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At least 55 records · Page 3Linked to original sources
PubMed2000

Radiofrequency Gaseous Detection Device.

A radiofrequency gaseous detection device is proposed for use with instruments employing charged particle beams, such as electron microscopes and ion beam technologies, as well as for detection of ionizing radiations as in proportional counters. An alternating (oscillating) electromagnetic field in the radiofrequency range is applied in a gaseous environment of the instrument. Both the frequency and amplitude of oscillation are adjustable. The electron or ion beam interacts with a specimen and releases free electrons in the gas. Similarly, an ionizing radiation source releases free electrons in the gas. The free electrons are acted upon by the alternating electromagnetic field and undergo an oscillatory motion resulting in multiple collisions with the gas molecules, or atoms. At sufficiently low pressures, the oscillating electrons also collide with surrounding walls. These processes result in an amplified electron signal and an amplified photon signal in a controlled discharge. The amplified signals, which are proportional to the initial number of free electrons, are collected by suitable means for further processing and analysis.

Journal Article↗
PubMed1978

Simultaneous blank correction in a turbidimetric continuous flow system for immunochemical quantitation of plasma proteins.

By shortening the reaction time by polymer enhancement, it was possible to introduce a line for automatic blank correction in a turbidimetric continuous flow system. The turbidity resulting from the reaction was measured by a simply constructed photometer, the serum turbidity being subtracted by the reference photoelectric cell and the resulting net signal amplified by means of the recorder's stepwise electronic amplifier. Serum transferrin values obtained by this method correlated well with values obtained by estimating blank in separate runs, and with values given be electroimmune assays.

Autoanalysis↗
PubMed2006

Fully coherent x-ray pulses from a regenerative-amplifier free-electron laser.

We propose and analyze a regenerative-amplifier free-electron laser (FEL) to produce fully coherent, hard x-ray pulses. The method makes use of narrow-bandwidth Bragg crystals to form an x-ray feedback loop around a relatively short undulator. Self-amplified spontaneous emission (SASE) from the leading electron bunch in a bunch train is spectrally filtered by the Bragg reflectors and is brought back to the beginning of the undulator to interact repeatedly with subsequent bunches in the bunch train. The FEL interaction with these short bunches regeneratively amplifies the radiation intensity and broadens its spectrum, allowing for effective transmission of the x rays outside the crystal bandwidth. The spectral brightness of these x-ray pulses is about 2 to 3 orders of magnitude higher than that from a single-pass SASE FEL.

Journal Article↗
PubMed1978

The deaf doctor.

Cardiopulmonary auscultation and considerable difficulty in hearing lecturers are major problems which face prospective deaf medical students. As a result, their opportunities for obtaining a medical degree have been, until recently, severely limited. However, rapid advance in electronics research have now made available to them a suitably amplified electronic stethoscope and a free-field radio transmission system.

Clinical Competence↗
PubMed1998

Chemical amplification: continuous-flow PCR on a chip.

A micromachined chemical amplifier was successfully used to perform the polymerase chain reaction (PCR) in continuous flow at high speed. The device is analogous to an electronic amplifier and relies on the movement of sample through thermostated temperature zones on a glass microchip. Input and output of material (DNA) is continuous, and amplification is independent of input concentration. A 20-cycle PCR amplification of a 176-base pair fragment from the DNA gyrase gene of Neisseria gonorrhoeae was performed at various flow rates, resulting in total reaction times of 90 seconds to 18.7 minutes.

DNA Topoisomerases, Type II↗
PubMed1980

I. Novel capacitative electrode with a wide frequency range for measurements of flash-induced changes of interface potential at the oil-water interface. Mechanical construction and electrical characteristics of the electrode.

The mechanical construction and the electrical properties of a new type of capacitative electrode for the oil-water interface are described. The electrode is designed to detect changes of the interface potential induced by photochemical, photophysical, and photobiological reactions occurring at the interface. The construction is based on capacitative coupling of two aqueous compartments separated by a thin Teflon film. Thereby, the oil-water interface is in horizontal position and the electrode is placed with its planar bottom about 10 micrometer above the interface. A main feature of the electrode is the transparency to visible light which is achieved by having a clear electrolyte solution in the inner compartment of the capacitative electrode. The aqueous subphase and the inner electrolyte are connected with Ag/AgCl electrodes to voltage amplifiers. The capacitative electrode is best operated under open circuit conditions. The frequency range experimentally verified is 500 MHz larger than or equal to 0.03 Hz. The sensitivity is mainly determined by the noise of the electronic amplifiers, typical 50-100 muV.

Electric Conductivity↗
PubMedDate not supplied

[Experience in developing devices for medical use exemplified by the electronic stethophonoendoscope].

The paper describes the use of the expert's error technique to provide evidence and pool medical specifications for an electron amplifying stethophonoendoscope, a medical diagnostic device. It illustrates the impact of variations in amplitude-frequency responses (AFR) on the auscultation properties of the devise. An AFR variation of only 10-12 dB can distort sound perception at auscultation. The results of development of the electron stethophonoendoscope indicate that the correct choice of criteria for expert's estimates allows the device's specifications to be worked out with simultaneous simplification of testing procedures.

Artifacts↗
PubMed1998

[Principles of energy sources of totally implantable hearing aids for inner ear hearing loss].

A fully implantable hearing aid consists of a sound receptor (microphone), an electronic amplifier including active audio-signal processing, an electromechanical transducer (actuator) for stimulating the ear by vibration, and an energy source. The energy source may be either a primary cell or a rechargeable (secondary) cell. As the energy requirements of an implantable hearing aid are dependent on the operating principle of the actuator, the operating principles of electromagnetic and piezoelectric transducers were examined with respect to their relative power consumption. The analysis showed that the energy requirements of an implantable hearing aid are significantly increased when an electromagnetic transducer is used. The power consumption of a piezoelectric transducer was found to be less than that of the electronic components alone. The energy needed to run a fully implantable hearing aid under these conditions would be 38 mWH per day. Primary cells cannot provide the energy needed for a minimum operation time of 5 years (70 WH), and therefore rechargeable cells must be used. A theoretical appraisal was carried out on nickel-cadmium, nickel-metal hydride, and lithium-ion cells to determine their suitability as well as to assess the risks associated with their use in an implant. Safety measures were drawn up from the results. Ni-MH cells were found to be the most suitable for use as an energy source for implantable hearing-aids because they are more robust than Li ion cells and their storage capacity is double that of Ni-Cd cells of similar size.

Cochlear Implants↗