A mass spectrometer for pain-response monitoring in rats

A mass spectrometer with a membrane interface has been used for measuring the relative concentration of carbon dioxide (CO₂) released from rat skin in response to thermal irritation and pain stimulus during intraperitoneal propofol–lidocaine anesthesia. It is established that the local anesthetic lidocaine directly influences the central nervous system and induces antinociceptive reaction to thermal irritation.     

Calculating the number of actual separation stages in mass transfer columns

is the A method is proposed for calculating the number of actual separation stages (trays) in columns from the given concentration of components in the original mixture and at the ends of the column (in the overhead and bottom products).     

Problems of Locating Acoustic Emission Sources

Russian Journal of Nondestructive Testing - The accuracy of locating acoustic emission (AE) sources in the zones of stress raisers (central holes 5 mm in diameter) located a distance of 40 mm away...     

New trends in the development of dc arc furnaces

New trends in the development of dc arc furnaces, which make it possible to extend their energy and technical capabilities, are considered.     

Investigation of Acoustic Emission in Low-Carbon Steels during Development of Fatigue Cracks

AE control results for cyclic tests of metal samples with a notch are presented. The main stages of the fatigue crack development and standard AE parameters are matched. A criterial plane which allows to separate clusters corresponding to the stages of stable and avalanche-like defect growth has been constructed. It is shown that the boundaries of clusters remain unchanged irrespectively to the differences in the kinetics of damage development.     

Online mass-spectrometric monitoring of O<Subscript>2</Subscript> and CO<Subscript>2</Subscript> during anesthesia

It is suggested to determine the breathing cycle duration during anesthesia by the online method based on synchronous mass-spectrometric monitoring of the concentrations of an inert gas (not involved in metabolism), CO₂, and O₂. Comparative results of determining the temporal boundaries of the breathing cycle using the proposed method with argon (Ar) and krypton (Kr) are presented. The concentrations of CO₂, O₂, and Ar (or Kr) were measured using an electron-impact ionization mass spectrometer. The gas mixture was sampled directly from the breathing circuit of an anesthesia machine during low-flow balanced inhalation anesthesia. The obtained results show the possibility of using mass-spectrometric monitoring of the CO₂/O₂ metabolism in order to assess online the adequacy of anesthesia with respect to surgical invasion during anesthesia.     

Approach to 3-d ultrasound high resolution imaging for mechanically moving large-aperture transducer based upon Fourier transform

A new three-dimensional (3-D) acoustic image formation technique is proposed that is based on the transmission of wide bandwidth pulse signals and the application of the 3-D fast Fourier transform. A solution to the Helmholtz wave equation has been obtained using the Born approximation. The solution contains analytical expressions for the spatial spectra of the transmit and receive radiation patterns for transducers of various geometries with lenses of fixed focal distances. It has been shown that the proposed algorithms allow for radiation patterns with constant widths at depths both behind and in front of the focal point, starting practically from the plane of the transducer. The theoretical and experimental investigations and computer simulation for both spherical and rectangular transducer shapes have been performed. The results were used to estimate the beamwidths and the side lobe levels. A variant of the linear array has been studied for a cylindrical lens of a fixed focal distance moving in a lateral direction. It has been shown that, in this case, a high resolution (of the order of a few wavelengths) can be achieved along all three Cartesian coordinates at a very high scanning velocity. The influence of the moving scatterers' velocity in inhomogeneous medium on the spatial radiation pattern characteristics has been estimated.     

A mass spectrometer with a membrane interface for oil concentration monitoring in seawater

An immersion mass spectrometer with a membrane interface was used for oil detection and oil concentration measurements in seawater by measuring in situ the concentrations of three hydrocarbons: benzene, toluene, and xylene in the region of the specialized Primorsk oil loading seaport in the Gulf of Finland. The recorded mass spectra demonstrated the possibility of measuring the oil concentration in seawater and determining the grade of oil products. The use of a mass spectrometer with a membrane separator interface allows measurements of hydrocarbon concentration with high accuracy, which is currently not provided in commercially available monitors.