Quantitative Measurement of adhesion energy between nanolayers and substrates using a nanowire-supported bridging method

The measurement of adhesion energy between nanolayers and substrates holds significant importance for the design, fabrication, and stability assessment of micro-/nanoscale devices relying on nanolayers. In this study, we propose a nanowire-supported bridging method based on an optical microscope-based nanomanipulation technique to quantitatively measure the adhesion energy between nanolayers and substrates. Using this innovative approach, we conducted adhesion energy measurements between mica nanolayers and Si substrates, revealing a value of approximately 110 J/m2. Additionally, we discuss the applicable conditions of this new method. The proposed technique allows measurements in atmospheric conditions and is, in principle, applicable to all types of nanolayers and substrates. Consequently, it holds promise as a universal method for assessing adhesion energy between nanolayers and substrates, considering environmental factors such as atmosphere and roughness

The kinetic frictional shear stress of ZnO nanowires on graphite and mica substrates

The frictional shear stress between a nanostructure and a smooth substrate plays a crucial role in the development of nanodevices; however, it is extremely difficult to measure. In this work, the kinetic frictional shear stress of hexagonal ZnO nanowires on graphite and mica substrates was measured in an ambient atmosphere by optical microscope based nanomanipulation. Both substrates have similar surface roughness values of sub-angstrom-scale and interfacial adhesion energies with ZnO nanowires. Yet, a kinetic frictional shear stress of 0.51 MPa was obtained for the ZnO-graphite system, significantly lower than that of 5.1 MPa for the ZnO-mica system. The results demonstrate that the kinetic friction at a perfectly smooth contact interface may not be controlled by the adhesion, whilst being commonly referred to as adhesive friction or adhesion-dominated fiction. Similar to the combining equations for adhesion, we propose two empirical combining equations to estimate the frictional shear stress between two smooth surfaces using results more simply obtained from a reference surface. The validity of the equations is supported by our experimental results and recently published data for atomically smooth interface systems obtained under the similar environmental conditions

Big Data Small Data, In Domain Out-of Domain, Known Word Unknown Word: The Impact of Word Representations on Sequence Labelling Tasks

Word embeddings -- distributed word representations that can be learned from unlabelled data -- have been shown to have high utility in many natural language processing applications. In this paper, we perform an extrinsic evaluation of five popular word embedding methods in the context of four sequence labelling tasks: POS-tagging, syntactic chunking, NER and MWE identification. A particular focus of the paper is analysing the effects of task-based updating of word representations. We show that when using word embeddings as features, as few as several hundred training instances are sufficient to achieve competitive results, and that word embeddings lead to improvements over OOV words and out of domain. Perhaps more surprisingly, our results indicate there is little difference between the different word embedding methods, and that simple Brown clusters are often competitive with word embeddings across all tasks we consider

Big Data Small Data, In Domain Out-of Domain, Known Word Unknown Word: The Impact of Word Representations on Sequence Labelling Tasks

Word embeddings — distributed word representations that can be learned from unlabelled data — have been shown to have high utility in many natural language processing applications. In this paper, we perform an extrinsic evaluation of four popular word embedding methods in the context of four sequence labelling tasks:part-of-speech tagging, syntactic chunking, named entity recognition, and multiword expression identification. A particular focus of the paper is analysing the effects of task-based updating of word representations. We show that when using word embeddings as features, as few as several hundred training instances are sufficient to achieve competitive results, and that word embeddings lead to improvements over out-of-vocabulary words and also out of domain. Perhaps more surprisingly, our results indicate there is little difference between the different word embedding methods, and that simple Brown clusters are often competitive with word embeddings across all tasks we conside

High-Dose Dexamethasone Alters the Increase in Interleukin-16 Level in Adult Immune Thrombocytopenia

Adult primary immune thrombocytopenia (ITP) is an autoimmune-mediated haemorrhagic disorder. Interleukin-16 (IL-16) can directly affect cellular or humoural immunity by mediating the cellular cross-talk among T cells, B cells and dendritic cells. Several studies have focused on IL-16 as an immunomodulatory cytokine that takes part in Th1 polarization in autoimmune diseases. In this study, we investigated IL-16 expression in the bone marrow supernatant and plasma of ITP patients and healthy controls. What's more, we detected IL-16 expression in ITP patients with the single-agent 4-day high-dose dexamethasone (HD-DXM) therapy. In patients with active ITP, bone marrow supernatant and plasma IL-16 levels increased (P < 0.05) compared with those of healthy controls. In the meantime, the mRNA expression in BMMCs (pro-IL-16, caspase-3) and PBMCs (pro-IL-16, caspase-3 and T-bet) of ITP patients was increased (P < 0.05) relative to those of healthy controls. In patients who responded to HD-DXM therapy, both plasma IL-16 levels and gene expression in PBMCs (pro-IL-16, caspase-3, and T-bet) were decreased (P < 0.05). In summary, the abnormal level of IL-16 plays important roles in the pathogenesis of ITP. Regulating Th1 polarization associated with IL-16 by HD-DXM therapy may provide a novel insight for immune modulation in ITP

Novel methods for characterising the mechanical properties of nanowhiskers

An loop test was developed for experimentally approaching the theoretical strength of whisker materials. As an example, single-crystal A1O whiskers with diameters in the 82-320 nm range exhibited average fracture strength of 39.1 GPa with a maximum of 48.8 ± 1.8 GPa, which is close to the theoretical prediction of ∼ 46 GPa. A thermal vibration test was developed for accurately determining the modulus of nanowhiskers. As an example, single-crystal W nanobelts with thicknesses down to 65 nm exhibited a size-independent modulus of about 410 GPa, which is close to that of the bulk counterparts

A simple criterion for determining the static friction force between nanowires and flat substrates using the most-bent-state method

A simple criterion was developed to assess the appropriateness of the currently available models that estimate the static friction force between nanowires and substrates using the 'most-bentstate' method. Our experimental testing of the static friction force between Al2O3 nanowires and Si substrate verified our theoretical analysis, as well as the establishment of the criterion. It was found that the models are valid only for the bent nanowires with the ratio of wire length over the minimum curvature radius (L/RO) no greater than 1. For the cases with L/RO greater than 1, the static friction force was overestimated as it neglected the effect of its tangential component

Synthesis of Five-fold-twinned silver microwhiskers by physical vapor deposition

Pentagonal noble metal crystals, with a five-fold-twinned (FFT) structure that exhibits prominent noncrystallographic symmetry, have been the focus of research in the past several decades due to their promising applications in various fields such as chemical and biological sensors, electronics and optoelectronics. A great deal of previous experimental studies and theoretical analyses suggested that such an FFT structure could only exist in the nanoscale crystals, because of the lateral restriction in growth, or in microscale crystals with re-entrant grooves that can effectively release the internal strain. In this study, we synthesized the microscale single-crystalline and multi-twinned Ag crystals with various morphologies, using physical vapor deposition (PVD). FFT Ag microwhiskers with diameters up to 10 μm were produced, but without re-entrant grooves on their side surfaces. Our findings suggest that FFT whiskers can be formed without the use of any surface-capping agents or without necessitating restriction in lateral growth. This further suggests that the current understanding of the surface passivation or the strain-restriction formation of five-fold-twined micro- and nanowhiskers needs improvement

High resolution optical images

Fig.1 (a) The optical image of a NW, sliding on the Si substrate at a constant speed due to the push from a W tip. (b) Mechanical loading model for the sliding NW.Fig.2 The optical images of a NW (a) rest on the Si substrate, (b) being pushed horizontally and bent, (c) being pushed and pressed, and (d) being pulled and pressed by the W tip 1; (e) being pushed and pressed and (f) being pulled and pressed by the W tip 2. The insets in (b)–(e) show the contact configuration between the W tip and the NW, where the arrows describe the direction of the force, F, acted on the NW from the W tip.Fig.3 The bent NW slid on the (a) Si substrate pushed by tip 1, (b) Si substrate pushed by tip 2, and (c) SiN substrate by tip 2. (d) Frictional shear stresses on Si and SiN substrates plotted as a function of the NW length. (e) Roughness of the Si and SiN substrates measured by AFM