Search results for " quantum dots"
showing 10 items of 47 documents
Fast Regulation of GABAAR Diffusion Dynamics by Nogo-A Signaling.
2019
Summary: Precisely controlling the excitatory and inhibitory balance is crucial for the stability and information-processing ability of neuronal networks. However, the molecular mechanisms maintaining this balance during ongoing sensory experiences are largely unclear. We show that Nogo-A signaling reciprocally regulates excitatory and inhibitory transmission. Loss of function for Nogo-A signaling through S1PR2 rapidly increases GABAAR diffusion, thereby decreasing their number at synaptic sites and the amplitude of GABAergic mIPSCs at CA3 hippocampal neurons. This increase in GABAAR diffusion rate is correlated with an increase in Ca2+ influx and requires the calcineurin-mediated dephospho…
Blue luminescent amino-functionalized graphene quantum dots as a responsive material for potential detection of metal ions and malathion
2022
Large amounts of hazardous and toxic substances in the environment require non-toxic, cheap, easy, rapid, and sensitive methods for their detection. Blue luminescent graphene quantum dots (GQDs) were produced by electrochemical cleavage of graphite electrodes followed by gamma irradiation in the presence of ethylenediamine (EDA). Modified dots were able to detect metal ions (Co2+, Pd2+, Fe3+) due to photoluminescence quenching. The highest sensitivity was detected for the sample irradiated at a dose of 25 kGy. The limits of detection (LODs) were 1.79, 2.55, and 0.66 μmol L−1 for Co2+, Fe3+, and Pd2+, respectively. It was observed that GQDs irradiated at 200 kGy act as an ultra-sensitive tur…
Single-Exciton Amplified Spontaneous Emission in Thin Films of CsPbX3 (X = Br, I) Perovskite Nanocrystals
2019
CsPbX3 perovskite nanocrystals (PNCs) have emerged as an excellent material for stimulated emission purposes, with even more prospective applications than conventional colloidal quantum dots. However, a better understanding of the physical mechanisms responsible for amplified spontaneous emission (ASE) is required to achieve more ambitious targets (lasing under continuous wave optical or electrical excitation). Here, we establish the intrinsic mechanisms underlying ASE in PNCs of three different band gaps (CsPbBr3, CsPbBr1.5I1.5, and CsPbI3). Our characterization at cryogenic temperatures does not reveal any evidence of the biexciton mechanism in the formation of ASE. Instead, the measured …
Flow cytometry and spectral imaging multiphoton microscopy analysis of CD36 expression with quantum dots 605 of untreated and 7-ketocholesterol-treat…
2006
To evaluate CD36 expression with quantum dots 605 (QDs 605) on untreated and 7-ketocholesterol (7KC)-treated monocytic U937 cells by flow cytometry (FCM) and confocal and multiphoton laser scanning microscopy (CLSM).Cells were analyzed by CLSM, following flow cytometric quantification of CD36 expression and 7KC uptake. Image sequences were obtained by spectral analysis in monophoton and multiphoton CLSM and analyzed by the factor analysis of medical image sequences (FAMIS) algorithm to differentiate emission spectra. In CLSM analysis, cell deposits were screened in ultraviolet excitation modes to optimize the possibilities of QDs 605 and have the benefit of nuclei counterstaining by DAPI.FC…
Struktūra un fotofizikālie procesi 0D un 1D InGaN kompozītu materiālos
2014
Šajā disertācijā tiek aprakstīti strukturālās un fotofizikālās MOCVD izaudzēto GaN nanovadu (NV) un InGaN kvantu punktu (KP) īpašības. Abos gadījumos ir parādīts, ka ex-situ RHEED mērījumi ir iespējami un sniedz kvalitatīvu informāciju par struktūru. Kombinācijā ar citām metodēm, pirmkārt, ir parādīts, ka nemetāliskā katalizatora veicinātā GaN NV īpašības, kad sintezēts uz GaN (0001) virsmas, atšķiras no tradicionāli iegūtajiem. Šinī gadījumā katalizators lokalizējas pie nanovadu pamatnes nevis tā galā un augšanas virziens ir atšķirīgs no kristalogrāfiskās c-ass, rezultātā iegūstot semipolārās NV struktūras. Otrkārt, InGaN kvantu punktos ir konstatēt saspiesta kristāliskā režģa struktūra au…
Random population model to explain the recombination dynamics in single InAs/GaAs quantum dots under selective optical pumping
2011
18 páginas, 3 tablas, 9 figuras.-- et al.
Size dependent carrier thermal escape and transfer in bimodally distributed self assembled InAs/GaAs quantum dots
2012
We have investigated the temperature dependent recombination dynamics in two bimodally distributed InAs self assembled quantum dots samples. A rate equations model has been implemented to investigate the thermally activated carrier escape mechanism which changes from exciton-like to uncorrelated electron and hole pairs as the quantum dot size varies. For the smaller dots, we find a hot exciton thermal escape process. We evaluated the thermal transfer process between quantum dots by the quantum dot density and carrier escape properties of both samples. © 2012 American Institute of Physics.
Entanglement dynamics of two independent cavity-embedded quantum dots
2010
We investigate the dynamical behavior of entanglement in a system made by two solid-state emitters, as two quantum dots, embedded in two separated micro-cavities. In these solid-state systems, in addition to the coupling with the cavity mode, the emitter is coupled to a continuum of leaky modes providing additional losses and it is also subject to a phonon-induced pure dephasing mechanism. We model this physical configuration as a multipartite system composed by two independent parts each containing a qubit embedded in a single-mode cavity, exposed to cavity losses, spontaneous emission and pure dephasing. We study the time evolution of entanglement of this multipartite open system finally …
Enhanced nanoscopy of individual CsPbBr3 perovskite nanocrystals using dielectric sub-micrometric antennas
2020
We demonstrate an efficient, simple, and low-cost approach for enhanced nanoscopy in individual green emitting perovskite (CsPbBr3) nanocrystals via TiO2 dielectric nanoantenna. The observed three- to five-fold emission enhancement is attributed to near-field effects and emission steering promoted by the coupling between the perovskite nanocrystals and the dielectric sub-micrometric antennas. The dark-field scattering configuration is then exploited for surface-enhanced absorption measurements, showing a large increase in detection sensitivity, leading to the detection of individual nanocrystals. Due to the broadband spectral response of the Mie sub-micrometric antennas, the method can be e…
Hyaluronic acid and its derivatives in drug delivery and imaging: Recent advances and challenges.
2015
Hyaluronic acid (HA) is a biodegradable, biocompatible, nontoxic, and non-immunogenic glycosaminoglycan used for various biomedical applications. The interaction of HA with the CD44 receptor, whose expression is elevated on the surface of many types of tumor cells, makes this polymer a promising candidate for intracellular delivery of imaging and anticancer agents exploiting a receptor-mediated active targeting strategy. Therefore, HA and its derivatives have been most investigated for the development of several carrier systems intended for cancer diagnosis and therapy. Nonetheless, different and important delivery applications of the polysaccharide have also been described, including gene …