A Theoretical Study of LiHe+ n , NaHe+ n , and MgHe+ n Complexes, with n=1, 2, 3, 4

The LiHe⁺ _n , the NaHe⁺ _n , and the MgHe⁺ _n complexes with n=1, 2, 3, 4 were studied using ab initio calculations with the MP2/6-311+G(3df, 3pd) method. The complexes are found to be stable. For the n=1 complexes, previous results were available and the calculations performed are in good agreement with those results. This lends credibility to the results obtained for the complexes with higher n.     

Interdisciplinary study on pottery experimentally impregnated with wine

Experimentally developed ceramic pots, with two different sizes of grain, were half-filled with wine and subjected to thermal alteration at constant elevated temperature ((60 ± 2)°C) in darkness for 12 weeks. This work sought to characterise the samples thereby obtained from chemical and mineralogical perspectives using scanning electron microscopy and an energy-dispersive X-ray microanalysis system (SEM-EDX), Fourier transform infrared spectroscopy (FTIR) and capillary electrophoresis (CE) with UV detection as an alternative to chromatographic methods, due to its good resolution, automation, simplicity, high speed, low consumption of chemicals and short time required for sample preparation. The capillary electrophoresis method was used for the detection of five wine biomarkers: succinic acid, malic acid, tartaric acid, citric acid and lactic acid. In general, it was noted that the fine-grained ceramic assortment retained the organic material better than the coarser-grained ceramics. An interesting observation derived from this study was that not only could tartaric acid be considered as a biomarker for wine residues in archaeological pottery, but malic acid could also act similarly for white wine and lactic acid for red wine.     

Mesomorphic behaviour and TSDC measurements of ortho-metallated palladium(II) and platinum(II) complexes with S,O-donor co-ligands

A series of ortho-metallated Pd and Pt complexes containing an imine ligand carrying three alkoxy chains and N-benzoylthiourea derivatives as co-ligands were prepared and their liquid crystalline properties investigated. Their structures were assigned based on elemental analysis, IR and ¹H NMR spectroscopy, whereas thermal properties were investigated by differential scanning calotimetry and polarising optical microscopy. All the compounds exhibit monotropic transitions involving nematic and smectic A phases, with the mesomorphic behaviour strongly related to the type of N-benzoylthiourea as well as the metal centre used. The thermally stimulated depolarisation current technique was employed to determine the conduction mechanism, phase transition temperature and the activation energies for one of the ortho-metallated Pd complexes.     

Screening the thermal stability of carotenoids-α lactalbumin complex by spectroscopic and molecular modeling approach

Sea buckthorn is a natural food ingredient rich in carotenoids, tocopherols, sterols, flavonoids, lipids, vitamins, tannins and minerals. In this study, we investigated the themostability of the complex formed between α-lactalbumin (α-LA) with carotenoids from sea buckthorn berries extract (CSB) in the temperature range of 25°C to 100°C. The heat induced conformational changes of the α-LA-CSB complex were studied by using fluorescence and molecular modeling techniques. Phase diagram indicated the presence of more than one structurally distinct species as an indicator that temperature influenced the conformation of α-LA. Intrinsic fluorescence studies revealed that carotenoids trapped into the core of α-LA do not bind in locations close to tryptophan (Trp) residues. The synchronous spectra indicated that the interaction between α-LA and CSB had no apparent influence on the local conformation of Trp and tyrosine (Tyr) microenvironments within protein structure. Quenching studies with acrylamide showed that Trp residues had the highest exposure at 80°C, being least accessible to quencher at 60°C. In agreement with the fluorescence spectroscopy observations, the in silico analysis at single molecules level indicated a significant increase of 46.42 Å² and 80.07 Å² of the total accessible surface area of Trp and Tyr residues, respectively with the temperature increase from 25°C to 90°C. Concerning the thermodynamic properties of the α-LA-β-carotene model, the molecular modeling results indicate that the thermal treatment is not favorable for preserving the stability of the complex.     

Spectral Investigation of Phosphorus Compounds in Spinacia Oleracea Using Fourier Transform Infrared Method

The study uses the Fourier transform infrared spectroscopy method to evaluate the influence of phosphogypsum from the soil on the growth and accumulation of nutrients in Spinacia oleracea. Attenuated total reflectance spectra of Spinacia oleracea roots and stems originated from plants cultivated on 28% to 52% phosphogypsum enriched soil have been studied in the 4000–600 cm^?1 area. The structure of the infrared absorption bands for spinach roots and stems and for the soil where plants were grown was analyzed. Thus, it was observed that phosphorus–oxygen bonds contribution can be identified both in roots and stems absorption spectra. The significance of the research is the possibility to use the infrared investigation as rapid technique, particularly useful for agriculture, to study the extraction and assimilation process of the compounds containing phosphorus and nitrogen from the soil in which the spinach seedlings grew. In the case of this study, it was observed that the absorption of phosphorus in the spinach roots and stems has not the same effect. The analysis of obtained data indicated that the assimilation of phosphorus from phosphogypsum enriched soil induces changes in spinach roots structure that are most likely due to an increase synthesis of proteins, rather than to a decrease in carbohydrates quantity.     

Quantitative determination of gas mixture composition by gas chromatography—New approach

Summary A new method has been developed for the quantitative determination of gas mixture composition where air penetration during gas sample collection would lead to erroneous results. It requires the use of a stationary phase that separates gas sample components and the air and involves 4–5 analyses of samples of equal volumes containing different amounts of air. By graphical extrapolation of the air peak area (S _air ) as a function of the peak areas of the individual components (S _comp ) the areas for these components in the absence of air can be obtained forS _air =0. Using calibration curves for the pure gas components the true quantitative composition of the gas mixture is estimated.     

Luminescent cyclometallated platinum(II) complexes with N-benzoyl thiourea derivatives as ancillary ligands

A series of cyclometallated 2-phenylpyridine Pt(II) complexes having N-benzoyl thiourea derivatives as ancillary ligands were prepared and characterised by elemental analysis, IR and UV–Vis spectroscopy, ¹H and ¹³C NMR spectroscopy as well as by X-ray diffraction on single-crystal. All complexes were obtained as a single isomer with N atom of the 2-phenylpyridine ligand and S atom of the N-benzoyl thiourea derivatives coordinated in trans positions to the platinum metal as evidenced by using X-ray crystallography and NMR spectroscopy. All Pt(II) complexes show good luminescence properties at room temperature, both in dichloromethane solution and in solid state.     

Study on the influence of PTFE particle size on the polymer thermal behavior: I. Melting

The influence of the size of poly(tetrafluoroethylene) (PTFE) particles, obtained from the formed polymer (bar) by cutting on the fusion was studied in order to get information on the polymer breaking consequence.Three fractions of particle diameters between 1.62–0.42 mm were submitted to DSC in nitrogen, DTA in air and DRX analyses and the results compared to those obtained with the non-processed formed polymer and PTFE mentioned in literature.The study on the heating rate influence on the melting temperature range (T) and the specific heat of fusion (Q/J g^–1) carried out with the fraction of 0.82 mm diameter afforded a method for estimating the polymer specific caloric capacity by means of DSC data.This revised version was published online in November 2005 with corrections to the Cover Date.     

Polyphenols,radical scavenger activity,short-chain organic acids and heavy metals of several plants extracts from “Bucharest Delta”

Some plants collected (Mentha aquatica, Bidens tripartita and Ambrosia artemisiifolia) from an unusual habitat developed in recent years in Bucharest (the so-called “Bucharest Delta”) and the contents of polyphenolic compounds, short-chain organic acids and heavy metals, and radical scavenger activity, were determined. 12 polyphenolic compounds and 7 short-chain organic acids were quantified using high-performance liquid chromatography and capillary electrophoresis; Mentha aq. extracts presented the highest levels of rosmarinic acid (1.58 mg g^?1) and ferulic acid (2.84 mg g^?1) and Bidens extracts presented the highest concentrations of chlorogenic acid (0.44 mg g^?1); the same extracts contain the most important levels of luteolin (0.52 mg g^?1) or other flavonoids. All the heavy metals detected in the plants studied were found in very low levels (the highest was Pb(II) in Mentha aquatica, (12.84 ± 0.48) µg kg^?1). The study sought to identify the active compounds and some contaminants in plants collected from the “Bucharest Delta” with the intention of eventual exploitation of the habitat and to enhance the knowledge of such human-modified ecosystems.