Shielding effects

By using an effective, distance-dependent dielectric constant, the ability of bulk water to reduce electrostatic interactions can be mimicked without the presence of explicit solvent molecules. One disadvantage of aU vacuum simulations, corrected for shielding effects or not, is the fact that they cannot account for the ability of water molecules to form hydrogen bonds with charged and polar surface residues of a protein. As a result, adjacent polar side chains interact with each other and not with the solvent, thus introducing additional errors. 

The spectrum of 5-ethylthiothiazole compared to that of thiazole shows a slight deshielding effect on H-Cq (9 versus 9.1 ppm) and a slight shielding effect on H-C4 (7.93 versus 7.88 ppm) (270). 

Attenuation Reduction of the signal power of field strength as a function of distance through a material. Also refers to shielding effectiveness. 

Dual chamber test method Measures near field shielding effectiveness by indicating the signal attenuation caused by passage through test material. 

Schirm, m. screen shelter, shade umbrella parachute visor (of a cap) Bot.) umbel, -bild, n. screen image, schirmen, v.t. screen shelter protect. Schirm-gitter, n. Radio) screen grid, -gitter-rohre, /. screen id tube, -pflanze, /. umbelliferous plant, -wirkung, /. screening or shielding effect. 

The qualitative thermodynamic explanation of the shielding effect produced by the bound neutral water-soluble polymers was summarized by Andrade et al. [2] who studied the interaction of blood with polyethylene oxide (PEO) attached to the surfaces of solids. According to their concept, one possible component of the passivity may be the low interfacial free energy (ysl) of water-soluble polymers and their gels. As estimated by Matsunaga and Ikada [3], it is 3.7 and 3.1 mJ/m2 for cellulose and polyvinylalcohol whereas 52.6 and 41.9 mJ/m2 for polyethylene and Nylon 11, respectively. Ikada et al. [4] also found that adsorption of serum albumin increases dramatically with the increase of interfacial free energy of the polymer contacting the protein solution. 

Due to the shielding effect exerted by the carbohydrate framework (C-4 axial hydrogen at C-3), cyanide can more easily attack from the Si-face. 

The shielding effect of the vicinal phenyl substituent accounts for the favored attack of the cyanide from the opposite direction, giving rise to the (S)-diastereomers. However, it should be noted that imines of aliphatic aldehydes which bear an odd number of carbons in the main side chain surprisingly give (/ )-diastereomcrs, concluded from ORD data48. This opposite stereochemical course in the formation of these compounds has not been explained48. It might simply be due to crystallization of the (R)-diastereomer which continuously shifts the equilibrium (vide supra). 

Fig. 7-12 Comparing shielding effect of conductive coatings on a 1 /8 in. thick PC sheets...

The important action of electrostatic forces between a cationic model and an anionic polynucleotide is clearly shown in Fig. 7. The hypochromicity sharply decreased with the ionic strength of the solution, which indicates that the base-base interactions between A12 and Poly U supported by the electrostatic attractive forces are weakened by the shielding effects of added salts. 

Antifoulants or metal surface cleaners to reduce the risk of pitting corrosion and other forms of concentration cell corrosion initiated at the metal surface by shielding effects from inorganic deposits. These could also be called deposit control agents. 

In a concentrated solution, characterized by an effective medium viscosity r e "Hs, the hydrodynamic field decays much faster due to the shielding effect of the encountered polymer segments ... 

As well as being attracted to the nucleus, each electron in a many-electron atom is repelled by the other electrons present. As a result, it is less tightly bound to the nucleus than it would be if those other electrons were absent. We say that each electron is shielded from the full attraction of the nucleus by the other electrons in the atom. The shielding effectively reduces the pull of the nucleus on an electron. The effective nuclear charge, Z lle, experienced by the electron is always less than the actual nuclear charge, Ze, because the electron-electron repulsions work against the pull of the nucleus. A very approximate form of the energy of an electron in a many-electron atom is a version of Eq. 14b in which the true atomic number is replaced by the effective atomic number ... 

Evidence has been presented from F-nmr shielding effects in m- and p-substituted fluorobenzenes (10) that solvent interaction modifies the O/ values of a number of the substituents of Table V (specifically NMc2, NH2, NHCOMe, OMe, CH3SO, SF3, CF3SO, CF3, SO3ME, CN, CO2R, NO2 and MeCO). The indicated changes in Oj between hydrocarbon and weakly protonic solvents are... 

Ethylene-vinyl acetate Fetterman [37] reinforced compounded ethylene-vinyl acetate (EVA) copolymer by using short hbers and found that silane coupling agents were effective at establishing improved hber-matrix adhesion. Das et al. [38] prepared carbon fiber-filled conductive composites based on EVA and studied the electromagnetic interference shielding effectiveness of the composites. 

A FuUerene Core to Probe Dendritic Shielding Effects. 88... 

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