Univ., Diss.--Bayreuth, 1998.

No description available.

A multi-element soil extraction procedure (P, K, Mg, and Ca) using a mixed cation/anion exchange resin has been developed and its performance evaluated. Ion uptake to and recovery from the resin were highly reproducible over the concentration ranges typically experienced in soil. The effects on the overall reproducibility of changing various experimental parameters such as soil:water:resin ratios were quantified. Plant nutrient uptake and yield parameters obtained from either field (coconut) or pot (rye-grass) experiments using tropical or temperate soils have been used to evaluate the predictive capabilities of the proposed method. Comparisons with existing more widely acceptable soil extractants are made. The proposed method generally gave highly significant correlations with crop data which were independent of soil type. The possibility of including a simultaneous multi-element analytical step, which greatly increases the overall advantages of the resin procedure, has also been assessed.

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1924. / by Roger Cutting, Harry R. Hammond. / B.S.

No description available.

Disputatio--Méd., 1647. / On lit à la fin : Proponebat Lutetiae Bertinus Dieuxivoye, Cenomanus, Anno R. S. H. 1647. Recueil Thoisy, Matières ecclésiastiques, in-4 °, tome LXX, division Polygraphie.

Th.--Méd.--Paris, 1807. / Voyez tome 4, page , N ° 98. Paris, 1807.

Abh. techn. Wiss. Zürich, 1985 ; Diss. ETH Nr. 7888.

Actuellement, l’immense majorité des aimants supraconducteurs, notamment d’IRM, sont refroidis par un bain d’hélium liquide à pression atmosphérique. Néanmoins, ce type de refroidissement est onéreux et impose des contraintes sécuritaires importantes pour les grands volumes. Pour ces raisons, le refroidissement des aimants supraconducteurs est souhaitable sans l’hélium liquide. L’utilisation de cryogénérateur permet de refroidir par conduction solide jusqu’à 4 K et ainsi supprimer l’hélium liquide. Néanmoins, les faibles puissances disponibles combiner aux difficultés de mise en œuvre de ce type de refroidissement rendent difficile l’utilisation dans ces conditions du NbTi. En revanche à 10 K, la puissance des cryogénérateurs augmente d’un facteur 10, mais l’utilisation d’un supraconducteur à haute température critique est alors nécessaire. Notre choix s’est porté sur les conducteurs MgB2 R & W qui ont l’avantage d’être relativement économique à mettre en œuvre, mais qui ont, en revanche, le défaut d’être sensible à la déformation. Il est donc nécessaire d’être soigneux lors de leurs bobinages pour ne pas dégrader leurs performances supraconductrices. Dans le cadre de cette thèse, nous avons développé un insert froid refroidis par conduction solide permettant de mesurer le courant critique des conducteurs MgB2 R & W ainsi que des maquettes. Pour ce faire, un nouveau type de contact thermique à base de nitrure d’aluminium a été développé. En complément, nous avons conçu deux maquettes d’aimant MgB2 R & W : un solénoïde et une double galette. Cette dernière a été fabriquée (grâce à une nouvelle méthode de bobinage brevetée) et testée avec succès. / Currently, the majority of superconducting magnets, including MRI, are cooled by a bath of liquid helium at atmospheric pressure. Nevertheless, this type of cooling is expensive and imposes significant security constraints for large volumes. For these reasons, the cooling of superconducting magnets is desirable without liquid helium. Cryocooler provides dry cooling to 4 K without any liquid helium. However, the power available is low and dry cooling is difficult. In these conditions, it is complicate to use NbTi with dry cooling. But if we increase the operating temperature to 10 K, the power of cryocooler increases by a factor of ten. Nevertheless in this case, it is necessary to use of a high critical temperature superconductor. We choose to use MgB2 R & W conductors because it is relatively low cost but it has the handicap to be sensible at mechanical stress. It is therefore necessary to be careful during their winding to not degrade their superconducting performance. As part of this thesis, we have developed a dry test facility to measure the critical current of MgB2 R & W conductors as well as mock-ups. To do this, a new type of thermal contact based on aluminum nitride has been developed. In addition to this development, we designed two MgB2 R & W magnet mock-ups: a solenoid and a double pancake. The double pancake was manufactured (with a new patented winding method) and it has been successfully tested.

A study of the feeding ecology of the flounder in the Ythan estuary was carried out between October 1970 and August 1973. The diet of the fish varied along the length of the estuary. On the mudflats in the upper estuary C orophium vo lu tat or was the main food item with Nereis divers color and Hydrobia ulvae secondarily important, but on the very soft mudflats in the middle estuary small oligocbaetee (mainly Peloscolex benedeni) and polychaetes predominated in the diet. Over mussel beds 3\Terels dlveraicolor and Carcinus maenas were important and the lower and outer part elupeids were taken in large quantities by the older age groups. Intensive study on one mudflat" the Sleek of Tai'ty, showed a seasonal change in the diet; Corophi\:un being more important in the summer, and Nereis, feco. lthica,Hydrobia and P. os. io_£l. ans in the autumn and winter.. Changes in dietbetween day and night were relatively unimportant as were the differences between age classes, though the younger fish (0 & X-group) took many Crangon vulgaria, Gammarus sp. and Meomysis integer, whilst Macoma and Hydrobia wore secondarily important to the older age groups. Trapping throughout 24-hour periods showed that the stomachs of flounders were filled over the high tide period on the mudflatsf irrespective of whether high tide occurred by day or night, whereas at low water most fish had empty stomachs. However, variations in stomach fulness at high tide occurred. 0-group flounders had significantly fuller stomachs during the day than by night, but no differences were found in the >I-group. Also to show conclusively that the >I-group fill their guts to the same extent on different tides an index of gut (stomach plus intestine) fulness was determined and found not to vary significantly between day and night.