Volume 75, Issue 5, May 2004
Index of content:
75(2004); http://dx.doi.org/10.1063/1.1711151View Description Hide Description
The accuracy of surface stress data obtained by means of bending sample methods depends on the precise knowledge of the biaxial Youngs modulus which enters as a prefactor in the stress calculation formula of Stoney and describes the stiffness of the sample’s material against biaxial deformation. Room temperature values are commonly used for However, is significantly temperature dependent. A second order polynomial fit of this dependence is presented for the benefit of future measurements as well as a correction curve for old data.
Standard-deviation minimization for calibrating the radii of spheres attached to atomic force microscope cantilevers75(2004); http://dx.doi.org/10.1063/1.1710697View Description Hide Description
We describe an efficient method for determining the radii of spheres attached to atomic force microscope(AFM) cantilevers by minimizing the square root of the square error for a segment of circular arc cross-sectional data. The approach we present has benefits: (1) The method fits a function, with two fitting parameters, to a number of data points, rather than calculating the radius based on two points of cross-sectional data, (2) a fit is performed in a common spreadsheet application, using a solving feature, and (3) spheres of diameters 2 to 60 μm were measured to an accuracy of 9% and a precision of 4%.
75(2004); http://dx.doi.org/10.1063/1.1710702View Description Hide Description
A successful imagingsystem has been designed and built for yeast pedigree analysis. The system uses a fiber-optic imaging bundle to recognize single yeast cells. Image processing software has been developed to accurately classify the cells as either budding or not budding a daughter cell. This system is intended to replace the body of a microscope for the detection of budding in a microfluidicsystem.
75(2004); http://dx.doi.org/10.1063/1.1711140View Description Hide Description
A new field-emissionx-rayradiography system based on our design is described. The key component of the system is a triode-type x-ray source with a built-in nanostructured electron source. The electron source is comprised of palladium-induced carbon nanofibers, which continue to field-emit electrons for more than 10 h at with a fluctuation of ±8%. Feedback control of the potential of the electron-extracting electrode, or the gate, reduces the current fluctuation to ±0.5%, but this current regulation does little to improve the image resolution. Our system provides sharp x-rayimages of both biological and nonbiological samples.
Photoconductive generation of short electrical pulses of variable duration using a coplanar waveguide with capacitively coupled ground termination75(2004); http://dx.doi.org/10.1063/1.1711146View Description Hide Description
Short electrical pulses with variable duration are generated by optically exciting a coplanar waveguide that is capacitively connected to a ground termination. The underlying concept is based on the superposition of the original pulse and the reflected one with an opposite sign and a variable round trip delay. By sliding the pump beam along the coplanar waveguide,generation of short electrical pulses with different peak voltages, widths, and signs are demonstrated in a laser-diode-based system.