546 research outputs found
Electrochemical synthesis of ammonia from N2 and H2O based on (Li,Na,K)2CO3-Ce0.8Gd 0.18Ca0.02O2-δ composite electrolyte and CoFe2O4 cathode
Electrochemical synthesis of ammonia from water vapour and nitrogen was investigated using an electrolytic cell based on CoFe2O 4-Ce0.8Gd0.18Ca0.02O 2-δ (CFO-CGDC), CGDC-ternary carbonate composite and Sm 0.5Sr0.5CoO3-δ-Ce0.8Gd 0.18Ca0.02O2-δ (SSCo-CGDC) as cathode, electrolyte and anode respectively. CoFe2O4, CGDC and SCCo were prepared via a combined EDTA-citrate complexing sol-gel and characterised by X-ray diffraction (XRD). The AC ionic conductivities of the CGDC-carbonate composite were investigated under three different atmospheres (air, dry O 2 and wet 5% H2-Ar). A tri-layer electrolytic cell was fabricated by a cost-effective one-step dry-pressing and co-firing process. Ammonia was successfully synthesised from water vapour and nitrogen under atmospheric pressure and the maximum rate of ammonia production was found to be 6.5 × 10-11 mol s-1 cm-2 at 400 C and 1.6 V which is two orders of magnitude higher than that of previous report when ammonia was synthesised from N2 and H2O at 650 C
Primary aldosteronism: molecular medicine meets public health.
Primary aldosteronism is the most common single cause of hypertension and is potentially curable when only one adrenal gland is the culprit. The importance of primary aldosteronism to public health derives from its high prevalence but huge under-diagnosis (estimated to be <1% of all affected individuals), despite the consequences of poor blood pressure control by conventional therapy and enhanced cardiovascular risk. This state of affairs is attributable to the fact that the tools used for diagnosis or treatment are still those that originated in the 1970-1990s. Conversely, molecular discoveries have transformed our understanding of adrenal physiology and pathology. Many molecules and processes associated with constant adrenocortical renewal and interzonal metamorphosis also feature in aldosterone-producing adenomas and aldosterone-producing micronodules. The adrenal gland has one of the most significant rates of non-silent somatic mutations, with frequent selection of those driving autonomous aldosterone production, and distinct clinical presentations and outcomes for most genotypes. The disappearance of aldosterone synthesis and cells from most of the adult human zona glomerulosa is the likely driver of the mutational success that causes aldosterone-producing adenomas, but insights into the pathways that lead to constitutive aldosterone production and cell survival may open up opportunities for novel therapies
Genome landscapes and bacteriophage codon usage
Across all kingdoms of biological life, protein-coding genes exhibit unequal
usage of synonmous codons. Although alternative theories abound, translational
selection has been accepted as an important mechanism that shapes the patterns
of codon usage in prokaryotes and simple eukaryotes. Here we analyze patterns
of codon usage across 74 diverse bacteriophages that infect E. coli, P.
aeruginosa and L. lactis as their primary host. We introduce the concept of a
`genome landscape,' which helps reveal non-trivial, long-range patterns in
codon usage across a genome. We develop a series of randomization tests that
allow us to interrogate the significance of one aspect of codon usage, such a
GC content, while controlling for another aspect, such as adaptation to
host-preferred codons. We find that 33 phage genomes exhibit highly non-random
patterns in their GC3-content, use of host-preferred codons, or both. We show
that the head and tail proteins of these phages exhibit significant bias
towards host-preferred codons, relative to the non-structural phage proteins.
Our results support the hypothesis of translational selection on viral genes
for host-preferred codons, over a broad range of bacteriophages.Comment: 9 Color Figures, 5 Tables, 53 Reference
X-Ray Spectroscopy of Stars
(abridged) Non-degenerate stars of essentially all spectral classes are soft
X-ray sources. Low-mass stars on the cooler part of the main sequence and their
pre-main sequence predecessors define the dominant stellar population in the
galaxy by number. Their X-ray spectra are reminiscent, in the broadest sense,
of X-ray spectra from the solar corona. X-ray emission from cool stars is
indeed ascribed to magnetically trapped hot gas analogous to the solar coronal
plasma. Coronal structure, its thermal stratification and geometric extent can
be interpreted based on various spectral diagnostics. New features have been
identified in pre-main sequence stars; some of these may be related to
accretion shocks on the stellar surface, fluorescence on circumstellar disks
due to X-ray irradiation, or shock heating in stellar outflows. Massive, hot
stars clearly dominate the interaction with the galactic interstellar medium:
they are the main sources of ionizing radiation, mechanical energy and chemical
enrichment in galaxies. High-energy emission permits to probe some of the most
important processes at work in these stars, and put constraints on their most
peculiar feature: the stellar wind. Here, we review recent advances in our
understanding of cool and hot stars through the study of X-ray spectra, in
particular high-resolution spectra now available from XMM-Newton and Chandra.
We address issues related to coronal structure, flares, the composition of
coronal plasma, X-ray production in accretion streams and outflows, X-rays from
single OB-type stars, massive binaries, magnetic hot objects and evolved WR
stars.Comment: accepted for Astron. Astrophys. Rev., 98 journal pages, 30 figures
(partly multiple); some corrections made after proof stag
Astrobiological Complexity with Probabilistic Cellular Automata
Search for extraterrestrial life and intelligence constitutes one of the
major endeavors in science, but has yet been quantitatively modeled only rarely
and in a cursory and superficial fashion. We argue that probabilistic cellular
automata (PCA) represent the best quantitative framework for modeling
astrobiological history of the Milky Way and its Galactic Habitable Zone. The
relevant astrobiological parameters are to be modeled as the elements of the
input probability matrix for the PCA kernel. With the underlying simplicity of
the cellular automata constructs, this approach enables a quick analysis of
large and ambiguous input parameters' space. We perform a simple clustering
analysis of typical astrobiological histories and discuss the relevant boundary
conditions of practical importance for planning and guiding actual empirical
astrobiological and SETI projects. In addition to showing how the present
framework is adaptable to more complex situations and updated observational
databases from current and near-future space missions, we demonstrate how
numerical results could offer a cautious rationale for continuation of
practical SETI searches.Comment: 37 pages, 11 figures, 2 tables; added journal reference belo
Implication of sperm RNAs in transgenerational inheritance of the effects of early trauma in mice.
Small non-coding RNAs (sncRNAs) are potential vectors at the interface between genes and environment. We found that traumatic stress in early life altered mouse microRNA (miRNA) expression, and behavioral and metabolic responses in the progeny. Injection of sperm RNAs from traumatized males into fertilized wild-type oocytes reproduced the behavioral and metabolic alterations in the resulting offspring.We thank M. Rassoulzadegan and V. Grandjean for help with the sperm
purification, F. Manuella and H. Hörster for assistance with the MSUS paradigm,
H. Welzl for help with behavior, G. Vernaz for help with western blotting,
R. Tweedie-Cullen and P. Nanni for help with mass spectrometry, A. Patrignani
for advice on DNA and RNA quality assessment, and A. Chen and A. Brunner for
constructive discussions. This work was supported by the Austrian Academy of
Sciences, the University of Zürich, the Swiss Federal Institute of Technology,
Roche, the Swiss National Science Foundation, and The National Center of
Competence in Research “Neural Plasticity and Repair”. P.S. was supported by a
Gonville and Caius College fellowship.This is the accepted manuscript. The final version is available in Nature Neuroscience 17, 667–669 (2014), doi:10.1038/nn.369
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The FIELDS Instrument Suite for Solar Probe Plus: Measuring the Coronal Plasma and Magnetic Field, Plasma Waves and Turbulence, and Radio Signatures of Solar Transients.
NASA's Solar Probe Plus (SPP) mission will make the first in situ measurements of the solar corona and the birthplace of the solar wind. The FIELDS instrument suite on SPP will make direct measurements of electric and magnetic fields, the properties of in situ plasma waves, electron density and temperature profiles, and interplanetary radio emissions, amongst other things. Here, we describe the scientific objectives targeted by the SPP/FIELDS instrument, the instrument design itself, and the instrument concept of operations and planned data products
The Evolution of Compact Binary Star Systems
We review the formation and evolution of compact binary stars consisting of
white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and
BHs are thought to be the primary astrophysical sources of gravitational waves
(GWs) within the frequency band of ground-based detectors, while compact
binaries of WDs are important sources of GWs at lower frequencies to be covered
by space interferometers (LISA). Major uncertainties in the current
understanding of properties of NSs and BHs most relevant to the GW studies are
discussed, including the treatment of the natal kicks which compact stellar
remnants acquire during the core collapse of massive stars and the common
envelope phase of binary evolution. We discuss the coalescence rates of binary
NSs and BHs and prospects for their detections, the formation and evolution of
binary WDs and their observational manifestations. Special attention is given
to AM CVn-stars -- compact binaries in which the Roche lobe is filled by
another WD or a low-mass partially degenerate helium-star, as these stars are
thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure
A pulmonary mass with invasion into the heart
We describe the case of a 58 year old woman who presented with bronchial atypical carcinoid found at surgery to invade the left atrium along the pulmonary veins. A right pneumonectomy and removal of a portion of the left atrium was performed. The patient made an excellent post operative recovery. Three years later she presented in acute respiratory failure secondary to local recurrence. This is first case described in which recurrence after resection of bronchial carcinoid metastatic to the heart is described
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