On May 28, the State Electricity Regulatory Commission and the China Electricity Council jointly held a conference releasing the electric reliability indices in 2009 in Beijing.
In this paper, the effect of electric boundary conditions on Mode I crack propagation in ferroelectric ceramics is studied by using both linear and nonlinear piezoelectric fracture mechanics. In linear analysis, imper...In this paper, the effect of electric boundary conditions on Mode I crack propagation in ferroelectric ceramics is studied by using both linear and nonlinear piezoelectric fracture mechanics. In linear analysis, impermeable cracks under open circuit and short circuit are analyzed using the Stroh formalism and a rescaling method. It is shown that the energy release rate in short circuit is larger than that in open circuit. In nonlinear analysis, permeable crack conditions are used and the nonlinear effect of domain switching near a crack tip is considered using an energy-based switching criterion proposed by Hwang et al.（Acta Metal. Mater.,1995）. In open circuit, a large depolarization field induced by domain switching makes switching much more diffcult than that in short circuit. Analysis shows that the energy release rate in short circuit is still larger than that in open circuit, and is also larger than the linear result. Consequently,whether using linear or nonlinear fracture analysis, a crack is found easier to propagate in short circuit than in open circuit, which is consistent with the experimental observations of Kounga Njiwa et al.（Eng. Fract. Mech., 2006）.展开更多
Direct messenger ribonucleic acid(mRNA)delivery to target cells or tissues has revolutionized the field of biotechnology.However,the applicability of regenerative medicine is limited by the technical difficulties of v...Direct messenger ribonucleic acid(mRNA)delivery to target cells or tissues has revolutionized the field of biotechnology.However,the applicability of regenerative medicine is limited by the technical difficulties of various mRNA-loaded nanocarriers.Herein,we report a new conductive hybrid film that could guide osteogenic differentiation of human adipose-derived mesenchymal stem cells(hADMSCs)via electrically controlled mRNA delivery.To find optimal electrical conductivity and mRNAloading capacity,the polypyrrole-graphene oxide(PPy-GO)hybrid film was electropolymerized on indium tin oxide substrates.We found that the fluorescein sodium salt,a molecule partially mimicking the physical and chemical properties of mRNAs,can be effectively absorbed and released by electrical stimulation(ES).The hADMSCs cultivated on the PPy-GO hybrid film loaded with pre-osteogenic mRNAs showed the highest osteogenic differentiation under electrical stimulation.This platform can load various types of RNAs thus highly promising as a new nucleic acid delivery tool for the development of stem cell-based therapeutics.展开更多
文摘On May 28, the State Electricity Regulatory Commission and the China Electricity Council jointly held a conference releasing the electric reliability indices in 2009 in Beijing.
基金supported by the National Natural Science Foundation of China(11002002 and 11090331)
文摘In this paper, the effect of electric boundary conditions on Mode I crack propagation in ferroelectric ceramics is studied by using both linear and nonlinear piezoelectric fracture mechanics. In linear analysis, impermeable cracks under open circuit and short circuit are analyzed using the Stroh formalism and a rescaling method. It is shown that the energy release rate in short circuit is larger than that in open circuit. In nonlinear analysis, permeable crack conditions are used and the nonlinear effect of domain switching near a crack tip is considered using an energy-based switching criterion proposed by Hwang et al.（Acta Metal. Mater.,1995）. In open circuit, a large depolarization field induced by domain switching makes switching much more diffcult than that in short circuit. Analysis shows that the energy release rate in short circuit is still larger than that in open circuit, and is also larger than the linear result. Consequently,whether using linear or nonlinear fracture analysis, a crack is found easier to propagate in short circuit than in open circuit, which is consistent with the experimental observations of Kounga Njiwa et al.（Eng. Fract. Mech., 2006）.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(Nos.NRF-2019M3A9H_(2)031820,NRF-2021R1A2C1010747,and NRF-2022R1A2C4002217)Korean Fund for Regenerative Medicine funded by Ministry of Science and ICT,and Ministry of Health and Welfare(Grant No.RS-2022-00070316)+1 种基金the Bio&Medical Technology Development Program funded by the Ministry of Science,ICT and Future Planning,Republic of Korea(NRF-2017M3A9E4047243)d K.S.also thankful for The Council of Higher Education(CoHE,100/2000)PhD Scholarship Program,Turkey.
文摘Direct messenger ribonucleic acid(mRNA)delivery to target cells or tissues has revolutionized the field of biotechnology.However,the applicability of regenerative medicine is limited by the technical difficulties of various mRNA-loaded nanocarriers.Herein,we report a new conductive hybrid film that could guide osteogenic differentiation of human adipose-derived mesenchymal stem cells(hADMSCs)via electrically controlled mRNA delivery.To find optimal electrical conductivity and mRNAloading capacity,the polypyrrole-graphene oxide(PPy-GO)hybrid film was electropolymerized on indium tin oxide substrates.We found that the fluorescein sodium salt,a molecule partially mimicking the physical and chemical properties of mRNAs,can be effectively absorbed and released by electrical stimulation(ES).The hADMSCs cultivated on the PPy-GO hybrid film loaded with pre-osteogenic mRNAs showed the highest osteogenic differentiation under electrical stimulation.This platform can load various types of RNAs thus highly promising as a new nucleic acid delivery tool for the development of stem cell-based therapeutics.
