3,675 research outputs found
Reactive belite stabilization mechanisms by boron-bearing dopants
Belite-rich cements hold promise for reduced energy consumption and CO2 emissions, but their use is hindered
by the slow hydration rates of ordinary belites. This drawback may be overcome by activation of belite
by doping. Here, the doping mechanism of B and Na/B in belites is reported. For B-doping, three solid solutions
have been tested: Ca2-x/2□x/2(SiO4)1-x(BO3)x, Ca2(SiO4)1-x(BO3)xOx/2 and Ca2-xBx(SiO4)1-x(BO4)x. The
experimental results support the substitution of silicate groups by tetrahedral borate groups with the concomitant
substitution of calcium by boron for charge compensation, Ca2-xBx(SiO4)1-x(BO4)x. Otherwise, the
coupled Na/B-doping of belite has also been investigated and Ca2-xNax(SiO4)1-x(BO3)x series is confirmed
to exist for a large range of x values. Along this series, α'H-C2S is the main phase (for x≥0.10) and is single
phase for x=0.25. Finally, a new structural description for borax doping in belite has been developed for
α'H-Ca1.85Na0.15(SiO4)0.85(BO3)0.15, which fits better borax activated belite cements in Rietveld mineralogical
analysisThis work has been supported by Spanish Ministry of Science and
Innovation through MAT2010-16213 research grant which is cofunded
by FEDER
Mechanism of stabilization of dicalcium silicate solid solution with aluminium
Stoichiometric dicalcium silicate, Ca2SiO4, displays a well-known polymorphism with temperature. When
this phase is doped by a range of elements, belite, one of the main phases of cements, is generated. Here,
we thoroughly study the aluminum doping of dicalcium silicate. This type of study is important for
cement characterization and also from a basic point of view. Ca2Si1−2xAl2xO4−x□x (x = 0, 0.010, 0.014,
0.03) has been prepared and studied by X-ray powder diffraction and the Rietveld method. The limiting
composition has been established as Ca2Si0.972Al0.028O3.986□0.014. The 27Al MAS NMR band located close
to ∼−70 ppm is ascribed to tetrahedral environments, in agreement with the proposed aliovalent Si/Al
atomic substitution mechanism. Thermal analysis measurements under a wet atmosphere indirectly
confirm the increase of oxygen vacancies as the amount of incorporated protons increases with the
aluminium content. A thorough electrical characterization has been carried out including overall conductivity
measurements under wet and dry atmospheres and conductivity as a function of the oxygen
partial pressure. The samples show oxide anion conductivity with a small p-type electronic contribution
under oxidizing conditions. These compounds display a very important proton contribution to the overall
conductivities under humidified atmospheres.This work has been supported by the Spanish Ministry of
Science and Innovation through the research grant MAT2010-
15175 which is co-founded by FEDER and Junta de Andalucía
(Spain) through the research grant P10-FQM-6680
Albumin-induced apoptosis of tubular cells is modulated by BASP1
Albuminuria promotes tubular injury and cell death, and is associated with faster progression of chronic kidney disease (CKD) to
end-stage renal disease. However, the molecular mechanisms regulating tubular cell death in response to albuminuria are not fully
understood. Brain abundant signal protein 1 (BASP1) was recently shown to mediate glucose-induced apoptosis in tubular cells.
We have studied the role of BASP1 in albumin-induced tubular cell death. BASP1 expression was studied in experimental
puromycin aminonucleoside-induced nephrotic syndrome in rats and in human nephrotic syndrome. The role of BASP1 in
albumin-induced apoptosis was studied in cultured human HK2 proximal tubular epithelial cells. Puromycin aminonucleoside
induced proteinuria and increased total kidney BASP1 mRNA and protein expression. Immunohistochemistry localized the
increased BASP1 to tubular cells. BASP1 expression colocalized with deoxynucleotidyl-transferase-mediated dUTP nick-end
labeling staining for apoptotic cells. Increased tubular BASP1 expression was observed in human proteinuric nephropathy by
immunohistochemistry, providing evidence for potential clinical relevance. In cultured tubular cells, albumin induced apoptosis
and increased BASP1 mRNA and protein expression at 6–48 h. Confocal microscopy localized the increased BASP1 expression
in albumin-treated cells mainly to the perinuclear area. A peripheral location near the cell membrane was more conspicuous in
albumin-treated apoptotic cells, where it colocalized with actin. Inhibition of BASP1 expression by a BASP1 siRNA protected from
albumin-induced apoptosis. In conclusion, albumin-induced apoptosis in tubular cells is BASP1-dependent. This information may
be used to design novel therapeutic approaches to slow CKD progression based on protection of tubular cells from the adverse
consequences of albuminuriaGrant support: FIS PS09/00447, PI13/00047, CP14/
00133, ISCIII-RETIC, REDinREN/RD06/0016/and RD012/0021 FEDER funds,
Comunidad de Madrid/CIFRA S2010/BMD-2378. Salary support: FIS to MDSN
and ABS (Miguel Servet), Beatriz Fernandez-Fernandez (Rio Hortega). Programa
Intensificación Actividad Investigadora (ISCIII/Agencia Laín-Entralgo/CM) to AO.
IIS-FJD Biobank RD09/0076/0010
Semantic Approach in Image Change Detection
International audienceChange detection is a main issue in various domains, and especially for remote sensing purposes. Indeed, plethora of geospatial images are available and can be used to update geographical databases. In this paper, we propose a classification-based method to detect changes between a database and a more recent image. It is based both on an efficient training point selection and a hierarchical decision process. This allows to take into account the intrinsic heterogeneity of the objects and themes composing a database while limiting false detection rates. The reliability of the designed framework method is first assessed on simulated data, and then successfully applied on very high resolution satellite images and two land-cover databases
FLAMES spectroscopy of low-mass stars in the young clusters sigma Ori and lambda Ori
Aims. We performed a detailed membership selection and studied the accretion
properties of low-mass stars in the two apparently very similar young (1-10
Myr) clusters sigma Ori and lambda Ori.
Methods. We observed 98 and 49 low-mass (0.2-1.0 M_sun) stars in sigma Ori
and lambda Ori respectively, using the multi-object optical spectrograph FLAMES
at the VLT, with the high-resolution (R=17,000) HR15N grating (6470-6790 AA).
We used radial velocities, Li and Halpha to establish cluster membership and
Halpha and other optical emission lines to analyze the accretion properties of
members.
Results. We identified 65 and 45 members of the sigma Ori and lambda Ori
clusters, respectively and discovered 16 new candidate binary systems. We also
measured rotational broadening for 20 stars and estimated the mass accretion
rates in 25 stars of the sigma Ori cluster, finding values between 10^-11 and
10^-7.7 M_sun yr^-1 and in 4 stars of the lambda Ori cluster, finding values
between 10^-11 and 10^-10.1 M_sun yr-1. Comparing our results with the infrared
photometry obtained by the Spitzer satellite, we find that the fraction of
stars with disks and the fraction of active disks is larger in the sigma Ori
cluster (52+-9% and 78+-16%) than in lambda Ori (28+-8% and 40+-20%)
Conclusions. The different disk and accretion properties of the two clusters
could be due either to the effect of the high-mass stars and the supernova
explosion in the lambda Ori cluster or to different ages of the cluster
populations. Further observations are required to draw a definitive conclusion.Comment: 14 pages, 9 figures, 9 tables, accepted for publications in A&
Peroxisome proliferator-activated receptor-β activation restores the high glucose-induced impairment of insulin signaling in endothelial cells
BACKGROUND AND PURPOSE: PPARβ enhances insulin sensitivity in adipocytes and skeletal muscle cells, but its effects on insulin signalling in endothelial cells are not known. We analysed the effects of the PPARβ/δ (PPARβ) agonists, GW0742 and L165041, on impaired insulin signalling induced by high glucose in HUVECs and aortic and mesenteric arteries from diabetic rats. EXPERIMENTAL APPROACH: Insulin-stimulated NO production, Akt-Ser(473) and eNOS-Ser(1177) phosphorylation, and reactive oxygen species (ROS) production were studied in HUVECs incubated in low- or high-glucose medium. Insulin-stimulated relaxations and protein phosphorylation in vessels from streptozotocin (STZ)-induced diabetic rats were also analysed. KEY RESULTS: HUVECs incubated in high-glucose medium showed a significant reduction in insulin-stimulated production of NO. High glucose also reduced insulin-induced Akt-Ser(473) and eNOS-Ser(1177) phosphorylation, increased IRS-1-Ser(636) and ERK1/2-Thr(183)-Tyr(185) phosphorylation and increased ROS production. The co-incubation with the PPARβ agonists GW0742 or L165041 prevented all these effects induced by high glucose. In turn, the effects induced by the agonists were suppressed when HUVEC were also incubated with the PPARβ antagonist GSK0660, the pyruvate dehydrogenase kinase (PDK)4 inhibitor dichloroacetate or after knockdown of both PPARβ and PDK4 with siRNA. The ERK1/2 inhibitor PD98059, ROS scavenger catalase, inhibitor of complex II thenoyltrifluoroacetone or uncoupler of oxidative phosphorylation, carbonyl cyanide m-chlorophenylhydrazone, also prevented glucose-induced insulin resistance. In STZ diabetic rats, oral GW0742 also improved insulin signalling and the impaired NO-mediated vascular relaxation. CONCLUSION AND IMPLICATIONS: PPARβ activation in vitro and in vivo restores the endothelial function, preserving the insulin-Akt-eNOS pathway impaired by high glucose, at least in part, through PDK4 activation
Nutrition Strategies for Triathlon
Contemporary sports nutrition guidelines recommend that each athlete develop a personalised, periodised and practical approach to eating that allows him or her to train hard, recover and adapt optimally, stay free of illness and injury and compete at their best at peak races. Competitive triathletes undertake a heavy training programme to prepare for three different sports while undertaking races varying in duration from 20 min to 10 h. The everyday diet should be adequate in energy availability, provide CHO in varying amounts and timing around workouts according to the benefits of training with low or high CHO availability and spread high-quality protein over the day to maximise the adaptive response to each session. Race nutrition requires a targeted and well-practised plan that maintains fuel and hydration goals over the duration of the specific event, according to the opportunities provided by the race and other challenges, such as a hot environment. Supplements and sports foods can make a small contribution to a sports nutrition plan, when medical supplements are used under supervision to prevent/treat nutrient deficiencies (e.g. iron or vitamin D) or when sports foods provide a convenient source of nutrients when it is impractical to eat whole foods. Finally, a few evidence-based performance supplements may contribute to optimal race performance when used according to best practice protocols to suit the triathlete’s goals and individual responsiveness
NOMAD spectrometer on the ExoMars trace gas orbiter mission: part 2—design, manufacturing, and testing of the ultraviolet and visible channel
NOMAD is a spectrometer suite on board the ESA/Roscosmos ExoMars Trace Gas Orbiter, which launched in March 2016. NOMAD consists of two infrared channels and one ultraviolet and visible channel, allowing the instrument to perform observations quasi-constantly, by taking nadir measurements at the day- and night-side, and during solar occultations. Here, in part 2 of a linked study, we describe the design, manufacturing, and testing of the ultraviolet and visible spectrometer channel called UVIS. We focus upon the optical design and working principle where two telescopes are coupled to a single grating spectrometer using a selector mechanism
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