In vitro toxicity of melamine against Tetrahymena pyriformis cells

Zhengfang Wang,Liben Chen,Rashad Al-Kasir,Bo Han 대한수의학회 2011 Journal of Veterinary Science Vol.12 No.1

This study assessed the toxicity of melamine against the unicellular eukaryotic system of Tetrahymena (T.) pyriformis exposed to 0, 0.05, 0.25, 0.5, 2.5, and 5 mg/mL of melamine. Cell growth curves of different cultures, the half maximum inhibition concentration (IC_50) value of melamine, and morphological changes in cells were obtained via optical and transmission electron microscopic observation. The effects of eleven melamine concentrations, 0.25, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 and 5 mg/mL, on protein expression levels of T. pyriformis were examined using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The results showed an obvious inhibitory effect of melamine on the growth of eukaryotic cells. Cell growth dynamics indicated that the IC50 value of melamine on T. pyriformis was 0.82 mg/mL. The cellular morphology was also affected in a concentration-dependent manner, with characteristics of atrophy or cell damage developing in the presence of melamine. The relative contents of the top four main proteins corresponding to peak mass-to-charge ratios (m/z) of 4466, m/z 6455, m/z 6514, and m/z 7772 in the MALDI-TOF-MS spectra were all found to be closely correlated with the melamine concentrations. In conclusion, exposure of eukaryotic cells to melamine could inhibit cell growth, cause changes in cytomorphology and even disturb the expression of proteins in a concentrationdependent manner. The described method of examining four sensitive proteins affected by melamine was also proposed to be used in a preliminary study to identify protein biomarkers in T. pyriformis.

Morphologies and Mechanical and Thermal Properties of Highly Epoxidized Polysiloxane Toughened Epoxy Resin Composites

Songqi Ma,Weiqu Liu,Zhengfang Wang,Chaohui Hu,Chunyi Tang 한국고분자학회 2010 Macromolecular Research Vol.18 No.9

A novel highly epoxidized polysiloxane was synthesized to modify the diglycidyl ether of bisphenol-A (DGEBA). The mechanical and thermal properties as well as the morphology of the cured epoxy resins were examined by tensile testing, impact testing, fracture testing, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and environmental scanning electron microscopy (ESEM). The chemical structure of the highly epoxidized polysiloxane (HEPSO) was confirmed by Fourier transform infrared spectroscopy (FTIR), 29Si nuclear magnetic resonance spectroscopy (29Si NMR), and gel permeation chromatography (GPC). The Tg increased by approximately 8 ºC after introducing HEPSO. TGA in air showed that the initial degradation temperature for 5%weight loss (Td 5%), the temperature for 50% weight loss (Td 50%) and the residual weight percent at 800 ºC (R800)were increased after introducing HEPSO. The addition of 4 phr HEPSO2 resulted in the highest increase in tensile strength, impact strength and fracture toughness (KIC). The morphology of the fracture surfaces show that the miscibility of polysiloxane with epoxy resin increased with increasing epoxide group in HEPSO. The high epoxide groups in HEPSO can react during the curing process, and participate chemically in the crosslinking network. HEPSO is expected to improve significantly the toughness and thermal stability of epoxy resin.

Effects of Fengliao-Changweikang in Diarrheapredominant Irritable Bowel Syndrome Rats and Its Mechanism Involving Colonic Motility

( Mengdi Jia ),( Xiaofang Lu ),( Zhengfang Wang ),( Luqing Zhao ),( Shengsheng Zhang ) 대한소화기기능성질환·운동학회(구 대한소화관운동학회) 2018 Journal of Neurogastroenterology and Motility (JNM Vol.24 No.3

Background/Aims This study was designed to investigate the effect of Fengliao-Changweikang (FLCWK) in diarrhea-predominant irritable bowel syndrome (IBS-D) rats and explore its underlying mechanisms. Methods IBS-D model rats were induced by neonatal maternal separation (NMS) combined with restraint stress (RS). In in vivo experiments, the model rats were randomly divided into 5 groups: NMS + RS, FLCWK (low dose, middle dose, and high dose), and pinaverium bromide. The normal control (no handling) rats were classified as the NH group. The therapeutic effect of FLCWK was evaluated by fecal characteristics, electromyographic response and abdominal withdrawal reflex scores. In in vitro experiments, the model rats were randomly divided into 2 groups: NMS + RS, FLCWK (middle dose), and no handling rats were used as the NH group. The differences in basic tension and ACh-induced tension of isolated colonic longitudinal smooth muscle strips (CLSMs) among the 3 groups were observed. In addition, different inhibitors (nifedipine, TMB-8, L-NAME, methylene blue, and 4-AP) were pretreated to explore the underlying mechanisms. Results In in vivo experiments, fecal characteristics, electromyographic response, and abdominal withdrawal reflex scores significantly improved in the FLCWK group, compared with the NMS + RS group. In in vitro experiments, the basic tension and ACh-induced tension of CLSMs in IBS-D rats were significantly inhibited by FLCWK. After pre-treatment with different inhibitors, the ACh-induced tension of CLSMs in each group showed no significant difference. Conclusions FLCWK manifested curative effect in IBS-D rats by inhibiting colonic contraction. The underlying mechanisms may be related to regulatory pathway of nitric oxide/cGMP/Ca²⁺ and specific potassium channels. (J Neurogastroenterol Motil 2018;24:479-489)

Toughening of Epoxy Resin System Using a Novel Dendritic Polysiloxane

Songqi Ma,Weiqu Liu,Chaohui Hu,Zhengfang Wang,Chunyi Tang 한국고분자학회 2010 Macromolecular Research Vol.18 No.4

Dendritic polymers have attracted increasing attention in the field of epoxy resin toughening. This paper is the first report of the use of a novel dendritic polysiloxane (DPSO) bearing high epoxide groups to modify the diglycidyl ether of bisphenol-A (DGEBA). The thermal properties, toughness and morphology of the cured epoxy resins were examined by DSC, TGA, impact testing and SEM. The chemical structure of DPSO was confirmed by FTIR, 29Si NMR and GPC. The Tg increased by approximately 7 oC after introducing the DPSO. The TGA results under N2 and air atmospheres showed that the initial degradation temperature for 5% weight loss (Td 5%), temperature for 50% weight loss (Td 50%) and residual weight percent at 800 oC (R800) all increased after introducing DPSO. Moreover, the addition of 3 phr DPSO100 resulted in a 70.4% increase in impact strength compared to that of the neat epoxy. The morphology of the fracture surfaces shows that the miscibility of polysiloxane with epoxy resin increased with increasing number of epoxy groups in DPSO, and the improved toughness was attributed to the rubber-bridged effect. The high number of epoxy groups in dendritic polysiloxane can react during the curing process,and participate chemically in the crosslinking network. DPSO is expected to improve significantly the toughness and thermal stability of epoxy resin.

Modification of Epoxy Resin with Polyether-grafted-Polysiloxane and Epoxy-Miscible Polysiloxane Particles

Songqi Ma,WeiQu Liu,Dan Yu,ZhengFang Wang 한국고분자학회 2010 Macromolecular Research Vol.18 No.1

Polyether-grafted-polysiloxane (FPMS) and epoxy-miscible polysiloxane particles (EMPP) were prepared to improve the toughness of epoxy resin. The chemical structures of the products were characterized by FTIR,1H NMR, 29Si NMR, and gel permeation chromatography (GPC). The morphology of the EMPP was analyzed by transmission electron microscopy (TEM). The thermal and mechanical properties and morphologies of the polysiloxanes modified epoxy networks were examined by differential scanning calorimetry (DSC), tensile and impact testing, and scanning electron microscopy (SEM). Microspheres were observed in the EMPP modified epoxy network,whereas irregular particles were obtained for the FPMS modified epoxy resin. The FPMS and EMPP effectively improved the tensile and impact strength of the cured epoxies, while the glass transition temperatures (Tgs)were depressed slightly. Moreover, with the same content of modifiers, the EMPP-modified epoxy network exhibited higher impact strength and lower Tgs than the FPMS-modified epoxy network.

Hydrophobic Waterborne Epoxy Coating Modified by Low Concentrations of Fluorinated Reactive Modifier

Hongyi Shi,Weiqu Liu,Maiping Yang,Xinsheng Liu,Yankun Xie,Zhengfang Wang 한국고분자학회 2019 Macromolecular Research Vol.27 No.4

Fluorinated (meth) acrylate oligomer modified epoxy resin (PHFBMA-DGEBA) and polyether-modified epoxy resin (MPEG-DGEBA) were successfully synthesized and used as reactive modifier and emulsifier for epoxy resins, respectively. GPC, FTIR and 1H NMR were employed to verify the synthesis. The influence of both the concentration and the molecular weight of PHFBMA-DGEBA on the properties of waterborne epoxy resin coatings was investigated. Surface energy and surface composition were probed by contact angle measurements and X-ray photoelectron spectroscopy (XPS), which strongly confirmed the enrichment of fluorinate atoms on the surface. The surface energy of waterborne epoxy coating was decreased from 44.46 mN/m to 23.20 mN/m by adding just 0.09 wt% PHFBMADGEBA- 2, indicating its high effectiveness in improving the surface hydrophobicity. Moreover, the physical properties of waterborne epoxy coatings prepared with different concentration and molecular weight of fluorinated reactive modifier, such as water absorption, Shore D hardness, adhesion, thermal properties and optical transmittance, were also analyzed in detail. Taken together, the waterborne epoxy coatings prepared with low concentrations of reactive modifier are economical and have great potential in large scale industry applications.

A Non-Contact Method for Real-Time Stacked Sheets Counting with X-ray Absorption Spectra and Long Short-Term Memory Network

Zheng Fang,Bingan Yuan,Mengyi Wang,Bichao Ye,Shunren Li,Yinbin Chen,Hongjun Deng,Shucheng Feng,Kun Qian 한국펄프·종이공학회 2023 펄프.종이기술 Vol.55 No.3