The role of oxygen in the uptake of deuterium in lithiated graphite

We investigate the mechanism of deuterium retention by lithiated graphite and its relationship to the oxygen concentration through surface sensitive experiments and atomistic simulations. Deposition of lithium on graphite yielded 5%-8% oxygen surface concentration and when subsequently irradiated with D ions at energies between 500 and 1000 eV/amu and fluences over 10(16) cm(-2) the oxygen concentration rose to between 25% and 40%. These enhanced oxygen levels were reached in a few seconds compared to about 300 h when the lithiated graphite was allowed to adsorb oxygen from the ambient environment under equilibrium conditions. Irradiating graphite without lithium deposition, however, resulted in complete removal of oxygen to levels below the detection limit of XPS (e. g.

Metal Ion Implanted Compliant Electrodes in Dielectric Electroactive Polymer (EAP) Membranes

One of the key factors to obtain large displacements and high efficiency with dielectric electroactive polymer (DEAPs) actuators is to have compliant electrodes. Attempts to scale DEAPs down to the mm or micrometer range have encountered major difficulties, mostly due to the challenge of micropatterning sufficiently compliant electrodes. Simply evaporating or sputtering thin metallic films on elastomer membranes produces DEAPs whose stiffness is dominated by the metallic film. Low energy metal ion implantation for fabricating compliant electrodes in DEAPs presents several advantages: a) it is clean to work with, b) it does not add thick passive layers, and c) it can be easily patterned. We use this technology to fabricate DEAPs micro-actuators whose relative displacement is the same as for macro-scale DEAPs. With transmission electron microscope (TEM) we observed the formation of metallic clusters within the elastomer (PDMS) matrix, forming a nano-composite. We focus our studies on relating the properties of this nano-composite to the implantation parameters. We identified the optimal implantation parameters for which an implanted electrode presents an exceptional combination of high electrical conductivity and low compliance

Differentiating the role of lithium and oxygen in retaining deuterium on lithiated graphite plasma-facing components

Laboratory experiments have been used to investigate the fundamental interactions responsible for deuterium retention in lithiated graphite. Oxygen was found to be present and play a key role in experiments that simulated NSTX lithium conditioning, where the atomic surface concentration can increase to >40% when deuterium retention chemistry is observed. Quantum-classical molecular dynamic simulations elucidated this oxygen-deuterium effect and showed that oxygen retains significantly more deuterium than lithium in a simulated matrix with 20% lithium, 20% oxygen, and 60% carbon. Simulations further show that deuterium retention is even higher when lithium is removed from the matrix. Experiments artificially increased the oxygen content in graphite to approximately 16% and then bombarded with deuterium. XPS showed depletion of the oxygen and no enhanced deuterium retention, thus demonstrating that lithium is essential in retaining the oxygen that thereby retains deuterium

Snail regulates BMP and TGFβ pathways to control the differentiation status of glioma-initiating cells

Glioblastoma multiforme is a brain malignancy characterized by high heterogeneity, invasiveness, and resistance to current therapies, attributes related to the occurrence of glioma stem cells (GSCs). Transforming growth factor β (TGFβ) promotes self-renewal and bone morphogenetic protein (BMP) induces differentiation of GSCs. BMP7 induces the transcription factor Snail to promote astrocytic differentiation in GSCs and suppress tumor growth in vivo. We demonstrate that Snail represses stemness in GSCs. Snail interacts with SMAD signaling mediators, generates a positive feedback loop of BMP signaling and transcriptionally represses the TGFB1 gene, decreasing TGFβ1 signaling activity. Exogenous TGFβ1 counteracts Snail function in vitro, and in vivo promotes proliferation and re-expression of Nestin, confirming the importance of TGFB1 gene repression by Snail. In conclusion, novel insight highlights mechanisms whereby Snail differentially regulates the activity of the opposing BMP and TGFβ pathways, thus promoting an astrocytic fate switch and repressing stemness in GSCs

Microactuators based on ion-implanted dielectric Electroactive Polymer Membranes (EAP)

We report on the first ion-implanted dielectric electroactive polymer actuator that was successfully microfabricated and tested. Ion implantation is used to make the surface of the polymer locally conducting. Implanting the compliant electrodes solves the problem of how to microfabricate patterned electrodes having elasticity close to that of the insulating elastomer. Dieletric EAP actuators combine in an exceptional way high energy-density, while allowing large amplitude displacements [1,2]. The ion-implant approach avoids the deposition of metal electrodes on the polymer, normally accompanied with an undesired stiffening of the membrane. The actuator consists of a 35-um thick ion implanted PDMS membrane bonded to a silicon chip containing a hole. We observed 110-um vertical displacements of a square membrane measuring 1 mm2. ©2005 IEEE

The protein kinase LKB1 promotes self-renewal and blocks invasiveness in glioblastoma

The role of liver kinase B1 (LKB1) in glioblastoma (GBM) development remains poorly understood. LKB1 may regulate GBM cell metabolism and has been suggested to promote glioma invasiveness. After analyzing LKB1 expression in GBM patient mRNA databases and in tumor tissue via multiparametric immunohistochemistry, we observed that LKB1 was localized and enriched in GBM tumor cells that co-expressed SOX2 and NESTIN stemness markers. Thus, LKB1-specific immunohistochemistry can potentially reveal subpopulations of stem-like cells, advancing GBM patient molecular pathology. We further analyzed the functions of LKB1 in patient-derived GBM cultures under defined serum-free conditions. Silencing of endogenous LKB1 impaired 3D-gliomasphere frequency and promoted GBM cell invasion in vitro and in the zebrafish collagenous tail after extravasation of circulating GBM cells. Moreover, loss of LKB1 function revealed mitochondrial dysfunction resulting in decreased ATP levels. Treatment with the clinically used drug metformin impaired 3D-gliomasphere formation and enhanced cytotoxicity induced by temozolomide, the primary chemotherapeutic drug against GBM. The IC50 of temozolomide in the GBM cultures was significantly decreased in the presence of metformin. This combinatorial effect was further enhanced after LKB1 silencing, which at least partially, was due to increased apoptosis. The expression of genes involved in the maintenance of tumor stemness, such as growth factors and their receptors, including members of the platelet-derived growth factor (PDGF) family, was suppressed after LKB1 silencing. The defect in gliomasphere growth caused by LKB1 silencing was bypassed after supplementing the cells with exogenous PFDGF-BB. Our data support the parallel roles of LKB1 in maintaining mitochondrial homeostasis, 3D-gliomasphere survival, and hindering migration in GBM. Thus, the natural loss of, or pharmacological interference with LKB1 function, may be associated with benefits in patient survival but could result in tumor spread.Cancer Signaling networks and Molecular Therapeutic

DermO; an ontology for the description of dermatologic disease

Background: There have been repeated initiatives to produce standard nosologies and terminologies for cutaneous disease, some dedicated to the domain and some part of bigger terminologies such as ICD-10. Recently, formally structured terminologies, ontologies, have been widely developed in many areas of biomedical research. Primarily, these address the aim of providing comprehensive working erminologies for domains of knowledge, but because of the knowledge contained in the relationships between terms they can also be used computationally for many purposes. Results: We have developed an ontology of cutaneous disease, constructed manually by domain experts. With more than 3000 terms, DermO represents the most comprehensive formal dermatological disease terminology available. The disease entities are categorized in 20 upper level terms, which use a variety of features such as anatomical location, heritability, affected cell or tissue type, or etiology, as the features for classification, in line with professional practice and nosology in dermatology. Available in OBO flatfile and OWL 2 formats, it is integrated semantically with other ontologies and terminologies describing diseases and phenotypes. We demonstrate the application of DermO to text mining the biomedical literature and in the creation of a network describing the phenotypic relationships between cutaneous diseases. Conclusions: DermO is an ontology with broad coverage of the domain of dermatologic disease and we demonstrate here its utility for text mining and investigation of phenotypic relationships between dermatologic disorders. We envision that in the future it may be applied to the creation and mining of electronic health records, clinical training and basic research, as it supports automated inference and reasoning, and for the broader integration of skin disease information with that from other domain

Incidence, mortality, and burden of severe acute respiratory infection in Iran in 2015

Background: Severe Acute Respiratory Infection (SARI) is responsible for mortality and hospital admissions in millions of people across the world. The present study, for the first time, aimed at estimating the incidence, mortality, and burden of SARI in Iran in 2015. Methods: Disability Adjusted Life Years (DALYs) was used as an index to estimate the burden of SARI. The SARI-related DALYs was calculated using a method developed by the WHO for assessing the Global Burden of Diseases. DALYs are calculated as the sum of the Years Lost due to Disability (YLDs) and the Years of Life Lost (YLLs) due to premature mortality. The data on the incidence and mortality were obtained from the SARI surveillance system of Iran's Ministry of Health and Medical Education. The average duration until remission or death and the disease disability weight were set at four weeks and 0.373, respectively. Results: In 2015, the incidence of SARI was 21309 and 20885 among males and females, respectively. Moreover, 773 males and 737 females died from this disease (Case fatality rate was about 0.035). Total SARI-related DALYs in males and females was 17264 and 16720, respectively. Furthermore, YLLs was responsible for more than 96 of SARI-related DALYs in 2015. Conclusion: There was no significant difference between males and females in terms of the incidence, mortality, and burden of SARI in 2015. Epidemiological data are required to adopt appropriate policies and responses to prevent and control SARI. The incidence, mortality, fatality, and burden of SARI are significant in Iran. It is necessary to develop appropriate strategies, such as vaccination against major pathogens of the disease at least in high-risk groups, strengthening the disease surveillance system, and attracting the attention of policy makers and health authorities of the country. © 2019, Iranian Journal of Public Health. All rights reserved