scholarly journals Au and Te Minerals in Seafloor Massive Sulphides from Semyenov-2 Hydrothermal Field, Mid-Atlantic Ridge

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 294 ◽  
Author(s):  
Anna Firstova ◽  
Tamara Stepanova ◽  
Anna Sukhanova ◽  
Georgy Cherkashov ◽  
Irina Poroshina
Keyword(s):  
Low Temperature ◽  
Mean Value ◽  
Hydrothermal Field ◽  
Additional Contribution ◽  
Core Complex ◽  
Mid Atlantic Ridge ◽  
The Mean ◽  
High Concentrations ◽  
Seafloor Massive Sulphides ◽  
Massive Sulphides

The Semyenov-2 hydrothermal field located at 13°31′N of the Mid-Atlantic Ridge (MAR) is associated with an oceanic core complex (OCC) and hosted by peridotites and basalts with minor amounts of gabbro and plagiogranites. Seafloor massive sulphides (SMS) are represented by chimneys with zonality, massive sulphides without zonality and sulphide breccia cemented by opal and aragonite. The mean value of Au (20.6 ppm) and Te (40 ppm) is much higher than average for the MAR SMS deposits (3.2 ppm and 8.0 ppm, respectively). Generally, these high concentrations reflect the presence of a wide diversity of Au and Te minerals associated with major mineral paragenesis: primary native gold, melonite (NiTe2) and tellurobismuthite (Bi2Te3) are related to high-temperature chalcopyrite (~350 °C); electrum (AuAg)1, hessite (Ag2Te) and altaite (PbTe) are related to medium- and low-temperature Zn-sulphide and opal assemblages (260–230 °C). Calaverite (AuTe2) and Te-rich “fahlore” Cu12(Sb,As,Te)4S13 are texturally related to the chalcopyrite-bornite-covellite. Enrichment of Au in sulphide breccia with opal and aragonite cement is driven by the re-deposition and the process of hydrothermal reworking of sulphide. The low-temperature fluid mobilizes gold from primary sulphide, along with Au and Te minerals. As a result, the secondary gold re-precipitate in cement of sulphide breccia. An additional contribution of Au enrichment is the presence of aragonite in the Cu-Zn breccia where the maximal Au content (188 ppm) is reached.

scholarly journals Geological fate of seafloor massive sulphides at the TAG hydrothermal field (Mid-Atlantic Ridge)

2019 ◽  
Vol 107 ◽  
pp. 903-925 ◽  
Author(s):  
Bramley J. Murton ◽  
Berit Lehrmann ◽  
Adeline M. Dutrieux ◽  
Sofia Martins ◽  
Alba Gil de la Iglesia ◽  
...  
Keyword(s):  
Hydrothermal Field ◽  
Mid Atlantic Ridge ◽  
Seafloor Massive Sulphides ◽  
Massive Sulphides ◽  
Tag Hydrothermal Field

Inorganic Bromide in Higher Fungi

1984 ◽  
Vol 39 (9-10) ◽  
pp. 863-866 ◽  
Author(s):  
T. Stijve
Keyword(s):  
Trace Element ◽  
Dry Weight ◽  
Mean Value ◽  
Inorganic Salts ◽  
Chromatographic Methods ◽  
The Mean ◽  
High Concentrations

Abstract A total of 138 samples of higher fungi, representing 35 species (15 belonging to the genus Amanita), were analysed for the trace element bromine using spectrophotometric and gas chromatographic methods. High concentrations of bromine, up to 100 mg/kg on dry weight, were encountered in Amanitaceae, especially in members of the subsections Phalloideae and Eu-Amanita, whereas in other fungi the mean value for this element was only 3,3 m g/kg. Some bromine-accumulating Amanitas also contained unusually high chlorine levels. Am axi­mum concentration of 3 percent on dry weight was measured in A. phalloides. It could be demonstrated that most, if not all of bromine and chlorine was present in the fungi as ionisable inorganic salts. Two organochlorine metabolites, previously reported in some mushrooms, were absent in A. phalloides and A. muscaria.

A pharmacokinetic study of Genetaxyl (G) together with cyclosporin A (CsA) administered orally in cancer patients

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 12002-12002
Author(s):  
C. Liau ◽  
E. Lepper ◽  
H. Wang ◽  
M. Yang ◽  
T. Chiou ◽  
...  
Keyword(s):  
Equilibrium Dialysis ◽  
Volume Of Distribution ◽  
Mean Value ◽  
Phase Ii Trials ◽  
Patients With Cancer ◽  
The Mean ◽  
High Concentrations ◽  
Apparent Bioavailability ◽  
Dose Levels ◽  
Dose Dependent

12002 Background: Oral administration of paclitaxel given with CsA has shown promising activity in Phase II trials, but the apparent bioavailability is low and dose-dependent due to the presence of high concentrations of Cremophor EL (CrEL). We hypothesized that the use of a novel oral paclitaxel formulation containing only 20% CrEL (Genetaxyl [G]; Genovate Biotechnology Ltd., Taiwan), given with CsA is associated with an improved pharmacokinetic (PK) profile. Methods: Cohorts of 6 patients with cancer were treated with oral G at a dose of 60, 120, or 180 mg/m2 and 10 mg/kg of oral CsA in cycle 1. In cycle 2, patients received IV G (175 mg/m2, 3-h infusion). Three additional patients received generic IV paclitaxel (GIP). Serial blood samples were analyzed by LC/MS/MS and equilibrium dialysis, to determine total and unbound paclitaxel PK. Results: The mean (± SD) total paclitaxel AUCs were 1299±189, 1682±636, and 2204±1407 ng.h/mL at the 3 consecutive dose levels, suggesting nonlinear PK. However, based on unbound AUC, the oral bioavailability was dose-independent (P=.62), with a mean value of 37.2±18.6% (n=15). As expected, the total paclitaxel AUC following IV G (9024±4648 ng·h/mL) was lower than that for IV GIP (13,732±3983 ng·h/mL), as a result of increased clearance (39.6 vs 18.3 L/h) and a larger volume of distribution (768 vs 268 L). Interestingly, the unbound paclitaxel AUC was similar between the two IV formulations (P=.25), as the ratio of unbound/total paclitaxel for G was 2.5 times higher than that for GIP (12.5 vs 4.9%). Toxicity profiles were mild, with only 2 patients experiencing ≥ Gr 3 myelosuppression following oral G at 180 mg/m2. Conclusions: The mean bioavailability of paclitaxel following oral Genetaxyl with CsA was about 37%, which is higher than that observed previously with paclitaxel (range, 21–31%). Further clinical exploration of oral Genetaxyl in taxane-sensitive diseases is warranted. [Table: see text]

scholarly journals Mining the Deep: A global assessment of biodiversity and research effort at deep-sea hydrothermal vents in relation to mining of seafloor massive sulphides

2019 ◽  
Author(s):  
Andrew Thaler ◽  
Diva Amon
Keyword(s):  
Deep Sea ◽  
Hydrothermal Vent ◽  
Hydrothermal Vents ◽  
Research Effort ◽  
Scientific Discovery ◽  
Precious Metals ◽  
Biogeographic Provinces ◽  
High Concentrations ◽  
Seafloor Massive Sulphides ◽  
Massive Sulphides

When the RV Knorr set sail for the Galapagos Rift in 1977, the scientists aboard expected to find deep-sea hydrothermal vents. What they did not expect to find was life—abundant and unlike anything ever seen before. Submersible dives revealed not only deep-sea hydrothermal vents but entire ecosystem surrounding them, including the towering bright red tubeworms that would become icons of the deep sea. This discovery was so unexpected that the ship carried no biological preservatives. These first specimens were fixed in vodka from the scientists’ private reserves.Since that first discovery, deep-sea hydrothermal vents have been found throughout the oceans. As more regions are explored, newly discovered vent fields present the potential for entirely species and ecosystems. Increasingly, however, it is not scientific discovery, but the financial value of vent fields, and the ores they contain, that is driving exploration in the deep sea. Over the last five decades, a new industry has emerged to explore the potential of mining Seafloor Massive Sulphides (deep-sea hydrothermal vents that contain high concentrations of rare and precious metals). Multiple enterprises are developing mining prospects that include both active and inactive deep-sea hydrothermal vent fields. In order to understand the impacts of exploitation at deep-sea hydrothermal vents, scientists and miners must establish environmental baselines. Biodiversity is frequently used as a proxy for resilience and as a metric for assessing biological baselines but, since research effort is not distributed equally across the oceans, biodiversity estimates in the deep sea are rarely comprehensive. Studies have predominantly focused on a few key biogeographic provinces, while other regions have only been sampled sparingly. Managers, regulators, and mining companies are working from incomplete data, with inferences about the consequences, as well as mitigation and remediation practices, often drawn from studies of few vent ecosystems that are often different from those in which the impacts are expected to occur. To better assess our current understanding of deep-sea hydrothermal vent biodiversity, we undertook a quantitative survey of the last 40 years of vent research. A stark north/south divide was detected, demonstrating that while research was disproportionately focused in the Northern Hemisphere, mining prospects were overwhelmingly positioned in the Southern Hemisphere. In addition, we provided a ranked assessment of biodiversity in eight major biogeographic provinces, identified knowledge gaps in the available deep-sea hydrothermal vent exploration literature, and assessed sampling completeness to provide further guidance to regulators, managers, and contractors as they develop comprehensive environmental baseline assessments.

Microbial CO2fixation and sulfur cycling associated with low-temperature emissions at the Lilliput hydrothermal field, southern Mid-Atlantic Ridge (9°S)

2007 ◽  
Vol 9 (5) ◽  
pp. 1186-1201 ◽  
Author(s):  
Mirjam Perner ◽  
Richard Seifert ◽  
Stefan Weber ◽  
Andrea Koschinsky ◽  
Katja Schmidt ◽  
...  
Keyword(s):  
Low Temperature ◽  
Hydrothermal Field ◽  
Sulfur Cycling ◽  
Mid Atlantic Ridge

scholarly journals https://www.kau.edu.sa/Files/320/Researches/60264_31074.pdf

2011 ◽  
Vol 22 (2) ◽  
pp. 185-201
Author(s):  
Mohammed Amin M. Sharaf Mohammed Amin M. Sharaf
Keyword(s):  
Water Quality ◽  
Major And Trace Elements ◽  
Mean Value ◽  
Mineral Dissolution ◽  
Total Hardness ◽  
Mineral Contents ◽  
Domestic Use ◽  
The Mean ◽  
Sedimentary Succession ◽  
High Concentrations

This study dealt with the hydrochemistry of As Suqah area, NE of Jeddah, Saudi Arabia. The study is based on the analyses of the major and trace elements of 16 water samples. The groundwater shows relatively high concentrations in their overall mineral contents and a high EC, TDS, and total hardness as CaCO3. Two groundwater types were identified in the As Suqah area: Na-Mg-Ca-Cl-SO4 and Na-Ca-Mg-Cl water types. Sodium adsorption ratio has a mean value of 14.39. The exchangeable sodium ratio has a mean value of 0.456 and a maximum value of 1.706. The average magnesium hazard was found to be about 49.97. The groundwater in As Suqah area was slightly supersaturated with respect to calcite and supersaturated with respect to dolomite. The mean saturation indices for these species are 1.21 and 2.60 respectively. The main hydrochemical processes responsible for the above discussed variation in water quality are recharge, ion-exchange and mineral dissolution. The water quality within the sedimentary succession was found to be of relatively higher salinity. Its use is restricted for domestic use only if adequately treated.

Deposition of copper in cattle and buffaloes edible tissues slaughtered in Assiut city, Egypt

2020 ◽  
Vol 1 (1) ◽  
pp. 11-15
Author(s):  
T.H. Youssef ◽  
Y.A. Hefnawy ◽  
H.A. Hassan
Keyword(s):  
Quality Control ◽  
Atomic Absorption ◽  
Copper Content ◽  
Mean Value ◽  
The Other ◽  
Copper Level ◽  
Edible Tissues ◽  
Wet Weight ◽  
The Mean ◽  
High Concentrations

A total of 168 samples of livers, kidneys and muscles (part of the diaphragm) were screened. The samples were subjected to preparation and for measurement the level of copper (Cu) by using Atomic Absorption/Flaming Emission Spectrophotometer. Buffaloes organs showed variations in their copper content. As for liver, the mean copper concentrations were 11.52 ± 5.41 with a range varied from 2.34 to 21.88 μg/g wet weight. Whereas in buffalo kidneys copper level varied from 2.34 to 15.13 with a mean value of 5.85 ± 4.34 μg/g wet weight. Moreover, the concentrations of copper in buffalo muscles varied from1.56 to 15.50 μg/g wet weight with a mean value of 4.35 ± 3.96. On the other hand, copper in cattle liver varied in its concentrations where the mean value was 11.59 ± 5.79, with a range varied from 3.13 to 25.00 μg/g wet weight. Copper in cattle kidneys varied from 2.50 to 16.3 with a mean value of 4.18 ± 3.12 μg/g wet weight. Besides, the concentrations of copper in cattle muscles were 3.23 ± 2.48, 1.88 and 14.34 μg/g wet weight, respectively as a mean, minimum and maximum. In conclusion, 1% - 26% of the examined samples of both cattle and buffalo were higher than the results obtained by Egyptian Organization Standardization and Quality Control (2008), in addition, livers samples have high concentrations of copper than kidneys and muscles.

Métabolisme périphérique de la testostérone en relation avec le cycle annuel de la testostérone et de la 5α-dihydrotestostérone plasmatiques chez le Blaireau européen (Meles meles L.) et le Renard roux (Vulpes vulpes L.)

1982 ◽  
Vol 60 (3) ◽  
pp. 406-416 ◽  
Author(s):  
D. Maurel ◽  
J. Boissin
Keyword(s):  
Annual Cycle ◽  
Meles Meles ◽  
Specific Protein ◽  
Mean Value ◽  
Breeding Period ◽  
Metabolic Clearance ◽  
Reproduction Period ◽  
The Mean ◽  
High Concentrations ◽  
Peripheral Metabolism

Seasonal variations in plasma contents of testosterone, 5α-dihydrotestosterone (5α-DHT) and other parameters related to the peripheral metabolism of testosterone have been determined in adult foxes and badgers, in natural climatic conditions.In both species, testosterone reaches peak levels in winter, but whereas the fox takes a sexual break beginning in spring (April), the badger has high concentrations of hormones until the summer. The mean annual concentration of testosterone is four times higher in the badger than in the fox; the annual mean value of 5α-dihydrotestosterone is identical in both species and levels of 5α-DHT are significantly higher during the breeding period.The annual cycle of testosterone peripheral metabolism in the fox is characterized by a decreased rate during summer and fall and an increased rate during winter (breeding period). In the badger, the metabolic clearance rate is high at the end of the fall and at the onset of the breeding period (October to January) and low during the peak reproduction period (February to April) and then increases as the period of sexual break approaches.The annual cycle of testosterone production rate is characterized in both species by a fall or prewinter increase; in the fox, this increase is followed by a decrease at the end of the winter, whereas the badger keeps pretty well the same rate of production until the summer.Seasonal variations of hormone peripheral metabolism are examined and discussed in relation to the fluctuations in testosterone levels and the hormone-specific protein linkage capacity.[Journal Translation]

scholarly journals SPATIAL DISTRIBUTION OF HEAVY METAL CONTAMINATION IN GROUNDWATER OF ONITSHA URBAN, SOUTHEAST NIGERIA

2021 ◽  
pp. 11-22
Author(s):  
E.I Okoyeh ◽  
V.C Ahaneku ◽  
A Utom ◽  
I.E Udegbunam ◽  
G.E Egwuonwu
Keyword(s):  
Heavy Metals ◽  
Spatial Distribution ◽  
Water Samples ◽  
Heavy Metal Contamination ◽  
Anthropogenic Impacts ◽  
Quality Standard ◽  
Mean Value ◽  
High Concentration ◽  
The Mean ◽  
High Concentrations

The investigation of the degree of trace heavy metals contamination in groundwater wells in Onitsha Southeast Nigeria, was carried out based on 20 preselected sample locations. The result of the analysis revealed water of relatively high acidity with pH ranging from 4.93 t0 6.94. The EC values for the analysed water samples ranged from 10.80 to 60.90u while TDS ranges from 20.00 to 410.00.Heavy metals in the form of Arsenic (As), Cadmium (Cd), Chromium (Cr), Iron (Fe), Nickel (Ni), Zinc (Zn), Vanadium (V) and Copper (Cu) were analyzed for their concentration in the water samples of the area. The study revealed that the mean value of Fe (0.832000 ± 1.0626228ppm) and Cd (0.043750 ± 0.0181713ppm) exceeded the permissible limit for NSDWQ water quality standard as indicated by the high concentrations of Fe and Cd values observed in water samples of the study area. The concentrations of the heavy metals except Fe and Cd range from Ni (0.000 – 0.750),(Cu 0.00 - 0.105), (Zn 0.00 – 1.798), (Cr 0.002 – 0.046), (As 0.000 – 0.056) and (Va 0.000 - 0.008). The spatial distribution of the heavy metals in the area shows that the eastern part of the study area has relative high concentration of the heavy metals which is attributed to anthropogenic impacts.

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