Evolution Of Structural Properties Research Articles

Dielectric and structural properties evolution of PTFE-based high-frequency circuit substrates for mmwave application under hygrothermal aging

Dielectric and structural properties evolution of PTFE-based high-frequency circuit substrates for mmwave application under hygrothermal aging

Crystallization, structure-property evolution, and solidification of heavy metals of glass-ceramics based on copper tailing/coal slag/red mud

The Dexing copper tailing (DCT), Coal slag (CS) and Red mud (RM) were used to prepare a solid waste-derived glass-ceramics. The result shows that the stable base glass can be formed when DCT/CS/RM mass ration is 35/25/40. Different crystallization temperatures (780∼980 ℃) were implemented on the base glass, and found that the glass-ceramics with Ca(Mg0.5Al0.5)((Si1.5Al0.5)O6) as the main crystal phase can be synthesized, whose bulk density, water absorption, Vickers hardness, bending strength, acid/alkali-resistance are in the range of 2.747∼2.887 g/cm3, 0.010∼0.027 %, 6.65∼8.24 GPa, 33.89∼118.53 MPa, 67.77∼99.97/97.85∼99.98 %, respectively. Especially, the GC880 not only shows the best properties (bulk density: 2.87 g/cm3; water absorption: 0.018 %; Vickers hardness: 6.96 GPa; bending strength: 118.53 MPa; acid/alkali-resistance: 99.34/99.97 %), but also has an solidification effect on heavy metal ions (Cr3+/Mn2+/Fe3+/Cu2+/Ni2+), wherein the leaching concentration reduction rates of Mn2+ and Fe3+ are over 97 %, which has the potential to be applied in decorative glass-ceramics.

Morphological, structural and electronic properties of zinc oxide nano structures deposited on ZnO substrate layer – A theoretical perspective

The work investigates the deposition of zinc and oxygen atoms on a Zinc terminated ZnO substrate, maintaining their stoichiometric ratio (O:Zn) at 0.8, under varying incident energies (0.5 eV and 5 eV) and temperatures (300 K and 700 K) using the ReaxFF potential in Molecular Dynamics (MD) simulation. The study explores the impact of deposition conditions on growth mechanisms, film morphology, and structural parameters such as Radial Distribution Function (RDF) and Coordination Number (CN). RDF analysis highlights disordered atomic arrangements and diverse bonding configurations within the film, with CN showing deviations from perfect crystalline ZnO, indicating non-uniform, non-crystalline, and nano behaviour. Post-heating the films to temperatures approaching the ZnO melting point results in enhanced crystallinity, as evidenced by distinct, dominant, and multiple RDF peaks. Density Functional Theory (DFT) approach of the deposited structures elucidates the formation of ZnO nanoclusters-(ZnO)3 and (ZnO)4 and investigates their electronic structure properties. DFT analysis of the post-heated films reveals the formation of ZnO monomers (ZnO), indicating an approaching crystalline behaviour, yet the films exhibit non-epitaxial and non-uniform characteristics. DFT calculations were instrumental in validating the observed structural behaviours in the deposited films. The study underscores the significance of stoichiometric ratio in film deposition and demonstrates the temperature-dependent evolution of structural properties towards crystallinity, shedding light on the intricate dynamics of ZnO film growth offering tailored control over film properties for enhanced performance in practical applications such as optoelectronics and gas sensing.

Enabling tailored nanoporous germanium by quantifying the evolution of structural properties during self-irradiation

Porous materials are essential for a wide range of applications in energy storage, catalysis, and environmental solutions. Material fabrication methods which can tailor the porous structures in a deterministic manner are highly valuable for the development of the field. In this paper, we use ion irradiation to synthesize large-scale germanium (Ge)-based porous structures. We furthermore demonstrate the structure to consist of pores interconnected by ultra-small channels that effectively allow transport of gaseous molecules throughout the whole network. Aside qualitative assessment of the evolution of the structure, the combination of transmission electron microscopy, microbeam Rutherford backscattering spectrometry and a Ge-on-Si sample design enables the quantification of properties such as mass density and sputtering yields during the evolution of porosity. We find progression of pore formation from the surface with a constant rate with increasing dose at otherwise constant density of the porous phase. Proximity to the substrate terminates pore formation well before reaching the interface with higher doses, eventually inducing a depth-independent densification of the porous structure. Experimental evidence challenges vacancy clustering as a commonly referred-to mechanism for pore-formation. Instead, relaxation in structurally weakened, i.e. near-surface volumes of the material by micro-explosions can conclusively explain all observations. The porous germanium synthesized in our approach is considered more resilient at high temperature and strong pH conditions than polymeric and hybrid materials, indicating great potential for applications in such environments.

Evolution of structural properties of the global strategic emerging industries' trade network and its determinants: An TERGM analysis

This article examines the evolution of the global strategic emerging industries trade networks (GSEITNs) and employs the temporal exponential random graph model (TERGM) to investigate the principal determinants of the critical trade cooperation in the global strategic emerging industries (SEIs) from 2007 to 2020. The findings indicate that GSEITNs exhibit a sparse, hierarchical, and monopolistic structure. Despite the continual integration of emerging nations into GSEITNs, countries have grown progressively wary of the network. Moreover, the structure properties of the endogenous network proves that SEIs trade links have a substantial signaling effect. More importantly, SEIs trade is more reliant on the economic size and innovation capacity, and countries are more cautious about protecting their intellectual property, especially when trading with countries possessing similar R&D levels. Furthermore, robust bilateral political ties can augment the probability of SEIs trade between two countries, particularly in sectors such as new energy vehicles and new-generation information technology industries. In summary, this article takes into account the influence of network structure, national attributes and external networks, and provides new insights into studying trade network evolution in SEIs.

Structure–property evolution of poly(ethylene terephthalate)/poly(trimethylene terephthalate) side‐by‐side self‐crimp filament

AbstractTo investigate the microstructure and mechanical properties of self‐crimping two‐component side‐by‐side bicomponent filament, this paper focuses on systematically investigating the structure–property evolution of poly(ethylene terephthalate) (PET)/poly(trimethylene terephthalate) (PTT) side‐by‐side bicomponent filament prepared via melt spinning with various component ratios, drawing and heating treatment. The investigation was operated upon the combination of morphology analysis, thermal analysis, crystallization, and orientation analysis. The variation of cross section and curl‐morphology, crystallization, and microstructures mainly containing lamellar and microfibrillar crystals as well as their effects on the mechanical and self‐crimping properties were discussed. As the draft ratio (DR) increases, the crystallinity, sonic orientation factor, tensile strength, and crimp‐recovery rate of the filaments were increased. The sonic orientation factor in the crystalline region decreases from 0.923 to 0.777 but increases from 0.677 to 0.903 in the amorphous region. In contrast to the variation of the DR, heating temperature has a limited effect on the tensile strength of the PET/PTT hybrid filaments. Crimp‐recovery rate, however, first increases to 11.8 and then decreases to 9.8 with an increasing heating temperature from 144 to 168°C. Most of these behaviors have been attributed to changes in the ratio of contractile stress for both PTT and PET components, originating from microstructural evolution in hybrid filaments, including crystal growth, breakage, deflection, and deformation of chains along the axial direction. As a summary, an interpretive diagrammatic sketch has been proposed to clarify the structure–property relationships of the commercial PET/PTT filaments.

Ta interfaced CoFeB: Role of CoFeB thickness and thermal annealing in modification of structural and magnetic properties

CoFeB interfaced with heavy metals is a potential system for spintronic applications. In the present work, evolution of magnetic and structural properties of CoFeB interfaced with Ta have been studied as function of increasing thickness of magnetic film and increasing annealing temperature. While the evolution of structural properties was investigated using X-ray scattering measurements i.e., X-ray reflectivity (XRR) and grazing incidence X-ray Diffraction (GIXRD), the modification of magnetic properties were studied using vibrating sample magnetometer (VSM) and magneto-optical Kerr effect (MOKE) measurements. The detailed XRR analysis shows the diffusion of Boron to the bottom Ta layer with annealing, which increases significantly for post-crystallized phase. Such enriched B diffusion also increases the thickness of interfacial magnetic dead layer as confirmed from VSM results. The synchrotron XRD show an increased in-plane CoFe grain size relative to out-of-plane grain size, while CoFeB is interfaced with Ta. MOKE measurements confirm the presence of stress-induced uniaxial magnetic anisotropy in as-deposited CoFeB films, which reduces for Ta-interfaced CoFeB. Vacuum annealing well above the crystallization temperature eliminates such magnetic anisotropy with concurrent increase of magnetic coercivity (Hc) because of increasing grain size. CoFeB interfaced with Ta shows an abrupt enhancement of Hc, as compared to CoFeB without Ta interface.

Optical and structural investigations of annealing impact on phase separation of Erbium-doped Al2O3 layers

We report on the effect of annealing treatment on the structural and optical properties of Er-doped Al2O3 thin films elaborated by atomic layer deposition. The properties of the films were studied using ellipsometry and Fourier-transform infrared (FTIR) spectroscopies, cathodoluminescence (CL) versus annealing temperature varied in the 650-1100 °C range. Spatial location and diffusion of chemical species were investigated at the atomic scale by atom probe tomography (APT). The CL measurements evidence Er3+ light emission over the visible-infrared spectral range. The CL spectra evolution showed non-monotonic variation with annealing temperature and a CL quenching occurring at 1000 °C. The CL signal evolution as a function of the annealing treatment is discussed regarding to the evolution of structural properties.

Structural features of Li0.55Ag0.45InSe2 and Li0.37Ag0.63InSe2 crystals

Li0.55Ag0.45InSe2 crystals with orthorhombic structure were grown by the Bridgman-Stockbarger method with Li0.37Ag0.63InSe2 microcrystals of tetragonal modification found on their surface.The effect of substitution of silver and lithium ions on the evolution of structural properties in Li0.55Ag0.45InSe2 and Li0.37Ag0.63InSe2 phases was investigated. A fundamental difference in the change of unit cell parameters in the temperature range of 100–300 K has been revealed. A negative temperature expansion coefficient along the c axis was detected in the tetragonal modification Li0.37Ag0.63InSe2.

25 Years of Small-Molecule Optimization at Novartis: A Retrospective Analysis of Chemical Series Evolution.

In the drug development process, optimization of properties and biological activities of small molecules is an important task to obtain drug candidates with optimal efficacy when first applied in subsequent clinical studies. However, despite its importance, large-scale investigations of the optimization process in early drug discovery are lacking, likely due to the absence of historical records of different chemical series used in past projects. Here, we report a retrospective reconstruction of ∼3000 chemical series from the Novartis compound database, which allows us to characterize the general properties of chemical series as well as the time evolution of structural properties, ADMET properties, and target activities. Our data-driven approach allows us to substantiate common MedChem knowledge. We find that size, fraction of sp3-hybridized carbon atoms (Fsp3), and the density of stereocenters tend to increase during optimization, while the aromaticity of the compounds decreases. On the ADMET side, solubility tends to increase and permeability decreases, while safety-related properties tend to improve. Importantly, while ligand efficiency decreases due to molecular growth over time, target activities and lipophilic efficiency tend to improve. This emphasizes the heavy-atom count and log D as important parameters to monitor, especially as we further show that the decrease in permeability can be explained with the increase in molecular size. We highlight overlaps, shortcomings, and differences of the computationally reconstructed chemical series compared to the series used in recent internal drug discovery projects and investigate the relation to historical projects.

Evolution of Structural Properties in Fe Intercalated 2H-NbSe2: Phase Transformation Induced by Strong Host–Guest Interaction

Evolution of Structural Properties in Fe Intercalated 2H-NbSe₂: Phase Transformation Induced by Strong Host–Guest Interaction

Galaxy Evolution in All Five CANDELS Fields and IllustrisTNG: Morphological, Structural, and the Major Merger Evolution to z ∼ 3

Abstract A fundamental feature of galaxies is their structure, yet we are just now understanding the evolution of structural properties in quantitative ways. As such, we explore the quantitative nonparametric structural evolution of 16,778 galaxies up to z ∼ 3 in all five CANDELS fields, the largest collection of high-resolution images of distant galaxies to date. Our goal is to investigate how the structure, as opposed to size, surface brightness, or mass, changes with time. In particular, we investigate how the concentration and asymmetry of light evolve in the rest-frame optical. To interpret our galaxy structure measurements, we also run and analyze 250 simulation realizations from IllustrisTNG to determine the timescale of mergers for the CAS system. We measure that from z = 0–3, the median asymmetry merger timescale is 0.50 − 0.18 + 0.33 Gyr, and find that it does not vary with redshift. Using these data, we find that galaxies become progressively asymmetric at a given mass at higher redshifts, and we derive merger rates that scale as ∼ 1 + z 1.87 ± 0.04 Gyr−1, which agrees well with recent machine-learning and galaxy-pair approaches, removing previous inconsistencies. We also show that far-infrared selected galaxies that are invisible to the Hubble Space Telescope have a negligible effect on our measurements. We also find that galaxies are more concentrated at higher redshifts. We interpret this as a sign that their formation occurs from a smaller initial galaxy that later grows into a larger one through mergers, consistent with the size growth of galaxies from the inside out, suggesting that the centers are the oldest parts of most galaxies.

Evolution of structural properties and its determinants of global waste paper trade network based on temporal exponential random graph models

As an important recyclable and reusable resource, waste paper is traded in millions of dollars around the world every year. Global waste paper trade not only addresses resource scarcity issues, alleviates environmental pressures and brings substantial economic gains, but also contributes to the development of global circular economy. Using complex network methods, bilateral waste paper trade data, and temporal exponential random graph models (TERGM), we construct global waste paper trade networks (GWPTNs) during 2000–2018, and examine their structural evolution and determinants. We report that: (I) GWPTNs display obvious features of small-world network, low reciprocity, heterogeneity and disassortativity; (II) Asia is the leading recipient of global waste paper, while Europe and North America are the main exporters; (III) China and India dominate the waste paper import markets while the United States is the largest exporter, and Germany plays an essential role in both importing and exporting hubs of waste paper; (IV) The evolution of the GWPTNs is significantly influenced by endogenous reciprocity, transitivity and preferential attachment, and economies with more partners or within the same continents are more likely to trade waste paper. Economies with higher urbanization rates, more per capita income, stricter environmental regulation, or lower industrialization rates are more likely to export waste paper; conversely, they are more likely to be the importers. Economy-pairs sharing a language or religion, being a former colony of the same colonizer, historical colonial relationship or a border, or signing regional trade agreements are more likely to trade waste paper.

Structure and properties of gel‐spun ultra‐high molecular weight polyethylene fibers obtained from industrial production line

AbstractThe structure evolution of commercial fibers with excellent performance is always a hot research topic. In this work, we used samples obtained from different forming stages of industrial production lines with a total draw ratio of 54.5 to explore the structure–property evolution of ultra‐high molecular weight polyethylene (UHMWPE) fibers through a combination of differential scanning calorimetry, wide‐angle X‐ray diffraction, and small angle X‐ray scattering methods. The results showed that the preferential orientation of amorphous molecular chain and the crystallinity increased rapidly in predrawing process, but the mechanical properties were basically unchanged, demonstrating that this stage had little effect on mechanical properties of fibers. At first‐step drawing, the crystallinity and orientation degree increased from 68% to 81% and 0.88 to 0.97, respectively, accompanied by rapid increase in modulus and tensile strength (29.5 to 878.1 cN/dtex and 4.3 to 21.1 cN/dtex, respectively) and the formation of monoclinic phase and fibrillar crystals also happened at this stage. The content of monoclinic phase with tighter structure was increased during the second‐step and third‐step drawing, which were crucial for the continuous improving mechanical properties. In addition, the molecular schematic diagram was proposed to describe structural development of UHMWPE fibers during manufacture process.

Effects of working time on properties of a soybean meal-based adhesive for engineered wood flooring

ABSTRACT Soybean meal-based adhesives (SMAs) commercially applied in wood-based composites require stable bonding properties. However, the structure and properties of SMAs are not as stable as synthetic resins, which significantly affect their performances. In this study, the structure–property evolution of a SMA with working time was systematically investigated. The findings revealed that the secondary structure, microstructure, crosslinking density, zeta potential, nitrogen solubility index, viscosity, wood permeability, and bonding properties of SMA considerably vary with working time. The changes in adhesive properties were correlated with the dissolution of SM particles in crosslinker solution and the increased pre-curing of liquid SMA with working time resulting from the crosslinking reactions between the dissolved SM and the crosslinker. Preferably, SMA at the working time between 0.5 h and 3 h since the mixing of soybean meal flour with crosslinker solution, should be used in order to ensure the desired water resistance of plywood panels for engineered wood flooring. And an application strategy was proposed to ensure the required water resistance of plywood panels for manufacturing engineered wood flooring.

Neuronal circuits on a chip for biological network monitoring.

Cultured neuronal networks (CNNs) are a robust model to closely investigate neuronal circuits' formation and monitor their structural properties evolution. Typically, neurons are cultured in plastic plates or, more recently, in microfluidic platforms with potentially a wide variety of neuroscience applications. As a biological protocol, cell culture integration with a microfluidic system provides benefits such as accurate control of cell seeding area, culture medium renewal, or lower exposure to contamination. The objective of this report is to present a novel neuronal network on a chip device, including a chamber, fabricated from PDMS, vinyl and glass connected to a microfluidic platform to perfuse the continuous flow of culture medium. Network growth is compared in chips and traditional Petri dishes to validate the microfluidic chip performance. The network assessment is performed by computing relevant topological measures like the number of connected neurons, the clustering coefficient, and the shortest path between any pair of neurons throughout the culture's life. The results demonstrate that neuronal circuits on a chip have a more stable network structure and lifespan than developing in conventional settings, and therefore this setup is an advantageous alternative to current culture methods. This technology could lead to challenging applications such as batch drug testing of in vitro cell culture models. From the engineering perspective, a device's advantage is the chance to develop custom designs more efficiently than other microfluidic systems.

Correlation of luminescence measurements to the structural characterization of Pr3+-doped HfSiOx

Luminescence and structural properties of Pr3+ doped HfSiOx thin layer elaborated by magnetron sputtering have been investigated as a function of the annealing temperature. The emission properties of Pr3+ ions were studied using photoluminescence (PL) and cathodoluminescence (CL) spectroscopies. Phase separation between amorphous SiO2 and crystallized HfO2 nano-grains occurring in the HfSiOx matrix has been investigated by atom probe tomography and transmission electron microscopy with particular consideration for the Pr distribution. Both PL and CL measurements evidenced a strong emission originating from Pr3+ ions in the visible range for an annealing temperature higher than 950°C. At 950°C, Pr3+ ions are clearly located in HfO2 nano-grains of cubic structure. Regarding PL, no significant changes are observed between 950°C and 1050°C. However, CL measurements revealed new emission peaks in the infrared range after an annealing at 1050°C, corresponding to the appearance of a new orthorhombic crystalline structure of HfO2 nano-grains in the thin layer. The CL signal evolution as a function of the annealing treatment is discussed in regard to the evolution of structural properties.

Structural Characterization of Silk Fibers by Small-Angle X-Ray Scattering.

Nature is rich in all kinds of unbelievably designed microstructures, which endows the natural materials with various fantastic performances. Unveiling the mystery of the sophisticated configurations and the relationship between those microstructures and the corresponding functions is helpful for the manufacture of artificial functional materials. Small-angle X-ray scattering (SAXS) is an advanced tool to gain the microstructural features of materials within a spatial scale much larger than the atomic scale (1000nm), which can be carried out along with WAXS to conduct more systematic investigation over different kinds of materials. With the help of SAXS/WAXS, one may generate an insightful understanding of the mechanisms of structure-property evolution (which is efficient guidance for the artificial material designs). This chapter will introduce the mathematics and the methodologies used by SAXS when investigating the microstructure of natural materials.

Effects of low-dose γ-irradiation on the structural, morphological, and optical properties of fluorine-doped tin oxide thin films

This paper presents the effects of low-dose γ-irradiation on the structural, morphological, and optical properties of Fluorine-doped tin oxide (FTO) thin films for application as a passive thermal control coating in future miniaturized lightweight spacecraft. Commercial-grade FTO films on glass substrate (Pilkington Ltd, UK) with a bulk density of 2.5 g/cm3, sheet resistance of 12 Ω.sq-1, coating thickness of 450 nm, optical band-gap of 3.80 eV, a carrier concentration of 1.50×1020 cm−3 and a mobility of 15 cm2/Vs were irradiated at room temperature and atmospheric pressure using a 60Co gamma source (with gamma energies of 1.17 MeV and 1.33 MeV) at iThemba Laboratory for Accelerator Based Sciences, Cape Town, South Africa. Each sample was exposed to γ-rays for a different span of time to achieve a series of different integrated absorbed doses of 20, 30, and 50 Gy, at a dose rate of 0.207 Gy/min. Evolution in structural properties of the films was characterized using a Bruker AXS D8 Advance XRD with Cu-Kα (λ = 1.54056 Å) scanned in the 2θ degree range of 20 – 80 degrees. Surface properties were analyzed using a VEECO Dimension 1100 AFM machine. Meanwhile, variations in optical transmittance of the films was investigated using a Cary 5000 UV-vis-NIR spectrophotometer of Varian, Inc. model internal DRA- 2500 in the wavelength range of 200 – 2500 nm. XRD results indicate an enhancement of crystallization after irradiation, slight peak shifts, and variations in crystallite sizes with increasing dose. Surface roughness decreased with increasing dose and the grain structures also seen to vary with dose. No significant variations in optical transmittance of the FTO films.

RETRACTED: The evolution of structure properties of vegetation concrete under freeze–thaw cycles

Vegetation concrete is a typical artificial composite soil commonly used for ecological restoration on slopes. The strength and stability of vegetation concrete would be reduced when it is used in areas where freeze–thaw cycles occur frequently. For exploring the changes of structural properties of vegetation concrete under freeze–thaw cycles, an indoor simulation experiment of vegetation concrete samples containing 25 and 30% water content was carried out, so as to test the changes of specimen surface, volume, ultrasonic wave velocity, shearing strength, and microscopic structure. The microstructural parameters were analyzed quantitatively with Image-Pro Plus software. The experimental results indicated that as cycles of freeze–thaw grow, the macroscopic changes of samples included steadily rising surface crack rate, increasing first and then decreasing volume, greatly reducing ultrasonic wave velocity and gradually decreasing shear strength. The inner structure of samples slowly deteriorated from overall dense to dispersed with decreasing cement hydration crystals, pores resulting from dispersion and destruction of bulky grains, higher surface porosity, and smoother particles in microscopic aspect. When compared with samples containing 25% water content, the microstructure of the 30% water content sample was more affected by the freeze–thaw cycle, and its structural weakening effect was more obvious. Reduced cement hydration crystals, lower inter-particle bonding force, and increase in the number of large pores were the main causes of degradation of vegetation concrete structure. Electrical engineering students can refer to the analysis methods in this paper to evaluate the structural performance of any electrical engineering material.