Pressure-induced mesoscopic disorder in protic ionic liquids: first computational study

The application of high pressure to protic ionic liquids with short alkyl chains induces a progressive homogenization of the structure.

Organization and evolution of parieto-frontal processing streams in macaque monkeys and humans

The functional organization of the parieto-frontal system is crucial for understanding cognitive-motor behavior and provides the basis for interpreting the consequences of parietal lesions in humans from a neurobiological perspective. The parieto-frontal connectivity defines some main information streams that, rather than being devoted to restricted functions, underlie a rich behavioral repertoire. Surprisingly, from macaque to humans, evolution has added only a few, new functional streams, increasing however their complexity and encoding power. In fact, the characterization of the conduction times of parietal and frontal areas to different target structures has recently opened a new window on cortical dynamics, suggesting that evolution has amplified the probability of dynamic interactions between the nodes of the network, thanks to communication patterns based on temporally-dispersed conduction delays. This might allow the representation of sensory-motor signals within multiple neural assemblies and reference frames, as to optimize sensory-motor remapping within an action space characterized by different and more complex demands across evolution.

Hydration Phenomena in a Concentrated Aqueous Solution of Ce(NO3)3. X-ray Diffraction and Raman Spectroscopy

The scattering of X-rays from a concentrated Ce(NO3)3 aqueous solution has been measured and analyzed. The experimental correlation function appears to be mainly characterized by the hydration of the cation: peaks at about 2.55 and 4.65 Å. Good agreement with experimental data is achieved through a model in which the Ce(III) ions have a first and a second hydration shell and also the nitrate group is considered hydrated. Complex formation between cation and anion is confirmed by using Raman spectroscopy.

X-Ray Diffraction Study on Hydration and Ion-Pairing in Aqueous ZnSO4 Solution

An X-ray diffraction experiment on a 2.98 molar ZnSO4 aqueous solution has been interpreted in terms of coordination models. The best agreement between model and experimental structure functions was reached when the Zn2+ ion is hydrated in octahedral form, with twelve water molecules in a second hydration shell, bonded by shortened H-bonds to the first hydration shell. The sulfate group is loosely coordinated by 8.2 water molecules. Besides the dominating Zn(H2O)2+ 6 complexes, about 40% [Zn(H2O)5SO4] inner complexes were found to be consistent with the X-ray data. Alternative models of cationic hydration are critically examined and for the sulfate group the independent atom approximation is compared with a spherical molecular description.

An X-ray and NMR Study on Cerium(III) and Magnesium(II) Perchlorate Solutions

Metal-perchlorate solutions have been investigated by the X-ray scattering technique and 35Cl NMR spectroscopy. The aim of this work was to obtain structural information on the complex formation between the Cerium and the Perchlorate group and on the ClO- 4 - H2O interactions. The NMR data, the correlation functions and the analysis of the structure functions agree with the literature information about the Ce - (OClO3)z species present in aqueous solutions. Good agreement with experimental data is achieved through a model in which the Perchlorate ions are bonded as monodentate ligands to the Cerium(III). No complex formation is confirmed for Mg(II). The cations also possess a second coordination shell of water molecules. Some indications have been obtained supporting the presence of ClO- 4 - H2O contacts.

A Comparative X-Ray Diffraction Study of Aqueous MnSO4 and Crystals of MnSO4·5H2O

X-ray single crystal analysis of MnSO4·5H2O shows that the manganese atoms are octahedrally coordinated by oxygen atoms, four of which belong to water molecules and two to sulphate groups.

A model derived from the crystal structure was fitted to the X-ray scattering intensities from aqueous MnSO4. Good agreement with experimental data is achieved using a model in which Mn(H2O)6-z(OSO3)z +2-2z interacts with about ten water molecules and each sulphate ion with about seven water molecules.

On the Structure in Aqueous Superconcentrated Calcium Nitrate

Liquid hydrous calcium nitrate of composition Ca(NO3)2 · 3.5 H2O was investigated by X-ray diffraction. Experimental data were interpreted in terms of geometrical models suggested by the structure of the crystalline hydrates Ca (NO3)2 · 3H2O and Ca(NO3)2 · 4H2O, in which calcium ions are coordinated to nine oxygen atoms, partly coming from water molecules, partly from NO3 -ions.

X-Ray Diffraction and Structural Properties of Aqueous Solutions of Divalent Metal-Chlorides

X-ray diffraction data are reported for aqueous solutions of CaCl2 (6.30 M), CdCl2 (0.87 and 1.26 M) and NiCl2 (1.96 and 3.88 M). The highly concentrated CaCl2 solution shows a medium range order resembling that of the corresponding hydrate crystal. The CdCl2 solutions are characterized by the presence of complexes with chloride ions in the first coordination sphere of the cation. In NiCl2 solutions, a first sphere Ni-Cl coordination can be excluded and the existence of six Ni-H2O nearest neighbour contacts is clearly confirmed. In these solutions no evidence was found for the existence of highly ordered structures; hexa-aquo cations interact with external water molecules and, at the highest concentration, some outer sphere Ni-Cl correlation is possible as due to packing.

Amino acid anions in organic ionic compounds. An ab initio study of selected ion pairs

The combination of amino acids in their deprotonated and thus anionic form with a choline cation gives origin to a new and potentially important class of organic ionic compounds. A series of such neutral ion pairs has been investigated by first principle methods. The results reveal intriguing structural motives as well as regular patterns in the charge distribution and predict a number of vibrational and optical properties that could guide the experimental investigation of these compounds. The replacement of choline with its phosphocholine analogue causes the spontaneous reciprocal neutralization of cations and anions, taking place through the transfer of a proton between the two ions. Systems of this kind, therefore, provide a wide and easily accessible playground to probe the ionic/polar transition in organic systems, while the easy transfer of H(+) among neutral and ionic species points to their potential application as proton conductors. The analysis of the ab initio data highlights similarities as well as discrepancies from the rigid-ions force-field picture and suggests directions for the improvement of empirical models.

The diameter of cortical axons depends both on the area of origin and target

In primates, different cortical areas send axons of different diameters into comparable tracts, notably the corpus callosum (Tomasi S, Caminiti R, Innocenti GM. 2012. Areal differences in diameter and length of corticofugal projections. Cereb Cortex. 22:1463-1472). We now explored if an area also sends axons of different diameters to different targets. We find that the parietal area PEc sends thicker axons to area 4 and 6, and thinner ones to the cingulate region (area 24). Areas 4 and 9, each sends axons of different diameters to the nucleus caudatus, to different levels of the internal capsule, and to the thalamus. The internal capsule receives the thickest axon, followed by thalamus and nucleus caudatus. The 2 areas (4 and 9) differ in the diameter and length of axons to corresponding targets. We calculated how diameter determines conduction velocity of the axons and together with pathway length determines transmission delays between different brain sites. We propose that projections from and within the cerebral cortex consist of a complex system of lines of communication with different geometrical and time computing properties.

Impairment of online control of hand and eye movements in a monkey model of optic ataxia

The parietal mechanisms for online control of hand trajectory were studied by combining single-cell recording and reversible inactivation of superior parietal area 5 (PE/PEc; SPL) of monkeys while these made reaches and saccades to visual targets, when the target position changed unexpectedly. Neural activity was modulated by hand position, speed, and movement direction, and by pre- and/or postsaccadic signals. After bilateral muscimol injection, an increase in the hand reaction- and movement-time toward both the first and second targets was observed. This caused an increase in the time necessary for the trajectory correction, and therefore an elongation of the hand-path toward the first target location. Furthermore, hand trajectories were different in shape than control ones. An elongation of the eye reaction time to both first and second targets was also observed, which could partially explain the deficit of planning and correction of hand movement. These results identify the superior parietal lobule as a crucial node in the online control of hand and eye movement and highlight the role of the eye impairment in the emergence of the reaching disorder so far regarded as the hallmark of optic ataxia.

Areal differences in diameter and length of corticofugal projections

Cortical areas differ in the size and distribution of neuronal cell bodies, density, and distribution of myelinated axons, connections, and functional properties. We find that they also differ in the diameter of long corticofugal axons, with the thickest axons originating from primary motor, somatosensory, and visual areas and the thinnest ones from prefrontal and temporal areas. Since diameter is proportional to axonal conduction velocity, it can be inferred that action potentials issued from the different areas will be relayed to their targets at different speed. Conduction delays also depend on conduction distance. By computing conduction velocity and conduction distances, we found the longest conduction delays for the primary visual and temporal areas and the shortest for the premotor, primary motor, and somatosensory areas, compatible with the available electrophysiological data. These findings seem to establish a new principle in cortical organization relevant to the pathophysiology of neurological or psychiatric illnesses as well as to the speed of information processing in cortical circuits.

Pseudoaneurysm of the hepatic artery and hemobilia: a rare complication of laparoscopic cholecystectomy; clinical case and literature review

Laparoscopic cholecystectomy is the Gold Standard for the treatment of symptomatic cholelithiasis. There is still an increase in the rate of incidence of biliary and vascular injuries with laparoscopy. Hepatic artery pseudoaneurysm is a rare but serious complication associated with laparoscopic cholecystectomy and bile duct injury. The diagnosis may be difficult. Our experience of a case of iatrogenic lesion of the right hepatic artery with the formation of pseudoaneurysm treated by means of embolization of the artery is presented here.

The structure of geminal imidazolium bis(trifluoromethylsulfonyl)amide ionic liquids: a theoretical study of the gas phase ionic complexes

In this work we report molecular mechanics and ab initio calculations on the geminal di-imidazolium bis(trifluoromethylsulfonyl)amide ionic liquid in the gas phase. We report the likely energetically preferred geometries of the ionic complex and its main features in terms of charge distribution, electronic density, structure, and energetics. We find that the gas phase structure of the ionic complex is quite compact and that the alkyl chain connecting the two imidazolium charged rings is strongly bent in order to maximize their electrostatic interactions with the two anions.

[Intestinal perforation by ingested foreign bodies in the digestive tract: an insidious pathology always of interest. Our experience]

The authors want to present five cases (from May 1999 to May 2009) of acute abdomen from perforation of the foreign body introduced with food. They highlight how the accidental ingestion is very common but the perforation is rare. The preoperative diagnosis, in these cases, is always very difficult and the radiological examinations are not always able to resolve the diagnostic doubt with other acute intestinal diseases that are responsible of perforation. Then, the surgery procedure is, necessarily, the only possible diagnostic and therapeutic means. The mortality and the morbidity remain still high first of all for the delay in the diagnosis and the advanced age of patients.