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We report herein the synthesis of ZnFe2O4 (ZF) nanoparticles via a simple and eco-friendly green route using lemon juice as a reducing agent and fuel. The effect of different calcination temperatures on the particle size and bandgap of grown ZF nanoparticles was investigated. The structural, morphological and optical properties of the synthesized nanoparticles were evaluated using synchrotron x-ray diffraction (S-XRD), field emission scanning electron microscopy (FE-SEM) and UV-visible diffuse reflectance spectroscopy (UV-Vis-DRS), respectively. S-XRD confirmed a spinel F-d3m phase in all four samples calcined at 350°C, 550°C, 750°C and 1000°C. The crystallite size calculated from the Debye–Scherrer equation showed an increase from 14 nm to 20 nm with the increase in calcination temperature. Williamson–Hall (W-H) analysis revealed an increase in the particle size from 16 nm to 21 nm and a decrease in the lattice microstrain from 0.913 × 10−3 to 0.154 × 10−4 with the increase in calcination temperature. The optical bandgap of the ZF nanoparticles obtained from UV-Vis-DRS decreased from 2.265 eV to 2.225 eV with the increase in calcination temperature. The ZF nanoparticles with tunable particle size, lattice microstrain and optical bandgap have potential application in ferrofluid, electromagnetic shielding, photocatalysis, hyperthermia, dye degradation and other areas.

This paper gives an overview on some state-of-the-art characterization methods of SiO2/4H-SiC interfaces in metal oxide semiconductor field effect transistors (MOSFETs). In particular, the work compares the benefits and drawbacks of different techniques to assess the physical parameters describing the electronic properties and the current transport at the SiO2/SiC interfaces (interface states, channel mobility, trapping phenomena, etc.). First, the most common electrical characterization techniques of SiO2/SiC interfaces are presented (e.g., capacitance- and current-voltage techniques, transient capacitance, and current measurements). Then, examples of electrical characterizations at the nanoscale (by scanning probe microscopy techniques) are given, to get insights on the homogeneity of the SiO2/SiC interface and the local interfacial doping effects occurring upon annealing. The trapping effects occurring in SiO2/4H-SiC MOS systems are elucidated using advanced capacitance and current measurements as a function of time. In particular, these measurements give information on the density (~1011 cm−2) of near interface oxide traps (NIOTs) present inside the SiO2 layer and their position with respect to the interface with SiC (at about 1–2 nm). Finally, it will be shown that a comparison of the electrical data with advanced structural and chemical characterization methods makes it possible to ascribe the NIOTs to the presence of a sub-stoichiometric SiOx layer at the interface.

In this work, a 3D printed polymer–metal soft-magnetic composite was developed and characterized for its material, structural, and functional properties. The material comprises acrylonitrile butadiene styrene (ABS) as the polymer matrix, with up to 40 vol. % stainless steel micropowder as the filler. The composites were rheologically analyzed and 3D printed into tensile and flexural test specimens using a commercial desktop 3D printer. Mechanical characterization revealed a linearly decreasing trend of the ultimate tensile strength (UTS) and a sharp decrease in Young’s modulus with increasing filler content. Four-point bending analysis showed a decrease of up to 70% in the flexural strength of the composite and up to a two-factor increase in the secant modulus of elasticity. Magnetic hysteresis characterization revealed retentivities of up to 15.6 mT and coercive forces of up to 4.31 kA/m at an applied magnetic field of 485 kA/m. The composite shows promise as a material for the additive manufacturing of passive magnetic sensors and/or actuators.

This study aims to explore for the first time the thermoelastic buckling behavior of functionally graded porous plates and shells using an efficient finite element model based on the first-order shear deformation theory (FSDT) with the improvement of the shear strains via the introduction of a quadratic function that able to take into account the parabolic distribution of transverse shear stresses without any need of shear correction factors as standard (FSDT) theory. In this research, different sets of functionally graded metal/ceramic combinations, as well as porosity distributions, namely uniform (or even) and random (or uneven) porosity patterns, are also considered, and the effective material properties of the graded porous structure are determined via a modified power-law function. Two types of applied thermal loads are considered, namely Uniform and nonuniform thermal load (UT, NUT) with temperature-dependent (TD) and independent (TID) mechanical properties. The Green-Lagrange formulation, variational method, and a numerical iterative algorithm are applied to solve the governing equations with porosity and thermal dependent coefficients. To verify our results, various numerical comparisons are conducted on critical temperature buckling of plates and spherical shells, and they are compared with available results where a close correlation is observed. The influence of thermal loads, porosity volume fraction, types of porosity patterns, temperature dependency, and geometrical aspects on the thermal buckling behavior of FG porous plates and shells are scrutinized through different parametric studies.

Recent developments in micro and nanoencapsulation are promising tools to encounter the different limitations of essential oil formulations, enhance their functionalities, and protect them from the external environmental conditions. This review addresses the current studies and progresses related to the development of encapsulated essential oils using different systems and carrier material types. It also focuses on the formation methods used with the subsequent physicochemical characterization of the developed particles. Moreover, this review considers the factors affecting the release of essential oils with the different physicochemical release models. The choice of the appropriate formation method as well as the carrier material types and system forms were shown to highly depend on the intended purpose of the encapsulated essential oil formulation. Micro and nanoencapsulation are used to control essential oils’ release properties, enhance the various characteristics of essential oils, and allow to expand applications in different fields. This review provides the optimal conditions for micro and nanoencapsulation of essential oil formulations based on the intended end uses.

A process for the development, characterization and correlation of composite materials for 3D printing is presented, alongside the processing of a polymer-ceramic functional composite using fused deposition modeling (FDM). The composite was developed using acrylonitrile butadiene styrene (ABS) as the matrix material filled with barium titanate (BT) micro-powder up to 35 vol % (74.2 wt %). The ABS-BT composites exhibited a shear thinning behavior with increasing ceramic content. The composite was 3D printed into structural and functional test samples using FDM by adapting and optimizing the print parameters. Structural characterization revealed increasingly brittle behavior at higher filler ratios, with the ultimate tensile strength falling from 25.5 MPa for pure ABS to 13.7 MPa for the ABS-35 vol % BT composite. Four-point flexural tests showed a similar decrease in flexural strength with increasing ceramic content. Functional characterization revealed an increase in the relative permittivity at 200 kHz from 3.08 for pure ABS to 11.5 for the composite with 35 vol % BT. These results were correlated with the Maxwell-Garnett and Jayasundere-Smith effective medium models. The process described in this work can be used for other 3D printing processes and provides a framework for the rapid prototyping of functional composites into functional parts with reliable properties. The ABS-BT composite shows promise as a functional dielectric material, with potential applications as capacitors and light-weight passive antennas.

The New Advanced Telescope for High ENergy Astrophysics (NewAthena) will be the largest space‐based X‐ray observatory ever built. It will have an effective area above 1.1 m2 at 1 keV, which corresponds to a polished mirror surface of about 300 m2 due to the grazing incidence. As such a mirror area is not achievable with an acceptable mass even with nested shells, silicon pore optics (SPO) technology will be utilized. In the PTB laboratory at BESSY II, two dedicated beamlines are in use for their characterization with monochromatic radiation at 1 keV and a low divergence well below 2 arcsec: the X‐ray Pencil Beam Facility (XPBF 1) and the X‐ray Parallel Beam Facility (XPBF 2.0), where beam sizes up to 8 mm × 8 mm are available while maintaining low beam divergence. This beamline is used for characterizing mirror stacks and controlling the focusing properties of mirror modules (MMs) – consisting of four mirror stacks – during their assembly at the beamline. A movable CCD based camera system 12 m from the MM registers the direct and the reflected beams. The positioning of the detector is verified by a laser tracker. The energy‐dependent reflectance in double reflection through the pores of an MM with an Ir coating was measured at the PTB four‐crystal monochromator beamline in the photon energy range 1.75 keV to 10 keV, revealing the effects of the Ir M edges. The measured reflectance properties are in agreement with the design values to achieve the envisaged effective area. Mirror modules for the optics of the X‐ray observatory NewAthena are assembled and characterized at dedicated synchrotron radiation beamlines. The reflectance of a fully assembled and coated module was determined in a wide energy range.

Abstract The human gastrointestinal tract harbors a heterogeneous and complex microbial community, which plays a key role in human health. The gut microbiota controls the development of the immune system by setting systemic threshold for immune activation. Glycoconjugates, such as lipopolysaccharides, from gut bacteria have been shown to be able to elicit both systemic proinflammatory and immunomodulatory responses. This phenomenon is particularly intriguing considering that the immune system is charged with the task to distinguish the beneficial microbes from the pathogens, even if the commensal bacteria have molecular patterns resembling those of the pathogenic counterparts. Therefore, the importance of the chemical structure of these macromolecules in fine tuning this delicate equilibrium is beyond question. This review offers an overview of the current understanding of chemical peculiarities of the lipopolysaccharides isolated from the gut microbiota, and their relationships to their biological activity in terms of immune system maturation and development. The gut microbiota lipopolysaccharides: the poorly explored world that can change the perception of endotoxins from harmful to beneficial.

Antigenic characterization of emerging and re-emerging viruses is necessary for the prevention of and response to outbreaks, evaluation of infection mechanisms, understanding of virus evolution, and selection of strains for vaccine development. Primary analytic methods, including enzyme-linked immunosorbent/lectin assays, hemagglutination inhibition, neuraminidase inhibition, micro-neutralization assays, and antigenic cartography, have been widely used in the field of influenza research. These techniques have been improved upon over time for increased analytical capacity, and some have been mobilized for the rapid characterization of the SARS-CoV-2 virus as well as its variants, facilitating the development of highly effective vaccines within 1 year of the initially reported outbreak. While great strides have been made for evaluating the antigenic properties of these viruses, multiple challenges prevent efficient vaccine strain selection and accurate assessment. For influenza, these barriers include the requirement for a large virus quantity to perform the assays, more than what can typically be provided by the clinical samples alone, cell- or egg-adapted mutations that can cause antigenic mismatch between the vaccine strain and circulating viruses, and up to a 6-month duration of vaccine development after vaccine strain selection, which allows viruses to continue evolving with potential for antigenic drift and, thus, antigenic mismatch between the vaccine strain and the emerging epidemic strain. SARS-CoV-2 characterization has faced similar challenges with the additional barrier of the need for facilities with high biosafety levels due to its infectious nature. In this study, we review the primary analytic methods used for antigenic characterization of influenza and SARS-CoV-2 and discuss the barriers of these methods and current developments for addressing these challenges.

Plant fibers have become a highly sought-after material in the recent days as a result of raising environmental awareness and the realization of harmful effects imposed by synthetic fibers. Natural plant fibers have been widely used as fillers in fabricating plant-fibers-reinforced polymer composites. However, owing to the completely opposite nature of the plant fibers and polymer matrix, treatment is often required to enhance the compatibility between these two materials. Interfacial adhesion mechanisms are among the most influential yet seldom discussed factors that affect the physical, mechanical, and thermal properties of the plant-fibers-reinforced polymer composites. Therefore, this review paper expounds the importance of interfacial adhesion condition on the properties of plant-fiber-reinforced polymer composites. The advantages and disadvantages of natural plant fibers are discussed. Four important interface mechanism, namely interdiffusion, electrostatic adhesion, chemical adhesion, and mechanical interlocking are highlighted. In addition, quantifying and analysis techniques of interfacial adhesion condition is demonstrated. Lastly, the importance of interfacial adhesion condition on the performances of the plant fiber polymer composites performances is discussed. It can be seen that the physical and thermal properties as well as flexural strength of the composites are highly dependent on the interfacial adhesion condition.