Paper refining effect

The use of computer simulations to study internal motions and thermodynamic properties is receiving increased attention. One important use of the method is to provide a more fundamental understanding of the molecular information contained in various kinds of experiments on these complex systems. In the first part of this paper we review recent work in our laboratory concerned with the use of computer simulations for the interpretation of experimental probes of molecular structure and dynamics of proteins and nucleic acids. The interplay between computer simulations and three experimental techniques is emphasized (1) nuclear magnetic resonance relaxation spectroscopy, (2) refinement of macro-molecular x-ray structures, and (3) vibrational spectroscopy. The treatment of solvent effects in biopolymer simulations is a difficult problem. It is not possible to study systematically the effect of solvent conditions, e.g. added salt concentration, on biopolymer properties by means of simulations alone. In the last part of the paper we review a more analytical approach we have developed to study polyelectrolyte properties of solvated biopolymers. The results are compared with computer simulations. 

Danforth DN (1986) Effect of refining parameters on paper properties. Proceedings of the International Conference on New Technologies in Refining, 2, PIRA, Birmingham, England, UK... 

The chemical and biological effects of ultrasound were first reported by Loomis more than 50 years ago (4). Within fifteen years of the Loomis papers, widespread industrial applications of ultrasound included welding, soldering, dispersion, emulsification, disinfection, refining, cleaning, extraction, flotation of minerals and the degassing of liquids (5),(6). The use of ultrasound within the chemical community, however, was sporadic. With the recent advent of inexpensive and reliable sources of ultrasound, there has been a resurgence of interest in the chemical applications of ultrasound. 

It is often necessary to increase tensile and other strength properties in paper by chemical means rather than mechanically via the refining process. This is usually the case when the other effects of refining, such as the decreases in opacity and air permeability, are not desired. 

Combination of the Hantzsch ester mediated transfer hydrogenation together with chlorine (116) or fluorine (117) electrophiles allows for the formal addition of HCl or HF aaoss a double bond in a catalytic asymmetric manner (Scheme 48) [178], Within this paper the reactions were further refined by the use of two cycle-specific secondary amines which effectively operated independently within the same reaction mixture. Impressively, this allowed access to either diastereoisomer of the product depending upon the absolute configuration of the catalyst used in the second step of the sequence. 

In aircraft jet fuels, for example, especially those for aircraft of the supersonic type, the chief problem so far encountered has been thermal stability prior to combustion. The fuel must be used as a cooling agent, and the resultant exposure to heat accelerates the formation of gum and sediment. These cause plugging of filters and fuel nozzles, and lacquering of heat-exchanger surfaces. Research to date has indicated that some additives are effective in improving jet-fuel stability (52), especially if the fuel has first been rigorously refined, but these additives are not combustion improvers in the sense discussed in this paper. 

The effect of polymer concentration on [M]e has also been shown in the study of Tobolsky et al. (35). Unfortunately, their experimental technique was not sufficiently refined, and the wide scatter of experimental points prevented quantitative deductions from their data. Comment is necessary with respect to one statement made in their paper. The authors assumed that the "true value of [M]e could be derived by linear extrapolation from the experimental [M]e s, obtained at high polymer concentrations, up to the point of intersection with the line [M]e= [M]0. However, this extrapolation is not valid because, as has been shown by Vrancken et al. (13), the results depend on the concentration of living ends. The proper determination of the true [M]e requires studies at low concentrations of living ends, as was done by Worsfold and Bywater (12) and by McCormick (11). 

Refinement papers should also mention any evidence that the protein is affected by crystallization. Packing effects may be evident in the model itself. For example, packing may induce slight differences between what are otherwise... 

Insufficient information is given in the original papers to enable these models to be re-created, and in order to investigate the effect of starting model each authors published structure was used as a starting point for the refinements performed here. 

Sulfur species are found in ambient air in most parts of North America and in most industrial countries. Their sources include natural emissions (biogenic and volcanic), smelting of ores and other industrial refining processes, and combustion of sulfurbearing fuels. This paper will focus on the combustion sources in the United States and some of the effects of their sulfur emissions. The environmental effects of sulfur in the environment have been of interest for many years and much of the information presented here has been drawn from the various conference proceedings and assessment documents that have been published in recent years (1-11). When specific references are not listed in the text, the information represents a consensus from these various sources. 

---