BIO-SENSING SENSITIVITY OF A NANOPARTICLE BASED ULTRAVIOLET PHOTODETECTOR

2011 ◽  
Vol 20 (03) ◽  
pp. 505-513 ◽  
Author(s):  
CHRISTOPHER SHING ◽  
LIQIAO QIN ◽  
SHALYA SAWYER
Keyword(s):  
Aluminum Gallium Nitride ◽  
Environmental Changes ◽  
Uv Light ◽  
Poly Vinyl Alcohol ◽  
Light Illumination ◽  
Zno Nanoparticle ◽  
Silicon Photodiode ◽  
E Coli ◽  
Spectrally Selective ◽  
Sensing Sensitivity

Bio-sensing sensitivity of a spectrally selective nanoparticle based ultraviolet (UV) photodetector is characterized in comparison to a silicon photodiode and a photomultiplier tube (PMT). The nanoparticle based photodetector is comprised of poly-vinyl alcohol (PVA) coated zinc-oxide ( ZnO ) nanoparticles deposited on an aluminum-gallium-nitride ( AlGaN ) epitaxially grown substrate. The sensitivity was determined by measuring the fluorescence intensity of the native fluorophore, tryptophan, in Escherichia coli (E-coli, ATCC-25922) cells. Tryptophan intrinsically fluoresces with a peak at 340 nm under 280 nm UV light illumination. It is shown that this detector can sense the concentration of E-coli to 2.5 × 108 cfu/mL while the silicon photodiode cannot detect the intrinsic fluorescence at all. Nevertheless, the PMT outperformed the ZnO nanoparticle- AlGaN substrate based photodetector with the ability to sense E-coli concentrations to 3.91 × 106 cfu/mL. However, because PMT based systems are commonly limited by high dark current, susceptible to environmental changes, sensitive to ambient light, are not spectrally selective and have high power consumption, biological detection systems comprised of these ZnO nanoparticle- AlGaN substrate based photodetectors can be more effective for near real time characterization of potential bacterial contamination.

Room-Temperature ZnO Nanoparticle Ethanol Gas Sensors under UV Illumination

2012 ◽  
Vol 486 ◽  
pp. 39-43 ◽  
Author(s):  
S.P. Chang
Keyword(s):  
Gas Sensor ◽  
Gas Sensors ◽  
Spin Coating ◽  
Room Temperature ◽  
Uv Light ◽  
Light Illumination ◽  
Zno Nanoparticle ◽  
Uv Illumination ◽  
Potential Applications ◽  
Nanoparticle Film

A zinc oxide (ZnO) nanoparticle gas sensor was formed by spin coating. We annealed the film at 400, 600, and 800°C for 1 h in air to create a gas sensor. The responses of the gas sensor to ethanol under UV light illumination were investigated. We found that the ZnO nanoparticle film annealed at 800°C had the highest sensitivity. This can be attributed to the fact that the defects of ZnO nanoparticle film annealed at 800°C are considerably more than those for the film annealed at other temperatures. This study demonstrates that ZnO nanoparticles have potential applications as room-temperature ethanol sensors.

scholarly journals UV Illumination Room-Temperature ZnO Nanoparticle Ethanol Gas Sensors

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Sheng-Po Chang ◽  
Kuan-Yu Chen
Keyword(s):  
Gas Sensor ◽  
Gas Sensors ◽  
Room Temperature ◽  
Uv Light ◽  
Light Illumination ◽  
Zno Nanoparticle ◽  
Uv Illumination ◽  
Potential Applications ◽  
Film Annealing ◽  
Nanoparticle Film

Zinc oxide (ZnO) nanoparticle gas sensor was formed by spin coating. We annealed the film at 400, 600, and 800°C for 1 hour in air to make gas sensor. The responses of gas sensor to ethanol with UV light illumination were investigated. It could be observed that the ZnO nanoparticle film annealing at 800°C has the highest sensitivity. It can be attributed to the defects of ZnO nanoparticle film annealing at 800°C much more than other annealing temperatures. The study shows that the ZnO nanoparticles have potential applications as RT ethanol sensors.

Probing the Dynamic Self-Assembly Behaviour of Photoswitchable Wormlike Micelles in Real Time

2018 ◽  
Author(s):  
Elaine A. Kelly ◽  
Judith E. Houston ◽  
Rachel Evans
Keyword(s):  
Real Time ◽  
Absorption Spectroscopy ◽  
Self Assembly ◽  
Uv Light ◽  
Wormlike Micelles ◽  
Tetraethylene Glycol ◽  
Light Illumination ◽  
First Time ◽  
Dependent Processes

Understanding the dynamic self-assembly behaviour of azobenzene photosurfactants (AzoPS) is crucial to advance their use in controlled release applications such as<i></i>drug delivery and micellar catalysis. Currently, their behaviour in the equilibrium <i>cis-</i>and <i>trans</i>-photostationary states is more widely understood than during the photoisomerisation process itself. Here, we investigate the time-dependent self-assembly of the different photoisomers of a model neutral AzoPS, <a>tetraethylene glycol mono(4′,4-octyloxy,octyl-azobenzene) </a>(C<sub>8</sub>AzoOC<sub>8</sub>E<sub>4</sub>) using small-angle neutron scattering (SANS). We show that the incorporation of <i>in-situ</i>UV-Vis absorption spectroscopy with SANS allows the scattering profile, and hence micelle shape, to be correlated with the extent of photoisomerisation in real-time. It was observed that C<sub>8</sub>AzoOC<sub>8</sub>E<sub>4</sub>could switch between wormlike micelles (<i>trans</i>native state) and fractal aggregates (under UV light), with changes in the self-assembled structure arising concurrently with changes in the absorption spectrum. Wormlike micelles could be recovered within 60 seconds of blue light illumination. To the best of our knowledge, this is the first time the degree of AzoPS photoisomerisation has been tracked <i>in</i><i>-situ</i>through combined UV-Vis absorption spectroscopy-SANS measurements. This technique could be widely used to gain mechanistic and kinetic insights into light-dependent processes that are reliant on self-assembly.

scholarly journals Detecting Bacterial Biofilms Using Fluorescence Hyperspectral Imaging and Various Discriminant Analyses

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 2213
Author(s):  
Ahyeong Lee ◽  
Saetbyeol Park ◽  
Jinyoung Yoo ◽  
Jungsook Kang ◽  
Jongguk Lim ◽  
...  
Keyword(s):  
Discriminant Analysis ◽  
Hyperspectral Imaging ◽  
Food Processing ◽  
Nearest Neighbor ◽  
Hyperspectral Image ◽  
Uv Light ◽  
Hyperspectral Images ◽  
K Nearest Neighbor ◽  
E Coli ◽  
Discriminant Analyses

Biofilms formed on the surface of agro-food processing facilities can cause food poisoning by providing an environment in which bacteria can be cultured. Therefore, hygiene management through initial detection is important. This study aimed to assess the feasibility of detecting Escherichia coli (E. coli) and Salmonella typhimurium (S. typhimurium) on the surface of food processing facilities by using fluorescence hyperspectral imaging. E. coli and S. typhimurium were cultured on high-density polyethylene and stainless steel coupons, which are the main materials used in food processing facilities. We obtained fluorescence hyperspectral images for the range of 420–730 nm by emitting UV light from a 365 nm UV light source. The images were used to perform discriminant analyses (linear discriminant analysis, k-nearest neighbor analysis, and partial-least squares discriminant analysis) to identify and classify coupons on which bacteria could be cultured. The discriminant performances of specificity and sensitivity for E. coli (1–4 log CFU·cm−2) and S. typhimurium (1–6 log CFU·cm−2) were over 90% for most machine learning models used, and the highest performances were generally obtained from the k-nearest neighbor (k-NN) model. The application of the learning model to the hyperspectral image confirmed that the biofilm detection was well performed. This result indicates the possibility of rapidly inspecting biofilms using fluorescence hyperspectral images.

Photosensitive PVA Polarizing Film

2006 ◽  
Vol 11-12 ◽  
pp. 351-354
Author(s):  
Jie Wei ◽  
Xiao Mei Ji ◽  
Xiao Wang ◽  
Xiao Ming Dong
Keyword(s):  
Vinyl Alcohol ◽  
Uv Light ◽  
Light Transmittance ◽  
Poly Vinyl Alcohol ◽  
X Ray ◽  
Series Of Experiments ◽  
Uv Visible ◽  
Crystallization Degree

In order to analyze the polarization of Poly(vinyl alcohol) (PVA) film, both the polarizing film and polarizing film exposed to UV light were prepared and investigated by X-ray diffractometer (XRD) and polarized UV-Visible Spectrometer. Through a series of experiments, it was found that the crystallization degree of the unirradiated PVA film was higher than that of the UV-irradiated PVA film. Furthermore, the transmittance of both unirradiated PVA film and UV-irradiated PVA film was selective, different wavelength and different polarizing angles parallelism different light transmittance.

Phylogeny of Immunity, edited by R. T. Smith, M.D., P. A. Miescher, M.D., and R. A. Good, M.D. Gainesville, Florida: University of Florida Press, 1966, 276 pp. $15.00

PEDIATRICS ◽  
1968 ◽  
Vol 41 (4) ◽  
pp. 862-862
Author(s):  
Fred S. Rosen
Keyword(s):  
Environmental Changes ◽  
University Of Florida ◽  
E Coli ◽  
Immune Mechanisms ◽  
Biological Interest

It has been stated that the adaptability of higher organisms to environmental changes and stress is most vividly manifested by the organization of mind, the detoxifying versatility of liver, and the responsiveness of immune mechanisms. Thus, the evolutionary and developmental aspects of any of these systems are of broad biological interest, beyond the realm of the molecular biologists and their now incisive comprehension of E. coli. In two successive volumes the editors have assembled a distinguished collection of presentations in the balmy isolation of Sanibel Island, Florida.

Destruction of Pollutants and Microorganisms in Water by UV Light and Hydrogen Peroxide

1992 ◽  
Vol 27 (1) ◽  
pp. 57-68 ◽  
Author(s):  
D.W. Sundstrom ◽  
B.A. Weir ◽  
T. A. Barber ◽  
H. E. Klei
Keyword(s):  
Hydrogen Peroxide ◽  
Organic Compounds ◽  
Chemical Structure ◽  
Uv Light ◽  
Liquid Films ◽  
Strong Interactions ◽  
Order Kinetic ◽  
E Coli ◽  
Order Kinetic Model ◽  
Catalyzed Oxidation

Abstract This project investigated the destruction of organic compounds and microorganisms in water by ultraviolet catalyzed oxidation using hydrogen peroxide as the oxidizing agent. The combination of UV light and hydrogen peroxide was effective in decomposing all of the organic compounds studied. The rates of destruction increased with increasing peroxide concentration and UV light intensity, and were highly dependent on chemical structure. The destruction of mixtures of organic compounds showed strong interactions between reacting components. The inactivation of E. coli and B. subtilis spores by UV light and/or hydrogen peroxide was studied in flat plate reactors. By using thin liquid films, the combination of UV light and peroxide greatly increased the rates of inactivation of both microorganisms. The results were correlated by a mixed second order kinetic model.

Effects of Water Source, Dilution, Storage, and Bacterial and Fecal Loads on the Efficacy of Electrolyzed Oxidizing Water for the Control of Escherichia coli O157:H7

2004 ◽  
Vol 67 (7) ◽  
pp. 1377-1383 ◽  
Author(s):  
S. M. L. STEVENSON ◽  
S. R. COOK ◽  
S. J. BACH ◽  
T. A. McALLISTER
Keyword(s):  
Escherichia Coli ◽  
Bactericidal Activity ◽  
Storage Temperature ◽  
Uv Light ◽  
Tap Water ◽  
Organic Matter Content ◽  
Water Source ◽  
Deionized Water ◽  
Escherichia Coli O157 ◽  
E Coli

To evaluate the potential of using electrolyzed oxidizing (EO) water for controlling Escherichia coli O157:H7 in water for livestock, the effects of water source, electrolyte concentration, dilution, storage conditions, and bacterial or fecal load on the oxidative reduction potential (ORP) and bactericidal activity of EO water were investigated. Anode and combined (7:3 anode:cathode, vol/vol) EO waters reduced the pH and increased the ORP of deionized water, whereas cathode EO water increased pH and lowered ORP. Minimum concentrations (vol/vol) of anode and combined EO waters required to kill 104 CFU/ml planktonic suspensions of E. coli O157:H7 strain H4420 were 0.5 and 2.0%, respectively. Cathode EO water did not inhibit H4420 at concentrations up to 16% (vol/vol). Higher concentrations of anode or combined EO water were required to elevate the ORP of irrigation or chlorinated tap water compared with that of deionized water. Addition of feces to EO water products (0.5% anode or 2.0% combined, vol/vol) significantly reduced (P &lt; 0.001) their ORP values to &lt;700 mV in all water types. A relationship between ORP and bactericidal activity of EO water was observed. The dilute EO waters retained the capacity to eliminate a 104 CFU/ml inoculation of E. coli O157:H7 H4420 for at least 70 h regardless of exposure to UV light or storage temperature (4 versus 24°C). At 95 h and beyond, UV exposure reduced ORP, significantly more so (P &lt; 0.05) in open than in closed containers. Bactericidal activity of EO products (anode or combined) was lost in samples in which ORP value had fallen to ≤848 mV. When stored in the dark, the diluted EO waters retained an ORP of &gt;848 mV and bactericidal efficacy for at least 125 h; with refrigeration (4°C), these conditions were retained for at least 180 h. Results suggest that EO water may be an effective means by which to control E. coli O157:H7 in livestock water with low organic matter content.

Optic and Piezoelectric Coupling in the Sol-Gel PLZT Electroceramics

2012 ◽  
Vol 730-732 ◽  
pp. 129-134
Author(s):  
Lucjan Kozielski ◽  
Malgorzata Plonska
Keyword(s):  
Uv Light ◽  
Sol Gel ◽  
Light Illumination ◽  
Piezoelectric Effects ◽  
Piezoelectric Coupling ◽  
Wireless Device ◽  
Organometallic Precursors ◽  
Gain Adjustment ◽  
Piezoelectric Transformers ◽  
Sintering Method

PZT ceramic system with presence of La contents, have been proposed and prepared using sol gel sintering method for practical application of photostriction, which is the superposition of photovoltaic and piezoelectric effects. Such a ceramics produced by conventional mixing oxide method does not exhibit photostrictive properties due to the defects and inhomogeneous distribution of grains and pores. In this study, an investigated lanthanium(III) doped PZT ceramics were obtained by sol-gel technique from the organometallic precursors. It was found that fabricated material were effective in the enhancement of photovoltaic and photostrictive properties. Consequently, lanthanium influence deviation of piezoelectric parameters were studied as a function UV light illumination. For the determination lighting dependancy of the transformation parameters the resonant and antiresonant method was implemented. The improved Piezoelectric Transformer structure successfully changed gain characteristics proportionally to light intensity. The authors invention of a light driven output gain adjustment in Piezoelectric Transformers (PT) yields a novel “smart” multifunctional wireless device. This new created application area can be utilized in self-adopting shutters in photo cameras due to improved sensitivity to surrounding illumination conditions.

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