About Dendrimers: Structure, Physical Properties, and Applications

We review the properties and behavior of 20 X-ray binaries that contain a dynamically-confirmed black hole, 17 of which are transient systems. During the past decade, many of these transien...

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X-Ray Properties of Black-Hole Binaries

Correlated variations in the line and continuum emission from active galactic nuclei (AGNs) can be used to determine the size and geometry of the broad emission-line regions (BLRs). We have spectro- photometrically monitored a well-de—ned sample of 28 Palomar-Green quasars in order to obtain mea- surements of their BLRs and to investigate the relationships between quasar luminosity, central black hole mass, and BLR size in AGNs. Spectrophotometry was obtained every 1¨4 months for 7.5 yr, yield- ing 20¨70 observing epochs per object. Both the continuum and emission-line —uxes of all of the quasars were observed to change during the duration of the observing program. Seventeen of the 28 objects were observed with adequate sampling independent observing epochs) to search for correlated variations (Z20 between the Balmer emission lines and the continuum —ux. For each of these 17 objects, a signi—cant correlation was observed, with the Balmer-line variations lagging those of the continuum by D100 days (rest frame). Our work increases the available luminosity range for studying the size-mass-luminosity relations in AGNs by 2 orders of magnitude and doubles the number of objects suitable for such studies. Combining our results with comparable published data available for Seyfert 1 galaxies, we —nd the BLR size scales with the rest-frame 5100 luminosity as L0.70B0.03. This determination of the scaling of the Ae size of the BLR as a function of luminosity is signi—cantly diUerent from those previously published and suggests that the eUective ionization parameter in AGNs may be a decreasing function of luminosity. We are also able to constrain, subject to our assumption that gravity dominates the motions of the BLR gas, the scaling relationship between the mass of the central black holes and the luminosity in AGNs. We —nd that the central mass scales with 5100 luminosity as M P L0.5B0.1. This is inconsistent with all Ae AGNs having optical luminosity that is a constant fraction of the Eddington luminosity. Subject headings: galaxies: activequasars: emission linesquasars: general

https://iopscience.iop.org/article/10.1086/308704/pdf

Reverberation Measurements for 17 Quasars and the Size-Mass-Luminosity Relations in Active Galactic Nuclei

We present improved black hole masses for 35 active galactic nuclei (AGNs) based on a complete and consistent reanalysis of broad emission-line reverberation-mapping data From objects with multiple line measurements, we find that the highest precision measure of the virial product cτΔV2/G, where τ is the emission-line lag relative to continuum variations and ΔV is the emission-line width, is obtained by using the cross-correlation function centroid (as opposed to the cross-correlation function peak) for the time delay and the line dispersion (as opposed to FWHM) for the line width and by measuring the line width in the variable part of the spectrum Accurate line-width measurement depends critically on avoiding contaminating features, in particular the narrow components of the emission lines We find that the precision (or random component of the error) of reverberation-based black hole mass measurements is typically around 30%, comparable to the precision attained in measurement of black hole masses in quiescent galaxies by gas or stellar dynamical methods Based on results presented in a companion paper by Onken et al, we provide a zero-point calibration for the reverberation-based black hole mass scale by using the relationship between black hole mass and host-galaxy bulge velocity dispersion The scatter around this relationship implies that the typical systematic uncertainties in reverberation-based black hole masses are smaller than a factor of 3 We present a preliminary version of a mass-luminosity relationship that is much better defined than any previous attempt Scatter about the mass-luminosity relationship for these AGNs appears to be real and could be correlated with either Eddington ratio or object inclination

/pdf/central-masses-and-broad-line-region-sizes-of-active-2q0abxk6re.pdf

Central masses and broad-line region sizes of active galactic nuclei. ii. a homogeneous analysis of a large reverberation-mapping database

Polymer brushes: surface-immobilized macromolecules

We assume the time-averaged structure of a macroion solution to be determined only by the repulsive screened Coulomb pair potential between finite macroions. The counter ions and solvent are treated as a uniform neutralizing background which determines the screening of the potential. We slove the Ornstein-Zernike equation in the mean spherical approximation to obtain closed analytic forms for the direct correlation function c(r) and the structure factor S(Q). In the zero charge limit, the Percus-Yevick hard sphere solution is recovered. As charge is added to the macroions at given volume fraction, the isothermal compressibility decreases and S(Q) shows increasing structure, eventually exhibiting solid-like behaviour. The results provide a useful model basis for studying interacting colloidal systems, and finite ion screened one component plasmas in general.

An analytic structure factor for macroion solutions

We present a general method of determining the structure and charge of globular ionic micelles, using neutron small-angle scattering. The micellar solutions may have any concentration within the micellar phase. The method is based in part on an analytic calculation of the interparticle correlations between monodisperse spherical micelles, and we discuss the theory in some detail to justify its application to polydisperse globular particles. Experimental results are presented for several cationic and anionic micellar systems.

Determination of micelle structure and charge by neutron small-angle scattering

The application of the specular reflection of neutrons to the study of surface and interfaces is described. The theoretical and experimental background to the technique is presented. A range of recent experimental results in surface chemistry, solid films and surface magnetism is discussed. In surface chemistry the results include adsorption of surfactants at the air-solution interface, insoluble monolayers and polymers at the air-liquid interface, soap films and adsorption at the liquid-solid and liquid-liquid interfaces. In solid films results on Langmuir-Blodgett films, hard carbon films, polymer films and some semiconductor layers are discussed. In surface magnetism experimental data which illustrate the nature of magnetism in magnetic multilayers and ferromagnetic films, and which describe flux penetration in superconductors, are presented.

https://iopscience.iop.org/article/10.1088/0953-8984/2/6/001/pdf

Jeffrey Penfold

Papers

An analytic structure factor for macroion solutions

Determination of micelle structure and charge by neutron small-angle scattering

The application of the specular reflection of neutrons to the study of surfaces and interfaces

Surfactant layers at the air/water interface: structure and composition.

Polymer/surfactant interactions at the air/water interface