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•Capillary driven flow is a promising method to probe liquids’ rheology in nanofluidic systems.•Continuous change in the advancing contact angle of diluted bitumen is responsible for ...theoretical model failure to describe the experimental results.•A theoretical model is developed to capture capillary filling of non-Newtonian Bingham fluid in the nanochanenl.•In the presence of Bingham yield stress, the relationship between position squared (x2) of advancing liquid and time (t) is found to be non-linear.
Observations of capillary-driven flow of a liquid in a nanochannel can be used to study the liquid’s rheology. Capillary-driven flow of several pure liquids and bitumen diluted in Heptol (80:20) were studied using a nanofluidic chip. Filling speed of water was lower than the theoretical predictions, as expected. However, for methanol and ethanol, experimental values agreed well with theoretical predictions. 5 and 11wt.% bitumen solutions in heptol (80:20) followed the theoretical predictions quite well at the initial times but demonstrated deviation for longer penetration times. However, for 20 and 40wt.% diluted bitumen, experimental observations significantly deviated from the theoretical models. Those deviations were related to the continuous changes in the observed dynamic contact angle of the advancing meniscus. Nanochannel blockage has frequently occurred due to the presence of asphaltenes aggregates when 20wt.% diluted bitumen was used. Theoretical model for capillary filling of Bingham Plastic fluid was developed to probe the possible non-Newtonian behavior of diluted bitumen above the onset of asphaltenes precipitation. Given very small yield stress, it was difficult to precisely distinguish between Newtonian and non-Newtonian Bingham Plastic behavior. Nevertheless, our results show that Bingham Plastic model can describe the rheology of 5wt.% and 11wt.% bitumen at nanoscale more accurately than the Newtonian model. Our study shows nanochannels provide an experimental platform to analyze the flow of petroleum in the nanoporous media.
After successful isolation of the most interfacially active subfraction of asphaltenes (IAAs) reported in the first part of this series of publications, comprehensive chemical analyses including ...ES-MS, elemental analysis, Fourier transform infrared (FTIR) spectroscopy, and nuclear magnetic resonance (NMR) spectrometry were used to determine how the molecular fingerprint features of IAAs are different from those of the remaining asphaltenes (RAs). Compared with the RAs, the IAA molecules were shown to have higher molecular weight and higher contents of heteroatoms (e.g., three times higher oxygen content). The analysis on the elemental content and FTIR spectroscopy suggested that IAAs contained higher contents of high-polarity sulfoxide groups than the RAs. The results of ES-MS, NMR, FTIR, and elemental analyses were used to construct average molecular representations of IAA and RA molecules. These structures were used in molecular dynamics (MD) simulation to study interfacial and aggregation behaviors of the proposed molecules. The MD simulation study showed little affinity of representative RA molecules to the oil/water interface, while the representative IAA molecules had much higher interfacial activity, reflecting the extraction method. The aggregation of IAA molecules in the bulk oil phase and their adsorption at oil/water interface were not directly related to the ring system, but rather to the associations between or including sulfoxide groups. During the simulation, the IAA molecules were found to be self-assembled in solvent, forming supramolecular structures and a porous network at the oil/water interface, as suggested in our previous work. The results obtained in this study provide a better understanding of the role of asphaltenes in stabilizing petroleum emulsions.
A polar plunge is a term referring to an ice-cold water immersion (CWI), usually in the winter period. It is also a part of a specific training program (STP) which currently gains popularity ...worldwide and was proven to display paradigm-shifting characteristics. The aim of this study was to compare the indices of mental functioning (including depression, anxiety, mindfulness) and duration of upper respiratory tract infection (URTI) measured among the study participants. A set of questionnaires was distributed via the Internet. Participants declaring regular STP practice were selected (
= 77). Two groups were matched based on a case-control principle: the first one (the control group) comprised participants who did not declare nor CWI practice, nor STP practice. The second one comprised participants declaring regular CWI practice only. The CWI only group displayed better mental health indices and shorter URTIs compared to the control group. Moreover, the STP group also displayed better general mental health, less somatic complaints, and shorter URTIs compared to the CWI only group. This study suggests the existence of CWI's potential in boosting mental health and immune system functioning, however when complemented by a specific breathwork, this potential can be increased. However, further research is required.
Physical properties of interfacial layers formed at the xylene–water interface by the adsorption of a polyaromatic organic compound, N-(1-hexylheptyl)-N′-(5-carbonylicpentyl) ...perylene-3,4,9,10-tetracarboxylic bisimide (in brief, C5Pe), were studied systematically. The deprotonation of the carboxylic group of C5Pe at alkaline pH made it highly interfacially active, significantly reducing the xylene–water interfacial tension. Thin liquid film experiments showed a continuous buildup of heterogeneous C5Pe interfacial layers at the xylene–water interfaces, which contributed to the formation of stable W/O emulsions. Continual accumulation and rearrangement of C5Pe aggregates at the xylene–water interface to form a thick layer was confirmed by in situ Brewster angle microscopy (BAM) and atomic force microscopy (AFM). The rheology measurement of the interfacial layer by double-wall ring interfacial rheometry under oscillatory shear showed that the interfacial layers formed from C5Pe solutions of high concentrations were substantially more elastic and rigid. The presence of elastically dominant interfacial layers of C5Pe led to the formation of stable water-in-xylene emulsions.
Conventional wisdom says that asphaltene adsorption at the water−oil interface is the main source of high stability of W/O emulsions in petroleum systems. Although this approach is partiallly ...correct, it does not explain all experimental data. High-resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry data show that the composition of the surface material collected from emulsified water droplets is different from asphaltenes, resins, and the parent oil. Microscopic observations show that material formed at the oil−water boundary often exhibits optical anisotropy, suggesting molecular organization of the surface phase. Although we still do not have a clear picture of W/O petroleum emulsion stabilization, the existing conventional paradigm is such a gross generalization that, in our opinion, it is impeding rather than aiding our progress in understanding the stabilization mechanisms involved in petroleum emulsion systems.
Metabolic Pathway Mining Czarnecki, Jan M; Shepherd, Adrian J
Methods in molecular biology (Clifton, N.J.),
2017, Letnik:
1526
Journal Article
Understanding metabolic pathways is one of the most important fields in bioscience in the post-genomic era, but curating metabolic pathways requires considerable man-power. As such there is a lack of ...reliable, experimentally verified metabolic pathways in databases and databases are forced to predict all but the most immediately useful pathways.Text-mining has the potential to solve this problem, but while sophisticated text-mining methods have been developed to assist the curation of many types of biomedical networks, such as protein-protein interaction networks, the mining of metabolic pathways from the literature has been largely neglected by the text-mining community. In this chapter we describe a pipeline for the extraction of metabolic pathways built on freely available open-source components and a heuristic metabolic reaction extraction algorithm.
Electrohydrodynamic instabilities were induced in thin water-in-oil emulsion films by application of external DC electric field. The dominant wavelengths of instabilities were measured for constant ...electric fields of various strengths. The dominant wavelengths agreed reasonably well with theoretical predictions based on a linear stability model. The linear stability model used in this study took into account experimentally measured repulsive disjoining pressure and calculated Maxwell stress. The observation of such instabilities can help to understand the rupture mechanism of emulsion films under the influence of electric field.
An electrophoresis technique is used to measure the zeta potential of fine bubbles dispersed in aqueous solutions. An improved apparatus of a microelectrophoretic type is developed for the bubble ...zeta potential measurements. Electrodes for generating either oxygen or hydrogen gas bubbles are designed in such a manner that micrometer-sized bubbles can be produced over the entire cross section of the electrophoresis cell. Consequently, a bubble can be easily selected at the so-called stationary plane, where bubble electrophoresis measurements are conducted. Furthermore, a motorized vertical translation stage controlled by computer is implemented. When bubbles rise due to buoyancy, the electrophoresis cell mounted on the translation stage is made to move downward so that the bubbles can be kept in the field of view of the microscope. As a result, the movement of bubbles with diameters up to 80 μm can be readily followed and bubble trajectory can be traced for 4–8 s. Effects of water chemistry—pH concentration and type of metal ions—on the bubble zeta potential were studied. The experimental results generated for bubble zeta potential are consistent with data available in the literature.
Increasingly biological text mining research is focusing on the extraction of complex relationships relevant to the construction and curation of biological networks and pathways. However, one ...important category of pathway - metabolic pathways - has been largely neglected.Here we present a relatively simple method for extracting metabolic reaction information from free text that scores different permutations of assigned entities (enzymes and metabolites) within a given sentence based on the presence and location of stemmed keywords. This method extends an approach that has proved effective in the context of the extraction of protein-protein interactions.
When evaluated on a set of manually-curated metabolic pathways using standard performance criteria, our method performs surprisingly well. Precision and recall rates are comparable to those previously achieved for the well-known protein-protein interaction extraction task.
We conclude that automated metabolic pathway construction is more tractable than has often been assumed, and that (as in the case of protein-protein interaction extraction) relatively simple text-mining approaches can prove surprisingly effective. It is hoped that these results will provide an impetus to further research and act as a useful benchmark for judging the performance of more sophisticated methods that are yet to be developed.
Microfluidics-based lab-on-a-chip systems have shown great promise for characterization of heavy oil and its fractions. Asphaltenes, comprising the heaviest and most complex fraction of heavy oil, ...are known for their strong tendency for aggregation and causing severe problems in the production and transportation of heavy oil. Asphaltenes are also shown to play a key role in stabilization of water-in-crude oil (W/CO) emulsions and significantly impact the rheological properties of crude oil. Therefore, this Review highlights the recent progress made by micro-/nanofluidic technologies to understand the asphaltenes’ phase behavior, including solubility, aggregation/precipitation, and deposition at the micro-/nanoscale. The application of these miniaturized systems in the study of W/CO emulsions and the coalescence kinetics of emulsified water droplets are also reviewed herein. Additionally, recent developments on understanding the heavy oil rheology (in the absence and presence of asphaltenes) in the micro- and nanoconfinement in combination with theoretical predictions are presented in this study. Finally, some ideas and recommendations for future research directions on asphaltene-related problems using micro-/nanofluidic systems are highlighted.
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