Competition and unitization in oil extraction : a tale of two tragedies

This paper compares two organizational modes for extracting oil from a common pool: unitization and competitive extraction. The analysis suggests that the general presumption that unitization is surplus enhancing relative to competitive extraction may not always be valid due to contractual incompleteness associated with unitization contracts. While competitive extraction suffers from the tragedy of the commons, unitization can be subject to the dual tragedy of the anticommons. This provides an explanation for the puzzle confronting the oil industry that firms are often reluctant to voluntarily enter unitization agreements.

Changes in oil content, lipid class and fatty acid composition of the microalga Chaetoceros calcitrans over different phases of batch culture

 Abstract
The diatom Chaetoceros calcitrans is a microalgal species used as food for larva in aquaculture for many species worldwide. Chaetoceros calcitrans is an important source of omega 3 long chain (C ≥ 20) polyunsaturated fatty acids (n-3 LC PUFA), chiefly eicosapentaenoic acid (EPA, 20:5n-3). This article reports lipid content, lipid class composition and fatty acid profiles of each lipid class during the growth cycle of batch cultures of C. calcitrans. Total lipid content and the concentration of neutral lipid were highest in the late stationary growth phase (day 12). However, the amount of EPA was highest during the logarithmic growth phase (1.24 pg/cell on day 4). EPA was initially concentrated in the glycolipid fraction, but this fraction decreased during logarithmic growth, coinciding with the increase in neutral lipid. Docosahexaenoic acid (22:6n-3, DHA) (0.91 pg/cell) was reported as a major fatty acid (>10 mg/100 g) in all lipid classes on day 1. DHA was depleted quickly from the neutral lipid and glycolipid classes, but at a slower rate from the polar lipid fraction. This work confirms that C. calcitrans is a good source of lipid, in particular EPA, for larval and adult filter feeders in aquaculture.

Ionic liquid adsorption and nanotribology at the silica-oil interface: hundred-fold dilution in oil lubricates as effectively as the pure ionic liquid

The remarkable physical properties of ionic liquids (ILs) make them potentially excellent lubricants. One of the challenges for using ILs as lubricants is their high cost. In this article, atomic force microscopy (AFM) nanotribology measurements reveal that a 1 mol % solution of IL dissolved in an oil lubricates the silica surface as effectively as the pure IL. The adsorption isotherm shows that the IL surface excess need only be approximately half of the saturation value to prevent surface contact and effectively lubricate the sliding surfaces. Using ILs in this way makes them viable for large-scale applications.

High-efficient production of boron nitride nanosheets via an optimized ball milling process for lubrication in oil

Although tailored wet ball milling can be an efficient method to produce a large quantity of two-dimensional nanomaterials, such as boron nitride (BN) nanosheets, milling parameters including milling speed, ball-to-powder ratio, milling ball size and milling agent, are important for optimization of exfoliation efficiency and production yield. In this report, we systematically investigate the effects of different milling parameters on the production of BN nanosheets with benzyl benzoate being used as the milling agent. It is found that small balls of 0.1-0.2 mm in diameter are much more effective in exfoliating BN particles to BN nanosheets. Under the optimum condition, the production yield can be as high as 13.8% and the BN nanosheets are 0.5-1.5 μm in diameter and a few nanometers thick and of relative high crystallinity and chemical purity. The lubrication properties of the BN nanosheets in base oil have also been studied. The tribological tests show that the BN nanosheets can greatly reduce the friction coefficient and wear scar diameter of the base oil.

Fabrication of superhydrophobic surfaces by smoke deposition and application in oil-water separation

 Utilizing the smoke emitted by discarded silicone combustion, a simple method of smoke deposition is presented for fabricating a superhydrophobic surface with outstanding water repellence, which exhibited a water contact angle of 164 ± 0.8° and a sliding angle of lower than 1°. In addition, the as-prepared surface possesses favourable heat, water impact and water immersion stabilities. Oil leakages seriously endanger both the environment and the social economy. By this simple smoke deposition method, a selective-wettability copper mesh has been fabricated to separate oil-water mixtures. The smoke-deposited mesh achieved a high separation efficiency of over 93% for various oils, and showed excellent reusability, maintaining a high separation efficiency over 10 cycles. The water repellence of the used mesh can be refreshed by recoating with silicone and smoke deposition. This work provides a new strategy to utilize discarded silicone to fabricate superhydrophobic surfaces and oil-water separation meshes.

Formulation of monodisperse water-in-oil emulsions encapsulating calcium ascorbate and ascorbic acid 2-glucoside by microchannel emulsification

The aim of this study was to investigate the effects of the emulsifying conditions and emulsifier type on production of water-in-oil (W/O) emulsions encapsulating ascorbic acid derivatives by microchannel (MC) emulsification. The ascorbic acid derivatives added in a dispersed aqueous phase are calcium ascorbate (AA-Ca) and ascorbic acid 2-glucoside (AA-2G). The continuous phase used was decane, soybean oil or their mixture, containing 5% (w/w) tetraglycerin monolaurate condensed ricinoleic acid ester or sorbitan trioleate. A hydrophobized silicon MC array plate (model: MS407) with a channel depth of 7μm was used for MC emulsification. The use of MC emulsification enabled successful encapsulation of AA-Ca and AA-2G in monodisperse W/O emulsion droplets with coefficients of variation (CV) less than 7%. Their average droplet diameter (dav) increased with increasing the continuous-phase viscosity that is similar or higher than the dispersed-phase viscosity. The dav and CV of the resultant monodisperse W/O emulsions were unaffected by the dispersed-phase flow rate below critical values of 1.2-1.6mLh-1 when using decane as the continuous-phase medium.

Preparation and characterization of water-in-oil-in-water emulsions containing a high concentration of L-ascorbic acid

This study sought to encapsulate a high concentration of L-ascorbic acid, up to 30% (w/v), in the inner aqueous phase of water-in-oil-water (W/O/W) emulsions with soybean oil as the oil phase. Two-step homogenization was conducted to prepare W/O/W emulsions stabilized by a hydrophobic emulsifier and 30% (v/v) of W/O droplets stabilized by a hydrophilic emulsifier. First-step homogenization prepared W/O emulsions with an average aqueous droplet diameter of 2.0 to 3.0 μm. Second-step homogenization prepared W/O/W emulsions with an average W/O droplet diameter of 14 to 18 μm and coefficients of variation (CVs) of 18% to 25%. The results indicated that stable W/O/W emulsions containing a high concentration of L-ascorbic acid were obtained by adding gelatin and magnesium sulfate in the inner aqueous phase and glucose in both aqueous phases. L-Ascorbic acid retention in the W/O/W emulsions was 40% on day 30 and followed first-order kinetics.

Preparation and characterization of water-in-oil emulsions loaded with high concentration of l-ascorbic acid

The present study was conducted to encapsulate higher concentration of l-ascorbic acid up to (30 g 100 mL-1) in the dispersed phase of water-in-oil (W/O) emulsions. Their continuous phase contained refined soybean oil or Moringa oleifera oil and a food-grade hydrophobic emulsifier. The volume fraction of the dispersed phase was fixed as to 30%. W/O emulsions with l-ascorbic acid retention greater than 95% were prepared using rotor-stator homogenizer at 7000 rpm for 5 min. The prepared W/O emulsions under this operating conditions had average droplet diameter of 2.0-3.0 μm and coefficients of variation of 13%-22%. All the W/O emulsions were stable for more than 30 days at 4 °C or 25 °C with slight increase in average droplet diameter and without phase separation. Their l-ascorbic acid retentions were 50 g 100 g-1 at 4 °C and 30 g 100 g-1 at 25 °C after 30 days of storage. l-ascorbic acid retention ratio of the prepared W/O emulsions followed first-order kinetics with a good fit.

Polymer organogels stabilized HIPE organogels and applications in oil fields

This research focuses on polymer stabilized high internal phase emulsions for oil spill recovery and oil safety.

In situ synchrotron SAXS study of polymerizable microemulsions

We present for the first time a real-time small-angle X-ray scattering (SAXS) study of the structural transition of fluid microemulsion to solid polymerized material in a silicone polymerizable microemulsion system. A reactive methacrylate-terminated siloxane macromonomer (MTSM, Mn ∼ 1000 g/mol) was synthesized and used for microemulsion formulations comprising MTSM (oil phase), water, and a mixture of nonionic surfactant (Teric G9A8) with isopropanol. In situ synchrotron SAXS was used to investigate time-dependent nanostructure evolution during the polymerization reaction, which was directly initiated by X-ray radiation. The SAXS data were analyzed using both the Teubner-Strey model and the core-shell model. The results obtained by the Teubner-Strey model showed that the domain size (d) decreased while the correlation length (ξ) increased upon polymerization. The analysis in terms of the core-shell model displayed that adding water to the precursor microemulsion caused the water droplets to start swelling, which resulted in the discontinuity of water in oil microemulsion. There exhibited large differences in morphologies of polymerized materials from the microemulsion formulations with different water and surfactant contents. The core and shell sizes of water droplets decreased during the course of polymerization when there was 15 wt % or more water in the microemulsion formulation; the polymerized material thus exhibited increasingly discrete granular morphology. When there was 10 wt % or less water content in the precursor microemulsion, the rearrangement of water domains could be minimized during the course of polymerization and transparent polymerized material was obtained.

The concentration of oleocanthal in olive oil waste

The aim of this study was to determine the concentration of oleocanthal in olive pomace waste and compare this to its concentration in extra-virgin olive oil (EVOO). The concentration of oleocanthal in freshly pressed EVOO and its subsequent waste was analysed at early, mid and late season harvests. Oleocanthal concentrations were quantified using high-performance liquid chromatography–mass spectrometry. In oil, oleocanthal concentration was as follows: 123.24 ± 6.48 mg kg¯¹1 in early harvest, 114.20 ± 17.42 mg kg¯¹ in mid harvest and 152.22 ± 10.54 mg kg¯¹ in late harvest. Its concentration in waste was determined to be: 128.25 ± 11.33 mg kg¯¹ in early harvest, 112.15 ± 1.51mg kg¯¹ in mid harvest and 62.35 ± 8.00 mg kg¯¹ in late harvest. Overall, olive pomace waste is a valuable source of oleocanthal.

Exploring the oil price and real GDP nexus for a small island economy, the Fiji Islands

The goal of this paper is to examine the relationship between real GDP and oil prices using time series data for the period 1970–2005. Our main finding is that an increase in oil has a positive, albeit inelastic, impact on real GDP, inconsistent with the bulk of the literature. We argue that this is not a surprising result for the Fiji Islands. Our central argument focuses on two aspects of the Fijian economy: (1) the fact that actual output in Fiji has been around 50 per cent less than potential output; thus, Fiji's actual output has not reached a threshold level at which oil prices can negatively impact output; and (2) a rise in oil prices filters through to value added, which in turn is reflected in a larger actual output.

Understanding the oil price-exchange rate nexus for the Fiji Islands

In this paper, we examine the relationship between oil price and the Fiji–US exchange rate using daily data for the period 2000–2006. We use the generalised autoregressive conditional heteroskedasticity (GARCH) and exponential GARCH (EGARCH) models to estimate the impact of oil price on the nominal exchange rate. We find that a rise in oil prices leads to an appreciation of the Fijian dollar vis-à-vis the US dollar.