via to the Cu tall pillar and the connecting Cu line (anode). The investigations revealed the dynamic void nucleation and coalescence phenomena in the cathodic Cu via during the early stage electromigration. Cu consumption due to the surface diffusion mechanism also occurred on the sidewall of the Cu via. Grain rotation within the Cu interconnect as a result of the electromigration-induced toque was also observed. The considerable mass loss in the Cu via upon electromigration caused a near-collapse microstructure of the Cu interconnect, leading to a potential reliability concern. Electromigration also induced the formation of Cu hillocks on the anodic Cu line, revealing a typical polarity effect. The Cu hillocks were derived from the predominant consumption of the Cu tall pillar rather than the Cu via or the Cu RDL due to the critical mass transport. The voids formed within the Cu tall pillar mostly appeared with a triple junction grain boundary morphology for the Cu consumption, suggesting a grain-boundary-related Cu migration mechanism. The grain boundary diffusion phenomenon was proposed to be the predominant mechanism for explaining the electromigration-induced void and hillock formation in the novel Cu tall pillar/Cu via interconnect.
Nasopharyngeal carcinoma (NPC) is an aggressive malignancy with extremely skewed ethnic and geographic distributions. Increasing evidence indicates that targeting the tumor microenvironment (TME) ...represents a promising therapeutic approach in NPC, highlighting an urgent need to deepen the understanding of the complex NPC TME. Here, we generated single-cell transcriptome profiles for 7581 malignant cells and 40,285 immune cells from fifteen primary NPC tumors and one normal sample. We revealed malignant signatures capturing intratumoral transcriptional heterogeneity and predicting aggressiveness of malignant cells. Diverse immune cell subtypes were identified, including novel subtypes such as CLEC9A
dendritic cells (DCs). We further revealed transcriptional regulators underlying immune cell diversity, and cell-cell interaction analyses highlighted promising immunotherapeutic targets in NPC. Moreover, we established the immune subtype-specific signatures, and demonstrated that the signatures of macrophages, plasmacytoid dendritic cells (pDCs), CLEC9A
DCs, natural killer (NK) cells, and plasma cells were significantly associated with improved survival outcomes in NPC. Taken together, our findings represent a unique resource providing in-depth insights into the cellular heterogeneity of NPC TME and highlight potential biomarkers for anticancer treatment and risk stratification, laying a new foundation for precision therapies in NPC.
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