Ingenious Architecture and Coloration Generation in Enamel of Rodent Teeth.

Teeth exemplify architectures comprising an interplay of inorganic and organic constituents, resulting in sophisticated natural composites. Rodents (Rodentia) showcase extraordinary adaptations, with their continuously growing incisors surpassing human teeth in functional and structural optimizations. In this study, employing state-of-the-art direct atomic-scale imaging and nanoscale spectroscopies, we present compelling evidence that the release of material from ameloblasts and the subsequent formation of iron-rich enamel and surface layers in the constantly growing incisors of rodents are complex orchestrated processes, intricately regulated and independent of environmental factors.

Controlled Formation of Nanoribbons and Their Heterostructures via Assembly of Mass-Selected Inorganic Ions.

Control of nanomaterial dimensions with atomic precision through synthetic methods is essential to understanding and engineering of nanomaterials. For single-layer inorganic materials, size and shape controls have been achieved by self-assembly and surface-catalyzed reactions of building blocks deposited at a surface. However, the scope of nanostructures accessible by such approach is restricted by the limited choice of building blocks that can be thermally evaporated onto surfaces, such as atoms or thermostable molecules.

Preparation of High-Quality Samples for MEMS-Based In-Situ (S)TEM Experiments.

A novel focused ion beam (FIB)-based methodology for the preparation of clean and artifact-free specimens on micro-electro-mechanical-system (MEMS)-based chips for in-situ electrical and electro-thermal experiments in a (scanning) transmission electron microscope ((S)TEM) is introduced. Owing to an alternative geometry, the lamellae are attached to a MEMS-based chip directly after the lift-out procedure and afterward further treated or thinned to electron transparency. The quality of produced lamellae on a chip resembles the quality of a classical FIB-prepared sample that is here demonstrated by high-resolution STEM imaging and analytical techniques.

Multi-scale characterization of Developmental Defects of Enamel and their clinical significance for diagnosis and treatment.

Developmental Defects of Enamel (DDE) such as Dental Fluorosis (DF) and Molar Incisor Hypomineralization (MIH) are a major public health problem. Their clinical aspects are extremely variable, challenging their early and specific diagnosis and hindering progresses in restorative treatments. Here, a combination of macro-, micro- and nano-scale structural and chemical methods, including, among others, Atom Probe Tomography recently applied on tooth enamel, were used to study and compare MIH, DF and healthy teeth from 89 patients.

Synthesis, Characterization, and Electronic Properties of ZnO/ZnS Core/Shell Nanostructures Investigated Using a Multidisciplinary Approach.

ZnO/ZnS core/shell nanostructures, which are studied for diverse possible applications, ranging from semiconductors, photovoltaics, and light-emitting diodes (LED), to solar cells, infrared detectors, and thermoelectrics, were synthesized and characterized by XRD, HR-(S)TEM, and analytical TEM (EDX and EELS). Moreover, band-gap measurements of the ZnO/ZnS core/shell nanostructures have been performed using UV/Vis DRS. The experimental results were combined with theoretical modeling of ZnO/ZnS (hetero)structures and band structure calculations for ZnO/ZnS systems, yielding more insights into the properties of the nanoparticles.

Enhanced Pseudo-Capacitive Contributions to High-Performance Sodium Storage in TiO/C Nanofibers via Double Effects of Sulfur Modification.

Pseudo-capacitive mechanisms can provide higher energy densities than electrical double-layer capacitors while being faster than bulk storage mechanisms. Usually, they suffer from low intrinsic electronic and ion conductivities of the active materials. Here, taking advantage of the combination of TiS decoration, sulfur doping, and a nanometer-sized structure, as-spun TiO/C nanofiber composites are developed that enable rapid transport of sodium ions and electrons, and exhibit enhanced pseudo-capacitively dominated capacities.

Metal-Organic Framework-Derived Nanoconfinements of CoF and Mixed-Conducting Wiring for High-Performance Metal Fluoride-Lithium Battery.

Metal fluoride (MF) conversion cathodes theoretically show higher gravimetric and volumetric capacities than Ni- or Co-based intercalation oxide cathodes, which makes metal fluoride-lithium batteries promising candidates for next-generation high-energy-density batteries. However, their high-energy characteristics are clouded by low-capacity utilization, large voltage hysteresis, and poor cycling stability of transition MF cathodes. A variety of reasons is responsible for this: poor reaction kinetics, low conductivities, unstable MF/electrolyte interfaces and dissolution of active species upon cycling.

An optimized TEM specimen preparation method of quantum nanostructures.

Electron transparent TEM lamella with unaltered microstructure and chemistry is the prerequisite for successful TEM explorations. Currently, TEM specimen preparation of quantum nanostructures, such as quantum dots (QDs), remains a challenge. In this work, we optimize the sample-preparation routine for achieving high-quality TEM specimens consisting of SrRuO (SRO) QDs grown on SrTiO (STO) substrates.

Probing Charge Accumulation at SrMnO/SrTiO Heterointerfaces via Advanced Electron Microscopy and Spectroscopy.

The last three decades have seen a growing trend toward studying the interfacial phenomena in complex oxide heterostructures. Of particular concern is the charge distribution at interfaces, which is a crucial factor in controlling the interface transport behavior. However, the study of the charge distribution is very challenging due to its small length scale and the intricate structure and chemistry at interfaces.

Structural, Electronic and Magnetic Properties of a Few Nanometer-Thick Superconducting NdBaCuO Films.

Epitaxial films of high critical temperature ( T c ) cuprate superconductors preserve their transport properties even when their thickness is reduced to a few nanometers. However, when approaching the single crystalline unit cell (u.c.

3D Honeycomb Architecture Enables a High-Rate and Long-Life Iron (III) Fluoride-Lithium Battery.

Metal fluoride-lithium batteries with potentially high energy densities, even higher than lithium-sulfur batteries, are viewed as very promising candidates for next-generation lightweight and low-cost rechargeable batteries. However, so far, metal fluoride cathodes have suffered from poor electronic conductivity, sluggish reaction kinetics and side reactions causing high voltage hysteresis, poor rate capability, and rapid capacity degradation upon cycling. Herein, it is reported that an FeF @C composite having a 3D honeycomb architecture synthesized by a simple method may overcome these issues.

Magnetic Properties of Epitaxially Grown SrRuO Nanodots.

We present the fabrication and exploration of arrays of nanodots of SrRuO with dot sizes between 500 and 15 nm. Down to the smallest dot size explored, the samples were found to be magnetic with a maximum Curie temperature T achieved by dots of 30 nm diameter. This peak in T is associated with a dot-size-induced relief of the epitaxial strain, as evidenced by scanning transmission electron microscopy.

Cross-Linking Hollow Carbon Sheet Encapsulated CuP Nanocomposites for High Energy Density Sodium-Ion Batteries.

Sodium-ion batteries (SIB) are regarded as the most promising competitors to lithium-ion batteries in spite of expected electrochemical disadvantages. Here a "cross-linking" strategy is proposed to mitigate the typical SIB problems. We present a SIB full battery that exhibits a working potential of 3.

Structural optimization and amorphous calcium phosphate mineralization in sensory setae of a terrestrial crustacean (Isopoda: Oniscidea).

Terrestrial isopods possess large sensory setae on their walking legs. Increased fracture resistance of these elongated structures is of crucial importance, making the exoskeleton forming the setae an interesting durable material that may inspire biomimetic designs. We studied the cuticle of the sensory setae with analytical electron microscopy in order to gain detailed insights into its structure and composition at the nanometer scale and identify features that increase the fracture resistance of these minute skeletal elements.

A Sulfur-Limonene-Based Electrode for Lithium-Sulfur Batteries: High-Performance by Self-Protection.

The lithium-sulfur battery is considered as one of the most promising energy storage systems and has received enormous attentions due to its high energy density and low cost. However, polysulfide dissolution and the resulting shuttle effects hinder its practical application unless very costly solutions are considered. Herein, a sulfur-rich polymer termed sulfur-limonene polysulfide is proposed as powerful electroactive material that uniquely combines decisive advantages and leads out of this dilemma.

Correcting the linear and nonlinear distortions for atomically resolved STEM spectrum and diffraction imaging.

Specimen and stage drift as well as scan distortions can lead to a mismatch between true and desired electron probe positions in scanning transmission electron microscopy (STEM) which can result in both linear and nonlinear distortions in the subsequent experimental images. This problem is intensified in STEM spectrum and diffraction imaging techniques owing to the extended dwell times (pixel exposure time) as compared to conventional STEM imaging. As a consequence, these image distortions become more severe in STEM spectrum/diffraction imaging.

Polyphosphate-accumulating bacterial community colonizing the calcium bodies of terrestrial isopod crustaceans Titanethes albus and Hyloniscus riparius.

Terrestrial isopods from the group Trichoniscidae accumulate calcium in specialized organs, known as the calcium bodies. These consist of two pairs of epithelial sacs located alongside the digestive system. These organs contain various forms of calcium and constantly present bacteria.

Magnesium-Assisted Continuous Growth of Strongly Iron-Enriched Incisors.

Teeth are an excellent example where optimally designed nanoarchitectures with precisely constructed components consist of simple compounds. Typically, these simple constituent phases with insignificant properties show mechanical property amplifications when formed into composite architectures. Material properties of functional composites are generally regulated on the nanoscale, which makes their characterization particularly demanding.

Axially aligned organic fibers and amorphous calcium phosphate form the claws of a terrestrial isopod (Crustacea).

Skeletal elements that are exposed to heavy mechanical loads may provide important insights into the evolutionary solutions to mechanical challenges. We analyzed the microscopic architecture of dactylus claws in the woodlice Porcellio scaber and correlated these observations with analyses of the claws' mineral composition with energy dispersive X-ray spectrometry (EDX), electron energy loss spectroscopy (EELS) and selected area electron diffraction (SAED). Extraordinarily, amorphous calcium phosphate is the predominant mineral in the claw endocuticle.

Controlled self-assembly of biomolecular rods on structured substrates.

We report on the evaporative self-assembly and orientational ordering of semi-flexible spherocylindrical M13 phages on asymmetric stranded webs of thin amorphous carbon films. Although the phages were dispersed with a low concentration in the isotropic phase, the substrate edges induced nematic ordering and bending of the phages. As revealed by transmission electron microscopy, phages were aligned parallel to the curved substrate edges.

Massive Dirac Fermion Observed in Lanthanide-Doped Topological Insulator Thin Films.

The breaking of time reversal symmetry (TRS) in three-dimensional (3D) topological insulators (TIs), and thus the opening of a 'Dirac-mass gap' in the linearly dispersed Dirac surface state, is a prerequisite for unlocking exotic physical states. Introducing ferromagnetic long-range order by transition metal doping has been shown to break TRS. Here, we present the study of lanthanide (Ln) doped Bi2Te3, where the magnetic doping with high-moment lanthanides promises large energy gaps.

Adsorption and self-assembly of M13 phage into directionally organized structures on C and SiO2 films.

A versatile method for the directional assembly of M13 phage using amorphous carbon and SiO2 thin films was demonstrated. A high affinity of the M13 phage macromolecules for incorporation into aligned structures on an amorphous carbon surface was observed at the concentration range, in which the viral nanofibers tend to disorder. In contrast, the viral particles showed less freedom to adopt an aligned orientation on SiO2 films when deposited in close vicinity.

Influence of TEM specimen preparation on chemical composition of Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals.

The influences of different transmission electron microscopy (TEM) specimen preparation techniques on the chemical composition of Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) single crystals was studied. Ion-milled samples where no cooling with liquid nitrogen (L-N2) was applied show permanently changed composition also deep inside the bulk material. When the PMN-PT samples were cooled to L-N2 temperature during the ion-milling process and in addition lower accelerating voltages were used, the chemical composition was altered only in the thinnest parts close to the specimen edge.

Microstructure, chemistry, and electronic structure of natural hybrid composites in abalone shell.

The crystal structure and chemical composition at the inorganic/inorganic and inorganic/organic interfaces in abalone shell (genus Haliotis) were investigated using advanced analytical transmission electron microscopy (TEM) methods. Electron energy-loss near-edge structures (ELNES) of Ca-M2,3, C-K, Ca-L2,3, O-K and low-loss EEL spectra acquired from aragonite and calcite are distinctly different. When comparing biogenic with inorganic material for aragonite, only minor differences in C-K fine structures could be detected.