Measurements of spectral responses for developing fiber-optic pH sensor

In this study, we have fabricated a fiber-optic pH sensor, which is composed of a light source, a pH-sensing probe, plastic optical fibers and a spectrometer, for determining the degree of infection by Helicobacter pylori in the stomach. As pH indicators, phenol red and m-cresol purple are used, and pH liquid solutions are prepared by mixing phenol red or m-cresol purple solutions and various kinds of pH buffer solutions. The light emitted by a light source is guided by plastic optical fibers to the pH liquid solution, and the optical characteristic of a reflected light is changed according to the color variations of the pH indicator in the pH-sensing probe. Therefore, we have measured the intensities and wavelength shifts of the reflected lights, which change according to the color variations of indicators at different pH values, by using a spectrometer for spectral analysis. Also, the relationships between the pH values of liquid solutions and the optical properties of the modulated lights are obtained on the basis of the changes of the colors of indicators.     

Stability analysis of <Emphasis Type="Italic">f</Emphasis>(<Emphasis Type="Italic">R</Emphasis>)-AdS black holes

We study the stability of the f(R)-AdS (Schwarzschild–AdS) black hole obtained from f(R) gravity. In order to resolve the difficulty of solving fourth-order linearized equations, we transform f(R) gravity into scalar–tensor theory by introducing two auxiliary scalars. In this case, the linearized curvature scalar becomes a dynamical scalaron, showing that all linearized equations are second order. Using the positivity of gravitational potentials and S-deformed technique allows us to guarantee the stability of f(R)-AdS black hole if the scalaron mass squared satisfies the Breitenlohner–Freedman bound. This is confirmed by computing quasinormal frequencies of the scalaron for the f(R)-AdS black hole.     

1-Universal binary and ternary Hermitian lattices over imaginary quadratic fields

The Ramanujan Journal - A positive definite Hermitian lattice is said to be 1-universal if it represents all positive definite unary Hermitian lattices, including both free and non-free Hermitian...     

Two‐Dimensional Conducting Polymers: Synthesis and Charge Transport

Current technological advances and prolific endeavors have entrenched two‐dimensional conducting polymers as the rapidly emerging interface across a diversity of functional materials for flexible electronics, sensors, ion‐exchange membranes, biotechnology, catalysis, energy storage, and conversion. Rational design and fabrication of polymeric nanostructures enriched with well‐ordered geometry are appealing and endorse significant impact on their in‐built electrical, optical, and mechanical properties. In particular, recent interest in controlled hierarchical assembly of monomers/oligomers proved the free‐standing sheet‐like structures with exotic features of high conductivity and flexibility. Yet, the ongoing research to make nanometer‐thick polymers suffers from limitations to access large‐area, mechanical stability, and high‐range internal ordering. In this perspective, we focus on the radical approaches that highlight confinement‐entitled features of two‐dimensional polymeric materials correlating to their interface or template‐assisted synthesis, structure–property relationship, charge transport properties, and future scopes for relevant practical enactments. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1169–1176     

Detection of pyridaben residue levels in hot pepper fruit and leaves by liquid chromatography–tandem mass spectrometry: effect of household processes

Following quick, easy, cheap, effective, rugged and safe (QuEChERS) and LC/MS/MS analysis, pyridaben residual levels were determined in unprocessed and processed hot pepper fruit and leaves. The linearities were satisfactory with determination coefficients (R²) in excess of 0.995 in processed and unprocessed pepper fruit and leaves. Recoveries at various concentrations were 79.9–105.1% with relative standard deviations ≤15%. The limits of quantitation of 0.003–0.012 mg/kg were very low compared with the maximum residue limits (2–5 mg/kg) set by the Ministry of Food and Drug Safety, Republic of Korea. The effects of various household processes, including washing, blanching, frying and drying under different conditions (water volume, blanching time and temperature) on residual concentrations were evaluated. Both washing and blanching (in combination with high water volume and time factor) significantly reduced residue levels in hot pepper fruit and leaves compared with other processes. In sum, the developed method was satisfactory and could be used to accurately detect residues in unprocessed and processed pepper fruit and leaves. It is recommended that pepper fruit/leaves be blanched after washing before being consumed to protect consumers from the negative health effects of detected pesticide residues. Copyright © 2014 John Wiley & Sons, Ltd.     

Brain tumor diagnostic model and dietary effect based on extracellular vesicle microbiome data in serum

The human microbiome has been recently associated with human health and disease. Brain tumors (BTs) are a particularly difficult condition to directly link to the microbiome, as microorganisms cannot generally cross the blood–brain barrier (BBB). However, some nanosized extracellular vesicles (EVs) released from microorganisms can cross the BBB and enter the brain. Therefore, we conducted metagenomic analysis of microbial EVs in both serum (152 BT patients and 198 healthy controls (HC)) and brain tissue (5 BT patients and 5 HC) samples based on the V3–V4 regions of 16S rDNA. We then developed diagnostic models through logistic regression and machine learning algorithms using serum EV metagenomic data to assess the ability of various dietary supplements to reduce BT risk in vivo. Models incorporating the stepwise method and the linear discriminant analysis effect size (LEfSe) method yielded 12 and 29 significant genera as potential biomarkers, respectively. Models using the selected biomarkers yielded areas under the curves (AUCs) >0.93, and the model using machine learning resulted in an AUC of 0.99. In addition, Dialister and [Eubacterium] rectale were significantly lower in both blood and tissue samples of BT patients than in those of HCs. In vivo tests showed that BT risk was decreased through the addition of sorghum, brown rice oil, and garlic but conversely increased by the addition of bellflower and pear. In conclusion, serum EV metagenomics shows promise as a rich data source for highly accurate detection of BT risk, and several foods have potential for mitigating BT risk.Subject terms: Diagnostic markers, Machine learning     

Bright flexible organic light-emitting devices on copy paper substrates

We have developed flexible top emission organic light-emitting devices (OLEDs) using copy paper substrates. Poly-2-chloro-p-xylylene and SiO₂ buffer layers were coated on the copy paper for protecting the water absorption and improving the barrier and morphological characteristics. Sputtered Ni and thermally evaporated Ca/Ag films were used as anode and semitransparent cathode, respectively. The electrical conduction, luminance, and efficiency characteristics of the copy paper-based flexible OLEDs were investigated. The SiO₂ buffer layer was critically important in obtaining the high performance devices. The device exhibited a high luminance of 2200 cd/m² at a driving voltage of 13 V.     

High energy and power density of self-grown CuS@Cu2O core-shell supercapattery positrode

Journal of Solid State Electrochemistry - A self-grown copper sulfide@copper oxide (CuS@Cu2O) positrode synthsis by a hydrothermal method followed by 2&nbsp;h of air annealing method (at...