Filtration experiments were performed using a polyethersulfone (PES) ultra-filtration (UF) membrane with 30,000 molecular weight cut-offs (MWCO) to determine the effect of organic matter on flux in terms of hydrophilicity/hydrophobicity and distribution of molecular weight (MW).

And it is a mirror of the social status and intimacy.

Since they came into being,polite expressions have been changing as the society changes, resulting in 4 types of formal expressionos, namely, power, intimacy, interest, and relationship, which embody the features of modern polite expressions.