Life cycle assessment of carbon capture and utilization from ammonia process in Mexico.

Post-combustion CO2 capture (PCC) of flue gas from an ammonia plant (AP) and the environmental performance of the carbon capture utilization (CCU) technology for greenhouse gas (GHG) emissions to an enhanced oil recovery (EOR) system in Mexico was performed as case study. The process simulations (PS) and life cycle assessment (LCA) were used as supporting tools to quantify the CO2 capture and their environmental impacts, respectively. Two scenarios were considered: 1) the AP with its shift and CO2 removal unit and 2) Scenario 1 plus PCC of the flue gas from the AP primary reformer (AP-2CO2) and the global warming (GW) impact. Also, the GW of the whole of a CO2-EOR project, from these two streams of captured CO2, was evaluated. Results show that 372,426 tCO2/year can be PCC from the flue gas of the primary reformer and 480,000 tons/y of capacity from the AP. The energy requirement for solvent regeneration is estimated to be 2.8 MJ/kgCO2 or a GW impact of 0.22 kgCO2e/kgCO2 captured. GW performances are 297.6 kgCO2e emitted/barrel (bbl) for scenario one, and 106.5 kgCO2e emitted/bbl for the second. The net emissions, in scenario one, were 0.52 tCO2e/bbl and 0.33 tCO2e/bbl in scenario two. Based on PS, this study could be used to evaluate the potential of CO2 capture of 4080 t/d of 4 ammonia plants. The integration of PS-LCA to a PCC study allows the applicability as methodological framework for the development of a cluster of projects in which of CO2 could be recycled back to fuel, chemical, petrochemical products or for enhanced oil recovery (EOR). With AP-2CO2, "CO2 emission free" ammonia production could be achieved.

Purification and some properties of hemagglutinating protein mutina from bushmaster Lachesis muta snake venom.

Lachesis muta snake venom induced aggregation of bromelain sensitized human erythrocytes at a concentration of 1 mg/ml. The hemagglutinating protein was purified by DEAE-Sephadex A-50 column chromatography. Polyacrylamide gel electrophoresis revealed at least three bands, whereas SDS electrophoresis in the presence of 2-mercaptoethanol showed a single one. Isoelectric focusing revealed hemagglutinating activity in the range of pH 3-8. The maximum peak (mutina) at pH 5.5. This fraction was active in agglutinating human RBC of types A, B, O Rh (+) and B, O Rh (-). One mM EDTA and 1 mM Ca++ did not alter the agglutinating time significantly. Lactose and inositol inhibited the agglutination of A, B, O Rh (+) and B, O Rh (-) human RBC. The present study showed the non specificity of the hemagglutinating activity of mutina. It was also shown that mutina is a non-mitogenic protein.

Comparative investigations of Latin American trypanosomes with lectins and complement lysis test.

Four-days old epimastigote culture forms of different stocks of Trypanosoma cruzi from Colombia, Costa Rica and Mexico as well of Colombian stocks of T. rangeli were tested with 27 lectins and the complement lysis test. While the stocks of T. cruzi and T. rangeli showed common agglutination reactions with the lectins of Canavalia ensiformis and Pisum sativum, only the stocks of T. cruzi were additionally agglutinated by Ricinus communis-120, Glycine maxima, Helix pomatia, Axinella polypoides, Bandeiraea simplicifolia, Bauhinia purpurea, Wistaria floribunda, Abrus precatorius, Aaptos papillata II, Limax flavus and Arachis hypogaea. On the basis of lectin typing, the strains of T. cruzi belong to the PNA-type. While the epimastigote culture forms of T. cruzi stocks were lysed by normal fresh human, rat, chicken, rabbit and guinea pig serum, the culture forms of T. rangeli were only lysed by chicken serum. Mouse serum had no lytic effect on either trypanosome species. Incubation of T. cruzi with neuraminidase did not alter the lytic effect of the sera. The membrane-associated N-acetylneuraminic acid on T. cruzi does not protect the cell surface against the activation of the alternative complement pathway. After treatment of T. cruzi with neuraminidase and subsequent incubation in culture medium, the PNA-type was restored. The cells reacted again with the lectins of Arachis hypogaea, Limax flavus, Aaptos papillata II but not with Triticum vulgaris.

Study of a time lag in the assay of Escherichia coli membrane-bound dehydrogenases based on tetrazolium salt reduction.

The Escherichia coli membrane-bound D-lactate dehydrogenase and succinate dehydrogenase were assayed on the basis of the phenazine methosulfate- (PMS-) mediated reduction of the tetrazolium salt, MTT. An initial slower phase (lag) in the time-course of the reaction was observed and analyzed. The results were as follows. (1) The time lag in the assay of the D-lactate dehydrogenase was eliminated by preincubating the membranes with PMS plus D-lactate, with PMS plus succinate, or with PMS plus NADH (conditions which implicated PMS reduction). (2) When the D-lactate dehydrogenase was assayed by another method based on the measurement of the pyruvate formed, neither was a time lag observed nor was the enzyme activity affected by membrane preincubation with PMS plus D-lactate. (3) Although the superoxide radical was involved in MTT reduction, this radical seemed not to participate in the generation of the time lag. (4) Membranes whose D-lactate dehydrogenase activity had previously been destroyed by heating at 80 degrees C for 1 min, were able to prolong the time lag in MTT reduction when added to the assay medium for the D-lactate dehydrogenase from untreated membranes, whereas membranes previously heated at 100 degrees C instead of 80 degrees C did not have this effect. It was concluded that the E. coli membranes interfered in the dehydrogenase assay based on the PMS-mediated reduction of MTT. The time lag was interpreted as a period during which the interfering substance reacted with reduced PMS inhibiting the reduction of MTT.

A simple method for the measurement of the hemolytic power of crude snake venoms.

La accion citolitica de sustancias simples y de agentes biologicos complejos puede ser descrita por ecuaciones tipo Hill. Se propone la medicion del poder hemolitico de venenos de serpientes en terminos de la disminucion de la accion litica en una dilucion 1:10. La ventaja de este procedimiento es que el poder citolitico es una funcion de las propriedades bioquimicas del sistema, mas que de la concentracion de los principios activos. Se muestran los poderes hemoliticos de algunos venenos de serpientes sobre eritrocitos humanos O Rh(+)