Cantilevered pipe conveying fluid may become unstable and flutter instability would occur when the velocity of the fluid flow in the pipe exceeds a critical value.In the present study,the theoretical model of a cantil...Cantilevered pipe conveying fluid may become unstable and flutter instability would occur when the velocity of the fluid flow in the pipe exceeds a critical value.In the present study,the theoretical model of a cantilevered fluid-conveying pipe attached by an inerter-based dynamic vibration absorber(IDVA)is proposed and the stability of this dynamical system is explored.Based on linear governing equations of the pipe and the IDVA,the effects of damping coefficient,weight,inerter,location and spring stiffness of the IDVAon the critical flow velocities of the pipe system is examined.It is shown that the stability of the pipe may be significantly affected by the IDVA.In many cases,the stability of the cantilevered pipe can be enhanced by designing the parameter values of the IDVA.By solving nonlinear governing equations of the dynamical system,the nonlinear oscillations of the pipe with IDVA for sufficiently high flow velocity beyond the critical value are determined,showing that the oscillation amplitudes of the pipe can also be suppressed to some extent with a suitable design of the IDVA.展开更多
Acute liver failure(ALF),a fatal clinical disease featured with overwhelming hepatocyte necrosis,is a grand challenge in global health.However,a satisfactory therapeutic option for curing ALF is still absent,other tha...Acute liver failure(ALF),a fatal clinical disease featured with overwhelming hepatocyte necrosis,is a grand challenge in global health.However,a satisfactory therapeutic option for curing ALF is still absent,other than liver transplantation.Nanobiomaterials are currently being developed for the diagnosis and treatment of ALF.The liver can sequester most of nanoparticles from blood circulation,which becomes an intrinsic superiority for nanobiomaterials targeting hepatic diseases.Nanobiomaterials can enhance the bioavailability of free drugs,thereby significantly improving the therapeutic effects in ALF.Nanobiomaterials can also increase the liver accumulation of therapeutic agents and enable more effective targeting of the liver or specific liver cells.In addition,stimuli-responsive,optical,or magnetic nanomaterials exhibit great potential in the therapeutical,diagnostic,and imaging applications in ALF.Therefore,therapeutic agents in combination with nanobiomaterials increase the specificity of ALF therapy,diminish adverse systemic effects,and offer a multifunctional theranostic platform.Nanobiomaterial holds excellent significance and prospects in ALF theranostics.In this review,we summarize the therapeutic mechanisms and targeting strategies of various nanobiomaterials in ALF.We highlight recent developments of diverse nanomedicines for ALF therapy,diagnosis,and imaging.Furthermore,the challenges and future perspectives in the theranostics of ALF are also discussed.展开更多
Manganese(Mn)toxicity-induced leaf chlorosis limits crop production in acidic soils,but its underlying mechanisms remain unknown.The effects of excessive Mn on chlorophyll(Chl)biosynthesis in sugarcane(Saccharum offic...Manganese(Mn)toxicity-induced leaf chlorosis limits crop production in acidic soils,but its underlying mechanisms remain unknown.The effects of excessive Mn on chlorophyll(Chl)biosynthesis in sugarcane(Saccharum officinarum L.)leaves were investigated.Under Mn treatment,Chl concentration decreased with Mn accumulation and chlorosis appeared in expanding leaves.Before that,levels of the initial Chl precursor 5-aminolevulinic acid(ALA)and its downstream intermediates decreased,whereas magnesium-protoporphyrin IX monomethyl ester(MgPME)accumulated.Overaccumulation of Mn in leaves downregulated the ALA biosynthetic gene GluTR(encoding glutamyl-tRNA reductase)and MgPME conversion gene MgPMEC(encoding MgPME cyclase),upregulated the ALA biosynthesis inhibitor FLU(encoding FLUORESCENT),but had no significant effect on the expression of other Chl biosynthetic genes.The above Mn-induced changes of Chl precursors and expression of corresponding genes commenced before the Chl decline and leaf chlorosis,and were reversed by ALA supplementation.Thus,excessive Mn-induced chlorosis in sugarcane is mediated by a Chl-biosynthesis disorder resulting from the inhibition of ALA synthesis and MgPME conversion.展开更多
We propose a novel scheme for testing the equivalence principle with rotating cold polar molecules whose angular momenta are polarized at different states.Molecules in specific rotational states are selected out via t...We propose a novel scheme for testing the equivalence principle with rotating cold polar molecules whose angular momenta are polarized at different states.Molecules in specific rotational states are selected out via the hexapole state-selection technique and the gravitational acceleration g of molecules is measured by measuring the Doppler shift of the molecules free falling in the gravitational field.Some other possible methods of rotating molecules and measuring g are also mentioned.Molecules,as the test masses,have higher rotating speed and smaller dimension in comparison with mechanical gyroscopes and may open a new way for testing the equivalence principle and the possible coupling between rotation and gravity.展开更多
基金The authors gratefully acknowledge the support provided by the National Natural Science Foundation of China(Nos.11622216,11672115 and 11972167).
文摘Cantilevered pipe conveying fluid may become unstable and flutter instability would occur when the velocity of the fluid flow in the pipe exceeds a critical value.In the present study,the theoretical model of a cantilevered fluid-conveying pipe attached by an inerter-based dynamic vibration absorber(IDVA)is proposed and the stability of this dynamical system is explored.Based on linear governing equations of the pipe and the IDVA,the effects of damping coefficient,weight,inerter,location and spring stiffness of the IDVAon the critical flow velocities of the pipe system is examined.It is shown that the stability of the pipe may be significantly affected by the IDVA.In many cases,the stability of the cantilevered pipe can be enhanced by designing the parameter values of the IDVA.By solving nonlinear governing equations of the dynamical system,the nonlinear oscillations of the pipe with IDVA for sufficiently high flow velocity beyond the critical value are determined,showing that the oscillation amplitudes of the pipe can also be suppressed to some extent with a suitable design of the IDVA.
基金supported by the National Key Research and Development Program of China(2019YFA0111300)the National Natural Science Foundation of China(21907113,51903256,32001012)the Guangdong Province Science and Technology Innovation Special Fund(International Scientific Cooperation,2018A050506035).
文摘Acute liver failure(ALF),a fatal clinical disease featured with overwhelming hepatocyte necrosis,is a grand challenge in global health.However,a satisfactory therapeutic option for curing ALF is still absent,other than liver transplantation.Nanobiomaterials are currently being developed for the diagnosis and treatment of ALF.The liver can sequester most of nanoparticles from blood circulation,which becomes an intrinsic superiority for nanobiomaterials targeting hepatic diseases.Nanobiomaterials can enhance the bioavailability of free drugs,thereby significantly improving the therapeutic effects in ALF.Nanobiomaterials can also increase the liver accumulation of therapeutic agents and enable more effective targeting of the liver or specific liver cells.In addition,stimuli-responsive,optical,or magnetic nanomaterials exhibit great potential in the therapeutical,diagnostic,and imaging applications in ALF.Therefore,therapeutic agents in combination with nanobiomaterials increase the specificity of ALF therapy,diminish adverse systemic effects,and offer a multifunctional theranostic platform.Nanobiomaterial holds excellent significance and prospects in ALF theranostics.In this review,we summarize the therapeutic mechanisms and targeting strategies of various nanobiomaterials in ALF.We highlight recent developments of diverse nanomedicines for ALF therapy,diagnosis,and imaging.Furthermore,the challenges and future perspectives in the theranostics of ALF are also discussed.
基金supported by the National Natural Science Foundation of China(31660593)China Postdoctoral Science Foundation(2020M683620XB)+1 种基金Guangxi Natural Science Foundation(2021GXNSFAA075017,2021GXNSFAA220008)Science and Technology Major Project of Guangxi(GK2018-266-Z01)。
文摘Manganese(Mn)toxicity-induced leaf chlorosis limits crop production in acidic soils,but its underlying mechanisms remain unknown.The effects of excessive Mn on chlorophyll(Chl)biosynthesis in sugarcane(Saccharum officinarum L.)leaves were investigated.Under Mn treatment,Chl concentration decreased with Mn accumulation and chlorosis appeared in expanding leaves.Before that,levels of the initial Chl precursor 5-aminolevulinic acid(ALA)and its downstream intermediates decreased,whereas magnesium-protoporphyrin IX monomethyl ester(MgPME)accumulated.Overaccumulation of Mn in leaves downregulated the ALA biosynthetic gene GluTR(encoding glutamyl-tRNA reductase)and MgPME conversion gene MgPMEC(encoding MgPME cyclase),upregulated the ALA biosynthesis inhibitor FLU(encoding FLUORESCENT),but had no significant effect on the expression of other Chl biosynthetic genes.The above Mn-induced changes of Chl precursors and expression of corresponding genes commenced before the Chl decline and leaf chlorosis,and were reversed by ALA supplementation.Thus,excessive Mn-induced chlorosis in sugarcane is mediated by a Chl-biosynthesis disorder resulting from the inhibition of ALA synthesis and MgPME conversion.
基金Supported by the National Basic Research Program of China under Grant No 2010CB832806the National Natural Science Foundation of China under Grant No 41127002.
文摘We propose a novel scheme for testing the equivalence principle with rotating cold polar molecules whose angular momenta are polarized at different states.Molecules in specific rotational states are selected out via the hexapole state-selection technique and the gravitational acceleration g of molecules is measured by measuring the Doppler shift of the molecules free falling in the gravitational field.Some other possible methods of rotating molecules and measuring g are also mentioned.Molecules,as the test masses,have higher rotating speed and smaller dimension in comparison with mechanical gyroscopes and may open a new way for testing the equivalence principle and the possible coupling between rotation and gravity.
