Objective:Angiogenesis is the development of new blood vessels.The ion channels on endothelium play a vital action in cell proliferation and so in the related angiogenesis.We aimed to investigate the anti-angiogenic e...Objective:Angiogenesis is the development of new blood vessels.The ion channels on endothelium play a vital action in cell proliferation and so in the related angiogenesis.We aimed to investigate the anti-angiogenic effects of Mefloquine(Cl-channel blocker) and4-Aminopyridine(K+ channel blocker).Methods:The anti-angiogenic activities of Mefloquine and 4-Aminopyridine(4-AP)were investigated by in-vivo(sponge implantation method),in-vitro(aortic ring assay)and in-ovo(CAM,Chick Chorioallantoic membrane) methods.The standard antiangiogenic drug used was Bevacizumab.Results:In the CAM assay,both the ion channel blockers exhibited noticeable antiangiogenic activity at the concentrations of 10-5M and 10-4M where they significantly exhibited ant proliferative activity by inhibiting the new blood vessel formation.For the further confirmation anti-angiogenic activity was evaluated in vitro and in vivo.In Rat aortic ring assay reduction in the area of sprouts were observed with 40 m M of 4-AP and7 m M of Mefloquine.A significant reduction in weight of sponges,number of blood vessels formed and hemoglobin content were observed at 4.2 mg/kg of 4-AP and 20 mg/kg and 30 mg/kg of Mefloquine.Conclusions:These scientific findings indicate the use of Mefloquine and 4-Aminopyridine in pathological situations involving excessive angiogenesis.Negative regulation of cell volume,cell migration and proliferation of blood vessels may be the underlying molecular mechanisms.展开更多
A three-dimensional simulation of a steady-state amplifier model of a long-wavelength free-electron laser （FEL） with realizable helical wiggler and ion-channel guiding is presented. The set of coupled nonlinear diff...A three-dimensional simulation of a steady-state amplifier model of a long-wavelength free-electron laser （FEL） with realizable helical wiggler and ion-channel guiding is presented. The set of coupled nonlinear differential equations for electron orbits and fields of TE 11 mode in a cylindrical waveguide are solved numerically by the Runge–Kutta algorithm with averages calculated by the Gaussian quadrature technique. Self-fields and space-charge effects are neglected, and the electron beam is assumed to be cold and slippage is ignored. The parameters correspond to the Compton regime. Evolution of the radiation power and growth rate along the wiggler is studied. Ion-channel density is chosen to obtain optimum efficiency. Simulations are preformed for the FEL operating in the neighborhood of 35 GHz and 16.5 GHz for the electron beam energies of 250 keV and 400 keV, respectively. The result of the saturated efficiency was found to be in good agreement with the simple estimation based on the phase-trapping model.展开更多
Amplification of an electromagnetic wave by a free electron laser （FEL） with a helical wiggler and an ion channel with a periodically varying ion density is examined. The relativistic equation of motion for a single...Amplification of an electromagnetic wave by a free electron laser （FEL） with a helical wiggler and an ion channel with a periodically varying ion density is examined. The relativistic equation of motion for a single electron in the combined wiggler and the periodic ionbchannel fields is solved and the classes of possible trajectories in this configuration are discussed. The gain equation for the FEL in the low-gain-per-pass lirnit is obtained by adding the effect of the periodic ion channel. Numerical calculation is employed to analyse the gain induced by the effects of the non-uniform ion density. The variation of gain with ion-channel density is demonstrated. It is shown that there is a gain enhancement for group I orbits in the presence of a non-uniform ion-channel but not in a uniform one. It is also shown that periodic ion-channel guiding is used to reach the maximum peak gain in a low ion-channel frequency （low ion density）.展开更多
In this paper, a new mechanism of electromagnetic instability, the induced ion-channel instability, is stud- ied. It is based on the transverse driven betatron oscillation of relativistic electron beam induced by an a...In this paper, a new mechanism of electromagnetic instability, the induced ion-channel instability, is stud- ied. It is based on the transverse driven betatron oscillation of relativistic electron beam induced by an additional magnetic undulator with a period close to the betatron wavelength in an ion channel. As its amplitude is sensitive to the electron beam energy, the driven betatron oscillation may determine electron beam grouping in the ponderomotive potential by selecting the undulator strength and period, and it provides a new mechanism of electron bunching, re- sulting in electromagnetic instability. Under proper condition, a new free-electron laser based on this mechanism may be realized.展开更多
This paper addresses the formulae and numerical issues related to the possibility that fast wave may be grown when a relativistic electron beam through an ion channel in a cylindrical metal waveguide. To derive the di...This paper addresses the formulae and numerical issues related to the possibility that fast wave may be grown when a relativistic electron beam through an ion channel in a cylindrical metal waveguide. To derive the dispersion equations of the beam-wave interaction, it solves relativistic Lorentz equation and Maxwell＇s equations for appropriate boundary conditions. It has been found in this waveguide structure that the TM0m modes are the rational operating modes of coupling between the electromagnetic modes and the betatron modes. The interaction of the dispersion curves of the electromagnetic TM0m modes and the upper betatron modes is studied. The growth rates of the wave are obtained, and the effects of the beam radius, the beam energy, the plasma frequency, and the beam plasma frequency on the wave growth rate are numerically calculated and discussed.展开更多
Atrial fibrillation(AF) is the most commonly encountered clinical arrhythmia associated with pronounced mortality and morbidity, which are related to palpitations, fainting, congestive heart failure, and stroke. Prolo...Atrial fibrillation(AF) is the most commonly encountered clinical arrhythmia associated with pronounced mortality and morbidity, which are related to palpitations, fainting, congestive heart failure, and stroke. Prolonged episodes of AF promote AF persistence mainly due to electrical remodelling that alters ion-channel expression and/or function. Micro RNAs(mi RNAs), a new class of noncoding mR NAs of around 22 nucleotides in length, have recently emerged as one of the key players in the geneexpression regulatory networks. The potential roles of miR NAs in controlling AF have recently been investigated. Several recent studies have provided promising results for a better understanding of the molecular mechanisms of AF. In this review, we summarize the mechanism of miR NAs as regulators of ion-channel gene expression and their role in causing AF through electrical remodelling.展开更多
Electron acceleration in the inverse free electron laser （IFEL） with a helical wiggler in the presence of ion-channel guiding and axial magnetic field is investigated in this article. The effects of tapering wiggler...Electron acceleration in the inverse free electron laser （IFEL） with a helical wiggler in the presence of ion-channel guiding and axial magnetic field is investigated in this article. The effects of tapering wiggler amplitude and axial magnetic field are calculated for the electron acceleration. In free electron lasers, electron beams lose energy through radiation while in IFEL electron beams gain energy from the laser. The equation of electron motion and the equation of energy exchange between a single electron and electromagnetic waves are derived and then solved numerically using the fourth order Runge-Kutta method. The tapering effects of a wiggler magnetic field on electron acceleration are investigated and the results show that the electron acceleration increases in the case of a tapered wiggler magnetic field with a proper taper constant.展开更多
文摘Objective:Angiogenesis is the development of new blood vessels.The ion channels on endothelium play a vital action in cell proliferation and so in the related angiogenesis.We aimed to investigate the anti-angiogenic effects of Mefloquine(Cl-channel blocker) and4-Aminopyridine(K+ channel blocker).Methods:The anti-angiogenic activities of Mefloquine and 4-Aminopyridine(4-AP)were investigated by in-vivo(sponge implantation method),in-vitro(aortic ring assay)and in-ovo(CAM,Chick Chorioallantoic membrane) methods.The standard antiangiogenic drug used was Bevacizumab.Results:In the CAM assay,both the ion channel blockers exhibited noticeable antiangiogenic activity at the concentrations of 10-5M and 10-4M where they significantly exhibited ant proliferative activity by inhibiting the new blood vessel formation.For the further confirmation anti-angiogenic activity was evaluated in vitro and in vivo.In Rat aortic ring assay reduction in the area of sprouts were observed with 40 m M of 4-AP and7 m M of Mefloquine.A significant reduction in weight of sponges,number of blood vessels formed and hemoglobin content were observed at 4.2 mg/kg of 4-AP and 20 mg/kg and 30 mg/kg of Mefloquine.Conclusions:These scientific findings indicate the use of Mefloquine and 4-Aminopyridine in pathological situations involving excessive angiogenesis.Negative regulation of cell volume,cell migration and proliferation of blood vessels may be the underlying molecular mechanisms.
文摘A three-dimensional simulation of a steady-state amplifier model of a long-wavelength free-electron laser （FEL） with realizable helical wiggler and ion-channel guiding is presented. The set of coupled nonlinear differential equations for electron orbits and fields of TE 11 mode in a cylindrical waveguide are solved numerically by the Runge–Kutta algorithm with averages calculated by the Gaussian quadrature technique. Self-fields and space-charge effects are neglected, and the electron beam is assumed to be cold and slippage is ignored. The parameters correspond to the Compton regime. Evolution of the radiation power and growth rate along the wiggler is studied. Ion-channel density is chosen to obtain optimum efficiency. Simulations are preformed for the FEL operating in the neighborhood of 35 GHz and 16.5 GHz for the electron beam energies of 250 keV and 400 keV, respectively. The result of the saturated efficiency was found to be in good agreement with the simple estimation based on the phase-trapping model.
文摘Amplification of an electromagnetic wave by a free electron laser （FEL） with a helical wiggler and an ion channel with a periodically varying ion density is examined. The relativistic equation of motion for a single electron in the combined wiggler and the periodic ionbchannel fields is solved and the classes of possible trajectories in this configuration are discussed. The gain equation for the FEL in the low-gain-per-pass lirnit is obtained by adding the effect of the periodic ion channel. Numerical calculation is employed to analyse the gain induced by the effects of the non-uniform ion density. The variation of gain with ion-channel density is demonstrated. It is shown that there is a gain enhancement for group I orbits in the presence of a non-uniform ion-channel but not in a uniform one. It is also shown that periodic ion-channel guiding is used to reach the maximum peak gain in a low ion-channel frequency （low ion density）.
基金Partially supported by the Major State Basic Research Development Programme of China under Grant No.2002CB713600,the Shanghai Science and Technology Council under Grant No.02QF14059and the Exploration Project of Knowledge Innovation Program of CAS.
文摘In this paper, a new mechanism of electromagnetic instability, the induced ion-channel instability, is stud- ied. It is based on the transverse driven betatron oscillation of relativistic electron beam induced by an additional magnetic undulator with a period close to the betatron wavelength in an ion channel. As its amplitude is sensitive to the electron beam energy, the driven betatron oscillation may determine electron beam grouping in the ponderomotive potential by selecting the undulator strength and period, and it provides a new mechanism of electron bunching, re- sulting in electromagnetic instability. Under proper condition, a new free-electron laser based on this mechanism may be realized.
基金Project supported in part by the National Natural Science Foundation of China (Grant Nos. 10775100 and 90503008)the Science Foundation of China Academy of Engineering Physics (Grant No. 10576019)the Fund of Theoretical Nuclear Physics Center,National Laboratory of Heavy Ion Accelerator Facility of Lanzhou
文摘This paper addresses the formulae and numerical issues related to the possibility that fast wave may be grown when a relativistic electron beam through an ion channel in a cylindrical metal waveguide. To derive the dispersion equations of the beam-wave interaction, it solves relativistic Lorentz equation and Maxwell＇s equations for appropriate boundary conditions. It has been found in this waveguide structure that the TM0m modes are the rational operating modes of coupling between the electromagnetic modes and the betatron modes. The interaction of the dispersion curves of the electromagnetic TM0m modes and the upper betatron modes is studied. The growth rates of the wave are obtained, and the effects of the beam radius, the beam energy, the plasma frequency, and the beam plasma frequency on the wave growth rate are numerically calculated and discussed.
基金Supported by Grants BFU2012-38111(Ministerio de Economíay Competitividad,Gobierno de Espaa),Nos.CTS-1614,P08-CTS-03878,BIO-302(Junta de Andalucia)and AFM2012-16074(AFM)
文摘Atrial fibrillation(AF) is the most commonly encountered clinical arrhythmia associated with pronounced mortality and morbidity, which are related to palpitations, fainting, congestive heart failure, and stroke. Prolonged episodes of AF promote AF persistence mainly due to electrical remodelling that alters ion-channel expression and/or function. Micro RNAs(mi RNAs), a new class of noncoding mR NAs of around 22 nucleotides in length, have recently emerged as one of the key players in the geneexpression regulatory networks. The potential roles of miR NAs in controlling AF have recently been investigated. Several recent studies have provided promising results for a better understanding of the molecular mechanisms of AF. In this review, we summarize the mechanism of miR NAs as regulators of ion-channel gene expression and their role in causing AF through electrical remodelling.
文摘Electron acceleration in the inverse free electron laser （IFEL） with a helical wiggler in the presence of ion-channel guiding and axial magnetic field is investigated in this article. The effects of tapering wiggler amplitude and axial magnetic field are calculated for the electron acceleration. In free electron lasers, electron beams lose energy through radiation while in IFEL electron beams gain energy from the laser. The equation of electron motion and the equation of energy exchange between a single electron and electromagnetic waves are derived and then solved numerically using the fourth order Runge-Kutta method. The tapering effects of a wiggler magnetic field on electron acceleration are investigated and the results show that the electron acceleration increases in the case of a tapered wiggler magnetic field with a proper taper constant.
