The effect of UV-B radiation (280–320 nm) on germination of spores and extension of germ-tubes of
Septoria tritici (two isolates from the U.K., two from Tunisia) and
S. nodorum (two isolates from the ...U.K.) was examined
in vitro. Germination of spores after 48 h incubation was unaffected in both species by 4 h irradiation per 24 h period (UV-B
DNA, 3 kJ m
−2 d
−1), but was inhibited in
S. nodorum by continuous UV-B irradiation (UV-B
DNA, 18 kJ m
−2 d
−1). Germination was unaffected by background white light (400–700 nm) for 16 h per day. After 48 h in the dark, germ-tubes were longest in
S. nodorum (both isolates) and shortest in the two Tunisian isolates of
S. tritici. By comparison with continuous darkness, germ-tube extension in all isolates was strongly inhibited by continuous UV-B. Germ tube extension of the U.K. isolates, but not of the Tunisian isolates, was also inhibited by 4 h UV-B both with a dark background and within a 16 h white light day. The time in the 24 h cycle when germination started, i.e. incubation began, and when exposure to either UV-B radiation or white light occurred, affected the response of the fungi. Differences in sensitivity to UV-B between the
S. tritici isolates suggest that adaptations to different fluxes in contrasting natural environments may occur.
New Limit on Magnetic Monopole Flux Bartelt, J.; Courant, H.; Heller, K. ...
Physical review letters,
02/1983, Letnik:
50, Številka:
9
Journal Article
Recenzirano
Grand unified theories of strong, electromagnetic, and weak interactions predict the existence of very massive magnetically charged particles. The magnetic monopole charge is a multiple of the Dirac ...charge, and the predicted monopole mass is 10 to the 16th GeV. The underground Soudan-1 nucleon decay experiment makes it possible to measure the velocities of slowly moving particles if they can be detected by ionization at a level 0.5 times that of a relativistic muon. If the velocities of the magnetic monopoles are greater than 0.001 c, the monopoles should satisfy the detection requirements. During a live time of 0.41 yr, no candidate for magnetic monopole was observed. The implied 90%-confidence-level limit on the flux of such objects is less than 4.1 x 10 to the -13th per (sq cm sr s) for velocities in the range from 0.001 c to 0.01 c.
Analysis of underground muon events from the direction of Cygnus X-3 shows evidence for large time variability of the flux in addition to the 4.8-h modulation. The data presented have support earlier ...suggestions that high fluxes occur with a 34.1-d cycle. Events measured during high-rate periods show increased statistical support for the hypothesis linking underground muons with this X-ray binary. (Author)
Production of sterigmatocystin by Aspergillus versicolor was stimulated by inorganic phosphate when used in conjunction with citric acid cycle compounds.
Microgard super(TM), a commercially available fermented milk product containing antimicrobial metabolites, was a potent inhibitor for Gram-negative bacteria such as Pseudomonas, Salmonella , and ...Yersinia when 1% concentration was incorporated into agar media. Gram-positive Bacillus cereus, Staphylococcus aureus , and Listeria monocytogenes were insensitive to Microgard super(TM). Blood agar base reversed the antagonistic activity of Microgard super(TM) against Pseudomonas putida compared with plate count agar.
The kinetics of the α—σ isothermal transformation in Fe54Cr46 and Fe52Cr46Sn2 (at%) alloys was studied by magnetization (M) and electrical resistivity (ρ) measurements at constant temperature, T = ...973 K. The variations of the resistivity with temperature during heating or cooling are interpreted in terms of the magnetic and structural evolutions of the alloys. The time dependence of the isothermal increase of ρ and of the decrease of M follows Johnson‐Mehl‐type equations with similar kinetic coefficients. Magnetization and resistivity studies, and also in‐situ transmission electron microscopy investigations, confirm that the presence of Sn retards the α—σ transformation by preventing the σ phase nucleation at grain boundaries.
Les cinétiques de la transformation isotherme de la phase α en phase σ ont été étudiées à T = 973 K pour deux alliages Fe54Cr46 et Fe52Cr46Sn2 (at%) en suivant l'évolution de l'aimantation et de la résistivité en fonction du temps de recuit. Les variations de la résistivité au chauffage et au refroidissement sont expliquées par les évolutions magnétiques et structurales des alliages. L' augmentation de résistivité isotherme et la diminuition de l'aimantation isotherme, ajustées à l'aide d'équations de Johnson‐Mehl, conduisent à des valeurs cohérentes des paramètres cinétiques. Ces mesures et une étude in‐situ de la transformation isotherme par microscopie électronique à transmission confirment que l'étain retarde la transformation α—σ en empéchant la germination de la phase σ aux joints de grains.
PDF
