Extraction of vanadium into isobutyl methyl ketone

Because of its advantages in atomic-absorption spectroscopy, isobutyl methyl ketone was chosen as organic solvent for an extraction study on vanadium. Of eight chelating agents which were evaluated for completeness of extraction, ease of use, working pH range, and freedom from interference, cupferron was judged best.     

Bichromatic and Equichromatic Lines in ℂ2 and ℝ2

Let G and R each be a finite set of green and red points, respectively, such that |G|=n, |R|=n−k, G∩R=∅, and the points of G∪R are not all collinear. Let t be the total number of lines determined by G∪R. The number of equichromatic lines (a subset of bichromatic) is at least (t+2n+3−k(k+1))/4. A slightly weaker lower bound exists for bichromatic lines determined by points in ℂ². For sufficiently large point sets, a proof of a conjecture by Kleitman and Pinchasi is provided. A lower bound of (2t+14n−k(3k+7))/14 is demonstrated for bichromatic lines passing through at most six points. Lower bounds are also established for equichromatic lines passing through at most four, five, or six points.     

Lines, Circles, Planes and Spheres

Let S be a set of n points in ℝ³, no three collinear and not all coplanar. If at most n−k are coplanar and n is sufficiently large, the total number of planes determined is at least 1+k\binomn-k2-\binomk2(\fracn-k2)1+k\binom{n-k}{2}-\binom{k}{2}(\frac{n-k}{2}). For similar conditions and sufficiently large n, (inspired by the work of P.D.T.A. Elliott in Acta Math. Sci. Hung. 18:181–188, 1967) we also show that the number of spheres determined by n points is at least 1+\binomn-13-t₃^orchard(n-1)1+\binom{n-1}{3}-t_{3}^{\mathrm{orchard}}(n-1), and this bound is best possible under its hypothesis. (By t₃^orchard(n)t_{3}^{\mathrm{orchard}}(n), we are denoting the maximum number of three-point lines attainable by a configuration of n points, no four collinear, in the plane, i.e., the classic Orchard Problem.) New lower bounds are also given for both lines and circles.     

Repeated Angles inE 4

Let there be givenn points in four-dimensional euclidean spaceE ₄. We show that the number of occurrences of the angle iso(n ³) if is not a right angle and (n ³) otherwise.     

The high-performance liquid chromatography and detection of phospholipids and triglycerides: Part 1. Nonpolar stationary phase chromatographic behavior in ultraviolet transparent mobile phases

The liquid chromatographic retention behavior of triglyceride and phospholipid molecular species in the nonpolar stationary (reverse) phase mode is presented for mobile phases compatible with ultraviolet detection. Interpretation of the results by means of the Kovats retention index suggests that correlation of retention to structure requires information on the number of acyl double bonds contained within the lipid molecular species in question. This, in turn, indicates that detection plays a major role in elucidating lipid structure because insufficient information is contained in the chromatographic retention data.     

Coulometric titration of proteins with silver

The sulfhydryl groups of some proteins were studied by a coulometric argentometric titration; disulfide groups in the presence of sulfite were titrated by the same technique. Direct procedures and a technique utilizing excess coulometrically generated silver(I) were used. The latter method enabled small samples (20–1000 μg of protein) to be titrated with a precision of less than 4%. The proteins were generally titrated in both the native state and the denatured state (8 M urea). Bovine serum albumin, α-chymotrypsin, glutathione reductase, human hemoglobin, insulin, β-lactoglobulin, and ovalbumin were examined and the results compared to those of previous workers.     

Characterization of plasma apolipoproteins by capillary electrophoresis.

The main apolipoproteins of plasma high-density lipoproteins (HDL) and low-density lipoproteins (LDL) were analyzed by capillary electrophoresis. Where possible the results were compared with slab sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis. Addition of the detergent SDS to the running buffer was essential for separation. Separations were carried out in bare silica and polyacrylamide-coated capillaries. The main apolipoproteins of HDL could be separated in an uncoated capillary filled with borax buffer containing 0.1% SDS. Using the coated capillary, a mixture of HDL and LDL apolipoproteins was resolved in less than 12 min. These preliminary studies indicate that capillary electrophoresis is a promising technique for screening plasma apolipoproteins.     

Analysis of the phospholipid composition of plasmodium knowlesi and rhesus erythrocyte membranes

Methods for the separation and analysis of the phospholipid classes have been studied. The lipid extracts of normal and Plasmodium knowlesi- infected rhesus erythrocytes and of the parasite itself have been examined for phospholipid composition on an animal-to-animal basis. Several differences were apparent between the phospholipids of parasites and infected host cells. Phosphatidylinositol, phosphatidylcholine, and phosphatidylethanolamine represented larger percentages in the parasite than in the host; the average phosphatidylinositol content was 1.8 % in infected host cells and 4.3 % in parasites. Sphingomyelin and phosphatidylserine were also strikingly different in the two membranes; in the parasite they averaged less than 20 % and 33 % respectively of their level in the infected red blood cell.