Formation of pyrimidine-5-carboxaldehydes, 1-aminoethylene-2,2-dicarboxaldehyde and 2-amino-4-anilino-1,3,5-triazine from triformylmethane and amidines

Triformylmethane ( 1 ) reacted with benzamidine, guanidine and S-methylisothiourea to give the corresponding 2-substituted pyrimidines-5-carboxaldehydes. However, reactions of 1 with acetamidine (or for-mamidine) and phenylbiguanide gave the unexpected 1-aminoethylene-2,2-dicarboxaldehyde ( 5 ) and 2-amino-4-anilino-1,3,5-triazine ( 9 ), respectively.     

Reactions of triacetylmethane with monosubstituted hydrazines and amidine analogues. Syntheses of 4-acetyl-3,5-dimethylpyrazole amidinohydrazone and 1,3,5-triazine derivatives

Triacetylmethane ( 1 ) reacts with amidinohydrazines in acidic medium to afford 4-acetyl-3,5-dimethylpyrazole amidinohydrazone derivatives 2,4 . However, a similar reaction of 1 with thiosemicarbazide or semicarbazide led mainly to 3,5-dimethylpyrazole ( 6 ). The great propensity of 1 to hydrolysis accounts for this last transformation, as well as for the fact that with guanidine it led to 2-amino-4,6-dimethylpyrimidine ( 10 ) and with S-methylisothiourea it provided the unexpected 2-amino-4-methyl-6-methylthio-1,3,5-triazine ( 11 ).     

Highly diastereoselective synthetic route to enantiopure beta(2)-amino acids and gamma-amino alcohols using a fluorinated oxazolidine (Fox) as chiral auxiliary

The alkylation reactions of an amide enolate derived from a trifluoromethylated oxazolidine (Fox) chiral auxiliary occur with a complete diastereoselectivity and in good yields with various electrophiles. This reaction provides a versatile and straightforward strategy for the synthesis of beta(2)-amino acids and gamma-amino alcohols in enantiopure form.     

Ex vivo and in vivo diagnosis of C6 glioblastoma development by Raman spectroscopy coupled to a microprobe

The potential of Raman spectroscopy for ex vivo and in vivo classification of normal and glioblastoma brain tumor development was investigated. High-quality spectra of normal and tumor tissues were obtained using a portable Raman spectrometer coupled to a microprobe with a signal integration time of 5 s. Ex vivo results demonstrated that by using the biochemical information contained in the spectra, we were able to distinguish between normal brain features (white and gray matter), invasion, and tumor tissues with a classification accuracy of 100%. Differences between these features resulted from variations in their lipid signal contributions, which probably reflect differences in the level of myelinization. This finding supports the ability of in vivo Raman spectroscopy to delineate tumor margins during surgery. After implanting C6 cells in rat brain, we monitored, in vivo, the development of glioblastoma tumor from days 0 to 20 post-implantation (PI). The classification exhibited a clear separation of the data into two clusters: one cluster was associated with normal brain tissues (cortex), and the second was related to data measured from tumor evolution. The second cluster could be divided into two subclusters, one associated with tumor tissue from 4 to 13 days PI and the second related to tumor tissue from 15 to 20 days PI. Histological analysis reveals that the differences between these two subclusters are: the presence of a massive infiltration zone in the brain tissue from 4 to 13 days PI, and; a maturation of the tumor characterized by the appearance of edematous and necrotic zones, as well as a diminution in the proliferative and invasive area, from 15 days. This work demonstrates the potential of Raman spectroscopy to provide diagnostic information for the early detection of tumors in vivo.     

Efficient electrosynthesis of sulfinic esters via oxidative cross-coupling between alcohols and thiophenols

A new protocol for S O bond formation was developed by electrochemical oxidative cross-coupling between alcohols and thiophenols. With this strategy, a series of valuable sulfinic ester derivatives were synthesized up to 96% yield from basic starting materials. A preliminary mechanistic investigation reveals that this reaction involves oxygen reduction reaction (ORR).     

On the selfsimilar solutions of a diffusion convection equation

This paper is concerned with the equation¶¶ div(| ?u| ^p-2?u)+e| ?U| ^q+bx?U+aU=0, for  x ? \mathbbR^N div(| \nabla u| ^{p-2}\nabla u)+\varepsilon \left| \nabla U\right| ^q+\beta x\nabla U+\alpha U=0,{\rm \ for}\;x\in \mathbb{R}^N ¶¶ where $ p>2,\;q\geq 1,\;N\geq 1, \quad\varepsilon =\pm 1 $ p>2,\;q\geq 1,\;N\geq 1, \quad\varepsilon =\pm 1 and a,b, m \alpha ,\beta, \mu are positive parameters. We study the existence, uniqueness of radial solutions u(r). Also, qualitative behavior of u(r) are presented.     

Combining chemical data with GIS and PCA to investigate Phoenician–Punic Cu-metallurgy

This study focusses on the development and application of an innovative protocol which combines chemical data, GIS (geographical information system) and PCA, involving numeric (chemical composition) and categorical (typology of object, archaeological context, chronology and geographical areas) variables, as a simple tool to help in the visualisation and interpretation of large multidisciplinary datasets on Cu-based alloy archaeological artefacts influenced by Phoenician–Punic contacts. The protocol is a useful tool for highlighting existing connections between specific alloy chemical compositions, the location of the original settlement where the artefact had been produced and the proximity to mining resources, waterways, and allochthonous presence such as, in the specific case of this study, the Phoenician and Punic influence in the Iberian bronze production during the Late Bronze Age–Iron Age. The protocol was tested successfully in a case study concerning the precise dating and provenance of bronze statuettes of unknown age and provenance from the Evora Museum collection in Southern Portugal where it confirmed and further refined earlier hypotheses based solely on archaeological and/or chemical studies. The results were interpreted with a unique perspective, to validate the GIS system in combination with experimental chemical-physical data to yield the identification of metallurgical sites of bronze production.     

A fast approach of nonparametric elastic image registration problem

In this paper, we present a fast algorithm of the nonparametric elastic image registration using a simple implementation of the Range Restricted GMRES (RRGMRES) method. This approach differs from the others in the fact that it is specified to the tridiagonal block matrix type to resolve a nonsymmetric linear system. In what follows, we prove existence and uniqueness of minimizer of the elastic registration problem and present the corresponding discrete problem by employing a finite difference scheme. The accuracy of the proposed method is demonstrated on different image registration examples; we also show the speedup of the proposed approach by calculating the corresponding CPU time and compared it with the classical elastic registration method.     

Ionic Complexes of Biotechnological Polyacids with Cationic Surfactants

Summary: Stoichiometric complexes of biotechnological poly(γ-glutamic) acid and poly(β,L -malic) acid with alkyltrimethylammonium surfactants of long alkyl chains could be readily prepared in aqueous medium. They adopt a biphasic layered structures in which the main chain and the side chain alternate with nanometric periodicity. Alkyl side chains show reversible melting that involves generation of mesophases. Complexes degraded by water by different mechanisms depending on the constitution of the main chain; the polymalic complexes underwent surface erosion whereas the polyglutamic ones degraded in bulk. Erythromycin could be homogenously loaded into the paraffinic subphase of the complexes and delivered upon incubation under physiological conditions in parallel to the hydrolysis of the polymer.     

Nickel Coated Graphite Microparticle Based Electrodes for Carbon Dioxide Reduction in MonoethanolamineMedium

A composite electrode that contains home-made nickel coated carbon micro-particles as active materials and epoxy binder has been prepared. The surface morphology, elemental composition and size distribution of microparticles were investigated using SEM, EDS, AAS, micro Raman spectroscopy and appropriate seizer apparatus. The prepared micro-particles appeared monodispers with 33 μm most numerous particle size diameter and with 10.1 w/w % Ni content. Conventional electrochemical methods like impedance spectroscopy and voltammetry as well as scanning electrochemical microscopy (SECM) were used for investigation the properties of the composite electrodes. It has been proved that the electrode can be well used for electro-catalytic reduction of CO₂ directly in aqueous mono-ethanol amine (MEA) solution that frequently are applied for capturing it from power plant flue gases. SECM measurements showed that presence of dissolved CO₂ hinders the hydrogen evolution in aqueous MEA solution.