Persistence of four s-triazine herbicides in river, sea and groundwater samples exposed to sunlight and darkness under laboratory conditions

The persistence of terbuthylazine, simazine, atrazine and prometryn (s-triazine herbicides) was studied in sea, river and groundwaters during long-term laboratory incubation (127 days) under different laboratory conditions (light-darkness at 20 degrees C). Analysis of herbicides was performed by GC-NPD and their identity was confirmed by GC-MSD. A micro on-line method for the isolation of herbicide residues was used. The results showed that light had little effect on the removal of the four herbicides in riverwater but had a marked effect on their removal from sea and groundwater. Surprisingly, this removal appeared to be inversely proportional to the concentration of dissolved organic materials. In general, the degradation order was similar in sea and riverwaters; simazine was the most readily degraded compound (t(1/2)= 29-49 days), while terbuthylazine was the most persistent with the longest half-lives (76-331 days). In groundwater, terbuthylazine also showed greater persistence but prometryn was the compound with a fastest degradation rate, half-lives ranged from 88 days for prometryn to approximately 100 days for the other three compounds in light conditions and 263-366 days for prometryn and terbuthylazine, respectively, in darkness. Only for terbuthylazine was the remaining percentage at the end of the experiment higher than 50% under light conditions in riverwater, while in the other cases, the remaining percentage varied from 7 to 43% for simazine in seawater and atrazine in groundwater, respectively. Finally, a greater persistence was observed in groundwater for the four compounds.     

Effect of climate on the trophic structure of temperate forested streams. a comparison of Mediterranean and Atlantic streams

Climate affects many aspects of stream ecosystems, although the presence of riparian forests can buffer differences between streams in different climatic settings. In an attempt to measure the importance of climate, we compared the seasonal patterns of hydrology, input and storage of allochthonous organic matter, and the trophic structure (abundance of algae and macroinvertebrates) in two temperate forested streams, one Mediterranean, the other Atlantic. Hydrology played a leading role in shaping the trophic structure of both streams. Frequency and timing of floods and droughts determined benthic detritus storage. Inputs and retention of allochthonous organic matter were higher in the Atlantic stream, whereas chlorophyll concentration was lower because of stronger light limitation. Instead, light availability and scour of particulate organic matter during late winter favoured higher chlorophyll concentration in the Mediterranean stream. As a result, in the Mediterranean stream grazers were more prevalent and consumers showed a higher dependence on autotrophic materials. On the other hand, the Atlantic stream depended on allochthonous materials throughout the whole study period. The overall trophic structure showed much stronger seasonality in the Mediterranean than in the Atlantic stream, this being the most distinctive difference between these two types of temperate streams. The different patterns observed in the two streams are an indication that climatic differences should be incorporated in proper measurements of ecosystem health.     

Antichagasic,Leishmanicidal, and Trichomonacidal Activity of 2‐Benzyl‐5‐nitroindazole‐Derived Amines

Three different series of new 5‐nitroindazole derivatives—1‐(ω‐aminoalkyl)‐2‐benzylindazolin‐3‐ones (series A ; ten compounds), 3‐(ω‐aminoalkoxy)‐2‐benzylindazoles (series B ; four compounds) and 3‐alkylamino‐2‐benzylindazoles (series C ; five compounds)—have been synthesized and evaluated against the protozoan parasites Trypanosoma cruzi, Leishmania amazonensis, and Trichomonas vaginalis: etiological agents of Chagas disease, cutaneous leishmaniasis, and trichomoniasis, respectively. Many indazoles of series A , B , and C were efficient against T. cruzi. Some compounds in series A , after successfully passing the preliminary screening for epimastigotes, exhibited activity values against amastigotes of several T. cruzi strains that were better than or similar to those shown by the reference drug benznidazole and displayed low nonspecific toxicity against mammalian cells. On the other hand, preliminary studies against promastigotes of L. amazonensis showed high leishmanicidal activity for some derivatives of series A and C . With regard to activity against T. vaginalis, some indazoles of series B and C were rather efficient against trophozoites of a metronidazole‐sensitive isolate and showed low nonspecific toxicities toward Vero cell cultures. Additionally, some of these compounds displayed similar activity against metronidazole‐sensitive and resistant isolates, showing the absence of cross‐resistance between these derivatives and the reference drug.     

Ni–W coatings electrodeposited on carbon steel: Chemical composition, mechanical properties and corrosion resistance

Hard, ductile and adherent nanostructured Ni–W coatings were electrodeposited on carbon steel from electrolyte solutions containing sodium tungstate, nickel sulfate and sodium citrate, using different current pulse programs. Current pulse frequency was the dominant factor to define chemical composition, grain size, thickness and hardness. According to the electrodeposition conditions the deposited coatings showed 15–30 at% W, the grain size ranged from 65 to 140 nm, and the hardness varied from 650 to 850 Hv. Tungsten carbide also present in the coating contributed to its hardness. The corrosion resistance of the Ni–W coated steel was tested by potentiodynamic polarization in a neutral medium containing sulphate ions. The Ni–W coating protected the carbon steel from localized corrosion induced by sulphate anions.     

Fuzzy logic modeling and control of steel rod quenching after hot rolling

Reinforced concrete rod produced by European Community countries must comply with standards that establish minimum strength and tensile properties along with other technological and geometrical characteristics; however, possible variability within the assigned limits is not specified. Consequently, a number of manufacturing methods are now used, with the result that over time the mechanical properties of these products vary widely. Increased competition has led to the development of new procedures incorporating both process and quality control. One example is a process based on the heat treatment undergone by the metal bars leaving the final stand of the rolling mill train. In this way, the mechanical and technological properties can be graduated, thereby enhancing strength (particularly yield point) without altering the deformability of the material. This procedure does away with the need to alter the chemical composition of the steel used to manufacture the rods. Process adjustment still relies on the experience of the production manager, however. This paper examines the possibility of applying fuzzy logic computer techniques to the heat treatment process in order to render it more rational and independent of operator unreliability.     

Integrated biological and chemical analysis of organochlorine compound pollution and of its biological effects in a riverine system downstream the discharge point

Pollution in riverine systems, along with its biological effects, may propagate downstream even at considerable distances. We analyzed the organochlorine compound (OC) pollution in a section of the low Ebro River (Northeast Spain) downstream a long-operating chlor-alkali plant. Maximal levels of OCs and of their associated dioxin-like biological activity occurred in residue samples from the plant, and persisted in river sediments some 40 km downstream (Xerta site). Biological analysis at multiple organization levels in local carp (Cyprinus carpio, EROD, Cyp1A mRNA expression in the liver, hepatosomatic index, condition factor, and micronuclei index in peripheral blood) showed a similar pattern, with a maximal impact in Ascó, few kilometers downstream the plant, and a clear reduction at Xerta. This combination of chemical, molecular, cellular and physiological data allowed the precise assessment of the negative impact of the chlor-alkali plant on the quality of river sediments and on fish, and suggests that sediments may be a reservoir for toxic substances even in dynamic environments like rivers.     

Comparison of peristrophic multiplexing and a combination of angular and peristrophic holographic multiplexing in a thick PVA/acrylamide photopolymer for data storage

Two different types of multiplexing are used to store 90 holograms at the same location in a polyvinyl alcoholacrylamide photopolymer material. In the first, the 90 holograms are stored using only peristrophic multiplexing, whereas in the second a combination of angular and peristrophic multiplexing is used. The results (diffraction efficiency and dynamic range, M#) obtained with these two multiplexing techniques are compared. With the first, the dynamic range was M# = 13 and with the second M# = 8. An exposure schedule method is used to calculate the exposure time necessary to store the holograms with a more uniform, higher diffraction efficiency.     

Multiplexed holographic data page storage on a polyvinyl alcohol/acrylamide photopolymer memory

Holographic data pages were multiplexed in different thickness layers of a polyvinyl alcohol/acrylamide photopolymer. This material is formed of acrylamide photopolymers, which are considered interesting materials for recording holographic memories. A liquid crystal device was used to modify the object beam and store the data pages. A peristrophic multiplexing method is used to store a large number of data pages in the same spot in the material. The bit error rate was calculated fitting the histograms of the images to determine what parameters improve the quality of the images.