41 research outputs found
Effect of the substitution of M2O3 (M = La, Y, In, Ga, Al) for CaO on the bioactivity of 2.5CaO center dot 2SiO(2) glass
No full textGlasses were prepared whose compositions are defined by the following general formula: (2.5-x)CaO .x/3M(2)O(3). 2SiO(2) (0 less than or equal to x less than or equal to 0.6) (M = Ga, Al, In). Their bioactivity Was Studied "in vitro" by soaking the glasses in a simulated body fluid (SBF) The consequent formation of calcium phosphate laver was studied by means of electron microscopy (EM) equipped with an energy-dispersive system (EDS) for elemental analysis and Infrared (IR) spectroscopy. The results are compared to the literature relative to the Substitution of La2O3 and Y2O3 for CaO. It is observed that. in general, the substitution of M2O3 for CaO in the binary CaO-SiO2 glass composition progressively reduces the ability to form a calcium phosphate layer on the surfaces exposed to simulated body fluid (SBF). The composition limit can be related to the ionic field strength of the substituting cation and to the CaO content of the base glass. According to the mechanism reported in the literature a silica gel-like surface layer initially forms on the surfaces exposed to SBF. The observed results can be attributed to the effect of the Substitution of M2O3 for CaO on the acidic properties of the silanolic groups. (C) 2001 Elsevier Science Ltd. All rights reserved
T-g and FTIR of (2.5-x)CaO. x/3M2O3. 2SiO(2) (M = Y, La, In, Al, Ga) glasses
No full textA comparative study of the effect of substituting oxides of (M = Y, La, In, Al, Ga) to CaO in 2.5CaO2SiO(2) glass in the narrow compositional range of the binary CaO-SiO2 system in which homogeneous glasses can be obtained (0.4 < CaO/(CaO + SiO2) < 0.55). A plot of glass transformation temperature, T-g, vs the ionic field strength, Z/r(2), where Z and r are the charge and the radius of the cation, is useful in discussing the role of oxides in the glassy structure. It is hypothesized that, in the composition range, studied Al2O3 and Ga2O3 act as network forming oxides, while La2O3, Y2O3 and In2O3 act as network modifying oxides. FTIR spectra agree with this hypothesis and with the expectations based on the criteria reported in the literature, in particular with the one proposed by McMillan that the network modifier cations have an ionic field strength Z/r(2) < 5 A(-2). (C) 1999 Elsevier Science B.V. All rights reserved
Inflation-Based Fiscal Consolidation: Does Speed Matter?
No full textThe potential role that a permanent increase in the inflation target might have in contributing to debt consolidation has rarely been covered in the literature on the link
between inflation and public debt. This paper thus investigates under what conditions
a higher inflation target might lead to a reduction in the public debt-to-GDP ratio,
in a deterministic environment of a TANK model where monetary and fiscal authorities actively operate. Analysing the economic mechanisms involved led to two key
results. Higher inflation has opposite effects on public debt in the short and long term.
Initially, a rise in the nominal interest rate induces savers to invest relatively more
in bonds. In contrast, once the inflation rate reaches higher values, lower wages and
rates of return impact on savers who reduce investments in bonds. The second finding
is that fiscal consolidation through higher inflation is far from obvious. Overall, the
long-term negative effects of higher inflation on output determine increases in fiscal
deficits. Moreover, a slower inflation adjustment path influences households’ expectations, leading to increases in the debt-to-GDP ratio rather than decreases in the short
term. In light of that, today more than ever, a traditional fiscal policy aimed at reducing the government’s deficit would be needed. Furthermore, revising the monetary policy strategy to increase the inflation target would not be recommended due to the potentially negative effects higher inflation could have on the economy
Effects on the thermal properties and bioactivity of substitution of CaO by M2O3 (M = La, Y, Al) in wollastonite glass
No full textThe effects on the thermal properties and bioactivity of the substitution of CaO by La2O3, Y2O3 and Al2O3 in a glass of composition CaO.SiO2 were studied and compared. The trivalent metal oxides were all effective in raising the glass transformation and softening temperatures when they replaced CaO in the glass of composition CaO.SiO2. The experimental results suggest that Al2O3 plays the role of a glass-former, while La2O3 and Y2O3 behave as glass-modifiers. The tendency to devitrify appears to be the lower, the farther the glass composition is from those of the crystalline phases, owing to the need for diffusion over longer distances, the greater the composition difference. The substitution with the trivalent metal oxides is detrimental to the bioactivity, which is preserved only in the event of very small degrees of substitution. The most negative role appears to be played by Al2O3
New strategy for testing new high nitrogen bearing steel for offshore wind turbines
No full textThis article presents some results obtained during the first stage of the European Union project titled “STEELWIND,” a part of which has been dedicated to roller–race contact dynamics. Contact has been modeled qualitatively using viscous-elastic friction, in the sliding regions, and hysteresis-modified Hertzian pressure in the whole contact zone. Slip and stick areas are detected within the contact area where the sliding velocity may have both opposite directions parallel to the entraining velocity. Considering the complexity of the hybrid rolling–sliding–sticking conditions, the developed model, although simplified, can be helpful to develop a sliding–rolling test by means of a standard reciprocator stand, where nonsymmetrical and mobile configurations of the testing race samples are introduced
Effects on the Thermal Properties and Bioactivity of Substitution of CaO by M2O3 (M=La, Y, Al) in Wollastonite Glass
No full textOptimized coating procedure for the protection of TiAl intermetallic alloy against high temperature oxidation
No full text"The interest for TiAl intermetallic alloys is growing in the last years because of their excellent. ratio between mechanical properties and density. However, the application at temperatures up to 873-. 973 K is restricted by the resistance to oxidation. For this reason it is of great importance to study. protective coatings able to raise its temperature of performance above 1073 K.. A TiAl3 layer was obtained on the surface of Ti-Al intermetallic samples, depositing an Al coating by. arc Physical Vapour Deposition, followed by a thermal treatment. The microstructure and the. composition of the coating were characterised before and after the thermal treatment by Scanning. Electron Microscopy, X-Ray Diffraction, Focused Ion Beam and Glow Discharge Optical Emission. Spectroscopy. The mechanical behaviour of the thermal treated layer was investigated by means of. scratch tests and nano-indentation.. Static oxidations at 1123 K were carried out on coated and uncoated samples, in order to study the. effect of the coating on the oxidation resistance of the samples. The aluminide coating provides a. protection against oxidation in air at the considered temperatures due to its ability to form a. continuous Al2O3 scale on the surface by the transformation of TiAl3 in TiAl2.
Economic burden of pneumococcal disease in children in Liguria, Italy
No full textVaccinations against Streptococcus pneumoniae are included in infant immunization programs globally. However, a substantial burden due to pneumococcal disease (PD) remains. This study aimed to estimate the cost of emergency department (ED) visits and hospitalizations associated with invasive pneumococcal disease, all-cause pneumonia, and acute otitis media in children <15 years of age in the Liguria region of Italy between 2012 and 2018. The retrospective cohort study used data from the Liguria Region Administrative Health Databases and the Ligurian Chronic Condition Data Warehouse, which contain information on hospital stays, outpatient visits, laboratory/imaging techniques, surgical procedures, and pharmaceutical prescriptions. Patients with one or more ED or inpatient claim for PD (based on International Classification of Diseases, Ninth Revision, Clinical Modification codes) were included. Cost of ED visits and hospitalizations were estimated from the diagnosis-related group system and procedures performed in the ED. In Ligurian children <15 years of age during 2012–2018, the median annual number of hospitalizations plus ED visits due to PD was 4,009, and the median estimated annual cost was €3.6 million. All-cause pneumonia accounted for the majority of hospitalization costs during the study period. Number and costs of ED visits and hospitalizations increased from 2012 to 2018. Despite widespread infant immunization in Liguria, economic costs due to PD-associated ED visits and hospitalizations remained high in children 0–14 years of age
Atrial natriuretic factor: localization in the adrenal gland of the lizard Podarcis sicula and effects on pituitary-adrenal axis activity
No full textNeuropeptide Y (NPY) modulates pituitary-adrenal axis activity in the lizard, Podarcis sicula.
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