The challenge of high temperatures in deep mining remains harmful to the health of workers and their production efficiency The addition of phase change materials (PCMs) to filling slurry and the use of the cold storag...The challenge of high temperatures in deep mining remains harmful to the health of workers and their production efficiency The addition of phase change materials (PCMs) to filling slurry and the use of the cold storage function of these materials to reduce downhole temperatures is an effective approach to alleviate the aforementioned problem.Paraffin–CaCl_(2)·6H_(2)O composite PCM was prepared in the laboratory.The composition,phase change latent heat,thermal conductivity,and cemented tailing backfill (CTB) compressive strength of the new material were studied.The heat transfer characteristics and endothermic effect of the PCM were simulated using Fluent software.The results showed the following:(1) The new paraffin–CaCl_(2)·6H_(2)O composite PCM improved the thermal conductivity of native paraffin while avoiding the water solubility of CaCl_(2)·6H_(2)O.(2) The calculation formula of the thermal conductivity of CaCl_(2)·6H_(2)O combined with paraffin was deduced,and the reasons were explained in principle.(3) The“enthalpy–mass scale model”was applied to calculate the phase change latent heat of nonreactive composite PCMs.(4)The addition of the paraffin–CaCl_(2)·6H_(2)O composite PCM reduced the CTB strength but increased its heat absorption capacity.This research can give a theoretical foundation for the use of heat storage backfill in green mines.展开更多
Thermal interface materials(TIMs) play a vital role in the thermal management of electronic devices and can significantly reduce thermal contact resistance(TCR). The TCR between the solid–liquid contact surface is mu...Thermal interface materials(TIMs) play a vital role in the thermal management of electronic devices and can significantly reduce thermal contact resistance(TCR). The TCR between the solid–liquid contact surface is much smaller than that of the solid–solid contact surface, but conventional solid–liquid phase change materials are likely to cause serious leakage. Therefore, this work has prepared a new formstable phase change thermal interface material. Through the melt blending of paraffin wax(PW) and low-density polyethylene(LDPE), the stability is improved and it has an excellent coating effect on PW. The addition of aluminum(Al) powder improves the low thermal conductivity of PW/LDPE, and the addition of 15wt% Al powder improves the thermal conductivity of the internal structure of the matrix by 67%. In addition, the influence of the addition of Al powder on the internal structure, thermal properties, and phase change behavior of the PW/LDPE matrix was systematically studied. The results confirmed that the addition of Al powder improved the thermal conductivity of the material without a significant impact on other properties, and the thermal conductivity increased with the increase of Al addition. Therefore, morphologically stable PW/LDPE/Al is an important development direction for TIMs.展开更多
Nano-emulsion,a kinetically stable system of nanosized oil droplets in water has been numerously used as a medium for biological and medicinal processes.It is also used as a solubilizing medium for compounds or molecu...Nano-emulsion,a kinetically stable system of nanosized oil droplets in water has been numerously used as a medium for biological and medicinal processes.It is also used as a solubilizing medium for compounds or molecules that are insoluble or poorly soluble in aqueous medium in addition to its use as a penetration enhancer in dermatological processes.Ferrocene,a metallocene that is known to be quite insoluble in aqueous medium is liberally soluble in the prepared oil-in-water nano-emulsion.In this medium,ferrocene undergoes a quasi-reversible reaction process and its relevant electrochemical kinetic parameters such as the heterogeneous rate constant,ko,the formal redox potential,Eo,the half-wave potential,E1/2,the electron transfer coefficient,α,and its diffusion coefficient,D,are determined in this medium.These important electrochemical parameters including the observed current function have been used to formulate a plausible mechanism for the oxidation of ferrocene in the formulated nano-emulsion.展开更多
The current research aimed to optimize the preparation technology of tributyrin nano-emulsion(TBNE)to improve its digestion properties, which were investigated through digestion models in vitro and in vivo. The conten...The current research aimed to optimize the preparation technology of tributyrin nano-emulsion(TBNE)to improve its digestion properties, which were investigated through digestion models in vitro and in vivo. The content of each component of TBNE was optimized by response surface methodology(RSM) to improve the z-average particle size and stability of TBNE. The optimized TBNE was evaluated for its digestion properties by in vitro and in vivo models. The preparation conditions of TBNE optimized by RSM were as follows: 61.3% of sorbitol, 32.7% of tributyrin, and 6.0% of modified phospholipid(MP). The predicted z-average particle size of TBNE was(246.02 ± 18.10) nm. The results of the verification test showed that the z-average particle size, zeta potential, conductivity, emulsification activity index, and emulsification stability index of TBNE were(250.02 ± 7.18) nm,(-40.23 ± 0.76) m V,(31.80 ± 2.09) μS/cm,(848.00 ± 84.53) min and(1.14 ± 0.02) m^(2)/g, respectively. The in vitro digestion experiment results showed that the TBNE remained stable in the stomach and was released in the intestine, while the size of TBNE in the gastrointestinal tact was significantly smaller than that of tributyrin(P < 0.05), which made it easier to be digested and absorbed. Compared with tributyrin treatment, TBNE significantly promoted the average body weight at the 7th day, average daily feed intake,average daily gain, feed/gain, ileum weight, and organ index of ileum of Hy-Line BROWN chicks(P < 0.05), and the butyric acid content in the ileal chyme from TBNE and tributyrin treatment were172.18 mg/m L and 100.85 mg/m L(P < 0.01). Therefore, the established TBNE technology in this study could be supposed to improve the digestion properties of tributyrin.展开更多
基金financial support provided by the National Natural Science Foundation of China (No. 52174106)the Key Technology Research and Development Program (No. 2022YFC2905102)。
文摘The challenge of high temperatures in deep mining remains harmful to the health of workers and their production efficiency The addition of phase change materials (PCMs) to filling slurry and the use of the cold storage function of these materials to reduce downhole temperatures is an effective approach to alleviate the aforementioned problem.Paraffin–CaCl_(2)·6H_(2)O composite PCM was prepared in the laboratory.The composition,phase change latent heat,thermal conductivity,and cemented tailing backfill (CTB) compressive strength of the new material were studied.The heat transfer characteristics and endothermic effect of the PCM were simulated using Fluent software.The results showed the following:(1) The new paraffin–CaCl_(2)·6H_(2)O composite PCM improved the thermal conductivity of native paraffin while avoiding the water solubility of CaCl_(2)·6H_(2)O.(2) The calculation formula of the thermal conductivity of CaCl_(2)·6H_(2)O combined with paraffin was deduced,and the reasons were explained in principle.(3) The“enthalpy–mass scale model”was applied to calculate the phase change latent heat of nonreactive composite PCMs.(4)The addition of the paraffin–CaCl_(2)·6H_(2)O composite PCM reduced the CTB strength but increased its heat absorption capacity.This research can give a theoretical foundation for the use of heat storage backfill in green mines.
基金supported by the National Natural Science Foundation of China, China (No. 51874047)the Key Science and Technology Project of Changsha City, China (No. kq2102005)+1 种基金the Special Fund for the Construction of Innovative Province in Hunan Province, China (No. 2020RC3038)the Changsha City Fund for Distinguished and Innovative Young Scholars, China (No. kq1802007)。
文摘Thermal interface materials(TIMs) play a vital role in the thermal management of electronic devices and can significantly reduce thermal contact resistance(TCR). The TCR between the solid–liquid contact surface is much smaller than that of the solid–solid contact surface, but conventional solid–liquid phase change materials are likely to cause serious leakage. Therefore, this work has prepared a new formstable phase change thermal interface material. Through the melt blending of paraffin wax(PW) and low-density polyethylene(LDPE), the stability is improved and it has an excellent coating effect on PW. The addition of aluminum(Al) powder improves the low thermal conductivity of PW/LDPE, and the addition of 15wt% Al powder improves the thermal conductivity of the internal structure of the matrix by 67%. In addition, the influence of the addition of Al powder on the internal structure, thermal properties, and phase change behavior of the PW/LDPE matrix was systematically studied. The results confirmed that the addition of Al powder improved the thermal conductivity of the material without a significant impact on other properties, and the thermal conductivity increased with the increase of Al addition. Therefore, morphologically stable PW/LDPE/Al is an important development direction for TIMs.
基金The author is grateful to the Department of Chemistry of Morgan State University for its support of this work.
文摘Nano-emulsion,a kinetically stable system of nanosized oil droplets in water has been numerously used as a medium for biological and medicinal processes.It is also used as a solubilizing medium for compounds or molecules that are insoluble or poorly soluble in aqueous medium in addition to its use as a penetration enhancer in dermatological processes.Ferrocene,a metallocene that is known to be quite insoluble in aqueous medium is liberally soluble in the prepared oil-in-water nano-emulsion.In this medium,ferrocene undergoes a quasi-reversible reaction process and its relevant electrochemical kinetic parameters such as the heterogeneous rate constant,ko,the formal redox potential,Eo,the half-wave potential,E1/2,the electron transfer coefficient,α,and its diffusion coefficient,D,are determined in this medium.These important electrochemical parameters including the observed current function have been used to formulate a plausible mechanism for the oxidation of ferrocene in the formulated nano-emulsion.
基金financially supported by the National Key Research and Development Program of China(2021YFD1300300)the National Natural Science Foundation of China(31371782)the Foundation of Henan University of Technology(2020BS008)。
文摘The current research aimed to optimize the preparation technology of tributyrin nano-emulsion(TBNE)to improve its digestion properties, which were investigated through digestion models in vitro and in vivo. The content of each component of TBNE was optimized by response surface methodology(RSM) to improve the z-average particle size and stability of TBNE. The optimized TBNE was evaluated for its digestion properties by in vitro and in vivo models. The preparation conditions of TBNE optimized by RSM were as follows: 61.3% of sorbitol, 32.7% of tributyrin, and 6.0% of modified phospholipid(MP). The predicted z-average particle size of TBNE was(246.02 ± 18.10) nm. The results of the verification test showed that the z-average particle size, zeta potential, conductivity, emulsification activity index, and emulsification stability index of TBNE were(250.02 ± 7.18) nm,(-40.23 ± 0.76) m V,(31.80 ± 2.09) μS/cm,(848.00 ± 84.53) min and(1.14 ± 0.02) m^(2)/g, respectively. The in vitro digestion experiment results showed that the TBNE remained stable in the stomach and was released in the intestine, while the size of TBNE in the gastrointestinal tact was significantly smaller than that of tributyrin(P < 0.05), which made it easier to be digested and absorbed. Compared with tributyrin treatment, TBNE significantly promoted the average body weight at the 7th day, average daily feed intake,average daily gain, feed/gain, ileum weight, and organ index of ileum of Hy-Line BROWN chicks(P < 0.05), and the butyric acid content in the ileal chyme from TBNE and tributyrin treatment were172.18 mg/m L and 100.85 mg/m L(P < 0.01). Therefore, the established TBNE technology in this study could be supposed to improve the digestion properties of tributyrin.
