The origin of the near-infrared photoluminescence (PL) from thiolate-protected gold nanoclusters (Au NCs, <2 nm) has long been controversial, and the exact mechanism for the enhancement of quantum yield (QY) in many works remains elusive. Meanwhile, based upon the sole steady-state PL analysis, it is still a major challenge for researchers to map out a definitive relationship between the atomic structure and the PL property and understand how the Au(0) kernel and Au(I)–S surface contribute to the PL of Au NCs. Herein, we provide a paradigm study to address the above critical issues. By using a correlated series of “mono-cuboctahedral kernel” Au NCs and combined analyses of steady-state, temperature-dependence, femtosecond transient absorption, and Stark spectroscopy measurements, we have explicitly mapped out a kernel-origin mechanism and clearly elucidate the surface–structure effect, which establishes a definitive atomic-level structure–emission relationship. A ∼100-fold enhancement of QY is realized via suppression of two effects: (i) the ultrafast kernel relaxation and (ii) the surface vibrations. The new insights into the PL origin, QY enhancement, wavelength tunability, and structure–property relationship constitute a major step toward the fundamental understanding and structural-tailoring-based modulation and enhancement of PL from Au NCs.
BACKGROUND: Gene expression can be posttranscriptionally regulated by a complex network of proteins. N1-methyladenosine (m1A) is a newly validated RNA modification. However, little is known about both its influence and biogenesis in tumor development. METHODS: This study analyzed TCGA data of patients with five kinds of gastrointestinal (GI) cancers. Using data from cBioPortal, molecular features of the nine known m1A-related enzymes in GI cancers were investigated. Using a variety of bioinformatics approach, the impact of m1A regulators on its downstream signaling pathway was studied. To further confirm this regulation, the effect of m1A writer ALKBH3 knockdown was studied using RNA-seq data from published database. RESULTS: Dysregulation and multiple types of genetic alteration of putative m1A-related enzymes in tumor samples were observed. The ErbB and mTOR pathways with ErbB2, mTOR, and AKT1S1 hub genes were identified as being regulated by m1A-related enzymes. The expression of both ErbB2 and AKT1S1 was decreased after m1A writer ALKBH3 knockdown. Furthermore, Gene Ontology analysis revealed that m1A downstream genes were associated with cell proliferation, and the results showed that m1A genes are reliably linked to mTOR. CONCLUSION: This study demonstrated for the first time the dysregulation of m1A regulators in GI cancer and its signaling pathways and will contribute to the understanding of RNA modification in cancer.
high photoexcitation intensity can lead to room-temperature magneto-photoluminescence and magneto-photocurrent with negative and positive signs, respectively, below the fi eld of 200 mT. Our results provide evidence that the charge recombination and dissociation are spin dependent at room temperature in OMHPs. Essentially, our results indicate that applying a magnetic fi eld can suppress the spin mixing between antiparallel and parallel spin states in electron-hole pairs and consequently decreases the antiparallel spin states but increases the parallel spin states. The change between different spin states in electron-hole pairs can eventually modify the exciton formation when the electron-hole pairs relax into excitons. Because of Pauli Exclusion Principle applied onto excitonic states, the singlet and triplet excitons can have high and low annihilation rates. As a result, decreasing the antiparallel spin states in electron-hole pairs by suppressing the spin mixing can weaken the singlet exciton formation, consequently leading to a decrease on photoluminescence toward the development of negative magneto-photoluminescence. On the contrary, decreasing the exciton formation can slow down the consumption on the electron-hole pairs. This can lead to more electron-hole pairs ready for charge dissociation to generate a photocurrent, generating a positive magneto-photocurrent. Clearly, the spin polarizations can be used as a new approach to control the charge recombination and dissociation in OMHPs. Furthermore, by using the observed magneto-photoluminescence and magneto-photocurrent, we investigate the dissociation effects in electron-hole pair states at different excitation intensities to further understand charge recombination and dissociation at different densities at device-operating condition. We fi nd that the critical bias required to completely quench the magneto-photocurrent and magneto-photoluminescence signals is increased with increasing photoexcitation intensity in OMHPs. This implies that, as the charge density increases with increasing the photoexcitation intensity, the formation of electron-hole pairs is enhanced, requiring a stronger fi eld to complete the charge dissociation toward generating photocurrent. Simultaneously, the line-shape on magneto-photocurrent and magnetophotoluminescence shows a narrowing phenomenon with increasing photoexcitation intensity. This indicates that the electron-hole pairs experience mutual inter-pair interactions and consequently changes the internal interactions within each electron-hole pairs. Clearly, our magneto-optical studies can provide critical understanding on controlling spin-dependent charge recombination and dissociation toward improving the photovoltaic actions in perovskite solar cells. Figure 1 a shows the magneto-photocurrents at different excitation intensities from the continuous wave (CW) laser beam of 532 nm in OMHP solar cells with the device architecture of ITO/PEDOT:PSS/CH 3 NH 3 PbI 3x Cl x /PC 71 BM/TiO x /Al. We Organometal halide perovskites (OM...
The figure of merit for refrigerators performing finite-time Carnot-like cycles between two reservoirs at temperature T(h) and T(c) (
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.