The adsorption of two ionic surfactants CTAB（Cetyl trimethyl ammonium bromide） and SDS（Dodecyl sodium sulfate） onto two kinds of modified starches LS（phosphoryslate starch,a kind of anionic starch） and CS-8（Qua...The adsorption of two ionic surfactants CTAB（Cetyl trimethyl ammonium bromide） and SDS（Dodecyl sodium sulfate） onto two kinds of modified starches LS（phosphoryslate starch,a kind of anionic starch） and CS-8（Quaternary starch,a kind of cationic starch） were studied by means of micro-electrophoretic method.The results show that both ionic surfactants CTAB and SDs may alternate the surface charge of two starches LS and CS-8 respectively at low concentrations,and result in the change of the isoelectric point（I.E.P）,which is drifted from pH 3.3 to pH 8.7 for LS and from pH 3.7 to pH 2.4 for CS-8.The zero potential concentration（Z.P.C） of CTAB and SDS are 8×10-6 and 7×10-5mol·dm-3,respectively.These results indicate that there are a special adsorption interaction between LS and CTAB or CS-8 and SDS.The special sorption free energy（ΔGs） was calculated according to the Guy-Chapman-Stern’s electronic double layer model,which was-37.3 KJ·mol-1 for SDS and-44.2 KJ·mol-1 for CTAB.Meanwhile,the influence of these two surfactants on LS or CS-8 pasty’s viscosity was also discussed.展开更多
集成青海东部考古数据和DEM,利用面积和墓葬相结合的估算法计算了区域史前人口数量,并利用GIS工具重建史前区域耕地面积的时空格局。结果表明：新石器马家窑文化时期区域人口、耕地迅速增加,并在晚期马厂时期达到新石器的顶峰,人口总数...集成青海东部考古数据和DEM,利用面积和墓葬相结合的估算法计算了区域史前人口数量,并利用GIS工具重建史前区域耕地面积的时空格局。结果表明：新石器马家窑文化时期区域人口、耕地迅速增加,并在晚期马厂时期达到新石器的顶峰,人口总数接近4万人,耕地面积达到462 km2,人口和耕地主要分布在黄河—湟水谷地内;齐家时期人口和耕地有一定幅度下降,在青铜时代人口和耕地有显著回升和增长,人口总数达61 000余人,耕地面积达到1 076 km2,约占区域适宜耕地总数的1/10。伴随人口与耕地的变化,人类活动的环境效应也逐步显现,5~4 ka B.P.人类活动导致研究区河谷地带乔木的减少,伴人植物增加,尤其是禾本科含量有较大幅度增加,与当时的粟作农业关系密切;4 ka B.P.后大范围的乔木减少是气候变化结果,其后人类活动加强,加速了乔木覆被面积的萎缩。展开更多
文摘The adsorption of two ionic surfactants CTAB（Cetyl trimethyl ammonium bromide） and SDS（Dodecyl sodium sulfate） onto two kinds of modified starches LS（phosphoryslate starch,a kind of anionic starch） and CS-8（Quaternary starch,a kind of cationic starch） were studied by means of micro-electrophoretic method.The results show that both ionic surfactants CTAB and SDs may alternate the surface charge of two starches LS and CS-8 respectively at low concentrations,and result in the change of the isoelectric point（I.E.P）,which is drifted from pH 3.3 to pH 8.7 for LS and from pH 3.7 to pH 2.4 for CS-8.The zero potential concentration（Z.P.C） of CTAB and SDS are 8×10-6 and 7×10-5mol·dm-3,respectively.These results indicate that there are a special adsorption interaction between LS and CTAB or CS-8 and SDS.The special sorption free energy（ΔGs） was calculated according to the Guy-Chapman-Stern’s electronic double layer model,which was-37.3 KJ·mol-1 for SDS and-44.2 KJ·mol-1 for CTAB.Meanwhile,the influence of these two surfactants on LS or CS-8 pasty’s viscosity was also discussed.
文摘集成青海东部考古数据和DEM,利用面积和墓葬相结合的估算法计算了区域史前人口数量,并利用GIS工具重建史前区域耕地面积的时空格局。结果表明：新石器马家窑文化时期区域人口、耕地迅速增加,并在晚期马厂时期达到新石器的顶峰,人口总数接近4万人,耕地面积达到462 km2,人口和耕地主要分布在黄河—湟水谷地内;齐家时期人口和耕地有一定幅度下降,在青铜时代人口和耕地有显著回升和增长,人口总数达61 000余人,耕地面积达到1 076 km2,约占区域适宜耕地总数的1/10。伴随人口与耕地的变化,人类活动的环境效应也逐步显现,5~4 ka B.P.人类活动导致研究区河谷地带乔木的减少,伴人植物增加,尤其是禾本科含量有较大幅度增加,与当时的粟作农业关系密切;4 ka B.P.后大范围的乔木减少是气候变化结果,其后人类活动加强,加速了乔木覆被面积的萎缩。
