In order to enhance the biomethane production from corn stover, choosing effective pretreatment is one of the necessary steps before starting anaerobic digestion(AD).This study was aimed to analyze the effectiveness o...In order to enhance the biomethane production from corn stover, choosing effective pretreatment is one of the necessary steps before starting anaerobic digestion(AD).This study was aimed to analyze the effectiveness of freezing–thawing with ammonia pretreatment on substance degradation and AD performance of corn stover.Three ammonia concentrations(2%, 4%, and 6%) with two different moisture contents(50% and 70%) were used to pretreat the corn stover at two temperatures(-20 ℃ and 20 ℃).The result showed that an optimum pretreatment condition for corn stover was at the temperature of -20 ℃, moisture content of 70% and ammonia concentration of 2%.Under the optimum pretreatment condition, the maximum biomethane yield reached 261 ml·(g VS)^(-1), which was 41.08% higher than that of the untreated.Under different pretreatment conditions,the highest loss of lignin at -20 ℃ with 2% ammonia concentration was 63.36% compared with the untreated.The buffer capacity of AD system was also improved after the freezing–thawing with ammonia pretreatment.Therefore, the freezing–thawing with ammonia pretreatment can be used to improve AD performance for corn stover.This study provides further insight for exploring an efficient freezing–thawing with ammonia pretreatment strategy to enhance AD performance for the practical application.展开更多
In this paper, we present a meshless Galerkin scheme of boundary integral equations （BIEs）, known as the Galerkin boundary node method （GBNM）, for two-dimensional ex- terior Neumann problems that combines the movi...In this paper, we present a meshless Galerkin scheme of boundary integral equations （BIEs）, known as the Galerkin boundary node method （GBNM）, for two-dimensional ex- terior Neumann problems that combines the moving least-squares （MLS） approximations and a variational formulation of BIEs. In this approach, boundary conditions can be imple- mented directly despite the MLS approximations lack the delta function property. Besides, the GBNM keeps the symmetry and positive definiteness of the variational problems. A rigorous error analysis and convergence study of the method is presented in Sobolev spaces. Numerical examples are also given to illustrate the capability of the method.展开更多
Brain ischemia is the second leading cause of death and the third leading cause of disability in the world.Systemic delivery of microRNA,a class of molecules that regulate the expression of cellular proteins associate...Brain ischemia is the second leading cause of death and the third leading cause of disability in the world.Systemic delivery of microRNA,a class of molecules that regulate the expression of cellular proteins associated with angiogenesis,cell growth,proliferation and differentiation,holds great promise for the treatment of brain ischemia.However,their therapeutic efficacy has been hampered by poor delivery efficiency of microRNA.We report herein a platform technology based on microRNA nanocapsules,which enables their effective delivery to the disease sites in the brain.Exemplified by microRNA-21,intravenous injection of the nanocapsules into a rat model of cerebral ischemia could effectively ameliorate the infarct volume,neurological deficit and histopathological severity.展开更多
基金Supported by the Key Technologies R&D Program of China(2016YFD0501402)
文摘In order to enhance the biomethane production from corn stover, choosing effective pretreatment is one of the necessary steps before starting anaerobic digestion(AD).This study was aimed to analyze the effectiveness of freezing–thawing with ammonia pretreatment on substance degradation and AD performance of corn stover.Three ammonia concentrations(2%, 4%, and 6%) with two different moisture contents(50% and 70%) were used to pretreat the corn stover at two temperatures(-20 ℃ and 20 ℃).The result showed that an optimum pretreatment condition for corn stover was at the temperature of -20 ℃, moisture content of 70% and ammonia concentration of 2%.Under the optimum pretreatment condition, the maximum biomethane yield reached 261 ml·(g VS)^(-1), which was 41.08% higher than that of the untreated.Under different pretreatment conditions,the highest loss of lignin at -20 ℃ with 2% ammonia concentration was 63.36% compared with the untreated.The buffer capacity of AD system was also improved after the freezing–thawing with ammonia pretreatment.Therefore, the freezing–thawing with ammonia pretreatment can be used to improve AD performance for corn stover.This study provides further insight for exploring an efficient freezing–thawing with ammonia pretreatment strategy to enhance AD performance for the practical application.
文摘In this paper, we present a meshless Galerkin scheme of boundary integral equations （BIEs）, known as the Galerkin boundary node method （GBNM）, for two-dimensional ex- terior Neumann problems that combines the moving least-squares （MLS） approximations and a variational formulation of BIEs. In this approach, boundary conditions can be imple- mented directly despite the MLS approximations lack the delta function property. Besides, the GBNM keeps the symmetry and positive definiteness of the variational problems. A rigorous error analysis and convergence study of the method is presented in Sobolev spaces. Numerical examples are also given to illustrate the capability of the method.
基金supported by the National Key Research and Development Program of China(No.2019YFA0903801)the National Natural Science Foundation of China(Nos.52073015,51773151,52003021,and 81671169)+2 种基金Tianjin Municipal Health Bureau(No.2010KY11)Postdoctoral Science Foundation of China(No.2015M580212)Fundamental Research Funds for the Central Universities(No.ZY2006).
文摘Brain ischemia is the second leading cause of death and the third leading cause of disability in the world.Systemic delivery of microRNA,a class of molecules that regulate the expression of cellular proteins associated with angiogenesis,cell growth,proliferation and differentiation,holds great promise for the treatment of brain ischemia.However,their therapeutic efficacy has been hampered by poor delivery efficiency of microRNA.We report herein a platform technology based on microRNA nanocapsules,which enables their effective delivery to the disease sites in the brain.Exemplified by microRNA-21,intravenous injection of the nanocapsules into a rat model of cerebral ischemia could effectively ameliorate the infarct volume,neurological deficit and histopathological severity.
