Measurements of atmospheric corona currents have been made for over 100 years to indicate the atmospheric electric field. Corona currents vary substantially, in polarity and in magnitude. The instrument described here uses a sharp point sensor connected to a temperature compensated bi-polar logarithmic current amplifier. Calibrations over a range of currents from ±10 fA to ±3 μA and across ±20 ...

CT demonstration of lower cervical spine detail is often limited by a streak artifact created by the shoulders within the tomographic field of view (Fig. 1). The patient may be instructed to hold the shoulders low; however, this position is difficult to maintain without moving throughout the often lengthy examination. Various methods for achieving optimal CT cervical spine images have been desc...

The measurement of soil carbon dioxide respiration is a means to gauge biological soil fertility. Test methods for respiration employed in the laboratory vary somewhat, and to date the equipment and labor required have somewhat limited more widespread adoption of such methodologies. The purpose of this research is to compare the results of measured soil CO2 respiration using three methods: (1) ...

Laser light scattering (LLS) including the angular dependence of the absolute integrated scattered intensity (StaticLLS) and of the line-widthdistribution (dynamic LLS) has been used to characterize the molecular weight distributions of dextran samples with different branching densities. In the procees of converting a translational diffusion coefficient distribution (G(D)) obtained from the pre...

Typically, s ~ n a l l angle neut ron scat ter ing (SANS) d a t a is normalized t o a n absolut,e scale using secondary s tandards such a s water , polymers, silica gels, o r i rradiated aluminum. Er rors for this l r ~ e t h o d of calibration arise when t h e initial deterrllination or calculation of t h e standard 's scattering cross-section is n o longer valid due t o degrada t ion o r wave...

PolyCarboxylate ether-based superplasticizers (PCEs) are a type of comb-shaped copolymers used as polymeric dispersants in cementitious materials. PCEs have a high degree of dispersity, which limits the suitability of conventional characterization techniques, such as Size Exclusion Chromatography (SEC). Properties of PCEs strongly depend on their molecular structure and a comprehensive characte...

This Application Note describes the development of an immunoprecipitation method in combination with microfluidic on-chip analysis on the Agilent 2100 Bioanalyzer for sensitive, selective and quantitative detection of endogenous β-galactosidase in crude E. coli lysates. The effects of antibody selection and the importance of preclearing steps for sensitive and specific detection of the target p...

The molecular weight (MW) of heparin can be accurately determined by size exclusion chromatography using "universal calibration." A universal calibration curve was constructed for Superose 12 with standard pullulan samples and verified using characterized ficoll fractions. This calibration yielded the correct MW of heparin as determined by light scattering, when the ionic strength of the mobile...

Size Exclusion Chromatography is traditionally carried out in either aqueous or non-polar solvents. A system to present molar mass distributions of polymers using methanol as a mobile phase is presented. This is shown to be a suitable system for determining the molar mass distributions poly(N-isopropylacrylamide)s (PNIPAM); a polymer class that is often difficult to analyze by size exclusion ch...

Chemically synthesized duplex oligodeoxynucleotides having different average numbers of adenine tracts (A6) per helix turn were ligated into multimers and analyzed by electrophoresis on polyacrylamide gels. The magnitude of the anomaly in gel mobility is found to be a quadratic function of the curvature of the DNA molecule. Parameters that describe intrinsic DNA bending, expressed as the tilt a...