Macroscopic Dimensions Research Articles

Material extrusion of topologically engineered architecture inspired by carbon-based interlocked petal-schwarzites

Exploiting the topologically engineered complex Schwarzite architecture has allowed the creation of innovative and distinctive structural elements possessing high specific strength. These fundamental building blocks' mechanical characteristics can be fine-tuned by reinforcing them with more robust architectures featuring high surface areas. In this work, we have fabricated six distinct Schwarzite-based structures composed of multiple interlocked layers, termed architecturally interlocked petal-schwarzites. These intricate structures have been additively manufactured into macroscopic dimensions and subjected to uniaxial compression. Experimental findings reveal a correlation between the mechanical response and the number of layers. Additionally, fully atomistic molecular dynamics compressive simulations have been carried out, yielding results that are in good agreement with the experimental observations. These simulations provide insights into the underlying mechanism of high specific strength and energy absorption exhibited by architecturally interlocked petal-schwarzites. The proposed methodology introduces a new perspective on the development of engineered additively manufactured materials with tunable and enhanced mechanical properties.

Unrestricted micromorphic continuum: Curvature constraints effects

AbstractThe properties of two‐phase materials, with the special case of foams, strongly depend on their microstructure. These structures are generally modeled with Hill homogenization methods to reduce the computational effort compared to full‐resolution simulations. For applications where the macroscopic dimensions of the structure under consideration are only a few multiples of its internal length, size effects occur, that is, the effective mechanical properties depend on the structure size. To achieve adequate homogenization, higher‐order continuum theories must then be used to account for strong gradients in mechanical quantities. The present contribution extends the classical approach with the corresponding micromorphic degrees of freedom. In contrast to previous studies in the literature, all components of the micromorphic curvature tensor are incorporated. It has shown how the individual components of the third‐order curvature tensor have to be implemented. Their effects on the structural behavior are investigated in depth.

Application of advanced biosensors in nervous system diseases

AbstractNervous system diseases are among the most common diseases globally, posing a severe threat to patients' quality of life and placing a considerable burden on families and society. With improvements in miniaturization, intelligence, and the safety of biosensors, the combination of machinery and organisms is becoming increasingly common. In neuroscience research, biosensors of different macroscopic dimensions have been uniquely utilized to harness their relevant properties. One‐dimensional (1D) biosensors can achieve in situ real‐time monitoring of neural markers at the subcellular, single‐cell, ex vivo, and in vivo levels, with reduced impacts on organisms. Two‐dimensional (2D) biosensors can monitor the chemical behavior of cells and the neural activity of living animals. They are helpful for objectively identifying the characteristics of cells in response to external stimuli and studying the neural circuits of living animals. Three‐dimensional (3D) biosensors have shown unique advantages in point‐of‐care testing, liquid biopsy, drug screening, and mechanistic research. In clinical practice, brain‐computer interfaces (BCIs) and wearable devices have become important tools for monitoring and treatment. To date, there has been widespread adoption of BCIs in clinical practice. BCIs not only exhibit good efficacy in severe neurological and mental diseases but also provide a method for early diagnosis and treatment of these diseases. Wearable sensor devices can accurately assess the symptoms of movement disorders and play an active role in rehabilitation and treatment. In this review, we summarize the application of advanced biosensors in neuroscience research and clinical practice. The challenges and prospects of biosensors as applied to nervous system diseases under interdisciplinary promotion are also discussed in depth.

Analysis of Face Milling of Hard Steel 55NiCrMoV7 by Studying Rough and Semi-Finished Machining and the Influence of Cutting Parameters on Macroscopic Chip Dimensions.

Hard milling is being increasingly used as an alternative to EDM due to its high productivity. The present paper presents the results of theoretical-experimental research on the face milling of hard steel 55NiCrMoV7. A comprehensive analysis of cutting temperatures and forces during single-tooth milling and a morphological examination of the resulting chips are conducted for roughing and semi-finishing operations. The temperature is analyzed in the chip formation area, and the detached chips and the cutting force are analyzed through their tangential, radial, and penetration components, depending on the contact angle of the cutter tooth with the workpiece. The analysis of chip morphology is carried out based on the dimensional and angular parameters of chip segmentation and their degree of segmentation. Based on the central composite design and the response surface method, it is shown that it is possible to mathematically model the dependence of the macroscopic dimensions of the detached chips on the cutting parameters. The determined process functions, the maximum chip curling diameter, and the maximum chip height allow for establishing the influence of the cutting parameters' values on the chips' macroscopic dimensions and, thus, guiding the cutting process in the desired direction.

On the timescale of electrochemical processes

There is an ongoing discussion in the literature if simulations of electrochemical reactions should be performed at constant electrode potential. In this context we examine the timescales at which electrochemical processes take place. We take molecular dynamics simulation of hydrogen desorption from graphene and gold as examples. Charge transfer processes are governed by the accompanying solvent reorganization, and their speed is determined by the solvent dynamics, whose timescale is of the order of picoseconds — the exact value depends on the details of the system. In contrast, double layer relaxation, which controls the electrode potential, requires times of the order of nanoseconds. We suggest that this difference is due to the fact, that solvent reorganization is a local phenomenon, while double layer relaxation involves the whole solvent between working and reference electrodes, which is of macroscopic dimensions. We conclude, that simulations of electrochemical reactions should not be performed at constant potential. In contrast, calculations for thermodynamic properties can be performed at constant potential or at constant charge, since the question of timescales does not arise in this case.

Local Self-Assembly of Dissipative Structures Sustained by Substrate Diffusion.

The coupling between energy-consuming molecular processes and the macroscopic dimension plays an important role in nature and in the development of active matter. Here, we study the temporal evolution of a macroscopic system upon the local activation of a dissipative self-assembly process. Injection of surfactant molecules in a substrate-containing hydrogel results in the local substrate-templated formation of assemblies, which are catalysts for the conversion of substrate into waste. We show that the system develops into a macroscopic (pseudo-)non-equilibrium steady state (NESS) characterized by the local presence of energy-dissipating assemblies and persistent substrate and waste concentration gradients. For elevated substrate concentrations, this state can be maintained for more than 4 days. The studies reveal an interdependence between the dissipative assemblies and the concentration gradients: catalytic activity by the assemblies results in sustained concentration gradients and, vice versa, continuous diffusion of substrate to the assemblies stabilizes their size. The possibility to activate dissipative processes with spatial control and create long lasting non-equilibrium steady states enables dissipative structures to be studied in the space-time domain, which is of relevance for understanding biological systems and for the development of active matter.

Local Self‐Assembly of Dissipative Structures Sustained by Substrate Diffusion

AbstractThe coupling between energy‐consuming molecular processes and the macroscopic dimension plays an important role in nature and in the development of active matter. Here, we study the temporal evolution of a macroscopic system upon the local activation of a dissipative self‐assembly process. Injection of surfactant molecules in a substrate‐containing hydrogel results in the local substrate‐templated formation of assemblies, which are catalysts for the conversion of substrate into waste. We show that the system develops into a macroscopic (pseudo‐)non‐equilibrium steady state (NESS) characterized by the local presence of energy‐dissipating assemblies and persistent substrate and waste concentration gradients. For elevated substrate concentrations, this state can be maintained for more than 4 days. The studies reveal an interdependence between the dissipative assemblies and the concentration gradients: catalytic activity by the assemblies results in sustained concentration gradients and, vice versa, continuous diffusion of substrate to the assemblies stabilizes their size. The possibility to activate dissipative processes with spatial control and create long lasting non‐equilibrium steady states enables dissipative structures to be studied in the space‐time domain, which is of relevance for understanding biological systems and for the development of active matter.

Co-Assembly of Soft and Hard Nanoparticles into Macroscopic Colloidal Composites with Tailored Mechanical Property and Processability.

Colloidal composites, translating the great potential of nanoscale building bricks into macroscopic dimensions, have emerged as an appealing candidate for new materials with applications in optics, energy storage, and biomedicines. However, it remains a key challenge to bridge the size regimes from nanoscopic colloidal particles to macroscale composites possessing mechanical robustness. Herein, a bottom-up approach is demonstrated to manufacture colloidal composites with customized macroscopic forms by virtue of the co-assembly of nanosized soft polymeric micelles and hard inorganic nanoparticles. Upon association, the hairy micellar corona can bind with the hard nanoparticles, linking individual hard constituents together in a soft-hard alternating manner to form a collective entity. This permits the integration of block copolymer micelles with controlled amounts of hard nanoparticles into macroscopic colloidal composites featuring diverse internal microstructures. The resultant composites showed tunable microscale mechanical strength in a range of 90-270MPa and macroscale mechanical strength in a range of 7-42MPa for compression and 2-24MPa for bending. Notably, the incorporation of soft polymeric micelles also imparts time- and temperature-dependent dynamic deformability and versatile capacity to the resulting composites, allowing their application in the low-temperature plastic processing for functional fused silica glass.

Thermoelectric and magneto-transport characteristics of interconnected networks of ferromagnetic nanowires and nanotubes

Macroscopic-scale nanostructures, situated at the interface of nanostructures and bulk materials, hold significant promise in the realm of thermoelectric materials. Nanostructuring presents a compelling avenue for enhancing material thermoelectric performance as well as unlocking intriguing nanoscale phenomena, including spin-dependent thermoelectric effects. This is achieved while preserving high power output capabilities and ease of measurements related to the overall macroscopic dimensions. Within this framework, the recently developed three-dimensional interconnected nanowire and nanotube networks, integrated into a flexible polymer membrane, emerge as promising candidates for macroscopic nanostructures. The flexibility of these composites also paves the way for advances in the burgeoning field of flexible thermoelectrics. In this study, we demonstrate that the three-dimensional nanowire networks made of ferromagnetic metals maintain the intrinsic bulk thermoelectric power of their bulk constituent even for a diameter reduced to approximately 23 nm. Furthermore, we showcase the pioneering magneto-thermoelectric measurements of three-dimensional interconnected nickel nanotube networks. These macroscopic materials, comprising interconnected nanotubes, enable the development of large-area devices that exhibit efficient thermoelectric performance, while their nanoscale tubular structures provide distinctive magneto-transport properties. This research represents a significant step toward harnessing the potential of macroscopic nanostructured materials in the field of thermoelectrics.

Macroscopic tumor dimension, sentinel lymph node outcome, and survival analysis among cutaneous melanoma.

Cutaneous melanoma is characterized by a high risk of metastasis to distant organs and a substantial mortality rate. For planning treatment and assessing outcomes, the Breslow micrometric measurement is critical. The tumor macroscopic dimension is not considered a prognostic parameter in cutaneous melanoma, although there are studies showing that tumor size is an independent prognostic factor for melanoma-specific survival. Therefore, this study aimed to evaluate the macroscopic dimension of melanoma and other known prognostic factors (i.e., Breslow index, mitoses, regression, and ulceration) as predictors of sentinel lymph node outcome and survival outcome. We performed a retrospective cross-sectional study of 227 melanoma lesions subjected to sentinel lymph node biopsy at two Brazilian referral centers. On univariate analysis, there was a statistically significant correlation between the largest macroscopic tumor dimension and the sentinel lymph node result (P = 0.001); however, on multivariate analysis considering all evaluated parameters, there was no significant difference between the sentinel lymph node result and the tumor macroscopic dimension (P = 0.2689). Regarding melanoma-specific survival, the macroscopic dimension showed no significant correlation (P = 0.4632) in contrast to Breslow's dimension (P < 0.0001). The Breslow thickness was the only significant factor related to both the sentinel lymph node outcome and melanoma specific survival among the evaluated variables.

Benchmarking the ragone behaviour and power performance trends of pseudocapacitive batteries

The ‘holy grail’ of energy storage is to achieve both high energy and high power densities ( ⩾100 Wh l−1 and ∼104 W l−1, respectively) as characterized in a Ragone plot. However, across the macroscopic dimensions over which energy storage systems operate, power performance is fundamentally limited by both drift and diffusion processes. In this work a macroscopic variation on the Gerischer–Hopfield formalism is applied to explore how the motion of electrical charges, moving between redox species, and screening counter-ions might be engineered in a pseudocapacitive system employing quantized capacitance (in the form of a pseudocapacitive battery) to reach this long-sought metric. Our theoretical findings show that the electron diffusion timescale between redox species generally determines power performance trends when pseudocapacitive coatings are applied monolithically. This electron-diffusion–dominated timescale, in turn, is shown to scale with the square of the coating thickness. However, when conducting pathways (or shunts) are introduced to substantially reduce the mean distance for electron diffusion the Ragone performance becomes dominated by ion drift and diffusion—even when the diffusion constants of all species are held equal. The resulting trends, for this shunting regime, show a power performance timescale that scales in a more linear fashion with increasing thickness of the redox-active region. By analyzing the Ragone performance metrics for realistic coating thicknesses between these two operational regimes, the resulting findings suggest that the diffusion constants needed to achieve the aforementioned high-performance metrics are plausibly achievable for both electronic and ionic charges in this proposed class of pseudocapacitive systems.

Self-assembled photonic cavities with atomic-scale confinement

Despite tremendous progress in research on self-assembled nanotechnological building blocks, such as macromolecules1, nanowires2 and two-dimensional materials3, synthetic self-assembly methods that bridge the nanoscopic to macroscopic dimensions remain unscalable and inferior to biological self-assembly. By contrast, planar semiconductor technology has had an immense technological impact, owing to its inherent scalability, yet it seems unable to reach the atomic dimensions enabled by self-assembly. Here, we use surface forces, including Casimir–van der Waals interactions4, to deterministically self-assemble and self-align suspended silicon nanostructures with void features well below the length scales possible with conventional lithography and etching5, despite using only conventional lithography and etching. The method is remarkably robust and the threshold for self-assembly depends monotonically on all the governing parameters across thousands of measured devices. We illustrate the potential of these concepts by fabricating nanostructures that are impossible to make with any other known method: waveguide-coupled high-Q silicon photonic cavities6,7 that confine telecom photons to 2 nm air gaps with an aspect ratio of 100, corresponding to mode volumes more than 100 times below the diffraction limit. Scanning transmission electron microscopy measurements confirm the ability to build devices with sub-nanometre dimensions. Our work constitutes the first steps towards a new generation of fabrication technology that combines the atomic dimensions enabled by self-assembly with the scalability of planar semiconductors.

Mesostructured Materials with Controllable Long-Range Orientational Ordering and Anisotropic Properties.

Inorganic-organic mesophase materials provide a wide range of tunable properties, which are often highly dependent on their nano-, micro-, or meso-scale compositions and structures. Among these are macroscopic orientational order and corresponding anisotropic material properties, the adjustability of which are difficult to achieve. This is due to the complicated transient and coupled transport, chemical reaction, and surface processes that occur during material syntheses. By understanding such processes, general criteria are established and used to prepare diverse mesostructured materials with highly aligned channels with uniform nanometer dimensions and controllable directionalities over macroscopic dimensions and thicknesses. This is achieved by using a micropatterned semipermeable poly(dimethylsiloxane) stamp to manage the rates, directions, and surfaces at which self-assembling phases nucleate and the directions that they grow. This enables mesostructured surfactant-directed silica and titania composites, including with functional guest species, and mesoporous carbons to be prepared with high degrees of hexagonal order, as well as controllable orthogonal macroscopic orientational order. The resulting materials exhibit novel anisotropic properties, as demonstrated by the example of direction-dependent photocurrent generation, and are promising for enhancing the functionality of inorganic-organic nanocomposite materials in separations, catalysis, and energy conversion applications.

Electromotive Force of Spontaneously Polarized Semiconductors

Background: Spontaneously polarized finely dispersed semiconductors can be sources of direct electric current, similar to thermoelectric converters. Their power is low due to the low electrical conductivity of the powders. Objective: Theoretical description of the electromotive force of a spontaneously polarized homogeneous semiconductor film with ionized donor centers uniformly distributed over its two surfaces and free electrons in the volume. Establishment of technical characteristics and competitive advantages of using a film as a current source converts the received energy (heat or light) into the work of an electric field. Methods: The theory of semiconductors and the laws of thermodynamics are used. Results: Analytical expressions are obtained that describe the electronic processes in a metal-semiconductor-metal three-layer film and the technical characteristics of its use as a current source. Estimates are given on the example of a silicon film with arsenic-doped surfaces. Conclusion: The universal principles for creating homogeneous solids of macroscopic dimensions are substantiated, with the efficiency of converting heat into the work of an electric field, which is significantly (by an order of magnitude) higher than the efficiency of materials used to create thermo-EMF sources. The heat absorbed by the metal-semiconductor-metal three-layer film serves as an energy source for a direct current in a closed circuit generated by this structure with an efficiency of 100%. The power of the current source 10 - 105 W/m depends on the received heat flow. A semiconductor film with a built-in electric field is an analogue of a p - n junction and does not have its drawbacks.

Revealing Deformation Mechanisms in Polymer-Grafted Thermoplastic Elastomers via In Situ Small-Angle X-ray Scattering.

The tunable properties of thermoplastic elastomers (TPEs), through polymer chemistry manipulations, enable these technologically critical materials to be employed in a broad range of applications. The need to "dial-in" the mechanical properties and responses of TPEs generally requires the design and synthesis of new macromolecules. In these designs, TPEs with nonlinear macromolecular architectures outperform the mechanical properties of their linear copolymer counterparts, but the differences in the deformation mechanism providing enhanced performance are unknown. Here, in situ small-angle X-ray scattering (SAXS) measurements during uniaxial extension reveal distinct deformation mechanisms between a commercially available linear poly(styrene)-poly(butadiene)-poly(styrene) (SBS) triblock copolymer and the grafted SBS version containing grafted poly(styrene) (PS) chains from the poly(butadiene) (PBD) midblock. The neat SBS (φSBS = 100%) sample deforms congruently with the macroscopic dimensions, with the domain spacing between spheres increasing and decreasing along and transverse to the stretch direction, respectively. At high extensions, end segment pullout from the PS-rich domains is detected, which is indicated by a disordering of SBS. Conversely, the PS-grafted SBS that is 30 vol % SBS and 70% styrene (φSBS = 30%) exhibits a lamellar morphology, and in situ SAXS measurements reveal an unexpected deformation mechanism. During deformation, there are two simultaneous processes: significant lamellar domain rearrangement to preferentially orient the lamellae planes parallel to the stretch direction and crazing. The samples whiten at high strains as expected for crazing, which corresponds with the emergence of features in the 2D SAXS pattern during stretching consistent with fibril-like structures that bridge the voids in crazes. The significant domain rearrangement in the grafted copolymers is attributed to the new junctions formed across multiple PS domains by the grafting of a single chain. The in situ SAXS measurements provide insights into the enhanced mechanical properties of grafted copolymers that arise through improved physical cross-linking that leads to nanostructure domain reorientation for self-reinforcement and craze formation where fibrils help to strengthen the polymer.

Can two-way foreign direct investment promote green innovation capability in manufacturing? The threshold role of intellectual property protection

Manufacturing is both an essential pillar of China's economy and a significant source of environmental pollution, and there is an urgent need for the manufacturing industry to use green innovation to accelerate its goal of sustainable development. From the intellectual property protection (IPP) perspective, this paper uses Chinese manufacturing and its 26 sub-sectors as a sample from 2003 to 2018, examining the impact of two-way foreign direct investment (FDI) coordinated development in manufacturing green innovation capability. The empirical results suggest that two-way FDI coordinated development enhances manufacturing green innovation, and this finding still holds after endogeneity and robustness tests. Under the influence of IPP, the relationship between two-way FDI coordinated development and manufacturing green innovation capability is nonlinear. Under the influence of macroscopic, mesoscopic, and microscopic dimensions IPP, the effect of two-way FDI coordinated development on manufacturing green innovation capability is U, Steps, and N shaped respectively. This paper's findings can provide empirical evidence for the government to formulate industrial development strategies and for manufacturing enterprises to improve their green innovation capabilities to achieve sustainable development.

Site-directed placement of three-dimensional DNA origami.

The combination of lithographic methods with two-dimensional DNA origami self-assembly has led, among others, to the development of photonic crystal cavity arrays and the exploration of sensing nanoarrays where molecular devices are patterned on the sub-micrometre scale. Here we extend this concept to the third dimension by mounting three-dimensional DNA origami onto nanopatterned substrates, followed by silicification to provide hybrid DNA-silica structures exhibiting mechanical and chemical stability and achieving feature sizes in the sub-10-nm regime. Our versatile and scalable method relying on self-assembly at ambient temperatures offers the potential to three-dimensionally position any inorganic and organic components compatible with DNA origami nanoarchitecture, demonstrated here with gold nanoparticles. This way of nanotexturing could provide a route for the low-cost production of complex and three-dimensionally patterned surfaces and integrated devices designed on the molecular level and reaching macroscopic dimensions.

Light-Driven Self-Oscillation of Thermoplasmonic Nanocolloids.

Self-oscillation-the periodic change of a system under a non-periodic stimulus-is vital for creating low-maintenance autonomous devices in soft robotics technologies. Soft composites of macroscopic dimensions are often doped with plasmonic nanoparticles to enhance energy dissipation and generate periodic response. However, while it is still unknown whether a dispersion of photonic nanocrystals may respond to light as a soft actuator, a dynamic analysis of nanocolloids self-oscillating in a liquid is also lacking. This study presents a new self-oscillator model for illuminated colloidal systems. It predicts that the surface temperature of thermoplasmonic nanoparticles and the number density of their clusters jointly oscillate at frequencies ranging from infrasonic to acoustic values. New experiments with spontaneously clustering gold nanorods, where the photothermal effect alters the interplay of light (stimulus) with the disperse system on a macroscopic scale, strongly support thetheory. These findings enlarge the current view on self-oscillation phenomena and anticipate the colloidal state of matter to be a suitable host for accommodating light-propelled machineries. In broad terms, a complex system behavior is observed, which goes from periodic solutions (Hopf-Poincaré-Andronov bifurcation) to a new dynamic attractor driven by nanoparticle interactions, linking thermoplasmonics to nonlinearity andchaos.

Is the H Atom Surrounded by A Cloud of Virtual Quanta Due to the Lamb Shift?

The Lamb shift, one of the most fundamental interactions in atomic physics, arises from the interaction of H atoms with the electromagnetic fluctuations of the quantum vacuum. The energy shift has been computed in a variety of ways. The energy shift, as Feynman, Power, and Milonni demonstrated, equals the change in the vacuum energy in the volume containing the H atoms due to the change in the index of refraction arising from the presence of the H atoms. Using this result and a group theoretical calculation of the contribution to the Lamb shift from each frequency of the vacuum fluctuations, in this paper we obtain an expression for the region of the vacuum energy for each frequency ω around the H atom due to the Lamb shift. This same field plays an essential role in the van der Waals force. We show the ground state atom is surrounded by a region of positive vacuum energy that extends well beyond the atom for low frequencies. This region can be described as a steady state cloud of vacuum fluctuations. For energies E=ℏω less than 1 eV, where ℏ is the reduced Planck constant and ω is frequency, the radius of the positive energy region is shown to be approximately 14.4/E Å. For a vacuum fluctuation of wavelength, λ, the radius is (α/2π)λ, where α is the fine-structure constant. Thus, for long wavelengths, the region has macroscopic dimensions. The energy–time uncertainty relation predicts a maximum possible radius that is larger than the radius based on the radiative shift calculations by a factor of 1/4α.

Tailoring the Swelling-Shrinkable Behavior of Hydrogels for Biomedical Applications.

Hydrogels with tailor-made swelling-shrinkable properties have aroused considerable interest in numerous biomedical domains. For example, as swelling is a key issue for blood and wound extrudates absorption, the transference of nutrients and metabolites, as well as drug diffusion and release, hydrogels with high swelling capacity have been widely applicated in full-thickness skin wound healing and tissue regeneration, and drug delivery. Nevertheless, in the fields of tissue adhesives and internal soft-tissue wound healing, and bioelectronics, non-swelling hydrogels play very important functions owing to their stable macroscopic dimension and physical performance in physiological environment. Moreover, the negative swelling behavior (i.e., shrinkage) of hydrogels can be exploited to drive noninvasive wound closure, and achieve resolution enhancement of hydrogel scaffolds. In addition, it can help push out the entrapped drugs, thus promote drug release. However, there still has not been a general review of the constructions and biomedical applications of hydrogels from the viewpoint of swelling-shrinkable properties. Therefore, this review summarizes the tactics employed so far in tailoring the swelling-shrinkable properties of hydrogels and their biomedical applications. And a relatively comprehensive understanding of the current progress and future challenge of the hydrogels with different swelling-shrinkable features is provided for potential clinical translations.