359 research outputs found
Extremely Sub-wavelength Planar Magnetic Metamaterials
We present highly sub-wavelength magnetic metamaterials designed for
operation at radio frequencies (RFs). A dual layer design consisting of
independent planar spiral elements enables experimental demonstration of a unit
cell size (a) that is ~ 700 times smaller than the resonant wavelength
({\lambda}0). Simulations indicate that utilization of a conductive via to
connect spiral layers permits further optimization and we achieve a unit cell
that is {\lambda}0/a ~ 2000. Magnetic metamaterials are characterized by a
novel time domain method which permits determination of the complex magnetic
response. Numerical simulations are performed to support experimental data and
we find excellent agreement. These new designs make metamaterial low frequency
experimental investigations practical and suggest their use for study of
magneto-inductive waves, levitation, and further enable potential RF
applications.Comment: 5 pages, 4 figure
Floriparicapitus, a new genus of lecanicephalidean tapeworm (Cestoda) from sawfishes (Pristidae) and guitarfishes (Rhinobatidae) in the Indo-West Pacific
Floriparicapitus n. gen. (Cestoda: Lecanicephalidea), with F. euzeti n. gen. n. sp. as its
type, is erected to house 3 new tapeworm species and 2 known species that are
transferred to the new genus, all parasitizing sawfishes and guitarfishes (order
Rhinopristiformes) in Indo-Pacific waters. The new genus differs from the 20 valid
lecanicephalidean genera in its possession of a large scolex bearing a laterally
expanded apical organ in the form of a rugose sheet in combination with a cirrus
conspicuously armed with spinitriches and 3 pairs of excretory vessels. It most closely
resembles Lecanicephalum, but differs conspicuously in its possession of 3, rather
than 1, pair of excretory vessels. Two new species are described from sawfishes:
Floriparicapitus euzeti n. sp., from Pristis clavata and Floriparicapitus juliani n. sp. from
Pristis microdon, both from Australia. Floriparicapitus plicatilis n. sp. is described from
the guitarfish Glaucostegus typus in Australia and the guitarfish Glaucostegus thouin in
Malaysian Borneo. Two species formerly assigned to Cephalobothrium are transferred
to the new genus; Floriparicapitus variabilis (Southwell, 1911) n. comb. from the
sawfish Anoxypristis cuspidata in Sri Lanka and Floriparicapitus rhinobatidis
(Subhapradha, 1955) n. comb. from the guitarfish Glaucostegus granulatus in India.
The species from guitarfish differ conspicuously from those parasitizing sawfish in their
possession of only 4 (F. plicatilis n. sp.) or 5 (F. rhinobatidis n. comb.) testes per
proglottid, versus 9 or more in the 3 sawfish-parasitizing species. The latter 3 species
differ from one another in scolex width, acetabular size, number of proglottids, and
cirrus sac size. As it stands, the new genus appears to be restricted to a subclade of
the Rhinopristiformes consisting of the sawfishes and species of Glaucostegus
A Saxon Fish Weir and undated fish trap frames near Ashlett Creek, Hampshire, UK: static structures on a dynamic foreshore
This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this record.The remains of a wooden V-shaped fish weir and associated structures have been
discovered near Ashlett Creek on the tidal mudflats of Southampton Water in
Hampshire, southern Britain. Radiocarbon dating of oak roundwood stakes taken from
the main weir structure date it to the middle Saxon period. Clusters of as-yet undated
roundwood posts within the catchment area of the weir are interpreted as the frames
for fish traps that are assumed to pre- or post-date the operational period of the weir
itself. The weir is contemporary with wooden V-shaped fish weirs found elsewhere in
southern and central Britain, and also Ireland, but its circular catchment ‘pound’
remains restricted, in these islands, to the Solent and Severn estuaries: it has a close
parallel with another Saxon-era weir on the nearby Isle of Wight. It also shows
striking structural similarities with examples in use today in Basse Normandy, on the
southern shore of the English Channel. The paper discusses the function and operation
of the weir, and places it in its social and historical context. Regressive cartography
demonstrates that the structures have become exposed as a result of saltmarsh retreat
in this area of Southampton Water since the 19th century. The radiocarbon dates
returned for the posts demonstrate that this transgression of the marsh must have been
preceded by a prolonged period of progradation, which covered and preserved the
site; its subsequent re-exposure has negative implications for its survival.The fieldwork underpinning this research was carried out using equipment
and facilities provided by the Centre for Maritime Archaeology of the University of
Southampton. The authors themselves met incidental costs. Radiocarbon dating was
financed from an internal University of Exeter research allowance
Crystallization of two forms of a cyclodextrin inclusion complex containing a common organic guest
The isolation and structural elucidation by single crystal Xray diffraction of triclinic and monoclinic modifications of an inclusion complex of b-cyclodextrin with the same guest, methylparaben, are reported
Orders out of chaos – molecular phylogenetics reveals the complexity of shark and stingray tapeworm relationships
Novel molecular data are presented to resolve the long-standing issue of the non-monophyly of the elasmobranch-hosted tapeworm order Tetraphyllidea relative to the other acetabulate eucestode orders. Bayesian Inference analyses of various combinations of full ssrDNA, and full or partial lsrDNA (D1-D3), sequence data, which included 134 species representing 97 genera across the 15 eucestode orders, were conducted. New ssrDNA data were generated for 82 species, partial lsrDNA data for 53 species, and full lsrDNA data for 29 species. The monophyly of each of the elasmobranch-hosted orders Cathetocephalidea, Litobothriidea, Lecanicephalidea, and Rhinebothriidea was confirmed, as was the non-monophyly of the Tetraphyllidea. Two relatively stable groups of tetraphyllidean taxa emerged and are hereby designated as new orders. The Onchoproteocephalidea n. ord. is established to recognize the integrated nature of one undescribed and ten described genera of hook-bearing tetraphyllideans, previously of the family Onchobothriidae, with the members of the order Proteocephalidea. The Phyllobothriidea n. ord. is established for a subset of 12 non-hooked genera characterized by scoleces bearing four bothridia each with an anterior accessory sucker; most parasitise sharks and have been assigned to the Phyllobothriidae at one time or another. Tentative ordinal placements are suggested for 8 additional genera; placements for the remaining tetraphyllidean genera have not yet emerged. We propose these 17 genera remain in the “Tetraphyllidea”. Among these, particularly labile across analyses were Anthobothrium, Megalonchos, Carpobothrium, Calliobothrium, and Caulobothrium. The unique association of Chimaerocestus with holocephalans, rather than with elasmobranchs, appears to represent a host-switching event. Both of the non-elasmobranch hosted clades of acetabulate cestodes (i.e., Proteocephalidea and Cyclophyllidea and their kin) appear to have had their origins with elasmobranch cestodes. Across analyses, the sister group to the clade of “terrestrial” cestode orders was found to be an elasmobranch-hosted genus; as was the sister to the freshwater fish and tetrapod-hosted Proteocephalidea. Whilst further data are required to resolve outstanding nomenclatural and phylogenetic issues, the present analyses contribute significantly to an understanding of the evolutionary radiation of the entire Cestoda. Clearly, elasmobranch tapeworms comprise the backbone of cestode phylogeny
An overview of the tapeworms of vertebrate bowels of the earth
entire volume OA; selected chapter posted hereCopyright: © The University of Kansas, Natural History Museum. This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License
Polymorphism in sulfadimidine/4- aminosalicylic acid cocrystals: solid-state characterization and physicochemical properties
YesPolymorphism of crystalline drugs is a common phenomenon. However, the number of
reported polymorphic cocrystals is very limited. In this work, the synthesis and solid state
characterisation of a polymorphic cocrystal composed of sulfadimidine (SD) and 4-
aminosalicylic acid (4-ASA) is reported for the first time. By liquid-assisted milling, the
SD:4-ASA 1:1 form I cocrystal, the structure of which has been previously reported, was
formed. By spray drying, a new polymorphic form (form II) of the SD:4-ASA 1:1 cocrystal
was discovered which could also be obtained by solvent evaporation from ethanol and
acetone. Structure determination of the form II cocrystal was calculated using high resolution
X-ray powder diffraction. The solubility of the SD:4-ASA 1:1 cocrystal was dependent on the
pH and predicted by a model established for a two amphoteric component cocrystal. The form
I cocrystal was found to be thermodynamically more stable in aqueous solution than form II,
which showed transformation to form I. Dissolution studies revealed that the dissolution rate
of SD from both cocrystals was enhanced when compared to a physical equimolar mixture
and pure SD.Science Foundation Ireland (SFI) under Grant Number 07/SRC/B1158 and SFI/12/RC/2275
2-(1H-Benzotriazol-1-yl)-1-phenylethanol
In the title compound, C14H13N3O, the benzotriazole ring is oriented at a dihedral angle of 13.43 (4)° with respect to the phenyl ring. In the crystal structure, intermolecular O—H⋯N hydrogen bonds link the molecules into chains along the b axis. Aromatic π–π contacts between benzene rings and between triazole and benzene rings [centroid–centroid distances = 3.8133 (8) and 3.7810 (8) Å, respectively], as well as a weak C—H⋯π interaction involving the phenyl ring, are also observed
Identification of a new cocrystal of citric acid and paracetamol of pharmaceutical relevance
Cocrystals have been increasingly recognized as an attractive alternative delivery form for solid drug products. In this work, Raman spectroscopy, X-ray powder diffraction/X-ray crystallography, and differential scanning calorimetry have been used to study the phenomenon of cocrystal formation in stoichiometric mixtures of citric acid with paracetamol. Raman spectroscopy was particularly useful for the characterization of the products and was used to determine the nature of the interactions in the cocrystals. It was observed that little change in the vibrational modes associated with the phenyl groups of the respective reactants took place upon cocrystal formation but changes in intensities of the vibrational modes associated with the amide and the carboxylic acid groups were observed upon cocrystal formation. Several new vibrational bands were identified in the cocrystal which were not manifest in the raw material and could be used as diagnostic features of cocrystal formation. An understanding of the effects of cocrystal formation on the vibrational modes was obtained by the complete assignment of the spectra of the starting materials and of the cocrystal component. The results show that the cocrystals was obtained in a 2:1 molar ratio of paracetamol to citric acid. The asymmetric unit of the crystal contains two paracetamol molecules hydrogen-bonded to the citric acid; one of these acts as a phenolic-OH hydrogen bond donor to the carbonyl of a carboxylic acid arm of citric acid. In contrast, the other phenolic-OH acts as a hydrogen bond acceptor from the quaternary C-OH of citric acid. © 2011 The Royal Society of Chemistry
1-[2-(2,6-Dichlorobenzyloxy)-2-(2-furyl)ethyl]-1H-benzimidazole
In the molecule of the title compound, C20H16Cl2N2O2, the planar benzimidazole ring system is oriented with respect to the furan and dichlorobenzene rings at dihedral angles of 53.39 (6) and 31.04 (5)°, respectively. In the crystal structure, intermolecular C—H⋯Cl hydrogen bonds link the molecules into centrosymmetric R
2
2(8) dimers. These dimers are connected via a C—H⋯π contact between the benzimidazole and the furan rings, and π–π contacts between the benzimidazole and dichlorobenzene ring systems [centroid–centroid distances = 3.505 (1), 3.567 (1), 3.505 (1) and 3.567 (1) Å]
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