Abstract:
An instrument and method for ascertaining a viable aerobic microbe count at to employing a two-point calibration curve of tthreshold to TVC for each type of sample. One point on the calibration curve is the x-intercept value (i.e., an estimated or experimental value for the logarithm of the minimum viable aerobic microbe count at commencement of testing (to) in a sample effective for causing the sample to reach tThreshold substantially instantaneously upon commencement of incubation). The other point is ascertained experimentally from a sample having a smaller known viable aerobic microbe count at to.
Abstract:
An instrument and method for ascertaining a viable aerobic microbe count at to employing a two-point calibration curve of tthreshold to TVC for each type of sample. One point on the calibration curve is the x-intercept value (i.e., an estimated or experimental value for the logarithm of the minimum viable aerobic microbe count at commencement of testing (to) in a sample effective for causing the sample to reach tThreshold substantially instantaneously upon commencement of incubation). The other point is ascertained experimentally from a sample having a smaller known viable aerobic microbe count at to.
Abstract:
A method of calibrating a luminescence lifetime sensing instrument 20 and of interrogating a target-analyte long-decay luminescence probe 120 includes measuring and reporting luminescence lifetime of the probe 120 employing excitation radiation filtered to remove emission radiation, or a starting time tstart delayed by a predetermined decay delay time, or delayed by a predetermined growth delay time, or an ending time comprising the time at which luminescence intensity has decayed or risen a predetermined percentage.
Abstract:
A calibration card and method of using the card to calibrate an analytical instrument capable of reading a photoluminescent oxygen probe. The card includes at least (a) a first mass of an oxygen sensitive photoluminescent dye retained within a hermetically sealed space so as to isolate the dye from environmental oxygen, and in fluid communication with an activated metal-air battery whereby any oxygen permeating into the hermetically sealed space is quickly consumed by the battery, and (b) a second mass of an oxygen sensitive photoluminescent dye in fluid communication with the environment whereby the second mass of photoluminescent dye is exposed to an environmental concentration of oxygen.
Abstract:
An oxygen-sensitive probe having reduced cross-sensitivity to humidity and methods of manufacturing and using such probes to measure oxygen concentrations within an enclosed space. The probe includes a thin film of an oxygen-sensitive photoluminescent dye on a first major surface of a microporous wettable polyolefin support layer. The dye is preferably a solid state composition comprising the oxygen-sensitive photoluminescent dye embedded within an oxygen-permeable hydrophobic polymer matrix.
Abstract:
A system and method for providing a destination point with a gas having a selectable known humidity. A gas having an initial relative humidity is alternately directed in accordance with a duty cycle along a wet path effective for humidifying the gas to provide a wet gas, and a dry path effective for either maintaining the initial relative humidity of the gas or dehumidifying the gas to provide a dry gas. The wet and dry gas is blended to produce a blended gas having a selected relative humidity based upon the selected duty cycle.
Abstract:
A humidity control system for an analyte permeation testing instrument. The system includes (i) an analyte permeation testing instrument, (ii) a sensor for sensing a target analyte, (iii) a humidity control chamber, and (iv) a selectively permeable membrane permeable to water vapor and impermeable to the target analyte. The analyte permeation testing instrument defines a testing chamber operable for engaging a test film such that the testing chamber is sealingly separated by the test film into a first cell and a second cell throughout a permeation testing period. The sensor is placed in fluid communication with the first cell. The humidity control chamber is positioned adjacent the first cell and in fluid communication with both a source of gas having a known humidity and the first cell, with the selectively permeable membrane sealingly separating the humidity control chamber from the first cell.
Abstract:
A non-destructive method for testing sealed packages for leakage, particularly packages having a gas-permeable portion and a non-gas-permeable portion, by applying a temporary barrier over the gas-permeable portion, wherein the temporary barrier has two apertures, and enclosing the package in a testing chamber having a carrier gas flowing through it to a detector, and passing a tracer gas through the package interior via the two apertures in the temporary barrier.
Abstract:
A plug for providing a predetermined flow rate of leakage gas from a sealed package for purposes of calibration of gas measurement instruments, the plug having an axial passage therethrough with a threaded interior wall; and a bolt for threading into the plug axial passage, the bolt having an axial passage therethrough, and an insert for insertion into the bolt axial passage, the insert having a predetermined size opening for permitting only a predictable flow of leakage gas through the plug.
Abstract:
An oxygen detection device utilizing a water permeable humidifier and two galvanic cells connected in series gas flow connection, each of the galvanic cells having an anode and cathode; the respective cathodes being connected to a common connection between two load resistors, and the respective anodes being separately connected across one each of the load resistors; the device further having a third galvanic cell in close proximity to a water permeable tube to provide an oxygen getter and humidifier.