Fourier Motion Processing in the Optic Tectum and Pretectum of the Zebrafish Larva

In the presence of moving visual stimuli, the majority of animals follow the Fourier motion energy (luminance), independently of other stimulus features (edges, contrast, etc.). While the behavioral response to Fourier motion has been studied in the past, how Fourier motion is represented and processed by sensory brain areas remains elusive. Here, we investigated how visual moving stimuli with or without the first Fourier component (square-wave signal or missing fundamental signal) are represented in the main visual regions of the zebrafish brain. First, we monitored the larva's optokinetic response (OKR) induced by square-wave and missing fundamental signals. Then, we used two-photon microscopy and GCaMP6f zebrafish larvae to monitor neuronal circuit dynamics in the optic tectum and the pretectum. We observed that both the optic tectum and the pretectum circuits responded to the square-wave gratings. However, only the pretectum responded specifically to the direction of the missing-fundamental signal. In addition, a group of neurons in the pretectum responded to the direction of the behavioral output (OKR), independently of the type of stimulus presented. Our results suggest that the optic tectum responds to the different features of the stimulus (e.g., contrast, spatial frequency, direction, etc.), but does not respond to the direction of motion if the motion information is not coherent (e.g., the luminance and the edges and contrast in the missing-fundamental signal). On the other hand, the pretectum mainly responds to the motion of the stimulus based on the Fourier energy.

Indirect Electrochemical Determination of Chlorpropamide Through Its Interaction with Valsartan Using Square Wave Voltammetry

A square wave voltammetric technique coupled with three electrode detection system consist of hanging mercury drop electrode (HMDE) as working electrode, 1mm platinum wire as an auxiliary electrode (Pt-wire) and silver/silver chloride saturated potassium chloride (Ag/AgCl.sat.KCl) as reference electrode was used to determine the chlorpropamide indirectly through its interaction with valsartan, chlorpropamide gives no reduction peaks in the studied range. The effect of pH and the stability of the measurement were examined calibrations curve of chlorpropamide was constructed and the relation between current and concentration of chlorpropamide was linear with R2 value = 0.9944. The limit of detection for chlorpropamide was 4.89 x 10-9 M through its interaction with valsartan.

Analysis of Rotor Position Detection Performance According to the Frequency of Square Waveform Voltage in the Harmonic Injection Sensorless Method through HILS

In this paper, the rotor position estimation performance of the sensorless scheme for permanent magnet synchronous motors (PMSMs) implemented through the injection of high-frequency square-wave voltage according to the frequency of the square-wave voltage is presented through HILS (Hardware In the Loop Simulation) experiments. An inverter using an IGBT device usually has a switching frequency of around 15 kHz. On the other hand, GaN devices that can be switched on and off at frequencies higher than 100 kHz have been recently developed, and research is being actively conducted to apply GaNs to a variable speed system. The purpose of this study is to conduct HILS experiments to analysis the rotor position estimation ability of the sensorless technique in cases where a high switching frequency was applied, such as GaN devices, with that of a system having a usual switching frequency, such as IGBT. In the HILS system used in this study, an inverter and motor model implemented with Simulink are located in a real-time simulator. A sensorless motor control method was implemented with an FPGA control board, which includes a PWM interrupt service routine of 100 kHz frequency and a harmonic injection and position detection algorithm. The HILS experiments show rotor position detection errors according to the various frequency of the harmonic voltage injected for estimating the rotor position with a PWM frequency of 100 kHz cases. According to the experimental results, good position estimation was possible not only when the harmonic of 10 kHz corresponding to 1/10 of the PWM frequency was injected, but also when the harmonic of 1 kHz corresponding to 1/100 of the PWM frequency was injected. The experiments suggest that position estimation errors decrease as the frequency of the harmonic voltage increases, and, based on the foregoing, it is thought that the application of a GaN device capable of realizing a high switching frequency in a variable speed drive system can be another advantage.

Square-Wave Voltammetric Sensing of Lawsone (2- Hydroxy-1,4-Naphthoquinone) Based on the Enhancement Effect of Cationic Surfactant on Anodically Pretreated Boron-Doped Diamond Electrode

In this reported work, an anodically pretreated boron-doped diamond (BDD) electrode was used for the inexpensive, simple and quick detection of a natural dye, lawsone. Lawsone had a well-defined, irreversible and diffusion-controlled oxidation peak at approximately +0.19 V in phosphate buffer solution (PBS, 0.1 M, pH 2.5) using cyclic voltammetry (CV). The oxidation peak heights of lawsone were significantly increased in PBS using the cationic surfactant cetyltrimethylammonium bromide (CTAB). Under optimized experimental conditions, the calibration curve was linear over a concentration range of 0.1–5.0 μM with detection limit of 0.029 μM in 0.1 M PBS (pH 2.5) containing 0.1 mM CTAB by using square-wave voltammetry (SWV). To evaluate the practical applicability of the BDD electrode, it was used for the quantification of lawsone in commercial henna, a natural dye made from the leaves of the henna plant.