The enhancement of the functional properties of materials at reduced dimensions is crucial for continuous advancements in nanoelectronic applications. Here, we report that the scale reduction leads ...to the emergence of an important functional property, ferroelectricity, challenging the long-standing notion that ferroelectricity is inevitably suppressed at the scale of a few nanometers. A combination of theoretical calculations, electrical measurements, and structural analyses provides evidence of room-temperature ferroelectricity in strain-free epitaxial nanometer-thick films of otherwise nonferroelectric strontium titanate (SrTiO3). We show that electrically induced alignment of naturally existing polar nanoregions is responsible for the appearance of a stable net ferroelectric polarization in these films. This finding can be useful for the development of low-dimensional material systems with enhanced functional properties relevant to emerging nanoelectronic devices.
High-β_{θe} (a ratio of the electron thermal pressure to the poloidal magnetic pressure) steady-state long-pulse plasmas with steep central electron temperature gradient are achieved in the ...Experimental Advanced Superconducting Tokamak. An intrinsic current is observed to be modulated by turbulence driven by the electron temperature gradient. This turbulent current is generated in the countercurrent direction and can reach a maximum ratio of 25% of the bootstrap current. Gyrokinetic simulations and experimental observations indicate that the turbulence is the electron temperature gradient mode (ETG). The dominant mechanism for the turbulent current generation is due to the divergence of ETG-driven residual flux of current. Good agreement has been found between experiments and theory for the critical value of the electron temperature gradient triggering ETG and for the level of the turbulent current. The maximum values of turbulent current and electron temperature gradient lead to the destabilization of an m/n=1/1 kink mode, which by counteraction reduces the turbulence level (m and n are the poloidal and toroidal mode number, respectively). These observations suggest that the self-regulation system including turbulence, turbulent current, and kink mode is a contributing mechanism for sustaining the steady-state long-pulse high-β_{θe} regime.
Ubiquitously distributed in different plant species, plant lectins are highly diverse carbohydrate‐binding proteins of non‐immune origin. They have interesting pharmacological activities and ...currently are of great interest to thousands of people working on biomedical research in cancer‐related problems. It has been widely accepted that plant lectins affect both apoptosis and autophagy by modulating representative signalling pathways involved in Bcl‐2 family, caspase family, p53, PI3K/Akt, ERK, BNIP3, Ras‐Raf and ATG families, in cancer. Plant lectins may have a role as potential new anti‐tumour agents in cancer drug discovery. Thus, here we summarize these findings on pathway‐ involved plant lectins, to provide a comprehensive perspective for further elucidating their potential role as novel anti‐cancer drugs, with respect to both apoptosis and autophagy in cancer pathogenesis, and future therapy.
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A multiscale model is developed to investigate the evolution mechanisms of site-specific grain structures during additive manufacturing (AM) of metallic alloys, using the selective ...electron beam melting (SEBM) fabrication of Ti-6Al-4V as an example. Specifically, finite-element method is utilized to predict the thermal response at macroscale during SEBM, and the extracted thermal information is then input into a temperature-dependent phase-field model to simulate the grain growth at mesoscale. The grain epitaxial growth, grain selection, grain nucleation and layer-by-layer manufacturing fashion are incorporated, in order to accurately predict grain structure development and relevant physical processes during AM. It is found that, the development of the predominant grain structures in the thick and thin walls, i.e., the large vertical columnar β//Nz grains and slanted columnar grains with various grain orientations, respectively, can be attributed to the competition and collaboration between the thermal gradient and the crystallographically preferred grain growth, as shown from the different growth stages in the simulations. Good agreements in the final grain structures and textures are achieved between the experimental observations and numerical simulations. The present study potentially offers valuable insights and guidance toward designing AM conditions to tailor the grain structures and textures.
A fast Fourier transform (FFT) based computational approach integrating phase-field method (PFM) and crystal plasticity (CP) is proposed to model recrystallization of plastically deformed ...polycrystals in three dimensions (3-D). CP at the grain level is employed as the constitutive description to predict the inhomogeneous distribution of strain and stress fields after plastic deformation of a polycrystalline aggregate while the kinetics of recrystallization is obtained employing a PFM in the plastically deformed grain structure. The elasto-viscoplastic equilibrium is guaranteed during each step of temporal phase-field evolution. Static recrystallization involving plasticity during grain growth is employed as an example to demonstrate the proposed computational framework. The simulated recrystallization kinetics is compared using the classical Johnson–Mehl–Avrami–Kolmogorov (JMAK) theory. This study also gives us a new computational pathway to explore the plasticity-driven evolution of 3D microstructures.
The unique immunomodulatory properties of mesenchymal stem cells (MSCs) make them an invaluable cell type for the repair of tissue/ organ damage caused by chronic inflammation or autoimmune ...disorders. Although they hold great promise in the treatment of immune disorders such as graft versus host disease (GvHD) and allergic disorders, there remain many challenges to overcome before their widespread clinical application. An understanding of the biological properties of MSCs will clarify the mechanisms of MSC-based transplantation for immunomodulation. In this review, we summarize the preclinical and clinical studies of MSCs from different adult tissues, discuss the current hurdles to their use and propose the future development of pluripotent stem cell-derived MSCs as an approach to immunomodulation therapy.
Summary
Epidemiologic evidence has shown inconsistent findings regarding the relationships between abdominal fatness, as measured by waist circumferences (WC) or waist‐to‐hip ratio (WHR), and risks ...of pre‐ and postmenopausal breast cancer (BC). A dose–response meta‐analysis of prospective studies was conducted to address these issues. Potentially eligible studies were identified by searching PubMed and EMBASE databases, and by carefully reviewing the bibliographies of retrieved publications and related reviews. The summary relative risks (RRs) with 95% confidence intervals (CIs) were calculated using a random‐effects model. When the most fully adjusted RRs were combined, both WC (14 studies, RR per 10‐cm increase = 1.06, 95% CI: 1.04–1.09, I2 = 29.9%) and WHR (15 studies, RR per 0.1‐unit increase = 1.07, 95% CI: 1.01–1.14, I2 = 52.9%) were significantly positively associated with postmenopausal BC, but neither WC (eight studies, RR per 10‐cm increase = 1.05, 95% CI: 0.99–1.10, I2 = 0%) nor WHR (11 studies, RR per 0.1‐unit increase = 1.07, 95% CI: 0.95–1.21, I2 = 59.7%) were associated with premenopausal BC. The WHR‐postmenopausal BC association lost statistical significance after correcting publication bias (RR per 0.1‐unit increase = 1.06, 95% CI: 0.99–1.13). When considering BMI‐adjusted RRs, WC was associated with both pre‐ (five studies, RR per 10‐cm increase = 1.09, 95% CI: 1.02–1.16, I2 = 0%) and postmenopausal BC (seven studies, RR per 10‐cm increase = 1.05, 95% CI: 1.02–1.08, I2 = 6.3%), whereas WHR was not associated with either pre‐ (seven studies, RR per 0.1‐unit increase = 1.12, 95% CI: 0.94–1.34, I2 = 70.9%) or postmenopausal BC (eight studies, RR per 0.1‐unit increase = 1.05, 95% CI: 0.98–1.13, I2 = 57.3%). Among non‐current (former or never) users of hormone replacement therapy, the summary RR per 10‐cm increase of postmenopausal BC associated with WC was 1.08 (95% CI: 1.03–1.05, I2 = 69.2%, seven studies; BMI‐adjusted RR = 1.05, 95% CI: 1.02–1.09, I2 = 22.8%, four studies). This meta‐analysis indicates that central obesity measured by WC, but not by WHR, is associated with modestly increased risks of both pre‐ and postmenopausal BC independent of general obesity.
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