The safety of tooth bleaching, which is based upon hydrogen peroxide (HP) as the active agent, has been questioned. Our aim was to investigate effects 30% HP on human enamel. specimens were divided randomly into three groups and treated with distilled water, HCl, HP, respectively. Raman scattering laser-induced fluorescence enamel determined before after treatment. Microhardness testing scanning electron microscopy also used. results showed that relative intensity changed significantly HCl...

This study presents observations of nighttime spread F/ionospheric irregularities and Es at low middle latitudes in the South East Asia longitude China sectors during recovery phase 7–9 September 2017 geomagnetic storm. In this study, multiple observations, including a chain three ionosondes located about 100°E, Swarm satellites, Global Navigation Satellite System (GNSS) ROTI maps, were used to development process evolution characteristics latitudes. Interestingly, F intense simultaneously...

[1] As an effective means to actively modify the ionosphere, chemical releases can produce artificial ionospheric holes as a consequence of ionization reduction, which have great impact on radio wave propagation. To investigate morphology control by various and resultant effects propagation, quantitative numerical model is developed basis approximate solutions diffusion equation single-point release in uniform atmosphere. While produces ellipsoidal holes, multipoint other types (such...

In this paper, complete complementary code (CCC) sequences are applied to a High Frequency (HF) ionospheric sounding network. Ionosondes distributed at multiple locations use the mutually orthogonal CCC conduct vertical soundings synchronously. At same time, thanks omnidirectional antennas, every station can receive oblique echoes transmitted from others. Due orthogonality between sequences, both and ionograms be simultaneously obtained completely separated. Through method, efficiency...

Observations from the high‐frequency multistatic backscatter sounding radars on a geomagnetically quiet day (minimum D st = −14 nT) captured anti‐equatorward propagation of daytime large‐scale traveling ionospheric disturbance (LSTID) at low‐latitude regions. The observed LSTID was characterized approximately by meridional speed 347 ± 78 m/s and azimuthal angle −4.7 27.6° (counterclockwise north), with period 76 min wavelength 1583 354 km means maximum entropy cross‐spectral analysis....

In this paper, a new dedicated multi-channel ionospheric oblique backscatter sounder is described. A miniaturized L-shaped antenna array was employed for the receiving of echoes in present system. Firstly, two typical adaptive beamforming algorithms were introduced to improve anti-jamming ability. Then, simulations carried out verify performance azimuth and elevation simultaneously. Furthermore, experimental results by sounding system used test beamformers. Results show that radio frequency...

This paper describes a novel sounding system for which the functions of medium frequency (MF) radar and ionosonde are integrated on same hardware platform antenna structure, namely middle atmosphere-ionosphere (MAI) system. Unlike common MF radar, MAI adopts pseudo-random (PRN) phase-coded modulation technology, breaks limitation traditional monopulse mode. Through pulse compression, only small peak power is needed to achieve signal-to-noise ratio (SNR) requirement. The excellent...

A novel land-based high-frequency (HF) geolocation system is proposed. The geolocating signals are transmitted from the stations with known geographic coordinates. Because of ionospheric refraction, propagate as skywave in over-the-horizon (OTH) manner. Therefore, a wide spatial coverage can be achieved. receiving station uses small 2-D antenna array to estimate angle arrival (AOA) each transmitter's signal. An intersecting algorithm based on geometric relations between transmitters, and...

Abstract In this study, an unusual daytime range spread F event recorded by the ionosonde installed at Zhangye (ZHY, 39.4°N, 100.13°E, dip latitude 29.65°N) station during afternoon of December 23, 2016 was presented. Daytime hours have seldom been reported midlatitude regions. addition, observations are mostly frequency F. case, and Es in region were simultaneously observed (15:15‐16:00 LT). Moreover, some distorted traces main occurred on ionograms morning. The result these seems to...

66 samples from the human oral mucosa tissue, including 43 normal and 23 malignant tissue were measured by confocal Raman microspectroscopy. The low signal-to-background ratio spectra tissues obtained this technique without any sample preparation. A preprocessed algorithm based on wavelet analysis was used to reduce noise eliminate background of spectra. Then principal components (PCA) as a classification method in order identify whether is or not. integrated areas four normalized wavenumber...

Ground-based oblique incidence sounding (OIS) is an important means to investigate the ionosphere. As OIS ionogram a visual representation of parameters, such as group distance and maximum usable frequency (MUF), it great significance for improving quality range resolution. This will facilitate automatic interpretation inversion ionograms obtain fine structure spatial–temporal evolutions In this paper, novel signal processing scheme proposed based on Eigenspace-based (ESB) beamforming...

Abstract The generation and evolution of artificial plasma clouds is a complicated process that strongly dependent on the background environment release conditions. In this paper, based three-dimensional two-species fluid model, characteristics under various conditions were analyzed numerically. particular, effect ionospheric density gradient ambient horizontal wind field was taken into account in our simulation. results show an asymmetric cloud structure occurs vertical direction when...

Abstract This paper describes a method for automatically scaling HF swept‐frequency backscatter ionograms, which can be applied to low‐power oblique sounding system. Based on the information of vertical echo in ionogram, propagation mode is recognized from amplitude differences between E layer and F echoes. Points leading edge are extracted by using minimum group path delay theory. The spurious points removed residual analysis. A multiple linear polynomial was adopted fit points. Smooth...

This paper introduces a new type Multi-Function Ionospheric Sounding System (MFISS), which bases on the PXI bus. The capabilities of ionospheric vertical sounding, oblique sounding and backscattering were integrated in single MFISS, it overcomes disadvantages original equipments have feature with less function, limited coverage, obtaining parameters, also can achieve function acquiring omnibearing geophysical characteristics, ionosphere channel propagation characteristics radio environment...

The basic configuration of the Wuhan MST (Mesosphere-Stratosphere-Troposphere) radar, which is currently designed and constructed by School Electronic Information, University, preliminarily described in this paper. radar operates at VHF band preoccupied with real-time characteristics turbulence wind field vector height range 1-100km a high temporal spatial resolution. extensive feature points to feasibility low thermosphere if desired. This all solid state, coherent pulse Doppler China's...