2435wileyonlinelibrary.com IntroductionQuantum dots (QDs), combined with unique optical, electrical properties and solution processed functional applications, have been studied intensively for decades. [ 1,2 ] Recently, Kovalenko and co-workers and Li and co-workers developed CsPbX 3 (X = Cl, Br, I) inorganic perovskite quantum dots (IPQDs), which exhibited ultrahigh photoluminescence (PL) quantum yields (QYs), lowthreshold lasing, and multicolor electroluminescence. However, the usual synthesis needs high temperature, inert gas protection, and localized injection operation, which are severely against applications. Moreover, the so unexpectedly high QYs are very confusing. Here, for the fi rst time, the IPQDs' roomtemperature (RT) synthesis, superior PL, underlying origins and potentials in lighting and displays are reported. The synthesis is designed according to supersaturated recrystallization (SR), which is operated at RT, within few seconds, free from inert gas and injection operation. Although formed at RT, IPQDs' PLs have QYs of 80%, 95%, 70%, and FWHMs of 35, 20, and 18 nm for red, green, and blue emissions. As to the origins, the observed 40 meV exciton binding energy, halogen self-passivation effect, and CsPbX 3 @X quantumwell band alignment are proposed to guarantee the excitons generation and high-rate radiative recombination at RT. Moreover, such superior optical merits endow them with promising potentials in lighting and displays, which are primarily demonstrated by the white light-emitting diodes with tunable color temperature and wide color gamut.
Graphene is a monolayer of tightly packed carbon atoms that possesses many interesting properties and has numerous exciting applications. In this work, we report the antibacterial activity of two waterdispersible graphene derivatives, graphene oxide (GO) and reduced graphene oxide (rGO) nanosheets. Such graphene-based nanomaterials can effectively inhibit the growth of E. coli bacteria while showing minimal cytotoxicity. We have also demonstrated that macroscopic freestanding GO and rGO paper can be conveniently fabricated from their suspension via simple vacuum filtration. Given the superior antibacterial effect of GO and the fact that GO can be mass-produced and easily processed to make freestanding and flexible paper with low cost, we expect this new carbon nanomaterial may find important environmental and clinical applications.
Metal-halide perovskites have rapidly emerged as one of the most promising materials of the 21st century, with many exciting properties and great potential for a broad range of applications, from photovoltaics to optoelectronics and photocatalysis. The ease with which metal-halide perovskites can be synthesized in the form of brightly luminescent colloidal nanocrystals, as well as their tunable and intriguing optical and electronic properties, has attracted researchers from different disciplines of science and technology. In the last few years, there has been a significant progress in the shape-controlled synthesis of perovskite nanocrystals and understanding of their properties and applications. In this comprehensive review, researchers having expertise in different fields (chemistry, physics, and device engineering) of metal-halide perovskite nanocrystals have joined together to provide a state of the art overview and future prospects of metal-halide perovskite nanocrystal research.
4929wileyonlinelibrary.com organic dyes and luminescent inorganic quantum dots. In 2010, Pan et al. successfully cut graphene sheets into blue luminescent graphene quantum dots via hydrothermal route, pushing the research of luminescent carbon materials to a climax. [ 10 ] Before that, much work has been done in the fi eld of bioimaging and optical sensing [11][12][13] while little research can be found in the optoelectronic devices or energy related applications. Since 2010, attempts on multiple applications, such as photovoltaic devices, [14][15][16][17][18] light emitting diodes, [19][20][21][22] photodetectors, [ 23,24 ] photocatalysis, [ 25 ] and lithium ion batteries, [ 26,27 ] were made. CDs and GQDs are gradually emerging in these areas and improving the performance of some kinds of devices with facile methods and low cost.Actually, GQDs can be recognized as one kind of CDs, which usually possess better crystallinity than its cousins. [ 28,29 ] In spite of the controversies on the origin of luminescence due to the excitation-dependent behavior, CDs and GQDs are expected to lead to low cost solar cells and organic LEDs (OLEDs) [ 16 ] and even can improve the performance of supercapacitors [ 27 ] and lithium ion batteries (LIBs) greatly. [ 26 ] Both of them have been synthesized with various methods, including top-down and bottom-up approaches. We are not going to talk about this because some reviews have concluded them. [30][31][32] In this Feature Article, we would like to update the latest researches about the applications of CDs and GQDs in optoelectronic devices and energy related devices, as shown in Figure 1 . Besides, there are no specifi c reviews that focus on the applications of CDs and GQDs in optoelectronic devices up to date though they have been studied for several years. In the next section, we will make a brief introduction of the microstructure and optical properties of these luminescent carbon materials. Section 3 covers the multiple applications of these interesting materials. We will focus on the application for optoelectronic and energy-related devices and make a brief introduction of other applications. In Section 4, we give a perspective for CDs and GQDs, including potential applications and possible development trend. In view of several excellent reviews focusing on different aspects of CDs and GQDs, such as their synthesis, biological applications, [ 30 ] photoluminescent properties and environmental applications, we hope this article will provide valuable insights for the current statues of CDs and GQDs research in optoelectronics and energy and stimulate new ideas and further research on their potential applications. Carbon and Graphene Quantum Dots for Optoelectronic and Energy
Printed flexible photodetectors based on 2D inorganic perovskites with atomic thickness show excellent photosensing with fast rise and decay response times. As-synthesized nanosheets can easily be dispersed in various solvents, leading to large-area, crack-free, low-roughness, flexible films after printing. This study demonstrates that all-inorganic perovskite CsPbX3 nanosheets as a new class of 2D semiconductors have huge potential for flexible optoelectronic applications.
Abstract. Twitter as a new form of social media can potentially contain much useful information, but content analysis on Twitter has not been well studied. In particular, it is not clear whether as an information source Twitter can be simply regarded as a faster news feed that covers mostly the same information as traditional news media. In This paper we empirically compare the content of Twitter with a traditional news medium, New York Times, using unsupervised topic modeling. We use a Twitter-LDA model to discover topics from a representative sample of the entire Twitter. We then use text mining techniques to compare these Twitter topics with topics from New York Times, taking into consideration topic categories and types. We also study the relation between the proportions of opinionated tweets and retweets and topic categories and types. Our comparisons show interesting and useful findings for downstream IR or DM applications.
The recent success of organometallic halide perovskites (OHPs) in photovoltaic devices has triggered lots of corresponding research and many perovskite analogues have been developed to look for devices with comparable performance but better stability. Upon the preparation of all inorganic halide perovskite nanocrystals (IHP NCs), research activities have soared due to their better stability, ultrahigh photoluminescence quantum yield (PL QY), and composition dependent luminescence covering the whole visible region with narrow line-width. They are expected to be promising materials for next generation lighting and display, and many other applications. Within two years, a lot of interesting results have been observed. Here, the synthesis of IHPs is reviewed, and their progresses in optoelectronic devices and optical applications, such as light-emitting diodes (LEDs), photodetectors (PDs), solar cells (SCs), and lasing, is presented. Information and recent understanding of their crystal structures and morphology modulations are addressed. Finally, a brief outlook is given, highlighting the presently main problems and their possible solutions and future development directions.
Tumour necrosis factor-alpha (TNF-alpha) is a proinflammatory mediator that exerts its biological functions by binding two TNF receptors (TNF-RI and TNF-RII), which initiate biological responses by interacting with adaptor and signalling proteins. Among the signalling components that associate with TNF receptors are members of the TNF-R-associated factor (TRAF) family. TRAF2 is required for TNF-alpha-mediated activation of c-Jun N-terminal kinase (JNK), contributes to activation of NF-kappaB, and mediates anti-apoptotic signals,. TNF-RI and TNF-RII signalling complexes also contain the anti-apoptotic ('inhibitor of apoptosis') molecules c-IAP1 and c-IAP2 (refs 5, 6), which also have RING domain-dependent ubiquitin protein ligase (E3) activity. The function of IAPs in TNF-R signalling is unknown. Here we show that binding of TNF-alpha to TNF-RII induces ubiquitination and proteasomal degradation of TRAF2. Although c-IAP1 bound TRAF2 and TRAF1 in vitro, it ubiquitinated only TRAF2. Expression of wild-type c-IAP1, but not an E3-defective mutant, resulted in TRAF2 ubiquitination and degradation. Moreover, E3-defective c-IAP1 prevented TNF-alpha-induced TRAF2 degradation and inhibited apoptosis. These findings identify a physiologic role for c-IAP1 and define a mechanism by which TNF-RII-regulated ubiquitin protein ligase activity can potentiate TNF-induced apoptosis.
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