Elastography-based liver stiffness measurement(LSM) is a non-invasive tool for estimating liver fibrosis but also provides an estimate for the severity of portal hypertension in patients with advanced chronic liver di...Elastography-based liver stiffness measurement(LSM) is a non-invasive tool for estimating liver fibrosis but also provides an estimate for the severity of portal hypertension in patients with advanced chronic liver disease(ACLD). The presence of varices and especially of varices needing treatment(VNT) indicates distinct prognostic stages in patients with compensated ACLD(cACLD). The Baveno VI guidelines suggested a simple algorithm based on LSM < 20 kPa(by transient elastography, TE) and platelet count > 150 G/L for ruling-out VNT in patients with cACLD. These(and other) TE-based LSM cut-offs have been evaluated for VNT screening in different liver disease etiologies. Novel point shear-wave elastography(pSWE) and two-dimensional shear wave elastography(2D-SWE) methodologies for LSM have also been evaluated for their ability to screen for "any" varices and for VNT. Finally, the measurement of spleen stiffness(SSM) by elastography(mainly by pSWE and 2D-SWE) may represent another valuable screening tool for varices. Here, we summarize the current literature on elastography-based prediction of "any" varices and VNT. Finally,we have summarized the published LSM and SSM cut-offs in clinically useful scale cards.展开更多
In this study, the essence and origin of the magnetic constant are discussed and a mechanism that allows real estimations of the magnetic constant based upon the vacuum density description is proposed. By considering ...In this study, the essence and origin of the magnetic constant are discussed and a mechanism that allows real estimations of the magnetic constant based upon the vacuum density description is proposed. By considering the vacuum as a liquid with a measurable density and the electron as a vortex, hydrodynamic laws are applied to measure the diminished momentum of a rotating electron in a vacuum, thus obtaining a value similar to the experimentally derived value of the magnetic constant. A consequence of this description is that the magnetic constant can be expressed as the shear stress per unit time of the vacuum;this means that it is an observable vacuum parameter and not a fundamental constant.展开更多
The present work aims at identifying Nb-Ta-, Zr-Hf-, REE-, Th-U-bearing two-mica granite from geological, geophysical cross-sections and mineral chemistry studies from three boreholes at G. El Sela shear zone. Microsc...The present work aims at identifying Nb-Ta-, Zr-Hf-, REE-, Th-U-bearing two-mica granite from geological, geophysical cross-sections and mineral chemistry studies from three boreholes at G. El Sela shear zone. Microscopically, the three boreholes are composed mainly of two-mica granite. They are composed of K-feldspar, plagioclase, quartz, biotite and muscovite. Accessories are pyrite, zircon, fluorite, rutile, monazite with Th-U-mineralization identified by scanning electron microscope (SEM) and electron probe-microanalyses (EPMA). Chlorite, muscovite, sericite, kaolinite are secondary minerals. Geochemically, two-mica granite boreholes are A-type granites and peraluminous characteristics. They are enriched in large ion lithophile elements (LILE;Ba, Rb and Sr), high field strength elements (Y, Zr and Nb), and LREE but depleted in HREE with negative Eu anomaly. U-enrichment associated with chloritization, muscovitization, albitization, sericitization, kaolinization and argillization results from convective hydrothermal circulation of fluids through brittle structures along the ENE-WSW main shear zone. The ratios Nb/Ta (7.7 - 17.7) and Zr/Hf (16.9 - 26.4) are relatively enriched in the lighter isovalents Ta and Hf. The accessory minerals observed in the two-mica granites are represented by metallic sulfides (pyrite, arsenopyrite, chalcopyrite, galena and sphalerite), Nb-rutile, Hf-zircon, fluorite, monazite, columbite, betafite, thorite, phosphothorite, uranothorite, brannerite, uraninite, coffinite and pitchblende at G. El Sela shear zone. Uraninite with a low Th content indicates a hydrothermal origin of U-mineralization, Thorite, uranothorite, monazite and zircon is the main uranium bearing minerals of magmatic origin within the enclosing granite. The primary U-mineralization has been observed in two boreholes. In order to illustrate the geophysical signature of El Sela U-mineralization, the radiometric, magnetic, and VLF-EM data as well as radon concentration are included. The magnetic, electrical conductivity展开更多
This article presents a study we have made of one class of coherent structures of the tripolar vortex. Considering the sheared flow and sheared magnetic field which are common in the thermonuclear plasma and space pla...This article presents a study we have made of one class of coherent structures of the tripolar vortex. Considering the sheared flow and sheared magnetic field which are common in the thermonuclear plasma and space plasma, we have simulated the dynamics of the tripolar vortex. The results show that the tripolar vortex is largely stable in most cases, but a strongly sheared magnetic field will make the structure less stable, and lead it to decays into single vortices with the large space scale. These results are consistent with findings from former research about the dipolar vortex.展开更多
Characteristics of the magnetic-island-induced ion temperature gradient （MITG） mode are studied through gyrofluid simulations in the slab geometry, focusing on the effects of Landau damping, equilibrium magnetic she...Characteristics of the magnetic-island-induced ion temperature gradient （MITG） mode are studied through gyrofluid simulations in the slab geometry, focusing on the effects of Landau damping, equilibrium magnetic shear （EMS）, and pressure flattening. It is shown that the magnetic island may enhance the Landau damping of the system by inducing the radial magnetic field. Moreover, the radial eigenmode numbers of most MITG poloidal harmonics are increased by the magnetic island so that the MITG mode is destabilized in the low EMS regime. In addition, the pressure profile flattening effect inside a magnetic island hardly affects the growth of the whole MITG mode, while it has different local effects near the O-point and the X-point regions. In comparison with the non-zero-order perturbations, only the quasi-linear flattening effect due to the zonal pressure is the effective component to impact the growth rate of the mode.展开更多
Magnetic reconnection at the high-latitude magnetopause is studied using 2.5-dimensional Hall-MHD simulation. Concentric flow vortices and magnetic islands appear when both Hall effect and sheared flow are considered....Magnetic reconnection at the high-latitude magnetopause is studied using 2.5-dimensional Hall-MHD simulation. Concentric flow vortices and magnetic islands appear when both Hall effect and sheared flow are considered. Plasma mixing across the magnetopause occurs in the presence of the flow vortices. Reconnected structure generated in the vicinity of the subsolar point changes its geometry with increasing flow shear while moving to high latitudes. In the presence of flow shear, with the Hall-MHD reconnection a higher reconnection rate than with the traditional MHD is obtained. The out-of-plane components of flow and magnetic field produced by the Hall current are redistributed under the action of the flow shear, which makes the plasma transport across the boundaries more complicated. The simulation results provide some help in understanding the dynamic processes at the high latitude magnetopause.展开更多
The linear evolution of a resistive wall mode(RWM)with magnetic shears was analytically studied in a cylindrical geometry.The incompressible magnetohydrodynamic(MHD)equations were solved by the Fourier analysis method...The linear evolution of a resistive wall mode(RWM)with magnetic shears was analytically studied in a cylindrical geometry.The incompressible magnetohydrodynamic(MHD)equations were solved by the Fourier analysis method,and various equilibrium magnetic fields were considered.The shear in the magnetic field had an unstable effect on the linear evolution of the RWM.The linear growth rate increased obviously with increase of the magnetic shear rate for higher magnetic shears.Slow plasma rotation could stabilize the RWM with low magnetic shears,but the plasma rotation could not stabilize the RWM with high magnetic shears.The stabilizing effects of the wall conductivity on the RWM are more efficient for lager magnetic shear.展开更多
In this work we report that after single-walled carbon nanotubes(SWNTs) are sheared with a pair of titanium scissors,the magnetization becomes larger than that of the corresponding pristine ones. The magnetization inc...In this work we report that after single-walled carbon nanotubes(SWNTs) are sheared with a pair of titanium scissors,the magnetization becomes larger than that of the corresponding pristine ones. The magnetization increases proportionally with the number of SWNTs with sheared ends, suggesting that there exist magnetic moments at the sheared ends of SWNTs.By using the coefficient of this linear relation, the average magnetic moment is estimated to be 41.5 ± 9.8 μB(Bohr magneton) per carbon atom in the edge state at temperature of 300.0 K, suggesting that ultrahigh magnetic fields can be produced. The dangling sigma and pi bonds of the carbon atoms at sheared ends play important roles in determining the unexpectedly high magnetic moments, which may have great potential applications.展开更多
The flow of the weak electrolyte solution can be controlled by Lorentz force achieved with the suitable magnetic and electric fields, and it has the advantages of vortex street suppression, drag reduction, lift enhanc...The flow of the weak electrolyte solution can be controlled by Lorentz force achieved with the suitable magnetic and electric fields, and it has the advantages of vortex street suppression, drag reduction, lift enhancement and oscillatory suppression for the flow over a bluff body. The electro-magnetic control of vortex-induced vibration (VIV) of a circular cylinder in the shear flow was investigated numerically in the exponential-polar coordinates attached on the moving cylinder for Re=150. With the effect of background vorticity, the vortex street of VIV cylinder was composed of two parallel rows with an opposite sign of the vortices which inclines toward the lower side and the strength of upper vortex is larger than that of lower vortex. The lift force vibrated periodically with the effect of vortex shedding and the mean value was negative due to the background vorticity. The Lorentz force for controlling the VIV cylinder was classified into the field Lorentz force and the wall Lorentz force. The field Lorentz force suppresses the lift oscillation, and in turn, suppresses the VIV, whereas the wall Lorentz force increases the lift.展开更多
This article investigates the colloidal study for water and ethylene glycol based nanofluids.The effects of Lorentz forces and thermal radiation are considered.The process of non-dimensionalities of governing equation...This article investigates the colloidal study for water and ethylene glycol based nanofluids.The effects of Lorentz forces and thermal radiation are considered.The process of non-dimensionalities of governing equations is carried out successfully by means of similarity variables.Then,the resultant nonlinear nature of flow model is treated numerically via Runge-Kutta scheme.The characteristics of various pertinent flow parameters on the velocity,temperature,streamlines and isotherms are discussed graphically.It is inspected that the Lorentz forces favors the rotational velocity and rotational parameter opposes it.Intensification in the nanofluids temperature is observed for volumetric fraction and thermal radiation parameter and dominating trend is noted for γ-aluminum nanofluid.Furthermore,for higher rotational parameter,reverse flow is investigated.To provoke the validity of the present work,comparison between current and literature results is presented which shows an excellent agreement.It is examined that rotation favors the velocity of the fluid and more radiative fluid enhances the fluid temperature.Moreover,it is inspected that upturns in volumetric fraction improves the thermal and electrical conductivities.展开更多
文摘Elastography-based liver stiffness measurement(LSM) is a non-invasive tool for estimating liver fibrosis but also provides an estimate for the severity of portal hypertension in patients with advanced chronic liver disease(ACLD). The presence of varices and especially of varices needing treatment(VNT) indicates distinct prognostic stages in patients with compensated ACLD(cACLD). The Baveno VI guidelines suggested a simple algorithm based on LSM < 20 kPa(by transient elastography, TE) and platelet count > 150 G/L for ruling-out VNT in patients with cACLD. These(and other) TE-based LSM cut-offs have been evaluated for VNT screening in different liver disease etiologies. Novel point shear-wave elastography(pSWE) and two-dimensional shear wave elastography(2D-SWE) methodologies for LSM have also been evaluated for their ability to screen for "any" varices and for VNT. Finally, the measurement of spleen stiffness(SSM) by elastography(mainly by pSWE and 2D-SWE) may represent another valuable screening tool for varices. Here, we summarize the current literature on elastography-based prediction of "any" varices and VNT. Finally,we have summarized the published LSM and SSM cut-offs in clinically useful scale cards.
文摘In this study, the essence and origin of the magnetic constant are discussed and a mechanism that allows real estimations of the magnetic constant based upon the vacuum density description is proposed. By considering the vacuum as a liquid with a measurable density and the electron as a vortex, hydrodynamic laws are applied to measure the diminished momentum of a rotating electron in a vacuum, thus obtaining a value similar to the experimentally derived value of the magnetic constant. A consequence of this description is that the magnetic constant can be expressed as the shear stress per unit time of the vacuum;this means that it is an observable vacuum parameter and not a fundamental constant.
文摘The present work aims at identifying Nb-Ta-, Zr-Hf-, REE-, Th-U-bearing two-mica granite from geological, geophysical cross-sections and mineral chemistry studies from three boreholes at G. El Sela shear zone. Microscopically, the three boreholes are composed mainly of two-mica granite. They are composed of K-feldspar, plagioclase, quartz, biotite and muscovite. Accessories are pyrite, zircon, fluorite, rutile, monazite with Th-U-mineralization identified by scanning electron microscope (SEM) and electron probe-microanalyses (EPMA). Chlorite, muscovite, sericite, kaolinite are secondary minerals. Geochemically, two-mica granite boreholes are A-type granites and peraluminous characteristics. They are enriched in large ion lithophile elements (LILE;Ba, Rb and Sr), high field strength elements (Y, Zr and Nb), and LREE but depleted in HREE with negative Eu anomaly. U-enrichment associated with chloritization, muscovitization, albitization, sericitization, kaolinization and argillization results from convective hydrothermal circulation of fluids through brittle structures along the ENE-WSW main shear zone. The ratios Nb/Ta (7.7 - 17.7) and Zr/Hf (16.9 - 26.4) are relatively enriched in the lighter isovalents Ta and Hf. The accessory minerals observed in the two-mica granites are represented by metallic sulfides (pyrite, arsenopyrite, chalcopyrite, galena and sphalerite), Nb-rutile, Hf-zircon, fluorite, monazite, columbite, betafite, thorite, phosphothorite, uranothorite, brannerite, uraninite, coffinite and pitchblende at G. El Sela shear zone. Uraninite with a low Th content indicates a hydrothermal origin of U-mineralization, Thorite, uranothorite, monazite and zircon is the main uranium bearing minerals of magmatic origin within the enclosing granite. The primary U-mineralization has been observed in two boreholes. In order to illustrate the geophysical signature of El Sela U-mineralization, the radiometric, magnetic, and VLF-EM data as well as radon concentration are included. The magnetic, electrical conductivity
基金The project supported by the National Natural Science Foundation of China (Nos. 10075047, 40336052)
文摘This article presents a study we have made of one class of coherent structures of the tripolar vortex. Considering the sheared flow and sheared magnetic field which are common in the thermonuclear plasma and space plasma, we have simulated the dynamics of the tripolar vortex. The results show that the tripolar vortex is largely stable in most cases, but a strongly sheared magnetic field will make the structure less stable, and lead it to decays into single vortices with the large space scale. These results are consistent with findings from former research about the dipolar vortex.
基金supported by National Natural Science Foundation of China with Nos.11305027,11322549 and 11675038National Magnetic Confinement Fusion Science Program of China with No.2014GB124000partly supported by the Fundamental Research Funds for the Central Universities with Grant No.DUT15YQ103
文摘Characteristics of the magnetic-island-induced ion temperature gradient （MITG） mode are studied through gyrofluid simulations in the slab geometry, focusing on the effects of Landau damping, equilibrium magnetic shear （EMS）, and pressure flattening. It is shown that the magnetic island may enhance the Landau damping of the system by inducing the radial magnetic field. Moreover, the radial eigenmode numbers of most MITG poloidal harmonics are increased by the magnetic island so that the MITG mode is destabilized in the low EMS regime. In addition, the pressure profile flattening effect inside a magnetic island hardly affects the growth of the whole MITG mode, while it has different local effects near the O-point and the X-point regions. In comparison with the non-zero-order perturbations, only the quasi-linear flattening effect due to the zonal pressure is the effective component to impact the growth rate of the mode.
基金the Key Project 'Multiple Scale Processes in Geospace Storms' of the National Natural Science Foundation of China (Grant No. 40390150) the Project of 49834040,and the Chinese Key Research Project (Grant No.G200000784).
文摘Magnetic reconnection at the high-latitude magnetopause is studied using 2.5-dimensional Hall-MHD simulation. Concentric flow vortices and magnetic islands appear when both Hall effect and sheared flow are considered. Plasma mixing across the magnetopause occurs in the presence of the flow vortices. Reconnected structure generated in the vicinity of the subsolar point changes its geometry with increasing flow shear while moving to high latitudes. In the presence of flow shear, with the Hall-MHD reconnection a higher reconnection rate than with the traditional MHD is obtained. The out-of-plane components of flow and magnetic field produced by the Hall current are redistributed under the action of the flow shear, which makes the plasma transport across the boundaries more complicated. The simulation results provide some help in understanding the dynamic processes at the high latitude magnetopause.
基金National Science Foundation of Shangong Province of China(No.ZR2016AM30)National Natural Science Foundation of China(No.11875290)Foundation of Shandong Province Higher Educational Science and Technology Program,China(No.J15LN15)
文摘The linear evolution of a resistive wall mode(RWM)with magnetic shears was analytically studied in a cylindrical geometry.The incompressible magnetohydrodynamic(MHD)equations were solved by the Fourier analysis method,and various equilibrium magnetic fields were considered.The shear in the magnetic field had an unstable effect on the linear evolution of the RWM.The linear growth rate increased obviously with increase of the magnetic shear rate for higher magnetic shears.Slow plasma rotation could stabilize the RWM with low magnetic shears,but the plasma rotation could not stabilize the RWM with high magnetic shears.The stabilizing effects of the wall conductivity on the RWM are more efficient for lager magnetic shear.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2018YFA0208403 and 2016YFA0200403)the National Natural Science Foundation of China(Grant Nos.51472057,11874129,91323304,and 11674387)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA09040101)the Baotou Rare Earth Research and Development Centre,Chinese Academy of Sciences(Grant No.GZR 2018001)
文摘In this work we report that after single-walled carbon nanotubes(SWNTs) are sheared with a pair of titanium scissors,the magnetization becomes larger than that of the corresponding pristine ones. The magnetization increases proportionally with the number of SWNTs with sheared ends, suggesting that there exist magnetic moments at the sheared ends of SWNTs.By using the coefficient of this linear relation, the average magnetic moment is estimated to be 41.5 ± 9.8 μB(Bohr magneton) per carbon atom in the edge state at temperature of 300.0 K, suggesting that ultrahigh magnetic fields can be produced. The dangling sigma and pi bonds of the carbon atoms at sheared ends play important roles in determining the unexpectedly high magnetic moments, which may have great potential applications.
基金Sponsored by the National Nature Science Foundation of China (11202102,11172140)
文摘The flow of the weak electrolyte solution can be controlled by Lorentz force achieved with the suitable magnetic and electric fields, and it has the advantages of vortex street suppression, drag reduction, lift enhancement and oscillatory suppression for the flow over a bluff body. The electro-magnetic control of vortex-induced vibration (VIV) of a circular cylinder in the shear flow was investigated numerically in the exponential-polar coordinates attached on the moving cylinder for Re=150. With the effect of background vorticity, the vortex street of VIV cylinder was composed of two parallel rows with an opposite sign of the vortices which inclines toward the lower side and the strength of upper vortex is larger than that of lower vortex. The lift force vibrated periodically with the effect of vortex shedding and the mean value was negative due to the background vorticity. The Lorentz force for controlling the VIV cylinder was classified into the field Lorentz force and the wall Lorentz force. The field Lorentz force suppresses the lift oscillation, and in turn, suppresses the VIV, whereas the wall Lorentz force increases the lift.
文摘This article investigates the colloidal study for water and ethylene glycol based nanofluids.The effects of Lorentz forces and thermal radiation are considered.The process of non-dimensionalities of governing equations is carried out successfully by means of similarity variables.Then,the resultant nonlinear nature of flow model is treated numerically via Runge-Kutta scheme.The characteristics of various pertinent flow parameters on the velocity,temperature,streamlines and isotherms are discussed graphically.It is inspected that the Lorentz forces favors the rotational velocity and rotational parameter opposes it.Intensification in the nanofluids temperature is observed for volumetric fraction and thermal radiation parameter and dominating trend is noted for γ-aluminum nanofluid.Furthermore,for higher rotational parameter,reverse flow is investigated.To provoke the validity of the present work,comparison between current and literature results is presented which shows an excellent agreement.It is examined that rotation favors the velocity of the fluid and more radiative fluid enhances the fluid temperature.Moreover,it is inspected that upturns in volumetric fraction improves the thermal and electrical conductivities.
