The Use of Cationic Agents to Increase the Efficiency of Titanium Dioxide in Paper

Handsheets were made with a bleached sulfite pulp, titanium dioxide and cationic agents. The optical properties of these sheets were studied in order to determine and compare the efficiency of the titanium dioxide retained. The cationic agents used in this study were a quaternary ammonium salt, a polyamide, cationic starches made with these two chemicals, and a commercial cationic starch. When the optical properties of handsheets made from these substances were compared, it was found that the quaternary ammonium salt gave the highest opacity but the lowest retention. The polyamide gave lower opacities but higher retentions. The cationic starches made from these cationic chemicals showed slightly lower opacities than the cationic chemicals by themselves but they gave much higher retentions. The commercial cationic starch gave intermediate retention but lower opacity. It was concluded that the quaternary ammonium salt gave the best dispersion of the titanium dioxide but gave the lowest cationic charge to the pigment. The polymide gave a slightly poorer dispersion but gave a much higher charge to the pigment. The cationic starches gave the best retention through a combination of mechanical and physio-chemical retention, but did not disperse the pigment too well

The Application of Zeta Potential for the Effective Retention of Titanium Dioxide in Chemically Modified Systems

This study was done to determine how to obtain maximum effective filler retention in a fiber and titanium dioxide system. Retention of fillers in a fibrous system is greatly influenced through the use of high molecular weight polymers. It was found that by using cationic and anionic polymers in the same system, a synergistic effect results which yields a higher effective retention than if either polymers were used along. Furthermore, by precisely controlling the amounts of each polymer so as to obtain the isoelectric point in zeta potential; the peak effective retention is reached

Increasing efficiency of switching type regulator circuits Patent

Switching series regulator with gating control networ

Symmetries, Hopf fibrations and supercritical elliptic problems

We consider the semilinear elliptic boundary value problem $$-\Delta u=\left\vert u\right\vert ^{p-2}u\text{ in }\Omega,\text{\quad }u=0\text{ on }\partial\Omega,$$ in a bounded smooth domain $\Omega$ of $\mathbb{R}^{N}$ for supercritical exponents $p>\frac{2N}{N-2}.$ Until recently, only few existence results were known. An approach which has been successfully applied to study this problem, consists in reducing it to a more general critical or subcritical problem, either by considering rotational symmetries, or by means of maps which preserve the Laplace operator, or by a combination of both. The aim of this paper is to illustrate this approach by presenting a selection of recent results where it is used to establish existence and multiplicity or to study the concentration behavior of solutions at supercritical exponents

Experimental Procedure for the Determination of Cavity Parameters

A new experimental procedure for the determination of cavity parameters is described. The procedure follows the basic steps described by Slater. In this method one measures the frequencies at which the voltage standing wave ratio at the input to the cavity reaches a predetermined value. The knowledge of these frequencies coupled with a determination of the state of coupling to the cavity yields the necessary information. An exposition of some pertinent theoretical points is followed by a detailed description of the experimental procedure

Alternating sign multibump solutions of nonlinear elliptic equations in expanding tubular domains

Let $\Gamma$ denote a smooth simple curve in $\mathbb{R}^{N}$, $N\geq2$, possibly with boundary. Let $\Omega_{R}$ be the open normal tubular neighborhood of radius 1 of the expanded curve $R\Gamma:=\{Rx\mid x\in \Gamma\smallsetminus\partial\Gamma\}$. Consider the superlinear problem $-\Delta u+\lambda u=f(u)$ on the domains $\Omega_{R}$, as $R\rightarrow \infty$, with homogeneous Dirichlet boundary condition. We prove the existence of multibump solutions with bumps lined up along $R\Gamma$ with alternating signs. The function $f$ is superlinear at 0 and at $\infty$, but it is not assumed to be odd. If the boundary of the curve is nonempty our results give examples of contractible domains in which the problem has multiple sign changing solutions

Using a GIS for Real Estate Market Analysis: The Problem of Spatially Aggregated Data

Many databases used for real estate market analysis are not available at the address level. For example, information on employment and unemployment may be available only for labor market areas; and Census data is typically tabulated for blocks or higher levels of spatial aggregation. A Geographic Information System (GIS) associates these spatially aggregated data with the geographical center of the area. This poses special problems when we use a GIS to evaluate linkages between supply and demand. This article presents some solutions to this problem; methods that are relatively easy to implement on a GIS are emphasized. A GIS can be used to calculate a theoretical average travel distance to the population in the geographical area. We propose ways to determine when these theoretical distances are inadequate approximations; and we provide alternatives for these situations.

Ribosomal small subunit sequence diversity of Scutellospora within single spores and roots of bluebell from a woodland community.

Roots of bluebell (Hyacinthoides nonscripta) were sampled from a woodland in Yorkshire,UK and spores of an arbuscular mycorrhizal fungus Scutellospora sp., were obtained from the surrounding soil. Partial small subunit (SSU) ribosomal RNA sequences were amplified from both roots and spores using either the universal forward primer SS38 or the Glomales-specific primer VANS1, with the reverse Gigasporaceaespecific primer VAGIGA. Amplified products were cloned and sequenced. Both spores and roots yielded sequences related to those known from fungi within the Glomales,with up to four distinct SSU sequences obtained from individual spores. The VANS1 primer-binding site varied considerably in sequence and only a subset of Scutellospora sequences were amplified when the VANS1 primer was used. In addition to glomalean sequences, a number of different sequences, apparently from ascomycetes, were obtained from both root and spore samples