Shell System Research Articles

A Layered-Shell Model of Anisotropic Composites: Extension of the Milgrom and Shtrikman Model

In this work, the extension of the Milgrom and Shtrikman model to anisotropic composite materials containing n-layered hollow ellipsoidal inclusions, is presented. The effective properties of such materials are determined using the Green function techniques and interfacial operators. Here, the basic unit of the microstructure is a hollow system of contacting concentric ellipsoidal shells, each of which is made of one of the components. Space is packed with such units of different sizes, but the same proportions; the cavity within each such shell system is then packed with similar systems and this continues in an infinite nesting sequence. In the final configuration, the effective properties are inside and outside the basic unit of layered shells (n+1). For n=2 and in the case of isotropic material, it is shown that the effective compressibility covers all ranges of the Hashin-Strikman bounds.

Controlled enzyme cargo loading in engineered bacterial microcompartment shells.

Bacterial microcompartments (BMCs) are nanometer-scale organelles with a protein-based shell that serve to co-localize and encapsulate metabolic enzymes. They may provide a range of benefits to improve pathway catalysis, including substrate channeling and selective permeability. Several groups are working toward using BMC shells as a platform for enhancing engineered metabolic pathways. The microcompartment shell of Haliangium ochraceum (HO) has emerged as a versatile and modular shell system that can be expressed and assembled outside its native host and with non-native cargo. Further, the HO shell has been modified to use the engineered protein conjugation system SpyCatcher-SpyTag for non-native cargo loading. Here, we used a model enzyme, triose phosphate isomerase (Tpi), to study non-native cargo loading into four HO shell variants and begin to understand maximal shell loading levels. We also measured activity of Tpi encapsulated in the HO shell variants and found that activity was determined by the amount of cargo loaded and was not strongly impacted by the predicted permeability of the shell variant to large molecules. All shell variants tested could be used to generate active, Tpi-loaded versions, but the simplest variants assembled most robustly. We propose that the simple variant is the most promising for continued development as a metabolic engineering platform.

Melting performance of PCM with MoS2 and Fe3O4 nanoparticles using leaf-based fins with different orientations in a shell and tube-based TES system

Phase change materials (PCMs) are frequently utilized in the thermal sector, especially for thermal energy storage (TES) applications. The purpose of this study was to analyze the thermal efficiency and melting characteristics of a leaf-vein-shaped fin in a triplex tube heat exchanger. The analysis focused on the use of pure molten salt PCM and a combination of molten salt PCM with MoS2 and Fe3O4 nanoparticles. The study utilized ANSYS Fluent software to conduct numerical simulations and analyze seven distinct fin arrangements. The simulations were employed to visualize and examine the liquid fraction, temperature, and fluid velocity. The findings indicated that the leaf-vein fin shape greatly improved the dispersion of liquid fraction, average temperature, and velocity in comparison to alternative fin designs. The addition of MoS2 and Fe3O4 nanoparticles significantly enhanced the melting and thermal characteristics of the PCM as a result of heightened thermal conductivity. This showcases the capability of the leaf-vein fin design and PCM nanocomposites to enhance the efficiency of thermal energy storage in triplex tube systems. About 2500 s PCM melt about 36% for case A, but melting rate enhance up-to 55% using nano particles. Melting rate enhance 91% in 1000 s in case of G using 8 fins as compare to case A having no fins.

Semi-analytical vibration modeling of complex axisymmetric shells using shifted Legendre series

This paper presents a semi-analytical approach based on the shifted Legendre series for vibration modeling of complex axisymmetric shells. This method divides the structure along its generator into complex axisymmetric shells comprised solely of conical and spherical shell segments. A global cylindrical coordinate system is established to unify the coordinate system of complex axisymmetric shells. Coupling between segments and the simulation of arbitrary boundary conditions are achieved using artificial spring technology. Based on the first-order shear deformation theory (FSDT), the energy functional of each segment is derived. The circumferential displacement is expanded using Fourier series, while the meridional displacement is expanded using the shifted Legendre series at shifted Gauss-Lobatto nodes. Utilizing the inner product matrix and differential matrix of the shifted Legendre series, the integration and differentiation processes in the vibration characteristic equation are simplified into a product form, significantly enhancing computational efficiency. Through convergence analysis and comparison of the computational results of the present method with numerical simulation results, experimental results and literature results demonstrate the advantages of high convergence, high accuracy and fast solution speed of this solution method. On this basis, the vibration characteristics of ring-stiffened double-layer hemispherical shells are investigated. The results demonstrate the great applicability of this method for vibration modeling of complex axisymmetric shells in engineering.

Reflectivity and Angular Anisotropy of Liquid Crystal Microcapsules with Different Particle Sizes by Complex Coalescence.

Cholesteric liquid crystal microcapsules (CLCMs) are used to improve the stability of liquid crystals while ensuring their stimulus response performance and versatility, with representative applications such as sensing, anticounterfeiting, and smart fabrics. However, the reflectivity and angular anisotropy decrease because of the anchoring effect of the polymer shell matrix, and the influence of particle size on this has not been thoroughly studied. In this study, the effect of synthesis technology on microcapsule particle size was investigated using a complex coalescence method, and the effect of particle size on the reflectivity and angular anisotropy of CLCMs was investigated in detail. A particle size of approximately 66 µm with polyvinyl alcohol (PVA, 1:1) exhibited a relative reflectivity of 16.6% and a bandwidth of 20 nm, as well as a narrow particle size distribution of 22 µm. The thermosetting of microcapsules coated with PVA was adjusted and systematically investigated by controlling the mass ratio. The optimized mass ratio of microcapsules (66 µm) to PVA was 2:1, increasing the relative reflectivity from 16.6% (1:1) to 32.0% (2:1) because of both the higher CLCM content and the matching between the birefringence of the gelatin-arabic shell system and PVA. Furthermore, color based on Bragg reflections was observed in the CLCM-coated ortho-axis and blue-shifted off-axis, and this change was correlated with the CLCM particle size. Such materials are promising for anticounterfeiting and color-based applications with bright colors and angular anisotropy in reflection.

Vibration damping method of cantilever structure considering redundant constraint of monocrystalline blade casting mold shell

Excessive vibrations of the mold shell during the manufacturing process of monocrystalline blades lead to dendirite and frekle defects in directional solidification. The dynamics of the casting lifting device-mold shell system is analysed theoretically to reveal the influence of key parameters such as excitation force, damping and stiffness on the monocrystalline blade casting. The effect of redundant constraint onto the system is analysed via the developed vibration model. A lifting device-mold shell system test bench is developed, a slide-support arm device is designed to provide redundant constraint. A self-developed high-precision sensor is used to test the vibration signals, and the effectiveness of the damping method is verified. The experimental results show that the redundant constraint can reduce the undesired vibration of mold shell by more than 77 %, which ensures the casting quality of monocrystalline blades. The proposed vibration damping method can provide a reference for the vibration damping of the cantilever machine.

Developing a magnetite/mesoporous silica core /shell system for enhancing the anti-cancer performance of Doxorubicin at low doses for breast cancer treatment

Developing a magnetite/mesoporous silica core /shell system for enhancing the anti-cancer performance of Doxorubicin at low doses for breast cancer treatment

Impact of Eccentric Tube Shapes and Heat Pipes on Phase Change Material’s Thermal Charging

The thermal charging performance of phase change material (PCM) in an eccentric tube and shell system is investigated through numerical analysis. Various shapes of eccentric tubes, including circular, semi-circular, triangular, inverted triangular, square, and C-shape, are considered. The PCM mass and shell diameter remain consistent across all tube geometries. Moreover, vertical heat pipes (HPs) are utilized to connect the heat source eccentric tube wall and the PCM stored in the shell. The examination evaluates the consequences of the tube shape and HPs using liquid fraction, temperature time history and contours, enhancement ratio, total energy storage, and mean power as performance indicators. The findings demonstrate that non-circular cases exhibit a shorter melting time than circular tube cases. The C-shape tube has the (Largest) 30.3% less thermal charging time than the circular tube, and the mean power is 39% higher. Moreover, adding HPs increases the mean power by up to 241% more than the circular tube, and reduces thermal charging time by about 72.2%. The inverted triangular tube exhibits the highest energy charge capability within the selected options.

Hepatitis B Virus Neutralization with DNA Origami Nanoshells.

We demonstrate the use of DNA origami to create virus-trapping nanoshells that efficiently neutralize hepatitis B virus (HBV) in cell culture. By modification of the shells with a synthetic monoclonal antibody that binds to the HBV envelope, the effective neutralization potency per antibody is increased by approximately 100 times compared to using free antibodies. The improvements in neutralizing the virus are attributed to two factors: first, the shells act as a physical barrier that blocks the virus from interacting with host cells; second, the multivalent binding of the antibodies inside the shells lead to stronger attachment to the trapped virus, a phenomenon known as avidity. Pre-incubation of shells with HBV and simultaneous addition of both components separately to cells lead to comparable levels of neutralization, indicating rapid trapping of the virions by the shells. Our study highlights the potential of the DNA shell system to rationally create antivirals using components that, when used individually, show little to no antiviral effectiveness.

Heat absorption/release efficiency betterment of phase change material inside a shell-and-tube latent heat storage system under six different conditions of tube and fins

Researchers are exploring innovative solutions for thermal energy storage to address the challenges posed by intermittent renewable sources, enhance energy efficiency, and contribute to the global shift towards cleaner and more sustainable energy practices. In the pursuit of an optimal system to improve the heat release/absorption efficiency of phase change materials (PCMs), a unique shell and tube latent heat storage system with four rectangular fins was designed. The melting and solidification behaviors of the material in this device were examined by manipulating the tube's position within the shell and fins around the tube. Six different cases were considered such as case A (tube in the center of the shell), case B (tube at the top of the shell), case C (tube at the bottom of the shell), case D (tube in the center of the shell with fins on its sides), case E (tube at the top of the shell with fins located in its bottom section), and case F (tube at the bottom of the shell with fins located in its top section). Cases D and E were the best options for absorbing and releasing heat in the shortest time. However, it should be noted that case F was faster during the melting process and dropped behind in the final stages. The authors proposed that if achieving a balanced result without incurring additional costs is essential, case D is a suitable option since it offers reasonable performance in melting and solidification processes. However, suppose researchers and developers of energy storage systems are seeking higher performances where heat absorption and release occur much more rapidly. In that case, it is suggested to construct one of the cases, E or F, and implement a rotational mechanism to enable access to the other case. Based on the outcomes, cases D and F needed 6235 s and 7552 s, respectively, to fully melt. While all cases even required more than 3 h to solidify 80 % of the PCM. The complete melting speed of Case F is 21.12 % faster than that of Case D. Additionally, the time required for 50 % solidification is 14.79 % faster for Case E compared to Case D. During 3 h, this system could absorb 1172 kJ of energy (cases D and F) and release 893 kJ of energy (cases D and E).

Integrated System of Semi-submersible Offshore Wind Turbine Foundation and Porous Shells

A novel semi-submersible platform is proposed for 5 MW wind turbines. This concept focuses on an integrated system formed by combining porous shells with a semi-submersible platform. A coupled aerodynamic–hydrodynamic–mooring analysis of the new system is performed. The motion responses of the novel platform system and the traditional platform are compared. The differences in hydrodynamic performance between the two platforms are also evaluated. The influence of the geometric parameters (porosity, diameter, and wall thickness) of porous shells on the motion response behavior of the new system is studied. Overall, the new semi-submersible platform exhibits superior stability in terms of pitch and heave degrees of freedom, demonstrating minimal effects on the motion response in the surge degree of freedom.

Numerical simulation of a thermal energy storage system using sunrise and sunset transient temperature models

The temperature of the sun was modeled in this study using two transient solar temperature equations for sunrise and sunset that were developed for designing a latent heat thermal energy storage (LHTES) system for a concentrated solar power (CSP) plant. The derivation of the equations was based on the existing solar hour angle and the fundamental periodic function equations. Ansys' computational fluid dynamics code was used to investigate numerically the transient response of the conjugate melting and solidification of a phase change material (PCM) in a cylindrical shell and helical heat pipe (HHP) thermal system. The models for both equations were applied as user-defined functions (UDFs). The heat transfer medium was air. The predicted liquid and solid fractions provide quantitative data on the temperature and the stored solar energy. The effectiveness of both models in enhancing heat transfer and their suitability as real-time transient solar temperature models in heat transfer engineering is demonstrated by comparisons between their outputs. With high agreement, experimental data from the open literature was used to validate the numerical model's predictions. The solar temperature models aim to contribute to heat transfer enhancement for a reduced PCM energy storage time in designing a high-temperature solar thermal storage that is adequate to maintain a steady supply of electricity and energy for domestic and commercial applications and to accelerate the global transition to low-carbon energy.

Theoretical study of PdNi and PdCu clusters embedded on graphene modified by monovacancy and nitrogen doping.

The stability and reactivity of Pd4Ni4 and Pd4Cu4 clusters embedded on graphene modified by monovacancy and nitrogen doping were investigated using auxiliary density functional theory (ADFT) calculations. The most stable structure of the Pd4Ni4 cluster is found in high spin multiplicity, whereas the lowest stable energy structure of the Pd4Cu4 cluster is a close shell system. The interaction energies between the bimetallic clusters and the defective graphene systems are significantly higher than those reported in the literature for the Pd-based clusters deposited on pristine graphene. It is observed that the composites studied present a HOMO-LUMO gap less than 1 eV, which suggests that they may present a good chemical reactivity. Therefore, from the results obtained in this work it can be inferred that the single vacancy graphene and pyridinic N-doped graphene are potentially good support materials for Pd-based clusters.

Study on the flexural behaviour of the concrete filled square steel tube beam with the basic magnesium sulfate cement-based composite shell system

A new type of stay-in-place formwork (SIPF) concrete beam was proposed; this beam consists of a U-shaped shell made of basic magnesium sulfate cement-based composite (BMSCC), a perforated square steel pipe and core concrete. The prefabricated shell and square steel pipe form a composite SIPF, the steel pipe replaces the longitudinal reinforcement and hoop reinforcement, and the combination beam can be formed after pouring the core concrete inside. Four-point bending tests of two SIPF beams and one reinforced concrete (RC) comparison beam were conducted using longitudinal steel consumption as a parameter. The results showed that the SIPF beams exhibited a typical ductile damage pattern and that the precast shell was reliably bonded to the core concrete without spalling. The cracking load was increased by 198.25 %, the yield load by 66.3 %, and the ultimate load by 64.7 % for the same amount of steel used in the steel pipe instead of the reinforcing cage. After the equivalent longitudinal reinforcement rate of 1 % at the bottom of the SIPF beam was increased to 1.25 %, the flexural capacity increased by 9.65 %. By introducing the restraining stress coefficient and stiffness contribution coefficient, a formula for calculating the flexural capacity of the positive section of the SIPF beam was established.

Thermal performance enhancement of multiple tubes latent heat thermal energy storage system using sinusoidal wavy fins and tubes geometry modification

In this paper, performance enhancement of a shell and multiple tube latent heat thermal energy storage system (LHTESS) is numerically investigated by implementing sinusoidal wavy fins and different geometrical designs of heat transfer tubes. The annular space of the shell is filled with the paraffin wax RT35 as phase change material (PCM) and absorbs heat from hot water through the multiple tubes. With the constant total cross-section area of all tubes and fins as the constraint condition, the effect of tube number and tube shape incorporated with the proposed fins on the heat transfer properties of PCM during the melting process is evaluated. The computational results demonstrate that the sinusoidal wavy fins can improve the phase change efficiency compared to the conventional straight fins. The double-pitch sinusoidal wavy fins decrease the total melting time by 9.5% compared to the straight fins for the single-tube case. As the number of HTF tubes increased from one to four, the complete PCM melting time decreased by 38.3%. Geometrical design alterations of heat transfer tubes from circular to petal-shaped are proposed to further improve the thermal performance of multiple tubes LHTESS. The melting rate of PCM is accelerated with an increase in the number of petals. The petal tubes with nine petals can save the charging time up to 24 % in comparison with the circular tubes in a four-tube case with double-pitch sinusoidal wavy fins, and up to 57% compared to the base case with a single circular HTF tube and straight fins.

Does the openness of the Boundary Shell system influence the sustainable development of the high-tech industry?

High-technology industries have gained substantial recognition as pivotal drivers of economic growth and technological advancement in modern society. The imperative of sustainable development in high-tech industries cannot be overemphasized, as it plays a crucial role in enabling long-term growth, fostering innovation, and assuming environmental responsibility. This article presents a study on sustainable development in high-tech industries using Boundary Shell theory. The study investigates the role of the stable and sustainable entropy criterion for the Boundary Shell system of high-tech industries from an entropy balance perspective. It analyzes the upper and lower limits of the Boundary Shell support force. Additionally, it improves the traditional boundary system ratio model to comprehensively and objectively evaluate the sustainable development of high-tech industries. The results illustrate that the Boundary Shell of industrial innovation is stronger than that of external dependency, with a reversed ranking of internal evaluation factor strengths compared to the traditional model. This research integrates reaction-diffusion equations theory with entropy balance equations theory to address sustainability issues in the high-tech industry. We further analyze the sustainable development of the high-tech industry through a Boundary Shell theory perspective to advance sustainability in high-tech industries. Moreover, it provides useful insights into the sustainable development of high-tech industries.

Tubule system of earliest shells as a defense against increasing microbial attacks

The evolutionary mechanism behind the early Cambrian animal skeletonization was a complex and multifaceted process involving environmental, ecological, and biological factors. Predation pressure, oxygenation, and seawater chemistry change have frequently been proposed as the main drivers of this biological innovation, yet the selection pressures from microorganisms have been largely overlooked. Here we present evidence that calcareous shells of the earliest mollusks from the basal Cambrian (Fortunian Age, ca. 539-529 million years ago) of Mongolia developed advanced tubule systems that evolved primarily as a defensive strategy against extensive microbial attacks within a microbe-dominated marine ecosystem. These high-density tubules, comprising approximately 35% of shell volume, enable nascent mineralized mollusks to cope with increasing microbial bioerosion caused by boring endolithic cyanobacteria, and hence represent an innovation in shell calcification. Our finding demonstrates that enhanced microboring pressures played a significant role in shaping the calcification of the earliest mineralized mollusks during the Cambrian Explosion.

Towards using bacterial microcompartments as a platform for spatial metabolic engineering in the industrially important and metabolically versatile Zymomonas mobilis.

Advances in synthetic biology have enabled the incorporation of novel biochemical pathways for the production of high-value products into industrially important bacterial hosts. However, attempts to redirect metabolic fluxes towards desired products often lead to the buildup of toxic or undesirable intermediates or, more generally, unwanted metabolic cross-talk. The use of shells derived from self-assembling protein-based prokaryotic organelles, referred to as bacterial microcompartments (BMCs), as a scaffold for metabolic enzymes represents a sophisticated approach that can both insulate and integrate the incorporation of challenging metabolic pathways into industrially important bacterial hosts. Here we took a synthetic biology approach and introduced the model shell system derived from the myxobacterium Haliangium ochraceum (HO shell) into the industrially relevant organism Zymomonas mobilis with the aim of constructing a BMC-based spatial scaffolding platform. SDS-PAGE, transmission electron microscopy, and dynamic light scattering analyses collectively demonstrated the ability to express and purify empty capped and uncapped HO shells from Z. mobilis. As a proof of concept to internally load or externally decorate the shell surface with enzyme cargo, we have successfully targeted fluorophores to the surfaces of the BMC shells. Overall, our results provide the foundation for incorporating enzymes and constructing BMCs with synthetic biochemical pathways for the future production of high-value products in Z. mobilis.

SERS detection of thiram using a 3D sea cucumber-like composite flexible porous substrate.

Nowadays, trace detection of thiram is in urgent demand due to its widespread application in agriculture and significant harmful effects on public health. In this work, a three-dimensional (3D) sea cucumber-like flexible porous surface-enhanced Raman scattering (SERS) substrate composed of a poly(vinylidene fluoride) (PVDF) membrane, ZnO nanorods, gold films, and Ag nanoparticles (Ag/Au/ZnO/P) has been established for the highly sensitive detection of thiram. The substrate takes advantage of the 3D morphology of the Ag/Au/ZnO system on a flexible porous PVDF membrane to produce abundant plasmonic hot spots. Meanwhile, the employment of an AgNPs/Au shell system combined the benefits of both gold and silver metals, thus guaranteeing stable and sensitive detection. With 4-mercaptobenzoic acid (4-MBA) as a probe molecule, the Ag/Au/ZnO/P substrate exhibited excellent linear detection in the range of 10-11-10-5 M, with a correlation coefficient (R2) of 0.99 and an enhancement cofactor of 7.09 × 107. The substrate exhibited excellent uniformity with a related standard deviation (RSD) value of 3.82% and demonstrated high stability during a 15 d-storage test. In addition, the substrate could detect thiram in an aqueous solution at concentrations as low as 10-10 M with excellent selectivity. Meanwhile, thiram on the surface of apple peel could be easily detected by the Ag/Au/ZnO/P substrate with the "paste-and-peel" method in less than 10 s, and the detection limit could be as low as 0.48 ng cm-2. Overall, the remarkable performance of the Ag/Au/ZnO/P SERS substrate demonstrated its great potential for the environmental monitoring of thiram.

A DFT study of the isomer variety of dimer-core argento-carbon clusters: From “butterflies” to side-attached to core–shell systems

Mixed metal-based nanosystems play increasingly important roles in modern technologies, and combination of silver and carbon have various current applications. Present DFT-based study addresses small carbon-silver clusters with minimal dicarbon component and predicts a few groups of flat and 3D isomers. They are analyzed and compared in terms of structure and stability, charge distribution and polarity, vibrations, and IR spectra. Structures with the C2 dopant at the periphery or centre of the Agn (n = 4–18) hosts are considered, found to exhibit considerable stabilities, and their evolution with the systems size is followed. Simulated IR spectra are predicted to be mainly represented by bands at low frequencies, characteristically dominated by a brightest line which can, however, split upon encapsulation of the carbon core inside the silver shell. Relative intensities of the spectra are related to the structural features, and a hypothetical sequential fragment-based exothermic mechanism for the core–shell system formation is considered.