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https://www.readbyqxmd.com/read/28799676/morphology-visualization-of-irregular-shape-bacteria-by-electron-holography-and-tomography
#1
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
https://www.readbyqxmd.com/read/28793010/asymmetric-bioreduction-of-%C3%AE-ketoesters-derivatives-by-kluyveromyces-marxianus-influence-of-molecular-structure-on-the-conversion-and-enantiomeric-excess
#2
Simone S S Oliveira, Murilo L Bello, Carlos R Rodrigues, Paula L DE Azevedo, Maria C K V Ramos, Francisco R DE Aquino-Neto, Sorele B Fiaux, Luiza R S Dias
This study presents the bioreduction of six β-ketoesters by whole cells of Kluyveromyces marxianus and molecular investigation of a series of 13 β-ketoesters by hologram quantitative structure-activity relationship (HQSAR) in order to relate with conversion and enantiomeric excess of β-stereogenic-hydroxyesters obtained by the same methodology. Four of these were obtained as (R)-configuration and two (S)-configuration, among them four compounds exhibited >99% enantiomeric excess. The β-ketoesters series LUMO maps showed that the β-carbon of the ketoester scaffold are exposed to undergo nucleophilic attack, suggesting a more favorable β-carbon side to enzymatic reduction based on adopted molecular conformation at the reaction moment...
August 7, 2017: Anais da Academia Brasileira de Ciências
https://www.readbyqxmd.com/read/28780143/imaging-the-potential-distribution-of-individual-charged-impurities-on-graphene-by-low-energy-electron-holography
#3
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
https://www.readbyqxmd.com/read/28775295/electromagnetic-reprogrammable-coding-metasurface-holograms
#4
Lianlin Li, Tie Jun Cui, Wei Ji, Shuo Liu, Jun Ding, Xiang Wan, Yun Bo Li, Menghua Jiang, Cheng-Wei Qiu, Shuang Zhang
Metasurfaces have enabled a plethora of emerging functions within an ultrathin dimension, paving way towards flat and highly integrated photonic devices. Despite the rapid progress in this area, simultaneous realization of reconfigurability, high efficiency, and full control over the phase and amplitude of scattered light is posing a great challenge. Here, we try to tackle this challenge by introducing the concept of a reprogrammable hologram based on 1-bit coding metasurfaces. The state of each unit cell of the coding metasurface can be switched between '1' and '0' by electrically controlling the loaded diodes...
August 4, 2017: Nature Communications
https://www.readbyqxmd.com/read/28772368/a-comprehensive-study-of-photorefractive-properties-in-poly-ethylene-glycol-dimethacrylate-ionic-liquid-composites
#5
Mostafa A Ellabban, Gašper Glavan, Jürgen Klepp, Martin Fally
A detailed investigation of the recording, as well as the readout of transmission gratings in composites of poly(ethylene glycol) dimethacrylate (PEGDMA) and ionic liquids is presented. Gratings with a period of about 5.8 micrometers were recorded using a two-wave mixing technique with a coherent laser beam of a 355-nm wavelength. A series of samples with grating thicknesses d 0 = 10 … 150 micrometers, each for two different exposure times, was prepared. The recording kinetics, as well as the post-exposure properties of the gratings were monitored by diffracting a low intensity probe beam at a wavelength of 633 nm for Bragg incidence...
December 24, 2016: Materials
https://www.readbyqxmd.com/read/28751782/reconstruction-of-local-frequencies-for-recovering-the-unwrapped-phase-in-optical-interferometry
#6
Julio C Estrada, Jose L Marroquin, Orlando M Medina
In optics, when interferograms or digital holograms are recorded and their phase is recovered, it is common to obtain a wrapped phase with some errors, noise and artifacts such as singularities due to the non linearities of the demodulation process. This paper shows how to reconstruct the frequency field of the wrapped phase by using adaptive Gabor filters. Gabor filters are Gaussian quadrature filters tuned in at a certain frequency. We adapt these Gabor filters by tuning them locally and estimating the frequency using wrapped finite differences of the estimated phase...
July 27, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28724934/full-color-large-area-transmissive-holograms-enabled-by-multi-level-diffractive-optics
#7
Nabil Mohammad, Monjurul Meem, Xiaowen Wan, Rajesh Menon
We show that multi-level diffractive microstructures can enable broadband, on-axis transmissive holograms that can project complex full-color images, which are invariant to viewing angle. Compared to alternatives like metaholograms, diffractive holograms utilize much larger minimum features (>10 µm), much smaller aspect ratios (<0.2) and thereby, can be fabricated in a single lithography step over relatively large areas (>30 mm ×30 mm). We designed, fabricated and characterized holograms that encode various full-color images...
July 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28696538/dimension-controllable-microtube-arrays-by-dynamic-holographic-processing-as-3d-yeast-culture-scaffolds-for-asymmetrical-growth-regulation
#8
Shengyun Ji, Liang Yang, Yanlei Hu, Jincheng Ni, Wenqiang Du, Jiawen Li, Gang Zhao, Dong Wu, Jiaru Chu
Transparent microtubes can function as unique cell culture scaffolds, because the tubular 3D microenvironment they provide is very similar to the narrow space of capillaries in vivo. However, how to realize the fabrication of microtube-arrays with variable cross-section dynamically remains challenging. Here, a dynamic holographic processing method for producing high aspect ratio (≈20) microtubes with tunable outside diameter (6-16 µm) and inside diameter (1-10 µm) as yeast culture scaffolds is reported...
July 11, 2017: Small
https://www.readbyqxmd.com/read/28682622/multiplexed-holograms-by-surface-plasmon-propagation-and-polarized-scattering
#9
Ji Chen, Tao Li, Shuming Wang, Shining Zhu
Thanks to the superiority in controlling the optical wave fronts, plasmonic nanostructures have led to various striking applications, among which metasurface holograms have been well developed and endowed with strong multiplexing capability. Here, we report a new design of multiplexed plasmonic hologram, which allows for reconstruction of multiple holographic images in free space by scatterings of surface plasmon polariton (SPP) waves in different propagation directions. Besides, the scattered polarization states can be further modulated by arranging the orientations of nanoscatterers...
July 10, 2017: Nano Letters
https://www.readbyqxmd.com/read/28674409/conformable-holographic-metasurfaces
#10
James Burch, Dandan Wen, Xianzhong Chen, Andrea Di Falco
Metasurface holograms are typically fabricated on rigid substrates. Here we experimentally demonstrate broadband, flexible, conformable, helicity multiplexed metasurface holograms operating in the visible range, offering increased potential for real life out-of-the-lab applications. Two symmetrically distributed holographic images are obtained when circularly polarized light impinges on the reflective-type metasurface positioned on non-planar targets. The two off-axis images with high fidelity are interchangeable by controlling the helicity of incident light...
July 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28652591/opposite-view-digital-holographic-microscopy-with-autofocusing-capability
#11
Juanjuan Zheng, Peng Gao, Xiaopeng Shao
Digital holographic microscopy (DHM) has its intrinsic ability to refocusing a sample by numerically propagating an object wave from its hologram plane to its image plane. In this paper opposite-view digital holographic microscopy (OV-DHM) is demonstrated for autofocusing, namely, digitally determining the location of the image plane, and refocusing the object wave without human intervention. In OV-DHM, a specimen is illuminated from two sides in a 4π-alike configuration, and two holograms are generated and recorded by a CCD camera along two orthogonal polarization orientations...
June 26, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28646270/release-from-pi-an-analysis-and-a-model
#12
D J K Mewhort, Kevin D Shabahang, D R J Franklin
Recall decreases across a series of subspan immediate-recall trials but rebounds if the semantic category of the words is changed, an example of release from proactive interference (RPI). The size of the rebound depends on the semantic categories used and ranges from 0% to 95%. We used a corpus of novels to create vectors representing the meaning of about 40,000 words using the BEAGLE algorithm. The distance between categories and spread within categories jointly predicted the size of the RPI. We used a holographic model for recall equipped with a lexicon of BEAGLE vectors representing the meaning of words...
June 23, 2017: Psychonomic Bulletin & Review
https://www.readbyqxmd.com/read/28635308/combined-hqsar-topomer-comfa-homology-modeling-and-docking-studies-on-triazole-derivatives-as-sglt2-inhibitors
#13
Shuling Yu, Jintao Yuan, Yi Zhang, Shufang Gao, Ying Gan, Meng Han, Yuewen Chen, Qiaoqiao Zhou, Jiahua Shi
AIM: Sodium-glucose cotransporter 2 (SGLT2) is a promising target for diabetes therapy. We aimed to develop computational approaches to identify structural features for more potential SGLT2 inhibitors. MATERIALS & METHODS: In this work, 46 triazole derivatives as SGLT2 inhibitors were studied using a combination of several approaches, including hologram quantitative structure-activity relationships (HQSAR), topomer comparative molecular field analysis (CoMFA), homology modeling, and molecular docking...
June 21, 2017: Future Medicinal Chemistry
https://www.readbyqxmd.com/read/28614342/controlled-noncanonical-vortices-from-higher-order-fractional-screw-dislocations
#14
Satyajit Maji, Maruthi M Brundavanam
A pair of stable noncanonical scalar vortices of the same charge is generated experimentally across the cross section of an optical beam using a computer-generated hologram with higher-order fractional screw dislocation. The noncanonical nature of the generated vortices is identified by the gradient of the phase around each vortex and also the crossing angle between the zero contours of the real and imaginary parts of the optical field. The anisotropy of the vortices is controlled by the fractional order of the computer-generated hologram...
June 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28614333/dual-page-reproduction-to-increase-the-data-transfer-rate-in-holographic-memory
#15
Tetsuhiko Muroi, Yutaro Katano, Nobuhiro Kinoshita, Norihiko Ishii
To increase the reproduced data transfer rate in holographic memory, we have investigated simultaneous reproduction of two data pages. By irradiating s- and p-polarization reference beams whose angle gap is equal to the angle between the neighboring data pages in angle-multiplexed holograms, two different data pages can simultaneously be reproduced with a bit error rate low enough to decode. This technology is effective to double the data transfer rate in holographic memory.
June 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28598408/anti-mycobacterial-evaluation-of-7-chloro-4-aminoquinolines-and-hologram-quantitative-structure-activity-relationship-hqsar-modeling-of-amino-imino-tautomers
#16
Marcelle L F Bispo, Camilo H S Lima, Laura N F Cardoso, André L P Candéa, Flávio A F M Bezerra, Maria C S Lourenço, Maria G M O Henriques, Ricardo B Alencastro, Carlos R Kaiser, Marcus V N Souza, Magaly G Albuquerque
In an ongoing research program for the development of new anti-tuberculosis drugs, we synthesized three series (A, B, and C) of 7-chloro-4-aminoquinolines, which were evaluated in vitro against Mycobacterium tuberculosis (MTB). Now, we report the anti-MTB and cytotoxicity evaluations of a new series, D (D01-D21). Considering the active compounds of series A (A01-A13), B (B01-B13), C (C01-C07), and D (D01-D09), we compose a data set of 42 compounds and carried out hologram quantitative structure-activity relationship (HQSAR) analysis...
June 9, 2017: Pharmaceuticals
https://www.readbyqxmd.com/read/28584259/complex-beam-shaping-based-on-an-equivalent-q-plate-system-and-analysis-of-its-properties-using-digital-holography-polarization-imaging
#17
Ching-Han Yang, Andy Ying-Guey Fuh
In this study, we generate various complex beams carrying angular momentum (AM) by using a programmable beam shaping system to mimic typical q-plates. When a circularly polarized wave is incident onto the system, the emerging beam reverses its spin handedness and obtains a spatial phase factor. This phase factor can be engineered by designing a computer-generated hologram (CGH) and applying it to a spatial light modulator (SLM) to produce a beam with controllable spatially distributed orbital angular momentum (OAM) density...
June 5, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28569850/tunable-time-resolved-tick-tock-pulsed-digital-holographic-microscopy-for-ultrafast-events
#18
Yu-Chih Lin, Chau-Jern Cheng, Li-Chien Lin
This study presents a time-resolved imaging technique for detecting ultrafast events in the sample with tunable tick-tock pulses in common-path digital holographic microscopy. The tick-tock pulses are generated from the same single femtosecond pulse source and manipulated through a spatial-multiplexing encoding/decoding scheme with two complementary binary codes for digital hologram recording and reconstruction. The spatial-multiplexing encoding/decoding scheme with compressive sensing on the Fresnel digital hologram is used to recover missing data and achieve high-fidelity wavefront reconstruction...
June 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/28562002/dual-imprinted-polymer-thin-films-via-pattern-directed-self-organization
#19
Danielle Grolman, Diya Bandyopadhyay, Abdullah Al-Enizi, Ahmed Elzatahry, Alamgir Karim
Synthetic topographically patterned films and coatings are typically contoured on one side, yet many of nature's surfaces have distinct textures on different surfaces of the same object. Common examples are the top and bottom sides of the butterfly wing or lotus leaf, onion shells, and the inside versus outside of the stem of a flower. Inspired by nature, we create dual (top and bottom) channel patterned polymer films. To this end, we first develop a novel fabrication method to create ceramic line channel relief structures by converting the oligomeric residue of stamped poly(dimethylsiloxane) (PDMS) nanopatterns on silicon substrates to glass (SiOx, silica) by ultraviolet-ozone (UVO) exposure...
June 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28537248/measuring-the-orbital-angular-momentum-spectrum-of-an-electron-beam
#20
Vincenzo Grillo, Amir H Tavabi, Federico Venturi, Hugo Larocque, Roberto Balboni, Gian Carlo Gazzadi, Stefano Frabboni, Peng-Han Lu, Erfan Mafakheri, Frédéric Bouchard, Rafal E Dunin-Borkowski, Robert W Boyd, Martin P J Lavery, Miles J Padgett, Ebrahim Karimi
Electron waves that carry orbital angular momentum (OAM) are characterized by a quantized and unbounded magnetic dipole moment parallel to their propagation direction. When interacting with magnetic materials, the wavefunctions of such electrons are inherently modified. Such variations therefore motivate the need to analyse electron wavefunctions, especially their wavefronts, to obtain information regarding the material's structure. Here, we propose, design and demonstrate the performance of a device based on nanoscale holograms for measuring an electron's OAM components by spatially separating them...
May 24, 2017: Nature Communications
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