Designing of CuS growing on Bi2WO6 nanosheet heterostructures based on a photoelectrochemical aptasensor for detecting ofloxacin.

Bi2WO6 (BW) was compounded with different contents of copper sulfide (CuS) by a two-step procedure. The chemical composition and morphology of the materials were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The results of photoelectrochemical (PEC) tests showed that CuS can improve the PEC performance of semiconductor materials and it has the best performance when the CuS mass fraction is 5%. Therefore, CuS/BW-5% nanocomposite has been constructed as ofloxacin (OFL) drug PEC aptasensors by binding of aptamer receptors. The PEC aptasensor based on CuS/BW-5% has a linear relationship for OFL of 1-12,000 nM and a determination limit of 0.35 nM. Since the photoelectron potential generated by CuS/BW-5% heterojunction reduces the combination of photogenerated electrons and holes CuS/BW-5% has a better photoelectrocatalytic performance. Graphical abstract Schematic presentation of a photoelectrochemical aptasensor based on CuS/Bi2WO6 for the determination of OFL.

Control system of neoclassical tearing modes in real time on HL-2A tokamak.

The stability and performance of tokamak plasmas are routinely limited by various magneto-hydrodynamic instabilities, such as neoclassical tearing modes (NTMs). This paper presents a rather simple method to control the NTMs in real time (RT) on a tokamak, including the control principle of a feedback approach for RT suppression and stabilization for the NTMs. The control system combines Mirnov, electron cyclotron emission, and soft X-ray diagnostics used for determining the NTM positions. A methodology for fast detection of 2/1 or 3/2 NTM positions with 129 × 129 grid reconstruction is elucidated. The forty poloidal angles for steering the electron cyclotron resonance heating (ECRH)/electron cyclotron current drive launcher are used to establish the alignment of antenna mirrors with the center of the NTM and to ensure launcher emission intersecting with the rational surface of a magnetic island. Pilot experiments demonstrate the RT control capability to trace the conventional tearing modes (CTMs) in the HL-2A tokamak. The 2/1 CTMs have been suppressed or stabilized by the ECRH power deposition on site or with the steerable launcher.