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The Publisher regrets that this article is an accidental duplication of an article that has already been published, https://doi.org/10.1016/j.ad.2022.02.024. The duplicate article has therefore been withdrawn.

A method for identifying Co, Cu, Sb, Sn, Fe, Zn, and Zr pigments in glasses using square‐wave voltammetry as the detection mode is described. It is based on the abrasive attachment of glass microsamples to graphite/polyester composite electrodes. Sample amounts less than 1 μg are used allowing for the study of archaeological samples. In all cases well‐defined anodic stripping peaks corresponding to the oxidation of metal deposits generated at potentials ranging from −0.6 to −1.6 V (vs. SCE) are obtained. This response is in agreement with that displayed by the corresponding metal oxides. Quantitative estimates of the relative population of metal ions in glasses are obtained from peak area measurements with an accuracy comparable to that obtained with SEM/EDX.

The simultaneous determination of chromium and cobalt in water samples has been studied. Chemiluminescence registers based on the luminol–hydrogen peroxide reaction have obtained by a batch procedure. PLS algorithms have employed to model the time-response (formation and destruction of emitter).

An in-depth chemical-analytical study has been performed on biscuit and mortar from 17th–18th century tiles from a mediaeval hermitage in the province of Valencia (Spain). Representative samples were chosen from the tile fragments available, using appearance, essentially color and consistency, as the criterion. The chemical composition was analyzed by X-ray fluorescence of the samples in the form of glass disks after a previous qualitative study to choose the standard materials for calibration and the experimental conditions used in the analysis. X-ray diffraction of the samples provided information about the mineralogical composition which was consistent with the firing of the original materials; it also gave information about the range of temperatures used in the firing. From thermal gravimetric analysis of the limestone, and from historical considerations, it was possible to deduce the raw materials used and their approximate composition in the tiles. In the same way it was possible to determine the nature of the mortars used to fix the tiles. Cyclic voltammetric study of the iron(II) and iron(III) system in the biscuit showed the simultaneous presence of both oxidation states, corroborating the results.

To establish correlation between structural properties (charge, composition, and conformation) and membrane penetration capability, the interaction of epitope peptide−carrier constructs with phospholipid model membranes was studied. For this we have conjugated a linear epitope peptide, ¹¹⁰FWRGDLVFDFQV¹²¹ (110−121), from VP3 capside protein of the Hepatitis A virus with polylysine-based branched polypeptides with different chemical characteristics. The epitope peptide elongated by one Cys residue at the N-terminal [C(110−121)] was attached to poly[Lys-(dl-Alam-Xi)] (i < 1, m ≈ 3), where x = &slshcir; (AK), Ser (SAK), or Glu (EAK) by the amide-thiol heterobifunctional reagent, 3-(2-pyridyldithio)propionic acid N-hydroxy-succinimide ester. The interaction of these polymer−[C(110−121)] conjugates with phospholipid monolayers and bilayers was studied using DPPC and DPPC/PG (95/5 mol/mol) mixture. Changes in the fluidity of liposomes induced by these conjugates were detected by using two fluorescent probes 1,6-diphenyl-1,3,5-hexatriene (DPH) and sodium anilino naphthalene sulfonate (ANS). The binding of conjugates to the model membranes was compared and the contribution of the polymer component to these interactions were evaluated. We found that conjugates with polyanionic/EAK−[C(110−121)] or polycationic/SAK−[C(110−121)], AK−[C(110−121)]/character were capable to form monomolecular layers at the air/water interface with structure dependent stability in the following order:  EAK−[C(110−121)] > SAK−[C(110−121)] > AK−[C(110−121)]. Data obtained from penetration studies into phospholipid monolayers indicated that conjugate insertion is more pronounced for EAK−[C(110−121)] than for AK−[C(110−121)] or SAK−[C(110−121)]. Changes in the fluorescence intensity and in polarization of fluorescent probes either at the polar surface (ANS) or within the hydrophobic core (DPH) of the DPPC/PG liposomes suggested that all three conjugates interact with the outer surface of the bilayer. Marked penetration was documented by a significant increase of the transition temperature only with the polyanionic compound/EAK−[C(110−121)]. Taken together, we found that the binding/penetration of conjugates to phospholipid model membranes is dependent on the charge properties of the constructs. Considering that the orientation and number of VP3 epitope peptides attached to branched polypeptides were almost identical, we can conclude that the structural characteristics (amino acid composition, charge, and surface activity) of the carrier have a pronounced effect on the conjugate−phospholipid membrane interaction. These observations suggest that the selection of polymer carrier for epitope attachment might significantly influence the membrane activity of the conjugate and provide guidelines for adequate presentation of immunogenic peptides to the cells.

To prepare liposomes containing a synthetic hepatitis A virus antigen (HAV) [VP3(110–121)] as a vaccine, the miscibility of this peptide (with negative net charge) with a neutral lipid [dipalmitoylphosphatidylcholine (DPPC)], a negatively charged lipid [dipalmitoylphosphatidylglycerol (DPPG)], and a positively charged lipid [Stearylamine (SA)] was studied through compression isotherms of monolayers. Mixtures with DPPC and SA showed a low degree of interaction with the peptide, the composition of the monolayer being stable through compression. For DPPG-containing monolayers larger positive deviations from ideality were found, and the peptide was squeezed out from the monolayer at a DPPG/VP3(110–121) mole fraction of 0.8/0.2. All this suggests that besides hydrophobic interactions between the peptide and the lipid, electrostatic forces also play a role; thus it seems that neutral and positively charged lipids would be more suitable for preparing stable liposomes with VP3(110–121).

Oils and fats start decomposing from the moment they are isolated from their natural environment. Heating accelerates oxidative rancidity and frying at high temperatures produces thermal degradation with the formation of decomposition products, such as aldehydes, ketones, free acids and hydroxilic compounds that in high levels can be harmful to human health. The decomposition products formed up to 300°C were determined by means of 1H-NMR spectroscopy and an FTIR spectroscopic method was developed for the quantification of carbonyl compounds generated during heating. The results show that there is a formation of carbonyl compounds starting at 150°C and when the sample was heated at 300°C for 40min, the following contents (expressed as butyraldehyde mass fraction) were found: olive oil 10.5%, sunflower oil 11.3%, corn oil 3.0%, seeds oil(sunflower, safflower and canola seed) 6.6% and lard 3.5%.

The oxidative deterioration of culinary oils and fats during episodes of heating associated with normal usage (80°C–300°C, 20–40min) was monitored by FTIR spectroscopy. The thermal oxidation of polyunsaturated fatty acids during heating was studied by the determination of unsaturation percentage and transisomers at various temperatures and heating times. Oils frequently used in food frying such as olive oil, sunflower oil, corn oil and seeds oil (sunflower, safflower and canola seed), and lard were studied. The Absorbance Correction Methodis proposed to correct the spectral interference and allows the analytic use of signal which would not be initially valid for quantitativeanalysis. The results show that there is a decrease in unsaturation and an increase in transisomers starting at 150°C and becomes more pronounced at temperatures around 250°C. This variation in unsaturation grade and conformation provides evidence of the transformation of essential polyunsaturated fatty acids and subsequent decrease in the oils’ nutritional value.

Two galactosyl derivatives of [DMet2,Pro5] enkephalin‐amide (compound 1), namely [DMet2,Pro5] enkephalin [N1.5‐beta‐D‐galactopyranosyl] amide (compound 2) and O1.5‐(beta‐D‐galactopyranosyl) [DMet2,Hyp5] enkephalin‐amide (compound 3) have been synthesized. Such glycosylpeptides have been shown to be extremely potent analgesic agonists. The conformational analysis of these three compounds in DMSO‐d6 solution has been carried out using two‐dimensional NMR methods. Both the parent compound (1) and the beta N‐galactosyl derivative (2) show similar NMR parameters which are consistent with fairly rigid beta‐strands at both the N‐terminus and C‐terminus, connected by a glycine residue that displays a mixture between multiple conformational states. Thus, although the beta N‐galactosyl derivative (2) has been shown to be significantly more potent than the parent compound (1) in the tail immersion and paw pressure tests of analgesia, no correlation can be established between the conformation of (1) and (2) in DMSO and the difference in analgesic activity. In contrast, important conformational differences with respect to (1) and (2) have been detected in the beta O‐galactosyl derivative (3). In this case, only one of the likely conformations for (1) and (2) are consistent with the experimental data. These data show that the position of the galactose residue in compound (3) causes Gly3 to loose flexibility leading to a more rigid folded conformation. Such a change in conformation could be related to the difference in analgesic activity between (2) and (3).

A semi-empirical model has been developed to quantify the interelemental effects in X-ray fluorescence analysis. The measured X-ray fluorescence intensity has been expressed as a function of the different fluorescence elements composing the sample. this complex function has become an operative function via a Taylor series development. An explication has been given for the significance of the different terms of the series. These terms respond to mathematical functions known as characteristic functions for each chemical system. A parameter (B) has been defined which makes it possible to quantify the influence of the interelemental effect as a function of the analyte concentration (C) and that of the concomitant elements. The proposed model has been applied to the Fe-Zr-diluent chemical system. Simple relationships between B vs C have been obtained independently considering iron or zirconium as analyte.

In this paper a method is proposed for the multielemental analysis of Sb(III), Ba, Cd, Cr(III), Hg, Pb and As(III) in plastics, using X-ray fluorescence after alkaline decomposition and preconcentration by (co)precipitation. The organic matrix is destroyed by decomposition with sodium hydroxide melted in a silver crucible by the open system technique, using sodium nitrate as auxiliary oxidant. The variables which influence preconcentration are optimized: digestion time, pH, salinity, carrier and sodium diethyldithiocarbamate (DDTC) and sodium rhodizonate (R) as precipitants. The calibration curves were linear up to 200 µg of the element present, except for lead (150 µg) antimony(III) (100 µg) and barium (1000 µg). The proposed method has been applied to several different industrial plastics. The procedure is quick and leads to results comparable with those obtained when using a recommended decomposition for each element separately.

The miscibility of phosphatidylserine, phosphatidylcholine, and cholesterol in monolayers were studied. The influence of sodium and calcium ions in this system was determined. The compression isotherms of mixed monolayers of the above cited three components spread on subphases containing opiate molecules are elucidated. Moreover, the penetration kinetics of opiate molecules in these mixed monolayers was also recorded. The results show that the presence of cholesterol always lowers the penetration of opioid molecules; this effect is weaken for meperidine, the most hydrophobic of the molecules assayed.

Summary: The H-Point Standard Additions Method (HPSAM) is proposed in order to resolve overlapping peaks in liquid chromatography by using a conventional fluorescence detector. The method uses as analytical signals the heights or the areas obtained at two previously selected emission wavelengths, and good results are obtained for highly overlapping peaks with highly overlapping fluorescence spectra. The principal benefits of the method are the ease of finding the required wavelengths, its insensitivity to changes in the retention time of the peak from one injection to another, and the possibility of using it in highly or only partially overlapping peaks. We have applied the method to the determination of phenol and cresols in water, resolving by the proposed method the overlapping peaks ofm- andp-cresol.

The influence of subphase composition and ionic strength on the interaction between opiate molecules and phosphatidylcholine has been studied. Results show that a neutral pH favours the penetration of opiate molecules in phosphatidylcholine monolayers, but the ionic strength and the chemical nature of buffer components affect also greatly these interactions. The results could explain, in part the differences in opioid binding values observed for different buffers.

Compression isotherms of mixed monolayers of phosphatidylcholine (PC) and sulphatides (S) were carried out, with the lipids being spread on subphases of different pH and different ionic composition. Several common trends can be observed. All monolayers when compressed reach collapse. Collapse pressures are directly related to the molar fractions of the lipids in the monolayer. Miscibility is not ideal, in general, and is independent on the surface pressure of the monolayer, the mixed monolayers being always (with some exceptions) in a more expanded state than those of the pure components. The thermodynamic parameters corresponding to the mixing interactions have been calculated at the molar composition that gives a maximum deviation from ideality.

The interaction between opiate molecules and phosphatidylserine (PS) or phosphatidylcholine (PC) has been studied on compression isotherms and penetration kinetics. Phosphatidylcholine-opiate interactions are weak and similar in magnitude for all opiate molecules. On contrary, PS and PS/PC interact strongly and differently with opiate molecules. The differences in penetration are not directly related to the pKa or hydrophobicity of the molecules.