1,341 research outputs found

    Determination of bulk discharge current in the dielectric film of MEMS capacitive switches

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    The present work presents a new method to calculate the discharge current in the bulk of dielectric films of MEMS capacitive switches. This method takes into account the real MEMS switch with non uniform trapped charge and air gap distributions. Assessment of switches with silicon nitride dielectric film shows that the discharge current transient seems to obey the stretched exponential law. The decay characteristics depend on the polarization field’s polarity, a fact comes along with experimental results obtained from thermally stimulated depolarization currents (TSDC) method used in MIM capacitors

    Predicting the solvation of organic compounds in aqueous environments: from alkanes and alcohols to pharmaceuticals

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    The development of accurate models to predict the solvation, solubility, and partitioning of nonpolar and amphiphilic compounds in aqueous environments remains an important challenge. We develop state-of-the-art group-interaction models that deliver an accurate description of the thermodynamic properties of alkanes and alcohols in aqueous solution. The group-contribution formulation of the statistical associating fluid theory based on potentials with a variable Mie form (SAFT-γ Mie) is shown to provide accurate predictions of the phase equilibria, including liquid–liquid equilibria, solubility, free energies of solvation, and other infinite-dilution properties. The transferability of the model is further exemplified with predictions of octanol–water partitioning and solubility for a range of organic and pharmaceutically relevant compounds. Our SAFT-γ Mie platform is reliable for the prediction of challenging properties such as mutual solubilities of water and organic compounds which can span over 10 orders of magnitude, while remaining generic in its applicability to a wide range of compounds and thermodynamic conditions. Our work sheds light on contradictory findings related to alkane–water solubility data and the suitability of models that do not account explicitly for polarity

    Merthyr Mawr: a case study for the assessment of nitrate at humid dunes in England and Wales

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    Humid dunes in the UK are at risk from nutrient pressures from multiple sources. The Water Framework Directive 2000/60/EC (WFD) requires assessment and identification of these pressures with appropriate measures defined to mitigate against further damage. We discuss the application of nitrate threshold values for the WFD classification, illustrating this with a case study at Merthyr Mawr, South Wales, where ephemeral groundwater discharge from a spring (‘Burrows Well’) sourced within the Carboniferous Limestone, creates a large dune slack. Ecological surveys suggest that the vegetation in this slack was in unfavourable condition, due to high levels of nitrate. Applying the source-pathway-receptor model an investigation was undertaken to improve the conceptual model and assess the significance of damage from groundwater derived nutrients. Results show groundwater nitrate concentrations ~ 10 mg/l as NO3-N feeding the main slack waters. The vegetation survey data shows clear evidence of ecological damage, and the hydrogeological data traces the source of this back to the Carboniferous Limestone aquifer and not the overlying blown sands. Discharging groundwater is the source of the enrichment. Isotopic analysis suggests that the N is derived from inorganic fertilizer and/or atmospheric N. During the first cycle WFD characterisation the unfavourable status of the dunes due to chemical groundwater pressure resulted in a failure of the surrounding groundwater body, which was designated as poor status. The site has been re assessed for the 2nd Cycle WFD characterisation where recently developed nitrate ‘threshold’ values have been applied to assess the significance of damage for groundwater derived nutrients. The surrounding Carboniferous Limestone catchment is complex and could not be sufficiently constrained, thus land management changes could not be targeted. The paucity of historical or repeat vegetation surveys limits our ability to measure change within the dune vegetation and causes difficulties in understanding the impact of multiple pressures

    Local Soft Tissue and Bone Displacements Following Midfacial Bipartition Distraction in Apert Syndrome – Quantification Using a Semi-Automated Method

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    ABSTRACT: Patients with Apert syndrome experience midfacial hypoplasia, hypertelorism, and downslanting palpebral fissures which can be corrected by midfacial bipartition distraction with rigid external distraction device. Quantitative studies typically focus on quantifying rigid advancement and rotation postdistraction, but intrinsic shape changes of bone and soft tissue remain unknown. This study presents a method to quantify these changes. Pre- and post-operative computed tomography scans from patients with Apert syndrome undergoing midfacial bipartition distraction with rigid external distraction device were collected. Digital Imaging and Communications in Medicine files were converted to three-dimensional bone and soft tissue reconstructions. Postoperative reconstructions were aligned on the preoperative maxilla, followed by nonrigid iterative closest point transformation to determine local shape changes. Anatomical point-to-point displacements were calculated and visualized using a heatmap and arrow map. Nine patients were included.Zygomatic arches and frontal bone demonstrated the largest changes. Mid-lateral to supra-orbital rim showed an upward, inward motion. Mean bone displacements ranged from 3.3 to 12.8 mm. Soft tissue displacements were relatively smaller, with greatest changes at the lateral canthi. Midfacial bipartition distraction with rigid external distraction device results in upward, inward rotation of the orbits, upward rotation of the zygomatic arch, and relative posterior motion of the frontal bone. Local movements were successfully quantified using a novel method, which can be applied to other surgical techniques/syndromes

    The coregulator Alien

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    Alien has characteristics of a corepressor for selected members of the nuclear hormone receptor (NHR) superfamily and also for transcription factors involved in cell cycle regulation and DNA repair. Alien mediates gene silencing and represses the transactivation of specific NHRs and other transcription factors to modulate hormone response and cell proliferation. Alien is a highly conserved protein and is expressed in a wide variety of tissues. Knockout of the gene encoding Alien in mice is embryonic lethal at a very early stage, indicating an important evolutionary role in multicellular organisms. From a mechanistic perspective, the corepressor function of Alien is in part mediated by histone deacetylase (HDAC) activity. In addition, Alien seems to modulate nucleosome assembly activity. This suggests that Alien is acting on chromatin not only through recruitment of histone-modifying activities, but also through enhancing nucleosome assembly

    Day-ahead industrial load forecasting for electric RTG cranes

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    Given the increase in international trading and the significant energy and environmental challenges in ports around the world, there is a need for a greater understanding of the energy demand behaviour at ports. The move towards electrified rubber-tyred gantry (RTG) cranes is expected to reduce gas emissions and increase energy savings compared to diesel RTG cranes but it will increase electrical energy demand. Electrical load forecasting is a key tool for understanding the energy demand which is usually applied to data with strong regularities and seasonal patterns. However, the highly volatile and stochastic behaviour of the RTG crane demand creates a substantial prediction challenge. This paper is one of the first extensive investigations into short term load forecasts for electrified RTG crane demand. Options for model inputs are investigated depending on extensive data and correlation analysis. The effect of estimation accuracy of exogenous variables on the forecast accuracy is investigated as well. The models are tested on two different RTG crane data sets that were collected from the Port of Felixstowe in the UK. The results reveal the effectiveness of the forecast models when the estimation of the number of crane moves and container gross weight are accurate
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