1,093 research outputs found

    Criteria and geological setting for the generic geothermal underground research laboratory, GEOLAB

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    High flow rate injection and related hydromechanical interaction are the most important factors in reservoir development of Enhanced Geothermal Systems (EGS). GeoLaB, a new generic geothermal underground research laboratory (URL), is proposed for controlled high flow rate experiments (CHFE) to address limited comprehension of coupled processes connected to EGS reservoir flow conditions. As analogue for typical EGS development, CHFE require specific hydromechanical conditions including a connected fracture network in crystalline basement rock, sufficient hydraulic fracture transmissivities, a strike-slip to normal faulting tectonic regime, controllable hydraulic boundary conditions, and hydrothermal alteration fracture fillings that improve conditions for hydromechanical interaction. With the aim to identify most appropriate areas for future site selection, four criteria have been established based on the EGS reference site of Soultz. Two URLs in crystalline basement worldwide approximate the requirements of a new generic GeoLaB and may be used for accompanying experimentation. Besides favourable geological, hydraulic, and stress conditions, the vicinity to long-term EGS production favours the southern Black Forest as potential region for GeoLaB. Therefore, an exemplary site assessment has been carried out at “Wilhelminenstollen” in the southern Black Forest (Germany). New remote sensing, hydrochemical, and geophysical analyses as well as reactivation potential, and stress modelling were added to complement existing geological and hydrogeological information. At this site, reactivation potential analysis reveals two local maxima prone for shear reactivation as strike-slip faults. The highest lineament density is observed for the N110°E strike direction that is associated with both slip and dilation tendency maxima. Clay minerals occur in fractures and the matrix. Local, partly water-bearing fractures, when partly filled with ore minerals, were connected to veins in the tunnel using shallow geophysical methods. Hydrochemical data reveal infiltration of the tunnel water from at least 500 m above the tunnel. The results suggest a crystalline basement with a fracture network that is regionally connected and water-conducting. Hydraulic conductivity in the southern Black Forest granite is estimated to amount to about 4.5·10−8 m s−1 at 500 m depth. The hydraulic boundary conditions exclude unknown drainage. Analyses of the influence of topography on orientation and magnitude of the maximum stress indicate a minimum overburden of about 500 m for regional reactivation to be valid. In conclusion, the southern Black Forest and in particular “Wilhelminenstollen” offers favourable condition for CHFE. Final decision on the GeoLaB site is to be drawn from forthcoming exploration wells

    The Potential of Depleted Oil Reservoirs for High-Temperature Storage Systems

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    HT-ATES (high-temperature aquifer thermal energy storage) systems are a future option to shift large amounts of high-temperature excess heat from summer to winter using the deep underground. Among others, water-bearing reservoirs in former hydrocarbon formations show favorable storage conditions for HT-ATES locations. This study characterizes these reservoirs in the Upper Rhine Graben (URG) and quantifies their heat storage potential numerically. Assuming a doublet system with seasonal injection and production cycles, injection at 140 °C in a typical 70 °C reservoir leads to an annual storage capacity of up to 12 GWh and significant recovery efficiencies increasing up to 82% after ten years of operation. Our numerical modeling-based sensitivity analysis of operational conditions identifies the specific underground conditions as well as drilling configuration (horizontal/vertical) as the most influencing parameters. With about 90% of the investigated reservoirs in the URG transferable into HT-ATES, our analyses reveal a large storage potential of these well-explored oil fields. In summary, it points to a total storage capacity in depleted oil reservoirs of approximately 10 TWh a−1, which is a considerable portion of the thermal energy needs in this area

    Selective Silica Removal in Geothermal Fluids : Implications for Applications for Geothermal Power Plant Operation and Mineral Extraction

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    Raw material extraction from geothermal fluids often comprises concentrating and cooling steps, which increases the risk of silica scaling formation. However, existing silica removal strategies do not consider the impact on raw material extraction. In this study, the applicability and element-selectivity of three silica removal techniques (seed-induced, lime and caustic precipitation) were tested in batch experiments using synthetic and natural geothermal fluid samples. Increasing the pH-value to 10.5 and the Ca/Si ratio > 1.25 was found to mitigate silica scaling effectively via formation of calcium-silicate-hydrate phases (C-S-H phases). The developed silica removal process does not affect the raw materials and is therefore suitable for brine mining purposes

    Impact of Beta-Amyloid-Specific Florbetaben PET Imaging on Confidence in Early Diagnosis of Alzheimer’s Disease

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    BACKGROUND: Early diagnosis of Alzheimer's disease (AD) may be corroborated by imaging of beta-amyloid plaques using positron emission tomography (PET). Here, we performed an add-on questionnaire study to evaluate the relevance of florbetaben imaging (BAY 949172) in diagnosis and consecutive management of probable AD patients. METHODS: AD patients with a clinical diagnosis in accordance with the NINCDS-ADRDA criteria or controls were imaged using florbetaben. Referring physicians were asked on a voluntary basis about their confidence in initial diagnosis, significance of PET imaging results, and their anticipated consequences for future patient care. RESULTS: 121 questionnaires for probable AD patients and 80 questionnaires for controls were evaluated. In 18% of patients who had initially received the diagnosis of probable AD, PET scans were rated negative, whereas in controls 18% of scans were positive. An increase in confidence in the initial diagnosis was frequently reported (80%). Imaging results had a significant impact on the intended patient care, as judged by the referring physicians; this was most prominent in those patients with a contradicting scan and/or a low confidence in the initial diagnosis. CONCLUSION: Florbetaben amyloid imaging increases the overall confidence in diagnosis of AD and may frequently influence clinical decisions and patient management

    A systematic review protocol on the effectiveness of therapeutic exercises utilised by physiotherapists to improve function in patients with burns

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    Background: Therapeutic exercises play a crucial role in the management of burn injuries. The broad objective of this review is to systematically evaluate the effectiveness, safety and applicability to low-income countries of therapeutic exercises utilised by physiotherapists to improve function in patients with burns. Population = adults and children/adolescents with burns of any aspect of their bodies. Interventions = any aerobic and/or strength exercises delivered as part of a rehabilitation programme by anyone (e.g. physiotherapists, occupational therapists, nurses, doctors, community workers and patients themselves). Comparators = any comparator. Outcomes = any measure of outcome (e.g. quality of life, pain, muscle strength, range of movement, fear or quality of movement). Settings = any setting in any country. Methods/design: A systematic review will be conducted by two blinded independent reviewers who will search articles on PubMed, CiNAHL, Cochrane library, Medline, Pedro, OTseeker, EMBASE, PsychINFO and EBSCOhost using predefined criteria. Studies of human participants of any age suffering from burns will be eligible, and there will be no restrictions on total body surface area. Only randomised controlled trials will be considered for this review, and the methodological quality of studies meeting the selection criteria will be evaluated using the Cochrane Collaboration tool for assessing risk of bias. The PRISMA reporting standards will be used to write the review. A narrative analysis of the findings will be done, but if pooling is possible, meta-analysis will be considered. Discussion: Burns may have a long-lasting impact on both psychological and physical functioning and thus it is important to identify and evaluate the effects of current and past aerobic and strength exercises on patients with burns. By identifying the characteristics of effective exercise programmes, guidelines can be suggested for developing intervention programmes aimed at improving the function of patients with burns. The safety and precautions of exercise regimes and the optimal frequency, duration, time and intensity will also be examined to inform further intervention. Systematic review registration. PROSPERO CDR42016048370

    Early Pliocene vegetation and hydrology changes in western equatorial South America

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    During the early Pliocene, two major tectonic events triggered a profound reorganization of ocean and atmospheric circulation in the eastern equatorial Pacific (EEP), in the Caribbean Sea, and on adjacent land masses: the progressive closure of the Central American Seaway (CAS) and the uplift of the Northern Andes. These affected, among other things, the mean latitudinal position of the Intertropical Convergence Zone (ITCZ). The direction of an ITCZ shift, however, is still debated, as numeric modeling results and paleoceanographic data indicate shifts in opposite directions. To provide new insights into this debate, an independent hydrological record of western equatorial South America was generated. Vegetation and climate of this area were reconstructed by pollen analysis of 46 samples from marine sediments of Ocean Drilling Program (ODP) Hole 1239A from the EEP comprising the interval between 4.7 and 4.2&thinsp;Ma. The study site is sensitive to latitudinal ITCZ shifts insofar as a southward (northward) shift would result in increased (decreased) precipitation over Ecuador. The presented pollen record comprises representatives from five ecological groups: lowland rainforest, lower montane forest, upper montane forest, pĂĄramo, and broad range taxa. A broad tropical rainforest coverage persisted in the study area throughout the early Pliocene, without significant open vegetation beyond the pĂĄramo. Between 4.7 and 4.42&thinsp;Ma, humidity increases, reaching its peak around 4.42&thinsp;Ma and slightly decreasing again afterwards. The stable, permanently humid conditions are rather in agreement with paleoceanographic data, indicating a southward shift of the ITCZ, possibly in response to CAS closure. The presence of pĂĄramo vegetation indicates that the Ecuadorian Andes had already reached considerable elevation by the early Pliocene. Future studies could extend the hydrological record of the region further back into the late Miocene to see if a more profound atmospheric response to tectonic changes occurred earlier.</p

    The Arabidopsis NOT4A E3 ligase promotes PGR3 expression and regulates chloroplast translation

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    Chloroplast function requires the coordinated action of nuclear- and chloroplast-derived proteins, including several hundred nuclear-encoded pentatricopeptide repeat (PPR) proteins that regulate plastid mRNA metabolism. Despite their large number and importance, regulatory mechanisms controlling PPR expression are poorly understood. Here we show that the Arabidopsis NOT4A ubiquitin-ligase positively regulates the expression of PROTON GRADIENT REGULATION 3 (PGR3), a PPR protein required for translating several thylakoid-localised photosynthetic components and ribosome subunits within chloroplasts. Loss of NOT4A function leads to a strong depletion of cytochrome b6f and NAD(P)H dehydrogenase (NDH) complexes, as well as plastid 30 S ribosomes, which reduces mRNA translation and photosynthetic capacity, causing pale-yellow and slow-growth phenotypes. Quantitative transcriptome and proteome analysis of the not4a mutant reveal it lacks PGR3 expression, and that its molecular defects resemble those of a pgr3 mutant. Furthermore, we show that normal plastid function is restored to not4a through transgenic PGR3 expression. Our work identifies NOT4A as crucial for ensuring robust photosynthetic function during development and stress-response, through promoting PGR3 production and chloroplast translatio
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