Multifunctional Structures Research Articles

Multifunctional carbon/epoxy composites with power transmission capabilities

This study evaluates the power transmission of multifunctional composites with embedded conductors. The electrical conductors were constructed by braiding copper strands with Para-aramid fibers into a tape configuration, then placing these tapes within carbon/epoxy prepregs to create a multifunctional structure. Experiments were performed on these multifunctional composites under tensile loading conditions. During experimentation, the conductive tapes were incorporated within an electrical bridge to record their resistance change as a function of mechanical strain. The Digital Image Correlation (DIC) technique was used to obtain in-plane displacements and strains as a function of time. In addition, low-speed flight condition experiments with an airfoil shape composite system were carried out in a wind tunnel to study the temperature performance of these structures while under high currents. Computational models were then created to expand the experimental efforts and evaluate the system’s multiscale performance. Experimental results show that the mechanical load on the conductive tape is mainly carried by the Para-aramid yarns, leading to a relatively consistent electrical performance and airflow over the wind foil providing efficient power transmission. Lastly, the computational models showed consistency in the electrical/mechanical results and established a framework for analyzing multi-functional structures (MFS).

Editorial for Special Issue “Multifunctional Nanomaterials and Hybrid Structures for Sensors, Actuators and Smart Technologies”

Advanced materials related to sensing, actuation, catalysis, and other functionalities for interactive devices depend on surface interactions and quantum effects in solids [...].

Complete functional analysis of type IV pilus components of a reemergent plant pathogen reveals neofunctionalization of paralog genes.

Type IV pilus (TFP) is a multifunctional bacterial structure involved in twitching motility, adhesion, biofilm formation, as well as natural competence. Here, by site-directed mutagenesis and functional analysis, we determined the phenotype conferred by each of the 38 genes known to be required for TFP biosynthesis and regulation in the reemergent plant pathogenic fastidious prokaryote Xylella fastidiosa. This pathogen infects > 650 plant species and causes devastating diseases worldwide in olives, grapes, blueberries, and almonds, among others. This xylem-limited, insect-transmitted pathogen lives constantly under flow conditions and therefore is highly dependent on TFP for host colonization. In addition, TFP-mediated natural transformation is a process that impacts genomic diversity and environmental fitness. Phenotypic characterization of the mutants showed that ten genes were essential for both movement and natural competence. Interestingly, seven sets of paralogs exist, and mutations showed opposing phenotypes, indicating evolutionary neofunctionalization of subunits within TFP. The minor pilin FimT3 was the only protein exclusively required for natural competence. By combining approaches of molecular microbiology, structural biology, and biochemistry, we determined that the minor pilin FimT3 (but not the other two FimT paralogs) is the DNA receptor in TFP of X. fastidiosa and constitutes an example of neofunctionalization. FimT3 is conserved among X. fastidiosa strains and binds DNA non-specifically via an electropositive surface identified by homolog modeling. This protein surface includes two arginine residues that were exchanged with alanine and shown to be involved in DNA binding. Among plant pathogens, fimT3 was found in ~ 10% of the available genomes of the plant associated Xanthomonadaceae family, which are yet to be assessed for natural competence (besides X. fastidiosa). Overall, we highlight here the complex regulation of TFP in X. fastidiosa, providing a blueprint to understand TFP in other bacteria living under flow conditions.

Schiff base modified starch: A promising biosupport for palladium in Suzuki cross-coupling reactions

Starch can be used in diverse fields because it is a readily available, non-toxic polysaccharide with adaptable functionality and biodegradability. In this study, taking the aforementioned characteristics into consideration, we designed a modified starch (Starch-SB), which serves as supporting material for palladium stabilization. This new air and moisture-stable robust palladium composite [Starch-SB-Pd(II)] was characterized by FT-IR, XRD, TGA, XPS, SEM, EDX, TEM, CP/MAS 13C NMR, and ICP-MS analytical techniques. The catalytic studies exhibit high activity (up to 99 %) and stability in Suzuki cross-coupling reactions for this starch supported catalytic system under mild conditions (lower reaction temperature and green solvents) because of the cooperative interactions of multifunctional capturing sites on starch (Schiff base, hydroxy and amine groups) with palladium species. The experiments on reusability demonstrate that Starch-SB-Pd(II), which was prepared from functionalized starch, could be readily recycled several cycles through centrifugation. Moreover, we proposed a possibly multifunctional complex structure. This work presents an appealing and intriguing pathway for the utilization of polysaccharide as crucial support in green chemical transformations.

Influence of Perfluorooctanoic Acid on Structural, Morphological, and Optical Properties of Hybrid Silica Coatings on Glass Substrates

In recent years, various coatings based on fluorinated materials, used in a commercial application, have been created through many preparation routes. However, the techniques utilized to realize these coatings required either expensive and complex equipment, imply multiple manufacturing steps, or are time- or cost-consuming. In this paper, the major target was to develop fluorinated hybrid coatings presenting sustainable hydrophobicity and good transparency simultaneously. The sol–gel method was proposed to obtain these fluorinated hybrid coatings because it does not require expensive equipment, or the existence of stabilizing agents that reduce the storage period, it consumes less energy, and it is easy to implement. The influence of perfluorooctanoic acid, utilized in the sol–gel processing of hybrid silica materials, on the structural, morphological, and optical properties of coatings deposited on glass substrates, was evaluated. Different silane precursors (tetraethyl orthosilicate (TEOS), triethoxymethylsilane (MTES), and trimethoxyhexadecylsilane (HDTMES)) were utilized to synthesize hybrid silica materials. The properties of the obtained materials were characterized by FTIR, UV–Vis, TEM, TGA, AFM, Ellipsometry, and Contact Angle analyses. FTIR spectroscopy shows the formation of a silica network tailored with organofunctional and fluoroalkyl groups. The fluorinated silica coatings presented smooth surfaces and good transparency, with a transmittance of ~90% in the visible range. It was found that the fluorinated silica materials improved the coating’s hydrophobicity (~110° in contact angle with water). These fluorinated silica materials can create multifunctional structures with antireflective and hydrophobic coatings for possible optical devices.

Fabrication of mesoporous silica nanoparticles for targeted delivery of sunitinib to ovarian cancer cells.

Mesoporous silica nanoparticles (MSNPs) are considered innovative multifunctional structures for targeted drug delivery owing to their outstanding physicochemical characteristics. MSNPs were fabricated using the sol-gel method, and polyethylene glycol-600 (PEG600) was used for MSNPs modification. Subsequently, sunitinib (SUN) was loaded into the MSNPs, MSNP-PEG and MSNP-PEG/SUN were grafted with mucin 16 (MUC16) aptamers. The nanosystems (NSs) were characterized using FT-IR, TEM, SEM, DLS, XRD, BJH, and BET. Furthermore, the biological impacts of MSNPs were evaluated on the ovarian cancer cells by MTT assay and flow cytometry analysis. The results revealed that the MSNPs have a spherical shape with an average dimension, pore size, and surface area of 56.10 nm, 2.488 nm, and 148.08 m2g-1, respectively. The cell viability results showed higher toxicity of targeted MSNPs in MUC16 overexpressing OVCAR-3 cells as compared to the SK-OV-3 cells; that was further confirmed by the cellular uptake results. The cell cycle analysis exhibited that the induction of sub-G1 phase arrest mostly occurred in MSNP-PEG/SUN-MUC16 treated OVCAR-3 cells and MSNP-PEG/SUN treated SK-OV-3 cells. DAPI staining showed apoptosis induction upon exposure to targeted MSNP in MUC16 positive OVCAR-3 cells. According to our results, the engineered NSs could be considered an effective multifunctional targeted drug delivery platform for the mucin 16 overexpressing cells.

Bird-inspired robotics principles as a framework for developing smart aerospace materials

Birds are notable for their ability to seamlessly transition between different locomotory functions by dynamically leveraging their shape-shifting morphology. In contrast, the performance of aerial vehicles is constrained to a narrow flight envelope. To understand which functional morphological principles enable birds to successfully adapt to complex environments on the wing, engineers have started to develop biomimetic models of bird morphing flight, perching, aerial grasping and dynamic pursuit. These studies show how avian morphological capabilities are enabled by the biomaterial properties that make up their multifunctional biomechanical structures. The hierarchical structural design includes concepts like lightweight skeletons actuated by distributed muscles that shapeshift the body, informed by embedded sensing, combined with a soft streamlined external surface composed of thousands of overlapping feathers. In aerospace engineering, these functions are best replicated by smart materials, including composites, that incorporate sensing, actuation, communication, and computation. Here we provide a review of recently developed biohybrid, biomimetic, and bioinspired robot structural design principles. To inspire integrative smart material design, we first synthesize the new principles into an aerial robot concept to translate it into its aircraft equivalent. Promising aerospace applications include multifunctional morphing wing structures composed out of smart composites with embedded sensing, artificial muscles for robotic actuation, and fast actuating compliant structures with integrated sensors. The potential benefits of developing and mass-manufacturing these materials for future aerial robots and aircraft include improving flight performance, mission scope, and environmental resilience.

3D-Printed Photocurable Resin with Synergistic Hydrogen Bonding Based on Deep Eutectic Solvent

Vat polymerization, one of the 3D printing technologies, has been widely applied owing to its advantageous properties, such as high accuracy and surface quality. However, the applicability of this technology is limited to end-use product manufacturing, requiring advancements due to a gradual increase in the performance requirements and functional demands of the products. In this study, deep eutectic solvent-based photocurable resins (PCRs) with synergistic hydrogen bonding are synthesized using a facile and ecofriendly procedure to tune monomer proportions. The as-prepared PCRs, with ultralow viscosity and ultrahigh curing rate, are compatible with commercial liquid-crystal display printers. The 3D-printed parts with high optical transparency, stiffness, and thermal resistance exhibit humidity-dependent electrical conductivity and mechanical properties. In addition, the 3D-printed objects demonstrate self-healing features due to the synergistic effect of high-density hydrogen bonding in the microphase-separated polymer matrix. Moreover, different categories of structural assembly, from 2D to 3D and small to large, are demonstrated, and their solubility ensued in recycling and remolding. The synthesized PCRs are suitable for fabricating sacrificial molds, enabling the on-demand fabrication of precise multifunctional structures with various materials, which are otherwise incompatible with UV-based 3D printing, facilitating 3D printing by overcoming its material-selection limitations.

Self-organized microgratings in LiNbO3 fabricated by a slit-shaped femtosecond laser for optical attenuation

Preparing multifunctional 3D microstructures in transparent materials, such as phase plates, light attenuators, and metasurfaces, is critical in science and technology. Here, the self-organized micro-gratings were created inside the z-cut LiNbO3 using slit-shaped femtosecond laser direct writing. The effects of the processing parameters and slit widths on the micro-grating’s formation are investigated. The Raman mapping, energy dispersive spectroscopy, and the micro polariscope are adopted to understand the general mechanism of periodic gratings’ generation. An optical attenuator with a spacing of 15 μm was fabricated to demonstrate the potential of micro-grating. The attenuator showed the max attenuation (about 45 %) at 633 nm, indicating the potential application of micro-gratings in optical information processing. The micro-gratings provide a pathway for expanding the applications of LiNbO3 and fabricating multifunctional photonic structures.

Constructions of Fe3O4/HAp/Au nanohybrids with multifunctional structure for efficient photocatalysis and environmental remediation of organic dyes

The controlled synthesis of nanohybrids with magnetic metal oxides (Fe3O4), noble metals Au, and hydroxyapatite (HAp) have received considerable attention for applications in photocatalysis. Green and multifunctional Fe3O4/HAp/Au composite nanoparticles (NPs) was synthesized by facile method in the paper. The Fe3O4/HAp/Au was characterized by transmission electron microscopy(TEM), X-ray diffraction (XRD), UV, and the magnetic properties was measured. The nanohybrids (Fe3O4/HAp/Au) with biocompatibility and magnetism for photocatalytic degradation of organic dyes was developed. The improvement performance of the Fe3O4/HAp/Au in photocatalysis was evaluated by degradation of organic dye (methylene blue, MB) under visible light irradiation. The results showed that the hybrid Fe3O4/HAp/Au NPs displayed high photocatalytic activity. Also the possible mechanism was speculated. It proposed novel NPs and methodology to design and fabrication of multifunctional NPs with high quality for application in photocatalytic degradation. Furthermore, it is expected that the safe, green and multifunctional composite NPs will provide an interesting platform not only for photocatalysis, but also for developing molecular imaging probe and drug delivery with target, as well as Raman detection.

Computational design for 4D printing of topology optimized multi-material active composites

Recent efforts on design for four-dimensional (4D) printing have considered the spatial arrangement of smart materials and energy stimuli. The development of multifunctional structures and their desired mechanical/actuation performances require tackling 4D printing from a multi-material design perspective. With the materials distributions there is an opportunity to increase the spectrum of design concepts with computational approaches. The main goal being to achieve the “best” distribution of material properties in a voxelized structure, a computational framework that consists of a finite element analysis-based evolutionary algorithm is presented. It fuses the advantages of optimizing both the materials distribution and material layout within a design space via topology optimization to solve the inverse design problem of finding an optimal design to achieve a target shape change by integrating void voxels. The results demonstrate the efficacy of the proposed method in providing a highly capable tool for the design of 4D-printed active composites.

Influence pandemic COVID-19 on the socio-economic efficiency of urban transport systems

The COVID-19 pandemic has fundamentally changed the way people live, think and behave, especially in cities. The pandemic, without exaggeration, has affected all spheres of economic and social life, including affecting the functioning of urban transport systems, which are a multifunctional structure that ensures the mobility of the population. Taking into account the changes that have taken place during the COVID-19 pandemic, which had a significant impact on the functioning of urban transport systems, they face new challenges, including in the sphere of ensuring environmental safety and developing new types of mobility. Special attention in this paper is paid to such issues as studying the impact of a new coronavirus infection on the behavior of citizens of world megacities based on the analysis of international experience, determining the impact of a pandemic on the objective indicators of urban transport systems. Taking into account the identified patterns, the main short-term and long-term trends that have developed under the influence of COVID-19 are identified, a comparative description of the measures taken by the city authorities to control the virus is presented, and their possible consequences are analyzed. Examples of successful projects and activities implemented by city administrations in response to the pandemic are given to ensure the long-term sustainability of the development of transport systems.

Filter-Free Photonic Microwave I/Q Modulator for Reconfigurable Frequency Mixing

We report a simple and novel scheme to achieve the reconfigurable frequency mixing based on a filter-free photonic microwave in-phase/quadrature (I/Q) modulator. With proper photodetection configuration, four microwave frequency mixing functions are expediently reconfigured in our system: single-ended mixing, balanced mixing, I/Q mixing and image-reject mixing. The employed crucial optical modulator is a dual-polarization dual-parallel Mach–Zehnder modulator (DPol-DPMZM) driven by in-phase and quadrature intermediate frequency (IF) and local oscillator (LO) signals. The generation and switching of frequency down- and up-conversion and different mixing functions depend on the main direct current (DC) biases of the two sub-DPMZMs, instead of using additional optical hybrid, wavelength division multiplexer (WDM) or two pairs of cascaded polarization controller (PC) and polarization beam splitter (PBS) in previous reports. Our demonstrated experiment shows that the reconfigurable frequency mixer has high mixing spur suppression, frequency tunability, and image rejection ratio (IRR) of over 35 dB. The proposed simple and multifunctional structure may bring a broad potential application in radar and communication systems.

A multifunctional stealthy material for wireless sensing and active camouflage driven by configurable polarization

• A multifunctional design with energy absorption, sensing and camouflage functions • Dipole configurations is achieved by the introduction of cobalt ions • The reconfigured dipole relaxation promotes the splitting of absorption bands The dipole species transformation and polarization relaxation configuration are achieved by changing the cobalt ion stoichiometry, which precisely tailors the electromagnetic attenuation performance of bismuth iron cobalt oxide. When the stoichiometric ratio of Fe:Co is 19:1, the optimal reflection loss reaches -60 dB. The high electromagnetic attenuation performance significantly improve the linear sensitivity of the strain response and active customized stealth capability of the designed multifunctional capacitor-like structure. Therefore, the wireless multifunctional design integrates energy attenuaten of electromagnetic wave with the wireless sensing and active camouflage functions for the first time. The work provides an important step for the realization of electromagnetical multifunctional applications including electromagnetic protection and electromagnetic sensing in artificial beings, medical health and even space travel.

A vanadium dioxide-assisted switchable multifunctional metamaterial structure

The predecessor of China Optics was China Optics and Applied Optics Digest, which was founded in 1985. At that time, it was the only retrieval journal in the field of optics in China. At the end of 2008, China Optics and Applied Optics Digest was renamed

Optimization of amino acid-based poly(ester urea urethane) nanoparticles for the systemic delivery of gambogic acid for treating triple negative breast cancer.

Amino acid-based poly(ester urea urethane) (AA-PEUU) is developed from amino acid-based ester urea building blocks interconnected with urethane blocks functionalized with poly(ethylene glycol) (PEG). Each functional block consists of structural design features that could impact the properties and performances of AA-PEUU as a nanocarrier for the systemic delivery of gambogic acid (GA). The multifunctional AA-PEUU structure provides broad tunability to enable the optimization of nanocarriers. The study investigates the structure-property relationship by fine-tuning the structure of AA-PEUU, including the amino acid type, hydrocarbons, the ratio of functional building blocks, and PEGylation, to identify the nanoparticle candidate with optimized delivery performances. Compared to free GA, the optimized PEUU nanocarrier improves the intratumoral distribution of GA by more than 9-fold, which significantly enhances the bioavailability and persistence of GA after intravenous administration. In an MDA-MB-231 xenograft mouse model, GA delivered by the optimized AA-PEUU nanocarrier exhibits significant tumor inhibition, apoptosis induction, and the anti-angiogenesis effect. The study demonstrates the potency of engineering AA-PEUU nanocarriers with tailor-designed structures and versatile tunability for the systemic delivery of therapeutics in the treatment of triple negative breast tumor.

Multifunctional flexible ferroelectric thick-film structures with energy storage, piezoelectric and electrocaloric performance

Flexible ferroelectric PMN–35PT thick film structures with energy storage, piezoelectric and electrocaloric performance were prepared by the room-temperature aerosol deposition method.

Multifunctional SEI-like structure coating stabilizing Zn anodes at a large current and capacity

The SEI-like structure coating can combine the advantages of each component and give sufficient mechanical stability to the coating. The establishment of fast Zn2+ migrating pathway supports the cycling of the anode at large current and capacity.

Preparation of multi-functional type coordination compounds: spanning the quantitative restriction of oxidizing groups

Cu(HAMPZCA)2(ClO4)4·2H2O (ECCs-1) has multi-functional structure of ionic salt and coordination compounds. And it also has the good advantages of decomposition rate, oxygen balance, mechanical stimulation and explosion performance.

Ballistic performance of ultralight multifunctional cellular sandwich plates with UHMWPE fiber metal laminate skins

While an ultralight sandwich construction with cellular core can be tailored to exhibit superior load-bearing capability and blast resistance, its ballistic performance is typically inferior to its equivalent monolithic counterpart. To improve the projectile penetration resistance while maintaining the capability of load bearing and blast mitigation, this work proposed a multifunctional sandwich plate with ultra-high molecular weight polyethylene (UHMWPE) fiber metal laminate (FML) skins and aluminum honeycomb core. A combined experimental and numerical approach was employed to quantify the ballistic performance, assess the penetration process, and reveal the underlying mechanisms of the novel sandwich construction. In addition to ballistic resistance, its performance under three-point bending as well as impulsive shock loading was also assessed for multifunctional applications. Relative to all-metallic honeycomb sandwich plate having identical areal density, incorporating UHMWPE composite layers into the skin improved significantly the penetration resistance: the failure mode of the laminate skin was changed from local shear-plugging to global dishing and cracking, enabling enhanced energy absorption of the thin metallic (titanium) layers. Moreover, the use of UHMWPE FML skin for sandwich construction led to not only significantly enhanced bending capacity but also reduced maximum deflection under impulsive shock loading. Hence, the proposed cellular sandwich plate with UHMWPE FML skins can be designed as ultralight multifunctional structure with simultaneous load-bearing and blast/ballistic resistant capabilities.