Effects of deformability, uneven surface charge distributions, and multipole moments on biocolloid electrophoretic migration

Liposomes have been widely used as cellular and bioparticle mimics due to their lipid bilayer structure and relative ease of production and manipulation. Such biocolloids are frequently characterized by capillary electrophoresis (CE), which promises a wealth of information about such properties as surface charge, composition, and rigidity. The applicability of this information is somewhat limited, however, since it is interpreted with colloidal theories that do not account for the unique properties of biocolloids. In this work, the effects of deformability, mobile surface charges, intrinsic polarizability, and uneven surface charge distributions are incorporated into colloidal theories in order to better model the electrophoretic behaviors of liposomes.     

Studies in qualitative inorganic analysis. V

Summary The interference of borate ion in the group separation of inorganic cations has been examined. Contrary to statements often made in text books, alkaline earth borates do not precipitate in Group III because they are soluble in the ammonium chloride present; Group IV metals [Zn, Co], which form more insoluble borates co-precipitate extensively in Group III when borate is present. It is essential, therefore, to remove most of the borate before precipitating Group III metals. A convenient-method for this removal is described.

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Zusammenfassung Die störende Wirkung von Boration bei der Gruppentrennung anorganischer Kationen wurde untersucht. Im Gegensatz zu Feststellungen vieler Lehrbücher fallen Erdalkaliborate nicht in der 3. Gruppe aus, da sie in Ammoniumchlorid löslich sind. Metalle der 4. Gruppe (Zn, Co), die schwerer lösliche Borate bilden, fallen bei Gegenwart von Borat weitgehend in der 3. Gruppe aus. Es ist daher wichtig, Borat vor der Fällung der 3. Gruppe größtenteils zu entfernen. Eine dazu geeignete Methode wird beschrieben.

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Résumé L'effet perturbateur de l'ion borate dans la séparation par groupes des cations minéraux a été étudié. Contrairement à ce qu'on peut lire souvent dans les livres d'analyse les borates alcalino-terreux ne précipitent pas dans le groupe III car ils sont solubles dans le chlorure d'ammonium qui est présent; les métaux du groupe IV (Zn, Co), qui donnent lieu à formation de borates plus insolubles, coprécipitent abondamment avec le groupe III en présence de borate. En conséquence, il est nécessaire d'éliminer la plus grande partie du borate avant de précipiter les métaux du groupe III. Les auteurs décrivent une méthode commode permettant de procéder à cette élimination.

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Part IV: Mikrochim. Acta [Wien] 1957, 137.     

The development of a sampler-sensor using a vanadium-oxinate-polymer film for the selective and direct determination of atmospheric ethanol

The development of a sensor for the direct and selective determination of atmospheric ethanol is in the initial stages. The sensor takes advantage of the selective chemical reaction between ethanol and vanadium oxinate. This reaction occurs in an organic medium where a red colored complex is the product. This reaction is determined spectrophotometrically where the absorbance maxima is 475 nm. The focus of this paper is to discuss the parameters necessary to develop a solid sorbent sampling-sensor which can be used to determine atmospheric ethanol.     

Orientational effects on atomic photoelectric cross sections and their relevance to photoelectron spectra from single crystals

We have examined the dependence of the photoelectric cross section from individual atomic orbitals and from groups of orbitals adapted to crystal symmetries in order to ascertain the relevance of this effect to the photoelectron spectra arising from single crystals.     

Reactions of sodium sulphide—I : With compounds containing hydroxyl groups

Aqueous solutions of sodium sulphide (ca 10%) reagent were reacted at 250° with compounds containing OH groups. This work was part of a programme designed to test the usefulness of the Na₂S solution degradation technique for determining the primary structure of humic acids. The compounds reacted here and the principal products detected (shown in brackets) were: cinnamyl alcohol (benzyl alcohol, benzoic acid, 3-phenylpropan-1-ol, 3-phenylpropionic acid), benzyl alcohol (little reaction), 3-phenylpropan-1-ol (little reaction), 1,2-dihydroxy-1-phenylethane (phenylacetic acid, acetophenone, 1-phenylethanol), catechol and hydroquinone (recovered starting compounds+ polymer products). Sodium hydroxide gave the same products with cinnamyl alcohol, but in different proportions. Possible mechanisms for these reactions are discussed.     

A biosensor for monitoring formaldehyde using a new lipophilic tetrathiafulvalene-tetracyanoquinodimethane salt and a polyurethane membrane

The fabrication and application of an end-column amperometric detection (AD) system with a carbon electrode for capillary-column liquid chromatography (CLC) were described. This new amperometric detector showed good sensitivity and stability in detecting the thiocompounds and other analytes with CLC. In order to obtain the better separation and detection performance for analytes, several operational parameters had been investigated: the working potentials, pH and flow rate. Under the optimum conditions, the method could effectively separate and determine cysteine (Cys), glutathione (GSH), dopamine (DA) and 6-thiopurine (6-TP). Good repeatability for retention time was obtained with a relative standard deviation (R.S.D.) value of 0.5%. The linear range covered over three orders of magnitude and the limits of detection were 8 fmol for cysteine, 20 fmol for glutathione, 8 fmol for dopamine and 20 fmol for 6-thiopurine. This method was successfully applied in determination of urinary sample with characteristics of simplicity, high sensitivity and good repeatability.     

Multi-step polymer-assisted solution-phase (PASP) library synthesis of functionalized diaminobenzamides

A parallel solution-phase library synthesis of functionalized diaminobenzamides is described. The four-step library synthesis is accomplished using polymer-assisted solution-phase (PASP) synthesis techniques. This high-yielding, multi-step sequence utilizes sequestering resins for the removal of reactants, reactant by-products, and employs a resin capture/release strategy as a key library synthesis step. Step one of the sequence relies on the displacement of an activated fluoro-group from the aromatic ring of 1a, b with a variety of primary amines to introduce the first diversity position. Step two is hydrolysis of the benzoate ester to a benzoic acid which is subsequently captured on a polyamine resin, washed, and released to give 4a, b in pure form. Step three utilizes PASP resins to mediate the amide coupling of a benzoic acid with a variety of primary amines to give the aminonitrobenzamides 5a, b and introduces the second diversity position. Step four is the parallel reduction of the aminonitrobenzamides 5a, b to the functionalized diaminobenzamides 6a, b. This library synthesis proceeds with high overall purities which average 80 % over the 4-step sequence.     

Examination of the electrophoretic behavior of liposomes

The electromigration of liposomes is a complex process resulting in many unexpected behaviors that are difficult to address with existing theories. In this study, the electrophoretic behaviors of liposome populations under various conditions were examined through the use of capillary electrophoresis and the results compared to classical electrokinetic, colloid, and spheroid theories. To elucidate the possible effects of applied field strength, bilayer rigidity, and surface charge on these behaviors, the electrophoretic mobilities of liposome populations were monitored while varying the applied potential, ionic strength of the medium, and the surface charge and cholesterol content of the liposomes. On the basis of comparisons made to the theoretical predictions, our results suggest that liposomal deformation and field-induced polarization may occur during electrophoresis and these mechanisms help to describe many of the observed behaviors.