A device and method for measuring the internal impedance of an electronic sensor uses configurable gain stages to selectively apply different excitation signals to the sensor under test in order to ensure adequate signal-to-noise ratio to provide accurate measurement of the internal impedance over a broader range of internal impedances than the prior art.

In the specification and drawings, an apparatus for conducting hot work is described and shown with an enclosure; a hot work apparatus operable within the enclosure; and a detector located exterior of the enclosure, the detector being in detecting communication with the interior of the enclosure, such that the detector detects the presence of a condition within the enclosure. A method of conducting hot work is also described and shown.

A device housing that is designed to maximize the dwell time for volatile compounds drawn into a cell-based compound detection device is described. The modular functional components of the cell-based detection devices are also described.

A method performed by a system controller and evaluating a manhole event occurring in a duct-manhole system. The method includes estimating a size of the manhole event occurring in the system or estimating relative contributions to a fire of at least two of oxidative decomposition, pyrolysis, plasmatization, and flammable gas accumulation. Optionally, the method may include notifying one or more users and/or altering a rate of atmospheric turnover in the duct-manhole system.

A method for reducing the variability, as measured by relative standard deviation (RSD), of an analytical testing technique is provided. This improvement in RSD improves the confidence in the values obtained during field testing. The method includes incorporating a focusing agent into the sampling media, which permits providing sampling media such as thermal desorption tubes preloaded with the focusing agent.

A method performed by a system controller and estimating a size of a manhole event occurring in a network of manhole vaults interconnected by connections. The method includes obtaining first, second, and third mass flow rates for each of a plurality of gaseous components present in exhaust, fresh air, and event flows, respectively, and estimating the size based on the third mass flow rate obtained for at least one of the gaseous components. The exhaust flow exits a selected vault of the manhole vaults, the fresh air flow enters the selected vault from an external atmosphere, and the event flow originates from the manhole event. The third mass flow rate for each of a portion of the gaseous components is determined by subtracting the second mass flow rate obtained for the gaseous component from the first mass flow rate obtained for the gaseous component.

In the specification and drawings, an apparatus for conducting hot work is described and shown with an enclosure; a hot work apparatus operable within the enclosure; and a detector located exterior of the enclosure, the detector being in detecting communication with the interior of the enclosure, such that the detector detects the presence of a condition within the enclosure. A method of conducting hot work is also described and shown.

A chemiresistive vapor sensor compound for detecting target vapors can comprise a perylene-tetracarboxylic diimide (PTCDI) core according to structure (I): ##STR00001##
where R can be a morphology control group or -A′-D′, A and A′ can be independently a linking group, D and D′ can be independently a strong electron donor which transfers electrons to the PTCDI core sufficient to form an anionic PTCDI radical of the PTCDI core, and R1 to R8 can be independently a side group. A chemiresistive vapor sensor for detection of a target compound can comprise an assembly of nanofibers formed of the chemiresistive sensor compound and a pair of electrodes operatively oriented about the assembly of nanofibers to allow electrical current to pass from a first electrode in the pair of electrodes through the assembly of nanofibers and to a second electrode in the pair of electrodes.

A method to make metal-organic frameworks (MOFs) in which a first aqueous solution of a transition metal salt is mixed with a second aqueous solution of an imidazole or alkyl-substituted imidazole to yield a product solution containing MOF crystals. The MOF crystals are used to fabricate electrodes for electrochemical detection of nitro-aromatic compounds.

A thermal desorption tube for chromatography and mass spectrometry analysis. The thermal desorption tube includes a sorbent and a plurality of focusing agents loaded at known, relative amounts onto the sorbent. Each focusing agent is a compound that chromatographically elutes within a retention time similar to a retention time of a target analyte and has a mass spectrum similar to a mass spectrum of the target analyte. The thermal desorption tube is configured to be further loaded with a sample having the target analyte.