Solution-Processed Ga₂O₃ Films via Thermal Annealing for Solar Blind Ultraviolet Photovoltaic Photodetectors with High Photoresponsivity and Fast Response

In this work, a strategy that enhances the decomposition of organic compounds and suppresses oxygen defects in solution-processed Ga2O3 films is proposed to fabricate high-performance Ga2O3 solar blind ultraviolet (SBUV) photodetectors. The photodetector based on the Ga2O3 film annealed at 800 °C exhibits a high response of ∼17 ms and a high photoresponsivity of ∼15.4 mA/W at a 0 V bias. Through a comparison of the photoelectric properties among the detectors fabricated on the films annealed at high temperature (800 °C) and low temperature (500 or 600 °C), the device based on the Ga2O3 film annealed at higher temperature presents higher photoresponsivity and faster response. The improvement in device performance can be attributed to the decrease in the concentration of organic matter and the density of oxygen defects in the Ga2O3 photosensitive layer after high-temperature annealing. The method proposed in this work can give reference to the fabrication of high-responsivity and fast-response SBUV detectors based on solution-processed films

5.7 GHz Ultrasensitive Shear Horizontal-Surface Acoustic Wave Humidity Sensor Based on LiNbO₃/SiO₂/SiC Heterostructures with a Sensitive Layer of Polyethyleneimine-SiO₂ Nanocomposites

Humidity sensing and water molecule monitoring have become hot research topics attributed to their potential applications in monitoring breathing/physiological conditions of humans, air conditioning in greenhouses, and soil moisture in agriculture. However, there is a huge challenge for highly sensitive and precision humidity detection with wireless and fast responsive capabilities. In this work, a hybrid/synergistic strategy was proposed using a LiNbO3/SiO2/SiC heterostructure to generate shear-horizontal (SH) surface acoustic waves (SAWs) and using a nanocomposite of polyethylenimine-silicon dioxide nanoparticles (PEI-SiO2 NPs) to form a sensitive layer, thus achieving an ultrahigh sensitivity of SAW humidity sensors. Ultrahigh frequencies (1∼15 GHz) of SAW devices were obtained on a high-velocity heterostructure of LiNbO3/SiO2/SiC. Among the multimodal wave modes, we selected SH waves for humidity sensing and achieved a high mass-sensitivity of 5383 MHz · mm2 · μg–1. With the PEI-SiO2 NP composite as the sensitive layer, an ultrahigh sensitivity of 2.02 MHz/% RH was obtained, which is two orders of magnitude higher than those of the conventional SAW humidity sensors (∼202.5 MHz frequency) within a humidity range of 20–80% RH

Physiological and Biochemical Characterization of a Novel Nicotine-Degrading Bacterium <i>Pseudomonas geniculata</i> N1

<div><p>Management of solid wastes with high nicotine content, such as those accumulated during tobacco manufacturing, poses a major challenge, which can be addressed by using bacteria such as <i>Pseudomonas</i> and <i>Arthrobacter</i>. In this study, a new species of <i>Pseudomonas geniculata</i>, namely strain N1, which is capable of efficiently degrading nicotine, was isolated and identified. The optimal growth conditions for strain N1 are a temperature of 30°C, and a pH 6.5, at a rotation rate of 120 rpm min⁻¹ with 1 g l⁻¹ nicotine as the sole source of carbon and nitrogen. Myosmine, cotinine, 6-hydroxynicotine, 6-hydroxy-N-methylmyosmine, and 6-hydroxy-pseudooxynicotine were detected as the five intermediates through gas chromatography-mass and liquid chromatography-mass analyses. The identified metabolites were different from those generated by <i>Pseudomonas putida</i> strains. The analysis also highlighted the bacterial metabolic diversity in relation to nicotine degradation by different <i>Pseudomonas</i> strains.</p></div

Utilizations of carbon sources by strain N1.

<p>Notes: -, negative reaction; +, positive reaction; w, weak positive reaction.</p

ESI-TOF-MS analysis of the metabolites of nicotine degradation by strain N1.

<p>ESI-TOF-MS analysis of the intermediates of nicotine degradation by “resting cell reactions” of strain <i>P. geniculata</i> N1. The molecular ion peaks ([M+H]⁺) of 6-hydroxynicotine (6HN, C₁₀H₁₄N₂O), 6-hydroxy-<i>N</i>-methymyosime (6HMM, C₁₀H₁₂N₂O), 6-hydroxy-pseudooxynicotine (6HPON, C₁₀H₁₄N₂O₂), and 2,6-dihydroxypseudooxynicotine (2,6HPON, C₁₀H₁₄N₂O₃), were shown at <i>m</i>/<i>z</i> 179.1182, 177.1021, 195.1135, and 211.1442 respectively.</p

Phylogenetic tree of 16S rRNA from 35 different strains.

<p>The phylogenetic tree is constructed using the molecular evolutionary genetics analysis tool (MEGA 4.1) by neighbor joining (NJ) method <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0084399#pone.0084399-Kumar1" target="_blank">[19]</a>. The repeated bootstrapping for 1,000 times was performed.</p

Biochemical and physiological characteristics of strain N1.

<p>Notes: −, negative reaction; +, positive reaction.</p

Optimization of cell growth of strain N1 in different conditions.

<p><b>A</b>, Growth of <i>Pseudomonas geniculata</i> strain N1 at different temperatures; <b>B</b>, Nicotine degradation by strain N1 at different temperatures; <b>C</b>, Growth of strain N1 at different pH values; <b>D</b>, Nicotine degradation by strain N1 at different pH values; <b>E</b>, Growth of strain N1 at different original concentrations of nicotine; <b>F</b>, Nicotine degradation by strain N1 at different original concentrations of nicotine; <b>G</b>, Growth of strain N1 at different rotation rates; <b>H</b>, Nicotine degradation by strain N1 at different rotation rates.</p