Abstract: A Raman spectroscopy system and method for determining a zero-calibration level. A gas sample chamber is located within a resonant cavity. A light source is located to cause light to be incident on the gas sample, the light resonates in the resonant cavity. Typically, the light source and resonator cavity in conjunction form a laser source which propagates coherent, monochromatic laser light energy through the gas sample. This causes Raman scattering from the gases constituent in the gas sample. The amount of Raman scattered light is measured at detectors along with light due to dark noise inherent in the detectors and glow from the laser source, i.e., light at wavelengths other than the laser light wavelength produced by the laser source. The resonator cavity is obstructed, via a ball inserted into the path of the laser beam for example, to prevent resonance. If the light source and resonant cavity in conjunction form a laser, prevention of resonance causes cessation of lasing.

Abstract: A gas analysis cell having a pressure control system eliminates pressure variations in the gas cell regardless of changes in restriction, gas viscosity and barometric pressure. Since optical alignment through the gas cell is sensitive to gas pressure, maintaining a constant pressure in the gas cell makes the system more stable.

Abstract: A gas analysis cell positioned within an optical resonant cavity in a gas analysis system is disclosed wherein the cell includes a flow of buffer gas which forms a "dam", thereby protecting the optical elements in the analysis system. The analysis cell includes an inlet for introducing a gas sample into the analysis chamber of the cell. Two buffer gas inlet ports, one on each end of the cell, are provided to introduce a flow of buffer gas which is directed past optical elements in the system adjacent the ends of the cell. Two output ports are located at the ends of the analysis chamber to remove the buffer gas and gas sample mixture. The flow of buffer gas acts to confirm the gas sample within the analysis chamber and reduce adverse effects which occur when the gas sample comes in contact with the optical elements of the system.

Abstract: The concentration of multiple polyatomic gases are determined simultaneously by Raman light scattering. The gas sample is placed in a sampling cell and a polarized laser beam is passed through the cell, along a longitudinal axis. A portion of the light scattered by the gas sample is captured and detected by means of multiple collection optics-filter-detector channels. The scattered light exits the gas cell via windows located in the sides of the gas cell and enters the collection channels which are aligned with the cell windows. The cell windows are along the longitudinal axis of the laser beam and gas cell. Light scattered by the gas sample provides signals of both inelastic Raman scattered light and elastic laser scattered light which are directed to the collection channels. The optics of each channel transports the scattered light signals onto a laser line rejection filter where the elastic scattered laser signals are attenuated.

Abstract: The present invention is directed to a subcutaneous peritoneal injection catheter apparatus and methods which minimizes catheter obstruction during use. The apparatus includes a receiving chamber or reservoir having a relatively small internal volume while employing a penetrable membrane and relatively enlarged target surface area. The reservoir is interconnected with the peritoneal cavity by a hollow stem. The penetrable membrane accommodates a hollow needle being inserted into the receiving reservoir and is configurated with a dome-like profile so that the membrane may also be depressed to expel insulin from the receiving reservoir into the peritoneal cavity in a direction generally toward the mesenteric peritoneal membrane.The portion of the apparatus which is in the peritoneal cavity is preferably constructed of, or coated with, a material which is capable of minimizing the adhesion of cells and the growth of bacteria on that portion of the apparatus.

Abstract: A time-release chemical delivery system in which a bioactive compound is attached to a polymeric biodegradable carrier by a hydrolyzable bond is disclosed. The bioactive compound can either be bound directly to the polymer or be attached to the polymer via a spacer group. The composition of the system is particularly effective for delivering medication systemically to a host animal over a prolonged period of time after being surgically implanted or injected subcutaneously. Biodegradable condensation polymers having reactive pendant groups, for example, poly-L-(glutamic acid), or derivatized poly-L-(glutamic acid) are effective as polymeric carriers.