Diversity of hard-bottom fauna relative to environmental gradients in Kongsfjorden, Svalbard

A baseline study of hard-bottom zoobenthos in relation to environmental gradients in Kongsfjorden, a glacial fjord in Svalbard, is presented, based on collections from 1996 to 1998. The total species richness in 62 samples from 0 to 30 m depth along five transects was 403 species. Because 32 taxa could not be identified to species level and because 11 species are probably new to science, the total number of identified species was 360. Of these, 47 species are new for Svalbard waters. Bryozoa was the most diverse group. Biogeographic composition revealed features of both Arctic and sub-Arctic properties of the fauna. Species richness, frequency of species occurrence, mean abundance and biomass generally decreased towards the tidal glaciers in inner Kongsfjorden. Among eight environmental factors, depth was most important for explaining variance in the composition of the zoobenthos. The diversity was consistently low at shallow depths, whereas the non-linear patterns of species composition of deeper samples indicated a transitional zone between surface and deeper water masses at 15–20 m depth. Groups of “colonial” and “non-colonial” species differed in diversity, biogeographic composition and distribution by location and depth as well as in relation to other environmental factors. “Non-colonial” species made a greater contribution than “colonial” species to total species richness, total occurrence and biomass in samples, and were more influenced by the depth gradient. Biogeographic composition was sensitive to variation of zoobenthic characteristics over the studied depth range. A list of recorded species and a description of sampling sites are presented

A solid solution of ethyl and d₃-methyl 2-[(4-methylpyridin-2-yl)amino]-4-(pyridin-2-yl)thiazole-5-carboxylate

The synthesis of ethyl 2-[(4-methylpyridin-2-yl)amino)-4-(pyridin-2-yl)thiazole- 5-carboxylate via the Hantzsch reaction and partial in situ transesterification during recrystallization from methanol-d4 to the d3-methyl ester, resulting in the title solid solution, ethyl 2-[(4-methylpyridin-2-yl)amino)-4-(pyridin-2-yl)thia- zole-5-carboxylate–d3-methyl 2-[(4-methylpyridin-2-yl)amino)-4-(pyridin-2-yl)thiazole-5-carboxylate (0.88/0.12), 0.88C17H16N4O2S∙0.12C16D3H11N4O2S, is reported. The refined ratio of ethyl to d3-methyl ester in the crystal is 0.880 (6):0.120 (6). The pyridine ring is significantly twisted out of the plane of the approximately planar picoline thiazole ester moiety. N—H∙ ∙ ∙N hydrogen bonds between the secondary amino group and the pyridine nitrogen atom of an adjacent symmetry-related molecule link the molecules into polymeric hydrogen-bonded zigzag tapes extending by glide symmetry in the [001] direction. There is structural evidence for intramolecular N∙ ∙ ∙S chalcogen bonding and intermolecular weak C—H∙ ∙ ∙O hydrogen bonds between adjacent zigzag tapes

Structural Characterization of Two Polymorphs of 1-(4-Methylpyridin-2-yl)thiourea and Two Derived 2-Aminothiazoles

Two polymorphic forms of 1-(4-methylpyridin-2-yl)thiourea (1) and the crystal and molecular structures of the 2-aminothiazoles N-(4-methylpyridin-2-yl)-4-(pyridin-2-yl)thiazol-2-amine (2) and N-(4-methylpyridin-2-yl)-4-(pyrazin-2-yl)thiazol-2-amine (3), derived from 1 and the respective α-bromoketone via the Hantzsch reaction, are described. Both polymorphic forms 1α (space group P21/c, Z = 4) and 1β (space group P21/n, Z = 8) crystallize in the monoclinic system but exhibit distinctly different intermolecular hydrogen bonding patterns. Compound 2 (orthorhombic, space group Pca21, Z = 8) forms polymeric N–H⋯N hydrogen-bonded zigzag tapes in the polar crystal structure, with a significant twisting between the thiazole and pyridine rings. In contrast, the crystal structure of 3 (monoclinic, space group P21/c, Z = 4) features nearly planar centrosymmetric N–H⋯N hydrogen-bonded dimers, which are laterally joined through long C–H⋯N contacts, affording a π⋯π stacked layered structure

Protonation sites and hydrogen bonding in mono-hydrobromidesalts of two N,4-diheteroaryl 2-aminothiazoles

The synthesis and structural characterization of N-(6-methoxypyridin-3-yl)-4-(pyridin-2-yl)thiazol-2-amine mono-hydrobromide monohydrate (3) and N-(6-methoxypyridin-3-yl)-4-(pyrazin-2-yl)thiazol-2-amine mono-hydrobromide 0.35 methanol solvate (4) are reported. The crystal structures of 3 (monoclinic, space group P21/n, Z=4) and 4 (monoclinic, space group, C2/c, Z=8) feature N,4-diheteroaryl 2-aminothiazoles showing similar molecular conformations but different sites of protonation and thus distinctly different intermolecular hydrogen bonding patterns. In 3, Namine–H⋯Br−,N+pyridine–H⋯Owater, and Owater–H⋯Br− hydrogen bonds link protonated N-(6-methoxypyridin-3-yl)-4-(pyridin-2-yl)thiazol-2-amine and water molecules and bromide anions into a three-dimensional hydrogen-bonded network, whereas intermolecular N+methoxypyridine–H⋯Npyrazine hydrogen bonds result in hydrogen-bonded zigzag chains of protonated N-(6-methoxypyridin-3-yl)-4-(pyrazin-2-yl)thiazol-2-amine molecules in 4

Seaweeds and their communities in polar regions

Polar seaweeds typically begin to grow in late winter-spring, around the time of sea-ice break up. They can grow under very low light enabling distributions to depths of ≥40 m. Moreover, they are physiologically adapted to low temperatures. Intertidal species exhibit a remarkable stress tolerance against freezing, desiccation and salinity changes. Endemism is much greater in the Antarctic compared to the Arctic species. On rocky shores of the Antarctic Peninsula and of Spitsbergen >80% of the bottom can be covered by seaweeds with standing biomass levels ≥20 kg wet wt m-2. Species richness and biomass declines, however, towards higher latitudes. Seaweeds are the dominant organisms in coastal waters and thus play important roles in benthic food webs and are likely to be of particular importance to benthic detrital food chains. Chemical defenses against herbivores are common in Antarctic, but not in Arctic seaweeds. More research is needed especially to study the effects of global climate changes

Early Weight Bearing Following First TMT Arthrodesis

Category: Midfoot/Forefoot Introduction/Purpose: The modified Lapidus arthrodesis is an accepted method of correcting varying degrees of hallux valgus with or without associated first ray insufficiency. Improved operative techniques have led to more reliable outcomes and lower incidence of nonunion. As a result, the modified Lapidus procedure has increased in popularity. Historically, surgeons have followed cautious postoperative protocols, initially restricting weight bearing until bone consolidation is confirmed radiographically. More recently, an alternative approach to postoperative management has been proposed, allowing patients to bear weight as tolerated two weeks after surgery with the goal of improving patient compliance while minimizing postoperative disability. The purpose of this study is to compare outcomes of patients randomized to either early weight bearing or standard non-weight bearing postoperative course following modified Lapidus arthrodesis. Methods: We determined that at least 130 patients would need to be enrolled in this study to achieve statistical significance (p < 0.05). Beginning in 2012, patients with hallux valgus indicated for modified Lapidus arthrodesis were assigned to either the investigational Group A (early weight bearing) or to the control Group B (standard of care) by a random number generator. All patients underwent modified Lapidus arthrodesis by one of the three senior authors (JGA, DRB, JDM). Specific demographic, clinical, patient-centered, and radiographic data were collected during the preoperative visit, the operative procedure, and at defined intervals during the postoperative period. The primary outcome variable was defined as first tarsometatarsal joint fusion at six months. Results: To date, 100 subjects have been enrolled, 57 of whom (40 patients in Group A, 17 patients in Group B) have completed one year of follow up. At six months, 38/40 patients in Group A had achieved radiographic union, compared to 17/17 patients in Group B (p = 0.495). Smoking status, BMI, and age at surgery were not found to be significantly associated with rate of union in either group. Patients in Group A required less time to reach full weight bearing status (p < 0.001). At six weeks after surgery, Group A reported significantly higher levels of physical function and overall composite scores on the SF-36 questionnaire. The rate of adverse events was not significantly different between the two groups at any postoperative timepoint. Conclusion: Though data collection is ongoing, our results indicate that clinical, patient-centered, and radiographic outcomes were comparable following modified Lapidus arthrodesis in both the early weight bearing and standard of care patient groups. Early weight bearing does not appear to increase the rate of adverse events or significantly slow rate of fusion, and also reduces postoperative disability

Estimating the Reduction in the Radiation Burden From Nuclear Cardiology Through Use of Stress-Only Imaging in the United States and Worldwide

Not availabl