Differences in the methanogen community between the nearshore and offshore sediments of the South Yellow Sea

Chen Ye,Zhen Yu,Wan Jili,Yin Xia,Li Siqi,Liu Jiayin,Zhang Guodong,Mi Tiezhu 한국미생물학회 2022 The journal of microbiology Vol.60 No.8

The differences in methanogen abundance and community composition were investigated between nearshore and offshore sediments in the South Yellow Sea (SYS). Shannon, Simpson, and Chao1 indices revealed a higher diversity of methanogens in the nearshore sediments than in the offshore sediments. The Mann–Whitney U test demonstrated that the relative abundance of Methanococcoides was significantly higher in the offshore sediments, while the relative abundances of Methanogenium, Methanosarcina, Methanosaeta, Methanolinea, and Methanomassiliicoccus were significantly higher in the nearshore sediments (P < 0.05). The abundance of the mcrA gene in the nearshore sediments was significantly higher than that in the offshore sediments. Furthermore, a similar vertical distribution of the methanogen and sulfatereducing bacteria (SRB) abundances was observed in the SYS sediments, implying there is potential cooperation between these two functional microbes in this environment. Finally, total organic carbon (TOC) was significantly correlated with methanogen community composition.

Effect of aberrantly methylated androgen receptor target gene PCDH7 on the development of androgen-independent prostate cancer cells

Siqi Xu,Xiaoyan Wu,Zhihua Tao,Hongsheng Li1,Chenliang Fan,Songjin Chen,Jianwei Guo,Yao Ning,Xuqi Hu 한국유전학회 2020 Genes & Genomics Vol.42 No.3

Background Androgen-independent prostate cancer (AIPC) is an extremely malignant tumor developed from the androgen dependent (ADPC). However, the mechanism of transition process from ADPC to AIPC remains unknown. Objective Here we aimed to identify the androgen receptor (AR) target gene and its roles in AIPC. Methods Target genes of AR were identified by ChIP-seq in AIPC cells. AR target gene PCDH7 was detected by real time PCR and western blot. Methylation of PCDH7 was measured by bisulfite sequencing and bisulfite amplicon sequencing. Cell growth, invasion and apoptosis were measured by CCK-8, transwell and flow cytometry, respectively. Results AR was significantly enriched in the upstream of PCDH7 gene. The expression of PCDH7 was significantly decreased, while the methylation of PCDH7 was increased in the AIPC cells compared to the ADPC cells. DNA methyltransferase inhibitor significantly suppressed the methylation and increased the mRNA and protein level of PCDH7. Moreover, overexpression of DNMT1 remarkably reduced the mRNA and protein level of PCDH7. DNA methyltransferase inhibitor decreased the cell growth and invasion while promote the cell apoptosis in the AIPC cells. AR significantly target PCDH7, whose hypermethylation may repress cell growth and invasion, and promote apoptosis in AIPC. Conclusions This study might provide a novel potential target for the treatment of AIPC.

Highly efficient separation of uranium from wastewater by in situ synthesized hydroxyapatite modified coal fly ash composite aerogel

Siqi Huang,Congcong Chen,Zhibo Zhao,Lingyi Jia,Yong Zhang 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.118 No.-

In this work, hydroxyapatite (HAP) was in situ synthesized on coal fly ash (CFA) to prepare hydroxyapatitemodified coal fly ash composite aerogel (HCFAA). The maximum removal efficiency and capabilityof uranium(VI) on HCFAA were 97.6 % and 205.7 mg g1, respectively, which was much higher than thoseof CFA (83.6 % and 59.1 mg g1) (pH = 3.0, m/V = 1.0 g/L and T = 298 K). The desorption efficiency of uranium(VI) by HCFAA was even more than 80 % after five cycles, demonstrating that the introduction ofHAP had improved uranium(VI) removal performances. Pseudo-second-order and Langmuir models werefitted better with the experimental data, indicating the uranium(VI) removal process was a homogeneousmonolayer chemisorption. Meanwhile, the uranium(VI) removal efficiency for HCFAA in actual wastewaterwas higher to 80.6 % and uranium(VI) could even be completely separated from actual wastewaterby HCFAA during dynamic adsorption (m = 50 mg, V = 400 mL, C0 = 10 mg/L), further illustrating that theintroduction of HAP was an available method to modify CFA. Characterizations results demonstrated thaturanium(VI) was successfully immobilized on HCFAA through ion exchange, dissolution-precipitationand surface complexation. In conclusion, HCFAA was a prospective adsorbent for uranium(VI) separationin practical application.

미-중 무역분쟁이 해당국 주식시장에 미치는 영향에 관한 연구

정진호,Siqi Chen,이지선 경희대학교(국제캠퍼스) 국제지역연구원 2020 아태연구 Vol.27 No.4

This study provides an empirical analysis of the US-China trade war impacts on its stock markets. Using 20 years of daily return series of S&P 500 and SSE Composite Indices from 2000 and 2019, we investigate volatility clustering, asymmetric volatility under EGARCH and TGARCH models that effectively captures the time-varying volatility in the pre- and the post-trade war eras. We found the following results. First, volatility clustering is significant during the pre-trade war period for both the US and Chinese stock markets. However, the level of clustering was increased in the US and decreased in China during the post-trade war period, implying that the US stock market responded more sensitive relative to Chinese stock market. Second, the volatility persistence in US was decreased while it was increased in China during the US-China trade war period. The results suggest that US Federal Reserve’s active stabilization policies help quickly absorb the trade war shock. Third, the presence of asymmetric volatility in the pre-trade war period was identified both in the US and Chinese stock markets. However, the degree of asymmetry in China is lower than that of US. More importantly, in China, asymmetric volatility is not significant in the post-trade war period, suggesting the insensitive responses of Chinese investors to debt ratio and risk premium increase during the market turmoil. Finally, the possibility of adverse asymmetric volatility in Chinese stock market is discovered during the trade war period, suggesting that Chinese investors respond more sensitively to good news than bad news. Overall, the government’s active engagement seems to be effective for market stabilization during the market turbulence in US. In addition, we found the possibility of speculative investment increase in China because of adverse asymmetric volatility in Chinese stock market. 본 연구에서는 최근 미-중 무역분쟁이 해당국의 주식시장에 미친 영향을 실증적으로 분석하였다. 2000년부터 2019년까지 주가지수 자료를 이용하여 무역분쟁 전후 변동성 군집현상, 비대칭적 변동성 등을 시간-가변 변동성 모형인 EGARCH, TGARCH 모형을 통해 동태적으로 분석하였다. 주요한 결과는 다음과 같다. 첫째, 미-중 각 주식시장에서 변동성 군집현상이 관찰되었으나, 무역분쟁 이후 그 강도는 미국 시장에서 증가한 반면 중국 시장에서 감소하여 미국 시장이 중국 시장 대비 충격에 더욱 민감하게 반응하였음을 나타냈다. 둘째, 무역분쟁 이후 미국 시장의 변동성 지속성은 감소한 반면 중국 시장에서는 증가하였음을 발견하였다. 셋째, 무역분쟁 이후 중국 주식시장의 비대칭 변동성은 유의하지 않았으며 무역분쟁 이전 존재한 비대칭 변동성의 정도 또한 미국 시장 대비 약한 것으로 나타나, 중국 시장에서는 위기 시 주가 하락에 따른 부채비율 상승 및 위험프리미엄 상승에 투자자들이 민감하게 반응하지 않았음을 확인하였다. 넷째, 무역분쟁 이후 중국 주식시장에서 역의 비대칭 변동성이 약하지만 존재하는 것으로 나타나 무역분쟁 이후 중국 시장에서 악재보다는 호재에 더욱 민감하게 반응하는 투기성향이 증가될 가능성이 발견되었다. 이상의 결과를 종합하여 볼 때, 무역분쟁과 같은 시장 혼란 발생 시 정부의 적극적 개입은 시장 안정화에 효과적으로 작용할 수 있으며, 선진 주식시장과 다르게 중국시장의 투자자들은 모멘텀전략보다는 역행투자전략을 추종하는 투자행태가 효과적일 가능성을 발견하였다.

Hepatitis B virus X protein-mediated non-coding RNA aberrations in the development of human hepatocellular carcinoma

Bei Zhang,Siqi Han,Bing Feng,Xiaoyuan Chu,Longbang Chen,Rui Wang 생화학분자생물학회 2017 Experimental and molecular medicine Vol.49 No.-

Hepatitis B virus (HBV) has an important role in the development of human hepatocellular carcinoma (HCC). Accumulated evidence has shown that HBV-encoded X protein (HBx) can induce both genetic alterations in tumor suppressor genes and oncogenes, as well as epigenetic aberrations in HCC pathogens. Non-coding RNAs (ncRNAs) mainly include microRNAs and long non-coding RNAs (lncRNAs). Although ncRNAs cannot code proteins, growing evidence has shown that they have various important biological functions in cell proliferation, cell cycle control, anti-apoptosis, epithelial–mesenchymal transition, tumor invasion and metastasis. This review summarizes the current knowledge regarding the mechanisms and emerging roles of ncRNAs in the pathogenesis of HBV-related HCC. Accumulated data have shown that ncRNAs regulated by HBx have a crucial role in HBV-associated hepatocarcinogenesis. The findings of these studies will contribute to more clinical applications of HBV-related ncRNAs as potential diagnostic markers or as molecular therapeutic targets to prevent and treat HBV-related HCC.

The Improved Wavelet Threshold Function and Its Application

DENG Caixia,CHEN Xiaxia,LI Siqi,XU Yanxin 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.7

Images will produce noise in the process of storage and collection. Wavelet threshold de-noising is a simple and effective de-noising method, but the choice of threshold function is a key. The hard-threshold function is discontinuous and there is the deviation between the signal processed by the soft-threshold function and the real signal, so this paper constructs a new threshold function at the origin sufficiently smooth to deal with above problems. A parameter is added to the new threshold function, which is between the soft-threshold and hard-threshold function by adjusting the parameter. The new threshold function can remove the noise effectively, and the image information is well preserved. Hence it plays an important role in follow-up edge detection. The de-noising method with improved wavelet threshold is presented, and then uses morphological edge detection on the new image in this paper. The result shows that the method can detect the complete edge effectively, and the visual effect and objective evaluation are good.

A flexible film type EMAT for inspection of small diameter pipe

Cuixiang Pei,Pan Xiao,Siqi Zhao,Zhenmao Chen,Toshiyuki Takagi 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.8

Pipe structures are widely applied in industries, and different kinds of defects may occur in the structures during their long-time service. For non-destructive testing of defects in pipes of small diameter, it has to be conducted from the inner side of the pipe when there is no space for detection from the outside or the geometry of the outside tube surface is too complicated. In this work, a flexible film type Electromagnetic acoustic transducer (EMAT) probe with a dual coil configuration is developed. The new probe is flexible and can be inserted into the pipe for inspection. First, the feasibility of the new probe was studied through numerical simulation. Then the feasibility of the proposed flexible EMAT for detection of wall thinning in small diameter pipe was verified experimentally. It was found that the new EMAT method is suitable for the detection of wall thinning defects for small pipes.

Comparative portrayal of ocular surface microbe with and without dry eye

ZhenHao Li,Yufang Gong,ShuZe Chen,SiQi Li,Yu Zhang,HuiMin Zhong,ZhouCheng Wang,YiFan Chen,QiXin Deng,YuTing Jiang,LiYing Li,Min Fu,GuoGuo Yi 한국미생물학회 2019 The journal of microbiology Vol.57 No.11

To compare the ocular surface (OS) microbial communities and diversity between dry eye (DE) and non-DE (NDE). Furthermore, we compared meibomian gland dysfunction (MGD) and non-MGD (NMGD) among DE subjects. The V3-V4 region of 16S rRNA gene high-throughput sequencing was performed in the conjunctival swab samples to investigate the composition of the OS bacterial community in DE (n=35) and NDE (n=54) and compared the composition of MGD (n=25) and NMGD (n=10) among DE subjects. Deep sequencing of OS 16S rDNA from DE (n=35) and NDE (n=54) demonstrated great a difference in alpha and beta diversity between the OS bacterial flora (P < 0.05). The similar OS microbial structures were shown at the phylum and genus levels by bioinformatics analysis between them, and in LEfSe (linear discriminant analysis effect size) analysis, Bacteroidia and Bacteroidetes were enriched in DE, while Pseudomonas was plentiful in NDE (linear discriminant analysis [LDA] > 4.0). Among the DE group, there was no significant difference in α and β diversity between MGD and NMGD (P > 0.05). Surprisingly, Bacilli was the dominant microbe in MGD, and Bacteroidetes was the superior bacteria in NMGD among DE subjects (LDA > 4.0). Different diversity of OS bacteria composition between DE and NDE and the altered diversity of OS bacteria may play an important role in DE. Moreover, the lower dominance of OS bacteria in DE may be associated with the occurrence and development of DE. Although there was no significant difference in alpha and beta analysis, the OS dominant microbe between MGD and NMGD among DE was different.

Esterification of free fatty acids in a rotor-stator spinning disc reactor

Yubin Wang,Xiaoqiu Tao,Jun Li,Siqi Zhang,Yang Jin,Ming Chen 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.8

Fatty acid methyl esters (FAMEs) were produced by the esterification of free fatty acids (FFA) with methanol, and sulfuric acid as the catalyst in a rotor-stator spinning disc reactor (RSSDR). The RSSDR, which shows excellent mixing efficiency and fast phase separation, was used as a novel continuous-flow esterification reactor. The influence of the variables (e.g., rotational speed, volume flow rate, rotor-stator distance, methanol-FFA molar ratio, catalyst dosage, and temperature) on esterification conversion () and productivity of FAMEs (PFAME) were investigated. It was found that the experimental parameters have a great impact on the  and PFAME in the RSSDR system, due to the effect of micromixing intensity and residence time distribution. Furthermore, to compare with other traditional esterification reactors, the values of , PFAME, and PFAME per unit reactor volume (PFAME/VR) in the RSSDR were also employed to assess the performance for the production of FAMEs. It shows that the maximum values of PFAME, and PFAME/VR attained were 0.14mol/min and 3.06×102 mol/(mL min), respectively. Therefore, the RSSDR is proven to be an effective esterification reactor with high esterification conversion in comparison to conventional esterification reactors.

Effects of TETA or TEPA Loading on CO2 Adsorption Properties Using Pore-Expanded KIT-6 as Support

Jianwen Wei,Dejun Mei,Zhifeng Lin,Linlin Geng,Siqi Chen,Lei Liao 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.4

Mesoporous silica pore-expanded KIT-6 was synthesized using tetraethoxysilane (TEOS) as the silica source, tri-block copolymer (P123) as a structure-directing agent and 1,3,5-trimethylbenzene (TMB) as swelling agents by a hydrothermal method. Then, pore-expanded KIT-6 (PE-KIT-6) was modified with different amounts of amines including triethylenetetramine (TETA) and tetraethylenepentamine (TEPA) by a post-synthetic impregnation method. The samples were characterized by small-angle X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2 adsorption/desorption, elemental analysis and thermal gravimetric analysis (TGA). Experimental results revealed that the modifiers were introduced into the samples and the CO2 adsorption capacity increased first and then decreased with the increase of TETA/TEPA loadings. Under the same loadings of TETA/TEPA, the samples modified by TEPA exhibited better CO2 adsorption capacities than the samples modified by TETA because TEPA has one more amine group than TETA in the molecule. The results also indicated that the samples had good adsorption capacities at the loadings ranging from 30% to 35%. Among them, the sample modified by TEPA with the loading of 35% had the maximum adsorption capacity of 2.9mmol/g. After five cycles of adsorption/desorption, the adsorption capacity only dropped 4.59%, indicating that the adsorbent of PE-KIT-6 modified by TEPA has good cyclic stability.