Christopher J. Chaput

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A novel approach to provide, thermally sensitive neutral solutions based on chitosan/polyol salt combinations is described. These formulations possess a physiological pH and can be held liquid below room temperature for encapsulating living cells and therapeutic proteins; they form monolithic gels at body temperature. When injected in vivo the liquid(More)
The aim of this study was to investigate the physical properties of a chitosan/glycerophosphate (GP) thermosensitive solution which gels at 37 degrees C and evaluate the in vitro release profiles of different model compounds. The gelation rate was dependent on the temperature and on the chitosan deacetylation degree. The solution containing 84%-deacetylated(More)
A new thermogelling chitosan-glycerophosphate system has been recently proposed for biomedical applications such as drug and cell delivery. The objectives of this work were to characterize the effect of steam sterilization on the in vitro and in vivo end performances of the gel and to develop a filtration-based method to assess its sterility. Autoclaving 2%(More)
Galactic cosmic rays consist of primary and secondary particles. Primary cosmic rays are thought to be energized by first order Fermi acceleration processes at supernova shock fronts within our Galaxy. The cosmic rays that eventually reach the Earth from this source are mainly protons and atomic nuclei, but also include electrons. Secondary cosmic rays are(More)
Observations of cosmic-ray electrons and positrons have been made with a new balloon-borne detector, HEAT (the “High-Energy Antimatter Telescope”), first flown in 1994 May from Fort Sumner, NM. We describe the instrumental approach and the data analysis procedures, and we present results from this flight. The measurement has provided a new determination of(More)
In this paper we present the results of two measurements of the cosmic-ray positron fraction as a function of energy, obtained using the High Energy Antimatter Telescope (HEAT) balloon-borne instrument. The first measurement, based on data taken in 1994, yielded results above the geomagnetic cutoff energy of 4.5 GeV. The second measurement permitted(More)
Two measurements of the cosmic-ray positron fraction as a function of energy have been made using the High Energy Antimatter Telescope (HEAT) balloon-borne instrument. The first flight took place from Ft. Sumner, New Mexico in 1994, and yielded results above the geomagnetic cutoff energy of 4.5 GeV. The second flight from Lynn Lake, Manitoba in 1995(More)
We present measurements of the cosmic ray positron fraction from 4.5 { 50 GeV obtained from the rst balloon ight of the High Energy Antimatter Telescope (HEAT). A superconducting magnet spectrometer combined with a transition radiation detector, an electromagnetic calorimeter, and time-of-ight counters were used to achieve powerful hadron rejection at these(More)
The High-Energy Antimatter Telescope (HEAT) instrument has been own successfully by high-altitude balloon in 1994 and 1995, in a connguration optimized for the detection and identiication of cosmic-ray electrons and positrons at energies from about 1 GeV up to 50 GeV and beyond. It consists of a two-coil superconducting magnet and a precision drift-tube(More)