Renato Esposito

AMINOACID LOSS IN PERITONEAL DIALYSIS

Abstract In 8 peritoneal dialyses in seven patients aminoacid loss was found to average 4·963 g. per 27·25 litres exchanged. 20 aminoacids in the dialysate were individually identified and the amount of each present was measured. All the essential aminoacids measurable by this technique were present. The aminoacid loss was related to the volume of dialysate exchanged, and also to the protein content of the dialysate. It is recommended that both aminoacid and protein loss in repeated peritoneal dialysis be replenished by a high-protein intake corresponding to five whole eggs, preferably when the dialysis has terminated, or by parenteral plasma or aminoacid solutions; and that peritoneal dialysis be as short as possible.

Histidine for treatment of uraemic anaemia.

A group of 28 uraemic patients on dialysis treatment were given daily supplements of histidine by mouth. Plasma amino-acid concentration, plasma iron, serum transferrin, packed cell volume, and reticulocyte count were all measured before and after two months of histidine supplementation. The treatment raised the plasma histidine concentration and at the same time there was a rise in transferrin and iron levels and packed cell volume. Reticulocyte counts fell after two months of histidine supplementation.

Evaluation of energy release rate for delamination defects at the skin/stringer interface of a stiffened composite panel

Abstract This paper deals with numerical investigation on a stiffened composite panel under longitudinal compression load, in presence of artificial delamination defects between skin/stringer interface layers. At first, both the experimental and numerical non-linear equilibrium paths were determined, until the failure load value of the structure was reached. Then local evaluation of the energy release rate parameter was performed at defect front, by means of a hybrid (FEM/analytical) procedure based on a particularized virtual crack closure technique. The same FE shell model was used to perform both global and local calculations by means of a single analysis.

Cold Carbon Apparatus for Hemodialysis

A prototype of artificial kidney with regeneration of the dialysis fluid in active carbon at low temperature is presented. The data obtained through a series of simulated dialysis show that carbon adsorbs, besides creatinine and other compounds, urea in satisfactory quantities. Furthermore, the possibility of completely regenerating carbon with tap water washing makes the routine use of an artificial kidney based on a cold operating carbon depurator extremely practical.

Finite Element Analysis of Residual Stresses on Butt Welded Joints

Localized heating during welding, followed by rapid cooling, usually generates residual stresses in the weld and in the base metal. Residual stresses in welding processes give significant problems in the accurate manufacture of structures because those stresses heavily induce the formation of cracks in the fusion zone in high strength steels. Therefore, estimating the magnitude and distribution of welding residual stresses and characterizing the effects of certain welding conditions on the residual stresses are deemed necessary. In this work, residual stresses and distortions on butt welded joints are numerically evaluated by means of finite element method. The FE analysis allows to highlight and evaluate the stress field and his gradient around the fusion zone of welded joints, higher than any other located in the surrounding area. Temperature-dependent material properties, welding velocity, external mechanism constraints, technique of ‘element birth and death’ and latent heat of fusion are also taken into account. Some numerical results are compared with experimental data showing a very good correlation.© 2006 ASME

Finite Element Analysis of a Composite Bulkhead Structure

Reducing structural weight is one of the major ways to improve aircraft performance. Lighter and/or stronger materials allow greater range and speed and may also contribute to reducing operational costs. Nowadays composite materials are widely used in “primary” structural components such as fuselage, for which contrasting requirements like lightness and structural strength are required, so particular attention is necessary during its design. In this paper a composite front bulkhead, subjected to ultimate pressure load, was examined. The front bulkhead is made of a composite skin, stiffened with seven vertical stiffeners linked through metallic fittings; the whole system is joined to the fuselage by rivets. A Finite Element model was established: the used elements were four nodes shells, simulating composite layers, and two nodes bar elements, simulating rivets; the structure was clamped and a pressure load was applied to the skin. A linear static stress analysis was performed to calculate strains in particular points in which strain gauges or rosettes are placed: the numerical results, compared with experimental ones, show a good degree of correlation. Stress calculations were performed in order to verify the front and rear bulkhead structural safety.

Fatigue Test on a Full Scale Panel

Fatigue test on a full scale panel with complex loading and geometry has been carried out by using a tri-axial test machine located in the laboratory of the University of Naples. The aeronautical test panel was designed and manufactured by Alenia. The demonstrator is made up of two parts which are linked by a transversal joint that is parallel to the stringer direction. A fatigue load was applied in the normal direction to the longitudinal joint, while a constant load was applied in the joint direction. The full scale panel was equipped with strain gauges for deformation state measurements. Preliminary static load tests were performed in order to provide deformation measurements for numerical correlation. The outcomes confirmed that the applied load level is consistent with a linear elastic material behaviour. Three intermediate failures occurred before the final one: the first two under a clip, while in the third case a panel frame failed. Finally after about 177,000 cycles the demonstrator broke down. A non linear finite element analysis was also carried out in order to correlate failure events that occurred during the demonstrator testing.

Warm Compaction: FEM Analysis of Stress and Deformation States of Compacting Dies with Rectangular Profile of Various Aspect Ratio

The deformation under radial pressure of rectangular dies for metal powder compaction has been investigated by FEM. The explored variables have been: aspect ratio of die profile, ratio between diagonal of the profile and die height, insert and ring thickness, radius at die corners, interference, different insert materials, i. e. conventional HSS, HSS from powders, cemented carbide (10% Co). The analyses has ascertained the unwanted appearance of tensile normal stress on brittle materials, also “at rest”, and even some dramatic changes of stress patterns as the die height increases with respect to the rectangular profile dimensions. Different materials behave differently, mainly due to difference of thermal expansion coefficients. Profile changes occur when the dies are heated up to the temperature required for warm compaction. The deformation patterns depend on compaction temperature and on thermal expansion coefficients.

Oxystarch and other Polyaldehydes: The Present Status in the Treatment of Uremia

Polyaldehydes, such as oxidized starch and cellulose, are in theory very potent urea and ammonia binders. However, their clinical use in the last ten years has lit some hope; their efficacy in reducing body uremic waste nitrogen accumulation has suffered, admittedly, comparable enthusiasm. In this short presentation, we wish to give some reasons and focus the possible ways for improving the clinical efficacy of these sorbents.