To obtain the refined electrodeposited nickel layer on AZ91D magnesium alloy,ultrasonic technology was applied in the processes of pre-treatment and electrodeposition.The phases of pre-treatment layer and the nickel c...To obtain the refined electrodeposited nickel layer on AZ91D magnesium alloy,ultrasonic technology was applied in the processes of pre-treatment and electrodeposition.The phases of pre-treatment layer and the nickel coating were analyzed by X-ray diffractometry(XRD)and X-ray photoelectron spectroscopy(XPS),and the microstructure was observed by scanning electron microscopy(SEM).Then,the effects of ultrasonic dispersion on the microstructure of pre-treatment layer and the grain refinement of electrodeposited nickel layer were discussed.The results showed that the pre-treatment electrodeposited Cu-Sn layer with compact microstructure could be synthesized in alkaline copper-tin liquid with ultrasonic agitation,as a result,smooth and refined nickel coating formed on AZ91D magnesium alloy.On the other hand,preferred orientation in the coating decreased because of the refined grains.展开更多
To address the dual challenges of resource utilization of mining solid waste(e.g.,coal gangue)and performance enhancement of cemented rockfill,this study systematically investigates the mechanisms of ultrasonic disper...To address the dual challenges of resource utilization of mining solid waste(e.g.,coal gangue)and performance enhancement of cemented rockfill,this study systematically investigates the mechanisms of ultrasonic dispersion time and polycarboxylate superplasti-cizer(PCE)on the properties of cellulose nanofiber(CNF)-modified cemented rockfill.A series of comparative experiments were de-signed with varying ultrasonic dispersion times(0-60 min)and PCE dosages(0.1wt%-0.4wt%).Through mechanical testing,hydration product analysis,and microstructural characterization,the study revealed the advantages of PCE in promoting CNF dispersion to enhance the engineering applicability of cemented rockfill.The results demonstrate that:(1)Ultrasonic dispersion for 30 min increases the com-pressive strength by 37.7%compared to the untreated group;however,excessive ultrasonication(60 min)induces hydrolysis of CNF,re-leasing reducing sugars that retard hydration.(2)PCE facilitates CNF dispersion,achieving a 29.1%increase in compressive strength at a dosage of 0.4wt%,while simultaneously improving hydration products and microstructural development.(3)While ultrasonic dispersion yields slightly higher strength improvements,PCE demonstrates superior cost-effectiveness and operational convenience,rendering it more viable for industrial adoption.This study provides a theoretical foundation for the nano-enhanced modification of cemented rockfill,offering new insights into the recycling of solid waste and the development of high-performance materials.展开更多
Nanoparticle-reinforced Mg matrix composites(NPMMCs)capitalize on the synergistic properties of nanoparticles and Mg matrix,resulting in enhanced mechanical attributes compared to matrix.Nonetheless,effective high-tem...Nanoparticle-reinforced Mg matrix composites(NPMMCs)capitalize on the synergistic properties of nanoparticles and Mg matrix,resulting in enhanced mechanical attributes compared to matrix.Nonetheless,effective high-temperature dispersion of nanoparticles remains challenging.This study employs a molten salt dispersant(NaCl-KCl-MgCl_(2))effectively mitigating the oxidation and combustion of TiC nanoparticles(TiC_(np)).Compared with the atmosphere,the molten salt facilitates the pre-dispersion of TiC_(np)through thermal motion at elevated temperatures,thereby reducing agglomeration between the TiC_(np).Simultaneously,the molten salt effectively wets and disrupts the oxide layer on the surface of Mg melt,facilitating the wetting of TiC_(np)by the Mg melt.The successful incorporation of 3 vol.%TiC_(np)into the Mg matrix is achieved by utilizing molten salt,and the addition of TiC_(np)increases the viscosity of mg melt.Further dispersed by ultrasonic dispersion,the unique distribution of TiC_(np)within ring-like structures was obtained which was attributed to the increase of viscosity.As a configurational distribution,the ring-like TiC_(np)distribution morphology significantly enhances the mechanical properties of composites,as evidenced by an approximate 50%increase in compressive strength(UCS).展开更多
Functional porous microspheres used for the slow release carrier of actives in cosmetics or pharmaceuticals were prepared by modified suspension polymerization of styrene （ST） with divinylbenzene （DVB） in the pres...Functional porous microspheres used for the slow release carrier of actives in cosmetics or pharmaceuticals were prepared by modified suspension polymerization of styrene （ST） with divinylbenzene （DVB） in the presence of toluene, cyclohexanol and heptane as porogenic diluents. The use of ultrasonic dispersion decreases the beads＇ size and improves the uniformity. The effects of the porogen mixture, DVB content and solvent extraction on the surface performance of the synthesized beads were studied. The microspheres were characterized by scanning electron microscopy （SEM） and BET surface area determination. It was found that a great proportion of the non-solvating porogen increases the pore diameter and the specific surface area. High DVB concentration also results in the great specific surface area and porosity. When the ratio of toluene/cyclohexanol is 1：2, DVB content is at the range of 40%-60% and methylene chloride was used as extractant, the beads with good spherical shape and pore size were obtained. The prepared porous microspheres were applied as active carriers and showed satisfactory slow release effect. Over 10h constantly sustained release was observed in vitro releasing test for hydroquinone-loaded microspheres. Great surface area promoted high concentration of released hydroquinone.展开更多
For beta-cyclodextrin (β-CD) may form complexes with metal ions during ballmilling process, it was used as a novel carbon source to synthesize LiFePO_4/C cathode composite in lithium-ion batteries via solid-state rea...For beta-cyclodextrin (β-CD) may form complexes with metal ions during ballmilling process, it was used as a novel carbon source to synthesize LiFePO_4/C cathode composite in lithium-ion batteries via solid-state reaction. This composite should has fine particle size and good electrochemical performances. The powders were characterized by XRD, SEM, TEM and galvanostatic charge-discharge. Compared with bare LiFePO_4 and LiFePO_4/C composite with glucose as carbon source by the same procedure and nearly the same content of carbon in the final cathode, the LiFePO_4/C composite with beta-cyclodextrin as carbon source shows much higher discharge specific capacity and more excellent rate performance. Ultrasonic dispersion between ballmilling and sinter process for 2 h was appropriate and useful for final LiFePO_4/C to reach higher discharge capacity. The SEI experiment was carried out to explore the effect of beta-cyclodextrin on the cathode materials, and the results indicate that coating with beta-cyclodextrin can improve the electrochemical performance of LiFePO_4 by decreasing the resistance of charge transfer (R_ ct) and improving the chemical diffusion coefficient (D_ Li).展开更多
Various enols of 2-acylmethyl-4, 4-dimethyl-2-oxazolines were prepared in moderate yields via ultrasonically catalyzed reactions of 2, 4, 4-trimethyl-2-oxazoline with arenecarboxylic esters in the presence of UDP-t-Bu...Various enols of 2-acylmethyl-4, 4-dimethyl-2-oxazolines were prepared in moderate yields via ultrasonically catalyzed reactions of 2, 4, 4-trimethyl-2-oxazoline with arenecarboxylic esters in the presence of UDP-t-BuCl-i-Pr2NH system.展开更多
文摘To obtain the refined electrodeposited nickel layer on AZ91D magnesium alloy,ultrasonic technology was applied in the processes of pre-treatment and electrodeposition.The phases of pre-treatment layer and the nickel coating were analyzed by X-ray diffractometry(XRD)and X-ray photoelectron spectroscopy(XPS),and the microstructure was observed by scanning electron microscopy(SEM).Then,the effects of ultrasonic dispersion on the microstructure of pre-treatment layer and the grain refinement of electrodeposited nickel layer were discussed.The results showed that the pre-treatment electrodeposited Cu-Sn layer with compact microstructure could be synthesized in alkaline copper-tin liquid with ultrasonic agitation,as a result,smooth and refined nickel coating formed on AZ91D magnesium alloy.On the other hand,preferred orientation in the coating decreased because of the refined grains.
基金support from the National Natural Science Foundation of China(Nos.42372328,U23B2091,52478253,and 52374147)Natural Science Foundation of Jiangsu Province,China(No.BK20240209).
文摘To address the dual challenges of resource utilization of mining solid waste(e.g.,coal gangue)and performance enhancement of cemented rockfill,this study systematically investigates the mechanisms of ultrasonic dispersion time and polycarboxylate superplasti-cizer(PCE)on the properties of cellulose nanofiber(CNF)-modified cemented rockfill.A series of comparative experiments were de-signed with varying ultrasonic dispersion times(0-60 min)and PCE dosages(0.1wt%-0.4wt%).Through mechanical testing,hydration product analysis,and microstructural characterization,the study revealed the advantages of PCE in promoting CNF dispersion to enhance the engineering applicability of cemented rockfill.The results demonstrate that:(1)Ultrasonic dispersion for 30 min increases the com-pressive strength by 37.7%compared to the untreated group;however,excessive ultrasonication(60 min)induces hydrolysis of CNF,re-leasing reducing sugars that retard hydration.(2)PCE facilitates CNF dispersion,achieving a 29.1%increase in compressive strength at a dosage of 0.4wt%,while simultaneously improving hydration products and microstructural development.(3)While ultrasonic dispersion yields slightly higher strength improvements,PCE demonstrates superior cost-effectiveness and operational convenience,rendering it more viable for industrial adoption.This study provides a theoretical foundation for the nano-enhanced modification of cemented rockfill,offering new insights into the recycling of solid waste and the development of high-performance materials.
基金funded by the National Key Research&Development Program of China(grant no 2022YFB3705705)the National Natural Science Foundation of China(grant nos.52301142,52371107,52201115)+3 种基金the Heilongjiang Provincial Postdoctoral Science Foundation(grant no LBH-11Z22167)The Fundamental Research Funds for the Central Universities(grant no HIT.OCEF.2024035)The Science and Technology Innovation Program of Hunan Province(grant no 2022RC4012)The Shanxi Provincial Science and Technology Major Special Project plan of“Taking the lead in unveiling the list”[grant nos.202201050201012].
文摘Nanoparticle-reinforced Mg matrix composites(NPMMCs)capitalize on the synergistic properties of nanoparticles and Mg matrix,resulting in enhanced mechanical attributes compared to matrix.Nonetheless,effective high-temperature dispersion of nanoparticles remains challenging.This study employs a molten salt dispersant(NaCl-KCl-MgCl_(2))effectively mitigating the oxidation and combustion of TiC nanoparticles(TiC_(np)).Compared with the atmosphere,the molten salt facilitates the pre-dispersion of TiC_(np)through thermal motion at elevated temperatures,thereby reducing agglomeration between the TiC_(np).Simultaneously,the molten salt effectively wets and disrupts the oxide layer on the surface of Mg melt,facilitating the wetting of TiC_(np)by the Mg melt.The successful incorporation of 3 vol.%TiC_(np)into the Mg matrix is achieved by utilizing molten salt,and the addition of TiC_(np)increases the viscosity of mg melt.Further dispersed by ultrasonic dispersion,the unique distribution of TiC_(np)within ring-like structures was obtained which was attributed to the increase of viscosity.As a configurational distribution,the ring-like TiC_(np)distribution morphology significantly enhances the mechanical properties of composites,as evidenced by an approximate 50%increase in compressive strength(UCS).
基金Natural Science Foundation of Guangdong Province （No.05006556）.
文摘Functional porous microspheres used for the slow release carrier of actives in cosmetics or pharmaceuticals were prepared by modified suspension polymerization of styrene （ST） with divinylbenzene （DVB） in the presence of toluene, cyclohexanol and heptane as porogenic diluents. The use of ultrasonic dispersion decreases the beads＇ size and improves the uniformity. The effects of the porogen mixture, DVB content and solvent extraction on the surface performance of the synthesized beads were studied. The microspheres were characterized by scanning electron microscopy （SEM） and BET surface area determination. It was found that a great proportion of the non-solvating porogen increases the pore diameter and the specific surface area. High DVB concentration also results in the great specific surface area and porosity. When the ratio of toluene/cyclohexanol is 1：2, DVB content is at the range of 40%-60% and methylene chloride was used as extractant, the beads with good spherical shape and pore size were obtained. The prepared porous microspheres were applied as active carriers and showed satisfactory slow release effect. Over 10h constantly sustained release was observed in vitro releasing test for hydroquinone-loaded microspheres. Great surface area promoted high concentration of released hydroquinone.
文摘For beta-cyclodextrin (β-CD) may form complexes with metal ions during ballmilling process, it was used as a novel carbon source to synthesize LiFePO_4/C cathode composite in lithium-ion batteries via solid-state reaction. This composite should has fine particle size and good electrochemical performances. The powders were characterized by XRD, SEM, TEM and galvanostatic charge-discharge. Compared with bare LiFePO_4 and LiFePO_4/C composite with glucose as carbon source by the same procedure and nearly the same content of carbon in the final cathode, the LiFePO_4/C composite with beta-cyclodextrin as carbon source shows much higher discharge specific capacity and more excellent rate performance. Ultrasonic dispersion between ballmilling and sinter process for 2 h was appropriate and useful for final LiFePO_4/C to reach higher discharge capacity. The SEI experiment was carried out to explore the effect of beta-cyclodextrin on the cathode materials, and the results indicate that coating with beta-cyclodextrin can improve the electrochemical performance of LiFePO_4 by decreasing the resistance of charge transfer (R_ ct) and improving the chemical diffusion coefficient (D_ Li).
基金Project (No.29472046) supported by the National Natural Science Foundation of China.
文摘Various enols of 2-acylmethyl-4, 4-dimethyl-2-oxazolines were prepared in moderate yields via ultrasonically catalyzed reactions of 2, 4, 4-trimethyl-2-oxazoline with arenecarboxylic esters in the presence of UDP-t-BuCl-i-Pr2NH system.
