Non-polar portion

It has already been observed in the case of pure liquids such as substituted hydrocarbons that the surface tension was, if not completely defined by the non-polar portions of the molecule, at least not so markedly affected by substituent groups as we should anticipate if no orientation existed. Again, although vaporisation and condensation at a liquid surface such as water at high temperatures takes place with great speed, yet the life of a molecule on the surface is probably long enough to permit of such adjustment as orientation requires. Even more conclusive in favour of the hjq)othesis of at least partial orientation is the evidence derived from a consideration of the latent heats of evaporation and the... 

With non-polar minerals such as talc, mica and coal, the particle surfaces can interact with the non-polar portion of the molecules by van der Waals force. In this case, hydrocarbon portions can function as mineralophilic groups. Except in the case of depressants or some flocculants, the non-polar portions of long hydrocarbon chains in flotation agents possess only the framework formed from C-H groups with linking to polar hydrophilic and minerophilic groups [4]. 

When a mixture of sulfonate and sulfate is used as the collector, the order of depressability of the above reagents is (I) > (II) > (IV) > (III) > (X) > (VII) > (VI) > (V). This order shows that higher depression ability is possessed by those molecules which have more polar groups, higher activities of such groups and less non-polar portion. 

Surfactants are those chemicals whose molecules have two parts of widely differing polarity and solubility. The soaps, for example, have an ionizing salt head to the molecule and a long non-polar hydrocarbon tail . A different type are the polyoxyethylene ethers of dodecyl alcohol, e.g. Ci2H25 0 (CH2 CH2 0)6 H. These contain the non-polar dodecyl group (C12H25-), from dodecyl alcohol, at one end of the molecule and the successive polar ether linkages at the other. Whatever the formula or type, all surfactant molecules have in common these polar and non-polar portions. 

To the question of how the phosphatide molecules are orientated in the coacervate/aqueous medium boundary one is inclined to answer that the polar portion of the molecule will indeed be directed towards the aqueous medium, and consequently the non-polar portion towards the coacervatc side. In that case the bimolecular film is set on the two outer sides with polar groups. 

We have the feeling that it will be important in the study of the colloid chemistry of the colouring matters to lay emphasis on the correspondence with soap solutions. The aligning forces exerted on the dye molecules in solution are to be compared with the forces to which soap molecules are subject. Both kinds of molecule are anisodimensional, a strongly polar group is attached to a large non-polar portion. It is not surprising that correspondences are found in the solutions. ... 

XPS confirmed that loss of antistatic performance of PE films for packaging electronic parts was related to the formation of antistat crystallites [72]. In order to gain information about the mechanism of antistatic action Williams et al. [73] have analysed glyceryl monoesters in PP by means of XPS. The approximate sampling depths (3 X) were 20 A for 20° and 70 A for 80° relative to carbon electrons. As well-known, internal fatty acid ester antistats contain polar and non-polar portions. The general accepted mechanism for additive performance is migration to the polymer surface, where... 

Molecular sieves are available with a variety of pore sizes. A molecular sieve should be selected with a pore size that will admit H2S and water while preventing heavy hydrocarbons and aromatic compound.s from entering the pores. However, carbon dioxide molecules are about the same size as H2S molecules and present problems. Even thougli die COi is non-polar and will not bond to the active sites, the CO2 will entci the pores. Small quantities of CO2 will become trapped in the pores In this way small portions of CO2 are removed. More importantly, CO ih obstruct the access of H2S and water to active sites and decrease the eflectiveness ot the pores. Beds must be sized to remove all water and to pi ovitte for interference from other molecules in order to remove all H i.S. 

Ionophores are necessary since the lipid components of biological membranes tend to be orientated such that their polar groups face the membrane surfaces while the non-polar hydrocarbon portions occupy the membrane interior. The hydrophobic nature of the centre of the membrane thus acts as a barrier to the passage of ions such as sodium or potassium. 

Van der Waals forces, although very weak, operate in all adsorbent-adsorbate interactions, and result from short-range dipole-dipole, dipole-induced dipole, or induced dipole-induced dipole attractions. Although van der Waals interactions are forces acting universally, they assume particular importance in the adsorption of nonionic and non-polar molecules or portions of molecules on similar sites of the adsorbent molecule [17,159]. These forces are additive, and thus their contribution increases with the size of the molecule and with its capacity to adapt to the adsorbent surface. Van der Waals attractions have often been invoked in case of difficulties in explaining adsorption of an organic pollutant onto SPHS, but the experimental evidence has not always been convincing. 

Polarity of functional group The 0—H bond is very polar. As the number of carbon atoms in an alcohol becomes larger, the alkyl group s non-polar nature becomes more important than the polar 0—H bond. Therefore small alcohols are more polar than alcohols with large hydrocarbon portions. 

While most CA s of disaccharides have depended only on intrinsic characteristics of the molecule, experimental results depend strongly on the environment. By experiment, Kamide and Saito ( ) have shown that the degree of flexibility of cellulose and its derivatives is strongly dependent on the dielectric constant of the solvent as well as the exact type and degree of substitution. Since a substantial portion of the polymer flexibility depends on the extent of variability of the torsion angles at the intermonomer linkage, the dependence of polymer flexibility on type of solvent and substitution means that the disaccharide flexibility also should depend on those factors. Non-polar solvents allowed the molecules to have greater flexibility than did polar solvents (35). 

Thus the type of emulsion formed depends essentially on the relative cross-section areas of the non-polar and polar portions of... 

A portion (10.2 cm x 17.8 cm) of each RSP sample was sequentially extracted in a Soxhlet apparatus with cyclohexane, di-chloromethane and acetone, (8 hr. for each solvent) in the order given. A more complete extraction of the organic compounds present in particulate matter is achieved and a partial separation of the organic compounds into non-polar, moderately polar and polar fractions is obtained by this method. The volume of each extract was reduced to 10.0 ml using a rotary evaporator. The samples were then stored in a freezer at -15 C until further analysis. Weights of extracts were determined by weighing duplicate 100 yl aliquots of each, taken to dryness on a slide warmer (40 C), on a Cahn Electrobalance. 

Calcium in this case would coordinate with acyl oxygens from the polypeptide backbone of the protein, because of its unique amino acid sequences and potential conformations348). Non-polar peptides have been isolated from elastin which consists almost entirely of the three non-polar amino acids glycine, valine, and proline349). Portions of porcine tropoelastin have been partially sequenced350). Repeating tetra-, penta-, and hexapeptides have been observed. The tetrapeptide contains the sequence —Gly—Gly—L—Val—L—Pro— the pentapeptide —L—Val—L—Pro-... 

Method 2 (p-nitrobenzyl ester). To the residue are added 3 ml of ethanol and a 20-fold excess of 1 -p-nitrobenzyl-3-p-tolyltriazene [43]. The contents are mixed, loosely covered and heated at a gentle reflux for 1 h. The solution is cooled and an aliquot portion is subjected to chromatography. The derivatives are non-polar compared to the reagent and the parent fatty acid, and may be separated on silica gel with non-polar solvents such as hexane-diethyl ether. HPLC should also be useful with a system similar to that used for the benzyl esters. The limits of detection of the p-nitrobenzyl derivatives should be significantly lower than those of the benzyl esters. 

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