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Purpose: The constitutive parameters of viscoelastic materials, such as storage modulus and loss factor, usually have frequency-dependent characteristics. The combination of polymers with different reinforcement and fillers usually exhibits various mechanical characteristics, which makes the identification of the material properties of viscoelastic materials a challenging task. The present study proposes an inverse identification technique based on a neural network optimization (NNO) algorithm to characterize the frequency-dependent material properties of a viscoelastic material. Methods: To this end, a symmetric three-layered sandwich plate is considered having face layers of isotropic elastic material and a core layer of viscoelastic material. The experimental free vibration tests are performed using the impact hammer method to determine resonant frequencies and modal loss factors for various eigenmodes. In addition, a numerical model of the sandwich plate is developed to determine vibrational responses utilizing the finite element method. The vibration-based material parameter identification technique is implemented based on the NNO algorithm. The identified material parameters are then compared with the experimental dynamic mechanical analysis (DMA) test results. Furthermore, a numerical parametric study is performed considering the optimized viscoelastic material properties to investigate the influence of various geometrical and structural factors on the free vibration response of the sandwich plate. Results: The identified results are in excellent agreement with the experimental DMA test results affirming the robustness of the proposed inverse technique. The parametric study not only investigates the effect of various structural and geometric parameters on the dynamic response of the sandwich plate but also verifies that the calibrated properties are both realistic and physically meaningful. Conclusions: The proposed algorithm is a useful and efficient tool for inverse identification of the constitutive properties, and this approach can be extended for the calibration of other parameters (constitutive or not) for a variety of viscoelastic materials in any field of application. This study is a critical step forward in understanding viscoelastic materials and their frequency-dependent behaviorur. [ABSTRACT FROM AUTHOR]

This paper aims to study the dynamic response and damage of airtight protective doors of nuclear power plants subjected to tornado and wind-borne missile impact. Firstly, a safety performance evaluation method is proposed, considering the structural characteristics of the airtight protective door and relying on support rotation and airtightness. Then, the commercial finite element (FE) program LS-DYNA is utilized to perform the numerical simulations of airtight protective doors in nuclear power plants exposed to tornadoes and wind-borne missile impacts. Subsequently, the parameter analysis method is employed to investigate the impact of keel quantity, size and arrangement, door panel thickness, door core material, and boundary conditions on the dynamic response, airtightness, and failure mode of the airtight protective door. The results show that tornado wind pressure has little effect on the resistance of airtight protective doors and that the impact load of wind-borne missiles plays a leading role. The number and thickness of the keel have significant effects on the force transfer mode and failure mode of airtight protective doors. The thickness of the door panel has a great influence on the damage mode and airtightness of airtight protective doors. The door core improves the local resistance of the airtight protective door to a certain extent, and foam aluminum material has a better energy absorption effect. The change in boundary conditions has little influence on the resistance of airtight protective doors. [ABSTRACT FROM AUTHOR]

A deep understanding of the material parameters and the behavior of sandwich panels, which are used in the construction industry as roof and façade cladding, is important for the design of these construction components. Due to the constant changes in the polyurethane (PU) foams used as a core material, the experimental database for the current foams is small. Nowadays, there is an increasing number of failures of façade and roof panels after installation. This article presents a variety of experimental investigations on sandwich panels from two manufacturers with a core of polyisocyanurate (PIR) rigid foam (density: 40 kg/m3). As part of this study, compression, tension, shear, and bending tests were performed in several spatial directions and over the range required by the standard. The results of the tests showed the orthotropy of the core material and the dependence of the material on the direction and type of load. The stress-strain curves showed linear and non-linear areas. Using the data from this experimental study, a numerical model was implemented which utilized the Hill yield criterion to represent the orthotropy of the core material. The present investigation suggests that the classical von Mises failure criterion, used in many studies, is not suitable for the foam system applied in these sandwich panels. Instead, the Tsai–Wu criterion is more appropriate for defining the failure stresses. [ABSTRACT FROM AUTHOR]

A novel polymeric microcapsule was designed and synthesized using perfluoropolyether silane (PFPE-silane) as a superhydrophobic core material and ethyl cellulose (EC) as a shell material. The effects of the stirring rate and the core-to-shell ratio on the synthesized microcapsules were investigated. The physicochemical properties of the polymeric microcapsules were evaluated using scanning electron microscopy, fourier transform infrared spectroscopy, thermogravimetric analysis, laser particle size analysis, and wettability analysis. The results showed that when the stirring rate was 650 rpm and the core-to-shell ratio was 1:1, well-distributed and uniformly dispersed microcapsules could be obtained. The results also indicated that the prepared polymeric microcapsules were spherical particles with micropores on the surface, and they had an average particle size of 165.71 μm. The EC shells could effectively prevent the thermal decomposition of PFPE-silane during cement hydration, and the PFPE-silane also exhibited excellent hydrophobicity. The specially designed structure of this polymeric microcapsule suggests its potential for enhancing the corrosion resistance of reinforced concrete structures. [ABSTRACT FROM AUTHOR]

Highlights: 3D printable functional inks incorporated with graphene and carbon nanotube nanoparticles were well-formulated by manipulating their rheological performance The frame with ultralight structure (0.076 g cm−3) and high-efficiency electromagnetic interference shielding (61.4 dB) was assembled 3D-printed c-SE module was in situ integrated onto the electronics, affording multiple functions of electromagnetic compatibility and thermal dissipation. Electromagnetic interference shielding (EMI SE) modules are the core component of modern electronics. However, the traditional metal-based SE modules always take up indispensable three-dimensional space inside electronics, posing a major obstacle to the integration of electronics. The innovation of integrating 3D-printed conformal shielding (c-SE) modules with packaging materials onto core electronics offers infinite possibilities to satisfy ideal SE function without occupying additional space. Herein, the 3D printable carbon-based inks with various proportions of graphene and carbon nanotube nanoparticles are well-formulated by manipulating their rheological peculiarity. Accordingly, the free-constructed architectures with arbitrarily-customized structure and multifunctionality are created via 3D printing. In particular, the SE performance of 3D-printed frame is up to 61.4 dB, simultaneously accompanied with an ultralight architecture of 0.076 g cm−3 and a superhigh specific shielding of 802.4 dB cm3 g−1. Moreover, as a proof-of-concept, the 3D-printed c-SE module is in situ integrated into core electronics, successfully replacing the traditional metal-based module to afford multiple functions for electromagnetic compatibility and thermal dissipation. Thus, this scientific innovation completely makes up the blank for assembling carbon-based c-SE modules and sheds a brilliant light on developing the next generation of high-performance shielding materials with arbitrarily-customized structure for integrated electronics. [ABSTRACT FROM AUTHOR]

In this work, M@Pd/N (M = cobalt, nickel; N = multi-walled carbon nanotube, reduced graphene oxide) anodic electrocatalysts are synthesized and studied for formate oxidation, and used directly in formate-hydrogen peroxide fuel cells (DFHPFCs) for the first time. The effect of core materials (M = cobalt, nickel) on the activity of M@Pd/MWCNTs for formate oxidation has been studied. For this purpose, a Co@Pd/MWCNT electrocatalyst is synthesized using a two-step reduction method. Comparing the electrochemical surface area (ECSA), the formate oxidation current density (Ip) and onset potential of formate oxidation (Eons) values of Co@Pd/MWCNTs and Ni@Pd/MWCNTs showed that the presence of Ni in the core instead of Co improved the catalytic performance of the M@Pd/MWCNT catalyst due to the synergistic effects between Ni and Pd. The ECSA and Ip values of the Ni@Pd/MWCNTs are 1.01 and 1.78 times higher than those of Co@Pd/MWCNTs. After optimizing the core material, in the next step, the effect of the catalyst support on the performance of Ni@Pd nanoparticles is evaluated. Comparing the ECSA, Ip and Eons values of Ni@Pd/MWCNTs and Ni@Pd/rGO showed that Ni@Pd/rGO performs better for formate oxidation because of the high surface area and conductivity of rGO compared to MWCNTs. The ECSA and Ip values of Ni@Pd/rGO are 1.09 and 1.57 times higher than those on Ni@Pd/MWCNTs. Finally, the effect of these electrocatalysts in DFHPFC is evaluated and the results are in good agreement with the three electrode results. The maximum power density of the Co@Pd/MWCNTs, Ni@Pd/MWCNTs and Ni@Pd/rGO is 49.90, 62.29 and 107.29 mW cm−2, respectively. [ABSTRACT FROM AUTHOR]

Purpose: The paper shows a preliminary study of the basic strength parameters of printed parts made of biocompatible polymers with ceramic layers applied to increase the strength of the tool cutting surface. Methods: The specimens were made from different materials and using different 3D printing technologies and the working surfaces that will eventually form the cutting element of the tool were coated with Al2O3. Gloss tests were conducted, properties of the coating, a scratch test of the coated surface, also evaluated surface topography. Results: Based on the conducted research, it was found that polymeric materials are characterized by sufficient strength and can be used for disposable tools, however, the use of thin layers of Al2O3 significantly increases the surface strength parameters, which may have a significant impact on the reliability and durability of the tools. The polymer surface covered with an Al2O3 layer is characterised by increased scratch resistance ranging from 24% to 75% depending on the core material and printing technology. The gloss of the surfaces is disproportionately low compared to currently used metal tools, which indicates that they can be used in endoscopic procedures. Conclusions: Based on the conducted research, it was found that the use of thin layers of Al2O3 covering polymer 3D prints is an excellent way to increase strength parameters such as scratch resistance, tribological parameters and light reflections arising on the surface as a result of endoscopic lighting are disproportionately small compared to metallic biomaterials. This gives great hope for using polymer 3D prints for personalised neurosurgical tools. [ABSTRACT FROM AUTHOR]

A dual-rotor yokeless and segmented armature (YASA)-type axial-flux permanent magnet (AFPM) motor with a surface-mounted permanent magnet (SPM) array type was developed for urban air mobility (UAM) aircraft in this work. The proposed AFPM motor had rated and peak output powers of 75.5 and 104 kW, respectively, with rated and peak rotational speeds of 1800 rpm. To achieve a high torque, a cobalt–iron alloy core material was used for the stator core. The prototype AFPM motor, developed by KSEP in the Republic of Korea, was successfully manufactured and verified through experimentation. Additionally, the thermal stability of the winding and permanent magnets (PMs) was confirmed with a water-cooling system. A structure analysis of the proposed AFPM motor was conducted due to the detachment of an uneven air-gap length in the prototype AFPM motor. An output performance comparison based on core materials for the stator and rotor was carried out to explore the material cost reduction. Subsequently, the design for performance improvement by applying a Halbach permanent magnet (HPM) array type was investigated for further research. [ABSTRACT FROM AUTHOR]

The use of nanoemulsions as encapsulation systems for active ingredients, such as cinnamon oil, has been studied. A surfactant based on polyoxyethylene glycerol esters from coconut/palm kernel oil has been used. The nanoemulsions were obtained by the two most commonly low-energy emulsification methods, the composition inversion phase (PIC) and the temperature inversion phase (PIT) methods. Nanoemulsions were successfully obtained by both methods, with very small droplet sizes (5–14 nm) in both cases, but a greater stability was observed when the PIT method was used. Nanoemulsions were encapsulated by external gelation using two different polysaccharides, alginate or chitosan, dissolved in the continuous phase of the nanoemulsion. Then, the nanoemulsion was dropped into a bath with a gelling agent. To improve the release control of cinnamon oil and avoid the burst effect, beads prepared with one of the polysaccharides were coated with the second polysaccharide and then gelled again. Double gelled beads were successfully obtained, the core with chitosan and the outer layer (shell) with alginate. SEM images showed the morphology of the single beads presenting high porosity. When the beads were coated, the porosity decreased because the second polysaccharide molecules covered the pre-existing pores. The smoother surface was obtained when this second layer was, in turn, gelled. The release patterns at pH = 2 and pH = 7 were studied. It was observed that the double gelled bead provided a more gradual release, but maintained approximately the same amount of final released oil. The release patterns were fitted to the Korsmeyer-Peppas model. The fitting parameters reflected the effect of the different coating layers, correlating with different diffusion mechanisms according to the bead core and shell materials. [ABSTRACT FROM AUTHOR]

• Homogenisation effects on the vibrations of mutlilayered microbeams with an AFG core and metal foam face layers are studied. • Differences in natural frequencies between homogenisation schemes vary with varying power gradation constant. • Higher length scale parameter leads to larger differences in natural frequencies between homogenisation schemes. • Relationship between the rotational natural frequency and the functionally graded core thickness is not linear. This study assesses the significance of homogenisation models in theoretically analysing the vibrations of three-layered microbeams with a core composed of axially functionally graded (AFG) material and with upper and lower face layers composed of metal foam material, especially when the third order shear deformation beam theory and the modified couple stress theory are used. The material of the core is assumed to vary following a power gradation profile. The range of homogenisation schemes, including the Voigt model, Reuss model, Voigt-Reuss-Hill model, Tamura model, Mori-Tanaka model, lower and upper bounds of Hashin-Shtrikman, and the local representative volume element (LRVE) model, are utilised to approximate the material properties of the AFG core. The upper and lower layers of metal foams are modelled using the closed-cell and open-cell solid porosity models. The coupled motion equations are solved for the natural frequencies of the system for the transverse, rotational and axial directions. A software-based finite element analysis (FEA) study of two simplified macrobeam systems was undertaken and the agreement between the FEA and numerical results, using the presented theoretical method, is found to be excellent. It has been confirmed that the homogenisation schemes have a notable effect on the mechanical properties of the AFG core, and hence on the coupled translational-rotational motion's natural frequencies. The largest difference in natural frequencies between different homogenisation schemes is found with a power gradation constant of approximately 0.53. A larger disparity of natural frequencies between different homogenisation methods was seen with an increase in the thickness of the AFG core and the microbeam's length-scale parameter of multilayered porous microbeam. The results of this study highlight the significance of homogenisation scheme employed when investigating the vibrations of a multilayered microbeam with an AFG core and metal foam porous face layers. [ABSTRACT FROM AUTHOR]

This paper presents a method to identify the dynamic mechanical properties of soft not self-supporting viscoelastic materials at high frequencies using sandwich beams. The motivation of this alternative method comes from the fact that the method of Ross, Kerwin and Ungar (RKU), proposed by the standard ASTM E 756-05, adds structural rigidity to the sandwich as shear increases, for example at high frequencies, and consequently, the stiffness of the core material is underestimated. The proposed method is based on a homogenization technique for sandwich beams that takes into account quadratic shear stress in the formulation, instead of a constant shear as the RKU method. To prove its worth, the properties of a soft polymer are identified by both methods from experimental transmissibility measures carried out on a sandwich beam up to 2500 Hz. Then, finite element simulations are performed using the obtained material properties to compare the numerical transmissibility functions with the experimental one. A numerical comparison for the case of a sandwich beam with a thicker viscoelastic core is also completed, proving the improvement in the stiffness and damping properties identification in the high frequency range by considering quadratic shear in the formulation. As a result, the identified mechanical properties by the proposed method are more accurate at high frequencies and for thicker core beams, i.e., when the shear effect is significant. [ABSTRACT FROM AUTHOR]

In this work we utilize the recently upgraded Thomson scattering diagnostic to resolve density and temperature plasma profiles after pure deuterium and mixed neon/deuterium shattered pellet injections (SPIs) on DIII-D. This allows us to study individual components of the staggered scheme proposed for disruption mitigation on ITER, consisting of a low-Z material SPI followed by a delayed high-Z SPI. Obtained spatio-temporal density profiles exhibit very different dynamics after dominantly neon and pure deuterium SPIs. The neon SPI causes a fast radiative plasma collapse in a few milliseconds and results in almost flat density profile once the impurity mixes with the plasma during and after the thermal quench (TQ). The deuterium SPI leads to a disruption delayed by ten and more milliseconds, but very limited core fueling can be observed before the disruption. Even during and after the TQ, the edge deuterium density significantly exceeds the core density. 1D transport modeling suggests that this poor core fueling can be explained by strong outward grad-B-induced drift of the injected deuterium. Preliminary simulations show that larger pellet shards and greater injected quantity can be used to improve the penetration of the low-Z material into the core. These results call for optimization and further evaluation of the staggered SPI on ITER. [ABSTRACT FROM AUTHOR]

Thermoelectric materials and devices have the potential to directly convert heat into electricity, making them crucial for advancing the energy structure system and achieving the dual-carbon goal. However, the conventional methods of preparing thermoelectric materials and designing devices still face significant challenges, limiting the widespread application of thermoelectric technology. Ferromagnetic metal heterostructured nanomultilayers play a crucial role in generating, transporting, and detecting spin currents. Studying the properties and physical mechanisms of spin-dependent magnetic-thermal-electrical effects in the core material is essential for advancing spin thermoelectrics in the future. In this paper, we investigate the spin-related thermoelectric effects in artificial spin-valve heterostructured nanomultilayers. The spin-current generating layer is made of rare-earth garnet, while the spin-current detecting layer consists of ferromagnetic alloy thin films with different compositions of Fe–Co. It is being investigated to obtain thermal voltage signals with excellent stability and high resolution as well as to achieve the amplification and positive/negative adjustment of these signals. This study can serve as a reference for designing thermoelectric materials and aiding in the development of future high-efficiency spin-thermoelectric conversion devices. [ABSTRACT FROM AUTHOR]

Creating multilayered channels for mimicking human blood vessels in thick tissues is the main challenge to overcome in organ biofabrication. Current three-dimensional (3D) printing strategies cannot effectively manufacture hollow channels with multiple layers. This study aims to propose a coaxial nozzle-assisted embedded 3D printing method in which core-shell filaments can be formed in a yield-stress matrix bath by extruding different ink materials through the corresponding channels. The materials selected for the core ink, shell ink, and matrix bath are Pluronic F127 (F127) and calcium chloride (CaCl2), sodium alginate (NaAlg), and poly(ethylene glycol) diacrylate (PEGDA) and nanoclay, respectively. After crosslinking the matrix bath and shell, the core layer made from the sacrificial ink (F127) is removed to generate a single-layered, hollow channel. In this work, the effects of ink material properties and operating conditions on core-shell filament formation have been systematically studied. The rheological and mechanical properties of the yield-stress matrix bath have been characterized as well. A thick tissue-like structure with embedded single-layered, hollow channels has been successfully printed for demonstration. Since it is feasible to design coaxial nozzles with a core-shell-shell architecture, the proposed method is technically extendable to create double-layered channels within a cellular tissue construct, accurately mimicking human blood vascular networks in thick tissues in the future. [ABSTRACT FROM AUTHOR]

This paper describes a simple and interesting application of structural equation modeling for a single lecture in an undergraduate econometrics course to introduce students to the concept of using data to recover latent variables. The application centers around using hourly observations on ride wait times at Disney's Magic Kingdom to infer how crowded it is at the theme park. Pedagogically, the material is presented in the context of the linear regression model, so the discussion works to enhance students' understanding of core material, not to introduce new disparate methods. The application provides interesting economic-based insights, like which ride's wait times are categorically most informative about how crowded it is at the park. [ABSTRACT FROM AUTHOR]

In many small wind turbine blades, the interior space between laminate skins is filled by a material core. The mechanical properties of the core are much less important than its density, which must be low to reduce the moment of inertia as high inertia increases both the starting time of the turbine and the gyroscopic loads on the blades. In this paper, we use, for the first time, the petiole of the miriti palm (PMP) as the core of four small blades, in order to analyze its effect on turbine starting performance. PMP is abundant in the Amazon region and harvesting it does not destroy the palm because the petiole regrows; therefore, harvesting is fully sustainable and may well have a major role in increasing the sustainability on wind turbine manufacturing. We consider the benefits of using the easily worked petiole for the core in terms of manufacturing, as demonstrated by the construction of a 0.598 m blade. PMP is less dense on average than alternative materials, such as expanded polystyrene and balsa wood. The starting performance is an important issue for small wind turbines. It is evaluated using a quasi-steady model, in which blade element momentum theory is coupled to Newton's Second Law. The low density of the small blade made using petiole of the miriti reduces the starting time by 10% when compared with expanded polystyrene and 42% when compared to balsa wood. [ABSTRACT FROM AUTHOR]

In this study, natural fiber reinforced polymer foam core layered composites were produced for the automotive industry. Sheep wool was used as natural fiber. Polymer foam with a single layer XPS foam structure was used as the core material. XPS foams and fibers are bonded to the upper and lower sides of the foams with the help of resin. Samples were produced with one and two layers on both sides, with a total of two and four layers. Production was carried out using the vacuum bagging method using the manual laying method. After the production was completed, it was cut to dimensions in accordance with the standards and experiments were carried out. Compression tests, three-point bending tests and low-speed impact tests were carried out to analyze the energy absorption capabilities of the produced samples. As a result of the experiments, it was determined that the samples with a total of two floors provided better performance than the samples with a single layer. In the impact tests, rebound occurred in the double-layered samples in the 10 J impact tests, and punctures or stabbings were detected in the 20 J tests. [ABSTRACT FROM AUTHOR]

Investigation of four different surface-shaping and finishing sequences is carried out on the surface integrity of a WC-10Co hardmetal grade. The surface conditions include grinding, electrical discharge machining and grinding, followed by mechanical and dry-electrochemical polishing using the DryLyte® technology. The evaluation includes the measurement of roughness, residual stresses, the Vickers hardness, indentation fracture toughness determination and the damage induced by conical contact response. By scanning electron microscopy, a systematic and detailed examination of the residual imprints is carried out to determine the critical loads for damage initiation and development across the different surface conditions. The results indicate that the use of dry-electrochemical polishing enables the attainment of polished surfaces without any corrosive damage to the metallic binder. Moreover, it retains the mechanical attributes reminiscent of the core material, comprising 85% that were initially induced via grinding. [ABSTRACT FROM AUTHOR]

Purpose: This work presents the comparative damping performance of conventional viscoelastic material (VEM), 0–3 viscoelastic composite (VEC), and viscoelastic particulate composite (VEPC) damping layers in the active/passive constrained layer damping mechanism for plate vibration. Methods: In the present study, passive and active–passive damping mechanisms, namely constrained layer damping (CLD) and active constrained layer damping (ACLD) are analysed to control the plate vibration. The CLD mechanism is achieved in both symmetric and asymmetric sandwich plate configurations where damping material lies at the core. In contrast, for the ACLD mechanism, the top face layer in the asymmetric sandwich plate is replaced by an extensional-mode piezoelectric actuator. A closed-loop finite element (FE) model is first derived for the damping analysis of sandwich plates following the layer-wise first-order shear deformation theory and velocity-feedback control strategy for the ACLD mechanism. Subsequently, the utilization of the same FE model for damping analysis of the CLD mechanism of symmetric and asymmetric sandwich plates is demonstrated for each of the three kinds of damping layers. Results and Conclusions: The modal loss factors and frequency responses for each of the three kinds of damping layers in CLD/ACLD treated plates are estimated for the comparative study. The results reveal that damping performance of 0–3 VEC or VEPC layer in CLD/ACLD mechanism is significantly more than that for the conventional VEM layer. The VEPC layer may be used for the CLD mechanism in a symmetric sandwich configuration, while 0–3 VEC is a suitable one for the same damping mechanism through an asymmetric sandwich configuration. Moreover, 0–3 VEC may also be more suitable for the ACLD mechanism due to the magnification in active–passive damping performance compared to VEPC. [ABSTRACT FROM AUTHOR]

The performance of an internal permanent magnet MISC machine (IPMMM) is improved by its cylindrical rotor, which dampens torque ripple. Changing the stator and rotor core materials, comparing with torque values to identify efficient motor and keeping that in consent, then change the magnet material for better ripple torque. The change in the rotor materials to vary the torque by the rotor angle is analyzed. The finite element method is applied to a MISC motor operating at 290 V, 20 A, and 3000 r/min with the goals of increasing torque and decreasing torque ripple. In this machine, changing stator and rotor materials improves the torque. The results are calculated and analyzed numerically, with the results being virtualized graphically. [ABSTRACT FROM AUTHOR]

The precise quantification of a dielectric waveguide core thickness, core width, core refractive index, and cladding refractive index across a wafer is critical for greater consistency and accuracy in photonic circuit fabrication. However, accurate wafer-scale measurements of these parameters have not yet been demonstrated. We have previously described a method for extracting these four parameters simultaneously from silicon nitride waveguides using unbalanced Mach–Zehnder interferometers on a single die. In this work, we show that this technique can be scaled to characterize these photonic parameters across an entire 300 mm wafer. The refractive indices of the core and cladding materials are found with relative standard deviations of the mean of 0.07% and 0.03%, respectively. The core width offset (bias) and thickness are found with relative standard deviations of 0.3% (2.6 nm) and 0.5% (1.1 nm), respectively. The extracted parameter maps suggest a radial variation of material indices and a planar variation of geometric parameters. We verify the extracted parameters by accurately predicting the performance of an unbalanced Mach–Zehnder interferometer and the degeneracy between different modes in straight waveguides. [ABSTRACT FROM AUTHOR]

Sandwich composites are often used as primary load-bearing structures in various industries like aviation, wind, and marine due to their high strength-to-weight and stiffness-to-weight ratios, but they are vulnerable to damage from Low-velocity-impact (LVI) events like dropped tools, hail, and birdstrikes. This often manifests in the form of Facesheet-Core-Debonding (FCD) and is often termed Barely-Visible-Impact-Damage (BVID), which is difficult to detect and can considerably reduce mechanical properties. In general, a balsa core sandwich is especially vulnerable to FCD under LVI as it has poorer adhesion than synthetic core materials. A cork core sandwich does show promise in absorbing LVI with low permanent indentation depth. This paper also reviews surface treatment/modification as a means of improving the adhesion of composite core and fiber materials: key concepts involved, a comparison of surface free energies of various materials, and research literature on surface modification of cork, glass, and carbon fibers. Since both balsa and cork have a relatively low surface free energy compared to other materials, this paper concludes that it may be possible to use surface modification techniques to boost adhesion and thus FCD on balsa or cork sandwich composites under LVI, which has not been covered by existing research literature. [ABSTRACT FROM AUTHOR]

In the numerical simulation of earth-rock dam, accurate and reliable mechanical parameters of the dam material are the important basis for dam deformation predictions and dam safety evaluations. Based on the deformation monitoring data of Luding core wall rockfill dam, the rheological parameters of rockfill and core wall materials are inverted in this paper. Combined with the actual filling and impoundment process of the dam, the numerical simulation is carried out, and the stress deformation and differential settlement of the dam after completion and impoundment are analyzed. The results showed that the stress deformation results of the dam based on the inversion parameters were in good agreement with the actual deformation. The horizontal displacement, settlement, and principal stress of the dam during the completion period were symmetrically distributed along the core wall. The maximum horizontal displacement occurred at the main dam on both sides of the core wall and the upstream and downstream dam slopes, and the maximum settlement occurred in the middle of the core wall. During the impoundment period, under the action of reservoir water pressure and upstream rockfill wetting deformation, the deformation and stress of the dam body no longer met the symmetrical distribution law, and the maximum horizontal displacement of the dam body during the impoundment period was located at 2/3 of the upstream dam slope. The maximum settlement of the dam body was located at 1/2 of the dam height. The maximum principal stress on the upstream side of the core wall was located on the left side of the bottom of the core wall, and the minimum principal stress was also located on the left side of the bottom of the core wall. The simulation results of the deformation and stress met the general law of earth-rock dam engineering. During the completion period, the deformation inclination of the dam crest was less than 1%. During the impoundment period, the deformation inclination of the dam crest area increased due to the wetting deformation of the upstream rockfill material. At the same time, the deformation inclination of the dam crest axis was larger than that of the upstream and downstream sides, and the deformation inclination of the dam crest at the middle of the valley was the largest, but it did not exceed 3%, that is, there would be no longitudinal cracks, which is consistent with the actual situation. The research results can better predict the stress deformation and crack of the dam body, and provide important support for dam safety evaluations. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries (SIBs) have attracted attention due to their potential applications for future energy storage devices. Despite significant attempts to improve the core electrode materials, only some work has been conducted on the chemistry of the interface between the electrolytes and essential electrode materials. Therefore, the different cathode–electrolyte interfaces (CEIs) that form between various cathode materials and liquid electrolytes for SIBs are briefly reviewed, and the requirements of CEI performance in low‐temperature SIBs. Modifying the cathode materials and electrolyte formulas offers an efficient strategy for CEI enhancement. The summary and analysis, given in this article, may serve as a reference for the development of better sodium‐ion batteries. [ABSTRACT FROM AUTHOR]

This article explores recent advancements in dental post and core techniques aimed at optimizing both strength and aesthetics in restorative dentistry. Dental posts and cores play a critical role in providing structural support for severely damaged teeth, enabling the restoration of form and function. With ongoing innovations in materials and methodologies, practitioners now have a diverse array of options to enhance the longevity and esthetic appeal of dental restorations. This article reviews key considerations in selecting appropriate post and core materials, techniques for achieving optimal bond strength, and strategies for maximizing esthetic outcomes. By incorporating these advancements into clinical practice, dental professionals can effectively address the challenges associated with compromised tooth structure, ultimately improving patient satisfaction and long-term treatment success. [ABSTRACT FROM AUTHOR]

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As the core material that affects the performance of OLED devices, the demand for performance improvement of OLED materials is urgent. However, due to the molecular diversity of organic compounds, traditional methods of development are inefficient and expensive. Recently, the machine learning (ML) approach has attracted increasing attention in the field of organic luminescent materials, which can learn from the existing results and provide the relation between the input features to the output performance. By constructing the relationship between molecular structure and device performance of OLED, the efficiency of material development is higher and guidance for material design is better provided through the identification of molecular key factors. In this work, we attempt to use the ML approach to explore the quantificational relation between the external quantum efficiency (EQE) of red phosphorescent organic light‐emitting devices (OLEDs) and their material and device structural factors, aiming to screen out the key factors governing the EQE and predict EQE values directly by molecular structure. We established the dataset based on over 1000 device data from experiment, and reduced the number of molecular descriptors to below 35. Currently, the root mean squared error (RMSE) of test set has been lowered to 3.21%. These results provide essential guidance for material screening and experimental device optimization. On this basis, we further designed new red host materials, which have higher EQE, up to 27.56%. It has reached the first‐class level of commercial materials. [ABSTRACT FROM AUTHOR]

The thermal–electric bifunctional devices with isotropic and anisotropic geometries are designed in this paper, which can realize different control functions (invisible sensors and cloaks) of thermal and electric fields. We first theoretically achieve the bifunctions of invisible sensors and cloaks with isotropic and anisotropic geometries. When the material parameters of the core and matrix and the geometric parameters of the core, inner shell, and outer shell are determined, the thermal–electric invisible sensors could be realized. Meanwhile, the invisible sensors will degrade to invisible cloaks as the inner shell material is insulating. The simulations applying the derived material parameters have also been conducted to verify the thermal–electric bifunctions of different circular and confocal elliptical devices. The results show that the thermal–electric bifunctional devices can effectively control the thermal and electric fields, and these devices exhibit perfect performance of the thermal–electric functions of invisible sensors and cloaks. This work presents a new method to realize thermal–electric bifunctional devices and opens a new window to the development of multi-physics field. [ABSTRACT FROM AUTHOR]

Surface stresses, in nano-sized battery anode particles undergoing chemomechanical interactions, have a compressive effect on diffusion-induced stresses. This, on the one hand, improves the mechanical endurance of the particles and, on the other hand, degrades their electrochemical performance. However, this straightforward prediction of an improved mechanical performance is re-evaluated in this work in light of large axial length-increase during lithiation within Si nanowires. Interestingly, we observed that the influence of surface stress on length-increase of nanowires is dependent on the charging conditions (galvanostatic/potentiostatic). The mathematical model we present to capture the sensitive interplay among these effects is based on the finite deformation formulation, considering two-way coupling of diffusion-induced stresses and stress-enhanced diffusion. Additionally, we consider the influence of a constraining material at the core, whose material and geometrical properties can be suitably tuned. Finally, we present a competitive analysis for the overall performance of the anode particles under the combined effects of surface stresses and constraining material to determine the best possible particle sizes for different charging conditions. Such a comprehensive approach strengthens our understanding of different mechanical and electrochemical factors in general chemomechanical interactions involved in various applications of nanostructures. [ABSTRACT FROM AUTHOR]

We present relativistic magnetohydrodynamic modelling of jets running into hydrostatic, spherically symmetric cluster atmospheres. For the first time in a numerical simulation, we present model cluster atmospheres based upon the universal pressure profile (UPP), incorporating a temperature profile for a 'typical' self-similar atmosphere described by only one parameter – M 500. We explore a comprehensive range of realistic atmospheres and jet powers and derive dynamic, energetic, and polarimetric data which provide insight into what we should expect of future high-resolution studies of AGN outflows. From the simulated synchrotron emission maps which include Doppler beaming we find sidedness distributions that agree well with observations. We replicated a number of findings from our previous work, such as higher power jets inflating larger aspect-ratio lobes, and the cluster environment impacting the distribution of energy between the lobe and shocked regions. Comparing UPP and β-profiles we find that the cluster model chosen results in a different morphology for the resultant lobes with the UPP more able to clear lobe material from the core; and that these different atmospheres influence the ratio between the various forms of energy in the fully developed lobes. This work also highlights the key role played by Kelvin–Helmholtz instabilities in the formation of realistic lobe aspect ratios. Our simulations point to the need for additional lobe-widening mechanisms at high jet powers, for example jet precession. Given that the UPP is our most representative general cluster atmosphere, these numerical simulations represent the most realistic models yet for spherically symmetric atmospheres. [ABSTRACT FROM AUTHOR]

Wetting deformation has a significant impact on dam safety, and is one of the leading causes of the long-term deformation of dams. For dams to operate safely, it is crucial to precisely estimate the extent of wetting deformation using a reasonable calculation model. This study describes the wetting deformation behavior of gravelly soil core material observed at a hydropower station using a large-scale triaxial wetting test, and the process, characteristics, and mechanism of the wetting deformation are analyzed. The results show that the direction of the wetting deformation exhibits different behaviors influenced by the stress levels. Compared with the significant changes in the wetting direction observed under low stress levels, the changes in the wetting direction under high stress levels appears to lag behind those in wetting deformation. The source of wetting deformation is thought to be the weakening of a material when it encounters water. Thus, a new calculation model of the wetting deformation of gravelly soil core material is proposed. In this model, the wetting strain ratio is in an exponential relationship with the stress levels, and the new model is used to simulate the triaxial wetting test on the gravelly soil core material; its validity and practicability are further evaluated, providing a new computational approach for analyzing the wetting deformation behavior of dams. [ABSTRACT FROM AUTHOR]

During the consolidation period of vacuum preloading drainage of dredged mud slurry, the clogging behaviors of the filter drainage structural layers and the core boards of prefabricated vertical drains (PVD) determine the drainage capacities of PVD. However, currently, there is a lack of comprehensive research on the evaluation criteria for these two clogging behaviors. Therefore, based on typical dredged mud slurry, typical geomembranes, and raw material core boards with different bending forms, relevant macro and micro-scale experimental studies have been carried out in this study. The research results show that (1) with the application of the gradient ratio test method, the clogging behaviors of filter membranes of PVD under graded vacuum preloading can be effectively simulated. Also, in the design of graded vacuum preloading, characteristics of equivalent pore sizes and pore structures should be emphasized to investigate the suitability of filtration and drainage performance of PVD filter membranes. (2) The compressive yield strength of core board grooves is a key factor influencing the reduction rate of flow capacity. The reduction rate of flow capacity and well resistance increment can be used as comprehensive indicators reflecting the clogging behaviors of core boards, while the bending angles and bending rates of core boards can be used as specific technical indicators. (3) The proposed clogging evaluation criteria for PVD are as follows: a filter membrane gradient ratio (GR) > 4.0, a core board bending rate >60% and a core board bending angle < 45°, or a reduction rate of flow capacity of bending drainage board > 90% or well-resistance increment > 9. Also, these criteria can be incorporated into the control indicators for drainage performance of PVD used in such types of foundations. [ABSTRACT FROM AUTHOR]

We propose and numerically demonstrate chalcogenide based bend M-type fiber for mid-IR supercontinuum (SC) generation through higher order mode (HOM) of LP02. In order to achieve this, we comprise two glass materials such as As2Se3 in core and Ge10As23.4Se66.6 in cladding. M-type index fiber has a special property that the HOM of LP02 is confined into the core region with help of high index ring. The mode field distribution of the proposed fiber is numerically calculated by a finite element method. By optimizing structural dimensions in each bending case, we realize a zero dispersion wavelength, double zero dispersion wavelength effective area and power fraction in core. The simulation results shows the flat anomalous dispersion in the wavelength range of 2.1–2.6µm and 2.5–6.5µm for the core radius 4 and 10 µm, respectively at bending case of 1, 3, and 5 cm. which is important for employing the mature fiber laser technology at mid-IR regions. [ABSTRACT FROM AUTHOR]

The purpose of this research is to demonstrate the use of a new and highly efficient population-based algorithm, known as Heat Transfer Search (HTS), for optimisation of an active magnetic bearing (AMB) system. In this research paper, the HTS algorithm is employed to minimise the overall bearing volume, considering turns per pole pair, the maximum required current, pole width, and coil length as the design variables. Constraints are imposed on the maximum flux density, current density, winding space, and maximum magneto-motive force. It is found that, for the operating conditions considered herein, the Heat Transfer Search algorithm yields around 23% lower bearing volume as compared to that obtained using more popular optimisation techniques such as Genetic Algorithms (GA) and Pattern Search (PS). Finally, a comparative study on the impact of magnetic core material presented herein reveals that Supermendur yields the best results. This is the first attempt to integrate the impact of magnetic core material on the optimisation of the AMB system. [ABSTRACT FROM AUTHOR]

The aims of this study were to systematically review the literature and compare the relative effects of various luting agents on bonding between glass-fiber posts and root canal dentin in short- and long-term aging conditions. The literature was electronically searched in PubMed, Embase, and Scopus. A manual search was performed by scanning the reference lists of the included studies. Two reviewers independently conducted the selection of studies, data extraction, and risk of bias assessment. Pairwise meta-analyses were based on random effect models. Network meta-analyses were conducted within a frequentist framework with a multivariable random effects approach. The standardized mean difference and 95% confidence interval was calculated. One hundred and eighteen studies were included and assessed the effects of five luting agents. For pairwise meta-analyses, in short-term aging conditions, a significantly higher bond strength of self-adhesive resin cement (SARC) compared to etch-and-rinse adhesive composite resin core material (ERCM) in the total, coronal, and middle regions. In long-term aging conditions, a significantly higher bond strength of ERCM compared to etch-and-rinse adhesive resin cement (ERRC) in all regions. Furthermore, SARC showed a significantly higher bond strength compared to self-etch adhesive composite resin core material (SECM) in the total, middle, and apical regions. For network meta-analyses, in the apical region, a significantly higher bond strength of SARC compared to ERRC in both aging conditions. The SARC tended to be the most effective luting agent in bonding between glass-fiber posts and root canal dentin in short- and long-term aging conditions. [Display omitted] • Self-adhesive resin cement is effective in bonding glass-fiber posts to root canal. • Etch-and-rinse adhesive resin cement is ineffective in bonding glass-fiber posts. • Self-etch adhesives exhibit superior short-term bond strength than etch-and-rinse systems. • Composite core materials exhibit superior long-term bond strength than resin cements. [ABSTRACT FROM AUTHOR]

Study Design. A retrospective case series. Objective. This study aims to assess the rates of lumbar interbody cage failures based on their material and manufacturer. Summary of Background Data. Perioperative lumbar interbody cage malfunctions are underreported events in the spine literature and may result in complications. Although the Food and Drug Administration ensures the safety of these devices under physiological conditions after implantation, these devices may experience nonphysiological conditions during implantation, which may be overlooked. Materials and Methods. The MAUDE database was examined for reports of lumbar cage device malfunctions from 2012 to 2021. Each report was categorized based on failure type and implant design. A market analysis was performed by dividing the total number of failures per year for each manufacturer by their approximate yearly revenue from spinal implants in the United States. Outlier analysis was performed to generate a threshold value above which failure rates were defined as greater than the normal index. Results. Overall, 1875 lumbar cage malfunctions were identified. Of these, 1230 (65.6%) were cage breakages, 257 (13.7%) were instrument malfunctions, 177 (9.4%) were cage migrations, 143 (7.6%) were assembly failures, 70 (4.5%) were screw-related failures, and 21 (1.1%) were cage collapses. Of the breakages, 923 (74.9%) occurred during insertion or impaction and 97 entries detailed a medical complication or a retained foreign body. Of the migrations, 155 (88.6%) were identified postoperatively, of which 73 (47.1%) detailed complications and 52 (33.5%) required a revision procedure. Market analysis demonstrated that Medtronic, Zimmer Biomet, Stryker, Seaspine, and K2M exceeded the calculated threshold. Conclusions. Lumbar cages with polyether ether ketone core material failed more frequently by breakage, whereas titanium surface cages failed more frequently by migration. Failure rates varied depending on the manufacturer. Most cage breakages identified in the present study occurred intraoperatively during implantation. These findings call for a more detailed Food and Drug Administration evaluation of these intraoperative malfunctions before commercial approval. [ABSTRACT FROM AUTHOR]

Lithium batteries are promising techniques for renewable energy storage attributing to their excellent cycle performance, relatively low cost, and guaranteed safety performance. The performance of the LiFePO4 (LFP) battery directly determines the stability and safety of energy storage power station operation, and the properties of the internal electrode materials are the core and key to determine the quality of the battery. In this work, two kinds of commercial LFP batteries were studied by analyzing the electrical properties and material properties of the electrodes. After performing the rate and cycle performance tests of the battery cell, differential scanning calorimetry, scanning electron microscope, x-ray diffraction, and inductively coupled plasma were used to explore the performance of electrode materials to establish the correlation between the battery performance and the electrochemical reaction law of the internal materials and further to judge the influence of the key material properties on the battery performance. This work opens up an avenue for technical supervision of energy storage power stations. [ABSTRACT FROM AUTHOR]

To solve the problem of the leakage of phase-change materials and expand the application of clay minerals in the field of phase-change materials, illite and paraffin wax were used for the first time as a new binary hybrid core material with silica as the wall material. Phase-change microcapsules were prepared using the sol–gel method and successfully applied in silicone rubber foams. Differential scanning calorimetry showed that the microcapsules had a melting temperature of 62.99°C and a latent heat capacity of 98.24 J g–1, indicating their good heat-storage capacity. Furthermore, the effectiveness of using illite as a filler for preventing paraffin leakage was demonstrated through 200 thermal cycling tests, which demonstrated a leakage rate of only 2.6% compared to 3.2% exhibited by microcapsules without illite. [ABSTRACT FROM AUTHOR]

Glass Fiber Reinforced Polymer (GFRP) beams have gained attention due to their promising mechanical properties and potential for structural applications. Combining GFRP core and encasing materials creates a composite beam with superior mechanical properties. This paper describes the testing encased GFRP beams as composite Reinforced Concrete (RC) beams under low-velocity impact load. Theoretical analysis was used with practical results to simulate the tested beams' behavior and predict the generated energies during the impact loading. The impact response was investigated using repeated drops of 42.5 kg falling mass from various heights. An analysis was performed using accelerometer readings to calculate the generalized inertial load. The integrated acceleration record and the measured hammer load vs. time data were utilized to determine the generalized bending load and fracture energy. Four forms of energy were calculated at the maximum load. The total energy was calculated and divided into two parts: The first part was gained by the beam's rotational kinetic energy, the bending energy in the specimen, and the elastic strain energy. The second part was the hammer's kinetic energy before striking the beam. The analytical results showed that the bending energy was less than its rotational kinetic energy for the encased GFRP beams and the reference specimens. In contrast, the encased steel beams had high bending energy due to the higher impact load and deflection. Strain energy recorded lower energy values for all specimens with higher bending energy. There is a good agreement between the tested and the calculated inertial and bending force for all beams. The ratio of inertia force to the total impact load for the encased GFRP and encased steel beams to the reference beam is about 9% and 5%, respectively. [ABSTRACT FROM AUTHOR]

The growing interest in green synthesis and multifunctional application of microcapsules is due to their eco-friendly nature, health benefits, safety advantages, controlled release capabilities, and enhanced protection and stability. In this study, chitosan microcapsules were synthesized using a green double emulsion-simple coacervation method. The shell and core materials are derived from plants and are environmentally friendly, while the preparation process does not require volatile organic solvents. Both water-soluble vitamin C (VC) and oil-soluble lemon essential oil (LEO) were loaded as active substances in the chitosan microcapsules. The prepared microcapsules are about 3 μm in size and exhibit good thermal stability. Further modified microcapsules with UV crosslinked monomers could be coated on the fabric to form a functional fabric coating as well as UV crossing linkers. The obtained functional fabric based on chitosan microcapsules has the slow-release property of VC and LEO. The sustained-release VC exhibits a skincare effect and is beneficial to human health. Furthermore, this coated fabric has durable antibacterial properties due to the synergistic effect of LEO and chitosan. This method offers a sustainable solution for creating innovative microcapsules with diverse applications such as medical textiles, home textiles, cosmetics, and more. [ABSTRACT FROM AUTHOR]

Phase change material microcapsules with silica as shell and n-docosane as core material were prepared by interfacial polymerization method, and water-based exterior wall coatings with temperature control were prepared. The results show that when the amount of microcapsule is 30% of mass of waterborne modified propylene solution, the temperature control coating has the best comprehensive performance, has good aging resistance and water resistance, and can withstand up to 18 725 times of scrubbing. The application conditions are further optimized by the thickness of the coating. When the coating thickness is 2 mm, the temperature control effect of the coating is the best. [ABSTRACT FROM AUTHOR]

The article presents the results of work on the use of soft materials in the cores of brushless DC motors (PM BLDC). In order to compare the properties of electric motors, three identical prototypes with a rated speed of 8,000 rpm were built, differing only in the material from which the core was made. In the construction of the cores, amorphous material (ASMM), nanocrystalline material (NSMM) and electrotechnical sheet (Fe-Si) were used. The paper also describes technologies for manufacturing motor cores from soft magnetic materials [ABSTRACT FROM AUTHOR]

Natural food colorants have proven to be just as impactful as artificial ones, with the added advantages of being safer, offering health benefits in addition to instilling organoleptic attributes, exerting multiple benefits as ingredients that also function as polyphenols, antioxidants, sometimes as preservatives, and consequently giving food products its efficacious characteristics. Color plays a crucial role in determining the quality of a product as well as its acceptance. Regardless of their collective advantages like owing great color intensity, there are many factors like handling, storage, and processing conditions that influence their final hue which is sometimes not desirable. An overview of current literature on utilizable wall materials for natural colorants and a description of techniques for microencapsulating food colorants are provided in this paper. The retention of pigment for maximum bioavailability in the human gastrointestinal system through food supplementation requires adequate encapsulation strategies. The present review also discusses recent developments in traditionally used techniques that have been employed to maximize physicochemical characteristics of food. Additionally, the purpose of this review is to explore and examine some of the application of natural food colors in food industry. Practical application: To meet the ever‐increasing consumer demand for natural‐derived and safer food ingredients that lack any adverse effects and can even encourage good health, a number of experiments have been conducted for the development of more effective and selective food colorants that are consumer‐friendly. To equate their properties with synthetic ones, natural colorants must be optimized for processing conditions, research into new sources, and new formulations for stability must be done. This article reflects on one such strategy which is encapsulation. The purpose of this review is to elaborate on the usage of different techniques and applications in order to assess the stability, efficiency and commercial possibilities of encapsulated colorant and to summarize briefly the regulation administered by different authorities for standardization of these colorants. Therefore, it is strongly advised that rules and initiatives to educate consumers and food businesses concerning food colors be put into effect. Regulations, labeling requirements, and product developments make it difficult to navigate this rapidly changing dynamics of natural food colors. Therefore, substantial studies on each valid core and wall material provide immeasurable scope of study. Furthermore, the stabilization of natural pigments poses the greatest challenge to their use as food colors. This can only be overcome by extensive research that can make us familiar with all their implications. [ABSTRACT FROM AUTHOR]

Millet bran is rich in nutrients and bioactive components. Polyphenols play an important role as one of the active components, but their properties are not very stable and are prone to oxidative degradation under certain conditions. In this paper, we extracted polyphenols from millet bran by ultrasonic combined with DESs and prepared micro-capsules by embedding them to study their physicochemical properties. The results showed that the total polyphenol content of millet bran was 10.58 mg/g under the conditions of ultrasonic-assisted extraction for 30 min at 45 °C with a material-liquid ratio of 1:36 g/mL. After the microcapsules were prepared, the structure of millet bran polyphenol microcap-sules was analyzed by scanning electron microscopy, and it was found that the outer surface of the microcapsules was smooth and the particles were of uniform size. The infrared spectrum showed that the yeast cells had a good effect on the encapsulation of millet bran polyphenols; in the simulated gastric juice, the release of millet bran polyphenol microcapsules was faster than in the simulated intestinal juice, and the core material was released up to 96% within 2h, and the core material was basically released completely after 5 h. Microencapsulation increased the stability performance of millet bran polyphenols, and provided the theoretical basis for the deep development and utilization of millet bran. [ABSTRACT FROM AUTHOR]