Electron–photon coupling in metal nanostructures has raised a new trend for active plasmonic switch devices in both fundamental understanding and technological applications. However, low sensitivity switches with an on/off ratio less than 5 have restricted applications. In this work, an electrically modulated plasmonic switch based on a surface‐enhanced Raman spectroscopy (SERS) system with a single fivefold stellate polyhedral gold nanoparticle (FSPAuNP) is reported. The reversible switch of the SERS signal shows high sensitivity with an on/off ratio larger than 30. Such a high on/off ratio arises primarily from the plasmonic resonance shift of the FSPAuNP with the incident laser due to the altered free electron density on the nanoparticle under an applied electrochemical potential. This highly sensitive electro‐plasmonic switch may enable further development of plasmonic devices. 相似文献
Reducing the risk of Salmonella contamination in pet food is critical for both companion animals and humans, and its importance is reflected by the substantial increase in the demand for pathogen testing. Accurate and rapid detection of foodborne pathogens improves food safety, protects the public health, and benefits food producers by assuring product quality while facilitating product release in a timely manner. Traditional culture-based methods for Salmonella screening are laborious and can take 5 to 7 days to obtain definitive results. In this study, we developed two methods for the detection of low levels of Salmonella in pet food using real-time PCR: (i) detection of Salmonella in 25 g of dried pet food in less than 14 h with an automated magnetic bead-based nucleic acid extraction method and (ii) detection of Salmonella in 375 g of composite dry pet food matrix in less than 24 h with a manual centrifugation-based nucleic acid preparation method. Both methods included a preclarification step using a novel protocol that removes food matrix-associated debris and PCR inhibitors and improves the sensitivity of detection. Validation studies revealed no significant differences between the two real-time PCR methods and the standard U.S. Food and Drug Administration Bacteriological Analytical Manual (chapter 5) culture confirmation method. 相似文献
The performance of Saponin over different electrolyte-mediated electrokinetic (EK) process for removal of Cr(III) from tannery sludge was assessed. Saponin exhibited maximum Cr(III) removal efficiency, i.e. 67.6–80.75% as compared to other groups of processing fluids. The possible mechanistic approach for the highest removal efficiency of saponin over other electrolytes may be attributed to synchronized effect of micelle formation and subsequent complexation and sorption of chromium ions. The highest electroosmotic flow rate of saponin indicated low electroosmotic resistance during EK process, which validates the observed trend. Therefore, saponin can be considered as a promising electrolyte for EK treatment of tannery sludge.
HBPE of different generations were synthesized using 4-hydroxybenzoic acid and 2,2′,2″-nitrilotriethanol via the A2 + B3 method. The reaction was carried out in a dry nitrogen atmosphere using p-toluene sulfonic acid (p-TSA) as an acid catalyst. The chosen molar ratios of 2,2′,2″-nitrilotriethanol to 4-hydroxybenzoic acid were 1:3, 1:6, and 1:21 for the G1, G2, and G5 generations, respectively. The G5 stage of HBPE was further coupled with acrylic acid to modify the terminal hydroxyl groups. The resulting products were analyzed using 1H NMR, 13C NMR, FTIR spectroscopy, and GPC. Silver nanoparticles were prepared by a reductive technique using HBPEs of the G5 generation as the matrix. XRD and TEM analysis indicated the formation of highly spherical and stable nanosilver in the HBPE. The antibacterial activity of the nanosilver/HBPE was evaluated against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacteria. 相似文献
One of the strategies to overcome the drawbacks of fast charge recombination of a photocatalyst is to develop semiconductor heterostructures. Herein, we report a two-step precipitation-hydrothermal process to create CuFeO2-ZnO heterostructures with different weight percentages of CuFeO2 (0.5, 1, 5, and 10%). Though X-ray diffraction detected the presence of CuFeO2 on ZnO above 5%, Raman spectroscopy could reveal the presence of CuFeO2 phase as low as 0.5 wt%. For all of the compositions, the bandgap of ZnO did not vary (3.15 eV) on forming heterostructures with CuFeO2. The oxidation of methylene blue under sunlight was used to determine the photocatalytic performance of the heterostructures. In comparison to pure ZnO and CuFeO2, CuFeO2-ZnO heterostructures exhibited a better photocatalytic efficiency. Overall, 5 wt% CuFeO2 on ZnO showed 100% degradation with a rate constant of 0.272?±?0.002 min?1, which is 16 times faster than ZnO. Time-resolved photoluminescence analysis indicated a higher lifespan of charge carriers in the 5wt% CuFeO2-ZnO heterostructure (32.3 ns) than that of CuFeO2 (0.85 ns) and ZnO (27.6 ns). The Mott–Schottky flat band potentials of ZnO and CuFeO2 was determined to be -0.82 and 1.17 eV, respectively, revealing the presence of Type I heterostructures. The heterostructures also showed outstanding recyclability, with a degradation rate of 97% even after four cycles. The current study shows the significance of forming p-type CuFeO2 and n-type ZnO heterostructures for enhanced photocatalysis.
The dissolution behaviour of stellite #3 in two oxidizing agents of equivalent acidity namely, permanganic acid (HMnO4) and a mixture of nitric acid and potassium permanganate (NP) was evaluated. The presence of nitrate in the permanganate
formulation was found to reduce its efficiency for oxidizing stellite. Electrochemical polarization and impedance studies
were carried out at 90 °C in NP and HMnO4. The redox potential of both the oxidizing agents favoured transpassive dissolution of chromium from the alloy. In NP, only
the chromium depleted inter-phase boundary was attacked while most of the chromium rich carbide phases were intact. In contrast,
in HMnO4, uniform corrosion of the surface was observed. The impedance response was found to change with duration of exposure. The
nitrate ions in permanganate were found to promote the repassivation of the surface. HMnO4 was found to be a better formulation for dissolving cobalt from the alloy as compared to NP. 相似文献
A comprehensive report on the physical and mechanical properties of titanium boride (TiB), including many recent results that were largely determined in our research, is provided. Fully dense TiB was synthesized by reaction sintering of Ti and TiB2 powders. A bulk nanostructured TiB ceramic material having a microstructure composed of nanosized and interconnected TiB whiskers was created. The TiB produced by this method has properties comparable with that of certain commercial types of silicon nitride. 相似文献