Influence of anvil supports and overhangs in dynamic analysis of three point bend testing

Optimum design of dynamic fracture test rigs demands a thorough appreciation of beam vibration under impact. Analyses invariably presume rigid anvils, and neglect overhang effects. The beam response predicted analytically and numerically in this paper highlights the significant role of anvil rigidity and beam overhangs on the impact dynamics of three point bend (3PB) specimens.

Pulsed laser deposition of strontium titanate thin films for dynamic random access memory applications

Polycrystalline strontium titanate (SrTiO3) films were prepared by a pulsed laser deposition technique on p-type silicon and platinum-coated silicon substrates. The films exhibited good structural and dielectric properties which were sensitive to the processing conditions. The small signal dielectric constant and dissipation factor at a frequency of 100 kHz were about 225 and 0.03 respectively. The capacitance-voltage (C-V) characteristics in metal-insulator-semiconductor structures exhibited anomalous frequency dispersion behavior and a hysteresis effect. The hysteresis in the C-V curve was found to be about 1 V and of a charge injection type. The density of interface states was about 1.79 x 10(12) cm(-2). The charge storage density was found to be 40 fC mu m(-2) at an applied electric field of 200 kV cm(-1). Studies on current-voltage characteristics indicated an ohmic nature at lower voltages and space charge conduction at higher voltages. The films also exhibited excellent time-dependent dielectric breakdown behavior.

The level of sequestered calcium in vegetative amoebae of Dictyostelium discoideum can predict post-aggregative cell fate

When freshly starved amoebae of Dictyostelium discoideum are stained with chlortetracycline (CTC), a cell type-specific fluorescent probe for membrane-associated calcium (Ca2+) the resulting fluorescence distribution falls into two functional classes. Fluorescence-activated cell sorting shows that highly fluorescing amoebae tend to enter the prestalk pathway while those with low fluorescence tend to become prespores. In the light of previous findings, these results indicate that in addition to cell cycle phase at starvation, phenotypic variation in the level of sequestered calcium is an early correlate of cell fate.