86,773 research outputs found
Dose-rate dependence of swelling and damage in ion-irradiated nickel
No full textThe results of an irradiation experiment using 46 MeV Ni6+ ions from the Variable-Energy Cyclotron facility in Harwell are presented. The doserate was varied, at a constant total dose, by a factor of 20 and the damage produced examined in the peak region of damage and at smaller depths. The temperature range 450–700°C was investigated. It was found that the temperature dependence of swelling varies with both the doserate and the dose
Indication of an electron redistribution in the d band of Fe alloyed with Si
No full textTwo alloys of the Fe-Si system have been investigated by means of polarised neutron diffraction: a 7.5 at.% Si alloy and a 14.3 at.% Si alloy. The alloy of higher Si content showed some long-range order. For Fe925Si75 both the spherical and aspherical form factors were found to be equal within errors to those of pure Fe; for Fe857Si143 the magnetic moments and form factors were obtained for the three different sites. The Si site was found to have a form factor very different from that of pure Fe. The authors discuss these results and show that they are probably due to the contribution of the electrons at the bottom of 3d band states of Fe atoms when they occupy the Si site
Распределение магнитного момента в Fe−Ni сплавах. Эксперимент и вычисления
No full textThe magnetic structure factors of several ferromagnetic f.c.c. Fe−Ni alloys have been recently determined by means of the polarized-neutron technique in this and other laboratories. The amount of asphericity for each composition as determined by the population of thee g -sublevel was obtained from these measurements and these results are compared with a simple localized-electron model and with the predictions of coherent-potential approximation calculations. The agreement with these calculations is satisfactory
Local Antiferromagnetic Ordering in Ferromagnetic MnPt_{3} Alloys near the Stoichiometric Composition
No full textThe magnetic-moment density distribution in two alloys near the stoichiometric MnPt3 alloy composition has been measured by means of the polarized-neutron technique. It has been found that in the perfectly ordered lattice Mn and Pt atoms are ferromagnetically aligned, while in the presence of disorder the Mn atoms which happen to occupy the Pt sites give a negative contribution to the magnetization. The spherically averaged distribution for Mn atoms is independent of whether the atom is on a Mn or Pt site. However, Mn atoms on Mn sites are spherically symmetric, while Mn atoms on Pt sites have aspherical distributions
Concentration dependence of the phonon dispersion relations in substitutional fcc Co-Ni alloys
No full textThe concentration dependence of the phonon dispersion relations in fcc Co-Ni alloys have been determined by means of triple-axis spectrometry. Appreciable wave-vector-dependent frequency changes from pure Ni have been observed in this alloy system where practically no mass disorder is present because of the near-equal average mass of the costituents. The observed frequency shifts are discussed in connection with other experiments in similar alloy systems and with some estimates based on existing theories
Impaired alpha cell function in conditions with cortisol deficiency
No full textPlasma immunoreactive glucagon (IRG), insulin (IRI) and blood glucose (BG) were evaluated in the fasting state and during an arginine test (ATT) in 6 subjects with untreated hypopituitarism (H), in 2 hypopituitary subjects with normal cortisol production (H + C), in 3 subjects with Addison's disease (A) and in 14 normal volunteers (N). No increase in BG was observed in H and A after arginine, mean values being significantly lower than in N. Mean fasting and arginine-stimulated IRI levels were lower in H and A than in N; postabsorptive arginine-induced IRG levels were significantly reduced when compared to N. In contrast IRG levels in the two H + C patients were within the normal range. The impaired IRG production in A and in H (but not in H + C) suggests a close relationship between alpha pancreatic function and cortisol levels
Magnetic-moment distribution in ferromagnetic Fe-Cr alloys
No full textThe magnetic-moment distribution in disordered ferromagnetic bcc Fe3Cr has been determined by polarized-neutron diffraction. The measured magnetic structure factors, when compared with those of pure Fe obtained by Shull and co-workers and those for a Fe-Cr alloy of slightly smaller Cr content measured by Lander and Heaton, show an appreciably smaller asphericity. The composition dependence of the asphericity has been compared both with a localized-electron model and with calculations based on the coherent-potential approximation (CPA). The concentration dependences of the total spin magnetic moments, of the difference between the magnetic moments of the constituents, and of the density of states at the Fermi level are also compared with the CPA calculations. It is shown that the theory is able to reproduce the general trend of the experimental data in these alloys
Novel degradation products of oxasulfuron identified by capillary electrophoresis – mass spectrometry
No full textTwo new intermediates rising from the photolytic reaction of the sulfonylurea herbicide oxasulfuron have been identified in aqueous environment. The higher concentrations of the two derivatives oxetan-3-yl 2-(formilsulfamoyl) benzoate and N-(4,6-dimethylpyrimidin-2-yl) formamide were reached within 8 h of UVirradiation. Here we demonstrate that an optimal separation
and analysis of such compounds can be achieved by using
a novel analytical method based on “non-aqueous” capillary
electrophoresis (CE) system joined to an electrospray
ionisation-mass spectrometry equipment. Using such a separation
method and a particular electrophoretic solution a high reproducibility of migration times and peak areas can be obtained
Exaggerated glucagon secretion in diabetic and non-diabetic subjects with surgical porto-caval anastomosis
No full textPancreatic glucagon (IRG) levels in the postabsorptive (fasting) state and in response to arginine test (ATT), have been investigated in 17 subjects with porto-caval anastomosis (PCA). Out of these, seven subjects were insulin-treated diabetics, 5 were untreated diabetics, and 5 had no evidence of clinical diabetes. Basal and stimulated IRG values in the overall group of PCA subjects were significantly increased in comparison to 14 normal controls. No significant difference was found between the three groups of patients in respect to IRG values. The mean fasting IRG levels, grouped in relation to the age of shunt, were significantly raised six months after surgery. In addition no significant difference in IRG values (fasting or stimulated) was observed in relation to the entity of the liver disease (child degree) or to the type of surgical shunt. Finally, when PCA patients with or without encephalopathy were considered, fasting and peak IRG values were significantly increased in those patients with encephalopathy
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