Multi-layer ferroelectrets consisting of fluoroethylenepropylene (FEP) copolymer and open-porous expanded polytetrafluoroethylene (ePTFE) films exhibit stable internal electret charges, high piezoelectric coefficients and heat resistance, making them promising candidates for wearable sensors or nanogenerators in body-area networks. Here, three- and five-layer (FEP/ePTFE/FEP and FEP/ePTFE/FEP/ePTFE/FEP) ferroelectret stacks were laminated and poled in a corona discharge. The resulting charge distributions were measured by use of the pulsed electro-acoustic (PEA) method and revealed that charges of opposite polarity were trapped at the interfaces between the FEP and ePTFE layers. Thus, the existence of one macro-dipole in the three-layer structure and of two macro-dipoles in the five-layer structure was directly shown for the first time. Moreover, electric-displacement-versus-electric-field (D-E) loops revealed that remnant polarization is given by the number of macro-dipoles in the respective stack. Due to the addition of the macro-dipoles, the piezoelectric d ₃₃ coefficient of the FEP/ePTFE/FEP/ePTFE/FEP stack reaches 200 pC/N even under a potentially non-uniform compression of the soft ePTFE layers. The results should be useful for a better understanding and a performance optimization of ferroelectrets in self-powered intelligent devices.

In contrast to molecular-dipole polymers, such as PVDF, ferroelectrets are a new class of flexible spatially heterogeneous piezoelectric polymers with closed or open voids that act as deformable macro-dipoles after charging. With a spectrum of manufacturing processes being developed to engineer the heterogeneous structures, ferroelectrets are made with attractive piezoelectric properties well-suited for applications, such as pressure sensors, acoustic transducers, etc. However, the sources of the macro-dipole charges have usually been the same, microscopic dielectric barrier discharges within the voids, induced when the ferroelectrets are poled under a large electric field typically via a so-called corona poling, resulting in the separation and trapping of opposite charges into the interior walls of the voids. Such a process is inherently self-limiting, as the reverse internal field from the macro-dipoles eventually extinguishes the microdischarges, resulting in limited density of ions and not too high overall piezoelectric performance. Here, a new method to form ferroelectrets with gigantic electroactivity is proposed and demonstrated with the aid of an external ion booster. A laminate consisting of expanded polytetrafluoroethylene (ePTFE) and fluorinated-ethylene-propylene (FEP) was prefilled with bipolar ions produced externally by an ionizer and sequentially poled to force the separation of positive and negative ions into the open fibrous structure, rendering an impressive piezoelectric d33 coefficient of 1600 pC/N an improvement by a factor of 4 in comparison with the d33 of a similar sandwich poled with nonenhanced corona poling. The (pre)filling clearly increases the ion density in the open voids significantly. The charges stored in the open-cell structure stays at a high level for at least 4 months. In addition, an all-organic nanogenerator was made from an ePTFE-based ferroelectret, with conducting poly(3,4-ethylene dioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) coated fabric electrodes. When poled with this ion-boosting process, it yielded an output power twice that of a similar sample poled in a conventional corona-only process. The doubling in output power is mainly brought about by the significantly higher charge density achieved with the aid of external booster. Furthermore, aside from the bipolar ions, extra monopolar ions can during the corona poling be blown into the open pores by using for instance a negative ionic hair dryer to produce a unipolar ePTFE-based ferroelectret with its d33 coefficient enhanced by a factor of 3. Ion-boosting poling thus unleashes a new route to produce bipolar or unipolar open-cell ferroelectrets with highly enhanced piezoelectric response.

Developing a group of good safety professionals is a key foundation for improving a country's work safety and health. In China, the widespread concern and discussion on the development of safety professionals, or more specifically Certified Safety Engineers (CSEs) started in the early 1990s. In recent years, especially after 2002, China's CSEs entered into a holistic, systematic and rapid development period because of the formal establishment and implementation of the professional qualification system for CSEs in 2002. Moreover, CSE is now becoming the most important profession in the field of work health and safety in China, and it has been officially approved by the central government. China has rich experiences on the development and cultivation of CSEs. However, these experiences were little known to the outside world due to the lack of efficient communication. Firstly, this paper briefly reviews the history and development of CSEs in China. Then, the administrative regulation and important requirements (such as capacity requirements and the knowledge framework) regarding CSEs in China are briefly introduced. This research aims at promoting the cooperation and exchange of information on the development and cultivation of safety professionals between China and other countries, to offer useful evidence and suggestions for the development of safety professionals.

China has been experiencing dynamic industrialization because of rapid economic growth. Even with steady industrial safety improvements in recent years in China, the death rate per accident is increasing, and major accidents (MAs) as well as particularly serious accidents (PSAs) are still occurring every year. Evidently, the risk of industrial accidents, especially of MAs and PSAs is still high. Moreover, China has entered a bottleneck period for the prevention and control of MAs and PSAs. In a word, MAs and PSAs have become a significant challenge for China's industrial, social, and economic development. In recent years, especially since 2016, great attention of the Chinese government has been given to the prevention and control of MAs and PSAs. China launched its nationwide safety campaigns for firmly curbing MAs and PSAs. Some potentially effective measures and strategies in a series of safety policy documents (e.g., the ‘Guidelines for Comprehensively and Resolutely Curbing MAs and PSAs’ and the ‘Thirteenth-Five-Year Plan for Work Safety’) were also proposed, to reduce MAs and PSAs. Firstly, this paper makes a statistical analysis of China's MAs and PSAs between the year of 2002 and 2016 to figure out the current status of MAs and PSAs in China. Then this article reviews some latest major events of the prevention and control of MAs and PSAs in China to introduce the recent efforts in the prevention and control of MAs and PSAs in China. Finally, according to a series of safety policy documents in China, and the scientific research literature from other countries, this study gives a brief introduction to the future prospects of the prevention and control of MAs and PSAs in China. Obviously, this study can provide useful evidence and suggestions for the future prevention and control of MAs and PSAs both within China and in other countries.

China is a major country producing and using hazardous chemicals. Unfortunately, the hazardous chemical industry is still one of the most high-risk industries in China. In recent years, especially after two devastating hazardous chemical accidents, namely “Qingdao 11.2 Crude Oil Leaking and Explosion Accident” and “Tianjin Port 8.12 Fire and Explosion Accident” which occurred in 2013 and 2015 respectively, China has attached great importance to hazardous chemical safety. The period between 2016 and 2017 is a crucial period for the future direction of hazardous chemical safety in China because China released a series of important government documents (such as ‘Thirteenth Five-Year (2016–2020) Plan for Hazardous Chemical Safety’ and ‘Comprehensive Plan for Hazardous Chemical Safety Management (December 2016–November 2019)’) to promote hazardous chemical safety in the future. What is the future development of China's hazardous chemical safety? To answer this question, this paper attempts to briefly analyze and introduce the opportunities, problems, challenges and tasks of the future of safety with hazardous chemical industrial activities in China, according to the current situation of hazardous chemical safety in China and using the latest government documents and studies. Obviously, this study can provide useful evidence and suggestions for the future of safety management in the hazardous chemical industry both within China and in other countries.