Association of silica with diseases like cancers has been determined previously. This study was designed to determine the quantity of silis in flour produced in Golestan Province, and its relation to esophageal cancer...Association of silica with diseases like cancers has been determined previously. This study was designed to determine the quantity of silis in flour produced in Golestan Province, and its relation to esophageal cancer (EC). We took flour samples from all flour millings in Golestan Province. Base-melting method in nickel cruise was used at 550℃. The extract was reduced with acids. Different silis concentrations in various regions were compared. P < 0.05 was considered statistically significant. The median silis concentration was 0.0030 g, the mean silis concentration was 0.008760 ± 0.004265 g in each 100 g flour. The difference of mean silis concentrations in various regions was not significant. No high level of silica was found in the flour of Golestan Province. We could not find any significant difference in various areas between silica contaminations. Studies on the consumed bread and rice in various regions of Golestan Province can be helpful.展开更多
Silyl celluloses (SiC) were prepared by reacting cellulose with chloropropyltrichlorosilane (CPTCSi) and chloropropyltriethoxysilane (CPTESi) in LiCl/N,N-dimethylacetamide (DMAc). The Si content in the silyl cellulose...Silyl celluloses (SiC) were prepared by reacting cellulose with chloropropyltrichlorosilane (CPTCSi) and chloropropyltriethoxysilane (CPTESi) in LiCl/N,N-dimethylacetamide (DMAc). The Si content in the silyl cellulose could be controlled by adjustment of the molar ratio of silane and cellulose. FT-IR spectra showed that cellulose was readily reacted with the above two silane reagents, and the reactivity of CPTCSi is higher than that of CPTESi. It was presumed that the reaction process belongs to graft-polymerization. The results of differential thermal analysis (DTA) indicated that the thermostability of the materials produced increased with the increase of Si content in the sample. The acid resistance of the samples SiC in 1 mol/L HCl aqueous solution was improved significantly. When Si content was ca. 20%, the silyl cellulose has excellent thermostability, hydrophobicity, low density and stability in 1 mol/L HCl aqueous solution, owing to crosslinking of cellulose chain with silane.展开更多
Theoretical calculations of the [2,3]-sila-wittig rearrangement of isomers of [（allyloxy）silyl]lithium （C3H5O）HzSiLi have been performed in the gas phase and THF solvent using the G3MP2B3 method. Seven isomers of ...Theoretical calculations of the [2,3]-sila-wittig rearrangement of isomers of [（allyloxy）silyl]lithium （C3H5O）HzSiLi have been performed in the gas phase and THF solvent using the G3MP2B3 method. Seven isomers of silylenoid （C3H5O）H2SiLi, 1-7, are found. The [2,3]-silawittig rearrangement paths are followed using two isomers, 2 and 4, to yield the transition states as well as the products. In the transition state, the silicon center functions as a nucleophile and the aUyl as an electrophile. The interaction between the silicon and allylic sites leads to the formation of SiC（3） bond and the break of O-C（1） bond. Finally, the （allylsilyl）oxylithium （C3H5）H2SiOLi is obtained. The rearrangement paths are confirmed by the intrinsic reaction coordinate （IRC） calculations. The rearrangement mechanisms of reactions of 2 and 4 are similar, and the latter reaction is more favored in the gas phase and THF solvent. Also, the solvent effects are analyzed in this work.展开更多
This paper is devoted to studying the dynamics of a susceptible-infective-latent-infective (SILI) epidemic model that is subject to the combined effects of environmental noise and intervention strategy. We extend the ...This paper is devoted to studying the dynamics of a susceptible-infective-latent-infective (SILI) epidemic model that is subject to the combined effects of environmental noise and intervention strategy. We extend the classical SILI epidemic model from a deterministic framework to a stochastic one. For the deterministic case, the global stability analysis of the solution is carried out in terms of the basic reproduction number. For the stochastic case, sufficient conditions for the extinction of diseases are obtained. Then, the existence of stationary distribution and asymptotic behavior of the solution are further studied to illustrate the cycling phenomena of recurrent diseases. Numerical simulations are conducted to verify these analytical results. It is shown that both stochastic noise and intervention strategy contribute to the control of diseases.展开更多
On July 1 st,Qingdao Dongyue Rhodia Chemicals Co.,Ltd.commenced production of the first phase 110 000 t/a sodium silicate project in Chengyang Advanced Materials Industry Park of Qingdao,Shandongprovince.The company i...On July 1 st,Qingdao Dongyue Rhodia Chemicals Co.,Ltd.commenced production of the first phase 110 000 t/a sodium silicate project in Chengyang Advanced Materials Industry Park of Qingdao,Shandongprovince.The company is jointly setup by Qingdao Hiwin Group Ltd.,展开更多
文摘Association of silica with diseases like cancers has been determined previously. This study was designed to determine the quantity of silis in flour produced in Golestan Province, and its relation to esophageal cancer (EC). We took flour samples from all flour millings in Golestan Province. Base-melting method in nickel cruise was used at 550℃. The extract was reduced with acids. Different silis concentrations in various regions were compared. P < 0.05 was considered statistically significant. The median silis concentration was 0.0030 g, the mean silis concentration was 0.008760 ± 0.004265 g in each 100 g flour. The difference of mean silis concentrations in various regions was not significant. No high level of silica was found in the flour of Golestan Province. We could not find any significant difference in various areas between silica contaminations. Studies on the consumed bread and rice in various regions of Golestan Province can be helpful.
基金This work was supported by the National Natural Science Foundation of China (59773026 and 59933070).
文摘Silyl celluloses (SiC) were prepared by reacting cellulose with chloropropyltrichlorosilane (CPTCSi) and chloropropyltriethoxysilane (CPTESi) in LiCl/N,N-dimethylacetamide (DMAc). The Si content in the silyl cellulose could be controlled by adjustment of the molar ratio of silane and cellulose. FT-IR spectra showed that cellulose was readily reacted with the above two silane reagents, and the reactivity of CPTCSi is higher than that of CPTESi. It was presumed that the reaction process belongs to graft-polymerization. The results of differential thermal analysis (DTA) indicated that the thermostability of the materials produced increased with the increase of Si content in the sample. The acid resistance of the samples SiC in 1 mol/L HCl aqueous solution was improved significantly. When Si content was ca. 20%, the silyl cellulose has excellent thermostability, hydrophobicity, low density and stability in 1 mol/L HCl aqueous solution, owing to crosslinking of cellulose chain with silane.
基金PhD Special Research Foundation of Chinese Education Department (No. 20040422010)the Scientific Research Foundation of Yangzhou University
文摘Theoretical calculations of the [2,3]-sila-wittig rearrangement of isomers of [（allyloxy）silyl]lithium （C3H5O）HzSiLi have been performed in the gas phase and THF solvent using the G3MP2B3 method. Seven isomers of silylenoid （C3H5O）H2SiLi, 1-7, are found. The [2,3]-silawittig rearrangement paths are followed using two isomers, 2 and 4, to yield the transition states as well as the products. In the transition state, the silicon center functions as a nucleophile and the aUyl as an electrophile. The interaction between the silicon and allylic sites leads to the formation of SiC（3） bond and the break of O-C（1） bond. Finally, the （allylsilyl）oxylithium （C3H5）H2SiOLi is obtained. The rearrangement paths are confirmed by the intrinsic reaction coordinate （IRC） calculations. The rearrangement mechanisms of reactions of 2 and 4 are similar, and the latter reaction is more favored in the gas phase and THF solvent. Also, the solvent effects are analyzed in this work.
文摘This paper is devoted to studying the dynamics of a susceptible-infective-latent-infective (SILI) epidemic model that is subject to the combined effects of environmental noise and intervention strategy. We extend the classical SILI epidemic model from a deterministic framework to a stochastic one. For the deterministic case, the global stability analysis of the solution is carried out in terms of the basic reproduction number. For the stochastic case, sufficient conditions for the extinction of diseases are obtained. Then, the existence of stationary distribution and asymptotic behavior of the solution are further studied to illustrate the cycling phenomena of recurrent diseases. Numerical simulations are conducted to verify these analytical results. It is shown that both stochastic noise and intervention strategy contribute to the control of diseases.
文摘On July 1 st,Qingdao Dongyue Rhodia Chemicals Co.,Ltd.commenced production of the first phase 110 000 t/a sodium silicate project in Chengyang Advanced Materials Industry Park of Qingdao,Shandongprovince.The company is jointly setup by Qingdao Hiwin Group Ltd.,
