Virginia Tech Patents
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- Fastening device(United States Patent and Trademark Office, 1919-05-06)
- Reaction products of esters of polyphosphoric acids and heavy metal oxides and method of making same(United States Patent and Trademark Office, 1951-03-13)
- Antibacterial compositions and methods of using same(United States Patent and Trademark Office, 1963-03-19)
- Apparatus for transferring anaerobic bacteria(United States Patent and Trademark Office, 1972-05-30)An apparatus for transfer of anaerobic bacteria under oxygen-free conditions having at least one pivotally mounted discharge for discharge of an oxygen-free gas downwardly toward a tube support and a discharge for discharge of measured quantities of anaerobic bacteria toward the tube support. The gas discharge can be pivoted to a remote position.
- Anaerobic microbe transport assembly and method of using(United States Patent and Trademark Office, 1976-02-17)Disclosure is made of a novel assembly for transporting anaerobic microbes from clinical patient to laboratory. The assembly provides a convenient and reliable means of maintaining microbial viability in the critical period between collection and deposition in a culturing environment.
- Method and apparatus for automatically injecting the fluid contents of a plurality of pre-loaded syringes into a gas chromatograph or the like(United States Patent and Trademark Office, 1976-08-10)An apparatus for sequentially dispensing the fluid contents of a plurality of pre-loaded syringes is disclosed. A first means sequentially places each of a plurality of pre-loaded syringes in a dispensing position, each syringe being of the type having a syringe needle, a syringe barrel and a syringe plunger. A second means depresses the syringe plunger of each syringe located in the dispensing position so as to dispense the fluid contents of each syringe positioned thereat. The first means also removes from the dispensing position any syringe whose plunger has been depressed.
- Apparatus for breaking bacterial cells(United States Patent and Trademark Office, 1981-10-20)A multiple tube holder is suspended at the upper end on a frame so that the lower end can pivot through a small arc about a horizontal axis adjacent the upper end of the holder. A motor is connected to the lower end of the holder for pivoting the lower end of the holder through said small arc at a rate of approximately 1800 cycles per minute. A tray means is positioned below the holder for supporting a cooling liquid at a controlled temperature so that the lower end of the tubes on the holder will be immersed in the liquid to prevent destruction of proteins and enzymes released during cell breakage.
- Heat flux gage(United States Patent and Trademark Office, 1988-10-25)The invention is a heat flux gage applied to a surface, for the measurement of surface heat transfer. All elements of the gage are thin films, deposited on the surface by sputtering or an equivalent process. The gage comprises a plurality of thermocouple junctions connected as a differential thermopile, with hot and cold junctions on the two faces of a planar thermal resistance element. Electrical insulating and protective layers are deposited between the surface and the gage, and over the exterior of the gage. The gage output signal is a voltage indicative of heat flux.
- Resonant converters with secondary-side resonance(United States Patent and Trademark Office, 1988-11-15)A family of quasi-resonant converters is disclosed as comprising a voltage source, a transformer having primary and secondary windings, and a switch for periodically coupling the voltage source to the primary winding, whereby a charging current appears on the secondary winding. The transformer exhibits a characteristic leakage inductance. A capacitor exhibiting a characteristic capacitance is coupled to the secondary winding to form a resonant circuit including the leakage inductance and the capacitor. The secondary winding is coupled to apply the charging current to the capacitor. A rectifying circuit couples the capacitor to a load, whereby the voltage stored in the capacitor is delivered to the load. The capacitor is directly connected to the secondary winding and to the rectifying circuit to permit positive and negative going voltages to be stored therein, whereby magnetic flux within the core of the transformer is dissipated and the transformer magnetically reset.
- Non-destructive tester for transistors(United States Patent and Trademark Office, 1989-07-25)A non-destructive reverse-bias second breakdown tester for testing semiconductor devices such as transistors and thyristors that have a base-collector-emitter configuration. The tester basically comprises a socket for holding the device under test. A base drive provides a drive current to the base of the device under test. A collector supply provides a collector current to the device under test. A current diverter diverts current away from the device under test when the device under test experiences reverse-bias second breakdown. The diverter includes first, second and third switches arranged in series. A diode diverter is connected to the current supply and the third switch. A detector produces a first signal at the onset of reverse-bias second breakdown in the device under test. In response to the first signal, the first, second and third switches are activated in seriatim. The activation of all of the first, second and third switches causes the current applied to said device under test to be diverted through said diode diverter and the first, second and third switches.
- Modal domain optical fiber sensors(United States Patent and Trademark Office, 1989-08-08)A modal domain optical fiber sensor for vibration monitoring and as a mechanical motion detector. A laser that focuses coherent light through a lens into one end of a multimode optical fiber. The fiber is secured to a mechanical mechanism for exciting vibrations. The other end of the optical fiber passes its output through a spatial filter and into a photodetector. A variable voltage signal from the photodetector is fed to a monitoring unit, such as an oscilloscope or a microcomputer, for analysis. Of particular significance is the intentional mismatch between the wavelength of the light 18 from the laser and the single mode cut-off wavelength of the glass optical fiber. In a preferred embodiment, the optical fiber has a wavelength of 850 nm and the coherent light has a wavelength of 633 mm.
- Zero-voltage-switched multi-resonant converters including the buck and forward type(United States Patent and Trademark Office, 1989-08-15)A multi-resonant-switching network that operates under switching conditions that are favorable to both the active switch and the diode that constitute the switch. In a zero-current multi-resonant switch, the resonant circuit is formed in a T-network with resonant inductors in series with the switching devices. In a zero-voltage multi-resonant switch, the resonant circuit is formed in a .pi.-network with resonant capacitors connected in parallel with the switch. In this way, the two networks are dual. During operation of a multi-resonant converter, a multi-resonant switches forms three different resonant circuits depending on whether the active switch and diode are open or closed. This results in operation of the converter with three different resonant stages in one cycle of operation. In practicing the present invention, certain rules are applied to derive a ZVS-MRC from a PWM converter. In particular, one resonant capacitor is placed in parallel with the active switch, which may be either uni-directional or bi-directional, another resonant capacitor is placed in parallel with the rectifying diode, and an inductor is inserted in the loop containing the switch and the diode. This loop can also contain voltage sources and filter or blocking capacitors. Improvement in the operation of ZVS-MRCs is obtained with synchronous rectification which is achieved by replacing rectifying diodes in a DC/DC converter with active devices, called synchronous rectifiers.
- Half-bridge zero-voltage switched multi-resonant converters(United States Patent and Trademark Office, 1989-08-22)A half-bridge zero-voltage-switched multi-resonant converter. The converter basically comprises a device for converting an input voltage signal to a DC output signal to be imposed across a load. The device includes input terminals for receiving the input signal and output terminals for imposing the DC output signal across the load. Serially connected first and second switching assemblies are connected in parallel across the input terminals. Each of the first and second switching assemblies includes a transistor switch, a diode and a capacitor all arranged in parallel. The device further includes a transformer having a primary winding and serially connected first and second secondary windings. A first rectifier in parallel with a first resonant capacitor is used to connect the first secondary winding across the output terminals. Circuitry is provided for connecting the primary winding of the transformer to the input terminals and to the serial connection between the first and second switching assemblies. In order to complete the zero-voltage-switched multi-resonant converter for off-line use, a resonant circuit is formed with the first and second resonant capacitors and the total inductance of the primary winding of the transformer.
- Method of detecting, isolating and purifying clostridium difficile toxin A and its receptors(United States Patent and Trademark Office, 1989-09-05)A method is provided for detecting the presence of C. difficile toxin A. Stool or other appropriate specimen is contacted with a reagent containing an available non-reducing galactose-alpha-1-3-galactosyl structure, which is a specific receptor for toxin A. The reagent may be intact cells, cell membranes, membrane fractions containing the toxin A receptor structure, glycoconjugates, as well as the purified toxin A receptor per se. Binding of toxin A is determined by conventional assay techniques. The method may also be used to isolate and purify toxin A. Conversely, immobilized toxin A is used to detect, isolate, or purify biological materials of interest containing the receptor structure.
- Multi-loop control for quasi-resonant converters(United States Patent and Trademark Office, 1989-09-12)A multi-loop controller for controlling a quasi-resonant converter having a power switch, a filter inductor and an output voltage. The controller includes a sensor circuit for sensing the output voltage of the converter. A detector monitors the filter inductor current of the converter. The output voltage is compared with a known reference voltage to develop a control error voltage when the output voltage exceeds the reference voltage. A comparing circuit then compares the inductor current with the control error voltage and produces a control signal when a predetermination relationship has been detected. Finally, an activating circuit responsive to the control signal turns the power switch on.
- Antibody for C.difficile(United States Patent and Trademark Office, 1989-11-07)Monoclonal antibody to toxin A of C.difficile has been prepared and is used in an assay for toxin A of C.difficile.
- Preparation of open chain poly(reissert compounds)(United States Patent and Trademark Office, 1990-05-29)An open chain poly Reissert can be formed by the initial reaction of an aromatic dialdehyde (e.g., terephthaldicaboxaldehyde) and primary amine (e.g., methylamine) to form a reaction product which is then reacted with an aliphatic acid chloride (e.g., adipoyl chloride).
- Process for the hydroformulation of olefinically unsaturated organic reactants using a supported aqueous phase catalyst(United States Patent and Trademark Office, 1990-08-07)A process for the hydroformylation of alkenes and other olefinically unsaturated reactants by reaction with carbon monoxide and hydrogen in the presence of a heterogeneous catalyst comprising a solid surface having immobilized thereon a solution of one or more rhodium complexes which is essentially immiscible with the organic reactant. Catalyst is subsequently recovered from the resulting hydroformylation product by one or more solid-liquid separation techniques.
- Novel phosphorus containing epoxy networks(United States Patent and Trademark Office, 1990-11-27)Epoxy resins can be cured or crosslinked with triphenyl phosphine oxide compounds having epoxy-reactive (active hydrogen) substituents either alone or in combination with amine-terminated polyarylene ethers (e.g., amine-terminated polysulfone oligomers or high polymers.
- Reissert compound of bisbenzimidazole(United States Patent and Trademark Office, 1990-12-11)A Reissert compound of bisbenzimidazole can be formed by first reacting benzimidazole with an aliphatic diacid chloride to form bisbenzimidazole and then reacting the bisbenzimidazole with an aliphatic acid chloride and cyanide to form the Reissert compound thereof.