POLYMER SOLUBILITY THEORY PREDICTS EFFICIENCY OF RESIDUAL OIL EXTRACTION BY POLAR SOLVENTS

ABSTRACT

Light paraffinic solvents (C2 to C7) have traditionally been utilized by the petroleum refining industry to extract oils from crude distillation residua. Extracted oils constitute feedstock to lubricants manufacture and, to a lesser extent, additional cracking stock. More recent literature reveals a growing interest in polar, non-hydrocarbon partially oil-soluble solvents such as alcohols, ketones, and esters of lower carboxylic acids. In this work, articles and patents which report the separation of residua into asphalt and extracted oil by means of polar solvents are briefly reviewed, and the separation performance of same of those solvents is correlated to the solute-solvent interaction parameter (?) in the Flory-Huggins theory of polymer solubility. The three dimensional solubility parameter (δ) approach is followed to estimate ? for the solvents of interest at the appropriate operating conditions. The saturate, aromatic, and polar compounds fractions of a bitumen are characterized by solubility parameters equal to the values of δ of the solvents or mixtures thereof used by the standard ASTM D-2007 chromatographic fractionation of the deasphaltenated oil (DAO). A mean value of ? is found for every DAO-solvent pair, treatment ratio and temperature. For each solvent considered, yields of extracted oil at varying operating conditions (temperature, pressure, solvent /feed ratio) are found to be well correlated to ?, in according with theoretical predictions that the lower a value of ? a solvent has for a given solute, the better it dissolves the solute and the higher the yield.

It is suggested that this type of approach could supply criteria to select solvents and operating conditions for applications requiring high yields (to produce additional cracking stock) or lower yields but high rejection of metals and heteroatoms (e.g. for lube oil bases extraction).     

The importance of vegetables in ensuring both food and nutritional security in attainment of the Millennium Development Goals

A nutritious and varied diet is a critical means by which good health can be maintained. Consumption of less than 200 g of vegetables per person per day in many countries today is common and this low amount, often in conjunction with poverty and poor medical services, is associated with unacceptable levels of mortality and malnutrition in preschool children and other vulnerable groups. An increase in the availability, affordability and consumption of nutrient-dense vegetables and pulses is one way malnutrition may be substantially reversed—yet nutritional security appears to be less valued than food security by key decision makers, and vegetable crops thus receive inadequate research investment. Opportunities exist for the poor to improve their access to vegetables, particularly if they are willing to grow home gardens. Research continues on defining appropriate nutrient-dense vegetables for such activities, but these efforts may be compromised by failure to adopt good agricultural practices, resulting in contamination and unhealthy produce for producers and consumers. The scientific community is ready to play its role in battling malnutrition and hunger, but unless the political resolve can be found to support the causes of both food and nutritional security together, it is unlikely that the Millennium Development Goals will be achieved in a timely fashion. Redressing the current imbalance in agricultural investment can improve efficiency in food production and ensure nutritious diets can be a reality for all people.     

Effects of Retail Style or Food Service Style Packaging Type and Storage Time on Sensory Characteristics of Bacon Manufactured from Commercially Sourced Pork Bellies

Objectives were to characterize differences in pork bellies that were stored frozen for different durations prior to processing and characterize sensory properties of the bacon derived from those bellies when stored in either retail or food service style packaging. Bellies (n = 102) were collected from 4 different time periods, fresh bellies (never frozen) and bellies frozen for 2, 5, or 7 mo, and manufactured into bacon under commercial conditions. Food service bacon was packaged in oxygen‐permeable polyvinyl lined boxes layered on wax‐covered lined paper and blast frozen (–33 °C) for 45 or 90 d after slicing. Retail bacon was vacuum‐packaged in retail packages and refrigerated (2 °C) in the dark for 60 or 120 d after slicing. At the end of respective storage times after slicing, bacon was analyzed for sensory attributes and lipid oxidation. Off‐flavor and oxidized odor of bacon increased (P < 0.01) with increasing storage time in both packaging types. Lipid oxidation increased (P < 0.01) as storage time increased from day 0 to day 45 in food service packaged bacon from frozen bellies, but was unchanged (P ≥ 0.07) with time in food service packaged bacon from fresh bellies. Lipid oxidation was also unchanged (P ≥ 0.21) over time in retail packaged bacon, with the exception of bellies frozen for 5 mo, which was increased from day 0 to day 90. Overall, off‐flavor, oxidized odor, and lipid oxidation increased as storage time after processing increased. Freezing bellies before processing may exacerbate lipid oxidation as storage time after processing was extended.     

Quantification of aortic stenosis in mechanically ventilated patients using multiplane transesophageal Doppler echocardiography

OBJECTIVE: The development of sudden postoperative hearing loss as a complication of microvascular decompression (MVD) operations in the cerebellopontine angle has already been reported. A sudden hearing loss of vascular origin may also occur hours or days after such operations, but even in such cases an improvement of hearing over the following weeks is possible. Here we report on a gradual deterioration of hearing over a period of two weeks after MVD which has not been described in the literature up to now. CLINICAL PRESENTATION: A MVD operation was performed twice on a 36 year old patient with trigeminal neuralgia. After the second operation the patient developed a slight hearing impairment 3 days postoperatively which increased over a period of two weeks and ended up with total deafness. The course of intra-operative brainstem auditory evoked potentials and postoperative audiograms is documented. CONCLUSION: Because of gradual development of the delayed hearing loss, we conclude that postoperative tissue scarring may be the underlying pathology.     

Effect of fibre morphology on flocculation of fibre–cement suspensions

The objective of the present research was to evaluate the effect of fibre morphology (e.g., length, width, fibrillation, broken ends, content of fines and number of fibres per gram) on flocculation and drainage properties of fibre–cement suspensions and on physical properties of the fibre–cement composites. Mechanical refining was used to change the morphological properties of Eucalyptus and Pinus pulps. Results show that the mechanical refining increased the size of the formed flocs and decreased the concentration of free small particles (with dimensions between 1 and 20 µm) as a consequence of the increased fibrillation and content of fines, which increased the capacity of the fibres to capture the mineral particles. High levels of refining were necessary for Pinus pulp to obtain cement retention values similar to those obtained by unrefined Eucalyptus pulp. This is due to the higher number of fibres per gram in Eucalyptus pulp than in Pinus pulp. Pulp refining improved the packing of the particles and, although decreased the drainage rate, it contributed to a less porous structure, which improved the microstructure of the composite.     

An Electrometer Amplifier with Low Input Capacitance and Large Input Dynamic Range

An electrometer amplifier has been designed for biological research with the following data: input resistance larger than 1012; input current 10-12 A; low input capacitance; and an input dynamic range from 0 to ± 7 v. The input stage consists of JFET.     

Counterconditioning of an overshadowed cue attenuates overshadowing.

In 3 Pavlovian conditioned lick-suppression experiments, rats received overshadowing treatment with a footshock unconditioned stimulus such that Conditioned Stimulus (CS) A overshadowed CS X. Subjects that subsequently received CS X paired with an established signal for saccharin (CS B) exhibited less overshadowing of the X–footshock association than subjects that did not receive the X–B pairings (Experiment 1). Experiment 2 replicated this effect and controlled for some additional alternative accounts of the phenomenon. In Experiment 3, this recovery from overshadowing produced by counterconditioning CS X was attenuated if CS B was massively extinguished prior to counterconditioning. These results are more compatible with models of cue competition that emphasize differences in the expression of associations than those that emphasize differences in associative acquisition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Weathering of vegetable fibre-clinker free cement composites

Ground iron blast-furnace slag (BFS) activated by a mixture of gypsum and hydrated lime was examined as an alternative binder for fibre-cement mortars produced by a low energy consumption method. Brazilian fibrous wastes from sisal and banana crops and also from a eucalyptus pulp mill were chosen for reinforcement. The composite preparation followed conventional mixing, ordinary vibration and wet chamber curing for the seven initial days. The composites achieved a modulus of rupture of up to 3.92 MPa at an age of 28 days. Flexural toughness was at least 40% superior to that of the non-reinforced matrix. Microstructure analyses presented additional information on the understanding of fibre-matrix interaction and its correlation with composites macrostructural behaviour. The effects of natural weathering on the performance of fibre-cement composites were investigated in comparison with accelerated ageing tests. Sixteen months of exposure in tropical climate conditions caused the severest decay in the loading capacity and composite embrittlement, in spite of the absence of superficial darkening or visible cracks. The reduction of the mechanical properties was attributed to a combination of different processes, such as matrix carbonation, fibre mineralization and transition zone degeneration.

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Résumé Les laitiers de haut foumeau broyés et activés par un mélange de phosphogypse et de chaux hydratée ont été examinés comme un liant alternatif pour des mortiers en fibre-ciment produits par une méthode de basse consommation d'énergie. Des déchets, tels que les fibres de récoltes du sisal et de la banane et aussi ceux de la pate à papier d'eucalyptus, ont été choisis comme renforcement. Le mélange du composite a suivi le processus conventionnel de malaxage, vibration et cure en chambre humide pendant sept jours. Les composites ont présenté des modules de rupture jusqu'à 3,92 MPa après 28 jours. La tenacité en flexion a été au moins 40% supérieure à celle de la matrice non renforcée. Une analyse de la microstructure a exposé des informations supplémentaires sur la compréhension du mécanisme d'interaction de la fibre-matrice et sa corrélation avec le comportement macrostructural des composites. Les performances des composites fibres/ciment ont été étudiées sous des conditions climatiques naturelles et par des essais de vieillissement accéléré. Le stockage du matériau sous des conditions tropicales, pendant seize mois, a provoqué les pertes les plus sévères concernant la capacité de résistance et la fragilisation du composite, malgré l'absence de noircissement superficiel ou de fissures visibles. La réduction des performances mécaniques a été attribuée à une combinaison de différents processus, comme la carbonatation de la matrice, la pétrification de la fibre et la dégénérescence de la zone de transition.