Abstract: A biochemical sensor includes a material that nucleates as bubbles on the surface of an electrical conductor, optical fiber, or acoustic medium. The nucleating bubbles respectively change the conductivity, refraction, or propagation of such surfaces according to the concentration of the analyte in a solution over the sensor.

Abstract: A rapid, non-destructive process for screening individual photosynthetic clonal colonies for selected gas producing capacity. Gas produced upon illumination of discrete algal clonal colonies grown on solid growth medium is continuously swept away in a carrier gas stream and conveyed to gas detectors for analysis. Hydrogen producing algal clones with enhanced gas production capacities and sustained production may be identified.

Abstract: An instrument and a sealable vessel for detecting the presence of microorganisms in a specimen, the vessel containing a liquid culture medium communicating with a sensor means containing an indicator medium therein. Changes in the indicator medium resulting from pH change or change in CO.sub.2 concentration in the medium are detected from outside the vessel.

Abstract: Gas-generating or absorbing activity of microorganisms is detected by providing a vessel in which the microorganisms are incubated, the vessel having a cap with a membrane indicator therein. The membrane has a deformed region which is inflated to indicate the existence of a change in pressure within the vessel as compared with ambient pressure. Automatic monitoring of the inflated portion is disclosed.

Abstract: A method of testing for the growth of bacteria in a sample comprises introducing the sample into a sterile bacterial growth medium in a closed vessel incubating the vessel, and observing a pressure change within the vessel which indicates the growth of bacteria in the sample. A device for doing this comprises a bottle 10 with a pierceable closure 12; and a syringe comprising a cylinder 16 and a piston 18 connected to a hypodermic needle 20 which passes through the closure 12 and preferably extends below the surface of the growth medium in the bottle.

Abstract: A method of estimating a cumulative exposure to a component of a gas which comprises contacting a liquid reagent held by surface tension in a reservoir with a body of the gas through a conduit into which substantially only diffusional migration of the component from the body of gas occurs.

Abstract: Apparatus and method for generating an anaerobic or microaerophlic atmosphere. A package consisting of a foil envelope has internal compartments for a hydrogen generating material, for a catalyst and for receiving water. The catalyst compartment is provided with a flash arrestor. Water, on being added to the envelope, reacts with the hydrogen generating material. The liberated hydrogen then reacts catalytically with oxygen in the atmosphere external to the package.

Abstract: An apparatus and method for the detection of the growth of microorganisms through infrared analysis of a sample of the gas produced by growth of the microorganism is descirbed. In the method, a sample of the headspace gas in a vial containing a growth medium which has been inoculated with a sample suspected of containing a microorganism is removed and transferred to a sample cell where infrared analysis is used to determine the presence of carbon dioxide, if any, produced by the growth of the microorganism.

Abstract: A method of determining the amount of nutriment absorbed in living organisms comprising animals, fish and plants comprises adding to the animal, fish or plant food one or more elements from the lanthanide series as tracers. After the nutriment has been absorbed, a sample is taken from a localized part of the living organism, for example a fish scale, and the sample is analyzed by ICP (inductively coupled plasma) to determine the amount of tracer and thus the amount of absorbed nutriment in the living organism.

Abstract: The invention provides new redox indicators and uses for these redox compounds (I): ##STR1## Wherein X is oxygen or sulphur, R.sub.1 is julolidine or tetrahydroquinoline, which can carry an alkyl radical on the nitrogen atom which, in turn, can be substituted by a sulphuric, phosphonic or carboxylic acid residues, or is (II); wherein R.sub.4 is hydroxyl or a mono- or dialkylated amino group, R.sub.5 and R.sub.6, which can be the same or different, are hydrogen, alkyl or alkoxy, R.sub.2 is hydrogen or alkyl, julolidine or tetrahydroquinoline, which can carry an alkyl on the nitrogen atom which alkyl can be substituted by sulphuric, phosphonic or carboxylic acids, or is III; wherein R.sub.5 and R.sub.6 are the same as in R.sub.1 and R'.sub.4 is hydroxyl, an amino or a mono-or dialkylated amino group, whereby the alkyl radicals can be substituted one or more times by hydroxyl, alkoxy, halogen, morpholine or a sulphuric, carboxylic or phosphonic acid residue, which acids can also be esterified, and R.sub.

Abstract: Gas-generating activity of microorganisms is detected by providing a vessel in which the microorganisms are incubated, the vessel having a cap with a membrane indicator therein. The membrane has a deformed region which is inflated to indicate the existence of an increase in pressure within the vessel as compared with ambient pressure. Visual or automatic monitoring of the inflated portion is disclosed.

Abstract: A device is adapted for containing a volume of growth medium and employed for detection of gas produced by a microorganism or microorganisms putatively contained within a test sample and added to the growth medium, comprising a primary chamber, a dome defined by the top surface of the primary chamber and communicating therewith, the dome establishing a fluid level and adapted for collection of gas produced by a microorganism within the growth medium, and a fill section adjacent to and communicating with one end of the primary chamber, the fill section spaced apart from the dome and extending above the fluid level, and further defining an opening for the addition of a test sample. The device may be sealed by means of a removable closure. An apparatus also consists of an array of substantially identical devices is also disclosed.

Abstract: An oxygen detector for detecting the presence of trace levels of oxygen in an anaerobic environment consisting of a sample chamber wherein a sample from the anaerobic environment is exposed to a catalyst, such as palladium, which promotes the exothermic chemical reaction of oxygen with hydrogen. The presence of oxygen will cause such reaction to occur on the catalyst and the consequent generation of heat. A thermistor which is in thermal proximity to the catalyst detects this heat and provides a signal. The sampling chamber is enclosed by an enclosure which serves to volumetrically and thermally confine the sample during the measurement thereby enabling small levels of exothermic heat of reaction to be detected. Entrance to the sampling chamber is through a membrane which is permeable to lower molecular weight gases such as oxygen and hydrogen which thus enables diffusion of the anaerobic atmosphere into the chamber.

Abstract: Mixtures of saturated or unsaturated C.sub.2 -C.sub.5 hydrocarbons are produced by aerobically cultivating a microorganism belonging to a wide variety of genera Fungi, Yeasts, Bacteria and Actinomycetes in a water-containing medium, and recovering the hydrocarbon mixtures from the liquid phase or/and gaseous ambience of the medium. Industrial wastes and various biomass can be employed as nutrient sources in the cultivation.

Abstract: A method and an apparatus for controlling the concentration of oxygen and pH of a medium during a bioreaction process in a vessel. The method and apparatus are particularly adapted to a fermentation process. A dissolved oxygen sensor generates a signal corresponding to the pH of the medium and a dissolved oxygen sensor generates a signal corresponding to the dissolved oxygen in the medium. A valve mechanism selectively applies air, N.sub.2, O.sub.2 and CO.sub.2 to the medium. A controller produces a control signal for controlling the operation of the valve means so that a substantially fixed volume of gas consisting of one or more of air, CO.sub.2, N.sub.2 and O.sub.2 are added to the fermenting medium during a period of time. The controller determines in response to the dissolved oxygen and pH signals, the amount of CO.sub.2, O.sub.2 and/or N.sub.2 required to effect dissolved oxygen and pH correction. The controller further adjusts these determined values to compensate for the displacement of the CO.sub.

Abstract: A method for measuring the alcohol concentration of an acetic acid fermentation broth which comprises (a) forming a sample gas containing volatile components present in the acetic acid fermentation broth, the volatile componentscomprising alcohol and acetic acid; (b) passing the sample gas through an absorption column packed with a material which binds acetic acid whereby the acetic acid is absorbed on the material; (c) passing the sample gas which has passed through the absorption column to a gas sensor for measuring the alcohol content of the gas by outputting an electrical signal which correlates to the alcohol content of the sample gas; and (d) determining the alcohol content of the sample gas in response to the electrical output signal from the gas sensor.

Abstract: At the conclusion of a selective binding assay (e.g., immunological or nucleic acid), an enzyme is present in modulated concentration and/or activity to moderate a chemical reaction such as the cleavage of o-nitrophenyl-.beta.-D-galactopyranoside. After a controlled period, the enzymatic product is transferred to the gas phase and concentrated relative to other components in the enzymatic reaction mixture, such as by extraction into ethyl ether, injection into a gas chromatography column and detection by flame ionization or electron capture. Kits for such assays are also disclosed.

Abstract: A system is disclosed for measuring the oxygen concentration in a fluid contained in a fermentation vessel, comprising a fermentation vessel containing a nozzle aperture disposed in the wall thereof, an electrode holder slidably disposed within the nozzle aperture, the electrode holder being provided at one end thereof with an oxygen permeable membrane which provides a wall across the aperture in the vessel for contact with the fluid to be examined, a diaphragm oxygen electrode mounted in the electrode holder of the fermentation vessel so that the diaphragm of the electrode and the oxygen permeable membrane are in close contact with each other, whereby the oxygen concentration of the fluid contained in the fermentation vessel is measured. A method for measuring the oxygen concentration in a fluid contained in a fermentation vessel is also disclosed.

Abstract: A pyroelectric substrate is provided with a heater and at least one set of electrodes for sensing charge redistributions due to changes in the substrate temperature. In a preferred embodiment, there are two interdigitated electrodes, one coated with an absorber/desorber material. The heater pulsatingly raises the temperature of the substrate past the desorption temperature of a fluid of interest. If the fluid was exposed to the absorber/desorber material prior to heating, a portion of the fluid will have been absorbed. When the substrate reaches the desorption temperature, additional heat pulses will not increase the substrate temperature significantly until the fluid has desorbed. Thus, heat used in changing state does not raise the substrate temperature and, lacking a temperature change, reduces the charge redistribution sensed by the electrode coated with the material.

Abstract: An integral multilayer analytical element for the analysis of ammonia or an ammonia forming substrate in a liquid sample is disclosed. The element comprises a transparent support on which an indicator layer for ammonia, a liquid blocking layer, a reagent layer incorporated with a reagent which may react with the substrate to form ammonia, and a spreading layer, are integrally superposed in this order. The improvement is that the liquid blocking layer is made of a porous material which is permeable to ammonia but substantially impermeable to liquids.

Abstract: The disclosed methods and devices for detecting or monitoring or identifying substances (such as chemical warfare agents) and residual environmental pollutants (such as pesticides) utilize the discovery that spectra (e.g. infrared absorption spectra) of an uninhibited enzyme (e.g., a cholinesterase) can differ from spectra of the same enzyme which has been complexed with the agent pollutant. For example, the infrared spectrum of uninhibited butyrylcholinesterase (BuChE) lacks a distinct absorption peak found at about 1000 cm.sup.-1 in the BuChE-Malathion spectrum. The enzyme is used to collect and concentrate the agent or pollutant, and the resulting complexed enzyme can then be analyzed (e.g., by infrared spectroscopy) and its spectrum compared to an uninhibited enzyme spectrum.

Abstract: A method and apparatus are disclosed for determining the concentration of coliform bacteria in a sample. The sample containing the coliform bacteria is cultured in a liquid growth medium. The cultured bacteria produce hydrogen and the hydrogen is vented to a second cell containing a buffer solution in which the hydrogen dissolves. By measuring the potential change in the buffer solution caused by the hydrogen, as a function of time, the initial concentration of bacteria in the sample is determined. Alternatively, the potential change in the buffer solution can be compared with the potential change in the liquid growth medium to verify that the potential change in the liquid growth medium is produced primarily by the hydrogen gas produced by the coliform bacteria.

Abstract: An improved micromethod for the quantitative determination of endotoxins with Limulus Amebocyte Lysate (L.A.L.) reagent is based on the discovery that if L.A.L. reagent and a sample containing microquantities of endotoxin are incubated in a capillary tube, a clot will be formed in the plug preventing any outflow of liquids when low hydrostatic pressure is applied. Increasing the pressure will eventually force out the clot plugging the capillary and the liquid will suddenly erupt giving a clear yes-no indication of the presence of endotoxin. The hydrostatic pressure indicated to cause this eruption is a relatively precise indication of the extent of clotting which, in turn, is indicative of the concentration of endotoxin in the liquid. A kit which can be used to perform this test is also disclosed.

Abstract: A submersible recording respirometer includes an oxygen analyzer which measures the concentration of oxygen absorbed by a wastewater sample contained in an aeration chamber. The aeration chamber forms part of a housing which is submerged in the main body of wastewater and the aeration chamber is periodically drained, washed with fresh water and refilled with another wastewater sample. This cycle is accomplished automatically under the direction of a microprocessor-based control circuit which generates signals to a chart recorder that provides a hard copy of the measurement results.

Abstract: Apparatus for automatically measuring changes in amount of gas comprises a pressure sensor being attached to a closed vessel having a main chamber in which is contained a liquid enzyme or the like and adapted to convert a change in pressure within said vessel into an electric signal and output a measured pressure value signal; a photoelectric sensor adapted to convert an optical change of the liquid enzyme or the like within said closed vessel into an electric signal and output an optical measured value signal; an electrode adapted to come into contact with the liquid enzyme or the like within the vessel to convert a change in conductivity into an electric signal and output a measured conductivity signal; and an arithmetic circuit adapted to input respectively said measured pressure value signal, the measured pressure value signal and said optical measured value signal, and the measured pressure value signal and said measured conductivity signal simultaneously, effect calculations simultaneously in parallel a

Abstract: A simple and functional apparatus is disclosed for use in the home, field and other places in which water or other fluids can be evaluated for the presence of bacteria. Also disclosed is a convenient tablet reagent for use with liquid peroxide with the apparatus.

Abstract: A method of screening a material for potential carcinogenic or mutagenic activity. A mutant stain of eucaryotic or prokaryotic test organism is provided which is capable of reverting to a normal form in the presence of a carcinogen or mutagen. A growth media is provided in which the test organism is capable of growth in one only of its mutant forms. For example, the test organism may be a bacteria which in its mutant form is incapable of substantial growth in the absence of an essential nutrient and, in its natural form, is capable of rapid growth in the absence of that nutrient. The test organism and growth media are combined with oxygen and a material to be screened. Oxygen consumption is then detected to determine if the mutant strain has reverted to its normal form. Reversion is indicated if a change in oxygen consumption occurs when the material being screened is present.

Abstract: A measuring ultrasonic wave transmitter comprises a negative immitance converter inserted between an ultrasonic transmitting transducer and a drive amplifier for driving the transmitting transducer. The output impedance of the drive amplifier, the damping impedance of the transmitting transducer and the impedance between the transmitting transducer and the drive amplifier are offset by the negative impedance caused by the negative immitance converter. A measuring ultrasonic wave receiver comprises a negative immitance converter inserted between a receiving transducer and a pre-amplifier for amplifying the output of the receiving transducer. The damping admittance of the receiving transducer and the load admittance of the receiving transducer are offset by the negative admittance caused by the negative immitance converter.

Abstract: A method and apparatus is provided for determining the concentration or quantity of enzyme molecules, microorganisms or substrate molecules by monitoring directly the concentration and/or the quantity of vaporous by-product produced from the selective reaction of the molecule catalyzed with a known amount of substrate or of an enzyme or a microorganism. The apparatus comprises a membrane permeable to the vaporous product or substrate, a known amount of microorganism or an enzyme adjacent to the membrane, means for introducing a liquid sample into contact with the microorganism or enzyme within a small volume adjacent the membrane and means for measuring the amount of vaporous by-product passing through the membrane. A mass spectrometer located adjacent the membrane surface is suitable for measuring the amount of vaporous product or substrate passing through the membrane.