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Red dot

Ruilin Xu, Chen Liao, Yanqing Xu, Chunfeng Zhang, Min Xiao, Lei Zhang, Changgui Lu, Yiping Cui, Jiayu Zhang
Mn(2+) ions were introduced as exciton couplers to enhance the quantum yield (QY) of type-II photoluminescence (PL) from CdS/ZnSe/ZnS quantum dots (QDs) with slow hot-exciton cooling and low radiative rate. Transient absorption spectroscopy verifies the faster bleach recovery and faster peak red-shifting at the charge-transfer state. And the transient PL peak of the QDs changes from blue-shifting to red-shifting due to Mn(2+) doping. The QY of type-II PL can be enhanced from ∼35% to ∼60% by Mn(2+) doping...
November 15, 2017: Nanoscale
Weijie He, Rijun Gui, Hui Jin, Benqian Wang, Xiangning Bu, Yongxin Fu
In this article, blue-emitting carbon dots (CDs) were prepared via hydrothermal treatment of sodium citrate and NH4HCO3, and then combined with 3-aminophenylboronic acid (APBA) to prepare APBA modified-CDs. APBA acted as the receptor of dopamine (DA). Using bovine serum albumin (BSA) as a stabilizer and N2H4·H2O as a reducing reagent, BSA-stabilized and red-emitting copper nanoclusters (CuNCs) were prepared. By carbodiimide-activated coupling, novel nanohybrids consisting of CDs and CuNCs were constructed and exhibited dual-emitting fluorescence (FL)...
February 1, 2018: Talanta
Katerina Hola, Mária Sudolská, Sergii Kalytchuk, Dana Nachtigallova, Andrey L Rogach, Michal Otyepka, Radek Zbořil
Carbon dots (CDs) are a stable and highly biocompatible fluorescent material offering great application potential in cell labeling, optical imaging, LED diodes, and optoelectronic technologies. Because their emission wavelengths provide the best tissue penetration, red-emitting CDs are of a particular interest for applications in biomedical technologies. Current synthetic strategies enabling red-shifted emission include increasing the CD particle size (sp2 domain) by a proper synthetic strategy and tuning the surface chemistry of CDs with suitable functional groups (e...
November 14, 2017: ACS Nano
Antonio Maffei, Alessandro Angrilli
Blink rate is a behavioral index highly correlated with frontostriatal dopaminergic activity. The present research was aimed at studying the modulation of spontaneous blink rate in function of the increasing attentional load induced by the Mackworth Clock Test. Since blinking interferes with sensory processing, we expected a decreasing blink rate with increasing attentional demand. Three tasks of 7-min each and different difficulties were administered: the Mackworth had a red dot moving in a circle with intervals varying from 500ms, 350ms to 200ms, corresponding to increasing task difficulty...
November 11, 2017: International Journal of Psychophysiology
Hyun Chul Park, Isnaeni, Suhyun Gong, Yong-Hoon Cho
Enhancing the fluorescence intensity of colloidal quantum dots (QDs) in case of color-conversion type QD light-emitting devices (LEDs) is very significant due to the large loss of QDs and their quantum yields during fabrication processes, such as patterning and spin-coating, and can therefore improve cost-effectiveness. Understanding the enhancement process is crucial for the design of metallic nanostructure substrates for enhancing the fluorescence of colloidal QDs. In this work, improved color conversion of colloidal green and red QDs coupled with aluminum (Al) and silver (Ag) nanodisk (ND) arrays designed by in-depth systematic finite-difference time domain simulations of excitation, spontaneous emission, and quantum efficiency enhancement is reported...
November 9, 2017: Small
Yijun Zhang, Rongrong Yuan, Meiling He, Guangcai Hu, Jutao Jiang, Tao Xu, Lei Zhou, Wei Chen, Weidong Xiang, Xiaojuan Liang
The first use of the combination of ammonium citrate (AC) and ethylenediamine tetraacetic acid (EDTA) as coordinating precursors for the synthesis of highly fluorescent (quantum yield = 67%) multicolour nitrogen-doped carbon dots (CDs) is reported. Under UV light, these CDs emitted outstanding luminescence in colours from dark blue to red. Interestingly, a single component white-light CD point with high fluorescence efficiency was obtained by surface control. Alterations of the photoluminescence (PL) emission of these full-colour CDs were tentatively proposed to benefit from surface functional groups, such as C[double bond, length as m-dash]O and C[double bond, length as m-dash]N...
November 8, 2017: Nanoscale
Victor Nadtochenko, Nikolay Denisov, Arseniy Aybush, Fedor Gostev, Ivan Shelaev, Andrey Titov, Stanislav Umanskiy, And Dmitry Cherepanov
The main goal of the present work is to study the coherent phonon in strongly confined CdSe quantum dots (QDs) under varied pump fluences. The main characteristics of coherent phonons (amplitude, frequency, phase, spectrogram) of CdSe QDs under the red-edge pump of the excitonic band [1S(e)-1S3/2(h)] are reported. We demonstrate for the first time that the amplitude of the coherent optical longitudinal-optical (LO) phonon at 6.16 THz excited in CdSe nanoparticles by a femtosecond unchirped pulse shows a non-monotone dependence on the pump fluence...
November 4, 2017: Nanomaterials
Jiasheng Li, Yong Tang, Zongtao Li, Xinrui Ding, Dong Yuan, Binhai Yu
CdSe/ZnS quantum-dot-converted elements (QDCEs) are good candidates for substituting rare-earth phosphor-converted elements (PCEs) in white light-emitting diodes (LEDs); however, studies on their scattering and absorption properties are scarce, suppressing further increment in the optical and thermal performance of quantum-dot-converted LEDs. Therefore, we introduce the finite-difference time-domain (FDTD) method to achieve the critical optical parameters of QDCEs when used in white LEDs; their scattering cross-section (coefficient), absorption cross-section (coefficient), and scattering phase distributions are presented and compared with those of traditional YAG phosphor-converted elements (PCEs) at varying particle size and concentration...
November 3, 2017: Materials
Guillaume Raffy, Robin Bofinger, Arnaud Tron, André Del Guerzo, Nathan D McClenaghan, Jean-Marc Vincent
An innovative photopatterning process is described that allows, in a single laser-promoted operation, the covalent attachment of a molecule on a surface (2D patterning - xy dimensions) and its photopolymerization to grow micro-/nanostructures with spatial control in a third z-dimension. The surface patterning process, based on nitrene reactivity, was harnessed using the highly fluorescent azide-substituted boron difluoride dipyrromethene (BODIPY) 1 that was prepared in a single synthetic step from the parent pentafluorophenyl BODIPY on reacting with NaN3...
November 9, 2017: Nanoscale
Moon Kee Choi, Jiwoong Yang, Dong Chan Kim, Zhaohe Dai, Junhee Kim, Hyojin Seung, Vinayak S Kale, Sae Jin Sung, Chong Rae Park, Nanshu Lu, Taeghwan Hyeon, Dae-Hyeong Kim
Displaying information on transparent screens offers new opportunities in next-generation electronics, such as augmented reality devices, smart surgical glasses, and smart windows. Outstanding luminance and transparency are essential for such "see-through" displays to show vivid images over clear background view. Here transparent quantum dot light-emitting diodes (Tr-QLEDs) are reported with high brightness (bottom: ≈43 000 cd m(-2) , top: ≈30 000 cd m(-2) , total: ≈73 000 cd m(-2) at 9 V), excellent transmittance (90% at 550 nm, 84% over visible range), and an ultrathin form factor (≈2...
October 25, 2017: Advanced Materials
Hongzhi Lu, Shuai Quan, Shoufang Xu
In this work, we developed a simple and sensitive ratiometric fluorescent assay for sensing trinitrotoluene (TNT) based on the inner filter effect (IFE) between gold nanoparticles (AuNPs) and ratiometric fluorescent nanoparticles (RFNs), which was designed by hybridizing green emissive carbon dots (CDs) and red emissive quantum dots (QDs) into a silica sphere as a fluorophore pair. AuNPs in their dispersion state can be a powerful absorber to quench CDs, while the aggregated AuNPs can quench QDs in the IFE-based fluorescent assays as a result of complementary overlap between the absorption spectrum of AuNPs and emission spectrum of RFNs...
October 25, 2017: Journal of Agricultural and Food Chemistry
Jing-Xing Wu, Bing Yan
A highly selective and sensitive ratiometric fluorescent probe for copper ions (Cu(2+)) in aqueous solution based on a blue zirconium metal-organic framework [UiO-66-(COOH)2] with red bandgap fluorescent carbon quantum dots (R-BF-CQDs) is developed. UiO-66-(COOH)2 displays broad ligand-centered (LC) emission and R-BF-CQDs shows red emission. Interestingly, the remaining -NH2 at the surface of the prepared R-BF-CQDs can coordinate Cu(2+) efficiently and produce a strong visible absorption, which overlaps the emission of UiO-66-(COOH)2...
November 7, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Ying Liu, Ding-Kun Ji, Lei Dong, Nicolas Galanos, Yi Zang, Jia Li, Sébastien Vidal, Xiao-Peng He
Supramolecular self-assembly between perylenediimide-based glycoclusters and a red-emitting fluorophore produces structurally uniform and stable glyco-dots amenable to targeted fluorogenic imaging of liver and triple-negative breast cancer cells.
October 19, 2017: Chemical Communications: Chem Comm
Feng Li, Lai You, Chao Nie, Qin Zhang, Xiao Jin, Haiyang Li, Xiaobing Gu, Yan Huang, Qinghua Li
Alloy core/shell CdxZn1-xS/ZnS quantum dots (QDs) are emerging as robust candidates for light-emitting diodes (LEDs), however the emission range of the current CdxZn1-xS/ZnS is quite limited, ranging from 390 to 470 nm. It still remains a challenging task to construct white LEDs based on current CdxZn1-xS/ZnS system. Here, a versatile ZnSe with a moderate band gap is introduced onto the Cd0.1Zn0.9S core. The ZnSe shell, on one hand, can passivate the core surface which leads to bright emissions. On the other hand, it is essential in extending the emission to red region so that the emission wavelengths of Cd0...
September 4, 2017: Optics Express
K Rae, C Foucher, B Guilhabert, M S Islim, L Yin, D Zhu, R A Oliver, D J Wallis, H Haas, N Laurand, M D Dawson
Red-, orange-, and green-emitting integrated optoelectronic sources are demonstrated by transfer printing blue InGaN µLEDs onto ultra-thin glass platforms functionally enhanced with II-VI colloidal quantum dots (CQDs). The forward optical power conversion efficiency of these heterogeneously integrated devices is, respectively, 9%, 15%, and 14% for a blue light absorption over 95%. The sources are demonstrated in an orthogonal frequency division multiplexed (OFDM) visible light communication link reaching respective data transmission rates of 46 Mbps, 44 Mbps and 61 Mbps...
August 7, 2017: Optics Express
Hui Ding, Ji-Shi Wei, Ning Zhong, Qing-Yu Gao, Huan-Ming Xiong
Carbon dots (CDs) are a new class of photoluminescent (PL), biocompatible, environment-friendly, and low-cost carbon nanomaterials. Synthesis of highly efficient red-emitting carbon dots (R-CDs) on a gram scale is a great challenge at present, which heavily restricts the wide applications of CDs in the bioimaging field. Herein, R-CDs with a high quantum yield (QY) of 53% are produced on a gram scale by heating a formamide solution of citric acid and ethylenediamine. The as-prepared R-CDs have an average size of 4...
October 26, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Chen Zou, Chun-Ying Huang, Erin M Sanehira, Joseph M Luther, Lih Y Lin
Recently, all-inorganic perovskites such as CsPbBr3 and CsPbI3, have emerged as promising materials for light-emitting applications. While encouraging performance has been demonstrated, the stability issue of the red-emitting CsPbI3 is still a major concern due to its small tolerance factor. Here we report a highly stable CsPbI3 quantum dot (QD) light-emitting diode (LED) with red emission fabricated using an improved purification approach. The device achieved decent external quantum efficiency (EQE) of 0.21% at a bias of 6 V and outstanding operational stability, with a L 70 lifetime (EL intensity decreases to 70% of starting value) of 16 h and 1...
October 17, 2017: Nanotechnology
Junyong Sun, Pinghua Ling, Feng Gao
The accurate and sensitive monitoring and imaging of mitochondrial pH in living cells play vital roles in chemical biology and biomedicine. Herein, we design a novel ratiometric fluorescent chemical probe for monitoring and imaging the pH of mitochondria in living cells based on congo-red (CR)-modified dual-emission semiconducting polymer dots (Pdots) via a competitive fluorescence resonance energy transfer (FRET) mechanism. The Pdots are synthesized by triphenylphosphonium (TPP)-modified polyoxyethylene nonylphenylether (CO-520), poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO), poly(9,9-dioctylfluorene)-co-(4,7-di-2-thienyl-2,1,3-benzothiadiazole) (PF-DBT5), and poly(styrene-co-maleic anhydride) (PSMA) via a nanoprecipitation method, and the prepared Pdots are further chemically linked with pH-sensitive, nonfluorescent CR to obtain the mitochondria-targeted pH fluorescent probes...
November 7, 2017: Analytical Chemistry
Donald K L Chan, Jimmy C Yu, Yecheng Li, Zhuofeng Hu
A simple approach to enhance the photocatalytic activity of red phosphorus (P) was developed. A mechanical ball milling method was applied to reduce the size of red P and to deposit graphene quantum dots onto red P. The product was characterized by scanning electron microscopy, transmission electron microscopy, contact angle measurements, zeta-potential measurements, X-ray diffraction and UV-vis absorption spectroscopy. The product exhibited high visible-light-driven photocatalytic performance in the photodegradation of rhodamine B...
October 2017: Journal of Environmental Sciences (China)
Diego Rosselli, James K Wetterer
Numerous researchers have observed a form of punctate corneal lesions causing leukomas (corneal opacities) in humans, domestic animals, and wild animals in different parts of the world. This condition has been reported under different names, including West Indian (or Caribbean) punctate keratopathy, West Indian dots, tropical punctate keratopathy, Rice's keratopathy, Florida keratopathy, and Florida spots. Many of these cases, appear to have a common cause, the stings of a small red ant, Wasmannia auropunctata (Hymenoptera: Formicidae), originally from the Neotropics, but spread to other parts of the world through human commerce...
November 7, 2017: Journal of Medical Entomology
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