Wolfhard Wegscheider | Montanuniversität Leoben (original) (raw)

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Papers by Wolfhard Wegscheider

Quintessence: Publicación internacional de odontología, 1989

Se confrontaron cuatro procedimientos alternativos de fabricacion de coronas (Ceplatec, Dicor, Ce... more Se confrontaron cuatro procedimientos alternativos de fabricacion de coronas (Ceplatec, Dicor, Cerestore, Hiceram) de las coronas revestidas de ceramica corrientes con cuatro aleaciones Degudent U, Deva 4, Eco 2000, Sinor C33) y con las coronas jacket y se sometieron a una investigacion de ajustes marginales. Se elaboraron las coronas sobre munones de laton segun tres modos de preparacion (en chaflan biselado, en chaflan y en escalon) y, dado el caso, con y sin estadio ceramico. Los nuevos procedimientos son equivalentes a las ceramicas con metal en cuanto a la precision de la fisura marginal y aventajan claramente a las coronas jacket. Deva 4 y Eco 2000 muestran, de entre las aleaciones, los mejores resultados sin diferencias significativas en cuanto a las diversas formas de preparacion.

Analytical Proceedings, 1994

Journal of Radioanalytical and Nuclear Chemistry, Sep 1, 1980

For the quantitation of overlapping peaks in energy dispersive X-ray fluorescence analysis, a com... more For the quantitation of overlapping peaks in energy dispersive X-ray fluorescence analysis, a computer program has been developped. It is based on a linear least-squares deconvolution of digitally filtered spectra. The performance of five different filters was studied on simulated spectra with respect to systematic and random errors. It is concluded that a symmetric, zero-weighted filter consisting of a Gauss-shape central lobe and a negative constant involving an energy range of 280 eV gives optimal results. The random error introduced by the filtering procedure is very moderate, so that the total error is only slightly above the value predicted from theory. A series of difficult analytical situations (S/Mo; S/Pb; Ti/V/Ba) are treated satisfactorily. Explantations for problems experienced in the literature are suggested.

Proceedings, Nov 19, 2020

Materialwissenschaft Und Werkstofftechnik, Feb 1, 2002

Journal of Chromatography A, Dec 1, 1989

ABSTRACT Optimization of high-performance liquid chromatography for application to a cough medica... more ABSTRACT Optimization of high-performance liquid chromatography for application to a cough medication (Tussagesic) and its decomposition and byproducts was performed. Special emphasis was placed on the optimization of all parameters that relate to the chemical selectivity of the separation process itself and on the final proof of the ruggedness of the optimized system. All analytes can be reliably determined and the response surface can be represented graphically. This provides a means for improved transfer of methods between laboratories and for efficient system documentation.

Accreditation and Quality Assurance, Jan 16, 1996

Elsevier eBooks, 1980

ABSTRACT Sampling, recovery, chemical analysis and characterization of fine ambient urban particu... more ABSTRACT Sampling, recovery, chemical analysis and characterization of fine ambient urban particulate matter which can be found abundantly deposited in filter systems of large scale air conditioning installations will be reported in this paper. Using these non costly sources, sufficient amounts of fine dust material have been collected at several locations in the city of Graz. After recovery, the sieved and homogenized candidate material was prepared for subsequent analysis, employing acid pressure digestion as well as borate glass fusion decomposition. In the course of the development of natural reference materials for fine ambient particulate matter, batches stemming from different sources have been investigated individually and inter-compared, using simultaneous multielement investigation techniques as well as AAS and HPLC. Some inorganic target-compounds including mineralogic major elements and heavy metals trace elements have been determined in addition to a number of well known polycyclic aromatic hydrocarbons. Finally, results of an intercomparison study between seven environmental analytical laboratories are presented, and fundamental requirements for fine particulate standard reference materials are discussed.

International Journal of Environmental Analytical Chemistry, Aug 1, 1978

If environmental analytical chemistry is to be practiced on a routine scale involving a great num... more If environmental analytical chemistry is to be practiced on a routine scale involving a great number of laboratories, certain measures have to be taken to insure the comparability of data; one of these measures is the verification of the results with known materials.In the course of the development of known materials a detailed intermethod comparison of energy dispersive X-ray fluorescence and atomic absorption spectrometry of urban dust samples from three different cities was performedThe agreement of results is satisfactory as the discrepancies between the values produced by the two methods are generally below 10% of the content.Some performance characteristics of the two methods are compared. The experiments were designed to give error estimates for the most likely sources of error including the instrumental error of repetitive measurements (AAS and EDXRF), the decomposition (AAS) and fusing (EDXRF) error, the calibration error (AAS) and the error of the bag-house sampling procedure (EDXRF). It is shown that with a live time of 1000 s the instrument precision of EDXRF is generally better than that of AAS and that the bag-house sampling procedure calls for careful blending of the dust before proceeding with the specification of elemental contents.The analytical results are verified with Fly Ash, SRM 1633, from the National Bureau of Standards.

Accreditation and Quality Assurance, 2000

Accreditation and Quality Assurance, 1996