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Vanousheh Rahemi, Nasrin Sarmadian, Willemien Anaf, Koen Janssens, Dirk Lamoen, Bart Partoens, Karolien De Wael
Chrome yellow refers to a group of synthetic inorganic pigments that became popular as an artist's material from the second quarter of the 19th century. The color of the pigment, in which the chromate ion acts as a chromophore, is related to its chemical composition (PbCr1-xSxO4, with 0≤x≤0.8) and crystalline structure (monoclinic/orthorhombic). Their shades range from the yellow-orange to the paler yellow tones with increasing sulfate amount. These pigments show remarkable signs of degradation after limited time periods...
February 23, 2017: Analytical Chemistry
Takashi Tokuda, Satoki Noguchi, Satoru Iwasaki, Hiroaki Takehara, Toshihiko Noda, Kiyotaka Sasagawa, Jun Ohta, Takashi Tokuda, Satoki Noguchi, Satoru Iwasaki, Hiroaki Takehara, Toshihiko Noda, Kiyotaka Sasagawa, Jun Ohta, Toshihiko Noda, Kiyotaka Sasagawa, Satoru Iwasaki, Takashi Tokuda, Satoki Noguchi, Hiroaki Takehara, Jun Ohta
CMOS-based opto-electronic neural interface devices are presented. The devices are designed with target application of in vitro and in vivo optogenetics. Two types of the opto-electronic neural interface devices are presented. One is single-chip type device for on-chip optogenetics, and the other is multi-chip type device with flexibility and wide-area coverage for in vivo optogenetics on brain. Design, packaging and functional evaluations are presented.
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Sudha Janardhanan Devaki, Reshma Lali Raveendran, Nishanth Kumar Sasidharan
Design of liquid crystalline hydrogels knitted with silver nanoparticles in macroscopic ordering are becoming subject of research interest due to their promising multifunctional applications in biomedical and opto-electronic applications. The present work describes the development of liquid crystalline Schiff-based hydrogel decorated with silver nanoparticles and demonstration of its antifungal applications. Schiff base was prepared from polyglucanaldehyde and chitosan and the former was prepared by the oxidation of amylose (polyglucopyranose) isolated from abundantly available unutilised jackfruit seed starch...
February 21, 2017: Bioconjugate Chemistry
Seongjun Park, Yuanyuan Guo, Xiaoting Jia, Han Kyoung Choe, Benjamin Grena, Jeewoo Kang, Jiyeon Park, Chi Lu, Andres Canales, Ritchie Chen, Yeong Shin Yim, Gloria B Choi, Yoel Fink, Polina Anikeeva
Optogenetic interrogation of neural pathways relies on delivery of light-sensitive opsins into tissue and subsequent optical illumination and electrical recording from the regions of interest. Despite the recent development of multifunctional neural probes, integration of these modalities in a single biocompatible platform remains a challenge. We developed a device composed of an optical waveguide, six electrodes and two microfluidic channels produced via fiber drawing. Our probes facilitated injections of viral vectors carrying opsin genes while providing collocated neural recording and optical stimulation...
February 20, 2017: Nature Neuroscience
Maxwell Reinhardt, Simon Dalgleish, Yoshiaki Shuku, Louisa Reissig, Michio M Matsushita, Jason Crain, Kunio Awaga, Neil Robertson
The structure and electronic properties of a novel cobalt half sandwich complex of cyclopentadiene (Cp) and diaminonaphthalene (DAnap) [CpCo(DAnap)] are described and compared to the previously reported diaminobenzene derivative [CpCo(DAbnz)] in view of their potential for (opto)electronic device application. Both complexes show stable redox processes, tunable through the diaminoacene ligand, and show strong absorption in the visible region, with additional transitions stretching into the near infrared (NIR)...
February 20, 2017: Physical Chemistry Chemical Physics: PCCP
Tapas Majumdar, Basudeb Haldar, Arabinda Mallick
A simple strategy is proposed to design and develop an intelligent device based on dual channel ion responsive spectral properties of a commercially available molecule, harmine (HM). The system can process different sets of opto-chemical inputs generating different patterns as fluorescence outputs at specific wavelengths which can provide an additional level of protection exploiting both password and pattern recognitions. The proposed system could have the potential to come up with highly secured combinatorial locks at the molecular level that could pose valuable real time and on-site applications for user authentication...
February 20, 2017: Scientific Reports
Dai Dong, Da Fang, Hairong Li, Caixia Zhu, Xianghua Zhao, Jiewei Li, Lingzhi Jin, Linghai Xie, Lin Chen, Jianfeng Zhao, Hongmei Zhang, Wei Huang
A novel perfluoro-1,4-phenylenyl 6H-indolo[2,3-b]quinoxaline derivative (TFBIQ) was designed and synthesized via C-H direct arylation. The opto-electrical properties of the obtained TFBIQ were fully characterized by UV-vis and photoluminescence, cyclic voltammetry, film morphology and Alq3-based green organic light emitting diodes (OLEDs). Device A using 0.5 nm thick TFBIQ as the interfacial modification layer exhibits the best five advantages of device performance including the lowest minimum turn-on voltage (Von) as low as 3...
February 18, 2017: Chemistry, An Asian Journal
Khokan Roy, Surajit Kayal, Freek Ariese, Andrew Beeby, Siva Umapathy
Femtosecond transient absorption (fs-TA) and Ultrafast Raman Loss Spectroscopy (URLS) have been applied to reveal the excited state dynamics of bis(phenylethynyl)benzene (BPEB), a model system for one-dimensional molecular wires that have numerous applications in opto-electronics. It is known from the literature that in the ground state BPEB has a low torsional barrier, resulting in a mixed population of rotamers in solution at room temperature. For the excited state this torsional barrier had been calculated to be much higher...
February 14, 2017: Journal of Chemical Physics
Matthew J Byrd, Erman Timurdogan, Zhan Su, Christopher V Poulton, Nicholas M Fahrenkopf, Gerald Leake, Douglas D Coolbaugh, Michael R Watts
We propose a mode-evolution-based coupler for high saturation power germanium-on-silicon photodetectors. This coupler uniformly illuminates the intrinsic germanium region of the detector, decreasing saturation effects, such as carrier screening, observed at high input powers. We demonstrate 70% more photocurrent generation (9.1-15.5 mA) and more than 40 times higher opto-electrical bandwidth (0.7-31 GHz) than conventional butt-coupled detectors under high-power illumination. The high-power and high-speed performance of the device, combined with the compactness of the coupling method, will enable new applications for integrated silicon photonics systems...
February 15, 2017: Optics Letters
Francois Parnet, Julien Fade, Noé Ortega-Quijano, Goulc'hen Loas, Ludovic Frein, Mehdi Alouini
We report the design and optimization of an active polarimetric imaging demonstrator operating at 1.55 μm that is based on the orthogonality breaking technique. It relies on the use of a fibered dual-frequency dual-polarization source raster scanned over the scene. A dedicated opto-electronic detection chain is developed to demodulate the optical signal backscattered at each location of the scene in real time, providing multivariate polarimetric image data in one single scan with limited acquisition time. We experimentally show on a homemade scene that contrast maps can be built to reveal hidden dichroic objects over a depolarizing background, as well as their orientation...
February 15, 2017: Optics Letters
Dae Seok Kim, Apiradee Honglawan, Shu Yang, Dong Ki Yoon
Manipulation of nanomaterials such as nanoparticles (NPs) and nanorods (NRs) to make clusters is of significant interest in material science and nanotechnology due to the unusual collective opto-electric properties in such structures that cannot be found in the individual NPs. This work demonstrates an effective way to arrange NP clusters (NPCs) to make the desired arrays based on removable and NP-guidable liquid crystalline template using sublimation and reconstruction phenomenon. The position of the NPCs is precisely controlled by the defect structure of the liquid crystal (LC), namely toric focal conic domains (TFCDs), during thermal annealing to construct the LC and corresponding NPC structures...
February 16, 2017: ACS Applied Materials & Interfaces
Isabel N Christie, Jack A Wells, Sergey Kasparov, Alexander V Gourine, Mark F Lythgoe
Neurovascular coupling describes the link between neuronal activity and cerebral blood flow. This relationship has been the subject of intense scrutiny, with most previous work seeking to understand temporal correlations that describe neurovascular coupling. However, to date, the study of spatial correlations has been limited to two-dimensional mapping of neuronal or vascular derived signals emanating from the brain's surface, using optical imaging techniques. Here, we investigate spatial correlations of neurovascular coupling in three dimensions, by applying a single 10 ms pulse of light to trigger optogenetic activation of cortical neurons transduced to express channelrhodopsin2, with concurrent fMRI...
February 8, 2017: Scientific Reports
Qiankun Wang, Johannes Frisch, Martin Herder, Stefan Hecht, Norbert Koch
Light-switching-induced changes in the electronic properties of photochromic diarylethene, i.e., 1,2-bis(2-methyl-5-p-tolylthiophen-3-yl)cyclopent-1-ene (DAE1), thin films at interfaces to a gold electrode and two polymer semiconductors are investigated by direct and inverse photoelectron spectroscopy. The photoisomerization is achieved by in situ irradiation of ultraviolet and visible light. Efficient and reversible switching between the open and closed isomers of DAE1 is evidenced at all interfaces, with profound impact on the energy-level alignment...
February 7, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Amaury François, Sarah A Low, Elizabeth I Sypek, Amelia J Christensen, Chaudy Sotoudeh, Kevin T Beier, Charu Ramakrishnan, Kimberly D Ritola, Reza Sharif-Naeini, Karl Deisseroth, Scott L Delp, Robert C Malenka, Liqun Luo, Adam W Hantman, Grégory Scherrer
Pain thresholds are, in part, set as a function of emotional and internal states by descending modulation of nociceptive transmission in the spinal cord. Neurons of the rostral ventromedial medulla (RVM) are thought to critically contribute to this process; however, the neural circuits and synaptic mechanisms by which distinct populations of RVM neurons facilitate or diminish pain remain elusive. Here we used in vivo opto/chemogenetic manipulations and trans-synaptic tracing of genetically identified dorsal horn and RVM neurons to uncover an RVM-spinal cord-primary afferent circuit controlling pain thresholds...
February 22, 2017: Neuron
Li Liu, Yue Yang, Zhihua Li, Xing Jin, Wenqin Mo, Xing Liu
We propose and experimentally demonstrate a continuously tunable all-optical microwave filter using a silicon opto-mechanical microring resonator (MRR). By finely adjusting the pump light with submilliwatt power level, transmission spectrum of the MRR could be continuously shifted based on the nonlinear effects, including the opto-mechanical effect and thermo-optic effect. Therefore, in the case of optical single sideband (OSSB) modulation, the frequency intervals between the optical carrier (near one MRR resonance) and the corresponding resonance could be flexibly manipulated, which is the critical factor to achieve continuously tunable microwave photonic filter (MPF)...
January 23, 2017: Optics Express
Qizhuang Cen, Yitang Dai, Feifei Yin, Yue Zhou, Jianqiang Li, Jian Dai, Lan Yu, Kun Xu
An opto-electronic oscillator (OEO) scheme which operates at "chirp oscillation" mode and generates low-phase-noise, frequency-swept microwave is proposed and experimentally demonstrated. This frequency-swept OEO is achieved by embedding a rapidly frequency-scanning microwave filter in an opto-electronic cavity. The filter has fixed passband while its center frequency scans rapidly and periodically at cavity round-trip time, covering a large frequency range (~GHz). Experimentally, the generated frequency-swept microwave is linear frequency-modulated continuous wave (FMCW) which centers at 7 GHz with 1-GHz bandwidth...
January 23, 2017: Optics Express
Jeffrey O White, Mark Harfouche, John Edgecumbe, Naresh Satyan, George Rakuljic, Vijay Jayaraman, Christopher Burgner, Amnon Yariv
In a high power fiber amplifier, a frequency-chirped seed interrupts the coherent interaction between the laser and Stokes waves, raising the threshold for stimulated Brillouin scattering (SBS). Moving the external mirror of a vertical cavity surface-emitting diode laser 0.2 μm in 10 μs can yield a frequency chirp of 5×10<sup>17</sup>  Hz/s at a nearly constant output power. Opto-electronic feedback loops can linearize the chirp, and stabilize the output power. The linear variation of phase with time allows multiple amplifiers to be coherently combined using a frequency shifter to compensate for static and dynamic path length differences...
January 20, 2017: Applied Optics
Melbert Jeem, Lihua Zhang, Junya Ishioka, Tamaki Shibayama, Tomio Iwasaki, Takahiko Kato, Seiichi Watanabe
When applied in opto-electronic devices, a ZnO semiconductor dominantly absorbs or emits ultraviolet light because of its direct electron transition through a wide energy bandgap. On the contrary, crystal defects and nanostructure morphology are the chief key factors for indirect, interband transitions of ZnO opto-electronic devices in the visible light range. By ultraviolet illumination in ultrapure water, here we demonstrate a conceptually unique approach to tune the shape of ZnO nanorods from tapered to capped-end via apical surface morphology control...
February 3, 2017: Nano Letters
Jun Hyung Lim, Seung Muk Lee, Hyun-Suk Kim, Hyun You Kim, Jozeph Park, Seung-Boo Jung, Geun Chul Park, Jungho Kim, Jinho Joo
We synthesized ZnO nanorods (NRs) using simple hydrothermal method, with the simultaneous incorporation of gallium (Ga) and indium (In), in addition, investigated the co-doping effect on the morphology, microstructure, electronic structure, and electrical/optical properties. The growth behavior of the doped NRs was affected by the nuclei density and polarity of the (001) plane. The c-axis parameter of the co-doped NRs was similar to that of undoped NRs due to the compensated lattice distortion caused by the presence of dopants that are both larger (In(3+)) and smaller (Ga(3+)) than the host Zn(2+) cations...
February 3, 2017: Scientific Reports
Sébastien Hartmann, Wolfgang Elsäßer
Initially, ghost imaging (GI) was demonstrated with entangled light from parametric down conversion. Later, classical light sources were introduced with the development of thermal light GI concepts. State-of-the-art classical GI light sources rely either on complex combinations of coherent light with spatially randomizing optical elements or on incoherent lamps with monochromating optics, however suffering strong losses of efficiency and directionality. Here, a broad-area superluminescent diode is proposed as a new light source for classical ghost imaging...
February 2, 2017: Scientific Reports
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