9 research outputs found
Research and experimental verification on low-frequency long-range underwater sound propagation dispersion characteristics under dual-channel sound speed profiles in the Chukchi Plateau
The dual-channel sound speed profiles of the Chukchi Plateau and the Canadian
Basin have become current research hotspots due to their excellent
low-frequency sound signal propagation ability. Previous research has mainly
focused on using sound propagation theory to explain the changes in sound
signal energy. This article is mainly based on the theory of normal modes to
study the fine structure of low-frequency wide-band sound propagation
dispersion under dual-channel sound speed profiles. In this paper, the problem
of the intersection of normal mode dispersion curves caused by the dual-channel
sound speed profile (SSP) has been explained, the blocking effect of seabed
terrain changes on dispersion structures has been analyzed, and the normal
modes has been separated by using modified warping operator. The above research
results have been verified through a long-range seismic exploration experiment
at the Chukchi Plateau. At the same time, based on the acoustic signal
characteristics in this environment, two methods for estimating the distance of
sound sources have been proposed, and the experiment data at sea has also
verified these two methods.Comment: 30 pages, 18 figure
Research and experimental verification on low-frequency long-range sound propagation characteristics under ice-covered and range-dependent marine environment in the Arctic
At present, research on sound propagation under the Arctic ice mainly focuses
on modeling and experimental verification of sound propagation under sea ice
cover and unique sound velocity profiles. Among them, the main research object
of concern is sound transmission loss, and this article will delve into the
time-domain waveform and fine dispersion structure of low-frequency broadband
acoustic signals. Firstly, based on the theory of normal modes, this article
derives the horizontal wavenumber expression and warping transformation
operator for refractive normal modes in the Arctic deep-sea environment.
Subsequently, based on measured ocean environmental parameters and sound field
simulation calculations, this article studied the general laws of low-frequency
long-range sound propagation signals in the Arctic deep-sea environment, and
elucidated the impact mechanism of environmental factors such as seabed terrain
changes, horizontal changes in sound velocity profiles (SSPs), and sea ice
cover on low-frequency long-range sound propagation in the Arctic. This article
validates the above research viewpoint through a sound propagation experiment
conducted in the Arctic with a propagation distance exceeding 1000km. The
marine environment of this experiment has obvious horizontal variation
characteristics. At the same time, this article takes the lead in utilizing the
warping transformation of refractive normal waves in the Arctic waters to
achieve single hydrophone based separation of normal waves and extraction of
dispersion structures, which is conducive to future research on underwater
sound source localization and environmental parameter inversion based on
dispersion structures.Comment: 46 pages, 35 figure
Assay for the developmental toxicity of safflower (Carthamus tinctorius L.) to zebrafish embryos/larvae
Objective: To explore the developmental toxicity and the potential toxicological mechanism of safflower (Carthamus tinctorius L.) on zebrafish embryos/larvae.
Methods: Mortality, malformations and increased apoptosis induced by safflower were assessed in zebrafish embryos from 6 to 96 hours post-fertilization. Enzymes and genes in the anti-oxidative and apoptotic pathways were also assayed.
Results: The lethal concentration 50 of safflower to zebrafish embryos was 345.6 mg/L. Hatching inhibition, abnormal spontaneous movement, depressed heart rate, pericardial edema, yolk sac edema, abnormal head-trunk angle, inhibition of melanin release, enlarged yolk, and short body length were observed in safflower-treated zebrafish. Additional apoptotic cells mainly appeared around the heart. Safflower exposure changed the activities of defense enzymes (SOD↑, CAT↑, MDA↑, GPX without trend), increased MDA content, decreased caspase-3 activity, and altered mRNA levels of related genes (ogg1↓, p53↓, Cu/Zn-sod↑, Mn-sod↓, cat↓, gpx↑).
Conclusion: Safflower exhibits developmental toxicity for zebrafish embryos/larvae. The developing heart was speculated as the target organ of toxicity. Oxidative stress and increased apoptosis have roles in the developmental toxicity of safflower. This article provides a novel method to research the teratogenicity and possible mechanisms of toxicity of traditional Chinese medicines that are prohibited or contraindicated in pregnant women
Exploring the Effect Mechanism of Alkyl Chain Lengths on the Tribological Performance of Ionic Liquids
In this work, four
kinds of imidazole phosphate ionic liquids (ILs)
with different anionic and cationic alkyl chain lengths were synthesized.
The physicochemical properties and tribological performance of ILs
were evaluated. The experimental results revealed that the tribological
properties of ILs were positively correlated with the cationic chain
length and negatively correlated with the anionic chain length. The
effect mechanism can be summarized in two aspects: on the one hand,
anions with shorter alkyl chain lengths possess stronger adsorption
performance and better film forming ability on the friction pair surfaces,
which makes the ILs form more robust and stable lubricating film;
on the other hand, ILs with longer cationic alkyl chain lengths possess
milder tribo-chemical reactions, which can effectively enhance the
tribological performance and decrease the corrosion wear