Surface formation and damage mechanisms of nano-ZrO 2 ceramics under axial ultrasonic-assisted grinding

Yanyan Yan,Yafei Zhang,Bo Zhao,Junli Liu 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.3

In this study, the surface formation and damage mechanism of hard-brittle materials in axial ultrasonic-assisted grinding (AUAG) were revealed using the grinding force and grinding force ratio. Theoretical analysis presented that the grinding force and grinding force ratio in AUAG are relatively small. AUAG is a machining method with a large tangential force and a small normal force, which can promote the removal of hard-brittle materials and reduce the surface and subsurface damage (SSD). Scratching and grinding tests of nano-ZrO 2ceramics were conducted to validate the theoretical analysis. The results demonstrated that the periodic tangential force under the AUAG promotes the nucleation and propagation of shallower lateral micro-cracks, thereby allowing the easier removal of hard-brittle materials. Additionally, the proportion of brittle fracture was less, and the surface roughness and maximum SSD depth were significantly small. Therefore, AUAG is a suitable ultra-precision machining technique for hard-brittle materials.

Molecular and phylogenetic analysis of Anaplasma spp. in sheep and goats from six provinces of China

Yan Zhang,Yali Lv,Feifei Zhang,Wenjing Zhang,Jinhong Wang,Yanyan Cui,Rongjun Wang,Fuchun Jian,Longxian Zhang,Changshen Ning 대한수의학회 2016 Journal of Veterinary Science Vol.17 No.4

Members of the genus Anaplasma are important emerging tick-borne pathogens in both humans and animals in tropical and subtropical areas. Here, we investigated the presence of Anaplasma spp. in 621 sheep and 710 goats from six provinces of China. Polymerase chain reaction(PCR) and DNA sequencing were conducted to determine the prevalence of Anaplasma (A.) phagocytophilum, A. ovis and A. bovis targetingthe 16S ribosomal RNA or the major surface protein 4 gene. PCR revealed Anaplasma in 39.0% (240/621) of sheep and 45.5% (323/710)of goats. The most frequently detected species was A. ovis (88/621, 14.2% for sheep; 129/710, 18.2% for goats), followed by A. bovis (60/621,9.7% for sheep; 74/710, 10.4% for goats) and A. phagocytophilum (33/621, 5.3% for sheep; 15/710, 2.1% for goats). Additionally, eight sheepand 20 goats were found to be infected with three pathogens simultaneously. DNA sequencing confirmed the presence of these three Anaplasmaspecies in the investigated areas, and phylogenetic analysis indicated that there was geographic segregation to a certain extent, as well as arelationship between the host and cluster of A. ovis. The results of the present study provide valuable data that helps understand theepidemiology of anaplasmosis in ruminants from China.

Preparation and In Vitro Characterization of Gelatin Methacrylate for Corneal Tissue Engineering

Yan Yayun,Cao Yanyan,Cheng Rong,Shen Zhizhong,Zhao Yajing,Zhang Yixia,Zhou Guohong,Sang Shengbo 한국조직공학과 재생의학회 2022 조직공학과 재생의학 Vol.19 No.1

BACKGROUND: Corneal disease is second only to cataract considered as the leading cause of blindness in the world, with high morbidity. Construction of corneal substitutes in vitro by tissue engineering technology to achieve corneal regeneration has become a research hotspot in recent years. We conducted in-depth research on the biocompatibility, physicochemical and mechanical properties of rat bone marrow mesenchymal stem cells (rBM-MSCs)-seeded gelatin methacrylate (GelMA) as a bioengineered cornea. METHODS: Four kinds of GelMA with different concentrations (7, 10, 15 and 30%) were prepared, and their physicchemical, optical properties, and biocompatibility with rBM-MSCs were characterized. MTT, live/dead staining, cell morphology, immunofluorescence staining and gene expression of keratocyte markers were performed. RESULTS: 7%GelMA hydrogel had higher equilibrium water content and porosity, better optical properties and hydrophilicity. In addition, it is more beneficial to the growth and proliferation of rBM-MSCs. However, the 30%GelMA hydrogel had the best mechanical properties, and could be more conducive to promote the differentiation of rBM-MSCs into keratocyte-like cells. CONCLUSION: As a natural biological scaffold, GelMA hydrogel has good biocompatibility. And it has the ability to promote the differentiation of rBM-MSCs into keratocyte-like cells, which laid a theoretical and experimental foundation for further tissue-engineered corneal stromal transplantation, and provided a new idea for the source of seeded cells in corneal tissue engineering.

Cloning and characterization of hemerythrin gene from Sipuncula Phascolosoma esculenta

Yan Liu,Chenghua Li,Xiurong Su,Mengqian Wang,Yanyan Li,Ye Li,Taiwu Li 한국유전학회 2013 Genes & Genomics Vol.35 No.1

Hemerythrin is a non-heme respiratory protein involved in oxygen storage and transport in invertebrates. In the present study, the hemerythrin cDNA was cloned from Phascolosoma esculenta (denoted as PeHr) by PCR and rapid amplification of cDNA ends approaches. The full-length PeHr consisted of 770 bp containing of a 50-terminal untranslated region (UTR) of 83 bp, a 30-terminal UTR of 327 bp, and a coding domain sequence of 360 bp encoding a polypeptide of 120 amino acids with estimated molecular mass of 13.6 kDa and theoretical isoelectric point of 5.78. The expression profiles of PeHr were evaluated by real-time RT-PCR under blood loss stress. The expression level of PeHr was significantly up-regulated from 45 to 48 h, then slightly recovered to its original level. The coding sequence of the PeHr was cloned and expressed in Escherichia coli BL21 (DE3) for antibodies preparation. Western blotting analysis conformed that the generated antibodies could specifically identify not only recombinant product, but also native protein from the total protein extraction. Our results indicated that PeHr might be involved into haemocytes regeneration, and its function roles should be further investigated by the generated antibodies.

Detecting the origin of luminescence in Er³⁺-doped hexagonal Na_1.5Gd_1.5F₆ phosphors

Wang, Xiangfu,Bu, Yanyan,Yan, Xiaohong,Cai, Peiqing,Wang, Jing,Qin, Lin,Vu, Thiquynh,Seo, Hyo Jin OPTICAL SOCIETY OF AMERICA 2016 Optics letters Vol.41 No.22

<P>Understanding site-selective fluorescence is one of valuable importance for spectrum modulation. In this Letter, we observed the existence of two non-equivalent Gd-activated crystallographic sites in an Er3+-doped hexagonal Na1.5Gd1.5F6 phosphor. It is proved that two green emissions from the S-4(3/2) level separately originate from the Gd1 (540 nm) and Na2/Gd2 (550-555 nm) crystallographic sites, and the 657 nm red emission from the F-4(9/2) level only originates from Na2/Gd2 site through using the time-resolved luminescence spectra. The 142.2% absolute enhancement of the red emission is realized through the synergistic effect of ultraviolet downconversion and infrared upconversion induced by the 370 nm and 1.54 mu m dual-mode excitation. (C) 2016 Optical Society of America</P>

Genomic location and expression analysis of expansin gene family reveals the evolutionary and functional significance in Triticum aestivum

Hanfeng Ding,Nana Li,Yanyan Pu,Yongchao Gong,Yanli Yu 한국유전학회 2016 Genes & Genomics Vol.38 No.11

The plant-specific expansin proteins constitute an ancient and major gene family known to have roles in regulating diverse biological processes in plants. Although the functions of many expansin genes have been identified in wheat and other species, little is known about the evolution and genomic locations of the expansin genes in wheat (Triticum aestivum). In this study, a total of 87 expansin genes were identified in the wheat genome, including 52 EXPAs, 42 EXPBs and 4 EXLAs. The EXLB gene was not found in the wheat genome. Phylogenetic tree and comparative analysis revealed amplification of the EXPBs in rice, maize and wheat. The predicted wheat expansins were distributed across 14 of 21 chromosomes with different densities, 3 tightly co-located clusters and 15 paralogous pairs, indicating that tandem duplication and segmental duplication events also played roles in the evolution of expansins in wheat. In addition, the gene structures and conserved protein domains of wheat expansins suggest high levels of conservation within the phylogenetic subgroups. Analysis of a published microarray database showed that most wheat expansin genes exhibit different expression levels in different tissues and developmental stages. To our knowledge, this is the first report of a genome- wide analysis of the wheat expansin gene family, which should provide valuable information for further elucidating the classification and putative functions of the entire gene family.

A Gel-like Comb Micro-Block Hydrophobic Associating Polymer: Synthesis, Solution Property and the Sol-Gel Transition at Semi-Dilute Region

Wanfen Pu,Feng Jiang,Bing Wei,Yanli Tang,Yanyan He 한국고분자학회 2017 Macromolecular Research Vol.25 No.2

The gel-like comb micro block hydrophobic associating polymer (CBHAP) was synthesized by mixed micellar polymerization. The chemical structure of the copolymer was characterized by Fourier transform infrared spectroscopy (FT-IR). The rheological properties of CBHAP in fresh water and saline water at semi-dilute region were investigated. The experimental results show that, because of the intermolecular forces, shear thickening phenomenon can be observed obviously in brine solution and the Newtonian viscosity plateau could be observed clearly before 40 s-1. When the concentration reaches 3,000 mg/L, the G’ and G’’ becomes stable, indicating that CBHAP experiences the sol-gel transition after 3,000 mg/L. However, the curl structure is formed by adding salt, resulting in a higher concentration of the sol-gel transition than that in fresh water. Once the curl structure is destroyed by shearing or stretching, the intermolecular forces will take into effect and complete the sol-gel transition at semi-dilute region.

Two new triterpenoid saponins derived from the leaves of Panax ginseng and their antiinflammatory activity

Li, Fu,Cao, Yufeng,Luo, Yanyan,Liu, Tingwu,Yan, Guilong,Chen, Liang,Ji, Lilian,Wang, Lun,Chen, Bin,Yaseen, Aftab,Khan, Ashfaq A.,Zhang, Guolin,Jiang, Yunyao,Liu, Jianxun,Wang, Gongcheng,Wang, Ming-Kui The Korean Society of Ginseng 2019 Journal of Ginseng Research Vol.43 No.4

Background: The leaves and roots of Panax ginseng are rich in ginsenosides. However, the chemical compositions of the leaves and roots of P. ginseng differ, resulting in different medicinal functions. In recent years, the aerial parts of members of the Panax genus have received great attention from natural product chemists as producers of bioactive ginsenosides. The aim of this study was the isolation and structural elucidation of novel, minor ginsenosides in the leaves of P. ginseng and evaluation of their antiinflammatory activity in vitro. Methods: Various chromatographic techniques were applied to obtain pure individual compounds, and their structures were determined by nuclear magnetic resonance and high-resolution mass spectrometry, as well as chemical methods. The antiinflammatory effect of the new compounds was evaluated on lipopolysaccharide-stimulated RAW 264.7 cells. Results and conclusions: Two novel, minor triterpenoid saponins, ginsenoside $LS_1$ (1) and 5,6-didehydroginsenoside $Rg_3$ (2), were isolated from the leaves of P. ginseng. The isolated compounds 1 and 2 were assayed for their inhibitory effect on nitric oxide production in LPS-stimulated RAW 264.7 cells, and Compound 2 showed a significant inhibitory effect with $IC_{50}$ of $37.38{\mu}M$ compared with that of NG-monomethyl-L-arginine ($IC_{50}=90.76{\mu}M$). Moreover, Compound 2 significantly decreased secretion of cytokines such as prostaglandin $E_2$ and tumor necrosis factor-${\alpha}$. In addition, Compound 2 significantly suppressed protein expression of inducible nitric oxide synthase and cyclooxygenase-2. These results suggested that Compound 2 could be used as a valuable candidate for medicinal use or functional food, and the mechanism is warranted for further exploration.

Functional roles and mechanisms of ginsenosides from Panax ginseng in atherosclerosis

Qianqian Xue,Ningning He,Zhibin Wang,Xiuxiu Fu,Lynn Htet Htet Aung,Yan Liu,Min Li,Jae Youl Cho,Yanyan Yang,Tao Yu 고려인삼학회 2021 Journal of Ginseng Research Vol.45 No.1

Atherosclerosis (AS) is a leading cause of cardiovascular diseases (CVDs) and it results in a high rate of death worldwide, with an increased prevalence with age despite advances in lifestyle management and drug therapy. Atherosclerosis is a chronic progressive inflammatory process, and it mainly presents with lipid accumulation, foam cell proliferation, inflammatory response, atherosclerotic plaque formation and rupture, thrombosis, and vascular calcification. Therefore, there is a great need for reliable therapeutic drugs or remedies to cure or alleviate atherosclerosis and reduce the societal burden. Ginsenosides are natural steroid glycosides and triterpene saponins obtained mainly from the plant ginseng. Several recent studies have reported that ginsenosides have a variety of pharmacological activities against several diseases including inflammation, cancer and cardiovascular diseases. This review focuses on describing the different pharmacological functions and underlying mechanisms of various active ginsenosides (Rb1,-Rd, -F, -Rg1, -Rg2, and -Rg3, and compound K) for atherosclerosis, which could provide useful insights for developing novel and effective anti-cardiovascular drugs.

Retrospective Electrocardiography-Gated Real-Time Cardiac Cine MRI at 3T: Comparison with Conventional Segmented Cine MRI

Chen Cui,Gang Yin,Minjie Lu,Xiuyu Chen,Sainan Cheng,Lu Li,Weipeng Yan,Yanyan Song,Sanjay Prasad,Yan Zhang,Shihua Zhao 대한영상의학회 2019 Korean Journal of Radiology Vol.20 No.1

Objective: Segmented cardiac cine magnetic resonance imaging (MRI) is the gold standard for cardiac ventricular volumetric assessment. In patients with difficulty in breath-holding or arrhythmia, this technique may generate images with inadequate quality for diagnosis. Real-time cardiac cine MRI has been developed to address this limitation. We aimed to assess the performance of retrospective electrocardiography-gated real-time cine MRI at 3T for left ventricular (LV) volume and mass measurement. Materials and Methods: Fifty-one patients were consecutively enrolled. A series of short-axis cine images covering the entire left ventricle using both segmented and real-time balanced steady-state free precession cardiac cine MRI were obtained. End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF), and LV mass were measured. The agreement and correlation of the parameters were assessed. Additionally, image quality was evaluated using European CMR Registry (Euro-CMR) score and structure visibility rating. Results: In patients without difficulty in breath-holding or arrhythmia, no significant difference was found in Euro-CMR score between the two techniques (0.3 ± 0.7 vs. 0.3 ± 0.5, p > 0.05). Good agreements and correlations were found between the techniques for measuring EDV, ESV, EF, SV, and LV mass. In patients with difficulty in breath-holding or arrhythmia, segmented cine MRI had a significant higher Euro-CMR score (2.3 ± 1.2 vs. 0.4 ± 0.5, p < 0.001). Conclusion: Real-time cine MRI at 3T allowed the assessment of LV volume with high accuracy and showed a significantly better image quality compared to that of segmented cine MRI in patients with difficulty in breath-holding and arrhythmia.