Fabrication and Characterization of Sensitive Polymer (Nano)Composites

We report on the fabrication process of a polymer sensing device based on a thin film composite obtained by spinning or casting a carbon fillers/thermoplastic polymer dispersion on a glass substrates. In this work we produce thin composite films characterized by different grade of dispersion of carbon black in polymer matrix (Poly(methyl-methacrylate), Poly(2 hydroxy-ethyl-methacrylate) and atactic poly(styrene)). We discuss, in particular the effect of the polymer and filler characteristics on the thin film morphology. Device material response towards different analytes will be also discussed. Size distribution of filler in polymer suspension and deposition method type strongly influence homogeneity and conductivity of corresponding polymer composite films and finally their sensor properties.     

BOLD signal and vessel dynamics: a hierarchical cluster analysis

The aim of the present study was to analyze blood oxygenation level-dependent (BOLD) signal variation during an apnea-based task in order to assess the capability of a functional magnetic resonance imaging (fMRI) procedure to estimate cerebral vascular dynamic effects. We measured BOLD contrast by hierarchical cluster analysis in healthy subjects undergoing an fMRI experiment, in which the task paradigm was one phase of inspirational apnea (IA). By processing the time courses of the fMRI experiment, analysis was performed only on a subclass of all the possible signal patterns; basically, root mean square and absolute variation differences have been calculated. Considering the baseline value obtained by computing the mean value of the initial rest period as reference, particular voxels showed relative important variations during the IA task and during the recovery phase following the IA. We focused our interest on the signal response of voxels that would correspond mainly to white and gray matter regions and that also may be affected by the proximity of large venous vessels. The results are presented as maps of space-temporal distribution of time series variations with two levels of hierarchical clustering among voxels with low to high initial response. Furthermore, we have presented a clustering of the signal response delay, conducting to a partition and identification of specified brain sites.     

Organic film thickness influence on the bias stress instability in?sexithiophene field effect transistors

In this paper, the dynamics of bias stress phenomenon in Sexithiophene (T6) Field Effect Transistors (FETs) has been investigated. T6 FETs have been fabricated by vacuum depositing films with thickness from 10 to 130 nm on Si/SiO₂ substrates. After the T6 film structural analysis by X-ray diffraction and the FET electrical investigation focused on carrier mobility evaluation, bias stress instability parameters have been estimated and discussed in the context of existing models. By increasing the film thickness, a clear correlation between the stress parameters and the structural properties of the organic layer has been highlighted. Conversely, the mobility values as a result are found to be almost thickness independent.     

Metabolic alteration transients during paroxysmal activity in an epileptic patient with fixation-off sensitivity: a case study

The purpose of this study was to investigate short-time metabolic variations related to continuous epileptic activity elicited by fixation-off sensitivity (FOS). Time-resolved magnetic resonance spectroscopy was performed on a patient on whom previous clinical findings clearly indicated presence of FOS. The epileptic focus was localized with a simultaneous electroencephalographic and functional magnetic resonance imaging study. The results showed a linear increase of the sum of glutamate and glutamine with time of paroxysmal activity in epileptic focus and much greater concentration of choline-containing compounds in focus than in the contralateral side.     

Fold length of single crystals of polystyrene: A conflict with crystallization theories at high supercoolings

The purpose of the work was to test existing theories of chain folded polymer crystallization over a supercooling range which is much is excess to what could be hitherto realized. This was made possible by the recognition that crystallization of isotactic polystyrene in solution could be conducted over an exceptionally wide range of temperatures in an isothermally controlled manner. The results revealed that the familiar inverse dependence of the fold length on supercooling (the behavior observed and studied in polyethylene) was only displayed at the lowest supercooling; at high supercoolings the fold length reached a constant lowest value unaffected by further lowering of the crystallization temperature. This is in conflict with present theories, which predict a catastrophic upswing in fold length at high supercoolings. It is demonstrated that the observations cannot be made compatible with this prediction by any conceivable adjustment of the numerical parameters. The implications of these findings are discussed.     

How the NPX data format handles EEG data acquired simultaneously with fMRI

There is a growing interest in combining EEG and (f)MRI data as they provide complementary information: EEG is characterized by a high temporal resolution but poor spatial one, while fMRI is characterized by a high spatial resolution but low temporal one. However, while a standard file format for storing EEG data is available since over a decade, it does not fulfill the needs of modern protocols and devices such as those involved in simultaneous EEG and fMRI recordings. The main reasons are the limited bit resolution, some difficulties encountered in handling and storing acquisition events or trace markers for off-line analyses and the impossibility to add some protocol-specific information that is not considered in the actual data formats. This, among others, hinders the release of free analysis software and makes it difficult to share data across different laboratories as every research unit develops its own tools according to its needs, stores data in proprietary formats and a lot of time is spent building software applications for converting data from one format to another. The NPX (NeuroPhysiological signals in eXtensible Markup Language) data format was defined to overcome these and other limitations, and here its main characteristics are reported as well as how some typical problems occurring in simultaneous EEG-fMRI recordings are also treated. Many tools based on the NPX technology can be freely downloaded, including a tool for removing artifacts occurring during simultaneous EEG-fMRI recordings.     

A dilutional microassay for serum ionized calcium using ion-selective electrodes

A microassay for serum ionized calcium was developed and characterized with commercially available instrumentation that employs conventional electrochemical, ion-selective electrode, methodology. The microassay consists of diluting serum with an appropriate concentration and volume of tris(hydroxymethyl)aminomethane at physiological pH and ionic strength. The diluent was capable of buffering serum throughout the normal and pathologic ranges of pH and the performance characteristics of the microassay were independent of serum protein concentration. An application of the method is provided and the results support the view that calcium may be involved in cysteamine-induced attenuation of episodic growth hormone secretion in male rats.     

Polycondensed nitrogen heterocycles. IX. 5,6-dihydro-7H-pyrrolo[1,2-d][1,4]benzodiazepin-6-one

The reaction of amino derivative I with bromoacetyl bromide led to the formation of a complex mixture from which, in addition to the title compound, which was formed in low yield, compounds III, IV and VI were separated. Pyrrolo[1,2-d][1,4]benzodiazepine V was obtained in 85% yield when the bromoamide III was treated with an equimolar amount of potassium t-butoxide.