Nanocrystalline Composite Layer Realized by Simple Sintering Without Surface Treatment, Reducing Hydrophilicity and Increasing Thermal Conductivity.

The surface treatment for a polymer-ceramic composite is additionally performed in advanced material industries. To prepare the composite without a surface treatment, the simplest way to manufacture an advanced ceramic-particle is devised. The method is the formation of a nanocrystalline composite layer through the simple liquid-phase sintering. Using magnesia (MgO) which shows hydrophilicity, a nanocrystalline surface layer is realized by liquid-phase sintering. The amorphous matrix of nanocrystalline composite layer makes MgO hydrophobic and ensures miscibility with polymers, and the nanocrystalline MgO ensures high thermal conductivity. In addition, the liquid phase removes the open pores and makes the surface morphology smooth MgO with smooth surface (MgO-SM). Thermal interface materials (TIM) prepared with MgO-SM and epoxy show a high thermal conductivity of ≈7.5 W m-1 K-1 , which is significantly higher than 4.5 W m-1 K-1 of pure MgO TIM. Consequently, the formation process of a nanocrystalline surface layer utilizing simple liquid-phase sintering is proposed as a fabrication method for a next-generation ceramic-filler. In addition, it is fundamentally identified that the thermal conductivity of MgO depends on the Mg deficiency, and therefore a poly-crystal MgO-SM (produced at a low temperature) has a higher thermal conductivity than a single-crystal MgO (produced at a high temperature).

Molten-Salt Processed Potassium Sodium Niobate Single-Crystal Microcuboids with Dislocation-Induced Nanodomain Structures and Relaxor Ferroelectric Behavior.

We herein report a facile molten-salt synthetic strategy to prepare transparent and uniform Li, Ba-doped (K,Na)NbO3 (KNN) single-crystal microcuboids (∼80 µm). By controlling the degree of supersaturation, different growth modes were found and the single-crystal microcuboids were synthesized via island-like oriented attachment of KNN particles onto the growing surface. The distinct relaxor ferroelectric (RFE) properties were achieved in the single-crystal microcuboids, which were different from the normal ferroelectric (FE) properties found in their KNN ceramic counterparts prepared through a solid-state reaction using the same initial precursors. The RFE properties were realized by dislocation-induced nanodomain formation during oriented attachment growth of single-crystal microcuboids, which is different from the current strategies to derive the nanodomains by the local compositional inhomogeneity or the application of an electric field. The dislocations served as nucleation sites for ferroelectric domain walls and block the growth of domains. The KNN single-crystal microcuboids exhibited a higher effective piezoelectric coefficient (∼459 pm/V) compared to that of the bulk KNN ceramic counterpart (∼90 pm/V) and showed the broad diffuse maxima in the temperature dependence dielectric permittivity. The high maximum polarization (69.6 µC/cm2) at a relatively low electric field (30 kV/cm) was beneficial for energy storage applications. Furthermore, the KNN-based transparent, flexible pressure sensor directly monitored the mechanical motion of human activity without any external electric power. This study provides insights and synthetic strategies of single-crystal RFE microcuboids for other different perovskites, in which nanodomain structures are primarily imposed by their chemical composition.

Effect of Cathode Microstructure on Electrochemical Properties of Sodium Nickel-Iron Chloride Batteries.

Sodium metal chloride batteries have become a substantial focus area in the research on prospective alternatives for battery energy storage systems (BESSs) since they are more stable than lithium ion batteries. This study demonstrates the effects of the cathode microstructure on the electrochemical properties of sodium metal chloride cells. The cathode powder is manufactured in the form of granules composed of a metal active material and NaCl, and the ionic conductivity is attained by filling the interiors of the granules with a second electrolyte (NaAlCl4). Thus, the microstructure of the cathode powder had to be optimized to ensure that the second electrolyte effectively penetrated the cathode granules. The microstructure was modified by selecting the NaCl size and density of the cathode granules, and the resulting Na/(Ni,Fe)Cl2 cell showed a high capacity of 224 mAh g-1 at the 100th cycle owing to microstructural improvements. These findings demonstrate that control of the cathode microstructure is essential when cathode powders are used to manufacture sodium metal chloride batteries.

Therapeutic Efficacy of Artificial Skin Produced by 3D Bioprinting.

The skin protects the body from external barriers. Certain limitations exist in the development of technologies to rapidly prepare skin substitutes that are therapeutically effective in surgeries involving extensive burns and skin transplantation. Herein, we fabricated a structure similar to the skin layer by using skin-derived decellularized extracellular matrix (dECM) with bioink, keratinocytes, and fibroblasts using 3D-printing technology. The therapeutic effects of the produced skin were analyzed using a chimney model that mimicked the human wound-healing process. The 3D-printed skin substitutes exhibited rapid re-epithelialization and superior tissue regeneration effects compared to the control group. These results are expected to aid the development of technologies that can provide customized skin-replacement tissues produced easily and quickly via 3D-printing technology to patients.

Supraparticle Engineering for Highly Dense Microspheres: Yttria-Stabilized Zirconia with Adjustable Micromechanical Properties.

Various supraparticles have been extensively studied owing to their excellent catalytic properties that are attributed to their inherent porous structure; however, their mechanical properties have not garnered attention owing to their less dense structure. We demonstrate a rational approach for fabricating assembled supraparticles and, subsequently, highly dense microspheres. In addition, 3 mol % yttria-stabilized zirconia (3YSZ) and alumina particles were selected as building blocks and assembled into higher-order architectures using a droplet-based template method (spray drying) for validation with proof-of-concept. Moreover, structural features such as density, size, sphericity, and morphology of supraparticles were controlled by adjusting the competing kinetics occurring between the assembly of building blocks and evaporation of the solvent in the droplets. The preparatory aqueous suspension and process parameters were optimized as well. A detailed understanding of the formation mechanism facilitated the yield of tailor-made supraparticles and, thereafter, highly dense microspheres (approximate relative density = 99%) with excellent sphericity (>98%) via heat treatment. The microspheres displayed highest hardness (26.77 GPa) and superior elastic modulus (210.19 GPa) compared with the mechanical properties of the 3YSZ samples reported to date. Ultimately, the proposed supraparticle engineering provided insight for controlling the structural features and resultant micromechanical properties, which widely extends the applicability of supraparticle-based functional materials for practical purposes that require materials with high density and excellent mechanical properties.

High Magnetic Field Sensitivity in Ferromagnetic-Ferroelectric Composite with High Mechanical Quality Factor.

In this study, composite devices were fabricated using ferromagnetic FeSiB-based alloys (Metglas) and ferroelectric ceramics, and their magnetic field sensitivity was evaluated. Sintered 0.95Pb(Zr0.52Ti0.48)O3-0.05Pb(Mn1/3Sb2/3)O3 (PZT-PMS) ceramic exhibited a very dense microstructure with a large piezoelectric voltage coefficient (g31 = -16.8 × 10-3 VmN-1) and mechanical quality factor (Qm > 1600). Owing to these excellent electromechanical properties of the PZT-PMS, the laminate composite with a Metglas/PZT-PMS/Metglas sandwich structure exhibited large magnetoelectric voltage coefficients (αME) in both off-resonance and resonance modes. When the length-to-width aspect ratio (l/w) of the composite was controlled, αME slightly varied in the off-resonance mode, resulting in similar sensitivity values ranging from 129.9 to 146.81 VT-1. Whereas in the resonance mode, the composite with small l/w exhibited a large reduction of αME and sensitivity values. When controlling the thickness of the PZT-PMS (t), the αME of the composite showed the largest value when t was the smallest in the off-resonance mode, while αME was the largest when t is the largest in the resonance mode. The control of t slightly affected the sensitivity in the off-resonance mode, however, higher sensitivity was obtained as t increased in the resonance mode. The results demonstrate that the sensitivity, varying with the dimensional control of the composite, is related to the mechanical loss of the sensor. The composite sensor with the PZT-PMS layer exhibited excellent magnetic field sensitivity of 1.49 × 105 VT-1 with a sub-nT sensing limit, indicating its potential for application in high-performance magnetoelectric sensor devices.

Fecal microbial transplantation and a high fiber diet attenuates emphysema development by suppressing inflammation and apoptosis.

Recent work has suggested a microbial dysbiosis association between the lung and gut in respiratory diseases. Here, we demonstrated that gut microbiome modulation attenuated emphysema development. To modulate the gut microbiome, fecal microbiota transplantation (FMT) and diet modification were adopted in mice exposed to smoking and poly I:C for the emphysema model. We analyzed the severity of emphysema by the mean linear intercept (MLI) and apoptosis by the fluorescent TUNEL assay. Microbiome analysis was also performed in feces and fecal extracellular vesicles (EVs). The MLI was significantly increased with smoking exposure. FMT or a high-fiber diet (HFD) attenuated the increase. Weight loss, combined with smoking exposure, was not noted in mice with FMT. HFD significantly decreased macrophages and lymphocytes in bronchoalveolar lavage fluid. Furthermore, IL-6 and IFN-γ were decreased in the bronchoalveolar lavage fluid and serum. The TUNEL score was significantly lower in mice with FMT or HFD, suggesting decreased cell apoptosis. In the microbiome analysis, Bacteroidaceae and Lachnospiraceae, which are alleged to metabolize fiber into short-chain fatty acids (SCFAs), increased at the family level with FMT and HFD. FMT and HFD attenuated emphysema development via local and systemic inhibition of inflammation and changes in gut microbiota composition, which could provide a new paradigm in COPD treatment.

Selective Phase Control of Dopant-Free Potassium Sodium Niobate Perovskites in Solution.

As one of the perovskite families, potassium sodium niobates (K1-xNax)NbO3 (KNN) have been gaining tremendous attention due to their various functional properties which can be largely determined by their crystallographic phase and composition. However, a selective evolution of different phases for KNN with controlled composition can be difficult to achieve, especially in solution chemical synthesis because of its strong tendency to stabilize into orthorhombic phase at conventional synthetic temperature. We herein developed a facile solution approach to control the phase and composition of dopant-free KNN particles selectively through the modification of reaction parameters. A conventional hydrothermal synthesis method yielded orthorhombic KNN particles, while the monoclinic phase, which has never been observed in a bulk counterpart, was kinetically generated by the compositional modification of an intermediate phase under a high-intensity ultrasound irradiation. Cubic KNN particles were stabilized when ethylene glycol was used as a co-solvent together with deionized water through bonding between ethylene glycol molecules and the surface of the KNN. Composite-structured piezoelectric harvesters were fabricated using each phase of KNN particles and the ß-phase poly(vinylidene fluoride-co-trifluoroethylene) polymer. Maximum output power was found for the harvester containing orthorhombic KNN particles. This facile synthetic methodology could pave a new pathway for fabricating numerous phase-controlled materials.

Lotus seedpod-inspired hydrogels as an all-in-one platform for culture and delivery of stem cell spheroids.

3D culture of stem cells can improve therapeutic effects. However, there is limited research on how to deliver cultured stem cell spheroids to the desired target. Here, we developed lotus seedpod-inspired hydrogel (LoSH) containing microwells for culture and delivery of stem cell spheroids. Human adipose-derived stem cells (hADSCs) inside the square microwells (200 or 400 µm in width with various depths) spontaneously formed spheroids with high viability (94.08 ±â€¯1.56%), and fibronectins conjugated to the hydrogel successfully gripped the spheroids, similar to the funiculus gripping seeds in the lotus seedpod. The spheroids slightly bound to the LoSH surface at 37 °C were detached by the expansion of LoSH at lower temperature of 4 °C. After spheroid formation, LoSH was placed on the target substrate upside-down, expanded at 4 °C for 10 min, and removed from the target. As a result, the spheroids within the microwell were successfully transferred to the target substrate with high transfer efficiency (93.78 ±â€¯2.30%). A delivery of spheroids from LoSH to full-thickness murine skin wound with chimney model showed significant enhancement of the number of SMA-positive vessels at day 21 compared to the group received the same number of spheroids by injection. Together, our findings demonstrate LoSH as a one-step platform that can culture and deliver spheroids to a large target area, which will be useful for various biomedical applications.

Reproducible hindlimb ischemia model based on photochemically induced thrombosis to evaluate angiogenic effects.

Critical limb ischemia is one of the most common types of peripheral arterial disease. Preclinical development of ischemia therapeutics relies on the availability of a relevant and reproducible in vivo disease model. Thus, establishing appropriate animal disease models is essential for the development of new therapeutic strategies. Currently, the most commonly employed model of hindlimb ischemia is the surgical induction method with ligation of the femoral artery and its branches after skin incision. However, the efficiency of the method is highly variable depending on the availability of skilled technicians. In addition, after surgical procedures, animals can quickly and spontaneously recover from damage, limiting observations of the therapeutic effect of potential agents. The aim of this study was to develop a hindlimb ischemia mouse model with similarities to human ischemic disease. To that end, a photochemical reaction was used to induce thrombosis in the hindlimb. After the photochemical reaction was induced by light irradiation, thrombotic plugs and adjacent red blood cell stasis were observed in hindlimb vessels in the light-irradiated zone. Additionally, the photochemically induced thrombosis maintained the ischemic condition and did not cause notable side effects in mice.

Dual stem cell therapy synergistically improves cardiac function and vascular regeneration following myocardial infarction.

Since both myocardium and vasculature in the heart are excessively damaged following myocardial infarction (MI), therapeutic strategies for treating MI hearts should concurrently target both so as to achieve true cardiac repair. Here we demonstrate a concomitant method that exploits the advantages of cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CMs) and human mesenchymal stem cell-loaded patch (hMSC-PA) to amplify cardiac repair in a rat MI model. Epicardially implanted hMSC-PA provide a complimentary microenvironment which enhances vascular regeneration through prolonged secretion of paracrine factors, but more importantly it significantly improves the retention and engraftment of intramyocardially injected hiPSC-CMs which ultimately restore the cardiac function. Notably, the majority of injected hiPSC-CMs display adult CMs like morphology suggesting that the secretomic milieu of hMSC-PA constitutes pleiotropic effects in vivo. We provide compelling evidence that this dual approach can be a promising means to enhance cardiac repair on MI hearts.

A Comparison Study of Fatigue Behavior of Hard and Soft Piezoelectric Single Crystal Macro-Fiber Composites for Vibration Energy Harvesting.

Designing a piezoelectric energy harvester (PEH) with high power density and high fatigue resistance is essential for the successful replacement of the currently using batteries in structural health monitoring (SHM) systems. Among the various designs, the PEH comprising of a cantilever structure as a passive layer and piezoelectric single crystal-based fiber composites (SFC) as an active layer showed excellent performance due to its high electromechanical properties and dynamic flexibilities that are suitable for low frequency vibrations. In the present study, an effort was made to investigate the reliable performance of hard and soft SFC based PEHs. The base acceleration of both PEHs is held at 7 m/s2 and the frequency of excitation is tuned to their resonant frequency (fr) and then the output power (Prms) is monitored for 107 fatigue cycles. The effect of fatigue cycles on the output voltage, vibration displacement, dielectric, and ferroelectric properties of PEHs was analyzed. It was noticed that fatigue-induced performance degradation is more prominent in soft SFC-based PEH (SS-PEH) than in hard SFC-based PEH (HS-PEH). The HS-PEH showed a slight degradation in the output power due to a shift in fr, however, no degradation in the maximum power was noticed, in fact, dielectric and ferroelectric properties were improved even after 107 vibration cycles. In this context, the present study provides a pathway to consider the fatigue life of piezoelectric material for the designing of PEH to be used at resonant conditions for long-term operation.

Exogenous CLASP2 protein treatment enhances wound healing in vitro and in vivo.

Proliferative and migratory abilities of fibroblasts are essential for wound healing at the skin surface. Cytoplasmic linker-associated protein-2 (CLASP2) was originally found to interact with cytoplasmic linker protein (CLIP)-170. CLASP2 plays an important role in microtubule stabilization and the microtubule-stabilizing activity of CLASP2 depends on its interactions with end binding (EB)-1 and CLIP-170. Although the microtubule-stabilizing role of CLASP2 is well established, the effects of CLASP2 on the migration and proliferation of fibroblasts remain unclear in the context of wound healing. Therefore, we tested the utilization of CLASP2 as a directly applied protein drug to improve wound healing by promoting the migration of effector cells, including skin fibroblasts, to the site of repair or injury using an in vivo excisional wound mouse model and in vitro Hs27 skin fibroblast model. Epidermal growth factor, which is a recognized contributor to cell proliferation and migration, was used as positive control. In vitro and in vivo, CLASP2 treatment significantly enhanced cell migration and accelerated wound closure. Furthermore, in vivo, the CLASP2-treated animal group displayed enhanced epidermal repair and collagen deposition. Next, we studied the mechanism of CLASP2 for wound healing. Increasing the abundance of intracellular free CLASP2 in skin fibroblasts by supplying exogenous CLASP2 seemed to stabilize microtubules through an interaction between CLASP2 and CLIP-170, as well as EB1. Exogenous CLASP2 also showed direct binding with IQGAP1, increasing both cyclic adenosine monophosphate activity and phosphorylation of glycogen synthase kinase 3ß, which in turn reinstated the binding between free CLASP2 and IQGAP1. In summary, exogenous CLASP2 increased Hs27 skin fibroblast migration by interacting with IQGAP1 and other cytoskeletal linker proteins, such as CLIP-170 and EB1. Our results strongly suggest that CLASP2 can be developed in wound healing drugs for skin repair and/or regenerating cosmetic products.

Functional Equivalency in Human Somatic Cell Nuclear Transfer-Derived Endothelial Cells.

The derivation of human embryonic stem cells (hESCs) by somatic cell nuclear transfer (SCNT) has prompted a re-emerging interest in using such cells for therapeutic cloning. Despite recent advancements in derivation protocols, the functional potential of CHA-NT4 derived cells is yet to be elucidated. For this reason, this study sought to differentiate CHA-NT4 cells toward an endothelial lineage in order to evaluate in vitro and in vivo functionality. To initial differentiation, embryoid body formation of CHA-NT4 was mediated by concave microwell system which was optimized for hESC-endothelial cell (EC) differentiation. The isolated CD31+ cells exhibited hallmark endothelial characteristics in terms of morphology, tubule formation, and ac-LDL uptake. Furthermore, CHA-NT4-derived EC (human nuclear transfer [hNT]-ESC-EC) transplantation in hind limb ischemic mice rescued the hind limb and restored blood perfusion. These findings suggest that hNT-ESC-EC are functionally equivalent to hESC-ECs, warranting further study of CHA-NT4 derivatives in comparison to other well established pluripotent stem cell lines. This revival of human SCNT-ESC research may lead to interesting insights into cellular behavior in relation to donor profile, mitochondrial DNA, and oocyte quality. Stem Cells 2019;37:623-630.

Reconstituting Human Cutaneous Regeneration in Humanized Mice under Endothelial Cell Therapy.

Much of our understanding of human biology and the function of mammalian cells in tissue regeneration have been derived from mechanistically and genetically manipulated rodent models. However, current models examining epidermal wound repair fail to address both the cross-species mechanistic and immunogenic differences simultaneously. Herein, we describe a multifaceted approach intended to better recapitulate human skin recovery in rodent models. First, immunodeficient NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ mice were intravenously inoculated with human hematopoietic stem cells to become, in essence, humanized, and capable of initiating an adaptive immune response. Next, a chimney-shaped mechanical device was implanted onto the excisional wound site to prevent healing by primary intention (contraction) and expedite cell transplantation. Subsequently, cell therapy was administered by transplanting cord blood-derived endothelial progenitor cells or human pluripotent stem cell-derived endothelial cells into the wound site to examine the regeneration process at a histological level. This study demonstrates human cutaneous repair in a murine model by addressing both the mechanistic and immunogenic differences in the epidermis. We further show human leukocyte recruitment in damaged tissue and improved healing by secondary intention in the transplanted groups, highlighting the need for useful preclinical animal models to better understand leukocyte function in human (tissue repair and) regeneration.

Enhancement of Magnetoelectric Conversion Achieved by Optimization of Interfacial Adhesion Layer in Laminate Composites.

We report the effect of epoxy adhesion layers with different mechanical or physical property on a magnetoelectric (ME) composite laminate composed of FeBSi alloy (Metglas)/single-crystal Pb(Mg1/3Nb2/3)O3-Pb(Zr,Ti)O3/Metglas to achieve an improved ME conversion performance. Through theoretical simulation, it was revealed that the Young's modulus and the thickness of interfacial adhesives were major parameters that influence the conversion efficiency in ME composites. In the experimental evaluation, we utilized three epoxy materials with a distinct Young's modulus and adjusted the average thickness of the adhesion layers to optimize the ME conversion. The experimental results show that a thin epoxy layer with a high Young's modulus provided the best performance in the inorganic-based ME conversion process. By tailoring the interfacial adhesion property, the ME laminate generated a high conversion coefficient of 328.8 V/(cm Oe), with a mechanical quality factor of 132.0 at the resonance mode. Moreover, we demonstrated a highly sensitive alternating current magnetic field sensor that had a detection resolution below 10 pT. The optimization of the epoxy layers in the ME laminate composite provided significant enhancement of the ME response in a simple manner.

Dimensional and compositional change of 1D chalcogen nanostructures leading to tunable localized surface plasmon resonances.

As part of the oxygen family, chalcogen (Se, Te) nanostructures have been considered important elements for various practical fields and further exploited to constitute metal chalcogenides for each targeted application. Here, we report a controlled synthesis of well-defined one-dimensional chalcogen nanostructures such as nanowries, nanorods, and nanotubes by controlling reduction reaction rate to fine-tune the dimension and composition of the products. Tunable optical properties (localized surface plasmon resonances) of these chalcogen nanostructures are observed depending on their morphological, dimensional, and compositional variation.

Laser Irradiation of Metal Oxide Films and Nanostructures: Applications and Advances.

Recent technological advances in developing a diverse range of lasers have opened new avenues in material processing. Laser processing of materials involves their exposure to rapid and localized energy, which creates conditions of electronic and thermodynamic nonequilibrium. The laser-induced heat can be localized in space and time, enabling excellent control over the manipulation of materials. Metal oxides are of significant interest for applications ranging from microelectronics to medicine. Numerous studies have investigated the synthesis, manipulation, and patterning of metal oxide films and nanostructures. Besides providing a brief overview on the principles governing the laser-material interactions, here, the ongoing efforts in laser irradiation of metal oxide films and nanostructures for a variety of applications are reviewed. Latest advances in laser-assisted processing of metal oxides are summarized.

Next Generation Ceramic Substrate Fabricated at Room Temperature.

A ceramic substrate must not only have an excellent thermal performance but also be thin, since the electronic devices have to become thin and small in the electronics industry of the next generation. In this manuscript, a thin ceramic substrate (thickness: 30-70 µm) is reported for the next generation ceramic substrate. It is fabricated by a new process [granule spray in vacuum (GSV)] which is a room temperature process. For the thin ceramic substrates, AlN GSV films are deposited on Al substrates and their electric/thermal properties are compared to those of the commercial ceramic substrates. The thermal resistance is significantly reduced by using AlN GSV films instead of AlN bulk-ceramics in thermal management systems. It is due to the removal of a thermal interface material which has low thermal conductivity. In particular, the dielectric strengths of AlN GSV films are much higher than those of AlN bulk-ceramics which are commercialized, approximately 5 times. Therefore, it can be expected that this GSV film is a next generation substrate in thermal management systems for the high power application.

PRMT8 Controls the Pluripotency and Mesodermal Fate of Human Embryonic Stem Cells By Enhancing the PI3K/AKT/SOX2 Axis.

Basic fibroblast growth factor (bFGF) supplementation is critical to maintain the pluripotency of human pluripotent stem cells (hPSCs) through activation of PI3K/AKT, rather than MEK/ERK pathway. Thus, elaborate molecular mechanisms that preserve PI3K/AKT signaling upon bFGF stimulation may exist in hPSCs. Protein arginine methyltransferase 8 (PRMT8) was expressed and then its level gradually decreased during spontaneous differentiation of human embryonic stem cells (hESCs). PRMT8 loss- or gain-of-function studies demonstrated that PRMT8 contributed to longer maintenance of hESC pluripotency, even under bFGF-deprived conditions. Direct interaction of membrane-localized PRMT8 with p85, a regulatory subunit of PI3K, was associated with accumulation of phosphoinositol 3-phosphate and consequently high AKT activity. Furthermore, the SOX2 induction, which was controlled by the PRMT8/PI3K/AKT axis, was linked to mesodermal lineage differentiation. Thus, we propose that PRMT8 in hESCs plays an important role not only in maintaining pluripotency but also in controlling mesodermal differentiation through bFGF signaling toward the PI3K/AKT/SOX2 axis. Stem Cells 2017;35:2037-2049.