Flowers are essential to maintain high beetle diversity (Coleoptera) in a Neotropical rainforest canopy

Many hypotheses have been proposed to explain the megadiversity of angiosperms and insects. Flowers and their pollinators represent the most common terrestrial mutualistic interaction today and this is thought to have driven the evolution of angiosperms and their visitors. Within the framework of that interaction, this paper develops and tests two new hypotheses: 1) megadiversity of canopy beetles in tropical rainforests is largely based on flower resources, and 2) the majority of adult canopy beetles are adapted to visit flowers. To test hypothesis 1, the beetle fauna associated with 23 canopy tree species (13 families, 45 individuals) in a 1.4 ha canopy plot of pristine lowland tropical rainforest in southern Venezuela was studied over one year. In total, 6698 adult beetles were collected and identified to 859 species in 44 families. Of these 859 species, 647 species (75.3%) were found with at least one individual on flowering trees, and 527 species (61.4%) were associated exclusively with flowering trees. The proportion of beetle species visiting exclusively small white flowers of the morphological generalist syndrome amounts to 36.6% of the entire canopy beetle community. Based on these findings, the second hypothesis was formulated that canopy beetles are specially adapted flower visitors. To test hypothesis 2, a sub-set study was conducted of the beetles visiting flowers of one tree species in the canopy plot, Hymenopus heteromorphus (Benth.) Sothers and Prance (Chrysobalanaceae). This is a mass-flowering tree with white flowers of a generalized morphology. A total of 440 adult beetles were collected in 20 days and identified to 138 species in 54 genera in 23 families. This assemblage was restricted to the flowering season of this tree. Data collected for H. heteromorphus and other mass-flowering tree species in the same plot indicates that a particular combination of flowering characteristics – massively flowering, white color, and generalized morphology – attracts the highest diversity of beetles. These findings together suggest that the enormous diversity of canopy beetles in Amazonian tropical rainforests is due mainly to flowers and that mass-flowering trees with small white flowers of the generalist syndrome play a particularly crucial role in assembly and nourishment of this megadiverse beetle community

Cross-sectional TEM preparation of hybrid inorganic/organic materials systems by ultramicrotomy

Preparation of hybrid inorganic-organic systems (HIOS) for transmission electron microscopy (TEM) in cross sectional view is the key for understanding the interfacial structure. Strikingly different materials properties like hardness, cleavability and heat sensitivity limit the number of applicable preparation strategies. Successful preparation of a HIOS system combining ZnO and para-sexiphenyl (6P) is realized by ultramicrotomy. It is shown that the alignment of the cutting plane with respect to the (0001) cleavage plane of ZnO plays a decisive role for successful preparation of extended TEM lamellae and the preservation of the HIOS structure. In particular, for (0001) oriented ZnO substrates the optimum cut direction is parallel to the HIOS interface. In cross-sectional high-resolution TEM images (100) lattice planes of 6P are observed proving the appropriate preparation strategy.Peer Reviewe

On the existence of a paramagnetic adduct of Ni(II)-bis-(di-n-butyl-diselenocarbamate). An EPR study

Paramagnetic adduct formation of pyridine with nickel(II)-bis(di-n-butyl-diselenocarbamate) is observed by means of EPR at 27°K. The low value of the zero field splitting and the g-factor are explained by strong spin-orbit interactions and by high covalency typical of the Se4-coordination sphere. © 1973

Spin-lattice relaxation of exchange-coupled Cu2+-Cu2+ pairs and single Cu2+ ions in crystals of zinc (II) bis(diethyl-dithiocarbamate)

Detailed investigations of the spin-lattice relaxation of single Cu 2+ ions and Cu2+-Cu2+ pairs in zinc (II) bis(di- ethyl-dithiocarbamate) single crystals are reported. The measurements were made in the temperature range 1.5<T<35K at v=28.8 and 9.0 GHz using the pulse saturation and the spin-echo method, respectively. At T<5K the single-ion relaxation is defined by direct processes; at higher temperatures two-phonon Raman processes were observed. In the range 4<T<12K the data can be fitted by an Orbach-Aminov process. A calculation of the single-ion relaxation rate for the direct process has been made. Also the pair relaxation rate in the same range was calculated considering the rate equations of the populations of the triplet state. From the temperature dependence of the Orbach-Aminov process the isotropic exchange integral was derived. Low-temperature EPR measurements provided the signs of the D-tensor and of the exchange integral. From the temperature dependence of the single-ion Raman relaxation rate the Debye temperature of the host crystal was estimated. For exchange coupled pairs the anomalous frequency dependence of T1 -1 was observed

Origin of a-plane (Al,Ga)N formation on patterned c-plane AIN/sapphire templates

a-plane (Al,Ga)N layers can be grown on patterned c-plane AlN/sapphire templates with a ridge direction along [1bar 100]Al2O3. Scanning nanobeam diffraction reveals that the formation of a-plane layers can be explained by nucleation of c-plane (Al,Ga)N with [11bar 20](Al,Ga)N[0001]Al2O3 at the ridge sidewalls. Faster growth of the top (11bar 20)(Al,Ga)N facet in the vertical direction leads to the overgrowth of c-plane (Al,Ga)N nucleated on the horizontal ridge and trench surfaces. Phase separation into binary GaN and AlN takes place during the first growth stages. However, this fades out and does not influence the composition of the final thick a-plane (Al,Ga)N layer

Case Report: Ocular Toxocariasis: A Report of Three Cases from the Mississippi Delta

Ocular toxocariasis can be vision threatening, and is commonly reported from tropical or subtropical regions. Knowledge of clinical manifestations from the United States, particularly in underserved areas such as the American South, is lacking. We report three cases of ocular toxocariasis in individuals from the Mississippi Delta, a rural community with prevalent poverty. Visual acuity was severely affected in two of the three cases. Increased awareness of ocular toxocariasis, which may have under-recognized frequency, will contribute to prompt diagnosis and treatment, which will ultimately improve patient health in the region

Ordered structure of FeGe₂ formed during solid-phase epitaxy

Fe3Si/Ge(Fe,Si)/Fe3Si thin-film stacks were grown by a combination of molecular beam epitaxy and solid-phase epitaxy (Ge on Fe3Si). The stacks were analyzed using electron microscopy, electron diffraction, and synchrotron x-ray diffraction. The Ge(Fe,Si) films crystallize in the well-oriented, layered tetragonal structure FeGe2 with space group P4mm. This kind of structure does not exist as a bulk material and is stabilized by the solid-phase epitaxy of Ge on Fe3Si. We interpret this as an ordering phenomenon induced by minimization of the elastic energy of the epitaxial film

Photochemistry of Furyl- and Thienyldiazomethanes: Spectroscopic Characterization of Triplet 3-Thienylcarbene

Photolysis (λ \u3e 543 nm) of 3-thienyldiazomethane (1), matrix isolated in Ar or N2 at 10 K, yields triplet 3-thienylcarbene (13) and α-thial-methylenecyclopropene (9). Carbene 13 was characterized by IR, UV/vis, and EPR spectroscopy. The conformational isomers of 3-thienylcarbene (s-E and s-Z) exhibit an unusually large difference in zero-field splitting parameters in the triplet EPR spectrum (|D/hc| = 0.508 cm–1, |E/hc| = 0.0554 cm–1; |D/hc| = 0.579 cm–1, |E/hc| = 0.0315 cm–1). Natural Bond Orbital (NBO) calculations reveal substantially differing spin densities in the 3-thienyl ring at the positions adjacent to the carbene center, which is one factor contributing to the large difference in D values. NBO calculations also reveal a stabilizing interaction between the sp orbital of the carbene carbon in the s-Z rotamer of 13 and the antibonding σ orbital between sulfur and the neighboring carbon—an interaction that is not observed in the s-E rotamer of 13. In contrast to the EPR spectra, the electronic absorption spectra of the rotamers of triplet 3-thienylcarbene (13) are indistinguishable under our experimental conditions. The carbene exhibits a weak electronic absorption in the visible spectrum (λmax = 467 nm) that is characteristic of triplet arylcarbenes. Although studies of 2-thienyldiazomethane (2), 3-furyldiazomethane (3), or 2-furyldiazomethane (4) provided further insight into the photochemical interconversions among C5H4S or C5H4O isomers, these studies did not lead to the spectroscopic detection of the corresponding triplet carbenes (2-thienylcarbene (11), 3-furylcarbene (23), or 2-furylcarbene (22), respectively)