Enhanced capabilities of stain removal and comfort control are simultaneously achieved by the light and thermo dual-responsive copolymer poly(triethylene glycol methyl ether methacrylate-co-ethylene glycol methacrylate-coacrylamide azobenzene) (P(MEO 3 MA-co-EGMA-co-AAAB)) cross-linked on cotton fabrics. P(MEO 3 MA-co-EGMA-co-AAAB) is synthesized by sequential atom transfer radical polymerization with a molar ratio of 8 (MEO 3 MA):1 (EGMA):1 (AAAB). The MEO 3 MA units induce a thermoresponsive behavior to the copolymer. The hydrophilicity of the copolymer films can be further improved by the light-induced trans−cis isomerization of the AAAB units with UV radiation. The copolymer is facilely immobilized onto cotton fabrics with 1,2,3,4-butane tetracarboxylic acid as crosslinker. Due to the immobilization of P(MEO 3 MA-co-EGMA-co-AAAB), the hydrophilicity of the fabric surface is increased under UV radiation. Therefore, by simply installing a UV light source in the washing machine, better capability of stain removal is realized for the cross-linked cotton fabrics. It can prominently reduce the consumption of energy, water, and surfactants in laundry. In addition, the trans-AAAB units of the copolymer cause the cross-linked P(MEO 3 MA-co-EGMA-co-AAAB) layer to be more hydrophobic under ambient conditions. Hence, the copolymer can more easily collapse and form a porous structure on the fabrics. Thus, the air permeability of cotton fabrics cross-linked with P(MEO 3 MA-co-EGMA-co-AAAB) is enhanced by 13% at human body temperature as compared to P(MEO 3 MA-co-EGMA), giving improved comfort control during daily wear.

The classical Stefan problem for freezing (or melting) a sphere is usually treated by assuming that the sphere is initially at the fusion temperature, so that heat flows in one phase only. Even in this idealized case there is no (known) exact solution, and the only way to obtain meaningful results is through numerical or approximate means. In this study, the full two-phase problem is considered, and in particular, attention is given to the large Stefan number limit. By applying the method of matched asymptotic expansions, the temperature in both the phases is shown to depend algebraically on the inverse Stefan number on the first time scale, but at later times the two phases essentially decouple, with the inner core contributing only exponentially small terms to the location of the solidmelt interface. This analysis is complemented by applying a small-time perturbation scheme and by presenting numerical results calculated using an enthalpy method. The limits of zero Stefan number and slow diffusion in the inner core are also noted.

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In this work, the correlation between the whiteness of lighting and the preference for the colour of lighting was comprehensively investigated based on four psychophysical studies. Different sets of experimental light sources, two of constant correlated colour temperatures (CCT) and two of different CCTs were adopted to illuminate multiple experimental objects with different illuminance levels (200 lx or 500 lx). The observers were asked to rate their colour preference towards the illuminated objects and rate their white perception towards the illuminated environment of the empty light booth. It was found that for the studies with same CCT but different chromaticities, people indeed preferred whiter illumination. However, for the cases with multiple CCTs, that statement is only valid between 2500 K and 5500 K, since too white a light source impaired colour preference. In addition, based on the whiteness rating data, the performance of three typical metrics for white lighting was assessed. The findings of this study may contribute to a deeper understanding of colour and whiteness perception in lighting, especially for lighting designers and manufacturers.

In this study, two psychophysical experiments, one on colour preference and the other on colour discrimination, were conducted. To investigate the colour preference for blue jeans, 27 subjects with normal colour vision were asked to rate their visual appreciation of seven pairs of jeans with a colour gradient pattern. Nine LEDs, with uniformly sampled correlated colour temperature (CCT) values ranging from 2500 K to 6500 K, were used to illuminate the jeans. These lights produced a constant illuminance of approximately 200 lux, and their colour rendering indexes were between 79 and 91. In addition, using a Farnsworth-Munsell (FM)-100 Hue Test, the blue-region colour discrimination of 42 observers was assessed for five LEDs of the same type but with different CCTs (2500 K–6500 K, 1000 K interval). The results indicate that there is an optimum CCT of 5500 K for jeans, at which observers were found to exhibit the greatest capability for colour discrimination and the highest rating for colour preference. Interestingly, a significant gender difference was found in this study, which had not been observed in our previous work with quite similar experimental settings but different experimental objects. The findings of this study should provide a deeper understanding for the lighting design of shopping malls for jeans.