Preparation, Curing, and Properties of Boron-Containing Bisphenol-S Formaldehyde Resin/o-Cresol Formaldehyde Epoxy Resin/Nano-SiO2 Composites

Weihong Wu,Jingjing Leng,Zheng Wang,Hongqiang Qu,Jungang Gao 한국고분자학회 2016 Macromolecular Research Vol.24 No.3

Boron-containing bisphenol-S formaldehyde resin (BBPSFR) with different amounts of nano-SiO2 by in situ formation was used to cure o-cresol formaldehyde epoxy resin (o-CFER). The curing kinetics, dynamic mechanical properties, and thermal stability of BBPSFR/o-CFER/nano-SiO2 composites (BCS) were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetry (TG), and thermogravimetrymass spectrometry (TGMS). Morphology of nano-SiO2-containing BBPSFR and glass fiber laminates of the BCS were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The mechanical properties and electrical properties were also determined. The results showed that nano-SiO2 accelerated the curing process and decreased the curing temperature; the non-isothermal curing kinetics of the BCS can be described by the two-parameter (m, n) Šesták-Berggren kinetic model, and the average value of m was 0.32 and n was 1.00. The thermal stability was enhanced by the addition of nano-SiO2, especially at higher temperatures, and the residual weight increased with increasing nano-SiO2 content. Incorporation of 6 wt% of nano-SiO2 increased the impact strength from 105 to 149 kJ/m2 and storage modulus at ambient from 6.85 to 12.7 GPa, and the TEM photograph of which showed that nano-SiO2 particles (about 50 nm) were dispersed in the matrix more uniformly. The volume resistance, Rv, and dielectric constant, ε, slightly increased when the nano-SiO2 content was 3 wt%.

Genetic variations in DROSHA and DICER and survival of advanced non-small cell lung cancer: a two-stage study in Chinese population

Shuangshuang Wu,Yun Pan,Songyu Cao,Jiali Xu,Yan Liang,Yan Wang,Lei Chen,Yunyan Wei,Chongqi Sun,Weihong Zhao,Zhibin Hu,Hongxia Ma,Hongbing Shen,Jianqing Wu 한국유전학회 2015 Genes & Genomics Vol.37 No.7

MicroRNAs (miRNA) are a class of small, noncoding RNA molecules involved in carcinogenesis. Genetic variations in miRNA processing genes may affect the biogenesis of miRNAs, and consequently affect miRNAs regulation and development and progression of human cancer. Therefore, we hypothesized that polymorphisms in two main miRNA biosynthesis genes (DROSHA and DICER) may modulate the survival of advanced non-small cell lung cancer (NSCLC) patients in China. We selected 36 common tagging SNPs in DROSHA and DICER and evaluated the associations of these SNPs with survival of advanced NSCLC patients by a two-stage study in Chinese Han population (discovery cohort: 303 patients; replication cohort: 340 patients). Thirty-six SNPs were detected in the discovery cohort and 12 promising SNPs were validated in the replication cohort. The results showed that DROSHA rs3805525 was marginally associated with the survival of NSCLC patients in the replication cohort (dominant model: HR 0.69, 95 % CI 0.46–1.03, P = 0.071), which was in the same direction as that in the discovery cohort. When combing all patients into one group, three SNPs (rs3805525, rs17410035 and rs7719497) in DROSHA showed significantly associations with NSCLC survival (additive model: HR 0.82, 95 % CI 0.68–0.99 for rs3805525; HR 0.79, 95 % CI 0.62–1.00 for rs17410035; HR 0.76, 95 % CI 0.62–0.93 for rs7719497). Additionally, the combined analysis of those three SNPs showed a significant locus-dosage effect between number of favorable alleles and death risk of NSCLC (Trend P = 0.002). Genetic variations in DROSHA might be associated with the survival of advanced NSCLC patients in Chinese population.

Microwave dielectric properties of Li3Mg2SbO5F2 oxyfluorides ceramics produced by reaction-sintering method

Pengshen Wu,Cuijin Pei,Miao Chen,Xu Gao,Weihong Liu,Guoguang Yao,Jin Liu 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.6

By a reaction-sintering approach Li3Mg2SbO5F2 oxyfluorides ceramics were prepared. The sinterability, microstructure,phase transition along with microwave dielectric performances of present ceramics were researched. A gradual phase transitionfrom cubic to orthorhombic in Li3Mg2SbO5F2 ceramics sintered above 825 °C was identified by XRD refinement analysis. The microwave dielectric performances of present ceramics were closely correlated with its phase transition process andmicrostructure. Typically, optimal microwave dielectric performances (εr ~ 8.1, τf ~ –54.0 ppm/°C, Q × f ~ 68,500 GHz (under9.2 GHz)) were achieved for 825 °C-sintered Li3Mg2SbO5F2 ceramics. Moreover, a cylindrical dielectric resonator antennafabricated from Li3Mg2SbO5F2 ceramics exhibited a maximum return loss (S11) of –30.3 dB, a maximum gain of 5.3 dB andVSWR of 1.1 at the center frequency of 11.6 GHz, and impedance bandwidth of 300 MHz (at –10 dB), respectively.

Cloning, Overexpression, and Characterization of a Metagenome-Derived Phytase with Optimal Activity at Low pH

Tan, Hao,Wu, Xiang,Xie, Liyuan,Huang, Zhongqian,Gan, Bingcheng,Peng, Weihong The Korean Society for Microbiology and Biotechnol 2015 Journal of microbiology and biotechnology Vol.25 No.6

A phytase gene was identified in a publicly available metagenome derived from subsurface groundwater, which was deduced to encode for a protein of the histidine acid phosphatase (HAP) family. The nucleotide sequence of the phytase gene was chemically synthesized and cloned, in order to further overexpress the phytase in Escherichia coli. Purified protein of the recombinant phytase demonstrated an activity for phytic acid of 298 ± 17 µmol P/min/mg, at the pH optimum of 2.0 with the temperature of 37℃. Interestingly, the pH optimum of this phytase is much lower in comparison with most HAP phytases known to date. It suggests that the phytase could possess improved adaptability to the low pH condition caused by the gastric acid in livestock and poultry stomachs.

Enhanced performance of constructed wetlands by incorporating magnetic Fe₃O₄ nanoparticles and the effects on the microbial community on the surface of the substrate

Zhou Qingwei,Wu Weihong 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.6

Constructed wetlands (CWs) have been successfully employed to treat domestic sewage, while it is reported that inconsistent and low nutrient removal efficiency has been achieved. Due to the good performance in other treatment systems, magnetic Fe₃O₄ nanoparticles (Fe₃O₄ NPs) can provide a new pathway for the nutrient removal in CWs. In this study, the influences of Fe₃O₄ NPs on the nutrient removal and variation of microbial community were investigated. The CWs with Fe₃O₄ had better NH₄<SUP>+</SUP>-N (ammonia nitrogen, 95.9%), NO₃<SUP>-</SUP>-N (nitrate nitrogen, 83.8%), and TP (total phosphorus, 90.4%) removal percentages than that without Fe₃O₄. High-throughput sequencing analysis indicated that the microbial community structure could be changed by Fe₃O₄ NPs. For example, at class level, the major bacteria such as Betaproteobacteria, Gammaproteobacteria and Deltaproteobacteria were promoted by Fe₃O₄ NPs. On the other hand, at genus level, some abundant genera disappeared, while other abundant genera became dominant in CWs with Fe₃O₄ NPs, including Desulfuromonas (3.0%), Azospirillum (1.9%), Chryseolinea (1.5%), and Desulfomicrobium (1.8%). The latter genera essentially improved the microbial community involved in the nitrogen removal. Therefore, the CWs with Fe₃O₄ NPs showed higher NH₄<SUP>+</SUP>-N and NO₃<SUP>-</SUP>-N removal percentages than that without Fe₃O₄ NPs.

Enhancing the Thermal Resistance of a Novel Acidobacteria-Derived Phytase by Engineering of Disulfide Bridges

( Hao Tan ),( Renyun Miao ),( Tianhai Liu ),( Xuelian Cao ),( Xiang Wu ),( Liyuan Xie ),( Zhongqian Huang ),( Weihong Peng ),( Bingcheng Gan ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.10

A novel phytase of Acidobacteria was identified from a soil metagenome, cloned, overexpressed, and purified. It has low sequence similarity (<44%) to all the known phytases. At the optimum pH (2.5), the phytase shows an activity level of 1,792 μmol/min/mg at physiological temperature (37°C) and could retain 92% residual activity after 30 min, indicating the phytase is acidophilic and acidostable. However the phytase shows poor stability at high temperatures. To improve its thermal resistance, the enzyme was redesigned using Disulfide by Design 2.0, introducing four additional disulfide bridges. The half-life time of the engineered phytase at 60°C and 80°C, respectively, is 3.0× and 2.8× longer than the wild-type, and its activity and acidostability are not significantly affected.