Shape Control Research Articles

Size, Shape and Composition Control of Metallic Colloidal Nanoparticles for the Design of Heterogeneous Catalysts

Metal supported catalysts play a pivotal role in various industrial processes, yet conventional preparation methods such as impregnation or coprecipitation lack precision in controlling critical parameters like particle size, morphology, and composition. The colloidal synthesis proved to be an excellent route for the rational adjustment of these parameters, allowing to establish structure‐performance correlations for smart catalyst design. This review explore the common strategies employed for the fine tuning of size, shape, and composition of colloidal nanoparticles used as heterogeneous catalysts. Since the colloidal route involves the use of stabilizing agents, different strategies for their removal are discussed together with insights into their effects in catalysis. Furthermore, common strategies for the deposition of preformed nanoparticles are presented. . In addition, the modifications in the geometric and electronic properties and their impact in the catalytic properties are described. To conclude, current applications, challenges, and future perspectives of metal supported nanoparticles as heterogenous catalysts are discussed.

Stable, recyclable, hybrid ionic-electronic conductive hydrogels with non-covalent networks enhanced by bagasse cellulose nanofibrils for wearable sensors.

Conductive hydrogels are utilized in flexible sensors due to their high-water content, excellent elasticity, and shape controllability. However, the sharp increase in resistance of this material under enormous strain leads to instability in the sensing process. This study presents a straightforward method for creating a stable, recyclable, hybrid ionic-electronic conductive (HIEC) hydrogel via a simple one-pot strategy using polyvinyl alcohol (PVA), bagasse cellulose nanofibrils (CNF), and graphene(G) with sodium dodecylbenzene sulfonate (SDBS). The SDBS/G hemimicelles are formed through hydrophobic and π-π stacking interactions between SDBS and G, enhancing the dispersibility of G. Then SDBS/G hemimicelles were integrated into a non-covalent cross-linking network from CNF and PVA, which ensures recyclability and stability. The CNF-PVA-Graphene (CPG) hydrogel exhibited high and stable sensing sensitivity (average gauge factor up to 1.99), high conductivity (0.36S/m), low graphene concentration (0.16wt%), low detection limit (1%), and fast response time (0.17s). The sensor can detect large (wrist and knee) and small (pulse and laryngeal prominence) body movements. After recycling, the hydrogel sensors maintained high conductivity sensitivity (average gauge factor up to 1.01) and good tensile properties (360% strain). This study introduces a new approach of hybrid conductive biomass-based hydrogel sensors for precisely monitoring human movements.

Influence of aperture shape controller settings on dose distribution and treatment efficiency in lung stereotactic body radiation therapy with a 10 MV flattening filter-free beam.

We evaluated the effects of different aperture shape controller (ASC) settings on the dose distribution and delivery efficiency of lung stereotactic body radiotherapy (SBRT) using volumetric modulated arc therapy (VMAT) with a 10 MV flattening filter-free (FFF) beam. Ten lung SBRT cases with breath-holding were retrospectively analyzed by comparing plans with no-ASC and those with 5 ASC settings (very low, low, moderate, high, and very high). The gross tumor volume (GTV) coverage: D98% (minimum dose to 98% of the volume), target conformity index (CI), gradient index (GI), D2cm (dose maximum at 2cm from the planning target volume), lung dose, monitor unit (MU), modulated complexity score for VMAT (MCSv), and delivery time were evaluated. Compared with the no-ASC setting, there were no significant differences in GTV coverage, GI, or D2cm in the different ASC settings. A very high ASC setting resulted in a slight increase in the mean lung dose metrics. On average, MU and delivery times were significantly reduced by approximately 200 MU and 5.0 s with very high ASC settings compared to the no-ASC setting. Plan complexity decreased as the ASC increased, with the very high ASC setting showing the highest MCSv values. This study suggests that the very high ASC setting may improve the delivery efficiency for lung SBRT using VMAT with the 10 MV FFF beam under breath-holding while maintaining comparable dose distributions and target coverage.

Three-dimensional temperature field distribution of thin medium plate during finishing rolling and its effect on shape control

Three-dimensional temperature field distribution of thin medium plate during finishing rolling and its effect on shape control

Comparison of Shape Control Accuracy and Interfacial Diffusion Behavior Between 304 Stainless Steel Core and ZrO2 Core in Hot Isostatic Pressing

Comparison of Shape Control Accuracy and Interfacial Diffusion Behavior Between 304 Stainless Steel Core and ZrO2 Core in Hot Isostatic Pressing

High-Uniformity, Shape-Controlled Silicon Nanowires for Enhanced Performance in Optoelectronic Devices.

Silicon nanowires (Si NWs) have attracted considerable interest owing to their distinctive properties, which render them promising candidates for a wide range of advanced applications in electronics, photonics, energy storage, and sensing. However, challenges in achieving large-scale production, high uniformity, and shape control limit their practical use. This study presents a novel fabrication approach combining nanoimprint lithography, nanotransfer printing, and metal-assisted chemical etching to produce highly uniform and shape-controlled Si NW arrays. By optimizing the process parameters, Si NWs with various diameters (100, 200, and 400nm) are successfully fabricated on 6-inch wafers, achieving high uniformity confirmed through statistical and surface reflection analyses. Furthermore, a conformal coating of titanium nitride on the uniform Si NWs enables broadband absorption with average absorption of 75% in the wavelength range from 250 to 2500nm, demonstrating their potential for next-generation optoelectronic devices. These findings provide valuable insights for the scalable production of Si NWs and their integration into high-performance electronic systems.

Bio-inspired Octopus-mimicking Soft Robotic Grasping System

Octopus-inspired soft robots have emerged as a promising field of research, drawing inspiration from the remarkable dexterity and adaptability of this marine creature. Their ability to manipulate objects in complex environments, coupled with their soft, compliant bodies, offers significant advantages over traditional rigid robots. This paper provides a comprehensive overview of recent advancements in the design and development of octopus-inspired soft robots, focusing on shape control, grasping strategies, and potential applications. This paper presents a comprehensive review of recent advancements in biomimetic robotic design, focusing on octopus-inspired soft robots and soft grippers. This paper discusses various shape control algorithms and modeling methods for octopus-inspired soft manipulators, highlighting their applications in highly flexible and complex grasping tasks. The paper explores grasping planning strategies for soft grippers, such as force equilibrium and minimum grasping force control, to achieve precise grasping of diverse objects. Furthermore, this paper present various design schemes based on soft materials and actuation techniques, including tendon-driven and pneumatic actuation, each with its own structural and performance advantages. This paper provides theoretical support and practical guidance for the further development and optimization of octopus-inspired soft robots.

Role of polymer graft stiffness in electrostatic-driven self-assembly of nanoparticles in solutions.

Self-assembly of nanoparticles (NPs) in solution has garnered tremendous attention among researchers because of their electrical, chemical, and optoelectronic properties at the macroscale with potential applications in bio-imaging, bio-medicine, and therapeutics. Control of size, shape, and composition at the nanoscale is important in tuning the material's bulk properties. The grafting of NPs with polymers enables us to tune such bulk material properties at the nano level by controlling their assemblies, especially in solutions. The stiffness of grafts plays a crucial role in tuning the self-assembly of spherical NPs grafted with polyions (PGNs). Many recent studies based on single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) showed the potential applications of such assemblies. In this work, we have performed coarse-grained molecular dynamics (MD) simulations to understand the charge-driven self-assembly of PGNs by varying stiffness of polymer grafts, the grafting density, and graft length. Self-assembly of these PGNs leads to the formation of different structures driven by the rigidity of polyion chains and the electrostatic interactions. A dramatic change in morphological transitions can be achieved, ranging from rings, strings, and percolated structures and ordered to disordered aggregates by tuning the control parameters. The percolated structures form disordered structures upon annealing with potential applications in thermal under filling, neuromorphic devices, and biological systems including drug delivery, and therapeutics.

Integration of silver nanostructures in wireless sensor networks for enhanced biochemical sensing.

Integrating noble metal nanostructures, specifically silver nanoparticles, into sensor designs has proven to enhance sensor performance across key metrics, including response time, stability, and sensitivity. However, a critical gap remains in understanding the unique contributions of various synthesis parameters on these enhancements. This study addresses this gap by examining how factors such as temperature, growth time, and choice of capping agents influence nanostructure shape and size, optimizing sensor performance for diverse conditions. Using silver nitrate and sodium borohydride, silver seed particles were created, followed by controlled growth in a solution containing additional silver ions. The size and morphology of the resulting nanostructures were regulated to achieve optimal properties for biochemical sensing in wireless sensor networks. Results demonstrated that embedding these nanostructures in Polyvinyl Alcohol (PVA) matrices led to superior stability, maintaining 93% effectiveness over 30days compared to 70% in Polyethylene Glycol (PEG). Performance metrics revealed significant improvements: reduced response times (1.2ms vs. 1.5ms at zero analyte concentration) and faster responses at higher analyte levels (0.2ms). These outcomes confirm that higher synthesis temperatures and precise shape control contribute to larger, more stable nanostructures.The enhanced stability and responsiveness underscore the potential of noble metal nanostructures for scalable and durable sensor applications, offering a significant advancement over current methods.

The Role of Light Irradiation and Dendrimer Generation in Directing Electrostatic Self-Assembly.

pH-responsive polyamidoamine (PAMAM) dendrimers are used as well-defined building blocks to design light-switchable nano-assemblies in solution. The complex interplay between the photoresponsive di-anionic azo dye Acid Yellow 38 (AY38) and the cationic PAMAM dendrimers of different generations is presented in this study. Electrostatic self-assembly involving secondary dipole-dipole interactions provides well-defined assemblies within a broad size range (10 nm-1 μm) with various shapes. The size and shape of these assemblies were determined using dynamic and static light scattering (DLS/SLS) and small-angle neutron scattering (SANS); ζ-potential measurements were performed to elucidate the charge characteristics, revealing the effective surface charge density of the nano-objects as an important parameter in the size and shape control. UV-vis spectroscopy and isothermal titration calorimetry (ITC) were employed to investigate the interaction on a molecular level and from a thermodynamic point of view. The results show that the amount of isomerized cis dye depends on the dendrimer generation because of a photoprotective effect through electrostatics for lower generations and through dipole-dipole interactions for higher generations; as the cis dye and trans dye bind with different strength, the amount of cis dye then again encodes the charge density and thereby the particle size and shape.

Photoinduced Shape Changes of Giant Vesicles Comprising Phospholipids and Azobenzene-Containing Cationic Amphiphiles.

For the development of new functional materials for various applications, such as drug or gene delivery and environmental remediation, the relationship between function and morphology has been considered an important aspect for controlling affinity to the targets. However, there are only a few reports on this relationship because the molecular strategy for the precise control of vesicle shape has been restricted. Herein, we report the photocontrol of vesicle shape using azobenzene-containing amphiphilic switches. The addition of the photoswitches to vesicles composed of phospholipids yielded non-spherical vesicles. They exhibited reversible deformation between a non-spherical and spherical shape in response to ultraviolet and visible light illumination, respectively. From the results of the 1H NMR analyses, fluorescence spectra of the environmentally responsive probes, and Π-A isotherm measurements, the reversible photoresponsivity can be attributed to the changes in the vesicular membrane structures caused by migration of the photoswitches between the aqueous phase and membrane through their photoisomerization.

Engineering the Thermal and Energy-Storage Properties in Quantum Dots Using Dominant Faceting: The Case Study of Silicon.

The storage and release of energy is an economic cornerstone. In quantum dots (QDs), energy storage is mostly governed by their surfaces, in particular by surface chemistry and faceting. The impact of surface free energy (SFE) through surface faceting has already been studied in QDs. Here, we introduce dominant faceting representing the structural order of the surface. In particular, we propose that realistic QDs attain complicated polyhedral quasi-spherical shapes while keeping the dominance of a certain type of facet. The type of dominant facet determines the rates of surface-related processes. Therefore, by connecting dominant faceting with SFE, trends analogical to bulk material are kept despite the lack of evident microscopic shape control. To demonstrate the applicability of dominant faceting, we synthesize sets of silicon QDs with sizes around 5 nm and classify them based on increasing SFE of the corresponding analytic geometrical models, using a detailed surface chemistry analysis. Total energies released during oxidation of the synthesized QDs reach the theoretical limit, unlike in the reference, "large" (>100 nm) silicon nanoparticles, which release about 15% less energy. Next, we perform a comprehensive experimental study of dehydrogenation and thermal oxidation of the synthesized QDs in the temperature range of 25-1100 °C, identifying SFE as the key factor determining their thermal stability and surface reactivity. In particular, four distinctive stages of energy release were observed with onset temperatures ranging between 140 and 250 °C, ≈500 and 650-700 °C, respectively, for the SFE-differing samples. Finally, the thermal oxidation of the synthesized QDs is completed at lower temperatures with increasing SFE, decreasing from 1065 to 970 °C and being > 150 °C lower in QDs than in the larger reference nanoparticles. Therefore, despite a rich mixture of features, our description based on linking dominant faceting with SFE allows us to fully explain all the observed trends, demonstrating both the potential of SFE-based engineering of energy-storage properties in QDs and the prospects of silicon QDs as an energy-storage material.

Complementary Reducing Agents are Responsible for Temporally Distinct Nucleation and Growth Phases During the Polyol Synthesis of Ag Nanocubes

AbstractEthylene glycol or one of its oxidation products are believed to serve as reducing agents in the shape‐controlled synthesis of Ag nanocubes (NCs) by the polyol process. The identity of end‐groups of polyvinylpyrrolidone (PVP) impacts shape control with alcohol and aldehyde moieties serving as a primary Ag reducing agent. We explored the role of PVP end‐groups in the polyol process by measuring the dependence of particle number density of Ag NCs produced on the initial concentration(s) of Ag and PVP using small angle x‐ray scattering and statistically large particle size distributions analyzed by scanning electron microscopy. The number density of Ag NCs is strongly dependent on the starting concentration of PVP chains demonstrating PVP end‐groups play an important role in the nucleation of NCs. The concentration of Ag+ is 2 orders of magnitude higher than the end‐groups suggesting ethylene glycol must participate in the reduction of Ag+ during growth. Perturbation experiments and analysis of resultant particle size distribution reveal nucleation is fast relative to growth of NCs, reinforcing the synergy between PVP end‐groups and ethylene glycol. The evidence demonstrates PVP end‐groups and ethylene glycol are tandem reducing agents operative in temporally distinct phases of the polyol synthesis of Ag NCs.

Effect of mixed phase with shape control on lithium ions transport during conversion reaction in the manganese oxide anode

Effect of mixed phase with shape control on lithium ions transport during conversion reaction in the manganese oxide anode

Efficient layer-building approach for promising cold spray additive manufacturing

Cold spray has demonstrated superior manufacturing efficiencies in geometric forming, which positions it as a significant process in metal additive manufacturing technology. Cold spray additive manufacturing (CSAM) achieves geometric forming by employing a layer-by-layer construction methodology. However, the current challenge lies in the lack of evaluation and management of the efficiency in layer-building, leading to potential conflicts between manufacturing efficiency and forming accuracy. To address this issue, this paper proposes a layer-building approach based on the forming characteristics of cold-sprayed single-track to enhance the efficiency of CSAM. The study initially analyzes the deposition efficiency and deposition rate resulting from various process parameters, as demonstrated by the geometry characteristics of the single-track. Furthermore, the geometry and efficiency models of CSAM single-track based on Gaussian distribution are developed. Subsequently, the study conducts the selection of efficient single-tracks and optimization of layer-building parameters based on the single-track model. Finally, both the simulation and experimental validations are performed. The results indicate that the proposed approach enables the continuous building of CSAM single-layers with high efficiency. The optimal deposition rate and deposition efficiency of the layer-building can reach 4.942 cm3/min and 73.79 %, respectively. Additionally, the model offers predictions and control of the geometrical shape during the CSAM. This implies that the proposed approach enhances CSAM as an efficient layer-by-layer additive manufacturing process for 3D shape forming.

Learning Graph Dynamics with Interaction Effects Propagation for Deformable Linear Objects Shape Control

Learning Graph Dynamics with Interaction Effects Propagation for Deformable Linear Objects Shape Control

Synthesis of shape-tunable PbZrTiO3 nanocrystals with lattice variations for piezoelectric energy harvesting and human motion detection.

PbZr0.7Ti0.3O3 cubes with tunable sizes and cuboids have been hydrothermally synthesized. PbZrTiO3 cubes with three different Zr : Ti atomic percentages were also prepared. Analysis of synchrotron X-ray diffraction (XRD) patterns reveals the presence of two lattice components for these samples. Fast Fourier Transform (FFT) processing of high-resolution transmission electron microscopy (HR-TEM) images shows discernible lattice spot differences between the inner bulk and surface layer region for a PbZr0.7Ti0.3O3 cube, while a cuboid has distinct lattice spot deviations. The lattice variations yield different dielectric constant numbers for these two samples, despite being bound by the same crystal faces. The PbZrTiO3 crystals give size- and composition-dependent band gaps. Cuboids show notably larger piezoelectric and ferroelectric responses than cubes. Piezoelectric nanogenerators (PENGs) containing 30 wt% cuboids produce the highest open-circuit voltage of 20.36 V and short-circuit current of 2300 nA. The PENGs harvest energy through bending/releasing cycles to power devices and show photothermal pyroelectric activity. Moreover, a single 30 wt% cuboid PENG device integrated into a shoe insole can deliver an impressive 96.8% accuracy for human motion detection using a machine learning approach. This work illustrates that considerable lattice variation through crystal shape control is effective in enhancing material properties.

Shape control of space reflector integrated by sub-reflectors utilizing adjustable solar radiation pressure force

Shape control of space reflector integrated by sub-reflectors utilizing adjustable solar radiation pressure force

Energy Shaping Control in Underactuated Robot Systems with Underactuation Degree Two

Energy Shaping Control in Underactuated Robot Systems with Underactuation Degree Two

Metal transfer and forming behavior of bypass-coupled variable polarity plasma arc additive manufacturing

This study proposes a novel bypass-coupled variable-polarity plasma arc additive manufacturing process. This process enables independent control of the main current, bypass current, and their polarities, thereby achieving decoupled control of thermal input to the deposited layers and wire melting. Additionally, the variable polarity effectively removes the oxide film on the surface of aluminum alloys, improving defects in aluminum alloy additive manufacturing. The research results indicate that the bypass-coupled variable-polarity plasma arc additive manufacturing presents different metal transfer forms compared to conventional arc additive manufacturing (MIG/TIG arc heat sources). The droplet transfer behavior manifests in various forms at different wire heights, including droplet transfer, Intermittent bridging transfer, and complete bridging transfer. Notably, the complete bridging transfer results in short metal bridge, which weakens the influence of the coupled arc magnetic field and provides a wider process window for shaping. A detailed analysis of the effects of main and bypass EN/EP currents on the formation morphology reveals that the influence of the main EN current on the width of the deposited layer is twice that of the bypass EN current. By adjusting the main EN current, the remelting depth can be effectively controlled, allowing for precise control over the morphology of the deposited layers. This study demonstrates the potential of this process to enhance deposition efficiency, reduce thermal input, and achieve effective shaping control.