2,159 research outputs found
Thermo-electrochemical production of compressed hydrogen from methane with near-zero energy loss
[EN] Conventional production of hydrogen requires large industrial plants to minimize energy losses and capital costs associated with steam reforming, water-gas shift, product separation and compression. Here we present a protonic membrane reformer (PMR) that produces high-purity hydrogen from steam methane reforming in a single-stage process with near-zero energy loss. We use a BaZrO3-based proton-conducting electrolyte deposited as a dense film on a porous Ni composite electrode with dual function as a reforming catalyst. At 800 degrees C, we achieve full methane conversion by removing 99% of the formed hydrogen, which is simultaneously compressed electrochemically up to 50 bar. A thermally balanced operation regime is achieved by coupling several thermo-chemical processes. Modelling of a small-scale (10 kg H-2 day-1) hydrogen plant reveals an overall energy efficiency of >87%. The results suggest that future declining electricity prices could make PMRs a competitive alternative for industrial-scale hydrogen plants integrating CO2 capture.This work was supported by the Research Council of Norway (grant 256264) and the Spanish Government (SEV-2016-0683 grant).Malerød-Fjeld, H.; Clark, D.; Yuste Tirados, I.; Zanón González, R.; Catalán-Martínez, D.; Beeaff, D.; Hernández Morejudo, S.... (2017). Thermo-electrochemical production of compressed hydrogen from methane with near-zero energy loss. Nature Energy. 2(12):923-931. https://doi.org/10.1038/s41560-017-0029-4S923931212Morejudo, S. H. et al. Direct conversion of methane to aromatics in a catalytic co-ionic membrane reactor. Science 353, 563–566 (2016).Chu, S. & Majumdar, A. Opportunities and challenges for a sustainable energy future. Nature 488, 294–303 (2012).Logan, B. E. & Elimelech, M. Membrane-based processes for sustainable power generation using water. Nature 488, 313–319 (2012).Rostrup-Nielsen, J. R. Catalysis and large-scale conversion of natural gas. Catal. Today 21, 257–267 (1994).Voss, C. Applications of pressure swing adsorption technology. Adsorption 11, 527–529 (2005).Gallucci, F., Fernandez, E., Corengia, P. & van Sint Annaland, M. Recent advances on membranes and membrane reactors for hydrogen production. Chem. Eng. Sci. 92, 40–66 (2013).Boeltken, T., Wunsch, A., Gietzelt, T., Pfeifer, P. & Dittmeyer, R. Ultra-compact microstructured methane steam reformer with integrated Palladium membrane for on-site production of pure hydrogen: Experimental demonstration. Int. J. Hydrogen Energy 39, 18058–18068 (2014).Al-Mufachi, N. A., Rees, N. V. & Steinberger-Wilkens, R. Hydrogen selective membranes: A review of palladium-based dense metal membranes. Renew. Sustainable Energy Rev. 47, 540–551 (2015).Sengodan, S. et al. Layered oxygen-deficient double perovskite as an efficient and stable anode for direct hydrocarbon solid oxide fuel cells. Nat. Mater. 14, 205–209 (2015).Myung, J.-h, Neagu, D., Miller, D. N. & Irvine, J. T. S. Switching on electrocatalytic activity in solid oxide cells. Nature 537, 528–531 (2016).Iwahara, H., Uchida, H., Ono, K. & Ogaki, K. Proton conduction in sintered oxides based on BaCeO3. J. Electrochem. Soc. 135, 529–533 (1988).Hamakawa, S., Hibino, T. & Iwahara, H. Electrochemical methane coupling using proton conductors. J. Electrochem. Soc. 140, 459–462 (1993).Bonanos, N., Knight, K. S. & Ellis, B. Perovskite solid electrolytes: structure, transport properties and fuel cell applications. Solid State Ion. 79, 161–170 (1995).Norby, T. Solid-state protonic conductors: principles, properties, progress and prospects. Solid State Ion. 125, 1–11 (1999).Kreuer, K. D. On the development of proton conducting materials for technological applications. Solid State Ion. 97, 1–15 (1997).Kreuer, K. D. Aspects of the formation and mobility of protonic charge carriers and the stability of perovskite-type oxides. Solid State Ion. 125, 285–302 (1999).Kreuer, K. D. Proton-conducting oxides. Annu. Rev. Mater. Res. 33, 333–359 (2003).Tao, S. W. & Irvine, J. T. S. A stable, easily sintered proton-conducting oxide electrolyte for moderate-temperature fuel cells and electrolyzers. Adv. Mater. 18, 11581-1584 (2006).Wang, H., Peng, R., Wu, X., Hu, J. & Xia, C. Sintering behavior and conductivity study of yttrium-doped BaCeO3–BaZrO3 solid solutions using ZnO additives. J. Am. Ceram. Soc. 92, 2623–2629 (2009).Coors, W. G. in Advances in Ceramics—Synthesis and Characterization, Processing and Specific Applications (Ed. Sikalidis, C.) Ch. 22, 501–520 (InTech, UK, 2011) (2011).Manabe, R. et al. Surface protonics promotes catalysis. Sci. Rep. 6, 38007, (2016).Rohland, B., Eberle, K., Ströbel, R., Scholta, J. & Garche, J. Electrochemical hydrogen compressor. Electrochimica Acta 43, 3841–3846 (1998).Kochetova, N., Animitsa, I., Medvedev, D., Demin, A. & Tsiakaras, P. Recent activity in the development of proton-conducting oxides for high-temperature applications. RSC Adv. 6, 73222–73268 (2016).Yamazaki, Y. et al. Proton trapping in yttrium-doped barium zirconate. Nat. Mater. 12, 647–651 (2013).Kjølseth, C. et al. Space-charge theory applied to the grain boundary impedance of proton conducting BaZr0.9Y0.1O3-δ . Solid State Ion. 181, 268–275 (2010).Coors, W. G A stoichiometric titration method for measuring galvanic hydrogen flux in ceramic hydrogen separation membranes. J. Membr. Sci. 458, 245–253 (2014).Zeppieri, M., Villa, P. L., Verdone, N., Scarsella, M. & De Filippis, P. Kinetic of methane steam reforming reaction over nickel- and rhodium-based catalysts. Appl. Catal. A 387, 147–154 (2010).Wang, B., Zhu, J. & Lin, Z. A theoretical framework for multiphysics modeling of methane fueled solid oxide fuel cell and analysis of low steam methane reforming kinetics. Appl. Energy 176, 1–11 (2016).Overview of Electricity Production and Use in Europe (European Environment Agency, 2016).Edwards, R., Larive, J.-F., Rickeard, D. & Weindorf, W. Well-To-Wheels Analysis of Future Automotive Fuels and Powertrains in the European Context, Well-to-Tank Report Version 4.a, JEC Well-to-Wheels Analysis (Joint Research Centre, 2014).Cho, V. H., Hamilton, B. A. & Kuehn, N. J. Assessment of Hydrogen Production with CO 2 Capture Volume 1: Baseline State-of-the-Art Plants (National Energy Technology Laboratory, 2010).Schjølberg, I. et al. Small-Scale Reformers for On-Site Hydrogen Supply (International Energy Agency-Hydrogen Implementing Agreement, 2012).de Visser, E. et al. Dynamis CO2 quality recommendations. Int. J. Greenhouse Gas Control 2, 478–484 (2008).Bertucciolo, L. et al. Development of Water Electrolysis in the European Union (Fuel Cells and Hydrogen Joint Undertaking, 2014).Edwards, R. et al. Well-To-Wheels Analysis of Future Automotive Fuels and Powertrains in the European Context, Well-to-Wheels Report Version 4.a, JEC Well-to-Wheels Analysis (Joint Research Centre 2014).Huss, A., Maas, H. & Hass, H. Well-to-Wheels Analysis of Future Automotive Fuels and Powertrains in the European Context, Tank-to-Wheels Report Version 4.0, JEC Technical Reports (Joint Research Centre, 2013)
The Economic Benefits Resulting from the First 8 Years of the Global Programme to Eliminate Lymphatic Filariasis (2000–2007)
Lymphatic filariasis (LF), commonly known as ‘elephantiasis’, is one of the world's most debilitating infectious diseases. In 83 countries worldwide, more than 1.3 billion people are at risk of infection with an estimated 120 million individuals already infected. A recent publication reviewing the health impact of the first 8 years of the Global Programme to Eliminate Lymphatic Filariasis (GPELF) demonstrated the enormous health benefits achieved in populations receiving annual mass drug administration (MDA), as a result of infection prevented, disease progression halted, and ancillary treatment of co-infections. To date, however, no studies have estimated the economic value of these health benefits, either to the individuals or the societies afflicted with LF. Our study estimates that US2.2 billion will be saved by the health systems of endemic countries. Treating endemic populations is possible at very low cost – particularly because of the generous drug donations from two pharmaceutical companies – but results in enormous economic benefits. Findings from this study yield a much clearer understanding the GPELF's full economic impact and strengthen the conviction that it is a ‘best buy’ in global health
Particulate air pollution and chronic ischemic heart disease in the eastern United States: a county level ecological study using satellite aerosol data
<p>Abstract</p> <p>Background</p> <p>There are several known factors that cause ischemic heart disease. However, the part played by air pollution still remains something of a mystery. Recent attention has focused on the chronic effect of particulate matter on heart disease. Satellite-derived aerosol optical depth (AOD) was found to be correlated with <it>PM</it><sub>2.5 </sub>in the eastern US. The objective of this study was to examine if there is an association between aerosol air pollution as indicated by AOD and chronic ischemic heart disease (CIHD) in the eastern US.</p> <p>Methods</p> <p>An ecological geographic study method was employed. Race and age standardized mortality rate (SMR) of CIHD was computed for each of the 2306 counties for the time period 2003–2004. A mean AOD raster grid for the same period was derived from Moderate Resolution Imaging Spectrometer (MODIS) aerosol data and the average AOD was calculated for each county. A bivariate Moran's I scatter plot, a map of local indicator of spatial association (LISA) clusters, and three regression models (ordinary least square, spatial lag, and spatial error) were used to analyze the relationship between AOD and CIHD SMR.</p> <p>Results</p> <p>The global Moran's I value is 0.2673 (<it>p </it>= 0.001), indicating an overall positive spatial correlation of CIHD SMR and AOD. The entire study area is dominated by spatial clusters of AOD against SMR (high AOD and high SMR in the east, and low AOD and low SMR in the west) (permutations = 999, <it>p </it>= 0.05). Of the three regression models, the spatial error model achieved the best fit (R<sup>2 </sup>= 0.28). The effect of AOD is positive and significant (beta = 0.7774, p = 0.01).</p> <p>Conclusion</p> <p>Aerosol particle pollution has adverse effect on CIHD mortality risk in the eastern US. High risk of CIHD mortality was found in areas with elevated levels of outdoor aerosol air pollution as indicated by satellite derived AOD. The evidence of the association would support targeting of policy interventions on such areas to reduce air pollution levels. Remote sensing AOD data could be used as an alternative health-related indictor of air quality.</p
Human germ cell tumours: expression of γ-glutamyl transpeptidase and sensitivity to cisplatin
Previous studies have shown that the enzyme γ-glutamyl transpeptidase (GGT) is essential for the nephrotoxicity of cisplatin. This study was designed to determine whether GGT activity is necessary for the therapeutic effect of the drug. The relationship between GGT expression and clinical response to platinum-based chemotherapy was examined in 41 human germ cell tumours. Sections of formalin-fixed, paraffin-embedded tumours were immunohistochemically stained with an antibody directed against human GGT. There was no expression of GGT in any of the 17 seminomas or four dysgerminomas; whereas, 12/12 ovarian yolk sac tumours and 4/4 embryonal carcinomas of the testis were GGT-positive. In stage I tumours fewer tumour cells expressed GGT than in later stage tumours. In four germ cell tumours of mixed histology, the seminomatous and dysgerminoma areas were GGT-negative while the areas of the tumour with yolk sac or embryonal histology contained GGT-positive tumour cells. The patients with seminomas or dysgerminomas who were treated with cisplatin-based chemotherapy, all had a complete response despite the absence of GGT expression in these tumours. Fifteen of the 16 patients with yolk sac or embryonal carcinomas received cisplatin-based chemotherapy following surgery. Twelve had a complete response, while three failed to respond to platinum-based therapy. There was no correlation between the level of GGT-expression and response to therapy in this group. Three of the four patients with tumours of mixed histology were treated with cisplatin-based therapy, and had a complete response. Therefore, expression of GGT is not necessary for the therapeutic effect of cisplatin in germ cell tumours. The results from this study suggest that systemic inhibition of GGT would inhibit the nephrotoxic side-effect of cisplatin without interfering with its activity towards germ cell tumours. © 1999 Cancer Research Campaig
The Snail repressor recruits EZH2 to specific genomic sites through the enrollment of the lncRNA HOTAIR in epithelial-to-mesenchymal transition
The transcription factor Snail is a master regulator of cellular identity and epithelial-to-mesenchymal transition (EMT) directly repressing a broad repertoire of epithelial genes. How chromatin modifiers instrumental to its activity are recruited to Snail-specific binding sites is unclear. Here we report that the long non-coding RNA (lncRNA) HOTAIR (for HOX Transcript Antisense Intergenic RNA) mediates a physical interaction between Snail and enhancer of zeste homolog 2 (EZH2), an enzymatic subunit of the polycomb-repressive complex 2 and the main writer of chromatin-repressive marks. The Snail-repressive activity, here monitored on genes with a pivotal function in epithelial and hepatic morphogenesis, differentiation and cell-type identity, depends on the formation of a tripartite Snail/HOTAIR/EZH2 complex. These results demonstrate an lncRNA-mediated mechanism by which a transcriptional factor conveys a general chromatin modifier to specific genes, thereby allowing the execution of hepatocyte transdifferentiation; moreover, they highlight HOTAIR as a crucial player in the Snail-mediated EMT.Oncogene advance online publication, 25 July 2016; doi:10.1038/onc.2016.260
Galactic and Extragalactic Samples of Supernova Remnants: How They Are Identified and What They Tell Us
Supernova remnants (SNRs) arise from the interaction between the ejecta of a
supernova (SN) explosion and the surrounding circumstellar and interstellar
medium. Some SNRs, mostly nearby SNRs, can be studied in great detail. However,
to understand SNRs as a whole, large samples of SNRs must be assembled and
studied. Here, we describe the radio, optical, and X-ray techniques which have
been used to identify and characterize almost 300 Galactic SNRs and more than
1200 extragalactic SNRs. We then discuss which types of SNRs are being found
and which are not. We examine the degree to which the luminosity functions,
surface-brightness distributions and multi-wavelength comparisons of the
samples can be interpreted to determine the class properties of SNRs and
describe efforts to establish the type of SN explosion associated with a SNR.
We conclude that in order to better understand the class properties of SNRs, it
is more important to study (and obtain additional data on) the SNRs in galaxies
with extant samples at multiple wavelength bands than it is to obtain samples
of SNRs in other galaxiesComment: Final 2016 draft of a chapter in "Handbook of Supernovae" edited by
Athem W. Alsabti and Paul Murdin. Final version available at
https://doi.org/10.1007/978-3-319-20794-0_90-
Factors Affecting Population Dynamics of Maternally Transmitted Endosymbionts in Bemisia tabaci
While every individual of Bemisia tabaci (Hemiptera: Aleyrodidae) harbors the primary symbiont (P-symbiont) Portiera, the infection frequencies of the six secondary symbionts (S-symbionts) including Hamiltonella, Arsenophonus, Cardinium, Wolbachia, Rickettsia and Fritschea vary greatly among different populations. To characterize the factors influencing the infection dynamics of the six S-symbionts in B. tabaci, gene-specific PCR were conducted to screen for the presence of the P-symbiont Portiera and the six S-symbionts in 61 (17 B and 44 Q biotypes) field populations collected from different plant species and locations in China. All individuals of the 61 populations hosted the P-symbiont Portiera, but none of them harbored Arsenophonus and Fritschea. The presence and infection rates of Hamiltonella, Cardinium, Rickettsia, Wolbachia and their co-infections Rickettsia + Hamiltonella (RH), Rickettsia + Cardinium (RC), Hamiltonella + Cardinium (HC) and Rickettsia + Hamiltonella + Cardinium (RHC) varied significantly among the 61 field populations; and the observed variations can be explained by biotypes, sexes, host plants and geographical locations of these field populations. Taken together, at least three factors including biotype, host plant and geographical location affect the infection dynamics of S-symbionts in B. tabaci
m^6A RNA methylation promotes XIST-mediated transcriptional repression
The long non-coding RNA X-inactive specific transcript (XIST) mediates the transcriptional silencing of genes on the X chromosome. Here we show that, in human cells, XIST is highly methylated with at least 78 N^6-methyladenosine (m^6A) residues—a reversible base modification of unknown function in long non-coding RNAs. We show that m^6A formation in XIST, as well as in cellular mRNAs, is mediated by RNA-binding motif protein 15 (RBM15) and its paralogue RBM15B, which bind the m^6A-methylation complex and recruit it to specific sites in RNA. This results in the methylation of adenosine nucleotides in adjacent m^6A consensus motifs. Furthermore, we show that knockdown of RBM15 and RBM15B, or knockdown of methyltransferase like 3 (METTL3), an m^6A methyltransferase, impairs XIST-mediated gene silencing. A systematic comparison of m^6A-binding proteins shows that YTH domain containing 1 (YTHDC1) preferentially recognizes m^6A residues on XIST and is required for XIST function. Additionally, artificial tethering of YTHDC1 to XIST rescues XIST-mediated silencing upon loss of m^6A. These data reveal a pathway of m^6A formation and recognition required for XIST-mediated transcriptional repression
Analysis of isoflavones and flavonoids in human urine by UHPLC
A rapid, ultra high-performance liquid chromatographic (UHPLC) method has been developed and validated for simultaneous identification and analysis of the isoflavones genistein, daidzein, glycitin, puerarin, and biochanin A, and the flavonoids (±)-catechin, (−)-epicatechin, rutin, hesperidin, neohesperidin, quercitrin, and hesperetin in human urine. Urine samples were incubated with β-glucuronidase/sulfatase. UHPLC was performed with a Hypersil Gold (50 × 2.1 mm, 1.9 μm) analytical column. Elution was with a gradient prepared from aqueous trifluoroacetic acid (0.05%) and acetonitrile. UV detection was performed at 254 and 280 nm. The calibration curves were indicative of good linearity (r2 ≥ 0.9992) in the range of interest for each analyte. LODs ranged between 15.4 and 107.0 ng mL−1 and 3.9 and 20.4 ng mL−1 for flavonoids and isoflavones, respectively. Intra-day and inter-day precision (C.V., %) was less than 3.9% and 3.8%, respectively, and accuracy was between 0.03% and 5.0%. Recovery was 70.35–96.58%. The method is very rapid, simple, and reliable, and suitable for pharmacokinetic analysis. It can be routinely used for simultaneous determination of these five isoflavones and seven flavonoids in human urine. The method can also be applied to studies after administration of pharmaceutical preparations containing isoflavones and flavonoids to humans
Protein Kinase A Binds and Activates Heat Shock Factor 1
BACKGROUND. Many inducible transcription factors are regulated through batteries of posttranslational modifications that couple their activity to inducing stimuli. We have studied such regulation of Heat Shock Factor 1 (HSF1), a key protein in control of the heat shock response, and a participant in carcinogenisis, neurological health and aging. As the mechanisms involved in the intracellular regulation of HSF1 in good health and its dysregulation in disease are still incomplete we are investigating the role of posttranslational modifications in such regulation. METHODOLOGY/PRINCIPAL FINDINGS. In a proteomic study of HSF1 binding partners, we have discovered its association with the pleiotropic protein kinase A (PKA). HSF1 binds avidly to the catalytic subunit of PKA, (PKAca) and becomes phosphorylated on a novel serine phosphorylation site within its central regulatory domain (serine 320 or S320), both in vitro and in vivo. Intracellular PKAca levels and phosphorylation of HSF1 at S320 were both required for HSF1 to be localized to the nucleus, bind to response elements in the promoter of an HSF1 target gene (hsp70.1) and activate hsp70.1 after stress. Reduction in PKAca levels by small hairpin RNA led to HSF1 exclusion from the nucleus, its exodus from the hsp70.1 promoter and decreased hsp70.1 transcription. Likewise, null mutation of HSF1 at S320 by alanine substitution for serine led to an HSF1 species excluded from the nucleus and deficient in hsp70.1 activation. CONCLUSIONS. These findings of PKA regulation of HSF1 through S320 phosphorylation add to our knowledge of the signaling networks converging on this factor and may contribute to elucidating its complex roles in the stress response and understanding HSF1 dysregulation in disease.National Institutes of Health (2RO1CA047407, RO1CA077465
- …