public Element getElement(String s) {
		if (s == null)
			return null;
		if (s.equalsIgnoreCase("nt"))
			return nt;
		if (s.equalsIgnoreCase("pl"))
			return pl;
		if (s.equalsIgnoreCase("ws"))
			return ws;
		if (s.equalsIgnoreCase("ck"))
			return ck;
		if (s.equalsIgnoreCase("mo"))
			return mo;
		if (s.equalsIgnoreCase("sp"))
			return sp;
		if (s.equalsIgnoreCase("ala"))
			return aminoAcidElement[ID_ALA - ID_ALA];
		if (s.equalsIgnoreCase("arg"))
			return aminoAcidElement[ID_ARG - ID_ALA];
		if (s.equalsIgnoreCase("asn"))
			return aminoAcidElement[ID_ASN - ID_ALA];
		if (s.equalsIgnoreCase("asp"))
			return aminoAcidElement[ID_ASP - ID_ALA];
		if (s.equalsIgnoreCase("cys"))
			return aminoAcidElement[ID_CYS - ID_ALA];
		if (s.equalsIgnoreCase("gln"))
			return aminoAcidElement[ID_GLN - ID_ALA];
		if (s.equalsIgnoreCase("glu"))
			return aminoAcidElement[ID_GLU - ID_ALA];
		if (s.equalsIgnoreCase("gly"))
			return aminoAcidElement[ID_GLY - ID_ALA];
		if (s.equalsIgnoreCase("his"))
			return aminoAcidElement[ID_HIS - ID_ALA];
		if (s.equalsIgnoreCase("ile"))
			return aminoAcidElement[ID_ILE - ID_ALA];
		if (s.equalsIgnoreCase("leu"))
			return aminoAcidElement[ID_LEU - ID_ALA];
		if (s.equalsIgnoreCase("lys"))
			return aminoAcidElement[ID_LYS - ID_ALA];
		if (s.equalsIgnoreCase("met"))
			return aminoAcidElement[ID_MET - ID_ALA];
		if (s.equalsIgnoreCase("phe"))
			return aminoAcidElement[ID_PHE - ID_ALA];
		if (s.equalsIgnoreCase("pro"))
			return aminoAcidElement[ID_PRO - ID_ALA];
		if (s.equalsIgnoreCase("ser"))
			return aminoAcidElement[ID_SER - ID_ALA];
		if (s.equalsIgnoreCase("thr"))
			return aminoAcidElement[ID_THR - ID_ALA];
		if (s.equalsIgnoreCase("trp"))
			return aminoAcidElement[ID_TRP - ID_ALA];
		if (s.equalsIgnoreCase("tyr"))
			return aminoAcidElement[ID_TYR - ID_ALA];
		if (s.equalsIgnoreCase("val"))
			return aminoAcidElement[ID_VAL - ID_ALA];
		if (s.equalsIgnoreCase("a"))
			return nucleotideElement[ID_A - ID_A];
		if (s.equalsIgnoreCase("c"))
			return nucleotideElement[ID_C - ID_A];
		if (s.equalsIgnoreCase("g"))
			return nucleotideElement[ID_G - ID_A];
		if (s.equalsIgnoreCase("t"))
			return nucleotideElement[ID_T - ID_A];
		if (s.equalsIgnoreCase("u"))
			return nucleotideElement[ID_U - ID_A];
		return null;
	}