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RISS 인기검색어
- 검색키워드
- 저자 : Sagar Dhakal (검색결과 5 건)
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Qin, Jianwei,Kim, Moon S.,Chao, Kuanglin,Dhakal, Sagar,Lee, Hoonsoo,Cho, Byoung-Kwan,Mo, Changyeun Informa UK (TaylorFrancis) 2017 Food additives & contaminants. Part A. Chemistry, Vol.34 No.2
<P>Milk is a vulnerable target for economically motivated adulteration. In this study, a line-scan high-throughput Raman imaging system was used to authenticate milk powder. A 5W 785nm line laser (240mm long and 1mm wide) was used as a Raman excitation source. The system was used to acquire hyperspectral Raman images in a wave number range of 103-2881cm(-1) from the skimmed milk powder mixed with two nitrogen-rich adulterants (i.e., melamine and urea) at eight concentrations (w/w) from 50 to 10,000 ppm. The powdered samples were put in sample holders with a surface area of 150x100mm and a depth of 2mm for push-broom image acquisition. Varying fluorescence signals from the milk powder were removed using a correction method based on adaptive iteratively reweighted penalised least squares. Image classifications were conducted using a simple thresholding method applied to single-band fluorescence-corrected images at unique Raman peaks selected for melamine (673cm(-1)) and urea (1009cm(-1)). Chemical images were generated by combining individual binary images of melamine and urea to visualise identification, spatial distribution and morphological features of the two adulterant particles in the milk powder. Limits of detection for both melamine and urea were estimated in the order of 50 ppm. High correlations were found between pixel concentrations (i.e., percentages of the adulterant pixels in the chemical images) and mass concentrations of melamine and urea, demonstrating the potential of the high-throughput Raman chemical imaging method for the detection and quantification of adulterants in the milk powder.</P>
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Evaluation of SERS Nanoparticles to Detect Bacillus cereus and Bacillus thuringiensis
홍지화,Jianwei Qin,Jo Ann S. Van Kessel,오미래,Sagar Dhakal,이훈수,황찬송,Diane E. Chan,김동호,조현정,Moon S. Kim 한국농업기계학회 2018 바이오시스템공학 Vol.43 No.4
Purpose: This research evaluated five types of nanoparticles to develop a surface-enhanced Raman spectroscopy (SERS) method for the rapid detection of two Bacillus species (Bacillus cereus and Bacillus thuringiensis) that are commonly found on fresh produce, which can cause food poisoning. Methods: Bacterial concentrations were adjusted to a constant turbidity, and a total of 30 μL of each Bacillus cell suspension was prepared for each nanoparticle. A point-scan Raman system with laser light source of wavelength 785 nm was used to obtain SERS data. Results: There was no qualitative difference in the SERS data of B. cereus and B. thuringiensis for any of the five nanoparticles. Three gold nanoparticles, stabilized in either citrate buffer or ethanol, showed subtle differences in Raman intensities of two Bacillus species at 877.7 cm-1. Conclusions: Among the three types of nanoparticles, the gold nanoparticles stabilized in citrate buffer showed the lowest standard deviation, followed by gold nanoparticles stabilized in ethanol. This result supports the potential application of gold nanoparticles for SERS-based detection of B. cereus and B. thuringiensis.
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Evaluation of SERS Nanoparticles to Detect Bacillus cereus and Bacillus thuringiensis
( Jeehwa Hong ),( Jianwei Qin ),( Jo Ann S. Van Kessel ),( Mirae Oh ),( Sagar Dhakal ),( Hoonsoo Lee ),( Chansong Hwang ),( Diane E. Chan ),( Dongho Kim ),( Hyunjeong Cho ),( Moon S. Kim ) 한국농업기계학회 2018 바이오시스템공학 Vol.43 No.4
Purpose: This research evaluated five types of nanoparticles to develop a surface-enhanced Raman spectroscopy (SERS) method for the rapid detection of two Bacillus species (Bacillus cereus and Bacillus thuringiensis) that are commonly found on fresh produce, which can cause food poisoning. Methods: Bacterial concentrations were adjusted to a constant turbidity, and a total of 30 μL of each Bacillus cell suspension was prepared for each nanoparticle. A point-scan Raman system with laser light source of wavelength 785 nm was used to obtain SERS data. Results: There was no qualitative difference in the SERS data of B. cereus and B. thuringiensis for any of the five nanoparticles. Three gold nanoparticles, stabilized in either citrate buffer or ethanol, showed subtle differences in Raman intensities of two Bacillus species at 877.7 cm-1. Conclusions: Among the three types of nanoparticles, the gold nanoparticles stabilized in citrate buffer showed the lowest standard deviation, followed by gold nanoparticles stabilized in ethanol. This result supports the potential application of gold nanoparticles for SERS-based detection of B. cereus and B. thuringiensis.
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Evaluation of SERS Nanoparticles to Detect Bacillus cereus and Bacillus thuringiensis
Hong, Jeehwa,Qin, Jianwei,Van Kessel, Jo Ann S.,Oh, Mirae,Dhakal, Sagar,Lee, Hoonsoo,Hwang, Chansong,Chan, Diane E.,Kim, Dongho,Cho, Hyunjeong,Kim, Moon S. Korean Society for Agricultural Machinery 2018 바이오시스템공학 Vol.43 No.4
Purpose: This research evaluated five types of nanoparticles to develop a surface-enhanced Raman spectroscopy (SERS) method for the rapid detection of two Bacillus species (Bacillus cereus and Bacillus thuringiensis) that are commonly found on fresh produce, which can cause food poisoning. Methods: Bacterial concentrations were adjusted to a constant turbidity, and a total of $30{\mu}L$ of each Bacillus cell suspension was prepared for each nanoparticle. A point-scan Raman system with laser light source of wavelength 785 nm was used to obtain SERS data. Results: There was no qualitative difference in the SERS data of B. cereus and B. thuringiensis for any of the five nanoparticles. Three gold nanoparticles, stabilized in either citrate buffer or ethanol, showed subtle differences in Raman intensities of two Bacillus species at $877.7cm^{-1}$. Conclusions: Among the three types of nanoparticles, the gold nanoparticles stabilized in citrate buffer showed the lowest standard deviation, followed by gold nanoparticles stabilized in ethanol. This result supports the potential application of gold nanoparticles for SERS-based detection of B. cereus and B. thuringiensis.
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Qin, Jianwei,Kim, Moon S.,Chao, Kuanglin,Schmidt, Walter F.,Dhakal, Sagar,Cho, Byoung-Kwan,Peng, Yankun,Huang, Min Elsevier 2017 Food Control Vol.75 No.-
<P>Subsurface inspection of food and agricultural products is challenging for optical-based sensing techniques due to complex interactions between light and heterogeneous or layered samples. In this study, a method for subsurface food inspection was presented based on a newly developed line-scan spatially offset Raman spectroscopy (SORS) technique. A 785 nm point laser was used as a Raman excitation source. The line-shape SORS data from the sample was collected in a wavenumber range of 0-2815 cm(-1) using a detection module consisting of an imaging spectrograph and a CCD camera. Two layered samples, one by placing a 1 mm thick plastic sheet cut from original container on top of cane sugar and the other by placing a 5 mm thick carrot slice on top of melamine powder, were created to test the subsurface food inspection method. For each sample, a whole set of SORS data was acquired using one CCD exposure in an offset range of 0-36 mm (two sides of the incident laser point) with a spatial interval of 0.07 mm. Raman spectra from the cane sugar under the plastic sheet and the melamine powder under the carrot slice were successfully resolved using self-modeling mixture analysis (SMA) algorithms, demonstrating the potential of the technique for authenticating foods and ingredients through packaging and evaluating internal food safety and quality attributes. The line-scan SORS measurement technique provides a rapid and nondestructive method for subsurface inspection of food safety and quality. Published by Elsevier Ltd.</P>
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