Authors:Bo-chao Xu, W. Burnett, Derek Lane-Smith, and Zhi-gang Yu
Measurements of 222Rn (“radon”) in the environment are important in the geosciences and radiation-protection fields. We demonstrate here a simple
laboratory-based calibration system to evaluate the efficiency of radon detectors with a reproducibility of about ±2%. The
system uses a closed-loop air circulation design with 226Ra adsorbed onto MnO2-impregnated fiber as a radon source. Two RAD7 radon detectors (Durridge Co., Inc.) that were precisely calibrated at Durridge’s
in-house calibration facility are used as secondary standards. By parallel analysis of the radon-enriched air within the closed
loop, the test RAD7s are assigned a calibration coefficient to be applied to future measurements. We also performed a side-by-side
intercomparison with two RAD7s in a high-radon natural environmental setting (limestone cave in Florida) that produced comparable
A useful method for crystal detector calibration by using point sources is presented. The method is applied to determine the total efficiency of a 80×80 mm NaI/Tl/ crystal in an energy window suitable for134Cs+137Cs activity evaluation in a sample of 750 cm3.
The Unified Grain Moisture Algorithm is
capable of improved accuracy and allows the combination of many grain types
into a single “unified calibration”. The purposes of this research were to
establish processes for determining unifying parameters from the chemical and
physical properties of grains. The data used in this research were obtained as
part of the United States Department of Agriculture-Grain Inspection, Packers
and Stockyards Administration's Annual Moisture Calibration Study. More than
5,000 grain samples were tested with a Hewlett-Packard 4291A Material/Impedance
Analyzer. Temperature tests were done with a Very High Frequency prototype
system at Corvinus University of Budapest. Typical chemical and physical
parameters for each of the major grain types were obtained from the literature.
Data were analyzed by multivariate chemometric methods. One of the most
important unifying parameters (Slope) and the temperature correction
coefficient were successfully modeled. The Offset and Translation unifying
parameters were not modeled successfully, but these parameters can be estimated
relatively easily through limited grain tests.
In this paper, it is made a study of the accuracy of an isothermal titration calorimeter in the operating mode of ‘continuous
injection’. The experimental equipment has been a TAM2277-201/2250 by Thermometric AB and the liquid mixtures used in the
calibration have been the mixture cyclohexane+benzene and the mixture water+ethanol. The calibration contemplates different
effects that affect the uncertainty in the determination of the sensitivity, the effect of the liquid injection, the treatment
of the calorimetric signal, the variation of the experimental baseline and the different noises included in the calorimetric
A procedure for calibrating the temperature scale of a DSC is described. A different calibration trend was obtained using
the transition points of organic compounds compared to that found using the melting points of highly pure metals. The crystal-crystal
transitions of three ammonium salts were studied by this method; ammonium dihydrogen phosphate and ammonium sulphate were
found to be suitable reference materials in the region −150 to 0°C, but ammonium nitrate was found to be unsuitable due to
poorly defined transition points and inconsistent thermal behaviour.
This paper first explains the need to define subfields of science by means of “filters” that selectively retrieve papers from
a database, and then describes how such filters are constructed and calibrated. Good filters should have precision and recall
of the order of 90% so as to be representative of a subfield; they are created by an interactive partnership between an expert
in the subject and a bibliometrician. They are based primarily on the use of title keywords, often in combination rather than
singly, and specialist journals. Their calibration depends on experts marking lists of papers extracted by the filter as relevant,
don't know or not relevant. This allows the actual size of a subfield to be estimated and hence the relative importance accorded
to it within a major field of science. It permits organisations and countries to see their contributions to individual scientific
subfields in detail.
Authors:E. Charsley, J. Davies, E. Glöggler, N. Hawkins, G. Höhne, T. Lever, K. Peters, M. Richardson, I. Rothemund, and A. Stegmayer
With some attention to temperature calibration but no other special precautions the temperatures of both solid-solid and melting
transitions can be determined to within a few tenths of a Kelvin of absolute values in a range of heat-flux and power-compensation
DSC instruments. Materials showing several solid-solid transitions are potentially useful multiple calibrants but require
some work to define appropriate thermal treatments that lead to reproducible behaviour.
The evaluation of the accuracy of thin elemental standards produced by Micromatter Co., which are widely used for the calibration
of the detection sensitivity of PIXE analysis systems, is presented in terms of Rutherford scattering measurements of the
thickness of 68 standards covering a range of 59 different elements.
A number of compounds is investigated for DSC calibration during cooling. Adamantane and Zn show fast reversible transitions
and can be applied both for temperature and for heat calibrations. A third compound, namely 4,4’-azoxyanisole, has a liquid
crystal to isotropic liquid transition at 409K. This compound can be used for temperature calibration. Heat calibration with
this compound is more problematic because of the small heat effect and the construction of the baseline. Other compounds like
NaNO3, In, Hg and Pb, show a slight supercooling. Nevertheless they can be used for heat calibration. The use of large samples
of NaNO3 and In gives the possibility to construct the equilibrium onset temperatures of the cooling peaks, so these two compounds
are also appropriate for temperature calibration on cooling.
Authors:György Zoltán Radnóczi, Zoltán Herceg, and Tamás Rafael Kiss
modern microscopes is usually around 1–2%. This accuracy is only achieved if strict imaging requirements are met regarding sample height and defocus. This may be improved by the use of accurate calibration standards like the commonly known Mag