Facile in situ synthesis and characterization of Fe@Si/zeolite Na composites with magnetic core–shell structures from natural materials for enhanced curcumin loading capacity

Curcumin is a natural polyphenol that is used in various traditional medicines.However,its inherent properties,such as its rapid degradation and metabolism,low bioavailability,and short half-life,are serious problems that must be resolved.To this end,a drug carrier incorporating natural magnetic cores in a zeolite framework was developed and applied to the loading of curcumin in ethanol solutions.In this system,curcumin is encapsulated in a zeolite Na(ZNA)magnetic core–shell structure(Fe@Si/ZNA),which can be easily synthesized using an in situ method.Synthesis of Fe_(3)O_(4) nanoparticles was carried out from natural materials using a co-precipitation method.Analysis of the prepared magnetic core–shell structures and composites was carried out using vibrating-sample magnetometery,Fourier transform infrared spectroscopy,transmission electron microscopy,and x-ray diffraction.The cumulative loading of curcumin in the ZNA composite with 9%nanoparticles was found to reach 90.70%with a relatively long half-life of 32.49 min.Stability tests of curcumin loading in the composite showed that adding magnetic particles to the zeolite framework also increased the stability of the composite structure.Adsorption kinetics and isotherm studies also found that the system follows the pseudo-second-order and Langmuir isotherm models.

Enhancing electromagnetic wave absorption with core‐shell structured SiO_(2)@MXene@MoS_(2)nanospheres

Material composition and structural design are important factors influencing the electromagnetic wave(EMW)absorption performance of materials.To alleviate the impedance mismatch attributed to the high dielectric constant of Ti_(3)C_(2)T_(x)MXene,we have successfully synthesized core‐shell structured SiO_(2)@MXene@MoS_(2)nanospheres.This architecture,comprising SiO_(2)as the core,MXene as the intermediate layer,and MoS_(2)as the outer shell,is achieved through an electrostatic self‐assembly method combined with a hydrothermal process.This complex core‐shell structure not only provides a variety of loss mechanisms that effectively dissipate electromagnetic energy but also prevents self‐aggregation of MXene and MoS_(2)nanosheets.Notably,the synergistic combination of SiO_(2)and MoS_(2)with highly conductive MXene enables the suitable dielectric constant of the composites,ensuring optimal impedance matching.Therefore,the core‐shell structured SiO_(2)@MXene@MoS_(2)nanospheres exhibit excellent EMW absorption performance,featuring a remarkable minimum reflection loss(RL_(min))of−52.11 dB(2.4 mm).It is noteworthy that these nanospheres achieve an ultra‐wide effective absorption bandwidth(EAB)of 6.72 GHz.This work provides a novel approach for designing and synthesizing high‐performance EMW absorbers characterized by“wide bandwidth and strong reflection loss.”

Heterostructural NiFeW disulfide and hydroxide dual‐trimetallic core‐shell nanosheets for synergistically effective water oxidatio

A stable and highly active core‐shell heterostructure electrocatalyst is essential for catalyzing oxygen evolution reaction(OER).Here,a dual‐trimetallic core‐shell heterostructure OER electrocatalyst that consists of a NiFeWS_(2)inner core and an amorphous NiFeW(OH)_(z)outer shell is designed and synthesized using in situ electrochemical tuning.The electrochemical measurements of different as‐synthesized catalysts with a similar mass loading suggest that the core‐shell Ni_(0.66)Fe_(0.17)W_(0.17)S_(2)@amorphous NiFeW(OH)_(z)nanosheets exhibit the highest overall performance compared with that of other bimetallic reference catalysts for the OER.Additionally,the nanosheet arrays were in situ grown on hydrophilic‐treated carbon paper to fabricate an integrated three‐dimensional electrode that affords a current density of 10 mA cm^(−2)at a small overpotential of 182 mV and a low Tafel slope of 35 mV decade^(−1)in basic media.The Faradaic efficiency of core‐shell Ni_(0.66)Fe_(0.17)W_(0.17)S_(2)@amorphous NiFeW(OH)_(z)is as high as 99.5%for OER.The scanning electron microscope,transmission electron microscope,and X‐ray photoelectron spectroscopy analyses confirm that this electrode has excellent stability in morphology and elementary composition after long‐term electrochemical measurements.Importantly,density functional theory calculations further indicate that the core‐shell heterojunction increased the conductivity of the catalyst,optimized the adsorption energy of the OER intermediates,and improved the OER activity.This study provides a universal strategy for designing more active core‐shell structure electrocatalysts based on the rule of coordinated regulation between electronic transport and active sites.

Full-Scale Isogeometric Topology Optimization of Cellular Structures Based on Kirchhoff-Love Shells

Cellular thin-shell structures are widely applied in ultralightweight designs due to their high bearing capacity and strength-to-weight ratio.In this paper,a full-scale isogeometric topology optimization(ITO)method based on Kirchhoff-Love shells for designing cellular tshin-shell structures with excellent damage tolerance ability is proposed.This method utilizes high-order continuous nonuniform rational B-splines(NURBS)as basis functions for Kirchhoff-Love shell elements.The geometric and analysis models of thin shells are unified by isogeometric analysis(IGA)to avoid geometric approximation error and improve computational accuracy.The topological configurations of thin-shell structures are described by constructing the effective density field on the controlmesh.Local volume constraints are imposed in the proximity of each control point to obtain bone-like cellular structures.To facilitate numerical implementation,the p-norm function is used to aggregate local volume constraints into an equivalent global constraint.Several numerical examples are provided to demonstrate the effectiveness of the proposed method.After simulation and comparative analysis,the results indicate that the cellular thin-shell structures optimized by the proposed method exhibit great load-carrying behavior and high damage robustness.

Structural Analysis of TiC and TiC-C Core-Shell Nanostructures Produced by Pulsed-Laser Ablation

This paper reports on the ablation process of a pure Ti solid target immersed in a C-enriched acetone solution, leading to the production of titanium carbide (TiC) and Ti-C core-shell nanostructures. The used route of synthesis is generally called pulsed laser ablation in liquid (PLAL). The presence of carbon structures in the solution contributed to the carbon content in the produced Ti-based nanomaterials. The atomic composition of the produced nanostructures was analyzed using SEM-EDS, while TEM micrographs revealed the formation of spherical TiC and core-shell nanostructures ranging from 40 to 100 nm. The identification of atomic planes by HRTEM confirmed a 10 nm diameter C-shell with a graphite structure surrounding the Ti-core. Raman spectroscopy allowed for the identification of D and G peaks for graphite and a Raman signal at 380 and 600 cm−1, assigned to TiC. The results contribute to the state-of-the-art production of TiC and Ti-C core-shell nanostructures using the PLAL route.

Control and vibration analyses of a sandwich doubly curved micro-composite shell with honeycomb,truss,and corrugated cores based on the fourth-order shear deformation theory

Curved shells are increasingly utilized in applied engineering due to their shared characteristics with other sandwich structures,flexibility,and attractive appearance.However,the inability of controlling and regulating vibrations and destroying them afterward is a challenge to scientists.In this paper,the curve shell equations and a linear quadratic regulator are adopted for the state feedback design to manage the structure vibrations in state space forms.A five-layer sandwich doubly curved micro-composite shell,comprising two piezoelectric layers for the sensor and actuator,is modeled by the fourth-order shear deformation theory.The core(honeycomb,truss,and corrugated)is analyzed for the bearing of transverse shear forces.The results show that the honeycomb core has a greater effect on the vibrations.When the parameters related to the core and the weight percentage of graphene increase,the frequency increases.The uniform distribution of graphene platelets results in the lowest natural frequency while the natural frequency increases.Furthermore,without taking into account the piezoelectric layers,the third-order shear deformation theory(TSDT)and fourth-order shear deformation theory(FOSDT)align closely.However,when the piezoelectric layers are incorporated,these two theories diverge significantly,with the frequencies in the FOSDT being lower than those in the TSDT.

Structure–performance relationship of Au nanoclusters in electrocatalysis:Metal core and ligand structure

Remarkable progress has characterized the field of electrocatalysis in recent decades,driven in part by an enhanced comprehension of catalyst structures and mechanisms at the nanoscale.Atomically precise metal nanoclusters,serving as exemplary models,significantly expand the range of accessible structures through diverse cores and ligands,creating an exceptional platform for the investigation of catalytic reactions.Notably,ligand‐protected Au nanoclusters(NCs)with precisely defined core numbers offer a distinct advantage in elucidating the correlation between their specific structures and the reaction mechanisms in electrocatalysis.The strategic modulation of the fine microstructures of Au NCs presents crucial opportunities for tailoring their electrocatalytic performance across various reactions.This review delves into the profound structural effects of Au NC cores and ligands in electrocatalysis,elucidating their underlying mechanisms.A detailed exploration of the fundamentals of Au NCs,considering core and ligand structures,follows.Subsequently,the interaction between the core and ligand structures of Au NCs and their impact on electrocatalytic performance in diverse reactions are examined.Concluding the discourse,challenges and personal prospects are presented to guide the rational design of efficient electrocatalysts and advance electrocatalytic reactions.

A core-shell copper oxides-cobalt oxides heterostructure nanowire arrays for nitrate reduction to ammonia with high yield rate

Electrochemical nitrate reduction to ammonia(NRA) can realize the green synthesis of ammonia(NH3) at ambient conditions, and also remove nitrate contamination in water. However, the current catalysts for NRA still face relatively low NH3yield rate and poor stability. We present here a core-shell heterostructure comprising cobalt oxide anchored on copper oxide nanowire arrays(CuO NWAs@Co_(3)O_(4)) for efficient NRA. The CuO NWAs@Co_(3)O_(4)demonstrates significantly enhanced NRA performance in alkaline media in comparison with plain CuO NWAs and Co_(3)O_(4)flocs. Especially, at-0.23 V vs. RHE, NH_(3) yield rate of the CuO NWAs@Co_(3)O_(4)reaches 1.915 mmol h^(-1)cm^(-2),much higher than those of CuO NWAs(1.472 mmol h^(-1)cm^(-2)), Co_(3)O_(4)flocs(1.222 mmol h^(-1)cm^(-2)) and recent reported Cu-based catalysts.It is proposed that the synergetic effects of the heterostructure combing atom hydrogen adsorption and nitrate reduction lead to the enhanced NRA performance.

The Effect of Core Eccentricity on the Structural Behavior of Concrete Tall Buildings

The main purpose of this paper is to investigate the effect of core eccentricity on the structural behavior of concrete tall buildings.Concrete buildings of 55 floors with plan dimensions 48.0×48.0 m2 were investigated.Three cases of main core locations are studied:centric(A),eccentric by one sixth(B)and one third(C)of building width.The three-dimensional finite element method has been used in conducting structural analysis through ETABS software.Gravity and lateral(wind and seismic)loadings are applied to all building cases.It has been concluded that the core location is the prime parameter governing the structural behavior of tall buildings.Although the first two cases(A,B)have acceptable and similar structural behaviors conforming to code limits,in the third case(C),the building behavior came beyond code limits.The author introduced remedial action by adding two secondary cores in the opposite direction of the main core(C-R)to restore the building behavior to the code limits.The results of this action were satisfactory.

Constructing a hollow core-shell structure of RuO_(2) wrapped by hierarchical porous carbon shell with Ru NPs loading for supercapacitor

Hollow core-shell structure nanomaterials have been broadly used in energy storage, catalysis, reactor,and other fields due to their unique characteristics, including the synergy between different materials,a large specific surface area, small density, large charge carrying capacity and so on. However, their synthesis processes were mostly complicated, and few researches reported one-step encapsulation of different valence states of precious metals in carbon-based materials. Hence, a novel hollow core-shell nanostructure electrode material, RuO_(2)@Ru/HCs, with a lower mass of ruthenium to reduce costs was constructed by one-step hydrothermal method with hard template and co-assembled strategy, consisting of RuO_(2) core and ruthenium nanoparticles(Ru NPs) in carbon shell. The Ru NPs were uniformly assembled in the carbon layer, which not only improved the electronic conductivity but also provided more active centers to enhance the pseudocapacitance. The RuO_(2) core further enhanced the material’s energy storage capacity. Excellent capacitance storage(318.5 F·g^(-1)at 0.5 A·g^(-1)), rate performance(64.4%) from 0.5 A·g^(-1)to 20 A·g^(-1), and cycling stability(92.3% retention after 5000 cycles) were obtained by adjusting Ru loading to 0.92%(mass). It could be attributed to the wider pore size distribution in the micropores which increased the transfer of electrons and protons. The symmetrical supercapacitor device based on RuO_(2)@Ru/HCs could successfully light up the LED lamp. Therefore, our work verified that interfacial modification of RuO_(2) and carbon could bring attractive insights into energy density for nextgeneration supercapacitors.

One-dimensional ZnS-based Hetero-,Core/shell and Hierarchical Nanostructures

A focus of the current nanotechnology has shifted from routine fabrication of nanostructures to designing functional electronic devices and realizing their immense potentials for applications. Due to infusion of multi-functionality into a single system, the utilization of hetero-, core/shell and hierarchical nanostructures has become the key issue for building such devices. ZnS, due to its direct wide bandgap, high index of refraction, high transparency in the visible range and intrinsic polarity, is one of the most useful semiconductors for a wide range of electronics applications. This article provides a dense review of the state-of-the-art research activities in one-dimensional （1D） ZnS-based hetero-, core/shell and hierarchical nanostructures. The particular emphasis is put on their syntheses and applications.

Type-Ⅱ Core/Shell Nanowire Heterostructures and Their Photovoltaic Applications

Nanowire-based photovoltaic devices have the advantages over planar devices in light absorption and charge transport and collection.Recently,a new strategy relying on type-Ⅱ band alignment has been proposed to facilitate efficient charge separation in core/shell nanowire solar cells.This paper reviews the type-Ⅱ heterojunction solar cells based on core/shell nanowire arrays,and specifically focuses on the progress of theoretical design and fabrication of type-Ⅱ Zn O/Zn Se core/shell nanowire-based solar cells.A strong photoresponse associated with the type-Ⅱ interfacial transition exhibits a threshold of 1.6 e V,which demonstrates the feasibility and great potential for exploring all-inorganic versions of type-Ⅱ heterojunction solar cells using wide bandgap semiconductors.Future prospects in this area are also outlooked.

Effect of milling process on the core-shell structures and dielectric properties of fine-grained BaTiO_3-based X7R ceramic materials

Fine-grained BaTiO3-based X7R ceramic materials were prepared and the effects of milling process on the core-shell structures and dielectric properties were investigated using scanning electron microscope, transmission electron microscope, and energy dispersive spectroscopy （EDS）. As the milling time extends, the dielectric constant of the ceramics increases, whereas the temperature coefficient of capacitance at 125℃ drops quickly. The changes in dielectric properties are considered relevant to the microstructure evolution caused by the milling process. Defects on the surface of BaTiO3 particles increase because of the effects of milling process, which will make it easier for additives to diffuse into the interior grains. As the milling time increases, the shell region gets thicker and the core region gets smaller; however, EDS results show that the chemical inhomogeneity between grain core and grain shell becomes weaker.

Gap-plasmon of Fe3O4@Ag Core-shell Nanostructures for Highly Enhanced Fluorescence Detection of Rhodamine B

A novel gap-plasmon of Fe3O4@Ag core-shell nanoparticles for surface enhanced fluorescence detection of Rhodamine B（RB） was developed. Fe3O4@Ag core-shell nanostructures with Ag shell and Fe3O4 core were synthetized by self-assembled method with the assistance of 3-mercaptopropyl trimethoxy silane（MPTS）. To study the RB fluorescence enhanced by gap-plasmon, the fluorescence properties of RB on the substrates with different nanogap densities were systematically investigated, and the results showed that the fluorescence intensity of RB on Fe3O4@Ag core-shell NPs substrate was much stronger than that on bare glass substrate, and the fluorescence intensity was further improved by using multilayer Fe3O4@Ag core-shell NPs substrate which had higher nanogap density. Different from the mechanism that is based on the maximum overlap of the surface plasmon resonance（SPR） band and emission band, the mechanism of the fluorescence enhancement in our work is based on the localized surface plasmon（LSP） and the gap plasmon near-field coupling with the Fe3O4@Ag core-shell NPs. Besides, the detection limit obtained was as low as 1×10^（-7） mol/L, and the Fe3O4@Ag core-shell NPs substrate had high selectivity for RB fluorophores. It was demonstrated that the Fe3O4@Ag core-shell NPs substrate had activity, good stability, and selectivity for fluorescence detection of RB. And the detection of RB by the surface plasmon enhanced fluorescence was more convenient and rapid than the traditional detection methods in previous works.

Understanding the growth mechanisms of metal-based core–shell nanostructures revealed by in situ liquid cell transmission electron microscopy

Metal-based core-shell nanostructures have garnered enduring interest due to their unique properties and functionalities.However,their growth and transformation mechanisms in liquid media remain largely unknown because they lack direct observation of the dynamic growth process with high spatial and temporal resolution.Developing the in situ liquid cell transmission electron microscopy(TEM)technique offers unprecedented real-time imaging and spectroscopy capabilities to directly track the evolution of structural and chemical transformation of metal-based core–shell nanostructures in liquid media under their working condition.Here,this review highlights recent progress in utilizing in situ liquid cell TEM characterization technique in investigating the dynamic evolution of material structure and morphology of metal-based core–shell nanostructures at the nano/atomic scale in real-time.A brief introduction of the development of liquid cells for in situ TEM is first given.Subsequently,recent advances in in situ liquid cell TEM for the fundamental study of growth mechanisms of metal based core–shell nanostructures are discussed.Finally,the challenge and future developments of metalbased core–shell nanostructures for in situ liquid cell TEM are proposed.Our review is anticipated to inspire ongoing interest in revealing unseen growth dynamics of core–shell nanostructures by in situ liquid cell TEM technique.

MnHCF/MnO_2 Core-shell Nanostructures as Cathode Material for Supercapacitors with High Energy Density

A nanocomposite of manganese dioxide coated manganese hexacyanoferrate was synthesized by a facile co-precipitation method and tested as active electrode material for an electrochemical supercapacitor. A way called "Deep electro-oxidation" was used to generate manganese dioxide coated layer for stabilizing the electrode material. The structure and ingredient of the resulting MnHCF/MnO2 composites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray Photoelectron Spectroscopy. Electrochemical testing showed a capacitance of 225.6 F/g at a sweep rate of 5 mV/s within a voltage range of 1.3 V, and high energy density of 37.2 Wh/kg at a current density of 0.5 A/g in galvanostatic charge/discharge cycling. It is suggested that the two different components, manganese hexacyanoferrate core and manganese dioxide shell, lead to an integrated electrochemical behavior, and an enhanced capacitor. The electrochemical testing and corresponding XPS analysis also demonstrated that the manganese coordinated by cyanide groups via nitrogen atoms in MnHCF did not get involved in the charge storage process during potential cycles.

Fluorescent Superparamagnetic Core-Shell Nanostructures: Facile Synthesis of Fe@C-CN_xParticles for Reusable Photocatalysts

Synthesis and characterization of hybrid fluorescent superparamagnetic core-shell particles of Fe@C-CNx composition are presented for the first time. The prepared Fe@C-CNx hybrid nanoparticles were found to possess multifunctionality by exhibiting strong superparamagnetic properties and bright fluorescence emissions at 500 nm after the excitation with light in the UV-visible range. Fe@C-CNx also exhibits photocatalytic activities for organic dye degradation comparable to pure amorphous CNx with reusability through magnetic separation. The combination of magnetic and fluorescent properties of core-shell Fe@C-CNx nanoparticles opens opportunities for their application as sensors and magnet manipulated reusable photocatalysts. Superparamagnetic Fe@C core-shell nanoparticles were used as the template material in the synthesis, where the carbon shell was functionalized through one-step free-radical addition of alkyl groups terminated with carboxylic acid moieties. The method utilizes the organic acyl peroxide of dicarboxylic acid (succinic acid peroxide) as a non-oxidant functional free radical precursor for functionalization. Further, covalently functionalized succinyl-Fe@C core-shell nanoparticles were coated with the amorphous carbon nitride (CNx) generated by an in-situ solution-based chemical reaction of cyanuric chloride with lithium nitride. A detailed physicochemical characterization of the microstructure, magnetic and fluorescence properties of the synthesized hybrid nanoparticles is provided.

Seismic isolation analysis of FPS bearings in spatial lattice shell structures

A theoretical model of a friction pendulum system （FPS） is introduced to examine its application for the seismic isolation of spatial lattice shell structures. An equation of motion of the lattice shell with FPS bearings is developed. Then, seismic isolation studies are performed for both double-layer and single-layer lattice shell structures under different seismic input and design parameters of the FPS. The influence of frictional coefficients and radius of the FPS on seismic performance are discussed. Based on the study, some suggestions for seismic isolation design of lattice shells with FPS bearings are given and conclusions are made which could be helpful in the application of FPS.

Preparation of a p-n heterojunction BiFeO_3@TiO_2 photocatalyst with a core–shell structure for visible-light photocatalytic degradation

Magnetically separable bismuth ferrite(BiFeO3)nanoparticles were fabricated by a citrate self‐combustion method and coated with titanium dioxide(TiO2)by hydrolysis of titanium butoxide(Ti(OBu)4)to form BiFeO3@TiO2core-shell nanocomposites with different mass ratios of TiO2to BiFeO3.The photocatalytic performance of the catalysts was comprehensively investigated via photocatalytic oxidation of methyl violet(MV)under both ultraviolet and visible‐light irradiation.The BiFeO3@TiO2samples exhibited better photocatalytic performance than either BiFeO3or TiO2alone,and a BiFeO3@TiO2sample with a mass ratio of1:1and TiO2shell thickness of50-100nm showed the highest photo‐oxidation activity of the catalysts.The enhanced photocatalytic activity was ascribed to the formation of a p‐n junction of BiFeO3and TiO2with high charge separation efficiency as well as strong light absorption ability.Photoelectrochemical Mott-Schottky(MS)measurements revealed that both the charge carrier transportation and donor density of BiFeO3were markedly enhanced after introduction of TiO2.The mechanism of MV degradation is mainly attributed to hydroxyl radicals and photogenerated electrons based on energy band theory and the formation of an internal electrostatic field.In addition,the unique core-shell structure of BiFeO3@TiO2also promotes charge transfer at the BiFeO3/TiO2interface by increasing the contact area between BiFeO3and TiO2.Finally,the photocatalytic activity of BiFeO3@TiO2was further confirmed by degradation of other industrial dyes under visible‐light irradiation.

Design and Synthesis of Cu@CuS Yolk–Shell Structures with Enhanced Photocatalytic Activity

Non-spherical Cu@Cu S yolk–shell structures are successfully obtained using Cu_2 O cube templates in a process combining rapid surface sulfidation followed by disproportionation of the Cu_2 O core upon treatment with a hydrochloric acid solution. By employing the above method,Cu@Cu S yolk–shell structures with different morphologies,including octahedral, truncated octahedral, and cuboctahedral shapes, can be synthesized. The void space within the hollow structures provides a unique confined space, where the metallic copper present in the core of a shell can be protected from agglomeration and oxidation. Furthermore,the presence of metal copper in these hollow structurescontributes to improvement in the photocatalytic properties of these materials. The application of these Cu@Cu S structures indeed shows clearly improved photocatalytic performance.