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Ankit Jain, Oleksandr Voznyy, Marek Korkusinski, Pawel Hawrylak, Edward H Sargent
It has previously been found that Auger processes can lead to femtosec- ond carrier trapping in quantum dots, limiting their performance in opto- electronic applications that rely on radiative recombination. Here, using atomistic simulations, we investigate whether a shell can protect carriers from Auger-assisted trapping. For these studies we investigate CdSe/CdS core-shell quantum dots having total diameters reaching up to 10 nm. We find trapping lifetimes as fast as 1 ps for 2 nm shells, and we report that shells as thick as 6 nm are required to suppress trapping fully...
June 21, 2017: Journal of Physical Chemistry Letters
Liangwen Yan, Sijung Hu, Abdullah Alzahrani, Samah Alharbi, Panagiotis Blanos
Different skin pigments among various ethnic group people have an impact on spectrometric illumination on skin surface. To effectively capture photoplethysmographic (PPG) signals, a multi-wavelength opto-electronic patch sensor (OEPS) together with a schematic architecture of electronics were developed to overcome the drawback of present PPG sensor. To perform a better in vivo physiological measurement against skin pigments, optimal illuminations in OEPS, whose wavelength is compatible with a specific skin type, were optimized to capture a reliable physiological sign of heart rate (HR)...
June 21, 2017: Biosensors
Mehdi Shakourian-Fard, Hadiseh Heydari, Ganesh Kamath
Defect engineering could potentially allow for dramatic tuning of optoelectronic properties of two-dimensional materials. With the help of density functional theory (DFT) calculations, we present a systematic study of the DNA Nucleobases (NBs) adsorbed on hexagonal boron-nitride nanoflake (h-BNNF) and boron and nitrogen monovacancies. The presence of such VN and VB defects increases the binding strength of NBs by 9 kcal/mol and 34 kcal/mol, respectively (h-BNNF-VB> h-BNNF-VN> h-BNNF). A more negative electrostatic potential at the B vacancy-site makes h-BNNF-VB surface more reactive than h-BNNF-VN surface enabling H-bonding interactions with NBs...
June 20, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Vitor Brasiliense, Jan Clausmeyer, Alice L Dauphin, Jean-Marc Noël, Pascal Berto, Gilles Tessier, Wolfgang Schuhmann, Frederic Kanoufi
Single particle electrochemistry at a nanoelectrode is explored by dark-field optical microscopy. The analysis of the scattered light allows in situ dynamic monitoring of the electrodeposition of single cobalt nanoparticles down to a radius of 65 nm. Larger sub-micrometer particles are directly sized optically by edges super-localization and the scattered light contains complementary chemical information concerning the particle redox chemistry. This opto-electrochemical approach is used to derive mechanistic insights about electrocatalysis which are not accessible from single particle electrochemistry...
June 19, 2017: Angewandte Chemie
Adrian Podpirka, Woo-Kyung Lee, Jed I Ziegler, Todd H Brintlinger, Jonathan R Felts, Blake S Simpkins, Nabil D Bassim, Arnaldo R Laracuente, Paul E Sheehan, Laura B Ruppalt
The crystallization of amorphous germanium telluride (GeTe) thin films is controlled with nanoscale resolution using the heat from a thermal AFM probe. The dramatic differences between the amorphous and crystalline GeTe phases yield embedded nanoscale features with strong topographic, electronic, and optical contrast. The flexibility of scanning probe lithography enables the width and depth of the features, as well as the extent of their crystallization, to be controlled by varying probe temperature and write speed...
June 19, 2017: Nanoscale
Asma Bensghaïer, Stephanie Lau-Truong, Mahamadou Seydou, Aazdine Lamouri, Eric Leroy, Matej Micusik, Klaudia Forro, Mohamed Beji, Jean Pinson, Maria Omastova, Mohamed Mehdi Chehimi
Tetrafluoroborate salts of diazotized Azure A (AA-N2+), Neutral Red (NR-N2+) and Congo Red (CR-N2+) dyes were prepared and reacted with multiwalled carbon nanotubes (MWCNTs) at room temperature, in water without any reducing agent. The as-modified MWCNTs were examined by IRATR, Raman spectroscopy, XPS, TGA, TEM and cyclic voltammetry. The diazonium band located at 2350 cm-1 in the diazotized dye IR spectra vanished after attachment to the nanotubes whilst Raman D/G peak ratio slightly increased after dye covalent attachment at high initial diazonium/CNT mass ratio...
June 16, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Haigang Ma, Sihua Yang, Zhongwen Cheng, Da Xing
Recently, intensive research on photoacoustic (PA) imaging has been conducted to accelerate the development of dermoscopy of the human skin. In this Letter, we first developed a PA dermoscope equipped with a waterless coupling and impedance matching opto-sono probe to achieve quantitative, high-resolution, and high-contrast imaging of the human skin. Compared with the commonly used liquid-coupled PA probes, the human-skin-adapted probe can facilitate implementation in the clinical setting. The noninvasive imaging experiments of epidermal and dermal structures in volunteers have been carried out to demonstrate the high imaging quality that can be obtained by using such an opto-sono probe for a PA dermoscope...
June 15, 2017: Optics Letters
Robert W Arnold, Robin L Grendahl, R Kevin Winkle, Jack Jacob
Eight infants were closely monitored for retinopathy of prematurity (ROP) while in the neonatal intensive care unit (NICU); two required laser therapy. After discharge from the NICU, they had outpatient examination with dilated, scleral depressed ROP staging, and each had digital widefield retinal imaging (Optos, Dunfermline, United Kingdom) without lid speculum, or with lid speculum if not cooperative. Images were shared remotely using ROP-Check software (Glacier Medical Software, Anchorage, AK), from which ophthalmologists made clinical impressions...
June 1, 2017: Ophthalmic Surgery, Lasers & Imaging Retina
Guohua Wei, David A Czaplewski, Erik J Lenferink, Teodor K Stanev, Il Woong Jung, Nathaniel P Stern
Three-dimensional confinement allows semiconductor quantum dots to exhibit size-tunable electronic and optical properties that enable a wide range of opto-electronic applications from displays, solar cells and bio-medical imaging to single-electron devices. Additional modalities such as spin and valley properties in monolayer transition metal dichalcogenides provide further degrees of freedom requisite for information processing and spintronics. In nanostructures, however, spatial confinement can cause hybridization that inhibits the robustness of these emergent properties...
June 12, 2017: Scientific Reports
M Arifur Rahman, Julian Cheng, Zhidong Wang, Aaron T Ohta
Micromanipulation for applications in areas such as tissue engineering can require mesoscale structures to be assembled with microscale resolution. One method for achieving such manipulation is the parallel actuation of many microrobots in parallel. However, current microrobot systems lack the independent actuation of many entities in parallel. Here, the independent actuation of fifty opto-thermocapillary flow-addressed bubble (OFB) microrobots in parallel is demonstrated. Individual microrobots and groups of microrobots were moved along linear, circular, and arbitrary 2D trajectories...
June 12, 2017: Scientific Reports
Shahid Muhammad, Yuting Wang, Jun Yang, Tianjun Li, Yang Xing, Jing Cheng, Mengfei Zhang, Chunlei Wan, Wei Pan
Flexible and transparent electronics is the emerging future technology for the optoelectronics devices. Recently, it has attracted a considerable attention from the research community due to its prodigious commercial applications. Herein, we report highly flexible and transparent ultraviolet photosensors based on indium doped tin oxide nanobelts with enhanced photosensitivity and recovery speed at the same time, as compared to the pure SnO2 nanobelts. The opto-electronics properties of the nanobelts photosensors have been found in strong relation with indium doping concentration and the grain size of the nanobelts...
June 13, 2017: Nanotechnology
Nicholas S Colella, Joelle A Labastide, Benjamin P Cherniawski, Hilary B Thompson, Sarah R Marques, Lei Zhang, Özlem Usluer, James J Watkins, Alejandro L Briseno, Michael D Barnes
Supercritical fluids, exhibiting a combination of liquid-like solvation power and gas-like diffusivity, are a relatively unexplored medium for processing and crystallization of oligomer and polymeric semiconductors whose opto-electronic properties critically depend on the microstructure. Here we report oligomer crystallization from the polymer organic semiconductor, poly[2,5-bis(3-dodecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT) in supercritical hexane, yielding needle-like single crystals up to several microns in length...
June 12, 2017: Journal of Physical Chemistry Letters
Krishna C Balram, Marcelo I Davanço, B Robert Ilic, Ji-Hoon Kyhm, Jin Dong Song, Kartik Srinivasan
Acoustic wave devices provide a promising chip-scale platform for efficiently coupling radio frequency (RF) and optical fields. Here, we use an integrated piezo-optomechanical circuit platform that exploits both the piezoelectric and photoelastic coupling mechanisms to link 2.4 GHz RF waves to 194 THz (1550 nm) optical waves, through coupling to propagating and localized 2.4 GHz acoustic waves. We demonstrate acousto-optic modulation, resonant in both the optical and mechanical domains, in which waveforms encoded on the RF carrier are mapped to the optical field...
February 2017: Physical Review Applied
Abhilash Guduru, David Fleischman, Sunyoung Shin, Donglin Zeng, James B Baldwin, Odette M Houghton, Emil A Say
BACKGROUND: Establish accuracy and reproducibility of subjective grading in ultra-widefield fundus autofluorescence (FAF) imaging in patients with age-related macular degeneration (AMD), and determine if an association exists between peripheral FAF abnormalities and AMD. METHODS: This was a prospective, single-blinded case-control study. Patients were consecutively recruited for the study. Patients were excluded if there was a history of prior or active ocular pathology other than AMD or image quality was insufficient for analysis as determined by two independent graders...
2017: PloS One
Linhan Lin, Xiaolei Peng, Yuebing Zheng
We have developed a new optical technique - opto-thermoelectric printing - to print colloidal particles with reconfigurable patterns on substrates via light-controlled thermoelectric fields.
June 1, 2017: Chemical Communications: Chem Comm
Huilin Liu, Kaiwen Zhou, Xiaomo Chen, Jing Wang, Shuo Wang, Baoguo Sun
The hierarchical structuring of materials offers exciting opportunities to construct functional sensors. Multiple processes were combined to create complex materials for the selective detection of cyanoguanidine (CYA) using graphene oxide-sensitized molecularly imprinted opto-polymers (MIOP). Molecular imprinting was used to construct molecular-scale analyte-selective cavities, graphene oxide was introduced to provide a platform for the polymerization, and increase the stability and binding kinetic properties, and 3-methacryloxy propyl trimethoxy silane-modified quantum dots were combined with a functional monomer to increase the fluorescence quantum yield...
November 15, 2017: Food Chemistry
Michele Dipalo, Hayder Amin, Laura Lovato, Fabio Moia, Valeria Caprettini, Gabriele C Messina, Francesco Tantussi, Luca Berdondini, Francesco De Angelis
Three-dimensional vertical micro- and nanostructures can enhance the signal quality of multielectrode arrays and promise to become the prime methodology for the investigation of large networks of electrogenic cells. So far, access to the intracellular environment has been obtained via spontaneous poration, electroporation, or by surface functionalization of the micro/nanostructures; however, these methods still suffer from some limitations due to their intrinsic characteristics that limit their widespread use...
June 14, 2017: Nano Letters
Yunqiu Kelly Luo, Jinsong Xu, Tiancong Zhu, Guanzhong Wu, Elizabeth J McCormick, Wenbo Zhan, Mahesh R Neupane, Roland K Kawakami
Two-dimensional (2D) materials provide a unique platform for spintronics and valleytronics due to the ability to combine vastly different functionalities into one vertically stacked heterostructure, where the strengths of each of the constituent materials can compensate for the weaknesses of the others. Graphene has been demonstrated to be an exceptional material for spin transport at room temperature; however, it lacks a coupling of the spin and optical degrees of freedom. In contrast, spin/valley polarization can be efficiently generated in monolayer transition metal dichalcogenides (TMD) such as MoS2 via absorption of circularly polarized photons, but lateral spin or valley transport has not been realized at room temperature...
June 14, 2017: Nano Letters
Faguang Yan, Lixia Zhao, Amalia Patanè, PingAn Hu, Xia Wei, Wengang Luo, Dong Zhang, Quanshan Lv, Qi Feng, Chao Shen, Kai Chang, Laurence Eaves, Kaiyou Wang
The integration of different two-dimensional materials within a multilayer van der Waals (vdW) heterostructure offers a promising technology for high performance opto-electronic devices such as photodetectors and light sources. Here we report on the fabrication and electronic properties of vdW heterojunction diodes composed of the direct band gap layered semiconductors InSe and GaSe and transparent monolayer graphene electrodes. We show that the type II band alignment between the two layered materials and their distinctive spectral response, combined with the short channel length and low electrical resistance of graphene electrodes, enable efficient generation and extraction of photoexcited carriers from the heterostructure even when no external voltage is applied...
July 7, 2017: Nanotechnology
Brian J Kinsman, Haley N Nation, Sean D Stocker
PURPOSE OF REVIEW: The central nervous system plays a pivotal role in the regulation of extracellular fluid volume and consequently arterial blood pressure. Key hypothalamic regions sense and integrate neurohumoral signals to subsequently alter intake (thirst and salt appetite) and output (renal excretion via neuroendocrine and autonomic function). Here, we review recent findings that provide new insight into such mechanisms that may represent new therapeutic targets. RECENT FINDINGS: Implementation of cutting edge neuroscience approaches such as opto- and chemogenetics highlight pivotal roles of circumventricular organs to impact body fluid homeostasis...
June 2017: Current Hypertension Reports
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