Application of extended time-frequency domain average in ultrasonic detecting

Ultrasonic signal detection is essential for the ultrasonic-based applications such as ultrasonic flow measurements and nondestructive testing. The paper proposes three extended time-frequency domain average (ETFDA) techniques, which are based on the smoothed pseudo-Wigner-Ville distribution, continuous wavelet transform and Hilbert-Huang transform. These techniques combine beneficial time-frequency localization characteristics of the time-frequency analysis and abilities of the time domain averaging (TDA) to suppress noise interference. They are thus well adapted for detection of the ultrasonic signals even when they are strongly smeared by the noise or distorted in the medium. A number of tests conducted on simulated and actual ultrasonic signals have demonstrated that ETFDA provides a solid performance

On the performance of superposition window

Superposition window is often used in the digital signal processing and other fields of signal processing such as power spectral estimation and adaptive time-frequency analysis. Different overlap and windows used in superposition system may affect the final results. The main contribution of this paper is in providing the insight into the properties of the overlap-add technique with different window or overlap ratio, which is very helpful in selecting these parameters for a practical application

Application of extended time-frequency domain average in ultrasonic detecting

Ultrasonic signal detection is essential for the ultrasonic-based applications such as ultrasonic flow measurements and nondestructive testing. The paper proposes three extended time-frequency domain average (ETFDA) techniques, which are based on the smoothed pseudo-Wigner-Ville distribution, continuous wavelet transform and Hilbert-Huang transform. These techniques combine beneficial time-frequency localization characteristics of the time-frequency analysis and abilities of the time domain averaging (TDA) to suppress noise interference. They are thus well adapted for detection of the ultrasonic signals even when they are strongly smeared by the noise or distorted in the medium. A number of tests conducted on simulated and actual ultrasonic signals have demonstrated that ETFDA provides a solid performance

Application of extended time-frequency domain average in ultrasonic detecting

Ultrasonic signal detection is essential for the ultrasonic-based applications such as ultrasonic flow measurements and nondestructive testing. The paper proposes three extended time-frequency domain average (ETFDA) techniques, which are based on the smoothed pseudo-Wigner-Ville distribution, continuous wavelet transform and Hilbert-Huang transform. These techniques combine beneficial time-frequency localization characteristics of the time-frequency analysis and abilities of the time domain averaging (TDA) to suppress noise interference. They are thus well adapted for detection of the ultrasonic signals even when they are strongly smeared by the noise or distorted in the medium. A number of tests conducted on simulated and actual ultrasonic signals have demonstrated that ETFDA provides a solid performance

Peptidomics approaches to the discovery and ACE inhibitory effect of casein peptides derived from fermented bovine milk by kefir grains

IntroductionKefir grains with efficient proteolytic system is an excellent starter culture for the production of bioactive peptides and milk products. This study explores the casein peptides derived from fermented bovine milk by kefir grains using the peptidomics approaches. The angiotensin converting enzyme (ACE) inhibitory activity of these peptides were also investigated.MethodsAfter fermentation, peptidomics based on the LC-MS/MS was used to investigate the dynamic profile and the structure specificity of generated peptides. The ACE inhibitory activity of peptides was determined by measuring the amount of hippuric acid (HA) by a spectrophotometer at 228 nm.ResultsThe results indicated that the cell envelope proteinases (CEPs) were the PI-/PIII-type. A total of 122 peptides were identified. The β-casein was preferentially hydrolyzed by kefir grains, and the main hydrolysis regions were f57-93, f132-160 and f192-209. The αs1-, and κ-casein were also hydrolyzed by a weaker degree. In the process of fermentation, the accumulated peptides increased with the fermentation time. The fermentation products exhibited ACE inhibitory activity, and this bioactivity remained 63% after simulated gastrointestinal (GI) digestion in vitro. Additionally, 14 Pro-containing peptides with ACE inhibitory activity were also identified.ConclusionThese results provide new insights and evidence to investigate the bioactive milk peptides generated by kefir grains fermentation, as well as a reference for the development of functional foods

Atomic-layer molybdenum sulfide optical modulator for visible coherent light

Coherent light sources in the visible range are playing important roles in our daily life and modern technology, since about 50% of the capability of the our human brains is devoted to processing visual information. Visible lasers can be achieved by nonlinear optical process of infrared lasers and direct lasing of gain materials, and the latter has advantages in the aspects of compactness, efficiency, simplicity, etc. However, due to lack of visible optical modulators, the directly generated visible lasers with only a gain material are constrained in continuous-wave operation. Here, we demonstrated the fabrication of a visible optical modulator and pulsed visible lasers based on atomic-layer molybdenum sulfide (MoS 2), a ultrathin two-dimensional material with about 9-10 layers. By employing the nonlinear absorption of the modulator, the pulsed orange, red and deep red lasers were directly generated. Besides, the present atomic-layer MoS 2 optical modulator has broadband modulating properties and advantages in the simple preparation process. The present results experimentally verify the theoretical prediction for the low-dimensional optoelectronic modulating devices in the visible wavelength region and may open an attractive avenue for removing a stumbling block for the further development of pulsed visible lasers

Gut microbiota influences feeding behavior via changes in olfactory receptor gene expression in Colorado potato beetles

The Colorado potato beetle (CPB) is an internationally recognized plant quarantine pest that causes serious losses to potato agricultural production. The gut microbiota plays an important role in its growth and development, and the olfactory system plays an important role in insect feeding behavior. The gut microbiota is known to be capable of inducing changes in the olfactory systems of insects. However, the way these associated gut microbes influence the feeding-related behaviors of CPBs remains unclear. To explore the relationship between them, fresh potato leaves immersed in a mixture of five antibiotics (tetracycline, penicillin, ofloxacin, ciprofloxacin, and ampicillin) at specific concentrations for 1 h were fed to adult CPBs to reduce the abundance of gut microbes. We found that the feeding behavior of CPBs was significantly affected by the gut microbiota and that Pseudomonas was significantly higher in abundance in the control group than in the antibiotic group. We then used transcriptome sequencing to explore the differences in olfactory receptor genes in the heads of non-treatment and antibiotic-fed CPBs. Through Illumina Hiseq™ sequencing and screening of differential genes, we found that the olfactory receptor gene LdecOR9 was significantly upregulated and LdecOR17 was significantly downregulated after antibiotic feeding. A real-time polymerase chain reaction was used to verify the changes in olfactory receptor gene expression in the non-treatment groups and antibiotic-treated groups. The feeding behavior was partially rescued after CPBs were re-fed with intestinal bacteria. These results indicate that a certain amount of gut microbiota can result in the loss of the olfactory discrimination ability of CPBs to host plants. In summary, this study investigated the relationship between gut microbiota and olfactory genes, providing a reference for research on microbial control