Nanoscale Structures Research Articles

Review of: "Nanolithography is a branch of nanotechnology that deals with the study and application of nanostructures of nanoscale structures,"

Review of: "Nanolithography is a branch of nanotechnology that deals with the study and application of nanostructures of nanoscale structures,"

Investigating the Nano-Scale Structure and Composition Dynamics During the Phase Transition Towards Complete Separation of CeO2-ZrO2 Solid Solution

Over the past decades, CeO2-ZrO2 solid solution (CZO) have rapidly replaced conventional CeO2 as a support material in the three-way catalysts (TWCs) because of its superior oxygen releasing/storing capability. However,...

Photoacid-macroion assemblies: how photo-excitation switches the size of nano-objects.

Electrostatic self-assembly of photoacids with oppositely charged macroions yields supramolecular nano-objects in aqueous solutions, whose size is controlled through light irradiation. Nano-assemblies are formed due to electrostatic attractions and mutual hydrogen bonding of the photoacids. Irradiation with UV light leads to the deprotonation of the photoacid and, consequently, a change in particle size. Overall, the hydrodynamic radii of the well-defined photoacid-macroion nano-objects lie between 130 and 370 nm. For a set of photoacids, we determine the acidity constants in the ground and excited state, discuss the sizes of photoacid-macroion nano-objects (by dynamic and static light scattering), their composition and the particle shapes (by small-angle neutron scattering), and relate their charge characteristics to size, structure and shape. We investigate the association thermodynamics and relate nanoscale structures to thermodynamics and, in turn, thermodynamics to molecular features, particularly the ionization energy of the photoacid hydroxyl group proton. Structure-directing effects completely differ from those for previously investigated systems, with hydrogen bonding and entropic effects playing a major role herein. This combined approach allows developing a comprehensive understanding of assembly formation and photo-response, anchored in molecular parameters (pKa, ionization energy, substituent group location), charge characteristics, and the association enthalpy and entropy. This fundamental understanding again paves the way for tailoring application solutions with novel photoresponsive materials.

Olive leaf extract-assisted green synthesis of cd nano complex: A combined experimental and theoretical study.

Research in the synthesis of Schiff base ligands and their metal complexes using olive leaf extracts as a green reducing agent is an exciting area of study. In this research, a Schiff base ligand is created by combining 1-hydroxy-2-naphthaldehyde and amino-N-(4,6-dimethylpyrimidin-2-yl)-4-benzenesulfonamide. The synthetic Schiff base is then utilized for the production of a Cd(II) nano complex for the first time with olive leaf extracts serving as the green reducing agent. The extract is obtained by harvesting, drying, and grinding the olive leaves. Various analytical techniques, including 1H NMR, 13C NMR spectroscopy, scanning electron microscope (SEM), and conductivity studies, are employed to analyze the Schiff base and its Cd(II) complex. Quantum chemical calculations are also conducted to explore the different conformers of the Cd(II) complex and their stabilities, shedding light on the synthesis pathways of the Schiff base ligand and Cd(II) complex. Extensive DFT-based geometry optimizations and frequency calculations are carried out for 1-hydroxy-2-naphthaldehyde,amino-N-(4,6-dimethylpyrimidin-2-yl)-4-benzenesulfonamide, the Schiff base ligand, and the corresponding Cd(II) complex. Experimental and theoretical analyses confirm the presence of the azomethine (-HC = N-) group in the Schiff base and validate the formation of the Cd(II) complex in a 2:1 metal-to-ligand ratio through physicochemical characterization methods, highlighting the nanoscale structure of the complex. Combining thorough physicochemical investigations with molecular modeling simulations and the sustainable synthesis of metal complexes, valuable insights into their properties and potential applications in catalysis and drug delivery are obtained.

Preparation and properties of geopolymer containing phosphoric acid-activated fly ash and mechanically-milled kaolinite: Experiments and density function theory

The environmental pollution resulted from the stacking of solid wastes, and the 250 kg CO2 emission caused by calcined a ton of kaolinite have become an urgent problem to be solved. In this study, a novel phosphoric acid-activated geopolymer was developed, which was composed of fly ash (FA), mechanically activated-kaolinite (MAK). The influences of phosphoric acid concentration, mechanical grinding duration, and curing temperature were investigated. Microstructural properties of FAMAK geopolymers were examined through a serious of tests. Furthermore, the Gibbs free energy and nano-scale structure characteristics of acid-activated hydration products were calculated for the first time by using density functional theory. The results show that the optimal mass ratio of FA to MAK is 7:3 with 8 mol/L phosphoric acid, which led to the maximum compressive strength of 36.6 MPa at 56-day. Besides, the optimal grinding time is 3 h and temperature is 40 °C. Moreover, the content of silicon promotes the polymerization reaction. The valence and bonding of aluminum are primarily affected by its coordination number. The key outcomes in this study provides a low-carbon cementitious materials, which can achieve the double benefits of carbon reduction and the utilization of solid wastes.

High Performance and Scalable Hybrid Memristor-CMOS Based Full Adder

The field of digital computation has recently drawn attention to the memristor as a circuit element due to its nanoscale structure and integration capabilities with MOSFETs. As a result, there have been various attempts to use hybrid memristor-CMOS circuits to rebuild the fundamental digital building blocks. This paper presents a new hybrid memristor-CMOS-based full adder (HMC-FA) design. This design aims to minimize propagation delay, power dissipation, power delay product (PDP), and device count (memristor and transistor count). The proposed design is implemented in Cadence Virtuoso toolset utilizing CMOS gpdk 180nm process technology parameters. Comparative investigation demonstrates that the proposed HMC-FA improves PDP by 71.95%−99.83%. The proposed circuit is designed with 12 transistors and 6 memristors. The proposed design consumes 8.24µW of total power while the propagation delay is 112.71ps at 1.8V supply voltage. To verify the scalability of the HMC-FA cell, full adders up to 32-bit word length are designed, and performance parameters are evaluated at 1.8V, 100MHz supply voltage.

Atomic Layer Depostion within Polymers Templates for Spatially Controlled Growth and Doped Materials

Today’s nanofabrication techniques require multistep and costly processes in order to fabricate complex, multi-materials nanostructures. Performing atomic layer deposition (ALD) within polymeric templates can offer a simple solution for nanostructure fabrication. In this process, named sequential infiltration synthesis (SIS), high partial pressures and long exposures times lead to inorganic materials growth within polymers. Sequential polymer removal results in polymer-templated inorganic nanostructure. While SIS shows great potential in fabricating large variety of structures, it is currently limited to a single material growth process.In our research, we utilized SIS properties to achieve two different objectives: selective spatial growth and homogenous growth for doped materials. We demonstrated, for the first time, multi-material SIS process with control over the spatial location of each material and fabricate heterostructure nanorods and nanowires. Doping materials were fabricated using simultaneously growth of two precursors.We studied SIS within self-assembled block copolymer (BCP) films and electrospun polymer fibers and developed multi-material SIS, where two metal oxides are grown together in a single process, with precise control over their location within the polymer template. We used cylinder forming poly (styrene-block-methyl methacrylate) (PS-b-PMMA) films and electrospun PMMA as the polymeric template and DEZ (diethyl zinc), TMA (trimethyl aluminum) as the organometallic precursors. We achieved control over the growth location of each metal oxide by tuning the organometallic precursors diffusion time, forming heterostructures after polymer removal. A short exposure of the first precursor resulted in a limited growth only at the outer part of the polymer, while a long exposure of the second precursor enabled it to reach the full depth of the polymer besides the section which was already occupied by the first precursor. An exposure to water completed the cycle. We demonstrated this process on BCP films to achieve AlOx-ZnO nanorods arrays (Figure 1A-B) and on polymer fibers to achieve AlOx-ZnO fibers (Figure 1C-D). We performed structural characterization using scanning and transmission electron microscopy (SEM and TEM, respectively) to characterize the nanowires and nanorods as well as three-dimensional characterization scanning TEM (STEM) tomography and energy-dispersive X-ray spectroscopy (EDS) STEM tomography in order to probe the structure and the chemical composition in 3D. To fabricate doped materials, we applied SIS process with TMA and DEZ in the same exposure within homopolymer film. We preformed SEM-EDS to quantify each element and evaluate the doping percentage. This research opens new pathways for multi-materials nano scale structure fabrication through ALD-based growth within polymers.Figure 1 caption: AlOx-ZnO nanorods array: cross-sectional views using A) EsB detector and B) secondary electron in-lens detector. AlOx-ZnO fibers C) EDS map D) HAADF image [1] R. Azoulay et al., Small, 15, 1904657 (2019).[2] R. Azoulay et al., ACS Appl. Nano Mater., 5, 7228 (2022). Figure 1

Spontaneous Synchronization of Two Bistable Pyridine-Furan Nanosprings Connected by an Oligomeric Bridge.

The intensive development of nanodevices acting as two-state systems has motivated the search for nanoscale molecular structures whose long-term conformational dynamics are similar to the dynamics of bistable mechanical systems such as Euler arches and Duffing oscillators. Collective synchrony in bistable dynamics of molecular-sized systems has attracted immense attention as a potential pathway to amplify the output signals of molecular nanodevices. Recently, pyridine-furan oligomers of helical shape that are a few nanometers in size and exhibit bistable dynamics similar to a Duffing oscillator have been identified through molecular dynamics simulations. In this article, we present the case of dynamical synchronization of these bistable systems. We show that two pyridine-furan springs connected by a rigid oligomeric bridge spontaneously synchronize vibrations and stochastic resonance enhances the synchronization effect.

The fabrication of fluorescent sensor for Fe3+ detection and configurable logic gate operation based on N-doped carbon dots

Herein, fluorescent N-doped carbon dots (N-CDs) were obtained using hydrothermal treatment of polyethyleneimine and melamine. The N-CDs exhibit nanoscale structure, good water solubility, photostability and excellent fluorescence property with a high fluorescence quantum yield of 26 %. The as-prepared N-CDs were selected for the detection of Fe3+ with a fluorescence “OFF-ON” strategy by the mechanism of internal filtration effect (IFE). A good linear relationship can be observed for the concentration of Fe3+ from 0 to 500 μM, and the calculated detection limit (LOD) for Fe3+ was 0.88 μM (3σ/slope). Meanwhile, the N-CDs based sensor can be utilized for tracing Fe3+ in real water samples. In addition, the quenched fluorescence can be recovered with the treatment of l-cysteine, and thus can be designed for quantitative determination of l-cysteine with a fluorescent “ON-OFF-ON” switch. Moreover, a set of resettable, multireadout logic gate operations including OR and AND have been realized for the N-CDs.

Subcooled Pool Boiling on Hierarchical Micro- and Nanostructure-Modified Copper Surfaces in HFE-7100 Dielectric Liquid

ABSTRACT Hierarchical surfaces comprised both microscale and nanoscale structures have been previously studied as a means of targeting multiple length scales to achieve superior pool boiling performance. However, preceding studies have focused almost exclusively on high surface tension working fluids, while technologically important low surface tension fluids have remained largely unexplored. Due to their significantly lower surface tension these liquids tend to push out the air trapped in surface cavities of the heating surface, resulting in fewer nucleation sites compared to the same surface in water at low to moderate superheats. Thus, developing effective surface modification techniques for pool boiling in dielectric liquids and understanding the multiphase physics behind them is a pressing need in order to overcome these performance limitations and accelerate their adoption. In this work, we utilize scalable manufacturing techniques to realize four separate surface types (planar, nanoscale-modified, microscale-modified, and hierarchical) and experimentally determine their respective pool boiling performance within the low surface tension commercial working fluid HFE-7100. A maximum heat transfer enhancement of 125% at 38 K of superheat was observed for the best performing samples, which interestingly were nanoscale-modified and not those of the hierarchical type. Visual observations via high-speed video analysis of vapor bubble behavior are utilized to explain the underlying multiphase physics as to why these samples performed so well and future directions for achieving surface optimization across multiple length scales.

Atomic-scale view of the photoinduced structural transition to form sp3-like bonded order phase in graphite

Photoexcitation of solids often induces structural phase transitions between different ordered phases, some of which are unprecedented and thermodynamically inaccessible. The phenomenon, known as photoinduced structural phase transition (PSPT), is of significant interest to the technological progress of advanced materials processing and the fundamental understanding of material physics. Here, we applied scanning tunnelling microscopy (STM) to directly characterise the primary processes of the PSPT in graphite to form a sp3-like carbon nano-phase called diaphite. The primary challenge was to provide microscopic views of the graphite-to-diaphite transition. On an atomic scale, STM imaging of the photoexcited surface revealed the nucleation and proliferation processes of the diaphite phase; these were governed by the formation of sp3-like interlayer bonds. The growth mode of the diaphite phase depends strongly on the photon energy of excitation laser light. Different dynamical pathways were proposed to explain the formation of a sp3-like interlayer bonding. Potential mechanisms for photon-energy-dependent growth were examined based on the experimental and calculated results. The present results provide insight towards realising optical control of sp2-to-sp3 conversions and the organisation of nanoscale structures in graphene-related materials.

Small and wide angle X-ray scattering to reveal nanoscale structure evolution of the polyamide RO membranes triggered by ethyl acetate

The intrinsic structure of the polyamide separation layer determines the transport of water and salt through a thin film composite membrane. In this work, we probed nanoscale structure variation of the polyamide layers generated by ethyl acetate through small/wide angle X-ray scattering. The gyration radius and physical radius of the polyamide colloidal particles were calculated from the small angle X-ray scattering (SAXS) curves, and the results are confirmed by AFM and SEM. The form factor derived from SAXS curves and horizontal distance between the centers of adjacent benzene rings calculated from the wide angle X-ray scattering (WAXS) curves showed quantitative relationships with membrane performance including water permeability coefficient and salt permeability coefficient. The results derived from SAXS and WAXS curves provided evidence for the formation mechanism of polyamide layers.

Design of high-entropy films as ultra-violet light reflector

This study proposes the design and implementation of high-entropy alloy (HEA) thin films as materials for the reflector of deep ultraviolet light-emitting devices and marks the first application of HEA in optical field. In the material design phase, an Al-Co-Zn-Ni alloy is designed by considering the reflectivity, phase stability and binary formation energy. Reverse Monte Carlo calculation is employed to establish stable atomic structure. Frequency-dependent dielectric equations are derived from first principles calculations, with dielectric constants incorporating contributions from ions and electrons and combining classical Drude and Lorentz models. The dielectric equations yield optical constants that are used to calculate the reflectance. In the experimental phase, we systematically vary the aluminum content and prepare Al-Co-Zn-Ni thin films ranging from pure aluminum to equimolar compositions. In the deep ultraviolet region, the reflectance of thermally treated Al65Zn12Co12Ni11 and Al50Zn16Co17Ni17 thin films is found superior to that of gold by three times. Structural and crystalline changes with varying aluminum content are found, as well as intriguing phase separation and superlattice formation that persist until equimolar compositions. This unique nanoscale structural variation causes the Young's modulus and hardness of Al-Co-Zn-Ni thin films to initially increase and then decrease with decreasing aluminum content. There is a significant increase in the corrosion potential difference when reducing Al contents in Al-Co-Zn-Ni, indicating improved passivation effects as the equimolar composition is approached. By modulating the aluminum content, the nanoscale structure of Al-Co-Zn-Ni can be adjusted, thereby improving its optical, mechanical, corrosion resistance, and thermal stability properties. This demonstrates the high versatility of this material for practical optical applications.

Two energies for conjoining boron nitride nanotorus and nanotube

AbstractOwing to a variety in nanoscale material applications, the conjunction of two nanostructures is frequently researched for potential new applications. Numerous methods are used to model this conjunction process. One such method, the minimization of elastic energy, only considers the axial curvature when modeling conjoined structures. Another method minimizes the Willmore energy, which depends on both the axial and rotational curvatures. In particular, because the catenoid is an absolute minimizer of Willomre energy, a catenoid section can be utilized to conjoin nanostrucrures. Owing to the similarities among carbon nanostructures, we expanded the use of two different energies to join a boron nitride nanotube with a boron nitride nanotorus. The primary objective of this study was to formulate a basic underlying structure from which any small perturbations can be viewed as departures from an ideal model. Accordingly, elastic energy was used to determine the conjunction region for two-dimensional structures, whereas Willmore energy was used to determine the conjunction region for three-dimensional structures. This approach may be extended to produce other hybrid nanoscale structures.

Ultrasound-Responsive Micelle-Encapsulated Mesenchymal Stem Cell-Derived EVs for the Treatment of Lower Limb Microcirculation Disease.

Lower limb microcirculatory ischemic disease is a vascular disorder primarily characterized by limb pain, gangrene, and potential amputation. It can be caused by various factors, such as hyperglycemia, atherosclerosis, and infection. Due to the extremely narrow luminal diameter in lower limb microcirculatory ischemic lesions, both surgical and medical interventions face challenges in achieving satisfactory therapeutic outcomes within the microvessels. Extracellular vesicles derived from mesenchymal stem cells (MSCs-EVs) exhibit promising potential in the treatment of microcirculation ischemic lesions due to their small size and ability to promote angiogenesis. After undergoing substantial losses during the process of EVs transportation, only a minimal fraction of EVs can effectively reach the site of microcirculatory lesions, thereby compromising the therapeutic efficacy for microcirculatory disorders. Herein, an ultrasound-responsive system utilizing 2-(dimethylamino)ethyl methacrylate-b-2-tetrahydropyranyl methacrylate (DMAEMA-b-THPMA) micelles to encapsulate MSCs-EVs has been successfully constructed, with the aim of achieving localized and targeted release of EVs at the site of microcirculatory lesions. The reversible addition-fragmentation chain transfer (RAFT) polymerization method facilitates the successful synthesis of diblock copolymers comprising monomer 2-(dimethylamino)ethyl methacrylate (DMAEMA) and monomer 2-tetrahydropyranyl methacrylate (THPMA). The DMAEMA-b-THPMA micelles exhibit a nanoscale structure, reliable biocompatibility, ultrasound responsiveness, and conspicuous protection of EVs. Furthermore, the implementation of low-energy-density ultrasound can enhance angiogenesis by upregulating the levels of the vascular endothelial growth factor (VEGF). In in vivo experiments, the ultrasound-responsive system of the DMAEMA-b-THPMA micelles and MSCs-EVs synergistically enhances therapeutic efficacy by promoting angiogenesis, improving vascular permeability, and optimizing vascular. In conclusion, this work demonstrates bioapplication of an ultrasound-responsive micellar nanosystem loaded with EVs for the treatment of lower limb microcirculatory ischemic disorders.

Graphene-Based Aerogels for Biomedical Application.

Aerogels are three-dimensional solid networks with incredibly low densities, high porosity, and large specific surface areas. These aerogels have both nanoscale and macroscopic interior structures. Combined with graphene, the aerogels show improved mechanical strength, electrical conductivity, surface area, and adsorption capacity, making them ideal for various biomedical applications. The graphene aerogel has a high drug-loading capacity due to its large surface area, and the porous structure enables controlled drug release over time. The presence of graphene makes it a suitable material for wound dressings, blood coagulation, and bilirubin adsorption. Additionally, graphene's conductivity can help in the electrical stimulation of cells for improved tissue regeneration, and it is also appropriate for biosensors. In this review, we discuss the preparation and advantages of graphene-based aerogels in wound dressings, drug delivery systems, bone regeneration, and biosensors.

A Review on Nanosponges as Nanocarier for Drug Delivery

Nanosponges are innovative nanocarriers that show promise in various fields, including drug delivery and environmental remediation. These nanoscale structures, often composed of polymers or lipids, exhibit unique properties due to their high surface area and versatile encapsulation capabilities. A pivotal study by Liang et al. (2014) demonstrated the potential of nanosponges in sequestering toxins, showcasing their versatility beyond conventional drug delivery systems.[1].

Understanding the Mechanics of the Temporomandibular Joint Osteochondral Interface from Micro- and Nanoscopic Perspectives.

The condylar cartilage of the temporomandibular joint (TMJ) is connected to the subchondral bone by an osteochondral interface that transmits loads without causing fatigue damage. However, the microstructure, composition, and mechanical properties of this interface remain elusive. In this study, we found that structurally, a spatial gradient assembly of hydroxyapatite (HAP) particles exists in the osteochondral interface, with increasing volume of apatite crystals with depth and a tendency to form denser and stacked structures. Combined with nanoindentation, this complex assembly of nanoscale structures and components enhanced energy dissipation at the osteochondral interface, achieving a smooth stress transition between soft and hard tissues. This study comprehensively demonstrates the elemental composition and complex nanogradient spatial assembly of the osteochondral interface at the ultramicroscopic scale, providing a basis for exploring the construction of complex mechanical models of the interfacial region.

Free vibration analysis of functionally graded nanobeams based on surface stress-driven nonlocal model

A surface stress-driven nonlocal model is employed in this manuscript to study the coupled effects of the long-range interaction and surface energy on the free vibrations of nano-beams made of metal-ceramic functionally graded material. The nanobeam theory is formulated based on the Bernoulli-Euler kinematics and surface effects include surface elasticity, surface residual stresses, surface density and rotary inertia. Hamilton’s principle is applied to derive the size-dependent governing equation. The main results of a parametric investigation, carried out considering four different kinematic boundary conditions, i.e. Cantilever, Simply-Supported, Clamped-Pinned and Doubly-Clamped, are also presented and discussed, varying the nonlocal parameter and the material gradient index. The results show how the proposed model is able to capture surface energy effects on the overall dynamic behavior of functionally graded Bernoulli-Euler nanobeams and provides a cost-effective method for the design and the optimization of nano-scaled structures.

Characterization for 3D pore-fracture systems in Hot-Dry-Rock samples from Gonghe Basin, China

As a new type of renewable energy, Hot-Dry-Rock (HDR) is gaining increasing attention. The physical properties of rock influenced by the pore-fracture structure are vital for the hydraulic and chemical characteristics of HDR reservoirs. However, the natural pore-fracture structure in HDR has not been sufficiently studied. To fulfill this gap, we used focused ion beam-scanning electron microscopy (FIB-SEM) to construct three-dimensional (3D) digital models for four granite samples from the deep HDR reservoir in Gonghe Basin, Qinghai Province, China, and obtained the nanoscale structure of the pores and fractures in HDR reservoir for the first time. Our analysis based on the 3D models indicates that the heat transfer area in the HDR reservoir is mainly from fractures and crack-like pores, but a large amount of small but regular pores could be neglected when heat transfer in HDR is considered. The permeability of HDR reservoirs at nanoscale varies from 9.414 nD to 0.082 mD, and the high permeability in this study is accompanied by throughgoing fractures. The variation of porosity and permeability of deep HDR at nanoscale in this study is much more severe than that of shallow granites previously studied at microscale. The performance of geothermal field is significantly influenced by the size of throats and the average size and tortuosity of the interconnected pore-fracture network in HDR. The hydraulic aperture could be 32-58% lower than the mechanical aperture of the natural fractures in HDR reservoirs, which is a vital clue for the numerical simulation associated with enhanced geothermal systems.