Nanoscale Information Research Articles

Free radical detection in precision-cut mouse liver slices with diamond-based quantum sensing

Free radical generation plays a key role in many biological processes including cell communication, maturation, and aging. In addition, free radical generation is usually elevated in cells under stress as is the case for many different pathological conditions. In liver tissue, cells produce radicals when exposed to toxic substances but also, for instance, in cancer, alcoholic liver disease and liver cirrhosis. However, free radicals are small, short-lived, and occur in low abundance making them challenging to detect and especially to time resolve, leading to a lack of nanoscale information. Recently, our group has demonstrated that diamond-based quantum sensing offers a solution to measure free radical generation in single living cells. The method is based on defects in diamonds, the so-called nitrogen-vacancy centers, which change their optical properties based on their magnetic surrounding. As a result, this technique reveals magnetic resonance signals by optical means offering high sensitivity. However, compared to cells, there are several challenges that we resolved here: Tissues are more fragile, have a higher background fluorescence, have less particle uptake, and do not adhere to microscopy slides. Here, we overcame those challenges and adapted the method to perform measurements in living tissues. More specifically, we used precision-cut liver slices and were able to detect free radical generation during a stress response to ethanol, as well as the reduction in the radical load after adding an antioxidant.

Morphology of Copper Nanofoams for Radiation Hydrodynamics and Fusion Applications Investigated by 3D Ptychotomography.

The performance of metal and polymer foams used in inertial confinement fusion (ICF), inertial fusion energy (IFE), and high-energy-density (HED) experiments is currently limited by our understanding of their nanostructure and its variation in bulk material. We utilized an X-ray-free electron laser (XFEL) together with lensless X-ray imaging techniques to probe the 3D morphology of copper foams at nanoscale resolution (28 nm). The observed morphology of the thin shells is more varied than expected from previous characterizations, with a large number of them distorted, merged, or open, and a targeted mass density 14% less than calculated. This nanoscale information can be used to directly inform and improve foam modeling and fabrication methods to create a tailored material response for HED experiments.

Nano-scale corrosion mechanism of T91 steel in static lead-bismuth eutectic: A combined APT, EBSD, and STEM investigation

T91 steel is a candidate material for structural components in lead-bismuth-eutectic (LBE) cooled systems, for example fast reactors and solar power plants [1]. However, the corrosion mechanisms of T91 in LBE remain poorly understood. In this study, we have analysed the static corrosion of T91 in liquid LBE using a range of characterisation techniques at increasingly smaller scales. A unique pattern of liquid metal intrusion was observed that does not appear to correlate with the grain boundary network. Upon closer inspection, electron backscatter diffraction (EBSD) reveals a change in the morphology of grains at the LBE-exposed surface, suggesting a local phase transition. Energy dispersive X-ray (EDX) maps show that Cr is depleted in the T91 material near the LBE interface. Furthermore, we observed the dissolution of all Cr-enriched precipitates in this region. Although the corrosion is conducted in an oxygen deficient environment, both scanning transmission electron microscopy (STEM) and atom probe tomography (APT) reveal a thin surface oxide layer (presumably wüstite) at the LBE-steel interface. Using electron energy loss spectroscopy (EELS) in the STEM, as well as APT, the atomic scale elemental redistribution and 3D morphology of the corrosion interface is investigated. By combining results from these different techniques, several types of oxide phases and structures can be identified. Based on this detailed nano-scale information, we propose potential mechanisms of T91 corrosion in LBE.

Near-Field Terahertz Morphological Reconstruction Nanoscopy for Subsurface Imaging of Protein Layers.

Protein layers formed on solid surfaces have important applications in various fields. High-resolution characterization of the morphological structures of protein forms in the process of developing protein layers has significant implications for the control of the layer's quality as well as for the evaluation of the layer's performance. However, it remains challenging to precisely characterize all possible morphological structures of protein in various forms, including individuals, networks, and layers involved in the formation of protein layers with currently available methods. Here, we report a terahertz (THz) morphological reconstruction nanoscopy (THz-MRN), which can reveal the nanoscale three-dimensional structural information on a protein sample from its THz near-field image by exploiting an extended finite dipole model for a thin sample. THz-MRN allows for both surface imaging and subsurface imaging with a vertical resolution of ∼0.5 nm, enabling the characterization of various forms of proteins at the single-molecule level. We demonstrate the imaging and morphological reconstruction of single immunoglobulin G (IgG) molecules, their networks, a monolayer, and a heterogeneous double layer comprising an IgG monolayer and a horseradish peroxidase-conjugated anti-IgG layer. The established THz-MRN presents a useful approach for the label-free and nondestructive study of the formation of protein layers.

Observations of specimen morphology effects on near-zone-axis convergent-beam electron diffraction patterns.

This work presents observations of symmetry breakages in the intensity distributions of near-zone-axis convergent-beam electron diffraction (CBED) patterns that can only be explained by the symmetry of the specimen and not the symmetry of the unit cell describing the atomic structure of the material. The specimen is an aluminium-copper-tin alloy containing voids many tens of nanometres in size within continuous single crystals of the aluminium host matrix. Several CBED patterns where the incident beam enters and exits parallel void facets without the incident beam being perpendicular to these facets are examined. The symmetries in their intensity distributions are explained by the specimen morphology alone using a geometric argument based on the multislice theory. This work shows that it is possible to deduce nanoscale morphological information about the specimen in the direction of the electron beam - the elusive third dimension in transmission electron microscopy - from the inspection of CBED patterns.

Simultaneous fast XAS/SAXS measurements in an energy-dispersive mode.

X-ray absorption spectroscopy (XAS) and small-angle X-ray scattering (SAXS) are common materials characterization tools at synchrotron radiation facilities used in many research fields. Since XAS can provide element-specific chemical states and local atomic structures and SAXS can provide nano-scale structural information, their complementary use is advantageous for a comprehensive understanding of multiscale phenomena. This paper presents a new method for simultaneous XAS/SAXS measurements with synchrotron radiation. The method employs a polychromatic X-ray beam as in the energy-dispersive XAS technique and captures both the transmission XAS spectrum and the SAXS intensity distribution with an area X-ray detector, which eliminates the energy scan in the conventional methods and realizes the simultaneous data acquisition in a shorter time. We succeeded in obtaining the atomic and nano-scale structures of Pt and Pt/Pd nanoparticles with a data acquisition time of 0.1 s, suggesting the potential for real-time observation of multiscale phenomena.

Single-molecule non-volatile memories: an overview and future perspectives

A single-molecule non-volatile memory is a crucial component of future nanoscale information storage. This article provides an overview of the design, mechanism and prospects of single-molecule non-volatile memories.

Switchable and Functional Fluorophores for Multidimensional Single-Molecule Localization Microscopy.

Multidimensional single-molecule localization microscopy (mSMLM) represents a paradigm shift in the realm of super-resolution microscopy techniques. It affords the simultaneous detection of single-molecule spatial locations at the nanoscale and functional information by interrogating the emission properties of switchable fluorophores. The latter is finely tuned to report its local environment through carefully manipulated laser illumination and single-molecule detection strategies. This Perspective highlights recent strides in mSMLM with a focus on fluorophore designs and their integration into mSMLM imaging systems. Particular interests are the accomplishments in simultaneous multiplexed super-resolution imaging, nanoscale polarity and hydrophobicity mapping, and single-molecule orientational imaging. Challenges and prospects in mSMLM are also discussed, which include the development of more vibrant and functional fluorescent probes, the optimization of optical implementation to judiciously utilize the photon budget, and the advancement of imaging analysis and machine learning techniques.

Energy material analysis via in-situ/operando scanning transmission x-ray microscopy: A review

The development of advanced energy systems is essential for replacing fossil fuel-based societies, and progress in the fundamental understanding of solid-state energy materials has revolutionized this field. In particular, investigating the inhomogeneity of reactions in energy systems requires analysis at the level of individual particles, which are the smallest units in the system. Synchrotron-based scanning transmission X-ray microscopy (STXM) is a valuable tool for exploring reaction and degradation mechanisms, and providing nanoscale site-specific information on chemical and structural changes within single particles. In-situ/operando STXM is particularly useful for observing reactions under well-controlled conditions in real time, thus providing insights into local phenomena obscured by the ensemble effect. This review highlights the research achievements of in-situ/operando STXM in the field of energy materials and provides perspectives for advanced X-ray imaging techniques that can further enhance STXM capabilities.

Micro- and Nanoscale Heterogeneities in Zeolite Beta as Measured by Atom Probe Tomography and Confocal Fluorescence Microscopy.

Micro- and nanoscale information on the activating and deactivating coking behaviour of zeolite catalyst materials increases our current understanding of many industrially applied processes, such as the methanol-to-hydrocarbon (MTH) reaction. Atom probe tomography (APT) was used to reveal the link between framework and coke elemental distributions in 3D with sub-nanometre resolution. APT revealed 10-20 nanometre-sized Al-rich regions and short-range ordering (within nanometres) between Al atoms. With confocal fluorescence microscopy, it was found that the morphology of the zeolite crystal as well as the secondary mesoporous structures have a great effect on the microscale coke distribution throughout individual zeolite crystals over time. Additionally, a nanoscale heterogeneous distribution of carbon as residue from the MTH reaction was determined with carbon-rich areas of tens of nanometres within the zeolite crystals. Lastly, a short length-scale affinity between C and Al atoms, as revealed by APT, indicates the formation of carbon-containing molecules next to the acidic sites in the zeolite.

Nucleic Acid Probes for Single-Molecule Localization Imaging of Cellular Biomolecules.

Endogenous biomolecules in cells are the basis of all life activities. Directly visualizing the structural characteristics and dynamic behaviors of cellular biomolecules is significant for understanding the molecular mechanisms in various biological processes. Single-molecule localization microscopy (SMLM) can circumvent the optical diffraction limit, achieving analysis of the fine structures and biological processes in living cells with nanoscale resolution. However, the large size of traditional imaging probes prevents SMLM from accurately locating fine structures and densely distributed biomolecules within cells. In recent years, nucleic acid probes have emerged as potential tools to replace conventional SMLM probes by virtue of their small size and high specificity. In addition, due to their programmability, nucleic acid probes with different conformations can be constructed via sequence design, further extending the application of SMLM in bioanalysis. Here, we discuss the design concepts of different conformational nucleic acid probes for SMLM and summarize the application of SMLM based on nucleic acid probes in the field of biomolecules. Furthermore, we provide a summary and future perspectives of the nucleic acid probe-based SMLM technology, aiming to provide guidance for the acquisition of nanoscale information about cellular biological processes.

Voltage-controlled bimeron diode-like effect in nanoscale information channel

The magnetic bimeron, as the in-plane counterpart of the magnetic skyrmion, has potential applications in next-generation spin memory devices due to its lower energy consumption. In this work, the dynamic behavior of a current-driven bimeron in a nanotrack with voltage-controlled magnetic anisotropy (VCMA) is investigated. By adjusting the profile of the VCMA, the bimeron can display a diode-like unidirectional behavior in the nanotrack. The unidirectional behavior can be modulated by changing the driven current density and width of the VCMA region. The trajectory of the bimeron can also be controlled by the periodic VCMA region, which can enhance the stability of bimeron and realize a high-storage density bimeron-based information channel.

Generation and routing of nanoscale droplet solitons without compensation of magnetic damping

A magnetic droplet soliton is a localized dynamic spin state which can serve as a nanoscale information carrier and nonlinear oscillator. The present opinion is that the formation of droplet solitons requires the compensation of magnetic damping by a torque created by a spin-polarized electric current or pure spin current. Here, we demonstrate theoretically that nanoscale droplet solitons can be generated and routed in ferromagnetic nanostructures with voltage-controlled magnetic anisotropy in the presence of uncompensated magnetic damping. Performing micromagnetic simulations for the MgO/Fe/MgO trilayer with almost perpendicular-to-plane magnetization, we reveal the formation of the droplet soliton under a nanoscale gate electrode subjected to a subnanosecond voltage pulse. The soliton lives up to 50 ns at room temperature and can propagate over micrometer distances in a ferromagnetic waveguide due to nonzero gradient of the demagnetizing field. Furthermore, we show that electrical routing of the soliton to different outputs of a spintronic device can be realized with the aid of an additional semiconducting nanostripe electrode creating controllable gradient of the perpendicular magnetic anisotropy.

Skyrmions in synthetic antiferromagnets and their nucleation via electrical current and ultra-fast laser illumination

Magnetic skyrmions are topological spin textures that hold great promise as nanoscale information carriers in non-volatile memory and logic devices. While room-temperature magnetic skyrmions and their current-induced motion were recently demonstrated, the stray field resulting from their finite magnetisation and their topological charge limit their minimum size and reliable motion. Antiferromagnetic skyrmions allow to lift these limitations owing to their vanishing magnetisation and net zero topological charge, promising ultra-small and ultra-fast skyrmions. Here, we report on the observation of isolated skyrmions in compensated synthetic antiferromagnets at zero field and room temperature using X-ray magnetic microscopy. Micromagnetic simulations and an analytical model confirm the chiral antiferromagnetic nature of these skyrmions and allow the identification of the physical mechanisms controlling their size and stability. Finally, we demonstrate the nucleation of synthetic antiferromagnetic skyrmions via local current injection and ultra-fast laser excitation.

First-Principles Study of Irn (n = 3-5) Clusters Adsorbed on Graphene and Hexagonal Boron Nitride: Structural and Magnetic Properties.

Magnetic clusters have attracted great attention and interest due to their novel electronic properties, and they have potential applications in nanoscale information storage devices and spintronics. The interaction between magnetic clusters and substrates is still one of the challenging research focuses. Here, by using the density functional theory (DFT), we study the structural stability and magnetic properties of iridium clusters (Irn, n = 3–5) adsorbed on two-dimensional (2D) substrates, such as graphene and hexagonal boron nitride (hBN). We find that the most favorable configurations of free Irn clusters change when adsorbed on 2D substrates. In the meantime, the magnetic moments of the most stable Irn reduce to 53% (graphene) and 23.6% (hBN) compared with those of the free−standing ones. Interestingly, about 12-times enlargement on the magnetic anisotropy energy can be found on hBN substrates. These theoretical results indicate that the cluster–substrate interaction has vital effects on the properties of Irn clusters.

Strain-induced magnetic anisotropy of REIG thin films grown on YAG(111) substrates by pulsed laser deposition

Several studies have revealed using rare earth (RE) elements instead of yttrium to regulate the strain-induced magnetic anisotropy of garnet films in recent years. In this study, we used pulsed laser deposition to fabricate RE iron garnet (REIG) thin films on (111)-oriented yttrium aluminum garnet (YAG) substrates. The REIG films are 100 nm in thickness and crystalline with (111)-orientation. The out-of-plane (444)-plane spacing decreases as the ionic radius of RE metal ions decreases, while the crystallite size increases. Samarium, holmium, and yttrium iron garnet (SmIG, HoIG, and YIG) have out-of-plane compressive strain, while erbium and thulium iron garnet (ErIG and TmIG) have weak out-of-plane tensile strain. The strain of the REIG films is resulted from lattice mismatch, off-stoichiometry, and the recrystallization process by thermal annealing. SmIG has a rather rough surface because of the crystalline distortion due to the largest ionic radius of Sm and the lattice mismatch between SmIG and YAG substrates. Due to negative magnetostriction constant and out-of-plane compressive strain, SmIG and HoIG films show strong perpendicular magnetic anisotropy (PMA) in vibrating sample magnetometry and magneto-optical Faraday effect (MOFE). MOFE also revealed that the REIG films have different sensitivities at different wavelengths of light. With further tuning PMA on SmIG and HoIG by decreasing the thickness and lateral size, our findings could pave the way for high-density nano-scale magnetic information storage based on REIG thin films.

Enhanced circular dichroism of cantilevered nanostructures by distorted plasmon.

Chiral structures have a wide range of applications, such as biometric identification, chemical analysis, and chiral sensing. The simple fabrication process of chiral nanostructures that can produce a significant circular dichroism (CD) effect remains a challenge. Here, a three-dimensional (3D) cantilever-shaped nanostructure, which inherits the chiral advantages of 3D nanostructures and simplicity of 2D nanostructures, is proposed. The nanostructure can be prepared by the combination of one-time electron beam lithography and oblique-angle deposition and consists of a thin metal film with periodic holes such that two hanging arms were attached to the edges of holes. The length of the cantilever and the height difference between the two arms can be adjusted by controlling the tilt angle of beam current during the deposition processes. Numerical calculations showed that the enhancement of CD signal was achieved by plasmon distortion on the metal film by the lower hanging part of the cantilever structure. Furthermore, signals can be actively adjusted using a temperature-sensitive polydimethylsiloxane (PDMS) material. The angle between the lower cantilever and the top metal film was regulated by the change in PDMS volume with temperature. The results provide a new way to fabricating 3D nanostructures and a new mechanism to enhance the CD signal. The proposed nanostructure may have potential applications, such as in ultra-sensitive detection and remote temperature readout, and is expected to be an ultra-compact detection tool for nanoscale structural and functional information.

Discovery of a Dysprosium Metallocene Single-Molecule Magnet with Two High-Temperature Orbach Processes.

Magnetic bistability in single-molecule magnets (SMMs) is a potential basis for new types of nanoscale information storage material. The standard model for thermally activated relaxation of the magnetization in SMMs is based on the occurrence of a single Orbach process. Here, we show that incorporating a phosphorus atom into the framework of the dysprosium metallocene [(CpiPr5)Dy(CpPEt4)]+[B(C6F5)4]− (CpiPr5 is penta-isopropylcyclopentadienyl, CpPEt4 is tetraethylphospholyl) leads to the occurrence of two distinct high-temperature Orbach processes, with energy barriers of 1410(10) and 747(7) cm–1, respectively. These barriers provide experimental evidence for two different spin–phonon coupling regimes, which we explain with the aid of ab initio calculations. The strong and highly axial crystal field in this SMM also allows magnetic hysteresis to be observed up to 70 K, using a scan rate of 25 Oe s–1. In characterizing this SMM, we show that a conventional Debye model and consideration of rotational contributions to the spin–phonon interaction are insufficient to explain the observed phenomena.

Effects of ion adsorption on graphene oxide films and interfacial water structure: A molecular-scale description

Graphene oxide is a promising, emerging separation material, as it is durable, dispersible in water, and has naturally forming functional groups. Bulk studies using graphene oxide flakes have demonstrated impressive metal adsorption. However, little interfacial information about water and metal organization near graphene oxide is available. A mechanistic understanding of water and ions interactions with graphene oxide films is critical toward advanced separations, including improved sorption efficiency and membrane regeneration. We study metal ion and local water organization near graphene oxide thin films formed at the air/water interface. These films are not typical membranes and allow us to determine nanoscale information about the graphene oxide-water interface. We accomplish this with x-ray reflectivity (XR), x-ray fluorescence near total reflection (XFNTR), and vibrational sum frequency generation spectroscopy (SFG). These interface-specific techniques provide the electron density profile normal to the interface, number of adsorbed ions, and information about the orientational ordering and hydrogen-bonding network of interfacial water, respectively. Via XFNTR and SFG, we find that trivalent yttrium ions preferentially adsorb to graphene oxide and affect its structure, compared to divalent strontium and monovalent cesium ions. Two different interfacial water populations can be described, based on their hydrogen bonding strength, and the adsorbed ions affect these populations differently. These results provide fundamental information about ion and water organization at the interface and help address the large computational-experimental agreement gap for graphene oxide systems. Additionally, they are relevant for improved soft-scaffold graphene oxide membranes and downstream applications.

Deterioration Mechanisms and Advanced Inspection Technologies of Aluminum Windows.

Aluminum windows are crucial components of building envelopes since they connect the indoor space to the external environment. Various external causes degrade or harm the functioning of aluminum windows. In this regard, inspecting the performance of aluminum windows is a necessary task to keep buildings healthy. This review illustrates the deterioration mechanisms of aluminum windows under various environmental conditions with an intention to provide comprehensive information for developing damage protection and inspection technologies. The illustrations reveal that moisture and chloride ions have the most detrimental effect on deteriorating aluminum windows in the long run, while mechanical loads can damage aluminum windows in a sudden manner. In addition, multiple advanced inspection techniques potential to benefit assessing aluminum window health state are discussed in order to help tackle the efficiency problem of traditional visual inspection. The comparison among those techniques demonstrates that infrared thermography can help acquire a preliminary defect profile of inspected windows, whereas ultrasonic phased arrays technology demonstrates a high level of competency in analyzing comprehensive defect information. This review also discusses the challenges in the scarcity of nanoscale corrosion information for insightful understandings of aluminum window corrosion and reliable window inspection tools for lifespan prediction. In this regard, molecular dynamics simulation and artificial intelligence technology are recommended as promising tools for better revealing the deterioration mechanisms and advancing inspection techniques, respectively, for future directions. It is envisioned that this paper will help upgrade the aluminum window inspection scheme and contribute to driving the construction of intelligent and safe cities.