Showing papers by "University of Córdoba (Spain) published in 1988"
TL;DR: The distribution and character of Tertiary magmatism in the nonvolcanic region of shallow subduction between 28°S and 33°S in the Andes correlates with other geological and geophysical evidence suggesting that the subduction zone in this region has shallowed over the last 18 Ma with a major change occurring between 11 and 8 Ma as mentioned in this paper.
118 citations
TL;DR: In this paper, the ion-exchanger located in the flow cell of an unsegmented flow system is applied to the determination of copper(II) based on the formation of a colored chelate with 1-(2-pyridylazo)-2-naphthol retained on Dowex 50W resin.
74 citations
TL;DR: In this paper, the influence of the starting aluminum salt (chloride, nitrate, or sulfate) and the pretreatment temperature (773-1273 K) on textural properties, crystal structure, and surface acidity of AlPO4 (Al P = 1 ) catalysts was studied in order to learn how preparation conditions affect catalyst activity in organocationic reactions.
63 citations
TL;DR: The results presented in this paper suggest that the Ara forward and the His reverse mutation tests are sensitive to the mutagenicity of different constituents in coffee solutions, and it is proposed that the His test, sensitive at high coffee doses, mainly recognizes the mutAGenicity of methylglyoxal, whilst the Ara test,sensitive at low coffee dose, mainly detects themutagenic activity of hydrogen peroxide.
Abstract: The mutagenic activities of 6 of the chemicals identified in coffee solutions were assayed with the Salmonella Ara test, under experimental conditions optimized for coffee mutagenicity. Caffeine was the only non-mutagenic compound. Among the other 5 chemicals, hydrogen peroxide was the strongest mutagen and chlorogenic acid the weakest; methylglyoxal, glyoxal and caffeic acid exhibited intermediate mutagenicities. The minimal mutagenic doses of these components correlated negatively with their relative concentrations in coffee. It was concluded that chlorogenic acid, caffeic acid, glyoxal and methylglyoxal cannot contribute alone to the mutagenicity of coffee in the Ara test, since their minimal mutagenic concentrations were much higher than their respective levels in the coffee samples assayed. By contrast, 40-60% of the mutagenic activity in coffee and also in tea could be attributed to their H2O2 contents. Catalase abolished more than 95% of the mutagenic activity of coffee, as detected by the Ara test. A similar sensitivity to catalase has been reported by other authors in relation to the coffee mutagenicity identified by the Salmonella His test. Nevertheless, the results presented in this paper suggest that the Ara forward and the His reverse mutation tests are sensitive to the mutagenicity of different constituents in coffee solutions. We propose that the His test, sensitive at high coffee doses, mainly recognizes the mutagenicity of methylglyoxal, whilst the Ara test, sensitive at low coffee doses, mainly detects the mutagenic activity of hydrogen peroxide. The data reported also suggest that the direct-acting mutagenicity(ies) detected by the Ara test in tea solutions is (are) based on similar, if not identical, mechanisms.
51 citations
Journal Article•
TL;DR: The use of the immunohistochemical determination of CEA in improving the morphological examination of these differentiation areas and their scant presence in the prognosis of urothelial carcinomas involving squamous and/or glandular focal differentiation are discussed.
Abstract: This paper reports the immunochemical expression of carcinoembryonic antigen in the squamous, glandular and mixed differentiation areas observed in 190 urothelial urinary bladder carcinomas. The antigen was found to occur in 75% and 81% of all papillary and solid infiltrating carcinomas, respectively. The use of the immunohistochemical determination of CEA in improving the morphological examination of these differentiation areas and their scant presence in the prognosis of urothelial carcinomas involving squamous and/or glandular focal differentiation are discussed.
48 citations
TL;DR: A configuration with internally coupled valves and a reductant column located in the loop of the secondary valve is proposed for the simultaneous determination of nitrite and nitrate.
44 citations
TL;DR: A cyclic kinetics of this subcellular component in higher-plant meristems, coupled with early mitotic events is indicated in onion root meristEMS and Golgi apparatus.
Abstract: In onion root meristems, the number of dictyosomes per cell shows a kinetics of growth strongly related to the cell cycle. During the interphase of steady-state proliferative cells, the volume density and numerical density of the Golgi apparatus decrease to reach minimum values in late-interphase cells, characterized by their greatest length. This pattern is also found in the total volume occupied by Golgi apparatus. Once in mitosis, the above-mentioned parameters begin to increase reaching maximum mean values in telophase. After the experimental uncoupling of chromosome and growth cycles by presynchronization with hydroxyurea, we found a similar behaviour pattern in the Golgi apparatus: decreasing values during interphase and a triggering of Golgi-apparatus growth in prophase independently of the bigger cell sizes reached in mitosis as an effect of pretreatment with hydroxyurea. These results indicate a cyclic kinetics of this subcellular component in higher-plant meristems, coupled with early mitotic events.
44 citations
TL;DR: In this article, the classification of oxalate in urine is reviewed and classified into seven groups: direct precipitation, solvent liquid-liquid extraction, isotope dilution, chromatographic (gas and HPLC), enzymatic (involving enzymes dissolved or immobilized on reactors or electrodes), flow methods (segmented and non-segmenting), and other methods.
43 citations
TL;DR: Six sunflower lines were grown in nutrient solution to characterize their sensitivity to bicarbonate‐induced Fe chlorosis and chlorosis score was inversely correlated to chlorophyll and Fe concentrations in the uppermost leaves.
Abstract: Six sunflower (Helianthus annuus L.) lines were grown in nutrient solution to characterize their sensitivity to bicarbonate‐induced Fe chlorosis. Sensitivity was evaluated by chlorosis score and growth reduction relative to the control without added bicarbonate. Chlorosis score was inversely correlated to chlorophyll and Fe concentrations in the uppermost leaves. This technique seems valuable for determining genotypic differences in sensitivity to Fe‐induced chlorosis in sunflower. Bicarbonate treatment resulted in an increase in the Ca, Mg, K and Mn and in a decrease in the Fe and P concentrations in leaves. In roots, bicarbonate treatment resulted in a decrease in the Fe and Mn concentrations. Some of the effects of bicarbonate on these elemental compositions were related to the degree of chlorosis.
38 citations
37 citations
TL;DR: Yeast glucose-6-phosphate dehydrogenase was inhibited by low NADPH concentrations in cell-free extracts, and de-inhibited by G SSG; extensive dialysis of the crude extract did not diminish the GSSG effect.
Abstract: Yeast glucose-6-phosphate dehydrogenase was inhibited by low NADPH concentrations in cell-free extracts, and de-inhibited by GSSG; extensive dialysis of the crude extract did not diminish the GSSG effect. Immunoprecipitation of glutathione reductase abolished the de-inhibition of glucose-6-phosphate dehydrogenase by GSSG. Purified glucose-6-phosphate dehydrogenase was inhibited by NADPH but not de-inhibited by GSSG, and upon addition of pure glutathione reductase GSSG completely de-inhibited the glucose-6-phosphate dehydrogenase.
TL;DR: Examination of barbels from a first-order stream located in the Guadalquivir River basin revealed that this stock had the lowest growth rate of 37 different European barbel populations.
Abstract: This study was based on examination of 1476 barbels from a first-order stream located in the Guadalquivir River basin (38°N, 4°43′W). This stock comprised nine age groups of male and 11 of females. No growth was recorded between October and March, most occurring in April–June and, to a lesser extent, in July–September. A classification analysis revealed that this stock had the lowest growth rate of 37 different European barbel populations. Length–weight relationships were obtained for 12 barbel categories and used to estimate both condition and instantaneous growth rate. Relative condition (before and after subtracting gonad weight) was similar in both sexes and was affected by gonad growth and environmental summer conditions.
Spawning occurred during the second half of May (15 May is suggested as the birthday). Gonads began to develop in September (females) and in February (males). Males matured at between 7 and 9 cm fork length (f.l.) (2–4 years old) and females between 11 and 16 cm (6–7 years). The fecundity of this stock was represented by the formula F=6.07 10 4 f.l. (mm)3.0667. Larger and older fish showed a higher fecundity and bigger eggs. The overall sex ratio did not differ from 1:1.
TL;DR: From genetic and kinetic evidences it is concluded that in C. reinhardtii two different carriers are responsible for the transport of both ammonium and methamphetamine and that methylammonium (ammonium) transport is a reversible process probably inhibited by the intracellular ammonium which, in turn, regulates nitrate and nitrite reductase levels.
TL;DR: In this article, a goal programming model was used to analyse optimum fertilizer combinations, instead of being fixed values as in traditional linear programming, are considered targets which may or may not be achieved.
Abstract: A goal programming model was used to analyse optimum fertilizer combinations. Under this approach, the fertilizer requirements, instead of being fixed values as in traditional linear programming, are considered targets which may or may not be achieved. A penalty system coupled to the goal programming model makes the specified lower and upper levels of nutrients more flexible and realistic. A simple example is used to expound the model, and then applied to real data to give optimum combinations of fertilizers for sugar beet in Western Andalusia (Spain).
TL;DR: In this paper, a low-temperature hydrothermal treatment of the 03 crystalline modification of LiCoO2 at 200°C in acid solutions yields HCoO 2.
TL;DR: A simple hydrological model contributes to the understanding of these water harvesting devices as discussed by the authors, which can distinguish three main types depending on the location in the basin: the ca n ada catch the runoff from small, narrow valleys in the upstream part of the watershed; the boquera, an earth dyke, diverts the flood waters occasionally appearing in upland dry washes, to small cultivated areas previously prepared in the bed border; the third one occurs near the basin outlet, where a more elaborated stone-made diversion dyke leads the waters to a conveyance canal
TL;DR: It appears that the integrity of glucan moieities of the cell surface glycoconjugates are necessary for the optimal function of ascorbate free radical reduction by NADH, which could be considered as part of the transplasma membrane electron transport system.
TL;DR: In this paper, the reduction of acetophenone using 3% palladium catalysts supported on a Spanish sepiolite and on different SiO 2 AlPO 4 (80:20 w/w) systems were compared.
TL;DR: In this paper, the liquid phase catalytic hydrogenation of several α,β-unsaturated alcohols has been carried out at 293-323 K and in an initial hydrogen pressure range of 0.3-0.7 MPa, on a 1 wt% rhodium catalyst supported on aluminum orthophosphate.
TL;DR: In this article, the authors studied the variation of the rate and equilibrium constants of the reaction between pyridoxal 5'-phosphate (PLP) and n-hexylamine as a function of the pH at a temperature of 25 °C and an ionic strength of 0.1, in media of different polarity.
Journal Article•
TL;DR: The data reported in this paper suggest that the Ara forward mutation test is less prone than the His reverse mutation test or the SOS chromotest to misclassify as negative carcinogenic compounds, and should be considered as an alternative to other bacterial assays in general, massive, and primary screening for genotoxic carcinogens.
Abstract: The l-arabinose resistance test with Salmonella typhimurium (Ara test) is a forward mutation assay which selects a single phenotypic change (from l-arabinose sensitivity to l-arabinose resistance) in a unique tester strain (an araD mutant). The present study examined the ability of the Ara test to identify as mutagens different classes of chemical carcinogens, including six with detection problems in most bacterial assays. A noncarcinogen related in chemical structure to the selected carcinogen was included whenever possible. A total of 25 organic compounds was assayed by means of a standard mutagenesis procedure: the plate-incorporation test in the presence (if required) of 10% S9 from rat liver induced with Aroclor 1254. Chemicals giving negative or inconclusive results were then retested using other common in vitro mutagenesis conditions. The Ara test detected as mutagens all but one (Urethane) of the 15 established carcinogens and six out of the nine chemicals with questionable or nonassayed carcinogenicity. The compound mutagenic at the lowest dose was ethionine (0.57 nmol), one of the carcinogens undetected by the popular histidine reverse mutation assay (Ames test) or by the SOS chromotest. Actually, only benzo( a )pyrene was found mutagenic at a dose (0.77 nmol) close to that of ethionine. The data reported in this paper suggest that the Ara forward mutation test is less prone than the His reverse mutation test or the SOS chromotest to misclassify as negative carcinogenic compounds. Consequently, it should be considered as an alternative to other bacterial assays in general, massive, and primary screening for genotoxic carcinogens.
TL;DR: In this paper, a cyclic voltammetric unit for potential scans is connected to a three-electrode cell (carbon-paste working electrode, silver/silver chloride reference electrode and glassy-carbon auxiliary electrode).
TL;DR: In this paper, the formation of a new lithium ferrite modification structurally similar to γ-Fe 2 O 3 and LiFe 5 O 8 by direct precipitation from Fe(III) solutions is described.
TL;DR: In this article, several diagnostic criteria have been developed to differentiate electrochemical processes coupled or not to first-order reactions, and they have been applied to the reductions of Cd(II) ion, diacetyl and alloxan.
TL;DR: The method is highly selective and free from interference by other pesticides tested and has been applied to the analysis of environmental samples for carbaryl and 1-naphthol.
TL;DR: In this article, a curve-fitting program running on a APPLE II+ is proposed and tested for electrochemical kinetics and routine analyses are also considered, and the results show that the program can be used to analyze first-and second-order processes.
TL;DR: Females that mated with inoculated males that had been inoculated with S. littoralis nuclear polyhedrosis virus produced normal numbers of eggs, but showed a significant reduction in egg hatchability when compared with females that mates with untreated males.
Journal Article•
TL;DR: This work has studied the annual variation of the concentration of Cladosporium spores in three different types of rooms in 14 homes in the city of Córdoba, Spain, and found only small differences between the flora identified in the different rooms.
Abstract: We have studied the annual variation of the concentration of Cladosporium spores in three different types of rooms in 14 homes in the city of Cordoba, Spain. Ten species have been isolated, some of which are potentially allergenic. The results also show certain correlations between the concentration of spores and climatic factors, and only small differences between the flora identified in the different rooms.
TL;DR: In this article, the overall concentration of a cationic surfactant can be determined indirectly by measuring the cobalt in the organic layer by a.a.s. The optimum conditions for determining dodecyltrimethylammonium and tetraheptylamium bromide (0.4-9.0 μg ml −1 ) are described.
TL;DR: Phenylalanine ammonia-lyase activity was strongly inactivated by some heavy metal ions and by the amino group reagent acetic anhydride, but was latter effect was completely prevented by the simultaneous presence of substrate.