Department of Chemistry, University of Pavia, Via Taramelli n.12, 27100 Pavia, Italy.
Published: August 2022
AI Article Synopsis
Article Abstract
An optical sensor for uranyl has been prepared based on a gold-plated D-shaped plastic optical fiber (POF) combined with a receptor consisting of a bifunctional synthetic molecule, 11-mercaptoundecylphosphonic acid (MUPA), with a phosphonic group for complexing the considered ion, and a sulfide moiety through which the molecule is fixed at the gold resonant surface as a molecular layer in an easy and reproducible way. The sensor is characterized by evaluating the response in function of the uranyl concentration in aqueous solutions of different compositions and real-life samples, such as tap water and seawater. The mechanism of the uranyl/MUPA interaction was investigated. Two different kinds of interactions of uranyl with the MUPA layer on gold from water are observed: a strong one and a weak one. In the presence of competing metal ions as Ca and Mg, only the strong interaction takes place, with a high affinity constant (around 10 M), while a somewhat lower constant (i.e., around 10 M) is obtained in the presence of Mg which forms stronger complexes with MUPA than Ca. Due to the high affinity and the good selectivity of the recognition element MUPA, a detection limit of a few μg L is reached directly in natural water samples without any time-consuming sample pretreatment, making it possible for rapid, in situ controls of uranyl by the proposed sensor.
College of Information Science and Engineering, Northeastern University, Shenyang, 110819, China; Hebei Key Laboratory of Micro-Nano Precision Optical Sensing and Measurement Technology, Qinhuangdao, 066004, China.
A novel dual-parameter optical fiber biosensor based on surface plasmon resonance (SPR) for simultaneous measurement of urea and uric acid concentrations is proposed in this paper. Based on the principle of positive and negative electric combination, ZnO nanoparticles is selected as the matrix for immobilizing urease and uricase with selective recognition ability, which can also be used as a sensitizing material to increase the refractive index detection sensitivity of SPR by 22%. Then, Nafion ion exchange membrane was introduced to wrap the urea sensing area to avoid crosstalk caused by the overlap of adjacent sensing areas.
Harvard Medical School, Boston, MA 02114, USA; Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Cardiology, Erasmus Medical Center, Rotterdam GD3015, The Netherlands; Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.
Photoacoustic microscopy (PAM) is a high-resolution and non-invasive imaging modality that provides optical absorption contrast. By employing dual- or multiple-wavelength excitation, PAM extends its capabilities to offer valuable spectroscopic information. To achieve efficient multispectral PAM imaging, an essential requirement is a light source characterized by a high repetition rate and switching rate, a ≈microjoule pulse energy, and a ≈nanosecond pulse duration.
Optical sensors are among the most significant optical devices that have found extensive applications for THz sensing. Surface plasmon-based sensors have attracted increasing attention more than other kinds of optical sensors such as photonic crystal, optical fiber, and graphene sensors, owing to their compact footprint, fast reaction, and high sensitivity value. Therefore, this work reviews plasmonic sensor structures divided into three general categories.
Background: Bipolar disorder (BD) is a psychiatric condition with significant health implications due to its comorbidities, premature mortality, and functional impairments. Despite extensive research on treatment and rehabilitation, gaps remain in diagnosis and monitoring. Therefore, there is a need for biomarkers to identify individuals at risk for disease progression or excacerbation.
Commonly used linear equalizers in optical transmissions may induce in-band noise enhancement in the high-frequency region, degrading signaling performance. In this Letter, we propose for the first, to our knowledge, time, to mitigate the multi-input-multi-output (MIMO) equalizer-enhanced noise (EEN) in coupled-core multicore fiber (CC-MCF) systems by utilizing the spectral shaping (SS) filter and maximum likelihood sequence detection (MLSD), which have shown effective EEN mitigation in SMF systems. However, CC-MCF systems feature multiple spatial channels, each requiring separate coefficient optimization for SS filters corresponding to each output of MIMO.
