Volume 92, Issue 3

Quality and reliability of analytical results are, in general, key issues for all laboratories but become a top priority for laboratories accredited according to ISO/IEC 17025:2005. In this international standard the proficiency testing (PT) is regarded as a means to assure the validity of results. Nowadays, the proved competence of laboratories is an essential requirement especially for that structures that are involved in the official controls aimed at ensuring the safety of EU food products and the public health. To guarantee the EU consumers, the Council and the Commission have designated 28 European Union Reference Laboratories (EURLs) for food and feed, whose main role is to contribute to the standardization of analytical methods and to the harmonization of performance among the EU National Reference Laboratories (NRLs) to reach a comparable level of quality in the analytical data among all Member States. With this aim, the organization of PTs is a task that each EURL has to accomplish. Over the last 15 years, the EURL for chemical elements in food of animal origin (EURL-CEFAO) have organized 32 PTs on determination of total As, Cd, Pb and total Hg in meat, milk, fish and offal for the benefit of its network of NRLs. Some specific aspects of this activity will be discussed (e.g. preparation and characterization of PT materials, statistical evaluation of data, follow-up actions). Finally, based on the EURL-CEFAO experience, it will be demonstrated that the participation into PTs on a regular basis can result in an improvement of the laboratory’s performance as well as in the harmonization of the results submitted by participants.

Biopolymer nanocomposites were prepared by solvent casting dispersing lauryl-functionalized cellulose nano-fibrils (CNF) in a poly(lactic acid) matrix (PLA). The release of residual chloroform (CHCl 3 ) solvent molecules was studied by Thermal Desorption Spectroscopy (TDS) analysis. TDS spectra of the PLA matrix show a single desorption peak at T P  = 393 K with FWHM ~10 K, compatible with a zero-order desorption kinetics. This narrow TDS peak was accurately reproduced assuming that: (i) the rate limiting step is given by the CHCl 3 de-trapping from sites in the PLA matrix where residual solvent molecules form small aggregates and (ii) the activation energy for desorption linearly decreases from 1.19 eV for saturated traps to 1.11 eV when the traps occupancy by solvent molecules approaches zero. The balance energy term ϵ D  = −0.08 eV is due to the attractive interactions between trapped CHCl 3 molecules. Adding CNF particles to the PLA matrix the zero-order peak shifts to lower temperatures and a second peak with FWHM ~60 K appears at higher temperatures. This second peak is compatible with a first-order desorption kinetics and is attributed to the release of dispersed CHCl 3 molecules from trapping sites in PLA-CNF interface region. The obtained information are of interest for applications in food and electronic packaging and for the development of medical materials.

The bystander effect (BE) is an important biological phenomenon that induces damages in distant and not directly affected by a chemical/physical stress cells. This effect, well known in ionizing radiation treatment, relies on reactive signals released by exposed cells and transmitted via cell–cell interaction or culture medium. In this study, cycloheximide (CHX)-induced apoptotic U937 cells and untreated THP-1 cells were chosen to investigate the chemical-induced BE. The effects of apoptotic U937 cells culture medium, Conditioned Medium (CM), on THP-1 cells were evaluated by morphological and immunohistochemical analysis performed by light microscopy; 1D 1 H and 2D J-resolved (JRES) NMR metabolomic analysis has been used to characterize the molecules involved in the BE. In summary, this study indicates that: CM of CHX-treated U937 cells induces a time-dependent induction of toxicity, probably apoptotic cell death, and macrophagic differentiation in THP-1 cells; CM contains different metabolites respect fresh culture medium; CM recruits in vivo activated fibroblasts, endothelial cells, macrophages and mononuclear inflammatory cells in rat calf muscles. These data suggest that CHX exposed cells could cause BE through the release, during the apoptotic process, of soluble factors into the medium that could be exploited in anticancer protocols.

This study reports the catalytic preparation, characterization, and evaluation of nanoscale core-shell structures with a γ-Fe 2 O 3 core covered by a SiO 2 monoshell or by a SiO 2 @TiO 2 multishell as a support for Pt nanoparticles (NPs) to synthesize active and operationally stable catalysts for selective liquid-phase cinnamaldehyde hydrogenation. The structures were designed with a magnetic core so they could be easily recovered from the catalytic bed by simple magnetization and with a SiO 2 monoshell or a SiO 2 @TiO 2 multishell to protect the magnetic core. At the same time, this study details the effect of the shell on the catalytic performance. Moreover, the effect of particle size on the selective production of cinnamyl alcohol was studied by preparing two families of catalysts with metal loadings of 1 wt% and 5 wt% Pt with respect to the core-shell. The particle size effect enabled the Fe 2 O 3 @SiO 2 -5%Pt system, with an average particle size of 5.6 nm, to reach 100 % conversion of cinnamaldehyde at 300 min of reaction, producing cinnamyl alcohol with 90 % selectivity; this result differed greatly from that of the Fe 2 O 3 @SiO 2 -1%Pt (d Pt  = 3.5 nm) system, which reached a maximum conversion at 600 min with 49 % selectivity for the product of interest. However, the Fe 2 O 3 @SiO 2 @TiO 2 -x%Pt systems showed lower levels of conversion and selectivity compared to those of the Fe 2 O 3 @SiO 2 -x%Pt catalysts, which is attributed to the fact that average metal particle sizes below 5.0 nm were obtained in both cases. After reduction in H 2 at 773 K, the Fe 2 O 3 @SiO 2 @TiO 2 -1%Pt catalyst showed deactivation, reaching 10 % conversion at 600 min of reaction and 60 % selectivity for the product of interest. However, the reduced Fe 2 O 3 @SiO 2 @TiO 2 -5%Pt system showed 98 % conversion with 95 % selectivity for cinnamyl alcohol at 24 h of operation; the increase in selectivity is attributed to the combined effects of the increase in average particle size (~7.5 nm) and the presence of strong metal-support interaction – SMSI – effects after reduction. Finally, the most selective systems were tested for operational stability, where the Fe 2 O 3 @SiO 2 @-5%Pt catalyst could be reused in three consecutive operating cycles while maintaining its activity and selectivity for cinnamyl alcohol – unlike the Fe 2 O 3 @SiO 2 @TiO 2- 5%Pt reduced system, which was deactivated after the third reaction cycle due to active phase leaching.

Calcium carbonate-based hollow or porous particles are one of the preferred carriers for fabrication of drug delivery systems. We have developed an eco-friendly method to produce calcium carbonate nanocrystals, which have shown biocompatibility and optimal capacity to across cell membrane in human cell lines providing new tools in cancer therapy. The success of drug delivery systems has paved the way for the development of systems for controlled release of agrochemicals. In this work, we exploited calcium carbonate nanocrystals as carriers for targeted release of phytodrugs investigating a potential control strategy for the pathogen Xylella fastidiosa. This pathogen is the causal agent of the Olive Quick Decline Syndrome that is an unprecedented emergency in Italy and potentially in the rest of Europe. We studied nanocrystals interactions with bacteria cells and the application in planta to verify olive plants uptake. Ultrastructural analysis by electron microscopy shown an alteration of bacteria wall following nanocrystals interaction. Nanocrystals were adsorbed from roots and they translocated in plants tissues. Calcium carbonate carriers were able to encapsulate efficiently two types of antimicrobial substances and the potential efficacy was tested in experiment under greenhouse conditions.

In this work, poly (vinylcaprolactam-co-itaconic acid) microgel was prepared by free radical polymerization. Silver nanoparticles were prepared in synthesized microgel networks by in situ reduction of Ag + ions, loaded in microgel from aqueous solution of AgNO 3 . The prepared microgel was characterized by Fourier transformation infra-red spectroscopy, UV-Visible spectroscopy, fluorescence spectroscopy, X-ray diffraction, laser light scattering, thermal gravimetric analysis, differential scanning calorimetry and transmission electron microscopy. Swelling behavior of microgel was studied as a function of temperature and pH. The microgel was found to be in swollen state at low temperature and basic medium while in collapsed state at high temperature and acidic medium. A slight decrease in swelling capacity of microgel was observed after the fabrication of silver nanoparticles. A decrease in the emission intensity and a red shift in surface plasmon resonance wavelength of silver nanoparticles was observed with pH induced swelling of microgel. Catalytic activity of the composite microgel was studied by using them as catalyst for the reduction of 4-nitrophenol, methyl orange and methylene blue. Effects of temperature and catalyst dose were also investigated. The reduction rates of 4-NP, MB and MO were found to be 0.859, 0.0528 and 0.167 min −1 , respectively. The change in catalytic performance and shift in absorption maxima and emission intensity of composite microgel as a function of temperature and pH reveals that this system has potential to be used as tunable catalyst and optical sensor.

In this work we used a combination of different techniques to investigate the adsorption properties of curcumin by zeolite type A for potential use as an anticancer drug carrier. Curcumin is a natural water-insoluble drug that has attracted great attention in recent years due to its potential anticancer effect in suppressing many types of cancers, while showing a synergistic antitumor effect with other anticancer agents. However, curcumin is poorly soluble in aqueous solutions leading to the application of high drug dosage in oral formulations. Zeolites, inorganic crystalline aluminosilicates with porous structure on the nano- and micro-scale and high internal surface area, can be useful as pharmaceutical carrier systems to encapsulate drugs with intrinsic low aqueous solubility and improve their dissolution. Here, we explore the use of zeolite type A for encapsulation of curcumin, and we investigate its surface properties and morphology, before and after loading of the anticancer agent, using scanning electron microscopy (SEM), powder X-ray diffraction (XRD), differential scanning calorimetry (DSC), and UV-vis spectroscopy. Results are used to assess the loading efficiency of zeolite type A towards curcumin and its structural stability after loading.

Electronic structure calculations have been performed to determine the thermochemistry and kinetics of the reaction between OH and the radicals of the S enantiomer of the herbicide Metolachlor, 2-chloro-N-(2-methyl-6-ethylphenyl)-N(2-methoxy-1-methylethyl) acetamide (MC), produced by photoinduced breaking of the C–Cl bond. Both density functional and ab initio composite methods were employed to calculate the structure of reactants, intermediates, transition states and products, in gas phase and in aqueous solution. The expected relative abundance of each product was calculated and compared to the experimentally observed concentrations. It is shown that a combination of thermodynamic and kinetic characteristics interplay to produce the expected theoretical abundances, which turn out to be in agreement with the experimentally observed distribution of products.

Liquids for electronic cigarettes and the vapor generated from them were examined by chemical and biological methods in order to reveal potential risk factors and their acceptability for consumers. Although the majority of the liquids on the market appear to be safe, some aroma compositions have been identified as possibly toxic for human vein epithelial cells, similar to tobacco smoke, thus indicating potential health risks and suggesting suitable test procedures before marketing the liquids.

The Hirao reaction, i.e. the P–C coupling between a bromoarene and a >P(O)H reagent performed in most cases in the presence of a Pd(0) complex incorporating a P -ligand may also be carried out applying a Ni(II) catalyst precursor with or without Zn or Mg as the reducing agent. The Ni catalysts may include P - or N -ligands. B3LYP/6-31G(d,p)//PCM(MeCN) quantum chemical calculations suggested that the mechanism of the NiX 2 catalyzed (X=Cl or Br) P–C couplings performed in the absence of a reducing agent, and in the excess of the >P(O)H reagent serving as the P -ligand (via its tautomeric >POH form) is completely different from that of the Pd(OAc) 2 promoted version, as no reduction of the Ni(II) occurs. In the two variations mentioned, the active catalyst is the dehydrobrominated species derived from primary complex [(HO)Y 2 P] 2 Ni(II)Br 2 , and the [(HO)Y 2 P] 2 Pd(0) complex itself, respectively. Both species undergo temporary oxidation (to “Ni(IV)” and “Pd(II)”, respectively) in the catalytic cycle. During the catalysis with “P 2 Ni(II)X 2 ”, one of the P -ligands serves the >P(O)H function of the ArP(O)H <  product. The consequence of this difference is that in the Ni(II)-catalyzed case, somewhat less >P(O)H-species is needed than in the Pd(0)-promoted instance. Applying 10 % of the Pd(OAc) 2 or NiX 2 precursor, the optimum quantity of the P -reagent is 1.3 equivalent and, in the first approach, 1.1 equivalent, respectively. Preparative experiments justified the new mechanism explored. The ligation of Ni(II) was also investigated by theoretical calculations. It was proved that the bis-complexation is the most favorable energetically as compared to the mono-, tri- and tetra-ligation.

The influence of doping of polyantimonic acid with vanadium ions on the ion exchange H + /Na + kinetics is determined. With the help of the X-ray analysis it is shown that doped compounds H 2 Sb 2- x V x O 6-δ  ·  n H 2 O, where x  = 0.14; 0.36; 0.48 have the pyrochlore-type structure. With the increase of the amount of vanadium in a sample there is a decrease of a unit cell parameter. It is determined that there is a reduction of a unit cell frame, formed by antimonic and vanadium ions, and a size reduction of hexagonal cavities, in which protons are located. It is shown that during the ion exchange of H + /Na + there is a change of the unit cell plane without a symmetry breaking of a crystal structure, which demonstrates solid solution formation. With the increase of the amount of vanadium in the sample there is a decrease of the ion-exchange capacity, which is connected with the decrease of the channel’s section size. The ion exchange H + /Na + kinetics has been studied with the approximation of the Boyd’s model for the intergrain diffusion. Diffusion coefficients had the order 10 −13 m 2 /s and decreased with the increase of the amount of vanadium in the sample.

Groups of electrons, radial with respect to the atomic nucleus and with the same value of the orbital quantum number and the same number on the subshell, are considered. A spin-orbital exclusion principle is established, regulating the spin value distribution on the subshells with the same value of the orbital number. According to this principle, all subshells are divided into positive and negative ones, depending on the direction of the spin of their first electron. It is found that, in the real sequence of the appearance of new subshells, a spin-orbital periodicity takes place, which develops in cycles consisting of two periods that are mirror-symmetric to each other in the direction of the spin of their electrons. Moreover, atomic number of any period is equal to the sum of the principal and orbital quantum numbers of its subshells, and this can serve as an explanation for the Madelung rule. It is demonstrated that Mendeleev’s chemical periodicity lags behind the spin-orbital periodicity by two elements and repeats its structure. From these positions, the absence of a pair in the first period of Mendeleev’s table and the pairing of all its other periods are explained. Based on the obtained results, an eight-period table of elements, the prototype of which being Janet’s left-step table, is compiled and briefly described.

This IUPAC Technical Report is one of a series that seeks to distil the essentials of IUPAC nomenclature recommendations. The present report provides a succinct summary of material presented in the publication Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 . The content of this report will be republished and disseminated as a four-sided lift-out document (see supplementary information) which will be available for inclusion in textbooks and similar publications.