It is necessary to modify the running-in process for the application of ceramics using water as a lubricant in real conditions because ceramics sliding in water are characterized by a running-in period with severe fri...It is necessary to modify the running-in process for the application of ceramics using water as a lubricant in real conditions because ceramics sliding in water are characterized by a running-in period with severe friction and wear.Fullerenol,a kind of highly water-soluble nanoparticle,was synthesized and then used to ameliorate the tribological properties of Si 3 N 4 sliding against Al 2 O 3 in pure water.With the addition of fullerenol,the running-in period was shortened from 30 min to 100 s at a speed of 250 mm/s.The speed threshold above which ultralow friction can be obtained in a short time was expanded from 450 mm/s to 80 mm/s.Meanwhile,the load-carrying ability of water film was increased.The role of fullerenol was discussed based on observation of the wear scar by an optical interferometer and XPS characterization of the tribo-film on the wear track.展开更多
This paper reviews our work on the fundamental principles of high gravity controlled precipitation (HGCP) technology, and its applications in the production of drug nanoparticles, which was carried out in a rotating p...This paper reviews our work on the fundamental principles of high gravity controlled precipitation (HGCP) technology, and its applications in the production of drug nanoparticles, which was carried out in a rotating packed bed (RPB). Several kinds of drug nanoparticles with narrow particle size distributions (PSDs) were successfully prepared via HGCP, including the 300-nm Cefuroxime Axetil (CFA) particles, 200–400-nm cephradine particles, 500-nm salbutamol sulfate (SS) particles (100 nm in width), and 850-nm beclomethasone dipropionate (BDP) particles, etc. Compared to drugs available in the current market, all the drug nanoparticles produced by HGCP exhibited advantages in both formulation and drug delivery, thus improving the bioavailability of drugs. HGCP is essentially a platform technology for the preparation of poorly water-soluble drug nanoparticles for oral and injection delivery, and of inhalable drugs for pulmonary delivery. Consequently, HGCP offers potential applications in the pharmaceutical industry due to its cost-effectiveness, efficient processing and the ease of scaling-up.展开更多
The creation of ultrafine alloy nanoparticles(<5 nm) that can maintain surface activity and avoid aggregation for heterogeneous catalysis has received much attention and is extremely challenging.Here,ultrafine PtRh...The creation of ultrafine alloy nanoparticles(<5 nm) that can maintain surface activity and avoid aggregation for heterogeneous catalysis has received much attention and is extremely challenging.Here,ultrafine PtRh alloy nanoparticles imprisoned by the cavities of reduced chiral covalent imine cage(PtRh@RCC3) are prepared successfully by an organic molecular cage(OMC) confinement strategy,while the soluble RCC3 can act as a homogenizer to homogenize the heterogeneous PtRh alloy in solution.Moreover,the X-ray absorption near-edge structure(XANES) results show that the RCC3 can act as an electron-acceptor to withdraw electrons from Pt,leading to the formation of higher valence Pt atoms,which is beneficial to improving the catalytic activity for the reduction of 4-nitrophenol.Attributed to the synergistic effect of Pt/Rh atoms and the unique function of the RCC3,the reaction rate constants of Pt_(1)Rh_(16)@RCC3 are 49.6,8.2,and 5.5 times than those of the Pt_(1)Rh_(16)bulk,Pt@RCC3 and Rh@RCC3,respectively.This work provides a feasible strategy to homogenize heterogeneous alloy nanoparticle catalysts in solution,showing huge potential for advanced catalytic application.展开更多
In recent years, silica nanoparticle aggregates （SNPAs） have been used to decrease the injection pressure of wells in low permeability reservoirs achieving good results. In order to study the mechanisms for reductio...In recent years, silica nanoparticle aggregates （SNPAs） have been used to decrease the injection pressure of wells in low permeability reservoirs achieving good results. In order to study the mechanisms for reduction in the injection pressure of low permeability wells by the SNPA-diesel oil system injection, the microstructure of SNPAs was observed with a transmission electron microscope （TEM）. The particle size distribution of SNPAs was also measured by the laser scattering method. The viscosities of diesel oil and SNPA-diesel oil system were measured with a capillary viscometer. The effect of SNPAs on the solubility of wax in the diesel oil was experimentally studied. The influencing factors, including temperature and SNPA concentration in diesel oil, on wax solubility were analyzed. A pore-throat film displacement model （PTFDM） was built for mechanism explanation. The microstructure and size distribution analyses show that the SNPAs are in the nanometer size range. The viscosity of the SNPA-diesel oil system is lower than that of the diesel oil. The solubility of wax in the diesel oil increases greatly due to SNPA addition, the solubility ratio reaches 7.5. The solubility of wax in diesel oil increases with increases in the concentration of SNPAs in the diesel oil and with the temperature. It is proved that the addition of SNPAs to diesel oil helps remove the wax deposited near the wellbore. This maybe one of the main mechanisms for injection pressure decreases in low permeability reservoirs.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 50805086 and 50730007)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (Grant Nos. 51021064 and 20821003)the National Basic Research Program of China (973 Program) (Grant No.2011CB302100)
文摘It is necessary to modify the running-in process for the application of ceramics using water as a lubricant in real conditions because ceramics sliding in water are characterized by a running-in period with severe friction and wear.Fullerenol,a kind of highly water-soluble nanoparticle,was synthesized and then used to ameliorate the tribological properties of Si 3 N 4 sliding against Al 2 O 3 in pure water.With the addition of fullerenol,the running-in period was shortened from 30 min to 100 s at a speed of 250 mm/s.The speed threshold above which ultralow friction can be obtained in a short time was expanded from 450 mm/s to 80 mm/s.Meanwhile,the load-carrying ability of water film was increased.The role of fullerenol was discussed based on observation of the wear scar by an optical interferometer and XPS characterization of the tribo-film on the wear track.
基金"863 Plan" of China(grant no. 2001AA218061, no. 2004AA218042,and no.2006AA030202)the National Natural Science Foundation(NSF) of China (grant no. 20146002,no.20236020,and no.20325621)Nano Materials Technology Pte. Ltd., Singapore
文摘This paper reviews our work on the fundamental principles of high gravity controlled precipitation (HGCP) technology, and its applications in the production of drug nanoparticles, which was carried out in a rotating packed bed (RPB). Several kinds of drug nanoparticles with narrow particle size distributions (PSDs) were successfully prepared via HGCP, including the 300-nm Cefuroxime Axetil (CFA) particles, 200–400-nm cephradine particles, 500-nm salbutamol sulfate (SS) particles (100 nm in width), and 850-nm beclomethasone dipropionate (BDP) particles, etc. Compared to drugs available in the current market, all the drug nanoparticles produced by HGCP exhibited advantages in both formulation and drug delivery, thus improving the bioavailability of drugs. HGCP is essentially a platform technology for the preparation of poorly water-soluble drug nanoparticles for oral and injection delivery, and of inhalable drugs for pulmonary delivery. Consequently, HGCP offers potential applications in the pharmaceutical industry due to its cost-effectiveness, efficient processing and the ease of scaling-up.
基金supported by the National Natural Science Foundation of China (52161135302 and 21674019)the Research Foundation of Flanders (FWO Grant No. 1298323N)+3 种基金the Natural Science Foundation of Shanghai (20ZR1401400)the Shanghai Scientific and Technological Innovation Project (18JC1410600)the Program of Shanghai Academic Research Leader (17XD1400100)the Fundamental Research Funds for the Central Universities and DHU Distinguished Young Professor Program (LZB2021002)。
文摘The creation of ultrafine alloy nanoparticles(<5 nm) that can maintain surface activity and avoid aggregation for heterogeneous catalysis has received much attention and is extremely challenging.Here,ultrafine PtRh alloy nanoparticles imprisoned by the cavities of reduced chiral covalent imine cage(PtRh@RCC3) are prepared successfully by an organic molecular cage(OMC) confinement strategy,while the soluble RCC3 can act as a homogenizer to homogenize the heterogeneous PtRh alloy in solution.Moreover,the X-ray absorption near-edge structure(XANES) results show that the RCC3 can act as an electron-acceptor to withdraw electrons from Pt,leading to the formation of higher valence Pt atoms,which is beneficial to improving the catalytic activity for the reduction of 4-nitrophenol.Attributed to the synergistic effect of Pt/Rh atoms and the unique function of the RCC3,the reaction rate constants of Pt_(1)Rh_(16)@RCC3 are 49.6,8.2,and 5.5 times than those of the Pt_(1)Rh_(16)bulk,Pt@RCC3 and Rh@RCC3,respectively.This work provides a feasible strategy to homogenize heterogeneous alloy nanoparticle catalysts in solution,showing huge potential for advanced catalytic application.
基金support from the National High-Technology Research and Development Program of China(No.2004AA616160)
文摘In recent years, silica nanoparticle aggregates （SNPAs） have been used to decrease the injection pressure of wells in low permeability reservoirs achieving good results. In order to study the mechanisms for reduction in the injection pressure of low permeability wells by the SNPA-diesel oil system injection, the microstructure of SNPAs was observed with a transmission electron microscope （TEM）. The particle size distribution of SNPAs was also measured by the laser scattering method. The viscosities of diesel oil and SNPA-diesel oil system were measured with a capillary viscometer. The effect of SNPAs on the solubility of wax in the diesel oil was experimentally studied. The influencing factors, including temperature and SNPA concentration in diesel oil, on wax solubility were analyzed. A pore-throat film displacement model （PTFDM） was built for mechanism explanation. The microstructure and size distribution analyses show that the SNPAs are in the nanometer size range. The viscosity of the SNPA-diesel oil system is lower than that of the diesel oil. The solubility of wax in the diesel oil increases greatly due to SNPA addition, the solubility ratio reaches 7.5. The solubility of wax in diesel oil increases with increases in the concentration of SNPAs in the diesel oil and with the temperature. It is proved that the addition of SNPAs to diesel oil helps remove the wax deposited near the wellbore. This maybe one of the main mechanisms for injection pressure decreases in low permeability reservoirs.
