Solute Concentration Effects on Microstructure and the Compressive Strength of Ice-Templated Sintered Lithium Titanate

This work investigated the role of sucrose and cationic dispersant (1‐hexadecyl)trimethylammonium bromide concentration on ice‐templated sintered lithium titanate microstructure and compressive strength, to enable a comprehensive understanding of composition selection and elucidate processing–microstructure–mechanical property relationships. Sucrose and dispersant concentrations were varied to change total solute concentration in suspensions and viscosity. Dispersant was more effective in reducing viscosity than sucrose; however, their combination had an even greater impact on reducing viscosity. Based on viscosity measurements, a total of 12 suspension compositions were developed, and materials were fabricated at two different freezing front velocity (FFV) regimes. Solute concentration greatly influenced ice‐templated microstructure and microstructure development improved with solute concentration. Depending on solute concentration, type of solute, viscosity, and FFV, a wide variety of microstructures were observed ranging from lamellar to dendritic morphologies. Solute concentration effect was rationalized based on solid–liquid planar interface instability. For suspensions with comparable viscosity, solute concentration can be varied to tune microstructure, whereas for suspensions with comparable solute concentration, viscosity variation can tune microstructure. Compressive strength of sintered materials generally increased with total solute concentration, sucrose concentration, viscosity, and FFV. Due to the wide variety of microstructure, strength also varied over a wide range, 23–128 MPa

Impact of carbon coating processing using sucrose for thick binder-free titanium niobium oxide lithium-ion battery anode

Lithium-ion batteries are increasingly important for providing energy storage solutions. In the drive to improve the energy density at the cell level, optimizing the electrode architecture is crucial in addition to researching new materials. Binder-free (BF) electrodes include porous pellets only containing battery electroactive materials. These electrodes can provide advantages with regard to mechanical stability and alleviated ion transport limitations relative to composite approaches for very thick and energy-dense electrodes. However, the absence of conductive additives often limits suitable material candidates for BF battery electrodes. TiNb2O7 (TNO) is a promising BF electrode material from a gravimetric and volumetric capacity standpoint, but phase pure TNO has relatively low electronic conductivity. Herein, a sucrose precursor coating method for TNO materials was implemented to process the TNO materials into BF electrodes. The sucrose served as a source to generate carbon in the electrodes, where the carbon coating resulted in an increase in rate capability, discharge voltage, and cycle life

Src Family Kinases Facilitate the Crosstalk between CGRP and Cytokines in Sensitizing Trigeminal Ganglion via Transmitting CGRP Receptor/PKA Pathway

The communication between calcitonin gene-related peptide (CGRP) and cytokines plays a prominent role in maintaining trigeminal ganglion (TG) and trigeminovascular sensitization. However, the underlying regulatory mechanism is elusive. In this study, we explored the hypothesis that Src family kinases (SFKs) activity facilitates the crosstalk between CGRP and cytokines in sensitizing TG. Mouse TG tissue culture was performed to study CGRP release by enzyme-linked immunosorbent assay, cytokine release by multiplex assay, cytokine gene expression by quantitative polymerase chain reaction, and phosphorylated SFKs level by western blot. The results demonstrated that a SFKs activator, pYEEI (YGRKKRRQRRREPQY(PO3H2)EEIPIYL) alone, did not alter CGRP release or the inflammatory cytokine interleukin-1β (IL-1β) gene expression in the mouse TG. In contrast, a SFKs inhibitor, saracatinib, restored CGRP release, the inflammatory cytokines IL-1β, C-X-C motif ligand 1, C-C motif ligand 2 (CCL2) release, and IL-1β, CCL2 gene expression when the mouse TG was pre-sensitized with hydrogen peroxide and CGRP respectively. Consistently with this, the phosphorylated SFKs level was increased by both hydrogen peroxide and CGRP in the mouse TG, which was reduced by a CGRP receptor inhibitor BIBN4096 and a protein kinase A (PKA) inhibitor PKI (14-22) Amide. The present study demonstrates that SFKs activity plays a pivotal role in facilitating the crosstalk between CGRP and cytokines by transmitting CGRP receptor/PKA signaling to potentiate TG sensitization and ultimately trigeminovascular sensitization

Pore Microstructure Impacts on Lithium Ion Transport and Rate Capability of Thick Sintered Electrodes

Increasing electrode thickness is one route to improve the energy density of lithium-ion battery cells. However, restricted Li+ transport in the electrolyte phase through the porous microstructure of thick electrodes limits the ability to achieve high current densities and rates of charge/discharge with these high energy cells. In this work, processing routes to mitigate transport restrictions were pursued. The electrodes used were comprised of only active material sintered together into a porous pellet. For one of the electrodes, comparisons were done between using ice-templating to provide directional porosity and using sacrificial particles during processing to match the geometric density without pore alignment. The ice-templated electrodes retained much greater discharge capacity at higher rates of cycling, which was attributed to improved transport properties provided by the processing. The electrodes were further characterized using an electrochemical model of the cells evaluated and neutron imaging of a cell containing the ice-templated pellet. The results indicate that significant improvements can be made to electrochemical cell properties via templating the electrode microstructure for situations where the rate limiting step includes ion transport limitations in the cell

Selective Hydrogenation of Adiponitrile to 6-Aminocapronitrile over Ni/α-Al₂O₃ Catalysts Doped with K₂O and La₂O₃

A series of Ni/Al2O3, Ni/K2O-Al2O3 and Ni/La2O3-K2O-Al2O3 catalysts that possess high activities for partial hydrogenation of adiponitrile to 6-aminocapronitrile has been successfully synthesized by the impregnation method. The catalytic performance was investigated under atmospheric pressure and in the absence of ammonia and a significant enhancement in the activity after the introduction of potassium oxide and lanthana was observed. Aiming to study the influence of K2O and La2O3 promoters on the physicochemical properties, we characterized the catalysts by N2 adsorption/desorption, XRD, H2-TPR, H2-chemisorption, H2-TPD and TEM techniques. A combination of XRD, TEM and H2-chemisorption showed that Ni0 particles with a higher dispersion are obtained after the addition of La2O3. Compared with the Ni/Al2O3 catalyst, the Ni/La2O3-K2O-Al2O3 catalyst with an appropriate amount of promoter enjoys a more catalyst surface alkalescence, enhances the electronic density of nickel and higher dispersion of nickel and exhibits higher activity and 6-aminocapronitrile selectivity than Ni/α-Al2O3 during the hydrogenation of adiponitrile in the absence of ammonia, i.e., K2O and La2O3 improved the performance of the nickel-based catalyst

Fabrication of ZnO@Plant Polyphenols/Cellulose as Active Food Packaging and Its Enhanced Antibacterial Activity

To investigate the efficient use of bioresources and bioproducts, plant polyphenol (PPL) was extracted from larch bark and further applied to prepare ZnO@PPL/Cel with cellulose to examine its potential as an active package material. The structure and morphology were fully characterized by XRD, SEM, FTIR, XPS and Raman spectra. It was found that PPL is able to cover ZnO and form a coating layer. In addition, PPL cross-links with cellulose and makes ZnO distribute evenly on the cellulose fibers. Coating with PPL creates a pinecone-like morphology in ZnO, which is constructed by subunits of 50 nm ZnO slices. The interactions among ZnO, PPL and cellulose have been attributed to hydrogen bonding, which plays an important role in guiding the formation of composites. The antibacterial properties against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) were tested by the inhibition zone method. Our composite ZnO@PPL/Cel has superior antibacterial activity compared to ZnO/Cel. The antibacterial mechanism has also been elaborated on. The low cost, simple preparation method and good performance of ZnO@PPL/Cel suggest the potential for it to be applied as active food packaging

The Regulation of ROS- and BECN1-Mediated Autophagy by Human Telomerase Reverse Transcriptase in Glioblastoma

Glioblastoma (GBM) is the most common and aggressive malignant brain tumor with high morbidity and mortality. Human telomerase reverse transcriptase (hTERT), the catalytic subunit of human telomerase, is overexpressed in most cancers including GBM. It is well known that hTERT can compensate telomere shortening to immortalize cells. However, in addition to the canonical function, hTERT has the roles beyond canonical telomere maintenance. To further understand the effects of hTERT on glioblastoma progression, we investigated the role of hTERT in regulating autophagy—a conserved pathway, by which cells deliver cellular organic material and impaired organelles to the lysosomes for degradation and recycle these cargos to produce energy under a stressful condition. Our results showed that downregulation of hTERT impaired autophagy levels by suppressing BECN1/beclin-1 and induced an increase of reactive oxygen species (ROS), which resulted in cell death ultimately. On the contrary, overexpression of BECN1 or treating cells with the antioxidant N-acetylcysteine (NAC) could restore the survival of hTERT knockdown cells. Our study will provide an additional basis of telomerase-targeting therapy for future clinical anticancer treatment

Differences in responses to X-ray exposure between osteoclast and osteoblast cells

Radiation-induced bone loss is a potential health concern for cancer patients undergoing radiotherapy. Enhanced bone resorption by osteoclasts and decreased bone formation by osteoblasts were thought to be the main reasons.In this study, we showed that both pre-differentiating and differentiating osteoclasts were relatively sensitive to X-rays compared with osteoblasts. X-rays decreased cell viability to a greater degree in RAW264.7 cells and in differentiating cells than than in osteoblastic MC3T3-E1 cells. X-rays at up to 8 Gy had little effects on osteoblast mineralization. In contrast, X-rays at 1 Gy induced enhanced osteoclastogenesis by enhanced cell fusion, but had no effects on bone resorption. A higher dose of X-rays at 8 Gy, however, had an inhibitory effect on bone resorption. In addition, actin ring formation was disrupted by 8 Gy of X-rays and reorganized into clusters. An increased activity of Caspase 3 was found after X-ray exposure. Actin disorganization and increased apoptosis may be the potential effects of X-rays at high doses, by inhibiting osteoclast differentiation. Taken together, our data indicate high radiosensitivity of osteoclasts. X-ray irradiation at relatively low doses can activate osteoclastogenesis, but not osteogenic differentiation. The radiosensitive osteoclasts are the potentially responsive cells for X-ray-induced bone loss.KEYWORDS: ionizing radiation, osteoblasts, osteoclasts, differentiatio

A gel microparticle-based self-thickening strategy for 3D printing high-modulus hydrogels skeleton cushioned with PNAGA hydrogel mimicking anisotropic mechanics of meniscus

Developing a meniscus substitute mimicking the anisotropic mechanics (higher circumferential tensile modulus and lower compressive modulus) of native tissue remains a great challenge. In this work, based on the pendant group structure-dependent H-bonding strengthening mechanism, two kinds of amide-based H-bonding crosslinked hydrogels with distinct mechanical behaviors, that is, the flexible poly(N-acryloyl glycinamide) (PNAGA) and the ultra-stiff poly(N-acryloylsemicarbazide) (PNASC) hydrogels are employed to construct the biomimetic meniscus substitute. To this end, a gel microparticle-based self-thickening strategy is first proposed to fabricate PNASC (GMP-PNASC) high-modulus hydrogels skeleton by extrusion printing technology in mimicking the collagen fibers in native meniscus to resist the circumferential tensile stress. Then, the PNAGA hydrogel is infused into the PNASC skeleton to replicate the proteoglycan, providing a lower compressive modulus. By regulating the structural features at the interior and peripheral regions, the GMP-PNASC/PNAGA hydrogel meniscus scaffold with the higher tensile modulus (87.28 ± 6.06 MPa) and lower compressive modulus (2.11 ± 0.28 MPa) can be constructed. In vivo outcome at 12 weeks post-implantation of rabbit's medial meniscectomy model confirms the effects of GMP-PNASC/PNAGA meniscus scaffold on alleviating the wear of articular cartilage and ameliorating the development of osteoarthritis (OA)