A sodium sulfate （NaeSO4）/silica （SiO2） composite was prepared as a shape-stabilized solid-liquid phase change material by a sol-gel procedure using Na2SiO3 as the silica source. Na2SO4 in the composite acts as a ...A sodium sulfate （NaeSO4）/silica （SiO2） composite was prepared as a shape-stabilized solid-liquid phase change material by a sol-gel procedure using Na2SiO3 as the silica source. Na2SO4 in the composite acts as a latent heat storage substance for solid-liquid phase change, while SiO2 acts as a support material to provide structural strength and prevent leakage of melted NazSO4. The microstructure and composition of the prepared composite were characterized by the N2 adsorption, transmission electron microscope （TEM）, scanning electron microscope （SEM）, Fourier transform infrared spectroscopy （FTIR） and X-ray diffraction. The results show that the prepared Na2SOJSiO2 composite is a nanostructured hybrid of NazSO4 and SiO2 without new substances produced during the phase change. The macroscopic shape of the NazSO4/SiO2 composite after the melting and freezing cycles does not change and there is no leakage of Na2SO4. Determined by differential scanning calorimeter （DSC） analysis, the values of phase change latent heat of melting and freezing of the prepared NazSO4/SiO2 （50%, by mass） composite are 82.3 kJ.kg i and 83.7 kJ.kg-1, and temperatures of melting and freezing are 886.0 ℃ and 880.6 ℃, respectively. Furthermore, the Na2SOJSiO2 composite maintains good thermal energy storage and release ability even after 100 cycles of melting and freezing. The satisfactory thermal storage performance renders this composite a versatile tool for high-temperature thermal energy storage.展开更多
Antifouling coatings are used extensively on vessels and underwater structures. Conventional antifouling coatings contain toxic biocides and heavy metals, which may induce unwanted adverse effects such as toxicity to ...Antifouling coatings are used extensively on vessels and underwater structures. Conventional antifouling coatings contain toxic biocides and heavy metals, which may induce unwanted adverse effects such as toxicity to non-target organisms, imposex in gastropods and increased multiresistance among bacteria. Therefore,enzyme-based coatings could be a new alternative solution. A H2O2-producing bienzyme system was developed in this study. H2O2 can be produced from starch by the cooperation of α-amylase and glucose oxidase, which promotes the hydrolysis of polymeric chain and oxidizes the glucose to produce H2O2, respectively. The encapsulated bienzyme(A-G@BS) exhibits enhanced stabilities of thermal, pH, recycling and tolerance of xylene. The A-G@BScontaining coating releases H2O2 at rates exceeding a target of 36 nmol·cm-2·d-1for 90 days in a laboratory assay. The results demonstrate that the method is a promising coating technology for entrapping active enzymes,presenting an interesting avenue for enzyme-based antifouling solutions.展开更多
In this study, SCM （supplementary cementitious materials）, such as nano silica, micro silica, fly ash and bottom ash, have been evaluated for optimal level of replacement as blending material in cement and concrete....In this study, SCM （supplementary cementitious materials）, such as nano silica, micro silica, fly ash and bottom ash, have been evaluated for optimal level of replacement as blending material in cement and concrete. The physical and chemical properties of the above materials were first analyzed. This study focused on compressive strength of concrete with different mixes at different ages. In many cases, products made with fly ash, micro silica, nano silica and bottom ash perform better than products made without them. Test results obtained in this study indicate that up to 5% nano silica, 10% micro silica, 20-30% fly ash and 10% bottom ash could be advantageously blended with cement without adversely affecting the strength. However, optimum levels of these materials are 1-3% nano silica, 3-8% micro silica, 10% fly ash and 5% of bottom ash when we consider the strength of concrete. All percentages are defined by weight unless otherwise mentioned.展开更多
A novel sol-gel processing was developed to synthesize polycrystalline cerium-doped lutetium pyrosilicate （Lu2Si2O7Ce, LPS ：Ce） powders under low temperature. It was found that the addition of propylene oxide （PPO...A novel sol-gel processing was developed to synthesize polycrystalline cerium-doped lutetium pyrosilicate （Lu2Si2O7Ce, LPS ：Ce） powders under low temperature. It was found that the addition of propylene oxide （PPO） could promote the formation of Lu-O-Si bonds in precursor, which was beneficial to the formation of LPS phase. X-ray diffraction （XRD） patterns indicated that the single-phased LPS powder was well crystallized at 1050℃. Microstructure observation demonstrated that the synthetic LPS powder was composed of ellipsoidal grains with the mean size of 40 nm. The luminescent properties were characterized by photoluminescence （PL）, X-ray excited luminescence （XEL） and vacuum ultraviolet （VUV） spectroscopy at room temperature. The synthetic LPS：Ce powder emitted a broad emission spectrum centered at about 380 nm, which should be ascribed to the 5d→4f transition of Ce3＋. Decay time of the synthetic LPS：Ce powder was measured to be only 32 ns.展开更多
Methanesulfonic acid （MSA） was successfully immobilized in silica, leading to a novel and environmentally friendly solid acid catalyst SMSA. The most important feature of SMSA is that anhydrous formic acid is used t...Methanesulfonic acid （MSA） was successfully immobilized in silica, leading to a novel and environmentally friendly solid acid catalyst SMSA. The most important feature of SMSA is that anhydrous formic acid is used to hydrolysis of tetraethylorthosili- cate （TEOS）. No water was added in the whole preparation. Therefore, MSA could be anchored in silica matrix more effec- tively instead of being dissolved in water. This new organic/inorganic hybrid catalyst was characterized by powder X-ray dif- fraction （XRD）, energy dispersive spectrum （EDS）, N2 adsorption-desorption analyzer, thermogravimetric analysis （TGA-DSC） and pyridine-FTIR. The catalytic activity was tested by alkylation of olefins and aromatics. High concentration acid sites, both Lewis and Brcnsted, abundant porosity and large surface area enabled the highest activity for SMSA, among MCM-22. ZSM-5 and industrial acidity clay.展开更多
基金Supported by the National Natural Science Foundation of China(2107611)
文摘A sodium sulfate （NaeSO4）/silica （SiO2） composite was prepared as a shape-stabilized solid-liquid phase change material by a sol-gel procedure using Na2SiO3 as the silica source. Na2SO4 in the composite acts as a latent heat storage substance for solid-liquid phase change, while SiO2 acts as a support material to provide structural strength and prevent leakage of melted NazSO4. The microstructure and composition of the prepared composite were characterized by the N2 adsorption, transmission electron microscope （TEM）, scanning electron microscope （SEM）, Fourier transform infrared spectroscopy （FTIR） and X-ray diffraction. The results show that the prepared Na2SOJSiO2 composite is a nanostructured hybrid of NazSO4 and SiO2 without new substances produced during the phase change. The macroscopic shape of the NazSO4/SiO2 composite after the melting and freezing cycles does not change and there is no leakage of Na2SO4. Determined by differential scanning calorimeter （DSC） analysis, the values of phase change latent heat of melting and freezing of the prepared NazSO4/SiO2 （50%, by mass） composite are 82.3 kJ.kg i and 83.7 kJ.kg-1, and temperatures of melting and freezing are 886.0 ℃ and 880.6 ℃, respectively. Furthermore, the Na2SOJSiO2 composite maintains good thermal energy storage and release ability even after 100 cycles of melting and freezing. The satisfactory thermal storage performance renders this composite a versatile tool for high-temperature thermal energy storage.
基金Supported by the National Natural Science Foundation of China(21006020,21276060,21276062)the Application Basic Research Plan Key Basic Research Project of Hebei Province(11965150D)the Natural Science Foundation of Tianjin(13JCYBJC18500)
文摘Antifouling coatings are used extensively on vessels and underwater structures. Conventional antifouling coatings contain toxic biocides and heavy metals, which may induce unwanted adverse effects such as toxicity to non-target organisms, imposex in gastropods and increased multiresistance among bacteria. Therefore,enzyme-based coatings could be a new alternative solution. A H2O2-producing bienzyme system was developed in this study. H2O2 can be produced from starch by the cooperation of α-amylase and glucose oxidase, which promotes the hydrolysis of polymeric chain and oxidizes the glucose to produce H2O2, respectively. The encapsulated bienzyme(A-G@BS) exhibits enhanced stabilities of thermal, pH, recycling and tolerance of xylene. The A-G@BScontaining coating releases H2O2 at rates exceeding a target of 36 nmol·cm-2·d-1for 90 days in a laboratory assay. The results demonstrate that the method is a promising coating technology for entrapping active enzymes,presenting an interesting avenue for enzyme-based antifouling solutions.
文摘In this study, SCM （supplementary cementitious materials）, such as nano silica, micro silica, fly ash and bottom ash, have been evaluated for optimal level of replacement as blending material in cement and concrete. The physical and chemical properties of the above materials were first analyzed. This study focused on compressive strength of concrete with different mixes at different ages. In many cases, products made with fly ash, micro silica, nano silica and bottom ash perform better than products made without them. Test results obtained in this study indicate that up to 5% nano silica, 10% micro silica, 20-30% fly ash and 10% bottom ash could be advantageously blended with cement without adversely affecting the strength. However, optimum levels of these materials are 1-3% nano silica, 3-8% micro silica, 10% fly ash and 5% of bottom ash when we consider the strength of concrete. All percentages are defined by weight unless otherwise mentioned.
基金supported by the National Natural Science Foundation of China(Grant No.51172139)
文摘A novel sol-gel processing was developed to synthesize polycrystalline cerium-doped lutetium pyrosilicate （Lu2Si2O7Ce, LPS ：Ce） powders under low temperature. It was found that the addition of propylene oxide （PPO） could promote the formation of Lu-O-Si bonds in precursor, which was beneficial to the formation of LPS phase. X-ray diffraction （XRD） patterns indicated that the single-phased LPS powder was well crystallized at 1050℃. Microstructure observation demonstrated that the synthetic LPS powder was composed of ellipsoidal grains with the mean size of 40 nm. The luminescent properties were characterized by photoluminescence （PL）, X-ray excited luminescence （XEL） and vacuum ultraviolet （VUV） spectroscopy at room temperature. The synthetic LPS：Ce powder emitted a broad emission spectrum centered at about 380 nm, which should be ascribed to the 5d→4f transition of Ce3＋. Decay time of the synthetic LPS：Ce powder was measured to be only 32 ns.
文摘Methanesulfonic acid （MSA） was successfully immobilized in silica, leading to a novel and environmentally friendly solid acid catalyst SMSA. The most important feature of SMSA is that anhydrous formic acid is used to hydrolysis of tetraethylorthosili- cate （TEOS）. No water was added in the whole preparation. Therefore, MSA could be anchored in silica matrix more effec- tively instead of being dissolved in water. This new organic/inorganic hybrid catalyst was characterized by powder X-ray dif- fraction （XRD）, energy dispersive spectrum （EDS）, N2 adsorption-desorption analyzer, thermogravimetric analysis （TGA-DSC） and pyridine-FTIR. The catalytic activity was tested by alkylation of olefins and aromatics. High concentration acid sites, both Lewis and Brcnsted, abundant porosity and large surface area enabled the highest activity for SMSA, among MCM-22. ZSM-5 and industrial acidity clay.
