5,442 research outputs found
Lethality or improved growth as a result of interaction in DNA repair double mutants of Aspergillus
Genetic analysis recently identified nine new DNA repair genes of Aspergillus nidulans, musK - musS, which map on several different chromosomes (Käfer 1994, preceding article in this Newsletter). Such mus mutants are sensitive to certain chemical mutagens, but not sensitive or only slightly sensitive to UV and gamma-radiation. To identify epistatic interactions with members of the 4 Uvs groups, double mutants strains were isolated (Käfer and Chae 1994 Curr. Genet. 25:223-232). However, some mus;uvs double mutants could not be analyzed because they grew too poorly or were lethal (showing synthetic enhancement in gene interaction ; Guarente 1993 Trends Genet. 9:362-366). The opposite effect was also found; namely interaction which led to improved recovery and growth (or rescue ) as documented here
Inclusive angular distribution of alpha and Li fragments produced in the Fe-C and Fe-Pb collisions at 1.88 GeV/u
The LS (laboratory system) emission angles theta for 2188 and 298 Li fragments, produced inclusively in relativistic Fe-C and Fe-Pb collisions, have been measured in reference to incident Fe-ion beam tracks nearby in nuclear emulsion. An empirical differential frequency formula, dN(cot theta) = exp (a + b cot theta)d(cot theta) is obtained with the constant b approx. = -0.026 at 1.88 GeV/u, which seems to be independent on the kinds of target nucleus as well as on the kinds of projectile fragments
Predictability of reset switching voltages in unipolar resistance switching
In unipolar resistance switching of NiO capacitors, Joule heating in the
conducting channels should cause a strong nonlinearity in the low resistance
state current-voltage (I-V) curves. Due to the percolating nature of the
conducting channels, the reset current IR, can be scaled to the nonlinear
coefficient Bo of the I-V curves. This scaling relationship can be used to
predict reset voltages, independent of NiO capacitor size; it can also be
applied to TiO2 and FeOy capacitors. Using this relation, we developed an error
correction scheme to provide a clear window for separating reset and set
voltages in memory operations
Magnetic and humidity sensing properties of nanostructured Cu[x]Co[1-x]Fe2O4 synthesized by auto combustion technique
Magnetic nanomaterials (23-43 nm) of CuCoFeO\ (x = 0.0,
0.5 and 1.0) were synthesized by auto combustion method. The crystallite sizes
of these materials were calculated from X-ray diffraction peaks. The band
observed in Fourier transform infrared spectrum near 575 cm in these
samples confirm the presence of ferrite phase. Conductivity measurement shows
the thermal hysteresis and demonstrates the knee points at 475C, 525C
and 500C for copper ferrite, cobalt ferrite and copper-cobalt mixed ferrite
respectively. The hystersis M-H loops for these materials were traced using the
Vibrating Sample Magnetometer (VSM) and indicate a significant increase in the
saturation magnetization (M) and remanence (M) due to the substitution
of Cu ions in cobalt ferrite, while the intrinsic coercivity (H) was
decreasing. Among these ferrites, copper ferrite exhibits highest sensitivity
for humidity.Comment: 12 pages, 7 figure
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