High-speed capillary gas chromatography for determination of inhalation anesthetics

To increase sample throughput for GC analysis of inhalation anaesthetics without affecting the separation of nitrous oxide (N2O) and halogenated anaesthetics (sevoflurane, isoflurane and halothane), we explored the effectiveness of a tailor-shortened (12 m) PlotQ capillary column and developed a high-speed version of a previously reported GC technique (involving chromatographic separation of analytes using a GC-MS system, coupled with a selected ion monitoring (SIM) method to increase sensitivity). Efficient separation and repeatable results were achieved at a reduced runtime of approximately 7 min (versus 18 min with the original method) at a carrier gas flow of 1.5 ml/min. This approach should more than double the previous throughput.     

Ring opening of benzoxazoles with allylic grignard reagents: synthesis of n-diallylalkyl-o-aminophenols.

The title benzoxales $\text{1a-d}$ react cleanly with allylic Grignard reagents $\text{2a-c}$ undergoing ring opening to give good yields of N-diallyl- alkyl-$\text{o}$-aminophenols $\text{3a-m}$. A plausible mechanism is discussed.     

A computational study of the effect of C-lithiation on the NMR properties (chemical shifts and coupling constants) of aziridines

A DFT (B3LYP/6-311++G(d,p) study of a series of N-H, N-methyl and N-propyl aziridines and their C-lithium derivatives has been carried out in order to explore their configurational as well as their NMR properties (¹H and ¹³C). The results agree fairly well with experimental observations [Org Lett 9:1263, 2007 and J Org Chem 73, 2008 (73:3197)] and reveal the existence of lithium-N(lone pair) and lithium C(aromatic) interactions. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Tunable electronic coupling in iron-chromium mixed-valence ions of methylated Cp-indene ligands

A series of heterobimetallic η⁶-[(ferrocenyl)indene]-Cr(CO)₃ complexes differing for the position of the ferrocenyl group, 1-(ferrocenyl)indene and 2-(ferrocenyl)indene, and the degree of indene methylation (tetramethyl- and hexamethyl-) have been prepared and studied with the aim to stabilise the mono- and dications generated by chemical and electrochemical oxidation, and at same time to tune the metal-metal electronic coupling in the mixed-valence cations. The magnitude of electronic delocalisation and spin density in the cations have been monitored by means of optical techniques (UV-Vis, near-IR, mid-IR) and EPR spectroscopy. The results have been rationalised in the framework of Marcus-Hush theory and at quantum chemistry level by DFT and TD-DFT methods, establishing that a metal-to-metal electronic coupling occurs the magnitude of which depends on the degree of indene methylation.     

Combining piracetam and lithium salts: ionic co-crystals and co-drugs?

Mechanochemical reaction of solid piracetam with the inorganic salts LiCl and LiBr yields ionic co-crystals which are also co-drugs, characterized by markedly different thermal properties with respect to pure components, also depending on the method for preparation and/or conditions of measurements; single crystal and powder X-ray diffraction at variable temperatures, DSC, TGA, hot stage microscopy (HSM) and intrinsic dissolution rate have been used to fully characterize the solid products.     

A chemometric approach based on a novel similarity/diversity measure for the characterisation and selection of electronic nose sensors

Electronic nose sensor signals provide a digital fingerprint of the product in analysis, which can be subsequently investigated by means of chemometrics. In this paper, the fingerprint characterisation of electronic nose data has been studied by means of a novel chemometric approach based on the partial ordering technique and the Hasse matrix. This matrix can be associated to each data sequence and the similarity between two sequences can be evaluated with the definition of a distance between the corresponding Hasse matrices. Since all the signals achieved along time are intrinsically ordered, the data provided by electronic nose can be also considered as sequential data and consequently characterized by means of the proposed approach. The similarity/diversity measure has been here applied in order to characterize the class discrimination capability of each electronic nose sensor: extra virgin olive oil samples of different geographical origin have been considered and Hasse distances have been used to select the sensors which appear more able to discriminate the olive oil origins. The distance based on the Hasse matrix has showed some useful properties and proved to be able to link each electronic nose time profile to a meaningful mathematical term (the Hasse matrix), which can be consequently studied by multivariate analysis.     

Ultraviolet Absorption Spectra of Styrene Copolymers. I. Solvent Effects on the Hypochromism of Poly(styrene-co-methyl Methacrylate) at 2695 Å

The use of a UV spectrometer for evaluating the chemical composition of styrene-methyl methacrylate random co-polymers is conditioned by the presence of a marked hypochromism at 2695 Å.

The composition range where the hypochromic effect appears is strongly affected by the solvent employed.

Optical densities at 2695 Å for copolymer solutions in chloroform, dichloroethane, tetrachloroethane, tetrahydrofuran, and dioxane have been determined and compared to the absorbance values of polystyrene solutions. A linear correlation between solvent dielectric constant and copolymer composition corresponding to the maximum hypochromism is found.

Implications involving gel permeation chromatography analyses of styrene copolymers are discussed.     

On the Dirichlet problem for first order partial differential equations. A Baire category approach

((without abstract.)) Received September 22, 1997     

Copper binding agents acting as copper ionophores lead to caspase inhibition and paraptotic cell death in human cancer cells

We report a quantitative structure-activity relationship study of a new class of pyrazole-pyridine copper complexes that establishes a clear correlation between the ability to promote copper accumulation and cytotoxicity. Intracellular metal accumulation is maximized when ligand lipophilicity allows the complex to rapidly cross the membrane. Copper and ligand follow different uptake kinetics and reach different intracellular equilibrium concentrations. These results support a model in which the ligand acts as an ionophore for the metal ion, cycling between intra- and extracellular compartments as dissociated or complexed entities. When treating cancer cells with structurally unrelated disulfiram and pyrazole-pyridine copper complexes, as well as with inorganic copper, the same morphological and molecular changes were reproduced, indicating that copper overload is responsible for the cytotoxic effects. Copper-based treatments drive sensitive cancer cells toward paraptotic cell death, a process hallmarked by endoplasmic reticulum stress and massive vacuolization in the absence of apoptotic features. A lack of caspase activation, as observed in copper-treated dying cells, is a consequence of metal-mediated inhibition of caspase-3. Thus, copper acts simultaneously as an endoplasmic reticulum (ER) stress inducer and a caspase-3 inhibitor, forcing the cell into caspase-independent paraptotic death. The establishment of a mechanism of action common to different copper binding agents provides a rationale for the exploitation of copper toxicity as an anticancer tool.