Creating Ferromagnetic Insulating La0.9Ba0.1MnO3 Thin Films by Tuning Lateral Coherence Length

In this work, heteroepitaxial vertically aligned nanocomposite (VAN) La0.9Ba0.1MnO3 (LBMO)-CeO2 films are engineered to produce ferromagnetic insulating (FMI) films. From combined X-ray photoelectron spectroscopy, X-ray diffraction and electron microscopy, the elimination of the insulator-metal (I-M) transition is shown to result from the creation of very small lateral coherence lengths (with the corresponding lateral size ~ 3 nm (~ 7 u.c.)) in the LBMO matrix, achieved by engineering a high density of CeO2 nanocolumns in the matrix. The small lateral coherence length leads to a shift in the valence band maximum and reduction of the double exchange (DE) coupling. There is no "dead layer" effect at the smallest lateral coherence length achieved of ~ 3 nm. The FMI behaviour obtained by lateral dimensional tuning is independent of substrate interactions, thus intrinsic to the film itself and hence not related to film thickness. The unique properties of VAN films give the possibility for multilayer spintronic devices that can be made without interface degradation effects between the layers.Royal Academy of Engineering - CIET1819_24, the Leverhulme Trust grant RPG-2015-017, EPSRC grants EP/N004272/1, EP/T012218/1, and EP/M000524/1, the Isaac Newton Trust in Cambridge (minute 16.24(p) and RG96474). EU grant H2020-MSCA-IF-2016 (745886)-MuStMAM

Thin-film design of amorphous hafnium oxide nanocomposites enabling strong interfacial resistive switching uniformity

A design concept of phase-separated amorphous nanocomposite thin films is presented that realizes interfacial resistive switching (RS) in hafnium oxide-based devices. The films are formed by incorporating an average of 7% Ba into hafnium oxide during pulsed laser deposition at temperatures ≤400°C. The added Ba prevents the films from crystallizing and leads to ∼20-nm-thin films consisting of an amorphous HfOx host matrix interspersed with ∼2-nm-wide, ∼5-to-10-nm-pitch Ba-rich amorphous nanocolumns penetrating approximately two-thirds through the films. This restricts the RS to an interfacial Schottky-like energy barrier whose magnitude is tuned by ionic migration under an applied electric field. Resulting devices achieve stable cycle-to-cycle, device-to-device, and sample-to-sample reproducibility with a measured switching endurance of ≥104 cycles for a memory window ≥10 at switching voltages of ±2 V. Each device can be set to multiple intermediate resistance states, which enables synaptic spike-timing-dependent plasticity. The presented concept unlocks additional design variables for RS devices

Mitochondrial DNA Leakage Caused by Streptococcus pneumoniae Hydrogen Peroxide Promotes Type I IFN Expression in Lung Cells

Streptococcus pneumoniae (S. pn), the bacterial pathogen responsible for invasive pneumococcal diseases, is capable of producing substantial amounts of hydrogen peroxide. However, the impact of S. pn-secreted hydrogen peroxide (H2O2) on the host immune processes is not completely understood. Here, we demonstrated that S. pn-secreted H2O2 caused mitochondrial damage and severe histopathological damage in mouse lung tissue. Additionally, S. pn-secreted H2O2 caused not only oxidative damage to mitochondrial deoxyribonucleic acid (mtDNA), but also a reduction in the mtDNA content in alveolar epithelia cells. This resulted in the release of mtDNA into the cytoplasm, which subsequently induced type I interferons (IFN-I) expression. We also determined that stimulator of interferon genes (STING) signaling was probably involved in S. pn H2O2-inducing IFN-I expression in response to mtDNA damaged by S. pn-secreted H2O2. In conclusion, our study demonstrated that H2O2 produced by S. pn resulted in mtDNA leakage from damaged mitochondria and IFN-I production in alveolar epithelia cells, and STING may be required in this process, and this is a novel mitochondrial damage mechanism by which S. pn potentiates the IFN-I cascade in S. pn infection

Downregulation of β-catenin decreases the tumorigenicity, but promotes epithelial-mesenchymal transition in breast cancer cells

Background: Wnt/β-catenin signaling pathway plays a key role in human breast cancer progression. In this study, we down regulated β-catenin expression in human breast cancer MDA-MB-231 cells and investigated the effect of β-catenin knockdown on the cell biological characteristics. Materials and Methods: The recombinant plasmids of pSUPER-enhancement green fluorescent protein 1 (EGFP1)-scrabble-β-catenin-short hairpin ribonucleic acid (shRNA) and pSUPER-EGFP1-β-catenin-shRNA-1 were transfected into MDA-MB-231 cells, respectively, and the stably transfected cells were isolated from G418 selected clones. The β-catenin gene silenced efficiency was measured by quantitative reverse transcriptase polymerase chain reaction (QRT-PCR) and Western blot. The biological characteristics of MDA-MB-231 cells with down regulated β-catenin were evaluated by analyzing cell proliferation, clonogenicity, cell mobility and tumorigenicity. The expression of E-cadherin and Vimentin was concurrently detected by QRT-PCR. Results: The β-catenin-shRNA-1 stably transfected MDA-MB-231 cells significantly decreased β-catenin expression, cell proliferation, clonogenicity, and tumorigenicity in Balb/c nude mice compared with the MDA-MB-231 cells transfected with pSUPER-EGFP1-scrabble-β-catenin-shRNA. Interestingly, knockdown of β-catenin led to the reduction of epithelial E-cadherin expression, the increase of cell mobility and mesenchymal vimentin expression in MDA-MB-231 cells, indicating an epithelial to mesenchymal transition. Conclusion: Knockdown of β-catenin expression in human breast cancer MDA-MB-231 cells inhibits cell tumorigenicity in mice, but promotes cell epithelial-mesenchymal transition

Evaluation of characteristics of CD44⁺CD117⁺ ovarian cancer stem cells in three dimensional basement membrane extract scaffold versus two dimensional monocultures

Abstract Background Cancer stem cells (CSCs) are thought to be capable of surviving conventional chemotherapeutic treatments because the cells have more resistant to anticancer drugs than common cancer cells. Most in vitro studies in experimental cancer cells have been done in a two-dimensional (2D) monocultures, while accumulating evidence suggests that cancer cells behave differently when they are grown within a three-dimensional (3D) culture system. Results The CD44+CD117+cells isolated from human epithelial ovarian cancer SKOV-3 cell line using magnetic-activated cell sorting were found to grow faster than the SKOV-3 cells in the 3D culture and in the nude mice. Anticancer drugs 5FU, docetaxel, cisplatin, and carboplatin were seen to inhibit growth of the CD44+CD117+ cells by 50% in the 2D culture with IC50 concentration, whereas, in the 3D culture, the four drugs inhibited the cell growth by only 34.4%, 40.8%, 34.8% and 21.9% at 3D one, respectively. Effect of paclitaxel on the CD44+CD117+cell viability indicated that fewer cells underwent apoptosis in 3D culture than that in 2D one. In addition, anticancer drugs markedly increased the expression of ABCG2 and ABCB1 of CD44+CD117+cells in 3D culture. Conclusion Our assay demonstrated that human epithelial ovarian cancer CD44+CD117+cells possessed the properties of CSCs that exhibited more chemoresistance in the 3D culture than that of in 2D one. The 3D culture provides a realistic model for study of the CSC response to anticancer drugs.</p

Single-Step Fabrication of Au-Fe-BaTiO₃ Nanocomposite Thin Films Embedded with Non-Equilibrium Au-Fe Alloyed Nanostructures

Nanocomposite thin film materials present great opportunities in coupling materials and functionalities in unique nanostructures including nanoparticles-in-matrix, vertically aligned nanocomposites (VANs), and nanolayers. Interestingly the nanocomposites processed through a non-equilibrium processing method, e.g., pulsed laser deposition (PLD), often possess unique metastable phases and microstructures that could not achieve using equilibrium techniques, and thus lead to novel physical properties. In this work, a unique three-phase system composed of BaTiO3 (BTO), with two immiscible metals, Au and Fe, is demonstrated. By adjusting the deposition laser frequency from 2 Hz to 10 Hz, the phase and morphology of Au and Fe nanoparticles in BTO matrix vary from separated Au and Fe nanoparticles to well-mixed Au-Fe alloy pillars. This is attributed to the non-equilibrium process of PLD and the limited diffusion under high laser frequency (e.g., 10 Hz). The magnetic and optical properties are effectively tuned based on the morphology variation. This work demonstrates the stabilization of non-equilibrium alloy structures in the VAN form and allows for the exploration of new non-equilibrium materials systems and their properties that could not be easily achieved through traditional equilibrium methods

Thin-film design of amorphous hafnium oxide nanocomposites enabling strong interfacial resistive switching uniformity

A design concept of phase-separated amorphous nanocomposite thin films is presented which realizes interfacial resistive switching (RS) in hafnium-oxide-based devices. The films are formed by incorporating an average of 7% Ba into hafnium oxide during pulsed laser deposition at temperatures ≤400 °C. The added Ba prevents the films from crystallizing and leads to ∼20-nm-thin films consisting of an amorphous HfOx host matrix interspersed with ∼2-nmwide, ∼5-to-10-nm-pitch Ba-rich amorphous nanocolumns penetrating ∼2/3 through the films. This restricts the RS to an interfacial Schottky-like energy barrier whose magnitude is tuned by ionic migration under an applied electric field. Resulting devices achieve stable cycle-to-cycle, device-to-device, and sample-to-sample reproducibility with a measured switching endurance of ≥10⁴ cycles for a memory window ≥10 at switching voltages of ±2 V. Each device can be set to multiple intermediate resistance states, which enables synaptic spike-timing-dependent plasticity. The presented concept unlocks additional design variables for RS devices.Cambridge Herchel Smith postdoctoral fellowshi

β-Asarone Induces Apoptosis and Cell Cycle Arrest of Human Glioma U251 Cells via Suppression of HnRNP A2/B1-Mediated Pathway In Vitro and In Vivo

HnRNP A2/B1 has been found to be an oncogenic protein strongly related to the growth of human glioma cells. Herein, &beta;-asarone, the main component in the volatile oil of Acori tatarinowii Rhizoma, inhibited the cell viability, proliferation, and colony formation ability of U251 cells. Moreover, &beta;-asarone induced apoptosis and cell cycle arrest at the G1 phase. Notably, &beta;-asarone suppressed the expression of hnRNP A2/B1 and hnRNPA2/B1 overexpression remarkably reversed &beta;-asarone-mediated apoptosis and cell cycle arrest. Importantly, &beta;-asarone promoted the alternative splicing of Bcl-x by enhancing the ratio of Bcl-xS/Bcl-xL. Meanwhile, hnRNPA2/B1 overexpression mitigated the promoting effect of &beta;-asarone on the alternative splicing of Bcl-x. &beta;-asarone also regulated the level of the key proteins involved in the death receptor pathway and mitochondrial apoptosis pathway. Additionally, &beta;-asarone modulated the cell cycle-related proteins p21, p27, Cdc25A, cyclin D, cyclin E, and CDK2. Finally, &beta;-asarone inhibited tumor growth and induced apoptosis in nude mice bearing U251 tumor xenografts. &beta;-asarone also suppressed the hnRNP A2/B1 expression, enhanced the expression of cleaved-caspase 3 and p27 and the ratio of Bcl-xS/Bcl-xL, and reduced the expression of CDK2 in U251 xenografts. Together, &beta;-asarone-induced apoptosis and cell cycle arrest of U251 cells may be related to the suppression of hnRNPA2/B1-mediated signaling pathway