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Giuseppe Riva
No abstract text is available yet for this article.
September 2017: Cyberpsychology, Behavior and Social Networking
Manoj Kumar, A Vijayakumar, Joseph Rosen
We present a lensless, interferenceless incoherent digital holography technique based on the principle of coded aperture correlation holography. The acquired digital hologram by this technique contains a three-dimensional image of some observed scene. Light diffracted by a point object (pinhole) is modulated using a random-like coded phase mask (CPM) and the intensity pattern is recorded and composed as a point spread hologram (PSH). A library of PSHs is created using the same CPM by moving the pinhole to all possible axial locations...
September 14, 2017: Scientific Reports
Mohammad Hadi Tavakoli Dastjerdi, Elisabetta Maria Fiordaliso, Egor Leshchenko, Azadeh Akhtari-Zavareh, Takeshi Kasama, Martin Aagesen, Vladimir G Dubrovskii, Ray Robert LaPierre
A new dopant incorporation mechanism in Ga-assisted GaAs nanowires grown by molecular beam epitaxy is reported. Off-axis electron holography revealed that p-type Be dopants introduced in situ during molecular beam epitaxy growth of the nanowires were distributed inhomogeneously in the nanowire cross-section, perpendicular to the growth direction. The active dopants showed a remarkable azimuthal distribution along the (111)B flat top of the nanowires, which is attributed to preferred incorporation along three-fold symmetric truncated facets under the Ga droplet...
September 13, 2017: Nano Letters
Yi-Chieh Lai, Tzu Cheng Kuang, Bo Han Cheng, Yung-Chiang Lan, Din Ping Tsai
An electron bunch passing through a periodic metal grating can emit Smith-Purcell radiation (SPR). Recently, it has been found that SPR can be locked and enhanced at some emission wavelength and angle by excitation of surface plasmon (SP) on the metal substrate. In this work, the generation of a convergent light beam via using the SP-locked SPR is proposed and investigated by computer simulations. The proposed structure is composed of an insulator-metal-insulator (IMI) substrate with chirped gratings on the substrate...
September 11, 2017: Scientific Reports
Alok Kumar Singh, Giancarlo Pedrini, Mitsuo Takeda, Wolfgang Osten
Scattering media have always been looked upon as an obstacle in imaging. Various methods, ranging from holography to phase compensation as well as to correlation techniques, have been proposed to cope with this obstacle. We, on the other hand, have a different understanding about the role of the diffusing media. In this paper we propose and demonstrate a 'scatter-plate microscope' that utilizes the diffusing property of the random medium for imaging micro structures with diffraction-limited resolution. The ubiquitous property of the speckle patterns permits to exploit the scattering medium as an ultra-thin lensless microscope objective with a variable focal length and a large working distance...
September 6, 2017: Scientific Reports
Muhammad Waqas Khalid, Rajib Ahmed, Ali K Yetisen, Bader AlQattan, Haider Butt
The optical phase conjugation (OPC) through photonic nanostructures in coherent optics involves the utilization of a nonlinear optical mechanism through real-time processing of electromagnetic fields. Their applications include spectroscopy, optical tomography, wavefront sensing, and imaging. The development of functional and personalized holographic devices in the visible and near-infrared spectrum can be improved by introducing cost-effective, rapid, and high-throughput fabrication techniques and low-cost recording media...
September 6, 2017: Scientific Reports
Takashi Kakue, Yutaka Endo, Takashi Nishitsuji, Tomoyoshi Shimobaba, Nobuyuki Masuda, Tomoyoshi Ito
Digital holography allows production of high-speed three-dimensional images at rates over 100,000 frames per second; however, simultaneously obtaining suitable performance and levels of accuracy using digital holography is difficult. This problem prevents high-speed three-dimensional imaging from being used for vibrometry. In this paper, we propose and test a digital holography method that can produce vibration measurements. The method is based on single-shot phase-shifting interferometry. Herein, we imaged the surface of a loudspeaker diaphragm and measured its displacement due to the vibrations produced by a frequency sweep signal...
September 5, 2017: Scientific Reports
M Brunel, G Demange, M Fromager, M Talbi, H Zapolsky, R Patte, K Aït Ameur, J Jacquot-Kielar, S Coetmellec, G Gréhan, B Quevreux
Airborne characterization of ice crystals has important applications. The extreme difficulty of realizing in situ tests requires the development of a complete instrumentation in the laboratory. Such an installation should enable design, development, test, and calibration of instruments in conditions as close as possible to real ones. We present a set of numerical and experimental tools that have been developed to realize ice crystal sensors based on interferometric particle imaging. The set of tools covers the development of complementary simulators for crystal growth and interferometric particle imaging predictions, experimental generation of "programmable" ice crystals, and instrumentation of a freezing column where different techniques as in-focus imaging, out-of-focus imaging, and digital in-line holography can be combined simultaneously for test and calibration...
August 2017: Review of Scientific Instruments
Thibaut Le Magueresse, Jean-Hugh Thomas, Jérôme Antoni, Sébastien Paillasseur
Real-time near-field acoustic holography (RT-NAH) is used to recover non-stationary sound sources using a planar microphone array. Direct propagation is described by the convolution of the wavenumber spectrum of the source under study with a known impulse response. The deconvolution operation is achieved by a singular value decomposition of the propagator and Tikhonov regularization is performed to stabilize the solution. The inverse problem has an innate ill-posed characteristic, and the regularization process is the key factor in obtaining acceptable results...
August 2017: Journal of the Acoustical Society of America
Jørgen Hald
Measured cross-spectral matrices (CSMs) from a microphone array will in some cases be contaminated by severe incoherent noise signals in the individual channels. A typical example is flow noise generated in the individual microphones when measuring in a wind tunnel. Assuming stationary signals and performing long-time averaging, the contamination will be concentrated on the CSM diagonal. When the CSM is used for traditional frequency-domain beamforming, diagonal removal (DR) will avoid use of the diagonal. DR is effective at suppressing the contamination effects, but it also has some side effects...
August 2017: Journal of the Acoustical Society of America
Matthew J Berg, Yuli W Heinson, Osku Kemppinen, Stephen Holler
Coarse mode atmospheric aerosol particles are abundant in agricultural, desert, and urban environments. Accurate characterisation of these particles' morphology is an important need in scientific and applied contexts, especially to advance our understanding for how such aerosols influence solar radiative forcing of the atmosphere. Elastic light scattering is a standard method to study aerosol particles in a contact-free manner, wherein measured scattering patterns are interpreted to infer particle morphology...
August 24, 2017: Scientific Reports
Alexandra D Furasova, Vladimir Ivanovski, Alexandr V Yakovlev, Valentine A Milichko, Vladimir V Vinogradov, Alexandr V Vinogradov
We have demonstrated for the first time an inkjet fabrication of highly efficient luminescent structures based on Eu-doped ZrO2 nanocrystals (3.4 ± 0.3 nm), with a refractive index close to the one of the bulk materials. The nanoparticles were synthesised using a nonhydrolytic method in benzyl alcohol where the particles were post treated using acetic acid, leading to the formation of a stable colloid. It was shown that the non-polar methyl group of the acetic acid is responsible for its penetration through the hydrophobic layer all the way through to the surface of the ZrO2, leading to the cleavage of the Zr-OCH2C6H5 bond and the formation of surface acetate species and a concomitant decomposition of the zirconia superlattice...
September 14, 2017: Nanoscale
Kouichi Hayashi, Kenji Ohoyama, Naohisa Happo, Tomohiro Matsushita, Shinya Hosokawa, Masahide Harada, Yasuhiro Inamura, Hiroaki Nitani, Toetsu Shishido, Kunio Yubuta
Local structures around impurities in solids provide important information for understanding the mechanisms of material functions, because most of them are controlled by dopants. For this purpose, the x-ray absorption fine structure method, which provides radial distribution functions around specific elements, is most widely used. However, a similar method using neutron techniques has not yet been developed. If one can establish a method of local structural analysis with neutrons, then a new frontier of materials science can be explored owing to the specific nature of neutron scattering-that is, its high sensitivity to light elements and magnetic moments...
August 2017: Science Advances
Adam D Maxwell, Petr V Yuldashev, Wayne Kreider, Tatiana D Khokhlova, George R Schade, Timothy L Hall, Oleg A Sapozhnikov, Michael R Bailey, Vera A Khokhlova
Boiling histotripsy is a method of focused ultrasound surgery that noninvasively applies millisecond-length pulses with high-amplitude shock fronts to generate liquefied lesions in tissue. Such a technique requires unique outputs compared to a focused ultrasound thermal therapy apparatus, particularly to achieve high in situ pressure levels through intervening tissue. This article describes the design and characterization of a system capable of producing the necessary pressure to transcutaneously administer boiling histotripsy therapy through clinically relevant overlying tissue paths using pulses with duration up to 10 ms...
August 14, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Eduardo Ortega, Jesús Cantu-Valle, Germán Plascencia-Villa, Sandra Vergara, Fernando Mendoza-Santoyo, Alejandra Londono-Calderon, Ulises Santiago, Arturo Ponce
In the current work, irregular morphology of Staphylococcus aureus bacteria has been visualized by phase retrieval employing off-axis electron holography (EH) and 3D reconstruction electron tomography using high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM). Bacteria interacting with gold nanoparticles (AuNP) acquired a shrunken or irregular shape due to air dehydration processing. STEM imaging shows the attachment of AuNP on the surface of cells and suggests an irregular 3D morphology of the specimen...
August 11, 2017: Microscopy Research and Technique
Vijay Bhooshan Kumar, Amit Kumar Sahu, Abu S M Mohsin, Xiangping Li, Aharon Gedanken
In this manuscript, we report the refractive-index (RI) modulation of various concentrations of nitrogen-doped carbon dots (N@C-dots) embedded in poly(vinyl alcohol) (PVA) polymer. The dispersion and size distribution of N@C-dots embedded within PVA have been investigated using electron microscopy. The RI of PVA-N@C-dots can be enhanced by increasing the doping concentration of highly fluorescent C-dots (quantum yield 44%). This is demonstrated using ultraviolet-visible (UV-visible), photoluminscence, Raman, and Fourier transform infrared (FTIR) spectroscopy measurements...
August 30, 2017: ACS Applied Materials & Interfaces
Tatiana Latychevskaia, Flavio Wicki, Conrad Escher, Hans-Werner Fink
While imaging individual atoms can routinely be achieved in high resolution transmission electron microscopy, visualizing the potential distribution of individually charged adsorbates leading to a phase shift of the probing electron wave is still a challenging task. Low-energy electrons (30 - 250 eV) are sensitive to localized potential gradients. We employed low-energy electron holography to acquire in-line holograms of individual charged impurities on free-standing graphene. By applying an iterative phase retrieval reconstruction routine we recover the potential distribution of the localized charged impurities present on free-standing graphene...
July 29, 2017: Ultramicroscopy
Yohsuke T Fukai, Kazumasa A Takeuchi
We study the (1+1)-dimensional Kardar-Parisi-Zhang (KPZ) interfaces growing inward from ring-shaped initial conditions, experimentally and numerically, using growth of a turbulent state in liquid-crystal electroconvection and an off-lattice Eden model, respectively. To realize the ring initial condition experimentally, we introduce a holography-based technique that allows us to design the initial condition arbitrarily. Then, we find that fluctuation properties of ingrowing circular interfaces are distinct from those for the curved or circular KPZ subclass and, instead, are characterized by the flat subclass...
July 21, 2017: Physical Review Letters
Vishal Panchal, Héctor Corte-León, Boris Gribkov, Luis Alfredo Rodriguez, Etienne Snoeck, Alessandra Manzin, Enrico Simonetto, Silvia Vock, Volker Neu, Olga Kazakova
We present a comprehensive method for visualisation and quantification of the magnetic stray field of magnetic force microscopy (MFM) probes, applied to the particular case of custom-made multi-layered probes with controllable high/low magnetic moment states. The probes consist of two decoupled magnetic layers separated by a non-magnetic interlayer, which results in four stable magnetic states: ±ferromagnetic (FM) and ±antiferromagnetic (A-FM). Direct visualisation of the stray field surrounding the probe apex using electron holography convincingly demonstrates a striking difference in the spatial distribution and strength of the magnetic flux in FM and A-FM states...
August 3, 2017: Scientific Reports
Minghuan Liu, Yonggang Liu, Zenghui Peng, Shaoxin Wang, Qidong Wang, Quanquan Mu, Zhaoliang Cao, Li Xuan
Organic solid-state tri-wavelength lasing was demonstrated from dye-doped holographic polymer-dispersed liquid crystal (HPDLC) distributed feedback (DFB) laser with semiconducting polymer poly[-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene-vinylene] (MEH-PPV) and laser dye [4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran] (DCM) by a one-step holography technique, which centered at 605.5 nm, 611.9 nm, and 671.1 nm. The temperature-dependence tuning range for the tri-wavelength dye-doped HPDLC DFB laser was as high as 8 nm...
May 7, 2017: Materials
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