Photoelectron-Regulated Redox Reaction of Polyaniline for Visual Detection of Trace Copper / 分析化学

A photochromic sensing platform composing of emeraldine salt of polyaniline ( ES-PANI ) and titanium dioxide nanoparticles ( TiO2 NPs) for visual detection of trace copper was developed. Under ultraviolet light irradiation, the greenish ES-PANI could be oxidized to dark blue pernigraniline salt by the photogenerated hole of excited TiO2 NPs. In the presence of Cu2+, a light yellow leucoemeraldine salt was visually observed. The overall mechanism of color change was verified to be corresponding to the different redox states of PANI regulated by Cu species during the photochromic process. By integrating the advantages of both photoelectric property and visual detection, the redox reaction-based sensing mechanism led to a good sensitivity and high selectivity in the detection of Cu2+ with the detection limit of 0. 4 μmol/L. Besides the naked eye, two color recognition methods including reading mean green intensities in Photoshop and recording ultraviolet absorbance in microplate reader were also studied. This method was successfully applied to Cu2+ detection in human hair with satisfactory recoveries. More significantly, this sensing platform was really simple, low-cost and able to detect an array of analytes within several minutes without requiring sophisticated equipment. This photoelectron-regulated colorimetric strategy provided a novel concept for the design of visual sensing platform, and could develop the portable test kits for rapid detection in clinical diagnosis.

Measurement of the photoeffect cross section and the K-absorption edge energy of Dy, Ta, Pt and Au atoms using Bremsstrahlung / Medición de la sección eficaz de fotoefecto y de la energía del borde de absorción K de los átomos Dy, Ta, Pt y Au utilizando radiación de frenado

An experimental setup to determine the K-shell photoelectric cross-section of Dy, Ta, Pt and Au atoms was implemented at the Nuclear Analytical Laboratory (LAN) of the InSTEC. Bremsstrahlung photons, produced by - beta particles hitting a thin Ni converter, were used to irradiate the target under study. A HPGe detector, coupled to standard nuclear instrumentation, collected the incident and transmitted spectra. A sharp decrease in intensity at the K-shell binding energy was observed in the transmitted spectra. The photon beam divergence effects were corrected with a calibration curve calculated with Monte Carlo simulations (MCNPX 2.6). In order to establish accurately the cross section at the K-edge energy, the obtained data was processed by two methods: fitting the total cross section to a sigmoidal function, as well as the cross section branches around the K-edge to the empirical law . The Empirical Law method was introduced in this work to minimize the detector resolution effects. The results were compared with experimental and theoretical values showing the best agreement when the thinner targets were used. For the first time the photoeffect cross section at the K-edge energy for Pt is reported at first time.

Se determina la sección eficaz fotoeléctrica de la capa K de los átomos Dy, Ta, Pt y Au en un arreglo experimental desarrollado en el Laboratorio Analítico Nuclear del InSTEC. Los blancos bajo estudio se irradiaron con fotones de frenado producidos en un radiador de Ni por las partículas beta emitidas por una fuente de -. Los espectros incidentes y de transmisión se colectaron en un detector de germanio hiperpuro, acoplado a su instrumentación nuclear estándar. En los espectros de transmisión se observó un decrecimiento agudo de la intensidad correspondiente a la energía del borde K. Los efectos de interacciones múltiples del haz fotónico en las láminas blanco se corrigieron a través de una curva de calibración calculada mediante simulaciones Monte Carlo (MCNPX 2.6). Con vistas a garantizar la mejor precisión en la determinación de la sección eficaz para la energía del borde K, los datos obtenidos se ajustaron según dos comportamientos funcionales en esta región: una sigmoide y una ley empírica del tipo . Este último método se introdujo en el trabajo y permite minimizar los efectos resolutivos. Los resultados obtenidos se compararon con valores teóricos y experimentales, mostrando mayor concordancia cuando se emplean blancos finos. Se reporta, por primera vez, la sección eficaz de fotoefecto en el borde K del platino (Pt).

Discussion of Dual-Energy Imaging with the Dual-source Computer Tomography / 医疗卫生装备

Objective To investigate the principle and its clinical initial application of the dual-energy imaging with the dual-source CT and increase the realization of it. Methods According to the research results of the dual-energy imaging with the dual-source CT and the course of development of the dual-energy imaging to analyze and summarize the basis radiological physics, the principles, the correlation parameters and the clinical initial application of the dual -energy imaging with the dual -source CT. Results The dual -energy imaging with the dual -source CT is different from other common dual-energy imaging, it has its own special feature. Conclusion According to the analysis of the dual-energy imaging with the dual-source CT, greatly increase the realization of the dual-energy imaging with the dual-source CT.