Tough, Antifreezing, and Piezoelectric Organohydrogel as a Flexible Wearable Sensor for Human-Machine Interaction.

Piezoelectric hydrogel sensors are becoming increasingly popular for wearable sensing applications due to their high sensitivity, self-powered performance, and simple preparation process. However, conventional piezoelectric hydrogels lack antifreezing properties and are thus confronted with the liability of rupture in low temperatures owing to the use of water as the dispersion medium. Herein, a kind of piezoelectric organohydrogel that integrates piezoelectricity, low-temperature tolerance, mechanical robustness, and stable electrical performance is reported by using poly(vinylidene fluoride) (PVDF), acrylonitrile (AN), acrylamide (AAm), p-styrenesulfonate (NaSS), glycerol, and zinc chloride. In detail, the dipolar interaction of the PVDF chain with the PAN chain facilitates the crystal phase transition of PVDF from the α to ß phase, which endows the organohydrogels with a high piezoelectric constant d33 of 35 pC/N. In addition, the organohydrogels are highly ductile and can withstand significant tensile and compressive forces through the synergy of the dipolar interaction and amide hydrogen bonding. Besides, by incorporating glycerol and zinc chloride, the growth of ice crystals is inhibited, allowing the organohydrogels to maintain stable flexibility and sensitivity even at -20 °C. The real-time monitoring of the pulse signal for up to 2 min indicates that the gel sensor has stable sensitivity. It is believed that our organohydrogels will have good prospects in future wearable electronics.

All-Polymer Piezoelectric Elastomer with High Stretchability, Low Hysteresis, Self-Adhesion, and UV-Blocking as Flexible Sensor.

All-polymer piezoelectric elastomers that integrate self-powered, soft, and elastic performance are attractive in the fields of flexible wearable electronics and human-machine interfaces. However, a lack of adhesion and UV-blocking performances greatly hinders the potential applications of elastomers in these emerging fields. Here, a high-performance piezoelectric elastomer with piezoelectricity, mechanical robustness, self-adhesion, and UV-resistance was developed by using poly(vinylidene fluoride) (PVDF), acrylonitrile (AN), acrylamide (AAm), and oxidized tannic acid (OTA) (named PPO). In this design, the dipole-dipole interactions between the PVDF and PAN chains promoted the content of ß-PVDF, endowing high piezoelectric coefficient (d33, 58 pC/N). Besides, high stretchability (∼500%), supercompressibility (∼98%), low Young's modulus (∼0.02 MPa), and remarkable elasticity (∼13.8% hysteresis ratio) were achieved simultaneously for the elastomers. Inspired by the mussel adhesion chemistry, the OTA containing abundant catechol and quinone groups provided high adhesion (93.26 kPa to wood) and an exceptional UV-blocking property (∼99.9%). In addition, the elastomers can produce a reliable electric signal output (Vocmax = 237 mV) and show a fast response (24 ms) when subjected to external force. Furthermore, the elastomer can be easily assembled as a wearable sensor for human physiological (body pulse and speech identification) monitoring and communication.

Prediction and Analysis of Tourist Management Strategy Based on the SEIR Model during the COVID-19 Period.

Tourism destinations are now facing a dilemma choice of controlling the epidemic or developing the economy. This paper takes Macao, a typical international tourist city, as an example to study the strategy of tourist source control during the COVID-19 period. According to the published epidemic data of Macao, this study has established an improved SEIR (Susceptible-Exposed-Infected-Recovered) model, formulated six control strategies against the current epidemic, and used the model above to simulate the time required for all confirmed cases to recover and discharge under different strategies. By taking into consideration the gross revenue of Macao's gambling industry from 2017 to 2019, the impact of different strategies on the economy is predicted and three control strategies are found to be feasible. This study shows that an effective way to break through the above dilemma is to design the tourist management strategy by screening the source of passengers and controlling the upper limit of capacity of destination. These findings provide a scientific basis for tourism destinations in formulating public policies. The improved SEIR model is more consistent with the actual conversion rule of patients in the current COVID-19 epidemic, and it can be applied to further public health related research.

COVID-19: Short-Term Influence on China's Economy Considering Different Scenarios.

Recently, most countries have entered the outbreak period of the novel coronavirus epidemic. This sudden outbreak has caused a huge impact on the global economy, which has intensified the division of globalization and the recession of the global economy. Although the epidemic situation in China has gradually stabilized, the severe situation in the world still inevitably impacts China's economy. Based on the uncertainty of future epidemic, this paper sets up three scenarios to analyze the impact of the epidemic on China's economy. The first is that in June, the epidemic both at home and abroad is under control without rebound; the second is that the domestic epidemic is basically controlled but the foreign situation is not effectively controlled; the third is that the epidemic situation in China has a serious rebound due to the influence of the imported cases from abroad, which destroy the economy again. At the same time, some corresponding guidelines are put forward for the recovery of economy, and to minimize the economic losses as well as accelerate the pace of national economic recovery. In addition, it is believed that these suggestions may have certain reference value to other countries.

Crude Oil Price Fluctuation Analysis Under Considering Emergency and Network Search Data.

With the rapid development of the global economy, crude oil is becoming more and more prominent in terms of national stability. However, oil prices dramatically fluctuate during emergencies. Meanwhile, network search data have been widely used for prediction during the era of big data. Herein, a suggestion is introduced for improving the traditional case analysis. An autoregressive distributed lag model is established, considering emergency and network search data. Moreover, a network attention index of specific emergencies is used to explain fluctuations of the oil price and the influence of this attention is analyzed. Results show: 1) major emergencies have a significant short-term impact on the international oil market and a remarkable influence on the cumulative abnormal return of an event window, and 2) market attention can aggravate fluctuations of oil prices. It is found that the individual network attention paid to each of four emergencies has a significant impact on oil prices. The network attention related to Hurricane Katrina and the Libyan war has positive effects on oil prices. However, the effects of network attention paid to the subprime crisis and the Mexico oil spill of 2010 are negative. The attention paid to the subprime crisis has both the greatest and the longest lasting impact.

Gambling, Drinking and Quality of Life: Evidence from Macao and Australia.

The investigation of the interface between psychological constructs, compulsive consumption of alcohol and pathological gambling is an important avenue for development of future initiatives in social marketing or prevention programs. This cross-cultural study attempts to bridge the gap in literature by providing an evaluation of the predictive ability of psychological variables such as gambling urge, gambling-related erroneous cognitions and comorbid alcohol consumption on pathological gambling behaviour and its impact on overall quality of life indicators. Participants consist of 445 Macao and Australian young adults (Mean age = 23 years). Results indicate that probable pathological gamblers as compared with non-gamblers reported significantly lower quality of life in all domains-physical health, psychological well-being, social relationships and environment. Adults who drank more alcohol and have stronger erroneous cognitions evidenced higher pathological gambling behavior. Our research model fits both cohorts and interestingly, erroneous gambling-related cognitions serve as a full mediator for the predictive relationship between gambling urge and pathological gambling in the Macao sample, but serve as a partial mediator in the Australian sample. Targeting erroneous cognitions in future social marketing or preventive campaigns should demonstrate to be an important strategy in reducing the effects of urge to gamble among at-risk individuals. Further implications for the industry, marketing and governmental strategies are discussed.

Coupled effects of local movement and global interaction on contagion.

By incorporating segregated spatial domain and individual-based linkage into the SIS (susceptible-infected-susceptible) model, we propose a generalized epidemic model which can change from the territorial epidemic model to the networked epidemic model. The role of the individual-based linkage between different spatial domains is investigated. As we adjust the timescale parameter τ from 0 to unity, which represents the degree of activation of the individual-based linkage, three regions are found. Within the region of 0 < τ < 0.02 , the epidemic is determined by local movement and is sensitive to the timescale τ . Within the region of 0.02 < τ < 0.5 , the epidemic is insensitive to the timescale τ . Within the region of 0.5 < τ < 1 , the outbreak of the epidemic is determined by the structure of the individual-based linkage. As we keep an eye on the first region, the role of activating the individual-based linkage in the present model is similar to the role of the shortcuts in the two-dimensional small world network. Only activating a small number of the individual-based linkage can prompt the outbreak of the epidemic globally. The role of narrowing segregated spatial domain and reducing mobility in epidemic control is checked. These two measures are found to be conducive to curbing the spread of infectious disease only when the global interaction is suppressed. A log-log relation between the change in the number of infected individuals and the timescale τ is found. By calculating the epidemic threshold and the mean first encounter time, we heuristically analyze the microscopic characteristics of the propagation of the epidemic in the present model.