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Open AccessReview
Interfacial and Colloidal Forces Governing Oil Droplet Displacement: Implications for Enhanced Oil Recovery
Colloids Interfaces 2018, 2(3), 30; https://doi.org/10.3390/colloids2030030 (registering DOI) -
Abstract
Growing oil demand and the gradual depletion of conventional oil reserves by primary extraction has highlighted the need for enhanced oil recovery techniques to increase the potential of existing reservoirs and facilitate the recovery of more complex unconventional oils. This paper describes the
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Growing oil demand and the gradual depletion of conventional oil reserves by primary extraction has highlighted the need for enhanced oil recovery techniques to increase the potential of existing reservoirs and facilitate the recovery of more complex unconventional oils. This paper describes the interfacial and colloidal forces governing oil film displacement from solid surfaces. Direct contact of oil with the reservoir rock transforms the solid surface from a water-wet to neutrally-wet and oil-wet as a result of the deposition of polar components of the crude oil, with lower oil recovery from oil-wet reservoirs. To enhance oil recovery, chemicals can be added to the injection water to modify the oil-water interfacial tension and solid-oil-water three-phase contact angle. In the presence of certain surfactants and nanoparticles, a ruptured oil film will dewet to a new equilibrium contact angle, reducing the work of adhesion to detach an oil droplet from the solid surface. Dynamics of contact-line displacement are considered and the effect of surface active agents on enhancing oil displacement discussed. The paper is intended to provide an overview of the interfacial and colloidal forces controlling the process of oil film displacement and droplet detachment for enhanced oil recovery. A comprehensive summary of chemicals tested is provided. Full article
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Open AccessArticle
Hydrophobic Forces Are Relevant to Bacteria-Nanoparticle Interactions: Pseudomonas putida Capture Efficiency by Using Arginine, Cysteine or Oxalate Wrapped Magnetic Nanoparticles
Colloids Interfaces 2018, 2(3), 29; https://doi.org/10.3390/colloids2030029 (registering DOI) -
Abstract
Size, shape and surface characteristics strongly affect interfacial interactions, as the presented among iron oxide nanoparticles (NPs) aqueous colloids and bacteria. In other to find the forces among this interaction, we compare three types of surface modified NPs (exposing oxalate, arginine or cysteine
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Size, shape and surface characteristics strongly affect interfacial interactions, as the presented among iron oxide nanoparticles (NPs) aqueous colloids and bacteria. In other to find the forces among this interaction, we compare three types of surface modified NPs (exposing oxalate, arginine or cysteine residues), based on a simple synthesis and derivation procedure, that allows us to obtain very similar NPs (size and shape of the magnetic core). In this way, we assure that the main difference in the synthesized NPs are the oxalate or amino acid residue exposed, an ideal situation to compare their bacterial capture performance, and so too the interactions among them. Field emission scanning electron microscopy showed homogeneous distribution of particle sizes for all systems synthesized, close to 10 nm. Magnetization, zeta potential, Fourier transformed infrared spectrometry and other studies allow us further characterization. Capture experiments of Pseudomonas putida bacterial strain showed a high level of efficiency, independently of the amino acid used to wrap the NP, when compared with oxalate. We show that bacterial capture efficiency cannot be related mostly to the bacterial and NP superficial charge relationship (as determined by z potential), but instead capture can be correlated with hydrophobic and hydrophilic forces among them. Full article
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Open AccessReview
Exotic Parasite Threats to Australia’s Biosecurity—Trade, Health, and Conservation
Trop. Med. Infect. Dis. 2018, 3(3), 76; https://doi.org/10.3390/tropicalmed3030076 (registering DOI) -
Abstract
Parasites have threatened Australia’s biosecurity since the early days of European settlement. Tick fever in cattle and liver fluke, along with their invertebrate hosts, and hydatid disease head the list of parasites that are still impacting livestock industries. In addition, there are many
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Parasites have threatened Australia’s biosecurity since the early days of European settlement. Tick fever in cattle and liver fluke, along with their invertebrate hosts, and hydatid disease head the list of parasites that are still impacting livestock industries. In addition, there are many parasites that have been introduced that are of significance to public health as well as the conservation of native wildlife. As a consequence of these early arrivals, Australia has become much more aware of its vulnerability should parasites such as Trichinella and Trypanosoma evansi become established in Australia. However, recent discoveries concerning Leishmania and other trypanosomes have demonstrated that Australia must not become complacent and reliant on dogma when considering the potential emergence of new threats to its biosecurity. In this short review, the major parasite threats to Australia’s biosecurity are summarised, some misconceptions are emphasised, and attention is given to the importance of challenging dogma in the face of a dearth of information about Australian native fauna. Full article
Open AccessCommunication
Balance and Gait of Frail, Pre-Frail, and Robust Older Hispanics
Geriatrics 2018, 3(3), 42; https://doi.org/10.3390/geriatrics3030042 (registering DOI) -
Abstract
Older Hispanics are an understudied minority group in the US, and further understanding of the association between frailty, gait and balance impairments in disadvantaged older Hispanics is needed. The objectives of this study were to compare the balance and gait of older Hispanics
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Older Hispanics are an understudied minority group in the US, and further understanding of the association between frailty, gait and balance impairments in disadvantaged older Hispanics is needed. The objectives of this study were to compare the balance and gait of older Hispanics by their frailty status. Sixty-three older Hispanics (21 men, 42 women, mean age 75 ± 7 years) attending senior centers in disadvantaged neighborhoods were grouped by their frailty status and completed balance and walking tests at a preferred speed and during street crossing simulations. Sixteen percent (n = 10) of the participants were frail, 71% (n = 45) were pre-frail, and 13% (n = 8) were robust. Frail participants had poorer balance than robust participants (F = 3.5, p = 0.042). The preferred walking speed of frail and pre-frail participants was lower (F = 6.3, p < 0.011) and they took shorter steps (F > 3.5, p = 0.002) than robust participants. During street crossing conditions, frail participants had wider steps (F = 3.3, p = 0.040), while pre-frail participants walked slower (F = 3.6, p = 0.032), and both took shorter steps than robust participants (F > 3.5, p < 0.043). Frailty and pre-frailty were prevalent and associated with gait and balance impairments in disadvantaged older Hispanics. The findings can inform the development of programs and interventions targeting this vulnerable underserved population. Full article
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Open AccessArticle
Analysing the Potential of OpenStreetMap Data to Improve the Accuracy of SRTM 30 DEM on Derived Basin Delineation, Slope, and Drainage Networks
Hydrology 2018, 5(3), 34; https://doi.org/10.3390/hydrology5030034 (registering DOI) -
Abstract
Terrain slope and drainage networks are useful components to the basins morphometric characterization as well as to hydrologic modelling. One way to obtain the slope, drainage networks, and basins delineation is by their extraction from Digital Elevation Models (DEMs) and, therefore, their accuracy
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Terrain slope and drainage networks are useful components to the basins morphometric characterization as well as to hydrologic modelling. One way to obtain the slope, drainage networks, and basins delineation is by their extraction from Digital Elevation Models (DEMs) and, therefore, their accuracy depends on the accuracy of the used DEM. Regional DEMs with high detail and accuracy are produced in many countries by National Mapping Agencies (NMA). However, the use of these products usually has associated costs. An alternative to those DEMs are the Global Digital Elevation Models (GDEMs) that can be accessed freely and cover almost the entire surface of the world. However, they are not as accurate as the regional DEMs obtained with other techniques. This study intends to assess if generating new, modified DEMs using altimetric data from the original GDEMs and the watercourses available for download in the collaborative project OpenStreetMap (OSM) improves the accuracy of the rebuilt DEMs, the slope derived from them, as well as the delineation of basins and the horizontal and vertical accuracy of the extracted drainage networks. The methodology is presented and applied to a study area located in the United Kingdom. The GDEMs used are of 30 m spatial resolution from the Shuttle Radar Topography Mission (SRTM 30). The accuracy of the original data and the data obtained with the proposed methodology is compared with a reference DEM, with a spatial resolution of 50 m, and the rivers network available at the Ordnance Survey website. The results mainly show an improvement of the horizontal accuracy of the drainage networks, but also a decrease of the systematic errors of the new DEMs, the derived slope, and the vertical position of the drainage networks, as well as the basin’s identification for a set of pour points. Full article
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Open AccessFeature PaperArticle
Modeling and Optimal Design of Absorbent Enhanced Ammonia Synthesis
Processes 2018, 6(7), 91; https://doi.org/10.3390/pr6070091 (registering DOI) -
Abstract
Synthetic ammonia produced from fossil fuels is essential for agriculture. However, the emissions-intensive nature of the Haber–Bosch process, as well as a depleting supply of these fossil fuels have motivated the production of ammonia using renewable sources of energy. Small-scale, distributed processes may
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Synthetic ammonia produced from fossil fuels is essential for agriculture. However, the emissions-intensive nature of the Haber–Bosch process, as well as a depleting supply of these fossil fuels have motivated the production of ammonia using renewable sources of energy. Small-scale, distributed processes may better enable the use of renewables, but also result in a loss of economies of scale, so the high capital cost of the Haber–Bosch process may inhibit this paradigm shift. A process that operates at lower pressure and uses absorption rather than condensation to remove ammonia from unreacted nitrogen and hydrogen has been proposed as an alternative. In this work, a dynamic model of this absorbent-enhanced process is proposed and implemented in gPROMS ModelBuilder. This dynamic model is used to determine optimal designs of this process that minimize the 20-year net present cost at small scales of 100 kg/h to 10,000 kg/h when powered by wind energy. The capital cost of this process scales with a 0.77 capacity exponent, and at production scales below 6075 kg/h, it is less expensive than the conventional Haber–Bosch process. Full article
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Open AccessArticle
Financial Big Data Solutions for State Space Panel Regression in Interest Rate Dynamics
Econometrics 2018, 6(3), 34; https://doi.org/10.3390/econometrics6030034 (registering DOI) -
Abstract
A novel class of dimension reduction methods is combined with a stochastic multi-factor panel regression-based state-space model in order to model the dynamics of yield curves whilst incorporating regression factors. This is achieved via Probabilistic Principal Component Analysis (PPCA) in which new statistically-robust
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A novel class of dimension reduction methods is combined with a stochastic multi-factor panel regression-based state-space model in order to model the dynamics of yield curves whilst incorporating regression factors. This is achieved via Probabilistic Principal Component Analysis (PPCA) in which new statistically-robust variants are derived also treating missing data. We embed the rank reduced feature extractions into a stochastic representation for state-space models for yield curve dynamics and compare the results to classical multi-factor dynamic Nelson–Siegel state-space models. This leads to important new representations of yield curve models that can be practically important for addressing questions of financial stress testing and monetary policy interventions, which can incorporate efficiently financial big data. We illustrate our results on various financial and macroeconomic datasets from the Euro Zone and international market. Full article

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