(Almost) any adjective can be turned into a noun by putting the or a demonstrative pronoun (like those) before it, or another determiner (like all). In most cases, the result means "those people who are [adjective]".
those responsible = those who are responsible
the weak = people who are weak
all responsible = all who are responsible
In many cases, only some determiners are possible, depending on the adjective and the context; and some determiners may be more or less likely to be used than others, result in a different meaning depending on context, etc.
the possible (e.g. "what which is possible")
?all possible (I can't think of a context that would allow this)
those possible ("those things that are possible")
those hot enough ("those things that are hot enough"; less likely without a modifier)
When the adjective is unfit to describe people, either in context or intrinsically, adding the usually results in a meaning such as "the x-ness, the x aspect", or basically anything that would make sense elliptically. When talking about wires, "the red" refers to the red wire. It should be noted that adding the to such an adjective usually makes it singular, as opposed to "people adjectives" above.
Of course those does always result in a plural. When talking about tools, those available refers to those tools that are available. But, again, in many cases many determiners are impossible, especially the. In such cases, it usually becomes (all) the x one(s).
There is a connexion with adjectives that can come after their nouns in general, such as available (those tools available): such adjectives are more likely to allow determiners even if they are unfit for describing people. There is something that makes those adjectives more predicative, and predicative adjectives don't come before their nouns.