BackgroundAs a way of helping to sleep in winter, methods of warming the feet through footbaths or heating pads before bedtime are tried. In particular, bed socks are popular during winter sleeping in Korea, but scientific evidence about the physiological effects of bed socks on sleep quality is rarely reported. The purpose of this study was to evaluate the effect of feet warming using bed socks on sleep quality and thermoregulatory responses during sleep in a cool environment.MethodsSix young males (22.7 ± 2.0 years in age, 175.6 ± 3.5 cm in height, and 73.1 ± 8.5 kg in body weight) participated in two experimental conditions (with and without feet warming) in a random order. The following variables on sleep quality using a wrist actigraphy were measured during a 7-h sleep at an air temperature of 23 °C with 50% RH: sleep-onset latency, sleep efficiency, total sleep time, number of awakenings, wake after sleep onset, average awakening length, movement index, and fragmentation index. Heart rate and rectal and skin temperatures were monitored during the 7-h sleep. Questionnaire on sleep quality was obtained after awakening in the morning.ResultsThe results showed that sleep-onset latency was on average 7.5 min shorter, total sleep time was 32 min longer, the number of awakenings was 7.5 times smaller, and sleep efficiency was 7.6% higher for those wearing feet-warming bed socks during a 7-h sleep than control (no bed socks) (all P < 0.05). Also, their foot temperature was maintained on average 1.3 °C higher and the value in the distal-proximal skin temperature gradient was higher for those wearing feet warming bed socks when compared to the control condition (P < 0.05). However, there were no significant differences in heart rate, rectal and mean skin temperature, or in the questionnaire-based subjective evaluations between the two conditions.ConclusionsFeet warming using bed socks during sleep in a cool environment had positive effects on sleep quality by shortened sleep onset, lengthened sleep time, and lessened awakenings during sleep but had no significant influence on core body temperature. These results imply that sleep quality could be improved by manipulation of the foot temperature throughout sleeping.

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We report on a pathway to synthesize metal− organic frameworks (MOFs) using discarded textiles as a raw material. Discarded objects made of poly(ethylene terephthalate) (PET) could be an inexpensive and globally available source for 1,4-benzenedicarboxylic acid (H 2 BDC), also known as terephthalic acid, a building block of carboxylate-based MOFs. Previous studies on using discarded PET to synthesize MOFs have mainly focused on PET bottles. In contrast, we demonstrate the use of dyed polyester fabrics as a raw material. Specifically, we report on a synthesis path for copper-1,4-benzenedicarboxylate (CuBDC) utilizing disodium terephthalate (Na 2 BDC) as a linker and on how we obtained the linker from depolymerized polyester fabrics. To facilitate coordination between the copper ions and Na 2 BDC and create a localized acidic environment that favors the synthesis of CuBDC MOFs rather than metal oxide byproducts, we added acetic acid to the copper precursor solution. The drop-sized pHcontrolled domain enabled the formation of CuBDC MOF crystals at room temperature and at a fraction of time shorter than traditional solvothermal methods. We confirmed the resulting MOF structures using powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) spectroscopy, and our results were in quantitative agreement with previous reports. Furthermore, we used different copper salts as metal sources and different color-dyed polyester fabrics as linker sources, demonstrating the versatility of the proposed synthesis path. These results may open an avenue for using discarded textiles as a raw material and offer a more circular approach for managing textile waste.

Flexible and wearable pressure sensors have attracted significant attention owing to their roles in healthcare monitoring and human–machine interfaces. In this study, we introduce a wide-range, highly sensitive, stable, reversible, and biocompatible pressure sensor based on a porous Ecoflex with tilted air-gap-structured and carbonized cotton fabric (CCF) electrodes. The knitted structure of electrodes demonstrated the effectiveness of the proposed sensor in enhancing the pressure-sensing performance in comparison to a woven structure due to the inherent properties of naturally generated space. In addition, the presence of tilted air gaps in the porous elastomer provided high deformability, thereby significantly improving the sensor sensitivity compared to other dielectric structures that have no or vertical air gaps. The combination of knitted CCF electrodes and the porous dielectric with tilted air gaps achieved a sensitivity of 24.5 × 10−3 kPa−1 at 100 kPa, along with a wide detection range (1 MPa). It is also noteworthy that this novel method is low-cost, facile, scalable, and ecofriendly. Finally, the proposed sensor integrated into a smart glove detected human motions of grasping water cups, thus demonstrating its potential applications in wearable electronics.

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