Showing papers by "University of Palermo published in 1991"

Effect of silver deposits on the photocatalytic activity of titanium dioxide samples for the dehydrogenation or oxidation of 2-propanol

Abstract: Until now, the effect of the deposition of metal particles onto a powdered semiconductor oxide on its photocatalytic activity has been determined for group VIII transition metals only. In this study, AGTiO2 samples were prepared by photodeposition, characterized by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) and tested, under band-gap illumination, using the oxidation of 2-propanol (neat liquid phase or mixed with water) in the absence or presence of molecular oxygen. The silver deposits were found to be metallic both before and after use, but the size of the particles and their distribution on the support were markedly influenced by the type of TiO2 sample. A small amount of silver caused the catalytic oxygen-free oxidation of 2-propanol, although the rate was much lower than that with platinum which possesses dehydrogenating properties. This effect is thought to be due to the electron-attracting role of the metal particles. For oxidation of 2-propanol by molecular oxygen, an optimum silver content was observed (corresponding to a rate improvement of approximately 50%). This was interpreted to be due to the beneficial effects of silver on the trapping of electrons and/or the reduction of oxygen. At higher than optimum silver contents there was a detrimental increase in the probability of recombination of charges at the numerous silver particles. The optimum was shifted to lower values in the presence of water, which is tentatively explained by competitive hole trapping by 2-propanol, water and silver.

Photocatalytic degradaton of phenol in aqueous polycrystalline TiO2 dispersions: the influence of Fe3+, Fe2+ and Ag+ on the reaction rate

Abstract: The influence of Fe3+, Fe2+ and Ag+ on phenol photodegradation performed in aqueous polycrystalline TiO2 (anatase) and TiO2 (rutile) dispersions was investigated. These ions can react very easily with peroxo species produced on the catalyst surface and/or in the solution. Experimental conditions for the continuous photoproduction of Fenton reactive can be achieved in this way. Maximum photoactivity was observed for TiO2 (anatase) in the presence of oxygen and [Fe3+] = 5 × 10−4 M. The behaviour of Fe2+ was similar to Fe3+ for the same experimental conditions. Anatase photoactivity was beneficially influenced in the presence of oxygen and [Ag+] = 1 × 10−4 M.

A case-control study of amyotrophic lateral sclerosis.

Abstract: A retrospective case-control study was conducted using 46 patients affected by amyotrophic lateral sclerosis and 92 closely matched healthy controls. Cases were ascertained through typical clinical and instrumental findings. Putative risk factors (bone fractures or major trauma, exposure to domestic animals, surgical operations, disease among first degree relatives and others) were investigated anamnestically using a standard questionnaire. Using Mantel-Haenzsel estimates of the odds ratio, no association was found between amyotrophic lateral sclerosis and the investigated variables.

Discovery of ten millisecond pulsars in the globular cluster 47 Tucanae

Abstract: IN the past four years a total of 13 millisecond pulsars have been found in 12 different globular clusters. These pulsars are believed to be old neutron stars that have been spun up ('recycled') in low-mass X-ray binary systems1 although some may have been formed by the accretion-induced collapse of white dwarfs in binaries2. The globular cluster 47 Tucanae has an especially dense core, and is therefore a likely site for millisecond pulsar formation. Using the Parkes radiotelescope, we have now detected ten addi-tional millisecond pulsars in 47 Tuc, more than half of which are members of binary systems. Almost half of the known millisecond pulsars and more than a quarter of the known binary pulsars now reside in this one cluster.

Isoerosivity and erosion risk map for Sicily

Abstract: This paper reviews simplified methods for evaluating the rainfall erosivity index and proposes two relationships for estimating the annual value of Wischmeier's rainfall erosivity index at sites equipped with recording and non-recording raingauges. For the Sicilian region, the FAO index was also found to represent the erosion risk. A regional relationship to estimate the standard deviation of the annual erosivity index is proposed. The isoerosivity map is plotted by using 41 values of the rainfall erosivity index calculated by Wischmeier's procedure and 128 values estimated according to a relationship proposed by the authors. Finally, for each of 169 sites, an erosion risk index is calculated and an erosion risk map is plotted.

Severe infantile colic and food intolerance: a long-term prospective study.

Abstract: To determine the relationship between infantile colic and cow's milk protein intolerance (CMPI) in formula-fed infants, 70 infants (38 male, 32 female) were selected, with mean age 30.2 +/- 21.4 days, with severe colic (duration of crying greater than 4 h per day for 5 days per week). In 50 of the infants in the study group (71.4%) there was a remission of symptoms when cow's milk protein (CMP) was eliminated from the diet. Two successive challenges caused the return of symptoms in all these 50 infants. There was a positive anamnesis for atopy in 9 of 50 of the patients with CMP-related colic and in 1 of 20 of those with non-CMP-related colic (p greater than 0.05). A follow-up period of 18 months' mean duration showed that 22 of 50 (44%) of the infants with CMP-related colic and 1 of 20 (5%) of those with non-CMP-related colic developed an overt alimentary intolerance (p less than 0.02). We conclude that a considerable percentage of the infants with severe colic also have CMPI and that in these cases, dietetic treatment should be the first therapeutic approach.

Pliocene-lower Pleistocene chronostratigraphy: A re-evaluation of Mediterranean type sections

Abstract: The Pliocene-Pleistocene stages defined for the Mediterranean region are generally used as the standard chronostratigraphic units for the upper Neogene and Quaternary. The recently developed calcareous plankton bio-chronology based on results from Ocean Drilling Program Leg 107 and numerous outcrop sections provides the necessary time control for evaluating the ages and stratigraphic relationships for the various Pliocene-Pleistocene stages and their associated stratotypes. Our results indicate that the currently accepted stratotypes do not provide a continuous stratigraphic representation for all of Pliocene-early Pleistocene time. On the basis of these findings, we propose a revised chronostratigraphic scheme for this time period. A tripartite subdivision is proposed for the Pliocene Series. The Zanclean Stage is retained for the lower Pliocene, representing the interval from the Miocene/Pliocene boundary (ca. 4.93 Ma) to ca. 3.5 Ma. The middle Pliocene is represented by the Piacenzian Stage, and it incorporates strata deposited from ca. 3.5 to 2.5 Ma. None of the currently used Pliocene stages fully represents the upper Pliocene (ca. 2.5 to 1.6 Ma). As a result, late Pliocene time lacks an adequately defined chronostratigraphic unit. The Selinuntian Stage appears to be the most appropriate stage for the lower Pleistocene (ca. 1.6 to 0.8 Ma). It can be divided into three stratigraphically continuous substages (Santernian, Emilian, and Sicilian). The Calabrian Stage, which is commonly used to designate the lowest part of the Pleistocene, should be abandoned because its stratotype does not include a record of the first 500,000 yr of Pleistocene time.

Exocrine pancreatic function in children with coeliac disease before and after a gluten free diet.

Abstract: This study was designed to determine the extent of pancreatic insufficiency in untreated coeliac disease and whether pancreatic secretion is impaired after a prolonged gluten free period. Three groups of patients were studied: group A comprised 44 patients, mean (SD) age 4.0 (3.1) years, with coeliac disease and total or subtotal atrophy of the intestinal mucosa; group B comprised 67 patients, mean age 4.4 (3.0) years, with coeliac disease but with normal morphology of the intestinal villi (after 12.9 months of a gluten free diet); group C comprised 49 control subjects, mean age 3.2 (3.0) years, with normal jejunal histology. In all subjects exocrine pancreatic function was determined by the secretin-caerulein test; bicarbonate concentration and lipase, phospholipase, and chymotrypsin activity were measured after an intravenous injection of secretin 1 clinical unit (CU) + caerulein 75 ng/kg body weight. Faecal chymotrypsin concentration was also assayed. No significant difference was found between values of the duodenal output of pancreatic enzymes and bicarbonate obtained in the three groups; however, 10 of 44 untreated coeliac patients showed tryptic or lipolytic activity, or both, below the normal limit for our laboratory. The mean value of the faecal chymotrypsin concentration was significantly lower in untreated than in treated coeliac patients (p less than 0.0001) or in control subjects (p less than 0.0001). It is concluded that untreated coeliac patients may have pancreatic deficiency independent of a decrease in enterohormone release. No primary or secondary pancreatic insufficiency was found in coeliac patients where the intestinal mucosa had returned to normal.

Effect of obesity on left ventricular function studied by radionuclide angiocardiography.

Abstract: Several studies have shown a significant association of obesity with cardiovascular morbidity and mortality. The present study was carried out to investigate central and systemic haemodynamics in overweight and moderate obese, but otherwise healthy subjects, and in a lean control group to determine whether obesity can influence left ventricular performance per se. In this study an attempt has been made to eliminate misleading factors, such as diabetes, lipid abnormalities and hypertension. A total of 67 subjects, 44 with overweight or moderate obesity and 23 lean healthy subjects, were included. Patients were divided into three groups according to BMI levels and Garrow's criteria as follows: lean control group (BMI 30 98 months). Haemodynamic assessment was performed using first pass radionuclide angiocardiography. When compared with lean subjects, overweight and moderate obese subjects were characterized by a significant increase in cardiac output (CO), stroke volume (SV), end diastolic volume (EDV), end systolic volume (ESV), total blood volume (TBV) and total plasma volume (TPV) and by a significant decrease in left ventricular ejection fraction (EF); some of these changes appeared to be related to the degree of obesity. In overweight and moderate obese subjects, total peripheral resistance (TPR) was lower than in lean controls, but this difference was not significant. Moreover EF values were significantly lower in subgroup B in comparison with subgroup A, but only in moderate obese subjects (P < 0.01). In all the subjects studied, BMI was inversely correlated with EF (P < 0.001) and directly with CO (P < 0.01) and with TBV (P < 0.01). In all the obese subjects, EF was inversely correlated with DO (P < 0.01). Multiple regression analysis showed that correlations between EF, BMI and DO were independent of mean blood pressure values. In conclusion, the results support the suggestion that obesity could represent an independent risk factor for congestive heart failure after a long term incubation period.

Rifaximine versus neomycin in the treatment of portosystemic encephalopathy.

Abstract: In 14 patients with cirrhosis and chronic portosystemic encephalopathy, the effectiveness of treatment with a new non-assorbable antibiotic (rifaximine) was compared to neomycin. The parameters evaluated were: bradylalia, flapping tremor, performance, visual evoked potentials and the trial making test. Both treatments were combined with lactulose. The analysis of results showed a rate of positive results in the patients treated with rifaximine greater than that with neomycin. Differences, however, were not significant.

Door-to-Door Prevalence Survey of Neurological Diseases in a Sicilian Population

Abstract: In three municipalities of Sicily, a prevalence survey of major neurological diseases was conducted door-to-door using screening and examination to find cases. This was the first large-scale neuroepid

Electron-pion discrimination with a scintillating fiber calorimeter

Abstract: We report on an experimental study of a variety of techniques for discriminating between (isolated) electrons and pions in a lead and scintillating fiber calorimeter without longitudinal segmentation. Using information from the lateral shower development, from a pre-shower detector, from the time structure of the signals, or from a combination of these we measure pion rejection factors of up to several thousand while maintaining electron efficiencies of 95% or higher.

Mass spectrometric identification of the amino donor and acceptor sites in a transglutaminase protein substrate secreted from rat seminal vesicles.

Abstract: Four different transglutaminase-modified forms of a protein secreted by the rat seminal vesicles (SV-IV) were synthesized in vitro and characterized. FAB maps of both the native protein and its derivatives, produced by the purified guinea pig liver enzyme in the presence or absence of the polyamine spermidine, were obtained by mass spectrometric analysis after proteolytic digestions. Two differently derivatized SV-IV molecular forms, both possessing only one glutamine residue out of two (Gln-86) cross-linked to endogenous lysine residues, were produced when spermidine was omitted from the reaction mixture: (i) an insoluble homopolymer in which Lys-2, -4, -59, -78, -79, and -80 were involved in the linkage; (ii) a soluble form of the protein with an intramolecular epsilon-(gamma-glutamyl)lysine isopeptide bond between Gln-86 and Lys-59. Two species of SV-IV-spermidine adducts were obtained when the protein was treated with transglutaminase in the presence of high concentrations of the polyamine. The first one was characterized by one spermidine molecule covalently bound to Gln-86 and the second one by two spermidine molecules respectively bound to Gln-9 and Gln-86.

Photon absorption by aqueous TiO2 dispersion contained in a stirred photoreactor

Abstract: We present a simple experimental method which allows the evaluation of the absorbed photon flow. The method is based on measurements of transmitted photon rates (by means of standard actinometer solutions) for different reactor thicknesses and/or catalyst concentrations. The method was applied to phenol degradation reaction carried out in a stirred batch phtotoreactor containing aqueous TiO 2 (anatase) dispersion, directly irradied by a 1,500 W Xe lamp

A comparison of spreading and motility behaviour of 8701-BC breast carcinoma cells on type I, I-trimer and type V collagen substrata. Evidence for a permissive effect of type I-trimer collagen on cell locomotion.

Abstract: Ductal infiltrating carcinoma (d.i.c.) of human breast is a highly invasive neoplasm characterized by enhanced deposition of collagen. Paradoxically, enhanced collagen deposition is not correlated with inhibition of the migration of tumour cells into the host tissue. d.i.c. is characterized by the reappearance of ‘embryonic’ type I-trimer collagen and an increase in type V collagen content in the matrix. The effects of these two collagen types were compared with type I collagen as culture substrata on the spreading pattern, cytoskeletal organization and motile behaviour of 8701-BC breast carcinoma cells using rhodamine-phalloidin staining, a DNAase I-competition assay, scanning electron microscopy and time-lapse video-microscopy. Cells grown on type I collagen were stationary, showing a well-spread morphology and an extensive stress fibre pattern. Cells grown on type V collagen were also stationary, but displayed a poorly spread and elongated morphology. In contrast, cells grown on trimer collagen were motile and displayed a compact morphology and a reduced content of stress fibres. Both single-cell and group motility were detectable on trimer collagen substratum. These data are consistent with the existence of two opposite local signals, type I-trimer and type V collagens, which may confer a more or a less metastatic phenotype on breast carcinoma cells. Moreover, the synthesis of trimer collagen in d.i.c. is conceivably instrumental in providing new stromal pathways permitting tumour cells to infiltrate the host tissue.

Hydrophilic and Hydrophobic Polymeric Derivatives of Anti-Inflammatory Agents Such as Alclofenac, Ketoprofen, and Ibuprofen:

Abstract: Macromolecular prodrugs of a hydrophilic polymer [α,β-poly( N- hydroxyethyl)-DL-aspartamide (PHEA)] was used as a drug carrier. Three poly- (HEA)-NSAID adducts were studied: poly(HEA)-Alclofenac, p...