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Quantification of Strain of the Pan-African in Mvog-Betsi Area (Yaoundé Group, Cameroon)
Jean Engelbert Mpesse,
Joseph Martial Akame,
Eric José Messi Ottou,
Bernard Njom,
Sébastien Owona,
Jean Bosco Olinga,
Justin Lissom,
Joseph Mvondo Ondoa
Issue:
Volume 6, Issue 2, April 2018
Pages:
40-46
Received:
30 March 2018
Accepted:
24 April 2018
Published:
25 May 2018
Abstract: The ductile deformation in the paragneissic bed of Mvog-Betsi in the north-eastern part of Yaounde (Cameroon) appears to be intensive and may be traduced by a high shear rate (more than 10%). Some marker subjects that may quantify this strain are observed. Those are elliptical quartz and feldspar, and folds. The study of elliptical markers shows their preferential orientation. The initial rate Ri of the markers before the strain approaches 3.76, and the harmonic value of Rf is between 1.51 and 1.71. Main orientation Øf of strain’s ellipse from the direction of stretching in actual position is situated between -10 and -19. The strain’s rate RS is comprised between 1.1 and 1.7. The orientation ØS of the strain’s ellipse is situated between N10E and N20E. The rate of shortening varies between 20% and 75%.
Abstract: The ductile deformation in the paragneissic bed of Mvog-Betsi in the north-eastern part of Yaounde (Cameroon) appears to be intensive and may be traduced by a high shear rate (more than 10%). Some marker subjects that may quantify this strain are observed. Those are elliptical quartz and feldspar, and folds. The study of elliptical markers shows th...
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Scuds (Gammaridae) and Darters (Percidae) Dominate Aquatic Communities in a Stream Exhibiting Levels of Specific Conductance Exceeding 4,000 µS/cm
William Griffiths Kimmel,
David Gordon Argent
Issue:
Volume 6, Issue 2, April 2018
Pages:
47-52
Received:
23 April 2018
Accepted:
8 May 2018
Published:
28 May 2018
Abstract: Surface and underground extraction of coal has degraded many landscapes throughout the Appalachian region of the United States. The deleterious effects on steam biota of untreated acidic drainages high in heavy metals from active and abandoned sites have been well-documented. Mitigation strategies frequently include the addition of strong neutralizing agents in order to elevate pH and precipitate toxic metals. The resulting effluents exhibit high concentrations of sulfates, chlorides, carbonates, and other ions which can markedly raise the specific conductance of receiving streams. However, the impacts of such inputs on stream ecosystems are not well-studied. This study documents one such case, Whiteley Creek, a Monongahela River tributary in southwestern Pennsylvania, which receives treated effluents producing in-stream conductivity values in excess of 4,000 µS/cm. Fish and macroinvertebrate communities were sampled at ten sites from its headwaters to its Monongahela River confluence exhibiting conductivity values ranging from 2,400 – 5,400 µS/cm. Specific conductance showed no relationship to taxonomic richness of either community; however fish abundance declined with increasing conductivity, while macroinvertebrates increased. Extant communities dominated by tolerant taxa resulted in low macroinvertebrate and fish Indices of Biotic Integrity scores indicative of community stress. This study underscores the importance of biomonitoring and bioassessment of streams receiving effluents of chemically-treated acid mine drainages.
Abstract: Surface and underground extraction of coal has degraded many landscapes throughout the Appalachian region of the United States. The deleterious effects on steam biota of untreated acidic drainages high in heavy metals from active and abandoned sites have been well-documented. Mitigation strategies frequently include the addition of strong neutraliz...
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Heavy Metal Sensor Research Based on Microbial Fuel Cell
Yining Wu,
Ya Gao,
Ling Wang,
Hong Qi
Issue:
Volume 6, Issue 2, April 2018
Pages:
53-64
Received:
19 June 2018
Published:
20 June 2018
Abstract: In this study, a single chamber microbial fuel cell (MFC) was developed for heavy metal (copper ions) sensor with different concentrations at cathode, and its electrochemical activities in batch-mode operation including polarization curve, power density, anode potential, cathode potential and 30 minutes real-time voltage were characterized and studied. Under the condition of 1000 Ω external resistance, 100 mM PBS buffer and 1000 mg/L COD, results indicated that the real-time voltage of 30 min collected by the data acquisition was linearly developed with the change of concentration gradient, and the polarization curve showed that copper ion concentration and power density reflect a trend of X squared. In addition, the anode and cathode potential collected by the multimeter, also showed a trend of X2. By studying the relationship between electrochemical parameters and heavy metal ion concentration, a reliable correlation could be established to help us to use the detected electrochemical parameters to estimate the concentration of heavy metal ions in the environment of sewage pollution, so as to provide theoretical support for the development of new heavy metal sensors. The results provided new ideas for the practical application of microbial fuel cells.
Abstract: In this study, a single chamber microbial fuel cell (MFC) was developed for heavy metal (copper ions) sensor with different concentrations at cathode, and its electrochemical activities in batch-mode operation including polarization curve, power density, anode potential, cathode potential and 30 minutes real-time voltage were characterized and stud...
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Toxicity of Essential Oils to Stored Product Pest and Application to Extrusion Coating Film for Extend Rice Storage Life
Udomporn Pangnakorn,
Sombat Chuenchooklin
Issue:
Volume 6, Issue 2, April 2018
Pages:
65-70
Received:
19 June 2018
Published:
20 June 2018
Abstract: The toxicity of essential oils and wood vinegar was tested on stored-product insects that infest rice. The essential oils from 5 plants, lemon grass Cymbopogon citratus Stapf, citronella grass Cymbopogon nardus Linn, pomelo peel Citrus maxima (Burm) Merr, eucalyptus Eucalyptus globulus Labill, and kaffir lime peel Citrus hystrix, were extracted by stream distillation. Raw wood vinegar was purified by filtering. Toxicity to red flour beetle Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) was evaluated under laboratory conditions using topical application method (contact toxicity) and residual exposure method (fumigant toxicity). Overall, exposure to residual volatiles achieved higher mortality than droplet application. Kaffir lime peel achieved the highest mortality; 60% by topical application and 100% by residual exposure. A lower toxicity was found for lemon grass, citronella grass, eucalyptus and wood vinegar. Thereafter, kaffir lime peel oil extrusion coated onto plastic film that was used for storing packaged rice. Rice was stored in the bags for one month and pest infestations were quantified. The treatments showed no infestation of red flour beetle T. castaneum Herbst. Additional, the treatments showed significant protection against the 2 other stored product insects, including saw-toothed grain beetle, Oryzaephilus surinamensis L and rice weevil Sitophilus oryzae Linn. The results suggest that kaffir lime oil may be useful as a grain protectant against rice-infesting insects when used as a coating for bags made of extrusion film.
Abstract: The toxicity of essential oils and wood vinegar was tested on stored-product insects that infest rice. The essential oils from 5 plants, lemon grass Cymbopogon citratus Stapf, citronella grass Cymbopogon nardus Linn, pomelo peel Citrus maxima (Burm) Merr, eucalyptus Eucalyptus globulus Labill, and kaffir lime peel Citrus hystrix, were extracted by ...
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