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Abstract

The well−known Jurassic macrofloras from Hope Bay at the northernmost tip of the Antarctic Peninsula continue to yield new taxa . This paper reports on a new type of plant re− productive organ. The affinity of this organ r emains unclear; it may be affiliated with the Schizaceae or Osmundaceae, but similarities to po llen organs of the Podocarpaceae are also discussed. Because the fossils differ from hitherto known Mesozoic fertile fronds and conifer pollen organs in some details, the new taxon, Spesia antarctica nov. gen. et sp. is proposed.
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Abstract

A method for evaluating the dynamic characteristics of force transducers against small and short-duration impact forces is developed. In this method, a small mass collides with a force transducer and the impact force is measured with high accuracy as the inertial force of the mass. A pneumatic linear bearing is used to achieve linear motion with sufficiently small friction acting on the mass, which is the moving part of the bearing. Small and short-duration impact forces with a maximum impact force of approximately 5 N and minimum half-value width of approximately 1 ms are applied to a force transducer and the impulse responses are evaluated.
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Abstract

The nonlinearity parameter B/A, internal pressure, and acoustic impedance are calculated for a room temperature ionic liquid, i.e. for 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide for temperatures from (288.15 to 318.15) K and pressures up to 100 MPa. The B/A calculations are made by means of a thermodynamic method. The decrease of B/A values with the increasing pressure is observed. At the same time B/A is temperature independent in the range studied. The results are compared with corresponding data for organic molecular liquids. The isotherms of internal pressure cross at pressure in the vicinity of 70 MPa, i.e. in this range the internal pressure is temperature independent.
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