Shell Thickness Research Articles

Rotordynamic analyses of stiffened cylindrical structures using high-fidelity shell models

The dynamic response of various rotating stiffened cylindrical and disk structures has been performed using low- and high-fidelity two-dimensional finite element models. The methodology is based on the Carrera Unified Formulation, in which the shell models are obtained hierarchically and automatically. These theories are formulated by expanding the unknown variables over the shell thickness. Various shell models can be implemented depending on the choice of the polynomial employed in the expansion. Lagrange polynomials are considered for developing different kinematic models and for easily modeling the stiffeners. The stiffener deformation is precisely captured through higher-order models, and the mechanical continuity between the stiffeners and skin is automatically guaranteed at the Lagrange points. The linearized equations of motion include the Coriolis and initial stress contributions. Stiffened cylinders and disks with different boundary conditions are considered. The results are compared with the three-dimensional finite element solutions from the literature or obtained using commercial software.

Study on the oxidation mechanism of micron- and nano-sized aluminum powders influenced by alumina shell

Thermal behaviors for aluminum particles at oxidative atmosphere gradually heating system were discussed. Heating micron- and nano-sized aluminum powders from room temperature to 1400℃ using thermal analysis method. The results showed that the reaction process for micron-sized aluminum particles can be divided into four stages which include the phase change of oxidized shell, increasing thickness of alumina shell, main broken shell oxidizing process and the phase change of alumina shell in high temperature. Thermal analysis for micro aluminum particles was carried out with shell thickness adjustments via ambient manual means. It turned out that the oxide layer thickness would have full limitation effects on the slow oxidation for micro aluminum particles with shell structure when it was increased above twice of the original thickness. The limitation effects of oxide shell thickness on the heating processes in gradually heating system were proposed. Humidity environment can make the thickness of alumina increase in a certain range when the particles are in nano-scale. Complete oxidation processes were observed but an increase of the oxidation temperature was identified.

Reaction mechanism of micron-sized aluminum powders in O2 and CO2 gradually heated environment

The behavior of aluminum powders in specific oxidized environment is different from each other obviously. Thermal behaviors of micron-sized aluminum powders in different oxygenated and gradually heating environments were discussed in order to find out the oxidation mechanism. Particular attention is paid to the reaction mechanism of oxygen and carbon dioxide atmosphere. Thermogravimetric analysis and related characterization methods are used and the results demonstrated that under the certain condition, reaction process of micron-sized aluminum powders can be divided into four stages. General routes for the oxidation of micron-sized aluminum in general heating system are the same, however, itis different among the extent of reaction at the third stage in different kinds of oxidizing gas atmospheres. Gas phased products were detected during the main reaction stage under carbon dioxide by combining thermal analysis and mass spectrometry which contributes to the rupture of alumina shell and further reaction of micron-sized aluminum powders. Consequently, rapider and more complete reaction process was achieved. The increasing thickness of original alumina shell can restrict the reaction rate of aluminum powders harder at the same time.

Studies on activity and oxide shell thickness of micron-sized Mg-Al alloy powder

The empirical formula of average oxide thickness of atomized micron-sized aluminum - magnesium alloy powder was proposed. At the same time, the influence of particle size and the ratio of magnesium on samples’ activity was studied. The phase composition, morphology, and oxidation process of the alloy powders were studied by x-ray diffraction, scanning electron microscope/energy-dispersive x-ray, respectively. Study on the change of powder activity was achieved by standard gas volumn method. The results show that the oxide thickness of the atomized micron-sized aluminum - magnesium alloy powder is positively correlated with the particle size, and the activity decreases with the increase of the particle size and the magnesium content.

Multiphysics simulation of magnetoelectric micro core-shells for wireless cellular stimulation therapy via magnetic temporal interference.

This paper presents an innovative approach to wireless cellular stimulation therapy through the design of a magnetoelectric (ME) microdevice. Traditional electrophysiological stimulation techniques for neural and deep brain stimulation face limitations due to their reliance on electronics, electrode arrays, or the complexity of magnetic induction. In contrast, the proposed ME microdevice offers a self-contained, controllable, battery-free, and electronics-free alternative, holding promise for targeted precise stimulation of biological cells and tissues. The designed microdevice integrates core shell ME materials with remote coils which applies magnetic temporal interference (MTI) signals, leading to the generation of a bipolar local electric stimulation current operating at low frequencies which is suitable for precise stimulation. The nonlinear property of the magnetostrictive core enables the demodulation of remotely applied high-frequency electromagnetic fields, resulting in a localized, tunable, and manipulatable electric potential on the piezoelectric shell surface. This potential, triggers electrical spikes in neural cells, facilitating stimulation. Rigorous computational simulations support this concept, highlighting a significantly high ME coupling factor generation of 550 V/m·Oe. The high ME coupling is primarily attributed to the operation of the device in its mechanical resonance modes. This achievement is the result of a carefully designed core shell structure operating at the MTI resonance frequencies, coupled with an optimal magnetic bias, and predetermined piezo shell thickness. These findings underscore the potential of the engineered ME core shell as a candidate for wireless and minimally invasive cellular stimulation therapy, characterized by high resolution and precision. These results open new avenues for injectable material structures capable of delivering effective cellular stimulation therapy, carrying implications across neuroscience medical devices, and regenerative medicine.

On the thermodynamic entropy in the microcanonical ensemble of classical systems

We demonstrate that the surface entropy given by the volume of an energy shell in the phase space can be the thermodynamically consistent entropy in a classical microcanonical ensemble if the thickness of the energy shell is not an arbitrary constant but a non-extensive function satisfying a specific differential equation. A particular form of the energy shell thickness as a possible solution to the differential equation converts the surface entropy into the volume entropy given by the phase-space volume bounded by a constant energy surface. However, such a form bears a problem: The temperature derived accordingly becomes extensive when the density of states is a non-monotonic function of energy. Based on the adiabatic invariance of the degeneracy of a quantum system and the Weyl correspondence, we propose an alternative solution: the energy shell thickness given by the energy level spacing in the quantum counterpart of the classical ensemble considered, which is illustrated by a few simple examples.

Numerical simulation of heat transfer during meat ball cooking and microbial food safety enhancement.

This study was conducted to apply the finite volume method (FVM) to solve the partial differential equation (PDE) governing the heat transfer process during meat cooking with convective surface conditions. For a one-dimensional, round-shaped food, such as meat balls, the domain may be divided into shells of equal thickness, with energy balance established for each adjacent shell using in the finite difference scheme (FDS) to construct a set of finite difference equations, which were then solved simultaneously using the FORTRAN language and the IVPAG subroutine of the International Mathematics and Statistics Library. The FDS is flexible for temperature-dependent physical properties of foods, such as thermal conductivity (k), specific heat (Cp ), thermal diffusivity (α), and boundary conditions, for example, surface heat transfer coefficient (h), to predict the dynamic temperature profiles in beef and chicken meat balls cooked in an oven. Once the FVM model was established and validated, it was used to simulate the dynamic temperature profiles during cooking, which were then used in combination with the general method to evaluate the thermal lethality of Shiga toxin-producing Escherichia coli and Salmonella spp. using D and z values in ground meats during cooking. The method can be applied to design cooking processes that effectively inactivate foodborne pathogens while maintaining the quality of cooked meats and evaluate the adequacy of a cooking process. PRACTICAL APPLICATION: The temperature dependences of thermal conductivity (k) and thermal diffusivity (α) of raw ground beef and ground chicken meats were measured. These thermal properties were then used in numerical simulation to predict the dynamic heating temperature profile and thermal lethality of ground beef and chicken meat balls. The numerical simulation method may be used to optimize and evaluate thermal processes and ensure the inactivation of pathogens in meat products during cooking.

Enhanced electrochemical behavior of C@CdS Core-Shell heterostructures

The current work presents hydrothermally synthesized carbon@cadmium sulfide core–shell nanostructures with varying carbon nanosphere concentrations. The series is prepared to investigate the shell thickness depending on the concentration of precursors and consequently impacting the optical and electrochemical properties of the core–shell structures. XRD analysis reveals enhanced crystallinity with reduced carbon. SEM & TEM confirm uniform spherical core–shell structures, with optimal uniformity at lower carbon levels. UV–vis spectroscopy demonstrates visible range absorption and reduced band gap with decreased carbon. Electrochemical analysis exhibits diffusion-controlled behavior and Warburg impedance, making the low-carbon sample most suitable for solar cells. Core-shell structures outperform pure carbon samples in absorbance and impedance spectroscopy, showcasing potential for solar cell applications.

Three-dimensionally printable hollow silica nanoparticles for subambient passive cooling

Abstract Solar reflectance and thermal emissivity are critical benchmarks for evaluating the effectiveness of passive cooling strategies. The integration of three-dimensional (3D) printing techniques with passive cooling materials enables local thermal management of multifaceted objects, offering opportunities for unexplored energy-saving applications. For example, conformal printing of cooling materials can mitigate solar absorption caused by the top metal electrodes in solar cells, thereby improving their efficiency and lifetime. In this study, we report the synthesis of 3D printable hollow silica nanoparticles (HSNPs) designed to induce subambient cooling performance under daylight conditions. HSNPs with diameters of 400–700 nm and silica shell thicknesses of approximately 100 nm were synthesized using an in-situ sol–gel emulsion method. Subsequently, these HSNPs were formulated into printable pastes by carefully selecting the mixture concentration and molecular weight of polyvinylpyrrolidone (PVP). The PVP-linked HSNPs exhibited a solar (0.3–2.5 μm) reflectivity of 0.98 and a thermal (8–13 μm) emissivity of 0.93. In contrast to a single silica nanoparticle (NP), the scattering analysis of a single HSNP revealed a distinctive scattering distribution characterized by amplified backward scattering and suppressed forward scattering. In outdoor daytime experiments, the HSNP-printed sample led to the subambient cooling of a dielectric substrate, surpassing the cooling performance of reference materials such as silica NPs, silver pastes, and commercial white plastics and paints.

The Utilization of Candlenut Shell-Based Activated Charcoal as the Electrode of Capacitive Deionization (CDI) for Seawater Desalination

Activated carbon or activated charcoal is one of the best materials that can be used as a constituent of CDI electrodes, not only because of its various advantageous properties but also because it can be sourced abundantly from plant waste. This research aims to determine the effect of the thickness of the candlenut shell activated charcoal electrode and the particle size of the activated carbon used on the capacitive deionization (CDI) performance in seawater desalination. Candlenut shell-based activated charcoal is obtained in three stages, namely preparation, carbonization, and activation. The carbonization stage was done by using a pyrolysis reactor at a temperature of 400°C for 8 hours. The activation was done with the activator of H3PO4 67%. The variation of thickness was 6 mm, 8 mm, 10 mm, and 15 mm while the variation of particle size was 60 mesh, 80 mesh, 100 mesh, and 200 mesh. The results showed that the higher capacitance was obtained with the thinner electrodes, where the best value was the thinnest electrode, 6 mm, which produced the highest capacitance, 122.96 nF. For the desalination of seawater, it is shown that the finest particle/smallest particle size will result in the best desalination performance, where 200 mesh particle size will result in the decrease of salinity from 34% to 4%. That is 88.23% decrease in salinity. Therefore, the using of candlenut shell-based activated carbon as the electrode in CDI is proven to be able to obtain good performance in seawater desalination.

Exploring the interplay of LSPR and CT: Hierarchical shell thickness optimization for advanced SERS sensing using AgNW@ZIF-8 Core@Shell substrates

Synergistic surface-enhanced Raman spectroscopy (SERS) substrates, leveraging the combined strengths of electromagnetic enhancement (EM) and chemical enhancement (CM), have been extensively explored in the literature. In this study, we introduce a distinctive approach to fabricating core@shell structures, specifically employing silver nanowire @ zeolite imidazole framework-8 (AgNW@ZIF-8) as synergistic SERS substrates. Notably, these substrates offer meticulous control over shell thickness through a straightforward post-synthesis procedure. Utilizing Ag nanowires as the plasmonic core, selected for their broader localized surface plasmon resonance (LSPR) absorption range compared to nanoparticles, we encapsulate them within ZIF-8, a metal-organic framework (MOF) recognized for its proficient charge transfer (CT) properties. Our investigation encompasses the SERS performance across various Raman-active molecules, considering their diverse sizes and distinct frontier molecular orbitals (FMO) energy levels. Additionally, we systematically explore the influence of alterations in shell thickness on SERS outcomes and scrutinize the impact of probe orientation. This comprehensive study not only advances the understanding of synergistic effects intrinsic to MOFs-metal SERS substrates but also provides valuable insights for the rational design of highly sensitive substrates tailored for practical applications.

Quantitative Analysis of the Impacts of Ash from Lubricating Oil on the Nanostructure of Diesel Particulate Matter

Microscopic analyses of the effects of ash on particulate matter oxidation are rather scarce. In this study, three different lubricating oils with varying ash contents were used to investigate their effects on the nanostructure of diesel particulate matter. The nanostructure and nanostructure parameters, including fringe length, fringe separation distance, and fringe tortuosity, were studied using high-resolution transmission electron microscopy. The results show that all samples obtained from blending with different lubricant oil present typical core–shell structures. The inner cores remain relatively unchanged, whereas the thickness of the outer shells increases with the increasing ash content in the lubricant oil under the same working conditions. The fringe length increases and the fringe separation distance decreases with the rising ash content in the lubricant oil operating in the same working conditions. The fringe tortuosity decreases when the ash content in the lubricant oil increases from 0.92% to 1.21%, but shows little change when the ash content in the lubricant oil increases from 1.21% to 1.92%. Based on the effects of ash on the nanostructure parameters, it can be inferred that the oxidation activity of particles decreases with increasing ash content in the lubricant oil.

Investigation of Solidification Heat Transfer in Slab Continuous Casting Process Based on Different Roll Contact Calculation Methods.

The heat transfer of a slab is significantly influenced by roll contact during the continuous casting process. The influence of roll contact calculation methods on the predicted heat transfer results has not been previously investigated. In this work, the non-uniform solidification of the wide-thick slab was studied with a 2D heat transfer model using real roll contact method (R. method) and equivalent roll contact method (E. method). The predicted slab surface temperature and shell thickness were verified with the measured results of the infrared camera and nail shooting experiments, respectively. Then, the predicted heat transfer results (including the slab surface temperature, mushy region length, and solidification end position) for the wide-thick slab with different thicknesses and different casting speeds were calculated using the E. method and R. method, and the influence of these two roll contact methods on the predicted heat transfer results was discussed for the first time. The results show that both these two roll contact methods could be applied to accurately predict the slab surface temperature without considering the transient temperature dips in the roll-slab contact regions. However, the deviation of the predicted mushy region length and solidification end position using the E. method are obvious. Compared with the R. method, the predicted mushy region length obtained using the E. method is larger and the solidification end obviously subsequently moves along the casting direction.

Fabrication of an Optoplasmonic Raft with Improved SERS Performance Detecting Methamphetamine through Bubble Enrichment.

In this work, a novel raft-like structure that combines noble metal nanoparticles (NPs) with an interconnected layer of hemispherical dielectric shell was fabricated and characterized. It was discovered that this hybrid material can enhance the optoplasmonic interaction between plasmonic and dielectric components, thereby improving the sensing performance in surface-enhanced Raman spectroscopy (SERS). Varied geometric parameters of the fabricated optoplasmonic raft, including the inner diameter and thickness of the dielectric shell, were attempted and analyzed through numerical simulation and experimental SERS measurements. With particular size, thickness, and incident orientation, the silica shell focuses the incident optical flow into the deposited silver NPs, undergoing similar near-field focusing behavior in comparison with other optoplasmonic entities. This optoplasmonic raft floating on the water surface is able to harvest the target molecules effectively through bubble enrichment, which rapidly captures and concentrates analytes from the aqueous phase. With a limited sampling time, the sensing performance of the developed optoplasmonic raft is improved by applying the optimized parameters involved in bubble enrichment. The substrates and corresponding enrichment method were implemented in the detection of methamphetamine (METH), achieving a limit of detection (LOD) down to 0.035 nM. As for practical onsite detection, the developed substrate and bubbling strategy were applied in an assembled set, employing a portable Raman spectrometer and an air pump. This set is able to detect METH dissolved in regular commercial beer, which is quite competent in the investigation of drug abuse.

Large deflection response of functionally graded porous structures considering geometrical nonlinearity using an improved FSDT

This study’s objective is to propose a full 3D finite element modeling for examining the geometrically nonlinear (NL) response of functionally graded (FG) porous materials with plates, ring, and cylindrical shapes. An improved first-order shear deformation theory (IFSDT) is utilized in order to develop the 3D solid-shell element. The governing equations are developed in a way that offers a parabolic distribution of the transverse shear strains through the FG porous shell thickness and a zero condition of the transverse shear stresses on the top and bottom surfaces. The given IFSDT solid-shell element has the ability to model any kind of shell structures and incorporates a 3D material law. In this study, two types of porosity distribution functions are considered. The effectiveness of the present IFSDT solid-shell element is demonstrated through linear (L) and NL numerical examples. The effect of the porosity distribution, porosity coefficient, power-law index, geometrical design parameters, and boundary conditions on the geometrically NL response of FG porous shells structures is evaluated.

Effects of different levels of iron, iodine and vitamin B12supplementation on egg quality and antioxidant capacity of eggs at different times of storage in laying hens

The experiment was carried out to evaluate the effects of adding different levels of iron salts, iodine and vitamin B12 on yield, quality traits and antioxidant capacity of eggs in laying hens. A total of 320 laying hens (HyLine Variety White, 28 wk old) in a 2x2x2 factorial experiment were randomly assigned to 8 groups, and each group consisting of 40 hens (5 replicates of 8 hens each) for a period of approximately 13 weeks in a completely randomized design. Hens in the control group received a basal diet with no supplementation whereas hens in treat 2 received basal diet supplemented with 400 mg Fe/kg as FeSO4, treat 3 (basal diet + 450 mg I/kg as KI), treat 4 (basal diet + 0.1 mg B12vit/kg), treat 5 (basal diet + 400 mg Fe/kg as FeSO4 + 450 mg I/kg as KI), treat 6 (basal diet + 400 mg Fe/kg as FeSO4 + 0.1 mg B12Vit/kg), treat 7 (basal diet + 450 mg I/kg as KI + 0.1 mg B12Vit/kg), treat 8 (basal diet + 400 mg Fe/kg as FeSO4 + 450 mg I/kg as KI + 0.1 mg B12Vit/kg), respectively. The results showed that the use of iodine and vitamin B12 increased the shell thickness of eggs (P<0.05). The use of iron, iodine and vitamin B12 supplements increased the antioxidant capacity of eggs compared to the control group (P<0.05). The highest antioxidant capacity of eggs (0.77) was observed when these three supplements were used together in the diet of laying hens. The length of storage had significant effects on the weight of albumin and yolk and antioxidant content of eggs (P<0.05). The highest weight of albumin and antioxidant content was at the beginning of storage, while the highest weight of yolk was obtained in 4 weeks after storage, with increasing of storage time to 8 weeks, all three attributes of albumin weight, yolk weight and antioxidant content of eggs decreased (P<0.05). The related effects of interval of the storage and the experimental supplementation, the use of iron, iodine and vitamin B12 supplements increased the antioxidant capacity of eggs, so that the highest amount of antioxidants in eggs in 8 weeks after storage and by supplementing the diets with all three additives (P<0.05). According to the present experiment, the use of iron, iodine and vitamin B12 additives in the diet of laying hens, improves the performance, the content of iron and iodine elements in eggs and maintains the suitable condition of eggs during storage.

Surface Cross-Linking by Macromolecular Tethers Enhances Virus-like Particles' Resilience to Mucosal Stress Factors.

Virus-like particles (VLPs) are emerging as nanoscaffolds in a variety of biomedical applications including delivery of vaccine antigens and cargo such as mRNA to mucosal surfaces. These soft, colloidal, and proteinaceous structures (capsids) are nevertheless susceptible to mucosal environmental stress factors. We cross-linked multiple capsid surface amino acid residues using homobifunctional polyethylene glycol tethers to improve the persistence and survival of the capsid to model mucosal stressors. Surface cross-linking enhanced the stability of VLPs assembled from Acinetobacter phage AP205 coat proteins in low pH (down to pH 4.0) and high protease concentration conditions (namely, in pig and mouse gastric fluids). Additionally, it increased the stiffness of VLPs under local mechanical indentation applied using an atomic force microscopy cantilever tip. Small angle X-ray scattering revealed an increase in capsid diameter after cross-linking and an increase in capsid shell thickness with the length of the PEG cross-linkers. Moreover, surface cross-linking had no effect on the VLPs' mucus translocation and accumulation on the epithelium of in vitro 3D human nasal epithelial tissues with mucociliary clearance. Finally, it did not compromise VLPs' function as vaccines in mouse subcutaneous vaccination models. Compared to PEGylation without cross-linking, the stiffness of surface cross-linked VLPs were higher for the same length of the PEG molecule, and also the lifetimes of surface cross-linked VLPs were longer in the gastric fluids. Surface cross-linking using macromolecular tethers, but not simple conjugation of these molecules, thus offers a viable means to enhance the resilience and survival of VLPs for mucosal applications.

A normal tracking differential confocal measurement method for multiple geometric parameters of hemispherical shell resonator with a common reference

This paper proposes a normal tracking differential confocal measurement method for the inside and outside surface profiles, shell thickness uniformity, and central asymmetry of inside and outside surfaces of the hemispherical shell resonator (HSR). A differential confocal technique with high-transmittance focusing ability is used to measure a single point on the inside and outside surfaces of the HSR. The normal alignment measurement technique is used to accurately measure the inside and outside surfaces and shell thickness of the HSR with a common reference in one measurement process. The HSR is step-rotated to synchronously collect information on the inside and outside surfaces, and using the differential confocal sensor to measure the different normal-section profiles. The experimental results indicate successful measurement of HSR central asymmetry. The repeated measurement accuracy for the inside and outside surface profiles and thickness uniformity is better than 30 nm.

Comparative Study of Egg Quality Traits of Sasso Chicken Breed under Different Management Systems and Phenotypic Correlation of Egg Parameters in Ethiopia

This study was conducted to evaluate the egg quality traits of Sasso chicken breed under different managements. For the experiment 160 fresh eggs form differently managed Sasso chickens (100 from on-station and 60 from on-farm) were randomly taken. The fresh eggs collected from farmers in Yirgalem were brought to Hawassa University poultry farm for quality measurement and the eggs collected from poultry farm of College of Agriculture in Hawassa University were separately determined. The recorded data was analyzed using SAS (ver. 9.4). Management system difference has a significant influence on more than half of studied external traits such as egg weight, egg length, egg width, shell thickness and egg surface area. The Sasso chickens managed under intensive system had significantly (p<0.05) higher mean egg weight (59.0g), egg length (57.5mm), egg width (42.2mm) and egg surface area (84.7mm2) than the same chicken breed reared under farmers management system. There was a significant difference in albumen weight, albumen height, yolk height, albumen ratio, yolk index, yolk albumen ratio and Hough unit for the eggs collected from the Sasso chickens under different management system. Egg weight has a highly significant and strong positive (p<.0001) phenotypic correlation with egg surface area (0.99), egg length (0.65), egg width (0.72) and shell weight (0.52). Albumen weight has significant correlation with all the studied internal egg quality parameters. It has the negative correlation with yolk ratio (-0.14) and yolk albumen ratio (-0.69). There was a variation for egg quality traits of Sasso chicken in different management systems where the on-station management system is better.

Differential effects of ocean warming and BDE-47 on mussels with various personalities

Marine warming and polybrominated diphenyl ethers (PBDEs) pollution are two of the most concerning environmental problems in recent years. However, the impact of their co-occurrence on marine bivalves and the tolerance of bivalves with different traits remain unknown. In this study, thick shell mussels Mytilus coruscus were divided into two personalities according to individual feeding and byssus growth. The reliability of the classification was validated by respiration, self-organization, and post-stress behavior. Then, the survival rate, hemolymph immunity, and digestive glands oxidase activity of classified mussels were evaluated after 21 days of compound exposure to warming and BDE-47. The results showed that mussels could be divided into proactive and reactive types consistently. Compared to reactive mussels, proactive mussels exhibited some traits, such as faster food recovery, more byssus growth, higher metabolic rate, and more efficient clustering. Both single or combined warming and BDE-47 exposure impacted the individual survival, hemolymph, and antioxidase of mussels. Notably, the negative impacts of BDE-47 were exacerbated by warming. Moreover, proactive mussels displayed better adaptability with higher survival rates along with less damage to hemolymph immunity and antioxidant ability compared to reactive ones when facing environmental challenges. This study highlights potential risks associated with the coexistence of marine warming and PBDEs pollution while demonstrating differential fitness among individuals with distinct personalities.