Abstract:
Systems and methods disclosed provide for methods of managing polarity switching in an ion mobility spectrometer, and provide for management of the repelling grid voltage, the gating grid voltage, and the fixed grid voltage during polarity switching. Systems and methods also provide for the management of the effect of dielectric relaxation in an insulator proximal to the collector, and provide for a preamplifier coupled to the collector including a switch, and a method of managing the collector output including the switch. Systems and methods consistent with the current disclosure further provide for a method of normalizing ion mobility data by determining fitting coefficients associated with a plurality of measurement data sets, and subtracting the curves determined by the fitting coefficients from the data acquired by the ion mobility spectrometer.
Abstract:
An apparatus and method for thermally cycling a reaction mixture in a reaction vessel to expose the mixture to the varying temperatures necessary to, for example, achieve PCR amplification or the preparation of sequencing fragments using a cycle sequencing operation makes use of flow-through reaction vessels, such as capillary tubes, for the preparation and thermal cycling of reaction mixtures. In order to prevent loss of the reaction mixture from the vessels during heating, the thermal cycling apparatus of the invention provides means for reversibly sealing the proximal and distal ends of each reaction vessel. The proximal ends can be sealed by coupling to a pump which permits movement of the samples within the reaction vessels. As to the distal ends, the reaction vessels can be sealed by pressing the distal end of each vessel against a sealing element with a conformable surface, or by immersing the distal end of each vessel in the reservoir of liquid, preferably of an oil, that is not miscible with the reaction mixture.
Abstract:
Gel holders for electrophoresis gels are made using clad fibers, particularly glass fibers as spacers between substrates. A plurality of fibers with a high-melting interior core and a low-melting external cladding are placed between a first planar substrate and a second planar substrate. The fibers are heated to a temperatrure sufficient to at least soften the exterior cladding of the fibers without softening the interior core of the fibers, and then cooled while they are in contact with the first and second substrates to resolidify the exterior cladding. This adheres the fibers to the first and second substrates, and forms a gel chamber between said first and second substrates. The gel chamber has a thickness defined by interior core of the fibers. The fibers may be heated before or after the second substrate is placed over the top of the fibers. The gel holders thus formed may be filled immediately with a gel forming solution such as a polyacrylamide, or they may be stored indefinitely and used as needed.
Abstract:
Looped ionization sources for ion mobility spectrometers are described. The ionization sources can be used to ionize molecules from a sample of interest in order to identify the molecules based on the ions. In an implementation, an electrical ionization source includes a wire that is looped between electrical contacts. The wire is used to form a corona responsive to application of voltage between the wire and the walls of an ionization chamber. The corona can form when a sufficient voltage is applied between the wire and the walls. A difference in electrical potential between the wire and a wall forming an ionization chamber, in which wire is contained, can be used to draw the ions away from the wire. In embodiments, the wire can be heated to reduce the voltage used to strike the corona. The ions, subsequently, may ionize the molecules from the sample of interest. The looped corona source can also be used in mass spectrometers (MS).
Abstract:
Gel holders for electrophoresis gels are made using fibers, particularly glass fibers, which are affixed to the substrates forming the gel holder using an adhesive. These gel holders can be made by placing a plurality of adhesive-coated fibers between a first planar substrate and a second planar substrate; and applying pressure to the outside of the substrates to adhere the fibers to the first and second substrates. This forms a gel chamber between the first and second substrates which has a thickness defined by diameter of the fibers. Alternatively, uncoated fibers may be laid down in pairs, with a line of adhesive disposed between each fiber of the pair. When the adhesive is cured, it binds the fibers in position as spacers. At the same time, the fibers isolate the adhesive from the gel compartment. In this way, interference of components of the adhesive with the polymerization of the gel in the gel chamber can be avoided. Gel holders formed using either of these methods may be filled immediately with a gel forming solution such as a polyacrylamide, or they may be stored indefinitely and used as needed.
Abstract:
Looped ionization sources for ion mobility spectrometers are described. The ionization sources can be used to ionize molecules from a sample of interest in order to identify the molecules based on the ions. In an implementation, an electrical ionization source includes a wire that is looped between electrical contacts. The wire is used to form a corona responsive to application of voltage between the wire and the walls of an ionization chamber. The corona can form when a sufficient voltage is applied between the wire and the walls. A difference in electrical potential between the wire and a wall forming an ionization chamber, in which wire is contained, can be used to draw the ions away from the wire. In embodiments, the wire can be heated to reduce the voltage used to strike the corona. The ions, subsequently, may ionize the molecules from the sample of interest. The looped corona source can also be used in mass spectrometers (MS).
Abstract:
An apparatus for processing samples containing DNA to produce a sequencing fragment mixture comprises a sample processing element comprising: a thermocycling region having one or more chambers for receiving a DNA sequencing reaction mixture and forming sequencing fragments therefrom; a separation region comprising a separation matrix for separating the sequencing fragments formed in the thermocycling regions; a detection region for detection of the separated sequencing fragments; and means for regulating the temperature in the thermocycling region of the sample processing element to provide a plurality of thermal cycles, each cycle including at least a denaturation phase and an extension phase. The apparatus for processing sample can be placed in a holder which is associated with means for applying an electric field to the separation region of a sample processing apparatus placed within the holder to cause polynucleotide sequencing fragments to migrate through the separation region from the thermocycling region to the detection region; and means for detecting polynucleotide fragments within the detection region of the sample processing apparatus placed within the holder.
Abstract:
An electrophoresis microgel is formed in a gel holder. The gel holder comprises a top substrate, a bottom substrate and a spacer disposed between the top substrate and the bottom substrate. The spacer establishes a separation of from 25 to 250 microns between the top substrate and the bottom substrate. A gel compartment is formed by partially sealing the top substrate to the bottom substrate, while leaving an opening for the introduction of unpolymerized gel. The gel compartment is then filled with an unpolymerized gel, which is polymerized in the gel compartment. Electrodes may be printed on the substrates, may be contacted to an exposed edge of gel, or may be applied through windows cut into one of the substrates. One type of gel holder makes use of graded beads having a diameter of 25 to 250 microns slurried in an adhesive such as an acrylate adhesive as the spacer. The slurry is printed onto the surface of one or both substrates to form a spacer of the desired shape, and then hardened using heat or light. If desired, the spacer can establish lanes within the gel.
Abstract:
An apparatus for the rapid preparation of electrophoresis gels comprises: a) a housing; b) a support fixture removably disposed within the housing and adapted to receive a gel holder having an internal gel compartment, the support fixture being optionally adapted to permit filling of the gel holder within the housing; c) an optional injection system, which is connectible to a reservoir for holding a polymerizable solution; d) an optional solution connector adapted to couple the injection system to a gel holder placed within the filling fixture; e) an optional controller for the injection system, which causes the injection system to inject polymerizable solution from the reservoir into the gel compartment; and f) a radiation source disposed within the housing in a location effective to irradiate polymerizable solution within the gel compartment of a gel holder in the support fixture. The support fixture may be mounted on a drawer which is slidable between a position inside the housing, and a position outside the housing to permit easy placement of a gel holder into the support fixture.