查看更多>>摘要：? 2022This article proposes a scheme for DC nitrogen-vacancy (NV) center magnetometry that combines the advantages of the lock-in detection and pulse-type schemes. The proposed pulsed lock-in scheme does not lead to optical power broadening of optically-detected magnetic resonance, resulting in smaller linewidth, higher contrast, and better photon shot-noise-limited sensitivity compared with the conventional continuous-wave lock-in scheme. The optimal conditions, optimal sensitivity, and noise-suppression capability of the proposed method are compared with those of the conventional methods from both theoretical and experimental points of view. Through experimental measurements, an improvement by a factor of four in the sensitivity and an improvement by a factor of 60 in the minimum resolvable magnetic field (MRMF) compared with conventional method were obtained. Using a confocal experiment setup, the proposed scheme achieves an MRMF of 100 pT and a sensitivity of 3 nT·Hz-1/2 corresponding to a volume-normalized sensitivity of 2.5 pT/(Hz·mm?3)1/2, demonstrating the potential of this method in magnetic measurement applications with high sensitivity and high spatial resolution.
查看更多>>摘要：? 2022 Elsevier B.V.In the current study, carbon dots/cerium oxide (CDs/CeO2) nanocomposites-modified screen printed carbon electrode, SPCE (CDs/CeO2/SPCE) was developed for the highly sensitive and selective detection of doxorubicin (DOX), an anticancer drug. Here, firstly we have synthesized cerium oxide nanoparticles (CeO2NPs) from ammonium cerium nitrate and urea by simple refluxing, and then CDs were synthesized by using taurine (an essential amino acid) via thermal decomposition method. After that CDs/CeO2 nanocomposites have been synthesized with different wt% of CDs (0.5–5 wt%) via a facile hydrothermal method. The synthesized nanocomposites exhibited higher efficiency towards the electrochemical detection of DOX as compared to bare CeO2NPs and CDs by promoting electron transfer reaction at SPCE surface with increasing amount of CDs. The 5 wt% nanocomposite (CDs-5.0/CeO2) showed the highest oxidation response towards DOX (20 μM) at an optimized pH of 5. The cyclic voltammograms revealed that CDs-5.0/CeO2/SPCE sensing system exhibited a linear response (correlation coefficient, R2 = 0.98) between oxidation peak current and DOX concentration in the range of 0.2–20 μM, with a low detection limit of 0.09 μM. Moreover, the modified CDs-5.0/CeO2/SPCE sensor exhibited superior selectivity towards DOX in the presence of common interferents. This work demonstrated that the novel CDs/CeO2/SPCE sensor can be effectively applied to detect DOX in pharmaceutical samples or in biological fluids.
查看更多>>摘要：? 2022 Elsevier B.V.With the advent of 5G massive data, it is critical to improve the frequency and bandwidth of surface acoustic wave devices. In this work, ZnO, AlN and LiNbO3 piezoelectric materials were applied to a three-layer structure based on diamond as the substrate. Unlike conventional structures, widths of two piezoelectric materials are different. The electromechanical coupling coefficient based on the ZnO/ZnO/diamond structure can be remarkably improved to 8.26%, while a high frequency of 2 GHz can also be obtained. The structure based on the AlN/AlN/diamond structure is more inclined to obtain a high frequency of 3.76 GHz and an electromechanical coupling coefficient of 4.64%. Rational selection of piezoelectric materials and film thickness of surface acoustic wave devices can achieve different degrees of enhancement of electromechanical coupling coefficients and frequency. Finally, it was found that the larger electric potential on the surface of diamond will result in a larger electromechanical coupling coefficient when the first layer of piezoelectric material is identical.
NSTL
Elsevier