Smooth Transition from Shakura—Sunyaev Disc to Advection—Dominated Accretion Flow

We solve a set of basic equations describing black hole accretion flows using the standard Runge-kutta method and a bridging formula for the radiative cooling,and show that a smooth transition from a shakura-Sunyaev disc to an advection-dominated accretion flow is realizable for the high-viscosity case,without the need of involving any extra mechanism of energy transport.     

镉试剂;2B一平平加一sDs一双波长光度法测定微最锦的研究及应用

本文研究了在平平加一SDS混合型表面活性剂存在下,Cd(I)与Cadion 2$的显色反应,提出了一个高灵敏度测定镐的双波长分光光度法.Cd( I )-Cadion 2B一平平加一SDS配合物的最大吸收波长为506nm,试剂空白的最大吸收波长为G05nm,表观摩尔吸光系数为2.25x105L}mo1-l.cm-1, Cd( I)在。-11 }g/25m1范围内服从比耳定律.本法可用于电镀废水中微量锡的直接测定,所得结果在此浓度范围内与原子吸收法颇为吻合.测得回收率为93. 7-104 % .     

Characteristics of Double Gamma-Ray Bursts

Double gamma-ray bursts （DGRBs） have two well-separated sub-bursts in the main prompt emission and the typical time interval between them is in the hundreds of seconds. Among DGRBs, gamma-ray bursts （DGRBs） 110801A and 120716A are the ones with known redshifts. However, unlike GRB 110801A, we show that the two sub-bursts of GRB 120716A is severally similar to the short- and long-duration GRBs, thus it is difficult to explain the origin of GRB 120716A by the popular models on the central engine of GRBs. We suggest that some mechanisms of x-ray flares in GRBs, i.e., a post-merger millisecond pulsars or the jet precession in a black hole hyperaccretion system may produce the DGRB.     

Standing Rankine-Hugoniot Shocks in Black Hole Accretion Discs

We study the problem of standing shocks in viscous disc-like accretion flows around black holes. For the first time we parametrize such a flow with two physical constants, namely the specific angular momentum accreted by the black hole j and the energy quantity K. By providing the global dependence of shock formation in the j- K parameter space, we show that a significant parameter region can ensure solutions with Rankine-Hugoniot shocks; and that the possibilities of shock formation are the largest for inviscid flows, decreasing with increasing viscosity, and ceasing to exist for a strong enough viscosity. Our results support the view that the standing shock is an essential ingredient in black hole accretion discs and is a general phenomenon in astrophysics, and that there should be a continuous change from the properties of inviscid flows to those of viscous ones.     

Standing Shocks in Viscous Accretion Flows around Black Holes

We study the problem of standing shocks in viscous accretion flows around black holes. We parameterize such a flow with two physical constants, namely the specific angular momentum accreted by the black hole j and the energy quantity K. By providing the global dependence of shock formation in the j - K parameter space, we show that a significant parameter region can ensure solutions with shocks of different types, namely Rankine-Hugoniot shocks, isothermal shocks, and more realistically, mixed shocks.     

Constraints on Slim Accretion Discs

We show that when the gravitational force in the vertical direction is correctly calculated, the well-known S- shaped sequence of thermal equilibrium solutions can be constructed only for small radii of black hole accretion flows, such that slim accretion discs can possibly exist only in the inner regions of these flows.     

镉试剂2B—平平加—SDS—双波长光度法测定微量镉的研究及应用

本文研究了在平平加-SDS混合型表面活性剂存在下,Cd(Ⅱ)与Cadion 2B的显色反应,提出了一个高灵敏度测定镉的双波长分光光度法.Cd(Ⅱ)-Cadion 2B-平平加-SDS配合物的最大吸收波长为506nm,试剂空白的最大吸收波长为605nm,表观摩尔吸光系数为2.25×10~5L·mol~(-1)·cm~(-1),Cd(Ⅱ)在0—11此g/25ml范围内服从比耳定律.本法可用于电镀废水中微量镉的直接测定,所得结果在此浓度范围内与原子吸收法颇为吻合.测得回收率为98.7—104％.