Integrating Core and Aeromagnetic Datasets to Evaluate Mineral Potential of Southern Nupe Basin, Nigeria

Aeromagnetic and core drilled data covering parts of southern Nupe Basin was acquired and interpreted with the view to evaluating the mineral potentials of the area through interpretation of the structural features in the area; determination of the curie isotherm depth; and correlation of aeromagnetic outcomes with the core sample data from the area. Two major regional fault trends were interpreted, trending, Northeast–Southwest (NE–SW) and NNE–SSW with minor northwest–southeast (NW–SE) directions. Two depth sources in the area are delineated namely; zone of shallow seated basement which ranges from 0.42km to 1.5km and zone of deeply seated basement which ranges from 1.91 to 3.50km.Results of qualitative interpretation of the Total magnetic intensity map (TMI) and Residual intensity map reveal that the magnetic intensities ranges from 7500 to 8460 nano-Telsa (nT) and -220 to 240 nT respectively. The depth to the centroid and top of the magnetic caustic bodies ranges from 9.00 to 17.10km and 0.4 to 3.10km respectively. Juxtaposing the topographical and core drilling data reveals that the oolitic iron ore level follows the topographical level which implies that the topography of the area controls the configuration of the iron ore deposit level. All these deduction are made considering the geology of the area.

Thickness record of varves from glacial Ojibway Lake recovered in sediment cores from Frederick House Lake, northeastern Ontario

The thicknesses of 384 rhythmic couplets were measured along a composite sequence of glacial Lake Ojibway glaciolacustrine deposits recovered in two sediment cores from Frederick House Lake, Ontario. The visual comparison of distinctive couplets in the CT-scan radiographs of the Frederick House core samples to photographs of core samples from Reid Lake show a match of ±1 varve number from v1656-v1902, and ±5 varve numbers between v1903-v2010, relative to the regional numbering of the Timiskaming varve series. There are two interpretations for the post-v2010 couplets that fall within the Connaught varve sequence of the regional series. In the first, the interpreted numbering spans from v2066-v2115, which produces a gap of 55 missing varves equivalent to v2011-v2065, and corresponds to the original interpretation of the Connaught varve numbering. The second spans v2011a-v2060a, and represents alternative (a) numbering for the same varves. Varve thickness data are listed in spreadsheet files (.xlsx and .csv formats), and CT-Scan radiograph images of core samples are laid out on a mosaic poster showing the interpreted varve numbering and between-core sample correlations of the varve couplets.

VOLN27B: A New Head-Tailed Halovirus Isolated from an Underground Salt Crystal and Infecting Halorubrum

A novel halovirus, VOLN27B, was isolated from a drill core sample taken at a depth of approximately 430 m, from a layer formed during the Cretaceous period (Anhui, China). VOLN27B infects the halophilic archaeon Halorubrum sp. LN27 and has a head-tailed morphotype with a contractile tail, typical of myoviruses. The average head diameter is 64 ± 2.0 nm, and uncontracted tails are 15 ± 1.0 × 65 ± 2.0 nm. The latent period is about 10 h. The maturing time of VOLN27B in cells of Halorubrum sp. LN27 was nearly 8 h. The adsorption time of VOLN27B on cells of Halorubrum sp. LN27 was less than 1 min. Virus particles are unstable at pH values less than 5 or when the NaCl concentration is below 12% ( w / v ). VOLN27B and Halorubrum sp. LN27 were recovered from the same hypersaline environment and provide a new virus-host system in haloarchaea.

Moisture Absorption Effects on the Mechanical Properties of Sandwich Biocomposites with Cork Core and Flax/PLA Face Sheets

The aim of this study was to evaluate the moisture absorption behaviour and its influence on the mechanical properties of newly developed sandwich biocomposites with flax fibre-reinforced poly-lactic acid (PLA) face sheets and soft cork as the core material. Three different types of sandwich biocomposite laminates comprised of different layup configurations, namely, non-woven flax/PLA (Sample A), non-woven flax/PLA and cork as core (Sample B) and non-woven flax/paper backing/PLA, cork as core (Sample C), were fabricated. In order to evaluate the influence of moisture ingress on the mechanical properties, the biocomposites were immersed in seawater for a period of 1200 h. The biocomposites (both dry and water immersed) were then subjected to tensile, flexural and low-velocity falling weight impact tests. It was observed from the experimental results that the moisture uptake significantly influenced the mechanical properties of the biocomposites. The presence of the cork and paper in sample C made it more susceptible to water absorption, reaching a value of 34.33%. The presence of cork in the core also has a considerable effect on the mechanical, as well as energy dissipation, behaviours. The results of sample A exhibited improved mechanical performance in both dry and wet conditions compared to samples B and C. Sample A exhibits 32.6% more tensile strength and 81.4% more flexural strength in dry conditions than that in sample C. The scanning electron microscopy (SEM) and X-ray micro-CT images revealed that the failure modes observed are a combination of matrix cracking, core crushing and face core debonding. The results from this study suggest that flax/PLA sandwich biocomposites can be used in various lightweight applications with improved environmental benefits.

Wood and bark water content and monthly stem growth in Amazonian tree species

ABSTRACT The knowledge of how trees respond to microclimate variability is important in the face of climate changes. The objectives of this study were to examine the variation in wood water content (WWC) and bark water content (BWC) in Amazonian trees, as well as to assess the effect of microclimatic variability on monthly diameter growth rates (DGR). We extracted a core sample from each of 120 trees (28 species) and determined WWC and BWC on a fresh matter basis. DGR was measured monthly during the 12 months of 2007. The effect of microclimatic variability on DGR was analyzed by redundancy analysis. Average BWC and WWC were 53.4% and 34.7%, respectively, with a large variation in stem water content among species (BWC = 36.2−67.1%; WWC = 26.4−50.8%). There was no significant relationship between stem diameter and WWC or BWC, nor between DGR and wood density (p > 0.05). However, wood density was negatively correlated with WWC (r s = −0.69, p < 0.001). The high BWC emphasizes the importance of the bark tissue in Amazonian trees. Contrary to expectations, variability of monthly irradiance, rainfall and temperature had no effect on DGR (p > 0.20). The unresponsiveness of DGR to microclimatic variability, even in an above-average rainy year such as 2007, indicates that other parts of the tree may have greater priority than the stem for carbon allocation during the dry season.

An Investigation on the Process of Reimbibition of Oil and Its Impact on Oil Recovery in the Yates Field

Summary In mixed- to oil-wet reservoirs characterized by intense natural fracturing where the dominant displacement mechanism is gravity drainage, surfactant injection can lead to a shift in wettability and incremental oil production. In some cases, oil can also reimbibe back into the rock matrix after the oil saturation has been reduced upon initial exposure to surfactant, suggesting limited permanence in the wettability shift. The reimbibition phenomenon is investigated in this paper using Amott cells. Three cationic surfactants (C12-, C12–16-, C16-based) with interfacial tensions (IFT) between 0.18 and 0.95 mN/m were preselected to be evaluated. Current application of the C12-based surfactant in the Yates field is considered successful based on incremental oil recovery seen during the treatment. Silurian dolomite (SD) rock samples were flooded with Yates crude oil before being aged at 60°C for 6 weeks. For the imbibition tests, the aqueous surfactant solution was set as the external phase within the Amott cell, and the recovery of oil was recorded periodically. After the imbibition tests ended, the rock samples were placed in an inverse Amott cell with the Yates oil as the external phase. Baseline tests were first conducted to show that without a surfactant in the oil or brine, no imbibition occurred. With a surfactant concentration of 3,000 ppm, oil recovery at the end of the imbibition tests varied from 34 to 60% of the original oil volume in the core sample. During the reimbibition test, a large amount of oil was able to reimbibe into the rock, displacing the brine. Most of the displacement occurred within the first 2 weeks. The net oil recovery, taken as the final volume of oil recovered in the imbibition test minus the final volume of oil reimbibed into the rock, ranged from 0 to 18%. Given the possibility of surfactant dilution in field applications, another set of tests was conducted with 1,500 ppm. A reduction in oil recovery during imbibition was observed for all the tested surfactants. Partition coefficients were determined for each of the tested surfactants, and the ion-pair mechanism was used to explain the net oil recovery results. Lastly, the impact of rock permeability on reimbibition was investigated. Results show increasing permeability may lead to a linear response in oil reimbibition; therefore, minimizing the permeability range when selecting rock samples may be necessary when conducting the reimbibition test. The importance of oil reimbibition is demonstrated in the experimental study, and we make an argument for conducting both the imbibition and reimbibition tests to better evaluate surfactant efficacy. The improved understanding of wettability alteration should lead to advancements in chemical enhanced oil recovery (EOR) designs for field treatments.

Visualization of radiocesium distribution in surface layer of seafloor around Fukushima Daiichi Nuclear Power Plant

Large quantities of volatile radionuclides were released into the atmosphere and the hydrosphere following the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on March, 2011. Monitoring of radiocesium in sediment is important for evaluating the behavior of radiocesium in the environment and its effect on aquatic organisms. In this study, the radiocesium distribution in the surface sediment around the FDNPP was visualized as a radiocesium concentration map using periodical survey data from a towed gamma-ray detection system. The uncertainty of the radiocesium map was evaluated via comparison with a large amount of sediment core sample data. The characteristics of the radiocesium distribution were examined considering the seafloor topography and a geological map, which were obtained via acoustic wave survey. The characteristics of the formation of 137Cs anomaly at the estuaries were analyzed using a contour map of 137Cs concentration combined with water depth. Validation of the created map showed that it was comparable with actual sediment core samples. The map generated using the towed radiation survey depicted the 137Cs concentration distribution as the position resolution of a 1 km mesh. Finally, the 137Cs concentration decreased with time in consideration of such uncertainty.