Reference Data Bank Research Articles

Classification of medieval ceramics in the Rhineland and neighbouring areas by neutron activation analysis

Instrumental neutron activation analysis (INAA) is known to be well suited for provenance determinations of ceramics, since more than 25 minor and trace elements can be measured with precisions high enough to discriminate between different pottery production workshops. INAA-data are presented for more than 1500 shards, mostly wasters, produced in different places such as Bruggen/Elmpt, Brunssum/Schinveld, Frechen/Cologne, Hohr-Grenzhausen, Mayen, Paffrath, Pingsdorf/Bruhl, Raeren and Siegburg, to name only the most important earthen and stoneware production centres of the Rhine area in medieval and post medieval times. It turned out, that the wares of these different centres, although by archaeological criteria often very similar, can be clearly recognized by INAA. This large reference databank can now be used to determine export pieces from these centres and to trace trade relations in the Middle Ages. An example of a provenance determination of questionable finds of Pingsdorf and Paffrath Ware from Emden is given.

Thallium in French agrosystems—I. Thallium contents in arable soils

The thallium (Tl) content of the upper horizons of 244 French soils was determined as the first step towards the creation of a reference data bank for total Tl content of arable soils. Forty soil samples were collected in the vicinity of potential anthropogenic sources of Tl, but the remainder came from rural areas. The distribution of Tl concentrations in soils was characterized by a median value of 0.29 mg Tl kg −1 and a 90th percentile value of 1.54 mg Tl kg −1. Very high pedogeochemical contents were found (up to 55 mg Tl kg −1) but none could be attributed to obvious anthropogenic pollution. Areas of very high Tl concentration belong to an epihercynian transgression zone with a contact between a sedimentary basin and a crystalline massif. This contact is associated with stratified mineralizations (Zn, Pb, F, Sb, Ba, Tl and pyrites). High Tl concentrations were common in limestone, marl or granite derived soils, and the Tl in limestones or marls is probably concentrated in the sulfides contained in these rocks because Tl has a high affinity to S. In granites, Tl may be in the micas and feldspars because Tl + can replace K + in these minerals. Silty or clay-silty soils showed the highest concentrations. These granulometric fractions contain the majority of the minerals, which are supposed to be the major hosts of Tl in soils, i.e. clay minerals, oxides and micas. Tl in the soils was positively correlated with Ba, V, Pb, Fe, Ni, Cd, Zn, Co, As and especially Mn. A significant proportion of Tl may be in the Mn oxides: in oxidizing conditions, Tl(III) could enter the Mn oxides by sorption, or Tl(I) could replace K(I) in the oxide.

Can the assignment of university chairs be automated?

In order to explore the possibility that the assignment of University chairs could be automated, we have carried out a comparative analysis of the relative scientific and technological level of candidates competing nationally for given chairs of first (full professor) and second (associate professor) level, using indicators such as the number of publications and citations in international journals, the number of patents and inventions and few others. This study, contrary to some gloomy opinions, has suggested that at least for what concerns hard science, performances can be measured impartially at least to some extent. Bibliometric indicators, when properly weighted., appear to be effective parameters to monitor degree of excellence in scholastic rating and to establish reliable objective standards. Their utilization, however, to automate the assignment of university chairs appears still questionable and should be limited to the needed provision of computer-assisted selection criteria and reference databank.

Experiences with a reference directory for the perioperative care of children with rare diseases

SummaryA computerized reference data bank for the anaesthetic management and postoperative care of children with syndromes and rare disorders was established two years ago. It contains data on some 2000 syndromes and rare diseases. Updating of the directory is done by regular review of the literature and dialogue with the users. Between January 1991 and January 1993 this interdisciplinary service received 169 telephone, fax or postal calls for advisory service from physicians of all specialities connected with the field of operative paediatrics. The consultations concerned 79 patients with dysmorphias, 58 infants with metabolic disorders and 32 patients with complex or unclassified syndromes. About 58% of the patients were aged under three years. Although the structure of the data bank allows for an advisory service tailored to the individual needs, only 63% of the consultations could be given based upon published anaesthetic experiences of similiar cases. In the absence of anaesthetic case reports, advice for the other cases had to derived from the principles of general paediatric anaesthesia practice. In only 48 of the consultations (28%) was the user's experience reported and could then be stored in the directory.

Eye irritation: Reference chemicals data bank

A list of 55 chemicals has been developed for which comprehensive in vivo rabbit eye irritation data are available. No new in vivo testing has been carried out to qualify a chemical for inclusion in the list. The 55 chemicals selected are available at high and consistent purity and are expected to be stable on storage. They have been tested undiluted in in vivo studies, except those chemicals where high concentrations of the substance could be expected to cause severe effects. The in vivo data have been generated since 1981 in studies carried out according to OECD Test Guideline 405 and following the principles of Good Laboratory Practice. The data were obtained from tests normally using at least three rabbits evaluated at the same time, involving instillation of 0.1 ml (or equivalent weight) into the conjunctival sac, and in which observations were made at least at 24, 48 and 72 hr after instillation. The chemicals represent a range of chemical classes (acetates, acids, alcohols, alkalis, aromatics, hydrocarbons, inorganics and surfactants) and different degrees of irritancy. They are ranked for eye irritation potential on the basis of a ‘modified maximum average score’. The reference data bank should be of use in validation tests for promising alternatives to the in vivo rabbit eye irritation test. This is an essential step in the progression to regulatory acceptance of alternative procedures.

Quantitative AES and XPS: Determination of the electron spectrometer transmission function and the detector sensitivity energy dependencies for the production of true electron emission spectra in AES and XPS

AbstractFor the use of published general or theoretical sensitivity factors in quantitative AES and XPS, the energy dependence of both the spectrometer transmission function and the detector sensitivity must be known. Here, we develop simple procedures that allow these dependencies to be determined experimentally. Detailed measurements for a modified VG Scientific ESCALAB II, the metrology spectrometer, operated in both the constant ΔE/E and constant ΔE modes, are presented and compared with theoretical estimates. It is shown that an exceptionally detailed electron‐optical calculation, involving proprietary information, would be required to match the accuracy of the experimental procedures developed. Removal of the spectrometer transmission function and the detector sensitivity terms allow the measured spectrum to be converted to the true electron emission spectrum, irrespective of the mode of operation. This provides the first step to the provision of reference samples to calibrate the transmission functions and detector sensitivities of all instruments so that they, in turn, may produce true electron emission spectra. This is vital if: (1) all instruments are to give consistent results; (2) theoretical terms are to be used in quantifying either AES or XPS; (3) reference data banks are to be established for AES or XPS.

Quantitative AES: Calibration of spectrometers for true spectral measurements—results of a VAMAS round robin and recommendations for acquiring reference data banks

AbstractAs a result of careful calibration, a metrology spectrometer has been developed at the National Physical Laboratory (NPL) to give true spectra. This instrument has been used to measure the true spectra from three reference materials under defined conditions in AES. Measurements for these reference materials, on any other instrument, allow that instrument's intensity–energy response function to be calibrated so that that instrument, in turn, may produce true spectra. In a VAMAS interlaboratory assessment involving 38 respondees, these methods and data have been tested. The results show that AES instruments may be calibrated over the energy range 10–2500 eV to give true spectra to an accuracy in the range 1.5–3.0% in the direct mode and ∼12% in the differential mode. For the first time, all these instruments may be calibrated to give: (1) the same spectra; and (2) spectra in which the instrumental systematic intensity errors are reduced to the above levels.

Quantitative AES: Determination of the effects of the relative orientations of the sample, electron gun and spectrometer on the direct spectrum shape for the establishment of standard reference spectra

AbstractThe precise shape of the whole direct spectrum in AES depends on the processes in the sample and on the properties of the measurement system. In this paper we characterize, in detail, the intensities emitted from ion sputter‐cleaned copper and silver foils in the direct spectrum in order to understand better the processes in the sample controlling those intensities. Characterizations of the dependencies of the intensities on the angle of incidence of the electron beam and on the angle of emission of the detected electrons provide rules allowing the transference of reference spectra between different instrumental cinfigurations and conditions. The precise evaluation of the rules is essential if reference data banks are to be transferred for instrument to instrument. Furthermore, by tracing the spectra back to an instrument with known properties we may establish standard reference spectra, which may then be used to calibrate, in other instruments, the combined energy dependencies of the spectrometer transmission function and detector sensitivity with accuracy. This calibration enables all instruments to be used to measure true spectra for the first time.

Reference books and data banks on the thermodynamic properties of individual substances

Abstract