Characterization Of Physical Properties Research Articles

Terahertz frequency-domain sensing combined with quantitative multivariate analysis for pharmaceutical tablet inspection

Near infrared (NIR) and Raman spectroscopy combined with multivariate analysis are established techniques for the identification and quantification of chemical properties of pharmaceutical tablets like the concentration of active pharmaceutical ingredients (API). However, these techniques suffer from a high sensitivity to particle size variations and are not ideal for the characterization of physical properties of tablets such as tablet density. In this work, we have explored the feasibility of terahertz frequency-domain spectroscopy, with the advantage of low scattering effects, combined with multivariate analysis to quantify API concentration and tablet density. We studied 33 tablets, consisting of Ibuprofen, Mannitol, and a lubricant with API concentration and filler particle size as the design factors. The terahertz signal was measured in transmission mode across the frequency range 750 GHz to 1.5 THz using a vector network analyzer, frequency extenders, horn antennas, and four off-axis parabolic mirrors. The attenuation spectral data were pre-processed and orthogonal partial least square (OPLS) regression was applied to the spectral data to obtain quantitative prediction models for API concentration and tablet density. The performance of the models was assessed using test sets. While a fair model was obtained for API concentration, a high-quality model was demonstrated for tablet density. The coefficient of determination (R2) for the calibration set was 0.97 for tablet density and 0.98 for API concentration, while the relative prediction errors for the test set were 0.7% and 6% for tablet density and API concentration models, respectively. In conclusion, terahertz spectroscopy demonstrated to be a complementary technique to Raman and NIR spectroscopy, which enables the characterization of physical properties of tablets like tablet density, and the characterization of API concentration with the advantage of low scattering effects.

Dough Rheological Properties and Characteristics of Wheat Bread with the Addition of Lyophilized Kale (Brassica oleracea L. var. sabellica) Powder

In this study, the effect of replacing 5 or 10% of wheat flour with lyophilized kale (Brassica oleracea L. var. sabellica) on the rheology of dough and bread characteristics (physical and textural properties, sensory acceptability, staling tendency) was evaluated. The farinographic analysis showed an increase in the development time, index of tolerance to mixing, and water absorption. The share of lyophilized kale in the dough affected changes in its rheological properties, e.g., increased the values of storage and loss moduli with a decrease in the value of the phase shift angle (tan δ) from 0.36 to 0.31 at 1 rad/s. A significant decrease in the values of instantaneous and viscoelastic compliance was also observed, and an increase in the value of zero shear viscosity. The incorporation of lyophilized kale into the dough caused a noticeable decrease in bread volume by about 10%, and porosity, by about 8%, despite the lack of statistical significance. Statistically significant changes were found in pore size and the presence of large pores > 5 mm2 in the crumb, while pores density increased. The enrichment of bread with lyophilized kale influenced a decrease in the brightness of the crumb from 73.7 to 49.5 while increasing the proportion of yellow and green color as a result of a considerable increase in the content of chlorophyll pigments and carotenoids. Bread enriched with lyophilized kale had lower acceptability than the control bread. The enrichment of the bread with powdered kale also caused changes in the texture of the crumb, e.g., the hardness on the first day of the study was 2.14 N in the control bread, while in the bread with 10% kale content it was 6.46 N. In addition, the enriched bread showed a decrease in springiness, cohesiveness, and resilience.

Unveiling the selenium content effect on the properties of TiSe2±α

We systematically examined the properties of the polycrystalline 1T-TiSe2±α series synthesized by solid-state method, combined chemical analysis and physical property characterization, including Energy-dispersive X-ray spectroscopy (EDXS), x-ray photoelectron spectroscopy (XPS) x-ray diffraction (XRD), resistivity, hall effect and magnetization measurement have been employed to study how Ti/Se ratio influences the charge density wave (CDW) formation, the crystal structure, and the electrical characteristics. The electrical resistivity of Se-rich -TiSe2 (Ti/Se ​= ​0.484) is found to be a metallic behavior with decreased CDW transition temperature. This study emphasizes how sensitive 1T-TiSe2 characteristics are to defects and stoichiometry.

A Novel Protection Method for Carbonate Stone Artifacts with Gypsum Weathering Crusts

An innovative method using a methanol solution of barium hydroxide-urea as a protective agent was investigated for the conservation of stone artifacts with harmful gypsum weathering crusts. In this method, the methanol solution of barium hydroxide-urea and water were introduced into the gypsum crust in sequence by surface spraying. By doing so, the harmful gypsum crust is directly converted into a barium sulfate—calcium carbonate composite protective layer. The properties of the composite layer were characterized by SEM-EDX, XRD, ATR-FTIR, IC, water solubility, wetting angle, color difference, open porosity, capillary water absorption, and surface hardness. The results of the morphological and composition characterization (SEM-EDX, XRD, ATR-FTIR) indicate that the added urea can promote the carbonization reaction effectively. In addition, the methanol solution of barium hydroxide-urea can penetrate deep into the gypsum crust. The results of the physical properties characterization denote that the water stability of the specimens was significantly increased after the protection treatment; an approximate ten-fold stronger water resistance ability was achieved. Meanwhile, the intrinsic physical properties of gypsum crust, such as pore structure and original appearance, could basically be maintained. The presented conservative method has high facility and controllability and satisfying conservation effect, which means it has potential in the conservation of surface weathering carbonate stone artifacts.

Facile synthesis of Ag nanoparticles-decorated WO3 nanorods and their application in O2 sensing

Here we describe a two-step aerosol-assisted chemical vapor deposition (AACVD) synthesis method for the fabrication of Ag nanoparticles (NPs) decorated WO3 nanorods (NRs), evaluating the use of different organometallic silver precursors. Physical property characterization techniques including XRD, SEM, TEM, and XPS were carried out to investigate the composition and morphology of the pristine WO3 NRs and functionalized WO3 NRs with Ag NPs. The results showed that uniform WO3 NRs were obtained with a length of 600 nm to several μm and a diameter of 100–200 nm, and Ag NPs were well-dispersed on the surface of WO3 NRs with the size of 6–20 nm. The nanostructured WO3 thin films were synthesized and integrated directly onto alumina platforms via the AACVD method to fabricate gas sensors. Gas sensing performance was investigated towards different O2 concentrations between 1% and 20% at various operating temperatures. The sensing response revealed that an increase in baseline resistance was observed for the Ag-decorated WO3 sensors fabricated by using organometallic silver precursors, and the decoration of Ag NPs on WO3 sensors improved sensing properties as compared to the undecorated ones. The possible formation process and sensing mechanism of the Ag NPs decorated WO3 NRs are proposed.

Inference of mechanical properties and structural grades of bamboo by machine learning methods

• Characterization of physical and mechanical properties of Guadua angustifolia Kunth (GAK) was conducted. • Pooling of the datasets were performed to undertake a statistical analysis using machine learning (ML) methods. • Regression for mechanical properties were determined based on ML methods based on geometrical and physical properties. • Classification ML methods were used to propose a grading for structural bamboo species such as GAK. Features such as fast–growth rate, high strength–to–weight ratio, high carbon sequestering capability amongst others, make bamboo an excellent alternative environmental–friendly construction material. Therefore, it is very important to establish the most appropriate geometrical and/or physical properties that can be used to infer capacities as well as structural grades for bamboo such as Guadua angustifolia Kunth (GAK). Thus, an extensive experimental characterization of physical and mechanical properties of GAK was conducted by two independent laboratories –with samples from the same plantation in Colombia. Pooling of the two datasets were performed in order to create a larger data and undertake a more rigorous statistical analysis using machine learning (ML) methods. In addition, regression equations of mean and characteristic values for parallel–to–fiber compression, shear and bending capacities, and flexural stiffness were determined based on ML methods employing geometrical and physical properties. Finally, ML methods were used to propose a classification method based on four capacity classes that could enable a simpler grading process for structural bamboo species such as GAK.

KARAKTERISASI SIFAT FISIK DAN AKTIVITAS ANTIOKSIDAN PADA TEPUNG BUAH PEDADA (Sonneratia caseolaris) DENGAN SUHU PENGERINGAN BERBEDA

Pedada fruit (Sonneratia caseolaris) is a commodity of the fisheries and marine sectors that is able to prevent abrasion and as a place to live for several marine biotas. The part of the pedada fruit can be used starting from the leaves, stems, skin, and fruit. The advantages obtained are that the fruit can be directly eaten and has a variety of nutritional content of vitamins and secondary metabolites. Pedada fruit flour is able to become the substitution for flour that has high nutritional value. The role of drying temperature can improve physical and chemical properties, as well as increase the nutritional content and secondary metabolites that affect the quality of products. The research aimed to find out the physical characterization and antioxidant activity of pedada fruit flour (Sonneratia caseolaris) with different drying temperatures. This research method used the different drying temperatures of 40oC (R1), 50oC (R2), and 60oC (R3) with three repetitions. The main parameters are the characterization of physical properties which include yield tests, Particle Size Index (PSI), colour, and antioxidant activity. The supporting parameters were proximate analyses. Data analysis used Analysis of Variance (ANOVA) 1 factor and Least Significant Difference (LSD). The results showed that the physical characteristics of pedada fruit flour produced yields ranging from 8.38±0.08 to 11.31±0.10 with a Particle Size Index (PSI) above 96% in all treatments and the best colour appearance was light olive-brown at 40oC temperature. The value of antioxidant activity varies between 15.49±0.03 to 71.63±0.01 which decreases with increasing drying temperature and has a proximate analysis that is suitable for use as a substitute for consumption according to SNI. The effect of drying temperature on pedada fruit flour (Sonneratia caseolaris) had a significant effect (p<0.05) on physical characteristics, antioxidant activity, and proximate analysis.

Characterization and Optimization of Polymeric Bispicolamine Chelating Resin: Performance Evaluation via RSM Using Copper in Acid Liquors as a Model Substrate through Ion Exchange Method.

Advanced technologies of electronics industries have led to environmental contamination concerns, especially waste print circuit boards containing a very high concentration of copper (II) ions, which can be discharged in wastewater containing many contaminated metals. A low pH is a necessity for treating industrial wastewater containing heavy metals to meet engineering process design. A novel polymeric bispicolamine chelating resin, Dowex-M4195, was applied as an alternative for investigating the behavior of copper (II) in acidic solution via an ion exchange method in a batch experiment system. Characterization of physical and chemical properties before and after ion exchange were also explored through BET, SEM-EDX, FTIR and XRD. Response surface methodology was also applied for optimization of copper (II) removal capacity using design of experiment for selective chelating resin at a low pH. The results indicate that H+ Dowex-M4195 chelating resin had a high-carbon content and specific surface area of >64% and 26.5060 m2/g, respectively. It was predominantly macropore porous in nature due to the N2 gas adsorption isotherm and exhibited type IV with insignificant desorption hysteresis loop of H1-type. It was spherical and cylindrical. After the ion exchange process of copper (II)-loaded H+ Dowex-M4195, the specific surface area and total pore volume decreased by about 17.82% and 5.39%, respectively, as compared to H+ Dowex-M4195. Hysteresis loop, isotherm and pore size distribution were also similar. Regarding the functional group, the surface morphology and crystalline structures of H+ Dowex-M4195 showed copper (II) compound based on the structure of chelating resin that confirmed effective ion exchange behavior. The design of optimization indicated that copper (II) removal capacity of about 31.33 mg/g was achieved, which could be obtained at 6.96 h, pH of 2 (a desirable low pH), dose of 124.13 mg and concentration of 525.15 mg/L. The study indicated that the H+ Dowex-M4195 (which is commercially available on the market) can successfully be applied as an alternative precursor through the ion exchange method for further reuse and regeneration of the copper (II) in the electronic waste industries and other wastewater applications needed to respond the policy of biocircular green economy in Thailand.

Modeling of the Phase Inversion Point of Crude Oil Emulsion by Characterization of Crude Oil Physical Properties.

Accurate prediction of the phase inversion point (PIP) of crude oil emulsion (COE) will give important guiding significance to the mixed transportation technology during the crude oil mining process. The influence of water cut of a system on viscosity characteristics of the COE was studied by emulsification experiments with 16 kinds of crude oils having significant differences in physical properties. The results showed that under the condition of low water cut of a system, the crude oils can emulsify all the water to form stable W/O emulsions with apparent viscosities much higher than those of pure crude oils. When the water cut of a system exceeds a certain critical value, the crude oils have no ability to emulsify all water; instead, they are wrapped by a water phase and form unstable O/W emulsions, and their apparent viscosities decrease sharply compared with those of pure crude oils. The critical water cut of a system corresponding to the abrupt change of apparent viscosity of the COE is the PIP of the COE changing from the type of W/O to O/W. Furthermore, the apparent viscosities of stable W/O emulsions decrease with increasing shear rate and temperature and meanwhile increase dramatically with the increasing water cut of a system. The apparent viscosities of unstable O/W emulsions decrease with increasing shear rate, water cut of a system, and temperature and are far lower than those of pure crude oils. Four typical parameters were chose as the representation to describe the crude oil physical properties (COPPs), that is, the content of saturates, the content of aromatics, the content of surfactants, and the crude oil acid number. On the basis of the quantitative description of COPPs, a prediction model for the PIP of the COE was established. The results of model verification showed that the mean relative deviation of prediction results was 2.9%.

Characterization and Prediction of Physical Properties of Luanta Fir Wood with Vacuum Hydrothermal Treatment.

This study used the luanta fir (Cunninghamia konishii Hayata) wood, one of the most used wood construction and building materials in Taiwan, as specimens to examine the impact of different conditions of vacuum hydrothermal (VH) treatment on the physical properties of this wood. A prediction model for these properties was created using a nondestructive spectroscopy technique. The test results revealed that the mass loss, moisture exclusion efficiency, anti-swelling efficiency, color difference, and surface contact angle of the VH-treated wood all increased under increasing heat treatment temperature and time. Moreover, the use of near-infrared (NIR) spectroscopy in creating the prediction model for the physical properties of the VH-treated luanta fir wood revealed that the ratios of performance to deviation (RPD) for mass loss, equilibrium moisture content, and color difference were all above 2.5, indicating a high prediction accuracy. These results suggested that an NIR spectrometer can serve as a useful instrument for the accurate prediction of the physical properties or for controlling the quality of VH-treated wood.

Physical and Mechanical Properties of Paulownia tomentosa x elongata Sawn Wood from Spanish, Bulgarian and Serbian Plantations

The aim of this research is the characterization of physical and mechanical properties of Paulownia sawn wood from three plantation sites in Europe, namely Spain, Bulgaria and Serbia. As a fast-growing wood species, Paulownia has a significant positive forecast for the European markets and a wide range of possible applications that still need to be explored. For this purpose, Paulownia tomentosa(Tunb.) x elongata(S.Y. Hu) wood species was investigated. Sorption behaviour, Brinell hardness, 3-point bending strength, flexural modulus of elasticity, tensile strength, compressive strength and screw withdrawal resistance were examined in detail. The samples from Spain have the higher average bulk density (266 kg/m3), 3-point flexural strength (~40 N/mm2), 3-point flexural modulus of elasticity (~4900 N/mm2), compressive strength (~23 N/mm2), tensile strength (~44 N/mm2) and screw withdrawal resistance (~56 N/mm). The plantation wood from Bulgaria has the highest average of annual ring width (46 mm). Paulownia wood has potential in lightweight applications and can replace successfully expensive tropical species as Balsa.

Numerical and Experimental Investigations on the Ignition Behavior of OME

On the path towards climate-neutral future mobility, the usage of synthetic fuels derived from renewable power sources, so-called e-fuels, will be necessary. Oxygenated e-fuels, which contain oxygen in their chemical structure, not only have the potential to realize a climate-neutral powertrain, but also to burn more cleanly in terms of soot formation. Polyoxymethylene dimethyl ethers (PODE or OMEs) are a frequently discussed representative of such combustibles. However, to operate compression ignition engines with these fuels achieving maximum efficiency and minimum emissions, the physical-chemical behavior of OMEs needs to be understood and quantified. Especially the detailed characterization of physical and chemical properties of the spray is of utmost importance for the optimization of the injection and the mixture formation process. The presented work aimed to develop a comprehensive CFD model to specify the differences between OMEs and dodecane, which served as a reference diesel-like fuel, with regards to spray atomization, mixing and auto-ignition for single- and multi-injection patterns. The simulation results were validated against experimental data from a high-temperature and high-pressure combustion vessel. The sprays’ liquid and vapor phase penetration were measured with Mie-scattering and schlieren-imaging as well as diffuse back illumination and Rayleigh-scattering for both fuels. To characterize the ignition process and the flame propagation, measurements of the OH* chemiluminescence of the flame were carried out. Significant differences in the ignition behavior between OMEs and dodecane could be identified in both experiments and CFD simulations. Liquid penetration as well as flame lift-off length are shown to be consistently longer for OMEs. Zones of high reaction activity differ substantially for the two fuels: Along the spray center axis for OMEs and at the shear boundary layers of fuel and ambient air for dodecane. Additionally, the transient behavior of high temperature reactions for OME is predicted to be much faster.

Unraveling Nanoscale Elastic and Adhesive Properties at the Nanoparticle/Epoxy Interface Using Bimodal Atomic Force Microscopy.

The addition of a small fraction of solid nanoparticles to thermosetting polymers can substantially improve their fracture toughness, while maintaining various intrinsic thermomechanical properties. The underlying mechanism is largely related to the debonding process and subsequent formation of nanovoids at a nanoscale nanoparticle/epoxy interface, which is thought to be associated with a change in the structural and mechanical properties of the formed epoxy network at the interface compared with the matrix region. However, a direct characterization of the local physical properties at this nanoscale interface remains significantly challenging. Here, we employ a recently developed bimodal atomic force microscopy technique for the direct mapping of nanoscale elastic and adhesive responses of an amine-cured epoxy resin filled with ∼50 nm diameter silica nanoparticles. The obtained elastic modulus and dissipated energy maps with high spatial resolution evidence the existence of a ∼20-nm-thick interfacial epoxy layer surrounding the nanoparticles, which exhibits a reduced modulus and weaker adhesive response in comparison with the matrix properties. While the presence of such a soft and weak-adhesive interfacial layer is found not to affect the architecture of structural heterogeneities in the epoxy matrix, it conceivably supports the toughening mechanism related to the debonding and plastic nanovoid growth at the silica/epoxy interface. The incorporation of this soft interfacial layer into the Halpin-Tsai model also provides a good explanation for the effect of the silica fraction on the tensile modulus of cured epoxy nanocomposites.

Electrospinning of Biomedical Nanofibers/Nanomembranes: Effects of Process Parameters.

Nanotechnology has attracted great attention from researchers in modern science because nanomaterials have innovative and superior physical, chemical, and biological properties, and they can be altered and modified accordingly. As particles get smaller, their surface area increases compared to their volume. Electrospinning is one of the advanced techniques to produce ultrathin nanofibers and membranes, and it is one of the best ways to create continuous nanomaterials with variable biological, chemical, and physical properties. The produced fibers can be utilized in various domains such as wound dressing, drug release, enzyme immobilization, etc. This review examines the biomedical nanofibers/membranes produced by electrospinning techniques to investigate the effects of process parameters (e.g., solution characteristics, applied voltage, and ambient conditions) on nanofiber characteristics (physical, chemical, and mechanical properties). The solution parameters like (i) optimum concentration, (ii) higher molecular weight, and (iii) higher conductivity produce uniform nanofibers, smoother nanofibers, and a smaller and more uniform fiber diameter, respectively. In addition, process parameters such as (i) higher voltage and (ii) slower flow rate produce more polymer ejection from the nozzle and enhance the smoother fiber production, respectively. The optimum tip-to-collector distance is considered to be 13–15 cm. The ambient conditions such as (i) higher humidity and (ii) higher temperature produce thicker and thinner nanofibers, respectively. The controlled parameters through optimization process determine the size and quality of the fibers. The effects of each parameter are discussed in this review. The applications of nanofibers are also discussed.

Examination and Characterization of Physical and Mechanical Properties of the ITER Central Solenoid Module Coils

The ITER Central Solenoid (CS) consists of a stack of six independent coil packs called modules. It features a total height of 18 m and a diameter of over 4 m. The modules are in an advanced stage of fabrication and testing by the US ITER Project Office (USIPO) and its subcontractor General Atomics (GA). A qualification module mockup at one to one scale but of reduced height was wound and Vacuum Pressure Impregnated (VPI) by GA to validate final manufacturing, using tooling and processes fully representative of a series module. The module was submitted to a thermal cycle down to the temperature of 4.5 K at which the coils will be cooled by supercritical helium. During plasma operation, the CS modules are subjected to a complex combination of static and dynamic forces. The understanding of the mechanical behaviour of the CS module coils is of paramount importance to analyse and predict the overall response of the CS stack. To this purpose, an extensive programme of investigation of the module mockup has been defined and applied. This allowed assessing, through examination and testing of a large number of VPI conductor array samples extracted from the mockup, the soundness of the coil through advanced non-destructive examination techniques including X-ray microtomography, dimensional metrology measurements and micro-optical observations. Moreover, additional testing of physical and mechanical properties carried out at room and cryogenic temperature allowed the behaviour of the conductor stacks to be assessed. The paper summarises the results of these investigations and their interpretation through mechanical analyses based on the individual properties of the coil constituents.

Physical, barrier, and thermal properties characterization of edible films from composite mixtures of starch and starch derivatives

In the search for sustainable and ecological alternatives in food packaging, the use of starch as one of the most abundant biopolymer resources to formulate edible films has been studied. Nonetheless, compatibility with other starch derivatives, such as dextrin and/or chemically modified starch, has not been explored yet. The objective of this research was to characterize opacity, water vapor barrier capability, and thermal properties of composite edible films, by a mixture design approach, formulated with three types of commercial chemical modified starch mixed with native corn starch and dextrin. Lower opacity in edible films was related to more soluble material, where the main effect of dextrin was the rise of soluble material and lower water vapor permeability. A more permeable film can be obtained with Nifrastarch and lower permeability with Gelamil. The type of chemically modified starch used in edible films for edible packaging can be decided according to the characteristics of the food in question, i.e., moisture, color, permeability, or edible film solubility for active packaging.

History of ARIES: a premier research institute in the area of observational sciences

The Aryabhatta Research Institute of Observational Sciences (ARIES), a premier autonomous research institute under the Department of Science and Technology, Government of India has a legacy of about seven decades with contributions made in the field of observational sciences namely atmospheric and astrophysics. The Survey of India used a location at ARIES, determined with an accuracy of better than 10 m on a world datum through institute’s participation in a global network of Earth artificial satellites imaging during late 1950’s. Taking advantage of its high-altitude location, ARIES, for the first time, provided valuable input for climate change studies by long term characterization of physical and chemical properties of aerosols and trace gases in the central Himalayan regions. In astrophysical sciences, the institute has contributed precise and sometime unique observations of the celestial bodies leading to a number of discoveries. With the installation of the 3.6-m Devasthal optical telescope in the year 2015, India became the only Asian country to join those few nations of the world who are hosting 4-m class optical telescopes. This telescope, having advantage of geographical location, is well-suited for multi-wavelength observations and for sub-arc-second resolution imaging of the celestial objects including follow-up of the GMRT, AstroSat and gravitational-wave sources.

Disentangling the electronic structure of an adsorbed graphene nanoring by scanning tunneling microscopy

Graphene nanorings are promising model structures to realize persistent ring currents and Aharonov–Bohm effect at the single molecular level. To investigate such intriguing effects, precise molecular characterization is crucial. Here, we combine low-temperature scanning tunneling imaging and spectroscopy with CO functionalized tips and algorithmic data analysis to investigate the electronic structure of the molecular cycloarene C108 (graphene nanoring) adsorbed on a Au(111) surface. We demonstrate that CO functionalized tips enhance the visibility of molecular resonances, both in differential conductance spectra and in real-space topographic images. Comparing our experimental data with ab-initio density functional theory reveals a remarkably precise agreement of the molecular orbitals and enables us to disentangle close-lying molecular states only separated by 50 meV at an energy of 2 eV below the Fermi level. We propose this combination of techniques as a promising new route for a precise electronic characterization of complex molecules and other physical properties which have electronic resonances in the tip-sample junction.

Strain-Driven Mixed-Phase Domain Architectures and Topological Transitions in Pb1- x Srx TiO3 Thin Films.

The potential for creating hierarchical domain structures, or mixtures of energetically degenerate phases with distinct patterns that can be modified continually, in ferroelectric thin films offers a pathway to control their mesoscale structure beyond lattice-mismatch strain with a substrate. Here, it is demonstrated that varying the strontium content provides deterministic strain-driven control of hierarchical domain structures in Pb1- x Srx TiO3 solid-solution thin films wherein two types, c/a and a1 /a2 , of nanodomains can coexist. Combining phase-field simulations, epitaxial thin-film growth, detailed structural, domain, and physical-property characterization, it is observed that the system undergoes a gradual transformation (with increasing strontium content) from droplet-like a1 /a2 domains in a c/a domain matrix, to a connected-labyrinth geometry of c/a domains, to a disconnected labyrinth structure of the same, and, finally, to droplet-like c/a domains in an a1 /a2 domain matrix. A relationship between the different mixed-phase modulation patterns and its topological nature is established. Annealing the connected-labyrinth structure leads to domain coarsening forming distinctive regions of parallel c/a and a1 /a2 domain stripes, offering additional design flexibility. Finally, it is found that the connected-labyrinth domain patterns exhibit the highest dielectric permittivity.

Study on the High-Temperature Sintering Characteristics and Sintering Mechanism of Sea Sand Vanadium Titanomagnetite Based on Micro-sintering

The sea sand vanadium titanomagnetite has the problems of coarse particles, difficult agglomeration, and poor sintering performance. It is difficult for iron and steel enterprises to use it as an ironmaking raw material in large quantities. In this work, different methods were adopted to optimize the high-temperature sintering characteristics of sea sand vanadium titanomagnetite to increase the usage of sea sand ore. Based on the characterization and analysis of the basic physical and chemical properties of sea sand ore, the effects of adding limestone, ludwigite, and fine powder on the high-temperature sintering characteristics of sea sand ore were discussed. The proportion of sea sand ore was varied and its effect on the high-temperature sintering characteristics was studied. The phase composition and microstructure of sintered blocks with sea sand ore were analyzed by XRD and SEM–EDS, and the high-temperature sintering mechanism was studied. The results show that the high-temperature sintering characteristics of sea sand ore can be optimized to a certain extent by adding limestone, ludwigite, and fine powder. It is suggested that 15–35 wt% of sea sand ore was appropriate. The experimental results provided some reference methods for iron and steel enterprises to improve the utilization rate of sea sand ore in the actual sintering process.