Using front face-pumped compact active mirror laser （CAMIL） structure, we have demonstrated an Yb：YAG/YAG composite ceramic disk laser with pumping wavelength at 970 nm. The laser has been operated in both continuo...Using front face-pumped compact active mirror laser （CAMIL） structure, we have demonstrated an Yb：YAG/YAG composite ceramic disk laser with pumping wavelength at 970 nm. The laser has been operated in both continuous-wave （CW） and Q-switching modes. Under CW operation, laser output power of 1.05 W with 2% transmission output coupler was achieved at the wavelength of 1031 nm. Q- switched laser output was gotten by using an acousto-optic Q-switch. The repetition rate ranged from 1 to 30 kHz and the pulse width varied from 166 to 700 ns.展开更多
The blood–brain barrier(BBB) and the blood–brain tumor barrier(BBTB) prevent drug and nano-drug delivery systems from entering the brain. However, ligand-mediated nano-drug delivery systems have significantly enhanc...The blood–brain barrier(BBB) and the blood–brain tumor barrier(BBTB) prevent drug and nano-drug delivery systems from entering the brain. However, ligand-mediated nano-drug delivery systems have significantly enhanced the therapeutic treatment of glioma. In this study we investigated the mechanism especially the integrity of liposomes and lipid disks while traversing the BBB and BBTB both in vitro and in vivo. Fluorophores(DiO, DiI and DiD) were loaded into liposomes and lipid disks to form F?rster resonance energy transfer(FRET) nano-drug delivery systems. Using brain capillary endothelial cells as a BBB model, we show that liposomes and disks are present in the cytoplasm as their intact forms and traverse the BBB with a ratio of 0.68‰ and 1.67‰, respectively. Using human umbilical vein endothelial cells as BBTB model, liposomes and disks remained intact and traversed the BBTB with a ratio of 2.31‰and 8.32‰ at 3 h. Ex vivo imaging and immunohistochemical results revealed that liposomes and disks could traverse the BBB and BBTB in vivo as intact forms. In conclusion, these observations explain in part the mechanism by which nano-drug delivery systems increase the therapeutic treatment of glioma.展开更多
OBJECTIVE:To investigate whether the Chinese massage system,Tuina,exerts analgesic effects in a rat model of chronic constriction injury(CCI)by remodeling the synaptic structure in the spinal cord dorsal horn(SCDH).ME...OBJECTIVE:To investigate whether the Chinese massage system,Tuina,exerts analgesic effects in a rat model of chronic constriction injury(CCI)by remodeling the synaptic structure in the spinal cord dorsal horn(SCDH).METHODS:Sixty-nine male Sprague–Dawley rats were randomly and evenly divided into the normal group,sham group,CCI group,CCI+Tuina group,CCI+MK-801[an N-methyl D-aspartate receptor subtype 2B(NR2B)antagonist]group,and CCI+MK-801+Tuina group.The neuropathic pain model was established using CCI with right sciatic nerve ligation.Tuina was administered 4 d after CCI surgery,using pressing manipulation for 10 min,once daily.Motor function was observed with the inclined plate test,and pain behaviors were observed by the Von Frey test and acetone spray test.At 19 d after surgery,the L3-L5 spinal cord segments were removed.Glutamate,interleukin 1β(IL-1β),and tumor necrosis factor-α(TNF-α)levels were detected by enzyme-linked immunosorbent assay.The protein expression levels of NR2B and postsynaptic density protein-95(PSD-95)were detected by Western blot,and the synaptic structure was observed by transmission electron microscopy(TEM).RESULTS:CCI reduced motor function and caused mechanical and cold allodynia in rats,increased glutamate concentration and TNF-αand IL-1βlevels,and increased expression of synapse-related proteins NR2B and PSD-95 in the SCDH.TEM revealed that the synaptic structure of SCDH neurons was altered.Most of these disease-induced changes were reversed by Tuina and intrathecal injection of MK-801(P<0.05 or<0.01).For the majority of experiments,no significant differences were found between the CCI+MK-801 and CCI+MK-801+Tuina groups.CONCLUSIONS:Chinese Tuina can alleviate pain by remodeling the synaptic structure,and NR2B and PSD-95 receptors in the SCDH may be among its targets.展开更多
The present study examines the thermal distribution of ternary nanofluid flow amid two spinning disks influenced by electric and magnetic fields. Keeping in view the shape of the particles, the electrically conducting...The present study examines the thermal distribution of ternary nanofluid flow amid two spinning disks influenced by electric and magnetic fields. Keeping in view the shape of the particles, the electrically conducting ternary nanofluid is analyzed with variable thermophysical features. Three types of nanoparticles namely Copper, Aluminum Oxide, and Graphene with spherical, cylindrical, and platelet shapes are taken respectively and are immersed in a (50-50)% ratio of water and ethylene glycol mixture which acts as a base fluid. The anticipated problem is addressed by employing a reliable and user-friendly numerical bvp4c built-in collocation scheme. This solution is then showcased through illustrations and tables. Strengthening the radiation results in an enhanced heat transfer rate. Radial and azimuthal velocities once rotation of disks is enhanced. The key findings provide a strong theoretical background in photovoltaic cells, solar collectors, radiators, solar water heaters, and many other applications.展开更多
The velocity, pressure and temperature distributions of the flow in the gap between hydro-viscous drive friction disks are the key parameters in the design of hydro-viscous drive and angular velocity controller. In th...The velocity, pressure and temperature distributions of the flow in the gap between hydro-viscous drive friction disks are the key parameters in the design of hydro-viscous drive and angular velocity controller. In the previous works dealing with the flow in the gap between disks in hydro-viscous drive, few authors considered the effect of Coriolis force on the flow. The object of this work is to investigate the flow with consideration of the effects of centrifugal force, Coriolis force and variable viscosity. A simplified mathematical model based on steady and laminar flow is presented. An approximate solution to the simplified mathematical model is obtained by using the iteration method assuming that the fluid viscosity remains constant. Then the model considering the effect of variable viscosity is solved by means of computational fluid dynamics code FLUENT. Numerical results of the flow are obtained. It is found that radial velocity profile diverges from the ideal parabolic curve due to inertial forces and tangential velocity profile is nonlinear due to Coriolis force, and pressure has two possible solution branches. In addition, it is found that variable viscosity plays an important role on pressure profiles which are significantly different from those of fluid with constant viscosity. The experimental device designed for this work consists of two disks, and one of them is fixed. Experimental pressure and temperature of the flow within test rig are obtained. It is shown that the trend of numerical results is in agreement with that of experimental ones. The research provides a theoretical foundation for hydro-viscous drive design.展开更多
The archival Rossi X-ray Timing Explorer (RXTE) Proportional Counter Array (PCA) observations of HZ Her/Her X-1 are analyzed here. The time periods for Anomalous Low States are refined. The 35-day X-ray lightcurve of ...The archival Rossi X-ray Timing Explorer (RXTE) Proportional Counter Array (PCA) observations of HZ Her/Her X-1 are analyzed here. The time periods for Anomalous Low States are refined. The 35-day X-ray lightcurve of Her X-1 is produced using 35-day phases determined with RXTE All-Sky Monitor (ASM) and Swift Burst Alert Telescope (BAT) data, with adjustments based on the RXTE/PCA data. As a result, we constructed the best-phased 35-day lightcurve of Her X-1 with the highest sensitivity. The RXTE/PCA data are separated into 8 different substates of the 35-day cycle: Main High (MH) turn-on, MH, MH decline, Low State (LS) 1, Short High (SH) turn-on, SH, SH decline, and LS2. Orbital lightcurves are created for each substate, and they are compared. Eclipse data are extracted for each substate to determine the changes in eclipse shape with 35-day phase. A scattering corona model is fit to the eclipses for the different 35-day substates: this shows that the corona is present with similar intensity at all 35-day phases. We search for previously reported dips without absorption but find none.展开更多
The disk around MWC 480 has shown multiple substructures in both dust and gas observations,possibly suggesting ongoing planet formation in situ.In this paper,we explore the gas kinematics of the MWC 480 disk by analyz...The disk around MWC 480 has shown multiple substructures in both dust and gas observations,possibly suggesting ongoing planet formation in situ.In this paper,we explore the gas kinematics of the MWC 480 disk by analyzing the archival Atacama Large Millimeter/submillimeter Array observations of^(12)CO(J=2-1),^(13)CO(J=2-1),and C^(18)O(J=2-1).By modeling the line-of-sight velocities,inferred from the Doppler shifts of the emission lines,we are able to decompose the three-dimensional(3D)velocity field of the disk into rotational,radial,and vertical components.Further analysis reveals the presence of large-scale gas flows in the(r,z)plane.Notably,we identify potential meridional flows across various heights as traced by all three CO isotopologues in the 80–120 au region,possibly associated with ongoing planet formation activities in this region.Moreover,we find upward flows near 200 au for all three CO isotopologues,which may point to the presence of disk winds.展开更多
A possible quasi-periodic oscillation(QPO) at frequency 7.045 × 10^(-5) Hz is found in the narrow-line Seyfert 1galaxy Mrk 142 in the data of XMM-Newton collected on 2020 April 11.We find that the QPO signal is s...A possible quasi-periodic oscillation(QPO) at frequency 7.045 × 10^(-5) Hz is found in the narrow-line Seyfert 1galaxy Mrk 142 in the data of XMM-Newton collected on 2020 April 11.We find that the QPO signal is statistically significantly larger than the 5σ level and highly coherent with quality factor Q > 5 at the 0.3–10 keV band by using the method of the Lomb–Scargle Periodogram,the Weighted Wavelet Z-transform and the REDFIT.We analyze the data in 0.3–0.6 keV,0.6–1 keV,1–3 keV and 3–10 keV energy bands,and find obvious QPO signals at 0.3–0.6 keV and 1–3 keV bands.We then analyze the time-average spectra and time variability at the QPO frequency of 7.045 × 10^(-5) Hz,and use a model to fit them.We find that the QPO signal mainly comes from the X-ray hot corona.展开更多
We present a comprehensive analysis of the 2021 outburst of MAXI J1803–298 utilizing observations of the Insight-Hard X-ray Modulation Telescope(Insight-HXMT)spanning from the low hard state to the high soft state.Wi...We present a comprehensive analysis of the 2021 outburst of MAXI J1803–298 utilizing observations of the Insight-Hard X-ray Modulation Telescope(Insight-HXMT)spanning from the low hard state to the high soft state.Within the Insight-HXMT data set,compared to the previous work,we identify a more prolonged presence of typeC quasi-periodic oscillations(QPOs)with centroid frequencies ranging from~0.16 to 6.3 Hz,which present correlations with the hardness ratio and the photon index of the Comptonized component.For QPO frequencies less than~2 Hz,the QPO phase lags are hard(photons of 10–19 keV arrive later than those of 1–4 keV),while at higher frequencies,the lags become soft at and above~4 Hz.Furthermore,the spectra in all Insight-HXMT observations consist of a multi-color blackbody component and a Comptonized component,as commonly observed in classical black hole X-ray binaries.We analyze state transitions and the evolution of accretion geometry in this work.The fitted inner disk radius increases abnormally during the low hard state,hypothesized to result from the corona condensing onto the inner disk.Additionally,two significant drops in flux are observed during the soft intermediate state,maybe implying changes in the corona/jet and the disk,respectively.展开更多
The steady, laminar, incompressible and two dimensional micropolar flow between two porous disks was investigated using optimal homotopy asymptotic method(OHAM) and fourth order Runge–Kutta numerical method. Comparis...The steady, laminar, incompressible and two dimensional micropolar flow between two porous disks was investigated using optimal homotopy asymptotic method(OHAM) and fourth order Runge–Kutta numerical method. Comparison between OHAM and numerical method shows that OHAM is an exact and high efficient method for solving these kinds of problems. The results are presented to study the velocity and rotation profiles for different physical parameters such as Reynolds number, vortex viscosity parameter, spin gradient viscosity and microinertia density parameter. As an important outcome, the magnitude of the microrotation increases with an increase in the values of injection velocity while it decreases by increasing the values of suction velocity.展开更多
Infrared(IR)spectral energy distribution(SED)is the major tracer of protoplanetary disks.It was recently proposed to use the near-to-mid IR(or K-24)SED slopeαdefined between 2 and 24μm as a potential quantitative tr...Infrared(IR)spectral energy distribution(SED)is the major tracer of protoplanetary disks.It was recently proposed to use the near-to-mid IR(or K-24)SED slopeαdefined between 2 and 24μm as a potential quantitative tracer of disk age.We critically examine the viability of this idea and confront it with additional statistics of IR luminosities and SED shapes.We point out that,because the statistical properties of most of the complicated physical factors involved in disk evolution are still poorly understood in a quantitative sense,the only viable way is to assume them to be random so that an idealized“average disk”can be defined,which allows theαhistogram to trace its age.We confirm that the statistics of the zeroth order(luminosity),first order(slopeα),and second order characteristics(concavity)of the observed K-24 SEDs indeed carry useful information upon the evolutionary processes of the“average disk”.We also stress that intrinsic diversities in K-24 SED shapes and luminosities are always large at the level of individual stars so that the application of the evolutionary path of the“average disk”to individual stars must be done with care.The data of most curves in plots are provided on GitHub(Disk-age package https://github.com/starage/disk-age/).展开更多
Numerical solution is presented for the two- dimensional flow of a micropolar fluid between two porous coaxial disks of different permeability for a range of Reynolds number Re （-300≤ Re 〈 0） and permeability para...Numerical solution is presented for the two- dimensional flow of a micropolar fluid between two porous coaxial disks of different permeability for a range of Reynolds number Re （-300≤ Re 〈 0） and permeability parameter A （1.0≤A ≤2.0）. The main flow is superimposed by the injection at the surfaces of the two disks. Von Karman＇s similarity transformations are used to reduce the governing equations of motion to a set of non-linear coupled ordinary differential equations （ODEs） in dimensionless form. An algorithm based on the finite difference method is employed to solve these ODEs and Richardson＇s extrapolation is used to obtain higher order accuracy. The results indicate that the parameters Re and A have a strong influence on the velocity and microrotation profiles, shear stresses at the disks and the position of the viscous/shear layer. The micropolar material constants cl, c2, c3 have profound effect on microrotation as compared to their effect on streamwise and axial velocity profiles. The results of micropolar fluids are compared with the results for Newtonian fluids.展开更多
The dipole-dipole interaction model is used to calculate the angular dependence of lateral and levitation forces on a small permanent magnet and a cylindrical superconductor in the Meissner state lying laterally off t...The dipole-dipole interaction model is used to calculate the angular dependence of lateral and levitation forces on a small permanent magnet and a cylindrical superconductor in the Meissner state lying laterally off the symmetric axis of the cylinder. Under the assumption that the lateral displacement of the magnet is small compared with the physical dimensions of the system, we obtain analytical expressions for the lateral and levitation forces as functions of geometrical parameters of the superconductor as well as the height, the lateral displacement and the orientation of magnetic moment of the magnet. The effect of thickness and radius of the superconductor on the levitation force is similar to that for a symmetric magnet/superconducting cylinder system, but within the range of lateral displacement. The splitting in the levitation force increases with the increasing angle of orientation of the magnetic moment of the magnet. For a given lateral displacement of the magnet, the lateral force vanishes when the magnetic moment is perpendicular to the surface of the superconductor and has a maximum value when the moment is parallel to the surface. For a given orientation of the magnetic moment, the lateral force has a linear relationship with the lateral displacement. The stability of the magnet above the superconducting cylinder is discussed in detail.展开更多
In the present paper, we deal with the complex Szasz-Durrmeyer operators and study Voronovskaja type results with quantitative estimates for these operators attached to analytic functions of exponential growth on comp...In the present paper, we deal with the complex Szasz-Durrmeyer operators and study Voronovskaja type results with quantitative estimates for these operators attached to analytic functions of exponential growth on compact disks. Also, the exact order of approximation is found.展开更多
The importance of controlled temperature during the four-days co-cultivation period was evaluated under the most physiologically relevant conditions for Agrobacterium tumefaciens-mediated transformation of tobacco (Ni...The importance of controlled temperature during the four-days co-cultivation period was evaluated under the most physiologically relevant conditions for Agrobacterium tumefaciens-mediated transformation of tobacco (Nicotiana tabacum L. cv. Xanthi (nn, Smith)) leaf disks. We compared the effect of temperatures ranging from 15°C, 18°C, 20°C, 22°C to 25°C on the stable expression of β-glucuronidase (GUS) activity of 14 days old hygromycin-selected leaf disks, and on the increase in the fresh weight yield of 28 days old kanamycin-selected calli. The highest average of GUS activity was obtained at 20°C among the five temperatures tested although the difference between the 18°C and 20°C treatment was not statistically significant. The GUS activity at 15°C was statistically lower than those at 18°C and 20°C. The GUS activity in 22°C treatment was an intermediate between the highest (18/20°C) and second highest averages (15°C), and was not statistically significantly different. The lowest average of GUS activity was observed at 25°C. The highest increase in the plate average of fresh weight yield was obtained at 20°C among the five temperature tested. The 20°C treatment was statistically significantly better than the 15°C and 18°C treatments. The 20°C co-cultivation treatment resulted in the higher FW yield than 22°C and 25°C even though the differences were not statistically significant. In conclusion, low co-cultivation temperature at 20°C resulted in the reproducible maximum increase in both the fresh weight yield and stable expression of GUS activity after transformation of tobacco leaf disks.展开更多
This is a general review Oil the observations and physics of black hole X-ray binaries and microquasars, with the emphasize on recent developments in the high energy regime. The focus is put on understanding the accre...This is a general review Oil the observations and physics of black hole X-ray binaries and microquasars, with the emphasize on recent developments in the high energy regime. The focus is put on understanding the accretion flows and measuring the parameters of black holes in them. It includes mainly two parts： i） Brief review of several recent review article on this subject; ii） Further development on several topics, including black hole spin measurements, hot accretion flows, corona formation, state transitions and thermal stability of standard think disk. This is thus not a regular bottom-up approach, which I feel not necessary at this stage. Major effort is made in making and incorporating from many sources useful plots and illustrations, in order to make this article more comprehensible to non-expert readers. In the end I attempt to make a unification scheme on the accretion-outflow （wind/jet） connections of all types of aecreting BHs of all accretion rates and all BH mass scales, and finally provide a brief outlook.展开更多
Let f be an entire function of finite lower order μ and order λ If the zeros of ff'-1 are attracted to q(<+∞) rays,then λmust be finite.Moreover,we have(i)λ≤1/2,when q=1.(ii)The magnitude of acute angle o...Let f be an entire function of finite lower order μ and order λ If the zeros of ff'-1 are attracted to q(<+∞) rays,then λmust be finite.Moreover,we have(i)λ≤1/2,when q=1.(ii)The magnitude of acute angle of these two rays is exactly equal toπ/λ,when q=2 and μ>1 (iii)There are at least two rays such that the magnitude of acute angle between them does not exceed π/λ,when q≥2展开更多
基金supported by the Shanghai Important Foundation Project under Grant No.07DJ14001.
文摘Using front face-pumped compact active mirror laser （CAMIL） structure, we have demonstrated an Yb：YAG/YAG composite ceramic disk laser with pumping wavelength at 970 nm. The laser has been operated in both continuous-wave （CW） and Q-switching modes. Under CW operation, laser output power of 1.05 W with 2% transmission output coupler was achieved at the wavelength of 1031 nm. Q- switched laser output was gotten by using an acousto-optic Q-switch. The repetition rate ranged from 1 to 30 kHz and the pulse width varied from 166 to 700 ns.
基金supported by China Postdoctoral Science Foundation Grant (No.2017M611464)National Basic Research Program of China (973 Program, No. 2013CB932500)+2 种基金National Natural Science Foundation of China (Nos. 81773657, 81690263 and 81473149)Shanghai Education Commission Major Project (2017-01-07-00-07E00052)Shanghai International Science and Technology Cooperation Project (No. 16430723800)
文摘The blood–brain barrier(BBB) and the blood–brain tumor barrier(BBTB) prevent drug and nano-drug delivery systems from entering the brain. However, ligand-mediated nano-drug delivery systems have significantly enhanced the therapeutic treatment of glioma. In this study we investigated the mechanism especially the integrity of liposomes and lipid disks while traversing the BBB and BBTB both in vitro and in vivo. Fluorophores(DiO, DiI and DiD) were loaded into liposomes and lipid disks to form F?rster resonance energy transfer(FRET) nano-drug delivery systems. Using brain capillary endothelial cells as a BBB model, we show that liposomes and disks are present in the cytoplasm as their intact forms and traverse the BBB with a ratio of 0.68‰ and 1.67‰, respectively. Using human umbilical vein endothelial cells as BBTB model, liposomes and disks remained intact and traversed the BBTB with a ratio of 2.31‰and 8.32‰ at 3 h. Ex vivo imaging and immunohistochemical results revealed that liposomes and disks could traverse the BBB and BBTB in vivo as intact forms. In conclusion, these observations explain in part the mechanism by which nano-drug delivery systems increase the therapeutic treatment of glioma.
基金Natural Science Foundation-funded Project:Study on the Mechanism of Tuina and Tuina in Regulating the Synaptic Plasticity of Spinal Dorsal Horn in Lumbar Disc Herniation Based on LncRNA-HOTAIR/miR-219 Mediated NMDAR Pathway(No.82174523)Natural Science Foundation of Fujian Province:Study on the Mechanism of Tuina Regulating the Synaptic Plasticity of Spinal Dorsal Horn in Lumbar Disc Herniation based on NMDAR-CAMK2-CREB Pathway(No.2020J01757)+2 种基金Study on Analgesic Mechanism of Tuina on Neuropathic Pain in Spinal Dorsal Horn/ACC Brain Region based on PKA-NMDA-NR2B Pathway(No.2020J01758)Fujian Health Science and Technology Program:Study on the Analgesic Mechanism of Tuina Manipulation On Lumbar Disc Herniation from the Efficacy of miR-219/NR2B Mediated Synaptic Transmission(No.2020GGA070)Effects of Tuina Point Press on AMPA/NMDA Receptor Scaffold Protein and Synaptic Plasticity in Spinal Dorsal Horn of Rats with Neuropathic Pain(No.2020CXA052)。
文摘OBJECTIVE:To investigate whether the Chinese massage system,Tuina,exerts analgesic effects in a rat model of chronic constriction injury(CCI)by remodeling the synaptic structure in the spinal cord dorsal horn(SCDH).METHODS:Sixty-nine male Sprague–Dawley rats were randomly and evenly divided into the normal group,sham group,CCI group,CCI+Tuina group,CCI+MK-801[an N-methyl D-aspartate receptor subtype 2B(NR2B)antagonist]group,and CCI+MK-801+Tuina group.The neuropathic pain model was established using CCI with right sciatic nerve ligation.Tuina was administered 4 d after CCI surgery,using pressing manipulation for 10 min,once daily.Motor function was observed with the inclined plate test,and pain behaviors were observed by the Von Frey test and acetone spray test.At 19 d after surgery,the L3-L5 spinal cord segments were removed.Glutamate,interleukin 1β(IL-1β),and tumor necrosis factor-α(TNF-α)levels were detected by enzyme-linked immunosorbent assay.The protein expression levels of NR2B and postsynaptic density protein-95(PSD-95)were detected by Western blot,and the synaptic structure was observed by transmission electron microscopy(TEM).RESULTS:CCI reduced motor function and caused mechanical and cold allodynia in rats,increased glutamate concentration and TNF-αand IL-1βlevels,and increased expression of synapse-related proteins NR2B and PSD-95 in the SCDH.TEM revealed that the synaptic structure of SCDH neurons was altered.Most of these disease-induced changes were reversed by Tuina and intrathecal injection of MK-801(P<0.05 or<0.01).For the majority of experiments,no significant differences were found between the CCI+MK-801 and CCI+MK-801+Tuina groups.CONCLUSIONS:Chinese Tuina can alleviate pain by remodeling the synaptic structure,and NR2B and PSD-95 receptors in the SCDH may be among its targets.
文摘The present study examines the thermal distribution of ternary nanofluid flow amid two spinning disks influenced by electric and magnetic fields. Keeping in view the shape of the particles, the electrically conducting ternary nanofluid is analyzed with variable thermophysical features. Three types of nanoparticles namely Copper, Aluminum Oxide, and Graphene with spherical, cylindrical, and platelet shapes are taken respectively and are immersed in a (50-50)% ratio of water and ethylene glycol mixture which acts as a base fluid. The anticipated problem is addressed by employing a reliable and user-friendly numerical bvp4c built-in collocation scheme. This solution is then showcased through illustrations and tables. Strengthening the radiation results in an enhanced heat transfer rate. Radial and azimuthal velocities once rotation of disks is enhanced. The key findings provide a strong theoretical background in photovoltaic cells, solar collectors, radiators, solar water heaters, and many other applications.
基金supported by National Natural Science Foundation of China (Grant No. 50475106)
文摘The velocity, pressure and temperature distributions of the flow in the gap between hydro-viscous drive friction disks are the key parameters in the design of hydro-viscous drive and angular velocity controller. In the previous works dealing with the flow in the gap between disks in hydro-viscous drive, few authors considered the effect of Coriolis force on the flow. The object of this work is to investigate the flow with consideration of the effects of centrifugal force, Coriolis force and variable viscosity. A simplified mathematical model based on steady and laminar flow is presented. An approximate solution to the simplified mathematical model is obtained by using the iteration method assuming that the fluid viscosity remains constant. Then the model considering the effect of variable viscosity is solved by means of computational fluid dynamics code FLUENT. Numerical results of the flow are obtained. It is found that radial velocity profile diverges from the ideal parabolic curve due to inertial forces and tangential velocity profile is nonlinear due to Coriolis force, and pressure has two possible solution branches. In addition, it is found that variable viscosity plays an important role on pressure profiles which are significantly different from those of fluid with constant viscosity. The experimental device designed for this work consists of two disks, and one of them is fixed. Experimental pressure and temperature of the flow within test rig are obtained. It is shown that the trend of numerical results is in agreement with that of experimental ones. The research provides a theoretical foundation for hydro-viscous drive design.
文摘The archival Rossi X-ray Timing Explorer (RXTE) Proportional Counter Array (PCA) observations of HZ Her/Her X-1 are analyzed here. The time periods for Anomalous Low States are refined. The 35-day X-ray lightcurve of Her X-1 is produced using 35-day phases determined with RXTE All-Sky Monitor (ASM) and Swift Burst Alert Telescope (BAT) data, with adjustments based on the RXTE/PCA data. As a result, we constructed the best-phased 35-day lightcurve of Her X-1 with the highest sensitivity. The RXTE/PCA data are separated into 8 different substates of the 35-day cycle: Main High (MH) turn-on, MH, MH decline, Low State (LS) 1, Short High (SH) turn-on, SH, SH decline, and LS2. Orbital lightcurves are created for each substate, and they are compared. Eclipse data are extracted for each substate to determine the changes in eclipse shape with 35-day phase. A scattering corona model is fit to the eclipses for the different 35-day substates: this shows that the corona is present with similar intensity at all 35-day phases. We search for previously reported dips without absorption but find none.
基金supported by the National Key Research and Development Program of China grant No.2021YFC2203001National Natural Science Foundation of China(NSFC,Grant Nos.12322301 and 12275021)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences,grant No.XDB2300000the Interdiscipline Research Funds of Beijing Normal University。
文摘The disk around MWC 480 has shown multiple substructures in both dust and gas observations,possibly suggesting ongoing planet formation in situ.In this paper,we explore the gas kinematics of the MWC 480 disk by analyzing the archival Atacama Large Millimeter/submillimeter Array observations of^(12)CO(J=2-1),^(13)CO(J=2-1),and C^(18)O(J=2-1).By modeling the line-of-sight velocities,inferred from the Doppler shifts of the emission lines,we are able to decompose the three-dimensional(3D)velocity field of the disk into rotational,radial,and vertical components.Further analysis reveals the presence of large-scale gas flows in the(r,z)plane.Notably,we identify potential meridional flows across various heights as traced by all three CO isotopologues in the 80–120 au region,possibly associated with ongoing planet formation activities in this region.Moreover,we find upward flows near 200 au for all three CO isotopologues,which may point to the presence of disk winds.
基金financial supports from the Science Foundation of Department of Education of Yunnan Province (2024J0935)。
文摘A possible quasi-periodic oscillation(QPO) at frequency 7.045 × 10^(-5) Hz is found in the narrow-line Seyfert 1galaxy Mrk 142 in the data of XMM-Newton collected on 2020 April 11.We find that the QPO signal is statistically significantly larger than the 5σ level and highly coherent with quality factor Q > 5 at the 0.3–10 keV band by using the method of the Lomb–Scargle Periodogram,the Weighted Wavelet Z-transform and the REDFIT.We analyze the data in 0.3–0.6 keV,0.6–1 keV,1–3 keV and 3–10 keV energy bands,and find obvious QPO signals at 0.3–0.6 keV and 1–3 keV bands.We then analyze the time-average spectra and time variability at the QPO frequency of 7.045 × 10^(-5) Hz,and use a model to fit them.We find that the QPO signal mainly comes from the X-ray hot corona.
基金supported by the National Key R&D Program of China(2021YFA0718500)the National Natural Science Foundation of China(NSFC,Grant No.12133007)partially supported by the International Partnership Program of Chinese Academy of Sciences(Grant No.113111KYSB20190020)。
文摘We present a comprehensive analysis of the 2021 outburst of MAXI J1803–298 utilizing observations of the Insight-Hard X-ray Modulation Telescope(Insight-HXMT)spanning from the low hard state to the high soft state.Within the Insight-HXMT data set,compared to the previous work,we identify a more prolonged presence of typeC quasi-periodic oscillations(QPOs)with centroid frequencies ranging from~0.16 to 6.3 Hz,which present correlations with the hardness ratio and the photon index of the Comptonized component.For QPO frequencies less than~2 Hz,the QPO phase lags are hard(photons of 10–19 keV arrive later than those of 1–4 keV),while at higher frequencies,the lags become soft at and above~4 Hz.Furthermore,the spectra in all Insight-HXMT observations consist of a multi-color blackbody component and a Comptonized component,as commonly observed in classical black hole X-ray binaries.We analyze state transitions and the evolution of accretion geometry in this work.The fitted inner disk radius increases abnormally during the low hard state,hypothesized to result from the corona condensing onto the inner disk.Additionally,two significant drops in flux are observed during the soft intermediate state,maybe implying changes in the corona/jet and the disk,respectively.
文摘The steady, laminar, incompressible and two dimensional micropolar flow between two porous disks was investigated using optimal homotopy asymptotic method(OHAM) and fourth order Runge–Kutta numerical method. Comparison between OHAM and numerical method shows that OHAM is an exact and high efficient method for solving these kinds of problems. The results are presented to study the velocity and rotation profiles for different physical parameters such as Reynolds number, vortex viscosity parameter, spin gradient viscosity and microinertia density parameter. As an important outcome, the magnitude of the microrotation increases with an increase in the values of injection velocity while it decreases by increasing the values of suction velocity.
基金supported by the Natural Science Foundation of Yunnan Province(No.202201 BC070003)supported by the ANID FONDECYT Postdoctoral program No.3220029+2 种基金support by ANID,—Millennium Science Initiative Program—NCN19_171sponsored(in part)by the Chinese Academy of Sciences(CAS)the CAS South America Center for Astronomy(CASSACA)in Santiago,Chile.
文摘Infrared(IR)spectral energy distribution(SED)is the major tracer of protoplanetary disks.It was recently proposed to use the near-to-mid IR(or K-24)SED slopeαdefined between 2 and 24μm as a potential quantitative tracer of disk age.We critically examine the viability of this idea and confront it with additional statistics of IR luminosities and SED shapes.We point out that,because the statistical properties of most of the complicated physical factors involved in disk evolution are still poorly understood in a quantitative sense,the only viable way is to assume them to be random so that an idealized“average disk”can be defined,which allows theαhistogram to trace its age.We confirm that the statistics of the zeroth order(luminosity),first order(slopeα),and second order characteristics(concavity)of the observed K-24 SEDs indeed carry useful information upon the evolutionary processes of the“average disk”.We also stress that intrinsic diversities in K-24 SED shapes and luminosities are always large at the level of individual stars so that the application of the evolutionary path of the“average disk”to individual stars must be done with care.The data of most curves in plots are provided on GitHub(Disk-age package https://github.com/starage/disk-age/).
文摘Numerical solution is presented for the two- dimensional flow of a micropolar fluid between two porous coaxial disks of different permeability for a range of Reynolds number Re （-300≤ Re 〈 0） and permeability parameter A （1.0≤A ≤2.0）. The main flow is superimposed by the injection at the surfaces of the two disks. Von Karman＇s similarity transformations are used to reduce the governing equations of motion to a set of non-linear coupled ordinary differential equations （ODEs） in dimensionless form. An algorithm based on the finite difference method is employed to solve these ODEs and Richardson＇s extrapolation is used to obtain higher order accuracy. The results indicate that the parameters Re and A have a strong influence on the velocity and microrotation profiles, shear stresses at the disks and the position of the viscous/shear layer. The micropolar material constants cl, c2, c3 have profound effect on microrotation as compared to their effect on streamwise and axial velocity profiles. The results of micropolar fluids are compared with the results for Newtonian fluids.
文摘The dipole-dipole interaction model is used to calculate the angular dependence of lateral and levitation forces on a small permanent magnet and a cylindrical superconductor in the Meissner state lying laterally off the symmetric axis of the cylinder. Under the assumption that the lateral displacement of the magnet is small compared with the physical dimensions of the system, we obtain analytical expressions for the lateral and levitation forces as functions of geometrical parameters of the superconductor as well as the height, the lateral displacement and the orientation of magnetic moment of the magnet. The effect of thickness and radius of the superconductor on the levitation force is similar to that for a symmetric magnet/superconducting cylinder system, but within the range of lateral displacement. The splitting in the levitation force increases with the increasing angle of orientation of the magnetic moment of the magnet. For a given lateral displacement of the magnet, the lateral force vanishes when the magnetic moment is perpendicular to the surface of the superconductor and has a maximum value when the moment is parallel to the surface. For a given orientation of the magnetic moment, the lateral force has a linear relationship with the lateral displacement. The stability of the magnet above the superconducting cylinder is discussed in detail.
文摘In the present paper, we deal with the complex Szasz-Durrmeyer operators and study Voronovskaja type results with quantitative estimates for these operators attached to analytic functions of exponential growth on compact disks. Also, the exact order of approximation is found.
文摘The importance of controlled temperature during the four-days co-cultivation period was evaluated under the most physiologically relevant conditions for Agrobacterium tumefaciens-mediated transformation of tobacco (Nicotiana tabacum L. cv. Xanthi (nn, Smith)) leaf disks. We compared the effect of temperatures ranging from 15°C, 18°C, 20°C, 22°C to 25°C on the stable expression of β-glucuronidase (GUS) activity of 14 days old hygromycin-selected leaf disks, and on the increase in the fresh weight yield of 28 days old kanamycin-selected calli. The highest average of GUS activity was obtained at 20°C among the five temperatures tested although the difference between the 18°C and 20°C treatment was not statistically significant. The GUS activity at 15°C was statistically lower than those at 18°C and 20°C. The GUS activity in 22°C treatment was an intermediate between the highest (18/20°C) and second highest averages (15°C), and was not statistically significantly different. The lowest average of GUS activity was observed at 25°C. The highest increase in the plate average of fresh weight yield was obtained at 20°C among the five temperature tested. The 20°C treatment was statistically significantly better than the 15°C and 18°C treatments. The 20°C co-cultivation treatment resulted in the higher FW yield than 22°C and 25°C even though the differences were not statistically significant. In conclusion, low co-cultivation temperature at 20°C resulted in the reproducible maximum increase in both the fresh weight yield and stable expression of GUS activity after transformation of tobacco leaf disks.
基金Acknowledgements I appreciate inputs from Profs. Lijun Gou, Weimin Gu, Lixin Li, Bifang Liu, Dingxiong Wang, Wenfei Yu, Feng Yuan, and Shu Zhang. The editors of this book are thanked for inviting me to write this article, as well as their patience, persistency, proof reading it, and offering comments and suggestions to improve it in the end. This work was partially supported with funding the 973 Program of China under grant 2009CB824800, by the National Natural Science Foundation of China under grant Nos. 11133002 and 10725313 and the Qianren start-up grant 292012312Dl117210.
文摘This is a general review Oil the observations and physics of black hole X-ray binaries and microquasars, with the emphasize on recent developments in the high energy regime. The focus is put on understanding the accretion flows and measuring the parameters of black holes in them. It includes mainly two parts： i） Brief review of several recent review article on this subject; ii） Further development on several topics, including black hole spin measurements, hot accretion flows, corona formation, state transitions and thermal stability of standard think disk. This is thus not a regular bottom-up approach, which I feel not necessary at this stage. Major effort is made in making and incorporating from many sources useful plots and illustrations, in order to make this article more comprehensible to non-expert readers. In the end I attempt to make a unification scheme on the accretion-outflow （wind/jet） connections of all types of aecreting BHs of all accretion rates and all BH mass scales, and finally provide a brief outlook.
基金Project supported by the Croucher FoundationTianyuan Foundation+1 种基金partially supported by a U.P.G.C.grantHong Kong
文摘Let f be an entire function of finite lower order μ and order λ If the zeros of ff'-1 are attracted to q(<+∞) rays,then λmust be finite.Moreover,we have(i)λ≤1/2,when q=1.(ii)The magnitude of acute angle of these two rays is exactly equal toπ/λ,when q=2 and μ>1 (iii)There are at least two rays such that the magnitude of acute angle between them does not exceed π/λ,when q≥2
