231 research outputs found
From: Trash to resource: Recovered-Pd from spent three-way catalysts as a precursor of an effective photo-catalyst for H2 production
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
Design, Performance and Series Production of Superconducting Trim Quadrupoles for the Large Hadron Collider
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
Growing CeO2 Nanoparticles Within the Nano-Porous Architecture of the SiO2 Aerogel
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
Force field for halide and alkali ions in water based on single-ion and ion-pair thermodynamic properties for a wide range of concentrations
Magnetic study of cufe2o4‐sio2 aerogel and xerogel nanocomposites
CuFe2O4 is an example of ferrites whose physico‐chemical properties can vary greatly at the nanoscale. Here, sol‐gel techniques are used to produce CuFe2O4‐SiO2 nanocomposites where copper ferrite nanocrystals are grown within a porous dielectric silica matrix. Nanocomposites in the form of both xerogels and aerogels with variable loadings of copper ferrite (5 wt%, 10 wt% and 15 wt%) were synthesized. Transmission electron microscopy and X‐ray diffraction investigations showed the occurrence of CuFe2O4 nanoparticles with average crystal size ranging from a few nanometers up to around 9 nm, homogeneously distributed within the porous silica matrix, after thermal treatment of the samples at 900 °C. Evidence of some impurities of CuO and α‐Fe2O3 was found in the aerogel samples with 10 wt% and 15 wt% loading. DC magnetometry was used to investigate the magnetic properties of these nanocomposites, as a function of the loading of copper ferrite and of the porosity characteristics. All the nanocomposites show a blocking temperature lower than RT and soft magnetic features at low temperature. The observed magnetic parameters are interpreted taking into account the occurrence of size and interaction effects in an ensemble of superparamagnetic nanoparticles distributed in a matrix. These results highlight how aerogel and xerogel matrices give rise to nanocomposites with different magnetic features and how the spatial distribution of the nanophase in the matrices modifies the final magnetic properties with respect to the case of conventional unsupported nanoparticles
Appropriate management of growth hormone deficiency during the age of transition: an Italian Delphi consensus statement
No abstract availabl
Energy transfer within the hydrogen bonding network of water following resonant terahertz excitation
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
Relationship of CYP21A2 genotype and serum 17-hydroxyprogesterone and cortisol levels in a large cohort of Italian children with premature pubarche.
ObjectivePremature pubarche (PP) is the most frequent sign of nonclassic congenital adrenal hyperplasia (NCCAH) due to 21-hydroxylase deficiency in childhood. The aim of this study was to assess the relationship between the CYP21A2 genotype and baseline and ACTH-stimulated 17-hydroxyprogesterone (17-OHP) and cortisol serum levels in patients presenting with PP.Patients and methodsA total of 152 Italian children with PP were studied. Baseline and ACTH-stimulated 17-OHP and cortisol serum levels were measured and CYP21A2 gene was genotyped in all subjects.ResultsBaseline and ACTH-stimulated serum 17-OHP levels were significantly higher in NCCAH patients than in both heterozygotes and children with idiopathic PP (IPP). Of the patient population, four NCCAH patients (7.3%) exhibited baseline 17-OHP values <2 ng/ml (6 nmol/l). An ACTH-stimulated 17-OHP cutoff level of 14 ng/ml (42 nmol/l) identified by the receiver-operating characteristics curves showed the best sensitivity (90.9%) and specificity (100%) in distinguishing NCCAH patients. This value, while correctly identifying all unaffected children, missed 9% of affected individuals. Cortisol response to ACTH stimulation was <18.2 μg/dl (500 nmol/l) in 14 NCCAH patients (28%) and none of the heterozygotes or IPP children. Among the 55 NCCAH patients, 54.5% were homozygous for mild CYP21A2 mutations, 41.8% were compound heterozygotes for one mild and one severe CYP21A2 gene mutations, and 3.6% had two severe CYP21A2 gene mutations.ConclusionIn children with PP, baseline 17-OHP levels are not useful to rule out the diagnosis of NCCAH, which is accomplished by means of ACTH testing only. The different percentages of severe and mild CYP21A2 gene mutations found in PP children compared with adult NCCAH patients is an indirect evidence that the enzyme defect is under-diagnosed in childhood, and it might not lead to the development of hyperandrogenic symptoms in adulthood. Stress-dose glucocorticoids should be considered in patients with suboptimal cortisol response to ACTH stimulation.</jats:sec
Accuracy and limitations of the growth hormone (GH) releasing hormone-arginine retesting in young adults with childhood-onset GH deficiency
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
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
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