• Title/Summary/Keyword: Johns Hopkins University

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The Central Concept for Chitin Catabolic Cascade in Marine Bacterium, Vibrios

  • Jung, Byung-Ok;Roseman, Saul;Park, Jae-Kweon
    • Macromolecular Research
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    • v.16 no.1
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    • pp.1-5
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    • 2008
  • The enzymatic hydrolysis of chitin has been studied for almost a century, and early work established that at least two enzymes are required, a chitinase that mainly yields the disaccharide N,N'-diacetylchitobiose, or $(GlcNAc)_2$, and a "chitobiase", or ${\beta}$-N-acetylglucosaminidase, which gives the final product G1cNAc. This pathway has not been completely identified but has remained the central concept for the chitin catabolism through the $20^{th}$ century1 including in marine bacteria. However, the chitin catabolic cascade is quite complex, as described in this review. This report describes three biologically functional genes involved in the chitin catabolic cascade of Vibrios in an attempt to better understand the metabolic pathway of chitin.

Implementation of Cost-effective Common Path Spectral Domain Free-hand Scanning OCT System

  • Shoujing Guo;Xuan Liu;Jin U. Kang
    • Current Optics and Photonics
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    • v.7 no.2
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    • pp.176-182
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    • 2023
  • Optical coherence tomography (OCT) is being developed to guide various ophthalmic surgical procedures. However, the high cost of the intraoperative OCT system limits its availability mostly to the largest hospitals and healthcare systems. In this paper, we present a design and evaluation of a low-cost intraoperative common-path free-hand scanning OCT system. The lensed fiber imaging probe is designed and fabricated for intraocular use and the free-hand scanning algorithm that could operate at a low scanning speed was developed. Since the system operates at low frequencies, the cost of the overall system is significantly lower than other commercial intraoperative OCT systems. The assembled system is characterized and shows that it meets the design specifications. The handheld OCT imaging probe is tested on multilayer tape phantom and ex-vivo porcine eyes. The results show that the system could be used as an intraoperative intraocular OCT imaging device.