9 research outputs found
Italian multicenter validation of cystic fibrosis questionnaire-R by A.L.Quittner and coll.
No full text
Characterization of the Interface in Rubber/Silica Composite Materials
No full textAbstract: in the rubber industry, especially tyre production, the most widely used elastomer is styrene-butadiene rubber (SBR) in which the styrene units generally are present at 25 wt.%. The unit repeats are random distributed along the macromolecular chains and the configuration of the butadiene units is mostly 1,4-trans. The elastomer blends are mixed with fillers, acting as reinforcing agents, and the effect that silica particles have on their physical and mechanical properties is now well established. One of the most important parameters in determining the performance of such composite materials is the degree of adhesion at the rubber/silica interface. In this context, the interface characterization has been performed through a spectroscopic investigation (XPS/x-ray-induced Auger electron spectroscopy) in order to derive information from core-level and Auger line chemical shifts. A series of composite rubbers have been examined by means of a detailed curve-fitting procedure that allows the determination of intrinsic and extrinsic structures connected to each photopeak and the spectroscopic results compared with those of reference compounds. The changes in the C 1s lineshape and shake-up region of the polymers and the reduced binding energies of silicon, oxygen and sulphur core lines have provided clear evidence of interfacial reactions. Moreover, the Auger parameters of silicon show systematic shifts that can be interpreted on a chemical state plot in terms of initial- and final-state contributions and used for theoretical investigation of the local chemical environment. Copyright (C) 2002 John Wiley Sons, Ltd
Renovascular disease and hypertension in children with neurofibromatosis
No full textNeurofibromatosis type 1 (NF1) is associated with vascular lesions, such as renal artery stenosis, and secondary hypertension. The real prevalence is largely unknown, particularly in children. We observed 27 patients with NF1, mean age 12.8 years (range 4.2-24 years), for 2-10 years to assess the association of NF1 with vascular abnormalities and secondary hypertension. Patients were studied with angiography, 24-h blood pressure monitoring, a captopril test, and Doppler ultrasonography of aorta and renal arteries. The prevalence of hypertension was 18.5%; 61.5% of patients studied with angiography had vascular lesions, half of whom were apparently normotensive. However, they had abnormal 24-h blood pressure monitoring, which was a first sign of poor blood pressure control. Those patients with severe hypertension (11.1%) were successfully treated with percutaneous transluminal angioplasty (PTA); stenosis recurred in 2 of 3 patients after a 2-year follow-up period, and was responsive to drugs. We conclude that hypertension is a frequent complication of NF1 in pediatric patients, it is usually secondary to typical vascular lesions, and requires careful follow-up. Ambulatory blood pressure monitoring (24-h) is a sensitive method for detecting initial alterations of the blood pressure pattern. PTA may be an effective treatment in this conditio
Ge-on-Si single-photon avalanche diode detectors: design, modeling, fabrication, and characterization at wavelengths 1310 and 1550 nm
No full textThe design, modeling, fabrication, and characterization of single-photon avalanche diode detectors with an epitaxial Ge absorption region grown directly on Si are presented. At 100 K, a single-photon detection efficiency of 4% at 1310 nm wavelength was measured with a dark count rate of ~ 6 megacounts/s, resulting in the lowest reported noise-equivalent power for a Ge-on-Si single-photon avalanche diode detector (1×10-14 WHz-1/2). The first report of 1550 nm wavelength detection efficiency measurements with such a device is presented. A jitter of 300 ps was measured, and preliminary tests on after-pulsing showed only a small increase (a factor of 2) in the normalized dark count rate when the gating frequency was increased from 1 kHz to 1 MHz. These initial results suggest that optimized devices integrated on Si substrates could potentially provide performance comparable to or better than that of many commercially available discrete technologies
