James Swarbrick

Interaction of monomolecular films of biological significance with heavy metal ions and complexes at the air-water interface: I. Stearic acid and zinc, cadmium, and mercury

Abstract The interfacial interactions between stearic acid monolayers and the heavy metal ions, zinc, cadmium, and mercury have been investigated as part of a broader study investigating the effects of heavy metals on model monolayers simulating the human alveolus. The work has shown a strong interaction between the stearic acid film and ions in solutions of Zn, Cd, and Hg chloride. Changes in surface properties were caused by an interaction of the divalent cation of the salts with the negatively charged carboxyl head group of stearic acid. The affinity of the metal ions for the film molecules is in the order Cd > Zn > Hg. It is postulated that the interaction occurs in a 2:1 ratio of fatty acid to metal ion. While the cadmium as Cd2+ ion is present at a lower percentage at the same salt concentration compared to Zn, it had a greater effect on surface potential and a nearly equivalent effect on the surface pressure of the stearic acid films. The activity of the Hg2+ ion for causing changes in the surface properties of the films was much less than that observed for Zn and Cd. This may be related to the very low concentrations of Hg2+ present in the solutions studied, and may not be a true indication of the intrinsic Hg2+ ion affinity of the charged film site. Despite this low concentration, Hg2+ still had an observable effect on the stearic acid compression isotherm. The interactions studied may have implications related to the toxic and physiologic effects of heavy metals on living tissues.

Time-dependent surface behavior of dipalmitoyllecithin and lung alveolar surfactant monolayers

Abstract The time-dependent behavior of dipalmitoyllecithin and lung alveolar surfactant monolayers have been examined with an automated, recording film balance of conventional design. Surface pressure relaxation and recycling effects were observed. The results are interpreted in terms of molecular expulsion and solution processes peculiar to each of the films examined. These observations and explanations provide a clearer understanding of the phenomenon of surface hysteresis in monolayers. The surface films of lung alveolar surfactant consistently demonstrate a greater stability than those of dipalmitoyllecithin, even though the latter is a major component of lung alveolar surfactant. The surface phenomena reported support the proposal that lung alveolar surfactant exerts a stabilizing effect in the alveoli.

Some interfacial properties of alkylbenzyldimethylammonium chlorides

Abstract Surface tension lowering, equilibrium spreading pressure, and insoluble monolayer data are presented for a homologous series (C 8 and C 10 C 19 ) of alkylbenzyldimethylammonium chlorides (benzalkonium chlorides) in the presence and absence of excess electrolyte. In the presence of excess electrolyte, the surface tension lowering data adhered to Traubes rule; however, in the absence of electrolyte, significant deviation occurred. Surface pressure-molecular area isotherms were constructed from these surface tension lowering data in the ideal region and were compared in order to study the the effect of the electrolyte on the surface film. An “odd-even” chain length effect was seen in the equilibrium spreading pressures of the longer chain homologs. This is explained in terms of the melting point data. Studies of the monolayers formed at the air-water interface by the longer chain homologs were carried out and a molecular orientation in these monolayers is suggested.

Moisture permeation through polymer films

According to equation 2, the product of Rlcz t and t will be constant if the film system is behaving in accordance with F icks and Henry’s laws. Graphically, a plot of RlOut vs t will result in a hyperbola; when plotted on a log-log basis, a straight line with a slope of ~ 1 will result. This ideal system is shown in Fig. IA, lB, line 11. Moisture permeation data giving plots of log RWvt I’S log t with a slope of less than 1 (line I, Fig. IA, 1B) indicates that the effect of increasing film thickness is not as predicted by Fick‘s and Henry’s laws. In this case, moisture is permeating the film at a rate faster than would be expected. Conversely, data resulting in log-log slopes of greater than 1 (line 111, Fig. 1 A, 1B) are indicative of systems transmitting moisture a t a rate below that predicted by equation 2 as the film thickness is increased. If permeation is proceeding in accordance with equation 2, then P will be independent of t . Figure 1C shows the relation obtained when the data used in Fig. 1A and 1B is plotted in this manner. With the accelerated transmission of system I, P exhibits a positive deviation with increasing thickness. A negative deviation is shown by system 111. Only in the case of system 11, which is ideal, is P truly independent oft . It is reasonable to suppose that, in these theoretical examples, the polymer films exemplified by system I have an affinity for moisture which is not taken account of by Fick’s or Henry’s laws. Likewise system 111, where the data imply an active repulsion between water molecules and the film. In both cases, the closer the log-log slopes are to 1, the more ideal is the film. In a previous investigation on the water vapour transmission properties of three polymer film systems (Banker & others, 1966), linear log-log relations typical of system I were observed. With hydroxypropyl cellulose films and mixed Methocel : Ethocel films, both relatively hydrophilic systems, the slopes ranged from -0.389 to -0-468. With the more lipophilic butyl methacrylate films the slopes ranged from -0.672 to -0.701. The present authors have found a similar log-log relation with cast films of cellulose acetate hydrogen phthalate (CAP, Eastman Organic Chemicals, No. 4642) plasticized with diethyl phthalate. The results are presented in Table 1. In all cases the slope values are less than 1 and are of the same magnitude as the other cellulosic films studied previously. Taken as a whole, these results indicate that the greater the affinity of moisture for the polymer film system, the greater will the water transmission data deviate

Surface behavior of dibenzanthracene with lipid monolayers

Abstract The surface behavior of insoluble monolayers of lecithin-cholesterol mixed films and lecithin with two structural isomers of dibenzanthracene is reported. Surface pressure and surface potential findings are discussed in view of a previous report and published results of other workers. Results showed that cholesterol may be a membrane lipid capable of a critical interaction with carcinogen leading to tumor initiation.

Biological implications of cadmium-phospholipid monolayers

The potential interaction of air-borne metal pollutants with pulmonary lung surfactant may be simulated using monolayers of dipalmitoyl phosphatidyl choline (lecithin) spread on aqueous subphases containing different metal ions. Preliminary surface pressure and surface potential results indicate that cadmium interacts with dipalmitoyl phosphatidyl choline, such that the surface characteristics of the phospholipid are altered.

Organization Within the Pharmaceutical Industry - a Survey

AbstractA survey has been made of 12 U.S. and 5 U.K. companies in order to establish if there are any favored organizational structures in terms of pilot plant and related operations, production trouble shooting, clinical supplies manufacture and general engineering support services. Broad patterns of behavior become apparent in terms of the manner in which companies organize themselves to perform these functions. Communication, background and training of personnel and well-drawn lines of responsibility emerge as important factors in the efficient operation of the organizations surveyed.This survey was undertaken in order to establish if there are any favored organizational structures in terms of pilot plant and related operations, production trouble shooting, clinical supplies manufacture, and general engineering support services. Senior Research and Development and Manufacturing personnel in 12 U.S. and 5 U.K. companies were contacted individually and asked to participate. The confidentiality of the sur...