Self-Encapsulation of High-Entropy Alloy Nanoparticles inside Carbonized Wood for Highly Durable Electrocatalysis.

High-entropy alloy nanoparticles (HEAs) show great potential in emerging electrocatalysis due to their combination and optimization of multiple elements. However, synthesized HEAs often exhibit a weak interface with the conductive substrate, hindering their applications in long-term catalysis and energy conversion. Herein, a highly active and durable electrocatalyst composed of quinary HEAs (PtNiCoFeCu) encapsulated inside the activated carbonized wood (ACW) is reported. The self-encapsulation of HEAs is achieved during Joule heating synthesis (2060 K, 2 s) where HEAs naturally nucleate at the defect sites. In the meantime, HEAs catalyze the deposition of mobile carbon atoms to form a protective few-layer carbon shell during the rapid quenching process, thus remarkably strengthening the interface stability between HEAs and ACW. As a result, the HEAs@ACW shows not only favorable activity with an overpotential of 7 mV at 10 mA cm-2 for hydrogen evolution but also negligible attenuation during a 500 h stability test, which is superior to most reported electrocatalysts. The design of self-encapsulated HEAs inside ACW provides a critical strategy to enhance both activity and stability, which is also applicable to many other energy conversion technologies.

Programmable, Changeable, Origami Cellulose Films for Magnetically Controllable Soft Robots.

Magnetic soft robots composed of stimuli-responsive materials are promising for biomedical engineering applications; however, typical responsive materials are fabricated with nondegradable polymeric substrates. In this study, we report a flexible, biodegradable, and magnetically sensitive cellulose film (M-film) that can be utilized for magnetically controllable soft robots (M-robots) with programmable locomotion, cargo delivery, and remote wireless operation functions. The M-film with good foldability, origami, and magnetic properties is synthesized by a simple paper-making process using cellulose nanofibers, additive sodium alginate, and BaFe12O19 particles. Through the following origami-magnetization process, the M-robot with multimodal movements is designed: climbing over the obstacles in the walking environment; additionally, this process can complete various cargo transport tasks by clawing, rolling, and flipping. This approach expands the precise controllability and manipulability of environmentally friendly cellulose nanomaterials beyond the known applications and opens the prospects of their implementation in stimuli-responsive robots, wireless control electronics, and intelligent devices.

Magnetic Heating Amorphous NiFe Hydroxide Nanosheets Encapsulated Ni Nanoparticles@Wood Carbon to Boost Oxygen Evolution Reaction Activity.

The oxygen evolution reaction (OER) has significant effects on the water-splitting process and rechargeable metal-air batteries; however, the sluggish reaction kinetics caused by the four-electron transfer process for transition metal catalysts hinder large-scale commercialization in highly efficient electrochemical energy conversion devices. Herein, a magnetic heating-assisted enhancement design for low-cost carbonized wood with high OER activity is proposed, in which Ni nanoparticles are encapsulated in amorphous NiFe hydroxide nanosheets (a-NiFe@Ni-CW) via direct calcination and electroplating. The introduction of amorphous NiFe hydroxide nanosheets optimizes the electronic structure of a-NiFe@Ni-CW, accelerating electron transfer and reducing the energy barrier in the OER. More importantly, the Ni nanoparticles located on carbonized wood can function as magnetic heating centers under the effect of an alternating current (AC) magnetic field, further promoting the adsorption of reaction intermediates. Consequently, a-NiFe@Ni-CW demonstrated an overpotential of 268 mV at 100 mA cm-2 for the OER under an AC magnetic field, which is superior to that of most reported transition metal catalysts. Starting with sustainable and abundant wood, this work provides a reference for highly effective and low-cost electrocatalyst design with the assistance of a magnetic field.

Lightweight, strong, moldable wood via cell wall engineering as a sustainable structural material.

Wood is a sustainable structural material, but it cannot be easily shaped while maintaining its mechanical properties. We report a processing strategy that uses cell wall engineering to shape flat sheets of hardwood into versatile three-dimensional (3D) structures. After breaking down wood's lignin component and closing the vessels and fibers by evaporating water, we partially re-swell the wood in a rapid water-shock process that selectively opens the vessels. This forms a distinct wrinkled cell wall structure that allows the material to be folded and molded into desired shapes. The resulting 3D-molded wood is six times stronger than the starting wood and comparable to widely used lightweight materials such as aluminum alloys. This approach widens wood's potential as a structural material, with lower environmental impact for buildings and transportation applications.

Strong, Hydrostable, and Degradable Straws Based on Cellulose-Lignin Reinforced Composites.

The huge consumption of single-use plastic straws has brought a long-lasting environmental problem. Paper straws, the current replacement for plastic straws, suffer from drawbacks, such as a high cost of the water-proof wax layer and poor water stability due to the easy delamination of the wax layer. It is therefore crucial to find a high-performing alternative to mitigate the environmental problems brought by plastic straws. In this paper, all natural, degradable, cellulose-lignin reinforced composite straws, inspired by the reinforcement principle of cellulose and lignin in natural wood are developed. The cellulose-lignin reinforced composite straw is fabricated by rolling up a wet film made of homogeneously mixed cellulose microfibers, cellulose nanofibers, and lignin powders, which is then baked in oven at 150 °C. When baked, lignin melts and infiltrates the micro-nanocellulose network, acting as a polyphenolic binder to improve the mechanical strength and hydrophobicity performance of the resulting straw. The obtained straws demonstrate several advantageous properties over paper straws, including 1) excellent mechanical performance, 2) high hydrostability, and 3) low cost. Moreover, the natural degradability of the cellulose-lignin reinforced composite straws makes them promising candidates to replace plastic straws and suggests possible substitutes for other petroleum-based plastics.

Magnetically Driven 3D Cellulose Film for Improved Energy Efficiency in Solar Evaporation.

The architecture of cellulose nanomaterials is definitized by random deposition and cannot change in response to shifting application requirements. Herein, we present a magnetic field-controlled cellulose film derived from wood that exhibits great magnetic properties and reliable tunability enabled by incorporated Fe3O4 nanoparticles and cellulose nanofibers (CNF) with a large length-diameter ratio. Fe3O4 nanoparticles are dispersed in suspensions of CNF so as to enhance the magnetic response. The plane magnetic CNF can be processed to form a three-dimensional (3D) flower-like structure along the magnetic induction line after applying an external magnet. Inspired by the fluidic transport in natural flowers, a bilayer structure was created using the 3D flower-like film as the solar energy receiver and natural wood as the water pathway in a solar-derived evaporation system. Compared with a planar cellulose film decorated with Fe3O4, the 3D structure design can greatly improve the evaporation rate from 1.19 to 1.39 kg m-2 h-1 and the efficiency from 76.9 to 90.6% under 1 sun. Finite element molding further reveals that the 3D structural top layer is beneficial for the formation of a gradient temperature profile and the improvement of the energy efficiency through the reduction of thermal radiation. The magnetically controlled fabrication represents a promising strategy for designing cellulose nanomaterials with a complicated structure and controllable topography, which has a wide spectrum of applications in energy storage devices and water treatment.

Air quality and the COVID-19 outbreak in China

We appreciate that Urrutia-Pereira M., et al. have reported on "COVID-19 and air pol­lution: A dangerous association."1 Research on the role of air pollution in the spread of SARS-CoV-2 is worth discussing. Air pollution refers to harmful substances that are carried in the air. When the quantity or proportion of the pollutants reaches or exceeds the environmental carrying capacity, they will change the normal state of the environment.2 With rapid economic development around the world, global pollution gradually increases. Ecological governance has become a crucial issue across the globe.3 Pollution control is also a highly debated issue between developing countries and developed countries; China too has an environmental pollution control problem.4 China began to pay attention to the question of pollution control and its preven­tion methods early on. The Chinese government has formulated many policies in this respect. However, these measures did not improve the environment. At the end of 2019, the COVID-19 epidemic broke in Wuhan, China.5 The Chinese government has taken a series of measures to control the outbreak. Wuhan was locked down on January 23, 2020, and people's travel was restricted. We downloaded the daily air pollution parameters of 367 cities around China from the China Meteorological Administration website (http://data.cma.cn/). Records covered the periods between January 23, 2019 and March 23, 2019; November 22, 2019 and January 22, 2020; and January 23, 2020 and March 23, 2020. Pollution severity was divided into quartiles according to the air quality index (AQI). The AQI was calculated using the con­centration of the following six pollutants: PM10, PM2.5, CO, NO2, SO2, and O3. An AQI of 0-100 indicates no pollution, 101-150 indicates mild pollution, 151-200 indicates moderate pollution, and AQI > 200 indicates severe pollution (USEPA 2013, http://www.Gpo.gov/). We found a significant improvement in air quality across China as a result of the reduction

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In Situ Lignin Modification toward Photonic Wood.

Lignin serves as a binder that forms strong matrices of the cell walls of wood. However, it has many photolabile chromophore groups that create a monotonic brownish color and make wood susceptible to photodegradation. Herein, a new strategy is reported for modifying lignin using an in situ, rapid, and scalable process that involves the photocatalytic oxidation of native lignin in wood by H2 O2 and UV light. The reaction selectively eliminates lignin's chromophores while leaving the aromatic skeleton intact, thus modulating the optical properties of wood. The resulting "photonic wood" retains ≈80% of its original lignin content, which continues to serve as a strong binder and water-proofing agent. As a result, photonic wood features a much higher mechanical strength in a wet environment (20-times higher tensile strength and 12-times greater compression resistance), significant scalability (≈2 m long sample), and largely reduced processing times (1-6.5 h vs 4-14 h) compared with delignification methods. Additionally, this in situ lignin-modified wood structure is easily patterned through a photocatalytic oxidation process. This photocatalytic production of photonic wood paves the way for the large-scale manufacturing of sustainable biosourced functional materials for a range of applications, including energy-efficient buildings, optical management, and fluidic, ionic, electronic, and optical devices.

Associations between air pollution and outpatient visits for arrhythmia in Hangzhou, China.

BACKGROUND: Arrhythmia is a common cardiovascular event that is associated with increased cardiovascular health risks. Previous studies that have explored the association between air pollution and arrhythmia have obtained inconsistent results, and the association between the two in China is unclear. METHODS: We collected daily data on air pollutants and meteorological factors from 1st January 2014 to 31st December 2016, along with daily outpatient visits for arrhythmia in Hangzhou, China. We used a quasi-Poisson regression along with a distributed lag nonlinear model to study the association between air pollution and arrhythmia morbidity. RESULTS: The results of the single-pollutant model showed that each increase of 10 µg/m3 of Fine particulate matter (PM2.5), Coarse particulate matter (PM10), Sulphur dioxide (SO2), Nitrogen dioxide (NO2), and Ozone (O3) resulted in increases of 0.6% (- 0.9, 2.2%), 0.7% (- 0.4, 1.7%), 11.9% (4.5, 19.9%), 6.7% (3.6, 9.9%), and - 0.9% (- 2.9, 1.2%), respectively, in outpatient visits for arrhythmia; each increase of 1 mg/m3 increase of carbon monoxide (CO) resulted in increase of 11.3% (- 5.9, 31.6%) in arrhythmia. The short-term effects of air pollution on arrhythmia lasted 3 days, and the most harmful effects were observed on the same day that the pollution occurred. Results of the subgroup analyses showed that SO2 and NO2 affected both men and women, but differences between the sexes were not statistically significant. The effect of SO2 on the middle-aged population was statistically significant. The effect of NO2 was significant in both the young and middle-aged population, and no significant difference was found between them. Significant effects of air pollution on arrhythmia were only detected in the cold season. The results of the two-pollutants model and the single-pollutant model were similar. CONCLUSIONS: SO2 and NO2 may induce arrhythmia, and the harmful effects are primarily observed in the cold season. There is no evidence of PM2.5, PM10, CO and O3 increasing arrhythmia risk. Special attention should be given to sensitive populations during the high-risk period.

Highly Elastic Hydrated Cellulosic Materials with Durable Compressibility and Tunable Conductivity.

Anisotropic cellular materials with direction-dependent structure and durable mechanical properties enable various applications (e.g., nanofluidics, biomedical devices, tissue engineering, and water purification), but their widespread use is often hindered by complex and scale-limited fabrication and unsatisfactory mechanical performance. Here, inspired by the anisotropic and hierarchical material structure of tendons, we demonstrate a facile, scalable top-down approach for fabricating a highly elastic, ionically conductive, anisotropic cellulosic material (named elastic wood) directly from natural wood via chemical treatment. The resulting elastic wood demonstrates good elasticity and durable compressibility, showing no sign of fatigue after 10 000 compression cycles. The chemical treatment not only softens the wood cell walls by partially removing lignin and hemicellulose but introduces an interconnected cellulose fibril network into the wood channels. Atomistic and continuum modeling further reveals that the absorbed water can freely and reversibly move inside the elastic wood and therefore helps the elastic wood accommodate large compressive deformation and recover to its original shape upon compression release. In addition, the elastic wood showed a high ionic conductivity of up to 0.5 mS cm-1 at a low KCl concentration of 10-4 M, which can be tuned by changing the compression ratio of the material. The demonstrated elastic, mechanically robust, and ionically conductive cellulosic material combining inherited anisotropic cellular structure from natural wood and a self-formed internal gel may find a variety of potential applications in ionic nanofluidics, sensors, soft robots, artificial muscle, environmental remediation, and energy storage.

The impact of Community intervention on the time from Symptom onset to first medical contact with acute coronary syndrome.

OBJECTIVE: Patient delay in the recognition of and response to the symptoms of acute coronary syndrome (ACS) is a worldwide problem. A community education program about chest pain was implemented in China, and was aimed at providing better community intervention. In this study, the impact of this program on the time of symptom onset to the first medical contact (SO-to-FMC) in ACS patients was investigated, as was the incidence of major adverse cardiac and cerebrovascular events (MACCE) in these patients. METHODS: A total of 10 local communities were included in this study. A 9-month intensive community education program about chest pain was conducted in these communities. The data on the demographics, mode of transportation, procedures, clinical outcomes, and discharge diagnoses of all ACS patients in these communities were collected. RESULTS: The study communities had a combined population of 361,609, and all community population sizes ranged from 12,823 to 66,127. The average SO-to-FMC time of the control period was 510 min, whereas, following community intervention, the average SO-to-FMC time was 256 min (P <  0.001). Furthermore, comparative analyses revealed that, following discharge from the hospital, the 1.5-year MACCE-free survival rate was higher in the community intervention group than in the control group (95.0 % vs. 90.5 %, P =  0.025), and the 1.5-year mortality rate was lower in the community intervention group than in the control group (3.3 % vs. 6.3 %, P =  0.03). CONCLUSIONS AND PRACTICAL IMPLICATIONS: The Hangzhou Chest Pain Science Education Project(HCPSEP) was found to reduce the SO-to-FMC time and improve the outcome of ACS patients. This indicates that a scientific, educational program on chest pain can be effective in improving the knowledge and alertness of the local residents about chest pain. This type of program may be recognized and carried out in other regions.

A Strong, Tough, and Scalable Structural Material from Fast-Growing Bamboo.

Lightweight structural materials with high strength are desirable for advanced applications in transportation, construction, automotive, and aerospace. Bamboo is one of the fastest growing plants with a peak growth rate up to 100 cm per day. Here, a simple and effective top-down approach is designed for processing natural bamboo into a lightweight yet strong bulk structural material with a record high tensile strength of ≈1 GPa and toughness of 9.74 MJ m-3 . More specifically, bamboo is densified by the partial removal of its lignin and hemicellulose, followed by hot-pressing. Long, aligned cellulose nanofibrils with dramatically increased hydrogen bonds and largely reduced structural defects in the densified bamboo structure contribute to its high mechanical tensile strength, flexural strength, and toughness. The low density of lignocellulose in the densified bamboo leads to a specific strength of 777 MPa cm3 g-1 , which is significantly greater than other reported bamboo materials and most structural materials (e.g., natural polymers, plastics, steels, and alloys). This work demonstrates a potential large-scale production of lightweight, strong bulk structural materials from abundant, fast-growing, and sustainable bamboo.

Beneficial effects of green tea on age related diseases.

Green tea (Camellia sinensis, Theaceace), has been extensively studied for its putative effects in prevention of age related diseases. Here, we discuss the increasing evidence that consumption of green tea has preventative effects in obesity, hypertension, insulin resistance, type II diabetes, atherosclerosis, coronary heart disease and Metabolic Syndrome (MetS). The catechins in green tea has been found to be beneficial in obesity induced by a high-fat diet. These effects are mainly attributable to the gallate esters of catechins, (-)-epicatechin gallate (ECG) and (-)-epigallocatechin-3- gallate (EGCG).

Single-digit-micrometer thickness wood speaker.

Thin films of several microns in thickness are ubiquitously used in packaging, electronics, and acoustic sensors. Here we demonstrate that natural wood can be directly converted into an ultrathin film with a record-small thickness of less than 10 µm through partial delignification followed by densification. Benefiting from this aligned and laminated structure, the ultrathin wood film exhibits excellent mechanical properties with a high tensile strength of 342 MPa and a Young's modulus of 43.6 GPa, respectively. The material's ultrathin thickness and exceptional mechanical strength enable excellent acoustic properties with a 1.83-times higher resonance frequency and a 1.25-times greater displacement amplitude than a commercial polypropylene diaphragm found in an audio speaker. As a proof-of-concept, we directly use the ultrathin wood film as a diaphragm in a real speaker that can output music. The ultrathin wood film with excellent mechanical property and acoustic performance is a promising candidate for next-generation acoustic speakers.

A radiative cooling structural material.

Reducing human reliance on energy-inefficient cooling methods such as air conditioning would have a large impact on the global energy landscape. By a process of complete delignification and densification of wood, we developed a structural material with a mechanical strength of 404.3 megapascals, more than eight times that of natural wood. The cellulose nanofibers in our engineered material backscatter solar radiation and emit strongly in mid-infrared wavelengths, resulting in continuous subambient cooling during both day and night. We model the potential impact of our cooling wood and find energy savings between 20 and 60%, which is most pronounced in hot and dry climates.

A High-Performance Self-Regenerating Solar Evaporator for Continuous Water Desalination.

Emerging solar desalination by interfacial evaporation shows great potential in response to global water scarcity because of its high solar-to-vapor efficiency, low environmental impact, and off-grid capability. However, solute accumulation at the heating interface has severely impacted the performance and long-term stability of current solar evaporation systems. Here, a self-regenerating solar evaporator featuring excellent antifouling properties using a rationally designed artificial channel-array in a natural wood substrate is reported. Upon solar evaporation, salt concentration gradients are formed between the millimeter-sized drilled channels (with a low salt concentration) and the microsized natural wood channels (with a high salt concentration) due to their different hydraulic conductivities. The concentration gradients allow spontaneous interchannel salt exchange through the 1-2 µm pits, leading to the dilution of salt in the microsized wood channels. The drilled channels with high hydraulic conductivities thus function as salt-rejection pathways, which can rapidly exchange the salt with the bulk solution, enabling the real-time self-regeneration of the evaporator. Compared to other salt-rejection designs, the solar evaporator exhibits the highest efficiency (≈75%) in a highly concentrated salt solution (20 wt% NaCl) under 1 sun irradiation, as well as long-term stability (over 100 h of continuous operation).

Preparation of heterostructured WO3/TiO2 catalysts from wood fibers and its versatile photodegradation abilities.

A facile route was adopted to synthesize heterostructured WO3/TiO2 photocatalysts from wood fibers through a two-steps hydrothermal method and a calcination process. The prepared WO3/TiO2-wood fibers were used as photocatalysts under UV irradiation for photodegradation of rhodamine B, methylene blue and methyl orange. In calcination process, the wood fibers acted as carbon substrates to prepare the WO3/TiO2 photocatalysts with high surface area and unique morphology. Thus, the significant enhanced photodegradation efficiency of the organic pollutants with the WO3/TiO2-wood fibers under UV irradiation was obtained. The photodegradation rates are measured which confirms the highest performance of the WO3/TiO2-wood fibers after calcination in comparison to the TiO2-wood fibers after calcination and the pure WO3/TiO2 after calcination. Moreover, the photodegradation efficiency of the WO3/TiO2-wood fibers after calcination under visible light is high. Our results demonstrated that the WO3/TiO2-wood fibers after calcination are a promising candidate for wastewater treatment in practical application.

Facile Design and Fabrication of Superwetting Surfaces with Excellent Wear-Resistance.

Preparation of mechanically durable superwetting surfaces is imperative, yet challenging for the wide range of real applications where high durability is required. Mechanical wear on superwetting surfaces usually degrades weak roughness, leading to loss of functions. In this study, wear-resistant superhydrophilic/underwater superoleophobic and superhydrophobic surfaces are prepared by anchoring reinforced coatings via adhesive-swelling and adhesive-bonding processes, respectively. The results of the sandpaper abrasion (grit no. 600, 24 kPa) show that superhydrophilic nylon/SiO2 coatings and superhydrophobic polyurethane/TiO2 coatings retain their functions after suffering the abrasion distances of 70 cm and more than 1000 cm, respectively. Reinforced coatings formed by consecutive roughness and improved adhesion between coatings and substrates are responsible for repeatedly generated superwettability after exposure to mechanical stresses and demonstrated to be feasible for designing wear-resistant superwetting surfaces. Furthermore, this novel architecture of "reinforced coating with consecutive roughness + high adhesion" may demand desired coating materials and reliable coating-fixing techniques for sustaining sufficient roughness and is superior to currently existing technologies in advancing wear-resistance of superwetting surfaces.

Negative Oxygen Ions Production by Superamphiphobic and Antibacterial TiO2/Cu2O Composite Film Anchored on Wooden Substrates.

According to statistics, early in the 20th century, the proportion of positive and negative air ions on the earth is 1 : 1.2. However, after more than one century, the equilibrium state of the proportion had an obvious change, which the proportion of positive and negative air ions became 1.2 : 1, leading to a surrounding of positive air ions in human living environment. Therefore, it is urgent to adopt effective methods to improve the proportion of negative oxygen ions, which are known as "air vitamin". In this study, negative oxygen ions production by the TiO2/Cu2O-treated wood under UV irradiation was first reported. Anatase TiO2 particles with Cu2O particles were doped on wooden substrates through a two-step method and further modification is employed to create remarkable superamphiphobic surface. The effect of Cu2O particles dopant on the negative oxygen ions production of the TiO2-treated wood was investigated. The results showed that the production of negative oxygen ions was drastically improved by doping with Cu2O particles under UV irradiation. The wood modified with TiO2/Cu2O composite film after hydrophobization is imparted with superamphiphobicity, antibacterial actions against Escherichia coli, and negative oxygen ions production under UV irradiation.