{'fraction_non_alphanumeric': 0.037422037422037424, 'fraction_numerical': 0.016632016632016633, 'mean_word_length': 4.9079754601226995, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Phase Transition of N-Acyl Amino Acids with Different Acyl Group

The solid-liquid phase transitions of N-acyl amino acids with different acyl groups were investigated using a differential scanning calorimeter and an infrared spectrophotometer. The enthalpy and entropy changes of the transition increased by 3–5 kJ mol−1 and 8–10 J K−1mol−1, respectively, for an additional methylene group in N-acylglycine, and 7 kJ mol−1 and 18 J K−1mol−1, respectively, in the N-acyl-L,-alanine series. The same thermodynamic quantities of N-acylvalines were only slightly dependend on the acyl chain length, while they varied irregularly for the N-acylleucine series. Both the enthalpy and entropy were smaller for the L-form than for its racemic isomer in the N-acylleucines (C12 and above) and N-acylvalines. The differences of the thermodynamic quantities between the L- and DL-forms seems to result mainly from the difference of the molecular packing in the solid state.