Synthesis of novel 4-amino-1,4-benzodiazepine-2,5-diones for anticonvulsant testing

A series of novel 4-amino-1,4-benzodiazepine-2,5-diones was synthesized via two pathways. The first method involved reductive alkylation of unsymmetrical hydrazines with glyoxylic acid, followed by Fisher esterification. The resulting N-aminoglycinate ethyl ester was subsequently o-nitrobenzoylated, reduced, and thermally cyclized to obtain 4-dialkylaminobenzodiazepinones. In the second method methylhydrazine was acetylated at N_α then benzoylated at N_β to give 1,2-diacylhydrazines. Alkylation with ethyl bromoacetate and reduction of the nitro group, followed by thermal cyclization yielded 4-acetamidobenzodiazepinones. All title compounds were evaluated in mice in MES seizure and sc Met seizure threshold tests for anticonvulsant activity, and in the rotorod test for neurotoxicity. Activity and toxicity were both minimal.     

Optical and Electrical Properties of Polymerizing Plasmas and Their Correlation with DLC Film Properties

Diamond-like carbon (DLC) films were grown from radiofrequency plasmas of acetylene-argon mixtures, at different excitation powers, P. The effects of this parameter on the plasma potential, electron density, electron temperature, and plasma activity were investigated using a Langmuir probe. The mean electron temperature increased from about 0.5 to about 7.0 eV while the mean electron density decreased from about 1.2 × 10⁹ to about 0.2 × 10⁹ cm^–3 as P was increased from 25 to 150 W. Both the plasma potential and the plasma activity were found to increase with increasing P. Through actinometric optical emission spectrometry, the relative concentrations of CH, [CH], and H, [H], in the discharge were mapped as a function of the applied power. A rise in [H] and a fall in [CH] with increasing P were observed and are discussed in relation to the plasma characteristics and the subimplantation model. The optical properties of the films were calculated from ultraviolet-visible spectroscopic data; the surface resistivity was measured by the two-point probe method. The optical gap, E _G, and the surface resistivity, _s, fall with increasing P. E _G and _s are in the ranges of about 2.0–1.3 eV and 10¹⁴–10¹⁶ /, respectively. The plasma power also influences the film self-bias, V _b, via a linear dependence, and the effect of V _b on ion bombardment during growth is addressed together with variation in the relative densities of sp² and sp³ bonds in the films as determined by Raman spectroscopy.     

O2 and organic semiconductors: Electronic effects

Contact potential difference (CPD) measurements of the relative work functions of a range of organic semiconductor thin films show that oxygen causes effective p-type doping (with work functions increasing 0.1–0.3 eV). This doping effect is found to be reversible by exposure to high vacuum or heating in inert atmosphere. The mechanism of doping is explained by a model, based on a reversible formation of an O-substrate charge transfer state. Conductivity measurements of p-phthalocyanine films at variable temperatures support this doping model. The oxygen doping effect is consistent with filling of tail states in the gap, as shown by the increase of activation energy of hole transport with decreased O-doping, and by the good fit between experimental data and simulations of the in-gap density of states. A model hybrid solar cell configuration also shows the effect of doping by O₂ and corroborates the fact that O-doping fills the tail states in the system.     

Laser-printed lithium-sulphur micro-electrodes for Li/S batteries

A novel path for the preparation of electrodes for lithium-sulphur cells was developed using a very fast laser-printing setup for the direct and dry i.e., solvent-free transfer of electrode materials onto the current collectors. Model electrodes could be prepared at very small dimensions enabling these batteries to be used even in portable small devices. The initial specific charge was remarkably high at about 1300 A h kg^?1 (relating to the active material content of the electrode) with a loss of specific charge of about 75% after about 400 cycles at 1C. In addition, the dry transfer technique has highly beneficial effects on the environmental sustainability and, therefore, supports the concept of the use of “green” power storage.     

Storage stability studies for tributyltin determination in human urine samples using headspace solid‐phase microextraction and gas chromatography mass spectrometry

A headspace solid‐phase micro‐extraction (HS‐SPME) method was employed in order to study the effect of storage conditions of human urine samples spiked with tributyltin (TBT) using gas chromatography and mass spectrometry. To render the analyte more volatile, the derivatization (ethylation) was made in situ by sodium tetraethylborate (NaBEt₄), which was added directly to dilute unpreserved urine samples and in buffers of similar acidity. The stability of TBT in human urine matrix was compared with the stability of TBT in buffer solutions of similar pH value. Critical parameters of storage conditions such as temperature and time, which affect the stability of TBT in this kind of matrix, were examined extensively. The tests showed that the stability of TBT remains practically satisfactory for a maximum of 2 days of storage either at +4 or 20°C. Greater variations were observed in the concentration of TBT in human urine samples at +4°C and lower ones at ?20°C over a month's storage. The freeze–thaw cycles have negative effect on the stability and should be kept to a minimum. The results from spiked urine samples are also discussed in comparison to those acquired from buffer solutions of equal TBT concentration. Copyright © 2012 John Wiley & Sons, Ltd.