Tunable Function Research Articles

Emergence of co-tuning in inhibitory neurons as a network phenomenon mediated by randomness, correlations, and homeostatic plasticity.

Cortical excitatory neurons show clear tuning to stimulus features, but the tuning properties of inhibitory interneurons are ambiguous. While inhibitory neurons have been considered to be largely untuned, some studies show that some parvalbumin-expressing (PV) neurons do show feature selectivity and participate in co-tuned subnetworks with pyramidal neurons. In this study, we first use mean-field theory to demonstrate that a combination of homeostatic plasticity governing the synaptic dynamics of the connections from PV to excitatory neurons, heterogeneity in the excitatory postsynaptic potentials that impinge on PV neurons, and shared correlated input from layer 4 results in the functional and structural self-organization of PV subnetworks. Second, we show that structural and functional feature tuning of PV neurons emerges more clearly at the network level, i.e., that population-level measures identify functional and structural co-tuning of PV neurons that are not evident in pairwise individual-level measures. Finally, we show that such co-tuning can enhance network stability at the cost of reduced feature selectivity.

Federated learning based modulation classification for multipath channels

Deep learning (DL)-based automatic modulation classification (AMC) is a primary research field for identifying modulation types. However, traditional DL-based AMC approaches rely on hand-crafted features, which can be time-consuming and may not capture all relevant information in the signal. Additionally, they are centralized solutions that are trained on large amounts of data acquired from local clients and stored on a server, leading to weak performance in terms of correct classification probability. To address these issues, a federated learning (FL)-based AMC approach is proposed, called FL-MP-CNN-AMC, which takes into account the effects of multipath channels (reflected and scattered paths) and considers the use of a modified loss function for solving the class imbalance problem caused by these channels. In addition, hyperparameter tuning and optimization of the loss function are discussed and analyzed to improve the performance of the proposed approach. The classification performance is investigated by considering the effects of interference level, delay spread, scattered and reflected paths, phase offset, and frequency offset. The simulation results show that the proposed approach provides excellent performance in terms of correct classification probability, confusion matrix, convergence and communication overhead when compared to contemporary methods.

Bio-inspired 4D printed intelligent lattice metamaterials with tunable mechanical property

4D-printed intelligent metamaterials possess a multitude of potential applications in the engineering fields due to their novel structures and functions. In this paper, a multifunctional intelligent metamaterial inspired by arc-bearing structure in human spine and tortoise shell has been established based on 4D printing technology. The innovative metamaterial exhibits programmable shape, significantly tunable mechanical properties, reusable characteristics with good loading, energy absorbing and vibration damping ability. Theoretical models of the metamaterial are developed to describe its intelligent mechanical properties. The relationship between structural parameters and the temperature field in relation to the tunable mechanical properties and functionalities of metamaterials were displayed and analyzed by experiments, theoretical calculation and finite element analysis. The stiffness, energy absorption and vibration damping effects are regulated by varying the structural parameters and temperature field. This multifunctional and tunable metamaterial is expected to be widely applied in related fields such as aerospace engineering and intelligent robots.

Redox-Active Ruthenium-Organic Polyhedra with Tunable Surface Functionality and Porosities.

Dinuclear ruthenium paddlewheel complexes exhibit high structural stability in redox reactions. The use of these chemical motifs for the construction of Ru-based metal-organic polyhedra (RuMOPs) provides a route for redox-active porous materials. However, there are few studies on the synthesis and characterization of RuMOPs due to the difficulty in controlling the assembly process via the ligand-exchange reaction of equatorial acetates of the diruthenium tetraacetate precursors with dicarboxylic acid ligands. In this study, we synthesized three novel cuboctahedral RuMOPs based on the Ru2(II/III)-paddlewheel units with different alkyl functionalizations on the benzene-1,3-dicarboxylate moieties. We evaluated the effect of external functionalization on the molecular packing and the porous and redox properties. The electrochemical measurements revealed the multielectron transferred redox process where the electron-donating/-withdrawing nature of the functional groups allows the control of the redox behavior.

Improving performance prediction of metal-organic framework membranes for reverse osmosis via genetic algorithm optimized artificial neural networks

The pollution of water resources and the rapid development of society are leading to the decrease of available fresh water resources in the world, which intensifies the research on seawater desalination. Metal-organic frameworks (MOFs), as promising membrane materials with diversified sizes, highly porous structures, and tunable chemical functionalities, have been extensively studied for desalination in recent years. In this paper, genetic algorithm (GA) optimized back propagation (BP) artificial neural network was first constructed, which made the prediction model of MOF membranes performances more accurate. Before the GA optimization, the structure of BP model was tuned through cross-validation and hyperparameter adjustment to achieve a better prediction performance and robustness. Then the GA was introduced attaining an enhanced R2 of 0.98 and 0.99 compared to the BP model of 0.90 and 0.97 for water permeability and salt rejection, respectively, which was also superior to the random forest, support vector machine, and multiple linear regression models. In addition, the grey relational analysis was used to screen the feature variables in order to clarify the most influential factors that affect the membrane performances. It is found that the MOF size and the thickness of polyamide layer were the key influential factors. This work will provide insights for the design of high-performance MOF based membranes and further render implications for other membrane developments.

Three-dimensional magnetic nanotextures with high-order vorticity in soft magnetic wireframes

Additive nanotechnology enable curvilinear and three-dimensional (3D) magnetic architectures with tunable topology and functionalities surpassing their planar counterparts. Here, we experimentally reveal that 3D soft magnetic wireframe structures resemble compact manifolds and accommodate magnetic textures of high order vorticity determined by the Euler characteristic, χ. We demonstrate that self-standing magnetic tetrapods (homeomorphic to a sphere; χ = + 2) support six surface topological solitons, namely four vortices and two antivortices, with a total vorticity of + 2 equal to its Euler characteristic. Alternatively, wireframe structures with one loop (homeomorphic to a torus; χ = 0) possess equal number of vortices and antivortices, which is relevant for spin-wave splitters and 3D magnonics. Subsequent introduction of n holes into the wireframe geometry (homeomorphic to an n-torus; χ < 0) enables the accommodation of a virtually unlimited number of antivortices, which suggests their usefulness for non-conventional (e.g., reservoir) computation. Furthermore, complex stray-field topologies around these objects are of interest for superconducting electronics, particle trapping and biomedical applications.

Redox-active cerium-based metal–organic layers coordinated on carbon nanotubes as materials for supercapacitors

In this work, the redox-active, two-dimensional (2D), and highly dispersible metal–organic layers (MOLs) constructed from hexa-cerium(IV) clusters, CeBTB (BTB = 1,3,5-benzenetribenzoate), were directly coordinated onto the surface of carboxylic acid-functionalized multi-walled carbon nanotubes (CNTs) by utilizing a post-synthetically grafting approach. Nanocomposites with various MOL-to-CNT ratios can be synthesized. Crystallinity, porosity, morphology, electrical conductivity, and electrochemical behaviors of CeBTB and all nanocomposites as well as the chemical interaction between CeBTB and CNT in the composite are investigated. Thin films of materials with the same mass loading are then fabricated for measuring their capacitive performances in neutral aqueous solutions of Na2SO4. With the electrical conductivity provided by carbon nanotubes and the redox activity of CeBTB between Ce(IV) and Ce(III), the optimal CeBTB-CNT nanocomposite can show a better capacitive performance compared to the pristine CeBTB, pristine CNT, and the physical mixture of both of them with the same MOL-to-CNT ratio. With such a simple post-synthetically grafting approach that can precisely control the ratio between the 2D MOLs and CNTs, the findings here open opportunities for designing numerous composites composed of MOLs and nanocarbons with tunable conductivity, redox activity, and functionality, which are potential candidates for a range of applications.

Five-Band Tunable Terahertz Metamaterial Absorber Using Two Sets of Different-Sized Graphene-Based Copper-Coin-like Resonators

In this paper, a five-band metamaterial absorber with a tunable function in a terahertz band is proposed, which consists of a gold grounding layer, a polyimide dielectric layer, and a periodic patterned graphene layer. The patterned graphene layer is constructed from two sets of copper-coin-shaped structures of different sizes. The designed absorber achieves absorptions of 96.4%, 99.4%, 99.8%, 98.4%, and 99.9% at 4.62 THz, 7.29 THz, 7.70 THz, 8.19 THz, and 8.93 THz, respectively, with an average absorption intensity of 98.78%. The physical mechanism of this five-band absorber was explained by the impedance matching principle and electric field distribution. The absorption performance of the five-band absorber can be effectively tuned by changing the geometry of the patterned graphene array and the thickness of the dielectric layer. Given that the resonant frequency of the absorber varies in proportion to the Fermi level, by varying the Fermi level of the graphene hypersurface, we can achieve the continuous tuning of the absorption performance over a wide frequency range. The five-band absorber has a stable absorption performance over a wide incidence angle of 0–65°, and by combining the merits of high absorption, dynamic adjustability, and a large number of absorption peaks, the given absorber could have great potential for applications in nondestructive testing, imaging, communication, sensing, and detectors.

Wavelength continuously tunable and wavelength spacing variable comb filter based on a High-Birefringence fiber loop mirror

We demonstrated an all-fiber comb filter that can continuously tune the wavelength for four switchable wavelength spacings. The comb filter consists of a fiber loop mirror (FLM) that is inserted with three polarization maintaining fibers (PMFs) and three polarization controllers (PCs). The transmission characteristics of the comb filter was theoretically analyzed. The output characteristics of the comb filters shows a dependence of the orientation angles of the PCs. With the angles being optimally set, the comb filter with four different wavelength spacings can be achieved. The wavelength continuously tunable and wavelength spacing variable mechanisms are elaborated. The three PCs are employed to enable the tunable and switchable functions. The two PCs between the PMFs serve as a polarization rotator to align the birefringent axes of the PMFs for varying the wavelength spacing while the PC adjacent to the optical coupler can be used for wavelength tuning function. When the two quarter-waveplates (QWPs) of the PC are optimally set at π/4 and - π/4, the half-waveplate (HWP) acts as a wavelength tuning element, and when the QWPs are set at zero degrees, the HWP serves as an amplitude tuning element. The center wavelength of the comb filter could be linearly tuned with the rotation angle of the HWP, and a π/2 change in the rotation angle leads to a wavelength change in one free-spectral-range (FSR). A π/4 change in the rotation angle could bring the normalized peak transmission from its maximum at 1 to minimum at 0. The proposed tunable technique has been verified by our experimental results. We experimentally demonstrated the comb filters can switch among FSRs of 0.75 nm, 1.01 nm, 1.51 nm, and 3.1 nm with tunable functions.

MXene-Based Chemo-Sensors and Other Sensing Devices.

MXenes have received worldwide attention across various scientific and technological fields since the first report of the synthesis of Ti3C2 nanostructures in 2011. The unique characteristics of MXenes, such as superior mechanical strength and flexibility, liquid-phase processability, tunable surface functionality, high electrical conductivity, and the ability to customize their properties, have led to the widespread development and exploration of their applications in energy storage, electronics, biomedicine, catalysis, and environmental technologies. The significant growth in publications related to MXenes over the past decade highlights the extensive research interest in this material. One area that has a great potential for improvement through the integration of MXenes is sensor design. Strain sensors, temperature sensors, pressure sensors, biosensors (both optical and electrochemical), gas sensors, and environmental pollution sensors targeted at volatile organic compounds (VOCs) could all gain numerous improvements from the inclusion of MXenes. This report delves into the current research landscape, exploring the advancements in MXene-based chemo-sensor technologies and examining potential future applications across diverse sensor types.

Improving speed control characteristics of PMDC motor drives using nonlinear PI control

This paper introduces a nonlinear PI controller for improved speed regulation in permanent magnet direct current (PMDC) motor drive systems. The nonlinearity comes from the exponential (Exp) block placed in front of the classical PI controller, which uses a tunable exponential function to map the speed error nonlinearly. Such a configuration has not been studied till now, thus meriting further investigation. We consider an exponential PI (EXP-PI) controller and to attain the best performance from this controller, its parameters are optimized offline using salp swarm algorithm (SSA), which borrows its inspiration from the way of forage and navigation of salps living in deep oceans. To indicate the credibility of SSA tuned EXP-PI controller convincingly, numerous experiments on speed regulation in PMDC motor have been implemented using DSP of TMS320F28335. The results obtained are also compared to similar results in the literature. It is shown that the proposed approach performs well in practice by ensuring tight tracking of the speed reference and superb torque disturbance rejection for the closed loop control. Furthermore, superior performance is achieved by the proposed nonlinear PI controller with respect to a fixed-gain PI controller.

Neutral and Cationic Re(I) Complexes with Pnictogen-Based Coligands and Tunable Functionality: From Phosphorescence to Photoinduced CO Release.

In this work, we have explored Re(I) complexes featuring triphenylpnictogen (PnPh3, Pn = P, As, or Sb)-based coligands and bidentate (neutral or monoanionic) luminophores derived from 1,10-phenantroline (phen), as well as from 2-(3-(tert-butyl)-1H-1,2,4-triazol-5-yl)pyridine (H(N-tBu)). The effect of the increasingly heavy elements on the structural parameters, photoexcited-state properties, and electrochemical behavior as well as the hybridization defects and polarization of the Pn atoms was related to the charges of the main luminophores (i.e., phen vs N-tBu) and explored in terms of photoluminescence spectroscopy, X-ray diffractometry, and quantum-chemical methods. Therefore, an in-depth analysis of the bonding, crystal packing, excited-state energies, and lifetimes was assessed in liquid solutions, frozen glassy matrices, and crystalline phases along with a semiquantitative photoactivation study. Notably, by changing the main ligand from phen to N-tBu, an increase in radiative and radiationless deactivation rates (kr and knr, respectively) at 77 K together with a faster photoinduced CO release and fragmentation at room temperature was detected. In addition, a progressively red-shifted phosphorescence was observed with the growing atomic number of the pnictogen atom, along with a boost in kr and knr at 77 K. Down the Vth main group and upon coordination of the Pn atom to the Re(I) center, an increasingly prominent jump of s-orbital participation on the binding sxp3.00-orbitals of the Pn atoms is evidenced. Based on these findings, the ability of these complexes to act as tunable photoluminescent labels able to perform as light-driven CO-releasing molecules is envisioned.

Nanoengineering of Lanthanide‐Doped BaGdF5‐Graphene Oxide as a Tunable‐Nanocomposite Platform for Biological Applications

AbstractInorganic nanohosts doped with lanthanide ions are an indispensable tool for multimodal bioimaging and MRI applications due to their distinctive optical, magnetic, and biocompatible properties. Nanocomposites of such nanoprobes with functionalization capabilities could also enable their use in targeted therapy‐based applications. However, the influence of nanocomponents especially their proportion in a nanocomposite in modulating the physio‐chemical and biocompatibility properties of the nanocomposite is still elusive. To address this knowledge gap, we have engineered nanocomposites variants using an environmentally benign one‐step synthesis with ionic liquids. We have synthesized two nanocomposites, differing in the proportion of lanthanide‐doped ternary fluoride nanoparticles (as nanophase material with luminescent and magnetic traits) and graphene oxide (as host matrix phase with tunable functionalization potential for theranostics applications). We found that with increased GO nanomaterial, nanocomposites showed reduced crystallite size and photoluminescence properties without significantly affecting the magnetic traits. Thus, implying nanocomponents ratio has differential effect on the nanocomposite properties. To assess biocompatibility, we have employed sensitive biomarkers such as craniofacial development, cardiac rhythm, and overall survivability of zebrafish larvae. Remarkably, biocompatibility improved when the proportion of the GO was increased within the nanocomposite as compared to when the nanocomponents were assessed individually. Our results also revealed that biocompatibility of nanocomposites also depends on the synergistic interplay between the nanocomponents due to the spatial arrangement of each nanocomponent in the nanocomposites. Overall, our study offers an intriguing avenue for tuning the biocompatibility of such nanocomposites, rendering them as an application‐independent biocompatible‐platform for theranostics applications.

MXenes vs MBenes: Demystifying the materials of tomorrow’s carbon capture revolution

Two emerging materials, MXenes and MBenes, have garnered significant attention as promising candidates for CCS applications. Both materials possess unique properties that make them well-suited for CO2 adsorption, such as high surface area, porosity, and tunable chemical functionality. This perspective article presents a comparative evaluation of MXenes and MBenes for CO2 capture, leveraging advanced computational simulations and experimental data to elucidate their respective adsorption capacities, kinetic performance, and stability. The simulations reveal that both materials exhibit superior CO2 adsorption performance compared to conventional CCS materials, with MXenes demonstrating a slight edge in adsorption capacity and selectivity. Furthermore, the potential of MXenes and MBenes for CCS applications is discussed, including their layer thickness, selective affinity to CO2, advantages over conventional sorbents, regeneration, stability, and durability. The findings provide valuable insights into the structure–property relationships of MXenes and MBenes in the context of CO2 capture and shed light on the technology readiness of these materials for specific CCS applications. Finally, this perspective article aims to advance the fundamental understanding of these novel 2D materials for CCS, paving the way for future developments in sustainable CO2 capture technologies.Graphical abstractHighlightsMXenes and MBenes are two-dimensional layered materials with the potential to revolutionize carbon capture and storage (CCS). MXenes have several advantages over other CCS materials, such as greater porosity, higher CO2 adsorption capacity, and easier and less expensive production. MBenes are more stable in humid environments and have higher oxidation resistance and thermal conductivity than MXenes, making them a better choice for CCS applications where the CO2 stream is humid, hot, and/or corrosive. MXenes and MBenes have the potential to make CCS more efficient, cost-effective, and versatile.DiscussionWhy are MXenes and MBenes ideal for carbon capture applications?In terms of carbon capture efficiency, how do MXenes and MBenes stack up against other materials such as MOFs, zeolites, and activated carbons?Which are better, MXenes or MBenes, for carbon capture?Why do MXenes and MBenes have a selective affinity to CO2 compared to other gases such as N2 and O2?What is the optimal number of layers for MXenes/MBenes for carbon capture, and does interlayer spacing affect performance?What is the best surface termination for CO2 capture?What happens to the CO2 after it is absorbed onto MXene and MBene surfaces, and how can one remove CO2 that has been adsorbed?What are the major challenges, besides scalability, that need to be overcome for these materials to be practical?How durable and stable are MXenes and MBenes?

Molecular engineering toward large pore-sized covalent organic frameworks

In recent years, covalent organic frameworks (COFs) as designable crystalline porous polymers have attracted widespread attention because of their tunable structures and functionalities. In particular, the unique characteristics of COFs, such as readily controllable pore size, high surface area, editable pore surface environment, and exceptional chemical stability, provide a structural basis for loading large-sized organic, inorganic, and biological molecules for hetero-catalysis, energy storage, and other applications. In this review, we discuss state-of-the-art strategies for the structural design and synthesis, properties, and functionalities of large pore size two-dimensional and three-dimensional COFs, spotlighting recent breakthrough achievements and remarkable progress to guide further efforts in this field.

Artificial Optoelectronic Synapses Based on Light‐Controllable Ferroelectric Semiconductor Memristor

AbstractNumerous synaptic devices have been explored for the next generation of energy‐efficient computing techniques. Among them, optoelectronic synaptic devices based on semiconductor/ferroelectric heterostructures have received a lot of attention lately due to their amazing parallelism, efficiency, and fault tolerance properties. However, polarizing the ferroelectric layer or gating the dielectric layer is necessary to achieve tunable synaptic functions, which generally causes an increase in energy consumption and complex manufacturing processes. Here, a simple and efficient method is demonstrated to develop a tunable optoelectronic synaptic device based on a single ferroelectric semiconductor, BiFeO3‐BaTiO3 (BF‐BT). Multi‐essential synaptic functions including short‐term plasticity, paired‐pulse facilitation, and long‐term plasticity are all satisfactorily replicated by the memristor device. More significantly, light‐controllable synaptic behaviors are realized by altering the ferroelectric polarization state of BF‐BT. Synaptic devices’ relaxation characteristics enable simulation of the effects of positive/negative emotions on learning and forgetting processes. This study highlights the potential of the ferroelectric semiconductor memristor in constructing the efficient optoelectronic synapses for future neuromorphic electronics with the ability to learn and sense optical information.

Leveraging Tunable Nanoparticle Surface Functionalization to Alter Cellular Migration.

Gold nanoparticles (AuNPs) are a promising platform for biomedical applications including therapeutics, imaging, and drug delivery. While much of the literature surrounding the introduction of AuNPs into cellular systems focuses on uptake and cytotoxicity, less is understood about how AuNPs can indirectly affect cells via interactions with the extracellular environment. Previous work has shown that the monocytic cell line THP-1's ability to undergo chemotaxis in response to a gradient of monocyte chemoattractant protein 1 (MCP-1) was compromised by extracellular polysulfonated AuNPs, presumably by binding to MCP-1 with some preference over other proteins in the media. The hypothesis to be explored in this work is that the degree of sulfonation of the surface would therefore be correlated with the ability of AuNPs to interrupt chemotaxis. Highly sulfonated poly(styrenesulfonate)-coated AuNPs caused strong inhibition of THP-1 chemotaxis; by reducing the degree of sulfonation on the AuNP surface with copolymers [poly(styrenesulfonate-co-maleate) of different compositions], it was found that medium and low sulfonation levels caused weak to no inhibition, respectively. Small, rigid molecular sulfonate surfaces were relatively ineffective at chemotaxis inhibition. Unusually, free poly(styrenesulfonate) caused a dose-dependent reversal of THP-1 cell migration: at low concentrations, free poly(styrenesulfonate) significantly inhibited MCP-1-induced chemotaxis. However, at high concentrations, free poly(styrenesulfonate) acted as a chemorepellent, causing a reversal in the cell migration direction.

Optical nanoimaging of laser-switched phase-change plasmonic infrared antennas.

We investigate the plasmonic properties of laser-printed chalcogenide phase-change material In3SeTb2 (IST) antennas through near-field nanoimaging. Antennas of varying lengths were fabricated by laser switching an amorphous IST film into its crystalline metallic state. Near-field imaging elucidates the pronounced field confinement and enhancement at the antenna extremities along with the emergence of different ordered plasmonic modes with increasing length. Compared to gold antennas, the PCM antennas exhibit slightly lower but still substantial near-field enhancement with greater compactness. The interplay between antenna length, illumination angle, and excitation frequency enables versatile control over the resonant near-field distribution. Our work provides deeper understanding and tunable functionalities of laser-printed PCM nanoantennas for potential applications in compact, dynamically reconfigurable nanophotonic devices.

Computational screening and functional tuning of chemically stable metal organic frameworks for I2/CH3I capture in humid environments

High chemical stability is of vital significance in rendering metal organic frameworks (MOFs) as promising adsorbents for capturing leaked radioactive nuclides, under real nuclear industrial conditions with high humidity. In this work, grand canonical Monte Carlo (GCMC) and density functional theory (DFT) methods have been employed to systematically evaluate I2/CH3I capture performances of 21 experimentally confirmed chemically stable MOFs in humid environments. Favorable structural factors and the influence of hydrophilicity for iodine capture were unveiled. Subsequently, the top-performing MIL-53-Al with flexible tunability was functionalized with different functional groups to achieve the better adsorption performance. It has been revealed that the adsorption affinity and pore volume were two major factors altered by the functionalization of polar functional groups, which collectively influenced the iodine adsorption properties. In general, this work has screened the chemically stable high-performance MOF iodine adsorbents and provided comprehensive insights into the key factors affecting I2/CH3I uptake and separation in humid environments.

Encapsulation of Inorganic Nanoparticles by Anionic Emulsion Polymerization of Diethyl Methylene Malonate for Developing Hybrid Microparticles with Tailorable Composition

Colloidal particle self-assembly into higher-ordered structures has been of great interest due to the promise of creating metamaterials with novel macroscopic properties. The physicochemical properties of these metamaterials can be tailored to achieve composites with tunable functionalities, either by controlling the assembly morphology and/or chemistry of the colloidal building blocks. This work describes a strategy of developing microparticles with a hybrid configuration that have an inorganic and an organic part. The inorganic part comprises functional nanoparticles, which are embedded within an organic polymer particle composed of diethyl methylene malonate polymer [p(DEMM)] prepared using anionic emulsion polymerization. DEMM polymerization is initiated entirely by the presence of hydroxyl anions and the resulting particle diameter can be tuned between 300 nm and 1 micrometer by reaction pH. Inorganic nanoparticles with varying chemistry (TiO2, CdTe, ZnO) can be loaded into the p(DEMM) particle with a controlled weight fraction, as confirmed by thermogravimetric analysis. The colloidal stability of the composite microparticles is seen to be dependent on the ligand coating attached to the inorganic constituent. These results provide a synthetic groundwork for creating hybrid, stimuli-responsive microparticles.