Complex Three-dimensional Structures Research Articles

A Methodological Framework for Assessing the Influence of Process Parameters on Strand Stability and Functional Performance in Fused Filament Fabrication.

With an ever-increasing material and design space available for Fused Filament Fabrication (FFF) technology, fabrication of complex three-dimensional structures with functional performance offers unique opportunities for product customization and performance-driven design. However, ensuring the quality and functionality of FFF-printed parts remains a significant challenge, as material-, process-, and system-level factors introduce variability and potentially hinder the translation of bulk material properties in the respective FFF counterparts. To this end, the present study presents a methodological framework for assessing the influence of process parameters on FFF strand stability and functional performance through a systematic analysis of FFF structural elements (1D stacks of FFF strands and 3D blocks), in terms of dimensional deviation from nominal geometry and resistivity, corresponding to the printability and functionality attributes, respectively. The influence of printing parameters on strand stability was investigated in terms of dimensional accuracy and surface morphology, employing optical microscopy and micro-computed tomography (mCT) for dimensional deviation analysis. In parallel, electrical resistance measurements were carried out to assess the effect of different process parameter combinations and toolpath patterns on functional performance. In low-level structural elements, strand height (H) was found to induce the greatest influence on FFF strand dimensional accuracy and resistivity, with higher H values leading to a reduction in resistivity of up to 38% in comparison with filament feedstock; however, this occurred at the cost of increased dimensional deviation. At higher structural levels, the overall effect of process parameters was found to be less pronounced, indicating that the translation of 1D strand properties to 3D blocks is subject to a trade-off due to competing mechanisms that facilitate/hinder current flow. Overall, the proposed framework enables the quantification of the influence of process parameters on the selected response variables, contributing to the development of standard operating procedures and recommendations for selecting optimal process parameters to achieve the desired process stability and functional performance in FFF.

Frequency-aware robust multidimensional information fusion framework for remote sensing image segmentation

Urban scene image segmentation is an important research area in high-resolution remote sensing image processing. However, due to its complex three-dimensional structure, interference factors such as occlusion, shadow, intra-class inconsistency, and inter-class indistinction affect segmentation performance. Many methods have combined local and global information using CNNs and Transformers to achieve high performance in remote sensing image segmentation tasks. However, these methods are not stable when dealing with these interference factors. Recent studies have found that semantic segmentation is highly sensitive to frequency information, so we introduced frequency information to make the model learn more comprehensively about different categories of targets from multiple dimensions. By modeling the target with local features, global information, and frequency information, the target features can be learned in multiple dimensions to reduce the impact of interference factors on the model and improve its robustness. In this paper, we consider frequency information in addition to combining CNNs and Transformers for modeling and propose a Multidimensional Information Fusion Network (MIFNet) for high-resolution remote sensing image segmentation of urban scenes. Specifically, we design an information fusion Transformer module that can adaptively associate local features, global semantic information, and frequency information and a relevant semantic aggregation module for aggregating features at different scales to construct the decoder. By aggregating image features at different depths, the specific representation of the target and the correlation between targets can be modeled in multiple dimensions, allowing the network to better recognize and understand the features of each class of targets to resist various interference factors that affect segmentation performance. We conducted extensive ablation experiments and comparative experiments on the ISPRS Vaihingen and ISPRS Potsdam benchmarks to verify our proposed method. In a large number of experiments, our method achieved the best results, with 84.53% and 87.3% mIoU scores on the Vaihingen and Potsdam datasets, respectively, proving the superiority of our method. The source code will be available at https://github.com/JunyuFan/MIFNet.

Hydrothermal syntheses of d10-based Zn(II) and Cd(II) metal–organic frameworks for the catalysis of the Knoevenagel condensation

Metal–organic frameworks (MOFs) are compounds that feature metal clusters coordinated with organic ligands, forming impressive structures and properties. In this study, two MOFs of Zn(II) and Cd(II) were synthesized using the organic compound 5‑hydroxy-2-pyrazinecarboxylic acid, forming Zn-MOF and Cd-MOF. To better understand the intricate structures of these MOFs, single-crystal X-ray crystallography was used to characterize their respective structures. The results showed that both MOFs have complex three-dimensional supramolecular structures that are highly symmetric and contain water molecules. Additionally, topological analysis of the MOFs indicated that they have a zeolite-like structure. The Hirshfeld surfaces analysis revealed that both crystal structures could preferentially interact with other molecules through hydrogen bonds. The MOFs were found to have a direct band gap, with the energy observed to be 2.44 and 2.71 eV for the Zn-MOF and Cd-MOF systems, respectively. The hydrogen bond formation ability of the MOFs, in combination with their low band gap energy, make them highly suitable for use in the Knoevenagel condensation reaction in water. Overall, the results of this study provide important insights into the unique properties and potential applications of MOFs in diverse fields.

Wet classification behavior of bidisperse colloidal particles through nanofibrous membrane

Membrane separation has emerged as a prominent method for the removal of undesirable particles from wastewater in the field of water treatment. However, classification of particles with varying sizes by membrane is still poorly understood, warranting further exploration. This study is to investigate the wet classification behaviors of polydisperse particles using a nanofibrous membrane that features a complex three-dimensional network structure and high porosity. The experimental results demonstrate that the nanofibrous membrane is effective in retaining larger particles, while its high porosity facilitates the smooth passage of smaller particles. To clarify the classification mechanism, we analyzed the filtration model and employed SEM images taken at different stages of the process to investigate the retention behavior of larger particles. The filtration of larger particles through microfiltration membrane exhibited a cake filtration model. The blockage of large particles on the membrane surface formed a cake layer, significantly reducing the filtration rate. Conversely, the nanofibrous membrane exhibited continuous intermediate blocking filtration at pH 11, resulting in effective retention of larger particles inside the membrane rather than solely on membrane surface. This enabled better utilization of the pore space within the nanofibrous membrane, thus highlighting it as a potential area for future research.

2D or not 2D? Mapping the in-depth inclination of the collagen fibers of the corneoscleral shell

The collagen fibers of the corneoscleral shell play a central role in the eye mechanical behavior. Although it is well-known that these fibers form a complex three-dimensional interwoven structure, biomechanical and microstructural studies often assume that the fibers are aligned in-plane with the tissues. This is convenient as it removes the out-of-plane components and allows focusing on the 2D maps of in-plane fiber organization that are often quite complex. The simplification, however, risks missing potentially important aspects of the tissue architecture and mechanics. In the cornea, for instance, fibers with high in-depth inclination have been shown to be mechanically important. Outside the cornea, the in-depth fiber orientations have not been characterized, preventing a deeper understanding of their potential roles. Our goal was to characterize in-depth collagen fiber organization over the whole corneoscleral shell. Seven sheep whole-globe axial sections from eyes fixed at an IOP of 50 mmHg were imaged using polarized light microscopy to measure collagen fiber orientations and density. In-depth fiber orientation distributions and anisotropy (degree of fiber alignment) accounting for fiber density were quantified over the whole sclera and in 15 regions: central cornea, peripheral cornea, limbus, anterior equator, equator, posterior equator, posterior sclera and peripapillary sclera on both nasal and temporal sides. Orientation distributions were fitted using a combination of a uniform distribution and a sum of π-periodic von Mises distributions, each with three parameters: primary orientation μ, fiber concentration factor k, and weighting factor a. To study the features of fibers that are not in-plane, i.e., fiber inclination, we quantified the percentage of inclined fibers and the range of inclination angles (half width at half maximum of inclination angle distribution). Our measurements showed that the fibers were not uniformly in-plane but exhibited instead a wide range of in-depth orientations, with fibers significantly more aligned in-plane in the anterior parts of the globe. We found that fitting the orientation distributions required between one and three π-periodic von Mises distributions with different primary orientations and fiber concentration factors. Regions of the posterior globe, particularly on the temporal side, had a larger percentage of inclined fibers and a larger range of inclination angles than anterior and equatorial regions. Variations of orientation distributions and anisotropies may imply varying out-of-plane tissue mechanical properties around the eye globe. Out-of-plane fibers could indicate fiber interweaving, not necessarily long, inclined fibers. Effects of small-scale fiber undulations, or crimp, were minimized by using tissues from eyes at high IOPs. These fiber features also play a role in tissue stiffness and stability and are therefore also important experimental information.

Overcoming Complex Analytical Challenges Posed by Targeted Multispecific Antibody Cancer Therapeutics

Complex multispecific antibodies overcome the limitations of standard monoclonal antibodies (mAbs), and have complex three-dimensional structures, greater heterogeneity, and often novel disulfide linkages and unusual post-translational modifications. As a result, the comprehensive characterization essential to the development of cost-effective manufacturing processes and safe and efficacious cancer treatments is much more challenging using traditional analytical instruments and techniques. Fortunately, there are new solutions available that provide fast results, often with greater sensitivity and resolution, even for these novel, complex molecules. The application of various new methods and instruments for the analysis of multispecifics is discussed as a means of highlighting their ability to facilitate the development of these important new modalities.

Reliability of Cone Bean Weight-Bearing Measurements of the Postoperative Outcome of Total Ankle Arthroplasties and Inter-Method Reliability with Respect to the Weight Bearing x-rays

Category: Ankle Arthritis; Ankle Introduction/Purpose: Postoperative evaluation of the total ankle arthroplasty (TAA) alignment is a fundamental step in measuring the surgical outcome. The current reference standard, weight-bearing x-ray (WBXR), is subject to technical bias. Weight-bearing cone beam computer tomography (WBCT) allows visualization of the complex three-dimensional (3D) structure of the foot under the influence of its deforming forces. A WBCT-based measurement system to assess postoperative outcomes has yet to be validated. The purpose of this study was (1) to measure the surgical outcome of TAA using semiautomatic generated models, (2) to evaluate the agreement levels between two raters, and (3) to evaluate the inter-method reliability with respect to WBXR. Methods: Fifty-five consecutive patients were retrospectively viewed. Two raters independently created a 3D model using dedicated software. Each rater measured six different measurements: α angle tibiotalar angle, hind foot angle (HFA), β angle, γ angle, and Φ angle using a semiautomatic 3D model and one measurement, the tibiatalar ratio (TTR) using WBCT on sagittal view. Measurements were repeated two months apart in the same independent fashion. Results were compared to standard weight- bearing x-rays. Consequently, interobserver, intraobserver, and intermethod agreements were calculated. Results: All seven measurements showed good to excellent interobserver and interobserver reliability. (ICC 0.85-0.95). The intermethod agreement showed good agreement for the γ angle (0.79) moderate agreement levels for the α angle, TTS angle, β angle, and TTR (ICC 0.68, 0.69, 0.70, 0.69 respectively), a poor agreement for the HFA angle (ICC 0.25), and a negative agreement for the φ angle (ICC -0.2). Conclusion: Postoperative analysis of TAA using WBCT demonstrated good to excellent interobserver and intraobserver agreement and can be reliably used. When compared to WBXR, moderate to good agreement was measured for the sagittal and coronal alignment of the components. A poor agreement was measured for the coronal alignment of the hindfoot, and a negative agreement was measured for the axial rotation angle, indicating that the intermethod comparison is unreliable.

PDB-BRE: A ligand-protein interaction binding residue extractor based on Protein Data Bank.

Proteins typically exert their biological functions by interacting with other biomolecules or ligands. The study of ligand-protein interactions is crucial in elucidating the biological mechanisms of proteins. Most existing studies have focused on analyzing ligand-protein interactions, and they ignore the additional situational of inserted and modified residues. Besides, the resources often support only a single ligand type and cannot obtain satisfied results in analyzing novel complexes. Therefore, it is important to develop a general analytical tool to extract the binding residues of ligand-protein interactions in complexes fully. In this study, we propose a ligand-protein interaction binding residue extractor (PDB-BRE), which can be used to automatically extract interacting ligand or protein-binding residues from complex three-dimensional (3D) structures based on the RCSB Protein Data Bank (RCSB PDB). PDB-BRE offers a notable advantage in its comprehensive support for analyzing six distinct types of ligands, including proteins, peptides, DNA, RNA, mixed DNA and RNA entities, and non-polymeric entities. Moreover, it takes into account the consideration of inserted and modified residues within complexes. Compared to other state-of-the-art methods, PDB-BRE is more suitable for massively parallel batch analysis, and can be directly applied for downstream tasks, such as predicting binding residues of novel complexes. PDB-BRE is freely available at http://bliulab.net/PDB-BRE.

Imaging of excised cochleae by micro-CT: staining, liquid embedding, and image modalities.

Assessing the complex three-dimensional (3D) structure of the cochlea is crucial to understanding the fundamental aspects of signal transduction in the inner ear and is a prerequisite for the development of novel cochlear implants. X-ray phase-contrast computed tomography offers destruction-free 3D imaging with little sample preparation, thus preserving the delicate structure of the cochlea. The use of heavy metal stains enables higher contrast and resolution and facilitates segmentation of the cochlea. For μ-CT of small animal and human cochlea, we explore the heavy metal osmium tetroxide (OTO) as a radiocontrast agent and delineate laboratory from synchrotron CT. We investigate how phase retrieval can be used to improve the image quality of the reconstructions, both for stained and unstained specimens. Image contrast for soft tissue in an aqueous solution is insufficient under the in-house conditions, whereas the OTO stain increases contrast for lipid-rich tissue components, such as the myelin sheaths in nervous tissue, enabling contrast-based rendering of the different components of the auditory nervous system. The overall morphology of the cochlea with the three scalae and membranes is very well represented. Further, the image quality of the reconstructions improves significantly when a phase retrieval scheme is used, which is also suitable for non-ideal laboratory settings. With highly brilliant synchrotron radiation (SR), we achieve high contrast for unstained whole cochleae at the cellular level. The OTO stain is suitable for 3D imaging of small animal and human cochlea with laboratory , and relevant pathologies, such as a loss of sensory cells and neurons, can be visualized. With SR and optimized phase retrieval, the cellular level can be reached even for unstained samples in aqueous solution, as demonstrated by the high visibility of single hair cells and spiral ganglion neurons.

Chromatin remodeling analysis reveals the RdDM pathway responds to low-phosphorus stress in maize.

Chromatin in eukaryotes folds into a complex three-dimensional (3D) structure that is essential for controlling gene expression and cellular function and is dynamically regulated in biological processes. Studies on plant phosphorus signaling have concentrated on single genes and gene interactions. It is critical to expand the existing signaling pathway in terms of its 3D structure. In this study, low-Pi treatment led to greater chromatin volume. Furthermore, low-Pi stress increased the insulation score and the number of TAD-like domains, but the effects on the A/B compartment were not obvious. The methylation levels of target sites (hereafter as RdDM levels) peaked at specific TAD-like boundaries, whereas RdDM peak levels at conserved TAD-like boundaries shifted and decreased sharply. The distribution pattern of RdDM sites originating from the Helitron transposons matched that of genome-wide RdDM sites near TAD-like boundaries. RdDM pathway genes were upregulated in the middle or early stages and downregulated in the later stages under low-Pi conditions. The RdDM pathway mutant ddm1a showed increased tolerance to low-Pi stress, with shortened and thickened roots contributing to higher Pi uptake from the shallow soil layer. ChIP-seq results revealed that ZmDDM1A could bind to Pi- and root development-related genes. Strong associations were found between interacting genes in significantly different chromatin-interaction regions and root traits. These findings not only expand the mechanisms by which plants respond to low-Pi stress through the RdDM pathway but also offer a crucial framework for the analysis of biological issues using 3D genomics.

Effects of landscape on thermal livability at the community scale based on fine-grained geographic information: A case study of Shenzhen

In the current research, the question of how to modify the microclimate through landscape planning to create a livable thermal environment within a residential community area has not been clarified. Therefore, this study investigated the effects of landscape on thermal livability in 2980 communities in Shenzhen, and obtained the following findings: (1) the proportion of trees and the average building height were key indicators to determine the average land surface temperature (LST) of a community, while the two-dimensional building characteristics, particularly shape, similarity, and patch dominance, were mainly responsible for regulating the spatial distribution of LST within a community; (2) at the community scale, the cooling intensity of buildings was strongest when their average height was around 40-60 m, and cooling effect of trees was most pronounced when their proportion achieved 20 %; and (3) the LST threshold for thermal livability in Shenzhen was around 35 °C. In summer, a higher proportion of trees and grass, as well as buildings with higher average heights, larger volume ratios, and more complex three-dimensional structures were favorable to maintain a livable community thermal environment, while in winter, a lower proportion of trees was more encouraged. In addition, a smaller average sky view factor can achieve a community thermal environment that warm in winter and cool in summer. These results are expected to facilitate urban planners to develop community renewal from the perspective of thermal livability.

Innovative Imaging Techniques: A Conceptual Exploration of Multi-Modal Raman Light Sheet Microscopy.

Advances in imaging of microscopic structures are supported and complemented by adaptive visualization tools. These tools enable researchers to precisely capture and analyze complex three-dimensional structures of different kinds such as crystals, microchannels and electronic or biological material. In this contribution, we focus on 3D cell cultures. The new possibilities can play a particularly important role in biomedical research, especially here in the study of 3D cell cultures such as spheroids in the field of histology. By applying advanced imaging techniques, detailed information about the spatial arrangement and interactions between cells can be obtained. These insights help to gain a better understanding of cellular organization and function and have potential implications for the development of new therapies and drugs. In this context, this study presents a multi-modal light sheet microscope designed for the detection of elastic and inelastic light scattering, particularly Rayleigh scattering as well as the Stokes Raman effect and fluorescence for imaging purposes. By combining multiple modalities and stitching their individual results, three-dimensional objects are created combining complementary information for greater insight into spatial and molecular information. The individual components of the microscope are specifically selected to this end. Both Rayleigh and Stokes Raman scattering are inherent molecule properties and accordingly facilitate marker-free imaging. Consequently, altering influences on the sample by external factors are minimized. Furthermore, this article will give an outlook on possible future applications of the prototype microscope.

Control of Cowl Shock/Boundary Layer Interaction in Supersonic Inlet Based on Dynamic Vortex Generator

A shock wave/boundary layer interaction (SWBLI) is a common phenomenon in supersonic inlet flow, which can significantly degrade the aerodynamic performance of the inlet by inducing boundary layer separation. To address this issue, in this paper, we propose the use of a dynamic vortex generator to control the SWBLI in a typical supersonic inlet. The unsteady simulation method based on dynamic grid technology was employed to verify the effectiveness of the proposed method of control and investigate its mechanism. The results showed that, in a duct of finite width at the inlet, the SWBLI generated complex three-dimensional (3D) flow structures with remarkable swirling properties. At the same time, vortex pairs were generated close to the side wall as a result of its presence, and this led to the intensification of transverse flow and, in turn, the formation of a complex 3D structure of the flow of the separation bubble. The dynamic vortex generator induced oscillations of variable intensity in the vortex system in the supersonic boundary layer that enhanced the mixing between the boundary layer flow and the mainstream. Meanwhile, the unique effects of “extrusion” and “suction” in the oscillation process continued to charge the airflow, and the distribution of velocity in the boundary layer significantly improved. As the oscillation frequency of the vortex generator increased, its charging effect on low-velocity flow in the boundary layer increased, and its control effect on the flow field of the SWBLI became more pronounced. The proposed method of control reduced the length of the separation bubble by 31.76% and increased the total pressure recovery coefficient at the inlet by 6.4% compared to the values in the absence of control.

Detailed mapping of below canopy surface temperatures in forests reveals new perspectives on microclimatic processes

The microclimate within forest stands might change rapidly in space and time due to the complex three-dimensional structure of forests. We are nowadays able to map the structure of forest stands in high detail, due to advances in Light Detection and Ranging (LiDAR) technologies such as terrestrial laser scanning (TLS). But measurements of microclimatic properties are often still bound to sensors which are only able to provide point measurements. Therefore, we propose a novel method to map the surface temperatures of a mature forest stand based on sensor fusion of TLS and thermal imaging as a time series. We provide insights into small scale temperature changes like sun flecks, or different bark structures. The results were also indicative of a cooling effect on tree trunks due to the uptake of cooler soil water, which is directly linked to the sap flux within the tree. While being only a first proof of concept of this method, our study provides a successful characterisation of spatio-temporal dynamics in trunk temperatures and indicates a potential promising correlation with ecohydrological processes. Our results suggest this novel technology to open various opportunities for future research and ecosystem monitoring.

Electrospun Membrane Fabrication in Assisting Tissues Healing

The arrangement of fibers into three-dimensional (3D) complex structure is constructing a sheet of membrane, depending on the fabrication technique. The fiber mats and scaffolds have been used in various applications including tissue engineering which involve the integration of cells and tissues within the pores between the fibers. There are several techniques that have been opted to produce specifically nanofibers as its efficacy in tissue healing is prominent compared to microfibers. Among the fabrication techniques (drawing, template synthesis, temperature-induced phase separation, molecular self-assembly, and electrospinning), electrospinning method has drawn attention due to their easy handling, inexpensive, and ability for membrane scale-up with the production of fibers ranging from few nanometers to several microns. Researchers have employed a variety of electrospinning methods, including blended/co-electrospinning, emulsion, coaxial, side-by-side, and triaxial electrospinning. In electrospinning smooth formation of nanofibers for tissue healing with less appearance of spray and beads, several parameters such as humidity, temperature, voltage, flow rate, viscosity, concentration, molecular weight, surface tension, conductivity, and solvent volatile need to be tailored. The morphology of nanofibers formation should support the size and structure of the surrounded cells and tissues. Besides, the types of degradable polymeric materials also play a role in the formation of stable nanofibers. This review paper aimed to provide information on the techniques to produce nanofibers, intended to the basic exploration of electrospinning.

Controlled Self-Assembly of Gold Nanotetrahedra into Quasicrystals and Complex Periodic Supracrystals.

The self-assembly of shape-anisotropic nanocrystals into large-scale structures is a versatile and scalable approach to creating multifunctional materials. The tetrahedral geometry is ubiquitous in natural and manmade materials, yet regular tetrahedra present a formidable challenge in understanding their self-assembly behavior as they do not tile space. Here, we report diverse supracrystals from gold nanotetrahedra including the quasicrystal (QC) and the dimer packing predicted more than a decade ago and hitherto unknown phases. We solve the complex three-dimensional (3D) structure of the QC by a combination of electron microscopy, tomography, and synchrotron X-ray scattering. Nanotetrahedron vertex sharpness, surface ligands, and assembly conditions work in concert to regulate supracrystal structure. We also discover that the surface curvature of supracrystals can induce structural changes of the QC tiling and eventually, for small supracrystals with high curvature, stabilize a hexagonal approximant. Our findings bridge the gap between computational design and experimental realization of soft matter assemblies and demonstrate the importance of accurate control over nanocrystal attributes and the assembly conditions to realize increasingly complex nanopolyhedron supracrystals.

On the attitude stability of flying dandelion seeds

Dandelion seeds possess a complex three-dimensional structure and a self-adapted flying ability. To understand this fascinating flight mechanism, a three-dimensional umbrella-shaped model imitating dandelion seeds is proposed. The effects of folding angle and flow velocity on the dandelion drag force during their descent are studied, and it is found that the larger folding angle results in a smaller drag coefficient. Four different vortex structures are revealed depending on the folding angle. The effect of crosswind disturbances on the attitude stability of dandelions is also investigated by changing folding angles. It is found that dandelions with larger folding angles have better attitude stability. The proposed model suggests that when the folding angle is between 20° and 40°, the dandelion seeds might have a good balance between the drag force and attitude stability, which ensures a broad self-adapted flying ability.

Analysis of the Complex Three-Dimensional Flow Structure in the Circulation Pump of the Flow-Making System Based on Delayed Detached Eddy Simulation

As the core component of the flow-making system, the circulating pump has differences in its internal flow structure under different operating conditions, which affects the flow quality of the environmental simulation test area and the authenticity of marine environmental simulation. To explore the internal flow characteristics and outlet evolution characteristics of the circulating pump, this paper uses the DDES (delayed detached eddy simulation) method for numerical simulation. This paper combines BVF (boundary vorticity flow) diagnosis and the limit streamline method to analyze the evolution characteristics of the unstable flow area on the blade surface; it uses the Q criterion to identify the vortex structure inside the pump and analyze its evolution and development laws. Additionally, a quantitative analysis of the flow state of the circulating pump using flow uniformity indexes is performed. The results show that the surface of impeller blades is uniform under 1.0 QN. At 0.7 QN, the evolution process of the blade suction surface BVF is periodic, with a corresponding period of about 2/9 T (0.02 s). At 1.0 QN, the strength and scale of the separated vortices inside the guide vanes are minimized compared to other flow rates, and the scale and strength of the vortices show a decreasing trend along the outer normal direction. The evolution period of the separation vortex on the pressure surface of the guide vane is about 1/3 T (0.033 s) under 1.1 QN and the evolution period of the suction surface of the guide vane is about 2/3 T (0.067 s) under 0.7 QN. The flow uniformity indexes value downstream of the pump outlet under 1.0 QN are very close to the ideal value; with a corresponding value of Ϛi = 0.023, θ¯ = 89.94°, γ = 0.95, λ = 97.9%, the outflow can be approximately regarded as axial uniform flow. The research results can provide theoretical support for the further optimization design of circulating pumps and lay the foundation for the implementation of real systems.

Production and mechanical characterization of Titanium Carbide ISOL target disks fabricated by direct ink writing

Titanium carbide boasts a large variety of high-temperature applications from aerospace to electronics and is also employed as Isotope Separation On-Line target for the production of Radioactive Ion Beams, which are employed in numerous research and technological fields, ranging from nuclear physics to medical applications. High working temperature, open and tailored porosity and resistance to thermal stresses are fundamental characteristics for this kind of targets. In this work, an extrusion-based additive manufacturing technique (Direct Ink Writing) was used for the fabrication of complex three-dimensional macro-porous structures in the shape of disks with dimensions compatible for their use as targets. An ink containing a suspension of TiC powders with solid loading of 47.5 vol% was prepared and its rheological properties were investigated. Afterwards, single filaments with an average diameter of 0.36 mm were produced and characterized with four-point bending tests to determine the bulk material tensile strength and Young's modulus. TiC targets were then manufactured and their mechanical properties were characterized with the Ball on Three Balls approach, a biaxial flexural test suitable for disk-shaped samples. For both flexural tests, a Finite Element model was developed representatively reproducing the experimental results. The calculated tensile strength values for both filaments and disks were analyzed with Weibull's statistical approach to provide reference stress limit, corresponding to a survival probability of 99.9%.

Anionic Templates Drive Conversion between a ZnII9L6 Tricapped Trigonal Prism and ZnII6L4 Pseudo-Octahedra.

This work introduces the use of 8-aminoquinoline subcomponents to generate complex three-dimensional structures. Together with a tris(formylpyridine), 8-aminoquinoline condensed around ZnII templates to produce a tris(tridentate) ligand. This ligand is incorporated into either a tricapped trigonal prismatic ZnII9L6 structure or a pair of pseudo-octahedral ZnII6L4 diastereomers, with S4 and D2 symmetries. Introduction of a methyl group onto the aminoquinoline modulated the coordination sphere of ZnII, which favored the ZnII9L6 structure and disfavored the ZnII6L4 assembly. The tricapped trigonal prismatic ZnII9L6 architecture converted into a single ZnII6L4 cage diastereomer following the addition of a dianionic 4,4'-dinitrostilbene-2,2'-disulfonate guest. Four of these guests clustered tightly at the four windows of the ZnII6L4 cage, held in place through electrostatic interactions and hydrogen bonding, stabilize a single diastereomeric configuration with S4 symmetry.