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Quantum dot

B Karimi, B Ramezanzadeh
The reinforcement effect of graphene oxide nanosheets on the mechanical properties of an epoxy coating has been extensively studied. However, the effect of graphene oxide quantum dot (GOQD) as a new unique carbon based nanomaterial (with lateral dimension of 5-6nm and thickness of one carbon atom) on the mechanical properties of epoxy coating has not been reported and compared with GO yet. So this study aims at fabrication of a high-performance polymer composite with unique mechanical properties using GOQD nanosheets...
January 5, 2017: Journal of Colloid and Interface Science
Seyede Sara Khalili, Hossein Dehghani, Malihe Afrooz
This study reports the enhanced catalytic ability of metal ions-doped CoS and CoS/carbon allotrope counter electrodes (CEs) (synthesized using a successive ionic layer adsorption and reaction (SILAR) method) to improve the power conversion efficiency (η) in quantum dot-sensitized solar cells (QDSSCs). Firstly, doping effects of different metal ions (Mg(2+), Ca(2+), Sr(2+) and Ba(2+)) in the CoS CE on the QDSSCs performance have been investigated. Overall, among the different metal doped CoS CEs, the best energy conversion efficiency of 2...
January 5, 2017: Journal of Colloid and Interface Science
Mojtaba Shamsipur, Vahid Nasirian, Kamran Mansouri, Ali Barati, Asad Veisi-Raygani, Soheila Kashanian
A very sensitive and convenient nanobiosensor based on fluorescence resonance energy transfer (FRET) was developed for the detection of a 22-mer oligonucleotides sequence in Human Papillomavirus 18 virus (HPV18) gene. For this purpose, water-soluble CdTe quantum dots (QDs) were synthesized and, subsequently, amino-modified 11-mer oligonucleotide as one of the two necessary probes was attached to QDs surface to form functional QDs-DNA conjugates. Right after addition of the QDs-DNA and a second Cyanine5 (Cy5)-labeled 11-mer oligonucleotide probe to the DNA target solution, the sandwiched hybrids were formed...
January 3, 2017: Journal of Pharmaceutical and Biomedical Analysis
Alan Y Liu, Jon Peters, Xue Huang, Daehwan Jung, Justin Norman, Minjoo L Lee, Arthur C Gossard, John E Bowers
We demonstrate the first electrically pumped continuous-wave (CW) III-V semiconductor lasers epitaxially grown on on-axis (001) silicon substrates without offcut or germanium layers, using InAs/GaAs quantum dots as the active region and an intermediate GaP buffer between the silicon and device layers. Broad-area lasers with uncoated facets achieve room-temperature lasing with threshold current densities around 860  A/cm<sup>2</sup> and 110 mW of single-facet output power for the same device...
January 15, 2017: Optics Letters
Alessandro Crippa, Romain Maurand, Dharmraj Kotekar-Patil, Andrea Corna, Heorhii Bohuslavskyi, Alexei O Orlov, Patrick Fay, Romain Laviéville, Sylvain Barraud, Maud Vinet, Marc Sanquer, Silvano De Franceschi, Xavier Jehl
We report on dual-gate reflectometry in a metal-oxide-semiconductor double-gate silicon transistor operating at low temperature as a double quantum dot device. The reflectometry setup consists of two radio frequency resonators respectively connected to the two gate electrodes. By simultaneously measuring their dispersive responses, we obtain the complete charge stability diagram of the device. Electron transitions between the two quantum dots and between each quantum dot and either the source or the drain contact are detected through phase shifts in the reflected radio frequency signals...
January 12, 2017: Nano Letters
Mahdi Hesari, Zhifeng Ding
In most cases of semiconductor quantum dot nanocrystals, the inherent optical and electrochemical properties of these interesting nanomaterials do not translate into expected efficient electrochemiluminescence or electrogenerated chemiluminescence (ECL) because of the surface-state induction effect. Thus, their low ECL efficiencies, while very interesting to explore, limit their applications. As their electrochemistry is not well-defined, insight into their ECL mechanistic details is also limited. Alternatively, gold nanoclusters possess monodispersed sizes with atomic precision, low and well defined HOMO-LUMO energy gaps, and stable optical and electrochemical properties that make them suitable for potential ECL applications...
January 12, 2017: Accounts of Chemical Research
Shuang Jiao, Jun Du, Zhonglin Du, Donghui Long, Wuyou Jiang, Zhenxiao Pan, Yan Li, Xinhua Zhong
The exploration of catalyst materials for counter electrode (CE) in quantum dot sensitized solar cells (QDSCs) that have both high electrocatalytic activity and low charge transfer resistance is always significant yet challenging. In this work, we report the incorporation of nitrogen heteroatoms into carbon lattices leading to nitrogen doped mesoporous carbon (N-MC) materials with superior catalytic activity when used as CE in Zn-Cu-In-Se QDSCs. A series of N-MC materials with different nitrogen contents were synthesized by colloidal silica nanocasting method...
January 11, 2017: Journal of Physical Chemistry Letters
Xing Zhou, Xiangjun Zhang, Songling Han, Yin Dou, Mengyu Liu, Lin Zhang, Jia Wei Guo, Qing Shi, Genghao Gong, Ruibing Wang, Jiang Hu, Xiaohui Li, Jianxiang Zhang
Targeting of nanoparticles to distant diseased sites after oral delivery remains highly challenging, due to the existence of many biological barriers in the gastrointestinal tract. Here we report targeted oral delivery of diverse nanoparticles in multiple disease models, via a 'Trojan horse' strategy based on a bioinspired yeast capsule (YC). Diverse charged nanoprobes including quantum dots (QDs), iron oxide nanoparticles (IONPs), and assembled organic fluorescent nanoparticles can be effectively loaded into YC through electrostatic force-driven spontaneous deposition, resulting in different diagnostic YC assemblies...
January 11, 2017: Nano Letters
Ana Maria Calle, Monica Pacheco, George B Martins, Victor Apel, Gustavo Lara, Pedro Orellana
In the present work, we investigate the electronic transport through a T-shape double quantum dot system coupled to two normal leads and to one superconducting lead. We explore the interplay between Kondo and Andreev states due to proximity effects. We find that Kondo resonance is modified by the Andreev bound states, which manifest through Fano antiresonances in the local density of states of the embedded quantum dot and normal transmission. This means that there is a correlation between Andreev bound states and Fano resonances that is robust under the influence of high electronic correlation...
January 11, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Yuqing Zhang, Yuanyuan Qiu, Li Lin, Hongchen Gu, Zeyu Xiao, Jian Ye
Surface enhanced Raman scattering (SERS) tags can be utilized as optical labeling nanoprobes similar to fluorescent dyes and quantum dots for bioimaging with additional advantages of the fingerprint vibrational signal as a unique optical code and the ultra-narrow linewidth for multiplexing. However, the development of SERS imaging technique is much less well-established compared to fluorescence imaging mainly due to the speed limitation. An effective strategy to improve the SERS imaging speed and simultaneously maintain the photostability of SERS tags has been never reported to the best of our knowledge...
January 11, 2017: ACS Applied Materials & Interfaces
Eduard Carbonell-Sanromà, Pedro Brandimarte, Richard Balog, Martina Corso, Shigeki Kawai, Aran Garcia-Lekue, Shohei Saito, Shigehiro Yamaguchi, Ernst Meyer, Daniel Sánchez-Portal, Jose Ignacio Pascual
Bottom-up chemical reactions of selected molecular precursors on a gold surface can produce high quality graphene nanoribbons (GNRs). Here, we report on the formation of quantum dots embedded in an armchair GNR by substitutional inclusion of pairs of boron atoms into the GNR backbone. The boron inclusion is achieved through the addition of a small amount of boron substituted precursors during the formation of pristine GNRs. In the pristine region between two boron pairs, the nanoribbons show a discretization of their valence band into confined modes compatible with a Fabry-Perot resonator...
January 11, 2017: Nano Letters
Haijie Han, Daniel Valdeperez, Qiao Jin, Bin Yang, Zuhong Li, Yulian Wu, Beatriz Pelaz, Wolfgang J J Parak, Jian Ji
Dual enzymatic reactions were introduced to fabricate programmed gemcitabine (GEM) nanovectors for targeted pancreatic cancer therapy. Dual-enzyme sensitive GEM nanovectors were prepared by conjugation of matrix metalloproteinase-9 (MMP-9) detachable poly(ethylene glycol) (PEG), cathepsin B cleavable GEM, and targeting ligand CycloRGD to CdSe/ZnS quantum dots (QDs). The GEM nanovectors decorated with PEG corona could avoid nonspecific interactions and exhibit prolonged blood circulation time. After GEM nanovectors were accumulated in tumor tissue by the enhanced permeability and retention (EPR) effect, the PEG corona can be removed by overexpressed MMP-9 in tumor tissue and RGD would be exposed, which was capable of facilitating cellular internalization...
January 10, 2017: ACS Nano
Shuankui Li, Tianju Fan, Xuerui Liu, Fusheng Liu, Hong Meng, Yidong Liu, Feng Pan
Novel Bi2Te3/Graphene quantum dot (Bi2Te3/GQDs) hybrid nanosheets with a unique structure that GQDs homogeneously embedded in the Bi2Te3 nanosheet matrix have been synthesized by a simple solution-based synthetic strategy. A significantly reduced thermal conductivity and enhanced powder factor are observed in the pellet composed of Bi2Te3/GQDs nanosheets, which is ascribed to the optimized thermoelectric transport properties of the oxygen-containing Bi2Te3/GQDs interface. Furthermore, by varying the size of GQDs, the thermoelectric performance of Bi2Te3/GQDs hybrid nanostructures could be further enhanced, which could be attributed to the optimization of the density and dispersion manner of GQDs in the Bi2Te3 matrix...
January 10, 2017: ACS Applied Materials & Interfaces
Chun-Ting Li, Ryan Yeh-Yung Lin, Jiann T Lin
Aqueous dye-sensitized solar cells (DSSCs) are attractive due to sustainability and safety of using water as the solvent of the redox mediators, and possible applications of photoelectrochemical water splitting. However, higher tendency of dye-leaching by water and lower wettability of dye molecules are two major obstacles need to be tackled for future applications of aqueous DSSCs. Sensitizers designed for aqueous DSSCs are discussed based on their functions, such as modification of the molecular skeleton and the anchoring group for better stability against dye-leaching by water, and incorporation of hydrophilic entity in the dye molecule or addition of surfactant to the system to increase wettability of the dye for more facile dye regeneration...
January 10, 2017: Chemistry, An Asian Journal
Aparajita Das, Melepurath Deepa, Partha Ghosal
Lead-sulfide-selenide (PbSSe) quantum dots (QDs) and gold-copper (AuCu) alloy nanoparticles (NPs) are incorporated in a cadmium sulfide (CdS)/titanium oxide (TiO2) photoanode for the first time for enhanced conversion of solar energy to electricity. PbSSe QDs with a band gap of 1.02 eV, extend the light harvesting range of the photoanode from visible to the near infrared region. The conduction band (CB) edge of PbSSe QDs is wedged between the CBs of TiO2 and CdS; this additional level coupled with a good electrical conductivity of the dots facilitate charge transport and collection, for a high power conversion efficiency (PCE) of 4...
January 10, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Ali Newaz Bahar, Mohammad Maksudur Rahman, Nur Mohammad Nahid, Md Kamrul Hassan
This paper presents an energy dissipation dataset of different reversible logic gates in quantum-dot cellular automata. The proposed circuits have been designed and verified using QCADesigner simulator. Besides, the energy dissipation has been calculated under three different tunneling energy level at temperature T=2 K. For estimating the energy dissipation of proposed gates; QCAPro tool has been employed.
February 2017: Data in Brief
Ryan W Crisp, Gregory F Pach, J Matthew Kurley, Ryan M France, Matthew O Reese, Sanjini U Nanayakkara, Bradley A MacLeod, Dmitri V Talapin, Matthew C Beard, Joseph M Luther
We developed a monolithic CdTe/PbS tandem solar cell architecture where both the CdTe and PbS absorber layers are solution-processed from nanocrystal inks. Due to their tunable nature, PbS quantum dots (QDs), with a controllable bandgap between 0.4 and ~1.6 eV, are a promising candidate for a bottom absorber layer in tandem photovoltaics. In the detailed balance limit, the ideal configuration of a CdTe (Eg = 1.5 eV)/PbS tandem structure assumes infinite thickness of the absorber layers and requires the PbS bandgap to be 0...
January 10, 2017: Nano Letters
Govind Sharan Gupta, Ashutosh Kumar, Violet Aileen Senapati, Alok Kumar Pandey, Rishi Shanker, Alok Dhawan
The increasing applications of engineered nanomaterials (ENMs) in consumer products warrant a careful evaluation of their trophic transfer and consequent ecological impact. In the present study, a laboratory scale aquatic microbial food chain was established using bacteria (Escherichia coli) as a prey and ciliated protozoan (Paramecium caudatum) as a predator organism to determine the impact of cadmium telluride quantum dots (CdTe QDs). We observed that 29% of bacterivory potential of Paramecium was lost, including a ~12 h of delay in doubling time on exposure to 25 mg/L of CdTe QD (~4 nm) as compared to control...
January 9, 2017: Environmental Science & Technology
Xudong Yang, Yang Wang, Xiran Shen, Chunyan Su, Jinghua Yang, Mingjun Piao, Fei Jia, Guanghui Gao, Long Zhang, Quan Lin
Photoluminescent carbon dots (C-dots), as new members of the quantum sized carbon analogues have attracted significant attention due to their unique size, less toxicity, good compatibility and relatively easy surface modification. In this work, we report a simple, low-cost and one-step hydrothermal carbonization approach to synthesize the positively charged C-dots using PEI and FA. From the photoluminescence (PL) measurements, the as-prepared C-dots exhibit good stability and intense PL with the high quantum yield (QY) at Ca...
December 24, 2016: Journal of Colloid and Interface Science
Qingqing Li, Baoliang Chen, Baoshan Xing
The cooperative effects of pH and electrolytes on the aggregation of GQDs and the aggregate morphologies are characterized. Because GQDs have an average size of 9 nm with abundant O-functionalized edges, their suspension was very stable even in a high electrolyte concentration and low pH solution. Divalent cations (Mg2+ and Ca2+) exceled at aggregating the GQD nanoplates, while monovalent cations (Na+ and K+) did not disturb the stability. For Na+ and K+, positive linear correlations were observed between the critical coagulation concentration (CCC) and pH levels...
January 9, 2017: Environmental Science & Technology
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