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Rare earth elements (REEs) are critical components in advanced electronics, clean energy technologies, and national energy and economic security. The global supply situation of these strategically valuable elements remains critical as the market is largely monopolistic. Thus, to alleviate the dependence on global imports, investments are being made in the research and development of innovative and cost-effective technologies for the indigenous processing and recovery of REEs from alternate sources that are cheap and abundant. Numerous research findings have identified potential benefits and proven the technological feasibility of extracting and selectively concentrating REEs from coal byproducts such as preparation plant rejects and acid mine drainage among other sources. Given the relatively low grades, the chemical cost associated with hydrometallurgical extraction of REEs from coal-derived feedstocks is excessively high for commercial extraction. Recent studies have been successful in increasing REE recovery and leaching kinetics by oxidation pretreatment of the coal-based feed. However, the reasons behind the positive oxidation effects have yet to be systematically studied to provide an understanding of the mineralogical changes and to utilize the knowledge for process development. Therefore, the current investigation aimed to comprehensively study the effect of oxidation parameters on the leaching characteristics of REEs contained in coal-based feedstocks. Low and high-temperature oxidation methods were evaluated and assessed to quantify their impacts on the recovery of REEs as well as the extraction of common contaminant elements (aluminum, calcium, and iron) found in a coal-derived pregnant leach solution. Initially, the effect of low-temperature plasma (LTP) was analyzed for improving the REE leaching recovery from coal coarse rejects. The refuse material originating from the West Kentucky No.13 (WK-13) and Fire Clay coal seams were oxidized by LTP and leached separately using different lixiviants, i.e., deionized water, 0.1M ammonium sulfate, and 1.2M sulfuric acid, at 75°C in a sequential manner. LTP pretreatment was found to significantly enhance REE leaching characteristics for the low ash content, light density fractions of the WK-13 with selectivity towards the heavy REEs that are of critical importance. High heavy REE recovery values from the 1.60 specific gravity (SG) float fraction were positively correlated with a decrease in organic content which was achieved by an increase in LTP treatment time and using both a mild 0.1M ammonium sulfate solution and 1.2M sulfuric acid as lixiviants. This finding indicated a strong affinity of the heavy REEs with the dispersed mineral matter existing within the organic material, which was partially liberated during the LTP treatment. The improvement in REE leachability can be attributed to increased porosity and surface area by LTP treatment as confirmed from surface area analysis and scanning electron micrographs. However, LTP had a limited effect on the high-ash content, heavy-density fractions and provided no significant improvement in leaching characteristics. Similarly, the LTP treatment of the Fire Clay provided no significant improvement in high ash density fractions and marginal benefits for the 1.60 float fraction, which suggests differences in the mode of occurrence of the REEs between the two coal sources. Secondly, calcination at 600-800°C for two hours significantly improved REE leachability for all density fractions in both coals under standard acid leaching conditions. The majority of the heavy REEs were found to be marginally affected by thermal treatment. Additionally, a strong correlation between the light REEs and aluminum suggested a possible association of light REEs with clays. Test results from the parametric program performed based on a Box-Behnken design were used for modeling and optimization of three operating parameters associated with the lab-scale calcination process (temperature (400-800°C), ramp rate (2-10°C/min) and hold time (0-120 min)). The calcination temperatures required for selectively improving REE recovery while minimizing the extraction of contaminant ions were found to be dependent on the mineral composition of the feed. Subsequently, the potential of iron contamination removal from the hydrometallurgical process by calcination and magnetic separation was investigated. The calcined products at 400-500°C of the pyrite-rich 2.20 SG sink fraction of the WK-13 seam provided an opportunity for REE enrichment in the tailings by magnetic separation. The magnetic fraction had a higher recovery of heavy REEs and iron as compared to the feed and the nonmagnetic fraction. The improvements in the heavy REE leaching characteristics resulted from the transformation of pyrites to intermediate hematite at high temperatures under the presence of oxygen. A novel flowsheet was proposed by integrating calcination and magnetic separation with a typical hydrometallurgical process for efficient extraction of REEs from a pyrite-rich feedstock. Finally, the effect of calcination atmosphere (oxidizing/inert) on enhancing the REE leachability was evaluated at high temperatures. The REE recovery for high ash fractions (>2.00 SG) of a Fire Clay seam source was significantly improved at 1000°C under an inert atmosphere, which contrasted with the poor recovery values achieved under oxygen due to sintering of the clay surfaces. The benefits of the heavy REE leaching from the low ash density fractions were realized only when the organic matter was removed under an oxidizing environment suggesting the association of heavy REEs with the organic material. As a means of further identifying modes of occurrence, an excellent correlation was discovered between the leaching behavior of the bituminous coal sources and natural clay minerals in relation to the recovery of the heavy REEs and overall REE leaching kinetics. A characteristic exothermic peak for the phase transformation of meta kaolinite to mullite was observed for calcination under an inert environment for the density fractions of the two coal sources. Selectivity towards REEs associated with the clay samples was obtained by calcination at 500-800°C and using a short leaching time. Fe contamination can be controlled by converting the pyrite to crystalline hematite at temperatures >600°C using standard air and by calcination at lower temperatures (400-500°C) for Fe that is associated with clay minerals., © 2021 Tushar Gupta

Two Dimensional (2D) pnictogens are predicted to have thickness dependent transitionsin electronic properties and hence constitute key interest in energy and electronics applications. The ultra-smooth surface of 2D materials like graphene facilitates the realization of high lattice mismatched layers to grow atop each other via Van-der-Waalsepitaxy. The thus grown polymorphic structures of these pnictogens on graphene have also been found to be superior anode materials for batteries. This study aims to realize such heterostructures and investigate the properties of their rich phases.Aberration corrected atomically resolved scanning transmission electron microscopy was employed to probe the evolution of structure and morphology at the interfaces inthe 2D antimonene (Sb) - graphene heterostructures and bismuthene (Bi) - grapheneheterostructures grown via a physical vapor deposition technique of thermalevaporation. These pnictogens were found to simultaneously exist in two different textures of their thermodynamically preferred layered 2D ��-phase, namely: ��-(001) and ��-[2-21] phases on graphene. Importantly, a strong indication for preferred relative crystallographic orientations with respect to the supporting graphene monolayer lattice was observed for both the phases, indicating the existence of rotational Van-der-Waalsepitaxy in 2D Sb/Bi - graphene heterostructures. The studies here also highlight other interesting properties of the grown pnictogens: (1) exceptional resilience of both phases against environmental oxidation was revealed via electron energy loss spectroscopy (both low-loss and core-loss); (2) electron beam induced in situ crystallizations processes and associated plasmon dynamics were studied with valence electron energyloss spectroscopy etc. Sensitivity of exact Sb / Bi growth results for both phases ongraphene on employed processing and substrate properties incl., notably, the nature of the support type underneath the direct graphene support was found. This work there by provides fundamental insights into the phase wealth and epitaxy landscape in 2D Sb/Biand 2D Sb/Bi- graphene heterostructures.As another promising cost-effective and rational technique to scalable synthesize 2D materials, route of liquid phase exfoliation was explored to exfoliate pnictogens, where exfoliation of Bi under the here adopted processing conditions resulted in the synthesis of laterally large 2D sheets of bismuth-oxy-carbonate. The efficacy of five different common solvents in exfoliating Bi was examined. The synthesized exfoliated sheets/flakes of bismuth-oxy-carbonates were later utilized as catalyst component by integrating them with titanium dioxide as photocatalyst via simple mix and match method. The composite showed improved hydrogen evolution rates upon watersplittingas compared to respective individual components. This work there by furtherdemonstrates the application of bismuth-oxy-carbonate as a catalyst component to drive photocatalytic water splitting reactions to produce hydrogen.

Laterally large (~3 micrometers), atomically-thin two-dimensional (2D) Bi2O2CO3 nanosheets (2D bismuth oxycarbonate, 2D bismutite) are fabricated via sonochemically-assisted template-free synthesis. Key to the synthesis of the freestanding, laterally large 2D Bi2O2CO3 nanosheets from bulk Bi powder is choice of suspension medium, controlled reaction temperatures and several hours processing time. Lateral sizes of 2D Bi2O2CO3 can be controlled between micrometer-sized nanosheets and tens of nm sized nanoflakes solely based on the choice of suspension medium. The here introduced 2D Bi2O2CO3 nanosheets/-flakes are then hybridized by a simple mix-and-match approach with TiO2 nanoparticles for testing in suspension-type photocatalytic hydrogen production via water splitting. This introduces the 2D Bi2O2CO3 with TiO2 as a promising noble-metal-free co-catalyst for photocatalytic hydrogen evolution. Our results enrich the fabrication toolbox of emerging 2D pnictogen oxycarbonates towards large 2D nanosheets and demonstrate the promising potential of 2D Bi2O2CO3 as an advantageous (co-)catalyst for hydrogen evolution in photocatalytic water splitting.

Bulk chalcogenide perovskite BaZrS3 (BZS), with a direct band gap in visible region, is an important photovoltaic material, albeit with limited applicability owing to its antiferroelectric (AF) nature. Presently, ferroelectric (FE) perovskite-based photovoltaics are attracting enormous attention for environmental stability and better energy conversion efficiency through enhanced charge separation, owing to loss of center of inversion symmetry. We report on antiferroelectric-ferroelectric (AF-FE) phases of BZS thin film, grown with chemical vapor deposition (CVD), using temperature-dependent Raman investigations and first-principles calculations. The origin of FE phases is established from anomalous behavior of A7g ~ 300 cm-1 and B1g5 ~ 420 cm-1 modes, which involves the vibration of atoms at apical site of ZrS6 octahedra. Additionally, below 60 K, B1g1 and B2g2 ( ~ 85 cm-1) modes appear whereas B12g (~ 60 cm-1) disappears to stabilize the Pnma structure against ferroelectricity by local distortion. Here, B2g2 and B1g2 involve vibrations of Ba atoms in AF manner while B1g1 involves, in addition, the rotation of octahedra as well. Our first-principles calculations confirm that FE appears as a result of loss of center of inversion symmetry in ZrS6 octahedra due to existence of oxygen (O) impurities placed locally at apical sites of sulfur (S) atom., 7 figurs

The abstract is available here: https://uscholar.univie.ac.at/o:930864

The segregation of brain fiber tractography data into distinct and anatomically meaningful clusters can help to comprehend the complex brain structure and early investigation and management of various neural disorders. We propose a novel stacked bidirectional long short-term memory(LSTM) based segmentation network, (BrainSegNet) for human brain fiber tractography data classification. We perform a two-level hierarchical classification a) White vs Grey matter (Macro) and b) White matter clusters (Micro). BrainSegNet is trained over three brain tractography data having over 250,000 fibers each. Our experimental evaluation shows that our model achieves state-of-the-art results. We have performed inter as well as intra class testing over three patient's brain tractography data and achieved a high classification accuracy for both macro and micro levels both under intra as well as inter brain testing scenario., Deep Learning in Irregular Domains - British Machine Vision Conference (DLID-BMVC)

Exposure of an Rh negative mother to red blood cells (RBCs) of an Rh positive fetus results in alloimmunization and development of anti-RhD antibodies. The anti-RhD antibodies cause hemolytic disease of the new born babies during subsequent pregnancies. Current prophylactic treatment involves polyclonal anti-RhD IgG purified from plasma of humans and is administered in approximately 20% of pregnancies. While the current prophylaxis is effective, it involves the use of human plasma and non-RhD specific antibodies, thus posing a risk of transmitting infections and undesired antibody reactions. Moreover, there is a serious scarcity of plasma donors to meet the requirement of anti-RhD antibodies. In this study we propose to discover and develop anti-RhD monoclonal human antibodies to replace the current polyclonal prophylaxis. We are using humanized BLT mice (fetal CD34+ stem cells, liver and thymus) reconstituted with RhD negative donor material and were immunized by using adenovirus containing RhD transgene. Serum samples were collected after 4-6 weeks of immunization. Our results show that the RhD immunized mice had considerably higher titer of IgG and IgA antibodies in the serum compared to the control, suggesting an immune response developed upon immunization. Splenocytes from antibody producing mice will be fused with a human fusion partner for the isolation of hybridomas producing human monoclonal antibodies. The immunoreactivity and functional activity of these antibodies will be discussed.

The purpose of this study is to develop a method to qualitatively and quantitatively measure and assess the field testing of a diagnostic tool by identifying the parameters that are relevant to assess a field test. The study is conducted at Scania CV AB, Södertälje, Sweden, a world leading manufacturer of trucks, buses and industrial and marine engines, where a method to assess the field test of their diagnostic currently does not exist. The study follows a deductive approach while taking a positivistic and hermeneutic perspective. The relevant theories and literature such as quality development and software testing are described to give a better understanding of the study. The study is conducted in four main steps- description of present situation, situation analysis, development of the assessment approach or framework and evaluation of the framework. The empirical information gathered from numerous interviews and meetings is presented in the description of present situation along with the various data sources available. The collected data from different databases is analysed where hypotheses are formulated based on the different influencing parameters for field testing. The correlations between the parameters are then calculated and analysed to verify the hypothesis as True or False. The ECU updates are also analysed to show that the ECU updates performed during field testing is a good representation of the actual usage after release. The framework to assess the field test is then developed using the available data and analysis made. A holistic view is taken to include the processes before and after the field test in the framework. The framework is in the form of an Excel workbook where data is either copied from databases or manually entered and relevant graphs describing the field test are generated automatically. The time period to be displayed on the graphs can be selected manually. This gives a good base to take decisions about how a field test has gone and whether or not the software is ready for release. Based on the correlation of the different parameters, a table with different key values of how much field test usage that should be conducted based on the number of implemented change requests are presented. Thus the result is that the most important attributes to consider for a field test are the amount of implemented changes where each field test usage occasion increases the chance of finding potential faults in the software of the diagnostic tool. An unrestricted framework is also described using data that may be available, but currently difficult to utilise effectively. Thus the recommended future work is represented by this framework which describes what information that can be obtained from different data sources and how they can be used to get a detailed understanding of what exactly has been used during field testing as well as after the software has been released. The framework is assessed in the last step and its uses along with limitations are described. The difficulty in describing the success of software testing is also discussed to give a good context to the framework and understand its utility.

【Abstract】Controlling postoperative pain after total hip replacement is important and controversy remains regarding different regimens. By reviewing 18 studies, we attempt to find whether local infiltration analgesia after total hip replacement has any effect on postoperative pain, length of hospital stay and opioid consumption. We conclude that local infi ltration analgesia is an effective method for decreasing postoperative pain. Key words: Arthroplasty, replacement, hip; Analgesia; Pain, postoperative

OpenMI is a widely used standard allowing exchange of data between integrated models, which has mostly been applied to dynamic, deterministic models. Within the FP7 UncertWeb project we are developing mechanisms and tools to support the management of uncertainty in environmental models. In this paper we explore the integration of the UncertWeb framework with OpenMI, to assess the issues that arise when propagating uncertainty in OpenMI model compositions, and the degree of integration possible with UncertWeb tools. In particular we develop an uncertainty-enabled model for a simple Lotka-Volterra system with an interface conforming to the OpenMI standard, exploring uncertainty in the initial predator and prey levels, and the parameters of the model equations. We use the Elicitator tool developed within UncertWeb to identify the initial condition uncertainties, and show how these can be integrated, using UncertML, with simple Monte Carlo propagation mechanisms. The mediators we develop for OpenMI models are generic and produce standard Web services that expose the OpenMI models to a Web based framework. We discuss what further work is needed to allow a more complete system to be developed and show how this might be used practically.

International audience

International audience