Origin and development of the International Confederation for Thermal Analysis (ICTA)

The history of ICTA, from its conception at the First International Conference on Thermal Analysis in Aberdeen, Scotland, in 1965 through the subsequent eight Conferences to the 10th ICTA Congress in Hatfield, England, in 1992, is outlined. Brief biographies of Past-Presidents are appended.     

KINETIC BEHAVIOR OF EPR SIGNAL I: INDUCTION EFFECTS IN INTACT ALGAE

Abstract— There is considerable evidence that the light-induced narrow EPR signal I at g = 2·0025 in green algae is a reflection of the turnover of the photosynthetic reaction center, P700. A lag period or induction effect of the formation of this signal, subsequent to a dark period in whole fresh cells, is similar to induction effects for the bleaching of P700. The rate of formation of the signal is slower the longer the preceding dark period. DCMU does not much affect the induction phenomenon, but heating the cells to 60° abolishes it. Some substance or process which exists in the intact cell is altered by light and is detectable by its effect on signal I and on the rate of light-induced oxidation of P700 and cytochrome.     

A potentiometric study of the water-soluble silver(I) complexes of n,n'-bis(2-hydroxyethyl)dithiooxamide : Part III. Determination of the different species

Silver(I) and N,N'-bis(2-hydroxyethyl)dithiooxamide (H₂X) in acidic solutions, form a series of water-soluble polynuclear complexes. These complexes can be represented by two general formulae: H_2qAg_pX_q and H_2q-1Ag_pX_q with q=1,2,3 and p=q, q-1.     

Analytical aspects of some organic acids

Summary A direct titrimetric method for the estimation of iron(III) has been developed, which involves the adjustment of concentration of iron(III) andPh, dilution, addition of 1 ml of 2% indicator solution and titration with EDTA (30° to 35° C). It is based on the fact that the iron(III) forms a blue coloured complex which is destroyed at the 11 molar ratio making the end-point of the titration. Quantity of iron(III) as small as 23.2 mg can be titrated accurately when present in a volume of 100 ml. Study of interferences revealed that quite a number of elements like Be²⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, UO₂ ²⁺ and Mn²⁺ does not interfere, whereas much interference is caused by Cu²⁺, Zn²⁺, Pb²⁺, Fe²⁺, Co²⁺, Ni²⁺, ZrO²⁺, V0²⁺, Al³⁺, Cr³⁺, Ti⁴⁺, Ce⁴⁺ and Th⁴⁺. The method proposed for iron(III) is selective and should be of considerable use in many cases.Part III: See Z. analyt. Chem. 167, 332 (1959).     

Geometric structure and electronic properties of neutral and anionic Fe2C3 and Fe2C4 clusters, as obtained by density-functional calculations

We calculated the geometrical structures and electronic properties of neutral and anionic Fe2Cn clusters (n = 3,4) using a density-functional method that employs linear combinations of atomic orbitals as basis sets, standard nonlocal norm-conserving pseudopotentials, and the generalized gradient approximation to exchange and correlation. We show that the ground-state structures of Fe2C3 and Fe2C4 are essentially the same in the neutral and anionic states, namely, planar rings that feature nonadjacent Fe atoms. For the anionic clusters, these findings contrast with previously published results.     

Trace elements in a profile of the unsaturated zone of the São Paulo Basin

This study comprises Tertiary sediments (clays, silts, and fine clayey sands) from the unsaturated zone of the Experimental Station in the University of São Paulo, taken from a nine meters depth profile; ten samples were separated in bulk and <53 m fractions. Chemical composition was determined by INAA to ascertain the distribution of trace elements throughout the sediment deposition, and to establish the background parameters, useful for mobilization studies of such elements after industrial waste disposal.     

Radionuclide X-ray fluorescence analysis of drinking water using preconcentration of trace metals on chelating cellulose exchanger OSTSORB-OXIN

Determination of Cr, Fe, Cu, Zn and Pb in drinking water preconcentrated on a chelating ion exchanger of Czechoslovak production is described. The analytical system consisted of a radionuclide source²³⁸Pu, a Si/Li semiconductor detector and a multichannel analyzer. Results are compared with trehshold limit values recommended for drinking water.     

A switchable radioactive neutron source: Proof-of-principle

The formation of¹⁶⁰Er,¹⁵⁹Dy and¹⁴⁹Gd employing natural dysprosium as target and its irradiation with α-particles was the objective of this work. This is included in a study performed by our group on excitation functions of induced reactions for charged particles on rare earths. A target with metallic foils of Dy was irradiated in the Isochronous Cyclotron at Karlsruhe (Germany) with incident energy up to 88.5 MeV. Due to the contributions of the precursors in the isobaric chains, we were not able to measure the absolute cross sections. Then, the determination of the cumulative cross sections were carried out. Thick target yields for the production of¹⁶⁰Er,¹⁵⁹Dy and¹⁴⁹Gd are also presented. At present we do not know other publications about the functions studied in this work.     

Monitoring the atmospheric stability by using radon concentration measurements: A study in a Central Italy site

Summary Meteorological and radon concentration data referring to a measurement campaign carried out in Urbino, Central Italy, are reported and discussed. This study presents a method allowing monitoring of the vertical atmospheric stability using continuous measurements of radon gas near ground. In particular radon evidences the presence of temperature inversion such as the formation of the nocturnal stable layer and gives information on the vertical turbulence and the motion of air masses. This technique is very useful in describing the temporal evolution of the pollutants in the atmosphere.     

Determination of nitric acid concentration by using europium ion fluorescence

A method is presented for the determination of 2-10M nitric acid based on the fact that the presence of high nitric acid concentration causes an enhancement of the intensity of some bands in the fluorescence spectra of rare earth ions in solution. The 616-nm band of Eu(3+) shows the most dramatic intensity enhancement with increasing nitric acid concentration. The present method, based on the measurement of the ratio of Eu(3+) fluorescent band intensities is shown to be independent of Eu(3+) concentration and relatively free of interference. This robust method allows the presence of an interferent to be determined from the experimental data.