Backbone neutral

Although some nanofiltration membranes are based on cellulose acetate, most are based on interfacial composite membranes. The preparation procedure used to form these membranes can result in acid groups attached to the polymeric backbone. Neutral solutes such as lactose, sucrose and raffinose are not affected by the presence of charged groups and the membrane rejection increases in proportion to solute size. Nanofiltration membranes with molecular weight cut-offs to neutral solutes between 150 and 1500 dalton are produced. Typical rejection curves for low molecular weight solutes by two representative membranes are shown in Figure 5.13 [35],... 

Okonogi TM, Alley SC, Harwood EA, Hopkins PB, Robinson BH (2002) Phosphate backbone neutralization increases duplex DNA flexibility a model for protein binding. Proc Natl Acad Sci USA 99(7) 4156-4160... 

ICPs and their derivatives can exist in several redox states oxidized or p-doped state, where electrons are removed from the polymer backbone neutral or undoped states are typically insulating or semiconducting and reduced or n-doped state... 

Telechelic Ionomers. Low molecular weight polymers terminated by acid groups have been treated with metal bases to give ionomers in which the cations can be considered as connecting links in the backbones (67—71). The viscoelastic behavior of concentrated solutions has been linked to the neutralizing cation. 

A waterborne system for container coatings was developed based on a graft copolymerization of an advanced epoxy resin and an acryHc (52). The acryhc-vinyl monomers are grafted onto preformed epoxy resins in the presence of a free-radical initiator grafting occurs mainly at the methylene group of the aHphatic backbone on the epoxy resin. The polymeric product is a mixture of methacrylic acid—styrene copolymer, soHd epoxy resin, and graft copolymer of the unsaturated monomers onto the epoxy resin backbone. It is dispersible in water upon neutralization with an amine before cure with an amino—formaldehyde resin. 

It has been observed that the best neutral cation carriers have the synclinal arrangement of binding atoms in the backbone (see 7.2). Syntheses of both an aliphatic and aromatic ligand are shown below in Eqs. (7.12) and (7.13). 

SynChropak GPC supports are bonded with y-glycidoxypropylsilane by a proprietary process that results in a thin, neutral hydrophilic layer that totally covers the silanol sites of the silica. The silica backbone prevents the supports from swelling. 

Why should the cores of most globular and membrane proteins consist almost entirely of a-helices and /3-sheets The reason is that the highly polar N—H and C=0 moieties of the peptide backbone must be neutralized in the hydrophobic core of the protein. The extensively H-bonded nature of a-helices and /3-sheets is ideal for this purpose, and these structures effectively stabilize the polar groups of the peptide backbone in the protein core. 

A complete set of intermolecular potential functions has been developed for use in computer simulations of proteins in their native environment. Parameters have been reported for 25 peptide residues as well as the common neutral and charged terminal groups. The potential functions have the simple Coulomb plus Lennard-Jones form and are compatible with the widely used models for water, TIP4P, TIP3P and SPC. The parameters were obtained and tested primarily in conjunction with Monte Carlo statistical mechanics simulations of 36 pure organic liquids and numerous aqueous solutions of organic ions representative of subunits in the side chains and backbones of proteins... 

In summary, all the transitions expected for the neutral states of a model system for conjugated polymers, the m-LPPP, were observed and described and all of these transitions also show clearly resolved vibronic replicas due to coupling to vibronic modes of the backbone. 

In contrast to the former Plantago CHX [55], the gel-forming CHX from psyllium (Plantago ovata) husks [54] was found to be a neutral, highly branched arabinoxylan with the (1 4)-j8-D-xylopyranose backbone substituted at position 2 with single Xylp units and at position 3 with the trisaccharide moiety (7). 

Arabinogalactans (AGs) are widely spread throughout the plant kingdom. Many edible and inedible plants are rich sources of these polysaccharides. AGs occur in two structurally different forms described as type I and type II, associated with the pectin cell-wall component by physical bonds and some of them are covalently linked to the complex pectin molecule as neutral side chains. Commercial pectins always contain AG 10-15%). AG of type I has a linear (1 4)-y0-o-Galp backbone, bearing 20-40% of of-L-Ara/ residues (1 5)-linked in short chains, in general at position 3. It is commonly found in pectins from citrus, apple and potato [6]. Recently, this AG type has been isolated from the skin of Opuntia ficus indica pear fruits [372]. 

Ionic polymers are a special class of polymeric materials having a hydrocarbon backbone containing pendant acid groups. These are then neutralized partially or fully to form salts. lonomeric TPEs are a class of ionic polymers in which properties of vulcanized rubber are combined with the ease of processing of thermoplastics. These polymers contain up to 10 mol% of ionic group. These ionomeric TPEs are typically prepared by copolymerization of a functionalized monomer with an olefinic unsamrated monomer or direct functionalization of a preformed polymer [68-71]. The methods of preparation of various ionomeric TPEs are discussed below. 

Liposomes are members of a family of vesicular structures which can vary widely in their physicochemical properties. Basically, a liposome is built of one or more lipid bilayers surrounding an aqueous core. The backbone of the bilayer consists of phospholipids the major phospholipid is usually phosphatidylcholine (PC), a neutral lipid. Size, number of bilayers, bilayer charge, and bilayer rigidity are critical parameters controlling the fate of liposomes in vitro and in vivo. Dependent on the preparation procedure unilamellar or multilamellar vesicles can be produced. The diameter of these vesicles can range from 25 nm up to 50 ym—a 2000-fold size difference. 

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