h t t p://mihd.net/u8ihob is a link to RAR archive with several Excel tools to calculate thermodynamic parameters (dG, dH, dS, Tm) for DNA-DNA and RNA-DNA duplexes. The archive dna.rar (3.1 Mb) contains the following files: Thermodynamics_of_DNA-DNA_duplexes.xls, Thermodynamics_of_RNA-DNA_duplexes.xls, Melting_Temperature.xls, DNA_complexity_analysis_5mer.xls, DNA_complexity_analysis_7mer.xls, DNA_complexity_analysis_9mer.xls, DNA_complexity_analysis_11mer.xls. The first two files can be used to predict dG, dH, dS, and Tm of DNA-DNA or RNA-DNA duplexes according to nearest neighbor model. The third chart may be useful for quick assessment of Tm for DNA-DNA, DNA-RNA, and RNA-RNA duplexes in the presence of formamide. The last four files can be used to scan plasmid DNA sequence (size limit is 8001 bp) to estimate frequencies of 5-mer, 7-mer, 9-mer, or 11-mer repeats. I have found them useful to chose unique primers to amplify low-complexity targets. All charts are self-explanatory.