Capillarity in Interfacial Liquids and Marbles: Mechanisms, Properties, and Applications.

The mechanics of capillary force in biological systems have critical roles in the formation of the intra- and inter-cellular structures, which may mediate the organization, morphogenesis, and homeostasis of biomolecular condensates. Current techniques may not allow direct and precise measurements of the capillary forces at the intra- and inter-cellular scales. By preserving liquid droplets at the liquid-liquid interface, we have discovered and studied ideal models, i.e., interfacial liquids and marbles, for understanding general capillary mechanics that existed in liquid-in-liquid systems, e.g., biomolecular condensates. The unexpectedly long coalescence time of the interfacial liquids revealed that the Stokes equation does not hold as the radius of the liquid bridge approaches zero, evidencing the existence of a third inertially limited viscous regime. Moreover, liquid transport from a liquid droplet to a liquid reservoir can be prohibited by coating the droplet surface with hydrophobic or amphiphilic particles, forming interfacial liquid marbles. Unique characteristics, including high stability, transparency, gas permeability, and self-assembly, are observed for the interfacial liquid marbles. Phase transition and separation induced by the formation of nanostructured materials can be directly observed within the interfacial liquid marbles without the need for surfactants and agitation, making them useful tools to research the interfacial mechanics.

A Cross-Plane Design for Wearable Thermoelectric Generators with High Stretchability and Output Performance.

Stretchable wearable thermoelectric (TE) generators (WTEGs) without compromising output performance for real wearables have attracted much attention recently. Herein, a 3D thermoelectric generator with biaxial stretchability is constructed on the device level. Ultraflexible inorganic Ag/Ag2 Se strips are sewn into the soft purl-knit fabric, in which the thermoelectric legs are aligned in the direction of vertical heat flux. A stable and sufficient temperature gradient of 5.2 °C across the WTEG is therefore achieved when contacted with the wrist at a room temperature of 26.3 °C. The prepared TEG generates a high power density of 10.02 W m-2 at a vertical temperature gradient of 40 K. Meanwhile, the reliable energy harvesting promises a variation of less than 10% under the biaxial stretching up to 70% strain via leveraging the combined effects of the stretchability of knit fabric and geometry of TE strips. The knit fabric-supported TEG enables a seamless conformation to the skin as well as efficient body heat harvesting, which can provide sustainable energy to low power consumption wearable electronics.

Terahertz polarization and chirality modulation induced by asymmetry inversion combining chiral metasurface and liquid crystal anisotropy.

We experimentally demonstrate a dynamic terahertz (THz) chiral device based on a composite structure of anisotropic liquid crystals (LCs) sandwiched between a bilayer metasurface. The device supports the symmetric mode and antisymmetric mode under the incidence of left- and right-circular polarized waves, respectively. The different coupling strengths of the two modes reflect the chirality of the device, and the anisotropy of the LCs can change the coupling strength of the modes, which brings tunability to the chirality of the device. The experimental results show that the circular dichroism of the device can be dynamically controlled from 28 dB to -32 dB (i.e., inversion regulation) at approximately 0.47 THz and from -32 dB to 1 dB (i.e., switching regulation) at approximately 0.97 THz. Moreover, the polarization state of the output wave is also tunable. Such flexible and dynamic manipulation of THz chirality and polarization might build an alternative pathway for complex THz chirality control, high-sensitivity THz chirality detection, and THz chiral sensing.

Improving Generalizability of Spectral Reflectance Reconstruction Using L1-Norm Penalization.

Spectral reflectance reconstruction for multispectral images (such as Weiner estimation) may perform sub-optimally when the object being measured has a texture that is not in the training set. The accuracy of the reconstruction is significantly lower without training samples. We propose an improved reflectance reconstruction method based on L1-norm penalization to solve this issue. Using L1-norm, our method can provide the transformation matrix with the favorable sparse property, which can help to achieve better results when measuring the unseen samples. We verify the proposed method by reconstructing spectral reflection for four types of materials (cotton, paper, polyester, and nylon) captured by a multispectral imaging system. Each of the materials has its texture and there are 204 samples in each of the materials/textures in the experiments. The experimental results show that when the texture is not included in the training dataset, L1-norm can achieve better results compared with existing methods using colorimetric measure (i.e., color difference) and shows consistent accuracy across four kinds of materials.

Environmentally Benign Biosynthesis of Hierarchical MOF/Bacterial Cellulose Composite Sponge for Nerve Agent Protection.

The fabrication of MOF polymer composite materials enables the practical applications of MOF-based technology, in particular for protective suits and masks. However, traditional production methods typically require organic solvent for processing which leads to environmental pollution, low-loading efficiency, poor accessibility, and loss of functionality due to poor solvent resistance properties. For the first time, we have developed a microbial synthesis strategy to prepare a MOF/bacterial cellulose nanofiber composite sponge. The prepared sponge exhibited a hierarchically porous structure, high MOF loading (up to ≈90 %), good solvent resistance, and high catalytic activity for the liquid- and solid-state hydrolysis of nerve agent simulants. Moreover, the MOF/ bacterial cellulose composite sponge reported here showed a nearly 8-fold enhancement in the protection against an ultra-toxic nerve agent (GD) in permeability studies as compared to a commercialized adsorptive carbon cloth. The results shown here present an essential step toward the practical application of MOF-based protective gear against nerve agents.

Immobilized Regenerable Active Chlorine within a Zirconium-Based MOF Textile Composite to Eliminate Biological and Chemical Threats.

The most recent global health crisis caused by the SARS-CoV-2 outbreak and the alarming use of chemical warfare agents highlight the necessity to produce efficient protective clothing and masks against biohazard and chemical threats. However, the development of a multifunctional protective textile is still behind to supply adequate protection for the public. To tackle this challenge, we designed multifunctional and regenerable N-chlorine based biocidal and detoxifying textiles using a robust zirconium metal-organic framework (MOF), UiO-66-NH2, as a chlorine carrier which can be easily coated on textile fibers. A chlorine bleaching converted the amine groups located on the MOF linker to active N-chlorine structures. The fibrous composite exhibited rapid biocidal activity against both Gram-negative bacteria (E. coli) and Gram-positive bacteria (S. aureus) with up to a 7 log reduction within 5 min for each strain as well as a 5 log reduction of SARS-CoV-2 within 15 min. Moreover, the active chlorine loaded MOF/fiber composite selectively and rapidly degraded sulfur mustard and its chemical simulant 2-chloroethyl ethyl sulfide (CEES) with half-lives less than 3 minutes. The versatile MOF-based fibrous composite designed here has the potential to serve as protective cloth against both biological and chemical threats.

Integration of Metal-Organic Frameworks on Protective Layers for Destruction of Nerve Agents under Relevant Conditions.

Metal-organic frameworks (MOFs) are promising candidates for the catalytic hydrolysis of nerve agents and their simulants. Though highly efficient, bulk water and volatile bases are often required for hydrolysis with these MOF catalysts, preventing real-world implementation. Herein we report a generalizable and scalable approach for integrating MOFs and non-volatile polymeric bases onto textile fibers for nerve agent hydrolysis. Notably, the composite material showed similar reactivity under ambient conditions compared to the powder material in aqueous alkaline solution. This represents a critical step toward a unified strategy for nerve agent hydrolysis in practical settings, which can significantly reduce the dimensions of filters and increase the efficiency of protective suits.

Scalable and Template-Free Aqueous Synthesis of Zirconium-Based Metal-Organic Framework Coating on Textile Fiber.

Organophosphonate-based nerve agents, such as VX, Sarin (GB), and Soman (GD), are among the most toxic chemicals to humankind. Recently, we have shown that Zr-based metal-organic frameworks (Zr-MOFs) can effectively catalyze the hydrolysis of these toxic chemicals for diminishing their toxicity. On the other hand, utilizing these materials in powder form is not practical, and developing scalable and economical processes for integrating these materials onto fibers is crucial for protective gear. Herein, we report a scalable, template-free, and aqueous solution-based synthesis strategy for the production of Zr-MOF-coated textiles. Among all MOF/fiber composites reported to date, the MOF-808/polyester fibers exhibit the highest rates of nerve agent hydrolysis. Moreover, such highly porous fiber composites display significantly higher protection time compared to that of its parent fabric for a mustard gas simulant, 2-chloroethyl ethyl sulfide (CEES). A decreased diffusion rate of toxic chemicals through the MOF layer can provide time needed for the destruction of the harmful species.

Lighting Deviation Correction for Integrating-Sphere Multispectral Imaging Systems.

In an integrating sphere multispectral imaging system, measurement inconsistency can arise when acquiring the spectral reflectances of samples. This is because the lighting condition can be changed by the measured samples, due to the multiple light reflections inside the integrating sphere. Besides, owing to non-uniform light transmission of the lens and narrow-band filters, the measured reflectance is spatially dependent. To deal with these problems, we propose a correction method that consists of two stages. The first stage employs a white board to correct non-uniformity and a small white patch to correct lighting deviation, both under the assumption of ideal Lambertian reflection. The second stage uses a polynomial regression model to further remove the lighting inconsistency when measuring non-Lambertian samples. The method is evaluated on image data acquired in a real multispectral imaging system. Experimental results illustrate that our method eliminates the measurement inconsistency considerably. This consequently improves the spectral and colorimetric accuracy in color measurement, which is crucial to practical applications.

Bidirectional texture function image super-resolution using singular value decomposition.

The bidirectional texture function (BTF) is widely employed to achieve realistic digital reproduction of real-world material appearance. In practice, a BTF measurement device usually does not use high-resolution (HR) cameras in data collection, considering the high equipment cost and huge data space required. The limited image resolution consequently leads to the loss of texture details in BTF data. This paper proposes a fast BTF image super-resolution (SR) algorithm to deal with this issue. The algorithm uses singular value decomposition (SVD) to separate the collected low-resolution (LR) BTF data into intrinsic textures and eigen-apparent bidirectional reflectance distribution functions (eigen-ABRDFs) and then improves the resolution of the intrinsic textures via image SR. The HR BTFs can be finally obtained by fusing the reconstructed HR intrinsic textures with the LR eigen-ABRDFs. Experimental results show that the proposed algorithm outperforms the state-of-the-art single-image SR algorithms in terms of reconstruction accuracy. In addition, thanks to the employment of SVD, the proposed algorithm is computationally efficient and robust to noise corruption.

Durable Antibacterial and Nonfouling Cotton Textiles with Enhanced Comfort via Zwitterionic Sulfopropylbetaine Coating.

A rapid, environment-friendly, and cost-effective finishing method has been developed for cotton textiles by using zwitterionic NCO-sulfopropylbetaine as the antibacterial finishing agent through covalent bond. The sulfopropylbetaine-finished cotton textile exhibits durable broad-spectrum antibacterial and nonfouling activity, improved mechanical properties, and enhanced comfort.

Spectral bidirectional texture function reconstruction by fusing multiple-color and spectral images.

Spectral bidirectional texture function (BTF) is essential for accurate reproduction of material appearance due to its nature of conveying both spatial and spectral information. A practical issue is that the acquisition of raw spectral BTFs is time-consuming. To resolve the limitation, this paper proposes a novel framework for efficient spectral BTF acquisition and reconstruction. The framework acquires red-green-blue (RGB) BTF images and just one spectral image. The full spectral BTFs are reconstructed by fusing the RGB and spectral images based on nonnegative matrix factorization (NMF). Experimental results indicate that the accuracy of spectral reflectance reconstruction is higher than that of existing algorithms. With the reconstructed spectral BTFs, the material appearance can be reproduced with high fidelity under various illumination conditions.

Channel selection for multispectral color imaging using binary differential evolution.

In multispectral color imaging, there is a demand to select a reduced number of optimal imaging channels to simultaneously speed up the image acquisition process and keep reflectance reconstruction accuracy. In this paper, the channel selection problem is cast as the binary optimization problem, and is consequently solved using a novel binary differential evolution (DE) algorithm. In the proposed algorithm, we define the mutation operation using a differential table of swapping pairs, and deduce the trial solutions using neighboring self-crossover. In this manner, the binary DE algorithm can well adapt to the channel selection problem. The proposed algorithm is evaluated on the multispectral color imaging system on both synthetic and real data sets. It is verified that high color accuracy is achievable by only using a reduced number of channels using the proposed method. In addition, as binary DE is a global optimization algorithm in nature, it performs better than the traditional sequential channel selection algorithm.

Organic liquids-responsive ß-cyclodextrin-functionalized graphene-based fluorescence probe: label-free selective detection of tetrahydrofuran.

In this study, a label-free graphene-based fluorescence probe used for detection of volatile organic liquids was fabricated by a simple, efficient and low-cost method. To fabricate the probe, a bio-based ß-cyclodextrin (ß-CD) was firstly grafted on reduced graphene surfaces effectively and uniformly, as evidenced by various characterization techniques such as Ultraviolet/Visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. The subsequent inclusion of Rhodamine B (RhB) into the inner cavities of the ß-CD grafted on the graphene surfaces was achieved easily by a solution mixing method, which yielded the graphene-based fluorescent switch-on probe. In addition, the gradual and controllable quenching of RhB by Fluorescence Resonance Energy Transfer from RhB to graphene during the process of stepwise accommodation of the RhB molecules into the ß-CD-functionalized graphene was investigated in depth. A wide range of organic solvents was examined using the as-fabricated fluorescence probe, which revealed the highest sensitivity to tetrahydrofuran with the detection limit of about 1.7 µg/mL. Some insight into the mechanism of the different responsive behaviors of the fluorescence sensor to the examined targets was also described.

Applications of waste polyethylene terephthalate (PET) based nanostructured materials: A review.

While polyethylene terephthalate (PET) has enjoyed widespread use, a large volume of plastic waste has also been produced as a result, which is detrimental to the environment. Traditional treatment of plastic waste, such as landfilling and incinerating waste, causes environmental pollution and poses risks to public health. Recycling PET waste into useful chemicals or upcycling the waste into high value-added materials can be remedies. This review first provides a brief introduction of the synthesis, structure, properties, and applications of virgin PET. Then the conversion process of waste PET into high value-added materials for different applications are introduced. The conversion mechanisms (including degradation, recycling and upcycling) are detailed. The advanced applications of these upgraded materials in energy storage devices (supercapacitors, lithium-ion batteries, and microbial fuel cells), and for water treatment (to remove dyes, heavy metals, and antibiotics), environmental remediation (for air filtration, CO2 adsorption, and oil removal) and catalysis (to produce H2, photoreduce CO2, and remove toxic chemicals) are discussed at length. In general, this review details the exploration of advanced technologies for the transformation of waste PET into nanostructured materials for various applications, and provides insights into the role of high value-added waste products in sustainability and economic development.

Recent advances in cotton fabric-based photocatalytic composites for the degradation of organic contaminants.

Cotton is one of the oldest and most widely used natural fibers in the world. It enables a wide range of applications due to its excellent moisture absorption, thermal insulation, heat resistance, and durability. Benefiting from current developments in textile technology and materials science, people are constantly seeking more comfortable, more beautiful and more versatile cotton fabrics. As the second skin of body, clothing not only provides the basic needs of wear but also increases the protection of body against different environmental stimuli. In this article, a comprehensive review is proposed regarding research activities of systematically summarise the development and research of cotton fabric-based photocatalytic composites for the degradation of organic contaminants in the area of self-cleaning, degradation of gaseous contaminants, pathogenic bacteria or viruses, and chemical warfare agents. Specifically, we begin with a brief exposition of the background and significance of cotton fabric-based photocatalytic composites. Next, a systematical review on cotton fabric-based photocatalytic composites is provided according to their mechanisms and advanced applications. Finally, a simple summary and analysis concludes the current limitations and future directions in these composites for the degradation of organic contaminants.

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.

Soft Gel Filler Embedded Elastomer with Surfactant Improved Interface for Dielectric Elastomer Actuators.

Stretchable materials are the foundation of dielectric actuators (DEAs) for artificial muscle. However, the inadequate dielectric constant of stretchable materials has always greatly limited the performance of artificial muscle. Recently, soft fillers have been proposed to improve the dielectric property and preserve the stretchability for softness, aiming to avoid the stiffening effect of traditional rigid fillers. As composites, an amount of interfacial region is generated, which remarkably affects composites' performance from dielectrics to mechanics. Herein, we demonstrate that the size effect, interfacial binding, and compatibility have a great impact on soft filler doped composites. Particularly, according to the liquid characteristics of soft fillers, we explore an interfacial modification method using surfactants. Composite breakdown strength is thus enhanced 2.2-fold from that in the control group due to the reduction of mismatch between fillers and matrix. Moreover, surfactants alleviate the well-known stiffening effect in small fillers. The area strain of the composites reaches 10.3 ± 0.4% at a low electric field of 7 MV/m, and a soft micropump is successfully assembled. These findings demonstrate a unique and combined interfacial influence of soft filler doped elastomer, which promotes the advancements of the dielectric elastomer artificial muscle.

Wetting Behavior-Induced Interfacial transmission of Energy and Signal: Materials, Mechanisms, and Applications.

Wetting behaviors can significantly affect the transport of energy and signal (E&S) through vapor, solid, and liquid interfaces, which has prompted increased interest in interfacial science and technology. E&S transmission can be achieved using electricity, light, and heat, which often accompany and interact with each other. Over the past decade, their distinctive transport phenomena during wetting processes have made significant contributions to various domains. However, few studies have analyzed the intricate relationship between wetting behavior and E&S transport. This review summarizes and discusses the mechanisms of electrical, light, and heat transmission at wetting interfaces to elucidate their respective scientific issues, technical characteristics, challenges, commonalities, and potential for technological convergence. The materials, structures, and devices involved in E&S transportation are also analyzed. Particularly, harnessing synergistic advantages in practical applications and constructing advanced, multifunctional, and highly efficient smart systems based on wetted interfaces is the aim to provide strategies.

Fibrous Zr-MOF Nanozyme Aerogels with Macro-Nanoporous Structure for Enhanced Catalytic Hydrolysis of Organophosphate Toxins.

Metal-organic frameworks (MOFs) with Lewis acid catalytic sites, such as zirconium-based MOFs (Zr-MOFs), comprise a growing class of phosphatase-like nanozymes that can degrade toxic organophosphate pesticides and nerve agents. Rationally engineering and shaping MOFs from as-synthesized powders into hierarchically porous monoliths is essential for their use in emerging applications, such as filters for air and water purification and personal protection gear. However, several challenges still limit the production of practical MOF composites, including the need for sophisticated reaction conditions, low MOF catalyst loadings in the resulting composites, and poor accessibility to MOF-based active sites. To overcome these limitations, a rapid synthesis method is developed to introduce Zr-MOF nanozyme coating into cellulose nanofibers, resulting in the formation of processable monolithic aerogel composites with high MOF loadings. These composites contain Zr-MOF nanozymes embedded in the structure, and hierarchical macro-micro porosity enables excellent accessibility to catalytic active sites. This multifaceted rational design strategy, including the selection of a MOF with many catalytic sites, fine-tuning the coating morphology, and the fabrication of a hierarchically structured monolithic aerogel, renders synergistic effects toward the efficient continuous hydrolytic detoxification of organophosphorus-based nerve agent simulants and pesticides from contaminated water.