Polarographic determination and aqueous potentiometric titration of cimetidine in tablets

A method is described which uses the direct current (dc) polarographic behavior of cimetidine in a strong acid solution to determine this compound. The diffusional characteristics of the reduction wave of cimetidine in 1M HCl (about -0.8 V vs SCE) are shown, and their analytical usefulness was studied. This polarographic method was used to determine cimetidine in standard solutions ranging from 4 to 80 micrograms/mL with a coefficient of variation of 1.3%, and was further applied to the determination of cimetidine in tablets. The results obtained by the dc polarographic method agree with those obtained by an aqueous potentiometric titration of cimetidine with HClO4 and estimation of the end point by the Gran graphic method.     

Additional notes to the cheklist of cuban cultivated plants (1)

Summary New information is presented for the checklistof Cuban cultivated plants (Esquivel et al. 1989). 79 new species were included. For another 50 species new items are indicated.

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Ergänzende Notizen zur Liste der kubanischen Kulturpflanzen (1)

Zusammenfassung Neue Informationen zur Liste der kubanischen Kulturpflanzen (Esquivel et al. 1989) werden gegeben. 79 Arten wurden neu aufgenommen. Für weitere 50 Arten werden ergänzende Angaben gebracht.

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(I)

(Esquivel et al. 1989). 79 . 50 .

     

Volatile constituents of Chinese chive (Allium tuberosum Rottl. ex Sprengel) and rakkyo (Allium chinense G. Don)

Volatile components were isolated from Chinese chive and rakkyo by simultaneous steam distillation-solvent extraction and analyzed by GC and GC-MS. Sulfur compounds account for 88 and 94% of the total volatiles in the isolated extract of Chinese chive and rakkyo, respectively. In addition to the sulfur compounds commonly reported in the genus Allium, 27 novel volatile sulfur-containing components were found in the isolated extracts of both species. Among them were a sulfide, disulfides, trisulfides, and tetrasulfides with ethyl, butyl, and pentyl groups.     

Influence of tillage, crop rotation and nitrogen fertilization on soil organic matter and nitrogen under rain-fed Mediterranean conditions

The long-term effects of cropping systems and management practices on soil properties provide essential information for assessing sustainability and environmental impact. Field experiments were undertaken in southern Spain to evaluate the long-term effects of tillage, crop rotation and nitrogen (N) fertilization on the organic matter (OM) and mineral nitrogen (N_min) contents of soil in a rain-fed Mediterranean agricultural system over a 6-year period. Tillage treatments included no tillage (NT) and conventional tillage (CT), crop rotations were of 2 yr with wheat (Triticum aestivum L.)-sunflower (Helianthus annuus L.) (WS), wheat-chickpea (Cicer arietinum L.) (WP), wheat-faba bean (Vicia faba L.) (WB), wheat-fallow (WF), and in addition, continuous wheat (CW). Nitrogen fertilizer rates were 50, 100, and 150 kg N ha⁻¹. A split-split plot design with four replications was used. Soil samples were collected from a depth of 90 cm at the beginning of the experiment and 6 yr later. Soil samples were also collected from a depth of 30 cm after 4 yr. These samples, like those obtained at the beginning of the experiment, were subjected to comprehensive physico-chemical analyses. The soil samples that were collected 6 yr later were analyzed for OM, NH₄⁺---N and NO₃⁻---N at the 0–30, 30–60 and 60–90 cm soil depths. The tillage method did not influence the OM or N_min contents of the soil, nor did legume rotations increase the OM content of soil relative to CW. A longer period may have been required for differences between treatments to be observed owing to the small amount of crop residue that is returned to soil under rain-fed conditions of semi-arid climates. The WF rotation did not raise the N_min content of the soil relative to the other rotations. The consistent significant interaction between tillage and crop rotation testifies to the differential effect of the management system on the OM content and N status of the soil. The ammonium levels clearly exceeded those of NO₃⁻---N throughout the soil profile. The high N_min content of the soils reveals the presence of abundant N resources that should be borne in mind in establishing N fertilization schemes for crops under highly variable climatic conditions including scant rainfall such as those of the Mediterranean region.     

Have the Flowers,Fruitlets, Ripe Fruit and Leaves of Apples Cultivars Similar Compositions of Phenolic and Antioxidant Capacity?

Total and specific phenolic compounds and antioxidant capacity were quantified over two seasons in flowers, leaves, fruitlets, and ripe fruit at harvest of the apple cultivars ‘Brookfield’, ‘Granny Smith’ and ‘Fuji’, as well the crabapple cultivars ‘Hillary’ and ‘Manchurian’. The results showed that leaves had the highest phenol concentrations and antioxidant capacity. Phenolic and antioxidant content was progressively lower from flowers, fruitlets, and ripe harvested fruit. There were high concentrations of phloridzin in flowers and leaves, while concentrations were lower in fruitlets, peel, and entire fruit at harvest. The phenolic compound with the highest concentration in peel was quercetin glycoside, while in the entire fruit it was flavanols. The studied crabapple cultivars did not present differences between them in phenolic compounds and antioxidant capacity.

     

Tannins from barks of Pinus caribaea protect Escherichia coli cells against DNA damage induced by gamma-rays

This work was aimed to evaluate genotoxicity and antigenotoxicity activity against gamma-rays of a tannin fraction obtained from barks of Pinus caribaea, as well as to elucidate the antigenotoxic mechanisms involved in radioprotection by using different approaches as pre-, co- and post-irradiation cell treatments with plant extract. The tannin fraction was not genotoxic to Escherichia coli cells in experiments using different exposure times. This extract was antigenotoxic against gamma-rays when the cells were pre- or co-treated with this extracts, but not during post-irradiation treatments, suggesting a possibly antigenotoxic action through free radical scavenging mechanisms. The results are discussed in relation to the chemopreventive and therapeutic potential of the studied plant species.     

Are standing dead trees (snags) suitable as climate proxies? A case study from the central Scandinavian Mountains

Standing dead trees (snags) play important roles in forest ecology by storing carbon as well as providing habitats for many species. Moreover, snags preserved for hundreds of years can provide useful data to extend tree-ring chronologies used for climatological and ecological studies beyond the lifespans of living trees. Here we examined the growth patterns of Scots pine snags from the central Scandinavian Mountains, in relation to still living trees. Using changes point analyses, we showed that a majority (74%) of the snags displayed significant negative growth changes prior (on average 17 years) to death. Change points around the same years were also seen in living trees, but they recovered their growth. The average growth reduction of snags showing negative growth changes before death was 46%. In most cases the final growth change points coincided with very cold summers, or to a lesser degree to period of cool summers. It was suggested that pines ending up as snags were less resilient than the trees which continued living, and thus not able to recover after cold summer events. Since the snag growth reductions prior to death were partly unrelated to climate, care should be taken when using such data in dendroclimatological studies.     

Phytostabilization Ability of <Emphasis Type="Italic">Baccharis linearis</Emphasis> and Its Relation to Properties of a Tailings-Derived Technosol

Spontaneous colonization of mine tailing dams by plants is a potential tool for phytostabilization of such reservoirs. However, the physical and chemical properties of each mine tailings deposit determine the success of natural plant establishment. The plant Baccharis linearis is the main native nanophanerophyte species (evergreen sclerophyllous shrub) that naturally colonizes abandoned copper tailings dams in arid to semiarid north-central Chile. This study compare growth of B. linearis against the physical and chemical properties of a Technosol derived from copper mine tailings. Five sites inside the deposit were selected based on B. linearis vegetation density (VD), at two soil sampling depths under the canopy of adult individuals. Physical and chemical properties of tailings samples and nutrient concentrations in tailings and plants were each determined. Some morphological features of the plants (roots and aerial parts) were also quantified. There were significant differences in soil available water capacity (AW) and relative density (Rd) at different VD. Sites with low AW and high Rd had lower nutrient concentrations and higher Zn content in tailings, decreased infection by arbuscular mycorrhizal fungi, and increased fine root abundance and root hair length in individual plants. In contrast, higher AW, which was positively correlated with fine particles and organic matter content, had a positive effect on vegetation coverage, increased N and P contents in tailings, and increased N contents in leaf tissues, even when available N and P levels in tailings were low. Multiple constraints, such as low AW, N, P, and B contents and high Zn concentrations in the tailings restricted vegetation coverage, but no phenotypic differences were observed between individuals. Thus, in order to promote dense coverage by B. linearis, water retention in these tailings must be improved by increasing colloidal particles (organic and/or inorganic) contents, which have a positive effect on colonization by this species.     

Episodic recruitment of young Prochilodus lineatus (Valenciennes, 1836) (Characiformes: Prochilodontidae) during high discharge in a floodplain lake of the River Paraná, Argentina

Prochilodus lineatus (Val.) is one of the main target species of South American freshwater fisheries. The following null hypotheses regarding juvenile recruitment of P. lineatus were tested: (a) recruitment is not determined by variations in larval abundance and (b) recruitment is not determined by variations in discharge. For this purpose, variations in abundance of larvae in main channel drift and monthly captures of juveniles in a floodplain lake of the River Paraná were examined weekly between 2009 and 2016. Mean annual abundances of larval densities and CPUE of juveniles were correlated with a set of hydrometric variables. A positive correlation was found between the abundance of juveniles with high and persistent flood pulses. By contrast, larval abundance was not correlated with juvenile abundance. Pronounced contrast was found in the recruitment of P. lineatus between years of high and low discharge, which supports the hypothesis that floods are the main determining factor for recruitment of this species.     

Potential impacts of projected sea‐level rise on sea turtle rookeries

• 1. Projected sea‐level rise (SLR) is expected to cause shoreline erosion, saline intrusion into the water table and inundation and flooding of beaches and coastal areas. Areas most vulnerable to these physical impacts include small, tropical low‐lying islands, which are often key habitat for threatened and endemic species, such as sea turtles.
• 2. Successful conservation of threatened species relies upon the ability of managers to understand current threats and to quantify and mitigate future threats to these species. This study investigated how sea‐level rise might affect key rookeries (nesting grounds) (n=8) for the northern Great Barrier Reef (nGBR) green turtle population, the largest green turtle population in the world.
• 3. 3‐D elevation models were developed and applied to three SLR scenarios projected by the IPCC 2007 and an additional scenario that incorporates ice melting. Results indicate that up to 38% of available nesting area across all the rookeries may be inundated as a result of SLR.
• 4. Flooding, as a result of higher wave run‐up during storms, will increase egg mortality at these rookeries affecting the overall reproductive success of the nGBR green turtle population. Information provided will aid managers to prioritize conservation efforts and to use realistic measures to mitigate potential SLR threats to the nGBR green turtle population. Copyright © 2009 John Wiley & Sons, Ltd.