The polymorphism of D-Mannitol(mannitol) is reviewed in this paper. It was found that the structure of the stable form is consistent in most literatures, but different authors have given different information about th...The polymorphism of D-Mannitol(mannitol) is reviewed in this paper. It was found that the structure of the stable form is consistent in most literatures, but different authors have given different information about the two metastable forms. Therefore the commonly used nomenclature of mannitol was summarized based on the crystal unit cell parameters with the help of X-ray powder diffraction. Moreover, the crystal growth mechanism of mannitol polymorphs was summarized. Considering the lack of kinetic data for the metastable form especially, a reported method was attempted to apply to δ mannitol in an aqueous cooling crystallization process based on the induction time previously measured, and it was identified that the growth of the δ form follows the two-dimensional(2D) nucleationmediated mechanism. The results also indicate that the method based on induction time and supersaturation should have the potential to be expanded to the metastable polymorphs for the growth property study in a bulk system.展开更多
It has been a long-standing puzzling problem that some glasses exhibit higher glass transition temperatures(denoting high stability)but lower activation energy for relaxations(denoting low stability).In this paper,the...It has been a long-standing puzzling problem that some glasses exhibit higher glass transition temperatures(denoting high stability)but lower activation energy for relaxations(denoting low stability).In this paper,the relaxation kinetics of the nanoconfined D-mannitol(DM)glass was studied systematically using a high-precision and high-rate nanocalorimeter.The nanoconfined DM exhibits enhanced thermal stability compared to the free DM.For example,the critical cooling rate for glass formation decreases from 200 K/s to below 1 K/s;the Tg increases by about 20 K–50 K.The relaxation kinetics is analyzed based on the absolute reaction rate theory.It is found that,even though the activation energy E^(*)decreases,the activation entropy S^(*)decreases much more for the nanoconfined glass that yields a large activation free energy G^(*)and higher thermal stability.These results suggest that the activation entropy may provide new insights in understanding the abnormal kinetics of nanoconfined glassy systems.展开更多
A method for selective reaction of 1-aryl-propane-1-ones with 1,2-dihydrxy grop of D-mannitol in the presence of ZnCl2-BF3 Et2O to 1, 2_O-(1-aryl- propylidene )-D-mannitol (1-4 ) is described. The compounds were first...A method for selective reaction of 1-aryl-propane-1-ones with 1,2-dihydrxy grop of D-mannitol in the presence of ZnCl2-BF3 Et2O to 1, 2_O-(1-aryl- propylidene )-D-mannitol (1-4 ) is described. The compounds were first reported and determined by IR, MS, 1H-/13C-NMR spectra.among them the Shae of 1 was further defined by X-ray diffraction展开更多
The goal of this work was to measure the heat transfer rates from thermofluid, Therminol 66, to two phase change materials, D-mannitol and adipic acid. It concerns the determination of heat transfer coefficients for t...The goal of this work was to measure the heat transfer rates from thermofluid, Therminol 66, to two phase change materials, D-mannitol and adipic acid. It concerns the determination of heat transfer coefficients for the design of a concentrated solar energy plant requiring PCM thermal energy storage and is part of a wider set of experiments, where several PCMs were tested. An experimental installation was used with a cylindrical vessel with three tubes disposed almost horizontally (5°inclination), containing the phase change material, around which the thermal fluid flowed almost perpendicular to the tubes. The experimental installation allowed to recreate heating and cooling cycles. In order to evaluate the influence of the flow on the rate at which the heating and cooling processes took place, tests were performed at different thermofluid mass flow rates, concluding that there is no great influence, since the thermal resistance inside the tubes is much higher than on the outside. D-mannitol and adipic acid, present different phase change temperatures, 164°C for D-mannitol and 152°C for adipic acid. The average heat transfer coefficient, during the phase change process, was of 340 W/(m<sup>2</sup>K) for D-mannitol and 1320 W/(m<sup>2</sup>K) for adipic acid.展开更多
The relaxation kinetics and phase transformations of the confined D-mannitol(DM)in nanoporous alumina are studied in-situ using a high-precision nano-calorimeter.We find that the crystallization behavior can be suppre...The relaxation kinetics and phase transformations of the confined D-mannitol(DM)in nanoporous alumina are studied in-situ using a high-precision nano-calorimeter.We find that the crystallization behavior can be suppressed when it is confined in nanopores smaller than 50 nm.The confined DM glass has a much smaller fragility(~76)than free DM glass(~125),confirming the enhanced glass-forming ability.It is intriguing that during isothermal annealing both the confined and free DM glasses relaxation kinetics experience two relaxation stages that have distinct activation energies.The relaxation activation energy of the confined glass is about 25%-29%smaller than the free glass,which is attributed to the reduced dimensionality.The abnormal kinetics observed in the confined DM glass open a new avenue for preparing stable glasses.展开更多
以D 甘露醇为原料,先与丙酮缩合合成1,2,5,6 二 O 异亚丙基 D 甘露醇,再对剩下的3,4位上的羟基进行甲醚化,同时脱去异亚丙基保护基团,经两步反应合成了目标化合物3,4 二 O 甲基 D 甘露醇,产率约60%。抗肿瘤活性表明IC50(宫颈癌细胞样)为...以D 甘露醇为原料,先与丙酮缩合合成1,2,5,6 二 O 异亚丙基 D 甘露醇,再对剩下的3,4位上的羟基进行甲醚化,同时脱去异亚丙基保护基团,经两步反应合成了目标化合物3,4 二 O 甲基 D 甘露醇,产率约60%。抗肿瘤活性表明IC50(宫颈癌细胞样)为4 5μg/mL,IC50(口腔表皮样癌细胞样)为10μg/mL。展开更多
基金Supported by the National Natural Science Foundation of China(No.21406049)the Natural Science Foundation of Hebei Province(B2015202090)the China Postdoctoral Science Foundation(2015M581283)
文摘The polymorphism of D-Mannitol(mannitol) is reviewed in this paper. It was found that the structure of the stable form is consistent in most literatures, but different authors have given different information about the two metastable forms. Therefore the commonly used nomenclature of mannitol was summarized based on the crystal unit cell parameters with the help of X-ray powder diffraction. Moreover, the crystal growth mechanism of mannitol polymorphs was summarized. Considering the lack of kinetic data for the metastable form especially, a reported method was attempted to apply to δ mannitol in an aqueous cooling crystallization process based on the induction time previously measured, and it was identified that the growth of the δ form follows the two-dimensional(2D) nucleationmediated mechanism. The results also indicate that the method based on induction time and supersaturation should have the potential to be expanded to the metastable polymorphs for the growth property study in a bulk system.
基金the National Natural Science Foundation of China(Grant Nos.52001319,52071327,51922102,51771216,and 51701230)the Natural Science Foundation of Zhejiang Province,China(Grant Nos.LR18E010002)+1 种基金the Ningbo 2025 Science and Technology Innovation Project(Grant No.2019B10051)the Natural Science Foundation of Ningbo City(Grant No.202003N4354)。
文摘It has been a long-standing puzzling problem that some glasses exhibit higher glass transition temperatures(denoting high stability)but lower activation energy for relaxations(denoting low stability).In this paper,the relaxation kinetics of the nanoconfined D-mannitol(DM)glass was studied systematically using a high-precision and high-rate nanocalorimeter.The nanoconfined DM exhibits enhanced thermal stability compared to the free DM.For example,the critical cooling rate for glass formation decreases from 200 K/s to below 1 K/s;the Tg increases by about 20 K–50 K.The relaxation kinetics is analyzed based on the absolute reaction rate theory.It is found that,even though the activation energy E^(*)decreases,the activation entropy S^(*)decreases much more for the nanoconfined glass that yields a large activation free energy G^(*)and higher thermal stability.These results suggest that the activation entropy may provide new insights in understanding the abnormal kinetics of nanoconfined glassy systems.
文摘A method for selective reaction of 1-aryl-propane-1-ones with 1,2-dihydrxy grop of D-mannitol in the presence of ZnCl2-BF3 Et2O to 1, 2_O-(1-aryl- propylidene )-D-mannitol (1-4 ) is described. The compounds were first reported and determined by IR, MS, 1H-/13C-NMR spectra.among them the Shae of 1 was further defined by X-ray diffraction
文摘The goal of this work was to measure the heat transfer rates from thermofluid, Therminol 66, to two phase change materials, D-mannitol and adipic acid. It concerns the determination of heat transfer coefficients for the design of a concentrated solar energy plant requiring PCM thermal energy storage and is part of a wider set of experiments, where several PCMs were tested. An experimental installation was used with a cylindrical vessel with three tubes disposed almost horizontally (5°inclination), containing the phase change material, around which the thermal fluid flowed almost perpendicular to the tubes. The experimental installation allowed to recreate heating and cooling cycles. In order to evaluate the influence of the flow on the rate at which the heating and cooling processes took place, tests were performed at different thermofluid mass flow rates, concluding that there is no great influence, since the thermal resistance inside the tubes is much higher than on the outside. D-mannitol and adipic acid, present different phase change temperatures, 164°C for D-mannitol and 152°C for adipic acid. The average heat transfer coefficient, during the phase change process, was of 340 W/(m<sup>2</sup>K) for D-mannitol and 1320 W/(m<sup>2</sup>K) for adipic acid.
基金supported by the National Key R&D Program of China (Grant Nos. 2018YFA0703602, and 2018YFA0703604)the National Natural Science Foundation of China (Grant Nos. 51701230, 51922102, and 51771216)+1 种基金Zhejiang Provincial Natural Science Foundation of China (Grant No. LR18E010002)Ningbo Science and Technology Innovation 2025 Project (Grant No. 2019B10051)
文摘The relaxation kinetics and phase transformations of the confined D-mannitol(DM)in nanoporous alumina are studied in-situ using a high-precision nano-calorimeter.We find that the crystallization behavior can be suppressed when it is confined in nanopores smaller than 50 nm.The confined DM glass has a much smaller fragility(~76)than free DM glass(~125),confirming the enhanced glass-forming ability.It is intriguing that during isothermal annealing both the confined and free DM glasses relaxation kinetics experience two relaxation stages that have distinct activation energies.The relaxation activation energy of the confined glass is about 25%-29%smaller than the free glass,which is attributed to the reduced dimensionality.The abnormal kinetics observed in the confined DM glass open a new avenue for preparing stable glasses.
文摘以D 甘露醇为原料,先与丙酮缩合合成1,2,5,6 二 O 异亚丙基 D 甘露醇,再对剩下的3,4位上的羟基进行甲醚化,同时脱去异亚丙基保护基团,经两步反应合成了目标化合物3,4 二 O 甲基 D 甘露醇,产率约60%。抗肿瘤活性表明IC50(宫颈癌细胞样)为4 5μg/mL,IC50(口腔表皮样癌细胞样)为10μg/mL。
