1,363 research outputs found

    Igneous processes within late Precambrian volcanic centres near Whitwick, northwestern Charnwood Forest

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    Precambrian rocks in northwestern Chamwood Forest differ markedly from their lateral equivalents to the east and south. They are subdivided into the Whitwick Volcanic Complex, of massive to intensely brecciated high-silica andesites and porphyritic dacites, and the Chamwood Lodge Volcanic Formation, which is a thickly bedded sequence of mainly andesitic to dacitic volcanic breccias and lapillituffs. Lithological elements common to both of these units are indicated by field, petrographical and geochemical evidence, which suggests the existence of two 'genetic associations' of rock-types. These associations, and various other units that are distinctive to this region, form the basis of a model that views the Whitwick Complex as an aggregation of magmatic feeder bodies that supplied material, in the form of blocks and lapilli, to a volcaniclastic apron represented by the Chamwood Lodge Formation. The analogues for these rocks can be drawn from the axial magmatic zones of modem or geologically very young volcanic arc systems. The high-silica (dacitic and rhyolitic) Charnian magmas were intruded into unconsolidated wet sediments, resulting in physical interactions that generated peperitic lithologies and related breccias. By contrast, the andesitic magmas may have extruded subaerially as lava domes that periodically collapsed, giving rise to block and ash pyroclastic flows and lahars

    The effects of arcjet operating condition and constrictor geometry on the plasma plume

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    Measurements of plasma number density and electron temperature were obtained in the plumes of lab arcjet thrusters using electrostatic probes of both spherical and cylindrical geometry. The two arcjet thrusters used had different constrictor and/or nozzle geometries and operated on mixtures of nitrogen, hydrogen, and ammonia to simulate the decomposition products of hydrazine and ammonia. An increase in the measured electron density was observed for both geometries with increasing arc power at a constant mass flow rate and with increasing mass flow rate at a constant arc current. For a given operating condition, the electron number density decreased exponentially off centerline and followed an inverse distance squared relationship along the thrust axis. Typical measured electron temperatures ranged from 0.1 to 0.2 eV

    Life just got complicated

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    The fossil record of ancient life is, in general, poor. Certainly, fossils are abundant in many rock successions and may reveal remarkable details about evolution and environmental change, but they typically consist of disarticulated or broken skeletal material, such as shells, bones and teeth. Even worse, the record of entirely (or largely) soft-bodied organisms, such as jellyfish and worms, is extremely scant, despite the fact that such animals dominate modern marine environments and presumably did so in the past. The reason is obvious — such organisms are highly susceptible to post-mortem decay and typically decompose more rapidly than the ‘normal’ processes of fossilisation operate. This significantly blurs our view of ancient life, with obvious consequences for those interested in understanding evolution and past ecosystems

    Magma mixing in the South Leicestershire diorite : evidence from an Ordovician pluton at Croft Quarry

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    At Croft Quarry, exposures of a pluton belonging to the South Leicestershire Diorite suite have revealed a complex history of multiple intrusion. Soon after emplacement of the main-stage quartz-diorite, the partially crystallised pluton received an influx of magma which became dispersed and is now seen as partially assimilated dioritic xenoliths. A much later episode of intrusion occurred when the pluton had cooled sufficiently to be capable of fracturing. It resulted in a spectacular swarm of synplutonic quartz-diorite/tonalite sheets with contacts indicating that the host quartz-diorite was locally remobilized, disrupting and net-veining the later sheets. These features are typical of ‘magma mixing’ phenomena, and suggest an underlying process that may account for some of the geochemical and petrographical variations previously noted within the South Leicestershire diorites

    2,4-Disulfonyl Phenyl Butyl Nitrone, Its Salt and Their Use as Pharmaceuticals

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    2,4-disulfonyl α-phenyl-tert-butyl nitrone and its pharmaceutically acceptable salts are disclosed. These materials are useful as pharmaceutical agents for oral or parenteral, e.g. intravenous administration to patients suffering from acute central nervous system oxidation as occurs in a stroke or from gradual central nervous system oxidation which can exhibit itself as progressive central nervous system function loss. The materials are also used to ameliorate the side effects of oxidative-damage causing antineoplastic disease treatments

    2,4-Disulfonyl Phenyl Butyl Nitrone, Its Salt and Their Use as Pharmaceuticals

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    2,4-disulfonyl α-phenyl-tert-butyl nitrone and its pharmaceutically acceptable salts are disclosed. These materials are useful as pharmaceutical agents for oral or parenteral, e.g. intravenous administration to patients suffering from acute central nervous system oxidation as occurs in a stroke or from gradual central nervous system oxidation which can exhibit itself as progressive central nervous system function loss. The materials are also used to ameliorate the side effects of oxidative-damage causing antineoplastic disease treatments

    2,4-Disulfo Phenyl Butyl Nitrone, Its Salt and Their Use as Pharmaceuticals

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    2,4-disulfonyl α-phenyl-tert-butyl nitrone and its pharmaceutically acceptable salts are disclosed. These materials are useful as pharmaceutical agents for oral or parenteral, e.g. intravenous administration to patients suffering from acute central nervous system oxidation as occurs in a stroke or from gradual central nervous system oxidation which can exhibit itself as progressive central nervous system function loss. The materials are also used to ameliorate the side effects of oxidative-damage causing antineoplastic disease treatments

    Farm shop safety program for vocational agriculture departments in Tennessee

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    This study was undertaken to improve safety In farm shop instruction in vocational agriculture in Tennessee. The specific objectives of the study were: 1. To determine the general safety conditions in school from mechanics shops in Tennessee. 2. To determine the rate, cause, and character of accidents in school farm mechanics shops during the period 1953 - 1956. 3. To develop a set of suggestions for a safety program in farm shop work in vocational agriculture in Tennessee

    2,4-Disulfonyl Phenyl Butyl Nitrone, Its Salt and Their Use as Pharmaceuticals Free Radical Traps

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    2,4-disulfonyl α-phenyl-tert-butyl nitrone and its pharmaceutically acceptable salts are disclosed. These materials are useful as pharmaceutical agents for oral or intravenous administration to patients suffering from acute central nervous system oxidation as occurs in a stroke or from gradual central nervous system oxidation which can exhibit itself as progressive central nervous system function loss
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