Investigation of the long effective conjugation length in defect-free insulated molecular wires

Due to the “insulation” of the π-conjugated backbones, insulated molecular wires (IMWs) are expected to be applied to various optoelectronic applications and nanotechnology.[1] Recently, Kazunori et al have succeeded in the synthesis of a self-threading polythiophene with a polyrotaxane-like 3D architecture (PSTB, see Figure 1), for which an intrawire hole mobility of 0.9 cm2 V−1 s−1 has been measured.[2] Here, we aim to evaluate the extent of π-conjugation along polythiophene backbones sheathed within defect-free “insulating” layers. A comparison between the experimental Raman spectra of the self-threading oligomers (i.e. 2STB-5STB) and the corresponding PSTB polymer indicates that: (i) the ratio of relative intensities of the two most intense Raman bands (I1375/1445) increases with the elongation of the size chain but does not saturate up to the pentamer, and (ii) π-conjugation spreads over 17–18 thiophene units in the polymer. Whether the effective conjugation length of the polymer is better described by using the long oligomer extrapolation approach[3] or periodic DFT calculations of the polymer is discussed in detailed by exploiting the very recent potentialities of state-of-the-art quantum chemical simulations of vibrational properties for crystalline solids.[Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Sediments: sink, archive, and source of contaminants

Se ha publicado una corrección de este artículo el 03 February 2023 ; DOI: 10.1007/s11356-023-25555-y Publicado en: Environmental Science and Pollution Research, Vol. 30, nº 12, March 2023, pp. 35514Sediments are sources and sinks of contaminants and play an important role in mediating pollutants across environmental compartments of terrestrial and aquatic ecosystems. In surface waters (lakes, slowly flowing or dammed rivers, estuaries, oceans), organic and inorganic contaminants are either dissolved or sorbed to suspended matter and sediment particles according to their chemical properties. In the case of strong sorption, settling of suspended particles and sediment formation scavenge contaminants out of the water phase, resulting in the accumulation of contaminants in the beds of rivers and lakes.5 página

Black anglerfish (Lophius budegassa): weight-length relationships, weight conversion factors and condition factor trends from a decade of two stocks, in ICES Div. VIIIc-IXa (northern Iberian Atlantic waters) and in Div. VIIb,c,h,j,k (Celtic Sea, south-western Ireland and Porcupine Bank)

Weight-length relationships, weight conversion factors and condition factor are presented from a decade (2006 to 2015) for both stocks of black anglerfish (Lophius budegassa) in northern Iberian Atlantic waters (ICES Div. VIIIc-IXa) and in Celtic Sea, south-western Ireland and Porcupine Bank (ICES Div. VIIb,c,h,j,k). A total of 2035 and 1263 specimens were sampled respectively in each stock from commercial landings and research surveys. Total length [Lt (cm)], total weight [Wt (g)], “commercial” weight (gutted with liver) [Wgl (g)] and “scientific” weight (gutted without liver) [Wg (g)] were obtained. The weight-length relationships for the combined sexes were: Lt = 0.020 Wt2.916; Lt = 0.017 Wgl2.929; Lt = 0.017 Wg2.922 in Div. VIIIc-IXa, and Lt = 0.025 Wt2.841; Lt = 0.013 Wgl2.984; Lt = 0.013 Wg2.971 in Div. VIIb,c,h,j,k. The conversion factors (total weight - gutted weight), useful in fisheries management due to the commercial landings of this species are available in gutted weight, were: Wt = 1.186 Wgl; Wt = 1.236 Wg in Div. VIIIc-IXa, and Wt = 1.187 Wgl; Wt = 1.233 Wg in Div. VIIb,c,h,j,k. These updated values can be used in the process of the annual assessment of the state of both stocks in the ICES working group. The evolution of the condition factor over the year, indicator of nutritional status evolution, is also estimated for immature and mature individuals of each sex, showing some seasonal variation. The results are similar to the previously estimated in other studies