Facile and Widely Applicable Route to Self-Adaptive Emissivity Modulation: Energy-Saving Demonstration with Transparent Wood.

The cooling power provided by radiative cooling is unwanted during cold hours. Therefore, self-adaptive regulation is desired for radiative cooling, especially in all-weather applications. However, current routes for radiative cooling regulation are constrained by substrates and complicated processing. Here, self-adaptive radiative cooling regulation on various potential substrates (transparent wood, PET, normal glass, and cement) was achieved by a Fabry-Perot structure consisting of a silver nanowires (AgNWs) bottom layer, PMMA spacer, and W-VO2 top layer. The emissivity-modulated transparent wood (EMTW) exhibits an emissivity contrast of 0.44 (ε8-13-L = ∼0.19 and ε8-13-H = ∼0.63), which thereby yields considerable energy savings across different climate zones. The emissivity contrast can be adjusted by varying the spinning parameters during the deposition process. Positive emissivity contrast was also achieved on three other industrially relevant substrates via this facile and widely applicable route. This proves the great significance of the approach to the promotion and wide adoption of radiative cooling regulation concept in the built environment.

Nanoarchitectonics toward Full Coverage of CdZnS Nanospheres by Layered Double Hydroxides for Enhanced Visible-Light-Driven H2 Evolution.

Nanoarchitectonics of semiconductors shed light on efficient photocatalytic hydrogen evolution by precisely controlling the surface microenvironment of cocatalysts. Taking cadmium zinc sulfide (CZS) nanoparticles as a target, the spontaneous modifications are conducted by interactions between surface Cd2+ /Zn2+ atoms and thiol groups in thioglycolic acid. The capping ligand impacts the semiconductor surface with a negative electronic environment, contributing to the full coverage of CZS by nickel-cobalt hydroxides (NiCo-LDHs) cocatalysts. The obtained core-shell CZS@NiCo-LDHs, possessing a shell thickness of ≈20 nm, exhibits a distinguished topology (SBET  = 87.65m2  g-1 ), long surface carrier lifetime, and efficient charge-hole separation. Further photocatalytic hydrogen evaluation demonstrates an enhanced H2 evolution rate of 18.75 mmol g-1  h-1 with an apparent quantum efficiency of 16.3% at 420 nm. The recorded catalytic performance of the core-shell sample is 44.6 times higher than that of pure CZS nanospheres under visible light irradiation. Further density functional theory simulations indicate that sulfur atoms play the role of charge acceptor and surface Ni/Co atoms are electron donors, as well as a built-in electric field effect can be established. Altogether, this work takes advantage of strong S affinity from surface metal atoms, revealing the interfacial engineering toward improved visible-light-driven photocatalytic hydrogen evolution (PHE) activity.

Biomimetic Multifunctional Graphene-Based Coating for Thermal Management, Solar De-Icing, and Fire Safety: Inspired from the Antireflection Nanostructure of Compound Eyes.

Due to the ubiquitous and inexhaustible solar source, photothermal materials have gained considerable attention for their potential in heating and de-icing. Nevertheless, traditional photothermal materials, exemplified by graphene, frequently encounter challenges emanating from their elevated reflectance. Inspired by ocular structures, this study uses the Fresnel equation to enhance the photo-thermal conversion efficiency of graphene by introducing a polydimethylsiloxane (PDMS)/silicon dioxide (SiO2) coating, which reduces the light reflectance (≈20%) through destructive interference. The designed coating achieves an equilibrium temperature of ≈77 °C at one sun and a quick de-icing in ≈65 s, all with a thickness of 5 µm. Simulations demonstrate that applying this coating to high-rise buildings results in energy savings of ≈31% in winter heating. Furthermore, the combination of PDMS/SiO2 and graphene confers a notable enhancement in thermal stability through a synergistic flame-retardant mechanism, effectively safeguarding polyurethane against high temperatures and conflagrations, leading to marked reduction of 58% and 28% in heat release rate and total heat release. This innovative design enhances the photo-thermal conversion, de-icing function, and flame retardancy of graphene, thereby advancing its applications in outdoor equipment, high-rise buildings, and aerospace vessels.

Chip-level Ce:GdYAG ceramic phosphors with excellent chromaticity parameters for high-brightness white LED device.

Development of ceramic phosphors (CPs) featuring small volume and high efficacy is crucial for miniaturization of white LEDs and their integration in solid state lighting. In this study, the chip-level 2.5×2.5 mm Ce:GdYAG CPs with different thicknesses were packaged to the blue chips, and their luminous characteristics were analyzed under the different radiant flux. Notably, when thickness of the CPs was 1.4 mm, a luminous flux of 2000 lm, a correlated color temperature (CCT) of 6266 K and a color rendering index (CRI) of 70 were obtained under 11.0 W blue power (1.76 W/mm2) excitation. Phenomenon of colorimetric drift was explained simultaneously. These results indicate that Ce:GdYAG CPs is a promising candidate for automotive lighting and high-speed rail lighting.

Slow Dynamics of the Spin-Crossover Process in an Apparent High-Spin Mononuclear FeII Complex.

A mononuclear FeII complex that shows a high-spin (S=2) paramagnetic behavior at all temperatures (with standard temperature-scan rates, ≈1 K min-1 ) has, in fact, a low-spin (S=0) ground state below 100 K. This low-spin state is not easily accessible due to the extremely slow dynamics of the spin-crossover process-a full relaxation from the metastable high-spin state to the low-spin ground state takes more than 5 h below 80 K. Bidirectional photo-switching of the FeII state is achieved reproducibly by two selective irradiations (at 530-590 and 830-850 nm). The slow dynamics of the spin-crossover and the strong structural cooperativity result in a remarkably wide 95-K hysteresis loop induced by both temperature and selected light stimuli.

[The Effect of Ambient Temperature on Human Head's Surface Skin Temperature].

It is important to understand heat loss from human head because human head produces much heat for its high metabolism, it also functions as a heat radiator to keep body heat balance. Heat loss from human head is closely related to its skin temperature. Therefore, skin surface temperature of human head changes with ambient temperature is studied. In this research, several positions were sampled and the advanced infrared detectors (the infrared thermal imager and the infrared thermometer) were used as tools for measurement. For the sake of comparison, the young volunteers were grouped into the boys team and the girls team. Results showed that, firstly, between the groups, there was only a little difference in that girls' head temperature was a little higher; secondly, head temperature of either girls or boys rises with air temperature till about 30 ℃; and thirdly, exercise has only a little effect on the head temperature variation. This research is practical for further investigation on head heat flow and referential for health diagnosing by comparing the data recorded in this experiment.

[Object Separation from Medical X-Ray Images Based on ICA].

X-ray medical image can examine diseased tissue of patients and has important reference value for medical diagnosis. With the problems that traditional X-ray images have noise, poor level sense and blocked aliasing organs, this paper proposes a method for the introduction of multi-spectrum X-ray imaging and independent component analysis (ICA) algorithm to separate the target object. Firstly image de-noising preprocessing ensures the accuracy of target extraction based on independent component analysis and sparse code shrinkage. Then according to the main proportion of organ in the images, aliasing thickness matrix of each pixel was isolated. Finally independent component analysis obtains convergence matrix to reconstruct the target object with blind separation theory. In the ICA algorithm, it found that when the number is more than 40, the target objects separate successfully with the aid of subjective evaluation standard. And when the amplitudes of the scale are in the [25, 45] interval, the target images have high contrast and less distortion. The three-dimensional figure of Peak signal to noise ratio (PSNR) shows that the different convergence times and amplitudes have a greater influence on image quality. The contrast and edge information of experimental images achieve better effects with the convergence times 85 and amplitudes 35 in the ICA algorithm.

Fluorine-free nanoparticle coatings on cotton fabric: comparing the UV-protective and hydrophobic capabilities of silica vs. silica-ZnO nanostructures.

Robust, hydrophobic woven cotton fabrics were obtained through the sol-gel dip coating of two different nanoparticle (NP) architectures; silica and silica-ZnO. Water repellency values as high as 148° and relatively low tilt angles for fibrous fabrics (12°) were observed, without the need for fluorinated components. In all cases, this enhanced functionality was achieved with the broad retention of water vapor permeability characteristics, i.e., less than 10% decrease. NP formation routes indicated direct bonding interactions in both the silica and silica-ZnO structures. The physico-chemical effects of NP-compatibilizer (i.e., polydimethoxysilane (PDMS) and n-octyltriethoxysilane (OTES) at different ratios) coatings on cotton fibres indicate that compatibilizer-NP interactions are predominantly physical. Whenever photoactive ZnO-containing additives were used, there was a minor decrease in hydrophobic character, but order of magnitude increases in UV-protective capability (i.e., UPF > 384); properties which were absent in non-ZnO-containing samples. Such water repellency and UPF capabilities were stable to both laundering and UV-exposure, resisting the commonly encountered UV-induced wettability transitions associated with photoactive ZnO. These results suggest that ZnO-containing silica NP coatings on cotton can confer both excellent and persistent surface hydrophobicity as well as UV-protective capability, with potential uses in wearables and functional textiles applications.

Perovskite Nanocrystals Induced Core-Shell Inorganic-Organic Nanofibers for Efficient Energy Harvesting and Self-Powered Monitoring.

The emerging field of wearable electronics requires power sources that are flexible, lightweight, high-capacity, durable, and comfortable for daily use, which enables extensive use in electronic skins, self-powered sensing, and physiological health monitoring. In this work, we developed the core-shell and biocompatible Cs2InCl5(H2O)@PVDF-HFP nanofibers (CIC@HFP NFs) by one-step electrospinning assisted self-assembly method for triboelectric nanogenerators (TENGs). By adopting lead-free Cs2InCl5(H2O) as an inducer, CIC@HFP NFs exhibited ß-phase-enhanced and self-aligned nanocrystals within the uniaxial direction. The interface interaction was further investigated by experimental measurements and molecular dynamics, which revealed that the hydrogen bonds between Cs2InCl5(H2O) and PVDF-HFP induced automatically well-aligned dipoles and stabilized the ß-phase in the CIC@HFP NFs. The TENG fabricated using CIC@HFP NFs and nylon-6,6 NFs exhibited significant improvement in output voltage (681 V), output current (53.1 µA) and peak power density (6.94 W m-2), with the highest reported output performance among TENGs based on halide-perovskites. The energy harvesting and self-powered monitoring performance were further substantiated by human motions, showcasing its ability to charge capacitors and effectively operate electronics such as commercial LEDs, stopwatches, and calculators, demonstrating its promising application in biomechanical energy harvesting and self-powered sensing.

Noble metal-free ternary cobalt-nickel phosphides for enhanced photocatalytic dye-sensitized hydrogen evolution and catalytic mechanism investigation.

Transition metal phosphides have emerged as compelling alternatives to noble metal catalysts for photocatalytic hydrogen evolution, owing to their high efficiency, stability, ease of preparation, and low-cost-effectiveness. This study investigates a series of binary and ternary phosphides predominantly composed of cobalt and nickel employed for photocatalytic dye-sensitized hydrogen evolution. Under the optimal dye-to-catalyst mass ratio, CoNiP exhibited the highest hydrogen evolution activity (12.96 mmol g-1 h-1), demonstrating more significant and satisfactory performance than a variety of other reported materials. This can be attributed to the high conductivity and low hydrogen evolution overpotential of phosphides, which result from their metallic characteristics and the presence of free electrons, which promote efficient electron transfer between the catalyst and sensitizer. Density functional theory calculations revealed that the cobalt incorporation into the binary phosphides causes a negative shift in the average d-band center for CoNiP, weakening the adsorption affinity of the catalyst towards H2 molecules, thus effectively improving the hydrogen evolution rate compared to the pure binary phosphides. This work provides valuable insights for the development of low-cost and high-performance ternary phosphide photocatalysts.

Reducing the Surface Tension of Zn Anodes by an Abietic Acid Layer for High Redox Kinetics and Reversibility.

Aqueous zinc batteries are appealing devices for cost-effective and environmentally sustainable energy storage. However, the critical issues of uncontrolled dendrite propagation and side reactions with Zn anodes have hindered their practical applications. Inspired by the functions of the rosin flux in soldering, an abietic acid (ABA) layer is fabricated on the surface of Zn anodes (ABA@Zn). The ABA layer protects the Zn anode from corrosion and the concomitant hydrogen evolution reaction. It also facilitates fast interfacial charge transfer and horizontal growth of the deposited Zn by reducing the surface tension of the Zn anode. Consequently, promoted redox kinetics and reversibility are simultaneously achieved by the ABA@Zn. It demonstrates stable Zn plating/stripping cycling over 5100 h and a high critical current of 8.0 mA cm-2. Moreover, the assembled ABA@Zn|(NH4)2V6O16 full cell delivers outstanding long-term cycling stability with an 89% capacity retention after 3000 cycles. This work provides a straightforward yet effective solution to the key issues of aqueous zinc batteries.

Ultra-light-weight, anti-flammable and water-proof cellulosic aerogels for thermal insulation applications.

Cellulosic aerogels (CNF) are considered naturally available thermal insulating materials as substitutes for conventional polymeric aerogels owing to their extensive sources, low density, low thermal conductivity, sustainability and biodegradability. However, cellulosic aerogels suffer from high flammability and hygroscopicity. In this work, a novel P/N-containing flame retardant (TPMPAT) was synthesized to modify cellulosic aerogels to improve their anti-flammability. TPMPAT/CNF aerogels were further modified by polydimethylsiloxane (PDMS) to enhance the water-proof characteristics. Although the addition of TPMPAT and/or PDMS slightly increased the density and thermal conductivity of the composite aerogels, those values were still comparable to the commercial polymeric aerogels. Compared with pure CNF aerogel, the cellulose aerogel modified by TPMPAT and/or PDMS had higher T-10%, T-50% and Tmax, which indicated that the modified cellulose aerogels have better thermal stability. TPMPAT modification made CNF aerogels highly hydrophilic, while TPMPAT/CNF aerogel modified by PDMS became a highly hydrophobic material with a water contact angle (WCA) of 142°. Pure CNF aerogel burned rapidly after ignition, showing a low limiting oxygen index (LOI) of 23.0% and no UL-94 grade. In contrast, both TPMPAT/CNF-30% and PDMS-TPMPAT/CNF-30% showed self-extinction behaviors with a UL-94 V-0 grade, implying high fire resistance. Combined with high anti-flammability and hydrophobicity, the ultra-light-weight cellulosic aerogels show great potential for thermal insulation applications.

A Bionic Skin for Health Management: Excellent Breathability, In Situ Sensing, and Big Data Analysis.

Developing an intelligent wearable system is of great significance to human health management. An ideal health-monitoring patch should possess key characteristics such as high air permeability, moisture-wicking function, high sensitivity, and a comfortable user experience. However, such a patch that encompasses all these functions is rarely reported. Herein, an intelligent bionic skin patch for health management is developed by integrating bionic structures, nano-welding technology, flexible circuit design, multifunctional sensing functions, and big data analysis using advanced electrospinning technology. By controlling the preparation of nanofibers and constructing bionic secondary structures, the resulting nanofiber membrane closely resembles human skin, exhibiting excellent air/moisture permeability, and one-side sweat-wicking properties. Additionally, the bionic patch is endowed with a high-precision signal acquisition capabilities for sweat metabolites, including glucose, lactic acid, and pH; skin temperature, skin impedance, and electromyographic signals can be precisely measured through the in situ sensing electrodes and flexible circuit design. The achieved intelligent bionic skin patch holds great potential for applications in health management systems and rehabilitation engineering management. The design of the smart bionic patch not only provides high practical value for health management but also has great theoretical value for the development of the new generation of wearable electronic devices.

Guanidine-containing double-network silks with enhanced tensile and antibacterial property.

The bacterial infection of surgical wounds results in prolonged hospitalization and even death of patients, calling for antibacterial function in modern suture products. To tackle this challenge, cationic guanidine-containing copolymer was synthesized, exhibiting antibacterial potency over 5 log reduction against both Gram-positive S. aureus and Gram-negative E. coli. Furthermore, we developed a double-network silk suture by integrating a guanidine-containing copolymer network into the silk fibroin network. This suture exhibited biocidal activity against S. aureus and E. coli, and superior strength compared to the commercial product in both dry and wet conditions. These results may bring general benefits to public health and medical equipment sustainability.

A facile approach to obtain super-hydrophobicity for cotton fiber fabrics.

It is a challenging task to directly apply emulsified silicone oil to the surface of cotton fabric to obtain superhydrophobic properties. In this work, a temperature-responsive microgel was first synthesized and the particle size and distribution of the microgel, thermo-responsiveness, and hydrophobicity of the microgel membrane were investigated. Then, through an emulsifying PMHS/water system with microgels as a Pickering emulsifier, a series of Pickering emulsions were obtained. The results showed that the emulsion had the best stability when the microgel content was 2.14 wt% and the mass ratio of PMHS/water was 3/7. The optical microscopy showed that the oil phase could be uniformly dispersed in aqueous solution, and the liquid phase particle size was about 10-22 µm. And stratification of the Pickering emulsion did not occur when placed at room temperature for over one month. Finally, when the addition of Pickering emulsion is 50 g L-1 and the rolling rate is 80%, through a simple two-dip-two-padding treatment, a cotton fabric can obtain the superhydrophobic effect with a static contact angle of 149.6° at 25 °C and 156.4° at 45 °C. The development of this work provides a simple method to make cotton fabric obtain superhydrophobic effects.

An Intelligent Wearable Filtration System for Health Management.

To develop intelligent wearable protection systems is of great significance to human health engineering. An ideal intelligent air filtration system should possess reliable filtration efficiency, low pressure drop, healthcare monitoring function, and man-machine interactive capability. However, no existing intelligent protection system covers all these essential aspects. Herein, we developed an intelligent wearable filtration system (IWFS) via advanced nanotechnology and machine learning. Based on the triboelectric mechanism, the fabricated IWFS exhibits a long-lasting high particle filtration efficiency and bacteria protection efficiency of 99% and 100%, respectively, with a low-pressure drop of 5.8 mmH2O. Correspondingly, the charge accumulation of the optimized IWFS (87 nC) increased to 3.5 times that of the pristine nanomesh, providing a significant enhancement of the particle filtration efficiency. Theoretical principles, including the enhancement of the ß-phase and the lower surface potential of the modified nanomesh, were quantitatively investigated by molecular dynamics simulation, band theory, and Kelvin probe force microscopy. Furthermore, we endowed the IWFS with a healthcare monitoring function and man-machine interactive capability through machine learning and wireless transmission technology. Crucial physiological signals of people, including breath, cough, and speaking signals, were detected and classified, with a high recognition rate of 92%; the fabricated IWFS can collect healthcare data and transmit voice commands in real time without hindrance by portable electronic devices. The achieved IWFS not only has practical significance for human health management but also has great theoretical value for advanced wearable systems.

Self-Healable and Super-Tough Double-Network Hydrogel Fibers from Dynamic Acylhydrazone Bonding and Supramolecular Interactions.

Macroscopic hydrogel fibers are highly desirable for smart textiles, but the fabrication of self-healable and super-tough covalent/physical double-network hydrogels is rarely reported. Herein, copolymers containing ketone groups were synthesized and prepared into a dynamic covalent hydrogel via acylhydrazone chemistry. Double-network hydrogels were constructed via the dynamic covalent crosslinking of copolymers and the supramolecular interactions of iota-carrageenan. Tensile tests on double-network and parental hydrogels revealed the successful construction of strong and tough hydrogels. The double-network hydrogel precursor was wet spun to obtain macroscopic fibers with controlled drawing ratios. The resultant fibers reached a high strength of 1.35 MPa or a large toughness of 1.22 MJ/m3. Highly efficient self-healing performances were observed in hydrogel fibers and their bulk specimens. Through the simultaneous healing of covalent and supramolecular networks under acidic and heated conditions, fibers achieved rapid and near-complete healing with 96% efficiency. Such self-healable and super-tough hydrogel fibers were applied as shape memory fibers for repetitive actuating in response to water, indicating their potential in intelligent fabrics.

Charge-controllable mussel-inspired magnetic nanocomposites for selective dye adsorption and separation.

Magnetic polydopamine (PDA) nanocomposites were prepared with a facile and sustainable synthetic method. The as-synthesized polymer-based hybrid composites inherited the intrinsic adhesiveness contributed by catechol and amino moieties of PDA as well as the magnetic property of Fe3O4. With the unique properties of PDA, the surface charges of Fe3O4@PDA could be easily tuned by pH for smart adsorption-desorption behaviors. Four commercially available dyestuffs including crystal violet, rhodamine B, direct blue 71 and orange G with different structures and surface charges in solution were selected to investigate the adsorption ability and universality of Fe3O4@PDA in wastewater treatment. It was found that the nanocomposites could successfully adsorb these cationic and anionic dyes under suitable pH conditions. This confirmed the ability of the nanoadsorbents for the removal of common textile dyes. The dispersed magnetic nanoadsorbents also demonstrated the ease of collection from dye mixtures, and the possibility of reusing them for several cycles. Selective dye separation was found to be achievable via simple charge control without large consumption of organic solvent and energy. These bio-inspired nanocomposite adsorbents have shown high potential in wastewater treatment and selective recovery of dye waste, especially for wastewater containing ionic dyes.

Fabrication of Highly Efficient Flame-Retardant and Fluorine-Free Superhydrophobic Cotton Fabric by Constructing Multielement-Containing POSS@ZIF-67@PDMS Micro-Nano Hierarchical Coatings.

The facile construction of a cotton fabric with excellent flame-retardant and water-proof abilities is of great interest for multitask requirements. Herein, a nonfluorine, highly efficient, and cost-effective multifunctional cotton fabric was fabricated via sequentially depositing a novel multielement-containing flame-retardant phosphorylated octa-aminopropyl POSS (PPA-POSS) and a fluorine-free superhydrophobic coating of zeolitic imidazolate framework-67@poly(dimethylsiloxane) (ZIF-67@PDMS). Influences of the PPA-POSS concentration and ZIF-67@PDMS formula on the fire retardancy and water repellency of treated cotton were systematically investigated. The optimized flame-retardant sample CTF3 with 6.2 wt % PPA-POSS exhibited a high limiting oxygen index (LOI) of 34% and self-extinguishing ability. CTF3 was further modified with a properly formulated superhydrophobic ZIF-67@PDMS coating. CTF3-PHB2 displayed enhanced thermal stability, flame retardancy, and outstanding superhydrophobicity. Thermogravimetric analysis (TGA) results demonstrated that CTF3-PHB2 presented a high char residue of 35.9%, which was 220.5% higher than that of the control cotton (11.2%). More importantly, the heat release rate (HRR), total heat release (THR), and average effective heat of combustion (av-EHC) values of CTF3-PHB2 were significantly reduced by 51.4, 56.2, and 68.4%, respectively, compared with those of a pure cotton fabric. Moreover, CTF3-PHB2 showed superhydrophobicity (WCA > 159.3°) and good mechanical abrasion resistance. In addition, CTF3-PHB2 also showed protective abilities such as antifouling, self-cleaning, and water/oil separation performances even for strong acid/alkali mixtures. Thereby, it is believed that the PPA-POSS@ZIF-67@PDMS coating is promising for application in multifunctional textile materials.

Bioinspired Photo-Cross-Linking of Stretched Solid Silks for Enhanced Strength.

In this study, solid fibroin fibers (FFs) were directly cross-linked by employing a ruthenium-mediated redox pair under visible light at room temperature for the first time. The chemical cross-link through dityrosine connection was confirmed by Fourier-transform infrared (FTIR) spectroscopy, fluorescence spectra, and a solubility test. The resultant cross-link density of fibers was calculated based on their swelling ratio evaluation in LiBr solution. Further applying stretch to the fibers during irradiation increased the fiber strength to higher values. The break stress and Young's modulus of photo-cross-linked 15% stretch FFs reached a 60-90% increase in comparison to the original FFs in dry and wet conditions. This approach constitutes an easy and straightforward strategy for strengthening FFs, which is scalable industrially to enhance FFs in a wide range of applications.