Structure-dependent growth control in nanowire synthesis via on-film formation of nanowires

On-film formation of nanowires, termed OFF-ON, is a novel synthetic approach that produces high-quality, single-crystalline nanowires of interest. This versatile method utilizes stress-induced atomic mass flow along grain boundaries in the polycrystalline film to form nanowires. Consequently, controlling the magnitude of the stress induced in the films and the microstructure of the films is important in OFF-ON. In this study, we investigated various experimental growth parameters such as deposition rate, deposition area, and substrate structure which modulate the microstructure and the magnitude of stress in the films, and thus significantly affect the nanowire density. We found that Bi nanowire growth is favored in thermodynamically unstable films that facilitate atomic mass flow during annealing. A large film area and a large thermal expansion coefficient mismatch between the film and the substrate were found to be critical for inducing large compressive stress in a film, which promotes Bi nanowire growth. The OFF-ON method can be routinely used to grow nanowires from a variety of materials by tuning the material-dependent growth parameters

Influence of Carbon Content and Isothermal Heat Treatment Temperature on the Microstructure and Mechanical Properties of Ultra-High Strength Bainitic Steels

The effect of carbon content and isothermal heat treatment conditions on the microstructure evolution and mechanical properties of ultra-high strength bainitic steels was investigated. A reduction in carbon content from 0.8 wt% to 0.6 wt% in super-bainite steel with typical chemistry effectively improved not only the Charpy impact toughness but also the strength level. This suggests that reducing the carbon content is a very promising way to obtain better mechanical balance between strength and impact toughness. The higher Charpy impact toughness at a lower carbon content of 0.6 wt% is thought to result from a reduction in austenite fraction, and refinement of the austenite grain. The coarse austenite grains have a detrimental effect on impact toughness, by prematurely transforming to deformation-induced martensite during crack propagation. Mechanical properties were also affected by the isothermal treatment temperature. The lower isothermal temperature enhanced the formation of bainitic ferrite with a refined microstructure, which has a beneficial influence on strength, but reduces impact toughness. The lower impact toughness at lower isothermal temperature is attributed to the sluggish redistribution of carbon from the bainitic ferrite into the surrounding austenite. Higher solute carbon in the bainitic ferrite contributes to an increase of strength, but at the same time, encourages a propensity to cleavage fracture.11Ysciescopuskc

Red blood cell trapping using single-beam acoustic tweezers in the Rayleigh regime

Here are the datasets and original code used for the title 'Red blood cell trapping using single-beam acoustic tweezers in the Rayleigh regime.

Switchable preamplifier for dual modal photoacoustic and ultrasound imaging

Photoacoustic (PA) imaging is a high-fidelity biomedical imaging technique based on the principle of molecular-specific optical absorption of biological tissue constitute. Because PA imaging shares the same basic principle as that of ultrasound (US) imaging, the use of PA/US dual-modal imaging can be achieved using a single system. However, because PA imaging is limited to a shallower depth than US imaging due to the optical extinction in biological tissue, the PA signal yields a lower signal-to-noise ratio (SNR) than US images. To selectively amplify the PA signal, we propose a switchable preamplifier for acoustic-resolution PA microscopy implemented on an application-specific integrated circuit. Using the preamplifier, we measured the increments in the SNR with both carbon lead and wire phantoms. Furthermore, in vivo whole-body PA/US imaging of a mouse with a preamplifier showed enhancement of SNR in deep tissues, unveiling deeply located organs and vascular networks. By selectively amplifying the PA signal range to a level similar to that of the US signal without contrast agent administration, our switchable amplifier strengthens the mutual complement between PA/US imaging. PA/US imaging is impending toward clinical translation, and we anticipate that this study will help mitigate the imbalance of image depth between the two imaging modalities. © 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.11Nsciescopu

Collapse pressure measurement of single hollow glass microsphere using single-beam acoustic tweezer

Microbubbles are widely used in medical ultrasound imaging and drug delivery. Many studies have attempted to quantify the collapse pressure of microbubbles using methods that vary depending on the type and population of bubbles and the frequency band of the ultrasound. However, accurate measurement of collapse pressure is difficult as a result of non-acoustic pressure factors generated by physical and chemical reactions such as dissolution, cavitation, and interaction between bubbles. In this study, we developed a method for accurately measuring collapse pressure using only ultrasound pulse acoustic pressure. Under the proposed method, the collapse pressure of a single hollow glass microsphere (HGM) is measured using a high-frequency (20–40 MHz) single-beam acoustic tweezer (SBAT), thereby eliminating the influence of additional factors. Based on these measurements, the collapse pressure is derived as a function of the HGM size using the microspheres’ true density. We also developed a method for estimating high-frequency acoustic pressure, whose measurement using current hydrophone equipment is complicated by limitations in the size of the active aperture. By recording the transmit voltage at the moment of collapse and referencing it against the corresponding pressure, it is possible to estimate the acoustic pressure at the given transmit condition. These results of this study suggest a method for quantifying high-frequency acoustic pressure, provide a potential reference for the characterization of bubble collapse pressure, and demonstrate the potential use of acoustic tweezers as a tool for measuring the elastic properties of particles/cells.11Nsciescopu

Lead-Free Piezoelectric Composite With Lithium Niobate and Barium Titanate Fabricated by Interdigital Pair Bonding Technique

Since 2003, when the European Union (E.U.) announced the restriction of hazardous substances (RoHS), multiple efforts have been made to replace lead zirconate titanate (PZT) based piezoelectric materials. However, despite these efforts, very few PZT alternatives have been found. The Lithium niobate (LN) is one such lead-free piezoelectric material often used in acoustic applications due to its high signal generation efficiency, high curie temperature, and high mechanical Q factor. However, LN is not suitable for miniaturized applications because of its low dielectric constant and high electrical impedance. In this paper, we aim to address the problem of the low-dielectric constant of LN while avoiding hazardous PZT material. We propose to utilize 1–3 composites structure with LN and barium titanate (BT), which has a high dielectric constant while controlling acoustic properties such as density, dielectric constant, sound velocity. We also developed new LN-BT modeling to design piezoelectric composite with interdigital pair bonding (IPB) technique, based on previous PZT-polymer 1–3 composite modeling. We verified that the composite components are lead-free by examining with the scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). This proposed lead-free composite with high-dielectric and lower electrical impedance is better suited for miniaturized applications

Influence of chronological control of transformation on the microstructure and mechanical properties of complex phase steels

We examine the effect of transformation sequence on the microstructure evolution and mechanical prop-erties of complex phase steel consisting of bainite and martensite. Formation of martensite prior to bainite transformation provides uniform lath-type mixture of constituent phases, but preceding isother-mal bainite transformation produces carbon-enriched blocky martensite embedded in the bainite. Even though the presence of carbon-enriched blocky martensite increases the strength of the alloy more effec-tively, the impact toughness is significantly deteriorated with a small fraction of martensite. On the other hand, uniform lath-type mixture of martensite and bainite provides moderate decreased or conserved im-pact toughness at martensite fraction up to 70%, which be considered as an exceedingly beneficial option to enhance the strength of complex phase steel without compromising impact toughness. (c) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.11Nsciescopu

An Exploratory In Vivo Study on the Effect of Annurca Apple Extract on Hair Growth in Mice

Hair loss is an important problem affecting the quality of life in modern society. Recent studies show that Annurca apple extract (AAE), enriched in procyanidin B2 and nutraceuticals, promotes hair growth and induces keratin production. In this study, we investigated the effects of AAE by orally administering AAE in six-week-old C57BL/6 mice once a day for 21 d. We observed improvement in hair length, thickness, weight, and density. The gene expression of two growth factors related to hair growth, vascular endothelial growth factor A (VEGFA) and fibroblast growth factor 7 (FGF-7), were measured using the quantitative reverse transcription polymerase chain reaction (qRT-PCR). The gene expression of both VEGFA and FGF-7 increased significantly in the AAE-treated group. Additionally, treatment with AAE suppressed the gene expression of type 1 5α-reductase. Histological analysis showed that protein levels of cytokeratin 5 and 10 were increased in the skin tissues of the AAE-treated group. These results suggest that AAE might be a potential therapeutic natural product that prevents hair loss by promoting the expression of hair growth-related factors