Latexes description

Chemically related database searches can be used to estabhsh concepts and patentable ideas. For instance, searches have identified researchers using particular monomers in a potentially patentable latex formulation found precedents for a polymeric emulsifier summarized pubHcations of people being considered as consultants, expert witnesses, employees or speakers to an industrial group and provided market description information for a new pigment manufacturing firm to identify target markets. 

Latexes are usually copolymer systems of two or more monomers, and their total solids content, including polymers, emulsifiers, stabilizers etc. is 40-50% by mass. Most commercially available polymer latexes are based on elastomeric and thermoplastic polymers which form continuous polymer films when dried [88]. The major types of latexes include styrene-butadiene rubber (SBR), ethylene vinyl acetate (EVA), polyacrylic ester (PAE) and epoxy resin (EP) which are available both as emulsions and redispersible powders. They are widely used for bridge deck overlays and patching, as adhesives, and integral waterproofers. A brief description of the main types in current use is as follows [87]. 

Water-based barrier dressings are attractive for application to injured tissue because of the biocompatibility between water and tissue. The concept of a water-based dressing initially consisted of latex-type particles of polymer suspended in an aqueous emulsion. The emulsion would be liquid applied to the tissue, water would evaporate and the particles would coalesce to form a continuous film. The rate of evaporation of water is slow compared to solvents as ethanol that was recognized to be a limitation to application time (time to place on the tissue and harden). The following description of miniemulsions (miniEP) involves a batch type... 

The usual description of these different polymerization processes suggests that all produce stable latexes and various hypotheses have been advanced to explain the stability of these latexes to such factors as added electrolyte, mechanical shear and freezing and thawing. In the literature, there is little mention of the fact that many of these polymerizations produce varying amounts of coagulum, i.e., polymer recovered in a form other than that of a stable latex. This coagulum is produced in all sizes of polymerization reactors, ranging from the smallest laboratory... 

For this description of PCS, it is evident that, for mono-disperse systems, the technique can provide an absolute measurement of hydrodynamic size knowledge of the density or refractive index of the particles is not required, and no calibration or correction is needed. With the advent of digital correlators and microprocessors, PCS has also become a very fast and precise technique. Recent studies of latex using PCS include adsorbed layers (8), particle sizes (16), surface characterization (17) and aggregation (181- ... 

For many years, antigen-antibody reactions have been studied by agglutination techniques using red cells or "latex particles which were coated with antigen or antibody. In this case, particles are regarded as a labeled marker. Descriptions of several methods that have been devised for detecting agglutination follow. 

Of the 17 billion lb of butadiene consumed in 1999, almost two thirds went into the production of elastomers (styrene-butadiene latex rubber (SBR), polybutadiene, nitrile, and polychloroprene). Adiponitrile, ABS resins, styrene-butadiene latex, styrene block copolymers, and other smaller polymer uses accounted for the remainder. The largest single use was for styrene-butadiene copolymers (SBR and latex). Most of it was made by an emulsion process using a free-radical initiator and a styrene-butadiene ratio of about 1 3. More detailed description of the rubber and polymer used can be found in Chapters 16 and 15. 

A hydrophobic mismatch between a membrane protein and the surrounding lipids may create a lateral force that would pull membrane proteins together. A general theoretical description of this force, referred to as a lateral capillary force, has been presented by Kralchevsky and co-workers (Kralchevsky, 1997 Kralchevsky and Nagayama, 2000). Although experimental verification of this force for membrane proteins in a bilayer has not been demonstrated, the force can be observed in larger systems, such as 1.7 fim latex beads at an air/water interface, and would be expected to operate on membrane proteins (Kralchevsky, 1997). 

In what follows, the word particle will be used to describe the source of the scattering. The word will encompass rigid structures such as latex spheres as well as macromolecules such as linear polymer chains. The particle will be viewed as a collection of smaller components each of which scatters light so that the total scattering from a particle will be written as a sum of scattered waves from the components. Such an approach permits the convenient calculation of angular dependence of scattering as well as the description of internal dynamics of linear polymer chains. 

From this qualitative description of latex particles we can immediately recognize the origins of three basic forces that have to be considered in understanding the behavior of dispersions in both aqueous and nonaqueous media. These can be summarized as... 

In 1937, Balls et al. [4] purified one of the proteolytic fractions and called their crystalline enzyme papain. This was an unfortunate choice, since the name papain is also used for the crude papaya latex containing multiple enzymes. In 1939, Lineweaver and Balls published a refinement of the isolation method, and they also reported the presence in the papaya latex of another proteinase with a higher ratio of milk-clotting to hemoglobin-digesting activity than papain [5], In 1941 Jansen and Balls presented a description of a second proteolytic enzyme [6]... 

Despite the difficulties of theoretical approaches of polyelectrolytes, and especially of amphiphilic polyelectrolytes, work on protein/polymer systems is now mature enough to offer interesting opportunities to compare experimental results and models of colloid/polyelectrolyte. Biophysical approaches can in principle lead to a structural description of these colloids at an unprecedented level of detail. As compared to micelles or latex, the major... 

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Two herbal specimens of P. rhoeas have been studied (34) that do not differ morphologically from the typical P. rhoeas. One of the specimens is typical, with yellow latex, and it corresponds to Kuntze s description (10,42) of the taxon P. rhoeas var. chelidonioides O. Ktze., while the other has a white latex, turning pink in air. The composition of the tertiary fraction, where rhoeadine (389) and aporheine (115) are the dominant alkaloids in approximately equal amounts, characterizes the chemical type, which forms a transition between the typical P. rhoeas and P. dubium. In contrast to other populations of P. rhoeas, the... 

Since a meaningful analysis of latex particles requires measurements down to smallest q-values, a detailed description of an optimized small-angle camera together with the discussion of experimental problems of SAXS will be given. Also, we shall discuss the subsequent treatment of data and the steps necessary to extract the structural information from the SAXS-intensities. Section 4 is devoted to a discussion of the experimental results obtained in recent investigations. 

Besides a description of instruments, the following section will also contain a discussion of the treatment of data. This includes the removal of various contributions to the signal stemming from the suspension medium water and from the density fluctuations of the solid polymer in the latex particles. 

In the following, a description of an improved Kratky-camera [73] will be discussed together with an extended discussion of the treatment of data. This device is capable of measuring latex particles up to a diameter of 200 nm and reaches the q-range provided by SAXS-cameras which work in point collimation and use synchrotron radiation (cf. below [73]). 

Models begin conceptually for example, the concept that a blood vessel behaves as a fluid-filled pipe. Concepts may be developed into physical models, for example, using a latex tube to describe a blood vessel, upon which experiments are performed. Often, concepts are realized as mathematical models, whereby the concept is described by physical laws, transformed into a set of mathematical equations, and solved via computer. Simulations, distinct from models, are descriptions that mimic the physiological system. The quantitative nature of physiological models allows them to be employed as components of systems for the study of physiological control, illustrated in several of this section s chapters. 

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