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JPC - Journal of Planar Chromatography - Modern TLC
Authors: Mirko Prosek, Luka Milivojevic, Mitja Krizman, and Maja Fir

A new on-line TLC-MS interface, with computer-controlled extraction of substances from selected spots on a TLC or HPTLC plate, has been constructed. The controlled collection of the sample and its programmed injection into the mass spectrometer is the advantage of this type of interface. The interface has been tested and validated with a standard solution of caffeine as test substance. The results were compared with those from a previously established and now routinely used off-line TLC-SPE-APCI-MS extraction procedure.

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Szilágyi, L.: Wavelet-Transform-Based QRS Complex Detection in On-Line Holter Systems. Proc. Joint Conf. BMES-EMBS, Atlanta 1999, p. 271. Wavelet-Transform-Based QRS Complex Detection in On-Line Holter Systems

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exposed to wind disturbances. In this way, neural networks are used to adjust the parameters of the PD controller for the attitude control in an on line manner. This attitude control concerns the roll pitch and yaw angles. Thus, there are three neural

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Abstract  

A neutron generator-based on-line coal analysis system is described, capable of measuring the content of the major and minor elements in coal. The system utilizes reactions produced from fast and themal neutrons, as well as from neutron activation with half lives of seconds or minutes. Characteristic γ-rays, detected with BGO detectors are used for the identification of the various chemical elements. The method for the analysis of the γ-ray spectra is presented, and the measurements of coal density, carbon and sulfur content are shown.

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Abstract  

In chemical processing technology on-line activation methods gain an increasing importance for process monitoring and control. In the paper presented a method is described according to which the different fluorspar contents at various strategic points of a flotation plant are to be determined through neutron activation by 100 μg252 californium. For that purpose, a continuous analytical system for on-stream process control of slurries was designed and constructed. This SUSAC compact facility allows continuous application of the method on an industrial scale.

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Abstract  

A computer program was developed for kinetic evaluations of calorimetric experiments to predict the further reaction run under adiabatic conditions. Kinetic modeling is based on elementary reaction steps whose rate laws form a set of differential equations. For the continuous parameter optimization time-temperature data and their derivatives are used. A special calorimeter of the ACTRON series with safety equipment was applied to investigate the kinetics of chemical reactions and to test kinetic on-line evaluations. In the paper, examples for the reaction of n-propanol with o-chlornitrobenzene and for the alcoholysis of phenyl isocyanate are given.

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Abstract  

A detection system is described for monitoring on-line radioactive process solutions by solid scintillation counting. The system consists of a flow cell with perspex windows coated with the plastic scintillator MeltilexTM. The cell is confined in a chamber welded to a La Calhène container. Thus the detection device is easily attached to, detached from and transported between glove boxes, and the electronic parts and the multiplers can be kept outside the box containment. Using outside coated windows, the detector responds to radiation, using inside coated windows, and particles can be detected. Selective measurements can be carried out by installing a chromatographic column in the detector loop. The detection limits of the cell for Am amount to 4·10–9 g Am/ml for outside coated windows and 10–9 g Am/ml for inside coated windows. windows and 10–9 g Am/ml for inside coated windows.

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provides a new choice for it is a kind of on-line automatic processing technology which combines diffusion, chemical and volume exclusion principle. This technology could provide a sensitive, accurate and rapid determination without using isotope situation

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Abstract  

Coal and mineral processing operations can be controlled more economically if information on process variables is obtained continuously. Much of this information can be provided by nuclear techniques. Recent Australian developments in on-line nuclear gauges are reviewed. Techniques have been developed, field tested and commercialised for the on-line analysis of ash and moisture in coal and for the in-stream determination of solids weight fraction and ash in coal slurries. Techniques are being developed for the on-line analysis of moisture in coke and sulphur in lead sinter feed. As well, techniques are being developed for the bulk analysis of silver, lead and zinc in drill cores.

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Abstract  

Thermal neutron prompt gamma activation analysis (PGNAA) has proven to be a useful tool for the multi-elemental characterization of coal. The use of isotopic neutron sources allows the construction of relatively small irradiation facilities for the on-line analysis of large volume samples. As a first step to an on-line analysis system for process control in a coal blending plant we have developed a facility using a Cf-252 neutron source with an actual strength of 1 mg. This source, which is shielded by layers of high purity lead and paraffin, can be moved to the center of cylindrical sample holders containing up to 150 kg of coal. To avoid background radiation the sample holders are made from polyethylene. The prompt gamma rays emitted from the sample are measured with a 22% high purity germanium detector housed in a special horizontally extended cryostate assembly. The detector is positioned on top of the sample; it is surrounded by a multi-layer decreasing Z-absorber to reduce low energy gamma background. Paraffin loaded with 95% enriched lithium-6-carbonate is used between sample and detector as a gamma window with high absorption for thermal neutrons. Moreover the detector is shielded against background radiation by lead and natural lithiumcarbonate. The data processing system consists of high count-rate analogue electronics including pileup-suppression and a fast data acquisition system, which permits on-line analysis of the collected data. Analysis of several samples of simulated coals as well as Western Germany coals shows a good spectral response of our system for the elements H, C, Al, Si, S, Cl, Ca, Ti and Fe, whereas the sensitivity for N, K and Na is somewhat lower. This means, that the quantitative determination of the above elements will be possible within 20 minutes. Optimization of the system is continued with a stress on analysis time and detection sensitivity.

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