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Biomedical subjects

L Belloni

Publications and source records attributed to L Belloni.

At least 19 recordsLinked to original sources
PubMed2000

Eccentric poisson-boltzmann cell model

We solve the nonlinear Poisson-Boltzmann equation around a charged colloidal sphere in an electrolyte that is confined in a cell. The colloid has an eccentric position inside the confining sphere. This models the situation in a highly concentrated charge-stabilized colloidal suspension, where a single colloid simultaneously interacts with the whole cage of neighboring colloids. We calculate the ion density profiles, the free energy, and the osmotic pressure as a function of the shifting position. We express the total force acting on the particle as a sum of pair contributions and compare the resulting pair interaction potential law with the standard Derjaguin-Landau-Verwey-Overbeck expression.

Journal Article↗
PubMed1997

Stability of a Nanometric Zirconia Colloidal Dispersion under Compression: Effect of Surface Complexation by Acetylacetone

The stability of a colloidal dispersion of nanometric zirconia particles has been studied during a compression process. Using the osmotic stress method, cycles of compression and reswelling were applied to the dispersion to test the reversibility of the process. Original dispersions are stable in a very limited pH range (0.5-2). At pH 3, the bare particles aggregate irreversibly under compression as checked by osmotic pressure and light and X-ray scattering measurements. To improve the stability, small organic complexing molecules (acetylacetone) were added to the original dispersion. The adsorbed monolayer on the particle surfaces acts as a steric barrier and prevents the two colloids from contacting. As a consequence, the dispersion becomes more compressible and the compression cycle is totally reversible. The experimental data are quantitatively reproduced with a classical theory of statistical mechanics of liquids based on a DLVO-like colloid-colloid potential.

Journal Article↗
PubMed1995

[Listeria monocytogenes meningitis. Description of a clinically significant case].

Meningitis caused by Listeria monocytogenes is a rare affection: it develops from close contagion as professional illness (veterinarians, butchers) or in newborns by infected mothers; in indirect way for ingestion of contaminated food in subjects at high risk: elderly, immunosuppressed patients, alcoholics, diabetics. Clinically it is not diversified from the other bacterial meningitises. In this paper we present a case of Listeria monocytogenes meningitis in an adult female, without a sure occasion of infection and in absence of the factors of typical risk.

Adult↗
PubMed1992

[Gallbladder calculi: what therapy of choice?].

The Authors have analyzed all different methods for the treatment of gallbladder stones which are performed today: the non invasive treatment of the gallstones (oral dissolution therapy and the extracorporeal shockwave lithotripsy), the minimally invasive procedures (contact dissolution therapy and the cholecystolithotomy) and at the end the new surgical techniques (the "minicholecystectomy" and the laparoscopic cholecystectomy). From this study and their experience, based upon 1346 standard cholecystectomy, the Authors have reached the following conclusions: 1) the cholecystectomy remains the only definitive therapy for the gallbladder stones and it is the gold standard to which must be compared the other alternative therapies; 2) the laparoscopic cholecystectomy, even though introduced recently, would become the only method used for cholecystectomy.

Adolescent↗
PubMed1989

Counterion diffusion in heparin solutions.

The physiological importance of heparin is due to its strong interaction with bivalent counterions, especially Ca2+. A diffusional approach of this property is presented in this article: the observable is the self-diffusion coefficient of the counterions, as a function of the ratio of the polyelectrolyte over the added salt concentrations. All the results are in agreement with a simple "quasi-chemical model" in which two different states are assumed for the counterions: "free" or "bound." The proportions of these two types of ions are calculated according to the distribution function of the counterions around the polyion. We assume that those of counterions located at a distance closer than a, the characteristic distance, are bound; the others are free. The ionic distribution function is evaluated by a numerical integration of a cell model Poisson-Boltzmann equation. Finally, this model leads to a very good agreement with the experimental results, if the radius of heparin polyion is assumed to be 6 and 10 A.

Diffusion↗
PubMed1989

[Risk factors and sensitivity to certain antibiotics in hospital urinary infections].

Urinary infections contracted in hospital are one of the most important health problems. The present paper looks at 549 hospitalised patients and 548 subjects referred to the laboratory for routine tests over a period of 6 months. The results showed a higher number of hospital infections in the Medicine Department and this number was directly proportional to certain risk factors such as the presence of a catheter at home, the greater age of patients and a poorer physical condition. The strains most frequently isolated were E. coli and Pseudomonas spp although percentages were different between out-patients and hospitalised patients. The infections in question might be reduced and, at least partially, controlled by means of stricter hygiene on the part of personnel and by a moderate use of vesical catheterism.

Adolescent↗
PubMed1985

[Not Available].

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Digestive System↗