Label free detection of multiple trace antibiotics with SERS substrates and independent components analysis.

Surface enhanced Raman spectroscopy (SERS) has been widely studied and recognized as a powerful label-free technique for trace chemical analysis. However, its drawback in simultaneously identifying several molecular species has greatly limited its real-world applications. In this work, we reported a combination between SERS and independent component analysis (ICA) to detect several trace antibiotics which are commonly used in aquacultures, including malachite green, furazolidone, furaltadone hydrochloride, nitrofurantoin, and nitrofurazone. The analysis results indicate that the ICA method is highly effective in decomposing the measured SERS spectra. The target antibiotics could be precisely identified when the number of components and the sign of each independent component loading were properly optimized. With SERS substrates, the optimized ICA can identify trace molecules in a mixture at a concentration of 10-6 M achieving the correlation values to the reference molecular spectra of 71-98%. Furthermore, measurement results obtained from a real-world sample demonstration could also be recognized as an important basis to suggest this method is promising for monitoring antibiotics in a real aquatic environment.

Influence of an Annealing Temperature in a Vacuum Atmosphere on the Physical Properties of Indium Tin Oxide Nanorod Films.

In the present study, indium tin oxide (ITO) nanorod films were produced by usage of ion-assisted electron-beam evaporation with a glancing angle deposition technique. The as-produced ITO nanorod films were annealed in the temperature range of 100-500 °C for two hours in a vacuum atmosphere. The as-produced ITO nanorod films exhibited (222) and (611) preferred orientations from the X-ray diffraction pattern. After vacuum annealing at 500 °C, the ITO nanorod films demonstrated many preferred orientations and the improvement of film crystallinity. The sheet resistance of the as-produced ITO nanorod films was 11.92 Ω/ and was found to be 13.63 Ω/ by annealing at 500 °C. The as-produced and annealed ITO nanorod films had a rod diameter of around 80 nm and transmittance in a visible zone of around 90%. The root mean square roughness of the as-produced ITO nanorod film's surface was 5.49 nm, which increased to 13.77 nm at an annealing temperature of 500 °C. The contact angle of the as-produced ITO nanorod films was 110.9° and increased to 116.5° after annealing at 500 °C.

Influence of Annealing Temperature on Mechanical and Wetting Properties of ß-FeSi2 Films Built Using Facing-Targets Direct-Current Sputtering.

In this research, ß-FeSi2 films were formed on Si(111) wafer substrates via the utilization of facingtargets direct-current sputtering (FTDCS). The sputtering pressure was set at 1.33×10-1 Pa and the substrate temperature was maintained at 600 °C. After formation, the as-formed ß-FeSi2 films were transferred to the annealing system and annealed for two hours in a vacuum at 200, 400, and 600 °C. The peaks of the Raman line were located at positions of 194 and 247 cm-1, which affirmed the formation of the ß phase for the as-produced FeSi2 films. These peak positions were not changed significantly by annealing. FESEM imagery of the as-formed ß-FeSi2 films exhibits a large amount of crystallite with an average grain size of 114.11 nm, including many grain boundaries and a porous area. After annealing, the porosity of the film surface was diminished and grain size was expanded. The rms roughness of the as-formed ß-FeSi2 films was 2.02 nm, which changed slightly after annealing. The average contact angle between the water droplet and as-formed ß-FeSi2 film surface was found to be 93.25°. This result showed that the surface of the unannealed ß-FeSi2 films was hydrophobic. The average contact angle value decreased to 82.15° at an annealing temperature of 600 °C. The hardness of the ß-FeSi2 film surface was 37.55 GPa and 64.88 GPa in cases of non-annealing and annealing temperatures of 600 °C, respectively.

Effect of Annealing on Surface Morphology and Wettability of NC-FeSi2 Films Produced via Facing-Target Direct-Current Sputtering.

Nanocrystalline iron disilicide (NC-FeSi2) films were created at room temperature by facing-target direct current sputtering. The NC-FeSi2 films were annealed at different temperatures of 300 °C, 600 °C, and 900 °C under high vacuum for 2 hours. XRD results of the as-created NC-FeSi2 films after annealing at 300 °C showed a broad peak at 2 ranging from 40° to 50°. NC-FeSi2 films annealed at 600 and 900 °C consisted of several preferred orientations with improved crystallinity. Peaks of Raman lines for unannealed and annealed NC-FeSi2 films were observed at approximately 176 and 232 cm-1, respectively. Based on FESEM micrographs in plane view, unannealed NC-FeSi2 films were composed of many small uniform crystallites with diameters of 5-7 nm. At an annealing temperature of 300 °C the small uniform crystallites merged and formed small nanocrystalline clusters, while at annealing temperatures higher than 300 °C they grouped together as large clusters. An AFM of unannealed NC-FeSi2 films showed a very smooth surface with a root mean square roughness of 0.81 nm which increased by annealing. Unannealed NC-FeSi2 film surface exhibited an average contact angle of 100.1°, which was hydrophobic. At an annealing temperature of 300 °C, the film surface exhibited the highest contact angle of 106.2°. Average contact angles decreased at annealing temperatures higher than 300 °C.

Study of Annealing Influence on Basic Properties of Indium Tin Oxide Nanorod Films Deposited Using Glancing Angle Ion-Assisted Electron Beam Evaporation.

Indium tin oxide (ITO) nanorod films were deposited onto glass slides and Si wafers using ionassisted electron beam evaporation with a glancing angle deposition technique. The annealing influence on the basic properties of the as-deposited ITO nanorod films was studied in the range of 100-500 °C for two hours in air. The crystallinity of the ITO nanorod films was enhanced with the increasing annealing temperature, and the average transmission of the as-deposited ITO nanorod films in the visible range was 90%. This value did not change significantly after the annealing process. The optical bandgap of the as-deposited ITO nanorod films was 3.94 eV and increased slightly after annealing. The sheet resistance of the as-deposited ITO nanorod films was 12.9 Ω/ and increased to 57.8 Ω/ at an annealing temperature of 500 °C. The as-deposited ITO nanorod films showed nanorod structures with average diameters of 79 nm, which changed slightly with the annealing temperature. The root mean square roughness of the as-deposited ITO nanorod films was 7.9 nm and changed slightly with annealing. The as-deposited ITO nanorod films had an average contact angle of 110.9°, which decreased to 64.2° at an annealing temperature of 500 °C. The experimental results showed that varying the annealing temperature influenced the structural, electrical and wettability properties of the ITO nanorod films while the optical properties and surface morphology were almost unaffected.