A kinetic study of the thermal decomposition of the complexes bis-(DL-valinato)copper(II) and bis-(DL-methioninato)copper(II) was carried out using thermogravimetry in a dynamic regime, following the theoretical model of Satava and including the equation used by Johnson and Gallagher:1/1−α−1=kt. Kinetic parameters were calculated and are compared with those obtained previously for the complex bis-(L-tryptophanato)copper(II). The sequence of thermal stability found is: Cu(DL-Val)2<Cu(L-Trp)2<Cu(DL-Met)2.
Authors:A. Ramiz, G. Goethals, P. Martin, P. Villa, and P. Godé
Galactose, glucose, xylose and corresponding itol derivatives with the general formula Su—ZR in which Z is an amido group either NHCO (type I) or NR'CO (type II) were synthetized and their mesophasic behaviour studied. It was shown that the thermotropic and lyotropic phase transition temperatures are influenced by the following structural parameters: alkyl or perfluoroalkyl chain length, Z junction, free OH group number, cyclic or acyclic Su structure.
Authors:P. Martin, P. Godé, P. Villa, and G. Goethals
We studied the phase transition temperatures of a series of amphiphilic D-xylopyranose and D-xylofuranose derivatives in which the lipophilic part is an alkyl chain R (n-CnH2n+1), regiospecifically linked to D-xylose, at different positions, by Z which is an atom or a functional group (O, S, O–(CH2)3–S). The alkyl chain was moved from the C-1 to the C-5 position in the xylose moiety, thereby allowing us to compare directly
the phase transition temperatures of the individual materials. These compounds give thermotropic and/or lyotropic liquid crystals.
In some cases, we also observed solid–solid phase transitions.
Authors:T. Martins, J. Matos, G. Vicentini, and P. Isolani
Rare earth picrate complexes
with L-leucine (Leu) were synthesized and
characterized. Elemental analysis (CHN), EDTA titrations and thermogravimetric
data suggest a general formula RE(pic)32Leu⋅5H2O
(RE=La–Lu, Y and pic=picrate).
IR spectra indicate the presence of water and suggest that L-leucine is coordinated
to the central ion through the nitrogen of the aminogroup. The absorption
spectrum of the solid Nd compound indicates that the metal-ligand bonds show
a weak covalent character. Emission spectra and biexponential behavior of
the luminescence decay of the Eu compound suggest the existence of polymeric
species. Thermal analysis results indicate that all the compounds present
a similar behavior, with five major thermal decomposition steps. The final
products are rare earth oxides. A slow heating rate is necessary to observe
all decomposition steps.
Authors:P. Martins-Lopes, B. Maças, and H. Guedes-Pinto
Genetic improvement in aluminium tolerance is one of the most cost-effective solutions to improve the productivity of wheat (
L.) in acid soils. Sources of tolerance to this abiotic stress within adapted germplasm are limited, so the identification and characterisation of new sources are of some priority for the future of plant breeding in target areas. The aim of this study was to evaluate the response to aluminium stress of an old Portuguese wheat collection and to select the most tolerant ones for genetic and breeding purposes. An old collection of Portuguese wheat cultivars and some ‘Barbela’ lines were tested and classified in relation to aluminium tolerance and compared to modern wheat cultivars using a hydroponic approach. Three bread wheat cultivars (‘Viloso Mole’, Magueija’ and ‘Ruivo’) showed greater tolerance to 5 ppm aluminium than the international wheat standard cultivar ‘BH1146’, and so represent excellent material for understanding the genetic control of aluminium tolerance. In addition, several accessions of the Portuguese landrace ‘Barbela’ were outstanding in terms of aluminium tolerance. In particular, line 7/72/92 had a pronounced advantage over ‘BH1146’ in terms of root regrowth.
Authors:A. Murray, R. Marten, A. Johnston, and P. Martin
The analytical potential of low level, high resolution gamma-ray spectrometry for naturally occurring radionuclides at environmental levels is described, with particular emphasis on detector background levels and sensitivity. Comparisons are drawn between the performance of a specially designed low background detector system, and that of standard off the shelf devices. Sample characteristics, calibration procedures and checks, are described, and empirical minimum detection limits of between 0.4 Bq·kg–1 (226Ra,228Th) and 10 Bq·kg–1 (210Pb) are derived for soil or sediment samples of about 250 g. Representative analyses of a variety of environmental samples, including water, plant material, animal tissue and sediment, are given to illustrate the routine use of the spectrometer.
Authors:T. L. White, T. L. White, K. B. Martin, K. B. Martin, L. N. Oji, L. N. Oji, D. P. DiPrete, D. P. DiPrete, and W. R. Wilmarth
One waste remediation process used at the Savannah River Site was the in-tank precipitation of the beta-emitting 137Cs from high-level waste (HLW) using sodium tetraphenylborate (NaTPB) followed by processing the resulting decontaminated
filtrate into grout at the Saltstone Production Facility (SPF). A simple method was developed for the monitoring of tetraphenylborate
(TPB) in high-level waste (HLW) containing up to 0.38 Ci/gal of 137Cs. Separation was achieved by extraction of the high sodium-bearing waste with acetonitrile followed by analysis using reversed-phase
high performance liquid chromatography (HPLC). The sample preparation method allowed for the handling of an organic extraction
layer that had 94% less acitivity than the HLW sample. The subsequent HPLC analysis of the extraction layer determined the
TPB concentration in HLW waste to 0.8 mg/l with a %rsd of 8.
Authors:P. Martín-Palomino, S. Píriz, Ruth Jiménez, F. J. Serrano, and S. Vadillo
This research consists of an evaluation of the effectiveness of different substances administered as adjuvants in the stimulation of humoral immune response induced by the vaccine composed of strains A1, A2 and C of Dichelobacter nodosus. To do this, a total of 120 Merino sheep were vaccinated and revaccinated. These sheep were selected from a farm located in the region of Extremadura (Spain), and they were divided into 12 groups of 10 animals each. An additional group with 10 sheep was used as control. The immune response (titre of antibodies) was determined by agglutination tests and ELISA. The most pronounced immune response was obtained by the use of Freund's incomplete adjuvant and aluminium hydroxide as adjuvants.