Syntheses of 5‐alkylthio‐1,3‐diaryl‐1,2,4‐triazoles

Arylation of the readily available 3‐alkythio‐5‐aryl‐1,2,4‐triazoles gave 5‐alkylthio‐1,3‐diaryl‐1,2,4‐triazoles in moderate yield. The structures of the latter were confirmed by NOE and ¹³C‐NMR.     

Nuclear spin relaxation study of aqueous raffinose solution in the presence of a gadolinium contrast agent

Paramagnetic enhancement of nuclear spin-lattice relaxation rates (PREs) was measured in aqueous solution of the trisaccharide raffinose in the presence of a gadolinium(III) complex, GdDTPA-BMA, used as a magnetic resonance imaging contrast agent. The relaxation enhancement of aqueous protons was measured over a broad range of magnetic fields, using field-cycling apparatus in addition to conventional spectrometers. The nuclear magnetic relaxation dispersion profile thus obtained was interpreted with a recently developed model, allowing for both inner- and outer-sphere relaxation. The relaxation enhancement for the carbon-13 nuclei in raffinose was studied under high-resolution conditions at three magnetic fields, whereas the sugar proton PRE was measured at two fields. The PRE of the sugar nuclei could be interpreted in a consistent way, assuming that it was caused by the outer-sphere mechanism. The electron spin relaxation was found to be a less important source of modulation of the electron-nuclear dipole-dipole interaction than the mutual translational diffusion.     

Cooperative effects in phospholipid monolayers induced by a peptide from HIV-1 capsid protein

The study of interactions between biological molecules and model membranes is essential for the understanding of a number of physiological mechanisms involved in viral infections and dissemination. In this paper, the analysis of the interaction between a peptide from the p24 protein of Human Immunodeficiency Virus type 1 (HIV-1) and a phospholipid monolayer has pointed to a cooperative response in which very small amounts of peptide p24-1 (e.g. 0.05 mol%) can lead to measurable effects. Monolayer surface pressure and surface potential isotherms were affected for peptide concentrations as low as 0.05 mol%, with saturation at 0.5 mol%. The expansion effect from p24-1 is confirmed by changes in morphology of the monolayers using Brewster angle microscopy. Even though p24-1 is disordered in aqueous solutions, the interaction with dipalmitoyl phosphatidylcholine (DPPC) causes it to adopt an alpha-helix structure, as shown by circular dichroism (CD) data for multilamellar vesicles (MLV). The expansion of the phospholipid monolayer in a cooperative way may imply that p24-1 has potential antiviral activity, by participating in the cell rupture, with no need of specific receptors in the membrane.     

Comparative Studies on the Behavior of 3-Amino-2-phenyl-4(3 H )-quinazolinone Towards Some Organophosphorus Reagents

The reaction of 3-amino-2-phenyl-4(3H)-quinazolinone with oxovinylidenetriphenylphosphorane afforded 5-phenylpyrazolo[1,5-c] quinazoline-2(3H)-one and triphenylphosphine oxide. On the other hand, when quinazolinone reacts with phosphorus ylides, the corresponding phosphorane adducts were obtained. Moreover, quinazolinone reacts with trisdialkylaminophosphines to give the new (dialkylamino)oxophosphonium dipolar products. Possible reaction mechanisms are considered and the structural assignments are based on analytical and spectroscopic results.     

Evolved Gas Analysis‐Mass Spectrometry to Identify the Earliest Organic Binder in Aegean Style Wall Paintings

An organic binder was identified in the painted fragments from the Canaanite palace of Tel Kabri, Israel. Recently dated to the late 18th century B.C.E. by ¹⁴C, Tel Kabri is the most ancient of the Eastern Mediterranean sites in which Aegean style paintings have been found. The application of pigments was suspected to be using an organic binding medium, particularly for the Egyptian Blue pigment. Samples of blue paint were examined using evolved gas analysis‐mass spectrometry (EGA‐MS) in order to overcome the analytical challenges imposed by highly degraded aged proteinaceous materials. Egg was identified as the binder based on the presence of hexadecanonitrile and octadecanonitrile, confirming the use of a secco painting technique. Lysozyme C from Gallus gallus was detected by proteomics analysis, confirming the presence of egg. To our knowledge, this is the earliest use of egg as a binder in Aegean style wall paintings.     

A Comparison of Tissue Spray and Lipid Extract Direct Injection Electrospray Ionization Mass Spectrometry for the Differentiation of Eutopic and Ectopic Endometrial Tissues

Recent research revealed that tissue spray mass spectrometry enables rapid molecular profiling of biological tissues, which is of great importance for the search of disease biomarkers as well as for online surgery control. However, the payback for the high speed of analysis in tissue spray analysis is the generally lower chemical sensitivity compared with the traditional approach based on the offline chemical extraction and electrospray ionization mass spectrometry detection. In this study, high resolution mass spectrometry analysis of endometrium tissues of different localizations obtained using direct tissue spray mass spectrometry in positive ion mode is compared with the results of electrospray ionization analysis of lipid extracts. Identified features in both cases belong to three lipid classes: phosphatidylcholines, phosphoethanolamines, and sphingomyelins. Lipids coverage is validated by hydrophilic interaction liquid chromatography with mass spectrometry of lipid extracts. Multivariate analysis of data from both methods reveals satisfactory differentiation of eutopic and ectopic endometrium tissues. Overall, our results indicate that the chemical information provided by tissue spray ionization is sufficient to allow differentiation of endometrial tissues by localization with similar reliability but higher speed than in the traditional approach relying on offline extraction.

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Decomposition of Triethylamine Over Acid Catalysts

The effect of hydrochloric acid, boric acid, and silica content in alumina on its catalytic activity towards the decomposition of triethylamine was investigated at 310°, 320°, and 330°. The study was carried out in a flow system and the reaction product was analyzed chromotographically. Ethylene formation is a zero order reaction independent of the partial pressure of triethylamine. Treating γ-alumina with hydrochloric acid increases its catalytic activity towards ethylene formation whereas silica-alumina is less active than γ-alumina. Boric acid-treated alumina has the same activity of γ-alumina. Formation of ethylene from preadsorbed triethylamine was studied. The similarity between reactions of aliphatic alcohols and amines over acid catalysts is concluded.     

Combination of solid-phase extraction-hollow fiber for ultra-preconcentration of some triazole pesticides followed by gas chromatography-flame ionization detection

In this study, an extraction and preconcentration technique using solid-phase extraction (SPE) along with hollow fiber (HF) has been developed as an ultra-preconcentration technique for some triazole pesticides in aqueous samples. Triazole pesticides were employed as model compounds to assess the method and were monitored by gas chromatography-flame ionization detection (GC-FID). Initially, an aqueous solution of target analytes was passed through an RP-8 SPE cartridge and then the adsorbed analytes were eluted with μL amounts of toluene. The collected elute was slowly introduced into an HF that had one end blocked. This allowed precipitation inside the lumen and pores of the HF. Finally, the obtained HF was mounted on a home-made solid-phase microextraction syringe and entered into the GC injection port for thermal desorption-GC analysis. The effect of various experimental parameters including injection port temperature, desorption time, state of HF, washing solvent, elution solvent and its volume, sample volume, etc. were investigated for finding the optimum conditions. The calibration graphs were linear in the ranges of 2-1000 ng/mL (penconazole and hexaconazole), 5-1000 ng/mL (tebuconazole), 15-1000 ng/mL (triticonazole) and the detection limits (LODs) ranged from 0.6 to 4.5 ng/mL. The enhancement factors were in the range of 870-950. The relative standard deviations (RSD%) for five repeated experiments (C=250 ng/mL of each pesticide) varied from 4.5 to 8.7%. The relative recoveries obtained for analytes in grape juice samples, spiked with different levels of each pesticide, were in the range of 87-119%.     

Genetic diversity and haplotype structure of 21 Y‐STRs,including nine noncore loci,in South Tunisian Population: Forensic relevance

Y chromosome STRs (Y‐STRs) are being used frequently in forensic laboratories. Previous studies of Y‐STR polymorphisms in different groups of the Tunisian population identified low levels of diversity and discrimination capacity (DC) using various commercial marker sets. This definitely limits the use of such systems for Y‐STRs genotyping in Tunisia. In our investigation on South Tunisia, 200 unrelated males were typed for the 12 conventional Y‐STRs included in the PowerPlex® Y System. Additional set of nine noncore Y‐STRs including DYS446, DYS456, DYS458, DYS388, DYS444, DYS445, DYS449, DYS710, and DYS464 markers were genotyped and evaluated for their potential in improving DC. Allele frequency, gene diversity, haplotype diversity (HD), and DC calculation revealed that DYS464 was the most diverse marker followed by DYS710 and DYS449 markers. The standard panel of 12 Y‐STRs (DC = 80.5%) and the nine markers were combined to obtain DC of 99%. Among the 198 different haplotypes observed, 196 haplotypes were unique (HD = 99.999). Out of the nine noncore set, six Y‐STRs (DYS458, DYS456, DYS449, DYS710, DYS444, and DYS464) had the greatest impact on enhancing DC. Our data provided putative Y‐STRs combination to be used for genetic and forensic applications.