Effects of production parameters on microstructure and densification of iron/glass syntactic foam by conventional powder metallurgy

Iron and steel matrix syntactic foams have received a lot of attention owing to their high strength, temperature capability, and corrosion resistance. However, high melting point of the iron and steels complicates applications of some conventional production processes. Since few casting methods were proposed to fabricate iron and steel syntactic foams embedded with the ceramic and metal hollow spheres having macro diameters, most of the foams having micro ceramic and glass hollow spheres were fabricated through powder metallurgy (PM) process, which allows reduction of temperature levels by about 30~40% compared to the casting. Metal injection molding (MIM) was mostly used toward the iron and steel matrix foams because of requiring only limited adaptations for switching from making solid parts to syntactic foams and its capabilities for producing various geometries and sizes. However, if the shape allows the production of the part by conventional PM (pressing and sintering), MIM would in most cases be too expensive. To date, detailed fundamental researches on conventional PM process to fabricate the iron or steel syntactic foams have not been reported. Difficulties of the conventional PM process to fabricate the iron and steel syntactic foams are working pressures and temperatures. For compacting powders to make green bodies, high working pressures can assist the densification of the matrix during sintering while this can deform or fracture the hollow spheres embedded. In case of the foams with the glass hollow spheres, softening of the glass occurs at high temperature thus original shape of the hollow spheres cannot be preserved. Therefore, to overcome the difficulties and to produce sound sintered bodies, the investigation on the production parameters of the conventional PM to fabricate the iron and steel syntactic foams is necessary. In this study, the iron/glass hollow spheres syntactic foams were fabricated via the conventional PM process. Fabrications were conducted with considering different production parameters, which included the compaction pressures and sintering temperatures in conjunction with various volume fractions and particle sizes of the hollow spheres. The microstructures and densification behaviors of the fabricated syntactic foams were characterized by X-ray diffraction, optical microscope, scanning electron microscope and energy dispersion spectroscope

Preoperative 18F-Fdg Pet/CT and CT Radiomics for Identifying Aggressive Histopathological Subtypes in Early Stage Lung Adenocarcinoma

Lung adenocarcinoma (ADC) is the most common non-small cell lung cancer. Surgical resection is the primary treatment for early-stage lung ADC while lung-sparing surgery is an alternative for non-aggressive cases. Identifying histopathologic subtypes before surgery helps determine the optimal surgical approach. Predominantly solid or micropapillary (MIP) subtypes are aggressive and associated with a higher likelihood of recurrence and metastasis and lower survival rates. This study aims to non-invasively identify these aggressive subtypes using preoperative 18F-FDG PET/CT and diagnostic CT radiomics analysis. We retrospectively studied 119 patients with stage I lung ADC and tumors ≤ 2 cm, where 23 had aggressive subtypes (18 solid and 5 MIPs). Out of 214 radiomic features from the PET/CT and CT scans and 14 clinical parameters, 78 significant features (3 CT and 75 PET features) were identified through univariate analysis and hierarchical clustering with minimized feature collinearity. A combination of Support Vector Machine classifier and Least Absolute Shrinkage and Selection Operator built predictive models. Ten iterations of 10-fold cross-validation (10 ×10-fold CV) evaluated the model. A pair of texture feature (PET GLCM Correlation) and shape feature (CT Sphericity) emerged as the best predictor. The radiomics model significantly outperformed the conventional predictor SUVmax (accuracy: 83.5% vs. 74.7%, p = 9e-9) and identified aggressive subtypes by evaluating FDG uptake in the tumor and tumor shape. It also demonstrated a high negative predictive value of 95.6% compared to SUVmax (88.2%, p = 2e-10). The proposed radiomics approach could reduce unnecessary extensive surgeries for non-aggressive subtype patients, improving surgical decision-making for early-stage lung ADC patients

Chiral Biomaterials for Nanomedicines: From Molecules to Supraparticles

Chirality, the property whereby an object or a system cannot be superimposed on its mirror image, prevails amongst nature over various scales. Especially in biology, numerous chiral building blocks and chiral-specific interactions are involved in many essential biological activities. Despite the prevalence of chirality in nature, it has been no longer than 70 years since the mechanisms of chiral-specific interactions drew scientific attention and began to be studied. Owing to the advent of chiral-sensitive equipment such as circular dichroism spectrometers or chiral liquid columns for chromatography, it has recently been possible to achieve a deeper understanding of the chiral-specific interactions and consequential impacts on the functionality and efficiency of nanomedicine. From this point of view, it is worthwhile to examine previously reported chiral biomaterials with their compositions and possible applications to achieve new paradigms of biomaterials. This review discusses chiral materials on various scales and their biological applications

A Highly Sensitive and Flexible Capacitive Pressure Sensor Based on a Porous Three-Dimensional PDMS/Microsphere Composite

In recent times, polymer-based flexible pressure sensors have been attracting a lot of attention because of their various applications. A highly sensitive and flexible sensor is suggested, capable of being attached to the human body, based on a three-dimensional dielectric elastomeric structure of polydimethylsiloxane (PDMS) and microsphere composite. This sensor has maximal porosity due to macropores created by sacrificial layer grains and micropores generated by microspheres pre-mixed with PDMS, allowing it to operate at a wider pressure range (~150 kPa) while maintaining a sensitivity (of 0.124 kPa−1 in a range of 0~15 kPa) better than in previous studies. The maximized pores can cause deformation in the structure, allowing for the detection of small changes in pressure. In addition to exhibiting a fast rise time (~167 ms) and fall time (~117 ms), as well as excellent reproducibility, the fabricated pressure sensor exhibits reliability in its response to repeated mechanical stimuli (2.5 kPa, 1000 cycles). As an application, we develop a wearable device for monitoring repeated tiny motions, such as the pulse on the human neck and swallowing at the Adam’s apple. This sensory device is also used to detect movements in the index finger and to monitor an insole system in real-time

Effect of Heat Treatment Condition on Microstructural and Mechanical Anisotropies of Selective Laser Melted Maraging 18Ni-300 Steel

18Ni-300 maraging steel produced by the selective laser melting (SLM) process has a unique microstructure that is different from that of the same alloy processed by conventional methods. In this paper, maraging steels were fabricated by the selective laser melting process and their microstructures and mechanical properties were investigated in terms of post heat treatment conditions. Moreover, the effect of different heat treatments on the mechanical anisotropy was studied in detail. The micro Vickers hardness in the as-built state was around 340 Hv and could be increased to approximately 600 Hv by aging heat treatments. It was found that the solution heat treatment was not necessary to obtain a fully hardened state. From tensile tests of the maraging steels heat treated with different conditions, it was found that the highest strength was achieved by aging and solution treatment (ST) temperatures lower than the commonly used temperatures. In the direction parallel to the laser scanning, the highest ultimate tensile strength was obtained when 450 °C aging was done without solution heat treatment. In the other two directions tested, i.e., directions normal to the building and 45 degrees to the laser scanning direction, the highest tensile strength was obtained when aging was done at 450 °C after 750 °C solution treatment

Magnetogenetics with Piezo1 Mechanosensitive Ion Channel for CRISPR Gene Editing

Regulation of genetic activity in single cells and tissues is pivotal to determine key cellular functions in current biomedicine, yet the conventional biochemical activators lack spatiotemporal precision due to the diffusion-mediated slow kinetics and nonselectivity. Here, we describe a magnetogenetic method for target-specific activation of a clustered regularly interspaced short palindromic repeats (CRISPR) system for the regulation of intracellular proteins. We used magnetomechanical force generated by the magnetic nanostructure to activate pre-encoded Piezo1, the mechanosensitive ion channel, on the target cell. The activated Piezo1 further triggers the intracellular Ca(2+ )signaling pathway, inducing the pre-encoded genes to express genes of interest (GOIs), which is Cas9 protein for the CRISPR regulation of the target proteins. We demonstrated that this magnetogenetic CRISPR system successfully edits the target genome for both in vitro and pseudo-in vivo environments, providing a versatile magnetic platform for remote gene editing of animals with various size scales.11Nsciescopu

Non-contact long-range magnetic stimulation of mechanosensitive ion channels in freely moving animals

Among physical stimulation modalities, magnetism has clear advantages, such as deep penetration and untethered interventions in biological subjects. However, some of the working principles and effectiveness of existing magnetic neurostimulation approaches have been challenged, leaving questions to be answered. Here we introduce m-Torquer, a magnetic toolkit that mimics magnetoreception in nature. It comprises a nanoscale magnetic torque actuator and a circular magnet array, which deliver piconewton-scale forces to cells over a working range of similar to 70 cm. With m-Torquer, stimulation of neurons expressing bona fide mechanosensitive ion channel Piezo1 enables consistent and reproducible neuromodulation in freely moving mice. With its long working distance and cellular targeting capability, m-Torquer provides versatility in its use, which can range from single cells to in vivo systems, with the potential application in large animals such as primates.11Nsciescopu

Hydrogel Magnetomechanical Actuator Nanoparticles for Wireless Remote Control of Mechanosignaling In Vivo

As a new enabling nanotechnology tool for wireless, target-specific, and long-distance stimulation of mechanoreceptors in vivo, here we present a hydrogel magnetomechanical actuator (h-MMA) nanoparticle. To allow both deep-tissue penetration of input signals and efficient force generation, h-MMA integrates a two-step transduction mechanism that converts magnetic anisotropic energy to thermal energy within its magnetic core (i.e., Zn0.4Fe2.6O4 nanoparticle cluster) and then to mechanical energy to induce the surrounding polymer (i.e., pNiPMAm) shell contraction, finally delivering forces to activate targeted mechanoreceptors. We show that h-MMAs enable on-demand modulation of Notch signaling in both fluorescence reporter cell lines and a xenograft mouse model, demonstrating its utility as a powerful in vivo perturbation approach for mechanobiology interrogation in a minimally invasive and untethered manner. © 2023 American Chemical Society.11Nsciescopu

Hydrogel Magnetomechanical Actuator Nanoparticles for Wireless Remote Control of Mechanosignaling In Vivo

As a new enabling nanotechnology tool for wireless, target-specific, and long-distance stimulation of mechanoreceptors in vivo, here we present a hydrogel magnetomechanical actuator (h-MMA) nanoparticle. To allow both deep-tissue penetration of input signals and efficient force generation, h-MMA integrates a two-step transduction mechanism that converts magnetic anisotropic energy to thermal energy within its magnetic core (i.e., Zn0.4Fe2.6O4 nanoparticle cluster) and then to mechanical energy to induce the surrounding polymer (i.e., pNiPMAm) shell contraction, finally delivering forces to activate targeted mechanoreceptors. We show that h-MMAs enable on-demand modulation of Notch signaling in both fluorescence reporter cell lines and a xenograft mouse model, demonstrating its utility as a powerful in vivo perturbation approach for mechanobiology interrogation in a minimally invasive and untethered manner

Preoperative 18F-FDG PET/CT and CT radiomics for identifying aggressive histopathological subtypes in early stage lung adenocarcinoma

Lung adenocarcinoma (ADC) is the most common non-small cell lung cancer. Surgical resection is the primary treatment for early-stage lung ADC while lung-sparing surgery is an alternative for non-aggressive cases. Identifying histopathologic subtypes before surgery helps determine the optimal surgical approach. Predominantly solid or micropapillary (MIP) subtypes are aggressive and associated with a higher likelihood of recurrence and metastasis and lower survival rates. This study aims to non-invasively identify these aggressive subtypes using preoperative 18F-FDG PET/CT and diagnostic CT radiomics analysis. We retrospectively studied 119 patients with stage I lung ADC and tumors ≤ 2 cm, where 23 had aggressive subtypes (18 solid and 5 MIPs). Out of 214 radiomic features from the PET/CT and CT scans and 14 clinical parameters, 78 significant features (3 CT and 75 PET features) were identified through univariate analysis and hierarchical clustering with minimized feature collinearity. A combination of Support Vector Machine classifier and Least Absolute Shrinkage and Selection Operator built predictive models. Ten iterations of 10-fold cross-validation (10 ×10-fold CV) evaluated the model. A pair of texture feature (PET GLCM Correlation) and shape feature (CT Sphericity) emerged as the best predictor. The radiomics model significantly outperformed the conventional predictor SUVmax (accuracy: 83.5% vs. 74.7%, p = 9e-9) and identified aggressive subtypes by evaluating FDG uptake in the tumor and tumor shape. It also demonstrated a high negative predictive value of 95.6% compared to SUVmax (88.2%, p = 2e-10). The proposed radiomics approach could reduce unnecessary extensive surgeries for non-aggressive subtype patients, improving surgical decision-making for early-stage lung ADC patients