A study on characteristic indexesof railway ballast bed underhigh-frequency radar

Purpose–In this paper,a high-frequency radar test system was used to collect the data of clean ballast bed and fouled ballast bed of ballasted tracks,respectively,for a quantitative evaluation of the condition of railway ballast bed.Design/methodology/approach–Based on original radar signals,the time–frequency characteristics of radar signals were analyzed,five ballast bed condition characteristic indexes were proposed,including the frequency domain integral area,scanning area,number of intersections with the time axis,number of timedomain inflection points and amplitude envelope obtained by Hilbert transform,and the effectiveness and sensitivity of the indexes were analyzed.Findings–The thickness of ballast bed tested at the sleep bottom by high-frequency radar is up to 55 cm,which meets the requirements of ballast bed detection.Compared with clean ballast bed,the values of the five indexes of fouled ballast bed are larger,and the five indexes could effectively show the condition of the ballast bed.The computational efficiency of amplitude envelope obtained by Hilbert transform is 140 s$km
1,and the computational efficiency of other indexes is 5 s$km
1.The amplitude envelopes obtained by Hilbert transform in the subgrade sections and tunnel sections are the most sensitive,followed by scanning area.The number of intersections with the time axis in the bridge sections was the most sensitive,followed by the scanning area.The scanning area can adapt to different substructures such as subgrade,bridges and tunnels,with high comprehensive sensitivity.Originality/value–The research can provide appropriate characteristic indexes from the high-frequency radar original signal to quantitatively evaluate ballast bed condition under different substructures.

The calcium uniporter regulates the permeability transition pore in isolated cortical mitochondria

To investigate the influence of the mitochondrial calcium uniporter on the mitochondrial permeability transition pore, the present study observed mitochondrial morphology in cortical neurons isolated from adult rats using transmission electron microscopy, and confirmed the morphology and activity of isolated mitochondria by detecting succinic dehydrogenase and monoamine oxidase, two mitochondrial enzymes. Isolated mitochondria were treated with either ruthenium red, an inhibitor of the uniporter, spermine, an activator of the uniporter, or in combination with cyclosporin A, an inhibitor of the mitochondrial permeability transition pore. Results showed that ruthenium red inhibited CaCl2-induced mitochondrial permeability transition pore opening, spermine enhanced opening, and cyclosporin A attenuated the effects of spermine. Results demonstrated that the mitochondrial calcium uniporter plays a role in regulating the mitochondrial permeability transition pore in mitochondria isolated from the rat brain cortex.

Effect of nicorandil on infarct volume and marker enzyme activity in mitochondria of rats with cerebral ischemia/reperfusion injury

BACKGROUND： Recent studies have suggested that mitochondrial ATP-sensitive K＋ channel openers could reduce myocardium infarct size, and protect the function of the mitochondria. OBJECTIVE： To investigate the changes of cerebral infarction volume and the activity of marker enzymes in brain mitochondria of rats given the ATP-sensitive K＋ channel opener, nicorandil, before focal cerebral ischemia/reperfusion （I/R）. DESIGN, TIME AND SETTING： Randomized, controlled animal experiment, completed at the Brain Scientific Research Center of the Affiliated Hospital of Qingdao University from July to November 2007. MATERIALS： Sixty healthy male Wistar rats weighing 280-300 g. Nicorandil, 5-hydroxydecanoate （5-HD） and cytochrome C were purchased from Sigma in the USA. Standard malondialdehyde （MDA） and protein were purchased from Nanjing Jiancheng Biotechnology Institute. METHODS： Sixty rats were randomly divided into a sham operation group, a middle cerebral artery occlusion （MCAO） group, a nicorandil group and a nicorandil＋5-HD group. MCAO for 2 hours was performed in the MCAO group, nicorandil group and nicorandil＋5-HD group. A total of 5 mL saline were given to the MCAO group before MCAO. The nicorandil group was injected with the ATP-sensitive K＋ channel opener nicorandil 10 mg/kg intraperitoneally 30 minutes before MCAO. The nicorandil＋5-HD group was injected with 5-HD 10 mg/kg intravenously 15 minutes before the same treatment as the nicorandil group. MAIN OUTCOME MEASURES： Infarct volume by total brain slice calculation, activities of succinate dehydrogenase （SDH） and cytochrome oxidase （CO）, and content of MDA were observed at 22 hours of reperfusion after 2 hours MCAO. RESULTS： Sixty rats were included in the final analysis, without any loss. （1） Infarct volume： compared with the MCAO group and nicorandil＋5-HD group, the percentage of infarct volume was significantly decreased in the nicorandil group （P 〈 0.01）. （2） The content of MDA, expression of SDH and CO in brain： the expressions of SDH and CO in the sham operation group were significantly lower than those in the MCAO, nicorandil and nicorandil＋5-HD groups （P 〈 0.01）. The expressions of SDH and CO in the nicorandil group were significantly higher than those in the MCAO and nicorandil＋5-HD groups （P 〈 0.05）. The content of MDA in the brain of the nicorandil group was significantly lower than those in the MCAO and nicorandil＋5-HD groups （P 〈 0.01）. CONCLUSION： Nicorandil can significantly reduce the infarct volume in a rat MCAO model, increase the activity of the mitochondria and protect against cerebral I/R injury.

Mapping of QTLs Associated with Salt Tolerance of Maize Inbred Line at Seedling Stage

[ Objective] This study aimed to map quantitative tarit loci （QTLs） associated with salt tolerance of maize inbred line at seedling stage. [ Method! The recombinant inbred line （RIL） F7 including 171 plants were developed by single seed descent procedure from a combination, Huangzazsi × Mo17, and used to map QTLs associated with salt tolerance, based on the constructed genetic map of SSR markers. [ Resultl A linkage map consisting of 81 SSR markers loci from 10 chromosomes （ 1 428.3 cM in total length, with an average distance of 17.63 cM between two neighbouring loci） was constructed. Six QTI~ associated significantly with salt tolerance were detected at chromosomes 1,5 and 6. [ Conclusion] This study is extremely significant for better understanding sah tolerance-related genes, the genes＇ location and cloning, salt tolerance mechanism and the marker-assisted selection of salt tolerant maize.

Discovery and Preliminary Analysis of a Natural Lateflowering Rice Mutant

In previous experiments, a natural late-flowering mutant was obtained from a late-season japonica rice line. The mutant exhibits no significant differences in various traits except growth period at the basic vegetative growth stage compared with other wild-type varieties. In Jiaxing City, the heading stage of the late-flow- ering mutant was averagely delayed by about 20 days compared with other wild-type varieties. According to the results of progeny investigation and statistical analysis, the late-flowering mutant is controlled by a single recessive gene, which can be utilized with breeding technology to obtain sterile lines and multiple lines, thus expanding the germplasm resources for production application, which laid the foundation for subsequent studies.

Recent progress in terahertz modulation using photonic structures based on two-dimensional materials

Terahertz(THz)technology has attracted great attention in the past few decades for its unique applications in various fields,including spectroscopy,noninvasive detection,wireless communications,and imaging.In parallel to this,the practical,fast,and broadband modulation of THz waves is becoming indispensable.Two-dimensional(2D)materials exhibit unusual optical and electrical properties,which has prompted tremendous interest and significant advances in THz modulation.This review provides the recent progress in 2D materials-based THz modulators,outlining the operating principles,including all-optical,electro-optic,magneto-optic,and other exotic mechanisms.We focus on the recent advances in THz modulation by the designed photonic structures,such as heterostructure,metamaterial,capacitor,optical cavity,and waveguide integration.Lastly,we discussed the challenges and opportunities for 2D materials-based THz modulators and presented our prospects for the future development.