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See detailMacromolecular engineering of polylactones and polylactides. 4. Mechanism and kinetics of lactide homopolymerization by aluminum isopropoxide
Dubois, Philippe; Jacobs, R.; Jérôme, Robert ULg et al

in Macromolecules (1991), 24(9), 2266-2270

Aluminum isopropoxide is an effective initiator for the polymerization of lactides in toluene at 70-degrees-C. The ring-opening polymerization proceeds through a "coordination-insertion" mechanism and ... [more ▼]

Aluminum isopropoxide is an effective initiator for the polymerization of lactides in toluene at 70-degrees-C. The ring-opening polymerization proceeds through a "coordination-insertion" mechanism and selective rupture of the acyl oxygen bond of the monomer. A kinetic study has shown that the polymerization is first order in both the monomer and initiator. The polymerization is typically "living" until a molecular weight of ca. 90 000 is reached. At higher temperatures (100-degrees-C), inter- and intramolecular transesterification reactions are responsible for a limitation in the molecular weight of the growing chains. In toluene, at 70-degrees-C, each alkoxide of the aluminum isopropoxide participates in the polymerization. Any molecular weight below 90 000 can accordingly be predicted on the basis of the monomer/Al molar ratio, and the polydispersity is rather narrow (1.1-1.4). [less ▲]

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See detailMacromolecular engineering of polylactones and polylactides. 5. Synthesis and characterization of diblock copolymers based on poly-ε-caprolactone and poly(L,L or D,L)lactide by aluminum alkoxides
Jacobs, C.; Dubois, Philippe; Jérôme, Robert ULg et al

in Macromolecules (1991), 24(11), 3027-3034

Aluminum isopropoxide is known to be an effective initiator for the ring-opening polymerization of lactides (D,L and L,L) and epsilon-caprolactone (epsilon-CL). For a question of mutual reactivity, the ... [more ▼]

Aluminum isopropoxide is known to be an effective initiator for the ring-opening polymerization of lactides (D,L and L,L) and epsilon-caprolactone (epsilon-CL). For a question of mutual reactivity, the sequential polymerization of these two comonomers can only be achieved when epsilon-CL is first polymerized followed by the lactide. Formation of a large amount of homo PLA is however observed and has been attributed to a great difference in the mean degree of association of aluminum alkoxides in toluene in the presence of epsilon-CL and LA. In toluene, the mean number (n) of active sites per Al(O(i)Pr)3 molecule jumps from 1 to 3 when epsilon-CL is substituted by LA. The addition of a small amount of an alcohol, like 2-propanol, is effective in preventing the aluminum alkoxide from associating, and n is then 3 whatever the monomer used. 2-Propanol participates in the polymerization of epsilon-CL and LA as supported by a decrease in the molecular weight of the final polymer in relation to the molar amount of added alcohol. This means that the alcohol molecules are rapidly exchanged with the alkoxide groups on Al. Under such conditions, the formation of pure diblock copolymers P(epsilon-CL-b-LA) is reported. Another successful strategy for the synthesis of the diblock copolymer consists in using an Al derivative that bears only one alkoxide group to initiate the polymerization of the two cyclic esters. In this regard, a diethylaluminum alkoxide is of great value, particularly the ethoxide one. A third, conceptually similar, approach to the synthesis of P(epsilon-CL-b-LA) copolymers relates to the reaction of a performed hydroxy-terminated PCL with triethylaluminum and the use of that macroinitiator in the ring-opening polymerization of the lactide. [less ▲]

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See detailMacromolecular engineering of polylactones and polylactides. 7. Structural analysis of copolyesters of epsilon-caprolactone and L- of D,L-lactide initated by Al(OiPr)3
Vanhoorne, Pierre; Dubois, Philippe; Jérôme, Robert ULg et al

in Macromolecules (1992), 25(1), 37-44

Copolymerization of mixtures of epsilon-caprolactone (epsilon-CL) and D,L- or L-lactide has been initiated by aluminum isopropoxide. On the basis of the monomer reactivity ratios and assuming that no side ... [more ▼]

Copolymerization of mixtures of epsilon-caprolactone (epsilon-CL) and D,L- or L-lactide has been initiated by aluminum isopropoxide. On the basis of the monomer reactivity ratios and assuming that no side reaction occurs, tapered copolymers should be formed particularly when D,L-lactide is the comonomer rather than L-lactide. The sequential distribution of the comonomers has been analyzed by an original method based on the quantitative measurement of the carbonyl C-13 signals. Comparison of the experimental and the theoretical distributions clearly shows that transesterification reactions occur during copolymerization through both intra- and intermolecular mechanisms. Gel permeation chromatography and differential scanning calorimetry data support that conclusion. The D,L-lactide-based copolymers have however a more blocky structure than those containing L-lactide, and they are also less sensitive to transesterification reactions. [less ▲]

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See detailMacromolecular engineering of polylactones and polylactides. 8. Ring-opening polymerization of ε-caprolactone initiated by primary amines and trialkylaluminum
Dubois, Philippe; Degée, Philippe; Jérôme, Robert ULg et al

in Macromolecules (1992), 25

Whenever added with triethylaluminum, primary amines have been found to be effective initiators for epsilon-caprolactone polymerization in both toluene and THF at 40°C. The IR and NMR analysis of the ... [more ▼]

Whenever added with triethylaluminum, primary amines have been found to be effective initiators for epsilon-caprolactone polymerization in both toluene and THF at 40°C. The IR and NMR analysis of the polyester has supported a polymerization mechanism proceeding through a "coordination-insertion" pathway and the selective rupture of the acyl-oxygen bond of the monomer. The alkylaluminum activates the carbonyl group of the monomer and accordingly favors the nucleophilic addition of the amine, which is the actual initiation step. Propagation is typically a living process, and the molecular weight distribution is controlled by both AlEt3/amine molar ratio and solvent As an extension of that mechanism, diethylaluminum omega-amino alkoxide has been prepared on purpose and successfully used as an initiator for the synthesis of α,ω-dihydroxypoly(ε-caprolactone). [less ▲]

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See detailMacromolecular engineering of polylactones and polylactides. 9. Synthesis, characterization, and applications of omega-primary amine poly(ε-caprolactone)
Degée, Philippe; Dubois, Philippe; Jérôme, Robert ULg et al

in Macromolecules (1992), 25

The synthesis and use of functional diethylaluminum alkoxides (Et2AlORX) as initiators for the ring-opening polymerization of ε-caprolactone have been investigated as a possible strategy to prepare omega ... [more ▼]

The synthesis and use of functional diethylaluminum alkoxides (Et2AlORX) as initiators for the ring-opening polymerization of ε-caprolactone have been investigated as a possible strategy to prepare omega-primary amino poly(ε-caprolactone) (PCL). In a first approach, an initiator containing ethylphthalimide as the functional-RX group has been synthesized. That protected amino group has been successfully attached at the end of PCL chains. The conversion of the phthalimide end group into a primary amine has however failed, whatever the experimental conditions. In an alternative approach, an alkyl bromide has been considered as the functional group to be attached to PCL chains, via the appropriate initiator. The end functionalization was quantitative and the bromo end group converted into an azido group which was subsequently reduced to the expected primary amine. Omega-primary amino PCL has proved to be an effective macroinitiator for the ring-opening polymerization of γ-benzylglutamate N-carboxy anhydride with the formation of a poly(caprolactone-b-peptide) diblock copolymer. [less ▲]

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See detailMacromolecular engineering of polylactones and polylactides. XXV. Synthesis and characterization of bioerodible amphiphilic networks and their use as controlled drug delivery systems
Barakat, Ibrahim; Dubois, Philippe ULg; Grandfils, Christian ULg et al

in Journal of Polymer Science. Part A, Polymer Chemistry (1999), 37(14), 2401-2411

Well-defined ,-methacryloyl poly--caprolactone (PCL) and poly(d,l)-lactide P(D,L)LA dimacromonomers have been synthesized by living ring-opening polymerization of the parent monomers initiated by ... [more ▼]

Well-defined ,-methacryloyl poly--caprolactone (PCL) and poly(d,l)-lactide P(D,L)LA dimacromonomers have been synthesized by living ring-opening polymerization of the parent monomers initiated by diethylaluminum 2-hydroxyethylmethacrylate (Et2AlO(CH2)2OC(O)C(CH3)CH2) and terminated by reaction of the propagating Al alkoxide groups with methacryloyl chloride. These dimacromonomers have been copolymerized with a hydrophilic comonomer, i.e., 2-hydroxyethylmethacrylate, in bulk at 65°C by using benzoyl peroxide as a free-radical initiator. The swelling ability of the amphiphilic PHEMA/PCL or P(D,L)LA networks has been investigated in both aqueous and organic media. Effect of network composition and molecular weight of the dimacromonomer on the swelling kinetics and the equilibrium solvent uptake has been studied. Lipophilic dexamethasone acetate and the hydrophilic sodium phosphate counterpart have been incorporated into the amphiphilic gels and their release has been studied in relation to the gel characteristics. [less ▲]

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See detailMacromolecular engineering to the service of advanced drug delivery systems
Jérôme, Christine ULg

Conference (2010, September 16)

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See detailMacromolecular engineering to the service of advanced drug delivery systems
Jérôme, Christine ULg

Conference (2010, October 25)

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See detailMacronutrient composition of three cucurbit species cultivated for seed consumption in Côte d'Ivoire
Loukou, A. L.; Gnakri, D.; Djè, Y. et al

in African Journal of Biotechnology (2007), 6(5), 529-533

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See detailMacronutrients supply during Lactation and Infant Growth
Senterre, Thibault ULg; Rigo, Jacques ULg

in Symonds, M.; Ramsay, M. (Eds.) Maternal-Fetal Nutrition during Pregnancy and Lactation (2010)

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See detailMacrophage migration inhibitory factor (MIF) expression in human glioblastomas correlates with vascular endothelial growth factor (VEGF) expression
Munaut, Carine ULg; Boniver, Jacques ULg; Foidart, Jean-Michel ULg et al

in Neuropathology & Applied Neurobiology (2002), 28(6), 452-460

Macrophage migration inhibitory factor (MIF) is a peptide released upon hypothalamo-pituitary stimulation that acts as a potent endogenous antagonist of the glucocorticoid inhibition of acute inflammatory ... [more ▼]

Macrophage migration inhibitory factor (MIF) is a peptide released upon hypothalamo-pituitary stimulation that acts as a potent endogenous antagonist of the glucocorticoid inhibition of acute inflammatory response and subsequent antigen-specific response. MIF also sustains tumour growth as it promotes angiogenesis, overcomes p53-mediated cell growth arrest and inhibits tumour-specific immune responses. Using quantitative reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry, we studied MIF expression in 35 human glioblastomas and two normal brains. We compared these results with the expression of vascular endothelial growth factor (VEGF), the most potent angiogenic factor in glioblastomas. We detected MIF in normal cortical neurons and glial cells. All glioblastomas were positive for MIF mRNA with expression levels similar to or higher than those of normal brain. MIF immunoreactivity was seen mainly in tumour cells and less frequently in hyperplastic endothelial cells. The expressions of MIF and VEGF mRNA were strongly correlated (P < 0.0001). Our results demonstrate the expression of MIF in human glioblastomas, and indicate a close relationship with VEGF expression. This is of particular interest given the potential modulation of MIF by glucocorticosteroids. [less ▲]

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See detailMacrophages and Tumor Necrosis Factor Alpha in Toxic Epidermal Necrolysis
Paquet, Philippe ULg; Nikkels, Arjen ULg; Arrese Estrada, Jorge ULg et al

in Archives of Dermatology (1994), 130(5), 605-608

BACKGROUND: We studied the immunopathologic characteristics of five cases of toxic epidermal necrolysis by using a large panel of antibodies. OBSERVATIONS: The pattern and amount of the inflammatory cell ... [more ▼]

BACKGROUND: We studied the immunopathologic characteristics of five cases of toxic epidermal necrolysis by using a large panel of antibodies. OBSERVATIONS: The pattern and amount of the inflammatory cell infiltrate varied according to the stage of the disease. The main constant feature was the prominent involvement of the monocyte-macrophage lineage, including factor XIIIa+HLA-DR+ dendrocytes and CD68+ Mac 387+ macrophages, before and during the epidermal necrosis. The number of CD4+ and CD8+ lymphocytes was comparatively small. This was associated with a dense labeling of the epidermis for tumor necrosis factor alpha. CONCLUSIONS: Cells of the monocyte-macrophage lineage largely outnumber lymphocytes in the lesions of toxic epidermal necrolysis. Tumor necrosis factor alpha is likely a major cytokine that is responsible for necrosis. [less ▲]

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See detailLes macrophages interstitiels, gardiens de l'homeostasie immune pulmonaire.
Bedoret, Denis; Bureau, Fabrice ULg; Desmet, Christophe ULg

in Medecine Sciences : M/S (2010), 26(3), 229-31

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See detailMacrophyte biological index for rivers (MBIR) application for an ecological assessment of walloon rivers, prelilminary investigations.
Sossey Alaoui, Khadija ULg; Galoux, D.; Rosillon, Françis ULg

Conference (2009)

Samples were collected from 45 sites along the Walloon river network in 2007, in accordance with the Water Framework Directive (WFD, European Union, 2000), used to define the overall ecological status of ... [more ▼]

Samples were collected from 45 sites along the Walloon river network in 2007, in accordance with the Water Framework Directive (WFD, European Union, 2000), used to define the overall ecological status of rivers. Within each collected sample, macrophyte data were gathered at species level and the main water quality parameters were analyzed. This involved the use of two approaches: firstly, methods of ordination and classification (Principal Component Analysis and Multiple Factorial Analysis) and secondly, aquatic macrophyte community indexes. The Macrophyte Biological Index for Rivers (MBIR) was used to define the ecological status of the macrophyte community in response to eutrophication pressure. Four trophic qualities were detected in all the monitored stations: 56% of the sites showed a good trophic quality, with the Ardennes region in the leading position and only 2% of the sites showed a poor trophic quality. A Multiple Factorial Analysis (MFA) made it possible to regroup the species according to their ecological affinities and to specify their indicator values in relation to some abiotic parameters. As a result, a rivers typology was outlined based on this analysis. The dendrogram of the Hierarchical Cluster Analysis (HCA) gave three clusters determined by active variables of each compartment that defined functional parts of the Walloon network: Chiloscyphus polyanthos (L.) Corda, Rhynchostegium riparioides(Hedw.)C.Jens., Fontinalis squamosa(Hedw) and Ranunculus penicillatus (Dum.)Bb. showed an oligotrophic status and low mineralization in the Ardennes (GI), while P. pectinatus(Linne), Cladophora glomerata(Linnaeus)proved to be found more often in eutrophicated waters in the Region limoneuse (GIII). Pellia endvifolia (Dicks.)Dum, Fissidens crassipes(Br.Eur);Cinclidotus riparius (Web. & Mohr.) appeared in the Condroz and Famenne, rivers characterized by a high concentration of nitrogen (N-35. NO3-) (GII). [less ▲]

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See detailMacrophytes : limitations of using them to assess reservoir status according to the water framework directive
Sossey Alaoui, Khadija ULg; Rosillon, Francis ULg

Conference (2013, July)

Macrophytes are among the major groups of organisms that the Water Framework Directive (WFD) recommends should be used in assessing the status of reservoirs. The use of macrophytes in reservoir monitoring ... [more ▼]

Macrophytes are among the major groups of organisms that the Water Framework Directive (WFD) recommends should be used in assessing the status of reservoirs. The use of macrophytes in reservoir monitoring is still fairly limited and studies are needed on their inter-calibration and sources of variation. Many status assessment methods based on macrophyte communities have been defined for lakes, Nevertheless few of them have been tested for reservoirs. The purpose of the study is to highlight the limitations of using macrophytes to assess reservoir status according to the Water Framework Directive. An assessment of macrophyte composition and abundance and of water quality was carried out in seven Walloon reservoirs between 2010 and 2012. The main limitations of the macrophyte approach for assessing these reservoirs were: i) geographical features, ii) physical variables, iii) water chemistry and iiii) lack of ecological information on the various macrophytic groups, such as helophytes, algae and mosses. Few of the taxa occurring in the Walloon reservoirs have an indicator score for status assessment based on macrophyte communities. We used two assessment methods to test the relevance of using macrophyte communities to assess reservoir status: the Flanders (Belgium) method (BE-FL method) and the United Kingdom method (UK-method). The relationships between macrophyte metrics for both methods and nutrient enrichment were examined. Highly significant correlations were found between the chemical variables (O-P [mg P/l]); P tot (μg P/l); total hardness (°F), conductivity (μS/cm) and the trophic UK-metric (LMNI); and between it and the abundance of ‘Bl-FL disturbance indicators’ metric (V). The ‘UK group of macrophyte species’ metric does not provide direct information on the quality or degree of degradation of the environment from which the sample was taken. [less ▲]

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See detailLes macrophytes dans les ruisseaux de référence wallons: caractérisation des sites et typologie floristique
Sossey Alaoui, Khadija ULg; Galoux, Daniel; Rosillon, Francis ULg

in Colloque international des Macrophytyes: IRSTEA, Bordeaux 28-30 mai 2013 (2013, May 30)

La Directive européenne cadre 2000/60/CE sur l’eau a pour objectif l’atteinte du bon état écologique et du bon état chimique au sein des bassins hydrographiques, d'ici 2015. Pour établir l’état écologique ... [more ▼]

La Directive européenne cadre 2000/60/CE sur l’eau a pour objectif l’atteinte du bon état écologique et du bon état chimique au sein des bassins hydrographiques, d'ici 2015. Pour établir l’état écologique, la Directive impose de mesurer l’écart à la référence pour les indicateurs de la qualité biologique des cours d’eau (macroinvertébrés, diatomées, poissons, macrophytes et phytoplancton). L’élaboration d’une typologie macrophytique des ruisseaux de référence du bassin hydrographique de la Meuse, en Wallonie est l’objectif de l’étude. Les 50 sites étudiés font l’objet d’une caractérisation physico-chimique et mésologique et ensuite de relevés de végétation. Ceux-ci sont effectués sur des segments de cours d’eau de 100m de long et le recouvrement de chaque espèce est estimé selon une échelle d’abondance. Les ruisseaux étudiés peuvent être considérés comme le résultat d’un inventaire quasi exhaustif pour la Wallonie. Les plantes supérieures (hydrophytes), les mousses, les hépatiques, les macroalgues sont identifiées sur le terrain et au laboratoire à l’aide du binoculaire et du microscope. Le degré de la pente, l’altitude de la source et du site, l’occupation du sol, la géologie et certaines caractéristiques physico-chimiques de l’eau (ph, conductivité, teneur en calcium, magnésium et alcalinité) permettent de caractériser les stations. Six ensembles de ruisseaux avec leurs espèces caractéristiques sont mis en évidence par le "Two-Way Clustering" et "l’Indicator Species". L'analyse du déterminisme de distribution de la végétation dans les différents ensembles montre que ces derniers sont étroitement liés aux régions naturelles et leur typologie s’inscrit dans la typologie physique choisie par le Service public de Wallonie. [less ▲]

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See detailMacrophytes: Limitations of Using Them to Assess Reservoir Status According to the Water Framework Directive
Sossey Alaoui, Khadija ULg; Galoux, Daniel; Rosillon, Francis ULg

in International Journal of Water Sciences (2013)

Macrophytes are among the major groups of organisms that the Water Framework Directive (WFD) recommends should be used in assessing the status of natural lakes. The use of macrophytes in reservoir ... [more ▼]

Macrophytes are among the major groups of organisms that the Water Framework Directive (WFD) recommends should be used in assessing the status of natural lakes. The use of macrophytes in reservoir monitoring is still limited and further studies are needed on their inter-calibration and sources of variation. Many status assessment methods based on macrophyte <br />communities have been defined for lakes. Nevertheless, few of them have been tested for reservoirs. The purpose of the study is to highlight the limitations of using macrophytes to assess reservoir status according to the Water Framework Directive. <br />An assessment of macrophyte composition and abundance and of water quality was carried out in nine Walloon reservoirs between 2010 and 2012. The main limitations of the macrophyte approach for assessing these reservoirs were: i) geographical features; ii) physical variables; iii) lack of ecological information on the various macrophytic groups, such as helophytes, algae and mosses. We used two assessment methods to test the relevance of using macrophyte communities to assess reservoir status: the Flanders (Belgium) method (BE-FL method) and the United Kingdom method (UK method). The relationships between macrophyte metrics for both methods and nutrient enrichment were examined. Highly significant correlations were found between the chemical variables O-P [mg P/l]), Total P (µg P/l), Conductivity (µS/cm) and the trophic UK-metric (Lake Macrophyte Nutrient) (LMNI), as well as between such variables and the abundance of Bl-FL "disturbance indicators" metric(V). The UK "group of macrophyte species" metric provided limited information on the quality or degrees of degradation in the environment from which the sample was taken. [less ▲]

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See detailMacrophytes: limitations of using them to assess reservoir status according to the Water Framework Directive
Sossey Alaoui, Khadija ULg; Galoux, Daniel; Rosillon, Francis ULg

in Peer Review (2013)

Macrophytes are among the major groups of organisms that the Water Framework Directive (WFD) recommends should be used in assessing the status of natural Lakes. The use of macrophytes in reservoir ... [more ▼]

Macrophytes are among the major groups of organisms that the Water Framework Directive (WFD) recommends should be used in assessing the status of natural Lakes. The use of macrophytes in reservoir monitoring is still fairly limited and studies are needed on their inter-calibration and sources of variation. Many status assessment methods based on macrophyte communities have been defined for lakes, Nevertheless few of them have been tested for reservoirs. The purpose of the study is to highlight the limitations of using macrophytes to assess reservoir status according to the Water Framework Directive. An assessment of macrophyte composition and abundance and of water quality was carried out in nine Walloon reservoirs between 2010 and 2012. The main limitations of the macrophyte approach for assessing these reservoirs were: i) geographical features, ii) physical variables and iii) lack of ecological information on the various macrophytic groups, such as helophytes, algae and mosses. We used two assessment methods to test the relevance of using macrophyte communities to assess reservoir status: the Flanders (Belgium) method (BE-FL method) and the United Kingdom method (UK-method). The relationships between macrophyte metrics for both methods and nutrient enrichment were examined. Highly significant correlations were found between the chemical variables (O-P [mg P/l]); Total P (µg P/l); Conductivity (µS/cm) and the trophic UK-metric (Lake Macrophyte Nutrient) (LMNI); and between it and the abundance of Bl-FL "disturbance indicators’ metric (V). The UK "group of macrophyte species’ metric provide a limited information's on the quality or degree of degradation of the environment from which the sample was taken. [less ▲]

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See detailMacrophytic Distribution and Trophic State of Some Natural and Impacted Watercourses - Belgium Wallonia
Sossey Alaoui, Khadija ULg; Rosillon, Francis ULg

in International Journal of Water Sciences (2013), 2(3), 1-11

In the present paper we investigated macrophyte community structure in 60 natural and impacted stream and river sites distributed throughout the Walloon river network. The objectives were to describe the ... [more ▼]

In the present paper we investigated macrophyte community structure in 60 natural and impacted stream and river sites distributed throughout the Walloon river network. The objectives were to describe the distribution of macrophyte assemblages in relation to physico‐chemical parameters of their environment and to assess the variability in ecological metrics within these watercourses. Two‐way clustering allowed us to simultaneously assign sample units and species to groups by performing two separate cluster analyses. Indicator species analysis allowed us to assess the degree to which a species indicated a group, based on its constancy and distribution of abundance. Six end‐groups were identified as a result of using twoway clustering and indicator species analysis techniques. Hygroamblystegium fluviatile, Chiloscyphus polyanthos and Lemanea fluviatilis were found to characterize acidic and low impacted streams and rivers (G1), while Ranunculus fluitans was found in all low impacted large streams (G2). Potamogeton pectinatus, proved to be more common in eutrophicated waters in the calcareous areas particularly in the ʺLoess low plateauxʺ region (G6). Cinclidotus riparius, Fissidens crassipes and Pellia endiviifolia, appeared in rivers situated in the Condroz region (G4), which was characterized by a high concentration of nitrogen. [less ▲]

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