J. Garcia Dominguez

Surface active molecules: preparation and properties of long chain nα‐acyl‐l‐α‐amino‐ω‐guanidine alkyl acid derivatives

A new route for the synthesis of long chain Nα‐acyl‐l‐α‐amino‐ω‐guamdine alkyl acid derivatives, with cationic or amphoteric character has been established. The general formula of these compounds is shown below.

The inhibitory effect of some amphoteric surfactants on the irritation potential of alkylsulphates.

The physico‐chemical and biological properties of an amphoteric/anionic system and its behaviour against a proteinic support have been thoroughly investigated. A considerable inhibition of adsorption of SLS (sodium lauryl sulphate) on human callus caused by the presence of definite amounts of AABet (alkyl‐amido‐betaines) in the treatment bath is observed. These physico‐chemical results are in agreement with those obtained by some in vivo biological tests. A mechanism of the process via the formation of mixed micelles is postulated emphasizing the stability of such systems as a function of pH, the influence of the chain length of the amphoteric surfactant and the molar relative ratio SLS/AABet. Consequently, our work offers the possibility of a wide applicability of the synergic mixtures of both types of surfactants to inhibit considerably skin irritation of cosmetic finished products.

EVALUATION OF TEXTILE DETERGENT EFFICIENCY OF MICROEMULSIONS IN SYSTEMS OF WATER NONIONIC SURFACTANT AND HYDROCARBON AT LOW TEMPERATURE

ABSTRACT Washing efficiency of microemulsions in water/nonionic surfactant/hydrocarbon systems has been evaluated. Such microemulsions have proved to have an excellent performance as cleaning systems in conditions of minimum mechanical energy and at low temperatures. Their behaviour in the presence of small amounts of an ionic surfactant as well as the modifications promoted by the presence of builders have also been investigated.

Spontaneous O2 release from SmBa2Cu3O7−x high Tc superconductor in contact with water

Abstract The high T c superconductors of compostion RBa 2 Cu 3 O 7−x (R = Y, La, lanthanide) are known to strongly react with water, which leads to compound decomposition and loss of their superconducting properties. A peculiar feature of this reaction is oxygen evolution. From a mass spectrometric analysis of the evolved oxygen we have been able to show that O 2 is released from the superconductor lattice. This unusual behaviour, which is specific of some metal peroxides, must be related to the peculiar electronic structure of these materials, and more concretely to the existence of O − and/or O 2 2− ions stabilized in the superconductor lattice. Our finding is consistent with the occurrence of holes delocalized in energy levels of O: 2p parentage, as recently found from angle resolved photoemission experiments with YBa 2 Cu 3 O 7 samples.

Programmed-temperature gas chromatography: Comparative study of retention temperatures on four unequally polar stationary phases

Abstract Retention temperatures ( T R ) of a series of solutes on four packec columns coated with OV-105, PS-255, di- n -decyl phthalate and OV-275 were measured at different programming rates and compared with other T R values calculated by some current equations, confirming that the equations of Curvers et al. , Krupcik et al. and Akporhonor et al. predict the retention temperatures closest to the observed T R values. Programmed-temperature retention indices (PTRIs) calculated by cubic splines interpolation of both the experimental and some other calculated T R values were also compared, taking the former as standard, the resulting PTRI values differing by only 2% for at least 90% of the solutes on the low-polarity stationary phases.

LIPOENKEPHALINS: A STUDY OF THE SURFACE ACTIVE AND PHARMACOLOGICAL PROPERTIES OF THESE NEW MORPHINE-LIKE PEPTIDES∗

ABSTRACT By modifying the physicochemical character of naturally occurring enkephalines, a parallelism between physicochemical behavior and pharmacological activity has been found. This was achieved by introducing alkyl residues of different chain length in position 1 or 5 on the enkephalin sequence. These kinds of substances can be referred to as 1ipoenkephalins and from a physicochemical point of view can be considered as surface active agents. On the other hand, as biological activity is greatly dependent on the conformation or orientation adopted by the molecule, we have also tried to investigate possible conformational or orientation changes when increasing the hydrophobic residue by means of optical rotation measurements and compression isotherm determinations. Finally, as the enkephalin molecule itself suffers an extremely rapid inactivation in brain tissues due to the proteolitic enzyme action, several tests to check the resistance of lipoenkephalins to en zymatic hydrolysis have been carried out,...

THE INTERACTION OF IONIC SURFACTANTS-RESINS FOR IMPROVING EXHAUSTION ADHESION AND SPREADING OF PREPOLYMERS ON KERATIN FIBRES

ABSTRACT A study of the effect of the aggregates formed between Hercosett and alkylsulphates (C8-C14) in preventing the shrinkage of wool samples pretreated with hydrogen peroxide is reported and a kinetic study of the formation of these aggregates as well as a mechanism by which they exhaust on wool fibres are suggested.

The Importance of Surface Active Molecules for Some Biological Phenomena

ABSTRACT Some biological phenomena which involve biological surfactants are treated It is shown how their properties of surface tension reduction and formation of association structures is widely applied in different biological systems It is very well known, that biochemical mechanisms occur in compartments with highly selective and individualized structure that function at any level. All these structural units are separated from the rest by interfaces. For instance, our skin can be considered as the interface that separates us from the surrounding air; each organ is differentiated from the rest of the living organism by a system of membranes with the ultimate cellular membrane.

31—INTERACTIONS BETWEEN ALKYLSULPHATES AND CATIONIC SHRINK-RESIST RESINS FOR WOOL PART II: THE INFLUENCE OF VARIOUS ALKYLSULPHATES ON THE SHRINKAGE OF KNITTED WOOL FABRICS

A study of the effect of the aggregates formed between Hercosett and alkylsulphates (C8–C14) in preventing the shrinkage of wool samples pre-treated with methylamine and hydrogen peroxide is reported. The amount of surfactant adsorbed on each pre-treated wool sample was estimated, and a mechanism by which the aggregate exhausts on the fibre is suggested.

23—STUDIES OF THE SULPHTTOLYSIS OF WOOL FIBRES PREVIOUSLY TREATED WITH IONIC SURFACTANTS

A study is reported in which wool fibres were pre-treated with ionic surfactants and subsequently subjected to sulphitolysis at different pH values in order to follow the chemical behaviour of cystine disulphide bonds in relation to that of bisulphite ions when surfactant molecules had previously been fixed on the protein. The influence of several parameters, such as the pH, concentration, temperature, and time of treatment of wool fibres with ionic surfactants, on the cystine reactivity was studied. Investigations of how treatment with alkylsulphates in the chain-length range C6–C16 modifies the reactivity of the native protein to sodium bisulphite are also reported.