The influence hydrogen atom addition has on charge switching during motion of the metal atom in endohedral Ca@C60H4 isomers.

Density functional theory has been applied in a study of charge transfer between an endohedral calcium atom and the fullerene cage in Ca@C60H4 and [Ca@C60H4](+) isomers. Previous calculations on Ca@C60 have shown that the motion of calcium within a fullerene is accompanied by large changes in electron density on the carbon cage. Based on this observation, it has been proposed that a tethered endohedral fullerene might form the bases of a nanoswitch. Through the addition of hydrogen atoms to one hemisphere of the cage it is shown that, when compared with Ca@C60, asymmetric and significantly reduced energy barriers can be generated with respect to motion of the calcium atom. It is proposed that hydrogen atom addition to a fullerene might offer a route for creating a bi-stable nanoswitch that can be fine-tuned through the selection of an appropriate isomer and number of atoms attached to the cage of an endohedral fullerene.This article is part of the themed issue 'Fullerenes: past, present and future, celebrating the 30th anniversary of Buckminster Fullerene'.

Polarisation charge switching through the motion of metal atoms trapped in fullerene cages.

The formation of an endohedral fullerene can lead to charge transfer and the generation of a trapped positively charged metal ion. Using Ca@C60 and [Ca@C60](+) endohedral fullerenes as models, density functional theory calculations predict that the motion of a calcium ion within a fullerene is accompanied by large changes in electron density on the surrounding carbon cage. In the case of [Ca@C60](+), partial atomic charge distribution on the carbon cage is split between hemispheres into regions of positive and negative charge as Ca(n+) moves inside the fullerene cage (non-integer n strongly depends on position of the ion). It is proposed that within tethered fullerene cages the movement of partial atomic charge could form the bases of a molecular polarisation storage bit, and that adopted in the form of [Ca@C60](+) the presence of an overall charge may offer a route to either optical or electronic control.

Relativistic DFT calculations of magnetic moments of pristine and thiolated Mn@Aux (x = 6, 12).

In this work we present the results of relativistic DFT calculations of magnetic moments for manganese inserted into a gold ring (Mn@Au6) or a cage-like structure (Mn@Au12) both pristine and n-thiolated. Optimization has been carried out to obtain different isomers always favouring the endohedral gold clusters with Mn inside. For the total magnetic moment (from electronic population analysis) verification of the jellium model has been performed in each case. It is concluded that the magnetic moments arise largely from the doped manganese atom and that thiolation can modulate its value, which is not present in the pure form. In the Mn@Au12 clusters we observed the formation of a hole in their structure; this could be a characteristic of insertion of a highly ferromagnetic dopant in some metal clusters, such as gold, and this could act as a precursor of the formation of gold magnetic nanotubes.

Experimental binding energies for the metal complexes [Mg(NH3)n]2+, [Ca(NH3)n]2+, and [Sr(NH3)n]2+ for n = 4-20 determined from kinetic energy release measurements.

A supersonic source of clusters has been used to prepare neutral complexes of ammonia in association with a metal atom. From these complexes the following metal-containing dications have been generated: [Mg(NH3)n](2+), [Ca(NH3)n](2+), and [Sr(NH3)n](2+), and for n in the range 4-20, kinetic energy release measurements following the evaporation of a single molecule have been undertaken using a high resolution mass spectrometer. Using finite heat bath theory, these data have been transformed into binding energies for individual ammonia molecules attached to each of the three cluster systems. In the larger complexes (n > 6) the results exhibit a consistent trend, whereby the experimental binding energy data for all three metal ions are very similar, suggesting that the magnitude of the charge rather than charge density influences the strength of the interaction. From a comparison with data recorded previously for (NH3)nH(+) it is found that the 2+ charge on a metal ion has an effect on the binding energy of molecules in complexes containing up to 20 solvent molecules. Although subject to comparatively large experimental errors, the results recorded for Ca(2+) and Sr(2+) when n ≤ 6 show evidence for the formation of an inner solvation shell containing up to 6 molecules. However, Mg(2+) exhibits relatively low binding energies when n = 5 and 6, which suggests that a second shell starts to form before there are 6 ammonia molecules bound to the metal ion. This conclusion is supported by DFT calculations and it is proposed that these complexes could take the form [Mg(NH3)4(NH3)](2+) when n = 5 and either [Mg(NH3)4(NH3)2](2+) or [Mg(NH3)5(NH3)](2+) when n = 6. In each case, additional molecules are hydrogen bonded to one or more molecules in the inner solvation shell.

Special care units for demented patients: a multicenter study.

The local government of Regione Lombardia, Italy, recently (1994) funded a clinical and research project specifically devoted to dementia (Piano Alzheimer). A central role in this project has been reserved for the special care units (SCUs) for demented patients with behavioral disturbances. In order to evaluate their effectiveness, eight SCUs took part in this study. A specifically designed care program, focusing on environment and staff, was implemented in each SCU. Cognitive, functional, and somatic health status, and use of psychotropic drugs and of physical restraints were assessed at baseline, and after 3 and 6 months in 55 consecutively admitted patients. The data show an overall reduction in behavioral disturbances and a decreased use of psychotropic drugs and physical restraints.

[The psychological characteristics of dyspepsia. A controlled study with gastroscopic follow-up]. / Caratteristiche psicologiche della dispepsia. Studio controllato con follow-up gastroscopico.

It's known that some psychologic factors could be implicated in dyspepsia. Therefore, the psychologic aspects of 38 dyspeptic patients (17 males, 21 females, aged 18-65 years), who underwent digestive endoscopy, were evaluated by means of Rorschach and MMPI test. Patients with previous peptic ulcer history, with chronic ethanol or NSAID intake, operated on digestive tract and patients with behavioural problems were excluded. The results of psychological tests enhanced two main groups: anxiety patterns (17 patients--49%) and normal patterns (21 patients--55%). Endoscopic and histological findings moreover showed: "anxious" group--12 patients with chronic gastritis (HP+ 50%), 5 patients with normal endoscopy; "normal" group--16 patients with chronic gastritis (HP+ 87.5%), 5 patients with normal endoscopy. This study suggests that in about 50% of dyspeptic patients anxious pattern is present. Moreover chronic gastritis is more frequently associated to Helicobacter pylori in non-anxious patients.

[The effect of colloidal bismuth and its combination with amoxicillin on the elimination of Helicobacter pylori in patients with a duodenal ulcer and chronic antral gastritis]. / Effetto del bismuto colloidale e dell'associazione con amoxicillina sull'eradicazione dell'Helicobacter pylori in pazienti con ulcera duodenale e gastrite cronica antrale.

Although the aetiopathogenetic role of Helicobacter Pylori (HP) in duodenal ulcer and in chronic gastritis seems now well defined, we have not yet standardized therapeutic schedules to achieve disappearance of HP. This study was aimed at evaluating the efficacy of two different therapeutic schedules, colloidal bismuth alone [CB(1200 mg/day)], vs. association with amoxicillin [CB+A(3 g/day)] for six weeks, to clear HP from antral specimens in a cohort of dyspeptic patients. 49 consecutive patients (23 females, 26 males, mean age 47 years, range 22-69) with HP in gastric specimens, 30 suffering from chronic antral gastritis (CG) and 19 affected by duodenal ulcer (DU) were treated with CB (37 pts) or with CB+A (12 pts). DU patients were given also H2-blockers. These latter patients were all healed at the endoscopic control performed after therapy. 4 out of 13 DU patients (31%) treated with CB were found HP free. In 4 out of 6 DU patients (66%) treated with CB+A, HP was no more detectable. As for CG patients, 12 out of 24 (50%) were free from HP at control when treated with CB, while only 2 out of 6 (33%) when CB+A was administered. This study suggests that colloidal bismuth is more effective when administered associated with amoxicillin, but this concerns only DU patients. No relation between endoscopic healing of UD and HP presence was found.