8,129 research outputs found
Fig. 38 in The genus Alexeter Förster (Hymenoptera, Ichneumonidae) in China, with descriptions of three new species
No full textFig. 38. Alexeter zangicus Sheng, Sun & Li, 2020, holotype, ♀ (GSFGPM), habitus, lateral view. Scale bar: 1 mm.Published as part of T., Li & S.P., Sun, 2022, The genus Alexeter Förster (Hymenoptera, Ichneumonidae) in China, with descriptions of three new species, pp. 81-103 in European Journal of Taxonomy 789 (81) on page 101, DOI: 10.5852/ejt.2022.789.1633, http://zenodo.org/record/590636
Fig. 37. Alexeter shakojiensis Uchida, 1930 in The genus Alexeter Förster (Hymenoptera, Ichneumonidae) in China, with descriptions of three new species
No full textFig. 37. Alexeter shakojiensis Uchida, 1930, ♀ (GSFGPM), habitus, lateral view. Scale bar: 2 mm.Published as part of T., Li & S.P., Sun, 2022, The genus Alexeter Förster (Hymenoptera, Ichneumonidae) in China, with descriptions of three new species, pp. 81-103 in European Journal of Taxonomy 789 (81) on page 100, DOI: 10.5852/ejt.2022.789.1633, http://zenodo.org/record/590636
Low-energy intergranular fracture in Al-Li alloys
No full textAn age-hardened Al–Li–Cu–Mg–Zr alloy (AA8090) used for a substantial part of the structure of a helicopter (in order to save weight) exhibited low-energy intergranular fracture during accidents, resulting in extensive damage. With this experience in mind, various hypotheses for brittle intergranular fracture in Al–Li alloys are reviewed, and possible remedial measures outlined. The effects of variables such as alloy composition, ageing times and temperatures, crystallographic texture, and test temperature on brittle-intergranular-fracture resistance are described, and it is concluded that lithium segregation to grain boundaries is primarily responsible for brittle intergranular fracture. Lithium segregation occurs mainly during the primary ageing treatment; but secondary ageing during service, where temperatures can reach 50–80°C, could increase lithium segregation and further increase susceptibility to brittle intergranular fracture. The evidence also suggests that the prevalence of a planar-slip-mode in Al–Li alloys, resulting in dislocation pile-ups at grain boundaries, is not responsible for brittle intergranular fracture, contrary to widespread opinion
Figs 1–3 in The genus Alexeter Förster (Hymenoptera, Ichneumonidae) in China, with descriptions of three new species
No full textFigs 1–3. Alexeter flavicoxa sp. nov., holotype, ♀ (GSFGPM). 1. Habitus, lateral view. 2. Head, anterior view. 3. Head, dorsal view. Scale bars: 1 = 2 mm; 2 = 0.2 mm; 3 = 0.1 mm.Published as part of T., Li & S.P., Sun, 2022, The genus Alexeter Förster (Hymenoptera, Ichneumonidae) in China, with descriptions of three new species, pp. 81-103 in European Journal of Taxonomy 789 (81) on page 85, DOI: 10.5852/ejt.2022.789.1633, http://zenodo.org/record/590636
Figs 15–20 in The genus Alexeter Förster (Hymenoptera, Ichneumonidae) in China, with descriptions of three new species
No full textFigs 15–20. Alexeter flaviventris sp. nov., holotype, ♀ (GSFGPM). 15. Head, lateral view. 16. Pronotum, anterior view. 17. Mesoscutum and scutellum, dorsal view. 18. Mesosoma, lateral view. 19. Wings. 20. Propodeum, dorsal view. Scale bars: 15–18, 20 = 0.2 mm; 19 = 0.5 mm.Published as part of T., Li & S.P., Sun, 2022, The genus Alexeter Förster (Hymenoptera, Ichneumonidae) in China, with descriptions of three new species, pp. 81-103 in European Journal of Taxonomy 789 (81) on page 90, DOI: 10.5852/ejt.2022.789.1633, http://zenodo.org/record/590636
Figs 4–8 in The genus Alexeter Förster (Hymenoptera, Ichneumonidae) in China, with descriptions of three new species
No full textFigs 4–8. Alexeter flavicoxa sp. nov., holotype, ♀ (GSFGPM). 4. Mesosoma, lateral view. 5. Mesoscutum and Scutellum, dorsal-lateral view. 6. Hind yongtarsomeres, lateral view. 7. Wings. 8. Propodeum, dorsal view. Scale bars: 4–6 = 0.2 mm; 7 = 0.5 mm; 8 = 0.1 mm.Published as part of T., Li & S.P., Sun, 2022, The genus Alexeter Förster (Hymenoptera, Ichneumonidae) in China, with descriptions of three new species, pp. 81-103 in European Journal of Taxonomy 789 (81) on page 86, DOI: 10.5852/ejt.2022.789.1633, http://zenodo.org/record/590636
Catalytic role for Arginine 188 in the C-C hydrolase catalytic mechanism for Escherichia coli MhpC and Burkholderia xenovorans LB400 BphD
No full textThe alpha/beta-hydrolase superfamily, comprised mainly of esterase and lipase enzymes, contains a family of bacterial C-C hydrolases, including MhpC and BphD which catalyze the hydrolytic C-C cleavage of meta-ring fission intermediates on the Escherichia coli phenylpropionic acid pathway and Burkholderia xenovorans LB400 biphenyl degradation pathway, respectively. Five active site amino acid residues (Arg-188, Asn-109, Phe-173, Cys-261, and Trp-264) were identified from sequence alignments that are conserved in C-C hydrolases, but not in enzymes of different function. Replacement of Arg-188 in MhpC with Gln and Lys led to 200- and 40-fold decreases, respectively, in k(cat); the same replacements for Arg-190 of BphD led to 400- and 700-fold decreases, respectively, in k(cat). Pre-steady-state kinetic analysis of the R188Q MhpC mutant revealed that the first step of the reaction, keto-enol tautomerization, had become rate-limiting, indicating that Arg-188 has a catalytic role in ketonization of the dienol substrate, which we propose is via substrate destabilization. Mutation of nearby residues Phe-173 and Trp-264 to Gly gave 4-10-fold reductions in k(cat) but 10-20-fold increases in K-m, indicating that these residues are primarily involved in substrate binding. The X-ray structure of a succinate-H263A MhpC complex shows concerted movements in the positions of both Phe-173 and Trp-264 that line the approach to Arg-188. Mutation of Asn-109 to Ala and His yielded 200- and 350-fold reductions, respectively, in k(cat) and pre-steady-state kinetic behavior similar to that of a previous S110A mutant, indicating a role for Asn-109 is positioning the active site loop containing Ser-110. The catalytic role of Arg-188 is rationalized by a hydrogen bond network close to the C-1 carboxylate of the substrate, which positions the substrate and promotes substrate ketonization, probably via destabilization of the bound substrate
Implicit large-eddy simulation of the stratocumulus-topped boundary layer: A grid sensitivity study
No full textA range of implicit large-eddy simulations of the stratocumulus-topped boundary layer is performed to study the influence of grid resolution on selected parameters including liquid water path and second and third moments of vertical velocity fluctuations. The simulations are based on two sets of aircraft measurements, which are also used to evaluate the results of the simulations. The specific case presented here indicates that simulations with a grid aspect ratio accounting for the anisotropic nature of the turbulence near the surface and at the top of the boundary layer lead to better agreement with measurements than simulations with an isotropic grid
Entrainment and detrainment rates from the piv measurements at the top of laboratory analogs of stratocumulus and cumulus clouds
No full textWe analyze mixing at the top of laboratory analogs of convective clouds: stratocumulus and cumulus to investigate entrainment of environmental air into the cloud. We retrieve two components of air velocity using Particle Image Velocimetry technique. Suitable image processing allows to determine cloud–clear air interface. Using velocity differences between cloudy and clear sides of the interface we calculate entrainment / detrainment rates
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