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Sargis Hakobyan, Valentin J Wittwer, Kutan Gürel, Aline S Mayer, Stéphane Schilt, Thomas Südmeyer
We demonstrate, to the best of our knowledge, the first carrier-envelope offset (CEO) frequency stabilization of a GHz femtosecond laser based on opto-optical modulation (OOM) of a semiconductor saturable absorber mirror (SESAM). The 1.05-GHz laser is based on a Yb:CALGO gain crystal and emits sub-100-fs pulses with 2.1-W average power at a center wavelength of 1055 nm. The SESAM plays two key roles: it starts and stabilizes the mode-locking operation and is simultaneously used as an actuator to control the CEO frequency...
November 15, 2017: Optics Letters
Adam Q Bauer, Andrew W Kraft, Grant A Baxter, Patrick W Wright, Matthew D Reisman, Annie R Bice, Jasmine J Park, Michael R Bruchas, Abraham Z Snyder, Jin-Moo Lee, Joseph P Culver
Brain connectomics has expanded from histological assessment of axonal projection connectivity (APC) to encompass resting state functional connectivity (RS-FC). RS-FC analyses are efficient for whole-brain mapping, but attempts to explain aspects of RS-FC (e.g., interhemispheric RS-FC) based on APC have been only partially successful. Neuroimaging with hemoglobin alone lacks specificity for determining how activity in a population of cells contributes to RS-FC. Wide-field mapping of optogenetically defined connectivity could provide insights into the brain's structure-function relationship...
November 9, 2017: Cerebral Cortex
Lumanyano L A Ntoi, Blenerhassitt E Buitendach, Karel Grobler von Eschwege
Variations in the electromagnetic wavelengths of absorption and reflection of molecules do not only make life colorful, but is often of central importance in solar energy conversion and opto-electronic information processing and transfer. Dithizone and its derivatives and complexes are, to our knowledge, probably the most "colorful" compound, being responsive to no less than seven different external stimuli that effects color change. Apart from a more detailed discussion of the cyclic voltammetry and observed electrochromism in the SCH3-substituted free ligand and mercury complex, concentratochromism, solvatochromism, halochromism, thermochromism and chronochromism in the ligand, and photochromism in the carboxy-functionalized phenylmercury(II) complex are also presented here...
November 10, 2017: Journal of Physical Chemistry. A
Taha Ayari, Chris Bishop, Matthew B Jordan, Suresh Sundaram, Xin Li, Saiful Alam, Youssef ElGmili, Gilles Patriarche, Paul L Voss, Jean Paul Salvestrini, Abdallah Ougazzaden
The transfer of GaN based gas sensors to foreign substrates provides a pathway to enhance sensor performance, lower the cost and extend the applications to wearable, mobile or disposable systems. The main keys to unlocking this pathway is to grow and fabricate the sensors on large h-BN surface and to transfer them to the flexible substrate without any degradation of the performances. In this work, we develop a new generation of AlGaN/GaN gas sensors with boosted performances on a low cost flexible substrate...
November 9, 2017: Scientific Reports
Takeshi Arai, Soshi Iimura, Junghwan Kim, Yoshitake Toda, Shigenori Ueda, Hideo Hosono
Transparent bipolar semiconductors (TBSCs) are in demand for transparent electronics to serve as the basis for next generation optoelectronic devices. However, the poor carrier controllability in wide-bandgap materials makes the realization of a bipolar nature difficult. Only two materials, CuInO2 and SnO, have been reported as TBSCs. To satisfy demand for the coexistence of transparency and bipolarity, we propose a design concept with three strategies; choice of early transition metals (eTM) such as Y(3+) and Zr(4+) for improving controllability of carrier doping, design of chemical bonds to obtain an appropriate band structure for bipolar doping, and use of a forbidden band-edge transition to retain transparency...
November 17, 2017: Journal of the American Chemical Society
Weidong Song, Rupeng Wang, Xingfu Wang, Dexiao Guo, Hang Chen, Yuntao Zhu, Liu Liu, Yu Zhou, Qian Sun, Li Wang, Shuti Li
Micro/nanowire-based devices have been envisioned as a promising new route towards improved electronics and opto-electronics applications, which attracts considerable research interests. However, suffering from applicable strategies to synthesize uniform core-shell structures to meet the requirement for the investigations of electrical transport behaviors along length direction or HEMT devices, heterojunction wire-based electronics have been explored limitedly. In the present work, GaN/AlN/AlGaN core-shell heterojunction microwires on patterned Si substrates were synthesized without any catalyst via MOCVD...
November 7, 2017: ACS Applied Materials & Interfaces
Zhenhai Yang, Zhaolang Liu, Jiang Sheng, Wei Guo, Yuheng Zeng, Pingqi Gao, Jichun Ye
Recently, silicon single nanowire solar cells (SNSCs) serving as the sustainable self-power sources have been integrated into optoelectronic nanodevices under the driver of technology and economy. However, conventional SNSC cannot provide the minimum energy consumption for the operation of nanodevices due to its low power conversion efficiency (PCE). Here, we propose an innovative approach to combine the n-type silicon nanowires (SiNWs) with p-type poly(3,4-ethylthiophene):poly(styrenesulfonate) (PEDOT:PSS) to form the p (+) n heterojunction, which shows superior opto-electric performances...
November 6, 2017: Scientific Reports
Thomas Seidl, Daniel Linke, Martin Lames
Spatio-temporal parameters like step length, step frequency and ground contact time are directly related to sprinting performance. There is still a lack of knowledge, however, on how these parameters interact. Recently, various algorithms for the automatic detection of step parameters during sprint running have been presented which have been based on data from motion capture systems, video cameras, opto-electronic systems or Inertial measurement units. However, all of these methods suffer from at least one of the following shortcomings: they are (a) not applicable for more than one sprinter simultaneously, (b) only capable of capturing a small volume or (c) do not provide accurate spatial parameters...
October 12, 2017: Journal of Biomechanics
P Kostic, A LoMauro, A Larsson, G Hedenstierna, P Frykholm, A Aliverti
BACKGROUND: Studies aimed at maintaining intraoperative lung volume to reduce post-operative pulmonary complications have been inconclusive because they mixed up the effect of general anesthesia and the surgical procedure. Our aims were to study: (1) lung volume during the entire course of anesthesia without the confounding effects of surgical procedures; (2) the combination of three interventions to maintain lung volume; and (3) the emergence phase with focus on the restored activation of the respiratory muscles...
November 3, 2017: Acta Anaesthesiologica Scandinavica
María C Gélvez-Rueda, Nicolas Renaud, Ferdinand C Grozema
The fundamental opto-electronic properties of organic-inorganic hybrid perovskites are strongly affected by their structural parameters. These parameters are particularly critical in formamidinium lead iodide (FAPbI3), in which its large structural disorder leads to a non-perovskite yellow phase that hinders its photovoltaic performance. A clear understanding of how the structural parameters affect the opto-electronic properties is currently lacking. We have studied the opto-electronic properties of FAPbI3 using microwave conductivity measurements...
October 26, 2017: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Abu Riduan Md Foisal, Afzaal Qamar, Hoang-Phuong Phan, Toan Dinh, Khoa-Nguyen Tuan, Philip Tanner, Erik W Streed, Dzung Viet Dao
This letter reports a giant opto-piezoresistive effect in p-3C-SiC/p-Si heterostructure under visible-light illumination. The p-3C-SiC/p-Si heterostructure has been fabricated by growing a 390 nm p-type 3C-SiC on a p-type Si substrate using the low pressure chemical vapor deposition (LPCVD) technique. The gauge factor of the heterostructure was found to be 28 under a dark condition; however, it significantly increased to about -455 under illumination of 635 nm wavelength at 3.0 mW/cm(2). This gauge factor is over 200 times higher than that of commercial metal strain gauge, 16 times higher than that of 3C-SiC thinfilm, and approximately 5 times larger than that of bulk Si...
November 7, 2017: ACS Applied Materials & Interfaces
Md Ashraful Islam, Jared Church, Changseok Han, Hee-Suk Chung, Eunji Ji, Jong Hun Kim, Nitin Choudhary, Gwan-Hyoung Lee, Woo Hyoung Lee, Yeonwoong Jung
Two-dimensional molybdenum disulfide (2D MoS2) presents extraordinary optical, electrical, and chemical properties which are highly tunable by engineering the orientation of constituent 2D layers. 2D MoS2 films with vertically-aligned layers exhibit numerous 2D edge sites which are predicted to offer superior chemical reactivity owing to their enriched dangling bonds. This enhanced chemical reactivity coupled with their tunable band gap energy can render the vertical 2D MoS2 unique opportunities for environmental applications that go beyond the conventional applications of horizontal 2D MoS2 in electronics/opto-electronics...
November 2, 2017: Scientific Reports
Gyuhyon Lee, David A Scripka, Brent Wagner, Naresh N Thadhani, Zhitao Kang, Christopher J Summers
A novel 2D-surface shock pressure sensor is designed and tested based on 1D-Photonic Crystal, i.e., Distributed Bragg Reflector Multilayer (DBR/ML) structures. The fast opto-mechanical response of these structures to changes in layer thicknesses and refractive indices are ideally suited for dynamic pressure sensing. They offer the potential to minimize acoustic impedance mismatch between the material layers, and most importantly, the potential to monitor both temporal and spatial (lateral) variations during shock compression...
October 30, 2017: Optics Express
Arafeh Bigdeli, Forough Ghasemi, Hamed Golmohammadi, Samira Abbasi-Moayed, M Amin Farahmand Nejad, Nafiseh Fahimi-Kashani, Somayeh Jafarinejad, Maryam Shahrajabian, M Reza Hormozi-Nezhad
As in many other methods that have integrated nanoparticles (NPs), the chemical nose/tongue strategy has also progressed greatly since the entrance of NPs into this field. The fascinating tunable physicochemical properties of NPs have made them powerful candidates for array-based sensing platforms and have enabled the development of real-time, sensitive and portable systems that are able to target complex mixtures of analytes. In particular, the unique optical properties of NPs have a key role in providing promising array-based sensing approaches...
November 9, 2017: Nanoscale
Pritam Mukhopadhyay, Sudhir Kumar Keshri, Deepak Asthana, Sonam Chorol, Yogendra Kumar
Three classes of donor-acceptor pi-extended chromophores (1-12) were synthesized via phosphite-mediated cross-coupling reaction in which the anhydride or imide-based pi-acceptors (A) and the number of tetrathiafulvalene (TTF) donors (D) were systematically changed. Large pi-rings like benzoperylene and coronene were integrated with the TTF unit for the first time, overcoming their high insolubility. The anhydride and the imide groups in the pi-acceptors can significantly alter the frontier orbitals and influence the opto-electronic properties...
October 27, 2017: Chemistry: a European Journal
Pablo Ares, Juan José Palacios, Gonzalo Abellán, Julio Gómez-Herrero, Félix Zamora
Antimonene, defined in sensu stricto as a single layer of antimony atoms, is recently the focus of numerous theoretical works predicting a variety of interesting properties and is quickly attracting the attention of the scientific community. However, what places antimonene in a different category from other 2D crystals is its strong spin-orbit coupling and a drastic evolution of its properties from the monolayer to the few-layer system. The recent isolation of this novel 2D material pushes the interest for antimonene even further...
October 27, 2017: Advanced Materials
Thorsten Deilmann, Michael Rohlfing
One- and two-dimensional materials are being intensively investigated due to their interesting properties for next-generation optoelectronic devices. Among these, armchair-edged graphene nanoribbons are very promising candidates with optical properties that are dominated by excitons. In the presence of additional charges, trions (i.e., charged excitons) can occur in the optical spectrum. With our recently developed first-principle many-body approach (Phys. Rev. Lett. 116, 196804), we predict strongly bound trions in free-standing nanoribbons with large binding energies of 140-660 meV for widths of 14...
October 30, 2017: Nano Letters
Insik Hwang, Jaehyun Kim, Minkyung Lee, Min-Wook Lee, Hee-Joong Kim, Hyuck-In Kwon, Do Kyung Hwang, Myunggil Kim, Haeyoung Yoon, Yong-Hoon Kim, Sung Kyu Park
Purified semiconducting single-walled carbon nanotubes (sc-SWCNTs) have been researched for optoelectronic applications due to their high absorption coefficient from the visible to even the near-infrared (NIR) region. Nevertheless, the insufficient electrical characteristics and incompatibility with conventional CMOS processing have limited their wide utilization in this emerging field. Here, we demonstrate highly detective and wide spectral/dynamic range phototransistors incorporating floated heterojunction active layers which are composed of low-temperature sol-gel processed n-type amorphous indium gallium zinc oxide (a-IGZO) stacked with a purified p-type sc-SWCNT layer...
November 9, 2017: Nanoscale
Qionghua Zhou, Qiang Li, Shijun Yuan, Qian Chen, Jinlan Wang
The poor environmental stability of black phosphorous (BP) seriously limits its practical applications in (opto)electronics. Other than capping protective layers on its surface, herein we propose a new strategy to improve BP's ambient stability by engineering the interlayer interactions. Our first-principles calculations demonstrate that enlarging the interlayer spacing can effectively shift the conduction band minimum down to suppress the generation of superoxide and the enlargement can be achieved by intercalating small molecules like H2 and He into BP...
November 8, 2017: Physical Chemistry Chemical Physics: PCCP
Karalikkadan Ashhar, Cheong Boon Soh, Keng He Kong
Analysis of bilateral gait symmetry and coordination is important in rehabilitation after lower-extremity trauma, prosthesis and neurovascular diseases. Moreover, it can act as a precursor of freezing of gait in Parkinson's disease. Current methods for gait symmetry analysis include Opto-electronic systems using multiple high-speed cameras, instrumented platforms etc. which are complex and costly. We propose a low-cost, wearable ultrasonic sensor network using readily available components, which is easy to use, portable and does not require complex calibration procedures...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
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