Single-atom nanocatalysts for biosensing application

Single-atom (SA) catalysts, as a rising star in catalytic field, have many advantages over traditional nanocatalysts. The enhanced catalytic activity, variable and simple structure as well as clear active sites of SA catalysts advance the innovation of biosensing techniques. In this review, we will provide the latest research progress of SA catalysts in biosensing field, and systematically summarize their sensing applications, especially emphasing on the biosensing strategies on the determination of disease-related biological matrices (H2O2, biological enzyme, NO, etc) and environmental pollutants (organophosphorus pesticides, heavy metal ions and volatile organic compounds). Finally, we will provide the challenges that SA catalysts still faced.

Miniaturized Dual-Band Bandpass Filter Using T-Shaped Line Based on Stepped Impedance Resonator with Meander Line and Folded Structure

A stepped impedance resonator (SIR) is suitable for designing a dual-band bandpass filter (BPF) that can be adjusted to reject spurious bands. A BPF is proposed using an SIR T-shaped meander line and folded structure. The BPF mainly comprises a meander line, a folded structure, and a T-shaped line. A novel BPF is used for the T-shaped line, which operates as a band-stop filter connecting to the center of the BPF. As a result, the complete BPF enables dual-band operation. The insertion and return losses of the first frequency passband (f01) are 0.024 and 17.3 dB, respectively, with a bandwidth of 46% at a center frequency of 2.801 GHz (2.2–3.48 GHz). The insertion and return losses of the second frequency passband (f02) are 0.026 and 17.2 dB, respectively, with a bandwidth of 10% at a center frequency of 4.351 GHz (4.13–4.55 GHz). The proposed BPF provides low loss, a simple structure, and a small size of only 4.29 × 4.08 mm, and it can be integrated into mobile communications systems.

HiTOP Is Not an Improvement Over the DSM

In their response to our article (both in this issue), DeYoung and colleagues did not sufficiently address three fundamental flaws with the Hierarchical Taxonomy of Psychopathology (HiTOP). First, HiTOP was created using a simple-structure factor-analytic approach, which does not adequately represent the dimensional space of the symptoms of psychopathology. Consequently, HiTOP is not the empirical structure of psychopathology. Second, factor analysis and dimensional ratings do not fix the problems inherent to descriptive (folk) classification; self-reported symptoms are still the basis on which clinical judgments about people are made. Finally, HiTOP is not ready to use in real-world clinical settings. There is currently no empirical evidence demonstrating that clinicians who use HiTOP have better clinical outcomes than those who use the Diagnostic and Statistical Manual of Mental Disorders ( DSM). In sum, HiTOP is a factor-analytic variation of the DSM that does not get the field closer to a more valid and useful taxonomy.

Switchable acoustic metagrating for three-channel retroreflection and carpet cloaking

In this paper, we propose a switchable acoustic metagrating composed of periodic grooves for realizing switchable functionalities of three-channel retroreflection and carpet cloaking. The groove parameters are determined by calculating and analyzing the reflectance of different diffracted waves, and only one propagating reflected wave is allowed. Theoretical analysis and numerical simulations are performed to validate the three-channel retroreflection and carpet cloaking performances of the proposed metagrating. Our research work provides a practical and simple method to design acoustic devices with switchable functionalities and simple structure, and has potential applications in practical fields of acoustic sensing and acoustic communication.

A Dual/Single Wideband Switchable Metamaterial Absorber at Low Frequency

Based on PIN diode and resistive film, a dual/single wideband switchable metamaterial absorber at low frequency is presented in this paper. Its absorption is over 90% from 0.8GHz to 1.5GHz and from 4.2GHz to 5.2GHz while the PIN diode operates in forward biased condition. On the contrary, with the PIN diode acting in reverse biased condition, the above 90% absorption occurs from 1.1GHz to 3.2GHz. The surface current distributions at the absorption frequencies are monitored to explain the reason of wideband absorption. The simulation results show that the absorption property of the metamaterial absorber is polarization-sensitive. The metamaterial absorber possesses the advantages of simple structure, wideband, dual/single band, and switchable performance.

A dual responsive fluorescent probe for selective detection of cysteine and bisulfite and its application in bioimaging

A coumarin-based dual responsive fluorescent probe with a simple structure was developed for the detection of Cys and HSO3−.

Simple structure descriptors quantifying the diffusion of ethene in small-pore zeolites: Insights from molecular dynamic simulations

Small-pore zeolites with 8-rings are pivotal catalytic materials to produce light olefins from non-petroleum resources employing methanol-to-olefins or syngas-to-olefins processes. The constraints of cage openings on the diffusion of light...

Encoding Conversion Algorithm of Quaternary Triangular Mesh

In the process of global information construction, different fields have built their own discrete global grid systems (DGGS). With the development of big data technology, data exchange, integration, and update have gradually become a trend, as well as the associative integration of different DGGS. Due to the heterogeneity of DGGS and the different encoding rules, how to build the encoding conversion rules and data mapping relationship between the same object in various DGGS is an effective support and key technology to achieve the interoperability of DGGS. As a kind of multipurpose DGGS, the quaternary triangular mesh (QTM) has become an effective spatial framework for constructing the digital earth because of its simple structure. At present, there are many schemes for QTM encoding research, which plays a key role in the development of QTM, but at the same time, it also leads to difficulties in the communication and integration of QTM under different encoding. In order to solve this problem, we explore the characteristics of QTM encoding, and put forward three conversion algorithms: resampling conversion algorithm, hierarchical conversion algorithm, and row–column conversion algorithm.

Adaptive Fuzzy Neural Network PID Algorithm for BLDCM Speed Control System

Because of its simple structure, high efficiency, low noise, and high reliability, the brushless direct current motor (BLDCM) has an irreplaceable role compared with other types of motors in many aspects. The traditional proportional integral derivative (PID) control algorithm has been widely used in practical engineering because of its simple structure and convenient adjustment, but it has many shortcomings in control accuracy and other aspects. Therefore, in this paper, a fuzzy single neuron neural network (FSNNN) PID algorithm based on an automatic speed regulator (ASR) is designed and applied to a BLDCM control system. This paper introduces a BLDCM mathematical model and its control system and designs an FSNNN PID algorithm that takes speed deviation e at different sampling times as inputs of a neural network to adjust the PID parameters, and then it uses a fuzzy system to adjust gain K of the neural network. In addition, the frequency domain stability of a double closed loop PID control system is analyzed, and the control effect of traditional PID, fuzzy PID, and FSNNN PID algorithms are compared by setting different reference speeds, as well as the change rules of three-phase current, back electromotive force (EMF), electromagnetic torque, and rotor angle position. Finally, results show that a motor controlled by the FSNNN PID algorithm has certain superiority compared with traditional PID and fuzzy PID algorithms and also has better control effects.

An orbital angular momentum acoustic metasurface for underwater defect detection

Fourier diffraction theorem can rapidly predict scattering characteristics of scatterers. This paper theoretically proposes Orbital Angular Momentum (OAM) to simplify the reference library in the underwater Fourier diffraction theorem. An acoustic metasurface is designed to replace the traditional phased array, meanwhile the underwater defect detection combining OAM and Fourier diffraction theorem is verified in the simulation. This acoustic metasurface has a high signal-to-noise ratio (SNR) when used for underwater defect detection. Compared with the traditional underwater defect detection method, the underwater defect detection method proposed in this paper has the advantages of simple structure and no reference pattern library.