ALBERT

Notes: A study has been made of the effect of properties and composition of soils on the adsorption of ethofumesate. Adsorption isotherms of ethofumesate by agricultural and natural soils and by montmorillonite and humic acid were obtained. The correlations between the Freundlich K constants, and Kd distribution coefficients and the soil parameters were determined. Significant correlations (P〈0.05) were found between K and clay content and between Kd and smectite content for the agricultural soils but the correlation with organic matter content was of borderline or no significance.Considering the agricultural and natural soils together or the soils with an organic matter content 〉2%, a highly significant correlation was found between K and the organic matter content. According to the r2 determination coefficient, the organic matter content accounts for 88.4% of the variability in adsorption in the first case, and 92.2% in the second case. The log10 Kdom values of soils with an organic matter content 〉2% were similar and confirm the importance of the organic matter as a determinant parameter in the adsorption of ethofumesate by these soils. The adsorption of the herbicide by montmorillonite and humic acid confirmed the results obtained with the soils and point to the importance of the exchangeable cation nature of the samples and of the temperature in the adsorption process. Adsorption de l'éthofumesate dans des sols agri-coles et naturels L'effet des propriétés et de la composition du sol sur l'adsorption de l'ethofumesate a étéétudié. Les isothermes d'adsorption de 1'éthofumesate par des sols agricoles et naturels ainsi que par la montmorillonite et des acides humiques ont été déterminés. Les corrélations entre les caractéris-tiques du sol, les constantes de Freundlich K d'une part et les coefficients de distribution Kd d'autre part ont été déterminées. Des corrélations significatives (P〈0.05) ont été mises en évidence entre K et la teneur en argile ainsi qu'entre Kd et la teneur en smectite pour les sols agricoles mais la correlation avec la teneur en matisre organique etait tout juste ou non significative.Lorsqu'on considérait les sols agricoles et naturels ensemble ou les sols dont la teneur en matière organique est supérieure à 2%, une corrélation hautement significative existait entre K et la teneur en matière organique. Le coefficient de détermination r2 montre que la teneur en matière organique explique 88.4% de la vari-abilité de l'adsorption dans le premier cas et 92.2% dans le second cas. Le log10 Kdométait similaire pour les sols de teneur en matière organique 〉2%, ce qui confirme l'importance du paramètre matière organique dans l'adsorption de 1'ethofumesate par ces sols. L'adsorption de I'herbicide par la montmorillonite et les acides humiques a confirmé les résultats obtenus avec les sols et a montre 1'importance de la température du process et de la nature des cations d'échange des échantillons. Adsorption von Ethofumesat in Acker- and natürlichen Böden Bei der Untersuchung der Wirkung der Eigen-schaften und der Zusammensetzung von Böden auf die Adsorption von Ethofumesat wurden Adsorplions-Isothermen mit Acker- und natürlichen Böden sowie mit Montmorillonit und Huminsäure ermittelt. Die Korrelationen zwischen den Freundlich-Konstanten K sowie den Verteilungskoeffizienten Kd und den Bodenparametern wurden bestimmt. Signifikante Korrelationen (P〈0.05) wurden für K und den Tongehall und für Kd und den Smectit-Gehalt in Ackerböden gefunden, doch die Korrelation mit dem Gehalt an organischer Substanz war marginal oder nicht signifikant. Für Acker-und natürliche Böden insgesamt oder Böden mit einem Gehalt an organischer Substanz von 〉2% wurde eine hochsignifikante Korrelation zwischen K und dem Corg.-Gehalt gefunden. Das Bestimmtheitsmaß (r2) für die organische Substanz lag swischen 88.4% im ersten und 92.2% im zweiten Fall. Die log10Koc-Werte Böden mit einem Corg.-Gehalt von 〉2 % waren ähnlich und bestätigen die Bedeutung der organischen Substanz als bestimmenden Parameter für die Adsorption von Ethofumesat in diesen Böden. Die Adsorption des Herbizids an Montmorillonit und Huminsäure unterstreichen die an den Böden gewonnenen Ergebnisse und die Bedeutung der Kationen-Austauschfähigkeit der Proben.

Notes: Sodium dodecyl sulfate (SDS) and 2-mercaptoethanol (2-ME) activated proteolytic enzymes present in extracts of Entamoeba histolytica and E. invadens; SDS (0.5%) and 2-ME (1.4 and 715 mM) doubled the enzymatic activity when assayed on a stained insoluble substrate. Urea (4 M) did not reduce this activity, suggesting that amebic proteases are stable in the above denaturant conditions. Specific reagents for sulfhydryl (-SH) groups completely inhibited proteolytic activity regardless of pH. Inhibition with alkylating agents, such as N-ethylmaleimide and iodoacetamide, was reversed with 715 mM 2-ME as was also observed with papain. We conclude from these results that the main proteolytic enzymes contained in extracts of E. histolytica and E. invadens are dependent on free thiol groups.

Notes: . Restriction endonuclease mapping of the Trypanosoma cruzi kinetoplast DNA maxicircle was performed in nine cloned stocks using maxicircle probes from T. brucei. Analysis of the maxicircle 13–15-kbp encoding region allowed cloned stocks to be divided into three groups: A, B, and C. Parasites from groups A and B had 3% sequence divergence while parasites from group C showed 16–17% sequence divergence with regard to parasites from groups A and B. Cross-hybridization experiments demonstrated that the 23–25-kbp maxicircle divergent region was similar in sequence in group A and B, but different in group C parasites. The high homology of the T. cruzi and T. brucei encoding regions allowed the use of T. brucei probes to detect T. cruzi transcripts, whose overall picture did not differ for parasites from any of the nine assayed clones.

Notes: The author has investigated the role played by project selection methods in defining a firm's technology strategy, as exemplified by a sample of innovative companies in Spain. The information was collected by a combination of questionnaire and interview with key personnel.The author was able to classify strategies into four groups: (1) a planning strategy, essentially a negotiation comprising top-down and bottom-up elements; (2) an economic strategy in which a large number of economic criteria set in advance by top management are used to evaluate projects; (3) a market strategy in which R&D is seen more or less as an adjunct to the Marketing function, which defines the products needed and negotiates the programme with top management; (4) a technical strategy, used in circumstances in which technological innovation is essential and in which, therefore, economic factors take a subsidiary place.The author's data show that in companies operating a planning strategy project selection methods of various, perhaps ad hoc kinds play a key role in reaching a company consensus. For those using an economic strategy the selection criteria are predetermined and selection methods inflexible. In the case of the market strategy, evaluation methods are used solely to help to rank projects prior to selection. Firms employing the technical strategy clearly base their decisions purely on the technical merit of the various projects put up for implementation.The paper includes information on the types of selection method used, broken down by company size and other similar criteria, and comparisons with practice in the USA, France and some other countries.

Notes: DNA oligotyping was used to determine HLA-A28 subtypes in 25 unrelated Caucasian individuals living in or around Seville, Spain. Results showed that HLA-A*6802 was the most frequent allele, found in 14 individuals (53.8%), followed by HLA-68.3, which was present in eight subjects (30.8%), and both combined represented 84.6% of A28+ individuals in the area. The HLA-A*6801 allele was found in three individuals (11.5%), whereas HLA-A*6901 was present in one subject only (3.8%). Results indicate that the distribution of HLA-A28 alleles can vary among different Caucasoid populations. In this way, the high frequency obtained for A*6802 supports previous studies suggesting that the HLA-A*6802 allele was prevalent in people of the Mediterranean basin, in contrast to A*6801, prevalent in northern European populations.