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Patel NA, Alagappan PN, Pan C, Karth P. A mobile vision testing application based on dynamic distance determination from the human corneal limbus. Health Informatics J 2020; 26:3037-3055. [PMID: 32993413 DOI: 10.1177/1460458220958537] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Here we present a mobile application that accurately determines the distance between an optical sensor and the human corneal limbus for visual acuity assessment. The application uses digital image processing and randomized circle detection to locate the cornea. Then, a reference scaling measurement is employed to calculate distance from the sensor to a user. To determine accuracy and generalizability, testing was conducted both with 200 static images, 25 images each of males and females for four ethnic groups from a facial image database, and live image streams from a test subject. Average absolute corneal radius error over 10 trials for the static images was 6.36%, while average absolute distance error for the live image streams was less than 1%. Subsequently, distance measurements were used to scale letter sizes for a Snellen Chart-based visual acuity assessment. This system enables monitoring of chronic retinal diseases, as patients can quickly and accurately measure their visual acuity through the mobile eye exam suite.
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Alagappan PN, Heimann J, Morrow L, Andreoli E, Barron AR. Easily Regenerated Readily Deployable Absorbent for Heavy Metal Removal from Contaminated Water. Sci Rep 2017; 7:6682. [PMID: 28751753 PMCID: PMC5532212 DOI: 10.1038/s41598-017-06734-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [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: 04/25/2017] [Accepted: 06/15/2017] [Indexed: 11/09/2022] Open
Abstract
Although clean and abundant water is the keystone of thriving communities, increasing demand and volatile climate patterns are depleting rivers and aquifers. Moreover, the quality of such water sources is threatened by noxious contaminants, of which heavy metals represents an area of growing concern. Recently, graphene oxide (GO) has been suggested as an adsorbent; however, a support is desirable to ensure a high surface area and an immobile phase. Herein, we described the preparation and characterization of a supported-epoxidized carbon nanotube (SENT) via the growth of multi walled carbon nanotubes (MWNTs) onto a quartz substrate. Subsequent epoxidation provides sufficient functionality to enable adsorbent of heavy metals (Cd2+, Co2+, Cu2+, Hg2+, Ni2+, and Pb2+) from aqueous solution with initial concentrations (60–6000 ppm) chosen to simulate high industrial wastewater contamination. The SENT adsorption efficiency is >99.4% for all metals and the saturation concentration is significantly greater than observed for either GO or acid treated MWNTs. The SENT adsorbent may be readily regenerated under mild conditions using a globally available household chemical, vinegar. 1 g of SENT has the potential to treat 83,000 L of contaminated water down to WHO limits which would be sufficient for 11,000 people.
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Affiliation(s)
- Perry N Alagappan
- Department of Chemistry, Rice University, Houston, Texas, 77005, USA
| | - Jessica Heimann
- Department of Chemistry, Rice University, Houston, Texas, 77005, USA
| | - Lauren Morrow
- Department of Chemistry, Rice University, Houston, Texas, 77005, USA
| | - Enrico Andreoli
- Energy Safety Research Institute, Swansea University, Bay Campus, Swansea, SA1 8EN, Wales, UK
| | - Andrew R Barron
- Department of Chemistry, Rice University, Houston, Texas, 77005, USA. .,Energy Safety Research Institute, Swansea University, Bay Campus, Swansea, SA1 8EN, Wales, UK. .,Department of Materials Science and Nanoengineering, Rice University, Houston, Texas, 77005, USA.
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