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  • Author or Editor: Z. Chaocan x
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Abstract  

Three samples of silicon dioxide were syhthesized and their surface areas were measured. A thermo-chemical cycle was designed to calculate the molar formation enthalpy. The molar formation enthalpy, Δf H m Φ, for three amorphous silica with the Langmuir surface area 198.0854, 25.1108 and 11.9821 m2 g−1 gave −895.52, −910.86 and −915.67 kJ mol−1, respectively. With the increasing surface area, the values of Δf H m Φ increased accordingly. The results suggest that the silica with larger surface area is more unstable. The wetting heat was also measured by adding the silica powder into water. With the rehydration of the more SiOH groups on the surface, the larger surface areas of silica lead to the more wetting heat. A smaller particle has the more unstable hydroxyl groups and surface energy.

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Abstract  

The standard molar enthalpy of combustion of cholesterol was measured at constant volume. According to value of Δr U m θ(−14358.4±20.65 kJ mol−1), Δr H m θ(−14385.7 kJ mol−1) of combustion reaction and Δf H m θ(2812.9 kJ mol−1) of cholesterol were obtained from the reaction equation. The enthalpy of combustion reaction of cholesterol was also estimated by the average bond enthalpies. By design of a thermo-chemical recycle, the enthalpy of combustion of cholesterol were calculated between 283.15∼373.15 K. Besides, molar enthalpy and entropy of fusion of cholesterol was obtained by DSC technique.

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Abstract  

The biological activity of a kind of hetero-bimetallic Schiff-base complex was studied using Escherichia coli (E. coli) cell as the target. By microcalorimetry, the difference of anti-bacterial activity between the binuclear Schiff-base and the ligand was determined and analyzed. To analyze the inhibition of the bacterial growth internally, the E. coli cells grown in the presence of hetero-bimetallic Schiff-base complex were observed by scanning electron microscopy. The images in high resolution revealed the damage of outer cell membrane caused the inhibitory effect on E. coli. Inductively coupled plasma-mass spectrometry results proved the absorption of the complex by cells, which confirmed the interaction between the Schiff-base and biological macromolecule.

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