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Li4Ti5O12 (LTO) is known for its zero-strain characteristic in electrochemical applications, making it a suitable material for fast-charging applications. Here, we systematically studied the quasi-equilibrium and non-equilibrium lithium-ion transportation kinetics in LTO thin-film electrodes, across a range of scales from the crystal lattice to the microstructured electrodes. At the crystal lattice scale, during the non-equilibrium lithiation process, lithium ions are dispersedly embedded into the 16c position, resulting in more 8a → 16c migration compared with the quasi-equilibrium lithiation, and forming numerous fast lithium diffusion channels inside the LTO lattice. At the microstructural electrode scale, optical spectrum characterizations supported the "nano-filaments" lithiation model in polycrystalline LTO thin-film electrodes during the lithiation process. Our results reveal the patterns of lithium migration and distribution within the LTO thin film electrode under the non-equilibrium and quasi-equilibrium lithiation process, offering profound insights into the potential optimization strategies for enhancing the performance of fast-charging thin film batteries. Li4Ti5O12 (LTO) is an ideal battery material for fastcharging applications. The authors examine Li+ transport in LTO thin film electrodes, revealing that nonequilibrium processes result in unique Li+ occupation states that enhance Li+ diffusion. Findings suggests engineering Li+ occupations in LTO crystal lattice can improve battery performance. [ABSTRACT FROM AUTHOR]

Diglyme molecular solvated sodium ion complexes enable the superfast co-intercalation/de-intercalation into graphite interlayers, providing unprecedented prospects for the application of low-dimensional graphitic carbon as fast-charge sodium ion battery anode materials. A thorough understanding of this novel co-intercalation process and resulting solid-electrolyte interphase (SEI) is essential for improving the electrochemical performance of co-intercalation-based high-capacity energy storage systems. This work presents the real-space operando observation of SEI formation and Na-diglyme co-intercalation in the few-layer graphene (FLG) anode as a relevant model of a graphitic anode. The micrometer-sized FLG grid on a nickel current collector was fabricated as a model sample, allowing direct comparative studies using complementary techniques. A reversible sodium-diglyme co-intercalation into the graphene grid was confirmed by Raman spectroscopy, the nanomechanical properties of electrolyte decomposition products on graphene anode and Ni current collector surfaces were studied by ultrasonic force microscopy, and the chemical components of the SEI were confirmed by x-ray photoelectron spectroscopy mapping. We observed a mechanically soft SEI layer formed on the carbon anode surface compared with the electrode current collector surface within the low voltage region (<0.3 V vs Na+/Na), this SEI layer does not affect the reversible Na-diglyme co-intercalations into FLG. At the same time, the SEI layer formed on the Ni current collector mainly contains stiff and thin inorganic species and is electrochemically stable at low voltage regions. Our results clarify the SEI formation behavior on the FLG anode surface in the diglyme electrolyte, providing experimental evidence for the fundamental understanding of Na-diglyme co-intercalation. [ABSTRACT FROM AUTHOR]

To date, there has been limited reporting on the fabrication and properties of macroscopic sheet assemblies (specifically buckypapers) composed of carbon/boron nitride core–shell heteronanotubes (MWCNT@BNNT) or boron nitride nanotubes (BNNTs). Herein we report the synthesis of MWCNT@BNNTs via a facile method involving Atmospheric Pressure Chemical Vapor Deposition (APCVD) and the safe h-BN precursor ammonia borane. These MWCNT@BNNTs were used as sacrificial templates for BNNT synthesis by thermal oxidation of the core carbon. Buckypaper fabrication was facilitated by facile sonication and filtration steps. To test the thermal conductivity properties of these new buckypapers, in the interest of thermal management applications, we have developed a novel technique of advanced scanning thermal microscopy (SThM) that we call piercing SThM (pSThM). Our measurements show a 14% increase in thermal conductivity of the MWCNT@BNNT buckypaper relative to a control multiwalled carbon nanotube (MWCNT) buckypaper. Meanwhile, our BNNT buckypaper exhibited approximately half the thermal conductivity of the MWCNT control, which we attribute to the turbostratic quality of our BNNTs. To the best of our knowledge, this work achieves the first thermal conductivity measurement of a MWCNT@BNNT buckypaper and of a BNNT buckypaper composed of BNNTs not synthesized by high energy techniques. [ABSTRACT FROM AUTHOR]

Mobile edge computing offers ultra-low latency, high bandwidth, and high reliability. Thus, it can support a plethora of emerging services that can be placed in close proximity to the user. One of the fundamental problems in this context is maximizing the benefit from the placement of networked services, while meeting bandwidth and latency constraints. In this study, we propose an adaptive and predictive resource allocation strategy for virtual-network function placement comprising services at the mobile edge. Our study focuses on maximizing the service provider’s benefit under user mobility, i.e., uncertainty. This problem is NP-hard. Therefore, we propose a heuristic solution: we exploit local knowledge about the likely movements of users to speculatively allocate service functions. We allow the service functions to be allocated at different edge nodes, as long as latency and bandwidth constraints are met. We evaluate our proposal against a theoretically optimal algorithm as well as against recent previous work, using widely used simulation tools. Through an extensive simulation study, we demonstrate that under realistic scenarios, an adaptive and proactive strategy coupled with flexible placement can achieve close-to-optimal benefit. [ABSTRACT FROM AUTHOR]

Van der Waals (vdW) atomically thin materials and their heterostructures offer a versatile platform for the management of nanoscale heat transport and the design of novel thermoelectrics. These require the measurement of highly anisotropic heat transport in vdW‐based nanolayers, a major challenge for nanostructured materials and devices. In the present study, a novel effective method of cross‐sectional scanning thermal microscopy was used to map and quantify the anisotropic heat transport in nanoscale thick layers of vdW materials and the material‐substrate interfaces. This technique measures the heat conducted into a vdW crystal via the nanoscale apex of a heat‐sensitive probe. The crystal is nano‐polished via Ar ion beams generating an oblique nearly atomically flat surface. By measuring the thermal conductance variation as a function of increasing layer thickness, the transition between the cross‐plane and in‐plane heat transport (defined by heat conductivity anisotropy) is acquired. By using an analytical model validated by finite element simulations, anisotropic thermal transport in a gamma indium selenide crystal nano‐thin flake on a Si substrate was studied, obtaining results corresponding to anomalously low anisotropic thermal conductivities of kxy = 2.16 Wm−1 K−1 in‐plane and kz = 0.89 Wm−1 K−1 cross‐plane confirming its potential for thermoelectric applications. [ABSTRACT FROM AUTHOR]

The solid electrolyte interphase in rechargeable Li-ion batteries, its dynamics and, significantly, its nanoscale structure and composition, hold clues to high-performing and safe energy storage. Unfortunately, knowledge of solid electrolyte interphase formation is limited due to the lack of in situ nano-characterization tools for probing solid-liquid interfaces. Here, we link electrochemical atomic force microscopy, three-dimensional nano-rheology microscopy and surface force-distance spectroscopy, to study, in situ and operando, the dynamic formation of the solid electrolyte interphase starting from a few 0.1 nm thick electrical double layer to the full three-dimensional nanostructured solid electrolyte interphase on the typical graphite basal and edge planes in a Li-ion battery negative electrode. By probing the arrangement of solvent molecules and ions within the electric double layer and quantifying the three-dimensional mechanical property distribution of organic and inorganic components in the as-formed solid electrolyte interphase layer, we reveal the nanoarchitecture factors and atomistic picture of initial solid electrolyte interphase formation on graphite-based negative electrodes in strongly and weakly solvating electrolytes.Characterization of the solid electrolyte interphase formed on Li-ion battery electrodes presents significant experimental challenges. Here the authors use atomic force microscopy-based force-spectroscopy techniques to depict the initial interphase formation in two different electrolyte classes. [ABSTRACT FROM AUTHOR]

Efficient thermoelectric (TE) conversion of waste heat to usable energy is a holy grail promising to address major societal issues related to energy crisis and global heat management. For these to be economical, synthesis of a solid‐state material with a high figure‐of‐merit (ZT) values is the key, with characterization methods quantifying TE and heat transport properties being indispensable for guiding the development of such materials. In the present study, a large enhancement of the TE power factor in Sb2Te3/MoS2 multilayer structures is reported. A new approach is used to simultaneously experimentally determine the values of in‐plane (kxy) and out‐of‐pane (kz) thermal conductivities for multilayer samples with characteristic layer thickness of few nanometres, essential for the quantification of the ZT, the key parameter for the TE material. Combining simultaneous enhancement in the value of in‐plane power factor (to (4.9 ± 0.4) × mWm−1 K−2) and reduction of the in‐plane value of the thermal conductivity (to 0.7 ± 0.1 Wm−1 K−1) for Sb2Te3/MoS2 multilayer sample led to high values of ZT of 2.08 ± 0.37 at room temperature. The present study, therefore, sets the foundation for a new methodology of exploiting the properties of 2D/3D interfaces for the development of novel fully viable thermoelectric materials. [ABSTRACT FROM AUTHOR]

All-solid-state Li-metal batteries (ASSLBs) are highly desirable, due to their inherent safety and high energy density; however, the irregular and uncontrolled growth of Li filaments is detrimental to interfacial stability and safety. Herein, we report on the incorporation of piezo-/ferroelectric BaTiO3 (BTO) nanofibers into solid electrolytes and determination of electric-field distribution due to BTO inclusion that effectively regulates the nucleation and growth of Li dendrites. Theoretical simulations predict that the piezoelectric effect of BTO embedded in solid electrolyte reduces the driving force of dendrite growth at high curvatures, while its ferroelectricity reduces the overpotential, which helps to regularize Li deposition and Li+ flux. Polarization reversal of soft solid electrolytes was identified, confirming a regular deposition and morphology alteration of Li. As expected, the ASSLBs operating with LiFePO4/Li and poly(ethylene oxide) (PEO)/garnet solid electrolyte containing 10% BTO additive showed a steady and long cycle life with a reversible capacity of 103.2 mAh g-1 over 500 cycles at 1 C. Furthermore, the comparable cyclability and flexibility of the scalable pouch cells prepared and the successful validation in the sulfide electrolytes, demonstrating its universal and promising application for the integration of Li metal anodes in solid-state batteries. [ABSTRACT FROM AUTHOR]

This work investigates a solution process for yttria-stabilized zirconia (YSZ) thin film deposition involving the addition of yttria nanoparticles, at 400 °C, in air. Different yttrium doping levels in the YSZ were studied and a wide range of optical, structural, surface, dielectric, and electronic transport properties were also investigated. An optimum yttrium doping level of 5% mol. resulted in the smoothest films (RRMS ∼ 0.5 nm), a wide bandgap (∼5.96 eV), a dielectric constant in excess of 26, and a leakage current of ∼0.3 nA cm−2 at 2 MV/cm. The solution-processed YSZ films were incorporated as gate dielectrics in thin films transistors with solution-processed In2O3 semiconducting channels. Excellent operational characteristics, such as negligible hysteresis, low operational voltages (5 V), electron mobility in excess of 36 cm2 V−1 s−1, high on/off current modulation ratio on the order of 107, and low interfacial trap density states (<1012 cm−2), were demonstrated. In addition, excellent film homogeneity was achieved over a large area (16 × 16 cm2), with both film thickness and capacitance deviation of <1.2%. [ABSTRACT FROM AUTHOR]

Understanding the fundamentals of surface decoration effects in phase‐separation materials, such as lithium titanate (LTO), is important for optimizing the lithium‐ion battery (LIB) performance. LTO polycrystalline thin‐film electrodes with and without doped Al–ZnO (AZO) surface coating decoration are used as ideal models to gain insights into the mechanisms involved. Operando shear force modulation spectroscopy is used to observe for the first time the nanoscale dynamics of solid‐electrolyte‐interphase (SEI) formation on the electrode surfaces, confirming that the AZO coating is electrochemically converted into a stiff, homogenous SEI layer that protects the surface from the electrolyte‐induced decomposition. This AZO layer and its resultant artificial SEI‐layer have higher Li‐ion transport rates than the unmodified surface. These layers can reduce barriers to surface nucleation and facilitate rapid redistribution of lithium‐ions during the Li4Ti5O12 ⇄ Li7Ti5O12 phase separation, significantly inhabiting the orderly collective phase‐separation behavior (electrochemical oscillation) in the LTO electrode. The suppressed voltage oscillations indicate more homogeneous local exchange current density and de/intercalation states with the decorated electrodes, thereby extending their battery efficiency and long‐term cycling stability. This work highlights the ultimate importance of surface treatment for LIB materials for determining their interfacial chemistry and phase transition during the intercalation/deintercalation. [ABSTRACT FROM AUTHOR]

Traditional sound-absorbing materials have a number of disadvantages: low water resistance, low compressive and tensile strengths, low weather resistance, etc. Therefore, new sound-absorbing materials need to be developed with improved properties including the involvement of industrial byproducts. The influence of the grain-size composition of the rubber crumb from used car tires on the sound insulation of cement and gypsum composites was studied in the paper. The results of the study contribute to the creation of a structural material for the manufacture of sound-absorbing as well as load-bearing structures. The field of application of the developed materials is very extensive. [ABSTRACT FROM AUTHOR]

The ability of a material to conduct heat influences many physical phenomena, ranging from thermal management in nanoscale devices to thermoelectrics. Van der Waals 2D materials offer a versatile platform to tailor heat transfer due to their high surface‐to‐volume ratio and mechanical flexibility. Here, the nanoscale thermal properties of 2D indium selenide (InSe) are studied by scanning thermal microscopy. The high electrical conductivity, broad‐band optical absorption, and mechanical flexibility of 2D InSe are accompanied by an anomalous low thermal conductivity (κ). This can be smaller than that of low‐κ dielectrics, such as silicon oxide, and it decreases with reducing the lateral size and/or thickness of InSe. The thermal response is probed in free‐standing InSe layers as well as layers supported by a substrate, revealing the role of interfacial thermal resistance, phonon scattering, and strain. These thermal properties are critical for future emerging technologies, such as field‐effect transistors that require efficient heat dissipation or thermoelectric energy conversion with low‐κ, high electron mobility 2D materials, such as InSe. [ABSTRACT FROM AUTHOR]

Graphene's (GR) remarkable mechanical and electrical properties—such as its Young's modulus, low mass per unit area, natural atomic flatness and electrical conductance—would make it an ideal material for micro and nanoelectromechanical systems (MEMS and NEMS). However, the difficulty of attaching GR to supports, coupled with naturally occurring internal defects in a few layer GR can significantly adversely affect the performance of such devices. Here, we have used a combined contact resonance atomic force microscopy (CR-AFM) and ultrasonic force microscopy (UFM) approach to characterise and map with nanoscale spatial resolution GR membrane properties inaccessible to most conventional scanning probe characterisation techniques. Using a multi-layer GR plate (membrane) suspended over a round hole, we show that this combined approach allows access to the mechanical properties, internal structure and attachment geometry of the membrane providing information about both the supported and suspended regions of the system. We show that UFM allows the precise geometrical position of the supported membrane-substrate contact to be located and provides an indication of the local variation of its quality in the contact areas. At the same time, we show that by mapping the position sensitive frequency and phase response of CR-AFM response, one can reliably quantify the membrane stiffness, and image the defects in the suspended area of the membrane. The phase and amplitude of experimental CR-AFM measurements show excellent agreement with an analytical model accounting for the resonance of the combined CR-AFM probe-membrane system. The combination of UFM and CR-AFM provide a beneficial combination for the investigation of few-layer NEMS systems based on two dimensional materials. [ABSTRACT FROM AUTHOR]

The open circuit voltage (VOC) is a critical and common indicator of solar cell performance as well as degradation, for panel down to lab-scale photovoltaics. Detecting VOC at the nanoscale is much more challenging, however, due to experimental limitations on spatial resolution, voltage resolution, and/or measurement times. Accordingly, an approach based on Conductive Atomic Force Microscopy is implemented to directly detect the local VOC, notably for monocrystalline Passivated Emitter Rear Contact (PERC) cells which are the most common industrial-scale solar panel technology in production worldwide. This is demonstrated with cross-sectioned monocrystalline PERC cells around the entire circumference of a poly-aluminum-silicide via through the rear emitter. The VOC maps reveal a local back surface field extending ~ 2 μm into the underlying p-type Si absorber due to Al in-diffusion as designed. Such high spatial resolution methods for photovoltaic performance mapping are especially promising for directly visualizing the effects of processing parameters, as well as identifying signatures of degradation for silicon and other solar cell technologies. [ABSTRACT FROM AUTHOR]

Erasure codes in large-scale storage systems allow recovery of data from a failed node. A recently developed class of codes, locally repairable codes (LRCs), offers tradeoffs between storage overhead and repair cost. LRCs facilitate efficient recovery scenarios by adding parity blocks to the system. However, these additional blocks may eventually increase the number of blocks that must be reconstructed. Existing LRCs differ in their use of the parity blocks, in their locality semantics, and in their parameter space. Thus, existing theoretical models cannot directly compare different LRCs to determine which code offers the best recovery performance, and at what cost. We perform the first systematic comparison of existing LRC approaches. We analyze Xorbas, Azure's LRCs, and Optimal-LRCs in light of two new metrics: average degraded read cost and normalized repair cost. We showthe tradeoff between these costs and the code's fault tolerance, and that different approaches offer different choices in this tradeoff. Our experimental evaluation on a Ceph cluster further demonstrates the different effects of realistic system bottlenecks on the benefit from each LRC approach. Despite these differences, the normalized repair cost metric can reliably identify the LRC approach that would achieve the lowest repair cost in each setup. [ABSTRACT FROM AUTHOR]

Biomaterials capable of controlling the delivery of drugs have the potential to treat a variety of conditions. Herein, the preparation of electrically conductive silk fibroin film‐based drug delivery devices is described. Casting aqueous solutions of Bombyx mori silk fibroin, followed by drying and annealing to impart β‐sheets to the silk fibroin, assure that the materials are stable for further processing in water; and the silk fibroin films are rendered conductive by generating an interpenetrating network of a copolymer of pyrrole and 3‐amino‐4‐hydroxybenzenesulfonic acid in the silk fibroin matrix (characterized by a variety of techniques including circular dichroism, Fourier‐transform infrared spectroscopy, nuclear magnetic resonance, Raman spectroscopy, resistance measurements, scanning electron microscopy‐energy dispersive X‐ray spectroscopy, thermogravimetric analysis, X‐ray diffraction, and X‐ray photoelectron spectroscopy). Fibroblasts adhere on the surface of the biomaterials (viability assessed using an (3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide) assay and visualized using a confocal microscope), and a fluorescently labeled drug (Texas‐Red Gentamicin) can be loaded electrochemically and released (µg cm−2 quantities) in response to the application of an electrical stimulus. [ABSTRACT FROM AUTHOR]

The energy dependent thermoelectric response of a single molecule contains valuable information about its transmission function and its excited states. However, measuring it requires devices that can efficiently heat up one side of the molecule while being able to tune its electrochemical potential over a wide energy range. Furthermore, to increase junction stability, devices need to operate at cryogenic temperatures. In this work, we report on a device architecture to study the thermoelectric properties and the conductance of single molecules simultaneously over a wide energy range. We employ a sample heater in direct contact with the metallic electrodes contacting the single molecule which allows us to apply temperature biases up to ΔT = 60 K with minimal heating of the molecular junction. This makes these devices compatible with base temperatures Tbath < 2 K and enables studies in the linear (Δ T ≪ T molecule ) and nonlinear (Δ T ≫ T molecule ) thermoelectric transport regimes. [ABSTRACT FROM AUTHOR]

Presents a study which examined local viscoelastic properties and a micromechanical structure of polymer hydrogel using transmission acoustic microscopy. Link between the mechanical properties of polymers and multiphase polymer systems and its mechanical microstructure; Experimental procedures; Description of the acoustic images of poly(vinylalcohol) gel film; Attenuation measurements for the polymer hydrogel.

The production of helium bubbles in advanced gas-cooled reactor (AGR) cladding could represent a significant hazard for both the mechanical stability and long-term storage of such materials. However, the high radioactivity of AGR cladding after operation presents a significant barrier to the scientific study of the mechanical properties of helium incorporation, said cladding typically being analyzed in industrial hot cells. An alternative non-active approach is to implant He2+ into unused AGR cladding material via an accelerator. Here, a feasibility study of such a process, using sequential implantations of helium in AGR cladding steel with decreasing energy is carried out to mimic the buildup of He (e.g., 50 appm) that would occur for in-reactor AGR clad in layers of the order of 10 µm in depth, is described. The implanted sample is subsequently analyzed by scanning electron microscopy, nanoindentation, atomic force and ultrasonic force microscopies. As expected, the irradiated zones were affected by implantation damage (< 1 dpa). Nonetheless, such zones undergo only nanoscopic swelling and a small hardness increase (~ 10%), with no appreciable decrease in fracture strength. Thus, for this fluence and applied conditions, the integrity of the steel cladding is retained despite He2+ implantation. [ABSTRACT FROM AUTHOR]

Cross-sectional scanning thermal microscopy, gamma indium selenide, nanoscale heat transport, thermal conductivity anisotropy, van der Waals materials In article number 2300081, Sergio Gonzalez-Munoz, Oleg V. Kolosov, and colleagues use cross-sectional scanning thermal microscopy to independently measure the in-plane and cross-plane thermal conductivity in nanoscale flakes of indium selenide. Keywords: cross-sectional scanning thermal microscopy; gamma indium selenide; nanoscale heat transport; thermal conductivity anisotropy; van der Waals materials EN cross-sectional scanning thermal microscopy gamma indium selenide nanoscale heat transport thermal conductivity anisotropy van der Waals materials 1 1 1 06/20/23 20230611 NES 230611 B Quantifying Anisotropic Heat Transport b Atomically thin layers of van der Waals (vdW) materials demonstrate some of the highest and lowest known values of thermal conductivities in a solid material. [Extracted from the article]

We report direct optical observation of cavitation bubbles in liquid helium, both in classical viscous He I and in superfluid He II, close to the $$\lambda $$ -transition. Heterogenous cavitation due to the fast-flowing liquid over the rough surface of prongs of a quartz tuning fork oscillating at its fundamental resonant frequency of $$4\,\mathrm {kHz}$$ occurs in the form of a cluster of small bubbles rapidly changing its size and position. In accord with previous investigators, we find the cavitation threshold lower in He I than in He II. In He I, the detached bubbles last longer than one camera frame (10 ms), while in He II the cavitation bubbles do not tear off from the surface of the fork up to the highest attainable drive. [ABSTRACT FROM AUTHOR]

This work reports on solution processed Nd2O3 thin films that are deposited under ambient conditions at moderate temperatures of about 400 °C and their implementation as gate dielectrics in thin film transistors employing solution processed ZnO semiconducting channels is also demonstrated. The optical, dielectric, electric, structural, surface, and interface properties of Nd2O3 films are investigated using a wide range of characterization techniques that reveal smooth Nd2O3 films of cubic structure, wide bandgap (6 eV), high‐k (11), and low leakage currents (<0.5 nA cm−2). Thin film transistors (TFTs) using ZnO channels show excellent characteristics, such as high electron mobility, in excess of 65 cm2 V−1 s−1, high on/off current ratio in the range between 106 and 107, and negligible hysteresis. The devices demonstrate excellent constant bias stress and air stability air, i.e., only a small decrease of the electron mobility and threshold voltage (<12%). In addition, the excellent uniformity and homogeneity that is demonstrated combined with the relatively low deposition temperature (compared with those used with the vast majority of the vacuum based techniques employed) in ambient air on glass substrates indicates the potential for the rapid development of metal oxide‐based TFTs employing gate dielectrics also grown from solutions at low manufacturing cost. [ABSTRACT FROM AUTHOR]

Microelectromechanical systems (MEMS) are increasingly at our fingertips. To understand and thereby improve their performance, especially given their ever-decreasing sizes, it is crucial to measure their functionality in situ. Atomic force microscopy (AFM) is well suited for such studies, allowing nanoscale lateral and vertical resolution of static displacements, as well as mapping of the dynamic response of these physically actuating microsystems. In this work, the vibration of a tuning fork based viscosity sensor is mapped and compared to model experiments in air, liquid, and a curing collagen gel. The switching response of a MEMS switch with nanosecond time-scale activation is also monitored – including mapping resonances of the driving microcantilever and the displacement of an overhanging contact structure in response to periodic pulsing. Such nanoscale in situ AFM investigations of MEMS can be crucial for enhancing modeling, design, and the ultimate performance of these increasingly important and sophisticated devices. [ABSTRACT FROM PUBLISHER]

We report the self-catalysed growth of InAs nanowires (NWs) on graphite thin films using molecular beam epitaxy via a droplet-assisted technique. Through optimising metal droplets, we obtained vertically aligned InAs NWs with highly uniform diameter along their entire length. In comparison with conventional InAs NWs grown on Si (111), the graphite surface led to significant effects on the NWs geometry grown on it, i.e. larger diameter, shorter length with lower number density, which were ascribed to the absence of dangling bonds on the graphite surface. The axial growth rate of the NWs has a strong dependence on growth time, which increases quickly in the beginning then slows down after the NWs reach a length of approximately 0.8 μm. This is attributed to the combined axial growth contributions from the surface impingement and sidewall impingement together with the desorption of adatoms during the diffusion. The growth of InAs NWs on graphite was proposed following a vapour-solid mechanism. High-resolution transmission electron microscopy reveals that the NW has a mixture of pure zinc-blende and wurtzite insertions. [ABSTRACT FROM AUTHOR]

Nanosecond scale threshold switching is investigated with conducting atomic force microscopy (AFM) for an amorphous GeSe film. Switched bits exhibit 2-3 orders of magnitude variations in conductivity, as demonstrated in phase change based memory devices. Through the nm-scale AFM probe, this crystallization was achieved with pulse durations of as low as 15 ns, the fastest reported with scanning probe based methods. Conductance AFM imaging of the switched bits further reveals correlations between the switched volume, pulse amplitude, and pulse duration. The influence of film heterogeneities on switching is also directly detected, which is of tremendous importance for optimal device performance. [ABSTRACT FROM AUTHOR]

We present an experimental proof of concept of scanning thermal nanoprobes that utilize the extreme thermal conductance of carbon nanotubes (CNTs) to channel heat between the probe and the sample. The integration of CNTs into scanning thermal microscopy (SThM) overcomes the main drawbacks of standard SThM probes, where the low thermal conductance of the apex SThM probe is the main limiting factor. The integration of CNTs (CNT-SThM) extends SThM sensitivity to thermal transport measurement in higher thermal conductivity materials such as metals, semiconductors and ceramics, while also improving the spatial resolution. Investigation of thermal transport in ultra large scale integration (ULSI) interconnects, using the CNT-SThM probe, showed fine details of heat transport in ceramic layers, vital for mitigating electromigration in ULSI metallic current leads. For a few layer graphene, the heat transport sensitivity and spatial resolution of the CNT-SThM probe demonstrated significantly superior thermal resolution compared to that of standard SThM probes achieving 20–30 nm topography and ∼30 nm thermal spatial resolution compared to 50–100 nm for standard SThM probes. The outstanding axial thermal conductivity, a high aspect ratio and robustness of CNTs can make CNT-SThM the perfect thermal probe for the measurement of nanoscale thermophysical properties and an excellent candidate for the next generation of thermal microscopes. [ABSTRACT FROM AUTHOR]

A new approach has been developed for nanoscale conductance mapping (NCM) based on multidimensional atomic force microscopy (AFM) to efficiently investigate the nanoscale electronic properties of heterogeneous surfaces. The technique uses a sequence of conductive AFM images, all acquired in a single area but each with incrementally higher applied voltages. This generates a matrix of current versus voltage (I–V) spectra, providing nanoscale maps of conductance and current nonlinearities with negligible spatial drift. For crystalline and amorphous phases of a GeSe chalcogenide phase change film, conductance and characteristic amorphous phase “turn-on” voltages are mapped with results providing traditional point-by-point I–V measurements, but acquired hundreds of times faster. Although similar to current imaging tunneling spectroscopy in a scanning tunneling microscope, the NCM technique does not require conducting specimens. It is therefore a promising approach for efficient, quantitative electronic investigations of heterogeneous materials used in sensors, resistive memories, and photovoltaics. [ABSTRACT FROM PUBLISHER]

Nanoscale heat transport is of increasing importance as it often defines performance of modern processors and thermoelectric nanomaterials, and affects functioning of chemical sensors and biosensors. Scanning thermal microscopy (SThM) is the leading tool for nanoscale mapping of thermal properties, but it is often negatively affected by unstable tip–surface thermal contacts. While operating SThM in-liquid environment may allow unimpeded thermal contact and open new application areas, it has so far been regarded as impossible due to increased heat dissipation into the liquid, and the perceived reduced spatial thermal resolution. Nevertheless, in this paper we show that such liquid immersion SThM (iSThM) is fully feasible and, while its thermal sensitivity and spatial resolution is somewhat below that of in-air SThM, it has sufficient thermal contrast to detect thermal conductivity variations in few tens of nm thick graphite nanoflake and metal–polymer nanostructured interconnects. Our results confirm that thermal sensing in iSThM can provide nanoscale resolution on the order of 30 nm, that, coupled with the absence of tip snap-in due to the elimination of capillary forces, opens the possibility for nanoscale thermal mapping in liquids, including thermal phenomena in energy storage devices, catalysts and biosystems. [ABSTRACT FROM AUTHOR]

Previously, we have developed a retro-inverso peptide inhibitor (RI-OR2, rGffvlkGr) that blocks the in vitro formation and toxicity of the Ab oligomers which are thought to be a cause of neurodegeneration and memory loss in Alzheimer's disease. We have now attached a retro-inverted version of the HIV protein transduction domain 'TAT' to RI-OR2 to target this new inhibitor (RI-OR2-TAT, Ac-rGffvlkGrrrrqrrkkrGy-NH2) into the brain. Following its peripheral injection, a fluorescein-labelled version of RI-OR2-TAT was found to cross the blood brain barrier and bind to the amyloid plaques and activated microglial cells present in the cerebral cortex of 17-months-old APPswe/PS1ΔE9 transgenic mice. Daily intraperitoneal injection of RI-OR2-TAT (at 100 nmol/kg) for 21 days into 10-months-old APPswe/PS1 ΔE9 mice resulted in a 25% reduction (p<0.01) in the cerebral cortex of Aβ oligomer levels, a 32% reduction (p<0.0001) of β-amyloid plaque count, a 44% reduction (p<0.0001) in the numbers of activated microglial cells, and a 25% reduction (p<0.0001) in oxidative damage, while the number of young neurons in the dentate gyrus was increased by 210% (p<0.0001), all compared to control APPswe/PS1 ΔE9 mice injected with vehicle (saline) alone. Our data suggest that oxidative damage, inflammation, and inhibition of neurogenesis are all a downstream consequence of Aβ aggregation, and identify a novel brain-penetrant retro-inverso peptide inhibitor of Aβ oligomer formation for further testing in humans as a potential disease-modifying treatment for Alzheimer's disease. [ABSTRACT FROM AUTHOR]

In this paper, we present a study of tungsten disulfide (WS2) two-dimensional (2D) crystals, grown on epitaxial Graphene. In particular, we have employed scanning electron microscopy (SEM) and µRaman spectroscopy combined with multifunctional scanning probe microscopy (SPM), operating in peak force–quantitative nano mechanical (PF-QNM), ultrasonic force microscopy (UFM) and electrostatic force microscopy (EFM) modes. This comparative approach provides a wealth of useful complementary information and allows one to cross-analyze on the nanoscale the morphological, mechanical, and electrostatic properties of the 2D heterostructures analyzed. Herein, we show that PF-QNM can accurately map surface properties, such as morphology and adhesion, and that UFM is exceptionally sensitive to a broader range of elastic properties, helping to uncover subsurface features located at the buried interfaces. All these data can be correlated with the local electrostatic properties obtained via EFM mapping of the surface potential, through the cantilever response at the first harmonic, and the dielectric permittivity, through the cantilever response at the second harmonic. In conclusion, we show that combining multi-parametric SPM with SEM and µRaman spectroscopy helps to identify single features of the WS2/Graphene/SiC heterostructures analyzed, demonstrating that this is a powerful tool-set for the investigation of 2D materials stacks, a building block for new advanced nano-devices. [ABSTRACT FROM AUTHOR]

Describes a method for nanometer resolution subsurface imaging with ultrasonic force microscopy. Impact of low-frequency lateral vibration on subsurface feature imaging; Discrimination of subsurface features by regulating vibration force direction; Visibility of stringlike features in the lateral force modulation image.

Nanoscale scanning thermal microscopy (SThM) transport measurements from cryogenic to room temperature on 2D structures with sub 30 nm resolution are reported. This novel cryogenic operation of SThM, extending the temperature range of the sample down to 150 K, yields a clear insight into the nanothermal properties of the 2D nanostructures and supports the model of ballistic transport contribution at the edge of the detached areas of exfoliated graphene which leads to a size‐dependent thermal resistance of the detached material. The thermal resistance of graphene on SiO2 is increased by one order of magnitude by the addition of a top layer of MoS2, over the temperature range of 150–300 K, providing pathways for increasing the efficiency of thermoelectric applications using van der Waals (vdW) materials. Density functional theory calculations demonstrate that this increase originates from the phonon transport filtering in the weak vdW coupling between the layers and the vibrational mismatch between MoS2 and graphene layers. [ABSTRACT FROM AUTHOR]