Fractionation references

First, the tar acids were removed from the naphtha fractions of light oils and, in the case of CVR tars, carboHc oil. The oils were then mixed with 25—35% sulfuric acid. After separation of the sulfates, the aqueous solution was diluted with water and the resinous material skimmed off. The diluted sulfate solution was boiled to expel any neutral oils, dried by the addition of soHd caustic soda or a2eotropically with ben2ene, and fractionated to yield pyridine, 2-methylpyridine (a-picoline), and a fraction referred to as 90/140 bases, which consisted mainly of 3- and 4-methylpyridines and 2,6-dimethylpyridine (2,6-lutidine). Higher boiling fractions were termed 90/160 and 90/180 bases because 90% of the product distilled at 160 and 180°C, respectively. 

Historical data on similar vessels and fractionation towers can best be used by correlating the costs of this equipment vs. weight. Many methods can be found in the literature for estimating the weight and costs of vessels and fractionators (References 8. 9, 10, and 11). Make sure the estimated weight is complete including skirt, ladders and platfonns, special internals, nozzles, and manholes. 

For comparison, we applied also a simplified LCAO-DFT method to get the conductivity by means of the Kubo-Greenwood formula. This method is a hybrid between ab initio and empirical methods and is described in detail in Ref. [12]. It allows a faster computation of the electronic properties and the consideration of larger supercells than the Car-Parrinello method. Within this scheme it is also possible to split the total DOS into fractions referring to the sodium and tin atoms, respectively, i.e. to get the partial densities-of-states. 

Fig, 3.47 Four additional dynamical measures for the system defined in figure 3.46-c N = 12, Ng = 50 and K = T16. The zero state fraction refers to the fraction of initial states So —t 0. 

It should be stressed that the observed critical strain-rate for bond fracture (sf) in the case of a polydisperse fraction refers to the longest chain present in the sample. This quantity is significantly different from the critical strain-rate (r ) defined with respect to an average molecular mass whose value could be determined only after careful consideration of the degradation kinetics. 

Fig. 2.6 The main components of a typical weakly reducing primeval atmosphere as a function of the altitude above the Earth s surface. The mole fraction refers to the mixing ratio of the atmospheric mixture at an assumed surface pressure of one atmosphere. After Kasting (1993)... 

Bitumen contains a solvent-soluble fraction referred to as maltenes, and an insoluble fraction called asphaltenes. The word bitumen is in some cases also used to indicate the residue of the distillation of petroleum. 

Biorefinery includes fractionation for separation of primary refinery products. The fractionation refers to the conversion of wood into its constituent components (cellulose, hemicelluloses and lignin). Processes include steam explosion, aqueous separation and hot water systems. Commercial products of biomass fractionation include levulinic acid, xylitol and alcohols. Figure 3.3 shows the fractionation of wood and chemicals from wood. 

An approach to studying transition states in enzyme-catalyzed reactions using solvent isotope effects. In this treatment, very useful in isotope effect experiments, the relative rates of contributing steps in a multistep reaction are grouped into a fraction referred to as the commitment factor ... 

Total Liquid (C5+) Yield. Product molecules with carbon numbers of five and higher can be combined in a fraction referred to as "05+" liquid product. This fraction includes the pentanes and all of the product boiling below the recycle cut point. The examples in Table II show that the more acidic catalyst produces less product in the C5+ fraction, more butanes and propane, and less product in the jet fuel boiling range than does the catalyst with higher hydrogenation activity. 

The disilane fraction refers to a fraction boiling over the range of about 150°-l 60° C which is obtained by fractionation of the higher boiling fraction of methylchlorosilanes produced by the so-called direct synthesis (141, 214). It is composed mainly of 1,1,2-trichlorotrimethyldisilane and 1,1,2,2-tetrachlorodimethyldisilane, somewhat contaminated by siloxanes (6, 22, 27, 114,125,126, 134). 

The density, p, is noted for each maceral fraction, reference 14. 

Recently Heremans demonstrated mucopolysaccharides in urine after zone electrophoresis by means of an Alcian blue-acid fuchsin staining technique (HI).3 Applied in our laboratory to a curtain after a run of serum, two fractions, references -)- 86.30 and - - 86.12, were demonstrated but do not seem to be regular components of serum, at least not in that high concentration (Fig. 62c). 

Another common component in natural waters is the poorly characterized fraction referred to as dissolved organic carbon (DOC). As a mixture of compounds, there is no data on the reactions of either e aq or H-. The reaction of DOC with OH has been evaluated by Westerhoff et al. [42], and earlier by S. Peyton (Illinois Department of Energy and Natural Resources, Champaign, IL, personal communication). Because of the varied nature of DOC in various waters, it is likely that each source may have slightly... 

Figure 9 Geminate recombination after photolysis of MbCO ( ) and microperoxidase-CO ( ). The survival fraction refers to the population that remains unbound after photolysis. The population was determined by measuring the IR absorbance at frequencies corresponding to the peak of the bound CO stretch. (Adapted from Ref. 67.)...

Is the shaving-recycle technique useful in preparing pure fractions Refer to your data. 

By the use of different modes of liquid chromatography it is possible to separate polymers selectively with respect to hydrodynamic volume (molar mass), chemical composition or functionality. Using these techniques and combining them with each other or with a selective detector, two-dimensional information on different aspects of molecular heterogeneity can be obtained. If, for example, two different chromatographic techniques are combined in a cross-fractionation mode, information on CCD and MMD can be obtained. Literally, the term chromatographic cross-fractionation refers to any combination of chromato-... 

Fig. 2. Number of papers published on FFF. Source Field-flow fractionation references web site update 14.10.1998 (see Sect. 6)...

Second, the overall tar vaporization processes (positions of the vaporization curves in Fig. I) is determined by the chemical con sition of the tar. The comparison between tobacco tar (solid squares) and its hexane phase partitioned fraction (referred as HP tobacco tar solid circles) indicates clearly (his important effect of chemical con iosition and functional groups, Note that the hexane phase partitioned fraction represents the less polar fraction of tobacco tar obtained by partitioning tar species from methanol solution into a hexane phase. 

Entries under a formula heading consist of the formula, in bold-faced type the name as it has been used in the subject index, in lightface roman type—that part of the entry in this type is the exact equivalent of the formula given occasionally a modifying phrase or word in italics which represents that part of the compound indexed not represented in the formula, as "Na salt or di-HCl and the column-fraction reference to the abstract proper. 

Heterogeneity is a generic quality of polysaccharides All characteristics occur as distributions and may be handled as distributions of molar fractions, referring to the number of distributed components, or distributions of mass fractions, referring to mass contributions of distributed components. In particular, for broad distributions, the difference between mass and molar distribution becomes significant and sometimes crucial. Molar mass distribution is a central piece in this puzzle of correlating molecular characteristics with polysaccharide performance. Additionally, optional branching characteristics, substitution patterns, and responses of aqueous polysaccharide systems to different kinds of applied stress need to be determined. 

---