| 1. |
- Gu, Bobo, et al.
(författare)
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Fiber-optic metal ion sensor based on thin-core fiber modal interferometer with nanocoating self-assembled via hydrogen bonding
- 2011
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 160:1, s. 1174-1179
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Tidskriftsartikel (refereegranskat)abstract
- A new fiber-optic metal ion sensor based on a thin-core fiber modal interferometer (TCFMI) is presented. Poly(4-vinylpyridine) (P4VP) and poly(acrylic acid) (PAA) are layer-by-layer deposited on the side surface of the TCFMI via hydrogen bonding for the detection of metal ion in aqueous solutions. Ultraviolet-visible (UV-vis) absorption spectroscopy is employed to monitor the self-assembly process, and the thickness and morphology of the nanocoating are characterized by scanning electron microscopy (SEM). When the sensor is immersed into the aqueous solutions containing metal ions, the refractive index (RI) of the nanocoating is changed because of the association of metal ions with the nanocoating, which was verified by energy dispersive X-ray (EDX). Based on the RI sensing capability of TCFMI, one can detect the concentration of metal ions through the measurement of the dip wavelength of the sensor's transmission spectrum. The experiment results exhibit that the sensor is reusable and with a fast response in a wide metal ion concentration range (10 nM-0.1 M). The limit of detection (LOD) of the sensor is around 9.6 nM experimentally.
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| 2. |
- Hudson, Lawrence N, et al.
(författare)
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The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project
- 2017
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Ingår i: Ecology and Evolution. - : John Wiley & Sons. - 2045-7758. ; 7:1, s. 145-188
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Tidskriftsartikel (refereegranskat)abstract
- The PREDICTS project-Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)-has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity.
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| 3. |
- Yin, Mingjie, et al.
(författare)
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Highly sensitive and fast responsive fiber-optic modal interferometric pH sensor based on polyelectrolyte complex and polyelectrolyte self-assembled nanocoating
- 2011
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Ingår i: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 399:10, s. 3623-3631
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Tidskriftsartikel (refereegranskat)abstract
- A new fiber-optic pH sensor is demonstrated by coating negatively charged polyelectrolyte complex (PEC-) nanoparticles, made of sodium carboxymethyl cellulose and poly(diallyldimethylammonium chloride) (PDDA), and positively charged PDDA on the surface of a thin-core fiber modal interferometer (TCFMI) with a layer-by-layer (LbL) electrostatic self-assembly method. The fabricated TCFMI pH sensor has different transmission dip wavelengths under different pH values and shows high sensitivities of 0.6 nm/pH unit and -0.85 nm/pH unit for acidic and alkaline solutions, respectively, and short response time of 30-50 s. The LbL electrostatic self-assembly process of a PEC-/PDDA multilayer is traced by quartz crystal microbalance and shows a fast thickness growth. Atomic force microscopy shows the root mean square (RMS) surface roughness of electrostatic self-assembly nanocoating of polyelectrolyte complex/polyelectrolyte is much higher than that of polyelectrolyte/polyelectrolyte due to the larger size of PEC- colloidal nanoparticles. The enhanced RMS surface roughness and thickness of the nanocoating can shorten the response time and raise the sensitivity of the TCFMI pH sensor, respectively. In addition, the TCFMI pH sensor has highly reversible performance and good durability.
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| 4. |
- Zhou, Bin, et al.
(författare)
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Cladding-Mode-Recoupling-Based Tilted Fiber Bragg Grating Sensor With a Core-Diameter-Mismatched Fiber Section
- 2010
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Ingår i: IEEE PHOTONICS J. - 1943-0655. ; 2:2, s. 152-157
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a reflective fiber-optic sensor with a core-diameter-mismatched fiber section and cladding-mode recoupling in a tilted fiber Bragg grating (TFBG). High-order cladding modes are efficiently excited by either a multimode fiber or a thin-core fiber section and recoupled back to the core mode by the TFBG. A special reflection spectrum with recoupling of cladding mode is then obtained to exploit the applications of evanescent waves in an optical fiber. Experimental results of the sensor to measure the external refractive index are presented.
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