Passivation Shell Research Articles

Cathodoluminescent and Characteristic X-Ray-Emissive Rare-Earth-Doped Core/Shell Protein Labels for Spectromicroscopic Analysis of Cell Surface Receptors.

Understanding the localization and the interactions of biomolecules at the nanoscale and in the cellular context remains challenging. Electron microscopy (EM), unlike light-based microscopy, gives access to the cellular ultrastructure yet results in grey-scale images and averts unambiguous (co-)localization of biomolecules. Multimodal nanoparticle-based protein labels for correlative cathodoluminescence electron microscopy (CCLEM) and energy-dispersive X-ray spectromicroscopy (EDX-SM) are presented. The single-particle STEM-cathodoluminescence (CL) and characteristic X-ray emissivity of sub-20 nm lanthanide-doped nanoparticles are exploited as unique spectral fingerprints for precise label localization and identification. To maximize the nanoparticle brightness, lanthanides are incorporated in a low-phonon host lattice and separated from the environment using a passivating shell. The core/shell nanoparticles are then functionalized with either folic (terbium-doped) or caffeic acid (europium-doped). Their potential for (protein-)labeling is successfully demonstrated using HeLa cells expressing different surface receptors that bind to folic or caffeic acid, respectively. Both particle populations show single-particle CL emission along with a distinctive energy-dispersive X-ray signal, with the latter enabling color-based localization of receptors within swift imaging times well below 2 min per 2 while offering high resolution with a pixel size of 2.78 nm. Taken together, these results open a route to multi-color labeling based on electronspectromicroscopy.

Oxidation-Induced Oxide Shell Rupture and Phase Separation in Eutectic Gallium-Indium Nanoparticles.

Eutectic gallium-indium (EGaIn), a room-temperature liquid metal, has garnered significant attention for its applications in soft electronics, multifunctional materials, energy engineering and drug delivery. A key factor influencing these diverse applications is the spontaneous formation of a native passivating oxide shell that not only encapsulates the liquid metal but also alters the properties from the bulk counterpart. Using environmental scanning transmission electron microscopy, we report in situ observations of the oxidation of EGaIn nanoparticles by ambient air under high-energy electron beam irradiation. Our findings demonstrate that uneven oxide shell growth, driven by inward diffusion of adsorbed O species, creates unbalanced stresses. This compels the liquid metal to deform toward regions with slower oxide growth, resulting in shell rupture and allowing the liquid metal core to flow out. This process initiates top-down self-similar replication of the core-shell liquid metal nanoparticles, causing larger particles to break down into smaller particles. Additionally, internal oxidation triggers phase separation within the liquid core, ultimately leading to the pulverization of the liquid metal into finer solid particles rich in indium. These mechanistic insights into the oxidation behavior of the liquid metal hold practical implications for leveraging this process to reconfigure EGaIn nanoparticles for various applications.

Hydration-induced plasma surface modification of aluminum nanoparticles for power generation in oxygen deficient environments

An approach to increase the energy release rate from aluminum (Al) combustion is to modify the alumina (Al2O3) passivation shell surrounding the Al fuel core. One approach uses atmospheric plasma treatment to physically reduce the Al2O3 shell thickness while simultaneously exposing the defected surface to water vapor to promote surface hydration. Combining water-vapor with an atmospheric helium dielectric barrier discharge (DBD) plasma yields a thinner Al2O3 shell with double the surface hydration compared to as-received aluminum nanoparticles (nAl). Non-equilibrium combustion studies on plasma-treated nAl particles demonstrate increased energy release rates owing to the thinned shell and reduced diffusion barrier. Adding hydration further provides more oxidizer species in molecular scale proximity to the core such that the thinned and hydrated shell increased the initial pressurization rate by 50 % compared to as-received nAl. The results introduce a method to modify the native oxide surface and a strategy to control energy release rates from metal particle combustion.

Synthesis and Optical Properties of CdSeTe/CdZnS/ZnS Core/Shell Nanorods.

Semiconductor nanorods (NRs) have great potential in optoelectronic devices for their unique linearly polarized luminescence which can break the external quantum efficiency limit of light-emitting diodes (LEDs) based on spherical quantum dots. Significant progress has been made for developing red, green, and blue light-emitting NRs. However, the synthesis of NRs emitting in the deep red region, which can be used for accurate red LED displays and promoting plant growth, is currently less explored. Here, we report the synthesis of deep red CdSeTe/CdZnS/ZnS dot-in-rod core/shell NRs via a seeded growth method, where the doping of Te in the CdSe core can extend the NR emission to the deep red region. The rod-shaped CdZnS shell is grown over CdSeTe seeds. By growing a ZnS passivation shell, the CdSeTe/CdZnS/ZnS NRs exhibit a photoluminescence emission peak at 670 nm, a full width at a half maximum of 61 nm and a photoluminescence quantum yield of 45%. The development of deep red NRs can greatly extend the applications of anisotropic nanocrystals.

Revisiting the bleeding effect in historical cobalt porcelain pigments: Mechanism, influence and technical responses

The bleeding phenomenon, a persistent and widespread issue in the application of cobalt-bearing pigment during porcelain decoration, has spurred different civilisations to develop various response strategies to alleviate this problem. In this study, we challenge the prevailing hypotheses concerning the role of composition and viscosity in determining the bleeding effect on blue-and-white wares, proposing a novel physical model framing it as a diffusion process that occurs within vitreous silicate, where the severity can be qualitatively expressed using the diffusion distance. Drawing upon the phenomenological Fick's law and microscopic diffusion mechanism, we quantitatively discuss the primary physical parameters that influence the diffusion behaviour for the first time, clarifying that the diffusion of cobalt ions is not related to the medium viscosity. Moreover, compared with the microstructural features of blue decors with and without the bleeding effect, we reveal that domestic cobalt particles are all encapsulated by anorthite crystals, acting as a passivation shell to hinder the dissolution of cobalt particles. Significantly, our reinterpretation has broader archaeological implications for the bleeding effect associated with cobalt pigment in ceramics, elucidating the historical trajectories of responsive practices and the multifaceted interplay between resource form, artistic expression and technological advancement across varying environmental and cultural contexts. Overall, these responses to the bleeding effect exemplify the complexities of technological evolution, highlighting that technology is not merely an extension of technical knowledge but also functions as a form of social construction deeply intertwined with its local context. This comprehensive understanding contributes to our understanding of historical narratives in ceramics and the diversity of human ingenuity in ancient societies, with potential implications for contemporary pigment manufacture.

Mitigating Planar Gliding in Single‐Crystal Nickel‐Rich Cathodes through Multifunctional Composite Surface Engineering

AbstractNickel‐rich layered oxides are a class of promising cathodes for high‐energy‐density lithium‐ion batteries (LIBs). However, their structural instability derived from crystallographic planar gliding and microcracking under high voltages has significantly hindered their practical applications. Herein, resurfacing engineering for single‐crystalline LiNi0.83Co0.07Mn0.1O2 (SNCM) cathode is undertaken. A passivation shell, comprising a surface fast ion conductor Li1.25Al0.25Ti1.5O4 (LATO) layer and a near‐surface confined cation hybridization region, is established through co‐infiltrating Al and Ti into SNCM, which can profoundly improve structural stability. Compelling evidences show that high‐conductivity LATO‐overcoat facilitates Li+ conduction and resists electrolyte attack. The introduction of strong Al─O bonds and resurfacing regions stabilize bulk and near‐surface lattice oxygen respectively during cycling, thus hindering the formation of oxygen vacancies and the occurrence of detrimental phase transformations, ultimately suppressing the crystallographic planar gliding and nanocracking. Subsequently, the modified SNCM drastically outperforms the baseline SNCM, exhibiting an ultrahigh 88.9% retention rate of original capacity at 1.0C after 400 cycles, and a discharge capacity of 146.8 mAh g−1 with a 92.6% capacity retention rate after 200 cycles at 5.0C within a voltage window of 2.7–4.3 V. The promising performance demonstrated by the multifunctional surface coating highlights a new way to stabilize Ni‐rich cathodes for LIBs.

Use of multi-agent system for industrial production control

This paper describes specific implementation of Asset Administration Shell technology used for an industrial distributed control system. The base of this control system is a multiagent system of digital twins which was created by AAS. This multiagent system was developed for a specific platform CP Factory (mainly based on Simatic PLC) but the implementation is y portable to each common platform. Digital twin of several types of components of typical industrial production process are described in this paper with the implementation of active and passive administration shell. The main focus is on describing the way of integrating digital twins into the production system and the necessary SW tools. Industry 4.0 language was used as a common communication protocol as well as OPC UA and MQTT.

Effect of electric impedance on the electromechanical characteristics of tunable spherical piezoelectric transducer

Spherical piezoelectric transducers are a critical component of ultrasonic vibration systems with significant applications in various practical scenarios such as underwater acoustic detection and structural health monitoring. The existing spherical piezoelectric transducers have fixed electromechanical characteristics that limit their applications in scenarios with multi-frequency or frequency variation requirements. It would therefore be intriguing, from the viewpoints of both science and technology, to break through this limit by introducing external electric load impedance. Here we propose a tunable spherical piezoelectric transducer (TSPT) capable of adjusting the electromechanical characteristics by changing the resistance, inductance, and capacitance applied to the passive piezoceramic shell. The theoretical and numerical results show that when the resistance is exerted on the inner and outer piezoceramic shells, the resonance is accompanied by large variations at low values of resistance, while it becomes almost constant at high values of resistance. When the inductance is exerted on the outer piezoceramic shell, the resonance frequency obtained by the finite element method can be changed from 72730 Hz to 42928 Hz by adjusting the inductance, indicating that the TSPT can realize a rich and selective resonance frequency region. The resonance/antiresonance frequency decreases while the effective electromechanical coupling coefficient increases, when the capacitance applied on the inner and outer piezoceramic shells increases. The experiments are conducted to verify the effectiveness of the proposed TSPT, which is in agreement with the simulated results and theoretical predictions. Our methodology will offer possibilities to extend the working frequency range of the existing piezoelectric spherical transducer for underwater acoustic detection, hydrophones, and the spherical smart aggregate for civil structural health monitoring.

Growth kinetics and substrate stability during high-temperature molecular beam epitaxy of AlN nanowires

We study the molecular beam epitaxy of AlN nanowires between 950 °C and 1215 °C, well above the usual growth temperatures, to identify optimal growth conditions. The nanowires are grown by self-assembly on TiN(111) films sputtered onto Al2O3. Above 1100 °C, the TiN film is seen to undergo grain growth and its surface exhibits {111} facets where AlN nucleation preferentially occurs. Modeling of the nanowire elongation rate measured at different temperatures shows that the Al adatom diffusion length maximizes at 1150 °C, which appears to be the optimum growth temperature. However, analysis of the nanowire luminescence shows a steep increase in the deep-level signal already above 1050 °C, associated with O incorporation from the Al2O3 substrate. Comparison with AlN nanowires grown on Si, MgO and SiC substrates suggests that heavy doping of Si and O by interdiffusion from the TiN/substrate interface increases the nanowire internal quantum efficiency, presumably due to the formation of a SiN x or AlO x passivation shell. The outdiffusion of Si and O would also cause the formation of the inversion domains observed in the nanowires. It follows that for optoelectronic and piezoelectric applications, optimal AlN nanowire ensembles should be prepared at 1150 °C on TiN/SiC substrates and will require an ex situ surface passivation.

Highly Efficient Blue Light‐Emitting Diodes Based on Perovskite Film with Vertically Graded Bandgap and Organic Grain Boundary Passivation Shells

AbstractMetal halide perovskite materials have emerged as a promising class of semiconductors for high‐performance optoelectronic applications, particularly for light‐emitting diodes (LEDs), due to their high quantum efficiency, facile color tunability, narrow emission line widths, as well as cost‐effectiveness. Despite the great successes on green and red perovskite LEDs (PeLEDs), the external quantum efficiency (EQE) of blue PeLEDs still lags far behind that of green and red counterparts. Here, wavelength tunable pure and deep blue PeLEDs with high EQE are presented, achieving 17.5% and 10.8% for emission wavelengths of 472 and 461 nm, respectively. The wavelength tenability and high EQE are attributed to the unique vertically graded bandgaps and grain boundary organic shells in the perovskite films. The results demonstrate a significant performance improvement in blue PeLEDs, provide a novel route to fabricate high‐performance pure and deep blue PeLEDs that can match the performance of the green and red PeLEDs for future lighting and display applications.

Cellular temperature probing using optically trapped single upconversion luminescence

BackgroundThe thermally coupled energy states that contribute to the upconversion luminescence of rare earth element-doped nanoparticles have been the subject of intense research due to their potential nanoscale temperature probing. However, the inherent low quantum efficiency of these particles often limits their practical applications, and currently, surface passivation and incorporation of plasmonic particles are being explored to improve the inherent quantum efficiency of the particle. However, the role of these surface passivating layers and the attached plasmonic particles in the temperature sensitivity of upconverting nanoparticles while probing the intercellular temperature has not been investigated thus far, particularly at the single nanoparticle level. ResultsThe analysis of the study on the thermal sensitivity of oleate-free UCNP, UCNP@SiO2, and UCNP@SiO2@Au particles is carried out at a single particle level in a physiologically relevant temperature range (299 K–319 K) by optically trapping the particle. The thermal relative sensitivity of the as-prepared upconversion nanoparticle (UCNP) is found to be greater than that of UCNP@SiO2 and UCNP@SiO2@Au particles in an aqueous medium. An optically trapped single luminescence particle inside the cell is used to monitor the temperature inside the cell by measuring the luminescence from the thermally coupled states. The absolute sensitivity of optically trapped particles inside the biological cell increases with temperature, with a greater impact on the bare UCNP, which exhibits higher values for thermal sensitivity than UCNP@SiO2 and UCNP@SiO2@Au. The thermal sensitivity of the trapped particle inside the biological cell at 317 K indicates the thermal sensitivity of UCNP > UCNP@SiO2@Au > UCNP@SiO2 particles. Significance and noveltyCompared to bulk sample-based temperature probing, the present study demonstrates temperature measurement at the single particle level by optically trapping the particle and further explores the role of the passivating silica shell and the incorporation of plasmonic particles on thermal sensitivity. Furthermore, thermal sensitivity measurements inside a biological cell at the single particle level are investigated and illustrated that thermal sensitivity at a single particle is sensitive to the measuring environment.

Ion Beam Milling as a Symmetry-Breaking Control in the Synthesis of Periodic Arrays of Identically Aligned Bimetallic Janus Nanocrystals

Bimetallic Janus nanostructures represent a highly functional class of nanomaterials due to important physicochemical properties stemming from the union of two chemically distinct metal segments where each maintains a partially exposed surface. Essential to their synthesis is the incorporation of a symmetry-breaking control that is able to induce the regioselective deposition of a secondary metal onto a preexisting nanostructure even though such depositions are, more often than not, in opposition to the innate tendencies of heterogeneous growth modes. Numerous symmetry-breaking controls have been forwarded but the ensuing Janus structure syntheses have not yet achieved anywhere near the same level of control over nanostructure size, shape, and composition as their core-shell and single-element counterparts. Herein, a collimated ion beam is demonstrated as a symmetry-breaking control that allows for the selective removal of a passivating oxide shell from one side of a metal nanostructure to create a configuration that is transformable into a substrate-bound Au-Ag Janus nanostructure. Two different modalities are demonstrated for achieving Janus structures where in one case the oxide dissolves in the growth solution while in the other it remains affixed to form a three-component system. The devised procedures distinguish themselves in their ability to realize complex Janus architectures arranged in periodic arrays where each structure has the same alignment relative to the underlying substrate. The work, hence, provides an avenue for forming precisely tailored Janus structures and, in a broader sense, advances the use of oxides as an effective means for directing nanometal syntheses.

Cation Exchange Synthesis of Aliovalent Doped InP QDs and Their ZnSexS1-x Shell Coating for Enhanced Fluorescence Properties.

III-V quantum dots (QDs), in particular InP QDs, have emerged as high-performance and environmentally friendly candidates to replace cadmium based QDs. InP QDs exhibit properties of direct band gap structure, low toxicity, and high mobility, which make them suitable for high-performance optoelectronic applications. However, it is still challenging to precisely regulate the components and crystal structure of InP QDs, especially in the engineered stable aliovalent doping. In this work, we developed our original reverse cation exchange strategy to achieve Cu+ doped InP (InP:Cu) QDs at lower temperature. A ZnSexS1-x shell was then homogeneously grown on the InP:Cu QDs as the passivation shell. The as-prepared InP:Cu@ZnSexS1-x core-shell QDs exhibited better fluorescence properties with a photoluminescence quantum yield (PLQY) of 56.47%. Due to the existence of multiple luminous centers in the QDs, variable temperature-dependent fluorescence characteristics have been studied. The high photoluminescence characteristics in the near-infrared region indicate their potential applications in optoelectronic devices and biological fields.

Suppressing zinc dendrite growth in aqueous battery via Zn–Al alloying with spatially confined zinc reservoirs

Rechargeable aqueous zinc-ion batteries are attractive candidates as energy storage technology, but the uncontrollable Zn dendrite formation and low stripping/plating coulombic efficiency when using bare Zn metal foil as anode have severely limit the battery reliability and energy density. Thus, to develop a more robust ZIB anode with lower extent of dendrite growth, Zn–Al alloy is proposed in this work. The passivating Al2O3 shell formed on the Al phase can provide two key functions; (1) selective electrochemical stripping of Zn due to electrochemically inert Al2O3, and (2) guiding the electrodeposition of Zn on the available Zn sites. The as-prepared Zn–Al alloy anode is able to outperform the bare Zn anode as bare Zn anode shows signs of short circuit after cycling. When paired with V6O13 cathode, the Zn–Al//V6O13 cell delivers enhanced rate performance and a nearly 95% capacity retention after 1000 cycles at 3 A g−1, with a specific capacity of 280 mA h g−1. The strategy demonstrated that Zn–Al alloy is suitable for aqueous zinc-ion batteries due to its low corrosion rate, low dendrite formation, low corrosion current, and high capacity retention.

Optimal Control of Variable-Shape Wave Energy Converters

This letter solves the optimal control problem for variable-shape wave energy converters analytically, where Pontryagin’s minimum principle is applied to get the optimal control laws. The optimal control solution for the conventional fixed-shape wave energy converters requires power take-off units with bidirectional power flow capability; this means that it can harvest energy from the waves at certain times and act as an actuator at other instants to keep the system in resonance with the ocean waves. This bidirectional capability requires designing complex and expensive power take-off units. The variable shape wave energy converters were recently introduced to reduce the need for this bidirectional power capability. The main contribution of this letter is to derive the optimal control laws for variable-shape wave energy converters for the flexible passive shell and flexible controlled shell. The optimal control that maximizes the harvested energy is found to include both bang-bang and singular arc phases.

Enhancing the Efficiency of Artillery Fire by Using Passive Shell Direction Finding During Targeting

Enhancing the Efficiency of Artillery Fire by Using Passive Shell Direction Finding During Targeting

Vitamins as Active Agents for Highly Emissive and Stable Nanostructured Halide Perovskite Inks and 3D Composites Fabricated by Additive Manufacturing

AbstractThe use of non‐toxic and low‐cost vitamins like α‐tocopherol (α‐TCP, vitamin E) to improve the photophysical properties and stability of perovskite nanocrystals (PNCs), through post‐synthetic ligand surface passivation, is demonstrated for the first time. Especially interesting is its effect on CsPbI3 the most unstable inorganic PNC. Adding α‐TCP produces that the photoluminescence quantum yield (PLQY) of freshly prepared and aged PNCs achieves values of ≈98% and 100%, respectively. After storing 2 months under ambient air and 60% relative humidity, PLQY is maintained at 85% and 67%, respectively. α‐TCP restores the PL features of aged CsPbI3 PNCs, and mediates the radiative recombination channels by reducing surface defects. In addition, the combination of α‐TCP and PNCs facilitates the chemical formulation to prepare PNCs‐acrylic polymer composites processable by additive manufacturing. This enables the development of complex shaped parts with improved luminescent features and long‐term stability for 4 months, which is not possible for non‐modified PNCs. A PLQY ≈92% is reached in the 3D printed polymer/PNC composite, the highest value obtained for a red‐emitting composite solid until now as far as it is known. The passivation shell provided by α‐TCP makes that PNCs inks do not suffer any degradation process avoiding the contact with the environment and preserve their properties after reacting with polar monomers during composite polymerization.

Enhanced removal performance of zero-valent iron towards heavy metal ions by assembling Fe-tannin coating.

Heavy metals (HMs) pose serious threats to both human and environmental health and therefore, effective and low-cost techniques to remove HMs are urgently required. Here we report a facile Fe-tannin coating method for zero-valent iron (ZVI) including nanoparticles (nZVI) and foam (Fefoam), and demonstrate that the generated Fe-tannin coating would remove the inherent passive iron oxide shell of ZVI and provide channels for the galvanic replacement reaction between ZVI and HM ions. Electrochemical characterizations demonstrate that the Fe core of the modified ZVI materials could be easily oxidized and transfer electrons to HM ions owing to the facile mass transport and charge transfer. In 40min, nZVI@Fe-TA exhibits excellent performances for Cd(II), Ni(II), Pb(II), Hg(II), Cu(II) and Cr(VI) removal, with the apparent removal rate constants of 0.083, 0.085, 0.083, 0.073, 0.092 and 0.078min-1, respectively. It is found that the surface area normalized rate constants of nZVI@Fe-TA are 4-7 times higher than that of nZVI@Fe2O3 counterpart, suggesting that the improved HM removal reactivity of nZVI@Fe-TA is derived from the surface modification. Moreover, nZVI@Fe-TA has advantages in resisting interference and in the simultaneous removal of different HM ions. Under a 30min hydraulic retention time, Fefoam@Fe-TA could remove 98% HMs in the successive process. For real electroplating wastewater, Fefoam@Fe-TA exhibits excellent performance for Cr(VI) and Ni(II) removal, producing effluent of stable quality that meets local emission regulation. This study provides a facile strategy to remove the inherent passive iron oxide shell and enhance the HM removal reactivity for ZVI materials.

Liquid metal embrittlement to boost reactivity and combustion performance of Al in composite propellants

Aluminum (Al) powder has been widely used in solid composite propellants (SCPs) due to its high energy density and appropriate combustion kinetics. However, the presence of a passivation shell (Al2O3) on the surface of Al would reduce its reactivity and heat release. Herein, a facile ‘one-step’ modification method was proposed for the fabrication of micron-sized Al substitutes in SCP, aiming to induce the involvement of Al cores in the reaction by letting the liquid metal embrittlement (LME) damage the homogeneous Al2O3 shell. Oxidation weight gain experiments in the air atmosphere were conducted to investigate the effect of liquid metal content on the breakthrough of the Al2O3 shell to improve ignition and combustion performance. Moreover, the composites with gallium-based liquid metal (Galinstan) addition of 3 wt% exhibited the largest oxidation weight gain and oxidation weight gain rates, which were approximately 6 and 8-fold higher than that of the raw-Al particles, respectively. Furthermore, the resulting Galinstan-modified aluminum-based powder (GLM-Al) was used as a metal fuel for the formulation of SCP to validate its thermal and combustion properties. According to the DSC results, the heat release of SCP-2 containing GLM-Al was 3321 J·g−1, which is 1.42 folds of that from the reference SCP-1(2341 J∙g−1). Furthermore, SCP-2 exhibited a 12 % increase in burning rate under 0.1 MPa air atmosphere and a much higher pressurization rate (5.4 MPa·s−1) than that of SCP-1 (2.6 MPa·s−1) under 1 MPa argon atmosphere. The resulting condensed combustion product (CCP) size of SCP-2 is much smaller than that of SCP-1.

Inverse kinematics strategies for physical human-robot interaction using low-impedance passive link shells

AbstractThis paper presents an investigation of the effectiveness of different inverse kinematics strategies in a context of physical human-robot interaction in which passive articulated shells are mounted on the links of a serial robot for manual guidance. The concept of passive link shells is first recalled. Then, inverse kinematics strategies that are designed to plan the trajectory of the robot according to the motion sensed at the link shells are presented and formulated. The different approaches presented all aim at interpreting the motion of the shells and provide an intuitive interaction to the human user. Damped Jacobian based methods are introduced in order to alleviate singularities. A serial 5-dof robot used in previous work is briefly introduced and is used as a test case for the proposed inverse kinematics schemes. The robot includes two link shells for interaction. Simulation results based on the different inverse kinematic strategies are then presented and compared. Finally, general observations and recommendations are discussed.