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https://www.readbyqxmd.com/read/28454481/aln-surface-passivation-of-gan-based-high-electron-mobility-transistors-by-plasma-enhanced-atomic-layer-deposition
#1
An-Jye Tzou, Kuo-Hsiung Chu, I-Feng Lin, Erik Østreng, Yung-Sheng Fang, Xiao-Peng Wu, Bo-Wei Wu, Chang-Hong Shen, Jia-Ming Shieh, Wen-Kuan Yeh, Chun-Yen Chang, Hao-Chung Kuo
We report a low current collapse GaN-based high electron mobility transistor (HEMT) with an excellent thermal stability at 150 °C. The AlN was grown by N2-based plasma enhanced atomic layer deposition (PEALD) and shown a refractive index of 1.94 at 633 nm of wavelength. Prior to deposit AlN on III-nitrides, the H2/NH3 plasma pre-treatment led to remove the native gallium oxide. The X-ray photoelectron spectroscopy (XPS) spectroscopy confirmed that the native oxide can be effectively decomposed by hydrogen plasma...
December 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28454179/simple-effective-medium-approximation-with-rayleigh-scattering
#2
Ashfaqul Anwar Siraji, Yang Zhao
We present a simple analytical effective medium approximation (EMA) that can account for finite-sized and interacting inclusions in the Rayleigh scattering regime. The polarizability of an individual inclusion is calculated using the Mie solution and net polarizability is formed, leading to effective parameters. The Mie coefficients are expanded into polynomials and curtailed to the sixth order, which is accurate in the Rayleigh regime. Results obtained using the developed models are compared with experimental results and existing EMAs...
May 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/28454172/are-optical-fibers-really-uniform-measurement-of-refractive-index-on-a-centimeter-scale
#3
Sébastien Loranger, Raman Kashyap
Many applications of optical fiber, such as specialized fiber Bragg gratings (FBGs), require high uniformity of a fiber's refractive index (RI) along its length. We show here that the mode effective index of most fibers is not constant, even on a short length scale. To help improve fiber manufacturing and selection, we demonstrate a technique for characterizing a meter length single-mode optical fiber's effective RI over a centimeter scale with a precision of 3×10<sup>-6</sup> RI units (RIUs) and an absolute accuracy of 2×10<sup>-4</sup> RIU...
May 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/28454141/incoherent-optical-modulation-of-graphene-based-on-an-in-line-fiber-mach-zehnder-interferometer
#4
Cong Gao, Lei Gao, Tao Zhu, Guolu Yin
We investigated the incoherent optical modulation of graphene based on an in-line fiber Mach-Zehnder interferometer fabricated by offset splicing of a D-shaped fiber and single-mode fibers. The D-shaped flat surface was coated with a single-layer graphene whose refractive index can be modulated by an external laser. With a backward pump-probe setup, we found that the incoherent optical modulation occurred independently of the wavelength difference between the pump and probe lasers, supporting the theoretical analysis that the incoherent optical modulation is mainly contributed by the carrier-phonon process of graphene...
May 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/28454135/fiber-surface-bragg-grating-waveguide-for-refractive-index-measurements
#5
Chupao Lin, Changrui Liao, Jia Wang, Jun He, Ying Wang, Zhengyong Li, Tianhang Yang, Feng Zhu, Kaiming Yang, Zhe Zhang, Yiping Wang
A fiber surface Bragg grating waveguide (BGW) fabricated in the surface of single-mode fiber by direct femtosecond laser inscription is demonstrated and successfully applied for refractive index (RI) measurements. Prior to laser inscription of the fiber surface BGW, an X-coupler is first inscribed across the fiber core to couple light from the core to the fiber surface. The light transmitted in the fiber surface BGW efficiently interacts with the surrounding medium due to a strong evanescent field, and obtains an acceptable RI sensitivity approaching ∼16  nm/RIU...
May 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/28454129/photostability-of-pulsed-laser-deposited-as-sub-x-sub-te-sub-100-x-sub-x-40-50-60-amorphous-thin-films
#6
Petra Hawlová, Marek Bouška, Virginie Nazabal, Emeline Baudet, Zdeněk Černošek, Petr Němec
As<sub>x</sub>Te<sub>100-x</sub> amorphous thin films were fabricated by a pulsed laser deposition technique with the aim of finding photostable layers in as-deposited but preferably in relaxed (annealed) state. Photostability was studied in terms of the films' stability of refractive index and bandgap under near-bandgap light irradiation. As<sub>40</sub>Te<sub>60</sub> and As<sub>50</sub>Te<sub>50</sub> layers were found to be photostable in both as-deposited as well as relaxed states...
May 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/28454022/quantitative-analysis-of-adsorptive-interactions-of-ionic-and-neutral-pharmaceuticals-and-other-chemicals-with-the-surface-of-escherichia-coli-cells-in-aquatic-environment
#7
Chul-Woong Cho, Jeong-Soo Park, Yufeng Zhao, Yeoung-Sang Yun
Since Escherichia coli is ubiquitous in nature and has been applied to biological, chemical, and environmental processes, molecular-level understanding of adsorptive interactions between chemicals and the bacterial surface is of great importance. To characterise the adsorption properties of the surface of E. coli cells in aquatic environment, the binding affinities (log Kd) of calibration compounds were experimentally measured, and then based on the values and numerically well-defined molecular interaction forces, i...
April 25, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28453957/a-magnetic-droplet-vaporization-approach-using-perfluorohexane-encapsulated-magnetic-mesoporous-particles-for-ultrasound-imaging-and-tumor-ablation
#8
Zhaogang Teng, Ronghui Wang, Yang Zhou, Michael Kolios, Yanjie Wang, Nan Zhang, Zhigang Wang, Yuanyi Zheng, Guangming Lu
Phase change agents consisting of low boiling point perfluorocarbon (PFC) compounds have attracted increasing attention for ultrasound contrast-enhanced imaging and tumor therapy. However, the refraction, acoustic shadowing, reverberation, or limited penetration depth hamper their practical applications through previously reported acoustic droplet vaporization (ADV) or optical droplet vaporization (ODV) technique. Herein, we demonstrate a magnetic droplet vaporization (MDV) approach by loading perflurohexane (PFH) in magnetic mesoporous particles with a hollow space to carry out ultrasound imaging and tumor ablation...
April 15, 2017: Biomaterials
https://www.readbyqxmd.com/read/28448294/macular-ganglion-cell-and-retinal-nerve-fiber-layer-thickness-in-children-with-refractive-errors-an-optical-coherence-tomography-study
#9
Jody P Goh, Victor Koh, Yiong Huak Chan, Cheryl Ngo
PURPOSE: To study the distribution of macular ganglion cell-inner plexiform layer (GC-IPL) thickness and peripapillary retinal nerve fiber layer (RNFL) thickness in children with refractive errors. MATERIALS AND METHODS: Two hundred forty-three healthy eyes from 139 children with refractive error ranging from -10.00 to +5.00 D were recruited from the National University Hospital Eye Surgery outpatient clinic. After a comprehensive ocular examination, refraction, and axial length (AL) measurement (IOLMaster), macular GC-IPL and RNFL thickness values were obtained with a spectral domain Cirrus high definition optical coherence tomography system (Carl Zeiss Meditec Inc...
April 26, 2017: Journal of Glaucoma
https://www.readbyqxmd.com/read/28447481/a-correction-method-for-attenuated-total-reflection-far-ultraviolet-spectra-via-the-use-of-charge-transfer-to-solvent-band-intensities-of-iodide-in-the-ultraviolet-region
#10
Akifumi Ikehata, Takeyoshi Goto, Yusuke Morisawa
Attenuated total reflection (ATR) spectra, which are often used in IR analysis, can be transformed into extinction and refraction spectra by Kramers-Kronig transformation (KKT) with Fresnel equations. However, it is often difficult to obtain correct optical indices due to the inherent instrumental functions. This paper proposes a simple practical method for correction of KKT with two parameters, which include all the effects of the instrumental function. In order to obtain the parameters of the instrumental function, absorption ratios of charge transfer to solvent (CTTS) transitions of aqueous iodide ions observed at 195 nm and 230 nm were used as a standard...
January 1, 2017: Applied Spectroscopy
https://www.readbyqxmd.com/read/28445315/the-effect-of-timolol-0-5-on-the-correction-of-myopic-regression-after-lasik
#11
Hong Qi, Caifeng Gao, Yaxin Li, Xue Feng, Miao Wang, Yu Zhang, Yueguo Chen
BACKGROUD: Postlaser in situ keratomileusis (post-LASIK) refractive regression is defined as the gradual, partial, or total loss of initial correction that limits the predictability, efficiency, and long-term stability of LASIK. Our study assesses the effect of Timolol 0.5% on the correction of myopic regression after LASIK. METHODS: This prospective, randomized, controlled study included 62 eyes of 62 patients with myopic regression of -1.18 ± 0.86 diopters (D) after myopic LASIK...
April 2017: Medicine (Baltimore)
https://www.readbyqxmd.com/read/28445204/pediatric-refractive-surgery
#12
Erin D Stahl
PURPOSE OF REVIEW: Refractive surgery procedures have been performed on children since the early 1980s. This article will review this history as well as current thoughts on treating children with large refractive errors. RECENT FINDINGS: Pediatric refractive surgery has developed slowly as very few children fit the criteria for treatment. For this reason, practice patterns are varied and publications are rare. Publications in recent years have focused on intraocular procedures over laser refractive surgery...
April 25, 2017: Current Opinion in Ophthalmology
https://www.readbyqxmd.com/read/28445203/considerations-for-refractive-surgery-in-the-glaucoma-patient
#13
Meleha Ahmad, Isaac Chocron, Anurag Shrivastava
PURPOSE OF REVIEW: Given the popularity of keratorefractive surgery, and an aging populous of patients who have undergone these procedures, there is an increasing need for updated management protocols. This is particularly relevant for patients with chronic progressive diseases such as glaucoma, due to the variety of related diagnostic and management challenges inherent to these diseases. Here, we will review the current literature to provide an update on the management of patients with glaucoma who are undergoing, or have had laser ablative refractive surgery...
April 25, 2017: Current Opinion in Ophthalmology
https://www.readbyqxmd.com/read/28445192/one-year-clinical-outcomes-of-a-corneal-inlay-for-presbyopia
#14
Sandra M C Beer, Rodrigo Santos, Eliane M Nakano, Flavio Hirai, Enrico J Nitschke, Claudia Francesconi, Mauro Campos
PURPOSE: To report the results of a 1-year follow-up analysis of the safety and efficacy of the Flexivue Microlens corneal inlay. METHODS: The Flexivue Microlens corneal inlay was implanted in the nondominant eye of patients with emmetropic presbyopia (a spherical equivalent of -0.5 to 1.00 diopter) after the creation of a 300-μm deep stromal pocket, using a femtosecond laser. The patients were followed up according to a clinical protocol involving refraction, anterior segment imaging analysis (Oculyzer), and optical quality analysis (OPD-Scan)...
April 25, 2017: Cornea
https://www.readbyqxmd.com/read/28442787/the-upper-limit-of-the-in-plane-spin-splitting-of-gaussian-beam-reflected-from-a-glass-air-interface
#15
Wenguo Zhu, Jianhui Yu, Heyuan Guan, Huihui Lu, Jieyuan Tang, Jun Zhang, Yunhan Luo, Zhe Chen
Optical spin splitting has a promising prospect in quantum information and precision metrology. Since it is typically small, many efforts have been devoted to its enhancement. However, the upper limit of optical spin splitting remains uninvestigated. Here, we investigate systematically the in-plane spin splitting of a Gaussian beam reflected from a glass-air interface and find that the spin splitting can be enhanced in three different incident angular ranges: around the Brewster angle, slightly smaller than and larger than the critical angle for total reflection...
April 25, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28442706/nitric-oxide-no-mediates-the-inhibition-of-form-deprivation-myopia-by-atropine-in-chicks
#16
Brittany J Carr, William K Stell
Myopia is the most common childhood refractive disorder. Atropine inhibits myopia progression, but its mechanism is unknown. Here, we show that myopia-prevention by atropine requires production of nitric oxide (NO). Form-deprivation myopia (FDM) was induced in week-old chicks by diffusers over the right eye (OD); the left eye (OS) remained ungoggled. On post-goggling days 1, 3, and 5, OD received intravitreally 20 µL of phosphate-buffered saline (vehicle), or vehicle plus: NO source: L-arginine (L-Arg, 60-6,000 nmol) or sodium nitroprusside (SNP, 10-1,000 nmol); atropine (240 nmol); NO inhibitors: L-NIO or L-NMMA (6 nmol); negative controls: D-Arg (10 µmol) or D-NMMA (6 nmol); or atropine plus L-NIO, L-NMMA, or D-NMMA; OS received vehicle...
December 5, 2016: Scientific Reports
https://www.readbyqxmd.com/read/28441321/a-cost-effective-relative-humidity-sensor-based-on-side-coupling-induction-technology
#17
Yingzi Zhang, Yulong Hou, Wenyi Liu, Huixin Zhang, Yanjun Zhang, Zhidong Zhang, Jing Guo, Jia Liu, Liang Zhang, Qiu-Lin Tan
A intensity-modulated optical fiber relative humidity (RH) sensor based on the side coupling induction technology (SCIT) is presented and experimentally demonstrated. The agarose gel and the twisted macro-bend coupling structure are first combined for RH sensing applications. The refractive index (RI) of the agarose gel increases with the increase of the RH and is in linear proportion from 20 to 80%RH. The side coupling power, which changes directly with the RI of the agarose gel, can strip the source noise from the sensor signal and improve the signal to noise ratio substantially...
April 25, 2017: Sensors
https://www.readbyqxmd.com/read/28440826/realization-of-multiphoton-lasing-from-carbon-nanodot-microcavities
#18
Wenfei Zhang, Yiqun Ni, Xuhui Xu, Wei Lu, Pengpeng Ren, Peiguang Yan, Chun Kit Siu, Shuangchen Ruan, Siu Fung Yu
The use of organosilane chains to link carbon nanodots (CDs) through organosilane surface functional groups is proposed to improve the efficiency of multiphoton absorption. As a result, a large absorption coefficient of 1.16 × 10(-6) cm(5) per GW(3) is obtained and four-photon luminescence under 1900 nm excitation is observed from the CDs at room temperature. Furthermore, a CD laser, which demonstrates random lasing under three-photon (i.e. 1400 nm) excitation, can be realized by sandwiching a CD film between a quartz substrate and a dielectric mirror...
April 25, 2017: Nanoscale
https://www.readbyqxmd.com/read/28439975/scleral-changes-with-accommodation
#19
Alejandra Consejo, Hema Radhakrishnan, D Robert Iskander
PURPOSE: To assess whether the sclera changes its shape during accommodation, quantify those changes and ascertain whether they depend on age and refractive power. METHODS: Twenty-two subjects, aged between 19 and 84 years old were recruited for the study. Young subjects were grouped according to their refractive power as emmetropes (seven subjects) and myopes (seven subjects). Data were obtained with a height corneo-scleral topographer (Eye Surface Profiler) with coverage area far beyond the limbus...
May 2017: Ophthalmic & Physiological Optics: the Journal of the British College of Ophthalmic Opticians (Optometrists)
https://www.readbyqxmd.com/read/28439427/double-aorta-artifact-in-sonography-a-diagnostic-challenge
#20
REVIEW
Robert Hadzik, Przemysław Bombiński, Michał Brzewski
The double aorta artifact was described and studied thoroughly twenty-five years ago. Despite this, it is still not commonly known today and can cause diagnostic difficulty. Total aortic duplication can be considered an anatomic defect whilst partial duplication mimics aortic dissection. In the literature, this artifact has been compared with a very rare anomaly, i.e. the occurrence of two aortas in one patient. Currently, however, the differentiation of this artifact from abdominal aortic dissection seems to be of greater significance...
March 2017: Journal of Ultrasonography
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