Abstract The notion of Λ-fuzzy set was introduced by M. E. EI-Shafei and A. Zakari in 2006 ((20)). We examine some basic properties of it and prove some characterization theorems for the same. The paper presents a new class of fuzzy sets called fuzzy Λγ-sets that includes the class of all fuzzy γ-open sets. It also introduces the notion of fuzzy Vγ-sets as the dual concept of fuzzy Λγ sets to study the spaces constituted by those sets and obtain a completely different structure which is called fuzzy independent Alexandorff space. A stronger form of fuzzy Λb - continuity ((2)) called fuzzy Λγ-continuity is introduced and the relationships are also established with the already existing functions accordingly. Finally, fuzzy Λγ-Generalized closed sets are defined and studied with some of their applications.

Polysulfone membranes are prepared through phase separation technique, introduced by Loeb-Sourirajan. The viscous polymer solution (in dimethyl formamide) is first spread into the thin film, and then immersed in gelation medium (water). The influence of polymeric additive, (poly(ethylene glycol) (PEG)) in the formation of the pores during phase separation in gelation bath (i.e. from the polymer poor phase, which appears at the phase separation) is explored. The effects of different molecular weight (Mw) of PEG in the gelation bath regarding the differential filter flows of nitrogen as well as their concentration are reflected from the porometry studies. The pore distribution is shifted as the molecular weight of PEG used in the gelation bath. The bubble point and mean flow pore diameters vary with the concentration as well as their molecular weight of PEG.

Se prepararon membranas de polisulfona mediante la técnica de separación de fase, introducida por Loeb-Sourirajan. La solución del polímero viscoso (en dimetilformamida) se esparce dentro de la película delgada, y se sigue por una inmersión en el medio de gelación (agua). Se explora la influencia del aditivo polimérico (poli(etilénglicol) (PEG)) en la formación de los poros durante la fase de separación en el baño de gelación (desde la fase escasa en polímero, la cual aparece en la separación de fases). De los estudios de porometría, se observan los efectos en las diferencias en peso molecular del PEG en el baño de gelación sobre los flujos diferenciales de nitrógeno así como de la concentración. La distribución de poros se desplaza de acuerdo con el peso molecular del PEG empleado en el baño de gelación. El punto de burbujeo y la media en los diámetros de los poros de flujo varían en función de la concentración y del peso molecular del PEG.