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Khalenkow D, Tormo AD, De Meyst A, Van Der Meeren L, Verduijn J, Rybarczyk J, Vanrompay D, Le Thomas N, Skirtach AG. Chlamydia psittaci infected cell studies by 4Pi Raman and atomic force microscopy. Microscopy (Oxf) 2024:dfae011. [PMID: 38527311 DOI: 10.1093/jmicro/dfae011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 12/22/2023] [Accepted: 02/15/2024] [Indexed: 03/27/2024] Open
Abstract
Chlamydia psittaci is an avian bacterial pathogen that can cause atypical pneumonia in humans via zoonotic transmission. It is a Gram-negative intracellular bacterium that proliferates inside membrane bound inclusions in the cytoplasm of living eukaryotic cells. The study of such cells with C. psittaci inside without destroying them poses a significant challenge. We demonstrated in this work the utility of a combined multitool approach to analyze such complex samples. Atomic force microscopy was applied to obtain high-resolution images of the surface of infected cells upon entrance of bacteria. Atomic force microscopy scans revealed the morphological changes of the cell membrane of Chlamydia infected cells such as changes in roughness of cell membrane and the presence of micro vesicles. 4Pi Raman microscopy was used to image and probe the molecular composition of intracellular bacteria inside intact cells. Information about the structure of the inclusion produced by C. psittaci was obtained and it was found to have a similar molecular fingerprint as that of an intracellular lipid droplet but with less proteins and unsaturated lipids. The presented approach demonstrates complementarity of various microscopy-based approaches and might be useful for characterization of intracellular bacteria.
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Affiliation(s)
- Dmitry Khalenkow
- Department of Biotechnology, Faculty of Bioscience Engineering, Ghent University, Ghent 9000, Belgium
| | - Alejandro Diaz Tormo
- Photonics Research Group, Department of Information Technology, IMEC & Center for Nano-and Biophotonics, Ghent University, Ghent 9000, Belgium
| | - Anne De Meyst
- Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent 9000, Belgium
| | - Louis Van Der Meeren
- Department of Biotechnology, Faculty of Bioscience Engineering, Ghent University, Ghent 9000, Belgium
| | - Joost Verduijn
- Department of Biotechnology, Faculty of Bioscience Engineering, Ghent University, Ghent 9000, Belgium
| | - Joanna Rybarczyk
- Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent 9000, Belgium
| | - Daisy Vanrompay
- Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent 9000, Belgium
| | - Nicolas Le Thomas
- Photonics Research Group, Department of Information Technology, IMEC & Center for Nano-and Biophotonics, Ghent University, Ghent 9000, Belgium
| | - Andre G Skirtach
- Department of Biotechnology, Faculty of Bioscience Engineering, Ghent University, Ghent 9000, Belgium
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Lin C, Peñaranda JSD, Dendooven J, Detavernier C, Schaubroeck D, Boon N, Baets R, Le Thomas N. UV photonic integrated circuits for far-field structured illumination autofluorescence microscopy. Nat Commun 2022; 13:4360. [PMID: 35896536 PMCID: PMC9329385 DOI: 10.1038/s41467-022-31989-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 07/13/2022] [Indexed: 12/04/2022] Open
Abstract
Ultra-violet (UV) light has still a limited scope in optical microscopy despite its potential advantages over visible light in terms of optical resolution and of interaction with a wide variety of biological molecules. The main challenge is to control in a robust, compact and cost-effective way UV light beams at the level of a single optical spatial mode and concomitantly to minimize the light propagation loss. To tackle this challenge, we present here photonic integrated circuits made of aluminum oxide thin layers that are compatible with both UV light and high-volume manufacturing. These photonic circuits designed at a wavelength of 360 nm enable super-resolved structured illumination microscopy with conventional wide-field microscopes and without modifying the usual protocol for handling the object to be imaged. As a biological application, we show that our UV photonic chips enable to image the autofluorescence of yeast cells and reveal features unresolved with standard wide-field microscopy. Here, the authors develop a UV-compatible photonic integrated circuit for structured illumination microscopy on a conventional wide-field microscope. Operating at a wavelength of 360 nm, they generate switchable far-field fringe patterns, and demonstrate autofluorescence imaging of yeast cells.
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Affiliation(s)
- Chupao Lin
- Photonics Research Group, INTEC Department, Ghent University-imec, 9052, Ghent, Belgium. .,Center for Nano- and Biophotonics, Ghent University, Ghent, Belgium.
| | | | - Jolien Dendooven
- Department of Solid State Sciences, CoCooN, Ghent University, 9000, Ghent, Belgium
| | | | - David Schaubroeck
- Centre of Microsystems Technology (CMST), imec and Ghent University, 9052, Zwijnaarde, Belgium
| | - Nico Boon
- Center for Microbial Ecology and Technology (CMET), Ghent University, Gent, Belgium
| | - Roel Baets
- Photonics Research Group, INTEC Department, Ghent University-imec, 9052, Ghent, Belgium.,Center for Nano- and Biophotonics, Ghent University, Ghent, Belgium
| | - Nicolas Le Thomas
- Photonics Research Group, INTEC Department, Ghent University-imec, 9052, Ghent, Belgium. .,Center for Nano- and Biophotonics, Ghent University, Ghent, Belgium.
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Liu Z, Zhao H, Baumgartner B, Lendl B, Stassen A, Skirtach A, Thomas NL, Baets R. Ultra-sensitive slot-waveguide-enhanced Raman spectroscopy for aqueous solutions of non-polar compounds using a functionalized silicon nitride photonic integrated circuit. Opt Lett 2021; 46:1153-1156. [PMID: 33649680 DOI: 10.1364/ol.416464] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 01/22/2021] [Indexed: 06/12/2023]
Abstract
We demonstrate an ultra-sensitive waveguide-enhanced Raman sensor for low concentration organic compounds dissolved in water. The spectra are obtained using silicon nitride slot waveguides coated with a thin film of hexamethyldisilazane-modified mesoporous silica. Enriched locally by 600-fold within the coating, a micromolar level of cyclohexanone is probed. The sensor is also capable of simultaneous quantification of multiple analytes, and the adsorbed analytes can be completely released from the coating. These properties make this on-chip Raman sensor promising for diverse applications, especially for the monitoring of non-polar organics and biomolecules in aqueous environments.
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Raza A, Clemmen S, Wuytens P, de Goede M, Tong ASK, Le Thomas N, Liu C, Suntivich J, Skirtach AG, Garcia-Blanco SM, Blumenthal DJ, Wilkinson JS, Baets R. High index contrast photonic platforms for on-chip Raman spectroscopy. Opt Express 2019; 27:23067-23079. [PMID: 31510589 DOI: 10.1364/oe.27.023067] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 06/21/2019] [Indexed: 05/24/2023]
Abstract
Nanophotonic waveguide enhanced Raman spectroscopy (NWERS) is a sensing technique that uses a highly confined waveguide mode to excite and collect the Raman scattered signal from molecules in close vicinity of the waveguide. The most important parameters defining the figure of merit of an NWERS sensor include its ability to collect the Raman signal from an analyte, i.e. "the Raman conversion efficiency" and the amount of "Raman background" generated from the guiding material. Here, we compare different photonic integrated circuit (PIC) platforms capable of on-chip Raman sensing in terms of the aforementioned parameters. Among the four photonic platforms under study, tantalum oxide and silicon nitride waveguides exhibit high signal collection efficiency and low Raman background. In contrast, the performance of titania and alumina waveguides suffers from a strong Raman background and a weak signal collection efficiency, respectively.
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Errando-Herranz C, Le Thomas N, Gylfason KB. Low-power optical beam steering by microelectromechanical waveguide gratings. Opt Lett 2019; 44:855-858. [PMID: 30768004 DOI: 10.1364/ol.44.000855] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 01/13/2019] [Indexed: 05/25/2023]
Abstract
Optical beam steering is key for optical communications, laser mapping (lidar), and medical imaging. For these applications, integrated photonics is an enabling technology that can provide miniaturized, lighter, lower-cost, and more power-efficient systems. However, common integrated photonic devices are too power demanding. Here, we experimentally demonstrate, for the first time, to the best of our knowledge, beam steering by microelectromechanical (MEMS) actuation of a suspended silicon photonic waveguide grating. Our device shows up to 5.6° beam steering with 20 V actuation and power consumption below the μW level, i.e., more than five orders of magnitude lower power consumption than previous thermo-optic tuning methods. The novel combination of MEMS with integrated photonics presented in this work lays ground for the next generation of power-efficient optical beam steering systems.
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Diaz Tormo A, Khalenkow D, Saurav K, Skirtach AG, Thomas NL. Superresolution 4π Raman microscopy. Opt Lett 2017; 42:4410-4413. [PMID: 29088176 DOI: 10.1364/ol.42.004410] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 09/26/2017] [Indexed: 06/07/2023]
Abstract
The advent of 4π microscopy broke the conventional optical resolution limit in the axial direction of the microscope. In combination with fluorescence microscopy, it broadened the knowledge of cell biology at the expense of perturbing the samples with extrinsic fluorescent labels. In contrast, Raman microscopy acquires the molecular fingerprint of the sample without the need of extrinsic labels, and therefore improving its resolution can make an even greater impact. Here, we take advantage of the improved axial resolution of a 4π configuration to form a 4π Raman microscope. With this microscope, we independently and simultaneously analyzed different nanolayers in a multilayer stack. We identified their chemical composition and retrieved their relative subwavelength optical separation with a precision of 6 nm.
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Xiao M, Hu Z, Wang Z, Li Y, Tormo AD, Le Thomas N, Wang B, Gianneschi NC, Shawkey MD, Dhinojwala A. Bioinspired bright noniridescent photonic melanin supraballs. Sci Adv 2017; 3:e1701151. [PMID: 28929137 PMCID: PMC5600532 DOI: 10.1126/sciadv.1701151] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 08/17/2017] [Indexed: 05/20/2023]
Abstract
Structural colors enable the creation of a spectrum of nonfading colors without pigments, potentially replacing toxic metal oxides and conjugated organic pigments. However, significant challenges remain to achieve the contrast needed for a complete gamut of colors and a scalable process for industrial application. We demonstrate a feasible solution for producing structural colors inspired by bird feathers. We have designed core-shell nanoparticles using high-refractive index (RI) (~1.74) melanin cores and low-RI (~1.45) silica shells. The design of these nanoparticles was guided by finite-difference time-domain simulations. These nanoparticles were self-assembled using a one-pot reverse emulsion process, which resulted in bright and noniridescent supraballs. With the combination of only two ingredients, synthetic melanin and silica, we can generate a full spectrum of colors. These supraballs could be directly added to paints, plastics, and coatings and also used as ultraviolet-resistant inks or cosmetics.
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Affiliation(s)
- Ming Xiao
- Department of Polymer Science, The University of Akron, Akron, OH 44325, USA
| | - Ziying Hu
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
- Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093, USA
| | - Zhao Wang
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Yiwen Li
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, P. R. China
| | - Alejandro Diaz Tormo
- Photonics Research Group, Department of Information Technology, Ghent University–imec, Center for Nano- and Biophotonics (NB-Photonics), 9000 Ghent, Belgium
| | - Nicolas Le Thomas
- Photonics Research Group, Department of Information Technology, Ghent University–imec, Center for Nano- and Biophotonics (NB-Photonics), 9000 Ghent, Belgium
| | - Boxiang Wang
- Institute of Engineering Thermophysics, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Nathan C. Gianneschi
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
- Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093, USA
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
- Corresponding author. (A.D.); (M.D.S.); (N.C.G.)
| | - Matthew D. Shawkey
- Evolution and Optics of Nanostructures Group, Department of Biology, The University of Ghent, 9000 Ghent, Belgium
- Department of Biology and Integrated Bioscience Program, University of Akron, Akron, OH 44325, USA
- Corresponding author. (A.D.); (M.D.S.); (N.C.G.)
| | - Ali Dhinojwala
- Department of Polymer Science, The University of Akron, Akron, OH 44325, USA
- Corresponding author. (A.D.); (M.D.S.); (N.C.G.)
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Dhakal A, Wuytens P, Raza A, Le Thomas N, Baets R. Silicon Nitride Background in Nanophotonic Waveguide Enhanced Raman Spectroscopy. Materials (Basel) 2017; 10:ma10020140. [PMID: 28772499 PMCID: PMC5459205 DOI: 10.3390/ma10020140] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 02/01/2017] [Accepted: 02/04/2017] [Indexed: 11/16/2022]
Abstract
Recent studies have shown that evanescent Raman spectroscopy using a silicon nitride (SiN) nanophotonic waveguide platform has higher signal enhancement when compared to free-space systems. However, signal-to-noise ratio from the waveguide at a low analyte concentration is constrained by the shot-noise from the background light originating from the waveguide itself. Hence, understanding the origin and properties of this waveguide background luminescence (WGBL) is essential to developing mitigation strategies. Here, we identify the dominating component of the WGBL spectrum composed of a broad Raman scattering due to momentum selection-rule breaking in amorphous materials, and several peaks specific to molecules embedded in the core. We determine the maximum of the Raman scattering efficiency of the WGBL at room temperature for 785 nm excitation to be 4.5 ± 1 × 10−9 cm−1·sr−1, at a Stokes shift of 200 cm−1. This efficiency decreases monotonically for higher Stokes shifts. Additionally, we also demonstrate the use of slotted waveguides and quasi-transverse magnetic polarization as some mitigation strategies.
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Affiliation(s)
- Ashim Dhakal
- Photonics Research Group, INTEC Department, Ghent University/IMEC, Gent 9000, Belgium.
- Center for Nano- and Biophotonics, Ghent University, Gent 9000, Belgium.
- Phutung Research Institute, Balaju-16, Kathmandu 44611, Nepal.
| | - Pieter Wuytens
- Photonics Research Group, INTEC Department, Ghent University/IMEC, Gent 9000, Belgium.
- Center for Nano- and Biophotonics, Ghent University, Gent 9000, Belgium.
- Department of Molecular Biotechnology, Ghent University, Gent 9000, Belgium.
| | - Ali Raza
- Photonics Research Group, INTEC Department, Ghent University/IMEC, Gent 9000, Belgium.
- Center for Nano- and Biophotonics, Ghent University, Gent 9000, Belgium.
| | - Nicolas Le Thomas
- Photonics Research Group, INTEC Department, Ghent University/IMEC, Gent 9000, Belgium.
- Center for Nano- and Biophotonics, Ghent University, Gent 9000, Belgium.
| | - Roel Baets
- Photonics Research Group, INTEC Department, Ghent University/IMEC, Gent 9000, Belgium.
- Center for Nano- and Biophotonics, Ghent University, Gent 9000, Belgium.
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Dhakal A, Peyskens F, Clemmen S, Raza A, Wuytens P, Zhao H, Le Thomas N, Baets R. Single mode waveguide platform for spontaneous and surface-enhanced on-chip Raman spectroscopy. Interface Focus 2016; 6:20160015. [PMID: 27499842 PMCID: PMC4918833 DOI: 10.1098/rsfs.2016.0015] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We review an on-chip approach for spontaneous Raman spectroscopy and surface-enhanced Raman spectroscopy based on evanescent excitation of the analyte as well as evanescent collection of the Raman signal using complementary metal oxide semiconductor (CMOS)-compatible single mode waveguides. The signal is either directly collected from the analyte molecules or via plasmonic nanoantennas integrated on top of the waveguides. Flexibility in the design of the geometry of the waveguide, and/or the geometry of the antennas, enables optimization of the collection efficiency. Furthermore, the sensor can be integrated with additional functionality (sources, detectors, spectrometers) on the same chip. In this paper, the basic theoretical concepts are introduced to identify the key design parameters, and some proof-of-concept experimental results are reviewed.
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Affiliation(s)
- Ashim Dhakal
- Department of Information Technology (INTEC), Photonics Research Group, University of Ghent–imec, Ghent, Belgium
- Center for Nano- and Biophotonics, Ghent University, Ghent, Belgium
| | - Frédéric Peyskens
- Department of Information Technology (INTEC), Photonics Research Group, University of Ghent–imec, Ghent, Belgium
- Center for Nano- and Biophotonics, Ghent University, Ghent, Belgium
| | - Stéphane Clemmen
- Department of Information Technology (INTEC), Photonics Research Group, University of Ghent–imec, Ghent, Belgium
- Center for Nano- and Biophotonics, Ghent University, Ghent, Belgium
| | - Ali Raza
- Department of Information Technology (INTEC), Photonics Research Group, University of Ghent–imec, Ghent, Belgium
- Center for Nano- and Biophotonics, Ghent University, Ghent, Belgium
| | - Pieter Wuytens
- Department of Information Technology (INTEC), Photonics Research Group, University of Ghent–imec, Ghent, Belgium
- Center for Nano- and Biophotonics, Ghent University, Ghent, Belgium
- Department of Molecular Biotechnology, Ghent University, Ghent, Belgium
| | - Haolan Zhao
- Department of Information Technology (INTEC), Photonics Research Group, University of Ghent–imec, Ghent, Belgium
- Center for Nano- and Biophotonics, Ghent University, Ghent, Belgium
| | - Nicolas Le Thomas
- Department of Information Technology (INTEC), Photonics Research Group, University of Ghent–imec, Ghent, Belgium
- Center for Nano- and Biophotonics, Ghent University, Ghent, Belgium
| | - Roel Baets
- Department of Information Technology (INTEC), Photonics Research Group, University of Ghent–imec, Ghent, Belgium
- Center for Nano- and Biophotonics, Ghent University, Ghent, Belgium
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Dhakal A, Raza A, Peyskens F, Subramanian AZ, Clemmen S, Le Thomas N, Baets R. Efficiency of evanescent excitation and collection of spontaneous Raman scattering near high index contrast channel waveguides. Opt Express 2015; 23:27391-404. [PMID: 26480401 DOI: 10.1364/oe.23.027391] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We develop and experimentally verify a theoretical model for the total efficiency η0 of evanescent excitation and subsequent collection of spontaneous Raman signals by the fundamental quasi-TE and quasi-TM modes of a generic photonic channel waveguide. Single-mode silicon nitride (Si3N4) slot and strip waveguides of different dimensions are used in the experimental study. Our theoretical model is validated by the correspondence between the experimental and theoretical absolute values within the experimental errors. We extend our theoretical model to silicon-on-insulator (SOI) and titanium dioxide (TiO2) channel waveguides and study η0 as a function of index contrast, polarization of the mode and the geometry of the waveguides. We report nearly 2.5 (4 and 5) times larger η0 for the fundamental quasi-TM mode when compared to η0 for the fundamental quasi-TE mode of a typical Si3N4 (TiO2 and SOI) strip waveguide. η0 for the fundamental quasi-TE mode of a typical Si3N4, (TiO2 and SOI) slot waveguide is about 7 (22 and 90) times larger when compared to η0 for the fundamental quasi-TE mode of a strip waveguide of the similar dimensions. We attribute the observed enhancement to the higher electric field discontinuity present in high index contrast waveguides.
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Peyskens F, Subramanian AZ, Neutens P, Dhakal A, Van Dorpe P, Le Thomas N, Baets R. Bright and dark plasmon resonances of nanoplasmonic antennas evanescently coupled with a silicon nitride waveguide. Opt Express 2015; 23:3088-3101. [PMID: 25836168 DOI: 10.1364/oe.23.003088] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In this work we investigate numerically and experimentally the resonance wavelength tuning of different nanoplasmonic antennas excited through the evanescent field of a single mode silicon nitride waveguide and study their interaction with this excitation field. Experimental interaction efficiencies up to 19% are reported and it is shown that the waveguide geometry can be tuned in order to optimize this interaction. Apart from the excitation of bright plasmon modes, an efficient coupling between the evanescent field and a dark plasmonic resonance is experimentally demonstrated and theoretically explained as a result of the propagation induced phase delay.
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Viero C, Euden J, Mason SA, Seidel MK, Thomas NL, Zissimopoulos S, Williams AJ. P373Two key regions of the human cardiac ryanodine receptor calcium release channel modulate its gating properties in a dual manner. Cardiovasc Res 2014. [DOI: 10.1093/cvr/cvu091.56] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Dhakal A, Subramanian AZ, Wuytens P, Peyskens F, Le Thomas N, Baets R. Evanescent excitation and collection of spontaneous Raman spectra using silicon nitride nanophotonic waveguides. Opt Lett 2014; 39:4025-8. [PMID: 24978798 DOI: 10.1364/ol.39.004025] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We experimentally demonstrate the use of high contrast, CMOS-compatible integrated photonic waveguides for Raman spectroscopy. We also derive the dependence of collected Raman power with the waveguide parameters and experimentally verify the derived relations. Isopropyl alcohol (IPA) is evanescently excited and detected using single-mode silicon-nitride strip waveguides. We analyze the measured signal strength of pure IPA corresponding to an 819 cm⁻¹ Raman peak due to in-phase C-C-O stretch vibration for several waveguide lengths and deduce a pump power to Raman signal conversion efficiency on the waveguide to be at least 10⁻¹¹ per cm.
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Wang Z, Tian B, Paladugu M, Pantouvaki M, Le Thomas N, Merckling C, Guo W, Dekoster J, Van Campenhout J, Absil P, Van Thourhout D. Polytypic InP nanolaser monolithically integrated on (001) silicon. Nano Lett 2013; 13:5063-5069. [PMID: 24073748 DOI: 10.1021/nl402145r] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
On-chip optical interconnects still miss a high-performance laser monolithically integrated on silicon. Here, we demonstrate a silicon-integrated InP nanolaser that operates at room temperature with a low threshold of 1.69 pJ and a large spontaneous emission factor of 0.04. An epitaxial scheme to grow relatively thick InP nanowires on (001) silicon is developed. The zincblende/wurtzite crystal phase polytypism and the formed type II heterostructures are found to promote lasing over a wide wavelength range.
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Affiliation(s)
- Zhechao Wang
- INTEC Department, Ghent University , Sint-Pietersnieuwstraat 41, Ghent 9000, Belgium
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Shakoor A, Muhammad R, Thomas NL, Silberschmidt VV. Mechanical and thermal characterisation of poly (l-lactide) composites reinforced with hemp fibres. ACTA ACUST UNITED AC 2013. [DOI: 10.1088/1742-6596/451/1/012010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Jágerská J, Zhang H, Diao Z, Le Thomas N, Houdré R. Refractive index sensing with an air-slot photonic crystal nanocavity. Opt Lett 2010; 35:2523-2525. [PMID: 20680045 DOI: 10.1364/ol.35.002523] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We investigate an air-slot photonic crystal cavity for high-precision refractive index sensing. The high quality factor approximately 2.6x10(4) of the cavity, along with a strong overlap between the resonant mode and the hollow core region, allows us to achieve an experimental sensitivity of 510nm per refractive index unit (RUI) and a detection limit below 1x10(-5)RUI. The device has a remarkably low sensing volume of 40aliters, holding less than 1x10(6)molecules.
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Affiliation(s)
- Jana Jágerská
- Institut de Physique de la Matière Condensée, Ecole Polytechnique Fédérale de Lausanne (EPFL),Station 3, CH-1015 Lausanne, Switzerland.
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Berry SD, Lopez-Villalobos N, Beattie EM, Davis SR, Adams LF, Thomas NL, Ankersmit-Udy AE, Stanfield AM, Lehnert K, Ward HE, Arias JA, Spelman RJ, Snell RG. Mapping a quantitative trait locus for the concentration of beta-lactoglobulin in milk, and the effect of beta-lactoglobulin genetic variants on the composition of milk from Holstein-Friesian x Jersey crossbred cows. N Z Vet J 2010; 58:1-5. [PMID: 20200568 DOI: 10.1080/00480169.2010.65053] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
AIM To identify quantitative trait loci (QTL) affecting the concentration of beta-lactoglobulin in milk, and to evaluate the effect of beta-lactoglobulin genetic variants on the concentration of fat, protein and casein in bovine milk. METHODS A herd of 850 F2 Holstein-Friesian x Jersey crossbred cows was produced through mating six Holstein-Friesian x Jersey F1 bulls of high genetic merit with F1 cows from the national herd. A total of 1,610 herd-test records from 556 second-parity crossbreds were analysed. The concentration of fat, protein and casein in milk was measured at peak, mid- and late lactation, during the production seasons of 2003-2004 and 2004-2005. Liveweight was measured daily. DNA from the F2 animals, their F1 dams and sires, and selected grandsires was genotyped across the genome, initially with 285 microsatellite markers, and subsequently with 6,634 single nucleotide polymorphisms (SNP). RESULTS A highly significant QTL for the concentration of beta-lactoglobulin in milk was identified, which coincided with the position of the beta-lactoglobulin gene on bovine Chromosome 11. No other consistently significant QTL for the concentration of beta-lactoglobulin in milk were detected. Cows with the BB beta-lactoglobulin genotype produced milk with a 30% lower concentration of beta-lactoglobulin than cows with the AA genotype. The beta-lactoglobulin polymorphism also explained variation in the proportion of casein in total protein. In addition, the percentage of fat was higher for BB than AA animals, whereas the percentage of total protein, mean daily milk yield and liveweight did not differ between AA and BB animals. CONCLUSIONS A significant QTL determining the concentration of beta-lactoglobulin in milk was identified. Selection of animals for the beta-lactoglobulin B-allele may enable the production of milk naturally enriched for casein, thus allowing a potential increase in the yield of cheese. There may be additional future value in production of bovine milk more like human milk, where decreasing the concentration of beta-lactoglobulin is desirable.
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Affiliation(s)
- S D Berry
- ViaLactia Biosciences, PO Box 109185, Newmarket, Auckland 1149, New Zealand.
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Van Acoleyen K, Bogaerts W, Jágerská J, Le Thomas N, Houdré R, Baets R. Off-chip beam steering with a one-dimensional optical phased array on silicon-on-insulator. Opt Lett 2009; 34:1477-1479. [PMID: 19412311 DOI: 10.1364/ol.34.001477] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Optical phased arrays are versatile components enabling rapid and precise beam steering. An integrated approach is followed in which a 1D optical phased array is fabricated on silicon-on-insulator. The optical phased array consists of 16 parallel grating couplers spaced 2 mum apart. Steering in one direction is done thermo-optically by means of a titanium electrode on top of the structure using the phased array principle, while steering in the other direction is accomplished by wavelength tuning. At a wavelength of 1550 nm, continuous thermo-optical steering of 2.3 degrees and wavelength steering of 14.1 degrees is reported.
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Affiliation(s)
- Karel Van Acoleyen
- Photonics Research Group, Ghent University-Interuniversity MicroElectronics Center, Sint-Pietersnieuwstraat 41, B-9000 Ghent, Belgium.
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Jágerská J, Le Thomas N, Zabelin V, Houdré R, Bogaerts W, Dumon P, Baets R. Experimental observation of slow mode dispersion in photonic crystal coupled-cavity waveguides. Opt Lett 2009; 34:359-361. [PMID: 19183658 DOI: 10.1364/ol.34.000359] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We experimentally investigate the dispersion curve of an integrated silicon-on-insulator coupled-cavity waveguide in a photonic crystal environment using a technique based on far-field imaging. We show that a chain of eight coupled cavities of a moderate Q factor can form a continuous dispersion band characterized by extremely flat dispersion and a group index of 105+/-20 within a 2.6 nm wavelength range. The experimental results are well reproduced by theoretical calculations based on the guided-mode expansion method.
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Affiliation(s)
- Jana Jágerská
- Institut de Photonique et dElectronique Quantiques, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
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Abstract
The RyR (ryanodine receptor) mediates rapid Ca2+ efflux from the ER (endoplasmic reticulum) and is responsible for triggering numerous Ca2+-activated physiological processes. The most studied RyR-mediated process is excitation-contraction coupling in striated muscle, where plasma membrane excitation is transmitted to the cell interior and results in Ca2+ efflux that triggers myocyte contraction. Recently, single-residue mutations in the cardiac RyR (RyR2) have been identified in families that exhibit CPVT (catecholaminergic polymorphic ventricular tachycardia), a condition in which physical or emotional stress can trigger severe tachyarrhythmias that can lead to sudden cardiac death. The RyR2 mutations in CPVT are clustered in the N- and C-terminal domains, as well as in a central domain. Further, a critical signalling role for dysfunctional RyR2 has also been implicated in the generation of arrhythmias in the common condition of HF (heart failure). We have prepared cardiac RyR2 plasmids with various CPVT mutations to enable expression and analysis of Ca2+ release mediated by the wild-type and mutated RyR2. These studies suggest that the mutational locus may be important in the mechanism of Ca2+ channel dysfunction. Understanding the causes of aberrant Ca2+ release via RyR2 may assist in the development of effective treatments for the ventricular arrhythmias that often leads to sudden death in HF and in CPVT.
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Affiliation(s)
- N L Thomas
- Department of Cardiology, Wales Heart Research Institute, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK.
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Thomas NL, Coughtrie MWH. Sulfation of apomorphine by human sulfotransferases: evidence of a major role for the polymorphic phenol sulfotransferase, SULT1A1. Xenobiotica 2004; 33:1139-48. [PMID: 14660177 DOI: 10.1080/00498250310001609192] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
1. The relative roles of various members of the human sulfotransferase (SULT) enzyme family in the metabolism of apomorphine, a dopamine receptor antagonist used in the treatment of Parkinson's disease and, more recently, erectile dysfunction, were examined. In humans, sulfation is the major route of metabolism of this drug. 2. Using recombinant SULTs expressed in Escherichia coli, R(--)-apomorphine sulfation was studied using the universal barium precipitation assay in the presence of [35S] 3'-phosphoadenosine 5'-phosphosulfate and SULTs 1A1, 1A2, 1A3, 1B1, 1C2, 1E1 and 2A1. It was shown that SULTs 1A1, 1A2, 1A3 and 1E1 all sulfated apomorphine to varying extents. Low activity with SULT1B1 was only seen at the highest concentration (100 microM) and no activity with SULT1C2 or SULT2A1 was observed. 3. Kinetic analysis using purified recombinant SULTs showed that 1A1, 1A3 and 1E1 all had similar Vmax/Km values, although SULT1E1 had a slightly lower Km at around 1 microM compared with approximately 4 microM for the other SULTs. 4. By correlating apomorphine sulfation (at 10 microM) in a bank of 28 liver cytosols with SULT activity towards 10 microM 4-nitrophenol (SULT1A1) and 0.2 microM 17beta-oestradiol (SULT1E1), a strong correlation with SULT1A1 activity was clearly demonstrated, suggesting this enzyme was primarily responsible for hepatic apomorphine sulfation. 5. These findings were confirmed using immuno-inhibition experiments with antibodies against SULT1A and SULT1E1, which showed preferential inhibition of apomorphine sulfation in human liver cytosol by anti-SULT1A. 6. The results strongly implicate SULT1A1 as the major enzyme responsible for hepatic apomorphine metabolism. As SULT1A1 is subject to a common functional polymorphism, sulfation phenotype may be an important determinant of susceptibility to side-effects of apomorphine and/or efficacy of treatment.
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Affiliation(s)
- N L Thomas
- Department of Molecular and Cellular Pathology, University of Dundee, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK
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Gower IF, Songer TJ, Hylton H, Thomas NL, Ekoe JM, Lave LB, LaPorte RE. Epidemiology of insulin-using commercial motor vehicle drivers. Major variability of state licensing requirements in the U.S. Diabetes Care 1992; 15:1464-7. [PMID: 1468272 DOI: 10.2337/diacare.15.11.1464] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Licensing agencies in many areas, including the U.S., prohibit insulin-using individuals from driving CMVs or large trucks. This study examined the debate over the risks of licensing insulin-using individuals to drive CMVs as an occupation, and the variations in regulations of different states. RESEARCH DESIGN AND METHODS As part of an ongoing review of the regulations governing interstate commerce in the U.S., we surveyed all 50 states and Washington, D.C. to determine the regulations concerning intrastate driving. We received responses from 48 states and D.C., representing 95% of the U.S. population. RESULTS Only 9 states reported preventing insulin users from acquiring a CMV license, whereas 39 states and D.C. permitted licensing within state boundaries. Of the states allowing insulin users to drive, 26 placed special requirements on CMV licensing. CONCLUSIONS The results indicate that, despite a standardized U.S. federal law for driving across states, enormous variability exists in the policies for driving within states, ranging from no restrictions to a complete ban on CMV driving for insulin users.
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Affiliation(s)
- I F Gower
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, PA 15261
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Grey TC, Robinson D, Jones JM, Stock SW, Thomas NL. Effect of age and sex on the composition of muscle and skin from a commercial broiler strain. Br Poult Sci 1983; 24:219-31. [PMID: 6883152 DOI: 10.1080/00071668308416733] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The effects of age and sex have been studied on the proximate composition and inorganic constituents in breast, thigh, drumstick and skin from a commercial British broiler strain (Ross 1). Protein content generally increased with age in all muscles and decreased in skin. Protein content in skin of males was always higher than that in females. Moisture content in all muscles decreased with age. In the skin, moisture decreased with age considerably more in females than in males. Fat content increased with age in all tissues, while ash content of breast, thigh and skin decreased with age. Phosphorus, chloride, magnesium and potassium all decreased with age in all the tissues. Thigh and skin calcium content were affected by age, as was the sodium content of drumstick and skin. The sex effect on the inorganic constituents was variable.
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Mead GC, Thomas NL. The bacteriological condition of eviscerated chickens processed under controlled conditions in a spin-chilling system and sampled by two different methods. Br Poult Sci 1973; 14:413-9. [PMID: 4579641 DOI: 10.1080/00071667308416045] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Thomas NL. Case of Hypertrophy of the Colon. Med Exam (Phila) 1839; 2:585-587. [PMID: 38118861 PMCID: PMC10237922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
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Thomas NL. Case of Lumbrici in the Cavity of the Peritoneum. Med Exam (Phila) 1839; 2:77-78. [PMID: 38118813 PMCID: PMC10237870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
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