N-(4,5-Diaza-9H-fluoren-9-yl­idene)-4-meth­oxy­aniline

In the title compound, C18H13N3O, the diaza­fluorene ring system is almost coplanar (r.m.s. deviation = 0.0640 Å) and subtends an angle of 61.5 (4)° with the plane of the meth­oxy-substituted benzene ring. In the crystal structure, pairs of C—H⋯O hydrogen bonds link mol­ecules into centrosymmetric dimers parallel to the ab plane. Mol­ecules are also stacked in an obverse fashion along the c axis by a variety of π–π inter­actions with centroid–centroid distances in the range 3.557 (2)–3.921 (2) Å

Path integral solution for an angle-dependent anharmonic oscillator

We have given a straightforward method to solve the problem of noncentral anharmonic oscillator in three dimensions. The relative propagator is presented by means of path integrals in spherical coordinates. By making an adequate change of time we were able to separate the angular motion from the radial one. The relative propagator is then exactly calculated. The energy spectrum and the corresponding wave functions are obtained.Comment: Corrected typos and mistakes, To appear in Communications in Theoretical Physic

Bunyavirus requirement for endosomal K+ reveals new roles of cellular ion channels during infection

In order to multiply and cause disease a virus must transport its genome from outside the cell into the cytosol, most commonly achieved through the endocytic network. Endosomes transport virus particles to specific cellular destinations and viruses exploit the changing environment of maturing endocytic vesicles as triggers to mediate genome release. Previously we demonstrated that several bunyaviruses, which comprise the largest family of negative sense RNA viruses, require the activity of cellular potassium (K+) channels to cause productive infection. Specifically, we demonstrated a surprising role for K+ channels during virus endosomal trafficking. In this study, we have used the prototype bunyavirus, Bunyamwera virus (BUNV), as a tool to understand why K+ channels are required for progression of these viruses through the endocytic network. We report three major findings: First, the production of a dual fluorescently labelled bunyavirus to visualize virus trafficking in live cells. Second, we show that BUNV traffics through endosomes containing high [K+] and that these K+ ions influence the infectivity of virions. Third, we show that K+ channel inhibition can alter the distribution of K+ across the endosomal system and arrest virus trafficking in endosomes. These data suggest high endosomal [K+] is a critical cue that is required for virus infection, and is controlled by cellular K+ channels resident within the endosome network. This highlights cellular K+ channels as druggable targets to impede virus entry, infection and disease

Severe effects of long-term drought on calcareous grassland seed banks

Climate change models project shifts in precipitation patterns at regional and global scales. Increases in dry areas and the occurrence of drought predicted in future scenarios are likely to threaten grassland ecosystems. Calcareous grassland seed banks have proven to be resistant to short-term drought, but their responses to long-term drought are unknown. Here we show that 14 years of summer drought changed calcareous grassland seed bank composition, reducing its size and richness, and that these responses do not simply reflect patterns in the above-ground vegetation. Moreover, the effect of drought was larger on seed banks than on vegetation, and above-ground responses mediated by soil depth were less evident in the seed bank than in the vegetation. These results demonstrate that the severity of drought effects on calcareous grasslands is larger than previously thought, and show that this ecosystem is highly vulnerable and has low resilience to predicted decreases in soil moisture

Chemical Fixation of Carbon Dioxide Using a Green and Efficient Catalytic System Based on Sugarcane BagasseAn Agricultural Waste

In this study, an efficient, reusable, and environmental catalytic system consisting of sugarcane bagasse (an agricultural and sugar mill waste material, SCB) and KI was applied to the cycloaddition of carbon dioxide (CO₂) to epoxides or aziridines under mild conditions for the first time. Their catalytic cycloaddition activities were found to be well correlated with the large quantities hydroxyl groups in SCB, which had a synergetic effect with the halide anion of KI. The as-prepared catalytic system also exhibited excellent cycloaddition activities for various epoxide or aziridine substrates as well. Moreover, the catalyst could be recovered and reused multiple times without obvious loss in activity. The present method represents an integrated and ideal green process for the utilization of biomass and “carbon neutral” resources, which has a high potential for large-scale fixation of CO₂ into value-added chemicals