Reversible Variation Research Articles

Facile synthesis of GexSiO(1-x) alloys as a superior anode enables high-energy lithium-ion batteries

The large-scale development of low-cost silicon monoxide (SiO) anode is limited due to its low initial Coulombic efficiency (ICE) and poor cycle stability. Herein, the GexSiO(1-x) (0<x<1) composite anode has been facile synthesized by introducing germanium (Ge) atoms disrupted the structure of SiO matrix, which exhibits superior lithium storage performance. In particular, the optimized Ge0.5SiO0.5 electrode with nanoscale dispersion shows a high ICE of 80.2 % and a reversible capacity of 673.9 mAh g−1 after 100 cycles. To evaluate the effect of the Ge addition on the electrochemical properties, the lithium storage behaviors and structural evolution of the GexSiO(1-x) electrodes are investigated systematically. The in-situ electrochemical dilatometry reveals that the Ge0.5SiO0.5 electrode displays a better reversible thickness variation during cycling process. Density functional theory (DFT) calculation demonstrates that the SiGe domain can accommodate the volume expansion of Si and Ge domains. Moreover, the relationships between the electrochemical performance and morphology evolution demonstrate that the disordered structure and nanoscale distribution of Ge0.5SiO0.5 electrodes are the main reasons for improving ICE and cycle stability. This work provides a commercially available synthetic route for the design of advanced anode materials for large-scale energy storage applications.

Sol-Gel Pt-VO2 Films as Selective Chemoresistive and Optical H2 Gas Sensors.

In this work, VO2 (M1/R) thin films were exploited as H2 gas sensors. A flat film morphology, obtained by furnace annealing, was compared with a laser-induced nanostructured one. The combination of the environmentally friendly sol-gel approach with the ultrafast laser crystallization allows for significant reductions in energy consumption and related emissions during the fabrication of VO2 sensors. By decorating the sensors' surface with Pt nanoparticles (NPs), the sensor response was enhanced exploiting the hydrogen spillover effect. The Pt/VO2 sensors, tested at operating temperatures between 20 and 200 °C and for concentration of H2 from few ppm to 50000 ppm, offered a dual chemoresistive and optical sensing mode. Low operating temperatures of 150 °C were achieved, along with a detection limit as low as 2 ppm and a perfect baseline recovery. Both sensors guaranteed specific selectivity toward H2, without response to NO2 or humidity, and long-term stability over 500 h. The H2 sensing mechanism, for both the monoclinic and rutile VO2 phases, was investigated through in operando X-ray Diffraction and in situ X-ray Photoelectron Spectroscopy tests. The interaction was found to be based on the reversible formation of HxVO2 bronze, along with the reversible variations in the oxidation state of V.

Biological Cell Response to Electric Field: A Review of Equivalent Circuit Models and Future Challenges.

Biological cells, characterized by complex and dynamic structures, demand precise models for comprehensive understanding, especially when subjected to external factors such as electric fields (EF) for manipulation or treatment. This interaction is integral to technologies like pulsed electric fields (PEF), inducing reversible and irreversible structural variations. Our study explores both simplified and sophisticated equivalent circuit models for biological cells under the influence of an external EF, covering diverse cell structures from single- to double-shell configurations. The paper highlights challenges in circuit modeling, specifically addressing the incorporation of reversible or irreversible pores in the membrane during external EF interactions, emphasizing the need for further research to refine technical aspects in this field. Additionally, we review a comparative analysis of the performance and applicability of the proposed circuit models, providing insights into their strengths and limitations. This contributes to a deeper insight of the complexities associated with modeling biological cells under external EF influences, paving the way for enhanced applications in medical and technological domains in future.&#xD.

Multifunctional electrochromic yarns for variable optical and thermal regulation

In this study, tungsten oxide and polyaniline hybrid films were deposited on the surface of stainless steel yarns by electrochemical deposition, and the electrochromic yarns with double electrochromic layer structure were formed. WO3 acts as a protective layer and binder to connect PANI nanorods, thereby improving electrochemical stability and electrochromic performance. The electrochromic yarns present five color changes in the voltage range of −0.4 V-1.1 V, the optical modulation of 59.98 %, the response time of 0.75 s, the coloration efficiency of 74.89 cm2/C, good electrochemical cycling stability (100 cycles without significant degeneration) and washing durability. At the same time, stable electrochromic behavior is still maintained in the bending state. The device based electrochromic yarns also has reversible multi-color variation, fast reaction time, and long-term stability. What's more, the device can be embroidered or woven into the fabric and designed into patterns of different colors. More color combinations can be achieved by adjusting the voltage. Finally, the fabric based on multifunction electrochromic yarns are used to study the thermal shielding performance. It can effectively block thermal radiation. These results indicate that the electrochromic yarn has promising potential for high-performance optical and thermal regulation applications. This research provides a prospective strategy for constructing multifunctional electronic devices in wearable application.

New Insights in Luminescence and Quenching Mechanisms of Ag2S Nanocrystals through Temperature-Dependent Spectroscopy.

Bright near-infrared-emitting Ag2S nanocrystals (NCs) are used for in vivo temperature sensing relying on a reversible variation in intensity and photoluminescence lifetime within the physiological temperature range. Here, to gain insights into the luminescence and quenching mechanisms, we investigated the temperature-dependent luminescence of Ag2S NCs from 300 to 10 K. Interestingly, both emission and lifetime measurements reveal similar and strong thermal quenching from 200 to 300 K, indicating an intrinsic quenching process that limits the photoluminescence quantum yield at room temperature, even for perfectly passivated NCs. The low thermal quenching temperature, broadband emission, and multiexponential microsecond decay behavior suggest the optical transition involves strong lattice relaxation, which is consistent with the recombination of a Ag+-trapped hole with a delocalized conduction band electron. Our findings offer valuable insights for understanding the optical properties of Ag2S NCs and the thermal quenching mechanism underlying their temperature-sensing capabilities.

Multi-physical channels response in a novel layered perovskite: (trans-4-methylcyclohexylammonium)2[CuCl4]

With the continuous development of society, the demand for multi-physical channel responsive materials continues to increase, and it is urgent to develop multi-channel responsive materials with excellent properties. Here, in this work, we reported a novel two-dimensional (2D) organic–inorganic hybrid perovskite, (trans-4-methylcyclohexylammonium)2[CuCl4] (1), with responsive multi-physical channels. 1 experienced a structural phase transition with switchable thermochromism and dielectric response, which has great potential in the application of responsive materials. Under thermal stimulation, crystal 1 displays a reversible color variation between green and yellow. Crystal structure determination reveals that the distortion of inorganic layers plays a predominant role in the thermochromism during the phase transition process. This finding presents a compelling avenue for developing multi-physical channel responsive materials and contributes valuable insights to the exploration of two-dimensional lead-free perovskites for applications in intelligent window technology.

Regulating the Ion Transport in the Layered V2O5 Electrochromic Films with Tunable Interlayer Spacing

AbstractUnveiling the ion transport mechanism to design and explore efficient and stable ion transport pathways for high‐performance transition metal oxide (TMO)−based electrochromic materials is highly desired yet challenging. Herein, this study has demonstrated that the interlayer spacing of layered vanadium penoxide (V2O5) films can be tuned by inserting different amounts of lithium−ion (Li+) within host V2O5 material, as well as adjusting ion transport behavior and electrochromic performance. These results show that V2O5 with a small amount of ion insertion delivers a stable ion transport process and electrochromic properties. Increasing the amount of inserted Li+ will enlarge the interlayer spacing, which provides abundant active sites and efficient ion transport channels, and thus reversible and rich color variation of yellow−green−blue−olive green−orange is realized. Nevertheless, an excess of ion insertion results in the crystal structure collapse and cyclic stability degradation. These findings give a rationale for the evolution of electrochromic properties during different electrochemical reaction stages. This work provides considerable insight into the ion transport behavior within the layered V2O5 films, which gives fundamental theoretical guidance for developing and designing superior layered TMO electrochromic materials.

Mechanically Ultra-Robust Fluorescent Elastomer for Elaborating Auxetic Composite.

Fluorescent elastomers are predominantly fabricated through doping fluorescent components or conjugating chromophores into polymer networks, which often involves detrimental effects on mechanical performance and also makes large-scale production difficult. Inspired by the heteroatom-rich microphase separation structures assisted by intensive hydrogen bonds in natural organisms, an ultra-robust fluorescent polyurethane elastomer is reported, which features a remarkable fracture strength of 87.2MPa with an elongation of 1797%, exceptional toughness of 678.4MJm-3 and intrinsic cyan fluorescence at 445nm. Moreover, the reversible fluorescence variation with temperature could in situ reveal the microphase separation of the elastomer in real time. By taking advantage of mechanical properties, intrinsic fluorescence and hydrogen bonds-promoted interfacial bonding ability, this fluorescent elastomer can be utilized as an auxetic skeleton for the elaboration of an integrated auxetic composite. Compared with the auxetic skeleton alone, the integrated composite shows an improved mechanical performance while maintaining auxetic deformation in a large strain below 185%, and its auxetic process can be visually detected under ultraviolet light by the fluorescence of the auxetic skeleton. The concept of introducing hydrogen-bonded heteroatom-rich microphase separation structures into polymer networks in this work provides a promising approach to developing fluorescent elastomers with exceptional mechanical properties.

Vanadium dioxide/aluminum composites for adaptive infrared stealth

Vanadium dioxide (VO2) is assumed as a promising dynamic infrared stealth material owing to its tunable emissivity. However, the relatively high emissivity associated with VO2-based adaptive infrared stealth materials poses a constraint on their practical applications. To address this issue, this study proposed a VO2/Al composite endowed with a smart infrared stealth function. With 50 % VO2, the composite achieved a low emissivity value of 0.54 at 30 °C, while it exhibited a reversible variation to 0.43 at 100 °C, demonstrating a change up to 0.11. When the temperature of the sample remained at 100 °C, the surface temperature detected by an infrared camera was only 53.4 °C, indicating a promising infrared stealth performance. Meanwhile, the metal-insulator transition (MIT) effect and thermal insulation performance were investigated under the framework of the composition effect of composite materials. The design strategy of this metal composite material paves the way for novel approaches in designing dynamic infrared stealth materials with low emissivity.

Microporous Sulfur-Carbon Materials with Extended Sodium Storage Window.

Developing high-performance carbonaceous anode materials for sodium-ion batteries (SIBs) is still a grand quest for a more sustainable future of energy storage. Introducing sulfur within a carbon framework is one of the most promising attempts toward the development of highly efficient anode materials. Herein, a microporous sulfur-rich carbon anode obtained from a liquid sulfur-containing oligomer is introduced. The sodium storage mechanism shifts from surface-controlled to diffusion-controlled at higher synthesis temperatures. The different storage mechanisms and electrode performances are found to be independent of the bare electrode material's interplanar spacing. Therefore, these differences are attributed to an increased microporosity and a thiophene-rich chemical environment. The combination of these properties enables extending the plateau region to higher potential and achieving reversible overpotential sodium storage. Moreover, in-operando small-angle X-ray scattering (SAXS) reveals reversible electron density variations within the pore structure, in good agreement with the pore-filling sodium storage mechanism occurring in hard carbons (HCs). Eventually, the depicted framework will enable the design of high-performance anode materials for sodium-ion batteries with competitive energy density.

Mn2+/Er3+‐Codoped Cs2AgInCl6 Double Perovskites with Dual Emission and Photochromism Properties for Anti‐Counterfeiting Application

AbstractHighly transparent inorganic photochromic materials have several promising applications, especially for anti‐counterfeiting application. Enriching and enhancing the luminescent properties of perovskite by doping transition metals and rare earth elements into the host is a feasible and attractive route. Codoping of Mn2+ and Er3+ can realize novel anti‐counterfeiting properties with upconversion emission and photochromic ability within a double perovskite structure of Cs2AgInCl6.The Cs2AgInCl6: Mn2+, Er3+ single crystal can be observed in a reversible color variation from yellow to dark violet by implementing under 365, 520 nm illumination or thermal treatment. In addition, the crystal emits red and green light under the excitation of 365 nm ultraviolet and 980 nm laser, respectively. The introduction of Mn2+ endowed Cs2AgInCl6 with photochromic ability, and Mn2+ acted as a bridge for energy transfer from host excitons to Er3+, facilitating emission in the visible region. Er3+ achieve upconversion luminescence in the material through its abundant energy levels and acting synergistically with Mn2+. Herein, the Cs2AgInCl6:Mn2+, Er3+ combines various optical properties and has applications for specific anti‐counterfeiting demands.

Electroactive 4D Porous Scaffold Based on Conducting Polymer as a Responsive and Dynamic In Vitro Cell Culture Platform.

In vivo, cells reside in a 3D porous and dynamic microenvironment. It provides biochemical and biophysical cues that regulate cell behavior in physiological and pathological processes. In the context of fundamental cell biology research, tissue engineering, and cell-based drug screening systems, a challenge is to develop relevant in vitro models that could integrate the dynamic properties of the cell microenvironment. Taking advantage of the promising high internal phase emulsion templating, we here designed a polyHIPE scaffold with a wide interconnected porosity and functionalized its internal 3D surface with a thin layer of electroactive conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) to turn it into a 4D electroresponsive scaffold. The resulting scaffold was cytocompatible with fibroblasts, supported cellular infiltration, and hosted cells, which display a 3D spreading morphology. It demonstrated robust actuation in ion- and protein-rich complex culture media, and its electroresponsiveness was not altered by fibroblast colonization. Thanks to customized electrochemical stimulation setups, the electromechanical response of the polyHIPE/PEDOT scaffolds was characterized in situ under a confocal microscope and showed 10% reversible volume variations. Finally, the setups were used to monitor in real time and in situ fibroblasts cultured into the polyHIPE/PEDOT scaffold during several cycles of electromechanical stimuli. Thus, we demonstrated the proof of concept of this tunable scaffold as a tool for future 4D cell culture and mechanobiology studies.

Aluminum ion chemistry of Na4Fe3(PO4)2(P2O7) for all-climate full Na-ion battery

Na4Fe3(PO4)2(P2O7) (NFPP) is currently drawing increased attention as a sodium-ion batteries (SIBs) cathode due to the cost-effective and NASICON-type structure features. Owing to the sluggish electron and Na+ conductivities, however, its real implementation is impeded by the grievous capacity decay and inferior rate capability. Herein, multivalent cation substituted microporous Na3.9Fe2.9Al0.1(PO4)2(P2O7) (NFAPP) with wide operation-temperature is elaborately designed through regulating structure/interface coupled electron/ion transport. Greatly, the derived Na vacancy and charge rearrangement induced by trivalent Al3+ substitution lower the ions diffusion barriers, thereby endowing faster electron transport and Na+ mobility. More importantly, the existing Al—O—P bonds strengthen the local environment and alleviate the volume vibration during (de)sodiation, enabling highly reversible valence variation and structural evolution. As a result, remarkable cyclability (over 10,000 loops), ultrafast rate capability (200 C), and exceptional all-climate stability (−40–60 °C) in half/full cells are demonstrated. Given this, the rational work might provide an actionable strategy to promote the electrochemical property of NFPP, thus unveiling the great application prospect of sodium iron mixed phosphate materials.

Secure nano-communication framework using RSCV cryptographic circuit in IBM Q

In the cryptographic domain, quantum and its real-time hardware simulation make it easier to secure data during communication. Here, using quantum logic, a unique encryption technique called Reversible select, cross, and variation (RSCV) encryption and decryption, which involves swapping input data halves, is shown. In this article using IBM Q, we created a cryptographic encoder and decoder circuit design utilizing various quantum gates. Based on the encoder/decoder circuit, a simple nanocommunication framework is proposed. Further, to explore the application of the noise model, how to utilize this model to create noisy replicas of these quantum circuits to research the impacts of noise that occur for actual device output is shown. To reduce measurement mistakes, measurement calibration is performed using qiskit ignis model. Preparing all 2n basis input states and calculating the likelihood of counting in the other basis states are the key concepts. The percentage improvement we achieved is 40%, 30%, and 30%, respectively, compared to earlier ones, in RSCV encryption, decryption, and RSCV cryptographic communication architecture for fake provider noise error model. It is feasible to adjust the average outcomes of an additional interesting experiment using these calibrations.

HsdSA regulated extracellular vesicle-associated PLY to protect Streptococcus pneumoniae from macrophage killing via LAPosomes.

S. pneumoniae is a major human pathogen that undergoes a spontaneous and reversible phase variation that allows it to survive in different host environments. Interestingly, we found hsdSA , a gene that manipulated the phase variation, promoted the survival and replication of S. pneumoniae in macrophages by regulating EV production and EV-associated PLY. More importantly, here we provided the first evidence that higher EV-associated PLY (produced by D39) could form LAPosomes that were single membrane compartments containing S. pneumoniae, which are induced by integrin β1/NOX2/ROS pathway. At the same time, EV-associated PLY increased the permeability of lysosome membrane and induced an insufficient acidification to escape the host killing, and ultimately prolonged the survival of S. pneumoniae in macrophages. In contrast, lower EV-associated PLY (produced by D39ΔhsdSA ) activated ULK1 recruitment to form double-layered autophagosomes to eliminate bacteria.

Temperature controlled swelling of graphene oxide for switchable dehumidification membranes

Variation of water permeance and interlayer spacing of graphene oxide (GO) is traced with in-situ X-ray diffraction upon its heating/cooling in dry (∼1000 Pa), humid (∼100 % RH) air and liquid water. Reversible variation of GO interlayer distance ranging 8.3-7.2 Å in dry air, 11-7.5 Å in humid air and 13.9-12.4 Å in liquid water is revealed in the temperature range of 25–80 °C. Accounting for GO layer thickness of ∼6 Å it corresponds manifold alterations of slit width with temperature and water vapor pressure, resulting in over 3 orders of magnitude variation of membrane performance. A typical rise of the permeance of 300–500 % within the temperature range at constant humidity is contraposed to a miserable increase in the activation energy for H2O transport, revealing the decisive impact of slit sizes on GO performance. The effect is addressed to entropy-driven variation of water absorption heat with slit sizes in GO. Variation of interlayer spacing of ∼10 % was also exposed with thermal dissociation of GO groups and H+ migration to the interlayer space as supported by semi-empirical calculations. Reversible structural changes in GO are successfully exploited for fabrication thermally switched membranes for dehumidification with initial permeance of ∼1.1·10−6 mol m−2 Pa−1·s−1 and its variation over 50 % at supplied power of ∼500 W/m2.

Inter-Shell Sliding in Individual Few-Walled Carbon Nanotubes for Flexible Electronics.

Few-walled carbon nanotube (FWCNT) is composed of a few coaxial shells of CNTs with different diameters. The shells in one tube can slide relatively to each other under external forces, potentially leading to regulated electrical properties, which are never explored due to experimental difficulties. In this work, the electromechanical response induced by inter-shell sliding of individual CNTs is studied and revealed the linear electrical current variation for the first time. Based on centimeter-long FWCNTs grown through chemical vapor deposition, controllable and reversible inter-shell sliding is realized while simultaneously recording the electrical current. Reversible and linear current variation with inter-shell sliding is observed, which is consistent with the proposed inter-shell tunneling model. Further, a silk fibroin-assisted transfer technique is developed for long CNTs and realized the fabrication of FWCNT-based flexible devices. Tensile stress can be applied on the FWCNTs@silk film encapsulated in elastic silicone to induce inter-shell sliding and thus controls electrical current, which is demonstrated to serve as a new human-machine interface with high reliability. Besides, it is foreseen that the electromechanical behaviors induced by inter-layer sliding in 1D nanotubes may also be extended to 2D layered materials, shedding new light on the fabrication of novel electronics.

Extending phase-variation voltage zones in P2-type sodium cathodes through high-entropy doping for enhanced cycling stability and rate capability

P2-type layered sodium oxides hold great promise for grid-scale energy storage applications owing to their low-cost merit, while their detrimental structural and chemical transition lead to low reversible capacities and poor cycling stability. Herein, we leverage a high-entropy (HE) doping strategy to stabilize the P2-type Na0.667Mn0.667Ni0.167Co0.167O2 (NMNC) cathode. A novel Na0.667Mn0.667Ni0.167Co0.117Ti0.01Mg0.01Cu0.01Mo0.01Nb0.01O2 (HE-NMNC) composite, with five equal content (1 at %) of cation substitution and exhibiting a pure P63/mmc space group structure, is proposed. Interestingly, a reversible P2-type phase variation is identified for HE-NMNC at high degrees of charge, but such phase variation occurs in a wider voltage region and is much slower than that in the NMNC baseline. It is demonstrated that the HE-NMNC delivers outstanding rate capability and cycling stability under a charging cutoff voltage of 4.5 V, achieving a reversible capacity of 111 mAh/g at 5 C and retaining around 130 mAh/g after 100 cycles at 1 C. Apart from the charge compensation of main transition metals (Ni, Co, and Mn), the reversible redox of lattice oxygen also contributes to the capacity of HE-NMNC upon cycling. The proposed high-entropy doping strategy and reaction mechanism may provide new insights for developing advanced cathode materials.

Tunable IR perfect absorbers enabled by tungsten doped VO2 thin films

The temperature tunability of complex dielectric constants of vanadium dioxide (VO2) makes it a promising phase-change material for use in active, dynamic, tunable photonics applications. Specifically, the semiconductor-to-metal phase transition in VO2 enables reversible, broadband, and large complex refractive index variation and paves the way for a plethora of applications. Although the critical temperature for phase-transition is 68 °C for VO2 films, its transition temperature can be reduced to room temperature by tungsten-doping of vanadium dioxide. Such a degree of freedom in controlling the critical temperature through tungsten doping provides further tunability of the thermochromic behavior. In this work, we investigate a variety of W-doped VO2 thin films deposited by laser ablation of targets with increasing W doping content and report detailed infrared characterization together with numerical simulations. Our experimental results indicate that the perfect absorption can be achieved at different temperatures, within the VO2 insulator-to-metal phase transition process, as a function of W doping content. Tunable subwavelength layers allow perfect absorption under different temperature conditions around λ = 12 µm. We show that a high dynamic range of reflectivity can be achieved when the temperature is increased above the phase transition temperature. Furthermore, we observe perfect absorption at 11.8 µm at room temperature for a W content of 0.75%. We believe that W-doped VO2 thin films with tunable and controllable perfect absorption will open the way for a class of promising thermo-optical devices including thermos-photovoltaics, infrared filters, radiative cooling devices, and thermal emitters.

Switch of cell migration modes orchestrated by changes of three-dimensional lamellipodium structure and intracellular diffusion

Cell migration plays important roles in many biological processes, but how migrating cells orchestrate intracellular molecules and subcellular structures to regulate their speed and direction is still not clear. Here, by characterizing the intracellular diffusion and the three-dimensional lamellipodium structures of fish keratocyte cells, we observe a strong positive correlation between the intracellular diffusion and cell migration speed and, more importantly, discover a switching of cell migration modes with reversible intracellular diffusion variation and lamellipodium structure deformation. Distinct from the normal fast mode, cells migrating in the newly-found slow mode have a deformed lamellipodium with swollen-up front and thinned-down rear, reduced intracellular diffusion and compartmentalized macromolecule distribution in the lamellipodium. Furthermore, in turning cells, both lamellipodium structure and intracellular diffusion dynamics are also changed, with left-right symmetry breaking. We propose a mechanism involving the front-localized actin polymerization and increased molecular crowding in the lamellipodium to explain how cells spatiotemporally coordinate the intracellular diffusion dynamics and the lamellipodium structure in regulating their migrations.