The DC electrical resistivity-temperature characteristic is an important property for insulating materials to operate at a high stress level.In order to improve the DC electrical resistivity at elevated temperature in...The DC electrical resistivity-temperature characteristic is an important property for insulating materials to operate at a high stress level.In order to improve the DC electrical resistivity at elevated temperature in a targeted way,a positive temperature coefficient(PTC)material(Ba Ti O3-based compound(BT60))was selected as the filler in this paper,whose electrical resistivity has a PTC effect when the temperature exceeds its Curie temperature.The BT60 was treated with hydrogen peroxide and(3-Aminopropyl)triethoxysilane.Epoxy composites with different loadings of BT60 fillers(0 wt%,0.5 wt%,and 2 wt%of epoxy)were prepared,denoted as EP-0,EP-0.5,and EP-2.It was shown that BT60 was able to maintain the DC breakdown strength when its loading was less than 2 wt%of epoxy.As the temperature exceeds 60°C,BT60 will compensate for the negative temperature coefficient effect of epoxy resin to some extent.The electrical resistivity of EP-2 was improved by 55%compared with that of neat epoxy at 90°C.It was found that the potential barrier at the grain boundary of BT60 and the deep traps in the interface between BT60 and the epoxy resin hinder the migration of carriers and thus increase the electrical resistivity of epoxy composite.展开更多
The assay of trace volatile low molecular weight(MW) compounds in human breath or in ambient atmosphere typically involves gas chromatography with flame ionization detection (FID). This paper introduced a direct assa...The assay of trace volatile low molecular weight(MW) compounds in human breath or in ambient atmosphere typically involves gas chromatography with flame ionization detection (FID). This paper introduced a direct assay which can overcome the difficulties of collection low concentration samples. In order to pre concentrate the trace low MW compounds, a small trapping column filled with absorbent must be used before thermal desorption of the collected samples onto chromatographic column(packed with Porapak Q) for separation. It has been proved that the characteristic of absorbent mainly influence the recoveries and the linear range of this method is from 0 05 ng to 5200 ng for pentane, methanol, ethanol and acetone.展开更多
In order to identify the potential nephrotoxic compounds in traditional Chinese medicine Lithospermum erythrorhizon,it was separated into serial fractions according to their polarities.An in vitro method was utilized ...In order to identify the potential nephrotoxic compounds in traditional Chinese medicine Lithospermum erythrorhizon,it was separated into serial fractions according to their polarities.An in vitro method was utilized to determine the nephrotoxicity of these fractions with the help of fluorescence image analysis.As a result,the primary fraction A05 and its secondary fractions C06 ＂C09 and C12 ＂C14 were found to have significant toxicity to LLC-PK1 cell line,as determined by the survive rate less than 20% after they were treated with these fractions.These potential nephrotoxic fractions were further analyzed by multistage and high resolution mass spectrometry.The main compounds in these fractions were tentatively identified to be acetylshikonin,isobutyrylshikonin,β,β＇-dimethyla-cryloylshikonin,and isovalerylshikonin,which may bring nephrotoxicity.展开更多
基金support from National Natural Science Foundation of China(No.51977186)the China Postdoctoral Science Foundation(No.2019M650029)+3 种基金the Young Elite Scientists Sponsorship Program by CAST(No.2018QNRC001)the National Key R&D Program of China(No.2017YFB0902704)the State Key Development Program of Basic Research of China(973 Program)(No.2014CB239501)the Science and Technology Project of the State Grid Corp.of China(No.52110418001Y).
文摘The DC electrical resistivity-temperature characteristic is an important property for insulating materials to operate at a high stress level.In order to improve the DC electrical resistivity at elevated temperature in a targeted way,a positive temperature coefficient(PTC)material(Ba Ti O3-based compound(BT60))was selected as the filler in this paper,whose electrical resistivity has a PTC effect when the temperature exceeds its Curie temperature.The BT60 was treated with hydrogen peroxide and(3-Aminopropyl)triethoxysilane.Epoxy composites with different loadings of BT60 fillers(0 wt%,0.5 wt%,and 2 wt%of epoxy)were prepared,denoted as EP-0,EP-0.5,and EP-2.It was shown that BT60 was able to maintain the DC breakdown strength when its loading was less than 2 wt%of epoxy.As the temperature exceeds 60°C,BT60 will compensate for the negative temperature coefficient effect of epoxy resin to some extent.The electrical resistivity of EP-2 was improved by 55%compared with that of neat epoxy at 90°C.It was found that the potential barrier at the grain boundary of BT60 and the deep traps in the interface between BT60 and the epoxy resin hinder the migration of carriers and thus increase the electrical resistivity of epoxy composite.
文摘The assay of trace volatile low molecular weight(MW) compounds in human breath or in ambient atmosphere typically involves gas chromatography with flame ionization detection (FID). This paper introduced a direct assay which can overcome the difficulties of collection low concentration samples. In order to pre concentrate the trace low MW compounds, a small trapping column filled with absorbent must be used before thermal desorption of the collected samples onto chromatographic column(packed with Porapak Q) for separation. It has been proved that the characteristic of absorbent mainly influence the recoveries and the linear range of this method is from 0 05 ng to 5200 ng for pentane, methanol, ethanol and acetone.
基金Supported by the National Key Scientific and Technological Project of China(No.2009ZX09502-012)the Research Fund for the Doctoral Program of Higher Education of China(No.20090101110126)the Zhejiang Province Science and Technology Plan Project,China(No.2008C23065)
文摘In order to identify the potential nephrotoxic compounds in traditional Chinese medicine Lithospermum erythrorhizon,it was separated into serial fractions according to their polarities.An in vitro method was utilized to determine the nephrotoxicity of these fractions with the help of fluorescence image analysis.As a result,the primary fraction A05 and its secondary fractions C06 ＂C09 and C12 ＂C14 were found to have significant toxicity to LLC-PK1 cell line,as determined by the survive rate less than 20% after they were treated with these fractions.These potential nephrotoxic fractions were further analyzed by multistage and high resolution mass spectrometry.The main compounds in these fractions were tentatively identified to be acetylshikonin,isobutyrylshikonin,β,β＇-dimethyla-cryloylshikonin,and isovalerylshikonin,which may bring nephrotoxicity.
