Preparation and Characterization of Surface Modified PPTA Fibers by Ultrasonic-Assisted Hydrogen Peroxide Solutions

Zhao Jia,Chunmei Duan 한국섬유공학회 2019 Fibers and polymers Vol.20 No.11

The simplest peroxide, hydrogen peroxide (H2O2) was used to prepare the surface modified poly(p-phenyleneterephthalaramide) (PPTA) fibers under the assistant of ultrasonic vibration. Fourier transform infrared spectroscopy (FTIR)spectra indicated the increase of the active polar groups on the surface of the fibers. X-ray photoelectron spectroscopy (XPS)analysis confirmed that more carboxyl groups and hydroxyl groups have been obtained after this treatment. Scanning electronmicroscope (SEM) showed that the surface roughness of the fibers has been improved accordingly. The interfacial propertiesof modified PPTA fiber/epoxy composites were investigated by the single fiber pull-out test (SFP). The results showed thatthe interfacial shear strength (IFSS) of PPTA/epoxy composites was remarkably improved by 42.14 % while the breakingstrength was not affected appreciably. The modified fiber presented 26.9 % higher moisture regain compared with theoriginal fiber. It proved to be an efficient method to make the surface modified PPTA fiber for the application of the advancedcomposites at a relatively low cost.

POSITIVE SOLUTION FOR SYSTEMS OF NONLINEAR SINGULAR BOUNDARY VALUE PROBLEMS ON TIME SCALES

Chunmei Miao,Dehong Ji,Junfang Zhao,Weigao Ge,Jiani Zhang 한국수학교육학회 2009 純粹 및 應用數學 Vol.16 No.4

In this paper, we deal with the following system of nonlinear singular boundary value problems(BVPs) on time scale T [수식] where [수식] and [수식] may be singular at t = a, y = 0, and g(t, x) may be singular at t = a. The arguments are based upon a fixed-point theorem for mappings that are decreasing with respect to a cone. We also obtain the analogous existence results for the related nonlinear systems [수식], and [수식] satisfying similar boundary conditions.

Research on the Relationship between Level of Rural Human Capital and Urban-Rural Income Gap

Li Chunmei,Zhao Guiting 보안공학연구지원센터(IJUNESST) 2014 International Journal of u- and e- Service, Scienc Vol.7 No.2

CircKLHL2 mitigates septic lung injury via circKLHL2-miR-338-3p-ATF6 ceRNA pathway

Zhang Chunmei,Wu Ruoran,Zhao Zhongyan 대한독성 유전단백체 학회 2024 Molecular & cellular toxicology Vol.20 No.2

Background Circular RNAs (circRNAs) are newly identified therapeutic targets for sepsis. CircRNA mmu_circ_0001679 dysregulation is underlying the pathogenesis and treatment of sepsis-induced acute lung injury (ALI). Here, the expression and role of its human homologoue circRNA-Kelch-like family member 2 (circKLHL2; hsa_circ_0071374) were explored in lipopolysaccharide (LPS)-induced human ALI. Objective Expression levels of circKLHL2, microRNA (miR)-338-3p and activating transcription factor 6 (ATF6) were detected by quantitative PCR and western blotting, and dual-luciferase reporter assay confirmed target relationships among them. Cell injury was measured using cell-counting kit-8, reactive oxygen species (ROS)/malondialdehyde (MDA)/superoxide dismutase (SOD) assays, Annexin V-fluorescein isothiocyanate apoptosis assay, western blotting and cysteine-requiring aspartate proteases (caspases) activity assays. Result The expression of circKLHL2 and ATF6 was upregulated in sepsis-damaged human lung tissues and LPS-stressed human bronchial epithelial cells (16HBE), with a concomitant decrease of miR-338-3p. RNA interfering of circKLHL2 improved cell viability of LPS-challenged 16HBE cells, and suppressed apoptosis, oxidative stress and endoplasmic reticulum (ER) stress, as evidenced by the increased bcl-2 level and SOD activity, and the decreased apoptosis rate, caspase3/9 activity and levels of bcl-2-associated X protein, ROS, MDA, ATF6 and C/EBP-homologous protein. Moreover, circKLHL2 knockdown exerted similar results to ER stress inhibitor 4-phenyl butyric acid in LPS injury. In addition, circKLHL2 knockdown reversed LPS-induced mitochondrial dysfunction. ATF6 and circKLHL2 were competing endogenous RNAs of miR-338-3p, and either exhausting miR-338-3p or restoring ATF6 could counteract circKLHL2 knockdown-mediated roles in LPS injuries. Conclusion Depleting circKLHL2 suppressed LPS-induced ALI through suppressing mitochondrial dysfunction and cytotoxicity and oxidative and ER stresses-induced apoptosis via circKLHL2-miR-338-3p/ATF6 axis.

Fast Ambiguity Resolution using Galileo Multiple Frequency Carrier Phase Measurement

Shengyue Ji,Wu Chen,Chunmei Zhao,Xiaoli Ding,Yongqi Chen 한국항해항만학회 2006 한국항해항만학회 학술대회논문집 Vol.1 No.-

Rapid and high-precision positioning with a Global Navigation Satellite System (GNSS) is feasible only when very precise carrier-phase observations can be used. There are two kinds of mathematical models for ambiguity resolution. The first one is based on both pseudorange and carrier phase measurements, and the observation equations are of full rank. The second one is only based on carrier phase measurement, which is a rank-defect model. Though the former is more commonly used, the latter has its own advantage, that is, ambiguity resolution will be freed from the effects of pseudorange multipath. Galileo will be operational. One of the important differences between Galileo and current GPS is that Galileo will provide signals in four frequency bands. With more carrier-phase data available, frequency combinations with long equivalent wavelength can be formed, so Galileo will provide more opportunities for fast and reliable ambiguity resolution than current GPS. This paper tries to investigate phase only fast ambiguity resolution performance with four Galileo frequencies for short baseline. Cascading Ambiguity Resolution (CAR) method with selected optimal frequency combinations and LAMBDA method are used and compared. To validate the resolution, two tests are used and compared. The first one is a ratio test. The second one is lower bound success-rate test. The simulation test results show that, with LAMBDA method, whether with ratio test or lower bound success rate validation criteria, ambiguity can be fixed in several seconds, 8 seconds at most even when 1 sigma of carrier phase noise is 12 mm. While with CAR method, at least about half minute is required even when 1 sigma of carrier phase noise is 3 mm. It shows that LAMBDA method performs obviously better than CAR method.

Synthesis of sulfonated catalyst from bituminous coal to catalyze esterification for biodiesel production with promoted mechanism analysis

Tang Xincheng,Niu Shengli,Zhao Shuang,Zhang Xiangyu,Li Ximing,Yu Hewei,Lu Chunmei,Han Kuihua 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.77 No.-

The carbon-based heterogeneous acid catalyst is synthesized from bituminous coal through the partialcarbonization and sulfonation method and applied to catalyze the esterification of oleic acid withmethanol for biodiesel production. Various characterization methods are used to explain catalyticfeatures and molecular simulation is conducted to analyze the promoted mechanism of acid catalyst inesterification. Carbon catalyst, prepared by partially carbonized at 350 C and sulfonated at 105 C,catalyzes esterification with biodiesel yield of 98.70%. Transition state analysis implies that acid catalystreduces the activation energy through providing proton to promote esterification.

RNA-seq analysis reveals the role of a small GTP-binding protein,Rab7, in regulating clathrin-mediated endocytosis and salinity-stress resistance in peanut

Jiongming Sui,Guan Li,Guanxu Chen,Chunmei Zhao,Xiangyuan Kong,Xiaomin Hou,Lixian Qiao,Jingshan Wang 한국식물생명공학회 2017 Plant biotechnology reports Vol.11 No.1

Small GTP-binding proteins, Rab7, are known to be responsive to abiotic stresses in plants, but the molecular mechanism is poorly understood. To investigate how AhRab7 increases resistance to salinity stress in peanut, this study compared a transgenic genotype (S5) that overexpressed the AhRab7 gene and that had high salinity resistance with a non-transgenic genotype (S7) that had low salinity resistance. Digital gene expression (DGE) sequencing was performed with leaves of S5 and S7 before and after salinity-stress treatment. In total, 2697 differentially expressed genes (DEGs) were identified between S5 and S7, and KEGG enrichment analyses showed that the DEGs are involved pathways including endocytosis, lysosome, hormone signaling, phosphatidylinositol signaling, calcium, and others. Among them, 164 were differentially regulated after salinity-stress treatment. Of 164 DEGs, 110 were responsive to salinity stress in S5 and/or S7. The 110 DEGs included genes that encode the following kinds of transcription factors and proteins known to be involved in resistance to salinity stress: WRKY, NAC, MYM-type zinc finger, late embryogenesis abundant proteins, lipid transfer protein, 1-cys peroxiredoxin, aquaporin, oleosin, and others. AhRab7 gene might mediate signaling pathways including phosphatidylinositol, calcium, abscisic acid, etc., and then regulate the expression of transcription factors and downstream genes for ROS scavenging in peanut. The results of this study will be useful for further investigations of the mechanism underlying the role of the AhRab7 gene in resistance to salinity stress in peanut.

Investigation of supplementation with a combination of fermented bean dregs and wheat bran for improving the growth performance of the sow

Junze Liu,Kai Wang,Liangyu Zhao,Yansen Li,Zhaojian Li,Chunmei Li 한국축산학회 2024 한국축산학회지 Vol.66 No.2

To investigate the effect of dietary supplementation with a fermented mixture of bean dregs and wheat bran (FBW) on sow performance. FBW was given to sows during late gestation and lactation; in total, 24 sows were randomly assigned to 4 groups (control diet; 3% FBW diet; 6% FBW diet; 9% FBW diet, n = 6). The weight ratio of bean dregs (wet) to wheat bran was 4:6. Sows were fed different diets from 85 d of gestation until weaning. The results showed that supplementation with FBW increased average daily feed intake (ADFI) during lactation (p < 0.05). FBW supplementation also increased litter weight and milk yield (p < 0.05). The contents of Escherichia coli in the feces of the treatment groups were significantly reduced by FBW supplementation (p < 0.01). FBW supplementation significantly improved the fecal morphology (p < 0.05), alleviating sows’ constipation. In conclusion, FBW could increase the ADFI, improve lactation and piglet litter weight in sows and reduce the pathogenic bacterial content in sow feces and constipation.

On TEC anomalies as precursor before MW 8.6 Sumatra earthquake and MW 6.7 Mexico earthquake on April 11, 2012

Jinyun Guo,Wang Li,Xin Liu,Jianbo Wang,Xiaotao Chang,Chunmei Zhao 한국지질과학협의회 2015 Geosciences Journal Vol.19 No.4

To investigate the coupling relationship between earthquake and ionosphere perturbation, we process the global total electron contents (TECs) estimated from GPS data of IGS stations by CODE and analyze TEC anomalies before MW 8.6 Sumatra earthquake and MW 6.7 Mexico earthquake on April 11, 2012. The sliding interquartile method with the sliding window of 27 days is used to process data of SSN, F10.7 solar flux, Dst and Kp to eliminate the effects of solar activity and the geomagnetic activity. The results show that there are positive and negative TEC anomalies over epicenter on the 11th day and the 3rd day prior to the Sumatran earthquake respectively. But the decrement and increment of TEC anomalies over epicenter occurred on the 11th day and the 3rd day prior to the Mexico earthquake. The global TEC anomalies are analyzed on the 11th day and the 3rd day before these two great earthquakes, respectively. The magnitudes of TEC anomaly occurred on the 3rd day before earthquakes are larger than that occurred on the 11th day before earthquakes. This indicates the magnitude of anomaly may be related to the number of days prior to earthquake. But the magnitude of TEC anomaly near Sumatran is lower than that near Mexico, and the duration of anomalies occurred on 11th day is longer than those on 3rd day prior to earthquake, which are different from previous results. The TEC anomaly of Sumatran earthquake mainly occurs in the afternoon and night local time, but the TEC anomaly of Mexico earthquake mainly occurs in the morning local time. The TEC anomaly peak regions before these two earthquakes appeared on the south of epicenters instead of the vertical projection of the epicenter. Corresponding ionospheric anomalies are also observed in the magnetically conjugated regions. These can be guidance for the ionosphere monitoring in earthquake study.