CO-sensing properties of a NASICON-based gas sensor attached with Pt mixed with Bi2O3 as a sensing electrode

NASICON (Na3Zr2Si2PO12)-based gas sensors capable of detecting various gases (CO2, NO2, Cl2, VOC and so on) have so far been developed by many researchers. In this study, planar-type gas sensors using a NASICON disc attached with Pt mixed with Bi2O3 as a sensing electrode (Pt(nBi2O3), n (0.01?30): the amount of Bi2O3 addition (wt%)) and Pt as a reference electrode were fabricated, and their sensing properties to CO and H2 were examined in the operating temperature range of 25?300 °C in dry and wet air. The sensors obtained were denoted as Pt(nBi2O3)/Pt. All Pt(nBi2O3)/Pt sensors fabricated responded to CO at all operating temperatures tested, and the magnitude of CO response increased with a decrease in the operating temperature. In addition, the magnitude of CO response largely depended on the additive amounts of Bi2O3 to the Pt sensing electrode. The increase in the additive amount of Bi2O3 to the Pt sensing electrode (0.01 ? n ? 1) enhanced markedly the magnitude of CO response, 90% response time and CO selectivity against H2. The Pt(1Bi2O3)/Pt sensor showed a linear relationship between the CO response and the logarithm of CO concentration (1?3000 ppm) in dry air at 25 °C and the CO selectivity against H2 was enhanced in wet air, in comparison with those observed in dry air. The interfacial layer, which was formed between the NASICON and the Pt(1Bi2O3) electrode, was suggested to play an important role in improving of the CO-sensing properties

Effect of AQP9 Expression in Androgen-Independent Prostate Cancer Cell PC3

It is known that aquaporin 9 (AQP9) in the prostate was strictly upregulated by androgen and may represent a novel therapeutic target for several cancers, but whether AQP9 plays a role in the regulation of androgen-independent prostate cancer still remains unclear. In the present study, AQP9 was determined in prostate cancer and adjacent cancer tissues; AQP9-siRNA was applied to silencing AQP9 in androgen-independent prostate cancer cell PC3 cell line. Western blot and flow cytometry analysis were employed to detect changes in related-function of control and AQP9-siRNA groups. The results showed that AQP9 is significantly induced in cancer tissues than that in adjacent cancer tissues. Moreover, knockdown of AQP9 in PC3 androgen-independent prostate cancer cell prostate cancer cells increased inhibition rates of proliferation. In addition, knockdown of AQP9 resulted in a significant decrease in the expression of the Bcl-2 and with a notable increase in the expression of Bax and cleaved caspase 3, indicated that AQP9 knockdown promoted apoptosis in prostate cancer cells. From wound healing assay and matrigel invasion, we suggested that AQP9 expression affects the motility and invasiveness of prostate cancer cells. Moreover, In order to explore the pathway may be involved in AQP9-mediated motility and invasion of prostate cancer cells, the phosphorylation of ERK1/2 was significant suppressed in AQP9 siRNA-transfected cells compared with that in control cells, suggesting that AQP9 is involved in the activation of the ERK pathway in androgen-independent prostate cancer cells

Double-Shell Architectures of ZnFe₂O₄ Nanosheets on ZnO Hollow Spheres for High-Performance Gas Sensors

In this study, double-shell composites consisting of inner ZnO hollow microspheres (ZHS) surrounded by outer ZnFe₂O₄ nanosheets were successfully synthesized. The growth of the ultrathin ZnFe₂O₄ nanosheets (∼10 nm) on the ZHS outer surface was carried out at room temperature via solution reactions in order to generate a double-shell configuration that could provide a large surface area. As a proof-of-concept demonstration of the design, a comparative sensing investigation between the sensors based on the as-obtained ZnO/ZnFe₂O₄ composites and its two individual components (ZnO hollow spheres and ZnFe₂O₄ nanosheets) was performed. As expected, the response of the ZnFe₂O₄-decorated ZnO composites to 100 ppm acetone was about 3 times higher than that of initial ZnO microspheres. Moreover, a dramatic reduction of response/recover time has been achieved at different operating temperature. Such favorable sensing performances endow these ZnO/ZnFe₂O₄ heterostructures with a potential application in gas sensing

Nanosheet-Assembled ZnFe₂O₄ Hollow Microspheres for High-Sensitive Acetone Sensor

Semiconductor oxides with hierarchically hollow architecture can provide significant advantages as sensing materials for gas sensors by facilitating the diffusion of target gases. Herein, we develop a facile template-free solvothermal strategy combined with the subsequent thermal treatment process toward the successful synthesis of novel ZnFe₂O₄ hollow flower-like microspheres. The images of electron microscopy unambiguously indicated that the ZnFe₂O₄ nanosheets with thickness of around 20 nm assembled hierarchically to form the unique flower-like architecture. As a proof-of-concept demonstration of the function, the as-prepared product was utilized as sensing material for gas sensor. Significantly, in virtue of the porous shell structure, hollow interior, and large surface area, ZnFe₂O₄ hierarchical microspheres exhibited high response, excellent cyclability, and long-term stability to acetone at the operating temperature of 215 °C

Enhanced Gas Sensing Properties of SnO₂ Hollow Spheres Decorated with CeO₂ Nanoparticles Heterostructure Composite Materials

CeO₂ decorated SnO₂ hollow spheres were successfully synthesized via a two-step hydrothermal strategy. The morphology and structures of as-obtained CeO₂/SnO₂ composites were analyzed by various kinds of techniques. The SnO₂ hollow spheres with uniform size around 300 nm were self-assembled with SnO₂ nanoparticles and were hollow with a diameter of about 100 nm. The CeO₂ nanoparticles on the surface of SnO₂ hollow spheres could be clearly observed. X-ray photoelectron spectroscopy results confirmed the existence of Ce³⁺ and the increased amount of both chemisorbed oxygen and oxygen vacancy after the CeO₂ decorated. Compared with pure SnO₂ hollow spheres, such composites revealed excellent enhanced sensing properties to ethanol. When the ethanol concentration was 100 ppm, the sensitivity of the CeO₂/SnO₂ composites was 37, which was 2.65-times higher than that of the primary SnO₂ hollow spheres. The sensing mechanism of the enhanced gas sensing properties was also discussed

Highly Enhanced Sensing Properties for ZnO Nanoparticle-Decorated Round-Edged α‑Fe₂O₃ Hexahedrons

ZnO/α-Fe₂O₃ composites built from plenty of ZnO nanoparticles decorated on the surfaces of uniform round-edged α-Fe₂O₃ hexahedrons were successfully prepared via a facile solvothermal method. Various techniques were employed to obtain the crystalline and morphological characterization of the as-prepared samples. In addition, a comparative sensing performance investigation between the two kinds of sensing materials clearly demonstrated that the sensing properties of ZnO/α-Fe₂O₃ composites were substantially enhanced compared with those of the single α-Fe₂O₃ component, which manifest the superiority of the ZnO decoration as we expected. For instance, the response of ZnO/α-Fe₂O₃ composites to 100 ppm acetone is ∼30, which is ∼3.15-fold higher than that of primary α-Fe₂O₃ hexahedrons. The synergetic effect is believed to be the source of the improvement of gas-sensing properties