1,130 research outputs found
Copper(II)- and gold(III)-mediated cyclization of a thiourea to a substituted 2-aminobenzothiazole
Benzothiazole derivatives are a class of privileged molecules due to their biological activity and pharmaceutical applications. One route to these molecules is via intramolecular cyclization of thioureas to form substituted 2-aminobenzothiazoles, but this often requires harsh conditions or employs expensive metal catalysts. Herein, the copper(II)- and gold(III)-mediated cyclizations of thioureas to substituted 2-aminobenzothiazoles are reported. The single-crystal X-ray structures of the thiourea N-(3-methoxyphenyl)-N\u27- (pyridin-2-yl)thiourea, C13H13N3OS, and the intermediate metal complexes aquabis[5-methoxy-N-(pyridin-2-yl-κN)-1,3-benzothiazol-2-amine-κN3]copper(II) dinitrate, [Cu(C13H11N3OS)2(H2O)](NO3)2, and bis{2-[(5-methoxy-1,3-benzothiazol- 2-yl)amino]pyridin-1-ium} dichloridogold(I) chloride monohydrate, (C13H12N3OS)2[AuCl2]Cl⋅H2O, are reported. The copper complex exhibits a distorted trigonal–bipyramidal geometry, with direct metal-to-benzothiazoleligand coordination, while the gold complex is a salt containing the protonated uncoordinated benzothiazole, and offers evidence that metal reduction (in this case, AuIII to AuI) is required for the cyclization to proceed. As such, this study provides further mechanistic insight into the role of the metal cations in these transformations
Low Frequency Gravitational Waves from Black Hole MACHO Binaries
Nakamura, Sasaki, Tanaka, and Thorne have recently estimated the initial
distribution of binary MACHOs in the galactic halo assuming that the MACHOs are
primordial half solar mass black holes, and considered their coalescence as a
possible source for ground-based interferometer gravitational wave detectors
such as LIGO. Evolving their binary distribution forward in time to the
present, the low-frequency (10^{-5} < f < 10^{-1} Hz) spectrum of gravitational
waves associated with such a population of compact binaries is calculated. The
resulting gravitational waves would form a strong stochastic background in
proposed space interferometers such as LISA and OMEGA. Low frequency
gravitational waves are likely to become a key tool for determining the
properties of binaries within the dark MACHO population.Comment: 8 pages + 2 ps figures; AASTe
English Channel towed sledge seabed images. Phase 2: Analysis of selected tow images
During the 1970s and 1980s, the late Dr Norman Holme undertook extensive towed sledge surveys in the English Channel and some in the Irish Sea. Only a minority of the resulting images were analysed and reported before his death in 1989 but logbooks, video and film material has been archived in the National Marine Biological Library (NMBL) in Plymouth. A study was therefore commissioned by the Joint Nature Conservation Committee and as a part of the Mapping European Seabed Habitats (MESH) project to identify the value of the material archived and the procedure and cost to undertake further work (Phase 1 of the study reported here: Oakley & Hiscock, 2005).
Some image analysis was undertaken as a part of Phase 1. Phase 2 (this report) was to further analyse selected images. Having determined in Phase 1 that only the 35 mm photographic transparencies provided sufficient clarity to identify species and biotopes, the tows selected for analysis were ones where 35mm images had been taken. The tows selected for analysis of images were mainly in the vicinity of Plymouth and especially along the area between Rame Head and the region of the Eddystone.
The 35 mm films were viewed under a binocular microscope and the taxa that could be recognised recorded in note form. Twenty-five images were selected for inclusion in the report.
Almost all of the images were of level sediment seabed. Where rocks were included, it was usually unplanned and the sled was hauled before being caught or damaged. The main biotopes or biotope complexes identified were:
SS.SMU.CSaMu. Circalittoral sandy mud. Extensively present between the shore and the Eddystone Reef complex and at depths of about 48 to 52 m. At one site offshore of Plymouth Sound, the turret shell Turritella communis was abundant. In some areas, this biotope had dense anemones, Mesacmaea mitchelli and (more rarely) Cerianthus lloydii. Queen scallops, Aequipecten opercularis and king scallops, Pecten maximus, were sometimes present in small numbers. Hard substratum species such as hydroids, dead mens fingers Alcyonium digitatum and the cup coral Caryophyllia smithii occurred in a few places, probably attached to shells or stones beneath the surface.
South of the spoil ground off Hilsea Point at 57m depth, the sediment was muddier but is still assigned to this biotope complex. It is notable that three small sea pens, most likely Virgularia mirabilis, were seen here.
SS.SMx.CMx. Circalittoral mixed sediment. Further offshore but at about the same depth as SS.SMU.CSaMu occurred, coarse gravel with some silt was present. The sediment was characterised must conspicuously by small queen scallops, Aequipecten opercularis. Peculiarly, there were ‘bundles’ of the branching bryozoan Cellaria sp. – a species normally found attached to rock. It could not be seen whether these bundles of Cellaria had been brought-together by terebellid worms but it is notable that Cellaria is recorded in historical surveys. As with many other sediments, there were occasional brittle stars, Ophiocomina nigra and Ophiura ophiura. Where sediments were muddy, the burrowing anemone Mesacmaea mitchelli was common. Where pebbles or cobbles occurred, there were attached species such as Alcyonium digitatum, Caryophyllia smithii and the fleshy bryozoan Alcyonidium diaphanum.
Undescribed biotope. Although most likely a part of SS.SMx.CMx, the biotope visually dominated by a terebellid worm believed to be Thelepus cincinnatua, is worth special attention as it may be an undescribed biotope. The biotope occurred about 22 nautical miles south of the latitude of the Eddystone and in depths in excess of 70 m.
SS.SCS.CCS.Blan. Branchiostoma lanceolatum in circalittoral coarse sand with shell gravel at about 48m depth and less. This habitat was the ‘classic’ ‘Eddystone Shell Gravel’ which is sampled for Branchiostoma lanceolatum. However, no Branchiostoma lanceolatum could be seen. The gravel was almost entirely bare of epibiota. There were occasional rock outcrops or cobbles which had epibiota including encrusting calcareous algae, the sea fan Eunicella verrucosa, cup corals, Caryophyllia smithii, hydroids and a sea urchin Echinus esculentus.
The variety of species visible on the surface is small and therefore identification to biotope not usually possible.
Historical records from sampling surveys that used grabs and dredges at the end of the 19th century and early 20th century suggest similar species present then. Illustrations of some of the infaunal communities from work in the 1920’s is included in this report to provide a context to the epifaunal photographs
English Channel towed sledge seabed images. Phase 1: scoping study and example analysis
During the 1970’s and 1980’s, the late Dr Norman Holme undertook extensive towed
sledge surveys in the English Channel and some in the Irish Sea. Only a minority of the
resulting images were analysed and reported before his death in 1989 but logbooks, video
and film material has been archived in the National Marine Biological Library (NMBL) in
Plymouth. A scoping study was therefore commissioned by the Joint Nature Conservation
Committee and as a part of the Mapping European Seabed Habitats (MESH) project to
identify the value of the material archived and the procedure and cost to undertake further
work.
The results of the scoping study are:
1. NMBL archives hold 106 videotapes (reel-to-reel Sony HD format) and 59 video
cassettes (including 15 from the Irish Sea) in VHS format together with 90 rolls of 35 mm
colour transparency film (various lengths up to about 240 frames per film). These are
stored in the Archive Room, either in a storage cabinet or in original film canisters.
2. Reel-to-reel material is extensive and had already been selectively copied to VHS
cassettes. The cost of transferring it to an accepted ‘long-life’ medium (Betamax) would be
approximately £15,000. It was not possible to view the tapes as a suitable machine was
not located. The value of the tapes is uncertain but they are likely to become beyond
salvation within one to two years.
3. Video cassette material is in good condition and is expected to remain so for several
more years at least. Images viewed were generally of poor quality and the speed of tow
often makes pictures blurred. No immediate action is required.
4. Colour transparency films are in good condition and the images are very clear. They
provide the best source of information for mapping seabed biotopes. They should be
scanned to digital format but inexpensive fast copying is problematic as there are no
between-frame breaks between images and machines need to centre the image based on
between-frame breaks. The minimum cost to scan all of the images commercially is
approximately £6,000 and could be as much as £40,000 on some quotations. There is a
further cost in coding and databasing each image and, all-in-all it would seem most
economic to purchase a ‘continuous film’ scanner and undertake the work in-house.
5. Positional information in ships logs has been matched to films and to video tapes.
Decca Chain co-ordinates recorded in the logbooks have been converted to latitude and
longitude (degrees, minutes and seconds) and a further routine developed to convert to
degrees and decimal degrees required for GIS mapping. However, it is unclear whether
corrections to Decca positions were applied at the time the position was noted. Tow tracks
have been mapped onto an electronic copy of a Hydrographic Office chart.
6. The positions of start and end of each tow were entered to a spread sheet so that they
can be displayed on GIS or on a Hydrographic Office Chart backdrop. The cost of the
Hydrographic Office chart backdrop at a scale of 1:75,000 for the whole area was £458
incl. VAT.
7. Viewing all of the video cassettes to note habitats and biological communities, even by
an experienced marine biologist, would take at least in the order of 200 hours and is not
recommended.
English Channel towed sledge seabed images. Phase 1: scoping study
and example analysis.
6
8. Once colour transparencies are scanned and indexed, viewing to identify seabed
habitats and biological communities would probably take about 100 hours for an
experienced marine biologist and is recommended.
9. It is expected that identifying biotopes along approximately 1 km lengths of each tow
would be feasible although uncertainties about Decca co-ordinate corrections and exact
positions of images most likely gives a ±250 m position error. More work to locate each
image accurately and solve the Decca correction question would improve accuracy of
image location.
10. Using codings (produced by Holme to identify different seabed types), and some
viewing of video and transparency material, 10 biotopes have been identified, although
more would be added as a result of full analysis.
11. Using the data available from the Holme archive, it is possible to populate various
fields within the Marine Recorder database. The overall ‘survey’ will be ‘English Channel
towed video sled survey’. The ‘events’ become the 104 tows. Each tow could be described
as four samples, i.e. the start and end of the tow and two areas in the middle to give
examples along the length of the tow. These samples would have their own
latitude/longitude co-ordinates. The four samples would link to a GIS map.
12. Stills and video clips together with text information could be incorporated into a
multimedia presentation, to demonstrate the range of level seabed types found along a
part of the northern English Channel. More recent images taken during SCUBA diving of
reef habitats in the same area as the towed sledge surveys could be added to the Holme
images
Occurrence of the physonect siphonophore Apolemia uvaria (Lesueur, 1815) off Plymouth and in south-west England
In September 2007, observations were made of a siphonophore in surface waters and near to the seabed by sea users off south
Devon and south-east Cornwall. The same siphonophore was also recorded from regular samples collected offshore of
Plymouth. The species is identified as Apolemia uvaria, which had not previously been recorded off Plymouth. It was
sampled until March 2008 and re-appeared, in smaller numbers, in autumn 2008 until February 2009 but was not reliably
reported in autumn 2009 (to end of October). The occurrence is unlikely to be due to sea warming, but more likely some variation
in oceanic currents, possibly influxes of Atlantic wate
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