Stoichiometric, stable fluorides for comparison standards in neutron activation analysis were prepared by horizontal zone-refining
or sublimation in HF atmospheres. The fluorides of Na, Mg and Al were shown by thermogravimetry to be anhydrous and to remain
water-free after exposure to room air. Fluorine in the purified samples was separated by the pyrohydrolysis method and subsequently
measured by acid-base titrimetry or selective ion electrodes. Deviations from theoretical values were ±0.1, ±0.9 and ±2.8%
respectively for fluorides of Na, Mg and Al.
Authors:Xue-Wei Han, Cai-Rong Zhou, and Xiao-Hua Shi
pure substance were determined by a precision oxygen bomb calorimeter. Then the standard molar enthalpies of combustion and formation were calculated by thermodynamics principle. So the related studies can provide a thermodynamic basis for taurine
Bibliometric standards are essential for comparative research. However, these standards can not be set by committee but must evolve through an on-going debate. Perhaps, the Scientometric community needs a refereed forum more dedicated to methodological issues than policy matters in which the standards debate can proceed in a focused and professional manner.
specific surface area, density, and chemical activity. In our previous papers [ 8 ], some metal phosphates, e.g., NH 4 MPO 4 ·H 2 O (M = Mn 2+ , Co 2+ , Ni 2+ , Fe 2+ , Zn 2+ , Cu 2+ ), have been prepared by solid-state reaction. Their standard molar
). As a matter of fact, in Modern Standard Arabic (henceforth MSA), 2 there are only two verbal patterns in which a radical is placed adjacent to a pattern consonant. 3 The first pattern is “ɪn-a-a-”, in which the coronal nasal /n/ occurs immediately
The paper shows how, from the neutron irradiation of multi-element standards, one can derive neutron flux parameters for the irradiation position and, at the same time, greatly improve knowledge of nuclear data parameters, such as thermal cross sections, resonance integrals and gamma raz emission probabilities, for the nuclides concerned. It is then shown how the resulting neutron flux parameters and nuclear data parameters can be used to carry out neutron activation analysis without further irradiation of multi-element standards. The technique is applied to the analysis of Chinese geochemical reference material
Bibliometric studies are mostly empirical nature and they are mostly centred arround presentation of facts and data. There are very few studies which are centred arround theoretical foundation. The facts are gathered either through surveys or from published bibliographies, indexes, data bases. Based on these facts, empirical models and principles are being developed. The normative principles and standards have to evolve from the logical analyses of the empirical models. The stage is set to integrate empirical models of bibliometrics into standards. Future, bibliometrics studies have to address this issue and reach the stage of normative principles.
A theory of “subalgebra basis” analogous to standard basis (the generalization of Gröbner bases to monomial orderings which are not necessarily well orderings ) for ideals in polynomial rings over a field is developed. We call these bases “SASBI Basis” for “Subalgebra Analogue to Standard Basis for Ideals”. The case of global orderings, here they are called “SAGBI Basis” for “Subalgebra Analogue to Gröbner Basis for Ideals”, is treated in . Sasbi bases may be infinite. In this paper we consider subalgebras admitting a finite Sasbi basis and give algorithms to compute them.
INAA results of 11 standard reference materials used in archaeometric investigations of pottery as well as in environmental analysis are presented. The values obtained for 24 elements are compared with the certificate values as well as with the analytical data of other investigators. The accuracy of analysis is discussed.
A laboratory standard for the determination of long-lived radionuclides in nuclear waste has been prepared using concrete as matrix. It will be used to check sample preparation procedures, chemical separations and methods for the determination of nuclides, e.g., nuclear counting techniques or mass spectrometry. The material chosen was a fine-grained ready-to-use cement mixture, to which the following radionuclides were added:60Co and137Cs as -ray-emitting nuclides,99Tc,90Sr and55Fe as radionuclides emitting pure -radiation or low-energy electrons, and233U,237Np,238Pu and241Am as -emitters. Care was taken to attain a homogeneous distribution of the nuclides in the standard material. Pieces of about 1 g were formed as suitable and representative samples. Repeated analyses were carried out with the standard to check its homogeneity. The analytical procedures are described in brief. The pieces of the standard material have the same content of nuclides within ±5% at a 95% level of confidence.