14 research outputs found

    Oxygen Sensing Based on the Yellowing of Newspaper

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    Newspaper is known to turn yellow over time. We show here that this yellowing process is sensitive to oxygen when exposed to UV light, leading to oxygen sensing. Oxygen sensing is critical to many applications, including industrial process control and breath analysis, but the existing oxygen sensors have limitations, especially for breath analysis that operates at 100% humidity. The UV irradiation also triggers fluorescence emission from newspaper, and the fluorescence intensity depends on oxygen concentration, providing an additional oxygen sensing method. Newspaper is stable in ambient air, and reactive to oxygen only with UV activation, which overcomes the instability issue of a typical colorimetric sensor in ambient air. The newspaper oxygen sensor works in 100% relative humidity air, containing various interferents. These unique properties of newspaper promise low cost and reliable oxygen sensing applications

    Mass spectrometric analysis of complex formation between Cu and Hcy.

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    <p><b>A.</b> Chromatogram of Cu and Hcy mixture. <b>B.</b> ESI mass spectrum of Cu and Hcy mixture. The histogram identifies homocysteine (136.0422), Cu-homocysteine (197.9637) homocystine (269.0620), and Cu-homocystine (330.9833), as shown in the schematic structures (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0076209#pone-0076209-t001" target="_blank">Table 1</a>).</p

    Homocysteine (Hcy) induced cell viability changes in and LDH release from human umbilical vein endothelial cells (HUVECs).

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    <p><b>A.</b> MTT assay of cell viability changes as a function of Hcy concentrations. <b>B.</b> Measurement of LDH in media (LDH release) after treatment with concentrations of Hcy. <b>C.</b> Intracellular concentrations of Cu after 24 hrs exposure to concentrations of Hcy in cultures. <b>D.</b> Intracellular concentrations of Hcy after 24 hrs exposure to concentrations of Hcy in cultures. Each data point was obtained from three independent experiments and each experiment contains triplicate samples for each treatment. Values are means ±S.E.M. * or # significantly different from control group and from each other (p<0.05).</p

    Enzymatic assay for changes in cytochrome c oxidase (CCO) activity.

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    <p><b>A.</b> Changes in the CCO activity as a function of Hcy concentrations. <b>B.</b> The effect of Cu pretreatment on Hcy-induced changes in the CCO activity. The treatment protocol and labels are the same as described for <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0076209#pone-0076209-g002" target="_blank">Figure 2</a>. Each data point was obtained from three independent experiments and each experiment contains triplicate samples for each treatment. Values are means ±S.E.M. * significantly different from control group (p<0.05).</p

    Effect of Hcy on mitochondrial membrane potential (ΔΨm) in HUVECs.

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    <p><b>A.</b> JC-1 assay of mitochondrial membrane potential changes as a function of Hcy concentrations. <b>B.</b> The effect of Cu pretreatment on Hcy-induced mitochondrial membrane potential changes. Bar: 100 µm. Each data point was obtained from three independent experiments and each experiment contains triplicate samples for each treatment. Values are means ±S.E.M. * significantly different from control group (p<0.05).</p

    Western blot analysis of Hcy-induced changes in COX17 protein level.

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    <p><b>A.</b> Changes in the COX17 protein level as a function of Hcy concentrations. <b>B.</b> The effect of Cu pretreatment on Hcy-induced changes in the COX17 protein level. The treatment protocol and labels are the same as described for <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0076209#pone-0076209-g002" target="_blank">Figure 2</a>. Semiquantitative analyses based on the density changes of each protein on the blot were obtained from 6 independent blots. Values are means ±S.E.M. * or # significantly different from control group and from each other (p<0.05).</p

    The Estimation of Field-Dependent Conductance Change of Nanopore by Field-Induced Charge in the Translocations of AuNPs-DNA Conjugates

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    Solid-state nanopores have been proven to be a powerful tool for the characterization of individual molecules and nanoparticles. The basic motivation of this technique is to determine the particle size by the conductance change during the translocation of the particle. However, there still has not been a quantitative estimation of the dependence of electric field on the conductance change due to a particle translocation. Here, we present the first observations of the intriguing biphasic and asymmetrical events in the translocations of DNA-modified gold nanoparticles through ∼60 nm nanopores. An electric field-dependent conductance change and quadratic nonlinear electrophoresis were observed as well. Thus, we develop an approximation of the conductance change of nanopore based on induced-charge electrophoresis. The effects of salt concentration, the applied voltage, and particle radius on the conductance change are studied. This study gives a fundamental understanding and provides valuable suggestions to understand the translocation of biomolecular attached metal nanoparticles through nanopores. The results indicate a novel way for direct observation and study of nonlinear electrophoresis of single nanoparticles using nanopore technique as well

    High-Performance Visible-Blind Ultraviolet Photodetector Based on IGZO TFT Coupled with p–n Heterojunction

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    A visible-blind ultraviolet (UV) photodetector was designed based on a three-terminal electronic device of thin-film transistor (TFT) coupled with two-terminal p–n junction optoelectronic device, in hope of combining the beauties of both of the devices together. Upon the uncovered back-channel surface of amorphous indium–gallium–zinc-oxide (IGZO) TFT, we fabricated PEDOT:PSS/SnO<sub><i>x</i></sub>/IGZO heterojunction structure, through which the formation of a p–n junction and directional carrier transfer of photogenerated carriers were experimentally validated. As expected, the photoresponse characteristics of the newly designed photodetector, with a photoresponsivity of 984 A/W at a wavelength of 320 nm, a UV–visible rejection ratio up to 3.5 × 10<sup>7</sup>, and a specific detectivity up to 3.3 × 10<sup>14</sup> Jones, are not only competitive compared to the previous reports but also better than those of the pristine IGZO phototransistor. The hybrid photodetector could be operated in the off-current region with low supply voltages (<0.1 V) and ultralow power dissipation (<10 nW under illumination and ∼0.2 pW in the dark). Moreover, by applying a short positive gate pulse onto the gate, the annoying persistent photoconductivity presented in the wide band gap oxide-based devices could be suppressed conveniently, in hope of improving the response rate. With the terrific photoresponsivity along with the advantages of photodetecting pixel integration, the proposed phototransistor could be potentially used in high-performance visible-blind UV photodetector pixel arrays
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