DNA ion complexes were prepared from DNA and two forms of cationic surfactants, hexadecylpyridinium chloride (HDPyCl) (also known as cetylpyridinium chloride (CPC)) and hexadecyltrimethylammonium bromide (HDTMABr) (also known as cetyltrimethylammonium bromide (CTAB)), which are antibacterial and have the same sixteen carbons in their tail alkyl chains, but different polar head groups. The anionic DNA and the cationic surfactant were sufficiently reacted and washed well to obtain DNA ion complexes with equal moles. These films were prepared using iso-propanol. The bulk and surface structure of the films were examined and compared using small angle X-ray scattering (SAXS), a gas pycnometer, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), a static water contact angle meter, and atomic force microscopy (AFM). The two different DNA ion complex films consisting of surfactants with the same carbon number were found to be different in their DNA-DNA distances, film densities, and surface chemical compositions. Both films showed antibacterial properties.

In hot environments, evaporation is the most effective way to lose body heat. Excessive sweating rates cause dehydration, heat cramps and heat stroke. Therefore, reducing the thermal load on the human body by using water-containing clothing as a substitute for sweat is considered effective. We designed a cooling vest made of highly absorbent batting material covered with moisture-permeable and waterproof fabric and have continually improved the design. In this study, we modified the vest size to further enhance the cooling effect. Additionally, a hat was made using the same material as the vest. Wearing experiments were conducted in a hot environment controlled at 37 °C and 40% RH, simulating solar radiation. The participants included eight women in their twenties. The following experimental parameters were measured and evaluated: temperature and humidity within clothing (Tcl and Hcl), skin temperature (ts), sweating rate (Sw), tympanic temperature (Tty), and subjective evaluations. The effect of Type S (with a cooling item) was compared to that of Type A (without a cooling item). Consequently, it was found that reducing the size of the vest to fit the body has a higher cooling effect. When Type S was worn, the Tcl on the chest/back and ts on the chest reached values similar to those at the start of the experiment. Although the Sw for Type S was less than that of Type A, the increase in Tty was suppressed and body temperature remained almost constant. The subjective evaluation of Type S verified that it was neither hot nor stuffy. As regards Type S, we determined that the moisture transpiration from the cooling vest showed an excellent cooling effect synergistically with the fan-equipped blouson. However, the effect of the cooling cap could not be clarified.