1,357 research outputs found

    Hole polaron formation and migration in olivine phosphate materials

    Full text link
    By combining first principles calculations and experimental XPS measurements, we investigate the electronic structure of potential Li-ion battery cathode materials LiMPO4 (M=Mn,Fe,Co,Ni) to uncover the underlying mechanisms that determine small hole polaron formation and migration. We show that small hole polaron formation depends on features in the electronic structure near the valence-band maximum and that, calculationally, these features depend on the methodology chosen for dealing with the correlated nature of the transition-metal d-derived states in these systems. Comparison with experiment reveals that a hybrid functional approach is superior to GGA+U in correctly reproducing the XPS spectra. Using this approach we find that LiNiPO4 cannot support small hole polarons, but that the other three compounds can. The migration barrier is determined mainly by the strong or weak bonding nature of the states at the top of the valence band, resulting in a substantially higher barrier for LiMnPO4 than for LiCoPO4 or LiFePO4

    The role of EGFR double minutes in modulating the response of malignant gliomas to radiotherapy.

    Get PDF
    EGFR amplification in cells having double minute chromosomes (DM) is commonly found in glioblastoma multiforme (GBM); however, how much it contributes to the current failure to treat GBM successfully is unknown. We studied two syngeneic primary cultures derived from a GBM with and without cells carrying DM, for their differential molecular and metabolic profiles, in vivo growth patterns, and responses to irradiation (IR). Each cell line has a distinct molecular profile consistent with an invasive "go" (with DM) or angiogenic "grow" phenotype (without DM) demonstrated in vitro and in intracranial xenograft models. Cells with DM were relatively radio-resistant and used higher glycolytic respiration and lower oxidative phosphorylation in comparison to cells without them. The DM-containing cell was able to restore tumor heterogeneity by mis-segregation of the DM-chromosomes, giving rise to cell subpopulations without them. As a response to IR, DM-containing cells switched their respiration from glycolic metabolism to oxidative phosphorylation and shifted molecular profiles towards that of cells without DM. Irradiated cells with DM showed the capacity to alter their extracellular microenvironment to not only promote invasiveness of the surrounding cells, regardless of DM status, but also to create a pro-angiogenic tumor microenvironment. IR of cells without DM was found primarily to increase extracellular MMP2 activity. Overall, our data suggest that the DM-containing cells of GBM are responsible for tumor recurrence due to their high invasiveness and radio-resistance and the mis-segregation of their DM chromosomes, to give rise to fast-growing cells lacking DM chromosomes

    Nature-derived epigallocatechin gallate/duck’s feet collagen/hydroxyapatite composite sponges for enhanced bone tissue regeneration

    Get PDF
    Scaffolds mimicking structural and chemical characteristics of the native bone tissues are critical for bone tissue engineering. Herein, we have developed and characterized epigallocatechin gallate/duck's feet collagen/hydroxyapatite (EGCG/DC/HAp) composite sponges that enhanced the bone tissue regeneration. The three-dimensional composite sponges were synthesized by loading various amounts (i.e. 1, 5 and 10 μM) of EGCG to duck feet derived collagen followed by freeze-drying and then coating with hydroxyapatite. Several measuremental techniques were employed to examine the properties of the as-fabricated composite sponges including morphology and structure, porosity, compressive strength, etc. and as well compared with pristine duck feet derived collagen. SEM observations of EGCG/DC/HAp sponges showed the formation of a highly porous collagen matrix with EGCG embodiment. The porosity and pore size of sponges were found to increase by high EGCG content. The compressive strength was calculated as 3.54 ± 0.04, 3.63 ± 0.03, 3.89 ± 0.05, 4.047 ± 0.05 MPa for 1, 5 and 10 μM EGCG/DC/HAp sponges, respectively. Osteoblast-like cell (BMSCs isolated from rabbit) culture and in vivo experiments with EGCG/DC/HAp sponges implanted in nude mouse followed by histological staining showed enhanced cell internalization and attachment, cell proliferation, alkaline phosphatase expressions, indicating that EGCG/DC/HAp sponges have ahigh biocompatibility. Moreover, highEGCG content in the EGCG/DC/HAp sponges have led to increased cellular behavior. Collectively, the 5 μM of EGCG/DC/HAp sponges were suggested as the potential candidates for bone tissue regeneration.This research was supported by Technology Commercialization Support Program [grant number 814005-03-3-HD020], MIFAFF; and Basic Science Research Program [grant number NRF2017R1A2B3010270] through the National Research Foundation of Korea, Ministry of Science, ICT and Future Planning, Republic of Korea.info:eu-repo/semantics/publishedVersio

    Evaluation of different formulations of gellan gum-based hydrogels for tissue engineering of intervertebral disc

    Get PDF
    Gellan gum based-hydrogels present advantageous features for application as acellular and cellular nucleus pulposus (NP) substitutes due to the possibility of fine-tuning its physico-chemical and biological properties. In this study, ionic-crosslinked hydrogel discs were produced by means of mixing a raw and chemically modified material, i.e., high acyl gellan gum (HAGG) and methacrylated low acyl gellan gum (GG-MA), respectively. The hydrogel discs were characterized in terms of its mechanical properties and degradation/swelling ability. The biocompatibility of the different hydrogel formulations was assessed in vitro using NP rabbit cells isolated from the intervertebral disc. The biological performance of the developed gellan gum-based hydrogels formulations was evaluated by: (i) culturing of NP cells in the presence of the hydrogel leachables, and (ii) seeding or encapsulation of the NP cells within the hydrogels. The present work demonstrated that as HAGG content increases, the modulus of the hydrogels decreases. Moreover, the increase of the HAGG content induces a higher weight loss of the GG-MA/HA-GG formulation as compared to GG-MA hydrogel. The in vitro study revealed that hydrogels are non-cytotoxic and support the encapsulation of rabbit NP cells. The methacrylated gellan gum and formulations possessing high acyl gellan gum present tunable properties that may be interesting for application as NP substitutes

    Micro-fabrication of Carbon Structures by Pattern Miniaturization in Resorcinol-Formaldehyde Gel

    Full text link
    A simple and novel method to fabricate and miniaturize surface and sub-surface micro-structures and micro-patterns in glassy carbon is proposed and demonstrated. An aqueous resorcinol-formaldehyde (RF) sol is employed for micro-molding of the master-pattern to be replicated, followed by controlled drying and pyrolysis of the gel to reproduce an isotropically shrunk replica in carbon. The miniaturized version of the master-pattern thus replicated in carbon is about one order of magnitude smaller than original master by repeating three times the above cycle of molding and drying. The micro-fabrication method proposed will greatly enhance the toolbox for a facile fabrication of a variety of Carbon-MEMS and C-microfluidic devices.Comment: 16 pages, 5 figure

    Delivery of cytoplasmic and apoplastic effectors from <i>Phytophthora infestans </i>haustoria by distinct secretion pathways

    Get PDF
    • The potato blight pathogen Phytophthora infestans secretes effector proteins that are delivered inside (cytoplasmic) or can act outside (apoplastic) plant cells to neutralise host immunity. Little is known about how and where effectors are secreted during infection, yet such knowledge is essential to understand and combat crop disease.• We used transient Agrobacterium-mediated in planta expression, transformation of P. infestans with fluorescent protein-fusions and confocal microscopy to investigate delivery of effectors to plant cells during infection.• The cytoplasmic effector Pi04314, expressed as an mRFP-fusion protein with a signal peptide to secrete it from plant cells, does not passively re-enter the cells upon secretion. However, Pi04314-mRFP expressed in P. infestans is translocated from haustoria, which form intimate interactions with plant cells, to accumulate at its sites-of-action in the host nucleus. The well-characterised apoplastic effector EPIC1 was also secreted from haustoria. EPIC1 secretion was inhibited by brefeldin A (BFA), demonstrating that it is delivered by conventional Golgi-mediated secretion. In contrast, Pi04314 secretion was insensitive to BFA treatment, indicating that the cytoplasmic effector follows an alternative route for delivery into plant cells.• P. infestans haustoria are thus sites for delivery of both apoplastic and cytoplasmic effectors during infection, following distinct secretion pathways

    The Role of Health Behaviours Across the Life Course in the Socioeconomic Patterning of All-Cause Mortality: The West of Scotland Twenty-07 Prospective Cohort Study

    Get PDF
    Background: Socioeconomic differentials in mortality are increasing in many industrialised countries. Purpose: This study aims to examine the role of behaviours (smoking, alcohol, exercise, and diet) in explaining socioeconomic differentials in mortality and whether this varies over the life course, between cohorts and by gender. Methods: Analysis of two representative population cohorts of men and women, born in the 1950s and 1930s, were performed. Health behaviours were assessed on five occasions over 20 years. Results: Health behaviours explained a substantial part of the socioeconomic differentials in mortality. Cumulative behaviours and those that were more strongly associated with socioeconomic status had the greatest impact. For example, in the 1950s cohort, the age-sex adjusted hazard ratio comparing respondents with manual versus non-manual occupational status was 1.80 (1.25, 2.58); adjustment for cumulative smoking over 20 years attenuated the association by 49 %, diet by 43 %, drinking by 13 % and inactivity by only 1%. Conclusions: Health behaviours have an important role in explaining socioeconomic differentials in mortality. © 2013 The Author(s)

    Global, regional, and national burden of chronic kidney disease, 1990–2017 : a systematic analysis for the Global Burden of Disease Study 2017

    Get PDF
    Background Health system planning requires careful assessment of chronic kidney disease (CKD) epidemiology, but data for morbidity and mortality of this disease are scarce or non-existent in many countries. We estimated the global, regional, and national burden of CKD, as well as the burden of cardiovascular disease and gout attributable to impaired kidney function, for the Global Burden of Diseases, Injuries, and Risk Factors Study 2017. We use the term CKD to refer to the morbidity and mortality that can be directly attributed to all stages of CKD, and we use the term impaired kidney function to refer to the additional risk of CKD from cardiovascular disease and gout. Methods The main data sources we used were published literature, vital registration systems, end-stage kidney disease registries, and household surveys. Estimates of CKD burden were produced using a Cause of Death Ensemble model and a Bayesian meta-regression analytical tool, and included incidence, prevalence, years lived with disability, mortality, years of life lost, and disability-adjusted life-years (DALYs). A comparative risk assessment approach was used to estimate the proportion of cardiovascular diseases and gout burden attributable to impaired kidney function. Findings Globally, in 2017, 1·2 million (95% uncertainty interval [UI] 1·2 to 1·3) people died from CKD. The global all-age mortality rate from CKD increased 41·5% (95% UI 35·2 to 46·5) between 1990 and 2017, although there was no significant change in the age-standardised mortality rate (2·8%, −1·5 to 6·3). In 2017, 697·5 million (95% UI 649·2 to 752·0) cases of all-stage CKD were recorded, for a global prevalence of 9·1% (8·5 to 9·8). The global all-age prevalence of CKD increased 29·3% (95% UI 26·4 to 32·6) since 1990, whereas the age-standardised prevalence remained stable (1·2%, −1·1 to 3·5). CKD resulted in 35·8 million (95% UI 33·7 to 38·0) DALYs in 2017, with diabetic nephropathy accounting for almost a third of DALYs. Most of the burden of CKD was concentrated in the three lowest quintiles of Socio-demographic Index (SDI). In several regions, particularly Oceania, sub-Saharan Africa, and Latin America, the burden of CKD was much higher than expected for the level of development, whereas the disease burden in western, eastern, and central sub-Saharan Africa, east Asia, south Asia, central and eastern Europe, Australasia, and western Europe was lower than expected. 1·4 million (95% UI 1·2 to 1·6) cardiovascular disease-related deaths and 25·3 million (22·2 to 28·9) cardiovascular disease DALYs were attributable to impaired kidney function. Interpretation Kidney disease has a major effect on global health, both as a direct cause of global morbidity and mortality and as an important risk factor for cardiovascular disease. CKD is largely preventable and treatable and deserves greater attention in global health policy decision making, particularly in locations with low and middle SDI
    corecore