Objective We examined the psychological impact of the 2003 outbreak of severe acute respiratory syndrome (SARS) on hospital employees in Beijing, China. Methods In 2006, randomly selected employees (n = 549) of a hospital in Beijing were surveyed concerning their exposure to the 2003 SARS outbreak, and the ways in which the outbreak had affected their mental health. Results About 10% of the respondents had experienced high levels of posttraumatic stress (PTS) symptoms since the SARS outbreak. Respondents who had been quarantined, or worked in high-risk locations such as SARS wards, or had friends or close relatives who contracted SARS, were 2 to 3 times more likely to have high PTS symptom levels, than those without these exposures. Respondents’ perceptions of SARS-related risks were significantly positively associated with PTS symptom levels and partially mediated the effects of exposure. Altruistic acceptance of work-related risks was negatively related to PTS levels. Conclusions The psychological impact of stressful events related to an infectious disease outbreak may be mediated by peoples’ perceptions of those events; altruism may help to protect some health care workers against these negative impacts.

Two-dimensional (2D) transition metal carbides and nitrides (MXenes) have shown outstanding performances in electrochemical energy storage and many other applications. Delamination of MXene flakes in water produces colloidal solutions that are used to manufacture all kinds of products (thin films, coatings, and electrodes, etc.). However, the stability of MXene colloidal solutions, which is of critical importance to their application, remains largely unexplored. Here we report on the degradation of delaminated-Ti3C2T x colloidal solutions (T represents the surface functionalities) and outline protocols to improve their stability. Ti3C2T x MXene solutions in open vials degraded by 42%, 85%, and 100% after 5, 10, and 15 days, respectively, leading to the formation of cloudy-white colloidal solutionss containing primarily anatase (TiO2). On the other hand, the solution could be well-preserved when Ti3C2T x MXene colloidal solutionss were stored in hermetic Ar-filled bottles at 5 °C, because dissolved oxygen, the main oxidant of the MXene flakes, was eliminated. Under such a recipe, the time constant of the solution was dramatically increased. We have found that the degradation starts at the edges and its kinetics follows the single-exponential decay quite well. Moreover, we performed size selection of the MXene solution via a cascade technique and showed that the degradation process is also size-dependent, with the small flakes being the least stable. Furthermore, a dependence between the degradation time constants and the flake size allows us to determine the size of the nanosheets in situ from UV–vis spectra and vice versa. Finally, the proposed method of storing the MXene colloidal solution in Ar-filled vials was applied to Ti2CT x to improve its stability and time constant, demonstrating the validity of this protocol in improving the lifetime of different MXene solutions.

Tough and self-healable hydrogels have been prepared by the multiple supramolecular interactions of clay nanosheets with dendritic polymers or in situ-formed polymer. [ 10 ] Many workers have studied ionic gels formed by the supramolecular effect of ionic liquids and block copolymers with/without SiO 2 nanofi ller, which also demonstrate the high mechanical modulus. [ 11 ] Here, we employ a mild self-initiated UV polymerization to prepare an ionic conducting polymer gel, whose non-covalent crosslinking interaction can endow the conducting gel compressive toughness and self-recovering ability.Our system consists of four components: 1-ethyl-3-methylimidazolium chloride (EMIMCl), hydroxyethyl methacrylate (HEMA), chitosan (CS) and water, whose molecular structures have been shown in Figure 1 A. At fi rst, CS and HEMA are dissolved in EMIMCl via heating and cooling process, which forms a viscous solution from the solid of EMIMCl (Figures S1a and 1C). The destroy of crystal structure of EMIMCl is the main reason to form such homogeneous solution, which is caused by the dissolution of CS and HEMA through hydrogen bond. [ 12 ] Then, tough EMIMCl gels can be formed by irradiating the asprepared homogeneous solution with UV light (Figures S1b and S2; Figure 1 D). The UV-generated Cl radicals from EMIMCl (Figure 1 B) are the initiator for the polymerization of HEMA. [ 13 ] The physical gelation of our EMIMCl gel without crosslinker should be ascribed to the hydrogen bonding interactions between the hydroxyl group in PHEMA, the amine group of CS and imidazolium group in solvent. Interesting is that our EMIMCl gel is miscible with water, which has a slightly decrease strength but a sharply increase ionic conductivity (Figure 1 E). As shown in Figure S3, water exists in the form of free water and bound water, and is relatively stable at room temperature ( Figure S4). The fi nal EMIMCl/water gel exhibits the water and pressure controlled ionic conductivity, which is suitable as an appropriate electrolyte and separator in fl exible supercapacitors. The detailed preparation, mechanism and properties are shown as followed.The EMIMCl gels can be formed by irradiating the as-prepared homogeneous solution under 45 minutes UV light with intensity of 22.4 mw/cm 2 at 365 nm. The component ratio of the conducting gel is optimized by the comprehensive evaluation of the electrochemical performances and mechanical strength. Finally, a varying amount of water was injected into the EMIMCl gel to form EMIMCl/water gels with 5 to 50 wt% (by mass) water content (Figure 1 E). If the water was added in advance, the fi nal gel could not be obtained. The EMIMCl/water gel shows high toughness when they underwent large deformations and show good strength under compression ( Figure 2 Flexible devices are a mainstream direction in modern electronics and related multidisciplinary fi elds. [ 1 ] Concerning fl exible capacitors and batteries, the current research is mainly focused on the fabrication of fl exible electrode materials; [ 2 ] however, ele...

Fluorinated graphene with tuneable F-loading amount and properties was prepared via a facile solution approach using graphene oxide and liquid diethylaminosulfur trifluoride (DAST) as starting materials under mild conditions.

The performance of lithium-ion battery packs are often extrapolated from single cell performance however uneven currents in parallel strings due to cell-to-cell variations, thermal gradients and/or cell interconnects can reduce the overall performance of a large scale lithium-ion battery pack. In this work, we investigate the performance implications caused by these factors by simulating six parallel connected batteries based on a thermally coupled single particle model with the solid electrolyte interphase growth degradation mechanism modelled. Experimentally validated simulations show that cells closest to the load points of a pack experience higher currents than cells further away due to uneven overpotentials caused by the interconnects. When a cell with a four times greater internal impedance was placed in the location with the higher currents this actually helped to equalise the cell-to-cell current distribution, however if this was placed at a location furthest from the load point this would cause a ~6% reduction in accessible energy at 1.5 C. The influence of thermal gradients can further affect this current heterogeneity leading to accelerated aging. Simulations show that in all cases, cells degrade at different rates in a pack due to the uneven currents, with this being amplified by thermal gradients. In the presented work a 5.2% increase in degradation rate, from-7.71 mWh/cycle (isothermal) to-8.11 mWh/cycle (non-isothermal) can be observed. Therefore, the insights from this paper highlight the highly coupled nature of battery pack performance and can inform designs for higher performance and longer lasting battery packs.

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