50 research outputs found
About the use of Strychnos usambarensis GILG in Central Africa as curarizing arrow-poison
No full textpeer reviewedDuring a collecting trip of some medicinal and poisonous plants in Eastern Rwanda, the author observed the use of a hunting poison prepared from Strychnos usambarensis by Banyambo (small tribe living along Akagera river on the border between Rwanda and Tanzania). He could get the raw poison and arrows from these people. The author has shown the presence of curarizing properties caused by quaternary alkaloids located in barks of Strychnos usambarensis roots. This is an entirely new fact which allows us to assure the existence of a curare in Africa. Indeed BISSET and LEEUWENBERG ( Lloydia, 1968,31, p208-222) reviewed Strychnos sp. used in central Africa as ordeal and arrow poisons and they did not report the use by the natives of a curarizing arrow-poison
Critical Coupling and Synchronized Clusters in Arbitrary Networks of Kuramoto Oscillators
No full textabstract: The Kuramoto model is an archetypal model for studying synchronization in groups
of nonidentical oscillators where oscillators are imbued with their own frequency and
coupled with other oscillators though a network of interactions. As the coupling
strength increases, there is a bifurcation to complete synchronization where all oscillators
move with the same frequency and show a collective rhythm. Kuramoto-like
dynamics are considered a relevant model for instabilities of the AC-power grid which
operates in synchrony under standard conditions but exhibits, in a state of failure,
segmentation of the grid into desynchronized clusters.
In this dissertation the minimum coupling strength required to ensure total frequency
synchronization in a Kuramoto system, called the critical coupling, is investigated.
For coupling strength below the critical coupling, clusters of oscillators form
where oscillators within a cluster are on average oscillating with the same long-term
frequency. A unified order parameter based approach is developed to create approximations
of the critical coupling. Some of the new approximations provide strict lower
bounds for the critical coupling. In addition, these approximations allow for predictions
of the partially synchronized clusters that emerge in the bifurcation from the
synchronized state.
Merging the order parameter approach with graph theoretical concepts leads to a
characterization of this bifurcation as a weighted graph partitioning problem on an
arbitrary networks which then leads to an optimization problem that can efficiently
estimate the partially synchronized clusters. Numerical experiments on random Kuramoto
systems show the high accuracy of these methods. An interpretation of the
methods in the context of power systems is provided.Dissertation/ThesisDoctoral Dissertation Applied Mathematics 201
Nine 2-(2-Phenylethyl)chromone Derivatives from the Resinous Wood of Aquilaria sinensis and Their Inhibition of LPS-Induced NO Production in RAW 264.7 Cells
No full textA phytochemical investigation of aquilariae lignum resinatum, the resinous wood of Aquilaria sinensis (Lour.) Gilg, led to the isolation of nine new 2-(2-phenylethyl)chromone derivatives, aquilarones AI (19), together with two known analogues (10 and 11). Their structures were elucidated by extensive spectroscopic analyses, including UV, IR, NMR, and electronic circular dichroism (ECD) data, as well as by chemical methods. The absolute configuration of aquilarone A (1) was confirmed by single-crystal X-ray diffraction analysis of its acetonide derivative 1a. All the compounds exhibited significant inhibition of the nitric oxide production in RAW 264.7 cells, with IC50 values in the range of 5.1222.26 mu M. In addition, an HPLCUV comparison analysis of the resinous wood and resin-free wood is also included.Chemistry, OrganicSCI(E)10ARTICLE275389-539
Estimating the environmental impact of home energy visits and extent of behaviour change
No full textThe objective of this study was to estimate the environmental impact of a home energy visit programme, known as RE:NEW, that was delivered in London, in the United Kingdom. These home energy visits intended to encourage reductions in household carbon emissions and water consumption through the installation of small energy saving measures (such as radiator panels, in-home energy displays and low-flow shower heads), further significant energy saving measures (loft and cavity wall insulation) and behaviour change advice. The environmental impact of the programme was estimated in terms of carbon emissions abated and on average, for each household in the study, a visit led to an average carbon abatement of 146 kgCO2. The majority of this was achieved through the installation of small energy saving measures. The impact of the visits on the installation of significant measures was negligible, as was the impact on behaviour change. Therefore, these visits did not overcome the barriers required to generate behaviour change or the barriers to the installation of more significant energy saving measures. Given this, a number of recommendations are proposed in this paper, which could increase the efficacy of these home energy visits
Five new benzophenone glycosides from the leaves of Aquilaria sinensis (Lour.) Gilg
No full textPhytochemical investigation on the ethanol extract from the leaves of Aquilaria sinensis led to the isolation of five new benzophenone glycosides, aquilarinensides A-E (1-5). Their structures were elucidated by a combination of 1D and 2D NMR, HRMS, and chemical analysis. (C) 2014 Peng-Fei Tu. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.Chemistry, MultidisciplinarySCI(E)中国科技核心期刊(ISTIC)中国科学引文数据库(CSCD)0121573-15762
Bio-assay guided isolation and identification of alpha-glucosidase inhibitors from the leaves of Aquilaria sinensis
No full textEight alpha-glucosidase inhibitors including four new compounds were isolated from the 70% aqueous ethanolic extract of leaves of Aquilaria sinensis (Lour.) Gilg by activity-directed fractionation and purification processes. The ethanolic extract was first separated into petroleum ether, ethyl acetate, n-butanol and water soluble fractions and screened for inhibitory activity against alpha-glucosidase. Further activity-directed investigation lead to the isolation of four new compounds with moderate inhibitory activity, viz, aquilarisinin (1), aquilarisin (2), hypolaetin 5-O-beta-D-glucuronopyranoside (3) and aquilarixanthone (4) from the n-butanol fraction, and four known compounds showing potent activity including mangiferin (5), iriflophenone 2-O-alpha-L-rhamnopyranoside (6), iriflophenone 3-C-beta-D-glucoside (7) and iriflophenone 3,5-C-beta-D-diglucopyranoside (8) from the most potent ethyl acetate fraction. The structures of these compounds were determined by extensive spectroscopic analyses, including IR. UV, ESIMS, HRESIMS, 1D and 2D NMR. (C) 2011 Published by Elsevier Ltd.Biochemistry & Molecular BiologyPlant SciencesSCI(E)PubMed41ARTICLE2-3242-2477
Spatial linkages between decapod planktonic and benthic adult stages in a Newfoundland fjordic system
No full textThe relative importance of predatory decapod crustaceans in sedimentary communities depends on the spatial variability in their abundance and composition. At the scale of a fjord, such spatial patterns could be related to sill-mediated larval supply. This study examines larval and adult distributions of abundant predatory decapods at six representative sites in a sub-arctic Newfoundland fjord during three consecutive summers. Adult snow crab (Chionoecetes opilio) and toad crab (Hyas coarctatus, H. araneus) characterized outer areas of the fjord, whereas pandalid shrimp (Pandalus montagui) dominated inner areas, and rock crab (Cancer irroratus) showed only minor spatial differences. Multivariate analysis and nonparametric comparisons of larval abundance and composition suggest that the sill separating inner and outer areas of the fjord results in differences in larval supply that correspond to adult abundances for at least two of the species analyzed here: snow crab and pandalid shrimp. Although larval abundance was not related to adult distribution when all zoeal stages were considered, correspondence between larval and adult patterns emerged when only late stages (zoeae >= II) were included in the multivariate analyses. Nonparametric comparisons supported these results, indicating significant differences in larval abundance inside and outside the sill for corresponding species and stages. Our results suggest that larval supply may play a critical role in establishing adult spatial patterns at the scale of the entire fjord for some species, but a less relevant role at the finer scale represented by the sites and habitats located at each side of the sill.PT: J; CR: ASTHORSSON OS, 1991, J PLANK RES, V13, P91 BERGSTROM BI, 1991, SARSIA, V76, P133 BROOKINS KG, 1985, ESTUARIES, V8, P60 BUTMAN CA, 1989, J EXP MAR BIOL ECOL, V134, P37 CHRISTY JH, 1998, MAR ECOL-PROG SER, V174, P51 CLARK ME, 1999, MAR ECOL-PROG SER, V178, P69 COMEAU M, 1991, 1817 FISH AQ SCI CONAN GY, 1996, HIGH LATITUDE CRABS, P59 CONAN GY, 2002, LIFE HIST FISHERY MA CONNOLLY SR, 1998, AM NAT, V151, P311 COREY S, 1981, CRUSTACEANA, V41, P21 DAVIDSON KG, 1991, 1762 FISH AQ SCI DAVIS JLD, 2003, J EXP MAR BIOL ECOL, V293, P23 DIBACCO C, 2000, LIMNOL OCEANOGR, V45, P871 EGGLESTON DB, 1995, ECOL MONOGR, V65, P193 EGGLESTON DB, 1998, J EXP MAR BIOL ECOL, V223, P111 EPIFANIO CE, 2001, ESTUAR COAST SHELF S, V52, P51 ETHERINGTON LL, 2000, MAR ECOL-PROG SER, V204, P179 FELDER DL, 1985, CRUSTACEAN ISS, V2, P163 GABRIEL KR, 1971, BIOMETRIKA, V58, P453 GAGNON M, 1983, J PLANKTON RES, V5, P289 GAINES SD, 1992, NATURE, V360, P579 GARLAND ED, 2002, LIMNOL OCEANOGR, V47, P803 GILBERT D, 1993, 122 HYDR OC SCI GILG MR, 2003, ECOLOGY, V84, P2989 GRABE SA, 2003, J PLANKTON RES, V25, P417 GRASSLE JF, 1976, OECOLOGIA, V25, P13 HAYNES EB, 1981, FISH B US, V79, P421 HAYNES EB, 1985, FISH B-NOAA, V83, P253 HOBBS RC, 1992, MAR BIOL, V112, P417 HOLTE B, 1998, POLAR BIOL, V19, P375 HOOPER RG, 1975, BONNE BAY MARINE RES HOOPER RG, 1986, CRUSTACEANA, V50, P257 HUDON C, 1993, CAN J FISH AQUAT SCI, V50, P1422 JOHNS DM, 1981, MAR ECOL-PROG SER, V5, P75 LANTEIGNE M, 1985, THESIS U MONCTON MON LARSEN LH, 1997, HYDROBIOLOGIA, V355, P101 LAZZARI MA, 2002, ESTUARIES, V5, P1210 LENIHAN HS, 2001, MARINE COMMUNITY ECO, P253 LEWIS AG, 1986, J PLANKTON RES, V8, P1079 LIPCIUS RN, 1997, MAR FRESHWATER RES, V48, P807 LOCKE A, 1988, J PLANKTON RES, V10, P185 LOCKE A, 2002, 2606 FISH AQ SCI LOVRICH GA, 1997, J EXP MAR BIOL ECOL, V211, P225 MA HG, 2004, J MAR RES, V62, P837 MELVILLESMITH R, 1981, S AFR J ZOOL, V16, P10 MENGE BA, 2000, ECOL MONOGR, V70, P265 MEYERHARMS B, 1993, NETH J SEA RES, V31, P153 MOKNESS PO, 2001, MAR ECOL-PROG SER, V209, P257 MOKNESS PO, 2003, MAR ECOL-PROG SER, V250, P215 MOLONEY CL, 1994, MAR ECOL-PROG SER, V113, P61 MORGAN SG, 2001, MARINE COMMUNITY ECO, P159 OLMI EJ, 1991, J EXP MAR BIOL ECOL, V151, P169 OUELLET P, 1996, 2019 FISH AQ SCI PALMA AT, 1999, J EXP MAR BIOL ECOL, V241, P107 PAULA J, 2001, MAR ECOL-PROG SER, V215, P251 QUIJON PA, 2005, IN PRESS OECOLOGIA QUIJON PA, 2005, POLAR BIOL, V28, P495 ROBICHAUD DA, 1989, J SHELLFISH RES, V8, P13 ROBINSON M, 2000, MAR ECOL-PROG SER, V194, P133 ROBLES CD, 1997, ECOLOGY, V78, P1400 ROEGNER C, 2003, ESTUARIES, V26, P1058 ROFF JC, 1984, 1322 FISH AQ SCI SAINTEMARIE B, 1995, CAN J FISH AQUAT SCI, V52, P903 SANDIFER PA, 1975, ESTUARINE COASTAL MA, V3, P269 SKOLD M, 2003, MAR ECOL-PROG SER, V250, P163 SNELGROVE PVR, 1999, LIMNOL OCEANOGR, V44, P1341 SQUIRES HJ, 1993, J NW ATLANTIC FISHER, V15, P1 SQUIRES HJ, 1996, 2359 FISH AQ SCI SQUIRES HJ, 1996, NAFO SCI COUNCIL STU, V33, P1 SQUIRES HJ, 2000, J NW ATL FISH SCI, V18, P43 STARR M, 1994, J PLANKTON RES, V16, P1137 THRUSH SE, 1999, AUST J ECOL, V24, P344 TODD CD, 1998, HYDROBIOLOGIA, V375, P1 TODD CD, 2003, J EXP MAR BIOL ECOL, V290, P247 TRUEBLOOD DD, 1994, LIMNOL OCEANOGR, V39, P1440 UNDERWOOD AJ, 1989, TRENDS ECOL EVOL, V4, P16 WAINWRIGHT TC, 1993, J CRUSTACEAN BIOL, V13, P36 WEHRTMANN IS, 1994, ESTUARIES, V17, P509 WIECZOREK SK, 1995, J CRUSTACEAN BIOL, V15, P236 YUND PO, 1991, LIMNOL OCEANOGR, V36, P1167 ZAR JH, 1974, BIOSTATISTICAL ANAL; NR: 82; TC: 0; J9: J MAR RES; PG: 22; GA: 956TOSource type: Electronic(1
Eruptive shearing of tube pumice: Pure and simple
No full text© Author(s) 2016. Understanding the physicochemical conditions extant and mechanisms operative during explosive volcanism is essential for reliable forecasting and mitigation of volcanic events. Rhyolitic pumices reflect highly vesiculated magma whose bubbles can serve as a strain indicator for inferring the state of stress operative immediately prior to eruptive fragmentation. Obtaining the full kinematic picture reflected in bubble population geometry has been extremely difficult, involving dissection of a small number of delicate samples. The advent of reliable high-resolution tomography has changed this situation radically. Here we demonstrate via the use of tomography how a statistically powerful picture of the shapes and connectivity of thousands of individual bubbles within a single sample of tube pumice emerges. The strain record of tube pumice is modelled using empirical models of bubble geometry and liquid rheology, reliant on a constraint of magmatic water concentration. FTIR analysis reveals an imbalance in water speciation, suggesting post-eruption hydration, further supported by hydrogen and oxygen isotope measurements. Our work demonstrates that the strain recorded in the tube pumice dominated by simple shear (not pure shear) in the late deformational history of vesicular magma before eruption. This constraint in turn implies that magma ascent is conditioned by a velocity gradient (across the conduit) at the point of origin of tube pumice. Magma ascent accompanied by simple shear should enhance high eruption rates inferred independently for these highly viscous systems
A monograph of the Anisophylleaceae (Cucurbitales) with description of 18 new species of Anisophyllea
No full textA monographic study of the family Anisophylleaceae in the order Cucurbitales was carried out. Four genera, Anisophyllea (67 spp.), Combretocarpus (1 sp.), Poga (1 sp.), and Polygonanthus (2 spp.), and together 71 species are recognized, of which 18 are described as new. The 18 new species are all in Anisophyllea and include A. bakoensis, A. biokoensis, A. borneensis, A. cuneata, A. dinghoui, A. glandibeccariana, A. glandulipetiolata, A. insularis, A. malayensis, A. myriostictoides, A. neopurpurascens, A. obanica, A. rengamensis, A. rubroglandula, A. sabahensis, A. sarawakensis, A. sessiliflora, and A. sumatrana. Keys to the genera and to species of Anisophyllea and to those of Polygonanthus are provided. All species are described in detail and all but two are illustrated. Information on their distribution and habitat, phenology, and vernacular name and local usage, if available, is given. Distribution map of every species is presented. Taxonomic history, taxonomic characters, and various taxonomic issues are discussed. We also lectotypify or neotypify 30 names in the family including Anisophyllea apetala Scortechini ex King, A. beccariana Baillon, A. boehmii Engler, A. brachystila Engler & von Brehmer, A. buettneri Engler, A. cabole Henriques, A. cordata Engler & von Brehmer, A. curtisii King, A. exellii P. A. Duvigneaud & Dewit, A. fissipetala Engler & von Brehmer, A. fruticulosa Engler & Gilg, A. gaudichaudiana Baillon, A. gossweileri Engler & Brehmer, A. griffithii Oliver, A. guianensis Sandwith, A. mayumbensis Exell, A. meniaudi Aubreville & Pellegrin, A. obtusifolia Engler & Brehmer, A. poggei Engler ex De Wildeman & T. Durand, A. pomifera Engler & Brehmer, A. purpurascens Hutchinson & Dalziel, A. scortechinii King, A. sororia Pierre, A. strychnoides Engler & Brehmer, A. tomentosa Rolfe, A. trapezoidalis Baillon, A. zeylanica Bentham, Combretocarpus motleyi J. D. Hooker, Macrosolen rotundatus Miquel, and Poga oleosa Pierre
Biological activity of folkloric plants used in the treatment of ‘u wela’ against pathogens
No full textDATA AVAILABILITY :
The data used to support the findings of this study may be
released upon application to the corresponding author,
S.M.M.This article is partially based on the
author’s PhD thesis at the University of Limpopo, South
Africa.BACKGROUND : ‘U wela’ also known as ‘Divhu’ in ‘Tshivenda’ is a sexually transmitted infection caused by a combination of fungal and bacterial microorganisms that affects males because of unprotected sexual encounters with a woman who has had an abortion or miscarriage.
AIM : The study aimed to investigate medicinal plants used to treat ‘u wela’ and determine their biological activity against Neisseria gonorrhoeae and Candida albicans.
SETTING : Eight plant species (Elaeodendron transvaalense [Burtt Davy] R.H. Archer, Albizia versicolor Welw. ex Oliv, Xanthocercis zambesiaca Baker, Cassia abbreviata subsp. beareana [Holmes] Brenan, Anthocleista grandiflora Gilg, Myrothamnus flabellifolius Welw., Mimusops zeyheri Sond, and Capparis tomentosa Lam.) used to combat ‘u wela’ were selected from the Ethnomedicinal plant’s database of over 300 medicinal plants used for medicinal purposes in humans, in the Vhembe district, Limpopo province, South Africa.
METHODS : The antimicrobial activity of the plant extracts was investigated against Candida albicans and Neisseria gonorrhoeae using serial dilution and bioautography assays.
RESULTS : The plant extracts of A. versicolor and C. abbreviata had excellent activity with a low minimum inhibitory concentration (MIC). value of 0.02 and 0.07 mg/mL, respectively. In bioautograms developed in benzene/ethanol/ammonia hydroxide (BEA), active compounds were visible in the extracts of A. versicolor.
CONCLUSION : A. versicolor had excellent antimicrobial activity and may be used in traditional therapy to combat ‘u wela’.
CONTRIBUTION : The study has demonstrated that A. versicolor is a promising plant species that could lead to the discovery of novel drugs to combat ‘u wela’.The National Research Foundation
(NRF).http://www.jomped.org/hj2024Paraclinical SciencesSDG-03:Good heatlh and well-bein
