PubMed Health⌕ Search

Biomedical subjects

C Pisani

Publications and source records attributed to C Pisani.

At least 19 recordsLinked to original sources
PubMed2006

An ab initio periodic study of acidic chabazite as a candidate for dihydrogen storage.

A theoretical B3LYP study, adopting a polarized double-zeta quality Gaussian basis set, was performed to characterize acidic chabazite by using the periodic CRYSTAL03 program. Different Si/Al loadings (1/1, 3/1, 5/1, and 11/1) were considered, and for each of them the most stable aluminum distribution and location of the acidic proton, needed as charge balancer, were identified. With the optimal structures, the energy of formation and the anharmonic O-H stretching frequency were calculated with the latter being in good agreement with the experimental data. The B3LYP optimal position of H2 physisorbed at the acidic Brönsted sites of chabazite (Si/Al = 11/1 and 5/1) brings about an interaction energy definitely smaller than that derived from infrared spectroscopy, because of the known deficiencies of this functional to cope with dispersive interactions. The latter was included by means of an ONIOM-like procedure that combines periodic B3LYP energy with results at the MP2 level on selected clusters cut out of the chabazite framework. Adsorption of two H2 molecules for Si/Al = 5/1 chabazite showed a complete independence of each Brönsted site, and neither through-space nor intrastructure polarization effects are present. Within the periodic B3LYP approach shifts in both O-H and H-H anharmonic frequencies were also computed and compared with unperturbed values and with the available experimental results.

Journal Article↗
PubMed2006

Basal cell carcinoma of the vulva.

Basal cell carcinoma (BCC), the most common human malignancy, accounting for 75% of all non-melanoma skin cancer, is uncommon on unexposed skin such as the perianal and genital regions. We describe a woman with BCC of the vulva treated with local resection. All margins of excision were free of disease. The patient recovered without complication and there have been no recurrences after 2 years of follow-up. Approximately 200 cases of BCC on perianal and genital skin have been reported in the literature. Although the aetiology of vulvar BCC is not known, early diagnosis is important. Because BCC in these sites sometimes seems innocuous, biopsy of all suspect lesions is advisable.

Aged↗
PubMed2005

Experimental and theoretical study of a surface stabilized monolayer phase of nickel oxide on Pd(100).

A surface stabilized monolayer phase of nickel oxide, c(4 x 2)-Ni(3)O(4), has been found to grow epitaxially under reactive deposition conditions on Pd(100), in the presence of other adsorbed phases and in competition with them. High-quality scanning tunneling microscopy data are reported and discussed, including a detailed analysis of the defects and of the border morphology of this new phase. The data are discussed in the light of ab initio simulations of the electronic, energetic, and geometric properties of such a phase. A hybrid-exchange density functional theory approach has been used, and a slab model is adopted where palladium is simulated by a thin film covered on both sides by regular epilayers. A growth model has been developed that explains both the unusual stoichiometry of the phase and the observed defects.

Journal Article↗
PubMed2005

Local-MP2 electron correlation method for nonconducting crystals.

Rigorous methods for the post-HF (HF-Hartree-Fock) determination of correlation corrections for crystalline solids are currently being developed following different strategies. The CRYSTAL program developed in Torino and Daresbury provides accurate HF solutions for periodic systems in a basis set of Gaussian type functions; for insulators, the occupied HF manifold can be represented as an antisymmetrized product of well localized Wannier functions. This makes possible the extension to nonconducting crystals of local correlation linear scaling On techniques as successfully and efficiently implemented in Stuttgart's MOLPRO program. These methods exploit the fact that dynamic electron correlation effects between remote parts of a molecule (manifesting as dispersive interactions in intermolecular perturbation theory) decay as an inverse sixth power of the distance R between these fragments, that is, much more quickly than the Coulomb interactions that are treated already at the HF level. Translational symmetry then permits the crystalline problem to be reduced to one concerning a cluster around the reference zero cell. A periodic local correlation program (CRYSCOR) has been prepared along these lines, limited for the moment to the solution of second-order Moller-Plesset equations. Exploitation of point group symmetry is shown to be more important and useful than in the molecular case. The computational strategy adopted and preliminary results concerning five semiconductors with tetrahedral structure (C, Si, SiC, BN, and BeS) are presented and discussed.

Journal Article↗
PubMed2005

Malignant hypercalcemia in vulvar cancer.

Humoral hypercalcemia of malignancy (HHM) is a common paraneoplastic syndrome, most often associated with squamous cell carcinoma of the lung, esophagus, kidneys and breast, but rarely with vulval cancer. In most patients, HHM is associated with over-production of a peptide analogue of parathormone (parathyroid hormone-related protein, PTHrP). The case of a 70-year-old patient with massive squamous cell epithelioma of the vulva complicated by HHM is reported. To our knowledge, this is the first documented case with high serum concentrations of PTHrP and immunohistochemical confirmation of PTHrP production by neoplastic cells.

Aged↗
PubMed2004

Discoid lupus erythematosus of the vulva.

Genital involvement is a rare manifestation in discoid lupus erythematosus (DLE) and systemic lupus erythematosus (SLE), and there are few reports on vulvar clinical features. We describe a 41-year old Caucasian woman with bilateral vulvar DLE. Although vulvar lesions in lupus are probably more common than is realized, the present report is the first case of genital DLE documented in a female.

Adult↗
PubMed2000

[Pre-eclampsia: role of excessive caloric intake].

OBJECTIVE: To compare the average daily diet of women having physiologic pregnancy versus patients presenting preeclampsia (PE) in order to evaluate if increased caloric intake is associated with preeclampsia. METHODOLOGY: The macronutrients and kilocalories in measurements obtained from diaries filled in over a seven day period by 147 pregnant women (30 preeclamptics, 117 with physiologic pregnancy were compared (the proportion of about 1/4 between the two groups was chosen to increase the statistical efficacy, because this pathology is rather unfrequent). RESULTS: The analysis of the diaries shows that the preeclamptic women consume, every day a greater quantity (p < 0.05) of kilocalories, proteins and lipids than the physiologic pregnancy. No statistically significant difference was found for fibres and carbohydrates (the last ones recorded without distinguish mono and disaccharides from polysaccharides). Physiologic pregnancy mean Body Mass Index is 21.6 versus 26.4 of PE women (p < 0.05). CONCLUSION: Intake of energy, protein and lipid were positively associated with risk of PE. Overweight patients are highly at risk of contracting PE. These data, according to others trials confirm the advisability: 1) to analyse the diet of pregnant women; 2) to reduce nutritional intake, if in excess, first of all, in women at risk of PE; 3) to suggest loosing weight to overweight patients before initiating a pregnancy.

Energy Intake↗
PubMed1997

Preeclampsia: correlation between changes in symptomatology and changes in diet.

This study analyzes 13 cases of pregnant women affected by varying degrees of preeclampsia, and correlates the patients' data (height, weight, preeclampsia symptoms according to intensity and time of onset) to the amount of mean daily intake of nutrients (proteins, lipids, carbohydrates, starch, total calories, Na). The amount of nutrients was obtained processing with a special computer software the patients' weekly dietary diaries. The analysis of the data shows the correlation between the onset of preeclampsia symptomatology and the excess of certain nutrients: excess in calories and/or proteins, and/or lipids, and/or simple sugars, and/or sodium. A reduction in the amount of these nutrients, especially proteins and Na when applied during the early stage of preeclampsia symptoms, favours the disappearance of the clinical signs of the disease.

Adult↗