A molecular single-electron transistor (SET) with (10-Boranylanthracene-9-yl)borane molecule as an island has been analyzed in an effort to model a better acene series SET. The ...(10-Boranylanthracene-9-yl)borane molecule was obtained through the substitution of dangling hydrogens of middle honeycomb by boron in anthracene. A first principle analysis has been performed to analyze the impact of boron substitution in anthracene and on the SET performance using density functional theory (DFT)-based ab initio tools Atomistix Toolkit-Virtual Nanolab and Gaussian03. To analyze the impact of boron substitution, different structural and electronic properties, such as electron density difference, natural bond orbital analysis, electron localization function, molecular energy spectrum, total energy, bond lengths, and bond angles, have been calculated, and to analyze the device performance, charging energies have been calculated and plotted total energies, charge stability diagram as a function of bias potentials. The analysis confirms that the proposed doped anthracene-based SET has high switching speed and power efficiency in comparison with the other organic molecular SETs reported of the kind.
Non‐planar fluorophores offer unique avenues of intra‐ and intermolecular energy transfer not available in their planar counterparts. We have rationally designed a molecular tweezer based on the ...pyridine‐2,6‐dicarboxamide framework having two structurally similar arms with extended π‐surface. We termed this molecular tweezer as Heli(aza)cene (HAC) due to its spontaneous adoption of helical conformation stabilized by the amide and imine moieties present in it. In the helical conformation, the two arms of HAC are twisted unequally. This asymmetry confers dissimilar electronic character to the two arms and results in intramolecular charge transfer interactions in HAC. Homochiral stacking of the P‐ and the M‐ helices in crystal, and profound redshifting of the emission at higher concentrations of HAC was attributed to intermolecular charge‐transfer interactions in aggregated/crystal state. Exposure of HAC, in solution as well as in the solid state, to Lewis/Brønsted acids results in rapid and vibrant color changes. This is the first example of a π‐layered helical molecule exhibiting tunable intra‐/intermolecular charge‐transfer characteristics.
A helical molecular tweezer that shows tunable intra‐ and intermolecular charge transfer properties and profound visual changes, both in solution as well as the solid state, through exposure to Lewis/Brønsted acids, is reported.
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•The systematics and biogeography of the genus Bleda, endemic to Afro-tropical forests.•We date the earliest divergence to the Miocene, with a west to east diversification ...pattern.•Intra-specific divergence events date to the Pliocene and Pleistocene epochs.•We recover geographically-structured lineages in three species within lowland forest blocks.•Plio–Pleistocene forest refuges and river barriers as potential drivers of diversity patterns.
Recent investigations of distributional patterns of Afro-tropical lowland forest species have demonstrated to some degree our overall lack of understanding involving historical diversification patterns. Traditionally, researchers have relied upon two hypotheses, each of which views the lowland forest of Africa in differing roles. The Pleistocene Forest Refuge Hypothesis (PFRH) posits that biogeographic patterns of avian lowland species are explained via allopatric speciation during forest fragmentation cycles in the Pleistocene epoch (c. 1.8Ma–11,700Ka). The Montane Speciation Hypothesis (MSH) countered by suggesting that lowland forests are “evolutionary museums” where species, which originally evolved in montane forest refuge centers, remained without further diversification. Furthermore, investigations have largely regarded widespread, avian species which lack phenotypic variability as biogeographically “uninformative”, with regards to historical biogeographic patterns. To test the tenets of these ideas, we investigated the systematics and biogeography of the genus Bleda, whose constituent species are restricted to lowland forest and are lacking in phenotypic variation. Using extracted DNA from 179 individuals, we amplified two mitochondrial genes and three nuclear loci and utilized Bayesian phylogenetic methods and molecular clock dating to develop a time-calibrated phylogeny of Bleda. We used LaGrange to develop an ancestral area reconstruction for the genus. Haplotype networks for three species were generated using Network. We recovered the four currently recognized species of Bleda, plus a monophyletic B. ugandae, a current sub-species which may warrant full species status. We found that the origins of the genus Bleda are estimated to be in the Upper Guinean forests of West Africa, dating to the Miocene (c. 7.5Ma), while the speciation events for the rest of the genus are dated to the Pliocene (c. 5–1.8Ma). Our analyses recovered discrete and highly differentiated geographic structuring of genetic diversity in West and Central Africa in three of five species, with many of the diversification events dating to the Pleistocene. The biogeographic patterns observed in Bleda can be explained through a combination of isolation via forest refuges during the Plio–Pleistocene and riverine barriers limiting secondary contact after forest expansion. We find evidence for the PFRH as a driver of intra-specific diversity, but conclude that it does not facilitate an explanation for speciation in the genus Bleda. The “evolutionary museum” concept furnished by the MSH is countered by our evidence of in situ diversification in the lowland forests of Africa. Additionally, our results provide strong evidence of the value of seemingly “uninformative” widespread avian taxa for revealing complex patterns of forest diversity. Overall, our study highlights that past researchers have both underestimated the amount of diversity found in lowland forests and failed to understand the complexity of historical forces shaping that diversity. Gaining a better understanding of lowland forest diversity and the historical factors which have shaped it will crucial in determining conservation tactics in the near future.
Celem artykułu jest analiza żydowskiej Biblii dla kobiet (na przykładzie pierwszych rozdziałów księgi Bereszit) i wskazanie na egalitarny charakter dzieła. Napisano je w jidysz, a więc języku ...codziennym wschodnich Żydów. Tekst przeznaczony był do użytku kobiet i mężczyzn – zwłaszcza tych nie znających hebrajskiego. Stanowi kompilacje tekstów biblijnych, komentarzy rabinicznych oraz legend i podań ludowych, wyjaśniających zagadnienia religijne oraz zwyczaje w na tyle prosty sposób, by mogły być zrozumiałe przez osoby niewykształcone w prawie mojżeszowym.
Aquesta introducció presenta les principals aportacions de les dues parts que configuren la secció especial titulada «Pensar a través de la ruïna: aproximacions teòriques i empíriques a les ruïnes de ...l’antropocè». L’objectiu d’aquesta secció especial és submergir-se des d’una perspectiva interdisciplinària en l’exploració i estudi de les ruïnes antropogèniques del nostre passat recent en un context de reptes i amenaces ambientals. Els articles compilats il·lustren la importància d’examinar aquestes ruïnes, destacant la seva riquesa així com la seva naturalesa complexa, frag-mentària i paradoxal. Així mateix, la present introducció subratlla les interseccions fèrtils entre els articles i ressegueix els diferents elements que conflueixen en l’abordatge de la crisi ecològica a través de la perspectiva de les ruïnes i els processos de ruïna.
This introduction aims to present the main contributions of the two parts of the special section – titled “Thinking through ruination: theore-tical and empirical approaches to the ruins of the Anthropocene”. The focus of this special section is to explore the anthropogenic ruins of our recent past within the current context of environmental challenges and threats. The compiled articles exemplify the significance of exa-mining these ruins, highlighting their richness and cross-disciplinary nature. Additionally, the introduction underscores the fertile intersections between the articles and discusses their common motifs in addressing the ecological crisis through the lens of ruins and ruination processes.
Esta introducción presenta las principales aportaciones de las dos partes de la sección especial titulada «Pensar a través de la ruina: aproximaciones teóricas y empíricas a las ruinas del Antropoceno». El objetivo de esta sección especial es sumergirse desde una perspectiva interdisciplinaria en la exploración y estudio de las ruinas antropogénicas de nuestro pasado reciente en un contexto de retos y amenazas ambientales. Los artículos compilados ilustran la importancia de examinar estas ruinas, destacando su riqueza así como su naturaleza compleja, fragmentaria y paradójica. Así mismo, esta introducción subraya las intersecciones fértiles entre los artículos y resigue los diferentes elementos que confluyen en el abordaje de la crisis ecológica a través de la perspectiva de las ruinas y los procesos de ruina.
Transfer prices are prices determined in the purchase and selling transactions between business segments or divisions within a company. Tax aspect and the management aspect of transfer prices are ...usually considered in the literature and praxis. Research in this paper is focused on the relation between the degree of autonomy of divisional managers by making decisions and the way of determining transfer prices in selling and purchase transactions between divisions of a company.The aim of this paper is to introduce problem of transfer pricingand to explain how decentralized decision makingthrough the transfer pricing system affectsshort-run and long-run divisional and corporate performances. Research has been carried out on a small sample of multidivisional companies that operate in Serbia. The main hypothesis is not confirmed, unlike similar results of researches carried out earlierin developed economies.Spearman's rank correlation coefficient and Phi coefficient are used in this research, as well as nonparametric Mann Whitney test.
Heuningneskrans was briefly excavated in 1968 by Peter Beaumont who exposed a 6.35 m deep archaeological sequence. However, as with other sites in the former Transvaal Province, Heuningneskrans has ...since played a minimal role in subsequent Stone Age research. The site was drawn to our attention while elaborating our research programme at Bushman Rock Shelter (BRS). The sites are approximately 4 km from each other and located in the Ohrigstad Valley, near the Blyde River catchment. This area, on the eastern margin of the Great Escarpment, connects the interior plateau of southern Africa (Highveld) with the Lowveld and the Mozambican coastal plain. In 2018, we reopened Heuningneskrans to expose and sample the profiles, contextualise Beaumont’s data, evaluate the site’s potential, and its complementarity with BRS. The excavation exposed a finely stratified sequence illustrating the action of various sedimentary agents. The last use of the site is associated with Iron Age groups, but most of the sequence documents human occupations that predate 27 000 cal. BP, and last until 8000 cal. BP (calibration OxCal 4.3 SHCal 13). The results of this first excavation campaign, together with ongoing investigations at BRS, highlight that this area is instrumental for the study of Middle and Later Stone Age developments in southern Africa.
Phylogenetic analysis of protocadherin genes identified a new gene subfamily, the delta-protocadherins, containing several conserved motifs in their cytoplasmic domains. This subfamily can be further ...subdivided into two subgroups, named delta1-protocadherins (comprising protocadherin-1, -7, -9, and -11 or X/Y) and delta2-protocadherins (comprising protocadherin-8, -10, -17, -18, and -19). The members of the delta1-protocadherin subgroup were analyzed in greater detail here. They share a similar gene structure that results in the expression of multiple alternative transcripts. All members of this subgroup have at least one transcript that contains a binding site for protein phosphatase-1alpha. Like most classic cadherins, each of three delta1-protocadherins analyzed in this study by in situ hybridization showed a unique expression pattern that differed from the patterns of the other delta1-protocadherins. Together, these results suggest that the members of the delta1-protocadherin subgroup exercise tightly regulated functions in the development, regionalization, and functional differentiation of the mouse brain.
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