Ab initio structural study of some substituted ibuprofen derivatives as possible anti‐inflammatory agents

The formation energies of a series of substituted derivatives in α‐position of ibuprofen (2‐p‐isobutyl‐phenyl‐propionic acid) are determined, at the ab initio level RHF/6‐311G** with full geometry optimization, in their neutral and anionic forms and in the gas phase and water solution to correlate their physical–chemical properties with their anti‐inflammatory activity. Conformational calculations on the acidic moiety were also performed on five of them. The ab initio methods foresee that all these molecules present two preferred conformations in which the substituting atom in α‐position is lying approximately in the aromatic ring plane, in contrast with the results obtained with semiempirical methods. In this article, the protonation energy in solution, the solvation energy, the HOMO energy of the neutral form, and the lipophilicity will be considered as possible factors of anti‐inflammatory activity. The protonation energy in solution, together with the lipophilicity, are verified to be good activity factors: The smaller the protonation energy and the lipophilicity, the larger the anti‐inflammatory activity. In contrast, the larger the solvation energy, the smaller the activity. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004     

Neutron activation in geochronology: The40Ar/39Ar technique

Fast neutron irradiation of potassium-bearing minerals produces artificial³⁹Ar. Mass spectrometric measurement of the³⁹Ar/⁴⁰Ar ratio allows to calculate a geological age. Stepwise degassing of the sample yields insight into its history. As an example, analysis of a single hornblende from the Valtellina (Italian Alps) reveals an unexpected pre-Alpine history of that region.     

Analytical and multivariate study of roman age architectural terracotta from northeast of Spain

Roman culture employed architectural terracotta made from baked clay as original material to manufacture ceramic pieces. It was often used as a basis for construction of functional and/or decorative elements in roofs, such as plane and curve tiles as well as antefixes with their corresponding “imbrexes”. Some of them are conserved nowadays. They were collected in Roman quarries discovered in old cities and villages sited in the Hispania Citerior (northeast of Spain in Roman age). A study of the origin and manufacturing process (moulding, baking, touching up and painting) of these terracotta pieces has been made on the basis of the data obtained from a physicochemical characterization of samples. The used techniques were mainly flame absorption and emission spectrometry for the elemental analysis (major and minor elements), dilatometry for the study of thermal behaviour, scanning electron microscopy (SEM) for observation of thin layers and X-ray diffraction spectrometry (XRD) for mineralogical composition. In addition, a supervised pattern recognition programme was applied to the results for a selected group of 85 samples and five variables (chromium, copper, lead, nickel and zinc contents). Dilatometry and SEM results showed baking temperatures of these materials below 900 °C and the existence of zones with very different porosity in the same ceramic piece. Results obtained from multielemental analysis and multivariate statistical study by linear discriminant analysis lead us to the following conclusions: (i) the high content of lead found in a large number of antefixes demonstrates the use of lead oxide as an additive in the lime grout treatment, (ii) different contents of Cu, Zn, Cr, and Ni were indicative of the use of varied clay types in the manufacture process (even in the same production centre) as well as of the existence of a pigmentation process, although this last affirmation is not corroborated by the presence of remains of evident painting in the ceramic pieces, (iii) samples can be classified according to the places where these pieces came from and (iv) more variety in their composition was found in Roman age terracotta production centres.     

Speciation of inorganic and organic arsenic in marine sediments from La Coruña estuary

The speciation of As(III), As(V), MMA and DMA in marine sediments from La Coruña estuary is described. The arsenic species have been separated by ion-exchange chromatography and detected by hydride generation atomic absorption spectrometry (HGAAS). The redox potential has been determined in order to relate the concentration of arsenic species to this parameter.     

Thermodynamics of water/β-cyclodextrin system

The thermodynamics of β-cyclodextrin dehydration is investigated, by parallel DSC/TG experiments, on both fully and partially hydrated samples. The apparent dehydration enthalpies per mole of water are impossibly high and this fact suggests that another phenomenon, in addition to the rupture of the β-cyclodextrin/H₂O hydrogen bonds, contributes to the peak area. All the experimental evidence agrees with an ‘interaction model’ which assumes that deydration is accompanied by a slow and reversible rearrangement of the β-cyclodextrin structure.     

Phase transitions and surface stability of the WO3γ-Al2O3 system

The solid state transitions of the WO₃γ-Al₂O₃ system have been investigated in the temperature range 873–1323 K. The formation of α-Al₂O₃ and Al₂(WO₄)₃ phases and the thermal desorption of W(VI) attached to the γ-Al₂O₃ surface have been studied as function of the treatment time. The inhibition of the phase transition to α-Al₂O₃ and therefore the stabilization of the surface has been observed at 1323 K for samples with 7% WO₃ content. This stabilization is critically affected by the tungsten content. An explanation for the stabilization of the alumina surface is proposed.     

Vinyl monomer polymerization mechanism in the presence of trialkylboranes

The polymerization of methyl methacrylate in the presence and in the absence of triethylborane and different inhibitors was carried out. An ethyl radical displacement reaction between the inhibitor radical (produced through the reaction between a radical chain and the inhibitor) and the triethylborane is postulated. This new chain-transfer reaction explains the large excess of inhibitor which must be added in the presence of triethylborane in order to suppress the production of high molecular weight polymer. The results are in agreement with a typical free-radical mechanism.     

Rapid bioanalysis of vancomycin in serum and urine by high-performance liquid chromatography tandem mass spectrometry using on-line sample extraction and parallel analytical columns

A novel high-performance liquid chromatography tandem mass spectrometry (LC/MS/MS) method is described for the determination of vancomycin in serum and urine. After the addition of internal standard (teicoplanin), serum and urine samples were directly injected onto an HPLC system consisting of an extraction column and dual analytical columns. The columns are plumbed through two switching valves. A six-port valve directs extraction column effluent either to waste or to an analytical column. A ten-port valve simultaneously permits equilibration of one analytical column while the other is used for sample analysis. Thus, off-line analytical column equilibration time does not require mass spectrometer time, freeing the detector for increased sample throughput. The on-line sample extraction step takes 15 seconds followed by gradient chromatography taking another 90 seconds. Having minimal sample pretreatment the method is both simple and fast. This system has been used to successfully develop a validated positive-ion electrospray bioanalytical method for the quantitation of vancomycin. Detection of vancomycin was accurate and precise, with a limit of detection of 1 ng/mL in serum and urine. The calibration curves for vancomycin in rat, dog and primate were linear in a concentration range of 0.001-10 microg/mL for serum and urine. This method has been successfully applied to determine the concentration of vancomycin in rat, dog and primate serum and urine samples from pharmacokinetic and urinary excretion studies.     

Thermodynamics of Mixtures Containing Organic Carbonates. Part XV. Application of the Kirkwood-Buff Theory to the Study of Interactions in Liquid Mixtures Containing Dialkyl Carbonates and Alkanes,Benzene, CCl4 or 1-Alkanols

Binary liquid mixtures containing a dialkyl carbonate (dimethyl or diethyl carbonate) and organic solvents such as alkanes, benzene, CCl₄, or 1-alkanols were studied within the framework of the Kirkwood-Buff formalism. The Kirkwood-Buff integrals, linear coefficients of preferential solvation and local mole fractions were calculated. Results were interpreted assuming that the mixtures with alkanes or 1-alkanols are not random mixtures, which can be ascribed to the existence of strong dipolar interactions between like molecules. Systems containing benzene or CCl₄ are both random and more ordered because of the charge transfer or dipole/induced dipole interactions between the polar group of the solute (O–CO–O) and the polarizable solvent molecules. The effect of increasing temperature was also examined.     

Sustainable existence of solid mercury (Hg) nanoparticles at room temperature and their applications

Although liquid mercury (Hg) has been known since antiquity, the formation of stable solid nano forms of Hg at room temperature has not been reported so far. Here, for the first time, we report a simple sonochemical route to obtain solid mercury nanoparticles, stabilized by reduced graphene oxide at ambient conditions. The as-formed solid Hg nanoparticles were found to exhibit remarkable rhombohedral morphology and crystallinity at room temperature. Extensive characterization using various physicochemical techniques revealed the unique properties of the solid nanoparticles of Hg compared to its bulk liquid metal phase. Furthermore, the solid nature of the Hg nanoparticles was studied electrochemically, revealing distinctive properties. We believe that solid Hg nanoparticles have the potential for important applications in the fields of electroanalytical chemistry and electrocatalysis.

Formation of the stable solid mercury nanoparticles by acoustic cavitation and their electrochemical activity compared to its bulk liquid metal.