Jean M. Schmidt

Light-induced boron-oxygen defect generation in compensated p-type Czochralski silicon

D.M. is supported by an Australian Research Council QEII Fellowship, L.J.G. acknowledges SenterNovem for support, and B.L. and J.S. acknowledge the support of the German Academic Exchange Service.

Isolation of dolastatins 10–15 from the marine mollusc dolabella auricularia

Abstract A twenty year pursuit of the cell growth inhibitory and antineoplastic constituents of the Western Indian Ocean (Mauritius) sea hare Dolabella auricularia has resulted in the discovery of fifteen structurally unique peptide, cyclopeptide, depsipeptide, and cyclodepsipeptide type-substances designated dolastatins 1–15. Solution of the difficult isolation problems leading to discovery of dolastatins 10–15 in 10−6 to 10−7% yields required 1,600 kg of Dolabella aurlcularia. To date, this represents the largest scale separation of sea hare components. Of these dolastatin 10 (4) has displayed unprecedented potency in experimental antineoplastic and tubulin assembly systems. Dolastatin 15 (9), and to a lesser extent dolastatin 14 (8) were also found to exhibit unusually strong antineoplastic activity. Both dolastatina 10 and 15 are in advanced preclinical development. Details of the isolation strategies and structural summaries for dolastatins 10–15 have been recorded. Intensive Study of the cell growth inhibition and antineoplastic constituents of the sea hare Dolabella auricularia provided the structurally unique peptides designated dolastatins 1-15.

Antineoplastic agents 338. The cancer cell growth inhibitory. Constituents of Terminalia arjuna (Combretaceae)

By means of bioassay-guided separation methods, the cancer cell growth inhibitory constituents residing in the bark, stem and leaves of the Mauritius medicinal plant Terminalia arjuna (Combretaceae) were examined. The cancer cell line active components were found to be gallic acid, ethyl gallate, and the flavone luteolin. Only gallic acid was previously known to occur in this plant. Luteolin has a well established record of inhibiting various cancer cell lines and may account for most of the rationale underlying the use of T. arjuna in traditional cancer treatments. Luteolin was also found to exhibit specific activity against the pathogenic bacterium Neisseria gonorrhoeae.

Pasteuria nishizawae sp. nov., a mycelial and endospore-forming bacterium parasitic on cyst nematodes of genera Heterodera and Globodera

This study describes Pasteuria nishizawae sp. nov., a fourth species of the genus Pasteuria. This mycelial and endospore-forming bacterium parasitizes the adult females of cyst-forming nematodes in the genera Heterodera and Globodera. The distinct ultrastructural features and unique host range found for this bacterium separate it from two closely related species, Pasteuria penetrans, which parasitizes several species of root-knot nematodes of the genus Meloidogyne, and Pasteuria thornei, which appears to parasitize only one species of the root-lesion nematode, Pratylenchus brachyurus. Because these obligate bacterial parasites of nematodes have not been cultured axenically, the taxonomic relationships described here for each species are based mainly on developmental morphology, fine structure of the respective sporangia and endospores, and their pathogenicity on nematode species.

Isolation and structure of the cancer cell growth inhibitor dictyostatin 1

Dictyostatin 1 2, a new type of macrocyclic lactone bearing a 22-membered ring system, has been isolated (3.4 × 10–7% yield) from a Republic of Maldives marine sponge in the genus Spongia and found to strongly inhibit growth of the murine P388 lymphocytic leukaemia.

Electron and hole mobility reduction and Hall factor in phosphorus-compensated p-type silicon

This work was supported by the Australian Research Council ARC and by the DAAD/Go8 researcher exchange funding scheme.

Isolation and structure of bryostatins 14 and 15

Abstract Further investigation of constituents from the marine bryozoan Bugula neritina employing new 1,000 kg recollections from the Gulf of Mexico and Eastern Pacific Ocean (California) has led to isolation and structural determination of two previously undetected members of the bryostatin (1-13) series, bryostatins 14 (14) and 15 (15). Structural analyses were conducted primarily with high field (400 MHz) NMR and high resolution mass spectral techniques. Both new bryostatins significantly inhibited growth of the P388 lymphocytic leukemia.

Lifetime-degrading boron-oxygen centres in p-type and n-type compensated silicon

Degradation of minority carrier lifetime under illumination occurs in boron-containing Czochralski silicon of both p- and n-type. In n-Si, the recombination centre responsible for degradation is found to be identical to the fast-stage centre (FRC) known for p-Si, where it is produced at a rate proportional to the squared hole concentration, p2. Holes in n-Si are the excess minority carriers—of a relatively low concentration; hence, the time scale of FRC generation is increased by several orders of magnitude when compared to p-Si. The degradation kinetics, which is non-linear, due to dependence of p on the current concentration of FRC, is well reproduced by simulations. The injection level dependence of the lifetime shows that FRC exists in 3 charge states (− 1, 0, + 1) possessing 2 energy levels. Comparison of n-Si samples of various electron concentrations shows that FRC emerges by the reconstruction of a latent BsO2 complex of a substitutional boron and an oxygen dimer (while the major recombination cen...

ISOLATION AND CHARACTERIZATION OF BACTERIOPHAGES ACTIVE AGAINST STALKED BACTERIA.

The isolation and properties of 23 phages lytic for stalked bacteria of the genera Caulobacter and Asticcacaulis are described. They fall into seven groups on the basis of host range and serological properties. Phages of groups I-VI attack only Caulobacter species; those of group VII, only Asticcacaulis. Groups I-III comprise DNA viruses with long flexible tails and of unusually large size, the heads having dimensions of 50 x 170 mμ. Groups IV-VI comprise RNA viruses of simple structure, 21-23 mμ in diameter. The specific Asticcacaulis phages (group VII) are tailed DNA viruses, similar in form and size to coliphage lambda. The implications of this study for the taxonomy of the caulobacters are discussed.

Influence of net doping, excess carrier density and annealing on the boron oxygen related defect density in compensated n-type silicon

In this study, we present experimental data regarding the concentration of the boron-oxygen complex in compensated n-type silicon when subjected to illumination. We find that the defect density is independent of the net dopant concentration and is strongly dependent on the minority carrier concentration during illumination. We show that annealing at temperatures in the range 500 � C to 700 � C permanently reduces the defect density possibly via a decrease in the oxygen dimer concentration. V C 2011 American Institute of Physics. [doi:10.1063/1.3633492]