Free-Radical Photopolymerization for Curing Products for Refinish Coatings Market.

Even though there are many photocurable compositions that are cured by cationic photopolymerization mechanisms, UV curing generally consists of the formation of cross-linking covalent bonds between a resin and monomers via a photoinitiated free radical polymerization reaction, obtaining a three-dimensional polymer network. One of its many applications is in the refinish coatings market, where putties, primers and clear coats can be cured faster and more efficiently than with traditional curing. All these products contain the same essential components, which are resin, monomers and photoinitiators, the latter being the source of free radicals. They may also include additives used to achieve a certain consistency, but always taking into account the avoidance of damage to the UV curing-for example, by removing light from the innermost layers. Surface curing also has its challenges since it can be easily inhibited by oxygen, although this can be solved by adding scavengers such as amines or thiols, able to react with the otherwise inactive peroxy radicals and continue the propagation of the polymerization reaction. In this review article, we cover a broad analysis from the organic point of view to the industrial applications of this line of research, with a wide current and future range of uses.

Population status of Boswellia papyrifera woodland and prioritizing its conservation interventions using multi-criteria decision model in northern Ethiopia.

Boswellia papyrifera woodland provides considerable economic, ecological and socio-cultural benefits in the drylands of Ethiopia. However, its populations are in rapid decline due to human pressure and environmental degradation. As a consequence, the species is now considered being endangered, demanding an urgent conservation intervention to sustain its existence. This study was carried out in the Abergele district, northern Ethiopia, with objectives to characterize the current population structure of B. papyrifera and prioritize its potential conservation intervention alternatives using Analytical Hierarchy Process (AHP) modelling techniques. The woody species related data were collected from 33 sample plots randomly established in the study area. Data related to the potential intervention alternatives and their evaluating criteria were collected from experts, personal experiences and intensive literature reviews, and then validated using stakeholders' focus group discussion. Four candidate alternatives were then considered for the AHP: 1) free grazing with no tapping resting period (FGNTR), 2) free grazing with a rotational tapping (FGRT), 3) area exclosure with medium tapping resting period (AEMTR), and 4) area exclosure with long tapping resting period (AELTR). The results showed that the population structure of B. papyrifera is unstable and is characterized by low density (266 trees ha-1), absence of regeneration and saplings (DBH<10 cm) due to different interrelated disturbances such as overgrazing, over tapping, pests, agricultural expansion and poor managements. The overall priority ranking value of all stakeholders using the AHP techniques also indicated that AEMTR (with overall rank value of 0.352) and AELTR (0.294) as the best alternatives strategies, respectively, for sustainable B. papyrifera woodland conservation. For the success of these strategies, their economic impacts at their early implementation stages (5-10 years) should be minimized by collecting different non-timber forest products from the woodland. Continuous capacity building training on sustainable utilizations and managements of B. papyrifera woodland should also be provided for all relevant stakeholders.

Structural Preferences in Phosphanylthiolato Platinum(II) Complexes.

The transition-metal complexes of heterotopic phosphanylthiolato ligands are useful in various reactions which depend on the stereochemistry of the complexes. Bis-chelate complex [Pt(SCH2CH2PPh2-κ(2) P,S)2] (1) was obtained in good yields by direct base-free substitution reaction of the corresponding phosphanylthiol (HSCH2CH2PPh2) with K2PtCl4 or by oxidative addition of the same phosphanylthiol to Pt(PPh3)4. In agreement with the antisymbiosis rule, complex 1 shows a cis-P,P arrangement in solid state crystallizing in the monoclinic system (C2/c). Density functional theory (DFT) calculations on 1 reveal the right characteristics for the preferred cis-P,P arrangement, rationalizing its formation. Direct base-free reaction of [PtCl2(1,5-cyclooctadiene)] with one equivalent of the same phosphanylthiol produce the trinuclear complex [PtCl(µ-SCH2CH2PPh2-κ(2) P,S)]3 (2) instead of the binuclear structure common in palladium and nickel derivatives. Crystals of 2 are triclinic (P 1‾ ) showing a sulfur-bridging edge-sharing cyclic trinuclear complex with square-planar coordination geometry around the platinum atoms and a Pt3S3 cycle in skew-boat conformation. This preference for the trinuclear structure was rationalized mechanistically and through conceptual DFT.

Structural Preferences in Phosphanylthiolato Platinum(II) Complexes.

Invited for this month's cover picture are the groups of Prof. Alfonso Polo and Dr. Albert Poater at the Universitat de Girona, as well as their collaborators from the Universitat Autònoma de Barcelona and the Institute of Chemical Research of Catalonia. The cover picture shows phosphanylthiolate ligand coordination on a platinum(II) center to give only the bischelate cis -P,P isomer when the ligand/Pt ratio is 2, whereas a trinuclear unexpected complex is achieved with a ligand/Pt ratio of 1. Here, the synthesis and structural determination is combined with density functional theory (DFT) calculations to rationalize the reaction mechanistically and through conceptual DFT. The exciting point of this study is that it opens the door to test new experimental pathways to monitor the preferred cis or trans arrangement of bidentate ligands to platinum. (Legend: H-white, C-black, P-purple, S-yellow, Cl-green, Pt-blue.) For more details, see the Full Paper on p. 51 ff.

Iodine nutritional status in pregnant women of two historically different iodine-deficient areas of Catalonia, Spain.

OBJECTIVE: Catalonia (Spain) has a historically worse situation of mild iodine deficiency in the Pyrenees Mountains compared with the coastal region. The aim of this study was to evaluate the current iodine status in pregnant women living in these two areas. METHODS: An epidemiologic prospective survey included 267 consecutive pregnancies in the Catalan mountains (n = 139) and coast (n = 128) studied during the first trimester; an additional subset of 135 women from the initial cohort was available for evaluation in the third trimester. Urinary iodine (UI) was measured, and questionnaires to determine iodized salt and sea fish consumption and potassium iodide supplementation were administered. RESULTS: The median UI in the first trimester was 163 µg/L for the entire cohort, with differences between mountain and coastal regions (209 versus 142 µg/L, P = 0.007). The highest prevalence of iodized salt consumption was in the mountain area (58% versus 36.4%, P < 0.001). For the entire group, a higher median UI was found in iodized salt consumers compared with non-consumers (193 versus 134 µg/L, P < 0.001). In the third trimester, an increase of median UI was seen in those to whom iodine supplements were given during pregnancy (190 versus 154 µg/L, P = 0.015). CONCLUSION: A reversal in the historically iodine-deficient situation was observed in the Catalan Pyrenees compared with the coastal area, with a globally acceptable iodine status in pregnant women of the two geographic locations. Iodized salt consumption seems to have contributed to maintaining an acceptable iodine status in this population.

Erupción de la dentición permanente en un grupo de 1,123 niños y niñas catalanes / Eruption of the permanent teeth in a group of 1,123 catalan children

Objetivo. Determinar las edades medias de erupción de los dientes permanentes de nuestra muestra. Método. Se han estudiado 605 niños y 518 niñas de raza blanca y de edades comprendidas entre los 5 y los 14 años, todos residentes en la población de Tona (Osona, Catalunya). Las exploraciones se realizaron en las tres escuelas que hay en la población, siguiendo el método transversal. Los datos recogidos fueron: nombre y apellidos del niño explorado, fecha de nacimiento, sexo, peso, talla y odontograma de dentición permanente. Las estimaciones de las edades medias de erupción de cada diente se calcularon aplicando el método de Kärber. Resultados. Después de validar la muestra en cuanto a tamaño, edad, peso y talla, confirmamos que nos encontrábamos frente a un grupo homogéneo e igual al resto de los niños catalanes. Presentamos las tablas de las edades medias de erupción para cada diente permanente en los dos maxilares, para ambos sexos. Conclusiones. Los datos de peso y talla de la muestra estudiada no presentan diferencias significativas con las que aportó De la Puente. Se han confeccionado, por primera vez, las tablas de las edades de erupción de todos los dientes permanentes (exceptuando los terceros molares) para una muestra de niños y niñas catalanes (AU)