28 research outputs found
Sustainable seabed mining: guidelines and a new concept for Atlantis II Deep
The feasibility of exploiting seabed resources is subject to the engineering solutions, and economic prospects. Due to rising metal prices, predicted mineral scarcities and unequal allocations of resources in the world, vast research programmes on the exploration and exploitation of seabed minerals are presented in 1970s. Very few studies have been published after the 1980s, when predictions were not fulfilled. The attention grew back in the last decade with marine mineral mining being in research and commercial focus again and the first seabed mining license for massive sulphides being granted in Papua New Guinea’s Exclusive Economic Zone.Research on seabed exploitation and seabed mining is a complex transdisciplinary field that demands for further attention and development. Since the field links engineering, economics, environmental, legal and supply chain research, it demands for research from a systems point of view. This implies the application of a holistic sustainability framework of to analyse the feasibility of engineering systems. The research at hand aims to close this gap by developing such a framework and providing a review of seabed resources. Based on this review it identifies a significant potential for massive sulphides in inactive hydrothermal vents and sediments to solve global resource scarcities. The research aims to provide background on seabed exploitation and to apply a holistic systems engineering approach to develop general guidelines for sustainable seabed mining of polymetallic sulphides and a new concept and solutions for the Atlantis II Deep deposit in the Red Sea.The research methodology will start with acquiring a broader academic and industrial view on sustainable seabed mining through an online survey and expert interviews on seabed mining. In addition, the Nautilus Minerals case is reviewed for lessons learned and identification of challenges. Thereafter, a new concept for Atlantis II Deep is developed that based on a site specific assessment.The research undertaken in this study provides a new perspective regarding sustainable seabed mining. The main contributions of this research are the development of extensive guidelines for key issues in sustainable seabed mining as well as a new concept for seabed mining involving engineering systems, environmental risk mitigation, economic feasibility, logistics and legal aspects
Assessing the performance of a multi-nested ocean circulation model using satellite remote sensing and in situ observations
This study presents a multi-nested ocean circulation model developed recently for the central Scotian Shelf. The model consists of four submodels downscaling from the eastern Canadian Shelf to the central Scotian Shelf. The model is driven by tides, river discharges, and atmospheric forcing. The model results are validated against observations, including satellite remote sensing data from GHRSST and Aquarius and in situ measurements taken by tide gauges, a marine buoy, ADCPs and CTDs. The ocean circulation model is able to capture variations of sea level, hydrography and the Nova Scotia Current on timescales of days to seasons over the central Scotian Shelf. Model results are used in a process study to examine the effect of tidal mixing and wind-driven coastal upwelling in the formation of cold surface waters along the coast of Nova Scotia
Magnetic fluctuations in n-type high- superconductors reveal breakdown of fermiology
By combining experimental measurements of the quasiparticle and dynamical
magnetic properties of optimally electron-doped PrLaCeCuO
with theoretical calculations we demonstrate that the conventional fermiology
approach cannot possibly account for the magnetic fluctuations in these
materials. In particular, we perform tunneling experiments on the very same
sample for which a dynamical magnetic resonance has been reported recently and
use photoemission data by others on a similar sample to characterize the
fermionic quasiparticle excitations in great detail. We subsequently use this
information to calculate the magnetic response within the conventional
fermiology framework as applied in a large body of work for the hole-doped
superconductors to find a profound disagreement between the theoretical
expectations and the measurements: this approach predicts a step-like feature
rather than a sharp resonance peak, it underestimates the intensity of the
resonance by an order of magnitude, it suggests an unreasonable temperature
dependence of the resonance, and most severely, it predicts that most of the
spectral weight resides in incommensurate wings which are a key feature of the
hole-doped cuprates but have never been observed in the electron-doped
counterparts. Our findings strongly suggest that the magnetic fluctuations
reflect the quantum-mechanical competition between antiferromagnetic and
superconducting orders.Comment: 10 pages, 9 figures, 1 tabl
Systematic Analysis of the Multiple Bioactivities of Green Tea through a Network Pharmacology Approach
During the past decades, a number of studies have demonstrated multiple beneficial health effects of green tea. Polyphenolics are the most biologically active components of green tea. Many targets can be targeted or affected by polyphenolics. In this study, we excavated all of the targets of green tea polyphenolics (GTPs) though literature mining and target calculation and analyzed the multiple pharmacology actions of green tea comprehensively through a network pharmacology approach. In the end, a total of 200 Homo sapiens targets were identified for fifteen GTPs. These targets were classified into six groups according to their related disease, which included cancer, diabetes, neurodegenerative disease, cardiovascular disease, muscular disease, and inflammation. Moreover, these targets mapped into 143 KEGG pathways, 26 of which were more enriched, as determined though pathway enrichment analysis and target-pathway network analysis. Among the identified pathways, 20 pathways were selected for analyzing the mechanisms of green tea in these diseases. Overall, this study systematically illustrated the mechanisms of the pleiotropic activity of green tea by analyzing the corresponding “drug-target-pathway-disease” interaction network
The Hidden Nematic Fluctuations in the Triclinic (Ca0.85La0.15)10(Pt3As8)(Fe2As2)5 Superconductor Revealed by Ultrafast Optical Spectroscopy
We reported the quasiparticle relaxation dynamics of an optimally doped
triclinic iron-based superconductor
(CaLa)(PtAs)(FeAs) with bulk
= 30 K using polarized ultrafast optical pump-probe spectroscopy. Our results
reveal anisotropic transient reflectivity induced by nematic fluctuations
develops below 120 K and persists in the superconducting
states. Measurements under high pump fluence reveal three distinct, coherent
phonon modes at frequencies of 1.6, 3.5, and 4.7 THz, corresponding to
, , and modes, respectively. The high-frequency
mode corresponds to the -axis polarized vibrations of FeAs
planes with a nominal electron-phonon coupling constant
0.139 0.02. Our findings suggest that the superconductivity and
nematic state are compatible but competitive at low temperatures, and the
phonons play an important role in the formation of Cooper pairs in
(CaLa)(PtAs)(FeAs).Comment: 6 pages, 3 figures and Supplemental Material