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https://www.readbyqxmd.com/read/28819151/the-investigation-of-stress-in-freestanding-gan-crystals-grown-from-si-substrates-by-hvpe
#1
Moonsang Lee, Dmitry Mikulik, Mino Yang, Sungsoo Park
We investigate the stress evolution of 400 µm-thick freestanding GaN crystals grown from Si substrates by hydride vapour phase epitaxy (HVPE) and the in situ removal of Si substrates. The stress generated in growing GaN can be tuned by varying the thickness of the MOCVD AlGaN/AlN buffer layers. Micro Raman analysis shows the presence of slight tensile stress in the freestanding GaN crystals and no stress accumulation in HVPE GaN layers during the growth. Additionally, it is demonstrated that the residual tensile stress in HVPE GaN is caused only by elastic stress arising from the crystal quality difference between Ga- and N-face GaN...
August 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28809902/tunable-low-phase-noise-microwave-signals-from-an-optically-injected-semiconductor-laser-with-opto-electronic-feedback
#2
Joseph S Suelzer, Thomas B Simpson, Preetpaul Devgan, Nicholas G Usechak
We experimentally demonstrate the generation of microwave signals with linewidths below 3 Hz and a tuning range over 35 GHz from a semiconductor laser subject to optical injection and opto-electronic feedback. The feedback loop uses neither a microwave spectral filter nor an amplifier to achieve a reduction in the microwave linewidth of six orders of magnitude. Two microwave frequencies, 25.4 and 45.9 GHz, are chosen to highlight single-sideband phase measurements of -105 and -95  dBc/Hz at a 10-kHz offset, respectively...
August 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28805396/transport-properties-of-a-two-dimensional-pbse-square-superstructure-in-an-electrolyte-gated-transistor
#3
Maryam Alimoradi Jazi, Vera A E C Janssen, Wiel H Evers, Athmane Tadjine, Christophe Delerue, Laurens D A Siebbeles, Herre S J van der Zant, Arjan J Houtepen, Daniël Vanmaekelbergh
Self-assembled nanocrystal solids show promise as a versatile platform for novel opto-electronic materials. Superlattices composed of a single layer of lead-chalcogenide and cadmium-chalcogenide nanocrystals with epitaxial connections between the nanocrystals, present outstanding questions to the community regarding their predicted band structure and electronic transport properties. However, the as-prepared materials are intrinsic semiconductors; to occupy the bands in a controlled way, chemical doping or external gating is required...
August 14, 2017: Nano Letters
https://www.readbyqxmd.com/read/28802101/flexible-biodegradable-citrate-based-polymeric-step-index-optical-fiber
#4
Dingying Shan, Chenji Zhang, Surge Kalaba, Nikhil Mehta, Gloria B Kim, Zhiwen Liu, Jian Yang
Implanting fiber optical waveguides into tissue or organs for light delivery and collection is among the most effective ways to overcome the issue of tissue turbidity, a long-standing obstacle for biomedical optical technologies. Here, we report a citrate-based material platform with engineerable opto-mechano-biological properties and demonstrate a new type of biodegradable, biocompatible, and low-loss step-index optical fiber for organ-scale light delivery and collection. By leveraging the rich designability and processibility of citrate-based biodegradable polymers, two exemplary biodegradable elastomers with a fine refractive index difference and yet matched mechanical properties and biodegradation profiles were developed...
August 4, 2017: Biomaterials
https://www.readbyqxmd.com/read/28796823/assessment-of-photocatalytic-potentiality-and-determination-of-ecotoxicity-using-plant-model-for-better-environmental-applicability-of-synthesized-copper-copper-oxide-and-copper-doped-zinc-oxide-nanoparticles
#5
Debadrito Das, Animesh Kumar Datta, Divya Vishambhar Kumbhakar, Bapi Ghosh, Ankita Pramanik, Sudha Gupta, Aninda Mandal
NPS SYNTHESIS, CHARACTERIZATION AND AZO-DYE DEGRADATION: A facile cost effective wet chemical method of synthesis is proposed for Cu-NPs, CuO-NPs and Cu-doped ZnO-NPs. The nanomaterials are opto-physically characterized for nano standard quality. Cu-doped ZnO-NPs based catalytic system is found to possess most efficient photocatalytic activity in degradation of two organic azo-dyes namely methyl red (MR) and malachite green (MG) that are released as industrial effluents in eco-environment intercollegium...
2017: PloS One
https://www.readbyqxmd.com/read/28795949/a-comprehensive-gaze-stabilization-controller-based-on-cerebellar-internal-models
#6
Lorenzo Vannucci, Egidio Falotico, Silvia Tolu, Vito Cacucciolo, Paolo Dario, Henrik Hautop Lund, Cecilia Laschi
Gaze stabilization is essential for clear vision; it is the combined effect of two reflexes relying on vestibular inputs: the vestibulocollic reflex (VCR), which stabilizes the head in space and the vestibulo-ocular reflex (VOR), which stabilizes the visual axis to minimize retinal image motion. The VOR works in conjunction with the opto-kinetic reflex (OKR), which is a visual feedback mechanism that allows to move the eye at the same speed as the observed scene. Together they keep the image stationary on the retina...
August 10, 2017: Bioinspiration & Biomimetics
https://www.readbyqxmd.com/read/28794965/efficacy-of-lung-volume-optimization-maneuver-monitored-by-optoelectronic-pletismography-in-the-management-of-congenital-diaphragmatic-hernia
#7
G Lista, I Bresesti, F Cavigioli, F Castoldi, E Lupo, A LoMauro, A Aliverti
Newborns affected by congenital diaphragmatic hernia (CDH) need cardio-respiratory stabilization before undergoing surgical repair. Open lung strategy is a well-established approach to optimize lung volume in preterm infants with Respiratory Distress Syndrome (RDS), using both High Frequency Oscillatory Ventilation (HFOV) and Conventional Mechanical Ventilation (CMV). We report a case of left CDH with severe lung hypoplasia, managed applying open lung strategy in HFOV (pre-surgery period) and in Assist-Control with Volume Guarantee (post-surgery period), guided by SpO2 changes, TcPO2 and TcPCO2 monitoring...
2017: Respiratory Medicine Case Reports
https://www.readbyqxmd.com/read/28777542/1-4-dihydropyrrolo-3-2-b-pyrroles-as-a-single-component-photoactive-layer-a-new-paradigm-for-broadband-detection
#8
Ram Kumar Canjeevaram Balasubramanyam, Ahmad E Kandjani, Christopher J Harrison, Syed Sulthan Alaudeen Abdul Haroon Rashid, Ylias M Sabri, Suresh K Bhargava, Ramanuj Narayan, Pratyay Basak, Samuel J Ippolito
Single component organic photodetectors capable of broadband light sensing represent a paradigm shift for designing flexible and inexpensive optoelectronic devices. The present study demonstrates the application of a new quadrupolar 1,4-dihydropyrrolo[3,2-b]pyrrole derivative with spectral sensitivity across 350-830 nm as a potential broadband organic photodetector (OPD) material. The amphoteric redox characteristics evinced from the electrochemical studies are exploited to conceptualize a single component OPD with ITO and Al as active electrodes...
August 10, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28771790/motoneuron-activity-is-required-for-enhancements-in-functional-recovery-after-peripheral-nerve-injury-in-exercised-female-mice
#9
Poonam B Jaiswal, Jack K Tung, Robert E Gross, Arthur W English
Inhibitory luminopsins (iLMO2) integrate opto- and chemo-genetic approaches and allow for cell-type specific inhibition of neuronal activity. When exposed to a Renilla luciferase substrate, Coelenterazine (CTZ), iLMO2 generates bioluminescence-mediated activation of its amino-terminal halorhodopsin, resulting in neuronal inhibition. Moderate daily exercise in the form of interval treadmill-training (IT) applied following a peripheral nerve injury results in enhanced motor axon regeneration and muscle fiber reinnervation in female mice...
August 3, 2017: Journal of Neuroscience Research
https://www.readbyqxmd.com/read/28769034/prediction-of-thermal-boundary-resistance-by-the-machine-learning-method
#10
Tianzhuo Zhan, Lei Fang, Yibin Xu
Thermal boundary resistance (TBR) is a key property for the thermal management of high power micro- and opto-electronic devices and for the development of high efficiency thermal barrier coatings and thermoelectric materials. Prediction of TBR is important for guiding the discovery of interfaces with very low or very high TBR. In this study, we report the prediction of TBR by the machine learning method. We trained machine learning models using the collected experimental TBR data as training data and materials properties that might affect TBR as descriptors...
August 2, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28767251/role-of-absorbing-nanocrystal-cores-in-soft-photonic-crystals-a-spectroscopy-and-sans-study
#11
Astrid Rauh, Nico Carl, Ralf Schweins, Matthias Karg
Periodic superstructures of plasmonic nanoparticles have attracted significant interest since they can support coupled plasmonic modes making them interesting for plasmonic lasing, metamaterials and as light management structures in thin-film opto-electronic devices. We have recently shown that noble metal-hydrogel core-shell colloids allow for the fabrication of highly ordered 2-dimensional plasmonic lattices that show surface lattice resonances as the result of plasmonic/diffractive coupling [Adv. Optical Mater...
August 2, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28765148/changes-in-retinal-venular-oxygen-saturation-predict-activity-of-proliferative-diabetic-retinopathy-3-months-after-panretinal-photocoagulation
#12
Thomas Lee Torp, Ryo Kawasaki, Tien Yin Wong, Tunde Peto, Jakob Grauslund
BACKGROUND/AIMS: Proliferative diabetic retinopathy (PDR) is a severe blinding condition. We investigated whether retinal metabolism, measured by retinal oximetry, may predict PDR activity after panretinal laser photocoagulation (PRP). METHODS: We performed a prospective, interventional, clinical study of patients with treatment-naive PDR. Wide-field fluorescein angiography (OPTOS, Optomap) and global and focal retinal oximetry (Oxymap T1) were performed at baseline (BL), and 3 months (3M) after PRP...
August 1, 2017: British Journal of Ophthalmology
https://www.readbyqxmd.com/read/28763029/an-opto-electronic-sensor-for-detecting-soil-microarthropods-and-estimating-their-size-in-field-conditions
#13
Csongor I Gedeon, Norbert Flórián, Péter Liszli, Beáta Hambek-Oláh, Oxána Bánszegi, Judit Schellenberger, Miklós Dombos
Methods to estimate density of soil-dwelling arthropods efficiently, accurately and continuously are critical for investigating soil biological activity and evaluating soil management practices. Soil-dwelling arthropods are currently monitored manually. This method is invasive, and time- and labor-consuming. Here we describe an infrared opto-electronic sensor for detection of soil microarthropods in the size range of 0.4-10 mm. The sensor is built in a novel microarthropod trap designed for field conditions...
August 1, 2017: Sensors
https://www.readbyqxmd.com/read/28741739/reversible-fast-and-wide-range-oxygen-sensor-based-on-nanostructured-organometal-halide-perovskite
#14
Marc-Antoine Stoeckel, Marco Gobbi, Sara Bonacchi, Fabiola Liscio, Laura Ferlauto, Emanuele Orgiu, Paolo Samorì
Nanostructured materials characterized by high surface-volume ratio hold the promise to constitute the active materials for next-generation sensors. Solution-processed hybrid organohalide perovskites, which have been extensively used in the last few years for optoelectronic applications, are characterized by a self-assembled nanostructured morphology, which makes them an ideal candidate for gas sensing. Hitherto, detailed studies of the dependence of their electrical characteristics on the environmental atmosphere have not been performed, and even the effect of a ubiquitous gas such as O2 has been widely overlooked...
July 25, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28740558/thermoelectric-la-doped-srtio3-epitaxial-layers-with-single-crystal-quality-from-nano-to-micrometers
#15
Mihai Apreutesei, Régis Debord, Mohamed Bouras, Philippe Regreny, Claude Botella, Aziz Benamrouche, Adrian Carretero-Genevrier, Jaume Gazquez, Geneviève Grenet, Stéphane Pailhès, Guillaume Saint-Girons, Romain Bachelet
High-quality thermoelectric La0.2Sr0.8TiO3 (LSTO) films, with thicknesses ranging from 20 nm to 0.7 μm, have been epitaxially grown on SrTiO3(001) substrates by enhanced solid-source oxide molecular-beam epitaxy. All films are atomically flat (with rms roughness < 0.2 nm), with low mosaicity (<0.1°), and present very low electrical resistivity (<5 × 10(-4) Ω cm at room temperature), one order of magnitude lower than standard commercial Nb-doped SrTiO3 single-crystalline substrate. The conservation of transport properties within this thickness range has been confirmed by thermoelectric measurements where Seebeck coefficients of approximately -60 μV/K have been recorded for all films...
2017: Science and Technology of Advanced Materials
https://www.readbyqxmd.com/read/28737161/linbo-sub-3-sub-surfaces-from-a-microscopic-perspective
#16
Simone Sanna, Wolf Gero Schmidt
A large number of oxides has been investigated in the last twenty years as possible new materials for various applications ranging from opto-electronics to heterogeneous catalysis. In this context, ferroelectric oxides are particularly promising. The electric polarization plays a crucial role at many oxide surfaces, and it largely determines their physical and chemical properties. Ferroelectrics offer in addition the possibility to control/switch the electric polarization and hence the surface chemistry, allowing for the realization of domain-engineered nanoscale devices such as molecular detectors or highly efficient catalysts...
July 24, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28736950/impact-of-interfacial-layers-in-perovskite-solar-cells
#17
An-Na Cho, Nam-Gyu Park
Perovskite solar cell (PCSs) is composed of organic-inorganic lead halide perovskite as light harvester. Since the first report on long-term durable 9.7% efficient solid-state perovskite solar cell in 2012, organic-inorganic halide perovskite received great attention because of its superb opto-electronic properties. As a result, a power conversion efficiency (PCE) exceeding 22% was certified. Controlling grain size and grain boundary of perovskite layer perovskite is important for attaining high efficiency...
July 23, 2017: ChemSusChem
https://www.readbyqxmd.com/read/28730469/optogenetic-control-of-ras-erk-signaling-using-the-phy-pif-system
#18
Alexander G Goglia, Maxwell Z Wilson, Daniel B DiGiorno, Jared E Toettcher
The Ras/Erk signaling pathway plays a central role in diverse cellular processes ranging from development to immune cell activation to neural plasticity to cancer. In recent years, this pathway has been widely studied using live-cell fluorescent biosensors, revealing complex Erk dynamics that arise in many cellular contexts. Yet despite these high-resolution tools for measurement, the field has lacked analogous tools for control over Ras/Erk signaling in live cells. Here, we provide detailed methods for one such tool based on the optical control of Ras activity, which we call "Opto-SOS...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28726895/a-fluorescence-electrochemical-study-of-carbon-nanodots-cnds-in-bio-and-photoelectronic-applications-and-energy-gap-investigation
#19
Zheng Zeng, Wendi Zhang, Durga M Arvapalli, Brian Bloom, Alex Sheardy, Taylor Mabe, Yiyang Liu, Zuowei Ji, Harish Chevva, David H Waldeck, Jianjun Wei
Carbon nanodots (CNDs) have attracted great attention due to their superior solubility, biocompatibility, tunable photoluminescence, and opto-electronic properties. This work describes a new fluorescence-based spectroelectrochemistry approach to simultaneously study the photoluminescence and wavelength dependent photocurrent of microwave synthesized CNDs. The fluorescence of CNDs shows selective quenching upon a reversible redox couple, ferricyanide/ferrocyanide, reaction during cyclic voltammetry. The CND modified gold slide electrode demonstrates wavelength dependent photocurrent generation during the fluorescence-electrochemical study, suggesting the potential application of CNDs in photoelectronics...
August 2, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28724994/high-resolution-on-chip-rf-photonic-signal-processor-using-brillouin-gain-shaping-and-rf-interference
#20
Amol Choudhary, Yang Liu, Blair Morrison, Khu Vu, Duk-Yong Choi, Pan Ma, Stephen Madden, David Marpaung, Benjamin J Eggleton
Integrated microwave photonics has strongly emerged as a next-generation technology to address limitations of conventional RF electronics for wireless communications. High-resolution RF signal processing still remains a challenge due to limitations in technology that offer sub-GHz spectral resolution, in particular at high carrier frequencies. In this paper, we present an on-chip high-resolution RF signal processor, capable of providing high-suppression spectral filtering, large phase shifts and ns-scale time delays...
July 19, 2017: Scientific Reports
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