187 research outputs found

    Growing CeO2 Nanoparticles Within the Nano-Porous Architecture of the SiO2 Aerogel

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    In this study, new CeO2-SiO2 aerogel nanocomposites obtained by controlled growth of CeO2 nanoparticles within the highly porous matrix of a SiO2 aerogel are presented. The nanocomposites have been synthesized via a sol-gel route, employing cerium (III) nitrate as the CeO2 precursor and selected surfactants to control the growth of the CeO2 nanoparticles, which occurs during the supercritical drying of the aerogels. Samples with different loading of the CeO2 dispersed phase, ranging from 5 to 15%, were obtained. The nanocomposites showed the morphological features typical of the SiO2 aerogels such as open mesoporosity with surface area values up to 430 m2·g−1. TEM and XRD characterizations show that nanocrystals of the dispersed CeO2 nanophase grow within the aerogel already during the supercritical drying process, with particle sizes in the range of 3 to 5 nm. TEM in particular shows that the CeO2 nanoparticles are well-distributed within the aerogel matrix. We also demonstrate the stability of the nanocomposites under high temperature conditions, performing thermal treatments in air at 450 and 900°C. Interestingly, the CeO2 nanoparticles undergo a very limited crystal growth, with sizes up to only 7 nm in the case of the sample subjected to a 900°C treatment

    From: Trash to resource: Recovered-Pd from spent three-way catalysts as a precursor of an effective photo-catalyst for H2 production

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    The successful production of a nanostructured and highly dispersed Pd-TiO2 photo-catalyst, using [Pd(Me2dazdt)2](I3)2 (Me2dazdt = N,N\u2032-dimethyl-perhydrodiazepine-2,3-dithione) salt, obtained through the selective and safe recovery of palladium from model exhaust three-way catalysts (TWCs), is reported here. The photo-catalyst prepared by the impregnation/photo-reduction of palladium on the support showed improved performance in H2 production from methanol and in glycerol photo-reforming compared to reference photo-catalysts obtained from conventional Pd-salts. The reported results represent a case of successful palladium \u201crecovery and re-employment\u201d and thus constitute an example of green chemistry by providing, in one route, the environmentally friendly recovery of a critical metal and its employment in the renewable energy field

    Energy transfer within the hydrogen bonding network of water following resonant terahertz excitation

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    Energy dissipation in water is very fast and more efficient than in many other liquids. This behavior is commonly attributed to the intermolecular interactions associated with hydrogen bonding. Here, we investigate the dynamic energy flow in the hydrogen bond network of liquid water by a pump-probe experiment. We resonantly excite intermolecular degrees of freedom with ultrashort single-cycle terahertz pulses and monitor its Raman response. By using ultrathin sample cell windows, a background-free bipolar signal whose tail relaxes monoexponentially is obtained. The relaxation is attributed to the molecular translational motions, using complementary experiments, force field, and ab initio molecular dynamics simulations. They reveal an initial coupling of the terahertz electric field to the molecular rotational degrees of freedom whose energy is rapidly transferred, within the excitation pulse duration, to the restricted translational motion of neighboring molecules. This rapid energy transfer may be rationalized by the strong anharmonicity of the intermolecular interactions

    A post-weaning obesogenic diet exacerbates the detrimental effects of maternal obesity on offspring insulin signaling in adipose tissue

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    Previous studies have shown that maternal diet-induced obesity leads to increased risk of type 2 diabetes in offspring. The current study investigated if weaning onto an obesogenic diet exaggerated the detrimental effects of maternal diet-induced obesity in adipose tissue. Maternal obesity and offspring obesity led to reduced expression of key insulin signalling proteins, including insulin receptor substrate-1 (IRS-1). The effects of maternal obesity and offspring obesity were, generally, independent and additive. Irs1 mRNA levels were similar between all four groups of offspring, suggesting that in both cases post-transcriptional regulation was involved. Maternal diet-induced obesity increased miR-126 expression however levels of this miR were not influenced by a post-weaning obesogenic diet. In contrast, a post-weaning obesogenic diet was associated with increased levels of suppressor of cytokine signaling-1, implicating increased degradation of IRS-1 as an underlying mechanism. Our results suggest that whilst programmed reductions in IRS-1 are associated with increased levels of miR-126 and consequently reduced translation of Irs1 mRNA, the effects of a post-weaning obesogenic diet on IRS-1 are mediated by miR-126 independent mechanisms, including increased IRS-1 protein degradation. These divergent mechanisms explain why the combination of maternal obesity and offspring obesity leads to the most pronounced effects on offspring metabolism.The. Medical Research Council (MC_UU_12012/4), Biotechnology and Biological Sciences Research Council (BB/M001636/1), British Heart Foundation (PG/14/20/30769) and São Paulo Research Foundation (2014/17012-4 and 2014/20380-5) supported this research

    Design, Performance and Series Production of Superconducting Trim Quadrupoles for the Large Hadron Collider

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    The Large Hadron Collider (LHC) will be equipped with several thousands of superconducting corrector magnets. Among the largest ones are the superconducting trim quadrupoles (MQTL). These twin-aperture magnets with a total mass of up to 1700 kg have a nominal gradient of 129 T/m at 1.9 K and a magnetic length of 1.3 m. Sixty MQTL are required for the LHC, 36 operating at 1.9 K in and 24 operating at 4.5 K. The paper describes the design features, and reports the measured quench performance and magnetic field quality of the production magnets. The MQTL magnet production is shared between CERN and industry. This sharing is simplified due to the modular construction, common to all twin-aperture correctors

    Accuracy and limitations of the growth hormone (GH) releasing hormone-arginine retesting in young adults with childhood-onset GH deficiency

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    Background: Re-testing for GH secretion is needed to confirm the diagnosis of GH deficiency (GHD) after adult height achievement in childhood-onset GHD (COGHD). Aim: To define the cut-off of GH peak after retesting with GH-releasing hormone plus arginine (GHRHarg) in the diagnosis of permanent GHD in COGHD of different etiology. Patients and methods: Eighty-eight COGHD (median age 17.2 y), 29 idiopathic GHD (IGHD), 44 cancer survivors (TGHD) and 15 congenital GHD (CGHD) were enrolled in the study; 54 had isolated GHD (iGHD) and 34 had multiple pituitary hormone deficiencies (MPHD). All were tested with insulin tolerance test (ITT) and GHRHarg. IGHD with a GH response to ITT 656\ub5g/L were considered true negatives and served as the control group, and patients with a GH response <6\ub5g/L as true positives. Baseline IGF-I was also measured. The diagnostic accuracy of GHRHarg testing and of IGF-I SDS in patients with GHD of different etiologies was evaluated by ROC analysis. Results: Forty-six subjects with a GH peak to ITT 656\ub5g/L and 42 with GH peak <6 \ub5g/L showed a GH peak after GHRHarg between 8.8\u2013124\ub5g/L and 0.3\u201326.3\ub5g/L, respectively; 29 IGHD were true negatives, 42 were true positives and 17 with a high likelihood GHD showed a GH peak to ITT 656\ub5g/L. ROC analysis based on the etiology indicated the best diagnostic accuracy for peak GH cutoffs after GHRHarg of 25.3 \ub5g/L in CGHD, 15.7 in TGHD, and 13.8 in MPHD, and for IGF-1 SDS at 122.1 in CGHD, 121.5 in TGHD, and 121.9 in MPHD. Conclusions: Our findings indicate that the best cut-off for GH peak after retesting with GHRHarg changes according to the etiology of GHD during the transition age. Based on these results the diagnostic accuracy of GHRHarg remains questionable

    Safety outcomes during pediatric GH therapy: final results from the prospective GeNeSIS observational program

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    CONTEXT: Safety concerns regarding premature mortality, diabetes, neoplasia and cerebrovascular disease in association with growth hormone (GH) therapy have been raised. OBJECTIVE: To assess incidence of key safety outcomes. DESIGN: Prospective, multinational, observational study (1999-2015). SETTING: 22,311 GH-treated children from 827 investigative sites in 30 countries. PATIENTS: Children with growth disorders. INTERVENTIONS: GH treatment. MAIN OUTCOME MEASURES: Standardized mortality (SMR) and incidence (SIR) ratios with 95% confidence intervals (CI) for mortality, diabetes, and primary cancer, using general population registries. RESULTS: Predominant short stature diagnoses were GH deficiency (63%), idiopathic short stature (13%), and Turner syndrome (8%), with mean±SD follow-up of 4.2±3.2 years (∼92,000 person-years [PY]). Forty-two deaths occurred in patients with follow-up, with SMR (95% CI) of 0.61 (0.44-0.82); the SMR was elevated for patients with cancer-related organic GH deficiency (5.87 [3.21-9.85]). Based on 18 cases, Type 2 diabetes (T2DM) risk was elevated (SIR 3.77 [2.24-5.96]), but 72% had risk factors. In patients without cancer history, 14 primary cancers were observed (SIR 0.71 [0.39-1.20]). Second neoplasms occurred in 31/622 (5.0%) cancer survivors (10.7 [7.5-15.2] cases/1000 PY), and intracranial tumor recurrences in 67/823 (8.1%) tumor survivors (16.9 [13.3-21.5] cases/1000 PY). All 3 hemorrhagic stroke cases had risk factors. CONCLUSIONS: GeNeSIS data support the favourable safety profile of pediatric GH treatment. Overall risk for death or primary cancer was not elevated in GH-treated children, and no hemorrhagic strokes occurred in patients without risk factors. T2DM incidence was elevated compared to the general population, but most cases had diabetes risk factors

    Exercise rescues obese mothers' insulin sensitivity, placental hypoxia and male offspring insulin sensitivity

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    The prevalence of obesity during pregnancy continues to increase at alarming rates. This is concerning as in addition to immediate impacts on maternal wellbeing, obesity during pregnancy has detrimental effects on the long-term health of the offspring through non-genetic mechanisms. A major knowledge gap limiting our capacity to develop intervention strategies is the lack of understanding of the factors in the obese mother that mediate these epigenetic effects on the offspring. We used a mouse model of maternal-diet induced obesity to define predictive correlations between maternal factors and offspring insulin resistance. Maternal hyperinsulinemia (independent of maternal body weight and composition) strongly associated with offspring insulin resistance. To test causality, we implemented an exercise intervention that improved maternal insulin sensitivity without changing maternal body weight or composition. This maternal intervention prevented excess placental lipid deposition and hypoxia (independent of sex) and insulin resistance in male offspring. We conclude that hyperinsulinemia is a key programming factor and therefore an important interventional target during obese pregnancy, and propose moderate exercise as a promising strategy to improve metabolic outcome in both the obese mother and her offspring.This work received funding from the European Union’s Seventh Framework Programme [FP7/2007-2013, project EarlyNutrition, grant agreement n°289346]; the MRC Metabolic Diseases Unit award [MC_UU_12012/4]; the Biotechnology and Biological Sciences Research Council [BB/M001636/1]; the British Heart Foundation (PG/14/20/30769) and the São Paulo Research Foundation (Process number: 2014/20380-5)
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