Alpha fractions

Starch is composed of macromolecular components, a-amylose and (i-aim -lose. The former reacts irreversibly with iodine to form a red adduct. (i-Aim losc. on the other hand, reacts with iodine forming a deep blue complex. Because this reaction is reversible, [3-amyl0sc is an excellent choice for the indicator. The undesired alpha fraction should be removed from the starch. The soluble starch that is commercially available, principally consists of (3-amylose. (3-Amylose is a polymer of thousands of glucose molecules. It has a helical structure into which iodine is incorporated as I5. ... 

More commonly, titrations involving iodine are performed with a suspension of starch as an indicator. The deep blue color that develops in the presence of iodine is believed to arise from the absorption of iodine into the helical chain of j8-amylose (see Figure 20-2), a macromolecular component of most starches. The closely related a-amylose forms a red adduct with iodine. This reaction is not easily reversible and is thus undesirable. In commercially available soluble starch, the alpha fraction has been removed to leave principally j8-amylose indicator solutions are easily prepared from this product. 

The alpha fractions for iron(II) and iron(III) can now be obtained from the activity ratios at selected E values in equation (12-7), since... 

In vasogenic oedema of white matter the fluid content, tissue sodium chloride and sodium potassium ratio are increased. Total proteins, albumins and alpha fractions 2ire also augmented [2, 3]. Incorporation of labelled amino acids into... 

Shell Higher Olefin Process) plant (16,17). C -C alcohols are also produced by this process. Ethylene is first oligomerized to linear, even carbon—number alpha olefins using a nickel complex catalyst. After separation of portions of the a-olefins for sale, others, particularly C g and higher, are catalyticaHy isomerized to internal olefins, which are then disproportionated over a catalyst to a broad mixture of linear internal olefins. The desired fraction is... 

Alpha-1-proteinase inhibitor and antithrombin III are used to treat people with hereditary deficiencies of these proteins. Both can be recovered from Cohn Fraction IV (Table 7) using ion-exchange chromatography (52) and affinity chromatography (197), respectively. Some manufacturers recover antithrombin III directiy from the plasma stream by affinity adsorption (56,198,199). 

The recovery area of the plant employs fractionation to recover and purify the phenol and acetone products. Also in this section the alpha-methylstyrene is recovered and may be hydrogenated back to cumene or recovered as AMS product. The hydrogenated AMS is recycled as feedstock to the reaction area. The overall yield for the cumene process is 96 mol %. Figure 1 is a simplified process diagram. 

This ester (70 g) and diethyl carbonate (250 mg) were stirred at 90°C to 100°C while a solution of sodium ethoxide [from sodium (7.8 g) and ethanol (1 54 ml)] was added over 1 hr. During addition, ethanol was allowed to distill and after addition distillation was continued until the column heat temperature reached 124°C. After cooling the solution to 90°C, dimethyl sulfate (33 ml) was followed by a further 85 ml of diethyl carbonate. This solution was stirred and refluxed for 1 hr and then, when Ice cool, was diluted with water and acetic acid (10 ml). The malonate was isolated in ether and fractionally distilled to yield a fraction boiling at 148°C to 153°C/0.075 mm, identified as the alpha-methyl malonate. This was hydrolyzed by refluxing for 1 hr at 2.5N sodium hydroxide (350 ml) and alcohol (175 ml), excess alcohol was distilled and the residual suspension of sodium salt was acidified with hydrochloric acid to give a precipitate of the alpha-methyl malonic acid. This was decarboxylated by heating at 180°C to 200°Cfor 30 minutes and recrystallized from petroleum ether (BP 80°C to 100°C) to give 2-(2-fluoro-4-biphenylyl)propionic acid, MP 110°C to 111°C. 

Silver was critical of the lack of use by plutonium chemists of a-coefficients. Assuming that Silver was referring to a-coeffi-cients defined as the fraction of the total concentration of a substance that exists as a particular species, he was wrong to say that plutonium chemists have not used them. Phil Horwitz at ANL has used them. Publications from ORNL have reported them to easily show relative concentrations of plutonium species, and L. M. Toth used such a-coefficients as percent of Pu(IV) polymer in his symposium talk Tuesday. Alpha coefficients are a commonly used, simple concept - certainly since Ringbom s article in the Journal of Chemical Education in 1958."... 

Caramel color interacts with other food components. As an example, a concentration higher than 700 ppm caramel in cola increased the rate of hydrolysis of the aspartame, forming alpha-L-aspartyl-L-phenylalanine. Caramelization products inhibited enzymic browning by 85.8 and 72.2% when heated at pH 4 and 6, respectively, for 90 min. The highest inhibitory activity was found for the fraction with molecular weight of 1000 to 3000. Caramel is often used for adulteration of juices and other foods like honey or coffee. It can be determined by quantification of marker molecules such as 5-HMF, 4-Mel, and DFAs. ... 

These high performance size exclusion separations of alpha-chymotrypsin SI and myosin light chains compare favorably with those achieved by ion exchange chromatography but require only a fraction of the time to accomplish. Furthermore, the very short retention times allow for separation of these labile proteins at room temperature, whereas operation at 0-40 C would otherwise be mandatory to avoid the loss of enzymatic activity. 

The use of nuclear techniques allows the determination of C, N, H, O, and heavier contaminants relative fractions with great accuracy, and of the elements depth profile with moderate resolution (typically 10 nm). Rutherford backscattering spectroscopy (RBS) of light ions (like alpha particles) is used for the determination of carbon and heavier elements. Hydrogen contents are measured by forward scattering of protons by incident alpha particles (ERDA) elastic recoil detection analysis [44,47]. 

Such alpha-recoil plays a fundamental role in fractionating the nuclides from one another in the low-temperature environment. During igneous processes, on the other hand, alpha recoil is probably not important in the generation of disequilibria ( °Th, Ra, and Pa). Beattie (1993) pointed out that the time scale of annealing of alpha decay damage at high temperatures was much shorter than the time scale of decay of these nuclides. 

While it is expected that the source rocks for the radionuclides of interest in many environments were deposited more than a million years ago and that the isotopes of uranium would be in a state of radioactive equilibrium, physical fractionation of " U from U during water-rock interaction results in disequilibrium conditions in the fluid phase. This is a result of (1) preferential leaching of " U from damaged sites of the crystal lattice upon alpha decay of U, (2) oxidation of insoluble tetravalent " U to soluble hexavalent " U during alpha decay, and (3) alpha recoil of " Th (and its daughter " U) into the solute phase. If initial ( " U/ U).4 in the waters can be reasonably estimated a priori, the following relationship can be used to establish the time T since deposition,... 

Early measurements of " Th were on seawater samples and Th was co-precipitated from 20-30 L of seawater with iron hydroxide (Bhat et al. 1969). This procedure may not recover all of the " Th in the sample, and an alpha emitting Th isotope (e g., °Th or Th) is added as a yield monitor. Following chemical purification of the Th fraction by ion exchange chromatography, the Th is electrodeposited onto platinum or stainless steel planchets. The planchets are then counted in a low background gas-flow beta detector to measure the beta activity and subsequently with a silicon surface barrier detector to determine the alpha activity of the yield monitor. The " Th activity is thus determined as ... 

Fig. 7.11 Inhibitory effect of alpha-Male urine on plasma Testosterone [T. ng/ml]. Exposure to urinary fractions in isolated (subordinate) male Mouse lemurs (N = 10) vs. castrate/adrenalectomised Ss, p < 0.001 vs. control (from Perret, 1995).

The effects of various enzymes on the activity of HPLC fractions that inhibited 3H-PCP binding were investigated. As shown in table 1, pronase (0.5 pg/ml), carboxypeptidase A (0.1 unit/ml), and trypsin (3.0 g/ml ) markedly decreased the potency of 10 n units of PCP-like activity. No significant change in activity was. seen when fractions were incubated with alpha-chymotrypsin. 

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