Extending the GERG-2008 equation of state: Improved departure function and interaction parameters for (methane+butane)

The Groupe Européen de Recherches Gazières (GERG) 2008 multi-parameter equation of state (EOS) is considered the reference model for the prediction of natural gas mixture properties. However, the limited quality of thermodynamic property data available for many key binary mixtures at the time of its development constrained both its range of validity and achievable uncertainty. The data situation for the binary system (CH4 + C4H10) in particular was identified previously as limiting the ability of the GERG-EOS to describe rich natural gases at low temperatures. Recently, new vapour-liquid equilibrium (VLE) and liquid mixture heat capacity data measured at low temperatures and high pressures have been published that significantly improve the data situation for this crucial binary, allowing erroneous literature data to be identified and the predictive behaviour of the GERG-EOS when extrapolated to be tested. The 10 basis functions in the generalised departure function used by the GERG-EOS for several binaries including (CH4 + C4H10) were examined to eliminate the term causing a divergence between measured and predicted liquid mixture isobaric heat capacities at T < 150 K. With a simplified nine-term departure function, the maximum relative deviation between the measured and predicted heat capacities was reduced from nearly (110 to 7) %. The interaction parameters in the GERG equation were also re-determined by including, for the first time for this binary, reliable low temperature VLE data together with most of the other high temperature data used in the original development of the model. The new interaction parameters for (CH4 + C4H10) reduced the relative deviation of bubble point pressures measured and calculated at T = 244 K from (9 to 1.4) %, without affecting the accuracy of property predictions at higher temperature

The thermal regime around buried submarine high voltage cables

The expansion of offshore renewable energy infrastructure and the need for trans-continental shelf power transmission require the use of submarine High Voltage (HV) cables. These cables have maximum operating surface temperatures of up to 70°C and are typically buried 1–2 m beneath the seabed, within the wide range of substrates found on the continental shelf. However, the heat flow pattern and potential effects on the sedimentary environments around such anomalously high heat sources in the near surface sediments are poorly understood. We present temperature measurements from a 2D laboratory experiment representing a buried submarine HV cable, and identify the thermal regimes generated within typical unconsolidated shelf sediments—coarse silt, fine sand and very coarse sand. We used a large (2 × 2.5 m) tank filled with water-saturated spherical glass beads (ballotini) and instrumented with a buried heat source and 120 thermocouples, to measure the time-dependent 2D temperature distributions. The observed and corresponding Finite Element Method (FEM) simulations of the steady state heat flow regimes, and normalised radial temperature distributions were assessed. Our results show that the heat transfer and thus temperature fields generated from submarine HV cables buried within a range of sediments are highly variable. Coarse silts are shown to be purely conductive, producing temperature increases of &gt;10°C up to 40 cm from the source of 60°C above ambient; fine sands demonstrate a transition from conductive to convective heat transfer between c. 20°C and 36°C above ambient, with &gt;10°C heat increases occurring over a metre from the source of 55°C above ambient; and very coarse sands exhibit dominantly convective heat transfer even at very low (c. 7°C) operating temperatures and reaching temperatures of up to 18°C above ambient at a metre from the source at surface temperatures of only 18°C. These findings are important for the surrounding near surface environments experiencing such high temperatures and may have significant implications for chemical and physical processes operating at the grain and sub-grain scale; biological activity at both micro-faunal and macro-faunal levels; and indeed the operational performance of the cables themselves, as convective heat transport would increase cable current ratings, something neglected in existing standards

The response of the magnetosphere to the passage of a coronal mass ejection on March 20-21 1990

International audienceThe geomagnetic response to the passage of a coronal mass ejection (CME) is studied. The passage of the CME resulted in a storm sudden commencement (SSC) at 2243 UT on March 20 1990 with disturbed magnetic activity during the following 24 h. The auroral, sub-auroral and equatorial magnetic response to the southward turning at 1314 (±5) UT on March 21 and the equatorial response to the southward turning associated with the SSC on 20 March are discussed in terms of existing models. It is found that the auroral and sub-auroral response to the southward turning associated with the SSC is a factor 2 or more quicker than normal due to the shock in the solar wind dynamic pressure. The low-latitude response time to the southward turning, characterised by Dst and the magnetopause current corrected Dst*, is unaffected by the shock. Dst and Dst*, characteristic of the equatorial magnetic field, responded to the 1314 (±5) UT southward turning prior to the first observed substorm expansion phase onset, suggesting that a dayside loading process was responsible for the initial enhancement in the ring current rather than nightside particle injection. The response time of the auroral and sub-auroral magnetic field to the southward turning at 1314 (±5) UT on March 21 is measured at a variety of longitudes and latitudes. The azimuthal propagation velocity of the response to the southward turning varied considerably with latitude, ranging from ~8 km s?1 at 67°N to ~4 km s?1 at 55°N. The southward velocity of the equatorward boundary of the northern polar convection pattern has been measured. This velocity was ~1.2 km s?1 at 1600 MLT, although there was evidence that this may vary at different local times

Thin film porous membranes for catalytic sensors

This paper reports on new and surprising experimental data for catalytic film gas sensing resistors coated with nanoporous sol-gel films to impart selectivity and durability to the sensor structure. This work is the result of attempts to build selectivity and reactivity to the surface of a sensor by modifying it with a series of sol-gel layers. The initial sol-gel SiO{sub 2} layer applied to the sensor surprisingly showed enhanced O{sub 2} interaction with H{sub 2} and reduced susceptibility to poisons such as H{sub 2}S

Global ice sheet modeling

The University of Maine conducted this study for Pacific Northwest Laboratory (PNL) as part of a global climate modeling task for site characterization of the potential nuclear waste respository site at Yucca Mountain, NV. The purpose of the study was to develop a global ice sheet dynamics model that will forecast the three-dimensional configuration of global ice sheets for specific climate change scenarios. The objective of the third (final) year of the work was to produce ice sheet data for glaciation scenarios covering the next 100,000 years. This was accomplished using both the map-plane and flowband solutions of our time-dependent, finite-element gridpoint model. The theory and equations used to develop the ice sheet models are presented. Three future scenarios were simulated by the model and results are discussed

Computational investigations of dispersion interactions between small molecules and graphene-like flakes

We investigate dispersion interactions in a selection of atomic, molecular, and molecule–surface systems, comparing high-level correlated methods with empirically corrected density functional theory (DFT). We assess the efficacy of functionals commonly used for surface-based calculations, with and without the D3 correction of Grimme. We find that the inclusion of the correction is essential to get meaningful results, but there is otherwise little to distinguish between the functionals. We also present coupled-cluster quality interaction curves for H2, NO2, H2O, and Ar interacting with large carbon flakes, acting as models for graphene surfaces, using novel absolutely localized molecular orbital based methods. These calculations demonstrate that the problems with empirically corrected DFT when investigating dispersion appear to compound as the system size increases, with important implications for future computational studies of molecule–surface interactions

Rapid modification of the bone microenvironment following short-term treatment with Cabozantinib in vivo

Introduction: Bone metastasis remains incurable with treatment restricted to palliative care. Cabozantinib (CBZ) is targeted against multiple receptor tyrosine kinases involved in tumour pathobiology, including hepatocyte growth factor receptor (MET) and vascular endothelial growth factor receptor 2 (VEGFR-2). CBZ has demonstrated clinical activity in advanced prostate cancer with resolution of lesions visible on bone scans, implicating a potential role of the bone microenvironment as a mediator of CBZ effects. We characterised the effects of short-term administration of CBZ on bone in a range of in vivo models to determine how CBZ affects bone in the absence of tumour. Methods: Studies were performed in a variety of in vivo models including male and female BALB/c nude mice (age 6– 17-weeks). Animals received CBZ (30 mg/kg, 5× weekly) or sterile H2O control for 5 or 10 days. Effects on bone integrity (μCT), bone cell activity (PINP, TRAP ELISA), osteoblast and osteoclast number/mm trabecular bone surface, area of epiphyseal growth plate cartilage, megakaryocyte numbers and bone marrow composition were assessed. Effects of longer-term treatment (15-day & 6-week administration) were assessed in male NOD/SCID and beige SCID mice. Results: CBZ treatment had significant effects on the bone microenvironment, including reduced osteoclast and increased osteoblast numbers compared to control. Trabecular bone structure was altered after 8 administrations. A significant elongation of the epiphyseal growth plate, in particular the hypertrophic chondrocyte zone, was observed in all CBZ treated animals irrespective of administration schedule. Both male and female BALB/c nude mice had increased megakaryocyte numbers/mm2 tissue after 10-day CBZ treatment, in addition to vascular ectasia, reduced bone marrow cellularity and extravasation of red blood cells into the extra-vascular bone marrow. All CBZinduced effects were transient and rapidly lost following cessation of treatment. Conclusion: Short-term administration of CBZ induces rapid, reversible effects on the bone microenvironmentin vivo highlighting a potential role in mediating treatment responses

Functional and molecular analysis of proprioceptive sensory neuron excitability in mice

Neurons located in dorsal root ganglia (DRG) are crucial for transmitting peripheral sensations such as proprioception, touch, temperature, and nociception to the spinal cord before propagating these signals to higher brain structures. To date, difficulty in identifying modality-specific DRG neurons has limited our ability to study specific populations in detail. As the calcium-binding protein parvalbumin (PV) is a neurochemical marker for proprioceptive DRG cells we used a transgenic mouse line expressing green fluorescent protein (GFP) in PV positive DRGs, to study the functional and molecular properties of putative proprioceptive neurons. Immunolabeled DRGs showed a 100% overlap between GFP positive (GFP+) and PV positive cells, confirming the PVeGFP mouse accurately labeled PV neurons. Targeted patch-clamp recording from isolated GFP+ and GFP negative (GFP−) neurons showed the passive membrane properties of the two groups were similar, however, their active properties differed markedly. All GFP+ neurons fired a single spike in response to sustained current injection and their action potentials (APs) had faster rise times, lower thresholds and shorter half widths. A hyperpolarization-activated current (Ih) was observed in all GFP+ neurons but was infrequently noted in the GFP− population (100% vs. 11%). For GFP+ neurons, Ih activation rates varied markedly, suggesting differences in the underlying hyperpolarization-activated cyclic nucleotide-gated channel (HCN) subunit expression responsible for the current kinetics. Furthermore, quantitative polymerase chain reaction (qPCR) showed the HCN subunits 2, 1, and 4 mRNA (in that order) was more abundant in GFP+ neurons, while HCN 3 was more highly expressed in GFP− neurons. Likewise, immunolabeling confirmed HCN 1, 2, and 4 protein expression in GFP+ neurons. In summary, certain functional properties of GFP+ and GFP− cells differ markedly, providing evidence for modality-specific signaling between the two groups. However, the GFP+ DRG population demonstrates considerable internal heterogeneity when hyperpolarization-activated cyclic nucleotide-gated channel (HCN channel) properties and subunit expression are considered. We propose this heterogeneity reflects the existence of different peripheral receptors such as tendon organs, muscle spindles or mechanoreceptors in the putative proprioceptive neuron population

Assessing ice sheet models against the landform record: the Likelihood of Accordant Lineations Analysis (LALA) tool

Palaeo-ice sheets leave behind a rich database regarding their past behaviour, recorded in the landscape in the form of glacial geomorphology. The most numerous landform created by these ice sheets are subglacial lineations, which generate snapshots of the direction of ice flow at fixed (yet typically unknown) points in time. Despite their relative density within the landform record, the information provided by subglacial lineations is currently underutilised in tests of numerical ice sheet models. To some extent, this is a consequence of ongoing debate regarding lineation formation, but predominantly, it reflects the lack of rigorous model-data comparison techniques that would enable lineation information to be properly integrated. Here, we present the Likelihood of Accordant Lineations Analysis (LALA) tool. LALA provides a statistically rigorous measure of the log-likelihood of a supplied ice sheet simulation through comparison of simulation output with both the location and direction of observed lineations. Given an ensemble of ice sheet simulations, LALA provides a formal, and statistically underpinned, quantitative assessment of each simulation's quality-of-fit to mapped lineations. This enables a comparison of each simulation's relative plausibility, including identification of the most likely ice sheet simulations amongst the ensemble. This is achieved by modelling lineation formation as a marked Poisson point process and comparison of observed to modelled flow directions using the von Mises distribution. LALA is flexible—users can adapt parameters to account for differing assumptions regarding lineation formation, and for variations in the level of precision required for differing model-data comparison experiments. We provide guidelines and rationale for assigning parameter values, including an assessment of the variability between users when mapping lineations. Finally, we demonstrate the utility of LALA through application to an ensemble of simulations of the last British-Irish Ice Sheet. This comparison highlights the benefits of LALA over previous tools and demonstrates some of the considerations of experimental design required when identifying the fit between ice sheet model simulations and the landform record

Towards practice-based studies of HRM: an actor-network and communities of practice informed approach

HRM may have become co-terminus with the new managerialism in the rhetorical orthodoxies of the HRM textbooks and other platforms for its professional claims. However, we have detailed case-study data showing that HR practices can be much more complicated, nuanced and indeed resistive toward management within organizational settings. Our study is based on ethnographic research, informed by actor-network theory and community of practice theory conducted by one of the authors over an 18-month period. Using actor-network theory in a descriptive and critical way, we analyse practices of managerial resistance, enrolment and counter-enrolment through which an unofficial network of managers used a formal HRM practice to successfully counteract the official strategy of the firm, which was to close parts of a production site. As a consequence, this network of middle managers effectively changed top management strategy and did so through official HRM practices, coupled with other actor-network building processes, arguably for the ultimate benefit of the organization, though against the initial views of the top management. The research reported here, may be characterized as a situated study of HRM-in-practice and we draw conclusions which problematize the concept of HRM in contemporary management literature