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Vadim V Neklyudov, Nail R Khafizov, Igor A Sedov, Ayrat M Dimiev
One of the main advantages of graphene oxide (GO) over its non-oxidized counterpart is its ability to form stable solutions in water and some organic solvents. At the same time, the nature of GO solutions is not completely understood; the existing data are scarce and controversial. Here, we demonstrate that the solubility of GO, and the stability of the as-formed solutions depend not just on the solute and solvent cohesion parameters, as commonly believed, but mostly on the chemical interactions at the GO/solvent interface...
June 21, 2017: Physical Chemistry Chemical Physics: PCCP
Mohamed E Mahmoud, Gehan M El Zokm, Aida E M Farag, Mohamed S Abdelwahab
A novel marine fungus was isolated and classified as Aspergillus flavus strain EGY11. The heat-inactivated form of isolated Aspergillus flavus was investigated and evaluated as a new eco-friendly and highly efficient biosorbent for removal of toxic heavy metals such as Cd(II), Hg(II), and Pb(II) from aqueous solutions. The SEM morphological studies of biosorbent-loaded metal ions confirmed their direct binding on the surface of heat-inactivated Aspergillus flavus. The metal biosorption capacity values were determined and optimized by the batch technique in the presence of various experimental controlling factors such as pH, contact time, biosorbent dosage, initial metal ion concentration, and coexisting species...
June 20, 2017: Environmental Science and Pollution Research International
Chao Mei, Feng Li, Jinhui Yuan, Zhe Kang, Xianting Zhang, Binbin Yan, Xinzhu Sang, Qiang Wu, Xian Zhou, Kangping Zhong, Liang Wang, Kuiru Wang, Chongxiu Yu, P K A Wai
Parabolic pulses have important applications in both basic and applied sciences, such as high power optical amplification, optical communications, all-optical signal processing, etc. The generation of parabolic similaritons in tapered hydrogenated amorphous silicon photonic wires at telecom (λ ~ 1550 nm) and mid-IR (λ ≥ 2100 nm) wavelengths is demonstrated and analyzed. The self-similar theory of parabolic pulse generation in passive waveguides with increasing nonlinearity is presented. A generalized nonlinear Schrödinger equation is used to describe the coupled dynamics of optical field in the tapered hydrogenated amorphous silicon photonic wires with either decreasing dispersion or increasing nonlinearity...
June 19, 2017: Scientific Reports
Hyeongrak Choi, Mikkel Heuck, Dirk Englund
We propose a photonic crystal nanocavity design with self-similar electromagnetic boundary conditions, achieving ultrasmall mode volume (V_{eff}). The electric energy density of a cavity mode can be maximized in the air or dielectric region, depending on the choice of boundary conditions. We illustrate the design concept with a silicon-air one-dimensional photon crystal cavity that reaches an ultrasmall mode volume of V_{eff}∼7.01×10^{-5}λ^{3} at λ∼1550  nm. We show that the extreme light concentration in our design can enable ultrastrong Kerr nonlinearities, even at the single-photon level...
June 2, 2017: Physical Review Letters
Mitra Rashidian, Victor Minichiello, Synnove F Knutsen, Mark Ghamsary
Background: Although obtaining sexual history from patients is essential, the attitudes of physicians can become a barrier to sexual health care. Iranian-American physicians may face particular challenges because talking about sexuality is considered a taboo within their culture. Our study examined these physicians' attitudes when taking a sexual history from their patients. Methods: In 2013, a self-administrated questionnaire was sent to 1550 Iranian-American physicians in California, USA. Using factor analysis, the principal components approach with a Varimax rotation was used on a set of 12-item questions (five-point Likert scales) to detect latent factors that explain attitudes affecting sexual history taking...
June 16, 2017: Sexual Health
Krishna C Balram, Marcelo I Davanço, B Robert Ilic, Ji-Hoon Kyhm, Jin Dong Song, Kartik Srinivasan
Acoustic wave devices provide a promising chip-scale platform for efficiently coupling radio frequency (RF) and optical fields. Here, we use an integrated piezo-optomechanical circuit platform that exploits both the piezoelectric and photoelastic coupling mechanisms to link 2.4 GHz RF waves to 194 THz (1550 nm) optical waves, through coupling to propagating and localized 2.4 GHz acoustic waves. We demonstrate acousto-optic modulation, resonant in both the optical and mechanical domains, in which waveforms encoded on the RF carrier are mapped to the optical field...
February 2017: Physical Review Applied
Hidetaka Terasawa, Freddy Tan, Okihiro Sugihara, Akari Kawasaki, Daisuke Inoue, Tatsuya Yamashita, Manabu Kagami, Olivier Maury, Yann Bretonnière, Chantal Andraud
Light-induced self-written (LISW) optical waveguides were fabricated for the first time, to the best of our knowledge, using a photopolymerizable resin system formed by 1550 nm pulse laser light. A two-photon absorption (TPA) chromophore with a TPA cross section of several hundred Goeppert-Mayer (GM) at 1550 nm was used. Furthermore, the optical interconnection between a single-mode fiber and a fiber Bragg grating was demonstrated by the present technique, using one-way irradiation of 1550 nm laser light through the single-mode fiber...
June 1, 2017: Optics Letters
Florian Denis-le Coarer, Ana Quirce, Ángel Valle, Luis Pesquera, Marc Sciamanna, Hugo Thienpont, Krassimir Panajotov
We report an experimental study of the polarization nonlinear dynamics in a 1550 nm single-mode vertical-cavity surface-emitting laser (VCSEL) subject to parallel optical injection. Experimentally measured stability maps identifying regions of different nonlinear dynamics for various values of bias current are reported. We show that VCSELs with more than a 35 dB polarization mode suppression ratio can have rich nonlinear dynamics in both linear polarizations, including periodic and chaotic behaviors appearing simultaneously in both polarization modes...
June 1, 2017: Optics Letters
Parinaz Aleahmad, Mercedeh Khajavikhan, Demetrios Christodoulides, Patrick LiKamWa
On-chip photonic networks hold great promise for enabling next-generation high speed computation and communication systems. It is currently envisioned that future integrated photonic networks will be capable of processing dense digital information on a single monolithic platform by involving a multitude of optical components ranging from lasers to modulators, to routers, interconnects and detectors. Among the possible functionalities to be incorporated in such arrangements is the ability to route information in a unidirectional way among N-ports - a capability typically afforded through the use of optical circulators...
May 18, 2017: Scientific Reports
Reza Khazaeinezhad, Meena Siddiqui, Benjamin J Vakoc
We demonstrate a novel high-speed and broadband laser architecture based on stretched pulse active mode locking that provides a wavelength-swept and wavelength-stepped output. The laser utilizes a single intracavity 8.3 meter chirped fiber Bragg grating to generate positive and negative dispersion, and can be operated with or without an intracavity fixed Fabry-Perot etalon to generate wavelength-swept and wavelength-stepped (frequency comb) outputs, respectively. Using a four-path delay line at the output, we achieved 16...
May 15, 2017: Optics Letters
Honghui Sun, Tian Jiang, Yunyi Zang, Xin Zheng, Yan Gong, Yong Yan, Zhongjie Xu, Yu Liu, Liang Fang, Xiang'ai Cheng, Ke He
Topological insulators (TIs) are new states of quantum matter in which the spin-momentum-locked surface states reside in the bulk insulating gap and have triggered extensive investigations on fundamental properties and potential applications. Herein, we report scalable, broadband photovoltaic detectors based on the topological insulator Sb2Te3/strontium titanate (STO) heterostructure. Large-scale (2 mm × 5 mm), high crystalline quality p-type Sb2Te3 films were fabricated on an n-type STO substrate by the molecular beam epitaxy (MBE) method...
May 12, 2017: Nanoscale
Lijun Huang, Hai Yan, Xiaochuan Xu, Swapnajit Chakravarty, Naimei Tang, Huiping Tian, Ray T Chen
Compared to the conventional strip waveguide microring resonators, subwavelength grating (SWG) waveguide microring resonators have better sensitivity and lower detection limit due to the enhanced photon-analyte interaction. As sensors, especially biosensors, are usually used in absorptive ambient environment, it is very challenging to further improve the detection limit of the SWG ring resonator by simply increasing the sensitivity. The high sensitivity resulted from larger mode-analyte overlap also brings significant absorption loss, which deteriorates the quality factor of the resonator...
May 1, 2017: Optics Express
Shen Xiang, Hu Xiongwei, Yang Luyun, Dai Nengli, Wu Jianjun, Zhang Fangfang, Peng Jingang, Li Haiqing, Li Jinyan
We have demonstrated a helical long-period grating (HLPG) manufactured from multicore fiber (MCF) combined with twist and CO<sub>2</sub>-laser heating technology. The MCF we used behaves as a kind of single mode fiber. The nineteen cores of MCF are distributed hexagonally which make the helical structure only exist in core area after heating and twisting. There are several strong couplings between the core and cladding modes at different wavelengths when the grating pitch was 900 µm. The extinction ratio of the main coupling reached 20 dB at 1550 nm...
May 1, 2017: Optics Express
Christoph A Riedel, Kai Sun, Otto L Muskens, C H de Groot
The interest in plasmonic electro-optical modulators with nanoscale footprint and ultrafast low-energy performance has generated a demand for precise multiphysics modeling of the electrical and optical properties of plasmonic nanostructures. We perform combined simulations that account for the interaction of highly confined nearfields with charge accumulation and depletion on the nanoscale. Validation of our numerical model is done by comparison to a recently published reflective meta-absorber. The simulations show excellent agreement to the experimental mid-infrared data...
May 1, 2017: Optics Express
Riccardo Marchetti, Valerio Vitali, Cosimo Lacava, Ilaria Cristiani, Benoit Charbonnier, Viviane Muffato, Maryse Fournier, Paolo Minzioni
We report on the experimental characterization, in the telecom C-band, of group-velocity dispersion (D) in 100-nm high rectangular strip waveguides realized by silicon-on-insulator technology. We compare the experimental results with numerical predictions, showing that 100-nm high waveguides exhibit normal dispersion and that the absolute value of the dispersion coefficient D decreases as the waveguide width is increased. D at 1550 nm varies from -8130 to -3900 ps/(nm·km) by increasing the waveguide width from 500 to 800 nm...
May 1, 2017: Optics Express
Yongsoo Lee, Wooram Kim
The application of laser treatments beginning on the day of stitch removal has been demonstrated to improve scar quality. However, there are few guidelines for the treatment of immature scars (ISs), which are defined as "scars whose features are not yet expressed." The purpose of this study was to extract information about early combination laser treatment (CLT) beyond what is currently known by analyzing 33 pairs of pre-treatment and post-treatment photographs of ISs. Two hundred fifty medical records of patients with scars were reviewed, and 33 scars were included in the study...
May 2, 2017: Lasers in Medical Science
Malcolm W Clark, Laure M Despland, Neal J Lake, Lachlan H Yee, Manuela Anstoetz, Elisabeth Arif, Jeffery F Parr, Philip Doumit
Sugarcane bagasse ash re-utilisation has been advocated as a silica-rich feed for zeolites, pozzolans in cements and concretes, and geopolymers. However, many papers report variable success with the incorporation of such materials in these products as the ash can be inconsistent in nature. Therefore, understanding what variables affect the ash quality in real mills and understanding the processes to characterise ashes is critical in predicting successful ash waste utilisation. This paper investigated sugarcane bagasse ash from three sugar mills (Northern NSW, Australia) where two are used for the co-generation of electricity...
April 2017: Heliyon
O A Lukianova, V Yu Novikov, A A Parkhomenko, V V Sirota, V V Krasilnikov
The microstructure and phase composition of the high-content Al2O3-Y2O3-doped spark plasma-sintered silicon nitride were investigated. Fully dense silicon nitride ceramics with a typical α-Si3N4 equiaxed structure with average grain size from 200 to 530 nm, high elastic modulus of 288 GPa, and high hardness of 2038 HV were spark plasma sintered (SPSed) at 1550 °C. Silicon nitride with elongated β-Si3N4 grains, higher hardness of 1800 HV, density of 3.25 g/cm(3), and Young's modulus 300 GPa SPSed at 1650 °C was also reviewed...
December 2017: Nanoscale Research Letters
Subramaniam Kuppuswamy, Joshua D Wofford, Chris Joseph, Zhu-Lin Xie, Azim K Ali, Vincent M Lynch, Paul A Lindahl, Michael J Rose
The syntheses, interconversions, and spectroscopic properties of a set of iron carbonyl clusters containing an interstitial carbide are reported. This includes the low temperature X-ray structures of the six-iron clusters (Y)2[Fe6(μ6-C)(μ2-CO)4(CO)12] (1a-c; where Y = NMe4, NEt4, PPh4); the five-iron cluster [Fe5(μ5-C)(CO)15] (3); and the novel formulation of the five-iron cluster (NMe4)2[Fe5(μ5-C)(μ2-CO)(CO)13] (4). Also included in this set is the novel charge-neutral cluster, [Fe6(μ6-C)(CO)18] (2), for which we were unable to obtain a crystallographic structure...
April 25, 2017: Inorganic Chemistry
M A Eftekhar, L G Wright, M S Mills, M Kolesik, R Amezcua Correa, F W Wise, D N Christodoulides
We demonstrate that the pump's spatial input profile can provide additional degrees of freedom in tailoring at will the nonlinear dynamics and the ensuing spectral content of supercontinuum generation in highly multimoded optical fibers. Experiments and simulations carried out at 1550 nm indicate that the modal composition of the input beam can substantially alter the soliton fission process as well as the resulting Raman and dispersive wave generation that eventually lead to supercontinuum in such a multimode environment...
April 17, 2017: Optics Express
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