Active Material Research Articles

PbI2 Passivation of Three Dimensional PbS Quantum Dot Superlattices Toward Optoelectronic Metamaterials.

Lead chalcogenide colloidal quantum dots are one of the most promising materials to revolutionize the field of short-wavelength infrared optoelectronics due to their bandgap tunability and strong absorption. By self-assembling these quantum dots into ordered superlattices, mobilities approaching those of the bulk counterparts can be achieved while still retaining their original optical properties. The recent literature focused mostly on PbSe-based superlattices, but PbS quantum dots have several advantages, including higher stability. In this work, we demonstrate highly ordered 3D superlattices of PbS quantum dots with tunable thickness up to 200 nm and high coherent ordering, both in-plane and along the thickness. We show that we can successfully exchange the ligands throughout the film without compromising the ordering. The superlattices as the active material of an ion gel-gated field-effect transistor achieve electron mobilities up to 220 cm2 V-1 s-1. To further improve the device performance, we performed a postdeposition passivation with PbI2, which noticeably reduced the subthreshold swing making it reach the Boltzmann limit. We believe this is an important proof of concept showing that it is possible to overcome the problem of high trap densities in quantum dot superlattices enabling their application in optoelectronic devices.

Mechanical and biochemical feedback combine to generate complex contractile oscillations in cytokinesis

The actomyosin cortex is an active material that generates force to drive shape changes via cytoskeletal remodeling. Cytokinesis is the essential cell division event during which a cortical actomyosin ring closes to separate two daughter cells. Our active gel theory predicted that actomyosin systems controlled by a biochemical oscillator and experiencing mechanical strain would exhibit complex spatiotemporal behavior. To test whether active materials invivo exhibit spatiotemporally complex kinetics, we imaged the C.elegans embryo with unprecedented temporal resolution and discovered that sections of the cytokinetic cortex undergo periodic phases of acceleration and deceleration. Contractile oscillations exhibited a range of periodicities, including those much longer periods than the timescale of RhoA pulses, which was shorter in cytokinesis than in any other biological context. Modifying mechanical feedback invivo or in silico revealed that the period of contractile oscillation is prolonged as a function of the intensity of mechanical feedback. Fast local ring ingression occurs where speed oscillations have long periods, likely due to increased local stresses and, therefore, mechanical feedback. Fast ingression also occurs where material turnover is high, invivo and in silico. We propose that downstream of initiation by pulsed RhoA activity, mechanical feedback, including but not limited to material advection, extends the timescale of contractility beyond that of biochemical input and, therefore, makes it robust to fluctuations in activation. Circumferential propagation of contractility likely allows for sustained contractility despite cytoskeletal remodeling necessary to recover from compaction. Thus, like biochemical feedback, mechanical feedback affords active materials responsiveness and robustness.

A novel closed-loop biotechnology for recovery of cobalt from a lithium-ion battery active cathode material.

In recent years, the demand for lithium-ion batteries (LIBs) has been increasing rapidly. Conventional recycling strategies (based on pyro- and hydrometallurgy) are damaging for the environment and more sustainable methods need to be developed. Bioleaching is a promising environmentally friendly approach that uses microorganisms to solubilize metals. However, a bioleaching-based technology has not yet been applied to recover valuable metals from waste LIBs on an industrial scale. A series of experiments was performed to improve metal recovery rates from an active cathode material (LiCoO2; LCO). (i) Direct bioleaching of ≤0.5 % LCO with two prokaryotic acidophilic consortia achieved >80 % Co and 90 % Li extraction. Significantly lower metal recovery rates were obtained at 30 °C than at 45 °C. (ii) In contrast, during direct bioleaching of 3 % LCO with consortia adapted to elevated LCO levels, the 30 °C consortium performed significantly better than the 45 °C consortium, solubilizing 73 and 93 % of the Co and Li, respectively, during one-step bioleaching, and 83 and 99 % of the Co and Li, respectively, during a two-step process. (iii) The adapted 30°C consortium was used for indirect leaching in a low-waste closed-loop system (with 10 % LCO). The process involved generation of sulfuric acid in an acid-generating bioreactor (AGB), 2-3 week leaching of LCO with the biogenic acid (pH 0.9), selective precipitation of Co as hydroxide, and recirculation of the metal-free liquor back into the AGB. In total, 58.2 % Co and 100 % Li were solubilized in seven phases, and >99.9 % of the dissolved Co was recovered after each phase as a high-purity Co hydroxide. Additionally, Co nanoparticles were generated from the obtained Co-rich leachates, using Desulfovibrio alaskensis, and Co electrowinning was optimized as an alternative recovery technique, yielding high recovery rates (91.1 and 73.6% on carbon felt and roughened steel, respectively) from bioleachates that contained significantly lower Co concentrations than industrial hydrometallurgical liquors. The closed-loop system was highly dominated by the mixotrophic archaeon Ferroplasma and sulfur-oxidizing bacteria Acidithiobacillus caldus and Acidithiobacillus thiooxidans. The developed system achieved high metal recovery rates and provided high-purity solid products suitable for a battery supply chain, while minimizing waste production and the inhibitory effects of elevated concentrations of dissolved metals on the leaching prokaryotes. The system is suitable for scale-up applications and has the potential to be adapted to different battery chemistries.

Bacteriophages: Natural antimicrobial bioadditives for food preservation in active packaging

Developing innovative films and coatings is paramount for extending the shelf life of numerous food products and augmenting the barrier and antimicrobial properties of food packaging materials. Many synthetic chemicals used in active packaging and food storage have the potential to leach into food, posing long-term health risks. It is imperative for active packaging materials to inherently possess biological protective properties to ensure food quality and safety throughout its storage. Bacteriophages, or simply phages, are bacteria-eating viruses that serve as promising natural biocontrol agents and antimicrobial bioadditives in food packaging materials, specifically targeting bacterial foodborne pathogens. These phages are generally recognized as safe (GRAS) by regulatory authorities for food safety applications. They exhibit targeted action against various Gram-positive and -negative foodborne pathogens, including Bacillus spp., Campylobacter spp., Escherichia coli, Listeria monocytogenes, Salmonella spp., Shigella spp., and Vibrio spp., associated with foodborne spoilage and illness without affecting the beneficial microbes. Phage cocktails can be applied directly on food surfaces, incorporated into food packaging materials, or utilized during food processing treatments. Unlike chemical agents, phage activity increases proportionally with the rise in pathogenic bacterial populations. Researchers are exploring various packaging materials to deliver phages with broad host range, stability, and viability ensuring their effectiveness in safeguarding various food systems. The effectiveness of phage immobilization or encapsulation on active food packaging materials depends on various factors, including the characteristics of polymers, the choice of solvents, the type of phage, and its loading efficiency. Factors such as the orientation of phage immobilization on substrates, pH, temperature, exposure to carbohydrates and amino acids, exopolysaccharides, lipopolysaccharides, and metals can also influence phage activity. In this review, we comprehensively discuss the various active packaging systems utilizing bacteriophages as natural biocontrols and antimicrobial bioadditives to reduce the incidence of foodborne illness and enhance consumer confidence in the safety of food products.

All solid-state lithium-ion batteries based on designed polyrotaxane-containing networks

Selecting the appropriate polymer structure for use as both a solid electrolyte and catholyte is essential for enhancing the electrochemical performance of all-solid-state lithium metal batteries. In this study, we are pioneering the customization of solid electrolyte and catholyte synthesis based on novel polyrotaxane (PRX)-containing polymer networks by altering the length of the polyether crosslinkers to tune the properties to meet specific needs of different components. On one hand, the modified PRX polymer networks based on the shorter crosslinker show good mechanical strength, high ionic conductivity (7.25 × 10−4 S cm−1) and high lithium ions transference number (0.54) at 60 °C, allowing their use as solid polymer electrolyte (SPE) self-supporting membranes. On the other hand, all-solid-state lithium-ion batteries with this SPE demonstrate a much higher initial capacity (above 160 mAh/g using LiFePO4 as active material at the cathode and lithium metal as anode), and better cycling performance when paired with longer cross-linked PRX as catholytes than the other non-customized combinations all solid lithium-ion batteries. Moreover, the cycling performance of the full cell can be further improved by incorporating different lithium salts in the electrolyte (LiTFSI) and cathode (LiClO4). This work highlights that the customized design of solid electrolytes and catholytes based on polymer networks is an efficient strategy to obtain high-performance all-solid-state lithium metal batteries

All solid-state lithium-ion batteries based on designed polyrotaxane-containing networks

Selecting the appropriate polymer structure for use as both a solid electrolyte and catholyte is essential for enhancing the electrochemical performance of all-solid-state lithium metal batteries. In this study, we are pioneering the customization of solid electrolyte and catholyte synthesis based on novel polyrotaxane (PRX)-containing polymer networks by altering the length of the polyether crosslinkers to tune the properties to meet specific needs of different components. On one hand, the modified PRX polymer networks based on the shorter crosslinker show good mechanical strength, high ionic conductivity (7.25 × 10−4 S cm−1) and high lithium ions transference number (0.54) at 60 °C, allowing their use as solid polymer electrolyte (SPE) self-supporting membranes. On the other hand, all-solid-state lithium-ion batteries with this SPE demonstrate a much higher initial capacity (above 160 mAh/g using LiFePO4 as active material at the cathode and lithium metal as anode), and better cycling performance when paired with longer cross-linked PRX as catholytes than the other non-customized combinations all solid lithium-ion batteries. Moreover, the cycling performance of the full cell can be further improved by incorporating different lithium salts in the electrolyte (LiTFSI) and cathode (LiClO4). This work highlights that the customized design of solid electrolytes and catholytes based on polymer networks is an efficient strategy to obtain high-performance all-solid-state lithium metal batteries.

Low-frequency non-reciprocal sound propagation features in thermoacoustic waveguide.

Thermoacoustic waveguides are systems of hollow tubes and thermally graded porous segments that can operate as active materials where acoustic waves receive energy from an external heat source. This work demonstrates that by adjusting the pore geometry several unique low-frequency propagation features arise from the complex-valued band structure of periodic thermoacoustic waveguides that reflect into the acoustic pressure field within finite-length systems. Numerical methods have been employed to model waveguides with porous segments constituted by cylindrical inclusions (parallel pins). In periodic structures, a critical frequency emerges where the sign of the refractive index in one direction of propagation changes, thus zero- and negative-unidirectional refractive index, unidirectional energy transport, and amplification/attenuation crossover effects may take place. On the other hand, the study of the acoustic pressure field shows that, for wave packets with either direction of propagation, finite-length waveguides may behave as active acoustic metamaterials with zero- or negative-refractive index. The acoustic pressure field in the waveguide, generated by an upstream source, may exhibit increasing amplitude and phase recovery farther away from the source, mimicking the field created by a downstream source, propagating upstream in a non-active medium.

Enhancement of electrochemical stability by molecular cation vacancies of the electrode material CH3NH3NiCl3 for lithium-ion batteries

At present, efforts are being made to find new low-cost materials for photovoltaic, optoelectronic and energy storage applications. In this regard, compounds of the halide perovskite type have been increasingly studied over the past few years. The incorporation of small cations in these compounds and their possible use in rechargeable batteries can be achieved by the electrochemical reversibility technique, where perovskites with large cations are used to obtain a new isostructural compound with smaller cations and large interstitial space or free vacancies for ionic transport. The present work studied the electrochemical reversibility of lithium-ion into CH3NH3NiCl3 (MANiCl3) active material, after the formation of MA± vacancies or interstitial spaces, taking both experimental and theoretical approaches. The material displayed an anodic behavior and an initial capacity of discharge of ca. 170 mA h/g at 0.2C (0.1 mA), a full capacity retention up to the first 25 cycles of charge–discharge, and even reached a retention of up to 80 % of initial capacity at the 80th cycle. First-principles density functional theory calculations show that the shape of the crystal lattice and volume changes of all the different phases involved in the electrochemical process are tiny, at about 3 Å3 per cell. In addition, there are no appreciable elastic contributions to the energy variation during the de-lithiation/lithiation process, indicating that memory effects are not an issue. The calculated formation energies of the lithiated structures and the open circuit voltages are −2.91 eV and 1.33 V for LinMA1-nNiCl3 and −1.41 eV and 2.91 V for Li2nMA1-nNiCl3, respectively. These findings suggest that incorporating one or, at most, to two lithium atoms is favorable for the overall stability and electrochemical performance.

Herbal medicine in the Jewish renaissance rare medical handbook The Guide to the Tree of Life (Sejfer derech ejc ha-chajim)

Ethnopharmacological relevanceThe only known copy of Sejfer derech ejc ha-chajim, an anonymous old print, is stored in the Austrian National Library in Vienna. It was written in the Yiddish Ashkenazi language and printed in 1613. The author, a Jewish physician, resided or lived in the Polish-Lithuanian Commonwealth. This rare book, although it was printed over 400 years ago, has not yet been systematically assessed in the ethnomedical context of those times.Aim of the study: A quantitative assessment of the botanical drugs and kinds of healthy diets described in The Guide is presented to recognise the medicinal, diachronic, and botanical outlines of this peculiar rarum. Materials and MethodsTo investigate various recipes describing the use of medicinal plants of Jewish culture in the former Polish-Lithuanian Commonwealth, the content of The Guide was analysed. All therapeutic uses of herbal medicines and nutritional recommendations for health were obtained by reviewing the Polish translation of the rare medical handbook. For each plant usage revealed in the text, we noted: Scientific, Common and Yiddish name of the taxon, Plant family, Part of the plant or substance used, Administration, Preparation, Primary pathology, Broad use, and Inferred pathology (ICD-11 and ICPC-3). ResultsAmong the 161 recipes, 58 plant taxa and 361 use records were recorded. Additionally, 127 mixtures with 68 plant taxa and 183 use mixture records were noted. 22 diet recipes with 19 plant taxa were also found. These data constitute three separate analyses, according to the intention of the author of The Guide. Formulations using Apiaceae were recommended primarily for gastroenterology and gynecology, while those using Rosaceae for gastroenterology, urology, and neurology. For mixtures, Lamiaceae plants are also represented and used for gastroenterology, respiratory system treatment, and gynecology. ConclusionThe medicinal knowledge described in Sejfer derech ejc ha-chajim fills a gap in contemporary knowledge regarding phyto-medical writing of the Renaissance. The Guide has a form of home first aid kit, used both for medicinal purposes and on the daily menu. In response to current challenges in healthcare, there is a growing interest among researchers in ethnomedicinal sources for the discovery of novel therapeutic compounds. This includes the re-evaluation of formulations and therapeutic indications that have been recognised for centuries. The remedies analysed and detailed in The Guide can provide valuable insights for researchers focused on identifying biologically active therapeutic raw materials of plant origin, thus contributing to advances in modern healthcare.

Effect of konjac glucomannan-based preservation pads on quality changes in refrigerated large yellow croaker (Pseudosciaena crocea)

The purpose of this study was to evaluate the preservation effects of konjac glucomannan (KGM)/oregano essential oil (OEO) Pickering emulsion-based pads (K/OPE pads) on large yellow croaker (Pseudosciaena crocea) fillets stored at 4 °C. The K/OPE pads were fabricated using a freeze-drying technique. The homogeneous distribution of the OEO Pickering emulsions in the KGM matrix was observed using scanning electron microscopy. Fourier transform infrared spectroscopy confirmed that the OEO emulsions were encapsulated in the KGM and there was hydrogen bonding interaction between them. Compared with the KGM pads, the K/OPE pad groups demonstrated enhanced antioxidant and antimicrobial properties. When the content of OPE was increased from 20 % to 40 %, the antioxidant performance of the K/OPE pads increased from 48.09 % ± 0.03 % to 86.65 % ± 0.02 % and the inhibition range of Escherichia coli and Staphylococcus aureus increased to 13.84 ± 0.81 and 16.87 ± 1.53 mm, respectively. At the same time, K/OPE pads were more effective in inhibiting the formation of total volatile alkaline nitrogen and the production of thiobarbituric acid-reactive substances, thereby helping in reducing water loss and maintaining the muscle tissue structure of fish fillets for a longer storage time. Consequently, these K/OPE40 pads extended the shelf life of the fish fillets by an additional 4 days and delayed spoilage during refrigerated storage. The findings suggest that the K/OPE pads can effectively safeguard the quality of refrigerated large yellow croaker fillets, presenting their potential as an active packaging material in the fish preservation industry.

A new highly active and CO2-stable heterostructure cathode material for solid oxide fuel cells developed from bismuth ion-modified cation-deficient Nd0.9BaCo2O5+δ

Efficient oxygen reduction kinetics as well as excellent stability are the main goals of current electrode materials for solid oxide fuel cells (SOFCs). Here, we present the latest findings regarding the augmentation of performance in SOFC through utilization of a novel heterogeneous cathode, consisting of an excess cation-deficient double perovskite Nd0.9BaCo2O5+δ (NBC90) backbone and in situ exsolved BaCo1-yBiyO3-x nanoparticles modified by bismuth (NBC90+B). The anisotropic growth of such self-assembled nanoparticles and the formation of multiple heterointerfaces exhibit an extremely strong activation effect. The in situ formed BaCo1-yBiyO3-x nanoparticles and cation-deficient NBC90 parental perovskite significantly enhance the catalytic activity and durability of the cathode toward oxygen reduction. The structural stability and CO2 tolerance of the cathode are greatly enhanced, which is attributed to the penetration of the high acidic Bi ions in the separated phase and the synergistic effect of the two-phase interface. The results unequivocally demonstrate the exceptional stability and efficiency of the NBC90+B composite as a promising cathode candidate for SOFCs.

Effect of konjac glucomannan-based preservation pads on quality changes in refrigerated large yellow croaker (Pseudosciaena crocea)

The purpose of this study was to evaluate the preservation effects of konjac glucomannan (KGM)/oregano essential oil (OEO) Pickering emulsion-based pads (K/OPE pads) on large yellow croaker (Pseudosciaena crocea) fillets stored at 4 °C. The K/OPE pads were fabricated using a freeze-drying technique. The homogeneous distribution of the OEO Pickering emulsions in the KGM matrix was observed using scanning electron microscopy. Fourier transform infrared spectroscopy confirmed that the OEO emulsions were encapsulated in the KGM and there was hydrogen bonding interaction between them. Compared with the KGM pads, the K/OPE pad groups demonstrated enhanced antioxidant and antimicrobial properties. When the content of OPE was increased from 20 % to 40 %, the antioxidant performance of the K/OPE pads increased from 48.09 % ± 0.03 % to 86.65 % ± 0.02 % and the inhibition range of Escherichia coli and Staphylococcus aureus increased to 13.84 ± 0.81 and 16.87 ± 1.53 mm, respectively. At the same time, K/OPE pads were more effective in inhibiting the formation of total volatile alkaline nitrogen and the production of thiobarbituric acid-reactive substances, thereby helping in reducing water loss and maintaining the muscle tissue structure of fish fillets for a longer storage time. Consequently, these K/OPE40 pads extended the shelf life of the fish fillets by an additional 4 days and delayed spoilage during refrigerated storage. The findings suggest that the K/OPE pads can effectively safeguard the quality of refrigerated large yellow croaker fillets, presenting their potential as an active packaging material in the fish preservation industry.

Synergistically improving the performance of spinel cathode for efficient oxygen reduction electrocatalyst

Optimizing the performance of ceramic fuel cells requires the creation of effective and inexpensive electrocatalysts for the oxygen reduction process. Here, we detail a plan for converting the inert spinel CoAl2O4 into a highly active and superior material for low-temperature ceramic fuel cells through Fe substitution. It turns out that the iron substitution aids in surface reconstruction, increasing oxidation-reduction reaction (ORR) activity. In addition, the reduction in energy bandgap due to Fe doping enhance the Cathode ORR performance, which may be triggered by the ions' kinetics at the surface and interface. The surface layer and Fe doping considerably aid the oxidation-reduction reaction, which creates more oxygen vacancies at the active oxygen site. The prepared materials exhibit enhanced fuel cell performance of 542 mW/cm2 at a temperature of 520 °C. Remarkably, the prepared cathode exhibits a commendable performance of 200 mW/cm2 at a temperature of 420 °C.Furthermore, the CoFe1Al1O4 cell exhibits a decreased Rp (polarization resistance) value of 0.6423 ohm-cm2 at a temperature of 520 °C, demonstrating rapid ORR kinetics. The distribution relaxation time (DRT) shows that the Cathode oxidation-reduction reaction (ORR) activity increased with Fe doping. We present a promising method for improving the oxidation-reduction reaction efficiency of low-temperature ceramic fuel cells.

Innovative ceramic pigments from recycled lithium-ion battery cathodes for inkjet applications

The booming of the electric mobility together with the need of storing renewable energies have increased the demand of lithium-ion batteries which will bring about increasing amounts of electronic waste. Besides, the need for alternative sources of certain raw materials considered critical has changed the perception of determined wastes, which are no longer considered residues but sources of raw materials. In this work, the active cathode material present in end-of-life lithium-ion batteries (Ni, Co, and Mn) was used as secondary raw material, after being properly separated, in the synthesis of a cobalt iron nickel manganese chromium black spinel ((Co, Fe, Ni, Mn) (Fe,Cr)2O4). The pigment was used in the formulation of a ceramic inkjet ink which was deposited over a single-fired porous tile and porcelain tile. Texture and brightness of the ink were not affected by the use of this waste, thus presenting excellent prospects for the industrial ceramic application.

INNOVATIVE CERAMIC PIGMENTS FROM RECYCLED LITHIUM-ION BATTERY CATHODES FOR INKJET APPLICATIONS

The booming of the electric mobility together with the need of storing renewable energies have increased the demand of lithium-ion batteries which will bring about increasing amounts of electronic waste. Besides, the need for alternative sources of certain raw materials considered critical has changed the perception of determined wastes, which are no longer considered residues but sources of raw materials. In this work, the active cathode material present in end-of-life lithium-ion batteries (Ni, Co, and Mn) was used as secondary raw material, after being properly separated, in the synthesis of a cobalt iron nickel manganese chromium black spinel ((Co, Fe, Ni, Mn)(Fe,Cr)2O4). The pigment was used in the formulation of a ceramic inkjet ink which was deposited over a single-fired porous tile and porcelain tile. Texture and brightness of the ink were not affected by the use of this waste, thus presenting excellent prospects for the industrial ceramic application.

An innovative approach to design readily synthesizable polymers for all-polymer solar cells

The communalization of all-polymer solar cells depends on the cost of active layer materials. We have introduced a framework to find the easily synthesizable polymers. Breaking Retrosynthetically Interesting Chemical Substructures (BRICS) method is used to generate a large database of polymers and synthetic accessibility of generated polymers is predicted. The generated database is visualized using various methods. Energy levels of polymers are also predicted using pretrained machine learning models. Polymers are screened on the basis of predicted properties. Library of polymers are displayed using the T-distributed Stochastic Neighbor Embedding (t-SNE) visualization. Structure Activity Landscape Index (SALI) visualization is also used. A significant change is observed in synthetic accessibility score on structural changes. The histagradient boosting regressor is used to predict the energy levels of polymers that energy levels play significant role in the selection of materials for organic photovoltaic cells. Synthetic accessibility of polymers is analyzed and a significant number of polymers are easy to synthesize. Thirty polymers are selected through screening process that are potential candidates for organic photovoltaic cells.

Dynamic multicolour tuning in π-conjugated polymers towards flexible electrochromic displays

Multicolour electrochromic materials have been considered as a promising alternative to achieve dynamic full-colour tuning towards next-generation electronic display technology. However, the development of electrochromics with wide colour gamut and subtle multicolour tunability still remains challenging due to inflexible energy level structures in intrinsic active materials. Herein, the electrochromic π-conjugated polymers with rich and subtle colour tunability were designed and developed based on a fine adjustment on the energy level structures. The chromatic transition covers almost full-colour gamut, and each colour scheme has a rich variety of categories stemming from versatile hues, chromas and lightnesses. Moreover, the multicolour π-conjugated polymers also demonstrate superior overall electrochromic performance, including fast switching (∼1.0 s), high colouration efficiency (160.4 cm2 C−1@550 nm) and good reversibility (over 90 % retention after 10,000 cycles). As a proof of concept, ultrathin and flexible prototype devices are developed by utilizing the multicolour π-conjugated polymers as electrochromic active layer, exhibiting a wide colour gamut and highly saturated multicolour tunability. The design principles proposed in this work may also be applicable to diverse optoelectronic applications.

Impact of microplastic pollution on breaking waves

Anthropogenic plastic waste heavily pollutes global water systems. In particular, micron-sized plastic debris can have severe repercussions for the ocean flora and fauna. Microplastics may also affect physical processes such as wave breaking, which are critical for air–sea interaction and albedo. Nevertheless, the effects of micron-sized plastic debris on geophysical processes are widely unexplored. Herein, we investigate the effect of microplastic collected from the North Pacific and a surfactant mimicking surface active materials present in the ocean on the stability of foam generated by breaking wave experiments. We found that microplastic particles increase foam stability. In particular, an increased foam height was found in a column foaming setup, while an increased foam area was observed in a laboratory-scale breaking wave channel. We propose that microplastic particles assemble at the air–water interface of foam bubbles, form aggregates, presumably decrease the liquid drainage in the liquid film, and thus change the lifetime of the liquid film and the bubble. The effect of surfactants is generally larger due to their higher surface activity but still in a range where synergistic effects can be observed. Our results suggest that microplastic could influence oceanic processes essential for air–sea interaction, sea spray formation, and albedo.

Emergent patterns in shape-asymmetric Quincke rollers

This study investigates the Quincke rolling phenomenon of snowman-shaped colloidal particles. These chiral rollers exhibit individual and collective dynamic states that depend upon the population and driving field strength. In addition to the previously identified dynamic states, such as spinning and vortex states, we identify the standing and bounded motion of the particles. The bounded motion involves the confined orbiting of particles around the center of mass due to hydrodynamic interactions at low particle area fractions. Our findings provide valuable insights into the behavior of active systems and the fabrication of active materials, emphasizing emergent order and adaptability as key guiding principles.

Bursting and transforming MOF into n-type ZnO and p-type NiO based heterostructure for supercapacitive energy storage

Metal-organic frameworks (MOFs) have been considered as great contender and promising electrode materials for supercapacitors. However, their low capacity, aggregation, and poor porosity have necessitated the exploration of new approaches to enhance the performance of these active materials. In this study, sphere-like MOF were in-situ grown and it subsequently burst, transformed into a desired metal oxide heterostructure comprising n-type ZnO and p-type NiO (ZnO/NiO-350). The resulting optimized flower-like structure, composed of interlaced nanoflakes derived from MOFs, greatly improved the active sites, porosity, and functionality of the electrode materials. The ZnO/NiO-350 electrode exhibited superior electrochemical activities for supercapacitors, compared to the parent MOF, bare n-type, and p-type counterparts. The specific capacitance can reach to 543 ​F ​g−1 at a current density of 1 ​A ​g−1. Theoretical modeling and simulations were employed to gain insights into the atomic-scale properties of the materials. Furthermore, an assembled hybrid device using active carbon and ZnO/NiO-350 as electrodes demonstrated excellent energy density of 44 ​Wh kg−1 at a power density of 1.6 Kw kg−1. After 5000 cycles at 10 ​A ​g−1, the cycling stability remained excellent 80 % of the initial capacitance. Overall, such evaluation of unique electrode with superior properties may be useful for the next generation supercapacitor electrode.