Thermal evolution of MnxOy nanofibres as catalysts for the oxygen reduction reaction.

Manganese oxides (MnxOy) are considered as a promising catalyst alternative to platinum in fuel cell applications. In fact, a proper catalyst is needed in order to facilitate the oxygen reduction reaction (ORR) at the cathode, and platinum is considered the best material due to its low overpotential for this reaction. Contrary to platinum, MnxOy is inexpensive, environmentally friendly and can be shaped into several nanostructures; furthermore, most of them show significant electro-catalytic performance. Several strategies have been carried out in order to increase their efficiency, by preparing light and high-surface area materials. In this framework, nanofibres are among the most promising nanostructures that can be used for this purpose. In this work, a study of the thermal, morphological and catalytic behavior of MnxOy nanofibres obtained through the electrospinning technique is proposed. Emphasis is given to the thermal evolution of the precursors, proposing a possible crystallization mechanism of the different manganese oxides obtained. It turns out that manganese oxide nanofibres exhibit good catalytic performance for the ORR, comparable to those obtained by using Pt-based catalysts.

Environmental electroactive consortia as reusable biosensing element for freshwater toxicity monitoring.

The development of tools to monitor water quality is mandatory in a scenario where clean water resources are decreasing. Here, the biosensing capability of an electroactive river sediment consortium was tested towards three model contaminants (glutaraldehyde, nickel(II) and chromium(III)). The proposed biosensor is a small membrane-less single chamber Microbial Fuel Cell (MFC), fabricated by 3D printing. Its semi-continuous mode of operation resulted in long-term current profile stability and reproducibility. A linear trend of response was obtained for glutaraldehyde in a concentration range of 5-1000 ppm. After the recovery of the electroactive consortium activity, the MFC-based biosensors were shown to be sensitive towards Ni(II) and Cr(III), at concentrations above 2 mg L-1. To effectively analyze biosensor response, a novel algorithm was proposed, offering advantages for the realization of energy-saving protocols for MFC-biosensor data transmission. Implementation of the device and method, from laboratory test to real environment, can offer a low cost in situ system for detection of water contaminants.

Nanostructural evolution of one-dimensional BaTiO3 structures by hydrothermal conversion of vertically aligned TiO2 nanotubes.

The use of TiO2 nanotube (NT) arrays as templates for hydrothermal conversion of one-dimensional barium titanate (BaTiO3) structures is considered a promising synthesis approach, even though the formation mechanisms are not yet fully understood. Herein we report a nanostructural study by means of XRD and (HR)TEM of high aspect ratio TiO2-NTs hydrothermally converted into BaTiO3. The nanostructure shows two different and well-defined regions: at the top the conversion involves complete dissolution of NTs and subsequent precipitation of BaTiO3 crystals by homogeneous nucleation, followed by the growth of dendritic structures by aggregation and oriented attachment mechanisms. Instead, at the bottom, the low liquid/solid ratio, due to the limited amount of Ba solution that infiltrates the NTs, leads to the rapid crystallization of such a solution into BaTiO3, thus allowing the NTs to act as a template for the formation of highly oriented one-dimensional nanostructures. The in-depth analysis of the structural transformations that take place during the formation of the rod-like arrays of BaTiO3 could help elucidate the conversion mechanism, thus paving the way for the optimization of the synthesis process in view of new applications in energy harvesting devices, where easy and low temperature processing, controlled composition, morphology and functional properties are required.

Antimicrobial activity of basic cholane derivatives. X. Synthesis of 3 alpha- and 3 beta-amino-5 beta-cholan-24-oic acids.

A simple and convenient route to 3 alpha- and 3 beta-amino-5 beta-cholan-24-oic acids was developed via Leuckart-Wallach amination reduction and subsequent acid hydrolysis. Two epimeric formylamino derivatives were produced (alpha and beta), approximately in a 1:1 ratio, as determined by 13C nuclear magnetic resonance spectroscopy. The two isomers were separated by making use of their different solubilities in ethyl ether. The absolute configuration of the two amino acids was assigned by comparison with authentic reference samples.

Simultaneous determination of propranolol or metoprolol in the presence of butyrophenones in human plasma by gas chromatography with mass spectrometry.

A method has been developed for the simultaneous gas chromatographic determination of propranolol or metoprolol and butyrophenones butyrophenones in human plasma in vitro. The drugs were extracted from plasma by solid-phase extraction. Calibration graphs were linear in the 50-300-ng/mL range. The recovery of the compounds was 80-90%. The sensitivity of the method was adequate for the determination of the drugs at toxic concentrations and at therapeutic levels. It is a simple, rapid, and reproducible method for the simultaneous determination of propranolol or metoprolol and some butyrophenones. The minimum detectable concentration was 50 ng/mL with a flame ionization detector and 10 ng/mL with a mass spectrometer detector.

Anomalous origin of the left coronary artery from the pulmonary artery: repair by aortic reimplantation.

From 1980 to 1990, 12 patients (mean age 2.5 years, range 5 months to 9 years) with anomalous origin of the left coronary artery from the pulmonary artery were treated surgically. Five infants were operated upon in the first year of life because of persistent symptoms of congestive heart failure. In all cases, a two-coronary system was constructed by direct aortic reimplantation of the anomalous vessel with no deaths early or late over a follow-up period of up to 10 years. The technique of reimplantation was facilitated by transection of the main pulmonary artery. One patient with severe mitral regurgitation underwent, in addition, a mitral annuloplasty. A pulmonary valvotomy was performed in another patient with associated pulmonary stenosis. Three patients are receiving medication. The reimplanted anomalous left coronary artery was patent in each reevaluated patient (10/12). Left ventricular function improved considerably in all cases. Patients with symptoms should undergo repair soon after diagnosis. Direct aortic reimplantation should be technically feasible in even the smallest infant. Operative mortality is related to preoperative conditions and severity of ischemic damage of the myocardium.

Simultaneous determination of propranolol or metoprolol in the presence of benzodiazepines in the plasma by gas chromatography.

A method for the simultaneous gas chromatographic determination of propranolol and metoprolol and some benzodiazepines in human plasma is described. After the addition of an internal standard, plasma samples were adjusted to pH 8.5 and extracted by SPE chromatography. The analysis was performed by GC with packed and capillary columns, using a FID detector. The quantitative recovery was reported. The assay response was linear in concentration range 50-300 ng/mL for propranolol-benzodiazepine and 100-350 ng/mL for metoprolol-benzodiazepine mixtures.

Simultaneous determination of quinidine and butyrophenones in human plasma by GC-MS.

This report describes a sensitive GC and HRGC-MS procedure for the simultaneous determination of Quinidine and some bytyrophenone drugs in human plasma. The quantitative response is linear from 50-250 ng/ml using Pipamperone as international standard. It is suitable for clinical analysis at therapeutic levels.

Gas chromatographic determination of diisopyramide in the presence of some butyrophenones in human plasma.

A gas chromatographic procedure with flame ionization detection for the simultaneous determination of diisopyramide and butyrophenones in plasma was developed and evaluated. The quantitative analysis of diisopyramide and butyrophenones (BTPs) was performed in gas chromatograph equipped with packed column (glass column packed with 3% of phenylmethyl silicone-20% ph.), with previous Solid Phase Extraction (SPE) of drugs in C18 minicolumns. For all the drugs considered the accuracy of the proposed method has been evaluated through the recovery test which fell in the range 93-99%, once the absence of matrix interferences has been verified. The precision, expressed as coefficient of variation (CV%), has been of the order of 4%. A 15 m x 0.32 mm i.d. crosslinked, 5% phenylmethyl silicone-coated fused-silica column was also quantitatively utilized and samples were injected using the on-column mode.

Antimicrobial activity of basic cholane derivatives, VIII.

Two series of new compounds derived from deoxycholic acid have been synthesized: 3,12-dioxo-5 beta-cholan-24-N-substituted amides and their 3 beta-amino and 3 beta-N-alkylamino derivatives. The first series of five compounds 1-5 carries at C-24 the residue of benzylamine, morpholine, diethanolamine, N,N-diethyl-ethylenediamine, and N-methylpiperazine. The second series of twenty compounds 1A-D - 5A-D was prepared by means of reductive amination starting from the compounds of the first series. This reaction proved to be regioselective and stereospecific: it attacks only C-3 of the steroid moiety and introduces the following axial beta-oriented substituents: amino, methylamino, ethylamino, and benzylamino. The compounds of the first series showed moderate scattered antimicrobial activity; while introduction of the 3 beta-amino and 3 beta-N-alkylamino residue greatly increased activity towards Gram (+) strains; even yeast and fungi appear to be sensitive towards this last series of compounds. The results have been discussed with respect to the nature of the substituents both at C-3 and C-24, the highest activity being associated to the hydrophobicity of these residues.

[Derivatives of lithocholic acid with antibacterial and antifungal activity. IV]. / Derivati dell'acido litocolico ad attività antibatterica ed antifungina. Nota IV.

A series of N-substituted amides of litocholic acid and some N-substituted derivatives of 3 alpha-hydroxy-24-amino-5 beta- cholane were prepared and their in vitro antibacterial and antifungal activity determined against a variety of gram-positive and gram-negative strains and two kinds of mycetes . Some of the tested compounds showed an interesting activity against gram-positive strains and mycetes .

[Pollution levels of the anesthetic agent fluorurate (gas chromatography study)]. / Tassi di inquinamento da agente anestetico fluorurato (Indagine gas-cromatografica).

Using a simple, highly sensitive technique, the rate of pollution due to enflurane in an operating theatre with two beds and two respirators but without an air exchange system has been measured. After much debate and after seven serious cases of viral hepatitis among medical staff, the facility was closed because it was judged to be unusable and because the surgical department using it was moved elsewhere.

Antimicrobial activity of basic cholane derivatives. Part IX.

Twenty new compounds derived from deoxycholic acid have been synthesized. They contain two basic functions: at C-24 (benzylamino, morpholino, diethanolamino, N,N-diethylethylenediamino, N-methylpiperazino) and at beta-C-3 (amino, methylamino, ethylamino, benzylamino). The compounds showed interesting antimicrobial activity, as expressed in terms of the low M.I.C. values (0.9-31-micrograms/ml) against five Gram(+) and four Gram(-) strains, two fungi and one yeast. The compounds inhibit the production of a fluorescent pigment in Pseudomonas aeruginosa: this result suggests that the ability to cross the bacterium cell membrane is the first step of activity. A discussion in terms of structure-activity relationship is reported.