Cost-Effective Fabrication of Micro-Nanostructured Superhydrophobic Polyethylene/Graphene Foam with Self-Floating, Optical Trapping, Acid-/Alkali Resistance for Efficient Photothermal Deicing and Interfacial Evaporation.

Solar evaporation is one of the most attractive and sustainable approaches to address worldwide freshwater scarcity. Unfortunately, it is still a crucial challenge that needs to be confronted when the solar evaporator faces harsh application environments. Herein, a promising polymer molding method that combines melt blending and compression molding, namely micro extrusion compression molding, is proposed for the cost-effective fabrication of lightweight polyethylene/graphene nanosheets (PE/GNs) foam with interconnected vapor escape channels and surface micro-nanostructures. A contact angle of 155 ± 2°, a rolling angle of 5 ± 1° and reflectance of ≈1.6% in the wavelength range of 300-2500 nm appears on the micro-nanostructured PE/GNs foam surface. More interestingly, the micro-nanostructured PE/GNs foam surface can maintain a robust superhydrophobic state under dynamic impacting, high temperature and acid-/alkali solutions. These results mean that the micro-nanostructured PE/GNs foam surface possesses self-cleaning, anti-icing and photothermal deicing properties at the same time. Importantly, the foam exhibits an evaporation rate of 1.83 kg m-2 h-1 under 1 Sun illumination and excellent salt rejecting performance when it is used as a self-floating solar evaporator. The proposed method provides an ideal and industrialized approach for the mass production of solar evaporators suitable for practical application environments.

Green Synthesis of Carbon Nitride-Based Conjugated Copolymer for Efficient Photocatalytic Degradation of Tetracycline.

Upcycling waste plastics into advanced semiconductor photocatalysts provides a new strategy to reasonably and economically solve the huge amount of waste plastics, which remains challenging. Herein, a carbon nitride-based donor-acceptor (D-A) conjugated copolymer by copolymerization of dicyandiamide and terephthalic acid from discarded polyethylene terephthalate (PET) using Zn(OH)2 as catalyst and template at 360-440 °C is synthesized. The morphology and structure of the conjugated copolymer are well regulated by the calcination temperature. The resultant conjugated copolymer exhibits merits of high light absorption and low electron-hole recombination probability. Consequently, it works excellently in the persulfate-based advanced oxidation process for visible light-driven photocatalytic degradation of tetracycline. The kinetic constant (3.4 × 10-2  min-1 ) is 40.5 and 2.3 times that of the conjugated copolymer system and persulfate system, respectively. Furthermore, the reactive species (including •OH, SO4 •- , •O2 - , 1 O2 , and h+ ) and degradation intermediates of tetracycline are analyzed to expound its degradation process. This work not only pioneers design guidelines on upcycling of waste plastics in a sustainable manner, but also provides a facile strategy to synthesize carbon nitride-based D-A conjugated copolymers for the efficient activation of persulfate-based advanced oxidation process in wastewater treatment.

High transparency, degradable and UV-protective poly(lactic acid) composites based on elongational rheology and chain extender assisted melt blending.

Conventional polylactic acid (PLA) melt plasticization and toughening processes are typically achieved at the expense of PLA strength and transparency, which is clearly detrimental to its application in areas such as smart home and food packaging. Herein, an ultraviolet (UV)-protective PLA-based composite (PP6) that simultaneously achieves high strength (63.3 MPa), high plasticity (125.3 %), and enhanced toughness (4.3 kJ/m2) by adding only 6 wt% poly(3-hydroxybutyrate-4-hydroxybutyrate) (P34HB) under the assist of 1 wt% chain extender was prepared using melt blending technique. Benefiting from the cross-linking effect of the chain extender and the elongational flow during processing, the compatibility between P34HB and PLA, as well as the thermomechanical properties, heat resistance, and biodegradable properties of the composite, have been enhanced significantly. The extremely low melt enthalpy (1.9 J/g) and the low crystallinity PLA phase contribute to an appropriate transparency (78.3 % of glass in 400-1100 nm). The prepared composites display mid- and long-wave UV-protective performance, which is superior to conventional industrial glasses. Through the superior elongational rheology technology, PP6 maintains favorable overall properties even after six thermomechanical cycles. Collectively, the composite fabricated in this work is an attractive candidate for future applications such as smart windows, food packaging, agricultural films, and biomedical applications.

Plant-Mimetic Vertical-Channel Hydrogels for Synergistic Water Purification and Interfacial Water Evaporation.

The integration of renewable solar energy-driven interfacial evaporation and photocatalysis has recently emerged as one of the most promising technologies for simultaneous freshwater production and pollutant removal. However, the construction of an advanced integrated system with the merit of a fast supply of water and pollutant molecules remains challenging for efficient solar-driven evaporation and photocatalytic performance. Herein, inspired by the transpiration of plants, we fabricate a biomimetic, vertically channeled polypyrrole/foam-like carbon nitride/poly(vinyl alcohol) hydrogel (PCH) by directional freeze-drying. We prove that the vertically aligned channels not only reduce heat loss and improve energy conversion efficiency but also facilitate the transport of water and organic pollutants to the air-water interface. Benefiting from the advantages above, the PCH evaporator presents a high solar evaporation efficiency of 92.5%, with the evaporation rate achieving 2.27 kg m-2 h-1 under 1 kW m-2 irradiation, exceeding many advanced interfacial solar-driven evaporators. Meanwhile, PCH reaches a degradation efficiency of 90.6% within 1 h when dealing with tetracycline (a typical antibiotic)-polluted water, remarkably higher than that of the hydrogel without vertically aligned channels (68.6%). Furthermore, the as-formed reactive oxygen species effectively kill Gram-positive and Gram-negative bacterial in the source water, achieving the all-round water purification. In an outdoor experiment, after 11 h of sunlight irradiation, the tetracycline degradation efficiency and freshwater production of the PCH evaporator rise to 99.0% and 6.2 kg m-2, respectively. This work highlights the novel biomimetic approach to fabricate multifunctional photothermal materials for simultaneous freshwater production and polluted-water remediation.

Comparison of ARIMA and LSTM in Forecasting the Incidence of HFMD Combined and Uncombined with Exogenous Meteorological Variables in Ningbo, China.

BACKGROUND: This study intends to identify the best model for predicting the incidence of hand, foot and mouth disease (HFMD) in Ningbo by comparing Autoregressive Integrated Moving Average (ARIMA) and Long Short-Term Memory Neural Network (LSTM) models combined and uncombined with exogenous meteorological variables. METHODS: The data of daily HFMD incidence in Ningbo from January 2014 to November 2017 were set as the training set, and the data of December 2017 were set as the test set. ARIMA and LSTM models combined and uncombined with exogenous meteorological variables were adopted to fit the daily incidence of HFMD by using the data of the training set. The forecasting performances of the four fitted models were verified by using the data of the test set. Root mean square error (RMSE) was selected as the main measure to evaluate the performance of the models. RESULTS: The RMSE for multivariate LSTM, univariate LSTM, ARIMA and ARIMAX (Autoregressive Integrated Moving Average Model with Exogenous Input Variables) was 10.78, 11.20, 12.43 and 14.73, respectively. The LSTM model with exogenous meteorological variables has the best performance among the four models and meteorological variables can increase the prediction accuracy of LSTM model. For the ARIMA model, exogenous meteorological variables did not increase the prediction accuracy but became the interference factor of the model. CONCLUSIONS: Multivariate LSTM is the best among the four models to fit the daily incidence of HFMD in Ningbo. It can provide a scientific method to build the HFMD early warning system and the methodology can also be applied to other communicable diseases.

Daily mean temperature and HFMD: risk assessment and attributable fraction identification in Ningbo China.

BACKGROUND: Hand, foot, and mouth disease (HFMD) remains a significant public health issue, especially in developing countries. Many studies have reported the association between environmental temperature and HFMD. However, the results are highly heterogeneous in different regions. In addition, there are few studies on the attributable risk of HFMD due to temperature. OBJECTIVES: The study aimed to assess the association between temperature and HFMD incidence and to evaluate the attributable burden of HFMD due to temperature in Ningbo China. METHODS: The research used daily incidence of HFMD from 2014 to 2017 and distributed lag non-linear model (DLNM) to investigate the effects of daily mean temperature (Tmean) on HFMD incidence from lag 0 to 30 days, after controlling potential confounders. The lag effects and cumulative relative risk (CRR) were analyzed. Attributable fraction (AF) of HFMD incidence due to temperature was calculated. Stratified analysis by gender and age were also conducted. RESULTS: The significant associations between Tmean and HFMD incidence were observed in Ningbo for lag 0-30. Two peaks were observed at both low (5-11 °C) and high (16-29 °C) temperature scales. For low temperature scale, the highest CRR was 2.22 (95% CI: 1.61-3.07) at 7 °C on lag 0-30. For high temperature scale, the highest CRR was 3.54 (95% CI: 2.58-4.88) at 24 °C on lag 0-30. The AF due to low and high temperature was 5.23% (95% CI: 3.10-7.14%) and 39.55% (95% CI: 30.91-45.51%), respectively. There was no significant difference between gender- and age-specific AFs, even though the school-age and female children had slightly higher AF values. CONCLUSIONS: The result indicates that both high and low temperatures were associated with daily incidence of HFMD, and more burdens were caused by heat in Ningbo.

Mass production of hierarchically porous carbon nanosheets by carbonizing "real-world" mixed waste plastics toward excellent-performance supercapacitors.

Recently, sustainable development and serious energy crisis called for appropriate managements for the large number of municipal and industrial waste plastics as well as the development of low-cost, advanced materials for energy storage. However, the complexity of waste plastics significantly hampers the application of ever used methods, and little attention is paid to the utilization of waste plastics-derived carbon in energy storage. Herein, porous carbon nanosheets (PCNSs) was produced by catalytic carbonization of "real-world" mixed waste plastics on organically-modified montmorillonite (OMMT) and the subsequent KOH activation. PCNSs was featured on hierarchically micro-/mesoporous structures with the pore size distribution centered on 0.57, 1.42 and 3.63 nm and partially exfoliated graphitic layers, and showed a high specific surface area of 2198 m2 g-1 and a large pore volume of 3.026 cm3 g-1. Benefiting from these extraordinary properties, PCNSs displayed a superior performance for supercapacitors with high specific capacitances approaching 207 and 120 F g-1 at a current density of 0.2 A g-1 in aqueous and organic electrolytes, respectively. Importantly, when the current density increased to 10 A g-1, the specific capacitances remained at 150 F g-1 (72.5%) and 95 F g-1 (79.2%) in aqueous and organic electrolytes, respectively. The outstanding rate capability of PCNSs was in sharp contrast to the performance of traditional activated carbons. This work not only provides a potential way to recycle mixed waste plastics, but also puts forward a facile sustainable approach for the large-scale production of PCNSs as a promising candidate for supercapacitors.