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Quantum dot

Li-Juan Zhang, Li Xia, Shu-Lin Liu, En-Ze Sun, Qiu-Mei Wu, Li Wen, Zhi-Ling Zhang, Dai-Wen Pang
When infecting host cells, influenza virus must move on microfilaments (MFs) at the cell periphery and then move along microtubules (MTs) through the cytosol to reach the perinuclear region for genome release. But how viruses switch from the actin roadway to the microtubule highway remains obscure. To settle this issue, we systematically dissected the role of related motor proteins in the transport of influenza virus between cytoskeletal filaments in situ and in real-time using quantum dot (QD)-based single-virus tracking (SVT) and multicolor imaging...
December 12, 2017: ACS Nano
Jiaheng Sun, Qi Xin, Yang Yang, Hameed Shah, Hongqian Cao, Yanfei Qi, Jian Ru Gong, Junbai Li
A novel material with a large two-photon absorption cross-section was conjugated with a typical photosensitizer for inducing a FRET process. The photosensitizer can be excited by a one-/two-photon laser and then induced photo-toxicity in vitro and in vivo. The system presents great potential for improving treatment depth and the precision of traditional photodynamic therapy.
December 12, 2017: Chemical Communications: Chem Comm
Yan Liu, Yiqiang Qiao, Dan Luo, Min Yu, Ting Zhang, Xuanping Cao, Yanheng Zhou
A broad range of carbon sources have been used to fabricate varieties of carbon quantum dots (CQDs). However, majority of these studies concern on the influence of primary structures and chemical compositions of precursors on the CQDs; it is still unclear that whether the superstructures of carbon sources have effects on the physiochemical properties of the synthetic CQDs. In this work, the concept of molecular assembly is first introduced into design of a new carbon source. Compared with the tropocollagen molecules, the hierarchically assembled collagen scaffolds, as a new carbon source, immobilizes functional groups of the precursors through hydrogen bonds, electrostatic attraction and hydrophobic forces...
December 12, 2017: Chemistry: a European Journal
Jialin Tang, Yousong Liu, Yingjie Hu, Guoqing Lv, Chengtao Yang, Guangcheng Yang
A facile method of calcination was developed to in situ synthesize nanohybrids of Ti3+ self-doped TiO2/graphene quantum dot nanosheets (Ti3+-TiO2/GQDs NSs). Ti3+ sites were formed on the surface of TiO2 nanosheets through carbothermal reduction reaction by GQDs using citric acid as carbon source. Such heterojunctions exhibited enhanced visible-light absorption properties, large photocurrent current density and low recombination of photo-induced carriers. The methylene blue (MB) and rhodamine B (RhB) photodegradation result demonstrated higher visible-light photocatalysis performance than that of original TiO2...
December 12, 2017: Chemistry: a European Journal
Rafael Quintero-Bermudez, Randy P Sabatini, Marc Lejay, Oleksandr Voznyy, Edward H Sargent
Colloidal quantum dots (CQDs) enable low-cost, high-performance optoelectronic devices including photovoltaics, photodetectors, LEDs and lasers. Continuous-wave lasing in the near-infrared remains to be realized based on such materials; yet a solution-processed NIR laser would be of use in communications and interconnects. In infrared quantum dots, long-lived gain is hampered by a high rate of Auger recombination. Here we report the use of perovskite shells, grown on cores of IR-emitting PbS CQDs, and we reduce thereby the rate of Auger recombination by up to one order of magnitude...
December 11, 2017: ACS Nano
Akhilesh Babu Ganganboina, Ankan Dutta Chowdhury, Ruey-An Doong
The development of fast-response sensing technique for detection of cysteine can provide an analytical platform for pre-screening of disease. Herein, we have developed a fluorescence turn off-on fluorescence sensing platform by combining nitrogen-doped graphene quantum dots (N-GQD) with V2O5 nanosheets for the sensitive and selective detection of cysteine in human serum samples. V2O5 nanosheets with 2 - 4 layers are successfully synthesized via a simple and scalable liquid exfoliation method and then deposited with 2 - 8 nm of N-GQDs as the fluorescence turn off-on nanoprobe for effective detection of cysteine in human serum samples...
December 11, 2017: ACS Applied Materials & Interfaces
Hyung-Jun Song, Byeong Guk Jeong, Jaehoon Lim, Doh C Lee, Wan Ki Bae, Victor I Klimov
Luminescent solar concentrators (LSCs) can serve as large-area sunlight collectors for photovoltaic devices. An important LSC characteristic is a concentration factor (C), which is defined as the ratio of the output and the input photon flux densities. This parameter can be also thought of as an effective enlargement factor of a solar cell active area. Based on thermodynamic considerations, the C-factor can reach extremely high values that exceed those accessible with traditional concentrating optics. In reality, however, the best reported values of C are around 30...
December 11, 2017: Nano Letters
Maria Laura Pati, Elisabetta Fanizza, Sonja Hager, Diana Groza, Petra Heffeter, Amelita Grazia Laurenza, Valentino Laquintana, Maria Lucia Curri, Nicoletta Depalo, Carmen Abate, Nunzio Denora
The increasing importance of sigma-2 receptor as target for the diagnosis and therapy of tumours paves the way for the development of innovative optically traceable fluorescent probes as tumour cell contrast and therapeutic agents. Here, a novel hybrid organic-inorganic nanostructure is developed by combining the superior fluorescent properties of inorganic quantum dots (QDs), coated with a hydrophilic silica shell (QD@SiO2 NPs), the versatility of the silica shell and the high selectivity for sigma-2 receptors of the two synthetic ligands, namely the 6-[(6-aminohexyl)oxy]-2-(3-(6,7-dimethoxy-3,4-dihydroisoquinolin-2(1H)-yl)propyl)-3,4-dihydroisoquinolin-1(2H)-one (MLP66) and 6-[1-[3-(4-cyclohexylpiperazin-1-yl)propyl]-1,2,3,4-tetrahydronaphthalen-5-yloxy]hexylamine (TA6)...
December 11, 2017: Molecular Pharmaceutics
A A Galyean, M R Behr, K J Cash
Nanosensors present a biological monitoring method that is biocompatible, reversible, and nano-scale, and they offer many advantages over traditional organic indicators. Typical ionophore-based nanosensors incorporate nile-blue derivative pH indicators but suffer from photobleaching while quantum dot alternatives pose a potential toxicity risk. In order to address this challenge, sodium selective nanosensors containing carbon dots and a pH-sensitive quencher molecule were developed based on an ion-exchange theory and a decoupled recognition element from the pH indicator...
December 11, 2017: Analyst
Liang Luo, Ting Song, Haoqiang Wang, Qunhui Yuan, Shenghai Zhou
Inspired by low toxicity and good biocompatibility of biomass derived quantum dot (QD), we herein developed a cytosine derived quantum dot, namely cyt-dot, via a one-step hydrothermal synthesis. The as-prepared cyt-dot emits blue fluorescence (FL) containing abundant oxygen (20.6at.%) and nitrogen (24.1at.%) contents. The cyt-dot based sensing platform shows exclusive selectivity for Hg(II) while being insensitive towards Fe(III) and Ag(I), which are important interference that usually cannot be ruled out. The detection limit for Hg(II) is of 11nM, which is very close to the guideline value of 10nM allowed by the U...
November 22, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Jana Ryckaert, António Correia, Mickael D Tessier, Dorian Dupont, Zeger Hens, Peter Hanselaer, Youri Meuret
Quantum dots can be used in white LEDs for lighting applications to fill the spectral gaps in the combined emission spectrum of the blue pumping LED and a broad band phosphor, in order to improve the source color rendering properties. Because quantum dots are low scattering materials, their use can also reduce the amount of backscattered light which can increase the overall efficiency of the white LED. The absorption spectrum and narrow emission spectrum of quantum dots can be easily tuned by altering their synthesis parameters...
November 27, 2017: Optics Express
Dongping Long, Yunfei Shang, Youyi Qiu, Bin Zhou, Peihui Yang
A novel single-cell analysis platform (SCA) was developed for the investigation of platelets adhesion to single human umbilical vein endothelial cell (HUVEC) via using the adhesion molecule (E-selectin) on the damaged HUVEC as the marker site, and integrating electrochemiluminescence (ECL) with the ultrasensitive Au@DL-ZnCQDs nanoprobes. The Au@DL-ZnCQDs nanocomposite, a kind of double layer zinc-coadsorbed carbon quantum dot (ZnCQDs) core-shell nanoprobe, was firstly constructed by using gold nanoparticles (AuNPs) as the core to load with ZnCQDs and then the citrate-modified silver nanoparticles (AgNPs) as the bridge to link AuNPs-ZnCQDs with ZnCQDs to form the core-shell with double layer ZnCQDs (DL-ZnCQDs) nanoprobe, revealed a 10-fold signal amplification...
November 22, 2017: Biosensors & Bioelectronics
X Mi, Csaba G Péterfalvi, Guido Burkard, J R Petta
We study an accumulation mode Si/SiGe double quantum dot (DQD) containing a single electron that is dipole coupled to microwave photons in a superconducting cavity. Measurements of the cavity transmission reveal dispersive features due to the DQD valley states in Si. The occupation of the valley states can be increased by raising the temperature or applying a finite source-drain bias across the DQD, resulting in an increased signal. Using the cavity input-output theory and a four-level model of the DQD, it is possible to efficiently extract valley splittings and the inter- and intravalley tunnel couplings...
October 27, 2017: Physical Review Letters
A Hofmann, V F Maisi, T Krähenmann, C Reichl, W Wegscheider, K Ensslin, T Ihn
The spin-flip tunneling rates are measured in GaAs-based double quantum dots by time-resolved charge detection. Such processes occur in the Pauli spin blockade regime with two electrons occupying the double quantum dot. Ways are presented for tuning the spin-flip tunneling rate, which on the one hand gives access to measuring the Rashba and Dresselhaus spin-orbit coefficients. On the other hand, they make it possible to turn on and off the effect of spin-orbit interaction with a high on/off ratio. The tuning is accomplished by choosing the alignment of the tunneling direction with respect to the crystallographic axes, as well as by choosing the orientation of the external magnetic field with respect to the spin-orbit magnetic field...
October 27, 2017: Physical Review Letters
Xue-Yang Song, Chao-Ming Jian, Leon Balents
Prominent systems like the high-T_{c} cuprates and heavy fermions display intriguing features going beyond the quasiparticle description. The Sachdev-Ye-Kitaev (SYK) model describes a (0+1)D quantum cluster with random all-to-all four-fermion interactions among N fermion modes which becomes exactly solvable as N→∞, exhibiting a zero-dimensional non-Fermi-liquid with emergent conformal symmetry and complete absence of quasiparticles. Here we study a lattice of complex-fermion SYK dots with random intersite quadratic hopping...
November 24, 2017: Physical Review Letters
Yahya Alavirad, David Clarke, Amit Nag, Jay D Sau
Parafermionic zero modes are a novel set of excitations displaying non-Abelian statistics somewhat richer than that of Majorana modes. These modes are predicted to occur when nearby fractional quantum Hall edge states are gapped by an interposed superconductor. Despite substantial experimental progress, we argue that the necessary crossed Andreev reflection in this arrangement is a challenging milestone to reach. We propose a superconducting quantum dot array structure on a fractional quantum Hall edge that can lead to parafermionic zero modes from coherent superconducting forward scattering on a quantum Hall edge...
November 24, 2017: Physical Review Letters
Sourav Maiti, Farazuddin Azlan, Pranav Anand, Yogesh Jadhav, Jayanta Dana, Santosh K Haram, Hirendra N Ghosh
In search of a viable way to enhance the power conversion efficiency (PCE) of quantum dot sensitized solar cells (QDSSC) we have designed a method by introducing a hole transporting layer (HTL) of p-type CuS through partial cation exchange process in post synthetic ligand assisted assembly of nanocrystals (NCs). High quality CdSe and CdSSe gradient alloy NCs were synthesized through colloidal method and the charge carrier dynamics was monitored through ultrafast transient absorption (TA) measurements. Notable increase in the short circuit current concomitant with the increase in open circuit voltage and fill factor lead to 45% increment in PCE for CdSe based solar cell upon formation of the CuS HTL...
December 8, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Fanqi Wu, Liang Chen, Anyi Zhang, Yi-Lun Hong, Nai-Yun Shih, Seong-Yong Cho, Gryphon A Drake, Tyler Fleetham, Sen Cong, Xuan Cao, Qingzhou Liu, Yihang Liu, Chi Xu, Yuqiang Ma, Moonsub Shim, Mark E Thompson, Wencai Ren, Hui-Ming Cheng, Chongwu Zhou
Printing technology has potential to offer a cost-effective and scalable way to fabricate electronic devices based on two-dimensional (2D) transition metal dichalcogenides (TMDCs). However, limited by the registration accuracy and resolution of printing, the previously reported printed TMDC field-effect transistors (FETs) have relatively long channel lengths (13-200 μm), thus suffering low current-driving capabilities (≤0.02 μA/μm). Here, we report a "flood-dike" self-aligned printing technique that allows the formation of source/drain metal contacts on TMDC materials with sub-micrometer channel lengths in a reliable way...
December 8, 2017: ACS Nano
Pranav Tiwari, Sakshi Agarwal, Sachchidanand Srivastava, Shilpee Jain
Thermal therapy combined with chemotherapy is one of the advanced and efficient methods to eradicate cancer. In this work, we fabricated magnetically actuated smart textured (MAST) fibrous systems and studied their candidacy for cancer treatment. The polycaprolactone-Fe3 O4 based MAST fibers were fabricated using electrospinning technique. These MAST fibrous systems contained carbogenic quantum dots as a tracking agent and doxorubicin hydrochloride anticancer drug. Additionally, as fabricated MAST fibrous systems were able to deliver anticancer drug and heat energy simultaneously to kill HeLa cells in a 10 min period in vitro...
January 2018: Journal of Biomedical Materials Research. Part B, Applied Biomaterials
D M Zajac, A J Sigillito, M Russ, F Borjans, J M Taylor, G Burkard, J R Petta
Single qubit rotations and two-qubit CNOT operations are crucial ingredients for universal quantum computing. Although high fidelity single qubit operations have been achieved using the electron spin degree of freedom, realizing a robust CNOT gate has been challenging owing to rapid nuclear spin dephasing and charge noise. We demonstrate an efficient resonantly driven CNOT gate for electron spins in silicon. Our platform achieves single-qubit rotations with fidelities >99%, as verified by randomized benchmarking...
December 7, 2017: Science
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