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https://www.readbyqxmd.com/read/28544211/highly-luminescent-and-ultra-stable-cspbbr3-pervoskite-quantum-dots-silica-alumina-monolith
#1
Zhichun Li, Long Kong, Shouqiang Huang, Liang Li
We successfully prepared QDs-silica/alumina monolith (QDs-SAM) by a simple sol-gel reaction of Al-Si single precursors with CsPbBr3 QDs blended in toluene solution, without adding water and catalyst. The resultant transparent monolith exhibits high photoluminescence quantum yields (PLQY) up to 90%, and good photostability under strong illumination of blue light for 300 h. We demonstrated that the preliminary ligand exchange of didodecyl dimethyl ammonium bromide (DDAB) was very important to protect CsPbBr3 QDs from the surface damages during sol-gel reaction, which not only allowed us to maintain the original optical properties of CsPbBr3 QDs but also avoided the aggregation of QDs and make the monolith transparent...
May 24, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28544039/cofactor-free-direct-photoactivation-of-enoate-reductases-for-asymmetric-reduction-of-c-c-bonds
#2
Sahng Ha Lee, Da Som Choi, Milja Pesic, Yang Woo, Caroline Paul, Frank Hollmann, Chan Beum Park
Enoate reductases from the family of Old Yellow Enzymes (OYEs) can catalyze stereoselective trans-hydrogenation of activated C=C bonds. Here, we report visible light-driven activation of OYEs through NAD(P)H-free, direct transfer of photoexcited electrons from xanthene dyes to the prosthetic flavin moiety. Our spectroscopic and electrochemical analyses verified spontaneous association of rose bengal and its derivatives with OYEs. Illumination of a white light-emitting-diode triggered photoreduction of OYEs by xanthene dyes, which facilitated the enantioselective reduction of C=C bonds in the absence of NADH...
May 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28542006/an-efficient-affordable-optically-stimulated-luminescent-osl-annealer
#3
Sara A Abraham, Samuel J Frank, Kimberlee J Kearfott
Optically stimulated luminescent (OSL) dosimeters are devices used for measuring doses of ionizing radiation. Signal is stored within an OSL material so that when stimulated with light, light of a specific wavelength is emitted in proportion to the integrated ionizing radiation dose. Each interrogation of the material results in the loss of a small fraction of signal, thus allowing multiple interrogations leading to more accurate measurements of dose. In order to reuse a dosimeter, the residual signals from prior doses must be taken into account and subtracted from current readings, adding uncertainty to any future measurements...
July 2017: Health Physics
https://www.readbyqxmd.com/read/28541652/polymer-as-an-additive-in-the-emitting-layer-for-high-performance-quantum-dot-light-emitting-diodes
#4
Feng Liang, Yuan Liu, Yun Hu, YingLi Shi, Yuqiang Liu, Zhao-Kui Wang, Xuedong Wang, Baoquan Sun, Liang-Sheng Liao
A facile but effective method is proposed to improve the performance of quantum dot light-emitting diodes (QLEDs) by incorporating a polymer, poly (9-vinlycarbazole) (PVK), as an additive into the CdSe/CdS/ZnS quantum dots (QDs) emitting layer (EML). It is found that the charge balance of the device with the PVK-added EML was greatly improved. In addition, the film morphology of the hole-transporting layer (HTL) which is adjacent to the EML is substantially improved. The surface roughness of the HTL is reduced from 5...
May 25, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28541046/radical-silyldifluoromethylation-of-electron-deficient-alkenes
#5
Vyacheslav I Supranovich, Vitalij V Levin, Marina I Struchkova, Alexander A Korlyukov, Alexander D Dilman
A reaction of bromo- and iododifluoromethyl-substituted silanes with electron-deficient alkenes in the presence of an N-heterocyclic carbene borane complex is described. The reaction is performed under irradiation with light-emitting diodes and proceeds via a radical chain mechanism. The resulting products, the functionalized silicon reagents, can undergo chemoselective transformations involving either the silyldifluoromethyl fragment or the functional group.
May 25, 2017: Organic Letters
https://www.readbyqxmd.com/read/28540864/enhancement-of-external-quantum-efficiency-and-quality-of-heterojunction-white-leds-by-varying-the-size-of-zno-nanorods
#6
N Bano, I Hussain, S Sawaf, Abeer Alshammari, F Saleemi
The size of ZnO nanorods (NRs) plays an important role in tuning the external quantum efficiency (EQE) and quality of light generated by white light emitting diodes (LEDs). In this work, we report on the enhancement of EQE and the quality of ZnO NR-based hetrojunction white LEDs fabricated on a p-GaN substrate using a low temperature solution method. Cathodoluminescence spectra demonstrate that ultraviolet (UV) emission decreases and visible deep band emission increases with an increase in the length of the ZnO NRs...
June 16, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28538310/enhancing-digital-video-analysis-of-bar-kinematics-in-weightlifting-a-case-study
#7
Torstein E Dæhlin, Tron Krosshaug, Loren Z F Chiu
Dæhlin, TE, Krosshaug, T, and Chiu, LZF. Enhancing digital video analysis of bar kinematics in weightlifting: a case study. J Strength Cond Res 31(6): 1592-1600, 2017-Weightlifting technique can be objectively assessed from two-dimensional video recordings. Despite its importance, participants' bar trajectories in research involving the snatch or clean exercises are often not reported, potentially due to the time required to digitize video. The purpose of this investigation was to evaluate the use of a light-emitting diode (LED)-based marker, digital video, and open-source software to automatically track the bar end during weightlifting exercises...
June 2017: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/28538060/effect-of-low-level-laser-and-light-emitting-diode-on-inferior-alveolar-nerve-recovery-after-sagittal-split-osteotomy-of-the-mandible-a-randomized-clinical-trial-study
#8
Seyed Hasan Mohajerani, Faraj Tabeie, Mehdi Bemanali, Reza Tabrizi
PURPOSE: The major concern of sagittal split osteotomy (SSO) is the neurosensory disturbance. The authors investigated the effect of low-level laser therapy and light-emitting diode on the inferior alveolar nerve recovery after SSO. METHODS: In this double-blinded randomized clinical trial, 20 subjects with inferior alveolar nerve injury after SSO of the mandible were studied. Neurosensory recovery was assessed by 6 tests: visual analog scale (VAS), brush stroke, 2-point discrimination, contact detect detection, pinprick nociception, and thermal discrimination, and each one was performed before and after the surgery on days 1, 3, 7, 14, 60, and 180...
May 19, 2017: Journal of Craniofacial Surgery
https://www.readbyqxmd.com/read/28537714/enhanced-afterglow-performance-of-persistent-luminescence-implants-for-efficient-repeatable-photodynamic-therapy
#9
Wenpei Fan, Nan Lu, Can Xu, Yijing Liu, Jing Lin, Sheng Wang, Zheyu Shen, Zhen Yang, Junle Qu, Tianfu Wang, Siping Chen, Peng Huang, Xiaoyuan Chen
Persistent luminescence nanoparticles (PLNPs) have been used for bioimaging without autofluorescence background interference, but the poor afterglow performance impedes their further applications in cancer therapy. To overcome the Achilles' heel of PLNPs, herein, we report the construction of injectable persistent luminescence implants (denoted as PL implants) as a built-in excitation source for efficient repeatable photodynamic therapy (PDT). The injectable ZGC (ZnGa1.996O4:Cr0.004) PL implants were prepared by dissolving ZGC PLNPs in poly(lactic-co-glycolic acid) (PLGA)/N-methylpyrrolidone (NMP) oleosol, which demonstrated much stronger persistent luminescence (PersL) intensity and longer PersL lifetime than that of ZGC PLNPs both in vitro and in vivo...
May 24, 2017: ACS Nano
https://www.readbyqxmd.com/read/28537713/site-occupancy-preference-and-antithermal-quenching-of-the-bi-2-deep-red-emission-in-%C3%AE-ca2p2o7-bi-2
#10
Liyi Li, Jiangkun Cao, Bruno Viana, Shanhui Xu, Mingying Peng
The resistance to thermal quenching is an essential factor in evaluating the performance of luminescent materials for application in white light emitting diodes (WLEDs). In this work, we studied the site occupancy preference and thermal quenching of luminescence in β-Ca2P2O7:Bi(2+) red phosphor at low (10-300 K) and high temperatures (303-573 K). In β-Ca2P2O7, the host lattice has four different calcium sites, at which Bi(2+)dopant can be located. After comparing the change of bond energy when the Bi(2+) ions are incorporated into the four calcium sites, we found out that Bi(2+) would preferentially occupy the smaller energy variation sites Ci(2) and Ci(1) in this compound, which can be assigned to Bi(2) and Bi(1), respectively...
May 24, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28537630/nanostructure-nitride-light-emitting-diodes-via-the-talbot-effect-using-improved-colloidal-photolithography
#11
Liancheng Wang, Zhiqiang Liu, Zhi Li, Yiyun Zhang, Hongjian Li, Xiaoyan Yi, Junxi Wang, Guohong Wang, Jinmin Li
We report here a new approach of Talbot effect based colloidal photolithography for fabricating nanostructure light emitting diodes (LEDs). By employing a rigid metal nanohole array template (RDT) as the diffraction grating and a polysiloxane-based spin on dielectric (SOD) as the thickness-controllable spacer layer, various InGaN/GaN nanostructure LEDs have been fabricated. Three-dimensional finite-difference time-domain (3D-FDTD) simulations have been conducted to verify the proposed approach. Photoluminescence (PL) and time-resolved photoluminescence (TRPL) have been performed to investigate the optical properties of the obtained nanostructure LEDs...
May 24, 2017: Nanoscale
https://www.readbyqxmd.com/read/28535346/on-the-optimization-of-current-injection-in-algainp-core-shell-nanowire-light-emitting-diodes
#12
Pyry Kivisaari, Alexander Berg, Mohammad Karimi, Kristian Storm, Steven Limpert, Jani Oksanen, Lars Samuelson, Håkan Jan Pettersson, Magnus T Borgström
Core-shell nanowires offer great potential to enhance the efficiency of light-emitting diodes (LEDs) and expand the attainable wavelength range of LEDs over the whole visible spectrum. Additionally, nanowire LEDs can offer both improved light extraction and emission enhancement if the diameter of the wires is not larger than half the emission wavelength (λ/2). However, AlGaInP nanowire LEDs have so far failed to match the high efficiencies of traditional planar technologies, and the parameters limiting the efficiency remain unidentified...
May 23, 2017: Nano Letters
https://www.readbyqxmd.com/read/28535341/fully-stretchable-optoelectronic-sensors-based-on-colloidal-quantum-dots-for-sensing-photoplethysmographic-signals
#13
Tae-Ho Kim, Chang-Seok Lee, Sangwon Kim, Jaehyun Hur, Sangmin Lee, Keun Wook Shin, Young-Zoon Yoon, Moon Kee Choi, Jiwoong Yang, Dae-Hyeong Kim, Taeghwan Hyeon, Seongjun Park, Sungwoo Hwang
Flexible and stretchable optoelectronic devices can be potentially applied in displays, biosensors, biomedicine, robotics, and energy generation. The use of nanomaterials with superior optical properties such as quantum dots (QDs) is important in the realization of wearable displays and biomedical devices, but specific structural design as well as selection of materials should preferentially accompany this technology to realize stretchable forms of these devices. Here, we report stretchable optoelectronic sensors manufactured using colloidal QDs and integrated with elastomeric substrates, whose optoelectronic properties are stable under various deformations...
May 23, 2017: ACS Nano
https://www.readbyqxmd.com/read/28534904/porous-copper-graphene-heterostructures-for-cooling-of-electronic-devices
#14
Hokyun Rho, Yea Sol Jang, Sungmin Kim, Sukang Bae, Tae-Wook Kim, Dong Su Lee, Jun-Seok Ha, Sang Hyun Lee
Recently, research on micro-electronic and optoelectronic devices has been rapidly increasing. Parts and products related to these devices are becoming smaller and more integrated within circuits. As a result, the heat generated in devices has increased greatly. When excess heat is generated, important properties are affected such as efficiency and lifetime and, in severe cases, this can result in the failure of devices. Therefore, efficient cooling is required and it becomes necessary to study the heat dissipation properties of device materials...
May 23, 2017: Nanoscale
https://www.readbyqxmd.com/read/28532145/mini-photobioreactors-for-in-vivo-real-time-characterization-and-evolutionary-tuning-of-bacterial-optogenetic-circuit
#15
Hsinkai Wang, Ya-Tang Yang
The current standard protocols for characterizing the optogenetic circuit of bacterial cells using flow cytometry in light tubes and light exposure of culture plates are tedious, labor-intensive, and cumbersome. In this work, we engineer a bioreactor with working volume of ~10 mL for in vivo real-time optogenetic characterization of E. coli with a CcaS-CcaR light-sensing system. In the bioreactor, optical density measurements, reporter protein fluorescence detection, and light input stimuli are provided by four light-emitting diode sources and two photodetectors...
May 22, 2017: ACS Synthetic Biology
https://www.readbyqxmd.com/read/28527873/comparison-of-xenon-with-led-illuminant-in-difficult-and-inhalation-injury-airway-scenario-a-randomized-crossover-manikin-study
#16
Andreas Moritz, Johannes Prottengeier, Joachim Schmidt
PURPOSE: The purpose of this study was to compare the effectiveness of a Xenon halogen with a light-emitting diode (LED) laryngoscope light handle in a difficult airway scenario, as well as in an inhalation injury airway scenario that combines a difficult airway and a limited view. METHODS: We recruited forty-two anesthetists into a randomized crossover trial. Each performed tracheal intubation (TI) with a Xenon halogen and a LED light handle in the two manikin scenarios...
May 8, 2017: American Journal of Emergency Medicine
https://www.readbyqxmd.com/read/28527280/-performance-of-led-fluorescence-microscopy-for-the-detection-of-acid-fast-bacilli-from-respiratory-samples-in-peripheral-laboratories-in-argentina
#17
María Imaz, Sonia Allassia, Mónica Aranibar, Alba Gunia, Susana Poggi, Ana Togneri, Lidia Wolff, Group Of Implementation Of Fluorescence
INTRODUCTION: Light-emitting diode fluorescence microscopy (LED-FM) has been endorsed by the World Health Organization (WHO) for tuberculosis diagnosis, but its accuracy in HIV-infected patients remains controversial, and only some few studies have explored procedural factors that may affect its performance. OBJECTIVE: To evaluate the performance of LED-FM for tuberculosis diagnosis in patients with and without HIV infection using a newer, less expensive LED lamp...
June 1, 2017: Biomédica: Revista del Instituto Nacional de Salud
https://www.readbyqxmd.com/read/28524654/polyethylenimine-insulativity-dominant-charge-injection-balance-for-highly-efficient-inverted-quantum-dot-light-emitting-diodes
#18
Ke Ding, Hongting Chen, Lianwei Fan, Bo Wang, Zhi Huang, Shaoqing Zhuang, Bin Hu, Lei Wang
Quantum dot light emitting diode (QLED) with an inverted architecture always suffers charge injection imbalance and severe quantum dot charging, which degrades device performance. Blocking excess injected electrons into quantum dots (QDs) is crucial for efficient inverted QLEDs. It is found that Polyethylenimine (PEI) has two opposite effect on electron injection, one is blocking electron injection by its intrinsic insulativity and the other one is promoting electron injection by the reduced work function of ZnO/PEI...
May 19, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28523914/polymerizable-supramolecular-approach-to-highly-conductive-pedot-pss-patterns
#19
Taegeun Kim, Suryong Ha, Hyosung Choi, Kyungchan Uh, Umesha Kundapur, Sumin Park, Chan Woo Lee, Sang-Hwa Lee, Jaeyong Kim, Jong-Man Kim
Owing to its high conductivity, solution processability, mechanical flexibility and transparency, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been extensively explored for use in functional devices including solar cells, sensors, light emitting diodes and supercapacitors. The ability to fabricate patterned PEDOT:PSS on a solid substrate is of significant importance in order to develop practical applications of this conducting polymer. Herein we describe a new approach to obtain PEDOT:PSS patterns that is based on a polymerizable supramolecular concept...
May 19, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28523285/electrically-pumped-wavelength-tunable-gaas-quantum-dots-interfaced-with-rubidium-atoms
#20
Huiying Huang, Rinaldo Trotta, Yongheng Huo, Thomas Lettner, Johannes S Wildmann, Javier Martín-Sánchez, Daniel Huber, Marcus Reindl, Jiaxiang Zhang, Eugenio Zallo, Oliver G Schmidt, Armando Rastelli
We demonstrate the first wavelength-tunable electrically pumped source of nonclassical light that can emit photons with wavelength in resonance with the D2 transitions of (87)Rb atoms. The device is fabricated by integrating a novel GaAs single-quantum-dot light-emitting diode (LED) onto a piezoelectric actuator. By feeding the emitted photons into a 75 mm long cell containing warm (87)Rb vapor, we observe slow-light with a temporal delay of up to 3.4 ns. In view of the possibility of using (87)Rb atomic vapors as quantum memories, this work makes an important step toward the realization of hybrid-quantum systems for future quantum networks...
March 15, 2017: ACS Photonics
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