Symposium for Miroslav Hroch

Twelve historians and social scientists reflect on Miroslav Hroch's contributions to the field of nationalism studies. There are essays on his pioneering comparative historical studies of ‘small nation’ national movements and his distinction between nationalism and national movements. Other essays focus on concepts such as those of protagonist, the three phases of national movements, the small nation and nationally relevant conflict of interest. A further set of essays explores how Hroch's approach can be extended beyond small nations, beyond Europe and into the contemporary period.Political Culture and National Identit

A low-spin Fe(iii) complex with 100-ps ligand-to-metal charge transfer photoluminescence

Transition-metal complexes are used as photosensitizers1, in light-emitting diodes, for biosensing and in photocatalysis2. A key feature in these applications is excitation from the ground state to a charge-transfer state3,4; the long charge-transfer-state lifetimes typical for complexes of ruthenium5 and other precious metals are often essential to ensure high performance. There is much interest in replacing these scarce elements with Earth-abundant metals, with iron6 and copper7 being particularly attractive owing to their low cost and non-toxicity. But despite the exploration of innovative molecular designs6,8,9,10, it remains a formidable scientific challenge11 to access Earth-abundant transition-metal complexes with long-lived charge-transfer excited states. No known iron complexes are considered12 photoluminescent at room temperature, and their rapid excited-state deactivation precludes their use as photosensitizers13,14,15. Here we present the iron complex [Fe(btz)3]3+ (where btz is 3,3′-dimethyl-1,1′-bis(p-tolyl)-4,4′-bis(1,2,3-triazol-5-ylidene)), and show that the superior σ-donor and π-acceptor electron properties of the ligand stabilize the excited state sufficiently to realize a long charge-transfer lifetime of 100 picoseconds (ps) and room-temperature photoluminescence. This species is a low-spin Fe(iii) d5 complex, and emission occurs from a long-lived doublet ligand-to-metal charge-transfer (2LMCT) state that is rarely seen for transition-metal complexes4,16,17. The absence of intersystem crossing, which often gives rise to large excited-state energy losses in transition-metal complexes, enables the observation of spin-allowed emission directly to the ground state and could be exploited as an increased driving force in photochemical reactions on surfaces. These findings suggest that appropriate design strategies can deliver new iron-based materials for use as light emitters and photosensitizers

Unveiling cryptic species of the bumblebee subgenus Bombus s. str. worldwide with COI barcodes (Hymenoptera: Apidae)

Bumblebees of the subgenus Bombus s. str. dominate (or used to dominate) many north temperate pollinator assemblages and include most of the commercial bumblebee pollinator species. Several species are now in serious decline, so conservationists need to know precisely which ones are involved. The problem is that many Bombus s. str. species are cryptic, so that species identification from morphology may be impossible for some individuals and is frequently misleading according to recent molecular studies. This is the first review of the entire subgenus to: (1) avoid fixed a priori assumptions concerning the limits of the problematic species; and (2) sample multiple sites from across the entire geographic ranges of all of the principal named taxa worldwide; and (3) fit an explicit model for how characters change within an evolutionary framework; and (4) apply explicit and consistent criteria within this evolutionary framework for recognising species. We analyse easily-obtained DNA (COI-barcode) data for 559 sequences from 279 localities in 33 countries using general mixed Yule-coalescent (GMYC) models, assuming only the morphologically distinctive species B. affinis Cresson, B. franklini (Frison), B. ignitus Smith and B. tunicatus Smith, and then recognise other comparable COI-barcode groups as putative species. These species correspond to modified concepts of the taxa B. cryptarum (Fabricius), B. hypocrita Pérez, B. jacobsoni Skorikov, B. lantschouensis Vogt n. stat., B. longipennis Friese, B. lucorum (Linnaeus), B. magnus Vogt, B. minshanensis Bischoff n. stat., B. occidentalis Greene, B. patagiatus Nylander, B. sporadicus Nylander, B. terrestris (Linnaeus) and B. terricola Kirby (a total of 17 species). Seven lectotypes are designated. Our results allow us for the first time to diagnose all of the putative species throughout their global ranges and to map the extent of these geographic ranges