Search results for "Indicator"

Chromatographic separation of chlorthalidone enantiomers using β-cyclodextrins as chiral additives

2000

Different beta-cyclodextrins have been tested as chiral additives in the mobile phase for the chromatographic analysis of chlorthalidone enantiomers in a C18 LiChrospher (125 x 4 mm I.D.) column. The effect on enantioresolution of different parameters was studied: composition of the mobile phase (percentage of organic solvent, type of buffer and pH), mobile phase flow-rate, and type and concentration of beta-cyclodextrin. A 25:75 mixture of methanol and 0.1 M phosphate buffer, pH 4, containing 2% triethylamine (v/v), and 12.5 mM beta-cyclodextrin, at a flow-rate of 0.8 ml/min, was found to be the best option for the resolution of chlorthalidone enantiomers. Under such conditions, linear cal…

Bibliometric analysis of publications by South African viticulture and oenology research centres

2012

We analysed the production, impact factor of, and scientific collaboration involved in viticulture and oenology articles associated with South African research centres published in international journals during the period 1990–2009. The articles under scrutiny were obtained from the Science Citation Index database, accessed via the Web of Knowledge platform. The search strategy employed specific viticulture and oenology terms and was restricted to the field ‘topic’. The results showed that 406 articles were published during the review period, with the most number of publications being in the South African Journal of Enology and Viticulture (n = 34), American Journal of Enology and Vit…

Automated pre-column derivatization of amines in biological samples with dansyl chloride and with or without post-column chemiluminescence formation …

1999

On-line automation of two different liquid chromatographic procedures, a pre-column derivatization system and a pre- and post-column system, in order to generate chemiluminescence is reported. Dansyl chloride (Dns-Cl) was used as a pre-column reagent to form fluorophores and bis(2,4,6-trichlorophenyl) oxalate (TCPO) and hydrogen peroxide (H2O2) as a post-column reagent to generate chemiluminescence. This procedure is based on the employment of a primary column packed with C18 material inserted in a multi-dimensional assembly for sample clean-up and derivatization with Dns-Cl. The dansyl derivatives formed are transferred and separated in a LiChrospher 100 RP18 analytical column (125 x 4 mm …

Hot spots, indicator taxa, complementarity and optimal networks of taiga

2000

If hot spots for different taxa coincide, priority-setting surveys in a region could be carried out more cheaply by focusing on indicator taxa. Several previous studies show that hot spots of different taxa rarely coincide. However, in tropical areas indicator taxa may be used in selecting complementary networks to represent biodiversity as a whole. We studied beetles (Coleoptera), Heteroptera, polypores or bracket fungi (Polyporaceae) and vascular plants of old growth boreal taiga forests. Optimal networks for Heteroptera maximized the high overall species richness of beetles and vascular plants, but these networks were least favourable options for polypores. Polypores are an important gro…

Benthic foraminifera as an innovative proxy for pollution monitoring, impact and risk assessment of marine ecosystems: experimental studies to evalua…

2013

Ellenberg Indicator Values for the vascular flora alien to Italy

2018

Studies to date about plants alien to Italy have had limited focus on the ecology of this component of the flora. Ellenberg's indicator values are a useful tool to delineate the relationship between plants and environment, recognizing for each species a functional role as biological indicator; these values have been proposed for estimating the influence of the main environmental factors in determining flora and vegetation changes on a specific surface area. This contribution includes a list of 1206 taxa of plants naturalized in at least one administrative region or casual in at least three regions of Italy. In addition, some methodological considerations on the attribution and use of Ellenb…

The morphological diversity within a species can obscure the correct identification

2022

Critical points of various diagnostic characters and a paucity of information relating to the geographical distribution of several marine species can hinder real species delimitation, particularly if they are supposed to be cosmopolitan. Such constraints characterize many amphipod species and are mainly due to the variation in morphological characters during growth. Specifically, the benthic filter-feeding corophiid Cheiriphotis mediterranea Myers, 1983 displays different shapes for the male gnathopod 2 as it grows. This variation has hitherto never been described but an extensive sampling has provided us with the opportunity of studying it in detail. More than six thousand individuals, bel…

Risposta dei bioindicatori della qualità del suolo alla diversa fertilizzazione di un aranceto nell’ Italia Meridionale

2013

Lo scopo della ricerca è stato quello di valutare i cambiamenti indotti dalle diverse tipologie di fertilizzazione sui parametri chimici e biologici di un suolo. Il suolo dell’agro di Lentini (SR, Sicilia), coltivato ad arancio da oltre 50 anni, a partire dal 1995 secondo il metodo biologico , omogeneo per portinnesto e cultivar, è stato addizionato con 4 diversi tipi di fertilizzanti (pollina, minerale, compost da pastazzo e letame). Quattro profili di suolo, ciascuno per tipo di fertilizzazione, sono stati campionati e studiati secondo la sequenza degli orizzonti genetici. In totale 18 campioni orizzonte-specifici di suolo sono stati prelevati e sottoposti ad analisi per valutare il conte…

Soil carbon quality and nitrogen fertilization structure bacterial communities with predictable responses of major bacterial phyla

2014

Abstract Agricultural practices affect the soil ecosystem in multiple ways and the soil microbial communities represent an integrated and dynamic measure of soil status. Our aim was to test whether the soil bacterial community and the relative abundance of major bacterial phyla responded predictably to long-term organic amendments representing different carbon qualities (peat and straw) in combination with nitrogen fertilization levels and if certain bacterial groups were indicative of specific treatments. We hypothesized that the long-term treatments had created distinctly different ecological niches for soil bacteria, suitable for either fast-growing copiotrophic bacteria, or slow-growing…

The rotifer community and its functional role in lakes of a neotropical floodplain

2014

Aquatic communities vary depending on local factors, such as environmental conditions and biological interactions and regional factors, such as the hydrological regime in floodplains. This study analyzed the community structure of rotifers and their secondary production in two lakes of an Upper Parana River floodplain (Brazil) differing in their hydrology: one connected to the river and the other isolated. Integrated samples of the water column were collected daily during 15 days in the low and high water periods. Three statistical methods, ANOVA, MRT, and IndVal were applied to distinguish the structure, biomass, and secondary production of their rotifer communities. The rotifer fauna was …