Differences In Viscosity Research Articles

The fabrication of porous hollow polysulfone microspheres with PEG as a porogen for methylene blue adsorption

A porous hollow polysulfone (donated as PHPSF) microspheres were prepared by non-solvent-induced phase separation using PEG as a porogen. The influence of the molecular weights (Mw) of PEG on the morphology and porous structure of the microspheres were investigated. As the Mw of PEG increasing from 600 to 10,000 g·mol–1, the viscosity of the system increases, leading to the increase of the viscosity difference between the dispersed phase and the continuous phase, and a delay in phase separation. Hence, the diameter and shell thickness of the obtained microspheres increase with the porosity reducing. Moreover, when the Mw of PEG is below 4000, the low |Δδ| between PEG and solvent is conducive to the formation of microporous structure with narrow pore distribution. The as-prepared PHPSF microspheres exhibit a separation efficiency of 6 times for MB than that of the original PSF microspheres. In addition, a reusability of 5 times of PHPSF is achieved even in the harsh acid or alkali condition. These results clarify the relationship between the different Mw of PEGs and microspheres morphology. Therefore, this kind of PHPSF microspheres holds a promising for the water organic pollution treatment.

Numerical simulation and multi-factor optimization of hydraulic fracturing in deep naturally fractured sandstones based on response surface method

Hydraulic fracturing is an effective stimulation technology for enhancing recovery in deep reservoirs. Multi-factor analysis and fracturing design optimization are essential for the efficient development of deep naturally fractured sandstones. A three-dimensional flow-stress-damage (FSD) coupled model was presented to simulate the hydraulic fracture (HF) propagation and stimulated reservoir volume (SRV). The numerical model was validated with experimental results of the HF-natural fracture (NF) intersection. The sensitivity analysis is conducted to screen the significant factors affecting HF geometry and SRV. The response surface method was employed to investigate the coupling effects of multiple geomechanical and hydraulic factors on SRV by integrating Box-Behnken design and numerical modeling. Subsequently, the SRV was optimized by identifying the optimum combinations of uncertain parameters based on the established response surface model (RSM). The results indicated that the injection rate, NF density, fluid viscosity, and horizontal stress difference are the key factors controlling SRV. It is more difficult to improve SRV by increasing injection rate at higher horizontal stress difference than at lower horizontal stress difference. The proposed method is effective for enhancing the artificial ability to optimize the HF geometry and SRV. The results can provide insight into the fracture geometry control mechanism in deep naturally fractured sandstones, and offer a guideline for treatment design and optimization of well performance.

Institutionalized elderly are able to detect small viscosity variations in thickened water with gum-based thickeners:\xa0should texture classifications be reviewed?

BackgroundThe prevalence of dysphagia is very high in institutionalized elderly. Knowledge of the rheological and sensory characteristics of the various thickeners in elderly is limited, although it has been seen that there are differences between the rheological behaviors of gum-based thickeners with different composition. Moreover, we have not found sensory studies of viscosity in institutionalized elderly. Our hypothesis was that viscosity ranges established by the scientific societies, such as the National Dysphagia Diet Task Force (NDD), seem to be very wide and individuals might be able to detect small differences within the same texture range. The objectives of our study were 1) comparing the rheological characteristics of two commercial gum-based thickeners with different composition, dissolved in water under standard conditions, and 2) perform a sensory analysis (with both adults and institutionalized elderly) to detect different viscosities within the same texture (nectar and honey).MethodsTwo commercial thickeners based on gums (NC and RC) were studied analyzing their viscosity in water with different concentrations (shear rate: 50 s− 1; temperature: 22–25 °C). A sensory analysis involving 26 elderly and 29 adult controls was carried out to evaluate whether differences within nectar and honey textures among gum-based thickeners could be distinguished.ResultsAs the shear rate increases, viscosity decreases (non-Newtonian and pseudoplastic behavior). At the same concentration, each thickener produces a different viscosity (p < 0.05). Institutionalized elderly detected viscosity differences in nectar range of 49.9 (2.5) mPa·s (p < 0.05) and 102.2 (4.7) mPa·s (p < 0.0001). They also detected viscosity differences in honey texture range of 134.6 (9.7) mPa·s (p < 0.05) y 199.3 (9.2) mPa·s (p < 0.0001). Their caregivers also detected viscosity differences in both viscosity ranges (p < 0.0001) and with greater intensity than the elderly in honey texture (p: 0.016).ConclusionsOur results suggest that the accepted viscosity ranges by NDD for the different textures might be too wide because institutionalized elderly and their caregivers are able to discern small differences in viscosity in nectar and honey textures. Gum-based thickeners with different composition showed differences in viscosity capacity, so they are not interchangeable.

Understanding the impact of diverse structural properties of homogalacturonan rich citrus pectin-derived compounds on their emulsifying and emulsion stabilizing potential

The emulsifying and emulsion stabilizing potential of 13 citrus pectin (CP) derived samples exhibiting differences in degree of methylesterification (DM, 11–74%) and molecular weight (Mw, 2.5–151 kDa) was studied using an integrated multimethod approach, which involved the evaluation of structural and physicochemical properties of each pectin sample, as well as detailed storage stability studies of pectin-containing emulsions. It was observed that all CP derived samples had a high negative ζ-potential, depending on the DM of the sample and pH of the medium. Furthermore, they exhibited an enhanced interfacial activity at pH 6.0 compared to pH 2.5. Moreover, significant differences in viscosity were observed between CP derived samples of high (> 62 kDa) and low (< 62 kDa) Mw. A storage experiment was performed for 14 days at 4 °C to determine the physical stability of 26 oil-in-water emulsions (pH 2.5 versus 6.0) containing the CP derived pectin samples. The results revealed greater stability for high Mw (> 62 kDa) CP containing emulsions at pH 2.5, regardless pectin DM. On the contrary, flocculation and coalescence were observed at early stages in the 20 low Mw CP containing emulsions, indicating destabilization. Likewise, creaming and phase separation of the latter emulsions was evident from the day of emulsion preparation. Generally, low Mw (< 62 kDa) CP compounds performed poorly when applied as sole stabilizing compound in the emulsions.

Numerical Simulation via CFD Methods of Nitrogen Flooding in Carbonate Fractured-Vuggy Reservoirs

A reservoir-scale numerical conceptual model was established according to the actual geological characteristics of a carbonate fractured-vuggy reservoir. Considering the difference in density and viscosity of fluids under reservoir conditions, CFD (computational fluid dynamic) porous medium model was applied to simulate the process of nitrogen displacement in a fractured-vuggy reservoir after water flooding. The effects of gas injection rate, injection mode, and injector–producer location relation were studied. The results show that nitrogen flooding can yield additional oil recovery of 7–15% after water flooding. Low-speed nitrogen injection is beneficial in obtaining higher oil recovery. High speed injection can expand the sweep area, but gas channeling occurs more easily. In gas–water mixed injection mode, there is fluid disturbance in the reservoir. The gas channeling is faster in low injector–high producer mode, while the high injector–low producer mode is beneficial for increasing the gas sweep range. Nevertheless, the increment of recovery is closely related to well pattern. After nitrogen flooding, there are still a lot of remaining oil distributed in the trap area of gas cap and bottom water in the reservoir that water and gas injection can’t sweep. The establishment of the numerical conceptual model compensates for the deficiency of physical simulation research, stating that only limited parameters can be simulated during experiments, and provides theoretical bases for nitrogen flooding in fractured-vuggy reservoir.

Physical Insights about Viscosity Differences of Asphaltene Dissolved in Benzene and Xylene Isomers: Theoretical–Experimental Approaches

Physical Insights about Viscosity Differences of Asphaltene Dissolved in Benzene and Xylene Isomers: Theoretical–Experimental Approaches

Effect of polymer source variation on the properties and performance of risperidone microspheres

Owing to their inherent heterogeneity, determination of similarity of poly (lactic-co-glycolic acid) (PLGA) polymers is very challenging. The complexity in controlling PLGA characteristics has been recognized as an obstacle to the development of PLGA based long-acting complex drug products (such as microspheres). The objectives of the present study were: (1) to determine minor differences in the physicochemical characteristics (such as inherent viscosity, molecular weight (Mw), monomer ratio (L/G ratio), glass transition temperature (Tg), and blockiness) as well as in the hydrolytic degradation profiles of PLGAs from different sources; and (2) to investigate the impact of PLGAs from different sources on the properties and in vitro performance of risperidone microspheres. Four PLGA polymers were purchased from different sources with similar inherent viscosity and/or Mw, L/G ratio and end groups as per the manufacturers’ certificate of analysis (CoA). The physicochemical properties of these PLGAs were characterized using the same in-house methods and exhibited differences in inherent viscosity, Mw, blockiness and residue amount. Risperidone was chosen as the model drug and four microsphere formulations were prepared via the same solvent extraction/evaporation method using the PLGAs from different sources. The critical quality attributes of the microspheres (such as particle size, porosity and average pore diameter) and their in vitro release characteristics (burst effect and release rate) were shown to be different. A strong linear correlation was established between risperidone release and PLGA blockiness. This is the first time that such a correlation has been established, which promotes the potential need to further investigate the impact of PLGA blockiness on other PLGA based controlled release drug products.

Effect of Capsaicin Atomization-Induced Cough on Sputum Excretion in Tracheotomized Patients After Hemorrhagic Stroke: A Randomized Controlled Trial.

Background Timely and effective removal of respiratory secretions is of great significance for tracheotomized patients. The purpose of this study is to investigate the effectiveness of capsaicin nebulization to stimulate cough to promote early clearance of respiratory secretions in tracheotomized patients after hemorrhagic stroke. Method This study implemented a randomized controlled design. Sixty-three patients who were tracheotomized following a hemorrhagic stroke completed this randomized controlled trial. In the control group, 33 cases were given a routine care after tracheotomy. In the intervention group, 30 cases were given a capsaicin solution nebulization in addition to the routine care. The daily sputum output and the number of sputum suctioning were observed. The differences in sputum viscosity, cough function, and Clinical Pulmonary Infection Score (CPIS) were compared between the two groups before and after the intervention. Vital sign changes during capsaicin nebulization and suctioning were compared between the two groups in a pilot study. Results The daily sputum output of the capsaicin intervention group was significantly higher than that of the control group (p < .05). The number of sputum suctioning of capsaicin group was less than that of the control group after intervention (p < .05). The CPIS score of the capsaicin group was lower than that of the control group (p < .05) after a 1-week intervention. Patients' heart rate, respiratory rate, and oxygen saturation during capsaicin nebulization were not statistically different from those during routine sputum suctioning (p > .05). Conclusions Capsaicin atomization-induced cough can effectively promote sputum excretion of hemorrhagic stroke patients undergoing tracheotomy and has a good safety profile. The Clinical Trial registration number of this study is ChiCTR2000037772 (http://www.chictr.org.cns). Supplemental Material https://doi.org/10.23641/asha.16821352.

High-temperature ex-vessel corium spreading. Part 2: scaling principles for gravity-viscous spreading with slip at the melt–substrate interface

ABSTRACT Promoting the spreading of molten corium represents a key strategy in the dissipation of decay heat and in the maintainence of containment integrity in the aftermath of a severe nuclear accident. Precise repeatability is difficult to achieve during high-temperature melt spreading experiments, and so scaling factors are necessary to correct for differences in flow rate, viscosity, and density between comparative experiments. A gravity-viscous momentum balance derived for spreading in the two-dimensional spreading geometry employed during recent kg-scale VE-U9 experiments on ceramic and sacrificial concrete substrates establishes that no-slip spreading length scales with the square root of the mass flow rate. Scaling for the reduced mass flow rate and enhanced viscosity implied that the melt spread 37% further on the sacrificial concrete than on the inert ceramic substrate. The possibility of a lubricating film of molten concrete and ablation gases reducing friction at the lower boundary is investigated through the imposition of a slip velocity proportional to the shear at the melt–substrate interface. Simulations over a range of Navier slip lengths implied that spreading length scales with the ratio of slip length to the melt thickness and that spreading length can be augmented by as much as 68% in the case of a virtually frictionless interface.

Effect of Hydrate on Gas/Water Relative Permeability of Hydrate-Bearing Sediments: Pore-Scale Microsimulation by the Lattice Boltzmann Method

As a clean energy source with ample reserves, natural gas hydrate is studied extensively. However, the existing hydrate production from hydrate deposits faces many challenges, especially the uncertain mechanism of complex multiphase seepage in the sediments. The relative permeability of hydrate-bearing sediments is key to evaluating gas and water production. To study such permeability, a set of pore-scale microsimulations were carried out using the Lattice Boltzmann Method. To account for the differences between hydrate saturation and hydrate pore habit, we performed a gas-water multiphase flow simulation that combines the fluids’ fundamental properties (density ratio, viscosity ratio, and wettability). Results show that the Lattice Boltzmann Method simulation is valid compared to the pore network simulation and analysis models. In gas and water multiphase flow systems, the viscous coupling effect permits water molecules to block gas flow severely due to viscosity differences. In hydrate-bearing sediments, as hydrate saturation increases, the water saturation S w between the continuous and discontinuous gas phase decreases from 0.45 to 0.30 while hydrate saturation increases from 0.2 to 0.6. Besides, the residual water and gas increased, and the capillary pressure increased. Moreover, the seepage of gas and water became more tedious, resulting in decreased relative permeability. Compared with different hydrate pore habits, pore-filling thins the pores, restricting the gas flow than the grain-coating. However, hydrate pore habit barely affects water relative permeability.

Tunable thermo-sensitive electrical conductivity of melt-mixed PA- 12/PP-MWCNT nanocomposites

In this study, the correlation of morphology, temperature dependent electrical conductivity and solid-state relaxation dynamics of melt-mixed polyamide 12 (PA-12)/polypropylene-multi walled carbon nanotube (PP-MWCNT) based ternary nanocomposites has been systematically investigated. Selectively confined functionally conductive masterbatch dispersed in nylon matrix with structurally ordered co-continuous morphology enhanced the electrical conductivity due to double percolation phenomenon by virtue of their differences in melt viscosity, polarity, surface energy and similar processing window of PA-12 and PP-MWCNT. The stability of the conducting polymer nanocomposites and the correlation of temperature sensitive electrical behaviour with the endothermic transitions and dynamic-mechanical relaxation transitions in the temperature range of −20 °C–200 °C is also explored. Polymer nanocomposite based thermo-sensitive materials substantiated four distinct regimes highlighting the network build-up or restoration assisted conductivity. Our study demonstrates the tunability of temperature dependence of electrical conductivity by controlling conducting channels via manipulating the ratio of PA-12 to PP-MWCNT composite filler for temperature dependent current terminating electrical devices. The reproducibility of such temperature sensitivity has also been explored.

Molecular dynamics simulations of two-phase flow of n-alkanes with water in quartz nanopores

Nanopore networks comprising shale reservoirs exhibit special behaviors in two-phase flow. We use molecular dynamics simulations (MD) to explore the single n-alkanes (nC3-nC10)-water and mixed n-alkanes (nC3, nC6, and nC10)-water flow mechanisms in the confined nanopores of quartz. The results reveal that water molecules form four adsorbed layers near the wall, showing greater viscosity than the bulk water. For single n-alkanes cases, in the n-alkanes-water interface regions (AWIR), n-alkanes molecules tend to be parallel to the pore wall, and the tendency is more pronounced for longer n-alkanes, resulting in a decrease of AWIR width. Moreover, we observed typical liquid–liquid slip in AWIR. Ignoring the slip velocity can underestimate the flow rate of n-alkanes more than 20%. Under the driving force, the bulk n-alkanes exhibit distinct different velocity distributions due to viscosity differences. However, the total fluid velocity distributions in AWIR are quite the same, showing an apparent viscosity independent of the type of n-alkanes and pore size. For mixed n-alkanes, the velocity distribution and apparent viscosity are still the same as single n-alkanes cases due to the unchanged structure of the molecules in AWIR. Our study could provide an in-depth understanding of the oil–water two-phase flow in nanopores, especially the influence of carbon chain length on oil–water interface properties.

Creation of Liquid‐Air Dispersions in Oil and Water: Comparison of Calculations and Measurements

AbstractThe creation of liquid‐gas dispersions places very high demands on the process technology, which requires knowledge of bubble formation mechanisms. To extend the range of validity of the current calculation models to larger viscosity differences, the bubble formation mechanisms for the media combination oil/air are investigated. Compared to the media combination water/air, significant differences occur. The results obtained here will make it possible to design bubble columns in a more targeted manner in the future, which will lead to savings in resources and energy of industrial test stands.

Cost-effectiveness of agents used for evaluation of ureteral patency during intraoperative cystoscopy in gynecologic and urogynecologic surgery

Intraoperative evaluation of ureteral patency is often performed in gynecologic and urogynecologic surgery. Many agents are used to help assess the patency, each with its own associated cost, ease of use, and adverse reactions. Some agents, such as dextrose, are used as an instillation fluid to create a viscosity difference and aid the visualization of a ureteral jet. Others, such as oral phenazopyridine or the intravenous use of sodium fluorescein and indigo carmine, cause a color change of the urine to directly aid the visualization of ureteral jets. Recently, numerous studies have examined the efficacy and surgeon satisfaction of these agents. The studies have also emphasized certain options as associated with a lower cost. However, there have not been any cost studies comparing these agents. To compare the cost-effectiveness of the following 4 agents that are commonly used in assessing ureteral patency intraoperatively: oral phenazopyridine, dextrose instillation, intravenous sodium fluorescein, and intravenous indigo carmine. We constructed a decision-analytic model to compare cystoscopy using oral phenazopyridine, dextrose instillation, intravenous sodium fluorescein, and intravenous indigo carmine. Failure to see efflux resulted in work-ups for ureteral obstruction. The probabilities were obtained from published studies, and the probability of successfully seeing efflux ranged from 0.92 with oral phenazopyridine to 0.99 with intravenous indigo carmine. The costs of the agents, adverse effects, and ureteral obstruction work-ups were obtained from the University of North Carolina at Chapel Hill Department of Pharmacy, the Healthcare Cost and Utilization Project 2016 database and the FAIR Health Consumer database. The cost of a ureteral obstruction work-up used in our model ranged from $9755 for intraoperative evaluation with retrograde pyelograms and stents to $29,034 for hospitalization. Our primary outcome was the incremental cost-effectiveness ratio per unnecessary work-up for ureteral obstruction avoided. Sensitivity analyses were performed to identify the key uncertainties. Oral phenazopyridine, followed by an intravenous agent if needed, had a mean cost of $110 per patient. Dextrose averaged $151 more per patient, with only a slight improvement in avoiding unnecessary ureteral obstruction work-ups and a higher cost associated with adverse reactions (incremental cost-effectiveness ratio, $62,000). Intravenous agents cost approximately $1000 more per patient and were less effective at preventing unnecessary work-ups. Sensitivity analyses did not identify any thresholds that would significantly change the outcomes. Our model suggests that oral phenazopyridine and dextrose instillation are the least expensive and the most effective agents to aid in the visualization of ureteral patency during intraoperative cystoscopy, although dextrose is associated with higher costs owing to a higher rate of adverse reactions (primarily urinary tract infections). Intravenous sodium fluorescein and indigo carmine are historically popular first-choice agents. However, they were found to be more expensive and less effective as primary agents in our model and should likely be reserved for use as secondary agents in the event that the visualization of ureteral jets is unclear with the initial use of phenazopyridine or dextrose.

Effect of Lateral and Stress‐Dependent Viscosity Variations on GIA Induced Uplift Rates in the Amundsen Sea Embayment

AbstractAccurate glacial isostatic adjustment (GIA) models are required for correcting measurements of mass change in Antarctica and for improving knowledge of the sub‐surface, especially in areas of large current ice loss such as the Amundsen Sea Embayment (ASE). Regionally, seismic and gravity data suggests lateral differences in viscosity (3D). Furthermore, mantle flow laws allow for a stress‐dependent effective viscosity which changes over time (3D‐s). In this study we investigate whether models with 3D/3D‐s have significant effects on the uplift in the region. We use a finite element model with composite rheology consisting of diffusion and dislocation creep, forced by an ice deglaciation model starting in 1900. We use its uplift predictions as synthetic observations to test the performance of 1D model inversion in the presence of viscosity variations. Stress‐dependent rheology results in lower viscosity beneath the load and a more localized uplift pattern. We demonstrate that the background stress from earlier ice load changes can both increase or decrease the influence of stress‐induced effective viscosity changes. For the ASE, fitting 1D models to 3D model uplift results in a best fitting model with viscosity that represents the average of a large area, while for 3D‐s rheology, local viscosity is more influential. 1D models are statistically indistinguishable from 3D/3D‐s viscosity with current GPS stations. However, 3D and 3D‐s models should be taken into account when accurate uplift and gravity rate patterns are needed, as uplift can differ up to 45% compared to 1D models in between existing GPS stations.

Relationship between structure and some physico-chemical properties of funori from red seaweed Gloiopeltis

The relationship between structural characteristics and some physico-chemical properties of ma-funori and fukuro-funori was elucidated. Ma-funori and fukuro-funori were extracted from red seaweeds which was harvested in Japan. The structure of ma-funori and fukuro-funori extracted from Gloiopeltis tenax and Gloiopeltis furcata , respectively, was characterized through FT-IR and NMR spectroscopy. The assignment of signals for ma-funori showed that structure of ma-funori was relatively regular with repeating unit (1,3)-β- D -galactopyranose 6-sulfated linking to (1,4)-3,6-anhydro-α- L -galactopyranose. In contrast, the structure of fukuro-funori was complex with substitute groups such as pyruvate acetal, sulfate ester and methyl ether groups interspersing in polysaccharide chain. The physico-chemical properties of two kinds of funori which are important to restoration and conservation of artistic heritage were characterized. The solubility of fukuro-funori in water was higher than that of ma-funori. The wettability of fukuro-funori solution was better than that of ma-funori solution, whereas ma-funori solution was higher in viscosity than fukuro-funori. The structural characteristic was the main factor to determine the difference in solubility, wettability, and viscosity of two kinds of funori.

Implication of Blood Rheology and Pulmonary Hemodynamics on Exercise-Induced Hypoxemia at Sea Level and Altitude in Athletes.

This study aimed to investigate the changes in blood viscosity, pulmonary hemodynamics, nitric oxide (NO) production, and maximal oxygen uptake (V˙O2max) during a maximal incremental test conducted in normoxia and during exposure to moderate altitude (2,400m) in athletes exhibiting exercise-induced hypoxemia at sea level (EIH). Nine endurance athletes with EIH and eight without EIH (NEIH) performed a maximal incremental test under three conditions: sea level, 1 day after arrival in hypoxia, and 5 days after arrival in hypoxia (H5) at 2,400m. Gas exchange and oxygen peripheral saturation (SpO2) were continuously monitored. Cardiac output, pulmonary arterial pressure, and total pulmonary vascular resistance were assessed by echocardiography. Venous blood was sampled before and 3min after exercise cessation to analyze blood viscosity and NO end-products. At sea level, athletes with EIH exhibited an increase in blood viscosity and NO levels during exercise while NEIH athletes showed no change. Pulmonary hemodynamics and aerobic performance were not different between the two groups. No between-group differences in blood viscosity, pulmonary hemodynamics, and V˙O2max were found at 1 day after arrival in hypoxia. At H5, lower total pulmonary vascular resistance and greater NO concentration were reported in response to exercise in EIH compared with NEIH athletes. EIH athletes had greater cardiac output and lower SpO2 at maximal exercise in H5, but no between-group differences occurred regarding blood viscosity and V˙O2max. The pulmonary vascular response observed at H5 in EIH athletes may be involved in the greater cardiac output of EIH group and counterbalanced the drop in SpO2 in order to achieve similar V˙O2max than NEIH athletes.

Influence of Migration and Plugging of Nanoparticles on Coal Permeability in Coal Reservoirs

The plugging of nanopores in low-permeability coal reservoirs is an important factor that affects productivity reduction. However, the mechanism of plugging of the nanopores in coal reservoirs remains unclear. In this study, the coal samples from the Anze coalbed methane block of the North China Oilfield are used as the research object. Experiments are conducted on the mechanism of nanopore plugging by the variation of nanopore permeability based on the pressure oscillation method and the nanopore (scanning electron microscope) method. The research shows that the foreign working fluid invades a coal sample; the sample changes from being hydrophobic to being water absorbent within a certain period. The instability caused by the expansion of coal clay mineral particles promotes the dispersion and shedding of particles, and the migration of particles is accelerated under the shear stress of the working fluid. In addition, the viscosity and pressure difference of the working fluid are important factors that affect particle plugging. The viscosity of the fluid increased by two times, and permeability decreased by 1.21 times. As the pressure difference increases by two times, permeability can be reduced by up to two orders of magnitude. The findings of this study can help for better understanding of the mechanism of plugging of the nanopores in coal reservoirs and the reasons of production reduction in low-permeability coal reservoirs. Such findings provide theoretical support for the selection of the working fluid, and reasonable production pressure difference can effectively reduce the damage on coal permeability in a low-permeability coal reservoir.

Alkylimidazolium Ionic Liquids Absorption and Diffusion in Wood

Ionic liquids represent a class of highly tunable organic compounds responsible for many applications in the domain of wood-based materials. It has often been emphasized that the use of ionic liquids derives from their high affinity for lignocellulose and their good penetration ability into wood structures. This paper discusses the sorption ability of different types of 1-alkyl-3-methylimidazolium ionic liquids with lateral alkyl chains, ranging from ethyl to hexyl into spruce and beech wood, as a function of their cation molecular mass, anion type (chloride, tetrafluoroborate, acetate), and intrinsic properties (surface tension and kinematic viscosity) at room temperature. All the studied ionic liquids present high relative uptake values at the equilibrium, ranging from 11.2% to 69.7%. The bulk diffusion coefficients of the ionic liquids into the wood range from 2 × 10−3 to 28 × 10−3 mm2/min, being higher in the longitudinal direction for both types of wood. The value of the diffusion coefficients for 1-ethyl-3-methylimidazolium chloride is only 25% lower than that for water, despite the obvious differences in viscosity and surface tension, demonstrating a good penetration ability and the potential for wood industry-related applications (as impregnation compound carriers and preservatives).

Visualization of Local Concentration and Viscosity Distribution during Glycerol-Water Mixing in a Y-Shape Minichannel: A Proof-of-Concept-Study.

The work presents an efficient and non-invasive method to visualize the local concentration and viscosity distribution of two miscible and non-reacting substances with a significant viscosity difference in a microchannel with a Y-shape cell. The proof-of-concept setup consists of a near-infrared (NIR) camera and cost-effective dome lighting with NIR light-emitting diodes (LED) covering the wavelength range of 1050 to 1650 nm. Absorption differences of glycerol and water and their mixtures with a mass fraction of glycerol from 0 to 0.95 were analyzed in the NIR spectral area. The resulting measurement images were converted in a concentration profile by using absorbance calculated with Lambert–Beer law. A linear behavior between the concentration and the absorption coefficient is demonstrated. The result of local concentration in mass fraction was used to determine the local viscosity and illustrated as distribution images. By variating the fluid parameters, the influences of the highly different original viscosities in the mixing procedure were investigated and visualized.