{'fraction_non_alphanumeric': 0.011294526498696786, 'fraction_numerical': 0.007819287576020852, 'mean_word_length': 5.329670329670329, '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}}
Comparison of cooling criteria with a cryogen spray and water/air spray

Skin cooling using a cryogen spray (tetrafluoroethane) has been shown to dramatically reduce the skin surface temperature whilst predictions show that the underlying dermal tissue is unaffected. This technique is repeated with a chilled water spray, along with a continuous airflow to enhance evaporation. Radiometric skin surface temperature measurements are recorded during trials utilizing this technique and the results are compared with theoretical predictions in order to determine the mechanism by which the heat is removed from the skin. The optimum spray conditions are achieved when the water is chilled to around 2 degrees Celsius with a continuous airflow of 50 liters/minute. Under these conditions skin surface temperature reduction is about 8 degrees Celsius - 10 degrees Celsius. The measured radiometric skin surface temperature change indicates that the mechanism by which this process removes heat from the skin is predominantly evaporation. Predictions of skin temperature change with varying skin depth indicate that the optimum spray time is around 100 ms.