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Phytochemical analyses, antimicrobial and antioxidant activities of stem bark extracts of Distemonanthus benthamianus H. Baill. and fruit extracts of Solanum torvum Sw. from Gabon

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Asian Pacific Journal of Tropical Biomedicine 2019年第5期9卷 209-216页

作者： Cédric Sima Obiang rick Léonid Ngoua Meye Misso Guy Roger Ndong Atome Joseph Privat Ondo Louis Clément Obame Engonga Edouard Nsi Emvo Laboratory of Research in Biochemistry University of Sciences and Technology of Masuku Laboratory of Natural Substances and Organometallic Synthesis University of Sciences and Technology of Masuku

Objective: To evaluate the phytochemical constituents, antimicrobial and antioxidant activities of the extracts of Distemonanthus benthamianus(D. benthamianus) stem bark and Solanum torvum(S. torvum) fruit which have been used as traditional medicinal herbs in Gabon. Methods: Plant extracts were subjected to a qualitative study(phytochemical screening) and a quantitative(dosing) study of secondary metabolites. Antioxidant activity was tested by 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid assay. Bacteria and fungi susceptibility tests were performed on Mueller Hinton medium and solid Sabouraud, respectively, using the diffusion method, while minimum inhibitory concentration, minimum fungicidal concentration and minimum bactericidal concentration were evaluated by microdilution ***: The total phenol and tannin contents were significantly higher in the water-ethanol extract compared to the other extracts of D. benthamianus and S. torvum. The water-ethanol and water-acetone extracts showed significantly higher antioxidant activity than the aqueous extracts of the two medicinal plants. However, the extracts presented weak antioxidant activities compared to standards(Vitamin C, BHA). The water-acetone and water-ethanol extracts of S. torvum showed the highest antimicrobial activity against Bacillus cereus LMG 13569 BHI, Shigella dysenteriae 5451 CIP, Shigella dysenteriae and Neisseria gonorrhoeae. Conclusions: Our results show that D. benthamianus and S. torvum can be promising sources of natural products with potential antimicrobial and antioxidant activities.

关键词： Antioxidants Phytochemical Antimicrobial Distemonanthus benthamianus Solanum torvum

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World Journal of Ophthalmology 2014年第4期4卷 130-139页

作者： rick N Nordgren Ahmed M Elkeeb Bernard F Godley Department of Ophthalmology and Visual Sciences University of Texas Medical BranchGalvestonTX 77555United States

Age-related macular degeneration(AMD) is the leading cause of irreversible blindness in the developed world. The quality of life of both patients and families is impacted by this prevalent disease. Previously, macular degeneration had no known effective treatment. Today, vitamins for non-exudative AMD and intravitreal injection of medications for its exudative form are primary forms of current treatment. Modern advances in molecular science give rise to new possibilities of disease management. In the year 2003 the sequencing of the entire human genome was completed. Since that time, genes such as complement factor H, high-temperature requirement factor A1, and age-relateed maculopathy susceptibility 2 have been discovered and associated with a higher risk of AMD. A patient's genetic make-up may dictate the effectiveness of current or future therapeutic options. In addition, utilizing genetic data and incorporating it into new treatments(such as viral vectors) may lead to longer-lasting(or permanent) VEGF blockade and specific targeting of complement related genes. There have also been considerable advances in stem cell directed treatment of AMD. Retinal pigment epithelial(RPE) cells can be derived from human embryonic stem cells, induced pluripotent stem cells, or adult human RPE stem cells. Utilizing animal models of RPE and retinal degeneration, stem cell-derived RPE cells have been successfully implanted into the subretinal space. They have been injected as a cell mass or as a pre-prepared monolayer on a thin membrane. Visual recovery has been demonstrated in a retinal dystrophic rat model. Preliminary data on 2 human subjects also demonstrates possible early visual benefit from transplantation of stem cell-derived RPE. As more data is published, and as differentiation and implantation techniques are optimized, the stabilization and possible improvement of vision in individuals with non-exudative macular becomes a real possibility. We conclude that the technologi

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Assessment of Pseudorange Multipath at Continuous GPS Stations in Mexico

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Positioning 2013年第3期4卷 253-265页

作者： G. Esteban Vázquez rick Bennett Joshua Spinler Department of Geosciences The University of Arizona Tucson USA. Faculty of the Earth and Space Sciences The Autonomous University of Sinaloa Culiacan Mexico

We conducted a study to quantify the amount of pseudorange multipath at continuous Global Positioning System (CGPS) stations in the Mexican territory. These CGPS stations serve as reference stations enabling rapid high-precision three-dimensional positioning capabilities, supporting a number of commercial and public safety applications. We studied CGPS data from a large number of publicly available networks spanning Mexico. These include the RGNA (National Active Geodetic Network) administered by INEGI (National Institute of Statistics and Geography), the PBO network (Plate Boundary Observatory) funded by the National Science Foundation (NSF) and operated by UNAVCO (University NAVstar Consortium), the Southern California Integrated GPS Network (SCIGN), which is a collaboration effort of the United States Geological Survey (USGS), Scripps Institution of Oceanography and the Jet Propulsion Laboratory (JPL), the UNAM network, operated by the National Seismological System (SSN) and the Institute of Geophysics of the National Autonomous University of Mexico (UNAM), the Suominet Geodetic Network (SNG) and the CORS (Continuously Operating Reference Station) network, operated by the Federal Aviation Administration (FAA). We evaluated a total of 53 CGPS stations, where dual-frequency geodetic-grade receivers collected GPS data continuously during the period from 1994 to 2012. Despite carefully selected locations, all GPS stations are, to some extent, affected by the presence of signal multipath. For GPS network users that rely on pseudorange observables, the existence of pseudorange multipath could be a critical source of error depending on the time scale of the application. Thus, to identify the most and the least affected GPS stations, we analyzed the averaged daily root mean square pseudorange multipath variations (MP1-RMS and MP2-RMS) for all feasible satellites tracked by the CGPS networks. We investigated the sources of multipath, including changes associated with hard

关键词： Pseudorange Multipath GPS Network

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Ice Jam Modelling of the Lower Red River

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Journal of Water Resource and Protection 2012年第1期4卷 1-11页

作者： Karl-Erich Lindenschmidt Maurice Sydor rick Carson Robert Harrison 不详

The lower reach of the Red River between Winnipeg and Lake Winnipeg is very prone to ice jam flooding. The one- dimensional ice jam model RIVICE was implemented for this reach to better understand the processes leading to such events and to provide a tool to evaluate strategies for ice jam mitigation. The most downstream portion of this river stretch flows through a delta and marsh system which poses challenges in modelling ice jams in such an area of low-lying topography and river banks. Solutions to overcome these challenges are discussed in this paper and results of one such solution using water abstractions from the main channel are also presented. Abstractions are inserted in the model to represent under-ice leakage from the main channel to side channel storage and diversions (up to 65% in the Red River delta) and spillage into the delta floodplain.

关键词： Ice Jam Modeling Netley Creek Letley-Libau Marsh Red River Delta RIVICE

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Routing Protocols and Concepts : CCNA Exploration Companion Guide

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1000年

作者： rick Graziani Allan Johnson

Inside the router -- CLI configuration and addressing -- Building the routing table -- Path determination and switching functions.

ISBN: (纸本)9781587132728

Inside the router -- CLI configuration and addressing -- Building the routing table -- Path determination and switching functions.

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Evaluation of Airport Surface Surveillance Technologies

Evaluation of Airport Surface Surveillance Technologies

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1996 CIE International Conference of Radar(ICR’96)

作者： Alex Smith Carl Evers rick Cassell Rannoch Corporation 1800 Diagonal Rd.

＜正＞Continual increases in traffic volume,coupled with the pursuit for safer,more efficient Air Traffic Control （ATC）have driven up the requirements for airport surveillance *** previous years,ATC relied on sight,pilot position reports,and primary radar returns. However,with advances in other aircraft systems,such as navigation and the use of differential satellite navigation,aviation authorities are now looking to increase efficiency in the terminal area,while improving *** this paper we discuss the evolving requirements for airport surveillance systems and some of the technologies currently under evaluation for use at larger and medium sized *** describe the development and use of a relatively new concept,the Required System Performance（RSP）and its application to evaluation of airport surveillance requirements and systems.

关键词： Airports Surveillance Aircraft navigation Air traffic control Spaceborne radar Satellite navigation systems Air safety System performance Standards development Routing

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HAZARD MITIGATION OF THE IMPACT OF A PROGRESIVE TUNNEL COLLAPSE Paper No.114

HAZARD MITIGATION OF THE IMPACT OF A PROGRESIVE TUNNEL COLLA...

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ISRM-Sponsored International Symposium on Rock Mechanics:"Rock Characterisation,Modelling and Engineering Design Methods"(SINOROCK2009)

作者： Paul Beetham Robert Hutchison rick Lowe Opus International Consultants

The United Kingdom has a long legacy of mineral extraction *** the Nottingham area,these have primarily focused on coal *** local colliery,the 38 ha Gedling Colliery,is to be redeveloped to allow construction of new houses,leisure and retail facilities. Redevelopment of historical collieries pose a number of interesting challenges for today's Engineers ranging from colliery spoil to near surface historical mined *** challenge that is not encountered frequently is the impact of historical tunnels on future developments. The main access road to the new development,which is to be constructed on a 12m high embankment,traverses a historical railway *** question that was posed to the Engineer's was;will the construction of the new access road cause the tunnel to collapse? The ground conditions in the area comprise the Radcliffe Formation of the Mercia Mudstone Group overlying the Sneinton *** formations can be described as interlayered mudstone,siltstone and fine grained *** distinct sets of discontinuities are prevalent in the strata. In order to ascertain the risk of collapse,a number of intrusive and non intrusive investigations were *** nonintrusive investigations comprised:a visual inspection,a delamination survey,a ground probing radar survey from the ground surface and an electrical resistance tomography survey from within the tunnel *** investigations comprised rotary coring of the Mercia Mudstone and of the tunnel lining. Numerical modelling of the proposed development including it's construction sequences was undertaken.A number of discrete models were analysed including 2D boundary and finite element analysis and a 3D stability analysis of the tunnel itself. The findings of the investigation and analysis were that the tunnel 'bore' itself was generally stable but the tunnel lining was in a state of degradation with approximately 11%failed to *** led to the conclusion that far fr

关键词： Tunnel Embankment Finite Element Geotextile Hazard Numerical Mitigation

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The dynamics of color signals in male threespine sticklebacks Gasterosteus aculeatus

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Current Zoology 2016年第1期62卷 23-31页

作者： Meike HIERMES Ingolf P. rick Marion MEHLIS Theo C. M. BAKKER Institute for Evolutionary Biology and Ecology University of Bonn An der Immenburg 1 53121 Bonn Germany

Body coloration and color patterns are ubiquitous throughout the animal kingdom and vary be- tween and within species. Recent studies have dealt with individual dynamics of various aspects of coloration, as it is in many cases a flexible trait and changes in color expression may be context-de- pendent. During the reproductive phase, temporal changes of coloration in the visible spectral range （400-700 nm） have been shown for many animals but corresponding changes in the ultravio- let （UV） waveband （300-400 nm） have rarely been studied. Threespine stickleback Gasterosteus aculeatus males develop conspicuous orange-red breeding coloration combined with UV reflect- ance in the cheek region. We investigated dynamics of color patterns including UV throughout a male breeding cycle, as well as short-term changes in coloration in response to a computer- animated rival using reflectance spectrophotometry and visual modeling, to estimate how colors would be perceived by conspecifics. We found the orange-red component of coloration to vary during the breeding cycle with respect to hue （theta/R50） and intensity （achieved chroma/red chroma）. Furthermore, color intensity in the orange-red spectral part （achieved chroma） tended to be increased after the presentation of an artificial rival. Dynamic changes in specific measures of hue and intensity in the UV waveband were not found. In general, the orange-red component of the signal seems to be dynamic with respect to color intensity and hue. This accounts in particular for color changes during the breeding cycle, presumably to signal reproductive status, and with limitations as well in the intrasexual context, most likely to signal dominance or inferiority.

关键词： breeding season color change color signals stickleback structural coloration UV coloration

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全球最优秀的风险投资公司

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科学投资 2000年第12期 69-71,73-74,76,78,81-82页

作者： rick

当决定对风险投资公司进行排名时，我们意识到这并非易事。

关键词：风险投资公司排名全球决定最优优秀意识

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Ergot Alkaloid Effects on Bovine Sperm Motility <i>In Vitro</i>

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Advances in Reproductive Sciences 2019年第1期7卷 7-15页

作者： Ryan Page Toby Lester rick Rorie Charles Rosenkrans Jr. Department of Animal Science Division of Agriculture University of Arkansas System Fayetteville Arkansas USA

Cattle in some parts of the world graze pastures that consist of tall fescue that may contain ergot alkaloid contamination. Those ergot alkaloids are associated with reduced reproductive rates in cattle. Our objective was to determine if ergot alkaloids [dihydroergotamine (DHET), ergonovine (EN), and ergotamine (ET)] directly affect bovine sperm characteristics. Spermatozoa were collected from mature Angus (n = 2) and Balancer (n = 4) bulls. Within bull, treatments were structured as a 3 × 5 factorial with three alkaloids (DHET, EN, and ET) and five concentrations of each alkaloid (0, 33, 66, 100, or 200 μM). Spermatozoa (25 × 106) were incubated (39?C) in 1 mL of modified sperm medium. Sperm motility characteristics were evaluated using CASA (Hamiliton Thorne IVOS, Beverly, MA) at 0, 3, and 6 h after initial alkaloid exposure. Initial sperm motility was (69% ± 1.1%) and declined (P = 0.01) to (35% ± 2.6%) at 6 h. Sperm motility decreased (P P < 0.05) both characteristics. Our results demonstrate that ergot alkaloids (ET and DHET) can directly alter bovine sperm motility and morphology, which adds to our understanding of how ergot alkaloids may hinder cattle reproductive rates.

关键词： CASA Bull Spermatozoa Toxins

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