Small Dimensions Research Articles

Nanocompression of 20 nm Silver Nanoparticles: In situ Aberration-Corrected TEM and Atomistic Simulations.

Single-crystalline nanoparticles play an increasingly important role in a wide variety of fields including pharmaceuticals, advanced materials, catalysts for fuel cells, energy materials, as well as environmental detection and monitoring. Yet, the deformation mechanisms of very small nanoparticles are still poorly understood, in particular the role played by single dislocations and their interaction with surfaces. In this work, silver nanoparticles with particularly small dimensions (≈20 nanometers in diameter) are compressed in situ in an aberration-corrected transmission electron microscopy (TEM) and molecular dynamics (MD) simulations. During compression, the emergence of both dislocations and nanotwins are observed. However, these defects prove to be unstable and disappear upon removal of the indenter. Atomistic simulations confirm the role played by image stresses associated with the nearby surfaces and the reduction in dislocation line length as it approaches the free surface, thereby supporting the experimental observations. These results provide justification for the frequent observation of the absence of dislocations in nanoparticles of a few nanometers in size during in situ experiments, even after significant deformation. This phenomenon contributes to the self-healing of samples through dislocation ejection toward the surfaces.

Representation of convex geometries of convex dimension 3 by spheres

AbstractA convex geometry is a closure system satisfying the anti-exchange property. This paper, following the work of Adaricheva and Bolat [1] and the Polymath REU (2020), continues to investigate representations of convex geometries with small convex dimension by convex shapes on the plane and in spaces of higher dimension. In particular, we answer in the negative the question raised by Polymath REU (2020): whether every convex geometry of convex dimension 3 is representable by circles on the plane. We show there are geometries of convex dimension 3 that cannot be represented by spheres in any $$\mathbb{R}^k$$ R k , and this connects to posets not representable by spheres from the paper of Felsner, Fishburn and Trotter [44]. On the positive side, we use the result of Kincses [55] to show that every finite poset is an ellipsoid order.

How to Combine SHJ Cell-Edge Passivation and Module Reliability?

The use of cut-cells in most of the current modules is now the norm to maximise the final product performances. But the integration of such new cell configurations also comes with new challenges, especially if small cell size dimensions such as shingle are considered. Indeed, specific edge passivation processes are often used to recover for the cut-cell losses. Alumina Oxide or Polymer deposition are the most studied approaches, with in general promising benefits proven at cell level. However, only few communications after module integration are available, in particular about the impact of these additional layers on final module reliability. We show for example that it is crucial to avoid direct deposition of AlOX over the cell metal pattern in the future interconnection area, as TC (Thermal Cycling) resilience of such modules is clearly degraded. Proper edge localization of the AlOX layer is needed to recover the initial reliability behaviour. To preserve the interconnection quality, three different approaches are investigated: (1) edge localisation of the layer by wafer stacking during deposition (2) introduction of adapted copper plating solutions allowing metal growth through the passivation layer (3) edge passivation process directly applied on final strings just before lamination.

Review of: "At first glance, nanotube antennas give us the impression that they are similar to Dipole antennas designed in small dimensions"

Review of: "At first glance, nanotube antennas give us the impression that they are similar to Dipole antennas designed in small dimensions"

Compact broadband high‐gain dielectric rod antenna with air–dielectric hybrid design for millimetre‐wave applications

AbstractThis paper presents a compact, broadband, high‐gain dielectric rod antenna. By utilising an air–dielectric hybrid method for designing the radiating and matching sections, gradual variations in the average equivalent permittivity along the rod are achieved, and the mechanism of the method is analysed. This approach facilitates a smooth impedance transition from the feed to the air, resulting in good impedance matching characteristics. Additionally, the antenna is fed through a tapered double‐ridged waveguide (DRW) with a coaxial line to tapered DRW transition. The proposed antenna achieves an impressive impedance bandwidth of 90.2%, covering the entire K and Ka bands. The unique structure of the proposed dielectric rod significantly enhances the antenna's gain, reaching a maximum value of 17.86 dBi. With its small aperture and compact longitudinal dimensions, this antenna is suitable for applications in settings like the Space Environment Simulation Research Infrastructure (SESRI).

Microelectromechanical System Resonant Devices: A Guide for Design, Modeling and Testing

Microelectromechanical systems (MEMSs) are attracting increasing interest from the scientific community for the large variety of possible applications and for the continuous request from the market to improve performances, while keeping small dimensions and reduced costs. To be able to simulate a priori and in real time the dynamic response of resonant devices is then crucial to guide the mechanical design and to support the MEMSs industry. In this work, we propose a simplified modeling procedure able to reproduce the nonlinear dynamics of MEMS resonant devices of arbitrary geometry. We validate it through the fabrication and testing of a cantilever beam resonator functioning in the nonlinear regime and we employ it to design a ring resonator working in the linear regime. Despite the uncertainties of a fabrication process available in the university facility, we demonstrate the predictability of the model and the effectiveness of the proposed design procedure. The satisfactory agreement between numerical predictions and experimental data proves indeed the proposed a priori design tool based on reduced-order numerical models and opens the way to its practical applications in the MEMS industry.

Phenotypic Characters and Inheritance Tendency of Agronomic Traits in F1 Progeny of Chinese Cherry

Chinese cherry [Prunus. pseudocerasus Lindl., syn. Cerasus. pseudocerasus (Lindl.) G.Don], an economically important tetraploid fruit crop native to southwestern China, is celebrated as “the earliest fruit of spring”. Understanding the inheritance and heterosis of major agronomical traits is essential for advancing its breeding. In this study, we conducted a three-year observation and inheritance analysis of 32 economic traits in the reciprocal F1 populations (NH, n = 114; HN, n = 87) derived from Chinese cherry landraces “Nanzaohong” and “Hongfei”. The results revealed a broad segregation for all traits in F1 offspring. Fruit size exhibited an inheritance tendency toward smaller dimensions, with some individuals displaying extreme values (Fruit weight, HH = 3.90~12.15%) that highlighted the potential for selecting larger fruits. The hybrids showed a tendency for sweeter fruit flavor, with total soluble solids (RHm = 7.00~19.35%) and soluble sugar (RHm = 11.09% and 17.47%) exhibiting hybrid vigor, along with a decreasing tendency in titratable acid (RHm = −16.08~−1.05%). The flowering and fruiting phenology tended to occur earlier, with extremely early and late flowering lines offering the potential to extend the ornamental and harvesting periods. Fruit bitterness (H2 = 0.98 and 0.95) and fruit skin color (H2 = 0.93 and 0.89) displayed the highest heritability. Correlation analysis revealed strong internal correlations among trait categories, confirming the reliability of the data collection and analysis. Moreover, no significant differences were observed between the maternal and the paternal effect on the inheritance for agronomic traits attributes. This study systematically clarifies the inheritance trends of agronomic traits in Chinese cherry, providing a foundation for the rational selection of parental lines in breeding strategies and laying the groundwork for future molecular genetic research.

Reconfigurable logic-in-memory circuits with ferroelectric nanosheet field-effect transistors

Abstract To accommodate the requirements of small device dimensions and the application of ferroelectric field-effect transistors (FeFETs) in logic-in-memory circuits, we realize the reconfigurable logic-in-memory circuits with ferroelectric nanosheet field-effect transistors (FeNSFETs) through simulation. By evaluating the memory window and logic performances of the devices, it is demonstrated that the key to constructing logical functions are the magnitudes of the drain current at program (PGM) and erase (ERS) state when V G = 0 V. We find that appropriately increasing the number of nanosheets can enhance the current at PGM state, and appropriately increasing the write voltage can decrease the current at ERS state, which are both beneficial for the achievement of reconfigurable circuits. Thus, it is necessary to take into consideration the trade-offs between the process complexity, power consumption, and logical function realization. This work contributes to the prospective design for ferroelectric reconfigurable logic-in-memory circuits.

The dynamics of exchange traded funds: a geometrical and topological approach

Using a metric related to the returns correlation, a method is applied to the reconstruction of an economic space from Exchange-Traded Funds (ETFs) data. In the past, the same method was used in a geometrical analysis of times series of stock returns implying that the most of the systematic information of that market is contained in a space of small dimension. The same dimensional reduction was obtained using daily returns of 85 ETF securities in a time frame of more than 16 years. Having a metric defined in the space of ETF securities, a topological approach is used to define a complete network of ETFs and its corresponding Minimum Spanning Tree (MST). An outstanding separation of the two main classes of securities over the MST is uncovered. The dimensional reduction as well as the uncovered pattern in the topological structure, they both emerge from the data itself rather than from any modelling resolution.

Experimental and Numerical Study for a Horizontal Wastewater Heat Recovery System

This study aims to numerically and experimentally investigate the performance of a drain water heat recovery device. Consequently, a heat exchanger prototype was developed to integrate with classic rectangular shower trays of small dimensions. The proposed drain water heat recovery (DWHR) system was tested using a specially designed experimental stand. In addition, the experimental data were compared to numerical results based on Computational Fluid Dynamics (CFD) simulations. The values of effectiveness and Number of Transfer Units (NTU) achieved for the proposed DWHR system, based both on experimental and numerical data, are similar to those from the literature for analogous configurations of horizontal DWHR systems. Consequently, the heat exchanger prototype analyzed could represent a pertinent solution for heat recovery from drain shower water with minimum investment costs.

False Piezoresistive Effect Detection

Possibility of the use commercial carbon-polymer pastes for preparation thick-film resistors for linear strain sensors application was tested. The research showed that the polymer thick-film resistors are characterized by the piezoresistive effect up to 2% strain. For higher strain small cracks appeared in the resistive film. Presence of the cracks influenced resistance of the sensor. It is so called false piezoresistive effect. The cracks may cause instability of the sensor. Visual detection of the cracks is hardly possible because of their small dimensions. The indicator of cracks creation in resistive film was found.

Analysis of circularity metrology of small cylindrical workpiece with a segmenting scan method

Owing to eccentricity and inclination, circularity of a cylindrical workpiece cannot be measured precisely by a circularity measuring machine when the workpiece has a small dimension (diameter ≤ 3 mm). In this paper, with the aim of solving this problem, circularity metrology of a small cylindrical workpiece using a segmenting scanning method is analyzed. The cross-sectional circle of the cylinder is segmented into several equivalent arcs for measurement by a two-dimensional coordinate measuring machine (profilometer). The circularity contour is obtained by stitching together arc contours obtained by data processing of the coordinates. Different segmenting patterns for coordinate scanning are considered. Measurement results are presented for three segmentation patterns, with 8, 10, and 12 equal segments, respectively. These results are evaluated in terms of the matching coefficient between neighboring arc contours on circumferential stitching, the Euclidean distance between neighboring arc contours on radial stitching, and the curvature of the arcs. From these evaluations, it is found that as the number of segments is increased, the matching coefficient increases from 0.14 to 0.50, the Euclidean distance decreases from 32 nm to 26 nm, and the curvature becomes close to the standard value.

An enhanced bioactive chitosan-modified microemulsion for mucosal healing of ulcerative colitis

The intestinal mucus layer plays a crucial role in the systemic absorption of drugs. While penetration through this layer traditionally constitutes a pivotal phase in drug absorption, the approach for treating ulcerative colitis (UC) shifts towards facilitating the direct delivery of drugs to the colon. In this study, we engineered a chitosan-modified microemulsion encapsulated nobiletin (NOB-CS-ME) characterized by small particle dimensions and positive charge specifically, designed to enable targeted delivery. In vitro experiments demonstrated that this NOB-CS-ME effectively became less into the intestinal mucus layer, thus achieving successful escape of the intestinal mucus barrier absorption. After circumventing this barrier, NOB-CS-ME exhibited heightened cellular uptake by colonic epithelial cells, displaying an approximately 1.3-fold increase compared to the unmodified microemulsion. Collectively, these observations imply enhanced drug bioavailability, potentially resulting in more efficacious mucosal healing, providing a promising avenue for natural small-molecule drug delivery in UC treatment.

Automating life science labs at the single-cell level through precise ultrasonic liquid sample ejection: PULSE

Laboratory automation technologies have revolutionized biomedical research. However, the availability of automation solutions at the single-cell level remains scarce, primarily owing to the inherent challenges of handling cells with such small dimensions in a precise, biocompatible manner. Here, we present a single-cell-level laboratory automation solution that configures various experiments onto standardized, microscale test-tube matrices via our precise ultrasonic liquid sample ejection technology, known as PULSE. PULSE enables the transformation of titer plates into microdroplet arrays by printing nanodrops and single cells acoustically in a programmable, scalable, and biocompatible manner. Unlike pipetting robots, PULSE enables researchers to conduct biological experiments using single cells as anchoring points (e.g., 1 cell vs. 1000 cells per “tube”), achieving higher resolution and potentially more relevant data for modeling and downstream analyses. We demonstrate the ability of PULSE to perform biofabrication, precision gating, and deterministic array barcoding via preallocated droplet-addressable primers. Single cells can be gently printed at a speed range of 5–20 cell⋅s−1 with an accuracy of 90.5–97.7%, which can then adhere to the substrate and grow for up to 72 h while preserving cell integrity. In the deterministic barcoding experiment, 95.6% barcoding accuracy and 2.7% barcode hopping were observed by comparing the phenotypic data with known genotypic data from two types of single cells. Our PULSE platform allows for precise and dynamic analyses by automating experiments at the single-cell level, offering researchers a powerful tool in biomedical research.

Polarization-insensitive bifocal metalenses by combining nanoimprint lithography and atomic layer deposition in the visible spectrum

Multifocal lenses are essential components for microscopy, spectroscopic detection, and optical trapping. Benefiting from the unprecedented capability of metasurfaces in light control, metalenses are able to provide multi-foci functionality with a more compact footprint, making them attractive alternatives to traditional bulky lenses. However, current manufacturing techniques encounter some challenges, including low throughput, high cost, and limited patterning areas. Here, we demonstrate the wafer-scale, low-cost, and high-throughput production of polarization-insensitive bifocal metalenses at a wavelength of 450 nm by combining nanoimprint lithography and atomic layer deposition. The nanoimprint process is simplified by using the imprinted resin itself as meta-atoms, which exhibit high aspect ratios (∼10:1) and small critical dimensions (∼90 nm). The effective refractive index of the meta-atoms is increased through atomic layer deposition of the high-index TiO2 film, providing 0–1.5π sufficient phase coverage. Metalenses with diameters of 480 μm are fabricated on the silica substrate, exhibiting two diffraction-limited focal spots along the optical axis. Moreover, the fabricated metalenses demonstrate the polarization-insensitive feature under various polarization states. The fabrication process presented in this Letter paves the way for large-scale and low-cost production of versatile metasurfaces operating in the visible or shorter spectrum.

Interface-mediated nano-downsizing for concentrated black phosphorene dispersions in volatile systems

Black phosphorene (BP) shows great potential as a versatile two-dimensional material. Its scalable preparation and practical applications often rely on processable forms such as dispersions. However, the inherent instability of concentrated BP dispersions and the use of high-boiling point solvents pose significant challenges, particularly during solvent removal. Here, we introduce an interface-mediated nano-downsizing strategy to achieve uniformly small lateral dimensions in few-layered BP nanosheets. This method enables the efficient and scalable preparation of concentrated phytic acid (PA)-stabilized BP dispersions in low-boiling point solvents such as acetone. These dispersions remain stable for at least 18 days in nitrogen and 8 days in air, demonstrating efficient photothermal conversion (45.8 %) and excellent photothermal stability. The volatile system facilitates the rapid preparation of uniform BP coatings on various substrates at room temperature. This work provides a general method for preparing concentrated nano-dispersions in volatile solvents, optimizing their performance for various applications.

Latent-Energy-Based NNs: An interpretable Neural Network architecture for model-order reduction of nonlinear statics in solid mechanics

Nonlinear mechanical systems can exhibit non-uniqueness of the displacement field in response to a force field, which is related to the non-convexity of strain energy. This work proposes a Neural Network-based surrogate model capable of capturing this phenomenon while introducing an energy in a latent space of small dimension, that preserves the topology of the strain energy; this feature is a novelty with respect to the state of the art. It is exemplified on two mechanical systems of simple geometry, but challenging strong nonlinearities. The proposed architecture offers an additional advantage over existing ones: it can be used to infer both displacements from forces, or forces from displacements, without being trained in both ways.

High gain nested dielectric resonator rectenna based on higher order mode and magneto-electric dipole theory

In this paper, a high-gain nested dielectric resonator rectenna operating at 5.8 GHz based on the magneto-electric dipole theory is proposed. A nested structure is employed to achieve the required resonant frequency in a small dimension. And the higher order HE21δ mode of the dielectric resonator antenna (DRA) is excited by a vertical coaxial probe feeding, which is equated to a horizontal array of crossed magnetic dipoles, thus enhancing the gain. Then, two vertical metal posts are embedded inside the DRA, serving as electric dipoles to form a magneto-electric dipole array in conjunction with the magnetic dipoles, which suppress the excessive lobes of the DRA in HE21δ mode and hence enhance the maximum gain of the DRA to 9.8 dBi. A rectifier circuit with harmonic suppression is designed. By adding a short-circuit microstrip transmission line to the rectifier circuit, the second harmonic with infinite impedance is suppressed and reflected back to the diode for secondary rectification. The designed rectifier circuit is connected to the DRA to form a rectenna. The test result shows that the rectenna obtains a peak conversion efficiency of 43.9 % and an output voltage of 1.95 V at 5.8 GHz, which is suitable for wireless energy harvesting.

Resistance standards with very small calculable AC-DC difference at frequencies up to 2 MHz for the calibration of precision LCR meters

Abstract We have developed novel impedance standards based on thin-film surface mount device (SMD) resistors. Due to the small dimensions of such resistors, the frequency dependence is very small and can be calculated from quantities that can be either measured or numerically calculated. For nominal resistance values in the 10 kΩ range, as for our application, the DC and AC properties of a single thin-film SMD resistor are not sufficient but can be greatly improved by connecting several thin-film SMD resistors in series. Then the calculated frequency dependence at frequencies up to 2 MHz amounts to only a few parts per million of the DC value, which is about four orders of magnitude smaller than for all conventional calculable AC-DC resistors with a similar nominal DC value. A precision inductance-capacitance-resistance (LCR) meter for frequencies up to 2 MHz, which has a resolution and a reproducibility of a few parts per million but a systematic uncertainty of up to 3000 parts per million, is used to measure two very different SMD-based resistance standards. This enables the verification of the model calculation as well as the calibration of the LCR meter and the correction of its systematic effects, both with a relative uncertainty of a few parts per million in the whole frequency range. This boost in precision enables new applications in this frequency range such as the verification of conventional calculable resistance standards, the calibration of impedance standards, and future measurements of the quantum Hall resistance.We have developed novel impedance standards based on thin-film surface mount device

TMOD-09. NEWLY DESIGNED TUMOR TREATING FIELDS (TTFIELDS) ARRAYS FOR THE MOUSE HEAD DEMONSTRATE EFFICACY FOR TREATMENT OF GLIOBLASTOMA

Abstract Tumor Treating Fields (TTFields) therapy is a cancer treatment modality based on continuous, non-invasive delivery of electric fields. TTFields therapy is approved for treatment of glioblastoma (GBM), delivered to the patient’s brain by two array pairs placed on the scalp. Further research in animals to expand the knowledge regarding TTFields treatment of GBM is limited, as this is mainly performed in mouse models and arrays for application of TTFields to the mouse head are lacking. The small dimensions and specific geometries of the mouse head make the development of such arrays challenging. The aim of this study was to design arrays that will allow efficient and stable delivery of TTFields to the mouse head. To overcome the small head size, we developed a layout with two arrays situated on the head of the mouse, each divided into two smaller disks, and positioned opposite two arrays on the torso. We identified a thin and transparent adhesive tape (facilitating correct array positioning) with good tackiness and easy removal (without leaving residual adhesive on the skin). The arrays met the minimum treatment requirements: current ≥ 50 mA, usage ≥ 75%, field intensity ≥ 1 V/cm RMS. We then conducted an efficacy study with the new arrays, using GL-261 GBM cells intracranially injected into C57BL/6 mice. Treatment with sham-heat (control) or TTFields was initiated 11 days following tumor inoculation and maintained continuously for 12 days. Efficacy was measured via magnetic resonance imaging (MRI) of tumor volume, showing a decrease of 31% at treatment end in TTFields-treated mice versus the control. Overall, the new arrays are flexible, strongly adherent, deliver TTFields at a sufficient intensity, and showed efficacy for treating GBM in mice.