Chitosan starch blend films were prepared, and their structure and properties were studied by FT IR, X ray diffraction, SEM and measurement of tensile strength. IR spectra and SEM analysis showed that the two polys...Chitosan starch blend films were prepared, and their structure and properties were studied by FT IR, X ray diffraction, SEM and measurement of tensile strength. IR spectra and SEM analysis showed that the two polysaccharides were compatible, when the starch was less than 30% by weight. From X ray diffraction patterns of blend fllms,it was observed that crystallization of starch was inhibited, and recrystallization of chitosan was also affected by starch. Crystal form Ⅰ, one of the main two crystal forms of chitosan,drastically increased in 30% starch content films. These results indicated that the interactions between chitosan and starch molecules exist in the blend films. The tensile strength of the film were improved when chitosan and starch were blended by weight ratios of 8∶2 and 7∶3, in which the highest tensile strength (781 kg/cm 2) was achieved.展开更多
The molar reation enthalpy,the Michaelis constant and the observed rate constant of the reaction between the Rhus vernicifera laccase and p-phenylenediamine have been determined at 298. 15 K by LKB-2107 microcalorimet...The molar reation enthalpy,the Michaelis constant and the observed rate constant of the reaction between the Rhus vernicifera laccase and p-phenylenediamine have been determined at 298. 15 K by LKB-2107 microcalorimetry system in 0.1 mol/L phosphate salt buffer (pH7. 4) to be △rHm=-136.36±0. 36kJ/mol, Km= 5. 58×10-3 mol/L and k1 =8. 63×10-3s-1, respectively. The catalyst activity of laccase withp-phenylenediamine as substrate has been determined to be EA=0. 045 IU in the experimental condition.The observed activation energy of non-enzymic step of the reaction, the Gibbs binding energy of the combination process of laccase and substrate have been also calculated. The physical significance of the determined parameters were discussed for different step of the reaction.展开更多
The scaling off is among the most pervasive and severe deterioration types.The scaling off developed on earthen sites in Northwest China has a special and complex binary structure composed of crusted and loose layers....The scaling off is among the most pervasive and severe deterioration types.The scaling off developed on earthen sites in Northwest China has a special and complex binary structure composed of crusted and loose layers.Under the synergistic functions of external environmental elements such as rainfall,temperature,and wind,and rammed earth properties,this deterioration has gradually created the crust on the site’s surface,and has then evolved into exfoliation and finally fallen off,leading to the reciprocating progressive destruction of earthen sites.Therefore,determining the development mechanism of scaling off and implementing targeted protection measures for the scientific conservation of earthen sites has become essential.In this review study,the properties of the building material causing the binary structure and the coupling effects of water,temperature,salt,and wind on the development of scaling off were determined,and the quantitative evaluation system for this deterioration development was elaborated.After interpreting the reasons for the development of the scaling off,protective measures including chemical grouting,electro-osmosis grouting,and overlay applications were stated.This study also pointed out the research hotspots and shortage in the study process on the scaling off.The hotspots generally focused on the development mechanism of binary structure,quantitative assessment of the degree of development,and related scientific consolidation measures.The shortcomings around the above directions include less attention to the development characteristics and mechanism of scaling off on earthen sites under special environment types,optimization and applicability of quantitative evaluation models,and the development and feasibility of reinforcement slurries and methods.This study can be beneficial in providing theoretical support for the scientific conservation and engineering practice of the scaling off on the earthen sites.展开更多
文摘Chitosan starch blend films were prepared, and their structure and properties were studied by FT IR, X ray diffraction, SEM and measurement of tensile strength. IR spectra and SEM analysis showed that the two polysaccharides were compatible, when the starch was less than 30% by weight. From X ray diffraction patterns of blend fllms,it was observed that crystallization of starch was inhibited, and recrystallization of chitosan was also affected by starch. Crystal form Ⅰ, one of the main two crystal forms of chitosan,drastically increased in 30% starch content films. These results indicated that the interactions between chitosan and starch molecules exist in the blend films. The tensile strength of the film were improved when chitosan and starch were blended by weight ratios of 8∶2 and 7∶3, in which the highest tensile strength (781 kg/cm 2) was achieved.
文摘The molar reation enthalpy,the Michaelis constant and the observed rate constant of the reaction between the Rhus vernicifera laccase and p-phenylenediamine have been determined at 298. 15 K by LKB-2107 microcalorimetry system in 0.1 mol/L phosphate salt buffer (pH7. 4) to be △rHm=-136.36±0. 36kJ/mol, Km= 5. 58×10-3 mol/L and k1 =8. 63×10-3s-1, respectively. The catalyst activity of laccase withp-phenylenediamine as substrate has been determined to be EA=0. 045 IU in the experimental condition.The observed activation energy of non-enzymic step of the reaction, the Gibbs binding energy of the combination process of laccase and substrate have been also calculated. The physical significance of the determined parameters were discussed for different step of the reaction.
基金supported by the National Natural Science Foundation of China(Grant Nos.42202313 and 41562015)the National Key R&D Program of China(Grant No.2020YFC1521904)+2 种基金the Social Science Fund of Shaanxi Province of China(Grant No.2021G014)the Key Projects of Two Chain Integration of Shaanxi Province of China(Protection and Utilization of Cultural Heritage)(Grant No.2022LL-ZD-01)the High-level Humanities and Social Science Outstanding Achievement Award Cultivation Project of Northwestern Polytechnical University(Grant No.G2022KY0603)。
文摘The scaling off is among the most pervasive and severe deterioration types.The scaling off developed on earthen sites in Northwest China has a special and complex binary structure composed of crusted and loose layers.Under the synergistic functions of external environmental elements such as rainfall,temperature,and wind,and rammed earth properties,this deterioration has gradually created the crust on the site’s surface,and has then evolved into exfoliation and finally fallen off,leading to the reciprocating progressive destruction of earthen sites.Therefore,determining the development mechanism of scaling off and implementing targeted protection measures for the scientific conservation of earthen sites has become essential.In this review study,the properties of the building material causing the binary structure and the coupling effects of water,temperature,salt,and wind on the development of scaling off were determined,and the quantitative evaluation system for this deterioration development was elaborated.After interpreting the reasons for the development of the scaling off,protective measures including chemical grouting,electro-osmosis grouting,and overlay applications were stated.This study also pointed out the research hotspots and shortage in the study process on the scaling off.The hotspots generally focused on the development mechanism of binary structure,quantitative assessment of the degree of development,and related scientific consolidation measures.The shortcomings around the above directions include less attention to the development characteristics and mechanism of scaling off on earthen sites under special environment types,optimization and applicability of quantitative evaluation models,and the development and feasibility of reinforcement slurries and methods.This study can be beneficial in providing theoretical support for the scientific conservation and engineering practice of the scaling off on the earthen sites.
